JP2018199203A - Robot and gear device - Google Patents

Abstract

To provide a robot capable of prolonging a service life of a gear device, and the gear device.SOLUTION: A gear device includes: an internal gear; a flexible external gear partially meshing with the internal gear; a wave generator being brought into contact with an inner peripheral surface of the external gear and moving a meshing position of the internal gear and the external gear in a circumferential direction; and lubricant disposed at a lubrication object part being at least one part between the internal gear and the external gear and between the external gear and the wave generator. The lubricant contains base oil, a thickening agent, and an organic molybdenum compound, and has an oil separation degree falling within a range of 4 mass% or more and of 13.8 mass% or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a robot and a gear device.

  In a robot including a robot arm configured to include at least one arm, for example, a joint portion of the robot arm is driven by a motor. In general, rotation of the driving force from the motor is reduced by a reduction gear (gear device). To be done.

  As such a speed reducer, for example, a speed reducer described in Patent Document 1 is known. The speed reducer described in Patent Document 1 includes a circular spline, a flex spline, and a wave generator. In this speed reducer, when the circular spline is fixed and the wave generator is turned, the flexspline is elastically deformed, and the meshing position with the circular spline moves sequentially. Here, when the wave generator makes one revolution, the flexspline has two fewer teeth than the circular spline, and accordingly moves in the direction opposite to the rotation direction of the wave generator. In general, the movement is taken out as an output.

  Moreover, the speed reducer described in Patent Document 1 uses a grease containing a base oil in which an aliphatic hydrocarbon oil and polymethacrylate are used together, and a thickener for lubrication between the wave generator and the flexspline. Patent Document 1 discloses that a solid lubricant such as molybdenum disulfide and graphite is added to the grease.

JP-A-3-179904

  However, the speed reducer described in Patent Document 1 has insufficient lubrication performance of grease, and has a problem that, for example, when used in a robot, the flexible gear is easily damaged.

  Here, as one of means for improving the lubricating performance of the lubricant, an organic molybdenum compound can be added to the lubricant. However, since the particle diameter of the organic molybdenum compound is generally as large as about 10 μm, simply using the organic molybdenum compound inhibits the organic molybdenum compound from exuding the base oil from the thickener, thereby improving the lubricating performance of the lubricant. It is difficult to raise enough.

  An object of the present invention is to provide a robot and a gear device that can extend the life of the gear device.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following application examples or forms.

The robot of this application example includes a first member,
A second member rotatably provided with respect to the first member;
A gear device that transmits a driving force from one side to the other side of the first member and the second member,
The gear device is
An internal gear,
A flexible external gear partially meshed with the internal gear;
A wave generator that contacts an inner peripheral surface of the external gear and moves a meshing position of the internal gear and the external gear in a circumferential direction;
A lubricant disposed between at least one of the internal gear and the external gear and between the external gear and the wave generator;
One of the internal gear, the external gear and the wave generator is connected to the first member, and the other is connected to the second member.
The lubricant includes a base oil, a thickener, and an organic molybdenum compound, and has a degree of oil separation within a range of 4% by mass to 13.8% by mass.

  According to such a robot, it is arranged between at least one of the internal gear and the external gear that are the lubrication target part, and between the external gear and the wave generator that is the lubrication target part. Since the lubricant contained contains the organic molybdenum compound, it is possible to effectively reduce the friction in the lubrication target portion (particularly, the meshing portion between the internal gear and the external gear). In addition, since the oil separation degree of the lubricant is in the range of 4% by mass or more and 13.8% by mass or less, the base oil from the thickener is contained even if the lubricant contains an organic molybdenum compound. It is difficult for the seepage to be inhibited, and the base oil can be stably supplied to the lubrication target portion (particularly, the contact portion between the external gear and the wave generator). Thus, the lubricant can stably supply the base oil to the lubrication target part by the exudation of the base oil from the thickener, while exhibiting the excellent friction reducing effect by the organic molybdenum compound. As a result, the life of the gear device can be extended.

  In the robot according to this application example, it is preferable that the consistency of the lubricant is in a range of 325 to 365.

  As a result, the lubricant can be easily retained on the lubrication target portion. In addition, there is an advantage that the oil separation degree of the lubricant can be easily set within the above-described range.

  In the robot of this application example, it is preferable that the dropping point of the lubricant is in a range of 248 ° C. or higher and 270 ° C. or lower.

  Thereby, the heat resistance of the lubricant can be made excellent while optimizing the consistency of the lubricant.

  In the robot according to this application example, it is preferable that the thickener includes a lithium composite soap.

  Thereby, the dropping point of the lubricant can be increased, and the heat resistance of the lubricant can be improved.

  In the robot of this application example, it is preferable that the internal gear is made of chromium molybdenum steel.

  Thereby, the internal gear can obtain good fatigue strength, and a gear device with a long life can be realized.

  In the robot of this application example, it is preferable that the external gear is made of nickel chrome molybdenum steel.

  As a result, the wear of the teeth of the flexible gear can be reduced, and a gear device with a longer life can be realized.

The gear device of this application example includes an internal gear,
A flexible external gear partially meshed with the internal gear;
A wave generator that contacts an inner peripheral surface of the external gear and moves a meshing position of the internal gear and the external gear in a circumferential direction;
A lubricant disposed between at least one of the internal gear and the external gear and between the external gear and the wave generator;
The lubricant includes a base oil, a thickener, and an organic molybdenum compound, and has a degree of oil separation within a range of 4% by mass to 13.8% by mass.

  According to such a gear device, it is disposed at least one of the internal gear and the external gear that are the lubrication target portion and between the external gear and the wave generator that is the lubrication target portion. Since the lubricant which contains the organomolybdenum compound, it is possible to effectively reduce the friction in the lubrication target portion (particularly the meshing portion between the internal gear and the external gear). In addition, since the oil separation degree of the lubricant is in the range of 4% by mass or more and 13.8% by mass or less, the base oil from the thickener is contained even if the lubricant contains an organic molybdenum compound. It is difficult for the seepage to be inhibited, and the base oil can be stably supplied to the lubrication target portion (particularly, the contact portion between the external gear and the wave generator). As described above, the lubricant can stably supply the base oil to the lubrication target portion by the exudation from the thickener while exhibiting the excellent friction reducing effect of the organic molybdenum compound. The lifetime of the apparatus can be extended.

The gear device of this application example includes an internal gear,
An external gear that oscillates and rotates while internally meshing with the internal gear;
A lubricant disposed between the internal gear and the external gear,
The lubricant includes a base oil, a thickener, and an organic molybdenum compound, and has a degree of oil separation within a range of 4% by mass to 13.8% by mass.

  According to such a gear device, since the lubricant disposed in the lubrication target portion between the internal gear and the external gear contains the organic molybdenum compound, the friction in the lubrication target portion is effectively reduced. Can be reduced. In addition, since the oil separation degree of the lubricant is in the range of 4% by mass or more and 13.8% by mass or less, the base oil from the thickener is contained even if the lubricant contains an organic molybdenum compound. The exudation becomes difficult to be inhibited, and the base oil can be stably supplied to the lubrication target portion. As described above, the lubricant can stably supply the base oil to the lubrication target portion by the exudation from the thickener while exhibiting the excellent friction reducing effect of the organic molybdenum compound. The lifetime of the apparatus can be extended.

It is a side view showing a schematic structure of a robot concerning an embodiment of the present invention. It is a longitudinal cross-sectional view which shows the gear apparatus which concerns on 1st Embodiment of this invention. It is a front view of the gear apparatus shown in FIG. It is a longitudinal cross-sectional view which shows the gear apparatus which concerns on 2nd Embodiment of this invention. It is a disassembled perspective view which shows the gear apparatus which concerns on 3rd Embodiment of this invention. It is a longitudinal cross-sectional view of the gear apparatus shown in FIG. It is a graph which shows the relationship between the oil separation degree of a lubrication agent, and the lifetime of a gear apparatus. 2 is an enlarged photograph showing a state of an organomolybdenum compound contained in a lubricant according to Example 1. FIG. 6 is an enlarged photograph showing a state of an organomolybdenum compound contained in a lubricant according to Comparative Example 3.

  Hereinafter, a robot and a gear device of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

1. Robot First, an embodiment of the robot of the present invention will be briefly described.

  FIG. 1 is a side view showing a schematic configuration of a robot according to an embodiment of the present invention. In the following, for convenience of explanation, the upper side in FIG. 1 is referred to as “upper” and the lower side is referred to as “lower”. Further, the base side in FIG. 1 is referred to as “base end side”, and the opposite side (end effector side) is referred to as “tip side”. Further, the vertical direction in FIG. 1 is defined as “vertical direction”, and the horizontal direction is defined as “horizontal direction”.

  A robot 100 shown in FIG. 1 is, for example, a robot used for operations such as feeding, removing, transporting, and assembling precision instruments and parts (objects) constituting the precision equipment. As shown in FIG. 1, the robot 100 includes a base 110, a first arm 120, a second arm 130, a work head 140, an end effector 150, and a wiring routing unit 160. . Hereinafter, each part of the robot 100 will be briefly described.

  The base 110 is fixed to a floor surface (not shown) with bolts or the like, for example. A control device 190 that performs overall control of the robot 100 is installed inside the base 110. In addition, a first arm 120 is connected to the base 110 so as to be rotatable around a first axis J <b> 1 (rotating axis) along the vertical direction with respect to the base 110.

  Here, in the base 110, a motor 170 that is a first motor such as a servo motor that generates a driving force for rotating the first arm 120, and a first reduction device that decelerates the rotation of the driving force of the motor 170. A driving source having a gear device 10 is installed. The input shaft of the gear device 10 is connected to the rotation shaft of the motor 170, and the output shaft of the gear device 10 is connected to the first arm 120. Therefore, when the motor 170 is driven and the driving force is transmitted to the first arm 120 via the gear device 10, the first arm 120 rotates in the horizontal plane around the first axis J1 with respect to the base 110. To do.

  A second arm 130 is connected to the distal end portion of the first arm 120 so as to be rotatable about a second axis J2 (rotating axis) along the vertical direction with respect to the first arm 120. Although not shown in the figure, the second arm 130 has a second motor that generates a driving force for rotating the second arm 130 and a second power reducer that decelerates the rotation of the driving force of the second motor. Is installed. Then, when the driving force of the second motor is transmitted to the second arm 130 via the second reduction gear, the second arm 130 rotates in the horizontal plane around the second axis J2 with respect to the first arm 120. To do.

  A work head 140 is disposed at the tip of the second arm 130. The working head 140 has a spline shaft 141 inserted through a spline nut and a ball screw nut (both not shown) arranged coaxially at the tip of the second arm 130. The spline shaft 141 can rotate around the axis J3 with respect to the second arm 130 and can move (elevate) in the vertical direction.

  Although not shown, a rotation motor and a lifting motor are disposed in the second arm 130. The driving force of the rotary motor is transmitted to the spline nut by a driving force transmission mechanism (not shown), and when the spline nut rotates forward and backward, the spline shaft 141 rotates forward and backward about the axis J3 along the vertical direction.

  On the other hand, the driving force of the lifting motor is transmitted to the ball screw nut by a driving force transmission mechanism (not shown), and when the ball screw nut rotates forward and backward, the spline shaft 141 moves up and down.

  An end effector 150 is connected to the tip (lower end) of the spline shaft 141. The end effector 150 is not particularly limited, and examples thereof include an object that grips the object to be conveyed and an object that processes the object to be processed.

  A plurality of wires connected to each electronic component (for example, a second motor, a rotary motor, a lifting motor, etc.) arranged in the second arm 130 are tubular wires that connect the second arm 130 and the base 110. It is routed into the base 110 through the routing unit 160. Further, the plurality of wirings are collected in the base 110, and are routed to the control device 190 installed in the base 110 together with wirings connected to the motor 170 and an encoder (not shown).

  As described above, the robot 100 includes the base 110 that is the first member, the first arm 120 that is the second member provided to be rotatable with respect to the base 110, the base 110, and the first A gear device 10 that transmits a driving force from one side of the arm 120 to the other side.

  The first arm 120 and the second arm 130 may be collectively regarded as a “second member”. In addition to the first arm 120 and the second arm 130, the “second member” may further include a work head 140 and an end effector 150.

  In the present embodiment, the first reduction gear is configured by the gear device 10, but the second reduction device may be configured by the gear device 10, and the first reduction gear and the second reduction gear may be provided. Both may be constituted by the gear unit 10. When the second reduction gear is configured by the gear device 10, the first arm 120 may be regarded as a “first member” and the second arm 130 may be regarded as a “second member”. Moreover, it replaces with the gear apparatus 10 and may use the gear apparatus 10B or 200 mentioned later.

  In the present embodiment, the motor 170 and the gear device 10 are provided on the base 110, but the motor 170 and the gear device 10 may be provided on the first arm 120. In this case, the output shaft of the gear device 10 may be connected to the base 110.

2. Gear Device Hereinafter, an embodiment of a gear device of the present invention will be described.

<First Embodiment>
FIG. 2 is a longitudinal sectional view showing the gear device according to the first embodiment of the present invention. FIG. 3 is a front view of the gear device shown in FIG. In each drawing, for convenience of explanation, the dimensions of each part are appropriately exaggerated as necessary, and the dimension ratio between the parts does not necessarily match the actual dimension ratio.

  A gear device 10 shown in FIG. 2 is a wave gear device, and is used, for example, as a speed reducer. The gear device 10 includes a gear device main body 1 and a case 5 that houses the gear device main body 1, and these are integrated. Here, the lubricant G is disposed in the case 5 of the gear device 10. Hereinafter, each part of the gear device 10 will be described. Note that the case 5 may be provided as necessary and may be omitted.

(Gear device body)
The gear device main body 1 includes a rigid gear 2 that is an internal gear, a flexible gear 3 that is a cup-type external gear disposed inside the rigid gear 2, and an inner side of the flexible gear 3. A wave generator 4.

  In the present embodiment, the rigid gear 2 is fixed (connected) to the base 110 (first member) of the robot 100 described above via the case 5, and the flexible gear 3 is connected to the first arm 120 ( The wave generator 4 is connected to the rotating shaft of the motor 170 arranged on the base 110 of the robot 100 described above.

  When the rotation shaft of the motor 170 rotates (that is, when a driving force is generated), the wave generator 4 rotates at the same rotation speed as the rotation shaft of the motor 170. Since the rigid gear 2 and the flexible gear 3 have different numbers of teeth, the meshing positions of the rigid gear 2 and the flexible gear 3 rotate relatively around the axis a while moving in the circumferential direction. In the present embodiment, since the number of teeth of the rigid gear 2 is larger than the number of teeth of the flexible gear 3, the flexible gear 3 can be rotated at a rotational speed lower than the rotational speed of the rotating shaft of the motor 170. . That is, it is possible to realize a reduction gear having the wave generator 4 on the input shaft side and the flexible gear 3 on the output shaft side.

  Depending on the form of the case 5, the gear device 10 can be used as a speed reducer even when the flexible gear 3 is fixed (connected) to the base 110 and the rigid gear 2 is connected to the first arm 120. . Further, even if the rotating shaft of the motor 170 is connected to the flexible gear 3, the gear device 10 can be used as a speed reducer. In this case, the wave generator 4 is fixed (connected) to the base 110 and is rigid. The gear 2 may be connected to the first arm 120. Further, when the gear device 10 is used as a speed increaser (when the flexible gear 3 is rotated at a rotational speed higher than the rotational speed of the rotating shaft of the motor 170), the relationship between the input side and the output side described above is reversed. You can do it.

  As shown in FIGS. 2 and 3, the rigid gear 2 is a gear formed of a rigid body that does not substantially bend in the radial direction, and is a ring-shaped internal gear having internal teeth 23. In the present embodiment, the rigid gear 2 is a spur gear. That is, the internal teeth 23 have tooth lines parallel to the axis a. In addition, the tooth stripe of the internal tooth 23 may be inclined with respect to the axis line a. That is, the rigid gear 2 may be a helical gear or a helical gear.

  As shown in FIGS. 2 and 3, the flexible gear 3 is inserted inside the rigid gear 2. The flexible gear 3 is a gear having flexibility that can be bent and deformed in the radial direction, and has external teeth 33 (teeth) that mesh with the internal teeth 23 of the rigid gear 2. Further, the number of teeth of the flexible gear 3 is smaller than the number of teeth of the rigid gear 2. Thus, the reduction gear can be realized by the number of teeth of the flexible gear 3 and the rigid gear 2 being different from each other.

  In the present embodiment, the flexible gear 3 has a cup shape having an opening 36 with one end (the right end in FIG. 2) opened in the direction of the axis a, and the opening 36 toward the other end. External teeth 33 are formed. Here, the flexible gear 3 is connected to a cylindrical (more specifically, cylindrical) barrel 31 (tubular) around the axis a and the other end of the barrel 31 in the axis a direction. And a bottom 32. Accordingly, the end portion of the opening portion 36 is easily bent in the radial direction as compared with the bottom portion 32 of the body portion 31, so that a good bending engagement of the flexible gear 3 with the rigid gear 2 can be realized. Furthermore, the rigidity of the bottom 32 to which the shaft 62 (for example, the output shaft) is connected can be increased. For this reason, the gear unit 10 has a very small backlash and is suitable for applications that repeat reversal, and since the ratio of the number of simultaneously meshing teeth is large, the force applied to one tooth is small, and the high torque capacity You can also get Since it can be used for such severe applications, the lubricant is required to have high lubrication performance.

  As shown in FIGS. 2 and 3, the wave generator 4 is disposed inside the flexible gear 3 and is rotatable around the axis a. Then, the wave generator 4 deforms the cross section of the opening 36 of the flexible gear 3 into an oval shape or an oval shape having the major axis La and the minor axis Lb, and the outer teeth 33 are transformed into the inner teeth of the rigid gear 2. 23. Here, the flexible gear 3 and the rigid gear 2 are engaged with each other inside and outside so as to be rotatable around the same axis a.

  In the present embodiment, the wave generator 4 includes a cam 41 and a bearing 42 attached to the outer periphery of the cam 41. The cam 41 includes a shaft portion 411 that rotates around the axis line a, and a cam portion 412 that protrudes outward from one end portion of the shaft portion 411.

  A shaft 61 (for example, an input shaft) is connected to the shaft portion 411. The outer peripheral surface of the cam portion 412 is elliptical or oval when viewed from the direction along the axis a. The bearing 42 includes a flexible inner ring 421 and an outer ring 423, and a plurality of balls 422 disposed therebetween. Here, the inner ring 421 is fitted into the outer peripheral surface of the cam portion 412 of the cam 41 and is elastically deformed into an elliptical shape or an oval shape along the outer peripheral surface of the cam portion 412. Accordingly, the outer ring 423 is also elastically deformed into an elliptical shape or an oval shape. Moreover, the outer peripheral surface of the inner ring 421 and the inner peripheral surface of the outer ring 423 each have a raceway surface that rolls the plurality of balls 422 while guiding them along the circumferential direction. Further, the plurality of balls 422 are held by a holder (not shown) so as to keep the interval in the circumferential direction constant. In the bearing 42, grease (not shown) is arranged. This grease may be the same as or different from the lubricant G described later.

  In such a wave generator 4, as the cam 41 rotates around the axis a, the direction of the cam portion 412 changes, and accordingly, the outer peripheral surface of the outer ring 423 also deforms, and the rigid gear 2 and the flexible gear 3 are moved in the circumferential direction.

  The rigid gear 2, the flexible gear 3, and the wave generator 4 are each preferably made of a metal material, and are particularly excellent in mechanical characteristics and workability and relatively inexpensive. Therefore, it is preferable to use an iron-based material. Although it does not specifically limit as this iron-type material, For example, it is preferable that it is any one of cast iron, nickel chromium molybdenum steel, chromium molybdenum steel (SCM), maraging steel, and precipitation hardening type stainless steel. In particular, when chromium molybdenum steel (for example, SCM435) is used for the rigid gear 2, it has a good fatigue strength even if it has a lower hardness than, for example, spheroidal graphite cast iron (ductile cast iron). Can be achieved. Further, if nickel chrome molybdenum steel (for example, SNCM439) is used for the flexible gear 3, the hardness can be made higher than that of the rigid gear 2 using chrome molybdenum steel. Thus, the life of the gear device 10 can be further extended. The rigid gear 2 and the wave generator 4 are substantially rigid bodies, and can be made of a ceramic material or the like. However, from the balance of strength with the flexible gear 3, a metal material is used. It is preferable to use it. If the difference in strength between these members is too large, the member on the lower strength side is extremely easily worn, and as a result, the life of the gear unit 10 is shortened.

(Case)
The case 5 shown in FIG. 2 supports a substantially plate-like lid body 11 that supports a shaft 61 (for example, an input shaft) through a bearing 13 and a shaft 62 (for example, an output shaft) through a bearing 14. And a cup-shaped main body 12. Here, the lid body 11 and the main body 12 are connected (fixed) to form a space, and the gear device main body 1 described above is accommodated in the space. The rigid gear 2 of the gear device main body 1 described above is fixed to at least one of the lid body 11 and the main body 12 by, for example, screwing or the like.

  The inner wall surface 111 of the lid 11 has a shape that extends in a direction perpendicular to the axis a so as to cover the opening 36 of the flexible gear 3. Further, the inner wall surface 121 of the main body 12 has a shape along the outer peripheral surface and the bottom surface of the flexible gear 3. Such a case 5 is fixed to the base 110 of the robot 100 described above. Here, the lid body 11 is a separate body from the base 110 and may be fixed to the base 110 by, for example, screwing or the like, or may be integral with the base 110. Moreover, it does not specifically limit as a constituent material of case 5 (the cover body 11 and the main body 12), For example, a metal material, a ceramic material, etc. are mentioned.

(lubricant)
The lubricant G is grease (semi-solid lubricant), between the rigid gear 2 that is a lubrication target part and the flexible gear 3 (meshing part), and the flexible gear 3 that is a lubrication target part. It is arranged at least one of the wave generators 4 (contact portion / sliding portion) (hereinafter also simply referred to as “lubrication target portion”). Thereby, the friction of the said lubrication object part can be reduced.

  This lubricant G contains a base oil and a thickener. Examples of the base oil include paraffinic and naphthenic mineral oils (refined mineral oils), synthetic oils such as polyolefins, esters, and silicones. One of these may be used alone, or two or more may be used in combination. Can be used. Examples of the thickener include soaps such as calcium soap, calcium composite soap, sodium soap, aluminum soap, lithium soap, lithium composite soap, and polyurea, sodium terephthalate, polytetrafluoroethylene (PTFE). Non-soap type such as organic bentonite and silica gel can be used, and one of these can be used alone or in combination of two or more. As described above, the lubricant G (grease) containing the base oil and the thickener as a composition holds the base oil by complicatedly intertwining the three-dimensional structure formed by the thickener. Lubricates by letting out the base oil little by little.

  Here, the content of the base oil in the lubricant G is 75% by mass or more and 85% by mass or less, and the content of the thickener in the lubricant G is 10% by mass or more and 20% by mass or less. Is preferred. Thereby, the lubrication performance of the lubricant G can be enhanced.

  Further, the lubricant G contains an organic molybdenum compound. The organomolybdenum compound functions as a solid lubricant or extreme pressure agent. Thereby, the friction in the lubrication target portion can be effectively reduced, and seizure and scuffing can be effectively prevented even when the lubrication target portion is in the extreme pressure lubrication state. In particular, the organomolybdenum compound exhibits extreme pressure and wear resistance equivalent to those of molybdenum disulfide, and is excellent in oxidation stability as compared with molybdenum disulfide. Therefore, the life of the lubricant G can be extended.

  Here, the organomolybdenum compound is added to the lubricant G in the form of particles, but when used in the gear device 10, the organic molybdenum compound has an effect of forming a coating on the lubrication target portion and lowering the friction coefficient by being decomposed. For this reason, the organomolybdenum compound is suitable for lubrication of the meshing portion of the rigid gear 2 and the flexible gear 3 that mesh with very small backlash and the extremely small gap between the flexible gear 3 and the wave generator 4. Yes. On the other hand, in the case of molybdenum disulfide, in order to reduce the friction in the lubrication target part, the particle state must be maintained even if it adheres to the lubrication target part, and the rigid gear 2 and the flexible gear 3 is not suitable for lubrication in the meshing portion with the contact portion 3 or the contact portion between the flexible gear 3 and the wave generator 4.

  Further, the content of the organomolybdenum compound in the lubricant G is preferably, for example, from 1% by mass to 5% by mass. As a result, the performance of the organic molybdenum compound as an extreme pressure agent is easily exhibited, and the characteristics of the lubricant G are significantly improved. In addition to the organic molybdenum compound, other extreme pressure agents such as zinc dialkyldithiophosphate may be used in combination as the extreme pressure agent or solid lubricant.

  Here, the average particle diameter of the organomolybdenum compound is generally as large as about 10 μm. Therefore, simply adding an organomolybdenum compound to the lubricant G hinders the exudation of the base oil from the thickener of the lubricant G due to the influence of the particles of the organomolybdenum compound, resulting in insufficient lubrication of the lubrication target part. May be invited. For example, since the gap between the flexible gear 3 and the wave generator 4 is small, it is difficult to supply the entire grease, and it is important that the base oil that exudes from the thickener is supplied. Therefore, it is easy to cause insufficient lubrication.

  Therefore, the oil separation degree of the lubricant G is in the range of 4% by mass to 13.8% by mass. This makes it difficult to prevent the base oil from seeping out from the thickener of the lubricant G, and stably supplies the base oil to the lubrication target portion (particularly the contact portion between the flexible gear 3 and the wave generator 4). Can be supplied. Thus, the lubricant G can stably supply the base oil to the lubrication target part by the base oil oozing out from the thickener while exhibiting the excellent friction reducing effect by the organomolybdenum compound. As a result, the life of the gear device 10 can be extended. The “oil separation degree” is an index indicating the ability to exude the base oil from the thickener, and is measured according to the measurement method defined in JIS K2220.

  Here, from the viewpoint of enhancing the effect due to the oil separation degree of the lubricant G as described above, the average particle size of the organic molybdenum compound (solid lubricant or extreme pressure agent) added to the lubricant G is 1 μm or more and 10 μm or less. It is preferable to be within the range.

  Further, the oil separation degree of the lubricant G may be in the range of 4% by mass or more and 13.8% by mass or less, but is preferably in the range of 6% by mass or more and 11% by mass or less. More preferably, it is in the range of 10% by mass or less (see FIG. 7). Thereby, the lifetime of the gear apparatus 10 can be made longer.

  Here, the oil separation degree tends to increase as the consistency increases (that is, becomes softer), and has a certain degree of correlation with the consistency. Therefore, for example, the lubricant G having a desired oil separation degree can be obtained by adjusting the consistency according to the blending ratio of the base oil and the thickener.

  The consistency of the lubricant G is preferably in the range of 325 to 365, more preferably in the range of 330 to 360, and still more preferably in the range of 335 to 355. . Thereby, the lubricant G can be easily retained on the lubrication target portion. Further, there is an advantage that the oil separation degree of the lubricant G can be easily set within the above-described range. On the other hand, if the consistency of the lubricant G is too small, it is difficult to select the base oil and the thickener that fall within the above-mentioned range of oil separation, and the fluidity of the lubricant G becomes insufficient, resulting in a rigid gear. It becomes difficult to sufficiently supply the lubricant G to the meshing part between the flexible gear 3 and the flexible gear 3. On the other hand, if the consistency of the lubricant G is too large, the fluidity of the lubricant G becomes too high, and the lubricant is moved to the outside of the gear device 10 (for example, an unintentional position in the case 5 or the outside of the case 5). Since G easily leaks, the supply of the lubricant G to the meshing portion between the rigid gear 2 and the flexible gear 3 becomes unstable, and on the contrary, poor lubrication tends to occur at the meshing portion. “Consistency” is an index representing the hardness of grease, and is measured in accordance with a measurement method defined in JIS K2220.

  The dropping point of the lubricant G is preferably in the range of 248 ° C. or higher and 270 ° C. or lower. Thereby, the heat resistance of the lubricant G can be made excellent while optimizing the consistency of the lubricant G. “Drip point” refers to the temperature at which the grease structure is destroyed and changes from a semi-solid to a liquid state, and is measured according to the measurement method defined in JIS K2220.

  Here, the thickener used for the lubricant G is preferably lithium composite soap among the thickeners described above. That is, it is preferable that the thickener used for the lubricant G contains a lithium composite soap. Thereby, the dropping point of the lubricant G can be increased, and the heat resistance of the lubricant G can be improved. In addition, when using lithium composite soap as a thickener, you may use lithium composite soap independently as a thickener, and may mix and use another thickener and lithium composite soap. When other thickeners and lithium composite soap are mixed and used, the content of lithium composite soap in the total thickener is preferably 70% by mass or more.

  In addition to the base oil, thickener, and extreme pressure agent (organic molybdenum compound), the lubricant G includes additives such as antioxidants and rust inhibitors, graphite, molybdenum disulfide, polytetra A solid lubricant such as fluoroethylene (PTFE) may be included.

  As described above, the gear device 10 includes the rigid gear 2 that is an internal gear, the flexible gear 3 that is a flexible external gear partially meshed with the rigid gear 2, and the flexible gear 3. A wave generator 4 that contacts the inner peripheral surface and moves the meshing position of the rigid gear 2 and the flexible gear 3 in the circumferential direction, and between the rigid gear 2 and the flexible gear 3 and the flexible gear 3. And a lubricant G disposed in at least one (the lubrication target part) between the wave generator 4 and the wave generator 4. Here, one of the two members (the rigid gear 2 and the flexible gear 3 in the present embodiment) out of the rigid gear 2, the flexible gear 3, and the wave generator 4 (the rigid gear in the present embodiment). The gear 2) is connected to the base 110 (first member), and the other member (the flexible gear 3 in this embodiment) is connected to the first arm 120 (second member). Yes. In particular, the lubricant G includes a base oil, a thickener, and an organomolybdenum compound, and has a degree of oil separation in the range of 4% by mass to 13.8% by mass.

  According to such a gear device 10, since the lubricant G arranged in the lubrication target portion contains the organic molybdenum compound, the lubrication target portion (particularly, the meshing portion between the rigid gear 2 and the flexible gear 3). Friction can be effectively reduced. In addition, when the oil separation degree of the lubricant G is in the range of 4% by mass or more and 13.8% by mass or less, the exudation of the base oil from the thickener of the lubricant G is hardly inhibited. The base oil can be stably supplied to the lubrication target portion (particularly, the contact portion between the flexible gear 3 and the wave generator 4). Thus, the lubricant G can stably supply the base oil to the lubrication target part by the base oil oozing out from the thickener while exhibiting the excellent friction reducing effect by the organomolybdenum compound. As a result, the life of the gear device 10 can be extended.

Second Embodiment
Next, a second embodiment of the present invention will be described.
FIG. 4 is a longitudinal sectional view showing a gear device according to the second embodiment of the present invention.

  The present embodiment is the same as the first embodiment described above except that the configuration of the external gear and the configuration of the case accompanying it are different. In the following description, the present embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted. In FIG. 4, the same reference numerals are given to the same configurations as those in the above-described embodiment.

  A gear device 10B shown in FIG. 4 includes a gear device main body 1B and a case 5B housing the gear device main body 1B. Case 5B may be omitted.

  The gear device 10 </ b> B includes a flexible gear 3 </ b> B that is a hat-type (edge-cap type) external gear disposed inside the rigid gear 2. This flexible gear 3 </ b> B has a flange portion 32 </ b> B (connection portion) that is connected to one end portion of the cylindrical body portion 31 and protrudes on the opposite side to the axis line “a”. An output shaft (not shown) is attached to the flange portion 32B.

  The case 5B includes a substantially plate-like lid 11B that supports a shaft 61 (for example, an input shaft) via a bearing 13, and the cross roller bearing 18 that is attached to the flange portion 32B of the flexible gear 3B described above. And having.

  Here, the lid 11B is fixed to one side (right side in FIG. 4) of the rigid gear 2 by, for example, screwing or the like. Moreover, the cross roller bearing 18 has the inner ring | wheel 15, the outer ring | wheel 16, and the several roller 17 arrange | positioned among these. And the inner ring | wheel 15 is provided along the outer periphery of the trunk | drum 31 of the flexible gearwheel 3, and is being fixed to the other side (left side in FIG. 4) of the rigid gearwheel 2 by screwing etc., for example. On the other hand, the outer ring 16 is fixed to the surface of the flange portion 32B of the flexible gear 3B described above on the body portion 31 side by, for example, screwing or the like.

  Further, the inner wall surface 111B of the lid 11B has a shape that expands in a direction perpendicular to the axis a so as to cover the opening 36 of the flexible gear 3B. Further, the inner wall surface 151 of the inner ring 15 of the cross roller bearing 18 has a shape along the outer peripheral surface of the trunk portion 31 of the flexible gear 3B.

  The gear device 10B as described above is disposed in at least one (the lubrication target portion) between the rigid gear 2 and the flexible gear 3B and between the flexible gear 3B and the wave generator 4. Lubricant G is included. Here, one member of the rigid gear 2, the flexible gear 3B, and the wave generator 4 is connected to the base 110 (first member), and the other member is the first arm 120 (first member). 2 members). In particular, as described in the first embodiment, the lubricant G includes an organomolybdenum compound and has a degree of oil separation in the range of 4% by mass to 13.8% by mass.

  According to the second embodiment as described above, the life of the gear device 10B can be extended.

<Third Embodiment>
Next, a third embodiment of the present invention will be described.

  FIG. 5 is an exploded perspective view showing a gear device according to a third embodiment of the present invention. 6 is a longitudinal sectional view of the gear device shown in FIG.

  In the following description, the present embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.

  A gear device 200 shown in FIGS. 5 and 6 includes a main body 202 having a cylindrical outer shape. A first rotating shaft 203 is provided on one side of the main body 202 in the axial direction, and a second rotating shaft 204 is provided on the other side of the main body 202 in the axial direction. The first rotating shaft 203 and the second rotating shaft 204 rotate around the same central axis 205. Here, the central axis 205 is arranged on the same line as the axis of the main body 202. When the first rotating shaft 203 is rotated with the main body portion 202 fixed, the rotation is decelerated by a mechanism in the main body portion 202 as will be described later and output from the second rotating shaft 204. That is, the first rotating shaft 203 is an input shaft that rotates at a high speed, and the second rotating shaft 204 is an output shaft that rotates at a low speed.

  As shown in FIG. 5, the gear device 200 includes a cylindrical ring gear 206 having a hollow portion 206c. A plurality of gear teeth 206 a are formed on the inner periphery of the ring gear 206. A first revolving gear 207 and a second revolving gear 208 having an outer periphery slightly smaller than the inner periphery of the ring gear 206 are installed inside the ring gear 206. A plurality of gear teeth 207a smaller than the number of gear teeth 206a is arranged on the outer periphery of the first revolution gear 207, and the same number of teeth as the gear teeth 207a is arranged on the outer periphery of the second revolution gear 208. A plurality of gear teeth 208a are arranged. The gear teeth 207a and the gear teeth 208a mesh with the gear teeth 206a. Here, a lubricant similar to the lubricant G of the first embodiment described above is formed in a meshing portion between the ring gear 206 as an internal gear and the first revolving gear 207 and the second revolving gear 208 as external gears. G is arranged.

  A shaft hole 207 b is provided at the center of the first revolution gear 207, and similarly, a shaft hole 208 b is provided at the center of the second revolution gear 208. A first bearing 209 is installed in the shaft hole 207b, and similarly, a second bearing 210 is installed in the shaft hole 208b.

  The first rotating shaft 203 is provided with a first eccentric cam 211 and a second eccentric cam 212 which are circular cams that are eccentric by the same amount on the opposite sides with respect to the central shaft 205. The first eccentric cam 211 is installed on the inner ring of the first bearing 209, and similarly, the second eccentric cam 212 is installed on the inner ring of the second bearing 210. As a result, the center shaft 205 is located between the portion where the gear teeth 207a mesh with the gear teeth 206a and the portion where the gear teeth 208a mesh with the gear teeth 206a.

  The first revolving gear 207 is provided with first through holes 207 c at four locations on concentric circles centering on the center of the first revolving gear 207. Similarly, the second revolving gear 208 is provided with second through holes 208 c at four locations on a concentric circle centered on the center of the second revolving gear 208. A through pin 213 for taking out the rotation movement of the first revolving gear 207 is inserted into each first through hole 207c and each second through hole 208c. A substantially cylindrical first elastic portion 214 having elasticity is fitted into the inner peripheral wall of each first through hole 207c by press-fitting. Similarly, a substantially cylindrical second elastic portion 215 having elasticity is fitted into the inner peripheral wall of each second through-hole 208c by press-fitting. Here, the penetration pin 213 penetrates the inside of the first elastic part 214 and the second elastic part 215.

  Each penetrating pin 213 is attached to the disc-shaped lower lid plate 216 on the first rotating shaft 203 side of the main body 202, and is attached to the disc-shaped upper lid plate 218 by a nut 217 on the second rotating shaft 204 side. It is fixed. The lower cover plate 216 and the upper cover plate 218 are arranged along the axial direction of the central shaft 205 and sandwich the ring gear 206 with a gap so as to be rotatable with respect to the ring gear 206.

  A center hole 216a into which the first rotation shaft 203 is inserted is formed at the center of the lower lid plate 216. One end portions of the first rotating shaft 203 on the first eccentric cam 211 side and the second eccentric cam 212 side protrude from the lower lid plate 216 into the main body portion 202, and the other end portion of the first rotating shaft 203 is the lower lid plate 216. Protrudes from the main body 202 to the outside. A second rotating shaft 204 is fixed at the center of the upper lid plate 218. As the upper lid plate 218 rotates, the rotational torque of the upper lid plate 218 is transmitted to the second rotating shaft 204.

  As described above, the gear device 200 includes the ring gear 206, which is an internal gear, and the first revolving gear 207 and the second revolving gear 208, which are external gears that oscillate and rotate while meshing with the ring gear 206. And a lubricant G disposed between the ring gear 206 and the first revolving gear 207 and the second revolving gear 208 (parts to be lubricated). The lubricant G includes a base oil, a thickener, and an organic molybdenum compound, and has a degree of oil separation in the range of 4% by mass to 13.8% by mass. Thereby, lifetime improvement of the gear apparatus 200 can be achieved.

  The robot and gear device of the present invention have been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each part is an arbitrary configuration having the same function. Can be substituted. In addition, any other component may be added to the present invention.

  In the above-described embodiment, the base provided in the robot is the “first member”, the first arm is the “second member”, and the gear device that transmits the driving force from the first member to the second member has been described. The present invention is not limited to this, and the nth (n is an integer of 1 or more) arm is the “first member”, the (n + 1) th arm is the “second member”, and the nth arm and the (n + 1) th arm The present invention can also be applied to a gear device that transmits a driving force from one arm to the other. The present invention can also be applied to a gear device that transmits a driving force from the second member to the first member.

  In the above-described embodiment, the robot horizontal articulated robot has been described. However, the robot of the present invention is not limited to this, for example, the number of joints of the robot is arbitrary, and is also applicable to a vertical articulated robot. Is possible.

  In the above-described embodiment, the case where the gear device is incorporated into the robot has been described as an example. However, the gear device of the present invention applies a driving force from one side to the other side of the first member and the second member that rotate with respect to each other. It can be used by being incorporated into various devices having a transmission structure.

Hereinafter, specific examples of the present invention will be described.
1. Production of gear device (reduction gear) (Example 1)
A gear device having the structure shown in FIG. 2 was manufactured.

  Here, the manufactured gear device had an outer diameter φ70 of the internal gear, an inner diameter of the internal gear, an outer diameter of the external gear (meshing reference circle diameter) φ53, and a reduction ratio 80. Further, chromium molybdenum steel (SCM435) was used as the constituent material of the internal gear, and nickel chromium molybdenum steel (SNCM439) was used as the constituent material of the external gear.

  Further, as lubricant, base oil (mineral oil): 80% by mass, lithium (Li) composite soap as thickener: 15% by mass, organic molybdenum compound (organic Mo) as extreme pressure agent: 4% by mass, 2 , 6-di-tert-butyl-4-cresol: 1% by weight, a grease having a consistency of 325, an oil separation of 4% by weight, and a dropping point of 270 ° C. was used.

(Examples 2-5, Comparative Examples 1-4)
A gear device was manufactured in the same manner as in Example 1 except that the thickening degree, oil separation degree, dropping point, and type of thickening agent were as shown in Table 1.

  Here, the lubricants used in Examples 2 to 5 and Comparative Examples 1 and 2 have the same types of constituents as the lubricant used in Example 1, but the base oil (mineral oil) is increased. The compounding ratio with the agent is different. In addition, the lubricants used in Comparative Examples 3 and 4 each used lithium (Li) soap as a thickener, and appropriately adjusted the blending ratio of the constituent components.

2. Evaluation As described above. For each gear device obtained in the above, continuous operation was performed at an input shaft rotational speed (input shaft rotational speed) of 3000 rpm and an average load torque of 70 Nm, and the total rotational speed of the input shaft until the gear device was damaged was measured. The results are also shown in Table 1 as the lifetime.

  As can be seen from Table 1, each example has a significantly longer life than each comparative example.

  FIG. 7 is a graph showing the relationship between the oil separation degree of the lubricant and the life of the gear unit. Regarding Examples 2 to 5 and Comparative Examples 1 and 2 having the same component type, the relationship between the oil separation degree and the service life is as shown in FIG. It can be seen that the life of the gear unit is significantly increased when it is within the range of mass%.

  FIG. 8 is an enlarged photograph showing the state of the organomolybdenum compound contained in the lubricant according to Example 1. FIG. 9 is an enlarged photograph showing the state of the organomolybdenum compound contained in the lubricant according to Comparative Example 3. When Example 1 and Comparative Example 3 were compared, even if the particle size of the organomolybdenum compound was the same as shown in FIGS. 8 and 9, Example 1 was compared with Comparative Example 3 from the results in Table 1. It can be seen that the service life is much longer.

DESCRIPTION OF SYMBOLS 1 ... Gear apparatus main body, 1B ... Gear apparatus main body, 2 ... Rigid gear (internal gear), 3 ... Flexible gear (external gear), 3B ... Flexible gear (external gear), 4 ... Wave generation 5 ... case 5B ... case 10 ... gear device 10B ... gear device 11 ... lid body 11B ... lid body 12 ... main body 13 ... bearing 14 ... bearing 15 ... inner ring 16 ... outer ring 17 ... Roller, 18 ... Cross roller bearing, 23 ... Internal teeth, 31 ... Body, 32 ... Bottom, 32B ... Flange, 33 ... External teeth, 36 ... Opening, 41 ... Cam, 42 ... Bearing, 61 ... Shaft , 62 ... shaft, 100 ... robot, 110 ... base, 111 ... inner wall surface, 111B ... inner wall surface, 120 ... first arm, 121 ... inner wall surface, 130 ... second arm, 140 ... work head, 141 ... spline shaft 150 ... End effector 151 ... Inner wall surface DESCRIPTION OF SYMBOLS 160 ... Wiring routing part, 170 ... Motor, 190 ... Control apparatus, 200 ... Gear apparatus, 202 ... Main-body part, 203 ... 1st rotating shaft, 204 ... 2nd rotating shaft, 205 ... Center axis, 206 ... Ring gear, 206a ... gear teeth, 206c ... cavity, 207 ... first revolving gear, 207a ... gear teeth, 207b ... shaft hole, 207c ... first through hole, 208 ... second revolving gear, 208a ... gear teeth, 208b ... shaft hole, 208c ... second through hole, 209 ... first bearing, 210 ... second bearing, 211 ... first eccentric cam, 212 ... second eccentric cam, 213 ... through pin, 214 ... first elastic part, 215 ... second elasticity Part, 216 ... lower cover plate, 216a ... center hole, 217 ... nut, 218 ... upper cover plate, 411 ... shaft part, 412 ... cam part, 421 ... inner ring, 422 ... ball, 423 ... outer ring, G ... lubricant, 1 ... first axis, J2 ... second shaft, J3 ... shaft, La ... major axis, Lb ... minor axis, a ... axis

Claims (8)

A first member;
A second member rotatably provided with respect to the first member;
A gear device that transmits a driving force from one side to the other side of the first member and the second member,
The gear device is
An internal gear,
A flexible external gear partially meshed with the internal gear;
A wave generator that contacts an inner peripheral surface of the external gear and moves a meshing position of the internal gear and the external gear in a circumferential direction;
A lubricant disposed between at least one of the internal gear and the external gear and between the external gear and the wave generator;
One of the internal gear, the external gear and the wave generator is connected to the first member, and the other is connected to the second member.
The lubricant includes a base oil, a thickener, and an organomolybdenum compound, and has a degree of oil separation in a range of 4% by mass to 13.8% by mass.   The robot according to claim 1, wherein the consistency of the lubricant is in a range of 325 to 365.   The robot according to claim 1, wherein a dropping point of the lubricant is in a range of 248 ° C. or more and 270 ° C. or less.   The robot according to any one of claims 1 to 3, wherein the thickener includes lithium composite soap.   The robot according to claim 1, wherein the internal gear is made of chromium molybdenum steel.   The robot according to claim 5, wherein the external gear is made of nickel chrome molybdenum steel. An internal gear,
A flexible external gear partially meshed with the internal gear;
A wave generator that contacts an inner peripheral surface of the external gear and moves a meshing position of the internal gear and the external gear in a circumferential direction;
A lubricant disposed between at least one of the internal gear and the external gear and between the external gear and the wave generator;
The lubricant includes a base oil, a thickener, and an organic molybdenum compound, and has a degree of oil separation within a range of 4% by mass to 13.8% by mass. . An internal gear,
An external gear that oscillates and rotates while internally meshing with the internal gear;
A lubricant disposed between the internal gear and the external gear,
The lubricant includes a base oil, a thickener, and an organic molybdenum compound, and has a degree of oil separation within a range of 4% by mass to 13.8% by mass. .

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