With the continuous improvement of the wage level of stamping industry workers, reducing the labor cost of stamping has become a top priority for hardware manufacturers. And one of them is the most common use of continuous die, which can be used to establish a low-cost and high-efficiency automatic stamping production line. The continuous die requires precision and complex parts. Compared with the general stamping die, the problems that need to be paid attention to in the design are more exquisite, which are mainly shown in the following aspects:
(1) When there are many punching holes, the length of small punch should not be too large
For multi punch stamping die, different punch heights can be made according to the size of the punch to form a stepped type, which can avoid the maximum punch pressure of each punch at the same time, effectively reduce the punch pressure of the die and reduce the load of the punch press. However, it should be noted that for the step punch, in order to ensure that the punch has enough stiffness, the punch with small size should be made shorter, and the punch with large size should be made longer. The height difference between the two is the sheet metal thickness). In this way, large holes are punched first and then small holes are punched. Otherwise, a small punch will be formed when the material extrudes the big hole, and the small punch will be broken due to insufficient rigidity.
(2) As far as possible, the continuous die should be equipped with step distance positioning device such as blocking material and side edge
When stamping workpiece with continuous die, it is necessary to solve the problem of accurate positioning of strip and ensure the consistent step of continuous die, then it is possible to punch qualified parts. In the continuous die, the commonly used positioning devices are fixed stop pin, guide pin, guide plate, side edge and so on. During stamping, the fixed stop pin is used for preliminary positioning, and the guide pin installed in the die is used to ensure the correct positioning of the strip during blanking. The side edge is used to control the feeding distance of each step. The length of side edge should be equal to the step length plus 0.05-0.5mm, depending on the material thickness.
(3) The guide pin of continuous die should not be too long
In order to control the feeding step, the continuous die must have a better positioning device. The commonly used positioning devices include guide pin, initial stop pin, side edge, guide pin, etc. the guide pin is a widely used precision positioning method in continuous die. It can also alarm and stop the machine when used with the error detection sensor to protect the die. Therefore, it is often used in continuous stamping die. In the high precision continuous stamping die, it is often used to punch the pre punch hole, and then use the guide pin to guide the coil in each step. In this case, the diameter of the guide pin is usually ∮ 1.2 ~ 6mm. It must be noted that the length of the guide pin should not be too large, and the length into the guide hole should not be too large, otherwise it will cause the mold feeding is not smooth, with material and so on. Therefore, the straight length of the guide pin of the continuous stamping die should be: the thickness of the guide pin fixed template + the thickness of one material.
(4) It is not suitable to use uniglue or polyurethane rubber as stripper in automatic stamping dies such as continuous die
For the continuous die, which is a kind of high efficiency production die, its service life is often more than 500000-5 million times, and the punching speed is more than 40 times / min. If we use the elastic elements such as uniglue and polyurethane to unload, on the one hand, the unloading force may be insufficient and the unloading is unreliable, on the other hand, their life is limited. In order to ensure the reliable and normal operation of the continuous die and reduce the maintenance, we should generally use the spring with strong life as the unloading element.
(5) The complex or slender shape in the continuous stamping die is not suitable to be punched out at one time
The complex and slender shape in the continuous die should not be punched out at one time. If the process permits, it should be divided into several punches and punched step by step. In this way, the die hole can be processed more easily, the service life can be prolonged, the die repair can be facilitated, and the production efficiency can be improved.
(6) The empty step is reserved in the design, which is convenient for debugging and mold modification
In the design of continuous drawing parts or products with unstable forming size, the design of empty position should not be ignored. For this kind of die, when designing the layout drawing, one or two empty positions are usually left after the first drawing and forming, so as to leave some room for proper change and adjustment after the die test. For the gland part, there is an empty station between the first drawing and the second drawing. In addition, when the hole of punch or die is too close, space should be left on the layout drawing to protect the punch, die insert, small die base, cemented carbide insert and other structures. An empty position is reserved between the shaping step and the last blanking step to facilitate the installation of the die and the discharge plate and improve the strength of the die.
(7) Anti chip design
Continuous die is a process of continuous stamping, especially in the case of more punching and trimming. In order to avoid product crush and the stability of the die, it is usually necessary to make anti jump structure. Mainly from the following points: 1. Punch made of special-shaped, can increase the adhesion of waste on the knife edge; 2. Punch with blowhole; 3. The knife edge should be V-shaped or dovetail; 4. Reasonable blanking clearance to reduce material skipping; 5. In mold waste suction device.
(8) The carrier of continuous die cannot be deformed
In the continuous die, the workpiece in each process is transferred by the lap material of the belt material, and the workpiece is generally separated from the belt material in the final blanking process. This overlap is called the carrier of continuous modules. In the continuous die, the common carrier forms are: Scrap carrier, intermediate carrier, double-sided carrier, single-sided carrier and so on. The blank carrier is used to punch the guide hole on the blank of the workpiece, so as to position and carry out the forming processes such as drawing and bending. The design of this carrier is simple, reliable and material saving, so it is widely used. The middle carrier is along the strip, cutting most of the material around the workpiece, leaving only a little connecting material in the middle of the strip width direction. The rigidity of this carrier is poor, and the continuous stamping stability is not good enough. Double sided carrier is to leave less prying material on both sides of the strip. The carrier is rigid and not easy to deform. It is often used for continuous stamping of thin and large distance workpiece. One side carrier only leaves a little material on one side of the strip, which has poor rigidity and can only be used for continuous stamping of workpieces with larger material thickness and smaller feed distance. Because of the high requirement of the step precision of the continuous die, in order to ensure the dimensional precision of the step and improve the stability of the continuous die, the carrier can not be deformed, so the design of the carrier is an important aspect of the continuous die design. In order to ensure that the carrier has enough strength and rigidity, it is often used to increase the lap size appropriately; When the strength of one side carrier is insufficient, two sides carrier and middle carrier can be designed; The process incision is made between the carrier and the workpiece to separate the carrier from the workpiece, and the deformation of the workpiece will not affect the deformation of the carrier.
(9) Quick disassembly and parts anti dazzle
In the design of continuous die, it is very important to disassemble parts quickly and prevent parts / standard parts from being stuck. Because in order to achieve the purpose of rapid repair, the whole set of mold is rarely removed from the machine when the continuous mold is repaired, but the parts and templates that need to be repaired are removed separately when the machine is shut down, so the rapid removal structure needs to be designed. When the parts and templates are removed and replaced with new parts, it is often easy to install the parts by mistake and make the direction of the template wrong, resulting in the damage of the mold. Therefore, it is necessary to pay attention to the prevention of parts and templates.