CNC program precision prototype precision dental parts

Debugging requirements for materials of curved parts。CNC program precision prototype precision dental parts

(1) The materials used for the mold test must meet the requirements of the process card, not only the material grade and grade should be the same, but also the state of the same.

(2) The surface quality of the sheet must be flat, otherwise warping and curling will result in inaccurate positioning and unqualified products.
(3) The dimensions required for compound adjustment of external dimensions, especially the dimensions with tolerance requirements.
(4) For stamping parts that require high cross-sectional quality and surface flatness for medium and heavy plates, the rolling direction of the sheet or coil should be identified.
(5) The material of the first adjustment mold should be consistent with the material used in mass production, including the state of the material (soft state and hard state).
(6) Pay attention to the supply status of raw materials and standardize the management system of raw materials. CNC program precision prototype precision dental parts

Factors and methods that affect the springback of stamping parts during adjustment

    In actual stamping production, springback is an important factor affecting the quality of stamping parts. The cause of springback can be known from the process analysis of bending deformation. When the sheet is plastically bent, it is always accompanied by elastic deformation, so when the bending part is taken out from the mold, the pure elastic deformation near the neutral layer is due to the recovery of the elastic deformation part in the total deformation of the inner and outer regions, making the bending part of the bending part. Both shape and size change in the opposite direction of deformation when loaded, a phenomenon known as springback. The materials, processes, molds and shapes of the parts used for bending and forming are different, and the springback of the parts after forming is also different. CNC program precision prototype precision dental parts

The main factors that affect the rebound are:

   (1) The mechanical properties of the material, the amount of springback is proportional to the yield strength of the material, that is, the greater the yield strength of the material, the greater the amount of springback; the smaller the strain hardening index of the material, the greater the amount of springback .

   (2) The relative bending radius reflects the degree of deformation of the sheet when it is bent. As the degree of bending deformation changes, the proportion of elastic bending deformation in the total bending deformation is constantly changing. When the relative bending radius decreases, the amount of springback decreases accordingly.

   (3) The more complex the shape of the bending part, the greater the mutual restraint effect of the deformation of each part during bending deformation, increasing the deformation resistance during bending, reducing the compression deformation component in the inner area of the sheet, thus reducing the return of bending and forming. Ammo volume.

  (4) The larger the gap between the convex and concave molds of the bending die, the lower the degree of material sticking and the radial constraint on the straight edge of the bending part. The greater the springback of the part.

   (5) There are two ways to bend the sheet metal, the free bending of the bottomless die, and the correction bending of the bottomed die. After the bottomless die is formed, the springback of the part is large, and the bottomed die has a small springback. CNC program precision prototype precision dental parts

Through the analysis of the influencing factors of springback, the measures to reduce and control springback in daily work are as follows:

    1. Reasonable design of products. Select appropriate materials and improve the local structure of parts. Using a material with a large elastic modulus and a low yield strength can reduce springback. For harder materials, annealing before forming can reduce springback. Press suitable reinforcing ribs in the deformation area of the bending part to change the material stress and strain distribution in the deformation area, which can not only increase the rigidity of the part, but also reduce the amount of bending springback.


    2. Compensation Act. When bending at a single corner, according to the estimated springback, the fillet radius and top angle of the punch are made smaller in advance to compensate for the springback; when there is a pressing plate, the springback can be set on the lower die to make the die gap For the minimum material thickness. When the double corners are bent, a springback angle can be made on both sides of the punch or a circular arc can be made at the bottom of the die to compensate for the springback of the corner. CNC program precision prototype precision dental parts


    3. Correction method. The corner of the bending die is made into a protruding shape. When the bending deformation ends, the punch force will concentrate on the bending deformation area, forcing the inner metal to be squeezed, resulting in a tangential elongation strain, thereby reducing the amount of springback. CNC program precision prototype precision dental parts