Classification of metal stamping processes;
Stamping process can be roughly divided into two categories: separation process and forming process (bending, stretching and forming). The separation process is to make the stamping parts and blanks separate from each other along a certain contour line in the stamping process, and the quality of the separation section of the stamping parts should also meet certain requirements; The forming process is to make the stamping blank undergo plastic deformation without damage and transform it into the required finished product shape, and at the same time meet the requirements of dimensional tolerance.
According to the temperature of hot stamping, there are two ways: cold stamping and hot stamping. It depends on the strength, plasticity, thickness, deformation degree and equipment capacity of the material, and also considers the original heat treatment state and final use conditions of the material.
1, cold stamping metal processing at room temperature, generally suitable for blanks with thickness less than 4 mm. Its advantages are no heating, no scaling, good surface quality, convenient operation and low cost. The disadvantage is that there is work hardening phenomenon, which makes the metal lose its further deformation ability in severe cases. Cold stamping requires uniform blank thickness, small fluctuation range, smooth surface and no spots and scratches.
2. Hot stamping is a stamping method that heats metal to a certain temperature range. Its advantages are eliminating internal stress, avoiding work hardening, increasing the plasticity of materials, reducing deformation resistance and reducing equipment power consumption.
1. Die structure: Die is a tool for separating or deforming metal plates. It consists of an upper die and a lower die. The handle of the upper die is fixed on the slider of the punch and moves up and down with the slider, and the lower die is fixed on the workbench of the punch.
The punch and the die are the working parts of the die to deform or separate the blank, and they are fixed on the upper template and the lower template respectively through the pressure plate. The upper template and the lower template are respectively provided with a guide sleeve and a guide post to guide the alignment of the male die and the female die. The guide plate and the positioning pin are used to control the feeding direction and length of the blank respectively. The function of the discharge plate is to make the punched workpiece or blank separate from the punch.
2. Classification of stamping dies
Stamping die is an essential die in stamping production. Stamping dies can be basically divided into three types: simple dies, continuous dies and compound dies.
(1) Simple punch A simple punch is a punch that only completes one process in one stroke of the punch. It is a simple punching or punching die. During operation, the strip is fed between the two guide plates 9 on the female die until it touches the positioning pin 10. When the punch presses down, the punched parts (or wastes) enter the holes of the die, and the strip-shaped material clamps the punch and moves up with the punch. When the strip hits the stripper plate 8 (fixed on the female die), it is pushed down, so that the strip continues to be fed between the guide plates. Repeat the above actions and punch the second part downward.
(2) In a stroke of a continuous punching machine, a die that completes several punching processes at different parts of the die at the same time is called a continuous die. During operation, the locating pin 2 is aligned with the pre-punched locating hole, the upper die moves downwards, the punch 1 punches, and the punch 4 punches. When the upper die returns, the stripper 6 pushes the waste out of the punch. At this time, the blank 7 is conveyed forward again for the second blanking. In this way, each feed distance is controlled by a stop pin.
(3) The compound die is a die that completes several stamping processes at the same time in the same part of the die, which is called compound die. The biggest feature of the compound die is that there is a convex-concave die 1 in the die. The excircle of the punch is the cutting edge of the blanking punch, and the inner hole becomes the drawing die. When the slider moves down with the punch and die, the strip first falls into the punch and die 1 and the blanking die 4. The blanking piece is supported by the drawing punch 2 in the lower die. When the slider continues to move downward, the female die moves downward to draw. In the return stroke of the slider, ejector 5 and ejector 3 push the drawing piece 9 out of the die. The compound die is suitable for stamping parts with large output and high precision.
3, the basic process of stamping The main basic processes of stamping are blanking, punching, bending and stretching.
(1) blanking and punching blanking and punching are the processes of separating blanks.
The process of blanking and punching is exactly the same, but the purpose is different. When blanking, the separated part is the finished product, and the rest is the waste; Punching is to get holes. Punching is the finished product, and the separated part is the waste. Blanking and punching are collectively called blanking. Both the punch and the die of the blanking die have sharp cutting edges, and there is a gap between the punch and the die which is equivalent to 5%- 10% of the thickness of the plate, so as to ensure the neat incision and less burrs.
(2) Bending is to make the workpiece obtain various bending angles. The working part of the bending die for bending the workpiece should have a suitable fillet radius r to avoid the workpiece from breaking when bending.
(3) Drawing: Drawing is the process of making a flat blank into a cup-shaped or box-shaped part. The edges of the punch and die of the drawing die should be round to prevent the workpiece from being pulled apart. A gap slightly larger than the thickness of the sheet metal should be left between the punch and the die (generally 1, 1- 1, twice the thickness of the sheet metal) to reduce friction. In order to prevent wrinkling, the edge of the blank should be pressed by a pressure plate (blank holder). The product will produce tensile crack defects in the actual tensile process. Please see that sheet metal stamping is a working method of separating or deforming sheet metal by using dies. In most cases, the metal plate does not need to be heated, so it is also called cold stamping, also known as cold stamping or stamping.
Commonly used plates are low carbon steel, stainless steel, aluminum, copper and their alloys, which have high plasticity and low deformation resistance and are suitable for cold stamping.
Sheet metal stamping is easy to realize mechanization and automation, and the production efficiency is high; Stamping parts are accurate in size and good in interchangeability; Smooth surface, no need for mechanical processing; Widely used in automobile, electrical appliances, instrumentation and aviation manufacturing.
Structure and working principle of punching machine;
There are many kinds of punching machines, and the commonly used ones are open punching machines. The motor 4 drives the flywheel 9 to rotate through the V-belt 10. When the pedal 12 is depressed, the clutch 8 connects the flywheel and the crankshaft to rotate, and then the slider 1 1 reciprocates up and down along the guide rail 2 through the connecting rod 5 for stamping. When the pedal is released, the clutch is disengaged, and the brake 6 immediately stops the rotation of the crankshaft and stops the slider at the highest position.
Hardware stamping parts are products after a series of processes, and different processes have different names, which is the technical term we often say.
1. Deep drawing: a stamping process that changes a flat blank or process part into a hollow part or further changes the shape and size of the hollow part. In deep drawing, the center piece is mainly formed by the material outside the bottom of the punch flowing into the die.
2. Trimming: Trimming the edge of the molding process with a metal stamping die to make it have a certain diameter, a certain height or a certain shape.
3. Punching: the punching process of separating waste from the material or workpiece along the closed contour to obtain the required hole in the material or workpiece.
Fourth, flanging: a stamping process, which will become a short side along the contour curve.
Fifthly, hole turning: the stamping process of turning the material into a side flange along the periphery of the inner hole.
Sixth, blanking: the stamping process of separating materials along the closed contour. The separated materials become workpieces or machined parts, most of which are planar.
Seventh, shaping: a stamping process that depends on the flow of materials to change the shape and size of the workpiece little by little to ensure the accuracy of the workpiece.