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Squeal noise. The torsional noise of a similar press is related to the factors such as the thickness, hardness, geometry, hammering speed, die clearance and other factors of the stamping parts, and the noise increases as these values ​​increase. When the punch press work, the collision impact between the punch and the sheet and the stripper plate and the blank is greatly enhanced. As the impact speed increases, the impact noise also increases, as shown in FIG. The collision noise and the subsequent sound of material fracture can be measured separately. This measurement method has been implemented. In the same punching machine, punching thick and hard material is more noise than punching thin and soft material. For a thick ductile sheet, the impact noise is the same size as the breaking sound. Fig. 1 Effect of impact velocity on sound level 2  punching and shearing noise. The different process noises of the stamping process are very different.
Sheet blanking is more extensive than bending and deep drawing, and the noise in the forming process such as embossing, pressure wave, flanging, bending, and deep drawing is less. The following uses punching as an example to analyze the production of blanking noise. The blanking process can be roughly divided into three stages: elastic deformation, plastic deformation and fracture separation. When punching punches, the punching force begins to increase once the punch contacts the sheet metal. At the same time, elastic energy is accumulated due to deformation of the body and other force members. The punching force reaches a large value when the punch enters about half the thickness of the sheet.
     Sudden rupture of the punch plate causes the punch to suddenly lose its load. The accumulated elastic energy of the fuselage, etc., is released in an extremely short time. It will excite the vibration of the body and various parts and cause shocks between the parts. At the same time, the slider Rushing at a considerable speed causes the pressure of the air around the slider to distort, thereby radiating noise. In addition to the above analysis, the punching noise will increase when the spacing between the punches, including the left and right, front and rear punches, is less than the factory design specification. The density of the installed press is too large and the noise will increase significantly. The net space in the press room should not be too small. The truss lower level below the 4 meters will increase noise, reverberation, and noise.
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