With the continuous improvement of the wage level of workers in the stamping industry, reducing the manual manufacturing cost of stamping has become an urgent task for hardware manufacturers.
Among them, the use of continuous die is the most common.
The use of continuous die can well establish a low-cost and efficient automatic stamping production line.
The continuous die requires precision and complex components.
The problems needing attention in design are more particular than general stamping dies, which are mainly reflected in the following aspects:
(1) When there are many punching holes, the length of small punch should not be too large
For the multi-punch stamping die, the punch with different heights can be made according to the size of the punch to form a stepped die.
It can avoid the maximum punching pressure of each punch at the same time, effectively reduce the punching pressure of the die and reduce the load of the punch.
However, it should be noted that for the stepped punch, in order to ensure sufficient stiffness of the punch, the punch with small size should be made shorter and the punch with large size should be made longer. The difference between the two is the height (sheet thickness).
In this way, punch the large hole first and then the small hole.
Otherwise, the material will squeeze the small punch when punching the large hole, and the small punch will break due to insufficient rigidity.
(2) The continuous die shall be equipped with step positioning devices such as retaining material and side edge as far as possible
When stamping a workpiece with a continuous die, the problem of accurate positioning of the strip must be solved to ensure that the step distance of the continuous die is consistent, so that it is possible to punch a qualified workpiece.
In the continuous die, the commonly used positioning devices include fixed retaining pin, guide pin, guide plate, side edge and so on.
During stamping, the fixed retaining pin shall be used for preliminary positioning, and the guide pin installed in the die shall be used to ensure the correct positioning of the strip during blanking.
The side edge is used to control the feeding distance of strip material in each step.
The length of the side edge shall be equal to the step length plus 0.05-0.5mm, depending on the material thickness.
(3) The guide pin (guide needle) of the continuous die should not be too long
In order to control the feeding step, the continuous die must have a good 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 shut down when used with misdelivery detection sensor to protect the die. Therefore, it is often used in continuous stamping dies.
In high-precision continuous stamping dies, pre punching is often used, and then the guide pin is used to guide the coil in each step.
At this time, the diameter of the guide pin is usually about 1.2 ~ 6mm.
It must be noted that the length of the guide pin shall not be too large, and the length entering the guide hole shall not be too large, otherwise it will cause poor die feeding, belt feeding, etc.
Therefore, the straight body length of the guide pin of the continuous stamping die shall be: the thickness of the guide pin fixed formwork + the thickness of 1 material.
(4) In the continuous die and other automatic stamping dies, it is not suitable to use urethane and polyhelium ester rubber as stripping elements
For the continuous die, a 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 the elastic elements such as urethane and polyurethane are used for unloading, on the one hand, the unloading force may be insufficient and the unloading is unreliable, on the other hand, their service life is also limited.
In order to ensure the reliable and normal operation of the continuous die and reduce maintenance, the spring with strong service life should be used as the unloading element.
(5) The complex or slender shape in the continuous stamping die should not 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 allows, it should be divided into several punches and punched step by step, which can make the die hole easier to process and prolong the service life, facilitate die repair and improve production efficiency.
(6) Empty steps are reserved in the design to facilitate debugging and mold modification
When designing continuous drawing parts or products with unstable forming size, the design of empty station can not be ignored.
For this kind of die, when designing the layout drawing, one or two empty stations are often left after the first drawing and forming, leaving some room for appropriate changes and adjustments after the die test.
For gland parts, there is an empty station between the first drawing and the second drawing.
In addition, when the punch or die orifice is too close, a space shall also be reserved on the layout for the purpose of protecting the structures such as punch, die insert, small die base and cemented carbide insert.
An empty station is reserved between the shaping step and the last blanking step to facilitate the installation of the die and discharge plate and improve the strength of the die.
(7) Anti chip jumping design
The continuous die is a process of continuous stamping of products, especially when there are many punching and trimming.
In order to avoid product crushing and the stability of the die, anti-jump waste structure is usually required in the stamping process.
Mainly from the following points:
- The punch is made into a special shape, which can increase the adhesion of waste on the knife edge;
- Add blowing hole for punch;
- The knife-edge shall be in the form of V-shaped or dovetail clamping;
- Reasonable blanking clearance to reduce skip;
- Waste suction device in the mold.
(8) The carrier of continuous mode cannot be deformed
The workpieces of each process in the continuous die are transferred by the overlapping surplus materials with materials.
The workpieces are generally separated from the belt materials in the final blanking process.
This overlap is called the carrier of continuous modules.
In the continuous die, the common carrier forms are: edge carrier, intermediate carrier, double-sided carrier, single-sided carrier and so on.
The edge material carrier is used to punch the guide hole on the edge residual material of the workpiece, so as to locate the forming processes such as deep drawing and bending.
The carrier has the advantages of simple design, reliability and material saving, so it is widely used.
The middle carrier cuts most of the materials around the workpiece along the strip, leaving only a little connecting material in the middle of the strip width direction. This carrier has poor rigidity and poor continuous stamping stability.
Double-sided carrier is to leave less material on both sides of the belt, and the carrier is rigid and not easy to deform.
It is often used for continuous stamping of thin material and large feed distance workpieces.
One side carrier only leaves a little material on one side with the material.
This carrier has poor rigidity and can only be used for continuous stamping of workpieces with large material thickness and small feed distance.
Because the continuous die has high requirements for step accuracy, in order to ensure the dimensional accuracy of step and improve the working stability of continuous die, the carrier cannot be deformed.
Therefore, the design of the carrier is an important aspect of continuous die design.
In order to ensure that the carrier has sufficient strength and rigidity, it is often used to appropriately increase the lap size;
When the strength of single-sided carrier is insufficient, double-sided carrier and intermediate carrier can be designed;
Punch out the process notch 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 protection
In the design of continuous die, quick disassembly of parts and anti stupidity of parts / standard parts are particularly important.
In order to achieve the purpose of rapid mold repair, the whole set of molds are rarely removed from the machine during continuous mold maintenance, but the components and templates to be repaired are removed separately when they are stopped.
Therefore, the quick disassembly 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 wrong direction of the template, resulting in the damage of the mold. Therefore, we need to pay attention to the anti-stupidity of the parts and templates.
The above is some personal experience in designing molds. If you are interested in stamping molds and have problems in hardware manufacturing, you can leave your comment below.