JPH0570926U - Injection mold - Google Patents

Abstract

(57) [Summary] [Purpose] Even if it is a bellows injection molded product using a core mold, it is easy to take out the molded product. [Structure] The core die 3 is composed of a plurality of core pieces 5, 5, ..., 5 divided in the moving direction of the projecting rod 4, and the projecting rod 4 is provided.
, 5 are supported so that they can move in the protruding direction, and the core pieces 5, 5, ... Child piece 5,
5, ..., Steps 6, 6, which come into contact with each other at different positions
, 6 are provided so that the projecting fluid is blown out from the gaps 7, 7, ..., 7 generated between the respective core pieces 5, 5 as necessary, and the projecting rod 4 projects with the projecting movement of the projecting rod 4. Stick 4
, 6 contact the corresponding core pieces 5, ..., 5 and push them out one by one, and the core mold 3 is divided into a plurality of parts in the projecting direction, and the respective division gaps 7 ,. If necessary, a projecting fluid is blown from 7 to make the fluid flow around the entire molded article 18 instantly and uniformly so that the molded article is blown away.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an injection molding die. More specifically, the present invention relates to a molded product take-out mechanism for an injection mold for molding a molded product, for example, a bellows-shaped cylindrical product such as a boot for a universal joint, which causes a catch in the protruding direction when the molded product is released from the mold. Regarding improvement. In the present specification, the bellows-shaped product includes a tubular body having one or more steps of different diameters or constrictions.

[0002]

[Prior Art]

 When a bellows-shaped cylindrical product such as a boot for a constant velocity joint for automobiles (CVJ boot) is molded by an injection molding mold, conventionally, for example, a mold as shown in FIG. 3 (A) or (B) is used. Is being done. This mold is composed of outer dies 101 and 101 which are split molds which can be divided into at least two parts, and a core die 103 which forms a cavity 102 having the same shape as the product therein. The core mold 103 is provided with a protruding rod 104 protruding in the longitudinal direction from the tip of the core mold 103 in order to facilitate the removal of the molded product, and a gap between the protruding rod 104 and the core mold 103. An air blowing mechanism that blows out compressed air when protruding from S is formed. The compressed air blown out from the gap S along with the movement of the projecting rod 104 lifts the molded product from the core mold 103 and pushes it in the projecting direction. As a result, compressed air is turned to the large diameter side (rear end side) of the boot while the tip of the boot is projected and projected by the rod 104, and the boots are blown off by the pressure to be taken out from the core mold 103.

[0003]

[Problems to be solved by the device]

 However, according to this conventional molded product take-out method, the blowout portion of the compressed air is concentrated at one point on the tip of the core mold 103, so the compressed air blown out is between the molded product and the core mold 103. Before flowing back through the generated gap and reaching the large diameter side, pressure concentrates on the thin gate part at the boundary between the molded product and the runner or on the thin part of the molded product itself, and before that part release. May be damaged.

In particular, this is a problem when injecting synthetic resin. Since synthetic resin is generally harder than rubber, it has a problem that it is difficult to deform (swell). Moreover, since it is injection molding, it must be molded into the final product shape itself. Therefore, in the case of a bellows-shaped molded product in which a catch is generated in the protruding direction, it is difficult to remove the molded product from the core mold 103, unlike the blow molding. That is, the valley portion of the molded product cannot be taken out unless it gets over the crest portion of the core mold 103, and it cannot be taken out if it does not swell considerably. Therefore, in the case of a synthetic resin that is generally harder than rubber, it is taken out. However, it was difficult to obtain a product with a large difference in the mountain valleys.

An object of the present invention is to provide an injection-molding die in which a molded product can be easily taken out even if it is a bellows-shaped product.

[0006]

[Means for Solving the Problems]

 In order to achieve such an object, the present invention provides an injection molding die which comprises an outer die and a core die, and which has a projecting rod in the core die and discharges a fluid for ejecting from the inner side of the core die. The core die is composed of a plurality of core pieces divided in the moving direction of the protruding rod, and the core pieces are supported by the protruding rods so that the core pieces can move in the protruding direction, and at the time of protruding movement of the protruding rod. The core piece and the projecting rod are provided with a step portion in which the core piece abuts at a different position for each core piece so that the projecting fluid can be discharged from the gap formed between the core pieces as necessary. There is.

[0007]

[Action]

 Therefore, in order to remove the molded product from the core die after injection molding, the ejection fluid is supplied into the core die while ejecting the ejection rod. Along with the movement of the projecting rod, a gap is created in the moving direction (axial direction) between the core piece fixed to the tip of the projecting rod and the core piece of the next stage, and the projecting fluid such as compressed air is generated from this gap. Is blown out. Further, as the ejecting rods are ejected, the steps of the ejecting rods abut the corresponding core pieces and eject them one by one.Therefore, gaps are formed between the adjacent core pieces, and The ejecting fluid is blown out if necessary. For this reason, the projecting fluid is blown out from the vicinity of the peaks or valleys of the molded product, and instantaneously evenly projects into the entire molded product and the projecting fluid wraps around the surface of the molded product. Then, coupled with the protrusion by the protrusion bar, the molded product is separated from the core mold by fluid pressure.

On the other hand, the core piece after releasing the molded product is sequentially brought into close contact with the core piece fixed to the tip of the projecting rod by retracting (retracting) of the projecting rod, thereby forming a core mold without a gap. Suru Then, it is inserted into the outer mold again.

[0009]

【Example】

 Hereinafter, the configuration of the present invention will be described in detail based on the embodiments shown in the drawings. It should be noted that this embodiment is applied to a boot for a constant velocity joint having a large-diameter cylindrical portion and a small-diameter cylindrical portion at both ends of a bellows-shaped body portion having a conical shape as a whole.

FIG. 2 shows an embodiment of the injection molding die of the present invention. This injection molding die is composed of a divisible outer mold 1, a core mold 3 that forms a cavity 2 having the same shape as the molded product 18 between the outer mold 1, and a core mold with a tip portion. 3 and a projecting rod 4 that is provided so as to project in the core die 3 and to be movable in the direction.

The outer mold 1 is generally composed of at least two divided molds, and a sprue 13, a runner 14, and a gate 15 are formed on the small diameter side of the cavity 2.

The core die 3 is composed of a plurality of core pieces 5, 5, ..., 5 divided in the protruding direction of the protruding rod 4. The core pieces 5, 5, ..., 5 are fitted and supported by projecting rods 4 arranged in the center so as to be movable in the axial direction. The core pieces 5, 5, ..., 5 on the side of the small diameter portion on which the gate 15 is provided are attached to the tip of the projecting rod 4 by, for example, tightening screws 16 and move together with the projecting rod 4. Further, the core piece 5 on the large-diameter side rear end is fixed to a core-type supporting member (not shown), and is fixed at a fixed position regardless of the movement of the projecting rod 4. Further, the core pieces 5, 5, ..., 5 other than the core pieces on both ends are protruded only when they come into contact with the step portions 6, 6 ,. It is provided to work with. The core pieces 5, 5, ..., 5 are divided so that gaps 7, 7, ..., 7 are formed between the front and rear core pieces 5, 5 when the projecting rod 4 is projected. ing. For example, in the case of the present embodiment, the dividing surface 17 is a conical dividing surface 17a that is inclined at an angle of about 45 ° with respect to the protruding rod 4 at the slope 12 near the valley portion 11, and a radial dividing surface 17b. And a cylindrical dividing surface 17c in the axial direction and a dividing surface 17d in the radial direction. Each of the core pieces 5, 5, ..., 5 is provided so as to be movable in the axial direction with the axially dividing surface 17c of the core piece 5 in the preceding stage as a guide surface. Further, the projecting rod 4 is formed so that the core pieces 5, 5, ..., 5 have different diameters, and the diameter gradually increases toward the rear end side from the front end. Therefore, by changing the length of each step, the size of the gap 7 and the protrusion amount by the core piece 5 when the core pieces 5, 5, ... 5, ..., 5 can be changed. For example, in order to increase the protruding amount of the part that is difficult to release (part of the molded product), it is effective when the molded product is mechanically pulled out by partially setting the moving amount of the core piece 5 large. is there. Further, a vent hole 8 is provided in the axially dividing surface 17c of each core piece 5, 5, ..., 5 for allowing a fluid for projecting, for example, compressed air to pass therethrough. In the present embodiment, the vent holes 8 are provided in all the core pieces 5, 5, ..., 5 but are not limited to this and may be provided in any piece as required. is there. A vent passage 9 is provided between the projecting rod 4 and the core pieces 5, 5, ..., 5 for introducing a mold releasing fluid such as compressed air. Air is blown into the cavity 2 from the gaps 7, 7, ..., 7 generated when the pieces 5, 5, ..., 5 are projected through the vent holes 8 of the core pieces 5, 5, ..., 5 respectively. An air blowing mechanism is configured.

It should be noted that the above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, the product to which the present invention is applied is not particularly limited to the boot shown in the drawings, and a bellows-like product having the same diameter at both ends or a bellows-like product having at least one or more different diameters or constrictions or a fluid It can be applied to all products that need to eject a molded product with an ejection rod while ejecting with a blowout. Further, the core pieces 5, 5, ..., 5 are divided for each mountain forming the bellows part of the molded product, but the invention is not particularly limited to this, and one mountain is divided into three or more. Alternatively, it may be divided into two or more mountains. In addition, as in the present embodiment, the dividing position is such that when dividing at the slope portion 12 which is slightly displaced from the valley portion 11, burrs do not occur in the valley portion of the molded product and the performance of the boot product is not affected. However, the product is not particularly limited to this, and in the case of a product that does not cause a problem even if burrs are generated in the valley or the peak, the product may be divided by the valley 11 or the peak 10. However, division of the mold at or near the mountain portion 10 reduces the thickness of the mold, which easily causes deformation of the mold. Further, in the case of dividing at the inclined surface portion 12 as in this embodiment, there is an advantage that burrs are difficult to occur because the dividing surface is closed by receiving the injection pressure of the molten material at the time of injection molding.

According to the injection molding die of the present invention configured as described above, the bellows-shaped molded product is taken out from the core mold 3 as follows.

A molded product 18 having a desired shape obtained by injecting an injection material such as a synthetic resin from a nozzle of an injection molding machine into a cavity 2 between an outer mold 1 and a core mold 3 housed inside the outer mold 1 is formed. After the outer die 1 is divided and taken out from the outer die 1 together with the core die 3, it is detached from the core die 3 by ejecting the protruding rod 4. By the protrusion of the projecting rod 4, not only the core piece 5 at the front end but also the core pieces 5, 5, ..., 5 thereafter are also sequentially pushed out against the stepped portion 6 of the projecting rod 4, and the core mold 5 is formed. , 5, ..., 5 are divided in the axial direction, and the fluid for projecting is blown out from the gap 7 between the adjacent core pieces 5, 5. This movement depends on the ejecting speed of the ejecting rod 4, but normally the momentary ejecting of the ejecting rod 4 pushes the molded product 18 in the axial direction and the core pieces 5, 5, ..., 5 as well. As a result, the valleys of the molded product 18 are also extruded forward, and a force for taking out the molded product 18 from the core mold 3 is applied. At the same time, since the fluid pressure is uniformly applied to the entire area of the molded product 18, the molded product 18 is deformed and is blown off over the mountain portions 10, 10, ..., 10 of the core pieces 5, 5, ..., 5. ..

[0016]

[Effect of the device]

 As is clear from the above description, the injection molding die of the present invention is composed of a plurality of core pieces that project from the core die and are divided in the moving direction of the rod, and the core pieces protrude from the protruding rod. It is supported so that it can move in the pull-out direction, and a step portion is provided so that the core piece and the protruding bar abut at different positions for each core piece when the protrusion bar moves out. Since the ejecting fluid is discharged from the gap generated at the time as necessary, the stepped portions of the ejecting rods abut the corresponding core pieces as the ejecting rods eject and move, and these are sequentially pushed out, The mold can be divided into a plurality of parts in the projecting direction, and the projecting fluid can be blown out from each of the divided gaps as needed, so that the molded product can be blown off instantly and uniformly around the entire molded product. That is, the protrusion of the protrusion bar causes the core piece to protrude in the vicinity of each valley or mountain portion of the molded product, so that the molded product is easily separated from the core mold by fluid pressure.

Therefore, the high pressure does not concentrate and act on a part of the molded product, and the molded product is blown off and released from the mold with a uniform pressure. In particular, even in the case of a bellows-shaped product formed of a synthetic resin material that is difficult to deform, it is possible to increase the amount of protrusion at a portion where it is difficult to partly release, so that it is easy to take out.

[Brief description of drawings]

FIG. 1 is a central longitudinal cross-sectional view showing an embodiment of a core die, showing a molded product taken out.

FIG. 2 is a central longitudinal sectional view showing an embodiment of the injection mold of the present invention.

3A and 3B are explanatory views showing an example of a conventional injection molding die.

[Explanation of symbols]

 1 Outer mold 3 Core mold 4 Protruding rod 5 Core piece 6 Stepped portion of the protruding rod 7 Gap between core pieces 8 Vent hole 9 Vent passage for supplying fluid for ejecting

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display area B29L 31:24 4F

Claims (1)

[Scope of utility model registration request] 1. An injection molding die comprising an outer die and a core die, wherein a projecting rod is provided in the core die and a fluid for ejecting is ejected from the inside of the core die. It is composed of a plurality of core pieces divided in the moving direction of the projecting bar, and is supported by the projecting bar so that each of the core pieces can move in the projecting direction and at the time of projecting movement of the projecting bar. An injection characterized in that a step portion in which a piece and a projecting rod abut on each core piece at different positions is provided, and the projecting fluid is discharged from a gap formed between the core pieces as necessary. Mold for molding.