Automobile panels

1. Definition of automobile panels

Automobile panels (referred to as panels) refer to the components that cover the engine, chassis, cab and Surface parts and internal parts of the thin steel plate expansion body of the vehicle body.

Compared with general stamping parts, covering parts have the characteristics of thin materials, complex shapes, mostly spatial curved surfaces, large structural dimensions and high surface quality.

2. Classification of automobile covering parts

Covering parts can be divided into three categories according to their functions and requirements: outer covering parts, inner covering parts and frame parts. This book mainly discusses outer coverings and inner coverings.

The outer cover refers to the exposed stamping parts on the outside of the automobile body. The surface quality of the outer covering parts is required to be high, and it is painted directly after welding, and the surface is no longer covered with other decorations.

The inner cover refers to the stamped parts inside the automobile body. It and the outer cover are welded with the skeleton parts to form the body in white. Since the inner covering parts generally cover the interior parts after painting, people cannot directly observe them after the body is formed. Therefore, compared with the outer cover, the surface quality requirements of the inner cover can be relatively lower.

The car cover is mainly composed of 16 panels, 1 top cover and 1 side panel (the definitions of each company are different): left/right front door outer panel, left/right rear door outer panel; left/right front door inner panel Panel, left/right rear door inner panel; front cover outer panel, front cover inner panel; rear cover outer panel, rear cover inner panel; top cover, side panels, left/right front fender, left/right rear fender, etc. . Figure 1-1 shows the composition of car covers.

3. Characteristics of automobile panels

① Stamping parts with large outline dimensions and spatial curved shapes, such as the side panels of some models of domestic cars, their length and dimensions It can reach more than 3000mm and has complex shapes.

② The outer and inner covers are made of 08AL or ST14 materials with thicknesses of 0.75mm, 0.8mm, 0.9mm, 1.0mm, 1.4mm, etc. Foreign ones include 0.60mm, 0.65mm, 0.70 It is stamped from CR4 or JAC340H steel plates such as mm, 0.75mm, 1.2mm, etc. India also uses thin plates with a thickness of 0.67mm and a material code of C23. Nowadays, some car interior covering parts such as left/right front door inner panels, left/right rear door inner panels, etc. are made of two thickness materials (usually 0.8mm and 1.4mm) using laser welding and other processes (or called tailor welding). plate), its purpose is to improve its strength and avoid deformation due to frequent opening and closing of the door.

③Most covering parts generally must go through a drawing process to obtain them.

④ The deformation process of materials during stamping is complex, and professional software, such as AutoForm, must be used to analyze and simulate whether local quality defects such as cracking may occur during the drawing deformation process.

⑤Equipment (such as three-dimensional coordinate measuring instrument, etc.) and special measuring and inspection tools must be used to evaluate whether the size and shape are qualified.

⑥The tonnage of stamping equipment used for processing is generally relatively large, and the largest press can reach more than 2,400t.

Surface quality requirements for automobile panels

Automobile panels require smooth surfaces and clear edges. Wrinkles, indentations, scratches, burrs, bumps and depressions are not allowed. and other quality defects that undermine surface perfection.

Definition of defect: A defect is a deviation obtained by comparing the quality target with the actual quality.

At the same time, the surface of the relevant covering parts must also have good coordination, uniform transition, and smooth ridge joints, so that the car body looks coordinated and beautiful in appearance. Therefore, only through careful analysis, judgment and research on surface quality defects can corresponding rectification measures be formulated.

Before judging surface quality defects, you must first understand the division of automobile panel inspection areas. These divisions are suitable for parts such as paint and sheet metal.

As shown in Figure 1-2, the automobile panel inspection area can be divided into four areas, namely areas I, II, III and IV. The specific parts included in the four areas are shown in Table 1-1.

Table 1-1 Parts included in the four areas

The evaluation of surface defects of automobile panels is shown in Table 1-2.

Table 1-2 Reference for evaluation of surface defects of covering parts

Any covering parts shall not have Class A defects, missing punching holes, rust, etc., which are not allowed in Zones I and II. There are obvious oil patterns.

Table 1-3 lists the areas where surface defects of the covering are not allowed to exist.

Table 1-3 Areas where surface defects of covering parts are not allowed to exist

① Repair welding is required, but the repaired parts are not easily noticeable and do not affect the function of the entire vehicle. ②Individual pitting is acceptable if the spacing is more than 300mm, but no more than 2 points are allowed on one continuous surface.