JP2772334B2 - Cassette type injection mold equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cassette type injection molding die apparatus, and more particularly to a die apparatus capable of molding a molded product having a threaded portion.

[0002]

2. Description of the Related Art In the case of molding a product having a thread portion in an injection mold, the product is molded by using a core pin having a thread cut on the outer periphery. At this time, since the core pin and the molded product are in a screwed state, when the molded product is taken out, the molded product cannot be separated from the core pin merely by protruding with the protruding pin. Therefore, the core pin is configured to be rotatable, and when the molded product is taken out, the core pin is rotated to release the screwing between the molded product and the core pin, and then the protruding pin is used to protrude.

[0003] As an injection molding apparatus having such a configuration, there is an injection molding apparatus which conventionally uses a rack and a pinion (first example).
Conventional examples: Japanese Utility Model Publication No. 30-279, JP-A-48-6
No. 6657). In this method, a rack is fixedly provided on one of the movable mold and the fixed mold, and a pinion that meshes with the rack is rotatably provided on the other, and the pinion and the core pin are connected by a wheel train mechanism. Thus, the pinion rotates on the rack as the movable mold and the fixed mold separate when the mold is opened, and the rotation is transmitted to the core pin to rotate the core pin. According to this configuration, the core pin is retracted in synchronization with the opening of the mold, and the screw engagement with the molded product is released.

Further, there is a molding machine of a cassette type in which a cavity portion is separately provided from a mold main body so that multi-product production can be performed efficiently, and the cavity portion can be detachably replaced. Japanese Patent Publication No. 3-77050 (second conventional example) discloses that a core member is provided with a rotating core pin in a nest (cassette mold). , A drive source and a rotation transmission mechanism are provided in the nest holder (mold body),
A configuration is disclosed in which the rotary transmission mechanism is connected to the rotary core when the insert is mounted on the insert holder.

[0005] Japanese Patent Publication No. 42-25773 (third conventional example) discloses that an outer periphery of a rotating shaft connected to a male screw mold having an external thread is rotatable with the rotating shaft and along the rotating shaft. A configuration is disclosed in which a control screw member slidably provided is provided, and a female screw screwed with the control screw member is fixed to the machine frame. An extruding plate is fixed to the control screw member via an auxiliary plate, and the motor, the rotating shaft and the male screw mold are fixed to the movable plate. Accordingly, when the rotational force from the motor is transmitted to the rotating shaft and the male screw mold, the screwing between the male screw member and the molded product is released, and the control screw member and the female screw are screwed together. However, since the female screw is immovably fixed to the movable platen, the control screw member advances along the rotation axis. At this time, the extrusion plate advances together with the control screw member, and pushes out the molded product from the male screw mold. Since the leads of the male screw mold and the control screw part are substantially the same, the molded product is extruded by the extrusion plate in synchronization with the release of the screwing with the male screw mold, and falls out of the mold.

[0006]

In the first and second prior arts described above, although the rotational force is transmitted by the meshing of the gears between the rotary drive mechanism and the rotary core pin, the rotary core pin does not move forward and backward by itself. That is, the screw core portion provided on the rotating core pin is in a state of being screwed with the molded product, and the molded product is immovable. Therefore, when a rotational force is applied to the rotating core pin, the screw core portion and the screw of the molded product are screwed. Forward or backward while rotating along. Therefore, when removing the rotary core pin from the molded product, the wheel train is configured to apply a rotational force in a direction in which the rotary core pin is retracted.

[0007] In such a configuration, the advance and retreat of the rotary core pin depends on the screwing of the screw core portion and the screw portion of the molded product, so that a load is applied to both screw portions. For example, just before the screw core part separates from the molded product, only a very small part of the screw core part and the screw part of the molded product are screwed together. May be damaged. Depending on the material of the molded article made of a synthetic resin, the thread portion (particularly, near the end) of the molded article is easily damaged. Immediately before the threaded core part is separated from the threaded part, a sufficient retraction driving force cannot be obtained due to a small amount of engagement between the two parts, and the retraction is stopped before the rotary core pin is completely removed from the molded product. In some cases. If a molded product removal operation is performed in that state, the screw portion of the molded product will be damaged.

In the third embodiment, since the rotary core pin (male screw mold and rotary shaft) is fixed to the movable plate and cannot move forward and backward, the molded product is formed as in the first and second embodiments. Although there is no risk of damaging the screw, the configuration becomes very complicated because an auxiliary plate and an extrusion plate are required in addition to the control screw portion and the female screw. Further, when manufacturing a molded product having a thread portion having a different shape, it is necessary to use not only a male screw mold but also a control screw portion and a female screw according to the lead of the molded product. In order to replace the part and the female screw, the entire movable side mold including the extrusion plate and the auxiliary plate must be disassembled, which is troublesome.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the risk of damaging the thread of the molded product when removing the rotary core pin from the molded product, and to disassemble the entire mold when producing molded products of different shapes. SUMMARY OF THE INVENTION It is an object of the present invention to provide a cassette type injection molding die apparatus which can easily cope with the problem.

[0010]

SUMMARY OF THE INVENTION A cassette type injection molding apparatus according to the present invention comprises a cassette mold detachably mountable on a mold body, and a cassette mold integrally removable from a mold body. A core pin that is capable of moving forward and backward with respect to the cassette mold and is rotatable with respect to the cassette mold; a screw core portion provided on the core pin and projecting into the cavity to form a desired screw portion on a molded product; and a screw core portion provided on the core pin. And a fixing screw portion provided on the cassette die and screwed to the guide screw portion.

The guide screw portion has a length equal to or longer than the screw core portion.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a cassette type injection mold apparatus according to the present invention. First, the overall outline will be described. The mold body A includes a fixed mold B including four plates 1, 2, 3, and 4 fixed to a fixed platen (not shown), and a movable platen ( (Not shown)) and a movable mold C composed of seven plates 5, 6, 7, 8, 9, 10, and 11. The locate ring 12 and the sprue bush 13 are fixed to the plate 4 of the fixed mold B.
A sprue (not shown) is inserted therein. A runner plate 14 is provided in front of the sprue bush 13. A concave portion 15 is formed in each of the plates 1 and 2, and a fixed-side cassette-type mold 16 is inserted into the concave portion 15 and fixed by a fixed key (not shown) or the like. A runner 17 formed from the sprue bush 13 to the plate 3, the runner plate 14, and the fixed-side cassette mold 16 communicates with each other. Fixed side cassette mold 1
6 are provided with positioning holes 16a.
A taper pin 19 erected on the runner plate 14 via a spring member 18 is fitted in the positioning hole 16 a, and the fixed-side cassette mold 16 is positioned in the recess 15.

In the fixed mold B, bushes 20a, 20
A guide shaft 21 stands upright through the b, and the guide shaft 21 is inserted into the escape hole 22 with the bush 20c of the movable mold C as a guide. The fixed mold B has a rack 23, meshes with a pinion 24 provided in the movable mold C, and rotation is transmitted from the pinion 24 to a wheel train group described later.

The movable mold C has a concave portion 25 provided on the plates 5, 6, and 7, and a concave portion 26 provided on the plates 8, 9. First protruding plates 27a and 27b are provided in the recess 25, and a first protruding pin 28 is fixed between the first protruding plates 27a and 27b and protrudes forward.

A movable cassette mold 29 shown in FIG. 2 is inserted into the recess 25. Movable cassette mold 29
Is a cavity plate 3 having a cavity 30 formed therein.
1, a support plate 32, side plates 33a and 33b, and a bottom plate 34
a and 34b. And these support plates 3
2. Second protruding plates 35a, 35b disposed in a space surrounded by the side plates 33a, 33b and the bottom plates 34a, 34b.
A second protruding pin 36 fixed to the protruding plates 35a and 35b and penetrating the support plate 32 and the cavity plate 31 and protruding into the cavity 30, and a fixing screw portion 37 provided on the bottom plates 34a and 34b. And a core pin 38. Like the fixed cassette mold 16, the movable cassette mold 29 is also provided with a positioning hole 29 a, and the taper pin 19 erected on the plate 6 via the spring member 18 fits into the positioning hole 29 a. In combination, the movable-side cassette mold 29 is positioned in the recess 25.

The fixing screw portion 37 and the core pin 38 will be described in detail. The fixing screw portion 37 is fixedly disposed so as to fit into a hole formed in the center of the bottom plates 34a and 34b. A female screw is engraved on the inner peripheral surface. And
The core pin 38 is formed with a screw core 39 at the tip, a guide screw 40 in the middle, and a gear 41 at the rear end. As shown in FIG. 1, the gear 41 can move forward and backward within the holes of the first protruding plates 27a and 27b. The rear end of the core pin 38 is located in the recess 26 and is supported by a bush 70 provided on the plate 10. In this embodiment, a molded product D having a female screw portion on the inner peripheral surface is formed, and a male screw having a pitch, a lead, and a length corresponding to the female screw of the molded product D is engraved on the screw core portion 39. is there. The guide screw 40 is formed with a male screw having the same lead as the screw core 39. However, this guide screw portion 40
The length in the longitudinal direction is longer than the thread portion of the screw core portion 39 and the molded product D. The fixing screw portion 37 is provided with a female screw having the same pitch and lead so that the guide screw portion 40 can be screwed.

The movable side mold C has a wheel train mechanism E including a pinion 24 as a mechanism for rotating and driving the core pin 38.
Is provided. This gear train mechanism E meshes with a drive gear 42 meshing with the gear 41 in the recess 26, a first bevel gear 43 provided coaxially with the drive gear 42, and a first bevel gear 43. A second bevel gear 44, a gear 45 provided coaxially with the second bevel gear 44,
5 and the pinion 24 provided coaxially with the gear 48. The pinion 24 meshes with the rack 23 described above. These bevel gears 43, 44 and gear 45,
46, 47, 48 are rotatably supported by mounting plates 71, 72 via bearings 49 and support members 50.

The operation of the cassette type injection molding apparatus having the above-described structure will be described below. First, the movable-side platen (not shown) is operated to bring the movable-side mold C into contact with the fixed-side mold B. At this time, the guide screw portion 40 of the core pin 38 is screwed with the female screw of the fixing screw portion 37, and the screw core portion 39 at the tip is at a position in contact with the end face of the fixed side cassette mold, and the first protrusion plate 27 a , 27b and the second protruding plates 34a, 34b are set such that the tip of the second protruding pin 36 is located on the bottom surface of the cavity 30 (see FIGS. 1, 3).

Then, a resin material is filled into the cavity 30 through a runner 17 from a sprue (not shown). At this time, as shown in FIG. 3, a molded product D having a female screw having a shape (lead, pitch, etc.) corresponding to the screw core portion 39 is formed in the cavity 30.

When the resin in the cavity 30 has hardened after a predetermined time has elapsed, a mold opening operation is performed. First, the platen (not shown) is driven to move the movable mold C to the left in the drawing. At this time, the pinion 24 screwed with the rack 23 fixed to the fixed mold B moves to the left in the drawing while rotating. Then, simultaneously with the rotation of the pinion 24, the coaxial gear 48 rotates, and accordingly, the gear 4
7, 46, 45, bevel gears 44, 43 rotate, and further, gear 41 rotates via a drive gear 42 provided coaxially with bevel gear 43. Thereby, the core pin 38 rotates. The core pin 38 retreats while rotating because the guide screw portion 40 and the fixing screw portion 37, and the screw core portion 39 and the female screw portion of the molded product D are screwed with each other (see FIG. 4). In addition, by configuring the wheel train mechanism E in consideration of the screw directions of the screw core portion 39 and the guide screw portion 40,
The core pin 38 is configured to retract when the mold is opened. Further, at least when the mold opening is completed, the screw core portion 39 is configured to completely escape from the molded product D.

When the mold opening is completed in this manner, the first protruding plate 27a,
27b is pushed forward, and the first push-out pin 2
8 advances and presses the second protruding plates 35a and 35b. When the second protruding plates 35a and 35b move forward, the second protruding pins 36 fixed thereto also move forward,
The molded article D is protruded from the cavity 30 (see FIG. 5).

When molding is performed in the above steps, first and second moldings are performed.
After the protruding pins 28 and 36 are retracted, the platen (not shown) is driven again, the movable mold C is moved rightward in the drawing, and the mold is clamped. At this time, the core pin 38 moves forward while rotating by the wheel train mechanism E including the rack 23 and the pinion 24, and returns to the state shown in FIG.

In a conventional molding machine, when the core pin is driven forward and backward only by screwing the screw core portion and the threaded portion of the molded product without having the guide screw portion, the core pin is disengaged from the molded product when the threaded core portion escapes from the molded product. Stops retreating (the rotation of the core pin can continue). Therefore, the retraction of the core pin due to the rotation is unstable immediately before the screw core portion escapes from the molded product. For example, in the case where the screw core portion is pulled out at a stretch by applying some force when the screw core portion escapes from the molded product, the thread groove or the thread at the end portion of the molded product is damaged.
Immediately before the core pin separates from the molded product, there is only a small portion where the threaded core portion and the threaded portion of the molded product are engaged.Therefore, sufficient retraction force cannot be obtained, and the core pin comes out of the molded product. You may not be able to advance or retreat. If the process proceeds to the protruding step in this state, the screw portion of the molded product is also damaged. As described above, in the configuration in which the core pin is advanced and retracted by using only the screwing of the thread portion itself of the molded product, the thread groove or the screw thread at the end of the molded product is easily damaged, and the desired shape may not be obtained. Was. Further, there is a possibility that an excessive force is applied to the threaded portion of the molded product in order to drive the core pin forward and backward.
In particular, when the resin molded product was soft, the possibility of breakage of the screw portion was high.

On the other hand, in the configuration according to the present invention, since the guide screw portion 40 and the fixing screw portion 37 are provided, not only the molded product D and the screw core portion 39 are screwed but also the guide screw portion 40 and the fixing screw portion. Core pin 3 using 37
Since the 8 is driven forward and backward, no excessive force is applied to the molded article D. The length of the guide screw portion 40 in the longitudinal direction is:
Since the screw pin 39 is longer than the screw core 39, the core pin 38 continues to retreat by the screwing of the guide screw 40 and the fixing screw 37 even after the screw core 39 escapes from the molded product. Accordingly, even when the screw core portion 39 escapes from the molded product, the core pin 38 stably rotates and retreats. Therefore, unlike the conventional case, the thread groove and the thread at the end of the molded product D are not damaged. Rather, since the core pin 38 retreats while rotating reliably, the molded product D
Screw grooves and threads can be more accurately engraved.
Since the screw core portion 39 and the guide screw portion 40 are formed so as to have the same lead, there is no hindrance to the advance / retreat of the core pin 38.

Further, the configuration using the extruded plate with the rotary core pin fixed in a non-movable manner is extremely complicated, and the mold apparatus is disassembled every time a molded product having a screw portion of a different shape is manufactured. Then, it was necessary to replace it, and it was troublesome. On the other hand, in the configuration of the present invention, the extrusion plate and the auxiliary plate are unnecessary, and the configuration is relatively simple.

Further, since the core pin 38 is detachable from the movable mold C as a part of the movable cassette mold 29, the core pin 38 can be removed from the movable mold C. By exchanging the cassette mold 29 and the core pin 38 accordingly, the screw core 39 has a shape corresponding to the thread of the desired molded product, and the guide screw 40 and the fixing screw 37 also correspond to the shape. Therefore, it is possible to arbitrarily manufacture a molded product having a screw portion of a desired shape without changing the mold body. In addition, this exchange can be easily performed without disassembling the mold body. As described above, according to the present invention, since the guide screw portion is provided on the rotary core pin and the rotary core pin is provided on the movable cassette mold, it is possible to easily cope with a molded product having screw portions having various leads. That is, when a large number of cassette dies for replacement are manufactured, there is no limit in manufacturing a molded product having an arbitrary threaded portion. Will be possible.

Since the core pin 38 is rotated and moved back and forth by the action of the rack 23 and the pinion 24 in conjunction with the mold opening operation, the core pin 38 can be operated at a precise timing without requiring a drive source. In this embodiment, one rack 23 is provided. However, a pair of racks are provided so as to be opposed to each other with the pinion 24 interposed therebetween, and one of the racks is selectively screwed to the pinion 24. A configuration is also possible. In that case, it is possible to determine which rack to use depending on whether the threaded portion to be engraved on the molded product is a right-handed screw or a left-handed screw.

In the above embodiment, the core pins 38 are provided on the movable-side cassette mold 29, but it is also possible to adopt a configuration in which core pins are provided on the fixed-side cassette mold. Such an embodiment is shown in FIG.

FIG. 6 shows only the movable-side cassette mold 51 and the fixed-side cassette mold 52. The movable cassette mold 51 includes a cavity plate 54 having a cavity 53 formed therein, a support plate 55, and side plates 56a and 56b.
And bottom plates 57a and 57b. Then, the second protruding plates 58a, disposed in the space surrounded by the plate-like members 55, 56a, 56b, 57a, 57b,
58b and a second protruding pin 59 fixed to the protruding plates 58a and 58b. The second protruding plates 58a and 58b and the second protruding pin 59
When the mold is opened, a first ejecting pin (not shown) is pushed forward by projecting through the hole 60 to push the mold out.
The molded product F in 3 is pressed.

The fixed-side cassette mold 52 includes a main plate 6
1, a support part 62, a fixing screw part holder 63, and a core pin 64. The core pin 64 has a screw core 65 at the front end, a guide screw 66 at the middle, and a gear 67 at the rear end. The screw core 65 can form a desired screw on a molded product. The guide screw portion 66 is screwed with the female screw of the fixing screw portion 68 provided on the support portion 62, has the same lead as the screw core portion 65, and has a longer length in the longitudinal direction than the screw core portion. Has become. Although not shown, a rotation drive mechanism is provided in the fixed mold,
The wheel train meshes with the gear 67. Therefore, when the gear 67 is rotated by a rotation driving mechanism (not shown), the core pin is retracted by the screwing of the guide screw portion 66 and the fixing screw portion 68 and can be separated from the molded product F. Other configurations are basically the same as those of the first embodiment. As described above, the configuration is not limited to the configuration in which the rotating core pins are provided in the movable-side cassette mold, and it is also possible to provide the rotating core pins in the fixed-side cassette mold or to provide the rotating core pins in both cassette molds. .

[0031]

As described above, according to the present invention, a guide screw portion is provided on a core pin, a fixing screw portion is provided on a cassette mold, and the core pin is driven forward and backward by utilizing the engagement of the two.
The core pin always advances and retreats reliably and stably, and there is no risk of breakage without imposing an excessive load on the thread portion of the molded product. Further, by using a cassette die having a core pin having different screw shapes of the screw core portion and the guide screw portion, it is possible to form a molded product having a screw portion of an arbitrary shape, and it is extremely easy to replace and remove the molded product. What can be done.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a clamped state of a cassette type injection molding apparatus according to the present invention.

FIG. 2 is an enlarged sectional view showing a cassette mold.

FIG. 3 is a partially cutaway sectional view showing an enlarged main part of FIG. 1;

FIG. 4 is a sectional view showing a mold open state of the cassette type injection mold apparatus shown in FIG. 1;

FIG. 5 is a cross-sectional view showing a state in which a molded product is ejected from the cassette-type injection mold apparatus shown in FIG. 1;

FIG. 6 is an enlarged sectional view showing a pair of cassette dies of the second embodiment.

[Explanation of symbols]

 Reference Signs List A Mold body B Fixed mold C Moving mold D Molded product 16 Fixed cassette mold 29 Movable cassette mold 30 Cavity 37 Fixed screw part 38 Core pin 39 Screw core part 40 Guide screw part 51 Fixed cassette metal Mold 52 Movable cassette mold 53 Cavity 64 Core pin 65 Screw core 66 Guide screw 68 Fixing screw

Claims (2)

(57) [Claims] 1. A cassette mold that can be attached to and detached from the mold body, and can be integrally attached to and detached from the mold body and can be moved back and forth with respect to the cassette mold. A rotatable core pin, a screw core portion provided on the core pin and projecting into the cavity to form a desired screw portion on a molded product; a guide provided on the core pin and having the same lead as the screw core portion A cassette type injection molding die apparatus, comprising: a screw part; and a fixing screw part provided in the cassette die and screwing with the guide screw part. 2. The cassette type injection molding apparatus according to claim 1, wherein the guide screw portion has a length longer than the screw core portion.