When performing wire cutting, how to ensure the quality of wire cutting is a matter of great concern when processing the die. In general, the following aspects should be noted when cutting online.
(1) Select suitable mold materials
Wire cutting processing is generally carried out after the billet is hardened. For example, carbon tool steel such as T8A and T10A is used. Because it is difficult to harden, the hardened layer is shallow, and the hardened layer may be worn away after grinding. Decreased significantly. In order to improve the service life and machining accuracy of wire-cutting dies, alloy tool steels or hard alloys with good hardenability should be used. The hardness of these materials from the surface to the center is not significantly reduced.
(2) Improve mechanical transmission accuracy
The mechanical transmission accuracy has a great influence on the machining accuracy, and the displacement accuracy of the table and the movement accuracy of the wire directly affect the machining accuracy. Since the movement of the table is driven by a plurality of transmission pairs, such as gear pairs, screw nut pairs, etc., their transmission accuracy directly affects the machining accuracy. The movement accuracy of the wire is also greatly affected by the rotation accuracy of the guide wheel, the uneven wear of the guide wheel, and the slack of the wire. It can be seen that the low precision of the mechanical transmission has a great influence on the processing quality.
(3) Reducing residual stress
When cutting with a wire, the large piece of metal is cut, and the relative equilibrium state of the internal residual stress of the material is destroyed, and the stress is redistributed. The residual stress in the material is sometimes more serious than the machine tool accuracy and other factors on the machining accuracy, so that the deformation can be macroscopically visible, and even the material will rupture during the cutting process. In order to reduce the deformation caused by residual stress, corresponding measures should be taken. For example, the heat treatment specification should be correctly selected; the contour of the workpiece should be 8-100mm from the edge of the blank; before the online cutting, the aging treatment can be performed; before the quenching, the pre-processing is performed to remove most of the The remaining amount; when performing wire cutting, the second cutting method is adopted, the first rough-cutting hole is used, and the cutting hole is refined when the stress reaches a new balance; the correct cutting sequence is selected. The above measures are of great benefit in reducing the residual stress in the material.
(4) Reduce the surface roughness
The surface roughness of the mold cavity has a great influence on the quality of the plastic parts. At the time of cutting, the idea should be to reduce the surface roughness. To this end, relevant measures should be taken. If the wire is not tight enough, it should be tensioned at any time; the feed rate should be adjusted appropriately to avoid the fluctuation of the speed; if the mechanical transmission gap is too large, the wire will be shaken and the roughness will be increased. Large, for this purpose, it is necessary to adjust the tightness of each mechanical transmission part in time; correctly select the electrical parameters to avoid excessive single pulse. In addition, the wire speed of the wire is too fast or shakes, which also affects the surface roughness of the part. They are not good for quality improvement.
(1) Select suitable mold materials
Wire cutting processing is generally carried out after the billet is hardened. For example, carbon tool steel such as T8A and T10A is used. Because it is difficult to harden, the hardened layer is shallow, and the hardened layer may be worn away after grinding. Decreased significantly. In order to improve the service life and machining accuracy of wire-cutting dies, alloy tool steels or hard alloys with good hardenability should be used. The hardness of these materials from the surface to the center is not significantly reduced.
(2) Improve mechanical transmission accuracy
The mechanical transmission accuracy has a great influence on the machining accuracy, and the displacement accuracy of the table and the movement accuracy of the wire directly affect the machining accuracy. Since the movement of the table is driven by a plurality of transmission pairs, such as gear pairs, screw nut pairs, etc., their transmission accuracy directly affects the machining accuracy. The movement accuracy of the wire is also greatly affected by the rotation accuracy of the guide wheel, the uneven wear of the guide wheel, and the slack of the wire. It can be seen that the low precision of the mechanical transmission has a great influence on the processing quality.
(3) Reducing residual stress
When cutting with a wire, the large piece of metal is cut, and the relative equilibrium state of the internal residual stress of the material is destroyed, and the stress is redistributed. The residual stress in the material is sometimes more serious than the machine tool accuracy and other factors on the machining accuracy, so that the deformation can be macroscopically visible, and even the material will rupture during the cutting process. In order to reduce the deformation caused by residual stress, corresponding measures should be taken. For example, the heat treatment specification should be correctly selected; the contour of the workpiece should be 8-100mm from the edge of the blank; before the online cutting, the aging treatment can be performed; before the quenching, the pre-processing is performed to remove most of the The remaining amount; when performing wire cutting, the second cutting method is adopted, the first rough-cutting hole is used, and the cutting hole is refined when the stress reaches a new balance; the correct cutting sequence is selected. The above measures are of great benefit in reducing the residual stress in the material.
(4) Reduce the surface roughness
The surface roughness of the mold cavity has a great influence on the quality of the plastic parts. At the time of cutting, the idea should be to reduce the surface roughness. To this end, relevant measures should be taken. If the wire is not tight enough, it should be tensioned at any time; the feed rate should be adjusted appropriately to avoid the fluctuation of the speed; if the mechanical transmission gap is too large, the wire will be shaken and the roughness will be increased. Large, for this purpose, it is necessary to adjust the tightness of each mechanical transmission part in time; correctly select the electrical parameters to avoid excessive single pulse. In addition, the wire speed of the wire is too fast or shakes, which also affects the surface roughness of the part. They are not good for quality improvement.
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