JP3240615B2 - Valve gate type mold equipment - Google Patents

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 a thermoplastic resin.

[0002]

A hot runner mold apparatus used for injection molding of a thermoplastic resin heats a resin in a material passage to a gate to a cavity and constantly melts the resin in order to increase molding efficiency. To keep. On the other hand, the resin in the cavity to be a product must be cooled and solidified. Therefore, in the hot runner mold device, it is necessary to open and close the gate by some means. As a gate opening / closing method, there is a valve gate method in which a gate is mechanically opened / closed by a valve pin.

Here, an example of a conventional valve gate type mold apparatus will be described with reference to FIG. Reference numeral 1 denotes a fixed mold, and 2 denotes a movable mold. The fixed mold 1 and the movable mold 2 which are molds move in the vertical direction in the drawing (the mold opening / closing direction) to open and close, and when the mold is closed, a product shape is formed therebetween. The cavity 3 is formed. The fixed mold 1 includes a fixed mold plate 6 and the fixed mold plate 6.
, A fixed-side receiving plate 7 fixed to the surface opposite to the movable mold 2. A gate bush 9 is fitted into a gate bush mounting hole 8 formed through the fixed-side mold plate 6. This gate bush 9
Has a gate 10 that opens to the cavity 3 at the lower end in the figure.

[0004] A valve casing 14 of a valve device 13 is mounted in a mounting hole 11 formed through the fixed receiving plate 7 and a mounting hole 12 formed inside the gate bush 9. This valve casing 14
Is substantially cylindrical, and has a material passage 15 inside communicating with the gate 10. On the outer peripheral surface of the valve casing 14, there is provided a band heater 16 as a heating means for always keeping a thermoplastic resin as a molding material in a material passage in a molten state, and a cylindrical shape for covering the band heater 16 from outside. And the heater cover 17 are fitted. Further, an outer cylinder 18 is fitted on the outer peripheral side of the heater cover 17. For heat insulation, a gap 19 is formed between the outer surfaces of the valve casing 14, the heater cover 17 and the outer cylinder 18 and the inner surfaces of the mounting holes 11, 12, but for supporting the valve casing 14, At the end of the gate bush 9 opposite the gate 10, the outer peripheral surface of the outer cylinder 18
Are fitted on the inner peripheral surface. Gate farther than this mating surface 20
On the 10 side, the gap 19 forms an air heat insulating layer, but on the gate 10 side of the fitting surface 20, the gap 19 communicates with the gate 10, so that the resin as a molding material enters the gap 19. .

The valve casing 14 is driven by a hydraulic cylinder or the like (not shown) to move in the mold opening / closing direction of the fixed mold 1 and the movable mold 2 and to move the gate.
A valve pin 21 for opening and closing the valve 10 is provided. The valve pin 21 fits into the gate 10 to close it. In order to support the valve pin 21 on the gate 10 side, a support piece 22 is screwed into the inner peripheral side of the tip of the valve casing 14 on the gate 10 side, and formed on the inner peripheral side of the support piece 22. The valve pin 21 is slidably fitted inside the plurality of support pieces 23 thus formed.

Reference numeral 24 denotes a temperature sensor provided along the heater 16. Reference numeral 26 denotes a movable mold plate of the movable mold 2.

When the valve pin 21 operates smoothly, the gate
In order to reliably open and close the valve 10, the valve pin 21 and the gate 10 need to be securely aligned. Also,
If the valve pin 21 and the gate 10 are eccentric, the flow of the resin flowing into the cavity 3 from the inside of the valve casing 14 through the gate 10 may be deflected, which may cause a molding failure. In order to secure the alignment, it is necessary that the gate bush 9 and the valve casing 14 are securely aligned, and that the valve casing 14 and the valve pin 21 are securely aligned. In the mold apparatus shown in FIG.
Anti-gate in the gate bush 9 to support the
At the end on the side of the 10, the outer peripheral surface of the outer cylinder 18 is fitted to the inner peripheral surface of the built-in hole 12. . On the other hand, if the mating surface 20 is located near the cavity 3,
This is disadvantageous in terms of heat insulation between the cavity 3 side and the valve casing 14 side. Therefore, in the mold apparatus shown in FIG.
However, the positioning accuracy is degraded. Also, since the abutting portion between the tip of the heater cover 17 and the outer peripheral surface of the valve casing 14 faces the gap 19 in which the resin enters, the resin is not covered by the heater cover 17 but the resin is And the heater 16 is deteriorated. In addition,
When the heater 16 has deteriorated, the heater 16 can be replaced by removing the heater 16 and the heater cover 17 from the valve casing 14 toward the distal end side.

FIGS. 3 and 4 show another conventional valve gate type mold apparatus which is an improvement of the mold apparatus shown in FIG. Parts corresponding to those of the mold apparatus shown in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 3, reference numeral 31 denotes a manifold.
A runner 32 communicating with the material passage 15 of the valve casing 14 is provided inside, and a heater (not shown) for always keeping the resin in the runner 32 in a molten state is provided. The end of the valve casing 14 on the side opposite to the gate 10 is fixed to the manifold 31. A guide bush 33 for supporting the valve pin 21 is provided at an end of the valve casing 14 on the side opposite to the gate 10.
Has been fixed. The valve pin 21 slidably passes through the inside of the guide bush 33.

The mold apparatus shown in FIGS. 3 and 4
The gate 10 is not formed on the fixed side template 6 without the gate bush 9. Also, the valve casing 14
These are also directly incorporated into the installation holes 36 formed in the fixed side mold plate 6. Providing the gate bush 9 has an advantage that, for example, when the wear of the gate 10 progresses, it can be dealt with by replacing the gate bush 9 only. However, if the gate bush 9 is not provided, the cost can be reduced by reducing the number of parts. There are advantages such as.

Further, a separate support piece 22 is not provided at the tip of the valve casing 14, and a valve pin support hole 37 through which the valve pin 21 is slidably penetrated is directly provided at the tip of the valve casing 14 on the gate 10 side. Has formed. The valve pin 21 is always fitted in the valve pin support hole 37 for centering the valve pin 21, but in order to secure a resin flow path, as shown in FIG. Are formed with a plurality of concave grooves 38 penetrating in the axial direction. Further, the outer cylinder 18 that covers the heater cover 17 is also eliminated.

Further, a heat insulating ring 41 is fixed to the outer peripheral surface of the distal end portion of the valve casing 14 at a position closer to the gate 10 than the heater 16 and the heater cover 17 by shrink fitting. Note that shrink fitting means fitting the heat insulating ring 41 to the valve casing 14 in a state where the ring is heated and expanded. After that, when the heat insulating ring 41 cools and contracts,
The heat insulating ring 41 is firmly fastened to the valve casing 14. After that, since the heat insulating ring 41 and the valve casing 14 cannot be individually heated or cooled, the heat insulating ring 41 is
Can not be removed from. In order to support the distal end of the valve casing 14, the outer peripheral surface of the heat insulating ring 41 is fitted to the inner surface of the mounting hole 36 of the fixed mold plate 6. This mating surface 42 is used for the heater 16 and the heater cover.
It is located closer to the gate 10 than 17. Note that a concave groove 43 is formed on the inner peripheral surface of the heat insulating ring 41 in order to enhance heat insulation.

In the conventional mold apparatus, the outer diameter of the outer peripheral surface of the valve casing 14 at the position where the heater 16 and the heater cover 17 are fitted and the heat insulating ring 41
The outer diameter of the heat-insulating ring 41 is larger than the inner diameters of the heater 16 and the heater cover 17, although there is a slight step difference from the outer diameter at the position where is fitted.

In the mold apparatus shown in FIGS. 3 and 4, a heat insulating ring which is located closer to the gate 10 than the heater 16 and the heater cover 17 and is fixed to the outer peripheral surface of the valve casing 14 is provided.
Since the valve casing 14 is supported on the fixed-side template 6 by 41, the accuracy of alignment between the gate 10 of the fixed-side template 6 and the valve casing 14 can be further improved. Further, it is possible to suppress the resin as the molding material from entering the heater 16.

However, as described above, the heat insulating ring 41 fixed to the valve casing 14 by shrink fitting cannot be removed from the valve casing 14, and the heat insulating ring 41
Is larger than the inner diameters of the heater 16 and the heater cover 17, the heat insulating ring 41 hinders the heater 16 from being removed from the valve casing 14. Therefore, it is impossible to replace only the heater 16. When the heater 16 is deteriorated, the entire valve device 13 including the valve casing 14 must be replaced.

In a mold apparatus using a heat insulating ring 41 as shown in FIG. 3, it is difficult to combine the mold apparatus with the gate bush 9. That is, as shown by a chain line in FIG.
The incorporation of the gate bush 9 having a shape similar to that shown in FIG.
It is not possible because of interference. In order to prevent the heat insulating ring 41 from interfering, the gate bush 9 needs to be thinner at a portion where the heat insulating ring 41 is fitted, but this has a problem in strength and the like. In order to secure the thickness of the gate bush 9, it is conceivable to increase the angle α of the tapered portion of the gate bush 9 on the gate 10 side. However, on the contrary, the fixed side template 6 becomes thinner. There is a problem that there is a problem that the diameter is too large or the diameter of the entire gate bush 9 becomes too large.

The present invention is intended to solve such a problem. In a valve gate type mold apparatus using a heat insulating ring for supporting a valve casing, a heater mounted on an outer peripheral side of a valve casing is provided. The purpose is to enable exchange. Another object of the present invention is to make it possible to incorporate a gate bush.

[0017]

According to a first aspect of the present invention, there is provided a valve gate type mold apparatus comprising: a plurality of molds which are opened and closed with each other and form a cavity therebetween when the mold is closed; A valve device provided in a mold having a gate that opens to a cavity among these molds, and the valve device is incorporated in an assembling hole formed in a main body of the mold and has a material passage. A substantially cylindrical valve casing formed therein, and a heater detachably fitted to the outer peripheral surface of the valve casing,
A valve pin provided inside the valve casing to open and close the gate; and a heat insulating ring fixed to an outer peripheral surface of a gate-side tip portion of the valve casing and fitted to an inner surface of the mounting hole, the outer periphery of the valve casing. surfaces, and heaters mating surface consisting of a cylindrical surface, a first step surface that is bent to the inner peripheral side from the gate side end of the heater <br/> fitting surface, of the first step surface An intermediate cylindrical surface bent from the periphery to the gate side, a planar second step surface bent inward from the gate side end of the intermediate cylindrical surface, and an inner peripheral edge of the second step surface. A gate-side cylindrical surface bent perpendicularly to the gate side, a third step surface bent inward from the gate-side end of the gate-side cylindrical surface, and the gate side from the inner peripheral edge of the third step surface. With a tapered surface that is bent The heat insulating ring is fixed to a step portion formed by the second step surface and the gate-side cylindrical surface, and the entire heat insulating ring is located on the inner peripheral side of the heater fitting surface in the valve casing. is there.

In molding, after closing a plurality of molds, the valve pin is moved to open the gate. In this state, the molding material is injected from the molding machine. This molding material is filled into the cavity from the gate through a material passage in the valve casing. Thereafter, the valve pin moves and engages the gate, and the gate is closed. Further, after the molding material in the cavity, that is, the product is solidified, the mold is opened to take out the molded product. During that time, 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 gate-side tip of the valve casing is supported by a heat-insulating ring fixed to the outer peripheral surface of the valve casing fitted into the inner surface of the mounting hole of the mold body. Is located closer to the gate than the heater fitting surface on the outer peripheral surface of the valve casing and is fixed to the stepped portion recessed toward the inner peripheral side, so the fitting surface between the heat insulating ring and the mounting hole is closer to the gate. Will be located. As a result, the alignment between the gate and the valve casing becomes more reliable. Also, since the entire heat insulating ring is located on the inner peripheral side of the heater fitting surface in the valve casing, the heat insulating ring does not become an obstacle, and the heater is pulled out toward the gate-side tip of the valve casing. It can be removed from this valve casing. That is, when the heater is deteriorated, it is possible to replace only the heater.

According to a second aspect of the present invention, in the valve gate type mold apparatus according to the first aspect of the present invention, the main body of the mold has a mold plate, and the gate is removably assembled in the mold plate. A gate bush, the gate bush forming a gate-side portion of the mounting hole, and the heat insulating ring is fitted to the inner surface of the mounting hole by the gate bush.

As described above, the heat insulating ring is fixed to the stepped portion which is located closer to the gate than the heater fitting surface on the outer peripheral surface of the valve casing and is depressed toward the inner peripheral side.
The main body of the mold can be configured such that the gate bush is embedded in the mold plate without the heat insulating ring becoming an obstacle. That is, it is not necessary to make the corresponding portion of the gate bush thin in order to receive the heat insulating ring. When the gate is formed on the gate bush in this way, when the wear of the gate portion has progressed, it can be dealt with by replacing only the gate bush.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a valve gate type mold apparatus according to the present invention will be described below with reference to FIG. 51 is a fixed mold, 52 is a movable mold, and the fixed mold 51 and the movable mold 52, which are molds, move in the vertical direction in the figure (mold opening and closing direction) to open and close, and when the mold is closed, a product shape is formed therebetween. The cavity 53 is formed. The fixed mold 51 includes a fixed mold plate 56 and an upper surface of the fixed mold plate 56 shown in the drawing, that is, a movable mold 52.
And a fixed-side receiving plate 57 fixed to the opposite surface. Although not shown, the fixed mold 51 has a manifold similarly to the mold apparatus shown in FIG.

A gate bush 61 that forms the main body of the fixed mold 51 together with the fixed mold plate 56 and the fixed receiving plate 57 is detachable in a gate bush mounting hole 58 formed through the fixed mold plate 56. Is fitted. The gate bush 61 has a tapered portion 62 in which the lower side in the drawing, that is, the cavity 53 side is tapered toward the cavity 53 side, and a gate 63 opening to the cavity 53 is formed at the tip of the tapered portion 62. I have. A cooling water passage 64 is formed between the inner surface of the gate bush mounting hole 58 and the gate bush 61, and an O-ring 65 for preventing water leakage is mounted on the cooling water passage 64. .

A valve device 71 for opening and closing the gate 63 is incorporated in the fixed mold 51. Next, the configuration of the valve device 71 will be described. The fixed side receiving plate 57 is formed with a mounting hole 72 penetrating in the mold opening and closing direction, and the inside of the gate bush 61 is a mounting hole 73 communicating with the mounting hole 72. A substantially cylindrical valve casing 76 is incorporated in the installation holes 72 and 73. Although not shown, one end of the valve casing 76 has a flange shape and is fixed to the manifold and the fixed-side receiving plate 57 similarly to the mold apparatus shown in FIG. Also, the valve casing 76
Is a material passage 77 for connecting a runner, which is a material passage in the manifold, to the gate 63. The lower end in the drawing of the material passage 77, that is, the end on the gate 63 side is a valve support hole 78 having a smaller diameter than the other parts of the material passage 77. A plurality of concave grooves 79 are formed in the inner surface of the valve support hole 78 so as to penetrate in the mold opening / closing direction.
The valve support hole 78 is coaxially opposed to the gate 63.
In the valve casing 76, a valve pin 80 as a valve body that moves in the mold opening / closing direction by driving a hydraulic cylinder (not shown) or the like is incorporated. The valve pin 80 is always slidably fitted in the valve support hole 78, and is fitted in the gate 63 so as to be able to be inserted and removed so as to close the gate 63.

The outer peripheral surface of the valve casing 76 is provided with heaters fitting surface 81 consisting of a cylindrical surface, the heaters fitting surface 81
A first stepped surface 82 bent from the lower end of the drawing, that is, the end of the gate 63 side to the inner peripheral side, an intermediate cylindrical surface 83 bent from the inner peripheral edge of the first stepped surface 82 to the gate 63 side, and an intermediate cylindrical surface 83
A flat second step surface 84 bent inward from the gate 63 side end, a gate-side cylindrical surface 85 bent perpendicularly to the gate 63 from the inner periphery of the second step surface 84, A third step surface 86 bent inward from the end of the gate-side cylindrical surface 85 on the gate 63 side, and a tapered surface 87 bent from the inner periphery of the third step surface 86 toward the gate 63 are provided. And this tapered surface
The valve support hole 78 and the concave groove 79 are opened at 87.

A band heater 91 for heating the material passage 77 is provided on the heater fitting surface 81 of the valve casing 76.
A substantially cylindrical heater cover 92 that covers the heater 91 from the outside is detachably fitted. Note that 93
Is a temperature sensor provided along the heater 91.

A short cylindrical heat insulating ring 96 is fitted and fixed to the step formed by the second step surface 84 and the gate-side cylindrical surface 85. This fixation is due to shrink fitting. The outer peripheral surface of the heat insulating ring 96 is located on substantially the same cylindrical surface as the intermediate cylindrical surface 83 of the valve casing 76, and the end surface of the heat insulating ring 96 on the gate 63 side is substantially flush with the third step surface 86 of the valve casing 76. They are located on the same plane. Therefore, the entire heat insulating ring 96 is located on the inner peripheral side of the heater fitting surface 81 in the valve casing 76. Note that a concave groove 97 that forms an air heat insulating layer is formed on the inner peripheral surface of the heat insulating ring 96.

Further, the outer peripheral surface of the heat insulating ring 96 is fitted to a cylindrical fitting surface 98 of the same diameter formed in the mounting hole 73 of the gate bush 61. As a result, the valve casing 76 is supported by the gate bush 61 that forms the main body of the fixed die 51 at the end on the gate 63 side. A gap 99 is formed between the inner surfaces of the mounting holes 72 and 73 and the outer surface of the valve casing 76 or the heater cover 92 for heat insulation except at the fitting surface 98 between the heat insulating ring 96 and the gate bush 61. Have been. Insulation ring 96
Cuts off the portion of the gap 99 on the gate 63 side and the portion on the heater 91 side.

Reference numeral 101 denotes a movable mold plate of the movable mold 51. Next, the operation of the above configuration will be described.
In molding, first, the fixed mold 51 and the movable mold 52 are closed, a cavity 53 is formed between the fixed mold 51 and the movable mold 52, and then the valve pin 80 is moved away from the movable mold 52 to form a gate. Release 63. Note that, even when the gate 63 is open, the valve pin 80 remains in the valve casing 76.
Remains in the valve pin support hole 37 of FIG. And
A thermoplastic resin as a molding material is injected into the fixed mold 51 from an injection molding machine. This resin is filled into the cavity 53 from the gate 63 through a material passage 77 in the valve casing 76 and a concave groove 79 around the valve pin support hole 78 through a runner of the manifold. Thereafter, after the pressure is held, the valve pin 80 moves toward the movable mold 52, and the gate 63 moves.
And the gate 63 is closed. The resin in the cavity 53 is actively cooled by cooling water passing through the cooling water passage 64. After the resin in the cavity 53, that is, the product is cooled and solidified, the fixed mold 51 and the movable mold 52 are opened, and the molded product is taken out. Thereafter, the mold is closed again, the above steps are repeated, and the molding is repeated.
During that time, the resin in the material passage 77 of the valve casing 76 is always kept in a molten state by the heating of the heater 91.

According to the structure of the above embodiment, the heat insulating ring 96
However, on the outer peripheral surface of the valve casing 76, the second concaved inwardly located closer to the gate 63 than the heater fitting surface 81 is located.
Of the heat insulating ring 92 and the mounting hole 73 of the gate bushing 61 are located closer to the gate 63. . Accordingly, the alignment between the gate 63 and the valve casing 76 is more reliable and higher in accuracy, and the alignment between the valve pin 80 and the gate 63 and the valve casing 76 is more reliable and higher in accuracy. Accordingly, it is possible to prevent the flow of the resin flowing from the inside of the valve casing 76 into the cavity 53 through the gate 63 from being deflected, and the moldability is stabilized. Further, the operation of the valve pin 21 is also reliable and stable, and the gate 63 can be opened and closed reliably.

Further, since the entire heat insulating ring 93 is located on the inner peripheral side of the heater fitting surface 81 in the valve casing 76, the heat insulating ring 96 does not become an obstacle,
Heater 91 and heater cover 92 to valve casing
It can be removed from the valve casing 76 by pulling it toward the end of the gate 63 on the gate 63 side. That is, when the heater 91 is deteriorated, only the heater 91 can be replaced.

At the same time, the heat insulating ring 96 is fixed to the stepped portion which is located on the outer peripheral surface of the valve casing 76 on the gate 63 side with respect to the heater fitting surface 81 and is depressed toward the inner peripheral side. Thus, the gate bush 61 can be embedded in the fixed mold plate 56 as in the present embodiment, without causing any obstacle. That is, the insulating ring 96
Therefore, it is not necessary to reduce the thickness of the corresponding portion of the gate bush 61, and a sufficient thickness can be secured at each portion of the gate bush 61. Also, the gate bush 61
It is not necessary to increase the angle of the tapered portion 62, and the thickness of the fixed side mold plate 56 can be sufficiently secured even in the gate bushing hole 58, and the diameter of the entire gate bush 61 needs to be excessively large. Absent. By forming the gate 63 on the gate bush 61 in this way, when the wear of the gate 63 portion has progressed, it is possible to cope by replacing the gate bush 61 alone.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made. For example,
In the above embodiment, the gate 63 is formed on the gate bush 61. However, the present invention can be applied to a mold apparatus in which the gate is directly formed on the fixed mold plate without providing such a gate bush.

[0034]

According to the first aspect of the present invention, a plurality of molds that open and close to each other and form a cavity therebetween when the mold is closed,
A valve device provided in a mold having a gate that opens to a cavity among these molds, and the valve device is incorporated in an assembling hole formed in a main body of the mold and has a material passage. A substantially cylindrical valve casing formed therein, a heater removably fitted to the outer peripheral surface of the valve casing, a valve pin provided inside the valve casing to open and close the gate, and a gate of the valve casing and a thermal insulating ring fixed to the outer peripheral surface side tip fitted to the inner surface of the built-in hole, the outer peripheral surface of the valve casing, the heaters mating surface consisting of a cylindrical surface, said the heater fitting surface A first stepped surface bent inward from the gate side end,
An intermediate cylindrical surface bent from the inner peripheral edge of the first step surface to the gate side, a planar second step surface bent from the gate side end of the intermediate cylindrical surface to the inner circumferential side, A gate-side cylindrical surface bent perpendicularly from the inner peripheral edge of the step surface to the gate side, a third step surface bent from the gate-side end of the gate-side cylindrical surface to the inner peripheral side, and the third step A tapered surface bent from the inner peripheral edge of the surface toward the gate, and fixing the heat-insulating ring to a step formed by the second step surface and the gate-side cylindrical surface. Since the valve casing is located on the inner peripheral side with respect to the heater fitting surface, the fitting surface between the heat insulating ring and the mounting hole is located closer to the gate. The accuracy of alignment can be improved . Also, the heater can be pulled out toward the gate-side tip of the valve casing and removed from the valve casing without the insulation ring becoming an obstacle. It becomes possible to do.

Further, the main body of the mold can be configured such that the gate bush is embedded in the mold plate without the heat insulating ring becoming an obstacle.
If the gate is formed on the gate bush as described above, when the wear of the gate portion progresses, it can be dealt with by replacing only the gate bush.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a valve gate type mold apparatus of the present invention.

FIG. 2 is a sectional view showing an example of a conventional valve gate type mold apparatus.

FIG. 3 is a longitudinal sectional view showing another example of a conventional valve gate type mold device.

FIG. 4 is a cross-sectional view of a distal end portion of the valve casing.

[Explanation of symbols]

 51 Fixed mold (mold) 52 Movable mold (mold) 53 Cavity 56 Fixed mold plate (Main body, Mold plate) 57 Fixed mold plate (Main body) 61 Gate bush 63 Gate 71 Valve device 72 Assembly hole 73 Assembly Hole 76 Valve casing 77 Material passage 80 Valve pin 81 Heater fitting surface 82 First stepped surface 83 Intermediate cylindrical surface 84 Second stepped surface (stepped portion) 85 Gate-side cylindrical surface (stepped portion) 86 Third stepped surface 87 Tapered surface 91 Band heater (heater) 96 Insulation ring

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Chiba 3-1, Koganecho, Niigata City, Niigata Pref. Niigata Works, Mitsubishi Materials Corporation (56) References JP-A-8-90598 (JP, A) JP-A Heisei 4-187415 (JP, A) JP-A-6-23804 (JP, A) JP-A-9-19946 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/26 -45/44 B29C 45/73

Claims (2)

(57) [Claims] A plurality of molds which open and close with each other and form a cavity therebetween when the mold is closed; and a valve device provided in a mold having a gate which opens to the cavity among these molds. The valve device is mounted in a mounting hole formed in the main body of the mold body, and has a substantially cylindrical valve casing having a material passage formed therein, and is detachably fitted to an outer peripheral surface of the valve casing. A valve pin provided inside the valve casing to open and close the gate; and a heat insulating ring fixed to an outer peripheral surface of a gate-side tip portion of the valve casing and fitted to an inner surface of the mounting hole, the valve comprising: the outer peripheral surface of the casing, the heaters mating surface consisting of a cylindrical surface, a first stage which is bent to the inner peripheral side from the gate side end of the heater fitting surface A stepped surface, an intermediate cylindrical surface bent from the inner peripheral edge of the first stepped surface to the gate side, and a planar second stepped surface bent from the gate side end of the intermediate cylindrical surface to the inner side. A gate-side cylindrical surface vertically bent from the inner peripheral edge of the second step surface to the gate side, a third step surface bent from the gate-side end of the gate-side cylindrical surface to the inner circumferential side, A tapered surface bent from the inner peripheral edge of the third step surface to the gate side, and the heat insulating ring is fixed to a step portion formed by the second step surface and the gate-side cylindrical surface; A valve gate type mold apparatus, wherein the entire heat insulating ring is located on the inner peripheral side of the heater fitting surface in the valve casing. 2. The main body of the mold body includes a mold plate, and a gate bush having the gate detachably assembled in the mold plate, and a gate-side portion of the mounting hole is formed by the gate bush. 2. The valve gate type mold apparatus according to claim 1, wherein the heat insulating ring is fitted to an inner surface of the mounting hole with the gate bush.