U.S. patent application number 10/070565 was filed with the patent office on 2003-09-18 for device for producing castings that comprises a wall can be guided into the casting mold.
Invention is credited to Boehnke, Christian.
Application Number | 20030173053 10/070565 |
Document ID | / |
Family ID | 7648201 |
Filed Date | 2003-09-18 |
United States Patent
Application |
20030173053 |
Kind Code |
A1 |
Boehnke, Christian |
September 18, 2003 |
Device for producing castings that comprises a wall can be guided
into the casting mold
Abstract
The invention relates to a device for producing castings from
flowable or strewable starting material. Said device comprises an
injection unit, out of which the at least partially liquefied
material can be injected into a casting mold. The injection unit
has an inlet opening for supplying the material, and the injection
unit has a chamber with two moveable walls. These walls can either
be moved together in one direction or in opposite directions in
such a manner that the volume of the interior of the chamber can be
altered as desired and/or the interior of the chamber can he
displaced, whereby one or both walls form a portion of the wall
delimiting the mold cavity. The invention provides that both walls
each form a portion of the wall delimiting the mold cavity, whereby
one of the walls can be guided into the casting mold.
Inventors: |
Boehnke, Christian;
(Munster, DE) |
Correspondence
Address: |
LAHIVE & COCKFIELD
28 STATE STREET
BOSTON
MA
02109
US
|
Family ID: |
7648201 |
Appl. No.: |
10/070565 |
Filed: |
July 10, 2002 |
PCT Filed: |
June 30, 2001 |
PCT NO: |
PCT/DE01/02486 |
Current U.S.
Class: |
164/312 ;
164/136 |
Current CPC
Class: |
B22D 17/2015 20130101;
B22D 17/007 20130101 |
Class at
Publication: |
164/312 ;
164/136 |
International
Class: |
B22D 017/08; B22D
035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 7, 2000 |
DE |
10033166.1 |
Claims
1. Device for producing castings out of fusible or dispersible base
material, including an injection unit from which the at least
partially liquefied material can be injected into a mold, wherein
the injection unit has an inlet port for feeding the material, and
wherein the injection unit has a chamber with two movable walls
which may as desired be moved either together in the same direction
or in opposite directions so that the cavity of the chamber may be
varied by volume as desired and/or be displaceable, one of the two
walls forming a section of the wall delimiting the mold cavity (9),
characterized in that the two walls each form a part of the walls
delimiting the mold cavity (9), one of the two walls being movable
into the mold (2).
2. Device according to claim 1, characterized in that the wall
which is movable into the mold (2) is designed as a piston (8)
which is supported within a tubular chamber wall so as to be
longitudinally movable or is supported so as to be movable toward
chamber (5) to perform a sealing function, and that this wall is
movable together with a movable mold section (11) of mold (2).
3. Device according to claim 1, characterized in that the wall
which is movable into mold (2) is designed to partially determine
the surface shape of the casting.
Description
[0001] The invention relates to a device according to the preamble
of claim 1.
[0002] European Patent 1 046 444 A1 discloses a device of this type
according to the species. Three pistons are used to create a
variable-volume chamber for the injection material. In it, two
pistons are axially movable within a tubular cavity, and a third
piston can be moved perpendicularly to the longitudinal axis of the
chamber between the two above-mentioned pistons so as to convey the
material into the mold cavity. The requirement here is that there
be a precise seal between the three pistons relative to one another
and to the chamber. Because of the space requirement and the
demands on the seal, the device according to the species is very
expensive to produce.
[0003] German Patent 199 14 830 A1 describes a device in which two
walls designed as a valve and a piston are axially movable within
the tubular cavity. They adjoin a runner through which the
injection material enters the actual mold cavity.
[0004] German Patent 43 10 755 A1 describes a device in which two
walls, one designed as a nondriven movable clamping disk and the
other as a driven piston, are axially movable within a tubular
cavity. They adjoin a runner through which the injection material
enters the actual mold cavity.
[0005] Replaceable mold inserts which may form sections of the wall
of the mold cavity are known from Ernst Brunnhuber, "Moderne
Druckgussfertigung" [Modern Die-Casting], Fachverlag Schiele und
Schon GmbH, Berlin, 1971, pages 137 and 139.
[0006] The goal of the present invention is to improve a device
according to the species so that it is as efficient as possible,
has compact dimensions, and can be operated as inexpensively as
possible.
[0007] This goal of the invention is achieved by a device having
the characteristic features of claim 1.
[0008] In other words, the invention proposes an approach in which
the movable chamber walls are located not exclusively outside the
mold but are disposed to allow displacement of the chamber contents
into the mold. This approach results in a savings in material since
the sprue can be avoided or considerably reduced. As a result, a
reduction can be made in the quantity of material in circulation
which must be re-cooled and re-melted for each cycle, with the
possible ensuing melting loss in expensive alloy elements, this
melting loss having to be continually replaced.
[0009] Since the sprue/runner can be reduced or completely
eliminated, the amount of heated material, and thus the heat load
on the injection unit and the mold itself, are also reduced,
thereby allowing for shorter cool-down phases and consequently for
a higher number of pieces produced per unit time.
[0010] Since the material enters the mold directly from the chamber
without any intermediate injection channel, larger flow
cross-sections can be used and, as a result, possible deviations in
material flow can be avoided. The material therefore does not need
to be heated to as high a temperature as it otherwise would to
permit the optimal flow-through capability into the mold for
comparatively smaller inlet ports or to permit the proper flow over
long distances. The result is that a lower temperature level can be
set for the molten metal--with the result that this measure allows
the heat load on the device to be reduced, as already mentioned,
shortens cool-down times, and enhances the efficiency of the
device.
[0011] The fact that deviations in material flow can be avoided
allows the load on the device to be reduced since such deviations
may result in premature wear and actual erosion. In addition, this
fact may allow for a reduction in required impelling power since
the conveying resistance of the material can be reduced.
[0012] The fact that the injection unit extends into the mold and
is not located exclusively outside the mold means that the device
can be produced with compact dimensions. This feature is enabled
specifically by the fact that one of the two walls does not merely
extend up to the edge of the mold but may be moved into the
mold.
[0013] One of the two movable walls of the injection unit chamber
may be advantageously designed as the section of the wall of the
mold cavity which is designed to be movable for the purpose of
opening the mold. This approach avoids complex multi-axial
movements and ensures that, when the mold is opened, this injection
unit wall, which is movable into the casting mold, is moved
together with the section of the mold to he opened--thereby
allowing the access to the casting when the mold is opened to
remain unchanged and allowing optimal access to the casting for its
removal.
[0014] The following discussion utilizes an embodiment to explain
the invention in greater detail.
[0015] FIGS. 1 through 6 show a device for producing castings at
various phases of the casting process.
[0016] Reference 1 in FIG. 1 designates a device for producing
castings in a pressure die-casting process.
[0017] Device 1 has a two-part mold 2 which in FIG. 1 is seen in
its closed configuration. Device 1 additionally has an injection
unit 3 which serves to inject the fusible material into the mold 2.
FIG. 1 shows injection unit 3 in an initial phase of its filling
process:
[0018] A conveying unit 4 conveys the molten or at least partially
molten material into a chamber 5 of injection unit 3. The chamber
walls are formed by a round tube 6, an injection piston 7, and a
sealing piston 8.
[0019] In FIG. 1, the volume of chamber 5 is comparatively small.
The chamber volume can be kept to an extreme minimum by moving the
two pistons 7 and 8 very close together. There is assurance at all
times that even oxidation-prone material can be readily processed
since any contact with ambient air is essentially precluded. The
material is conveyed by conveying unit 4 into chamber 5, while
sealing piston 8 is increasingly moved away from injection piston 7
to adjust for the quantity of admitted material, as FIG. 2
shows.
[0020] FIG. 2 shows injection unit 3 in an end phase of filling
when injection unit 3 is essentially filled with the casting
material. The volume of chamber 5 has increased accordingly, and
injection piston 7 continues to be situated at a position in which
the access for conveying unit 4 into chamber 5 is open.
[0021] Once the desired quantity of material has been admitted to
chamber 5, the two pistons 7 and 8 move together. As is evident in
FIG. 3, the result is that chamber 5 is now closed relative to
conveying unit 4.
[0022] Sealing piston 8 is moved out of tube 6 and into mold 2.
This action opens tube 6 and thus, chamber 5. A further movement of
injection piston 7 causes the material to be injected from chamber
5 into mold 2.
[0023] FIG. 4 shows the end position of injection piston 7. Sealing
piston 8 is located inside mold 2 at a position in which it forms
part of the wall of mold 2, which part limits the mold cavity 9
which in turn determines the subsequent contour of the casting. In
the embodiment shown, this is a casting, for example, a
rotationally symmetrical component such as a wheel, a cover, or the
like, in the shaping of which sealing piston 8 directly
participates, and which may be accordingly designed so as to
determine the desired surface shape of the casting. In this case,
the sprue point into the casting can be displaced such that
advantageously there is no "sprue" in the conventional sense, i.e.,
a part which must be removed from the casting and can be used only
as recycled material.
[0024] Alternatively, the approach may be to have one or more
individual end products arranged radially around the region of the
two pistons 7 and 8 such that the casting produced comprises this
number of products plus a sprue which extends from the region
between pistons 7 and 8 up to these products. The sprue is thus
minimal and has no components extending out of the actual mold 2.
In this case, injection piston 7 can extend further than shown in
FIG. 3 to keep the material thickness of the sprue as small as
possible.
[0025] In FIG. 5, it is evident that mold 2 is open. For this
purpose, mold 2 consists of a fixed mold section 10 and another
movable mold section 11. Sealing piston 8 is supported within the
movable mold section 11 and is movable together with or separately
from movable mold section 11 such that, after mold 2 is opened, the
casting can be removed easily and with the same accessibility as
with a conventional injection unit in which all the components are
located outside mold 2.
[0026] After removal of the casting, movable mold section 11 may
again be moved toward fixed section 10 of the mold. This motion
results also in sealing piston 8 being moved toward injection
piston 7 which has remained in its end position. FIG. 6 shows in
purely schematic form that scaling piston 8 has preferably been
moved up to injection piston 7 in order to create a minimum volume
in chamber 5 before mold 2 is completely closed. This allows for
easy venting of the surrounding atmosphere so that chamber 5 is set
for a minimum chamber volume. For safety reasons only, meaning the
avoidance of mechanical damage to pistons 7 and 8, the design of
the piston control shown provides that pistons 7 and 8 do not
directly contact each other.
[0027] Starting with the status shown in FIG. 6, mold 2 is closed,
i.e., the movable section 11 is moved completely against fixed mold
section 10 after which the backplates of mold 2 are locked so that
it is ready to receive the injection pressures.
[0028] One advantage of the device according to the invention is
that sealing piston 8 is allowed to rest against movable mold
section 11 during the injection procedure--with the result that,
advantageously, no expensive and design-specific provision has to
be made in terms of a separate support for sealing piston 8 since
the injection pressures acting on sealing piston 8 are accommodated
by mold 2 or its backplates.
[0029] Subsequent to the situation in FIG. 6 and after mold 2 has
been closed, chamber 5 is displaced by a movement of the same
direction and speed effected by pistons 7 and 8 until chamber 5 is
situated in front of the opening of conveying unit 4 so that a new
operating cycle can take place.
* * * * *