JP2014073621A - Injection unit of injection molding machine and injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-line-type and plunger-type injection unit in which the structure is not complicated, failure resin due to long term retention is not generated and the whole length is not long, and an injection molding method using the in-line-type and plunger-type injection unit.SOLUTION: An injection unit of an injection molding machine comprises: a heating cylinder; a hollow and cylindrical screw arranged rotatably in the center of the longitudinal axis of the heating cylinder inside the heating cylinder; a first resin flow passage formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw; a second resin flow passage formed between the injection-nozzle-side inner surface of the heating cylinder and the end surface of the screw; a plunger arranged in the same axis of the screw and movably in the direction of the axis inside the hollow section of the screw; a check ring arranged between the first resin flow passage and the second resin flow passage; and a seal structure which is arranged at the injection nozzle side of the plunger and is positioned at a position protruding by a specified amount from the end surface of the screw when the plunger is at the injection filling completion position.

Description

  The present invention relates to an injection apparatus and an injection molding method for use in 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 (molten resin) moves the check ring forward by the resin pressure resulting from the flow, opens the resin flow path, and passes through the groove portion of the screw head to be an injection nozzle. And between the screw heads. 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, in an injection molding apparatus provided with a screw type plasticizing device (injection device) formed by enclosing a screw in a heating cylinder, the screw is formed in a hollow shape, and the screw is placed inside the screw. On the other hand, an injection molding apparatus is disclosed in which a plunger movable in the axial direction is inserted, and a space formed by relative movement of the screw and the plunger is used as a chamber part for storing molten and plasticized resin.

  That is, the plasticizing apparatus (injection apparatus) of the injection molding apparatus of Patent Document 1 uses a screw exclusively for the plasticizing process, and causes a plunger disposed coaxially with the screw to perform a measuring process and an injection filling process in the screw. Thus, the plasticizing flow length is made constant from the start to the completion of the metering process. Here, the screw forms a communication resin flow path 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 storage portion, and seals the communication resin flow path. Therefore, it is configured to move backward and forward slightly, but from the start to the end of the weighing process, it is in the retracted position to form and maintain the connecting resin flow path. The plasticization flow length does not change due to retreat and advance.

In Patent Document 2, a hollow cylindrical screw is disposed in a heating cylinder having an injection nozzle at the tip so as to be rotatable and relatively movable with respect to the heating cylinder, and in the hollow portion of the screw, A plunger is inserted into the screw so as to be relatively movable in the axial direction thereof, and is provided so as to be able to protrude from the tip of the screw. The resin material supplied into the heating cylinder is used to rotate the screw. It is plasticized and melted while being sent forward by operation, and is stored in the front part in the heating cylinder, while the stored molten resin material is injected from the injection nozzle by relative movement of the plunger with respect to the screw. I made an injection device like
A storage chamber (reservoir) having an inner diameter smaller than the inner diameter of the screw placement portion of the heating cylinder is disposed at a front portion in the heating cylinder, and the distal end portion of the plunger is moved relative to the screw by the relative movement. Provided with a size capable of entering while forming a gap with the inner peripheral surface of the chamber, and in a state where the plunger tip enters the storage chamber, the screw is rotated in front of the heating cylinder. The sent molten resin material is configured to be introduced and stored in the storage chamber through the first gap between the outer peripheral surface of the plunger tip and the inner peripheral surface of the storage chamber. An injection device is disclosed.

  In the injection device of Patent Document 2, the screw is exclusively used for the plasticizing process, and a plunger arranged coaxially with the screw in the screw is used for the metering process and the injection filling process, and the communication between the resin flow path and the storage unit. It is the same as the injection device of Patent Document 1 in that the screw is slightly retracted and advanced for forming and sealing the resin flow path. However, the space that becomes the storage portion is not formed inside the screw, but is formed in front of the screw in the heating cylinder in advance, and the plunger that protrudes from the screw front end and advances to the space that becomes the storage portion, It differs from the injection device of Patent Document 1 in that the molten resin is stored by retreating to the screw front end by the resin pressure. That is, unlike the injection device of Patent Document 1, the molten resin is not stored in the screw. Due to this difference, the molten resin first plasticized at the start of metering is stored from the front (injection nozzle side) of the reservoir, and the last plasticized plastic at the end of metering is behind the reservoir (plunger side). In other words, the so-called first-in first-out can be performed.

  On the other hand, in the plasticizing device (injection device) of the injection molding device disclosed in Patent Document 1, since the storage portion is formed in front of the hollow portion of the screw (inside the screw), the molten resin first plasticized at the start of measurement is The molten resin stored from the rear (plunger side) of the storage unit and plasticized last when the measurement is completed is stored in the front (injection nozzle side) of the storage unit, and the first-in first-out is not performed. . As described above, when the first-in first-out of the molten resin stored in the storage unit cannot be performed, the molten resin stays in front of the plunger (tip surface) in the heating cylinder after injection filling, and as a result, the start of the metering process of the molding cycle. In some cases, the staying resin having the longest thermal history in the molding cycle is not injected. Such a staying resin is not injected during the metering step of the next molding cycle or during a plurality of molding cycles, and is continuously heated, so it deteriorates or carbonizes and is injected. It becomes a defective resin unsuitable for filling. In the injection filling process of the repeated molding cycle, the defective resin generated in this way is injected at irregular timing into the molten resin in the reservoir, and is injected, resulting in poor appearance and insufficient strength of the resin molded product. It is said that product defects such as

  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.

Japanese Patent Laid-Open No. 61-084221 JP 2001-030318 A

  In the inline plunger type injection device of Patent Document 1 and Patent Document 2, a communication resin flow path is formed between the resin flow path and the reservoir during the metering process, and the communication resin flow path is sealed during injection filling. The screw is configured to be movable in the axial direction in order to prevent the molten resin in the storage part from flowing back into the resin flow path. The amount of movement is small compared to the amount of movement of the plunger that performs the metering step and the injection filling step, but apart from the mechanism that moves the plunger in the axial direction, a screw that rotates about the longitudinal axis is further added. There is a problem that a mechanism for moving in the axial direction is required, and the configuration of the injection apparatus becomes complicated.

  In addition, in the inline-type plunger type injection device of Patent Document 1, defective resin that stays for a long time in front of the plunger (tip surface) in the heating cylinder is mixed into the molten resin in the storage portion, resulting in poor appearance and strength of the resin molded product. There is a problem that product defects such as shortage occur.

  Furthermore, in the inline-type plunger-type injection device of Patent Document 2, although the generation of defective resin due to long-term residence can be prevented by first-in first-out of the molten resin in the storage part, the space serving as the storage part is not inside the screw but heated. Since it is formed in advance ahead of the screw in the cylinder, there is a problem that the entire length of the heating cylinder and the entire length of the plunger become long.

  The present invention has been made in view of the above-described problems. Specifically, the in-line plunger injection device does not have a complicated structure, does not generate defective resin due to long-term residence, and does not increase the overall length. And an injection molding method using the in-line type plunger type injection 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 first resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw;
A second resin flow path formed between an inner surface of the heating cylinder on the injection nozzle side and an end surface of the screw;
A plunger arranged in the hollow portion of the screw coaxially with the screw and movably in the axial direction;
A check ring disposed between the first resin flow path and the second resin flow path;
Position that is arranged on the injection nozzle side of the plunger and seals between the inner peripheral surface of the hollow portion of the screw and the outer peripheral surface of the plunger, and protrudes a predetermined amount from the screw end surface at the injection filling completion position of the plunger A sealing mechanism
Achieved by an injection device of an injection molding machine.

  That is, in the in-line type plunger type injection device, during the metering step, the hollow portion of the screw serving as the molten resin storage portion and the first resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw. A second resin flow path (communication resin flow path) is previously formed between the first resin flow path and the second resin flow path, and the first resin flow path of the molten resin in the injection filling process is provided between the first resin flow path and the second resin flow path. Since the non-return ring for preventing backflow is provided, it is not necessary to move the screw in the axial direction as in the inline plunger type injection device of Patent Document 1 and Patent Document 2. As a result, the injection device can be simplified.

  In addition, since the seal mechanism arranged on the plunger injection nozzle side protrudes a predetermined amount from the screw end surface at the plunger injection filling completion position, the molten resin in the hollow portion of the screw is completely discharged in this injection filling process. And the molten resin does not stay in the hollow portion of the screw. Further, the molten resin in the second resin flow channel staying between the seal mechanism and the check ring in the position protruding by the predetermined amount is opened from the first resin flow channel at the start of the metering step of the next molding cycle. This is pushed into the newly plasticized molten resin flowing into the second resin flow path through the non-return ring, and is reliably stored and injected into the hollow portion of the screw serving as the storage portion. The molten resin stays in the two resin flow paths for a long time over a plurality of molding cycles, and no defective resin is generated.

  In addition, since the molten resin flows through the second resin flow path in front of the hollow portion of the screw, the molten resin needs to be stored in front of the hollow portion of the screw, and a space for this needs to be arranged in advance in front of the screw. And the total length of the injection device does not increase.

  In the injection device of this injection molding machine, the check ring opens the space between the first resin flow path and the second resin flow path by rotating the screw in the rotation direction during plasticization, or The structure may be such that the first resin flow path and the second resin flow path are sealed by rotating in the direction opposite to the rotation direction during plasticization.

Further, by using the injection device of this injection molding machine, the resin material supplied from the material supply part of the heating cylinder is plasticized and plasticized in the first resin flow path by the rotation of the screw. The molten resin is caused to flow to the injection nozzle side of the screw via the second resin flow path, and the plunger is moved to the material supply unit side by the resin pressure, so that the hollow portion of the screw is A plasticizing and metering process for storing on the injection nozzle side;
After completion of the plasticizing and metering step, the plunger is moved to the injection nozzle side, the molten resin stored on the injection nozzle side of the hollow portion of the screw is injected from the injection nozzle, and the injection filling of the plunger is performed. An injection filling step in which the sealing mechanism is at a position protruding a predetermined amount from the screw end surface at a completion position;
It is preferable to perform an injection molding method characterized by having

  Further, in the injection molding method using the injection apparatus of the injection molding machine, at the start of the plasticizing and metering step, the screw is rotated in the rotational direction at the time of plasticization, and the first resin flow is caused by the check ring. After the plasticization measurement preparation step for opening the path and the second resin flow path, or after the plasticization measurement step is completed, the screw is rotated in the direction opposite to the rotation direction during plasticization, and the check ring is used. An injection preparation step for sealing between the first resin flow path and the second resin flow path may be further provided.

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 first resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw;
A second resin flow path formed between an inner surface of the heating cylinder on the injection nozzle side and an end surface of the screw;
A plunger arranged in the hollow portion of the screw coaxially with the screw and movably in the axial direction;
A check ring disposed between the first resin flow path and the second resin flow path;
A position that is disposed on the injection nozzle side of the plunger and seals between the inner peripheral surface of the hollow portion of the screw and the outer peripheral surface of the plunger, and projects a predetermined amount from the screw end surface at the injection filling completion position of the plunger A sealing mechanism
Therefore, the structure is not complicated, a defective resin due to long-term residence is not generated, and the in-line type plunger injection device in which the total length does not become long can be obtained.

In the injection molding method according to the present invention, the resin material supplied from the material supply part of the heating cylinder is plasticized in the first resin flow path by the rotation of the screw, and the plasticized molten resin is used. To the injection nozzle side of the screw via the second resin flow path, and the plunger is moved to the material supply unit side by the resin pressure, and the injection nozzle side of the hollow portion of the screw Plasticizing and weighing process to be stored in
After completion of the plasticizing and metering step, the plunger is moved to the injection nozzle side, the molten resin stored on the injection nozzle side of the hollow portion of the screw is injected from the injection nozzle, and the injection filling of the plunger is performed. An injection filling step in which the sealing mechanism is at a position protruding a predetermined amount from the screw end surface at a completion position;
Therefore, it is preferable to use the injection device of the injection molding machine according to the present invention.

FIG. 3 is a schematic cross-sectional view showing a state after completion of an injection filling process of an injection device of an injection molding machine according to Example 1 of the present invention. It is a schematic sectional drawing which concerns on Example 1 of this invention and shows the plasticization measurement process of the injection apparatus of an injection molding machine. It is a schematic sectional drawing which concerns on Example 1 of this invention and shows the injection preparation process of the injection apparatus of an injection molding machine. It is a schematic sectional drawing which concerns on Example 1 of this invention and shows the injection filling process of the injection apparatus of an injection molding machine.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing the first embodiment of the present invention after completion of an injection filling process of an injection device of an injection molding machine. FIG. 2 is a schematic cross-sectional view illustrating a plasticizing and metering process of an injection device of an injection molding machine according to the first embodiment of the present invention. FIG. 3 is a schematic cross-sectional view illustrating an injection preparation process of an injection apparatus of an injection molding machine according to the first embodiment of the present invention. FIG. 4 is a schematic sectional view showing an injection filling process of an injection apparatus of an injection molding machine according to the first embodiment of the present invention. In addition, this Example 1 does not limit this invention to described embodiment, It cannot be overemphasized that it can implement with the various form within a claim.

  First, the basic configuration of an injection apparatus 1 of an injection molding machine according to the present invention will be described with reference to FIG. Here, FIG. 1 to FIG. 4 illustrate the configuration of an injection molding machine other than the injection apparatus 1 and its fixed plate, fixed mold, and movable mold in order to facilitate understanding of each process to be described. Not. For the same reason, hatching indicating a cross section is omitted in the heating means 5a, the flight 6a, the rotation drive transmission mechanism 6c, the check ring 8 and the like, which will be described later, even in the cross section.

  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 an injection filling process described later has been completed. The injection device 1 includes a heating cylinder 5 having an injection nozzle 3 at an end portion (not shown) on the stationary platen side (left side in the drawing) and a material supply unit 4 at the other end portion (right side in the drawing), A hollow cylindrical screw 6 rotatably disposed about the longitudinal axis, a first resin flow path 10 formed between the inner peripheral surface of the heating cylinder 5 and the outer peripheral surface of the screw 6, and the heating cylinder 5 The second resin flow path 11 formed between the inner surface on the injection nozzle 3 side and the end surface of the screw 6 is disposed coaxially with the screw 6 in the hollow portion of the screw 6 so as to be movable in the axial direction. The plunger 7, the check ring 8 disposed between the first resin flow path 10 and the second resin flow path 11, the injection nozzle 3 side of the plunger 7, the inner peripheral surface of the hollow portion of the screw 6, and the plunger 7. And seal between the outer peripheral surfaces of the In the injection filling completion position, provided with a sealing mechanism 9 consisting of the screw 6 the end surface with a predetermined amount alpha (alpha) protruding position. In order to simplify the description, the injection nozzle 3 side (left side of the drawing) of the heating cylinder 5 is “front” of the injection device 1 and the material supply unit 4 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 5 a such as an electric heater is arranged on the outer peripheral surface of the heating cylinder 5 so as to be wound around the heating cylinder 5. In addition, the material supply unit 4 above the rear outer peripheral surface of the heating cylinder 5 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.

  Further, on the outer peripheral surface of the screw 6, a flight 6 a for causing the resin material such as the resin pellet supplied from the material supply unit 4 to flow forward by rotating the screw 6 in the first resin flow path 10 is continuous. Formed. The shape and size of the flight 6 a are in a plasticized state (molten state) suitable for measurement in the first resin flow path 10 until the resin material supplied from the material supply unit 4 reaches the check ring 8. It is designed to such a specification. In addition, the screw rotation drive means 6b such as an electric motor is used to drive the screw 6 inside the heating cylinder 5 via a rotation drive transmission mechanism 6c such as a ring gear disposed on the rear outer peripheral surface of the screw 6 protruding from the rear of the heating cylinder 5. The screw 6 can be rotated at an arbitrary speed and an arbitrary rotational force.

  On the other hand, the plunger 7 disposed in the hollow portion of the screw 6 is moved at an arbitrary speed and an arbitrary moving force in the longitudinal axis direction of the screw 6 by a plunger driving means 7a combining a hydraulic cylinder, an electric motor, a ball screw, and the like. It can be moved with. In this embodiment, the plunger driving means 7a is premised on a configuration in which an electric motor 7b and a ball screw 7c are combined. Here, in the plasticizing and metering step to be described later, the space in front of the hollow portion of the screw 6 in which the plunger 7 moves backward due to the resin pressure of the plasticized molten resin and the molten resin is stored is defined as a storage portion 20.

  Further, the non-return ring 8 disposed between the first resin flow path 10 and the second resin flow path 11, specifically, the front outer peripheral surface of the screw 6 is a general injection molding as described above. In the plasticizing metering process, the resin flow path and the screw head of the screw are opened by the resin pressure of the molten resin. In the injection filling process to be described later, The general structure which seals between the resin flow path and the screw head of the screw by the resin pressure of the molten resin acting in the opposite direction may be used. However, in the case of a check ring having such a general configuration, the resin flow state in each process uses the resin pressure of the molten resin to operate, and the flow state of these resins is unstable. In such a case, the operation timing may vary. Here, 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, by the applicant of the present invention). It is more preferable for the present invention that such a configuration is employed for the operation of the check ring more surely, such as the applicants of JP-A-7-214619 and JP-A-2008-254359. Therefore, in this embodiment, the check ring 8 mechanically and forcibly opens the first resin flow path 10 and the second resin flow path 11 by the rotation of the screw 6 in the plasticizing and weighing step. After the plasticizing and metering step, the space between the first resin flow path 10 and the second resin flow path 11 is sealed by rotating the screw in the direction opposite to the rotation direction during plasticization. Further, the second resin flow path 11 is illustrated to be orthogonal to the first resin flow path 10 for the sake of simplicity, but the injection is performed in order to make the resin flow to the injection nozzle 3 smooth. You may comprise so that it may incline smoothly to the nozzle 3. FIG.

  The plunger 7 arranged in the hollow portion of the screw 6 is retracted in the hollow portion of the screw 6 by the resin pressure of the molten resin in the plasticizing and metering step, and the plunger 6 is hollowed by the plunger driving means 7a in the injection filling step. The molten resin stored in the front part (storage part 20) moves forward in order to inject from the injection nozzle 3. Therefore, both the movement (sliding) of the plunger 7 in the longitudinal axis direction in the hollow portion of the screw 6 and the prevention of intrusion of the molten resin into the rear of the hollow portion of the screw 6 other than the storage portion 20 in these steps. In order to make it possible, a seal mechanism 9 is provided for sealing between the inner peripheral surface of the hollow portion of the screw 6 and the outer peripheral surface of the plunger 7. In order to simplify the drawing, the gap is drawn between the inner peripheral surface of the hollow portion of the screw 6 and the outer peripheral surface of the seal mechanism 9, but the actual gap is very small. Otherwise, the molten resin does not enter the rear of the hollow portion of the screw 6.

  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 FIGS. FIG. 1 shows a state where the injection filling process is completed as described above. The injection nozzle 3 is in an open state, and the check ring 8 is in a state of sealing between the first resin flow path 10 and the second resin flow path 11. The sealing state (sealing operation) of the check ring 8 is indicated by blackening the corresponding configuration in the drawing. Although not shown in the figure, the resin material (the front is in a molten state and the rear is in an unmelted state) stays in the first resin flow path 10 although not shown. Further, in the space from the second resin flow path 11 to the injection nozzle 3, the molten resin that has not been injected stays. Further, the seal mechanism 8 is in a position protruding from the end face of the screw 6 by a predetermined amount α at this injection filling completion position, and completely injects (discharges) the molten resin in front of the hollow portion (reservoir 20) of the screw 6. ing. The arrows in the figure indicate the direction of the resin material, the movement of each component, and the force and pressure acting on them.

  As shown in FIG. 2, after the injection filling process is completed, when the screw 6 is rotated by the screw rotation drive means 6b and the rotation drive transmission mechanism 6c, the check ring 8 is forcibly opened (plasticization measurement). Preparation step). The operation of the screw rotation drive means 6b and the rotation drive transmission mechanism 6c is indicated by blacking the corresponding configuration in the drawing, and the open state (opening operation) of the check ring 8 is outlined in the corresponding configuration. I will show you that. The screw 6 is rotated, and the resin material supplied from the resin supply unit 4 flows forward in the first resin flow path 10 by the flight 6 a and reaches the check ring 8 disposed on the front outer peripheral surface of the screw 6. In between, it will be in a molten state by the thermal energy of the shearing heat by the rotational force of the heating means 5a and the flight 6a. Further, the unmelted portion of the resin material staying in the first resin flow path 10 in the previous molding cycle is similarly melted and flows to the second resin flow path 11 via the check ring 8. The molten resin remaining in the second resin flow path 11 in the previous molding cycle is pushed out by the newly plasticized molten resin flowing into the second resin flow path 11 through the open check ring 8. Then, the fluid flows forward of the plunger 7. Therefore. Since the molten resin does not stay in the second resin flow path 11 over a plurality of molding cycles and is injected for each molding cycle, no defective resin is generated due to long-term residence.

  At this time, the injection nozzle 3 is in a state of being closed by the injection nozzle 3 or a resin shut-off switching valve disposed at a resin inlet of a fixed mold (not shown) to which the injection nozzle 3 is docked. This is indicated by attaching a cross to the corresponding configuration in the figure. Since the injection nozzle 3 and the check ring 8 are sealed, the resin pressure of the molten resin flowing from the second resin flow path 11 to the front of the plunger 7 also acts on the plunger 7. As a result, the entire plunger 7 receives a backward force and starts to move backward. The molten resin is continuously stored in the space between the injection nozzle 3 in the heating cylinder 5 and the tip of the plunger 7 formed in conjunction with the retreat, that is, in the storage unit 20. Until the storage portion 20 is expanded and a predetermined amount of molten resin is stored, the rotation of the screw 6 and the backward movement of the plunger 7 are continued, and the open state of the check ring 8 is maintained (plasticization measurement step). . As described above, when the plunger 7 is retracted, the sealing mechanism 9 prevents the molten resin from entering the rear of the hollow portion of the screw 6 other than the storage portion 20. Further, when the plunger 7 is retracted, a forward force to the plunger 7 may be applied by the plunger driving means 7a 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 6. If it is confirmed by a position detection function (not shown) of the plunger 7 that a predetermined amount of molten resin has been stored in the storage unit 20, the rotation operation of the screw 6 by the screw rotation drive means 6b and the rotation drive transmission mechanism 6c is stopped. To complete the plasticizing and metering process.

  Next, as shown in FIG. 3, after the plasticizing and metering step is completed, the screw 6 is rotated by a predetermined angle in the direction opposite to the rotational direction at the time of plasticization by the screw rotation drive means 6b and the rotation drive transmission mechanism 6c. The check ring 8 forcibly seals between the first resin flow path 10 and the second resin flow path 11 (injection preparation process). Since the reverse rotation operation of the screw 6 only requires the check ring 8 to perform the sealing operation, the reverse rotation amount (rotation angle) is small, and the resin material in the first resin flow path 10 due to the reverse rotation of the screw 6 is obtained. Backward flow backwards is not a problem. After the sealing operation, the reverse rotation operation of the screw 6 is stopped. Also, during the period from the completion of the plasticizing and metering process to the completion of the injection preparation process, the forward force to the plunger 7 is applied by the plunger driving means 7a to control the resin pressure of the molten resin in the storage section 20. Is preferred.

  In the injection preparation process, after the check ring 8 shifts to the sealed state, as shown in FIG. 4, the plunger drive means 7a advances the plunger 7 at an arbitrary speed and an arbitrary moving force (injection filling process). The operation of the plunger driving means 7a (the electric motor 7b and the ball screw 7c) is indicated by blackening the corresponding configuration in the drawing. At this time, the injection nozzle 3 is opened at an appropriate timing. Further, since the check ring 8 is kept in the sealed state from the injection preparation step, first, the molten resin staying in the space from the second resin flow path 11 to the injection nozzle 3 in the previous molding cycle is injected. It is injected from the nozzle 3 and the molten resin in the reservoir 20 is also injected continuously. In this state, the plunger 7 is moved forward to the injection filling completion position, the seal mechanism 9 of the plunger 7 becomes a position protruding a predetermined amount α from the end face of the screw 6, and the injection filling process is completed, resulting in the state shown in FIG. At the injection filling completion position of the plunger 7, the sealing mechanism 9 is in a position protruding a predetermined amount α from the end surface of the screw 6, thereby completely injecting (discharging) the molten resin in front of the hollow portion (reservoir 20) of the screw 6. ) What you can do is as described above.

  As described above, the steps from FIG. 1 to FIG. 4 are the plasticization measurement preparation step, plasticization measurement step, injection preparation step, and injection filling step of the injection apparatus 1 of the injection molding machine according to Embodiment 1 of the present invention. On the other hand, after the injection filling process in the injection apparatus 1 is completed, in an injection molding machine (not shown), the mold cavity formed between the fixed mold and the movable mold is injection filled by the mold clamping operation of the mold clamping apparatus. The mold clamping state is maintained until the molten resin is cooled and solidified. 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 apparatus 1, after the injection filling process is completed, the plasticization measurement preparation process, the plasticization measurement process, and the injection preparation process described above may be completed in accordance with the timing of the next injection filling process.

  Here, the screw of a general in-line screw type injection device is retracted in the longitudinal axis direction from the start to the completion of the weighing process, while the position of the material supply unit does not change, so the plasticizing flow length is Although it has been explained that it becomes shorter in proportion to the amount of retraction of the screw and causes problems such as a decrease in plasticizing ability and a variation in the plasticized state of the resin material, the problem due to the retraction of the screw is not limited thereto. Another problem is that the bulk density of the resin material supplied from the material supply unit to the resin flow path on the outer periphery of the screw during the injection filling process is in the plasticizing process (metering process). In this case, the bulk density of the same portion of the resin material supplied is reduced, and the bulk density itself becomes unequal.

  Specifically, during the plasticizing process (measuring process), the resin material that has fallen onto the resin flow path in the outer periphery of the screw directly under the material supply unit due to gravity is forced to rotate the entire screw outer periphery due to the rotation of the screw (flight). The resin flow path formed in is flowed forward of the screw. At this time, while the screw is rotating, it is slowly retracted due to the resin pressure of the molten resin previously stored in the storage portion in front of the screw. Due to such a supply state of the resin material, the bulk density of the resin material in the resin flow path in the peripheral part of the screw in the vicinity immediately below the material supply part is substantially constant during the plasticizing process (metering process) and becomes uneven. There is no.

  However, during the injection filling process, the screw does not rotate and moves forward at a predetermined speed. Therefore, although the resin material that has fallen onto the resin flow path in the outer periphery of the screw directly under the material supply unit due to gravity falls directly below the screw, the resin that is forcibly formed around the outer periphery of the screw by the rotation of the screw (flight) The flow path (especially the side) is not flowed forward of the screw. In addition, the forward speed of the screw at this time is faster than the backward speed of the screw in the plasticizing process (measuring process), and in some cases, it is not constant due to the multistage injection speed setting or the like. Due to such a supply state of the resin material, the bulk density of the resin material in the vicinity immediately below the material supply unit is reduced with respect to the plasticizing process (measurement process). It becomes uneven in the resin flow path on the outer periphery of the screw.

  As a result, in the continuous molding cycle, the bulk density of the supplied resin material is low in the resin flow path of the screw, and an uneven part is generated every time during the injection filling process. While flowing forward, the other bulk density is high, and the same heat energy as that of a certain part is received and plasticized, so that the plasticized state of the molten resin also becomes uneven. On the other hand, the in-line type plunger injection device according to the present invention is such that the screw does not move in the longitudinal axis direction but rotates only in the plasticizing and metering step and the injection filling step. In the resin material, the bulk density of the resin material is low and uneven parts do not occur. In addition to the plasticizing ability and the stabilization of the plasticized state of the resin material by securing a certain plasticizing flow length, the material material is directly under the material supply section. High-quality plasticization is possible by supplying a resin material that makes the bulk density of the resin material in the resin flow path high and constant.

  Furthermore, since the plunger is arranged coaxially with the longitudinal axis in the hollow portion of the screw, the screw outer diameter must be larger than the screw outer diameter of a general in-line screw type injection device, The outer diameter of the heating cylinder must be increased. However, if the screw outer diameter increases, the same plasticizing flow length can be secured even if the screw overall length is shortened. Further, since the inside of the screw and the inside of the heating cylinder are hollow, their weight does not increase proportionally even if the outer diameter increases. In view of the above, 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 be shortened. This not only reduces the load on the support structure of the screw that serves as a cantilever rotation support, it is also extremely large for processing, manufacturing, assembly, and maintenance of each part of the heating cylinder, screw, plunger, etc. that make up the injection device. It goes without saying that there are advantages.

DESCRIPTION OF SYMBOLS 1 Injection apparatus 3 Injection nozzle 4 Material supply part 5 Heating cylinder 6 Screw 7 Plunger 8 Check ring 9 Seal mechanism 10 1st resin flow path 11 2nd resin flow path

Claims (4)

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 first resin flow path formed between the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw;
A second resin flow path formed between an inner surface of the heating cylinder on the injection nozzle side and an end surface of the screw;
A plunger arranged in the hollow portion of the screw coaxially with the screw and movably in the axial direction;
A check ring disposed between the first resin flow path and the second resin flow path;
Position that is arranged on the injection nozzle side of the plunger and seals between the inner peripheral surface of the hollow portion of the screw and the outer peripheral surface of the plunger, and protrudes a predetermined amount from the screw end surface at the injection filling completion position of the plunger A sealing mechanism
An injection apparatus for an injection molding machine.   The non-return ring opens the space between the first resin flow path and the second resin flow path by rotating the screw in the rotation direction during plasticization, or the direction opposite to the rotation direction during plasticization. 2. The injection apparatus for an injection molding machine according to claim 1, wherein the gap between the first resin flow path and the second resin flow path is sealed by rotating the first and second resin flow paths. The rotation of the screw plasticizes the resin material supplied from the material supply unit of the heating cylinder in the first resin flow path, and the plasticized molten resin passes through the second resin flow path. A plasticizing and metering step of causing the plunger to move to the material supply unit side by the resin pressure and storing the screw on the injection nozzle side of the hollow portion of the screw;
After completion of the plasticizing and metering step, the plunger is moved to the injection nozzle side, the molten resin stored on the injection nozzle side of the hollow portion of the screw is injected from the injection nozzle, and the injection filling of the plunger is performed. An injection filling step in which the sealing mechanism is at a position protruding a predetermined amount from the screw end surface at a completion position;
An injection molding method using the injection apparatus of the injection molding machine according to claim 1, wherein   At the start of the plasticizing and metering step, the screw is rotated in the direction of rotation at the time of plasticizing, and the plasticizing and metering preparing step of opening between the first resin channel and the second resin channel by the check ring Alternatively, after the plasticizing and metering step is completed, the screw is rotated in a direction opposite to the rotation direction at the time of plasticization, and the first resin flow path and the second resin flow path are sealed by the check ring. The injection molding method according to claim 3, further comprising an injection preparation step of performing the injection apparatus of the injection molding machine according to claim 2.

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