JPH0767715B2 - Hot runner type synthetic resin mold - Google Patents

Description

The present invention relates to a hot runner type synthetic resin mold using a heater pot.

[Conventional technology]

In the injection molding machine for synthetic resin, as shown in FIGS. 2 and 3, the upper mold 1 is mounted on the fixed plate A, while the lower mold 11 is mounted on the movable plate B, and the upper mold 1 and the lower mold 11 are connected to each other. The cavity 10 is formed, the upper mold 1 is provided with the spool S continuous with the resin filling nozzle,
In general, a runner R and a gate G are provided between the spool S and the cavity 10, and the cavity 10 is filled with the molten resin from the nozzle through the spool S, the runner R, and the gate G. (For example, Japanese Patent Laid-Open No. 49-29350 and Japanese Utility Model Publication No. 5
In recent years, as a synthetic resin product having a very thin wall thickness and a limited gate position, a branch path is provided in the upper mold, and a heater pot for heating and supplying molten resin is provided at the tip of the branch path. A hot runner type (valve gate type) in which the cavity is filled with molten resin directly from the nozzle of the heater pot, and after filling the molten resin, the valve pin inserted into the heater pot is lowered to close the nozzle and the spool and runner are omitted Also called)
Has also been used.

[Problems to be Solved by the Invention]

In the former molding die among the injection molding dies described in the prior art, the molten resin filled in the cavity from the nozzle is filled through the spool, the runner and the gate, so that the filling takes time. There is a problem that a spool, a runner, and a gate are also formed for each injection molding.

In the latter mold, since the molten resin is directly filled into the cavity from the heater pot nozzle, the molten resin can be filled in a short time from the former mold. Since it is necessary to form a nozzle, there is a problem that it requires a high degree of skill in processing the nozzle, and the nozzle is easily damaged by the valve pin that is blocked after passing or filling the molten resin, and this damage easily causes product defects. There was a problem.

The present invention has been made in view of such problems of the prior art, and an object thereof is to separately form a nozzle continuous with a cavity into a removable valve seat piece, It is an object of the present invention to provide a hot runner type synthetic resin mold which can be easily replaced according to the size of the cavity or when it is damaged.

[Means for Solving the Problems]

In order to achieve the above object, the hot runner type synthetic resin mold of the present invention forms a cavity in the first plate forming the upper mold, and at least from the large diameter mouth portion and the small diameter mouth portion and the ship bottom portion. With a large stepped gate opening,
A valve seat piece is exchangeably attached and fixed to the gate port, and a nozzle formed in the valve seat piece is opened and closed by reciprocating movement of a valve pin that is inserted into a heater pot.

It is also possible to attach and fix the valve seat piece fitted into the gate opening in a non-separable manner by a piece pushing plate fitted into the large-diameter opening portion of the gate opening.

[Action]

A gate opening is formed in a large size and in a step shape, a valve seat piece is exchangeably attached and fixed to the gate opening, and a nozzle continuous with a cavity and a resin path of a heater pot is bored in the valve seat piece. Therefore, even if the nozzle is damaged, only the valve seat piece can be removed and replaced. Moreover, since the lower part of the stepped gate mouth forms the bottom of the ship and the bottom of the valve seat piece is inserted into the bottom of the ship, the valve seat piece can be mounted accurately and stably.

Further, by fixing the valve seat piece fitted and inserted in the gate opening with the piece push plate, the valve seat piece can be more strongly mounted.

〔Example〕

The basic structure of the hot runner type synthetic resin mold according to the present invention will be described below with reference to FIGS. 1 and 2. 1 is an upper mold attached to a fixed plate A of an injection molding machine, and 11 is a movable plate B. In the lower mold, a cavity 10 is formed at the joint between the upper and lower molds 1 and 11, or a cavity is formed between the first plate 21 that constitutes the upper mold 1 and the first plate 31 that constitutes the lower mold 11. 10 is formed, the spool S and the branch passage 9 communicating with the spool S are formed in the upper mold 1, and the heater pot 2 for heating and supplying the molten resin is attached to the tip of each branch passage 9.

As shown in FIG. 4, the heater pot 2 penetrates the resin passage 4 in the central portion of the main body 3, attaches the lid body 13 to the rear portion of the main body 3, and
The valve pin 5 is reciprocally inserted into the resin passage 4 from the center of the main body 3, and the main body 3 is tapered at the lower part of the barrel 3a.
3b is formed, a branch pipe 9a communicating with the resin passage 4 and the branch passage 9 is provided in the lid body 13, the valve pin 5 has a tapered valve portion 5a at the tip, and the valve pin 5 protruding outward from the lid body 13 is formed. A piston 15 is attached to the rear part.

The piston 15 is inserted into a cylinder 12 provided in the upper mold 1 and can be reciprocated by air control.

On the first plate 21 of the upper mold 1 forming the cavity 10,
A large stepped gate opening 8 continuous to the cavity 10 is provided, the valve seat piece 6 is exchangeably fixed to the gate opening 8, and the valve seat piece 6 is provided with a nozzle 7 continuous to the resin passage 4 of the heater pot 2. The nozzle 7 is opened and closed by the reciprocating movement of the valve pin 5.

The stepped gate opening 8 formed in the first plate 21 is formed of at least a large diameter opening 8a, a small diameter opening 8b, and a ship bottom 8d so that the diameter gradually decreases toward at least the cavity 10.

The valve seat piece 6 attached to the stepped gate opening 8 includes a ship bottom body 6a fitted into the ship bottom 8d of the gate opening 8, a collar 6b protruding from an upper portion of the body 6a, and a nozzle bored therein. 7, the nozzle 7 is tapered from the resin passage 4 of the heater pot 2 toward the cavity 10.

The nozzle 7 is formed according to the size of the cavity 10, the type of synthetic resin, the filling pressure of the resin, and the like, and is formed so as to match the inclination angle θ of the valve pin valve portion 5a, and the valve pin 5 is lowered. At this time, it is desirable that the pin valve portion 5a be closed in close contact with the nozzle 7, but the tip of the pin valve portion 5a may move in and out of the cavity 10 from the nozzle 7 to some extent. Further, the tip of the valve seat piece 6 is mounted so as to slightly project into the cavity 10, the ship bottom body portion 6a bites into the surface layer of the product, and the navel of the product formed by the nozzle 7 is not exposed from the outer surface of the product. It is desirable to do so.

In the synthetic resin mold shown in FIG. 6, the stepped gate opening 8 has a large diameter opening 8a.
And a medium diameter mouth portion 8c, a small diameter mouth portion 8b, and a ship bottom portion 8d,
A guide path 6c having the same diameter as that of the resin path 4 is provided above the nozzle 7 formed in the valve seat piece 6, and the small-diameter opening 8b of the gate opening 8 extends to the bottom of the ship.
8d is fitted with the bottom portion 6a of the valve seat piece 6, the flange 6b of the valve seat piece 6 is inserted into the medium diameter opening 8c of the gate opening 8, and the piece pushing plate 16 is fitted into the large diameter opening 8a. Bolt N screwed into the first plate 21 from the push plate 16
The valve seat piece 6 is attached irremovably.

In the synthetic resin mold shown in FIGS. 8 and 9, the throttle portion 4a continuous with the resin passage 4 is formed as a separate body, and the throttle portion 4a is attached to the tip portion 3b of the heater pot body 3.

〔The invention's effect〕

Since the present invention is configured as described above, it has the effects described below.

A gate opening connected to the cavity is provided in a large and stepped manner, a valve seat piece having a nozzle formed in the gate opening is exchangeably fixed, and the nozzle is opened and closed by reciprocal movement of a valve pin inserted into the heater pot. Therefore, even if the nozzle is damaged by foreign matter mixed in the molten resin or the valve pin, it is only necessary to disassemble the upper mold and repair or replace only the valve seat piece. That is, even if the nozzle is damaged, it is not necessary to replace the upper mold, and only the valve seat piece needs to be replaced. Therefore, repair and replacement are extremely simple and easy, and repair and replacement costs are significantly low.

Also, since the valve seat piece is mounted and fixed to the gate port and the cavity is filled with molten resin, the valve seat piece is made of heat-resistant metal or metal that easily dissipates heat, and the nozzle is highly accurate. Not only can it be machined, but since the valve seat piece can be selected and fitted, the amount of molten resin can be adjusted by replacing the valve seat piece.

In particular, since the lower part of the gate opening forms the bottom of the ship, and the bottom of the valve seat piece is inserted into the bottom of the ship, the valve seat piece can be mounted accurately and in a stable state. By fixing the seat piece with the piece push plate, the valve seat piece can be mounted more strongly.

The resin mold of the present invention can also be applied to blow molding.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view of a hot runner type synthetic resin mold according to the present invention, FIG. 2 is a partially cutaway side view showing a usage example of a conventional injection molding mold, and FIG. 3 is a conventional injection molding mold. FIG. 4, FIG. 4 and FIG. 5 are main-part cross-sectional views showing an example of using a heater pot, FIG. 6 is a main-part cross-sectional view of an upper die showing an example of mounting a valve seat piece, and FIG. FIG. 8 and FIG. 9 are vertical sectional views showing essential parts of an example of using the similar type valve seat piece. 1 ... Upper mold, 11 ... Lower mold, 21,31 ... First plate, 2 ... Heater pot, 3 ... Main body, 3a ... Cylinder body, 3b ...
… Tip part, 4… Resin path, 4a… Throttling part, 5… Valve pin, 5a… Valve part, 6… Valve seat piece, 6a… Ship bottom body part, 6b…
… Tsuba, 6c… Guideway, 7… Nozzle, 8… Gate opening,
8a ... large diameter mouth, 8b ... small diameter mouth, 8c ... medium diameter mouth, 8d ... ship bottom, 9 ... branch, 10 ... cavity, 12 ... cylinder, 13 ... lid, 15 ... ... Piston, 16 ... piece push plate, A ... fixed plate, B ... movable plate, G ... gate, R ... runner, S ... spool, N ... bolt, θ ... pin valve part and gate Tilt angle

Claims (4)

[Claims] 1. A cavity (10) from a heater pot (2).
In a synthetic resin mold in which molten resin is directly filled in, the gate opening (8) provided in the cavity (10) of the upper mold (1) is made larger, and the diameter is gradually reduced stepwise toward the cavity (10). A small seat (8a), a small mouth (8b), and a ship bottom (8d), and a valve seat piece (6) is replaceably inserted into the gate opening (8). A hot runner type synthetic resin mold in which a nozzle (7) formed in a piece (6) is opened and closed by reciprocating movement of a valve pin (5) which is inserted into a heater pot (2). 2. A first plate (2) constituting an upper mold (1).
A cavity (10) and a stepped gate opening (8) are formed in 1), and a valve seat piece (6) attached to the gate opening (8) is fitted into the bottom (8d) of the gate opening (8). The bottom of the ship (6a),
The hot runner type synthetic resin mold according to claim 1, which is formed by a collar (6b) protruding outward from an upper portion of the body (6a) and a nozzle (7) bored inside. 3. A valve seat piece (6) fitted into the stepped gate opening (8) is separated by a piece pushing plate (16) fitted into the large diameter opening portion (8a) of the gate opening (8). The hot runner type synthetic resin mold according to claim 1 or 2, which is mounted and fixed irreversibly. 4. The hot runner type according to claim 1, 2 or 3, wherein the tip of the valve seat piece (6) mounted on the stepped gate port (8) is slightly projected into the cavity (10). Synthetic resin mold.