The characteristics, advantages and disadvantages of the toothed timing belt are studied. It points out the precautions and basic requirements for daily prevention of textile machinery when using toothed timing belts. This paper discusses the mechanism of the mechanical wave generated by the 'climbing tooth' phenomenon of the toothed synchronous belt, and puts forward methods, points and solutions to prevent the 'climbing tooth' phenomenon. It has important guiding significance for textile enterprises using toothed timing belts.
There are two types of synchronous belt with single-sided teeth and double-sided teeth, referred to as single-sided belt and double-sided belt. The double-sided belt is divided into symmetrical tooth shape (DA) and staggered tooth shape (DB). There are two types of synchronous belt teeth: trapezoid tooth synchronous belt and arc tooth synchronous belt. The timing belt models are divided into seven types: lightest MXL, ultra-light XXL, extra-light XL, light L, heavy-duty H, extra-heavy XH, and super-heavy XXH. Trapezoid tooth synchronous belt transmission has existing standards (GB11361～11362–89).
Under the specified tension, the straight-line distance between the center lines of two adjacent teeth is called the pitch, which is denoted by p. Pitch is the most basic parameter of synchronous belt transmission. When the synchronous belt is bent perpendicular to its bottom edge, the perimeter that keeps the original length in the belt is called the pitch line, and the pitch line length is expressed by LP. The tooth shape of the synchronous belt pulley is recommended to use involute tooth shape, which can be processed by Fancheng method. Straight-edge tooth shapes can also be used.
1 Tooth shape with belt characteristics and main advantages
1.1 Accurate molding makes the timing belt teeth completely match the groove of the pulley
1.2 High-strength nylon fiber cloth protects the tooth face
1.3 The maximum load force can reach 1000kW
1.4 It is not easy to slip when starting
1.5 Large transmission speed range
1.6 No need for lubricating oil or adjustment due to extension and wear
1.7 Higher mechanical transmission power ratio
1.8 Constant operating speed
1.9 Long working life
2, polyurethane timing belt
It is based on a high-strength low-strength chemical fiber rope or steel wire. It is covered with polyurethane casting glue and has a double-sided or single-sided arc-shaped tooth shape. It has various advantages such as oil resistance, wear resistance, shock absorption, and low noise.
Features: It has the respective advantages of gear transmission, chain transmission and belt transmission. It does not require lubrication, has small slip, no pollution, low noise, compact structure and smooth operation.
The mechanical ripple caused by the 'climbing tooth' phenomenon in the use of toothed synchronous belt and the countermeasures
More and more textile equipment uses toothed belts.
3. The mechanism of 'tooth climbing' phenomenon in the use of toothed synchronous belt
Although the synchronous belt drive has many advantages, it also has many defects, such as: short life, not wear-resistant, serious tooth peeling phenomenon, bad conditions such as meshing, tooth jumping, and vibration.
With the transmission error generated by the transmission process of the synchronous belt and the transmission motion, the synchronous belt will rest on the surface of the tooth profile, due to the accumulation of N times of errors. It will make the tooth climb to the top circle of the pulley, and make the synchronous toothed belt slide on the top circle of the pulley. This is the so-called 'climbing tooth' phenomenon;
In addition to the above reasons, the phenomenon of 'climbing teeth' may occur, as well as:
3.1 The tension of the timing belt is inappropriate.
3.2 There is oil on the surface of the timing belt or the toothed wheel
3.3 The toothed wheel of the transmission and the toothed wheel are not on the same plane (that is, the difference in parallelism);
3.4 Synchronous toothed belt is an elastic body, and the pitch of the tooth will change during the manufacturing and force transmission process, causing the pitch of the synchronous belt tooth and the pulley tooth to be unequal, resulting in a pitch error. Excessive pitch error will make the transmission unstable and produce vibration and tooth climbing;
3.5 When the starting is frequent and there is an impact load, the tooth will jump out of the tooth groove of the pulley, and the tooth will also be generated.
3.6 In the application of synchronous toothed belt, it is necessary to prevent overload, otherwise it is easy to produce 'climbing tooth' phenomenon.
3.7 Some companies use synchronous toothed belts, but the size of the 'tension' of the supporting tension wheel is not well grasped. Either desperately increase the tension, or the tension is insufficient.
3.7.1 The danger of excessive tension of the tension wheel: It is well known that when the tension of the tension wheel is too large, and the rigidity of the tension wheel shaft is insufficient, the head of the tension wheel will be bent and deformed, thereby causing a jump, which is harmful. , It makes the transmission become unstable and produces high-frequency oscillations, thereby generating higher-order harmonics.
3.7.2 Insufficient tension of the tension wheel increases the undesirable conditions caused by the 'climbing tooth' phenomenon of the toothed timing belt.
Synchronous toothed belt 'climbing' phenomenon is very harmful to textile equipment, such as: draw frame, carding machine, roving frame, etc. The 'tooth climbing' phenomenon is one of the important reasons for generating mechanical waves! Moreover, this 'climbing tooth' phenomenon often has the characteristics of irregularity, so it often produces more complex 'multiple mechanical waves'. The generation of such 'multiple mechanical waves' is sometimes asexual, which makes it difficult to find the trace. Increased the complexity and difficulty of solving mechanical waves!
4Countermeasures to solve the phenomenon of 'tooth climbing' in the use of toothed synchronous belt
4.1 To ensure the accuracy of the transmission, for the manufacturer, it is necessary to improve the manufacturing precision of the synchronous belt teeth to ensure that the pitch is equal to the pitch of the pulley teeth.
4.2 Solve the pitch error and accumulated error in manufacturing
4.3 Appropriate pre-tensioning: The timing belt drive must have proper tension. For example, the FA317A drawframe product manual has a tension adjustment table to facilitate tension adjustment during maintenance and ensure that there is no mechanical wave caused by improper tension.
4.4 Ensure that there is no oil stain on the surface of the timing belt and the toothed wheel during use.
4.4 The toothed wheel and the toothed wheel must be ensured to be parallel in manufacturing and installation;
4.5 Solve the processing accuracy of the toothed wheel and prevent the vibration of the timing belt;
4.6 Machinery using toothed belt transmission should avoid frequent starting as much as possible to prevent its life from being shortened;
4.7 Regularly clean and maintain the surface of the toothed belt and the toothed wheel with absolute ethanol to ensure no oil pollution;
4.8 Regularly check the tension of the toothed belt;
4.9 In combination with the analysis of the spectrogram of the mechanical wave detection of semi-finished products, problems are found and solved in time.
5.1 Tooth synchronization with superior transmission performance;
5.2 The transmission error caused by long-term use of toothed synchronous belt, the tension of the synchronous belt is too small, the oil on the surface of the synchronous belt or the toothed wheel, the pitch error during operation, frequent starting and impact load, and overload will all cause Tooth phenomenon
5.3 The phenomenon of 'tooth climbing' using toothed timing belts is the root cause of mechanical waves;
5.4 The author proposes 9 points of measures to prevent the 'tooth climbing' phenomenon of the toothed synchronous belt, which can effectively solve the mechanical wave caused by the 'tooth climbing' phenomenon.