JPS6229194B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a joint structure used in a robot or machine tool, etc., having an arm and/or wrist with multiple degrees of freedom, and specifically relates to a joint structure used in a robot or machine tool having an arm and/or wrist having multiple degrees of freedom. Regarding the structure of

Various types of articulated robots have been developed, but all of them have joints made up of a combination of gears and links, and their drive source uses a pneumatic hydraulic or electric motor with a single output shaft. Normally, power is transmitted to other members within the joint via a gear train, resulting in the overall size of the device and the problem of lack of smooth operation.

The applicant of the present invention previously disclosed a modular articulated robot shown in Japanese Patent Application Laid-Open No. 59-205292. According to this articulated robot, at least one modular articulated robot unit has a drive unit and an articulated unit in which the respective output shafts of motors having a plurality of rotors arranged concentrically protrude from each other in a telescoping manner. The joint unit includes a first housing having a hollow spherical part at one end of a cylindrical part having at least two nuts attached thereto, and a second housing, the spherical part being in spherical contact with the first housing and the second housing. screws screwed into the nuts of the cylindrical portion and a central rotating shaft that is coupled to be relatively rotatable by rotating the central rotating shaft and that is supported in the first housing and the second housing so as not to be able to move in the axial direction; a screw-type telescopic shaft, and the corresponding axes of the central rotating shaft and the screw-type telescopic shaft are each connected by a constant velocity joint on a plane including the center point of the spherical part,
The modular articulated robot unit is configured such that an operating member slidably inserted into the cylindrical portion of the one housing is engaged with a central rotating shaft provided in the housing, and the output shaft of the drive unit is It is connected to the central rotating shaft of the housing and the threaded telescoping shaft to transmit rotation. With this configuration, each part of the robot can be divided into drive units, arm units, or wrist units, and multiple units can be freely added as needed, increasing the overall degree of freedom of the robot. It is functional and can be put together compactly as a whole. However, as mentioned above, in this multi-jointed robot, the pair of central rotating shafts and telescopic shafts are connected by a constant velocity joint, so it is necessary to manufacture the constant velocity joints, gears, etc. with high precision, resulting in high production costs. It tends to be higher. In addition, in this modular articulated robot, one drive unit connects the screw shaft to the other screw shaft through the constant velocity joint, that is, the drive unit housed in the first housing connects the screw shaft to the screw shaft in the second housing. It conveys rotation,
Errors inevitably accumulate due to the mechanism, and there were some difficulties in achieving highly accurate operation. Furthermore, the first
The second housing is fitted with spherical contact and has a structure that cannot support forces in the torsional direction, resulting in a drawback that the rigidity against torsion as a robot unit is low.

The present invention eliminates the drawbacks of the above-mentioned modular type jointed robot, increases the torsional rigidity of the joint part and improves flexibility, the joint itself forms an independent unit, and the overall degree of freedom is high. Moreover, it is an object of the present invention to provide a joint structure that does not cause cumulative errors even when a plurality of joints are connected, has an extremely smooth and precise operation, has a compact overall shape, and is easy to manufacture.

For this purpose, the joint structure of the present invention includes a cylindrical first housing and a second housing, a nut rotatably supported in the first and second housings, and a screw threaded into the nut. a slide shaft having a mated threaded portion at one end and a shaft portion at the other end that projects in the axial direction from the end of the housing and is supported by the housing in a non-rotatable and axially movable manner; The slide shafts are arranged parallel to each other and each housing has four threaded linear slide mechanisms arranged in each housing, and the threaded linear slide mechanisms of each housing are arranged in parallel with each other with respect to the central axis of the articulated arm. The two bodies are arranged so as to face each other in different directions, and further include opposing shaft portions of a slide shaft protruding from the first housing and a slide shaft opposing the slide shaft protruding from the second housing. a connecting means that connects each of the housings in a flexible manner by spherical fitting, a drive unit fixed to the first and second housings, respectively, and an output transmission means that transmits the rotation of the output shaft of the drive unit to the nut. , a bellows connecting opposing ends of the first and second housings in a relatively non-rotatable and bendable manner, and one of the slide shafts of the screw-type linear slide mechanism that faces the central axis of the articulated arm. is extended together with the slide shaft of the threaded linear slide mechanism connected to this by the spherical fit, and the other is contracted together with the slide shaft of the threaded linear slide mechanism connected to this by the spherical fit. It is set as follows.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a wrist joint used in robots, machine tools, etc., according to an embodiment of the present invention. In this embodiment, a wrist housing 2 is arranged at a distance in the axial direction of the housing 1 on the robot base side, and a metal bellows 3 having an accordion shape and flexible in the bending direction is arranged to close the gap between these housings. is installed. Each housing 1, 2
Two drive units 4 and 5 each having two shafts are fixed therein with their output shafts facing each other. This drive unit will be described further later, but
Each of its two output shafts 6, 7 and 8, 9 protrudes concentrically and telescopically from the motor housing 10, 11, and has gears 12, 13 at the tip of each with an axially shifted position. and 14, 15 are attached. The output shafts 6 and 7 of one drive unit rotate independently of each other. The same applies to the output shafts 8 and 9 of the other drive unit. A total of eight threaded linear slide mechanisms, four for each housing, are mounted within the housings 1 and 2. In the illustrated embodiment, four screw-type linear slide mechanisms 16 are arranged in one vertical center cross section (axial center cross section) of the joint, two each facing the other two. , 17 and 18,
19 is arranged, and four screw-type linear slide mechanisms (not shown) are arranged in the same relationship in the vertical center cross section in the direction of 90 degrees (vertical center cross section perpendicular to the paper plane of the figure). ing. However, the present invention is not necessarily limited to arranging screw-type linear slide mechanisms on vertical center cross sections that differ by 90 degrees, but as long as space permits.
4 on two vertical center cross sections with an angular relationship other than °
A total of 8 pieces may be arranged.

The screw type linear slide mechanism 16 is attached to the housing 1
A ball screw nut 22 having a driven gear 21 is rotatably supported in a cylindrical body 20 fixed to the cylindrical body 20.
Slide shaft part 2 whose front part forms a rectangular cross section
A guide member 25 having a rectangular hole formed in 4 and supporting the slide shaft portion is screwed onto the cylinder body 20. As shown in the figure, the tip of the slide shaft portion 24 of the screw type linear slide mechanism 16 is connected to the screw type linear slide mechanism 1 of the other housing 2 facing thereto.
It is connected to the tip of the slide shaft portion 26 of No. 8 in a spherical fit state. A pair of slide mechanisms 16 and 18 having such a relationship are referred to herein as axially opposed screw-type linear slide mechanisms. The other screw-type linear slide mechanisms have the same configurations as described above, and redundant explanation will be omitted. In the illustrated embodiment, the spherical centers A, B, C, and D (C and D are on the cross section perpendicular to the illustrated cross section) of the four sets of slide shafts that are spherically fitted to each other are on the same plane. Existing.

The gear 12 of one output shaft 6 of the drive unit 4 in the housing 1 is meshed with the driven gears 21 and 27 of the threaded linear slide mechanisms 16 and 17 arranged in parallel, The gear 13 of the output shaft 7 is connected to the slide mechanism 16, 17.
Screw-type linear slide mechanism (not shown) arranged in parallel on a plane (vertical center section) perpendicular to the plane containing
It meshes with a driven gear fixed to a ball screw nut. Similarly, for the drive unit 5 on the other housing 2 side, the gear 14 of one output shaft 8 meshes with the driven gears 28 and 29 of the screw type linear slide mechanisms 18 and 19 on the housing 2 side, and The gear 15 meshes with a driven gear of a ball screw nut of a screw type linear slide mechanism (not shown) in a cross section perpendicular to the illustrated cross section.

By driving the drive units 4 and 5, the slide shaft portion of the screw type linear slide mechanism is moved in the linear direction by the screw action of the mechanism. Among these eight slide shafts, the four slide shafts 24, 33, 26, and 34 that lie in the same plane are spherically fitted to each other, and 33, 34 move in opposite directions, and the slide shaft parts 24, 33 and 26, 34, which are arranged in parallel in the lateral direction with respect to the axial direction, also move in opposite directions. The relationship is set to move in the direction. The amount of movement of the slide shaft portions 24, 26 is equal, and the amount of movement of the slide shaft portions 33, 34 is also equal. The same applies to the four slide shafts of the screw type linear slide mechanism in a plan view perpendicular to this. Regarding what is shown in the cross section of FIG. 1, when the axially opposing slide shafts 24 and 26 extend toward each other, the other axially opposing slide shafts 33 and 34 extend toward each housing 1, 2, and conversely, when the slide shaft portions 24, 26 contract, the other slide shaft portions 33, 34 expand. This relationship can be obtained by setting the rotational direction of the output shafts of the drive units 4 and 5 or the screw direction of the screw type linear slide mechanism, but regardless of the rotational direction of the output shafts of the drive units, the output shafts in the same housing ( Two parallel threaded linear slide mechanisms 16 and 17 in the same plane in 1 or 2), and 18 and 19 (the same applies to those in other vertical sections)
are always set in a reverse screw relationship with each other. When the rotational directions of the output shafts of the drive units 4 and 5 on both sides are the same direction when viewed from one end of the joint, a pair of screw-type linear slide mechanisms 16, 18 and 17, 19 ( The same applies to other vertical sections), so that the opposing screws are oppositely threaded to each other. This relationship is illustrated in FIG. 2a. If the rotational direction of the output shaft is different on both sides (as viewed from one end of the joint), both sides facing in the axial direction must have a sliding mechanism with screws in the same direction. It won't happen.

With the above-mentioned combination structure of the screw-type linear slide mechanism, when the drive units 4 and 5 in each housing 1 and 2 are driven, the wrist-side housing 2 moves the mechanism part inside the housing 2 according to the rotation speed of each motor. At the same time, a swinging joint movement is performed with respect to the base housing 1 in a desired direction and at a desired angle. In this case, as mentioned above, due to the simultaneous expansion and contraction of the same amount of the spherically fitted slide shafts, the distance between the horizontally parallel slide shafts in each housing 1 and 2 is completely different. Therefore, it is possible to perform extremely smooth and precise joint movements without applying excessive force to each part of the joint internal mechanism.

FIGS. 3 and 4 are longitudinal cross-sectional views of joints according to other embodiments of the present invention, respectively. In these figures, the same parts as in FIG. 1 are given the same reference numerals, and the explanation of the parts having the same configuration will be omitted. First, in the embodiment shown in FIG. 3, a drive unit 4 housed in a housing 1 on the base side of a robot or a machine tool has three output shafts 6, 7, and 30 that are nested together. , the innermost output shaft 30 passes through the housing 1 and projects into the bellows 3. Further, an inner output shaft 8 of the drive unit 5 in the other housing 2 is formed in a hollow shape, and a rotary working shaft 31 passes through the hollow output shaft 8 and projects to both ends of the housing 2. The aforementioned third output shaft 30 of the drive unit 4 and this rotary working shaft 31 are connected within the bellows 3 via a bellows coupling ring 32. The output shaft 30 rotates independently of the other two output shafts 6, 7, and this rotation is transmitted via the bellows coupling 32 to the rotary working shaft 31, so that the rotary working shaft 31 It performs the same oscillating displacement as the side housing 2 and rotates around its axis.
A suitable work member such as a processing tool such as a drill or an end mill, a work tool such as a screwdriver, or an electrode of an electrical discharge machine (all not shown) is attached to the tip of the rotating work shaft 31, and the desired work is performed at a desired angular position. can be made to do so.

The embodiment shown in FIG. 4 is an example in which a work member of a telescoping arm is attached to form a three-degree-of-freedom joint. The configuration of the three-axis drive unit 4 and the rotary work shaft 31 in the base housing 1 is the same as in the embodiment shown in FIG. 3, but in the case of FIG. is,
A ball screw nut 4 is disposed within the housing 40.
1 is rotatably supported. A ball screw 42 that is screwed into the ball screw nut 41 has a square slide shaft portion 42a formed at its tip, and expands and contracts in the axial direction while being guided by a guide member 43 having a square hole screwed onto the telescoping arm housing 40. It's becoming like that. ball screw nut 41
is an internal gear 41a formed at one end thereof and a spur gear 44 fixed to the tip of the rotating work shaft 31.
It is rotationally driven by the rotational movement of the rotary work shaft 31 via the rotary work shaft 31 . Therefore, this square slide shaft portion 42
The telescoping arm consisting of a extends and contracts in the axial direction of the wrist housing 2 at the oscillating position, so a suitable work member such as a cone-shaped drilling tool, pusher, etc. can be attached to the tip of the arm. Tools, welding tools, or robot hands can be attached to it to perform any desired work.

5 and 6 are longitudinal cross-sectional views showing other embodiments of the present invention, both of which are modifications of the embodiment shown in FIG. 4. Referring to these figures, the drive unit 4 in the base housing 1 can be seen.
is the same two-axis configuration as in Fig. 1, and the third
From the housing 1 to the bellows 3 as shown in Fig. 4
A third output shaft 30 and a bellows coupling 32 projecting inward are not provided. Instead, in the modified embodiment shown in FIG. 5, the drive unit 5' in the wrist-side housing 2 has a three-shaft configuration, one of which has an output shaft 31' that connects the other two output shafts extending toward the base. A spur gear 44 in a telescoping arm housing 40, described in FIG. 4, is fixed to the tip of the output shaft 31', which protrudes in the opposite direction to the shafts 8 and 9. The other parts are the same as those in FIG. 4, and therefore, this output shaft 31' has the same function as the rotary work shaft 31 described above. Drive unit 5'
Due to this bias, the square slide shaft portion 42a of the ball screw 42 expands and contracts in the axial direction via the output shaft 31', the spur gear 44, and the ball screw nut 41. In the modified embodiment shown in FIG.
The drive units 4 and 5 therein both have a two-axis configuration, and therefore the internal structures of both housings 1 and 2 are exactly the same as the embodiment shown in FIG. However, in the case of FIG. 6, the driving part of the square slide shaft part 42a is provided on the base side of the telescopic arm housing 40 attached to the end of the wrist side housing 2. A stator coil 45 of the drive unit is attached to the inner end of the base side of the telescoping arm housing 40, and a permanent magnet 46 is attached to the outer peripheral end of the ball screw nut 41 concentrically with the coil. It is fixed. With this configuration, the ball screw nut 41 also functions as a rotor of the drive section with respect to the stator coil 45, so that the ball screw nut 41 is activated by biasing the stator coil 45 by a pulse signal or the like. The square slide shaft portion 42a of the ball screw 42 expands and contracts in the axial direction through the ball screw 42. The embodiment shown in FIG. 6 is convenient because while the joint structure of the housings 1 and 2 on the base side and the wrist side is shared, only the drive unit built-in unit on the telescopic arm housing 40 side can be attached and removed as necessary.

Next, the three-axis drive unit 4 shown in FIG. 3 will be explained with reference to FIGS. 7 and 8. The drive unit 4 of this embodiment includes three electric motors 3, a first, a second, and a third, in a motor housing 10.
5, 36, and 37 are arranged concentrically one on top of the other. Output shaft 7 of the third motor 37 at the top end
is formed into a hollow shape, and the gear 1 is fixed to its outer circumference.
3 meshes with the driven gear of the screw-type linear slide mechanism (not shown), which is located in a cross section perpendicular to FIG. 1 and described in connection with FIG. The output shaft 6 of the second motor 36 located in the intermediate portion is also formed in a hollow shape, and the third motor 3
The motor housing 10 passes through the output shaft 7 of 7.
Another gear 12 extending outward and fixed to the outer periphery of this output shaft 6 meshes with driven gears 21, 27 of screw linear slide mechanisms 16, 17 shown in FIG. The output shaft 30 of the first motor 35 at the lowest stage similarly extends through the hollow output shaft 6 of the second motor 36, and its tip is connected to the bellows coupling 32 described in FIGS. 3 and 4. connected to. These first, second and third motors 35, 36,
37 are each driven separately, and in this way three different driving powers are extracted from positions on the same axis. The two-shaft drive unit 5 in the other wrist-side housing 2 in FIG. 3 and the drive unit 5' with output shafts protruding to both sides as shown in FIG. 5 have the same structure of essential parts.

The joint part is made into a unit by a pair of housings 1 and 2, and a plurality of these are connected in the axial direction as necessary, and the work members explained in FIGS. 3 to 6 are attached to the most advanced housing. As a result, a modular articulated robot and mechanical parts with an extremely high overall degree of freedom and functionality can be obtained. Furthermore, in the present invention, the motor (pulse motor) that provides joint motion is integrated into the drive unit, and the drive unit itself is also compactly housed within the housing of the joint. As shown in the figure, a power cable, an address bus, and a data bus are installed, and power and signals can be supplied from these to each motor in the drive unit, thereby making it possible to increase the number of joints as desired.

[Brief explanation of the drawing]

FIG. 1 is a vertical center sectional view of a joint structure according to an embodiment of the present invention, FIGS. 3 shows another embodiment of the present invention, FIG. 4 shows still another embodiment of the invention, and FIGS. 5 and 6 show modified embodiments of FIG. 4. 7 is a perspective view of the drive unit applied to the present invention, FIG. 8 is a longitudinal sectional view of FIG. 7, and FIG.
The figure shows the power supply and signal supply system of the drive unit. 1... Base side housing, 2... Wrist side housing, 3... Bellows, 4, 5, 5'... Drive unit, 6, 7, 8, 9, 30, 31'... Output shaft, 31... Rotating work axis, 16, 17, 18,
19... Screw type linear slide mechanism, 22, 41...
...Ball screw nut, 23, 42...Ball screw, 42a...Square slide shaft, 2
4, 26, 33, 34...Slide shaft portion, 32...
...Bellows coupling spring, 40...Telescopic arm housing, 45...Stator coil, 46...Permanent magnet.

Claims (1)

[Scope of Claims] 1. A cylindrical first housing and a second housing, a nut rotatably supported within the first and second housings, and a threaded portion screwed into the nut. a slide shaft provided at one end, and a slide shaft provided at the other end with a shaft projecting axially from the end of the housing and supported by the housing in a non-rotatable and axially movable manner; and four screw-type linear slide mechanisms arranged in parallel to each other in each housing, and the two screw-type linear slide mechanisms of each housing are different from each other with respect to the central axis of the articulated arm. The slide shaft protruding from the first housing and the slide shaft opposing the slide shaft protruding from the second housing are bent by spherical fitting between the opposing shaft parts, respectively. a connection means for freely connecting the housings; a drive unit fixed to the first and second housings respectively; an output transmission means for transmitting rotation of the output shaft of the drive unit to the nut; and a bellows that connects opposing ends of the housing in a relatively non-rotatable and bendable manner, and one of the slide shafts of the threaded linear slide mechanism facing the central axis of the articulated arm is connected to the bellows with the spherical fitting. The screw type linear slide mechanism is driven to extend together with the slide shaft of the screw type linear slide mechanism that is connected to the screw type linear slide mechanism by the spherical fit, and the other is driven to contract together with the slide axis of the screw type linear slide mechanism that is connected to the screw type linear slide mechanism by the spherical fit. joint structure. 2 The drive unit has two output shafts protruding in a telescoping manner, one of which is in an opposing relationship with respect to the central axis of the articulated arm of the four screw type linear slide mechanisms. According to claim 1, the output shaft is connected to the nuts of the two screw-type linear slide mechanisms located in the other two screw-type linear slide mechanisms, and the other output shaft is connected to the nuts of the remaining two screw-type linear slide mechanisms. joint structure.