The synchronous toothed belt is called synchronous belt for short, also called timing belt. It is similar to the common V-belt, flat belt and other belt transmission modes, and is a flexible transmission form.The synchronous toothed belt is made of steel wire rope or glass fiber rope as the strength layer, and is covered withpolyurethaneorNeopreneThe inner circumference of the belt is made into a tooth shape to mesh with the tooth shaped pulley.Since the deformation of the strength layer is small after loading, it can keep the circumferential pitch of the toothed belt unchanged, so there is no relative sliding between the belt and the pulley, thus ensuring synchronous transmission and constant transmission ratio.[1]
The timing belt body is composed of a strong layer, a belt tooth layer, a cloth covering layer and an adhesive layer.The strength layer is the core rope with high tensile strength, usually glass fiber, polyaromamide fiber or steel wire rope with surface treatment.This layer mainly bears the tension of load.The belt tooth layer is the contact part between the synchronous belt and the pulley, and its tooth root line is roughly at the position of the pitch line to ensure that there is no circumferential pitch change when bending.Its tooth shape must be accurate and not easy to deform, so as to transmit motion accurately.The wrapping layer wraps the whole belt tooth layer to protect and prevent cracking.The adhesive layer is also called the belt back. Its main function is to stick the tensile material of the strong layer to the pitch line of the belt and protect the tensile material.
Specifications
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The working surface of the synchronous toothed belt and the rim surface of the pulley are made into corresponding tooth shapes, and the belt is driven by the belt that meshes with it.Generally, thin steel wire rope is used as the strong layer, and polyurethane orNeoprene。The center line of the strength layer is determined as the pitch line of the belt, and the perimeter of the pitch line is the nominal length.
Module, width and number of teeth series and specifications of synchronous toothed belt
Polyurethane synchronous belt with module m=4mm, width b=60mm and teeth number Z=100:
Polyacrylate synchronous belt 4 × 60 × 100
The synchronous toothed belt takes the center line of the strength layer as the pitch line, and the circumferential length of the pitch line is LpIs the nominal length. The distance between the corresponding points of two adjacent teeth along the pitch line is called circumferential pitch p, and the modulus m=p/π.Domestic synchronous toothed belt adopts module system.The mark of the belt is: module (mm) × width (mm) × number of teeth, that is, m × b × z.See the table above for the series of module, width and number of teeth and the corresponding specifications among them.
characteristic
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Compared with ordinary belt drive, ① the strength layer made of steel wire rope has little deformation after being loaded, the circumferential pitch of toothed belt is basically unchanged, there is no relative sliding between belt and pulley, and the transmission ratio is stable and accurate; ②The toothed belt is thin and light, which can be used in high speed situations. When driving, the linear speed can reach 40m/s, the transmission ratio can reach 10, and the transmission efficiency can reach 98%; ③Compact structure, good wear resistance; ④Due to the small pre tension, the bearing force is also small; ⑤The manufacturing and installation accuracy is very high, and strict center distance is required.
Application development
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Since the synchronous belt mainly relies on the positive pressure of the tooth surface to transmit force, its pulley size and center distance are smaller than those of V-belt and flat belt, and the maximum reduction ratio is only 1:10.Its transmission efficiency can reach 99.5%, belt speed can reach 50 m/s, transmission power can reach hundreds of kilowatts, positioning accuracy can reach 0.05 mm/300 mm, and it is oil resistant, moisture resistant, and does not need lubrication.
Therefore, the synchronous belt can not only be used to transmit motion and power, but also be used in the motion control system to position the mechanism.The early timing belt tooth shape is trapezoid.Since the 1980s, the circular arc tooth synchronous belt has been developed. It has more reasonable stress distribution and greater load bearing than the trapezoidal tooth synchronous belt.[2]
