JP2010208290A - Manufacturing method of injection molding die and molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To equalize the time required for filling a plurality of cavities with a resin. <P>SOLUTION: An injection molding die 10 obtains a plurality of moldings by injecting the resin from an injection opening 21 through four runners 46 to four cavities 50 formed between a fixed template 13 and a movable template 26, wherein the injection molding die 10 is equipped with the fixed template 13, the movable template 26 arranged detachably countering it and a movable piece 48 which is arranged on the movable template 26 to engage on the juncture of the injection opening 21 and four runners 46 and capable of freely altering a channel volume from the juncture to four runners 46. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an injection mold for obtaining a plurality of molded products by injecting resin into a plurality of cavities and a method for manufacturing the molded products.

  When forming multiple cavities in a mold and performing multi-cavity injection molding, if there is variation in the processing accuracy of each runner shape communicating with multiple cavities, the filling time of the molten resin into each cavity during molding There will be a difference. Then, a difference occurs in the temperature of the resin flowing into each cavity, and the filling balance is lost, causing the quality variation of the molded product.

  In order to solve this, for example, Patent Document 1 discloses a technique in which a plurality of nozzle openings for injecting resin are arranged in a branched manner. Thereby, when many pieces are taken, it is possible to perform molding without variation between a plurality of cavities.

JP 2000-313033 A

  However, in Patent Document 1, when there is processing variation in the hole diameter of the nozzle port, or when clogging of foreign matter or the like occurs in the nozzle port, flow resistance is generated in the resin in inverse proportion to the channel area. For this reason, a difference occurs in the amount of resin flowing into each cavity, a difference occurs in the filling time, and the filling balance is lost.

On the other hand, for example, if a valve is provided for each flow path, the structure of the mold becomes complicated. This increases the size of the mold and the manufacturing cost.
The present invention has been made to solve such a problem, and an object of the present invention is to provide an injection mold and a method of manufacturing a molded product that can equalize the filling time of resin into a plurality of cavities. And

In order to solve the above problems, the injection mold according to the present invention is:
A first mold;
A second mold disposed opposite the first mold;
A resin supply unit that injects resin from an injection port and supplies the resin to a plurality of cavities formed between the first mold and the second mold through a plurality of resin flow paths;
A flow rate control member that is disposed in the second mold facing the confluence of the injection port and the plurality of resin flow paths, and that can change the flow volume from the confluence to the plurality of resin flow paths, It is characterized by having.

Further, in the injection mold according to the present invention, in the above injection mold,
The flow rate control member may be a center pin.
Moreover, in the injection mold according to the present invention, in the injection mold, the resin supply unit is
With hot runners,
A discharge nozzle that is connected to the injection port of the hot runner and discharges the resin evenly into the plurality of resin flow paths.

In addition, the method for producing a molded product according to the present invention includes:
A resin supply step of injecting the resin from the injection port and supplying the resin to the plurality of cavities formed between the first mold and the second mold disposed opposite to each other through the plurality of resin flow paths; And
In the resin supply step, a flow volume from the junction to the plurality of resin channels is moved by moving a flow rate control member disposed so as to face the junction between the injection port and the plurality of resin channels. Are controlled to be equal to each other.

  According to the present invention, it is possible to make the filling time of the resin into the plurality of cavities uniform. Thereby, the quality of a molded article can be stabilized.

3 is a cross-sectional view of the injection mold according to Embodiment 1. FIG. It is a principal part expanded sectional view same as the above. 6 is a partial cross-sectional view of a molding die for injection molding according to Embodiment 2. FIG. It is an IV-IV arrow line view same as the above. It is a principal part enlarged plan view same as the above. 6 is a partial cross-sectional view of a molding die for injection molding according to Embodiment 3. FIG. It is a VII-VII arrow line view same as the above.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a cross-sectional view of a mold 10 for injection molding, and FIG. 2 is an enlarged cross-sectional view of the main part thereof.

  In FIG. 1, an injection mold 10 includes a fixed mold 11 and a movable mold 12 that are opposed to each other across a parting line PL. As the injection mold 10, for example, a mold can be used.

  In the present embodiment, the flow volume connected to the plurality of cavities 50 in the multi-cavity can be controlled to control the flow rate of the molten resin to each cavity 50 so as to balance the filling time. It is a thing.

The movable mold 12 is disposed so as to be able to contact and separate in the mold opening / closing direction (left and right direction in FIG. 1) with respect to the fixed mold 11.
The fixed-side mold 11 has a fixed-side mold plate 13 as a first mold and a fixed-side mounting plate 15. The fixed side mounting plate 15 is integrally fixed to the side of the fixed side mold plate 13 opposite to the parting line PL (the side opposite to the movable side mold 12). The fixed side mounting plate 15 is fixed to a fixed side platen of a mold closing device (not shown).

  Although not shown, a fixed-side heating unit for heating the fixed-side template 13 is provided on the outer periphery or inside of the fixed-side template 13. This fixed-side heating unit may have a built-in heater or the like, or may be provided with a temperature control pipe for flowing a temperature control medium such as water or oil. Moreover, what formed the temperature control flow path for flowing a temperature control medium in the stationary side template 13 may be used.

  The fixed side mold plate 13 is provided with a guide pin (not shown) for positioning with the movable side mold 12. This guide pin is fitted into a guide bush (not shown) of the movable mold 12 described later.

  A sprue 20 is provided at the center position of the fixed side mounting plate 15 (concentric with the mold center axis OO). In this embodiment, the sprue 20 is a resin supply part. Molten resin is injected into the inlet of the sprue 20 from the nozzle 24 of the injection molding apparatus. The injected resin is supplied and filled from the injection port 21 at the tip of the sprue 20 to a plurality of cavities 50 described later. Further, a plurality of (four in this embodiment) through-holes 16 are formed symmetrically about the mold center axis OO of the cross section of the sprue 20 in the fixed-side template 13.

Here, the cross section of the sprue 20 refers to a cross section in a direction orthogonal to the mold center axis OO.
An elongated columnar fixed side insert 18 is fitted into the through hole 16.
A cavity 50 is formed between the distal end side (parting line PL side) of the fixed side insert 18 and the distal end side (parting line PL side) of a movable side insert 38 described later.

Next, the movable-side mold 12 includes a movable-side mold plate 26 as a second mold, a plate-shaped heat insulating plate 30, an annular spacer block 31, and a movable-side mounting plate 28.
The movable side mold plate 26 is disposed so as to face the fixed side mold plate 13 described above with the parting line PL interposed therebetween. The movable side mounting plate 28 is fixed to the side of the movable side plate 26 opposite to the parting line PL (the side opposite to the fixed side mold 11). The movable side mounting plate 28 is fixed to a movable side platen of a mold closing device (not shown).

A movable side heating unit for heating the movable side mold plate 26 is provided on the outer periphery or inside of the movable side mold plate 26.
This movable side heating unit may include a built-in heater or the like, or may be provided with a temperature control pipe for flowing a temperature control medium such as water or oil. Further, a temperature control flow path for allowing the temperature control medium to flow through the movable side mold plate 26 may be formed.

  Further, a center hole 32 is formed through the movable side mold plate 26 and the heat insulating plate 30 in the mold center (concentric with the mold center axis OO). In the present embodiment, the center hole 32 is formed as a stepped hole. That is, a resin reservoir 44 is formed on the tip side (parting line PL side) of the center hole 32. A center pin 36 is slidably inserted into the center hole 32.

  The movable mold 12 is provided with a guide bush (not shown) for positioning with the fixed mold 11. The guide pins of the fixed-side mold 11 are fitted into this guide bush, and the fixed-side mold 11 and the movable-side mold 12 are positioned (positioning in the direction orthogonal to the mold center axis OO).

  A plurality (four in the present embodiment) of through-holes 34 are formed symmetrically about the mold center axis OO in the movable side mold plate 26. An elongated columnar movable side insert 38 is slidably inserted into the through hole 34.

  Thus, a plurality (four in this embodiment) of cavities 50 are formed between the distal end side (parting line PL side) of the movable side insert 38 and the distal end side (parting line PL side) of the fixed insert 18. Has been.

  In addition, a disc-shaped protruding plate 40 is accommodated in the inner space of the spacer block 31. The center plate 36 and one end side of the movable side insert 38 (the movable side mounting plate 28 side) are integrally fixed to the protruding plate 40. At the time of mold opening, the protruding plate 40 projects and moves in the mold opening direction (right direction in FIG. 1) by a drive mechanism (not shown).

  In the movable side mold plate 26, a resin reservoir 44 is formed at the center on the parting line PL side. The resin reservoir 44 communicates with the sprue 20 when the mold is closed. Cold slag formed by solidifying a so-called resin stays in the resin reservoir 44.

  Furthermore, a plurality of (four in this embodiment) runners 46 extending radially around the resin reservoir 44 and a gate 47 are formed in a direction perpendicular to the mold center axis OO. The sprue 20, the runner 46, and the gate 47 form a resin injection path into the cavity 50.

  Here, in the present embodiment, the movable side mold plate 26 is arranged facing the confluence of the injection port 21 at the tip of the sprue 20 and the four runners 46, and flows from the confluence to the four runners 46. It is characterized by having a movable piece 48 as a flow rate control member that can change the path volume. In the present embodiment, the movable piece 48 is attached to the tip side (parting line PL side) of the center pin 36.

  That is, as shown in FIG. 2, the center pin 36 has a hollow cylindrical shape. The center pin 36 is formed with a small-diameter elongated hole 41 and a large-diameter hole 42 communicating with the center pin 36. A flat step surface 43 is formed at the boundary between the hole 41 and the hole 42.

  A movable piece 48 is attached to one end of the center pin 36. The movable piece 48 has a hemispherical convex portion 48a and a flat surface 48b. However, the shape of the convex part 48a is not restricted to this. For example, a cone shape, a pyramid shape, an elliptical shape, or the like may be used.

  A rod-like member 49 extending along the mold center axis OO is integrally fixed to the flat surface 48b of the movable piece 48. On the other end of the rod-like member 49, a screw portion 49a is formed. The diameter of the rod-shaped member 49 is smaller than the diameter of the small-diameter hole 41 formed in the center pin 36.

  In order to attach the movable piece 48 to the center pin 36, the disc-shaped flange 51 is screwed into the threaded portion 49 a of the rod-shaped member 49 with the flange 51 applied to the stepped surface 43 inside the center pin 36. At this time, with the flat surface 48b of the movable piece 48 in contact with the end surface 36a of the center pin 36, the rod-like member 49 is moved and adjusted in the hole 41 in the direction perpendicular to the mold center axis OO (arrow A direction). To do.

  In the present embodiment, the case where the rod-shaped member 49 and the flange 51 are screwed together by the screw portion 49a has been described, but the present invention is not limited to this. For example, the rod-shaped member 49 and the flange 51 may be fixed using bolts and nuts, or may be fixed by various adjustable fastening means.

Next, the operation of the present embodiment will be described.
In FIG. 1, the mold is closed by an injection molding machine (not shown) in a state in which the fixed mold 11 and the movable mold 12 arranged opposite to each other are in close contact and the mold is closed.

  In the resin supply process, molten resin is injected from the nozzle 24 of the injection molding machine into the inlet of the sprue 20. Thus, the molten resin is uniformly supplied and filled into the respective cavities 50 from the injection port 21 at the tip of the sprue 20 through the four runners 46 and the gates 47 extending in the direction orthogonal to the mold center axis OO. The

  In the present embodiment, for example, a cycloolefin polymer is used as the resin. Since this cycloolefin polymer does not absorb moisture, it is regarded as a material suitable for optical lenses. However, it is not restricted to this material, For example, you may use a polycarbonate etc.

  In addition, at the time of this resin filling, the fixed side shaping | molding die 11 and the movable side shaping | molding die 12 are heated to predetermined temperature by the fixed side heating unit not shown and the movable side heating unit. This predetermined temperature is a temperature suitable for filling the resin used.

  Here, when there is a processing variation such as surface roughness in the hole diameter of the sprue 20 or when there is a processing variation in the cross-sectional dimension or surface roughness of the runner 46, a difference occurs in the amount of resin flowing into each cavity 50. For this reason, a difference arises in the filling time to each cavity 50. Then, a uniform molded product cannot be obtained.

  Therefore, in FIG. 2, the movable piece 48 arranged facing the junction of the injection port 21 at the tip of the sprue 20 and the plurality of runners 46 is moved and adjusted. In this case, as described above, the position of the movable piece 48 can be arbitrarily adjusted by operating the rod-shaped member 49 and the flange 51. In this adjustment, the movable piece 48 is moved so that the flow path volume of the runner 46 having a large flow path resistance is increased.

  In this way, the flow volume connecting the injection port 21 at the tip of the sprue 20 and the plurality of runners 46 can be changed. Thereby, it can control so that the filling time of molten resin may become equal.

  In the present embodiment, the case where the position adjustment of the movable piece 48 is manually performed has been described. However, the present invention is not limited to this. For example, the movable piece 48 may be movably attached to the end surface 36a of the center pin 36 via a substrate (not shown), and this substrate may be automatically controlled by a drive mechanism (not shown).

  In addition, after the resin is filled, the pressure holding state is maintained at a predetermined pressure with respect to the filled resin. In this way, the resin in each cavity 50 is prevented from sinking. Thus, a highly accurate injection molded product can be obtained.

  Thereafter, the fixed mold 11 and the movable mold 12 are cooled to a predetermined temperature by a fixed heating unit and a movable heating unit (not shown). In this case, when the fixed side heating unit and the movable side heating unit are composed of heaters, the cooling is performed by setting the heating temperature low.

  Next, by a mold opening operation of a mold closing unit (not shown), the movable mold 12 is opened with respect to the fixed mold 11 in the mold opening direction (left direction in FIG. 1) with the parting line PL as a boundary. Next, the protruding plate 40 is moved to protrude toward the parting line PL. Thus, the movable side insert 38 and the like protrude in the same direction, and the molded product is taken out.

According to the present embodiment, it is possible to equalize the filling time of the resin into each cavity 50 in the multi-cavity mold. Thereby, the quality of a molded product can be made uniform.
(Embodiment 2)
3 to 5 are diagrams showing the configuration of the injection mold 10 according to the second embodiment. FIG. 3 is a partial sectional view of the injection mold 10 and FIG. FIG. 5 is an enlarged plan view of a main part thereof.

In addition, the same code | symbol is attached | subjected to the member which is the same as that of Embodiment 1, or is equivalent, and the description is abbreviate | omitted.
In the present embodiment, a plurality of (four in the present embodiment) cavities 50 are formed between the fixed mold 11 and the movable mold 12. Each of these cavities 50 is arranged symmetrically about the mold center axis OO of the sprue 20 and at equal intervals (90 °) in the circumferential direction.

  In addition, guide bushes 39 into which guide pins (not shown) of the fixed mold 11 are fitted are provided at the four corners of the movable mold plate 26. The fixed-side mold 11 and the movable-side mold 12 are positioned with high precision (position in the direction orthogonal to the mold center axis OO) by the guide pins (not shown) and the guide bush 39.

  Further, the movable piece 48 is disposed on the movable side mold plate 26 so that the position of the movable piece 48 can be changed so as to face the junction of the injection port 21 and the four runners 46. The movable piece 48 has a conical or hemispherical convex portion 48a and a flat surface 48b, as in FIG. 2 described above.

The present embodiment is characterized in that a square column spacer 52 is interposed between the flat surface 48b of the movable piece 48 and the end surface 36a of the center pin 36.
The spacer 52 has a square cross section. By adjusting the position of the spacer 52 in the resin reservoir 44, the flow path volume leading to each runner 46 is changed.

  Thus, by combining the movable piece 48 and the spacer 52, the flow path volume is changed according to the difference in flow resistance in the direction of the four runners 46. In this way, the flow path volume from the injection port 21 to the four runners 46 is changed, and the difference in charging time to each cavity 50 is eliminated.

That is, as shown in FIG. 5, the spacer 52 having a square cross section is moved in the direction of each runner 46 (in the directions of arrows A and B) in the resin reservoir 44. Then, gaps g _{1 to} g ₄ between the peripheral wall of the resin reservoir 44 and the corners (corners) of the spacer 52 are finely adjusted. This is because the resin flow rate is easily divided by the square portion of the spacer 52. Thereby, the flow volume from the injection port 21 to the four runners 46 can be accurately changed.

According to the present embodiment, it is possible to equalize the filling time of the resin into each cavity 50 in the multi-cavity mold. As a result, the quality of the molded product can be made uniform.
(Embodiment 3)
6 and 7 are diagrams showing the configuration of the injection mold 10 according to the third embodiment. FIG. 6 is a partial cross-sectional view of the injection mold 10 and FIG. 7 is the VII-VII arrow. FIG.

In addition, the same code | symbol is attached | subjected to the member which is the same as that of Embodiment 1, or is equivalent, and the description is abbreviate | omitted.
The present embodiment is different from the first embodiment in that a hot runner 25 is used instead of the sprue 20 and a fan-shaped discharge nozzle 23 is formed on the parting line PL side of the fixed-side template 13. Yes.

  6 and 7, the fixed-side template 13 has a contact surface 22 formed on the end surface on the parting line PL side. Moreover, the hot runner 25 is inserted along the mold center axis OO of the mold. The tip of the hot runner 25 is in contact with the contact surface 22 of the fixed-side template 13.

  A heating unit 17 is disposed around the hot runner 25. A heater 19 is built in the heating unit 17. The heating unit 17 constantly heats the resin inside the hot runner 25.

  Further, a discharge nozzle 23 divided into four fan shapes is formed on the contact surface 22 located on the end surface of the fixed-side template 13. The discharge nozzle 23 is, for example, a through hole opened in the fixed side template 13. The discharge nozzle 23 is connected to the injection port 25 a of the hot runner 25. In the present embodiment, the hot runner 25 and the discharge nozzle 23 are resin supply units.

  The abutting surface 22 described above has a central disc portion 22 a and a bridge portion 22 b that connects the disc portion 22 a to the fixed-side template 13. Four discharge nozzles 23 are formed between the bridge portion 22b and the bridge portion 22b. The number and shape of the discharge nozzles 23 are not limited to this.

Resin is discharged from the four discharge nozzles 23 toward the four runners 46, respectively.
The discharge nozzle 23 can equalize the amount of resin discharged toward each runner 46. Furthermore, in this case, by changing the position of the movable piece 48 described above and controlling the volume of the flow path communicating with each cavity 50, it is possible to make the filling time of the resin into each cavity 50 uniform. Become.

  According to the present embodiment, as in the second embodiment, it is possible to equalize the filling time of the resin into each cavity 50 in the multi-cavity mold. As a result, the quality of the molded product can be made uniform.

DESCRIPTION OF SYMBOLS 10 Injection mold 11 Fixed side mold 12 Movable side mold 13 Fixed side mold plate 15 Fixed side mounting plate 16 Through hole 17 Heating unit 18 Fixed side insert 19 Heater 20 Sprue 21 Injection port 22 Contact surface 22a Disc Portion 22b Bridge 23 Discharge nozzle 24 Nozzle 25 Hot runner 26 Movable side mold plate 28 Movable side mounting plate 30 Heat insulating plate 31 Spacer block 32 Center hole 34 Through hole 36 Center pin 36a End surface 38 Movable side insert 39 Guide bush 40 Extrusion plate 41 Small-diameter hole 42 Large-diameter hole 43 Step surface 44 Resin pool portion 46 Runner 47 Gate 48 Movable piece 48a Conical convex portion 48b Flat surface 49 Bar-shaped member 49a Screw portion 50 Cavity 51 鍔 52 Spacer

Claims (4)

A first mold;
A second mold disposed opposite the first mold;
A resin supply unit that injects resin from an injection port and supplies the resin to a plurality of cavities formed between the first mold and the second mold through a plurality of resin flow paths;
A flow rate control member that is disposed in the second mold facing the confluence of the injection port and the plurality of resin flow paths, and that can change the flow volume from the confluence to the plurality of resin flow paths, A mold for injection molding, characterized by comprising: In the molding die for injection molding according to claim 1,
The mold for injection molding, wherein the flow rate control member is a center pin. In the injection mold according to claim 1 or 2,
The resin supply unit
With hot runners,
An injection molding die comprising: a discharge nozzle that is connected to an injection port of the hot runner and discharges the resin uniformly into the plurality of resin flow paths. A resin supply step of injecting the resin from the injection port and supplying the resin to the plurality of cavities formed between the first mold and the second mold disposed opposite to each other through the plurality of resin flow paths; And
In the resin supply step, a flow volume from the junction to the plurality of resin channels is moved by moving a flow rate control member disposed so as to face the junction between the injection port and the plurality of resin channels. Are controlled so as to be equal to each other.

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