Parallel robot, robot system, and assembly method for transfer system

A parallel robot includes a base casing, a plurality of arms, and an end unit. The base casing contains a plurality of actuators. Each of the arms is coupled to one of the actuators. The end unit is coupled to the plurality of arms. A communication hole for allowing piping and/or wiring to continue is formed in the base casing at its side facing the end unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2013-120739, filed Jun. 7, 2013, the entire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to a parallel robot, a robot system, and an assembly method for a transfer system.

2. Description of the Related Art

JP 2013-39650 A discloses a parallel robot that includes a base casing, a plurality of arms, and an end unit. The base casing contains a plurality of actuators. The arms are each coupled to one of the actuators. The end unit is coupled to the plurality of arms.

SUMMARY

A parallel robot according to the present disclosure includes: a base casing containing a plurality of actuators; a plurality of arms, each of the arms being coupled to one of the actuators; and an end unit coupled to the plurality of arms, wherein a communication hole for allowing at least one of piping and wiring to continue is formed in the base casing at a side thereof facing the end unit.

A robot system according to the present disclosure includes: the parallel robot; an end effector provided on the end unit of the parallel robot; and at least one of a hose and a cable for driving the end effector, wherein at least one of the hose and the cable is routed through the communication hole to the end effector.

An assembly method for a transfer system according to the present disclosure includes: installing a parallel robot, the parallel robot including: a base casing containing a plurality of actuators; a plurality of arms, each of the arms being coupled to one of the actuators; and an end unit coupled to the plurality of arms, the base casing having a communication hole for allowing at least one of piping and wiring to continue formed therein at a side thereof facing the end unit; routing at least one of the hose and the cable through the communication hole; attaching an end effector to the end unit; and coupling at least one of the hose and the cable to the end effector.

DETAILED DESCRIPTION

An embodiment will now be described in detail with reference to the drawings. Like components or components with like functions are indicated with like reference figures, and the description thereof is not duplicated.

A transfer system (a robot system)100illustrated inFIG. 1is a picking system for performing a pick-and-place work in which a parallel robot1picks up a workpiece W transferred by a conveyor (a workpiece transfer device)2and place the workpiece at another location. The transfer system100includes a ceiling board3, the conveyor2arranged under the ceiling board3, two parallel robots (parallel link robots, delta robots)1secured to the ceiling board3at its lower side with bolts or the like, and two controllers5and two suction blowers (external devices)7arranged on the ceiling board3at its upper side. Note that the number of parallel robots1is not limited to two. It may be one, or it may be three or more.

The parallel robot1includes a robot body10, three arms20, an end unit30, and an end effector40. The robot body10, which includes three actuators12, is attached to the ceiling board3at its lower side. The three arms20are each coupled to one of the three actuators12. The end unit30is coupled to the three arms20. The end effector40is mounted on the end unit30. The parallel robot1allows the end effector40to retain the workpiece W and enables the three arms20to move the end effector40in cooperation, so that the workpiece W is transferred.

The ceiling board3may be supported horizontally by a plurality of poles (not shown), or it may be suspended horizontally from a ceiling of a plant. Alternatively, the ceiling of the plant may be used as the ceiling board3. The ceiling board3functions as an installation member to retain the parallel robot1and also functions as a division member to divide vertically the surroundings of a base casing11(to be described hereinafter) of the robot body10. In other words, the transfer system100includes the installation member and the division member. The installation member may be configured with a frame different from the ceiling board3. The ceiling board3has two openings3acorresponding to the two parallel robots1. The openings3aare used for the maintenance of the parallel robots1and for routing piping and/or wiring to the parallel robots1. A transparent side wall6is installed around the conveyor2. The ceiling board3and the side wall6divide a work space S1of the parallel robots1from an external space S2.

Each controller5is connected through a cable5ato the robot body10to control the three actuators12. Each suction blower7generates suction force for adherence to the workpiece W. The suction force is transmitted through a hose7ato the end effector40.

The parallel robot1will now be described in detail. As described inFIGS. 2 to 4, the robot body10includes the base casing11and the three actuators12contained in the base casing11. The base casing11includes a case11A and a lid11B. The case11A has a substantially circular bowl-like shape in a plan view. The case11A has at its bottom three bulges11abulging downward. The three bulges11aare arranged along a circumferential direction. The lid11B has a plate-like shape and covers the case11A at its top. The lid11B is detachably attached to the case11A with a plurality of fasteners19.

The three actuators12are arranged in such a manner that they each correspond to one of the three bulges11a. As illustrated inFIG. 4, each actuator12includes a motor13and a speed reducer14. The speed reducer14is accommodated in each bulge11a, and the motor13is arranged above the speed reducer14. The motor13and the speed reducer14are secured to a bracket11bprovided in the case11A.

The motor13includes an output shaft13aand a pulley13b. The output shaft13aprotrudes in the horizontal direction, and the pulley13bis mounted on an outer periphery of the output shaft13a. The speed reducer14includes an input shaft14a, a pulley14b, and an output shaft14c. The input shaft14aprotrudes in a direction identical to that of the output shaft13a, and the output shaft14cprotrudes at a side opposite to the input shaft14a. The pulley14bis mounted on an outer periphery of the input shaft14a. A timing belt15is applied over the pulley13band the pulley14b. This transmits power of the motor13to the input shaft14a, allowing the output shaft14cto output the power.

As illustrated inFIG. 5, a first opening11cis formed in the bottom of the case11A in an area A1surrounded by the bulges11a. The opening11cis equivalent to a communication hole for allowing at least one of the piping and the wiring to continue. As described hereinafter, the three arms20are coupled to the speed reducers14in the bulges11a, and thus the area A1is surrounded also by the three arms20. A second opening11dis formed in the lid11B at a position corresponding to that of the opening11c. The opening11dis also equivalent to the communication hole for allowing at least one of the piping and the wiring to continue.

A tubular member16is attached around the opening11cand protrudes upward. The tubular member16has a cylindrical shape and includes at its outer circumference at its lower end a flange16a. The tubular member16is arranged substantially concentrically with the opening11c. The flange16ais on an upper surface of the bottom of the case11A and secured to the case11A through bolt fastening or the like.

A tubular member17is attached around the opening11dand protrudes downward. The tubular member17has a cylindrical shape and includes at its outer circumference at its upper end a flange17a. The tubular member17is gradually flared upward toward the flange17ato have a tapered portion17b. The tubular member17is arranged substantially concentrically with the opening11dand has been passed into the opening11dfrom above. The flange17ais on an upper surface of the lid11B and secured to the lid11B through bolt fastening or the like.

The tubular member17has at its lower end a fitting portion17cthat fits an outer periphery of the tubular member16. The fitting of the fitting portion17cand a distal end of the tubular member16couples the tubular member16and the tubular member17. The tubular member16and the tubular member17, which are coupled with each other, constitute a tubular unit P1that allows the lower side and the upper side of the base casing11to communicate with each other. The tubular unit P1is positioned in an area surrounded by the three actuators12(seeFIG. 6). The tubular unit P1constitutes a communication hole H1that allows the opening11cand the opening11dto communicate with each other and penetrates the base casing11between its lower and upper sides. The inner diameter of the communication hole H1is determined in consideration of the size, the number, and the like of hoses and/or cables for the piping and/or the wiring to be routed.

As illustrated inFIG. 2, each arm20includes a base linkage22, which is equivalent to an upper arm, and a coupling linkage26, which is equivalent to a forearm. The base linkage22extends outward from between two neighboring bulges11a. The coupling linkage26couples a distal end22aof the base linkage22with the end unit30and includes two rod-like members27. An example of materials for the base linkage22and the coupling linkage26includes carbon fiber reinforced plastics (CFRP) and other lightweight material.

A proximal end22bof the base linkage22is connected to the output shaft14cof the speed reducer14. The base linkage22turns by an operation of the actuator12to move the distal end22aup and down. In the description hereinafter, “the base linkage22turns to the upper side” means that the base linkage22turns so as to raise the distal end22a, and “the base linkage22turns to the lower side” means that the base linkage22turns so as to lower the distal end22a. The distal end22ahas a pair of spherical projections23. The pair of spherical projections23, which are disposed side by side along a direction parallel to a turning axis line of the base linkage22, protrude outward.

The two rod-like members27constituting the coupling linkage26extend in parallel with each other. Each rod-like member27includes at its upper end27ba cup27a. The cup27aand a spherical projection23constitute together a ball joint. The upper ends27bof the two rod-like members27are coupled with each other through an elastic member28, such as a coil spring, with their cups27aeach covering one of the spherical projections23from the outside.

A lower end27dof each rod-like member27is coupled with a coupler32of the end unit30. The coupler32includes a pair of spherical projections32a. The lower end27dincludes a cup27c. The cup27cand the spherical projection32aconstitute together a ball joint. The lower ends27dof the two rod-like members27are coupled with each other through an elastic member29, such as a coil spring, with their cups27ceach covering one of the spherical projection32afrom the outside. The ball joints render the coupling linkage26turnable three-dimensionally with respect to the base linkage22and the end unit30turnable three-dimensionally with respect to the coupling linkage26.

The end unit30is movable by the three arms20working in cooperation. For example, the three base linkages22turn to the upper side simultaneously to raise the end unit30and turn to the lower side simultaneously to lower the end unit30. One base linkage22turns to the upper side and another base linkage22turns to the lower side, so that the end unit30moves toward the base linkage22that has turned to the upper side.

As illustrated inFIGS. 7 and 8, the end unit30is covered with a housing31. The end unit30includes a base33, which couples the three arms20, and an expansion35, which is positioned below the base33and shifted laterally with respect to the base33. The end effector40is mounted on the expansion35rotatably.

The base33includes a circular top plate33a, a cylindrical side wall33b, a dividing plate33cparallel to the top plate33a, and an actuator34accommodated in these components set forth. Three couplers32described above are provided on an outer periphery of the side wall33bin the circumferential direction to surround the base33. The pair of spherical projections32aprotrude from each coupler32at its both sides in the circumferential direction of the side wall33b.

The actuator34is secured on the dividing plate33cand connected through a cable34ato the controller5. The actuator34is controlled by the controller5. The actuator34is configured with, for example, a motor, a speed reducer, and a sensor, and includes an output shaft34b. The output shaft34b, which is oriented downward along a central axis CL2of the side wall33b, has been inserted in the dividing plate33c. A distal end of the output shaft34bis positioned in the expansion35, and a pinion pulley34cis provided on the distal end. The cable34ais routed along the arm20(seeFIG. 2).

The expansion35is circular in a plan view and its central axis CL3is parallel with the central axis CL2of the side wall33bof the base33. The central axis CL3is positioned outside an area A2surrounded by the three couplers32in the base33and orthogonal to a plane including the area A2. The central axis CL3is also positioned outside the side wall33band between two neighboring couplers32. The distance between the central axis CL3and the central axis CL2is determined in consideration of the shape of the area A2, the size of the hose7a, and the like.

The expansion35includes a rotation member36. As illustrated inFIG. 8, the end effector40is secured to the rotation member36at its lower side. In other words, the rotation member36constitutes a retainer that retains the end effector40. The rotation member36rotates about the central axis CL3with the actuator34as a driving source. In other words, the rotation member36rotates about the rotation axis CL3positioned outside the area A2surrounded by the plurality of couplers32. The expansion35has an upper opening35aand a lower opening35b. The upper opening35aand the lower opening35bare formed where the rotation member36is accommodated.

The rotation member36has a cylindrical shape and includes at its one end a flange-like pulley36a. The rotation member36has at its center a through hole36cextending in an axial direction. The through hole36cand the upper opening35aand the lower opening35bof the expansion35form a communication hole37for allowing at least one of the piping and the wiring to continue. The communication hole37extends along the central axis CL3and penetrates the expansion35including the rotation member36in a vertical direction. The inner diameter of the communication hole37is determined in consideration of the size, the the number, and the like of hoses and/or cables for the piping and/or the wiring to be routed.

The rotation member36, which is accommodated in the expansion35with the pulley36afacing upward, is attached rotatably through a bearing35cto a periphery of the lower opening35b. The lower end36bof the rotation member36has been inserted in the lower opening35b. A timing belt34dis applied over the pulley36aand the pinion pulley34c. The actuator34rotates the rotation member36through the timing belt34din response to a command from the controller5. Arrangement of both the actuator34and the rotation member36in the end unit30simplifies a mechanism to transmit power from the actuator34to the rotation member36. As the mechanism to transmit the power from the actuator34to the rotation member36, a mechanism with a gear in place of the timing belt34dmay be employed.

The end effector40moves together with the end unit30and turns together with the rotation member36. The end effector40, which is of a type that retains the workpiece W by suction, includes a pillar41secured to the rotation member36, two adherence units42, and a flange45to which the adherence units42are secured. The pillar41is attached to the rotation member36at a lower end surface36dwith a bolt or the like (not shown). The flange45is provided on an outer periphery of the pillar41, and the two adherence units42are arranged so that the pillar41is interposed therebetween. Note that the number of adherence units42may be one, three or more.

An adherence unit42includes an adherence port42athat opens downward. The adherence unit42is connected through the hose7ato the suction blower7. A valve (not shown) is provided at a midpoint of the hose7a, and opening and closing of the valve is controlled by the controller5. The valve switches between an ON state and an OFF state in response to a command from the controller5, with the ON state being a state in which the adherence unit42communicates with the suction blower7and an OFF state being a state in which the adherence unit42does not communicate with the suction blower7. In the ON state, the adherence port42aadheres to the workpiece W by the suction force from the suction blower7. In the OFF state, the adherence port42aloses the suction force and releases the workpiece W. The transfer system100allows the valve to switch to the ON state so that the end effector40adheres to the workpiece W. While adhering to the workpiece W, the end effector40is moved to a target position. The valve is then allowed to switch to the OFF state to release the workpiece W. This operation is performed repeatedly. Through this, work, such as alignment and packing of the workpiece W, is performed.

As illustrated inFIG. 2, the hose7a, which extends from the suction blower7positioned in the external space S2, is routed through the communication hole H1into the work space S1. The hose7a, which passes through the communication hole H1, naturally passes through the openings11cand11d. The hose7a, which is routed into the work space S1, is routed through a space surrounded by the three arms20toward the end unit30, and then through the communication hole37of the end unit30to the end effector40to be connected to the adherence unit42.

As described above, the parallel robot1allows piping to be routed from the base casing11through the opening (the communication hole)11cin the bottom of the base casing11toward the end unit30. For the parallel robot1, an obstacle to motion of the arms20cannot be arranged between the base casing11and the end unit30. Thus, no structure that constitutes an obstacle to the piping is present between the opening11c, which faces the end unit30, and the end unit30. Hence, the piping can be routed toward the end unit30with ease by using a route from the opening11ctoward the end unit30.

Close attention is demanded for routing the piping toward the end unit30so as not to let the hose7acaught by a surrounding structure while the end unit30moves. With the opening11cpositioned in the area surrounded by the three arms20, the hose7ais surrounded by the three arms20at least in proximity to the base casing11. Because of this, it is less likely that the hose7ais caught by a structure around the parallel robot1, and thus the piping can be routed toward the end unit30with greater ease.

The parallel robot1especially allows the hose7ato be arranged in the space surrounded by the three arms20also in proximity to the end unit30because the hose7ais also routed through the communication hole37, which is positioned in proximity to the lower ends of the arms20. Thus, the piping can be routed toward the end unit30with greater ease.

Additionally, the opening (the communication hole)11d, which is formed in the base casing11at its side opposite to the end unit30, allows the piping to be routed through the base casing11. Thus, the piping can be routed from the suction blower7, which is positioned in the external space S2, toward the end unit30, which is positioned in the work space S1, without performing the drilling into the ceiling board3or the side wall6.

The communication hole H1, which penetrates the base casing11from its side facing the end unit30to its side opposite to the end unit30, functions as a guide. Hence, the piping and/or the wiring that continues from the side facing the end unit30to the side opposite to the end unit30can be routed with greater ease. Additionally, a peripheral wall of the communication hole H1divides a route R1for the piping and/or the wiring from an accommodation spaces for the actuators12, and thus improved protection can be provided for the actuators12.

The communication hole H1is constituted by the tubular unit P1, which is provided in the base casing11and allows the side facing the end unit30and the side opposite to the end unit30to communicate with each other. Through use of this configuration, the communication hole H1can be formed with a tubular member of a simple shape with ease.

The tubular unit P1is positioned in the area surrounded by the three actuators12. Thus, the communication hole H1can be formed by using effectively the space surrounded by the actuators12. The motor13and the speed reducer14of the actuator12especially are arranged one above the other. This reduces the area occupied by the actuator12in the horizontal direction. This also contributes to the allocation of space for the communication hole H1.

The end unit30includes the actuator34for rotating the end effector40. With the actuator for rotating the end effector40not arranged at the base casing11, there is no need to place a rotation transmission shaft between the base casing11and the end unit30. Thus, the piping and/or the wiring can be routed toward the end unit30with greater ease.

An assembly method for the transfer system100will now be described. The parallel robot1is arranged under the ceiling board3and the robot body10is attached to the ceiling board3. In other words, the parallel robot1is installed. Then, the controller5and the suction blower7are installed on the ceiling board3at its upper side. Then, the controller5and the robot body10are connected with each other with a cable5a. Then, the hose7ais routed through communication hole H1toward the end unit30. Then, the end effector40is attached to the end unit30. Then, the hose7ais routed through the communication hole37to the end effector40to be connected to the adherence unit42. Such a work procedure can be changed as appropriate.

Although an embodiment has been described, the invention is not limited thereto, and various changes are possible without departing from the spirit of the invention. With at least the opening11cformed, the route from the opening11ctoward the end unit30can be used for routing the piping and/or the wiring, yielding the effect of facilitating the routing of the piping and/or the wiring. Thus, the communication hole H1, the opening11d, and the communication hole37may be excluded. The opening11cdoes not have to be positioned in the area surrounded by the three arms20. The suction blower7does not have to be provided on the ceiling board3at its upper side, and it may be, for example, provided in the base casing11. The hose7amay be connected to a pipe disposed in a plant as a shared system for transmitting suction force, in place of the suction blower7, which is special to the parallel robot1.

The end effector40may be a robot hand to grip the workpiece W. An example of the robot hand includes a robot hand driven by air pressure and a robot hand driven by an electric actuator. An air-supply hose is routed through the communication hole H1in the case of the air pressure needed as driving source, and a power-supply cable is routed through the communication hole H1in the case of electric power needed as driving source. An effect similar to that of the routing of the hose7ais yielded for the routing of the air-supply hose or the routing of the power-supply cable.

The communication hole H1can be also used to route a cable for sending and receiving control signals to and from the end effector40, and the communication hole H1can be used to route the cable34ato be connected to the actuator34. In any of the cases, an effect similar to that of the routing of the hose7ais yielded.