CN214212484U

CN214212484U - A cut tooth cutter for cycloid wheel processing

Info

Publication number: CN214212484U
Application number: CN202023315996.5U
Authority: CN
Inventors: 王鹏; 刘福聪; 李敬财; 满佳
Original assignee: Tianjin University of Technology and Education China Vocational Training Instructor Training Center
Current assignee: Tianjin University of Technology and Education China Vocational Training Instructor Training Center
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2021-09-17
Anticipated expiration: 2030-12-31

Abstract

The utility model discloses a tooth cutting tool for processing a cycloid gear, which comprises a tool body and a plurality of tool teeth evenly distributed along the circumference of the tool body, wherein each tool tooth comprises a front tool face, a rear tool face and a cutting edge; the rake face is a curved surface; the cutting edge is a conjugate line of the tooth surface of the cycloidal gear to be processed, and working rake angles at any point on the cutting edge are equal; the flank face is a curved face composed of a plurality of cutting edges. The rake angles of all points of the cutting edge of the tooth cutting tool are consistent when the cutting edge participates in cutting, so that the tooth surface processing quality can be effectively improved, and the vibration of a machine tool is reduced.

Description

A cut tooth cutter for cycloid wheel processing

Technical Field

The utility model relates to a machining design technical field especially relates to a cut tooth cutter to pieces for cycloid wheel processing.

Background

With the continuous improvement of the automation level of China industry, the quality requirement on the RV reducer is higher and higher, and the demand is larger and larger. The market is basically monopolized by foreign companies because the mass production process of the RV reducer is not mastered in China.

The cycloid wheel is one of the most critical parts in the RV reducer, and the manufacturing precision of the cycloid wheel is crucial to the precision index of the reducer. At present, the processing of the tooth surface of the cycloidal gear generally uses a forming and grinding process, the process adopts an intermittent indexing method, the indexing precision is not easy to control, and the process needs to depend on high-precision equipment with high manufacturing cost. Obviously, this method does not meet the requirements for mass production of RV reducers.

The method for machining the cutting teeth has the machining characteristic of continuous indexing, is high in efficiency, energy-saving and environment-friendly, and has more advantages in the aspect of machining the tooth form of the cycloid wheel. In a tooth cutting process system, a tooth cutting knife is one of important factors. At present, the rake face of the tooth cutting knife is basically in a spherical or conical shape, so that the working rake angles at all points of a cutting edge are inconsistent, and the working rake angles of partial blade segments are unreasonable. When the cutter is used for cutting teeth, the vibration of a machine tool is obvious, and the processing quality of the tooth surface is uneven. Therefore, in order to promote the wide application of the tooth cutting technology, in particular to the application of the pushing tooth cutting technology in the machining field of key parts of the RV reducer, the development of a new tooth cutting tool design method is necessary.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a cut tooth cutter to pieces for cycloid wheel processing to current cut tooth cutter to pieces because structural reason causes the lathe to shimmy obviously, the technical defect that flank of tooth processingquality is inhomogeneous.

For realizing the utility model discloses a technical scheme that the purpose adopted is:

a tooth cutting tool for machining a cycloid gear comprises a tool body and a plurality of tool teeth which are uniformly distributed along the circumference of the tool body, wherein each tool tooth comprises a front tool face, a rear tool face and a cutting edge; the rake face is a curved surface; the cutting edge is a conjugate line of the tooth surface of the cycloidal gear to be processed, and working rake angles at any point on the cutting edge are equal; the flank face is a curved face composed of a plurality of cutting edges.

In the technical scheme, the cutter teeth are helical teeth, the rotating direction is left-handed or right-handed, and the helical angle of the cutter teeth is 15-25 degrees, preferably 20 degrees.

In the above technical solution, the working rake angle is 8-20 °, preferably 15 °.

In the technical scheme, the diameter of the top circle of the rear cutter face is gradually reduced from the front end to the rear end of the tooth cutting cutter, and the design relief angle of the rear cutter face is 6-15 degrees, preferably 10 degrees.

Compared with the prior art, the beneficial effects of the utility model are that:

1. the utility model provides an use the piece serrated knife that the design method designed, its cutting edge each point is unanimous at the working rake angle when participating in the cutting, can effectively improve the flank of tooth processingquality, reduces the lathe and trembles.

2. Use the utility model provides a piece serrated knife that cuts that design method designed need not to use high accuracy equipment in the cycloid wheel course of working, compares with other cycloid wheel processing methods, and this method is efficient, with low costs.

3. The utility model provides a design method has added the verification step, utilizes the cutter angle reference system of establishing, calculates the work relief angle, verifies the feasibility of design relief angle, further increases the feasibility of cutter design.

Drawings

Fig. 1 is a schematic view of machining of a cutting tooth of a cycloid gear;

FIG. 2 is a tool design calculation coordinate system;

FIG. 3 is a schematic of a tool angular coordinate system and rake face configuration;

FIG. 4 is a schematic of a design relief angle and flank configuration;

FIG. 5 is a schematic representation of the working relief angle calculation;

FIG. 6 is an exemplary embodiment of the working relief angle at 50 points on the primary cutting edge;

fig. 7 is a flow chart of a design method of a cycloid wheel tooth cutting knife with equal rake angle.

FIG. 8 is a schematic view of the conjugate relationship between the tooth surface of the cycloidal gear and the cutting edge;

wherein, a is a side view and b is a top view.

The machining tool comprises a tool body 1, a tool tooth 2, a front tool face 21, a rear tool face 22, a cutting edge 23, a cycloidal gear to be machined 3, a cycloidal gear tooth face 4 and a conjugate contact point 5.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

A tooth cutting tool for machining a cycloid gear comprises a tool body 1 and a plurality of cutter teeth 2 uniformly distributed along the circumference of the tool body 1, wherein each cutter tooth 2 comprises a front cutter face 21, a rear cutter face 22 and a cutting edge 23; the rake face 21 is a curved surface; the cutting edge 23 is a conjugate line of the tooth surface of the cycloidal gear 3 to be processed, and working rake angles at any point on the cutting edge 23 are all equal; the flank surface 22 is a curved surface formed by a plurality of the cutting edges. The rear tool faces of every two adjacent cutter teeth 2 are in smooth transition. The cutter teeth 2 are helical teeth, and the helical angle of the left-handed cutter teeth 2 is 20 degrees. The working rake angle is 15 °. The diameter of the top circle of the rear tool face 22 is gradually reduced from the front end to the rear end of the tooth cutting tool, and the design relief angle of the rear tool face is 10 degrees.

In practical application, according to different workpiece sizes and machine tool performance requirements, the working rake angle is changed to 8-20 degrees, or the design relief angle of the rear cutter face is changed to 6-15 degrees, or the right rotation of the cutter tooth and the helix angle are changed to 15-25 degrees, so that the overall performance of the tooth cutting cutter is not affected.

Example 2

A design method of a tooth cutting tool for machining a cycloid gear comprises the following steps:

step 1: establishing a coordinate system for use in a design method

In the process of cutting teeth, the position relation and the motion relation between a workpiece to be machined (namely a cycloid wheel) and a cutter (namely a cutting tooth cutter to be designed) are shown in fig. 1, a certain included angle exists between the axis of the workpiece and the axis of the cutter, the cutter and the workpiece rotate synchronously at high speed, the workpiece is fed along the axis of the workpiece, and the machining of the whole tooth surface of the workpiece is completed.

Three coordinate systems, i.e., a workpiece coordinate system S1, a tool coordinate system S2, and an auxiliary coordinate system Sp, are established based on the positional relationship and the kinematic relationship between the workpiece and the tool shown in fig. 1, as shown in fig. 2. Wherein z of the object coordinate system S1₁The axis coinciding with the workpiece axis, x₁o₁y₁The plane is superposed with the lower end face of the workpiece and rotates along with the workpiece. Z of tool coordinate system S2₂The axis coinciding with the tool axis, x₂o₂y₂The plane is superposed with the upper end face of the cutter and rotates along with the cutter. The auxiliary coordinate system Sp is a spatially fixed coordinate system corresponding to the initial positions, x, of the workpiece coordinate system S1 and the tool coordinate system S2_pAxis coincident with x-axis, z_pThe included angle between the axis and the z axis is the intersection angle gamma, z_pThe distance between the axis and the z-axis is the axial distance a between the workpiece and the cutter.

Step 2: MATLAB software is applied to establish a mathematical model of the tooth surface of the cycloidal gear in a workpiece coordinate system S1

The parameters of the workpiece to be machined are shown in table 1,

from the parameters provided in table 1, the mathematical model of the cycloidal tooth surfaces in the workpiece coordinate system S1 is as follows:

in the above-mentioned formula, the compound of formula,

the coefficient is a tooth-shaped short amplitude coefficient when the distance is shifted and the shape is corrected;

a is the eccentricity between the rolling circle and the base circle;

Z_p,Z_cthe number of teeth of the pin wheel and the number of teeth of the cycloid wheel are respectively;

r_pthe radius of the circle, Δ r, being distributed to the pinwheel_pIs the displacement modification amount;

r_rpis the pinwheel radius, Δ r_rpEqual-distance modification quantity;

delta is the corner modification amount;

and h is the independent variable of the parameter equation of the cycloid wheel,

the turning angle of the rotating arm relative to the center radius of a certain pin during the formation of the tooth surface of the cycloidal gear is shown; h is a height parameter and has a value range of [0, H]。

And step 3: obtaining a mathematical model of the conjugate plane in the tool coordinate system S2

Firstly, the initial axle center distance between the workpiece and the cutter is calculated according to the following formula,

wherein r is_baThe radius of the addendum circle of the cycloidal gear is the maximum distance from a point on the tooth surface of the cycloidal gear to the axis of the cycloidal gear; r is_bfThe radius of a tooth root circle of the cycloidal gear is the minimum distance from a point on the tooth surface of the cycloidal gear to the axis of the cycloidal gear; z_dNumber of teeth of tool, Z_cThe number of teeth of the cycloid gear is shown.

Then, on the basis of the parameters, the motion speed v of the M1 relative to the conjugate point M2 of the cycloidal gear tooth surface at the time of conjugate contact is obtained through derivation according to the position and motion relation between any point (represented by M1) on the cycloidal gear tooth surface and the conjugate point (represented by M2) obtained in the step 2₁₂The mathematical model of (2):

v₁₂＝v_xi+v_yj+v_zk (3)

wherein,

ω₁、ω₂the angular speeds of the workpiece and the cutter rotating around the axes of the workpiece and the cutter are respectively;

indicating the angle the workpiece has rotated relative to the initial position;

(x₁,y₁,z₁) Coordinates of the conjugate contact point in the workpiece coordinate system S1;

a is the axial distance between the workpiece and the tool, where a is a₀；

v is the feed rate, is composed of

Obtaining the unit mm/s, wherein f represents the given feeding amount;

l is the distance of feeding the workpiece along the axis of the workpiece relative to the initial position when M1 point conjugate contact exists, and the following relations exist:

according to the curved surface conjugation principle, the normal vector and the relative movement speed of the tooth surface of the cycloidal gear meet the following relationship:

N_b·v₁₂＝0 (4)

wherein N is_bThe normal vector of the tooth surface of the cycloidal gear obtained in the step 2 at a certain point is obtained. In equation (4) only

For the unknowns, solving the equation yields

From the condition that a certain point on the tooth surface of the cycloid wheel coincides with a corresponding point on the conjugate plane at the time of conjugate contact, a mathematical model of the conjugate plane in the tool coordinate system S2 can be obtained:

wherein,

for the angle of rotation of the tool relative to the initial position, by

And (4) obtaining.

(x₁,y₁,z₁) The coordinates of the conjugate contact point in coordinate system S1.

And 4, step 4: mathematical model for obtaining cutting edge and movement speed of any point on the cutting edge relative to tooth surface of cycloidal gear

Considering the characteristic that the tooth profile of the cycloidal gear is a complete curve, selecting the conjugate line of the end face tooth profile of the cycloidal gear as a cutting edge on the conjugate plane obtained in the step 3, namely setting the variable h in the formula (1) in the step 2 as a constant, obtaining the cutting edge, and recording the variable as (x)_r,y_r,z_r)。

The motion speed v of any point M1 on the cycloidal gear tooth surface obtained in the step 3 relative to the conjugate point M2 of the cycloidal gear tooth surface when in conjugate contact₁₂The mathematical model of (2) is obtained as a mathematical model of the speed of movement of any point on the cutting edge relative to the tooth surface of the cycloidal gear, i.e. a commonThe inverse vector of the vector shown in formula (3), v_e＝-v₁₂。

And 5: mathematical model for obtaining rake face

And (4) establishing a tool angle reference system according to the tangent vector at any point on the cutting edge obtained in the step (4) and the movement speed of any point on the cutting edge relative to the tooth surface of the cycloidal gear. As shown in FIG. 3, the plane perpendicular to the direction of relative motion is the base plane P_rThe plane defined by the cutting edge's tangent and relative speed of movement being the cutting plane P_sWith the base plane P_rAnd a cutting plane P_sTwo-by-two perpendicular planes as main section plane P_o. According to the metal cutting theory, the rake angle is defined as the main profile P_oThe angle between two inner straight lines, which are the base plane P_rAnd the main profile P_oCross line and main profile P_oTangent line of the intersection line of the rake face. As shown in fig. 3, the base surface P_rAnd the main profile P_oIs N1, and a rake angle of 8 DEG is set at the main section plane P_oIn the inner, a straight line tr is constructed so as to be parallel to the straight line N₁Is equal to 8 deg., will straight line t_rAs a line of construction of the rake face. Considering the requirement of the precision of the curved surface construction, the straight line t is constructed at 100 points on the cutting edge_rAnd at each straight line t_rAnd determining 20 discrete points within the range of the upper 5mm, and obtaining coordinate data of 2000 points which are the type value points. And then constructing a cubic B-spline surface to enable the cubic B-spline surface to pass through the type value points in an interpolation mode, wherein the constructed surface is the rake face, and a mathematical model of the cubic B-spline surface is as follows:

wherein mu and omega are two parameters of the parameter equation; n is a radical of_i,3(u)、N_j,3(w) is a cubic B-spline basis function;

P_i,jcontrol points representing the rake face are obtained by reverse solving of rake face type value points according to the cubic B-spline interpolation construction principle (reference: Zhuxinxiong, freeform curve surface modeling technique, Beijing, science Press 2000 (IS)BN 9787030074409))。

Step 6: mathematical model for obtaining flank face

In order to ensure the retention of the machining accuracy after the tool regrinding, the flank face is constructed by a reground cutting edge. In order to construct the tool relief angle, the radius of the addendum circle of the reground cutting edge should be reduced, and the axial distance between the workpiece and the tool is reduced during corresponding machining. Using the cutting edge obtained in the step 4 as an initial cutting edge r₁The addendum point of which is taken as the investigation point and at this point along the initial conjugate plane c₁Tooth direction of the tooth is set up to design back angle reference plane P_α. As shown in fig. 4, in the reference plane, according to a given design relief angle α_dDetermining the relationship between the axle center distance variation delta a and the tooth crest point grinding quantity delta g after regrinding:

wherein alpha is_dDesigning a relief angle for the tool;

delta a is the variation of the axle center distance after each regrinding;

Δ g is the amount of change in the location of the crest of the cutting edge after each regrinding.

Determining the regrinding times of the cutter to be 10 according to the requirement of the service life of the cutter, setting the variation of the addendum point position of a regrinding cutting edge to be 0.6mm each time, preliminarily setting the design relief angle to be 6 degrees, calculating the variation delta a of the axle center distance after regrinding each time according to a formula (7), and combining the initial axle center distance alpha between the workpiece and the cutter calculated in the step 3₀Obtaining the axle center distance a after regrinding₀Δ a, repeating the subsequent steps of step 3 to obtain a reground conjugate plane c₂Then according to the method of step 4, the conjugated surface c after regrinding is determined according to Δ g₂Upper determination curve r₂As reground cutting edges r₂. Determining the conjugate surface c after repeated grinding₃， c₄… …, and reground cutting edge r₂，r₃，r₄… … are provided. Uniformly dispersing 100 cutting edges on each cutting edge (including the initial cutting edge and the reground cutting edge)And (4) obtaining coordinate data of 1100 points which are the type value points of the flank face. And then constructing a cubic B-spline surface to enable the cubic B-spline surface to pass through all the model value points in an interpolation mode, wherein the constructed surface is a rear cutter face, and a mathematical model of the cubic B-spline surface is as follows:

wherein m and n are parameters of the parameter equation; n is a radical of_i,3(m)、N_j,3(n) is a cubic B-spline basis function;

Q_i,jand the control points represent the flank surfaces, and are obtained by reversely solving flank surface type value points according to a cubic B-spline interpolation construction principle.

And 7: verifying feasibility of design relief angle

The utility model discloses in, the design of rake face can guarantee that the working rake angle of each point department of cutting edge all is unanimous with the setting value. However, the design of the relief surface takes the design clearance as a parameter, and the working clearance at each point of the cutting edge cannot be guaranteed to be consistent. For this purpose, the tool angle reference system established in step 5 is used for calculating the working clearance angle and verifying the feasibility of designing the clearance angle.

As shown in FIG. 5, the working relief angle is the angle between two straight lines in the main section, which are the cutting planes P_sAnd the main profile P_oThe unit direction vectors of the intersection line of (A) and the tangent line of the intersection line of the flank face and the main cross section are respectively represented as N₂,t_αWherein

N₂＝N₁×N_o (9)

wherein N is₁Is a main section P_oAnd a base plane P_rThe unit direction vector of the intersection line of (a);

N_ois the unit direction vector of the intersection line of the cutting plane and the base plane.

Calculating the unit normal vector N of the flank face at each point of the initial cutting edge according to the formula (8)_hThen N is_h⊥t_αWhile N is present_o⊥t_αThe following can be obtained:

t_α＝N_h×N_o (10)

the working relief angle at each point of the cutting edge is calculated by:

in this embodiment, the working relief angle at 50 points on the initial cutting edge is calculated as shown in fig. 6. From the calculation results, the minimum working clearance angle is 4.1 ° and the maximum working clearance angle is 6 °, indicating that the tool has a significant working clearance angle, thereby effectively avoiding interference, and therefore, it is feasible to determine the design clearance angle to be 6 °.

And 8: obtaining a three-dimensional model of equal-rake tooth cutting knives

And (4) establishing a three-dimensional model of the equal rake angle tooth cutting tool according to the mathematical model of the cutting edge obtained in the step (4), the mathematical model of the front tool face obtained in the step (5) and the mathematical model of the rear tool face obtained in the step (6).

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The utility model provides a cut a piece tooth cutter for processing of cycloid wheel which characterized in that: the cutter comprises a cutter body and a plurality of cutter teeth which are uniformly distributed along the circumference of the cutter body, wherein each cutter tooth comprises a front cutter face, a rear cutter face and a cutting edge; the rake face is a curved surface; the cutting edge is a conjugate line of the tooth surface of the cycloidal gear to be processed, and working rake angles at any point on the cutting edge are equal; the flank face is a curved face composed of a plurality of cutting edges.

2. The cutting tooth tool for machining the cycloid wheel as claimed in claim 1, characterized in that: the cutter teeth are helical teeth.

3. The cutting tooth tool for machining the cycloid wheel as claimed in claim 2, characterized in that: the rotary direction of the cutter teeth is left-handed or right-handed.

4. The cutting tooth tool for machining the cycloid wheel as claimed in claim 3, characterized in that: the helix angle of the cutter teeth is 15-25 degrees.

5. The cutting tooth tool for machining the cycloid wheel as claimed in claim 4, characterized in that: the helical angle of the cutter teeth is 20 degrees.

6. The cutting tooth tool for machining the cycloid wheel as claimed in claim 1, characterized in that: the working rake angle is 8-20 degrees.

7. The cutting tooth tool for machining the cycloid wheel as claimed in claim 6, characterized in that: the working rake angle is 15 °.

8. The cutting tooth tool for machining the cycloid wheel as claimed in claim 1, characterized in that: the diameter of the top circle of the rear cutter face is gradually reduced from the front end to the rear end of the tooth cutting cutter.

9. The cutting tooth tool for machining the cycloid wheel as claimed in claim 8, characterized in that: the tooth crest clearance angle of the rear cutter face is 6-15 degrees.

10. The cutting tooth tool for machining the cycloid wheel as claimed in claim 9, characterized in that: the tooth crest clearance angle of the rear cutter face is 10 degrees.