JP3684575B2 - Valve gate type mold equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve gate mold apparatus used for injection molding of a thermoplastic resin.
[0002]
[Problems to be solved by the invention]
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.
[0003]
FIG. 6 (A) 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 casing. The casing 2 is connected to a manifold (not shown) located on the left side of the figure, and is formed on a main body 3 of a mold body such as a fixed side template. It is inserted into the hole 4 made. In the casing 2, the flange 5 at the end on the manifold side and the fixing ring 7 which is a fixing member fixed to the outer peripheral surface of the end on the opposite gate 6 are fitted in the hole 4. As a result, it is supported by the main body portion 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 portion 3 of the mold body in other portions. Further, the inside of the casing 2 is a material passage 8 communicating with the gate 6. A valve pin (not shown) that passes through the material passage 8 and moves in the horizontal direction in the drawing to open and close the gate is provided. A heater 9 that heats the resin in the material passage 8 is provided on the outer peripheral surface of the 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 casing 2. The heater 9 is densely wound on both end sides of the casing 2, but is roughly wound on the intermediate portion. The reason will be described later. The number of turns of the heater 9 is 2 on the manifold side and 3 on the gate 6 side.
[0004]
FIG. 6B shows the result of measuring the temperature in the material passage 8. In the graph of the figure, the horizontal axis is the distance from the tip of the valve body 1 on the gate 6 side, and the vertical axis is the temperature. The temperature was measured for each point indicated by a black circle in the material passage 8. The broken line graphs a1 and a2 show the results when the set temperature for control of the valve body 1 and the manifold is set to 300 ° C. The solid line graphs b1 and b2 show the results when the set temperature is set to 250 ° C. As a result, dotted line graphs c1 and c2 are the results when the set temperature is set to 200 ° C. The mold cooling temperature was set to 10 ° C.
[0005]
As is apparent from the graphs a1, b1, and c1, the temperature tends to be low at both ends of the valve body 1 and high at the center. This is considered to be due to heat being transmitted from both ends in the central portion. In addition, the valve body 1 is in contact with only the both ends of the mold body 3 which is cooled in order to quickly solidify the resin in the product cavity. It is thought that another cause is that the heat escapes to the main body 3 of the body. In the illustrated valve device, in order to eliminate such temperature non-uniformity, the heater 9 is tightly wound at both ends of the valve body 1 while being roughly wound at the intermediate portion. As shown, the non-uniformity of temperature distribution is large.
[0006]
It is necessary to obtain a temperature that can ensure the fluidity of the resin at the lowest temperature portion of the material passage 8, that is, at both ends, but the temperature of the intermediate portion becomes excessively high. If the temperature is too high, the resin in the material passage 8 is burnt (causes black scorch), and the properties of the resin deteriorate.
[0007]
An object of the present invention is to provide a valve gate mold apparatus capable of reducing the temperature difference of molding materials in a material passage of a valve apparatus.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a valve gate type mold apparatus according to claim 1 is provided with a plurality of molds that are opened and closed with each other to form a product cavity between the molds and a material provided in the molds. A valve device that opens and closes a gate that communicates the passage with the product cavity, and the valve device holds a gap between the inner surface of the hole in the hole formed in the main body of the mold body. The valve body has a built-in valve body, a material passage leading to the gate is formed in the valve body, a first heater is provided on the outer periphery of the valve body, and the shaft of the valve body located on the gate side A second heater is provided at the tip of the direction, and the second heater is provided on the outer surface of the tip of the valve body facing the gap, and the sealing member is slidable on the inner peripheral surface of the material passage. Provided in The sealing member has a through hole molding material injected from said material passage passes, said by contact with the sealing member on the periphery of the gate by the pressure of the molding material injected from said material path it is configured ash of to seal the gap.
[0009]
At the time of molding, a plurality of molds are closed to form product cavities between the molds, the gate is opened, and the molding material is filled into the product cavities from the material passage through the gates. Next, the gate is closed by the valve device, and after the molding material in the product cavity is solidified, the mold is opened to take out the molding material in the product 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 first and second heaters. Here, the valve body is heated in the axial intermediate portion by the first heater, and further, the axial tip is heated by the second heater. As a result, the valve body is uniformly heated from its axially intermediate portion to the axial tip portion, so that the temperature difference of the molding material in the material passage of the valve body is reduced.
[0010]
Then, when the molten thermoplastic resin passes through the sealing member, the emission direction of the its pressure sealing member molding material, i.e., to block the gap by moving the gate side, and melted in the gap thermal Plastic resin does not flow. Thereby, since the 2nd heater and the molten thermoplastic resin do not contact, deterioration of the 2nd heater by heat is controlled.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a reference example of the valve gate mold apparatus of the present invention will be described with reference to FIGS. 1 and 2. Note that in the following description, the same reference numerals are given to portions common to FIG. 6A described above. 11 is a fixed mold, 12 is a movable mold, and these fixed mold 11 and movable mold 12 which are mold bodies move to each other in the illustrated vertical direction (mold opening / closing direction) in FIG. A product cavity 13 having a product shape is formed. The fixed mold 11 includes a metal fixed-side mold plate 3 as a main body, and a fixed-side mounting plate (not shown) fixed to the back side of the fixed-side mold plate 3 via a spacer block. A manifold 16 is provided between the fixed side mounting plate and the fixed side mold plate 3. The manifold 16 has a runner 17 that is a material passage formed therein, and the thermoplastic resin that is a molding material in the runner 17 is always melted by heating of a heater (not shown) provided in the manifold 16. To be kept. The fixed-side template 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 fixed mold 3, and the tip of the hole 4 on the movable mold 12 side is a gate 6 that communicates with the product cavity 13.
[0012]
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 body 1 having the axial direction of the mold opening / closing direction is incorporated in the hole 4 of the fixed-side mold plate 3. Most of the valve body 1 is constituted by a cylindrical casing 2, and one end portion of the casing 2 is a flange portion 5, and is fixed and supported between the manifold 16 and the stationary side template 3. ing. At the same time, the flange portion 5 is fitted in a step portion 23 formed at the end portion on the manifold 16 side in the hole portion 4. Further, a fixing ring 7 is fitted and fixed to the outer peripheral surface of the end portion on the gate 6 side in the casing 2, and this fixing ring 7 is a cylindrical fitting surface formed in the hole 4. 24 is fitted. Thereby, the gate 6 side portion of the casing 2 is supported by the fixed-side template 3. As described above, the valve main body 1 is in contact with the fixed-side template 3 at both ends, but is a fixing member between the outer surface of the valve main body 1 and the inner surface of the hole 4 in other portions. First and second gaps 25 and 26 that are blocked by the fixing ring 7 are formed. The first and second gaps 25 and 26 are connected to the gate 6 by the fixing ring 7 so that the first gap 25 located on the gate 6 side of the fixing ring 7 is in communication with the resin as a molding material. In the second gap 26, the inflow of the resin is blocked by the fixing ring 7 and becomes an air insulation layer.
[0013]
Further, the inside of the casing 2 is a material passage 8 that allows the runner 17 in the manifold 16 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 an end portion on the runner 17 side is a bent portion 31 that is bent. The bent portion 31 is formed by embedding the insert 32 in the casing 2. 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.
[0014]
A first heater 9 as a heating means for heating the material passage 8 and a substantially cylindrical metal heater cover 10 covering the first heater 9 from the outer peripheral side are fitted on the outer peripheral surface of the casing 2. Are combined. The first heater 9 has a band shape covering the casing 2. Furthermore, a second heater 41 is embedded at the tip of the valve body 2 in the axial direction. The second heater 41 is a linear heater. In addition, although the band-shaped thing was shown as the 1st heater 9 of this reference example, like the prior art example shown to FIG. 6 (A), what wound the linear heater may be used. Further, as shown in FIG. 3, the second heater 41 is embedded in a mounting substrate 42, which is a separate member from the valve body 2, except that the second heater 41 is embedded in the front end of the valve body 2 in the axial direction. The second heater 41 may be embedded in the tip of the valve body 2 in the axial direction through the mounting substrate 42. Although not shown, the casing 2 is provided with a temperature sensor along the inside of the first heater 9. This temperature sensor is located in the vicinity of the tip of the first heater 9 on the gate 6 side.
[0015]
The casing 2 incorporates a valve pin 36 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 36 is configured such that a gate closing portion 37 formed at a distal end portion on the gate 6 side is detachably fitted to the gate 6 to close the gate 6. Further, the valve pin 36 has the mold opening / closing direction as an axial direction, and an outer peripheral surface is slidably in contact with an inner edge of the support blade 33 of the casing 2 at all times. Thereby, the front-end | tip part by the side of the gate 6 of the valve pin 36 is supported. Further, the valve pin 36 is supported by a guide bush 38 fixed in the insert 32 at the end of the valve body 1 on the manifold 16 side. That is, the valve pin 36 is slidably penetrated through the guide bush 38. In order to connect the valve pin 36 to the driving device provided on the fixed side mounting plate, the valve pin 36 also penetrates the through hole 39 formed in the manifold 16.
[0016]
46 is a movable side mold plate of the movable mold 12, and this movable side mold plate 46 forms the product cavity 13 together with the fixed side mold plate 3.
[0017]
Although not shown, the stationary mold plate 3 and the movable mold plate 46 are formed with fluid passages through which a cooling fluid such as water for cooling the product cavity 13 passes.
[0018]
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 36 is moved away from the movable mold 12 as shown by a chain line in FIG. The gate 6 is opened by moving in the direction. 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 17 of the manifold 16 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 36 are fitted. After the resin is filled in the product cavity 13 in this way, after holding pressure, the valve pin 36 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 17 of the manifold 16. The first heater 9 in the section and the second heater 41 at the tip of the valve body 1 are always kept in a molten state by heating.
[0019]
As described above, in the valve body 1, but shows a tendency that the temperature is higher than both ends in the original its axial center portion, in the present embodiment, the valve body 1, the outer peripheral portion first The valve body 1 is heated by the heater 9, and further, the tip of the valve body 1 is heated by the second heater 41 embedded in the tip of the valve body 1, so that the valve body 1 can be moved from the axially intermediate portion of the valve body 1. Heat almost uniformly over the tip in the axial direction. Thereby, the temperature difference of the resin in the material passage 8 of the valve body 1 is reduced. Therefore, in order to ensure the fluidity of the resin in the material passage 38, 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.
[0020]
Moreover, the molten thermoplastic resin, which is a molding material at the time of molding, flows from the material passage 8 in the valve body 1 into the first gap 25 located closer to the gate 6 than the fixing ring 7 and becomes a resin heat insulating layer. The second heater 41 for heating the tip of the valve body 1 is embedded in the valve body 1 and does not directly contact the resin heat insulating layer flowing into the first gap 25. It is possible to suppress deterioration of the second heater 41 due to heat by suppressing the thermal influence.
[0021]
Here, the result of measuring the temperature in the material passage 8 will be described with reference to the graph of FIG. Although already described, the horizontal axis in the graph is the distance from the tip of the valve body 1 on the gate 6 side, and the vertical axis is the temperature. The temperature was measured for each point indicated by a black circle in the material passage 8. The broken line graphs a1 and a2 show the results when the set temperature for control of the valve body 1 and the manifold is set to 300 ° C. The solid line graphs b1 and b2 show the results when the set temperature is set to 250 ° C. As a result, dotted graphs c1 and c2 show the results when the set temperature is set to 200 ° C. The thin line graphs a1, b1, and c1 are the results of the conventional mold apparatus without the second heater 41 that heats the tip of the valve body 1, and the thick line graphs a2, b2, and c2 are It is the result of the mold apparatus of this reference example provided with the 2nd heater 41 which heats the front-end | tip part of the valve body 1. FIG. The mold cooling temperature was set to 10 ° C.
[0022]
When the second heater 41 for heating the tip of the valve body 1 is not provided (graphs a1, b1, c1) and the second heater 41 is provided (graphs a2, b2, c2), the second It is obvious that the temperature difference between the intermediate portion in the axial direction of the valve body 1 and the tip end side is smaller in the case where the heater 41 is present, and the temperature distribution in the material passage 8 is more uniform.
[0023]
4 and 5 show a real施例of the present invention, the same reference numerals are given to portions having the reference example and the same function, only different portions will be described. In the above reference example, the second heater 41 is embedded in the tip of the valve body 1 in the axial direction so as to avoid contact with the molten resin flowing into the first gap 25. However, the valve body 1 is manufactured. In terms of processing, it is easier to process by providing a band-shaped heater exposed on the outer surface of the valve body 1. Therefore, in the present embodiment, the band-shaped second heater 45 is assembled on the outer surface of the distal end of the valve body 1 so as to be exposed to the outside. A sealing ring 51 as a sealing member for closing the first gap 25 is provided at the tip of the valve body 1 on the gate 6 side. The outer surface of the sealing ring 51 has a cylindrical shape as a whole so as to be fitted into the tip hole portion 52 of the valve body 1. Further, the sealing ring 51 is slightly shorter than the distance from the lower end edge of the support blade 33 integrally formed in the valve body 1 to the fixed side mold plate 3, and between the support blade 33 and the fixed side mold plate 3. 1 is slidably assembled along the tip hole 52 of the valve body 1. Further, the sealing ring 51 is formed with a through hole 53 of the valve pin 36. The through hole 53 is formed with a tapered surface 54 that opens to the material passage 8 side and narrows toward the gate 6 side. A tip opening 55 on the small diameter side of the tapered surface 54 communicates with the gate 6. Yes. A tip opening 55 of the sealing ring 51 is formed to have the same diameter as the gate 6. When the molding material injected from the material passage 8 side during molding passes through the through-hole 53 of the sealing ring 51 during molding, the sealing ring 51 moves to the injection direction of the molding material, that is, the gate 6 side. Then, the front end surface of the sealing ring 51 comes into contact with the peripheral edge of the gate 6. As a result, the first gap 25 is blocked and the molten thermoplastic resin is prevented from flowing into the first gap 25.
[0024]
Therefore, in this embodiment, the second heater 45 can be easily attached to the valve body 1 by forming the band-shaped second heater 45 on the outer surface of the tip end portion of the valve body 1. Molding process is easy. Further, the sealing ring 51 is slidably assembled at the tip of the valve body 1 so that when the molten thermoplastic resin passes through the through-hole 53 of the sealing ring 51, the sealing ring 51 is molded by the pressure. The thermoplastic resin does not flow into the first gap 25 because the first gap 25 is blocked by moving toward the injection direction, that is, the gate 6 side. For this reason, even if the second heater 45 is exposed and attached facing the first gap 25, it does not come into contact with the molten thermoplastic resin. Therefore, it is possible to prevent the molten thermal influence of the second heater 45 by the thermoplastic resin can be suppressed and deterioration of the second heater 41 by heat.
[0025]
In addition, this invention is not limited to the said Example, A various deformation | transformation implementation is possible. For example, the basic structure of the valve gate mold apparatus and the shape of the sealing ring 51 to be assembled to the tip of the valve body 1 are not limited to the above-described embodiment, and may be appropriately selected.
[0026]
【The invention's effect】
According to the valve gate mold apparatus of the first aspect of the invention, the central portion in the axial direction of the valve body is heated by the first heater, and the tip portion of the valve body is heated by the second heater. Thereby, the axial direction intermediate part of a valve main body and the axial direction front-end | tip part of the valve main body 1 can be heated substantially uniformly, and the temperature difference of the resin in the material channel | path of a valve main body can be reduced. Therefore, it is possible to prevent a portion in which the temperature of the resin is excessively high in this material passage from occurring, to prevent the resin from being burnt, and to prevent deterioration of the properties of the resin. It can prevent that the characteristic of a material falls.
[0027]
Furthermore, since the gap is blocked by the pressure of the molten thermoplastic resin at the time of molding, the second heater and the molten thermoplastic resin are not in direct contact. For this reason, the thermal influence which a 2nd heater receives can be suppressed and degradation of the 2nd heater by heat can be prevented.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a reference example of a valve gate type mold apparatus of the present invention.
FIG. 2 is an enlarged sectional view of the gate part.
FIG. 3 is an enlarged cross-sectional view of a gate portion showing a modification of the reference example of the second heater of the present invention.
4 is a longitudinal sectional view showing the actual施例valve gate type mold apparatus of the present invention.
FIG. 5 is an enlarged sectional view of the gate part.
6A and 6B show temperature measurement results, where FIG. 6A is a longitudinal sectional view of a valve device, and FIG. 6B is a graph showing temperature.
[Explanation of symbols]
1 Valve body 3 Fixed side template (Main body)
4 hole 8 material passage 9 first heater
11 Fixed type
12 Movable type
13 Product cavity
17 Runner (material passage)
21 Valve device
25, 26 First and second gaps
41, 45 Second heater
51 Seal ring
53 through hole

Claims (1)

A plurality of mold bodies that open and close each other and form a product cavity between the mold cavities, and a valve device that opens and closes a gate that communicates a material passage provided in the mold body with the product cavity. And a valve body incorporated in the hole formed in the body of the mold body with a gap between the hole and the inner surface of the hole, and a material passage leading to the gate is formed in the valve body. and, wherein the outer periphery of the valve body provided with a first heater, the second heater provided at the axial tip portion of the valve body located on the gate side, the second heater faces the gap A sealing member is slidably provided on the inner peripheral surface of the material passage, and the sealing member is a through-hole through which a molding material injected from the material passage passes. The And, valve gate type mold apparatus, wherein the configuration and kite so as to seal the gap by contact with the sealing member on the periphery of the gate by the pressure of the molding material injected from said material path .

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