With the development of economy and the improvement of people's living standards, automobiles have begun to be widely used in people's daily life, which has driven the development of the automobile industry and the improvement of related technologies, and people have put forward higher requirements for the functions and quality of automobiles. . In order to improve the quality and performance of the car, it is necessary to pay attention to the positioning of titanium modified car accessories. The assembly positioning of automobile parts affects the stability and service life of the automobile, and is an important link in the automobile manufacturing process. The positioning principle should be followed when the parts are assembled.
1. The principle of space rectangular coordinates. Auto parts are designed in a three-dimensional space coordinate system. Therefore, as a free rigid body, titanium modified car parts manufacturers move along the X, Y, and Z coordinate axes in the three-dimensional rectangular coordinate system and decompose into translational degrees of freedom. , Rotating around the X, Y, and Z coordinate axes is decomposed into rotational degrees of freedom, that is, any auto part has six degrees of freedom. If the auto parts want to be firmly positioned, they need to cooperate with each other to limit these six freedoms. Degree to achieve the positioning of auto parts. The six-point positioning principle is an important principle in the assembly and positioning of auto parts, that is, points are first used to limit the spatial freedom of parts, followed by lines to limit the spatial freedom of parts, and finally can be considered to be restricted by surfaces. When applying the positioning principle, attention should be paid to the wear and deformation of automobile parts. When using positioning points to limit the parts, there should be no zero distance limit, but a distance of 0.1~0.2 mm should be left. In addition, it is necessary to consider the strength of the parts during assembly and positioning of auto parts, and determine the number of positioning points according to the strength of the parts. Not all parts must be positioned with six positioning points. This is the principle of incomplete positioning and over positioning. Incomplete positioning means that fewer than six restricted points do not affect the function and performance of the parts. Such as the armrest box, glove box and other parts of the car, this positioning method is commonly used. Over-positioning refers to the use of multiple restriction points for positioning in order to enhance the positioning effect, which is suitable for the positioning of large and easily deformed parts. For example, the matching structure of the high-position brake light and the tail wing adopts two parts for Z-direction positioning, and one part for Y-direction positioning, which is to prevent the high-position brake light from deforming and cause uneven positioning of the left and right end points.
2. Reference plane and reference hole design principle The datum is used to determine the point, line or surface on which the geometric relationship of auto parts is based. The datum surface of automobile parts is required to be flat, large, stable in size, and certain deviations are allowed. The accuracy of the datum surface must be able to match the functional and accuracy requirements of the applied parts. For example, the mating surface of the assembly and the gap difference form the facing datum surface The accuracy requirements are different, and the manufacturing process cost is also saved. There are two design schemes for the reference hole, H2S and H2H. The H2S scheme has a round reference hole, which controls 4 directions and restricts two plane degrees of freedom. A long reference hole restricts two orientations and 1 degree of freedom of rotation. H2H has two round reference holes with different position tolerances, which control 4 directions, which is essentially an over-positioning. H2S solutions are often applied to parts with strong rigidity and large dimensional deviations such as internal and external parts such as beams, sheet metal assembly parts, sub-frames, and front skins. H2H is often applied to single thin sheet metal parts such as side wall outer panels and B-pillar inner panels. Both of these programs are designed to reduce the deviation in the production of titanium modified cars.