JPH1128743A - Mold for hot runner injecting molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for hot runner injection molding which enables efficient heating of a connecting part (large-bore part) of a hot nozzle with a manifold. SOLUTION: This mold for injection molding is so designed that molten resin is filled in a cavity 16 from a runner 18 of a manifold 12 through a hot nozzle 15, and a groove 20 for holding a sheath heater 22 is so formed as to be along the runner 18. In the part of the groove 20 being opposite to the hot nozzle 15, a high heat conductivity material (copper material 25) is so inserted as to come into contact with the sheath heater 22, and the lower side of the copper material 25 is in contact with the large-bore part 15a of the hot nozzle 15. Part of the heat of the sheath heater 22 is conducted efficiently to the large- bore part 15a of the hot nozzle 15 through the copper material 25 and thereby sufficient heating can be obtained. As the result, an excellent molten state of plastic can be maintained in the hot nozzle 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot runner type injection mold, and more particularly to a technique for heating a manifold and a hot nozzle.

[0002]

2. Description of the Related Art In order to improve molding efficiency, a hot runner injection molding die used for injection molding of a thermoplastic resin usually keeps plastic from a sprue or a runner to a vicinity of a gate in a molten state. In the hot runner injection mold, a plurality of runners are formed in a manifold containing a heater. As the manifold, for example, there is a manifold in which a runner is bored in an integral member.

More specifically, as shown in FIG. 4, a plurality of (only one is shown in FIG. 4) runners 18 are respectively provided on the lower surface of the manifold 12 (FIG. 4).
(Only one is shown) is fixed, and this hot nozzle 15 is heated by an appropriate heating means (for example, a band heater 15b). The connecting portion of the hot nozzle 15 with the manifold 12 is a large diameter portion 15a, and this large diameter portion 15a is also a portion supported by a mold (fixed mold 1). The molten resin injected into the runner 18 of the manifold 12 by an injection molding machine (not shown) is supplied to the hot nozzle 15 and its gate 1.
4 and into the cavity 16.

Here, as means for heating the manifold 12, grooves 19 and 20 are formed on the upper and lower surfaces of the manifold 12, for example, along the runners 18, respectively. Accommodates the sheath heaters 21 and 22, respectively, and further includes the grooves 19 and
20 is filled with thermocements 23 and 24 as heat insulating materials, respectively.

[0005]

As described above, although the hot nozzle 15 is heated by, for example, the band heater 15b, the heat of the hot nozzle 15 is reduced by contact with the mold (fixed mold 1). Heat is easily radiated from the diameter portion 15a) to the mold, and the heating of the hot nozzle 15 is not sufficient. In particular, the temperature of the contact portion (large diameter portion 15a) of the hot nozzle 15 with the manifold 12 tends to be lower than other portions, and in this case, it becomes difficult to maintain a good molten state of the plastic. There has been a strong demand for effectively heating the large diameter portion 15a. Since the large-diameter portion 15a is usually a thin portion, it was not possible to secure a portion where the heater is to be mounted.

The present invention has been made in view of the above-mentioned problems of the related art, and it is possible to efficiently conduct heat from a sheath heater provided in a manifold to a large-diameter portion of a hot nozzle for heating. It is an object of the present invention to provide a hot runner injection mold that can be used.

[0007]

In order to achieve the above object, the present invention provides a method in which a cavity is filled with a molten resin through a hot nozzle from a runner of a manifold, and at least a lower surface of the manifold is provided. To
In the hot runner injection molding die in which a groove for accommodating a heater is formed, a high heat conductive material that is in contact with the heater is inserted into a portion of the groove that faces the hot nozzle. The high thermal conductive material is in contact with the upper surface of the hot nozzle.

According to the operation of the present invention, the heat of the heater accommodated in the groove on the lower surface of the manifold is efficiently conducted to the large-diameter portion of the hot nozzle through the high-heat conductive material, and the large-diameter portion is transmitted to the large-diameter portion. It can be heated sufficiently. Therefore, the molten state of the plastic can be favorably maintained in the hot nozzle.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of one embodiment of a hot runner injection mold according to the present invention, FIG. 2 is a schematic view of the manifold shown in FIG. 1 from below, and FIG.
FIG. 3 is an enlarged view of the vicinity of the manifold and the hot nozzle shown in FIG.

First, as shown in FIG. 1, with respect to an example of the overall configuration of a hot runner injection mold according to this embodiment, reference numeral 1 denotes a fixed mold, 3 denotes a movable mold, and these fixed mold 1 and movable mold 3 Are movable in the vertical direction in the figure to open and close, and a plurality of product-shaped cavities 16 are formed inside the fixed mold 1 and the movable nest (core) 4 of the movable mold 3 at the time of mold clamping. . A manifold spacer block 2 is fixed on the upper surface of the fixed mold 1. An injection molding machine (not shown) is provided on the upper surface of the manifold spacer block 2.
Is fixed to a fixed side platen (not shown). A manifold 12 containing sheath heaters 21 and 22 is provided between the fixed die 1 and the fixed-side mounting plate 7. This manifold 12
Is provided with a sprue bush 10 to which a nozzle of the injection molding machine (not shown) is connected. Note that reference numeral 9
Indicates a locate ring provided on the fixed-side mounting plate 7.

As shown in FIGS. 1 to 3, a sprue 17 communicating with the sprue bush 10 is formed in the manifold 12, and a runner 18 branched from the sprue 17 is formed. The final branch of the runner 18 is open at the lower end of the manifold 12. At four corners on the lower surface of the manifold 12, hot nozzles 15 communicating with the respective runners 18 are fixed. At the lower end of this hot nozzle 15,
It has a gate 14 that opens to a cavity 16. Reference numeral 1a in FIG. 3 indicates a cooling water passage for cooling the fixed mold 1.

On the other hand, as shown in FIG. 1, the movable mold 3 has a movable nest 4 forming the inside of a product, and a receiving plate 5 is attached to the rear surface (the lower surface in the figure) of the movable mold 3. On the lower surface of the plate 5, a movable mounting plate 8 mounted on a movable platen of an injection molding machine (not shown) is mounted via a spacer block 6. A protruding plate 11 is provided between the movable-side mounting plate 8 and the receiving plate 5 and moves up and down relative to the drawing, and a protruding pin 13 protrudes from the protruding plate 11. The protruding pins 13 are slidably penetrated through the receiving plate 5 and the movable nest 4, and the ends thereof are located facing the cavity 16.

At the time of molding, with the mold closed,
The molten resin is injected from the nozzle of the injection molding machine. The resin flows from the sprue 17 through the runner 18 and the hot nozzle 15 into the cavity 16 through the gate 14. After the resin filled in the cavity 16 is solidified, the mold is opened, and the product, which is the resin solidified in the cavity 16, is taken out. At this time, the ejection pin 13 projects the product and releases the product.

Next, features of the present embodiment will be described. As shown in FIGS. 2 and 3, grooves 19 and 20 are formed on the upper surface and the lower surface of the manifold 12, for example, along the runner 18. Each is housed. Although the shape of the grooves 19 and 20 is not limited to the above, it is essential that a part of the groove 20 on the lower surface of the manifold 12 pass above the hot nozzle 15. Each groove 1
9 and 20 include thermocements 23 and 2 as heat insulating materials.
4 (specifically, for example, Thermocement T-63). Thereby, sheath heater 2
The heat of 1 and 22 is hardly dissipated outside the manifold 12.
Each hot nozzle 15 in the groove 20 on the lower surface of the manifold 12
The copper material 25 as a high heat conductive material is provided at a portion (the portion where the groove 20 in FIG. 2 is solidly painted) opposed to the large diameter portion 15b.
Are fitted respectively. Although aluminum may be used instead of the copper material 25, a high melting point substance is preferable.

The process until the copper material 25 is fitted will be described in detail. The paste 20 is filled with the thermo-cement 24 in the groove 20 on the lower surface of the manifold 12.
The filling amount of 4 is set to be smaller at the place where the copper material 25 is fitted than at other places. Thereafter, a predetermined portion of the groove 20 (a portion facing the large diameter portion 15b of each hot nozzle 15)
Copper materials 25 are respectively driven into the heater, and are brought into contact with the sheath heater 22. Here, the copper material 25 is held in frictional contact with the wall surface of the groove 20, and the thermocement 24 is
5 functions as an adhesive for bonding to the sheath heater 22. If necessary, the copper material 25 is cut or polished so that the lower surface thereof is flush with the lower surface of the manifold 12.

In the present embodiment, part of the heat of the sheath heater 22 housed in the groove 20 on the lower surface of the manifold 12 is efficiently transmitted to the large-diameter portion 15a of the hot nozzle 15 through the copper material 25. Thus, the large diameter portion 15a can be sufficiently heated. Therefore, the molten state of the plastic can be favorably maintained in the hot nozzle 15. In addition, since the hot nozzle 15 is heated using a part of the heat of the sheath heater 22 of the manifold 12,
Running cost does not increase.

[0017]

Since the present invention is constructed as described above, a part of the heat of the heater accommodated in the groove on the lower surface of the manifold is efficiently transmitted to the hot nozzle through the high thermal conductive material. Conduction is conducted to the large diameter portion, and the large diameter portion can be sufficiently heated. Therefore, in the hot nozzle,
The molten state of the plastic can be kept good. Since the hot nozzle is heated using a part of the heat of the manifold heater, the running cost is not increased.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of a hot runner injection mold according to the present invention.

FIG. 2 is a schematic view of the manifold shown in FIG. 1 from below.

FIG. 3 is an enlarged view of the vicinity of a manifold and a hot nozzle shown in FIG. 1;

FIG. 4 is an enlarged view of the vicinity of a manifold and a hot nozzle of a conventional hot runner injection mold.

[Explanation of symbols]

 Reference Signs List 1 fixed type 1a cooling water passage 2 manifold spacer block 3 movable type 4 movable insert (core) 5 receiving plate 6 spacer block 7 fixed side mounting plate 8 movable side mounting plate 9 locate ring 10 sprue bush 11 protruding plate 12 manifold 13 Projection pin 14 Gate 15 Hot nozzle 15a Large diameter portion (flange portion) 15b Band heater 16 Cavity 17 Sprue 18 Runner 19,20 Groove 21,22 Sheath heater 23,24 Thermocement 25 Copper (high heat conductive material)

Claims (1)

[Claims] 1. A hot runner in which a cavity is filled with a molten resin from a runner of a manifold via a hot nozzle, and a groove for accommodating a heater is formed on at least a lower surface of the manifold. In the injection molding die, a high heat conductive material that is in contact with the heater is inserted into a portion of the groove that faces the hot nozzle,
The hot runner injection molding die, wherein the high thermal conductive material is in contact with the upper surface of the hot nozzle.