Data processing: generic control systems or specific application – Specific application – apparatus or process – Robot control
Reexamination Certificate
2002-09-09
2004-09-21
Gandhi, Jayprakash N. (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Robot control
C700S250000, C074S490060, C901S015000, C901S029000
Reexamination Certificate
active
06795750
ABSTRACT:
TECHNICAL AREA
The present invention relates to an industrial robot with a robot upper arm. The present invention also refers to a turning device for supply lines for an industrial robot with a rotatable robot arm, a method for drawing supply lines, use of a turning device on an industrial robot with a rotatable robot arm and use of the industrial robot or the turning device in a welding process.
THE PRIOR ART
It has become ever more common in industrial robots to allow the supply lines for process media, such as electrical power, cooling water, air or signals, for the tool to run internally within the upper arm of the robot. What is described as “supply lines” hereunder denotes one or more lines and/or wires for electricity, fluids, other media, etc., and it can also denote an empty flexible protective cover in which one or more lines or cables can be arranged. The said process media can, for example, be intended for point welding. The desired tool is attached to a tool connector at the free end of a robot upper arm. The tool connector is firmly attached to a rotatable device with bearings which in the subsequent text will be denoted by “the turning device”. The said turning device comprises a forward disk-shaped section, also known as the turning disk, for the attachment of a tool to it. There exist today some standard sizes of the flange that constitutes the outermost forward part of the turning disk and that is used to attach a tool. The turning device also comprises a rear section, attached to the turning disk, that is mounted on bearings and arranged to rotate in a wrist on the robot upper arm. It is desirable that supply lines be drawn through all the said parts, such as the robot upper arm and the turning device, wholly or partially internally, within the robot. The lines are in this way protected from damage and breakage, at the same time as loose supply lines are avoided that get in the way around the working space of the robot. However, the supply lines are subject to both turning and bending during the various rotations of the respective parts. For example, a rotatable part of the wrist and simultaneously the turning device can each rotate +/−300° (in the description given here 300° denotes rotation through a complete circle), which is why the total twisting of supply lines that pass along these parts can be exposed to a twisting of 600°. What is known as a “tilt” movement (a bending) can achieve a movement of the supply lines of up to +/−120°. In order to reduce wear and to increase the lifetime of the supply lines, the supply lines should be firmly clamped as little as possible. This makes the supply lines easier to exchange. Supply lines may need to be exchanged as often as once a month during normal use. Supply lines should also possess a certain axial freedom of motion, between, for example, conductors (individual wires) in a line. Thus the supply lines should not be firmly clamped in the robot arm or be bent so severely that the said rotational movements are inhibited. In known solutions the supply lines are attached to connectors that are firmly fixed in the turning device, which connectors extend radially from the turning device and relative to the axis of rotation of the tool. The supply lines are in this way submitted to a very severe bending within the turning device and the robot arm. Too severe bending of the supply lines with a small radius of curvature gives rise to a significant risk of endurance fracture of parts that are included in the supply lines, such as, for example, copper conductors. Process supply lines require a relatively large radius of curvature, and it is therefore particularly important to exercise caution against too sharp and small bending radius of curvature of the supply lines when drawing process lines. In addition to this it can be mentioned that where the supply lines pass out through connectors in the turning device at the end of the robot arm the supply lines become extensive and bulky. Extensive supply lines encroach upon the working area and make access difficult in order to work in cramped spaces.
The drawing of supply lines essentially completely internally forwards through the turning disk and onwards to the tool is also known in a special design. This, however, is not desirable, since it must be possible to use different types of tool and a tool connector must be standard. Each user of industrial robots has specific desires concerning, for example, special tools that are to be used. The supply lines are for this reason normally drawn externally, on the outer surface of the tool connector/turning device and external to the robot arm at its forward part.
EP-A2-0873826 concerns an industrial robot comprising a wrist joint, comprising three wedge-shaped devices, in which a third wrist device has a flange with connectors for tools. Supply lines are arranged within the robot arm and are further arranged to be drawn out radially at the third wrist device, out of the wrist device. In this way, the supply lines are attached to connectors that are firmly fixed in the wrist device, which connectors pass radially outwards from the wrist device relative to the axis of rotation of the tool. The construction according to EP-A2-0873826 does not specify a solution to the problems that have been described according to the prior art above. These wrist devices do not permit a straight feed-through of supply lines. Supply lines that are subject to sharp bending in a right angle are subject to extreme loading, leading to a reduction in lifetime.
There has long existed a need within the industry to draw supply lines more directly along a robot arm. One function that has been sought-after for a long time is the ability to draw supply lines internally through the complete robot arm and turning device, whereby the supply lines are drawn right up to the turning disk of the turning device for further connection to a tool attached at the turning disk.
DESCRIPTION OF THE INVENTION
The present invention aims at achieving supply lines drawn simply in a robot arm for an industrial robot, which supply lines resist the mechanical loading that they are subject to during rotational movement of the robot arm whereby an increase in the lifetime of the supply lines can be achieved. Furthermore, the intention is to achieve an arrangement of supply lines that is simple, cost-effective, easy to mount or dismount and/or exchange, and easy to repair. A further aim is that at least the designs of the pathway of the supply lines, the tool attachment, etc., at the tool are to be made as compact and flexible as possible in order to make it possible for the robot to gain access to space-restricted work surfaces and in this way prevent the supply lines from encroaching onto the working space.
The solution is achieved with an industrial robot with the characteristics specified in claim
1
. To be more precise, claim
1
according to the present invention relates to an industrial robot that comprises an upper arm that can be rotated around a first axis, a wrist that is supported by the upper arm and can be rotated around a second axis, a hollow turning device that is supported by the wrist and that can be rotated around a third axis and that at its forward end comprises a turning disk for attachment of a tool, at least one supply line that runs along the upper arm, whereby the turning device comprises a collar section with a conical envelope surface that is connected to the turning disk, through which is arranged at least one opening for the reception of a supply line that passes through the turning device, whereby the opening has an axial extension along a normal perpendicular to the envelope surface, where the supply line is arranged to pass through the opening in a direction that has a component parallel to the third axis, which opening is arranged to control in a transverse direction and to allow in a longitudinal direction displacement of the supply line. Since the supply line is arranged through the collar section in a direction that has a co
ABB AB
Dykema Gossett PLLC
Gandhi Jayprakash N.
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