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Elimination of Transmission Gear Clearance in CNC Machining Feed System

Elimination of Transmission Gear Clearance in CNC Machining Feed System

The transmission gear in the feed system of the CNC machining machine must eliminate the transmission gap between the meshing gears as much as possible, otherwise the movement will lag behind the command signal after each reverse of the feed system, affecting the processing accuracy (Accuracy). There are two common methods for CNC machining machine tools to eliminate transmission gear clearance.

Rigidity adjustment method

The rigidity adjustment method is an adjustment method in which the backlash cannot be automatically compensated after the adjustment. Therefore, the tolerance of the circumferential joint of the gear and the tooth thickness should be strictly controlled (otherwise, otherwise the flexibility of the transmission is affected). This adjustment method is relatively simple in structure and has good transmission rigidity.
(1) Eccentric shaft adjustment method
As shown in FIG. 610, the gear 1 is mounted on the eccentric bush 2. Adjusting the eccentric bush 2 can change the center distance between the gear 1 and the gear 3, thereby eliminating backlash. In numerical control processing, the control system sends out instructions to make the cutter perform various movements that meet the requirements, and expresses the processing of technical requirements and processing requirements such as the shape and size of the workpiece in the form of numbers and letters. It generally refers to the process of processing parts on CNC machine tools. In order to improve production automation, shorten programming time and reduce CNC machining costs, a series of advanced CNC machining technologies have also been developed and used in the aerospace industry.
(2) Axial gasket adjustment method
As shown in Figure 611a), a pair of meshing cylindrical gears can change the axial direction of the gear 2 and the gear 1 if their pitch circle diameter is made a small taper along the gear axis and the thickness of the gasket 3 is changed Relative position (position), thereby eliminating backlash. In numerical control processing, the control system sends out instructions to make the cutter perform various movements that meet the requirements, and expresses the processing of technical requirements and processing requirements such as the shape and size of the workpiece in the form of numbers and letters. It generally refers to the process of processing parts on CNC machine tools. In order to improve production automation, shorten programming time and reduce CNC machining costs, a series of advanced CNC machining technologies have also been developed and used in the aerospace industry.
As shown in Figure 611b), add a shim 2 between the two helical gears 3 and 4 to change the thickness t of the shim, and the spirals of the shim gears 3 and 4 will be misaligned, so that the spur gears 3 and 4 are respectively The left and right sides of the tooth groove of the wide helical gear 1 are closely attached to each other, thereby eliminating backlash.

 Flexible adjustment method

The flexible adjustment method is an adjustment method in which the backlash can be automatically compensated after adjustment. This method generally adopts the adjustment of the pressure of the spring (Spring) to eliminate the backlash of the tooth, and can maintain the gapless engagement even when the tooth thickness and the circumferential pitch of the gear change, but the structure of this adjustment method is more Complex, large axial size, low transmission rigidity, and poor transmission stability.
(1) Axial compression spring adjustment method
As shown in FIG. 612, the two thin helical gears 1 and 2 are sleeved on the shaft 6 with the key 4, and the nut 5 is used to adjust the axial pressure of the compression spring (Spring) 3, so that the left and right teeth of the thin gear 1 and 2 The surfaces are in close contact with the left and right tooth surfaces of the tooth groove of the wide helical gear 7, respectively, thereby eliminating backlash. The spring force needs to be adjusted properly, too loose can not eliminate the gap, too tight will accelerate the wear of the gear (a basic type of component failure).
(2) Spring adjustment method
As shown in FIG. 613, the two thin gears 1 and 2 having the same number of teeth mesh with another wide gear, and the gear 1 can be relatively rotated on the gear 2 without a sleeve. CNC machining generally CNC machining usually refers to computer digitally controlled precision machining, CNC machining lathe, CNC machining milling machine, CNC machining boring and milling machine, etc. The feed route for finishing is basically carried out along the contour of its parts. Therefore, the work of determining the feed route is to determine the feed route for rough machining and empty stroke. The end faces of each gear are uniformly (jūn yún) equipped with four thread lugs 3 and 8, the end face of the gear 1 also has four through holes, the lug 8 can pass through, and the spring 4 is hooked to the adjusting screw 7 and 9 on lug 3. Turning the nuts 5 and 6 can adjust the pulling force of the spring (Spring) 4, the pulling force of the spring (Spring) causes the thin gears 1 and 2 to be misaligned with each other, and they are in close contact with the left and right tooth surfaces of the wide gear tooth slot to eliminate backlash .

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