JP3371795B2 - Mold structure - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold structure for injection molding. 2. Description of the Related Art Conventionally, a mold shown in FIG. 10 has been used as a means for producing a waterproof rubber plug by injection molding. This consists of a base 1 having primary sprues 2, a middle plate 3 having a number of cavities 4 for molding rubber plugs, a pot plate 5 having a number of secondary sprues 6 corresponding to the cavities 4, and And a lower die 7 having a core pin 8 corresponding to. In the mold clamping state in which the base 1, the pot plate 5, the middle plate 3, and the lower mold 7 are vertically stacked,
A runner gap (not shown) for communicating the primary sprue 2 and the secondary sprue 6 is provided between the runner plate 1A of the base 1 and the pot plate 5. In this state, a fluid molding material is injected from the injection nozzle (not shown) into the respective cavities 4 in order through the primary sprue 2, the gap for the runner, and the secondary sprue 6. When the molding material is cured, the cavity 4 and the core pin 8 form a cylindrical molded product a.
At this time, these molded products a are in a state of being integrally connected to the secondary sprue portion b, the runner portion c, and the primary sprue portion d. [0003] Thereafter, when the pot plate 5, the middle plate 3 and the lower mold 7 are lowered integrally, the primary sprue 2 to the primary sprue d
Then, when the middle plate 3 and the lower mold 7 are lowered with respect to the pot plate 5, the secondary sprue portion b is torn off from the molded product a in the cavity 4 and separated. Thereafter, a molded product (rubber stopper) a is extruded from each cavity 4. In this way, a large number of molded articles a at a time from one injection nozzle
Is formed. [0004] In the above conventional mold,
In each molding step, a by-product F in which the primary sprue part d, the runner part c, and the secondary sprue part b are integrally formed as shown in FIG. 11 is generated, but this is discarded because it cannot be reused. You. Therefore, there is a problem that a large amount of material is wasted. The present invention has been made in view of the above circumstances, and has as its object to reduce waste of molding material. [0005] According to the present invention, a base having a primary sprue connected to an injection nozzle, a pool space connected to the primary sprue, and a large number of communication sprues connected to the pool space is provided. A temperature maintaining means for keeping the molding material in the primary sprue, the pool space and the communication sprue in a flowable state, and a number of secondary sprues connected to the communication sprue; A pot body , a mold body having a plurality of molding cavities connected to the secondary sprue, and a mold body that can be brought into contact with and separated from the pot plate; Dressed and fluid
Allowing the molding material in the state to pass and curing
Paper sheet material that can hold the secondary sprue section
In the case of injection molding, the molding material
Breaks through the sheet material and passes through the hole,
Of the secondary sprue portion where the broken pieces of the sheet material
The sheet material and the large number of secondary spurs
The pot portion and the mold body are integrated with each other.
By separating, the secondary steam hardened in the pot plate
The pull part is separated from the cured product in the mold body.
It was configured to be. <Operation and Effect of the Invention><Invention of Claim 1> The molding material supplied from the injection nozzle into the primary sprue, the pool space and the communication sprue is maintained in a flowable state by the temperature maintaining means. ing. When the base, the pot plate, and the mold body are clamped, and the molding material kept in a fluid state in the base is injected into the cavity through the secondary sprue, the molding material hardens in the secondary sprue and the cavity. After the curing, when the pot plate is separated from the substrate, the cured secondary sprue portion is separated from the flowing molding material in the substrate. When the pot plate and the mold body are separated from each other, the secondary sprue portion and the molded product in the cavity are separated. Thereafter, the molded product may be detached from each cavity, and the secondary sprue portion may be detached from the secondary sprue. Since only the secondary sprue is hardened and discarded except for molded products,
As compared with the conventional case where not only the secondary sprue portion but also a runner portion connecting a large number of secondary sprue portions and a primary sprue portion connected to the runner portion are discarded, waste of molding material is reduced. [0008] The fluid molding material passes through the sheet material and is supplied into the secondary sprue and the cavity. After the secondary sprue and the molding material in the cavity are hardened, when the pot plate is separated from the base, the sheet material is peeled off from the pot plate, and the secondary sprue portion is detached from the secondary sprue. Since a large number of secondary sprue portions can be separated at a time by one sheet material, work efficiency is high. Sa
Further, when the molding material passes through the sheet material, the molding material breaks the sheet material to make holes. At the periphery of the hole, the broken pieces bite into the molding material, so that the sheet material and the molding material are firmly united. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described below with reference to FIGS. The base 10 fixed above has a plate shape with a horizontal thickness.
Upper plate 11 and base body 1 fixed to the lower surface of upper plate 11
2 and a heat insulating plate 13 fixed to the lower surface of the base body 12. At the center position between the upper plate 11 and the base body 12, the upper plate 1
A primary sprue 14 penetrating from the upper surface of the base 1 to the lower surface of the base body 12 is formed. The primary sprue 14 is connected to an injection nozzle (not shown) arranged above the upper plate 11,
From here, a molding material M made of a thermosetting silicone rubber in a fluidized state flows. The lower surface of the base body 12 is shallowly recessed over most of the area, and a pool space 15 is formed between the recessed portion and the heat insulating plate 13. Further, a large number of communication sprues 16 penetrating from the pool space 15 to the lower surface of the heat insulating plate 13 are formed in the heat insulating plate 13. Further, a cooling water flow passage (temperature maintaining means, which is a constituent element of the present invention) 17 for flowing cooling water at a predetermined temperature is formed in the base body 12, whereby the pool space 15 is formed. Is kept in a fluid state without being cured. This temperature varies depending on the properties of the molding material M, and is maintained at a temperature of 60 to 80 ° C. in the case of silicone rubber as in the present embodiment. The temperature of the cooling water is set in relation to the state of heating by a heater provided in the mold body 23, which will be described later.
The temperature is set such that the molding material M is kept in a fluid state in the inside of the communication sprue 5 and in the upper part of the communication sprue 16 and in a hardened state in the lower part of the communication sprue 16. On the lower surface of the four corners of the base 10, a rod 18 having a stopper 19 whose diameter is enlarged at the lower end hangs down.
A guide hole 21 of a pot plate 20 is slidably fitted to the rod 18. Thereby, the pot plate 20 can be moved up and down between the base 10 and the stopper 19. A large number of secondary sprues 22 are formed on the upper and lower surfaces of the pot plate 20. The large number of secondary sprues 22 are arranged so as to be individually aligned with the large number of communication sprues 16, and have a longitudinal cross-sectional shape that is tapered such that the diameter decreases downward. Below the pot plate 20, a mold body 23 is provided. The mold body 23 includes a movable base 24, a lower mold 25 mounted and fixed on the movable base 24, and a lower mold 2.
And a forming plate 26 that is placed on the upper surface of the base member 5 so as to be able to be separated upward. The mold body 23 is driven up and down by a drive mechanism (not shown) between a raised position where the pot plate 20 is sandwiched between the base plate 10 and a lowered position below the rod 18. In the lowered position, the drive mechanism (not shown) horizontally drives between a position directly below the base 10 and a side position of the base 10. In the four corners of the forming plate 26 and the lower mold 25, escape holes 27 for avoiding interference with the rod 18 when the mold main body 23 rises.
Are formed. In the lower mold 25, a heater (not shown) for burying the molding material M in the cavity 28 and the secondary sprue 22 at a predetermined temperature is embedded. This temperature is set to be approximately 150 ° C. to 200 ° C. in the case of silicone rubber as in this embodiment, whereby the molding material M is cured. Formed plate 26 has a number of cavities 28 that are individually aligned with secondary sprue 22. In the inner periphery of the cavity 28, arc-shaped concave portions 29
Are formed. Further, on the upper surface of the lower mold 25, core pins 30 having arc-shaped concave portions 31 at two upper and lower positions on the outer periphery and projecting concentrically into each cavity 28 are formed. Therefore, the molded article M cured in the cavity 28
a is a rubber stopper having a cylindrical shape and having two lip portions on an outer periphery and an inner periphery. Also, the core pin 30 is
6 and 7, the dimensions are set such that a ring-shaped gap is left between the upper peripheral edge of the core pin 30 and the lower opening edge of the secondary sprue 22 as shown in an enlarged manner in FIGS. The ring-shaped gap serves as a gate G from the secondary sprue 22 to the inside of the cavity 28. A driving mechanism (not shown) for raising only the forming plate 26 from the lower die 25 when the mold body 23 is moved to the side of the base 10 is provided on the side of the base 10. Is provided. Further, above the driving mechanism, a punching jig 3 is provided so as to wait for the rising forming plate 26.
2 are arranged. The ejection jig 32 is formed by projecting a number of ejector pins 34 aligned with the cavities 28 on the lower surface of a flat support 33. When the forming plate 26 rises and approaches the ejection jig 32, Each ejector pin 34 relatively pushes out the molded article Ma in the cavity 28 downward. When the punching jig 32 pushes out the molded product Ma, the collecting device 35 moves below the molded product Ma. Further, at the time of mold clamping, a paper 36 (a sheet material which is a component of the present invention) is interposed between the lower surface of the base 10 and the upper surface of the pot plate 20. The paper 36 is easily ruptured so that the molding material M can penetrate through a small hole when the molding material M is injected in a flowing state, and has a strength capable of holding the cured molding material M at the penetrated portion. But it does not need to be a special material,
Normally used copy paper or newsprint may be used. Next, the operation of the present embodiment will be described. First, the mold body 23 is lifted, and the pot plate 20 is lifted and brought into contact with the base 10.
A paper 36 is interposed between the first sprue 14 and the heat insulating plate 13 of the base 10 (see FIG. 1).
To the injection nozzle. Next, the molding material M in a fluid state is injected into the cavity 28 through the primary sprue 14, the pool space 15, the communication sprue 16, and the secondary sprue 22 in order. At this time, the molding material M breaks the paper 36 and penetrates it while making a small hole, thereby forming the communication sprue 16.
Flows into the secondary sprue 22 (see FIG. 6). In a state where the molding material M is injected, the molding material M in the primary sprue 14 and the pool space 15 is maintained at a relatively low temperature of 50 to 60 ° C. by the cooling water, and thus maintains a fluid state. On the other hand, the molding material M in the secondary sprue 22 and the cavity 28 is cured by a heater to a relatively high temperature of 150 ° C to 200 ° C. In the communication sprue 16, the upper half portion (the portion above the broken line in FIG. 6) connected to the pool space 15 has a low temperature, and thus keeps a fluid state, and the lower half portion connected to the secondary sprue 22 has a lower temperature. It cures at high temperatures. At the position of the paper 36 where the secondary sprue 22 and the communication sprue 16 are aligned, that is, at the portion where the molding material M penetrates, the broken piece 36A of the paper 36 is hardened as shown in FIGS. Since the molding material Mb bites into the inside of the molding material M, the molding material Mb cured in the lower half portion of the communication sprue 16 is integrated with the paper 36 as a raised portion on the upper surface of the paper 36, and is also formed in the secondary sprue 22. The cured secondary sprue portion Mc is also integrated with the paper 36. When the molding material M is hardened in the secondary sprue 22 and the cavity 28 in this way, the mold body 23 descends, and accordingly the pot plate 20 also moves due to its own weight and the rubber strength at the gate G. While being placed on the mold main body 23 (see FIG. 2). Then, the molding material M in the fluid state remains in the upper half of the communication sprue 16, and the cured or semi-cured molding material Mb of the lower half of the communication sprue 16 becomes the molding material Mc cured in the secondary sprue 22. And descends together with the paper 36 (see FIG. 7). In other words, the molding material Mb that has risen slightly remains on the upper surface of the paper 36. Although the molding material M in the communication sprue 16 is in a fluid state but has a high viscosity, it does not drop from the communication sprue 16. Thereafter, the mold body 23 further descends. In this process, the pot plate 20 is engaged with the stopper 19 at the lower end of the rod 18, so that the pot plate 20 is restricted from descending. Therefore, thereafter, only the mold body 23 is lowered, and the molding plate 26 is separated from the lower surface of the pot plate 20. Here, since the secondary sprue 22 has a tapered shape with a downward taper and the lip portion of the molded product Ma is fitted in the concave portion 29 and the concave portion 31 of the core pin 30 in the cavity 28, the secondary sprue 22 is formed with the pot plate 20. With the separation of the plate 26, the secondary sprue portion Mc and the molded article Ma are respectively connected to the secondary sprue 2
2 and the cavity 28 to separate them so that they can be torn apart (see FIG. 8). Next, the mold body 23 is horizontally moved from a position directly below the base 10 to the side, and the forming plate 26 is lifted to approach the extraction jig 32. Thereafter, the lower mold 25 and the movable base 2 are moved.
Only 4 returns to the position directly below the base 10 (see FIG. 4). When the molding plate 26 is lifted, the core pin 30 is pulled out while elastically deforming the inner periphery of the molding Ma, and only the cylindrical molding Ma remains in the cavity 28. Then, in a state where the collecting device 35 has moved below the forming plate 26, the forming plate 26 is further lifted, so that the ejector pins 3
4 extrudes the molded article Ma in the cavity 28 downward,
The extruded molded article Ma falls and is collected by the collection device 35 (see FIG. 5). On the other hand, below the base 10, the pot plate 20
The paper 36 placed on the upper surface of the paper is lifted. At this time, since the secondary sprue portion Mc on the lower surface side of the paper 36 is integrated with the paper 36, it is extracted from the inside of the secondary sprue 22 (see FIG. 9). As described above, a large number of molded articles M
a (rubber stopper) is manufactured, and the cured secondary sprue portion Mc and the paper 36 are discarded. As described above, in the present embodiment, of the molding material M, what is discarded because it has hardened other than the molded article Ma is contained in the lower half portion of the secondary sprue portion Mc and the communication sprue 16. Only the portion Mb. Therefore, as compared with the conventional case where not only the secondary sprue part but also the runner part for connecting a large number of secondary sprue parts and the primary sprue part connected to this runner part are discarded, the molding material M Waste has been greatly reduced. Also, a number of secondary sprue portions Mc are
As a result, the secondary sprue 22 can be simultaneously removed from the secondary sprue 22, so that the working efficiency is excellent. <Other Embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings. For example, the following embodiments are also included in the technical scope of the present invention. In addition, various changes can be made without departing from the scope of the invention. (1) In the above embodiment, the secondary sprue portion is detached by using the sheet material. However, according to the present invention, the blowing action of the pressurized air, the suction action, and the secondary The secondary sprue portion may be detached by another method such as inserting a pin into the sprue. (2) Although the case where the molding material is a thermosetting silicone rubber has been described, the present invention is directed to a thermoplastic material when the molding material is a thermosetting material other than silicone rubber. The case can also be applied. (3) In the above embodiment, the case where the rubber stopper is formed is described, but the present invention can be applied to a molded product other than the rubber stopper. (4) In the above embodiment, paper was used as the sheet material.
According to the present invention, the material of the sheet material is not limited to paper, and the injected molding material in a flowing state can penetrate, and if the molding material cured at the penetrating portion can be held,
Any material may be used. As an example, not only a material such as paper that allows the molding material to penetrate by tearing, but also a material having fine gaps in advance, such as a woven fabric such as gauze, a resin net for a net, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a mold clamping state in Embodiment 1. FIG. 2 is a cross-sectional view of a state where a pot plate and a mold body are separated from a base. FIG. 4 is a sectional view showing a state in which a mold plate is moved to a detaching position in the mold body. FIG. 5 is a sectional view showing a state in which a molded article in a mold plate is detached from a cavity. Sectional view with the secondary sprue part removed from the pot plate. [FIG. 6] Partial enlarged sectional view with the molding material injected into the cavity. [FIG. 7] Partial enlarged sectional view with the pot plate separated from the base. FIG. 8 is a partially enlarged cross-sectional view showing a state in which the secondary sprue part and the molded product are separated from each other. FIG. 9 is a partially enlarged cross-sectional view showing a state in which the secondary sprue part is separated from the pot plate. FIG. FIG. 11 is a perspective view of a conventional by-product. 0 ... base 14 ... primary sprue 15 ... pool space 16 ... communication sprue 17 ... cooling water flow passage (temperature maintaining means) 20 ... pot plate 22 ... secondary sprue 23 ... mold body 36 ... paper (sheet material) 28 ... cavity Ma …Molding

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/84 B29C 33/00-33/76

Claims (1)

(57) [Claims] 1. A primary sprue connected to an injection nozzle.
Pool space connected to the primary sprue and
A base having a large number of communication sprues; Molding material in the primary sprue, pool space and communicating sprue
Temperature maintaining means for keeping the material flowable; Having a number of secondary sprues connected to the communication sprue,
A pot plate that can be attached to and detached from the base, It has a plurality of molding cavities connected to the secondary sprue.
And a mold body that can be moved toward and away from the pot plate.
When, Interposed between the base and the pot plate,
Allow the molding material to pass through and
Paper sheet material that can hold the next sprue.
And In the case of injection molding, the molding material replaces the paper sheet material.
It breaks and passes through the hole, and at the same time,
The broken pieces of wood material dig into the hardened secondary sprue.
The sheet material and the large number of secondary sprue portions
Integrated, By separating the pot plate and the mold body, the
The secondary sprue portion cured in the pot plate is
It is configured to be separated from the molded product cured inside That
Characteristic mold structure.