Views:0 Author:Site Editor Publish Time: 2020-05-12 Origin:Site
Classification of sheet metal
1 Classification by geometry
Sheet metal parts can be divided into expandable sheet metal parts and non-expandable sheet metal parts according to whether they can be expanded. Expandable sheet metal parts can be divided into round pipe fittings, polygon pipe fittings, irregular shaped pipe fittings, flat bending pieces, and circular Shaped tube and round tube intersecting parts, round tube and flat tube intersecting parts, plane tube and flat tube intersecting parts, section steel and round tube intersecting parts. Non-expandable parts can be divided into spherical parts, spiral surface parts, etc. The above classification can also be divided in more detail.
2 Classification by plate thickness
(1) Thick sheet metal: We are used to calling the plate structure of 3ram or more as thick sheet metal, which features manual work, and the welding process requirements are extremely high, such as hulls, aircraft carriers, viaducts, and many other products that require welding.
(2) Medium plate sheet metal: We are used to calling the 1-3mm plate structure the medium plate sheet metal. Features: CNC operation, mechanization, and high assembly process requirements, such as switch cabinets, computer chassis and other products.
(3) Sheet metal: We are used to calling the plate structure below 1.2mm as sheet metal, which is characterized by hydraulic mold forming, such as car body and other composite surface products.
3 Classification by part molding
Sheet metal parts can be generally divided into three categories as shown in Table 2.1:
(1) Flat type: refers to the general flat punching and shearing parts, as shown in Figure 2.1.
(2) Bending type: It is a part formed by bending and welding flat sheet materials, as shown in Figure 2.2.
(3) Forming type: It is a kind of part with regular curved surface or free curved surface which is processed by flat sheet material through stretching, indentation and other forming methods. Parts produced by forming processes such as surface die and space shape compressing flat sheets or using professional equipment to stretch flat sheets. These parts will be complicated after drawing, compressing and other related processes. The spatial position relationship, and this is very different from the general machining or casting parts as shown in Figure 2.3. Bending deformation of sheet metal is the main processing feature of forming parts.
In addition, according to the processing methods of sheet metal parts, sheet metal parts can be divided into manual sheet metal, stamping sheet metal and CNC sheet metal. In the current industrial production of sheet metal parts, stamping forming is the mainstream processing method of sheet metal processing, and its processing principle is to use a mold to directly generate a deforming force on the sheet material to obtain a specific shape. The stamping forming process is simple, and the sheet metal parts are reliable and highly accurate.
2.2 Outline features of sheet metal parts
The main features of sheet metal parts can be divided into: shape features, accuracy features, material features, etc., where shape features refer to the geometric entities of sheet metal parts and the spatial positional relationship between various parts. During the processing process, the sheet metal parts The shape feature will directly determine the processing technology of the part and the result of the optimized layout. Therefore, the study of the shape feature plays an important role in the optimal layout of the sheet metal part. According to the geometric characteristics of sheet metal parts, the following characteristics can be summarized:
(1) Plane feature: refers to the geometric feature formed directly on the sheet using processes such as shearing and punching.
(2) Bending feature: refers to the geometric bending feature formed on the sheet using a bending process.
(3) Hole feature: It refers to the regular or irregular hole-like geometric feature that can be produced by punching, drilling, cutting and other technological means on the basis of other contour features. In the production of sheet metal parts, a hole is often used to achieve a certain function, such as punching a positioning hole on a plane, so it is attached to other features as a general sub-feature. The study of holes in the production process of parts is very conducive to the utilization of materials.
(4) Local forming features: refer to the local geometric features formed on sheet or blank by forming processes such as stamping.
Shape features are also called geometric shape features. The process of processing sheet metal into sheet metal parts is usually the process of establishing the correct geometric shape. In this process, it is very important to correctly expand the sheet metal parts according to the geometric shape through effective expansion rules. This step is to establish a reasonable expansion rule for sheet metal parts, which is very beneficial to improve the processing efficiency and the processing accuracy of the parts. It should be noted in the development of sheet metal parts: sheet metal parts are mainly characterized by flat and curved surfaces, and punching and local forming features are described as auxiliary features of the main feature. Each planar feature can be connected to multiple curved features, and each curved feature can only be connected to two planar features at both ends. This paper mainly studies the solutions of the planar features and bending features of sheet metal parts in the layout optimization.