CA2213986A1 - Balanced multiple hot runner coinjection tool - Google Patents
Balanced multiple hot runner coinjection toolInfo
- Publication number
- CA2213986A1 CA2213986A1 CA002213986A CA2213986A CA2213986A1 CA 2213986 A1 CA2213986 A1 CA 2213986A1 CA 002213986 A CA002213986 A CA 002213986A CA 2213986 A CA2213986 A CA 2213986A CA 2213986 A1 CA2213986 A1 CA 2213986A1
- Authority
- CA
- Canada
- Prior art keywords
- hot runner
- runner block
- tool according
- top plate
- tool
- 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
- 238000001746 injection moulding Methods 0.000 claims abstract description 5
- 238000006073 displacement reaction Methods 0.000 claims description 8
- 239000007924 injection Substances 0.000 claims description 8
- 238000007789 sealing Methods 0.000 claims description 6
- 238000000071 blow moulding Methods 0.000 claims description 2
- 230000000284 resting effect Effects 0.000 claims 1
- 239000000155 melt Substances 0.000 abstract description 3
- 230000006835 compression Effects 0.000 abstract 1
- 238000007906 compression Methods 0.000 abstract 1
- 238000000465 moulding Methods 0.000 abstract 1
- 238000002347 injection Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000009826 distribution Methods 0.000 description 4
- 229920002994 synthetic fiber Polymers 0.000 description 4
- 238000007664 blowing Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 2
- 239000004677 Nylon Substances 0.000 description 1
- 206010040925 Skin striae Diseases 0.000 description 1
- 235000013361 beverage Nutrition 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 206010016256 fatigue Diseases 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 239000000289 melt material Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 208000024891 symptom Diseases 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
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
- B29C45/16—Making multilayered or multicoloured articles
- B29C45/1603—Multi-way nozzles specially adapted therefor
-
- 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
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C45/2725—Manifolds
-
- 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
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C45/2725—Manifolds
- B29C2045/2729—Manifolds with thermal expansion
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
- Coin-Freed Apparatuses For Hiring Articles (AREA)
- Vending Machines For Individual Products (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
Abstract
A hot runner mould for injection moulding multilayered mouldings by simultaneously injecting various plastic melts into several cavities has a hot runner block (23a-c) slidingly supported between a top plate (21) at the side of the extruder and a hot runner plate (22) at the side of the cavities. A
joining piece (24) firmly secured to said hot runner block is coupled to a feed bush (12) slidingly mounted on the top plate (21). The hot runner plate (22) can thus expand freely with temperature changes and the compression forces of the extruder do not act upon the hot runner block (23a-c) but are absorbed by the top plate (21). The feed paths for the various plastic melts change thanks to the structure in several parts of the hot runner block (23a-c) and to the controlled expansion movements of the hot runner block (23a-c) that are identical for all cavities.
joining piece (24) firmly secured to said hot runner block is coupled to a feed bush (12) slidingly mounted on the top plate (21). The hot runner plate (22) can thus expand freely with temperature changes and the compression forces of the extruder do not act upon the hot runner block (23a-c) but are absorbed by the top plate (21). The feed paths for the various plastic melts change thanks to the structure in several parts of the hot runner block (23a-c) and to the controlled expansion movements of the hot runner block (23a-c) that are identical for all cavities.
Description
~ CA 02213986 1997-08-27 Balanced Multiple Hot Runner coiniection Tool The present invention relates to a balanced multiple hot runner coinjection tool for an injection and blow-molding machine according to the preamble of claim 1.
Such tools for injection molding of multilayer parisons or preforms made of synthetic materials and, in particular PET-like materials are well known and are used mainly for the production of preforms such as are used in large quan-tities in the beverage industry for so-called PET bottles.
Extraordinarily high requirements are placed on these forming tools, because when processing PET, PEN and their copolymers, as well as nylon, particular attention must be paid to their material-specific features. Thus, for ex-ample, the processing temperature of these synthetics has proven to be particularly critical. They also react extremely sensitively to fluctuations in pressure and to shearing forces. In particular such and other parameters influence the regularity and homogenity of the layer thick-ness and density distribution within the manufactured preforms.
In the injection molding device as described in patent publication WO91/16188 special attention was paid to the length of the conveying channels and a constant temperature distribution was achieved in distribution blocks provided for that purpose. Unfortunately with this structure it is impossible to avoid a mixing of the different form masses, which can lead to unacceptable material fluctuations and blendings, especially in the manufacture of preforms for the food industry. The use of several distribution bloc~s has proven to be problematic, in particular for the adju-stment and servicing of the entire tool.
Hot runner blocks are usually secured inside the tool, i.e.
between top plate and hot runner plate such that their conveyin,g channels are aligned both on the extruder side as well as on the nozzle side, thus providing a pressure tight . CA 02213986 1997-08-27 connection. Due to the dif~erent thermal expansion of the hot runner block on the one hand, and of the top plate or hot runner plate on the other hand, intrinsic tensions occur in the tool and in particular in the hot runner block, which can rapidly lead to material fatigue symptoms such as hair cracks or even material breakage. Another type of mechanical stress o~ the hot runner block is caused by the closing pressure of the extruder on the tube-shaped fitting piece which extends through the top plate. The pulse-like conveyance of the molten synthetic material causes additional pressure stress to the hot runner block which, together with the above mentioned mechanical stress, can cause irreversible damage.
It is th,ere~ore the aim o~ the present invention to provide a balanced multiple hot runner coinjection tool in which the hot runner block is not subjected to thermally caused stress, is not mechanically strained by the mechanical clamping pressure of the extruder, and is not subjected to distortions caused by the shock-like pressure strain when the molten synthetics are pressed through. It is therefore the subject of the present invention to provide a wear-resistant tool with a stress-free hot runner bloc]c.
This is acheived by means o~ a tool according to the pream-ble of claim 1, whereby the hot runner block can therma-lly expand without stress, being slidingly supported between the top plate and the hot runner plate and is only attached in its middle by centering means, and means being provided to control the direction in which the hot runner bloc~
thermal3y expands.
In particular, the hot runner bloc~-is supported in its peripheral areas by means of displacement elements on the hot runner plate. In order to allow the hot runner block to thermally expand without stress, the tube shaped fitting piece is also slidingly supported. According to the present . . CA 02213986 1997-08-27 invention, the force exerted by the clamping pressure of the extruder on this fitting piece is absorbed by a ~eed bush. The outer edge of this feed bush lies on the top plate and thereby transmits this clamping pressure to the top plate. This feed bush is slidingly supported on the top plate in order not to impede the expansion movement of the hot runner block. In the present structure particular attention is to be paid to the fact that the conveying channels are of equal length and that they are arranged as symmetrically as possible. This balanced conveying channel arrangement effects that the shock-like pressure changes which occur when the cavities are filled essentially cancel each other out.
The present invention is more closely described with reference to the figures, in which Fig. 1 shows a cross-section through a schematic view of an injection-blow machine;
Fig. 2 shows a cross-section through a preferred ,embodiment of an inventive hot runner tool in the injection region;
Fig. 3 shows a cross-section through the center of a preferred embodiment of an inventive hot runner tool r Fig. 4 shows a longitudinal section through a preferred ~embodiment of an hot runner tool.
Figure 1 shows a cross-section through a schematic structure of an injection-blow machine with a hot runner tool 2 according to the present invention, hereinafter also called a hot runner system or, in short, tool, and a com-plementary extruder 3. The injection-blow machine essenti-ally comprises a triangular or quadrangular turn-table 7, which normally bears on each of its sides one or more core rods 8, and which is rotatable about a rotational axis A.
In this way the core rods 8 which have been covered with melt in a first position can be brought to a blowing tool (not shown) merely by rotation and can then be brought to an unloading station (not shown) by a further rotation.
Depending upon the melt material being used it is possible that a temperature control station is provided between the injection station and the blow-mold station. The schematic structure as shown in Figure 1 shows a cross-section through such an injection-blow machine at the injection station. This injection station comprises at least one extruder 3, a hot runner tool 2 and a forming device 9.
This forming device 9 essentially comprises a lower forming plate 4 and an upper forming plate 5, which result in at least one, but preferably eight cavities 6 for the production of preforms. A core rod 8 projects from the turntable 7 into each of these cavities 6. After injection into, and subsequent cooling of the hot synthetic melt in the cooled cavities 6, these are opened by means of lifting the upper forming plate 5 with the aid of a machine plate 10 along a column 11. By means of a slight lifting of the turntable 7 the melt covered core rods 8 can be lifted out of the lower forming plate 4 and can be rotated into the temperature control or blowing station. As a result of this rotation of the turntable 7, the core rods 8 of the second side are positioned over the cavities 6, and are lowered into these cavities 6 prior to closure of the forming device 9.
The purpose of the hot runner tool 2 is to distribute the plastified synthetic material over a number of cavities 6 evenly. This uniform distribution of the synthetic material is very important for the manufacture of evenly charged forms. Preforms having an uneven charging density tend to tear during blowing, and can have discolorations or opaque striae (streaks). This is why the hot runner tool 2 accor-ding to the present invention comprises temperature stabi-lized conveying channels of equal lengths between a feed bush 12 and the individual injection nozzles 13.
Figure 2 shows a cross-section through a preferred embodiment of an in~entive hot runner tool 2. Essentially this comprises a top plate 21, a hot runner plate 22 and a three-part hot runner block 23a, 23b, 23c. The upper part 23a of the hot runner block is firmly secured to a feed bush 12 by means of a heatable tube portion 24. The lower parts 23b, 23c of the hot runner block are centrally, i.e.
at the connecting location of the conveying channels, wedged to the upper part 23a of the hot runner block and are secured t:here by means of a screw 37.
The upper hot runner block part 23a is slidingly supported by the lower plate 22 by means of two support rings 25, the feed bus]h 12 lies slidingly on the top plate 21, and the tube portion 24, which is firmly secured to the feed bush 12, is slidingly clamped by means of shoulder faces 26 of the top plate 21. This arrangement allows the hot runner block 23,a-c t:o expand (at normal operating temperatures of, for exam!ple, 230~C) relative to the cooler top plate 21 and the hot runner plate 22, without causing undesirable ther-mal tensionsO In particular, with this arrangement the normal pressure force of approx. 9 tons, which is generated by the extruder, is not transmitted to-the hot runner block 23a-c, but is deviated to the top plate 21 by means of the feed bush 12. A lining 28 secures this feed bush 12.
It can b~e seen from Figures 3 and 4 that the tension-free thermal expansion of the hot runner block 23a-c is essen-tially acheived in that the upper part 23a of the hot runner block is securely supported at its center at the top plate 21 on the one hand, and at the hot runner plate 22, with the aid of a centering disk 29 and a centering ring 30 on the other hand. A thermal expansion of the upper part 23a of the hot runner block therefore leads to a symmetri-cal out~ard displacement of the tube shaped fitting pieces 24 (Figures 2, 4). An exact adjustment of the connecting location between the extruder 3 and the feed bush 12 can easily k,e achieved. The division of the lower parts 23b and 23c allows the compensation of the differing degrees of thermal expansion caused by the different design of the upper part 23a and the lower parts 23b, 23c. In this way the lower parts 23b, 23c, which are rigidly attached at the channel connecting location, can expand independently of each other.
This is acheived in particular by the fact that the lower j parts 23b, c of the hot runner bloc~, as shown in Figure 2, are provided with abuttment plugs 20 on the extruder side, and slidingly rest on sealing plugs 80 on the nozzle side.
These plugs 20, 80 are preferably arranged in the region of the needle sl~ut-off arrangement 31. Thus, for example, the abuttment plug 20 has a bore hole through which the needle 32 of the needle shut-off arrangement extends, said bore hole being large enough not to block said needle 32 when the hot runner block thermally expands. In contrast the sealing plug 80 is inserted in the nozzle 13 clamped in the hot runner plate 22. At operating temperature this arran-gement permi~s a calculatable thermal displacement of the lower hot runner blocks 23b, c, and at the same time leads to a pressure tight sealing between the conveying channels 14 and the nozzle channels 15.
As can be seen from Figure 2, it has proven particularly advantageous to arrange a needle shut-off arrangement 31 in a recess or cavity in the top plate 21, said recess serving as a pneumatic cylinder. In particular, the needle shut-off arrangement 31 comprises a first plunger 33 bearing the needle 32, over which first plunger a second plunger 34 is movably inserted. A hermetically sealing cylinder lid 35 pressure-tightly seals this recess. Appropriately arranged pressure lines 41, 43 and 44 enable the individual plungers and thus the needle 32 to be brought into the desired pos ition .
In a pre.ferred embodiment of the invention each pressure line hac~ a differently high pressure. Thus, for example, the outer pressure line 44 can admit lo bar, the middle pressure line 43 can admit 6 bar and the inner pressure line 41 can admit 6 bar. By suitably changing the pressure in the individual pressure lines the nozzle needle 32 can be moved as required to regulate the nozzle-exit openings.
It is understood that the exemplary description of the tool construction can be modified by those skilled in the art and with,out particular inventive know-how. Thus, for example, the number of displacement or guiding elements can be modified to suit the particular dimensions of the hot runner block, or other materials with suitable heat capaci-ty or conductivity can be chosen. In particular, the number of nozzles can be modified to suit the requirements of the form parts, or several conveying channels can be used for the manufacture of multi-layer preforms.
Such tools for injection molding of multilayer parisons or preforms made of synthetic materials and, in particular PET-like materials are well known and are used mainly for the production of preforms such as are used in large quan-tities in the beverage industry for so-called PET bottles.
Extraordinarily high requirements are placed on these forming tools, because when processing PET, PEN and their copolymers, as well as nylon, particular attention must be paid to their material-specific features. Thus, for ex-ample, the processing temperature of these synthetics has proven to be particularly critical. They also react extremely sensitively to fluctuations in pressure and to shearing forces. In particular such and other parameters influence the regularity and homogenity of the layer thick-ness and density distribution within the manufactured preforms.
In the injection molding device as described in patent publication WO91/16188 special attention was paid to the length of the conveying channels and a constant temperature distribution was achieved in distribution blocks provided for that purpose. Unfortunately with this structure it is impossible to avoid a mixing of the different form masses, which can lead to unacceptable material fluctuations and blendings, especially in the manufacture of preforms for the food industry. The use of several distribution bloc~s has proven to be problematic, in particular for the adju-stment and servicing of the entire tool.
Hot runner blocks are usually secured inside the tool, i.e.
between top plate and hot runner plate such that their conveyin,g channels are aligned both on the extruder side as well as on the nozzle side, thus providing a pressure tight . CA 02213986 1997-08-27 connection. Due to the dif~erent thermal expansion of the hot runner block on the one hand, and of the top plate or hot runner plate on the other hand, intrinsic tensions occur in the tool and in particular in the hot runner block, which can rapidly lead to material fatigue symptoms such as hair cracks or even material breakage. Another type of mechanical stress o~ the hot runner block is caused by the closing pressure of the extruder on the tube-shaped fitting piece which extends through the top plate. The pulse-like conveyance of the molten synthetic material causes additional pressure stress to the hot runner block which, together with the above mentioned mechanical stress, can cause irreversible damage.
It is th,ere~ore the aim o~ the present invention to provide a balanced multiple hot runner coinjection tool in which the hot runner block is not subjected to thermally caused stress, is not mechanically strained by the mechanical clamping pressure of the extruder, and is not subjected to distortions caused by the shock-like pressure strain when the molten synthetics are pressed through. It is therefore the subject of the present invention to provide a wear-resistant tool with a stress-free hot runner bloc]c.
This is acheived by means o~ a tool according to the pream-ble of claim 1, whereby the hot runner block can therma-lly expand without stress, being slidingly supported between the top plate and the hot runner plate and is only attached in its middle by centering means, and means being provided to control the direction in which the hot runner bloc~
thermal3y expands.
In particular, the hot runner bloc~-is supported in its peripheral areas by means of displacement elements on the hot runner plate. In order to allow the hot runner block to thermally expand without stress, the tube shaped fitting piece is also slidingly supported. According to the present . . CA 02213986 1997-08-27 invention, the force exerted by the clamping pressure of the extruder on this fitting piece is absorbed by a ~eed bush. The outer edge of this feed bush lies on the top plate and thereby transmits this clamping pressure to the top plate. This feed bush is slidingly supported on the top plate in order not to impede the expansion movement of the hot runner block. In the present structure particular attention is to be paid to the fact that the conveying channels are of equal length and that they are arranged as symmetrically as possible. This balanced conveying channel arrangement effects that the shock-like pressure changes which occur when the cavities are filled essentially cancel each other out.
The present invention is more closely described with reference to the figures, in which Fig. 1 shows a cross-section through a schematic view of an injection-blow machine;
Fig. 2 shows a cross-section through a preferred ,embodiment of an inventive hot runner tool in the injection region;
Fig. 3 shows a cross-section through the center of a preferred embodiment of an inventive hot runner tool r Fig. 4 shows a longitudinal section through a preferred ~embodiment of an hot runner tool.
Figure 1 shows a cross-section through a schematic structure of an injection-blow machine with a hot runner tool 2 according to the present invention, hereinafter also called a hot runner system or, in short, tool, and a com-plementary extruder 3. The injection-blow machine essenti-ally comprises a triangular or quadrangular turn-table 7, which normally bears on each of its sides one or more core rods 8, and which is rotatable about a rotational axis A.
In this way the core rods 8 which have been covered with melt in a first position can be brought to a blowing tool (not shown) merely by rotation and can then be brought to an unloading station (not shown) by a further rotation.
Depending upon the melt material being used it is possible that a temperature control station is provided between the injection station and the blow-mold station. The schematic structure as shown in Figure 1 shows a cross-section through such an injection-blow machine at the injection station. This injection station comprises at least one extruder 3, a hot runner tool 2 and a forming device 9.
This forming device 9 essentially comprises a lower forming plate 4 and an upper forming plate 5, which result in at least one, but preferably eight cavities 6 for the production of preforms. A core rod 8 projects from the turntable 7 into each of these cavities 6. After injection into, and subsequent cooling of the hot synthetic melt in the cooled cavities 6, these are opened by means of lifting the upper forming plate 5 with the aid of a machine plate 10 along a column 11. By means of a slight lifting of the turntable 7 the melt covered core rods 8 can be lifted out of the lower forming plate 4 and can be rotated into the temperature control or blowing station. As a result of this rotation of the turntable 7, the core rods 8 of the second side are positioned over the cavities 6, and are lowered into these cavities 6 prior to closure of the forming device 9.
The purpose of the hot runner tool 2 is to distribute the plastified synthetic material over a number of cavities 6 evenly. This uniform distribution of the synthetic material is very important for the manufacture of evenly charged forms. Preforms having an uneven charging density tend to tear during blowing, and can have discolorations or opaque striae (streaks). This is why the hot runner tool 2 accor-ding to the present invention comprises temperature stabi-lized conveying channels of equal lengths between a feed bush 12 and the individual injection nozzles 13.
Figure 2 shows a cross-section through a preferred embodiment of an in~entive hot runner tool 2. Essentially this comprises a top plate 21, a hot runner plate 22 and a three-part hot runner block 23a, 23b, 23c. The upper part 23a of the hot runner block is firmly secured to a feed bush 12 by means of a heatable tube portion 24. The lower parts 23b, 23c of the hot runner block are centrally, i.e.
at the connecting location of the conveying channels, wedged to the upper part 23a of the hot runner block and are secured t:here by means of a screw 37.
The upper hot runner block part 23a is slidingly supported by the lower plate 22 by means of two support rings 25, the feed bus]h 12 lies slidingly on the top plate 21, and the tube portion 24, which is firmly secured to the feed bush 12, is slidingly clamped by means of shoulder faces 26 of the top plate 21. This arrangement allows the hot runner block 23,a-c t:o expand (at normal operating temperatures of, for exam!ple, 230~C) relative to the cooler top plate 21 and the hot runner plate 22, without causing undesirable ther-mal tensionsO In particular, with this arrangement the normal pressure force of approx. 9 tons, which is generated by the extruder, is not transmitted to-the hot runner block 23a-c, but is deviated to the top plate 21 by means of the feed bush 12. A lining 28 secures this feed bush 12.
It can b~e seen from Figures 3 and 4 that the tension-free thermal expansion of the hot runner block 23a-c is essen-tially acheived in that the upper part 23a of the hot runner block is securely supported at its center at the top plate 21 on the one hand, and at the hot runner plate 22, with the aid of a centering disk 29 and a centering ring 30 on the other hand. A thermal expansion of the upper part 23a of the hot runner block therefore leads to a symmetri-cal out~ard displacement of the tube shaped fitting pieces 24 (Figures 2, 4). An exact adjustment of the connecting location between the extruder 3 and the feed bush 12 can easily k,e achieved. The division of the lower parts 23b and 23c allows the compensation of the differing degrees of thermal expansion caused by the different design of the upper part 23a and the lower parts 23b, 23c. In this way the lower parts 23b, 23c, which are rigidly attached at the channel connecting location, can expand independently of each other.
This is acheived in particular by the fact that the lower j parts 23b, c of the hot runner bloc~, as shown in Figure 2, are provided with abuttment plugs 20 on the extruder side, and slidingly rest on sealing plugs 80 on the nozzle side.
These plugs 20, 80 are preferably arranged in the region of the needle sl~ut-off arrangement 31. Thus, for example, the abuttment plug 20 has a bore hole through which the needle 32 of the needle shut-off arrangement extends, said bore hole being large enough not to block said needle 32 when the hot runner block thermally expands. In contrast the sealing plug 80 is inserted in the nozzle 13 clamped in the hot runner plate 22. At operating temperature this arran-gement permi~s a calculatable thermal displacement of the lower hot runner blocks 23b, c, and at the same time leads to a pressure tight sealing between the conveying channels 14 and the nozzle channels 15.
As can be seen from Figure 2, it has proven particularly advantageous to arrange a needle shut-off arrangement 31 in a recess or cavity in the top plate 21, said recess serving as a pneumatic cylinder. In particular, the needle shut-off arrangement 31 comprises a first plunger 33 bearing the needle 32, over which first plunger a second plunger 34 is movably inserted. A hermetically sealing cylinder lid 35 pressure-tightly seals this recess. Appropriately arranged pressure lines 41, 43 and 44 enable the individual plungers and thus the needle 32 to be brought into the desired pos ition .
In a pre.ferred embodiment of the invention each pressure line hac~ a differently high pressure. Thus, for example, the outer pressure line 44 can admit lo bar, the middle pressure line 43 can admit 6 bar and the inner pressure line 41 can admit 6 bar. By suitably changing the pressure in the individual pressure lines the nozzle needle 32 can be moved as required to regulate the nozzle-exit openings.
It is understood that the exemplary description of the tool construction can be modified by those skilled in the art and with,out particular inventive know-how. Thus, for example, the number of displacement or guiding elements can be modified to suit the particular dimensions of the hot runner block, or other materials with suitable heat capaci-ty or conductivity can be chosen. In particular, the number of nozzles can be modified to suit the requirements of the form parts, or several conveying channels can be used for the manufacture of multi-layer preforms.
Claims (12)
1. Balanced multiple hot runner coinjection tool for an injection and blow-molding machine, said tool (2) comprising a top plate (21), a hot runner plate (22) and a hot runner block (23a-c), as well as a tube shaped portion (24) for connecting the hot runner block with an extruder, characterized in that the tube shaped portion (24) is secured eccentrically to the hot runner block (23a-c) and the hot runner block (23a-c) is slidingly supported by means (20, 25, 26, 30) between the top plate (21) and the hot runner plate (22) in order to allow a strain-free thermal expansion, and is secured only in its center by centering means (29, 30), and that means (27) are provided to control the direction of thermal expansion of the hot runner block (23a-c).
2. Tool according to claim 1, characterized in that the centering means (29, 30) comprise a centering disk (29) being attached to the top plate (21), and a centering ring (30) resting both in the hot runner plate (22) and in the hot runner block (23a).
3. Tool according to claims 1 or 2, characterized in that the means to slidingly support the hot runner block (23a-c) comprise peripherally arranged displacement elements, in particular displacement rings (25).
4. Tool according to claim 3, characterized in that the displacement elements lie in the axis of the tube shaped portion (24).
5. Tool according to claims 1 to 4, characterized in that the means (25, 27) for controlling the thermal expansion direction of the hot runner block (23a-c) comprise at least two peripherally arranged guiding elements, in particular pins (27) lying in a groove.
6. Tool according to claim 4 or 5, characterized in that the guiding elements (27) are combined with the displacement elements (25).
7. Tool according to claims 1 to 6, characterized in that the tube shaped portion (24) and the hot runner block (23a-c) are firmly secured to each other and that said tube shaped portion (24) is slidingly borne on the top plate (21).
8. Tool according to claims 1 to 7, characterized in that a feed bush (12) is provided, which is preferably connected by means of a radial seal with the tube shaped portion (24) and is slidingly supported by the top plate (21).
9. Tool according to claims 1 to 8, characterized in that displaceable sealing plugs (80) are provided, which pressure tightly connect the conveying channels (14) in the hot runner block and the nozzle channels (15) in the nozzle (13) at operating temperature.
10. Tool according to claims 1 to 9, characterized in that displaceable abuttment plugs (20) are provided.
11. Tool according to claims 1 to 10, characterized in that a needle shut-off arrangement (31) is provided.
12. Tool according to claim 11, characterized in that the needle of the needle shut-off-arrangment (31) is guided through the abuttment plug (20) and the sealing plug (80).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH00548/95A CH688855A5 (en) | 1995-02-27 | 1995-02-27 | Balanced multiple hot runner coinjection tool. |
| CH548/95-2 | 1995-02-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2213986A1 true CA2213986A1 (en) | 1996-09-06 |
Family
ID=4189542
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002213986A Abandoned CA2213986A1 (en) | 1995-02-27 | 1996-02-27 | Balanced multiple hot runner coinjection tool |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0812253B1 (en) |
| JP (1) | JPH11500674A (en) |
| AT (1) | ATE202032T1 (en) |
| CA (1) | CA2213986A1 (en) |
| CH (1) | CH688855A5 (en) |
| DE (1) | DE59607086D1 (en) |
| WO (1) | WO1996026823A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103171094A (en) * | 2013-04-12 | 2013-06-26 | 昆山腾宇鑫金属制品有限公司 | Die |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4588367A (en) * | 1984-07-16 | 1986-05-13 | Husky Injection Molding Systems Ltd. | Hot runner manifold for injection molding machine |
| DE8709724U1 (en) * | 1987-07-15 | 1987-09-10 | Plastic-Service GmbH, 6800 Mannheim | Hot runner injection molding tool |
| CH685237A5 (en) * | 1993-10-06 | 1995-05-15 | Otto Hofstetter Ag Werkzeug Un | Injection molding mold. |
-
1995
- 1995-02-27 CH CH00548/95A patent/CH688855A5/en not_active IP Right Cessation
-
1996
- 1996-02-27 WO PCT/CH1996/000061 patent/WO1996026823A1/en active IP Right Grant
- 1996-02-27 CA CA002213986A patent/CA2213986A1/en not_active Abandoned
- 1996-02-27 AT AT96902206T patent/ATE202032T1/en not_active IP Right Cessation
- 1996-02-27 EP EP96902206A patent/EP0812253B1/en not_active Expired - Lifetime
- 1996-02-27 DE DE59607086T patent/DE59607086D1/en not_active Expired - Fee Related
- 1996-02-27 JP JP8525933A patent/JPH11500674A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE59607086D1 (en) | 2001-07-19 |
| CH688855A5 (en) | 1998-04-30 |
| JPH11500674A (en) | 1999-01-19 |
| WO1996026823A1 (en) | 1996-09-06 |
| ATE202032T1 (en) | 2001-06-15 |
| EP0812253B1 (en) | 2001-06-13 |
| EP0812253A1 (en) | 1997-12-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |