JP7699015B2 - Injection mold - Google Patents

Description

The present invention relates to an injection molding die.

Traditionally, injection molding has been widely used as a method for manufacturing synthetic resin molded products. A manifold is used as a means for filling the cavity of a mold with molten resin to efficiently manufacture molded products. The resin is maintained in a molten state from the sprue that connects the nozzle of the injection molding machine to the hot runner of the manifold, the resin passage of the runner bush, and the gate, and molten resin is filled into the cavity from the gate to manufacture synthetic resin molded products.

As for an injection mold used for injection molding, Patent Document 1 discloses an injection molding mold device for thermoplastic resin injection molding using a hot runner equipped with a valve gate mechanism that can fill a predetermined amount of molten resin into the cavity by opening and closing the gate, which is the entrance to the cavity of the valve gate device, with a needle pin (valve pin). The injection molding mold has a single nozzle with multiple gates installed in the cavity, and is configured such that with the base end of the nozzle body (runner bush) crimped onto the manifold, the resin passage of the nozzle body is connected and communicated with the hot runner of the manifold, and the molten resin is supplied into the cavity through the hot runner and the resin passage of the nozzle body.

As shown in Patent Document 2, the manifold arranged on the fixed plate of the injection molding die has flanges protruding from both sides, and is fixed to the fixed plate by screwing bolts through bolt insertion holes formed in the flanges into screw holes provided in the fixed plate.

JP 2007-83661 A WO2017/149723

However, the manifold is heated by the molten resin flowing through the hot runner formed inside it, causing thermal expansion. When the injection molding die is used repeatedly and the manifold expands and contracts repeatedly, the bolts screwed into the screw holes in the fixed plate become loose, causing the manifold to shift in its position on the fixed plate.

If the manifold is misaligned, a gap will form at the connection between the manifold and the runner bush, causing the problem that the molten resin flowing through the manifold's hot runner and the resin passages of the runner bush will leak through this gap.

Because the misalignment of the manifold installation position described above is slight, the molten resin leaks out little by little from the gap that appears at the connection between the manifold and the runner bush, and the resin that leaks out of the manifold and runner bush (leaked resin) cools, solidifies, and gradually accumulates.

This buildup of leaked resin occurs every time the injection mold is used, and the resin that has leaked and accumulated outside the manifold and runner bushings swells as additional resin leaks in, and is pushed away from the leaking area by the subsequently leaking resin.

Meanwhile, around the runner bushes and manifolds, there are numerous wires that supply electricity to heaters and other equipment that heat the molten resin flowing through the runner bushes and manifolds, and deposits of leaked resin can collide with these wiring and cut it off.

As mentioned above, the molten resin leaks little by little from the gap at the connection between the manifold and the runner bush, so it is difficult for the manager operating the injection molding machine to notice the resin leakage in the early stages. Often, the manager only notices it when the wiring is cut by the accumulation of leaked resin and the operation of the injection molding machine stops. When this happens, the accumulation of leaked resin spreads over a wide area on the fixed plate of the injection molding die, and the leaked resin fuses the parts of the injection molding die together, resulting in the problem that it takes a lot of time and money to restore the injection molding die.

In addition, to prevent heat from the manifold from being transferred to the fixed mold plate, an insulating ring may be installed between the opposing surfaces of the manifold and the fixed mold plate to surround the protruding end of the runner bushing that protrudes from the fixed mold plate.

However, because the insulating ring is arranged to prevent the heat of the manifold from being transferred to the fixed mold plate, a small gap is usually formed between the opposing surfaces of the insulating ring and the manifold, and even if the opposing surfaces of the insulating ring and the manifold are in contact with each other, the adhesion between the two is low, and the insulating ring cannot prevent the leakage of resin from the gap at the connection between the manifold and the runner bush and out to the outside, and therefore cannot solve the above-mentioned problems.

The present invention provides an injection molding die that can be applied to conventional injection molding dies, and that can detect leakage of molten resin from gaps that occur at the connection between the manifold and the runner bush at an early stage and immediately respond to the leakage of molten resin.

The injection mold of the present invention comprises:
a fixed mold plate having a runner bush having a resin passage for supplying molten resin to a cavity;
a manifold disposed on the fixed mold plate and provided with a hot runner communicating with a resin passage of the runner bush;
An injection molding die comprising an insulating ring disposed between the fixed die plate and the manifold,
The insulating ring is formed in a cylindrical shape surrounding the connection portion between the manifold and the runner bush when pressed against the manifold, and the insulating ring forms a leaked resin accommodating space portion for accommodating leaked resin leaked from the connection portion between the manifold and the runner bush by its opposing surfaces facing the manifold and the runner bush, and a sensing member for detecting the leaked resin is disposed within the leaked resin accommodating space portion.

In the above-mentioned injection molding die, the runner bush has a flange formed at the end protruding from the fixed mold plate and pressed against one end surface of the manifold, while the flange receiving surface of the runner bush is formed on the inner peripheral surface of the insulation ring, and the flange of the runner bush is pressed against the flange receiving surface of the insulation ring, and a leaking resin containing space is formed by the outer peripheral surface of the flange, the inner peripheral surface of the insulation ring facing the outer peripheral surface of the flange, and one end surface of the manifold exposed between the outer peripheral surface of the flange and the inner peripheral surface of the insulation ring and the flange receiving surface.

The injection molding die of the present invention has a cylindrical insulating ring surrounding the connection between the manifold and the runner bush, and the leaked resin leaking from the connection between the manifold and the runner bush is guided into the leaked resin storage space. A sensor member disposed in the leaked resin storage space immediately detects the occurrence of leaked resin, allowing the leaked resin to be dealt with reliably at an early stage, preventing unforeseen events such as the shutdown of the injection molding device.

In the above injection molding die, the runner bush has a flange formed at the end protruding from the fixed die plate and pressed against one end face of the manifold, while the flange receiving surface of the runner bush is formed on the inner peripheral surface of the insulating ring, and the flange of the runner bush is pressed against the flange receiving surface of the insulating ring. When a leaking resin storage space is formed by the outer peripheral surface of the flange, the inner peripheral surface of the insulating ring facing the outer peripheral surface of the flange, and one end face of the manifold exposed between the outer peripheral surface of the flange and the inner peripheral surface of the insulating ring and the flange receiving surface, the leaking resin leaking from the connection part between the manifold and the runner bush is reliably contained in the leaking resin storage space without leaking out to the outside, and even a small amount of leaking resin can be reliably detected by the detection member, making it possible to more reliably respond to leaking resin at an early stage.

Furthermore, the insulating ring allows the protruding end of the runner bush that protrudes from the fixed mold plate to be more reliably attached to the manifold, more effectively preventing leakage of molten resin from the connection between the manifold and the runner bush.

FIG. 1 is a cross-sectional view showing an injection molding die of the present invention. FIG. 2 is an enlarged view showing a main part of the injection molding die of FIG. 1. FIG. 4 is a cross-sectional view showing a heat insulating ring. FIG. 4 is a perspective view of the insulating ring of FIG. 3 . FIG. 2 is a diagram showing a hardware configuration of the leaked resin detection system. FIG. 2 is a cross-sectional view showing another example of the injection molding die of the present invention. FIG. 7 is an enlarged view showing a main part of the injection molding die of FIG. 6. FIG. 11 is a cross-sectional view showing another example of the heat insulating ring. FIG. 9 is a perspective view of the insulating ring of FIG. 8 .

An example of an injection molding die of the present invention will be described with reference to the drawings. As shown in Figs. 1 and 2, the injection molding die A comprises a fixed die plate 1, a runner bush 2 arranged on the fixed die plate 1, a manifold 3 arranged on the fixed die plate 1, and a heat insulating ring 4 interposed between the runner bush 2 and the manifold 3.

The fixed mold plate 1 has a movable mold plate (not shown) that pairs with the fixed mold plate 1, and a cavity (not shown) is formed by clamping the fixed mold plate 1 and the movable mold plate together. The fixed mold plate 1 has a runner bushing arrangement space 11 that communicates with the cavity and is used to arrange a runner bushing.

In the runner bushing arrangement space 11 of the fixed mold plate 1, the runner bushing 2 is arranged with its other end protruding from the fixed mold plate 1, and the other end protruding from the fixed mold plate 1 (protruding end) is formed with a circular flange 20 that protrudes outward.

The runner bush 2 has a resin passage 21 formed therethrough in the length direction, one end of which is formed with a gate portion 21a that communicates with the cavity, and the other end of the resin passage 21 is connected and communicates with a hot runner 31 of the manifold 3 described below. A valve pin 22 is disposed within the resin passage 21 of the runner bush 2, which moves along the length direction of the resin passage 21 to open and close the gate portion 21a. The valve pin 22 has its other end penetrated into the manifold 3 and connected to a drive unit 5 such as a hydraulic cylinder, air cylinder, or electric cylinder disposed on the manifold 3, and is configured to be movable along the length direction of the resin passage 21 by the drive unit 5.

The runner bush 2 is fitted with a band heater 23 on its outer periphery, and the molten resin that fills the cavity from the hot runner 31 of the manifold 3 through the resin passage 21 in the runner bush 2 is heated by the band heater 23 to maintain a good molten state.

A manifold 3 is disposed on the fixed mold plate 1. The manifold 3 has a hot runner 31 through which molten resin flows, and the other end opening of the hot runner 31 is connected to the nozzle (not shown) of the injection molding machine via a sprue, and is connected and communicated with the nozzle. On the other hand, the other end face 20b of the flange 20 of the runner bush 2 is pressed against the opening end face of one end opening of the hot runner 31, and the other end opening of the resin passage 21 of the runner bush 2 is connected and communicated watertight to the opening of one end of the hot runner 31. Under normal conditions, the molten resin flowing through the hot runner 31 and the resin passage 21 of the runner bush 2 does not leak from the connection part between the manifold 3 and the runner bush 2, that is, the connection interface between the other end face 20b of the flange 20 of the runner bush 2 and the one end face 32 of the manifold 3 that faces the other end face 20b of the flange 20.

The manifold 3 has flanges protruding from both sides, and is fixed onto the fixed plate 1 by screwing bolts through bolt insertion holes formed in the flanges into screw holes in the fixed plate.

As shown in Figures 1 and 2, an insulating ring 4 is disposed between the opposing surfaces of the runner bush 2 and the manifold 3. As shown in Figures 3 and 4, the insulating ring 4 is formed in a cylindrical (annular) shape, and a through hole 41 is formed in the center thereof, penetrating between both sides (between the upper and lower surfaces in Figure 1), through which the protruding end of the runner bush 2 can be inserted.

The other end face 4a of the insulation ring 4 is formed with a ring-shaped abutment portion 44 having a certain height so as to completely surround the through hole 41, and the abutment portion 44 is completely watertightly pressed against one end face 32 of the manifold 3, so that the leaked resin leaking from the connection portion between the manifold 3 and the runner bush 2 does not leak out of the insulation ring 4. It is also possible to configure the other end face 4a of the insulation ring 4 to be completely watertightly pressed against one end face 32 of the manifold without forming the abutment portion 44 on the other end face 4a of the insulation ring 4, so that the leaked resin leaking from the connection portion between the manifold 3 and the runner bush 2 does not leak out of the insulation ring 4.

Furthermore, an annular step is formed around the entire circumference of the inner circumferential surface of the insulating ring 4 in the center of its thickness direction (the vertical direction in FIG. 1), and this step forms a flange receiving surface 42 that receives one end surface 20a of the flange 20 of the runner bush 2.

The inner diameter of the through hole 41 of the insulating ring 4 on the fixed plate 1 side from the flange receiving surface 42 is approximately equal to the outer diameter of the portion of the protruding end of the runner bush 2 that does not form the flange 20, while the inner diameter of the manifold 3 side from the flange receiving surface 42 is slightly larger than the outer diameter of the flange 20 of the runner bush 2, and a space is formed between the outer peripheral surface 20c of the flange 20 of the runner bush 2 and the opposing inner peripheral surface 45 of the insulating ring 4, and this space is used as the leaked resin storage space B for receiving leaked resin that leaks from the connection between the manifold 3 and the runner bush 2.

A circular insert piece 43 protrudes from the entire circumference of one open end face of the through hole 41 of the insulation ring 4. With the insert piece 43 inserted into the gap formed between the inner peripheral surface of the other open end of the runner bush installation space 11 of the fixed mold plate 1 and the outer peripheral surface of the runner bush 2 facing this inner peripheral surface, one end face 4b of the insulation ring 4 is watertight pressed against the fixed mold plate 1 and the abutment portion 44 of the other end face 4a is watertight pressed against one end face 32 of the manifold 3. One end face 20a of the flange 20 of the runner bush 2 is watertight pressed against the flange receiving surface 42 of the insulation ring 4.

The leaked resin storage space B is formed by the outer peripheral surface 20c of the flange 20 of the runner bush 2, the inner surface (inner peripheral surface 45 and abutment portion 44) of the insulating ring 4 facing this outer peripheral surface, the flange receiving surface 42 exposed between the outer peripheral surface 20c of the flange 20 and the inner surface of the insulating ring 4, and one end surface 32 of the manifold 3, and the connection portion (connection interface) between the runner bush 2 and the manifold 3 is entirely exposed and positioned within the leaked resin storage space B.

In the insulating ring 4, a sensing member installation hole 46 that opens into the inner circumferential surface 45 forming the leaking resin storage space B is formed, and a sensing member C for detecting leaking resin is installed in the sensing member installation hole 46. There are no particular limitations on the sensing member C as long as it can detect leaking resin, and examples of the sensing member C include a pressure sensor that detects the pressure of the leaking resin and a temperature sensor that detects the temperature of the leaking resin, but a pressure sensor is preferred because it can stably detect leaking resin without being affected by the ambient temperature during injection molding.

The pressure sensor only needs to be able to detect the pressure of the leaking resin, and may detect the pressure of the leaking resin using either an electrical or mechanical mechanism, but a switch member that detects the pressure of the leaking resin using a mechanical mechanism is preferred, as it is less susceptible to the effects of heat from the molten resin.

A sensing member C is disposed in the sensing member disposing hole 46, and a sleeve member 61 is interposed between the sensing member C in the sensing member disposing hole 46 and the inner peripheral surface of the sensing member disposing hole 46 facing it in order to reduce as much as possible the transfer of heat from the molten resin flowing through the hot runner 31 of the manifold 3 to the sensing member C via the insulating ring and to prevent or reduce the occurrence of problems such as the sensing member C being overheated and breaking down.

Furthermore, a pin member 62 is disposed at the inner opening of the sensing member disposition hole 46 to prevent or reduce the occurrence of problems such as the leaked resin coming into direct contact with the sensing member C, causing the sensing member C to become overheated and break down. The pin member 62 is disposed within the sensing member disposition hole 46 so as to be movable inward and outward, and is configured to be displaced outward by the pressure of the leaked resin, smoothly transmitting the pressure of the leaked resin to the sensing member C.

The insulating ring 4 also has vent holes 48 that open into the leaking resin storage space B and into the outer peripheral surface 47 of the insulating ring 4, connecting and communicating the leaking resin storage space B with the outside of the insulating ring 4. These vent holes 48 are vent holes for discharging air pushed out by the leaking resin that has entered the leaking resin storage space B to the outside of the leaking resin storage space B.

The ventilation hole 48 formed in the insulating ring 4 is large enough to allow the air in the leaking resin storage space B to be discharged to the outside, while the leaking resin that has leaked into the leaking resin storage space B is cooled within the leaking resin storage space B and its viscosity increases, so it does not flow out to the outside through the ventilation hole 48.

The sensing member C may be provided with a wireless module 7. The wireless module 7 is a module for wireless data communication, and is a module for implementing normal wireless communication methods such as Wi-Fi (registered trademark), Bluetooth (registered trademark), W-CDMA standard, LTE standard, and LPWA (Low Power Wide Area) standard.

As shown in FIG. 5, a CPU (Central Processing Unit) 61 is electrically connected to the wireless module 7 attached to the sensing member C so that they can communicate with each other. Furthermore, the CPU 61 is electrically connected to a ROM (Read Only Memory) 62, a RAM (Random Access Memory) 63, an auxiliary storage device 64, and an output module 65 so that they can communicate with each other.

The CPU 61 is electrically connected to the detection member C via the A/D conversion unit 66 so as to be able to communicate with it. The A/D conversion unit 66 generates a digital signal that can be input to the CPU 61 by quantizing the analog signal output from the detection member C. The CPU 61 acquires the leaked resin signal transmitted from the detection member C in response to the detection of leaked resin as a digital signal. A general-purpose wireless module may be attached or installed to the CPU 61, the auxiliary storage device 64, the detection member C, and the output module 65, and electrically connected to be able to communicate with each other wirelessly.

Examples of the auxiliary storage device 64 include a solid state drive (SSD) and a hard disk drive (HDD). Examples of the output module 65 include a display, a speaker, and a mobile terminal device.

By loading a specific program onto the CPU 61 and RAM 63, the sensing member C and output module 65 are operated under the control of the CPU 61, and data is read and written to the RAM 63 and auxiliary storage device 64, thereby realizing the leaked resin detection system D.

The leaked resin detection system D is equipped with a leaked resin warning unit, which performs a predetermined function by executing a leaked resin warning program stored in the ROM 62 or the like under the control of the CPU 61.

Next, we will explain how to use the injection mold A. To perform injection molding using the injection mold A, the fixed mold plate 1 and the movable mold plate are clamped together to form a cavity between them, and then molten resin is supplied from the nozzle of the injection molding machine through the sprue to the hot runner 31 of the manifold 3. While operating the valve pin 22, molten resin is supplied into the cavity through the resin passage 21 and gate portion 21a of the runner bush 2, which is connected and communicated with the hot runner 31, to form an injection molded product of the desired shape.

During injection molding, resin that has been heated to a high temperature and is in a molten state flows through the hot runners 31 of the manifold 3, causing the manifold 3 to be heated by the molten resin and expand. On the other hand, when injection molding is not being performed, no molten resin flows through the hot runners 31 of the manifold 3, so the manifold 3 is in a cooled state and does not expand as described above.

In addition, during injection molding, vibrations occur due to the drive of the injection molding machine, the clamping and opening of the fixed mold plate 1 and the movable mold plate, and the drive device that drives the valve pin 22.

In this way, various factors that arise during injection molding can cause the bolts that secure the manifold 3 to the fixed mold plate 1 to become loose, causing the manifold 3 to become loosely fixed to the fixed mold plate 1.

When this happens, the relative positions of the manifold 3 and the runner bush 2 change, and the adhesion between the other end face 20b of the flange 20 of the runner bush 2 and the opposing one end opening end face 32a of the hot runner 31 decreases, causing the molten resin to leak from the connection between the runner bush 2 and the manifold 3.

The adhesion between the contact portion 44 of the insulation ring 4 and the opposing one end face 32 of the manifold 3 also decreases, but under normal conditions, the adhesion between the contact portion 44 of the insulation ring 4 and the opposing one end face 32 of the manifold 3 is higher than the adhesion between the other end face 20b of the flange portion 20 of the runner bush 2 and the opposing one end opening end face 32a of the hot runner 31, and the leaked resin preferentially enters and is accommodated in the leaked resin accommodation space B, which can enter with lower resistance than the interface between the insulation ring 4 and the one end face 32 of the manifold 3, so the leaked resin does not leak out of the insulation ring 4.

In the initial stage, leakage of molten resin from the connection between the runner bush 2 and the manifold 3 does not occur in large quantities all at once, but occurs gradually in small amounts. That is, the leaked resin generated during the previous injection molding flows into the leaked resin storage space B and is stored thereafter, after which it is cooled and becomes a deposit. Similarly, leaked resin is generated during the injection molding performed after this injection molding, and flows into the leaked resin storage space B and is stored therein. Since the runner bush 2 and the manifold 3 are heated during injection molding, the leaked resin already stored in the leaked resin storage space B is also heated and softened, and the leaked resin generated by multiple leaks is integrated and deforms to fit the shape of the leaked resin storage space B as necessary, and is deposited in the leaked resin storage space B. Then, when the accumulation of the leaked resin in the leaked resin storage space B progresses to a certain extent, the leaked resin deposit enters the sensing member placement hole 46 that opens into the leaked resin storage space B, and the sensing member C placed in this sensing member placement hole 46 detects the leaked resin.

The leaked resin storage space B is formed as an annular space that is a continuous space that surrounds the entire circumference of the flange 20 of the runner bush 2, and all of the connection parts between the runner bush 2 and the manifold 3 are contained in an exposed state within the leaked resin storage space B, so that all of the leaked resin that leaks from the connection parts between the runner bush 2 and the manifold 3 is smoothly contained within the leaked resin storage space B and is reliably detected by the detection member C.

When the sensing member C detects leaking resin, it transmits a leaking resin signal to the CPU 61. The CPU 61 receives this leaking resin signal and outputs a warning signal indicating that resin is leaking to the output module 65, which then outputs a warning signal such as a warning sound or a warning display from the output module 65.

Then, the manager of the injection molding equipment who receives the warning signal can stop the operation of the injection molding equipment and easily check for resin leakage and repair the leakage area at an early stage, preventing damage to the injection molding equipment caused by leaked resin and allowing injection molding to be resumed early.

In the above-mentioned injection molding die A, one end face 20a of the flange 20 of the runner bush 2 is received by the flange receiving surface 42 of the insulating ring 4, and the flange 20 of the runner bush is pressed toward the manifold 3 by this flange receiving surface 42, and the other end face 20b of the flange 20 of the runner bush is crimped in a watertight state to one end opening end face 32a of the hot runner 31 in the manifold 3. However, as shown in Figures 6 to 9, The injection molding die A' may be one in which the other end surface 20b of the flange 20 of the runner bush 2 is watertightly press-fitted to one end surface 32 (one end opening end surface 32a of the hot runner 31) of the manifold 3 by providing a connecting portion 24 protruding from the protruding end, specifically, the other end surface 20b of the flange 20, and watertightly screwing a screw portion 24a formed on the outer peripheral surface of this connecting portion 24 into a connecting recess 33 formed in one end opening of the hot runner 31 of the manifold 3. The resin passage 21 of the runner bush 2 passes through the connecting portion 24 and is connected and communicates with the hot runner 31 of the manifold 3.

Even in an injection molding device configured in this manner, the bolts that secure the manifold 3 to the fixed mold plate 1 may become loose due to the expansion of the manifold 3 and the vibrations that occur when the injection molding device is operated as described above, causing the manifold 3 to become loosened relative to the fixed mold plate 1.

When this happens, the relative positions of the manifold 3 and the runner bush 2 change, loosening occurs in the screwed state between the connection part 24 of the runner bush 2 and the connection recess 33 of the manifold 3, the adhesion between the other end surface 20b of the flange part 20 of the runner bush 2 and the opposing one end surface 32 of the manifold 3 decreases, and the molten resin leaks from the connection part between the runner bush 2 and the manifold 3.

In the injection molding die A', an insulating ring 4' is also interposed between the opposing surfaces of the manifold 3 and the fixed die plate 1. The insulating ring 4' has the same structure as the insulating ring 4 described above, except that the insert piece 43 and the abutment portion 44 are not formed, so the same reference numerals are used and the description is omitted.

In the insulating ring 4', as in the insulating ring 4, a space is formed between the outer peripheral surface 20c of the flange 20 of the runner bush 2 and the opposing inner peripheral surface 45 of the insulating ring 4, and this space is used as the leaked resin storage space B for receiving the leaked resin leaked from the connection between the manifold 3 and the runner bush 2. The connection portion (connection interface) between the runner bush 2 and the manifold 3, i.e., the connection portion between the other end surface 20b of the flange 20 of the runner bush 2 and the opposing one end surface 32 of the manifold 3, is fully exposed and positioned within the leaked resin storage space B.

Even in an injection molding die A' using a heat insulating ring 4', if molten resin leaks from the connection (connection interface) between the runner bush 2 and the manifold 3, the leaked resin will enter and be contained in the leaked resin storage space B, forming a deposit of leaked resin. This deposit of leaked resin will be detected by the sensor C disposed in the leaked resin storage space B, and the manager of the injection molding device A' will be notified of the occurrence of the leakage of molten resin in the same manner as described above.

In the above description, the injection molding die A' uses an insulating ring 4' that does not have an insert piece 43 or an abutment portion 44, but an insulating ring that has either or both of an insert piece 43 and an abutment portion 44 may also be used.

1 Fixed mold plate 2 Runner bush 3 Manifold
31 Hot runner 4 Insulation ring
4a Other end face of the insulation ring
4b One end surface of the heat insulating ring 5 Drive unit
20 Runner bush flange
20a One end face of flange
20b Other end surface of flange
21 Resin passage
21b: the other end opening face of the resin passage
22 Valve pin
41 Through hole
42 Flange receiving surface
43 Insert
44 Contact part
45 Inner surface
46 Sensing member installation hole
48 Vent A Injection mold B Leaked resin storage space C Sensor

Claims (1)

a fixed mold plate having a runner bush having a resin passage for supplying molten resin to a cavity;
a manifold disposed on the fixed mold plate and provided with a hot runner communicating with a resin passage of the runner bush;
An injection molding die comprising an insulating ring disposed between the fixed die plate and the manifold,
the insulating ring is formed in a cylindrical shape surrounding the connection portion between the manifold and the runner bush when it is pressed against the manifold, and the insulating ring forms a leaked resin accommodating space portion for accommodating leaked resin leaked from the connection portion between the manifold and the runner bush by a surface facing the manifold and the runner bush, and a sensing member for sensing the leaked resin is disposed in the leaked resin accommodating space portion ,
the runner bush has a flange formed at an end portion protruding from the fixed mold plate and pressed against one end surface of the manifold, while a flange receiving surface of the runner bush is formed on an inner peripheral surface of the insulation ring and the flange of the runner bush is pressed against the flange receiving surface of the insulation ring, and the leaked resin accommodation space is formed by the flange outer peripheral surface, the inner peripheral surface of the insulation ring facing the flange outer peripheral surface, and one end surface of the manifold exposed between the flange outer peripheral surface and the inner peripheral surface of the insulation ring and the flange receiving surface .

Images