阅读说明：本技术 一种不等齿距滚刀、锥度齿厚平齿根结构齿轮的加工方法 (Method for processing gear with unequal-pitch hobbing cutter and taper tooth thickness flat tooth root structure ) 是由 王艳丽 林欧 唐永鹏 于 2020-06-11 设计创作，主要内容包括：为了在滚齿阶段,一次性装夹滚切出锥度齿厚平齿根结构的齿轮,避免多工序、重复装夹造成精度变差、效率低下、齿侧相接处刀痕的技术问题,本发明提出了一种不等齿距滚刀、锥度齿厚平齿根结构齿轮的加工方法。不等齿距滚刀包括刀体和齿排；齿排至少有八个,沿刀体端面圆周均布；单个齿排包括沿刀体轴线排布的至少三个切削齿；位于不同齿排的切削齿依次沿刀体作螺旋线排列；单个齿排中切削齿的结构和排布规律为：以刀体一侧的一个完整齿作为基准齿,以基准齿的齿厚和齿距为基准尺寸,在该基准尺寸上以齿厚增量Δss和齿距增量Δp使齿厚、齿距逐齿增大,形成变齿厚、变齿距的齿排。本发明可一次性滚削加工出锥度齿厚平齿根的齿轮成品。(The invention provides a method for processing a gear with unequal tooth pitch, a tapered tooth thickness and a flat tooth root structure, which aims to clamp and hobbing the gear with the tapered tooth thickness and the flat tooth root structure at one time in a gear hobbing stage and avoid the technical problems of poor precision, low efficiency and tool marks at a tooth side joint caused by multiple processes and repeated clamping. The unequal-pitch hob comprises a hob body and a row of teeth; at least eight tooth rows are uniformly distributed along the circumference of the end surface of the cutter body; the single tooth row comprises at least three cutting teeth arranged along the axis of the cutter body; the cutting teeth positioned in different tooth rows are arranged in a spiral line along the cutter body in sequence; the structure and arrangement rule of the cutting teeth in the single tooth row are as follows: one complete tooth on one side of the cutter body is used as a reference tooth, the tooth thickness and the tooth pitch of the reference tooth are used as reference dimensions, and the tooth thickness and the tooth pitch are increased tooth by tooth according to the tooth thickness increment delta ss and the tooth pitch increment delta p on the reference dimensions, so that tooth rows with variable tooth thickness and variable tooth pitch are formed. The invention can process the gear finished product with taper tooth thickness and flat tooth root by one-time hobbing.)

1. A hobbing cutter with unequal tooth pitches comprises a cutter body with an axial inner hole in the middle and a tooth row arranged on the outer surface of the cutter body; the method is characterized in that:

at least eight tooth rows are uniformly distributed along the circumference of the end face of the cutter body;

the single tooth row comprises at least three cutting teeth which are arranged along the axis direction of the cutter body; the cutting teeth positioned in different tooth rows are arranged in a spiral line along the cutter body in sequence;

the structure and arrangement rule of the cutting teeth in the single tooth row are as follows: taking one complete tooth on one side of the cutter body as a reference tooth, taking the tooth thickness and the tooth pitch of the reference tooth as reference dimensions, and increasing the tooth thickness and the tooth pitch one by one on the basis of the tooth thickness increment delta ss and the tooth pitch increment delta p on the reference dimensions to form tooth rows with variable tooth thickness and variable tooth pitch;

the increment of tooth thickness Δ ss and the increment of pitch Δ p are determined by the following equations:

Δss＝Δp＝ΔS*Pn/(k*B)；

in the formula: b is the tooth width of the gear to be processed; pn is the tooth pitch of the gear to be processed; delta S is the difference between the tooth thickness of the large end of the gear to be processed and the tooth thickness of the small end of the gear; and k is the speed ratio of the cutter fleeing speed of the hobbing machine to the axial feeding speed.

2. The unequal pitch hob of claim 1, wherein:

the complete tooth is the first complete tooth close to the end face of the cutter body.

3. The unequal pitch hob of claim 1, wherein:

the complete tooth is the Nth complete tooth close to the end face of the cutter body; n is more than or equal to 2.

4. The unequal pitch hob of any one of claims 1 to 3, wherein:

the pressure angle of two adjacent cutting teeth in the same tooth row is modified according to the following principle:

and taking the pressure angle of the corresponding gear tooth to be machined as a reference, correspondingly increasing the pressure angle corresponding to the cutting tooth with a large modulus, and correspondingly reducing the pressure angle corresponding to the cutting tooth with a small modulus.

5. The method for processing the gear with the tapered tooth thickness and the flat root structure by using the unequal-pitch hobbing cutter as claimed in any one of claims 1 to 4, is characterized by comprising the following steps of:

step 1, installing a cutter bar for a hob;

step 2, mounting the hob cutter on a gear hobbing machine, and ensuring that the runout of the shaft bases at two ends of the hob cutter is not more than 0.015mm and the runout directions are consistent;

step 3, mounting a hobbing clamp and adjusting the alignment center and the end face to ensure that the radial runout of the lower conical surface of the clamp is not more than 0.01mm and the end face runout is not more than 0.01 mm;

step 4, installing a workpiece to be processed;

setting hob cutting parameters including the axial feeding speed, the hob fleeing initial position and the hob fleeing termination position of the hob, wherein the hob fleeing initial position is the position of the reference tooth of the hob, and the hob fleeing termination position is the position of the hob fleeing initial position plus k times of the tooth width of the gear to be processed;

step 6, rolling and cutting the workpiece;

when a workpiece is rolled and cut, the hob simultaneously feeds along the axial direction and the tangential direction, and the resultant of the two feed motions enables the hob to move along a straight line which is crossed with the axis of the workpiece to form a certain angle, so that a gear with a straight tooth root is rolled and cut; meanwhile, the workpiece conical surface is continuously cut by the gradual change of the tooth thickness of the hob, and the workpiece is cut into the workpiece from the small tooth thickness end of the hob to form the large involute tooth thickness end until the small tooth thickness end of the workpiece is cut by the large tooth thickness end of the hob.

Technical Field

The invention relates to the technical field of manufacturing of gears or racks, in particular to a hob with unequal tooth pitches and a method for machining a gear with a taper tooth thickness and a flat tooth root structure by using the hob.

Background

As shown in fig. 1 and 2, a gear having a taper-tooth-thickness taper-root structure is generally used, in which the tooth thickness gradually decreases from one end surface to the other end surface in the tooth direction, and the root circle also gradually decreases from one end surface to the other end surface to form a taper-tooth-thickness structure. The gear with the structure has the advantages that the hob design is simple, the hob tooth thickness is designed according to the large end of the product tooth thickness, the hob tooth crest height is designed according to the small end of the product tooth thickness, and the hob feed track is inclined by a root cone angle during hob machining so as to meet the product requirements.

Fig. 3 and 4 show a gear having a tapered tooth thickness flat root structure, which has been widely used in automobile clutches, and the tooth thickness of the gear is tapered in the tooth direction, but the root circle is constant in the tooth direction and remains constant. The gear with the structure is generally machined by a general machining method through two procedures of rolling straight teeth and forming and grinding the tooth side, namely, the gear is firstly subjected to gear hobbing and then is ground for a plurality of times. The processing method is not easy to control the size and the symmetry, and has long processing time and more processing procedures, thereby resulting in low efficiency, poor precision and high processing cost.

Disclosure of Invention

The invention provides a method for processing a gear with unequal tooth pitch, a tapered tooth thickness and a flat tooth root structure, which aims to clamp and hobbing the gear with the tapered tooth thickness and the flat tooth root structure at one time in a gear hobbing stage and avoid the technical problems of poor precision, low efficiency and tool marks at a tooth side joint caused by multiple processes and repeated clamping.

The technical scheme of the invention is as follows:

a hobbing cutter with unequal tooth pitches comprises a cutter body with an axial inner hole in the middle and a tooth row arranged on the outer surface of the cutter body; it is characterized in that:

at least eight tooth rows are uniformly distributed along the circumference of the end face of the cutter body;

the single tooth row comprises at least three cutting teeth which are arranged along the axis direction of the cutter body; the cutting teeth positioned in different tooth rows are arranged in a spiral line along the cutter body in sequence;

the structure and arrangement rule of the cutting teeth in the single tooth row are as follows: taking one complete tooth on one side of the cutter body as a reference tooth, taking the tooth thickness and the tooth pitch of the reference tooth as reference dimensions, and increasing the tooth thickness and the tooth pitch one by one on the basis of the tooth thickness increment delta ss and the tooth pitch increment delta p on the reference dimensions to form tooth rows with variable tooth thickness and variable tooth pitch;

the increment of tooth thickness Δ ss and the increment of pitch Δ p are determined by the following equations:

Δss＝Δp＝ΔS*Pn/(k*B)；

in the formula: b is the tooth width of the gear to be processed; pn is the tooth pitch of the gear to be processed; delta S is the difference between the tooth thickness of the large end of the gear to be processed and the tooth thickness of the small end of the gear; and k is the speed ratio of the cutter fleeing speed of the hobbing machine to the axial feeding speed.

Further, the complete tooth is the first complete tooth close to the end face of the cutter body.

Or the complete tooth is the Nth complete tooth close to the end face of the cutter body; n is more than or equal to 2.

Further, the pressure angle of two adjacent cutting teeth in the same tooth row is modified according to the following principle:

and taking the pressure angle of the corresponding gear tooth to be machined as a reference, correspondingly increasing the pressure angle corresponding to the cutting tooth with a large modulus, and correspondingly reducing the pressure angle corresponding to the cutting tooth with a small modulus.

The invention also provides a method for processing the gear with the taper tooth thickness flat root structure by using the hob with unequal tooth pitches, which is characterized by comprising the following steps of:

step 1, installing a cutter bar for a hob;

step 2, mounting the hob cutter on a gear hobbing machine, and ensuring that the runout of the shaft bases at two ends of the hob cutter is not more than 0.015mm and the runout directions are consistent;

step 3, mounting a hobbing clamp and adjusting the alignment center and the end face to ensure that the radial runout of the lower conical surface of the clamp is not more than 0.01mm and the end face runout is not more than 0.01 mm;

step 4, installing a workpiece to be processed;

setting hob cutting parameters including the axial feeding speed, the hob fleeing initial position and the hob fleeing termination position of the hob, wherein the hob fleeing initial position is the position of the reference tooth of the hob, and the hob fleeing termination position is the position of the hob fleeing initial position plus k times of the tooth width of the gear to be processed;

step 6, rolling and cutting the workpiece;

when a workpiece is rolled and cut, the hob simultaneously feeds along the axial direction and the tangential direction, and the resultant of the two feed motions enables the hob to move along a straight line which is crossed with the axis of the workpiece to form a certain angle, so that a gear with a straight tooth root is rolled and cut; meanwhile, the workpiece conical surface is continuously cut by the gradual change of the tooth thickness of the hob, and the workpiece is cut into the workpiece from the small tooth thickness end of the hob to form the large involute tooth thickness end until the small tooth thickness end of the workpiece is cut by the large tooth thickness end of the hob.

The invention has the advantages that:

1. the invention can process the gear finished products with the taper tooth thickness and the flat tooth root shown in the figures 3 and 4 by one-time hobbing, solves the problems of large tool setting difficulty, obvious workpiece tool receiving mark and low processing precision caused by multiple procedures and repeated clamping during processing of the products, simultaneously omits the tooth side forming grinding processing of 2X Z (Z is the number of teeth of the gear to be processed), and greatly improves the production efficiency.

2. The invention reduces the investment of a gear grinding process machine tool, a cutter, a clamp, manpower, electric power, cutting fluid and the like, and reduces the processing cost by 40 percent.

3. If the tooth thickness is increased and the tooth pitch is unchanged, the hob needs to be ground at a fixed point, and the tooth thickness is increased and the tooth pitch is increased, so that the tooth space size is unchanged, the hob is beneficial to finishing the processing at one time, and the processing difficulty and the processing efficiency are greatly reduced.

Drawings

FIG. 1 is a schematic illustration of a gear wheel with a tapered tooth thickness and a tapered tooth root configuration.

Fig. 2 is a view in the direction P (single tooth) of fig. 1.

Fig. 3 is a schematic view of a gear with a tapered tooth thickness and a flat tooth root structure.

Fig. 4 is a view in the direction P (single tooth) of fig. 3.

FIG. 5 is an axial view of the unequal pitch hob of the present invention.

FIG. 6 is a schematic end view of the unequal pitch hob of the present invention.

FIG. 7 is a perspective view of the unequal pitch hob of the present invention.

FIG. 8 is a second perspective view of the unequal pitch hob of the present invention.

Description of reference numerals:

1, a cutter body; 11-axial inner bore; 2-tooth row; 21-cutting teeth.

Detailed Description

As shown in fig. 5, 6, 7 and 8, the unequal pitch hob provided by the invention comprises a hob body 1 with an axial inner hole 11 in the middle and at least eight rows of teeth 2 arranged on the outer surface of the hob body 1; the eight tooth rows 2 are uniformly distributed along the circumference of the end face of the cutter body; the single tooth row 2 comprises at least three cutting teeth 21 which are arranged along the axial extension of the cutter body, and a tooth groove is formed between every two adjacent cutting teeth 21 in the single tooth row 2; the cutting teeth 21 include tooth tops, left and right tooth flanks, and tooth root faces, and the included angle between the tooth flanks and the cutter body section is a pressure angle. The cutting teeth in different tooth rows are arranged in a spiral line along the cutter body in sequence, the helix angle of the formed hob is beta, and the helix angle beta is determined by the parameters of the gear to be processed.

The cutting teeth 21 of a single row 2 have the following structural characteristics and arrangement rules: the method is characterized in that one complete tooth on one side of the cutter body 1 is taken as a reference tooth, the tooth thickness and the tooth pitch of the reference tooth are taken as reference dimensions, and the tooth thickness and the tooth pitch are increased tooth by tooth according to the reference dimensions by the tooth thickness increment delta ss and the tooth pitch increment delta p to form a tooth row with variable tooth thickness and variable tooth pitch.

The complete tooth can be the first complete tooth close to the end face of the cutter body, and the hob is most economical, but the complete tooth can not be adjusted conveniently on site; the complete teeth can be the second complete teeth, the third complete teeth or the middle complete teeth close to the end face of the hob, and at the moment, a certain allowance is reserved, so that field adjustment is facilitated, but the overall length of the hob is long, and the economical efficiency is reduced.

Referring to fig. 5, the method for calculating the tooth thickness increment Δ ss and the pitch increment Δ p includes: setting the tooth width of a gear to be machined as B, the tooth pitch of the gear to be machined as Pn, the difference value between the tooth thickness S2 of the large end of the gear to be machined and the tooth thickness S1 of the small end of the gear to be machined as delta S, and the speed ratio of the tool fleeing speed of the hobbing machine to the axial feeding speed as k, then

The increment of the tooth thickness of the cutting tooth is S2-S1 is Δ S Pn/(k B); wherein: (Δ S) S2-S1; s1 is the small end tooth thickness of a single tooth in the gear to be processed; s2 represents the tooth thickness of the big end of a single tooth in the gear to be processed; s1 is the tooth thickness of the preceding cutting tooth and s2 is the tooth thickness of the following cutting tooth.

The increment of the pitch of the cutting teeth is p2-p1 is Δ ss.

The process of processing the gear shown in the figures 3 and 4 by using the invention comprises the following steps:

1. the hob is provided with a hob rod. Before installing the cutter arbor, clean with the non-woven fabrics with the cutter arbor, ensure to have not debris on the contact surface, check hobbing cutter shaft platform with the amesdial on dress knife rest and beat, must not be greater than 0.01 mm.

2. And a hob is arranged on the gear hobbing machine. After the hob is installed, the shaft bosses at the two ends of the hob are checked to jump by using a dial indicator, the shaft bosses at the two ends should jump not more than 0.015mm, and the jumping directions are consistent.

3. And (5) installing a hobbing clamp. And (3) installing a hobbing clamp and adjusting the alignment center and the end face, checking the radial runout and the end face runout of the lower conical surface of the clamp by using a dial indicator until the radial runout of the lower conical surface of the clamp is not more than 0.01mm and the end face runout is not more than 0.01mm, and finishing the adjustment and alignment.

4. And (5) mounting the workpiece. The installation waits to process the work piece, blows clean locating hole and locating surface with the air gun before the installation, checks whether have burr, turn-ups, if have burr, turn-ups, should polish burring, turn-ups.

5. Setting hob cutting parameters, including the axial feeding speed of the hob, the fleeing cutter speed, the fleeing cutter initial position and the fleeing cutter end position, wherein the fleeing cutter initial position is the position of the reference tooth of the hob, the fleeing cutter end position is the fleeing cutter initial position plus k times of the tooth width of the gear to be processed, and the ratio of the fleeing cutter speed to the axial feeding speed of the hob is ensured to be consistent with the k value when the hob is designed.

6. And rolling and cutting the workpiece. When a workpiece is rolled and cut, the hob simultaneously feeds along the axial direction and the tangential direction, and the resultant of the two feeds enables the hob to move along a straight line which intersects with the axis of the workpiece at a certain angle, so as to roll and cut the gear with a straight tooth root. Meanwhile, the workpiece conical surface is continuously cut by the gradual change of the tooth thickness of the hob, and the workpiece is cut into the workpiece from the small tooth thickness end of the hob to form the large involute tooth thickness end until the small tooth thickness end of the workpiece is cut by the large tooth thickness end of the hob.

When the hob cutter is used for cutting a workpiece, in order to ensure that the cutting teeth are correctly meshed with the gear to be processed, the base section of the hob cutter is equal to the base section of the workpiece. Two adjacent cutting teeth in the same tooth row on the hob cut two tooth flanks of one tooth of the gear, so that the base pitch of two adjacent cutting teeth in the same tooth row on the hob is equal to the base pitch of the gear to be machined, see formula 1. Because the tooth pitch and the tooth thickness of the hob with unequal tooth pitches are gradually changed, the tooth pitches of two adjacent teeth in the same tooth row on the hob are unequal, the tooth pitch is equal to the product of pi and the modulus, and the modulus of two adjacent cutting teeth in the same tooth row on the hob is also equal to unequal, see formulas 2-5. The base sections are equal and the modulus is different, so that the pressure angle corresponding to the cutting tooth with the larger modulus is correspondingly increased, and the pressure angle corresponding to the cutting tooth with the smaller modulus is correspondingly decreased, see formula 6.

According to the rule, the pressure angle of the hob is modified.

m1 ═ m2 ═ m ═ co (α 2) ═ m ═ co (α) formula 1

P1 pi m1 formula 2

P2 pi m2 formula 3

P1 ≠ P2 type 4

m1 ≠ m2 type 5

Alpha 1< alpha 2 formula 6

In the above formula:

m1 is the modulus of the previous cutting tooth;

m2 is the modulus of the latter cutting tooth;

m is the module of the gear;

α 1 is the pressure angle of the previous cutting tooth;

α 2 is the pressure angle of the latter cutting tooth;

alpha is the pressure angle of the gear;

p1 is the pitch of the previous cutting tooth;

p2 is the pitch of the latter cutting tooth.