Design process of automobile inspection tools

Author：Web　Source：Web　Date：2018-05-26 17:08:51　Sentiment：68

Detailed planning and modeling of workpiece and inspection -- automobile inspection tools

First of all, it is necessary to analyze the workpiece by referring to the part drawings, start to draw up the inspection plan, determine the status of the inspection tool's base surface, concave and convex conditions, detect the section and positioning surface, etc., and make its two-dimensional sketch.

In the planning of automobile inspection tools, the detailed planning and modeling of inspection is the key, which directly affects whether the inspection tools can accurately detect the quality of workpieces.

Because the body covers the surface of the main characteristics of the body surface, "everything in reverse" is now a common method of modeling. Antithesis is the method of using laser scanner to collect data according to existing workpiece or object prototype, and through data processing, 3d reconstruction and other processes, the prototyping model with detailed shape structure is adopted. We use laser scanner to scan the normalized workpiece surface, collect the external feature information of the workpiece with point cloud as the main part, convert the point coordinates to the body coordinates, process the point letter with surfacer software, get the characteristic curve of the workpiece surface surface surface, and then generate the final free surface model. The resulting prototype can be detected through the maximum and minimum spacing between the point cloud and the surface. It should be noted that the model obtained at this moment is a thin-film model without thickness. It is particularly important to distinguish the model as the inner or outer surface of the workpiece according to the scanning appearance of the scanner.

End fixture on workpiece surface testing, generally have made detailed looks and artifacts they keep constant gap 3 or 5 mm, numerical control machine tool in accordance with the planning type surface da reached a relatively high precision requirements, through practical test fixture type surface cooperation measuring tool for reciprocating movement to measurement error of the work piece surface. There are mainly two methods for the inspection of the outer generalizations of the workpiece. When the corresponding inspection tools are designed, the detailed appearance of the outer generalizations of the workpiece extends about 20mm outward. In the direction of the outward summarization of the work piece, circulatory extends down about 20mm. In general CAD software (UG), the workpiece surface inward offset3 or 5 mm intervals (if the generated artifacts model for the outer appearance, for offset plus the thickness of the workpiece), then generalize the surface along the tangential or normal extension of 20 mm, get detailed detection appearance, tensile must interval is checked to datum model in detail. Due to the relatively messy body coverings, the combination of the above two methods is mostly required in the generation of detailed inspection of the appearance, which is still difficult to complete for some special types of surface. Figure 2 shows a schematic diagram of the messy surface. Diagram engine bearing appearance of workpiece in 1, 2 from the intersection of two significant attack and shaft; its flowerlike, in order to get the test to ensure the workpiece mainly summarized, with straight height difference is dedicated to the corner detection, generated as shown in the detailed appearance inspection, finally along the workpiece in detailed appearance inspection summary and interval of 3 mm double line, so as to facilitate test artifacts. Of course, there are many similar problems in the planning of the inspection tools (especially the detailed inspection), all of which require post-processing of the penetration understanding and experience of the inspection principles.

2. Planning and modeling of sectional samples

The inspection of workpiece key shape face is finished through section sample commonly, the section sample of inspection tool is divided into two kinds of rotary type and thrust type, when the span of section sample exceeds 300mm, in order to ensure the detection precision of straight direction, it is planned for thrust type commonly. The inspection detailed exterior detects is the inside exterior of the workpiece, cross section model crosses on the outside surface of the workpiece, use to detect the exterior appearance of key section, its operation exterior space is workpiece exterior 2-3mm commonly, its modelling method is similar with the appearance of inspection tool. The sheet material of section sample is steel or aluminum, the working surface can be made of aluminum or resin. The cross-section sample of the disordered surface will become dry when it is rotated or punctured, which can be segmented in practice planning, as shown in FIG. 3.

If it is set as a puncture cross section sample, it will be connected with the positioning pin of the workpiece. If set to a single rotary type, because the workpiece itself is polyhedral, resulting in detailed inspection or workpiece outbreak of interference, it can be planned into two independent rotary cross section samples to meet the requirements of comprehensive detection.

3. Positioning and clamping of workpiece -- automobile inspection tools

The correct and reasonable positioning of workpiece is the root of accurate measurement. The positioning method of the body cover parts on the inspection tool is mainly completed by the positioning hole and clamping head or the permanent magnet clamping cooperation. Following the extensive application of inspection tools in body making, lever movable chuck and permanent magnet have been selected for serialized products. The movable chuck is also equipped with different types and sizes of bracket or bracket. Most of the body cover parts have two positioning holes, the main one is cylinder pin (round hole) or diamond pin (waist hole), to constrain the comfort of both sides of x. Y. The auxiliary locating pin is a cone pin or diamond shaped plug pin to constrain the comfort of Z.X.Y.Z. When planning inspection tools, punch holes in the orientation of the positioning hole in the inspection details (subject to putting the positioning pin bushing), and give the body coordinates of the positioning hole. With the workpiece has good rigidity and reasonable distribution of bearing placed chuck positioning gaskets and activity, to ensure that the workpiece strong orientation when planning to cut clamping point number, to ensure that activities chuck operations don't meddle with other parts attack, and considering the operation is convenient, the workers will give positioning gasket appearance body coordinates of the center.

4. Floor assembly planning

In the inspection details, the outer surface stretches a certain interval along the direction of the datum surface, making its lowest point greater than 150mm thickness, so as to ensure that the inspection details have a satisfactory intensity. Together, the inspection details of the bottom surface, i.e. the upper surface of the bottom assembly (the base surface), are in the integral direction of the body coordinate system. The inspection detailed floor assembly is generally composed of base plate, channel steel (with i-steel in the center if necessary), positioning block and universal wheel. When the base plate is fixed in inspection detail, other parts can choose the standard type according to the practical situation.

5 hole detection

Many important holes, flanges and other requirements are independently detected in body stamping parts. In the planning of inspection tools, a convex platform with a thickness of about 1mm is added on the surface of inspection details. The center of the convex platform and the hole center of the workpiece are on the same axis, with a diameter of 5mm larger than the hole diameter

When the precision of the hole under test is high, the method of locating hole is used to detect with plug gauge and bushing. Big cover element in the body, because this type of fixture the shape of the mixed and disorderly, huge volume, making higher capital, detection of objects of a single, flexible, difficult to quickly get a lot of precise information, has gradually been advanced automated testing methods (such as online detection system) replaced, but about mass production of small stamping parts inspection, now produce car manufacturers in China is still mainly rely on this type of fixture.