(Đồ án tốt nghiệp) research, design and implementation of a coconut shell shredder and dehydrator machine for organic fertilizer production

INTRODUCTION

Introduction

1.1.1 A brief overview about coconut fruit.

As the above- mentioned, coconut plays a vital role in Vietnam's agriculture With more than

175.000 ha of coconut area, coconut is the fourth most critical perennial plant in our country As also cited in

[6], Mekong Delta takes almost 80% of total coconut production, especially in Ben Tre province and Tra Vinh province, about 72.000 ha and 20.000 ha, respectively Fig 1.1 Vietnam coconut production (ICC)

The coconut tree has enormous potential for both the economy and the environment. Most coconut tree parts can be used For example, coconut trunks and leaves can be used as construction material, and coconut water and coconut flesh are valuable indigents for cuisine and oil manufacturing Regarding the environmental aspect, the coconut tree is one of the few trees that can cope with harsh conditions like drought, waterlogging, and nutrient-poor soil.

Besides these parts, which can be directly used after harvest, the coconut shell is most likely forgotten Although two main elements in coconut husk are coco peat and coco fiber are widely used in both industrial and agriculture—especially coco peat, which is a vital ingredient for organic fertilization.

Coco peat is a non-fibrous, lightweight substance that holds the coco fiber and coconut shell together This is the product of the Coconut Fiber Extraction process Coco peat is 100% organics ingredient for agriculture, especially for fertile production It is because it has high moisture retention when it is dry and can retain up to 800% [7] of moisture Organic fertilization with coco peat as the main ingredient can support the airflow to roots by improving soil aeration improving soil buffering Coco peat can store and release nutrients in advance of spongy nature characteristics Finally, in general, coco peat is renewable sources of material and 100% natural that can constantly fill up the demand for zero chemical fertilization, which keeps trendy nowadays.

1.1.2 Structure and general mechanical properties of coconut fruit.

The picture above illustrates the cross section structure of the coconut fruit Most of rich-nutrition part like white flesh or coconut milk are already used for other purpose This is the reason why we need to focus on the parts which provide us coconut coir and coco peat The table below show the percentages of each part of coconut fruit.

Fig 1.2 Structure of coconut fruit.

Table 1.1 Distribution of coconut fruit.

We will concentrate on the coconut coir and coco peat-related stuff for this project. Our primary achievement is to extract coco peat and coconut coir from coco husk So, we need to have some input data about the mechanical properties of these layers The following table, based on previous research from Tra Vinh University, contains some of the essential properties of coconut husk

Table 1.2 Mechanical properties of coconut husk [5]

Bonding force of coconut coir.

Statics friction coefficient of coconut husk = 0.42~0.45 contact with steel by inner smooth surface.

Statics friction coefficient of coconut after = 0.57 ℎ proceeded with steel shredding machine and

Maximum shear stress For fresh coconut: 189.5 N

For gray husk: 201.7 N For dry husk: 263.3 N

Fig 1.3 Mechanical properties of coconut shell [24]

1.1.3 Investigate the market of coconut shredder machine.

Currently the market for coconut shredder machine is a mix Although shredder machine is quite popular in Vietnam but most of them are focus on other product instead of coconut husk.

About Vietnamese manufacturer, there are two company participate in this field are Moc Kim Son (MKS) [8] company and 3A Agriculture Machinery [9] These machine and specification are showed as a table below.

Table 1.3 Specification of MKS and 3A machine Specification Unit Moc Kim Som company 3A Agriculture Machinery

Main material Plate steel, I beam V5 steel, 2mm sheet metal

Input material Fresh/dry husk Fresh/dry husk

Fig 1.4 Coconut shredder machine from MKS and 3A

With all the information we have as summarized above, we have some analyze about the advantages and disadvantages of both machines from Vietnamese manufacturers.

About coconut shredder machine from MKS It clearly that this machine is much more superior compared to the same product from 3A It is obvious because they have two separate mechanisms to crush and shred the coconut husk They also have belt conveyor to transfer the output material onto varied type of container of difference machine like screw drive.

By contrast to 3A machine with the price is less than 12 times compared to MKS machine They have simple mechanism is rotating blade to shred the coconut husk And their machine frame looks not that rigid and lack of safety to operate But 3A machine have much more range of application not only for coconut husk but also for difference product like grass or bough And the price is 12.500.000 VND, quite affordable for small scale business.

To summarize both machines, we listed they pros and cons to the table below.

Table 1.4 Pros and Cons about MKS and 3A machine MKS shredder machine 3A shredder machine

Pros 2 separate mechanism for Simple mechanism, low maintaining better output material quality cost High productivity High productivity Rigid machine frame Inexpensive price

Cons High cost for purchasing and Bad frame machine design, make maintaining output material fly out of machine.

Too heavy, hard to Machine frame not rigid. transportation.

Not suitable for small business.

In terms of international manufacturers, although India and Sri Lanka both have the highest coconut production among other countries, their machine seems slightly outdated and lacks safety and aesthetics.

There are two notable companies from China and Brazil that have all-around performance coconut shredder machines They are Xtmachinery [11] and JF company [12], and their machine specification will be listed in the table below

Table Specification of Xtmachinery and JF machines

Table 1.5 Specification of Xtmachinery and JF80 machine Specification Unit Xtmachinery XT65*27 JF 80

Main material Plate steel, I beam V5 steel, 2mm sheet metal

Input material Fresh/dry husk Fresh/dry husk

Fig 1.5 Coconut shredder machine from XTmachinery and JF Brazil

In the same process with Vietnam manufacturing, we will analyze both their advantages and disadvantages.

On the one hand, the coconut shredder machine from china uses a hammer mill with a full circle screen, and two rotor shredder mechanisms are the superior features It is proper because, with two rotors, they can shred much more coconut each time, and a full circle screen can vastly reduce the time for each operating circle because the coco peat can be removed faster Due to the full circle screen, it would be hard to replace the screen for maintenance.

On the other hand, a product from JF Brazil is much more compact but has performance as good as China's product They use a hammer mill mechanism with a single rotor and haft circle screen By using a single rotor, the machine become much more mobility with quite suitable for small-scale business They are also compatible with the tractor but require double the power compared to an electric motor.

Overall, both machines have extremely high productivity The pros and cons are listed in the table below.

Table 1.6 Pros and Cons about Xtmachinery and JF Brazil Xtmachinery machine JF 80

Pros Double rotor shredder Compact size, mobility mechanism

Full circle screen Compatible with both electric motor and tractor High productivity High productivity Cons High cost for purchasing High cost for purchasing

Not mobility , too much Lack of safety aspect. heavy ( 1000 kg)

Hard to maintenance due to full circle screen.

In conclusion, the market for coconut shredding machines is quite active in our country and on a global scale This is appropriately because of the tendency to recycle coconut husk not only for economic aspects but also for the environmental view.Although all development in this field, it seems like manufacturers still focus on large scale industry instead of small-scale business The price of three out of four machines is over 100.000.000 VND which can be a big deal for individual purchasers.

The urgency of the topic

Nowadays, the need for coconut in Vietnam and other countries seems to keep high demand This led to the promotion of coconut production on both a small and large scale.

In mass production for harvesting and processing coconut, we apply some noticeable technology to fully use the potential of coconut trees like an enormous system from taking coconut milk, grinding coconut flesh to shred all the leftovers into coco peat and coconut coir But the investment for such a massive system like this is risky for small- scale businesses.

This alarming trend can be solved if we have a tool or a machine that can process their coconut husk in two-step: Shredding their coconut husk on a smaller scale and squeezing water remaining in the post-processing material And this machine must have an affable price for small-scale businesses If we can come up with this solution, we can solve most of the above problems.

This is why we choose the topic: Research, design, and implementation of a

Objection of the project

We already listed the coconut shredder machine that already sold in the market not only in our country but also as international lever Both of them have they own pros and cons like having high productivity But three out of four tagged with the price above 100.000.000 which is unaffordable for small scale business Not to mention they lack of dewatering mechanism and some machine like from XTmachinery to complicated to maintain.

So that, our project will focus on these following aim:

- Easy to maintain shredding mechanism.

Research method

- Experimental analysis for gathering input data and testing machine after manufactured.

- Theoretical calculation for design and calculating machine component.

Aim, mission and scope of the project

- Aim of the project: Coconut shell shredder and dehydrator machine, calculation report, technical drawings.

- Mission of the project: Design and implement fully functional prototype of coconut shell shredder and dehydrator machine with reasonable price for small scale business.

+ Appling theatrical knowledge about mechanical design and machine manufacturing to solve

+ Time for designing and manufacturing is 5 months.

Input data

- Input material: fresh or dry coconut husks.

1.6.2 Define input data about coconut husk:

Beside the minimum force to break the coconut husk, we need two more real data about weigh and overall dimension of coconut husk So that, we will be using experimental method to investigate these properties.

Weigh of the coconut husk:

About weigh of the coconut husk, we considering these data by recording 5 coconut husk samples for fresh and dry in total of 10 samples.

Table 1.7 Overall weigh of fresh and dry coconut husk Experiment No Fresh coconut husk (gram) Dry coconut husk (gram)

Fig 1.6 Fresh and dry coconut weigh

We can observe that the overall weigh of fresh coconut is much more higher compared to dry coconut due to the loss of water and outer cover This lead to the conclusion that with dry coconut, it would be easier to shredding and does not require dehydrator mechanism By contrast to fresh coconut husk with high contain of water and kind of sticky, we need to shred it and using dewatering mechanism to squeeze it.

Size of the coconut husk:

For the size of the coconut husk, we measuring 5 difference sample for fresh and dry in total of 10 samples We using tape measurement to record the overall height and width as well as diameter of sample The data also listed in the table below.

Table 1.8 Overall dimensions of fresh and dry coconut husk Experiment No Fresh coconut husk (cm) Dry coconut husk (cm)

Height Width Diameter Height Width Diameter

Fig 1.7 Overall size of fresh and dry coconut husks.

Based on the result of this experiment, we know that the size of fresh coconut is considerably bigger than dry coconut With this data, we can also decide the dimension for the feed hopper must be at least 17 cm.

Table 1.9 Input data about coconut husk

INPUT DATA ABOUT COCONUT HUSK

Condition of coconut husk type Fresh and dry

Average weight of fresh coconut husk kg 1220

Average weight of dry coconut husk kg 278

Destroy stress of coconut husk N/mm2 1.25 × 10 6

- The output material much pass through 16mm screen hole diameters.

- The fresh coco peat as considerable dry condition after processing

- After processed, fresh material including coco peat and coconut coir Table 1.10. Output material for organic fertilizer.

OUTPUT DATA ABOUT COCONUT COIR AND PEAT

Type of output material type Cocopeat, coir and powder

Expecting output data

Shaft shredding machine are the machine that use 1 or more shaft to reduce the size of material This type of machine is widely used in agricultural like in corn powder, fodder manufacturing, yeast, or lipid…

The principle of shaft shredding mechanism is structure will grind the large particle or grains to smaller size when they pass though the tight gap between shafts Based on type of machine, there are different shredding times depend on the hardness of input material and required size for output material For example, if the material is sticky and durability, we need to use mechanism shaft 2 type VII or shaft 2,3,4 type IX in fig 2.1. For the small grains or beans, we can use 2 or 4 shafts shredding mechanism.

Most of these shafts are casted with special cast iron like (C 3.2% ~ 3.7%; Si 0.4

~0.7%; Mn 0.2 ~ 0.8%; P 0.5%; S 0.14%; N 0.25%) High surface hardness HB 370-

450 For harder shaft (around 500 HB), the shaft structure consists of 2 parts: Core of shaft made by cast iron and outer covered by Crom-Nikel alloy.

Fig 2.1 Mechanism of shaft shredder [3] Fig.2.2 Double shafts shredder machine [12]

LITERATURE REVIEW

Shredding mechanism

Shaft shredding machine are the machine that use 1 or more shaft to reduce the size of material This type of machine is widely used in agricultural like in corn powder, fodder manufacturing, yeast, or lipid…

The principle of shaft shredding mechanism is structure will grind the large particle or grains to smaller size when they pass though the tight gap between shafts Based on type of machine, there are different shredding times depend on the hardness of input material and required size for output material For example, if the material is sticky and durability, we need to use mechanism shaft 2 type VII or shaft 2,3,4 type IX in fig 2.1. For the small grains or beans, we can use 2 or 4 shafts shredding mechanism.

Most of these shafts are casted with special cast iron like (C 3.2% ~ 3.7%; Si 0.4

~0.7%; Mn 0.2 ~ 0.8%; P 0.5%; S 0.14%; N 0.25%) High surface hardness HB 370-

450 For harder shaft (around 500 HB), the shaft structure consists of 2 parts: Core of shaft made by cast iron and outer covered by Crom-Nikel alloy.

Fig 2.1 Mechanism of shaft shredder [3] Fig.2.2 Double shafts shredder machine [12]

This mechanism using shape blade rotating on the tight chamber to cut down material by the sheer force of the blade The blade structure can be three or four blade with special angle slop so that the flow of material will be from the top to the bottom At the bottom of this type of machine, there are also attaching with screen to sorting the desirable size.

Fig 2.3 Rotary blade mechanism by 3A machinery [9]

Most of the machine using this mechanism is direct transmission or belt drive transmission The blade need to rotate at least 1400 rpm to fully functional Although the machine structure is simple, but this mechanism only suitable for grass or softer material. For coconut husk which is hard for dry one or ductile for fresh one, this mechanism is not suitable.

Fig 2.4 Rotary blade mechanism in food industry

The shredder principle of hammer mill mechanism is based on the impact of hammer onto materials, the impact of materials onto the side of machine and the rubbing between each of them.

General speaking, the process of hammer mill mechanism consists of 4 steps:

1 Material go into the machine by gravity

2 These material will be shredder by hanged hammer that fixed or freely rotated onto the shaft with high rotation speed.

3 The material is crushed or shattered by repeated hammer impacts, collisions with the walls of the grinding chamber, and particle on particle impacts.

4 Small grains or material then go through the screen with designated holes.

2.1.4 Comparison and choose shredder mechanism.

Table 2.1 Advantages and disadvantages of shredder mechanisms

Mechanism Shaft shredding Rotary blade Hammer mill

Advantages - Very high - Simple structure - High efficiency. efficiency.

- Easy to build - Simple drive

- Suitable for small mechanism. output material. business - Fine output material.

- Easy to maintaining output material and cleaning.

- Varies type of input material.

Disadvantages - Too complex to - Low efficiency - Cannot achieve very build.

- Low adjustability fine output material.

- Hard to maintain - Hard to maintaining the screen.

- Require high power motor to properly run.

Shaft shredding Rotary blade Hammer mill

After carefully analyzing and comprising each shredder mechanism Our group choose hammer mill mechanism because it much more suitable for our requirements and has more advantages compared to others mechanism.

Transmission system for shredder mechanism

Gear drive or gear transmission trains are the transmission mechanism that transfers the rotary motion and moment from other shaft and machine components They are widely used as the primary mechanism for speed gearbox, engines, and turbines They have some superior characteristics, like they can transmit high torque and slight backlash. There are varies type of gear like external gear, internal gear, spur gear, helical gear, bevel gear, spiral bevel gear.

In this project, we can use external gear transmission with drive gear attached to the motor's shaft and the driven gear fixed on our hammer mill mechanism Although all the advantages, we need to carefully consider using this drive because our shredder mechanism is quite dangerous if it gets stuck and our driven shaft cannot rotate; using gear drive transmits motion based on the matching principle that can overload our motor. Not to mention that gear drive is considered complex to machine manually on a milling machine We also need to adequately cover it when it runs because the tiny grain of our coco peat can drop into this drive and ruin the surface of both gears We cannot increase the shaft distance with the matching principle unless we use intermedia gear.

A chain drive is the transmission mechanism that transfers the rotary motion and moment from one shaft to another The traditional chain drive usually consists of two or more chain sprockets and links The chain links match with the chain sprocket to transmit motion Same with gear drive, chain drive has zero slip thanks to the matching principle, so that the chain drive could maintain the velocity evenly Because using chain links, they can adjust the shaft distance depending on user requirements.

Applied to this project, we can use two chain sprockets, one fixed on the motor’s shaft and the other fixed on the shredding mechanism Due to the zero slip, using chain drive for the hammer mill mechanism is risky because there is nothing to protect the motor from being overloaded Furthermore, the chain drive is very noisy when working at high speed Moreover, the chain link and sprocket are tough to machine, and they wear extremely fast when not appropriately oiled Chain drive also requires clean operating conditions, which is unsuitable for applying near our hammer mill shredder mechanism. Nevertheless, we can apply chain drive in our dehydration mechanism thanks to the zero slip.

The belt drive uses the frictional principle to transmit motion and torque unlike the two transmissions as mentioned earlier The structure is identical to a chain drive with two or more pulleys connected with the belt There is various type of belt drive, including round belt, flat belt, V belt, toothed belt, and link belt Compared to chain drive or gear drive, belt drive is much cheaper, but it still can manage to handle the role of transmission.

The belt drive is astonishingly suitable for the hammer mill mechanism as a transmission system First, the most important factor is that this transmitting motion by frictional principle, then mean when our output shaft is getting any problem like broken bearing unit or getting struck that cannot rotate, our belt will slip onto the pulley so that the motor cannot get stuck and keep rotating That feature helps to protect the motor from being overloaded and creates a burning smell that notices our worker or operator stops the machine Secondly, like chain drive, we can adjust the shaft distance of two shafts, which is much more flexible for design Thirdly, the belt drive does not make too much noise when operating at high speed than the chain drive It can work in a dusty environment suitable for our hammer mill mechanism.

2.2.4 Comparison and choose transmission drives for shredder mechanism.

Table 2.3 Advantages and disadvantages of transmission drives

Mechanism Gear drive Chain drive Belt dive

Advantages - Constant velocity - Constant velocity - Lower cost

- Compact size - High mechanical - Slip belt to protect

- Zero slip efficiency motor from overload

- Can transfer high - Versatile shaft - Easy to distance manufacturing torque

- Can transfer low - Easy to maintenance. rpm

- Can work in dusty environment.

Disadvantages - Hard to - Hard to - Losing speed due to manufacturing manufacturing slip belt.

- Hard to - Very noisy at high - Transmission ratio is maintaining, require speed not stable. clean environment.

- Cannot protect maintenance, require motor from overload clean environment.

Gear drive Chain drive Belt drive

Which all the discussion, we can observe that belt drive is much more compatible and affordable compared to chain drive and gear drive So that, our group decided to choose belt drive as a transmission drive for hammer mill shredding mechanism.

Motor type selection for hammer mill shredder mechanisms

3-phase motor is the most popular electric motor used around the world It responsibility is to transferring electrical energy into mechanical energy (in this cases are rotating motion).

Generally, 3-phase motor consist of two main part: Stator and Rotor The working principle is when the AC current run through the stator that create the rotating magnetic field (RMF) is produced in the motor This field rotating around the stator with synchronous speed:

Then, this RMF go through the air gap between stator and rotor This field also cut the rotor conductor Thanks to the motion between rotating magnetic field and rotor This phenomenal create the short circuit and the flux inducted on it and create rotational motion.

Fig 2.9 3-phases motor working principle [17]

Although 3-phases motor is a good mechanical power for this project Our aim is to create the machine for small scale business that can work in 220V electrical system or 1-phase electric If we wish to use this type of motor, we need to add inverter to transfer 1-phase electric onto 3-phase electric which can significantly boosting the cost.

1-phase motor or single phase motor is almost identical with squirrel cage three phase motor in term of structure They have two main parts: Stator and rotor which stator is stationary part while rotor is a rotating part.

Single-phase motor consists of two windings including: Main windings and auxiliary winding When the supply connects to the main winding, capacitor is linked in series with auxiliary winding to generate the shift in phase in term of current between main and auxiliary winding.

Unlike 3-phase motor which can self-starting, 1- phase motor need to use the capacitor to start and increase the cost factor.

Fig 2.10 Wire diagram of 1-phase motor [18]

Fig 2.11 1-phase induction motor structure [19]

When using 1-phase motor, we can get rid of the problem about electrical system for small business who most likely can only use 1-phase electric With our target is create the machine for small-scale business, we choosing 1-phase induction motor as our main mechanical power for hammer mill shredder mechanism.

Dehydrator mechanism

The structure of screw press dehydrator including a cylinder that is fixed Inside this cylinder is the rotating screw The dehydrator principle is that the input material (in our project is coco peat) is transferred by the screw Then these material is compressed continuously thank to the screw pitch is getting smaller and smaller By this compressed force, the water was pressed and pass through the screen and we get dryer output material.

In industry, the screw press system including sludge inlet where the input material go through There are 2 main zone including thickening zone and dewatering zone which is each haft on the screw.

Fig 2.12 General structure of a screw press mechanism [20]

Screw press mechanism has some advantages like high efficiency, high capacity, easy to operate But in our project, the input material for dehydrator mechanism is coco peat is containing not that much water compared to sludge So that using this mechanism for our project is not efficiency Not to mention the fact that the screw is considerably hard to machining and maintaining, which is also not meet our ambition is implementing the machine for small scale business.

Belt press or belt filter press is the mechanism used for removing water from the material They use the same principle with screw press is using the compression force The mechanism consists of 2 belt with material inside these belt Then these belt and material go through one or the series of press roller couple By using the tension force of the belt press and the tight gap between them The water then goes through the belt so that the belt material much be special.

Fig 2.13 Belt press mechanism applied in industry [21]

In our project, using industrial belt press much be over engineered So that we want to applying this mechanism in much more basic concept that we have one belt conveyor which transferring the material from the shredder mechanism to the dehydrator mechanism The dehydrator mechanism will consist of two rollers that let the belt and material go through them in small gap This mechanism is possible because it simple, and the efficiency is acceptable for the coco peat material.

In conclusion, after carefully considering two type of dehydrator mechanism, our group choosing simple belt press for dehydrator mechanism because: compared to the screw press, belt press is much easier to maintaining and operating Also belt press is not too complex so that the price to machining these parts will be acceptable Which is match the small-scale business In addition, we using chain drive for this simple belt press because we need the

MECHANICAL DESIGN

Block diagram

POWER SUPLLY Providing 1-phase 220V electrical energy for the machine which suitable for small-scale business

ELECTRICAL BOX Receiving electrical power from POWER SUPPLY then distributing this energy and signal to actuators of this machine

MOTOR 4KW Receiving electrical power and signal form ELECTRICAL

BOX This motor transferring the electrical into mechanical power which powering the belt drive.

BELT DRIVE Transferring mechanical power (moment) from MOTOR

4KW to HAMMER MILL MECHANISM.

HAMMER MILL The main component of our shredder mechanism They

MECHANISM receiving rotational energy from MOTOR 4WK through

BELT DRIVE to shred our coconut husk

SCREEN SCREEN received the material processed though

HAMMER MILL MECHANISM Only material with desirable size can pass though this SCREEN.

MOTOR 0.75 KW Receiving electrical power and signal form ELECTRICAL

BOX This motor transferring the electrical into mechanical power which powering the chain drive.

CHAIN DRIVE Transferring mechanical power (moment) from MOTOR

0.75KW to BELT CONVEYOR and PRESS PULLEY MECHANISM.

BELT CONVEYOR Transferring the shredded material to PRESS PULLEY

PRESS PULLEY Squeeze out the water from the shredded mechanism.

MACHINE FRAME Fixing and holding the whole machine.

INPUT MATERIAL The material we want to preceded: Coconut husk

OUTPUT Our desired material after processed by the machine: coco

MATERIAL peat and coco coir with less water

DEHYDRATED Leftover water or dehydration process.

Fig 3.1 Block diagram of coconut husk shredder and dehydrator machine

The coconut husk shredder and dehydrator machine using two separate mechanisms:

Hammer mill mechanism and press belt mechanism A 1-phase motor 4kw transferring the electrical energy into rotational energy to the belt drive and power up the hammer mill mechanism to shred all our input material These material will be sorted by the screen to ensure the suitable size Then these shredded mix will be transferred to the press pulley mechanism by belt conveyor to squeeze water into dehydrated water and we have the final mix of output material which coco peat and coco coir at desired size and less water. The belt conveyor and press pulley mechanism powered by 1-phase motor 0.75kw through the chain drive All the component of this machine was fixed on the strong and stable machine frame which is constructed by welded steel bar.

The machine is providing the electric power supply with 1-phase and 220V- suitable for small-scale business Then the electrical power and signal are distributed by the electrical box through the button, signal light and series of electrical equipment.

Design and calculate the hammer mill mechanism

Fig 3.2 Mechanism diagram of hammer mill

In order to choosing the right motor for hammer mill mechanism We need to considering varies input data, the first thing we need to calculate is the velocity of hammer mill.

Based on [3], the velocity of hammer mill determined by this formula:

By formula (3.1), in order to destroy the material after each crush, the necessary velocity must be 1.5 or 2 times the destroy velocity.

So, the velocity when smashing multiple time according to [3]

- V fv : Destroy velocity when smashing multiple time.

- k cl : Mechanical properties of material.

First, we need to find the shredding coefficient in multiple time In our case, our machine is for small scale business so the times required to shred the coconut husk is long By that point, we choosing the smashing time is 6 times.

So we have the shredding coefficient: λ)] (3.2)

In case of 1-time smashing, the required velocity is: k d σ pv ln ( a

- a: the length of material (mm) choose a = 167 mm average size [5]

- x 1 : the non-deform size of material (our desired output material) (mm) Choose x 1 = 0.75 ( varies from 0.5~1).

- ρ: specific weight of material (kg/m 3 ) ρ = 390 m kg

- σ fv : destroy stress (N/m 2 ) Choose σ fv = 1.25 × 10 6 m N

In order to shredding the material in one smashing require the high amount velocity. From the point of machining and energy this is unacceptable So that we need to smashing the material more times for optimizing the price and energy This is the reason why we need to considering the velocity of hammer mill in case of multiple smash.

Then, the rotational speed of hammer mill: ω n = 2π (rpm) (3.5)

With: r: The diameter of drum (mm).

3.2.2 Choosing motor for hammer mill mechanism.

With: n: Rotational speed of hammer mill n = 2515 rpm.

A: Work required for shredding material Based on this formula:

- Z: Number of hammer mill on machine Z= 32.

Required power for hammer mill mechanism:

- đ : efficient coefficient of belt drive đ = 0.92

Choose motor with 4 Kw in power and 1450 rpm in rotational speed.

3.2.3 Calculating belt drive for hammer mill mechanism

Since the driving shaft of the belt transmission are mounted on the motor shaft, the input parameters are taken on the motor shaft.

- Power on the driving shaft: P = 4 Kw.

- Rotational speed of driving shaft: n = 1450 rpm.

Selection belt and cross section:

- We have power P d = 4,3 (Kw), rotating speed n d = 1425 (rpm) According to figure 4.1 page 59 in [1]

- => Choosing type A belt (GOST) or type A belt (TCVN) based on [1] Select diameter of belt drive:

- We determine the diameter of the belt wheel according to the table 4.13 [1].

- Selecting d 1 = 200 mm based on the standardize: 63 , 71 , 80 , 90 , 100 , 112

Calculating the velocity of driving pulley:

Calculating the diameter of driven pulley:

- Choosing the diameter of driving pulley 2 = 112 based on [1] So, the real transmission ratio is:

Check for error of belt transmission ratio:0.56

3.2.3.3 Calculating center distance of belt drive:

- The shaft distance must satisfy this formula:

= 1737.2 ( ) Choosing l = 1800 mm based on standard on 14.3 in[TC].

Calculating the exact length of shaft distance

- Based on formula 4.6 in [TC]

- Based on formula 4.7 in [TC]

3.2.3.4 Calculating the number of belt:

- According to formula 4.6 in [TC]

- P 1 = P d = 4 (kW): Power of driving pulley

- K đ = 1.5: coefficients of dynamic load (work 2 shifts) (table 4.7) [1]

- C α = 0,98: coefficient of angle wrap’s effect (table 4.15) [1]

- C l = 1: coefficient of length’s effect (table 4.16) [1]

- C u = 1,135: Coefficient of ratio’s effect (table 4.17 [1])

- C z =0.95 Coefficient of load’s effect (table 4.18 [1])

3.2.3.5 Calculating the width of and outer diameter belt pulley.

- Based on formula 4.17 and table 4.21 in [TC], the width of belt pulley

- Outer diameter of belt drive calculated by formula 4.17 in [TC]

3.2.3.6 Calculate the initial tension and the force acting on shaft.

- Calculating 0 based on formula 4.19 in [TC]

Table 3.3 Parameter of belt drive

Power on driving shaft P 4 kW

Rotation speed of driving shaft n 1450 Rpm

Diameter of driving pulley d 1 200 mm

Diameter of driven pulley d 2 112 mm

Width of the belt B 50 Mm

3.2.4 Calculating the shaft for hammer mill mechanism:

- Chose the shaft’s material is C45 Steel (quenching), strength stress σ b = 650 MPa

- The torque stress allowance [τ] = 15÷30 (MPa).] = 15÷30 (MPa).

- Power on hammer mill shaft: ụ = đ = 4 × 0.92 × 0.995 = 3.66 (Kw)

- By the working diagram, we need to calculate the load diameter at three position: Hammer mill fixing, bearing, and belt pulley.

- Position for each machine component:

Fig 3.3 Force diagram on hammer mill shaft.

Fig 3.4 Free body diagram of hammer mill shaft.

- Determine the forces and moments acting on shaft: On xOz:

Fig 3.5 Force and moment diagram of hammer mill shaft on yOz plane.

Fig 3.6 Force and moment diagram of hammer mill shaft on xOz plane

- Equivalent moment at each cross section At cross section A:

- [ ]: allowable stress of shaft material = 63 (MPa) based on table 10.5 [1]

- We only considering the diameter at dangerous cross section In this case this is at A, belt pulley cross section, hammer mill cross section

At belt pulley cross section:

At hammer mill cross section:

Finally, we have the diameter for the shaft:

Table 3.4: Diameter at each cross section of shaft Diameter value (mm) 35

3.2.4.3 Verify the strength condition for shaft

- At dangerous cross section: bearing assembly cross section σ −1 = 0.436σ b = 0.436 × 600 = 261.6 (MPa) τ −1 = 0.58σ −1 = 0.58 × 261,6 = 151.7 ( )

- Calculating σ aj and σ mj based on 10.22 in [1] σ mj = 0 σ aj = σ maxj =

- Calculating τmj and τaj based on 10.23 in [1] τ mj = τ aj = τ maxj

- Calcu lating K σdj and K τdj based on 10.26 in [1]

At belt pulley cross section

- Calculating s σj and s τj based on 10.21 in [1] s σj = σ −1

- Finally, calculating sj based on formula 10.19 in [1]

=> sastify the strengh condition 3.2.4.4 Verify the strength condition for key

- Based on table 9.1a on [1] we choosing keyway with this diameter:

3.2.4.5 Choosing bearings and verifying the bearing condition.

- Total forces acting on bearing:

- We verify the strength at the bearing that bear bigger load: = 1084.38 (N)

- Choosing the ball bearing SKF 6270 with pillow housing and the diameter:

Table 3.6 Ball bearing SKF 6270 specification:

Notation d (mm) D (mm) C (kN) Co (kN)

- Verify the bearing based on dynamics load:

- = 1 coefficient about the number of rotation.

- Verify the stress based on static load

In order to prevent the residual deformation, the ball bearing need to satisfy the condition:

Design and calculate the press pulley dehydrator mechanism

Fig 3.7 Mechanism diagram of press pulley

3.3.1 Choosing motor for press pulley mechanism

- The power of belt conveyor motors calculated based on

- 1 : required power for the belt conveyor working without load (kW)

- 2: required power for the belt conveyor working with horizontal load (kW)

- 3: required power for the belt conveyor working with vertical load (kW)

- f: friction coefficient of ball bearing

- W: weigh of moving component in conveyor

- : weigh of product in length unit (kg/m)

- V: velocity of belt conveyor (rpm)

- : Length of belt conveyor by horizontal (m)

- : Length of belt conveyor by adjusting length (m)

- : distribution weigh of belt conveyor

- : weight of rotating component (kg)

- : weigh of rotating component in return direction (kg)

- Productivity of belt conveyor based on [1]

- A: area of cross section of material flow (m 2 )

- V: velocity of belt conveyor (rpm)

- : specific weight of material (tones/m 3 )

- : coefficient depend on the slope

- Calculating weigh of moving component:

Our belt conveyor is less than 1m so we don’t use branch => = 0

- With: efficient coefficient of chain drive

- ổ: efficient coefficient of ball bearing

- Choosing motor with power is 0.75 kW, number of revolution is 50 rpm (with reducing gearbox)

- Belt tension force on shaft:

With V is belt conveyor speed.

With is the wrap angle of belt conveyor on shaft.

Table 3.7 Transmission distribution ratio of dehydrator mechanism

Because the load and velocity is low, so we using roller chain.

- With u=1, choosing 1 = 24, so that the number of teeth on the rest is z$.

= 1 (Center line and sprocket have the angle < 60 )

= = 0.208 × 1.43 × 1.042 × 1 = 0.310 ( ) Based on table 5.5 in [1], with 01 = 50 ( ), choosing 1 line chains with =

Using Inventor to calculate the perimeter of chains is 2359.71 mm

3.3.2.2 Verify the strength of chain drive

According to the KANA model 40-1X10FT, the fatigue load is Q100 N. Weight of 1m of chain drive is q=0.61 kg. đ = 1.2 According to working condition

According to table 5.10 in [1] with n = 50 rpm, [s]=7 So s > [s]: Satisfy the fatigue condition.

According to the formula 5.17 and table 13.4 in [1]:

- Pitch circle diameter of chain sprocket.

- Using C45 steel, quenching to reach the hardness HB210 will reach allowable stress [ ] = 600 MPa Satisfy the condition.

- Calculating forces acting on shaft based on formula 5.20 in [1]

- Chose the shaft’s material is C45 Steel (quenching), strength stress σ b = 650 MPa

- The torque stress allowance [τ] = 15÷30 (MPa).] = 15÷30 (MPa).

- Torsional moment at working shaft:

- Initial diameter of working shaft

Fig 3.8 Force diagram on press pulley.

Fig 3.9 Free body diagram of press pulley - Total moment based on: = 0

- Total force based on direction y= 0: + − =0

- Total force based on direction x = 0:

Fig 3.10 Force and moment diagram of press shaft on xOz plane.

Fig 3.11 Force and moment diagram of press shaft on yOz plane.

At belt pulley cross section:

At hammer mill cross section:

Table 3.8: Diameter at each cross section of shaft

- At dangerous cross section: d = 45 cross section σ −1 = 0.436σ b = 0.436 × 600 = 261.6 (MPa) τ−1 = 0.58σ−1 = 0.58 × 261,6 = 151.7 ( )

- Calculating K σdj and K τdj based on 10.26 in [1]

- Calculating s σj and s τj based on 10.21 in [trinh chat] s σj = σ −1

- Finally, calculating sj based on formula 10.19 in [trinh chat]

- Based on table 9.1a on [1], we choosing keyway with this diameter: Table 3.9

- We verify the strength at the bearing that bear bigger load: = 1964.4 (N)

Fig 3.12 Force diagram of belt conveyor shaft

- Total force based on direction y= 0: + = 0

- Total force based on direction x = 0:

Fig 3.14 Force and moment diagram of belt conveyor shaft

Table 3.11: Diameter at each cross section of shaft

- At dangerous cross section: d = 30 cross section σ −1 = 0.436σ b = 0.436 × 600 = 261.6 (MPa) τ−1 = 0.58σ−1 = 0.58 × 261,6 = 151.7 ( )

- Calculating Kσdj and Kτdj based on 10.26 in [1]

- Calculating s σj and s τj based on 10.21 in [1] s σj = σ −1

- Finally, calculating sj based on formula 10.19 in [trinh chat]

- Based on table 9.1a on [1], we choosing keyway with this diameter:

- We verify the strength at the bearing that bear bigger load: = 673.42(N)

MANUFACTURING PROCESS

Hammer mill mechanism machining process

Fig 4.1 Assembly drawing of hammer mill mechanism Hammer mill mechanism is the main mechanical actuator of our machine This mechanism constructed by 9 different machine elements including: main shaft, hammer mill shafts, bushes, hammers, screws, washer, side plate, core plate, key Three core components: main shaft, hammer mill shafts and bushes was machined by our team thank to the equipment at Viet-Duc Center Others components was outsourced and purchased by various suppliers At the first of this section, we will go from the elements we machined by our self then the elements from others vendors.

The main shaft is the heart of our hammer mill mechanism It received the rotational motion and moment from motor through belt drive Then this motion and energy was transferred to other component (hammer) to create the smashing force.

+ Tolerances for assembly: At the step diameter we need to assembly bearing

In this case we use clearances fit then fixed it by the screws of bearing

+ Keyway: This shaft will be assembled with pulley of belt drive, so that it will have the keyway.

4 Material removal allowances and machining methods.

+ Material removal allowances: the largest diameter is 40mm and the leght of

55 shaft is 510 mm So we choosing the C45 cylindrical structure steel with diameter and length are 45mm and 530mm respectively.

+ Machining method: Turning on engine lathe and milling on milling machine for keyway.

Table 4.1 Machining routes for main shaft.

No Route Steps Machine Cutting Fixture tool

1 Face turning Face turning Carbide 3 jaw chuck insert tool

Drilling center Center drill bit

2 Face turning to Face turning Lathe Carbide 3 jaw chuck reach 510 mm machine insert tool parameter

3 Rough turning Rough turning to 41 Carbide 3 jaw chuck mm insert tool and tailstock

Rough turning to 37 mm for the step diameter

4 Rough turning Rough turning to 37 Carbide 3 jaw chuck mm for the remain insert tool and tailstock step diameter

5 Finishing Finishing turning to Carbide 3 jaw chuck turning ∅40 40 mm insert tool and driving center tip

6 Finishing Finishing turning to 3 jaw chuck turning ∅35 35 mm and tailstock

7 Finishing Finishing turning to 3 jaw chuck turning ∅35 35 mm and tailstock

8 Tape M8x1.25 Drilling Drill bit 3 jaw chuck

9 Milling Milling keyway 10x5 Milling End mill Vise with keyway machine ∅8 support pillar

Fig 4.2 Technical drawing of main shaft

- Cutting condition for each routes: Route 1: Face turning:

- Deep of cut: choose t= 5mm.

- Feed rate: According to [2] page 8, choose S = 1.5 mm

- Cutting speed: According to formula in [2] page 9

Follow the table 1.1 in [2], we have:

Table 4.2 Parameter for face turning m T

Follow the table 9.1 we have:

Route 2: Face turning: Same condition with route 1 until reach 510 mm.

Route 3: Rough turning to 41 mm and 37 mm for the step diameter:

- Deep of cut: choose t= 4 mm.

- Feed rate: According to [2] page 8, choose S = 1 mm

WithIn this route, the only parameter that change is = 1 based on table 10.1 in [2].

Route 4: Rough turning to 37 mm for the step diameter: same cutting condition with route 3.

Route 5: Finishing turning to 40mm diameter

- Deep of cut: choose t= 0.5 mm with 2 steps

- Cutting speed: According to table 5.19 in [3], we have = 200 /

Deep of cut: choose t= 0.5 mm with 4 steps

Feed rate: According to [2] page 8, choose S = 0.1 mm

Cutting speed: According to table 5.19 in [4], we have = 200 /

- Deep of cut: 2.5 mm for 2 steps

Table 4.3 Parameter for milling keyway m T

Fig 4.3 Main shaft machining on lathe machine at Vietnamese-German Center

Fig 4.4 Main shaft machining on milling machine at Vietnamese-German Center

4.1.2 Hammer mill shaft machining process

Fig 4.6 Technical drawing of hammer mill rod.

The hammer mill shaft plays a vital role in this mechanism It secure hammer and let them rotating freely on shaft.

+ Tolerances for assembly: We want the hammer freely rotating on shaft so we need to use clearance fit.

- Material removal allowances and machining methods

+ Material removal allowances: the largest diameter is 20mm and the length of shaft is 250 mm So we choosing the C45 cylindrical structure steel with diameter and length are 22mm and 300 mm respectively.

+ Machining method: Turning on engine lathe

2 Face turning to Face turning Lathe Carbide 3 jaw chuck reach 300 mm machine insert tool parameter

3 Rough turning Rough turning to 20.5 Carbide 3 jaw chuck mm insert tool and tailstock

Semi-finishing turning to 20 mm

4 Tape M8x1.25 Drilling Drill bit 3 jaw chuck

5 Cutting condition for each routes: Route 1: Face turning:

- Deep of cut: choose t= 5mm.

Step 1: Rough turning to 20.5mm

- Deep of cut: choose t= 1.5 mm.

- Feed rate: According to [2] page 8, choose S = 1 mm

WithIn this route, the only parameter that change is = 1 based on table 10.1 in [2].

Step 2: Semi-finishing turning to 20mm

- Deep of cut: choose t= 0.5 mm.

- Cutting speed: According to table 5.19 in [4], we have = 200 /

Fig 4.7 Hammer mill shaft machining at Vietnamese-German Center

Fig 4.8 Technical drawing of bushes

The bushes function is to constraint the movement of hammers on hammer mill shaft

+ Tolerances for assembly: These bushes assembly onto hammer mill shaft easily and freely rotate So that we choose clearance fit.

- Material removal allowances and machining methods

+ Material removal allowances: the largest diameter is 40 mm and the length of bush is 20 mm So we choosing the C45 cylindrical structure steel with diameter and length are 40mm and 23 mm respectively.

+ Machining method: Cutting work piece on band saw machine Turning and drilling on engine lathe.

1 Cutting work Cutting work Band saw Band saw Vise piece piece in to 23mm machine

3 Face turning to Face turning Carbide 3 jaw chuck reach 20 mm insert tool parameter Lathe machine

4 Drilling Drilling hole Drill bit 3 jaw chuck

Deep of cut: choose t= 0.5mm.

Feed rate: According to [2] page 8, choose S = 1.5 mm

Cutting speed: According to formula in [2] page 9

Fig 4.9 Cutting work piece and drilling bushes at Vietnamese-German Center

Fig 4.10 Final product of bushes

4.1.4 Side plate and center plate:

Fig 4.11 Technical drawing of side plate

Fig 4.12 Technical drawing of center plate

- Functions of machine component: The side plate and center plate are the parts that connecting and fixing main shaft and hammer mill shaft together.

+ Tolerances for assembly: 4 holes in each plate must have clearance fit for easy assembly

- Machining method: This is sheet metal part which kind of hard to machining by our self because the lack of proper equipment So that we outsource it to HONG DAT Technical Co Ltd., They used laser cutting machine to cut this part Fig 4.13 Center and Side plates

Fig 4.14 Technical drawing of hammer mill

These hammers mill will be hanged on hammer mill shaft and rotating freely When the machine working, these hammers will contact with material to crush it up.

+ Tolerances for assembly: 2 holes in each plate must have clearance fit for easy assembly

- Machining method: This is sheet metal part which kind of hard to machining by our self because the lack of proper equipment So that we outsource it to HONG DAT Technical Co Ltd., They used laser cutting machine to cut this part.

4.2 Hammer mill cover manufacturing process

Fig 4.16 Hammer mill cover Hammer mill cover is the machine block that containing the hammer mill mechanism This structure helps our mechanism working properly, avoid the fly of material which is danger to operator As follow the design of hammer mill mechanism, this structure has 4 main parts that connected with each other: upper cover, middle cover, lower cover and screen.

The upper cover is use to guide the material onto the hammer mill mechanism and protect the operator from the flying particle in shredder process

+ Material: 5mm SPC sheet steel and 10mm SPC sheet steel for rib

- Machining method: This is sheet metal part which include 2 machining methods: laser cut, welding.

- Bill of materials (BOM): Because these part we outsource to Hong Dat

Technical Co Ltd so we need to made the BOM to get the quote.

Table 4.8 Bill of materials for upper cover

No Name of part Quantity Material Images

Table 4.8 Bill of materials for upper cover (cont.)

After we have BOM, we export all the related sheets and component into technical drawing, as well as assembly drawing to vendor.

Fig 4.18 Upper cover assembly drawing

Fig 4.19 Upper cover final product 4.2.2 Manufacturing middle cover

Fig 4.20 Middle cover technical drawing

The middle cover is use to fix the hammer mill They also have auxiliary side ledges for better shredding efficiency.

Table 4.9 Bill of materials for middle cover

- The middle sheet 5 is hard to machining It consists of bending metal sheet with

5 iron bars welded onto it

- Same with the upper cover, we need 6 holes with 13mm diameter to joint these together by M12 screws.

- The middle covers also have 22.5mm radius haft circle for the main shaft can go through and connected with ball bearing.

- The ribs in the sheet 4 are to increase the sturdiness of machine.

Fig 4.21 Middle cover technical drawing

Fig 4.23 Lower cover technical drawing

The middle cover is use to fix the hammer mill They also have auxiliary side ledges for better shredding efficiency.

Table 4.10 Bill of materials for lower cover

Table 4.10 Bill of materials for lower cover (cont)

Fig 4.24 Lower cover assembly drawing

Fig 4.27 Screen cover technical drawing

- Functions of machine component: The screen function is to sorting the desirable size of material we want to get This screen can slide onto lower cover easily and have a cover.

+ Material: 4mm SPC sheet steel

- Machining method: This is sheet metal part which include 3 machining methods: laser cut, welding and bending.

Fig 4.30 Machine frame technical drawing

- Functions of machine component: The machine frame is the most vital component in our machine This frame bears all the load from mechanism, motor, spare parts, electrical boxes So that we need to carefully calculating and manufacturing.

+ Material: Various type of profile steel which will listed in the section below. + Feature: 4 wheels and take-up mechanism to make the machine moving freely.

- Machining method: This frames mostly implemented by steel cutter and welded.

Table 4.11 Bill of materials for machine frame

Fig 4.31 Welding drawing of machine frame

Fig 4.34 Machine frame wheel and take-up mechanism assembled and painted

The dehydrator mechanism consists of the structure of 4 rollers connected with textile belt and receive the power and motion by motor through the chain drive

These rollers are quite big and hard to machining in Vietnamese-German Center so we outsourced it to the local mechanical shop.

Fig 4.35 Driving shaft technical drawing

Fig 4.36 Driven shaft technical drawing

Roller fixture plate: Outsourced at HongDat Technical Company

Fig 4.37 Roller support plate technical drawing

Fig 4.38 Support plate welded onto machine frame

Fig 4.39 Assembled rollers on machine

Dehydrator mechanism manufacturing

The machine including 2 main mechanism including hammer mill mechanism and press belt dehydrator mechanism We assembly of the machine following this path:

As mention earlier, the hammer mill mechanism consists of 9 main parts The main shaft will be attached with 3 plate (2 side plates and 1 center plate) by welding The rest parts will be connected by tolerances and temporally joint like screw-nut.

In order to make it easier for precise welding, 3 plates, hammer mill shaft, bushes and hammer mills will be assembled first to create the frame.

Then we assembled the shaft onto the assembly above with 2 UCF ball bearing. Finally, we fixed it onto machine frames and weld 3 plates onto main shaft.

After that, we assembly lower cover, hammer mill mechanism, middle cover and upper cover onto machine frames based on this procedure:

Fig 5.2 Hammer mill mechanism assembly

MACHINE ASSEMBLY PROCEDURES

Hammer mill mechanism assembly

As mention earlier, the hammer mill mechanism consists of 9 main parts The main shaft will be attached with 3 plate (2 side plates and 1 center plate) by welding The rest parts will be connected by tolerances and temporally joint like screw-nut.

In order to make it easier for precise welding, 3 plates, hammer mill shaft, bushes and hammer mills will be assembled first to create the frame.

Then we assembled the shaft onto the assembly above with 2 UCF ball bearing. Finally, we fixed it onto machine frames and weld 3 plates onto main shaft.

After that, we assembly lower cover, hammer mill mechanism, middle cover and upper cover onto machine frames based on this procedure:

Fig 5.2 Hammer mill mechanism assembly

Fig 5.3 Assembly hammer mills and bushes onto hammer mill shaft and plates

Fig 5.4 Assembly last side plate onto the mechanism by screws and washes

Fig 5.5 Assembly the lower cover onto machine frame

Fig 5.6 Finished assembly of hammer mill mechanism

Hammer mill mechanical drive: belt drive

According to the calculation, we need belt drive with 3 lines of belt, the type of belt is V-belt A-60.

First, we need to assembly two pulley onto mechanism shaft and motor shaft.

Then fixed the motor onto machine frame so that it linear with the pulley of hammer mill shaft.

Finally, we attach 3 lines of belt on to the drive and have some final adjustment.

Fig 5.7 Belt drive assembly process

Fig 5.8 Belt drive assembly in practice.

Press belt mechanism assembly

The press belt mechanism consists of 3 main parts: support plates, pulleys and belt

The system of 4 pulleys will be assembled onto the machine frame by the support plates welded onto machine frame.

First, we need to weld support plates onto machine frames at right position Then we assembly the top and bottom pulley with UCF and take-up housing, as well as the belt onto these pulleys.

Next, we assembly the couple of pulleys for dehydrator mechanism with UCF and take-up housing.

Finally, we need some last adjustment with the position of each pulley the belt itself,

Fig 5.9 Dehydrator mechanism assembly procedure

Fig 5.12 Assembly front pulley, belt and under pulley

Press belt mechanism drive: chain drive

According to the calculation, we use roller chain with complex structure The motor transferring the power to driving sprocket, then transferring it again into 3 driven sprockets by chain links.

Electrical box wiring and assembly

The requirement is we need to control 2 1-phase motors, beside common practice function, we need to turn on and off these motor separately and together This is the reason why we design this wiring diagram.

The contactor for 4kw motor required the calculation to choosing it, if not, our contactor as well as thermal relay will not be able to bear the current required for the motor.

In this case, the power of motor is 4kw = 4000 w, the 1 phase grid in our country is 220V and= 0.8 So that the electric quota of this motor:

The starting current of 1-phase motor is around 5~7 time the Idm, so that we need the bigger contactor Following the experiment for fast choosing contactor, we have:

For the thermal relay, according to the figure below, we have 1-phase 4kw motor

So that we choose 24A thermal relay.

As we know, the starting current of 1-phase motor is higher than its own current, so we need to choose the right CB Usually, the starting current is around 3~5 times the nominal current, so that:

So we choose 40A CB for this machine.

Electrical wire also the important factor we need to considering, if we choose too small diameter of wire, the current will not enough to start the motor, if we choose too big diameter, the price of this machine will increase astronomical.

According to [23], with the power 4kw, we should choose 10mm diameter wire.

Fig 5.18 Exterior electrical box Fig 5.19 Interior electrical box

After putting all major and small parts together, with some adjustment, our group successfully assembled the machine.

Fig 5.21 Frond and back views of finished machine

Fig 5.22 side views of finished machine

EXPERIMENT AND ANALYSIS

Analysis

Table 6.13 1-time sampling test results and comments

Material 100% Most of the static test meet the tolerances Design of body frame 100% and requirement except “Weight” and

Design of hammer mill 100% “Overall dimension” mechanism Most of our mechanical component

Design of dehydrator 100% manufactured on machine tools are mechanism precise and working well, but others elements was welded So that we cannot

Working mode 100% avoid the displacement between each

Drive cover 100% component The weight of this machine

Upgrade machine 100% component also fall of our expected because there is some component heavier than normal.

Fig 6.1 Starting time (s) Comment: The starting time mainly focus on the required time for the main motor (hammer mill motor) to run stable at maximum speed Because we use 1-phase motor, so we need time for the fuse to pulse the energy into motor and run at stable speed Most of time, we will need at least 8 seconds for the machine to properly run and get ready for shredding But in some case there are a problem related to the drive or the electrical, it will take a little bit longer to get stable stage.

Time required to change the screen (s) (static)

Time requred to change the screen

Fig 6.2 Time required to change the screen (s) Comment: This is the time we need to spent each time we want to change to others type of screen It mostly around 34 seconds But sometime, there are the stuck coconut coir on the machine so it makes longer to take out the screen.

Maximum size of input material (mm)

Fig 6.3 Maximum size of input material (mm)Comment: In this experiment, we try our best to put the largest coconut husk onto the machine which still make the machine work properly The largest size is 220mm At experiment 9 and 10, we put 240mm and 230mm coconut husk into the machine but it gets stuck, so the largest size up to now is 220mm.

Maximum size of output material (s) (dynamic)

Maximum size of output material (mm)

Si ze o f o u tp u t m at er ia l ( m m )

Fig 6.4 Maximum size of output material (mm) Comment: The maximum size of output material data is mostly the length of coconut coir because the coco peat is too small for considering The thickness of coconut coir is much smaller than our screen so it can pass out easy But the length of them is quite longer than our expected So that our machine only bears out 80% of the test required

Fig 6.5 Working noise (Db) Comment: We run the machine and then using our smartphone to record the value of noise by app Our machine is considerably noisy because we have the lack in dynamic balancing, so our hammer mill mechanism is very noisy By contract to our dehydrator mechanism which is quite and smooth.

Maximum weigh of input material per minute

Maximum weight of input material per minute

Fig 6.6 Maximum size of weight of input material per minute (kg/hour) Comment:

We try our best to put as much as coconut husk into the machine But due to a lot of factor like the top cover is quite small and for the safety factor, the best we can do is 14kg per minute and average about 11.5 kg per minute.

At first time we try to run the machine with load, went we start to shred couple of coconut husk, the coconut coir gets stuck in our screen too much so that it blocks the outlet of our machine Although the hammer mill mechanism can work perfectly fine but the output material cannot go through to the next stage so we need to have some adjusting with the screen.

After we adjusting the screen and start to run in second time, the machine has the problem because the belt conveyor is too near the outlet, so that our coconut gets stuck between the hammer mill mechanism cover and belt conveyor At last, our machine can reach up to 14kg of coconut husk per minute.

Fig 6.7 First load experiment, coconut coir stuck at screen

Fig 6.8 Coconut coir get through after fixing the screen

Fig 6.9 Coconut coir get stuck dual to the outlet is small at high output material volume

Fig 6.10 Coco peat and coconut coir drop out of the belt conveyor

Specification Imp Unit Ideal Marginal Measured value % name value value Match

Design of body 2 list Part list in Chapter 4 100% frame

Design of 5 list Part list in Chapter 4 100% hammer mill mechanism

Design of 3 list Part list in Chapter 4 100% dehydrator mechanism

Maximum size 3 mm 200 100 220 100% of input material

Maximum size 4 mm 50 60 50.4 80% of output material

Maximum 4 Kg/min 15 10 11.5 56.6% weigh of output material per minute

Time required 2 s 30 40 34.3 45% to change screen

Working mode 1 list Low suction force 100%

Medium suction force High suction force

Drive cover 1 list Belt cover 100%

Upgrade 2 list Chain tensioner 100% machine component

Overall, the matching rate is about 80%, not meet our expectancy although the expectancies are set at moderate low level There are two experiments have lowest performance are: “Time required to change screen” and “Maximum weigh of output material” recorded at 45% and 57% respectively.

For the first one, we have two main reasons that lead to the latency of this task First, our screen takes out position is not a good position which is blocked by our press roller So that it requires more effort to remove the screen Secondly, the coconut coir sometime gets stuck between the screen and the fixture plate and make it harder to put out the screen.

For the second one The main reason why this not meet our requirements is the design of inlet and outlet of hammer mill mechanism cover The inlet is quite small so that we cannot put too much material onto the machine at one time The screen and the belt conveyor are to close that lead to the output material getting stuck between them. The solution for these problems are: Redesign the upper cover, optimize the screen and adjusting the distance between screen and belt conveyor.

In conclusion, after series of experiments and analysis Our machine although cannot meet our requirement but still a usable machine after some adjustments.

Fig 6.11 Conclusion graphic about the experiment

IMPROVEMENT, RESULT AND CONCLUSION

Improvements

In order to enhance the quality of life, safety and mechanical aspect of our machine.

My group have several improvements and addition into this machine

Fig 7.1 Belt drive with cover

Fig 7.2 Chain drive with cover The belt and chain cover play an importance role to protecting the operator from the risk of getting injuries by these drive They also prevent the dusks form coco peat and working environment, as well as enchant the aesthetics of the machine.

The chain tensioner helps to fix one of our chain drive problem – loosened chain by using small sprocket that freely rotate on the shaft.

Result

After six months of research, design and implementation Our group finally finished our coconut husk shredder and dehydrator machine using hammer mill mechanism and press belt mechanism Our machine capabilities are:

- The machine can shred the coconut husk properly regardless the condition.

- The output material (coco peat and coconut coir) partly meet our requirement.

- The hammer mill mechanism work effectively.

- Safety with feeding door mechanism and drive cover

- Productivity is about 720 kg/hour Much higher than we expectation.

Beside the capability, our machine still has a few weakness including:

- Hammer mill mechanism create very annoying sound (about 103.7 Db).

- The inlet and outlet quite small for higher feed rate of material.

- The dehydrator mechanism is not that efficiency.

Conclusion

Overall, our machine was finished with fully functioned hammer mill mechanism and press belt mechanism The machine generally reaching 80% of our expectation. Although the productivity is not meet our requirement, but this still considerable high compared to the same machine on the market For example, the same machine from MKS company limited, with same motor power at 4kw, but they productivity is about two or three husks per minute while these price is about 80 million VND Compared to our machine with take about 35 million VND while productivity is 11.5 kg per minute Just about 1/2 the price but the efficiency is much higher Although our machine aesthetics, dynamic balancing and others mechanical stuff are weaker than MKS After the capstone project, this machine will be transferred to Khoa Thanh Dat company limited at D555A , Long Binh Ward, Bien Hoa city, Dong Nai province as technology transfer.

Despite the fact that we try our best in both design and implementation, but the lack of time and the financial problem as well as our self that make our machine have few disadvantages First, we cannot afford the polyester belt conveyor which would take about 8 million VND, so that we using textile belt instead That lead to our dehydrator mechanism work not that well although they can squeeze the water on the mix of output material The next problem is our inlet and outlet are not that optimized design, so we cannot put too much material onto the machine at once which decrease our productivity. The last thing is our first screen design is not that good for coconut coir, the coir getting stuck frequently between the holes of screen so that we need to change to different design which is sacrifice the output material quality.

After the machine finished, we also try our best to improving our machine We already add drive cover for belt drive and chain drive as well as assembly the chain tensioner for better and stable chain drive To make it easier for transporting, we added four high quality wheels as well as take-up mechanism when the machine working We also fixed the inlet of upper cover for the safety.

For the future improvement, we want to adding some feature and improving our existed machine including:

- Dynamics balancing our hammer mill mechanism.

- Changing the textile belt into polyester belt or chain link belt.

- Redesign and implement the cover for hammer mill mechanism.

- Adding belt conveyor system to providing material onto the machine automatically.

- Design and implement the auto packing system for the coconut and coco peat.

- Adding the inverter on both motor so that our machine can work at 3-phase grid.

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[2] Nguyen Ngoc Dao, Tran The Sang, Ho Viet Binh “Chế độ cắt gia công cơ khí”

[3] Tran Nhu Nam, Tran Thi Thanh “Máy gia công cơ học nông sản – thực phẩm”. Vietnam Education Publishing House, 2000.

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Production-Factory-Professional-Wood-Sawdust-Coconut-Shell-Grinder-Machine.html

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%20belt%20filter%20presses%20work,the%20case%20of%20primar y%20sludge

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Tiêu đề	Research, Design And Implementation Of A Coconut Shell Shredder And Dehydrator Machine For Organic Fertilizer Production
Tác giả	Chu Huy Hoang, Dang Ngoc Thien, Hoang Huu Nghia
Người hướng dẫn	Phan Thanh Vu, ME
Trường học	Ho Chi Minh City University of Technology and Education
Chuyên ngành	Machine Manufacturing Technology
Thể loại	graduation project
Năm xuất bản	2022
Thành phố	Ho Chi Minh City

Định dạng
Số trang	147
Dung lượng	13,33 MB