JP2003245953A - Valve gate type mold assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the heat insulating properties of a material passage on the gate side and anti-gate side of a valve casing. <P>SOLUTION: The gate side and anti-gate side of the valve casing 25 are fitted in the insertion holes 23 and 22 of a fixed mold 1. The material passage 34 is formed in the valve casing 25 and an air heat insulating layer 64 is provided to the periphery of the inlet part 36 of the material passage 34. Further, an air heat insulating layer 62 on the gate side surrounding the material passage 34 is provided in the valve casing 25. By this constitution, the heat insulating properties of the material passage 34 on the gate side and anti-gate side of the valve casing 25 is enhanced. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve gate type mold apparatus used for injection molding of thermoplastic resin.

[0002]

In a hot runner die apparatus for heating a resin, which is a molding material in a material passage to a gate to a product cavity, to constantly keep a molten state,
2. Description of the Related Art A valve gate type mold device is known in which a gate is mechanically opened and closed by a valve pin which is a valve body. The hot runner mold device 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. 4 shows an example of a valve device 101 in this type of valve gate type mold device. In the figure, 102 is a tubular valve casing, and this valve casing 102 is connected to a manifold, and
It is inserted into an assembling hole 104 formed in the fixed-type main body 103. Then, the valve casing 102 is
The large diameter portion 105 of the end portion on the manifold side and the fixing ring 107 fixed to the outer peripheral surface of the end portion on the opposite side of the gate 106 are fitted in the assembling hole 104, so that the main body portion 1
It is supported by 03, and in the other part, the valve casing
A gap forming a heat insulating layer is formed between 102 and the main body 103. The inside of the valve casing 102 is a material passage 108 communicating with the gate 106. And
A valve pin 112 that penetrates the material passage 108 and moves in the vertical direction in the drawing to open and close the gate 106 is provided. Further, the material passage 1 is provided on the outer peripheral surface of the valve casing 102.
A heater 109 for heating the resin in 08 is provided, and a cylindrical heater cover 110 that covers the heater 109 from the outer peripheral side is fixed.

As described above, the resin in the material passage 108 is always kept in a molten state by the heating of the heater 109, but the resin filled from the gate 106 into the product cavity 111 must be cooled in order to solidify. I won't. Moreover, in order to improve the molding efficiency, it is desirable to cool it quickly. Therefore, the valve casing 102 and the fixed-type main body 103 in which the valve casing 102 is incorporated are provided.
Insulation between is important. For this heat insulation, a gap that forms a heat insulating layer is formed between the outer surface of the heater cover 110 that covers the valve casing 102 and the heater 109 and the inner surface of the assembling hole 104 that incorporates the heater cover 110. The outer surface and the inner surface of the built-in hole 104 are in contact with each other only to a small extent.

As described above, the valve casing 102 and the fixed-type main body 103 are brought into contact with each other in a small area to enhance the heating efficiency by the heater 109. 106 large diameter part 1
It tends to be higher in the central part than 05. This is because the large-diameter portion 105 of the valve casing 102 is in contact with the fixed-type main body portion 103, and the valve casing is connected through this contact portion.
This is because heat escapes from 102 to the fixed body 103.

Further, a fixing ring 107 is provided on the valve casing 102 and the fixed type main body 103, and the fixing ring 107 is brought into contact with a small area to improve the heating efficiency by the heater 109 from the valve casing 102 side. Since the transfer of heat due to the heat conduction of the fixing ring 107 is unavoidable, the temperature of the valve casing 102 on the gate 106 side from the intermediate portion of the heater 109 decreases, and the entire material passage 108 cannot be heated uniformly. It was

SUMMARY OF THE INVENTION The present invention is intended to solve such a problem, and an object thereof is to provide a valve gate mold apparatus which is excellent in the heat insulating property of the material passage on the non-gate side of the valve casing. Provided is a valve gate type mold device having excellent heat insulation of a material passage on the side opposite to the gate of a valve casing.

[0008]

In order to achieve the above object, a valve gate type mold apparatus according to a first aspect of the present invention includes a plurality of mold bodies which are opened and closed to form a product cavity between them when the mold is closed. A valve device provided in a mold body having a gate opening to a product cavity among these mold bodies, the valve device being incorporated in an assembly hole formed in the mold body and having a material passage inside thereof. The valve casing has a formed valve casing, a pin body provided inside the valve casing for opening and closing the gate, and heating means provided in the valve casing, and a non-gate side of the valve casing is fitted into the assembling hole. In the valve gate type mold device having the inlet portion of the material passage on the side opposite to the gate of the valve casing, an air heat insulating layer is provided around the inlet portion. Those digits.

At the time of molding, a plurality of mold bodies are closed to form a product cavity between these mold bodies, and a valve body is moved to open the gate, and heat is introduced into the product cavity from the material passage through the gate. Inject a molding material such as a plastic resin. After the molding material is filled in the product cavity, the valve body is moved to close the gate.
Further, after the molding material in the product cavity is solidified, a plurality of mold bodies are opened, and the molded product is released and taken out. After that, 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 casing is always kept in a molten state by the heating of the heater.

The valve casing incorporated in the assembling hole is supported by the mold body by fitting the non-gate side into the assembling hole. In this fitting and supporting structure, the air insulation provided around the inlet of the material passage is provided. The layer can improve heat insulation between the material passage and the outside on the side opposite to the gate.

According to a second aspect of the present invention, in the valve gate mold apparatus according to the first aspect of the present invention, the air heat insulating layer is a groove that is open to the side opposite to the gate.

This makes it possible to easily form the air heat insulating layer.

The invention of claim 3 is the same as claim 1 or 2.
In the valve gate mold apparatus of the invention described above, the gate side of the valve casing is fitted into the assembling hole, and a gate side air heat insulating layer surrounding the material passage is provided inside the valve casing.

The valve casing incorporated in the assembling hole is supported by the mold by fitting the gate side into the assembling hole, and in this fitting and supporting structure, the gate side air heat insulating layer surrounding the gate side material passage allows the gate to be provided. On the side, the heat insulation between the material passage and the outside can be improved.

According to a fourth aspect of the present invention, in the valve gate mold apparatus according to the third aspect of the invention, a nest for inserting the valve body is formed in the valve casing, and a mounting hole for mounting the nest is formed. It is provided in the valve casing, and the gate side air heat insulating layer is provided between the insert and the mounting hole.

By processing the outer periphery of the insert or the mounting hole,
The gate-side material passage can be easily formed by mounting the nest in the mounting hole.

Further, the invention of claim 5 is the valve gate mold apparatus of the invention of claim 4, wherein the gate side air heat insulating layer is formed by a groove formed on the outer periphery of the nest.

By forming a groove on the outer periphery of the insert and closing the groove with the mounting hole, the air insulating layer on the gate side can be easily formed.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a valve gate mold apparatus according to the present invention will be described below with reference to FIGS. First, the configuration of the injection molding die device will be described. Reference numeral 1 is a fixed mold as a first mold body, 2 is a movable mold as a second mold body, and these fixed mold 1 and movable mold 2 are moved in the vertical direction (mold opening / closing direction) in the drawing to open and close each other. , The product cavities 3 having a product shape are formed between them when the mold is closed.

The fixed mold 1 has a fixed side mold plate 6 forming a product cavity 3, a fixed side receiving plate 7 fixed to the back side of the fixed side mold plate 6 (opposite to the movable mold 2), and A fixed side mounting plate (not shown) fixed via a spacer block is provided on the back side of the fixed side receiving plate 7. This fixed-side mounting plate is attached to the fixed-side platen of the injection molding machine. And, in the fixed side mounting plate,
A locate ring and a sprue bush to which a nozzle of a heating cylinder device which is a molding material supply device of an injection molding machine is connected are fixed. The inside of this sprue bush is a sprue which is a material passage. Also,
The sprue bush is provided with a heater that is a heating unit that heats the sprue to constantly keep the thermoplastic resin, which is the molding material, in the sprue in a molten state. In addition, the manifold 8 is provided between the fixed-side receiving plate 7 and the fixed-side mounting plate.
Is provided.

Inside the manifold 8,
A runner 9 which is a material passage for branching the sprue into each product cavity 3 is formed. Further, the manifold 8 is provided with a heater 10 which is a heating means for heating the runner 9 and keeping the thermoplastic resin therein always in a molten state.

A direct gate 20 is formed on the fixed mold 1, and the direct gate 20 is formed on the fixed-side mold plate 6. Further, the fixed mold 1 is incorporated with a valve device 21 which is a gate opening / closing means for opening / closing the direct gate 20.

Next, the structure of the valve device 21 will be described. The fixed side receiving plate 7 constituting the main body of the fixed mold 1 is formed with a built-in hole 22 penetrating in the mold opening / closing direction, and further, inside the fixed side mold plate 6 as the main body, An assembling hole 23 communicating with the assembling hole 22 is formed, and the gate 20 is provided at the tip of the assembling hole 23 so as to communicate with the product cavity 3. Then, a substantially cylindrical valve casing 25 is incorporated in the assembling holes 22 and 23. The valve casing 25 includes a flange portion, which is a large-diameter portion, on the side opposite to the gate 20 of a main body portion 26, which is a small-diameter portion.
27 is integrally formed and is fixed to the manifold 8 and the fixed side receiving plate 7. The outer peripheral surfaces of the main body portion 26 and the flange portion 27 have a cylindrical surface shape. Further, the tip end portion 28 of the valve casing 25 on the gate 20 side has a tapered tapered shape.

Further, a valve pin insertion hole 31 in the mold opening / closing direction is formed through the center of the valve casing 25, and a substantially columnar valve pin 32 is slidably supported in the valve pin through hole 31. Moves in the mold opening / closing direction by driving a driving device (not shown) such as a hydraulic cylinder device to open / close the gate 20. The valve pin 32 has a gate closing portion 33 formed as a straight portion at the tip end thereof, which is removably fitted into the gate 20 to form the gate.
20 is to be closed. The valve pin 32 has the mold opening / closing direction as the axial direction.

A material passage 34 is formed in the valve casing 25 at a position apart from the valve pin 32 and around the valve pin insertion hole 31, and the material passage 34 is formed on the side of the flange portion 27 opposite to the gate. The inlet portion 36 is provided at 35, and the runner 9 is connected to the inlet portion 36. The entrance
The material 36 has a larger cross-sectional area than the other parts of the material passage 34, and an inlet straight portion 37 is formed from the inlet portion 36 toward the gate side. A section 38 is provided. The material passage 34 has a central straight line portion 39 extending from the gate side end of the tapered portion 38 toward the gate side.
The gate side of the central straight portion 39 and the opening end portion 31A of the valve pin insertion hole 31 are connected by the oblique portion 40 of the material passage 34. The slanted portion 40 is slanted with respect to the valve pin insertion hole 31, is located on the same plane including the insertion hole 31, and has a tapered cross-sectional area slightly reduced toward the opening end 31A. ing.

A coil heater 41 which is a heating means for heating the material passage 34 and a substantially cylindrical heater cover 42 which covers the heater 41 from the outside are fitted on the outer peripheral surface of the main body portion 26 of the valve casing 25. There is.

A fixing ring 43 is provided on the outer peripheral surface of the gate-side end of the valve casing 25.
By fitting 43 into the cylindrical fitting hole 23A of the built-in hole 23, the gate side of the valve casing 25 is supported and fixed in a positioned state on the fixed side plate 6 which is a mold, while the flange of the valve casing 25 is provided. A built-in hole fitting portion 44 is provided on the tip side of the portion 27, and the outer peripheral surface of the built-in hole fitting portion 44 is fitted into the large-diameter fitting receiving portion 22A formed in the built-in hole 22 and having a substantially cylindrical shape. is doing. As a result, the gate side of the flange portion 27 of the valve casing 25 is supported and fixed to the fixed side receiving plate 7 which is a mold in a positioned state.

Next, a method of manufacturing the valve casing 25 will be described. The center of the valve casing 25 is formed as a nest 51, and the valve pin insertion hole 31 is formed at the center of the nest 51. As shown in FIGS. 1 and 3, the nest 51 has a cylindrical outer peripheral surface 52. With
A substantially conical tip surface 53 is formed on the gate side. Further, the valve casing 25 is formed with a mounting hole 54 for mounting the insert 51 from the side opposite to the gate, and the mounting hole 54 has a shape corresponding to the outer circumference of the insert 51 and is formed in the inner surface corresponding to the outer peripheral surface 52. It has a peripheral surface 55.

Further, a groove 134 which forms a part of the material passage 34 is formed on the outer periphery of the insert 51, and the groove 134 corresponds to the inlet straight line portion 37 and the central straight line portion 39 and forms an inlet straight line. A part 137 and a central straight line forming part 139.
The cross sections of 7 and 139 have almost the same shape, and are formed in an arcuate groove having a center S at the same depth position from the outer surface. In addition, the mounting hole 54 corresponding to the inlet straight line forming portion 137.
A straight formed portion 137A and a taper formed portion 138 are formed on the inner peripheral surface 55 of the, and the cross section of the inlet straight portion 37 formed by combining the straight formed portions 137 and 137A is circular.

A collar portion 56 is provided around the gate 51 of the insert 51, and a step portion 57 with which the collar portion 56 abuts is formed in the mounting hole 54.

Further, a space is provided between the outer periphery of the valve casing 25 and the assembling holes 22 and 23 on the gate side opposite to the fitting position of the fitting hole 23A and the fixing ring 43. Has been formed. Further, a gap 59 is provided between the tip side of the valve casing 25 and the built-in hole 23, and the gap 59 communicates with the material passage 34 and the gate 20 so that the resin as the molding material enters and the resin heat insulation. A layer is formed.

Further, as a characteristic construction of the present invention, as shown in FIGS. 1 and 3, an outer peripheral surface 52 of the insert 51 on the gate side is formed.
A groove 61 is formed so as to surround the inclined portion 40.
A gate-side air heat insulating layer 62 is formed between 61 and the inner peripheral surface of the mounting hole 54. In the main body portion 26 of the valve casing 25, a hole-shaped communication passage 63 communicating with the gate-side air heat insulation layer 62 is formed, and this communication passage 63 communicates the gate air heat insulation layer 62 with the outside. Therefore, heating the gate side air insulation layer
Even if the air in 62 expands, it can escape to the air insulating layer 58.

Furthermore, an air heat insulating layer 64 is formed in the flange portion 27 by a groove surrounding the inlet straight portion 37.
The air insulating layer 64 has an annular shape centered on the valve pin insertion hole 31, and its depth is approximately one half of the thickness of the flange portion 27.
It is formed below.

Then, the nest 51 inserted into the mounting hole 54.
Are fixed by shrink fitting, or fixed by brazing or diffusion bonding. When fixing with this diffusion bonding,
The diffusion bonding is performed through a contact process between bonding interfaces, a process in which the contact surface is brought into close contact with time, and a process in which the bonding boundary disappears. In the contact process, slip deformation due to pressure, surface coating In the next process, due to rupture and migration, the vacancy diffusion, boundary diffusion, that is, the process in which the adhesion progresses due to the movement of dislocations, and in the next process, the formation of a new crystal structure by recrystallization or crystal growth, and the bonding Is involved in the decomposition or dissolution of coatings and inclusions present in
Almost perfect joining is made. Specifically, in diffusion welding using a solvent, a solvent made of a nickel alloy, such as BNi, is used, and the solvent is heated and melted, and the materials are joined together by capillary action, that is, the outer periphery of the insert 51 and the mounting. Permeate the holes 54. Then, in the diffusion bonding, the material structure is transformed in the bonded portion and firmly bonded, and the material leakage in the material passage 34 can be completely prevented.

Next, the operation of the above configuration will be described. First, the fixed mold 1 and the movable mold 2 are closed, a product cavity 3 is formed between the fixed mold 1 and the movable mold 2, and then the valve pin 32 is moved away from the movable mold 2 to open the gate 20. To do. Then, a molten thermoplastic resin, which is a thermoplastic molding material, is injected into the fixed mold 1 from the injection molding machine. This resin passes through the runner 9 of the manifold 8 and the like, and further passes through the spiral material passage 34 from the inlet portion 36 and the open end portion 31 of the tip end portion of the valve casing 25.
It flows into the product cavity 3 from A and the gate 20. Then, after the molten resin is filled in the product cavity 3 in this manner, the valve pin 32 moves toward the movable mold 2 through the holding pressure and is fitted into the gate 20 to close the gate 20.
Then, after the resin in the product cavity 3 is cooled and solidified, the fixed mold 1 and the movable mold 2 are opened to take out the resin in the product cavity 3, that is, the molded product. Then, the mold is closed again and the above molding cycle is repeated.

The valve casing 25 assembled in the assembling holes 22, 23 is positioned by fitting the large diameter flange portion 27 into the large diameter fitting receiving portion 22A, and the fixing ring 43 is provided on the gate side. Positioning is performed by fitting in the fitting hole 23A. In the valve casing 25 having such a positioning structure, the material passage 34 is provided on the side opposite to the gate.
By providing an air heat insulating layer 64 that surrounds the gate side, and by providing a gate side air heat insulating layer 62 that surrounds the material passage 34 on the gate side,
The heat insulating properties on both sides of the valve casing 25 can be improved. Therefore, the temperature of both sides of the valve casing 25, which is easy to transfer heat due to the fitting structure, can be brought close to the center side, and the entire material passage 34 can be heated uniformly.

As described above, in this embodiment, according to the first aspect, the fixed mold 1 and the movable mold 2, which are a plurality of mold bodies that open and close each other to form the product cavity 3 between them when the mold is closed,
Gate 20 of these molds that opens to product cavity 3
And a valve device 21 provided on the fixed mold 1 as a mold body, which is installed in the assembling holes 22 and 23 formed in the fixed mold 1 as the mold body and has the material passage 34 inside. The valve casing 25 formed in the above, a valve pin 32 that is a pin body provided inside the valve casing 25 to open and close the gate 20, and a heater 41 that is a heating means provided in the valve casing 25.
In the valve gate type mold device in which the non-gate side of 25 is fitted into the built-in hole 22 and the inlet side 36 of the material passage 34 is provided on the side 35 opposite the gate of the valve casing 25, the air insulating layer 64 is provided around the inlet 36. Therefore, at the time of molding, a plurality of fixed dies 1 and movable dies 2 are closed to form a product cavity 3 between these fixed dies 1 and movable dies 2, and the valve pin 32 is moved to open the gate 20. , Material passage 34 to gate 20
A molding material such as a thermoplastic resin is caused to flow into the product cavity 3 via. After the molding material is filled in the product cavity 3, the valve pin 32 is moved to move the gate.
Block 20. Furthermore, after the molding material in the product cavity 3 is solidified, the fixed mold 1 and the movable mold 2 are opened, and the molded product is released and taken out. After that, the mold is closed again and the above molding cycle is repeated. Throughout the entire molding cycle, the molding material in the material passage 34 of the valve casing 25 is constantly kept in a molten state by the heating of the heater 41.

The valve casing 25 incorporated in the assembling holes 22 and 23 is supported by the movable mold 1 by fitting the non-gate side into the assembling hole 22, and in this fitting and supporting structure, the inlet portion of the material passage 34 is provided. The air insulation layer 64 provided around the periphery 36 can improve heat insulation between the material passage 34 and the outside on the side opposite to the gate.

Further, as described above, in this embodiment, the air heat insulating layer 64 is a groove opening to the side surface 35 opposite to the gate, so that the air heat insulating layer 64 can be simply constructed. .

As described above, according to the third embodiment, the gate side of the valve casing 25 is fitted into the assembling hole 23, and the material passage is provided inside the valve casing 25.
Since the gate side air heat insulating layer 62 surrounding the 34 is provided, the valve casing 25 incorporated in the incorporating hole 23 is supported by the fixed mold 1 by fitting the gate side into the incorporating hole 23,
In this fitting support structure, the heat insulation between the material passage 34 and the outside can be improved on the gate side by the gate side air heat insulating layer 62 surrounding the gate side material passage 34.

Further, as described above, in this embodiment, in accordance with the fourth aspect, the valve casing 25 is formed with the insert 51 through which the valve pin 32 as the valve body is inserted.
Since the mounting hole 54 for mounting the 51 is provided in the valve casing 25 and the gate side air heat insulating layer 62 is provided between the nest 51 and the mounting hole 54, the outer periphery of the nest 51 or the mounting hole 54 is processed,
By mounting the nest 51 in the mounting hole 54, the gate-side material passage 62 can be easily formed.

Further, as described above, in this embodiment, since the gate-side air heat insulating layer 62 is formed by the groove 61 formed on the outer periphery of the nest 51 in this embodiment, the groove formed on the outer periphery of the nest 51 is formed. The air insulating layer 62 on the gate side can be easily formed by closing 61 with the mounting hole 54.

Further, as an effect of the embodiment, since the material passage 34 is formed at a position apart from the valve pin 32,
Since the molten resin flows away from the valve pin 32, the flow of the resin does not receive resistance from the valve pin 32, and high-pressure high-speed filling is possible. Further, since the valve pin insertion hole 31 for inserting the valve pin 32 is formed in the valve casing 25 and the material passage 34 is formed around the valve pin through hole 31, the molten resin is formed around the valve pin insertion hole 31. Since the material flows through the material passage 34, the flow of the molten resin can be
No resistance from 32. Further, since the cross-sectional area of the straight line portion 37 is formed larger than the others, the connection with the runner 9 is easy and reliable, and by providing the taper portion 38, the molten resin of the inlet straight line portion 37 is smoothly formed in the central portion 39. Flows into. Moreover, since the cross-sectional area of the obliquely installed portion 40 is tapered slightly toward the opening end 31A, the flow of the molten resin is restricted, and the opening end 31A formed in the mold opening / closing direction further reduces the mold. It flows in the opening / closing direction and is filled into the product cavity 3 through the gate 20.

The present invention is not limited to the above embodiment, and various modifications can be made. For example,
A groove serving as a gate-side heat insulating layer may be formed on the inner surface of the mounting hole.

[0045]

According to the valve gate mold apparatus of the first aspect of the present invention, in the valve gate mold apparatus having the inlet of the material passage on the side opposite to the gate of the valve casing, air insulation is provided around the inlet. Since the layer is provided, the heat insulation between the material passage and the outside can be improved on the side opposite to the gate.

In addition to the effect of claim 1, the invention of claim 2 is a groove in which the air heat insulating layer opens to the side surface opposite to the gate, and the air heat insulating layer can be easily constructed.

The invention of claim 3 is the same as claim 1 or 2.
In addition to the effect of (1), the gate side of the valve casing is fitted into the built-in hole, and a gate side air heat insulating layer that surrounds the material passage is provided inside the valve casing. The heat insulation with the outside can be improved.

Further, in addition to the effect of claim 3, the invention of claim 4 forms a nest through which the valve body is inserted in the valve casing, and provides a mounting hole for mounting the nest in the valve casing. The gate-side air heat insulating layer is provided between the insert and the mounting hole, and the gate-side material passage is formed by processing the outer periphery of the insert or the mounting hole and mounting the insert in the mounting hole. It can be easily formed.

In addition to the effect of claim 4, the invention of claim 5 forms the gate side air heat insulating layer by the groove formed on the outer periphery of the nest, and the groove is formed on the outer periphery of the nest. The gate-side air heat insulating layer can be easily formed by closing the groove with the mounting hole.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a valve gate mold apparatus of the present invention.

FIG. 2 is a plan view of the valve device.

FIG. 3 is a front view of the gate side of the nest of the same.

FIG. 4 is a cross-sectional view of a valve gate type mold device showing a conventional example.

[Explanation of symbols]

1 fixed type 2 movable 3 product cavity 20 gates 21 valve device 22 Built-in hole 23 Built-in hole 25 valve casing 31 Valve pin insertion hole 32 valve pin 34 Material passage 41 band heater (heating means) 51 Nesting 54 mounting hole 61 groove 62 Gate side air insulation layer 64 air insulation layer

Claims (5)

[Claims] 1. A plurality of mold bodies that are opened and closed to form product cavities between them when the molds are closed, and a valve device provided on the mold body having a gate opening to the product cavity among these mold bodies, This valve device includes a valve casing that is incorporated in an assembling hole formed in the mold body and has a material passage formed therein, and a pin body that is provided inside the valve casing and that opens and closes the gate.
A heating means provided in the valve casing,
In a valve gate type mold device in which the opposite gate side of the valve casing is fitted into the built-in hole and the inlet side of the material passage is provided on the side opposite to the gate of the valve casing, an air heat insulating layer is provided around the inlet portion. A valve gate type mold device characterized by being provided. 2. The valve gate mold apparatus according to claim 1, wherein the air heat insulating layer is a groove that opens to the side surface opposite to the gate. 3. The gate side air heat insulating layer surrounding the material passage is provided inside the valve casing by fitting the gate side of the valve casing into the assembling hole. Valve gate type mold device. 4. An insert for inserting the valve body is formed in the valve casing, a mounting hole for mounting the insert is provided in the valve casing, and the gate side air insulation is provided between the insert and the mounting hole. The valve gate mold apparatus according to claim 3, wherein a layer is provided. 5. The valve gate mold apparatus according to claim 4, wherein the air insulating layer on the gate side is formed by a groove formed on the outer periphery of the nest.