1. Determine the deformation compensation according to the material and product structure.

2. According to the compensation amount, design the die to punch out the finished product or semi-finished product.

3. Processing the semi-finished products into finished products.

4. Bad phenomena include cracks, wrinkling, strain, uneven thickness and no molding.

Tapping and threading:

1. First drill the diameter and depth of the bottom hole of the internal thread (the size of the bottom hole is determined according to the thread specification); The external thread is machined to the size of the external circle to the large diameter of the thread (the size is determined according to the thread specification).

2. Machining threads: tapping internal threads with taps of corresponding grades; External threads can be turned with thread cutters or covered with threads.

3. Bad phenomena include thread, inconsistent size and unqualified thread gauge inspection.

Attachment: According to the use requirements, the materials are mainly metals or nonmetals with low deformation resistance, good plasticity and good ductility, such as copper, aluminum and low carbon steel.

Stamping is a kind of forming processing method to apply external force to plates, strips, pipes and profiles by means of presses and dies, so that they can be plastically deformed or separated, thus obtaining workpieces (stamping parts) with required shapes and sizes. Stamping and forging belong to plastic processing (or pressure processing) and are collectively called forging. Stamping blanks are mainly hot-rolled and cold-rolled steel plates and strips.

Stamping parts are mainly formed by stamping metal or nonmetal plates with the help of the pressure of a press. It mainly has the following characteristics:

(1) Stamping parts are stamped on the premise of low material consumption. Parts are light in weight and good in rigidity. After plastic deformation of metal plate, the internal structure of metal is improved and the strength of stamping parts is improved.

⑵ The stamping parts have high dimensional accuracy, uniform dimensions of the same module and good interchangeability. General assembly and use requirements can be met without further processing.

(3) In the stamping process, the surface of stamping parts is not damaged, so it has good surface quality and smooth and beautiful appearance, which provides convenient conditions for surface treatment such as painting, electroplating and phosphating.

Stamping part is a production technology that with the help of the power of conventional or special stamping equipment, the plate is directly deformed by deformation force in the die, so as to obtain product parts with certain shape, size and performance. Sheet metal, die and equipment are the three elements of stamping. Stamping is a cold deformation processing method of metal. Therefore, it is called cold stamping or sheet metal stamping for short. It is one of the main methods of metal plastic working (or pressure working) and also belongs to material forming engineering technology.

In the world, 50 ~ 60% of steel products are plates, and most of them are finished products after stamping. Automobile body, radiator, steam boiler drum, container shell, iron core silicon steel sheet of motor and electrical appliance, etc. They are all stamped and processed. Instruments, household appliances, office machines, storage utensils and other products, there are also a large number of stamping parts. Stamping is an effective measure. Using compound die, abnormal is multi-station progressive die, which can complete multiple stamping operations on one press and complete the automatic generation of materials. The production speed is fast, the rest time is long, the cost is low, and the collective can produce hundreds of pieces per minute, which is loved by many processing plants.

Stamping parts are thin, uniform, light and have strong fighting power with castings and forgings. Stamping can be used to produce workpieces with stiffeners, ribs, coils or flanges that are difficult to manufacture, so as to improve their rigidity. Because the rough die is eliminated, the precision of the workpiece can reach micron level, the precision is high and the specifications are consistent, and holes and bosses can be punched. In actual production, process tests similar to stamping process, such as drawing performance test and bulging performance test, are often used to check the stamping performance of materials to ensure the quality of finished products and high qualified rate.

In addition to forming thick plates with hydraulic press, the stamping equipment usually adopts stagnation press. Focusing on the modern high-speed multi-station stagnation press, the passive stamping line with high mortality rate can be formed by setting up equipment configurations such as uncoiling, finished product collection, walking stagnation, die set library, rapid die change and adopting computer French tube bundle. When there are dozens or hundreds of stamping parts per minute, personnel, equipment and quality accidents often occur when stamping and discharging processes are completed in a short time. Therefore, the safety of stamping is a very important topic.

1. Causes of overturning and deformation in stamping process

In the progressive die, the shape of stamping parts is formed by stamping the residual materials around the stamping parts. The main reason for the turnover and deformation of stamping parts is the influence of blanking force. During blanking, due to the existence of blanking gap, the material is stretched on the side of the female die (material warps upward) and compressed on the side close to the male die. When the stripper is used, the material is pressed by the stripper to prevent the material on the female die side from warping upwards, and the stress state of the material also changes accordingly. With the increase of the pressing force of the stripper, the material near the punch is stretched (the compressive force tends to decrease), while the material on the die surface is compressed (the tensile force tends to decrease). The turnover of stamping parts is caused by the stretching of die surface materials. Therefore, when stamping, pressing and compacting is the key point to prevent the stamping parts from turning over and twisting.

2. The method of restraining the turnover deformation of stamping parts.

(1). Reasonable mold design. In progressive die, the arrangement of blanking sequence will affect the forming accuracy of stamping parts. In order to reduce the influence of blanking force on stamping parts, large-area blanking is usually arranged first, and then small-area blanking is arranged.

(2). Press the material. The traditional mold design structure is overcome, and a material holding gap is opened on the stripper plate (that is, the stripper plate is attached to the female die when the mold is closed, and the gap between the stripper plate and the female die holding the material is t-0.03 ~ 0.05 mm). In this way, the discharging plate moves smoothly during stamping and the material can be compacted. In the key molding position, the discharge plate must be made into an insert structure to solve the wear (pressure) loss caused by long-term stamping at the pressing position of the discharge plate, and the material cannot be pressed.

(3). Increase the strong pressure function. That is, the pressing part of the discharge insert is thickened (the normal thickness of the discharge insert is H+0.03mm) to increase the pressure on the side material of the die, so as to prevent the stamping parts from turning over and twisting during stamping.

(4) The end of the cutting edge of the punch is trimmed with an inclined plane or an arc. This is an effective way to slow down the blanking force. By slowing down the blanking force, the tension on the side material of the die can be reduced, so as to achieve the effect of restraining the turnover and distortion of stamping parts.

(5) In the daily mold production, attention should be paid to maintaining the sharpness of the cutting edges of the punch and the die. When the stamping edge is worn, the tensile stress of the material will increase, so the tendency of overturning and twisting of stamping parts will increase.

(6) Unreasonable or uneven blanking gap is also the cause of turnover and deformation of stamping parts, which needs to be overcome.

3. Handling of common specific problems in production

In daily production, we will encounter the situation that the punching size is too large or too small (which may exceed the specification requirements), and the size is quite different from that of the punch. In addition to considering the design size, machining accuracy and blanking gap of forming punch and die, the following aspects should be considered to solve it.

(1). When the cutting edge is worn, the tensile stress of the material increases, and the tendency of stamping parts to turn over and deform increases. When the material is turned over, the punching size will become smaller.

(2) Strong pressure on the material will cause plastic deformation of the material, which will lead to larger stamping size. When the strong pressure decreases, the stamping size will become smaller.

(3) The shape of the cutting edge end of the punch. If the end is trimmed with inclined plane or arc, the stamping size will become larger, because the stamping force is slow and the stamping part is not easy to turn over and twist. However, when the punch end is flat (without bevel or arc), the stamping size will be relatively small.

In the specific production practice, we should analyze the specific problems in order to find out the solutions to the problems.

The above mainly introduces the causes and solutions of turnover and deformation of stamping parts during blanking.