• 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:
    The invention relates to a screw (3) for an injection molding machine (1), in which a heating cylinder (2) is provided with a first compression section (5), a pressure reduction section (6) and a second compression section (7), and in which a Inert gas is introduced into the depressurizing section (6). According to the invention, on a part of the screw (3) corresponding to the first compression section (5), there is a barrier flight (13) as a double flight which is a combination of a main flight (14) and a secondary flight (15) with a greater helix angle than the comprises a main ridge (14), and an annular dam ridge (18) having a predetermined width is formed downstream of, ie in front of, the barrier ridge (13). A sealing structure (20) for preventing backflow of the synthetic resin may be provided between the dam bar (18) and the depressurizing section (6).
    公开号:AT524081A2
    申请号:T9349/2019
    申请日:2019-08-23
    公开日:2022-02-15
    发明作者:Naito Akihiro；Araki Katsuyuki；Tamada Koichi；Uezono Hiromasa；Nakashima Hideaki
    申请人:Japan Steel Works Ltd；
    IPC主号:
    专利说明:

    The present invention relates to a screw for an injection molding machine for use in foam molding in which an inert gas is introduced into a molten synthetic resin and injected into a mold to form a foam molded one
    Product received, and continue to have an injection molding machine.
    STATE OF THE ART
    Molded products containing a large number of fine bubbles, i.e., foam molded products, are not only light in weight but also excellent in strength and can be used for a wide variety of purposes. In order to obtain a foam molded product by injection molding, a foaming agent must be mixed with a synthetic resin. As the foaming agent, chemical foaming agents such as azodicarbonamide, which decomposes under heat to generate a gas, and physical foaming agents, i.e., inert gases such as nitrogen and carbon dioxide, can be used. When an inert gas is used as the foaming agent, the inert gas is introduced at a predetermined pressure into the synthetic resin melted in a heating cylinder so that the inert gas is saturated in the synthetic resin. When injected into a mold, the pressure in the resin is released and the inert gas creates bubbles. When the resin cools and solidifies, a foam molded product is obtained. Because the physical foaming agent containing an inert gas is introduced into the synthetic resin under a high pressure and at a high temperature, a strong penetrating force is exerted and the physical foaming agent is easily and uniformly dispersed in the synthetic resin as compared with a chemical foaming agent. Therefore, the foam molded product obtained has excellent properties and is an uneven one
    Foam formation unlikely.
    PATENT LITERATURE
    Patent Literature 1: Japanese Patent No. 6211664
    Patent Literature 2: JP-A-2002-79545
    SUMMARY OF THE INVENTION
    PROBLEM
    Patent Literature 1 describes an injection molding machine that can stably and correctly introduce an inert gas into a molten synthetic resin and perform foam molding correctly. Furthermore, Patent Literature 2 describes a
    Injection molding machine for performing foam molding.
    The injection molding machines described in Patent Literatures 1 and 2 have excellent characteristics. Still, there is room for improvement on the injection molding machines. In the injection molding machine of Patent Literature 1, since a sealing structure and a relief portion must be provided on a screw, the length of the screw is increased accordingly. This raises the problem of a longer machine length. The injection molding machine described in Patent Literature 2 has a short machine length, however, the screw is not provided with a sealing structure or the like and therefore
    backflow of the inert gas is possible.
    It is an object of the present invention to provide a screw for an injection molding machine with a sufficiently short machine length in which there is no risk of gas leaking to an upstream side of the screw in a heating cylinder during a molding cycle or during a stop due to maintenance or the like flows or leaks, and so no backflow in an injection molding machine for inserting a
    physical foaming agent with a gas contained therein in
    continue to provide an injection molding machine.
    TROUBLESHOOTING
    In order to achieve the above object, according to the present invention, a screw for an injection molding machine, in which a first compression section in which a synthetic resin is compressed, a depressurization section in which the pressure of the synthetic resin is reduced, and a second compression section in in which the synthetic resin is compressed, are arranged from a rear side to a front side and in which gas is introduced into the depressurizing section, and an injection molding machine. According to the present invention, at a part of the scroll corresponding to the first compression section, a barrier ridge is provided as a double ridge comprising a combination of a main ridge and a sub ridge having a larger helix angle than the main ridge, and is an annular dam ridge having a predetermined width downstream provided by, ie in front of the barrier web. A sealing structure for preventing backflow of the synthetic resin can be provided between the dam web and the
    Be provided pressure reduction section.
    In order to achieve the above object of the invention, the screw for an injection molding machine for foam molding and the injection molding machine according to the present invention
    Invention has the features of the following items [1] to [5].
    [1] Screw for an injection molding machine for foam molding, in which a first compression section in which a synthetic resin is compressed, a depressurization section in which the
    Pressure of the synthetic resin is reduced, and a second
    is formed in front of the barrier web.
    [2] In the screw according to [1], the screw is provided with a predetermined sealing structure to prevent backflow of the synthetic resin between the dam web and the
    to prevent depressurization section.
    [3] In the scroll according to [2], the sealing structure includes: a gasket configured to liquid-tightly separate the first compression section from the depressurization section; a connection passage configured to connect the first compression section and the depressurization section; and a valve mechanism configured to close the communication passage and cause a flow of a molten synthetic resin into the depressurizing section when the molten synthetic resin is in the first
    Compression section exceeds a predetermined pressure.
    [4] In the scroll according to [2], the sealing structure includes: a reduced-diameter part in which the scroll is reduced in diameter; and a seal ring that is fitted onto the reduced-diameter part with a predetermined clearance therebetween and liquid-tightly slides with respect to a bore of the heating cylinder, wherein a tapered surface is formed on the reduced-diameter part to
    a connection between the first compression section and
    sealing ring is seated.
    [5] An injection molding machine including the screw according to any one of [1] to [4], wherein the heating cylinder is provided with an introduction port that introduces gas at a predetermined position into
    Correspondence to the depressurization section introduces.
    ADVANTAGEOUS EFFECTS OF THE INVENTION
    As described above, the present invention provides a screw of an injection molding machine in which the first compression section in which the synthetic resin is compressed, the depressurization section in which the pressure of the synthetic resin is reduced and the second compression section in which the synthetic resin is compressed in the heating cylinder are provided from the rear side to the front side by the shape of the screw and the gas is introduced into the depressurization section, and further the injection molding machine. In such a scroll, backflow of the gas when rotation of the scroll is stopped is generally a problem. According to the present invention, at the part of the scroll corresponding to the first compression section, the barrier rib comprising the combination of the main rib and the sub rib having a larger helix angle than the main rib is formed, and the annular dam rib is formed with a predetermined width in front of the barrier rib. As described in more detail below, a seal formed from a thin layer of melted synthetic resin is formed in the barrier ridge and dam ridge in the heating cylinder. The seal designed in this way prevents the gas from flowing back. According to the invention, since two types of seals are formed at two positions, namely, the barrier ridge and the dam ridge, backflow of the gas becomes substantial and complete
    prevented when the rotation of the auger for about 10
    Auger is stopped for several tens of minutes.
    BRIEF DESCRIPTION OF THE DRAWINGS
    1 is a side sectional view of an injection molding machine with a screw according to a first embodiment of the invention
    present invention.
    2 is a side sectional view of an injection molding machine with a screw according to a second embodiment of the invention
    present invention.
    3 is a schematic view showing a sealing structure on the screw according to the first embodiment of the present invention, and a sectional view of the sealing structure parallel to the axis of the screw
    snail is.
    FIG. 4 is a schematic view showing a sealing structure on the screw according to the first
    Embodiment of the present invention shows and one
    snail is.
    Fig. 5 is a side sectional view showing part of the injection molding machine with a screw according to a
    Embodiment of the present invention shows.
    DESCRIPTION OF EMBODIMENTS
    Embodiments of the present invention are described below. As shown in FIG. 1 , an injection molding machine according to a first embodiment of the present invention includes a heating cylinder 2 and a screw that can be driven in a rotational direction and an axial direction in the heating cylinder 2 . The heating cylinder 2 is provided with a hopper on its rear side, i.e., upstream side, and a spray nozzle on its front side, i.e., downstream side. A plurality of band heaters are wound around an outer peripheral surface of the heating cylinder 2 . The hopper, spray nozzle and band heaters are not in
    shown in the figure.
    A relatively simple configuration for an injection molding machine for foam molding using an inert gas is a configuration in which three sections, two compression sections and one depressurizing section, are formed in a heating cylinder and a gas is introduced into the depressurizing section. An injection molding machine 1 according to the first embodiment of the present invention has such a simple configuration that three sections are formed in the heating cylinder 2 . In the heating cylinder 2 of the injection molding machine 1, by the predetermined shape of the screw 3, a first compression section 5, a depressurization section 6 and a second compression section 7 are closed from the rear side
    the front side, i.e. from the upstream side
    supplied to an inert gas introduction part 10 via an on/off valve 11
    Snail 3 measured.
    The screw 3 of the injection molding machine 1 according to the first embodiment of the present invention has some features at a part corresponding to the first compression section 5 . A first feature is that a barrier ridge 13, which is a double ridge having a predetermined shape, is formed at this part. Specifically, a spiral-shaped single ridge 12 protruding from an outer surface of a main body of the screw 3 is formed at the part of the screw 3 located at the feeding part 5a of the first compression section 5. As shown in FIG. The barrier web 13 is formed on the part of the screw 3 arranged on the compression part 5b, on the part of the screw 3 arranged on the measuring part 5c or on a part of the screw 3 arranged on the compression part 5b and the measuring part 5c in such a way that it is attached to the individual web 12 connects. The barrier flight 13 comprises a spiral main flight 14 and a secondary flight 15 protruding from the outer surface of the main body of the screw 3. The main flight 14 has the same helix angle (angle formed by the flight with respect to a radial direction of the screw 3) as the single one Jetty 12 up. The side bar 15 has a larger
    Pitch angle than the main web 14 on. Therefore are in the
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    Barrier web 13, the main web 14 and the sub-web 15 connected to each other at the front and rear end parts. In this embodiment, the height of the sub-land 15 is slightly lower than the height of the main land 14. Therefore, a predetermined clearance is formed between an upper part of the sub-land 15 and a bore of the heating cylinder 2. As described later, as the screw 3 rotates, the unmolten solid resin is deposited on the front side, ie, the downstream side of the sub-landing 15, while the molten resin flows through the predetermined gap and settles on the rear side , ie the downstream side of the sub-landing 15 accumulates. The presence of the molten synthetic resin in the predetermined space provides a sealing effect for preventing backflow of the
    noble gas.
    A second feature of the screw 3 of the injection molding machine 1 according to the first embodiment of the present invention is that a dam ridge 18 is formed in front of the barrier ridge 13, that is, on the downstream side thereof, at the part of the screw 3 located in the first compression section 5 . The dam ridge 18 consists of an annular ridge having a predetermined width projecting outward in the radial direction. It can also be said that the ridge has a columnar shape whose height is considerably lower than the diameter. Because a clearance formed between an upper part of the dam bar 18 and the bore of the heating cylinder 2 is narrow, even if there is unmelted solid synthetic resin, the unmelted synthetic resin is blocked by the dam bar 18 so that it is not transported forward. The presence of the molten synthetic resin in this space provides a sealing effect for preventing a so-called backflow of the upstream side of the resin
    Snail 3 flowing inert gas as the barrier web 13 before. the
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    Dam bar 18 may be provided contiguous to barrier bar 13 or may be provided at a predetermined distance with respect to barrier bar 13 . For example, the predetermined distance is 0.1D or more, or 0.5D or more des
    diameter D of the heating cylinder.
    A third feature of the screw 3 of the injection molding machine 1 according to the first embodiment of the present invention is that a sealing structure 20 is provided at the most downstream part of the first compression section 5 . As shown in detail in Figure 3, the seal assembly 20 includes a seal 21 and a flow control mechanism 23 which performs a pressure adjustment action. The seal 21 is slidably fitted into a predetermined groove in an outer peripheral surface of the worm 3 . Although the heating cylinder 2 is not shown in FIG. 3, the gasket 21 slides while an outer peripheral surface of the gasket is in contact with the bore of the heating cylinder 2 smoothly. The gasket 21 prevents the molten resin from flowing, and the inside of the heating cylinder 2 is liquid-tightly separated into the first compression section 5 on the upstream side and the depressurizing section 6 on the downstream side. The seal assembly 20 is provided with one or more flow control mechanisms 23 . The flow control mechanism 23 includes a communication passage 24 opening in the scroll 3 so as to connect the first compression section 5 to the depressurization section 6, and a valve mechanism 25 configured to open and close the communication passage 24. A middle part of the communication passage 24 has a reduced diameter with a tapered shape so that a tapered seating surface 27 is formed. When a head portion 29 of a poppet valve 28 of the valve mechanism 25 is seated on the seating surface 27, the communication passage 24 is closed. The poppet valve 28 also includes the head part 29
    an umbrella shape and a shaft part 31, the shaft part
    31 is provided with a plurality of disc springs 33, 33... . In this way, the poppet valve 28 provided with the disc springs 33, 33... is received in a holder 34 having a hole with a bottom. The bracket 34 is threadingly fixed to a female thread formed in an inner peripheral surface of the connection passage 24 through a male thread formed on its outer peripheral surface. Therefore, the poppet valve 28 is biased by the disk springs 33, 33..., the head portion 29 is pressed against the seat surface 27, and the communication passage 24 is closed. When the molten synthetic resin in the first compression section 5 reaches a predetermined pressure, the poppet valve 28 retreats against the bias of the disk springs 33, 33... . Then, a synthetic resin passage 35 opening in the holder 34 connects the compression section 5 to the depressurization section 6, and the molten synthetic resin flows into the depressurization section 6. When the pressure in the first compression section 5 is equal to the pressure in the depressurization section 6 or when the pressure in the When the depressurizing section 6 is higher than the pressure in the first compression section 5, the poppet valve 28 sits on the seat surface 27 and is disconnected, so that the molten synthetic resin flows back from the depressurizing section 6 to the first
    Compression section 5 is prevented.
    The operation of the injection molding machine 1 according to the first embodiment of the present invention will be described below. The heating cylinder 2 is heated and the screw is rotated to feed synthetic resin pellets into the heating cylinder 2. Then, the synthetic resin pellets are transported in the heating cylinder 2 while being heated to be melted in the first compression section 5 . When, as shown in FIG. 5, the synthetic resin in the barrier rib 13 is transported forward
    is, sees the side bar 15, which has a larger pitch angle
    than the main ridge 14 has a greater effect of transporting the resin forward. Therefore, the unmolten solid synthetic resin is forcibly pushed forward by the sub-ridge 15 . In contrast, the molten resin can flow through the gap between the upper part of the sub-land 15 and the bore of the heating cylinder 2 so that the molten resin flows to behind the sub-land 14 . As a result, the unmolten solid resin is transported downstream and accumulates in front of the sub-land 15, and the molten resin is transported downstream and an area behind the sub-land 15 is filled with the molten resin. The molten synthetic resin is kneaded and compressed and passes through the dam bar 18. Because the clearance between the upper part of the dam bar 18 and the bore of the heating cylinder 2 is small, even if the non-molten solid synthetic resin is present, the non-molten one becomes , solid synthetic resin blocked by the dam bar 18. This ensures that only the melted resin is transported forward. The molten synthetic resin is transported to the depressurizing section 6 through the sealing structure 20 . In the depressurizing section 6, because the screw groove is deep, the pressure of the synthetic resin is reduced. Therefore, a gas phase is formed in the depressurizing section 6 inside the heating cylinder 2 . The inert gas is introduced from the inert gas introduction part 9 . The molten synthetic resin into which the inert gas is introduced is compressed and kneaded in the second compression section 7 and transported to the front side of the screw 3 . So a measurement is made. When the measurement is completed, the molten resin is ejected. That is, the rotation of the worm 3 is stopped and the worm 3 is driven in the axial direction. Then a cavity becomes one
    Mold filled with the melted resin. The noble gas sees
    foaming to produce a foam molded product
    obtain.
    When the screw 3 rotates, a pressure difference of the synthetic resin in the sections 5, 6 and 7 inside the heating cylinder 2 is generated. However, when a molding cycle is interrupted and the screw 3 is stopped for a long period of time due to maintenance or the like, the pressure difference of the molten synthetic resin in the heating cylinder 2 is reduced. Therefore, there is a risk that the inert gas flows back into the heating cylinder 2 or the molten resin is pushed out by the inert gas and flows back. In the injection molding machine 1 according to the first embodiment of the present invention, such backflow is substantially and completely prevented. First, the seal assembly 20 prevents back flow. Because the sealing structure 20 includes the gasket 21 and the valve mechanism 25, the effect of preventing backflow is strong. Second, the dam bar 18 prevents backflow. This is because the clearance between the top of the dam ridge 18 and the bore of the heating cylinder 2 is small, so this clearance is filled with the molten synthetic resin to exhibit a high sealing effect. And the barrier web 13 also prevents backflow. Because the clearance between the upper part of the sub-landing 15 and the bore of the heating cylinder 2 is small, a high sealing effect is produced by the molten synthetic resin filled in this part. The inert gas or the molten synthetic resin does not flow back beyond the side ridge 15 also. In the injection molding machine 1 according to the first embodiment of the present invention, since the barrier ridge 13, the dam ridge 18 and the sealing structure 20 are provided in the first compression section 5, backflow of the inert gas or the synthetic resin can be substantially and completely
    be prevented.
    The injection molding machine 1 according to the present invention can be modified in various ways. For example, in practicing the present invention, the seal assembly 20 is not always mandatory and may be omitted. 2 shows an injection molding machine 1' according to a second embodiment of the present invention, in which the sealing structure 20 is omitted. The same components as in the injection molding machine 1 according to the first embodiment are denoted by the same reference numerals, and a repeated description of these components is omitted here. In the injection molding machine 1 according to this embodiment, only the barrier ridge 13 and the dam ridge 18 are provided as a structure for preventing backflow. Due to the sealing effect of the molten resin filled in the narrow space, backflow of the inert gas or resin can be prevented even if a screw 3' is stopped for about 10 minutes. Because the sealing structure 20 having a complex structure can be omitted in the injection molding machine 1' according to the second embodiment, the injection molding machine 1'
    be produced inexpensively.
    In the injection molding machine 1 according to the first embodiment, the seal structure 20 can be replaced with a seal structure 20' having a simple structure as shown in FIG. The seal structure 20' includes a reduced-diameter portion 40 in which the diameter of the screw 3 is reduced, and a seal ring 41 provided in the reduced-diameter portion 40 with a predetermined clearance therebetween. An outer peripheral surface of the seal ring 41 is in smooth contact with the bore of the heating cylinder 2, and the molten synthetic resin does not flow from the outer peripheral surface. That is, the inside of the heating cylinder 2 is liquid-tightly sealed by the seal ring 41 in the first compression portion 5 on the upstream side and the
    Depressurizing section 6 on the downstream
    page is separated. The reduced-diameter portion 40 on which the seal ring 41 is fitted with a clearance therebetween has an enlarged diameter on the upstream side to form a tapered surface 42 . And an end part of the seal ring 41 on the upstream side is also formed in a tapered shape. In the worm 3, an abutting portion 44 against which the seal ring 41 abuts is formed on the front side of the reduced-diameter portion 40. As shown in FIG. When the screw 3 is rotated to feed the molten synthetic resin forward, the pressure of the molten synthetic resin in the first compression section 5 is higher than the pressure of the molten synthetic resin in the depressurizing section 6, and the seal ring 41 moves forward with respect to the Screw 3 and is pressed against the abutment part 44. At this time, the tapered end portion of the seal ring 41 is separated from the tapered surface 42, and the first compression portion 5 and the depressurization portion 6 are connected to each other through a clearance between the reduced-diameter portion 40 and an inner peripheral surface of the seal ring 41, so that the molten resin flows downstream. A predetermined recess is formed in an end surface of the seal ring 41 so that a flow path of the molten synthetic resin is secured even if the seal ring 41 abuts against the abutment part 44 . On the other hand, during injection or the like, the seal ring 41 is seated on the tapered surface 42, the connection is broken, and the flow of the molten resin is suppressed. This way there will be a reflux
    prevented.
    In addition, the injection molding machines 1 and 1' according to the embodiments of the present invention can be modified in various ways. For example, in the
    first embodiment, the worm groove of the worm 3 such
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    formed that the first compression section 5 includes the feeding part 5a, the compression part 5b and the measuring part 5c. Alternatively, the screw groove of the screw 3 may be formed such that, for example, the first compression section 5 includes the feeding part 5a and the compression part 5b but not the metering part 5c, or another configuration may also be used. No particular specification is made here regarding the synthetic resin as long as it can be melted, compressed, kneaded and fed forward. Correspondingly, the described second compression section 7 contains the compression part 7b and the measuring part 7c. However, the invention is not limited to such a configuration as long as the molten synthetic resin and the inert gas can be kneaded and at the same time can be compressed and transported forward. The shape of the upper part of the single ridge 12 and the barrier ridge 13 formed on the scroll 3 has not been described in detail. The upper part may be formed in a flat shape so that a clearance with the bore of the heating cylinder 2 is constant, or may be formed in a stepped shape with a changing clearance. Although not described in detail, the second compression section 7 may comprise a single ridge, a double ridge, or a multi-row ridge composed of three or more ridges. In the embodiment described, the inert gas is fed into the heating cylinder 2 via the on/off valve 11 . The on/off valve 11 can be opened and closed synchronously with the molding cycle or can be kept open at all times. In addition, the heating cylinder 2 may be configured such that the inert gas is always introduced into the heating cylinder 2 and no on/off valve 11 is provided. Preferably, the pressure of the synthetic resin in the depressurizing section 6 into which the gas is introduced becomes a low pressure close to the atmospheric pressure
    reduced. However, this is not always necessary as long as
    the pressure of the synthetic resin is lower than that in the first compression section 5. If the inert gas is supplied with a gas pressure higher than this pressure, introduction is possible. The gas supplied to the heating cylinder 2 has been described as an inert gas such as nitrogen or carbon dioxide, but the present invention is not limited thereto. For example, hydrocarbons such as butane and gases such as hydrofluorocarbons can also be used. The present invention has been limited by the embodiments above, however, the scope of the invention is not limited to the embodiments described above and various modifications can be made to the embodiments described herein without the reason
    departing from the scope of the invention.
    EXAMPLE 1
    In order to confirm that according to the invention, foam molding can be carried out stably and no backflow of the inert gas or resin occurs when the rotation of the screws 3 and 3' occurs in the injection molding machines 1 and 1'
    experiment performed.
    [Experimental Method]
    The following five injection molding machines were prepared.
    Example 1: An injection molding machine 1 according to the first embodiment of the present invention. That is, the injection molding machine 1, which has the barrier web 13, the dam web 18
    and the seal assembly 20 includes.
    Example 2: An injection molding machine 1' according to the second embodiment of the present invention. That is, the injection molding machine 1' having the barrier ridge 13 and the dam ridge
    18 contains.
    Comparative Example 1: An injection molding machine which does not include a barrier ridge 13 nor a dam ridge 18, has a seal structure having the same structure as the seal structure 20 and one between the seal structure and the depressurizing section
    having trained relaxation section.
    Comparative Example 2 An injection molding machine 1' according to the second embodiment of the present invention without a barrier ridge 13. That is, an injection molding machine having only the
    Dam bar 18 contains.
    Comparative Example 3: An injection molding machine 1' according to the second embodiment of the present invention without a dam bar 18. That is, an injection molding machine having only the
    Barrier web 13 contains.
    In these five injection molding machines, a test was conducted to see whether foam molding could be stably performed, and a test was conducted to see whether backflow could be reliably prevented when the rotation of the screw was stopped during the feeding of the inert gas for 10 mins
    was stopped.
    The resins used were a PP resin and a PA66 resin. A nitrogen gas was supplied as the inert gas. The nitrogen gas was supplied such that the pressure was 8 MPa for the PP resin and the pressure was 6 MPa for the PA66
    resin fraud.
    [test results]
    The test results are given in the following table.
    [Table 1] sealing | Dams | Barrier |PP- PA66-—ngs- bridge bridge synthetic resin, synthetic resin, structure gas pressure 8 gas pressure 6 MPa MPa cast | resistance | casting | Resist and and within within 1b of 10 10 minutes minutes Examples OOO Oo Oo 11 Examples |- OO OO OO 12 Comparison ©) _ _ OOOO chsexample ı 21 (*) Comparison |- O — XXXX chsexample 12 Comparison |- _ OOOOX chsexample 13
    * A relaxation section is provided
    In Examples 1 and 2 and Comparative Example 1, the foam molding is repeated and can be stably performed even if the rotation of the screw is stopped for 10 minutes, and no backflow of the inert gas or resin occurs. If foam casting is restarted after 10 minutes, foam casting can be restarted normally. On the other hand, in Comparative Example 2, when the foam molding is repeated, backflow of the inert gas and the resin occurs. A reflux of the noble gas is observed when the snail
    only stopped for a few minutes. By doing
    Comparative Example 3, casting can be stably performed when foam casting is repeated. But if a PA66 resin is used and the rotation of the screw for 10
    minutes, backflow of the inert gas occurs.
    [explanation]
    It can be confirmed that when the injection molding machine 1 with a short machine length has three sections, namely the first compression section 5, the depressurization section 6 and the second compression section 7 inside the heating cylinder 2, and the screw 3 with the barrier ridge 13 and the dam ridge 18 is provided at the part corresponding to the first compression section 13, the foam molding can be stably performed and backflow of the inert gas or resin can be prevented even if the rotation of the screw 3 is stopped for 10 minutes such as for maintenance. It can be said that the combination of the barrier ridge 13 and the dam ridge 18 can effectively prevent backflow of the inert gas. In the experiment, the injection molding machine of Comparative Example 2 could not stably perform the foam molding, but the molding can be performed if the pressure of the inert gas is made sufficiently smaller than the pressure therein
    Experiment.
    The features of the embodiments of the screw for an injection molding machine for foam molding and the injection molding machine according to the present invention are described in Fig
    Briefly summarized below in points [1] to [5].
    [1] Screw (3) for an injection molding machine for foam molding, in which a first compression section (5) in which a synthetic resin is compressed, a depressurization section (6) in which a pressure of the synthetic resin is reduced, and a second
    Compression section (7) in which the synthetic resin is compressed
    is provided in a heating cylinder (2) from a rear side to a front side by the shape of the scroll (3) and in which a gas is introduced into the depressurizing section (6), the scroll being at one of the first compression sections (5th ) the part corresponding to the screw (3) comprises: a barrier flight (13) comprising a combination of a main flight (14) and a secondary flight (15) with a greater helix angle than the main flight (14); and an annular dam bar (18) having a predetermined width, the
    is formed in front of the barrier web (13).
    [2] In the screw (3) according to [1], the screw (3) is provided with a predetermined sealing structure (20) to prevent backflow of the synthetic resin between the dam web (18) and the
    To prevent pressure reduction section (6).
    [3] In the scroll (3) according to [2], the sealing structure (20) includes: a packing (21) configured to liquid-tightly separate the first compression portion
    (5) from the depressurizing section (6); a connection passage configured to connect the first compression section (5) to the depressurization section (6); and a valve mechanism configured to close the communication passage and cause a flow of a molten synthetic resin into the depressurizing section (6) when the molten synthetic resin in the first compression section (5) enters
    exceeds the predetermined pressure.
    [4] In the worm (3) according to [2], the sealing structure (20) comprises: a reduced-diameter part (40) in which the diameter of the worm (3) is reduced; and a sealing ring (41) fitted on the reduced-diameter portion (40) with a predetermined clearance therebetween and liquid-tight with respect to a bore of the heating cylinder
    (2) slides, with a tapered surface (42) on the
    diameter-reduced part (40) is designed to block communication between the first compression section (5) and the pressure reduction section (6) when the
    Sealing ring (41) is seated.
    [5] Injection molding machine (1) including the screw (3) according to any one of [1] to [4], wherein the heating cylinder (2) is provided with an introduction port that introduces gas at a predetermined position corresponding to the depressurizing portion ( 6)
    introduces.
    The present invention has been described in detail with reference to specific embodiments, and it should be apparent to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the spirit
    Scope of the invention is left.
    The present application is based on Japanese Patent Application Application No. 2018-158759 filed on Aug. 27, 2018, the contents of which are available here
    reference is included. INDUSTRIAL APPLICABILITY
    According to the present invention, a screw for an injection molding machine with a sufficiently short machine length in which there is no fear that a gas flows to an upstream side of the screw in a heating cylinder during a molding cycle or during a stop caused by maintenance or the like or leaks, and hence backflow does not occur in an injection molding machine for introducing a physical foaming agent with a gas contained therein into a molten synthetic resin for molding a foam molded product, so that the screw can perform molding stably and also in a very limited one
    Installation space can be installed, and continue one
    24/33
    Injection molding machine are provided. The invention can thus be useful on a screw for an injection molding machine and on
    an injection molding machine can be used.
    LIST OF REFERENCE MARKS
    1 injection molding machine
    2 heating cylinders
    3 snail
    5 first compression section 6 depressurization section
    7 second compression section 9 noble gas introduction part
    12 single bridge
    13 barrier footbridge
    14 main jetty
    15 side jetty
    18 causeway
    20 sealing structure
    21 seal
    23 flow control mechanism 24 connecting passage
    24 valve mechanism
    27 seat
    28 poppet valve
    33 Woodruff key
    40 reduced diameter part 41 sealing ring
    42 tapered surface
    44 bump part
    权利要求:
    Claims (3)
    [1]
    A screw for an injection molding machine for foam molding, in which a first compression section in which a synthetic resin is compressed, a depressurization section in which the synthetic resin is depressurized, and a second compression section in which the synthetic resin is compressed, in a heating cylinder are provided from a rear side to a front side by the shape of the scroll and in which a gas is introduced into the depressurizing section, the scroll being at one of the first compression section of the
    Snail relevant part includes:
    a barrier jetty which is a combination of a main jetty and a secondary jetty with a larger one
    pitch angle than the main ridge includes, and
    an annular dam bar with a predetermined width,
    which is formed in front of the barrier web.
    [2]
    2. Snail according to claim 1, wherein the snail is provided with a predetermined sealing structure to prevent backflow of the synthetic resin between the dam web and the
    to prevent depressurization section.
    [3]
    3. Screw according to claim 2, wherein the sealing structure
    includes:
    a seal configured to liquid-tightly separate the first compression section from the
    depressurization section,
    a connection passage configured to connect the first compression section to the
    pressure reduction section, and
    a valve mechanism configured to close the communication passage and cause a flow of a molten synthetic resin into the depressurizing section when the molten synthetic resin enters the first compression section
    exceeds the predetermined pressure.
    The auger of claim 2, wherein the sealing structure
    includes:
    a reduced-diameter part in which the diameter
    the snail is reduced, and
    a seal ring fitted on the reduced-diameter portion with a predetermined clearance therebetween and liquid-tight with respect to a bore
    of the heating cylinder slides,
    wherein a tapered surface is formed on the reduced-diameter part to block communication between the first compression section and the decompression section when the
    sealing ring is seated.
    An injection molding machine including the screw according to any one of claims 1 to 4, wherein the heating cylinder is provided with an introduction port that introduces gas at a predetermined position corresponding to that
    Introduces pressure reduction section.
    27733
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    同族专利:
    公开号 | 公开日
    US20210178648A1|2021-06-17|
    KR20210042923A|2021-04-20|
    TW202017727A|2020-05-16|
    CN112601647A|2021-04-02|
    JP2020032547A|2020-03-05|
    JP6762679B2|2020-09-30|
    DE112019004310T5|2021-06-17|
    WO2020045265A1|2020-03-05|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JP2003103587A|2001-10-02|2003-04-09|Mitsubishi Heavy Ind Ltd|Plasticizing device and method for injecting gas into plasticizing device|
    JP2003117973A|2001-10-17|2003-04-23|Mitsubishi Heavy Ind Ltd|Resin plasticating screw|
    JP2007054995A|2005-08-23|2007-03-08|Ube Machinery Corporation Ltd|Injection divice|
    JP2008272999A|2007-04-27|2008-11-13|Sekisui Chem Co Ltd|Screw in vinyl chloride type resin foam molding machine|
    WO2017007032A1|2015-07-08|2017-01-12|日立マクセル株式会社|Process and device for producing molded foam|
    JPS6211664B2|1981-07-16|1987-03-13|Sekisui Plastics|
    JP4233240B2|2000-06-22|2009-03-04|三井化学株式会社|Injection foam molding method, and injection molding machine and resin composition suitable therefor|
    JP6211664B1|2016-10-05|2017-10-11|株式会社日本製鋼所|Injection molding machine screw and injection molding machine|CN113370489B|2021-07-12|2022-03-04|苏州金韦尔机械有限公司|Screw extruder with water-rotating cavity|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    JP2018158759A|JP6762679B2|2018-08-27|2018-08-27|Injection molding machine screw and injection molding machine for foam molding|
    PCT/JP2019/032977|WO2020045265A1|2018-08-27|2019-08-23|Screw for injection molding machine for foam molding, and injection molding machine|
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