Device composition.
Table 1 The precision and surface roughness that can be achieved by broaching typical profiles. Surface finish precision Machining surface condition Roughness Round hole keyway Spline hole Gear tooth profile Accuracy grade 7~ 910 General grade 7-7——8 General surface roughness (key side) 6 (tooth side) 6 (tooth surface) accuracy grade 6 ~ 76 precision grade 6-7 - 7 surface roughness 1. 1.6 special degree Ra (key side) (tooth surface) (tooth surface) remarks broach The tail tooth belt adopts the process equipment used for shaping the whole belt calender ring detection knife blade broach as shown, mainly by the main body part mounted on the lathe main shaft and the front bracket 7 and the floating on the rear bracket 20 The role of the bracket is to support the bearing and compensate the end face of the pair of 1994-2012 ChinaAcademicJo leg aElec her ic brewed is 0 0 A1 is the support e workpiece / compensation workpiece c end face to t 0 foreword in the mechanical manufacturing and repair work In order to improve the productivity and accuracy of the spline hole, the round hole and the key groove of the workpiece to be processed, a broaching process can be employed. The machine repair shop without broaching can be modified by various models (old, waste) ordinary lathes, as long as a set of fixtures can be added, the method is simple, easy to manufacture, and can fully meet the quality requirements. Moreover, the tooling is removed, and the performance of the original lathe can be restored.
1 Advantages of broaching Compared with other cutting methods, broaching has the following characteristics: the broach has a large number of teeth at the same time, the cutting edge is long, and the rough, semi-finishing and finishing can be completed at one time, so the production efficiency is high.
High machining accuracy and surface roughness are obtained.
The broach is highly durable. Due to the low broaching speed and the use of a good cooling lubricant, the tool wear is slow.
The broach is standard and easy to purchase. In mass production, broaching can be performed for the processing of spline holes and keyways with certain precision.
The wide range of broaching is especially suitable for the machining of profiled cross-section holes that cannot be processed or processed by other machining methods. The common hole shape is as shown: the accuracy and surface roughness of the common hole shape diagram for machining circular, spline, and single-key (multi-key) grooves are shown in Table 1.
2 Modification principle and method To change various lathes into broaching machines, the following two problems must be solved: changing the rotary motion of the lathe into a linear reciprocating motion. (2) The lathe spindle is only output torque without being subjected to tensile force.
Thrust plate 6 sleeve 7 front bracket 8. lead screw 9. guide rod 10. guide arm 11. key 14. broach chuck 16 spring 17 spherical support 18. spherical ring 19. positioning sleeve 20. rear bracket process device And the structure diagram of the clamp is shown: the nut 1 is screwed to the lathe main shaft, and the nuts 4 and 1 are press-fitted, and then tightened by the screw 2. By the engagement of the nut 4 with the drive screw 8, the rotary motion of the lathe spindle can be changed into the axial movement of the screw 8. Two guide rods 9 are fixed to the front brackets 7 and 20, and the guide arms 10 are fixed to the lead screw 8 with keys and nuts. This structure ensures that when the spindle of the lathe is positive and reverse, the drive screw does not rotate and can only reciprocate axially.
The thrust bearing 3, the thrust plate 5, the sleeve 6, and the front bracket 7 fixed to the lathe constitute an unloading device that causes the lathe main shaft to output only torque without receiving tensile force. During broaching, the axial pulling force of the drive screw is absorbed by the above device.
3 Clamping clamps The specific floating device consists of the positioning sleeve 19, the spherical bearing 17 and the spherical ring 18, the spring 16 and the nut 15, and is mounted with a vertical error of the fixed hole axis to prevent the deflection of the hole or even Break the broach.
4 The problem to be noted in the modification is that the full tension is received by the front bracket 7, and the parallelism of the end faces of the sleeve 6 is required to be in the range of 0.01/100 mm.
In order to increase the rigidity of the front bracket, the contact portion between the bottom surface of the bracket and the surface of the guide rail needs to be scraped to reach 1215 points / 2525 mm. In order to make the end surface of the sleeve and the front bracket good, the verticality of the bottom surface and the end surface of the front bracket is 0.03/300 mm. The front and rear brackets are to be increased in strength and rigidity, and a fastening plate (not shown) is provided between the guide rails.
5 Operation method The broach chuck is screwed to the drive screw and locked with a nut. During broaching, the broach is placed in the broach chuck through the part hole, and the end face of the workpiece is pressed against the positioning sleeve, the coolant is opened, the nozzle is aligned with the cutting edge of the broach, and the start button is operated, the spindle is positive Turn, the drive screw drives the broach to move to the left for broaching. After the broaching is finished, the machine tool is reversed again, so that the broach is quickly returned to the original position to complete a cycle.
6 The broach size of the broaching machine of various lathes depends on the power of the spindle motor of the lathe, the material of the nut 4 and the driving screw and the size of the inner hole of the spindle (because the screw needs to pass through the inner hole).
The transmission accuracy of the lead screw and the nut is not too high. The transmission pair is mainly subjected to tensile force, so the strength calculation is required. For example, the nut material is made of high-strength ductile iron, and the screw material is 40. After forging, it is normalized. After the strength calculation, the allowable pulling force of the nut screw drive pair can be as shown in Table 2: Table 2 Lathe lathe for broaching machine model spindle bore diameter / mm screw OD / mm allowable pull / kN 7 Conclusion General enterprises need to purchase a new broach separately for more funds, the cost of this technology is about 10,000 yuan And can be modified with old equipment, expanding the processing range, and has great promotion value.
Changhe research direction (field): mainly engaged in cold-working manufacturing technology of rolling equipment and sheet shearing equipment, familiar with the performance, transmission principle and structure of various cold-working machine tools, and designing special tooling on ordinary machine tools to realize long and deep holes. The processing of large-size threads and irregular surfaces has rich practical experience. In the technical project of the maintenance and transformation of the machine tool in this unit, there is certain experience in the maintenance and repair of cold processing equipment. At present, the focus is on the manufacture of various types of transmission parts, machine tool transformation and mold finishing technology. Contact number: 0531 - Received time: 2003-07- (Continued from page 152) If the D error exceeds a certain value, it will cause assembly difficulties. Therefore, when grinding the small diameter, the center requirement of the grinding wheel dresser and the center of the center should be within the appropriate range to ensure the interchangeability of the assembly. Since the large-diameter centering method has been used in the past, the existing spline grinding machine is for grinding the key side, and therefore, the grinding wheel dressing mechanism cannot meet the grinding diameter requirement. In order to utilize existing equipment resources, a finishing mechanism as shown is designed. When using, adjust the top position of the machine according to the length of the mandrel, install the special dressing mechanism on the top, adjust the position of the diamond pen with the correction sleeve, generally use the light transmission method to proof the extension length, or use the feeler gauge to check, but pay attention to the design. A certain size should be added to the proofreading set. After confirming that the protruding length of the diamond pen is appropriate, tighten the screw, remove the proof sleeve, and turn the crankshaft by hand to rotate the mandrel and the diamond pen on the top of the machine tool to trim the working circular arc surface of the grinding wheel.
It can be seen from the foregoing that when the center of the diamond pen does not coincide with the center of the tip, an interference region D is generated at both ends of the arc of the workpiece to affect the interchangeability of the assembly. Therefore, the working radius of the wheel is adjusted when the grinding wheel is finished. Slightly smaller than the basic radius of the workpiece, (due to the manufacturing error, the diamond pen center is difficult to do absolutely coincide with the tip) so that the processed diameter is as close as possible to the lower deviation, so that the interchangeability can be well ensured.
3 Spline shaft detection The splined part of the small-diameter centering rectangular spline shaft that has been machined must also meet the drawing requirements to ensure the interchangeability of the assembly, so it must be tested. Generally, the dimensions of the large diameter, the small diameter, the key width, the coaxiality of the size and diameter, and the position of the key side are detected. Generally, there are two methods: single-item detection method: the actual size and shape position error of each individual element are measured by the measurement method, and the two are combined to determine whether each requirement exceeds the specified maximum boundary, and whether the mutual influence of the assembly is affected. Transmutation.
Comprehensive test method: use a spline integrated ring gauge with a shape corresponding to the spline to be judged to determine whether each element exceeds the specified maximum limit boundary, and use the stop gauge of each individual element (other gauges such as the outer diameter micrometer can also be used) The method is measured to determine whether each individual element exceeds the specified minimum physical size.
From the current test conditions and the need of production quantity, it is difficult to use the single item test method, and the test cost is high. The comprehensive test method is more convenient, and it is easy to ensure assembly interchangeability and has obvious economic effects. Generally, the spline integrated ring gauge test shall be deemed to be qualified under the action of its own weight or a suitable fixed working load (which shall be indicated on the gauge) and can pass smoothly over the entire length of the spline to be tested.
The detection of the coaxiality of other items such as the small diameter and the bearing positions at both ends is the same as the commonly used detection method, and will not be described here.
Received time: 2003-04-
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