JPH07127694A - Non-backlash gear transmission - Google Patents

Abstract

PURPOSE:To provide a non-backlash gear transmission mechanism having a minimum number of gears, in which one of meshed gears is machined so as to be dislocated with a large tooth thickness, and is then incorporated in order to eliminate backlash. CONSTITUTION:Meshed gears 5, 6, 7, 8 in two pairs are journalled in a bisplit casing 1 which divides a transmission along the center-axial plane, and one of each pair of these gears is machined so as to be dislocated in order to decrease backlash to substantially zero, and is then incorporated. Further, at least one pair of these gears are helical gears which are mounted by axially fixing bearings 9 for an input shaft 2, an intermediate shaft 3, and an output shaft 4 with the use of thrust washers 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a no-backlash gear reducer driven by a servomotor or the like.

[0002]

2. Description of the Related Art When a servo motor drives an operating arm of a robot through a gear reducer,
Backlash in the gear reducer makes it impossible to stop the working arm in place. Therefore, in such a case, a backlash gear reducer is used.

Various types of no-backlash gear reducers have been proposed so far. For example, the one in which the backlash is moved to one side and the forward and backward movements are driven by using the meshing of the surfaces without backlash, or one of the pair of gears has the tooth surface sandwiched by the other two gears. Some of them are attached for use.

[0004]

The conventional no-backlash gear reducer requires a large number of gears, which is inconvenient and expensive to manufacture.

In view of the above point, the present invention uses a minimum number of gears so that one of the meshing gears is free from backlash.
The object of the present invention is to obtain a no-backlash gear reducer with a low manufacturing cost by making a tooth thickness thickly displace and cutting it, and incorporating it.

[0006]

In order to achieve the above object, the no-backlash gear reducer of the present invention is mounted in a split case in which a reducer having two pairs of meshing gears is divided by a shaft core surface. , One of the two pairs of meshing gears is dislocated so that the backlash is close to 0, cut and formed, and this is incorporated. Further, one or two pairs of the two pairs of meshing gears are helical gears, and the ball bearings of the input shaft, the intermediate shaft, and the output shaft are axially fixed and attached by thrust washers.

[0007]

Since the case is divided into two parts at the shaft center surface, two pairs of meshing gears can be housed in one case, and the intermediate shaft can be fixed and the input shaft to the intermediate shaft can be fixed. It is convenient for measuring the amount of backlash on the output shaft. Any one of the two pairs of meshing gears is cut and formed by shifting the tooth thickness so that the backlash amount becomes close to 0, and by incorporating this, it becomes a no backlash gear reducer. The number of gears used can be minimized. Further, when the helical gear is used, when the input shaft, the intermediate shaft, and the output shaft move in the axial direction, it is the same as the backlash even if there is no backlash between the tooth flanks of the gear. In order to prevent this, the thrust washer that stops the ball bearings of the input shaft, the intermediate shaft, and the output shaft in the axial direction is fixed in the groove provided in the case without any gap, so that the thrust washer can be fixed in the axial direction to eliminate backlash. In this case as well, since the case is divided into two parts by the axial center surface, the thrust washers having different thicknesses can be easily replaced.

[0008]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2 are explanatory views of a first embodiment of a no-backlash gear reducer of the present invention. FIG. 1 is a plan view showing a state in which an upper portion of a split case is removed, and FIG. FIG. 3 is a side view seen along the direction, and FIG. 3 is an explanatory view of a second embodiment of the present invention. As shown in FIGS. 1 and 2, the no-backlash gear reducer of the first embodiment has a case 1. The case 1 is cast using a metal such as a light alloy, and has an input shaft 2, an intermediate shaft 3, and an output shaft 4.
It is designed so that it can be divided into two parts at the shaft center surface of. Also,
The case 1 that has been divided is stacked vertically and bolts (not shown)
They can be fastened together and integrated as shown in FIG. Further, a pair of meshing gears 5 and 6 is provided between the input shaft 2 and the intermediate shaft 3, and a pair of meshing gears 7 and 8 is provided between the intermediate shaft 3 and the output shaft 4. . Both sides of the input shaft 2, the intermediate shaft 3, and the output shaft 4 are rotatably mounted on the case 1 by a ball bearing 9 or a roller bearing 10.

In the embodiment, a pair of meshing gears 5, 6 are provided, respectively.
And 7 and 8 are configured as follows to form a no-backlash gear reducer. Initially, the meshing gears 5, 6, 7, 8
Assemble the one cut to the standard. Then, the intermediate shaft 3 is fixed so as not to move, and the input shaft 2 and the output shaft 4 are reciprocally rotated to measure the amount of backlash between the meshing gears 5 and 6 and the meshing gears 7 and 8. To this end, a lever arm is fixed to the input shaft 2 and the output shaft 4, the turning length of the tip is measured with a dial gauge, the rotation angle of the input shaft 2 and the output shaft 4 is obtained, and this is determined by the meshing gears 5. Convert to backlash of 6-mesh gears 7 and 8. As a result, the actual center distances of the gears 5, 6 and 7, 8 that have been standardly cut can be obtained, including the influence of the radial clearance including the ball bearing 9 and the like. Next, a dislocation coefficient that can set the backlash amount to 0 or a value close to 0 at the obtained actual center distance is obtained. In this case, only one of the pair of meshing gears 5, 6 and 7, 8 needs to be dislocated, and the standardly cut gear is replaced with the gear formed by cutting according to the dislocation coefficient. This creates a non-backlash reduction gear.

Next, a second embodiment will be described. The meshing gears 5, 6 and 7, 8 may be meshed with a helical gear. In this case, when the helical gears of the input shaft 2, the intermediate shaft 3, and the output shaft 4 move in the axial direction,
The thrust washer 11 that stops the thrust of the ball bearing 9 is selected so that it does not move in the axial direction, because it is the same as when it has backlash. in this case,
The thrust washer 11 is selected to have a thickness that fits tightly in the thrust receiving groove 12 of the case 1. When the shaft is supported by the two ball bearings 9 arranged side by side, it is sufficient to fix one ball bearing 9 in the axial direction. Needless to say, the gear used in the present invention is not limited to such a helical gear, and various types of gears can constitute the no-backlash gear reducer of the present invention.

[0011]

As described above, since the present invention is configured as described above, one of the pair of meshing gears is formed by cutting the tooth thickness so that the tooth thickness is changed so as to eliminate backlash. By incorporating it, a backlash gear reducer with a minimum number of gears can be obtained. As a result, the manufacturing cost can be significantly reduced and the size can be reduced.
Further, the helical gear can be used by preventing the ball bearing of the shaft to which the gear is attached from moving in the axial direction.

[Brief description of drawings]

FIG. 1 is a vertical plan view showing a no-backlash gear reducer according to a first embodiment of the present invention with an upper case removed.

FIG. 2 is a side view of the gear reducer of FIG. 1 viewed from an axial direction.

FIG. 3 is an enlarged vertical sectional view showing a second embodiment of the present invention when a helical gear is used between an input shaft and an intermediate shaft.

[Explanation of symbols]

 1 case 2 input shaft 3 intermediate shaft 4 output shaft 5, 6, 7, 8 meshing gear 9 ball bearing 11 thrust washer

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[Procedure amendment]

[Submission date] May 19, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

Since the case is divided into two parts at the shaft center surface, two pairs of meshing gears can be housed in one case, and the intermediate shaft can be fixed and the input shaft to the intermediate shaft can be fixed. It is convenient for measuring the amount of backlash on the output shaft. Any one of the two pairs of meshing gears is cut and formed by shifting the tooth thickness so that the backlash amount becomes close to 0, and by incorporating this, it becomes a no backlash gear reducer. The number of gears used can be minimized. Further, when the helical gear is used, when the input shaft, the intermediate shaft, and the output shaft move in the axial direction, it is the same as the backlash even if there is no backlash between the tooth flanks of the gear. To prevent this, thrust washer that stops the ball bearings of the input shaft, intermediate shaft, and output shaft in the axial direction.
Alternatively, attach the circlip to the case and input shaft, intermediate shaft,
It can be fixed in the axial direction by stopping it in the groove provided on the force shaft without any gap, and it can be made free from backlash. In this case as well, since the case is divided into two parts by the axial center surface, the thrust washers having different thicknesses can be easily replaced.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Next, a second embodiment will be described. The meshing gears 5, 6 and 7, 8 may be meshed with a helical gear. In this case, when the helical gears of the input shaft 2, the intermediate shaft 3, and the output shaft 4 move in the axial direction,
The thrust washer 11 that stops the thrust of the ball bearing 9 is selected so that it does not move in the axial direction, because it is the same as when it has backlash. in this case,
The thrust washer 11 is selected to have a thickness that fits in the groove 12 of the thrust receiver of the case 1, the input shaft 2, the intermediate shaft 3, and the output shaft 4 without any gap. When the shaft is supported by the two ball bearings 9 arranged side by side, it is sufficient to fix one ball bearing 9 in the axial direction. Needless to say, the gear used in the present invention is not limited to such a helical gear, and various types of gears can constitute the no-backlash gear reducer of the present invention.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

As described above, since the present invention is configured as described above, one of the pair of meshing gears is formed by cutting the tooth thickness so that the tooth thickness is changed so as to eliminate backlash. By incorporating it, a backlash gear reducer with a minimum number of gears can be obtained. As a result, the manufacturing cost can be significantly reduced and the size can be reduced.
Further, the helical gear can be used by preventing the ball bearing of the shaft to which the gear is attached from moving in the axial direction. If the reduction ratio may be small,
The intermediate shaft may be used as the output shaft by using only the gear.

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (2)

[Claims] 1. A speed reducer having two pairs of meshing gears is mounted in a split case that is divided by a shaft surface so that any one of the two pairs of meshing gears has a backlash close to zero. A non-backlash gear reducer characterized in that it is formed by transposing and cutting, and is incorporated. 2. A pair of or two pairs of meshing gears are helical gears, and ball bearings of an input shaft, an intermediate shaft, and an output shaft are axially fixed by thrust washers. The no-backlash gear reducer according to claim 1.