JP2014117889A - Injection device of injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inline type plunger type injection device capable of preventing the back flow of molten resin in a measuring step and an injection filling step without complicating the structure.SOLUTION: The injection device of an injection molding machine comprises: a heating cylinder 15; a screw rotatably arranged in the heating cylinder 15; a plunger 17 arranged at the hollow part of the screw 16 coaxially rotatably with the screw 16 an also movably to the axial direction; a flight 17a formed in the prescribed range of the outer circumferential face on the injection nozzle side of the plunger 17; a check ring 18 arranged at the injection nozzle side of the plunger 17; a first resin flow passage 10 formed between the inner circumferential face of the heating cylinder 15 and the outer circumferential face of the screw 16; and a communication resin flow passage 11 communicating the resin flow passage 10 with the outer circumferential face of the plunger 17 at which the flight 17a is formed in a measuring step.

Description

  The present invention relates to an injection apparatus used for a resin injection molding machine.

  The injection device of a general injection molding machine has a heating means such as an electric heater arranged on the outer peripheral surface thereof, a heating provided with an injection nozzle at one end and a material supply unit such as a material supply hopper at the other end. The cylinder is constituted by a screw disposed in the heating cylinder so as to be rotatable about the longitudinal axis and movable in the axial direction. Further, on the outer peripheral surface of the screw, resin pellets or the like supplied from the material supply unit by rotating the screw in a resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw. A flight for allowing the resin material to flow toward the injection nozzle is continuously formed. The shape and size of the flight are designed according to each specification so that the resin material can be supplied (flowed), compressed, and measured from the material supply unit side to the injection nozzle side. In order to simplify the explanation, the injection nozzle side of the heating cylinder is “front” of the injection device, the material supply side is “rear”, and the movement of the screw or resin material in the respective directions is “forward” and “ “Retreat”.

  Furthermore, a screw head is arranged at the front end of the screw, and a check ring (also called a check ring) is arranged between the screw head and the screw so as to be movable by a predetermined amount in the longitudinal axis direction of the screw. Is done. Resin material such as resin pellets supplied from the material supply unit is used in addition to the thermal energy of the heating means arranged on the outer peripheral surface of the heating cylinder while the screw is rotated and flowed forward by the flight. It becomes a molten state by the thermal energy of the shear heat by the rotational force (plasticization process). The molten resin material (molten resin) is then injected through the groove of the screw head while moving the check ring forward by the resin pressure due to the flow to open the resin flow path. It reaches between the nozzle and screw head. At this time, since the injection nozzle is closed by the injection nozzle or the resin shut-off switching valve disposed at the resin inlet of the fixed mold to which the injection nozzle is docked, the injection nozzle and the screw head The resin pressure of the molten resin reached in the middle also acts on the screw head, causing the entire screw to retreat. The molten resin is continuously stored in the space between the injection nozzle and the screw head in the heating cylinder, which is formed in conjunction with the retreat. Until this space is expanded and a predetermined amount of molten resin is stored, the rotation of the screw and the retreat of the entire screw are continued, and the open state of the check ring is maintained (metering step). A space in which the molten resin is stored is referred to as a storage portion.

  After a predetermined amount of molten resin is stored in the storage portion between the injection nozzle and the screw head, the rotation of the screw is stopped and the screw is advanced at a predetermined speed and a predetermined force. The non-return ring is moved backward by the resin pressure of the molten resin flowing backward, and the gap between the resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw and the screw head is sealed. The molten resin is prevented from flowing back into the resin flow path, and is injected and filled into the mold cavity formed in the fixed mold and the movable mold in which the injection nozzle is docked via the injection nozzle (injection filling process). ).

  Such an injection device is called an in-line screw type injection device. As described above, the inline screw type injection device is configured so that the screw moves backward in conjunction with the increase in the amount of molten resin stored in front of the screw from the start to the completion of the weighing process, while the position of the material supply unit Therefore, the distance (plasticization flow length) of the resin flow path for plasticizing (melting) the resin becomes shorter in proportion to the retraction amount of the screw from the start to the completion of the measurement process. For this reason, as the metering process approaches completion, the shortening of the plasticization flow length becomes remarkable, and problems such as a decrease in the plasticizing ability of the injection apparatus and a variation in the plasticized state of the resin material have been pointed out.

  In order to solve the problem of such an in-line screw type injection device, an injection device of an injection molding machine such as Patent Literature 1 and Patent Literature 2 has been proposed.

  In Patent Document 1, a plasticizing screw (plunger) having a plastic shape screw (screw) rotatably disposed in a plasticizing cylinder (heating cylinder) and having a tip shape as a screw (flight) is provided as a plasticizing screw. An injection device for an injection molding machine is disclosed in which the rotation speed of the injection plunger is made larger than the rotation speed of the plasticizing screw to prevent resin leakage from the plunger. .

  That is, the injection device of the injection molding machine of Patent Document 1 is dedicated to the plasticizing process only for the rotational operation without moving the screw in the longitudinal direction, and the resin material plasticized by the screw is coaxial with the screw in the screw. The plasticizing flow length is made constant from the start to the completion of the metering process by storing in the storage part in front of the plunger arranged in and causing the plunger to perform the metering process and the injection filling process. Also, by forming a flight similar to the screw at the plunger tip and making the rotation speed of the plunger larger than the rotation speed of the screw, melting into the gap between the inner peripheral surface of the screw and the outer peripheral surface of the plunger during the measuring process This prevents the back flow of the resin. Furthermore, since plastics (resin material) plasticized by the plasticizing screw is stored in the storage part from the injection nozzle side in the plasticized order, so-called first-in first-out can be performed.

  In Patent Document 2, in an injection molding apparatus (injection molding machine) provided with a screw type plasticizing apparatus (injection apparatus) formed by enclosing a screw in a heating cylinder, the screw is formed in a hollow shape, and the screw A plunger that can move in the axial direction with respect to the screw is inserted therein, and a space formed by the relative movement of the screw and the plunger is used as a chamber portion (reserving portion) for storing molten and plasticized resin. An injection molding apparatus is disclosed.

  In the plasticizing device (injection device) of the injection molding device of Patent Document 2, the screw is dedicated to the plasticizing step, and in the screw, the plunger arranged coaxially with the screw performs the measuring step and the injection filling step. This is the same as the injection device of Patent Document 1. The difference from the injection device of Patent Document 1 is that this screw is configured to slightly move backward and forward, and the resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw by the backward movement. The communication resin flow path is formed between the front and the reservoir in front of the plunger, and the communication resin flow path is sealed by the advance. From the start to the completion of the metering process, the connecting resin flow path is in the retracted position so as to form and maintain the plasticizing flow length is not changed by the backward and forward movement of the screw. However, because of its configuration, the melted and plasticized resin is stored from the plunger front end surface side of the storage portion at the start of the metering step, and stored at the injection nozzle side at the time of completion, so that first-in first-out cannot be performed.

  Here, as in Patent Document 1 and Patent Document 2, an injection device in which a plunger is arranged coaxially with the screw in the screw, the screw is dedicated to the plasticizing process, and the plunger performs the metering process and the injection filling process. In this specification, it shall be called an inline-type plunger type injection device.

JP-A-10-337754 Japanese Patent Laid-Open No. 61-084221

  In the in-line plunger type injection device of Patent Document 1, the screw groove depth (the height in the radial direction of the flight portion from the outer peripheral surface of the injection plunger) is shallow on the premise of high-speed rotation of the injection plunger, and the injection plunger Since the screw (flight) portion of the tip is filled with the plasticized molten resin, when the injection plunger moves forward in the injection filling process, the back flow of the molten resin stored in front of the injection plunger ( There are few backflows). That is, there is no mechanical check valve mechanism that prevents the back flow of the molten resin during the injection filling process. Here, in the injection filling process, there are two portions where the back flow of the molten resin should be prevented. One place is a communication resin flow path that connects a resin flow path formed between the inner peripheral surface of the plasticizing cylinder and the outer peripheral surface of the plasticizing screw and a storage portion in front of the injection plunger, and the other place is a plastic flow path. This is a gap between the inner peripheral surface of the plastic screw and the outer peripheral surface of the injection plunger.

  However, if the high speed rotation of the injection plunger prevents the backflow of the molten resin during the weighing process to the gap between the inner peripheral surface of the plasticizing screw and the outer peripheral surface of the injection plunger, The molten resin is filled only in the tip portion (front) of the screw (flight) portion formed at the tip portion of the injection plunger. That is, at the tip of the injection plunger filled with the molten resin, which should act as a sealing mechanism for preventing the back flow of the molten resin to the two places (the communication resin flow path and the gap) during the injection filling process. The length is not sufficiently secured, and a sufficient backflow preventing effect as a sealing mechanism cannot be expected. Further, since the injection plunger is not rotated during the injection filling process, the effect of preventing the backflow due to the high-speed rotation of the injection plunger cannot be expected. Therefore, in the injection filling process, a back flow of the molten resin to the communication resin flow path and the gap occurs, and thus the problem that the injection amount varies is not solved.

  In the inline-type plunger injection device of Patent Document 2, the screw is moved backward during the metering process to form a communication resin flow path between the resin flow path and the reservoir, and the screw is advanced during injection filling. The screw is configured to be movable in the axial direction in order to seal the communication resin flow path and prevent the backflow of the molten resin in the reservoir to the resin flow path. With this configuration, it is possible to reliably prevent the backflow of the molten resin to the resin flow path during the injection filling process. However, although the amount of movement of the screw in the axial direction is small compared to the amount of movement of the plunger that performs the metering process and the injection filling process, the longitudinal axis is separate from the mechanism that moves the plunger in the axial direction. There is a problem that a mechanism for moving the screw rotating in the center further in the axial direction is required, and the configuration of the injection apparatus becomes complicated.

  The present invention has been made in view of the above-described problems. Specifically, the structure is not complicated, and an inline plunger injection that can prevent the backflow of the molten resin in the metering process and the injection filling process. The object is to provide a device.

The above object of the invention is to provide a heating cylinder having an injection nozzle at one end and a material supply at the other end;
In the heating cylinder, a hollow cylindrical screw disposed rotatably about the longitudinal axis;
A plunger arranged in the hollow portion of the screw so as to be rotatable coaxially with the screw and movable in the axial direction;
Flight formed in a predetermined range of the outer peripheral surface of the plunger on the injection nozzle side;
A check ring disposed on the injection nozzle side of the plunger;
A resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw;
In the weighing step, a communication resin flow path that communicates the resin flow path and the outer peripheral surface of the plunger where the flight is formed;
Achieved by an injection device of an injection molding machine.

  That is, in the in-line plunger type injection device, a communication resin flow path is formed in advance between the resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw and the predetermined range of the outer peripheral surface of the plunger. Therefore, unlike the inline-type plunger injection device of Patent Document 2, it is not necessary to retreat the screw to form the communication resin flow path. Further, in the weighing process, the communication resin flow path communicates with the resin flow path and the outer peripheral surface of the plunger on which the flight is formed, and therefore is positioned in front of the flight formed in a predetermined range of the outer peripheral surface of the plunger. The non-return ring is always positioned in front of the connecting resin flow path. Due to the positional relationship between the connecting resin flow path and the check ring, the molten resin stored in front of the check ring during the injection filling process has two locations (the connecting resin flow path and the inner peripheral surface of the screw and the plunger). Back flow to the outer peripheral surface of the outer peripheral surface of each other can be reliably prevented by one check ring positioned in front of each other, and in the injection filling process as in the inline plunger injection device of Patent Document 1, the communication resin There is no possibility of back flow of the molten resin to the flow path and the gap. Therefore, unlike the inline-type plunger injection device of Patent Document 2, it is not necessary to advance the screw and seal the communication resin flow path. As a result, the screw need not be configured to be movable in the axial direction, and the injection device can be simplified.

  Further, in the injection device of the injection molding machine, an end of the screw on the material supply unit side is supported by the heating cylinder, and the communication resin flow path is an inner surface of the heating cylinder on the injection nozzle side. And both ends of the screw on the material supply part side and the injection nozzle side are supported by the heating cylinder, and the communication resin flow path, From the injection nozzle side outer peripheral surface of the screw to the hollow portion of the screw, the screw may be constituted by at least one communicating hole that penetrates the screw in the radial direction.

  In the former case, since the communication resin flow path is formed as a space between the front inner surface of the heating cylinder and the screw end surface, it is necessary to separately process a similar communication resin flow path or the like inside the heating cylinder or screw. Absent. In the latter case, it is necessary to process a communication hole that penetrates the screw in the radial direction from the front outer peripheral surface of the screw to the hollow portion. However, with this configuration, the front of the screw can be supported by the heating cylinder, both ends of the screw are supported by the heating cylinder, and the screw support structure can be simplified relative to the cantilever support structure of the screw. It is possible to accurately and stably rotate the screw.

An injection apparatus for an injection molding machine according to the present invention includes a heating cylinder having an injection nozzle at one end and a material supply unit at the other end,
In the heating cylinder, a hollow cylindrical screw disposed rotatably about the longitudinal axis;
A plunger arranged in the hollow portion of the screw so as to be rotatable coaxially with the screw and movable in the axial direction;
Flight formed in a predetermined range of the outer peripheral surface of the plunger on the injection nozzle side;
A check ring disposed on the injection nozzle side of the plunger;
A resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw;
In the weighing step, a communication resin flow path that communicates the resin flow path and the outer peripheral surface of the plunger where the flight is formed;
Therefore, the structure is not complicated, and an inline plunger injection device that can prevent the backflow of the molten resin in the metering step and the injection filling step can be obtained.

It is a schematic sectional drawing which shows the injection apparatus of the injection molding machine which concerns on Example 1 of this invention. It is a schematic sectional drawing which shows the injection apparatus of the injection molding machine which concerns on Example 2 of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 do not show the configuration of an injection molding machine other than an injection device, its fixed plate, a fixed mold, a movable mold, and the like for ease of explanation. For the same reason, hatching indicating a cross section is omitted for the heating means and screw described later even for a cross section. In addition, the Example described below does not limit the embodiment of the injection apparatus of the injection molding machine according to the present invention, and the injection apparatus of the injection molding machine according to the present invention is described in the claims. It can be implemented in various ways within the range.

  A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view showing an injection apparatus of an injection molding machine according to Embodiment 1 of the present invention.

  First, the basic configuration of the injection apparatus 1 of the injection molding machine according to the first embodiment of the present invention will be described. On the back side of the fixed platen of the mold clamping device of the injection molding machine (not shown), the fixed platen is arranged so as to be dockable to the fixed die attached to the front side of the fixed platen (surface facing the movable platen). The injection device 1 is in a state where the weighing process is completed. The injection device 1 includes a heating cylinder 15 having an injection nozzle 13 at an end (not shown) on the stationary platen side (left side in the drawing) and a material supply unit 14 at the other end (right side in the drawing), A hollow cylindrical screw 16 rotatably disposed about the longitudinal axis, a plunger 17 disposed in a hollow portion of the screw 16 so as to be rotatable coaxially with the screw 16 and movable in the axial direction; A flight 17a formed in a predetermined range of the outer peripheral surface of the plunger 17 on the injection nozzle 13 side, a check ring 18 disposed on the injection nozzle 13 side of the plunger 17, an inner peripheral surface of the heating cylinder 15 and the screw 16 The resin flow path 10 formed between the outer peripheral surface and the communication resin flow path communicating the resin flow path 10 and the outer peripheral surface of the plunger 17 on which the flight 17a is formed in the weighing step. It includes 1, a. And since this connection resin flow path 11 connects the resin flow path 10 and the outer peripheral surface of the plunger 17 in which the flight 17a is formed, it is ahead of the flight 17a formed in the predetermined range of the outer peripheral surface of the plunger 17. The check ring 18 positioned at is always positioned in front of the connecting resin flow path 11. Here, in order to simplify the explanation, the injection nozzle 13 side (left side of the drawing) of the heating cylinder 15 is “front” of the injection apparatus 1, and the material supply unit 14 side (right side of the drawing) is “rear”. As described above, the movement of the resin material or the like in each direction is referred to as “advance” and “retreat”.

  Next, details of each basic configuration will be described. A heating means 15 a such as an electric heater is arranged on the outer peripheral surface of the heating cylinder 15 so as to be wound around the heating cylinder 15. Further, the material supply unit 14 above the rear outer peripheral surface of the heating cylinder 15 is generally a material supply hopper whose upper part can be opened widely, and a resin in the hopper is provided by a level sensor or the like disposed in the hopper. While monitoring the amount of material, the resin material is often supplied in batches from the outside. However, depending on the type of resin material to be used and the like, a material supply device may be attached upstream thereof, or material supply means such as a material supply pipe may be directly connected.

  In the measuring step, the communication resin flow path 11 that communicates the resin flow path 10 and the outer peripheral surface of the plunger 17 on which the flight 17 a is formed is formed between the inner surface of the heating cylinder 15 on the injection nozzle 13 side and the front end face of the screw 16. It is formed as a space between. Further, in a predetermined range of the outer peripheral surface of the plunger 17 on the injection nozzle 13 side, it is possible to prevent the backflow of the molten resin into the gap between the inner peripheral surface of the screw 16 and the outer peripheral surface of the plunger 17 during the measuring step. The main purpose flight 17a is formed. Here, a gap between the inner peripheral surface of the screw 16 and the outer peripheral surface of the plunger 17 is defined as a gap 19.

  In a general in-line plunger type injection device, a predetermined gap (gap 19) is provided between the inner peripheral surface of the screw 16 and the outer peripheral surface of the plunger 17 for sliding the plunger 17 in the longitudinal axis direction. I need. In order to minimize the gap 19 in order to prevent the backflow of the molten resin, a seal mechanism is arranged in view of problems such as an increase in sliding resistance in the longitudinal axis direction of the plunger 17 and abnormal wear of the contact surfaces with each other. It is necessary to process the inner peripheral surface of the screw 16 and a part of the outer peripheral surface of the plunger 17 with very high processing accuracy. Therefore, instead of minimizing the gap 19, a predetermined amount is secured, and by forming the flight 17a in the predetermined range on the outer peripheral surface in front of the plunger 17, such as the flight 16a of the screw 16 described later, If the plunger 17 is rotated during the metering step to prevent the molten resin from flowing back into the gap 19 from the resin flow path 11, high processing accuracy and the like on the seal mechanism and related members become unnecessary. The shape and size of the flight 17a is such that the molten resin is prevented from flowing back during the measurement process and flows from the resin flow path 11 to a predetermined range on the outer peripheral surface in front of the plunger 17 from the start to the completion of the measurement process. It is sufficient that the molten resin is designed to have a specification for the purpose of causing the molten resin to flow to the storage unit 20 described later in front of the plunger. There is no need to form. However, as will be described later, at the injection filling completion position of the plunger 17, the flight 17 a may be formed to the rear (from the plunger 17 side end portion of the resin flow path 11) to a range that makes at least one round (one pitch). preferable. Further, the structure for preventing the backflow of the molten resin in the gap 19 during the measurement process by the rotation of the flight 17a is different from the sealing mechanism or the like, and the melt stored in front of the check ring 18 in the measurement process. In addition to the pressure control (back pressure control) of the molten resin when the plunger 17 moves backward, the specification for assisting the compression of the molten resin by the flight 16a of the screw 16 is taken into consideration so that the pressure of the resin becomes appropriate. You can also. On the other hand, in the flight 17a of the plunger 17, it is not necessary to consider the plasticization of the resin material.

  Further, on the outer peripheral surface of the screw 16, a flight 16 a is formed in which a resin material such as a resin pellet supplied from the material supply unit 14 flows forward by rotating the screw 16 in the resin flow path 10. Is done. The shape and size of the flight 16a are such that the resin material supplied from the material supply unit 14 is in a plasticized state (molten state) suitable for measurement in the resin flow path 10 until it reaches the check ring 18. Designed to specification. Further, the screw 16 can be arbitrarily set via a rotational drive transmission mechanism 16c such as a ring gear arranged on the rear outer peripheral surface of the screw 16 protruding from the rear of the heating cylinder 15 by a screw rotation driving means 16b such as an electric motor. It can be rotated at an arbitrary rotational force.

  On the other hand, the plunger 17 arranged in the hollow portion of the screw 16 is also similar to the screw 16, such as a gear arranged on the rear outer peripheral surface projected from the rear of the screw 16 by the plunger rotation driving means 17b such as an electric motor. The plunger 17 can be rotated at an arbitrary speed and an arbitrary rotational force via the rotational drive transmission mechanism 17c. Furthermore, the plunger 17 can be moved at an arbitrary speed and an arbitrary moving force in the longitudinal axis direction of the screw 16 by a plunger driving means 17d that combines a hydraulic cylinder, an electric motor, a ball screw, and the like. In this embodiment, the plunger driving means 17d is premised on a configuration in which an electric motor 17e and a ball screw 17f are combined. Here, in the measuring step, the space in front of the check ring 18 in which the plunger 17 is retracted by the resin pressure of the plasticized molten resin and the molten resin is stored is defined as a storage portion 20.

  The check ring 18 arranged on the injection nozzle 13 side of the plunger 17 is arranged in front of the screw of the injection device of a general injection molding machine as described above. The resin pressure (resin flow path 11) and the check ring (return ring 18) are opened in front of the reservoir (reservoir 20) in the resin pressure. Even if it is the general structure which seals between the storage part (storage part 20) ahead of the resin flow path (connection resin flow path 11) and the non-return ring (return ring 18) by the resin pressure of the molten resin acting on good. Furthermore, a configuration is disclosed in which the check ring can be opened and sealed in each step mechanically and forcibly using the rotational operation of the screw (for example, the present applicant has filed an application). Such as a non-return ring, such as JP-A-7-214619 or JP-A-2008-254359, which is a person, may be employed.

  Next, an injection molding method using the injection apparatus of the injection molding machine according to the first embodiment of the present invention will be described with reference to FIG. Here, FIG. 1 shows a state in which the plunger 17 reaches the weighing process completion position and the weighing process is completed, and is referred to in order to facilitate understanding of the following explanation. It does not indicate the states to be described sequentially. Also, the arrows in the figure indicate the direction of action such as general movement, rotation, pressure, etc. of the resin material and each component to facilitate the understanding of the following explanation, regardless of the completion of the weighing process. It is shown.

  After the measuring step is completed, the rotation of the screw 16 by the screw rotation drive means 16b and the rotation drive transmission mechanism 16c is stopped. Thereafter, the rotation of the plunger 17 by the plunger rotation drive means 17b and the rotation drive transmission mechanism 17c is also stopped. In order to prevent the backflow of the molten resin to the gap 19, it is preferable to stop the rotation of the screw 16 and the plunger 17 in this order. At this time, the injection nozzle 13 is closed by the injection nozzle 13 or a resin shut-off switching valve disposed at a resin inlet of a fixed mold (not shown) to which the injection nozzle 13 is docked (× Mark).

  After the rotation of the screw 16 and the plunger 17 is stopped, the plunger 17 is advanced at an arbitrary speed and an arbitrary moving force by the plunger driving means 17d. At this time, the injection nozzle 13 is opened at an appropriate timing. Then, the resin pressure generated in the molten resin in the reservoir 20 by the advancement of the plunger 17 causes the check ring 18 to retreat, thereby preventing the molten resin from flowing back to the connecting resin flow path 11 and the gap 19 behind the check ring 18. At the same time, the molten resin in the storage unit 20 is injected and filled into the mold cavity formed in the fixed mold and the movable mold (not shown) in which the injection nozzle 13 is docked via the injection nozzle 13 (injection filling step). ).

  After the injection filling process is completed, the plunger 17 is rotated by the plunger rotation drive means 17b and the rotation drive transmission mechanism 17c. Thereafter, when the screw 16 is rotated by the screw rotation driving means 16b and the rotation drive transmission mechanism 16c, the resin material supplied from the resin supply unit 14 is heated while flowing forward in the resin flow path 10 by the flight 16a. The molten state is generated by the heat energy of the shear heat generated by the rotational force of the means 15a and the flight 16a, and the front side of the plunger 17 at the injection filling completion position 17 ′ (two-dot chain line in FIG. 1) passes through the connecting resin flow path 11. It flows on the outer peripheral surface of the. Subsequently, the molten resin has a gap 19 ′ formed between the inner peripheral surface in front of the heating cylinder 15 and the outer peripheral surface in front of the plunger 17 by a flight 17 a formed in a predetermined range on the outer peripheral surface in front of the plunger 17. (Refer to FIG. 3) is flowed forward and reaches the check ring 18. The resin pressure of the molten resin advances the check ring 18 to open the gap 19 ′ and the storage portion 20, and the molten resin continues to the storage portion 20 in front of the molten resin via the check ring 18. Stored (metering process).

  Since the plunger 17 is at the injection filling completion position 17 ′ at the start of the weighing process, the flight 17a formed on the outer peripheral surface of the plunger 17 on the injection nozzle 13 side passes through the communication resin flow path 11 at the start of the weighing process. In order to cause the molten resin flowing on the outer peripheral surface of the plunger 17 to flow further forward, at the injection filling completion position 17 ′ of the plunger 17, behind the end on the plunger 17 side of the communication resin flow path 11, It is preferable to form up to at least one round (one pitch) (see FIG. 3).

  At this time, since the injection nozzle 13 is in a closed state (x mark), the resin pressure of the molten resin that has flowed into the reservoir 20 also acts on the plunger 17. As a result, the entire plunger 17 starts to retract by receiving a force in the retracting direction. The molten resin is continuously stored in the storage portion 20 formed in conjunction with the retreat. Until the storage portion 20 is expanded and a predetermined amount of molten resin is stored, the rotation of the screw 16 and the plunger 17 and the backward movement of the plunger 17 are continued, and the open state of the check ring 18 is maintained (metering step). ). In addition, the molten resin that has flowed to the storage unit 20 at the start of the weighing process is stored from the injection nozzle 13 side of the storage unit 20. Since the molten resin is stored while retracting the plunger 17 as the metering process proceeds, the molten resin can be stored at the tip of the plunger 17 of the storing part when the metering process is completed, and the molten resin can be first-in / first-out.

  As described so far, the molten resin does not enter the gap 19 due to the rotation of the flight 17a of the plunger 17 during the backward movement of the plunger 17 in this measuring step. Further, when the plunger 17 is retracted, a force in the forward direction toward the plunger 17 may be applied by the plunger driving means 17d in order to apply a predetermined resistance force (back pressure) to the retracting operation. It is also possible to control the resin pressure of the molten resin in the storage unit 20 by controlling the resistance force to the backward movement in this way together with the rotational force and rotational speed of the screw 16. Further, as described above, the control of the resin pressure of the molten resin in the reservoir 20 may be assisted by the rotation operation of the flight 17a of the plunger 17. If it is confirmed by a position detection function (not shown) of the plunger 17 that a predetermined amount of molten resin has been stored in the storage unit 20, the rotation operation of the screw 16 by the screw rotation drive means 16b and the rotation drive transmission mechanism 16c, The rotation operation of the plunger 17 by the plunger rotation drive means 17b and the rotation drive transmission mechanism 17c is stopped, and the metering process is completed. After the completion of the weighing process, the process proceeds to the injection filling process described above.

  After the injection filling process is completed, in the injection molding machine (not shown), the molten resin injected and filled into the mold cavity formed between the fixed mold and the movable mold is cooled and solidified by the mold clamping operation of the mold clamping device. Until the mold is clamped. Then, after the cooling and solidification time has elapsed, the movable mold is opened from the fixed mold by the mold clamping device, and the cooled and solidified resin molded product is conveyed out of the mold from the mold cavity by the product take-out means or the like. . Subsequently, the movable mold is closed to the fixed mold by the mold clamping device, and a mold cavity is formed again between the fixed mold and the movable mold, and the preparation for the next injection filling process is completed. In the meantime, in the injection device 1, after the injection filling process is completed, the weighing process may be completed in accordance with the timing of the next injection filling process.

  Next, Embodiment 2 of the present invention will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view showing an injection apparatus of an injection molding machine according to Embodiment 2 of the present invention, and shows a state in which the weighing process is completed as in FIG. 2 of Embodiment 1.

  The difference in the basic configuration between the injection device 2 of the second embodiment and the injection device 1 of the first embodiment is that both ends of the screw are supported by the heating cylinder, and the connecting resin flow path is from the front outer peripheral surface of the screw. It is the point comprised by the communicating hole which penetrates a screw to a hollow part. Since the basic configuration other than these is the same as the individual basic configuration described in the first embodiment, the description thereof will be omitted. In FIG. Only differences from Example 1 will be described. Further, the injection molding method using the injection device 2 of the injection molding machine according to the second embodiment of the present invention is basically the same as that of the first embodiment, and therefore the description thereof is omitted.

  Both ends of the screw 26 are supported by the heating cylinder 15. Specifically, the screw 26 has a front end projecting as a hollow rotating shaft, and is rotatably supported in front of the heating cylinder 15 via a rotation support means such as a bearing (not shown). . Although not shown, a configuration may be adopted in which the front inner side of the heating cylinder 15 is projected in accordance with the inner diameter of the hollow portion of the screw 26 to serve as a rotating shaft of the screw 26.

  On the other hand, the flight 16a is continuously formed on the outer circumferential surface of the screw 26, or the screw 26 is disposed on the rear outer circumferential surface of the screw 26 that protrudes from the rear of the heating cylinder 15 by a screw rotation driving means 16b such as an electric motor. The screw 26 can be rotated at an arbitrary speed and an arbitrary rotational force via the rotational drive transmission mechanism 16c such as a ring gear.

  A communication hole 21 that penetrates the screw 26 in the radial direction is formed from the front outer peripheral surface of the screw 26 to its hollow portion. This communication hole 21 is an alternative to the communication resin flow path 11 in the first embodiment. As described above, the communication resin flow path is not formed in the space between the front inner surface of the heating cylinder and the end portion of the screw but by the communication hole arranged in the radial direction of the screw, so that the communication hole 21 is formed in the screw 26. Need to be processed. However, by this, the front of the screw 26 can also be supported by the heating cylinder 15, and both ends of the screw 26 are supported by the heating cylinder 15, with respect to the cantilever support structure of the screw 16 as in the first embodiment. The support structure of the screw 26 can be simplified, and the rotational operation of the screw 26 can be accurately and stabilized.

  Here, as for the quantity, arrangement, shape, and the like of the communication hole 21, an optimal one may be adopted as appropriate according to the specifications of the injection device. For example, even if the communication hole 21 is formed perpendicularly to the radial direction from the outer peripheral surface of the screw 26 to the center of the hollow portion, the flow direction of the resin material in the resin flow path 10 of the screw 26 is the circle on the outer peripheral surface of the screw 16. In consideration of the circumferential direction, it may be formed so as to be inclined by a predetermined angle or curved.

  As described above, the injection device of the injection molding machine according to the present invention is not complicated in structure, and can prevent the backflow of the molten resin in the metering process and the injection filling process. On the other hand, the injection device of the injection molding machine according to the present invention has a configuration in which a plunger is disposed coaxially with the longitudinal axis in the hollow portion of the screw, so that the screw outer diameter is outside the screw of a general in-line screw type injection device. It must be larger than the diameter, and similarly the outer diameter of the heating cylinder must be larger. However, if the screw outer diameter is increased, the total length of the screw can be shortened even if the same plasticizing flow length is secured. Moreover, since the inside of a screw and the inside of a heating cylinder are hollow, even if the outer diameter of a screw becomes large, those weights do not increase in proportion. Furthermore, the fact that the overall length of the screw can be shortened can also shorten the overall length of the heating cylinder and the plunger, and the overall length of the injection device can also be shortened. As a result, not only can the load of the screw support structure supporting the cantilever rotation like the injection device 1 of the first embodiment be reduced, but also the processing and production of each part such as the heating cylinder, screw, plunger, etc. that constitute the injection device. -Needless to say, assembly and maintenance have great advantages. If the both ends of a screw are supported by a heating cylinder like the injection device 2 of Example 2, these merit will become larger.

DESCRIPTION OF SYMBOLS 1 Injection apparatus 2 Injection apparatus (Example 2)
DESCRIPTION OF SYMBOLS 10 Resin flow path 11 Connection resin flow path 13 Injection nozzle 14 Material supply part 15 Heating cylinder 16 Screw 17 Plunger 17a Flight (plunger)
18 Check ring 21 Communication hole (second resin flow path / Example 2)
26 Screw (Example 2)

Claims (3)

A heating cylinder having an injection nozzle at one end and a material supply at the other end;
In the heating cylinder, a hollow cylindrical screw disposed rotatably about the longitudinal axis;
A plunger arranged in the hollow portion of the screw so as to be rotatable coaxially with the screw and movable in the axial direction;
Flight formed in a predetermined range of the outer peripheral surface of the plunger on the injection nozzle side;
A check ring disposed on the injection nozzle side of the plunger;
A resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw;
In the weighing step, a communication resin flow path that communicates the resin flow path and the outer peripheral surface of the plunger where the flight is formed;
An injection device for an injection molding machine.   The end of the screw on the material supply unit side is supported by the heating cylinder, and the communication resin flow path is formed between the inner surface of the heating cylinder on the injection nozzle side and the end surface of the screw. The injection apparatus for an injection molding machine according to claim 1.   Both ends of the screw on the material supply part side and the injection nozzle side are supported by the heating cylinder, and the communication resin flow path extends from the injection nozzle side outer peripheral surface of the screw to the hollow part of the screw. The injection device for an injection molding machine according to claim 1, wherein the injection device is constituted by at least one communicating hole penetrating the screw in the radial direction.

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