JP2004209904A - Injection molding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding apparatus using a simple mold capable of being rapidly and simply altered in its cavity shape corresponding to the shape of a molded product and capable of sufficiently satisfying the demand related to the production of a small lot, the shortening of the time limit of delivery and the decrease in cost. <P>SOLUTION: The injection molding apparatus 1 is equipped with the simple mold 2 having a replacing part 14, which has a cavity 20 formed thereto, and the fixing part 15a fixed to a machine main body part 4, and a control part 5 for controlling the opening/closing operation of the simple mold 2. The replacing part 14 has the fixed template 16 fixed to the fixing part 15a, the movable template 17 approaching and separating with respect to the fixed template 16 and an ejector mechanism 18 for ejecting a molded product 25. A hot runner 12 for sending out a molten resin 3 to the cavity 20 in a molten state is formed to the fixing part 15a and a cold runner 21 for guiding the molten resin 3 sent out of the hot runner 12 to the cavity 20 is formed to the fixed template 16. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an injection molding device using a simple mold.
[0002]
[Prior art]
In a general injection molding method, a mold having a cavity corresponding to a product shape is manufactured for each product, and an injection molding process of a molded product is performed. As described above, when the mold is manufactured for each product and the injection molding process is performed, there is a problem that the setup property in the injection molding operation is inferior. Therefore, in recent years, an injection molding method using a simple mold (a so-called cassette mold) has been actively used (see Patent Document 1). By using a cassette type nest that is removable according to the shape of the molded product to be made, the simple mold can change the shape of the cavity more easily and quickly than conventional molds. It was easy to improve the setup in the injection molding operation.
[0003]
[Patent Document 1]
Japanese Patent No. 3261052 FIG. 9 and FIG.
[0004]
[Problems to be solved by the invention]
However, even when using the injection molding method using a simple mold, there is a certain limit in the cavity shape that can be changed by exchanging the nest, and when the cavity shape is complicated, etc. In many cases, a conventional mold was used.
In addition, even when using a simple mold that changes the cavity shape by using a plurality of nests, it is necessary to form a spool, a runner, and a gate in the main mold portion of the mold, respectively. It is difficult to sufficiently satisfy the demands for production, shortened delivery time, and cost reduction.
[0005]
The invention according to the present invention has been made in view of the above problems, and it is possible to quickly and easily change the cavity shape according to the shape of a molded product, and to produce a small lot. It is an object of the present invention to provide an injection molding apparatus using a simple mold capable of sufficiently satisfying demands for shortened delivery time and reduced cost.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a simple mold having a replacement portion in which a cavity is formed and replaced according to the shape of a molded product and a fixing portion fixed to the apparatus main body. And a control unit for controlling the opening and closing operation of the simple mold, wherein the replacement unit is a fixed mold plate held by the fixed unit, a movable mold plate approaching and moving away from the fixed mold plate, A projecting mechanism for separating the molded product from the movable mold plate, and a hot runner for sending the molten resin flowing from the apparatus main body to the cavity in a molten state in the fixed portion. The injection molding apparatus is characterized in that the fixed mold plate is formed with a cold runner for guiding the molten resin delivered from the hot runner to the cavity.
[0007]
According to a second aspect of the present invention, in the injection molding apparatus according to the first aspect, the hot runner includes an open / close valve for sealing the molten resin while keeping the pressure of the molten resin in the cavity and the cold runner. The control unit is provided to open the open / close valve when introducing the molten resin from the hot runner to the cold runner, and after the molten resin is introduced and while the cooling and solidification of the molten resin are performed. Is characterized in that the on-off valve is closed.
[0008]
According to a third aspect of the present invention, in the injection molding apparatus according to the first or second aspect, the control unit controls the temperature of the hot runner and the temperature around the hot runner by controlling the temperature of parts other than the fixed unit. And is performed independently.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an injection molding apparatus according to the present invention will be described with reference to the drawings.
[0010]
1 to 3 are schematic views showing an injection molding apparatus according to the present invention. The injection molding apparatus 1 includes a simple mold 2 for molding a molded article, a main body 4 for injecting a molten resin 3 (hereinafter, referred to as a resin 3) into the simple mold 2, and an injection molding apparatus 1. And a control unit (CPU) 5 for performing control.
[0011]
The main body 4 has a hydraulic motor (not shown), an injection screw 7 that is rotated by the power of the hydraulic motor, an upper cylinder 8 that holds the rotating injection screw 7, and resin 3 injected into the injection screw 7. And a screw cylinder 10 formed at the tip of the main body 4.
[0012]
At the lower end of the hopper 9, an introduction opening 9a for introducing resin into the injection screw 7 is formed, and the resin 3 is guided into the injection screw 7 through this introduction opening 9a. The resin 3 guided into the injection screw 7 is conveyed toward the tip of the main body 4 by the rotation of the injection screw 7 in the cylindrical portion 8. A heater is built in the cylinder upper portion 8, and the heater prevents the resin 3 extruded toward the distal end of the main body 4 from being cooled and solidified by the rotation of the injection screw 7.
[0013]
A band heater is wound around the outside of the screw cylinder 10, and the resin 3 that has been extruded into the screw cylinder 10 with the rotation of the injection screw 7 is maintained in a molten state by the calorific value of the band heater. . The tip of the screw cylinder 10 is provided with a small-diameter nozzle 12 for sending the resin 3 to a holl runner 12 described later. The resin 3 heated by the band heater receives the pressure of the injection screw 7 and the small diameter of the small-diameter nozzle 11. It is pressurized by the formation and injected into the hot runner 12.
[0014]
The simple mold 2 includes an exchange unit 14 in which the cavity 20 is formed and a fixing unit 15 that detachably holds the exchange unit 14. The exchange unit 14 includes a fixed plate 16, a movable plate 17, and a projecting mechanism 18. A concave portion 16a is provided on a parting line surface of the fixed mold plate 16 with the movable mold plate 17, and a convex portion 17a is provided on the movable mold plate 17, which is formed by the concave portion 16a and the convex portion 17a. A cavity 20 is formed by the space.
[0015]
A cold runner 21 is formed on the fixed mold plate 16, and the resin 3 in a molten state flows into the cavity 20 through the cold runner 21. The protruding mechanism 18 is provided with a protruding plate 22 that approaches and separates from the movable mold plate 17. The protruding plate 22 has a return pin 23 for separating the fixed mold plate 16 and the movable mold plate 17 from each other. A spool lock pin 24 for removing the resin cured by the cool runner 21 from the movable mold plate 17 and a protruding pin 25 for removing the molded product 25 from the movable mold plate 17 are provided upright. Further, the movable plate 17 has a return pin insertion hole 17b through which the return pin 23 is inserted, a spool insertion hole 17c through which the spool lock pin 24 is inserted, and a projection pin insertion hole 17d through which the projection pin 25 is inserted. Is provided.
[0016]
The fixed portion 15 includes a first fixed portion 15 a that holds the fixed mold plate 16 and a second fixed portion 15 b that holds the protrusion mechanism 18 and the movable mold plate 17. A hot runner 12 that guides the resin 3 injected from the main body 4 to a cool runner 21 formed on the fixed mold plate 16 is formed in the first fixing portion 15a. The hot runner 12 includes a resin conduction hole 27 for conducting the resin 3, and a hot runner valve 28 for opening and closing the flow path of the resin conduction hole 27. In order to prevent the resin 3 from hardening at the hot runner 12, the inside of the resin conduction hole 27 is maintained at a temperature at which the resin 3 maintains a molten state. The opening and closing of the horranna valve 28 is controlled by the control unit 5.
[0017]
A pair of walls 15e and 15f are formed at the upper and lower ends of the second fixing portion 15b, and a recess 15c is formed at the center of the fixing portion 15b by the wall 15e and the wall 15f. I have. The protruding plate 22 is located in the recess 15c, and the protruding plate 22 moves forward and backward in the recess 15c.
[0018]
Further, the movable mold plate 17 is detachably attached to the end surfaces 15e 'and 15f' of the walls 15e and 15f, and the exchange portion 14 can be detached from the fixed portion 15, so that the cavity 20 is formed. The shape of the cavity 20 can be changed quickly and easily by exchanging the exchange part 14 according to the shape of the molded product 25.
[0019]
The control unit 5 controls the mold opening / clamping of the simple mold 2 and the protrusion control of the protruding pins and the like (FIG. 5A) via an interface unit (I / O) 30 as shown in FIG. In addition to controlling the injection and holding pressure of the resin by operating the hydraulic motor of No. 4, the metering and the like of the resin introduced from the hopper 9 to the injection screw 7 are controlled and controlled (FIG. 5B), and the heat generation of the band heater is controlled. By adjusting the temperature, the temperature of the resin in the screw cylinder 10 is controlled (FIG. 5C), and the opening and closing processing of the hot runner valve 28 is performed (FIG. 5D), and the temperature control of the hot runner 12 and the hot runner 12 periphery (FIGS. 5E and 5F). It is carried out. With this control, automation in the injection molding process is realized and the quality of the molded product is maintained.
[0020]
Next, a production process of a molded article using the injection molding apparatus 1 will be described with reference to a flowchart shown in FIG. The controller 5 moves the protruding plate 22 to clamp the simple mold 2 (step S.1, FIG. 1), and opens the hot runner valve 28 (step S.2). Thereafter, the control unit 5 starts the operation of driving the hydraulic motor to inject the resin 3 (step S.3, FIG. 2), and applies the hot runner 12 of the fixing unit 15a and the cold runner of the movable mold plate 16 to the resin 3. Then, the cavity 20 is filled with the pressure via the pressure holding member 21 to hold the pressure (step S.4). At this time, the control unit 5 controls the temperature control of the hot runner 12 and its peripheral part independently of the temperature control of parts other than the fixing unit 15 so that the injected resin 3 is smoothly filled in the cavity 20. The adjustment is performed so that the resin 3 maintains the molten state.
[0021]
When the cavity 3 is filled with the resin 3 and the pressure holding is completed, the control unit 5 closes the hot runner valve 28 (step S.5, FIG. 3). Then, after the resin 3 is cooled in the cavity 20 (Step S.6) and cured to the shape of the cavity 20, the control unit 5 performs a mold opening process of the simple mold 2, specifically, 2 The fixed portion 15b moves in a direction away from the fixed mold plate 16 while holding the movable mold 17 and the protruding mechanism 18, and the molded product 25 is attached to the movable mold plate 17 while the fixed mold plate 16 and the movable mold The mold is opened with the plate 17 (step S.7). Thereafter, when the projecting plate 22 of the ejecting mechanism 18 moves to the movable mold plate 17 side, the resin 3 cured by the cool runner 21 of the movable mold plate 17 is ejected by the spool lock pin 24 and the molded product 25 is formed. Is protruded from the movable mold plate 17 by the protruding pins 25 (step S.8, FIG. 4). Note that the hot runner valve 28 is closed during this process (steps S.6 to S.8).
[0022]
As described above, since the hot runner valve 28 is closed and the molded product 25 can be cooled while the pressure of the resin filled in the cavity 20 is maintained, the exchange unit 14 can be easily replaced. Even with a simple mold that can be used, it is possible to manufacture a molded product having the same quality as a normal mold.
[0023]
In addition, since the opening and closing control of the hot runner valve 28 and the temperature control of the peripheral portion of the hot runner 12 are performed independently of the temperature state of the portion other than the first fixing portion 15a, the same processing as in a normal mold is performed. The injection molding process can be performed using the process.
[0024]
Furthermore, since the exchange part 14 is detachably installed on the fixed part 15, and the exchangeable exchange part 14 is configured by a simple structure of the fixed plate 16, the movable plate 17, and the protruding mechanism 18, The exchange section 14 forming the cavity 20 can be changed quickly and easily, and small-lot production of the molded article 25, short-term delivery, and low cost can be easily realized.
[0025]
Further, since the hot runner 12 formed in the fixing portion 15 and the cold runner 21 formed in the replacement portion 14 are provided continuously, it is easy to use a side gate, a jump gate, etc. Even the injection molding apparatus 1 using the mold 2 can easily produce a medium-sized or large-sized molded product.
[0026]
As described above, the injection molding apparatus 1 according to the present invention has been described using the embodiments, but the injection molding apparatus 1 according to the present invention is not limited to the above. For example, in the flowchart shown in FIG. 6, the hot runner valve 28 is closed by the control of the control unit 5 when the cavity 20 is filled with the resin 3 and the pressure holding is completed (step S5). The control may be performed such that the hot runner valve 28 is automatically closed after a predetermined time has passed since the hot runner valve 28 was opened. This fixed time can be determined by measuring a general time before the resin is injected and maintaining the pressure by measuring the capacity and the shape of the cavity 20 in advance.
[0027]
【The invention's effect】
As described above, by using the injection molding apparatus according to the present invention, the replacement unit is detachably installed on the fixed unit, and the replaceable replacement unit is called a fixed mold plate, a movable mold plate, or a protrusion mechanism. Since it is configured with a simple structure, the exchange part that forms the cavity can be changed quickly and easily, and it is easy to realize small lot production, short-term delivery, and low cost of molded products. It becomes.
[0028]
In addition, since the hot runner formed in the fixed portion and the cold runner formed in the replacement portion are provided continuously, it is easy to use a side gate or a jump gate, and a simple mold is used. Even an injection molding device can easily mold a medium or large-sized molded product.
[0029]
Furthermore, since the hot runner valve is closed and the molded product can be cooled while maintaining a constant pressure on the resin filled in the cavity, a simple mold including a fixed portion and an exchange portion can be used. Even if it is, it becomes possible to manufacture a molded product of the same quality as a normal mold.
[0030]
In addition, since the temperature control of the hot runner and the peripheral portion of the hot runner can be independently performed regardless of the temperature state and the like other than the fixed portion, the injection molding is performed by using a processing step similar to a normal mold. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an injection molding apparatus according to the present invention, showing a state before a hot runner valve is opened.
FIG. 2 is a schematic view showing an injection molding apparatus according to the present invention, in which a hot runner valve is opened and a hot runner is filled with a molten resin.
FIG. 3 is a schematic view showing an injection molding apparatus according to the present invention, in which a hot runner valve is opened and a cavity is filled with a molten resin.
FIG. 4 is a schematic view showing an injection molding apparatus according to the present invention, and is a view showing a state in which a molded product is being ejected.
FIG. 5 is a block diagram showing control contents of a control unit according to the present invention.
FIG. 6 is a flowchart showing a production process of a molded article in the injection molding apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Injection molding apparatus 2 Simple mold 3 Resin (molten resin)
4 Main unit (device main unit)
5 Control unit 12 Hot runner 14 Replacement unit 15 Fixing unit 15a First fixing unit 15b Second fixing unit 16 Fixed mold plate 17 Movable mold plate 18 Projection mechanism 20 Cavity 21 Cold runner 22 Projection plate 23 Return pin 24 Spool lock pin 25 Protruding pin

Claims (3)

A simple mold having a replacement section in which a cavity is formed and exchanged according to the shape of a molded product and a fixing section fixed to the apparatus main body section, and a control section for controlling the opening and closing operation of the simple mold. Prepare,
The exchange section has a fixed mold plate held by the fixed portion, a movable mold plate approaching and moving away from the fixed mold plate, and a projecting mechanism for separating a molded product from the movable mold plate. ,
In the fixing portion, a hot runner is formed for sending the molten resin flowing from the device main body portion to the cavity in a molten state,
An injection molding apparatus, wherein a cold runner for guiding the molten resin delivered from the hot runner to the cavity is formed on the fixed mold plate. The hot runner is provided with an open / close valve for sealing the molten resin while keeping the pressure of the molten resin in the cavity and the cold runner,
The control unit opens the open / close valve when introducing the molten resin from the hot runner to the cold runner, and after the molten resin is introduced and while the cooling and solidification of the molten resin are being performed, The injection molding apparatus according to claim 1, wherein the on-off valve is closed. 3. The injection molding apparatus according to claim 1, wherein the control unit controls the temperature of the hot runner and the temperature around the hot runner independently of the temperature control of a part other than the fixing unit. 4. .

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