Trang 1 FACULTY FOR HIGH QUALITY TRAINING RESEARCH, DESIGN AND FABRICATION OF AUTOMATIC MACADAMIA NUTS SHELLING MACHINE Trang 2 MINISTRY OF EDUCATION & TRAINING HCMC UNIVERSITY OF TECH
INTRODUCTION
Problems
Macadamia trees, originally cultivated in Australia since the mid-19th century, gained global recognition by the mid-20th century and are now highly valued commercially In Vietnam, macadamia cultivation began in 1994 in Ba Vi, Hanoi, and has since expanded to various provinces, particularly in Tay Nguyen and Tay Bac Despite being a relatively new crop in Vietnam, macadamia nuts are among the most expensive nuts worldwide, and the country ranks as one of the top 11 in terms of macadamia tree acreage With ongoing efforts to promote macadamia planting in these regions, the growing area continues to expand, positioning macadamia products as potential key agricultural exports in the near future.
Macadamia nuts are versatile ingredients found in various products such as ice cream, cooking oils, canned cakes, and cosmetics, or enjoyed directly in canned form These processed items often command significantly higher prices than untreated macadamia nuts A crucial step in their production involves the labor-intensive and time-consuming process of separating the kernel from the hard, brittle, and uneven shell of the macadamia nut, which poses challenges for automation.
Shelling macadamia nuts without breaking the kernel is crucial, as damaged kernels complicate the processing of macadamia nut products This challenge significantly contributes to reduced productivity and profitability for small and medium-sized macadamia nut processing facilities.
The urgency of the topic
As Vietnam's economy and population continue to grow, macadamia nuts have emerged as a highly nutritious and promising crop Despite the rapid expansion of the macadamia nut processing industry, domestic production fails to meet consumer demand, leading to a reliance on imported nuts The number of processing factories remains limited, primarily located in Tay Bac and Tay Nguyen, and their output is insufficient to satisfy the increasing market needs Additionally, some processing facilities in Ho Chi Minh City rely on raw materials sourced from Tay Nguyen, utilizing labor-intensive methods that compromise product quality.
The project "Research, Design, and Implementation of an Automatic Macadamia Nut Shelling Machine" addresses the need for automation in the macadamia nut separation process This initiative aims to reduce labor costs, enhance productivity in nut separation, and streamline processing times to meet the growing demand for macadamia nuts Additionally, the introduction of this automatic shelling machine will foster the trend of automation in agricultural production, particularly in the granular food sector.
Scientific and practical significance of the topic
1.3.1 Scientific significance of the topic
- Creating conditions and premise for application of knowledge and skills learned in real life
- Creating a new product for our country, contributing to process of "industrialization and modernization of the country"
- Raise the value of macadamia nuts in domestic
1.3.2 Practical significance of the topic
- The topic is carried out to help the macadamia nut shelling to be done quickly, with high productivity and quality to meet the current needs of the market
- Meet the needs of small and medium production facilities Helping establishments save labor costs Instead, they can invest in macadamia nut shelling machine to serve the processing.
Goal of the topic
After the project is completed, the following problems will be solved:
- Give the principle of macadamia nuts shelling
- Automation for input feeding process
- Automation for processing of separating macadamia nuts
- Shelling efficiency is more than 80% and the broken kernel efficiency is less than 10%
- Calculate and complete the design for the macadamia nut shelling machine
- Simulate and test operation of the machine
- Manufacturing and assembling complete machines.
Object and scope of the study
- Dried macadamia nuts with sizes from 25 to 30 mm
- Method of separating macadamia nuts
- Types of macadamia nuts shelling machine
- Input material: dried macadamia nuts
- Manufacturing and testing macadamia nuts shelling machine
- Expected capacity of the machine: 80kg/h
- The scale is suitable for medium and small macadamia nut processing facilities.
Research methods
- Learn and research the current methods of macadamia nuts shelling on the market
- The manual method of macadamia nuts shelling depends mainly on the skills of workers, so productivity is low and labor cost high
The macadamia nut shelling machines currently available on the market often fall short of the needs of processing facilities, primarily due to significant drawbacks such as a high percentage of unsplit nuts and pricing that is not aligned with the budget constraints of local processing operations.
- Collect materials from scientific articles, journals, textbooks and internet sources related to the research content
- Analyze advantages and disadvantages of domestic and foreign methods of separating macadamia nuts From there, we propose a solution for an automatic macadamia nuts shelling machine
- Using the experimental parameters along with the theoretical basis of the calculation to design the parts of the macadamia nuts shelling
1.6.4 Finite element analysis and modeling method
- Use finite element analysis to determine the toolpath profile
- Using modeling methods to design machine models
- Measure the size of the dried macadamia nut
- Experiment to determine the toolpath profile to minimize the kernel breakage rate of macadamia nuts
- Prototyping the macadamia nuts shelling machine, then operate test to get parameters and complete design
Structure of the study
- Chapter 6: Fabrication and experiment – Evaluation.
OVERVIEW
General introduction about macadamia nuts
The macadamia tree, a hardy species native to subtropical regions of southeastern Queensland and northern New South Wales, Australia, was first introduced to the Hawaiian Islands in the 1880s as a windbreak for sugarcane farms Its sweet nuts, developed through research by the Hawaii Agricultural Research Center, led to its rise as a commercially valuable crop Today, macadamia trees are cultivated globally in countries such as Australia, South Africa, the USA (Hawaii), Kenya, China, and Vietnam, primarily for their seeds As of 2019, macadamia nuts rank among the most expensive nuts worldwide.
2.1.2 Mechanical properties and nutritional value of macadamia nuts
- Fresh macadamia nuts are round or tapered to the bottom, with a diameter range from 20-30mm, a weight ranging from 8-9g/nut, with a husk about 3mm Macadamia fruits have a
When ripe, the macadamia nut's husk splits along one seam, revealing the brown nut inside These nuts, classified as hard fruits, have a shell that is 2-5mm thick, while the kernel is a milky white with a yellowish hue, making up nearly one-third of the nut's weight Rich in fat and aromatic, macadamia nuts are a nutritious and flavorful addition to various dishes.
- Macadamia nuts have a delicate taste, rich in taste and especially macadamia nuts are very nutritious and contain many calories, fats, vitamins and minerals beneficial to health
- Based on the research results of the United States Department of Agriculture, in each 100g of macadamia kernels have the following nutritional content[𝟏𝟓]:
Table 2.1: The main nutritional composition of macadamia nuts Nutritional ingredients Amount Unit
- In additional, macadamia nuts also bring many health benefits:
+ Reduce bad cholesterol to promote heart health, while reducing the risk of heart attack, stroke
+ The antioxidants in macadamia nuts work very well to prevent free radicals, helping to supplement antioxidants
Macadamia nuts are low in sugar and carbohydrates, while also providing a moderate amount of fiber that effectively helps regulate blood sugar levels This makes them an excellent choice for individuals with diabetes, as they can contribute to a reduced risk of metabolic syndrome.
Rich in fiber, this seed supports the growth of beneficial gut bacteria and stimulates their activity, leading to the production of short-chain fatty acids These compounds help reduce inflammation and lower the risk of irritable bowel syndrome, ultimately promoting improved intestinal health.
+ There is a lot of protein and fiber that makes you feel full for longer, supporting healthy, effective weight loss
+ The compounds tocotrienols and flavonoids in macadamia nuts can help prevent and fight cancer cells, contributing to prevention of dangerous cancers
+ Plant compounds tocotrienols will help promote brain health, protect brain cells, prevent the risk of some diseases such as Parkinson or Alzheimer disease
The global consumption of macadamia nuts has surged due to their nutritional value and numerous health benefits Typically enjoyed roasted or dried, macadamia nuts are now featured in a variety of high-value products thanks to advancements in the processing industry These innovative macadamia-based products are increasingly available in international markets, showcasing the versatility and appeal of this popular nut.
Figure 2.3: Products made from macadamia
(1) Macadamia oil (4) Macadamia nut milk
(2) Macadamia nuts chocolate (5) Sweet soup
- Macadamia oil: can be classified as premium because of its attractive taste, which has the effect of supporting health, lowering cholesterol and preventing heart-related diseases
- Macadamia nuts chocolate: taste of macadamia nuts creates a natural sweetness, reduces the bitterness of chocolate and makes chocolate more crispy
Macadamia nut milk is a heart-healthy beverage packed with monounsaturated fats that aid in lowering cholesterol and triglyceride levels Additionally, it is rich in flavonoid antioxidants and vitamin E, which contribute to slowing down the aging process.
- In addition, macadamia filling can be used in combination in traditional Vietnamese dishes, such as banana ice cream with macadamia nuts, moon cakes, macadamia nut salad, granola
Macadamia kernels and shells are utilized in the cosmetic industry for their whitening properties, while also serving as high-heat fuel and organic materials for plant incubators and potting soil Additionally, essential oil derived from macadamia flowers is valued in perfumery and premium cosmetics.
Figure 2.4: Processing of macadamia nuts
- Macadamia nuts are usually harvested in May to August every year, its main season in July and August
The harvesting method involves collecting ripe nuts that have fallen to the ground or shaking the tree to drop them onto the surface below To maintain the quality of the final product, it is essential to consider various factors during the harvesting process.
+ Collected nuts need to be ripe enough, preferably fallen nuts
+ Nuts must be collected daily to reduce losses due to rats and squirrels
To maintain the quality of macadamia nuts, it is crucial to dehusk them promptly after harvesting Delaying this process allows the essential oil in the kernel to develop, resulting in nuts that are oily and have an unpleasant odor.
- After harvesting, macadamia nuts need to be spread evenly in the shade Avoid leaving for too long, avoid direct sunlight
Figure 2.6: Macadamia nuts after removed husk
- After dehusking, macadamia nuts are sorted by size to suit the needs of consumer
Macadamia nuts are categorized into two primary sizes: those measuring 23-25mm and those ranging from 25-28mm, with occasional larger nuts reaching up to 30mm The price of macadamia nuts varies based on their size.
- The larger the size of the macadamia nuts, the higher the selling price and conversely
- Macadamia nuts after dehusking, will still have a lot of pus and impurities macadamia nuts need to be washed to remove these pus substances, to avoid unsightly final product
- During the washing process, we can also easily remove insect, flat nuts, which are float on the surface of the water
Figure 2.7: Macadamia nuts cleaning machine
Macadamia nuts undergo a two-stage drying process to effectively reduce moisture and achieve optimal dryness The primary goal of dehumidification drying is to prepare the nuts for storage by ensuring they meet quality standards Additionally, drying plays a crucial role in ripening the nuts, making them suitable for direct consumption.
In Stage 1, after the husk is removed and the kernels are cleaned and dried with a blower, the moisture content is approximately 15% The goal of the drying process is to reduce this moisture to about 2-4%, while also minimizing the increase of essential oils in the nuts.
Table 2.2: Procedure of drying stage 1 [16]
Step Temperature ( o C) Dehumidification (minutes) Moisture balance(hours)
Figure 2.8: Macadamia nuts drying machine HTB to reduce moisture
In Stage 2 of nut processing, the dried nuts undergo high-temperature heating to enhance their ripeness, resulting in a rich, fatty, and aromatic flavor The specific drying methods and equipment used can vary based on the taste preferences and processing techniques of each facility.
Table 2.3: Procedure of drying stage 2 [16]
To achieve optimal dryness and crispiness in macadamia nuts, it is essential to allow for a longer drying time Additionally, higher drying temperatures enhance the nuts' aroma; however, excessive heat can lead to burning.
Figure 2.9: Macadamia nuts drying ovens
The macadamia nut, known for its hardness, poses significant challenges in the shelling process, which typically requires specialized tools or machines In many regions, unskilled labor is still employed for this task, resulting in an average output of only 70 kg per person per day, leading to high time and labor costs This inefficiency has prompted the development of automated solutions for macadamia nut shelling, aiming to streamline the process and reduce reliance on manual labor.
Figure 2.10: Manually shelling the macadamia nuts
- Macadamia nuts after being shelling will be quantified and packed by vacuum method
- In addition, macadamia nuts can also be packed directly into zip bags with desiccant packs The storage time of vacuum-packed dried beans can last for more than 6 months.
Survey of input materials
2.3.1 Experiment to get data on the size of macadamia nuts
+ Determine sizes of dried macadamia nuts Based on the existing results as a basis for design process
+ Determine distance between two fixed V-block
+ 100 dried macadamia nuts were purchased in Dak Lak province
Figure 2.12: Measure macadamia nuts Table 2.4: Results of measuring the size of 100 macadamia nuts Diameter max From 25 to
2.3.2 Experiment to get size data of macadamia nuts shell thickness
+ Determine thickness of the macadamia nut shell, thereby serving as the basis for the calculation of cutting depth
+ Determine profile of the toolpath
Figure 2.13: Mesure macadamia nuts shell thickness Table 2.5: Results of measuring size of 25 macadamia nuts shell (tolerance ±0,1mm) Thickness
Shell thickness on top side
Shell thickness on base side
Shell thickness on lateral side
Published foreign and domestic research results
2.4.1 Published foreign domestic research results
In recent years, the global consumption of macadamia nuts has surged, with a notable increase in demand across major markets like North America and Europe This trend is expected to continue as macadamia nuts gain popularity in developed countries such as the United States, Japan, South Korea, and New Zealand, due to their nutritious profile and health benefits.
Figure 2.14: Import quantity of macadamia in the world in 2020[1]
The popularity of macadamia nut products has surged globally, leading to the development of a thriving macadamia processing industry that offers a wide range of high-value products available in nearly all international markets These nutrient-rich nuts are primarily enjoyed roasted or dried, which accounts for over 60.6% of their consumption Additionally, macadamia nuts serve as essential ingredients in the confectionery and ice cream sectors, comprising 30.3% of their usage, while also being utilized in beverage production, including milk and soft drinks, which accounts for 9.1%.
Figure 2.15: Percentage of products processed from macadamia nuts in the world[1]
The ongoing advancement of the food industry has led to the emergence of a supportive processing sector In developed countries like China and Australia, the macadamia nut separation process has become largely automated This automation encompasses a nearly closed-loop system that includes hard shell separation, classification, and packaging of macadamia nuts.
Processing facilities vary significantly across provinces, with some regions having only one or two, while others boast numerous establishments For instance, Lam Dong province is home to 28 processing facilities, and Dak Lak province has 15 Additionally, Ho Chi Minh City features industrial processing facilities that produce a range of products, including cooking oil, shampoo, and milk.
Specialized machinery for processing macadamia nuts includes essential equipment for dehusking, drying, and dehumidifying While many companies utilize basic machines, some, like TH True Milk Company, are investing in advanced technology to produce innovative macadamia milk products.
Research on automation in the macadamia nut shelling process in the country remains limited Nonetheless, notable advancements include the macadamia nut sawing machine developed by Phu Thinh Company and an automatic macadamia nut shelling machine created by students at Ho Chi Minh City University of Technology and Education.
Figure 2.16: Macadamia nut sawing machine of Phu Thinh Company
The simplicity of current domestic technology highlights the urgent need for automating the macadamia nut shelling process As global trends shift towards advanced production and processing of agricultural products, our country is beginning to prioritize these developments This context motivated our team to undertake the project titled "Research, Design, and Fabrication of an Automatic Macadamia Nut Shelling Machine," aiming to make a meaningful contribution to the advancement of our nation's industry.
Survey some macadamia nuts shelling machine on the market
2.5.1 Shelling macadamia nuts by manual method
Figure 2.17: Mini macadamia nuts punching table
The macadamia nut cracker operates by placing the nut into the U-shaped groove and turning the handle, which activates the movable rod to apply pressure This pressure cracks the shell of the macadamia nut, producing a distinct clicking sound, after which the shell can be easily removed.
+ Compact design, easy to use, quick operation + Low investment cost, only about 900.000 VND
+ Low productivity, only suitable for small and medium-sized households
Figure 2.18: Macadamia nuts shelling by flywheel
(1) Grooving tool (2) Jaw position (3) Flywheel
The macadamia nut cracking process involves placing the nuts in the jaw position, securing them with one hand, and turning the flywheel with the other hand As the flywheel is turned, the grooving tool descends, effectively cracking the macadamia nuts.
+ Compact design, easy to use and operate
+ Create fine cracks, with kernel intact and aesthetically pleasing
+ Low productivity, about 40-70kg/day only suitable for small and medium scale
+ Requires experience to create fine cracks that kernel do not separate from the shell
2.5.2 Semi – automatic macadamia shelling machine
Figure 2.19: Macadamia nuts sheliing machine MSU-MAC[13]
+ Input: dried macadamia nuts with sizes from 21-30 (mm)
Figure 2.20: Working principle diagram machine MSU-MAC
+ Simple structure, suitable for small and medium scale
+ The rate of unshelling macadamia nuts accounts for a significant proportion, about 10% + It takes a time to sort shells and kernels
2.5.3 Automatic macadamia nuts shelling machine
❖ Macadamia nuts shelling machine HUK
Figure 2.21: Macadamia nuts cracking machine HUK
(1) Feeding hopper (4) Finished product container
+ Inlet: dried macadamia nuts with sizes from 22–26 (mm)
The macadamia nut processing begins with the nuts being fed into a hopper, where they drop into a cracking mechanism featuring two rollers that rotate in opposite directions to break the nuts apart Following this, the separated kernel and shell move along a horizontal conveyor for sorting, with the kernels directed into a finished product container while the shells are expelled.
+ Have conveyors for sorting kernels and macadamia shells
+ Simple structure, easy to manufacture
+ The macadamia kernel is broken after shelling
❖ Macadamia nuts shelling machine Model MH4D-2S
Figure 2.22: Macadamia nuts shelling machine TOTRA Model MH4D-2S
(1) Feeding hopper (4) Cylinder (7) Belt cover
+ Inlet: dried macadamia nuts with sizes from 21,5–23,5 (mm)
Figure 2.23: Working principle diagram machine TOTRA Model MH4D-2S
+ High productivity (80kg/h), suitable for medium and large processing facilities
+ Macadamia nuts in a certain size range: 21.5–23.5 (mm)
+ The macadamia kernel is broken.
Limitation of existing machine on the market
- Synchronization of feeding mechanism with transmission parts is not optimal
- Can only shelling nuts within a certain size range
- The macadamia kernel is broken
- The cost is too high for small and medium processing facilities
2.6.2 Ways to solve the limitation
- Design mechanism to synchronize the feeding hopper with transmission parts
- Shelling macadamia nuts with a wide range of sizes by calculating, selecting springs suitable for many sizes of macadamia nuts
- Shelling according to the profile of macadamia nut so that kernels don’t break
- Low cost to meet for small and medium processing facilities.
THEORETICAL BASIS
Research about the feeding mechanisms used in machines on the market
Production systems are increasingly embracing automation to enhance stability and efficiency A critical aspect of this development is the precise spatial positioning of workpieces throughout the machine's operating cycle Consequently, optimizing the feeding process is essential for automatic production systems, as it directly impacts labor productivity, maximizes the utilization of machines and equipment, and ultimately improves product quality.
- Workpiece type: macadamia nut is considered workpiece with a center of symmetry Based on table 12.1 [2], macadamia nut is classified as type 0
+ Tubular feeding mechanism by round-trip reciprocating motion[2]:
Figure 3.2: Tubular feeding mechanism Principle: after putting nuts into the feeder, macadamia nuts will fall into slot, the rod (2) will move to the cutting parts
Figure 3.3: Chain feeding mechanism Principle: after putting nuts into the feeder, nuts will falls into slot on chain, then chain is driven to the cutting parts
The mechanism operates by placing nuts into the hopper, where a disc, driven by worm gears, begins to rotate As the disc slot reaches its lowest position, the nuts drop into the slot, and once the slot ascends to the highest point, the macadamia nuts are released.
Figure 3.5: Drum-type feedding mechanism
The process begins with macadamia nuts being placed into the hopper, where they then cascade into the designated empty boxes on the rotating disk As the drum-disc rotates, the nuts are efficiently funneled down into the transmission section, ensuring a smooth and organized flow of the nuts throughout the system.
Research mechanisms to synchronize with the feeding mechanism
The slider-crank mechanism is composed of three essential parts: a crank, a connecting rod, and a slider The crank acts as a rotating shaft powered by a driven pulley The connecting rod serves as a linear link that connects the crank to the slider, while the slider functions as a sliding element that moves back and forth in a straight line.
A ratchet mechanism is a mechanical device designed to enable continuous linear or rotary motion in one direction while blocking movement in the opposite direction This mechanism operates using a wheel with notched teeth and a pawl that engages with the wheel as it rotates, ensuring unidirectional movement.
The Geneva mechanism converts the continuous rotation of a drive wheel into the intermittent rotation of a driven wheel This mechanism features a pin on the rotating drive wheel that engages with a slot on the driven wheel, advancing it incrementally with each rotation Additionally, an elevated circular blocking disc on the drive wheel secures the driven wheel in place between movements, ensuring precise step-wise advancement.
Learn about finite element analysis method
The Finite Element Method (FEM) is a widely used numerical technique for solving partial differential equations in two or three dimensions It works by breaking down complex systems into smaller, manageable components known as finite elements through a specific spatial discretization process, which involves creating a mesh of the object This mesh serves as the numerical domain for the solution, consisting of a finite number of points Ultimately, the FEM formulation of a boundary value problem yields a system of algebraic equations that approximates the unknown function across the domain The individual equations representing these finite elements are then combined into a comprehensive system that encapsulates the entire problem.
- Use this method to analyze the cutpath profile of the macadamia nut, as a basis for the design process.
DIRECTION AND SOLUTIONS
Introduce about CODIA Industrial Solutions Co., Ltd
CODIA Industrial Solutions Co., Ltd is a specialized mechanical workshop dedicated to producing applied mechanical products that address technical support needs in everyday life The company effectively targets household customers and production facilities, enabling seamless collaboration and fostering contributions to establish a centralized support system for machinery in business and production environments.
Figure 4.1: Logo of CODIA CO.Ltd
The company is currently developing a processing line for macadamia nuts, which includes several key stages: dehusking, drying, and shelling A dedicated team has been assigned to focus on the design and research of an automatic macadamia nut shelling machine that meets the company's technical requirements.
Design requirements
To ensure stable operation and compliance with company standards, a macadamia nuts shelling machine must fulfill specific requirements.
- Shelling the sizes of macadamia nuts from 25-30mm after measuring in section 2.4.1
- Kernel of macadamia nuts is intact
- Compact machine, removable parts for easy maintenance and repair
- Meet the initial productivity set out at 80kg/h
- Smooth operation, low noise and vibration
- Reasonable cost, under 25 million VND.
Design process of automatic macadamia nuts shelling machine
Figure 4.2: Principle diagram of macadamia nuts shelling machine.
Design options
(1) Cluster of Cylinder (7) Rod containing hole
(2) Cluster of Cylinder (8) Cluster of Cylinder
Figure 4.4: Principle diagram of option 1
(4) Rod containing holes (12) Tranmission parts
(7) Slider crank (15) Cutpath profile rod
Figure 4.6: Principle diagram of option 2
Analysis and selection of option
Figure 4.7: Feeding hopper for each line
Advantages - Grant macadamia nuts continuously for each line
- Control macadamia nuts to be in the desired position
- Easily synchronize with the next parts
- Grant macadamia nuts continuously for each line
- Can give nut in large quantities at the same time, without causing jam
Disadvantages - Make noise when operating
- Macadamia nuts can get stuck
- Difficultly calculate to synchronize with other parts
Table 4.1: Advantages and disadvantages of feeding hopper options
Figure 4.10: Transmission by slider – crank mechanism
- Select the cylinder stroke according to the standard
- Operate quietly, make noise less
- The ability to generate is not great
- Difficult to install, takes up a lot of space
- Periodic maintenance is required Table 4.2: Advantage and disadvantage of transmission part options
Figure 4.12: Clamp by V-block and spring
- Firmly clamp, nuts don't fall out during operation
- Can clamp nuts of different sizes thanks to the spring
Disadvantage - Macadamia nuts can fall out
- Only clamp macadamia nuts in a certain size range
- Difficult to calculate the compressive strength of the spring
Table 4.3: Advantage and disadvantage of fixed part options
Figure 4.13: Nuts shelling by grooving tools
Figure 4.14: Nuts shelling by hacksaw blade
Advantage - High nuts shelling rate - The kernel is intact, in accordance with the requirements
- Can cut nuts with many sizes
Disadvantage - Only macadamia nuts shelling in a certain size range
- High kernel breaking rate, don't match requirements
- Difficulty in design of toolpath profile rod
Table 4.4: Advantage and disadvantage of cutiing part options
Selection of optimal plan
After analyzing advantages and disadvantage of two options, we chose option 2 instead of option 1 because of several reasons:
- Can cut macadamia nuts with a wide range of sizes ( 25-30mm)
- Low breaking kernel rate, suitable for customer needs
- Low cost, suitable for small and medium processing facilities
- Operate quietly, make noise less compared to option 1
Figure 4.15: Main parts of macadamia nuts shelling machine.
Implementation process
- Learn and refer to relevant machines and mechanisms on the market
- Connect electrical and mechanical systems
CALCULATION, DESIGN OF MECHANICAL ELEMENTS
Calculation, design of geneva mechanism
Figure 5.1: Geneva Mechanism Calculating the components of geneva mechanism
- With roller containing 4 rows of holes, we need to calculate the geneva mechanism with the number of slots: Z = 4
➔ The motionable coefficient of geneva mechanism [4]: k = t 1 t 2 =(π − 2π/Z)
4 Therein: t 1 : is the time it takes for complete 1 revolution of pin t 2 : is the time it takes for complete 1 revolution of driven wheel
➔ Movement time of driven wheel is euqal 1/4 of down time
- Angle between the 2 slots for pin:
- RPM of the rotating drive wheel n 1 : n 1 = 4 n 2 = 4.10 = 40rpm
- Radius of drive wheel r 1 (O 1 C)5mm
- Constan angular velocity of drive whell: ω 1 =n 1 π
- Slot depth on driven wheel
- In order to rotating dirve wheel , pin doesn't get stuck in slots: choose C t = 90mm
Figure 5.3: Design of drive whell
Figure 5.5: Design of driven wheel
5.1.1 Calculate the force required for rotating drive wheel
Figure 5.6: Application force of drive whell
- Mass of drive whell m 1 = 5,3kg
- Radius of drive wheel r 1 (O 1 C)5mm
- Angular acceleration of drive wheel: ε 1 = r ω 1 2 = 0,135 × ( 4
- Force required to rotate drive wheel:
5.1.2 Calculate the force required for rotating driven wheel
- Considering any position of the mechanism, then the crank O 1 A and slot O 2 A of the drive wheel create with center distance O 1 O 2 the angles are φ 1 and φ 2 respectively
Mass of driven whell and roller m 2 7kg
Table 5.2: Specifications of driven wheel Based on document[5]
- Therein: λ = r l = sinφ2 sin(180 0 − φ2 − φ 1 ) = sinφ2 sin (φ 1 + φ 2 )
- Angular velocity of driven wheel: ω 2 = ω 1 λ(cosφ 1 − λ)
- Drive wheel rotate evenly (ω 1 = const) so angular acceleration of driven wheel is calculated by the formula: ε 2 = ω 1 2 sinφ 1 (1 − λ 2 )
- Convert angular acceleration to acceleration in linear motion: ε 2 = 11,65.0,12 = 1,4m/s 2
- Force required for pin of drive whell:
Caculation, design of slider-crank mechanism
The actuator is designed based on the slider crank mechanism
The stroke from feeding position A to chute C measures 190mm, necessitating a crank design with a length of 95mm between its two joints This design includes one hole compatible with a shaft of diameter ∅20mm and another hole suitable for a bearing with a diameter of ∅26mm.
- Choose fits of ball bearing with crank hole in rotating conditions:
+ Radial load acting on a ball bearing with constant direction
+ Point load on inner ring
=> Rotating inner ring load , stationary outer ring load
+ Shaft and inner ring fits: tolerance zone k6
+ Housing and outer ring fits: tolerance zone G7
5.2.2 Calculation, design of conecting rod
The connecting rod length is determined by the distance from the feeding position to shaft I, measuring 105mm, in conjunction with the crank length of 95mm Consequently, the distance between the two joints of the connecting rod is 200mm, with both joints designed to fit an outer bearing ring of 26mm in diameter.
- Choose fits of ball bearing with hole 1 in rotating conditions:
+ Radial load acting on a ball bearing with constant direction
+ Point load on inner ring
=> Rotating inner ring load, stationary outer ring load
+ Shaft and inner ring fits: tolerance zone k6
+ Housing and outer ring fits: tolerance zone G7
- Choose fits of ball bearing with hole 2 in rotating conditions:
+ Radial load acting on a ball bearing with constant direction
+ Point load on outer ring
=> Rotating outer ring load, stationary inner ring load
+ Shaft and inner ring fits: tolerance zone g6
+ Housing and outer ring fits: tolerance zone M7
Figure 5.10: Design of conecting rod
5.2.3 Calculate the force required for slider – crank mechanism
Figure 5.11: Force resolution of slider – crank mechanism in case α0°
Conecting Rod: m 2 = 0,35 kg, BC 0mm
Slider: m 3 = 5,2 kg, AC is horizontal and D is midpoint of rod BC
*Consider the friction force between double liner bearing and liner rails to be negligible
- BC moves plane-parallel, choose B as the pole: v
⃗ B ⊥ AB, in the same direction ω 1 v
⃗ CB ⊥ BC, (dimensional hypothesis) Table 5.3: Velocity values and direction of points
- Choose scale of the chain to plot the velocity plan: μ v =v B
Angular velocity of rod 2 (conecting rod BC): ω 2 =v CB
ω 2 in the same direction v CB
- Velocity of point D: applying the fundamental theorem of similarity, D is the midpoint of BC Measure pdp,91 mm
- Acceleration problem: BC moves plane-parallel, choose B as the pole: a⃗ C a⃗ n B a⃗ τ B a⃗ τ CB
BC.ε 2 (Acceleration of conecting rod)
C to B a⃗ CB τ ⊥ BC,(dimensional hypothesis)
Table 5.4: Acceleration values and direction of points
- Choose scale of the chain to plot the velocity plan: μ a = a B n
- Angular acceleration of conecting rod (conecting rod BC): ε 2 =a⃗ τ CB
=> ε 2 in the same direction with a⃗ τ CB
- Acceleration of point D: applying the fundamental theorem of similarity, D is the midpoint of
Linkage 1 (AB) Linkage 2 (BC) Linkage 3 (liner C)
- The mass moment of inertia of linkage1: (considering linkage 1 as straight rod)
- The mass moment of inertia of linkage2: (considering linkage 2 as straight rod)
- Separation of static cluster, linkage in the cluster, apply force on linkages:
Figure 5.14: Application force diagram of atxua cluster 2
- Force balance equation for the atxua cluster:
- Considering linkage BC, moment equilibrium equation at C: ΣM C = 0 ⇒ R τ 12 =M 2 − G 2 CDsin76° + F 2 CDsin28°
From equation (1), solve by force plan method with the force scale μ = 100N mm
⇒ M cb = R 12 AB sin57° + G 1 (0,5 AB cos30°)
- In order to linkage AB operates, so F cb >10,8 N
Caculation, design of cutting parts
- The cutting parts is designed with 6 saw blades located in 6 positions corresponding to the midpoint of each hole on the rod
To efficiently remove excess workpieces from macadamia nut shells, it is essential to use a straight saw tooth type blade This design ensures a clean cut, maximizing engine power and enhancing overall performance.
- Choose saw blade T40 Bosch with parameters:
- Based on the formula in the document [7] :
F: cutting force on hacksaw blade
H: macadamia nuts shell thickness, H=3mm
- Cutting force on 1 hacksaw blade:
- Cutting force on 6 hacksaw blade:
Calculation, design of shaf
- Material for the shaft is made of C45 steel after quenching, tensile strength σ b = 750 Mpa, yield strength σ ch = 450 Mpa
5.4.2 Determineation of load acting on the object
+ Tangent force acted by pulley: F t = 428,6N
+ Force acted by crank: : F t cr = 341,8N
+ Tangent force acted by drive wheel: F tdw = 270,6N
+ Tangent force acted by driven wheel: F tdw2 = 166,5 N
5.4.3 Preliminary determination of shaft diameter:
= 16,5mm Choose [τ] = 22Mpa for shaft II d 2 ≥ √ T 2
5.4.4 Determination of bearing distance and force points:
The shaft length and the distance between the shaft bearings and force points are influenced by various factors, including the dynamic scheme, the length of the wheel hub in the rotating parts, the width of the shaft bearings, and the required clearance.
- Choose the distance of shaft bearing based on machine frame
Figure 5.19: Transmission diagram of motor to shaft I and II
5.4.5 Determination of the value and direction of forces
- Choose coordinate system as shown in the figure:
Figure 5.21: Diagram of application force for shaft I
- Determine force value of both shaft bearings acting on the shaft I:
- Force balance equation: ΣF x = F x 11 + F x 12 + F t đ − F t bd − F t tq = 0
Figure 5.22: Moment diagram of shaft I
Figure 5.19: Diagram of application force for shaft II Determine the force value from 2 bearings acting on the shaft: ΣM x A ⁄ = 0
Figure 5.20: Moment diagram of shaft II
Calculate the total bending moment M j and equivalent moment M tđj at the cross-sections of the shaft length:
Table 5.6: Result of calculating total moment at the cross-sections
- Calculating of shaft diameter at the cross-sections j:
[σ]: Allowable stress of fabricated steel Based on table 10.5 [8], choose [σ]c Mpa
+ Torque on shaft III: 1370 (N mm)
- Tangent force of the coupling acting on the shaft causing the torque T is determined:
Figure 5.25: Diagram of application force for shaft III Determine the binding reaction force: ΣM x A ⁄ = 0
Figure 5.26: Moment diagram of shaft III
- Strength test for shaft subjected to simultaneous torsion and bending:
+ Shaft is made of steel with [σ] = 12 kN/cm 2
- Equivalent moment at postion 3 according to theory of strength 4 σ max tb4 (√M x 3 2 ⁄ + M y 3 2 ⁄ + 0.75M Z 2 )
⇔ d ≥ 0,7 cm d3 mm ≥ 7 mm, satisfy durability condition
5.4.6 Examination of shaft for fatigue strength
- Material for the shaft is made of C45 steel after quenching, tensile strength σ b = 750
- Bending stress varies with the period of symmetry, based on formula 10.22 [8]: σ mj = 0; σ aj = σ maxj =M j
- The shaft rotates in 1 direction, so the torsional stress changes with the dynamic circuit period, based on formula 10.23 [8]: τ mj = τ aj =τ maxj
2W oj (MPa) Looking up table 10.6 [8]:
- Calculate value modulus of section ad torsion:
20 = 1570,8 (mm 3 ) ψ σ và ψ τ : coeficient take into account the influence of the average stress value on the fatigue strength, looking up table 10.7[8]: ψ σ = 0,1 (MPa) and ψ τ = 0,05 (MPa)
K σdj and K τdj : based on formula 10.25 và 10.26 [8]:
Or table 10.12 [8] , use end mill:
K τ = 1,65 ε σ , ε τ : dimensional coeficient takes into account the influence of the shaft cross-sectional dimensions on the fatigue limit 10.10[8]
Section Diameter d, (mm) B x h t 1 W j (mm 3 ) W oj (mm 3 ) ε σ ε τ
Table 5.7: Calculation parameters on each position of shaft
K x : stress concentration coefficient due to surface state Shaft is machined on a lathe with roughness R a 2,5 ÷ 0,63 Based on 10.8 [8], choose K x = 1,1
K y : durable increase coeficient of shaft surface Choose K y = 1
K σd K τd S σ S τ σ aj τ aj S key way drive fit key way drive fit
Table 5.8: Results of shaft strength caculation
⇒ All shafts at hazardous cross-sections pass the fatigue test of the shaft
5.4.7 Examination of shaft for static strength
⇒ So the shaft satisfies the condition of static strength
Diameter of shaft segment at positions A, B, C, D, E
DA,B, C, D,E (mm) DA = dB = dC = dD (mm)
Safety coeficient of shaft sj sj = >[s] = 2
Static strength of shaft td (MPa) σ td = 40,7 < [σ] = 360 (MPa)
Table 5.9: Calculation results of shafts for static strength
5.4.8 Examination of feather key for strength
For cross-sections using key joints, we conduct joint tests on stamping strength σ d and shear strength τ c :
- With l t = 1,35 d, type feather key, [τ c ] = 40 ÷ 60Mpa, [τ c ] = 100Mpa Choose the length of feather key in table 9.1[8]
❖ For shaft I: l tA = l tB = l tE = 1,35 d = 1,35 20 = 27 mm
Choose by standard l tA = l tB = l tE = 28 mm σ A = σ B = σ E = 2 T A d A l tA (h − t 1 )= 2 16235
20 28 (6 − 3.5) = 23,19 (Mpa) τ cA = τ cB = τ cE = 2 T A d A l tA b=2 16235
20 28 6 = 9,67 (Mpa) Cross- Section d (mm) l t (mm) bxh t 1 T (N.mm) σ d (Mpa) τ c (Mpa)
- According to table 9.5 [8], with static load in fixed fit type:
So the key joints are guaranteed for stamping strength and shear strength
❖ For shaft II: l tA = 1,35 d = 1,35 20 = 27 mm, choose l tA = 28 mm σ A = 2 T A d A l tA (h − t 1 ) = 2 16235
Section d (mm) l t (mm) bxh t 1 T (N.mm) σ d (Mpa) τ c (Mpa)
Table 5.7: Results of feather key test calculation for cross-sections of shaft II
- According to table 9.5 [8], with static load in fixed fit type
So the key joints are guaranteed for stamping strength and shear strength
5.4.9 Calculation and selection of bearings
F r = 0 ≤ 0,3, F a = 0 (because drive wheel has no axial force)
- Therefore, we choose single row radial ball bearing for the shaft bearings at positions C and D of shaft I
- Based on shaft diameterd C = d D = 20 mm Looking up table P2.7 [8] choose a small-sized radial ball bearing with symbol 204
Symbol d (mm) D (mm) B (mm) r (mm) Bi (mm) C (kN) C o (kN)
Table 5.8: Specification of radial ball bearing with symbol 204
- Test the ability to withstand dynamic loads
Radial load acting on the bearing at C:
Radial load acting on the bearing at D:
So we test with the largest load bearing at C:
Based on 11.3 [8], with single row radial ball bearing:
+ F r , F a : Radial load and axial load
+ V: coefficient takes into account inner ring or outer ring rotates; when the inner ring rotates V
+ k t : coefficient takes into account influence effect of temperature, choose temperature θ ≤ 105℃, Kt = 1
+ k đ : coefficient takes into account the characteristic of the load, based on table 11.3[8] provided that the static load k đ = 1
+ X: radial load coefficient, for radial ball bearing X = 1
+ Y: axial load coefficient, for radial ball bearing Y=0
- Substitute into the above formula:
+ L: lifetime is measured in million revolutions
+ m: fatigue curve tier in ball bearing test, for radial ball bearing m = 3
Number of rotational speed on shaft II: n = 40 v/ph
Thus, dynamic load capacity of the bearing is guaranteed
F r = 0 ≤ 0,3, F a = 0 (because driven wheel has no axial force)
- Therefore, we choose single row radial ball bearing for the shaft bearings at positions B and C of shaft II
- Based on shaft diameter d B = d C = 20 mm Looking up table P2.7 [8] choose a small-sized radial ball bearing with symbol 204
- Test the ability to withstand dynamic loads
Radial load acting on the bearing at B:
Radial load acting on the bearing at C:
So we test with the largest load bearing at B:
Based on 11.3 [1], with single row radial ball bearing:
- Substitute into the above formula:
Dynamic load capacity is calculated based on formula 11.1[8]:
Number of rotational speed on shaft II: n = 40 v/ph
Thus, dynamic load capacity of the bearing is guaranteed
F r = 0 ≤ 0,3, F a = 0 (because hacksaw balde has no axial force)
- Therefore, we choose single row radial ball bearing for the shaft bearings at positions A and B of shaft III
- Based on shaft diameter d A = d B = 20 mm Looking up table P2.7 [8] choose a small-sized radial ball bearing with symbol 204
Radial load acting on the bearing at C:
So we test with the largest load bearing at A:
Based on 11.3 [8], with single row radial ball bearing:
- Substitute into the above formula:
Dynamic load capacity is calculated based on formula 11.1[8]:
Number of rotational speed on shaft II: n = 1500 v/ph
Thus, dynamic load capacity of the bearing is guaranteed.
Caculation,design of belt drive
When selecting a V-belt for driving from a motor to shaft I, it's essential to choose one with a trapezoidal cross-section This design allows for two sides of the belt to make contact with the corresponding grooves, resulting in a higher coefficient of friction compared to flat belts Consequently, V-belts offer greater pulling capacity, making them ideal for applications where speeds are typically below 25 m/s.
Figure 5.27: Cross-section of V-belt Because of small transmission power P = 0.09kW, so choose V-belt type O
Table 5.13: Cross-section of type O
5.5.2 Determine parameter of belt drive
+ Based on table 4.13 [8], choose d 1 = 100 mm
1 − 0.01 = 101,01 mm Choose d2 = 100 mm Choose driven pulley diameter according to standard [8]
Trong đó: u=1: Gear ratio from motor to shaft I ε = 0,01 : slip coefficient
- Thus, the ratio deviation is within the allowable range
5.5.4 Calculation of preliminary center distance
- The center distance is calculated by the formula 4.14 [8]:
- The belt length is calculated by the formula 4.4 [8]: l = 2a +π(d 1 + d 2 )
- Chọn l = 800 (mm) based on table 4.13 [8]
- Lifetime examination of belt by formula 4.15 [8]: i =v l = 0,21
∆= 0 Thus, center distance a is still within the allowable value
+ P 1 : power on drive pulley, P 1 = 0,09kW
+ K đ : for static load and single-phase electric motor Choose K đ = 1, table 4.7
+ [P 0 ]: permissible power with v=0,2 m/s, d10mm, belt type O
Choose [P 0 ] = 0,46 kW, looking up table 4.19
+ C α : coefficient takes into account influence of the hug angle α 1 = 180°
+ C l : coefficient takes into account the effect of belt length
+ C z : coefficient takes into account the effect of uneven load distribution on the belts Choose C z = 1, table 4.18
- Based on formula 4.18 [8]: d a = d + 2h 0 Drive pulley: d a1 = d 1 + 2h 0 = 100 + 2.2,5 = 105mm Driven pulley: d a2 = d 2 + 2h 0 = 100 + 2.2,5 = 105mm Therin: with belt type O, look up table 4.21[8]
5.5.10 Determine the initial tension and force acting on the shaft
- Tension of 1 belt is determined by formula (4.19) [8]:
F v = q m v 2 = 0,061 0,21 2 = 0,002N: Tension caused by centrifugal force (periodic tension adjustment), based on formula (4.20) [8]
+ q m = 0,061 (kg/m): weight of 1meter belt length, table 4.22 [8]
+ P 1 = 0,09 (kW): power of drive pulley
- The radial force acting on shaft is calculated by the formula 4.21[8]:
Power of drive pully P 1 (kw) 0,09
Diameter of drive pulley d 1 (mm) 100
Diameter of driven pulley d 2 (mm) 100
Caculation of power motor
1000 = 7,12 10 −3 kW + Pin of drive wheel:
- Power of slider – crank mechanism :
- Transmission efficiency: η 1 = η đ η ol 2 = 0,96 0,99 2 = 0,94 η 2 = η geneva η ol 2 = 0,9 0,99 2 = 0,88 Therein: η geneva = 0,9 Looking up table 13.a[14]
0,94 = 7,6 10 −3 (kW) + Pin of drive wheel:
P ct = P ct1 + P ct2 + P ct3 = 7,6 10 −3 + 2,6 10 −3 + 6,4 10 −3 ≈ 0,02kW
- Based on the necessary power of motor, choose motor with parameters:
Therein: u: is overall gear ratio u d : gear ratio of belt drive u geneva : gear ratio of geneva mechanism
- Rotational speed on working shaft: n dc = 40v/ph + Shaft I: n 1 =n dc u 1 @
- Because the intermittent rotation of the driven wheel is caused by the drive wheel:
Table 5.15: Statistics table of Shaft I and II
Parameters Motor Shaft I Shaft II
1000 = 0,18kW Therein: v 4 is the cutting speeed of hacksaw blade, v 4 = 5 (m/s)
+ Motor has highly rotational speed (1500rpm) to smoothly cutting
+ Because shaft 3 moves up and down so a compact motor mass is required
- Gear ratio distribution: u 3 =n dc n lv 00
Therin: u nt is gear ratio of coupling
- Rotational speed on working shaft: n 3 =n dc u 3 = 1500rpm
Table 5.16: Statistics table of shaft III
Calculation, design of feeding hopper
5.7.1 Calculation, design of feeding roller
- In order for the feedding roller to synchronize with geneva mechanism, rotation angle of
2 consecutive times on the roller must be equal to the angle between the two slots of the driven wheel, with a value is 90°
- So feeding roller is divided into 4 rows, each row has 6 holes, each hole has a diameter of
∅35mm and a depth of 25mm
Figure 5.21: Design of feeding roller
- In order for feeding hopper to work synchronously with transmission parts, the keyway of drive whell must rotate before keyway of the slider-crank mechanism by an angle of 90°
The shelling machine is capable of processing 11,200 nuts per hour, and its feeding hopper is designed to accommodate approximately 25,000 nuts, allowing for two hours of uninterrupted operation.
Macadamia nuts are classified as type 0, meaning their natural orientation eliminates the need for additional positioning With an average radius of 14mm, the volume of macadamia nuts can be calculated using the formula for the volume of a sphere.
- The volume of feeding hopper that can hold the number of macadamia nuts for more than
Figure 5.23: Measure the volume of feeding hopper
Calculation, design of fixied parts
Figure 5.25: Diagram of applycation forces on macadamia nuts
Applied force Unit Reaction force N (N) Thrust force P (N) Friction force Fms (N) Elastic force Fdh (N) Table 5.9: Components of the applied force
- Forces projecting in the vertical direction:
- Considering case that generates the largest friction force caused by the POM plastic as sliding friction:
2 sinα 2 Therein: f is sliding friction coefficient, with POM plastic f = 0,04 [9]
- Calculate the maximum elastic force when cutting macadamia nuts:
Therein: ∆L =D max O − D min O = 30 − 25 = 5mm k: is the stiffness of the spring (N/mm)
- Conditions for macadamia nuts to move in the V-block:P>2 Fms
Choose springs according to TCVN 2022-77 standard with following parameters[17]:
Stiffness of the spring (k): 27,22N/mm
Table 5.10: Main parameters of spring
The lower V-block is designed to support and guide the macadamia nuts as they fall from the feeding roller to the cutting part
Figure 5.27: Design of lower V-block
The upper V-block effectively grips macadamia nuts securely, utilizing the spring's elastic force to adjust its position for various nut sizes.
Figure 5.28: Design of upper V-block
Design toolpath profil rod
- Using method of finite element analysis to design the macadamia nut cutpath profile
Figure 5.29: Finite element analysis to design cutpath profile by Autocad 2021
- Simulation of cutting process according to macadamia nuts profile
Figure 5.30: Simulation of saw blade positions by Inventor 2021
Figure 5.31: Design of cutpath profile rod
Calculation and testing of frame strength
- Choose material: square steel tube 30x30x1,8mm
- Steel bars are connected by welding
- Measure the volume of parts by using Inventor 2021 software:
+ Total mass supported by the frame: 64,7 kg
So the biggest bearing bar is 2 bars supporting cutting part, team needs to calculate the bearing capacity here
- We need to calculate and test under the following conditions: σ max k =M x max y k max
+ Tensile and compression stress of steel CT3: 373-461 N/mm 2 [10].
- Considering the part of the bar that is subjected to the greatest load
- Determine the binding reactions in the yOz ΣM y A ⁄ = 0
Figure 5 33: Moment diagram of the largest bearing bar
Figure 5.34: Strength parameters for cross-section
- Moment of inertia Jx: 27021 mm 2
- Testing of frame strength y k max = y n max σ max k = σ max n =M x max y k max
27021 = 8,95 (N/mm 2 ) Comparing with tensile and compressive stress for steel of CT3 material, we get the results:
- Test strength of frame by Inventer 2021 software:
Figure 5.35: Test of stress and displacement
- Conclusion: maximum stress on the bar is 8.96 Mpa < σmax ≈ 373 Mpa Frame is durable enough to support the weight of other parts.
FABRICATION AND EXPERIMENT
Fabrication of frame
- Manufacturing process: cutting, welding the bars together, grinding, painting
- Material: square steel tube 30x30x1,8mm
- Requirements when manufacturing: ensure parallelism and perpendicularity between the support bars on the frame
Figure 6.1: Detail drawing of frame
Figure 6.2: Fabrication process of frame
Fabrication of feeding hopper
+ Manufacturing process: laser cutting, sheet metal bending
+ Material: steel plate with thickness 2mm
Figure 6.4: Detail Drawing of hopper
Figure 6.6: Detail drawing of feeding roller
Fabircation of fixing parts
+ Manufacturing process: laser cutting, sheet metal bending
+ Material: steel plate with thickness 5mm
Figure 6.8: Detail drawing of support rods
+ Machining process: manufacturing of V-block cluster by CNC machine
Figure 6.9: Programing V-block by Creo Prametric 8.0 software
Figure 6.10: Fabrication of V-block cluster by CNC machine:
- Assembly of upper V-block cluster:
Figure 6.11: Realistic upper V-block cluster
- Assembly of lower V-block cluster:
Figure 6.12: Realistic lower V-block cluster
Fabrication of shaft and bushing
Figure 6.14: Detail drawing of shaft III
Figure 6.15: Fabrication process of shaft and bushing
Figure 6.16: Realistic shaft and bushing
Figure 6.17: Assembly of realistic cutting parts
Fabrication of support rod
Figure 6.18: Detail drawing of vertical support rod
Figure 6.19: Detail drawing of horizonal support rod
Figure 6.20: Fabrication process of shaft and bushing
Fabrication of chute
- Manufacturing process: laser cutting, sheet metal bending
- Material: steel SPC with thickness 2mm
Figure 6.21: Assembly drawing of chute parts
Design of controller system
Table 6.1: Device statistics table in the controller system
No Images Device name Function Qty
- Protect an electrical circuit from damage caused by overcurrent
- Interrupt current flow to protect equipment and to prevent the risk of fire,…
3 Speed control Adjust motor speed 1
4 Emergency stop push button Emergency stop 1
5 Green push buttuon switch Starting a machine 1
Indicates that the power system is operating normally
7 Red push buttuon switch Stopping a machine 1
Indicates that the electrical system is not operating
Automatic adjustment, safety protection, and conversion circuit
10 Electrical enclosure Contains electrical device 1
Conduit fittings Protect conductors from sharp objects 3m
Table 6.2: Input and Output signals of electrical system
Green push buttuon switch Motor operateing
Red push buttuon switch Motor stop operating
Emergency stop push button Emergency stop
- Close the CB to power the system
- Press the Start button, Relay K is powered:
+ Close the normally open contacts K at line 2 to maintain the circuit
+ Close the normally open contact K at line 3 to Green light is on
+ Close the normally open contact K in the dynamic circuit to power the motors M1 and M2 to operate
+ At the same time, open the normally closed contact K at line 4, and the red light stops
- Press stop push button, Relay K loses power:
+ Contacts return to their original state
+ Engine M1 and M2 stop working and at the same time Red light is on
- Press the E-stop push button: stop powering the system.
Finishing machine
Figure 6 25: Design model in Inventor 2021
Experimental running of automatic macadamia nuts shelling machine
- Purpose: evaluate the realistic results of the machine compared to the original goal set out
+ Automatic macadamia nuts shelling machine
+ Dried macadamia nuts purchased in DakLak province
+ Step 1: Inspect and clean parts before operation
+ Step 4: Turn on the machine operation switch
Table 6.3: Result statistic table of the 1st experiment (𝐧 𝐝𝐜 %rpm)
No Number of macadamia nuts
With motor's rotational speed 25rpm, shelling efficiency is high, but intact kernels efficiency is not satisfactory
Table 6.4: Result statistic table of the 2nd experiment (𝐧 𝐝𝐜 @rpm)
No Number of macadamia nuts
With motor's rotational speed of 40rpm, shelling efficiency meets the set requirements and broken kernel efficiency is low
Table 6.5: Result statistic table of the 3rd experiment (𝐧 𝐝𝐜 Urpm)
No Number of macadamia nuts
With motor's rotational speed of 55rpm, broken kernel efficiency is low, but shelling efficiency as well as low, less than 80%
The rotational speed of the motor significantly influences both shelling efficiency and broken kernel efficiency A lower rotational speed enhances shelling efficiency, while simultaneously reducing intact kernel efficiency; conversely, increasing the speed improves intact kernel efficiency but decreases shelling efficiency.
Experimental results indicate that optimal outcomes are achieved at specific motor rotational speeds, aligning with business requirements as demonstrated in the statistical data table.
• Rotational speed of the motor: 40 rpm
+ Images when operation machine and experimental results:
Figure 6.28: Macadamia nuts fall in to holes on the feeding roller
Figure 6.29: Macadamia nuts fall in to holes in the rod
Figure 6.30: Macadamia nuts cut by hacksaw blade
Figure 6.31: Macadamia nuts before and after cutting
Figure 6.32: Sorting macadamia nuts after shelling Therein:
Type A: Macadamia nuts are cut without breaking kernel
+ Shelling efficiency: 82,7% > 80% => achieve the set goal (section 1.4.3)
+ Broken kernel efficiency:15,8% > 10% => failed to achieve the set goal (section 1.4.3)
+ Because of different mechanical properties and sizes of macadamia nuts
+ Periodic lubricate the transmission parts: once a week
+ Periodic replacement of saw blades as recommended by the manufacturer:every 3 months + Regularly lubricate bearing: every 2 weeks
+ Regularly clean the machine to ensure food safety for macadamia nuts
CONCLUSION AND FUTURE DEVELOPMENTS Conclusion:
During our research for the graduation thesis on "Research, Design, and Manufacture of an Automatic Macadamia Nuts Separator," our team gained valuable insights into market dynamics and the purchasing process for mechanical goods This project allowed us to engage in hands-on experience in designing agricultural machinery, enabling us to develop our own manufacturing processes and ensure that all parts met the necessary technical specifications.
With the guidance and enthusiastically support of advisor, along with our own efforts, we have completed the graduation project on time with the following results:
+ Survey macadamia nuts consumption market in domestic and foreign
+ Research method of shelling macadamia nuts on the market
+ Understand steps up the design process for a particular machine
+ Enhance skills in using 3D and 2D design software: Inventer, Creo, Autocad,…
+ Proficient in the use of all types of machines: welding machines, drilling machines, milling machines, lathe, etc
+ Have opportunity to use CNC milling machines to process parts, programmed by myself + Apply learned projects to calculate, design: belt transmission, slider-crank mechanism, geneva mechanism, key, shaft,
+ Using learned knowledge combined with software to simulate strength
+ Design of controller system+ Successful design and fabrication of macadamia nuts shelling machine
+ Nut shelling efficiency more than 80%
- Add 1 stage of size classification of macadamia nuts at the first step to ensure the shelling performance of the machine
- Create a taper between the 2 holes of feeding roller to make it easier for the macadamia nuts to fall into the hole
- Choose springs with suitable compression
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[15] U.S.Department of Agriculture, FoodData Central, Available: https://fdc.nal.usda.gov/, accessed 20/04/2023
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