Note: Descriptions are shown in the official language in which they were submitted.
FF-7651-PCI/.~
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DESCRIPTION
TITLE OF TH~ INVENTION
Multi-Articulated Industrial Robot with an Offset
Robot Arm .
TECHNICAL FIELD
The present invention relates to a multi-articu-
lated industrial robot provided with a robot body, a
robot upper arm pivotally supported about a ~oint formed
at the upper end of the robot body for a swing motion
about a first horizontal axis, and a robot forearm
pivotally supported about a joint formed at the
extremity of the robot upper arm for an up-down turning
motion about a second horizontal axis and, more
particularly, to a multi-articulated industrial robot
provided with an offset robot upper arm having a back
side thereof extended along a straight line connecting
the horizontal axis of the ~oint formed at the upper end
of the robot body and the horizontal axis of the joint
formed at the extremity of the upper arm, and formed in
a structure such that it allows electric cable and pipes
to be extended along and laid against the back side.
PRIOR ART
:~ It is known that an industrial robot generally
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called a multi-articulated robot is provided with a
robot body having a fixing base at the bottom thereof, a
~` 25 robot upper arm pivotally supported about a ~oint formed
at the upper end of the body for a swing motion about a :
horizontal axis (a first horizontal axi~), and a robot ~ -
forearm pivotally supported about a ~oint formed at the
extremity of the robot upper arm for an up-down turning
: 30 motion about a horizontal axis ~a second horizontal
axis). The robot assembly of such a multi-articulated
robot is provided with electric motors for driving the . ;
robot upper arm and the robot forearm, and rotation
detectors, such as generally known encoders, for :
detecting the quantities of motions, such as swing
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motions and up-down turning motions, of the robot arms
through the detection of the quantities of motions of
the electric motors, and accordingly, cables are
essential for wiring the electrical equipment. Gen-
0rally, the robot assembly is provided with cables andwiring accessories for the electrical equipment and, if
necessary, pipes and piping accessories to supply an
auxiliary gas or the like to the robot wrist and end
effectors attached to the robot wrist. In the conven-
tional multi-articulated robot, the robot upper arm is
constructed so that portions thereof are arranged on one
and the other sides of a straight line connecting the
center of a swing motion of the joint articulating the
robot body and the robot upper arm about an axis
generally designated as "the W-axis" and the center of
an up-down turning motion of the joint articulating the
robot upper arm and forearm about an axis designated as
"the U-axis". Namely, the straight line extends
substantially through the central portion of the robot
upper arm. When the robot upper arm is thus constructed
and the cables and, when necessary pipes, are arranged
on the robot assembly, particularly when the cables are
extended along the outer surface of the robot, the
cables are liable to be damaged. If the cables are
extended through the interior of the robot assembly, the
cables are bent rapidly or stretched by the actions of
the robot arms, and thus the cables may be damaged or
cut, causing problems in the operation of the robot
assembly. Therefore, in general the cables are extended
along the cente~ axis of the robot upper arm between the- r~
robot body and the robot forearm.
Nevertheless, the extension of the cables along the
center axis of the robot upper arm requires cumbersome
work when removing the cables from the robot assembly
for maintenance, or for repairing the electric motors,
and when extending the cables again through the interior .-;
of the robot assembly after completing the maintenance - -
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work or repair.
DISCLOSURE OR THE INVENTION
Accord~ngly, an object of the present invention is
to eliminate the disadvantages of the conventional
multi-articulated industrial robot.
Another object of the present invention is to
provide a multi-articulated industrial robot having an
offset arm structure, namely, a robot arm structure
which enables work for installing cables essential to
the robot assembly or pipes and piping accessories, and
maintenance work, to be performed easily on the outer
surface of the robot assembly.
In view of the object of the invention, the present
invention provides a multi-articulated industrial robot
comprising:
a robot body having a generally vertical body
structure having a base at the bottom thereof, and a
joint having a horizontal axis and provided in the
uppermost portion of the body structure;
a robot upper arm of a length pivotally
supported at its lower end about the joint of the robot
body for a swing motion about the horizontal axis of the
~oint, and provided with a joint at its upper end; and
a robot forearm of a length pivotally
supported at its rear end in the ~oint formed at the
upper end of the robot upper arm for an up-down turning
motion;
characterized in that the robot upper arm is
formed so as to extend substantially linearly between
the respectivè horizontal axes of the joint on the upper
end of the robot body and the joint on its upper end,
the robot upper arm is provided with a back side thereof
extending along a straight line connecting the respec- -
tive centers of the horizontal axes of the ~oints, and
the back side is formed to provide an area in which
cables, such as electric cables, are permitted to lie
and extend. Since the back side is readily accessible,
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the cables can be simply extended and removed from the
robot assembly when assembling the robot assembly and
carrying out maintenance service.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advan-
tages of the present invention will be made apparent
f rom the ensuring description of a preferred embodiment
of the invention with reference to the accompanying
drawings, wherein
Fig. 1 is a sectional side elevation of a
vertical articulated industrial robot having an offset
arm structure in a preferred embodiment according to the
present invention;
Fig. 2 is a rear view taken in the direction
of the arrows along the line II-II in Fig. 1; and,
Fig. 3 is a sectional view taken along the
line III-III in Fig. 1.
BEST MODE OF CARRYING OUT THE INVENTION
Referring to Figs.1 to 3, a mul~i-articulated
industrial robot in a preferred embodiment according to
the present invention has a robot body 10 having a base
at its bottom, a front portion 10a and a rear por-
tion 10b. The robot body 10 has a box-shaped structure.
Cables and pipes can be passed into the box-shaped robot
~`~ 25 body 10 through an opening, not shown, formed in the
wall of the same.
The box-shaped robot body 10 has an offsetting
portion, i.e., a pedestal 12 extending obliquely upward
to the front from its upper portion, and a pair of
support members 14 provided respectively on rear cide of
the pedestal. A robot upper arm 20 is supported
~` pivotally for swing motion about a horizontal axis,
i.e., a W-axis, by the pedestal 12 and the support
members 14 on the upper end 16 of the robot body 10.
The robot upper arm 20 has a cylindrical lower end 22,
which is joined to the robot body 10 and supported for
turning in opposite directions on the upper end 16 of
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the robot body 10 between the support members 14 with
its center axis in alignment with the W-axis as shown in
Fig. 2. As best shown in Fig. 1, the robot upper arm 20
has an elongated tubular structure extending upward from
the upper portion of the pedestal 12 of the robot
body 10. Thus, the robot upper arm 20 having an offset
structure offset toward the front of the robot assembly
with respect to the center of the robot body 10. A
robot forearm 30 is joined at its rear end 32 for an
up-down turning motion about a horizontal axis, i.e., a
U-axis, to the upper end 24 of the robot upper arm 20.
The rear end 32 of the robot forearm 30 is provided
internally with the electric motor M3 and rotation
detector of a robot wrist driving system, not shown.
The electric motor M3 and the rotation detector must be
wired by electric cables to feed power to and to
transfer electric signals between the electrical
components including the motor M3 and the rotation
detector.
As best shown in Fig. 2, two electric motors Ml
and M2 respectively for driving the robot upper arm 20
for a swing motion and driving the robot forearm 30 for
an up-down turning motion are detachably attached to the
side surfaces of the upper end 16 of the robot body 10
respectively on the opposite sides of the cylindrical
lower end 22 of the robot upper arm 20 pivotally
supported on the upper end 16 of the robot body lO.
It is noted that the robot upper arm 20 is offset
to the front with respect to the geometrical center of
the robot body 10 and is articulated to~the robot body~
by a ~oint so that a straight line connecting the center
of the cylindrical lower end 22, i.e., the W-axis, and
the center of the rear end 32 of the robot forearm 30,
i.e., the U-axis, coincide substantially with a vertical
` 35 line when the robot upper arm 20 is in an upright
position as shown in Fig. l and the back side 26 of the
robot upper arm 20 extends in a plane including the
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straight line. Moreover, as best shown in Fig. 3
showing the cross section of the robot upper arm 20, a
recess 28 is formed in the backside 26 of the robot
upper arm 20 and the electric cables 40 are extended in
the recess 28. Naturally, pipes may be extended in
addition to the electric cables in the recess 28. The
recess 28 is covered with a suitable cover 42 to protect
and cover the electric cables 40. As stated above, the
electric cables 40 are passed into the robot body lO,
are fastened to the back side of the pedestal 12 with a
suitable cable clamp 44, are passed into the cylindrical
lower end 22 of the robot upper arm 20 through an
opening 22a, are fastened again to the cylindrical lower
end 22 at an upper opening 22b with a cable clamp 44,
and are extended along the straight line connecting the
W-axis and the U-axis to the upper end 24 of the robot
upper arm 20. In the cylindrical lower end 22, the
cabIes 40 pass across or near the W-axis. Accordingly,
the electric cables 40 are not exposed to causes of
damage and breakage, such as bending and stretching,
when the robot upper arm 20 swings about the W-axis, ~ -
because the electric cables 40 are extended along the
straight line. Thus, the electric cables 40 are kept
safe and protected. Furthermore, since the electric
cables 40 are extended along and lie in the back side 26
` of the robot upper arm 20, namely, since the electric
cables 40 are extended externally of the robot assembly,
`~ the electric cables 40 are readily accessible when
assembling the robot assembly or when carrying out
maintenance ser~ice, simply by removing~the cover 42, so
that the electric cables 40 can very easily be extended
on and removed from the robot assembly.
As apparent from the foregoing description, in a
multi-articulated industrial robot according to the
present invention, the electric cables can be extended
along a straight line connecting the center of swing
motion of the robot upper arm and the center of an
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up-down turning motion of the robot forearm on the back
side of the robot upper arm of the robot assembly.
Therefore, the electric cables are not subjected to
causes of damage and breakage, such as bending and
stretching, the electric cables are readily accessible
when asse~bling the robot assembly and when carrying out
maintenance service, and the electric cables are rarely
damaged or broken.
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