1) Clear angel wire cut processing method using molybdenum wire or brass wire
(I) The processing method for punch punching are relatively simple. When cutting to the top of the corner, continue to cut forward along the original cutting direction by a certain distance (approximately 0.5 mm longer cutting length), then use this distance (approximately 0.5 mm) as a radius, and follow the arc to the other side of the corner. After continuing processing, a small radius R of 0.10mm clear angle can be obtained. If the requirement of radius of the small arc of the clear corner is not particularly high, it can also be stopped when reaching the highest point to the corner vertex, continue the discharge machining for several seconds. (Usually 2s ~ 3s), and then transferred to the next program, this way can also get a clear corner that is not obvious.
( 2 ) It is difficult to clean the internal cavity of a part such as a die, and it is generally not allowed to use a method of extending the cut length to trim the corner, instead, the method is to stop the feed after machining to a predetermined position (inside corner). Continue to discharge machining for a few seconds, thus removing the impact of the electrode wire due to the discharge force after the corner is removed. At this time the small fillet radius will generally be greater than 0.3mm because it is constrained by the wire radius and discharge gap. In some occasions with high clear corner radius requirements, the following technological measures can also be taken:
①Reducing the discharge pulse and selecting the smaller diameter electrode molybdenum wire gold 0.08mm or brass wire processing.
② Extend the processing length properly. usually after processing to the vertex angle, continue to advance 0.02 mm ~ 0. 03mm, and use the arc transition method to transition to the next processing stage. If the continuation of the processing length is too large (such as 0. 05mm or more) , it is easy to cause marks in the corners, which easily lead to broken of die in use due to the concentration of stress.
③ tighten the electrode molybdenum cutting wire or brass wire to reduce the deflection of the flexible wire caused by the discharge force. People may also use molybdenum wire holder.
2) Process method for controlling the verticality and position accuracy of machined parts
(l) Tighten the electrode wire （molybdenum wire or brass wire）to ensure that the electrode wire has a certain tension, and then correct the verticality of the electrode wire (see “2. Correcting the verticality of the electrode wire” in 4.2.3). When the die is processed by the spark wire cutting method, the verticality of the cavity is of first importance, and then the cavity is used as a reference. As long as the verticality of the hole of the cavity of the wire cutting can be guaranteed, the verticality of the cavity embedded in the wire cutting process can also be guaranteed.
(2) Check the two-way positioning accuracy of the wire cutting machine and remove the burrs and impurities of the workpiece, use a tightly threaded electrode after clamping, so it can find the reference center automatically. In the jumping process, record the coordinates of the position of each step in order to check the accuracy of the broken wire. In general, only the accuracy of the two-way positioning of the machine tool can be ensured, and the position accuracy of wire-cut WEDM using molybdenum wire or brass wire can be controlled.
3 ) Processing method of controlling the matching precision of punch and die
(1) The commonly used processing method is to machining the punch and the die separately. By ensuring their dimensional accuracy and positional accuracy, the accuracy of matching the punch and the die can be controlled. However, the radius of the small round corner of the punch is generally small, and the radius of the small round of the corner of the concave die is larger. The cooperation between the two is a difficult problem. When using EDM to cut, the radius of the inner corner of the die must be determined according to the design requirements of the product, and then the radius of the small radius of the convex die should match it.
(2) The relatively simple process is to position the male and female templates with the guide post bushings and then cut them together. In this way, even if there is a certain deviation in finding the center or there is a deviation in the perpendicularity of the electrode molybdenum wire china during WEDM process, the matching accuracy between the male die and the female die will not be affected.
If the above punch and die are used for wire-cut electrical discharge machining, factors such as the correct datum, the verticality of the electrode wire, and the step error will affect the accuracy of the punch and the die, and even produce burr on the product.
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