The slow-cut wire cutting machine is widely used and important. In the production process of plastic mold and fine multi-station progressive die, it can ensure good scale accuracy, directly affect the assembly precision of the mold, the precision of the part and the mold. Use life and so on. Because the precision of the workpiece is high, if it is neglected in the process, it will cause the workpiece to be scrapped, and it will also have a negative impact on the production cost and processing cycle of the mold.
In the process of programming and operation of slow wire cutting machine, combined with years of production practice, several process treatment methods and processing operations are summarized for the deformation problems and difficulties encountered in the process.
2 punch processing technology
The punch plays an important role in the mold. Its design shape, dimensional accuracy and data hardness directly affect the punching quality, service life and precision of the stamping. In the practice of production and processing, because of the residual stress deformation inside the workpiece blank and the thermal stress deformation caused by the discharge, the threaded hole should be processed first to perform the closed cut, and the open cut can be avoided as much as possible. If it is limited by the blank size of the workpiece and cannot be cut in the closed form, for the square blank, the cutting path (or the cutting direction) should be selected when programming.
Cutting the road should be beneficial to ensure that the workpiece remains in the same coordinate system as the fixture (clamping support) during the machining process, avoiding the effects of stress deformation. The clamp is fixed at the left end, and is cut from the left side of the gourd-shaped punch in a counterclockwise direction, and the entire blank is divided into two parts according to the cut road. Because the data on the left and right sides of the connecting blank is cut more and more small, the right side of the blank is gradually separated from the jig, and the internal residual stress cannot be resisted and the workpiece is deformed. If cut in a clockwise direction, the workpiece remains on the left side of the blank, close to the clamping position, and most of the cutting process keeps the workpiece and the fixture in the same coordinate system, and the rigidity is good, and stress deformation is avoided. Under normal conditions, a reasonable cutting of the road should separate the workpiece from the clamping part.
The segment is arranged at the end of the total slitting procedure, leaving the bridge at a position close to the grip end of the blank.
The following is a partial analysis of the cutting process of the carbide toothed punch. Under normal conditions, when the shape of the punch is regular, the line cutting process will usually reserve the joint part (the pause point, which is a small section of the cut that is reserved for the workpiece to be completely separated from the blank after the first rough cut. The trajectory line is left in the plane orientation. After most of the finishing cuts, the reserved joints are cut only once, and then trimmed by the fitter, which can reduce the processing cost of the punch on the slow wire cutting. .
Due to the high hardness and long shape of the data, the cemented carbide punch has a slow processing speed and is easily deformed. Especially in the case of irregular shape, the repair of the reserved portion brings great difficulty to the fitter. Therefore, the process can be properly adjusted during the cutting process of the slow wire cutting, so that the dimensional accuracy of the profile reaches the requirement, and the grinding process of the pause point before the fitter assembly is eliminated.
Because the hardness of the cemented carbide is high, the cutting thickness is large, the processing speed is slow, and the deformation is severe. The processing of most shape processing and reserved joints (pause point) adopts 4 cutting methods and the cutting parameters of the two parts. And offset (Offset) are common. The first cut of the electrode wire is increased to 0.5-0.8mm, so that the workpiece can fully release the internal stress and completely change the deformation. At the back three times, the allowance can be used for the finishing process, so that the final dimension of the workpiece can be obtained. Be assured.
The specific process is analyzed as follows:
(1) Pre-cut the Φ1.0-Φ1.5mm threading hole in the proper orientation of the blank by punching machine or EDM machine, and introduce the length of the imported cutting line between the center of the threading hole and the convex line. 10mm.
(2) The outline of the punch and the width of the edge of the blank shall be at least 1/5 of the thickness of the blank.
(3) The joint part (pause point) reserved for the subsequent cutting shall be selected close to the center of gravity of the workpiece blank, and the width shall be 3-4 mm.
(4) In order to compensate for the deformation, the majority of the residual deformation is left in the first rough cutting stage, and the offset is increased to 0.5-0.8 mm. The subsequent three-time selection of the fine cutting method, because the cutting allowance is small, the deformation amount is also reduced.
(5) After most of the shape is cut and finished 4 times, the workpiece is blown dry with compressed air, then the end face of the blank is washed with alcohol solution, dried, and then the adhesive or liquid quick-drying glue is used. Dry glue) The metal foil with a thickness of about 1.5mm smoothed by the grinding machine is fixed on the blank, and then the reserved joint portion of the workpiece is cut according to the original 4 times offset (Note: Do not drop the glue into the water nozzle) Or drip onto the reserved joint portion of the workpiece to avoid causing non-conductivity and processing.
3 Deformation analysis in the processing of concave stencil
Before the in-line cutting process, the template has been cold-worked and hot-processed, and a large residual stress has occurred inside, and the residual stress is a relatively balanced stress system. When the wire is cut open to remove a lot of waste, the stress is balanced with the balance. Disrupted and released. Therefore, when the template is cut in-line, the non-directional and irregular deformation will occur due to the influence of the original internal stress and the processing thermal stress generated by the spark discharge, so that the thickness of the cutting edge is uneven. , affecting the processing quality and processing accuracy.
For this kind of situation, for the template with higher precision requirements, 4 times of cutting processing is generally used. The first cut cuts off the waste of all the holes, removes the waste, and then the machine moves and takes the initiative to thread, and finishes the second, third, and fourth cuts. a cut the first time, take the waste → b cut the first time, take the waste → c cut the first time, take the waste → ... → n cut the first time, take the waste → a cut the second time → b cut the second time →...→n cut the second time→a cut the third time→...→n cut the third time→a cut the fourth time→...→n cut the fourth time The processing is over.
This cutting method can make the internal stress of each type of hole after the processing is satisfied, and can reduce the mutual influence and micro-deformation of each type of hole due to the different processing order, and ensure the processing of the template better. Scale accuracy. However, such processing time is too long, and the consumption of consumable parts of the machine tool is large, which increases the production cost of the template. In addition, the machine itself will creep as the machining time is extended and the temperature is shaken. Therefore, according to the practice measurement and comparison, the template can be used to take the first common processing to take the waste without the processing precision, and the second, third, and fourth times behind can be cut together (ie, a cut) After the second time, no shifting, no wire cutting
Then cut the 3rd, 4th → b→c...→n), or save the 4th cut and do 3 cuts. After the cutting is completed, the shape and shape are basically in accordance with the requirements. See Table 1 and Table 2 for the reference values of machining allowance, machining accuracy and appearance roughness for each of the 4th and 3rd cuts. Initial budget, the displacement between the holes, threading, wire cutting, water, water, etc. are calculated according to 1min. Using this cutting method, processing a template with 100 holes, each time will save about 9h of processing time, cut 4 times and save about 30h, so that the expensive machine can be used to cut the machine In terms of both the production power and the cost reduction, the cost of the template is also reduced.
4 concave template hole small corner processing technology
Because the diameter of the selected slit wire is larger, the radius of the corner of the cut hole is larger. When the corner radius of the template hole is very small (such as R0.07-R0.10mm), the filament (such as Φ0.10mm) must be used. However, in the case of thick yarns, filament processing is slower and more expensive (mostly imported yarns are required). If the entire hole is machined with filaments, it will prolong the processing time and cause dross. After careful comparison and analysis, the adoption first increases the corner radius properly, cuts all the holes into the scale requirements with the thick wire, and replaces the filaments to repair the corners of all the holes to the rule scale.
The following is a line cutting process for a rectangular toothed concave template (with a radius of the inner corner of R0.07 mm).
(1) Firstly, the template hole is machined to the required size by Φ0.20mm, and the inner corner is processed to R0.15mm.
(2) Demagnetization, shutdown.
(3) Replace the Φ0.10mm filament. Move the cut wire conveyor belt to an unused position. If the conveyor belt has been used in three orientations and the effect of the biting filament is unsatisfactory, replace the new conveyor belt.
(4) Find the center from the beginning. The cutting wire guide insert with 2 diamond cones (this guide insert is specially used by AGIE's slow wire cutting machine). The point support enables the lower deflection point of the cut wire to be accurately positioned, so that the cut wire is accurate. Guide the ground. When the cut wire diameter is Φ0.20mm, the center is found at point b, and when the cut wire diameter is Φ0.10mm, the center is found at point a, |ab|=|bo|-|ao|=0.1 KF (〗 〖KF) -0.05 〖KF (〗 〖KF)〗 = 0.0707mm. Therefore, the coordinate value of the aligning center of the Φ0.10mm filament should be replaced by about 0.0707mm from the original center coordinate value.
(5) Modify the radius of the graphic fillet, program from the beginning, avoid the other type of hole summary line, and trim the corner radius of the hole to R0.07mm.
5 Processing order of multi-hole die, fixed plate and stripper
The multi-hole die, the fixed plate and the unloading plate take into account the small deformation caused by the residual stress and the processing heat during the processing, so in the practice of production, the method of selecting the hole processing order is common to ensure the type. The commonality of the hole orientation deformation ensures the concentricity of the die, the fixed plate, and the discharge plate type hole.
The slow-cut wire cutting machine has high processing precision and strong function, but the processing cost is high. If you want to fully play the role of the machine tool and create good economic benefits, you must carry out reasonable processing analysis and technical function analysis of the workpiece, and fully understand the machine tool. Structural function and proficiency in the operation skills of the machine tool, rational selection of water parameters and electrical parameters, reducing the state of broken wire in the process of processing, and constantly summing up lessons learned in practice, so as to maximize the potential of the machine tool and improve production power.
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