CA2055895A1 - Article forming process, and product - Google Patents
Article forming process, and productInfo
- Publication number
- CA2055895A1 CA2055895A1 CA 2055895 CA2055895A CA2055895A1 CA 2055895 A1 CA2055895 A1 CA 2055895A1 CA 2055895 CA2055895 CA 2055895 CA 2055895 A CA2055895 A CA 2055895A CA 2055895 A1 CA2055895 A1 CA 2055895A1
- Authority
- CA
- Canada
- Prior art keywords
- container
- set forth
- thickened
- thermal gradient
- section
- 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.)
- Abandoned
Links
Landscapes
- Containers Having Bodies Formed In One Piece (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A thermoplastic container having an upper, hollow body portion and a base is provided with a decorative location ring adjoining the juncture of the body portion and the base. The process of manufacture includes establishing a predetermined thermal gradient, by way of interrupting the die casting of the container prior to cooling to the point of rigidity, and applying axial compressive force sufficient to produce outward local deformation at a desired location, to form the location ring.
A thermoplastic container having an upper, hollow body portion and a base is provided with a decorative location ring adjoining the juncture of the body portion and the base. The process of manufacture includes establishing a predetermined thermal gradient, by way of interrupting the die casting of the container prior to cooling to the point of rigidity, and applying axial compressive force sufficient to produce outward local deformation at a desired location, to form the location ring.
Description
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ARTICLE FORMING PROCESS, AND PRODUCT
TECHNICAL FIELD
This invention is directed to a process for manufactur-ing a thermoplastic container, and to containers obtained by way of the process.
BACKGROUND ART
.
In the manufacture of thermoplastic ware such as con-tainers, the use of multi axis molds enables precise die cast-ing of quite complex shapes. However, the fineness of section that may be cast, and the complexity of the form selected is constrained by flow limitations of the plastic medium, at economic production rates.
As a consequence, certain desireable features of the article in manufacture may not be readily or economically provided by existing processes.
DISCLOSURE OF INVENTION
In accordance with the present invention certain modi-fications to a molded article are obtained by providing a pre-determined thermal gradient to selected portions of the article, applying a deforming force to the selected portion of the article, and deforming the article in a first direction to a predetermined extent sufficient to achieve the desired modi-fication of form in a second direction.
In the case of a hollow container produced by molding, the preferred method includes interrupting the molding cycle prematurely, before the article is cooled to the point of rigidity in all its parts, removing it from the mold, and applying a mechanical force in deforming relation thereto, to p~roduce a desired extent of deformation at a required loca-tion, where plastic flow may be achieved.
In the case of a drinking glass of substantially cylin-drlcal form, establishment of a thermal gradient within the mold enables safe removal of the molded glass in a solidified, partially non-set condition.
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The desired thermal gradient is more readily achieved at a portion of the container where a change in section fac:Llitates the establishment of the thermal gradient.
In one embodiment the molded container is removed from the mold while still in a plastic condition adjacent the bottom of the container section, where a section of greater mass exists. The application of an axial deforming force then produces deformation both axially and laterally.
The application of an axial compressive force is readily achieved, leading to a shortening of the overall height of the container, and the generation of a protruberant ring in the still-plastic segment adjacent the bottom of the container.
Control of the thermal state of the article, and the extent and rate of the deforming force may be such that the generation of residual stresses is substantially avoided, and visible evidence of flow lines is also absent.
In one embodiment of a drinking glass in accordance with the invention, the provision of a local annular ring ad~acent the base serves to lower the centre of gravity of the glass, and provides a locating ring which greatly facilitates secure handling of the glass while distinguishing it in ~ appearance. The rings also serve to protect the highly ; finished upper surfaces of the glasses when crated for shipment, by serving as abuttments that ensure separation of the highly finished surfaces and prevents them from contacting each other.
In the case of a wine glass form of container, the local protruberance may be located in the stem, adiacent the lower surface of the bowl of the glass.
In the case of a larger container, in the form of a jug, the protruberance also is located adjacent the base, to provide a matching appearance with that of a form of drinking glass, to which the process also is applied.
.~ The subiect process may be used with a range of ; plastics materials, including acrylics, which normally demonstrate certain molding flow limitations that may preclude .
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ARTICLE FORMING PROCESS, AND PRODUCT
TECHNICAL FIELD
This invention is directed to a process for manufactur-ing a thermoplastic container, and to containers obtained by way of the process.
BACKGROUND ART
.
In the manufacture of thermoplastic ware such as con-tainers, the use of multi axis molds enables precise die cast-ing of quite complex shapes. However, the fineness of section that may be cast, and the complexity of the form selected is constrained by flow limitations of the plastic medium, at economic production rates.
As a consequence, certain desireable features of the article in manufacture may not be readily or economically provided by existing processes.
DISCLOSURE OF INVENTION
In accordance with the present invention certain modi-fications to a molded article are obtained by providing a pre-determined thermal gradient to selected portions of the article, applying a deforming force to the selected portion of the article, and deforming the article in a first direction to a predetermined extent sufficient to achieve the desired modi-fication of form in a second direction.
In the case of a hollow container produced by molding, the preferred method includes interrupting the molding cycle prematurely, before the article is cooled to the point of rigidity in all its parts, removing it from the mold, and applying a mechanical force in deforming relation thereto, to p~roduce a desired extent of deformation at a required loca-tion, where plastic flow may be achieved.
In the case of a drinking glass of substantially cylin-drlcal form, establishment of a thermal gradient within the mold enables safe removal of the molded glass in a solidified, partially non-set condition.
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The desired thermal gradient is more readily achieved at a portion of the container where a change in section fac:Llitates the establishment of the thermal gradient.
In one embodiment the molded container is removed from the mold while still in a plastic condition adjacent the bottom of the container section, where a section of greater mass exists. The application of an axial deforming force then produces deformation both axially and laterally.
The application of an axial compressive force is readily achieved, leading to a shortening of the overall height of the container, and the generation of a protruberant ring in the still-plastic segment adjacent the bottom of the container.
Control of the thermal state of the article, and the extent and rate of the deforming force may be such that the generation of residual stresses is substantially avoided, and visible evidence of flow lines is also absent.
In one embodiment of a drinking glass in accordance with the invention, the provision of a local annular ring ad~acent the base serves to lower the centre of gravity of the glass, and provides a locating ring which greatly facilitates secure handling of the glass while distinguishing it in ~ appearance. The rings also serve to protect the highly ; finished upper surfaces of the glasses when crated for shipment, by serving as abuttments that ensure separation of the highly finished surfaces and prevents them from contacting each other.
In the case of a wine glass form of container, the local protruberance may be located in the stem, adiacent the lower surface of the bowl of the glass.
In the case of a larger container, in the form of a jug, the protruberance also is located adjacent the base, to provide a matching appearance with that of a form of drinking glass, to which the process also is applied.
.~ The subiect process may be used with a range of ; plastics materials, including acrylics, which normally demonstrate certain molding flow limitations that may preclude .
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direct in~ection molding of the desired end product.
In carrying out the process, the duration of the molding cycle is shortened, such that a semi-plastic condition still exists at the desired location, adjacent a major section of the article, upon removal from the mold; preferably after rapidly removing the sprue and the flash, the article is placed in a press and a deforming load applied thereagainst, to shorten the article while causing it to bulge outwardly at a predetermined location, so as to form the desired locating ring.
A simple press, having an air cylinder to apply a predetermined load, with predetermined axial and lateral deformations has been found satisfactory.
The present invention thus provides a process for deforming a thermoplastic container to provide a permanent deformation in the shape thereof at a first portion, and in a first direction, comprising the steps of:
establishing a thermal gradient along the shape in a second direction normal to the desired first direction, to establish the temperature of the first portion in the plastic flow regime;
applying a deforming force to the container in the second direction, to produce substantially stress free deformation of the shape in the first portion and in the first direction, and cooling the container to a temperature below the plastic flow regime.
In the preferred embodiment the container shape comprises a hollow section, having a non-uniform cross section, constituting a local heat sink therefor.
In carrying out the process as described, the step of establishing a thermal gradient consists of molding the container within a mold, and removing the container from the mold, to establish the desired temperature and thermal gradient.
The above disclosed process has been carried out on a container comprising a substantially cylindrical drinking glass, having a thickened bottom portion, the deforming force . ~ .
' ' 20~589~
In carrying out the process, the duration of the molding cycle is shortened, such that a semi-plastic condition still exists at the desired location, adjacent a major section of the article, upon removal from the mold; preferably after rapidly removing the sprue and the flash, the article is placed in a press and a deforming load applied thereagainst, to shorten the article while causing it to bulge outwardly at a predetermined location, so as to form the desired locating ring.
A simple press, having an air cylinder to apply a predetermined load, with predetermined axial and lateral deformations has been found satisfactory.
The present invention thus provides a process for deforming a thermoplastic container to provide a permanent deformation in the shape thereof at a first portion, and in a first direction, comprising the steps of:
establishing a thermal gradient along the shape in a second direction normal to the desired first direction, to establish the temperature of the first portion in the plastic flow regime;
applying a deforming force to the container in the second direction, to produce substantially stress free deformation of the shape in the first portion and in the first direction, and cooling the container to a temperature below the plastic flow regime.
In the preferred embodiment the container shape comprises a hollow section, having a non-uniform cross section, constituting a local heat sink therefor.
In carrying out the process as described, the step of establishing a thermal gradient consists of molding the container within a mold, and removing the container from the mold, to establish the desired temperature and thermal gradient.
The above disclosed process has been carried out on a container comprising a substantially cylindrical drinking glass, having a thickened bottom portion, the deforming force . ~ .
' ' 20~589~
being applied axially of the drinking glass, producing the first deformation as substantially a radial outward deflection adjacent the thicker bottom portion.
The process generally includes the step of severing at least a portion of a riser or sprue from the molded glass.
The process can provide a decorative molded thermoplastic container having a body portion comprising an open topped hollow container, with a thickened section forming the bottom of the container, and a unitary thickened, outwardly protruding annular ring located adjacent the thickened section, and integral with the container.
In a preferred embodiment of the container, the thermoplastic is an acrylic resin.
It will be understood, however, that other resins may also be used.
In the case of a molded plastic drinking glass the form of the hollow container is symmetrical.
In the case of a jug, having a handle, the form of the container is asymmetrical.
In the case of the jug or a drinking glass embodiment the container annular ring is located above the container bottom.
In the case of a wine glass type of embodiment of the container the annular ring may be located below the container bottom, to form a part of the stem of the "glass".
BRIEF DESCRIPTION OF DRAWINGS
Certain embodiments of the invention are described by way of illustration, without limitation of the invention thereto, reference being made to the accompanying drawings, wherein:
Figure 1 is an elevational view, in partial section of a drinking glass prior to completion of the process;
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`: Figure 2 is an elevational view of a drinking glass after carrying out the process in accordance with the present ~ invention;
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Figure 3 is an elevational view showing a press appar-atus used in carrying out the process according to the inven-tion.
BEST MODE OF CARRYING OUT THE INVENTION
Referring to Figures 1 and 2, a thermoplastic drinking glass 10 of substantially cylindrical form has a base portion 12 thicker in section than the wall portion 13.
After subjecting the glass 10 to the presently disclos-ed process there is produced a glass 14 of reduced height, having an annular protruberant ring portion 16 adjacent the base thereof.
Referring to Figure 3, a press arrangement 20 has an air cylinder 22 and a platen 24, beneath which a glass 14 or like article may be positioned.
In the preferred embodiment an injection molded thermo-plastic article is removed somewhat prematurely from its mold, wherein the rim portion is fully and permanently solidified, while a portion of greater section is still in a plastic or semi-plastic state, such that the desired deformation zone is at such temperature that it can flow with substantially no residual stress to mar or weaken the ensuing product.
In the case of a molded acrylic embodiment, the melt temperature is normally in the 400 to 450F range, and the mold generally operates at about 110 to 130F. On premature removal of the molded article, before final solidification takes place in the mold, into an ambient room temperature of say 75F, the rate of cooling may increase. However, the mass of the article and its rate of cooling may be such that inter-mediate operations, such as the trimming of flash, and docking of the sprue may be readily carried out prior to mounting the article into the press, and carrying out the required deforma-tions.
It will be understood that the subject process may be carried out in a range of sizes and styles of container.
INDUSTRIAL APPLICABILITY
Widespread commercial use.
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The process generally includes the step of severing at least a portion of a riser or sprue from the molded glass.
The process can provide a decorative molded thermoplastic container having a body portion comprising an open topped hollow container, with a thickened section forming the bottom of the container, and a unitary thickened, outwardly protruding annular ring located adjacent the thickened section, and integral with the container.
In a preferred embodiment of the container, the thermoplastic is an acrylic resin.
It will be understood, however, that other resins may also be used.
In the case of a molded plastic drinking glass the form of the hollow container is symmetrical.
In the case of a jug, having a handle, the form of the container is asymmetrical.
In the case of the jug or a drinking glass embodiment the container annular ring is located above the container bottom.
In the case of a wine glass type of embodiment of the container the annular ring may be located below the container bottom, to form a part of the stem of the "glass".
BRIEF DESCRIPTION OF DRAWINGS
Certain embodiments of the invention are described by way of illustration, without limitation of the invention thereto, reference being made to the accompanying drawings, wherein:
Figure 1 is an elevational view, in partial section of a drinking glass prior to completion of the process;
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`: Figure 2 is an elevational view of a drinking glass after carrying out the process in accordance with the present ~ invention;
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Figure 3 is an elevational view showing a press appar-atus used in carrying out the process according to the inven-tion.
BEST MODE OF CARRYING OUT THE INVENTION
Referring to Figures 1 and 2, a thermoplastic drinking glass 10 of substantially cylindrical form has a base portion 12 thicker in section than the wall portion 13.
After subjecting the glass 10 to the presently disclos-ed process there is produced a glass 14 of reduced height, having an annular protruberant ring portion 16 adjacent the base thereof.
Referring to Figure 3, a press arrangement 20 has an air cylinder 22 and a platen 24, beneath which a glass 14 or like article may be positioned.
In the preferred embodiment an injection molded thermo-plastic article is removed somewhat prematurely from its mold, wherein the rim portion is fully and permanently solidified, while a portion of greater section is still in a plastic or semi-plastic state, such that the desired deformation zone is at such temperature that it can flow with substantially no residual stress to mar or weaken the ensuing product.
In the case of a molded acrylic embodiment, the melt temperature is normally in the 400 to 450F range, and the mold generally operates at about 110 to 130F. On premature removal of the molded article, before final solidification takes place in the mold, into an ambient room temperature of say 75F, the rate of cooling may increase. However, the mass of the article and its rate of cooling may be such that inter-mediate operations, such as the trimming of flash, and docking of the sprue may be readily carried out prior to mounting the article into the press, and carrying out the required deforma-tions.
It will be understood that the subject process may be carried out in a range of sizes and styles of container.
INDUSTRIAL APPLICABILITY
Widespread commercial use.
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Claims (10)
1. The process of deforming a thermoplastic container to provide a permanent deformation in the shape thereof at a first portion, and in a first direction, comprising the steps of:
establishing a thermal gradient along said shape in a second direction normal to said first direction, to establish the temperature of said first portion in the plastic flow regime;
applying a deforming force to said container in said second direction, to produce substantially stress free deformation of said shape in said first portion and in said first direction, and cooling said container to a temperature below said plastic flow regime.
establishing a thermal gradient along said shape in a second direction normal to said first direction, to establish the temperature of said first portion in the plastic flow regime;
applying a deforming force to said container in said second direction, to produce substantially stress free deformation of said shape in said first portion and in said first direction, and cooling said container to a temperature below said plastic flow regime.
2. The process as set forth in claim 1, said container shape comprising a hollow section, having a non-uniform cross section, constituting a local heat sink therefor.
3. The process as set forth in claim 1, wherein said step of establishing a thermal gradient consists of molding said container within a mold, and removing said container prematurely from the mold, to establish said thermal gradient.
4. The process as set forth in claim 3, said container comprising a substantially cylindrical drinking glass having a thickened bottom portion, said deforming force being applied axially of said drinking glass, producing said first deformation as substantially a radial outward deflection adjacent said bottom portion.
5. The process as set forth in claim 4, including the step of severing at least a portion of a riser (sprue?) therefrom.
6. A decorative molded thermoplastic container having a body portion comprising an open topped hollow container, with a thickened section forming the bottom of the container, and a unitary, thickened, outwardly protruding annular ring located adjacent the thickened section, and integral with the container.
7. The container as set forth in claim 6, wherein said thermoplastic is an acrylic resin.
8. The container as set forth in claim 6, wherein said hollow container is symmetrical.
9. The container as set forth in claim 8 wherein said annular ring is located above said container bottom.
10. The container as set forth in claim 8 wherein said annular ring is located below said container bottom.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US62627290A | 1990-12-12 | 1990-12-12 | |
| US07/626,272 | 1990-12-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2055895A1 true CA2055895A1 (en) | 1992-06-13 |
Family
ID=24509690
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2055895 Abandoned CA2055895A1 (en) | 1990-12-12 | 1991-11-20 | Article forming process, and product |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2055895A1 (en) |
-
1991
- 1991-11-20 CA CA 2055895 patent/CA2055895A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |