Cycloidal speed reducer for reducing stress of bushing

Abstract

The invention provides a cycloid speed reducer for reducing the stress of a bushing, which relates to the technical field and comprises an eccentric cam shaft, a first cycloid disc and a second cycloid disc, roller pins are arranged between the peripheral wall of the eccentric cam shaft and the inner walls of the first cycloid disc and the second cycloid disc; mounting holes are formed in the first cycloid disc and the second cycloid disc in the thickness direction in a penetrating mode, and bolts are screwed into the penetrating mounting holes from one side of the gland and connected to the flange base. The structure further comprises a wave-shaped bush, the portion, corresponding to the mounting hole, of the bolt is sleeved with the wave-shaped bush in a penetrating mode, the outer surface of the wave-shaped bush is in a periodical fluctuating outline, and the outer surface of the wave-shaped bush and the inner wall of the mounting hole form multi-point discrete contact so as to relieve the stress concentration phenomenon between the wave-shaped bush and the inner wall of the mounting hole. The invention has the beneficial effects that the multi-point discrete contact between the wave-shaped bushing and the inner wall of the mounting hole realizes the optimization and reconstruction of stress distribution, effectively inhibits the stress concentration phenomenon in the traditional continuous contact mode, and effectively prolongs the service life of the product.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission devices, and in particular to a cycloidal speed reducer for reducing bushing stress. Background Art

[0002] Industrial robots provide joint motion for joint structures with multiple degrees of freedom of joints through drive motors, servo motors, etc. In order to obtain high output torque from a servo motor or the like at the joint of the robot, a speed reducer is provided at the output end of the servo motor to increase the torque. Industrial robots adopt a harmonic drive method or a cycloidal drive method to decelerate the whole or a part of the robot. Among them, the cycloidal drive method is widely used in various industrial fields. In the cycloidal drive method, power is transmitted from the input shaft to the output shaft by a structure in which the external teeth of the cycloidal disk mesh with the internal teeth of the pinwheel housing and rotate, so that large torque transmission can be achieved, and a large reduction ratio can be formed, that is, the cycloidal speed reducer for reducing bushing stress mentioned at present.

[0003] The cycloidal speed reducer for reducing bushing stress is also called a cycloidal pinwheel speed reducer, which is a novel transmission device that applies the planetary transmission principle and adopts cycloidal pin tooth meshing. Due to its excellent transmission performance and high reduction ratio and other characteristics, it is widely used in drive or deceleration transmission operations in various industries. The cycloidal speed reducer is usually configured to use two or more cycloidal disks and form disks in opposite positions, and is configured so that the load does not deviate to one side.

[0004] The weakness (the position with the maximum stress) of the cycloidal speed reducer is mainly located in the contact area between the mounting hole of the cycloidal gear disk and the bushing. In theory, it is all line contact, but actually the currently used bushings are regular cylindrical shapes. As Figure 1 shown, the contact position between the bushing and the mounting hole is basically in area A, that is, stress concentration due to edge contact will occur. In addition, the other bushings in the circumferential direction also have uneven contact conditions, which will make the stress concentration condition more obvious and easily induce fatigue cracks. Therefore, it is necessary to disclose a cycloidal speed reducer for reducing bushing stress to overcome the above defects. Summary of the Invention

[0005] The present invention overcomes the disadvantages in the prior art and provides a cycloidal speed reducer for reducing bushing stress. A wavy bushing is provided at the mounting holes of the bolt and the first cycloidal disk and the second cycloidal disk, so that the two form multi-point discrete contact, so as to slow down the stress concentration phenomenon between the wavy bushing and the inner wall of the mounting hole and extend the service life.

[0006] In order to solve the above technical problems, the present invention is realized by the following technical solutions: A cycloidal speed reducer for reducing bushing stress, comprising: An eccentric camshaft is provided with a first cycloid disk and a second cycloid disk with a 180° phase difference at its two ends with different axes; needle rollers are arranged between the outer peripheral wall of the eccentric camshaft and the inner walls of the first cycloid disk and the second cycloid disk; It further includes a flange seat and a gland, and a needle hub is rotatably arranged outside the flange seat and the gland; The outer peripheries of the first cycloid disk and the second cycloid disk are provided with cycloid teeth, which form a one-tooth difference internal meshing reduction mechanism with the needle teeth annularly distributed on the inner wall of the needle hub; Installation holes are formed through the first cycloid disk and the second cycloid disk along the thickness direction, and bolts are screwed in from one side of the gland, penetrate through the installation holes and are connected to the flange seat; It further includes a corrugated bushing, and the corrugated bushing is sleeved on the bolt corresponding to the installation hole. The outer surface of the corrugated bushing has a periodic undulating profile, forming multi-point discrete contact with the inner wall of the installation hole to slow down the stress concentration phenomenon between the corrugated bushing and the inner wall of the installation hole.

[0007] Furthermore, the needle hub is rotationally matched with the flange seat and the gland through a thin crossed roller bearing.

[0008] Furthermore, deep groove bearings are arranged between the outer peripheral wall of the eccentric camshaft and the flange seat and the gland.

[0009] Furthermore, first oil seals are arranged between the eccentric camshaft and the gland and the flange seat.

[0010] Furthermore, second oil seals are arranged between the needle hub and the gland and the flange seat.

[0011] Compared with the prior art, the beneficial effects of the present invention are: The present invention provides a cycloid reduction device for reducing the stress of the bushing. A corrugated bushing is arranged at the installation holes of the bolts and the first cycloid disk and the second cycloid disk, so that the two form multi-point discrete contact to slow down the stress concentration phenomenon between the corrugated bushing and the inner wall of the installation hole, realizing the optimized reconstruction of the stress distribution, effectively suppressing the stress concentration phenomenon in the traditional continuous contact mode, and effectively prolonging the service life of the product. Description of the Drawings

[0012] The drawings are used to provide a further understanding of the present invention, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings: Figure 1 It is a schematic diagram of the contact position between a traditional cylindrical bushing and the installation hole of the cycloid disk; Figure 2 It is a three-dimensional view of the cycloid reduction device of the present invention; Figure 3 It is a sectional view of the cycloid reduction device of the present invention; Figure 4 is the exploded view of the cycloid speed reducer of the present invention; Figure 5 is the structural schematic diagram of the wavy bushing; Figure 6 is the schematic diagram of the contact position between the wavy bushing and the mounting hole of the cycloid disk.

[0013] In the figure: 1. Eccentric camshaft; 2. First cycloid disk; 201. Mounting hole; 3. Second cycloid disk; 4. Needle roller; 5. Flange seat; 6. Gland; 7. Needle hub; 8. Wavy bushing; 9. Bolt; 10. Thin crossed roller bearing; 11. Deep groove bearing; 12. First oil seal; 13. Second oil seal; A. Contact area between the traditional cylindrical bushing and the cycloid disk; B. Contact area between the wavy bushing and the cycloid disk. Specific embodiments

[0014] The following is a description of the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not used to limit the present invention.

[0015] As Figure 2 shown in Figure 6 the present invention claims a cycloid speed reducer for reducing the stress of the bushing, including: an eccentric camshaft 1, with a first cycloid disk 2 and a second cycloid disk 3 having a phase difference of 180° coaxially arranged at both ends. A needle roller 4 is arranged between the outer peripheral wall of the eccentric camshaft 1 and the inner walls of the first cycloid disk 2 and the second cycloid disk 3. The needle roller 4 forms a multi-point contact force transmission path with the cycloid wheel. Through the rolling contact of the needle roller 4, the high-speed rotational motion of the eccentric camshaft 1 is transmitted to the first cycloid disk 2 and the second cycloid disk 3 to rotate.

[0016] The outer peripheries of the first cycloid disk 2 and the second cycloid disk 3 are provided with cycloid teeth, which form a one-tooth difference internal meshing reduction mechanism with the needle teeth annularly distributed on the inner wall of the needle hub 7; the cycloid disk generates a compound motion under the action of the eccentric camshaft 1: both revolving around the axis of the eccentric camshaft 1 (eccentric motion) and rotating in the reverse direction around its own axis due to the tooth profile constraint; the continuous multi-point contact between the needle teeth and the cycloid teeth makes the load distribution more uniform, which helps to improve the transmission efficiency. The above is also the prior art of the cycloid speed reducer, which will not be elaborated here.

[0017] It further includes a flange seat 5 and a gland 6. Both the first cycloid disk 2 and the second cycloid disk 3 are located between the flange seat 5 and the gland 6. The needle hub 7 is rotatably arranged outside the flange seat 5 and the gland 6. Specifically, the needle hub 7 is rotationally matched with the flange seat 5 and the gland 6 through a thin crossed roller bearing 10.

[0018] Deep groove bearings 11 are provided between the outer peripheral wall of the eccentric camshaft 1 and both the flange seat 5 and the gland 6. In order to enhance the structural sealing performance, first oil seals 12 are provided between the eccentric camshaft 1 and both the gland 6 and the flange seat 5; second oil seals 13 are provided between the pin hub 7 and both the gland 6 and the flange seat 5. Through the arrangement of the first oil seals 12 and the second oil seals 13, it is possible to prevent the lubricating oil from leaking internally, isolating the components that need to be lubricated in the transmission components from the output components.

[0019] Mounting holes 201 are provided through the first cycloid disk 2 and the second cycloid disk 3 along the thickness direction. Bolts 9 are screwed in from one side of the gland 6, penetrate through the mounting holes 201 and are connected to the flange seat 5; thereby connecting the first cycloid disk 2 and the second cycloid disk 3 to the gland 6 and the flange seat 5 as a whole.

[0020] The main design point of this cycloid speed reducer is that it has a corrugated bushing 8. The corrugated bushing 8 is sleeved on the bolt 9 corresponding to the mounting hole 201, and Figure 5 It can be seen that the outer surface of the corrugated bushing 8 has a periodic undulating contour, so that it can form multi-point discrete contact with the inner wall of the mounting hole 201. As Figure 6 shown, the contact position between the corrugated bushing 8 and the mounting hole 201 of the cycloid disk is the B area, which is located in the middle position of the mounting hole 201, with multi-point contact, so as to slow down the stress concentration phenomenon between the corrugated bushing 8 and the inner wall of the mounting hole 201, realizing the optimized reconstruction of the stress distribution, effectively suppressing the stress concentration phenomenon in the traditional continuous contact mode, and effectively extending the service life of the product.

[0021] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A cycloid speed reducer for reducing bushing stress, characterized in that: include: An eccentric camshaft (1) having a first cycloid disc (2) and a second cycloid disc (3) disposed at two ends thereof with different axes and a phase difference of 180°; a needle roller (4) is disposed between the outer peripheral wall of the eccentric camshaft (1) and the inner walls of the first cycloid disc (2) and the second cycloid disc (3); It also includes a flange seat (5) and a gland (6), wherein a needle hub (7) is rotatably arranged outside the flange seat (5) and the gland (6); The outer circumferences of the first cycloid disc (2) and the second cycloid disc (3) are provided with cycloid teeth, which form a tooth difference internal meshing speed reduction mechanism with the needle teeth distributed in an annular pattern on the inner wall of the needle wheel hub (7); A mounting hole (201) is provided through the first cycloid disc (2) and the second cycloid disc (3) in the thickness direction, and a bolt (9) is screwed into the mounting hole (201) from one side of the gland (6) and connected to the flange seat (5); It also includes a wavy bushing (8), which is sleeved on the bolt (9) at a location corresponding to the mounting hole (201), and the outer surface of the wavy bushing (8) presents a periodic undulating profile, forming multiple points of discrete contact with the inner wall of the mounting hole (201), so as to alleviate stress concentration between the wavy bushing (8) and the inner wall of the mounting hole (201).

2. The cycloid speed reducer for reducing bushing stress according to claim 1, characterized in that: The needle wheel hub (7) is rotationally matched with the flange seat (5) and the pressure cover (6) via a thin cross roller bearing (10).

3. The cycloid speed reducer for reducing bushing stress according to claim 1, characterized in that: A deep groove bearing (11) is provided between the outer peripheral wall of the eccentric camshaft (1), the flange seat (5) and the gland (6).

4. The cycloid speed reducer for reducing bushing stress according to claim 1, characterized in that: A first oil seal (12) is provided between the eccentric camshaft (1), the pressure cover (6) and the flange seat (5).

5. The cycloid speed reducer for reducing bushing stress according to claim 4, characterized in that: A second oil seal (13) is provided between the needle wheel hub (7), the pressure cover (6) and the flange seat (5).

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