U.S. patent number 3,911,719 [Application Number 05/528,778] was granted by the patent office on 1975-10-14 for high speed ejector mechanism.
This patent grant is currently assigned to Ragsdale Brothers Inc.. Invention is credited to David Degenhardt, Fred Nelson.
United States Patent |
3,911,719 |
Degenhardt , et al. |
October 14, 1975 |
High speed ejector mechanism
Abstract
An ejector mechanism for ejecting a thin-walled seamless
cylindrical metal can having a bottom from around the punch of a
drawing and ironing press having one or more hollow cylindrical
dies and a punch which is movable into said dies to draw and iron a
ductile metal blank or cup into a can. The front end of said
ejector mechanism forms the nosepiece of the punch and said
nosepiece moves reciprocally with respect to said punch after the
punch begins its rearward stroke out of the dies.
Inventors: |
Degenhardt; David (Denver,
CO), Nelson; Fred (Englewood, CO) |
Assignee: |
Ragsdale Brothers Inc.
(Englewood, CO)
|
Family
ID: |
24107153 |
Appl.
No.: |
05/528,778 |
Filed: |
December 2, 1974 |
Current U.S.
Class: |
72/345; 72/427;
72/349 |
Current CPC
Class: |
B21D
45/04 (20130101) |
Current International
Class: |
B21D
45/00 (20060101); B21D 45/04 (20060101); B21D
045/00 (); B21D 045/02 (); B21D 045/04 () |
Field of
Search: |
;72/344,345,349,427
;113/7R,7A,12H |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: DiPalma; Victor A.
Attorney, Agent or Firm: Sloan; Jack C.
Claims
What is claimed is:
1. An ejector mechanism for ejecting a workpiece from a drawing and
ironing press having at least one die, a means adapted for
receiving said workpiece, and a punch mounted to a powered punch
carriage so adapted and arranged that the punch moves in the die(s)
during a forward stroke to draw and iron the workpiece and moves
out of the die(s) during a rearward stroke to permit ejection of
the workpiece from the press, said ejector mechanism
comprising:
a. A nosepiece reciprocally mounted with respect to the working end
of the punch, said nosepiece having a forward working end for
drawing and ironing the workpiece and for ejecting said workpiece
by moving forward with respect to the punch just after the punch
begins its rearward stroke, and having a rear end rigidly attached
to a push rod for transmitting reciprocal motions from the push rod
to said nosepiece;
b. A push rod for transmitting reciprocal motions to the nosepiece
by having one end of said push rod rigidly attached to the
nosepiece and another point fixedly mounted for reciprocation
therewith, to a damping means and by having another point on said
push rod fitted with at least one connector for pivotal connection
with at least one actuator arm and by having another point fitted
with a means for fitting a biasing means which returns the push rod
to a position far enough to the rear that the nosepiece returns to
the working end of the punch after a forward force delivered by the
actuator arm is removed and before the punch carriage completes its
rearward stroke;
c. At least one actuator arm for transmitting forward forces to the
push rod from an actuator arm and for transmitting rearward forces
from the push rod biasing means to the actuator arm by having one
end of the actuator arm pivotally connected to the push rod and the
other end pivotally connected to an actuator;
d. At least one actuator pivotally mounted to the ram carriage at
one end and pivotally mounted to the actuator arm at some point
adjacent to the actuator's punch carriage pivot mounting so that
the actuator pushes the actuator arm forward when the actuator is
forced to pivot forward about the actuator's punch carriage pivot
mounting by a levered pivot action delivered to the actuator by a
trip dog after the punch carriage begins its rearward stroke with
said actuator being so adapted and arranged that it initially jams
against the trip dog to create the levered pivot action of the
actuator about its punch carriage pivot mounting and then slides
past the trip dog when the actuator has pivoted far enough forward
to allow the actuator to slide past the trip dog as the punch
carriage continues on its rearward stroke and then allows the
actuator to slide past the trip dog without creating any levered
pivot action during the forward stroke of the punch carriage;
e. At least one trip dog, having a biasing means to return the trip
dog to an actuating position when the trip dog is not in contact
with the actuator, and having an actuating end so adapted and
arranged that the actuating end initially jams against the actuator
after the punch carriage begins its rearward stroke and then allows
the actuator to slide past the actuating end of the trip dog as the
punch carriage continues on its rearward stroke and then allows the
actuator arm to slide past the biased trip dog without pivoting of
the actuator forward as the punch carriage makes its forward
stroke;
f. A biasing means for returning the push rod to its rearward
position with respect to a damping means after the actuator slides
past the trip dog, but before the punch carriage completes its
return stroke:
g. A damping means mounted to the punch carriage and reciprocally
mounted to the push rod for damping the return of the nosepiece to
the punch during the period the push rod is under the influence of
the biasing means after the actuator slides past the trip dog
during the rearward stroke of the punch carriage.
2. The mechanism of claim 1 wherein the workpiece receiving means
is adapted to receive a blank of material capable of undergoing
drawing and ironing.
3. The mechanism of claim 2 wherein the workpiece receiving means
is adapted to receive a blank of ductile metal.
4. The mechanism of claim 3 wherein the workpiece receiving means
is adapted to receive a blank of aluminum.
5. The mechanism of claim 3 wherein the workpiece receiving means
is adapted to receive a blank of mild steel.
6. An ejector mechanism for ejecting a thin-walled cylindrical
metal can having a bottom from around a ram of a drawing and
ironing press having a means adapted for receiving a ductile metal
blank, a hollow cylindrical die or dies and a punch mounted to a
powered punch carriage so adapted and arranged that a working end
of said punch moves into the die(s) during a forward stroke to draw
and iron the ductile metal blank into a can and moves out of the
die during a rearward stroke to permit ejection of the can, said
ejector mechanism comprising:
a. A nosepiece reciprocally mounted with respect to the working end
of the punch, said nosepiece having a forward working end for
drawing and ironing the can and for ejecting the can from around
the punch by a forward movement with respect to the punch just
after the punch starts the rearward stroke, and having a back end
rigidly attached to a push rod for transmitting reciprocal motions
from the push rod to the nosepiece;
b. A push rod for transmitting reciprocating motions to the
nosepiece by having one end rigidly attached to said nosepiece and
the other end fixedly mounted for reciprocation therewith, to a
damping means with said push rod being fitted with a plurality of
connectors for pivotal connection with a plurality of actuator arms
and being fitted with a biasing means to return said push rod to a
rearward position after forward forces delivered by the actuator
arms are removed and before the punch carriage completes its
rearward stroke;
c. A plurality of actuator arms for tramsmitting forward forces to
the push rod from a plurality of actuators and for transmitting
rearward forces from the push rod biasing means to the actuators by
having each actuator arm pivotally connected to the push rod at one
end and the other end pivotally connected to an actuator which
pushes the actuator arm forward after the punch begins its rearward
stroke;
d. A plurality of actuators, each pivotally mounted to the punch
carriage at one end and each pivotally mounted to an actuator arm
at some point adjacent to the actuator's punch carriage pivot
mounting so that the actuator pushes the actuator arm forward when
the actuator is forced to pivot forward about the actuator's punch
carriage pivot mounting by a lever action delivered to the actuator
by a biased trip dog after the punch carriage begins its rearward
stroke with said actuator being so adapted and arranged that it
initially jams against the trip dog to create the pivot action of
the actuator about its punch carriage pivot mounting then slides
past the trip dog when the actuator has pivoted far enough forward
to allow the actuator to slide past the trip dog as the punch
carriage continues on its rearward stroke and allows the actuator
to slide past the trip dog without creating any lever actions
during the forward stroke of the punch carriage;
e. A plurality of trip dogs, each having a biasing means to return
the trip dog to an actuating position when the trip dog is not in
contact with the actuator, and each having an actuating end so
adapted and arranged that the actuating end initially jams against
the actuator after the punch carriage begins its rearward stroke,
and then allows the actuator to slide past the actuating end of the
trip dog as the actuator pivots forward as the punch carriage
continues its rearward stroke and subsequently allows the actuator
arm to slide past the biased trip dog without forward actuation of
the actuator as the punch carriage makes its forward stroke;
f. A spring resting between the push rod and a spring housing which
forms a fixed part of the punch carriage, for returning the push
rod to a rearward position with respect to the damping means after
the spring has been put in compression by the forward force of the
actuator arm as the actuator jams against the trip dog, with said
spring being allowed to decompress and hence push the push rod
rearward after the actuator slides past the trip dog during the
punch carriage's return stroke, with said spring having sufficient
force to return the push rod to the rearward position before the
punch carriage completes its rearward stroke;
g. A hydraulic damping means fixedly mounted to the ram carriage
and having means for fixedly mounting for reciprocation therewith,
the push rod, for damping the closing of the nosepiece to the punch
during the period when the push rod is under the influence of the
decompressing spring after the actuator has slid past the trip dog
during the rearward stroke of the punch carriage;
7. The ejector mechanism of claim 6 wherein two actuator arms, two
actuators, and two trip dogs are mounted in bilateral symmetry
about the push rod.
8. The ejector mechanism of claim 7 wherein the trip dogs are
mounted so that contact with the actuators is made near the end of
the actuator which is opposite the actuator's punch carriage pivot
mounting and at a time before the actuator has traveled rearward a
distance of less than two inches.
9. The ejector mechanism of claim 8 wherein the means to bias the
trip dogs into the actuating position is air pressure.
10. The ejector mechanism of claim 6 wherein the hydraulic damping
means operates in two stages to allow a first stage for a rapid
initial closing of the distance between the nosepiece and the punch
when the spring is moving the push rod rearward and a slower
closing during a second stage before the nosepiece and the punch
come into actual contact so as to prevent harmful impacts between
said nosepiece and punch.
Description
BACKGROUND OF THE INVENTION
This invention relates to ejector mechanisms for drawing and
ironing presses which conventionally comprise one or more dies and
a punch which is movable coaxially with respect to the dies with
both the dies and the punch each comprising an axially central bore
so adapted and arranged that the ductile material of a blank or cup
flows back in a space between the walls of the punch and the dies
to form a container. More particularly, this invention relates to
ejector mechanisms for drawing and ironing presses for drawing and
ironing ductile metal blanks or cups to form thin-walled seamless
metal cans suitable for storage of liquids or semi-liquid
substances such as beverages, food stuffs, aerosols and paints.
In order to function effectively, ejector mechanisms for
thin-walled cans must quickly overcome forces from a number of
sources. For example, since the axial walls and edge portions of
the bottoms of the cans are formed by drawing and ironing the
blank's ductile metal back along the punch between the walls of the
punch and dies, frictional forces are formed all along the walls of
the can. Furthermore, in many drawing and ironing presses, the
punch often has a slightly irregular or tapered shank, wherein the
front of the punch often has a slightly larger diameter than the
rear portion. This taper produces cans of slightly increased
thickness near the top so that the top of the can will be able to
withstand subsequent machining operation associated with the
addition of a top to the can. Such a taper produces a "hump", which
in turn creates mechanical forces between the punch and can near
the tapered top portion of the can which the ejector mechanism must
also overcome.
Hitherto known ejector mechanisms for thin-walled cans have
utilized such means as ejector pins operating from either the die
side or the punch side to deliver a sharp tap to the bottom of the
can, pneumatic means to deliver a blast of air to the bottom of the
can, strippers or grippers to apply pressure to the top edges of
the can from the punch side as the punch starts its return stroke,
or combinations of these means such as those taught in U.S. Pat.
No. 3,165,203 and 3,719,069. Owing to the high mechanical and
frictional forces and the thinness of the walls of the can, the
cans are often deformed by these types of ejector actions.
Furthermore, the relatively thin ejector pins are, themselves,
sometimes deformed or broken by the high buckling stresses caused
by their impact with the cans. These buckling stresses are
particularly prevalent in ejection systems wherein the pins are
activated by means of electrical or pneumatic contacts which in
turn activate the ejection pin driving means. This is because
pneumatic or electrical make and break devices take slightly
varying time spans to activate the ejector pins particularly as
these devices wear in use. This results in improperly timed
ejection actions and hence higher buckling stresses. Thus, "timing"
of the ejection is of the utmost importance, particularly when
rejections are carried out at rates in excess of 100 cans per
minute.
SUMMARY OF THE INVENTION
A specific object of this invention is to provide an ejector
mechanism which operates through completely mechanical means, that
is, through mechanical linkages without the need for electrical or
pneumatic operations. It being understood, however, that the
ejector mechanism of this invention is designed to initially loosen
the workpiece from the mechanical and frictional forces caused by
the drawing and ironing process. After the workpiece is free of
these forces, then known devices for holding and conveying the
finished workpiece away from the die and punch work area may be
used. Such devices form no part of this invention. It should also
be understood that known pneumatic means could be used in
synchronization with the ejector mechanism of this invention to
prevent the collapse of the can due to vacuum forces created by the
withdrawal of the punch in the can; again, however, such known
devices form no part of this invention. It is a particular object
of this invention to eject thin-walled cans from the work area of
drawing and ironing presses at rates which may exceed 100 cans per
minute without harmful deformations to said cans. It is still
another object of this invention to reduce tool wear in the
ejection mechanism in ways which will be hereinafter described.
Ejector mechanisms constructed in accordance with this invention
comprise a nosepiece located at the working end of a punch. Said
punch forms a fixed part of a punch carriage. The nosepiece is
capable of reciprocal motion with respect to the punch with the
reciprocal motion being independent of the motion of the punch. The
nosepiece is connected to a push rod which transmits independent
reciprocal motions to the nosepiece as the punch makes its rearward
stroke out of the die. The push rod has connecting points for
pivotally receiving actuator arms which are in turn pivotally
connected to actuators. The actuators are pivotally mounted at one
end to a known type of punch carriage which forms no part of this
invention. The actuators are so adapted and arranged that the
actuator initially jams against a biased trip dog during the return
stroke of the punch carriage. This causes the actuator to pivot
forward about its punch carriage pivot mounting. Thus, the actuator
arm, the push rod, and hence the nosepiece is forced forward to
eject the workpiece. As the punch carriage continues its rearward
stroke, the actuator slips past the biased trip dog. When this
happens, a push rod biasing means forces the push rod back to its
original position before the punch carriage completes its rearward
stroke. The return of the push rod is inhibited by a damping means
connected to said push rod to prevent harmful impacts between the
nosepiece and punch as the push rod is forced back by the push rod
biasing means. The punch carriage then completes its rearward
stroke. The actuator is also adapted to slide past the biased trip
dogs as the punch carriage makes its forward or work stroke.
Other and further objects of the present invention will be apparent
from the following description and claims. The accompanying
drawings shown only the preferred embodiments of the present
invention and the principles thereof, and what is now considered to
be the best mode contemplated for applying these principles. Other
embodiments of the invention utilizing the same or equivalent
principles may be made as desired by those skilled in the art
without departing from the scope of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Throughout this specification and in the appended claims the terms
"cylindrical can" and "can" are employed in the general sense as
referring to a configuration generated by movement of a straight
line in a closed path about a parallel straight line axis; thus,
these terms include cylinders of generally rectangular, square,
elliptical and other cross-sectional configurations, as well as the
usual cylinders of circular cross-section. In the apparatus
embodiments of this invention illustrated in the drawings, the
drawing and ironing press is shown as having a generally circular
configuration, and this is also true with respect to the
workpieces, such as the lower portions of beer cans, produced by
said drawing and ironing press. It being understood that
modification to other cross-sectional configurations can be readily
accomplished by changing the die and punch to the appropriate
configuration. Furthermore, it will be understood by those skilled
in the art that although the can is envisioned as having a full
bottom in the approximate conformation of the nosepiece, the
mechanism would operate on cans without full bottoms.
Likewise, even though the term "drawing and ironing" is generally
used throughout this application, those skilled in the art will
recognize that "cold ironing" or "extruding" presses could also
utilize the ejection mechanisms taught by this invention and hence
these terms should be considered as equivalents insofar as they
apply to this invention.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a known drawing and ironing press
with the ejector mechanism of this invention associated therewith.
The punch carriage, and hence the punch which is fixedly attached
to said punch carriage, is shown in its full forward position.
FIG. 2 is a sectional view of the drawing and ironing press and
ejector mechanism showing the action of the ejector mechanism at a
point just after the actuators have slid past the trip dogs during
the rearward stroke of the punch carriage,
FIG. 3 is a sectional view of the drawing and ironing press and
ejector mechanism showing the push rod returned to a full rearward
position in the damping means after the actuators have slid past
the trip dogs, but before the punch carriage has reached its full
rearward stroke position. The figure shows a new workpiece in
position ready to be extruded as the punch comes forward.
FIG. 1 is a sectional view of a drawing and ironing press 10, in
which an ejection mechanism 11 constructed in accordance with one
embodiment of the present invention is incorporated. The press 10
comprises a punch carriage 12 having a known power means not shown
for driving said punch carriage 12 between a full forward position
FF and a full rearward position FR. The punch carriage 12 has a
punch 13 fixedly attached so that said punch carriage 12 and punch
13 move in unison. A work piece 14 is "ironed" or "extruded"
between the punch 13 and a die or series of dies 15 as the punch 13
moves into the die(s) 15. The punch 13 is substantially hollow
throughout its center to allow reciprocal passage of push rod 16. A
nosepiece 17 which substantially forms the forward or working end
of the punch 13 is reciprocally mounted to move forward and
rearward with respect to said forward end of the punch 13 as the
punch carriage 12, and hence the punch 13 makes its rearward
stroke. The rear end of the nosepiece 17 is fixedly mounted to the
front end of the push rod 16. Another point on said push rod 16,
shown as the rear end in FIG. 1, is fixedly mounted for
reciprocation therewith to a damping means 18. The damping means 18
shown in FIG. 1 is a known two-stage hydraulic damper having a
first-stage piston 19 and a second-stage piston 20. The push rod 16
is provided with an abutting means such as a back up ring 21 for
contacting a biasing means depicted as a spring 22 in FIG. 1. The
purpose of said spring 22 is to force the push rod 16 far enough to
the rear that the nosepiece 17 returns to the front of the punch 13
when the spring 22 is allowed to decompress. When the punch
carriage 12 is in the full forward position FF shown in FIG. 1, the
other end of the spring 22 rests in a substantially decompressed
state against a spring housing 23 which forms a fixed part of the
punch carriage 12. The push rod 16 is also fixedly provided with at
least one connector 24 for pivotal connection with an actuator arm
25. Said actuator arm 25 is pivotally connected at one end to the
push rod connector 24 and pivotally connected at the other end to
an actuator 26. The actuator 26 is pivotally mounted to the punch
carriage 12 at one end and pivotally mounted to the actuator arm 25
at some point adjacent to the actuator's punch carriage pivot
mounting point. The actuator 26 is forced to pivot forward about
the actuator's punch carriage pivot mounting point by a lever
action delivered to the actuator 26 by a trip dog 27 after the
punch carriage 12 begins its rearward stroke with said actuator 26
being so adapted and arranged that it initially jams against the
trip dog 27 to create the levered pivot action of the actuator 26
about its punch carriage pivot mounting point, and then slides past
the trip dog 27 after the actuator 26 has pivoted far enough
forward to allow the actuator 26 to slide past the trip dog 27 as
the punch carriage continues on its rearward stroke. The actuator
26 is also so adapted and arranged that it slips past the trip dog
27 without creating any forward movement of the actuator arm 25
during the forward stroke of the punch carriage 12.
FIG. 1 shows the trip dog 27, located a distance d from the rear
edge of the actuator 26 when the punch carriage 12 is in the full
forward FF position. The trip dog 27 has a biasing means for
returning said trip dog to an actuating position when the trip dog
is not in contact with the actuator 26. The actuating end of the
trip dog 27 is so adapted and arranged that the actuating end of
the trip dog 27 initially jams against the actuator 26 after the
punch carriage 12 begins its rearward stroke. The trip dog
actuating end arrangement then allows the actuator 26 to slide past
the actuating end of the trip dog as the punch carriage 12
continues on its rearward stroke. The actuating end of the trip dog
27 is so adapted and arranged that it allows the actuator 26 to
slide past the biased trip dog 27 without a forward lever action of
the actuator 26 as the punch carriage 12 makes its forward
stroke.
FIG. 2 is a sectional view of the drawing and ironing press 10, in
which the ejection mechanism 11 constructed in accordance with one
embodiment of this invention is shown at a position where the
actuator 26 is just sliding past the trip dog 27 during the
rearward stroke of the punch carriage 12. The actuator 26 has
forced the actuator arm 25 completely forward and the actuator arm
25 has forced the push rod 16 completely forward and the push rod
16 has in turn pushed the nosepiece 17 forward to free the
workpiece 14 from the forces holding the workpiece 14 to the pucnh
13. At this point in the ejection process other known devices for
holding and conveying the finished workpiece 14 away from the die
and punch work area may be utilized. Such devices are not shown and
form no part of this invention. In the position shown in FIG. 2 the
spring 22 has been put in compression between the back up ring 21
and the spring housing 23. The first stage piston 19 and the
second-stage piston 20 have been pulled forward by the push rod 16
where they are now ready to dampen the return of push rod 16, and
hence the return of the nosepiece 17 to the punch 13.
FIG. 3 is a sectional view of the drawing and ironing press 10, in
which the ejection mechanism 11, constructed in accordance with one
embodiment of this invention, is shown at a position in the return
stroke of the punch carriage 12 where the actuator 26 is no longer
in contact with the trip dog 27 and hence the spring 22 has
decompressed. This decompression has preferably taken place before
the punch carriage 12 has gone to the full rearward strike position
FR. The forces supplied by the decompressing spring 22 have driven
the push rod 16 rearward and hence pulled the nosepiece 17 back
into contact with the front end of the punch 13. The impact of the
return of the nosepiece 17 to the punch 13 has been softened by the
damping means 18. A new workpiece 14 in the form of a blank or cup
has been placed in position for drawing and ironing when the punch
13 makes its forward stroke.
Although a preferred embodiment of this invention is illustrated,
it will be realized by those skilled in the art that modifications
of the structual details may be made without departing from the
mode of operation and the essence of this invention. For example,
in all the figures shown above, the ejector mechanism is shown as
being bilaterally symmetrical, i.e., actuator arms, actuators, and
trip dogs are shown on each side of the push rod axis. This is the
preferred arrangement, although it should be understood that the
ejector mechanism would work with just one of each of the above
elements in the arrangement shown in the drawings.
Furthermore, the push rod biasing means could be a device other
than the spring shown in the above figures. Likewise, a damping
means other than the hydraulic means shown in the figures above
could be utilized. The two-stage hydraulic means shown above is
preferred, however, since the first stage can be adapted to allow a
damped, but nonetheless high speed return of the nosepiece to the
ram under the influence of the biasing means and then further
dampen the impact of the nosepiece to the ram at the end of this
return to prevent harmful impacts between the nosepiece 17 and the
punch 13. This combination is particularly well suited for the high
speed operations contemplated by this invention.
Similarly, applicants have discovered that harmful mechanical
impacts between the actuator and trip dog can be minimized if the
distance between the rear edge of the actuator and the foward edge
of the trip dog shown in FIG. 1 is less than about 2 inches and
most preferably less than about 1/4 of an inch. With this
arrangement, the actuator has not had time to achieve a high
rearward velocity before the rear edge of the actuator 26 and the
front edge of the trip dog 27 impact. It should also be noted with
respect to the actuator and trip dog that other geometric forms
such as, for example, rounded edges would have the capability of
sliding past each other in the rearward direction to lever the
actuator and not lever the actuator during the forward stroke of
the punch carriage. The trip dog can be biased toward the actuating
position by any suitable biasing means such as springs, air
pressure, etc.
Finally, it will be understood by those skilled in the art that the
relationship between the punch and the die could be reversed since
it is not absolutely essential that the punch be the movable
element of the die and punch combination.
Therefore, except insofar as they are claimed in the appended
claims, structural details may be varied widely without modifying
the mode of operation. Accordingly, the appended claims and not the
aforesaid descriptions are determinative of the scope of this
invention.
* * * * *