There are various forms of tearing and inclination during the forming process of the intermediate protective bracket. The tearing parts are mainly distributed in the hole pattern of the workpiece, the junction of the R arc and the wall neck at the corner of the side wall, etc., due to stamping forming and production. Due to the difference in process conditions, the proportion of each fracture site is different. The tearing can be a one-time forming tear, or it can be a tear caused by the development of fatigue cracks, that is, invisible cracks.
Analysis of the reasons, according to the actual situation of the site, after checking the tearing part, fracture shape and crushing degree of the part, it is believed that the tearing and tilting behavior of the part is mainly reflected in the flanging forming process, and the reasons for this process phenomenon are as follows. :
1. The forming process parameters are not in place. During the forming process of the part, the process requires that the die, the pressing core and the parts of the two must be closely attached to the table, and the pressing plate material is plastically deformed when the slide of the machine tool slides down. achieve shape. But now because of the defects of unstable quality of the limited parts, it is clear that the pressure of the machine tool is in a state of unbalanced pressure beating during the production process.
The reason is that the processing technicians did not adjust the pressure of the machine tool in time at this stage according to the specified requirements of the process, or did not communicate with each other about the stability of the pressure of the machine tool at the time of each shift, resulting in poor quality of the parts. Safe.
2. Disadvantages of flanging forming mold design, this mold is shared by one mold and two-cavity left[/right part, because in addition to flanging, this process also includes shape forming content, and the parts are particularly miscellaneous, the curved surface is narrow, forming It is required that the die pressing material core is in line with the forming surface, etc., resulting in a large forming stroke and a small pressing material area under the structural conditions of the die. When planning the initial mold, the planners only considered the feature of the small binder surface, but ignored the forming and sliding stroke of the binder core.
There are the following planning shortcomings:
(1) The guide length of the pressing material core is planned to be 125mm, and the actual guiding length is 115 mm. Although it is within the planned range, the 115mm movement of the lifting part exceeds the effective guide length of 10mm, and the holding of the pressing material core is unstable, and the positioning of the parts is prohibited. ills.
(2) For the forming height of up to 115mm, a special guide plate needs to be planned. It cannot be guided by the gap between the machined surface and the side wall of the die. If it is not effectively eliminated, after mass production, the guide gap will increase due to long-term wear and tear, and the normal guiding function of the mold will be lost early, thus causing vicious quality accidents.
3. There is an error in the mold processing part and the drawing plan, such as clearly marking the area that needs to be processed to guide. However, because the pressing material core is a messy surface, the casting is selected to be formed and then the guide surface is machined, resulting in a gap error after the machined surface and the guide surface of the die are slipped. During the normal operation of the mold, the left / Swing right.
Before the part is formed, the positioning is carried out by the positioning pins and holes on the upper plane of the pressing material core, which requires the pressing material core to ensure stable, reliable and correct sliding during the forming of the part, otherwise the part will be damaged during forming. Instability, so that the pressing material core and the die wall collide and knead, resulting in tensile stress on the part. The parts are torn and tilted incorrectly.
In addition, if other factors are considered in the mold structure, and the special guide plate guide is ignored, there is a danger that the guide gap between the two parts will be damaged and cannot be correctly guided after the kneading conflict between the two parts is intense. Because the guiding gap of this structure is the debugging and sliding gap, once it is damaged, there will be no more effective adjustment methods, which will affect the forming quality of the part for a long time and bring about potential safety hazards.
Moreover, instead of using a special guide plate in the guide part, the guide structure of the machining profiles is used, which has the disadvantage that it cannot be adjusted after the gap is too large, which leads to the tearing and inclination of the parts.
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