Patent Application
20050034552
The invention relates to an industrial robot, a method for equipping the robot with a cable harness, a cable harness, and use of the robot.
In industrial robots, it is common practice to arrange the cable harness internally of the robot to protect the cable harness. When manufacturing industrial robots with an internally drawn cable harness, there is a need to impart great mobility to a robot tool in the form of bending and rotational movements. The movements of the tool during operation entail bending and rotational movements of the cable harness. In an industrial robot, therefore, the cable harness is subjected to movements repeated in cycles, and these movements result in wear on individual strands included therein. For one thing, the individual strand is worn, and, for another, wear arises between the individual strands in the cable harness. If the wear is allowed to continue for a long time, it leads to damage to the cable harness, which in turn leads to unwanted and, in the worst case, sudden shutdowns. In the light of these facts, a cable harness is judged to have a certain service life depending on, inter alia, the extent to which it is bent and turned during the work cycles of the robot. The service life of the cable harness is dependent on the robot application in question. Therefore, the operating routine comprises replacing a worn-out cable harness with a new cable harness in good time, according to scheduled service intervals, before a risk of damage and shutdown arises.
The determination cable harness here means a process cable harness for, for example, electric power for welding electrodes, power supply for robot tools and a robot, electric signal cables for transmission of information from sensors at the tool, hoses for compressed air and cooling medium, or combinations thereof in accordance with the client application at hand. In addition, the determination comprises spare circuits for, for example, the various needs of the client.
In the patent document EP 0 873 826, a wrist for an industrial robot is shown. The wrist is built up of three parts that are rotatably connected to one another and designed so as to form a continuous open channel. Cables and wires for the power supply are drawn through the three parts of the wrist and to the rear part of a tool holder. Inside the wrist part, nearest the tool holder, the cable harness is attached with a clamping device. On its way from the clamping device to the tool holder, the cable harness is adapted to branch out radially in separate lines/strands, which are each individually connected on the periphery of the tool holder. Between the clamping device and the connection on the periphery of the tool holder, each individual line/strand is arranged so as to be bent 90°. The object of the device is to completely enclose and protect the cable harness. The design permits a maximum of 90° bending of the wrist by rotation of the parts included under simultaneous bending and rotation of the cable harness.
The U.S. Pat. No. 5,549,016 shows a wrist intended for an industrial robot. A cable harness is drawn through the wrist and, in addition, each one of the strands included in the cable harness is individually connected to the unit supporting the working tool of the robot.
In the operation of industrial robots, there is a need to minimize the time for service of the robot, since a shut-down for service entails non-productive time and thus increased operating costs.
One way of reducing the time for service shutdowns is to extend the service life of the cable harness. An extended service life of the cable harness results in increased operating time between replacements of cable harnesses, whereby the time for service shutdowns in total terms decreases. Especially in the operation of industrial robots in applications with requirements for great mobility of the wrist of the robot, the need to extend the service life of the cable harness, by reducing the wear thereof, arises.
A device or apparatus that corresponds to the relevant client application is arranged on the tilt of the robot writs and, for the sake of simplicity, it is designated robot tool in the following. Examples of robot tools are a spot welding gun, a tool for handling equipment, and a laser cutter.
The movements of the robot tool cause the cable harness connected to the robot tool to be subjected to repeated bending/rotation, the strands included in the cable harness thus being displaced axially in relation to one another. The axial displacements lead to abrasion between the individual strands and between the strands and the outer casing of the cable harness. The abrasion results in unwanted wear of the cable harness. This results in a need to arrange a cable harness and to connect it such that the wear between the individual strands is minimized/eliminated and that the service life of the cable harness is increased.
All in all, the time for a service shutdown decreases when the time of each individual cable harness replacement decreases. This creates a need of arranging a cable harness in a robot such that replacement/supplementation of the cable harness takes place rapidly and simply.
This need cannot be fulfilled by any of the industrial robots shown in the cited documents, taken together.
The object of the present invention is to reduce the operating time that is lost as service time when replacing a cable harness. The object is thus to arrange an industrial robot that makes possible rapid replacements or supplementations of the whole of or parts of a cable harness and that the cable harness as such is adapted so as to have a comparatively longer service life. The cable harness is preferably arranged so that, during movement of the robot tool, the cable harness manages a bending of more than 90° while being simultaneously rotated.
According to the invention, the above-mentioned object is achieved with an industrial robot that exhibits the characteristic features described in the characterizing part of claim 1. The solution according to the invention is to arrange an industrial robot comprising a manipulator and a control system. The manipulator comprises a hollow first robot unit, a second robot unit being rotatable about a centre axis, where the first robot unit and the second robot unit are adapted for rotation and/or bending relative to one another. The second robot unit supports a robot tool, defined according to the above. A cable harness is arranged, drawn by a first end through the first robot unit and is further arranged detachably connected to the second robot unit via a connection device. The connection device comprises a body and at least one of the lines/strands, included in the cable harness, is secured in the body. The body according to the invention comprises terminals for connection of the power supply to the robot tool according to the application. In accordance with the present independent device claim, the cable harness is secured, by a first end, to a body for detachable connection to a rotating robot unit.
The industrial robot according to the invention is arranged in accordance with the dependent claims. It is part of the inventive concept that the first robot unit is adapted for rotation and/or bending and that the first robot unit is arranged in immediate proximity to the second robot unit. It is also part of the inventive concept that the robot units are arranged in spaced relationship to each other via at least one intermediate robot unit in the manipulator.
In an advantageous embodiment of the invention, an industrial robot is arranged with a cable harness which, by its first end, is drawn through the robot wrist and is detachably connected to the turning disc provided with a robot tool. The second robot unit here consists of a turning disc that supports a robot tool.
The solution according to the invention comprises shortening the time for service shutdowns by making possible simple and rapid cable harness replacements. In an advantageous embodiment, the body according to the invention is arranged axially divided into two separate parts that are coaxially series-connected and detachably connected by, for example, a quick coupler. The first part is secured to the first end of the cable harness. The second part is detachably connected to, for example, a turning disc in a robot wrist. It is to be understood here that the quick coupler withstands the high water and air pressures prevailing.
In an additional embodiment of the invention, the cable harness is provided at its first end with a body according to the invention and at its second end arranged with a dividing section, wherein the dividing section implies that the cable harness is divisible into two parts in the longitudinal direction. The cable harness is coupled by means of, for example, a quick coupler at the dividing section. This affords the possibility of simply and rapidly detaching and replacing only part of the cable harness. For example, a cable harness part according to the invention constitutes a comparatively shorter internal cable harness, which is drawn through a robot wrist and adapted to be connected to or detached from a turning disc.
It is part of the inventive concept that a body according to the invention is detachably built into the second robot unit. In a further embodiment, the body according to the invention is radially divided into at least two sub-bodies. The division into sub-bodies facilitates leading the cable harness through the narrower passages in a manipulator, which will be explained in greater detail below. The sub-bodies are then mounted into, for example, a turning disc and are then arranged detachably built in. The sub-bodies hence offer a simple connection of the power supply to a robot tool.
In a further advantageous embodiment, the body according to the invention is arranged divided into sub-bodies with compatible shapes. By compatible shapes are meant that the sub-bodies may fit into one another like pieces in a jig-saw puzzle. In this way, the sub-bodies together form a compact and detachable body. The compatible shape of the sub-bodies is shaped such that the sub-bodies hook into one another when they are fitted into one another. Alternatively, the sub-bodies are retained by a holder device when the cable harness is drawn through the manipulator, the holder device being removed when the cable harness is in position in the manipulator.
The solution according to the invention comprises extending the service life of a cable harness by reducing the internal wear in the cable harness and then, in particular, by eliminating the axial changes in length that occur in the wrist portion of a cable harness when bending/rotating a robot tool.
In one advantageous embodiment of the invention, a cable harness is arranged during manufacture to be rotated around the longitudinal axis of the cable harness in accordance with the dependent claim 11. Installed in an industrial robot, the cable harness constitutes a detachable part length of the cable harness in accordance with the dependent claim 10 and is, for example, the above-mentioned section through the wrist. The central portion of a cable harness consists of a tube/hose.
The inventive concept comprises a cable harness according to the independent claim 13. A body according to the invention, defined as above, is secured at one end of the cable harness. The body is arranged with at least one terminal for connection of the power supply to a robot tool. Advantageous embodiments of the cable harness according to the invention are arranged in accordance with the dependent claims 14-17.
Claims 16 and 17 describe an advantageous embodiment of the invention wherein the cable harness is arranged by providing a central tube/hose, during manufacture, with a quick-coupling unit at one end and a body according to the invention at its other end. Thereafter, the strands are arranged radially around the tube/hose, whereupon they are twisted helically at least one turn around the longitudinal axis of the tube and the cable harness and are attached to the body and to the quick-coupling unit, respectively. According to the inventive concept, thinner hoses may also be arranged twisted in the cable harness in the same way as the above-mentioned strands.
By manufacturing the cable harness along a longitudinal section rotated one or several turns around the longitudinal axis of the cable harness and then mounting it so as to rotate with the second robot unit and, in use, subjecting it to bending, an axial displacement and formation of slack occur in each individual strand over each twist turn. The axial displacement and the formation of slack cancel each other out over each twist turn and hence no axial displacement of the strands takes place upon bending. The above-mentioned internal wear on the cable harness is thus eliminated. It is further part of the inventive concept to arrange the cable harness with dividing sections such that it may be divided into a number of part lengths.
The inventive concept comprises all industrial robots that comprise a first and a second hollow robot units, rotatable around their respective longitudinal axes, adapted for bending and/or rotation relative to each other. This description is not to be seen as a limitation of the invention but only as guidance for a full understanding of the invention. Adaptations to robot cells with other active parts included and replacement of parts and features that are self-explanatory to a person skilled in the art are, of course, part of the inventive concept.
The invention will be explained in greater detail by description of embodiments with reference to the accompanying drawing, wherein
a-g show schematic advantageous embodiments of the invention with one end of a cable harness arranged with a body according to the invention, a turning disc and a robot tool,
a-c schematically show a robot cable harness according to the invention, arranged so as to be divided into two part lengths (connection terminals not being shown),
a-c show various advantageous embodiments of the cable harness according to the invention,
a and 12b show two alternative interfaces ahead of the turning disc as viewed from the robot foot.
The invention relates to an industrial robot and the invention is exemplified in
A cable harness 12 is drawn by its first end 13 through the upper arm 8, through the wrist 9 and up to the turning disc 10, which is shown in
a-g show different embodiments of the invention, where a body 14 according to the invention is arranged at a first end 13 of a cable harness 12 and where the cable harness is further detachably connected to a turning disc 10. The body 14, the turning disc 10 and the robot tool 11 are shown fully schematically with simple symbols in order to simply and clearly describe the various alternative embodiments according to the invention.
a shows a body 14a connected to a turning disc 10a, which in turn supports a robot tool 11a. The power supply to the robot tool 11b occurs via lines/cables 15a, which extend from the robot tool 11a and are connected to the body 14a. The respective coupling 16 is shown in
The device in
In
In
d shows an embodiment in which a body 14d according to the invention has been physically divided, by means of a radial cut, into two coaxial sub-bodies 17d and 18d, which are adapted to be connected in series with the aid of a quick coupler (not shown). The sub-body 17d is secured to the first end 13d of the cable harness 12d. The second sub-body 18d is arranged detachably connected to the first sub-body 17d and to a turning disc 10d. The power supply to the robot tool 11d is occurs via lines/cables 15d, which are connected to the second sub-body 18d. By detaching the first sub-body 17d from the second sub-body 18d, the cable harness 12d is detached from the turning disc 10d.
The embodiment shown in
The division of the body 14 according to the invention into two sub-bodies 17 and 18 makes it possible to detach a first end 13 of a cable harness 12, which is fixed in the first sub-body 17 and thereafter to pull out the first end of the cable harness in a direction towards the robot foot. This makes it simple and quick to replace a cable harness without having to detach the connection of the second sub-body 18 to, or mounting thereof in, a turning disc 10.
The body 14 according to the invention is provided with a terminal 19 for connection of the power supply 15 to the robot tool 11. In
In
g shows an embodiment that is a combination of the embodiments according to
a shows a cable harness 12 according to the invention, divided into a first 29 and a second part length 30, which part lengths are detachably interconnected through a coupling device 31. The first end 32 of the first part length 29 is adapted for detachable connection to the second robot unit 10. The second end 33 of the first part length 29 is adapted for detachable connection to the first end 34 of the second part length 30. The figure shows the part length prior to connection to the unit 10 and the device 31, respectively.
b shows a schematic picture of a cable harness according to
c schematically shows a cable harness rotated according to the above, where the body according to the invention is divided into sub-bodies, which are detachably built into a turning disc 10. The figure shows the part length 29 with the body 14 detachably built into the turning disc 10 but prior to connection to the device 31.
a-c schematically show different embodiments of the cable harness according to the invention, which is shown in
a and 12b show alternative embodiments of an interface according to the invention ahead of the turning disc as viewed from the robot foot, where the cable harness is not shown for the sake of clarity.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0102649-1 | Aug 2001 | SE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SE02/01396 | 7/18/2002 | WO |
