U.S. patent application number 11/179225 was filed with the patent office on 2005-11-10 for method for manufacturing a mold core coating.
This patent application is currently assigned to IMI NORGREN, INC.. Invention is credited to Flynn, Robert William.
Application Number | 20050247426 11/179225 |
Document ID | / |
Family ID | 31992430 |
Filed Date | 2005-11-10 |
United States Patent
Application |
20050247426 |
Kind Code |
A1 |
Flynn, Robert William |
November 10, 2005 |
Method for manufacturing a mold core coating
Abstract
A mold construction is provided having a layered configuration
including a substrate or mold core preferably of ampcoloy, an
intermediate or primer coat preferably of electroless nickel, and
an outer mold surface layer made of a high strength metal
preferably of titanium. The mold construction is particularly
advantageous for use in molding glass objects. The electroless
nickel undercoat or primer coat serve to adhere the softer ampcoloy
substrate to the high strength outer layer of titanium alloy. The
electroless nickel also provides some elasticity for the outer
layer of titanium alloy layer to reduce cracking and flaking of the
titanium alloy. The layer of titanium alloy provides good strength
and durability to withstand abrasive contact with the molten glass,
while the ampcoloy still facilitates high thermal conductivity for
reducing mold cycle times.
Inventors: |
Flynn, Robert William;
(Littleton, CO) |
Correspondence
Address: |
SETTER OLLILA, LLC
2060 BROADWAY
SUITE 300
BOULDER
CO
80302
US
|
Assignee: |
IMI NORGREN, INC.
|
Family ID: |
31992430 |
Appl. No.: |
11/179225 |
Filed: |
July 12, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11179225 |
Jul 12, 2005 |
|
|
|
10247109 |
Sep 18, 2002 |
|
|
|
Current U.S.
Class: |
164/98 ; 164/138;
164/369 |
Current CPC
Class: |
C23C 28/321 20130101;
C03B 2215/11 20130101; C03B 2215/22 20130101; C03B 2215/32
20130101; B29C 33/76 20130101; B29C 33/38 20130101; C03B 11/086
20130101; C23C 28/34 20130101 |
Class at
Publication: |
164/098 ;
164/138; 164/369 |
International
Class: |
B22D 019/08; B22C
009/10 |
Claims
1. A method of manufacturing a mold, said method comprising the
steps of: creating a mold core of a desired shape to confirm to a
shape of an article to be molded, said mold core being made of a
copy based alloy; applying a primer coating of an electroless
nickel over the mod core at a desired thickness; and applying an
outer layer of a titanium alloy over the primer coating at a
desired thickness, wherein the primer coating adequately binds the
mold core and the outer layer.
2. A method, as claimed in claim 1, wherein: said first applying
step is achieved by an auto-catalytic process.
3. A method, as claimed in claim 1, wherein: said second applying
step is achieved by vapor deposition.
4. A method, as claimed in claim 1, wherein: said copper based
alloy includes ampcoloy.
5. A method, as claimed in claim 1, wherein: said titanium alloy is
selected from the group consisting of titanium nitride, titanium
carbon nitride, chromium nitride, chromium carbide, and titanium
carbide/carbon.
6. A method, as claimed in claim 1, wherein: said primer coating is
applied at a range of thickness of between 0.0001 and 0.005 of an
inch thick.
7. A method, as claimed in claim 1, wherein: said titanium alloy is
applied at a range of thickness between 0.0001 to 0.0003 of an inch
thick.
Description
RELATED APPLICATIONS
[0001] This application is a divisional from co-pending application
Ser. No. 10/247,109 entitled, "Mold Core Coating" filed Sep. 18,
2002, which is hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] This invention relates to the manufacture of molds and, more
particularly, to a mold construction including a layered coating
especially adapted for molding of glass material, and a method
relating to the manufacture of such a mold.
BACKGROUND OF THE INVENTION
[0003] Various types of molds have long been used for preparing
shaped articles made from a wide range of materials such as
thermoplastic resins, glass, and other materials which can be
placed in a molten form for injection or compression within a mold.
Some of the different types of molding processes include blow
molding, compression molding, injection molding, and injection
compression molding. Molds for these types of processes are
typically manufactured from metal having high thermal
conductivity.
[0004] Blow molding involves the extrusion of a molten robe of
resin called a parison into a mold. The mold closes around the
parison, pinching the bottom of the parison closed. A gas such as
air is then introduced causing the tube to expand against the
cooled surfaces of the mold.
[0005] In compression molding, composite blanks of glass reinforced
thermoplastic sheets are heated. The material is heated above its
melting point, or if an amorphous material is used, at least
substantially above its glass transition temperature. When the
composite blanks are heated, they expand due to the recoil forces
within the fibers. The hot blanks are then pressed between cool
mold surfaces which are below the melting point or glass transition
temperature.
[0006] Injection molding involves the injection of molten
thermoplastic resin into a mold apparatus. Molds for injection
molding of thermoplastic resin are usually made from a metal such
as iron, steel, stainless steel, aluminum alloy, or brass. These
materials are particularly advantageous because they have high
thermal conductivity, thus allowing the melt of the thermoplastic
resin to cool rapidly, thereby shortening the molding cycle
time.
[0007] For injection compression molding, this is a combined
process wherein a hot thermoplastic melt is injected into a mold
cavity. The parting line of the mold is placed in an open position,
or is allowed to be forced open by the injected melt. The clamping
force is increased initiating the compression stroke of the mold,
forcing the melt to fill the cavity. In many instances, the
velocity of the melt front through the cavity changes as the
injection stroke stops and the compression stroke begins.
[0008] In each of the above described processes, there are certain
disadvantages associated with a fast cooling resin during the
molding operation. For example, in injection molding, cooling of
the injected material at too rapid of a rate causes the injected
resin to freeze instantaneously at the mold surface, thus creating
a thin solid layer which restricts the flow of the molten material
through the remaining cavity portions of the mold.
[0009] In order to slow down the rate at which the injected
material cools, multi-layer mold constructions have been developed
wherein a metal core has an insulated layer bonded thereto which
slows the initial cooling of the resin during the molding
operation. Accordingly, the insulating layer is typically made of a
material having low thermal conductivity, yet also having good
resistance to high temperature degradation, thereby permitting the
mold to be used in repeated high temperature cycles. Resinous
insulating layers have a major disadvantage in that they are not
mechanically strong and are easily abraded upon contact. Insulating
layers made of a resin material may also suffer from creating
molded articles having surface imperfections. Furthermore, molds
which include resinous insulating layers are not adapted for
molding glass, as the glass may have a hardness which would destroy
the insulating layer.
[0010] It is also known to place one or more skin layers of hard
material, typically metal, bonded to the insulating layer. Skin
layers may be deposited by such operations as electroless
deposition, electrolytic deposition and combinations thereof.
However, such deposition operations introduce their own problems
into the mold fabricating process. It is well known, or example,
that some metal layers do not adhere well to resinous substrates.
Thus, the metal skin layers suffer from cracking.
[0011] One example of a reference which discloses a multi-layer
injection mold includes the U.S. Pat. No. 5,535,980. This reference
discloses a mold construction including an insulating layer
preferably of resin that is deposited on a metal core. A second
layer comprising a metal which is suspended in another layer of
resin is deposited upon the insulating layer. The second layer may
contain metal in platelet form, or may contain the metal in other
forms such as fiber or irregular whisker shapes.
[0012] U.S. Pat. No. 5,124,192 discloses a mold for use in
producing plastic parts wherein the mold includes a multi-layered
core structure. A number of different types of metals are
disclosed, to include nickel which may be used as a-skin layer as
well as in an insulation layer.
[0013] U.S. Pat. No. 5,641,448 discloses a method for making molds
used for producing prototype plastic parts. In the preferred
embodiment, the mold core is shown as including an outer shell or
skin of electroless nickel.
[0014] One particularly advantageous material for use in mold
construction which has extremely high thermal conductivity,
therefore allowing a high rate of heat transfer from the molten
material through the mold core, is a material known as ampcoloy.
Ampcoloy is an alloy manufactured by Ampco Metal of Marly,
Switzerland. U.S. Pat. Nos. 5,376,317; 6,290,882; and 6,352,1426
each disclose the use of ampcoloy within mold constructions.
Ampcoloy is a copper based alloy, which may also include minor
compositions of beryllium, cobalt, and/or nickel. Although ampcoloy
has outstanding conductivity for reducing mold cycle times,
ampcoloy has a relatively low hardness. Therefore, ampcoloy is not
adequate for molding glass.
[0015] It is also generally known to place various types of
coatings on industrial parts in order to increase lubricity,
corrosion resistance, and wear life. However, one particular
drawback with many of these coatings is the inability for the
coatings to adequately adhere to metallic substrates, as well as
the inability of such coatings to withstand repeated heating
cycles, such as encountered in molding processes.
[0016] Although the foregoing prior art may be adequate for its
intended purposes, there still remains a need for a mold
construction wherein high thermal conductivity of the mold is
maintained for purposes of reducing cycle time; but the mold is of
a durable and mechanically strong construction so that materials
such as glass may be molded without damage occurring to the contact
surfaces of the mold.
SUMMARY OF THE INVENTION
[0017] The present invention in one aspect is a new mold
construction which utilizes a multiple layer approach for providing
desired thermal conductivity and durability. The mold core
construction comprises a substrate or mold core made of an alloy
such as ampcoloy. An electroless nickel coating is applied to the
ampcoloy. Then, another metal layer or coating is applied over the
electroless nickel in the form of a high strength metal, such as
Futura.TM.. Futura.TM. is a titanium alloy comprising minor
compositions of aluminum, thereby forming a titanium nitride
coating. Futura.TM. is manufactured by Balzers of Balzers,
Liechtenstein.
[0018] Use of the ampcoloy provides reduced cycle time, and the
ampcoloy is protected by the overcoating of the titanium alloy,
which can withstand the abrasive nature of glass molding. The
electroless nickel acts as a primer coating wherein the electroless
nickel serves to adequately bond the ampcoloy and the titanium
alloy.
[0019] Ampcoloy, as well as many titanium based alloys, have poor
adhesion characteristics making them more difficult to use in
combination with other mold layers. Electroless nickel exhibits
good adhesion characteristics which allows the nickel to act as a
primer coat for adequately bonding the titanium alloy to the mold
core of ampcoloy. Therefore, in another aspect of the invention, a
novel primer coating is provided in the form of an electroless
nickel which is situated between a mold core layer and an exposed
mold surface layer made of a higher strength metal.
[0020] Further advantages of the invention will become apparent
from a review of the following figure, taken along with the
accompanying detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a simplified schematic diagram illustrating a
cross-section of a mold constructed in accordance with the present
invention.
DETAILED DESCRIPTION
[0022] The present invention relates to a new mold construction,
and a method of mold manufacture wherein the mold construction
comprises three primary layers or constituents. The mold includes a
substrate or mold core made of a high thermal conductive material
such as ampcoloy, an exposed mold surface made of a high strength
metal such as titanium, and a bonding or primer coating of
electroless nickel which adequately adheres the high strength
titanium coating to the softer ampcoloy core.
[0023] One example of a manufacturer of electroless nickel includes
Armoloy of Decalb, Illinois. A preferred electroless nickel coating
contains about 5-15% of phosphorous. Electroless nickel in the form
of a high nickel/low phosphorous alloy deposited by chemical
reduction without electrical current is a more corrosion resistant
solution than electroplated nickel. On properly prepared
substrates, electroless nickel is typically free of pores and other
surface abnormalities. Electroless nickel deposits can also be
evenly distributed over surfaces of even complex parts.
Accordingly, total thickness of an electroless nickel deposit can
be reduced, thus allowing close tolerances to be maintained.
Electroless nickel has sufficient hardness, lubricity, wear
resistance, and uniform deposit thickness which makes it an ideal
material to be used as a primer or undercoat for the exposed mold
layer of high strength titanium alloy. Electroless nickel coatings
surpass most MIL spec standards for bend tests without any
indications of flaking or other surface failures. Even if cracking
of the electroless nickel coat occurs, the cracking is not
typically accompanied by flaking, demonstrating that the adhesion
of the electroless nickel primer is well suited for mold
construction.
[0024] The titanium alloy which may be used in the mold
construction of the present invention, as discussed above, may be
made of a material known as Futura.TM. titanium aluminum nitride.
Other acceptable coatings include other high strength titanium
alloys, such as titanium nitride, titanium carbon nitride, chromium
nitride, chromium carbide, and titanium carbide/carbon. Each of
these alloys are sold under the trademark Balinit.RTM. of
Balzers.
[0025] Various types of ampcoloy are available from Ampco Metal, to
include a group of ampcoloy products sold under the trademark
MoldMate.TM.. Specifically, acceptable ampcoloy types include
MoldMate.TM. 18, 90, 97, 940, 21w and 22w. In testing, MoldMate.TM.
90 and 940 have been found to be particularly effective. For each
of these alloys, they comprise primarily a balance of copper and a
small percentage of other metals to include beryllium or
cobalt.
[0026] Now referring to FIG. 1, a representative sample of a
cross-section of a mold in accordance with the current invention is
shown. This Figure is not to scale in order to visualize the three
layers of the mold construction. In practice, the electroless alloy
coatings are of such thickness that they would be difficult to view
with the unaided eye. A substrate or mold core layer of ampcoloy 12
is provided in the shape of the article to be molded. The core
layer 12 can be any shape depending upon the shape of the article
to be molded. A primer or undercoat of electroless nickel 14 is
deposited over the ampcoloy substrate. Preferably, the electroless
nickel is deposited by an auto-catalytic process (such as a
submerged bath). Preferably, the electroless nickel is applied with
a thickness of three ten thousands of an inch (0.0003). A titanium
alloy 16 such as Futura.TM. is then deposited over the electroless
nickel layer.
[0027] Preferably, the titanium coating is also applied at
approximately three ten thousands of an inch thick (0.0003). The
titanium coating may be applied by known vapor deposition
processes.
[0028] For the electroless nickel, an acceptable range of the
thickness would be 0.0001 of an inch to 0.005 of an inch. For
Futura.TM. or other Balinit.RTM. products, an acceptable range of
thickness would be 0.0001 to 0.0003 of an inch.
[0029] Although the electroless nickel and titanium coatings are
placed over the ampcoloy, these coatings do not significantly
degrade the high thermal conductivity of the ampcoloy because these
coatings can be applied in extremely thin layers.
[0030] Because the electroless nickel coating is appreciably softer
than the titanium coating, the electroless nickel also provides
some give or elasticity, therefore enhancing the ability of the
titanium overcoat to better withstand shock. Thus, the electroless
nickel undercoating helps to absorb the shock thereby preventing
flaking or cracking of the titanium overcoat.
[0031] By the foregoing, a mold construction is provided wherein a
mold cycle time may be minimized, yet the type of material which
may be molded includes hard material such as glass. The high
strength layer of titanium is resistant to abrasion or other damage
by the material to be molded. The intermediate or primer coating of
electroless nickel allows the hard exposed coating of titanium to
adhere well to the ampcoloy substrate. Furthermore, the electroless
nickel primer provides some give or elasticity in relation to the
titanium overcoat, thereby reducing cracking or flaking of the
titanium overcoat. The overall mold construction is very durable,
and is particularly adapted for molding of glass material.
[0032] Although the mold construction and method of the present
invention is particularly suited for molding glass, the invention
is generally suited for many other types of materials such as
thermoplastic resins used in injection molding.
[0033] The foregoing invention has been described with respect to a
preferred embodiment; however, various changes and modifications
may be made which fail within the spirit and scope of the
invention.
* * * * *