JP2009255195A - Parallel mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify maintenance work such as maintenance and replacement of an easily consumable drive shaft by easily attaching/detaching the drive shaft to/from the output shaft of a motor and an operating shaft, in a parallel mechanism. <P>SOLUTION: This parallel mechanism includes a plurality of drive motors 7 arranged on a base 2, arm units driven and operated by the drive motors, an operating head 5 supported by the arm units, and the drive shaft 6 transmitting rotative power of the motors provided on the base to the operating shaft provided on the operating head. The drive shaft 6 is composed of ball spline shafts 22, 23 transmitting the rotative power while being elongated and contracted, and universal joints 21 respectively provided to the input end and output end of the ball spline shafts. The input end and output end of the drive shaft are detachably connected to the output shaft of the motor and operating shaft through friction fasteners 26, 27. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a parallel mechanism used as, for example, an industrial robot, and more particularly to a rotary parallel mechanism in which an operation head is supported by a plurality of pairs of arm units.

  The basic structure of this type of parallel mechanism is known, for example, from Patent Document 1. There, a parallel mechanism with a base, three servo motors arranged evenly on the lower surface of the base, three arm units driven by the servo motors, and an operation head supported by the three arm units, etc. Is configured. A drive shaft is provided between the base and the operation head to transmit rotational power while expanding and contracting. On the lower surface side of the operation head, a hand for capturing a processing target is provided.

  Each arm unit is composed of a drive arm that is swiveled up and down by a servo motor and a rod that transmits the swivel motion of the drive arm to the operation head. The rod is connected to the drive arm and the operation head by a ball joint. It is. The drive shaft is composed of a drive cylinder and a passive cylinder that are connected in a telescopic manner, and upper and lower ends of the drive shaft are connected to an output shaft of the motor and an operation shaft incorporated in the operation head via a cardan joint. The drive cylinder and the passive cylinder are each configured by a cylindrical body having a non-circular cross section. By changing the drive direction and drive amount of each drive arm, the operation head can be freely displaced in a predetermined three-dimensional space. This type of parallel mechanism can also be seen in US Pat.

JP 2001-277164 A (paragraph number 0010, FIG. 2) JP 2005-528993 A (paragraph number 0019, FIG. 1)

  The drive shaft in the present invention includes a drive-side spline shaft and a passive-side spline shaft that are connected to each other in a telescopic manner. The upper and lower ends of the drive shaft are connected to the output shaft of the motor and the operation shaft incorporated in the operation head via a universal joint. When the parallel mechanism is operating, the drive shaft expands and contracts while tilting following the three-dimensional motion of the operation head, and is simultaneously driven forward or reverse. For this reason, a high load is applied to the fitting portion of the drive side spline shaft and the passive side spline shaft and the universal joint, and it is easy to wear out in a relatively short period of time compared to other components such as the drive arm. For these reasons, when a certain usage time (for example, one year) has elapsed since the start of the operation of the parallel mechanism, it is necessary to replace part or all of the drive shaft with a new part.

  It is an object of the present invention to improve the connecting structure of the drive shaft to the motor output shaft and the operation shaft so that the drive shaft can be quickly attached and detached, thereby simplifying maintenance work such as maintenance and replacement of the drive shaft. There is to do.

  The parallel mechanism of the present invention operates a plurality of drive motors arranged on the base, an arm unit driven by the drive motor, an operation head supported by the arm unit, and a rotational power of the motor provided on the base. And a drive shaft that is transmitted to an operation shaft provided in the head. Therefore, by connecting the input end and output end of the drive shaft detachably to the motor output shaft and operation shaft via friction fasteners, the entire drive shaft can be connected to the motor output shaft and operation shaft. It can be separated from the shaft.

  The drive shaft is composed of a ball spline shaft including a drive-side spline shaft and a passive-side spline shaft that can transmit rotational power while expanding and contracting, and universal joints provided at the input end and the output end of both the spline shafts. The universal joint is detachably connected to the output shaft and the operation shaft of the motor via friction fasteners.

  The friction fastener is a friction lock type fastener. The friction lock type fastener includes an inner ring and an outer ring that are adjacent to each other through a tapered surface, and a screw structure that moves and operates either the inner ring or the outer ring in the axial direction.

  The friction fastener is a screw body that is arranged in a state orthogonal to a joint body having a connection hole that fits around the output shaft and a slit formed in the peripheral wall of the connection hole, and operates to reduce the diameter of the peripheral wall of the connection hole. And consist of

  The friction lock type fastener is supported so that it can rotate relative to either the inner or outer ring adjacent to the inner or outer ring via a taper surface and the inner or outer ring, and the other of the inner or outer ring moves in the axial direction via a screw. It consists of a nut to be operated.

  In the parallel mechanism of the present invention, each of the input end and the output end of the drive shaft connecting the motor and the operation shaft is detachably connected to the output shaft and the operation shaft of the motor via a friction fastener, The drive shaft can be separated from the previous output shaft and operation shaft. In other words, when removing the drive shaft, there is no need to separate the peripheral structure of the drive shaft such as the motor, the operation shaft or the operation head, and the drive shaft can be easily removed or assembled simply by attaching and detaching the friction fastener. I did it. Therefore, according to the parallel mechanism of the present invention, when the degree of wear of the drive shaft, which is easily consumed due to a high load, is checked or replaced with a new drive shaft, the drive shaft is quickly attached and detached for maintenance work. It can be simplified.

  According to the drive shaft composed of a ball spline shaft that can be extended and contracted and a universal joint provided at each of its input and output ends, the motor power is effectively applied to the operation shaft while following the three-dimensional displacement of the operation head smoothly. Can be transmitted. For example, compared to conventional drive shafts composed of non-circular drive cylinders and passive cylinders, and cardan joints provided at the upper and lower ends of both cylinders, the rotational power of the motor can be transmitted more efficiently, and friction during expansion / contraction transmission The resistance can be reduced to smoothly follow the high-speed movement of the operation head. In addition, the universal joints at the input and output ends are detachably connected to the motor output shaft and operation shaft via friction fasteners, so that the drive shaft can be assembled simply by attaching and detaching the friction fasteners. All can be separated or assembled.

  When the friction fastener is configured as a friction lock type with the inner and outer rings adjacent to each other via a tapered surface and a screw structure that moves one of the two, the drive shaft and its connection target can be connected simply by tightening the screw structure. Can be connected or separated simultaneously. Therefore, it is possible to more easily carry out inspection, replacement work, and the like of the degree of wear of the drive shaft without the trouble of attaching and detaching the drive shaft. For example, compared with the case where the output end of the drive shaft and the operation shaft are connected via an intermediate coupling body, and the output end and the intermediate coupling body, and the intermediate coupling body and the operation shaft are coupled with pins that pass through the coupling. The structure can be simplified and reduced in weight. Therefore, the weight acting on the operation head can be reduced, and the driving load acting on the arm unit can be reduced by that amount. Or the conveyance weight by an operation head can be increased. In addition, the drive shaft and the object to be connected are fixed by the surface contact of the inner and outer rings, so that the power transmission efficiency between the drive shaft and the object to be connected is eliminated by eliminating the shakiness of the connecting part that is unavoidable when connecting pins. it can.

  A friction fastener is composed of the joint body and the screw body that reduces the diameter of the peripheral wall of the connection hole provided in the joint body. When the drive shaft and the object to be connected are connected by the friction fastener, the screw body is tightened. By doing so, the drive shaft can be attached to and detached from the connection target. For example, if the output shaft of the motor is to be connected and the output shaft is at a high position, or if the periphery of the output shaft is surrounded by a plurality of drive motors, the wrench on the side of the friction fastener It is difficult to perform the tightening operation by rotating the shaft around the vertical axis. However, if the screw body is arranged in a direction perpendicular to the slit of the joint body, the tightening / loosening operation is a rotation operation around the horizontal axis, so the screw body can be tightened / tightened without any trouble. The friction fastener can be easily attached and detached even in a narrow work space. As a result, the drive shaft can be easily and quickly separated and assembled with respect to the connection target.

  According to the friction fastener constituted by the inner ring and the outer ring, and a nut that moves one of the inner and outer rings in the axial direction via a screw, the output end of the drive shaft can be simply tightened. And the operating shaft can be connected or disconnected at the same time. Therefore, compared with the case where one of the inner and outer rings is moved by a plurality of screw bodies, the output end of the drive shaft can be separated and assembled more easily.

(Example) FIGS. 1-6 shows the Example which applied the parallel mechanism based on this invention to the conveyance robot. As shown in FIG. 2, the parallel mechanism is configured with a high-rigidity base 1 installed in a state straddling a table or a conveyor as a base. Specifically, a base 2 fixed to the upper wall of the gantry 1, three drive motors 3 disposed on the lower surface of the base 2, three arm units 4 driven by the drive motor 3, and each arm unit 4 comprises an operation head 5 supported by 4 and a drive shaft 6 arranged at the center. The base 2 is located above the operation space of the operation head 5, and a motor 7 that rotationally drives the drive shaft 6 is provided on the upper surface thereof.

  Three motor brackets 10 are provided at equal intervals on the lower surface of the base 2, and the drive motor 3 is assembled to these motor brackets 10. The drive motor 3 integrally includes a servo motor and a speed reducer, and outputs reciprocating turning power decelerated by the speed reducer. As shown in FIG. 3, the three drive motors 3 are arranged on the base 2 with their central axes constituting each side of an equilateral triangle, and the figure center of the equilateral triangle is the axis center of the drive shaft 6. Matched to the position. The previous motor 7 is also composed of a motor having the same structure as that of the drive motor 3, and outputs forward rotation power and reverse rotation power decelerated by a reduction gear.

  The arm unit 4 includes a drive arm 12 that is swiveled up and down by the drive motor 3 and a rod 13 that transmits a swiveling operation of the drive arm 12 to the operation head 5. An arm boss 14 is fixed to the base end of the drive arm 12, and this arm boss 14 is fixed to the output shaft of the drive motor 3. As shown in FIG. 3, the rod 13 includes a pair of link rods 15 arranged in parallel and a spring unit 16 provided near the upper and lower ends of the link rods 15 to draw and urge both link rods 15. It is.

  The upper and lower ends of the rod 13 are connected to the drive arm 12 and the operation head 5 by ball joints 17 respectively. As described above, according to the arm unit 4 connected via the ball joint 17, the drive arm 12 can be freely reciprocated up and down by the drive motor 3 to freely move the operation head 5 in a predetermined three-dimensional space. Can be displaced. Of the space in which the operating head 5 can be displaced three-dimensionally, an operating range having a diameter of 1040 mm and a height of 200 mm on the reference plane is the working area of the operating head 5. A line connecting the ball centers of the opposing ball joints 17 is parallel to the central axis of the drive motor 3 described above.

  The operation head 5 is composed of a triangular plate-like block, and an operation shaft 20 that inherits the rotational power of the drive shaft 6 is rotatably supported at the center thereof. As shown in FIG. 4, the operation shaft 20 includes a shaft portion 52 that is rotatably supported by a cross roller bearing 51, a flange 53 provided at the lower end of the shaft portion 52, and a connection provided at the upper end of the shaft portion 52. It comprises a shaft 54. Using the flange 53, a capturing structure such as a suction tool or a hand is attached.

  The drive shaft 6 is transmitted while expanding and contracting the rotational power of the motor 7. In order to reduce frictional resistance during expansion and contraction transmission and to smoothly follow the high-speed movement of the operation head 5, the drive shaft 6 includes a ball spline shaft and a universal joint 21 connected to the upper and lower ends of the ball spline shaft. To do. As shown in FIG. 1, the ball spline shaft is composed of an upper half drive spline shaft 22 and a lower half passive spline shaft 23. In order to easily perform maintenance and replacement of the drive shaft 6, the input end and the output end of the drive shaft 6 are rubbed against the output shaft (connection target) 25 and the previous operation shaft (connection target) 20 of the motor 7, respectively. It connects so that attachment or detachment is possible via the fastener 26 * 27.

  As shown in FIGS. 4 and 5, the friction fastener 26 connected to the output shaft 25 of the motor 7 includes a joint body 28 having a connection hole 29 that fits outside the output shaft 25, and a peripheral wall of the connection hole 29. A hexagon socket head cap screw (screw body) 30 that is operated to reduce the diameter is used. The joint body 28 is a shaft body having a hexagonal cross section. A slit 31 is formed in a part of the peripheral wall of the connection hole 29, and a bolt insertion hole 32 and a screw hole 33 are formed with the slit 31 interposed therebetween. is there. The joint body 28 may be formed of a round shaft or a shaft body having a polygonal cross section.

  A fastening seat 34 is formed at the outer end of the bolt insertion hole 32 to receive the operation head of the hexagon socket head cap screw 30. A connecting shaft 35 is formed in the lower part of the joint body 28, and this connecting shaft 35 is fixed to a joint body 36 on the driving side of the universal joint 21 with a bolt or a pin (not shown). The connecting shaft 35 may be fixed to the joint body 36 with both bolts and pins. With the output shaft 25 fitted in the connecting hole 29, the hexagon socket head cap screw 30 is screwed into the screw hole 33 in a state orthogonal to the slit 31, thereby reducing the diameter of the peripheral wall of the connecting hole 29 and the friction fastener. 26 can be connected and fixed to the output shaft 25.

  As shown in FIGS. 4 and 6, the friction fastener 27 connected to the operation shaft 20 is a commercially available friction lock type fastener (trade name: Mechalock). The friction fastener 27 is supported in a relatively rotatable manner by a cylindrical inner ring 38 that is open at both upper and lower ends, a cylindrical outer ring 39 that is externally fitted to the inner ring 38, and a flange wall 40 that projects around the lower end of the outer ring 39. The nut (screw structure) 41 is composed of three members. The inner ring 38 and the outer ring 39 are adjacent to each other through a tapered surface 42, and a slit (not shown) that allows expansion / contraction deformation is formed on each cylindrical wall. The tapered surface 42 is formed so as to expand upward from the flange wall 40 side of the outer ring 39 toward the upper end of the outer ring 39. A screw shaft (screw structure) 43 that meshes with the nut 41 is formed on the lower peripheral surface of the inner ring 38.

  By inserting the connecting shaft 54 of the operating shaft 20 into the connecting hole 44 of the inner ring 38 having the above-described configuration and further screwing the nut 41 with the outer ring 39 fitted into the joint body 45 on the passive side of the universal joint 21, 38 is pulled toward the nut 41 along the axis. As the inner ring 38 moves, the outer ring 39 is deformed to expand in diameter, and its peripheral surface is pressed against the inner peripheral surface of the joint body 45 on the passive side. At the same time, the inner ring 38 is deformed in a reduced diameter, and the connecting hole 44 comes into pressure contact with the connecting shaft 54. As a result, the operation shaft 20 and the universal joint 21 can be firmly connected via the friction fastener 27. When the nut 41 is tightened, it is necessary to avoid the passive joint body 45 and the operation shaft 20 of the universal joint 21 from rotating together. Therefore, flat surfaces 46 and 47 for engaging the spanner are formed at opposing positions of the operation shaft 20 and the shaft peripheral surface of the joint body 45, respectively.

  When removing the drive shaft 6, the operation is performed according to the following procedure. First, the brake of the drive motor 3 is released, the operation head 5 is moved to a position where it is easy to work, and the previous brake is operated to fix the arm unit 4 so that it cannot move. Next, the exclusive spanner is simultaneously engaged with the flat surfaces 46 and 47 described above, and the operation shaft 20 and the joint body 45 are fixed so as not to rotate. In this state, another spanner is engaged with the nut 41 and rotated to the loose side to release the frictional engagement state by the inner and outer rings 38 and 39. Thereafter, the hexagon socket head cap screw 30 of the upper frictional fastener 26 is operated to the loose side with a hexagon stick wrench to release the connection state between the output shaft 25 of the motor 7 and the joint body 28. Finally, the drive shaft 6 can be separated from the operation shaft 20 and the joint body 45 by inserting the drive side spline shaft 22 into the passive side spline shaft 23 and reducing the overall length of the drive shaft 6.

  Although the periphery of the operation shaft 20 is surrounded by three sets of arm units 4, the space above the operation shaft 20 is open, and the operation head 4 can be freely moved to a position where it can be easily operated. Therefore, the nut 41 of the friction fastener 27 connected to the operation shaft 20 can be easily tightened or loosened from the side by a spanner. The friction lock type friction fastener 27 alone can connect the connecting shaft 54 and the joint body 45 at the same time, so that there is an advantage that the connecting structure can be simplified and reduced in weight and high torque can be transmitted.

  As described above, it is preferable to connect the output shaft 25 of the motor 7 and the drive shaft 6 with the friction lock type friction fastener 27 that can simplify the coupling structure, but there is a problem. When the output shaft 25 of the motor 7 is at a high position and the periphery of the output shaft 25 is surrounded by three drive motors 3, it is difficult to perform a tightening operation from the side of the nut using a spanner. There is. For these reasons, the friction fastener 26 connected to the output shaft 25 is composed of the joint body 28 and the hexagon socket head cap bolt 30, and the hexagon socket head bolt 30 can be tightened or loosened with a hexagon bar wrench that can be operated even in a narrow work space. I am doing so.

  In the above-described embodiment, the friction fastener 27 for moving one of the inner and outer rings 38 and 39 in the axial direction with the nut 41 has been described. However, the present invention is not limited to this structure. The friction fastener 27 may be configured such that one of the inner and outer rings 38 and 39 is moved in the axial direction by a plurality of bolts (screw bodies). The drive shaft 6 is preferably a ball spline shaft. However, when the displacement speed of the operation head 5 is low, general shaft couplings that can transmit rotational power while expanding and contracting can be applied. Similarly, universal joints 21 can be applied to other types of universal joints. In the friction fastener 26, a screw body can be constituted by a nut and a bolt held and prevented from rotating, and the nut can be tightened to reduce the diameter of the peripheral wall of the connection hole 29. In the above embodiment, the friction fastener 26 is disposed on the input end side of the drive shaft 6 in consideration of the fact that the friction fastener 26 is at a high position and the drive motor 3 is disposed in the vicinity thereof. Although another friction fastener 27 is disposed on the output end side, it is not necessary. The parallel mechanism has various sizes depending on the application, and the mounting directions thereof are also various. Therefore, the arrangement position of the friction fasteners 26 and 27 may be selected according to the use of each parallel mechanism. For example, both friction fasteners 26 and 27 can be disposed upside down, or the same friction fastener 26 (or friction fastener 27) can be disposed at both ends of the drive shaft 6.

It is a partially broken front view of the state which isolate | separated the drive shaft. It is an AA arrow directional view in FIG. It is a top view of a parallel mechanism. It is a partially broken front view of the state which assembled | attached the drive shaft. It is the BB sectional view taken on the line in FIG. It is sectional drawing of a friction lock type friction fastener.

Explanation of symbols

2 Base 3 Drive motor 4 Arm unit 5 Operation head 6 Drive shaft 7 Motor 20 Operation shaft 21 Universal joint 22 Drive spline shaft 23 Passive spline shaft 25 Output shaft 26 Friction fastener 27 Friction fastener 28 Joint body 29 Connection hole 30 Screw body (bolt)
31 Slit 38 Inner ring 39 Outer ring 41 Screw structure (nut)
42 Tapered surface 43 Screw structure (screw shaft)

Claims (5)

A plurality of drive motors arranged on the base, an arm unit driven by the drive motor, an operation head supported by the arm unit, and rotational power of the motor provided on the base are supplied to the operation head. A parallel mechanism having a drive shaft that is transmitted to the provided operation shaft,
Each of the input end and output end of the drive shaft is detachably connected to the output shaft of the motor and the operation shaft via a friction fastener. The drive shaft is composed of a ball spline shaft including a drive side spline shaft and a passive side spline shaft capable of transmitting rotational power while expanding and contracting, and a universal joint provided at each of an input end and an output end of both the spline shafts. And
The parallel mechanism according to claim 1, wherein the universal joint is detachably connected to the output shaft and the operation shaft of the motor via the friction fasteners. The friction fastener comprises a friction lock type fastener;
The friction lock type fastener includes an inner ring and an outer ring that are adjacent to each other through a tapered surface, and a screw structure that moves one of the inner ring and the outer ring in the axial direction. Item 3. The parallel mechanism according to Item 1 or 2.   The friction fastener is disposed in a state orthogonal to a joint body having a connection hole that fits outside the output shaft, and a slit formed in the peripheral wall of the connection hole, and the diameter of the peripheral wall of the connection hole is reduced. 4. The parallel mechanism according to claim 1, wherein the parallel mechanism is constituted by a screw body to be operated.   The friction lock type fastener is supported by an inner ring and an outer ring adjacent to each other through a taper surface, and either the inner ring or the outer ring so as to be relatively rotatable, and the other of the inner and outer rings is connected to a shaft via a screw. 4. The parallel mechanism according to claim 3, wherein the parallel mechanism is constituted by a nut that is moved in a direction.

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