Method for generating and machining spiral internal gear by using theoretical error-free finger-shaped cutter
Technical Field
The invention relates to the technical field of gear machining, in particular to a method for machining a spiral internal gear by utilizing a finger-shaped cutter without theoretical error.
Background
At present, methods for cutting and machining spiral internal gears at home and abroad mainly comprise two types, namely generating methods and forming methods.
The generating method comprises a gear shaping process and a powerful gear scraping process:
the helical inner gear shaping is a traditional processing technology, has low efficiency and is far from meeting the requirement of mass production. In addition, the machining process of the spiral internal gear is complex, a corresponding special spiral guide rail is additionally arranged on a common gear shaper, a special bevel gear shaper cutter needs to be customized, and the cost is quite high. In addition, the gear shaping cutting principle is influenced by the whole process system such as a machine tool, a cutter, clamping and the like, the machining precision requirement of a gear of 7 grade or above cannot be completely met, the inserted inner helical gear cannot be ground when the diameter of the inserted inner helical gear is small, errors exist between the inserted inner helical gear and the ground outer helical angle, and noise, abrasion and the like can be caused by the operation after meshing.
The powerful gear scraping is based on the principle that the meshing tooth surfaces of staggered shaft helical gears slide relatively, a cutting mode that rolling and gear shaping are integrated is adopted to process cylindrical gears with inner teeth and outer teeth, in the gear cutting process, a gear cutting tool is equivalent to a hob and a gear shaping tool, the cutting mode is that a workpiece and the tool rotate continuously, and hobbing and gear shaping movement are combined to cut the gears. Compared with the gear shaping, the single piece processing time of the process is greatly improved in production efficiency. However, due to the limitation of the cutting principle, the cutter is seriously worn, the cutter needs to be frequently changed, adjusted and detected, the machining precision of the cutter is similar to that of gear shaping, the current cutter is limited to small-batch production, and the precision needs to be improved.
The forming method adopts a broaching process, the broaching process has higher efficiency than the gear shaping process, but the broaching is a forming cutting principle, the tooth pitch accumulation and the tooth profile shape precision of a part are closely related to the precision of a broaching tool, and the direct reflection is close to 1: 1. The tooth pitch accumulation, the tooth profile shape, the spiral line error and the like which are key elements of the gear precision generally cannot be lower than 7 grades in hot pre-processing, so that the process has higher requirements on a machine tool and a broach. In addition, the defect that the broaching is influenced by the vibration caused by the change of the number of the working teeth at the same time so as to influence the cutting precision is solved, and the development difficulty of the high-precision helical internal gear broaching tool is very high. The spiral broaching process is relatively mature in the automobile industry strong country, but the process has extremely strict requirements on the precision of a broaching tool, the structure of the tool is complex, and the manufacturing difficulty is high.
Disclosure of Invention
The invention aims to overcome the defects of the technology and provide a novel method for machining a spiral internal gear, which has high machining efficiency and precision and is convenient to operate.
The invention adopts the following technical scheme:
a method for generating and processing a spiral internal gear by using a finger-shaped cutter without theoretical error is characterized by comprising the following specific steps:
s1, according to the tooth profile of the spiral internal gear to be machined, obtaining a spiral surface and a meshing surface formed by the tooth profile of the end surface of the spiral internal gear, and obtaining the tooth profile of a cutter without theoretical error for machining the spiral internal gear according to the tooth profile.
S2, the axis of the finger-shaped cutter is perpendicular to the axis of the processed spiral internal gear, and the cutter rotates around the axis of the cutter to finish the cutting motion of the tooth socket.
S3, the finger-shaped cutter moves along the direction parallel to the axis of the processed spiral internal gear, and the processed spiral internal gear rotates around the axis of the processed spiral internal gear to form a spiral angle of a spiral internal gear tooth groove.
S4, after the finger-shaped cutter finishes primary tooth groove cutting, the cutter stops moving along the direction parallel to the axis of the processed spiral internal gear, and the processed spiral internal gear rotates around the axis thereof for certain graduation.
S5, repeating S2-S4.
Further, in S3, the instantaneous rotation angle of the relative spiral motion of the spiral ring gear and the finger cutter to be processed is kept equal to the theoretical pitch helix angle of the spiral ring gear.
Further, another processing method in S3 is as follows: the finger-shaped cutter moves along the direction parallel to the axis of the processed spiral internal gear, and simultaneously, the cutter axis rotates around the axis of the processed spiral internal gear.
Further, the instantaneous rotation angle of the relative spiral motion of the finger-shaped cutter and the processed spiral internal gear is kept equal to the theoretical tooth space spiral angle of the spiral internal gear.
Further, after completion of S4, the finger cutter moves in the opposite direction parallel to the axis of the helical gear to be machined, and performs the next helical gear tooth groove cutting.
Further, the finger cutter is one or a plurality of finger cutters arranged along the same circumference.
The invention has the beneficial effects that:
(1) in the processing method provided by the invention, the finger-shaped cutter rotates around the axis of the finger-shaped cutter and performs spiral motion relative to the axis of the workpiece, so that the revolution surface of the finger-shaped cutter and the spiral tooth surface of a processed spiral internal gear are mutually enveloped, and the method belongs to a variation of a generating method, so that compared with a forming method, the processing precision is high; compared with a common generating method, the method can simultaneously process a plurality of tooth sockets, the processing efficiency is obviously improved, the abrasion of the finger-shaped cutter can be controlled, and the cutter does not need to be frequently replaced.
(2) The method provided by the invention can not only mill the spiral internal gear, but also conveniently realize grinding, and can finish the whole process from rough machining, semi-finish machining to finish machining on the spiral internal gear on the same set of equipment, thereby meeting the requirement of higher-level machining precision.
(3) In the processing method provided by the invention, the axis of the finger-shaped cutter is always vertical to the axis of the processed spiral internal gear, and the main motion and the feed motion in the whole milling process can be easily controlled, so that the machine tool adopting the processing method provided by the invention has the advantages of simple structure and low cost.
Drawings
FIG. 1 is a schematic view of a finger cutter of the present invention machining a helical internal gear;
FIG. 2 is a top view of the finger cutter drive mechanism of the present invention;
figure 3 is a front view of the finger cutter drive mechanism of the present invention.
Detailed Description
The invention is further described with reference to the following figures and examples. In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and the like are used in the indicated orientations and positional relationships based on the orientation shown in the drawings for convenience in describing the invention and simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be considered as limiting.
Example 1
The invention provides a method for generating and processing a spiral internal gear by a finger-shaped cutter without theoretical error, which comprises the following specific steps:
firstly, according to the tooth profile of the helical internal gear to be machined, the helical surface and the meshing surface formed by the tooth profile of the end surface of the helical internal gear are obtained, and the tooth profile of the tool without the theoretical error for machining the helical internal gear is obtained according to the tooth profile.
Then, according to the obtained tooth profile of the cutter without theoretical error, specification parameters, cutting depth and the like of the adopted finger-shaped cutter can be determined, then, as shown in figure 3, the axis of the finger-shaped cutter is perpendicular to the axis of the processed spiral internal gear, and the cutter rotates around the axis of the finger-shaped cutter to perform cutting movement on the tooth socket; the finger-shaped cutter moves along the direction parallel to the axis of the processed spiral internal gear while rotating to cut, namely, the whole tooth groove is cut; the theoretical tooth space helical angle of the spiral internal gear can be determined according to the previously calculated cutter tooth profile without theoretical error, so that when the finger cutter moves along the direction parallel to the axis of the processed spiral internal gear, the processed spiral internal gear also rotates around the axis of the finger cutter, and in a complete tooth space cutting movement stroke, the instantaneous rotation angle of the relative spiral movement of the processed spiral internal gear and the finger cutter is equal to the theoretical tooth space helical angle of the spiral internal gear, and the movement rate of the finger cutter and the rotation rate of the processed spiral internal gear accord with a corresponding relationship, so that the tooth space helical angle of the spiral internal gear can be formed.
After the finger-shaped cutter finishes one tooth socket cutting, the cutter stops moving along the direction parallel to the axial line of the processed spiral internal gear, the processed spiral internal gear rotates for a certain graduation around the axial line of the processed spiral internal gear so as to cut the next tooth socket, at the moment, the finger-shaped cutter can return to the initial position, and the processing process is repeated; the finger-shaped cutter can move along the opposite direction parallel to the axis of the processed spiral internal gear to cut the tooth grooves of the spiral internal gear next time, namely if the processing cutter moves from top to bottom at the last time, the processing cutter can cut from small to big from the last processing termination position, and meanwhile, the processed spiral internal gear rotates around the axis of the processed spiral internal gear to be changed correspondingly, so that idle stroke can be avoided, and processing efficiency is improved.
Therefore, as mentioned above, in the machining method provided by the present invention, the finger-shaped tool rotates around its own axis and performs a spiral motion with respect to the workpiece axis, so that the revolution surface of the finger-shaped tool and the spiral tooth surface of the spiral internal gear after machining are mutually enveloped, which belongs to a variation of the generating method, and the present invention has high machining accuracy compared with the forming method.
As shown in fig. 1 and 2, in the actual processing process, one finger-shaped cutter can be used, or a plurality of finger-shaped cutters can be arranged along the same circumference, when a plurality of cutters are used, a plurality of tooth sockets can be simultaneously cut by one stroke of the cutters, so that a plurality of tooth sockets can be simultaneously processed, the processing efficiency is remarkably improved, the abrasion of the finger-shaped cutter can be controlled, and the cutters do not need to be frequently replaced; meanwhile, the method can not only mill the spiral inner gear, but also conveniently realize grinding (the finger-shaped tool bit is replaced by a grinding tool such as a grinding wheel, an abrasive belt and the like) on the same equipment, can finish the whole process from rough machining, semi-finish machining to finish machining on the spiral inner gear, and meets the requirement of higher-level machining precision. In the processing method provided by the invention, the axis of the finger-shaped cutter is always vertical to the axis of the processed spiral internal gear, and the main motion and the feed motion in the whole milling process can be easily controlled, so that the machine tool adopting the processing method provided by the invention has a simple structure and lower corresponding manufacturing cost.
Example 2
The present embodiment is substantially the same as the embodiment of embodiment 1, and the difference from embodiment 1 is that, in this embodiment, when the finger-shaped cutter moves in the direction parallel to the axis of the processed helical internal gear, the finger-shaped cutter axis rotates around the axis of the processed helical internal gear, while the processed helical internal gear does not rotate around its axis and remains stationary, and the instantaneous rotation angle of the relative helical motion of the finger-shaped cutter and the processed helical internal gear also remains equal to the theoretical cogging helix angle of the helical internal gear, so that the helical internal gear cogging helix angle can be formed after the cutter completes one-time cogging cutting.
It should be understood that the above examples are only for clearly illustrating the technical solutions of the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.