JP3684574B2 - 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. 3 (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 portion 5 at the end portion on the manifold side and the fixing ring 7 that is a ring member fixed to the outer peripheral surface of the end portion on the opposite gate 6 side are fitted into the hole portion 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. 3B 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 apparent from the graphs a1, b1, and c2, 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. It has a built-in valve body, a material passage for the molding material 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 tip of the valve body is heated A second heater is provided in the mold body , a ring member is fitted to the periphery of the tip of the valve body, and a cylindrical fitting is fitted to the ring member of the valve body on the inner bottom of the hole. Forming a mating surface The ring member is fitted to the fitting surface to support the tip end portion of the valve body, and the first and second portions cut off by the ring member between the valve body and the inner surface of the hole portion. A gap is formed, and the first gap located on the gate side is a heat insulating layer that communicates with the gate and into which the molding material flows, and the second gap is an air heat insulating layer, and the second gap This heater is provided in the vicinity of the fitting surface .
[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 axially distal end side of the valve body is indirectly heated by the second heater provided inside the mold body. 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]
The valve body is in partial contact with the fitting surface of the mold body at the tip, and heat escapes from the valve body to the mold body through this fitting surface, but the second heater is in the vicinity of the fitting surface. Therefore, the heat of the second heater is transmitted to the tip of the valve body via the ring member that is fitted to the fitting surface. As a result, the temperature drop at the tip of the valve body can be suppressed, and the valve body is heated uniformly from its axially intermediate portion to the axially tip portion. The temperature difference is reduced .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the valve gate mold apparatus of the present invention will be described with reference to FIGS. Note that in the following description, the same reference numerals are given to the portions common to FIG. 3A 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. A fixing ring 7 as a ring member is fitted and fixed to the outer peripheral surface of the end portion on the gate 6 side of the casing 2, and the fixing ring 7 is formed on the inner bottom portion 4 </ b> A of the hole portion 4. The cylindrical fitting surface 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 thereof, but in the other portions, the fixing ring 7 is interposed between the outer surface of the valve main body 1 and the inner surface of the hole 4. First and second gaps 25 and 26 that are blocked by the above 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. The second gap 26 becomes an air heat insulating layer by blocking the inflow of the resin by the fixing ring 7.
[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. Further, a second heater 41 is embedded in the fixed mold 11 so as to be positioned on the axial front end side of the valve body 1. The second heater 41 is linear, and indirectly heats the front end of the valve body 1 in the axial direction. That is, the valve body 1 is in contact with the fixed mold 11 only at the lower end of the valve body 1, and heat escapes from the valve body 1 to the fixed mold 11 through the fixed ring 7, so that the second heater 41 is fixed. By embedding in the vicinity of the fitting surface 24 of the ring 7, the heat of the second heater 41 is transmitted to the distal end portion of the valve body 1 via the fixing ring 7.
[0015]
In addition, although the band-shaped thing was shown as the 1st heater 9 of a present Example, like the prior art example shown to FIG. 3 (A), what wound the linear heater may be used. 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.
[0016]
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.
[0017]
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.
[0018]
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.
[0019]
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.
[0020]
As described above, in the valve body 1, the temperature tends to be higher than the both end sides at the central portion in the axial direction, but in the present embodiment, the valve body 1 has the outer peripheral portion of the first portion. The tip of the valve body 1 is heated indirectly by the second heater 41 which is heated by the heater 9 and is embedded in the fixed mold 11 in the vicinity of the fitting surface 24 fitted to the outer periphery of the tip. That is, the valve body 1 is in contact with the fixed mold 11 only at the front end of the valve body 1, and heat escapes from the valve body 1 to the fixed mold 11 through the fixed ring 7, compared to the middle part of the valve body 1. Although the temperature of the tip of the valve body 1 is lowered, by heating the vicinity of the fitting surface 24 of the fixed mold 11 by the second heater 41, the heat passes through the fixing ring 7 that fits the fitting surface 24. It is transmitted to the tip of the valve body 1. As a result, the tip end side of the valve body 1 is indirectly heated by the second heater 41 so that the valve body 1 can be heated almost uniformly from the axially intermediate portion of the valve body 1 to the tip portion of the valve body 1 in the axial direction. it can. 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. Further, since the heat of the second heater 41 is transmitted to the tip of the valve body 1 through the fixing ring 7 fitted to the fitting surface 24, the tip of the valve body 1 is efficiently heated by the second heater 41. It becomes possible.
[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 distal end side of the valve body 1 in proximity to the fitting surface 24. Graphs a2, b2, and c2 are the results of the mold apparatus of the present example in which the second heater 41 that heats the distal end side of the valve body 1 in the vicinity of the fitting surface 24 is provided. The mold cooling temperature was set to 10 ° C.
[0022]
When there is no second heater 41 (graphs a1, b1, and c1) that heats the front end side of the valve body 1 close to the fitting surface 24, and when there is the second heater 41 (graphs a2, b2, In comparison with c2), in the case where the second heater 41 is provided, the temperature difference between the axial intermediate portion and the tip side of the valve body 1 is smaller, and the temperature distribution in the material passage 8 is more uniform. It is clear that
[0023]
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, the number of second heaters embedded in the fixed mold, and the like are not limited to the above embodiment, and may be selected as appropriate.
[0024]
【The invention's effect】
According to the valve gate mold apparatus of the first aspect of the present invention, the axial center portion of the valve body is heated by the first heater, and the tip portion of the valve body is indirectly heated by the second heater. The 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. And since the heat of a 2nd heater is efficiently transmitted to the front end side of a valve main body through a ring member from a fitting surface, the axial direction front-end | tip part of the valve main body from which heat escapes can be heated efficiently .
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a first embodiment of a valve gate mold apparatus according to the present invention.
FIG. 2 is an enlarged sectional view of the gate part.
3A and 3B show temperature measurement results, where FIG. 3A is a longitudinal sectional view of a valve device, and FIG. 3B is a graph showing temperature.
[Explanation of symbols]
1 Valve body 3 Fixed side template (Main body)
4 hole 8 material passage 7 fixing ring (ring member)
9 First heater
11 Fixed type
12 Movable type
13 Product cavity
17 Runner (material passage)
21 Valve device
24 Mating surface
25 First gap (gap)
26 Second gap (gap)
41 Second heater

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 material for the molding material having 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 mold, and leading to the gate in the valve body. A passage is formed, a first heater is provided on the outer periphery of the valve body, a second heater for heating the tip of the valve body is provided in the mold body, and a ring is provided around the tip of the valve body. The valve body is formed by fitting a member, forming a cylindrical fitting surface that fits with the ring member of the valve body at the inner bottom of the hole, and fitting the ring member with the fitting surface. Support the tip of The first gap and the second gap blocked by the ring member are formed between the valve body and the inner surface of the hole, and the first gap located on the gate side communicates with the gate. The valve gate mold is characterized in that the molding material flows into the heat insulating layer, the second gap is an air heat insulating layer, and the second heater is provided in the vicinity of the fitting surface. apparatus.

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