JPH09324837A - Worm gear reducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a worm gear reducer in which a transmitting efficiency between a worm and a wheel is remarkably superior, a gear reduction ratio can be expanded and no back-lash is generated. SOLUTION: A helical worm groove 6a is formed around a column-like worm 6 arranged at an input shaft 2. A plurality of roller pins 8 are equally spaced apart in a ring-shape and arranged at a disc plane of a wheel 7 installed at an output shaft 3 crossed at a right angle with the input shaft 2. Each of the roller pins 8 is rotatably supported at the wheel 7 through a needle bearing 9 and a thrust bearing 10 and concurrently pushed against the worm groove 6a by a biasing means 12. The extremity end of the roller pin 8 is formed with a tapered section and abutted against only one side surface of the worm groove 6a. In addition, the plurality of roller pins 8 are concurrently engaged with the worm groove 6a, wherein an abutting direction between each of the roller pins 8 and the worm groove 6a is set such that they are oppositely abutted against an axial center of the worm 6 in right and left reversed states.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a worm speed reducer in which a worm and a wheel mesh with each other to transmit rotational power.

[0002]

2. Description of the Related Art A general conventional worm speed reducer is composed of a worm having a spiral tooth trace and a wheel meshing with the worm. The number of teeth of the wheel is set to be larger than the number of teeth of the worm. It is a thing. Therefore, when the worm is rotationally driven, the wheel is decelerated and rotated.

[0003]

Since the conventional worm speed reducer has a structure in which power is transmitted by sliding contact between tooth surfaces, friction due to sliding contact between tooth surfaces is large and power transmission efficiency is high. Had a very low defect of 60% or less. Further, in the conventional worm speed reducer, it is difficult to reduce the speed reduction ratio to 1:10 or less because the sliding friction of the tooth surface is large. For example, the speed reduction ratio is the most required when the size and speed of the conveyor is increased. It could not correspond to 1: 5 to 1:10. Further, in the conventional worm speed reducer, a clearance due to meshing is an essential condition, and it is difficult to remove the backlash.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention that transmission efficiency between a worm and a wheel is very excellent, a reduction ratio range can be widened, and backlash can be eliminated. The purpose is to provide a worm reducer that can

[0005]

The worm speed reducer of the present invention employs the following technical means. [Means of Claim 1] In a worm speed reducer, a worm having a groove-shaped worm groove provided around the worm and a plurality of meshing means for meshing with the worm groove are provided on a disc surface axially and facing the worm. And a wheel that is mounted.

The meshing means is a roller pin which is rotatably supported by the wheel through a rotary bearing and is also rotatably supported by the wheel through a thrust bearing. Further, the roller pin is pressed toward the worm groove by the urging means, and the tip of the roller pin that abuts the worm groove is provided in a tapered shape to be pressed against the tapered side surface of the worm groove. Further, the plurality of roller pins simultaneously engage with the worm groove.

[Means for Claim 2] In the worm speed reducer according to claim 1, the worm groove is formed by a combined trajectory of two motions of a uniform speed circular motion of the roller pin and a uniform speed rotary motion of the worm. The taper portion at the tip of the roller pin contacts only one side surface of the worm groove, and the abutting direction of the plurality of roller pins and the worm groove in the axial direction of the wheel is one of the worm grooves. It is characterized in that it is provided so that the side and the other side are reversed.

[0008]

[Operation and effect of the invention]

When the worm is driven to rotate, the worm groove formed around the worm rotates. Along with the rotational movement of the worm groove, the roller pin that meshes with the worm groove rotates, moves in a circular shape, and the wheel rotates.

[Effect of Claim 1] Since the roller pin is rotatably supported by the wheel via a rotary bearing and is rotatably supported by the wheel via a thrust bearing, the roller pin is urged. The roller pin can be easily rotated with respect to the worm even when it is pressed against the worm groove by the means.

As described above, since the roller pin can be easily rotated, the resistance between the worm and the wheel is very small, and the power transmission efficiency between the worm and the wheel is higher than in the conventional case. Further, since the resistance is small, heat generation due to wear and friction is small, and therefore it can be used for high-speed input.

Further, since the resistance between the worm and the wheel is very small, it is possible to obtain a reduction ratio in a wider range as compared with the conventional one. Further, since the plurality of roller pins mesh with the worm groove, the torque transmission force is high. Further, since the plurality of roller pins mesh with the worm groove, errors in each meshing portion are averaged, so that the rotation transmission accuracy is high.

[Operation and Effect of Claim 2] A plurality of roller pins mesh with the worm groove. Here, if the tapered part of each roller pin contacts both sides of the worm groove,
The roller pin becomes difficult to rotate. However, according to the second aspect, since each roller pin contacts only one side surface of the worm groove, the roller pin can rotate more easily than when it contacts both sides of the worm groove.

In this way, the tapered portion of the roller pin is
If it is provided so as to contact only one side of the worm groove,
A gap is generated on the other side surface side of the worm groove, which causes rattling. However, according to the second aspect, the roller pins meshing with the worm groove are provided such that the contact direction with the worm groove is opposite between the one side and the other side of the worm.

As a result, there is no rattling between the worm and the wheel through the plurality of roller pins, and backlash can be eliminated. Therefore, even if the input rotation is reversed, a smooth rotation output can be obtained without rattling at the time of reverse rotation.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a worm speed reducer of the present invention will be described based on an embodiment shown in the drawings. [Structure of Embodiment] FIGS. 1 to 8 are for explaining an embodiment, FIGS. 1 and 2 are sectional views of a worm speed reducer, and FIG. 3 is a description for explaining engagement between a plurality of roller pins and a worm. 4 and 5 are cross-sectional views of the essential parts of the worm speed reducer showing the rotation support state of the roller pin.

The worm speed reducer 1 of the present embodiment includes a carrier device, joints of industrial robots, machine tools, precision machines, etc.
It is used in a mechanical device that requires high efficiency, high accuracy, long life, and high torque transmission, and decelerates the rotational power transmitted to the input shaft 2 and transmits it to the output shaft 3. In addition,
The input shaft 2 and the output shaft 3 intersect vertically without intersecting each other, and each of them is connected to the case 5 via the bearing 4.
It is rotatably supported by.

The deceleration of the rotational power is performed by meshing between the worm 6 fixed to the input shaft 2 and the wheel 7 fixed to the output shaft 3, and is provided around the worm 6 in a spiral shape. The worm groove 6 a meshes with a roller pin 8 which is a meshing means annularly arranged on the disk surface in the axial direction of the wheel 7, and transmits the power of the worm 6 to the wheel 7.

The worm 6 of this embodiment has a worm groove 6a provided in a spiral shape around a cylindrical body. The worm groove 6a is provided so that the plurality of roller pins 8 arranged between the worm 6 and the wheel 7 mesh with the worm groove 6a at the same time (see FIG. 3).

Now, the roller pin 8 will be described with reference to FIG. The roller pins 8 are arranged in a plurality of wheels at equal intervals on the disk surface in the axial direction of the wheel 7, and have needle bearings 9 press-fitted between the roller pin 8 and the wheel 7.
It is rotatably supported by the wheel 7 via a (rotary bearing). In addition, the rear portion of the roller pin 8 (anti-worm 6
Side), thrust bearing 1 using multiple balls
0 (thrust bearing) is arranged, and even if the roller pin 8 receives a thrust force (a force by which the roller pin 8 is pressed against the worm groove 6a, which will be described later), the roller pin 8 is rotatably supported by the wheel 7.

Biasing means 12 are provided between the rear portion of each thrust bearing 10 and the rear lid 11, and are provided so as to press each roller pin 8 individually into the worm groove 6a of the worm 6. There is. On the other hand, the tip of the roller pin 8 (the shape of the portion pressed against the worm groove 6a) is formed with a tapered taper 8a that matches the tapered side surface of the worm groove 6a.

Here, the taper 8a of the roller pin 8 is
It contacts only one side surface of the worm groove 6a,
The contact direction between each roller pin 8 and the worm groove 6a is provided so as to be opposite on one side and the other side of the axial center of the worm 6. Specifically, in this embodiment, FIG.
As shown in FIG. 6 and FIG. 6, the contact direction between each roller pin 8 and the worm groove 6 a is provided so as to contact the outside with respect to the axial center of the worm 6. In addition, in this embodiment, the worm 6 is provided so as to hit the outside with respect to the axial center, but it may be provided so as to hit the inside with respect to the axial center of the worm 6.

A processing technique for forming the worm groove 6a in the worm 6 will be described. The unrolled worm 6 without the worm groove 6a is driven to rotate, and a cutting milling cutter equipped with an end mill for cutting the worm groove 6a is provided with a roller pin 8
A constant speed circular motion is performed along the pitch circle drawn by. Then
The worm groove 6a formed by the combined trajectory of the two motions of the constant velocity circular motion of the roller pin 8 and the constant velocity rotary motion of the worm 6,
It is formed around the worm 6.

A technique for making the contact direction between the taper 8a of the roller pin 8 and the worm groove 6a on one side and the other side of the axial center of the worm 6 will be described. As shown in FIG. 5 and FIG. 6, the worm groove 6a is used for external contact.
At the time of forming, the groove pitch of the central portion is subtracted from the designed basic pitch P by a predetermined pitch α, and the other groove pitch is the basic pitch P to form the worm groove 6a (see FIG. 7). On the contrary, in order to make the inner contact, when forming the worm groove 6a, the groove pitch at the center is set to the designed basic pitch P.
On the other hand, the worm groove 6a is formed by adding a predetermined pitch α, and the other groove pitch is the basic pitch P (see FIG. 8).

The rotation speed of the unprocessed worm 6
The speed of the circular motion of the cutting milling cutter is set by the reduction ratio of the worm reducer 1. In addition, the above cutting technology is
It can be easily implemented by using a C milling cutter.

[Operation of Embodiment] Next, the operation of the above embodiment will be briefly described. Input shaft 2 depending on the output of the motor
When is driven to rotate, the worm 6 rotates together with the input shaft 2. The spiral worm groove 6a is rotated by the rotation of the worm 6, and a circular motion is given to the roller pin 8 meshing with the worm groove 6a. Then, the roller pin 8 itself rotates by the rotation of the worm groove 6a, and the roller pin 8 makes a circular motion. The circular movement of the roller pin 8 causes the wheel 7 to move.
Rotates, and the output shaft 3 rotates. As a result, the rotational power transmitted to the input shaft 2 is decelerated and transmitted to the output shaft 3.

[Effects of the Embodiment] Since the roller pin 8 is rotatably supported by the wheel 7 via a rotary bearing and is also rotatably supported by the wheel 7 by a thrust bearing 10, the roller pin 8 is rotatably supported. Even if 8 is pressed toward the worm groove 6 a by the biasing means, the roller pin 8 can easily rotate with respect to the worm 6. Therefore, the resistance between the worm 6 and the wheel 7 is very small, and the power transmission efficiency between the worm 6 and the wheel 7 is higher than in the conventional case. Further, since the resistance is small, heat generation due to wear and friction is small, and therefore it can be used for high-speed input.

Further, since the resistance between the worm 6 and the wheel 7 is very small, it is possible to obtain a reduction ratio in a wider range as compared with the conventional one. Specifically, in the past, since the sliding friction of the tooth surface was large, it was difficult to reduce the reduction ratio to 1:10 or less. However, the present invention can reduce the reduction ratio to 1: 1.

The speed reduction ratio is determined by the number of rollers and the number of threads of the worm groove 6a. For example, when the number of rollers is 10, when the speed reduction ratio is 1:10, the number of threads =
1, when the reduction ratio is 1: 5, the number of threads is 2, and the reduction ratio is 1: 2.
When the number is 5, the number of grooves in the groove is 4, and when the reduction ratio is 1: 2, the number of threads is 5
It is.

Furthermore, since a plurality of roller pins 8 are simultaneously engaged with the worm groove 6a, the torque transmission force is high. Further, since the plurality of roller pins 8 mesh with the worm groove 6a at the same time, the error of each meshing portion is averaged, so that the rotation transmission accuracy is high.

Next, the effect of providing the roller pins 8 and the worm groove 6a in the abutting direction against the axial center of the worm 6 in the opposite direction will be described. When the taper 8a of the roller pin 8 contacts both side surfaces of the worm groove 6a, it becomes difficult for the roller pin 8 to rotate. However, as shown in this embodiment, the taper 8a of each roller pin 8 has the worm groove 6a.
Since it contacts only one side of the roller groove 8, the roller pin 8 can be rotated more easily than when it contacts both sides of the worm groove 6a.

Further, the taper 8a of each roller pin 8 is
When it is provided so as to contact only the side surface in one direction, a gap is generated on the other side surface side of the worm groove 6a and rattling occurs. However, as shown in this embodiment, each roller pin 8 has one of the worm grooves 6a. It touches either side or the other side. For this reason, there is no rattling between the worm 6 and the wheel 7 through the plurality of roller pins 8, and backlash can be eliminated. Further, even if the input rotation is reversed, a smooth rotation output can be obtained without rattling at the time of reverse rotation.

On the other hand, in the conventional worm speed reducer, there is a method of providing the worm 6 in an hourglass shape in order to increase the tooth engagement ratio, but it has a drawback that it is difficult to manufacture and assemble. On the other hand, the worm 6 according to the present embodiment achieves a high meshing rate even though it has a cylindrical shape.

[Brief description of drawings]

FIG. 1 is a cross-sectional perspective view of a worm speed reducer.

FIG. 2 is a sectional view of a worm reducer.

FIG. 3 is an explanatory diagram illustrating meshing between a plurality of roller pins and a worm.

FIG. 4 is a cross-sectional view of a main part of a worm speed reducer showing a rotation support state of roller pins.

FIG. 5 is an explanatory diagram illustrating a contact direction between a plurality of roller pins and a worm groove.

FIG. 6 is a cross-sectional view illustrating a contact direction between a plurality of roller pins and a worm groove.

FIG. 7 is an explanatory diagram of a groove pitch for external contact.

FIG. 8 is an explanatory diagram of a groove pitch for inner contact.

[Explanation of symbols]

 1 Worm reducer 6 Worm 6a Worm groove 7 Wheel 8 Roller pin (meshing means) 8a Taper 9 Needle bearing (rotary bearing) 10 Thrust bearing (thrust bearing) 12 Energizing means

Claims (2)

[Claims] 1. A worm having a groove-like worm groove provided around the worm, and a plurality of meshing means for meshing with the worm groove,
And a wheel provided on a disk surface facing the worm in the axial direction, wherein the meshing means is rotatably supported by the wheel via a rotary bearing and is also supported by the wheel via a thrust bearing. A roller pin rotatably supported in thrust, the roller pin being pressed toward the worm groove by an urging means, and the tip of the roller pin abutting the worm groove is provided on a tapered side surface of the worm groove. A worm speed reducer, which is provided in a tapered shape to be pressed, and wherein a plurality of the roller pins are simultaneously engaged with the worm groove. 2. The worm reducer according to claim 1, wherein the worm groove is formed by a combined locus of two motions of a constant speed circular motion of the roller pin and a constant speed rotary motion of the worm. The tapered portion at the tip is in contact with only one side surface of the worm groove, and the abutting directions of the plurality of roller pins and the worm groove in the axial direction of the wheel are one side and the other side of the worm. A worm reducer characterized by being installed in reverse.