Basic Introduction
Timber is produced by processing logs into planks of a certain length, width, and thickness using a debarker, rotary cutter, and panel cutter. These planks serve as raw materials for the production of plywood, decorative panels, and other wood products. The wood used for decoration in our daily lives is made from these cut planks.
The veneer cutting machine is a pre-processing step in the panel cutting machine. Currently, its production efficiency is relatively high. Before the application of automatic panel cutting machines, most panel cutting machines were semi-automatic, which involved manually measuring the cutting distance by leaning against a board and using a foot switch to control the cutting blade. This resulted in low cutting accuracy and low efficiency. Typically, one veneer cutting machine required three panel cutting machines to ensure continuous production, and it consumed a lot of manpower. As enterprises need to improve production efficiency and control accuracy and reduce labor costs, the demand for automatic panel cutting machines is becoming increasingly urgent.
This case study mainly introduces how to achieve automated control of CNC panel cutting machine equipment using Guangzhou Bowei Servo Technology's BWS servo system products.
Equipment Introduction
1. Rack
The frame is made of angle steel and is equipped with anchor bolts for fixing, which reduces the impact of equipment vibration.
2. Transmission mechanism
The power transmission system of the equipment includes a 4kW conveyor servo motor, a 2.2kW cutting servo motor, and related reducers and gear sprocket mechanisms. The conveyor motor is driven by a BWS-BB-004G33B servo controller, which drives the feeding and discharging mechanisms through a 1:19 sprocket reducer to complete the feeding and discharging actions. The cutting servo motor is driven by a BWS-BB-2R2R33B shearing servo controller, which transmits power to the cutting axis through a 1:17 reducer to complete the cutting action.
3. Feeding mechanism
Composed of belt rollers and conveyor belts, it transports the wood boards shaped by the veneer to the cutting mechanism. It is required to use flat belts to ensure smooth conveying and avoid the jumping of the material to be cut, which would affect the encoder's length measurement.
4. Cutting mechanism
The cutting mechanism is the key component of the entire equipment. It consists of an upper blade roller and a lower rubber roller. The blade roller is approximately 2 meters long and 280 millimeters in diameter, and can be configured with either a single blade or a double blade. It can cut wooden boards with a maximum width of 1.8 meters. The cutting action is completed when the blade roller and the rubber roller rotate relative to each other. Generally, the blade roller has a large moment of inertia, which can cause impact on the machine tool during cutting, resulting in a high power requirement for the drive unit, especially for direct-drive motors. Therefore, a low-power motor with a speed reducer is used here to reduce the cost of the equipment.
5. Discharge mechanism
The unloading mechanism also consists of belt rollers and a conveyor belt, about 4 meters long, which delivers the cut wooden boards and stacks them.
6. Photoelectric detection system
The equipment has three photoelectric switches for detecting wooden boards and one photoelectric switch for the origin point. It is mainly used to detect whether there is material to be cut and whether the material to be cut has defects, as well as to detect the origin point position of the cutter.
7. Length encoder mechanism
The equipment is equipped with two encoders. One encoder is installed in the feeding section, serving as a length meter for the material to be cut and also as a feedback signal for the main shaft position of the cutter. The cutter shaft performs the cutting action based on the pulse signal fed back by the length meter encoder, ensuring the accuracy of the cutting length. It can be seen that the accuracy of this encoder is related to the overall accuracy of the equipment. A higher resolution encoder can be selected. At the same time, the mechanical installation must be stable and reliable. Generally, a heavy or tensioned metal roller is used to press on the wooden board to be cut, ensuring contact and friction and no relative movement between them. The encoder shaft is installed on the metal roller and does not directly contact the material to be cut. The other encoder is installed on the cutter roller motor shaft, serving as a self-closed-loop feedback signal for the cutter.
8. Electrical control system
The electrical control adopts Delta's overall solution, which is mainly composed of Delta electromechanical products, including servo controllers, text displays, encoders, etc. Among them, the main controller BWS-BB-2R2R33B wheel-switching servo controller is the control core, which completes the equipment control function.
Equipment diagram
Application planning and effects
Based on a comprehensive analysis of the process requirements, the CNC panel cutting machine meets the following requirements:
1. The pre-set cutting length can be adjusted at any time during equipment operation, including switching between three lengths: quick cut length, set length, and tail plate length, in order to save raw materials.
2. Meets the requirement of ±1mm accuracy control.
3. When cutting, ensure that the linear speed of the cutter is the same as the linear speed of the wood board feeding to avoid the baffle or pull caused by the speed difference. This will result in a cleaner cut and less impact.
4. Defects in the wooden boards are detected by photoelectric sensors and treated accordingly.
5. The cutting motion needs to be smooth in terms of acceleration and deceleration, and the overclocking of the servo controller and servo motor, as well as the impact on the mechanical structure of the equipment, should be minimized.
6. Based on the analysis of the equipment control requirements, this is a typical application of flying shear cutting function. The BWS-BB-2R2R33B rotary cutting servo controller has a built-in flying shear function. A BWS overall solution, with the BWS-BB-2R2R33B rotary cutting servo controller as the control core, can be used to complete the cutter control and meet the equipment control requirements.
