Abstract: In the stamping process, mechanical movement runs through. The realization of various stamping processes has its basic motion mechanism, which is closely related to the die. The structural design and mechanical design of various molds are ultimately to meet the requirements of realizing specific actions. Whether the designed die can strictly complete the movement required to realize the stamping process directly affects the quality of stamping parts, so the mechanical movement should be controlled in the die design. At the same time, in order to meet the requirements of product shape and size, we should not stick to or be limited to the basic movement modes of various processes, but should constantly develop and innovate and flexibly use mechanical movement in mold design. Abstract: In the stamping process, mechanical movement runs through. The realization of various stamping processes has its basic motion mechanism, which is closely related to the die. The structural design and mechanical design of various molds are ultimately to meet the requirements of realizing specific actions. Whether the designed die can strictly complete the movement required to realize the stamping process directly affects the quality of stamping parts, so the mechanical movement should be controlled in the die design. At the same time, in order to meet the requirements of product shape and size, we should not stick to or be limited to the basic movement modes of various processes, but should constantly develop and innovate and flexibly use mechanical movement in mold design.
Keywords: stamping die design, flexible application of mechanical motion control
1. Introduction
Based on the basic theory of stamping process, this paper puts forward the requirements for stamping die design by analyzing the basic actions of various stamping processes. Firstly, the basic concept of mechanical motion in stamping process is expounded, then the basic motion mechanism of blanking, bending and drawing process is analyzed item by item, the contents that should be controlled emphatically in die design are pointed out, and the flexible application methods and some examples of mechanical motion in die design are introduced. Finally, the method of analyzing product process movement according to the specific situation is summarized, and it is emphasized that controlling and flexibly applying mechanical movement in die design is of great significance to improve the design level and ensure the quality of stamping parts.
2. Overview of mechanical movement in stamping process
Cold stamping refers to stamping various kinds of plates or blanks with different specifications through dies and stamping equipment (press, also known as punch) to deform or separate them to obtain parts with certain shape, size and performance. Vertical punch is generally used in production, which determines that the main movement in the stamping process is up and down movement. In addition, there are various mutual movements between the die and the sheet metal and the structural parts in the die.
Mechanical motion can be divided into three basic forms: sliding, rotating and rolling, which all exist in the stamping process, but each form has different characteristics and different influences on stamping.
Because there are many kinds of movements in stamping process, all kinds of movements should be strictly controlled in stamping die design to meet the requirements of die design. At the same time, in the design, we should flexibly use various mechanical movements according to specific conditions to meet the requirements of products.
The main movement in the stamping process is up and down movement, but by designing the wedge structure, pin structure, roller structure and rotary cutting structure in the die, the main movement can be transformed into horizontal movement, rotation in the die and rolling in the die. These special structures are complex, difficult and expensive in mold design, but they are effective solutions to meet the requirements of product shape and size.
3. Control and application of mechanical motion in blanking die.
The basic action of blanking process is that the stripper first contacts and compresses the sheet, and the punch descends to contact the sheet, and then continues to descend into the female die. The punch, the die and the sheet metal move relatively, which leads to the separation of the sheet metal, and then the punch and the die are separated, and the stripper pushes the workpiece or waste away from the punch to complete the blanking movement. The movement of stripper is very important. In order to ensure the blanking quality, it is necessary to control the movement of the stripper, and contact with the sheet before blanking, and the pressing force should be sufficient, otherwise the cutting surface quality of the blanking part will be poor, the dimensional accuracy will be low, and the flatness will be poor, and even the die life will be shortened.
According to the usual method to design blanking and punching dies, it is often difficult to separate the workpiece from the waste edge after stamping. On the premise of not affecting the quality of the workpiece, some raised limit blocks can be added to the punch plate, so that after the blanking and punching movements are completed, the punch plate pushes the workpiece out of the die first, and then the punch plate pushes the waste out of the punch plate, so that the workpiece and the waste are naturally separated.
For some large-scale stamping parts with local bulges, a blanking punch can be added to the die discharging plate of blanking and punching die, and at the same time, enough spring force can be applied to ensure that when the blanking punch on the discharging plate contacts with the sheet metal, the material will deform first to achieve the pressing purpose, and then the blanking and punching movement will continue, which can often reduce the number of dies and reduce the cost in one step.
Some stamping dies have a large number of punching holes, which requires a lot of punching force, which is not conducive to stamping production and even does not have enough tonnage punches. There is a simple method, that is, using 2 ~ 4 batches of punches with different lengths, so that the punching movement can be carried out in time, which can effectively reduce the punching force.
For those stamping parts with holes with high position accuracy on the curved surface (such as the concentricity of two holes bent on the opposite side, etc.) ), if you punch first and then bend, it is difficult to meet the requirements of hole location. It is necessary to design a wedge-shaped structure, punch holes after bending, and use horizontal punching movement to achieve the goal. There are strict requirements for the height of flanging and drawing, and similar structural design can be adopted if trimming is needed.
4. Control and application of mechanical motion in bending die
The basic movement in the bending process is that the stripper first contacts the sheet and the die, the punch descends to contact the sheet and continues to descend into the female die, so that the sheet is deformed and bent, and then the punch and the female die are separated, and the ejector pin (or slider) on the bending female die pushes out the bending edge to complete the bending movement. The movement of stripper and ejector pin is very important. In order to ensure the bending quality or production efficiency, it is necessary to control the movement of the stripper to make it contact the sheet before the punching machine, and the pressing force must be large enough, otherwise the dimensional accuracy and flatness of the bent parts will be poor. Secondly, it is necessary to ensure that the ejector pin is strong enough to push out the bending part smoothly, otherwise the bending part will be deformed and the production efficiency will be low. Special attention should be paid to curved parts with high precision. The bending motion preferably has a dead point, that is, all related structural components can collide.
Some workpieces have strange bending shapes, or they can't be separated from the mold normally after bending. At this time, it is often necessary to use a wedge structure or a pin structure. For example, the inclined wedge structure can complete bending or bending back less than 90 degrees, and the pin structure can realize one-time molding of cylindrical parts.
It is worth mentioning that for some shell parts, such as the computer floppy drive shell, due to the long bending edge, there is sliding between the elbow and the plate, and it is easy to wipe off dander when bending, and the galvanized layer of the material falls off, so the effect of frequent polishing, bending and punching is not ideal. The usual practice is to plate a layer of titanium on the bending punch to improve its smoothness and wear resistance; Or a roller is embedded in the corner r of the bending punch to convert the bending sliding between the elbow and the sheet into rolling. Because the friction of rolling is much smaller than sliding, it is not easy to scratch the workpiece.
Not completely accurate, for reference only, please learn by yourself.
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