Coconut is the main tropical economic crop in China and is mainly produced in the tropical coastal areas of South China. Coconut is extremely versatile, rich in protein and multivitamins, and has high nutritional value and value. Coconut can be processed into coconut oil, copra, coconut bran, dehydrated coconut and coconut activated carbon. In Hainan, for example, it is mainly based on traditional processed products such as coconut milk, coconut milk, coconut sugar and coconut flakes. Other coconut products such as coconut oil, coconut fiber and coconut shell activated carbon that are needed in the domestic market need to be imported from abroad. Most of the coconut processed products need to be cut before they can improve the processing and production, so it is of great economic value to improve the efficiency of coconut cutting. To this end, this paper introduces a method of coconut cutting, based on PLC design and research on the control of coconut cutting process, and the control program of the cutting process and the corresponding ladder diagram.
1 coconut cutting machine 1.1 cutting machine mechanical structure cutting machine mechanical structure as shown. It adopts a secondary transmission device, and the stepping motor cooperates with an asynchronous motor to realize the cutting motion. Due to the large volume of the cut coconut, an indexing plate indexing device is used for improving work efficiency. The cutting machine is designed as a vertical cutting structure, and the mechanical part is mainly composed of a whole body, a power device, a transmission device, a feeding mechanism, a clamping mechanism and a cooling system.
Overall kinematic principle 1.2 cutting machine cutting machine movement mechanism is divided into two parts: -05-26 Fund: Hainan Natural Science Foundation of China (808127) Corresponding author: Zhang Yan (1978-), female, Hubei Ezhou lecturers , Master, (E-mail) z cutting exercise. The main motor drives the belt transmission mechanism to rotate the blade. At the same time, under the action of the counterweight balance force, the stepping motor drives the worm gear to move, thereby driving the worm movement; the worm wheel drives the rocker arm to swing up and down to realize the cutting motion of the cutter.
Indexing exercise. In order to achieve automated production and improve efficiency, a single-step 90-rotation automatic indexing device is used to control the movement of the stepping motor by receiving signals from the sensor, thereby achieving the indexing action.
The indexing action of the table must be rhythmically matched with the cutting motion of the tool to drive the workpiece to be correctly indexed, so as to prevent the tool from interfering with the movement of the table and damaging the device. When the cutting motion starts, it should be ensured that the indexing device has completed the rotary indexing action, the material stops, and waits for cutting.
After the cutting movement is completed, the tool returns and the indexing action can be continued when the tool is completely detached from the material.
1.3 Sensor selection and working principle The sensor uses photoelectric proximity switch. The photoelectric switch is mounted on the indexing plate, protrudes to the groove of the rotary table, close to the workpiece to be processed, and installs the induction metal strip at the appropriate position on the tool. When the tool is cutting motion downward and the metal strip is close to the photoelectric sensor, the control system receives the signal and completes the corresponding action; when the tool moves upward and the metal strip leaves the sensor, the control system receives the opposite signal and controls the motion state of the corresponding device. .
2 control system hardware structure 2.1 control system overview The cutting machine system's executive components are mainly composed of main asynchronous motor and stepper motor. The asynchronous motor adopts frequency converter for frequency conversion speed regulation, and the stepping motor adopts a special driver for subdivision driving. The core controller of the control system needs to provide appropriate control signals, and the asynchronous motor and the stepping motor coordinate motion to complete the cutting action. 3. PLC Control system With the rapid development of electronic technology and information technology, a variety of practical control technologies have emerged, such as relay control technology, computer control technology, single-chip control technology and PLC control technology. 4. Programmable Program Controller (PLC for short) It is an electronic device for digital operation operation designed for industrial applications. It is a controller with memory and programmable program. It can store and execute instructions, perform operations such as logic operations, sequence control, timing, counting, and arithmetic operations, and control various types of machinery and production processes through digital and analog input and output. PLC has the advantages of complete functions, flexible combination, convenient programming, high reliability, short development cycle, etc., so it is widely used in various fields of industrial production and control.
The cutting machine adopts PLC as the core controller to realize the automatic control of the entire structure.
PLC hardware system design PLC hardware system is generally composed of central processing unit (CPU), storage unit, input and output interface, power supply, I / O interface, external device interface, programming equipment, etc. 0. Various signals of external devices as The variables are input to the PLC through the interface, and after logical operation and data processing, they are sent to the output interface in the form of variables, so that the output device can control various movements of the external device. The hardware system structure is as shown.
3 software structure of the control system 3.1 design of the main control program of the system The main control program gives the structural flow of the entire motion process, connecting each module. First, initialize the initial value of each software, memory, I/O devices, and hardware devices, and then run the main control unit to implement the control functions of the device. In order to improve the variety of process performance of the cutting machine, two modes of operation, manual control and automatic control, are designed, and the automatic control mode adopts the direct cutting mode. For the system main control program flow chart.
3.2 System Manual Control Program Design After the system is powered on, the reset action is first performed, and then the operator selects the control mode.
To enter the manual control, you need to press the manual operation button to work in the system and enter the manual control mode. Manual operation enables individual control of the movement of the table, the up and down feed of the rocker and the rotation of the tool. Manual control is realized by means of multiple buttons and PLC pass-through. Each button is assigned to the appropriate PLC internal address, and the button and PLC cooperate to control the controlled motor.
Manual operation, press the manual control button, enter the manual control state, the corresponding address of the manual control button is X3. 3.3 System test program design test program is used to determine the tool Z direction and the tool cutting movement fast forward and work forward Turning point. The working process is to start moving downward to the working fast-forward turning point when Z is reset to the highest point, then move down to the lowest point, and then start moving upwards. The counter records the number of times of the entire stroke in the Z direction, and then the indexing device receives After the signal is running. Test the program flow chart for the system.
3.4 System main control program ladder diagram According to the characteristics and requirements of the control system, the Japanese Mitsubishi programmable controller type is selected as the main controller.
The number of input and output points of the controller is 8, and the available points of the expansion module are 24~320, as shown in Table 1.
According to the process of the cutting machine and its control requirements, the I/O points are allocated as shown in Table 1.
System master program ladder diagram. The master program ladder diagram is shown as shown. The corresponding mnemonic code is shown in Table 2.
Table 1 I/O points allocation Tab. Input and output test system counter counting indexing program start Z-direction fast-forward photoelectric test parameter Z to work in manual execution Z-direction reset manual feed table 2 main control program mnemonic instruction table 4 conclusion With the rapid development of the economy, domestic and foreign markets are increasingly demanding coconuts and processed products. Coconut is one of the major tropical economic crops in China, and the development of its processing industry can promote the economic development of the corresponding regions. This paper first introduces the method of cutting coconut, and designs the control system of coconut cutting process based on PLC. The structure of the control system is introduced from two aspects of hardware and software. The software program includes the flow chart of the control program of the main program and test program and the corresponding The ladder diagram has great value for improving the efficiency of the cutting process before the deep processing of coconut. It can improve the economic benefits of coconut processing and increase the degree of automation, which is conducive to the development of the coconut processing industry.
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