JP4343001B2 - Valve gate type mold equipment - Google Patents

Description

The present invention relates to a valve gate mold apparatus used for injection molding of a thermoplastic resin, for example.

In a hot runner mold apparatus that heats the resin that is the molding material in the material passage to the gate to the product cavity and keeps it in a molten state at all times, a valve gate mold apparatus that mechanically opens and closes the gate with a valve pin is known. ing. The hot runner mold apparatus is intended to increase the molding efficiency, and the gate is closed to prevent the resin from leaking from the gate when the mold is opened.

FIG. 3 shows an example of the valve body 1 of the valve device in this type of valve gate mold apparatus. In the figure, reference numeral 2 denotes a cylindrical valve casing. The valve casing 2 is connected to a manifold located on the left side of the figure, and has a hole formed in a main body 3 of a mold body such as a fixed-side mold plate. 4 to be inserted. In the valve casing 2, the flange portion 5 at the end portion on the manifold side and the fixing ring 7 fixed to the outer peripheral surface of the end portion on the opposite gate 6 side are fitted in the hole portion 4. Thus, it is supported by the main body 3 of the mold body, and a gap forming a heat insulating layer is formed between the valve main body 1 and the main body section 3 of the mold body in other portions. Further, the inside of the valve casing 2 is a material passage 8 communicating with the gate 6. And the valve pin which penetrates this material channel | path 8 and moves to the up-down direction of illustration and opens and closes a gate is provided. A heater 9 for heating the resin in the material passage 8 is provided on the outer peripheral surface of the valve casing 2, and a cylindrical heater cover 10 that covers the heater 9 from the outer peripheral side is fixed. The heater 9 is a linear heater and is wound around the outer peripheral surface of the valve casing 2. The heater 9 is densely wound at both ends of the valve casing 2, but is roughly wound at the intermediate portion (for example, Patent Document 1).

In the valve gate mold apparatus as described above, the temperature of the valve casing 2 of the valve body 1 tends to be low at both ends of the valve casing 2 and high at the center. This is because heat is transmitted from both end sides of the valve casing 2 at the central portion, and the valve casing 2 has both ends with respect to the body portion 3 of the mold to be cooled in order to quickly solidify the resin in the product cavity. This is considered to be caused by heat escaping from the valve casing 2 to the body portion 3 of the mold body through the contact portion. In order to eliminate such temperature non-uniformity, in the illustrated valve device, as described above, the heater 9 is tightly wound at both ends of the valve casing 2 and is roughly wound at the intermediate portion. At present, the distribution is highly uneven. Therefore, it is necessary to obtain a temperature at which the fluidity of the resin can be secured even at the lowest temperature portion of the material passage 8, that is, at both ends, but as a result, the temperature of the intermediate portion becomes excessively high. If the temperature is too high, there is a problem that the resin in the material passage 8 is burnt (causes a black burn), and the properties of the resin may be deteriorated.

Therefore, in the valve device (Patent Document 1), a heat transfer body is provided between the valve main body and the mold body at an axially intermediate portion of the valve main body, and the main body of the mold body is passed through the heat transfer body. Heat is dissipated to the part.
JP 2002-331552 A

In the above prior art valve device, when the heater 9 is tightly wound at both ends of the valve casing 2 and is roughly wound at the middle portion, the middle portion becomes a cavity, and this cavity becomes an air insulation layer and is located in the middle of the material passage. The temperature of the part cannot be lowered sufficiently. On the other hand, in the case where a heat transfer body is provided between the valve body and the mold body in the axial middle portion of the valve body, heat is radiated from the valve body to the body body of the mold body through the heat transfer body. The temperature of the axially intermediate part of the main body decreases, and the temperature difference of the molding material in the material passage of the valve main body is reduced, but heat loss is generated because the heat of the heater is released to the valve body by the heat transfer body. .
The present invention is intended to solve such problems, and an object thereof is to provide a valgate type mold apparatus that can reduce the temperature difference of the molding material in the material passage of the valve apparatus.

The valve gate type mold apparatus according to claim 1, wherein a plurality of mold bodies that open and close each other and form a product-shaped cavity therebetween when the mold is closed, and a gate that communicates a material passage provided in the mold body with the cavity. A valve device that opens and closes the valve body, and the valve device has a valve body that is incorporated in a hole formed in the main body of the mold body with a gap between the inner surface of the hole, In this valve body , a material passage leading to the gate is formed, and in the valve gate type mold apparatus provided with a heater on the outer peripheral portion of the valve main body, the gate side and the opposite gate side of the outer peripheral portion of the valve main body In addition to providing a heater, a hollow portion is provided in the middle in the axial direction, and a metal heat transfer body is provided in this hollow portion so as to contact the valve body, and a gap is provided between the heat transfer body and the inner surface of the hole. Provided A.

Further, in the valve gate mold apparatus according to claim 2, the heat transfer body has a cylindrical shape.

The valve gate mold apparatus according to claim 1 is provided with a heater cover on the outer periphery of the heater and the heat transfer body so as to be in contact with the heat transfer body, and a gap is formed between the heater cover and the inner surface of the hole. And an engaging portion that engages with the heater cover is provided on the heat transfer body.

In the valve gate mold apparatus according to claim 3, the heat transfer body is made of pre-hardened steel.

According to the configuration of the first aspect, at the time of molding, a plurality of molds are closed to form a product-shaped cavity between the molds, the gate is opened, and molding is performed from the material passage into the product cavity via the gate. Fill material. Next, the gate is closed by the valve device, and after the molding material in the cavity is solidified, the mold is opened to take out the molding material in the cavity, that is, the molded product. Thereafter, the mold is closed again, and the above molding cycle is repeated. Throughout the entire molding cycle, the molding material in the material passage of the valve body is always kept in a molten state by heating the heater. Then, in the valve body which is provided on the outer peripheral portion of the heater, but shows a tendency that the temperature is higher than both ends in the original that between in axial section, the heat of the intermediate portion and the inner surface of the hole from the heat conductor The temperature of the intermediate portion in the axial direction of the valve main body is lowered, and the temperature difference of the molding material in the material passage of the valve main body is reduced. In this case, the heat transfer body is not in contact with the main body portion of the mold body, and the gap between the main body portion becomes a heat insulating layer, so that heat is not released unnecessarily to the main body portion, while performing efficient heating. The temperature difference of the molding material in the material passage can be reduced.

Moreover, according to the structure of Claim 2, heat escapes to the clearance gap between the cylindrical heat-transfer body and the inner surface of the said hole.

Moreover, according to the structure of Claim 1 , a heat-transfer body can be positioned to an axial direction by a heat-transfer body engaging with a heater cover.

According to the configuration of claim 3 , pre-hardened steel is a hardened steel material that can be used without being heat-treated only by cutting, so that the material cost can be reduced. Pre-hardened steel is not easily rusted if it is excellent in heat resistance and corrosion resistance, and is suitable as a heat transfer body used in a valve body.

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below do not limit the contents of the present invention described in the claims. In addition, all the configurations described below are not necessarily essential requirements of the present invention. In each embodiment, an unprecedented valve gate type mold apparatus is obtained by adopting a valve gate type mold apparatus different from the conventional one, and the valve gate type mold apparatus is described respectively.

Hereinafter, a first embodiment of a valve gate mold apparatus of the present invention will be described with reference to FIGS. In the following description, the same reference numerals are given to the portions common to FIG. 3 described above. In the figure, 11 is a fixed mold, 12 is a movable mold, and these fixed mold 11 and movable mold 12, which are mold bodies, move in the vertical direction (mold opening / closing direction) in FIG. Sometimes a product-shaped cavity 13 is formed between them. The fixed mold 11 includes a main body 3 composed of a metal fixed-side mold plate 3A and a fixed-side receiving plate 3B, and a fixed-side mounting plate (not shown) fixed to the back side of the main body 3 via a spacer block. ) And a manifold 14 is provided between the fixed-side mounting plate and the main body 3. A runner 15 that is a material passage is formed in the manifold 14, and the thermoplastic resin that is a molding material in the runner 15 is always melted by heating of a heater (not shown) provided in the manifold 14. It is supposed to be kept in a state. The main body 3 may be constituted by a plurality of members by adding a fixed side receiving plate or a gate bush. Further, a hole 4 is formed through the main body 3, and the tip of the hole 4 on the movable mold 12 side is a gate 6 communicating with the cavity 13.

Further, the fixed mold 11 incorporates a valve device 21 for opening and closing the gate 6. Next, the configuration of the valve device 21 will be described. A valve main body 1 having the axial direction of the mold opening / closing direction is incorporated in the hole 4 of the main body 3. Most of the valve body 1 is constituted by a cylindrical valve casing 2, and one end portion of the valve casing 2 is a flange portion 5 which is fixed and supported between the manifold 14 and the body portion 3. ing. At the same time, the flange portion 5 is fitted to a step portion 22 formed at the end portion on the manifold 14 side in the hole portion 4. Further, a fixing ring 7 is fitted and fixed to the outer peripheral surface of the end of the valve casing 2 on the gate 6 side, and the fixing ring 7 is formed in a columnar shape formed in the hole 4. The surface 23 is fitted. Thereby, the gate 6 side portion of the valve casing 2 is supported by the main body 3. As described above, the valve main body 1 is in contact with the main body 3 at both ends, but in other portions, the heat-insulating gap 24, between the outer surface of the valve main body 1 and the inner surface of the hole 4, 25 is formed. The gaps 24 and 25 are blocked by the fixing ring 7. The gap 24 on the gate 6 side of the fixing ring 7 is a resin heat insulating layer that communicates with the gate 6 and into which resin as a molding material flows. The gap 25 on the side becomes an air heat insulating layer.

Further, the inside of the valve casing 2 is a material passage 8 that allows the runner 15 in the manifold 14 to communicate with the gate 6. The material passage 8 has a substantially cylindrical shape with the mold opening / closing direction as an axial direction, but the end portion on the runner 15 side is a bent portion 31 that is bent. In addition, three or more support blades 33 extending in the mold opening / closing direction are formed on the inner peripheral surface of the distal end portion of the material passage 8 on the gate 6 side.

Further, heaters 9, 9A are provided on the outer peripheral surface of the valve casing 2 at both axial ends of the valve casing 2, and a substantially cylindrical metal heater cover 10 is provided from the outer peripheral side of the heaters 9, 9A. And a hollow portion 35 is formed between the heaters 9 and 9A in the heater cover 10. A substantially cylindrical heat transfer body 36 is provided in the hollow portion 35, and the outer periphery of the heat transfer body 36 is fitted in a state where the inner periphery is in contact with the outer periphery of the valve casing 2. An engaging portion 37 having a large diameter is formed at the top. The heater cover 10 includes a gate-side cover portion 38 and an anti-gate-side cover portion 39 which are divided into a gate side and an anti-gate side, and the anti-gate side of the gate-side cover portion 38 is a large-diameter portion having a large diameter. 38A is formed, and a step portion 39A in which the end portion of the large diameter portion 38A is fitted is formed at the end portion of the anti-gate side cover portion 39, and the end portion of the large diameter portion 38A is outside the step portion 39A. When the heater cover 9 is assembled by fitting, an engagement recess 40 into which the engagement portion 37 is fitted is formed on the center side in the axial direction of the heater cover 9, and the outer periphery of the engagement portion 37 is inserted in the fitted state. The both ends of the engaging portion 37 in the axial direction are in contact with the cover portions 38 and 39, in contact with the inner periphery of the engaging recess 40.

The heat transfer body 36 is made of metal and is preferably made of pre-hardened steel having excellent corrosion resistance. For example, stainless-based pre-hardened steel PSL (trade name, manufactured by Hitachi Metals, Ltd.) is used.

Further, although not shown, the valve casing 2 is provided with a temperature sensor along the inside of the heater 9. This temperature sensor is located near the tip of the heater 9 on the gate 6 side. The heaters 9 and 9A may be configured such that the linear heater is densely wound at both axial ends of the valve casing 2 and is coarsely wound at the axially intermediate portion.

The valve casing 2 incorporates a valve pin 51 as a valve body that moves in the mold opening and closing direction by driving of a driving device such as a hydraulic cylinder device (not shown) provided on the fixed mounting plate. The valve pin 51 is configured such that a gate closing portion 52 formed at the distal end portion on the gate 6 side is detachably fitted to the gate 6 to close the gate 6. Further, the valve pin 51 has the mold opening / closing direction as an axial direction, and an outer peripheral surface thereof is slidably in contact with the inner edge of the support blade 33 of the valve casing 2 at all times. Thereby, the tip of the valve pin 51 on the gate 6 side is supported. Further, the valve pin 51 is supported by a guide bush 53 fixed in the insert 32 at the end of the valve body 1 on the manifold 14 side. That is, the valve pin 51 passes through the guide bush 53 so as to be slidable. In order to connect the valve pin 51 to a driving device provided on the fixed side mounting plate, the valve pin 51 also penetrates the through hole 54 formed in the manifold 14. 55 is a movable side mold plate of the movable mold 12, and this movable side mold plate 55 forms the product cavity 13 together with the main body 3. Although not shown, the main body 3 and the movable side mold plate 55 are formed with fluid passages through which a cooling fluid such as water for cooling the product cavity 13 passes.

Next, the operation of the above configuration will be described. First, the fixed mold 11 and the movable mold 12 are closed, and a product cavity 13 is formed between the fixed mold 11 and the movable mold 12, and then the valve pin 51 is moved away from the movable mold 12 to open the gate 6. To do. Then, a molten thermoplastic resin, which is a thermoplastic molding material, is injected into the fixed mold 11 from the injection molding machine. This resin flows through the runner 15 of the manifold 14 and the like, and further flows into the product cavity 13 from the gate 6 through the material passage 8 in the valve body 1 and the support blades 33 in which the valve pins 51 are fitted. After the resin is filled in the product cavity 13 in this way, after holding pressure, the valve pin 51 moves toward the movable mold 12 as shown by the solid line in FIG. Close the gate 6. The resin in the product cavity 13 is actively cooled by passing a cooling fluid through the fluid passage. Then, after the resin in the product cavity 13 is cooled and solidified, the fixed mold 11 and the movable mold 12 are opened, and the resin in the product cavity 13, that is, the molded product is taken out. Thereafter, the mold is closed again, and the above molding cycle is repeated. Through the entire molding cycle, the resin in the material passage 8 of the valve body 1 is the outer periphery of the valve body 1 in the same manner as the resin in the runner 15 of the manifold 14. It is always kept in a molten state by heating the heaters 9 and 9A in the section.

As described above, in the valve body 1, the temperature tends to be higher than the both ends at the center in the axial direction. because provided 36, by this heat conductor 36 heat the intermediate portion of the valve casing 2 escapes into the gap 25 between the inner surface of the heater cover 10 and the hole 4, the temperature of the axially intermediate portion of the valve body 1 The temperature difference of the molding material in the material passage 8 of the valve body 1 is reduced. Further, if attention is paid only to the direct heating by the heaters 9 and 9A, the intermediate portion in the axial direction of the valve casing 2 tends to transmit less heat energy than the both end portions, and the main body portion 3 which is the main body portion of the mold body is shown. Heat dissipation from both ends caused by contact of the valve casing 2 at both ends is offset, and as a result, the temperature difference of the resin in the material passage 8 of the valve casing 2 is reduced. Therefore, in order to ensure the fluidity of the resin in the material passage 8, it is possible to prevent a portion where the temperature of the resin is excessively high in the material passage 8, and to prevent the resin from being burned. It can prevent that the characteristic of this resin falls.

Thus, in the present embodiment, corresponding to claim 1, a plurality of fixed molds 11 and movable molds 12 which are opened and closed with each other and form product-shaped cavities 13 between the molds, and the fixed molds. 11 is provided with a valve device 21 for opening and closing the gate 6 for communicating the material passage 8 provided in 11 with the cavity 13. The valve device 21 is provided in the hole portion 4 formed in the main body portion 3 of the fixed mold 11. The valve body 1 is assembled with a gap 25 between the inner surface of the section 4 and a material passage 8 leading to the gate 6 is formed in the valve body 1, and a heater is formed on the outer periphery of the valve body 1. In the valve gate type mold apparatus provided with 9, 9A, heaters 9, 9A are provided on the gate 6 side and the counter-gate 6 side of the outer periphery of the valve body 1, and a hollow portion 35 is provided in the axial intermediate portion. A heat transfer body 36 is provided in the cavity 35, and the heat transfer body 36 and the hole 25 Since the gap 25 is provided between the inner surface and the inner surface, at the time of molding, the fixed mold 11 and the movable mold 12 are closed, a cavity 13 is formed between the fixed mold 11 and the movable mold 12, and the gate 6 is opened. The molten resin as the molding material is filled into the cavity 13 through the gate 6. Subsequently, the gate 6 is closed by the valve device 21. Further, after the molding material in the cavity 13 is solidified, the mold is opened to take out the molding material in the cavity 13, that is, the molded product. Thereafter, the mold is closed again and the above molding cycle is repeated. Throughout the entire molding cycle, the molding material in the material passage 8 of the valve body 1 is always kept in a molten state by heating the heaters 9 and 9A. Then, in the valve body 1 which is provided on the outer periphery of the heater 9, 9A, shows a tendency that the temperature is higher than both ends in the original its axial central portion, the hole heat of the intermediate portion from the heat transfer member 36 By escaping into the clearance 25 between the inner surface of the valve body 4, the temperature of the intermediate portion in the axial direction of the valve body 1 is lowered, and the temperature difference of the molding material in the material passage 8 of the valve body 1 is reduced. In this case, the heat transfer body 36 is not in contact with the main body portion 3 of the fixed mold 11 of the mold body, and the gap 25 between the heat transfer body 36 and the main body portion 3 becomes a heat insulating layer, so that heat is unnecessarily escaped to the main body portion 3. The temperature difference of the molding material in the material passage 8 can be reduced while performing efficient heating.

In this way, in this embodiment, the heat transfer body 36 has a cylindrical shape corresponding to claim 2, and therefore, the space between the cylindrical heat transfer body and the inner surface of the hole 4 via the heater cover 10. Heat escapes into the gap 25.

In this way, in this embodiment, corresponding to claim 1 , the heater cover 10 is provided on the outer periphery of the heaters 9, 9 </ b> A and the heat transfer body 36, and the heater cover 10 is disposed between the heater cover 10 and the inner surface of the hole 4. Since the clearance 25 is provided and the engaging portion 37 that engages with the heater cover 10 is provided in the heat transfer body 36, the heat transfer body 36 engages with the heater cover 10, whereby the valve body 1 of the heat transfer body 36 is in the axial direction. Can be positioned.

In this way, in this embodiment, in correspondence with claim 3 , the heat transfer body 36 is made of pre-hardened steel. Therefore, the pre-hardened steel is a hardened steel material and is used without being heat-treated only by cutting. As a result, material costs can be reduced. Pre-hardened steel is not easily rusted if it has excellent heat resistance and excellent corrosion resistance, and is suitable as a heat transfer body used for the valve body 1.

Further, as an effect of the embodiment, since the heater cover 10 is divided into a plurality of parts and fitted onto the cylindrical heat transfer body 36, the heaters 9, 9A, the heat transfer body 36, and the valve casing of the heater cover 10 are provided. Assembling work to 9 can be performed easily.

In addition, this invention is not limited to the said Example, A various deformation | transformation implementation is possible. For example, heat transfer body as long as it has a heat resistance that corresponds to the operating temperature conditions of the valve body 1, can be used various materials.

It is a longitudinal cross-sectional view which shows Example 1 of this invention. FIG. 2 is an enlarged longitudinal sectional view around the heat transfer body. It is a longitudinal cross-sectional view of the conventional valve gate type mold apparatus.

DESCRIPTION OF SYMBOLS 1 Valve body 2 Valve casing 3 Body part 4 Hole part 6 Gate 8 Material passage 9, 9A Heater
10 Heater cover
11 Fixed type
12 Movable type
13 cavity
21 Valve device
25 Clearance
35 cavity
36 Heat transfer body
37 Engagement part
51 Valve pin

Claims (3)

A plurality of molds that open and close each other to form a product-shaped cavity when the mold is closed, and a valve device that opens and closes a gate that communicates a material passage provided in the mold with the cavity. Has a valve body incorporated in the hole formed in the body of the mold body with a gap between the inner surface of the hole and a material passage leading to the gate in the valve body . In the valve gate type mold apparatus in which a heater is provided on the outer periphery of the valve body, the heater is provided on the gate side and the opposite gate side of the outer periphery of the valve body, and a hollow portion is provided in the middle in the axial direction. In this hollow portion, a metal heat transfer body is provided so as to be in contact with the valve body , a gap is provided between the heat transfer body and the inner surface of the hole , and the outer periphery of the heater and the heat transfer body is provided . The heat transfer body and The heater cover provided to the valve gate, characterized in that the heater cover and a gap is provided between the inner surface of the hole, it is provided an engaging portion engaged with the heater cover to the heat transfer Mold device. The valve gate mold apparatus according to claim 1, wherein the heat transfer body has a cylindrical shape. The valve gate mold apparatus according to claim 1 or 2, wherein the heat transfer body is made of pre-hardened steel.

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