2021/07/06
Not everything can be done with wire cutting
Analyze and review the processing pattern. According to the existing processing equipment, considering the feasibility of this process method, processing cannot be achieved in the following situations: a workpiece with a narrow slit smaller than the diameter of the electrode wire plus the discharge gap. The internal angle of the pattern is not allowed to have an R angle or the required R angle of the internal angle is smaller than the diameter of the electrode wire. Workpieces of non-conductive materials. Workpieces whose thickness exceeds the span of the wire frame. The processing length exceeds the effective stroke length of the X and Y carriage of the machine tool, and the workpiece requires high precision. Under the condition of meeting the wire cutting process, according to the processing requirements of the parts, such as surface quality and dimensional accuracy requirements, it is necessary to decide whether to choose medium wire wire cutting or slow wire wire cutting for processing. For parts with high dimensional accuracy and good surface roughness, slow-moving wire-cutting machine tools should be used to complete. For these preparations, the silk is too dirty, so let's slow it down!
1) Reasonable selection of workpiece material In order to reduce the deformation of the workpiece caused by wire cutting, materials with good forging performance, good permeability, and small heat treatment deformation should be selected. The material of the work piece shall be subjected to standard heat treatment according to the technical requirements.
2) For the processing of closed holes and some punches for threading holes, threading holes need to be processed before on-line cutting. The position of the threading hole should be consistent with the machining starting point specified during programming.
3) In the selection of wire electrode types, wire wire cutting generally uses molybdenum wire with a diameter of 0.18 mm as the wire electrode; the wire electrode wire for slow wire cutting generally uses brass wire, in addition to galvanized wire, etc. The diameter can be selected according to the requirements of machining accuracy. Try to choose electrode wires with a diameter not less than 0.2mm to obtain a higher cutting speed and reduce the risk of wire interruption during processing.
4) Clamping and correction of the workpiece. According to the processing shape and size of the workpiece, a suitable clamping method is selected to determine the position of the workpiece to be clamped. If the clamping methods of plate parts, rotating parts, and block parts are different, you can choose to use special fixtures or self-designed fixtures to clamp the workpiece. After the workpiece is clamped, it should be corrected. Generally, it is to check the perpendicularity and flatness of the workpiece clamping, and correct the axial parallelism of the reference plane of the workpiece and the machine tool.
5) Threading and adjusting the wire correctly wind the wire electrode on each part of the wire running mechanism to maintain a certain tension on the wire electrode. Use appropriate methods to correct the verticality of the electrode wire, such as wire alignment with a aligner, wire alignment with sparks, etc.
6) Positioning of the electrode wire Before wire cutting, the electrode wire should be accurately positioned to the starting coordinate position of the cutting. The adjustment methods include visual inspection, spark method, and automatic alignment. The current CNC wire-cutting machine tools all have the function of contact sensing, and they all have the functions of automatic edge finding and automatic center finding. The alignment accuracy is high, and it is very convenient for electrode wire positioning. The operation method varies from machine tool to machine tool. Use high-tech software to generate code, which is programming, WEDM programming is the focus of the entire process. The machine tool is processed according to the numerical control program. The correctness of the program directly affects the processing shape and processing accuracy. Most of the actual production uses automatic programming methods. Process it, it's best not to scrap it
After the programming is completed and before the formal cutting process, the CNC program should be checked and verified to determine its correctness. The numerical control system of the wire cutting machine tool provides a method of program verification. The commonly used methods are: one is the drawing inspection method, which is mainly used to verify whether there is an error grammar in the program and whether it conforms to the pattern processing contour; the other is the empty stroke inspection method , It can check the actual processing of the program, check whether there is collision or interference in the processing, and whether the stroke of the machine tool meets the processing requirements, etc., through the simulation of the dynamic processing situation, the program and the processing trajectory are fully verified. For some punching dies with high dimensional accuracy requirements and small matching gaps between convex and concave dies, you can first try cutting with a thin sheet to check the dimensional accuracy and matching gaps. If you find that it does not meet the requirements, you should modify the program in time until the verification is qualified Formal cutting processing. During processing, the electrical and non-electrical parameters can be adjusted according to the processing state, so that the processing can maintain the best discharge state. After the formal cutting is over, you should not rush to remove the workpiece, you should check whether the start and end coordinate points are consistent, if any problems are found, you should take "remedial" measures in time.