Indexing conveyor for a die transfer system

A die transfer system that includes a lower die, an upper die carried for reciprocal movement toward and away from the lower die to perform at least one operation on a workpiece positioned therebetween, and a conveyor arrangement for sequentially conveying workpieces between the dies. The conveyor arrangement includes a pair of conveyors disposed on laterally opposed sides of the lower die, with each of the conveyors having hands for engaging successive workpieces and indexing the workpieces longitudinally of the lower die between the die stations. At least one of the conveyors is mounted to a fixed support base for selectively swinging such conveyor laterally away from the lower die to afford operator access to such conveyor and the lower die.

The present application is directed to a die transfer system, and more 
particularly to an improved conveyor for indexing workpieces through 
successive stations of the die assembly. 
BACKGROUND AND OBJECTS OF THE INVENTION 
In so-called progressive die systems, workpieces formed from strip stock 
remain attached to webs that extend along lateral edges of the pieces to 
facilitate indexing of the workpieces through successive stages of the die 
assembly. Although such arrangements facilitate conveyance of workpieces 
through the die stations, they possess the disadvantage that the 
workpieces must be formed in a linear array at spaced locations along the 
strip stock, leading to substantial inefficiency and waste. Furthermore, 
the fact that all workpieces remain interconnected during at least a major 
portion of the die operation can lead to difficulty and inefficiency in 
performing operations on the workpieces at a given station. For these 
reasons and others, so-called die transfer systems have been developed in 
which the workpieces are pre-separated and fed to individual units of the 
die arrangement. A die transfer system of this character permits more 
efficient use of the strip stock material, and also permits greater 
flexibility in operations that can be performed at the individual die 
stations. However, the conveyor arrangement for indexing individual 
workpieces through a die transfer system is more complex than those in 
typical progressive die systems, usually involving release and 
re-engagement with the workpieces at each of the individual die stations. 
U.S. Pat. No. 5,136,874, assigned to the assignee hereof, discloses a die 
transfer system that includes a lower die, an upper die carried for 
reciprocal vertical movement toward and away from the lower die to perform 
at least one operation on a workpiece positioned therebetween, and a 
conveyor arrangement for sequentially conveying workpieces between the 
dies. The conveyor arrangement has a pair of conveyors disposed on 
opposite lateral sides of the lower die. Each conveyor includes a 
plurality of hands for gripping workpieces, with the hands being spaced 
from each other lengthwise of the conveyor by distances corresponding to 
stations of the die. Each conveyor and its associated hands are indexed in 
a longitudinal direction through the die between stations in synchronism 
with motion of the upper die. The hands are moved simultaneously in at 
least one direction perpendicular to the longitudinal indexing direction 
by a camshaft that extends through the stations along an axis parallel to 
the indexing direction. A cam is mounted on each camshaft for rotation 
with the camshaft in synchronism with motion of the upper die. A follower 
arrangement couples each cam to the hands of the associated conveyor, so 
that reciprocal rotation of the camshaft about its axis results in 
reciprocal motion of the hands in one or more directions lateral to the 
longitudinal direction of conveyance of workpieces through the die 
stations. The conveyor camshafts are rotated by cam-and-follower 
arrangements coupled to the upper die, or by electric servo motors 
controlled by a master controller. 
Although the die transfer system and indexing conveyor arrangement 
disclosed in the noted patent address and overcome problems and 
deficiencies theretofore extant in the art, further improvements remain 
desirable. For example, it is occasionally desirable to afford operator 
access to the workpiece hands of the conveyor and/or to the forming 
elements of the die either for purposes of maintenance, or for purposes of 
change-over to workpieces of different configuration. A general object of 
the present invention, therefore, is to provide a die transfer system of 
the character described above that features an improved conveyor 
arrangement with facility for providing operator access to the conveyor 
and/or lower die for maintenance, repair and/or change-over purposes and 
the like. Another and more specific object of the present invention is to 
provide a die transfer system of the described character that is 
economical in construction. 
SUMMARY OF THE INVENTION 
A die transfer system in accordance with the present invention includes a 
lower die, an upper die carried for reciprocal movement toward and away 
from the lower die to perform at least one operation on a workpiece 
positioned therebetween, and a conveyor arrangement for sequentially 
conveying workpieces between the dies. The conveyor arrangement includes a 
pair of conveyors disposed on laterally opposed sides of the lower die, 
with each of the conveyors having hands for engaging successive workpieces 
and indexing the workpieces longitudinally of the lower die between the 
die stations. At least one of the conveyors is mounted to a support base 
for selectively swinging such conveyor laterally away from the lower die 
to afford operator access to such conveyor and the lower die. 
In the preferred embodiment of the invention, each conveyor is mounted to 
the support base to pivot about an associated axis parallel to the 
longitudinal indexing direction and above the lower die, so that the 
conveyors may be selectively swung laterally away from and above the lower 
die. Each conveyor swing axis is defined by a shaft carried by the base on 
which the conveyor is mounted. A motor is coupled to the shaft through a 
gear box, and is responsive to an operator for selectively swinging the 
conveyor upwardly away from and downwardly toward the lower die under 
control of the operator.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
FIGS. 1-2 illustrate a die transfer system 10 in accordance with a 
presently preferred embodiment of the invention for indexing workpieces 
through successive stations of a workpiece die. A pair of workpiece 
conveyors 12,14 are positioned on laterally opposed sides of a lower die 
16, and an upper die 18 is carried by a fixed press support base or frame 
20 for vertical reciprocation with respect to lower die 16. In general, 
conveyors 12,14 cooperate with the upper and lower dies to define a 
workpiece load station at the upstream end of the conveyors, an unload 
station at the downstream end of the conveyors, and at least one station 
positioned therebetween at which a desired operation(s) is performed on 
each workpiece upon descent of the upper die. Details of the dies, the 
geometry of the workpieces and of operations performed thereon by the 
dies, are not directly germane to the present invention. 
In general, the constructions of conveyors 12,14 are mirror images of each 
other. Each conveyor 12,14 includes an endless loop conveyor having a belt 
22 trained over a pair of pulleys 24,26 (FIG. 2) spaced from each other in 
the longitudinal direction of workpiece conveyance. Belt 22 is driven by 
an electronic servo motor 28, which in turn is controlled by a motor 
controller. A carriage 30 supports a camshaft 32 that is driven by an 
electric servo motor 34 through a gearbox 36. Camshaft 32 is coupled at 
opposed ends to longitudinally spaced cam arrangements that are enclosed 
by cam housings 38,40. The cams are coupled by carriages 42,44 to a 
transfer bar 46 that extends longitudinally of lower die 16. At least one 
workpiece hand is carried by transfer bar 46, and is coupled to belt 22 by 
a suitable slide and bearing arrangement 50. In general, the hands are 
indexed longitudinally of the conveyor and lower die by operation of servo 
motor 28, and is moved laterally inwardly and outwardly with respect to 
the lower die and the opposing conveyor, and upwardly and downwardly with 
respect to the lower die, by operation of transfer bar 46 and the cams 
within enclosures 38,40. To the extent thus far described, each conveyor 
12,14 is the same as disclosed in above-noted U.S. Pat. No. 5,136,874, the 
disclosure of which is incorporated herein by reference for additional 
details of construction and operation of the conveyors. 
In accordance with the present invention, at least one of the conveyors 
12,14, and preferably both conveyors, is mounted to swing upwardly away 
from lower die 16 so as to afford easier operator access to the lower die 
and conveyors for purposes of maintenance, repair, tool change-over, etc. 
That is, frame 30 and cam enclosures 38,40 of conveyor 12 are affixed to a 
shaft 52. Shaft 52 is rotatably carried at one end by a bearing 54, and at 
the opposing end by a gearbox or transmission 56. Bearing 54 and 
transmission 56 are carried by die base or frame 20 so that shaft 52 is 
rotatable about a fixed axis parallel to the longitudinal direction of 
workpiece conveyance through the die transfer system and parallel to 
camshaft 32, and laterally outwardly and upwardly with respect to lower 
die 16. A motor 58 is carried by base 20 and operatively coupled to 
gearbox 56 for rotating shaft 52. Motor 58 is controlled by suitable swing 
control means 60, which in turn is responsive to an operator switch 62 for 
selectively swinging the conveyor away from or toward the lower die. Motor 
58 may comprise an electric motor, with control 60 and switch 62 being 
suitable electronic control mechanisms. Alternatively, motor 58 may 
comprise an operator controlled hydraulic motor arrangement. Conveyor 14 
is likewise carried by a shaft 52 (FIG. 1) and coupled to a motor 58 for 
swinging conveyor 14 away from or toward lower die 16. 
In operation, when it is desired to repair or replace a workpiece hand 
and/or repair or replace forming elements on the lower or upper die 16,18, 
operation of the press and transfer system is terminated. The operator 
then activates operator switch 62 (FIG. 2) on one or both sides of the 
conveyor, driving the associated motor 58 and rotating the associated 
shaft 52 until the conveyor 12 or 14 is swung up and away from dies 16,18 
by the desired amount. FIG. 1 illustrates an intermediate position 12a and 
a fully raised position 12b for pivoting conveyor 12 around the axis of 
shaft 52. Conveyor 14 may, of course, be pivoted about its shaft 52. In 
this connection, it is preferable that the conveyors be pivotable about 
their respective shafts independently of each other since, for a 
particular repair or replacement operation, it may not be necessary to 
pivot both conveyors by the same amount, or it may not be necessary to 
pivot one of the two conveyors at all. Preferably, each conveyor may be 
locked in any position between the lowered fully operational position 
illustrated in solid lines in FIG. 1, and upper fully retracted position 
12b.