Industrial robot

An industrial robot is constituted by a plurality of series connected arm units each composed of a driving unit from among a plurality of driving units having different driving powers and different driving speeds, a joint unit from among a plurality of joint units having different driving speeds and power transmitting capacities, and an arm from among a plurality of arms having different sizes and load capacities. The joint units, driving units and arms each have connecting surfaces thereon having positioning parts and setting-fixing parts in a predetermined pattern for enabling the joint units, driving units and arms to be detachably connected to other joint units, driving units and arms at corresponding connecting surfaces to form arm units with the desired joint units, driving units and arms. The joint units each have a stationary frame and a follower frame rotatably connected to each other and driving power transmitting mechanism connected between said frames and including reduction gears. The driving units each have a motor and an output member fixed to the motor shaft which, when a driving unit is connected with a joint unit, is engaged with power transmitting mechanism.

DESCRIPTION 
1. Technical Field 
The present invention primarily relates to a multi-joint robot for 
industrial use applicable to operations of assembling and adjustment of 
machine parts. 
2. Background Art 
The conventional type multi-joint robot has been subject to limitation as 
to the spatial range of operation since the arms thereof are driven by 
actuators disposed near the base through rings or the like, and has 
difficulties in operation in a narrow space because of actuators and other 
elements extending into the space outside the joints. 
A joint part or a joint part connected to an arm part has been a solid 
structure and incapable of meeting the requirements of wider range of 
operation. Also, when required to carry a heavier load, the robot of this 
type has had the a problem of insufficient output and of being incapable 
of easily satisfying the requirement for increasing the work transfer 
speed. As described above, the conventional type multi-joint industrial 
robot has had drawbacks such as incapability of corresponding to variation 
in operation space, limitations on the weight of the work, and work 
transfer speed. 
As a device for eliminating the above-described drawbacks, there is, for 
example, a robot constructed of the so-called building block system 
composed of standarized units each having interchangeability with the 
others and combined for use like building blocks. 
This type of robot includes a plurality of standardized units each 
comprising a base, components movable relatively to the base, driving 
means for driving these components, and sensing means for sensing relative 
positions of the base and the movable components and differing from the 
others in driving power, spatial operation range, etc., and suitably 
combined with the other according to the use thereof, thereby being 
characterized by adaptability to varieties of operation. 
However, such structure as above permits no more than selective combination 
of units with the aid of standarized shapes and sizes of parts of the base 
and movable components, and each unit lacks versatility and adaptability 
to variation in operation space, moving speed, and driving power. 
Therefore, when, for example, driving power is desired to be varied while 
the operation space is kept the same, the unit itself must be replaced by 
another one, thereby preventing performance helpful to cost saving or 
operation. 
DISCLOSURE OF THE INVENTION 
An object of the present invention is to provide a structure particularly 
suitable for the joint-type robot and adaptable to a variety of 
operational conditions including operation space, loading capacity, work 
transfer speed, and so on, to overcome the problems as described above and 
to provide a structural and mounting arrangement of joint parts, arms, and 
driving means, wherein an actuator incorporated into the arm and reduction 
gears disposed in the joint part make it possible to provide slim arms and 
small-sized joint parts, greatly contributing to automation of assemblage 
and adjustment operation, which type of apparatus is in strong demand 
these days. 
The present invention is characterized by a structure to achieve the above 
object which is provided with a base unit turntable around a vertical axis 
and a plurality of arm units to be connected to each other in series and 
disposed on the turning base, each arm unit comprising driving units of a 
plurality of kinds corresponding to the variety of driving power 
transmitting capacity, and arms incorporating driving units thereinto, 
capable of being connected to joint units at both ends thereof, and of a 
plurality of kinds for corresponding to the variety of operation space and 
loading capacity, which are all selectively combined and connected to each 
other. Further, the present invention is characterized in that the driving 
unit is detachably connected to the joint unit which is also detachably 
connected to the arm through a key. Still further, the present invention 
is characterized by a driving unit comprising a motor provided with a 
driving power transmitting member on the output shaft thereof, a flange to 
which an encoder, potentiometer, and brake are integrally secured, and 
bearing parts arranged within the flange so as to rotatably retain the 
output shaft of the motor. 
Furthermore, the present invention is characterized in that a joint unit is 
composed of two joint members approximately U-shaped and rotatably 
connected to each other, one set of bearing disposed at each of two 
connecting parts of the abovesaid members, reduction gears provided on one 
or both of the abovesaid connecting parts, and adjusting members which are 
capable of adjusting the gap between connecting parts and variable in the 
direction of the axis of the joint member, disposed on two connecting 
parts of one joint member.

MOST PREFERRED EMBODIMENT OF THE INVENTION 
As shown in FIGS. 1a and 1b and FIG. 2, and industrial robot according to 
the present invention comprises a plurality of arm units 1, 2, and 3 
connected to each other in series and disposed on the base unit A. The 
base unit A comprises a turning table b disposed on the base a and driven 
around a vertical axis B through the motor and reduction gears (both not 
illustrated), arm units 1, 2, and 3 being each composed of an arm C, 
driving unit D, and joint unit E. The arm C is hollow and, at one end, is 
detachably connected to the flange 17 on the stationary frame 17a joint 
unit E by bolts 6 through the flange 4 and a key 5 and is detachably 
connected to another joint unit 8 at the other end through the key 7. The 
driving unit D is disposed in the hollow interior of arm C and detachably 
connected into the joint unit E with bolts 9 at the outer periphery of the 
flange 4. 
FIG. 3 shows an example of selective combination of an arm C.sub.1 or 
C.sub.2 and the joint unit E. FIG. 3a is a plan of the flange 17 of the 
stationary frame of the joint unit E, in which keyways 5a, a recess 4a to 
receive a flange 4 of a drive unit C.sub.1 or C.sub.2, and threaded holes 
6a for bolts are provided in a plurality of patterns in accordance with a 
predetermined arrangement. FIGS. 3b and 3c are plan views of the end face 
of arms C.sub.1 and C.sub.2, respectively, in which keyways 5b, an 
aperture 4b to receive a flange 4, and holes 6b for bolts 6 are formed in 
one of the patterns in accordance with the predetermined arrangement. 
Before the arc C.sub.1 or C.sub.2 is connected to the joint E by bolts 6 
inserted through holes 6a or 6b and fastened, keys 5 are inserted into 
keyways 5a and 5b and the flange 4 on a driving unit is fitted into recess 
4a and connected to joint unit E. As already apparent, so long as recess 
4a, flange 4b, keyways 5a and 5b as well as bolt holes 6a and 6b are 
formed in accordance with a predetermined arrangment, either the arm 
C.sub.1 or the arm C.sub.2 can be connected to joint unit E. 
Similarly, the joint unit E and the driving unit D are formed so as to be 
selectively combinable. 
Incidentally, a key is described as being used for a positioning part; 
however, a pin may be used instead. After all and as a matter of course, 
the purpose is fulfilled by fixing the position of the arm relatively to 
the joint unit as predetermined as well as of the joint unit relatively to 
the driving unit. 
The driving unit is constituted by the flange 4 having integrally secured 
thereto a motor 12 having a bevel gear 11 fixed to the output shaft 
thereof through the key 10, a position sensing unit 13 into which an 
encoder and potentiometer are integrally incorporated, and a brake 14 
which operates when the power supply for the motor is cut, bearings 15 and 
16 incorporated into the flange 4 supporting against a bending force and 
an axially acting force produced at the bevel gear. On the joint unit E, 
an approximately U-shaped stationary frame 17a constituting a joint member 
has a follower frame 18 supported thereon by bearings 19 and 20 for 
rotation around the axis F of a rotating shaft 24, the gaps between 
bearings and adjoining members being adjusted by collars 21 and 22 
disposed in a first step in flange 17 and the power transmitted from the 
driving unit D is further transmitted to the shaft 24 through bevel gears 
11 and 23, whereby the stationary and the follower frames 17 and 18, 
respectively, perform relative movement for bending the joint unit with 
high precision through reduction gears 25 and 26. The main shaft 24 is 
supported by bearings 27, 28, 29, and 30 in the stationary and the 
follower frames 17 and 18, respectively, and gaps between these bearings 
and adjoining members can be adjusted by fastening nuts 31 and 32 disposed 
at both ends of the main shaft for preventing backlash in the axial 
direction. Power transmission between the driving unit D and the joint 
unit E can be made smooth and free from backlash by adjusting and then 
fixing gaps between teeth of bevel gears 11 and 23 at a certain width. The 
force acting in the axial direction in the main shaft 24 produced by the 
abovesaid bevel gear 23 or reduction gears 25 and 26 is supported by 
thrust bearings 34 and 35 provided on the main shaft 24. 
As shown in FIG. 4, the reduction gears 25 and 26 each comprise an 
elliptical driving wheel 37 fixed to the main shaft 24 through the key 36, 
an externally-toothed elastically deformable gear 38, an 
internally-toothed wheel 39 meshing with the externally-toothed gear 38 at 
two points and fixedly secured to a frame 17a and an internally-toothed 
wheel 40 fixed frame 18, and the internally-toothed wheel 39 having the 
same number of teeth as the externally-toothed wheel 38 whereas the 
internally-toothed wheel 40 has a different number of teeth from those of 
the other two toothed wheels. 
Other joint units have the same structure as described above and can be 
assembled into a multi-joint robot. 
Driving units D, joint units E, and arms C, each having of the structure as 
described above, are prepared in a plurality of forms according to the 
driving power and speed, driving power transmitting capacity, and 
operation space and loading capacity, respectively, and these units can 
selectively combined for forming an arm unit and a plurality of such arms 
units are connected to each other in series to be formed into a robot. 
When the arm length is increased, driving power must be increased due to an 
increased moment; however, the length need not be increased in some cases 
according to the manner of operation even when, for example, the arm is 
elongated for extending the operation space. In the latter case, 
replacement of only the arm with a different one may suffice though the 
joint unit and the driving unit remain unchanged. The arm can be replaced 
without any influence on the connection of the joint unit to the driving 
unit, and connection of the driving unit with the joint unit establishes 
connection for power transmission, too, the connecting operation as well 
as the detaching operation being easy. 
In this embodiment, the rotating axis of the joint is horizontal; however, 
it may be vertical, that is, it is not limited. 
Now, the operation of a robot will be described. 
When the motor rotates in the right or reverse direction, the driving wheel 
37 rotates through bevel wheels 11 and 23 and the main shaft 24. With the 
rotation of the driving wheel 37, the externally-toothed wheel 38 is 
deformed and meshing points thereof with the internally-toothed wheels 39 
and 40 move but the position of the externally-toothed wheel 38 relative 
to the internally-toothed wheel 39 is not varied because of the same 
number of teeth of both wheels. However, the position of the 
externally-toothed wheel 38 relative to the internally-toothed wheel 40 is 
changed due to the different number of teeth between the two wheels and 
the wheel turns the follower frame 18. 
Since the motor 24 is provided with a position sensing unit 13, arm units 
1, 2, and 3 can move to the desired positions. 
INDUSTRIAL APPLICABILITY 
As described above, according to the present invention, a robot is easily 
constructed by forming arm units, each being to be composed of joint 
units, driving units, and arms selectively combined corresponding to the 
kinds of operation space, weight of the work, and work transfer speed, and 
by connecting these units to each other in series. Thus, a multi-joint 
robot operable with high precision is provided and increased versatility 
in the use is ensured. 
In addition, since the arm is hollow and adapted to contain actuators and 
the like therewithin, the mechanism has no projecting parts and, 
therefore, is slim, and the provision of reduction gears for each joint 
permits size reduction in all parts, thereby making it possible to provide 
a multi-joint robot highly effective for operation in a narrow space.