JP2003159727A - Injection mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To overcome such a problem that it is hard to easily and rapidly replace worn-out and damaged parts in a conventional hot-runner type injection mold using a gate valve. <P>SOLUTION: This injection mold is equipped with: a fixed-side mold 11 in which a recess 12 is formed in a part of a parting surface FP, a supporting block 14 which is removably fixed to the recess 12 of the mold 11 via attachment/detachment means 16-18 and forms a part of the parting surface FP of the mold 11, and a nozzle tip 21 which is removably fitted into the supporting block 14 from the other side of the parting surface FP and in which a gate 22 facing the parting surface FP is opened at a tip. The nozzle tip 21 is held in a state of being sandwiched between the supporting block 14 and a nozzle holder 19 which is inserted into the supporting block 14 via the mold 11, and the gate 22 is opened/closed by using a gate pin 27 which is housed in the nozzle holder 19. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot runner type injection molding die using a gate valve, and more particularly to a resin containing magnetic powder or fibrous crystal which is highly likely to accelerate wear of a nozzle tip. It is suitable for use in injection molding.

[0002]

2. Description of the Related Art In a hot runner type injection molding die using a gate valve, there is a portion having a very small resin passage cross-sectional area, such as in the vicinity of a gate. In the case of a plastic bond magnet material containing a magnetic powder having a high hardness, the filling peak pressure at the time of injection molding increases, and the wear of the nozzle tip formed with the gate tends to progress very quickly. Therefore, when injection-molding a plastic bond magnet material with a hot runner type injection molding die that uses a gate valve, the nozzle tip with the gate formed, the gate pin for opening and closing the gate, the fixed side die and the movable side It has been pointed out that the gate portion that is formed between the mold and the mold cavity and that communicates with the mold is heavily worn, and that the appearance of defects such as burrs tends to occur in the molded product, resulting in poor mass productivity.

As prior arts, Japanese Patent Publication No. 5-33887, Japanese Patent Publication No. 7-67715 and Japanese Patent Publication No. 7-1.
In the 0548 publication, in a hot runner type resin injection molding die that uses a gate valve, the gate of the nozzle mounted at the tip of the heating cylinder is configured with a replaceable nozzle block attached to the gate valve device. , Which enables replacement when the gate portion is damaged.

[0004]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 5-33887
Publication and Japanese Patent Publication No. 7-67715 and Japanese Patent Publication No. 7-
In the case of the conventional injection molding die disclosed in 10548, in order to replace the nozzle block, the injection molding die is removed from the injection molding machine, and the gate valve device is taken out after disassembling it. The nozzle block must be replaced, and workability is extremely poor. Especially when the nozzle block is heavily worn like the plastic bond magnet material described above, it is necessary to frequently replace the nozzle block, so workability is significantly impaired with such a structure, and the operating rate of the device is reduced. It is necessary to make some improvements so as not to invite

Further, the plastic bond magnet material has poor fluidity as compared with a general synthetic resin material alone, and it is necessary to raise the resin temperature to a temperature higher than these, for example, about 250 ° C. In addition, when a plastic bond magnet material is injection molded, heat generated near the gate is transferred to the molding cavity side, and there is a problem in that appearance defects such as surface peeling due to burning of the material occur. Special fair 7 mentioned above
No. 10548 discloses that a nozzle block is provided with a temperature adjusting portion and a cooling hole to adjust the molten resin passing through the gate to a preferable state. However, in such a cooling mode, a plastic bond magnet is used. When materials are used, cooling is insufficient, and more efficient cooling is required.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to replace a wear-damaged part in a hot runner type injection molding die using a gate valve, even when handling a plastic bond magnet material which easily promotes wear of a resin passage. An object of the present invention is to provide an injection mold that can be easily and quickly performed.

[0007]

An injection molding die according to the present invention is a fixed-side die in which a recess is formed in a part of a parting surface, and is removed from the fixed-side die by a detaching means. Support block which is fixedly fixed and forms a part of the parting surface of the fixed mold, and detachably fitted to the support block from the opposite side of the parting surface of the fixed mold. And a nozzle tip having a gate facing the parting surface of the fixed-side die and having an opening at the tip, the nozzle tip being inserted into the support block through the support block and the fixed-side die. And a gate pin held between the nozzle holder and the nozzle holder and accommodated in the nozzle holder to open and close the gate.

According to the present invention, the molten resin is injected from the gate into the molding cavity formed between the fixed mold and the movable mold. When the injection work of the molten resin is completed, the gate is closed by the gate pin, and the mold opening is performed so that the movable mold is separated from the fixed mold. If the nozzle tip becomes worn, the support block is removed from the stationary mold by the attaching / detaching means in this mold open state, the nozzle tip fitted in the support block is replaced with a new one, and then the support block is removed again. It is fixed to the fixed side mold by the attaching / detaching means and the injection work is restarted.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the injection-molding die according to the present invention, the attaching / detaching means includes a bolt mounting hole opened on the parting surface of the support block and a female screw hole formed on the fixed side mold and communicating with the bolt mounting hole. And a bolt that is mounted in the bolt mounting hole and screwed into the female screw hole, or that is formed on the inner peripheral surface of the concave portion of the fixed-side mold and the outer peripheral surface of the support block and is formed on the female screw portion. It may have a male screw part to be screwed. Alternatively,
A locking projection that can project and retract in a direction parallel to the parting surface of the fixed-side die, drive means that drives the locking projection to project and retract, and a locking recess that can engage with the locking projection. Or a ball plunger having a sphere capable of projecting and retracting in a direction parallel to the parting surface of the fixed side mold and a biasing means for urging the sphere in a projecting direction, and the sphere of the ball plunger is locked. And a locking recess that can be used.

The support block may further include temperature adjusting means incorporated adjacent to the nozzle tip. In this case, the temperature adjusting means may be an electric heater, or may have a temperature adjusting medium passage for passing a heat medium or a refrigerant.

The concave portion of the fixed mold further has a fitting concave portion formed with a conical tapered surface having a central axis line perpendicular to the parting surface thereof, and the support block has a fitting concave portion. It is possible to further have a fitting convex portion formed with a tapered surface that can be tightly fitted to the tapered surface.

The resin passing through the gate may contain magnetic powder. Examples of such resins include Ba-based and Sr-based ferrite magnetic materials, Sm-Co-based and Nd-based materials.
-Fe mixture such as rare earth magnetic material such as Fe, carbonyl iron powder, other metal or alloy powder, one or more kinds of arbitrary magnetic powder such as soft magnetic ferrite, and a binder such as nylon. Mention may be made of a pelletized plastic bonded magnet compound produced by smelting.

In addition to the above, as a molding material to which the present invention is particularly desirable, a fiber reinforced plastic material such as high density polyethylene mixed with heat resistant fibers such as glass fiber, graphite fiber and sapphire whiskers, and heat There are curable resins filled with organic fibers, wood fibers, asbestos, etc., and as conductive plastic materials, POM (polyoxymethylene) resin and PP
Examples include S (polyphenylene sulfide) resin filled with carbon fibers.

[0014]

EXAMPLES Examples of the injection molding die according to the present invention will be described in detail with reference to FIGS. 1 to 4, but the present invention is not limited to these examples, and further combinations or All changes and modifications that come within the concept of the invention as defined in the claims of the specification are possible and thus of course applicable to other techniques which belong to the spirit of the invention.

Japanese Patent No. 3160874 (Japanese Patent No. 3090)
No. 157), Japanese Patent Publication No. 5-33887, Japanese Patent Publication No. 7-
Japanese Patent Publication No. 67715, Japanese Patent Publication No. 7-10548, and the like disclose the basic configurations of an injection molding die and an injection molding device in which the injection molding die is incorporated, which are objects of the present invention. Since the basic configuration of the above is well known, description of those parts that are not directly related to the present invention will be omitted, and only the main part of the present invention will be described below.

FIG. 1 shows the cross-sectional structure of the main part of the first embodiment. That is, in the central portion of the parting surface Fp of the fixed-side mold 11 that faces the movable-side mold (not shown),
A recess 12 is formed. In the center of this recess 12,
A fitting recess 13 having a conical tapered surface having a central axis line perpendicular to the parting surface Fp is further formed. A support block 14 forming a part of the parting surface Fp of the stationary mold 11 is embedded in the recess 12 and the fitting recess 13. The support block 14 is provided with a fitting projection 15 having a tapered surface that can be tightly fitted to the taper surface of the fitting recess 13, so that the support block 14 with respect to the fixed-side mold 11 is supported. The positioning can be performed accurately. That is,
The concave portion 12 and the fitting concave portion 13 of the fixed-side mold 11 have a shape substantially corresponding to the contour shape of the support block 14.

A plurality of female screw holes 16 are formed in the bottom of the recess 12 of the fixed side mold 11. A plurality of bolt mounting holes 18 for inserting bolts 17 that can be screwed into the female screw holes 16 are formed on the parting surface Fp of the support block 14.
Each has an opening. These bolt mounting holes 18
Is a stepped hole in which, for example, the head of a hexagon socket head cap bolt can be embedded, and is set so that the head of the bolt 17 does not protrude from the parting surface Fp. The female screw hole 16, the bolt mounting hole 18, and the bolt 17 function as the attaching / detaching means of the present invention. That is, the support block 14 can be integrally fixed to the fixed-side mold 11 by screwing the bolt 17 into the fixed-side mold 11 through the bolt mounting hole 18. On the contrary, by removing the bolt 17 from the female screw hole 16 of the fixed-side mold 11, the support block 14 can be removed from the fixed-side mold 11.

A holder accommodating hole 20 for accommodating the nozzle holder 19 at the tip of a heating cylinder (not shown) through the fixed mold 11 is formed in the center of the support block 14. At the center of the bottom of the holder housing hole 20, a nozzle tip 21 that is removable from the opposite side of the parting surface Fp of the stationary mold 11 is fitted. A gate 22 facing the parting surface Fp of the stationary die 11 is opened at the tip of the nozzle tip 21. The nozzle tip 21 is sandwiched between the nozzle holder 19 and the support block 14 while being fitted to the nozzle holder 19 described above. The nozzle tip 21 is pressed against the bottom portion of the holder housing hole 20 by receiving the pressure of the molten resin interposed in the nozzle holder 19, but the nozzle tip 21 is pressed by the molten resin passing through the gate 22 from the nozzle holder 19. An appropriate play, that is, a gap Gp, is formed between the nozzle tip 21 and the nozzle holder 19 to allow the thermal expansion so as to allow the thermal expansion.

The outer peripheral surface of the nozzle holder 19 in which the water jacket 23 is formed is covered with a heat insulating material 24.
Surrounded by 5, the nozzle holder 19 can be kept at an appropriate temperature.

The support block 14 includes a nozzle tip 21.
A temperature adjusting medium passage 26 is formed so as to surround the temperature adjusting medium passage 26, and a heat medium or a refrigerant for keeping the nozzle tip 21 at an appropriate temperature is passed through the temperature adjusting medium passage 26. Has become. As a heat medium or refrigerant,
Water, oil or air can be used. When it is not necessary to cool the nozzle tip 21, it is effective to incorporate an electric heater in place of the temperature adjusting medium passage 26.

Opening and closing of the gate 22 is switched by the reciprocating motion of the gate pin 27 incorporated in the nozzle holder 19, and the molten resin for the molding cavity (not shown) formed between the fixed mold 11 and the movable mold is formed. Supply and supply stop. In this case, it is desirable that the gate pin 27 be formed of a material having a hardness lower than that of the nozzle tip 21 to suppress the wear of the nozzle tip 21 as much as possible.

When the molten resin contains hard particles such as magnetic powder, wear of the gate 22 portion of the nozzle tip 21 having a small passage cross-sectional area proceeds, so that the nozzle tip 21 can be worn at an appropriate time. It is necessary to replace the gate pin 27, etc. When replacing the nozzle tip 21,
With the mold open, remove the bolt 17 to remove the fixed mold 11.
After removing the support block 14 from the nozzle and replacing the nozzle tip 21 fitted on the bottom of the holder housing hole 20 with a new nozzle tip 21, the support block 14 is again fixed to the recess 12 and the fitting recess 13 of the stationary mold 11. The nozzle holder 19 into the holder accommodating hole 20 of the support block 14, and the nozzle tip 21 is attached to the tip of the nozzle holder 19.
The bolt 17 is screwed into the female screw hole 16 of the fixed-side mold 11 in a state of being fitted and held, and the support block 14 is integrally fixed to the fixed-side mold 11.

In the above-described embodiment, the support block 14 is detachably fixed to the fixed-side mold 11 by using the bolt 17, but as the attaching / detaching means according to the present invention, such a bolt 17 or the like is used. Other than the above, the following configurations can be adopted.

FIG. 2 shows a sectional structure of a portion of the support block 14 in another embodiment of the injection mold according to the present invention. That is, a male screw portion 28 is formed on the outer peripheral surface of the support block 14, and a female screw portion 29 with which the male screw portion 28 is screwed is formed on the inner peripheral surface of the recess 12 of the stationary mold 11.
The male screw portion 28 and the female screw portion 29 constitute the attaching / detaching means. When the support block 14 is attached to or detached from the fixed mold 11, the parting surface F of the support block 14 is used.
The outer periphery of the flange portion 30 formed on the p-side is gripped by using a jig or the like not shown, and the entire support block 14 is rotated with respect to the fixed-side die 11 to thereby fix the fixed-side die 11
On the other hand, the support block 14 can be attached and detached.

In this embodiment, the bolt mounting hole 18 as in the previous embodiment is formed on the parting surface Fp of the support block 14.
Since it is not necessary to open the opening, it is possible to avoid damage to the parting surface Fp of the movable mold by only setting the flange portion 30 to a large diameter as necessary. Note that FIG.
In the above, elements having the same functions as those in the previous embodiment are designated by the same reference numerals.

FIG. 3 shows a sectional structure of a portion of the support block 14 in another embodiment of the injection mold according to the present invention. That is, on the inner peripheral surface of the concave portion 12 of the fixed-side mold 11, an annular casing 31 and a plurality of housing holes 32 formed radially with respect to the casing 31,
Steel balls 33 that can be respectively housed in the housing holes 32 and can project from and retract from the inner peripheral surface of the casing 31 in a direction parallel to the parting surface Fp, and steel balls 33 that are housed in the housing holes 32 together with the steel balls 33. A ball plunger 35 having a spring 34 for urging 33 in a direction projecting from the inner peripheral surface of the casing 31 is integrally incorporated.
4 can be moved to the outer side in the radial direction of the casing 31 by a driving means (not shown). Further, on the outer peripheral surface of the support block 14, there are formed locking recesses 36 to which the spherical bodies of the ball plunger 35 can be locked respectively. Therefore, when the support block 14 is removed from the stationary mold 11, the spring 34 for urging the steel ball 33 toward the locking recess 36 is retracted to move the steel ball 3
The spring force of the spring 34 with respect to 3 is eliminated, and the support block 14 is pulled out from the fixed-side die 11 using its own weight. On the contrary, when the support block 14 is attached to the fixed mold 11, the spring 34 is moved forward to the original biasing position, and the steel ball 3
3 is inserted into the casing 31 against the spring force of the spring 34 protruding from the inner peripheral surface of the casing 31, and the steel ball 33 is engaged with the locking recess 36 formed on the outer peripheral surface of the support block 14. Stop it.

Also in this embodiment, since it is not necessary to open the bolt mounting hole 18 in the parting surface Fp of the support block 14 as in the first embodiment, the parting of the movable die by such opening is performed. It is possible to avoid damage to the surface Fp. In FIG. 3, elements having the same functions as those in the previous embodiment are designated by the same reference numerals.

FIG. 4 shows a sectional structure of a portion of a support block 14 in still another embodiment of the injection mold according to the present invention. That is, the recess 12 of the fixed mold 11
An annular casing 31 is integrally incorporated into the inner peripheral surface of the. A plurality of accommodation holes 32 are radially formed in the casing 31. Inside the housing holes 32, the casing 3 is arranged in a direction parallel to the parting surface Fp.
Retaining claws 37 that can be projected and retracted from the inner peripheral surface of No. 1 are respectively stored. A driving means (not shown) that drives the locking claw 37 to reciprocate in the accommodation hole 32 is connected to the locking claws 37. The drive means is a hydraulic mechanism or casing 31.
It may be a scroll type in which the locking claw 37 is projected and retracted by turning the outer periphery of the. Locking recesses 36 are formed on the outer peripheral surface of the support block so that the tips of the locking claws 37 can be locked respectively. Therefore, the fixed mold 11
When the support block 14 is removed from the support block 14, the driving means is operated to return the locking claw 37 into the accommodation hole 32, thereby releasing the engagement state of the locking claw 37 with the locking recess 36 of the support block 14. The support block 14 can be removed from the fixed-side mold 11 by using its own weight or the like. On the contrary, when the support block 14 is mounted on the stationary mold 11, the support block 14 is inserted into the casing 31 with the locking claws 37 returned to the accommodation holes 32, and the drive means is operated in this state. Operate the locking claw 37 to support block 1
The support block is integrally connected to the stationary mold 11 by projecting it into the locking recess 36 of No. 4 and switching them to the engaged state.

Also in this embodiment, since it is not necessary to open the bolt mounting hole 18 in the parting surface Fp of the support block 14 as in the first embodiment, the parting of the movable die by such opening is performed. It is possible to avoid damage to the surface Fp. In FIG. 4, elements having the same functions as those of the previous embodiment are designated by the same reference numerals.

[0030]

According to the injection molding die of the present invention, a support block is formed in which a recess is formed in a part of the parting surface of the stationary mold and a part of the parting surface of the stationary mold is formed. The nozzle chip, which is detachably fixed to the concave portion of the fixed-side die through the attaching / detaching means, has a gate opening toward the tip of the parting surface of the fixed-side die, and the gate is open to the support block. From the opposite side, the nozzle tip is sandwiched between the support block and the nozzle holder that is inserted into the support block through the fixed side mold, and the gate pin accommodated in this nozzle holder opens and closes the gate. Therefore, if the nozzle tip becomes worn, the nozzle holder should be removed from the support block and the support block should be removed from the stationary mold using the attaching / detaching means. Ri, a new nozzle tip can be easily and quickly mounted by removing the worn nozzle tip from the support block. Especially when the resin passing through the gate contains a hard material such as magnetic powder,
Although it becomes necessary to frequently replace the nozzle tip due to wear, this replacement operation can be performed more easily and quickly.

The attaching / detaching means is attached to the bolt mounting hole opened on the parting surface of the support block, the female screw hole formed in the fixed mold and communicating with the bolt mounting hole, and the bolt mounting hole is attached to and screwed into the female screw hole. In the case of having a bolt, the bolt can be pulled out and tightened from the parting surface side, so that the workability of attaching / detaching the support block to / from the stationary mold can be better maintained.

When the attaching / detaching means has a female screw portion formed on the inner peripheral surface of the concave portion of the fixed mold and a male screw portion formed on the outer peripheral surface of the support block and screwed into the female screw portion, the fixed side By rotating the support block with respect to the mold,
The support block can be easily attached to and detached from the stationary die, and since part of the attaching / detaching means is not exposed on the parting surface, damage to the parting surface of the movable die can be prevented.

The attaching / detaching means engages and disengages in a direction parallel to the parting surface of the fixed side mold, the driving means for driving the engaging and disengaging projections into and out, and the engaging protrusion. In the case of having a locking concave portion that can be fitted, the supporting convex portion can be made to appear and disappear by the driving means, so that the supporting block can be easily attached / detached to / from the stationary mold, and the attaching / detaching means can be attached to the parting surface. Since a part of is not exposed, damage to the parting surface of the movable mold can be prevented.

A ball plunger having a sphere whose attaching / detaching means can move in and out in a direction parallel to the parting surface of the fixed mold, and a urging means for urging the sphere in a protruding direction, and a sphere of the ball plunger. In the case where the supporting block has a lockable recess, the supporting block can be easily attached to and detached from the fixed side mold against the biasing force of the biasing means without using a special drive source. Since part of the attaching / detaching means is not exposed on the parting surface, it is possible to prevent the parting surface of the movable mold from being damaged.

When the electric heater and the temperature adjusting means having the temperature adjusting medium passage for passing the heat medium or the refrigerant are incorporated in the support block in the vicinity of the nozzle tip, the molten resin interposed in the gate and in the vicinity thereof. It is possible to adjust the temperature inside the resin passage and the cavity formed between the fixed-side mold and the movable-side mold to the optimum temperature, and it is possible to eliminate appearance defects such as burning due to overheating.

A fitting recess having a conical taper surface having a central axis perpendicular to the parting surface of the fixed mold is further provided in the recess of the fixed mold, and the tapered surface of the fitting recess is provided. In the case where the support block is further provided with the fitting convex portion formed with the tapered surface that can be tightly fitted to the support block, the positioning of the support block with respect to the fixed mold can be performed extremely accurately and quickly.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic structure of a main part in an embodiment of an injection molding die according to the present invention.

FIG. 2 is a sectional view showing a schematic structure of a main part in another embodiment of the injection mold according to the present invention.

FIG. 3 is a sectional view showing a schematic structure of a main part in another embodiment of the injection mold according to the present invention.

FIG. 4 is a cross-sectional view showing a schematic structure of a main part in still another embodiment of the injection molding die according to the present invention.

[Explanation of symbols]

11 Fixed mold 12 recess 13 Fitting recess 14 Support block 15 Fitting convex part 16 female screw hole 17 Volts 18 bolt mounting holes 19 nozzle holder 20 Holder accommodation hole 21 nozzle tip 22 gates 23 Water jacket 24 Insulation 25 heater 26 Temperature control medium passage 27 Gate Pin 28 Male thread 29 Female thread 30 Flange 31 casing 32 accommodation hole 33 steel balls 34 spring 35 ball plunger 36 Locking recess 37 Locking claw Fp Parting surface Gp gap

Claims (10)

[Claims] 1. A fixed-side mold having a recess formed in a part of a parting surface, and a part of the fixed-side mold which is detachably fixed to the recess of the fixed-side mold by a detachable means. A supporting block forming a part of the molding surface, and detachably fitted to the supporting block from the opposite side of the parting surface of the fixed side mold, to the parting surface of the fixed side mold. The facing gate comprises a nozzle tip having an opening at the tip, and the nozzle tip is sandwiched between the support block and a nozzle holder inserted into the support block through the fixed mold, and is accommodated in the nozzle holder. An injection mold, wherein the gate is opened and closed by a gate pin. 2. The attachment / detachment means includes a bolt mounting hole that opens to the parting surface of the support block, a female screw hole that is formed in the stationary mold and communicates with the bolt mounting hole, and the bolt mounting hole. The injection mold according to claim 1, further comprising: a bolt mounted on the female screw hole and screwed into the female screw hole. 3. The attaching / detaching means includes a female screw portion formed on an inner peripheral surface of the concave portion of the fixed mold, and a male screw portion formed on an outer peripheral surface of the support block and screwed into the female screw portion. The injection mold according to claim 1, further comprising: 4. The attachment / detachment means includes a locking projection that can project and retract in a direction parallel to the parting surface of the stationary mold.
The injection molding die according to claim 1, further comprising a driving means for driving the locking convex portion into and out of the locking convex portion, and a locking concave portion with which the locking convex portion can be engaged. 5. A ball plunger having a sphere capable of projecting and retracting in a direction parallel to the parting surface of the stationary die and a urging means for urging the sphere in a protruding direction, and the ball. The injection mold according to claim 1, further comprising: a locking recess that can lock the sphere of the plunger. 6. The injection-molding die according to claim 1, wherein the support block further has a temperature adjusting means incorporated near the nozzle tip. 7. The injection mold according to claim 6, wherein the temperature adjusting means is an electric heater. 8. The injection mold according to claim 6, wherein the temperature adjusting means has a temperature adjusting medium passage for passing a heat medium or a refrigerant. 9. The fixed concave die further has a fitting concave formed with a conical taper surface having a central axis perpendicular to the parting surface, and the supporting block is The injection according to any one of claims 1 to 8, further comprising a fitting convex portion formed with a tapered surface capable of tightly fitting with the tapered surface of the fitting concave portion. Molding die. 10. The resin passing through the gate contains a magnetic powder, according to any one of claims 1 to 9.
The injection mold according to any one of 1.