Contact Us

TEL: +86-574-86159088
Fax: +86-574-86158328
E-mail: xuhong@cn-tianhui.com
Address: Hongxi Industrial Park No.12th ,Chunhu Town, Fenghua District  ,Ningbo ,Zhejiang Province,China 

Home > Knowledge > Content
Elimination of transmission gear clearance in CNC machining feed system
Nov 15, 2018

The transmission gear in the CNC machining machine feed system 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 machining accuracy. There are two common methods for eliminating the gap of the transmission gear by CNC machining machines.


Rigid adjustment method

The rigid adjustment method is an adjustment method that adjusts the back tooth gap without automatic compensation. Therefore, the tolerance of the gear and the tooth thickness of the gear should be strictly controlled, otherwise the flexibility of the transmission will be affected. This adjustment method has a relatively simple structure and a good transmission rigidity.

20181025175142_8021

(1) Eccentric shaft adjustment method


As shown in Fig. 6-10, the gear 1 is mounted on the eccentric bushing 2, and the adjustment of the eccentric bushing 2 can change the center distance between the gear 1 and the gear 3, thereby eliminating the gap.


(2) Axial gasket adjustment method


As shown in Fig. 6-11a), a pair of meshing spur gears can change gear 2 and gear 1 if their pitch diameter is made a small taper along the axial direction of the gear, changing the thickness of the washer 3. The axial relative position eliminates the flank clearance.


As shown in Fig. 6-11b), a spacer 2 is applied between the two thin bevel gears 3 and 4, and the thickness t of the spacer is changed, and the spirals of the foil gears 3 and 4 are misaligned, so that the thin plate gear 3 and 4 The left and right sides of the slot of the wide bevel gear 1 are respectively in close contact with each other, thereby eliminating the flank clearance.


20181025175200_6173

2. Flexible adjustment method


The flexible adjustment method is an adjustment method in which the backlash is still automatically compensated after adjustment. This method generally uses the pressure of the pressure spring to eliminate the flank clearance, and also maintains the gapless engagement in the case of the tooth thickness and the circumference of the gear, but the structure of the adjustment method is complicated. The size is large, the transmission stiffness is low, and the smoothness of the transmission is also poor.


(1) Axial compression spring adjustment method


As shown in Fig. 6-12, the two thin bevel gears 1 and 2 are sleeved on the shaft 6 with the key 4, and the axial pressure of the compression spring 3 is adjusted by the nut 5 so that the left and right tooth faces of the foil gears 1 and 2 are provided. The left and right flank faces of the wide bevel gear 7 are respectively in close contact with each other, thereby eliminating the flank clearance. The spring force needs to be adjusted properly, too loose to eliminate the gap, and too tight to accelerate the wear of the gear.


(2) Circumferential spring adjustment method


As shown in FIGS. 6-13, the two sheet gears 1 and 2 having the same number of teeth mesh with the other wide gear, and the gear 1 is sleeved on the gear 2 so as to be relatively rotatable. Each gear end face is uniformly provided with four threaded lugs 3 and 8, respectively, and the end face of the gear 1 has four through holes through which the lugs 8 can pass, and the springs 4 are respectively hooked on the adjusting screws 7 and 9 lugs 3 . Rotating the nuts 5 and 6 can adjust the pulling force of the spring 4, and the pulling force of the spring causes the sheet gears 1 and 2 to be displaced from each other, and the left and right tooth faces of the wide gear tooth groove are respectively pressed against each other to eliminate the flank clearance.


Previous: Cnc processing safety precautions

Next: CNC machining machine requirements for feed movement