The CNC program compensates for the machine’s backlash, precision turning.

With the rapid development of modern technology solutions, in order to meet the needs of high-precision parts processing, increasingly advanced precision CNC machining equipment has gradually replaced the traditional general work. However, the radius value of the arc structure during turning can often only be guaranteed by high-precision CNC machine tools, which has caused two problems: one is that the capital investment of precision CNC machine tools is too large, and the other is the backlash problem caused by the wear of the lead screw; the machine has been in operation for a long time. When turning the arc, the machine needs to constantly control the X and Z axes to perform trapezoidal interpolation after receiving the CNC “G02” or “G03” and “G03” instructions. The large backlash of the lead screw will greatly reduce the point control degree and the repeat positioning accuracy of the machine, which will ultimately lead to size shift and discrete instability of the workpiece quality in batch processing. In serious cases, safety problems may arise, such as safety problems. Puncture or tool collision. However, the maintenance and replacement of the lead screw will bring a lot of maintenance costs and time to the enterprise. Therefore, whether you use ordinary economical CNC machines or precision CNC machines, how to maximize the turning accuracy according to this. The amount of backlash of the lead screw has become the biggest problem. This article takes the groove of the valve stop clamp of a certain type of marine medium-speed diesel engine as an example, and uses an economical CNC machine to discuss the precision turning method that uses. CNC programs for machine backlash compensation.

1.Process Introduction

In order to ensure the processing quality of the product, the valve needs to be pre-machined, that is, rough machining using different equipment and materials, as follows:

1.1 Traditional economical CNC lathe (manual clamping)

1.1.1 Clamp the φ14mm rod (the processing allowance is reserved before this process), select the corresponding turning parameters according to the material, that is, the speed, feed, back cutting amount, use a special positioning sleeve (arc sleeve or angle sleeve can be used), and use the arc of the neck after rough turning as the positioning reference point, and quantitatively rotate the outer circle and the end face position of the disc to be clamped during fine turning, so as to form an accurate reference for the subsequent.

1.1 .2 Use the reverse tooth gripper to push the bottom surface of the plate to the required position, and manually lock the three-jaw chuck (if the four-jaw chuck is used, it is necessary to use the gauge to calibrate the rod body after clamping to ensure that the clamping reference point is correct, but because the rod body is still in the state of rough processing before this process, the correction is difficult and there is a certain deviation. Use the inner center / concave center to position the end of the rod (if there is a center hole at the end of the rod, it can be used directly), rotate the body of the 14mm diameter rod and set the drilling guide.

1.1.3 Rotate and clamp, clamp the 14mm diameter rod after turning, position it together with the rod end surface, move the center frame to the diameter change point, and at the same time return the distance between the drill tailstock to zero, and drill the center hole at the bottom of the plate.

1.1.4 Clamp the external cylindrical grinder and use the double center to grind the outer circle and the bottom surface of the plate (the grinding length when grinding the bottom should only exceed the clamping distance of the chuck. If the centerless grinder is used for this step, grind the rod body first). Then use the grinding rod body as a guide to machine the center hole of the bottom surface of the plate. This step is not required for manual clamping on an ordinary economical CNC machine. If the size problem is more serious, a grinding machine can be used to create it.

1.1.5 On ordinary lathes, the disc clamping method + auxiliary center frame is adopted, and the bottom surface of the disc is positioned. After manual clamping, the clamping grip is fixed and the center frame is fixed. Moves to a position as close to the end of the rod as possible (without affecting the feed). According to the chamfer angle of the end of the rod, the main cutting edge is rotated to the same angle as the chamfer angle, and the chamfer is positioned and. If the workpiece is hard or the surface contains a wear-resistant coating, it can be corrected by cutting. It is worth noting that although this step is a general operation, it is very important because the chamfer is processed . rough turning state before the correction process. After grinding, eccentricity and half size often occur (this is more obvious when processed on a centerless grinder. This is important).