Metal Stamping Die
The advantage of metal stamping die is to ensure the dimensional accuracy of stamped parts, with the same characteristics, thus ensuring stable product quality and good interchangeability. This technology can manufacture parts with light weight, good rigidity, high surface quality, and complex shapes.
Automotive Stamping Dies Fundamentals
The materials of automotive stamping dies play a significant role in ensuring the performance and service life of the dies. Stamping die has the characteristics of durability and corrosion resistance, as well as producing workpieces with high precision and surface smoothness. The automotive industry heavily relies on metal stamping die to produce many components, each of which must meet strict standards.
Punching and Debugging of Automotive Stamping Dies
1.Debugging of Stamping Mold Structure
The most effective way to design a reasonable structure for custom stamping dies and improve the accuracy of stamping parts is to improve the technology, production, and assembly adjustment of the custom stamping dies.
1.The punching tool should have a good guiding device, and the gap between the convex and concave dies of the custom stamping tool is not large. There must be a good guiding device to increase the accuracy before introduction, so there is a difference between punching, drawing, and forming dies. For high-speed punching, seamless and precision punching, or hard alloy punching, a steel ball rolling guide column structure with a floating tool handle is generally used.
2.There are many types of positioning devices for automotive stamping dies, and it is necessary to choose the appropriate positioning device and what type of positioning device to use. According to the precision requirements of the product, the combination form of the mold, the mold structure, as well as the actual production conditions and habits. Positioning pins are often used for material cutting or punching, and for the trimming of large thin sheet panels after forming, the formed shape positioning is often used. There are also positioning pins for holes punched during deep drawing.
3.There are deviations in the manufacturing of convex dies, concave dies, and convex and concave dies, as well as the flatness, verticality, and positional accuracy of the cutting edge. The sharpness of the cutting edge during grinding, as well as the fit of the upper and lower surfaces of the cutting edge, can improve the machining accuracy of the working parts of the custom stamping tool.
4.The blade shape of the convex and concave dies should meet the correct standards and reduce the punching force, such as the wavy blade. For a large number of punches, step punching can be used to divide the height of the punch into height differences.
5.The assembly accuracy of stamping dies plays a crucial role, such as the relative positional accuracy between the convex and concave dies, and the verticality and coaxiality of the assembly of the fixed plate between the convex and concave dies. If the assembly accuracy is improper or there is deviation, it can lead to uneven punching clearance and blade damage.
6.Ensure the overall structure of the automotive stamping tool with good rigidity. The supporting and fixing parts of the mold must have good stiffness, otherwise dynamic clearance changes such as movement or tilting may occur during the punching process, causing damage to the mold.
7.The pressing device of the mold can constrain the material near the cutting edge of the blank during punching, while the rest of the material is not subjected to force, preventing deformation of the workpiece. The presence or absence of a material pressing device has a significant impact on the quality of the workpiece. The dimensional accuracy, cross-sectional quality, and surface smoothness of the workpiece with a material-pressing device will be significantly improved.
2.Debugging Method for Punching Clearance of Automotive Stamping Dies
One of the most important factors affecting the quality of punched parts in actual production is the punching gap in the production, adjustment, and repair of dies. The single-sided gap value that meets the standard is 5% to 10% of the thickness of the raw material.
1.The manufacturing clearance, manufacturing clearance, adjustment clearance, maintenance clearance, and manufacturing deviation of convex and concave dies have increased. The minimum reasonable clearance value should be taken for newly manufactured dies.
2.The punching clearance is related to the type of stamping material, supply status, material size, production environment, and equipment used.
3.The adjustment of automotive stamping dies is related to the process requirements, cross-sectional quality, precise shape, workpiece structure, mold usage time, and workpiece quality of the stamped parts.
4.The design of the punching clearance is based on the limit deviation of the center distance of the punching hole, the tolerance of the outer and inner hole dimensions of the punching part, and the reference formulation of the limit deviation of the outer contour deviation of the hole for ordinary and advanced punching dies.
5.Applicable occasions for punching clearance：When the cross-sectional quality and dimensional accuracy of the cut parts are required to be high, small gaps are used, but the punching force is large and the service life of the punching tool is low. When the quality and size of the punching section meet general requirements, a medium gap is used. Due to the small residual stress, it can reduce the phenomenon of cracking and is suitable for workpieces that continue to undergo plastic deformation. To improve the service time of the mold, large gaps will be used in situations where the quality and dimensional accuracy of the punched section are not high because the punching force is small.
Reasons and Measures for Defects in Bending Stamping Dies
If the bending radius is too small, cracking may occur. It often occurs relative to the workpiece, and the low elongation of the sheet metal can also cause cracking. If encountering this problem, the main solution is to use high-grade and high-performance materials, and appropriately increase the radius of convex and concave mold corners. The progressive bending process is generally used for parts with large thicknesses and strict control of bending angle. The problems of deviation and warping can be solved by improving the mold structure. To limit the movement of the parts in the mold, technicians add reverse side, positioning, and side plates. Many methods can be used for rebound, such as bending, correction, and compensation. Under the premise of selecting the method, materials that meet the requirements should be selected.
The precautions and measures in the production of automotive stamping dies include the following:
Adjust the shape, position, and positioning pins of the bending stamping tool. The shape of the external positioning should not deviate from the shape of the parts, and the pin positioning hole must be tightened. Generally, the pinhole is 0.05 millimeters. The height of the positioning surface should be about 3 millimeters greater than the thickness of the material, and the front shape must be made into an inclined or spherical surface, to ensure consistent height of the curved parts, and to fully ensure the reliability and stability of the workpiece positioning and production. If there is a deviation or inaccurate positioning in the position, the technical personnel should adjust the relevant positioning position promptly, and the positioning pin can also be replaced.
The force should be uniform and stable to avoid abnormal noise. The surface of the manufactured components should be flat, without scratches, and should not undergo shape changes or bending. In manufacturing, the pre-pressing amount of the bending tool, the spring of the rubber and discharge parts, the pressure of the return parts, rubber, and air cushion should be flexible, and the parts will be retracted according to requirements to avoid adverse phenomena such as hysteresis.
Install the automotive stamping dies on the equipment that meets the technical requirements. Before pre-installing the machine, adjust the pressure machine to be within 10 millimeters higher than the total height of the mold but greater than 5 millimeters. The size of the driving and supporting rods may vary. Choose the appropriate size according to the corresponding structure and correctly install it in the support rod hole of the workbench. Slightly adjust the slider on the machine to the upper plane of the mold. If there is a support rod, it can be adjusted to within 5 millimeters but greater than 2 millimeters. Use an air cushion and fill it with air. The air pressure should not be too high, and the cushion will rise. If it rises to the upper surface of the mold without any gap, adjust the slider to the bottom dead center, and then clamp it with screws or cylinders.
Adjustment of the height of the bending stamping tool. When there is a limiter for the gap between the convex and concave dies, adjust it according to the limiter. Otherwise, adjust the height based on experience or place the matchstick on the mold surface. Alternatively, use old parts to adjust it to the bottom dead center to prevent jamming, excessive biting, machine failure, and blockage. When there is an observation hole, the contact between the pressure ring, ejector, balance block, and the bottom surface can be observed before adjustment.
Structure of Automotive Stamping and Bending Parts
There are many shapes of bent parts, such as simple V-shaped, U-shaped, L-shaped, and Z-shaped bent parts, which are mostly bent in one go. The bandage pressing device is used in automotive stamping dies to avoid dimensional errors caused by multiple positioning and operation errors.
When the relative radius of the bent part is less than or close to the bending fracture limit, and the dimensional accuracy of the bent part is required to be high, there are special requirements for the surface shape flatness. After completing the bending technology, the shaping step is carried out. Manufacturing small bending stamping dies can adopt composite stamping dies of punching and bending, and continuous processing can be carried out to increase production efficiency.
When using bending technology, defective components such as skewed, rotated, angle out of tolerance, offset, and sliding parts should be designed as reliable bidirectional positioning devices for bending automotive stamping dies. Manufacturers should design pre-clamping structures, and pre-tighten and release the positioning after the convex and concave dies come into contact during operation, otherwise waste and defective products may occur.
For single-piece single-sided flanged parts, if the lateral force is too large, double stations are generally used because they can simultaneously produce double groove dies for symmetrical bending.
For workpieces that need to be bent multiple times, the outer side should be bent first and then the inner side, and there should be no occurrence of shape defects, deformation, or large dimensions.
For parts with slender bends and large opening sizes that are prone to spring back, an adjustable bending die structure is adopted. The convex and concave tool shapes of the automotive stamping bending dies are designed according to the requirements, and the slope of the compensation angle and spring back angle are increased to compensate for the size data specified in the process.
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