JPH05200787A - Manifold device for hot runner mold - Google Patents

Abstract

PURPOSE:To prevent leakage of resin from the runner lying between a pair of manifold members to the outside of the manifolds in a two-piece type manifold. CONSTITUTION:On the contact surfaces of both manifold members 12, 13, recessed grooves 41, 42 are formed in a manner surrounding the entirely of a runner 18 from the outside. A core 43 is fitted therein across these recessed grooves 41, 42. A groove-shaped recession 45 is formed on the inside surface of the runner 18 side of the core 43. The material of both manifold members 12, 13 is HPM, and the material of the core 43 is brass. In coefficient of thermal expansion, brass is greater than HPM. Resin leaked into the interstice between the contact surfaces of both manifolds 12, 13 from the runner 18 stays in the recession 45. At this time, inner pressure is generated in the recession 45. Herein, the core expands greater than both manifold members 12, 13. Thus, respective surfaces of the core 43 are forced to abut against the corresponding surfaces in the recessed grooves 41,42. In this manner, an escape of resin to the outside of the manifold 11 can be prevented more positively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot runner mold manifold device used for injection molding of thermoplastic resins.

[0002]

2. Description of the Related Art A hot runner mold used for injection molding of a thermoplastic resin always keeps the plastic from the sprue and runner to the vicinity of the gate in a molten state in order to improve the molding efficiency. Further, in the hot runner mold, the runner is formed in the manifold containing the heater. Conventionally, there is a manifold in which a runner is punched in an integral member. By the way, when performing resin change such as color change during molding, it is sufficient to replace the resin in the sprue or the runner, but it may take time due to the retention of the resin in the runner. Therefore, a hot runner mold in which a pair of manifold members are separably joined to form a manifold and a runner is formed between both manifold members has been conventionally used so that the resin accumulated in the runner can be taken out.

Here, an example of a conventional hot runner die of this type will be described with reference to FIG. 4 schematically showing the construction thereof. In the figure, 1 is a fixed die, 2 is a movable die, and these fixed die 1 and movable die 2 move vertically with respect to each other to open and close. It is formed inside. The fixed mold 1 includes a fixed-side mold plate 4 forming an outer surface of a product, a fixed-side receiving plate 5 attached to a back surface (upper surface in the drawing) of the fixed-side mold plate 4, and an upper surface of the fixed-side receiving plate 5. Fixed side mounting plate 7 mounted on the fixed side platen of the injection molding machine via a spacer block 6 and a heater (not shown) provided between the fixed side mounting plate 7 and the fixed side receiving plate 5. Manifold with built-in 11
And so on. The manifold 11 is composed of a first manifold member 12 and a second manifold member 13 which are joined in the vertical direction in the figure. The manifold members 12 and 13 are bolts 14 screwed from the upper side in the figure.
Are fixed to each other and are separable.
Further, the fixed side mounting plate 7 is provided with a nozzle receiving portion 16 to which the nozzle of the injection molding machine is connected. on the other hand,
In the manifold 11, a sprue 17 communicating with the nozzle receiving portion 16 is vertically formed to penetrate the second manifold member 12, and a runner 18 branched from the sprue 17 is provided between the manifold members 12 and 13. It is formed on the joint surface (parting line surface). The final branch passage of the runner 18 penetrates the first manifold member 12 in the vertical direction and opens at the lower surface thereof. Further, a plurality of bushes 21 are embedded and fixed in the fixed side receiving plate 5 and the fixed side template 4. These bushes 21
The upper surface is in contact with the lower surface of the second manifold member 13, and the inside is in communication with the final branch passage of the runner 18, respectively. Each of the bushes 21 has a built-in spear 22, and the inside thereof communicates with a gate 23 formed in the stationary mold plate 4 and opening to the cavity 3. On the other hand, the movable mold 2 is
The movable side template 31 forming the inner surface of the product and the movable side template 31.
Movable side support plate 32 attached to the back surface (lower surface in the figure) of 31
And a movable side mounting plate 34 which is mounted on the lower surface of the movable side receiving plate 32 via a spacer block 33 and is mounted on the movable side platen of the injection molding machine. Along with this, between the movable side mounting plate 34 and the movable side receiving plate 32, there is provided a protruding plate 35 which moves up and down relative to the movable side mounting plate 34, and the protruding pin 36 is mounted on the protruding plate 35. Is fixed. These protruding pins 36
The movable side receiving plate 32 and the movable side template 31 are slidably pierced so that the front end is located facing the cavity 3. Then, at the time of molding, the molten resin is injected from the nozzle of the injection molding machine with the mold clamped. This resin flows from the sprue 17 through the runner 18 and the spear 22 into the cavity 3 from the gate 23. This cavity 3
After the resin filled therein is solidified, the mold is opened to take out the product which is the solidified resin in the cavity 3. At this time, the ejection pin 36 ejects the product to release it.

In the conventional hot runner mold manifold 11 shown in FIG. 5, both manifold members are used.
The joint surface of 12 and 13 is entirely flat,
Both manifold members 12 and 13 are in contact with each other outside the runner 18.

[0005]

However, in the above-mentioned conventional two-division type manifold 11, both manifold members 12,
Since the joint surface of 13 is entirely flat and both manifold members 12, 13 are in contact with each other on the outside of the runner 18, the resin is joined from the runner 18 to both manifold members 12, 13. There was a problem that it easily leaked to the outside through the surface.

The present invention is intended to solve such a problem and provides a manifold device of a hot runner mold which can prevent resin from leaking from the runner to the outside through the joint surface of the pair of manifold members. The purpose is to do.

[0007]

In order to achieve the above-mentioned object, the present invention comprises a first manifold member and a second manifold member which are separably joined to each other. In a hot runner mold manifold device in which a runner is formed between two runner members, a groove is formed on the joint surface portion between the first manifold member and the second manifold member by enclosing the runner as a whole from the outside. A nest made of a material having a coefficient of thermal expansion larger than those of the both manifold members is fitted into these concave grooves, and a concave portion is formed on the inner surface on the runner side of the nest. It was done.

[0008]

In the hot runner mold manifold device of the present invention, when resin leaks from the runner formed between the first manifold member and the second manifold member between the joint surfaces of both manifold members, The resin is fitted across the concave grooves of both manifold members and flows into and accumulates in the concave part formed on the inner surface on the runner side of the nest that surrounds the entire runner from the outside, and accumulates outside both manifold members. Does not leak. At the same time, due to the internal pressure generated by the resin flowing into the recess, the end surface and the outer surface of the insert are pressed against the corresponding surfaces in the recess groove, whereby the end surface and the outer surface of the insert and the recess groove are pressed. The resin is surely prevented from leaking to the corresponding surfaces, and the resin is further surely prevented from leaking to the outside of both manifold members. Furthermore, if both manifold members and the nest are heated by contact with resin,
A nest with a higher coefficient of thermal expansion expands more than both manifold members. As a result, each surface of the insert is pressed against the corresponding surface in the concave groove more reliably, and thus the resin is more surely prevented from leaking to the outside of both manifold members.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Since the hot runner mold of this embodiment has substantially the same structure as the conventional mold shown in FIG. 4 described above, the same parts are designated by the same reference numerals and the description thereof will be omitted. However, the different points will be mainly described. In this embodiment, the manifold 11 is composed of a first manifold member 12 and a second manifold member 13 which are also separably joined. And
In the joint surface portion of both the manifold members 12 and 13, the entire runner 18 is surrounded from the outside as shown in FIG.
42 are formed respectively. 1 and 2 of the insert 43 in the groove 41 of the first manifold member 12.
The lower half in the figure is fitted, and the upper half of the nest 43 is a rising portion 44 protruding from the first manifold member 12. The rising portion 44 is fitted in the concave groove 42 of the second manifold member 13. A groove-shaped recess 45 is formed on the inner surface of the rising portion 44 on the runner 18 side.
It is a resin reservoir space 46 between 13 parts. Further, the material of the both manifold members 12 and 13 is HPM (trade name of Hitachi Metals), whereas the material of the nest 43 is brass.
The coefficient of thermal expansion of brass is higher than that of HPM.

Next, the operation of the above configuration will be described. During molding, when molten resin leaks from the runner 18 formed between the first manifold member 12 and the second manifold member 13 between the joint surfaces of both manifold members 12 and 13, this resin is Between the members 12 and 13, the runner 18 as a whole is flowed and accumulated in the resin reservoir space 46 that surrounds the entire runner 18 from the outside. In this way, the resin is accumulated in the resin reservoir space 46, so that the resin is stored in the resin reservoir space 46.
Does not leak to the outside. At the same time, the resin is allowed to flow into the resin reservoir space 46 formed of the recess 45 formed on the inner surface of the insert 43 that is fitted across the recessed grooves 41 and 42 of both the manifold members 12 and 13. Due to this, an internal pressure is generated in the recess 45, and this internal pressure causes both end surfaces of the insert 43, that is, the upper and lower surfaces shown in FIGS.
The outer surface on the side is pressed against the corresponding surface in the recessed grooves 41, 42 of both manifold members 12, 13. This surely prevents the resin from leaking from the resin reservoir space 46 between the both end surfaces and the outer surface of the nest 43 and the corresponding surfaces in the concave grooves 41 and 42, and the resin leaks to the outside of the manifold 11. Is prevented more reliably. Further, both the manifold members 12 and 13 and the nest 43 are heated by contact with resin or the like. However, when heated in this way, the nest 43 made of a material having a larger thermal expansion coefficient than the both manifold members 12 and 13. Inflate greatly. This allows nesting 43
Will be more surely pressed against the corresponding surfaces in the grooves 41, 42. Therefore, it is possible to more reliably prevent the resin from leaking to the outside of the manifold 11.

The present invention is not limited to the above embodiment, and various modifications can be made. For example,
In the above embodiment, the material of the manifold members 12 and 13 is HP.
Although the material of the nest 43 is M and brass, the material is not limited to brass. That is, as the material for the manifold member and the nest, any material that is suitable as a mold material and has a coefficient of thermal expansion that is appropriately larger than that of the material for the manifold member may be used.

[0012]

According to the present invention, in a hot runner mold manifold device in which a runner is formed between a first manifold member and a second manifold member that are separably joined together, the two manifold members are joined together. On the surface,
Since the entire runner is surrounded from the outside to form recessed grooves, a nest is fitted in these recessed grooves across both recessed grooves, and a recess is formed on the inner surface on the runner side of this nest. Even if leaks from the runner between the joint surfaces of both manifold members, this leaked resin will collect in the recess of the nest, and
Due to the internal pressure generated by the resin flowing into the concave portion, the end surface and the outer surface of the insert are pressed against the corresponding surfaces in the concave groove, so that the resin can be reliably prevented from leaking to the outside of both manifold members. .. Further, since the material of the nest has a larger coefficient of thermal expansion than the material of both the manifold members, when the resin is heated by contact with the nest, the nest expands more than the both manifold members, so that The surface is more surely pressed against the corresponding surface in the groove, so that the resin can be more surely prevented from leaking to the outside of both the manifold members.

[Brief description of drawings]

FIG. 1 is a sectional view of the entire mold showing a first embodiment of a hot runner mold manifold device of the present invention.

FIG. 2 is a sectional view of the same manifold.

FIG. 3 is a plan view of the same first manifold member.

FIG. 4 is a sectional view of the entire mold showing an example of a conventional hot runner mold manifold device.

[Explanation of symbols]

 12 1st manifold member 13 2nd manifold member 18 Runner 41 Groove 42 Groove 43 Nest 45 Groove

Claims (1)

[Claims] 1. A hot runner mold in which a first manifold member and a second manifold member are separably joined to each other and a runner is formed between the first manifold member and the second manifold member. In this manifold device, a concave groove is formed in the joint surface portion between the first manifold member and the second manifold member so as to surround the entire runner from the outside, and these concave grooves extend over both concave grooves. A manifold device for a hot runner mold, characterized in that a nest made of a material having a coefficient of thermal expansion larger than that of the both manifold members is fitted, and a recess is formed on the inner side surface of the nest on the runner side.