The structural characteristics of automobile cover parts
1. Large size. The automobile is a large industrial product among the consumer goods. The car cover is the parts that cover the engine and chassis to form the car body. Therefore, the size of the structure size, depending on the size of the car body segments. From the perspective of the function of the cover itself, the larger the block should be, the better. From the body of the overall manufacturing technology Angle analysis, should also be the bigger the better. Therefore, the size of the cover structure is generally larger.
2. sheet thin. In order to reduce the dead weight of the car, the panel selected for the cover is relatively thin. Thickness is a relative concept. The ratio of the girth of the covering (m) and the thickness of the sheet used (mm) is generally above 1.00. The thickness of the cover is generally between 0.6 mm and 1.2 mm.
3. Complex shape. In order to meet the needs of function and beauty, the automobile cover parts are generally composed of three dimensional regular surface and irregular surface composite surface.
4. Express by model. It is very difficult to express the shape and size of automobile panel completely by mechanical drawing because the panel is composed of three-dimensional surface. It’s usually expressed as a model. The model representing the shape and size of automobile panels is called the master model (physical master model and mathematical master model).
Automobile cover parts quality characteristics
1. High dimensional accuracy. When it’s contiguous, it’s a surface. When the transition, natural smooth. After the overlapping of the covering member and the covering member, the two overlapping surfaces are one surface, and there is no gap between them. A soldered body should be a work of art for people to enjoy.
2 the surface quality is strict. The car panel directly reflects the appearance quality of the car. In addition to the high surface roughness requirements, but also requires the cover on the edges and lines clear, smooth smooth, symmetrical, uniform transition, smooth connection, smooth surface transition. No corrugations, wrinkles, indentations, pull marks, abrasions, bumps and other defects that can destroy the perfect surface are allowed on the surface.
3. Strong structure rigidity. Whether it is the cab of a truck or the body of a passenger car, the covering parts that constitute them should be sufficiently rigid. In particular, beamless body parts are stronger and more rigid. Rigidity is insufficient, not only will cause the deformation of the whole body, but also will make the noise of the car moving.
4. good processing technology. Good manufacturability mainly refers to the feasibility of a stamping forming. The manufacturing process of automobile panel is complicated. The panel die is quite expensive. Good stamping process not only can make stamping process simplified, but also can greatly reduce the capital investment of stamping die manufacturing.
Automobile cover parts technological characteristics
1. The establishment of stamping process mainly depends on practical experience and data accumulation. Due to the influence of some uncontrollable factors in the stamping process of automobile panel, it is not possible to use the plastic deformation theory to guide the stamping process design. The application conditions of theory are severe. The present plastic deformation demonstration and analysis software can only play a role in verifying the process. The stamping process of automobile cover parts mainly depends on the long-term accumulated production experience and accumulated data.
2. The stamping process is mostly composite process. Because of the large size and complex shape of the cover, it is difficult to locate and move. Therefore, the use of composite die, and rarely use progressive die. For long and narrow parts sometimes using multi-station die or joint installation is not used progressive die.
3. The basic process of punching covers is forming process, trimming punching process and flanging and shaping process. Forming process is the key process. In order to obtain sufficient plastic denaturation of the covering parts, so as to improve the rigidity of the covering parts, the forming process is generally used in drawing process, rather than pressing process.
4. Use a press with a large working surface and relatively small nominal pressure. The press requirements for pressing automobile covering parts are generally large working table to adapt to the characteristics of relatively large structure size. The effective tonnage of the press is not very large because the panel is thin and the deformation force is small. The precision of the press is also due to the selection of thin plate covering parts, small mold clearance and the accuracy of the cover parts themselves, the requirements are also higher. The most commonly used side four point mechanical press.
Design features of auto panel die
1. Large structure size. In addition to the cover itself is relatively large, the positioning of the parts of the cover die, the installation structure of the die, the guidance of the upper and lower die, the lifting, flipping and transportation device of the die are to increase the structural size of the die.
2. The base part is the frame structure. The structural size of the die for automobile cover parts is large. In order to reduce the weight of the die and improve the manufacturing process, the general design is composed of two slabs of horizontal two layers, the middle of the frame structure connected with vertical bars. The basic parts of the general punching die (die seat) more for the selection of standardized solid plate.
3. Low degree of standardization. The general degree of standardization of die design and the selection of standard parts than the coverage of the die is much larger. For example, the general punching die can be all selected from standard parts assembly, and the automobile cover die at least its basic parts are not the target.
4. The mould material quality requirement is relatively low. For the working parts (punch, die, blank holder) of the covering drawing die with a life of 400,000 times or less, the cast iron with a higher strength is generally used. The working parts of the general die are mostly tool steel.
Automobile cover parts die manufacturing characteristics
1. The preparation of the blank of the basic parts and working parts of the stamping die of automobile covering parts is the key point of production preparation. They are mostly castings and single-piece production, the manufacture of casting model is the key to the preparation of blank. Generally use solid casting (a kind of disappearing type).
2. due to the large size of the outline of the automobile cover die, so processing it requires large mechanical processing equipment. Commonly used are: gantry planer, gantry milling machine, floor boring and milling machine, gantry CNC milling machine, multi-axis CNC milling machine, etc. In addition, in order to adjust the die, also need a large grinding press and die test press.
3. The key point of the manufacturing process of automobile panel stamping die is the machining of working parts. Because it is a combination of three – dimensional surface, so it is difficult to process, precision is not easy to guarantee. Improving the precision of NC machining is the key to improve the precision of die and shorten the manufacturing cycle.
4. The assembly, grinding and pressure testing of the die are very important manufacturing processes. In particular, the proportion of pressure test adjustment in the whole design and manufacturing time is very large. With the development of technology and the improvement of machining precision, the period of grinding and debugging will be shortened gradually.
5. A cover generally needs more than two sets of die, and each set of die manufacturing sequence is subject to process verification needs. The conventional manufacturing sequence is to first manufacture drawing die, then all kinds of forming die, repair die.