CA1274062A - Foam slush molding apparatus - Google Patents
Foam slush molding apparatusInfo
- Publication number
- CA1274062A CA1274062A CA000534232A CA534232A CA1274062A CA 1274062 A CA1274062 A CA 1274062A CA 000534232 A CA000534232 A CA 000534232A CA 534232 A CA534232 A CA 534232A CA 1274062 A CA1274062 A CA 1274062A
- Authority
- CA
- Canada
- Prior art keywords
- hot air
- jacket
- air chamber
- slush molding
- molding apparatus
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/02—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means
- B29C33/04—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means using liquids, gas or steam
- B29C33/046—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means using liquids, gas or steam using gas
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/34—Component parts, details or accessories; Auxiliary operations
- B29C41/46—Heating or cooling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
- B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
- B29C44/04—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles consisting of at least two parts of chemically or physically different materials, e.g. having different densities
- B29C44/0461—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles consisting of at least two parts of chemically or physically different materials, e.g. having different densities by having different chemical compositions in different places, e.g. having different concentrations of foaming agent, feeding one composition after the other
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/02—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means
- B29C33/04—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means using liquids, gas or steam
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C37/00—Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00
- B29C37/0025—Applying surface layers, e.g. coatings, decorative layers, printed layers, to articles during shaping, e.g. in-mould printing
- B29C37/0028—In-mould coating, e.g. by introducing the coating material into the mould after forming the article
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
- B29C41/18—Slush casting, i.e. pouring moulding material into a hollow mould with excess material being poured off
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
- B29K2027/06—PVC, i.e. polyvinylchloride
Abstract
ABSTRACT
The foam slush molding apparatus of this invention comprises a mold, a hot air jacket, and a heat retaining hood.
The hot air jacket and the heat retaining hood are provided along and a certain distance apart from the molding surface on which a resin is heated and fused. The molding surface and the jacket form a first hot air chamber for heating, and the jacket and the heat retaining hood form a second hot air chamber for heat retention. Switching means are provided for diverting hot air alternately and controllably to said first hot air duct and to said second hot air duct. The apparatus permits uniform heating and foaming with an efficient molding cycle.
The foam slush molding apparatus of this invention comprises a mold, a hot air jacket, and a heat retaining hood.
The hot air jacket and the heat retaining hood are provided along and a certain distance apart from the molding surface on which a resin is heated and fused. The molding surface and the jacket form a first hot air chamber for heating, and the jacket and the heat retaining hood form a second hot air chamber for heat retention. Switching means are provided for diverting hot air alternately and controllably to said first hot air duct and to said second hot air duct. The apparatus permits uniform heating and foaming with an efficient molding cycle.
Description
~ 7~V~
FOAM SLUSH MOLDING APPARATUS
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a foam slush molding appa-ratus which performs molding and foaming simultaneously.
FOAM SLUSH MOLDING APPARATUS
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a foam slush molding appa-ratus which performs molding and foaming simultaneously.
2. Descrip_ion of the Prior Art:
Slush molding involves the basic steps of filling a pre-heated mold with a plastisol, which is a highly viscous liquid composed of fine particles of plastics and plasticizer, causing the plastisol to stick to the inside of the mold, inverting the mold to pour out the excess plastisol, exposing the mold to heat for gelation of the sol sticking to the inside of the mold, and cooling the mold. This type of molding is conventionally called sol slush molding.
There is another type of slush molding, which is called pow-der slush molding. This molding process employs powdered resin.
The "foam slush molding" of the present invention can employ a sol or powdered resin containing a blowing agent and performs gelatio~ and foaming simultaneously. This molding process may be used for making automotive instrument panels which have a thin skin of, for example, plasticized polyvinyl chloride (PVC).
The heating and foaming of a resin containing a blowing agent are usually accomplished by the use of hot air or infrared radiatio For example, foamed PVC sheet is produced b~ passing ~ ................... .... .
~ ~ ., . '.':'~'~P~ V~), ' b ~74~
an unrolled stock sheet contin~ously through a hot-air oven at about 200C. This foaming methocl is adequate fvr sheet-like ob-__ jects which are uniformly heated. ~owever, it is inadequate forobjects of complex shape which are not uniformly heated. In the latter case, excessive foaming takes place on those parts suffi-ciently exposed to heat ` and insufficient foaming takes place on other parts which are not sufficiently exposed to heat. As a result, the ~oamed skin is unsatisfactory. The disadvantage of heating by infrared radiation is that undercuts and other parts are not ¦exposed to radiation.
The present invention was completed in view of the above-mentioned circumstances. Accordingly, it is an object of the present invention to provide a molding apparatus capable of uniformly foaming the plastic or resin constituting a skin of complex shape.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by prac-tice of the invention. The objects and advantages of the inven-tion may be realize~d and attained by means o~ the instrumen-talities and combinations particularly pointed out in the appended claims.
SUMMARY OF THE INVENT r ON
To achieve the objects and in accordance with the purpose of the invention as embodied and broadly described herein, the foam slush molding apparatus of this invention comprises a mold and a hot air jacket provided along and a certain or predetermined dis-tance apart from the molding surface on which the resin is heated and fused. The mold and jacket form a first hot air chamber that supplies heat for foaming. The first hot air chamber is provided with a hot air inlet and a hot air outlet.
The molding apparatus is constructed such that hot air is forced into the first hot air chamber through the hot air inlet to heat the resin powder in contact with the molding surface, and it is discharged through the hot air outlet. Molding with this apparatus is carried out as follows. The mold is preheated, the preheated mold is filled with plastisol, and the excess plastisol is removed, for example, dumped out. The hot air jacket (made of an insulating material) is positioned with the mold, for example, placed on the mold, and hot air is forced into the first hot air chamber so that gelation and foaming take place uniformly all ¦over the molding surface. Therefore, the molding apparatus of this invention permits uniform foaming no matter ho~ complex the shape of the molded item might be. In addition, it permits one to easily control the expansion ratio, (i.e., the ratio of foaming material thickness hefore and after foaming).
The molding apparatus of the present inventian obviates the conventional heating oven, and it produces pronounced energy sav ings because it re~uires only a minimum amount of hot air for heating.
~ ~ 7~3~
If the gap be~ween the 61ush mold and the hot air ~acke~ is less than about S mm, the hot air d~les not pass freely because of high resistance. This induces local suppression of foaming. By gradually ~arying the gap, it is possible to produce a foamed product with a soft texture, since local suppression of foaming occurs in the narrow gap regions.
- For the effective heating of resin with the apparatus of this invention, the hot air jacket can be provided with a heat insulating or heating meens. An example of the heat insulating means is a metal hood to cover the hot air jacket, and ~n example of the heatinq means is a heater built into the hot air jacket.
~here a metal hood is used for heat insulation, it is necessary to provide a motor and support to open and close the hood and a space to permit movement of the hood.
Where a built-in heater is used, the hot air is not used to keep the hot a~r jacket heated after the heating cycle. In other words, in the cycle for the gelation of the resin, hot air is supplied to the first hot air chamber, and in the followinq cycle with no heating, the hot air jacket cools. However, it is desir-able to keep the hot air jacket hot after the heating cycle to repeat the molding and foaming efficiently in a short cycle.
This is accomplished only by the buîlt-in heater.
The above-mentioned shortcoming is eliminated by the slush mo~ding apparatu5 of the present invention constructed as fol-lows. The hot air jacket is provided along and a certain dis-tance apart from the moldin~ surface so that. the first hot air cha~ber (for hea~ing and foaming) is formed between the mold and the jacket. The heat insulating hood is pro~ided outsi~e the hot air jacket so that a second hot air chamb2r ~for heat retention) is formed between them. The first hot air chamber is connected to a first duct for providing hot air for heating purposes through the hot air inlet. The second hot air chamber is con-nected to a second duct for providing hot air for heat retention.
When the resin is to be heated, hot air is introduced into the first hot air chamber through the first duct. In the non-heating cycle, hot air for heat retention is introduced into the second hot air chamber through the second duct.
The apparatus of this invention has the heat insulating hood outside the hot air jacket, so that hot air is introduced into the second chamber formed between them in the cycle when the resin is not heated. Therefore, the hot air jacket does not cool but remains hot even after the molding and foaming of the resin.
This contributes to the shortening of the molding and foaming cycles.
In addition, the hot air jacket is kept hot by the hot air.
Thus, it is unnecessary to add an apparatus for heat retention and hence to provide the space for it.
The accompanying drawings which are incorporated in and con-stitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to ex-plain the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a sectional view of one embodiment of the present invention as describec in Exa LZ7~0~
Fig. 2 is a sectional view takell along the line A~ in . FigO 1. , . _ ~ ig. 3 is an enlarged sectional vie~ of t~e part indicate~
by B in Fig. 1.
Fig. 4 is a sectional view of a foamed skin obtaaned by foam slush molding using the apparatus of the present in~ention as described in Example 1.
Fig. S is a sectional view of another embodiment of the apparatus of the present invention as descrabed in Example 2.
Fi~. 6 is a sectional view of the foamed skin obtained by foam slush molding using the apparatus of the present invention ~s described in Example 2.
Fig. 7 is a schematic drawing of still another embodiment of . t:he apparatus of the present invention as described in Example 4.
Fig~ 8 is a schematic plan view of the apparatus shown in Fiq. 7.
Fig. 9 is a sec~ional view taken along the line A - A. in Fig. 7.
Fig. 10 is a sectional view taken along the line B-~ in ~iq.
7.
~ ig. 11 is a sectional view o~ the foamed skin obtained by a ~on~entional foam slush ~olding apparatus.
As s~ated above, the prior art heating and foaming of a res~n contai~ing a blowing agent by the use o hot al~ or infrared radiation tends to be inadequate for objects o~
complex shapo ~hich are n~t uniformly heated. Re~erring to Eigure ~1 of tha d~a~ingst ~or example, e~cessive foaming takes place on ~hose parts sufficie~tlr exposed to ~eat, these par~s bein~ periphQry 1 and vertical s~r~ace 2. On the other hand~
it c~a~ ba seen l:hat insuicient foa~ing ~as oc~ red on o~her parts ~ c~ not suf~lc~en~ly exposed to heat.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to preferred embodi-ments of the invention, examples of which are illustrated in the accompanying drawings.
- 6a -,/j 1~4U~ ~
Example 1 Fig. 1 shows a sectional view of one embodiment of the appa-ratus of the present invention. It shows a mold 4 for slush molding, a removable hot air jacket 5 made of an insulating mate-rial, and a gap 6 formed between the mold 4 and the hot air jack-et 5. The gap is, for example, 15 mm, and uniform throughout.
Fig. 2 shows a sectional view taken along the line A-A in Fig. 1. The external edge 7 of the hot air jacket 5 functions as the lid of the gap 6 that keeps the hot air in the jacket.
A hot air generator 8 is also shown in Fig. 1. Hot air is introduced into the gap 6 through the hose 9 and the hot air inlet 10. The hot air flows through the gap 6 at a uniform flow rate and exits at the hot air outlet 11.
The operation of the apparatus includes the following steps.
At first, the skin 12 composed of a solid PVC layer (for example, 0.3 to 0.5 mm thick) and an expandable PVC layer (for example, 0.5 to 0.8 mm thick) containing a blowing agent is formed by or-dinary slush molding. After the recovery of excess plastisol or powder, the hot air jacket 5 is positioned and hot air is intro-duced into the gap 6 so that heat is applied to the expandable PVC layer of the skin. As a result of heating, a uniformly foamed skin 3 having the foam layer, for example, 2.5 to 3.0 mm .
thick is obtained, as shown in Fig. 3 which is an enlarged sec-tional view of the part indicated by B in Fig. 1. The solid PVC
layer 13 and the expanded layer 1~ are shown in Figs. 3 and ~.
~ ~ 7 Example 2 In cases where the molded item has some parts which do not need complete expansion, the gap 6 for hot air may be partly nar-rowed, for example, to less than 5 mm, as shown in Fig. 5. The reduction of hot air by the narrowed part suppresses the foaming, as shown in Fig. 6. If the hot air jacket 5 is properly designed so that the gap gradually varies, it is possible to produce a foamed product with a soft texture.
Example 3 If hot air is introduced into the gap 6 when the hot air jacket 5 is at normal temperature, the heat of the hot air is absorbed by the jacket 5. This may be prevented by positioning the jacket 5 and passing hot air through the gap prior to the slush molding. Another way to perform efficient heating is to keep the jacket hot at all times by means of a heater built into the jacket.
Example 4 The apparatus of this example is shown in Fig. 7. The skin 31 of the resin to be heated is formed on the molding surface 30a of the mold 30. The skin is composed of a solid PVC layer (for example, 0.3 to 0.5 mm thick) fdrmed by conventional slush mold-ing and an expandable PVC layer (for example, 0.5 to 0.8 mm thick) containing a blowing agent.
The hot air jacket 32 is provided along and a certain dis-tance (for example, 5 to 20 mm) apart from the molding surface 30a of the mold 30. The heat retaining hood 33 is provided along ~ 7~a~6~ 1 and a certain distance (for example, 10 to 50 mm) apart from the hot air jacket 32. Thus, a first hot air chamber 34 (for heat-ing) is formed between the molding surface 30a of the mold 30 and the hot air jacket 32, and a second hot air chamber 35 (for heat retention) is formed between the hot air jacket 32 and the heat retaining hood 33.
The hot air jacket 32 is provided with an inlet 32a for hot air used for heating, and the heat retaining hood 33 is provided with an inlet 33a for hot air used for heat retention. Hot air introduced through the inlet 32a for heating purposes impinges upon the molding surface 30a of the mold 30 opposite to the inlet 32a. The hot air impinging upon the molding surface 30a should have a uniform pressure. For this reason, that part (including the vicinity thereof) of the mold 30 which is adjacent, e.g., op-posite to the inlet 32a for the hot air for heating purposes is recessed in the flow direction of the hot air.
The inlet 32a for the hot air for heating purposes is con-nected to a first duct 36 for said hot air for heating purposes, and the inlet 33a for the hot air ~or heat retention is connected to a second duct 37 for said heat retaining hot air. The two ducts 36 and 37 are combined into a main duct 38. At the point where the two ducts 36 and 37 are combined or at the point where the main duct 38 is branched into the two ducts, there is provid-ed a diverter valve 39. Thus, the hot air supplied through the main duct 38 is directed to either the duct 36 or the duct 37, ~¦ ~depending n the position of the valve disk 39a of the diverter I ~ ~7~`~ 1 valve 39. The forward end of the duct 36 is coaxially inserted into the forward end of the duct 37, so that they form a double duct. The reference numeral 20 indicates the hot air generator connected to the main duct 38.
As shown in Figs. 7 and 8! a sealing material 21 is inter-posed between the periphery of the mold 30 and the periphery of the hot air jacket 32, and a sealing material 22 is interposed between the periphery of the hot air jacket 32 and the periphery of the heat retaining hood 33. These sealing materials improve the air tightness of the first hot air chamber 34 (for heating) and the second hot air chamber 35 (for heat retention). The sealing materials 21 and 22 are partially cut to form the outlets ¦
23 for hot air. The number and position of the outlets 23 are properly determined to control the flow direction of hot air in the hot air chambers 34 and 35.
Figs. 9 and 10 show the detailed structures of the hot air chamber 36 for heating and the hot air chamber 37 for heat reten- ¦
tion. In this example, the diverter valve 39 is a three-way valve which diverts the flow of hot air to either the duct 36 or the duct 37. Figs. 9 and 10 show an insulating material 24 pro-vided outside the heat retaining hood 33, a support 25 to support ¦
the mold 30, hot air jacket 32 and heat retaining hood 33, and valve 2~ to control the flow rate of hot air.
The apparatus described in Example 4 operates in the follow-ing manner. At first, the mold 30 is filled with plastisol or resin powder so that a fused resin layer is formed on the molding 7 ~
surface 30a. Excess plastisol or resin powder is then recovered.
The hot air jacket 32 and the heat retaining hood 33 are posi-tioned with the mold. The valve disk 39a of the diverter valve 39 shown in Fig. 7 is switched to the position shown so that the main duct 38 communicates with the hot air duct 36. Hot air is supplied to the first hot air chamber 34, whereby the resin 31 is heated. After the heating is completed, the valve disk 39a of the diverter valve 39 is switched to the position indicated by the dotted line, so that the main duct 38 communicates with the duct 37. Hot air is supplied to the second hot air chamber 35 so that the hot air jacket 33 is heated from outside and kept hot.
The hot air introduced into the first hot air chamber 34 for 1`
heating or the second hot air chamber 35 for heat retention is discharged from the outlet 23.
It will be apparent to those skilled in the art that various modifications and variations can be made in the foam slush mold-ing apparatus of the present invention without departing from the scope or spirit of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and th r equivalents.
Slush molding involves the basic steps of filling a pre-heated mold with a plastisol, which is a highly viscous liquid composed of fine particles of plastics and plasticizer, causing the plastisol to stick to the inside of the mold, inverting the mold to pour out the excess plastisol, exposing the mold to heat for gelation of the sol sticking to the inside of the mold, and cooling the mold. This type of molding is conventionally called sol slush molding.
There is another type of slush molding, which is called pow-der slush molding. This molding process employs powdered resin.
The "foam slush molding" of the present invention can employ a sol or powdered resin containing a blowing agent and performs gelatio~ and foaming simultaneously. This molding process may be used for making automotive instrument panels which have a thin skin of, for example, plasticized polyvinyl chloride (PVC).
The heating and foaming of a resin containing a blowing agent are usually accomplished by the use of hot air or infrared radiatio For example, foamed PVC sheet is produced b~ passing ~ ................... .... .
~ ~ ., . '.':'~'~P~ V~), ' b ~74~
an unrolled stock sheet contin~ously through a hot-air oven at about 200C. This foaming methocl is adequate fvr sheet-like ob-__ jects which are uniformly heated. ~owever, it is inadequate forobjects of complex shape which are not uniformly heated. In the latter case, excessive foaming takes place on those parts suffi-ciently exposed to heat ` and insufficient foaming takes place on other parts which are not sufficiently exposed to heat. As a result, the ~oamed skin is unsatisfactory. The disadvantage of heating by infrared radiation is that undercuts and other parts are not ¦exposed to radiation.
The present invention was completed in view of the above-mentioned circumstances. Accordingly, it is an object of the present invention to provide a molding apparatus capable of uniformly foaming the plastic or resin constituting a skin of complex shape.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by prac-tice of the invention. The objects and advantages of the inven-tion may be realize~d and attained by means o~ the instrumen-talities and combinations particularly pointed out in the appended claims.
SUMMARY OF THE INVENT r ON
To achieve the objects and in accordance with the purpose of the invention as embodied and broadly described herein, the foam slush molding apparatus of this invention comprises a mold and a hot air jacket provided along and a certain or predetermined dis-tance apart from the molding surface on which the resin is heated and fused. The mold and jacket form a first hot air chamber that supplies heat for foaming. The first hot air chamber is provided with a hot air inlet and a hot air outlet.
The molding apparatus is constructed such that hot air is forced into the first hot air chamber through the hot air inlet to heat the resin powder in contact with the molding surface, and it is discharged through the hot air outlet. Molding with this apparatus is carried out as follows. The mold is preheated, the preheated mold is filled with plastisol, and the excess plastisol is removed, for example, dumped out. The hot air jacket (made of an insulating material) is positioned with the mold, for example, placed on the mold, and hot air is forced into the first hot air chamber so that gelation and foaming take place uniformly all ¦over the molding surface. Therefore, the molding apparatus of this invention permits uniform foaming no matter ho~ complex the shape of the molded item might be. In addition, it permits one to easily control the expansion ratio, (i.e., the ratio of foaming material thickness hefore and after foaming).
The molding apparatus of the present inventian obviates the conventional heating oven, and it produces pronounced energy sav ings because it re~uires only a minimum amount of hot air for heating.
~ ~ 7~3~
If the gap be~ween the 61ush mold and the hot air ~acke~ is less than about S mm, the hot air d~les not pass freely because of high resistance. This induces local suppression of foaming. By gradually ~arying the gap, it is possible to produce a foamed product with a soft texture, since local suppression of foaming occurs in the narrow gap regions.
- For the effective heating of resin with the apparatus of this invention, the hot air jacket can be provided with a heat insulating or heating meens. An example of the heat insulating means is a metal hood to cover the hot air jacket, and ~n example of the heatinq means is a heater built into the hot air jacket.
~here a metal hood is used for heat insulation, it is necessary to provide a motor and support to open and close the hood and a space to permit movement of the hood.
Where a built-in heater is used, the hot air is not used to keep the hot a~r jacket heated after the heating cycle. In other words, in the cycle for the gelation of the resin, hot air is supplied to the first hot air chamber, and in the followinq cycle with no heating, the hot air jacket cools. However, it is desir-able to keep the hot air jacket hot after the heating cycle to repeat the molding and foaming efficiently in a short cycle.
This is accomplished only by the buîlt-in heater.
The above-mentioned shortcoming is eliminated by the slush mo~ding apparatu5 of the present invention constructed as fol-lows. The hot air jacket is provided along and a certain dis-tance apart from the moldin~ surface so that. the first hot air cha~ber (for hea~ing and foaming) is formed between the mold and the jacket. The heat insulating hood is pro~ided outsi~e the hot air jacket so that a second hot air chamb2r ~for heat retention) is formed between them. The first hot air chamber is connected to a first duct for providing hot air for heating purposes through the hot air inlet. The second hot air chamber is con-nected to a second duct for providing hot air for heat retention.
When the resin is to be heated, hot air is introduced into the first hot air chamber through the first duct. In the non-heating cycle, hot air for heat retention is introduced into the second hot air chamber through the second duct.
The apparatus of this invention has the heat insulating hood outside the hot air jacket, so that hot air is introduced into the second chamber formed between them in the cycle when the resin is not heated. Therefore, the hot air jacket does not cool but remains hot even after the molding and foaming of the resin.
This contributes to the shortening of the molding and foaming cycles.
In addition, the hot air jacket is kept hot by the hot air.
Thus, it is unnecessary to add an apparatus for heat retention and hence to provide the space for it.
The accompanying drawings which are incorporated in and con-stitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to ex-plain the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a sectional view of one embodiment of the present invention as describec in Exa LZ7~0~
Fig. 2 is a sectional view takell along the line A~ in . FigO 1. , . _ ~ ig. 3 is an enlarged sectional vie~ of t~e part indicate~
by B in Fig. 1.
Fig. 4 is a sectional view of a foamed skin obtaaned by foam slush molding using the apparatus of the present in~ention as described in Example 1.
Fig. S is a sectional view of another embodiment of the apparatus of the present invention as descrabed in Example 2.
Fi~. 6 is a sectional view of the foamed skin obtained by foam slush molding using the apparatus of the present invention ~s described in Example 2.
Fig. 7 is a schematic drawing of still another embodiment of . t:he apparatus of the present invention as described in Example 4.
Fig~ 8 is a schematic plan view of the apparatus shown in Fiq. 7.
Fig. 9 is a sec~ional view taken along the line A - A. in Fig. 7.
Fig. 10 is a sectional view taken along the line B-~ in ~iq.
7.
~ ig. 11 is a sectional view o~ the foamed skin obtained by a ~on~entional foam slush ~olding apparatus.
As s~ated above, the prior art heating and foaming of a res~n contai~ing a blowing agent by the use o hot al~ or infrared radiation tends to be inadequate for objects o~
complex shapo ~hich are n~t uniformly heated. Re~erring to Eigure ~1 of tha d~a~ingst ~or example, e~cessive foaming takes place on ~hose parts sufficie~tlr exposed to ~eat, these par~s bein~ periphQry 1 and vertical s~r~ace 2. On the other hand~
it c~a~ ba seen l:hat insuicient foa~ing ~as oc~ red on o~her parts ~ c~ not suf~lc~en~ly exposed to heat.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to preferred embodi-ments of the invention, examples of which are illustrated in the accompanying drawings.
- 6a -,/j 1~4U~ ~
Example 1 Fig. 1 shows a sectional view of one embodiment of the appa-ratus of the present invention. It shows a mold 4 for slush molding, a removable hot air jacket 5 made of an insulating mate-rial, and a gap 6 formed between the mold 4 and the hot air jack-et 5. The gap is, for example, 15 mm, and uniform throughout.
Fig. 2 shows a sectional view taken along the line A-A in Fig. 1. The external edge 7 of the hot air jacket 5 functions as the lid of the gap 6 that keeps the hot air in the jacket.
A hot air generator 8 is also shown in Fig. 1. Hot air is introduced into the gap 6 through the hose 9 and the hot air inlet 10. The hot air flows through the gap 6 at a uniform flow rate and exits at the hot air outlet 11.
The operation of the apparatus includes the following steps.
At first, the skin 12 composed of a solid PVC layer (for example, 0.3 to 0.5 mm thick) and an expandable PVC layer (for example, 0.5 to 0.8 mm thick) containing a blowing agent is formed by or-dinary slush molding. After the recovery of excess plastisol or powder, the hot air jacket 5 is positioned and hot air is intro-duced into the gap 6 so that heat is applied to the expandable PVC layer of the skin. As a result of heating, a uniformly foamed skin 3 having the foam layer, for example, 2.5 to 3.0 mm .
thick is obtained, as shown in Fig. 3 which is an enlarged sec-tional view of the part indicated by B in Fig. 1. The solid PVC
layer 13 and the expanded layer 1~ are shown in Figs. 3 and ~.
~ ~ 7 Example 2 In cases where the molded item has some parts which do not need complete expansion, the gap 6 for hot air may be partly nar-rowed, for example, to less than 5 mm, as shown in Fig. 5. The reduction of hot air by the narrowed part suppresses the foaming, as shown in Fig. 6. If the hot air jacket 5 is properly designed so that the gap gradually varies, it is possible to produce a foamed product with a soft texture.
Example 3 If hot air is introduced into the gap 6 when the hot air jacket 5 is at normal temperature, the heat of the hot air is absorbed by the jacket 5. This may be prevented by positioning the jacket 5 and passing hot air through the gap prior to the slush molding. Another way to perform efficient heating is to keep the jacket hot at all times by means of a heater built into the jacket.
Example 4 The apparatus of this example is shown in Fig. 7. The skin 31 of the resin to be heated is formed on the molding surface 30a of the mold 30. The skin is composed of a solid PVC layer (for example, 0.3 to 0.5 mm thick) fdrmed by conventional slush mold-ing and an expandable PVC layer (for example, 0.5 to 0.8 mm thick) containing a blowing agent.
The hot air jacket 32 is provided along and a certain dis-tance (for example, 5 to 20 mm) apart from the molding surface 30a of the mold 30. The heat retaining hood 33 is provided along ~ 7~a~6~ 1 and a certain distance (for example, 10 to 50 mm) apart from the hot air jacket 32. Thus, a first hot air chamber 34 (for heat-ing) is formed between the molding surface 30a of the mold 30 and the hot air jacket 32, and a second hot air chamber 35 (for heat retention) is formed between the hot air jacket 32 and the heat retaining hood 33.
The hot air jacket 32 is provided with an inlet 32a for hot air used for heating, and the heat retaining hood 33 is provided with an inlet 33a for hot air used for heat retention. Hot air introduced through the inlet 32a for heating purposes impinges upon the molding surface 30a of the mold 30 opposite to the inlet 32a. The hot air impinging upon the molding surface 30a should have a uniform pressure. For this reason, that part (including the vicinity thereof) of the mold 30 which is adjacent, e.g., op-posite to the inlet 32a for the hot air for heating purposes is recessed in the flow direction of the hot air.
The inlet 32a for the hot air for heating purposes is con-nected to a first duct 36 for said hot air for heating purposes, and the inlet 33a for the hot air ~or heat retention is connected to a second duct 37 for said heat retaining hot air. The two ducts 36 and 37 are combined into a main duct 38. At the point where the two ducts 36 and 37 are combined or at the point where the main duct 38 is branched into the two ducts, there is provid-ed a diverter valve 39. Thus, the hot air supplied through the main duct 38 is directed to either the duct 36 or the duct 37, ~¦ ~depending n the position of the valve disk 39a of the diverter I ~ ~7~`~ 1 valve 39. The forward end of the duct 36 is coaxially inserted into the forward end of the duct 37, so that they form a double duct. The reference numeral 20 indicates the hot air generator connected to the main duct 38.
As shown in Figs. 7 and 8! a sealing material 21 is inter-posed between the periphery of the mold 30 and the periphery of the hot air jacket 32, and a sealing material 22 is interposed between the periphery of the hot air jacket 32 and the periphery of the heat retaining hood 33. These sealing materials improve the air tightness of the first hot air chamber 34 (for heating) and the second hot air chamber 35 (for heat retention). The sealing materials 21 and 22 are partially cut to form the outlets ¦
23 for hot air. The number and position of the outlets 23 are properly determined to control the flow direction of hot air in the hot air chambers 34 and 35.
Figs. 9 and 10 show the detailed structures of the hot air chamber 36 for heating and the hot air chamber 37 for heat reten- ¦
tion. In this example, the diverter valve 39 is a three-way valve which diverts the flow of hot air to either the duct 36 or the duct 37. Figs. 9 and 10 show an insulating material 24 pro-vided outside the heat retaining hood 33, a support 25 to support ¦
the mold 30, hot air jacket 32 and heat retaining hood 33, and valve 2~ to control the flow rate of hot air.
The apparatus described in Example 4 operates in the follow-ing manner. At first, the mold 30 is filled with plastisol or resin powder so that a fused resin layer is formed on the molding 7 ~
surface 30a. Excess plastisol or resin powder is then recovered.
The hot air jacket 32 and the heat retaining hood 33 are posi-tioned with the mold. The valve disk 39a of the diverter valve 39 shown in Fig. 7 is switched to the position shown so that the main duct 38 communicates with the hot air duct 36. Hot air is supplied to the first hot air chamber 34, whereby the resin 31 is heated. After the heating is completed, the valve disk 39a of the diverter valve 39 is switched to the position indicated by the dotted line, so that the main duct 38 communicates with the duct 37. Hot air is supplied to the second hot air chamber 35 so that the hot air jacket 33 is heated from outside and kept hot.
The hot air introduced into the first hot air chamber 34 for 1`
heating or the second hot air chamber 35 for heat retention is discharged from the outlet 23.
It will be apparent to those skilled in the art that various modifications and variations can be made in the foam slush mold-ing apparatus of the present invention without departing from the scope or spirit of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and th r equivalents.
Claims (8)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A foam slush molding apparatus comprising:
a mold including a molding surface on which a resin is heated and fused;
a hot air jacket provided along and a predetermined distance apart from said molding surface to allow the free passage of hot air therethrough, said molding surface and said jacket forming a first hot air chamber therebetween, wherein in said first hot air chamber said resin is heated for foaming, said first hot air chamber being provided with a hot air inlet and a hot air outlet;
a heat retaining hood provided outside said hot air jacket, said hot air jacket and said heat retaining hood forming a second hot air chamber for heat retention;
a first hot air duct connected to said first hot air chamber;
a second hot air duct connected to said second hot air chamber; and switching means to divert hot air alternately and controllably to said first hot air duct and to said second hot air duct.
a mold including a molding surface on which a resin is heated and fused;
a hot air jacket provided along and a predetermined distance apart from said molding surface to allow the free passage of hot air therethrough, said molding surface and said jacket forming a first hot air chamber therebetween, wherein in said first hot air chamber said resin is heated for foaming, said first hot air chamber being provided with a hot air inlet and a hot air outlet;
a heat retaining hood provided outside said hot air jacket, said hot air jacket and said heat retaining hood forming a second hot air chamber for heat retention;
a first hot air duct connected to said first hot air chamber;
a second hot air duct connected to said second hot air chamber; and switching means to divert hot air alternately and controllably to said first hot air duct and to said second hot air duct.
2. A foam slush molding apparatus as set forth in claim 1, wherein:
said hot air inlet is provided at a first part of said first hot air chamber; and said hot air outlet is provided at a second part of said first hot air chamber opposite to said hot air inlet so that hot air uniformly flows in the hot air chamber from said inlet to said outlet.
said hot air inlet is provided at a first part of said first hot air chamber; and said hot air outlet is provided at a second part of said first hot air chamber opposite to said hot air inlet so that hot air uniformly flows in the hot air chamber from said inlet to said outlet.
3. The foam slush molding apparatus as set forth in claim 1, wherein said second hot air chamber is provided with a hot air inlet and a hot air outlet.
4. The foam slush molding apparatus as set forth in claim 1, wherein said switching means is a three-way valve.
5. The foam slush molding apparatus as set forth in claim 1, wherein said predetermined distance is uniform throughout said apparatus.
6. The foam slush molding apparatus as set forth in claim 1, wherein said predetermined distance is narrowed in at least one part of said apparatus.
7. The foam slush molding apparatus as set forth in claim 1, wherein said predetermined distance varies gradually throughout said apparatus.
8. The foam slush molding apparatus as set forth in claim 1, wherein the part of the mold which is adjacent said hot air inlet is recessed in the flow direction of the hot air, said hot air flowing in an inlet air duct positioned to allow said hot air to impinge upon said molding surface and exiting from said inlet air duct within said hot air jacket.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1986054594U JPH049143Y2 (en) | 1986-04-11 | 1986-04-11 | |
| JP60-54594 | 1986-04-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1274062A true CA1274062A (en) | 1990-09-18 |
Family
ID=12975051
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000534232A Expired CA1274062A (en) | 1986-04-11 | 1987-04-09 | Foam slush molding apparatus |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4867660A (en) |
| JP (1) | JPH049143Y2 (en) |
| CA (1) | CA1274062A (en) |
| DE (1) | DE3637272A1 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4106964C2 (en) * | 1991-03-05 | 1994-07-21 | Peguform Werke Gmbh | Device and method for producing molded skins and plastic bodies |
| DE4142109C2 (en) * | 1991-12-19 | 1995-10-12 | Krauss Maffei Ag | Device for the production of molded plastic films |
| IT1273580B (en) * | 1995-04-19 | 1997-07-08 | Ilpea Ind Spa | PROCESS FOR THE FORMATION BY REFUSAL CASTING OF ARTICLES SUCH AS FAKE LEATHER OR SIMILAR THERMO-HARD THERMOPLASTIC MATERIALS AND ELASTOMERS HAVING AT LEAST ONE EXPANDED LAYER WITH CONTROLLED AND PRE-DETERMINED THICKNESSES |
| IT1284038B1 (en) * | 1996-06-20 | 1998-05-08 | Ilpea Ind Spa | PERFECTED PROCESS FOR THE FORMING OF PRODUCTS SUCH AS FAKE LEATHER OR SIMILAR FROM THERMOPLASTIC, THERMOSET OR |
| US6082989A (en) | 1998-11-13 | 2000-07-04 | Mcnally; Douglas J. | Slush molding apparatus |
| US6284182B1 (en) | 1999-03-12 | 2001-09-04 | Konal Engineering And Equipment Inc. | Molding process employing heated fluid |
| DE10022644A1 (en) * | 2000-04-28 | 2001-10-31 | Volkswagen Ag | Twin slush skin molding process for producing vehicle instrument panels, permits variation of process parameters during all molding stages |
| US6713009B2 (en) * | 2001-09-05 | 2004-03-30 | Rotational Molding Technologies, Inc. | Method and apparatus for molding plastics with elongated metallic cores |
| ITMI20021111A1 (en) * | 2002-05-23 | 2003-11-24 | Persico Spa | ROTATIONAL MOLDING MACHINE |
| DE102007019862B4 (en) * | 2007-04-25 | 2009-05-14 | Peguform Gmbh | Mold, device and method for the production of molded skins and moldings made of plastic |
| US20090200114A1 (en) * | 2008-02-08 | 2009-08-13 | General Electric Company | Thermal management system and wind turbine incorporating same |
| KR101853240B1 (en) * | 2008-09-05 | 2018-06-04 | 헨켈 아게 운트 코. 카게아아 | Edge-encapsulated panels using high damping foam |
| GB201113655D0 (en) * | 2011-08-08 | 2011-09-21 | Surface Generation Ltd | Tool temperature control |
| DE102012103674A1 (en) * | 2012-04-26 | 2013-10-31 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | mold |
| GB201303845D0 (en) * | 2013-03-04 | 2013-04-17 | Surface Generation Ltd | Mould Tool Temperrature Control |
Family Cites Families (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2829117A (en) * | 1952-07-31 | 1958-04-01 | Lonza Electric & Chem Works | Process for making closed cell cellular bodies |
| US2958905A (en) * | 1959-02-05 | 1960-11-08 | Dow Chemical Co | Method of fabricating expandable thermoplastic resinous material |
| US3095260A (en) * | 1960-09-20 | 1963-06-25 | Ferriot Brothers Inc | Process for producing plastic articles |
| US3316339A (en) * | 1962-12-19 | 1967-04-25 | Rubbermaid Inc | Method and apparatus for molding hollow articles from resins |
| US3278658A (en) * | 1963-12-05 | 1966-10-11 | Koppers Co Inc | Process and apparatus for making shaped cellular articles from expandable thermoplastic resins |
| FR1440075A (en) * | 1965-04-14 | 1966-05-27 | Saint Gobain | Process for obtaining expanded polystyrene beads |
| US3832429A (en) * | 1966-04-13 | 1974-08-27 | Saint Gobain | Method and apparatus for the production of sheet on block of agglomerated granules of polystryrene |
| FR1481637A (en) * | 1965-08-19 | 1967-08-21 | ||
| GB1206793A (en) * | 1967-10-04 | 1970-09-30 | Dohm Plastics Machinery Ltd | Improvements in rotational casting of plastics material |
| US3941528A (en) * | 1968-09-26 | 1976-03-02 | Cotterell Robert Frederick Jos | Apparatus for moulding heat-expandable thermo-plastics material |
| US3594461A (en) * | 1969-01-21 | 1971-07-20 | Grace W R & Co | Method and apparatus for continuously molding sheets from expandable polymeric materials |
| US3584105A (en) * | 1970-01-14 | 1971-06-08 | Pekor Iron Works | Method of centrifugally forming hollow articles |
| US3709651A (en) * | 1970-09-08 | 1973-01-09 | Saint Gobain | Apparatus for the production of shaped articles of expanded cohered granules of thermoplastic material, in particular polystyrene |
| DE2117559B2 (en) * | 1971-04-10 | 1972-04-27 | Farbenfabriken Bayer Ag, 5090 Leverkusen | ROTARY CASTING FORM FOR PRODUCING HOLLOW BODIES FROM POWDER OR PASTE-SHAPED PLASTICS |
| FR2292623A1 (en) * | 1974-11-26 | 1976-06-25 | Aerospatiale | PROCESS FOR THE REALIZATION OF RESISTANT COMPOSITE STRUCTURES, IN PARTICULAR FOR AERODYNES AND STRUCTURES THUS OBTAINED |
| US4192638A (en) * | 1976-05-17 | 1980-03-11 | Gerard Lezier | Molding device having heat transfer chambers insulated from each other for molding expandable thermoplastic resin particles |
| US4331626A (en) * | 1977-09-12 | 1982-05-25 | Mccord Corporation | Method useful for rotational molding articles where successful runs are of different colors |
| US4431397A (en) * | 1978-10-23 | 1984-02-14 | Fried Robert P | Apparatus for producing molded plastic articles |
| JPS58132507A (en) * | 1982-02-02 | 1983-08-06 | Sumitomo Chem Co Ltd | Powder molding |
| US4548779A (en) * | 1982-11-15 | 1985-10-22 | Allied Corporation | Rotational molding multilayered articles |
| JPS60101014A (en) * | 1983-11-07 | 1985-06-05 | Mitsubishi Kasei Vinyl Co | Manufacture of composite foamed and molded item |
| JPS60139410A (en) * | 1983-12-27 | 1985-07-24 | Honda Motor Co Ltd | Method and apparatus for heating mold for resin molding |
| DE3514022C1 (en) * | 1985-04-18 | 1986-07-10 | Fa. Carl Freudenberg, 6940 Weinheim | Device for the mutual bonding of thermally softenable particles to a plastic body |
| US4621995A (en) * | 1985-10-18 | 1986-11-11 | Ex-Cell-O Corporation | Multiple zone heating of molds |
-
1986
- 1986-04-11 JP JP1986054594U patent/JPH049143Y2/ja not_active Expired
- 1986-10-27 US US06/923,641 patent/US4867660A/en not_active Expired - Lifetime
- 1986-11-03 DE DE19863637272 patent/DE3637272A1/en active Granted
-
1987
- 1987-04-09 CA CA000534232A patent/CA1274062A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPH049143Y2 (en) | 1992-03-06 |
| JPS62166009U (en) | 1987-10-21 |
| DE3637272C2 (en) | 1992-09-03 |
| DE3637272A1 (en) | 1987-10-15 |
| US4867660A (en) | 1989-09-19 |
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