Increasing the longitudinal parallelism of the original lathe The taper error of the machined part is due to the fact that the lathe saddle and the slide are not parallel to the centerline of the lathe spindle during movement. The daily qualification standard of the equipment stipulates the allowable error of the ordinary lathe. Since the parallelism tolerance and the inclination tolerance are the allowable values ​​on the radius, the taper produced by the machined part is twice the tolerance of the lathe.
Numerical control correction processing improves the vertical parallelism (theoretical value) of the machined parts and the original lathe tolerance as shown. Precautions during programming The direction of the tool can be determined by the principle of oblique line command processing. For example, when machining the correction of the small taper error at the left and right ends of the left end of the part, the direction of the NC correction machining is: vertical from left to right and horizontal from rear to front. , that is, the longitudinal displacement to the left is LSmm, and the lateral feed displacement is 0.005 mm. At this time, the screw clearance should be eliminated before the movement to start the oblique line command, that is, the direction of the lateral movement before the correction should be corrected and the direction of the large end should be reduced. Consistent. This eliminates the effects of errors caused by the screw gap when the screw is moved in the reverse direction.
When the large taper error at the left end of the left end is corrected, the longitudinal running direction is unchanged, and the lateral running direction is opposite. The above is the numerical control correction machining of the shaft parts, and the same is true for the correction of the curve of the hole parts.
Increasing the lateral parallelism of the original lathe The lateral parallelism error of the original lathe is caused by the parallelism error of the middle slide rail. Measures to Improve the Lateral Parallelism of Lathes For disc-type parts that require only the accuracy of the end-parallelism, the corrective processing measures are the same as increasing the longitudinal parallelism. The difference is: L is the lateral parallelism tolerance of the original lathe, and R is the lateral displacement length. Since the pulse equivalent of the lateral stepping motor is 0.01 mm, the longitudinal displacement of each step can increase or decrease the thickness of the one-side end face of the machined part by 0.01 mm, that is, correcting the parallelism between the machined end faces can only reduce the error to 0.02 mm. Therefore, the end face parallelism of the workpiece to be machined can be increased to an L2S times the tolerance within any length.
Precautions during programming The daily appraisal standard of the equipment stipulates that the slide running in the lathe can only be tilted from right to left. The working end face is convex and concave. The actual displacement track during the correction machining is: bcdefghi, which is the lateral displacement per RLmm. , the vertical shift of the right direction is 0.01mm. At this time, the clearance of each running screw should be eliminated first, and then the diagonal line is corrected to correct the machining path. The same reason is as described above. It is corrected that the direction of motion during processing is the same as the direction in which the lowest point of the concave surface is increased; and for the other corresponding end surface, the direction of motion is consistent with the direction in which the highest point of the convex surface is reduced. The processing order is first right and then left.
In order to eliminate the influence of the screw gap, the knife should first adopt the principle of first left and right. The turning tool is a double-edged combination. For the end face of the middle slide which is inclined from left to right, the direction is reversed, and the direction is constant to the left and the left is shifted. The machining order is first right and then left. The same applies to the end face correction processing of the hole parts. It is difficult to achieve satisfactory results simply because of the difficulty in measuring the flatness, especially for the parts of the narrow-hole structure of the inner hole.
Increasing the verticality of the machined part The verticality of the machined part is caused by the error in the centerline of the spindle when the slide is laterally displaced in the lathe. See the standard requirements for daily identification of equipment. The reason for improving the verticality of the machined parts is the reason for the verticality. It is known that the above error is for the center line of the lathe spindle. Due to the existence of the longitudinal parallelism error of the lathe, the workpiece is tapered, and the horizontal displacement of the slide is added. The time error will make the part's verticality error larger.
Since the verticality error is caused by two-way factors, it should be corrected step by step. A comparison of the trajectory curves is shown. It can be seen that the accuracy of the verticality is greatly improved compared with the correction before processing.
Precautions during programming 1) Direction of the cutter: In order to eliminate the influence of the screw clearance, the direction of motion before the correction should be corrected in the direction of the high point of the original trajectory. 2) Since the reference when finishing the car is the center line, the axial error should be corrected first (the same as before), and the radial error should be corrected after the detection.
In order to ensure the improvement of the verticality, the thickness can be reduced by 0.01mm or the lower limit of the size at the end face (except the maximum diameter section). Even if the end face is small and large, the axial length should be such that the right end is 0.01 from the left end. Mm, the specific size of the reduced size of 0.01 mm can be determined according to the assembly of the parts.
Other precautions for CNC correction machining 1) Since the correction machining is bound to cause cumbersome programming, it should be used only in the finishing and high precision requirements. 2) Correction should be based on the structural material of the part to be machined, and the amount of cutting should be correctly selected to minimize the movement resistance during machining, because the influence of the cutting force will reduce the accuracy of the control. 3) After the correction processing, the comprehensive error of a certain part of the lathe, the guide rail and the lead screw of the lathe is determined. In order to ensure the consistency of the size of the machined parts, a special positioning device should be provided to ensure the parts to be machined after being clamped. At the same coordinate position on the lathe.
The magnitude of the extension pulse equivalent is one of the important conditions for improving the geometric accuracy of turning. Generally, the pulse equivalent of the CNC lathe is: 0.005mm in the horizontal direction and 0.01mm in the longitudinal direction. If the pulse equivalent is reduced to 0.0025mm and 0.005mm, the geometric accuracy of the machined part can be more significantly improved.
The specific method is as follows: a pair of gear transmission transitions are added between the stepping motor and the longitudinal transverse screw of the lathe, and the transmission ratio i is 1:2, so that the pulse equivalent can be halved. The above correction processing is also true for the economical CNC milling machine (two coordinates of the control plane).
(Finish)
Freestanding Bath Shower Mixer
Free Standing Bath Mixers,Freestanding Bath Shower Mixer,Free Standing Bath Shower Mixer,Waterfall Freestanding Bath Taps
Kaiping City Yibiao Sanitary Ware Co., Ltd. , https://www.aolifaucets.com