阅读说明：本技术 一种粗精拉结构花键拉刀及其设计方法 (Coarse and fine drawing structure spline broach and design method thereof ) 是由 金伟峰 严鉴铂 赵艳文 任聪 朱殷达 于 2020-04-23 设计创作，主要内容包括：本发明公开了一种粗精拉结构花键拉刀及其设计方法。所公开的拉刀包括花键切削齿,花键切削齿沿切削方向包括多个同心布置的刀齿环,相邻两个刀齿环构成一组刀齿环,每一组刀齿环由一粗拉刀齿环和一精拉刀齿环构成,粗拉齿齿顶两侧设有内凹圆角；同组的精拉齿与粗拉齿齿升量之和为本组刀齿的齿升量,并且各组刀齿环的齿升量相同,同组刀齿环的精拉齿齿升量小于粗拉齿齿升量。所公开的方法为本发明拉刀的设计方法。本拉刀对刀刃崩尖有一定的抵抗能力,出现崩尖时,由于粗拉齿不参与最终齿廓的形成,不会影响齿轮齿面的加工质量；精拉齿切削量较少,受力小,耐用性好。(The invention discloses a rough and fine broaching structure spline broach and a design method thereof. The broach comprises spline cutting teeth, the spline cutting teeth comprise a plurality of concentrically arranged cutter tooth rings along a cutting direction, two adjacent cutter tooth rings form a group of cutter tooth rings, each group of cutter tooth rings consists of a rough broach tooth ring and a finish broach tooth ring, and two sides of the top of the rough broach tooth ring are provided with concave fillets; the sum of the tooth lifting amount of the fine broaching teeth and the tooth lifting amount of the rough broaching teeth of the same group is the tooth lifting amount of the group of cutter teeth, the tooth lifting amount of each cutter tooth ring of each group is the same, and the tooth lifting amount of the fine broaching teeth of the cutter tooth ring of the same group is smaller than the tooth lifting amount of the rough broaching teeth. The disclosed method is a design method of the broach of the present invention. The broach has certain resistance to the breaking of the cutting edge, and when the breaking occurs, the rough broach does not participate in the formation of the final tooth profile, so that the processing quality of the tooth surface of the gear is not influenced; the fine broaching teeth have less cutting amount, small stress and good durability.)

1. A rough finish broaching structure spline broach comprises a spline cutting tooth part, the spline cutting tooth part comprises a plurality of concentrically arranged cutter tooth rings, and is characterized in that,

along the cutting direction, two adjacent cutter tooth rings form a group of cutter tooth rings, and each group of cutter tooth rings consists of a rough broaching cutter tooth ring and a fine broaching cutter tooth ring;

the rough broaching tool toothed ring comprises a plurality of rough broaching teeth which are distributed annularly, and the fine broaching tool toothed ring comprises a plurality of fine broaching teeth which are distributed annularly; both sides of the top of each rough-drawing tooth are provided with concave fillets;

the sum of the tooth lifting amount of the fine broaching teeth and the tooth lifting amount of the rough broaching teeth of the same group is the tooth lifting amount of the group of cutter teeth, the tooth lifting amounts of the cutter tooth rings of the groups are the same, and the tooth lifting amounts of the rough broaching teeth of the cutter tooth rings of the groups are the same;

the tooth lifting amount of the fine broaching teeth of the same group of cutter tooth rings is smaller than that of the rough broaching teeth.

2. The rough and finish broaching structure spline broach according to claim 1, characterized in that in the same group of broach teeth, the rough broach teeth lift amount accounts for 70-90% of the single group teeth lift amount, and the finish broach teeth lift amount accounts for 10-30% of the single group teeth lift amount.

3. The rough and finish draw structural spline broach according to claim 1,h is the flute depth of the spline cutting tooth part, and the unit is as follows: mm; a is_f1The tooth lifting amount of the rough broaching tooth is unit mm; k is a rough-drawing tooth chip-containing system; l is the broaching length of the workpiece to be machined, unit: mm.

4. The rough and finish draw structural spline broach according to claim 1, wherein the fillet height is greater than the single set of tooth lifts.

5. The rough and finish broaching structure spline broach according to claim 1, wherein two circumferentially adjacent concave fillets in the same rough broach ring are located in the same arc, and the radius Rs of the arc is:

a is the height of an inner concave fillet of the rough drawing tooth, and the value range of a is 0.35-0.65 mm;

c is the tooth top arc tooth thickness of the workpiece to be machined when the outer diameter of the broach is R, unit: mm;

b is the thickness of the top of the rough cut tooth, b is (0.5-0.6) c, unit: mm;

S_R-athe tooth arc tooth thickness when the broach is in the outer diameter R-a is as follows: mm.

6. The rough and finish drawn structure spline broach according to claim 1, further comprising a rear shank portion, a spline aligning tooth portion, a circular hole cutting portion, a front shank portion, which are sequentially arranged in a cutting direction.

7. The method for designing a rough and finish drawn structure spline broach according to claim 1, characterized in that the method comprises:

(1) determining a single group of tooth lifting amount a according to the modulus and the material tensile strength of a workpiece to be machined_f0；

(2) Determining the tooth lifting amount of the rough broaching tooth and the tooth lifting amount of the fine broaching tooth in the single group of the tooth: a is_f1+a_f2The tooth lifting amount of the fine broaching teeth of the same group is less than that of the rough broaching teeth of af 0;

(3) and determining the height a of the concave fillet on the rough broach.

8. The method for designing a rough and fine broaching structure spline broach according to claim 7, wherein the tooth lift of the rough broaching tooth accounts for 70% -90% of the tooth lift of a single group, and the tooth lift of the fine broaching tooth accounts for 10% -30% of the tooth lift of the single group.

9. The method of designing a rough and finish drawn structural spline broach according to claim 7, characterized in that the method further comprises:

(4) determining a coarse broaching tooth chip-containing coefficient K according to the tensile strength of the material of the workpiece and the tooth lifting amount of the coarse broaching tooth determined in the step (2);

(5) determining the depth H of a broach chip pocket:and L is the broaching length of the workpiece to be machined.

10. The method of designing a rough and finish drawn structural spline broach according to claim 8, characterized in that the method further comprises:

(6) determining the radius Rs of circular arcs of two concave fillets which are adjacent in the same rough broach toothed ring in the circumferential direction:

the value range of a is 0.35-0.65mm, unit: mm;

b is the thickness of the top of the rough cutting tooth, b is (0.5-0.6) × c, and c is the thickness of the top arc tooth when the outer diameter of the broach of the workpiece to be machined is R;

S_R-athe thickness of the tooth top of the tooth arc when the broach is in the outer diameter R-a is as follows: mm.

Technical Field

The invention relates to a cutter for machining, in particular to a spline broach with a fine and rough drawing structure.

Background

At present, a single-tooth gradually-formed machining structure is generally adopted by an involute spline or a rectangular spline broach at home and abroad, all cutter teeth are concentric circles, in the cutting process, the rear cutter tooth is higher than the front cutter tooth, a layer of metal is pulled off from each cutter tooth, and the machining of the spline tooth profile is completed layer by layer.

Disclosure of Invention

Aiming at the problems and defects in the prior art, the invention provides a rough and fine drawing structure spline broach.

For this purpose, the fine and rough broaching structure spline broach provided by the invention comprises a spline cutting tooth part, the spline cutting tooth part comprises a plurality of concentrically arranged cutter tooth rings,

along the cutting direction, two adjacent cutter tooth rings form a group of cutter tooth rings, and each group of cutter tooth rings consists of a rough broaching cutter tooth ring and a fine broaching cutter tooth ring;

the rough broaching tool toothed ring comprises a plurality of rough broaching teeth which are distributed annularly, and the fine broaching tool toothed ring comprises a plurality of fine broaching teeth which are distributed annularly; both sides of the top of each rough-drawing tooth are provided with concave round corners,

the sum of the tooth lifting amount of the fine broaching teeth and the tooth lifting amount of the rough broaching teeth of the same group is the tooth lifting amount of the group of cutter teeth, the tooth lifting amounts of the cutter tooth rings of the groups are the same, and the tooth lifting amounts of the rough broaching teeth of the cutter tooth rings of the groups are the same; namely, the fine broaching tooth lifting amount of each group of cutter tooth rings is the same;

the tooth lifting amount of the fine broaching teeth of the same group of cutter tooth rings is smaller than that of the rough broaching teeth;

concretely, thick finish broaching structure spline broach still includes back stalk portion, spline calibration tooth portion, round hole cutting portion, preceding stalk portion, back stalk portion, spline calibration tooth portion, spline cutting tooth portion, round hole cutting portion, preceding stalk portion set gradually along the cutting direction.

Meanwhile, the invention provides a design method of a rough and fine broaching structure spline broach. The design method provided by the invention comprises the following steps:

(1) determining a single group of tooth lifting amount a according to the modulus and the material tensile strength of a workpiece to be machined_f0；

(2) Determining the tooth lifting amount of the rough broaching tooth and the tooth lifting amount of the fine broaching tooth in the single group of the tooth: a is_f1+a_f2The tooth lifting amount of the fine broaching teeth of the same group is less than that of the rough broaching teeth of af 0;

(3) and determining the height a of the concave fillet on the rough broach.

Further, the method further comprises:

(4) determining a coarse broaching tooth chip-containing coefficient K according to the tensile strength of the material of the workpiece and the tooth lifting amount of the coarse broaching tooth determined in the step (2);

(5) the broach flute depth H is determined.

(6) And determining the radius Rs of circular arcs of two concave fillets which are adjacent in the same rough broach toothed ring in the circumferential direction.

Optionally, in the same group of cutter teeth, the tooth lifting amount of the rough broaching teeth accounts for 70-90% of that of the single group of teeth, and the tooth lifting amount of the fine broaching teeth accounts for 10-30% of that of the single group of teeth.

Alternatively to this, the first and second parts may,h is the flute depth of the spline cutting tooth part, and the unit is as follows: mm; a is_f1The tooth lifting amount of the rough broaching tooth is as follows: mm; k is a rough-drawing tooth chip-containing system; l is the broaching length of the workpiece to be machined, unit: mm.

Preferably, the height of the concave fillet is larger than the lifting amount of the single group of teeth.

Preferably, two adjacent concave fillets in the same rough broach ring in the circumferential direction are located on the same circular arc, and the radius Rs of the circular arc is as follows:

a is the height of an inner concave fillet of the rough drawing tooth, and the value range of a is 0.35-0.65 mm;

c is the tooth top arc tooth thickness of the workpiece to be machined when the outer diameter of the broach is R, unit: mm;

b is the thickness of the top of the rough cut tooth, b is (0.5-0.6) c, unit: mm;

S_R-athe tooth arc tooth thickness when the broach is in the outer diameter R-a is as follows: mm.

Optionally, the spline cutting teeth comprise 20-30 sets of cutter ring teeth.

Compared with the prior art, the broach takes 2 cutter teeth as a group, the former cutter tooth cuts most of metal and does not participate in the processing of the final tooth profile, although the stress is larger, the structural strength is good, the tip breaking is not easy to occur, and even if the tip breaking occurs, the processing quality of the involute tooth surface cannot be influenced because the tip breaking does not participate in the formation of the final tooth profile; the cutting allowance of the latter cutter tooth is smaller, and the processing of the involute tooth profile is completed; the stress is small, the tip is not easy to collapse, and the tensile injury resistance is strong; meanwhile, the rough drawing teeth have low requirements on the cutting edge, and the fine drawing teeth have small abrasion, so that the single processing quantity of the broaching tool can be increased to a certain degree; and because the abrasion of the finish drawing teeth is small, under the condition of certain sharpening amount, the sharpening times of the broaching tool are obviously increased.

Drawings

FIG. 1 is a schematic view of a spline cutter of the present invention;

FIG. 2 is a schematic view of the rough broaching and the fine broaching of the present invention;

FIG. 3 is a schematic view of a rough broach according to the present invention;

fig. 4 is a reference schematic diagram of the spline broach structure of the present invention.

Detailed Description

The following definitions apply to terms used in this specification unless otherwise limited by special circumstances. Moreover, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present valve belongs. In case of conflict, the present specification, including definitions, will control.

For the purposes of the present invention, some terms used in this specification have the following meanings:

as used herein, the directional terms "inner", "axial" and "radial" are used in a direction on the page of the drawings or corresponding direction in space as shown in the drawings.

The invention aims at the problems that the traditional single-tooth gradual-forming broach is easy to tip and has short service life, and designs an involute spline broach with a coarse and fine drawing structure, wherein 2 cutter teeth are taken as a group, the former cutter tooth cuts most of metal but does not participate in the processing of the final spline tooth profile, namely the coarse broach is used for cutting most of metal, although the stress is larger, the structural strength is good, the cutter blade tip has certain resistance capacity, and even though the tip is broken, the coarse broach does not participate in the formation of the final tooth profile, so that the processing quality of the tooth surface of a gear cannot be influenced; the last cutter tooth finishes finish machining of the spline tooth profile, namely the finish broaching tooth, and the finish broaching tooth has the advantages of less cutting amount, small stress and good durability; the integral profile of the spline cutting teeth is conical, and a plurality of groups of cutter tooth rings are distributed on the broach body according to the size requirements of parts to be processed (such as inner holes, involute splines, rectangular splines and the like).

The structural parameters of the rough and finish drawing structure spline broach comprise the tooth lifting amount of each group of cutter teeth, the groove shape of the cutter and the shape parameters of the rough cutting tooth cutter, and the design methods of other parameters (such as tooth pitch, front angle, edge band structure, cutter handle structure and the like) are the same as the traditional design method. The relative interpretation of the terms to which the present invention relates is understood in conjunction with the descriptions in table 1, fig. 2 and fig. 3.

TABLE 1

The single-group tooth lifting amount a is determined according to the modulus and the material tensile strength of the workpiece to be machined_f0One specific example is shown in table 2.

TABLE 2a_f0Recommendation table (Unit: mm)

The chip containing coefficient K of the rough broaching tooth is determined according to the tensile strength of a material of a workpiece to be processed and the tooth lifting amount of the rough broaching tooth; an example is shown in table 3, where the flute coefficients of the rough broach are selected from table 3, and the content of "/" is not suggested to adopt the structural design of the present invention.

TABLE 3 recommendation table for chip-containing coefficient K of rough-drawn teeth

The concave fillets are arranged on the two sides of the top of the rough broaching tooth to better ensure the strength of the rough broaching tooth and avoid influencing the processing quality when the rough broaching tooth is subjected to tip breakage, and the height value a of the concave fillets on the top of the rough broaching tooth is preferably larger than the tooth lifting amount a_f0. An empirical example is a taking 0.35-0.65 mm. The relief angle of the concave fillet (p-p in figure 3) is determined according to the machining requirements, for example, 8-15 deg..

The radius Rs of the circular arcs of two concave fillets which are adjacent in the same rough broach toothed ring in the circumferential direction is calculated by the formula (1), and the error in a reasonable range is allowed, such as +/-0.5 mm.

The tooth top arc tooth thickness c of the workpiece to be machined when the outer diameter of the broach is R and the value of the outer diameter of the broach are R are determined according to the design method of the existing cutter.

Based on the structure and the design method of the invention, an integral spline broach structure is shown in fig. 4 and comprises a rear handle part, spline calibration teeth, spline cutting teeth, a round hole cutting part and a front handle part; the rear handle part, the spline calibration teeth, the spline cutting teeth, the round hole cutting part and the front handle part are sequentially arranged along the cutting direction.