Rotatable shuttle transfer unit

A rotatable shuttle transfer unit for transferring a workpiece from a first work station to a second work station along a predetermined path of travel wherein a pair of spaced carriages carry the workpiece along the predetermined path of travel and rotate the workpiece from a first angular orientation to a second angular orientation with respect to an axis of rotation. Preferably, the carriages rotate the workpiece while carrying the workpiece along the predetermined path of travel. The carriages are transported along a guiderail which extends between the first and second work stations. A continuous drive belt reciprocally drives the carriages along the guiderail wherein the continuous drive belt extends from one end of the guiderail to the opposite end of the guiderail. A vertical lift portion reciprocally moves the workpiece in a direction substantially normal to the predetermined path of travel. In addition, the carriages provide releasable power clamps for engaging and securing the workpiece.

FIELD OF THE INVENTION 
The present invention relates to the transferring of a workpiece between 
work stations, and more particularly, to a shuttle transfer unit that 
carries and rotates the workpiece along a predetermined path of travel 
between a first work station and a second work station. 
BACKGROUND OF THE INVENTION 
Generally, shuttle transfer units, of the general type of which the present 
invention is concerned, typically include a fixed frame spanning across a 
plurality of work stations. The shuttle transfer unit transports a 
workpiece between work stations, and each work station typically performs 
some type of manufacturing or assembly process on the workpiece. 
When these shuttle transfer units load and unload the workpiece to and from 
the work stations, the workpiece must be orientated in a proper manner to 
allow for the proper fixturing and processing of the workpiece in the 
associated work station. This can become a rather difficult task when the 
workpieces have rather large and irregular geometries, such as motor 
vehicle chassis and frames. 
Often, such motor vehicle frames and chassis must be rotated or rolled over 
180.degree. such that both sides of the chassis or frames may be made 
accessible for various types of machining and welding processes. 
Currently, due to the size and shapes of such workpieces, the workpieces 
are typically re-orientated or rotated at a separate work station. The 
workpieces are then transported to a subsequent work station wherein the 
workpieces are fixtured for subsequent sequential processing of the 
workpiece. Such handling of the workpiece requires the additional space, 
equipment and time required for simply re-orientating the workpiece with 
respect to the production line. In addition, each work station requires 
the workpiece to be clamped or fixtured, thus requiring new datums and 
references to be established and thereby increasing the range of 
tolerances. Obviously, such processing breeds inefficiencies and is 
undesirable in a production environment. 
It would be desirable to provide a shuttle transfer unit that re-orientates 
a large, irregular workpiece, such as a motor vehicle chassis or frame, 
while transferring the workpiece from one work station to a subsequent 
work station without requiring the need for a separate and additional work 
station for re-orientating the workpiece. 
SUMMARY OF THE INVENTION 
The present invention provides a rotatable shuttle transfer unit for 
transferring a workpiece from a first work station to a second work 
station along a predetermined path of travel wherein a carriage means 
carries the workpiece along the predetermined path of travel and rotates 
the workpiece from a first angular orientation to a second angular 
orientation with respect to an axis of rotation. Preferably, the carriage 
means rotates the workpiece while carrying the workpiece along the 
predetermined path of travel. 
The shuttle transfer unit also provides a means for transporting the 
carriage means along a guiderail which extends between the first work 
station and the second work station. An endless belt means reciprocally 
drives the carriage means in guided movement along the guiderail. The 
endless belt means extends from one end of the guiderail means to an 
opposite end of the guiderail means and is connected to the carriage 
means. A power driving means, which is mounted to the guiderail and 
coupled to the endless belt means, drives the endless belt means. 
The shuttle transfer unit also provides a means for reciprocally moving the 
workpiece in a direction substantially normal to the predetermined path of 
travel. Preferably, the reciprocal moving means moves in a vertical 
direction so as to provide a vertical lift portion for loading and 
unloading the workpiece to and from the work stations. Thus, the 
predetermined path of travel is preferably linear and horizontal. 
The carriage means of the shuttle transfer unit also provides a means for 
releasably engaging the workpiece. This allows the shuttle transfer unit 
to load and unload the workpiece to and from the work stations. 
Preferably, the releasable engaging means provides a means for releasably 
clamping the workpiece. 
Other objects, advantages and applications of the present invention will 
become apparent to those skilled in the art when the following description 
of the best mode contemplated for practicing the invention is read in 
conjunction with the accompanying drawings.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, the present invention will now be described in 
detail with reference to the preferred embodiment. 
FIGS. 1 and 2 shows a rotatable shuttle transfer unit 10 as described in 
the aforesaid invention. The rotatable shuttle transfer unit 10 provides a 
guiderail means that extends between a first work station 12 and a second 
work station 14 and a carriage means that is movably supported on the 
guiderail means. The carriage means has a means for releasably engaging a 
workpiece 16, such as a motor vehicle frame or chassis. Although the 
present invention is not limited to the workpiece 16 being a motor vehicle 
frame or chassis, it should be noted that the present invention is ideally 
suited for the workpiece 16 to be of a structure similar to a motor 
vehicle frame or chassis. The carriage means is transported along the 
guiderail means such that the workpiece 16 is carried along a 
predetermined path of travel. In addition, the carriage means may provide 
a means for rotating the workpiece 16 from a first angular orientation to 
a second angular orientation with respect to an axis 17 of the workpiece 
16 for rotation thereabout. The rotatable shuttle transfer unit 10 may 
also provide a means for reciprocally moving the workpiece 16 in a 
direction normal to the predetermined path of travel so as to allow for 
the loading and unloading of the workpiece 16 to and from the first and 
second work stations 12, 14. 
To movably support the carriage means between work stations 12, 14, the 
guiderail means may provide an overhead guiderail 18 which extends over 
and between the first and second work stations 12, 14, as seen in FIGS. 
1-4C. The guiderail 18 has a substantially C-shaped cross section 20 
wherein the guiderail 18 provides a substantially vertical member 22 and a 
pair or similar opposing substantially horizontal members 24 extending 
transversely from each end of the vertical member 22. A pair of similar 
running rails 26 extend outwardly from the opposing horizontal members 24. 
The running rails 26 are substantially parallel to the vertical member 22 
and extend the entire length of the guiderail 18. 
In order for the rotatable shuttle transfer unit 10 to transfer the 
workpiece 16 from the first work station 12 to the second work station 14, 
the carriage means provides a pair of substantially similar carriages 28, 
30 movably supported and guided by the guiderail 18 for reciprocal 
movement along the guiderail 18. Each of the carriages 28, 30 provides a 
substantially similar frame 32 for supporting the carriages 28, 30 on the 
guiderail 18. The frame 32 of the carriages 28, 30 includes a carriage 
plate 34 that spans across the width of the guiderail 18. A plurality of 
roller assemblies 36 are provided at opposite ends of the carriage plate 
34 to engage the running rails 26 and guide the carriages 28, 30 for 
horizontal movement along the guiderail 18. Preferably, each of the 
carriages 28, 30 provides three equally spaced roller assemblies 36 at 
each of the opposite ends of each carriage plate 34. As seen in FIG. 5, a 
shock absorbing means having a pair of similar shock absorbers 38 mounted 
at each end of the guiderail 18 may be utilized to absorb kinetic energy 
from the moving carriages 28, 30 should the carriages 28, 30 extend in an 
over travel position and approach the ends of the guiderail 18. 
As seen in FIGS. 1-2, the carriages 28, 30 are spaced at a predetermined 
distance along the guiderail 18. A means for adjusting the distance 
between the carriages 28, 30 on the guiderail 18 is provided by a linear 
adjustment carriage 40 spaced between the two carriages 28, 30. The linear 
adjustment carriage 40 is movably supported and guided on the guiderail 18 
in a manner similar to the two carriages 28, 30, wherein three equally 
spaced roller assemblies 42 are mounted at each of the opposite ends of 
the carriage plate 44 of the linear adjustment carriage 40. 
The linear adjustment carriage 40 has a fixed bar 46 having a hollow 
rectangular cross section with one of its ends connected to the linear 
adjustment carriage 40 and its other end connected to one of the two 
carriages 28, 30. The opposite end of the linear adjustment carriage 40 
has a worm gear or screw 48 extending outward from the linear adjustment 
carriage 40 and substantially parallel to the guiderail 18 wherein the 
screw 48 is received by a threaded engagement 50 in the frame 32 of the 
other of the two carriages 28, 30. A reversible motor 52 is provided on 
the linear adjustment carriage 40, and the reversible motor 52 may rotate 
the screw 48 in either direction so as to increase or decrease the linear 
distance between the two carriages 28, 30 along the guiderail 18. The 
linear distance between the two carriages 28, 30 may require adjustment 
when different shape and size workpieces 16 are processed by the shuttle 
transfer unit 10. 
In order to drive the carriages 28, 30 along the guiderail 18, the endless 
belt means provides a continuous drive belt 54 which extends from one end 
of the guiderail 18 to an opposite end of the guiderail 18. As seen in 
FIG. 5, a sprocket 56 is mounted at each end (only one end shown) of the 
guiderail 18 such that the drive belt 54 has an upper and lower portion 
58, 60, respectively, extending between and substantially parallel to the 
horizontal members 24 of the guiderail 18. A reversible drive 62 powers 
rotation of the sprockets 56 and thus drives rotation of the drive belt 54 
in either direction. At least one of the two carriages 28, 30 has its 
associated frame 32 connected to an upper or lower portion 58, 60 of the 
drive belt 54. In the preferred embodiment, only one of the carriages 28, 
30 has a drive belt mount 64 which extends outward from the carriage plate 
34 and is connected to the lower portion 60 of the continuous drive belt 
54, as seen in FIG. 3. 
To lift and lower the workpiece 16 to and from the work stations 12, 14, 
the reciprocal moving means moves the workpiece 16 in a direction 
substantially normal to the predetermined path of travel. Preferably, the 
predetermined path of travel is substantially horizontal and substantially 
parallel to the guiderail 18, and thus, the reciprocal moving means 
provides vertical movement that is substantially normal to the 
predetermined path of travel. As seen in FIGS. 1-3, the reciprocal moving 
means provides a vertical lift portion 66 wherein the frame 32 of the 
carriage 28, 30 supports a pair of substantially parallel and opposing 
running rails 68 connected to the carriage plate 34 and extending away 
from the guiderail 18. An elongate substantially U-shaped portion 70 
provides rollers 72 extending laterally from its ends wherein the rollers 
72 are supported in tracks of the running rails 68 to allow for the 
U-shaped portion 70 to roll or slide vertically along the running rails 
68. 
In order to power vertical reciprocal movement of the U-shaped portion 70 
along the running rails 68, the vertical lift portion 66 provides a 
reversible motor 74 and a series of pulleys 76 to lift and lower the 
U-shaped portion 70. The motor 74 is attached to the frame 32 of the 
carriage 28, 30, and the series of three staggered pulleys 76 extend 
outward from the motor 74. A timing belt 78 is connected to a top portion 
of the U-shaped portion 70, and the timing belt 78 is weaved through the 
series of pulleys 76 and connected to a bottom portion of the U-shaped 
portion 70. The motor 74 drives the pulleys 76 which in turn feed the 
timing belt 78 through the pulleys 76 to provide for the vertical 
reciprocal movement of the U-shaped portion 70. 
The vertical lift portion 66 of each of the carriages 28, 30 has a 
substantially trapezoidal shaped bracket 80 connected to the lower end of 
the U-shaped portion 70. Each of the trapezoidal brackets 80 extend 
vertically downward and have a small housing 82 mounted to the bottom of 
the trapezoidal bracket 80. The small housings 82 provide for rotational 
support of a releasable engagement means for engaging the workpiece 16. As 
seen in FIGS. 1, 3, and 6, the releasable engagement means provides a 
linear elongate bar 84 with an axle shaft 86 integral with and extending 
substantially normal from the elongate bar 84. The axle shaft 86 is 
received and rotatably supported by the housing 82 for rotation about the 
longitudinal axis of the axle shaft 86. The elongate bar 84 has a 
releasable clamping means mounted at each end of the elongate bar 84. Each 
of the releasable clamping means provides a pair of power actuated clamps 
87 with opposing clamping arms 88 that are pneumatically power driven 
between a closed or clamped position and an open or unclamped position. To 
open or move to the unclamped position, the clamping arms 88 pivot and 
rotate outwardly away from the workpiece 16 so that the clamping arms 88 
clear the workpiece 16 when the workpiece 16 is unloaded into the work 
station 12, 14 and the clamping arms 88 are lifted by the vertical lifting 
portion 66. It should be noted that the present invention is not limited 
to the specific structure of the clamps 87 as defined, but rather, the 
present invention may include any structure or clamp adapted for the 
particular structure of the workpiece 16. 
In order to rotate the workpiece 16, a reversible motor 90 is connected to 
the small housing 82, and the reversible motor 90 cooperatively engages 
the axle shaft 86 in which the elongate bar 84 is connected thereto. The 
power actuated clamps 87 are mounted to the elongate bar 84, and thus, 
when the workpiece 16 is clamped by the clamping arms 88, the motor 90 
rotates the workpiece 16 about the longitudinal axis 17 of the shaft 86. 
Preferably, the axis 17 of the workpiece 16 is coaxially aligned with the 
longitudinal axis 17 of the axle shaft 86, and thus, the workpiece 16 is 
rotated from a first angular orientation to a second angular orientation 
with respect to the axis 17. In the preferred embodiment, the workpiece 16 
is rotated 180.degree. between the first and second angular orientations 
with respect to the axis 17 of rotation. 
In operation, the clamping arms 88 of the rotatable shuttle transfer unit 
10 releasably engage the workpiece 16 at the first work station 12. The 
vertical lift portion 66 lifts the workpiece 16 from the first work 
station 12 towards the guiderail 16 without rotating the workpiece 16, as 
seen in FIG. 4C. The continuous drive belt 84 drives both carriages 28, 30 
along the guiderail 16 or predetermined path of travel while the 
reversible motor 90 rotates the workpiece 16 1800 about the axis 17 of 
rotation, as seen in FIG. 4B. Once the carriages 28, 30 have reached the 
end of the predetermined path of travel and the workpiece 16 has completed 
its rotational movement, as seen in FIG. 4C, the vertical lift portion 66 
lowers the workpiece 16 into the second work station 18. The releasable 
clamps 87 release the workpiece 16, and the vertical lift portion 66 lifts 
the releasable engaging means away from the second work station 14 toward 
the guiderail 16, wherein the carriages 28, 30 return to the first work 
station 12 to sequentially engage a subsequent workpiece. 
It should be noted that the invention is not limited to the workpiece 16 
being rotated while moving along the predetermined path of travel, but 
rather, the present invention may include the workpiece 16 rotating and 
moving along the predetermined path of travel sequentially, or in other 
words, at different times. In addition, the vertical lift portion 66 may 
also lift and lower the workpiece 16 while the workpiece 16 is rotating 
and moving between work stations 12, 14. 
While the invention has been described in connection with what is presently 
considered to be the most practical and preferred embodiment, it is to be 
understood that the invention is not to be limited to the disclosed 
embodiments but, on the contrary, is intended to cover various 
modifications and equivalent arrangements included within the sphere and 
scope of the appended claims, which scope is to be accorded the broadest 
interpretation so as to encompass all such modifications and equivalent 
structures as is permitted under the law.