JPS63229222A - Grinding method for sector gear - Google Patents

Abstract

PURPOSE:To sharply decrease the ratio of an idling time to the entire grinding time so as to improve grinding efficiency by making the rotational range of a sector gear a little larger than the entire range where a tooth surface of this gear and a rack- shaped grinding surface contact and engage with each other. CONSTITUTION:An emery wheel 30 has plural circular projections 32 along the circumferential direction on its periphery and forms a grinding face 31 whose sectional view is rack-shape at this peripheral face. An emery wheel 30 is shifted in the rotational axis direction (right direction) synchronously with the rotation of a sector gear G in the clockwise direction, so that this grinding face 31 may contact and engage with the tooth surface TS of the sector gear G being substance to be ground in rotation at the circumference of that axis, by controlling each motor by an instruction signal from an electronic controller, so as to create, through grind processing, a tooth surface TS of the sector gear G with this grinding face 31. Then, the rotation range of the sector gear G for grinding is made a little larger than the entire range where the tooth surface TS and the grinding face 31 contact and engage with each other so as to decrease the ratio of an idling time to the entire grinding time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sector gear grinding method for grinding the tooth surface of a sector gear using a rotating grinding wheel.

[Prior art]

In the conventional sector gear grinding method of this type, for example, as shown in FIG. The grinding wheel 1 continuously rotates in one direction in synchronization with the rotation of the sector gear G, and the grinding wheel 1 gives a predetermined depth of cut to the sector gear G and moves the sector gear G in the axial direction. The tooth surface TS of the tooth T that has been subjected to surface hardening treatment is being ground.

[Problem that the invention seeks to solve]

Since the teeth of the sector gear are formed only on a part of the outer periphery, the dry grinding time (grinding wheel However, the ratio of the time during which the tooth surface is not ground becomes large, resulting in a problem that the grinding efficiency is poor and the total grinding time increases. The present invention attempts to solve such problems.

[Means for solving problems]

For this purpose, the sector gear grinding method according to the present invention includes the first
As shown in FIG. 2 and FIG. 2, in the sector gear grinding method of grinding the tooth surface TS of the sector gear G with a rotating grinding wheel, the sector gear G is rotated about its axis, and the grinding wheel 30 is attached with a circumference on its outer periphery. A plurality of annular protrusions 32 are provided along the direction, and the outer peripheral surface thereof forms a grinding surface 31 having a rack-shaped cross section, and the rotation is such that this grinding surface 31 meshes with the tooth surface TS of the sector gear G. It is characterized in that it is moved synchronously in the direction of its rotational axis, and the range of rotation and movement is somewhat larger than the entire range in which the tooth surface TS and the grinding surface 31 mesh.

[Action and effect]

The rotating grinding wheel 30 moves in the direction of its rotational axis in synchronization with the rotation of the sector gear G, and generates and grinds the tooth surface of the sector gear G with a grinding surface 31 having a rack-shaped cross section.

Therefore, it is sufficient that the rotation range of the sector gear G for this grinding is slightly larger than the entire range where the tooth surface and the grinding surface engage and contact each other, and as a result, the ratio of the dry grinding time to the total grinding time can be wide The grinding efficiency is improved and the total grinding time can be shortened.

〔Example〕

The present invention will be explained below with reference to embodiments shown in FIGS. 1 and 2.

FIG. 2 is an overall side view of a sector gear grinding device embodying the present invention. The workpiece to be machined in this example is a sector shaft S to which a pitman arm of an automobile steering system is attached at one end, and a sector gear G integrally formed in the middle part of the sector gear G is a tooth trace of its teeth T. This is a Taber sector gear whose direction intersects the axis of the safety shaft S.

As shown in FIG. 2, a grinding wheel is mounted on a fixed table 11 provided on the left side of the ped 10 through a vertical feed table 15 and a horizontal feed table 16 so as to be able to reciprocate in the horizontal X and Y directions orthogonal to each other. 17, and a column 12 erected and fixed on the right side of the bed has a lifting platform 2 that supports the sector shaft S.
0 is provided so that it can be raised and lowered in two vertical directions.

The vertical feed table 15, which is guided and supported by the fixed table 11 so as to be movable in the X direction (left and right direction in FIG. 2), has a nut 15a fixed to its lower side and a feed screw 16 screwed into the nut 15a.
The horizontal feed table 16 is given reciprocating movement by the vertical feed motor 18 via a, and is guided and supported on the vertical feed table 15 so as to be movable in the Y direction (in the direction perpendicular to the paper plane in FIG. 2).
Reciprocating movement is provided by a transverse feed motor 19 via a similar nut and feed screw. Horizontal feed table 1
A grinding wheel 30 is rotatably supported on a grinding wheel head 17 fixed on a grinding wheel head 17 via a grinding wheel shaft 35 parallel to the Y direction (see Fig. 1), and is rotationally driven in the Ω direction by a grinding wheel drive motor 36. ing. As shown in FIG. 1, a plurality of annular protrusions 32 having a trapezoidal cross-section are provided along the circumferential direction on the outer periphery of the grinding wheel 30, and a grinding surface 31 having a rack-shaped cross-section is formed by the surface thereof.

As shown in FIG. 2, a lifting platform 20 is guided and supported on the column 12 so as to be movable up and down in the vertical Z direction, and a lifting platform 20 is guided and supported on the column 12 via a Nando 20a fixed to the negative side and a feed screw 21 screwed thereto. The vertical movement is given by the vertical movement feed motor 21.

On one side 20a of the lifting table 20 facing the whetstone table 17,
A headstock 22 supporting the main shaft 24 and a center support 25 supporting the center 26 are coaxially opposed to each other, and the direction of their common central axis 0 is perpendicular to the Y direction. The main shaft 24 is given reciprocating rotation in the ω direction by the main shaft drive motor 23, and a chuck 24a is provided at its tip on the side of the Shinshindai 25.

The sector shaft S, which has the sector gear G to be ground integrally formed in the middle part, is held at one end by a chuck 24a so as to be in a predetermined phase with respect to the main shaft 24, and the other end is held at the center 24.
6 and reciprocates together with the main shaft 24. In a state where the sector shaft S is supported by the lifting platform 20,
The central axis O is inclined with respect to the Z direction so that the tooth trace direction of the teeth T of the sector gear G on a plane including the central axis O and orthogonal to the Y direction is parallel to the Z direction.

Each motor 18, 19, 21, 23 is a servo motor controlled and driven by an electronic control device 40.

The reciprocating movement W of the grinding wheel head 17 in the Y direction, that is, the rotational axis direction of the grinding wheel 30 and the reciprocating rotation ω of the main shaft 24 are
The grinding surface 31 of the sector gear G and the tooth surface TS of the tooth T of the sector gear G are synchronized with each other so that they are in meshing contact with each other.
9.23 in relation to each other. First, the electronic control device 40 operates the vertical feed motor 18 to advance the grindstone head 17 by a predetermined amount in the right direction in the X direction in FIG. The grinding wheel 30, which has been given an appropriate cut in the direction, moves to the leftmost side and the sector gear G rotates the most counterclockwise, indicating the left end position. In this position, the grinding surface 31 and the tooth surface TS are in meshing contact. They are not touching. From this left end position, grinding wheel 3
0 and the sector gear G synchronize with each other as described above and begin to move clockwise and rotate clockwise, the grinding surface 31 and the tooth surface TS start meshing contact, and the center position shown in FIG. 1(b) is reached. After passing through the position, the right end position shown in FIG. 1(C) is reached, and the meshing contact between the grinding surface 31 and the tooth surface TS is released. Thus, the grinding wheel 30, which is rotationally driven around the grinding wheel shaft 35, uses its grinding surface 31 to generate and grind the tooth surface TS of the sector gear G that meshes with the grinding wheel 30. In this embodiment, the movement of the grinding wheel head 17 in the X direction and the Y direction is such that, as shown in FIG. 3, the grinding wheel head 17 is moved upward in the X direction ( The electronic control unit 40 controls and drives both feed motors 18 and 19 in relation to each other so as to obtain such synchronization. do.

After the grinding wheel 30 and the sector gear G reach the right end position shown in FIG. The grinding surface 31 generates and grinds the tooth surface TS of the sector gear G that comes into contact with the grinding surface 31 as shown in FIG.
The left end position shown in al. Note that while this generating grinding is being performed, the lifting table 20 is moved by the lifting feed motor 21.
is being reciprocated at high speed in the Z direction. By carrying out the above operations, the tooth surface TS of the sector gear G is generated and ground over the entire length in the direction of the tooth trace.

Further, the rotation of the sector gear G does not necessarily have to be a reciprocating rotation, and the generation may be completed at the end of the rotation in the right direction.

As mentioned above, according to this embodiment, the rotation range of the sector gear G for the tooth surface TS is a range that somewhat exceeds the range in which the tooth surface TS and the ground surface 31 come into meshing contact with each other, as shown in FIG. The air grinding time is reduced compared to the conventional technique, and the grinding time is shortened by that amount.

In addition, in this embodiment, the grinding wheel head 17 is moved in the X direction and in the Y direction so that the whetstone head 17 is moved back by a predetermined minute amount to the left in the X direction in FIG. 2 at the center position of the Y direction movement.
Since the directional movements are synchronized with each other, the pitch circle diameter at the center of the ground sector gear G increases somewhat.

If a sector shaft S having such a sector gear G is used as a pitman shaft of a ball screw complete steering gear, the backlash value between the sector gear G and the rack that meshes with it will be such that the center part of the sector gear G meshes with the rack. Since it becomes negative near the neutral position of the steering wheel, the preload torque can be increased near the neutral position of the steering wheel. In this case, Y
By changing the relationship between the amount of movement in the Y direction and the amount of retraction in the X direction at the center position, it is also possible to arbitrarily change the change characteristics of the preload torque near the steering neutral position.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is an explanatory diagram of the operating state of the main parts, FIG. 2 is an overall side view of a sector gear grinding device embodying the present invention, and FIG. 3 is an illustration of an embodiment of the present invention. is the X on whetstone head 17
FIG. 4, which is a diagram showing the relationship between the movement in the direction and the Y direction, is an explanatory diagram of the prior art. Explanation of the symbols 30... Grinding wheel, 31... Grinding surface, 32... Annular projection, G... Sector gear, TS... Tooth surface.

Claims (1)

[Claims] In a sector gear grinding method in which the tooth surface of a sector gear is ground by a rotating grinding wheel, the sector gear is rotated about its axis, and the grinding wheel is provided with a plurality of annular protrusions along the circumferential direction on its outer periphery. A grinding surface having a rack-shaped cross section is formed by the surface, and the grinding surface is moved in the direction of the axis of rotation in synchronization with the rotation so that the grinding surface comes into meshing contact with the tooth surface of the sector gear, and the range of rotation and movement is The sector gear grinding method is characterized in that the sector gear is slightly larger than the entire range in which the tooth surface and the grinding surface mesh.