JPH0643080B2 - Mold structure for resin molding - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement in a combined structure of a resin molding die and a bolster (die holding device).

(Prior Art) Generally, a resin molding die structure is obtained by combining the dies mounted on the fixed side and movable side bolsters, respectively, on the dividing surface to melt the molten resin in the cavity formed in the die. It is molded by press-fitting at high pressure.

Since the press-fitting is performed at a high pressure in this way, the finished dimensions of the product do not appear if the mold is deformed by the injection pressure or holding pressure into the mold cavity.Thus, make the mold thicker and give it rigidity. Prevents mold deformation.

For this reason, the mold becomes large, and the weight is usually 100 kg or more, so not only the manufacturing cost is high, but also the replacement work such as mounting and dismounting the mold on the bolster fixed to the molding machine can be performed manually. There wasn't.

Also, when positioning by combining the fixed side and movable side molds during injection molding, the guide posts protruding from the fixed side mold are fitted to the guide bushes attached to the movable side mold to perform positioning. is doing.

Conventional guide posts include a straight columnar shape and a tapered frustoconical shape, but the mold and bolster repeatedly increase and decrease in temperature when production is started, and the volume expands and contracts. For this reason, in the case of a straight columnar member, the gap may gradually increase due to sliding friction, the combination of the molds may shift, and the resin may leak from the split surface.

When molding a product with a large number of through holes such as connectors, a large number of core pins for through hole molding are projected on the mold. On the other hand, since the gap between the guide post and the guide bush is large immediately before positioning, the core pin of the die to be fitted first before this fitting is displaced from the pin hole and collides and breaks. In many cases, the cavity in which the core pin is broken cannot be used, and there is a problem that the operating rate decreases.

(Problems to be Solved by the Invention) The present invention eliminates the above-mentioned drawbacks and pre-applies a stress generated by the deformation of the bolster to the inner mold, thereby enhancing the rigidity of the mold and preventing the deformation. The mold is miniaturized to facilitate the manufacture and transportation, and the workability is improved by facilitating the mounting and replacement on the molding machine.

Further, according to the present invention, the movable side mold has a floating structure, and the combined structure of the guide post and the guide bush is improved to improve the positioning accuracy and prevent breakage of the core pin to improve the operating rate. It is intended.

(Means for Solving the Problems) The present invention has a structure in which a wedge-shaped preload cotter is interposed between the side surface of the mold attached to the fixed bolster and the inner wall of the bolster, and the external force applied at the time of injection or more The first gist is to add the internal stress of

Further, according to the present invention, the base end side of the guide post projecting on the dividing surface of the fixed side mold is formed of a truncated cone and the tip side is formed of a cylindrical body, and the guide side of the movable side mold is The guide bush embedded in the dividing surface and detachably fitted to the guide post is provided with a tapered portion on the inner surface at the distal end side that is in sliding contact with the truncated cone of the guide post, and the proximal end side is a cylindrical body. This is the second gist.

Furthermore, the present invention immerses the fixed side mold from the dividing surface of the bolster, projects the movable side mold from the dividing surface of the bolster, and forms a tapered surface on the side surface of the protruding mold.
A locking plate with a tapered surface that abuts this tapered surface is provided on the side surface of the fixed mold, and a wedge-shaped preload cotter is interposed between the outside of this locking plate and the inner wall of the bolster, and it is movable. The third gist is that the side mold is loosely fitted inside the bolster with a gap.

(Operation) Next, the operation of the present invention will be explained. By interposing a wedge-shaped preload cotter between the die and the inner wall surface of the bolster, the die and the bolster are integrally configured to improve rigidity. The structure is such that the entire external stress applied to the cavity is received.

Further, by interposing a wedge-shaped preload cotter, the bolster is deformed, and the stress generated thereby is applied to the inner die in advance. The magnitude of this stress is such that an internal stress larger than the external force applied to the cavity at the time of injection is added to prevent deformation of the mold due to external force such as injection pressure or holding pressure applied at the time of injection.

In addition, the movable side mold according to the second aspect of the present invention has a floating structure, the base end side of the guide post is a straight cylindrical body, and the tip side is a taper portion. Even if the relative position is deviated, since the movable mold has a floating structure, the guide post can be smoothly inserted into the guide bush and positioned accurately.

Moreover, since the straight cylindrical body is inserted first and positioned roughly to prevent breakage of the core pin, the tapered portion can be fitted and positioned accurately.

A third aspect of the present invention is to provide a locking plate having a tapered surface on a side surface of a fixed-side mold so that the movable-side mold is allowed to be immersed in the divided surface of the bolster. When the movable die is combined with the fixed die, the protruding taper surface of the movable die is sandwiched by the locking plate on the fixed side. Then, the cotter supports the fixed-side bolster in which compressive stress is generated, and internal stress is applied to the movable-side mold as well as the fixed-side mold.

(Example) Hereinafter, the present invention will be described in detail with reference to the examples shown in the drawings.

1 and 2 show an embodiment of the present invention.
In the figure, 1A is a fixed side bolster, 1B is a movable side bolster, a fixed side mold 2A is mounted inside the fixed side bolster 1A, and a movable side mold 2B is mounted inside the movable side bolster 1B. .

A wedge-shaped preload cotter 4 is interposed between the upper surface of the fixed-side mold 2A and the inner wall surface 3A of the fixed-side bolster 1A and is greater than the external force applied to the fixed-side mold 2A from the vertical direction during injection. Internal stress is added.

Further, a cylindrical guide post 6 is provided on the dividing surface 5A of the fixed side bolster 1A and the fixed side mold 2A mounted inside this.
6 is projected.

Further, guide bushes 7 and 7 into which the guide posts 6 and 6 are fitted are embedded in the movable side bolster 1B and the dividing surface 5B of the movable side mold 2B mounted inside thereof.

In the figure, 8 is a cavity formed in the fixed side mold 2A.

The mold structure having the above-mentioned structure is such that a wedge-shaped preload cotter 4 is interposed between the upper part of the stationary mold 2A and the inner wall surface 3A of the stationary bolster 1A as shown in FIG. Internal stress is applied to the mold 2A from the vertical direction.

Generally, the fixed-side mold 2A is gradually deformed by an external force such as an injection pressure for injecting the resin into the cavity 8 or a holding pressure applied after the injection is completed. Therefore, conventionally, the fixed-side mold 2A is made thicker. The fixed bolster 1A that has rigidity to prevent deformation and holds the fixed mold 2A is merely a function as a jig for attachment.

However, in the mold structure of the present invention, the fixed side mold 2A and the fixed side bolster 1A are integrated by interposing the wedge-shaped preload cotter 4 between the fixed side mold 2A and the fixed side bolster 1A. As a result, the rigidity is improved and the external stress applied to the inside of the cavity 8 is received as a whole.

Moreover, not only is the cotter 4 interposed to form an integral structure, but the fixed bolster 1A having a U-shaped cross section is deformed by driving the wedge-shaped cotter 4, and the stress generated thereby is applied to the inner fixed side. Mold 2A
Is added as an internal stress in advance. The magnitude of the internal stress to be added in advance depends on the cavity 8 at the time of injection.
Since a stress larger than the external stress applied inside is applied, even if the fixed-side mold 2A is formed thin, it is possible to prevent the fixed-side mold 2A from being deformed by an external force at the time of injection.

In other words, even if the fixed side mold 2A is made thin, it can be prevented from being deformed by an external force, so that the mold weight can be reduced to about 35 kg, which can be greatly reduced to about one-third of the conventional mold weight, and manufacturing cost and transportation The cost will be lower and the mold installation and replacement will be easier.

FIGS. 3 and 4 show another embodiment of the present invention, in which a wedge-shaped preloading cotter 4 is interposed between the upper part of the stationary mold 2A and the inner wall surface 3A of the stationary bolster 1A. The structure is the same as that of the above-mentioned embodiment in that the internal stress is applied from the vertical direction.

Further, a gap 9 of about 0.2 mm or less is formed between the upper and lower surfaces of the movable side mold 2B mounted inside the movable side bolster 1B and the inner wall surface 3B so that the movable side mold 2B is loosely fitted. It is held and has a floating structure.

Further, as shown in FIG. 4, the divided surface 5A of the fixed side mold 2A has a tapered portion 10A having an inclination of about 5/1000 toward the base end side.
The truncated conical body 11 is formed with a straight columnar body 12 on the front end side, and the guide post 6 provided with the tapered portion 13 is projectingly provided on the front end.

A guide bush 7 that is detachably fitted to the guide post 6 is embedded in the dividing surface 5B of the movable mold 2B. The guide bush 7 has a taper portion 10B which fits the taper portion 10A of the truncated cone 11 on the inner surface on the tip end side, and a straight cylindrical surface 14 into which the cylinder 12 is inserted on the inner surface on the base end side. Has been done.

Further, as shown in FIG. 3, a plurality of core pins 15 are projected on the projecting portion of the movable mold 2B, and pin holes 16 are formed in the cavity 8 of the fixed mold 2A which opposes the core pins 15. The core pin 15 penetrates the inside of the cavity 8 formed by combining the two molds 2A and 2B to form a through hole in the product.

In the mold structure having the above structure, when the movable mold 2B moves, the cylindrical body 12 at the tip of the guide post 6 is first inserted into the tapered portion 10B of the guide bush 7. At this time, even if the relative positions of the two molds 2A and 2B are deviated due to the interposition of the cotter 4 and the temperature change, the movable mold 2B has the floating structure with the gap 9 and is smoothly inserted.

When moving further, the cylindrical body 12 becomes a straight cylindrical surface 1
It is inserted in 4 and almost positioned. In this state, a plurality of core pins 15 ... Protruding on the movable side mold 2B are inserted into the pin holes 16 ... of the fixed side mold 2A to position this part first.

After this, when the movable mold 2B is further moved, as shown in FIG. 4, the taper portion 10A of the truncated cone 11 is fitted to the taper portion 10B of the guide bush 7, and the completion of fitting is several mm.
The resin leakage gap between the divided surfaces 5A and 5B can be suppressed to 0.01 mm or less in front.

Therefore, the movable side mold 2B has a floating structure, and the guide post 6 has a combination structure of the straight columnar body 12 for preventing the core pins 15 from being broken and the tapered portion 10A excellent in positioning accuracy, thereby improving the operating rate. The dimensional accuracy of the product can be improved.

In other words, in the conventional configuration, due to the wear and biting of the guide post, the mold with dozens of core pins often breaks, and the resin leaks from the dividing surface, so the accuracy of the product could not be obtained. With the configuration of the present invention, these problems can be solved.

FIG. 5 and FIG. 6 show another embodiment of the present invention, in which the stationary mold 2A is attached to the dividing surface 5 of the stationary bolster 1A.
Immerse yourself from A and move the movable mold 2B to the movable bolster 1.
It is made to project from the split surface 5B of B.

Locking plates 18, 18 having tapered surfaces 17A are provided on the upper and lower surfaces of the stationary mold 2A, and a wedge-shaped preloading cotter 4 is provided on the upper surface of the upper locking plate 18 to provide a stationary bolster. It is installed in 1A.

A tapered surface 17 that contacts the tapered surface 17A of the locking plate 18 is provided on the upper and lower surfaces of the movable mold 2B that protrude from the split surface 5B of the movable bolster 1B.
B and 17B are formed, and this mold 2B is loosely fitted to the bolster 1A with a gap 9 provided inside.

When the movable mold 2B having a floating structure is moved, the taper surfaces 17B formed on the upper and lower surfaces of the movable mold 2B protruding from the movable mold 2B are locked to the locking plate provided on the fixed bolster 1A. 18 tapered faces 1
7A and 17A are contacted and sandwiched from above and below, and are supported by the fixed side bolster 1A in which compressive stress is generated by the cotter 4, and internal stress is also applied to the movable side mold 2B.

Therefore, like the fixed-side mold 2A, an internal stress larger than the external force applied to the cavity 8 at the time of injection is applied to the movable-side mold 2B as well, so that even if the movable-side mold 2B is formed thin. It is possible to prevent the deformation of the mold due to the external force at the time of injection.

In the above embodiment, the case where the compressive stress is applied to the mold in the vertical direction has been described, but the structure may be applied in the lateral direction.

(Effects of the Invention) As described above, according to the resin molding die structure of the present invention, the internal stress is applied in advance to the mold held inside by the stress generated by the deformation of the bolster. The rigidity can be increased to prevent deformation, the mold can be downsized, manufacturing and transportation can be facilitated, and workability such as installation and replacement in a molding machine can be improved.

Further, according to the present invention, the movable side mold has a floating structure, and the combination structure of the guide post and the guide bush is improved to improve the positioning accuracy and prevent breakage of the core pin to improve the operating rate. it can.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention.
FIG. 1 is a longitudinal sectional view of a resin molding die structure, and FIG. 2 is a first sectional view.
FIG. 3 is a perspective view showing a fixed side mold and a movable side mold, FIG. 3 is a longitudinal sectional view of a mold structure according to another embodiment of the present invention, and FIG. 4 shows a fitted state of a guide post and a guide bush. Cross section,
FIG. 5 is a longitudinal sectional view of a mold structure according to another embodiment of the present invention, and FIG. 6 is a perspective view showing the fixed side mold and the movable side mold of FIG. 1A: fixed side bolster 1B: movable side bolster 2A: fixed side mold, 2B: movable side mold 3A, 3B ... inner wall surface, 4 ... cotter 5A, 5B ... split surface, 6 ... Guide post 7 ... Guide bush, 8 ... Cavity 9 ... Gap, 10A, 10B ... Tapered part 11 ... Frustum cone, 12 ... Cylindrical body 15 ... Core pin, 7A, 17B ... Tapered surface 18 ... Locking plate

Claims (3)

[Claims] 1. A preload cotter having a wedge shape is interposed between a side surface of a mold attached to a fixed bolster and an inner wall of the bolster to apply an internal stress more than an external force applied during injection. Characteristic resin mold structure. 2. A movable-side mold, wherein a base end side of a guide post projecting from a divided surface of a fixed-side mold is formed of a truncated cone and a tip end is formed of a cylindrical body. Of the guide bush, which is embedded in the divided surface of the guide post and which is detachably fitted to the guide post, has a tapered portion slidably contacting the truncated cone of the guide post, and the base end side is a cylindrical body. The mold structure for resin molding according to claim 1, wherein: 3. A fixed side mold is immersed in the divided surface of the bolster, a movable mold is protruded from the divided surface of the bolster, and a tapered surface is formed on the side surface of the protruding mold, and this tapered surface is formed. A locking plate with a tapered surface that abuts against the fixed mold is provided on the side surface of the fixed mold, and a wedge-shaped preload cotter is interposed between the outside of the locking plate and the inner wall of the bolster, and the movable mold is A mold structure for resin molding, characterized in that the mold is mounted in a loose fit inside the bolster.