The bending and forming of metal plates are carried out on a bending machine. The workpiece to be formed is placed on the bending machine, the brake shoe is lifted by the lifting rod, the workpiece slides to a proper position, then the brake shoe is lowered onto the workpiece to be formed, and the metal is bent and formed by applying force to the bending rod on the bending machine.
Extended data:
The application range of HRC scale is 20~70HRC. When the hardness value is less than 20HRC, HRB scale should be used instead because the conical part of the indenter is pressed too hard and the sensitivity is reduced.
Although the upper limit of the HRC scale is 70HRC, when the hardness of the sample is greater than 67HRC, the pressure at the tip of the indenter is too high, the diamond is easy to be damaged, and the life of the indenter will be greatly shortened, so HRA scale is generally used instead.
The application range of HRA scale is 20-88HRA, and the following conversion relationship can be obtained from American standard ASTME 140:
27HRA≈30HRB
60HRA≈ 100HRB≈20HRC
85.6HRA≈68HRC
It can be seen that the measuring range of HRA scale covers the hardness range from low carbon steel (HRB) to hard steel (HRC) to cemented carbide. But in fact, HRA ruler is rarely used to test low carbon steel, mainly used to test thin hard steel plate, deep carburized steel and cemented carbide.
In cemented carbide, due to technical progress, the hardness of some materials has reached 93-94HRA, which has exceeded the standard. It has become a common practice to go beyond the high-end measurement range of HRA in engineering.
HRA rulers have special purposes. When testing steel samples with Rockwell hardness tester, if you don't know whether the samples are soft steel or hard steel, you can test them with HRA scale first. When the hardness value is less than 60HRA, HRB scale can be used, and when the hardness value is greater than 60HRA, HRC scale can be used.