A bidirectional wedge overrunning clutch has a shaft hole at one end connected with a driving shaft and a shaft hole at the other end connected with a driven shaft. When the outer ring is stationary and the driving shaft rotates clockwise or counterclockwise, the driven shaft rotates synchronously, but when the driven shaft is subjected to external force torque, it cannot rotate clockwise or counterclockwise. It is often used with ball screw pairs or other parts as a mechanism to prevent reverse rotation, and can also be used alone to accurately locate, transmit torque or cut off torque. Zhu Beijing Institute of Mechanical Technology
Beijing Xinxing Chaoyue Technology Development Company Kong Qing Tang Kong Wei Zhu Zicheng
This paper introduces the development of wedge overrunning clutch at home and abroad, and expounds the characteristics, structural forms and application scope of wedge overrunning clutch.
Wedge overrunning clutch; trait
1, development and reaction of wedge overrunning clutch
Overrunning clutch is one of the basic components of mechanical transmission. It is a kind of clutch with self-clutch function by changing the speed or rotation direction of the driving part and the driven part, and it is widely used. Roller overrunning clutch has a long history. According to the literature, 1878 was included in the German DRP2804.47h5 patent with the title of "reversing motor" for reversing gears. In the following hundred years, the roller overrunning clutch has been continuously developed and improved, with more structural types and more common applications.
Wedge overrunning clutch is a new type of clutch developed after roller overrunning clutch. Since it came out, it has been widely used in mechanical transmission because of its advantages such as large bearing capacity, reliable self-locking, light reverse release, compact structure and convenient operation. First of all, the United States has developed and popularized automobiles and airplanes. For example, the United States used it on Boeing 707, F4-C bomber and M 102- 105 light howitzer. It is also widely used in Japan and Germany.
In recent years, with the development of new products and the need of localization of imported products, wedge overrunning clutch has developed rapidly, its structure, performance and reliability are becoming more and more perfect, the types and specifications of clutch are more complete, and the product quality is gradually improved. CK series wedge overrunning clutch produced by Beijing Xinxing Beyond Technology Development Company can not only meet the needs of domestic scientific research and production. It also replaced the overrunning clutch on corrugated paper production line and oxygen-free copper production line imported from Japan, America, Italy and other countries, and the use effect was good. At present, there are also exports, which have good development potential and prospects.
Wedge overrunning clutch is often matched with ball screw pair or other parts as a mechanism to prevent reverse rotation, and can also be used alone as a clutch with self-clutch function to accurately locate, transmit or cut off torque between driving shaft and driven shaft. Therefore, it is called backstop or one-way bearing. Widely used in packaging machinery, printing machinery, food machinery, light industrial machinery, agricultural machinery, metallurgical mines, petrochemical industry, machine tools, automobiles, weapons, aviation, power stations and other mechanical equipment.
2. Characteristics of wedge overrunning clutch
Wedge overrunning clutch is to place a wedge element (wedge) between the inner ring and the outer ring (raceway), so that one can transmit torque when it rotates, and the other has relative idling performance. Only when the inner and outer rings rotate in the same direction and at the same speed can torque be transmitted, otherwise it is a relative sliding state, which is called transcendence.
1) raceway shape
There are two kinds of raceway forms of wedge overrunning clutch: the raceway of inner and outer rings is circular, and the inner ring is processed with several concave annular grooves.
(1) The inner ring is complete (see figure 1a). The inner and outer rings of the clutch are smooth cylinders, and the wedge angle of the wedge cannot exceed the minimum friction angle between the wedge and the inner and outer rings to ensure that it does not slip when working. When designing, it is generally 3? 0? 2-4? 0? 2. In practice, at the beginning of the wedge angle, the wedge angle is about 2? 0? 2-2.5? 0? 2. When the inner and outer rings are elastically deformed, the wedge angle increases accordingly.
(2) The inner ring has a concave circular groove shape (see figure 1b). The radius of the annular groove of the wedge and the inner ring is the same, so that they are in surface contact, which improves the stress state and improves the bearing capacity and service life of the wedge. However, due to the influence of structure, the number of wedges has decreased.
2) Wedge shape
Wedge shapes used in wedge overrunning clutch are mostly special shapes, such as fist shape and shoe shape. When designing the clutch, wedges with different shapes can be selected according to the functional requirements.
3) Wedge-type overrunning clutches and roller-type overrunning clutches have their own characteristics due to the different wedge elements placed between the inner and outer rings (see table 1).
3, wedge overrunning clutch selection calculation
In order to ensure the reliability of the clutch, when designing and selecting the clutch, it is usually necessary to make clear the comprehensive function of the clutch in the transmission system, and select the variety and type of the clutch from the overall design of the transmission system. The selection of specifications is mainly based on the calculated torque.
1) clutch torque.
The main parameter of clutch is rated torque. When selecting the clutch, the transmission torque should meet the following relationship: t
Where t-theoretical torque, n·m；; Tc-calculated torque, n·m；;
TN-nominal torque, n·m；;
[t]- allowable torque, n·m；;
[tmax]- maximum allowable torque, n·m；;
Tmax-maximum torque, n m.
2) Calculation of clutch torque
The calculated torque of clutch is calculated according to the power of transmission system, working speed, reserve coefficient and its related factors.
Tc=？ 0? 8T
Where TC-calculated torque, n·m；;
? 0? 8- Reserve coefficient (generally1.2-3.2);
T-theoretical torque, n.m. reserve coefficient? 0? The value of 8 is related to the prime mover, working machine performance, clutch structure and other factors. Generally, the working conditions are good and the load is light. 0? 8 value takes a small value; Poor working conditions and heavy load. 0? The value of 8 is greater.
4. The structure and application scope of wedge-type overrunning clutch According to GB 10043- 1988 clutch classification, wedge-type overrunning clutch can be divided into contact type, non-contact type and bidirectional type, and the first two types are actually unidirectional. Table 2 lists the structural forms and application scope of various types of wedge overrunning clutches.
Figure 1 shape of inner ring of wedge overrunning clutch
Table 1 Comparison of Wedge Type and Roller Type Overrunning Clutch
& ltdiv align = center & gt Top wedge overrunning clutch The roller overrunning clutch has a large bearing capacity, and the radius of curvature of the arc angle between the wedge and the raceway is larger than the radius of the roller in the roller clutch, so the contact stress is small. Large carrying capacity. Under the condition of the same raceway size, the number of rollers is small, the contact stress is large and the bearing energy is large. Self-locking performance is reliable, and reverse release is light and reliable. When the transmission efficiency is 0.94-0.98. 94-0.99 overload,
Working conditions are extremely overloaded. One or several wedges may rotate beyond the maximum support range, causing their wedges to turn over. When the torque is reduced, the wedge cannot be reset. But this is an abnormal state of use. In the case of extreme overload, the roller is easy to slide and the self-locking fails. When the torque is reduced, the roller is reset and can be wedged again for normal operation. Parts wear wedge can't rotate, and the contact part between wedge and inner and outer raceway is limited in a short working arc, which is easy to wear facet. When transmitting torque, the wedge type has smaller diameter, lower circumferential speed and more wedges, thus reducing the wear of wedges and prolonging the service life. The roller can rotate freely in the raceway, and it can remain round after wear. The wedging state and separation state of the contact point between the roller and the inner and outer rings are different, and the wear is more uniform. Dents are often worn at the contact point between the star wheel and the roller, which affects the use of manufacturing technology. Wedge block is made by special technology, mass production and convenient processing. The inner and outer rings are easy to process and assemble. The processing of star wheel is complicated and the manufacturability is poor.
Table 2 Structure and application range of wedge overrunning clutch
One-way and two-way contact type non-contact structure type basic non-inner ring bearing type non-contact bearing type1no. cka 1-cka 26 ckb 1-ckb 16kz 1-ckz 40 ckf 1-ckf 70 cks 65438。 Indicates the connection type: key connection, bolt connection, gear connection, pulley connection and sprocket connection. The limit speed is 800-2,500r/min, and the rated torque is 31.5-2,800n.m. It is often used for mechanical transmission of packaging, printing, food machinery, bucket elevator conveyor, etc. The limit speed is1000-2,000r/min, and the nominal torque is 35.5-/kl. The limit speed is 600- 1500r/min and the rated torque is180-8000 n m, which is often used in packaging machinery, lifting and transporting machinery, metallurgy, mining, petrochemical industry, power station and so on. (also known as backstop). The limit speed is 400- 1500r/min, and the rated torque is 400-2,500 n m, which is often used in hoisting and transportation machinery, hoists, metallurgy, mines, cement machinery and other places with reducers. As an anti-reverse mechanism, it is generally used at high speed. Nominal torque: 20-300 N m, which is often used with ball screw pairs or other parts as a mechanism to prevent reverse rotation, and can also be used as a precise positioning alone.
Reference 1 kong qingtang, structure and application of wedge overrunning clutch, clutch technology (part 3), 1993.
2 Compilation of Practical Mechanical Design Manual, Volume II (2nd Edition), Beijing: Machinery Industry Press, 1995.
Editor-in-Chief, Mechanical Design Manual (3rd Edition), Volume II, Beijing: Chemical Industry Press, Zhuji Special Clutch Factory, 1994.
Our factory is a professional manufacturer of overrunning clutches, specializing in producing and * * * all kinds of wedge overrunning clutches, backstops, roller overrunning clutches and backstops. By absorbing and digesting imported products, we have successfully developed two new types of overrunning clutches, namely, special-shaped roller overrunning clutch (Japanese structure) and wedge overrunning clutch (German structure). Compared with traditional clutches, these two products have the following outstanding features:
1, the transmission torque is large, and the transmission kink of the same size is increased by more than 100%.
2. The sensitivity is high, and the relative rotation angle between the driving shaft and the driven shaft is less than 65438 0.5/.
3. Long service life: 6 *100000000 times.
4. When the adaptive range is greatly exceeded, the limit speed is 3000 rpm.
5. Excellent working environment, working under grease lubrication.
Overrunning clutch is a clutch with self-clutch function by using the speed change or rotation direction change of driving and driven parts. It is the basic part of mechatronics mechanical transmission. Its connection forms are divided into: key connection, bolt connection, gear connection, pulley connection, sprocket connection and so on. . Its main function is to prevent reverse rotation, accurately locate, transmit torque or cut off torque. Therefore, some industries call it backstop or one-way bearing. Widely used in machine tools, packaging machinery, printing machinery, light industrial machinery, textile machinery, petrochemical machinery, cement machinery, metallurgical machinery, lifting and transportation machinery, reducers, power generation equipment and test beds. Products have been sold all over the country and adopted by many manufacturers. Its performance index is higher than that of domestic similar products, reaching or close to imported similar products, and can replace imported products. We can develop and produce standard and non-standard overrunning clutches according to user requirements.
200111/05 was transferred to Guangzhou Zhao Yu technology co., ltd.