# Method of sprocket design and processing

Sprocket Design and Machining

1. Design of sprocket: For the sprocket of the standard chain with a pitch of 12.7-38.1, various manufacturers have adopted

Standard hobs are produced on gear hobbing machines.When processing, the user only needs to provide the number of sprocket teeth, pitch and roller diameter to produce.The sprocket is designed according to GBl244-85.On the basis of the necessary data provided by the user, the non-standard sprocket should be calculated as follows: the diameter of the index circle: d points=P/sin180 degrees/Z=P·K, P-pitch, K-tooth coefficient can be found in the table.

The tip circle can be determined according to the drawing, or 0.85-0.95 times the roller diameter can be added on the basis of the index circle.The above data are important parameters for sprocket design.

certainly.The sprocket design of the special chain is different from this, and it needs to be calculated according to the sprocket formula in the relevant manual.

2,SprocketTooth machining The most important part of sprocket machining is tooth machining.As mentioned earlier, most of the sprockets of a standard chain are machined with a hob on a gear hobbing machine.The processing methods of large-sized and non-standard sprockets are different due to the limitation of equipment, tools, and quantity.At present, the most widely used are still the forming method milling sprocket and the Fan Cheng method hobbing sprocket.The tooth shape of the roller chain sprocket milling cutter is designed according to the shape of the sprocket tooth groove.In order to save tools, the tools are usually designed in groups according to the number of sprocket teeth, and the tooth shape of each group is designed according to the calculated number of teeth. The calculated number of teeth can be calculated as follows:

Zc=2Zl·Z2/Zl+Z2 In the formula: the minimum number of teeth in the same group of Z2, and the maximum number of teeth in the same group of Z1. (2) The method of machining the tooth shape with the forming knife: It is a common processing method to use a forming disc milling cutter or a finger-shaped forming milling cutter to process the tooth groove on a horizontal or vertical milling machine equipped with an indexing head.Suitable for batch processing of large pitch sprockets. (3) The method of machining the tooth shape with a saddle milling cutter: using a saddle milling cutter to simultaneously mill two symmetrical teeth on two adjacent tooth slots on a horizontal milling machine equipped with an indexing head is the current toothed sprocket. Commonly used processing methods.Suitable for medium and small batch production. (38.1) The method of hobbing and machining the tooth shape: the tooth groove is machined with a hob on the hobbing machine, which is suitable for the processing of the sprocket with the standard sprocket pitch P=4 or less.high productivity.Good precision. (5) Gear shaping method: use a disc gear shaping cutter or a comb cutter to process the sprocket slot on the gear shaping machine.Suitable for single piece and small batch production. (6) For larger sprockets, scribing and drilling can also be used for planing or plunging, which is another processing method. Obviously, this method is relatively backward, but large sprockets are limited by processing equipment and quantity. This method can also be used. (XNUMX) Recently, some units have solved the problem of processing large sprockets by using a copying machine to cut the tooth shape, which is very creative.

The processing technology of profile cutting tooth shape is as follows:

A. First put the machined sprocket on the indexing plate, and the sprocket is fixed by the pressure plate and screw bolt on the mandrel.The ring gear surface is required to be flat.

B. At any position on the processed gear ring, cut the tooth shape whose depth is less than 4-5mm of the designed tooth shape according to the tooth shape of the template, and then measure the verticality of the ruler surface with a square ruler.

C. Measure the distance H between the depth of the ruler that has been cut and the edge of the shaft hole that has been machined.

D. The calculation also requires the processing depth B. B=Measurement dimension - the distance between the edge of the shaft hole and the edge of the diameter of the index circle.

E. Adjust the size of the connecting rod of the cutting machine, that is, extend a deepening amount on the basis of the original size, and then cut according to the template after adjustment.

F. After cutting a tooth, use the indexing plate to index.After cutting three teeth, measure the ipsilateral parity distance across the teeth.After cutting the fourth tooth, move one tooth on the same side to measure in the same way, and so on.

G. If there is a large difference between the measured dimensions or the width of the tooth top is large, the wider side can be cut off and welded on the other tooth surface for trimming.

H. After cutting, the tooth surface is polished with a hand grinding wheel and then surface quenched.

L. Perform other processing.

3. Method of adding chip and flange sprockets

(1) Processing of chip sprockets: The chip sprockets are generally cut from steel plates and then machined, which can improve the utilization rate of their materials.Small-sized sprockets are mostly, standard sprockets are the majority. After turning, they are processed on a gear hobbing machine, and several pieces can be processed at one time.

(2) Flanged sprocket processing: There are two methods for flanged sprocket processing;

A. Overall machining, that is, machining the tooth shape after cutting the bar.This method has low material utilization and high cost.

B. Welding processing. Obviously, this method has higher material utilization and lower wood yield than overall processing.The specific processing method is as follows: the outer diameter and the shaft hole can be roughly machined after cutting the ring gear part with a steel plate, and a welding groove is left on one side of the shaft hole.Then the flange part of the bar car is used to form a convex shape, the ring gear part and the flange part are joined together, and the finished product is welded on both sides, and the welding part is arced.After machining, select the appropriate method to process the tooth shape.

weldingSprocketIt is best to use a low hydrogen electrode for the electrode to prevent the 45 steel from cracking due to the welding junction.For large and important sprockets, it is best to preheat the electrode before welding, the preheating temperature is 150-200, and the time is 1-2 hours.

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