CA2262757A1 - Injection molding form and process for producing hollow parts - Google Patents
Injection molding form and process for producing hollow parts Download PDFInfo
- Publication number
- CA2262757A1 CA2262757A1 CA002262757A CA2262757A CA2262757A1 CA 2262757 A1 CA2262757 A1 CA 2262757A1 CA 002262757 A CA002262757 A CA 002262757A CA 2262757 A CA2262757 A CA 2262757A CA 2262757 A1 CA2262757 A1 CA 2262757A1
- Authority
- CA
- Canada
- Prior art keywords
- core
- injection
- mold
- plastic
- supported
- 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
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
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/36—Moulds having means for locating or centering cores
-
- 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
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/261—Moulds having tubular mould cavities
- B29C45/2614—Moulds having tubular mould cavities for manufacturing bent tubular articles using an undercut forming mould core
-
- 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
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/0046—Details relating to the filling pattern or flow paths or flow characteristics of moulding material in the mould cavity
Abstract
This invention concerns a process for producing closed or open hollow parts out of plastics. To this effect, a core (12) or mold body which extends into the mold cavity and is attached to a form element and supported on other form elements is situated between two mold half-shells. The core is supported by one or more movable stops (13-18) which can be retracted from the mold cavity. Plastic is injected into the mold via a first injection channel (22) with the core in retained position. Subsequently the retaining stops (13-18) are retracted and the mold cavity is completely filled via a second injection channel (23, 24, 25).
Description
CA 022627~7 1999-02-08 W O 98/06556 PCT~P97/03734 Injection Molding Form and Plocess for Producing Hollow Parts The invention relates to an injection molding form and to a process for producing closed or open hollow bodies of plastic according to the preamble of the main claim as well as the preamble of the accompanying process claim.
An injection molding form for producing closed or open hollow bodies of rubber or rubber-like synthetic resin is disclosed in DE-OS 21 13 628. In this form thecore is supported by a retractable movable stop. The injection of the rubber or rubber-like material takes place at the support point. The mouth of the injection passage into the mold cavity is disposed in the area of the movable stop, for example in the form of an annular groove encompassing the free stop end within the bore in the corresponding molding. A disadvantage of this injection molding form consists in the fact that the local thickening formed by hlling the freed opening in the core must then be removed again. This necessitates a subsequent mechanical processing step.
Furthermore, DE-GM 86 22 018 discloses an apparatus for holding cores in a casting mold. This apparatus provided that spacers be disposed which fix the core in the casting mold. These spacers are rings which surround the core or ring segments which partially surround it, which are in contact with the inner wall of the casting mold cavity and are composed of a thermoplastic synthetic resin whose melting range is the same as that of the encompassing material. A
disadvantage of the arrangement of rings is that they must first be pushed onto the core, and especially in the case of irregularly shaped cores this is not possible without additional work. Moreover, these rings remain in the plastic molding which is subsequently formed and constitute a weak point since the bond between the ring and the injection molded material is not assured.
CA 022627~7 l999-02-08 W O 98/06556 PCT~EP97/03734 Also disclosed in DE-OS 39 20 100is a process and an apparatus for the injection molding of a box-like container in whose wall cavities are provided running perpendicular to its standing surface. To form the cavities, elongated spars are provided in the apparatus which are supported by longitudinally movable pins to stabilize their position. To prevent holes from remaining in thecompleted container the pins are drawn away from the spars in accordance with the level of the injection pressure prevailing in their vicinity which changes as the level of the plastic present in their area increases, until their ends are flush with the surface of the part of the apparatus out of which they protrude. A
disadvantage of this process is that, after the pins are withdrawn, the position of the core can change. The pins thus do not assure a uniform plastic structure.
The invention is therefore addressed to the problem of avoiding the aforementioned disadvantages and providing an apparatus as well as a process for the production of closed or open hollow bodies of synthetic resin, wherein post-treatment of the injection molding is unnecessary, and furthermore the coreremains in its correct position until the end of the injection molding process.
Setting out from the preambles of the parallel independent claims, this problem is solved by their characterizing features. The substantial advantage of the invention is that an injection molding form is created which is provided at the critical points with movable stops for supporting the core of the mold, while atthe same time a second injection p~ss~ge is provided in these critical areas.
According to the process, first the cavities situated between the respective supporting elements are filled through a first injection passage. Since the coreis supported any shifting of the core is not possible. Not until these cavities are nearly filled up and form a certain stabilization of the core, the stops are retracted and the rest of the cavity is filled through the second injection passage. Thus no local thickening occurs, and also the finished synthetic resin CA 022627~7 l999-02-08 part contains no weak points in the form of inserts.
In one embodiment of the invention, both several first injection passages and several second injection passages are provided. The first injection passages are advantageously arranged in the area of outside radii of the cavity structure, and the second injection passages are situated at the movable stops.
These and other features of preferred embodiments of the invention will be found not only in the claims but also in the description and drawings.
The invention will be explained hereinafter with reference to a workingembodiment.
Figure 1 shows a sectional view of an injection molding form with a supported mold core.
Figure 2 shows a schematic representation of the course of a process.
The injection molding form of Figure 1 serves for producing irregularly shaped tubes, such as those used, for example, for air intakes of internal combustion engines. It consists of a first mold half 10 and of a second mold half 11. A
basic profile molding core 12 is supported in the mold halves. In the halves arecore holding slides (stops) 13, 14, 15, 16, 17, 18. These support the core 12.
Furthermore, injection passages 19, 20, 21 and 22 are also provided in the mold halves; also, injection passages 3, 24 and 25 are situated in the area of the core-holding slides.
After the core 12 has been placed in the form, the form closed and the core-holding slides positioned in the position shown, synthetic resin material is injected in a first filling phase into the cavities 26 through the injection passages CA 022627~7 1999-02-08 19, 20,21 and 22. This synthetic resin spreads out up to the vicinity of the core-holding slides. After this first filling phase the core-holding slides are retracted and the injection passages 23, 24 and 25 are activated, that is, synthetic resinmaterial is injected through these injection passages into the cavities 27 whichremain. Since the synthetic resin material injected during the first filling phase is not yet crosslinked, an i"li",ate bond is formed between the injected materials.
The core-holding slides are flush with the inside wall of the mold halves 10 and11, so that no accumulations of material or weakening of material occur at thesepoints. After the plastic cools, the synthetic resin part is removed with the core 12. The core 12, which usually is composed of a low-melting metal alloy, is melted out in a known manner.
The schematic diagram shown in Figure 2 has an overall injection passage 28.
This leads to a rota~ valve 29 which connects this passage 28 to the main passage 30 and, after the rotary valve is turned, connects it with the main passage 31 as indicated by the broken line.
During the first filling phase the injection of the plastic takes place through the main passage 30 and the injection points 19, 20, 21 and 22. In a second phase the rotary valve is turned to the main passage 31, and then the filling of the remaining cavities is carried out through injection points 23, 24 and 25. The use of a rotary valve permits the molding to be made with a conventional injection molding machine. Therefore no special additional apparatus are needed.
An injection molding form for producing closed or open hollow bodies of rubber or rubber-like synthetic resin is disclosed in DE-OS 21 13 628. In this form thecore is supported by a retractable movable stop. The injection of the rubber or rubber-like material takes place at the support point. The mouth of the injection passage into the mold cavity is disposed in the area of the movable stop, for example in the form of an annular groove encompassing the free stop end within the bore in the corresponding molding. A disadvantage of this injection molding form consists in the fact that the local thickening formed by hlling the freed opening in the core must then be removed again. This necessitates a subsequent mechanical processing step.
Furthermore, DE-GM 86 22 018 discloses an apparatus for holding cores in a casting mold. This apparatus provided that spacers be disposed which fix the core in the casting mold. These spacers are rings which surround the core or ring segments which partially surround it, which are in contact with the inner wall of the casting mold cavity and are composed of a thermoplastic synthetic resin whose melting range is the same as that of the encompassing material. A
disadvantage of the arrangement of rings is that they must first be pushed onto the core, and especially in the case of irregularly shaped cores this is not possible without additional work. Moreover, these rings remain in the plastic molding which is subsequently formed and constitute a weak point since the bond between the ring and the injection molded material is not assured.
CA 022627~7 l999-02-08 W O 98/06556 PCT~EP97/03734 Also disclosed in DE-OS 39 20 100is a process and an apparatus for the injection molding of a box-like container in whose wall cavities are provided running perpendicular to its standing surface. To form the cavities, elongated spars are provided in the apparatus which are supported by longitudinally movable pins to stabilize their position. To prevent holes from remaining in thecompleted container the pins are drawn away from the spars in accordance with the level of the injection pressure prevailing in their vicinity which changes as the level of the plastic present in their area increases, until their ends are flush with the surface of the part of the apparatus out of which they protrude. A
disadvantage of this process is that, after the pins are withdrawn, the position of the core can change. The pins thus do not assure a uniform plastic structure.
The invention is therefore addressed to the problem of avoiding the aforementioned disadvantages and providing an apparatus as well as a process for the production of closed or open hollow bodies of synthetic resin, wherein post-treatment of the injection molding is unnecessary, and furthermore the coreremains in its correct position until the end of the injection molding process.
Setting out from the preambles of the parallel independent claims, this problem is solved by their characterizing features. The substantial advantage of the invention is that an injection molding form is created which is provided at the critical points with movable stops for supporting the core of the mold, while atthe same time a second injection p~ss~ge is provided in these critical areas.
According to the process, first the cavities situated between the respective supporting elements are filled through a first injection passage. Since the coreis supported any shifting of the core is not possible. Not until these cavities are nearly filled up and form a certain stabilization of the core, the stops are retracted and the rest of the cavity is filled through the second injection passage. Thus no local thickening occurs, and also the finished synthetic resin CA 022627~7 l999-02-08 part contains no weak points in the form of inserts.
In one embodiment of the invention, both several first injection passages and several second injection passages are provided. The first injection passages are advantageously arranged in the area of outside radii of the cavity structure, and the second injection passages are situated at the movable stops.
These and other features of preferred embodiments of the invention will be found not only in the claims but also in the description and drawings.
The invention will be explained hereinafter with reference to a workingembodiment.
Figure 1 shows a sectional view of an injection molding form with a supported mold core.
Figure 2 shows a schematic representation of the course of a process.
The injection molding form of Figure 1 serves for producing irregularly shaped tubes, such as those used, for example, for air intakes of internal combustion engines. It consists of a first mold half 10 and of a second mold half 11. A
basic profile molding core 12 is supported in the mold halves. In the halves arecore holding slides (stops) 13, 14, 15, 16, 17, 18. These support the core 12.
Furthermore, injection passages 19, 20, 21 and 22 are also provided in the mold halves; also, injection passages 3, 24 and 25 are situated in the area of the core-holding slides.
After the core 12 has been placed in the form, the form closed and the core-holding slides positioned in the position shown, synthetic resin material is injected in a first filling phase into the cavities 26 through the injection passages CA 022627~7 1999-02-08 19, 20,21 and 22. This synthetic resin spreads out up to the vicinity of the core-holding slides. After this first filling phase the core-holding slides are retracted and the injection passages 23, 24 and 25 are activated, that is, synthetic resinmaterial is injected through these injection passages into the cavities 27 whichremain. Since the synthetic resin material injected during the first filling phase is not yet crosslinked, an i"li",ate bond is formed between the injected materials.
The core-holding slides are flush with the inside wall of the mold halves 10 and11, so that no accumulations of material or weakening of material occur at thesepoints. After the plastic cools, the synthetic resin part is removed with the core 12. The core 12, which usually is composed of a low-melting metal alloy, is melted out in a known manner.
The schematic diagram shown in Figure 2 has an overall injection passage 28.
This leads to a rota~ valve 29 which connects this passage 28 to the main passage 30 and, after the rotary valve is turned, connects it with the main passage 31 as indicated by the broken line.
During the first filling phase the injection of the plastic takes place through the main passage 30 and the injection points 19, 20, 21 and 22. In a second phase the rotary valve is turned to the main passage 31, and then the filling of the remaining cavities is carried out through injection points 23, 24 and 25. The use of a rotary valve permits the molding to be made with a conventional injection molding machine. Therefore no special additional apparatus are needed.
Claims (4)
1. Process for producing closed or open hollow bodies of plastic, as for example tubes, with a core arranged in the mold cavity, fastened to a mold part and supported against other mold parts, wherein the core is supported by means of one or more movable stops retractable from the mold cavity, characterized in that the stops in the retracted position smoothly join the inner wall of the mold halves, that at least two injection channels (22, 25) are provided for the plastic and through these plastic is injected into the cavities which exist, and that after cooling of the plastic, the molded plastic part is removed with the core (12), and the core (12), which is composed of a low melting metal alloy, is melted out.
2. Injection molding form according to claim 1, characterized in that the second injection molding passage (25) and additional second (23, 24) injection passages are disposed in the area of the movable stops (13-18).
3. Process for making closed or open hollow bodies of plastics, as for example tubes with a bore inserted into the mold cavity, fastened to a mold part and supported against other mold parts, the core being supported by means of one or more movable stops withdrawable from the mold cavity, characterized in that plastic is injected through a first injection passage (22)into the form with the core (12) supported, and then the stops (13-18) are withdrawn and, through a second injection passage (25), the mold cavity is completely filled.
4. Process according to claim 3, characterized in that additional first injection passages (19, 20, 21) are provided, while the first injection passages are provided preferably at the ends of the injection molding form and at the outer arches of the part to be produced.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19631963A DE19631963C2 (en) | 1996-08-08 | 1996-08-08 | Injection mold |
| DE19631963.3 | 1996-08-08 | ||
| PCT/EP1997/003734 WO1998006556A1 (en) | 1996-08-08 | 1997-07-12 | Injection molding form and process for producing hollow parts |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2262757A1 true CA2262757A1 (en) | 1998-02-19 |
Family
ID=7802084
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002262757A Abandoned CA2262757A1 (en) | 1996-08-08 | 1997-07-12 | Injection molding form and process for producing hollow parts |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US6203745B1 (en) |
| JP (1) | JP2000516160A (en) |
| KR (1) | KR100448178B1 (en) |
| CA (1) | CA2262757A1 (en) |
| DE (1) | DE19631963C2 (en) |
| FR (1) | FR2752188B1 (en) |
| GB (1) | GB2331724B (en) |
| WO (1) | WO1998006556A1 (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6503430B1 (en) * | 2000-08-01 | 2003-01-07 | Philip Downey | Cold runner molding system |
| EP2428173B1 (en) | 2001-09-24 | 2014-07-16 | Applied Medical Resources Corporation | Obturator |
| EP1503677B1 (en) | 2002-05-16 | 2011-05-04 | Applied Medical Resources Corporation | Cone tip obturator |
| WO2005032348A2 (en) | 2003-10-03 | 2005-04-14 | Applied Medical Resources Corporation | Bladeless optical obturator |
| EP2545871B1 (en) | 2004-06-29 | 2015-02-11 | Applied Medical Resources Corporation | Insufflating optical surgical instrument |
| US7794644B2 (en) | 2005-10-05 | 2010-09-14 | Applied Medical Resources Corporation | Thin-walled optical obturator |
| EP2984993B1 (en) * | 2006-10-06 | 2019-09-11 | Applied Medical Resources Corporation | Visual insufflation port |
| EP2837344B1 (en) * | 2008-01-25 | 2016-07-13 | Applied Medical Resources Corporation | Insufflating access system |
| ES2433006T3 (en) * | 2008-04-28 | 2013-12-05 | Biedermann Technologies Gmbh & Co. Kg | Implant in the form of a rod, in particular for the stabilization of the spine, method and tool for its production |
| EP3545883B1 (en) | 2008-09-29 | 2021-01-13 | Applied Medical Resources Corporation | First-entry trocar system |
| US9254148B2 (en) | 2011-05-02 | 2016-02-09 | Applied Medical Resources Corporation | Low-profile surgical universal access port |
| WO2021025602A1 (en) * | 2019-08-07 | 2021-02-11 | Saab Ab | A mould tool assembly |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH451494A (en) * | 1966-07-15 | 1968-05-15 | Segmueller Ag | Process for the production of cup-shaped or sleeve-shaped containers made of thermoplastics by injection molding |
| DE2113628A1 (en) * | 1971-03-20 | 1972-09-28 | Continental Gummi Werke Ag | Supporting injection mould core - with movable support at opposite end from core mounting |
| US4041122A (en) * | 1976-06-01 | 1977-08-09 | International Paper Company | Process for molding of hollow articles |
| US4381275A (en) * | 1981-01-30 | 1983-04-26 | Trade Finance International | Stabilized core injection molding of plastic |
| GB8501006D0 (en) | 1985-01-16 | 1985-02-20 | Dunlop Ltd | Games racket |
| DE8622028U1 (en) * | 1986-08-16 | 1986-12-18 | Chemieschutz Gesellschaft Fuer Saeurebau Mbh, 6140 Bensheim, De | |
| US5125816A (en) * | 1988-12-02 | 1992-06-30 | Fuji Photo Film Co., Ltd. | Apparatus for molding an article in a plurality of colors |
| DE3920100A1 (en) * | 1989-02-02 | 1990-08-09 | Theysohn Friedrich Fa | Injection moulding of hollow walled chests |
| EP0381223A3 (en) * | 1989-02-02 | 1991-07-03 | Friedrich Theysohn GmbH | Method for moulding a box-shaped container by injection |
| US5240397A (en) * | 1991-10-01 | 1993-08-31 | Biomedical Polymers, Inc. | Injection molding mechanism for forming a monolithic tubular pipette |
| JP2802333B2 (en) * | 1995-01-25 | 1998-09-24 | 株式会社バンダイ | Molding equipment |
-
1996
- 1996-08-08 DE DE19631963A patent/DE19631963C2/en not_active Expired - Fee Related
-
1997
- 1997-07-12 JP JP10509321A patent/JP2000516160A/en active Pending
- 1997-07-12 GB GB9902550A patent/GB2331724B/en not_active Expired - Fee Related
- 1997-07-12 CA CA002262757A patent/CA2262757A1/en not_active Abandoned
- 1997-07-12 US US09/242,066 patent/US6203745B1/en not_active Expired - Fee Related
- 1997-07-12 KR KR10-1999-7001033A patent/KR100448178B1/en not_active IP Right Cessation
- 1997-07-12 WO PCT/EP1997/003734 patent/WO1998006556A1/en active IP Right Grant
- 1997-08-08 FR FR9710226A patent/FR2752188B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| WO1998006556A1 (en) | 1998-02-19 |
| KR20000029868A (en) | 2000-05-25 |
| JP2000516160A (en) | 2000-12-05 |
| KR100448178B1 (en) | 2004-09-10 |
| FR2752188A1 (en) | 1998-02-13 |
| DE19631963C2 (en) | 2000-03-09 |
| FR2752188B1 (en) | 1999-10-22 |
| GB2331724B (en) | 2000-09-27 |
| US6203745B1 (en) | 2001-03-20 |
| GB9902550D0 (en) | 1999-03-24 |
| DE19631963A1 (en) | 1998-02-12 |
| GB2331724A (en) | 1999-06-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |