U.S. patent application number 11/374385 was filed with the patent office on 2006-09-14 for press-actuation system.
This patent application is currently assigned to UHLMANN Pac-Systeme GmbH & Co. KG. Invention is credited to Kurt Lammle, Ulrich Laupheimer, Georg Pfau.
Application Number | 20060201226 11/374385 |
Document ID | / |
Family ID | 36120863 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060201226 |
Kind Code |
A1 |
Laupheimer; Ulrich ; et
al. |
September 14, 2006 |
Press-actuation system
Abstract
A press has upper and lower dies, an actuating element spaced
vertically from one of the dies, and a platen carrying the one die
and between the element and the one die. A membrane defines a
closed chamber having one side operatively bearing vertically on
the platen and an opposite side bearing vertically on the element.
A fluid supply pressurizes the chamber and maintains in the chamber
a predetermined pressure. An actuator connected to the element
vertically displaces the element, platen, and one die.
Inventors: |
Laupheimer; Ulrich;
(Schemmerhofen, DE) ; Lammle; Kurt; (Ehingen,
DE) ; Pfau; Georg; (Laupheim, DE) |
Correspondence
Address: |
THE FIRM OF KARL F ROSS
5676 RIVERDALE AVENUE
PO BOX 900
RIVERDALE (BRONX)
NY
10471-0900
US
|
Assignee: |
UHLMANN Pac-Systeme GmbH & Co.
KG
|
Family ID: |
36120863 |
Appl. No.: |
11/374385 |
Filed: |
March 13, 2006 |
Current U.S.
Class: |
72/351 |
Current CPC
Class: |
B66F 3/35 20130101 |
Class at
Publication: |
072/351 |
International
Class: |
B21D 22/21 20060101
B21D022/21 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 12, 2005 |
DE |
102005011434.2 |
Claims
1. A press comprising: upper and lower dies; an actuating element
spaced vertically from one of the dies; a platen carrying the one
die and between the element and the one die; a membrane defining a
closed chamber having one side operatively bearing vertically on
the platen and an opposite side bearing vertically on the element;
supply means for pressurizing the chamber and maintaining in the
chamber a predetermined pressure; and drive means including an
actuator connected to the element for vertically displacing the
element, platen, and one die.
2. The press defined in claim 1 wherein the platen and element
together form a compartment holding the membrane.
3. The press defined in claim 2 wherein the platen is provided with
guide bars in which the element is vertically slidable.
4. The press defined in claim 2 wherein the platen is formed with a
cavity open toward the element and holding the membrane.
5. The press defined in claim 1 wherein the supply means
pressurizes the chamber with a gas.
6. The press defined in claim 5 wherein the membrane forms a
bladder.
7. The press defined in claim 1, further comprising: a source of
fluid under pressure; a valve between the source and the chamber;
and control means connected to the valve and including a sensor
connected to the chamber for determining a pressure therein for
operating the valve according to a sensed pressure for maintaining
the predetermined pressure in the chamber.
8. The press defined in claim 7 wherein the valve includes a
pressure-reducing valve.
9. The press defined in claim 7 wherein the valve includes a
proportional valve.
10. The press defined in claim 1 wherein the chamber is subdivided
into a plurality of individually controllable compartments.
11. The press defined in claim 1, further comprising a second
actuating element spaced vertically from the other of the dies; a
second platen carrying the other die and between the second element
and the other die; and a second membrane defining a closed chamber
having one side operatively bearing vertically on the second platen
and an opposite side bearing vertically on the second element, the
supply means also pressurizing the second membrane.
12. The press defined in claim 1 wherein the supply means maintains
in the chamber a substantially constant pressure regardless of a
vertical position of the one die and element.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to pres. More particularly
this invention concerns an actuation system for a press.
BACKGROUND OF THE INVENTION
[0002] A typical press used, for example, in a packing machine to
laminate together two plastic foils has an upper die and a lower
die, normally heated. Typically the upper die has a planar lower
face and the lower die has a planar upper face formed with an array
of upwardly open pockets. A planar upper foil and a lower foil
formed with an array of upwardly open product-containing blisters
are passed horizontally through the press. The two dies are pressed
together between advance steps of the foils when the blisters are
aligned with the pockets in the lower die to laminate the two foils
together between the blisters. Such systems are described in German
patent documents 197 40 988 and 74 05 441 and in U.S. Pat. No.
5,105,603.
[0003] The two dies are relatively large and quite massive, and the
foils are quite thin and are formed of a moderately fragile
plastic. It is therefore essential that the dies be moved together
with enormous precision so as to press the foils together with just
enough force that they bond together, but not so much that they
extrude out or are damaged.
[0004] Obviously the problem here is that any slight misalignment
can result in a spoiled workpiece. If the two foils are not solidly
bonded together, the resultant package is unusable. Similarly if
the two foils are pinched excessively, there will be weak spots or
holes that also result in an unusable finished product.
OBJECTS OF THE INVENTION
[0005] It is therefore an object of the present invention to
provide an improved press-actuation system.
[0006] Another object is the provision of such an improved
press-actuation system that overcomes the above-given
disadvantages, in particular that ensures that the pressure exerted
on the foils will be uniform and accurately controlled.
SUMMARY OF THE INVENTION
[0007] A press has according to the invention upper and lower dies,
an actuating element spaced vertically from one of the dies, and a
platen carrying the one die and between the element and the one
die. A membrane defines a closed chamber having one side
operatively bearing vertically on the platen and an opposite side
bearing vertically on the element. A fluid supply pressurizes the
chamber and maintains in the chamber a predetermined pressure. An
actuator connected to the element vertically displaces the element,
platen, and one die.
[0008] Thus with this system the pressurizable chamber provided
between the actuator and the one die limits the maximum pressure
the one die can apply to the workpiece. If the actuator, which is
typically a powerful hydraulic cylinder or motor, moves the element
somewhat too far, the chamber will simply deform and the pressure
transmitted to the workpiece will be that in the chamber. In
addition if one of the dies is slightly canted, that is
nonparallel, to the other die, the chamber will deform to allow
them to move parallel without pinching or overly compressing the
workpiece. What is more, the actuator can be set to perform a
simple lifting stroke and any adjustment or fine-tuning of the
closing pressure is handled by the supply system connected to the
force-transmitting chamber.
[0009] What is more, the chamber ensures that the force of the
press actuator, which typically is applied at one or more separate
locations to the actuating element, is distributed over the entire
platen. Thus even if the element deforms, the platen will be
applied smoothly and flatly.
[0010] According to the invention the platen and element together
form a compartment holding the membrane. The platen is provided
with guide bars in which the element is vertically slidable, and/or
the platen is formed with a cavity open toward the element and
holding the membrane and in which the actuating element is
slidable. The cavity receives the membrane with some play, that is
lateral spacing, so it can spread and deform as needed.
[0011] The supply system pressurizes the chamber with a gas,
normally air. This makes it possible to control the
workpiece-clamping pressure accurately and very easily. What is
more, such a pneumatic system is environmentally friendly as
compared, for example, to a oil-filled hydraulic system, as any
leakage does not create a problem and, if minor, does not even
require shutting down the press.
[0012] The membrane according to the invention forms a bladder. It
can have several compartments for local control of pressure, or be
formed as a stack of compartments. The bladder can easily be
exchanged or replaced. When multiple bladders are used, they can be
switched out to achieve different pressures in different areas, and
generally provide local pressure control.
[0013] The press further has according to the invention a source of
fluid under pressure, a valve between the source and the chamber,
and a controller connected to the valve and including a sensor
connected to the chamber for determining a pressure therein for
operating the valve according to a sensed pressure for maintaining
the predetermined pressure in the chamber. The valve includes a
pressure-reducing valve and/or a proportional valve. The sensor can
be associated with a comparator to establish upper and lower
pressure limits for the valve and operate in a feedback system to
maintain the pressure in the chamber substantially constant. A
pressure-reducing valve limits the maximum pressure to prevent
damage to the workpiece no matter what else occurs.
[0014] According to the invention the press further has a second
actuating element spaced vertically from the other of the dies, a
second platen carrying the other die and between the second element
and the other die, a second membrane defining a closed chamber
having one side operatively bearing vertically on the second platen
and an opposite side bearing vertically on the second element. The
supply means also pressurizes the second membrane.
BRIEF DESCRIPTION OF THE DRAWING
[0015] The above and other objects, features, and advantages will
become more readily apparent from the following description,
reference being made to the accompanying drawing in which:
[0016] FIG. 1 is a partly diagrammatic vertical section through
part of a press according to the invention; and
[0017] FIG. 2 is a partly diagrammatic vertical section through a
press in accordance with the invention.
SPECIFIC DESCRIPTION
[0018] As seen in FIG. 1 a press 1 according to the invention has a
lower die 2 typically formed with an array of upwardly open pockets
and carried on a massive cast platen 3. An actuating plate or
element 5 underneath the plate 3 is vertically reciprocal by an
actuator, e.g. a motor or hydraulic cylinder, shown schematically
at 4 to open and close the press 1. The platen 3 is formed with a
downwardly open cavity 13 in which the plate 5 can slide limitedly
vertically and bars 11 surrounding the cavity 13 also guide the
plate 5 and prevent it from becoming disconnected in a lowermost
position from the platen 3.
[0019] According to the invention a flexible and even somewhat
elastomeric membrane 7 forming a bladder 10 defining a closed
chamber 19 is carried with some lateral clearance in the cavity 13.
It is connected via a feed line or passage 13 in the platen 3 with
a supply conduit 9 connected via a pressure-limiting valve 12 and a
proportional valve 15 with a supply 17 of fluid, here air, under
relatively high pressure.
[0020] FIG. 2, where reference numerals identical to those of FIG.
1 but with primes are used for structurally and/or functionally
identical parts, shows how an upper die 2' can be carried on a
plate 5' that is fixed as indicated at 18, or that can also be
movable by its own actuator.
[0021] Both of the supply lines 9 and 9', in which the fluid
pressure is identical to that in the respective bladders 10 and
10', are connected to respective pressure sensors 14 and 14' in
turn connected to a controller 16 that also operates the valves 12,
12', 15, and 15'. This controller 16 therefore maintains a
perfectly uniform and relatively low pressure in both of the
bladders 10 and 10', which can be subdivided into individually
pressurizable compartments as indicated at 19 in FIG. 1.
[0022] Thus even through the actuator 4 is dimensioned to shift the
relatively massive structure constituted by the die 2, platen 3,
and actuating element 5 with considerable force, the actual
pressure that the dies 2 and 2' will bring to bear on a pair of
foils F.sub.1 and F.sub.2 passing horizontally in steps in a
direction D through the press 1 is determined by the pressure in
the bladders 10 and/or 10'. As a result it is not necessary to
provide an extraordinarily sensitive and complex control system for
the actuator 4, and it is also not essential to perfectly align the
dies 2 and 2' so they close in perfect parallelism. Instead a
simple pneumatic pressure-control system limits the pressure the
dies 1 and 2' will apply to the workpiece formed by the foils
F.sub.1 and F.sub.2.
* * * * *