WO1995003931A1 - Verfahren zur cryogenen herstellung von blasformteilen aus kunststoff - Google Patents
Verfahren zur cryogenen herstellung von blasformteilen aus kunststoff Download PDFInfo
- Publication number
- WO1995003931A1 WO1995003931A1 PCT/EP1994/002498 EP9402498W WO9503931A1 WO 1995003931 A1 WO1995003931 A1 WO 1995003931A1 EP 9402498 W EP9402498 W EP 9402498W WO 9503931 A1 WO9503931 A1 WO 9503931A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- air
- blow
- dried
- preform
- dry
- Prior art date
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
- B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
- B29C49/42—Component parts, details or accessories; Auxiliary operations
- B29C49/64—Heating or cooling preforms, parisons or blown articles
- B29C49/66—Cooling by refrigerant introduced into the blown 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
- B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
- B29C49/42—Component parts, details or accessories; Auxiliary operations
- B29C49/46—Component parts, details or accessories; Auxiliary operations characterised by using particular environment or blow fluids other than air
- B29C2049/4602—Blowing fluids
- B29C2049/4647—Blowing fluids created by an explosive gas mixture
-
- 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
- B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
- B29C49/42—Component parts, details or accessories; Auxiliary operations
-
- 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
- B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
- B29C49/42—Component parts, details or accessories; Auxiliary operations
- B29C49/4239—Avoiding condense, e.g. on cooled mould surfaces
Definitions
- the invention relates to a method for the cryogenic production of blow molded parts from plastic according to the preamble of claim 1.
- Blow molded parts made of plastic are used in particular in the packaging industry for packaging materials of all kinds. Blow molded parts of this type are produced according to the prior art using various techniques.
- DE 21 60 854 C3 discloses a method for cooling a hollow body made of thermoplastic material produced by the blow molding process within a blow mold, in which a cooling medium consisting of air and water is quenched and injected under high pressure into a molded blow molded part, whereby an explosive adiabatic expansion of the cooling medium is caused in the hollow body and fine ice crystals form which are deposited on the wall of the blow molded part and cool it. It is clear that when water is used in the cooling medium there is an increased risk of ice crystal formation in the area of the blow mandrel or in the blow mold, with which the disadvantages mentioned above also occur. Here, too, the cycle times and the quality of the blow molded parts produced are not convincing.
- the inflation of a blow molded part is carried out in such a way that carbonic acid is introduced into the molded part via feed lines in order to inflate the blow molded part.
- a further supply line is used Coolant is led into cavities in the blow mold in order to cool or solidify the inflated blow molded part.
- the device according to DE 33 37 651 C2 has two blow mold halves with a relatively small mass, which can be enclosed by heat mold halves with a larger mass, in order to be able to cool the blow mold part located in the blow mold quickly due to the large mass of the heat mold halves.
- the cooling temperature also not being able to be set sufficiently low.
- a method is also known from DE 28 17 472 C2, in which blow-molded parts are inflated or cooled from the inside by means of a mixture of cold air and water, the disadvantages listed above arising.
- the classic ram air process with the exclusive cooling of the blow molding by the cooled tool or blow mold has its limits with regard to the coolant temperature in any case, since otherwise there must be intolerable condensation effects on the cold tool.
- the invention has for its object to propose a cryogenic process for producing blow mold parts made of plastic; in particular, a method according to the invention with improved cycle time at reduced blow mold part costs should preferably be proposed for the production of bulky blow mold parts.
- the advantages to be achieved with the invention are based on the fact that air is used as the blowing medium and is dried before being introduced into the preform. Furthermore, cryogenic, dry air is introduced into the inflated preform or the blow molding in order to cool the inflated preform or the blow molding. In addition, while the blow mold is open, the blow mold and / or the blow mandrel are flushed with, or flushed with, dry, warm air.
- the interior of the blow mold is simultaneously subjected to dry, in particular warm, air, so that the humidity of the room air cannot condense even on the cold internal contours of the blow mold, which on the one hand affects the quality the molded part surface is important and on the other hand enables lower coolant temperatures for the blow molding cooling or tool cooling.
- liquid nitrogen to be used for cooling the dry air for further uses, for example as a mixed gas or purge gas, in particular in fluorination processes, the pressure of the gaseous nitrogen formed during the cooling being adapted to the subsequent processes can.
- blowing mandrel cooling with water is generally avoidable.
- the method according to the invention enables a surprisingly short cycle time, which is impressive Is shortened, namely about 40% and more, and is exemplary in terms of reproducibility.
- the liquid nitrogen for the generation of the necessary low temperature of the dry air is first used technologically as a coolant and then as a warm dry inert gas, a significant improvement in terms of economy is achieved.
- the required shortening of the cycle time or the increase in output of the blow molding machine set up for the process according to the invention can be achieved by controlling the difference in pressures before and after the blow mold, controlling the temperature of the dry air and Control of the purge time with the dry air, the required process parameters are determined.
- the high rate of increase in the cycle time to be achieved according to the invention means that a higher nitrogen consumption in kilograms of nitrogen per kg of plastic mass is required, the optimum being specific to the molding, tool and blow molding machine.
- Compressed air can preferably also be used.
- the blow mold and the blow mandrel are flushed or flushed with dry, warm air after the one and before the subsequent blow process, while the blow mold is open, the blow mold also being flushed through the blow mandrel. By rinsing the blow mold through the blow mandrel, it is possible to keep the blow mold free of condensate as well as to keep the blow mandrel free of condensate and ice.
- FIG. 1 shows a block diagram of a system designed for the method according to the invention.
- FIG. 2 shows a partial section of the detail X from FIG. 1, which in particular shows the design of the blow dome in a sectional view.
- FIG. 1 shows a system which is suitable for carrying out the method according to the invention or a method variant of the present invention.
- An air stream in particular compressed air, is introduced into a pressure-controlled drying device 3 and dried there.
- the drying device 3 can have two adsorbers, in particular bed adsorbers, one of which is used for drying, while the other bed adsorber is regenerated.
- the regeneration can be carried out by relaxing the adsorber and simultaneously Flow can be carried out with dry air.
- the switching intervals are determined by the adsorption capacity of the adsorbent and are fixed in time.
- all types of drying devices are suitable, although tandem bed adsorbers 3 are preferred. Since the drying devices are contained in different designs in the prior art, a further detailed explanation of the drying device 3 is unnecessary.
- the air or compressed air dried in the drying device 3 is passed into a recuperator or a pre-cooler 4, where the dried air is pre-cooled.
- This precooling process is carried out in the heat exchange with a nitrogen coming from a low-temperature cooler 5, which is already slightly preheated.
- the pre-cooled and dried compressed air is then cooled in the low-temperature cooler 5 to the predetermined target temperature of about -50 ° C to about - 170 ° C, preferably -90 ° C to -170 ° C, the in the low-temperature cooler 5 in indirect heat exchange to the compressed air liquid nitrogen is evaporated and preheated, in order to then be passed to the recuperator 4 for precooling the compressed air.
- the nitrogen can be warmed up to -180 ° C to -196 ° C, or, if necessary, far beyond.
- a magnetic control valve MV1 is opened or closed with the aid of a temperature measuring point TIC1 in accordance with a target / actual value comparison.
- the temperature measured at the temperature measuring point TIC1 and the predetermined target temperature of the dried, cryogenic compressed air are used by appropriate control electronics for controlling the solenoid control valve MV1.
- the solenoid valve MVl is connected to a storage tank via a vacuum-insulated line 1 connected for liquid nitrogen. If the valve MV1 is opened, liquid nitrogen enters the low-temperature cooler 5, in which an indirect heat exchange takes place. The liquid nitrogen evaporates and heats up, while at the same time extracting the heat from the warm or pre-cooled air or compressed air. The nitrogen supply and thus the heat exchange are controlled so that the target temperature of the dried compressed air can be maintained.
- the evaporated nitrogen passes through the pre-cooler 4 and via the check valve RK1 to a buffer 9 which can be connected to the works network.
- the nitrogen can be stored here for further use.
- monitoring is also carried out via a temperature measuring point TTC2 in the line to the "buffer".
- the dry, cryogenic air extracts its thermal energy from the molded part 8 by the air heating up. At the same time, the molded part 8 is cooled.
- the pressure relief valve DMVl enables the necessary internal pressure to be set to maintain, which ensures that no contractions of the molded part 8 occur or an optimal pressure on the blowing tool 7 is accomplished, whereby the external cooling is better to use.
- the air volume can also be determined using the set differential pressure, which can be influenced by the pressure relief valve DMVl.
- valves MV3 and MV4 are closed again.
- the valve MV5 is opened to relax the air from the inflated molding 8.
- the blow mold 7 is then opened in order to release the cooled blow molding 8.
- the valve MV5 is closed again, and at the same time the valve MV6 is opened.
- dry air now flows through the dome and the inner walls of the blowing tool 7. The quantity can be determined depending on the back pressure via the pressure control valve DMV2.
- the overall geometry of the detail X of the blower dome 15 with the parts 11, 12, 13, 14 is carried out in such a way that a two-pipe system consisting of an inner pipe 14 for providing the cooling air and an outer pipe 13 for realizing the inflation or purging is present. Flushing the outer tube 13 while the tool is open prevents water from the room air from freezing to the inner nozzle of the inner tube 14, which determines the direction of the cold air. In addition, freezing of water from the room air in the exhaust pipe 10, the outer pipe 13 and the connecting pipe 11 is prevented. A narrowing of the cross-section is no longer possible.
- the blowing tool 7 can advantageously also be rinsed between the blowing processes via the blowing dome 15 in order to prevent condensation from precipitating or freezing out.
- the amount of the advantageous dry air flow according to the invention is determined in such a way that there is sufficient protection against condensation on the inner walls of the blow mold.
- By varying the amount of cold air, the cooling time and the cold air temperature it is possible to optimally adapt to the performance reserves of the reflow expander (not shown).
Landscapes
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP7505419A JPH09503456A (ja) | 1993-07-29 | 1994-07-28 | プラスチック製のブロー成形品の低温製造法 |
EP94924814A EP0712350A1 (de) | 1993-07-29 | 1994-07-28 | Verfahren zur cryogenen herstellung von blasformteilen aus kunststoff |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DEP4325516.7 | 1993-07-29 | ||
DE4325516 | 1993-07-29 | ||
DEP4425518.7 | 1994-07-19 | ||
DE4425518A DE4425518C2 (de) | 1993-07-29 | 1994-07-19 | Verfahren zur cryogenen Herstellung von Blasformteilen aus Kunststoff |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1995003931A1 true WO1995003931A1 (de) | 1995-02-09 |
Family
ID=25928158
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP1994/002498 WO1995003931A1 (de) | 1993-07-29 | 1994-07-28 | Verfahren zur cryogenen herstellung von blasformteilen aus kunststoff |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0712350A1 (de) |
JP (1) | JPH09503456A (de) |
CA (1) | CA2168242A1 (de) |
WO (1) | WO1995003931A1 (de) |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CH384193A (de) * | 1960-04-05 | 1964-11-15 | Parnall & Sons Limited | Vorrichtung zum Kühlen thermoplastischer Formteile |
US3505442A (en) * | 1967-08-22 | 1970-04-07 | Phillips Petroleum Co | Method for cooling blow molded articles |
FR2122351A1 (en) * | 1971-01-22 | 1972-09-01 | Air Liquide | Blow moulding - using chilled gas circulation or injection for accelerated cooling of mouldings |
GB1456833A (en) * | 1972-12-08 | 1976-11-24 | Hunkar Laboratories | Moulding |
US4152383A (en) * | 1976-11-26 | 1979-05-01 | Ryder Leonard B | Method for injection blow molding |
DE2817472A1 (de) * | 1978-04-21 | 1979-10-31 | Leonard B Ryder | Verfahren und vorrichtung zum formen von plastikartikeln |
-
1994
- 1994-07-28 CA CA002168242A patent/CA2168242A1/en not_active Abandoned
- 1994-07-28 JP JP7505419A patent/JPH09503456A/ja active Pending
- 1994-07-28 WO PCT/EP1994/002498 patent/WO1995003931A1/de not_active Application Discontinuation
- 1994-07-28 EP EP94924814A patent/EP0712350A1/de not_active Withdrawn
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CH384193A (de) * | 1960-04-05 | 1964-11-15 | Parnall & Sons Limited | Vorrichtung zum Kühlen thermoplastischer Formteile |
US3505442A (en) * | 1967-08-22 | 1970-04-07 | Phillips Petroleum Co | Method for cooling blow molded articles |
FR2122351A1 (en) * | 1971-01-22 | 1972-09-01 | Air Liquide | Blow moulding - using chilled gas circulation or injection for accelerated cooling of mouldings |
GB1456833A (en) * | 1972-12-08 | 1976-11-24 | Hunkar Laboratories | Moulding |
US4152383A (en) * | 1976-11-26 | 1979-05-01 | Ryder Leonard B | Method for injection blow molding |
DE2817472A1 (de) * | 1978-04-21 | 1979-10-31 | Leonard B Ryder | Verfahren und vorrichtung zum formen von plastikartikeln |
Non-Patent Citations (1)
Title |
---|
W. EGLE: "Vermeiden von Schwitzwasser auf Spritzgiess und Blaswerkzeugen", KUNSTOFFE, vol. 76, no. 1, January 1986 (1986-01-01), MüNCHEN, pages 32 - 34 * |
Also Published As
Publication number | Publication date |
---|---|
CA2168242A1 (en) | 1995-02-09 |
EP0712350A1 (de) | 1996-05-22 |
JPH09503456A (ja) | 1997-04-08 |
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