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1, under normal circumstances
When the punch shape is regular, the wire cutting process often leaves the connection part (pause point, which is a small section of the cutting trajectory reserved for the workpiece not completely separated from the blank after the first rough cutting). In position, most of the cuts are completed, and only one cut is made for the reserved connecting portion. Afterwards, it is trimmed by the fitter, which can reduce the processing cost of the punch die cut in the middle wire cut. Due to the high hardness and narrow shape of the material, the carbide punches lead to slow processing speeds and are easily deformed. Especially in the case of irregular shape, the dressing of the connection part is difficult for the fitter. Therefore, in the middle wire cutting process, appropriate adjustments can be made to the process, so that the dimensional accuracy can be achieved and the grinding process of the pause point before the fitter assembly can be eliminated. Due to the high hardness of the hard alloy and the large thickness of the cut, the machining speed is slow and the torsional deformation is severe. Most of the machining of the profile and the preparation of the connection part (pause point) are performed by four cutting methods and the cutting parameters and offsets of the two parts are The same amount of Offset. The offset of the first cutting wire (molybdenum wire) is increased to 0.15-0.18mm so that the work piece can fully release the internal stress and complete torsional deformation. In the next three times, there can be enough margin for the fine cut processing. The final size of the workpiece is guaranteed.
The specific process analysis is as follows:
(1) A Φ1.0-Φ1.5mm threading hole is pre-machined with a piercing machine or an EDM machine at an appropriate position of the blank. The length of the introduction cutting line between the center of the threading hole and the contour line of the punch is 5-10 mm.
(2) The width of the contour of the punch and the edge of the blank shall be at least 1/5 of the thickness of the blank.
(3) The connection part reserved for subsequent cutting (pause point) should be selected close to the center of gravity of the workpiece blank, and the width should be 3-4mm (depending on the workpiece size).
(4) In order to compensate for the torsional deformation, most of the residual deformation is left in the first rough cutting stage, and the offset is increased to 0.15-0.18 mm. Subsequent three times using the fine cut method, because the cutting margin is small, the deformation is also reduced.
(5) After most of the four cutting operations are completed, the workpiece is blown dry with compressed air. Then, the end face of the blank is washed with an alcohol solution, dried and then dried with an adhesive or liquid quick-drying adhesive (usually 502 quick-drying Glue) Grind the thinned metal sheet with a thickness of about 0.3 mm on the blank, and then cut the reserved part of the workpiece at the offset of the original 4 times (Note: Do not put the glue droplets to the reserved part of the workpiece. Connect parts so as not to cause non-conductivity and cannot be processed).
2. Deformation analysis in concave template processing
Before the on-line cutting process, the template has been cold-worked and hot-worked. The internal residual stress has been generated and the residual stress is a relatively balanced stress system. When the on-line cutting removes a large amount of waste, the stress is destroyed along with the balance. Release it. Therefore, during on-line cutting of the template, with the influence of the original internal stress and the processing thermal stress generated by the spark discharge, an irreversible and irregular deformation will occur, so that the thickness of the rear cutting blade will be uneven and the impact will be uneven. The processing quality and processing accuracy. In view of this situation, a template with a relatively high accuracy is generally used for cutting four times. The first cut cuts the waste of all the holes, removes the waste, and then completes the second, third, and fourth cuts by the machine's automatic shift function. a cutting the first time, taking waste → b cutting the first time, taking the waste → c cutting the first time, taking the waste →... → n cutting the first time, taking the waste → a cutting the second time → b cutting the second time →...→→n cut 2nd→a cut 3rd→→→n cut 3rd→a cut 4th→...→n cut 4th time, processing is completed. This kind of cutting method can make each hole have sufficient time to release internal stress after machining, and can reduce the mutual influence and trace distortion caused by different types of holes due to different processing sequences to the minimum, and ensure the processing size of the template better. Accuracy. However, the processing time is too long, the number of threadings is large, and the workload is large, which increases the manufacturing cost of the template. In addition, the machine itself creeps with the processing time and temperature fluctuations. Therefore, according to the actual measurement and comparison, the template can be used for the first time to process the scrap without changing the accuracy of the processing, and the next 2, 3, and 4 times for cutting (ie, cutting a 2nd After that time, do not shift, do not remove the wire, immediately cut 3rd, 4th → b → c ... → n), or save the 4th cut and do 3 cuts. After such cutting, the size of the shape basically meets the requirements. This not only improves the production efficiency, but also reduces the labor, so it also reduces the manufacturing cost of the template.
3, concave template hole small corner processing technology
As the diameter of the wire electrode (molybdenum wire) is selected, the radius of the corner hole of the cut hole is also larger. When the corner radius of the template hole is very small (such as R0.07-R0.10mm), you must change the filament (such as Φ0.10mm). However, with respect to thick filaments, the filaments are processed at a slower speed and are easily broken. If the entire hole is processed with filaments, the processing time will be prolonged and wasteful. After careful comparison and analysis, we first adopted a proper increase in the radius of the corners, cutting all the holes with coarse wire to meet the dimensional requirements, and then replacing the corners of the holes to achieve the specified dimensions. However, the replacement of Φ0.10mm of the filament needs to be re-aligned center, and the coordinate of the re-alignment center and the original center coordinate value should be about 0.02mm.
Carbide tooth profile cutting process: