Method for manufacturing parts by incremental forming of sheet billets

Abstract

FIELD: metal forming.SUBSTANCE: the invention can be used in the manufacture of parts by incremental forming of sheet blanks. Manufacturing includes two stages. At the first stage, a sheet blank is preliminary deformed. This ensures deformation hardening of the blank and gives it a conical or spherical shape. At the second stage, the contour of the part is formed.EFFECT: increasing the geometric accuracy of parts by reducing elastic springback.1 cl, 3 dwg

Description

[0001] The invention relates to the field of metal pressure processing and can be used in incremental forming of sheet blanks.

[0002] During incremental forming (Figure 1), the punch acts on the sheet metal, causing localized plastic deformations that accumulate with each pass of the punch across the sheet metal, forming the finished product. However, during the forming process, the sheet metal deforms not only plastically but also elastically, resulting in elastic springback throughout the process, which reduces the geometric accuracy of the resulting part.

[0003] To solve this problem, various methods are used to improve the geometric accuracy of the part during incremental forming. For example, a method of incremental forming using an elastic medium is known (patent WO 2020227224 published on November 12, 2020). According to this method, a matrix made of an elastic medium is installed on the back of the sheet blank, which acts as a support, increases rigidity, and reduces elastic springback during the forming process. A similar method (patent CN 212792651 published on March 26, 2021) forms the sheet using an additional tool in the form of a counter-punch, which, similar to the previous method, is installed on the back of the sheet blank and acts as a stop, moving along a trajectory coordinated with the movement of the main punch and providing additional rigidity to the workpiece during the forming process.

[0004] To improve the geometric accuracy of a part during incremental forming, a method for locally heating a sheet metal blank is known (patent WO 2006110962, published March 19, 2008). In this method, a heating element is installed on the back of the sheet metal blank opposite the punch and moves synchronously with it during the forming process, providing localized heating of the sheet metal in the punch's impact zone. This helps increase the accuracy of the part by reducing the resistance of the sheet metal material to plastic deformation.

[0005] Also known is a method for increasing the accuracy of an industrial robot during incremental forming by using a laser tracking system (patent RU 2762693 C1 published November 15, 2019). In this method, a laser tracker is mounted on the forming tool and monitors its movement and deviations from the specified trajectory. Then, via a communication system and controller, the signal is transmitted to the operator's computer, where specialized software adjusts the punch's trajectory in real time, thereby improving the geometric accuracy of the part.

[0006] All of these patents include the use of additional tools, heating elements, laser or optical tracking systems, the use of which significantly complicates and increases the cost of manufacturing products using incremental forming.

[0007] Similar in technical essence to the claimed invention is a method for shaping parts (Patent No. 2475322, published February 20, 2013). Its essence lies in shaping the part in two stages. In the first, the workpiece is shaped approximately to the final contour, and in the second, the final shape is achieved by loading and heating to the shaping temperature and holding it at this temperature in a fixed state to allow for stress relaxation and aging of the material.

[0008] The proposed method does not require the use of additional equipment or structural elements. Part shaping occurs in two stages. In the first stage, the sheet metal blank is pre-deformed by passing a deforming tool along a specified initial trajectory. The profile of the part after pre-deformation can be conical or spherical and is selected depending on the geometry of the final part (Figure 2). In this first stage, it is necessary to ensure the workpiece is deformed with a minimum degree of deformation, ensuring the transition from an elastic to a plastic state, taking into account the heterogeneity of the workpiece's properties and thickness, as well as uneven loading. The recommended degree of plastic deformation is 2-3% of the workpiece thickness.

[0009] If uniform deformation and minimal thickness variation are required during the first stage of deformation, a conical profile is recommended. If higher rigidity is required for the second stage of forming and uniform deformation and thickness variation are less important, a spherical profile is recommended as the preload profile.

[0010] The second stage begins with a pre-deformed sheet (Figure 3). During this second stage, the basic contour of the part is formed.

[0011] When implementing the proposed method, the sheet metal blank is pre-stressed during the first stage of forming and acquires a shape with greater rigidity, which reduces the springback during the second stage of forming the main contour of the part. Furthermore, forming the part in two stages leads to a redistribution of residual stresses and deformations, localizing them in the pre-stressed sheet, which reduces the springback of the main contour of the part.

[0012] When using the proposed method, elastic springback is reduced due to preliminary deformation of the sheet, which leads to a significant increase in the geometric accuracy of the part during the incremental forming process.

Claims

A method for manufacturing parts by incremental forming of sheet blanks, which is carried out in two stages, wherein at the first stage preliminary deformation of the sheet blank is carried out, and at the second stage the contour of the part is formed, characterized in that the preliminary deformation of the sheet blank is carried out ensuring its strain hardening and imparting a conical or spherical shape.

Images