In woodworking machinery, such as woodworking band saw machines, the feed department is often controlled by a single chip microcomputer to perform automatic operations. Because the anti-jamming capability of the SCM control system is poor, misoperations and erroneous data are easily generated, causing the operator to make mistakes and thus misuse. And Yitian PLC has good anti-interference and versatility, which makes the control more simple.
1. How does a woodworking band saw work?
The woodworking machines used for sawing logs or wood are classified into woodworking band saws, woodworking circular saws and woodworking frame saws. The so-called woodworking band saw machine is an endless band saw blade that is tensioned on two saw wheels. The ring band saw blade is driven by the electric motor through a saw wheel to perform a continuous cutting motion. The feed of wood can be manual or it can be automatically fed by a sports car or roller. According to the use classification, the band saw machine can be divided into a sports car band saw machine for sawing logs and a re-saw band saw machine for splitting the plate or the square bar.
The band saw machine is a sports car band saw machine. The so-called sports car refers to a feeding car that holds the log to feed the band saw blade. The actions that the PLC needs to complete are positioning controls on the sports car. The power equipment of the sports car is the electrical idea assembled on the chassis. Through the gear transmission, the main shaft of the sports car is driven to reciprocate. The sports car advances to the work schedule, and the sports car retreats and retreats to return. The working process is that, first, the sports car bench runs a certain interval at a certain speed. When the system receives the forward command again, it runs the same interval at the same speed, and this interval can be modified. When the system receives the retreat retreat command, a return trip is performed until this command is cancelled. The forward and reverse rotation of the electric idea control the advancement and retreat of the sports car table. Through the PLC control system to achieve the direction of the control of the electrical idea.
2, PLC selection and I/O point allocation
In order to ensure the control accuracy of the system, the control system of the sports car band saw machine adopts closed-loop control. The actual interval of the sports car bench is calculated based on the pulse signal returned from the rotary encoder feedback. When the sports car table reaches the set interval, the PLC outputs a brake signal to stop the running of the sports car and realize the positioning of the sports car. The PLC control system needs to configure one high-speed pulse signal input. The sports car bench also needs a fixed position for the calculation of the footage and the ruler. The proximity switch installed on the sports car stand can be used to determine the fixed point position of the sports car. Therefore, the system also needs to configure a proximity switch input point. Finally, the system also needs to configure buttons for starting, stopping, entering, leaving, and jogging. Therefore, the system has 8 switch input points. The system's switch output points include only two points, the brake contactor and the retreat relay, which control the direction of the sports car's rest and sports car movement.
To sum up, according to the input and output requirements, taking into account that this system requires a certain number of spare I / O points, ETMX-MSDH32DC-T these configurations can fully meet the requirements of the system.
3, PLC control system software design ![]()
4 Conclusion
The woodworking band saw with Yitian PLC as the control core realized closed-loop position control. Using the PLC's high-speed counting function, the positioning control of the running table of the sports car is realized. Yitian PLC control system has strong anti-interference ability, which improves the machining precision and operability of woodworking band saws.