A design scheme for the control system of a lithium battery automatic glue sticking machine

　　As the country's support for the new energy vehicle industry increases year by year, its core energy field - power lithium batteries will enter a period of rapid development. Compared with traditional energy batteries, lithium batteries have the characteristics of high energy density, light weight, long service life, green environmental protection, and high reuse rate. At present, there are two main manufacturing processes for manufacturing lithium batteries, one is winding and the other is lamination. The lamination process is often used to manufacture large-capacity new energy lithium batteries. The last process of the core component of the laminated lithium battery - the battery cell is gluing. As customers have higher and higher requirements for the process level, efficiency and quality of products, traditional manual gluing can no longer meet the requirements of modern production, so the research of efficient and automatic gluing machines is an urgent requirement of the market. This article focuses on a PLC-based lithium battery automatic gluing machine control system, and elaborates on the hardware and software design of the system in detail.

　　2. Working principle of lithium battery automatic glue sticking machine

　　The lithium battery automatic glue sticking machine is a fully automatic packaging equipment with automatic material picking, glue sticking, short circuit detection and material unloading functions.

　　Its working principle is to automatically prepare the tape while the automatic stacking machine produces lithium battery cells. The specific steps involved in this process are five processes: glue pressing, glue sandwiching, glue pulling, glue cutting and vacuum adsorption. After the stacking machine produces lithium battery cells, the cell taking robot takes out the cells on the stacking table and transfers them to the glue sticking machine through the screw rod for glue sticking. Since the battery produced by the stacking process is relatively large, sticking one tape often cannot achieve the purpose of fastening the battery cell, so a three-step glue sticking process is designed here. After each glue sticking, the battery cell moves a distance (the distance can be set through the touch screen), and the automatic glue sticking machine prepares the tape. After the tape preparation work is completed and the cell taking robot stops, the glue sticking process is carried out, and this is repeated three times. Each time the glue is applied, the photoelectric color sensor is used to detect whether the tape is applied. If the tape is applied normally, the next process is carried out. If the tape is not applied normally, the previous glue sticking position is returned to re-apply the glue. After the tape pasting process is completed, the battery cell robot transports the taped battery cell to the short-circuit test position, and uses a short-circuit tester to perform a short-circuit test. If it passes, it is transported to the unloading conveyor belt for unloading. If it fails, it is transported to the waste box for unloading.

　　3. Hardware design of electrical system

　　3.1 PLC selection

　　In the design of the electronic control part of the automatic glue sticking machine, considering that the glue sticking machine has many processes and complex operation, and PLC has the advantages of high reliability, strong control function, convenient programming, and easy operation, the author of this article uses a programmable logic controller as its core control component. The control system uses the SYSMAC CP1H-XA40DT-D model PLC produced by Omron Corporation of Japan. The CPU unit of the PLC uses a DC24V power supply, DC24V input, transistor drain output, built-in input 24 points, output 16 points, and can realize high-speed counter 4 axes and pulse output 4 axes. The basic instruction is 0.1 microsecond per step, the maximum program capacity is 20K steps, and there are about 400 types of instructions. It is a powerful small integrated PLC. Due to its compact structure, powerful functions and high cost performance, it is very suitable for the design requirements of this system.

　　3.2 Hardware Configuration

　　The hardware configuration block diagram of the system is shown in Figure 1, which includes the CPU unit, input (photoelectric position switch and glue detection sensor), operation panel (touch screen and indicator light), control components (servo drive and solenoid valve), actuators (servo motor, DC motor, cylinder), etc. The motor for taking out the battery core is set with left limit, right limit and origin; the glue pulling cylinder, glue cutting cylinder and glue sticking cylinder each have two photoelectric position switches to detect whether the cylinder is in place; the glue sticking detection sensor detects whether the glue tape is stuck on the battery core each time. The touch screen serves as the operation interface of the equipment control, accepts the operation instructions from the operator and indicates the operation status of the equipment. The PLC and the touch screen communicate through the RS232 communication cable. The motor for taking out the battery core adopts a servo motor, which is controlled by a servo drive; the unloading motor adopts a DC motor; the solenoid valve adopts a two-position five-way solenoid valve to control the advance and retreat of the cylinder.

　　3.3 Allocation of input and output points

　　The production process of the automatic glue sticking machine consists of several parts, including material taking, glue sticking, short circuit detection, and material unloading. The PLC input signals of the automatic glue sticking machine include: start, stop (stop after completing a cycle), emergency stop, front limit of the battery cell motor, origin of the battery cell motor, rear limit of the battery cell motor, alarm of the battery cell motor, good or bad glue sticking detection, short circuit detection, glue pulling cylinder limit, glue pulling cylinder return limit, glue cutting cylinder limit, glue cutting cylinder return limit, glue sticking cylinder limit, glue sticking cylinder return limit. The output signals include: forward rotation of the battery cell motor, reverse rotation of the battery cell motor, forward rotation of the material unloading motor, reverse rotation of the material unloading motor, solenoid valve of the battery cell cylinder, solenoid valve of the adhesive tape cylinder, solenoid valve of the adhesive tape cylinder, solenoid valve of the adhesive tape cylinder, solenoid valve of the adhesive tape cylinder, vacuum solenoid valve of the adhesive tape cylinder, vacuum solenoid valve of the adhesive tape cylinder, and solenoid valve of the short circuit detection cylinder.

　　4. Software design of control system

　　The program of the automatic glue sticking machine control system consists of two parts: one is the touch screen program, and the other is the PLC program.

　　4.1 Touch screen program

　　The touch screen program completes the dialogue between the operator and the PLC, and is mainly composed of three parts: automatic operation, parameter setting, and manual operation. The automatic operation is mainly composed of three buttons: start, stop, and emergency stop, which are used to control the start, stop (stop after a cycle), and stop after an emergency of the machine; the parameter setting is mainly used to input the position of the first, second, and third tapes relative to the origin of the battery core motor; the manual operation is mainly composed of two parts: the cylinder manual button is used to manually control the advance and retreat of each cylinder in the system, and the motor manual button is used to manually control the forward and reverse rotation of the motor. The touch screen of this control system adopts Eview MT510 produced by Buke Company.

　　4.2 PLC Program

　　The main program flow chart of the automatic glue sticking machine is shown in Figure 2. First, the initialization operation is performed, the material picking motor returns to the origin, and all cylinders return to the initial state. Then it is determined whether the battery cell is stacked. If it is not stacked, it continues to wait. If it is stacked, the battery cell robot takes the battery cell to the first glue sticking position for glue sticking. After the glue sticking is completed (the glue sticking cylinder returns to the initial limit), the material picking robot takes the battery cell to the second glue sticking position for glue sticking, and so on until the third glue sticking position is completed. In this process, after each tape is applied, the color sensor detects whether the glue is applied. If no tape is detected, it is re-applied. After the three tapes are applied, the short circuit detection of the battery cell is performed. If the positive and negative poles of the battery cell are short-circuited, the battery cell is placed in the waste box. If the positive and negative poles are well insulated, the battery cell is placed on the conveyor belt, and the conveyor belt motor is started to transfer the battery cell to the next process. So far, one cycle is completed, and the next cycle begins until the stop button is pressed.

　　5. Conclusion

　　The automatic glue sticking machine designed in this scheme is designed based on the customer's feedback that the battery cells produced by the stacking machine are difficult to unload, the efficiency of manual glue sticking is low, and there is no short circuit detection function. It is mainly used to update and transform the previous stacking machine. According to the customer's feedback, it has met the customer's requirements and expected design effects, the efficiency has been greatly improved, and the manpower has been reduced, the automation level has been improved, and the lithium battery cell processing procedures have been fully automated, thus proving the practicality of this scheme.