CA2476712A1 - Method for injection molding and injection molding machine therefor - Google Patents
Method for injection molding and injection molding machine therefor Download PDFInfo
- Publication number
- CA2476712A1 CA2476712A1 CA 2476712 CA2476712A CA2476712A1 CA 2476712 A1 CA2476712 A1 CA 2476712A1 CA 2476712 CA2476712 CA 2476712 CA 2476712 A CA2476712 A CA 2476712A CA 2476712 A1 CA2476712 A1 CA 2476712A1
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- Prior art keywords
- assembly
- injection
- plasticization
- pair
- assemblies
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- 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.)
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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
- B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
- B29C45/53—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston
- B29C45/54—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw
-
- 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
- B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
- B29C45/53—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston
- B29C45/54—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw
- B29C2045/545—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw alternately operating injection plungers
-
- 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
- B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
- B29C45/53—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston
- B29C45/54—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw
- B29C2045/547—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw continuously rotating plasticising screw cooperating with a single injection plunger
-
- 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
- B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
- B29C45/53—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston
- B29C45/54—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw
- B29C2045/548—Reciprocating plasticising screws
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
Abstract
The invention comprises a plasticization assembly, adapted to receive, masticate and plasticate a pre-established quantity of synthetic resinous material. The plasticization assembly is flanked by and interconnected with a pair of injection assemblies, so that while one of the pair of injection assemblies communicates with the plasticization assembly to receive the synthetic resinous material, the other one forcibly expels the synthetic resinous material, into a molding assembly.
Furthermore, an interconnecting assembly is used for providing a communication between the plasticization assembly and each one of the pair of injection assemblies, alternatively, and a communication between one of the pair of injection assemblies, which is not in communication with the plasticization assembly, and a molding assembly.
Furthermore, an interconnecting assembly is used for providing a communication between the plasticization assembly and each one of the pair of injection assemblies, alternatively, and a communication between one of the pair of injection assemblies, which is not in communication with the plasticization assembly, and a molding assembly.
Description
TITLE: METHOD FOR INJECTION MOLDING AND INJECTION MOLDING
MACHINE THEREFOR
I. Background of the Invention 1. Field of the invention The present invention relates generally to methods and machines for injection molding.
More specifically, it relates to a method for injection molding and injection molding machines therefor, the former and the latter being based on the continuous rotation, without rectilinear reciprocating displacement, of the plasticizing screw.
MACHINE THEREFOR
I. Background of the Invention 1. Field of the invention The present invention relates generally to methods and machines for injection molding.
More specifically, it relates to a method for injection molding and injection molding machines therefor, the former and the latter being based on the continuous rotation, without rectilinear reciprocating displacement, of the plasticizing screw.
2. Description of the state of the art As it is known in the field of injection molding processes and machines, the synthetic resinous material is usually supplied in a particulate feedstock. The latter is heated, masticated and plasticated into a moldable consistency and, then, is forced into one or more molding cavities. As it is also known, when dealing with hygroscopic materials in particulate form, it is required to pass those materials through a separate pre-drying apparatus, before entering into an injection molding machinf:. In the pre-drying apparatus the particulate material is exposed to a dry heat, for a predetermined period of time, at a temperature below the material melting temperature. This pre-drying operation is necessary, since water, present in the particulate material, vaporizes during the plasticization phase, forming pockets of volatilized substances.
The above situation leads to defects, such as, for example, polymer degradation and diminished physical material properties of the molded product. Moreover, surface defects, such as loss of gloss arid voids, sometimes occur in 'the molded product. These defects can not only alter the commercial aspect of the products, but also, directly affect the physical properties of the molded products.
Attempts have been made in the past to overcome, or, at least, alleviate the above essential drawbacks. Thus, for example, United States Patent No. 6,187,229, granted Feb.
13, 2001, to Kiyoto et al. for a "Process for Molding Information Recording Disks"
discloses a molding process, wherein plasticization, injection and filing of synthetic resinous material which are carried out in separate cylinders. A synthetic resinous material, such as polycarbonate, is supplied, with out pre-drying, to an injection molding machine, for a first time molding. While synthetic resinous material is masticated and plasticated by the machine, certain components are heated. Thus, they become volatile and can be exhausted through a vent port.
A main disadvantage characterizes the forgoing process. This is due to the fact that the synthetic resinous material is extruded into an injection cylinder and then transferred, under high pressure, to a mold, while the plasticizing screw remains stationary, allowing a pooling of melted material. When the plasticizing screw resumes rotating, the pool of melted material is conveyed, at a relatively high speed, along the plasticizing screw. A
surge causing vent bleed is formed. Vent bleed will cause a solidification of the plasticated material in a vent opening and, thereby, partially or wholly, will block the latter. When this occurs, the subsequent release of volatilized material from the vent opening is severely inhibited, if not actually prevented.
United States Patent No. 6,234,659 granted May 22, 2001, to Takashima et al., for a "Surge Suppresser for Vented Injection Molding Machine Screw" describes a machine operating without pre-drying. The plasticizing machine includes a two-stage plasticizing screw, rotatably and reciprocably mounted within a barrel. A surge suppresser, provided between the first and second stages, comprises an integral protrusion of the plasticizing screw root and a deep channel section, the latter following the above integral protrusion.
The surge suppresser prevents the surge of molten material into the vent area, upon the resumption of the plasticizing screw rotation, thereby allowing faster recovery and preventing bleeding of plasticized material from the vent opening. The main disadvantage of the above surge suppresser used with a molding machine plasticizing screw resides in the following: this design requires a support for the increased length of the two-stage plasticizing screw, in order to obtain an appropriate seal in the second stage of the plasticizing screw. Furthermore, the reciprocating nature of the plasticizing screw within the barrel limits the range of shot size. Also, the surge suppressor must be adapted to the viscosity of the melted material.
II. Summary of the Invention Accordingly, there is a need for an improved method and apparatus.
It is a first objective of the present invention to develop, based on a new method, a simple to operate, reliable, with a long service life, injection molding machine.
It is a second objective of the present invention to elaborate a method and design an apparatus that allows the use of non pre-dried synthetic resinous material.
It is a third objective of the present invention to obtain a wide range of shot sizes, while preventing vent bleed.
Broadly stating, the injection molding machine, according to the present invention, comprises the following main assemblies:
- a plasticization assembly adapted to receive, masticate and plasticate a pre-established quantity of synthetic resinous material, the plasticization assembly being flanked by - a pair of injection assemblies communicating with the plasticization assembly, so that while one of the pair of injection assemblies communicates with the plasticization assembly to receive the synthetic resinous material, already masticated and plasticated, the other one of the pair of injection assemblies forcibly expels said synthetic resinous material, already masticated and plasticated, into a molding assembly;
- an interconnecting assembly for providing - a communication between the plasticization assembly and each one of the pair of injection assemblies, alternatively, and - a communication between one of the pair of injection assemblies, which is not in communication with the plasticization assembly, and the molding assembly;
- a common base incorporating a lower stationary base and an upper moving base, the latter being used - to support and - alternatively translate the plasticization assembly and the pair of injection assemblies on the lower stationary base; and - a translating assembly for alternatively translating the upper moving base with respect to the lower stationary base and the molding assembly.
In one aspect of this invention, the plasticization assembly comprises a cylindrical-housing subassembly incorporating a two stage plasticizing screw that rotates continuously about its longitudinal axis of symmetry, without any rectilinear displacement; thus, the pre-established quantity of synthetic resinous material is transformed and advanced. The two stage plasticizing screw is constituted by a thread having a constant external diameter, commensurate to cooperate with an internal diameter of the cylindrical-housing subassembly, and a variable root diameter. In order to accomplish a two stage plasticizing operation, the variable root diameter basically increases from a minimum to a maximum along a first stage, starting from one extremity, proximate to a drive end to an end of this stage. Along a second stage the root diameter basically replicates the first stage by increasing from the minimum to the maximum diameter. The plasticizing assembly further comprises band-heaters, mounted around the cylindrical-housing subassembly, respectively its external surface; a hopper connected to a feed port of the cylindrical-housing subassembly, wherein synthetic resinous material is discharged; an inlet for introducing an inert gas into the cylindrical-housing subassembly communicating with the feed port; an exhaust vent devise connecting the interior of the cylindrical-housing subassembly with the environment; and an electrical motor-mechanical transmission unit being coupled to the two stage plasticizing screw.
In another aspect of the present invention, each of the injection assemblies comprises a stepped body that incorporates an injection cylinder, coaxial with an actuating cylinder.
The injection cylinder has a diameter relatively smaller than the diameter of the actuating cylinder, and is usually provided with heating elements. A plunger is located within the injection cylinder, while a piston is located in the actuating cylinder. A rod conveniently interconnects the plunger with the piston, and under the pressure of a fluid, the piston is displaced towards the injection cylinder.
The above situation leads to defects, such as, for example, polymer degradation and diminished physical material properties of the molded product. Moreover, surface defects, such as loss of gloss arid voids, sometimes occur in 'the molded product. These defects can not only alter the commercial aspect of the products, but also, directly affect the physical properties of the molded products.
Attempts have been made in the past to overcome, or, at least, alleviate the above essential drawbacks. Thus, for example, United States Patent No. 6,187,229, granted Feb.
13, 2001, to Kiyoto et al. for a "Process for Molding Information Recording Disks"
discloses a molding process, wherein plasticization, injection and filing of synthetic resinous material which are carried out in separate cylinders. A synthetic resinous material, such as polycarbonate, is supplied, with out pre-drying, to an injection molding machine, for a first time molding. While synthetic resinous material is masticated and plasticated by the machine, certain components are heated. Thus, they become volatile and can be exhausted through a vent port.
A main disadvantage characterizes the forgoing process. This is due to the fact that the synthetic resinous material is extruded into an injection cylinder and then transferred, under high pressure, to a mold, while the plasticizing screw remains stationary, allowing a pooling of melted material. When the plasticizing screw resumes rotating, the pool of melted material is conveyed, at a relatively high speed, along the plasticizing screw. A
surge causing vent bleed is formed. Vent bleed will cause a solidification of the plasticated material in a vent opening and, thereby, partially or wholly, will block the latter. When this occurs, the subsequent release of volatilized material from the vent opening is severely inhibited, if not actually prevented.
United States Patent No. 6,234,659 granted May 22, 2001, to Takashima et al., for a "Surge Suppresser for Vented Injection Molding Machine Screw" describes a machine operating without pre-drying. The plasticizing machine includes a two-stage plasticizing screw, rotatably and reciprocably mounted within a barrel. A surge suppresser, provided between the first and second stages, comprises an integral protrusion of the plasticizing screw root and a deep channel section, the latter following the above integral protrusion.
The surge suppresser prevents the surge of molten material into the vent area, upon the resumption of the plasticizing screw rotation, thereby allowing faster recovery and preventing bleeding of plasticized material from the vent opening. The main disadvantage of the above surge suppresser used with a molding machine plasticizing screw resides in the following: this design requires a support for the increased length of the two-stage plasticizing screw, in order to obtain an appropriate seal in the second stage of the plasticizing screw. Furthermore, the reciprocating nature of the plasticizing screw within the barrel limits the range of shot size. Also, the surge suppressor must be adapted to the viscosity of the melted material.
II. Summary of the Invention Accordingly, there is a need for an improved method and apparatus.
It is a first objective of the present invention to develop, based on a new method, a simple to operate, reliable, with a long service life, injection molding machine.
It is a second objective of the present invention to elaborate a method and design an apparatus that allows the use of non pre-dried synthetic resinous material.
It is a third objective of the present invention to obtain a wide range of shot sizes, while preventing vent bleed.
Broadly stating, the injection molding machine, according to the present invention, comprises the following main assemblies:
- a plasticization assembly adapted to receive, masticate and plasticate a pre-established quantity of synthetic resinous material, the plasticization assembly being flanked by - a pair of injection assemblies communicating with the plasticization assembly, so that while one of the pair of injection assemblies communicates with the plasticization assembly to receive the synthetic resinous material, already masticated and plasticated, the other one of the pair of injection assemblies forcibly expels said synthetic resinous material, already masticated and plasticated, into a molding assembly;
- an interconnecting assembly for providing - a communication between the plasticization assembly and each one of the pair of injection assemblies, alternatively, and - a communication between one of the pair of injection assemblies, which is not in communication with the plasticization assembly, and the molding assembly;
- a common base incorporating a lower stationary base and an upper moving base, the latter being used - to support and - alternatively translate the plasticization assembly and the pair of injection assemblies on the lower stationary base; and - a translating assembly for alternatively translating the upper moving base with respect to the lower stationary base and the molding assembly.
In one aspect of this invention, the plasticization assembly comprises a cylindrical-housing subassembly incorporating a two stage plasticizing screw that rotates continuously about its longitudinal axis of symmetry, without any rectilinear displacement; thus, the pre-established quantity of synthetic resinous material is transformed and advanced. The two stage plasticizing screw is constituted by a thread having a constant external diameter, commensurate to cooperate with an internal diameter of the cylindrical-housing subassembly, and a variable root diameter. In order to accomplish a two stage plasticizing operation, the variable root diameter basically increases from a minimum to a maximum along a first stage, starting from one extremity, proximate to a drive end to an end of this stage. Along a second stage the root diameter basically replicates the first stage by increasing from the minimum to the maximum diameter. The plasticizing assembly further comprises band-heaters, mounted around the cylindrical-housing subassembly, respectively its external surface; a hopper connected to a feed port of the cylindrical-housing subassembly, wherein synthetic resinous material is discharged; an inlet for introducing an inert gas into the cylindrical-housing subassembly communicating with the feed port; an exhaust vent devise connecting the interior of the cylindrical-housing subassembly with the environment; and an electrical motor-mechanical transmission unit being coupled to the two stage plasticizing screw.
In another aspect of the present invention, each of the injection assemblies comprises a stepped body that incorporates an injection cylinder, coaxial with an actuating cylinder.
The injection cylinder has a diameter relatively smaller than the diameter of the actuating cylinder, and is usually provided with heating elements. A plunger is located within the injection cylinder, while a piston is located in the actuating cylinder. A rod conveniently interconnects the plunger with the piston, and under the pressure of a fluid, the piston is displaced towards the injection cylinder.
In yet another aspect of this invention, the interconnecting assembly comprises a manifold, having, centrally, a two position - four port valve. The manifold is connected, at its middle, to:
a) the plasticization assembly and, at its extremities, to b) each one of the pair of injection assemblies; the two position - four port valve having - a first port connected to the cylindrical-housing subassembly;
- a second port connected to one of the pair of inj action cylinders;
- a third port connected to another one of the pair of injection cylinders;
and - a fourth port connected, via a nozzle, to a molding assembly, the manifold being heated by conventional heating elements.
The method for injection molding, using the above described machine, comprises - masticating and plasticizing a pre-established quantity of the synthetic resinous material, generally provided with hygroscopic properties, in the plasticization assembly;
- expelling the synthetic resinous material, already masticated and plasticated, from the plasticization assembly, into one of the pair of injection assemblies, while - forcibly expelling the synthetic resinous material, already masticated and plasticated, from the other one of the pair of injection assemblies into a molding assembly, whereby a) masticating and plasticizing a pre-established quantity of the synthetic resinous material; generally provided with hygroscopic properties, in the plasticization assembly;
b) expelling the synthetic resinous material, already masticated and plasticated, from the plasticization assembly, into one of the pair of injection assemblies, while c) forcibly expelling the synthetic resinous material, already masticated and plasticated, from the other one of the pair of injection assemblies into a molding assembly, whereby forgoing steps b and c are alternatively performed by each one of the pair of injection assemblies, so that the method for injection molding is continuous.
III. Brief description of the Drawings Although the characteristic features of the invention will be particularly pointed out in the claims, the invention itself and the manner in which it may be made and used may be better understood by referring to the following description and accompanying drawings.
Like reference numerals refer to like parts throughout the several views of the drawings in which:
Figure 1 is a perspective view of the injection molding machine according to the presentinvention;
Figure 2 is a vertical cross-section along the plasticization assembly;
Figure 3 is an enlarged view of Detail A of Fig. 2;
Figure 4 is a horizontal crass-section taken along the paasticization, injection and interconnecting assemblies; and Figure 5 is an enlarged view of Detail B of Fig. 4.
IV. Description of the Preferred Embodiment FIGS. 1 - 5 illustrate an injection molding machine 100 which incorporates the following main assemblies:
- a plasticization assembly 200 adapted to receive, masticate and plasticate a pre-established quantity of synthetic resinous material, plasticization assembly being flanked by - a pair of injection assemblies 300 communicating with plasticization assembly 200, so that while one of the pair of injection assemblies 300 communicates with plasticization assembly 200 to receive the synthetic resinous material, already masticated and plasticated, the other one of the pair of injection assemblies forcibly expels the synthetic resinous material, already masticated and plasticated, into a molding assembly (not shown);
- an interconnecting assembly 400 for providing - a communication between plasticization assembly 200 and each one of the pair of injection assemblies 300, alternatively, and - a communication between one of the pair of injection assemblies 300, which is not in communication with plasticization assembly 200, and the molding assembly;
- a common base 500 incorporating a lower stationary base 510 and an upper moving base 520, the latter being used - to support and - alternatively translate plasticization assembly 200 and the pair of injection assemblies 300 on lower stationary base 510; and - a translating assembly 600 for alternatively translating upper moving base with respect to lower stationary base 510 and a the molding assembly.
Referring now in detail, said plasticization assembly 200 comprises a cylindrical-housing subassembly 205 /constituted of several components/, wherein a two stage plasticizing screw 210 rotates about its longitudinal axis of symmetry, without rectilinear displacement. Thus, the pre-established quantity of synthetic resinous material is transformed and advanced. The two stage plasticizing screw 210 is constituted by a thread 215 having a constant external diameter 220, commensurate to cooperate with an internal diameter 225 of cylindrical-housing subassembly 205, and a variable root diameter 230. In order to accomplish a two stage plasticizing operation, the variable root diameter 230 basically increases from a minimum to a maximum along a first stage, starting from one extremity, proximate to a drive end to an end of this stage.
Along a second stage the root diameter 230 basically replicates the first stage by increasing from the minimum to the maximum diameter. Plasticizing assembly 200 further comprises: a) band-heaters 235, mounted around cylindrical-housing subassembly 205, respectively its external surface; b) a hopper 240, wherein synthetic resinous material is discharged; and c) a feed port 250 of cylindrical-housing subassembly 205. An inlet 255 for introducing an inert gas into cylindrical-housing subassembly 205 communicates with feed port 250.
An exhaust vent device 260 connects the interior of cylindrical-housing subassembly 205 with the environment. An electrical motor- mechanical transmission unit 265 is coupled to two stage plasticizing screw 210.
. 5 _.....___.____.m~.
Each of injection assemblies 300 comprises a stepped body subassembly 305 that incorporates an inj ection cylinder 310, coaxial with an actuating cylinder 315. Inj ection cylinder 310 has a diameter relatively smaller than the diameter of actuating cylinder 315 and is usually provided with heating elements 313. A plunger 320 is located within injection cylinder 310, while a piston 325 is located in actLrating cylinder 315. A rod 330 conveniently interconnects plunger 320 with piston 325. Under the pressure of a fluid, piston 325 is displaced towards injection cylinder 310.
Interconnecting assembly 400, comprising a manifold 405., wherein, centrally, a two position - four port valve 410 is incorporated. Manifold 405 is connected, at its middle, to:
a) plasticization assembly 200 and, at its extremities, to b) each one of the pair of injection assemblies 300.
Two position - four port valve 410 has - a first port 415 connectable to cylindrical-housing subassembly 205;
- a second port 420 connectable to one of the pair of injection cylinders 310;
- a third port 425 connectable to another one of the pair of injection cylinders 310;
and - a fourth port 430 connectable via a nozzle 435 to the molding assembly.
Manifold 405 is also generally heated by conventional external elements (not shown).
Two position - port valve 410 is operated as follows:
in a first position, first port 415 communicates with second port 420, so that the synthetic resinous material, already masticated and plasticated, is extruded from cylindrical housing 205 of plasticization assembly 200, into one of the pair of injection assemblies 300, via manifold 405; simultaneously, when third port 42S communicates with forth port 430, the synthetic resinous material is forcible expelled from one of the pair of injection assemblies 300 via manifold 405 and through nozzle 435 to the molding assembly;
in a second position, first port 415 communicates with third port 425, so that the synthetic resinous material, already masticated and plasticated, is extruded from cylindrical housing 205 of plasticization assembly 200, into another one of the pair of injection assemblies 300, via manifold 405; simultaneously, when second port communicates with forth port 430, the synthetic resinous material is forcible expelled from one of the pair of injection assemblies 300 via manifold 405 and through nozzle 435 to the molding assembly(not shown).
The method for injection molding, according to the present invention, is adapted for use with the foregoing injection molding machine.
The method for injection molding comprises - masticating and plasticizing a pre-established quantity of the synthetic resinous material, generally provided with hygroscopic properties, in the plasticization assembly 200, namely in cylindrical-housing subassembly 205;
- expelling the synthetic resinous material, already masticated and plasticated, from the cylindrical-housing subassembly 205, into one of the pair of injection assemblies 300, namely into one injection cylinder 310, while - forcibly expelling the synthetic resinous material, already masticated and plasticated, from the other one of the pair of injection cylinders 310 into the molding assembly, whereby a) masticating and plasticizing a pre-established quantity of the synthetic resinous material, generally provided with hygroscopic properties, in the cylindrical-housing subassembly 205;
b) expelling the synthetic resinous material, already masticated and plasticated, from the plasticization cylinder, into one of said pair of injection cylinders 310, while c) forcibly expelling the synthetic resinous material, already masticated and plasticated, from the other one of the pair of injection cylinders 310 into the molding assembly, whereby forgoing steps b and c are alternatively performed by each one of the pair of injection assemblies 300, so that the method for injection molding is continuous.
a) the plasticization assembly and, at its extremities, to b) each one of the pair of injection assemblies; the two position - four port valve having - a first port connected to the cylindrical-housing subassembly;
- a second port connected to one of the pair of inj action cylinders;
- a third port connected to another one of the pair of injection cylinders;
and - a fourth port connected, via a nozzle, to a molding assembly, the manifold being heated by conventional heating elements.
The method for injection molding, using the above described machine, comprises - masticating and plasticizing a pre-established quantity of the synthetic resinous material, generally provided with hygroscopic properties, in the plasticization assembly;
- expelling the synthetic resinous material, already masticated and plasticated, from the plasticization assembly, into one of the pair of injection assemblies, while - forcibly expelling the synthetic resinous material, already masticated and plasticated, from the other one of the pair of injection assemblies into a molding assembly, whereby a) masticating and plasticizing a pre-established quantity of the synthetic resinous material; generally provided with hygroscopic properties, in the plasticization assembly;
b) expelling the synthetic resinous material, already masticated and plasticated, from the plasticization assembly, into one of the pair of injection assemblies, while c) forcibly expelling the synthetic resinous material, already masticated and plasticated, from the other one of the pair of injection assemblies into a molding assembly, whereby forgoing steps b and c are alternatively performed by each one of the pair of injection assemblies, so that the method for injection molding is continuous.
III. Brief description of the Drawings Although the characteristic features of the invention will be particularly pointed out in the claims, the invention itself and the manner in which it may be made and used may be better understood by referring to the following description and accompanying drawings.
Like reference numerals refer to like parts throughout the several views of the drawings in which:
Figure 1 is a perspective view of the injection molding machine according to the presentinvention;
Figure 2 is a vertical cross-section along the plasticization assembly;
Figure 3 is an enlarged view of Detail A of Fig. 2;
Figure 4 is a horizontal crass-section taken along the paasticization, injection and interconnecting assemblies; and Figure 5 is an enlarged view of Detail B of Fig. 4.
IV. Description of the Preferred Embodiment FIGS. 1 - 5 illustrate an injection molding machine 100 which incorporates the following main assemblies:
- a plasticization assembly 200 adapted to receive, masticate and plasticate a pre-established quantity of synthetic resinous material, plasticization assembly being flanked by - a pair of injection assemblies 300 communicating with plasticization assembly 200, so that while one of the pair of injection assemblies 300 communicates with plasticization assembly 200 to receive the synthetic resinous material, already masticated and plasticated, the other one of the pair of injection assemblies forcibly expels the synthetic resinous material, already masticated and plasticated, into a molding assembly (not shown);
- an interconnecting assembly 400 for providing - a communication between plasticization assembly 200 and each one of the pair of injection assemblies 300, alternatively, and - a communication between one of the pair of injection assemblies 300, which is not in communication with plasticization assembly 200, and the molding assembly;
- a common base 500 incorporating a lower stationary base 510 and an upper moving base 520, the latter being used - to support and - alternatively translate plasticization assembly 200 and the pair of injection assemblies 300 on lower stationary base 510; and - a translating assembly 600 for alternatively translating upper moving base with respect to lower stationary base 510 and a the molding assembly.
Referring now in detail, said plasticization assembly 200 comprises a cylindrical-housing subassembly 205 /constituted of several components/, wherein a two stage plasticizing screw 210 rotates about its longitudinal axis of symmetry, without rectilinear displacement. Thus, the pre-established quantity of synthetic resinous material is transformed and advanced. The two stage plasticizing screw 210 is constituted by a thread 215 having a constant external diameter 220, commensurate to cooperate with an internal diameter 225 of cylindrical-housing subassembly 205, and a variable root diameter 230. In order to accomplish a two stage plasticizing operation, the variable root diameter 230 basically increases from a minimum to a maximum along a first stage, starting from one extremity, proximate to a drive end to an end of this stage.
Along a second stage the root diameter 230 basically replicates the first stage by increasing from the minimum to the maximum diameter. Plasticizing assembly 200 further comprises: a) band-heaters 235, mounted around cylindrical-housing subassembly 205, respectively its external surface; b) a hopper 240, wherein synthetic resinous material is discharged; and c) a feed port 250 of cylindrical-housing subassembly 205. An inlet 255 for introducing an inert gas into cylindrical-housing subassembly 205 communicates with feed port 250.
An exhaust vent device 260 connects the interior of cylindrical-housing subassembly 205 with the environment. An electrical motor- mechanical transmission unit 265 is coupled to two stage plasticizing screw 210.
. 5 _.....___.____.m~.
Each of injection assemblies 300 comprises a stepped body subassembly 305 that incorporates an inj ection cylinder 310, coaxial with an actuating cylinder 315. Inj ection cylinder 310 has a diameter relatively smaller than the diameter of actuating cylinder 315 and is usually provided with heating elements 313. A plunger 320 is located within injection cylinder 310, while a piston 325 is located in actLrating cylinder 315. A rod 330 conveniently interconnects plunger 320 with piston 325. Under the pressure of a fluid, piston 325 is displaced towards injection cylinder 310.
Interconnecting assembly 400, comprising a manifold 405., wherein, centrally, a two position - four port valve 410 is incorporated. Manifold 405 is connected, at its middle, to:
a) plasticization assembly 200 and, at its extremities, to b) each one of the pair of injection assemblies 300.
Two position - four port valve 410 has - a first port 415 connectable to cylindrical-housing subassembly 205;
- a second port 420 connectable to one of the pair of injection cylinders 310;
- a third port 425 connectable to another one of the pair of injection cylinders 310;
and - a fourth port 430 connectable via a nozzle 435 to the molding assembly.
Manifold 405 is also generally heated by conventional external elements (not shown).
Two position - port valve 410 is operated as follows:
in a first position, first port 415 communicates with second port 420, so that the synthetic resinous material, already masticated and plasticated, is extruded from cylindrical housing 205 of plasticization assembly 200, into one of the pair of injection assemblies 300, via manifold 405; simultaneously, when third port 42S communicates with forth port 430, the synthetic resinous material is forcible expelled from one of the pair of injection assemblies 300 via manifold 405 and through nozzle 435 to the molding assembly;
in a second position, first port 415 communicates with third port 425, so that the synthetic resinous material, already masticated and plasticated, is extruded from cylindrical housing 205 of plasticization assembly 200, into another one of the pair of injection assemblies 300, via manifold 405; simultaneously, when second port communicates with forth port 430, the synthetic resinous material is forcible expelled from one of the pair of injection assemblies 300 via manifold 405 and through nozzle 435 to the molding assembly(not shown).
The method for injection molding, according to the present invention, is adapted for use with the foregoing injection molding machine.
The method for injection molding comprises - masticating and plasticizing a pre-established quantity of the synthetic resinous material, generally provided with hygroscopic properties, in the plasticization assembly 200, namely in cylindrical-housing subassembly 205;
- expelling the synthetic resinous material, already masticated and plasticated, from the cylindrical-housing subassembly 205, into one of the pair of injection assemblies 300, namely into one injection cylinder 310, while - forcibly expelling the synthetic resinous material, already masticated and plasticated, from the other one of the pair of injection cylinders 310 into the molding assembly, whereby a) masticating and plasticizing a pre-established quantity of the synthetic resinous material, generally provided with hygroscopic properties, in the cylindrical-housing subassembly 205;
b) expelling the synthetic resinous material, already masticated and plasticated, from the plasticization cylinder, into one of said pair of injection cylinders 310, while c) forcibly expelling the synthetic resinous material, already masticated and plasticated, from the other one of the pair of injection cylinders 310 into the molding assembly, whereby forgoing steps b and c are alternatively performed by each one of the pair of injection assemblies 300, so that the method for injection molding is continuous.
Claims (5)
1. An injection molding machine which incorporates the following main assemblies:
- a plasticization assembly adapted to receive, masticate and plasticize a pre-established quantity of synthetic resinous material, said plasticization assembly being flanked by - a pair of injection assemblies communicating with said plasticization assembly, so that while one of said pair of injection assemblies communicates with said plasticization assembly to receive said synthetic resinous material, already masticated and plasticated, the other one of said pair of injection assemblies forcibly expels said synthetic resinous material, already masticated and plasticated, into a molding assembly;
- an interconnecting assembly for providing a communication between said plasticization assembly and each one of said pair of injection assemblies, alternatively, and - a communication between one of said pair of injection assemblies, which is not in communication with said plasticization assembly, and said molding assembly;
- a common base incorporating a lower stationary base and an upper moving base, the latter being used - to support and - alternatively translate said plasticization assembly and said pair of injection assemblies on said lower stationary base; and - a translating assembly for alternatively translating said upper moving base with respect to said lower stationary base and said molding assembly.
- a plasticization assembly adapted to receive, masticate and plasticize a pre-established quantity of synthetic resinous material, said plasticization assembly being flanked by - a pair of injection assemblies communicating with said plasticization assembly, so that while one of said pair of injection assemblies communicates with said plasticization assembly to receive said synthetic resinous material, already masticated and plasticated, the other one of said pair of injection assemblies forcibly expels said synthetic resinous material, already masticated and plasticated, into a molding assembly;
- an interconnecting assembly for providing a communication between said plasticization assembly and each one of said pair of injection assemblies, alternatively, and - a communication between one of said pair of injection assemblies, which is not in communication with said plasticization assembly, and said molding assembly;
- a common base incorporating a lower stationary base and an upper moving base, the latter being used - to support and - alternatively translate said plasticization assembly and said pair of injection assemblies on said lower stationary base; and - a translating assembly for alternatively translating said upper moving base with respect to said lower stationary base and said molding assembly.
2. The injection molding machine, as defined in claim 1, wherein said plasticization assembly comprises a cylindrical-housing subassembly incorporating a two stage plasticizing screw that rotates about its longitudinal axis of symmetry, without rectilinear displacement, thus, said pre-established quantity of synthetic resinous material is transformed and advanced, said two stage plasticizing screw being constituted by a thread having a constant external diameter, commensurate to cooperate with an internal diameter of said cylindrical-housing subassembly, and a variable root diameter, and in order to accomplish a two stage plasticizing operation, said variable root diameter basically increases from a minimum to a maximum along a first stage, starting from one extremity, proximate to a drive end to an end of this stage, along a second stage said root diameter basically replicates said first stage by increasing from said minimum to said maximum diameter; said plasticizing assembly further comprising band-heaters, mounted around said cylindrical-housing subassembly, respectively its external surface, a hopper, wherein synthetic resinous material is discharged, connected to a feed port of said cylindrical-housing subassembly, an inlet for introducing an inert gas into said cylindrical-housing subassembly communicating with said feed port; an exhaust vent device connecting the interior of said cylindrical-housing subassembly with the environment, an electrical motor- mechanical transmission unit being coupled to said two stage plasticizing screw.
3. The injection molding machine, as defined in claim 1 or 2, wherein each of said injection assemblies comprises a stepped body that incorporates an injection cylinder, coaxial with an actuating cylinder, said injection cylinder having a diameter relatively smaller than the diameter of said actuating cylinder and being provided by heating elements; a plunger being located within said injection cylinder, while a piston is located in said actuating cylinder; a rod conveniently interconnecting said plunger with said piston; and under the pressure of a fluid, said piston is displaced towards said injection cylinder.
4. The injection molding machine, as defined in claim 3, wherein said interconnecting assembly, comprises a manifold, having, centrally, a two position - four port valve, said manifold being connected, at its middle, to:
a) said plasticization assembly and, at its extremities, to b) each one of said pair of injection assemblies; said two position - four port valve having - a first port connected to said cylindrical-housing subassembly;
- a second port connected to one of said pair of injection cylinders;
- a third port connected to another one of said pair of injection cylinders;
and - a fourth port connected, via a nozzle, to a molding assembly; said manifold being heated by conventional heating elements.
a) said plasticization assembly and, at its extremities, to b) each one of said pair of injection assemblies; said two position - four port valve having - a first port connected to said cylindrical-housing subassembly;
- a second port connected to one of said pair of injection cylinders;
- a third port connected to another one of said pair of injection cylinders;
and - a fourth port connected, via a nozzle, to a molding assembly; said manifold being heated by conventional heating elements.
5. A method for injection molding, adapted for use with an injection molding machine, said injection molding machine incorporating the following main assemblies:
- a plasticization assembly, used for receiving, masticating and plasticization of a pre-established quantity of synthetic resinous material, and flanked by - a pair of injection assemblies communicating with said plasticization assembly, so that while one of said pair of injection assemblies communicates with said plasticization assembly to receive said synthetic resinous material, already masticated and plasticated, the other one of said pair of injection assemblies forcibly expels said synthetic resinous material, already masticated and plasticated, into a molding assembly;
- an interconnecting assembly for providing a communication between said plasticization assembly and each one of said pair of injection assemblies, alternatively, and - a communication between one of said pair of injection assemblies, which is not in communication with said plasticization assembly, and said molding assembly;
- a common base incorporating a lower stationary base and an upper moving base, the latter being used - to support and - translate said plasticization assembly and said pair of injection assemblies along said lower stationary base; and - a translating assembly for displacing said upper moving base with respect to said lower stationary base, to contact said molding assembly or retract therefrom, - said method for injection molding comprising a) masticating and plasticization of a pre-established quantity of said synthetic resinous material, generally provided with hygroscopic properties, in said plasticization assembly;
b) expelling said synthetic resinous material, already masticated and plasticated, from said plasticization assembly, into one of said pair of injection assemblies, while c) forcibly expelling said synthetic resinous material, already masticated and plasticated, from the other of said pair of injection assemblies into said molding assembly, whereby forgoing steps b and c are alternatively performed by each one of said pair of injection assemblies, so that said method for injection molding is continuous.
- a plasticization assembly, used for receiving, masticating and plasticization of a pre-established quantity of synthetic resinous material, and flanked by - a pair of injection assemblies communicating with said plasticization assembly, so that while one of said pair of injection assemblies communicates with said plasticization assembly to receive said synthetic resinous material, already masticated and plasticated, the other one of said pair of injection assemblies forcibly expels said synthetic resinous material, already masticated and plasticated, into a molding assembly;
- an interconnecting assembly for providing a communication between said plasticization assembly and each one of said pair of injection assemblies, alternatively, and - a communication between one of said pair of injection assemblies, which is not in communication with said plasticization assembly, and said molding assembly;
- a common base incorporating a lower stationary base and an upper moving base, the latter being used - to support and - translate said plasticization assembly and said pair of injection assemblies along said lower stationary base; and - a translating assembly for displacing said upper moving base with respect to said lower stationary base, to contact said molding assembly or retract therefrom, - said method for injection molding comprising a) masticating and plasticization of a pre-established quantity of said synthetic resinous material, generally provided with hygroscopic properties, in said plasticization assembly;
b) expelling said synthetic resinous material, already masticated and plasticated, from said plasticization assembly, into one of said pair of injection assemblies, while c) forcibly expelling said synthetic resinous material, already masticated and plasticated, from the other of said pair of injection assemblies into said molding assembly, whereby forgoing steps b and c are alternatively performed by each one of said pair of injection assemblies, so that said method for injection molding is continuous.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2476712 CA2476712A1 (en) | 2004-08-17 | 2004-08-17 | Method for injection molding and injection molding machine therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2476712 CA2476712A1 (en) | 2004-08-17 | 2004-08-17 | Method for injection molding and injection molding machine therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2476712A1 true CA2476712A1 (en) | 2004-11-17 |
Family
ID=33438085
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2476712 Abandoned CA2476712A1 (en) | 2004-08-17 | 2004-08-17 | Method for injection molding and injection molding machine therefor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2476712A1 (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102700090A (en) * | 2012-06-20 | 2012-10-03 | 无锡天惠塑机有限公司 | Injection component for injection molding machine |
| CN103821794A (en) * | 2014-03-06 | 2014-05-28 | 宁波欧意莱机械制造有限公司 | Return driving mechanism of injection molding machine oil cylinder |
| WO2017145680A1 (en) * | 2016-02-22 | 2017-08-31 | 株式会社 日本製鋼所 | Injection device provided with flow path switching block |
| JP2017148952A (en) * | 2016-02-22 | 2017-08-31 | 株式会社日本製鋼所 | Plunger type injection device having valve block provided at top of device |
| JP2017148956A (en) * | 2016-02-22 | 2017-08-31 | 株式会社日本製鋼所 | Flow pass changeover device of plasticization injection device |
| CN107511964A (en) * | 2017-10-23 | 2017-12-26 | 广东亚泰科技有限公司 | A kind of BMC injection machines |
| JP2018065271A (en) * | 2016-10-18 | 2018-04-26 | 株式会社日本製鋼所 | Operation method of plasticization injection device and plasticization injection device |
| JP2018158503A (en) * | 2017-03-23 | 2018-10-11 | 株式会社日本製鋼所 | Operation method of injection device comprising plasticizing device and plunger type injection device |
-
2004
- 2004-08-17 CA CA 2476712 patent/CA2476712A1/en not_active Abandoned
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102700090A (en) * | 2012-06-20 | 2012-10-03 | 无锡天惠塑机有限公司 | Injection component for injection molding machine |
| CN103821794A (en) * | 2014-03-06 | 2014-05-28 | 宁波欧意莱机械制造有限公司 | Return driving mechanism of injection molding machine oil cylinder |
| CN103821794B (en) * | 2014-03-06 | 2016-06-01 | 宁波欧意莱机械制造有限公司 | Driving mechanism return by a kind of injection moulding machine oil cylinder |
| WO2017145680A1 (en) * | 2016-02-22 | 2017-08-31 | 株式会社 日本製鋼所 | Injection device provided with flow path switching block |
| JP2017148952A (en) * | 2016-02-22 | 2017-08-31 | 株式会社日本製鋼所 | Plunger type injection device having valve block provided at top of device |
| JP2017148956A (en) * | 2016-02-22 | 2017-08-31 | 株式会社日本製鋼所 | Flow pass changeover device of plasticization injection device |
| EP3421217A4 (en) * | 2016-02-22 | 2019-11-06 | The Japan Steel Works, Ltd. | Injection device provided with flow path switching block |
| US10850438B2 (en) | 2016-02-22 | 2020-12-01 | The Japan Steel Works, Ltd. | Injection device provided with flow path switching block |
| JP2018065271A (en) * | 2016-10-18 | 2018-04-26 | 株式会社日本製鋼所 | Operation method of plasticization injection device and plasticization injection device |
| JP2018158503A (en) * | 2017-03-23 | 2018-10-11 | 株式会社日本製鋼所 | Operation method of injection device comprising plasticizing device and plunger type injection device |
| CN107511964A (en) * | 2017-10-23 | 2017-12-26 | 广东亚泰科技有限公司 | A kind of BMC injection machines |
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