Abstract : A new liquid die forging process for aluminum alloy wheel hubs is proposed. The new process realization conditions and process measures are verified by experiments. The product performance is better than the current low pressure casting method. The equipment is simple and has good economic benefits.
Key words: liquid die forging; wheel hub; aluminum alloy
I. Introduction
The aluminum alloy wheel hub is a replacement product of steel wheel hub. It has the advantages of light weight, fast heat conduction, beautiful and luxurious, energy saving and safety, etc. It has been widely used in cars and other light passenger cars at home and abroad. With the rapid development of China's automobile industry and the increase in demand for foreign parts, the market capacity is considerable. At present, the methods for manufacturing aluminum alloy wheels at home and abroad are mainly divided into two categories: one is forging method, and the most advanced technology in foreign countries is composed of continuous casting process and three forging processes. Although the quality is good, the yield is only About 50%, the price is expensive. The other type is casting, gravity casting and low pressure casting. Gravity casting products have serious defects such as shrinkage, looseness, and porosity, low mechanical strength, low yield, and have been eliminated abroad. At present, most of the low-pressure casting methods are adopted at home and abroad. The quality and yield of the products are improved. However, the process is complicated and the equipment investment is too large. It is necessary to invest more than 100 million yuan in equipment imported from abroad with an annual output of 300,000 pieces. The liquid die forging method is used to crystallize the aluminum alloy under high pressure, and a certain amount of deformation is generated during the crystallization process, thereby eliminating defects such as shrinkage, porosity, porosity and the like, and the product has excellent mechanical properties close to forgings and fine castings. High precision and high precision for one precision molding, and the investment is much lower than the low pressure casting method.
Second, the process characteristics of the wheel hub and the key to the process
The hub is a part as shown in Fig. 1. Similar to a shallow cup, the wall is thin, the wall thickness is almost uniform, the rim diameter is large, and the height is moderate, which is basically suitable for liquid die forging. The main difficulty in manufacturing is that when direct liquid die forging is used, a deeper cold separation is easily formed between the rim and the original casting level, and measures must be taken to avoid it.
Key words: liquid die forging; wheel hub; aluminum alloy
I. Introduction
The aluminum alloy wheel hub is a replacement product of steel wheel hub. It has the advantages of light weight, fast heat conduction, beautiful and luxurious, energy saving and safety, etc. It has been widely used in cars and other light passenger cars at home and abroad. With the rapid development of China's automobile industry and the increase in demand for foreign parts, the market capacity is considerable. At present, the methods for manufacturing aluminum alloy wheels at home and abroad are mainly divided into two categories: one is forging method, and the most advanced technology in foreign countries is composed of continuous casting process and three forging processes. Although the quality is good, the yield is only About 50%, the price is expensive. The other type is casting, gravity casting and low pressure casting. Gravity casting products have serious defects such as shrinkage, looseness, and porosity, low mechanical strength, low yield, and have been eliminated abroad. At present, most of the low-pressure casting methods are adopted at home and abroad. The quality and yield of the products are improved. However, the process is complicated and the equipment investment is too large. It is necessary to invest more than 100 million yuan in equipment imported from abroad with an annual output of 300,000 pieces. The liquid die forging method is used to crystallize the aluminum alloy under high pressure, and a certain amount of deformation is generated during the crystallization process, thereby eliminating defects such as shrinkage, porosity, porosity and the like, and the product has excellent mechanical properties close to forgings and fine castings. High precision and high precision for one precision molding, and the investment is much lower than the low pressure casting method.
Second, the process characteristics of the wheel hub and the key to the process
The hub is a part as shown in Fig. 1. Similar to a shallow cup, the wall is thin, the wall thickness is almost uniform, the rim diameter is large, and the height is moderate, which is basically suitable for liquid die forging. The main difficulty in manufacturing is that when direct liquid die forging is used, a deeper cold separation is easily formed between the rim and the original casting level, and measures must be taken to avoid it.
figure 1
The key to affecting the internal crystal quality and mechanical properties of the workpiece is the control of the temperature field and the stress field, and there are many factors affecting the temperature field. Therefore, the ideal temperature-time curve must be found through experiments and calculations. The stress field is directly related to the elimination of defects such as shrinkage, porosity and porosity in the workpiece. It is necessary to determine the proper stress field distribution to lay the foundation for obtaining high quality workpieces.
Third, mold design and determination of forming conditions
Mold design
Considering that there may be defects such as inclusions on the surface of the workpiece, the thickness dimension must have a certain machining allowance. Therefore, 0.5 mm is added to the thickness of the part drawing, and the draft angle is 1.5°, and the forging drawing is drawn. The mold is designed based on the figure. According to the structural characteristics of the workpiece, a direct liquid die forging method must be adopted, and the concave die adopts a vertical parting surface for the workpiece to be discharged. The use of vertical splitting requires a horizontal locking device. Considering the equipment constraints, a tapered retaining ring locking device is used, see Figure 3 in Figure 2. In operation, after casting metal in the die formed by the members 4, 6, and 8, the upper mold descends, and the member 3 first presses the members 4 and 8 to form a clamping mold, and then the punch 6 is press-formed, and after holding, the punch is pressed. 6 With the upward movement of the upper mold, the piece 3 is still pressed 4, 8 under the action of the spring, so that the male mold is demolded, the spring pressing force should be greater than the punching force of the punch, and the last member 2 is driven upward, and the parts 4 and 8 are separated. Take out the workpiece. Since it is a test mold, the guide is mainly guided by the equipment. The clamping stroke is controlled by the pressing force, which may cause errors in the thickness dimension of the spoke portion, but does not affect the test effect but greatly simplifies the quantitative pouring device.
Third, mold design and determination of forming conditions
Mold design
Considering that there may be defects such as inclusions on the surface of the workpiece, the thickness dimension must have a certain machining allowance. Therefore, 0.5 mm is added to the thickness of the part drawing, and the draft angle is 1.5°, and the forging drawing is drawn. The mold is designed based on the figure. According to the structural characteristics of the workpiece, a direct liquid die forging method must be adopted, and the concave die adopts a vertical parting surface for the workpiece to be discharged. The use of vertical splitting requires a horizontal locking device. Considering the equipment constraints, a tapered retaining ring locking device is used, see Figure 3 in Figure 2. In operation, after casting metal in the die formed by the members 4, 6, and 8, the upper mold descends, and the member 3 first presses the members 4 and 8 to form a clamping mold, and then the punch 6 is press-formed, and after holding, the punch is pressed. 6 With the upward movement of the upper mold, the piece 3 is still pressed 4, 8 under the action of the spring, so that the male mold is demolded, the spring pressing force should be greater than the punching force of the punch, and the last member 2 is driven upward, and the parts 4 and 8 are separated. Take out the workpiece. Since it is a test mold, the guide is mainly guided by the equipment. The clamping stroke is controlled by the pressing force, which may cause errors in the thickness dimension of the spoke portion, but does not affect the test effect but greatly simplifies the quantitative pouring device.
figure 2
2. Determination of forming process conditions
(1) Smelting and mold preparation of aluminum alloy
The hub is subjected to a large impact load when it is in operation, and is usually made of an aluminum-silicon alloy. ZL107 alloy is selected and smelted in an electric furnace to control the smelting temperature more accurately, and it is preferable to carry out refining and degassing treatment. Due to the long metal filling distance, in order to increase the filling, the pouring temperature is increased to 730 ° C, the mold should be preheated to 310 ° C before work, heated by electric resistance wire, preheating and simultaneously applying lubricant, in order to smoothly demould. Graphite oil is used as the lubricant. In order to ensure uniformity, it is best to use spraying. If the casting temperature and the mold temperature are too high, the surface of the workpiece may be rough or even soldered. The temperature is too low and the metal is cooled too fast, which makes it difficult to fill and form.
(1) Smelting and mold preparation of aluminum alloy
The hub is subjected to a large impact load when it is in operation, and is usually made of an aluminum-silicon alloy. ZL107 alloy is selected and smelted in an electric furnace to control the smelting temperature more accurately, and it is preferable to carry out refining and degassing treatment. Due to the long metal filling distance, in order to increase the filling, the pouring temperature is increased to 730 ° C, the mold should be preheated to 310 ° C before work, heated by electric resistance wire, preheating and simultaneously applying lubricant, in order to smoothly demould. Graphite oil is used as the lubricant. In order to ensure uniformity, it is best to use spraying. If the casting temperature and the mold temperature are too high, the surface of the workpiece may be rough or even soldered. The temperature is too low and the metal is cooled too fast, which makes it difficult to fill and form.
Next page
Genuine Synchronizer Ring OEM, Genuine Synchronizer Ring, Santana Synchronizer Inner Ring, 1988 Santana Synchronizer Ring
ShaoXing Change Auto Synchronizer Ring Co.,Ltd , https://www.sxcjautoparts.com