JP6848669B2 - Robots and gears - Google Patents

Description

The present invention relates to robots and gears.

In a robot including a robot arm including at least one arm, for example, a joint portion of the robot arm is driven by a motor, but in general, rotation due to a driving force (rotational force) from the motor is decelerated by a speed reducer. Is being done. As such a speed reducer, for example, a gear device such as the wave gear device described in Patent Document 1 is known.

The strain wave gearing described in Patent Document 1 includes a ring-shaped rigid internal gear, a ring-shaped flexible external gear, and the external gear partially connected to the internal gear in the radial direction. It is provided with a wave generator that meshes with the gear and moves the meshing position in the circumferential direction. The tooth surface portions of the internal gear and the external gear are filled with grease.

JP-A-2002-349681

In the strain wave gearing described in Patent Document 1, the internal gear and the external gear mesh with each other with extremely few backlashes. Conventionally, there has been a problem that the lubrication life of the lubricant in such a meshing portion is short, and when such a wave gear device is used for a robot, seizure, wear, etc. are likely to occur relatively early.

An object of the present invention is to provide a robot and a gear device capable of effectively improving the lubrication life of a lubricant used in the gear device.

The above object is achieved by the following invention.
The robot of the present invention includes the first member and
A second member rotatably provided with respect to the first member,
A gear device for transmitting a driving force from one side of the first member and the second member to the other side is provided.
The gear device
Internal and external teeth that are provided in the middle of the driving force transmission path and mesh with each other,
With a lubricant disposed between the internal teeth and the external teeth,
The average crystal grain size of the constituent material of the outer tooth is smaller than the average crystal grain size of the constituent material of the inner tooth.

According to such a robot, the crystal grain size of the outer teeth can be reduced to facilitate holding of the lubricant on the outer teeth. Therefore, the lubricant can be retained on the external teeth against the centrifugal force due to the rotation of the external teeth. On the other hand, the crystal grain size of the internal teeth can be increased to facilitate the flow of the lubricant along the internal teeth. Therefore, it is possible to reduce the bias and solidification of the lubricant on the internal teeth. Then, as described above, the two effects of the effect of retaining the lubricant on the outer teeth and the effect of reducing the bias and solidification of the lubricant on the inner teeth are synergistic, and the lubricant The lubrication life of the product can be effectively improved.

In the robot of the present invention, it is preferable that the average crystal grain size of the constituent material of the internal teeth is in the range of 20 μm or more and 150 μm or less.

This allows the lubricant to flow more effectively along the internal teeth. Further, when the internal teeth are made of metal, the mechanical strength of the internal teeth can be made excellent.

In the robot of the present invention, it is preferable that the average crystal grain size of the constituent material of the external tooth is in the range of 0.5 μm or more and 30 μm or less.

This allows the lubricant to be more effectively retained on the external teeth. Further, when the external teeth are made of metal, the mechanical strength of the external teeth can be made excellent.

In the robot of the present invention, it is preferable that the internal teeth and the external teeth are each made of a metal material.

In general, metals have excellent mechanical properties, can be machined relatively easily, and have high processing accuracy. Therefore, internal teeth and external teeth having excellent characteristics (mechanical strength, accuracy, etc.) can be easily realized.

In the robot of the present invention, it is preferable that the internal teeth are made of either cast iron or precipitation hardening stainless steel.

Thereby, an internal tooth having excellent characteristics (mechanical strength, accuracy, etc.) can be easily realized. In particular, cast iron and precipitation hardening stainless steel, respectively, can easily achieve an appropriate grain size that allows the lubricant to effectively flow along the internal teeth, and have an excellent balance between mechanical strength and workability. There is. Therefore, by constructing the internal teeth with either cast iron or precipitation hardening stainless steel, the mechanical strength of the internal teeth is improved, and the lubricant is more effectively applied along the internal teeth. Can be fluidized.

In the robot of the present invention, the external teeth are preferably made of any one of nickel chrome molybdenum steel, maraging steel and precipitation hardening stainless steel.

Thereby, an external tooth having excellent characteristics (mechanical strength, accuracy, etc.) can be easily realized. In particular, nickel-chromium molybdenum steel, maraging steel and precipitation hardening stainless steel, respectively, are easy to achieve appropriate grain boundaries that effectively hold the lubricant on the external teeth, and have mechanical strength and workability, respectively. Excellent balance. Therefore, by configuring the outer teeth with any one of nickel-chromium molybdenum steel, maraging steel, and precipitation hardening stainless steel, the mechanical strength of the outer teeth is made excellent, and the lubricant is used as the outer teeth. It can be held more effectively on the top.

In the robot of the present invention, the gear device is
The internal gear having the internal teeth and
A flexible external gear having the external teeth that partially meshes with the internal teeth,
It is preferable to have a wave generator that bends the external gear to move the meshing position between the internal gear and the external gear in the circumferential direction.

In such a gear device, the internal gear and the external gear generally mesh with each other with extremely few backlashes, so that the requirement for the lubrication life of the lubricant is extremely high. Therefore, when the present invention is applied to such a gear device, the effect becomes remarkable.

The gear device of the present invention includes internal and external teeth that mesh with each other.
With a lubricant disposed between the internal teeth and the external teeth,
The average crystal grain size of the constituent material of the outer tooth is smaller than the average crystal grain size of the constituent material of the inner tooth.
According to such a gear device, the lubrication life of the lubricant can be effectively improved.

It is a figure which shows the schematic structure of the embodiment of the robot of this invention. It is an exploded perspective view which shows the gear device which concerns on 1st Embodiment of this invention. It is a vertical sectional view of the gear device shown in FIG. It is a front view of the gear device shown in FIG. It is a figure explaining the lubricant arranged in the meshing part and the sliding part of the gear device shown in FIG. It is a vertical sectional view which shows the gear device which concerns on 2nd Embodiment of this invention. It is an exploded perspective view which shows the gear device which concerns on 3rd Embodiment of this invention. It is a vertical sectional view of the gear device shown in FIG. 7.

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

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

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the robot of the present invention.
The robot 100 shown in FIG. 1 can perform operations such as supplying, removing, transporting, and assembling precision equipment and parts (objects) constituting the precision equipment.

The robot 100 is a 6-axis vertical articulated robot, and includes a base 111, a robot arm 120 connected to the base 111, a force detector 140 and a hand 130 provided at the tip of the robot arm 120, and a hand 130. Has. Further, the robot 100 has a control device 110 that controls a plurality of drive sources (including a motor 150 and a gear device 1) that generate power to drive the robot arm 120.

The base 111 is a portion for attaching the robot 100 to an arbitrary installation location. The location where the base 111 is installed is not particularly limited, and examples thereof include a floor, a wall, a ceiling, and a movable carriage.

The robot arm 120 includes a first arm 121 (arm), a second arm 122 (arm), a third arm 123 (arm), a fourth arm 124 (arm), a fifth arm 125 (arm), and the like. It has a sixth arm 126 (arm), and these are connected in this order from the base end side (base side) toward the tip end side. The first arm 121 is connected to the base 111. For example, a hand 130 (end effector) for gripping various parts and the like is detachably attached to the tip of the sixth arm 126. This hand 130 has two fingers 131 and 132, and for example, various parts and the like can be gripped by the fingers 131 and 132.

The base 111 is provided with a drive source having a motor 150 such as a servomotor for driving the first arm 121 and a gear device 1 (reducer). Further, although not shown, each arm 121 to 126 is also provided with a plurality of drive sources having a motor and a speed reducer, respectively. Then, each drive source is controlled by the control device 110.

In such a robot 100, the gear device 1 transmits a driving force from one of the base 111 (first member) and the first arm 121 (second member) to the other. More specifically, the gear device 1 transmits a driving force for rotating the first arm 121 with respect to the base 111 from the base 111 side to the first arm 121 side. Here, the gear device 1 functions as a speed reducer, so that the rotation of the driving force can be reduced and the first arm 121 can be rotated with respect to the base 111. In addition, "rotation" includes moving in both directions including one direction or the opposite direction with respect to a certain center point, and rotating with respect to a certain center point.

As described above, the robot 100 includes the base 111 which is the "first member", the first arm 121 which is the "second member" rotatably provided with respect to the base 111, and the base 111 ( The first member) and the gear device 1 that transmits a driving force from one side of the first arm 121 (second member) to the other side are provided. An arbitrary number of arms sequentially selected from the first arm 121 side among the second to sixth arms 122 to 126 may be regarded as the "second member". That is, it can be said that a structure composed of an arbitrary number of arms sequentially selected from the first arm 121 side among the first arm 121 and the second to sixth arms 122 to 126 is the "second member". For example, it can be said that the structure composed of the first and second arms 121 and 122 is the "second member", and the entire robot arm 120 can be said to be the "second member". Further, the "second member" may include the hand 130. That is, it can be said that the structure including the robot arm 120 and the hand 130 is the "second member".

By providing the gear device 1 as described below, the robot 100 as described above can effectively improve the lubrication life of the lubricant used in the gear device 1.

2. Gear device Hereinafter, embodiments of the gear device of the present invention will be described.

<First Embodiment>
FIG. 2 is an exploded perspective view showing a gear device according to the first embodiment of the present invention. FIG. 3 is a vertical cross-sectional view of the gear device shown in FIG. FIG. 4 is a front view of the gear device shown in FIG. In each drawing, for convenience of explanation, the dimensions of each part are exaggerated as necessary, and the dimensional ratio between the parts does not always match the actual dimensional ratio.

The gear device 1 shown in FIGS. 2 to 4 is a strain wave gearing device, and is used as, for example, a speed reducer. The gear device 1 is arranged inside a rigid gear 2 which is an internal gear, a flexible gear 3 which is a cup-shaped external gear arranged inside the rigid gear 2, and a flexible gear 3. It has a wave generator 4 and the like.

In this gear device 1, the cross section of the flexible gear 3 has a portion deformed into an ellipse or an oval shape by the wave generator 4, and the flexible gear 3 is rigid at both ends on the long axis side of the portion. It meshes with the gear 2. The number of teeth of the rigid gear 2 and the flexible gear 3 are different from each other.

In the present embodiment, the rigid gear 2 is fixed to the base 111 (first member) side of the robot 100 described above, and the flexible gear 3 is connected to the first arm 121 (second member) side of the robot 100 described above. The wave generator 4 is connected to the rotation shaft side of the motor 150 of the robot 100 described above.

In such a gear device 1, for example, when a driving force (for example, a driving force from the motor 150 described above) is input to the wave generator 4, the rigid gear 2 and the flexible gear 3 are in meshing positions with each other. Rotates relatively around the axis a due to the difference in the number of teeth while moving in the circumferential direction. As a result, the rotation due to the driving force (rotational force) input from the driving source to the wave generator 4 can be decelerated and output from the flexible gear 3. That is, it is possible to realize a speed reducer in which the wave generator 4 is on the input shaft side and the flexible gear 3 is on the output shaft side.

The connection form of the rigid gear 2, the flexible gear 3, and the wave generator 4 is not limited to the above-mentioned form. For example, the flexible gear 3 is fixed to the base 111 side, and the rigid gear 2 is connected to the first. The gear device 1 can be used as a speed reducer even if it is connected to the arm 121 side. Further, even if the flexible gear 3 is connected to the rotating shaft side of the motor 150, the gear device 1 can be used as a speed reducer. In this case, the wave generator 4 is fixed to the base 111 side and the rigid gear 2 may be connected to the first arm 121 side. Further, when the gear device 1 is used as a speed increaser (when the rotation of the input driving force is accelerated), the relationship between the input side (motor 150 side) and the output side (first arm 121 side) described above is established. You can do the opposite.

Hereinafter, the configuration of the gear device 1 will be briefly described.
As shown in FIGS. 2 to 4, the rigid gear 2 is a gear made 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 tooth 23 has a tooth streak parallel to the axis a.

The flexible gear 3 is inserted inside the rigid gear 2. The flexible gear 3 is a gear having flexibility that can be flexed and deformed in the radial direction, and is an external gear having 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. By having the flexible gear 3 and the rigid gear 2 having different numbers of teeth in this way, a speed reducer can be realized.

In the present embodiment, the flexible gear 3 has a cup shape with one end open, and external teeth 33 are formed at the end on the open side. Here, the flexible gear 3 is connected to a tubular (more specifically, cylindrical) body 31 (cylinder) around the axis a and one end side of the body 31 in the axis a direction. It has a bottom portion 32 and a cylinder. As a result, the end portion of the body portion 31 opposite to the bottom portion 32 can be easily bent in the radial direction. Therefore, good flexion meshing of the flexible gear 3 with respect to the rigid gear 2 can be realized. Further, the rigidity of the end portion of the body portion 31 on the bottom portion 32 side can be increased. Therefore, the input shaft or the output shaft can be stably connected to the bottom portion 32.

Further, as shown in FIG. 3, the bottom portion 32 is formed with a hole 321 penetrating along the axis a and a plurality of holes 322 penetrating around the hole 321. A shaft body on the output side can be inserted through the hole 321. Further, the hole 322 can be used as a screw hole through which a screw for fixing the shaft body on the output side to the bottom portion 32 is inserted. It should be noted that these holes may be provided as appropriate and may be omitted.

As shown in FIG. 3, the wave generator 4 is arranged inside the flexible gear 3 and is rotatable around the axis a. Then, the wave generator 4 deforms the cross section of the portion of the flexible gear 3 opposite to the bottom 32 into an elliptical shape or an oval shape having a long axis La and a short axis Lb, and makes the external teeth 33 a rigid gear. It meshes with the internal tooth 23 of 2 (see FIG. 4). Here, the flexible gear 3 and the rigid gear 2 are rotatably meshed with each other inside and outside the same axis a.

In the present embodiment, the wave generator 4 can rotate around the main body 41, the shaft 42 protruding from the main body 41 along the axis a, and the axis a1 parallel to the axis a with respect to the main body 41. It has a pair of rollers 43 provided. In such a wave generator 4, a pair of rollers 43 rolls on the inner peripheral surface of the flexible gear 3 to push the flexible gear 3 from the inside, thereby expanding the main body 41, the shaft 42, and the flexible gear 3. A pair of rollers 43 can rotate around the axis a. Therefore, for example, when a driving force is input to the wave generator 4 from the driving source, the meshing positions of the rigid gear 2 and the flexible gear 3 move in the circumferential direction.

The configuration of the gear device 1 has been briefly described above. In such a gear device 1, for example, when a driving force (for example, a driving force from the motor 150 described above) is input to the wave generator 4, the rigid gear 2 and the flexible gear 3 are subjected to, as described above. , While the meshing positions of each other move in the circumferential direction, they rotate relatively around the axis a due to the difference in the number of teeth. Here, a lubricant is used to reduce the friction of each part of the gear device 1, but in the gear device 1, the lubricant is kept in a good state for a long period of time at the meshing portion between the rigid gear 2 and the flexible gear 3. It has the structure described below in order to hold it over.

FIG. 5 is a diagram illustrating a lubricant arranged in a meshing portion and a sliding portion of the gear device shown in FIG.

As described above, the gear device 1 may be a rigid gear 2 which is an "internal gear" having internal teeth 23 and a flexible "external gear" having external teeth 33 which partially mesh with the internal teeth 23. It has a flexible gear 3 and a wave generator 4 that bends the flexible gear 3 to move the meshing position of the rigid gear 2 and the flexible gear 3 in the circumferential direction. Here, as shown in FIG. 5, a lubricant is applied to the meshing portion 61, which is a region between the tooth surface 231 of the internal tooth 23 of the rigid gear 2 and the tooth surface 331 of the external tooth 33 of the flexible gear 3. 51 is arranged. That is, the gear device 1 is provided in the middle of the transmission path of the driving force (for example, the driving force from the motor 150), and is arranged between the internal teeth 23 and the external teeth 33 and the internal teeth 23 and the external teeth 33 that mesh with each other. It has a lubricant 51 which is used. Here, "in the middle of the driving force transmission path" means an arbitrary position from the start point to the end point of the driving force transmission path.

The inner teeth 23 and the outer teeth 33 are each made of a metal material as described later, and have crystal grains in the metal structure thereof. The average crystal grain size of the constituent material of the outer tooth 33 is smaller than the average crystal grain size of the constituent material of the inner tooth 23.

Due to the magnitude relationship of the average crystal grain size of the constituent materials of the internal tooth 23 and the external tooth 33, the crystal grain size of the external tooth 33 can be reduced to facilitate holding of the lubricant 51 on the external tooth 33. it can. Therefore, the lubricant 51 can be kept on the outer teeth 33 against the centrifugal force due to the rotation of the outer teeth 33. Here, the lubricant 51 is preferentially held at the grain boundaries existing on the surface of the outer teeth 33. It is considered that this is because the grain boundaries play a role like fine recesses and grooves accommodating the lubricant 51. Therefore, by reducing the crystal grain size of the outer teeth 33, the density of the crystal grain boundaries existing on the surface of the outer teeth 33 becomes higher, and accordingly, the lubricant 51 is more likely to be held on the surface of the outer teeth 33. ..

Further, by reducing the crystal grain size of the outer teeth 33, the mechanical strength of the outer teeth 33 can be increased and the toughness of the outer teeth 33 can be increased. As described above, the external teeth 33 are repeatedly deformed as the rigid gears 2 and the flexible gears 3 move their meshing positions with each other, so that higher mechanical strength and toughness are required than those of the internal teeth 23. .. Therefore, it is extremely beneficial to increase the mechanical strength and toughness of the external teeth 33. In general, the mechanical strength of a metal increases in inverse proportion to the 1/2 power of the crystal grain size.

On the other hand, the crystal grain size of the internal teeth 23 can be increased to facilitate the flow of the lubricant 51 along the internal teeth 23. Therefore, it is possible to reduce that the lubricant 51 is biased or solidified on the internal teeth 23. Here, since the internal teeth 23 are non-rotating, the centrifugal force unlike the external teeth 33 described above does not act on the internal teeth 23, so that the lubricant 51 tends to be easily held from the beginning. Therefore, by making the lubricant 51 on the internal teeth 23 flow easily, it is possible to prevent the lubricant 51 from sticking and running out of oil at a necessary place. As a result, the performance of the lubricant 51 can be fully exhibited.

As described above, in the gear device 1, the effect of retaining the lubricant 51 on the outer teeth 33 and the effect of reducing the lubricant 51 from being biased or solidified on the inner teeth 23 as described above. The two effects of can be exerted at the same time. Then, these two effects can be synergistically improved to effectively improve the lubrication life of the lubricant 51. In particular, in a strain wave gearing device such as the gear device 1, since the internal gear and the external gear generally mesh with each other with extremely few backlashes, the requirement for the lubrication life of the lubricant is extremely high. Therefore, when the present invention is applied to such a gear device, the effect becomes remarkable.

Although detailed description will be omitted, the sliding portion 62, which is a region between the inner peripheral surface 311 of the body portion 31 of the flexible gear 3 and the outer peripheral surface 431 of the roller 43 of the wave generator 4, is provided on the sliding portion 62. The lubricant 52 is arranged. Further, although not shown, a lubricant is also arranged on the sliding portion in the wave generator 4.

Here, the "average crystal grain size" is measured in accordance with JIS G 0551 "Steel-Crystal Grain Size Microscopic Test Method". The average crystal grain size is measured by etching the surface of the test piece (inner tooth or outer tooth) with a corrosive solution to make grain boundaries appear, and observing the appearing grain boundaries under a microscope. As the corrosive liquid, 5% nital (5% nitrate-ethyl alcohol) is used. Further, the magnitude relationship of the average crystal grain size as described above may be satisfied at least in the internal teeth 23 and the external teeth 33, and may not be satisfied in the other parts of the rigid gear 2 and the flexible gear 3. It is good, but if the other parts are also satisfied, the effect becomes remarkable. Further, the crystal grain sizes of the internal teeth 23 and the external teeth 33 can be adjusted according to, for example, the material (metal composition) constituting them and the heat treatment at the time of production.

When the average crystal grain size of the constituent material of the outer tooth 33 is A and the average crystal grain size of the constituent material of the inner tooth 23 is B, the relationship A <B may be satisfied. Is preferably 1.2 ≦ B / A ≦ 100, and more preferably 2 ≦ B / A ≦ 50. On the other hand, if the B / A is too small, the balance between the two effects described above tends to be poor, while if the B / A is too large, the strength difference between the internal teeth 23 and the external teeth 33 becomes too large. Therefore, one of the internal teeth 23 and the external teeth 33 tends to wear faster.

The average crystal grain size (B) of the constituent material of the internal tooth 23 is not particularly limited, but is preferably in the range of 20 μm or more and 150 μm or less, more preferably in the range of 30 μm or more and 100 μm or less, and more preferably 30 μm or more. It is more preferably within the range of 50 μm or less. This allows the lubricant 51 to flow more effectively along the internal teeth 23. Further, when the internal teeth 23 are made of metal, the mechanical strength of the internal teeth 23 can be made excellent. On the other hand, if the average crystal grain size is too small, the fluidity of the lubricant 51 on the internal teeth 23 tends to decrease. On the other hand, if the average crystal grain size is too large, the strength of the internal teeth 23 may be insufficient depending on the constituent materials of the internal teeth 23. If the entire rigid gear 2 satisfies the above-mentioned range of the average crystal grain size, the above-mentioned effect becomes remarkable.

On the other hand, the average crystal grain size (A) of the constituent material of the external tooth 33 is not particularly limited as long as the above-mentioned A <B is satisfied, but is preferably in the range of 0.5 μm or more and 30 μm or less, and 5 μm or more and 20 μm or less. It is more preferable that it is within the range of 5 μm or more and 15 μm or less. As a result, the lubricant 51 can be more effectively held on the outer teeth 33. Further, when the outer teeth 33 are made of metal, the mechanical strength of the outer teeth 33 can be made excellent. On the other hand, if the average crystal grain size is too small, the processability when manufacturing the outer tooth 33 is poor, and the depth of the recess due to the crystal grain boundary existing on the surface of the outer tooth 33 is also reduced. On the contrary, it becomes difficult to hold the lubricant 51 on the external teeth 33. On the other hand, if the average crystal grain size is too large, the effect of holding the lubricant 51 on the external teeth 33 tends to decrease, and it is difficult to secure the mechanical strength and toughness required for the external teeth 33. .. If the entire flexible gear 3 satisfies the above-mentioned range of the average crystal grain size, the above-mentioned effect becomes remarkable.

Here, it is preferable that the internal teeth 23 and the external teeth 33 are each made of a metal material, and in particular, since they are excellent in mechanical properties and workability and are relatively inexpensive, an iron-based material is used. It is preferable to use it. In general, metals have excellent mechanical properties, can be machined relatively easily, and have high processing accuracy. Therefore, the internal teeth 23 and the external teeth 33 having excellent characteristics (mechanical strength, accuracy, etc.) can be easily realized. In particular, since the external tooth 33 preferably has high toughness as described above, it is preferably made of a metal material. Since the internal tooth 23 is a substantially rigid body, it can be made of a ceramic material, but it is preferable to use a metal material from the viewpoint of the balance of strength with the external tooth 33.

The metal material constituting the internal teeth 23 is not particularly limited as long as the above-mentioned A <B is satisfied, and various metal materials can be used. In particular, any one of cast iron and precipitation hardening stainless steel can be used. On the other hand, it is preferable. Since the internal tooth 23 is composed of either cast iron or precipitation hardening stainless steel, the internal tooth 23 having excellent characteristics (mechanical strength, accuracy, etc.) can be easily realized. In particular, cast iron and precipitation hardening stainless steel, respectively, are likely to achieve appropriate grain sizes that effectively allow the lubricant 51 to flow along the internal teeth 23 as described above, as well as mechanical strength and processing. Excellent sexual balance. Therefore, by forming the internal teeth 23 with either cast iron or precipitation hardening stainless steel, the mechanical strength of the internal teeth 23 is made excellent, and the lubricant 51 is applied along the internal teeth 23. It can be fluidized more effectively. It is sufficient that at least the surface of the internal teeth 23 of the rigid gear 2 is made of the above-mentioned material, but in order to make the above-mentioned effect remarkable, the tooth bottom is made of the above-mentioned material. It is preferable to configure it. Further, if the entire rigid gear 2 is made of the material as described above, the production becomes relatively easy while obtaining the same effect. Further, the internal teeth 23 may be made of a material obtained by adding another substance to either one of cast iron and precipitation hardening stainless steel.

The metal material constituting the external tooth 33 is not particularly limited as long as the above-mentioned A <B is satisfied, and various metal materials can be used. In particular, nickel chrome molybdenum steel, maraging steel and precipitation hardening type steel can be used. It is preferably any one of stainless steels. Since the outer teeth 33 are made of any one of nickel chrome molybdenum steel, maraging steel and precipitation hardening stainless steel, the outer teeth 33 having excellent characteristics (mechanical strength, accuracy, etc.) can be obtained. It can be easily realized. In particular, nickel-chromium molybdenum steel, maraging steel, and precipitation hardening stainless steel, respectively, can easily realize an appropriate crystal grain size that effectively holds the lubricant 51 on the outer teeth 33 as described above, and also Excellent balance between mechanical strength and workability. Therefore, by forming the outer teeth 33 with any one of nickel-chromium molybdenum steel, maraging steel, and precipitation hardening stainless steel, the mechanical strength of the outer teeth 33 is made excellent, and the lubricant 51 is used. Can be more effectively held on the external teeth 33. The surface of the outer teeth 33 of the flexible gear 3 may be made of the material as described above, but in order to make the effect as described above remarkable, the tooth bottom is made of the material as described above. It is preferable to configure it. Further, if the entire flexible gear 3 is made of the material as described above, the production becomes relatively easy while obtaining the same effect. Further, the outer teeth 33 may be made of a material obtained by adding another substance to any one of nickel-chromium molybdenum steel, maraging steel and precipitation hardening stainless steel.

The lubricant 51 may be grease or lubricating oil, but is preferably grease. That is, the lubricant 51 preferably contains a base oil and a thickener. As a result, the lubricant 51 can be made into a solid or semi-solid grease. Therefore, it is possible to make it easier for the lubricant 51 to stay in the required place. Here, as the thickener, for example, soap-based soaps such as calcium soap, calcium composite soap, sodium soap, aluminum soap, lithium soap, lithium composite soap, polyurea, sodium terephthalate, and polytetrafluoroethylene (PTFE). ), Non-soap type such as organic bentonite and silica gel, and one of them can be used alone or in combination of two or more, but lithium soap is preferably used. By using lithium soap as the thickener, the shear stability of the lubricant 51 can be made excellent. Further, the balance of the characteristics of the lubricant 51 as a lubricant can be made excellent.

Examples of the base oil include mineral oils such as paraffin-based and naphthen-based oils (refined mineral oils), synthetic oils such as polyolefins, esters, and silicones, and one of these may be used alone or in combination of two or more. Can be used in combination.

When the lubricant 51 contains a base oil and a thickener, the lubricant 51 includes additives such as an antioxidant, an extreme pressure agent, and a rust preventive, as well as graphite, molybdenum sulfide, and polytetrafluoroethylene (PTFE). ) And the like, preferably containing a solid lubricant or the like. As a result, the lubricant 51 capable of exhibiting a high maximum non-seizure load and fusion load over a long period of time can be easily obtained.

In particular, it is preferable that the lubricant 51 contains an extreme pressure agent. As a result, seizure and scuffing can be effectively prevented even when the lubricated portion is in an extreme pressure lubrication state. In particular, it is preferable to use an organic molybdenum compound or zinc dialkyldithiophosphate as the extreme pressure agent.

Since the lubricant 51 contains an organic molybdenum compound, friction in the lubricated portion can be effectively reduced. In particular, organic molybdenum exhibits extreme pressure resistance and abrasion resistance equivalent to molybdenum disulfide, and is superior in oxidative stability to molybdenum disulfide. Therefore, the life of the lubricant 51 can be extended. Here, the content of the organic molybdenum compound in the lubricant 51 is preferably in the range of, for example, 1% by mass or more and 5% by mass or less. The content of zinc dialkyldithiophosphate in the lubricant 51 is preferably in the range of, for example, 1% by mass or more and 5% by mass or less.

<Second Embodiment>
Next, the second embodiment of the present invention will be described.
FIG. 6 is a vertical sectional view showing a gear device according to a second embodiment of the present invention.

In the following description, the present embodiment will be mainly described with respect to the differences from the above-described embodiment, and the description of the same matters will be omitted.

The gear device 1A shown in FIG. 6 has a flexible gear 3A which is a hat-type external gear arranged inside the rigid gear 2.

The flexible gear 3A has a flange portion 32A provided on one end side of a body portion 31 having a tubular shape around the axis a in the direction of the axis a so as to project on the side opposite to the axis a. Even with the flexible gear 3A having such a shape, it is possible to realize good flexion meshing of the flexible gear 3A with respect to the rigid gear 2. Further, the input shaft or the output shaft can be stably connected to the flange portion 32A.

In the present embodiment, the flange portion 32A is formed with a plurality of holes 322A penetrating along the axis a. The hole 322A can be used as a screw hole through which a screw for fixing the shaft body on the output side to the flange portion 32A is inserted. Further, a shaft body on the output side can be inserted through the inner peripheral portion 321A of the flange portion 32A.

As described above, the gear device 1A is a flexible "external gear" having a rigid gear 2 which is an "internal gear" having internal teeth 23 and an external gear 33 which is a flexible "external gear" which partially meshes with the internal teeth 23. It has a sex gear 3A and a wave generator 4 that bends the flexible gear 3A to move the meshing position of the rigid gear 2 and the flexible gear 3A in the circumferential direction. Here, the gear device 1A has internal teeth 23 and external teeth 33 that mesh with each other, and a lubricant 51 that is arranged between the internal teeth 23 and the external teeth 33. Then, as in the first embodiment described above, the average crystal grain size of the constituent material of the outer tooth 33 is smaller than the average crystal grain size of the constituent material of the inner tooth 23.

The lubrication life of the lubricant 51 can also be effectively improved by the second embodiment as described above.

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

FIG. 7 is an exploded perspective view showing a gear device according to a third embodiment of the present invention. FIG. 8 is a vertical cross-sectional view of the gear device shown in FIG. 7.

In the following description, the present embodiment will be mainly described with respect to the differences from the above-described embodiment, and the description of the same matters will be omitted.

The gear device 200 shown in FIGS. 7 and 8 includes a main body portion 202 having a columnar outer shape. A first rotating shaft 203 is provided on one side of the main body 202 in the axial direction, while a second rotating shaft 204 is provided on the other side of the main body 202 in the axial direction. The first rotation shaft 203 and the second rotation shaft 204 rotate about the same central shaft 205 as each other. 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 described later and output from the second rotating shaft 204. That is, the first rotation shaft 203 is an input shaft that rotates at high speed, and the second rotation shaft 204 is an output shaft that rotates at low speed.

As shown in FIG. 7, the gear device 200 includes a cylindrical ring gear 206 having a cavity 206c. A plurality of gear teeth 206a are formed on the inner circumference of the ring gear 206. Further, inside the ring gear 206, a first revolution gear 207 and a second revolution gear 208 having an outer circumference slightly smaller than the inner circumference of the ring gear 206 are installed. A plurality of gear teeth 207a having a number smaller than the number of teeth of the gear teeth 206a are arranged on the outer periphery of the first revolution gear 207, and the same number as the number of teeth of the gear teeth 207a is arranged on the outer circumference of the second revolution gear 208. A plurality of gear teeth 208a are arranged. Then, the gear teeth 207a and the gear teeth 208a are in mesh with the gear teeth 206a.

A shaft hole 207b is provided in the center of the first revolution gear 207, and similarly, a shaft hole 208b is provided in 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 to the central shaft 205 by the same amount on opposite sides. Then, 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 central axis 205 is located between the portion where the gear tooth 207a meshes with the gear tooth 206a and the portion where the gear tooth 208a meshes with the gear tooth 206a.

The first revolution gear 207 is provided with first through holes 207c at four locations on a concentric circle centered on the center of the first revolution gear 207. Similarly, the second revolution gear 208 is provided with second through holes 208c at four locations on a concentric circle centered on the center of the second revolution gear 208. Through holes 213 for taking out the rotation movement of the first revolution gear 207 are inserted into each of the first through holes 207c and each second through hole 208c, respectively. 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 through pin 213 penetrates the inside of the first elastic portion 214 and the second elastic portion 215.

Each through 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 the nut 217 on the second rotating shaft 204 side. It is fixed. The lower lid plate 216 and the upper lid plate 218 are aligned 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 central hole 216a into which the first rotation shaft 203 is inserted is formed in the center of the lower lid plate 216. Then, one end of the first rotating shaft 203 on the first eccentric cam 211 and the second eccentric cam 212 side protrudes from the lower lid plate 216 into the main body 202, and the other end of the first rotating shaft 203 is the lower lid plate 216. It protrudes from the main body 202 to the outside. The second rotating shaft 204 is fixed to the center of the upper lid plate 218. Then, as the upper lid plate 218 rotates, the rotational torque of the upper lid plate 218 is transmitted to the second rotation shaft 204.

In the gear device 200 configured as described above, the meshing portion between the ring gear 206, which is the “internal gear”, and the first revolution gear 207 and the second revolution gear 208, which are the “external gears”, is not shown, but is not shown. A lubricant similar to the lubricant 51 of the first embodiment described above is arranged. The average crystal grain size of the constituent materials of the outer teeth of the first revolution gear 207 and the second revolution gear 208 is smaller than the average crystal grain size of the constituent materials of the internal teeth of the ring gear 206.

The lubrication life of the lubricant can also be effectively improved by the third embodiment as described above.

The robot and the gear device of the present invention have been described above based on the illustrated embodiment, but the present invention is not limited to this, and the configuration of each part is an arbitrary configuration having the same function. Can be replaced with. Further, any other constituents may be added to the present invention. Moreover, each embodiment may be combined appropriately.

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

Further, in the above-described embodiment, the 6-axis vertical articulated robot has been described, but the present invention is not limited to this as long as it uses a gear device having a flexible gear, for example, a robot joint. The number is arbitrary, and it can also be applied to a horizontal articulated robot (SCARA robot).

Further, the present invention can be applied to various gear devices having internal teeth and external teeth that mesh with each other, and the configuration of the gear device is not limited to the above-described embodiment. For example, the wave generator may have a ball bearing in which the outer peripheral surface of the inner ring has an elliptical shape and the outer ring has an elastically deformed thin wall.

Hereinafter, specific examples of the present invention will be described.
1. 1. Manufacture of gear device (reducer) (Example 1)
A gear device having a configuration as shown in FIG. 2 was manufactured.

Here, the manufactured gear device had an outer diameter of the internal gear of φ60, an inner diameter of the internal gear and an outer diameter of the external gear (meshing reference circle diameter) of φ45, and a reduction ratio of 50. Cast iron was used as the constituent material of the internal gear, and nickel-chromium molybdenum steel was used as the constituent material of the external gear. The average crystal grain size (B) of the constituent material of the internal teeth of the internal gear was 20 μm, and the average crystal grain size (A) of the constituent material of the external teeth of the external gear was 0.5 μm.

(Examples 2 to 13, comparative example)
A gear device was manufactured in the same manner as in Example 1 described above, except that the constituent materials and the average crystal grain size of the internal gear and the external gear were shown in Table 1.

In Table 1, SNCM439 is nickel-chromium molybdenum steel, SUS630 is precipitation hardening stainless steel, and cast iron is ductile cast iron.

2. Evaluation The above-mentioned 1. For each gear device obtained in the above, continuous operation was performed at an input shaft rotation speed of 2000 rpm and a load torque of 1000 Nm, and the service life (total input shaft rotation speed with a 50% failure probability) was measured. The results are also shown in Table 1.

As is clear from Table 1, each of the examples has a significantly longer life than the comparative example.

1 ... Gear device, 1A ... Gear device, 2 ... Rigid gear (internal gear), 3 ... Flexible gear (external gear), 3A ... Flexible gear (external gear), 4 ... Wave generator, 23 ... Internal Gears, 31 ... Body, 32 ... Bottom, 32A ... Flange, 33 ... External teeth, 41 ... Main body, 42 ... Shaft, 43 ... Roller, 51 ... Lubricant, 52 ... Lubricant, 61 ... Mesh, 62 ... Sliding part, 100 ... Robot, 110 ... Control device, 111 ... Base (first member), 120 ... Robot arm, 121 ... First arm (second member), 122 ... Second arm, 123 ... First 3 arm, 124 ... 4th arm, 125 ... 5th arm, 126 ... 6th arm, 130 ... hand, 131 ... finger, 132 ... finger, 140 ... force detector, 150 ... motor, 200 ... gear device, 202 ... Main body, 203 ... 1st rotation shaft, 204 ... 2nd rotation shaft, 205 ... Central shaft, 206 ... Ring gear, 206a ... Gear teeth, 206c ... Cavity, 207 ... First revolution gear, 207a ... Gear teeth, 207b ... Shaft hole, 207c ... 1st through hole, 208 ... 2nd revolving gear, 208a ... Gear tooth, 208b ... Shaft hole, 208c ... 2nd through hole, 209 ... 1st bearing, 210 ... 2nd bearing, 211 ... 1 eccentric cam, 212 ... 2nd eccentric cam, 213 ... through pin, 214 ... first elastic part, 215 ... second elastic part, 216 ... lower lid plate, 216a ... center hole, 217 ... nut, 218 ... upper lid plate , 231 ... Tooth surface, 311 ... Inner peripheral surface, 321 ... Hole, 321A ... Inner peripheral part, 322 ... Hole, 322A ... Hole, 331 ... Tooth surface, 431 ... Outer surface, La ... Long axis, Lb ... Short axis, a ... Axis, a1 ... Axis

Claims (8)

The first member and
A second member rotatably provided with respect to the first member,
A gear device that transmits a driving force from one side of the first member and the second member to the other side.
With
The gear device
Internal and external teeth that are provided in the middle of the driving force transmission path and mesh with each other,
With a lubricant disposed between the internal teeth and the external teeth,
A robot characterized in that the average crystal grain size of the constituent material of the outer tooth is smaller than the average crystal grain size of the constituent material of the inner tooth. Robot according to claim 1, wherein an average crystal grain size of the material of the inner teeth is 20μm or more 150μm or less. The robot of claim 1 or 2, the average crystal grain size of the material of the outer teeth is 0.5μm or more 30μm or less. The robot according to any one of claims 1 to 3, wherein the internal teeth and the external teeth are each made of a metal material. The robot according to any one of claims 1 to 4, wherein the internal teeth are made of either cast iron or precipitation hardening stainless steel. The robot according to any one of claims 1 to 5, wherein the external teeth are made of any one of nickel-chromium molybdenum steel, maraging steel, and precipitation hardening stainless steel. The gear device
The internal gear having the internal teeth and
A flexible external gear having the external teeth that partially meshes with the internal teeth,
The robot according to any one of claims 1 to 6, further comprising a wave generator that bends the external gear to move the meshing position between the internal gear and the external gear in the circumferential direction. With internal and external teeth that mesh with each other,
With a lubricant disposed between the internal teeth and the external teeth,
A gear device characterized in that the average crystal grain size of the constituent material of the outer tooth is smaller than the average crystal grain size of the constituent material of the internal tooth.

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