The transmission gear in the feed system of the CNC machining machine tool must eliminate the transmission gap between the meshing gears as much as possible, otherwise the movement will lag behind the command signal after each reversal of the feed system, which will affect the processing accuracy (Accuracy). There are the following two common methods for CNC machining machine tools to eliminate the transmission gear gap.
1. Rigidity adjustment method
The rigid adjustment method is an adjustment method in which the side clearance of the tooth cannot be automatically compensated after adjustment. Therefore, the pitch tolerance and tooth thickness of the gear must be strictly controlled, otherwise the flexibility of the transmission will be affected. This adjustment method has a relatively simple structure and a better transmission rigidity.
- (1) Eccentric shaft adjustment method:As shown in Figure 610, the gear 1 is mounted on the eccentric sleeve 2. Adjusting the eccentric sleeve 2 can change the center distance between the gear 1 and the gear 3, thereby eliminating the gap. In the numerical control processing, the control system issues instructions to make the tool perform various movements that meet the requirements, and the shape and size of the workpiece are expressed in the form of numbers and letters, and the processing required by the processing technology. It generally refers to the process of processing parts on CNC machine tools. In order to improve the degree of production automation, shorten the programming time and reduce the cost of CNC machining, a series of advanced CNC machining technologies have been developed and used in the aerospace industry.
- (2) Axial gasket adjustment method:As shown in Figure 611a), if the pitch diameter of a pair of meshing cylindrical gears is made into a smaller taper along the gear axis, and the thickness of the gasket 3 is changed, the axial direction of the gear 2 and the gear 1 can be changed. Relative position (position), thereby eliminating the tooth flank clearance. In the numerical control processing, the control system issues instructions to make the tool perform various movements that meet the requirements, and the shape and size of the workpiece are expressed in the form of numbers and letters, and the processing required by the processing technology. It generally refers to the process of processing parts on CNC machine tools. In order to improve the degree of production automation, shorten the programming time and reduce the cost of CNC machining, a series of advanced CNC machining technologies have been developed and used in the aerospace industry.
As shown in Figure 611b), add a shim 2 between the two thin helical gears 3 and 4, change the thickness t of the shim, and the helix of the thin gears 3 and 4 will be misaligned, so that the thin gears 3 and 4 are respectively The left and right side surfaces of the tooth groove of the wide helical gear 1 are in close contact with each other, thereby eliminating the side clearance of the tooth.
2. Flexible adjustment method
The flexible adjustment method is an adjustment method in which the tooth flank gap can still be automatically compensated after adjustment. This method generally adopts adjusting the pressure of the pressure spring (Spring) to eliminate the tooth side clearance, and in the case of changes in the tooth thickness and circumferential section of the gear, it can also maintain a gapless meshing, but the structure of this adjustment method is relatively more. Complex, large axial size, low transmission rigidity, and poor transmission stability.
(1) Axial compression spring adjustment method
As shown in Figure 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 spring 3 to make the left and right teeth of the thin gears 1 and 2 The left and right tooth surfaces of the tooth slots of the wide helical gear 7 are in close contact with each other so as to eliminate the 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) Circumferential spring (Spring) adjustment method
As shown in Figure 613, two thin gears 1 and 2 with the same number of teeth mesh with another wide gear, and gear 1 is idler on gear 2 and can rotate relatively. CNC machining General CNC machining usually refers to computer digital control precision machining, CNC machining lathe, CNC machining milling machine, CNC machining boring and milling machine, etc. The feed route of finishing is basically carried out along the part contour sequence. Therefore, the focus of determining the feed route is to determine the feed route of rough machining and idle stroke. Each gear end face is uniformly (jūn yún) equipped with four threaded lugs 3 and 8, there are four through holes on the end face of the gear 1, the lugs 8 can pass through, and the spring 4 is hooked on the adjusting screw respectively. 7 and 9 lugs 3 on. Turning the nuts 5 and 6 can adjust the tension of the spring (Spring) 4. The tension of the spring (Spring) makes the sheet gears 1 and 2 misaligned with each other, and they are attached to the left and right tooth surfaces of the wide gear slot respectively to eliminate the tooth backlash. .