Materials of T8, T8A, T10, T10A, 42CrMo, Cr12MoV. 42CrMo, Cr12MoV are commonly used for CNC bending machine mold.
The material of the bending machine mold is one of the most important factors affecting the service life. With superior material, the mold's service life will be relatively prolonged in the absence of other variables.
Another important factor affecting service life is the heat treatment process during processing. Firstly, systemic heat treatment is absolutely different from knife oxidation. In order to save processing costs, some press brake die manufacturers proceed oxidation on main parts of the tool edge not have the whole mold heat treated. Which will severely shorten service life.
Secondly, the specific heat treatment process also matters. High temperature furnace heat treatment is commonly used. Although the mold surface can achieve a certain hardness, each part will have a certain difference more or less. High temperature heat treatment can do only on the surface of dies. The more inside, the lower the hardness will be. So what kind of craft is the better heat treatment process?
For the time being, in China, the salt bath furnace heat treatment process is the most suitable.
Reason 1: It can ensure the surface tolerance of each part after heat treatment
Reason 2: It can penetrate into the interior of the tools, making the consistence of even the internal hardness and external hardness of the product, which itself strengthens the overall strength of the mold.
Reason 3: It can control the hardness range of the heat treatment needed in a very small range, while the heat treatment hardness error of high temperature heat treatment is more difficult to control.
If the workpiece has too much burr or abnormal noise during stamping, it may be that the die has been passivated. Check the punch and lower die, when the edge wear produces an arc radius of about 0.10 mm, it will be grinded.
Practice shows that grinding a little often instead of waiting for non-grinding time will not only maintain good workpiece quality, reduce the blanking force, but also prolong the life of the die more than twice.
In addition to knowing when to grind the die, it is particularly important to master the correct grinding method. The grinding rules of the die are as follows:
1. When grinding, the punch is clamped vertically in the V-groove or fixture of the magnetic chuck of the surface grinder. The grinding amount is 0.03-0.05mm each time, and the maximum grinding amount is generally 0.1-0.3 mm until the punch is sharp.
2. Sintered alumina grinding wheel with hardness D~J and abrasive particle size 46~60 is the best choice for grinding high-speed steel.
3. When the grinding force is large or the mould is close to the grinding wheel, adding coolant can prevent the mould from overheating and cracking or annealing. High-quality multi-purpose coolant should be selected according to the manufacturer's requirements.
4. The downward feed of grinding wheel is 0.03-0.08 mm, the transverse feed is 0.13-0.25 mm, and the transverse feed rate is 2.5-3.8 m/min.
5. After grinding, grinding the edge with asphalt to remove burrs and grinding the rounded corners with radius of 0.03-0.05 mm can prevent the edge from cracking.
6. The punch is demagnetized and sprayed with lubricating oil to prevent rusting.