Spinning technology of V-belt pulley of the hottes

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Spinning process of V-type pulley for automobile engine

[Abstract] in order to improve product quality, save materials and improve productivity, split spinning process is used to spin the drawn blank into V-type or multi wedge pulley for automobile engine. The product quality and technical performance of the spinning pulley developed have reached the level of similar international products

key words: Automobile Engine V-belt pulley spinning

1 introduction

belt pulley is an important mechanical transmission part, which is widely used in the transmission of various mechanical equipment in automobile, agricultural machinery and light textile industry. The traditional manufacturing process of the pulley is to use the casting process to make the blank, and then make it by cutting. The disadvantages of the traditional manufacturing process are serious waste of materials, low productivity, low product accuracy, and the pulley products produced need to be balanced due to low accuracy. In order to overcome the shortcomings of traditional technology and realize the lightweight of belt pulley, countries all over the world have been committed to the research and development of sheet metal hydraulic bulging [1] or spinning forming sheet metal belt pulley in recent 30 years [2], [3]. Among them, the split spinning belt pulley process and special belt pulley spinning machine developed by leifeld in Germany are of great significance. The belt pulley produced by this process and equipment has been rapidly applied to automotive engines, and has driven the research and application of various countries in this field. The research work in this field was first started at the Technology Research Institute of the Ministry of Aeronautics and Astronautics in Beijing, China, and the first spinning V-belt pulley production line in China was established in Jingxian County, Hebei Province 15 years ago [4], using the introduction of German special spinning machine and spinning technology, and the products are matched with Shanghai Santana, Beijing Cherokee, Tianjin Xiali and other models. In order to meet the needs of the development of car products of China FAW Group Corporation and realize local and nearby matching, with the support of FAW Group and relevant departments of Changchun City, we began the research on the spinning process of V-belt pulley of automobile engine in 1998, and developed qualified products by the end of 2000. After the products passed the inspection of the National Automobile Quality Supervision and inspection center, they were tested in batches, and were confirmed as supporting products by FAW Group

2 spinning forming process of V-shaped belt pulley

2.1 spinning process principle of V-shaped belt pulley

as shown in Figure 1, put the belt pulley blank 3, which is drawn into a cup and has a central hole, into the core mold workpiece of the special spinning machine, after clamping, the core mold and the blank rotate with the spindle of the spinning machine, and then the spinning wheel 1 with hard sharp angle makes a gradual radial feed and wedge into the edge of the rectangular section of the blank, Therefore, the edge surface is split into two parts in a "Y" shape. The cross-sectional shape of the pulley groove can be obtained by orderly and continuous feeding, and the spun metal produces continuous local plastic deformation

1 - spinning pulley 2 - core die 3 - workpiece

Figure 1 principle of V-belt pulley splitting spinning forming

2.2 classification of V-belt pulley and its spinning forming process

according to the structure and spinning deformation characteristics of V-belt pulley, it can be divided into three categories: folding belt pulley (Figure 2a), multi wedge belt pulley (Figure 2b) and split belt pulley (Figure 2C)

Figure 2 classification of V-belt pulley

because the deformation characteristic of folding belt pulley is to change the shape of blank section along the axial direction, and the thickness of sheet metal is basically not reduced. Therefore, in order to control the bottom of the V-groove of the belt pulley from thinning, a gradual transition spinning process should be adopted in the spinning process. In addition, pre spinning forming and fine spinning forming are two steps of forming, and at the same time, the blank should be pressurized axially to supplement materials and produce folding

the forming of multi wedge pulley is to first use the pre spinning wheel to load and feed the blank radially, so that the blank will produce a predetermined local thickening in the thickness direction, and then use the fine spinning wheel for fine spinning, so as to form a multi-v wedge pulley after thickening

the forming of the split pulley is to use the wedge spinning wheel to align with 1/2 of the rectangular section of the blank thickness for radial feed, and split into two in the thickness direction. Then use the forming roller to spin into a V-shaped groove

2.3 spinning equipment and process equipment

2.3.1 spinning equipment

domestic vertical belt pulley special spinning machine is selected as the main equipment. The main technical indicators of the spinning machine are shown in Table 1. We use two 45t three position spinning machines and one 20t two position spinning machine on the production line, and match the general equipment such as hydraulic press, punch, plate cutting electromechanical swimming coating line, etc. Table 1 main technical parameters of special rotary presses such as glass, metal and hard plastic packaging

Table 2 range of processed products

2.3.2 spinning process equipment

(1) shaping and refurbishing mold

in order to ensure product quality and positioning accuracy, deep drawing blanks need to be shaped to improve coaxiality and flatness. In addition, the outer edge of the workpiece to be spun shall be repaired to ensure that the surface is flat. References for the design of reshaping die and reshaping die [5]

(2) spinning wheel and core mold

spinning wheel is one of the key factors to make the spinning process achieve good results. The outer diameter dimension, groove shape and surface roughness of the pulley are all guaranteed by the rotating pulley. When working, the roller is in partial contact with the blank, bearing huge contact pressure, intense friction and high working temperature

therefore, the working conditions require that the material of the spinning wheel should have sufficient strength, hardness, toughness and wear resistance. We use Cr12MoV high chromium tool steel to manufacture the spinning wheel, and at the same time, we use a more strict heat treatment process. Before quenching, we normalize to eliminate the stress, and the quenching hardness is 57~59hrc

the shape and size of the roller shall be designed according to the requirements of the product drawing for the groove type and groove angle of the pulley, and the diameter of the roller shall be determined according to the requirements of the spinning equipment for the maximum and minimum size of the roller. In order to increase the service life of the spinning wheel, its working surface should be polished to make its surface roughness reach 0.4 mm

core mold is an indispensable process equipment in the spinning process. During spinning, the outer surface of the core mold is in contact with the inner surface of the pulley, which plays a supporting and positioning role on the one hand, and on the other hand, its working surface also bears considerable local force and severe friction caused by material deformation and flow. Therefore, the requirement for the core mold is to give consideration to strength, stiffness and toughness. In practice, we use 20CrMnTi steel to make the core mold, and the surface quenching hardness is 45hrc

in order to realize automatic mold unloading and improve productivity, we have designed a combined core mold with eccentric support wheel structure. Its working principle is: using the non rotation ejected from the spinning machine, an eccentric bearing body is fixed with it through long bolts, and the eccentricity is fixed on the eccentric bearing body through a circle of rollers. In this way, the eccentric can rotate and be fixed in the center. After repeated tests, the automatic unloading of spinning pulley is realized

2.4 production process flow

v-belt pulley spinning production line process flow and products of each process are shown in Figure 3

Figure 3 V-belt pulley spinning line process flow and products in each process

3 product technical performance indicators and economic benefit analysis

3.1 comparison of main technical performance indicators of products with similar products at home and abroad

the V-belt pulley products we spin have been tested by the National Automobile Quality Supervision and Inspection Center (Changchun Automobile Research Institute) in accordance with the enterprise standard q/cacb1000-3-1996 of China First Automobile Group Corporation, The sample inspection and 4 industry convergence were carried out, and the bench test of 80 hours was continuously accelerated. The size is qualified after inspection, and no abnormality is found after 480 hour reliability test. The inspection conclusion is that the product is qualified

see Table 3 for the comparison of the main technical performance indexes of the V-type spinning pulley we developed and produced with similar products at home and abroad. Table 3 main technical performance indicators of products

3.2 economic benefit analysis and domestic market demand analysis

using sheet metal spinning V-belt pulley has significant economic benefits:

(1) the utilization rate of materials is higher, which is 15% to 30% higher than that of traditional processes

(2) the product is light, 30% - 60% lighter than the cutting pulley

(3) high productivity (2-3 pieces/minute), more than 4 times higher than the traditional process

(4) the moment of inertia of the product is small, and the balance is only to ground the three addresses well, so rebalancing is not required

total spinning V-shaped pulley can reduce the production cost by 25% - 30% compared with the traditional method

by 2000, China had produced 2million vehicles of all kinds. If 4 spinning V-shaped pulleys are used for each vehicle, 8million pulleys are required for supporting loading only one year. The market demand for social accessories is calculated by 1/4 of the supporting loading consumption, and the annual demand of the accessories market is 2million. Therefore, the total demand for pulleys in the domestic automotive industry is between 10million and 15million pieces. With the rapid development of China's automobile industry, the demand for spinning V-belt pulley will be increasing

4 conclusion

v-belt pulley spinning process is a fast and efficient new continuous local plastic forming process. Compared with the traditional process, it has comprehensive economic benefits such as material saving, energy saving and cost reduction. The spinning V-belt pulley is of good quality and does not need balancing treatment. It is especially suitable for the belt pulley of automobile engine. The pulley produced by this process has been matched with the CA488 Engine of China First Automobile Group Corporation and the water pump, crankshaft and fan wheel of ca7120 Hongqi car. Spinning pulley can also be popularized and applied in machinery, light industry, household appliances and other industries, which has a broad domestic market and application prospects


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