The rack-and-pinion transmission system is widely used in large-scale machine tools with large strokes due to its advantages of large transmission ratio, high speed, and high rigidity. However, for the rack and pinion of the CNC feed system, in addition to requiring high motion accuracy, it is also necessary to eliminate the transmission gap between the mating rack and pinion. Otherwise, each time the machine tool feed system reverses, a backlash will occur. , Has a great influence on the machining accuracy.
How do we eliminate the gap in the DSKR rack drive?
Find ways to eliminate or compensate to improve machining accuracy. Traditional anti-backlash is a rigid or flexible mechanical anti-backlash method. The mechanical anti-backlash method will increase the complexity of the mechanical structure, and the reliability of mechanical anti-backlash will be poor.
Backlash compensation needs to be measured, especially for CNC machine tools with semi-closed loop control. It is necessary to pay attention to the factors that cause backlash and use the backlash compensation function to compensate for the feed transmission chain of the machine tool. At the same time, the roller screw has a pitch error, and the backlash at each position is different.
The position of the gear should not be fixed, it should be made adjustable, such as an eccentric bearing seat structure or a long hole, fine-tuning the meshing gap of the rack and pinion, The control system must set the backlash compensation command to adjust the transmission gap after the gear is reversed. Adjust the number of servo motor pulses according to the actual gap value.
The automatic message device of the rack and pinion transmission, the machine base, and the driving beam are broad in mind—the driving beam slides along the linear guide rail set on the machine base. At the end of the driving beam, a servo motor and a transmission gear connected with the servo motor are set. The racks are arranged on the machine tool base mesh, the end of the driving beam is provided with a mounting plate, and a rotating shaft frame and a bracket are arranged on the mounting plate. The rotating shaft frame and the reducer mounting frame are connected by the rotating shaft, and the reducer is installed A protruding ear plate is provided on the opposite side of the frame, a bolt passes through the hole on the ear plate and is threadedly connected with the bracket, and a disc spring group is sleeved between the bolt head and the ear plate.
When the transmission load is small, the double-piece thin gear staggered tooth adjustment method can be used to close the tooth groove surfaces of the left and right sides of the rack respectively to eliminate the side clearance. When the transmission load is large, the structure of a double-thick gear transmission can be adopted.
The dual-drive feed system is adopted; that is, the servo control is used to achieve anti-backlash. Although the dual-drive system overcomes the shortcomings of mechanical anti-backlash, in the high-precision and high-speed gear transmission system, manufacturing and assembly errors have a great influence on transmission accuracy.
Detection of the correct meshing of the rack and pinion
That is to detect the backlash of the rack and pinion, the detection method is to use two dial gauges, one of which is fixed on the base surface of the bed, and the meter head measures the side of the motor seat; the other dial gauge fixes the base surface of the bed Above, the pitch diameter position of the gear on the meter head side. Move the gear in one direction. After the dial indicator is zeroed, rotate the gear in the opposite direction. The difference between the changes in the two dial indicators is the backlash, which is required to be less than 0.125 mm in the example.
For high-speed and high-precision large-stroke CNC machine tools, the coloring method is used to check the contact of the rack and pinion to ensure the correct meshing of the rack and pinion.
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