The Stamping Tool Design for Mechanical Movement

The requirements for the design of stamping dies are put forward through the analysis of the basic movements of various stamping processes. The basic concept of mechanical motion in the stamping process is first explained. Then the basic motion mechanisms of punching, bending, and drawing processes are analyzed item by item, pointing out what should be controlled in the mold design and introducing the methods and some examples of the flexible use of mechanical motion in the design of the mold. Finally, it summarises the methods of analyzing the product process motion according to specific situations. It emphasizes the importance of the control and flexible use of mechanical motion in mold design to improve the design level and ensure the quality of stamped parts.

Overview of mechanical movements in the stamping process

Cold stamping applies pressure to various sheets or blanks of different sizes, using a die and stamping equipment (press, also known as punch press) to deform or separate them and obtain parts of a certain shape or size, and performance. General production is carried out on vertical presses, thus determining that the main movement of the stamping process is up and down, in addition to the various mutual movements between the die and the sheet and the structural parts in the die. Mechanical movements can be divided into three basic forms of movement: sliding, turning and rolling, all of which are present in the stamping process, but each has different characteristics and has a different impact on stamping.

The main motion in the stamping process is up and down. Still, the design of tilting wedge structures, swivel pin structures, roller structures, and rotary cut structures in the die can transform the main motion into horizontal motion, rotation in the die, and rolling in the die accordingly. These special structures in the mold design are more complex and difficult, and the cost is also higher, but to achieve the shape and size requirements of the product, but not lose an effective solution.

The control and use of mechanical movements in a blanking die

The basic movement of the blanking process is that the unloading plate first makes contact with the sheet and presses it firmly, the convex die descends to make contact with the sheet and continues to descend into the concave die, the convex and concave die, and the sheet produces relative movement leading to the separation of the sheet. The convex and concave die separate, and the unloading plate pushes the workpiece or scrap off the convex die to complete the blanking movement. The movement of the unloading plate is very critical. To ensure the quality of the punch, the movement of the unloading plate must be controlled so that it is in contact with the plate before the die, and the pressing force must be sufficient. Otherwise, the cut-off surface of the punched part will be of poor quality, with low dimensional accuracy, poor flatness, and even reduced die life.

With the usual method of designing drop-in punching dies, separating the workpiece from the waste side is often difficult after punching. On the premise that the quality of the workpiece is not affected, it is possible to add some protruding limit blocks on the unloading plate of the convex and concave die so that after the movement of the drop punch is completed, the unloading plate of the concave die will first push out the workpiece from the concave die. Then the unloading plate of the convex and concave die will push down the waste from the convex and concave die so that the workpiece and the waste will also be separated naturally.

For larger stamped parts with local projections, the die unloading plate of the concave die of the drop punch can be increased with a pressing die. A sufficient spring force can be applied to ensure that when the pressing die on the unloading plate comes into contact with the plate material, the material is first deformed to achieve the pressing purpose, and then the drop punching movement continues. There is a simple method; the punching machine uses different lengths of 2 to 4 batches of punches. The punching lets punching movement in time can effectively reduce the punching force.

The control and use of mechanical movement in the bending die

The basic movement of the bending process is the unloading plate first contact with the plate material and pressed to death, the convex die down to contact with the plate material, and continues to fall into the concave die, convex, concave die, and plate material to produce relative movement, resulting in deformation of the plate material bending, and then convex, concave die separation, bending concave die on the top bar (or slider) to bend the edge of the push out, to complete the bending movement. The unloading plate and the movement of the top bar are very critical. To ensure the quality of bending or production efficiency, one must first control the movement of the unloading plate so that it is in contact with the plate material before the convex die, and pressure material force must be sufficient. Otherwise, the bent size accuracy is poor, with bad flatness; secondly, it should ensure that the top bar force is sufficient to push out the bent parts smoothly. Otherwise, the bent parts deform, resulting in low production efficiency. For high precision requirements of the bending parts, one should pay special attention to one point, preferably in the bending movement, to have a movement dead point; that is, all relevant structural parts can touch dead.

Some workpiece bending shape is more peculiar, or bend after the normal way from the concave die off, then often need to use the tilt wedge structure or pin structure; for example, the use of tilt wedge structure can be completed in less than 90 degrees or back hook type bending, the use of pin structure can be achieved once the cylinder parts.

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