JPH0581781B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to rack and pinion mechanisms.

[Conventional technology]

As is well known, the rack and pinion mechanism consists of a rack having a large number of teeth formed at equal intervals on one surface, and a pinion having a large number of teeth formed on the outer periphery that mesh with the teeth of the rack.

This rack and pinion mechanism moves the rack in its length direction by rotating the pinion, or rotates the pinion by moving the rack in its length direction, and power transmission between the rack and pinion is carried out by the rack and pinion. This is done by the meshing of the teeth with the pinion.

By the way, the above-mentioned rack and pinion mechanism has the problem of generating backlash due to play in the meshing part between the rack and pinion. Therefore, it is necessary to control the rack feed amount or the rotation angle of the pinion with high precision. The drawback is that it cannot be done.

For this reason, it has been considered in the past to adjust the backlash of the rack and pinion mechanism.

FIG. 7 shows backlash removal means in a conventional rack and pinion mechanism, and here an example is shown in which the rack is moved by rotation of the pinion. This backlash removing means is constructed by meshing a rack 1 with a drive pinion 2 for moving the rack 1 and a backlash adjustment pinion 4 for removing backlash. are considered to be the same. The drive pinion 2 is fixed to a rotary shaft 3 and is rotated by the rotation of the rotary shaft 3, and the backlash adjustment pinion 4 is rotated by the rotation of the rotary shaft 3 through a friction clutch mechanism (not shown). The drive pinion 2 is fixed to a second rotating shaft 5 which is rotated in the opposite direction to the drive pinion 2. That is,
This backlash removing means is designed to absorb the play in the meshing part between the rack 1 and the drive pinion 2 by the backlash adjustment pinion 4, and the friction that causes the backlash adjustment pinion 4 to rotate in the opposite direction to the drive pinion 2. The clutch mechanism is
Because slipping occurs when a load greater than the friction transmission force is applied, the backlash adjustment pin 4
is rotated in the same direction as the drive pinion 2 by the movement of the rack 1 while pushing the rack 1 in the opposite direction to the direction in which the drive pinion 2 feeds the rack. Therefore, according to this backlash removing means, the teeth of the drive pinion 2 and the teeth of the rack 1 are always in contact with each other at their side surfaces, so that backlash can be prevented.

Note that here, the backlash adjustment pinion 4 is connected to a rotation shaft 5 that is different from the drive shaft 3 of the drive pinion 2.
However, the backlash adjustment pinion may be rotatably provided when the drive pinion is driven. In this case as well, if a mechanism is provided that rotates the backlash adjustment pinion in the opposite direction to the rotational direction of the drive pinion and causes it to slip against the backlash adjustment pinion when a load exceeding a predetermined value is applied, the backlash adjustment pinion can be adjusted. Since the pinion rotates in the same direction as the drive pinion due to movement of the rack while pushing the rack in the opposite direction to the rack feeding direction, backlash of the rack and pinion mechanism can be prevented.

[Problem to be solved by the invention]

However, if the backlash of the rack and pinion mechanism is removed by the backlash removing means as described above, the structure of the rack and pinion mechanism will become complicated, and the backlash adjustment pinion will always be in contact with the rack feed drive. Because of this resistance, the rotational driving force of the drive pinion must be higher than in a rack and pinion mechanism without backlash removal means.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a rack and pinion mechanism that can arbitrarily adjust the backlash without using a backlash adjustment pinion. It is in.

[Means to solve the problem]

In order to achieve the above object, the rack and pinion mechanism of the present invention has all the teeth of the rack tapered teeth whose tooth width becomes wider from one side of the rack toward the other side, and all of the teeth of the pinion teeth,
The rack has tapered teeth that become narrower from one side to the other.

[Effect]

That is, the rack and pinion mechanism of the present invention:
The amount of play in the meshing part between the rack and pinion can be adjusted by moving the pinion in its axial direction.The teeth of the rack and pinion are each tapered as described above, so the pinion can be adjusted easily. If it is moved in the axial direction, the distance between the opposing sides of the rack teeth and the pinion teeth changes accordingly, and the amount of play in the meshing part between the rack and pinion changes accordingly. Therefore, according to the rack and pinion mechanism of the present invention, the backlash can be adjusted arbitrarily without using a backlash adjustment pinion.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

First, the rack 10 will be explained. As shown in FIGS. 1 to 4, the rack 10 has a large number of teeth 11 formed at equal intervals on its upper surface. The teeth 11 of the rack 10 have a chevron-shaped cross section. I am doing it. All of the teeth 11 of this rack 10 are tapered teeth that become wider from one side of the rack 10 to the other side and have lead tapers at the same angle on both sides. Note that in the figure, the lead taper on the side surface of the tooth 11 is exaggerated for ease of understanding, but the lead taper angle θ on both sides of the tooth 11 is approximately 0°40'±0°10'. .

Further, as shown in FIGS. 1 to 4, the pinion 20 has a large number of teeth 21 formed on its outer periphery to mesh with the teeth of the rack 10, and both sides of the teeth 21 of the pinion 20 are involute. It has a curved cross section with a chevron shape. And this pinion 20
All of the teeth 21 of the rack 10 are tapered teeth with lead tapers at the same angle on both sides, which become narrower from one side of the rack 10 to the other.
The lead taper angle on both sides of Rack 10 is
This angle is approximately the same as the lead taper angle θ of the teeth 11. The teeth 11 of the rack 10 and the teeth 21 of the pinion 20 are both crouched on both sides, as shown in FIG.

This pinion 20 is attached to a drive shaft 22 which is orthogonal to the length direction of the rack 10.
It is attached so that it rotates together with 2.

Therefore, in the above rack and pinion mechanism, the teeth 11 and 21 of the rack 10 and the pinion 20 are
are tapered teeth whose tooth widths change in opposite directions, so by moving the pinion 20 in the axial direction while keeping the distance h between the axis O of the pinion 20 and the center of the rack constant, The amount of play in the meshing portion between 10 and pinion 20 can be adjusted as desired.

That is, in FIG. 5, the pinion 20 is
When moving in the direction of decreasing the overlap margin with (in the direction of arrow a in Figures 3 and 4),
This shows the state of meshing between the rack 10 and the pinion 20 at the center in the width direction of the rack 10. When the pinion 20 is moved in a direction to reduce the overlapping margin with the rack 10, as the pinion 20 moves in the axial direction, , tooth 11 of rack 10 and pinion 20
The distance between the opposing sides of the rack 10 and the pinion 21, that is, the play amount α of the meshing portion between the rack 10 and the pinion 20 increases, and the amount of backlash increases.

FIG. 6 also shows the relationship between the rack 10 and the pinion 20 at the widthwise center of the rack 10 when the pinion 20 is moved in the direction of increasing the overlapping margin with the rack 10 (in the direction of arrow b in FIGS. 3 and 4). It shows the state of engagement with the pinion 20.
When the rack 10 is moved in the direction of increasing the overlapping margin with the rack 10, contrary to the above, the distance between the opposing sides of the teeth 11 of the rack 10 and the teeth 21 of the pinion 20, that is, the meshing area between the rack 10 and the pinion 20 increases. The amount of play α becomes smaller, and as a result, the amount of backlash approaches zero.

Therefore, according to this rack and pinion mechanism, by moving the pinion 20 in a direction that increases the overlapping margin with the rack 10, the amount of backlash can be reduced to 0, and the amount of movement of the pinion 20 can be reduced to zero. By adjusting , the amount of backlash can be adjusted as desired. In addition,
The amount of adjustment of the backlash relative to the amount of movement of the pinion 20 is determined by the ratio of the rack 10 and the teeth 11 of the pinion 20.
When the lead taper angle θ on both sides of 20 is 0°40', it is 0.024 mm for 1 mm of pinion movement. In addition, the teeth 11 of the rack 10 and the pinion 20,
When the teeth 11 and 21 are worn, the backlash amount changes accordingly.In this case, too, if the pinion 20 is moved in the direction of increasing the overlapping margin with the rack 10, the backlash amount changes due to the wear of the teeth 11 and 21. can be compensated.

In this way, the rack and pinion mechanism of the above embodiment can adjust the backlash as desired without using the backlash adjustment pinion 4 shown in FIG. In addition, according to this rack and pinion mechanism, it is possible to reduce the amount of backlash to almost 0, so it is possible to achieve rack feed with the same high precision as a ball screw. It can be used as an extremely inexpensive alternative to the feeding mechanism. In addition, the rack and pinion mechanism described above can feed the rack 10 at a high speed of 30 m/sec to 50 m/sec, and the ball screw (maximum feeding speed 20 m/sec)
The racks 10 can be joined together to form a long-distance feeding mechanism.

The axial movement of the pinion 20 may be performed by moving the rotating shaft 22 in the axial direction, or the pinion 20 may be mounted so as to be movable in the axial direction with respect to the rotating shaft 22. , only the pinion 20 may be moved. Also,
Even if the teeth 11 and 21 of the rack 10 and the pinion 20 are "spur teeth" whose length direction is parallel to the width direction of the rack 10 and the axial direction of the pinion 20, the teeth 11 and 21 of the rack 10 and the pinion 20 are It may also be a "helical tooth" diagonal to the direction.

〔Effect of the invention〕

In the rack and pinion mechanism of the present invention, all the teeth of the rack are tapered teeth whose width increases from one side of the rack to the other side, and all the teeth of the pinion are tapered from one side of the rack to the other side. Since the teeth are tapered to become narrower toward the other side, the buckle can be adjusted as desired without using a buckle rush adjustment pinion.

[Brief explanation of drawings]

1 to 6 show an embodiment of the present invention. FIGS. 1 and 2 are a plan view and a front view of the rack and pinion mechanism, and FIG.
4 is an enlarged plan view of the teeth of the rack and pinion, and FIGS. 5 and 6 respectively show changes in the meshing state of the rack and pinion when the pinion is moved in the axial direction. FIG. 3 is an enlarged cross-sectional view along the length of the rack. FIG. 7 is a plan view showing backlash removal means in a conventional rack and pinion mechanism. 10...Rack, 11...Teeth, 20...Pinion, 21...Teeth, 22...Rotating shaft.

Claims (1)

[Claims] 1 Consisting of a rack and a pinion, all the teeth of the rack are tapered teeth whose width becomes wider from one side of the rack to the other side, and all the teeth of the pinion are tapered teeth that widen from one side of the rack to the other side. A rack and pinion mechanism characterized by tapered teeth that become narrower from one side to the other.