WO1997039505A1

WO1997039505A1 - Energy-transfer connection for a robot

Info

Publication number: WO1997039505A1
Application number: PCT/DK1997/000150
Authority: WO
Inventors: Jan Ebbe SØRENSEN
Original assignee: Georg Fischer Disa A/S
Priority date: 1996-04-12
Filing date: 1997-04-09
Publication date: 1997-10-23
Also published as: DK171673B1; DK42496A; AU2380597A

Abstract

A rotatable (A6) working head (4) adapted to carry a gripper, a tool or the like (not shown) requiring an energy supply, the holder (36) for said working head (4) being pivotable (A5) about a pivot bearing (34a) relative to an arm (34) of a robot (the proximal parts of which are not shown), is supplied with energy through an energy-transfer conduit (62), such as an electric cable or a pressure-fluid hose, from either a local energy source (61) or (in a manner not shown) from an external energy source. According to the invention the conduit (62) is held in permanent tension by a tensioning device (68) acting upon the conduit (62) through a pulley (63), the conduit (62) further being guided by guide pulleys (65, 65a) rotatably supported on the arm (34). With this arrangement, it is possible, without having to run the conduit (62) internally in the various parts of the robot, to prevent the conduit (62) from being caught by nearby objects, such as may be encoutered when operating in cramped spaces, e.g. in a deburring cell (not shown) in a foundry.

Description

ENERGY-TRANSFER CONNECTION FOR A ROBOT

FIELD OF THE INVENTION

The present invention relates to an energy-transfer connection for a robot, such as set forth in the preamble of claim 1.

BACKGROUND ART

It is known within the prior art to arrange energy-transfer connections to manipulators or robot arms in the form of flexible conduits (electric cables or pressure-fluid hoses) curving flexibly outwards about the articulation or articulations, so that the conduit can change its distance to the articulation or articulations and in this manner accommodate chages in distance occurring during the movements of the articulation or articulations. Such a flexible connection is e.g. described in SE-B-457,744. This flexible connection does, however, have the disadvantage of requiring a free space about the manipulator or robot, in which the conduit can curve outwards. This is inconvenient when operating in cramped spaces; conversely, it can require more space for the work processes.

It is particularly inconvenient if two articulations are situated close together and that the most distal articulation is a rotary one, about which the conduit is wound, since this causes a great change in length at the more proximal articulation.

Attempts have been made within the prior art to solve this problem by building the energy-transfer means into the manipulator and robot arm, requiring the connecting means to be capable of rotation and/or elongation. For this reason, such connections are vulnerable and costly, and they may place constructional demands on the robot in a manner to counteract an advantageous and simple construction of the latter. DISCLOSURE OF THE INVENTION

Thus, it is the object of the present invention to provide an energy-transfer connection of the kind referred to initially, that does not require much space about the robot while being simple and robust in construction without the need of special adaptation of the robot arm, and according to the present invention this object is achieved by means of the features set forth in the characterizing clause of claim 1. These features make it possible to arrange the energy-transfer means close to the robot arm or arms, thus requiring no extra space about the latter.

With the embodiment set forth in claim 2, the necessity of transferring each and every change in length past all the articulations of the robot to the tensioning means is avoided.

The embodiment set forth in claim 3 makes it possible in a simple manner to transmit a tensioning force past a pivot articulation.

The embodiment set forth in claim 4 is especially well-suited for use in cramped spaces, and when it is desired to utilize the length of an elongate robot part in an optimal manner, or when the energy-transfer conduit is to run past articulations, between which it is desired to provide the tensioning force.

The embodiment set forth in claim 5 makes it a particularly simple matter to provide the tensioning force.

With the embodiment set forth in claim 6 it is achieved that the energy-transfer conduit is flexed and/or tensioned in a gentle manner. The embodiment set forth in claim 7 makes it possible in a simple manner to attain a greater degree of freedom with regard to the angles, through which the pivot articulation may be pivoted.

The embodiment set forth in claim 8 makes it possible to achieve a greater length in cases, in which the energy-transfer connection runs close to the robot, or to situate inertially heavy energy-transmission means at a greater distance from the distal end of the robot.

The embodiment set forth in claim 9 makes it possible in a relatively uncritical manner to supply energy to a location close to the distal end of the robot, where it is converted to the required fluid pressure; this transfer can e.g. take place to a pressure accumulator or a pressure-generating device. This embodiment is especially suited when the working head is provided with a gripper with the function "grip - let go", in one working cycle requiring high pressure in a short interval and having a low pressure in the rest of the cycle.

On the other hand, the embodiment set forth in claim 10 makes it possible to exploit the advantages of the invention when using solely an external energy source.

The embodiment set forth in claims 11 and 12 makes it possible in a particularly advantageous manner to adapt standard manipulators or robots for operation in cramped spaces, and by also using the features of claim 9 it is possible in a simple manner to convert a standard robot into a special robot, since the space provided e.g. for a welding transformer on a standard robot close to the distal end of the manipulator is utilized for a power transformation according to the invention being transferred to the working head, making it possible to transmit high pressures to the latter, at the same time making it possible to arrange the energy transfer up to said power transformation in a less critical manner. BRIEF DESCRIPTION OF THE DRAWING

In the following detailed part of the present description, the invention will be explained in more detail with reference to the exemplary embodiments of an energy-transfer connection according to the invention shown in the drawings, in which

Figure 1 shows a standard robot with six degrees of freedom,

Figures 2 and 3 show a part of a robot with distal articulations, in elevation and plan view, respectively, Figure 4 shows the distal articulation as viewed from below towards the surface, to which the working head is attached,

Figure 5 shows a tensioning pulley,

Figure 6 shows a tensioning pulley with a return pulley, and

Figures 7 and 8 show a spacer assembly with spacer pulleys or rollers, in elevation and plan view, respectively

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 shows a standard manipulator or robot 3 having five or six degrees of freedom and consisting of

- a base 30 constituting the proximal datum,

- a first robot member 31 connected to the base 30 and rotatable relative to the base in directions A1, - a second robot member 32 capable of pivoting about a pivot pin 31a in directions A2,

- a third robot member 33 capable of pivoting about a pivot pin 32a in directions A3,

- a fourth robot member 34 capable of turning about a longitudinal axis in directions A4,

- a fifth robot member 35 capable of pivoting in directions A5 about a pivot pin 34a situated in the distal part 37 of the fourth member 34, and finally - a distal working-head holder 36 capable of rotating about a longitudinal axis in directions A6 relative to the fifth robot member 35.

The working-head holder 36 is adapted to carry the working head 4, that may be a gripper, a tool or the like. The bearing, about which the working-head holder 36 can rotate relative to the fifth robot member 35 in the directions A6, is adapted to allow rotation through e.g. 720°.

The bearing, about which the fifth robot member 35 can pivot about the pivot pin 34a relative to the distal part 37 in the directions A5, is a pivot bearing allowing movement through less than one turn, e.g. 240° or ± 120°. The fourth robot member 34 with its forwardmost or distal part 37 constitutes an elongate rigid robot element, to which additional equipment can be secured, such as e.g. a welding transformer.

Standard robots and manipulators of this kind with five or six degrees of freedom are manufactured in great numbers, e.g. for the automobile industry, for which reason they provide a highly advantageous quality/price ratio as compared to tailor- -made manipulators with a lower number of degrees of freedom.

When using a standard or specially made robot, it will frequently be necessary to arrange the energy-transmission conduits close to or inside the robot in order to avoid damage to the conduit, or else it may be necessary to take the conduit into account when planning the movements to be carried out by the robot.

Figures 2 and 3 show an embodiment especially well-suited for running an energy-transmission cable 62 past one or a number of articulations to a working head 4 or another articulation, causing great changes in the length demand for the cable 62, at the same time as this cable 62 is held close to the robot 3. The exemplary embodiment shown is especially advantageous by holding the cable 62 close to the robot in a simple and reliable manner, so that the robot can operate in a cramped space, such as will e.g. be the case in a deburring cell. In the example shown, rotation of the holder 36 about the axis for the A6 movement will cause the calbe 2 to be wound around the holder 36, and this winding can take place through a number of turns, e g two During this winding process great changes in length are required for the cable 62 to be held close to the robot, and this requirement is fulfilled by providing a tensional force urging the cable 62 towards the proximal side of the robot 3 relative to the working-head holder 36 In the example shown, this tensioning force for the cable 62 is directed towards the guide pulleys 65 and 65a This tensioning force is provided for the cable 62, extending from an energy source 61 and the latter's base plate 50, 60, to which the cable 62 is secured, by arranging the cable 62 about a tensioning pulley 63 situated between the assembly constituted by the parts 50, 60, 61 and the guide pulley 65, and by exerting a force on this tensioning pulley 63 to pull the cable 62 away from the direct path between the assembly 50, 60, 61 and the guide pulley 65 In this example, this force on the tensioning pulley 63 is provided by a pulling device 68 comprising a spπng- tensioned cord or the like exerting an approximately uniform pulling force, said pulling device being connected to the tensioning pulley 63 via a fork 69 as shown in Figure 5

This tensioning of the cable 62 tending to pull it away from the working-head holder 36 towards the guide pulley 65 operates well, as long as the holder 36 is in the position shown in Figure 2, i.e pointing downwards at right angles to the fourth robot member 34, but if the holder 36 is pivoted upwardly to a position, in which it points in the opposite direction, the cable 62 will be drawn inwardly towards the pivot beanng The angular excursion interval for the A5 movements, in which the cable 62 can be pulled into abutment against the bearing proper or the abutment region, will typically compnse an interval extending from a position, in which the holder 36 protrudes at right angles from the side, at which the cable 62 is run, to a position, in which the holder 36 has been pivoted away from this side, e g through an angle in the direction A5 of 210° In the abutment region, the cable 62 will additionally be subjected to wear and friction, especially when the holder 36 rotates in this position and pulls the cable back and forth during winding in and out In order to avoid this wear and possible breakdown of the cable 62, the invention provides spacer pulleys 67, cf. Figures 7 and 3, at the outer periphery of the articulation about the pivot pin 34 in locations, at which the cable 62 would otherwise lie in abutment. These spacer pulleys 67 keep the cable 62 clear of the parts of the articulation proper and reduce the friction.

In the exemplary embodiment shown, the spacer pulleys 67 are provided in the form of a spacer-pulley assembly 66 constituting a self-contained unit as shown in Figures 7 and 8 and adapted to be mounted on the pivoting articulations of a standard robot. The spacer-pulley assembly 66 may be provided with an arm 71 , in size and shape adapted to the parts of the pivot bearing and the clearance at same, as well as the desired positioning of the spacer pulleys 67. In addition, the spacer-pulley assembly 66 comprises fixing means, e.g. in the form of a fixing plate 72 with fixing holes 70 for securing to the articulation by means of screws and the like. The spacer pulleys 67, rotationally supported by the arm 71 , may have various shapes, e.g. like elongate cylindrical rollers capable of covering all the locations where the cable 62 can lie in abutment, or they can constitute grooved pulleys as shown in the drawing. If the spacer pulleys 67 are in the form of spacer rollers with guide grooves, and if the angle, at which the cable 62 extends from the holder 36, changes during the pivoting movement as indicated in Figure 4, the arm 71 can be formed with a partial helical twist about the pivot pin corresponding to the locations where the cable would lie in abutment, when in a given angular position being pulled into abutment against a spacer pulley 67.

In the example shown in the drawing, the cable 62 is a flexible tube transferring hydraulic or pneumatic energy to the working head 4 from an energy source 61 , but it could also be an electric cable. In the embodiment shown, the energy source 61 is situated on a base plate 50, 60, in a standard robot being secured to an elongate rotor member 34, normally providing space for additional equipment, such as e.g. a welding transformer.

In another embodiment (not shown) with an external energy source, the energy transfer conduit can extend from the external source of energy to e.g. a location on the fourth robot member 34, at which the energy source 61 is situated in the embodiment shown in Figures 2 and 3

It is also possible to provide the tensioning of the cable 62 by means other than those described above, e g by using a spnng-loaded winding drum

If space is at a premium, and if it is desired that the length of an elongate robot member 34 be exploited optimally, or if the energy-transfer conduit is to run past at least two articulations in case it is desired to provide the tensioning force between two articulations, this can be achieved by means of a return pulley 64, possibly being subjected to a tensioning force as shown in Figure 6

Using the invention, it is a simple matter to convert a standard robot into a special robot suited for operation in cramped spaces and capable of carrying out special operations, such as e g calibrating and truing-up grinding wheels etc This can be earned out by providing a base plate 50, 60 with the requisite additional equipment in the form of energy converters 61 and other units 54 for calibrating, truing-up or other operations, and securing, by means of fixing screws 56, this base plate 50, 60 on a standard-robot arm m e g a location intended for additional equipment, and in addition attach a spacer-pulley assembly 66 on a pivoting or rotary articulation, as well as a unit comprising at least one guide pulley 65, 65a on a robot component, and even possibly attaching a tensioning unit 68 to a robot component that is or will be maintained substantially immovable relative to the robot component, to which the base plate 50, 60 is attached

The special arrangement of the energy transfer makes it possible to achieve higher operating speeds, of great importance in deburnng operations In this connection, it should be noted that an automatic casting machine can in many cases produce castings eight times faster than it has been possible to debur them up to the present, the difference in operating speed depending on the size of the casting Thus, it is an advantage that the robot can be moved close up to tools and workpieces without the necessity of taking the energy transfer conduit into account when elaborating the pattern of movement of the robot.

The arrangement of energy-transfer conduits described above and the technical solutions it comprises makes it possible in a simple manner to tailor a robot to the specific wishes of a customer.

In connection with the system for deburring or grinding a workpiece by means of a robot being the subject of the present Applicant's co-pending Danish patent application No. 0425/96, the present invention makes it easy to transform a standard robot into a special robot, e.g. for the deburring purposes. In connection with the integrated deburring cells for deburring castings being the subject of the present Applicant's co-pending Danish patent application No. 0423/96, such a special robot makes it possible to provide a fast-operating deburring cell, in a simple manner having been adapted to an immediate need.

LIST OF PARTS

3 Manipulator/Robot

4 Working head 30 Base

31 First robot member 31a Pivot pin

32 Second robot member 32a Pivot pin 33 Third robot member

34 Fourth robot member 34a Pivot pin

35 Fifth robot member

36 Working-head holder 37 Distal part of fourth member

A1 First degree of freedom, rotary

A2 Second degree of freedom, pivoting

A3 Third degree of freedom, pivoting A4 Fourth degree of freedom, rotary

A5 Fifth degree of freedom, pivoting

A6 Sixth degree of freedom, rotary

50 Baseplate 54 Units

56 Fixing screws

60 Baseplate

61 Energy source/~converter

62 Energy-transmission cable 63 Tensioning pulley

64 Return pulley

65 Inner guide pulley 65a Outer guide pulley

66 Spacer-pulley assembly

67 Spacer pulley

68 Pulling device/tensioning unit

69 Fork

70 Fixing holes

71 Arm (for pulleys)

72 Fixing plate

Claims

1 Energy-transfer connection for a manipulator or a robot (3), said manipulator or robot comprising a) a robot base (30) constituting a proximal datum, b) a distal working head (4) with a gripper, a tool or the like, to which energy is to be supplied, c) at least one most distal articulation (36, A6) with one degree of freedom, especially of a rotational nature, situated proximally of said working head (4), d) at least one pivot articulation (32a, 33, A3, 34a, 35 A5) with one degree of freedom situated proximally of the most distal articulation or articulations, whereas e) said energy-transfer connection comprises a flexible conduit (62) transferring energy from a source of energy to said working head (4) and adapted to accommodate the length changes occurring in the part of said conduit past pivot articulation or articulations and at least one most distal articulation, c h a r a c t e r i z e d by f) tensioning means (63, 68) adapted to tension said conduit (62) with a force directed towards said tensioning means (63, 68) and/or guide means (65, 65a) situated proximally of the pivot articulation, and g) spacer means (66, 67) on the pivotable part of the pivot articulation, said spacer means comprising at least two pulleys or rollers (66) adapted in succession to swing in between the pivot articulation and the conduit (62) for supporting the latter when the pivot articulation is pivoted in an abutment region, in which the conduit is subjected to a force attempting to draw the conduit in towards the axis of the pivot articulation

2 Energy-transfer connection according to claim 1 , c h a r a c t e r i z e d in that said tensioning means (63, 68), e g a spring-loaded winding drum, is/are situated on a robot part (32, 33, 34, 37) situated proximally of the pivot articulation and adapted to apply said tension through said conduit in at least one point lying proximally of the pivot articulation as a force directed substantially parallel to an elongate robot part (32, 33, 34) situated at said point.

3. Energy-transfer connection according to claim 1, characterized in a) that said tensioning means comprise a pulley (63, 64) being connected in a pre-tensioning manner to an elongate robot part (32, 33, 34) situated proximally of the pivot articulation with a tensioning force directed substantially parallel to said elongate part, and b) that said energy-transfer conduit (62) runs from an "upstream" side of said pulley and about the latter leaving it on a "downstream" side to continue to said pivot articulation, at which the conduit is supported on at least one spacer roller or pulley, when the pivot articulation is moved into the abutment region.

4. Energy-transfer connection according to claim 3, characterized by an additional pulley (63, 64), past which said energy-transfer conduit (62) extends in order to change its direction.

5. Energy-transfer connection according to claim 3 or 4, characterized in that said pulley and/or additional pulleys (63, 64) is/are pre-tensioned, such as with a tension spring or pulling device (68) extending or pulling in a direction substantially parallel to said elongate part.

6. Energy-transfer connection according to any one or any of the claims 1-5, c h a ra ct e r i z e d in that said spacer pulleys or rollers (67) at the pivot articulation are rotatable and so situated, that straight connection lines between and tangent to the smallest outer circumferences do not intersect parts of said pivot articulation.

7. Energy-transfer connection according to any one or any of the claims 1-5, characterized by a guide pulley or roller (65a) immediately proximally of the pivot articulation and so situated, that the energy-transfer conduit (62) runs between said pulley or roller and a part of the robot being connected to the pivot articulation, in such a manner that said pulley or roller supports the conduit, when the pivot articulation moves rearwardly through an angle

8 Energy-transfer connection according to any one or any of the claims 5-7, characterized in that the energy-transfer conduit (62) runs past at least one additional articulation (32a, 33, A3; 34, A4, 34a, 35, A5) of a pivoting nature, in which the additional articulation or articulations is/are provided with spacer pulleys or rollers, whereas the pre-tensioning of the conduit is provided either proximally of or between the rotational articulation and an additional pivot articulation by means of at least one pre-tensioned puliey or roller (63, 64)

9 Energy-transfer connection according to any one or any of the claims 1-8, cha racterized in that the energy-transfer conduit (62) is a pressure-fluid conduit leading from a pressure source (61) situated on an elongate robot part (32, 33, 34) situated proximally of the rotational articulation.

10 Energy-transfer connection according to any one or any of the claims 1-9, ch a r a cte ri z e d in that the energy-transfer conduit (62) is run from an external energy-source and is secured to said elongate robot part (34)

11 Energy-transfer connection according to any one or any of the claims 1-10, c h a ra ct e ri z e d in that the rotational articulation or the articulation or articulations with pulleys or rollers (67) is/are among the distal articulations (32a, 33, A3; 34, A4; 34a, 35, A5) on a standard robot with five or six degrees of freedom

12 Energy-transfer connection according to any one or any of the claims 1-11, characterized in that the spacer means are in the form of a unit (66, 67, 70, 71 , 72) adapted to be attached to a rotational articulation