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At the same time, workers are labor intensive, so when they are mass-produced in batches, hydraulic profiling lathes are often used to process, which is not only easy to achieve semi-automation of turning, but also reduces labor intensity and productivity. In the processing of profiling lathe, the design of the sampled shaft is good or bad, and the use of it does not directly affect the precision of the workpiece. Therefore, it is extremely important to use a profiling lathe to machine shaft parts and design a good shaft.
1 axis design method Before designing the sample axis, you should carefully read the original workpiece part drawing to accurately grasp the various dimensions, tolerance requirements and technical requirements, so that you can know what you are doing.
The working principle of profiling is generally that the profiling pin moves along the contour of the sample axis, and the movement of the sliding valve is driven by the swing of the lever, and then the movement of the sliding body and the saddle is controlled to be combined so that the tool can be shaped as a shaft. The movement is consistent, and the turning is done on the workpiece. Therefore, it is necessary to design a high-quality sample shaft to process a workpiece that meets the accuracy requirements.
1. Determination of the basic dimensions of the 1-axis Axis The basic dimensions of the sample axis are determined by the average size of the workpiece. The following formula dy = ds + di 2; ly = ls + di 2 where: dy - the radial basic dimension of the sample axis ;ds-sample axis radial maximum dimension; di-sample axis radial minimum dimension ly-sample axis radial basic dimension; ls-sample axis radial maximum dimension; li-sample axis axial minimum dimension as in the drawing radial The dimensions are 25 - 0. 15 - 0. 35, the basic dimensions of the sample axis are dy = < (25 - 0. 15) + (25 - 0. 35) > / 2 = 24. 75. The axial dimension of the workpiece is 27 0 - 0. 2, the basic size of the sample axis is ly = < 27 + (27 - 0. 2) > / 2 = 26. 9.
1. Determination of the basic dimensional deviation of the 2 sample axis The radial deviation of the sample axis is generally 1 / 5 ~ 1 / 8 of the workpiece tolerance. The axial deviation is generally 1 / 3 ~ 1 / 5. The workpiece tolerance is ei y = - es c - ei ck (radial) ; es y ei y = ± es c - ei ck × 1 2 (axial) where ei y - the sub-axis deviation; es y - the deviation on the axis; es c - Deviation on the workpiece; ei c - deviation under the workpiece; k - precision coefficient, taking 5 to 8 in the radial direction and 3 to 5 in the axial direction.
In the drawing, the radial dimension of the workpiece is 25 - 0.15 - 0. 35, and the deviation of the sample axis is ei y = - (- 0. 15 + 0. 35) / 6 = - 0. 033 (k takes 6) Therefore, the dimension of the sample axis should be 24.75 0 - 0. 35 °. The axial dimension of the workpiece is 27°-0.2, and the deviation of the sample axis is es y ei y =±0 + 0. 2 5×1 2 =±0. 02(k takes 5), so the dimension of the sample axis It should be 26. 9±0. 02.
1. 3 Un-tolerance of the workpiece and the size of the closed ring In the sample axis, the size of the workpiece is not tolerated. The tolerance is also marked in the sample axis. The tolerance in the workpiece is selected according to the free tolerance js14. The tolerance is selected according to the free tolerance h14.
In the drawing, the axial dimension 50 of the workpiece is an unfilled tolerance dimension, which is selected as ±0.11 according to the free tolerance JS14, and the basic dimension in the sample axis is (50.31 + 49.69) / 2 = 50, the deviation is ± = ±0.
0775 (k takes 4), so the sample axis should be marked as 50±0. 0775. The radial dimension 35 of the workpiece is an unfilled tolerance dimension, which is selected as 0 - 0.62 according to the free tolerance h14, then the basic in the sample axis The dimensions are (35 + 34. 38) / 2 = 34. 69 deviation is - (0 + 0. 62) / 6 (k takes 6), so the sample axis should be marked as 34. 69 0 - 0. 1°.
The size of the closed ring in the workpiece is also marked in the sample axis, and its basic size is still the average size after conversion. The tolerance requirements can be given by itself. The axial dimension of the drawing shaft is 15 ± 0.1, which is the size of the closed ring in the workpiece. Figure axis design legend 1. 4 arc, chamfer determination of the arc in the workpiece, chamfering, in the design of the sample axis should be corrected according to the specific circumstances after the calculation. The chamfer should be converted after the basic size is determined. The circular arc is corrected according to the radius of the arc of the contact pin and the tip.
1. Determination of the size of the boring tool and the retracting tool in the 5-axis. The size of the boring portion in the front part of the sample axis is generally to ensure the shape of the head of the workpiece (such as chamfering). When designing this part, the contoured rotary tool holder should generally avoid interference with the tailstock and the tip. The length is generally 20mm-30mm. The radial dimension should be determined according to the chamfer of the last end of the sample axis. The rear part of the sample shaft should also be left with a straight section of 20-30 mm, which is used as the cut-out amount and retraction.
1. Other issues that should be noted in the design of 6-axis shafts (1) It should be noted that the angles of the cones that can be turned by different types of hydraulic copying lathes are also different. For example, the range of cones that can be turned by the CE7120 machine tool is + 90 ° ~ - 30 °.
(2) In order to prolong the service life, the sample shaft should be surface hardened, the profile should be quenched HRC42, and the profile roughness is 0. 8.
(3) The radial runout of each polishing surface facing the center line is not greater than 0. 01mm, the center hole at both ends shall be thermally polished to 0. 4.
Proper use of 2-axis on the profiling lathe After designing a precise sample axis according to the above method, the profiling lathe can be used to process the shaft parts. In the process, except for the machine tool itself, the tool, etc. In addition to affecting the machining accuracy of the workpiece, the operator may also cause errors in the machining of the workpiece due to improper use and storage of the sample shaft. Generally pay attention to the following aspects: (1) The expansion of the circular arc surface of the sample shaft can cause the radius of the circular arc of the workpiece to be enlarged, and the sample shaft should be ground or replaced.
(2) If the axial movement of the sample shaft can cause the axial dimension of the workpiece to be long and short, the sample shaft should be adjusted and fixed.
(3) The cone of the center hole of the sample shaft is bumped, causing the sample shaft to tilt, which will cause the outer cone to be out of tolerance. The sample shaft should be repaired or replaced and re-adjusted.
(4) When the sample axis is often placed horizontally during storage, the dimensional accuracy of the workpiece should be placed vertically or hanged.
(5) Copy turning is only suitable for rough or semi-finished cars.
(Finish)
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