U.S. patent application number 09/902150 was filed with the patent office on 2002-01-24 for method for making a finally shaped forming tool and forming tool made by same.
Invention is credited to Herzbach, Lars Christian, Thiel, Steffen.
Application Number | 20020007700 09/902150 |
Document ID | / |
Family ID | 7649082 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020007700 |
Kind Code |
A1 |
Herzbach, Lars Christian ;
et al. |
January 24, 2002 |
Method for making a finally shaped forming tool and forming tool
made by same
Abstract
The forming tool has a structured forming surface having a high
surface quality and uniform structure so that it accurately
produces a predetermined structure in substrate. To avoid the great
expense and effort associated with final shaping of the forming
tools from blocks or rounded bodies made by forging or by a HIP
method with subsequent machining, first a glass or plastic mold (1)
is made with a molding surface for forming the structured forming
surface of the forming tool, which is the negative of the
structured forming surface for the forming tool with predetermined
dimensions and surface quality in accordance with specifications of
the structured forming surface of the forming tool; then the
molding surface is coated with at least one coating material
selected specifically according to the specifications to form a
cladding body (2) in the glass or plastic mold, next the cladding
body (2) with the structured forming surface is released from the
glass or plastic mold (1) and bonded to a base body with a
non-structured surface of the cladding body (2) in contact with the
base body to form the forming tool with the structured forming
surface.
Inventors: |
Herzbach, Lars Christian;
(Weiterstadt, DE) ; Thiel, Steffen; (Woerrstadt,
DE) |
Correspondence
Address: |
STRIKER, STRIKER & STENBY
103 East Neck Road
Huntington
NY
11743
US
|
Family ID: |
7649082 |
Appl. No.: |
09/902150 |
Filed: |
July 10, 2001 |
Current U.S.
Class: |
76/107.4 |
Current CPC
Class: |
C23C 4/185 20130101;
C03B 11/082 20130101 |
Class at
Publication: |
76/107.4 |
International
Class: |
B21K 005/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 15, 2000 |
DE |
100 34 508.5-16 |
Claims
We claim:
1. A method for making a finally shaped forming tool with a
structured forming surfaces having a uniform surface structure,
said method comprising the following steps: a) making a glass or
plastic mold (1) having a molding surface for forming the
structured forming surface of the forming tool, said molding
surface being a negative of the structured forming surface for the
forming tool with predetermined dimensions and a surface quality in
accordance with specifications of the structured forming surface of
the forming tool; b) coating the molding surface of the glass or
plastic mold (1) with at least one material selected specifically
according to said specifications for the structured forming surface
of the forming tool so as to form a cladding body (2) in the glass
or plastic mold, the cladding body being provided with the
structured forming surface of the forming tool, c) releasing the
cladding body (2) with the structured forming surface from the
glass or plastic mold (1); and d) bonding the cladding body to a
base body with a non-structured surface of the cladding body (2) in
contact with the base body to form the finally shaped forming tool
with the structured forming surface.
2. The method as defined in claim 1, further comprising making said
mold by structuring a plastic body by means of a lithographic
method
3. The method as defined in claim 1, further comprising making said
mold by structuring a glass or plastic body by means of a
mechanical process.
4. The method as defined in claim 1, further comprising making said
mold by structuring a glass or plastic body by means of a thermal
method.
5. The method as defined in claim 1, wherein the coating of the
molding surface of said mold occurs by means of a thermal spraying
method.
6. The method as defined in claim 5, wherein said thermal spraying
method comprises a flame spraying method.
7. The method as defined in claim 6, wherein said flame spraying
method comprises a high velocity oxide fuel flame spraying
method.
8. The method as defined in claim 5, wherein said thermal spraying
method comprises a plasma spraying method.
9. The method as defined in claim 8, wherein said plasma spraying
method comprises a vacuum plasma spraying or low pressure plasma
spraying method.
10. The method as defined in claim 1, wherein said coating of the
molding surface of the glass or plastic mold comprises spraying a
single phase material on the molding surface.
11. The method as defined in claim 1, wherein said coating of the
molding surface of the glass or plastic mold comprises spraying a
material combination in a layered structure or to provide a
material gradient.
12. The method as defined in claim 1, wherein the coating of the
molding surface of the mold takes place to provide a coating
thickness of from 100 .mu.m to 5 mm.
13. The method as defined in claim 1, wherein the coating of the
molding surface of the mold takes place to provide a coating
thickness of up to 20 mm.
14. The method as defined in claim 13, wherein the coating of the
molding surface takes place by a thermal spraying method to form a
coating member and further comprising reinforcing or building up
said coating member by a bonding process.
15. The method as defined in claim 1, wherein said cladding body
(2) released from said mold (1) is combined with said base body (3)
by mechanical means to form said forming tool.
16. The method as defined in claim 1, wherein said cladding body
(2) released from said mold (1) is combined as a part of a
hot-isostatic-press capsule with another material by means of a
hot-isostatic-press process to form the forming tool.
17. A finally shaped forming tool with a forming surface, said
forming tool comprising a base or supporting body (3; 4; 5) and a
cladding body (2) bonded to the base or supporting body, said
cladding body (2) being separately formed from said base or
supporting body with said forming surface.
18. The finally shaped forming tool as defined in claim 17, wherein
said forming surface is uniformly structured.
19. The finally shaped forming tool as defined in claim 17, wherein
said cladding body (2) has a thickness of up to 20 mm and is
mechanically bonded with the base or supporting body.
20. The finally shaped forming tool as defined in claim 17, wherein
cladding body (2) has a thickness of from 100 .mu.m to 5 mm and is
part of a hot-isostatic-press capsule and is combined with another
material by means of a hot-isostatic-press process or by bonding to
form the forming tool.
21. The finally shaped forming tool as defined in claim 15, wherein
the cladding body is formed by a method comprising thermal
spraying.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method of making a
finally shaped forming tool with a forming surface, which is
preferably structured and has a highly uniform structure. The
invention also relates to a finally shaped forming tool with a
forming surface that is preferably structured and that has a highly
uniform structure.
[0003] 2. Related Art
[0004] Forming tools, typically with predetermined structures on
their surfaces, are required to form or shape glass or plastic in a
plasticized state. The predetermined structures in the surfaces of
these forming tools are the negative of the structures produced in
the glass or plastic. These forming tools are typically dies or
roller shaped tools. The structures to be produced can be in the
.mu.m range, e.g. as in the hot forming of so-called channel plates
for flat screen displays of modern TV sets.
[0005] Currently casting methods are used to obtain the finally
shaped forming tool. The structural uniformity obtained with these
casting methods is limited by technical considerations. There are
strict requirements for forming tools in certain different
manufacturing processes, e.g. in the hot forming of glass
substrates regarding structural uniformity as well as chemical
composition. Structural non-uniformities, which can arise because
of casting conditions, e.g. pores, holes, grain size variations,
texture variations, mounds or protruding accumulations, can be
disadvantageously copied into the substrate during the forming
process with the forming tool.
[0006] Forming tools are thus typically forged with high structural
uniformity since clearly more uniform forming thereby results.
[0007] Another process for guaranteeing high structural uniformity
comprises making blocks by a HIP method. Materials are encapsulated
and sealed in a vacuum-tight manner in a sheet structure in the HIP
process(hot-isostatic-press). Subsequently the base block for the
forming tool arises because of the applied high pressure and
temperature. The combination "solid-powder" is an example of a
possible material combination. That means that a supporting
material is processed into a desired form (shape) and after that a
capsule with an internal chamber is provided over the resulting
body. The interior chamber is filled with powder after that. In the
HIP process then the powder is sintered together and combines with
the supporting material forming a diffusion zone.
[0008] An extremely high quality surface structure is obtained in
the HIP process based on small powder grain size up to the nm size
and on the sintering without melt phase.
[0009] The disadvantage of both these manufacturing methods is that
in order to obtain a high degree of structural uniformity final
shaping from initially prepared blocks and/or rounded blanks must
be performed disadvantageously mechanically. This is very
expensive, particularly for wear and corrosion-resistant materials,
such ceramics, high temperature alloys. Also structures in the
.mu.m-range cannot be made economically on these tool surfaces.
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to conduct the
processes of the above-described type so that the finally shaped
forming tools are better than those of the prior art, both in
regard to their geometric form (contour) and also the surface
quality, including their roughness and structure, and also so that
they have higher surface uniformity with distinctly reduced
processing work.
[0011] This object is attained by a process of the above-described
kind for making finally shaped forming tools with the structured
forming surfaces with a high surface uniformity comprising the
following steps:
[0012] a) making a glass or plastic mold having a molding surface
for the finally shaped forming tool that is formed as the negative
of the structured forming surface for the forming tool with
predetermined dimensions with a surface quality, as required by the
forming surface of the forming tool;
[0013] b) coating the molding surface of the glass or plastic mold
with at least one material selected specifically according to the
structured forming surface of the forming tool so as to form a
cladding body in the glass or plastic mold, the cladding body being
provided with the structured forming surface of the forming
tool,
[0014] c) releasing the cladding body with the structured forming
surface from the glass or plastic mold; and
[0015] d) bonding the cladding body to a base body with a
non-structured surface thereof in contact with the base body to
form the finally shaped forming tool with the forming surface.
[0016] A finally shaped forming tool according to the invention can
be manufactured comparatively economically both with the required
geometric shape and surface quality, especially the surface
roughness and structuring. At the same time uniform structural
properties are obtained.
[0017] These methods can produce layered systems or material
gradients and three dimensional structures in the .mu.m-range on
the working surfaces besides processing an exceptionally large
number of material compositions, including metallic materials and
also ceramic materials.
[0018] These advantages are present, particularly when thermal
spraying technology is used to provide the negative coating on the
negative mold. Other coating technologies can also be utilized.
[0019] According to various embodiments of the method according to
the invention the negative mold is a plastic body structured by
means of lithography methods.
[0020] In other embodiments mechanical methods or methods based on
thermal principles are used to structure the negative mold.
[0021] The thermal spraying occurs according to a first embodiment
of the invention preferably by flame spraying methods, especially
by a HVOF method. This method permits a layer structure with a high
structural uniformity.
[0022] A second embodiment of the process according to the
invention, in which the thermal spraying comprises plasma spraying,
also provides this latter advantage. The preferred plasma spraying
method is a VPS or LPPS method. These methods have the additional
advantage that a wide range of materials, especially hard alloys
and hard materials, such as carbides, can be sprayed.
[0023] The foregoing methods permit the spraying of both
single-phase materials and also material combinations, in order to
form layered systems or material gradients. Thus in the method
according to the invention the materials for the structured forming
surface of the forming tool can be adjusted in a simple way.
[0024] The above-described methods permit a predetermined coating
thickness to be applied to the negative mold. This coating
thickness is selected so that the coating body released from the
negative mold can be bonded with the supporting material or body of
the forming tool.
[0025] When the coating thickness according to a first embodiment
is from 100 .mu.m to 5 mm, the manufacture of the forming body is
performed, preferably so that the coating or cladding body released
from the negative mold is bonded with another material as part of a
HIP capsule by an HIP method to make the forming tool. These
methods guarantee a permanent intimate material bond between the
separately made structured coating or cladding body and the base or
supporting material of the forming tool.
[0026] When the coating thickness is sufficiently large, up to 20
mm, the cladding body can be used directly to provide the forming
surface of the forming tool, since the cladding body released from
the negative mold can be combined mechanically with a based body to
form the forming tool.
[0027] A first layer made by thermal spraying can be reinforced or
built up by bonding to a large layer thickness, which speeds up the
making of thick coatings.
[0028] In regard to the finally shaped forming tool with the
structured forming surface of high structural uniformity the
above-described objects of the invention are attained by a
structured forming surface, which is formed by a separately
produced coating body or cladding body made by thermal spraying,
which is bonded with supporting material to form the forming
tool.
[0029] The forming tool should be structured so that the separately
produced coating body has a thickness of up to 20 mm and is
mechanically bonded with the supporting material, or so that the
separately produced cladding body has a thickness of from 500 .mu.m
to 5 mm and is a part of a HIP capsule, which is bonded, connected
or attached by means of an HIP method with the base material.
BRIEF DESCRIPTION OF THE DRAWING
[0030] The objects, features and advantages of the invention will
now be illustrated in more detail with the aid of the following
description of the preferred embodiments, with reference to the
accompanying figures in which:
[0031] FIG. 1 is a schematic longitudinal cross-sectional view
through a mold acting as a pattern for the later-formed forming
tool, in which the negative of the structure of the later-formed
forming tool is incorporated,
[0032] FIG. 2 is a schematic longitudinal cross-sectional view
illustrating the step of making a coating or cladding body in the
mold shown in FIG. 1 with a given material by thermal spraying
methods,
[0033] FIG. 3 is a schematic longitudinal cross-sectional view
showing the mechanical attachment of the cladding body released
from the mold with a based body to form a forming tool, and
[0034] FIG. 4 is a schematic longitudinal cross-sectional view
showing the bonding of the cladding body or coating released from
the mold in a HIP capsule by means of a HIP process with a base
and/or supporting material to form the forming tool.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] A preferred embodiment of the method for making a finally
shaped forming tool with a structured forming surface, which
guarantees a very high uniformity of the surface structure, is
illustrated in the drawing.
[0036] In a first step shown in FIG. 1 a mold 1 is provided having
a pattern for forming the forming tool with the structured surface,
i.e. the mold 1 has a negative shape corresponding to the
structured surface of the forming tool to be made. In order to
simplify the illustration of the mold and the corresponding forming
body the mold is shown with only a comparatively simple surface
structure including a straight section 1a and two curved sections
1b separated from the straight section 1a by two cavities 1c.
[0037] In the case of actual embodiments of the forming tool the
negative structure of the mold is worked according to the surface
structure of the forming tool to be made. The dimensions of the
negative structure in the mold must be guided by dimensions, which
depend on the forming process performed with the later-formed
forming tool. In the hot-forming the dimensions of the surface
structure of the forming tool change, for example, because of the
unavoidable thermal expansion occurring during the hot-forming
process, which must be taken into consideration in selection of the
dimensions for the negative structure of the mold according to FIG.
1.
[0038] The making of the negative mold 1 can occur in different
ways. One way is the so-called prototyping. In this method the
negative mold with the desired geometric contour/structure is made
by means of lithography methods (mask engineering in connection
with photo lacquer) from a plastic body and the required surface
quality is guaranteed. These lithography methods are basically
known and need not be explained in further detail.
[0039] Another method for making the forming tool consists in
grinding, sandblasting, machining or structuring with methods that
operate by thermal action principles, such as erosion or laser
machining so that a base body is provided with the negative
structure of the forming tool.
[0040] In the following process step shown in FIG. 2 the negative
mold 1, preferably coated by means of thermal spraying technology,
is provided with a coating 2 of a predetermined thickness as
indicated by the arrows in FIG. 2.
[0041] Thermal spraying methods include flame spraying, electric
arc spraying, plasma spraying and special spraying methods, such as
detonation coating and condensation spraying. These methods are
also known basically and do not need to be explained further
herein. The plasma spraying is particularly significant for the
present application, because of the high quality of the coating
formed by it, especially in regard to uniformity, and because the
method permits the processing of high melting metallic and ceramic
materials, which are required in the structuring of glass on
account of the required heat and corrosion resistance. Alloys of
nickel/chromium, cobalt-based alloys and carbides are included in
these materials.
[0042] The so-called HVOF method (high velocity oxide fuel flame
spraying) in flame spraying and the so-called VPS method (vacuum
plasma spraying) or the LPPS method (low pressure plasma spraying)
in plasma spraying have special significance. Surfaces having very
slight porosity and high uniformity are obtained immediately in
these processes.
[0043] The effectiveness of the process of thermal spraying depends
in a known way decisively on the parameters of the process during
coating, here of the negative mold 1. Those parameters are, for
example, the carrier gas supply, the spacing of the burner nozzle
from the negative mold, the temperature, etc. These parameters are
varied according to the material to be sprayed and the desired
geometry of the negative mold. They are determined in the case of
particular embodiments by one skilled in the art.
[0044] A coating 2 made from a predetermined material with a
predetermined thickness is provided on the negative mold 1 at the
end of the thermal spraying step, which has the desired finally
shaped structure in regard to geometry and surface quality with the
high structural uniformity on the contacting surface of the
negative mold.
[0045] This coating 2 is removed from the negative mold 1 to make
the forming tool. The release of the coating 2 can be made easy by
suitable pre-treatment of the surface of the negative mold 1 to be
coated prior to the coating.
[0046] The released coating 2 can then be processed in different
ways for forming the surface structure of the forming tool.
[0047] According to a first possibility the coating can be formed
so thick, about 1 to 20 mm, that the outer shape of the outer layer
of the forming tool is obtained as a coating or cladding body.
After release from the mold 1 this cladding body, as shown in FIG.
3, can be clamped on the base body 3 for the forming tool, e.g. by
a suitable die, in order to provide a mechanically stable forming
tool.
[0048] According to another possibility a coating 2 with a
thickness of about 1 to 5 mm is produced. This coating is released
from the negative mold, as shown in FIG. 4, to form a part of an
HIP capsule 4, which is filled with a powder for pressing, if
necessary in connection with an embedded solid material or body.
The thickness of the coating body 2 forming the part of the HIP
capsule should be larger than, for example at least twice as large
as, that of the remaining capsule half. The shrinking or changing
of the surface can be prevented because of that feature. Only the
edges are warped or twisted by the HIP process.
[0049] A working device forming the forming tool is available in
which the coating body 2 provides a structuring surface, which
comes into working contact, e.g., with the glass or plastic
substrate and which has the negative of the structure to be formed
on its surface after performing the above-described HIP method,
alternatively also after a bonding process. The negative
structuring surface of the forming tool comprises a straight
section 2a, the two curved sections 2b and the raised structures
2c.
[0050] Instead of the coating consisting of only a single layer of
material the coating 2 can be made up of several layers of
different materials applied one over the other. Also several
materials can be simultaneously sprayed to form the coating.
[0051] Preferably the sprayed coating body is sealed by a
subsequent HIP process.
[0052] The disclosure in German Patent Application 100 34 508.5-16
of Jul. 15, 2000 is incorporated here by reference. This German
Patent Application describes the invention described hereinabove
and claimed in the claims appended hereinbelow and provides the
basis for a claim of priority for the instant invention under 35
U.S.C. 119.
[0053] The wording "surface corresponding to the negative of the
structure to be provided in the glass or plastic substrate" means
simply that the surface is shaped or structured so as to produce
the article from the glass or plastic substrate with a desired or
predetermined shape.
[0054] The term "negative mold" for the forming tool means that the
mold is shaped with a surface contacting the forming tool during
the molding which is the negative of the surface formed on the
forming tool, i.e. the mold is shaped to produce the desired
predetermined surface on the forming tool. Of course during the
molding this means that there are no gaps or spaces between the
structuring surface on the forming tool and the contacting surface
of the mold. This is the usual situation for a mold and an article
molded by means of the mold.
[0055] While the invention has been illustrated and described as
embodied in an end-contoured shaping forming tool with a forming
surface and method of forming same, it is not intended to be
limited to the details shown, since various modifications and
changes may be made without departing in any way from the spirit of
the present invention.
[0056] Without further analysis, the foregoing will so fully reveal
the gist of the present invention that others can, by applying
current knowledge, readily adapt it for various applications
without omitting features that, from the standpoint of prior art,
fairly constitute essential characteristics of the generic or
specific aspects of this invention.
[0057] What is claimed is new and is set forth in the following
appended claims.
* * * * *