Robotic assembly apparatus with robot tool for placing a plurality of component parts on a workpiece

A robotic assembly apparatus includes a robot (2), a component supply station (6) and at least one placement station (7, 8). Components are correctly orientated by means of feeder bowls (11, 12) and are serially presented to the supply station along tracks (9 and 10). A multi-head tool (5) simultaneously picks up a plurality of correctly orientated components and places them in their correct positions in or on the workpiece. Before or during their travel to the workpiece, the plurality of components are placed in their correct positions relative to one another. Preferably two placement stations are used per robot so that one can be used for removing an assembled workpiece and supplying a new workpiece while the other is having components inserted. The multi-head tool (5) consists of individually-pneumatically-operable actuators (27) carrying individual-operable component grippers which may be mechanical, vacuum or electromagnetic.

CROSS REFERENCE TO RELATED APPLICATION 
This application claims priority under the International Convention for the 
Protection of Industrial Property, from European patent application 
Application No. 86303188.6, filed Apr. 28, 1986 in the European Patent 
Office. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a robotic assembly apparatus having a robot tool 
for placing a plurality of component parts on a workpiece. The invention 
is more particularly concerned with a robot tool which allows a plurality 
of similar parts to be placed simultaneously onto a receiving workpiece in 
a pattern which may vary in accordance with the particular workpiece. 
The invention may advantageously be used in the robotic manufacture of 
keyboards where keypads, keybuttons or key springs need to be placed on or 
in a keyboard frame, the pitch between the key buttons etc being dependent 
upon the particular model of keyboard being manufactured. 
2. Description of the Prior Art 
In recent year, robots have been increasingly used in automated assembly 
operations to perform repetitious and generally tedious work. Typically 
the robot will be presented with a series of workpieces onto or into each 
of which must be placed a number of components or parts. In its simplest 
form, the robotic assembly apparatus would serve to place a single type of 
component part into or onto a single type of workpiece. In a more 
sophisticated version, a number of robotic assembly apparatus might be 
served by a single robot but with each robotic assembly apparatus being 
used to place a single type of component part into or onto a single type 
of workpiece. 
A more flexible arrangement would allow a robot assembly apparatus to deal 
with a plurality of different types of workpiece with different component 
parts, a manual, semi-automatic or fully automatic system being used to 
identify the type (and orientation) of the workpieces and the type (and 
orientation) of the component parts to be placed therein or thereon. 
However for maximum benefit a fully automatic system would be required and 
this in turn implies the need for a complicated and expensive logic and 
recognition system which may have a consequential detrimental impact on 
the reliability and serviceability of the equipment. The means by which 
workpieces and components are correctly orientated and positioned would 
also be complicated. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a robotic assembly 
apparatus and robot tool which allow a plurality of similar parts to be 
placed simultaneously onto or into a workpiece at positions which may vary 
with the type of workpiece. 
According to the invention, a robotic assembly apparatus having a robot 
tool for placing components in or on a workpiece comprises means for 
presenting workpieces serially to a placement station, means for 
presenting components to be placed in or on said workpieces to a supply 
station, and means for picking up components from said supply station and 
placing them into or onto a workpiece at said placement station, 
characterized in that said apparatus further includes means for placing a 
plurality of components in a predetermined pattern and orientation 
relative to one another at said supply station, means for simultaneously 
picking up said orientated plurality of components, means for placing said 
plurality of components into their correct positions relative to one 
another, and means for simultaneously placing the plurality of correctly 
positioned components into or onto said workpiece at said placement 
station. 
In one embodiment of the invention, means is provided for correctly 
positioning said components relative to one another at said supply 
station. 
In a second embodiment, the components are correctly positioned relative to 
one another after they have been picked up during their transport to the 
placement station. 
To speed up operation, more than one placement station may be provided, 
each having its own supply of workpieces. Similarly more than one 
component supply station may be provided. 
Where the number of components to be placed in or on a workpiece exceeds 
the number of components which can be simultaneously picked up, the 
operation is repeated until all the desired positions on the workpiece 
have been filled. Preferably, the number of components which can be picked 
up at any one time is varied by using a matrix of component lifting heads, 
each of which is individually operable under program control.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1, a robotic assembly apparatus --generally indicated 
at 1 in plan view--consists of a robot 2, for example an IBM 7545 robot, 
having arms 3 and 4 by means of which a multi-head gripping tool 5 can be 
moved from the position shown over a component supply station 6 to either 
of two component placement stations 7 and 8. Component parts are fed 
serially to the station 6 along linear feeders 9 and 10 in their correct 
orientation. The feeders 9 and 10 are supplied in turn from vibrating bowl 
feeders 11 and 12 respectively. Vibrating bowl feeders are known, per se, 
and will not be further described: their purpose is to present to the 
linear feeders 9 and 10 component parts correctly orientated. Specially 
shaped channels 13 and 14 in the bowl feeders ensure that only 
correctly-orientated components reach the linear feeders 9 and 10. 
Although in the particular embodiment being described, all the component 
parts are identical, it will be apparent that each bowl feeder may be 
loaded with parts which are unique to that feeder. In this way a number of 
different parts can be presented to the supply station 6. Clearly there 
will need to be at least one supply feeder (9, 10) for each of the 
different component parts. 
Workpieces are carried or presented to the placement stations 7 and 8 on 
shuttles 15 and 16 respectively along tracks 17 and 18 respectively. The 
arrangement is normally such that whilst a workpiece on one of the 
shuttles is having component parts loaded thereon at one placement 
station, the other shuttle is removing a "completed" workpiece from the 
other placement station and presenting a new workpiece. This maximizes the 
operation of the robot 2 which need not spend time waiting for workpieces 
to be loaded or unloaded which would be the case if only one placement 
station were used. 
FIG. 2 is a schematic showing, in plan view, a keyboard frame 19 (which in 
use would be carried to the placement positions 7 an 8 on the shuttles 15 
and 16) having sites on which keybuttons/keybutton parts are to be 
located/inserted. It will be seen that although the sites are generally in 
a matrix, the pitch of the matrix, i.e., the spacings between the 
keybuttons, is not constant and may vary from model to model of keyboard. 
The problem is to ensure that each site is populated with the correct 
component (in the correct position and orientation) in a timely fashion, 
it not being economic to use the robot to place these parts one at a time. 
Correct orientation of the component parts is ensured by use of the 
vibrating feeder bowls 11 and 12, positioning of a plurality of parts 
simultaneously is ensured by the use of the multi-head gripper tool 5 and 
correct positioning of the component parts is ensured by ensuring that 
their positions relative to one another is correct as will be described 
below. 
FIGS. 3 and 4 are plan and side views of the embodiment of the invention in 
which the component parts are correctly positioned relative to one another 
at the component supply station 6. As will be recalled from FIG. 1, the 
components are presented to the station serially in two rows. 
Although the spacing between the two tracks 9 and 10 may be arranged to 
position the components in their correct relative positions in the one 
direction, in the other orthogonal direction the components will be 
abutting on another. In the particular arrangement to be described, the 
component parts to be inserted in the keyboard frame are keypad 
assemblies, each consisting of a plastic pad with a dependent coil spring 
(and shown in FIG. 8, reference numerals 37, 39). 
Thus the keypads are presented to the supply station along the tracks 9 and 
10 which may then converge or diverge into tracks 20 and 21 whose 
separation is equal to the desired separation of the components. 
Positioning in the other (orthogonal) direction is performed by a sliding 
spreader table 22 located beneath the track sections 20 and 21. The 
spreader table has slots or grooves 23 which fan out from the initial 
"end-to-end" spacing of the dependent springs to the desired spacing. As 
the spreader table 22 is moved in the direction of arrow 24 beneath the 
track sections 20 and 21, the slots 23 will engage with the dependent 
springs on the keypads and will cause the pads to separate and spread 
along the tracks to the desired spacing (depending on the pitch P of the 
grooves or slots 23). 
After pick-up of the separated components, the spreader table is withdrawn 
allowing the next batch of parts to be presented along the tracks 9 and 10 
to the track sections 20 and 21. Sensors 25, shown schematically, beneath 
the track sections 20 and 21 sense for the presence or absence of springs 
(and hence components) before and after pick-up. As will be described 
later, the multi-head tool would normally pick up twelve component parts 
but it can be programmed to pick up any number from 1 to 12 to allow for 
variations in the pitch of the component positions of the workpiece 19. 
What has been described is a mechanism that allows component parts to be 
orientated and correctly positioned relative to one another for 
simultaneous placement on a workpiece. 
The number of parts to be placed at any one time is a function of the 
number of parts that can be arranged in the correctly positioned and 
orientated condition and the proportion of those actually picked-up by the 
multi-head tool 5 or released thereby. FIG. 5 is a schematic of the 
multi-head tool which, in the embodiment, shown includes twelve grippers 
26 arranged in two rows of six each. As shown in FIG. 5, in which six 
grippers are shown retracted and six extended, each gripper mechanism is 
separately movable in the vertical direction. Moreover, each gripper can 
be separately operated so as to grip or release its associated component 
part. Any suitable gripping mechanism can be used, mechanical, vacuum or 
electromagnetic depending on the size, nature and weight of the 
components. Generally the pitch of the matrix of grippers will correspond 
to the pitch of the component positions on the workpiece. In some 
instances it may be possible to use a gripper construction/technology 
which allows for a variation in the "workpiece pitch." 
FIGS. 6 to 8 are drawings of a pneumatically operated gripper mechanism 5 
employing mechanical grippers 26. As is shown in FIG. 6, each gripper 26 
is carried as an actuator 27 having a bore 28. Each actuator 27 can be 
moved vertically and independently of the other actuators by pneumatic 
operation of the piston 29 within cylinder 30. In addition to the vertical 
movement produced by individual movement of the actuator 27, the whole of 
the assembly 5 is also movable vertically. 
Operation of the gripper mechanism 26 can be seen with reference to FIGS. 7 
and 8 which shown, respectively, the open and closed positions of a 
pivotable, gripper jaw 31, opened under the action of a push rod 32, 
connected to a piston 33 within a cylinder 34, against a return spring 35. 
A notch 36 on the gripper jaw 31 engages, in the closed position, the edge 
of the spring pad 37 which is urged against surface 38. Also shown in FIG. 
8 is the dependent spring 39 of the spring pad assembly (and which are 
used by the slots or grooves 23 of the spreader table 22, FIG. 3, to 
spread the spring pad assembly to the desired spacing). 
The invention is not limited to the use of mechanical grippers and as 
mentioned above, any suitable technique such as vacuum or electromagnetic 
may be used. FIGS. 9 and 10 show an embodiment of the invention in which 
the grippers 26 are vacuum holders. To this end the undersides of the 
grippers are shaped to correspond to keybuttons 40 to be placed on a 
workpiece. In this case the bores of the actuators 27 are individually and 
controllably connected to a source of vacuum. As in the case of the 
arrangement shown in FIGS. 6 to 8, each actuator 27 is individually 
movable in a substantially vertical direction as is the whole assembly 5. 
FIG. 9 also serves to illustrate another technique for separating the 
component parts to desired spacings and which can be used instead of or as 
well as the spreader table 22 of FIG. 3. As will be seen in FIG. 9, the 
cylinders 30 (and actuators 27) are angled with respect to one another. As 
the actuators 27 are moved down, their tips and grippers 26 will separate 
from one another. The amount of separation will depend upon the angles 
between the cylinders 30 and actuators 27 and the stroke. In a typical 
keyboard application, relative angles between the cylinders of 7.degree. 
mm to 8.degree. mm with a stroke between 2 and 4 cm are generally adequate 
to accommodate the different pitch requirements. 
What has been described is a relatively inexpensive but flexible robotic 
assembly apparatus employing a robotic tool which enables a plurality of 
similar components or parts to be simultaneously placed upon a workpiece 
in their correct orientations and positions. Because the tool is 
programmable, it is able to execute a number of insertions at different 
locations from a single pick-up cycle. The robotic assembly apparatus is 
flexible and relatively uncomplicated but without being constrained to 
place components one by one on the workpieces. 
Without major modification, a number of different types of component can be 
assembled at the robotic assembly apparatus by presenting the components 
at the supply station in their correct groups and orientations and 
thereafter selectively releasing the different parts at the workpiece. 
Simple programming of the robot and multihead tool allows for different 
workpieces. Although the invention has been described with reference to 
keyboard assembly, its principles are clearly applicable to other assembly 
operations where a plurality of similar parts need to be inserted in or at 
pre-defined positions on a workpiece, for example populating printed 
circuit boards.