For details, please refer to the PDF file of the "Modern Parts" 2007 issue 5 or the bottom of the download page. The development of the manufacturing process of automotive parts is an important part of new product development. It will directly affect a product quality and development cycle, so a high-quality product must be guaranteed by a high-quality manufacturing process. At present, China's production technology level in developed countries is far from enough. Many foreign advanced technologies are used less in China. How to design and manufacture products abroad has been successfully developed and manufactured in China, which is a difficult problem we face. The use of domestic resources to continuously improve their own innovation capabilities, so that the quality of products meet or close to the product design and technical requirements, to improve our development quality, shorten the development cycle, reduce development costs have a certain significance.
The transmission control mechanism is a key component of the car, mainly completing the functions of 1/2, 3/4, 5/reverse and related sensing components, as shown in Figure 1. Its dimensional accuracy requirements are high, including many parts and classes, including stamping parts, castings, machine parts, standard parts, etc., so the manufacturing process is very complicated, involving a wide range, including stamping, casting, forging, machining, welding, riveting, Assembly, heat treatment, surface treatment, etc., basically cover all processing processes of mechanical manufacturing. The manufacturing and assembly accuracy requirements of parts and assemblies are also high. The same parts may have different processes. According to our existing practice basis, the main process features and related tools in the process planning of the control system of the automotive transmission are respectively introduced below. Analysis program.
(a) MG car gear assembly (b) Peugeot 307 gear shift assembly Figure 1 Transmission control mechanism assembly stamping process......
FIG 4 fine blanking die
casting structure <br> <br>
Casting parts in the transmission are also widely used. According to the materials, they are generally divided into copper castings, spheroidal castings, and steel castings, which are mainly connected with shaft parts to complete shifting or gear selection, as shown in Figure 5. The casting processes widely used in China include sand casting, investment casting, etc. Since these parts are small precision castings, the influence of the weight, material and casting of the parts will be encountered during the development of the casting supplier. Below 0.5kg, for example, it is possible to use sand casting to produce a ductile iron material with good wear resistance (Fig. 2 shifting guide block), and it is difficult to develop this in China because the weight of the part is too small and the material requirements are high. Supplier of materials. Therefore, such parts only consider the use of other materials and casting processes, such as the 45 steel investment casting process, and then the high-frequency quenching of the functional surface to ensure the use of parts.
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The transmission part 5 in FIG casting
machining process <br> <br>
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Fig. 6 The three-dimensional effect diagram of the part drawing bracket fixture is shown in Fig. 7. The part 1 is clamped on the lathe chuck and is matched with the top end 2 of the left end of the part 5, and the left and right ends of the mandrel 5 are cut and grooved by a wire. The tapered cones are matched with the tip 2 and the taper of the live tip of the machine tool, so that the workpiece can be expanded on the mandrel to prevent radial runout. The circumferential positioning of the workpiece is achieved by the workpiece positioning block 4, which is axially positioned against the steel ball in the workpiece positioning block 4 under the action of the spring force on the right plane of the expansion mandrel 3. This achieves complete positioning of the workpiece. In the processing, the mandrel 5 can be made into two pieces in order to exchange the clamping and improve work efficiency. Practice has proved that the fixture has good effect and better control all dimensional accuracy of the workpiece assembly in the axial direction. Through the improvement of the process scheme of “first welding after the carâ€, the sub-assembly is successfully developed in the project. Puzzle.
Fig. 7 Effect of the trough fixture 1. Fixed shaft 2. Top 3. Expanded mandrel 4. Workpiece positioning block 5. There are many examples of the mandrel in the cutting process by changing the process, such as “taking the car†and “ Good economic effects can be achieved by reasonable use such as “car grindingâ€, “drilling for the hinge†and “using the milling machineâ€.
Welding process
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FIG 8 is welded
riveting process the fixture <br> <br>
Riveting is a process that uses two extrusions of metal to join two parts. Because the riveting process has the advantages of high productivity, clean and pollution-free, low cost, etc., it has developed rapidly in foreign countries and has replaced the welding process in many fields. For example, the selection of the rocker arm and the reverse gear control assembly of the automobile transmission parts are riveted. For some parts with higher requirements, in addition to meeting the riveting strength, it is more important to ensure that the dimensions of the parts after riveting meet the requirements.
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Assembly process
The transmission control mechanism assembly process mainly combines the finished parts with some standard parts. Due to the small parts, the equipment used is generally a small manual press and a self-made manual assembly jig. Some assemblies such as washers, spring pins, springs, etc. are often completed during the welding and riveting process, rather than simply assembly, as shown in Figure 11 for the 1/2-stop, 5-reverse return springs and spring-restricted shaft punches. An example of a comprehensive fixture that is riveted into one. The jig is complicated, and the working process: the twisting function of the two springs is simultaneously completed by the hexagon socket head screw 12, the upper punch 13, the side bracket 14, and the spring stop pin 15; the spring is blocked by the spring pin 15 The torsion gap is larger than the workpiece spring limit pin at the outer diameter, so that it can be easily assembled to the correct position; in order to ensure the assembly safety, the upper punch 20 is forced by the press, and the spring is limited by the lower punch 6. The bottom end of the position pin is punched and riveted on the workpiece holder frame, and the riveting height is adjusted by the height adjusting block 16 and the hexagon socket head screw 4, and the fixing plate 7 is automatically returned after the riveting.
Figure 11 Fixture structure diagram In summary, the quality of a product process planning, in addition to the rich experience of the product process, must also fully understand whether the corresponding equipment and related tooling structure is realized, in order to formulate the most reasonable and effective The process route is adapted to the needs of mass production of products.
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