There has always been a saying in the machine tool industry that machine tools need to release stress, and the more high-precision machine tools are, the more attention should be paid to stress release. So, why do we need to release stress? If so, how long should we release it? How to release stress? Don't worry, and read the article slowly.
▌ What is stress? When an object is deformed due to external factors (force, humidity, temperature field changes, etc.), an internal force that interacts between the parts of the object is generated to resist the effect of this external factor and try to restore the object from the position after deformation to the position before deformation.
The full name of the stress that the machine tool needs to release is mechanical stress, which is generated by components such as the bed during hot forming processing. Since the high-precision machining accuracy of the machine tool needs to reach the micron or even nanometer level, the deformation error caused by the internal stress generated in casting is unacceptable, so the machine tool needs to release stress. Simply put, machine tool related components will generate stress during hot processing. This stress will cause certain deformation of the components, and this deformation will affect the accuracy of the machine tool. Therefore, the more high-precision machine tools are, the more stress needs to be released to ensure the accuracy and stability of the machine tool.
▌ How long does it take for machine tool stress to be released? Machine tool stress is generally released by static method, I believe everyone knows this. I heard that in the past, some machine tool manufacturers would sink castings to the seabed or bury them underground in order to fully release stress. This statement is not testable and is only for your reference. So how long does it take for machine tool stress to be released?
When searching for information online, the various answers are dazzling, ranging from a few months to seven or eight years. There are all kinds of answers. After consulting some professional papers, my answer is that stress release depends on the different metal components, and considering factors such as volume and shape, it takes about several months to several years.
It should be noted that the environment for releasing stress should be considered according to the specific situation of the component. The best effect cannot be achieved outdoors or in some extreme environments. Of course, with the advancement of technology, there are more and more ways to release stress, and the time is getting shorter and shorter.
▌ How to release stress? As mentioned above, static is one of the methods to release stress, but this method is now used less and less. The reason is that static release of stress takes too long and is too costly for machine tool manufacturers. With the advancement of technology, there are more and more ways to release stress in machine tools, and the time is getting shorter and shorter. Before talking about the specific methods of releasing stress, it should be emphasized that stress release is generally completed before assembly. The assembled machine is generally left to stand for about 10 to 20 days after the machine is dropped. It can be done according to the instructions of different manufacturers. Generally speaking, high-precision machine tools will use marble and other materials that are not easy to generate stress as the bed. Machine tools using metal materials now also use shot peening, vibration, rolling and other methods to remove stress. Shot peening uses pellets to bombard the surface of the workpiece and implant residual compressive stress; vibration uses a vibrator to form resonance with the workpiece to eliminate stress; rolling uses some rolling tools to apply pressure to the surface of the workpiece to achieve the purpose of eliminating stress. In addition, stress can also be eliminated by methods such as thermal aging, explosion, thermal shock aging, and sonic aging.
