Due to the fact that the wire cutting machine adopts a high-speed reciprocating feeding method with wire electrodes, the loss of wire electrodes is evenly distributed on nearly 300 meters of electrode wires. Although the loss of electrode wires is extremely small, there are many factors that affect the surface quality of the processed workpiece during the operation of the wire cutting machine. It is even more necessary to reasonably select and match the relevant processing parameters to ensure the surface quality of the processed workpiece.
1, Control and improvement of human factors affecting the surface quality of workpieces in wire cutting
The control and improvement of human factors mainly include the determination of processing technology and the selection of processing methods, which can be achieved through the following points:
(1) Reasonably arrange the cutting route. The guiding principle of this measure is to avoid damaging the original internal stress balance of the workpiece material as much as possible, and to prevent deformation of the workpiece material during the cutting process due to unreasonable cutting route arrangement under the action of fixtures, etc., resulting in a decrease in the quality of the cutting surface. For example, the separation between the workpiece and its clamping part should be arranged at the back to ensure better rigidity during processing. As shown in the figure below, where a is the incorrect cutting route and b is the correct cutting route.
(2) Choose cutting parameters correctly. For different rough and fine machining, the wire speed and wire tension should be adjusted appropriately based on the parameter table. In order to ensure higher accuracy and surface quality of the processed workpiece, the wire tension of the wire cutting machine can be adjusted appropriately. Although the manufacturer of the wire cutting machine provides relevant parameters suitable for different cutting conditions, due to the material of the workpiece, the required processing accuracy, and other factors, people cannot completely copy the cutting conditions introduced in books. Instead, these conditions should be used as the basis and corresponding adjustments should be made according to actual needs. For example, if a workpiece with a thickness of 27mm needs to be processed, an equivalent situation cannot be found in the processing condition table. In this case, adjustments must be made based on the cutting conditions with a thickness between 20mm and 30mm. The main method is to select the standard thickness that should be set for the workpiece thickness that is close to it.
(3) Adopting close range machining. In order to achieve high precision and surface quality of the workpiece, the height of the wire frame is adjusted in a timely manner according to the thickness of the workpiece, so that the distance between the upper nozzle and the workpiece is as close as possible. This can avoid the excessive amplitude of the wire electrode caused by the distance between the upper nozzle and the workpiece, which affects the surface quality of the processed workpiece.
(4) Pay attention to the fixation of the processed workpiece. When the workpiece is about to be cut, its connection strength with the parent material will inevitably decrease. At this time, it is necessary to prevent the workpiece from being skewed due to the impact of the machining fluid. Once skewed, it will change the cutting gap, which may affect the surface quality of the workpiece. In severe cases, it may cause the workpiece to be cut and scrapped. Therefore, it is necessary to find a way to fix the workpiece in the wire cutting machine.
