Mold for injection molding

Abstract

To provide a die for injection molding, which is capable of detecting leakage of a molten resin from a gap formed in a joint between a manifold and a runner bush at an early stage and immediately responding to the leakage of the molten resin.SOLUTION: A die for injection molding comprises: a fixed plate on which a runner bush is arranged; a manifold provided with a hot runner disposed on the fixed plate and communicating with a resin passage of the runner bush; and a heat insulation ring. The heat insulation ring is formed in a cylindrical shape that surrounds a joint between the manifold and the runner bush while being crimped to the manifold; a leaked resin accommodating space for accommodating a leaked resin leaked from the joint between the manifold and the runner bush is formed by a facing surface of the manifold and the runner bush; and a sensing member for sensing the leaked resin is disposed in the leaked resin accommodating space.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an injection mold.

Background Art

[0002] Conventionally, injection molding has been widely used as a method for manufacturing synthetic resin molded products. A manifold is used as a means for efficiently manufacturing a molded product by filling a cavity of a mold with molten resin. The resin is maintained in a molten state from a sprue connected to a nozzle of an injection molding machine to a hot runner of the manifold, a resin passage of a runner bushing, and a gate, and the molten resin is filled into the cavity from the gate to manufacture a synthetic resin molded product.

[0003] As an injection mold for injection molding, Patent Document 1 discloses an injection mold for a thermoplastic resin using a hot runner having a valve gate mechanism capable of filling a predetermined amount of molten resin into a cavity by opening and closing a gate, which is an inlet to the cavity of a valve gate device, with a needle pin (valve pin). A single nozzle having a plurality of gates is installed in the cavity. The resin passage of the nozzle body is connected and communicated with the hot runner of the manifold in a state where the base end portion of the nozzle body (runner bushing) is pressure-bonded to the manifold, and the molten resin is configured to be supplied into the cavity through the hot runner and the resin passage of the nozzle body.

[0004] Also, as shown in Patent Document 2, a manifold disposed on a fixed mold plate of an injection mold has flange portions protruding from both side surfaces thereof, and is fixed on the fixed mold plate by screwing bolts through bolt insertion holes formed in the flange portions into screw holes provided in the fixed mold plate.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, since the manifold is heated by the molten resin flowing through the hot runner formed inside thereof and undergoes thermal expansion, when the injection mold is repeatedly used and the expansion and contraction of the manifold are repeated, the bolts screwed into the screw holes of the stationary platen become loose, and the arrangement position of the manifold on the stationary platen is displaced.

[0007] When the arrangement position of the manifold is displaced, a gap is formed at the connection portion between the manifold and the runner bushing, and through this gap, there arises a problem that the molten resin flowing through the resin passages of the hot runner of the manifold and the runner bushing leaks out.

[0008] Since the displacement of the arrangement position of the above-mentioned manifold is slight, the leakage of the molten resin from the gap formed at the connection portion between the manifold and the runner bushing occurs little by little, and the resin leaked outside the manifold and the runner bushing (leaked resin) cools and solidifies and gradually accumulates.

[0009] This accumulation of the leaked resin occurs with each use of the injection mold, and the resin leaked outside the manifold and the runner bushing and deposited grows larger as subsequent leaked resin is added, and is pushed in a direction away from the leakage portion by the subsequent leaked resin.

[0010] On the other hand, around the runner bushing and the manifold, numerous wirings for supplying electricity to heaters and other devices for heating the molten resin flowing through the runner bushing and the manifold are arranged, and there occurs a situation where the deposited matter of the leaked resin collides with the wiring and cuts the wiring.

[0011] As described above, since the leakage of the molten resin from the gap generated at the connection portion between the manifold and the runner bush occurs little by little, it is difficult for the administrator operating the injection molding apparatus to notice it at the initial stage of the resin leakage. Often, it is not until the wiring is cut by the deposit of the leaked resin and the operation of the injection molding apparatus stops that the problem is noticed. When such a state is reached, the deposit of the leaked resin spreads over a wide range on the fixed mold plate of the injection mold, and the parts of the injection mold are fused and integrated by the leaked resin, resulting in the problem that a great deal of cost and time are required for the recovery of the injection mold.

[0012] Further, in order to prevent the heat of the manifold from being transmitted to the fixed mold plate side, a heat insulating ring may be attached between the opposing surfaces of the manifold and the fixed mold plate so as to surround the protruding end portion of the runner bush protruding from the fixed mold plate.

[0013] However, since the heat insulating ring is disposed to prevent the heat of the manifold from being transmitted to the fixed mold plate side, a slight gap is usually formed between the opposing surfaces of the heat insulating ring and the manifold. Also, even when the opposing surfaces of the heat insulating ring and the manifold are in contact with each other, the adhesion between the two is low, and the heat insulating ring cannot prevent the leaked resin from flowing out to the outside from the gap generated at the connection portion between the manifold and the runner bush, and thus cannot solve the above-described problem.

[0014] The present invention can be applied to a conventional injection mold, and provides an injection mold that can detect the leakage of the molten resin from the gap generated at the connection portion between the manifold and the runner bush at an initial stage and can immediately respond to the leakage of the molten resin.

Means for Solving the Problem

[0015] The injection mold of the present invention includes a fixed mold plate provided with a runner bush having a resin passage for supplying the molten resin to the cavity, A manifold provided on the fixed mold plate and communicating with the resin passage of the runner bush, An injection mold including a heat insulation ring disposed between the opposing surfaces of the fixed mold plate and the manifold, The heat insulation ring is formed in a cylindrical shape that surrounds the connection portion between the manifold and the runner bush while being crimped to the manifold, and the heat insulation ring forms a leakage resin accommodation space portion that accommodates the leakage resin leaked from the connection portion between the manifold and the runner bush by the opposing surfaces of the manifold and the runner bush, and a sensing member for sensing the leakage resin is disposed in the leakage resin accommodation space portion.

[0016] In the injection mold, the runner bush has a flange portion formed at the protruding end portion from the fixed mold plate and crimped to one end surface of the manifold, while a flange portion receiving surface of the runner bush is formed on the inner peripheral surface of the heat insulation ring, and the flange portion of the runner bush is crimped to the flange portion receiving surface of the heat insulation ring, and a leakage resin accommodation space portion is formed by the outer peripheral surface of the flange portion, the inner peripheral surface of the heat insulation ring facing the outer peripheral surface of the flange portion, and one end surface of the manifold and the flange portion receiving surface exposed between the outer peripheral surface of the flange portion and the inner peripheral surface of the heat insulation ring.

Effect of the Invention

[0017] The injection mold of the present invention surrounds the connection portion between the manifold and the runner bush with a cylindrical heat insulation ring, guides the leakage resin leaked from the connection portion between the manifold and the runner bush into the leakage resin accommodation space portion, and immediately senses the occurrence of the leakage resin by the sensing member disposed in the leakage resin accommodation space portion, and can surely respond to the leakage resin at an initial stage, and can prevent an unexpected situation such as the stop of the injection molding apparatus.

[0018] In the above injection molding die, the runner bush has a flange portion formed at the protruding end from the fixed mold plate and crimped to one end surface of the manifold. On the other hand, a flange receiving surface of the runner bush is formed on the inner peripheral surface of the heat insulating ring, and the flange portion of the runner bush is crimped to the flange receiving surface of the heat insulating ring. When a leakage resin accommodation space portion is formed by the outer peripheral surface of the flange portion, the inner peripheral surface of the heat insulating ring facing the outer peripheral surface of the flange portion, and one end surface and the flange receiving surface of the manifold exposed between the outer peripheral surface of the flange portion and the inner peripheral surface of the heat insulating ring, the leakage resin leaking from the connection portion between the manifold and the runner bush can be surely accommodated in the leakage resin accommodation space portion without leaking to the outside, and even a small amount of leakage resin can be surely detected by the detection member, and the response at the initial stage to the leakage resin can be more surely performed.

[0019] Furthermore, by the heat insulating ring, the protruding end portion of the runner bush protruding from the fixed mold plate can be surely adhered to the manifold, and the leakage of the molten resin from the connection portion between the manifold and the runner bush can be more effectively prevented.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0021] An example of the injection mold of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the injection mold A includes a fixed mold plate 1, a runner bush 2 disposed on the fixed mold plate 1, a manifold 3 disposed on the fixed mold plate 1, and a heat insulating ring 4 interposed between the runner bush 2 and the manifold 3.

[0022] The fixed mold plate 1 has a moving mold plate (not shown) that mates with the fixed mold plate 1. By clamping the fixed mold plate 1 and the moving mold plate, a cavity (not shown) is formed, and the fixed mold plate 1 has a runner bush arrangement space portion 11 for communicating with the cavity and disposing the runner bush.

[0023] In the runner bush arrangement space portion 11 of the fixed mold plate 1, the runner bush 2 is disposed with its other end protruding from the fixed mold plate 1. An annular flange portion 20 protruding outward is formed at the other end (protruding end portion) protruding from the fixed mold plate 1.

[0024] A resin passage 21 penetrating in the length direction is formed in the runner bush 2. At one end of the resin passage 21, a gate portion 21a communicating with the cavity is formed, and the other end of the resin passage 21 is connected and communicated with a hot runner 31 of the manifold 3 described later. And in the resin passage 21 of the runner bush 2, a valve pin 22 for moving along the length direction of the resin passage 21 to open and close the gate portion 21a is disposed. The valve pin 22 has its other end penetrating through the manifold 3 and is connected to a driving device 5 such as a hydraulic cylinder, an air cylinder, or an electric cylinder disposed on the manifold 3, and is configured to be movable along the length direction of the resin passage 21 by the driving device 5.

[0025] Note that a band heater 23 is mounted on the outer peripheral surface of the runner bush 2, and the molten resin filled into the cavity through the resin passage 21 in the runner bush 2 from the hot runner 31 of the manifold 3 is heated by the band heater 23 to maintain a good molten state.

[0026] The manifold 3 is disposed on the fixed mold plate 1. The manifold 3 has a hot runner 31 through which molten resin flows inside. The nozzle (not shown) of an injection molding machine is connected to the other end opening of the hot runner 31 via a sprue and is connected and communicated. On the other hand, the other end face 20b of the flange portion 20 of the runner bush 2 is pressure-bonded to the opening end face of one end of the hot runner 31. The other end opening of the resin passage 21 of the runner bush 2 is watertightly connected and communicated with the opening of one end of the hot runner 31. In a normal state, the molten resin flowing through the resin passages 21 of the hot runner 31 and the runner bush 2 is configured not to leak from the connection portion between the manifold 3 and the runner bush 2, that is, the connection interface between the other end face 20b of the flange portion 20 of the runner bush 2 and one end face 32 of the manifold 3 facing the other end face 20b of this flange portion 20.

[0027] Note that the manifold 3 has flange portions protruding from both of its side surfaces, and is fixed on the fixed mold plate 1 by screwing bolts through bolt insertion holes formed in the flange portions into screw holes provided in the fixed mold plate.

[0028] As shown in FIGS. 1 and 2, a heat insulating ring 4 is disposed between the opposing surfaces of the runner bush 2 and the manifold 3. As shown in FIGS. 3 and 4, the heat insulating ring 4 is formed in a cylindrical (annular) shape, and a through hole 41 through which the protruding end portion of the runner bush 2 can be inserted is formed to penetrate between both surfaces (upper and lower surfaces in FIG. 1).

[0029] On the other end face 4a of the heat insulation ring 4, an annular contact portion 44 having a constant height is formed so as to entirely surround the through hole 41. The contact portion 44 is entirely and watertightly pressure-bonded to one end face 32 of the manifold 3, and is configured such that the leaked resin leaking from the connection portion between the manifold 3 and the runner bush 2 does not leak outside the heat insulation ring 4. Note that, without forming the contact portion 44 on the other end face 4a of the heat insulation ring 4, the other end face 4a of the heat insulation ring 4 may be entirely and watertightly pressure-bonded to one end face 32 of the manifold so that the leaked resin leaking from the connection portion between the manifold 3 and the runner bush 2 does not leak outside the heat insulation ring 4.

[0030] Furthermore, on the inner peripheral surface of the heat insulation ring 4, an annular stepped portion is formed over the entire circumference at the central portion in the thickness direction (vertical direction in FIG. 1), and this stepped portion is formed on a flange portion receiving surface 42 that receives one end face 20a of the flange portion 20 of the runner bush 2.

[0031] In the through hole 41 of the heat insulation ring 4, the inner diameter of the portion on the fixed mold plate 1 side from the flange portion receiving surface 42 substantially matches the outer diameter of the portion where the flange portion 20 is not formed at the protruding end portion of the runner bush 2. On the other hand, the inner diameter of the portion on the manifold 3 side from the flange portion receiving surface 42 is formed to be slightly larger than the outer diameter of the flange portion 20 of the runner bush 2. A space portion is formed between the outer peripheral surface 20c of the flange portion 20 of the runner bush 2 and the inner peripheral surface 45 of the heat insulation ring 4 facing this, and this space portion is used as a leaked resin accommodation space portion B for receiving the leaked resin leaking from the connection portion between the manifold 3 and the runner bush 2.

[0032] An annular insertion piece 43 projects over the entire circumference at one end opening end face of the through hole 41 of the heat insulating ring 4. The heat insulating ring 4 is inserted into a gap formed between the inner peripheral surface of the other end opening of the runner bush arrangement space 11 of the fixed mold plate 1 and the outer peripheral surface of the runner bush 2 facing this inner peripheral surface. In this inserted state, one end face 4b is watertightly crimped to the fixed mold plate 1, and the contact portion 44 of the other end face 4a is watertightly crimped to one end face 32 of the manifold 3. And, one end face 20a of the flange portion 20 of the runner bush 2 is watertightly crimped to the flange portion receiving surface 42 of the heat insulating ring 4.

[0033] The resin leakage accommodation space B is formed by the outer peripheral surface 20c of the flange portion 20 of the runner bush 2, the inner surface (inner peripheral surface 45 and contact portion 44) of the heat insulating ring 4 facing this outer peripheral surface, the flange portion receiving surface 42 exposed from between the outer peripheral surface 20c of the flange portion 20 and the inner surface of the heat insulating ring 4, and one end face 32 of the manifold 3. The connection portion (connection interface) between the runner bush 2 and the manifold 3 is entirely exposed and positioned within the resin leakage accommodation space B.

[0034] And, in the heat insulating ring 4, a sensing member arrangement hole 46 opening to the inner peripheral surface 45 forming the resin leakage accommodation space B is formed in the inner peripheral surface 45, and a sensing member C for sensing the leaked resin is arranged in the sensing member arrangement hole 46. The sensing member C is not particularly limited as long as it can sense the leaked resin. For example, a pressure sensor for detecting the pressure of the leaked resin, a temperature sensor for detecting the temperature of the leaked resin, etc. can be mentioned. However, since it can stably detect the leaked resin without being affected by the ambient temperature during injection molding, a pressure sensor is preferred.

[0035] The pressure sensor only needs to be able to detect the pressure of the leaked resin, and it may detect the pressure of the leaked resin by either an electrical or mechanical mechanism. However, since it is not easily affected by the heat of the molten resin, a switch member that detects the pressure of the leaked resin by a mechanical mechanism is preferred.

[0036] The sensing member C is disposed in the sensing member installation hole 46. However, in order to reduce as much as possible the heat of the molten resin flowing through the hot runner 31 of the manifold 3 from being transmitted to the sensing member C via the heat insulating ring and to prevent or reduce problems such as the sensing member C being overheated and malfunctioning, a sleeve member 61 is interposed between the sensing member C in the sensing member installation hole 46 and the inner peripheral surface of the sensing member installation hole 46 facing the same.

[0037] Furthermore, in order to prevent or reduce problems such as the leaked resin coming into direct contact with the sensing member C and the sensing member C being overheated and malfunctioning, a pin member 62 is disposed at the inner opening of the sensing member installation hole 46. The pin member 62 is disposed in the sensing member installation hole 46 so as to be movable in the inner and outer directions, is displaced outward by the pressure of the leaked resin, and is configured to be able to smoothly transmit the pressure of the leaked resin to the sensing member C.

[0038] Also, vent holes 48 are formed in the heat insulating ring 4, each opening to the leaked resin accommodation space portion B and the outer peripheral surface 47 of the heat insulating ring 4, for connecting and communicating the leaked resin accommodation space portion B to the outside of the heat insulating ring 4. The vent holes 48 are vent holes for discharging the air extruded by the leaked resin that has entered the leaked resin accommodation space portion B to the outside of the leaked resin accommodation space portion B.

[0039] The vent holes 48 formed in the heat insulating ring 4 have a size sufficient to discharge the air in the leaked resin accommodation space portion B to the outside. On the other hand, the leaked resin that has leaked into the leaked resin accommodation space portion B has been cooled in the leaked resin accommodation space portion B and has an increased viscosity, and does not flow out to the outside through the vent holes 48.

[0040] The sensing member C may be equipped with a wireless module 7. The wireless module 7 is a module for performing wireless data communication, and is a module for realizing normal wireless communication methods such as Wi-Fi (registered trademark), Bluetooth (registered trademark), W-CDMA standard, LTE standard, LPWA (Low Power Wide Area) standard, etc.

[0041] 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 in a communicable manner. Further, a ROM (Read Only Memory) 62, a RAM (Random Access Memory) 63, an auxiliary storage device 64, and an output module 65 are electrically connected to the CPU 61 in a communicable manner.

[0042] The CPU 61 is electrically connected to the sensing member C via an A / D conversion unit 66 in a communicable manner. 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 sensing member C. The CPU 61 acquires the leakage resin signal transmitted along with the detection of the leakage resin from the sensing member C as a digital signal. A general-purpose wireless module may be attached or mounted to the CPU 61, the auxiliary storage device 64, the sensing member C, and the output module 65, and they may be electrically connected to communicate with each other wirelessly.

[0043] Examples of the auxiliary storage device 64 include an SSD (Solid State Drive) and an HDD (Hard Disk Drive). Examples of the output module 65 include a display, a speaker, and a mobile terminal device.

[0044] By loading a predetermined program onto the CPU 61 and the RAM 63, the sensing member C and the output module 65 are operated under the control of the CPU 61, and the leakage resin detection system D is realized by reading and writing data in the RAM 63 and the auxiliary storage device 64.

[0045] The resin leakage detection system D is provided with a resin leakage warning unit, and the resin leakage warning unit exhibits a predetermined function by executing a resin leakage warning program stored in the ROM 62 or the like under the control of the CPU 61.

[0046] Next, the usage instructions of the injection mold A will be described. To perform injection molding using the injection mold A, the fixed mold plate 1 and the moving mold plate are clamped to form a cavity therebetween, and then molten resin is supplied from the nozzle of the injection molding machine to the hot runner 31 of the manifold 3 via the sprue. While operating the valve pin 22, the molten resin is supplied into the cavity through the resin passage 21 and the gate portion 21a of the runner bushing 2 connected and communicating with the hot runner 31, and an injection molded product of a desired shape can be molded.

[0047] During injection molding, since the resin heated to a high temperature and in a molten state flows through the hot runner 31 of the manifold 3, the manifold 3 is heated by the molten resin and expands. On the other hand, in a state where injection molding is not being performed, since no molten resin flows through the hot runner 31 of the manifold 3, it is in a cooled state and the above expansion does not occur.

[0048] In addition, during injection molding, vibrations and the like caused by the driving of the injection molding machine, the clamping and opening of the fixed mold plate 1 and the moving mold plate, and the driving device for driving the valve pin 22 occur.

[0049] Thus, due to various factors occurring during injection molding, the screwing state of the bolts fixing the manifold 3 to the fixed mold plate 1 may become loose, and the fixing of the manifold 3 to the fixed mold plate 1 may become loose.

[0050] In such a state, the relative position between the manifold 3 and the runner bush 2 changes, the adhesion between the other end face 20b of the flange portion 20 of the runner bush 2 and the one end opening end face 32a of the hot runner 31 facing this is reduced, and a situation occurs where the molten resin leaks from the connection portion between the runner bush 2 and the manifold 3.

[0051] The adhesion between the contact portion 44 of the heat insulation ring 4 and the one end face 32 of the manifold 3 facing this also decreases. However, in the normal state, the adhesion between the contact portion 44 of the heat insulation ring 4 and the one end face 32 of the manifold 3 facing this is made higher than the adhesion between the other end face 20b of the flange portion 20 of the runner bush 2 and the one end opening end face 32a of the hot runner 31 facing this. Also, since the leaked resin preferentially enters and is accommodated in the leaked resin accommodation space portion B with a lower resistance than the interface between the heat insulation ring 4 and the one end face 32 of the manifold 3, the leaked resin does not leak outside the heat insulation ring 4.

[0052] The leakage of the molten resin from the connection portion between the runner bush 2 and the manifold 3 does not occur in a large amount at one time in the initial stage, but occurs gradually little by little. That is, after the leaked resin generated during the previous injection molding flows into and is accommodated in the leaked resin accommodation space portion B, it is cooled and becomes a deposit. And during the injection molding performed after this injection molding, leaked resin is similarly generated and flows into and is accommodated in the leaked resin accommodation space portion B. During injection molding, since the runner bush 2 and the manifold 3 are heated, the leaked resin already deposited in the leaked resin accommodation space portion B is also heated and softened. The leaked resins generated by multiple leaks are integrated while deforming according to the shape of the leaked resin accommodation space portion B as necessary, and are deposited in the leaked resin accommodation space portion B. And when the deposition of the leaked resin into the leaked resin accommodation space portion B progresses to a certain extent, the deposit of the leaked resin enters the sensing member arrangement hole 46 that opens into the leaked resin accommodation space portion B, and the sensing member C arranged in this sensing member arrangement hole 46 senses the leaked resin.

[0053] Further, the resin leakage accommodation space portion B is formed as an annular space so as to be a continuous space that surrounds the flange portion 20 of the runner bush 2 over its entire circumference, and the connection portions between the runner bush 2 and the manifold 3 are all accommodated in a state of being exposed within the resin leakage accommodation space portion B. Therefore, all of the resin leakage that leaks from the connection portions between the runner bush 2 and the manifold 3 is smoothly accommodated within the resin leakage accommodation space portion B and is surely detected by the detection member C.

[0054] When the detection member C detects the resin leakage, the detection member C transmits a resin leakage signal to the CPU 61. The CPU 61 that has received this resin leakage signal outputs a warning signal indicating that resin leakage has occurred to the output module 65, and the output module 65 outputs a warning signal such as a warning sound or a warning display.

[0055] Then, the administrator of the injection molding apparatus that has received the warning signal can easily stop the operation of the injection molding apparatus and check for resin leakage and repair the leakage point at an early stage, prevent damage to the injection molding apparatus caused by the resin leakage, and resume injection molding at an early stage.

[0056] In the above-described injection mold A for injection molding, one end surface 20a of the flange portion 20 of the runner bush 2 is received by the flange receiving surface 42 of the heat insulating ring 4, and the flange portion 20 of the runner bush is pressed toward the manifold 3 by this flange receiving surface 42, and the other end surface 20b of the flange portion 20 of the runner bush is pressure-bonded to the one end opening end surface 32a of the hot runner 31 in the manifold 3 in a watertight state. However, as shown in FIGS. 6 to 9, a connecting portion 24 is provided protruding from the protruding end portion of the runner bush 2, specifically, from the other end surface 20b of the flange portion 20, and a screw portion 24a formed on the outer peripheral surface of this connecting portion 24 is screwed into a connecting recess 33 formed in the one end opening of the hot runner 31 of the manifold 3 in a watertight manner, whereby the other end surface 20b of the flange portion 20 of the runner bush 2 is pressure-bonded to the one end surface 32 (the one end opening end surface 32a of the hot runner 31) of the manifold 3 in a watertight state. An injection mold A' may be used. The resin passage 21 of the runner bush 2 passes through the connecting portion 24 and is connected and communicated with the hot runner 31 of the manifold 3.

[0057] Also in the injection molding apparatus configured as described above, due to the expansion of the manifold 3 and the vibration during the driving of the above-described injection molding apparatus, etc., the screwing state of the bolts that fix the manifold 3 to the fixed mold plate 1 may become loose, and the fixing of the manifold 3 to the fixed mold plate 1 may become loose.

[0058] In such a state, the relative position between the manifold 3 and the runner bush 2 changes, the screwing state between the connecting portion 24 of the runner bush 2 and the connecting recess 33 of the manifold 3 becomes loose, the adhesion between the other end surface 20b of the flange portion 20 of the runner bush 2 and the one end surface 32 of the manifold 3 facing it decreases, and a situation occurs where molten resin leaks from the connecting portion between the runner bush 2 and the manifold 3.

[0059] Also in the injection mold A' for injection molding, a heat insulating ring 4' is interposed between the opposing surfaces of the manifold 3 and the fixed mold plate 1. The heat insulating ring 4' has the same structure as the above-described heat insulating ring 4 except that the insertion piece 43 and the contact portion 44 are not formed, and thus the same reference numerals are given and the description is omitted.

[0060] Also in the heat insulating ring 4', similarly to the above-described heat insulating ring 4, a space is formed between the outer peripheral surface 20c of the flange portion 20 of the runner bush 2 and the inner peripheral surface 45 of the heat insulating ring 4 facing the same, and this space is used as a leakage resin accommodation space portion B for receiving the leakage resin leaked from the connection portion between the manifold 3 and the runner bush 2. And the connection portion (connection interface) between the runner bush 2 and the manifold 3, that is, the connection portion between the other end surface 20b of the flange portion 20 of the runner bush 2 and the one end surface 32 of the manifold 3 facing the same is in a state of being entirely exposed and positioned within the leakage resin accommodation space portion B.

[0061] Also in the injection mold A' using the heat insulating ring 4', when the molten resin leaks from the connection portion (connection interface) between the runner bush 2 and the manifold 3, the leakage resin enters and is accommodated within the leakage resin accommodation space portion B to generate a deposit of the leakage resin, and the sensing member C disposed within the leakage resin accommodation space portion B senses this deposit of the leakage resin, and the administrator of the injection molding apparatus A' is notified that the leakage of the molten resin has occurred in the same manner as described above.

[0062] In the injection mold A', although the case where the heat insulating ring 4' in which the insertion piece 43 and the contact portion 44 are not formed is used has been described, a heat insulating ring in which either one or both of the insertion piece 43 and the contact portion 44 are formed may also be used.

Explanation of Signs

[0063] 1 Fixed mold plate 2 Runner bush 3 Manifold 31 Hot runner 4 Heat insulating ring 4a Other end surface of the heat insulating ring 4b One end surface of the heat insulating ring 5 Driving device 20 Flange portion of the runner bush 20a One end surface of the flange portion 20b Other end surface of the flange portion 21 Resin passage 21b Other end opening end surface of the resin passage 22 valve pin 41 through hole 42 flange receiving surface 43 insertion piece 44 abutting portion 45 inner peripheral surface 46 sensing member installation hole 48 ventilation hole A injection mold B leaked resin storage space portion C sensing member

Claims

【Claim 1】 A stationary mold plate provided with a runner bushing having a resin passage for supplying molten resin to a cavity, A manifold disposed on the stationary mold plate and provided with a hot runner communicating with the resin passage of the runner bushing, An injection mold comprising a heat insulating ring disposed between opposing surfaces of the stationary mold plate and the manifold, The heat insulating ring is formed in a cylindrical shape surrounding the connection portion between the manifold and the runner bushing while being crimped to the manifold. The heat insulating ring forms a leakage resin accommodation space portion for accommodating the leakage resin leaked from the connection portion between the manifold and the runner bushing by the opposing surfaces with the manifold and the runner bushing, and a sensing member for sensing the leakage resin is disposed in the leakage resin accommodation space portion. The runner bushing has a flange portion formed at the protruding end portion from the stationary mold plate and crimped to one end surface of the manifold. On the inner peripheral surface of the heat insulating ring, a flange portion receiving surface of the runner bushing is formed, and the flange portion of the runner bushing is crimped to the flange portion receiving surface of the heat insulating ring. The leakage resin accommodation space portion is formed by the outer peripheral surface of the flange portion, the inner peripheral surface of the heat insulating ring facing the outer peripheral surface of the flange portion, one end surface of the manifold and the flange portion receiving surface exposed between the outer peripheral surface of the flange portion and the inner peripheral surface of the heat insulating ring. An injection mold characterized by the above.

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