JP2002113746A - Mold for hot-runner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for a hot-runner in which a resin can be prevented from being leaked at a connection part between a manifold and a nozzle and there exists no possibility of loading an excess load on a nozzle part even when the manifold is thermally expanded. SOLUTION: The base part 14a of a plurality of nozzle 14 which pass through a fixed side mold plate 7 and in which the apex opening part faces to the gate 18 of a cavity block 10 is fixed on the manifold 11 and a seal ring 31 is fitted on the apex outer peripheral face part of the nozzle 14 and a slide ring 32 provided with a hole 33 being brought into slide-contact with the outer periphery of this seal ring 31 is inserted into a recessed part 35 provided on the contacting face part between the fixed side mold plate 7 and the cavity block 10 so as to be freely slide in the transverse direction.

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 used for injection molding of a thermoplastic resin.

[0002]

2. Description of the Related Art In a hot runner mold, FIG.
As shown in the figure, the manifold 41 provided in the fixed die 40
The molten resin is injected into the cavity 43 from the gate 44 with the front end opening of the nozzle 42 communicating with the resin flow path 41 a facing the gate 44 of the cavity 43. Is fitted into the hole 46 provided in the fixed mold plate 45 so as to be positioned and fixed to the fixed mold plate 45. The bottom surface of the manifold 41 is slidably contacted with the top surface of the nozzle 42. The structure that touched
Widely adopted. 47 is a gate pin for opening and closing the gate 44, 48 is a cylinder for reciprocatingly driving the gate pin,
49 is a fixed-side mounting plate, and 50 is a movable-side mold plate.

However, in the hot runner mold having the above-described structure, when the manifold 41 thermally expands in the longitudinal direction indicated by the arrow Y, the nozzle 42 is connected to the manifold 41.
Since the manifold 41 slides along the top surface of the nozzle 42 and does not receive an excessive lateral load on the nozzle 42, the manifold 41 has an advantage that it is not fixed to the top surface of the nozzle 42. Since the bottom surface of the manifold 41 is only pressed against the resin, there is a problem that a gap is generated in the connecting portion 51 between the manifold and the nozzle due to the injection pressure of the resin, so that the resin leaks easily.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned conventional problems, and can prevent resin leakage at a connecting portion between a manifold and a nozzle.
An object of the present invention is to provide a hot runner mold in which an excessive load is not applied to the nozzle portion even when the manifold thermally expands.

[0005]

According to a first aspect of the present invention, there is provided a hot runner mold according to the first aspect, wherein a plurality of nozzles penetrate a fixed side mold plate and have a front end opening facing a gate of a cavity block. The base is fixedly mounted on a manifold, a seal ring is fitted to the outer peripheral surface of the tip of the nozzle, and a slide ring having a hole that slides on the outer periphery of the seal ring is joined to the fixed mold plate and the cavity block. It is characterized in that it is slidably fitted in a lateral direction into a concave portion provided in the surface portion.

[0006] In the present invention, the lateral direction refers to a direction orthogonal to the mold opening and closing direction.

According to the first aspect of the present invention, since the base of the nozzle is fixedly attached to the manifold, resin leakage from the connection between the manifold and the nozzle can be reliably prevented. In addition, the resin that has flowed out of the nozzle tip opening and filled the gap between the nozzle tip and the cavity block is sealed by the seal ring and the slide ring and is prevented from leaking into the nozzle receiving space of the fixed mold plate. . When the manifold thermally expands and the nozzle integrated with the manifold moves in the horizontal direction, the slide ring is also driven in the horizontal direction via the seal ring and slides in the recess in the horizontal direction. No excessive load is applied to the part. The expansion and contraction in the axial direction (the mold opening and closing direction) due to the thermal expansion of the nozzle is absorbed by the sliding of the seal ring and the slide ring in the mold opening and closing direction,
No excessive load is applied to the nozzle due to the above expansion and contraction.

In the present invention, the seal ring and the slide ring can be formed of various materials.
If at least one of the seal ring and the slide ring is made of a material having a lower thermal conductivity than the stationary mold plate and the cavity block, the high temperature nozzle can move the fixed ring to the stationary mold plate. This is preferable because heat conduction is suppressed, the temperature of the fixed mold plate can be prevented from increasing, and the cycle time of injection molding can be shortened. As the material having a low thermal conductivity, non-metallic materials such as various metals or ceramics can be used. Particularly, stainless steel is particularly preferable because machining is easy and the value of the thermal conductivity is low. .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to an example shown in FIGS. The hot runner mold 1 includes a fixed mold 2 and a movable mold 3. The movable mold 3 shows only a part of a movable mold plate 5 having a core block 4, and also does not show an ejector pin or the like. I have.
Reference numeral 6 denotes a fixed-side mounting plate, and 7 denotes a fixed-side die plate that is fastened to the fixed-side mounting plate 6 via a cylinder mounting plate 8 and a spacer 9. It is provided as nesting.

Reference numeral 11 denotes a manifold provided in the fixed mold 2, which is fixedly attached to the fixed mold plate 7 by bolts (not shown), 12 is a heat insulating spacer for positioning, and 13 is a heat insulating spacer for pressing down the manifold. Reference numeral 14 denotes a nozzle communicating with the resin flow path 11a of the manifold 11, and its base 14a is fixedly attached to the manifold 11 by bolts 15 (see FIG. 2). The nozzle 14 is fitted with a gap into a hole 16 formed in the fixed mold plate 7, and its tip opening faces the gate 18 at the entrance of the cavity 17. 19 is a heater of the nozzle 14. The manifold 11 also includes a heater for heating, but is not shown.

Reference numeral 20 denotes a gate pin having a central axis oriented in the mold opening and closing direction indicated by an arrow X, penetrates the manifold 11 and the nozzle 14, and opens and closes the gate 18 by its tip. The cylinder accommodated in the plate 8 is coaxially arranged in series with the gate pin 20, and the base end 20 a of the gate pin 20 is fixedly attached to the piston rod 22.

As shown in FIG. 2, reference numeral 31 denotes a seal ring made of stainless steel, the base of which is fitted and fixed to the outer peripheral surface of the distal end of the nozzle 14 (specifically, the outer peripheral surface of a cylindrical portion near the distal end opening), as shown in FIG. Are thin and constitute the seal lip 31a. Reference numeral 32 denotes a stainless steel perforated disk-shaped slide ring, which has a hole 3 slidingly contacting the outer periphery of the seal ring 31 (specifically, the seal lip 31a) at the center.
3 and a concave portion 35 formed between the short cylindrical concave hole 34 provided in the cavity block 10 and the fixed side mold plate 7 covering a part of the concave hole 34, in a lateral direction (arrow Y). (A direction orthogonal to the mold opening / closing direction). The depth of the concave hole 34 is slightly larger than the thickness of the slide ring 32, and the diameter thereof is smaller than the diameter of the slide ring 32 (for example, 1 to 2 mm).

To perform injection molding using the hot runner mold 1 having the above structure, the gate 18 is opened by driving the gate pin 20 by the cylinder 21 after the mold is closed, and the molten resin from the sprue portion 11b of the manifold 11 is removed. The resin is injected into the cavity 17 through the resin flow path 11a and the nozzle 14. After the injection, the gate 18 is driven by the cylinder 21 in the opposite direction to close the gate 18, and after a predetermined holding time, the mold is opened to take out the molded product.

During the above-described injection molding process, since the base 14a of the nozzle 14 is fixedly attached to the manifold 11, resin leakage from the connecting portion 36 between the manifold 11 and the nozzle 14 can be reliably prevented. . The resin that has flowed out of the opening at the tip of the nozzle 14 and filled the gap 37 (see FIG. 2) between the tip of the nozzle and the cavity block 10 is filled with the seal ring 31 and the slide ring 32.
Nozzle hole 1 of fixed side template 7 sealed by
6 is prevented from leaking.

When the manifold 11 thermally expands in the longitudinal direction, that is, the lateral direction indicated by the arrow Y, the nozzle 14 integral with the manifold also moves in the lateral direction.
Since the slide ring 32 is also driven laterally via 1 and slides laterally in the recess 35, no excessive load is applied to the nozzle 14 due to the thermal expansion. The expansion and contraction in the axial direction (the mold opening and closing direction indicated by arrow X) due to the thermal expansion of the nozzle 14 is absorbed by the sliding of the seal ring 31 and the slide ring 32 in the mold opening and closing direction. No excessive load is applied.

In this example, since the seal ring 31 and the slide ring 32 are formed of stainless steel having a lower thermal conductivity than the fixed mold plate 7 and the cavity block 10, the high-temperature nozzle 14 moves to the fixed mold plate 7. Of the fixed mold plate 7 can be prevented and the cycle time of injection molding can be shortened.

The present invention is not limited to the above example. For example, the structure for attaching the nozzle 14 to the manifold 11 and the materials and shapes of the seal ring 31 and the slide ring 32 may be other than those described above. Further, in the above example, the concave portion 35 into which the slide ring 32 is fitted is provided on the cavity block 10 side of the joint surface S between the fixed mold plate 7 and the cavity block 10, but instead, as shown by a chain line 38 in FIG. The concave portion may be provided on the fixed mold plate 7 side, or may be provided on both sides of the joint surface S between the fixed mold plate 7 and the cavity block 10.

Although a valve gate type hot runner mold has been described above, the present invention relates to a valve such as a valve which prevents resin leakage from the gate by precisely controlling the temperature of the gate without using a gate pin. The present invention can be applied to a hot runner mold having a gate seal mechanism other than the gate type.

[0019]

As explained above, according to the present invention,
Since the base of the nozzle is fixedly mounted on the manifold, resin leakage at the connection between the manifold and the nozzle can be reliably prevented.

A seal ring is fitted to the outer peripheral surface of the tip of the nozzle, and a slide ring having a hole for slidingly contacting the outer periphery of the seal ring is provided in a concave portion provided in the joint surface between the fixed mold plate and the cavity block. Since the slide ring is slidably fitted in the horizontal direction, even if the manifold thermally expands, the slide ring slides in the horizontal direction via the seal ring together with the nozzle, so that an excessive load is not applied to the nozzle portion.

In addition to the above effects, according to the second aspect of the invention, the heat conduction from the high-temperature nozzle to the fixed mold plate is suppressed, and the temperature of the fixed mold plate can be prevented from rising.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a hot runner mold showing an example of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a peripheral portion of a nozzle in FIG.

FIG. 3 is a longitudinal sectional view of a conventional hot runner mold.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hot runner metal mold, 2 ... Fixed mold, 7 ... Fixed side mold plate, 10 ... Cavity block, 11 ... Manifold,
14 nozzle, 14a base, 14b distal end outer peripheral surface,
18 gate, 31 seal ring, 32 slide ring, 33 hole, 35 recess.

Claims (2)

[Claims] 1. The bases of a plurality of nozzles penetrating a fixed side mold plate and having a front end opening facing a gate of a cavity block,
A fixed ring was attached to the manifold, a seal ring was fitted to the outer peripheral surface of the tip of the nozzle, and a slide ring provided with a hole that slidably contacted the outer periphery of the seal ring was provided at the joint surface between the fixed mold plate and the cavity block. A mold for a hot runner, which is slidably fitted in a recess in a lateral direction. 2. The hot runner mold according to claim 1, wherein at least one of the seal ring and the slide ring is formed of a material having a lower thermal conductivity than the fixed mold plate and the cavity block.