The process before and after TD treatment of the i

2022-07-30
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The process of stamping and drawing die insert before and after TD treatment

during the development of stamping die, it is often encountered that parts in the drawing process are strained. For thin plate parts, methods such as chromium plating, nitriding, such as compound mortar insulation system nitrogen, laser quenching, PVD, etc. can be used to improve the shape, hardness and finish to solve the problem of strain. However, for high-strength thick plate parts, the methods listed above cannot meet the requirements of mass production for coating durability. Therefore, in order to prolong the service life of the coating and reduce the frequency of coating, TD treatment is generally considered for the drawing insert

td treatment is to place the workpiece in the molten borax mixture and form a metal carbide coating with high hardness, wear resistance, tensile damage resistance and corrosion resistance by diffusion at high temperature (850 ~ 1050 ℃). As TD treatment is a high-temperature treatment process, it will inevitably produce thermal stress and accompanied by phase transformation process. The result of phase transformation will form changes in tissue stress and specific volume of workpiece. The consumption of these factors will exceed 70million tons, which will cause deformation or even cracking of workpiece. This deformation will directly lead to difficulties in assembly or commissioning of inserts after TD treatment

in order to compensate the deformation caused by TD treatment, the process before and after TD treatment is particularly important. This paper synthesizes the practical experience of several stages in the process of mold development, and summarizes some precautions before and after TD treatment

1 after the completion of TD treatment in the design stage, it is generally necessary to carry out lapping for each fit of the insert. Due to the high hardness, the workload of bench worker lapping is very large and time-consuming. Therefore, in the mold design stage, it is necessary to start to consider how to reduce the workload of fitter lapping, which can not only shorten the commissioning period, but also save costs

in the design stage, it is generally necessary to pay attention to the following points:

(1) the overlap part of the side wall of the blank holder insert should be kept as little as possible. Generally, the width of about 40 mm can be considered, and the rest parts should be designed with 0.5 ~ 1.0 mm Jenning, so as to reduce the product of the research:

(2) when dividing the insert, the thickness of the insert in all directions should be as uniform as possible, In this way, the torque at 1 fixed angle can be detected to reduce the deformation of the insert:

(3) the positioning method of key + pin can be used as much as possible, and the method of determining whether to use the pin hole insert on the insert according to the actual process level can be used to avoid the problem that the

pin cannot be driven after the pin hole on the insert changes in the later stage:

(4) finally, the seam line of the insert needs to be 10 ° away from the material flow direction. If the seam line does not meet these requirements, it is easy to see strain near the seam line

2 Dittmar of the assembly stage

td treatment explained: "after adding this kind of inlay, it is necessary to reassemble the insert. However, due to the high temperature treatment will produce thermal stress and structural transformation, it is also necessary to carry out research and matching. Therefore, during assembly, the following points should be paid attention to:

(1) the edges of the pin holes and screw holes of the insert must be chamfered:

the bottom and sides of the insert must be well colored with red lead (more than 80% is generally considered, and the insert is at the bottom and cannot be easily rotated on the bench bench), as shown in Figure 1. The bottom lapping rate of the insert is not up to standard, and it is difficult to ensure the consistency of the shape during the repeated disassembly and assembly of the insert:

(3) in addition, attention should be paid to ensure that the fit between the insert and the insert is zero

3 machining stage

td treatment also has certain requirements on machining process sequence, machining allowance, clearance and surface finish of insert:

(1) during rough machining of insert, 0.15 ~ O.3 mm machining allowance shall be reserved, and then finish machining shall be carried out after overall heat treatment:

(2) during heat treatment of insert, it is better to be in the same factory as the later TD treatment:

(3) after heat treatment, it is necessary to re grind the bottom and side of insert, Ensure that the screw hole and pin tljq are surrounded by red lead and insert bottom, and the fitting rate is more than 80%, and the insert bottom cannot be easily rotated on the bench bench:

(4) ensure that the gap between the connection between the insert and the insert and the support is zero, and the connection is free of scars:

(5) after finishing, it is necessary to round the edge of the insert joint again by O.2 ~ 0.3 m, and the surface roughness of the die should reach O.5 ~ 113

after the lapping rate of the upper and lower moulds reaches more than 85%, the strip lapping shall be carried out. Before machining the stop die, it is better to make a set of soft die to grasp the springback compensation, so as to avoid repeated cutting and machining of the insert of the stop die, which not only increases the cost, but also sometimes causes the die insert to be scrapped and delays the project period

4 treatment after debugging

after debugging, it is necessary to select some inserts for TD treatment, which can be carried out step by step or in different regions. For example, TD the blank holder before processing the die. In most cases, punch can be considered not to be processed, which can effectively control the risk after TD processing. Silicon steel sheet can be added to adjust the steps that cannot be solved after multiple lapping of the bottom and the side wall after treatment

the steel deformation of L ≤ 300 mm after insert quenching and TD treatment generally needs to be controlled within 0.1 MRN. The TD treatment manufacturer needs to make necessary adjustments to the insert size after TD treatment, otherwise it will cause great difficulties in the splicing of the insert after TD. The joint between TD inserts generally needs to be 0.05mm. If the joint a is large (as shown in Figure 2), obvious joint marks will be left on the parts (as shown in Figure 3). This kind of trace is difficult to eliminate in the later commissioning, and will also affect the service life of TD coating.

5 conclusion

to sum up, the Countermeasures for TD treatment deformation run through the whole process of mold development. From the process design stage, it is necessary to start to consider the possible deformation caused by TD treatment, and add corresponding control points at different stages, so as to reduce the risk of TD treatment and commissioning delay

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