JP2011116068A - Injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent formation of a gate forming part (gate trace) on the outer surface of a molded body along with supply of molten resin, in an injection molding machine molding, by unscrewing molding, the molded body in which a screw groove is formed on the inner side and decoration such as characters, pictures and graphics may be applied on the outer surface, etc. <P>SOLUTION: A core die part 13 is freely rotatably provided in a fixation die 9 fitted to a fixation die plate 6, and an injection nozzle 2 is arranged to face the back face side of the molded boy 15 having the screw groove 16 molded by the core die part 13. A spline shaft 24 of a ball screw mechanism 23 and a main drive gear 10 provided within the fixation die 9 to transmit drive force to the core die part 13 are interconnected by a socket 25 so that the core die part 13 provided in the fixation die 9 can be driven by the ball screw mechanism 23 provided in a movable die plate 5 to which a movable die 12 is fitted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an injection molding machine manufactured by screw-molding a molded body having a thread groove inside a cap of a container and the like, and in particular, a gate forming portion molded integrally with the molded body has characters, pictures, The present invention relates to an injection molding machine capable of manufacturing a molded body so that the molded body is formed not on the outer surface of the molded body to which decoration such as graphics is applied but on the inner side of the thread groove.

  In an injection molding machine that forms a general molded body that does not have a thread groove and is not used in a conventional manner, a granular thermoplastic resin that is a raw material is fed into the heating cylinder and provided in the heating cylinder. While the resin is melted by the advancing and retracting screw, it is sent to the injection nozzle side of the screw tip, and the molten resin is injected from the injection nozzle provided on the screw tip side into the mold cavity closed in the cavity. After the molten resin is cooled and solidified, the mold is opened, and the molded body that is stuck to the mold with protruding pins or the like is removed from the mold to produce the molded body.

  Such an injection molding machine that molds a molded body such as plastic is roughly composed of a mold clamping unit and an injection unit. In the mold clamping unit, a fixed mold is generally used. And a movable mold, and the movable mold is moved forward and backward with respect to the fixed mold by a mold opening and closing mechanism that enables clamping of the movable mold such as a toggle mechanism or a direct pressure method. The mold is closed and opened when the mold is clamped.

  An injection unit is used when pellets, which are granular resin, are supplied as molten resin to the cavity formed when the mold is closed, and the injection unit is provided with drive means such as a motor as a drive source. Then, the rotational force of the motor is sequentially transmitted through pulleys, belts, etc., and the molten resin is conveyed by rotating the screw in the heating cylinder by a ball screw mechanism that converts the rotational motion into linear motion, and then melted. The resin is injected and filled from the injection nozzle into the mold cavity through a path consisting of a sprue, a runner and a gate.

  By the way, when the molded object to be manufactured is a bottle cap or the like of a container for storing a liquid, a thread groove is usually formed inside thereof. When removing the molded body in which the screw grooves are formed from the mold, for example, a core mold portion (so-called screw top) that forms a helical thread groove is held in a state where the molded body is held so as not to rotate. Rotating and screwing out the molded product stuck to the outside from the core mold part, etc., and screwing molding is performed, and the technology related to such screwing was filed by the same applicant as the present applicant. Patent Document 1 and Patent Document 2 disclosed as conventional techniques. In Patent Document 3, an eject mechanism is provided on the moving platen, and the rotational driving force of the eject rod provided on the eject mechanism is transmitted to the slide core drive mechanism via the connector to drive the slide core of the movable mold. An injection molding machine that performs undercut molding is disclosed.

Japanese Patent No. 3304950 Japanese Patent No. 2649098 Japanese Patent No. 2691639

  However, in the injection molding machine capable of screwing and forming in Patent Document 1, Patent Document 2, and Patent Document 3, none of them is the inside of the molded body in which the thread groove is formed, and the outer surface on the opposite side. Since the molten resin will be supplied from the side, uneven gate marks will be formed on the outer surface of the molded body facing the gate for supplying the molten resin to the cavity where the molded body is molded. . Therefore, when characters and figures are added to the outer surface of the molded body at the time of molding or afterwards, it is necessary to remove the trace so that the trace becomes intrusive or inferior in aesthetics, In the case of performing the removal work, there is a problem that the number of work steps increases, and as a result, the cost increases.

  The present invention has been made in view of the above problems, and a molded body in which a thread groove is formed on the inner side and a decoration such as a character, a picture, or a figure may be provided on the outer surface. To provide an injection molding machine capable of preventing a gate forming portion (gate trace) from being formed on the outer surface of a molded body due to the supply of molten resin in an injection molding machine that is molded by screw-out molding. Objective.

The invention of the injection molding machine according to claim 1
A fixed die plate to which a fixed mold is mounted;
A movable die plate to which a movable mold is mounted;
A mold opening / closing mechanism for moving the movable die plate back and forth in the mold opening / closing direction;
An injection unit for injecting and filling molten resin into a cavity formed of the movable mold and the fixed mold via a path in the fixed mold;
An injection molding machine in which the mold opening / closing mechanism, the movable die plate, the fixed die plate, and the injection unit are disposed in the mold opening / closing direction in this order,
The fixed mold is provided with a core mold part for screw forming so as to be rotatable, and the injection nozzle of the injection unit is disposed on the back side where the thread groove of the molded body formed by the core mold part is formed. When the movable die plate is provided with a rotational drive mechanism that is disposed so as to face and rotationally drives the core mold part using a drive motor as a drive source,
The connecting means for transmitting the driving force of the rotational drive mechanism to the core mold part is detachably provided.

The invention of an injection molding machine according to claim 2 is the invention according to claim 1,
The fixed mold is provided with a plurality of core mold parts, and each of the plurality of core mold parts is provided with a driven gear, and the driven gear is engaged with these driven gears so that the main drive gear can freely rotate to the fixed mold. Provided in
The rotational driving force of the rotational drive mechanism provided on the movable die plate is transmitted in the order of the connecting means, the main driving gear, the driven gear, and the core mold part, and a plurality of core mold parts are simultaneously rotated. Thus, the molded body is screwed in parallel from these core mold parts.

The invention of an injection molding machine according to claim 3 is the invention according to claim 2,
A spline shaft that can be moved forward and backward is provided at the tip of the rotational drive mechanism, and the rotational drive force of the rotational drive mechanism is passed through the spline shaft even when the movable die plate to which the movable mold is attached is moved forward and backward. Is transmitted to the connecting means, and the core mold part can be rotated through the connecting means, the main driving gear, and the driven gear.

The invention of an injection molding machine according to claim 4 is the invention according to claim 3,
The connecting means is a detachable socket having a locking portion at a distal end portion and a proximal end portion, and the distal end portion of the socket is locked to the coupling portion of the main gear, while the other proximal end portion is It is characterized by being locked to the tip of the spline shaft.

  According to the present invention of the injection molding machine, since the injection unit is moved back and forth on the fixed die plate side, there may be a space limitation in arranging various devices in the vicinity thereof. A rotary drive mechanism driven by a drive motor is provided on the movable die plate side, not on the side, and the rotational drive force of this rotary drive mechanism is driven by the connecting means and the main driving gear and the driven gear provided in the fixed mold. The core mold part provided integrally with the gear can be rotated, and the molded body can be screwed off from the core mold part in accordance with the rotation. Further, since the injection nozzle is arranged so as to face the back side of the molded body in which the thread groove formed by the core mold portion is formed, the gate forming portion (gate trace) is formed on the outer surface of the molded body. Rather than being formed on the back side of the thread groove, a concave-convex gate forming portion (gate trace) is formed on the outer surface of the molded body where the thread groove is formed on the inner side used for a bottle cap or the like. As a result, it is possible to omit the removal step of removing the gate forming portion (gate trace) afterwards, thereby improving the production efficiency of a molded product that can be a product.

  Further, as the main driving gear rotates, a plurality of driven gears meshed with the main driving gear are simultaneously rotated, and a plurality of core mold portions provided corresponding to the number can be simultaneously rotated. The molded body can be unscrewed in parallel from the core mold portion and can be screwed out. Therefore, the mass production efficiency of the product can be improved, and the cost of the product can be greatly suppressed.

It is sectional drawing of the injection molding machine which shows the state which closed the metal mold | die. It is sectional drawing of the injection molding machine which shows the state which opened the metal mold | die. It is a schematic block diagram which shows the meshing | engagement of the main drive gear and driven gear which were provided in the fixed metal mold | die. It is a perspective view which shows the state which looked at the molded object shape | molded by screwing from the outer surface side. It is a perspective view which shows the state which looked at the molded object shape | molded by screwing from the back side. It is a perspective view which shows the connection part of a spline shaft, a socket, and a main drive gear.

  Hereinafter, an embodiment as a mode for carrying out the present invention will be described with reference to FIGS. Needless to say, the present invention can be easily applied to configurations other than those described in the embodiments without departing from the spirit of the invention.

  As shown in FIGS. 1 and 2, the injection molding machine 1 comprises an injection unit 3 having an injection nozzle 2 at the tip, a mold opening / closing mechanism 4, a movable die plate 5, a fixed die plate 6 and the like. The mold closing unit 7 includes a mold opening / closing mechanism 4, a movable die plate 5, a fixed die plate 6, and an injection unit 3 in that order in the mold opening / closing direction (left-right direction shown in FIG. 2). .

  A nozzle insertion hole 8 through which the tip of the injection nozzle 2 can be inserted is formed in the fixed die plate 6, and a fixed mold 9 is mounted on one side (a movable mold side described later) of the fixed die plate 6. ing.

  As shown in FIGS. 1 to 3, the stationary mold 9 is provided with a main driving gear 10 and a plurality of (four) driven gears 11 meshed with the main driving gear 10. The driven gear 11 is integrally provided with a core mold portion (so-called screw top) 13 that protrudes toward the movable mold 12 mounted on the movable die plate 5, and is provided on the outer peripheral surface thereof. When a screw-like portion (not shown) for forming a helical thread groove 16 is formed on the inner peripheral surface of the molded body 15 and the main driving gear 10 provided integrally with the connecting portion 14 is rotated, the driven portion is driven. The core mold part 13 is rotated via the gear 11, and the molded body 15 held in a non-rotatable manner by a holding means (not shown) is unscrewed from the core mold part 13 and screwed out. The main driving gear 10 and the driven gear 11 in this embodiment employ helical gears.

  Further, as shown in FIG. 4, the molded body 15 molded by the injection molding machine 1 is provided with decorations such as letters, pictures, figures, etc. on the outer surface side (front side) during molding or after molding. As shown in FIG. 5, the injection nozzle 2 is disposed so as to face the back side of the molded body 15 in which the thread groove 16 is formed inside the core mold portion 13. A gate forming portion (gate trace) 17 is formed on the back side inside the molded body 15 which can be a product.

  Further, the movable die plate 5 to which the movable mold 12 is mounted is advanced and retracted in the mold opening / closing direction by the mold opening / closing mechanism 4 constituted by the toggle link mechanism 18, and the mold is clamped. At this time, the plurality of link arms of the toggle link mechanism 18 extend linearly, so that the movable mold 12 mounted on the movable die plate 5 is firmly clamped against the fixed mold 9 mounted on the fixed die plate 6. Is done.

  The movable die plate 5 is provided with a drive motor 20 such as a servo motor, and a ball screw mechanism 23 as a rotational drive mechanism that is rotationally driven through a timing belt 21 and a pulley 22 using the drive motor 20 as a drive source. Further, a spline shaft 24 shown in FIG. 6 and the like is attached to the tip side of the ball screw mechanism 23 so as to be able to advance and retract.

  Further, the convex portion 26 of the base end portion 25a of the socket 25 serving as the connecting means is locked and fixed to the distal end concave portion 24a of the spline shaft 24 by fixing means (not shown). The connecting portion 14 of the main driving gear 10 described above is locked to the concave portion 27 of 25b by using a prevention pin 19 or the like. Even when the movable die plate 5 to which the movable mold 12 is attached is moved forward and backward as the mold is opened and closed, the rotational driving force of the ball screw mechanism 23 driven by the drive motor 20 as a drive source is used as the spline shaft 24, the socket 25, Transmission is performed in the order of the main driving gear 10 and the driven gear 11, and the core mold part 13 provided integrally with the driven gear 11 can be rotated.

  Next, the operation of the injection molding machine 1 according to an example of the present invention will be described with reference to FIGS. As shown in FIG. 1, when the injection unit 3 is moved forward with the mold closed, the molten resin is injected from the injection nozzle 2 which is inserted into a predetermined position of the nozzle insertion hole 8 and whose tip is in contact with the fixed mold. Is injected into the cavity C via the paths (sprues, runners, gates, etc.) 11a, 13a formed in the fixed mold 9, the driven gear 11, and the core mold part 13. The molten resin is supplied to the cavity C from a position corresponding to the back surface side of 15. Therefore, the position of the gate forming portion (gate trace) 17 is on the back side of the molded body 15 as shown in FIG.

  When the molten resin supplied to the cavity C is cooled and solidified, the movable die plate 5 on which the movable mold 12 is mounted is then retracted by the operation of the toggle link mechanism 18 of the mold opening / closing mechanism 4 and fixed mold. 9, the movable mold 12 is opened.

  Next, the drive motor 20 is driven, and the ball screw mechanism 23 is rotationally driven via the timing belt 21 and the pulley 22 by the driving force. Then, the rotational driving force of the ball screw mechanism 23 is transmitted in the order of the spline shaft 24, the socket 25, the main driving gear 10, and the driven gear 11, and the core mold portion 13 provided integrally with the driven gear 11 is rotated.

  When the core mold portion 13 is rotated, the molded body 15 held by the holding means so as not to rotate is screwed off from the core mold portion 13 according to the rotation (shown in FIG. 2). The left side), the molded body 15 is screw-molded (molded body 15 indicated by a two-dot chain line in FIG. 2). Finally, the molded body 15 is taken out from the core mold part 13 by the take-out device.

  As described above, according to the injection molding machine 1 in the present embodiment, the gate forming portion (including the gate trace) 17 accompanying the supply of the molten resin is formed only on the inner side of the back side of the molded body 15 to be screw-molded. Further, it is possible to prevent the gate forming portion (including the gate trace) 17 from being formed on the outer surface of the molded body 15, and the injection unit 3 is moved back and forth on the fixed die plate 6 side. In order to dispose various devices such as a drive motor, there may be a space limitation. However, a ball screw which is a rotational drive mechanism driven by the drive motor 20 is not the fixed die plate 6 side but the movable die plate 5 side. A mechanism 23 is provided, and the rotational driving force of the ball screw mechanism 23 is obtained by using the main driving gear 10 and the driven gear 11 provided on the fixed mold 9 in addition to the socket 25 serving as a connecting means. Is rotated, the molded body 15 from the core mold part 13 with the rotation can be unscrewed molding is unscrewed.

  Furthermore, since the injection nozzle 2 is disposed so as to face the back side where the thread groove 16 of the molded body 15 formed by the core mold portion 13 is formed, the gate forming portion (gate trace) 17 is As shown in FIG. 5, it can be formed not on the outer surface of the molded body 15 but on the back side of the thread groove 16. Therefore, for example, an uneven gate forming portion (including a gate trace) is formed on the outer surface of the molded body 15 that is required for screw-off molding adopted for a bottle cap or the like, as in the past, and afterwards Since it is not necessary to perform the removal process which removes these useless parts, it is possible to improve the production efficiency of a molded body to be screw-formed.

  Further, as the main driving gear 10 rotates, the plurality of driven gears 11 meshed with the main driving gear 10 are rotated at the same time, and a plurality of core mold portions 13 provided corresponding to the number can be rotated at the same time. The plurality of molded bodies 15 can be screwed out in parallel from the plurality of core mold parts 13 to be screwed out. Therefore, the mass production efficiency of the product can be improved, and the cost of the product can be greatly suppressed.

  Further, the ball screw mechanism 23 provided on the fixed die plate 6 aims to eject a general molded body (molded body on which a screw groove is not formed) originally attached to the mold surface by ejecting it. Even if it is used for the ejecting operation, the mechanism for producing a molded body in which the molding object is screw-molded as in the present application (molded body with a thread groove formed on the back side) Can be used as a screw-free molding for rotating the core mold portion 13 to unscrew the molded body 15, and is excellent in versatility.

  Although one embodiment of the present embodiment has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the gist of the present invention. In this embodiment, the main driving gear 10 and the driven gear 11 employ helical gears. However, if the driving force can be transmitted, a combination of spur gears is applied instead. Various gears may be selected as appropriate.

DESCRIPTION OF SYMBOLS 1 Injection molding machine 2 Injection nozzle 3 Injection unit 4 Mold opening / closing mechanism 5 Movable die plate 6 Fixed die plate 11a, 13a Path | route 9 Fixed mold 10 Main drive gear 11 Driven gear 12 Movable mold 13 Core mold part 14 Connection part 15 Molded body 16 Thread groove 20 Drive motor 23 Ball screw mechanism (rotation drive mechanism)
24 Spline shaft 25 Socket (connecting means)
25a Base end (locking part)
25b Tip (locking part)
C cavity

Claims (4)

A fixed die plate to which a fixed mold is mounted;
A movable die plate to which a movable mold is mounted;
A mold opening / closing mechanism for moving the movable die plate back and forth in the mold opening / closing direction;
An injection unit for injecting and filling molten resin into a cavity formed of the movable mold and the fixed mold via a path in the fixed mold;
An injection molding machine in which the mold opening / closing mechanism, the movable die plate, the fixed die plate, and the injection unit are disposed in the mold opening / closing direction in this order,
The fixed mold is provided with a core mold part for screw forming so as to be rotatable, and the injection nozzle of the injection unit is disposed on the back side where the thread groove of the molded body formed by the core mold part is formed. When the movable die plate is provided with a rotational drive mechanism that is disposed so as to face and rotationally drives the core mold part using a drive motor as a drive source,
An injection molding machine comprising a detachable connecting means for transmitting a driving force of the rotation driving mechanism to the core mold part. The fixed mold is provided with a plurality of core mold parts, and each of the plurality of core mold parts is provided with a driven gear, and the driven gear is engaged with these driven gears so that the main drive gear can freely rotate to the fixed mold. Provided in
The rotational driving force of the rotational drive mechanism provided on the movable die plate is transmitted in the order of the connecting means, the main driving gear, the driven gear, and the core mold part, and a plurality of core mold parts are simultaneously rotated. The injection molding machine according to claim 1, wherein the molded body is screwed in parallel from these core mold parts.   A spline shaft that can be moved forward and backward is provided at the tip of the rotational drive mechanism, and the rotational drive force of the rotational drive mechanism is passed through the spline shaft even when the movable die plate to which the movable mold is attached is moved forward and backward. 3. The injection molding machine according to claim 2, wherein the core mold part can be rotated via the connecting means, the main driving gear, and the driven gear.   The connecting means is a detachable socket having a locking portion at a distal end portion and a proximal end portion, and the distal end portion of the socket is locked to the coupling portion of the main gear, while the other proximal end portion is 4. The injection molding machine according to claim 3, wherein the injection molding machine is engaged with a tip of a spline shaft.

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