U.S. patent application number 10/494917 was filed with the patent office on 2005-02-17 for tool made from plastic.
Invention is credited to Hochwald, Peter, Hufenbach, Werner, Kunze, Klaus, Lowen, Joachim, Mekkaoui Alaoui, Mohamed, Straube, Oliver, Vossberg, Jurgen.
Application Number | 20050034504 10/494917 |
Document ID | / |
Family ID | 7705293 |
Filed Date | 2005-02-17 |
United States Patent
Application |
20050034504 |
Kind Code |
A1 |
Mekkaoui Alaoui, Mohamed ;
et al. |
February 17, 2005 |
Tool made from plastic
Abstract
The invention relates to a tool comprising a partial region made
from plastic, in which a material with slide bearing properties is
inlaid. Said tool is a moulding tool, which can be applied, for
example, in the deep-drawing of metal pieces. The partial region in
which the material with slide bearing properties, for example
graphite, is inlaid, is a front layer (11) of the tool, comprising
the moulding region thereof. The backing (12) of the tool is also
made from plastic, which can optionally contain conventional
fillers. The front layer (11) of the tool, reinforced, for example,
with graphite, permits a deep drawing optionally without the use of
lubricants, whereby the moulding region of the tool has good slide
bearing properties and a high pressure resistance.
Inventors: |
Mekkaoui Alaoui, Mohamed;
(Hannover, DE) ; Vossberg, Jurgen; (Wolfsburg,
DE) ; Hufenbach, Werner; (Dresden, DE) ;
Kunze, Klaus; (Dresden, DE) ; Hochwald, Peter;
(Wehr, DE) ; Straube, Oliver; (Blankenfelde,
DE) ; Lowen, Joachim; (Bielefeld, DE) |
Correspondence
Address: |
PROSKAUER ROSE LLP
PATENT DEPARTMENT
1585 BROADWAY
NEW YORK
NY
10036-8299
US
|
Family ID: |
7705293 |
Appl. No.: |
10/494917 |
Filed: |
October 7, 2004 |
PCT Filed: |
November 6, 2002 |
PCT NO: |
PCT/EP02/12389 |
Current U.S.
Class: |
72/477 |
Current CPC
Class: |
B21D 37/01 20130101 |
Class at
Publication: |
072/477 |
International
Class: |
B21D 031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 9, 2001 |
DE |
101-55-234.3 |
Claims
1. A tool comprising a section made of a plastic, wherein a
material with lubricating properties is embedded in the plastic,
the tool is a forming tool, and the section made of plastic is a
forming region of the tool.
2. The tool according to claim 1, wherein the section made of
plastic comprises a front layer of the tool.
3. The tool according to claim 1, wherein the material with
lubricating properties is graphite.
4. The tool according to claim 3, wherein the graphite is graphite
powder.
5. The tool according to claim 4, wherein the graphite powder has a
particle size between approximately 50 and approximately 250
.mu.m.
6. The tool according to claim 2, wherein the thickness of the
front layer is at least 5 mm.
7. The tool according to claim 6, wherein the thickness of the
front layer is between approximately 5 and approximately 15 mm.
8. The tool according to claim 1 further comprising a rear
structure made primarily of plastic.
9. The tool according to claim 8, wherein the plastic of the rear
structure contains a filler.
10. The tool according to claim 9, wherein the filler is selected
from the group consisting of aluminum, gray cast iron, sand, and
mixtures thereof.
11-13. (Canceled)
14. The tool according to claim 10, wherein the filler is in powder
form.
15. The tool according to claim 1, wherein the forming tool is a
deep-drawing tool.
16. The tool according to claim 1, wherein the forming tool is a
die, hold-down device, or female die for the deep-drawing of metal
parts.
17. The tool according to claim 1, wherein the forming tool is a
deep-drawing tool for forming metal parts for automobile
construction or aircraft construction.
18. A process for the formation of a part comprising the steps of
obtaining a workpiece and subject the workpiece to the action of a
tool according to claim 1.
19. The process of claim 18, wherein the process is a deep-drawing
process, and the workpiece is sheet metal.
Description
[0001] The present invention relates to a tool including a section
made of a plastic, in which a material with lubricating properties
is embedded.
[0002] Tools made of steel or gray cast iron are conventionally
used for forming processes, deep-drawing processes. More recently,
forming tools made at least partially of plastic have also become
known, which can be used for certain applications, such as for
small series. For example, DE 199 00 597 A1 describes a sheet metal
forming tool and a method for its production, in which the tool is
manufactured with layers of plastic films that are glued on top of
each other one after another. In this process, plastic powder can
also be filled, layer by layer, into a working space and then
sintered by means of a laser beam. However, the processes described
in this document are relatively complex and, furthermore, such
tools are only feasible for the forming of workpieces that are
produced in small series with limited numbers of production
units.
[0003] DE 93 18 272.4 U1 describes a tool for the non-cutting
forming of workpieces, with the tool per se being made of a
metallic material, especially gray cast iron, while a guide
component of the tool, which has a slide face, is made of a
duroplastic with a fiber or woven material insert and embedded
laminar graphite. This is done to improve the lubricating
properties and reduce wear. This known tool is made only partially
of plastic in the region of tool components that are displaceable
relative to one another, such as slides and the like, but not in
the forming regions themselves, in which the tool acts on a
workpiece. Instead, a bending die that forms a forming region of
the tool is made of metal.
[0004] The object of the present invention is to provide a tool
made of an alternative material and having advantageous properties
in comparison to conventional tools.
[0005] This object is attained by providing a tool according to the
invention of the type stated initially, having the characterizing
features of the principal claim. According to the invention, the
tool is a forming tool and the section made of plastic, in which a
material with lubricating properties is embedded in the plastic, is
a forming region of the tool. The abovementioned section of the
tool, made of a plastic in which a material with lubricating
properties is embedded, preferably includes a front layer of the
tool. This section of the tool can contain graphite, for example,
as a material with lubricating properties. The plastic of the tool
preferably contains graphite powder in this section, especially
graphite powder with a particle size of between approximately 50
and approximately 250 .mu.m. The thickness of the abovementioned
front layer in the forming region of the tool, in which the plastic
contains a material with lubricating properties, is preferably at
least approximately 5 mm. For example, the thickness of this front
layer lies within a range of between approximately 5 and
approximately 15 mm.
[0006] A preferred embodiment of the object attained according to
the invention provides that not only the forming region of the tool
is made of plastic, but that the tool also has a rear structure
essentially made of plastic. Accordingly, the entire tool can be
made of plastic, although only the section that forms the forming
region must be made of a plastic in which a material with
lubricating properties is embedded. A less expensive material can
be used for the rear structure. The rear structure of the tool is
preferably made of a plastic containing a filler. Fillers such as,
for example, aluminum and/or gray cast iron and/or sand, preferably
in powdered form, are possible. Thus, the rear structure is made of
a material having sufficient resistance to pressure. The rear
structure can, for example, be made of a full cast material
including the plastic and the filler or fillers. On the one hand,
the front layer of the tool, which serves as the forming region,
has increased resistance to pressure in the regions that come into
contact with the workpiece to be formed, while the lubricating
capacity in the region of the contact surface is assured by the
embedded material with lubricating properties. A self-lubricating
effect is essentially achieved in the forming region, i.e., in the
region of the front surface of the tool, thus enabling the use of
conventional lubricants to be entirely or largely eliminated.
[0007] Within the scope of the present invention, the production of
deep-drawing tools is preferred. These tools can be, for example,
dies, hold-down devices, or female dies, especially for the
deep-drawing of metal parts. The deep-drawing tools according to
the invention are especially suitable for the forming of metal
parts, e.g., in automobile or aircraft production. Embedding the
material with lubricating properties prevents, during the
deep-drawing of a metal plate, for example, which is stressed in
this process in a tensile direction perpendicular to the direction
of motion of the deep-drawing tool, particles, especially filler
particles, from being torn out of the plastic matrix, resulting in
cracks in the tool.
[0008] The advantages of the plastic tools made with the materials
according to the invention, in comparison to conventional steel
tools, lie, for example, in the material costs, which are reduced
by up to about 70%. The plastics used to manufacture the tools are
more easily machined, reducing the use of machinery in production
of the tools. Energy and output requirements during the machining
work required to produce the tools can be reduced by 65%, for
example. The break-in time is also shorter than with steel tools,
by up to 60%, for example. The use of plastics according to the
invention for production of the tools leads to a substantial
reduction in weight of up to 60%, for example, and thus to a
reduction in loads on crane equipment. The tools can be modified
more flexibly and cost-effectively, thereby achieving a high degree
of cost, time, and energy savings. The tools are also suitable for
recycling, because they can be fully recycled as filler material in
the production of new plastic tools, thus eliminating disposal
costs.
[0009] The elastic behavior of the plastics results in improvement
of the quality of the formed workpieces. Embedding graphite in the
plastic of the tools produces a self-lubricating effect on the
contact surfaces of the tool. If it is even necessary to
additionally use liquid lubricants during forming, the amount of
lubricant necessary can be significantly reduced, for example, by
approximately 3 g/m.sup.2. The frictional conditions during
deep-drawing are improved by incorporating graphite powder into the
plastic. As a result of the elimination of or reduction in liquid
lubricants during deep-drawing, dirt accumulation in the work area
is significantly reduced, thereby benefiting the environment.
[0010] The preferred modular construction of the plastic tools
according to the invention, including the front layer (forming
region) and the rear structure, allows for the reuse of a large
portion of the tools. Because of the incorporation of the material
with lubricating properties into the front layer and the resulting
elimination (for the most part) of liquid lubricants, the need to
degrease the finished drawn parts is also eliminated, as a rule.
The features specified in the subclaims relate to preferred
embodiments of the solution of the object attained according to the
invention. Further advantages of the invention can be inferred from
the following detailed description.
[0011] In the following, the invention will be explained in greater
detail, using exemplary embodiments with reference to the attached
drawings, which show
[0012] FIG. 1 a highly schematically simplified perspective view to
explain a deep-drawing process by means of a tool according to the
invention;
[0013] FIG. 2 a second schematically simplified view to explain the
deep-drawing process;
[0014] FIG. 3 a schematically simplified perspective view of a tool
according to the invention installed into a deep-drawing
device;
[0015] FIG. 4 a perspective view of a finished part, which was
deep-drawn by means of a tool according to the invention.
[0016] First, we refer to FIG. 1. The drawing shows, in a highly
schematically simplified perspective view, an array of tools for
deep-drawing a sheet metal component 10. An upper tool part 8 is
provided for forming the sheet metal component 10 in a deep-drawing
process, as well as a lower tool part 9 in the form of a female die
that accepts the upper tool part 8. The upper tool part 8 includes
a rear structure 12 of plastic and a front layer 11 that forms the
forming region, which is also made of plastic; however, a graphite
powder 7 is embedded in this plastic to achieve a self-lubricating
effect while forming a sheet metal component 10.
[0017] As a rule, the plastic that forms the rear structure 12 of
the tool also contains fillers, although they can be fillers of a
conventional nature, so as to provide the tool with certain desired
characteristics, such as ensuring that the rear structure 12 has an
adequate resistance to pressure. The lower tool part 9 is also made
of plastic; a conventional plastic can be used here as well,
provided it is not used in the forming regions. It is recommended,
however, even in the lower tool part 9, that the regions that come
into contact with the sheet metal 10 to be deep-drawn during the
forming process be made of a plastic with the incorporated
lubricating material. This is specified in greater detail below,
with reference to FIG. 2, which illustrates, in a schematically
simplified depiction, the forces acting during the deep-drawing
process.
[0018] FIG. 2 shows the position of a sheet metal component 10
between the front layers 11 of an upper tool part 8 and a lower
tool part 9. In both cases, the front layers 11, which are made of
plastic, contain an embedded graphite powder 7 to achieve the
lubricating effect. In the drawing, the arrow indicates that,
during the deep-drawing process, a shearing force acts on the sheet
metal 10 as well as on the front surfaces of the two tools, which
essentially acts perpendicularly to the direction of motion of the
tools. As a result of this shearing stress between the sheet metal
10 and the front layers 11 of the upper tool part 8 and lower tool
part 9, each provided with embedded graphite, a lubricating effect
is achieved which is attributable to the lubricating properties of
the graphite. This eliminates the need to use a liquid lubricant.
Moreover, it was found that, as a result of embedding the graphite
in the respective front layers 11 of the tools, their resistance to
pressure at the contact surface is also increased.
[0019] Using a drawing die of the type depicted schematically in
FIG. 2, several hundred parts were drawn. Then the condition of the
tool was examined, and it was concluded that it would easily allow
for the drawing of thousands of additional parts.
[0020] FIG. 3 shows, once again and somewhat more precisely, a
section of deep-drawing device in perspective view in which it is
possible to discern the plastic rear structure 12 of the tool,
which is fastened to an upper plate 20 of the device, which is
lowered during the deep-drawing process. This lowering of the plate
20 and the tool made of plastic takes place in a tool guide 14 of
the device, which will not be explained in greater detail here.
[0021] The front layer 11 of the tool, provided with embedded
graphite and also made of plastic, as well as the hold-down devices
13 of the device, located beneath this front layer, are also
visible in FIG. 3.
[0022] FIG. 4 shows a perspective view of a metal component that
was deep-drawn from a piece of sheet metal by means of a tool of
the type according to the invention. It is a shielding plate 15 for
a motor vehicle. As can be seen, the shielding plate 15 has,
following the forming process, convex curved regions 18 as well as
concave curved regions 19. The shielding plate 15 also has various
perforations 16 as well as formed areas incorporated during the
deep-drawing process, such as the well-like depression 17
recognizable in the drawing. It was found that such metal
components can be deep-drawn in outstanding quality with the tools
according to the invention.
List of Reference Characters
[0023] 7 Graphite Powder
[0024] 8 Upper Tool Part
[0025] 9 Lower Tool Part
[0026] 10 Sheet Metal Component
[0027] 11 Front Layer
[0028] 12 Rear Structure
[0029] 13 Hold-down Device
[0030] 14 Tool Guide
[0031] 15 Shielding Plate
[0032] 16 Perforations
[0033] 17 Depression
[0034] 18 Convex Curved Area
[0035] 19 Concave Curved Area
[0036] 20 Plate
* * * * *