Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting – Controlling heat transfer with molding material
Reexamination Certificate
2002-01-15
2004-06-01
Heitbrink, Jill L. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
Controlling heat transfer with molding material
C264S328160, C249S111000, C425S407000, C425S470000
Reexamination Certificate
active
06743384
ABSTRACT:
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION
The present invention is generally directed to molds and molding processes, and more particularly to a method and an apparatus for molding processes that utilize an anisotropic diffuser member for uniformly distributing heat within a mold die.
BACKGROUND OF THE INVENTION
The processing of molded materials is a precise operation requiring the precisely timed application of pressure and the application of precise and uniform temperature. Any deviation from the desired parameters often leads to cracks and/or poor resin flow in the resulting product.
The background art includes several examples of related control schemes for regulating mold process temperatures. For example, U.S. Pat. No. 3,933,335 to Maruyama et al. describes a casting mold for casting metals that includes a paper-like sheet of carbon fibers admixed with organic fibers or pulp that is used as a liner between the molten metals within the mold and the mold's interior surface. The carbon fiber sheets include at least 35 percent by weight of carbon fibers in order to prevent undesirable stresses and seizure as a result of contact between the molten metal and the interior surface of the mold.
U.S. Pat. No. 4,388,068 to Suh et al., the entirety of which is herein incorporated by reference, describes an injection molding device and method that includes the use of a variable conductance heat pipe for controlling the rate of cooling of portions of a mold cavity surface separately and independently from other portions of the mold cavity surface. This molding device and method inherently relies upon individualized, active temperature regulation and temperature approximation of numerous sub portions at various locations of the mold.
U.S. Pat. No. 5,154,221 to Vatant et al. describes a device for fixing and cooling a graphite block of a graphite wall of a mold. A mold cavity is formed by a plurality of vertically oriented graphite blocks that make up the mold cavity walls. The individual graphite blocks contain vertical bores arranged in parallel to the surface of the mold cavity walls. Each of the bores permits sprayed jet(s) of cooling fluid into the interior of the blocks to effect cooling of the mold cavities. However, the device of Vatant et al. requires a system for collection and delivery of cooling fluid and/or additional machining of parts to create the vertical bores of each graphite block and cooling system.
U.S. Pat. Nos. 5,609,922; 5,746,966; and 5,783,259, all to McDonald, describe methods and molds for molding processes that incorporate thermal coatings applied to an interior surface of a mold cavity via the use of a thermal spray. The coatings may include ceramics, metal matrix composites, ceramic matrix composites, resins and various combinations thereof. The thermal coating is selected to impart a desired porosity into the interior surface of the mold cavity that will aid in rapid cooling and will add to the structural strength of the mold itself. However, the methods and devices of McDonald rely upon precision manufacturing techniques that necessitate controlled thermal spraying of coatings onto mold cavity components of various sizes and shapes.
U.S. Pat. No. 5,811,135 to Kimura, the entirety of which is herein incorporated by reference, describes a molding apparatus having a conventional molding box structure with a thermally expanding member.
FIG. 1
is a side view of a molding apparatus according to the background art.
FIG. 2
is a front elevation view of a mold member for the molding apparatus of FIG.
1
.
FIG. 3
is an exploded perspective view of the mold member for the molding apparatus of FIG.
1
.
FIG. 4
is a sectional view of a molten material filling mechanism for a molding apparatus according to the background art.
As seen in FIG.
1
through
FIG. 4
, a molding box structure
10
includes horizontally arranged support elements
11
, threaded struts
12
, and a plurality of nuts
13
. A mold member
20
(shown in two parts, e.g., an upper half
21
and a lower half
22
), a pressurizing plate
30
, a thermally expanding member
40
and an auxiliary pressurizing mechanism
50
are vertically arranged between the lower two support elements
11
in this order from top to bottom. The thermally expanding member
40
includes a temperature adjusting mechanism
60
.
The temperature adjusting mechanism
60
is used to control the pressure that the thermally expanding member
40
imparts to the mold member
20
to sealingly engage the upper and lower halves
21
,
22
of the mold member. The temperature adjusting mechanism
60
also includes a cylindrical heater (not shown) for heating and expanding the thermal expansion member
40
. A cooling oil circuit (not shown) is used to contract and cool the thermally expanding member
40
.
During a conventional molding process, the mold member
20
is accommodated between the pressurizing plate
30
and one of the support elements
11
a
2
. The upper and lower molds
21
and
22
have concavities formed in faces opposed to each other, in predetermined configurations, respectively. Each of the molds
21
and
22
further has a plurality of positioning pins
23
for preventing lateral misalignment. The upper mold
21
has a material filling hole
21
a
formed therethrough to correspond to the central cylinder hole
71
formed through the support plate
11
a
, as shown in FIG.
4
.
A thrusting piston
72
is insertable into the cylinder hole
71
and is connected to a piston
73
a
of an oil-hydraulic cylinder mounted on and extending through a central portion of the uppermost support plate
11
b
. Movement of the piston
73
a
vertically moves the thrusting piston
72
so that molten material accommodated in the cylindrical hole
71
can fill the interior of the mold member
20
through the material filling hole
21
a
of the upper mold
21
. Depending on the type of molding process undertaken, the finished molded product is demolded after the required cooling process or molding process is completed.
However, the aforementioned arrangements of the background art lack a simple method for ensuring the elimination of temperature gradients, e.g., hot spots or other temperature variations along variation portions of the mold cavity. These temperature gradients will likely result in surface cracking, sinks, warping and other forms of distortion or surface irregularity. When the mold cavity is heated in an attempt to ensure adequate mold cavity, e.g., the temperature of the melt, the transfer of heat to the mold cavity should be in a controlled, uniform manner that ensures that temperature control does not result in undesirable heating of the melt that may lead to increased mold cooling times and overall process cycle times.
SUMMARY OF THE PRESENT INVENTION
The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.
The present invention, in part, is a recognition that it will be advantageous to uniformly distribute heat within a mold die or molding cavity during a molding process.
The present invention, in part, is a recognition that the unique properties of fiber reinforced composites can be utilized to produce precision temperature control and heat transfer if manipulated to have a predetermined geometry.
The present invention, in part, provides a mold assembly for a molding process comprising a mold member and an anisotropic diffuser member, the diffuser member comprising a fibrous composite having a plurality of fibers each having a respective length, the fibers being arranged in a lay-up with the length of each fiber arranged in a substantially uniform direction within the diffuser member, wherein the diffuser member is arranged in a position permitting a rapid transfer of heat along the length of each fiber to the mold member.
The present invention, also in part, provides an anisotropic diffuser plate for a mold assembly, the diffuser plate comprising a fibrous composite having a plurality of fibers each
Lukas Ken S.
Yen Chenglung E.
Heitbrink Jill L.
Honeywell International , Inc.
Palguta Larry J.
LandOfFree
Anisotropic heat diffuser plate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Anisotropic heat diffuser plate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Anisotropic heat diffuser plate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3357080