U.S. patent application number 11/414601 was filed with the patent office on 2007-03-22 for method for molding products made from metal or plastic materials.
This patent application is currently assigned to HON HAI Precision Industry CO., LTD.. Invention is credited to Ga-Lane Chen.
Application Number | 20070062665 11/414601 |
Document ID | / |
Family ID | 37878074 |
Filed Date | 2007-03-22 |
United States Patent
Application |
20070062665 |
Kind Code |
A1 |
Chen; Ga-Lane |
March 22, 2007 |
Method for molding products made from metal or plastic
materials
Abstract
A method for molding products made from metal materials is
provided, which includes the following steps: heating a metal
material to a melting temperature; and quenching the metal material
from the melting temperature to a quenching temperature. The
quenching temperature being 5.about.20 degrees centigrade lower
than room temperature. A method for molding products made from
plastic materials is also provided, which includes the following
steps: heating a plastic material to a melting temperature;
decreasing temperature from the melting temperature to a glass
transition temperature of the plastic material; quenching the
plastic material from the glass transition temperature to a
quenching temperature, with the quenching temperature being
5.about.20 degrees centigrade lower than room temperature;
tempering the plastic material from the quenching temperature to a
tempering temperature; and decreasing temperature from tempering
temperature to room temperature.
Inventors: |
Chen; Ga-Lane; (Fremont,
CA) |
Correspondence
Address: |
PCE INDUSTRY, INC.;ATT. CHENG-JU CHIANG JEFFREY T. KNAPP
458 E. LAMBERT ROAD
FULLERTON
CA
92835
US
|
Assignee: |
HON HAI Precision Industry CO.,
LTD.
Tu-Chen City
TW
|
Family ID: |
37878074 |
Appl. No.: |
11/414601 |
Filed: |
April 28, 2006 |
Current U.S.
Class: |
164/122 ;
164/128 |
Current CPC
Class: |
B22D 27/04 20130101 |
Class at
Publication: |
164/122 ;
164/128 |
International
Class: |
B22D 27/04 20060101
B22D027/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 16, 2005 |
CN |
200510037359.7 |
Claims
1. A method for molding products made from metal materials
comprises the following steps: heating a metal material to a
melting temperature; and quenching the metal material from the
melting temperature to a quenching temperature, with the quenching
temperature being 5.about.20 degrees centigrade lower than room
temperature.
2. The method as claimed in claim 1, wherein a quenching rate of
quenching step is 5.about.100 degrees centigrade per second.
3. The method as claimed in claim 2, wherein the quenching rate is
20.about.50 degrees centigrade per second.
4. The method as claimed in claim 1, wherein the metal materials
are chosen from the following group: aluminium magnesium alloy,
magnesium aluminium alloy, aluminium magnesium titanium alloy,
aluminium magnesium chromium alloy, iron carbon alloy, stainless
steel, magnesium alloy and titanium molybdenum alloy.
5. The method as claimed in claim 4, wherein the metal materials
further comprises nano luminous materials, chosen from the
following group: ZnS, CdSe, CdS, Eu--ZnSiO.sub.x, Eu--YBO.sub.3 and
Eu--BaMgAlO.sub.x.
6. A method for molding products made from plastic materials
comprises the following steps: heating a plastic material to a
melting temperature; decreasing the temperature from the melting
temperature to a glass transition temperature of the plastic
material; quenching the plastic material from the glass transition
temperature to a quenching temperature, with the quenching
temperature being 5.about.20 degrees centigrade lower than room
temperature; tempering the plastic material from the quenching
temperature to a tempering temperature; and decreasing temperature
from tempering temperature to room temperature.
7. The method as claimed in claim 6, wherein a quenching rate from
glass transition temperature to the quenching temperature is
5.about.100 degrees centigrade per second.
8. The method as claimed in claim 7, wherein the quenching rate is
20.about.50 degrees centigrade per second.
9. The method as claimed in claim 6, wherein the tempering
temperature is 80.about.100 degrees centigrade.
10. The method as claimed in claim 6, wherein a tempering rate from
the quenching temperature to the tempering temperature is
5.about.80 degrees centigrade per second.
11. The method as claimed in claim 10, wherein the tempering rate
is 20.about.50 degrees centigrade per second.
12. The method as claimed in claim 6, further comprising a step of
processing a dwell step for 10 seconds after decreasing to the
glass transition temperature.
13. The method as claimed in claim 6, wherein after decreasing to
quenching temperature, maintain temperature at the quenching
temperature for 10.about.20 seconds.
14. The method as claimed in claim 6, wherein when rising to
tempering temperature, maintain temperature at the tempering
temperature for 20.about.60 seconds.
15. The method as claimed in claim 6, wherein the plastic materials
are ABS resin added with glass fiber.
16. The method as claimed in claim 1, wherein during quenching step
and/or tempering step, inert gases are introduced.
17. The method as claimed in claim 6, wherein during quenching step
and/or tempering step, inert gases are introduced.
Description
TECHNICAL FIELD
[0001] The present invention relates to methods for molding
products, in particular, to a method for molding products made from
metal or plastic materials.
BACKGROUND
[0002] With the great development of technologies, market
competition in the field of consumer electronic products becomes
furious. For manufacturers, in order to sell out their products,
efforts have been focused not only on functions of the products,
but also on appearance of the products.
[0003] A shell of commonly used consumer electronic products is
often made of metal or plastic materials. Shells with crude and
tarnished surface will affect the appearance of the products. In
addition, since shells are often touched by customers' hands, wear
resistant properties are important to influence the appearance.
Besides, impact resistant properties of shells are also important,
which can prevent the appearance of the products from being
destroyed by sudden impact or fall.
[0004] To improve surface properties of shells, particular
treatment should be provided. Typically, heat treatments, such as
quenching or tempering are widely used. While, during quenching,
the shell will be naturally cooled down to room temperature. Sizes
of crystal grains of the shells formed therefrom usually become
large, whereby the surfaces of the shells become rough. This will
not only influence brightness and smoothness of the surface, but
also affect the toughness of the shell.
[0005] Therefore, a heretofore-unaddressed need exists in the
industry to address the aforementioned deficiencies and
inadequacies.
SUMMARY
[0006] In a first preferred embodiment, a method for molding
products made from metal materials includes the following steps:
heating a metal material to a melting temperature; and quenching
the metal material from the melting temperature to a quenching
temperature. The quenching temperature is 5.about.20 degrees
centigrade lower than room temperature.
[0007] In a second preferred embodiment, a method for molding
products made from plastic materials includes the following steps:
heating a plastic material to a melting temperature; decreasing the
temperature from the melting temperature to a glass transition
temperature of the plastic material; quenching the plastic material
from the glass transition temperature to a quenching temperature;
tempering the plastic material from the quenching temperature to a
tempering temperature; and decreasing the temperature from the
tempering temperature to room temperature. The quenching
temperature is 5.about.20 degrees centigrade lower than room
temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Many aspects of the molding methods can be better understood
with reference to the following drawings.
[0009] FIG. 1 is a temperature--time graph of a method for molding
products made from metals of a first preferred embodiment;
[0010] FIG. 2 is a flow chart of the method of FIG. 1;
[0011] FIG. 3 is a temperature--time graph of a method for molding
products made from plastics of a second preferred embodiment;
and
[0012] FIG. 4 is a flow chart of the method of FIG. 3.
DETAILED DESCRIPTION
[0013] A method of a first preferred embodiment is used for molding
a metal shell. During dead-end molding step, temperature alteration
of the metal shell should be controlled strictly as the method
described, so as to get improved mechanical properties on a surface
layer of metal products. Referring to FIGS. 1 and 2, T.sub.1
represents a melting temperature of the metal. T.sub.R represents
room temperature. T.sub.q represents a quenching temperature. First
of all, when a metal shell raw product is made, metal material on
surface layer of the metal shell row product is heated to the
melting temperature (T.sub.1) thereof. After maintaining the
temperature at the melting temperature (T.sub.1) for 10.about.20
seconds, the melted metal is quenched rapidly from the melting
temperature (T.sub.1) to the quenching temperature (T.sub.q). The
quenching temperature (T.sub.q) is 5.about.20 degrees centigrade
lower than room temperature (T.sub.R). During this process,
quenching rate from the melting temperature to the quenching
temperature should be controlled fast, normally at a rate of
5.about.100 degrees centigrade per second, preferably 20.about.50
degrees centigrade per second. In order to prevent the metal shell
from crisp, it is preferable to maintain the temperature at the
quenching temperature for a long time, e.g., for about half-hour.
Thus, finished metal product is manufactured.
[0014] During this process, the metal shell is treated with rapid
quenching technology. Since the quenching rate is fast, and the
quenching temperature is lower than room temperature, there's no
time for grains of the metal material growing by diffusion
mechanism. Thus sizes of crystal grains of the metals will be
reduced, surface roughness will be decreased and brightness will be
enhanced. Accordingly, compared with nature cooling process, the
quenching process of the preferred embodiment could get a smaller
grain size.
[0015] The metal materials which are suitable to the above rapid
quenching process is selected from the following group comprising
of aluminium magnesium alloy, magnesium aluminium alloy, aluminium
magnesium titanium alloy, aluminium magnesium chromium alloy, iron
carbon alloy, stainless steel, magnesium alloy and titanium
molybdenum alloy.
[0016] A method of a second preferred embodiment is used for
molding plastic shell, before a injection molding step. This method
includes the following steps: heating a plastic material to a
melting temperature thereof; decreasing the temperature from the
melting temperature to a glass transition temperature thereof;
dwelling or keeping pressure at the glass transition temperature;
quenching the plastic material from the glass transition
temperature to a quenching temperature; first heat insulating or
keeping temperature at the quenching temperature; tempering the
plastic material from the quenching temperature to a tempering
temperature; second heat insulating at the tempering temperature;
and decreasing the temperature from the tempering temperature to
room temperature. Referring to FIGS. 3 and 4, T.sub.2 represents
the glass transition temperature of the plastic. T.sub.R represents
room temperature. T.sub.q represents the quenching temperature.
T.sub.a represents the tempering temperature.
[0017] When manufacturing, plastic particles are firstly fed into a
chamber of an injection-molding machine, and then heated to melt at
a melting temperature. The melting temperature of a plastic is
normally about 300 degrees centigrade, at which the plastic is
flowable. Thus the melted plastics can flow from the chamber to a
runner, and then into a cavity. When the cavity is filled with
melted plastic material, decreasing the temperature from the
melting temperature to the glass transition temperature (T.sub.2)
of the plastic material. During that step, the plastic material
changes from a glassy state to a rubbery state. To different
plastics, the melting temperature and the glass transition
temperature are different. The glass transition temperature of
plastics is normally about 100 degrees centigrade. In order to
prevent plastic material from strong shrinkage due to sudden
quencher, a dwell step is preferred, during that step, at the glass
transition temperature, pressure in the cavity is maintained for
about 10 seconds, referring to the first straight line in FIG. 2.
Then quenching the glassy stated plastic material rapidly from the
glass transition temperature (T.sub.2) to the quenching temperature
(T.sub.q) at a quenching rate of 5.about.100 degrees centigrade per
second, preferably 2.about.50 degrees centigrade per second. The
quenching temperature is 5.about.20 degrees centigrade lower than
room temperature (T.sub.R).
[0018] After maintaining temperature at the quenching temperature
(T.sub.q) for 10.about.20 seconds, the plastic material undergoes a
tempering step, that is, the temperature rises rapidly from the
quenching temperature (T.sub.q) to a tempering temperature
(T.sub.a) with a rising rate of 5.about.80 degrees centigrade per
second, preferably 10.about.40 degrees centigrade per second. And
then after maintaining temperature at the tempering temperature for
20.about.60 seconds, the temperature is decreased rapidly to room
temperature at a decreasing rate of 10.about.20 degrees centigrade
per second. Finally, followed with a rejection molding process, a
plastic shell is formed.
[0019] Furthermore, in order to prevent melted plastic material
from oxidating, during rapid quenching step and/or rapid tempering
step, protective gases are introduced, which could be chosen from
inert gases, such as nitrogen, argon or helium.
[0020] The plastic materials could be a composite material, such as
a acrylonitrile butadiene styrene (ABS) resin added with
fiberglass. The plastic could be used in mobile phone, notebook,
desktop computer, DVD, liquid crystal display et al.
[0021] During molding of products made of metal or plastic
materials, a rapid quenching process and/or a rapid tempering
process are applied. Since the quenching rate is fast, quenching
temperature is lower than room temperature, there is no time for
the sizes of crystal grains of plastics growing at a diffusion
mechanism. Thus sizes of crystal grains of the plastics will be
reduced, furthermore, brightness, smoothness and surface toughness
will be enhanced.
[0022] For metal alloy or plastic, particle size is an important
factor which can affect fracture toughness of the materials.
Fracture toughness (K.sub.1c) is one of main mechanical parameters
for metal alloy or plastic. Fracture toughness indicates an ability
of the material for preventing micro crack extension. Generally,
when the fracture toughness is high, the material exhibits a good
mechanical property. The fracture toughness satisfies the following
formula: K 1 .times. c ~ .sigma. y ( 3.14159 .times. c d ) 0.5
##EQU1## wherein K.sub.1c represents fracture toughnesss;
.sigma..sub.y represents yield strength, also known as yield limit;
c represents crack length; and d represents particle size. It can
be deducted from the above formula that the smaller the particle
size, the larger the fracture toughness. Thus, when quenching at
the temperature of lower than room temperature, sizes of crystal
grains are reduced, thus fracture toughness will be enhanced.
[0023] In order to further improve the brightness of the shells
made from metals or plastics, phosphorus or nano luminous materials
could be added into the metals or the plastics. These nano luminous
materials could be chosen from the following: ZnS, CdSe, CdS,
Eu--ZnSiO.sub.x, Eu--YBO.sub.3 and Eu--BaMgAlO.sub.x.
[0024] It is believed that the present embodiments and their
advantages will be understood from the foregoing description, and
it will be apparent that various changes may be made thereto
without departing from the spirit and scope of the invention or
sacrificing all of its material advantages, the examples
hereinbefore described merely being preferred or exemplary
embodiments of the invention.
* * * * *