59 Trang 19 1 CHAPTER 1: PROJECT OVERVIEW 1.1 Problem 60 years ago, servo motors revolutionized the motion control industry.. Chapter 2: Theoretical foundations Presenting theoretical
PROJECT OVERVIEW
Problem
Sixty years ago, servo motors transformed the motion control industry, and since then, their presence has expanded significantly across nearly all automatic control systems worldwide Ongoing advancements in science and technology have heightened the demand for precision and enhanced responsiveness in machines, essential for meeting the stringent requirements of modern automation systems Servo motors are now integral to various automated processes, including robotic arms, CNC machines, cranes, ball screw mechanisms, turntables, and linear systems.
The integration of science and technology has significantly transformed the world, leading to a modernized landscape Advances in automation technology have resulted in the creation of sophisticated production lines and equipment that deliver exceptional precision, speed, and responsiveness for complex manufacturing tasks In production systems, manual operations are often impractical for simultaneous tasks requiring exact movements; however, modern technology enables these processes to be executed with ease This necessity to understand device control and operational modeling inspired the selection of the topic "Synchronous Control in Flying Shear System."
Project goals
✓ Build a flying shear system model
✓ Communicate with devices included on models: Q00UJCPU, servo motor, DC brushless motor, motion CPU, CC-Link communication module
✓ Use the GX-Works 2 and GT Designer 3 programming software to synchronous control in Flying shear system
✓ Control flying shear system run in two modes: cut-to-length and cut-to-marker.
Researching methods
To effectively implement the topic, the group researched various online models, aligning their approach with the original objectives and specific details They utilized insights from previous courses and, most importantly, incorporated enthusiastic feedback from group instructors, who provided guidance on the direction and execution of the project.
✓ Refer to practice and teacher's instructions to come up with many ideas
✓ Research on servos and motion control
✓ Research on DC brushless motor and CC-Link network
✓ Tweak the system to achieve what you want
✓ Test run and get results
✓ Conclusion and drawing of shortcomings as well as future development direction.
Project limitation
Just stop at the simple synchronous motion application model.
Researching projection
➢ Assembly details such as flanges, base blocks, positioning pin holes, etc
➢ Motion controller CPU QD77MS16
➢ CC-Link communication module QJ61BT11N
➢ MR-J3-B servo motor connected via SSCNETIII
➢ LV-H35 high speed laser sensor and amplifier LV-21A
➢ Integrated PLS and High-speed mark detection I/F receiving port on QD77MS16.
Content of the subjects
This chapter presents the introduction problem, the reason for choosing the topic, objectives, research content, parameter limits and project layout.
THEORETICAL FOUNDATIONS
An overview of Flying Shear system
2.1.1 What is Flying shear in motion control
Motion control encompasses various applications that manage the movement of linear or rotary axes to reach specific positions or follow defined paths These applications can be categorized into several key types, including pick-and-place, positioning (both linear and rotary), path following (like dispensing), winding, and flying shear.
2.1.2 The function of Flying Shear
Flying Shears are essential tools for cutting continuously moving materials without interruption They ensure precise, "on-the-fly" cuts, maintaining accuracy even as the material remains in motion These devices feature a mechanical design that includes a saw or shear system mounted on a carriage, which synchronously follows the material during the cutting process Once the cut is completed, the carriage returns to its home position, ready for the next operation.
2.1.3 Cutting mechanisms of Flying Shear
There are two possible cutting mechanisms depending on the application requirements:
With parallel flying shears, the carriage travels in the same direction as the material
In this example, a shear cuts through material while the carriage and material move in sync After cutting, the shear raises and returns to its starting position to repeat the process The parallel mode is ideal for applications where the tool simultaneously operates across the entire width of the material, such as with punch tools or shears.
Figure 2 1: Parallel flying shear system
Angled flying shears operate by moving the saw at an angle to the material flow, with the carriage speed adjusted according to the angle of the shear This method is particularly effective for applications like saws and plasma-cutting tools, where the cutting tool must intersect the product flow at a right angle.
Figure 2 2: Angled flying shear system
An overview of AC servo system
A servo system, developed from frequency conversion technology, is an automatic control system that focuses on mechanical position or angle control Beyond just managing speed and torque, it excels in providing precise, rapid, and stable position control.
The generalized servo system is a control system that accurately tracks or reproduces a given process and can also be called a follow-up system
A narrow sense servo system, known as a position follow-up system, primarily controls the linear or angular displacement of a load machine's position Its main objective is to ensure that the output rapidly and accurately reflects any changes in the specified input quantity, allowing for precise tracking of positional adjustments.
The Driver Servo is an electronic amplifier designed to power servo motors by monitoring feedback signals from the servo mechanism It continuously adjusts any deviations from expected performance displayed on the operator's control screen, ensuring precise control and functionality.
The driver servo receives command signals from the control unit, processes and amplifies them, and transmits the signals to the servo motor, resulting in movement that corresponds to the commands Operators typically provide signals related to speed, position, or torque The recovery system sends these signals to the driver, which compares the current state with the command signal If the motor deviates from its intended position, the driver adjusts the frequency, speed, voltage, or pulse width of the servo motor to ensure precise alignment with the command signal.
When properly installed and controlled, a servo motor will rotate at a speed that closely matches the command signal received from the controller To optimize performance, key parameters such as hardness, damping coefficient, and recovery coefficient can be fine-tuned This adjustment process is essential for enhancing overall performance.
Almost all drivers have their own purposes The company's servo motors will come with its driver to make their brand
Figure 2 3: Servo amplifier of Mitsubishi
2.2.1.2 Servo uses SSCNET III network
In a Servo system, it is crucial to control the motor's rotation speed to closely match the signal from the controller, while ensuring the rotation dimension aligns with the parameters set by the operator Typically, the motor is configured to rotate in a clockwise direction.
The performance of servo systems relies on the specific driver used to detect pulses, leading to the development of advanced driver series for industrial applications Mitsubishi has launched the J3 and J4 driver series, offering enhanced functionality over previous models The MR-J3 Servo amplifier integrates with the servo system controller via the high-speed SSCNET III network, ensuring uninterrupted real-time data transmission This amplifier is compatible with the MELSERVO-J3 series and various servo motor types, featuring one-touch and real-time automatic adjustments for optimized performance The MR-J3-10B amplifier benefits from improved communication speed and noise resistance, with a maximum connection distance of 50 meters using the SSCNET III network cable.
Torque limits in clamp circuits are implemented on the servo driver to safeguard the power transistors from overcurrent due to speed increases, rapid deceleration, or overload conditions Moreover, the torque limit value can be adjusted to meet specific requirements within the controller.
With this MR-J3 driver line will have the function of communicating with USB, users can use the computer to connect MR-Configuration to install parameters, check
The MELSERVO-J3 series servo motor features a highly accurate absolute position encoder with a resolution of 262,144 pulses per rotation, significantly improving control compared to older driver series By incorporating a battery into the driver servo, an absolute location detection system is established, eliminating the need to return to the home position during resource warnings or interruptions, as the home position is set just once.
Figure 2 4: Configure wire diagram between systems
The MR Configurator2 setup software enables seamless communication with servo amplifiers through a motion controller By simply connecting a personal computer to the motion controller with a cable, users can easily adjust multiple servo amplifiers simultaneously.
The optical fiber cables used for SSCNET III dramatically improve the resistance against noise which enters from the power cable or external device [3]
Figure 2 5: Links between drivers via Cable SSCNET III
A servo motor is a type of specialized motor used to provide a powerful mechanism for certain equipment, lines, or drive mechanisms in the production and manufacturing chain
They play an important role in providing traction that makes the lines or other motors work according
A servo operates through a closed-loop system, where the motor receives signals from the encoder to the driver As the motor rotates, it transmits velocity and position data to the controller via the encoder If any factors impede the desired position, the feedback mechanism alerts the controller Consequently, the controller processes this information and makes necessary adjustments to maintain optimal speed and position according to the initial specifications.
2.2.2.2 Structure of AC servo motor [1]
Similar other two-phase induction motor, the AC Servo comprises of a rotor and a stator
The AC servo motor features a stator with two evenly distributed windings, positioned 90° apart One winding, known as the main or fixed winding, is connected to a constant power source, while the other, the control winding, receives its supply from a Servo amplifier To generate a magnetic field, the voltage applied to the control coil must be 90° out of phase with the alternating voltage of the main winding.
Rotors are designed with a long length and a small diameter, typically made from lightweight aluminum or copper conductors The torsional moment speed characteristics of induction motors exhibit both stable and unstable zones In contrast, AC servo motors are engineered for high stability, eliminating the positive slide area in their twisting moment characteristics As the linear speed increases, the twisting moment in the motor decreases, necessitating a rotor circuit resistor that is both cost-effective and low in inertia Consequently, rotors are usually constructed with a small diameter-to-length ratio, and the air openings between the aluminum rods in shock cage motors are minimized to reduce magnetization current.
2.2.2.3 Working principle of AC servo motor [2]
An AC servo motor operates similarly to a standard two-phase induction motor, generating a rotating magnetic field when two voltages, spaced 90 electrical degrees apart, are applied to its stator phases This rotating magnetic field interacts with the rotor conductors, creating a closed path for currents As a result, the interaction between the magnetic fields and these currents produces torque on the rotor, aligning it with the direction of the field's rotation.
• The speed, position and torque are extremely accurate, less thermos generates and do not fluctuate
• Operational efficiency is higher than 90%, continuous work and less damage
• The control is complex, the parameters need to be installed correctly.
Encoder
A motor encoder is a rotary encoder attached to an electric motor that provides closed-loop feedback by monitoring the motor's speed or position Various configurations of motor encoders exist, including incremental or absolute types, and can be optical or magnetic, as well as available in solid or hollow axis designs The choice of motor encoder depends on factors such as the type of motor, the specific application requiring feedback, and the necessary mounting configuration AC induction motors are commonly utilized in general automation machine control systems due to their cost-effectiveness and durability For applications using AC motors, motor encoders enhance speed control precision, necessitating robust specifications for ingress protection (IP), shock, and vibration resistance.
Figure 2 7: Types of Industrial Encoders
Figure 2 8: Encoder in AC Servo
• One rotating disk with mounting holes rotates around the fixed axis of the motor (Code Disk)
• One located near the turntable is used as a light source (Light Source)
• One photoelectric receiver arranged in a straight line (Photodetector Assembly)
• The circuit board has the function of amplifying the signal (Electronics Board)
An encoder is essential for accurately managing the angular position of rotating discs, such as those found in wheels, motor axes, or any device requiring precise angle determination Encoders are primarily classified into two categories: absolute encoders and incremental encoders.
An Absolute Encoder provides precise location signals, allowing users to avoid manual intervention This device can utilize either Binary or Gray code for its operation.
Absolute Encoder has structure includes light emitter (LED), encoder disk (containing signal-carrying ribbon), a light-sensitive light receiver (photosensor)
Encoder disc is made of transparent material In which, the disc surface is divided into equal angles and concentric circles
❖ Advantages: When the power is lost, the encoder remains the same value
❖ Disadvantages: Manufacturing is complex, the price is quite high, and it is difficult to read the signal
An incremental encoder is an electromechanical device that generates a cyclical signal characterized by an encoder disk featuring an array of pulsed tapes, typically divided into several evenly spaced holes Often made from transparent materials to allow light to pass through, this type of encoder generally contains one or two main holes, along with an additional locating hole for precise positioning.
❖ Advantages: The price is quite cheap because of the simple structure, easy handling of the signal brought back
❖ Disadvantages: Operating for a long time is unstable, easy to errors
Encoders are essential devices widely used in various applications, playing a crucial role in measuring speed, direction, and distance Their ability to provide accurate information allows users to make precise determinations in their respective fields.
Encoders play a crucial role in the mechanical industry by serving as precise measuring devices that determine the exact position of motor axes This technology allows controllers to detect deviations via the control panel, enabling timely adjustments to maintain optimal performance.
Robotics applications rely heavily on encoders, which are essential for enabling robots to automatically adjust their speed and position These systems ensure that robots can navigate to specified locations effectively Additionally, encoders are often designed with compact configurations to seamlessly integrate into various robotic designs.
DC brushless motor overview
Today, brushless motor is no stranger to Vietnamese industry The use of brushless motor to avoid noise from the motor and can save more electricity than other motor
A brushless motor, or Brushless DC Motor (BLDC), is an electric motor that utilizes an electronic circuit to convert DC current into mechanical energy, allowing the rotor to move around the stator As a synchronous motor, the rotor's speed matches the magnetic speed, and the absence of brushes minimizes friction and noise, resulting in smoother operation and energy efficiency Due to these advantages, brushless motors are commonly employed in various industrial applications, including automation, printers, automotive systems, and measurement equipment.
A brushless motor, like other motor types, features coils arranged 120 degrees apart within the stator The rotor body is equipped with a magnet rod, which facilitates magnetic stimulation Unlike traditional permanent magnet motors, brushless motors rely on a controller to detect the rotor's position, enabling operation The primary components of a brushless motor include the stator, rotor, and Hall effect sensor, which work together to ensure efficient performance.
A position sensor, typically a Hall sensor, is essential for detecting the rotor's position in BLDC motors, converting this information into an electrical signal Most BLDC motors incorporate three Hall sensors embedded in the stator to accurately sense the rotor's position.
The stator windings of a BLDC motor are linked to a control circuit, such as an integrated switching or inverter circuit, which energizes the windings in a specific sequence to create a rotating magnetic field This rotating field causes the permanent magnets on the rotor to align with the energized stator electromagnets As alignment occurs, the control circuit activates the next set of electromagnets, allowing the rotor to continue its motion seamlessly.
2.4.4 Advantages and disadvantages of BLDC [6]
Brushless motors have many advantages such as:
• Because there is no coal, there is no regular maintenance
• High-speed range and no noise when operating at high speed
• High-performance and output power ratio due to the use of permanent magnets
• High operating speed when loaded or free due to no brushes
• High life expectancy and no need to check or maintain for commutator system
Due to its compact structure and built from permanent magnets, the price is quite high
Brushless motor has several main applications:
• Load application in transformation: Used in household appliances, air compressors, fans, pumps, etc
• Application location: Application in the industries of robot automation, control in industry, simple belt driven systems.
Programmer Logic Controller
In today's industrial landscape, Programmable Logic Controllers (PLCs) play a crucial role in automation systems, significantly contributing to the advancement of our country's industry The integration of PLC technology not only enhances operational efficiency but also helps us compete with developed nations like Japan and Germany However, the implementation of PLC systems can be costly and necessitates skilled programmers to ensure effective operation.
A Programmable Logic Controller (PLC) is a crucial device used for implementing logical control algorithms It operates by receiving inputs from external devices like sensors and buttons, which influence its execution commands for output actions.
It works by scanning the states of the input signal When there is a change from any input, based on logic, the corresponding output program will change
Programming languages vary by manufacturer, with ladder logic being one of the most popular today Leading PLC manufacturers include Siemens, Mitsubishi, Omron, and Rockwell Customers select different PLC lines based on cost and demand, as each manufacturer offers distinct types of PLCs, each with its own advantages and disadvantages.
2.5.2 Working principle and structure of PLC [4]
When the power supply is supplied to the PLC and it is converted to RUN mode, the processor starts scanning the control program in the program memory
The controller first obtains the status of all the inputs from the input image table and then executes the logic function according to the control programs
The solution is recorded in binary format within the output image table, and this information is subsequently transmitted to the output modules These modules are responsible for converting the binary data into a suitable format for output devices and executing the corresponding functions.
The structure of a PLC includes input module, CPU, output Module, memory, programming device
The input module transforms high power signals, such as 220 V AC or 24 V DC, from devices like push buttons, limit switches, level sensors, and proximity sensors into low power signals suitable for digital circuits within the CPU.
Such an input module converts all input signals into binary format with address It then records all the input data in the input image table in RAM memory
The CPU serves as the brain of the PLC, executing and managing all operations based on the provided program instructions To carry out these instructions, the processor retrieves input data from the input image table, processes it logically, and then records the results in the output image table This entire procedure is known as the scan process.
The output module functions as a signal amplifier, transforming low power signals from the output image table into high power signals that are ideal for driving output devices like contactors, solenoids, relays, and indicator lamps.
System Memory (ROM) is essential for permanently storing the information required by the operating system Application memory is divided into two components: user program memory, which holds the user's program instructions, and variable data memory, which stores dynamic data.
2.5.3 Advantages and disadvantages of PLC
• Easy programming, easy-to-learn programming language
• Perform complex algorithms and can change the program as you want
• The memory capacity is quite large, so it can contain medium and complex programs
• The module structure makes it easy to change or expand I/O
• Compact circuit, easy to repair and maintain
• The resistance is quite good, works well in the industrial environment
• Communicate with other smart devices such as modules, computers, communication network connectivity
• To be able to give an operating system, there is a highly specialized programmer, professionally trained
• High price, but there are still brands that produce products that suit the needs of customers
Position control
The number of pulses per rotation is a crucial setting for achieving desired accuracy in servo motor control This value indicates how many pulses are needed for the servo motor to complete a single revolution, which is determined by the pulses fixed on the encoder disk.
The movement amount per rotation determines the distance that the mechanical mechanism, such as a ball screw or turntable, moves in relation to the motor axis This measurement can be set in millimeters for linear motion, in degrees for rotary systems, or directly in pulses for specialized applications.
Pulse output mode: Set the command pulse signal transmission method and rotation direction to suit the connected servo controller
Table 2 1: Principle of pulse generator control servo motor
Pulse/sign • The number of revolutions as well as the rotation speed depend on the pulse signal
• Reversible rotation signal independent of command pulse to control rotation direction.
• For servo motors, the reverse rotation is not fixed, but it is usually clockwise
Our team can manipulate the servo's rotation direction using two pulse receivers A pulse received by input A triggers clockwise rotation, while a pulse at input B causes the motor to rotate counterclockwise.
• Which input rotates in which direction can be set directly in the parameter or transmitted from the controller to the servo driver
Pulse/pulse • The direction of rotation is controlled by the phase difference between the two pulse outputs
• Turn forward when phase B is 90 degrees behind phase
• Reverse when phase A is 90 degrees higher than phase B
Pulse output mode: set the command pulse signal transmission method and rotation direction to suit the connected servo controller
Output signal logic (Output logic signal): can choose one of two modes positive logic - receive high level command or negative logic - receive low level command
Figure 2 15: Illustrate the direction of rotation of the motor
To ensure proper functionality, the servo motor's rotation direction must be set correctly, as the default is not configured for reverse rotation The right direction is represented as either clockwise or counterclockwise Our team needs to adjust the servo controller so that the motor rotates in the direction corresponding to a positive reported position value, indicating forward rotation, while a negative value signifies reverse rotation.
Figure 2 16: Travel limit for the structure
Virtual mechanical system
According to [10], "Synchronous control" can be achieved using software instead of controlling mechanically with gear, axis, speed change gear or cam, etc
Synchronous control aligns movement with the input axis—be it the servo input axis, command generation axis, or synchronous encoder axis—by configuring the parameters for synchronous control and initiating it on each output axis.
Figure 2 17: Virtual mechanical system overview
The input axes used are of 3 types including real servo axes, virtual servo axes and synchronous encoders
A real servo axis utilizes an input spindle driven by one of the available servo motors in the system, such as a conveyor, ball screw, turntable, or linear actuator, to operate other components The auxiliary mechanisms are designed to move in accordance with the motion of the servo axis, which is configured based on specific parameters established within the system.
A virtual servo axis operates solely within the software environment, controlling the main axis in synchronous mode without being physically external to the real system This virtual motor facilitates the coordinated movement of other motors and structures, ensuring seamless integration and operation throughout the system.
Figure 2 18: Real/ virtual servo axis
Synchronous encoders, which can be either absolute or relative, are essential components in rotating structures of a system, such as frequency-controlled motor heads or turntables These encoders serve as the primary axis for virtual machine systems, effectively driving the other components and structures within the system.
Gears transmit pulses to the output axis by multiplying the input axis pulses with the gear ratio The gear ratio is determined by dividing the number of gears on the input axis by the number of gears on the output axis.
The clutch functions to transmit and disengage command pulses from the main or auxiliary axis input to the output axis module by turning the clutch ON or OFF, effectively controlling the operation and stopping of the servomotor.
A speed change gear module is used to change the input speed from the main axis/ auxiliary axis/ composite auxiliary axis gear during operation
With speed change from a speed change gear module, operation is executed with linear acceleration/deceleration based on the setting for the speed change gear smoothing time constant
The differential gear set operates by subtracting the auxiliary input axis distance value from the main axis magnetic distance value, transmitting the result to the output axis Notably, when the main axis is idle, the auxiliary axis linked to the differential gear takes control, driving the output axis in the opposite direction to the main axis Ultimately, the output axis distance value is calculated as the difference between the main input axis distance value and the auxiliary axis distance value connected to the differential gear.
The cam disc functions to control the movement of a connected machine in alignment with the designated cam disc pattern It completes one full revolution based on the number of pulses generated per rotation of the cam axis.
The following operations can be performed with cam functions
• Two-way operation: Reciprocating operation with a constant cam strokes range
• Feed operation: Cam reference position is updated every cycle
• Linear operation: Linear operation (cam No.0) in the cycle as the stroke ratio is 100%
The output axis is controlled by a value (feed current value), which is converted from the input value (cam axis current value per cycle) by cam data
Figure 2 24: Cam disc types and functions
CC-Link communication standard
According to [9], CC-Link is an abbreviation of Control & Communication Link Its purpose is to integrate system control and communication
CC-Link is an open network Its specification has been disclosed by assembling the products of many participating vendors (partner manufactures)
A CC-Link system consists of the following four devices
When selecting slave stations, it's essential to consider potential discrepancies in device locations and transmission methods, which can vary based on the type of station This ensures that the chosen stations align with our specific objectives.
Type of station Description Location
Manages and controls the data link system Possesses the network control information (network parameter) One station is required per system
Communicates with the master station and other local stations The module is identical with that for master station, but becomes a local station as the setting differ
Carries out cyclic and transient transmissions Local station is also regarded as intelligent device stations
Includes a remote I/O station and a remote device station
Carries out cyclic transmission only No transient transmission is taken place
Table 2 2: Types of station used in CC-Link
A single safety master station can connect up to 64 safety remote I/O stations, standard remote I/O stations, and remote device stations, provided that all specified conditions are met.
2.8.4 Relationship between Remote I/O devices and the Programmable Controller CPU Devices
• Bit information (ON/OFF) is transmitted using remote input devices (RX) and remote output devices (RY)
• It is not possible to directly remote I/O devices (RX/RY) in a sequence program
• Remote I/O and programmable controller CPU devices are updated automatically based on the assignments set in the network parameters This action is called Automatic refresh
Using the automatic refresh function, our team are able to carry out programming as if our team are accessing the modules mounted on the base
Figure 2 26: The relationship between I/O devices and PLC CPU
DESIGN AND MODEL CONSTRUCTION
Introduction to the project
Before embarking on this graduation project, our team extensively researched the synchronous control and flying shear systems currently utilized in the industry As a result, we have successfully designed and constructed a model of the flying shear system for this project.
Design requirement for the model:
For optimal performance, the mechanical components of the machine must be robust and stable during operation This model features two primary axes: the conveyor and the cutter axis It is essential that all mechanical parts are installed correctly and arranged properly to facilitate efficient wiring.
Before wiring, consult the catalog of electrical devices to ensure proper connections Each end of the electrical wire should feature a symbol to simplify the wiring process It's essential to carefully place the wires in the trough and ensure they are securely connected to prevent electrical leakage, thereby safeguarding both the operator and the equipment involved in the model.
Below is a picture of the model:
Figure 3 1: Model of synchronous control in Flying shear system
Model of synchronous control in flying shear system with structured three main components:
• Mechanical component: Including conveyor axis and cutter axis In which conveyor axis using DC brushless motor, otherwise, cutter axis using servo motor
• Electricity component: Including electrical equipment such as: power supply unit, circuit breaker, sensor, driver, etc
• Control component: Personal computer and a control screen on GT SoftGOT2000 software.
Mechanical component
Figure 3 2: Mechanical part of conveyor axis and cutter axis
The flying shear system model features two main axes: the conveyor axis and the cutter axis An encoder is integrated into the conveyor axis to accurately measure the sample distance This model employs a ball screw to transform rotational motion into linear movement, and it includes two proximity sensors on the ball screw to restrict its travel effectively.
• The conveyor axis is driven by a DC brushless motor 60W
• The cutter axis is driven by AC servo motor HG-KR13 100W with an internal ball screw axis with steps of lead is 10mm
3.2.2 Steps for the construction of mechanical component
The model completed in the following steps:
Step 1: Install the conveyor onto the 10mm thick aluminum table After completing the conveyor mounting, our team continues to mount the cutter axis, and this cutter axis will mount parallel to the conveyor axis
Step 2: Mount three proximity sensors on the cutting axis to limit the stroke of ball screw to avoid damaging the servo motor On the conveyor axis, an encoder is also mounted to measure the length of the sample when the flying shear system is running in cut-to-length mode, besides, a laser sensor is also mounted at the top of the conveyor to detect the object pattern when the flying shear system runs in marker cutting mode
Step 3: After completing step 1 and step 2, a brushless DC motor will be mounted on the plate and connected to the conveyor through a coupling The ball screw mounted on the cutter axis is driven by a 100W servo motor and is connected through a coupling Step 4: Drill holes to attach the rods that place the devices and wire troughs.
CONTROL PROCESS
Control requirement
There 2 requirements for running cutter axis:
In length mode, we assess the accuracy of the length cutting mechanism using conveyors equipped with six black points, each spaced approximately 261mm apart To ensure precise alignment between the cutter axis and the conveyor axis, our group has configured the cutting lengths to 261mm and 522mm.
Figure 4 1: Distance between 2 black points
For marker cutting, my team marked 2 black points, this black point is detected by the laser sensor with the highest response time of 80ms
Figure 4 2: Black point marked and laser sensor
System operation
Figure 4 3: Flowchart of the operating flying shear system
The flowchart illustrates the operation of the flying shear system, outlining essential steps such as setting the home position for both axes, selecting the operational mode, activating synchronous mode, and adjusting the speed for each axis.
To ensure proper synchronization and operation, first calculate the parameters for axis 1 Next, execute the operations for axis 2 while synchronizing axis 1 to axis 2 To safely halt all axes, begin by stopping axis 2, followed by turning off the synchronized axis 1 Initially, both axes should be configured correctly for optimal performance.
To begin the process, establish the correct distance for the initial position Next, choose the marker or length cutting mode Activate the Synchronous mode and set the speed for the conveyor (axis 2) The CPU will then calculate the necessary parameters to configure synchronous axis 1 Following this, synchronous axis 1 (the cutter axis) will operate in coordination with axis 2 (the conveyor axis) To halt axis 1, you can either stop axis 2 or disable the synchronous function for axis 1.
Establish the motion equation of the 2 axes
The 2 synchronous axes operate with distinct movement modes: the 1st axis gear achieves a smooth, linear motion, while the 2nd axis gear engages in a consistent, rapid movement.
To be able to better understand, our team will distinguish these 2 forms of movement
Uniform rectilinear motion refers to movement along a straight path where the average speed remains constant throughout Key formulas associated with this type of motion are essential for understanding its principles.
• Equation of motion x=x 0 +vt with x0 is the coordinates at the time, t 0 , x is the coordinates, v is the average velocity
In uniformly accelerated straight motion, the trajectory follows a straight line, with velocity increasing steadily over time The acceleration remains constant, maintaining the same direction throughout the motion, and both the acceleration and velocity vectors point in the same direction Key formulas related to this motion are essential for understanding its dynamics.
• Formula for the relationship between acceleration and velocity: v 2 − v 0 2 = 2 as
In our team’s conventional setup, we designate the cutting axis as axis 1 and the conveyor as axis 2 Upon powering on the system, both axes are set to their Home positions, indicating a position of 0 However, the actual positions of the two axes differ, leading to a misalignment To achieve proper synchronization, it is essential that the positions of both axes coincide after a specified duration, ensuring they meet after a certain time interval.
Axis 2 must travel a distance of s (mm) before signaling the start of motion for axis 1 During its movement, axis 2 maintains a constant speed, exhibiting uniform rectilinear motion Axis 1 initiates its movement upon receiving a synchronous signal from the controller, accelerating uniformly until its speed matches that of axis 2 over a period of t1 (s) The synchronization of both axes occurs once their positions align.
2 axes coincide and the speeds are equal After finishing the synchronization, axis 1 will return to the original position to prepare for the next process
Establish the motion equation of axis 1 and axis 2:
Figure 4 6: Velocity versus time graph of axis 1 and axis 2
2𝑎𝑡 2 When distance axis 2 meet axis 1 equal: 𝑥 1 = 𝑥 2
2𝑠 When 2 axes meet thus turn the synchronous mode on:
The function (3) has one solution:
Figure 4 7: Graph showing speed of 2 axes versus time
EXPERIMENT RESULTS
Cut-to-length
✓ Testing length mode at speed 174 mm/s and cut length 522mm
Figure 5 1: Real feed current value at conveyor speed 174 mm/s
Figure 5 2: Calculated value of waiting range - cut length 522mm
From figure 5.1, real distance between axis 1 and axis 2 is:
147.24 - 145.5 = 1.74 mm which equal to waiting range 522 - 518.52 - 1.74 = 1.74mm
✓ Testing length mode at speed 522 mm/s and cut length 522mm
Figure 5 3: Real feed current value at conveyor speed 522 mm/s
Figure 5 4: Calculated value of waiting range - cut length 522mm
From figure 5.3, real distance between axis 1 and axis 2 is:
135.32 – 127.49 = 7.83 mm which equal to waiting range 522 – 506.34 – 7.83 = 7.83mm
✓ Testing length mode at speed 261 mm/s and cut length 522mm
Figure 5 5: Real feed current value at conveyor speed 261 mm/s
Figure 5 6: Calculated value of waiting range - cut length 522mm
From figure 5.5 real distance between axis 1 and axis 2 is: 57.15 – 53.24 = 3.91mm which equal to waiting range.
CONCLUSION AND THESIS DEVELOPMENT
Conclusion
❖ After completing this project, our team met the requirements:
✓ The system accurately runs in length mode
✓ The system accurately runs in marker mode
✓ Run exactly in real range of cutting length according to the calculated parameters
✓ The system runs accurately at a wide range of speeds from 43.5 mm/s to 522 mm/s
• System can operate with wide range variable speed from 10 RPM to 120 RPM
• Reduce time for production due to nonstop cutting operation
• Due to reduce time thus it can reduce price of the product
• Using specified protocol such as SSCNETIII, CC-Link thus reduce noise for signal transmission
• Using BLDC motor and increment encoder thus reduce the price of the system
• Since system using ball screw actuator when using these mechanical for long time can cause mechanical wear
• Mechanical system is not complete precise which cause a drift position between conveyor axis and running cutter axis while running synchronous
• Due to distance between laser sensor and running cutter axis is completely equal to 150 mm as measured thus cause tolerance
➢ Build a real Flying Shear System model that can create products
➢ Developed program to run 2 markers continuously while in running synchronous stage
➢ Improved accuracy of mechanical structures as well as newer servo motors to improve system performance and accuracy
[1] Electronicscoach “AC Servo motor.” Electronicscoach.com https://electronicscoach.com/ac-servomotor.html
[2] Electrical Workbook “AC Servo motor- Working Principle, Circuit Diagram, Construction, Characteristics & Applications.” Electricalworkbook.com(Accessed Jun
25, 2021) https://electricalworkbook.com/ac-servo-motor/
[3] ITSUBISHIELECTRIC “MR-J3-_B SERVO AMPLIFIER INSTRUCTION MANUAL.” Mitsubishielectric.com
[4] Tech electronic group “Working Principle of Programmable Logic Controller and Best Features.” Techelectronicgroup.com
[5] Heidenhain “Different Types of Encoders and Their Applications.” Heidenhain.us https://www.heidenhain.us/resources-and-news/types-of-encoders-and-applications/ (Accessed June 1, 2021)
[6] Robu “Brushless DC Motor Working Principle and Applications.” Robu.in
[7] Dynapar “Motor Encoder Overview.” Dynapar.com https://www.dynapar.com/technology/encoder_basics/motor_encoders/
[8]Emerson Industrial Automation, “User guide – Flying shear – Application software”
[9] CC-Link training course of Mitsubishi
[10] MELSEC-Q/L QD77MS/QD77GF/LD77MS/LD77MH Simple Motion Module User’s Manual (Synchronous Control)
[13] BLE Series CC-Link Operating Manual
[14] BLE Series Installation/ Connection Operating Manual