• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A screw (3) for an injection molding machine (1) forms in a heating cylinder (2) a first compression section (6) for compressing a resin, a decompression section (9) for lowering a pressure of a resin and an inert gas introduced therein; and a second compressing section (10) for compressing the resin from its rear side to its front side. The worm (3) has between the first compressing section (6) and the decompressing section (9) a predetermined sealing structure (7) for preventing reverse flow of the resin and a decompressing relaxation section (5) disposed on a downstream side of the sealing structure (7) is and has a predetermined shape of a thread. In the decompression releasing section (5), at least two shallow groove portions (13) having a shallow worm groove are formed between the worm threads in the axial direction.
    公开号:AT519150A2
    申请号:T396/2017
    申请日:2017-10-05
    公开日:2018-04-15
    发明作者:Uezono Hiromasa；Tamada Koichi
    申请人:Japan Steel Works Ltd；
    IPC主号:
    专利说明:

    A molded product, that is, a molded foam product in which a large number of small air bubbles are contained, is not only light in weight but also excellent in strength, and a corresponding field of application is wide. In order to obtain a molded foam product by injection molding, it is necessary to mix a foam-forming agent with a resin, and the foam-forming agent comprises a chemical foam-forming agent and a physical foam-forming agent. As the chemical foam-forming agent, a chemical foam-forming agent is known which is decomposed by heat so that a gas is generated, for example, azodicarboxylic acid amide is known for this. The chemical foaming agent is mixed into a resin pellet of a material and placed in a heating cylinder so that it is mixed into the molten resin. When the molten resin is injected into a mold, the chemical foaming agent foams, so that a molded foam product is obtained. On the other hand, the physical foam-forming agent contains an inert gas such as nitrogen and carbon dioxide. The inert gas is injected into the molten resin in the heating cylinder under a predetermined pressure so that the inert gas is in a state that it is saturated in the resin. If the melted resin in
    2/30 • · · · · ···· ···· · · · · • · · ·· • · ·· · · · • · · ·· • · · ·· ··· ·· ·· · · »·· When a mold is injected, the pressure in the resin decreases and the inert gas causes bubbles to form. When the resin has cooled and solidified, a molded foam product is formed. A physical foam-forming agent containing an inert gas has a high penetration force because the physical foam-forming agent is introduced into the resin under high pressure and at a high temperature, and there is a high possibility that it is compared to the chemical foam-forming agent is evenly distributed in the resin. There is therefore the excellent property that uneven foam formation in the molded foam product obtained is very unlikely to occur.
    JP-A-2002-79545 describes a molding process for obtaining a molded foam product using a physical foam-forming agent containing an inert gas. An injection molding machine 50 used for the method for molding the molded foam product will be described with reference to FIG. 3. The injection molding system 50 comprises a heating cylinder 51 and a screw 52, which is provided in the heating cylinder 51 in such a way that it can be driven in one direction of rotation and one axial direction. In the screw 52, two compression areas with shallow screw grooves, i.e., a first and a second compression area 54 and 56, are formed, and a recessed area 55 with a deep screw groove is between the first and the second second compression area 54 and 56 formed. An inert gas introduction area 57 is provided in the heating cylinder 51 so that it corresponds to the recessed area 55, so that the inert gas 58 is introduced. In the injection molding machine 50, the resin pellet is introduced from a hopper 59, and the screw 52 is rotated. The resin pellet is then melted and moved to the front of the screw 52
    3.30
    I
    • «• · · ·· ·· · · · ·· ·· ··· ·· ·· • · funded. When the molten resin is conveyed to the front, the molten resin is compressed in the first compression area and its pressure is reduced in the recessed area 55. An inert gas 58 is introduced into the recessed area. Thereafter, the inert gas 58 is mixed with the molten resin and reaches a saturated state. Such a molten resin is compressed again in the second compression region 56 and is metered in at the front end of the screw 52. When the molten resin is injected into a mold, the inert gas in the resin evaporates to give a molded foam product.
    When electroless plating is carried out on a molded foam product and when the molded product is obtained by injecting molten resin to which a surface modifying material such as a metal complex is added, a necessary pretreatment becomes unnecessary. JP-A-2015-168079 describes an injection molding machine 60 which can inject the surface modifying material such as the metal complex into molten resin, and which can knead and inject the surface modifying material and the molten resin. As shown in FIG. 4, the injection molding system 60 is formed by a heating cylinder 61 and a screw 62. A first and a second sealing structure 64 and 65 are provided in the screw 62 at predetermined positions. A high-pressure region 66 and a low-pressure region 67 are formed in the screw 62 by the first and the second sealing structure 64 and 65. The first sealing structure 64 has a predetermined valve structure such that the resin conveyed from a rear side to the front side of the screw 62 is conveyed to the high pressure region 66, but reverse flow from the high pressure region 66 to its rear side is prevented. The second sealing structure 65 has a valve structure which corresponds to a direction of rotation of the
    4/30
    Snail 62 is opened and closed. When the valve structure of the second sealing structure 65 is closed, the high pressure region 66 and the low pressure region 67 are blocked and the resin cannot flow, but when the sealing structure is opened, the resin can flow freely. The worm 62 is provided with a decompression relaxation section 68 on a downstream side of the second sealing structure 65 in the low pressure region 67. In the decompression relaxation section 68, a deep groove portion 69 with a deep worm groove and a shallow groove portion 70 with a shallow worm groove are alternately formed between worm threads, and at least two shallow groove portions 70 and 70 are formed in the axial direction , When the resin flows from the high pressure region 66 to the low pressure region 67 by the displacement effect exerted in the shallow groove regions 70 and 70, the pressure is appropriately reduced. The heating cylinder 61 is provided with an injection port 72 for introducing inert gas or the like associated with the high pressure area 66 and an outlet port 73 for discharging the inert gas on the downstream side of the decompression relaxation section 68 into the low pressure area 67. A process for obtaining a molded product by injecting a molten resin to which a surface modifying material such as a metal complex is added is as follows. The screw 62 is rotated to melt the resin. The molten resin flows through the first sealing structure 64 and is conveyed to the high pressure region 66. The worm 62 is rotated in the opposite direction to close the second sealing structure 65. The high-pressure region 66 is then in a state in which it is completely closed, this being achieved by the first and the second sealing structures 64 and 65.
    / 30
    A surface modifying material, such as a metal complex, is injected from the injection port 72 together with the high pressure inert gas 74. In the high pressure region 66, the surface modifying material is distributed in the molten resin. When the screw 62 is rotated in the forward direction, the second sealing structure 65 opens and the molten resin flows through the high pressure area 66 to the low pressure area 67, but the pressure is gradually reduced due to the decompression relaxation section 68. Inert gas exits the molten resin, and the inert gas is discharged from the outlet port 73. When a molten resin to which a surface modifying material is added is injected into a mold, a desired molded product is obtained.
    The injection molding system 60 with the screw 62, which in
    JP-A-2015-168079 can also be used for a method for molding a molded foam product using a physical foam-forming agent, that is, using an inert gas. In particular, only the high-pressure inert gas is introduced into the high-pressure region 66 without injecting the surface-modifying material. The inert gas is introduced, for example, at 10 MPa. The inert gas is sufficiently dispersed and penetrates sufficiently into the molten resin within the high pressure region 66, and then the molten resin is conveyed into the low pressure region 67. In the low pressure region 67, the valve provided in the outlet port 73 is controlled so that the pressure inside the heating cylinder 61 is set to about 5 MPa. Then, excess inert gas is generated from the molten resin in the low pressure region 67 and is discharged from the outlet port 73 while, on the other hand, obtaining molten resin in which the
    6.30
    inert gas is dissolved in a saturated state. When the molten resin is injected into a mold, the inert gas creates air bubbles in the resin and a molded foam product is obtained.
    The injection molding machines 50 and 60 described in JP-A-2002-79545 and JP-A-2015-168079 can produce molded foam products by appropriately introducing an inert gas into the molten resin, but there are problems to be solved in each machine. First, with respect to the injection molding machine 50 described in JP-A-2002-79545, there is a problem that the inert gas is discharged from the hopper 59 or that the molten resin is pushed back by the inert gas when the inert gas is in Reverse flows. As soon as the screw 52 is rotated in the forward direction to convey the resin to the front, there is concern that the inert gas introduced in the recessed area 55 will flow in the reverse direction. / In other words, when the screw 52 rotates in the forward direction, there is a sufficient pressure difference between the first compression region 54 and the recessed region 55, the inert gas does not flow in the backward direction, but is kneaded into the molten resin, which becomes the molten resin conveyed to the front and is metered by means of the second compression area 56. However, when the rotation of the screw 52 stops, the pressure difference in the heating cylinder 51 decreases. At this time, since the inert gas under high pressure has a high penetration force, the inert gas flows in the reverse direction beyond the first compression region 54. There is a risk that the molten resin will be pushed back by the inert gas flowing in the reverse direction and the funnel 59 will increase in volume. Since the rotation of the screw 52 is stopped at least during the injection, it is difficult to flow in the backward direction of the / 30
    to completely prevent inert gas, and there is a problem that the molding cycle cannot be carried out stably. Next, when considering the injection molding machine 60 described in JP-A-2015-168079, the inert gas does not flow in the reverse direction because the first sealing structure 64 is provided in the injection molding machine 60 even if the rotation of the Screw 62 is interrupted and the pressure difference in the heating cylinder 61 decreases. Therefore, a molded foam product can be molded in a stable manner. However, in the injection molding system described in JP-A-2015-168079, the high-pressure region 66 in the screw 62, which is divided by the first and the second sealing structure 64 and 65, is absolutely necessary. The length of the system of the injection molding system 60 therefore becomes greater due to the high-pressure region 66. In order to build the injection molding system 60 in a limited installation area, there is therefore a need to make the length of the system smaller.
    OVERVIEW
    Illustrative aspects of the present invention provide a screw for an injection molding machine and an injection molding machine, and in particular, a screw for an injection molding machine and an injection molding machine are provided in which a molded foam product by injecting a physical foam-forming agent containing an inert gas into molten resin is molded, and there is no fear that the inert gas flows in the heating cylinder in the reverse direction and therefore a molded foam product cannot be molded stably, and a length of the unit is sufficiently short so that the injection molding unit can be set up even in a limited installation area.
    8/30 • · · «· • * · · · · ·„ _ ···· * · ·.
    • · · · · · · · ·· ·
    In order to achieve the object of the present invention, the present invention is designed to aim at a screw for an injection molding machine in which a first compression section in which a resin is compressed, a decompression section in which a pressure of a resin is lowered , and a second compression section, in which a resin is compressed, are formed in a heating cylinder from a back to a front thereof, and wherein inert gas is introduced into the decompression section. The screw is provided with a predetermined sealing structure that prevents resin from flowing backward, and a decompression relief portion that has a predetermined shape of a screw thread on a downstream side of the sealing structure between the first compression portion and the decompression portion. In the decompression relaxation section, at least two flat groove regions or flat groove regions are formed with a flat worm groove between the worm threads in the axial direction.
    According to a first illustrative aspect of the present invention, there is provided a screw for an injection molding system, which is configured in a heating cylinder, a first compression section for compressing a resin, a decompression section for reducing a pressure of the resin and a second compression section for compressing the resin starting from one Form back to a front, wherein the first compression section, the decompression section and the second compression section are formed according to the shape of the screw, and wherein an inert gas is introduced into the decompression section, wherein the screw has: a predetermined sealing structure for preventing a reverse flow of the resin; and a decompression relaxation section disposed on a downstream side of the sealing structure, and one
    9/30 • · • · · • · · • · · · · • · · · · (.......
    has a predetermined shape of a worm thread, wherein the sealing structure and the decompression-relaxation section are arranged between the first compression section and the decompression section, and wherein in the decompression-relaxation section at least two flat groove regions are formed with a flat screw groove between the screw threads in the axial direction.
    According to a second illustrative aspect of the present invention, in the screw for an injection molding system according to the first illustrative aspect, the decompression-relief section is formed by a multi-start thread consisting of at least two worm threads.
    According to a third illustrative aspect of the present invention, in the screw for an injection molding system according to the first or the second illustrative aspect, the sealing structure comprises: a seal which is designed to subdivide the first compression section and the decompression relaxation section in a liquid-tight manner; a connection passage that allows the first compression section and the decompression relaxation section to communicate with each other; and a valve mechanism configured to: close the communication passage; and cause molten resin in the first compression section to flow into the decompression relaxation section when the molten resin in the first compression section exceeds a predetermined pressure.
    According to a fourth illustrative aspect of the present invention, in the screw for an injection molding system according to the first or the second illustrative aspect, the sealing structure has: a region with a reduced diameter in which the diameter of the screw decreases; and one
    10/30 • · * ·
    Sealing ring which is fitted into the area with a reduced diameter with a predetermined gap therebetween and which is displaceable with respect to a bore of the heating cylinder in a liquid-tight manner, the area with reduced diameter having a tapered or conical surface, the sealing ring, when it lies on the conical surface, the connection between the first compression section and the decompression relaxation section is blocked.
    According to a fifth illustrative aspect of the present invention, there is provided an injection molding system comprising: the screw according to the first to fourth illustrative aspects, the heating cylinder having an injection port for introducing an inert gas into a predetermined position corresponding to the decompression section.
    According to the foregoing, the present invention is suitable as a screw for an injection molding machine in which a first compression section in which resin is compressed, a decompression section in which a pressure of a resin is lowered, and a second compression section in which a Resin is compressed, formed in a heating cylinder from the back to a front according to the shape of the screw, and an inert gas is introduced into the decompression section. The screw is provided with a predetermined sealing structure that prevents a backward flow of a resin, and a decompression relaxation section having a predetermined shape of a screw flight on a downstream side of the sealing structure between the first compression section and the decompression section, and in the decompression relaxation section at least two flat groove areas with a flat worm groove between the / 30
    Worm threads are formed in the axial direction. This screw is a screw that is provided in an injection molding plant to produce a molded foam product, and since in this way the screw can only have the first and second compression section, the decompression section, the sealing structure and the decompression relaxation section for the foam molding the length of the screw can be significantly reduced. Therefore, the length of the injection molding system can be reduced, and the injection molding system can be built in a limited installation volume. Since the decompression relaxation section is provided in the present invention, there is an effect that the inert gas can be introduced in a stable manner. The reason is that when the high-pressure resin compressed in the first compression section is conveyed to the decompression section via the decompression relaxation section, the pressure in at least two flat groove areas provided in the decompression relaxation section drops due to displacement. Since the resin under high pressure gradually loses pressure and flows to the decompression section, the inert gas can be introduced in a stable manner. Therefore, if the rotation of the screw is interrupted during insertion or the like, the pressure difference of the resin in the heating cylinder becomes small and the high pressure inert gas with the high penetration force is likely to flow in the reverse direction. However, in the scroll of the present invention, since the sealing structure and the decompression relief section are provided on the upstream side of the decompression section in which the inert gas is inserted, it is possible to reliably prevent the backward flow. In the decompression relaxation section there are at least two flat groove areas,
    12/30 which have a compressing action in the axial direction, and thus even if the molten resin tries to flow in the backward direction together with the inert gas, the flow in the backward direction is prevented, and the flow in the backward direction in the sealing structure is substantially completely suppressed in this. Therefore, the inert gas does not enter the first compression section, the inert gas is not discharged from the hopper, and the molten resin pushed back by the inert gas does not flow backward into the hopper. The screw injection molding machine according to the present invention can stably produce a molded foam product.
    BRIEF DESCRIPTION OF DRAWINGS
    1 is a side sectional view showing an injection molding machine according to the present embodiment, which is provided with a screw according to an embodiment of the present invention;
    2 are views showing a sealing structure provided in the screw according to the embodiment of the present invention, and FIG. 2 (a) and FIG. 2 (b) are sectional views showing a state in which sealing structures according to different embodiments are shown in section, which is parallel to a screw axis;
    Fig. 3 is a sectional side view showing a prior art injection molding machine; and
    Fig. 4 is a sectional side view showing another prior art injection molding machine.
    / 30
    • · • · 4 4 4 4 • 4 4 4 MM 4 4 4 4 4 • • 4 • 4 4 4 •• ♦ 4 44 4 4 φ • · • 4 • 4 • 4 • · 4 4 4 4 4 • 4 4 4 • · • 4 44 4 • 4 4 4 4 4
    DETAILED DESCRIPTION
    Embodiments of the present invention are described below. As shown in FIG. 1, an injection molding system according to an embodiment of the present invention has, among other things, a heating cylinder 2 and a screw 3, which is provided so that it is in a direction of rotation and in an axial direction in the heating cylinder 2 as in the injection molding system of the prior art is drivable. A plurality of band heating elements are wound around an outer peripheral surface of the heating cylinder 2, the plurality of band heating elements not being shown in the drawings.
    In the injection molding system 1 according to the present embodiment, a plurality of sections are formed in the heating cylinder 2 in accordance with a shape of the screw 3. In the present
    Embodiment generally includes a single thread pitch and a guide except for the decompression relaxation section 5 described below. In the vicinity of the hopper (not shown), although the screw 3 has a relatively deep screw groove between the screw flights, resin is melted and this is then conveyed to the front, whereby the screw 3 has a flat screw groove from a certain position up to a sealing structure 7, which is described below, and thus has a first compression section 6, in which a resin is compressed. A decompression relaxation section 5, which is adjacent to the sealing structure 7, is formed on the front side of the sealing structure 7, that is, on the downstream side thereof, and a decompression section 9 with a deep screw groove is formed on the downstream side thereof. Since the screw groove or screw groove is deep and the volume in the heating cylinder 2 is large, in the / 30 • ·· • ·· ♦ * · • ··
    • <· · · <9 · · • · · ·· · «9 9
    Decompression section 9 the pressure of the resin conveyed to the front. Therefore, as described below, in section 9 a physical foam-forming agent containing the inert gas is introduced as shown below. In the screw, a second compression section 10 is formed on the front side of the decompression section 9, that is, on its downstream side, in which the screw groove is flat and resin is compressed there. In the present embodiment, the depth of the screw groove changes in the shape of the screw, so that the first and second compression sections 6 and 10 and the decompression section 9 are formed. However, the same sections 6, 9 and 10 can also be formed by changing other shapes of the worm threads, such as thread pitch, thread width or the like, of the shape of the worm.
    The decompression relaxation section S, which is a characteristic structure in the screw 3 according to the present embodiment, will now be described. In the present embodiment, the worm or thread of the decompression relaxation section 5 is formed by a two-start thread. Since the worm gear of the decompression relaxation section 5 is constructed by the two-start thread as described above, the molten resin fed to the decompression relaxation section 5 is continuously conveyed downstream without disturbing the flow or reverse flow even if the viscosity is low. The number of threads of the worm threads of the worm thread is not restricted, and a multi-start worm thread can be used. In such a decompression relaxation section 5 there are at least two deep groove areas 12 and 12 with a deep thread groove and at least two
    15/30. ·· · * ···· ···· ···· ···· • · · · · · a · • · · · · »· ·. ,
    ♦ * · · · · · · ··. · · ». · ... ·· .. · · .. · ·“ ·
    Flat groove areas 13 and 13 are formed with a flat thread groove in the axial direction. In other words, at least two flat groove areas 13 and 13 are formed. The flat groove areas 13 and 13 exert a displacement effect. Therefore, in the decompression relaxation section 5, it is possible to gradually lower the pressure of the molten resin when the molten resin is conveyed to the front, and it is possible to prevent the molten resin containing the inert gas from being reversed. Direction flows when the rotation of the screw 3 is stopped.
    As shown in detail in Fig. 2 (a), the
    Sealing structure 7, which is provided in the screw 3 according to the present embodiment, a seal 15 and a flow control mechanism 16, which performs a pressure regulating function. The seal 15 is slidably fitted in a predetermined groove formed on an outer peripheral surface of the screw 3. Although the heating cylinder 2 is not shown in FIG. 2 (a), an outer peripheral surface of the seal 15 slides smoothly and in contact with the bore of the heating cylinder 2. The molten resin is prevented from flowing in the seal 15 and the inside of the The heating cylinder 2 is liquid-tightly divided into the first compression section 10 on an upstream side and the decompression relaxation section 5 on a downstream side thereof. One or more flow control mechanisms 16 are provided in the sealing structure 7. The flow control mechanism 16 is constructed by a communication passage 18 formed in the screw 3 so as to allow the first compression section 6 and the decompression relaxation section 5 to communicate with each other, and is constructed from a valve mechanism 19 which opens and closes the communication passage 18. A central area of the connection passage / 30 «· ·· ·············· * · • · · · · · · 9 • · · 9 ··· · ·»
    9 9 9 · · · 9 decreases in diameter in a conical shape so that a conical or tapered sealing surface 20 is formed. When a head region 23 of a cone valve 22, which forms the valve mechanism, rests on the sealing surface 20, the connecting passage 18 is closed. The plug valve 22 is formed by an umbrella-shaped head region 23 and a stem region 24, and a plurality of disc springs 26, 26 ... are provided on the stem region 24. The cone valve 22, which is provided with the plate springs 26, 26 ..., is inserted into a receptacle 27 which is open as a bore with a bottom. The receptacle 27 is screwed and fastened to a screw thread which is formed on an inner circumferential surface of the connecting passage 18, this being done by means of a male screw which is formed on an outer circumferential surface of the receptacle 27. Therefore, the cone valve 22 is biased by the plate springs 26, 26 ... so that the head region 23 is pressed against the sealing surface 20 and closes the connecting passage 18. When the molten resin in the first compression section 6 reaches a predetermined pressure, the poppet valve 22 moves in the reverse direction against the biasing force of the plate springs 26, 26 ... and the first compression section 6 and the decompression relaxation section 5 allow them to communicate with each other occur, and the molten resin flows into the decompression relaxation section 5. A resin passage is formed in the receptacle 27, and when the first compression section 6 and the decompression relaxation section 5 are connected, the molten resin flows out of the resin passage 28 into the Decompression-relief section 5. When the pressures in the first compression section 6 and the decompression-relaxation section 5 are equal to one another or when the pressure in the decompression-relaxation section 5 is higher, because the plug valve 22 rests on the sealing surface 20/30
    B and the connection therebetween is blocked, backward flow of the molten resin from the decompression relaxation section 5 into the first compression section 6 is completely prevented.
    In the injection molding machine 1 according to the present embodiment, as shown in FIG. 1, an inert gas inlet port 29 is provided at a position corresponding to the decompression relaxation section 5 in the heating cylinder 2. A line from a gas cylinder 31 containing an inert gas is connected to the inlet port 29 through an open / close valve 32. When the opening / closing valve 32 is opened, inert gas such as nitrogen, carbon dioxide or the like is introduced into the heating cylinder 2 from the inlet port 29.
    An operation of the injection molding system according to the embodiment of the present invention will now be described. The heating cylinder 2 is heated to rotate the screw 3 in the forward direction, and the resin material is supplied from a hopper (not shown). The supplied resin material is melted by the heat of the heating cylinder 2 and due to the heat by the shear force of the rotation of the screw 3, it is conveyed to the front side, and is compressed in the first compression section 6. Since the pressure of the molten resin in the first compression section 6 is high, the cone valve 22 in the sealing structure 7 opens and the molten resin is conveyed into the decompression relaxation section 5. Then, the molten resin is conveyed to the decompression section 9 via the decompression-relaxation section 5. As described above, since the screw groove in the decompression section 9 is deep, the pressure of the molten resin becomes low and the difference between the pressure in the / 30 • ·
    Decompression section 9 and the pressure in the first compression section 6 is large. However, when the molten resin flows through the two flat groove portions 13 and 13 of the decompression relaxation section 5, the pressure drops due to the displacement effect. Therefore, the resin pressure in the decompression section 9 remains stable. The
    Open / close valve 32 is opened to introduce the inert gas into the heating cylinder 2. The inert gas is introduced, for example, at a pressure of 5 MPa.
    Thereafter, the inert gas penetrates into the molten resin in the decompression section 9 and assumes a saturated state. Subsequently, when the screw 3 is rotated, in the decompression section 9, the molten resin into which the inert gas has entered in the saturated state is compressed in the second compression section 10 and is dosed at an initial head of the screw 3. When the predetermined amount is metered, the rotation of the screw 3 is interrupted. The screw 3 is driven in the axial direction to inject the molten resin into the mold. The inert gas causes bubbles in the molten resin in the mold, so that a molded foam product is obtained. At this time, if the rotation of the screw 3 is stopped and the screw is shifted in the axial direction, the backward flow of the inert gas becomes problematic. In the injection molding apparatus 1 according to the present embodiment, the flow in the backward direction is weakened because the decompression relaxation section 5, which exerts a displacement effect, is provided at two locations on the upstream side of the decompression section 9, and this applies even if the inert gas tries to flow in the reverse direction. Since the sealing structure 7 is provided on the upstream side of the decompression relaxation section 5, a sealing element is provided.
    Reverse flow essentially completely prevented. Therefore, the inert gas in the heating cylinder 2 does not flow in the reverse direction.
    Examples
    In an injection molding machine 1 having the screw 3 according to the present embodiment, an experiment was carried out to confirm that a molded foam product can be molded in a stable manner.
    Experiment 1
    The injection molding machine 1 according to the present embodiment shown in FIG. 1 was used, polypropylene with 20% of talc was used as a resin material to be heated and melted, and an inert gas was introduced from the injection port 29 and the molten resin containing the inert gas was injected into a predetermined shape to produce a molded foam product. In the injection molding process, a measurement standstill time for stopping the rotation of the screw 3 with a second was provided when the measurement or metering of the resin was completed, and then the screw 3 was shifted in the axial direction so that the injection was carried out. The molding cycle was repeated 30 times to obtain 30 molded foam products. The average weight of these molded foam products was 6.1 g, and the numerical value obtained by dividing the standard deviation by the average weight was 0.3%. It was confirmed in this experiment that the inert gas did not flow in the reverse direction beyond the sealing structure 7.
    / 30 ······· · · · • · · · · · · · • ♦ · · ·· ·· ·· ·
    Experiment 2
    An injection molding process was carried out using the same injection molding machine 1 as in Experiment 1 without introducing an inert gas. That is, an injection molded product was made without foaming. The molding cycle was repeated 30 times to obtain 30 molded products. The average weight of these molded products was 6.8 g, and the numerical value obtained by dividing the standard deviation by the average weight was 0.2%.
    Experiment 3
    The injection molding system 1 used in experiment 1 was changed, and an injection molding system was prepared in which the sealing structure 7 was removed. In an injection molding plant in which there was no sealing structure 7, a molded foam product was produced under the same conditions as were given in experiment 1. When the injection molding process was repeated several times, a phenomenon was observed, after which the inert gas in the heating cylinder 2 flowed in the reverse direction.
    Experiment 4
    A molded foam product was made using the prior art injection molding machine 60 shown in FIG. 4. The inert gas was introduced from the injection port 72, and the excess inert gas was discharged from the outlet port 73. The same resin and shape were used as in Experiment 1. The molding cycle was repeated 30 times to obtain 30 molded foam products. The average weight of these molded foam products was 6.1 g and the numerical value obtained by dividing the standard deviation by the average / 30 • ·· ···· · · · ···· · · · · • ·· · ·· · · ·· ·
    Weight was determined was 0.3%. In this experiment, it was confirmed that the inert gas did not flow in the reverse direction.
    comment
    The change in the weight of the molded foam product in Experiment 1 was 0.3%, but the fluctuation is not considered to be large because the fluctuation in the weight of the molded product without foaming from Experiment 2 was 0.2%. In other words, in Experiment 1 it can be said that the molded foam product was produced in a stable manner. This can be derived from the comparison with experiment 4. In other words, the backward flow of the inert gas is completely prevented in the injection molding machine 60 shown in FIG. 4, but the fluctuation in the weight of the molded foam product generated by the injection molding machine 60 was also 0.3%, which is equivalent to the variation in weight of the molded foam product of Experiment 1.
    In other words, it can be said that the injection molding system 1 according to the present embodiment, which was used in Experiment 1, was able to produce a homogeneous molded foam product in a stable manner. In experiment 1, no backward flow of the inert gas was observed, so that it can be said that the injection molding system 1, which is provided with the screw 3 according to the present embodiment, is suitable for producing molded foam products. It was further confirmed from the result of the experiment 3 that the sealing structure 7 is required. This is because a phenomenon has been observed that the inert gas flows in the heating cylinder 2 in the reverse direction when the molded foam product is generated by the injection molding machine without the sealing structure 7.
    / 30 • · • · · · · • · · · · · · • · · · • · · ·
    The injection molding system 1 according to the present embodiment can be changed in various ways. For example, it is possible to change the sealing structure 7. 2 (a) shows a sealing structure 7 'according to a further embodiment. The sealing structure 7 'according to this embodiment is formed by a region with a reduced diameter 35 in which the screw 3 becomes smaller in diameter, and is constructed with a sealing ring 36 which is provided with a predetermined gap in the region with a reduced diameter 35 , Since an outer peripheral surface of the seal ring 36 is in close contact with a bore of the heating cylinder 2, the molten resin does not flow from the outer peripheral surface of the cylinder. In other words, the inside of the heating cylinder 2 is divided in a liquid-tight manner by the sealing ring 36 into the first compression section 6 on the upstream side and the decompression relaxation section 5 on the downstream side thereof. The reduced diameter portion 35 in which the gap seal ring 36 is fitted is larger in diameter on the upstream side thereof so that a conical surface 37 is formed, and an end portion on the upstream side of the seal ring 36 is also conical Form trained. A contact area 38, in which the sealing ring 36 rests, is formed in the worm 3 on the front side of the area with a reduced diameter 35. When the molten resin is conveyed to the front by the rotation of the screw 3, the pressure of the molten resin in the first compression section 6 is higher than that in the decompression relaxation section 5, and the sealing ring 36 moves from the front with respect to the screw 3 and presses against the contact area 38. At this point in time, the conical end area of the sealing ring 36 detaches from the conical surface 37, and the first compression section 6 and the decompression relaxation section 5 protrude beyond the
    23/30 • · · ♦ · · · · · · • · · · · · · · • · · · · · ·· ·· ·
    The gap between the reduced diameter portion 35 and an inner peripheral surface of the seal ring 36 communicates with each other, and the molten resin flows downstream. A predetermined notch is formed on the end face of the seal ring 36 so that a flow path of the molten resin is ensured even when the seal ring 36 abuts the abutting portion 38. On the other hand, when the rotation of the screw 3 is stopped or the screw 3 is shifted in the axial direction, the pressure of the molten resin in the decompression-relaxation section 5 becomes higher than the pressure in the first compression section 6. Then, the sealing ring 36 is pressed, which Connection is blocked and the flow of the molten resin is prevented. In other words, backward flow of the resin is prevented.
    权利要求:
    Claims (5)
    [1]
    Claims:
    1. A screw (3) for an injection molding system (1), which is formed in a heating cylinder (2), a first compression section (6) for compressing a resin, a decompression section (9) for lowering a pressure of the resin and a second compression section (10) for compressing the resin from a rear side to a front side, the first compression section (6), the decompression section (9) and the second compression section (10) being formed according to the shape of the screw and an inert gas in the decompression section (9) is inserted, the screw (3) having:
    a predetermined sealing structure (7) for preventing reverse flow of the resin; and a decompression relaxation section (5) which is arranged on a downstream side of the sealing structure (7) and has a predetermined shape of a screw flight, the sealing structure (7) and the decompression relaxation section (5) between the first compression section (6) and the Decompression section (9) are arranged, and wherein in the decompression-relaxation section (5) at least two flat groove regions (13) are formed with a flat screw groove between the screw flights in the axial direction.
    [2]
    2. The screw (3) for an injection molding system (1) according to claim I,
    25/30 • · whereby the decompression relaxation section (5) is constructed by a multi-start thread from at least two threads.
    [3]
    3. The screw (3) for an injection molding system (1) according to claim
    1 or 2, the sealing structure (7) having:
    a seal (15) which is designed to partition the first compression section (6) and the decompression relaxation section (5) in a liquid-tight manner;
    a connection passage (18) which enables the first compression section (6) and the decompression relaxation section (5) to be connected to each other; and a valve mechanism (19) configured to:
    close the communication passage (18); and cause a molten resin in the first
    Compression section (6) flows into the decompression relaxation section (5) when the molten resin in the first compression section (6) exceeds a predetermined pressure.
    [4]
    4. The screw for an injection molding system according to claim 1 or
    2, the sealing structure (7 ') having:
    a reduced diameter area (35) in which a diameter of the screw (1) decreases; and a sealing ring (36) which is fitted in the reduced diameter area (35) with a predetermined gap therebetween and which is slidable with respect to a bore of the heating cylinder, and
    26/30 • ······· · · · ···· · · · · • · · · · · ·· ·· · where the area with reduced diameter (35) has a tapered surface (37) , and the sealing ring (36), when it lies on the tapering surface (37), blocks the connection between the first compression section (6) and the decompression relaxation section (5).
    [5]
    5. An injection molding system (1), with:
    of the screw (3) according to any one of claims 1 to 4, wherein the heating cylinder (2) has an injection port (29) for introducing an inert gas at a predetermined position corresponding to the decompression section (9).
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    同族专利:
    公开号 | 公开日
    DE102017217696B4|2019-06-13|
    JP6211664B1|2017-10-11|
    AT519150B1|2019-10-15|
    AT519150A3|2019-10-15|
    DE102017217696A1|2018-04-05|
    JP2018058267A|2018-04-12|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    JP2016197234A|JP6211664B1|2016-10-05|2016-10-05|Injection molding machine screw and injection molding machine|
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