阅读说明：本技术 一种等切削前角插齿刀及其构造方法 (Slotting cutter with equal cutting rake angles and construction method thereof ) 是由 李佳 徐海波 金永泉 于 2020-07-11 设计创作，主要内容包括：本发明公开了一种等切削前角插齿刀,包括刀体和沿刀体均布的刀齿,每个刀齿由左切削刃、右切削刃、顶刃、前刀面、左后刀面、右后刀面及顶后刀面构成；左、右切削刃在轴截面上的投影为渐开线,且分别位于被加工左、右渐开线齿面的共轭面上；左、右切削刃上各点的切削前角相等,且左切削刃的切削前角与右切削刃的切削前角相等；前刀面是使左、右切削刃的切削前角恒定的自由曲面；左、右后刀面分别为若干条左、右切削刃构成的自由曲面；顶后刀面为圆锥面；顶刃为前刀面与顶后刀面的交线。本发明还公开了一种如上述等切削前角插齿刀的构造方法。本发明的插齿刀左、右切削刃的切削前角一致,既保证较高加工精度,又保证较好表面质量,且保证精度恒定。(The invention discloses a slotting cutter with equal cutting rake angles, which comprises a cutter body and cutter teeth uniformly distributed along the cutter body, wherein each cutter tooth consists of a left cutting edge, a right cutting edge, a top edge, a front cutter face, a left rear cutter face, a right rear cutter face and a top rear cutter face; the projections of the left cutting edge and the right cutting edge on the axial section are involute curves and are respectively positioned on conjugate surfaces of tooth surfaces of the left involute curve and the right involute curve to be processed; the cutting rake angles of all points on the left cutting edge and the right cutting edge are equal, and the cutting rake angle of the left cutting edge is equal to the cutting rake angle of the right cutting edge; the rake face is a free curved surface which makes the cutting rake angles of the left and right cutting edges constant; the left and right rear cutter faces are free curved surfaces formed by a plurality of left and right cutting edges respectively; the top rear cutter face is a conical face; the top blade is the intersection line of the front blade face and the top rear blade face. The invention also discloses a construction method of the equal cutting rake angle slotting cutter. The cutting rake angles of the left cutting edge and the right cutting edge of the slotting cutter are consistent, so that high machining precision is guaranteed, good surface quality is guaranteed, and the precision is constant.)

1. A slotting cutter with equal cutting rake angles comprises a cutter body and cutter teeth uniformly distributed along the circumference of the cutter body, wherein each cutter tooth consists of a left cutting edge, a right cutting edge, a top edge, a front cutter face, a left rear cutter face, a right rear cutter face and a top rear cutter face; the cutting tool is characterized in that the projections of the left cutting edge and the right cutting edge on the axial section are involutes and are respectively positioned on conjugate surfaces of tooth surfaces of the processed left involute and the processed right involute; the cutting rake angles of all points on the left cutting edge are equal, the cutting rake angles of all points on the right cutting edge are equal, and the cutting rake angle of the left cutting edge is equal to the cutting rake angle of the right cutting edge; the left rear cutter face is a free curved surface formed by a plurality of left cutting edges; the right rear cutter face is a free curved surface formed by a plurality of right cutting edges; the top rear cutter face is a conical face; the top blade is the intersection line of the front blade face and the top rear blade face.

2. The equal cutting rake slotting cutter of claim 1 wherein the cutter teeth are straight or skewed teeth.

3. The equal cutting rake angle slotting cutter according to claim 1, wherein the rake surface is a free-form surface in which the cutting rake angle of the left cutting edge and the cutting rake angle of the right cutting edge are constant.

4. The equal cutting rake angle slotting cutter according to claim 1, wherein the cutting rake angle of the left and right cutting edges is 5 to 15 °.

5. The equal cutting rake slotting cutter according to claim 1 wherein the left and right re-sharpened cutting edges remain on the conjugate plane of the involute flank being machined.

6. A method of constructing a constant cutting rake gear cutter as claimed in any one of claims 1 to 5, the method comprising: setting the tooth surface of the processed part in contact with the left cutting edge as an A tooth surface, setting the tooth surface of the processed part in contact with the right cutting edge as a B tooth surface, establishing a conjugate tooth surface model of the A tooth surface of the processed part according to a conjugate principle, selecting part points on the conjugate tooth surface of the A tooth surface of the processed part according to a constraint condition as cutting edge model points, and fitting the model points by using a sample curve to obtain a space curve, wherein the curve is the left cutting edge; and establishing a conjugate tooth surface model of the tooth surface of the part B to be processed, selecting partial points on the conjugate tooth surface of the part B to be processed according to constraint conditions as cutting edge model value points, and fitting the model value points by using a sample curve to obtain a space curve, wherein the curve is a right cutting edge.

7. The method for constructing a constant cutting rake angle slotting cutter according to claim 6, wherein the displacement coefficient of the conjugate tooth surface of the part A to be machined is changed to obtain a series of conjugate tooth surfaces of the tooth surface of the part A to be machined, a series of left cutting edges are further obtained, the left cutting edges are subjected to surface fitting, and the formed curved surface is the left flank surface; and changing the deflection coefficient of the conjugate tooth surface of the part B to be processed to obtain a series of conjugate tooth surfaces of the tooth surface of the part B to be processed, further obtaining a series of right cutting edges, and performing curve fitting on the right cutting edges to form a curve which is the right back cutter surface.

8. The method of claim 6, wherein said shaping point M is located on the left cutting edge_i1,2, 3 … n, establishing a tool cutting angle reference plane comprising a base plane, a cutting plane and an orthogonal plane; let line segment M_iH_iIs located on the intersection line of the orthogonal plane and the base plane, andthe direction of (1) is directed to the right cutting edge side; in orthogonal plane, the over-type value M_iLine segment M_iN_iTo makePointing to the inside of the cutter teeth to make an angle N_iM_iH_iA cutting rake angle equal to the set left cutting edge; corresponding to the model value point U on the right cutting edge_i1,2, 3 … n, establishing a tool cutting angle reference plane comprising a base plane, a cutting plane and an orthogonal plane; line segment U_iV_iIs located on the intersection line of the orthogonal plane and the base plane, andthe direction of (a) is directed to the left cutting edge side; in the orthogonal plane, the over-type value point U_iLine segment making U_iW_iTo make

Technical Field

The invention relates to the field of cutters for gear machining, in particular to a slotting cutter with equal cutting rake angles and a construction method thereof.

Background

At present, gear shaping is an economical and efficient involute gear machining method. However, due to the adoption of design methods such as involute generating and shaping slotting tools, the slotting tool has theoretical design errors, the change range of the cutting rake angle is large, the machining precision is low, the machining quality is poor, and particularly, the precision consistency of the left tooth surface and the right tooth surface is difficult to ensure in the bevel gear machining. Meanwhile, in the gear shaping process, when the gear shaping cutter cuts into and cuts out a workpiece, the fluctuation of cutting force is large, and the processing quality and the service life of the cutter are further influenced.

Disclosure of Invention

The invention provides a slotting cutter with equal cutting rake angles and a construction method thereof, aiming at ensuring the economical and efficient characteristics of slotting and obtaining better machining precision and surface quality.

The technical scheme adopted by the invention for solving the technical problems in the prior art is as follows: a slotting cutter with equal cutting rake angles comprises a cutter body and cutter teeth uniformly distributed along the circumference of the cutter body, wherein each cutter tooth consists of a left cutting edge, a right cutting edge, a top edge, a front cutter face, a left rear cutter face, a right rear cutter face and a top rear cutter face; the cutting tool is characterized in that the projections of the left cutting edge and the right cutting edge on the axial section are involutes and are respectively positioned on conjugate surfaces of tooth surfaces of the processed left involute and the processed right involute; the cutting rake angles of all points on the left cutting edge are equal, the cutting rake angles of all points on the right cutting edge are equal, and the cutting rake angle of the left cutting edge is equal to the cutting rake angle of the right cutting edge; the left rear cutter face is a free curved surface formed by a plurality of left cutting edges; the right rear cutter face is a free curved surface formed by a plurality of right cutting edges; the top rear cutter face is a conical face; the top blade is the intersection line of the front blade face and the top rear blade face.

Further, the cutter teeth are straight teeth or inclined teeth.

The rake surface is a free-form surface that makes the cutting rake angle of the left cutting edge and the cutting rake angle of the right cutting edge constant.

Furthermore, the cutting rake angle of the left cutting edge and the right cutting edge is 5-15 degrees.

Further, the left and right cutting edges after resharpening are still on the conjugate plane of the involute flank being machined.

The invention also provides a construction method of the equal cutting rake angle slotting cutter, which comprises the following steps: setting the tooth surface of the processed part in contact with the left cutting edge as an A tooth surface, setting the tooth surface of the processed part in contact with the right cutting edge as a B tooth surface, establishing a conjugate tooth surface model of the A tooth surface of the processed part according to a conjugate principle, selecting part points on the conjugate tooth surface of the A tooth surface of the processed part according to a constraint condition as cutting edge model points, and fitting the model points by using a sample curve to obtain a space curve, wherein the curve is the left cutting edge; and establishing a conjugate tooth surface model of the tooth surface of the part B to be processed, selecting partial points on the conjugate tooth surface of the part B to be processed according to constraint conditions as cutting edge model value points, and fitting the model value points by using a sample curve to obtain a space curve, wherein the curve is a right cutting edge.

Further, changing the displacement coefficient of the conjugate tooth surface of the tooth surface A of the machined part to obtain a series of conjugate tooth surfaces of the tooth surface A of the machined part, further obtaining a series of left cutting edges, and performing curve fitting on the left cutting edges to form a curve surface, namely a left back tool surface; and changing the deflection coefficient of the conjugate tooth surface of the part B to be processed to obtain a series of conjugate tooth surfaces of the tooth surface of the part B to be processed, further obtaining a series of right cutting edges, and performing curved surface fitting on the right cutting edges to form a curved surface, namely a right back cutter surface.

Further, the model value point M on the corresponding left cutting edge _i1,2, 3 … n, establishing a tool cutting angle reference plane comprising a base plane, a cutting plane and an orthogonal plane; let line segment M_iH_iIs located on the intersection line of the orthogonal plane and the base plane, and

the direction of (1) is directed to the right cutting edge side; in orthogonal plane, the over-type value M_iLine segment M_iN_iTo makePointing to the inside of the cutter teeth to make an angle N_iM_iH_iA cutting rake angle equal to the set left main cutting edge; corresponding to the model value point U on the right main cutting edge _i1,2, 3 … n, establishing a tool cutting angle reference plane comprising a base plane, a cutting plane and an orthogonal plane; line segment U_iV_iIs located on the intersection line of the orthogonal plane and the base plane, andthe direction of (a) is directed to the left cutting edge side; in the orthogonal plane, the over-type value point U_iLine segment making U_iW_iTo makePointing to the inside of the cutter teeth to form an angle W_iU_iV_iA cutting rake angle equal to the set right main cutting edge; will M_iN_iCorresponding to U_iW_iIs fitted into a space curve L_iI is 1,2, 3 … n, and then the space curve L is divided into_iFitting a space curved surface, wherein the formed curved surface is the rake face.

The invention has the advantages and positive effects that: according to the slotting cutter, the space curves on the conjugate surfaces of the processed involute tooth surfaces are used as the left cutting edge and the right cutting edge, the front angles of all points on the left cutting edge are equal, the front angles of all points on the right cutting edge are equal, and the front angle of the left cutting edge is equal to that of the right cutting edge, so that the processing surface quality of parts is better, the processing precision is higher, and the processing precision of the left tooth surface and the right tooth surface is consistent; for the tooth surface on the same side, the processing precision before and after the cutter sharpening is consistent, namely constant precision; the left and right cutting edges of the gear shaper cutter are simultaneously cut in and out, and the fluctuation of cutting force is small.

Drawings

Fig. 1 is a schematic structural view of a slotting cutter of the present invention.

Fig. 2 is a schematic view of a cutter tooth structure of the slotting cutter.

Fig. 3 is a conjugate tooth flank mesh division diagram in a method of constructing a slotting cutter of the present invention.

FIG. 4 is a schematic view of the left and right cutting edges of the slotting cutter of the present invention.

Fig. 5 is a schematic diagram of the process of forming the left and right flank surfaces of a slotting cutter according to the present invention.

Figure 6 is a schematic view of a tool cutting angle reference plane of a slotting cutter of the present invention.

Fig. 7 is a schematic view of the rake face forming process of a slotting cutter of the present invention.

In the figure: 1. cutter teeth; 2. a cutter body; 3. a rake face; 4. a top edge; 5. a top flank face; 6. a right rear blade face; 7. a right cutting edge; 8. a left cutting edge; 9. a left flank face.

Detailed Description

In order to further explain the contents, features and effects of the present invention, the following embodiments are described with reference to the accompanying drawings:

referring to fig. 1 to 7, the equal cutting rake angle slotting cutter comprises a cutter body 2 and cutter teeth 1 uniformly distributed along the circumference of the cutter body 2, wherein each cutter tooth 1 consists of a left cutting edge 8, a right cutting edge 7, a top edge 4, a front cutter face 3, a left rear cutter face 9, a right rear cutter face 6 and a top rear cutter face 5; the projections of the left cutting edge 8 and the right cutting edge 7 on the axial section are both involute curves, and the left cutting edge 8 and the right cutting edge 7 are respectively positioned on conjugate surfaces of tooth surfaces of the processed involute curves at the left and the right; the cutting rake angles of the points on the left cutting edge 8 are equal, the cutting rake angles of the points on the right cutting edge 7 are equal, and the cutting rake angle of the left cutting edge 8 is equal to the cutting rake angle of the right cutting edge 7; the rake surface 3 is a free-form surface in which the cutting rake angle of the left cutting edge 8 and the cutting rake angle of the right cutting edge 7 are constant; the left rear cutter face 9 is a free curved surface formed by a plurality of left cutting edges 8; the right rear cutter face 6 is a free curved surface formed by a plurality of right cutting edges 7; the top rear knife face 5 is a conical surface; the top edge 4 is the intersection of the rake face 3 and the top flank face 5.

The diameter of the top circle of the top rear cutter face is gradually reduced from the front end of the cutter to the back to form a top edge rear angle, and the angle of the top edge rear angle can be 3-5 degrees.

Further, the cutter teeth 1 may be straight teeth or helical teeth.

Further, the cutting rake angle of the left cutting edge 8 and the right cutting edge 7 may be 5 to 15 °.

According to the slotting cutter with the equal cutting rake angle, the left cutting edge 8 and the right cutting edge 7 after being sharpened again are still on the conjugate surfaces of the processed involute tooth surfaces.

The invention also provides a method of constructing a rake tooth cutter as described above, the method comprising:

setting the tooth surface of the processed part contacted with the left cutting edge 8 as an A tooth surface, setting the tooth surface of the processed part contacted with the right cutting edge 7 as a B tooth surface, establishing a conjugate tooth surface model of the tooth surface of the processed part A according to a conjugate principle, selecting part points on the conjugate tooth surface of the processed part A according to constraint conditions as cutting edge type value points, and setting X_iThe type value points X are the type value points on the conjugate tooth surface of the part A to be processed, i is 1,2 and 3 … n_iFitting a sample strip curve to obtain a space curve, wherein the curve is the left cutting edge 8; establishing a conjugate tooth surface model of the tooth surface of the processed part B, selecting partial points on the conjugate tooth surface of the processed part B according to constraint conditions as cutting edge type value points, and setting Y_iThe type value points are the type value points on the conjugate tooth surface of the processed part B, i is 1,2 and 3 … n, and the type value points Y_iA space curve is obtained by curve fitting the sample strip, and the curve is the right cutting edge 7.

The constraint condition is set for the smooth and continuous cutting edge curves and moderate curvature of the left cutting edge 8 and the right cutting edge 7, so that the cutting edge curves are in smooth transition, and the saw-toothed shape is avoided.

The constraint condition can adopt the constraint condition in the prior art, and can also adopt the following constraint condition:

(1) setting the absolute value of the difference between the Z coordinates of adjacent type value points as a fixed value; the constraint condition can ensure that the cutting edge curve is smooth and continuous and has moderate curvature.

(2) The frequency of the positive difference between the Z coordinates of the adjacent type value points is 1, and the rest are negative numbers; or the frequency of the negative difference between the Z coordinates of the adjacent type value points is 1, and the rest are positive numbers; the constraint condition can ensure that the cutting edge curve is convex or concave, is in smooth transition and avoids the saw-toothed shape.

Furthermore, the displacement coefficient of the conjugate tooth surface of the processed part A can be changed to obtain a series of conjugate tooth surfaces of the tooth surface of the processed part A, a series of left cutting edges 8 can be further obtained, the left cutting edges 8 can be subjected to surface fitting, and the formed curved surface is the left back tool surface 9; the deflection coefficient of the conjugate tooth surface of the processed part B can be changed to obtain a series of conjugate tooth surfaces of the tooth surface of the processed part B, a series of right cutting edges 7 can be further obtained, the right cutting edges 7 can be subjected to surface fitting, and the formed curved surface is the right back tool surface 6.

Can be provided with x_kFor the displacement coefficient, k is 1,2, 3 … m, and C may be provided_kTo correspond to the shift coefficient x_kK is 1,2, 3 … m; can be provided with E_kTo correspond to the shift coefficient x_kK is 1,2, 3 … m, which is the conjugate tooth surface of the workpiece B. Let D_kTo correspond to conjugate tooth surfaces C_kK 1,2, 3 … m; let F_kTo correspond to conjugate tooth surfaces E_kK is 1,2, 3 … m.

Corresponding to the coefficient of variation x_kAnd k is 1,2 and 3 … m, and a series of conjugate tooth surfaces C of the tooth surface of the part A to be machined are obtained_k K 1,2, 3 … m, a series of left cutting edges D are further obtained_kK is 1,2, 3 … m; these left cutting edges D can be adjusted_kAnd performing surface fitting to form a curved surface which is the left rear cutter face 9.

Similarly, the corresponding shift coefficient x_kK is 1,2 and 3 … m, and a series of conjugate tooth surfaces E of the tooth surfaces of the part B to be processed are obtained_k K 1,2, 3 … m, a series of right cutting edges F are further obtained_kK is 1,2, 3 … m; these right cutting edges F can be adjusted_kAnd performing surface fitting to form a curved surface which is the right rear cutter surface 6.

Furthermore, the model value point M on the left cutting edge can be corresponded_i1,2, 3 … n, establishing a tool cutting angle reference plane comprising a base plane, a cutting plane and an orthogonal plane; can be provided with a line segment M_iH_iIs located on the intersection line of the orthogonal plane and the base plane, andthe direction of (d) is directed toward the right cutting edge 7 side; can be used for passing through a value point M in an orthogonal plane_iLine segment M_iN_iCan makePointing to the inner side of the cutter teeth to make an angle N_iM_iH_iA cutting rake angle equal to the set left main cutting edge; can correspond to the model value point U on the right main cutting edge _i1,2, 3 … n, establishing a tool cutting angle reference plane comprising a base plane, a cutting plane and an orthogonal plane; capable of setting line segment U_iV_iOn the intersection of the orthogonal plane and the base plane, can

Is directed to the left cutting edge 8 side; in the orthogonal plane, the over-type value point U_iLine segment making U_iW_iCan makePointing to the inner side of the cutter teeth to form an angle W_iU_iV_iA cutting rake angle equal to the set right main cutting edge; will M_iN_iCorresponding to U_iW_iIs fitted into a space curve L_iI is 1,2, 3 … n, and then the space curve L is divided into_iFitting a space curved surface, wherein the formed curved surface is the rake face.

The invention will be further illustrated by the following preferred embodiment of the invention.

A slotting cutter with equal cutting rake angles, wherein cutter teeth 1 are oblique teeth, as shown in figure 1, the slotting cutter comprises a cutter body 2 and cutter teeth 1 distributed along the circumference of the cutter body 2, and each cutter tooth 1 consists of a left cutting edge 8, a right cutting edge 7, a top edge 4, a front cutter face 3, a left rear cutter face 9, a right rear cutter face 6 and a top rear cutter face 5; the projections of the left cutting edge 8 and the right cutting edge 7 on the axial section are involutes and are respectively positioned on conjugate surfaces of tooth surfaces of the left involute and the right involute to be processed, the cutting rake angles of all points on the left cutting edge 8 are equal, the cutting rake angles of all points on the right cutting edge 7 are equal, and the cutting rake angle of the left cutting edge 8 is equal to the cutting rake angle of the right cutting edge 7; the left rear cutter face 9 is a free curved surface formed by a plurality of left cutting edges 8; the right rear cutter face 6 is a free curved surface formed by a plurality of right cutting edges 7; the top rear knife face 5 is a conical surface; the top edge 4 is the intersection of the rake face 3 and the top flank face 5.

The left cutting edge 8 and the right cutting edge 7 are constructed as follows:

and setting the tooth surface of the processed part in contact with the left cutting edge 8 as an A tooth surface, setting the tooth surface of the processed part in contact with the right cutting edge 7 as a B tooth surface, and establishing a conjugate tooth surface model of the A tooth surface of the processed part. According to the conjugation principle, generating a conjugate tooth surface of an involute tooth surface to be processed, as shown in fig. 3, wherein M point is any point on the conjugate tooth surface of the tooth surface of a processed part A, the M 'point is convenient for graphic arrangement, the M' point corresponds to the M point, the distances from the M point to a rotation axis are the same, and the rotation angles around the rotation axis are the same. Distance from M point to rotary axis is R_m，R_fRoot circle radius, R_aRadius of addendum circle, R_f≤R_m≤R_a(ii) a Theta is the angle of the M point rotating around the rotation axis, and theta is more than or equal to 0 and less than or equal to 2 pi. That is, the position of any point on the conjugate tooth surface of the A tooth surface is defined by two parameters R_mAnd θ. R is to be_fTo R_aN is equally divided, then R_mIn order of R_f，R_f+Δ，R_f+2Δ……R_f+(n-2)Δ，R_aWherein

Meanwhile, θ is equally divided by m within 0 to 2 π.

Referring to fig. 4, the a tooth surface is divided into an n × m lattice. These points are labeled (1,1) (1,2) … (1, m), (2,1) (2,2) … … (2, m) … … (n,1) (n,2) … (n, m). From these points, 1 point is selected for every m points as a type value point on the left cutting edge 8, and n type value points, i.e., (1, m) are selected in total₁)、(2,m₂)、(3,m₃)、(4,m₄)、……、(n,m_n) The n type value points are fitted with a 3-degree B-spline curve to obtain a spatial curve, which is a left cutting edge 8.

And similarly, establishing a conjugate tooth surface model of the tooth surface of the part B to be processed. The conjugate tooth surface of the B tooth surface can also be divided into a lattice of n m. Selecting n type value points, i.e. (1, y)₁’)、(2,y₂’)、(3,y₃’)、(4,y₄’)、……、(n,y_n') in which any one set of corresponding points (n, m) on the left and right cutting edges 7_n) And (n, y)_n') should the Z coordinates be equal, fitting the n type value points with a 3-fold B-spline curve yields a space curve, which is the right cutting edge 7.

Referring to fig. 5, the deflection coefficient of the conjugate tooth surface is changed to obtain a series of left and right conjugate tooth surfaces, and the edge selecting process is repeated to obtain a series of left cutting edges 8S_a1、S_a2、S_a3、S_a4、S_a5… …, and a series of right cutting edges 7S_b1、S_b2、S_b3、S_b4、S_b5… …, respectively; the left cutting edge 8 and the right cutting edge 7 are subjected to surface fitting respectively to obtain a left cutter flank 9 and a right cutter flank 6 of the gear shaping with equal cutting rake angles.

The rake face 3 is constructed as follows:

referring to FIG. 6, the model point M on the left major cutting edge is shown_iAnd i is 1,2 and 3 … n, and a tool cutting angle reference plane including a base plane, a cutting plane and an orthogonal plane is established. The helical gear shaping motion is synthesized by the up-and-down cutting motion and the rotary indexing motion, the additional rotation is ignored, the velocity vector v is obtained through calculation, and the direction of the base plane normal vector is the same as the direction of the velocity vector v. According to the metal cutting principle, a cutting plane normal vector and an orthogonal plane normal vector are determined. Thus, the tool cutting angle reference plane is also determined. Passing through a model value point M on the left main cutting edge₁Establishing the reference plane of the cutting angle of the tool at that point, P_rIs a basal plane, P_sTo cut a plane, P_OBeing orthogonal planes, M₁H₁Is the intersection of the orthogonal plane and the base plane. In the orthogonal plane, passing through point M₁Line segment M₁N₁Line segment M₁N₁And the straight line M₁H₁The included acute angle is a cutting rake angle of the pinion cutter and the like. As shown in fig. 6, a series of model points M on the left main cutting flank are crossed according to the requirement of equal cutting rake angle₁、M₂、M₃、M₄… … A series of line segments M may be constructed₁N₁、M₂N₂、M₃N₃、M₄N₄… …, respectively; similarly, a series of model value points U on the right main cutting edge₁、U₂、U₃、U₄… …, set U₁V₁The intersection of the orthogonal plane and the base plane, a series of line segments U can be constructed₁W₁、U₂W₂、U₃W₃、U₄W₄… … are provided. A plurality of straight line segments M corresponding to the left main cutting edge and the right main cutting edge₁N₁And U₁W₁，M₂N₂And U₂W₂，M₃N₃And U₃W₃… …, fitting into a space curve L₁,L₂,L₃… …, respectively; these spatial curves are then fitted with cubic B-splines to form the rake face 3 in the form of a free-form surface.

The above-mentioned embodiments are only for illustrating the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to carry out the same, and the present invention shall not be limited to the embodiments, i.e. the equivalent changes or modifications made within the spirit of the present invention shall fall within the scope of the present invention.