A kind of design method of serration gear hobbing cutter
Technical field
The present invention relates to a kind of design method of serration gear hobbing cutter, belongs to automobile power steering gear assembly steering arm shaft
Serration processing technique field.
Background technology
Steering arm shaft serration in existing automobile power steering gear assembly(See Fig. 1), it is to use gear hobbing round tool
(See figure two)Tooth form is processed.Being cut due to hobbing is processed with generating, and the lateral tooth flank of serration tooth form two is faced directly again, such as
For fruit in theory with simulation is transformed into, the tool-tooth profile drawn should be involute curve.But current traditional gear hobbing cutter tooth form is to use
Circular arc line approximation involute curve, the workpiece tooth form that this tool sharpening goes out just are similar to face directly, for serration angle essence
Spend less demanding(Angle precision is at ± 2 °)Workpiece tooth form, requirement can be met;But it can not meet angle ±
The high tolerance requirement of 0.2 ° of workpiece tooth form.
The content of the invention
It is an object of the invention to:A kind of design method of serration gear hobbing cutter is provided, produced by this method
Serration gear hobbing cutter can replace the arc toothed cutter of tradition, serration angle precision be effectively improved, so as to meet workpiece
The high tolerance requirement of tooth form.
The present invention is achieved by the following technical solution:
A kind of design method of serration gear hobbing cutter, it is characterised in that it comprises the following steps:
1), first by rack and pinion engage line method, obtain conjugation tool-tooth profile;
2), establish XOY coordinate systems;Using workpiece tooth form vertex of surface as meshing point(That is O points), XOY coordinate systems are established,
3), draw tooth form circle, workpiece tooth form be rectilinear triangle, is cut in the circle of teeth outline by workpiece centre O1 pictures, the circle is
Tooth form is justified, its radius r=R*sin γ.(Wherein:R is tooth radius, folders of the γ between gear centre line and tooth form extension line
Angle.)
4), draw engagement null circle;Using workpiece centre O1 as the center of circle, radius is that R draws engagement null circle(That is outside circle), that is, mistake
Meshing point O(That is the origin of coordinates).
5), meshing point circular division;On engagement null circle, from meshing point O(That is the origin of coordinates)Rise, intercept some equal circles
Arc, indexed, and the n of invocation point 1,2,3,4 ....
6), draw tooth form circle tangent line.Draw the tangent line of tooth form circle respectively by some n of meshing point circular division point 1,2,3,4 ....
Thus draw the continuous rotation position of workpiece tooth form.
7), do vertical line(That is normal).Because common normal of the conjugate tooth profile at contact point has to pass through node O(Sit
Mark origin).So vertical line can be done to the workpiece tooth form circle tangent line of diverse location by crossing O points(Do normal), with corresponding work
Part tooth form circle tangent line intersects at 1 ', 2 ', 3 ', 4 ' ..., and n ', n ' are positive integer.
8), index in X-axis;Along ent a is intercepted in X-axis1、a2、a3、a4……an;anFor positive integer;Make
9), replicate vertical line;Respectively by line segment O1 ', O2 ', O3 ', O4 ' ... O n ';Replicate and point a on OX axles1、a2、a3、
a4……anIt is intersecting, draw line segment a1a1′、a2a2′、a3a3′、a4a4′……anan′;
10), draw conjugation cutter involute curve;Tie point a1′、a2′、a3′、a4′……an' draw and workpiece conjugation cutter
Involute curve;
11), obtain cutter normal tooth profile;According to the reference diameter of workpiece, tooth pitch, height of teeth top, height of teeth root and design
Tool-tooth profile;
12), simplation verification:Above tooth form is carried out to computer simulation processing again to verify the correctness of tool-tooth profile;
13), tool sharpening:By OX reference axis, tool-tooth profile a can be calculated1′、a2′、a3′、a4′……an' each
The coordinate value of coordinate points;Tooth form can be drawn out by coordinate value;By tool-tooth profile a little coordinate value input numerical control add
In work machine tool program, you can process the serration gear hobbing cutter for the high tolerance requirement for meeting workpiece tooth form.
The beneficial effect of the present invention compared with prior art is:
The present invention obtains cutter normal direction conjugate tooth profile, so as to replace tradition arc toothed using rack and pinion engagement method.
For large-scale, high-precision serration tooth form, the machining accuracy of workpiece tooth form can be substantially improved.
Brief description of the drawings
Fig. 1 is the schematic diagram of steering arm shaft serration;
Fig. 2 is the tooth form schematic diagram of gear hobbing round tool;
Fig. 3 is the gear hobbing cutter tooth form schematic diagram of serration of the present invention;
Fig. 4 is enlarged diagram at Fig. 3 A;
Fig. 5 establishes XOY coordinate system figures;
Fig. 6 is tooth form circle diagram;
Fig. 7 is meshing point circle diagram;
Fig. 8 is meshing point circular division figure;
Fig. 9 is that tooth form justifies tangent line figure;
Figure 10 is vertical line charting;
Figure 11 is that figure is indexed in X-axis;
Figure 12 is duplication vertical line charting;
Figure 13 is cutter involute curve figure;
Figure 14 is cutter normal tooth profile figure;
Figure 15 is the workpieces processing simulation drawing of tool-tooth profile.
Embodiment
Line method is engaged by rack and pinion first, obtains conjugation tool-tooth profile(Referring to accompanying drawing 3,4);Establish XOY seats
Mark system;Using workpiece tooth form vertex of surface as meshing point(That is O points), establish XOY coordinate systems(Referring to accompanying drawing 5);Draw tooth form circle, workpiece tooth
Shape is rectilinear triangle, and the circle for being cut in teeth outline is drawn by workpiece centre O1, and the circle is justified for tooth form, its radius r=R*sin γ(Referring to
Accompanying drawing 6).Using workpiece centre O1 as the center of circle, radius is that R draws engagement null circle, i.e. outside circle, that is, crosses meshing point O(I.e. coordinate is former
Point)(Referring to accompanying drawing 7).
Meshing point circular division is on engagement null circle, from meshing point O, intercepts some equal circular arc line segments, is indexed,
And the n of invocation point 1,2,3,4 ...;N is positive integer(Referring to accompanying drawing 8).
Draw tooth form circle tangent line;Draw the tangent line of tooth form circle respectively by some n of meshing point circular division point 1,2,3,4 ...;
Go out the continuous rotation position of workpiece tooth form(Referring to accompanying drawing 9).
Because common normal of the conjugate tooth profile at contact point has to pass through node O(That is the origin of coordinates), can be with so crossing O points
Vertical line is done to the workpiece tooth form circle tangent line of diverse location(Do normal), 1 ' is intersected at corresponding workpiece tooth form circle tangent line,
2′、3′、4′……n′;N ' is positive integer(Referring to accompanying drawing 10);
Indexed in X-axis;Along ent a is intercepted in X-axis1、a2、a3、a4……an;anFor positive integer;Make
(Referring to accompanying drawing 11).
Respectively by line segment O1 ', O2 ', O3 ', O4 ' ... O n ';Replicate and point a on OX axles1、a2、a3、a4……anIt is intersecting, obtain
Go out line segment a1a1′、a2a2′、a3a3′、a4a4′……anan′;(Referring to accompanying drawing 12).
Tie point a1′、a2′、a3′、a4′……an' draw and workpiece conjugation cutter involute curve(Referring to accompanying drawing 13);
According to the reference diameter of workpiece, tooth pitch, height of teeth top, height of teeth root and design tool-tooth profile(Referring to accompanying drawing 14).
Above tooth form is carried out to computer simulation processing again to verify the correctness of tool-tooth profile(Referring to accompanying drawing 15).
By OX reference axis, tool-tooth profile a can be calculated1′、a2′、a3′、a4′……anThe coordinate of ' each coordinate points
Value;Tooth form can be drawn out by coordinate value;By tool-tooth profile a little coordinate value input numerical control machine tool program in,
The serration gear hobbing cutter for the high tolerance requirement for meeting workpiece tooth form can be processed.