U.S. patent application number 09/233152 was filed with the patent office on 2002-03-14 for metal mold for producing a synthetic resin molded product in a compression-molding method.
Invention is credited to KOBAYASHI, YOSHITAKA, MATSUMOTO, MASAHITO, USUI, NOBUHIRO.
Application Number | 20020031568 09/233152 |
Document ID | / |
Family ID | 11664475 |
Filed Date | 2002-03-14 |
United States Patent
Application |
20020031568 |
Kind Code |
A1 |
MATSUMOTO, MASAHITO ; et
al. |
March 14, 2002 |
METAL MOLD FOR PRODUCING A SYNTHETIC RESIN MOLDED PRODUCT IN A
COMPRESSION-MOLDING METHOD
Abstract
The present invention relates to a metal mold for producing a
synthetic resin molded product in a compression-molding method. For
example, the present invention provides the followings: A metal
mold for producing a synthetic resin molded product in a
compression-molding method, which is constituted by a pair of male
and female molds which are allowed to mutually slide over the
entire contact face, with the outer circumferential face of the
male mold and the inner circumferential face of the female mold
serving as sliding portions at the time of mold-clamping,
characterized in that either the male mold or the female mold or
both of the molds is constituted by a mold main body and a sliding
member that constitutes a portion of the metal mold over the entire
sliding portions or on a portion thereof, and in that the sliding
member is freely removably attached to the mold main body. In
accordance with the metal mold of the present invention, in the
case when a synthetic resin molded product without a covering
material on its surface and a covering-material affixed synthetic
resin laminated product with a covering material on its surface
have the same design, a basic mold is commonly used by replacing
only the sliding member, without the need for using discrete
molding devices corresponding to the respective producing
processes; thus, the respective synthetic resin molded products can
be obtained in the same manner as the method for using the
respectively discrete molds.
Inventors: |
MATSUMOTO, MASAHITO; (OSAKA,
JP) ; USUI, NOBUHIRO; (OSAKA, JP) ; KOBAYASHI,
YOSHITAKA; (OSAKA, JP) |
Correspondence
Address: |
FITCH EVEN TABIN AND FLANNERY
120 SOUTH LA SALLE STREET
SUITE 1600
CHICAGO
IL
606033406
|
Family ID: |
11664475 |
Appl. No.: |
09/233152 |
Filed: |
January 19, 1999 |
Current U.S.
Class: |
425/193 |
Current CPC
Class: |
B29C 43/36 20130101 |
Class at
Publication: |
425/193 |
International
Class: |
B29C 043/36 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 19, 1998 |
JP |
10/007385 |
Claims
1. A metal mold for producing a synthetic resin molded product in a
compression-molding method, which is constituted by a pair of male
and female molds which are allowed to mutually slide over the
entire contact face, with the outer circumferential face of the
male mold and the inner circumferential face of the female mold
serving as sliding portions at the time of mold-clamping,
characterized in that either the male mold or the female mold or
both of the molds is constituted by a mold main body and a sliding
member that constitutes a portion of the metal mold over the entire
sliding portions or on a portion thereof, and in that the sliding
member is freely removably attached to the mold main body.
2. The metal mold according to claim 1, wherein the sliding
clearance of the male and female molds at the time of mold-clamping
is changed by a replacement of two or more of said sliding members
having different sliding clearances between the outer
circumferential face of the male mold or the inner circumferential
face of the female mold.
3. The metal mold according to claim 1 or 2, wherein the synthetic
resin is thermoplastic resin.
4. A molding device which is characterized by comprising the metal
mold as defined in claim 1, 2 or 3.
5. A method for producing a synthetic resin molded product, which
comprises the step of clamping the metal mold as defined in claim
1, 2 or 3.
6. Use of the metal mold as defined in claim 1, 2 or 3 for
producing a synthetic resin molded product.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a metal mold for producing
a synthetic resin molded product in a compression-molding
method.
[0003] 2. Description of the Prior Art
[0004] Thermoplastic resin molded products have been used in a wide
range including interior parts for cars (for example, door trims
and instrument panels), interior and exterior parts for home-use
electric appliances, etc., and the injection-molding method and the
compression-molding method are known as producing methods for such
thermoplastic resin molded products.
[0005] Moreover, these molded products are formed as thermoplastic
resin molded products without a covering material on their surface
or covering-material affixed thermoplastic resin laminated products
with a covering material on their surface depending on their
purposes and applications.
[0006] Conventionally, with respect to a molding method for the
thermoplastic resin molded product without a covering material on
its surface, the compression-molding method is widely used, in
which melted thermoplastic resin is supplied into the cavity of a
metal mold consisting of male and female molds and molding is
carried out by clamping the male and female molds. With respect to
the compression-molding method for the covering-material affixed
thermoplastic resin laminated product with a covering material on
its surface, a method which preliminarily provides a covering
material between the male and female molds before the melted
thermoplastic resin supplying process in the above-mentioned
molding method is widely used. (Japanese Laid-Open Patent
Publication No. 235613/1989 (Tokukai-hei 1-235613).
[0007] With respect to metal molds used for the above-mentioned
methods, in the case of the thermoplastic resin molded product
without a covering material on its surface, it is proposed that the
gap of the sliding portion of the male and female molds at the time
of mold-clamping be set in the range of 0.02 mm to 0.1 mm [see
Japanese Laid-Open Patent Publication No. 34819/1991 (Tokukai-hei
3-34819)], and in the case of the covering-material affixed
thermoplastic resin laminated product with a covering material on
its surface, it is also proposed that the above-mentioned gap be
set in the range of 0.25 to 3 times the restorable thickness of the
covering material [see Japanese Laid-Open Patent Publication No.
34830/1991 (Tokukai-hei 3-34830)].
[0008] Here, the restorable thickness of the covering material
refers to a thickness of a covering material upon application of a
maximum compression, which is defined as follows: after a pressure
has been applied onto only a covering material, the covering
material is allowed to restore its original thickness before the
application of the pressure; thus, this value differs depending on
the kinds, thickness, etc. of the covering material.
[0009] However, the problem with these methods is that since the
gap of the sliding portion of the male and female molds is
different between metal molds for producing the thermoplastic resin
molded product without a covering material and metal molds for
producing the covering-material affixed thermoplastic resin molded
product with a covering material, discrete metal molds have to be
used for the respective product modes even when those thermoplastic
resin molded products based upon the same design are produced.
BRIEF SUMMARY OF THE INVENTION
[0010] Under such circumstances, the inventors of the present
invention have made efforts to develop a metal mold which
eliminates the necessity of using respectively discrete molding
devices corresponding to the respective manufacturing processes in
the case when a synthetic resin molded product without a covering
material on its surface and a covering-material affixed synthetic
resin laminated product with a covering material on its surface
have the same design, and which makes it possible to easily produce
the two types of products using basically the same metal mold;
thus, the present invention has been devised.
[0011] In other words, the present invention provides
[0012] (1) a metal mold for producing a synthetic resin molded
product in a compression molding method, which is constituted by a
pair of male and female molds that are allowed to mutually slide
over the entire contact face, with the outer circumferential face
of the male mold and the inner circumferential face of the female
mold serving as sliding portions at the time of mold-clamping,
characterized in that either the male mold or the female mold or
both of the molds is constituted by a mold main body and a sliding
member that constitutes a portion of the mold over the entire
sliding portions or on a portion thereof, and in that the sliding
member is freely removably attached to the mold main body,
[0013] (2) the metal mold according to item no. 1, wherein the
sliding clearance of the male and female molds at the time of
mold-clamping is changed by a replacement of two or more of said
sliding members having different sliding clearances between the
outer circumferential face of the male mold or the inner
circumferential face of the female mold,
[0014] (3) the metal mold according to item no. 1 or 2, wherein the
synthetic resin is thermoplastic resin,
[0015] (4) a molding device which is characterized by comprising
the metal mold as defined in item 1, 2 or 3,
[0016] (5) a method for producing a synthetic resin molded product,
which comprises the step of clamping the metal mold as defined in
item 1, 2 or 3,
[0017] (6) use of the metal mold as defined in item 1, 2 or 3 for
producing a synthetic resin molded product.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] [FIG. 1]
[0019] FIG. 1 is a schematic cross-sectional view of a conventional
mold.
[0020] [FIG. 2]
[0021] FIG. 2 is a partial cross-sectional view of a metal mold of
the present invention.
[0022] [FIG. 3]
[0023] FIG. 3 is a partial cross-sectional view of the metal mold
shown in FIG. 2 of the present invention, in which the sliding
clearance has been changed.
[0024] [FIG. 4]
[0025] In the metal mold shown in FIG. 2 of the present invention,
FIG. 4 are schematic cross-sectional views showing the metal mold
(upper row) with a sliding member being removed therefrom and the
sliding member (lower row) that has been removed.
[0026] [FIG. 5]
[0027] FIG. 5 shows three examples of the layout of the sliding
member as plan views seen from the cavity surface of the metal
mold.
DESCRIPTION OF REFERENCE NUMERALS
[0028] 1: male mold
[0029] 1': mold main body
[0030] 2: female mold
[0031] 3: sliding member
[0032] 4a, 4b: sliding face
[0033] 5: bolt
[0034] 5a: bolt-inserting hole
[0035] 5b: bolt hole
[0036] A: sliding portion
[0037] W1, W2: sliding clearance
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0038] Referring Figures, the following description will discuss
embodiments of the present invention.
[0039] This embodiment is one example of the present invention, and
the present invention is, of course, not intended to be limited
thereby.
[0040] FIG. 1 is a schematic cross-sectional view that shows a
commonly-used metal mold consisting of a pair of female (1) and
male (2) molds; and portion A indicates a sliding portion that is
allowed to slide upon clamping the two molds.
[0041] FIG. 2 is a partial cross-sectional view of a metal mold of
the present invention that corresponds to the sliding portion of
the metal mold shown in FIG. 1; and it is constituted by a male
mold (1), a mold main body (1') and a sliding member (3). The
sliding portion (3), which is designed to form one portion of the
metal mold over the entire contact face of the sliding portion of
the male mold or on a portion thereof, is removably attached to the
mold main body, and as illustrated in the Figure, the sliding
member (3) and the mold main body (1') in their combined state form
the same shape as the male mold shown in FIG. 1, and have functions
as the male mold (1).
[0042] The upper row in FIG. 4 shows a state in which the sliding
member (3) has been removed from the combined state with the mold
main body (1') in FIG. 2, and the lower row in FIG. 4 shows the
sliding member (3) that has been removed.
[0043] In FIG. 2, the sliding face (4a) of the sliding member (3)
is designed so that, when combined with the mold main body (1'),
the sliding member is made identical to the outer circumferential
face of the mold main body (1'), and in this case, the distance
(sliding clearance) between the sliding face (4a) of the sliding
member (3) and the sliding face (inner circumferential face)(4b) of
the female mold (2) is set at W1.
[0044] FIG. 3 shows the same structure as the sliding member shown
in FIG. 2 except that, when the sliding member (3) is combined with
the same mold main body (1') as shown in FIG. 2, the sliding face
(4a) of the sliding member is maintained inside the outer
circumferential face of the mold main body (1'), and at this time,
the distance (sliding clearance) between the sliding face (4a) of
the sliding member (3) and the sliding face (inner circumferential
face) (4b) of the female mold (2) is set at W2.
[0045] Therefore, a plurality of sliding members in which W2 is
varied based upon the sliding clearance W1 are prepared, and these
sliding members are appropriately replaced so as to be combined
with the mold main body; thus, without entirely replacing a male
mold or a female mold or both of the molds, as a whole, the gap
(sliding clearance) of the sliding portions between the male and
female molds can be desirably adjusted. Therefore, the respective
constructions are applied in the same manner as a plurality of
discrete molds.
[0046] The thickness (distance from the sliding face (4a)) and the
height (distance from the mold cavity face) of the sliding member
(3) are appropriately determined in the light of the strength
defined as an independent member and the size of the metal mold
itself, and its shape is not specifically limited, as long as it is
a shape that is allowed to function as a male or female mold as a
whole.
[0047] With respect to the material of the sliding member (3),
steel, which is generally used as a material for metal molds, is
generally adopted; however the material is not specifically
limited, and for example, zinc alloy, aluminum alloy, copper alloy,
etc. may be used, and the same material as the mold main body or
the material different therefrom may be used.
[0048] In the case of a narrow sliding clearance, when the metal
mold face slides against the sliding member, the sliding face
corresponding to the product designed surface might be worn out,
with the result that the product appearance is adversely affected;
therefore, for the metal mold or the sliding member on the product
designed surface, it is preferable to select a material having a
hardness higher than that of the material used for the metal mold
or the sliding member on the non-product designed surface so as to
prevent the sliding face corresponding to the product designed
surface from being worn out upon sliding operations.
[0049] The sliding member (3) needs to be removably attached to the
mold main body (1') so as to allow for replacement, and it is
preferably designed to be firmly integrated into one unit when
combined with the mold main body, and also to be easily detached
upon replacement. With respect to such attaching and detaching
means, for example, a method for using screws, bolts (5), etc. as
shown in FIG. 2, and a method for using a precise snap-in system
between the sliding member (3) and the mold main body (1') are
listed; however, the means is not limited, and an appropriate
method is selected.
[0050] Upon producing synthetic resin molded resin product by using
such a metal mold, in the case of the synthetic resin molded
product without a covering material on its surface, the sliding
face (4a) of the sliding member is designed so that when the
sliding member (3) is combined with the mold main body (1'), it is
made identical to the outer circumferential surface of the mold
main body (1') as illustrated in FIG. 2, and a mold, in which the
sliding member whose sliding clearance at this time is W1 is
combined with the mold main body, is used; thus, the sliding
clearance W1 at this time is set as a gap that does not allow
melted synthetic resin supplied at the time of mold-clamping to
leak therefrom and that is suitable for molding without allowing
air to remain inside the metal mold. In general, the gap (sliding
clearance) is set in the range of 0.02 to 0.1 mm; however, in
practice, this is appropriately determined in accordance with
various conditions, such as kinds, viscosity, temperature, the
amount of supply of a synthetic resin to be used and the shape of
the metal mold.
[0051] Moreover, in the case of the covering-material affixed
synthetic resin laminated product with a covering material on its
surface, the sliding member that was previously used is removed
from the mold in which the sliding member was combined with the
mold main body, and a mold in which a sliding member having the
same construction as the previously-used sliding member except that
the sliding clearance is set at W2 is combined with the same mold
main body, is used as shown in FIG. 3; thus, the sliding clearance
W2 at this time is set at a gap that does not allow a melted
synthetic resin supplied at the time of mold-clamping to leak
therefrom, that allows the covering material to be squeezed into
the metal mold without being subjected to an excessive, unnecessary
resistance in the clearance section at the time of mold-clamping,
and that makes it possible to provide a laminated molded product
free from tearing in the covering material, wrinkles, whitening
phenomenon, etc. after molding. In general, the sliding clearance
is set in the range of 0.25 to 3 times the restorable thickness of
the covering material that is commonly used; however, in practice,
this is appropriately determined in accordance with various
conditions, such as kinds, viscosity, temperature, the amount of
supply of a synthetic resin to be used and the shape of the metal
mold.
[0052] In the metal mold of the present invention, for synthetic
resin molded products formed based on the same design with or
without a covering-material on their surface, a decision as to
whether the sliding member constitutes a portion of the metal mold
over the entire sliding portion or on a portion thereof, i.e. the
sliding member is placed over the entire outer circumferential
portion of the mold main body or on a portion thereof, is made
depending on the layout of the covering material; however, in
general, the sliding member is placed over the entire
circumferential portion of the mold main body when the covering
material is affixed over the entire surface (i.e. entire
lamination), and it is placed on a portion of the outer
circumferential portion of the mold main body corresponding to the
layout position of a covering material when the covering material
is partially affixed (i.e. partial lamination).
[0053] In both cases of the entire lamination or the partial
lamination of the covering material, the sliding member may, of
course, be partially placed in a dispersed manner so as to place
one or a plurality of them, without being placed over the entire
outer circumferential portion of the mold main body corresponding
to the layout position of the covering material, depending on
factors such as the shape of synthetic resin molded products, the
property of the covering material and the molding conditions.
[0054] Moreover, in the case when the desired sliding clearance
varies partially depending on the shape of products, the property
of the covering material, etc., a single sliding member, designed
so as to have optimal sliding clearances at the respective
portions, may be used, or sliding members having different
clearances may be appropriately combined.
[0055] FIG. 5 shows layouts of such sliding members as plan views
seen from the cavity surface of a metal mold; (a) is an example in
which the sliding member (3) is placed over the entire outer
circumferential portion of the mold main body upon lamination of
the covering material over the entire surface, (b) is an example in
which the sliding member (3) is placed on a portion of the outer
circumferential portion of the mold main body upon lamination of
the covering material over the entire surface, and (c) is an
example in which the sliding members (3) is placed on the outer
circumferential portion of the mold main body corresponding to the
covering-material position upon partial lamination of the covering
material.
[0056] In the above-mentioned explanation, the sliding member (3)
is placed on the male mold (1); however, the sliding member may be
placed on the female mold (2), and may, of course, be placed on
both of the male and female molds. Further, the positional
relationship of the male and female molds may be reversed, and the
installation of them is appropriately determined.
[0057] Furthermore, in the metal mold of the present invention, no
difference is made by the mold-clamping direction upon molding, and
the mold-clamping may be applied either in up and down directions
or in right and left directions.
[0058] In the case when synthetic resin molded products having the
same design with or without a covering material on their surface
are produced by using the above-mentioned metal molds, a
conventionally-known, general molding method, which is the same as
the method for using respectively discrete molds, may be applied,
as it is, except that the sliding member (3) is replaced so that
the sliding clearance W is equal to a desired gap between the male
and female molds, depending on the presence or absence of a
covering material, the kind of the covering material, the kind of
the synthetic resin to be used, etc.; therefore, no specific
molding conditions are required for the application of the metal
mold of the present invention.
[0059] For example, when a molding process is carried out by using
the injection compression molding method, a sliding member, which
is designed to have an optimal sliding clearance depending on
factors, such as the presence or absence of a covering material and
the kind of synthetic resin to be used, is attached to the mold
main body, and melted synthetic resin is provided between male and
female molds that are in an open state. Alternatively, upon the
lamination of the covering material, after having preliminarily
supplied the covering material, melted synthetic resin is supplied,
and after having been mold-clamped, this is cooled off and
solidified, and then by opening the metal mold, an objective
synthetic resin molded product is obtained in the same manner as
the conventional method.
[0060] Similarly, with respect to synthetic resins and covering
materials used as materials, no specific limitation is applied; for
synthetic resins, the following materials, which are generally used
for compression-molding method, injection-molding method, and
extrusion-molding method, are listed: common thermoplastic resins
such as polypropylene, polyethylene,
acrylonitrile-styrene-butadiene block copolymer, polystyrene,
polyamides such as nylon, polyvinylchloride, polycarbonate, acrylic
resins and styrene-butadiene block copolymer, thermoplastic
elastomers such as EPM and EPDM, mixtures of these, polymer alloys
using these, etc. may be used. These may have a non-foaming
property or a foaming property.
[0061] These synthetic resins may contain, if necessary, fillers
such as talc, glass fiber, various inorganic or organic fillers,
which are generally used, and may also contain various additive
agents such as antioxidants, antiultraviolet agent, various
pigments, lubricating materials, static-eliminating agents and
stabilizers, which are generally used.
[0062] Moreover, with respect to the covering material, various
conventionally-known covering materials including various woven
cloth, knitted cloth, non-woven cloth, and sheets and films of
synthetic resins such as thermoplastic resin and thermoplastic
elastomer, as well as paper, metal foil, net-shaped objects or
foamed sheets of synthetic resins such as thermoplastic resin and
thermoplastic elastomer, may be used, and these covering materials
may be decorated by protruding and recessed patterns such as grain,
printing, coloring, etc. Moreover, these covering materials are
used not only as independent parts, but also as composite covering
materials having laminated layers of two or more kinds such as
thermoplastic elastomer sheets of polyvinyl chloride sheets and
EPDMs having lining materials of foamed sheets such as
polypropylene foamed sheets.
[0063] Upon application of the covering material, a preheating
process may be carried out so as to improve the bonding property
between the covering material and the synthetic resin such as
thermoplastic resin, or a preparatory forming process may be
applied depending on shapes of the synthetic resin molded
product.
[0064] Furthermore, a supporting frame for supporting the edge of
the covering material may be placed along the circumferential
portion of the metal mold, if necessary.
* * * * *