JP2010214765A - Injection molding mold and method of manufacturing molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To charge a plurality of cavities with resin at uniform pressure, and to suppress the cobwebbing of the resin at mold release. <P>SOLUTION: The injection molding mold 10 includes a fixed template 13 and a movable template 26 arranged opposite to the fixed template so as to be freely approachable and separable in the opening/closing direction of the mold, and resin is injected into four cavities 50 formed between the fixed template 13 and the movable template 26 from a tip of a hot runner 20 through four runners 46 to obtain four moldings 54. The mold has a through-hole 14 formed at the fixed template 13 so as to be engaged with the hot runner 20 in a freely slidable way in the opening/closing direction of the mold and an injection inlet 21 formed at the side surface of the tip of the hot runner 20 so as to intersect with the through-hole 14 and face the four runners 46. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an injection mold having an injection port for injecting a molten resin at the tip of a hot runner and a method for producing a molded product.

In the mold for injection molding, in order to use the resin of the cold runner part for the next molding, a hot runner that heats and keeps the resin of that part in a molten state has come to be used.
Normally, this hot runner adopts a pin gate system in which resin is sent from its injection nozzle into a product cavity and the product is separated by mold opening. In this case, if the resin is heated too much in order to improve injection filling, the resin is not solidified by the pin gate, and so-called stringing occurs when the mold is opened. On the other hand, if the resin is not always heated to a predetermined temperature, problems such as clogging occur due to cooling of the resin during injection.

  In such an injection mold, for example, Patent Document 1 discloses a technique of injecting resin from each injection nozzle of a plurality of hot runners and filling a plurality of cavities with the resin through the plurality of runners. Yes. According to this Patent Document 1, it is possible to realize a large number of molded products with high shape accuracy with a single mold.

JP 2004-237727 A

  However, in Patent Document 1, a plurality of hot runners must be provided corresponding to each of the plurality of cavities, which increases the manufacturing cost of the apparatus. In addition, since the temperature of each of the plurality of hot runners is individually controlled, the filling pressure to each cavity varies when a difference occurs in the resin temperature for each hot runner. For this reason, it was difficult to obtain a uniform molded product.

  Furthermore, if the resin temperature is lowered to eliminate the stringing of the resin at the time of mold release, cold slag is generated. Depending on which cavity the cold slag flows into, the resin flow difference occurs and the quality of the molded product varies in each cavity. Could occur.

  The present invention has been made to solve the above-described problems, and is a mold for injection molding capable of filling a plurality of cavities with resin with uniform pressure and suppressing resin stringing at the time of mold release. It aims at providing the manufacturing method of a molded article.

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 hot runner that injects resin from the tip and supplies the plurality of cavities formed between the first mold and the second mold via a plurality of runners;
A through hole formed in the first mold to slidably fit the hot runner in the mold opening and closing direction;
And a resin outlet formed on a side surface of the tip of the hot runner so as to cross the through holes and in the direction of the plurality of runners.

Further, the present invention provides the above injection mold,
It may be provided between the hot runner and the first die, and may have a leading member that applies a biasing force to the hot runner so that the first die can be relatively moved in the die opening and closing direction. is there.

Further, the present invention provides the above injection mold,
The tip of the hot runner on which the resin outlet is formed can be formed in a tapered surface inclined at a predetermined angle with respect to the mold opening / closing direction.

In addition, the method for producing a molded product of the present invention includes:
A resin outlet formed on the side surface of the tip of the hot runner is protruded from a through hole into which the hot runner is inserted in the mold opening / closing direction, and the resin is injected in the runner direction from the resin outlet, Supplying resin through a runner to a cavity formed between a mold and a second mold disposed opposite the first mold;
A cutting step of drawing the resin outlet of the hot runner into the through hole and cutting the resin injected from the resin outlet;
A step of separating the first mold and the second mold in the mold opening direction with a parting line as a boundary after the cutting step;

Further, the present invention provides the above-described method for producing a molded article,
In the cutting step, the hot runner and the parting line can be separated in advance in the mold opening direction by the urging force of the leading member disposed in the first mold.

  INDUSTRIAL APPLICABILITY The present invention can provide a mold for injection molding and a method for manufacturing a molded product that can fill a plurality of cavities with resin with uniform pressure and can suppress stringing of the resin during mold release.

FIG. 3 is a cross-sectional view of the injection mold according to Embodiment 1 (when the mold is closed). It is an arrow view of the II-II direction same as the above. It is sectional drawing of the shaping | molding die for injection molding of the mold opening start. It is a principal part expanded sectional view same as the above. It is sectional drawing of the shaping | molding die for injection molding at the time of a mold opening. It is sectional drawing of the protrusion state of the molded product after mold opening completion. 5 is a cross-sectional view of a main part of a molding die for injection molding according to a second embodiment. FIG. 5 is a cross-sectional view of a main part of a molding die for injection molding according to a second embodiment. FIG. 5 is a cross-sectional view of a main part of a molding die for injection molding according to a second embodiment. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present invention, in order to uniformly inject molten resin into a plurality of cavities, a runner as a plurality of resin flow paths is branched from an injection nozzle of one hot runner, and the pressure loss when the resin branches to each runner And can be molded at a good resin temperature for molding.
[Embodiment 1]
FIG. 1 is a cross-sectional view of a mold 10 for injection molding according to the first embodiment when the mold is closed, and FIG. 2 is an arrow view in the II-II direction.

  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.

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 closely arranged on 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 (not shown) of a mold closing device (not shown). The fixed side template 13 may be divided into a plurality of pieces.

  A fixed-side heating unit (not shown) 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. Further, a temperature control flow path for allowing the temperature control medium to flow inside the fixed side template 13 may be formed.

  Further, the fixed side mold plate 13 is provided with guide pins (not shown) for positioning with the movable side mold 12. The guide pin is fitted into a guide bush 42 of the movable mold 12 described later. In this way, the positioning of the fixed mold 11 and the movable mold 12 (positioning in the direction orthogonal to the mold center axis OO) is performed.

  A locating ring 19 and a hot runner 20 are provided at the center of the fixed side mounting plate 15 (concentric with the mold center axis OO). Molten resin is injected into the inlet 20a of the hot runner 20 from an injection molding apparatus (not shown).

  The hot runner 20 includes a cylindrical cylinder block 22 with a flange with a flange and a heater 23 disposed at the center thereof. Further, four injection ports 21 are formed on the side surface of the tip (parting line PL side) of the cylinder block 22. From these injection ports 21, a plurality of cavities 50 (four in the present embodiment) described later are filled with resin. In addition, a plurality of (four in this embodiment) through-holes 16 are formed symmetrically around the center of the cross section of the hot runner 20 (the mold center axis OO) in the fixed-side template 13. Yes.

Here, the cross section of the hot runner 20 refers to a cross section in a direction orthogonal to the mold center axis OO.
An elongated columnar fixed side insert 18 is inserted into the through hole 16. The fixed side insert 18 is integrally fixed to the fixed side mounting plate 15 with a bolt 17.

A cavity 50 as a molding cavity is formed between the distal end side of the fixed side insert 18 and the distal end side of a movable side insert 38 to be described later.
Next, as shown in FIGS. 1 and 2, the movable mold 12 includes a movable mold 26 as a second mold, a plate-shaped receiving plate 27, an annular spacer block 31, and a movable mold 12. And a side mounting plate 28. The movable side mold plate 26 is disposed opposite to the above-described fixed side mold plate 13 with a parting line (PL) interposed therebetween.

  The receiving plate 27 is disposed in close contact with the movable side mold plate 26, and a space for projecting a molded product is formed by the spacer block 31. 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 (not shown) 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.

  A center hole 32 is formed through the movable mold plate 26 and the receiving plate 27 at the mold center position. The center of the center hole 32 coincides with the mold center axis OO. A center pin 36 is slidably inserted into the center hole 32. In the present embodiment, the four runners 46 and the gate 47 are formed to communicate with each other radially from the center hole 32.

  The movable side mold 12 is provided with guide bushes 42 for positioning with the fixed side mold 11 at four corners. A guide pin (not shown) of the fixed-side mold 11 is fitted into the guide bush 42 so that the fixed-side mold 11 and the movable-side mold 12 are positioned.

  A plurality (four in this embodiment) of through-holes 34 are formed in the movable side mold plate 26 at symmetrical positions about the mold center axis OO and at equal intervals in the circumferential direction. An elongated columnar movable side insert 38 is slidably inserted into the through hole 34. The movable side insert 38 is integrally fixed to the receiving plate 27 with a bolt 29.

  In the present embodiment, the case where four cavities 50 are provided in one mold has been described, but the present invention is not limited to this. For example, two or more cavities 50 may be provided. The number and arrangement of the cavities 50 can be arbitrarily changed as necessary.

As described above, in the present embodiment, the four cavities 50 are arranged symmetrically about the mold center axis OO.
Further, the movable side mold plate 26 and the receiving plate 27 are formed with a small-diameter projecting hole 35 at a position on a line connecting the mold center axis OO and the center of the through hole 34 in plan view. A protrusion pin 39 is inserted into the protrusion hole 35.

  Further, a protruding plate 40 is disposed in the inner space of the spacer block 31. The projecting plate 40 is in contact with one end side (movable side mounting plate 28 side) of the center pin 36 and the projecting pin 39. When the mold is opened, the protruding plate 40 moves forward toward the parting line PL (leftward in FIG. 1) by a drive mechanism (not shown).

  On the parting line PL side of the center pin 36, the front end portion of the hot runner 20 is disposed facing the center pin 36. As described above, the runner 46 and the gate 47 are formed radially from the center pin 36 in a direction perpendicular to the mold opening direction. The hot runner 20, the runner 46, and the gate 47 form a resin injection path into the cavity 50.

  Here, in the present embodiment, a plurality of runners are formed so as to intersect with the through holes 14 formed in the fixed side mold plate 13 so that the hot runner 20 can be slidably inserted in the mold opening / closing direction. An injection port 21 serving as a resin outlet formed on the side surface at the tip of the hot runner 20 is provided in the 46 direction.

  As shown in FIG. 1, the hot runner 20 is integrally fixed by a bolt 24 at the center (mold center axis OO) of the fixed side mounting plate 15. The cylinder block 22 of the hot runner 20 is slidably inserted into the through hole 14 formed in the fixed side template 13.

  Further, the center pin 36 provided in the movable mold 12 is slightly retracted from the movable mold plate 26 at a position facing the hot runner 20. Thereby, a concave portion 37 is formed in the center of the movable side mold plate 26. The tip of the hot runner 20 is configured to enter the recess 37. Thus, in the state where the tip of the hot runner 20 has entered the recess 37, the injection port 21 of the hot runner 20 faces the direction of each runner 46.

  In the present embodiment, a pre-release spring (compression) 52 as a pre-extraction member is mounted between the fixed-side template 13 and the fixed-side mounting plate 15. The leading spring 52 applies an urging force to the fixed side mounting plate 15 so that the fixed side template 13 can be relatively moved in the mold opening and closing direction.

  For this reason, when the mold is opened, the fixed side mold plate 13 and the fixed side mounting plate 15 are separated by a predetermined amount S before the fixed side mold 11 and the movable mold 12 are separated from each other with the parting line PL as a boundary. (See FIG. 3). Thereby, the hot runner 20 moves so as to enter the through hole 14. Thus, the resin injected from the injection port 21 is cut by a shearing force. Therefore, the stringing of the resin at the time of releasing is suppressed.

  In the present embodiment, the case where the pre-release spring (compression) 52 is used as the pre-extraction member has been described. However, the present invention is not limited to this. For example, instead of the pre-spring (compression) 52, rubber or an elastic body may be used.

Next, the operation of the present embodiment will be described with reference to FIGS. 1 and 3 to 6.
In FIG. 1, in the case of injection molding, the stationary mold 11 and the movable mold 12 which are arranged opposite to each other are brought into close contact with each other, and the mold is closed with an injection molding machine (not shown).

  In this state, the fixed side mold 11 and the movable side mold 12 are in close contact with the parting line PL as a boundary. At this time, the injection port 21 of the hot runner 20 faces the direction of each runner 46.

  Next, in the step of filling the molten resin, the molten resin is filled into the inlet 20a of the hot runner 20 from a nozzle of an injection molding machine (not shown). In this way, the molten resin is filled into each cavity 50 from the injection port 21 at the tip of the hot runner 20 through the runner 46 extending in the direction orthogonal to the mold center axis OO and the gate 47.

  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.

In addition, after the resin is filled, the pressure holding state is maintained at a predetermined pressure with respect to the filled resin. As a result, the resin in each cavity 50 is prevented from sinking.
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, FIG. 3 is a cross-sectional view of the injection mold 10 at the start of mold opening, and FIG. 4 is an enlarged cross-sectional view of the main part thereof.
In FIG. 3, when the mold opening operation of a mold closing unit (not shown) is started, the movable mold 12 is slightly moved in the mold opening direction (the direction of arrow A in FIG. 3) relative to the fixed mold 11. In the present embodiment, as shown in FIG. 4 as an enlarged view of the main part of FIG. 3, a biasing force toward the movable mold 12 is applied to the fixed mold 13 by the pre-release spring 52. . Thereby, the fixed-side mold plate 13 is separated from the fixed-side mounting plate 15 by a predetermined amount s without being separated from the movable-side mold 12 by the parting line PL.

  That is, the fixed-side template 13 moves by a predetermined amount s in the mold opening direction (the direction of arrow A in FIG. 3) with respect to the hot runner 20. Thereby, the hot runner 20 enters into the through hole 14 of the fixed side template 13 (see FIG. 4). At this time, the front end surface 20 a of the hot runner 20 is pulled away from the parting line PL (see FIG. 5) of the molded product 54.

  For this reason, the resin existing along the runner 46 from the injection port 21 is cut by a shearing action. Thus, resin stringing from the injection port 21 at the tip of the hot runner 20 is suppressed.

  Further, the fixed side insert 18 and the molded product 54 in the cavity 50 are released by the relative movement of the fixed side template 13 and the hot runner 20 at this time. Thus, the molded product 54 remains on the movable mold 12 side.

  In the present embodiment, it has been described that the fixed-side mold plate 13 moves in the mold opening direction (the direction of arrow A in FIG. 3) with respect to the fixed-side mounting plate 15 by the biasing force of the leading spring 52. Not limited to this. For example, the fixed-side mounting plate 15 may move relative to the fixed-side template 13.

  In the present embodiment, the case in which the pre-spring 52 is used to suppress the stringing of the resin at the time of release is described, but the present invention is not limited to this. For example, when the hot runner 20 is a valve gate type in which the valve pin is moved in the injection nozzle to prevent resin stringing, the leading spring 52 is not necessary.

FIG. 5 is a cross-sectional view of the injection mold 10 when the mold is opened.
When the fixed side mold plate 13 is opened by a predetermined amount S from the fixed side mounting plate 15 at the beginning of mold opening, the fixed side mold plate 13 does not move any further. Then, the fixed side mold plate 13 and the movable side mold plate 26 are released with the parting line PL as a boundary.

  The operation at this time is performed while the fixed-side template 13 is opened from the fixed-side mounting plate 15 by a predetermined amount S. Thus, the runner portion resin 55 and the center portion resin 56 are exposed to the molded product 54 on the movable mold 12 side.

FIG. 6 is a cross-sectional view of the molded product protruding after the mold opening is completed.
In this state, the protruding plate 40 moves in the arrow B direction so as to protrude toward the parting line PL. Thus, the center pin 36 and the protruding pin 39 are protruded, and the molded product 54 is taken out.

The molded product 54 is connected to the runner resin 55 and the center resin 56. Therefore, the desired molded product 54 can be obtained by finally separating them.
According to the present embodiment, since the injection port 21 of the hot runner 20 faces the direction of the runner 46, pressure loss during the resin filling process can be reduced. That is, the resin injected from the injection port 21 moves smoothly toward the runner 46. Therefore, the resin can be filled into the plurality of cavities with a uniform pressure by an inexpensive mold configuration. Moreover, since the hot runner 20 enters (retracts) into the through-hole 14 at the time of mold release, the hot runner 20 is separated from the resin in the hot runner 20 by a shearing force, so that occurrence of resin stringing can be prevented.

According to the present embodiment, a stable molding operation can be performed under such molding conditions. Furthermore, the influence of peeling of the resin injected from the injection port 21 can be eliminated for molded products that are easily affected by mold release such as optical elements.
[Embodiment 2]
7A to 7C are cross-sectional views of main parts of the injection mold 10 according to the second embodiment.

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 characterized in that the tip of the hot runner 20 in which the injection port 21 is formed is formed on a tapered surface that is inclined at a predetermined angle with respect to the mold opening / closing direction.

In the present embodiment, for convenience of description, the inclination angle with respect to the mold opening / closing direction will be described with reference to the end face 13a (parting line PL) of the fixed-side mold plate 13.
FIG. 7A shows a case where the angle α formed by the end surface 13a (parting line PL) of the fixed-side template 13 and the outlet surface 21a of the injection port 21 at the tip of the hot runner 20 is 90 °, and FIG. The case where α is 120 ° is shown, and FIG. 7C shows the case where the angle α is 135 °.

  As shown in FIGS. 7A to 7C, when the angle α is 90 ° or more and 135 ° or less, the hot runner 20 enters (retracts) into the through-hole 14 at the time of mold release, so A shearing force acts on the formed resin. Thereby, it turned out that resin is cut | disconnected and stringing of resin is suppressed.

  It is known that when the hot runner 20 is drawn into the through hole 14, the angle α is set to be larger when it is drawn. However, if the angle α is too large, the resin is difficult to cut.

Therefore, the inclination angle α is
90 ° ≦ α ≦ 135 °
Is preferable.

However, since the stringing prevention effect of the resin varies depending on the type of the resin, there may be a case where the angle α needs to be smaller than 135 °.
According to the present embodiment, the tip of the hot runner 20 in which the injection port 21 is formed is formed into a tapered surface that is inclined at a predetermined angle with respect to the mold opening / closing direction. By setting the angle α formed by the end surface 13a and the exit surface 21a of the injection port 21 at the tip of the hot runner 20 to be not less than 90 ° and not more than 135 °, stringing of the resin at the time of mold opening can be suppressed.

  For this reason, stable continuous molding can be performed without adjusting resin stringing according to molding conditions.

DESCRIPTION OF SYMBOLS 10 Injection mold 11 Fixed side mold 12 Movable side mold 13 Fixed side mold plate 13a End face 14 Through hole 15 Fixed side mounting plate 16 Through hole 17 Bolt 18 Fixed side insert 19 Locating ring 20 Hot runner 20a Inlet 21 Injection Nozzle 21a Exit surface 22 Cylinder block 23 Heater 24 Bolt 26 Movable side mold plate 27 Receiving plate 28 Movable side mounting plate 29 Bolt 31 Spacer block 32 Center hole 34 Through hole 35 Protrusion hole 36 Center pin 38 Movable side insert 39 Extrusion pin 40 Protrusion Plate 42 Guide bush 46 Runner 47 Gate 50 Cavity 52 Pre-spring 52 Molded product 55 Runner resin 56 Center resin

Claims (5)

A first mold;
A second mold disposed opposite the first mold;
A hot runner that injects resin from the tip and supplies the resin to a plurality of cavities formed between the first mold and the second mold through a plurality of runners;
A through hole formed in the first mold to slidably fit the hot runner in the mold opening and closing direction;
A molding die for injection molding, comprising: a resin outlet formed on a side surface of a tip of the hot runner so as to face the plurality of runners so as to intersect the through hole. In the molding die for injection molding according to claim 1,
It has a tipping member that is mounted between the hot runner and the first mold, and applies a biasing force to the hot runner so that the first mold can be moved relative to the mold opening and closing direction. Mold for injection molding. In the injection mold according to claim 1 or 2,
An injection mold, wherein a tip of the hot runner on which the resin outlet is formed is formed on a tapered surface inclined at a predetermined angle with respect to the mold opening and closing direction. A resin outlet formed on the side surface of the tip of the hot runner is protruded from a through hole into which the hot runner is inserted in the mold opening / closing direction, and the resin is injected in the runner direction from the resin outlet, Supplying resin through a runner to a cavity formed between a mold and a second mold disposed opposite the first mold;
A cutting step of drawing the resin outlet of the hot runner into the through hole and cutting the resin injected from the resin outlet;
And a step of separating the first mold and the second mold in a mold opening direction with a parting line as a boundary after the cutting step. In the manufacturing method of the molded article according to claim 4,
In the cutting step, the hot runner and the parting line are previously separated in the mold opening direction by a biasing force of a pre-punching member disposed in the first mold.