JPH11170308A - Valve gate device of injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the valve gate of an injection molding machine capable of suppressing the molding inferiority by a solidified layer. SOLUTION: The valve gate apparatus 1 of an injection molding machine consists of a nozzle 6 for ejecting a molten resin, a heater 7 for heating the molten resin in the nozzle 6, the center core pin 2 inserted into the center of the nozzle 6 in order to bore a hole in a molded product and forming an ejection part between the outer peripheral surface of the core pin and the tip of the nozzle 6, the ring gate 3 sliding along the outer peripheral surface of the core pin and stopping the flow of the resin in such a state that the outer peripheral surface of the tip part thereof holds an extremely small gap along with the tip of the nozzle 6 when the tip part is positioned at the part of the ejection port and the cylinder 5 and the piston 4 raising and lowering the ring gate 3 to control the ejection of the molten resin and ejects the molten resin from the ejection port. In the valve gate apparatus 1, a solidified layer peel preventing groove part 10 is provided in the area from the vicinity of the ejection port to the retreat position of the ring gate 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot runner type valve gate device of an injection molding machine for a perforated molded product.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 3-48 discloses a technique for reducing the damage of a mold and a nozzle for mass production of injection molded articles.
No. 851 proposes a [needle opening type nozzle for an injection mold]. However, with this technique, it is not possible to manufacture a hole-formed product (a product having holes formed at the same time as forming).

[0003] In order to manufacture a perforated molded product, the following method can be considered. FIGS. 13A to 13C are schematic diagrams of a conventional pin gate forming method. 1A, a molded article 103 having a large hole 102 can be manufactured by injecting a resin from a pin gate 101 into a cavity. In (b), a weld 104 is formed at a location where the resin into which the pin gate 101 has been introduced is separated into right and left and collides and joins, and the weld 104 is likely to become a defect. In (c), the side closer to the pin gate 101 is likely to be thicker T1, and the side farther away is likely to be thinner T2. Therefore, the pin gate molding method has a problem of weld and uneven thickness.

FIGS. 14A and 14B are schematic views of a conventional ring gate forming method. In (a), since the resin is injected into the cavity via the runner section 111 and the ring gate 112, uniform injection becomes possible. But (b)
When the runner part 111 is removed,
However, the appearance is poor, and a step of removing the burr 113 is required.

FIGS. 15A and 15B are schematic views of a conventional disk gate forming method. In (a), since the resin is injected into the cavity through the runner section 121 and the drain 122, uniform injection becomes possible. However, in (b), when the runner portion 121 is removed, the burrs 123 remain and the appearance is poor, so that a step of removing the burrs 123 is required. That is, both the ring gate forming method and the disk gate forming method have a problem of burr.

Therefore, as a technique for solving the problems of welds and burrs, Japanese Patent Publication No. Sho 60-23972 [Valve Assembly] has been proposed. This technology is for making a disk with a hole in the center, opening the sleeve valve so that it can move up and down along the shaft at the part corresponding to the center hole of the disk, and sending resin through the hole in the shaft. The disk is molded and then closed by lowering the sleeve valve downward to cut and trim the hole in the center of the disk. Here, a structure is adopted in which the shaft portion is always kept warm by a heater so that the sealed resin does not solidify.

[0007]

However, in this device, since the sleeve valve is pressed against the dispersing head located below the sleeve valve, one or both of the contact parts are damaged, and the life is shortened. In addition, if the cut surface is thick, there is a possibility that cutting cannot be performed, and if the cutting force is increased, the life of the component parts is shortened. Furthermore, to heat the shaft,
The shaft increases in diameter. As a result, the outer diameter of the shaft changes, while a force is applied toward the center axis of the sleeve valve due to the mold temperature of the outside of the sleeve valve being low. That is, the expansion force is applied to the sleeve valve from the center and the contraction force is applied from the outside, so that the slide of the sleeve valve becomes unstable, and the slide becomes extremely impossible.

As described above, in the [valve assembly] of Japanese Patent Publication No. 60-23972, the life of the valve is shortened due to the valve abutting on the head, and the smooth movement of the sleeve valve is facilitated by the arrangement of the heater. There is a problem that it is difficult to maintain. Therefore, the applicant has proposed an injection molding machine for forming a perforated molded product in a previous application (Japanese Patent Application No. Hei 8-167789). This injection molding machine is shown in an enlarged manner in FIGS. 16 and 17, in which a center core pin 130 and a ring gate 133 are vertically slidably provided in a nozzle 132 for injecting a resin. Injection and stop of the resin are controlled by the vertical movement of 133. As a movable mold, a movable core pin 131 is provided so as to be connected to the center core pin 130, and a resin is flown from a nozzle 132 into a cavity 134 to form a molded product. The connection of the movable core pin 131 forms a hole in the molded product. FIG. 16 shows a state in which the nozzle is opened, and FIG. 17 shows a state in which the nozzle is closed by a ring gate.

In this device example, the periphery of the upper mold is heated by a heater (not shown) to maintain the molten state of the resin. However, the center core pin cannot be provided with a heater because of its small size. 130, the temperature tends to be lower with respect to the surroundings, and therefore, the portion where the center core pin 130 comes into contact with the molten resin 135,
In some cases, the solidified layer 136 formed by cooling and solidifying the resin is thinly formed in a skin shape. This solidified layer 136 is formed as shown in FIG.
As shown in FIG. 17, when the ring gate 133 is lowered in order to perform injection molding next, the ring gate 133 scrapes off the solidified layer 136, and the shavings 136A thus scraped off as shown in FIG. Cavity 134
In some cases, the resin may penetrate into the molded product and cause molding defects such as burnt or adhered foreign matter to the molded product.

[0010] The present invention focuses on the above problems,
The present invention has been devised to solve this problem effectively, and an object of the invention is to provide a valve gate device of an injection molding machine that can suppress molding failure of a molded product due to a solidified layer.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a nozzle for injecting a molten resin,
A heater for heating the molten resin in the nozzle, and a center core pin inserted into the center of the nozzle for forming a hole in the molded product and forming an injection port between the outer peripheral surface and the tip of the nozzle And slides along the outer peripheral surface of the center core pin, and when the distal end is located at the injection port, the outer peripheral surface of the distal end keeps a very small gap from the distal end of the nozzle to stop the flow of resin. A ring gate,
In the valve gate device of an injection molding machine configured to raise and lower this ring gate to control the injection of the molten resin by controlling the injection of the molten resin, and to inject the molten resin from the injection port, the outer peripheral surface of the center core pin, A groove for preventing solidified layer peeling is provided between the vicinity of the injection port and the retreat position of the ring gate.

Thus, even if a solidified layer of resin is formed on the exposed portion of the center core pin, the exposed portion is reduced in diameter into a concave shape and is configured as a groove for preventing solidified layer from peeling off. A skin-like solidified layer will be formed at a position deep from the moving surface, so that even if the ring gate is slid for injection molding, the solidified layer will not be scraped off and molding defects will occur. Can be prevented beforehand. Also, by arranging a heater on the outer periphery of the nozzle, the nozzle is heated by the heater on the outer periphery and the ring gate is housed in this nozzle, so that the inner diameter of the nozzle is always larger than the outer diameter of the ring gate. Thermally expands. On the other hand, since there is a center core pin at a temperature slightly lower than the temperature held by the ring gate inside the ring gate, there will be a minute gap between the center core pin and the ring gate, and Since the outer periphery is made only of the resin in a molten state, a smooth elevating operation of the ring gate can be ensured. Further, by providing a heater on the outer periphery of the nozzle, it is possible to prevent the resin flowing in the nozzle from being solidified, and to maintain this molten state.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a valve gate device for an injection molding machine according to the present invention will be described below in detail with reference to the accompanying drawings. 1 is an overall sectional view of a valve gate device according to the present invention, FIG. 2 is an enlarged view of a main part of the device shown in FIG. 1, and FIG.
4 is an enlarged view of a portion shown in FIG. 4, and FIG. 4 is a diagram showing a state when the ring gate is lowered in the portion shown in FIG. The point of the illustrated embodiment is that the inventor has provided a groove for preventing the solidified layer from peeling off on the center core pin of the apparatus disclosed in the earlier application (Japanese Patent Application No. 8-167789).

In FIG. 1, a valve gate device 1 is incorporated in an upper die B opposed to a lower die A, and includes a center core bin 2, a ring gate 3 surrounding the center core pin 2, and a ring gate 3. Pistons 4, 4 and a cylinder 5 for raising and lowering the gate 3, a nozzle 6 surrounding the ring gate 3, a heater 7 arranged on the outer periphery of the nozzle 6, a manifold 8, a resin passage 9, the center core pin 2 And a groove 10 for preventing the solidified layer from peeling, which is a feature of the present invention, provided at the front end of the substrate.

The lower mold A is a movable mold and has a convex portion 11 on the upper surface.
And a small concave portion 12 above the convex portion 11. The shape of the lower mold A is appropriately changed depending on the shape of the molded product. The upper mold B is a fixed mold, and the mold 1
4, the intermediate plate 15 and the mounting plate 16 are stacked,
More specifically, the cavity recess 17 is formed in the center of the lower surface of the template 14.
Is formed, the nozzle 6 is fitted from above, and the manifold 8 is overlapped on the nozzle 6.

Further, the ring gate 3 is mounted on the intermediate plate 15 via the cylinder 5 and the pistons 4, 4, and the center core pin 2 is hung on the mounting plate 16 by the stop ring 21, the clamping washers 22, 23 and the nut 24. The intermediate plate 15 and the mounting plate 16 are sequentially stacked on the template 14. At this time, as shown, the ring gate 3 is guided by the guide bush 6a at the base of the nozzle 6. In the figure, reference numeral 25 denotes a manifold heater.

FIG. 2 is an enlarged view of a main part of the valve gate device according to the present invention, and explains the shape characteristics of the ring gate 3 and the mold provided on the center core pin 2 and the lower mold B. The outer circumference of the ring gate 3 is gradually increased from bottom to top and the small diameter portion 3 is formed.
1, a middle diameter part 32, and a large diameter part 33,
In addition, the nozzle 6 has a small inner diameter portion 35, a resin reservoir 36, a middle inner diameter portion 37, a tapered portion 38, and a large inner diameter portion 39 whose inner circumferences are from top to bottom.
Configuration. Further, by disposing the center core pin 2 at the center of the nozzle 6, the molten resin is discharged between the small inner diameter portion 35 at the tip of the nozzle 6 (small inner diameter portion 35 of the upper die B) and the outer peripheral surface of the center core pin 2. A ring-shaped injection port 26 for injection is formed. The tip of the center core pin 2 protrudes slightly below the injection port 26.

Here, the small diameter portion 31 has a slightly smaller diameter than the small inner diameter portion 35, the middle diameter portion 32 has a slightly smaller diameter than the middle inner diameter portion 37, and the tip (lower end) of the small diameter portion 31.
A line segment connecting 31a and the tip (lower end) 32a of the middle diameter portion 32 is inclined by an angle α2 with respect to the nozzle axis (the center axis of the nozzle 6), while the inclination of the tapered portion 38 of the nozzle 6 outside the line segment When the angle is α1, α2> α1.

As a result, only the ring gate 3 is lowered, and the small-diameter portion 31 is formed by the injection port 26 formed by the small-diameter portion 35.
, The injection of the resin is stopped due to the extremely small gap and the viscosity of the resin. As a result, the ring gate 3 can be raised and lowered smoothly without touching the inner surface of the nozzle 6. The thickness t (shown in FIG. 2) of the small-diameter portion 31, the value of the small-diameter portion 35, and the diameter of the center core pin 2 can be appropriately set according to the shape, thickness, size, and the like of the molded product.

Next, the good heat conducting member provided on the center core pin 2 and the lower mold B will be described. The center core pin 2 is made of carbon steel for machine structure (S-C, JIS), and a copper rod 41 as a good heat conducting member is provided at the lower end of the center core pin 2.
Type. Further, a brass (seven brass) plate 42 as a good heat conducting member is embedded in the bottom of the concave portion 12 of the lower die B. The brass plate 42 is also a soft material. Next, the groove 10 for preventing the solidified layer from peeling will be described with reference to FIGS. 3 shows a state where the ring gate 3 is located at the uppermost end, and FIG. 4 shows a state where the ring gate 3 is located at the lowermost end.

The groove 10 for preventing the solidified layer from peeling is located on the outer periphery of the center core pin 2 and in the retreat position P1 of the ring gate 3 from the vicinity of the injection port 26, that is, when the ring gate 3 moves upward to the uppermost end. It is provided between the lower end position P1. In other words, the solidified layer separation preventing groove 10 has a length substantially equal to the length of the stroke that the ring gate 3 moves when opening and closing the injection port 26, and the outer peripheral surface of the ring gate 3 comes into direct contact with the resin. A portion is provided along the outer periphery of the center core pin 2 in a concave shape in cross section. As a result, a skin-like solidified layer is generated at a position deeper than the level of the sliding surface of the ring gate 3, and it is possible to prevent the scraping.

The specific dimensions also depend on the temperature of the molten resin, the solidification point, the dimensions of the center core pin 2, and the like. For example, the diameter L1 of the center core pin 2 and the stroke L2 of the ring gate 3 may be determined according to the resin, and the length L3 and the depth W1 of the solidified layer separation preventing groove 10 may be determined accordingly. The depth W1 is preferably set to a depth such that even if the solidified layer 136 (see FIGS. 8 and 9) is generated, the solidified layer 136 does not reach the sliding surface level of the ring gate 3.

The upper and lower ends of the groove 10 for preventing separation of the solidified layer have tapered surfaces inclined inward at a predetermined angle in order to minimize interference between the ring gate 3 and the center core pin 2 when the ring gate 3 is raised and lowered. 43 are formed. The gap L4 between the ring-shaped injection ports 26 at this time is set to, for example, about 0.5 mm. In the figure, reference numeral 36 denotes a gap surrounding the tip of the nozzle 6, and by filling this portion with resin, the tip of the nozzle 6 is insulated so as not to be cooled by the cooling heat of the upper die B which is constantly cooled. The function of the material is demonstrated. The operation of the valve gate device described above will now be described. First, a general operation will be described.

FIGS. 5A and 5B are explanatory diagrams (first half) of the operation of the valve gate device according to the present invention. FIG. 5A shows a state in which the ring gate 3 is lowered with the molten resin flowing in the resin passage 9 in FIG. 1 to stop the flow of the resin, and in this state, the lower mold A is raised and overlapped with the upper mold B. In the state where the center core pin 2 has entered the concave portion 12 of the lower mold A, the upper mold B
This shows that a cavity 44 for a product has been formed between the lower mold A and the lower mold A.

Although the nozzle 6 is sufficiently heated by the heater 7, the temperature of the lower die A is much lower than that of the upper die B. Therefore, when the cooling action of the cold lower mold A is large, the resin at the tip of the nozzle 6 is solidified, which may hinder opening and closing of the ring gate 3. As a countermeasure, in this embodiment, a copper rod 41 and a brass plate 42 as a good heat conducting member are embedded. The copper rod 41 driven into the center core pin can transmit 7 times more heat to the carbon steel for machine structure (S-C, JIS) constituting the center core pin, and the brass embedded in the bottom of the recess 12. The plate 42 can also transmit approximately twice as much heat. Then, the resin in the vicinity of the small inner diameter portion 35 located at the tip of the center core pin 2 can be maintained at an appropriate resin temperature, and at the same time, the copper rod 41 can be maintained.
As soon as the abutment comes into contact with the brass plate 42, the heat held by the center core pin 2 is transmitted to the brass plate 42 via the copper rod 41, and the temperature of the concave portion 12 of the lower mold A rises within a very short time. As a result, lump of resin can be avoided.

In (b), when only the ring gate 3 is raised, a so-called valve open state is established, and the resin is
Flow into 4 and fill. FIGS. 6A and 6B are explanatory diagrams (second half) of the operation of the valve gate device according to the present invention.
In (a), when only the ring gate 3 is lowered, the valve is closed. In (b), the lower mold A is lowered as indicated by the white arrow. Thus, the molded article 45 can be paid out. Thereafter, FIG. 5 (a) → (b) → FIG. 6 (a) → (b) →
Injection molding can be carried out quickly by repeating as shown in FIG. 5 (a) → (b).

FIGS. 7A and 7B are views showing an example of a molded product obtained by the apparatus of the present invention. (A) shows a circular molded product 50 including a bottom 52 having a hole 51, a cylinder 53, and a wide flange 54. (B) is a bottle-formed product 6 having a hole 61.
Indicates 0. Thus, the perforated molded products 50 and 60 without welds or burrs can be effectively manufactured. The material of the center core pin, the material of the good heat conducting members 41 and 42, the shape and the mounting method thereof can be appropriately set.

Next, referring to FIGS. 8 and 9, the operation of the groove 10 for preventing the solidified layer from being peeled off provided on the center core pin 2 will be described. As shown in FIG. 8, the ring gate 3 is
When the injection port 26 of the nozzle 6 is opened at the uppermost position, the resin 66 is injected from the injection port 26 toward the cavity, and the resin 66 is solidified at the lower end of the center core pin 2, that is, solidified. It is in direct contact with the delamination preventing groove 10. In this case, for example, in the case of ABS resin, the resin 66 is heated to about 260 ° C. and maintains a molten state. However, since the center core pin 2 does not have a heater, the temperature tends to decrease. , For example, about 130 ° C. For this reason, the molten resin that has come into direct contact with the center core pin 2 tends to be cooled and solidified. Therefore, a thin solidified layer 136 of resin is generated at the bottom of the groove 10 for preventing solidified layer peeling.

In this case, in a device in which the groove 10 for preventing solidified layer peeling is not provided (see FIGS. 16 and 17), when the ring gate 3 is lowered for closing the valve, the solidified layer is cut out, resulting in a defective product. Although this is a cause, in the present invention, since the concave portion-shaped groove 10 for preventing solidified layer peeling is provided, the solidified layer 136 adheres to the bottom portion, and the solidified layer 136 is deeper than the sliding level of the ring gate 3. It will be located in the place. Therefore, even if the ring gate 3 is lowered as shown in FIG. 9, the solidified layer 136 is not cut off, and therefore, it is possible to suppress occurrence of defective products.

In this case, in order to reliably cut off the injected resin, the thickness W2 of the small inner diameter portion 35 in FIG. 3 depends on the resin, but may be at least about 0.01 mm, for example. The lowermost end P2 of the groove 10 for preventing the solidified layer from peeling is preferably positioned at least about 0.01 mm above the end face of the injection port 26 (the lower surface B1 of the upper die B in the cavity in FIG. 3). The position of the upper end of the groove 10 for preventing the solidified layer from peeling is located at the position P of the lower end of the ring gate 3 as shown in FIG.
It is preferable to make the value equal to 1, but to some extent, for example, several m
If it is about m, the position of the upper end of the solidified layer separation preventing groove 10 may be located below the position P1. However,
If the position of the upper end of the solidified layer separation preventing groove 10 is located above the position P1 as shown in FIG. 10, a resin stagnation portion 67 is formed inside the back surface, which may result in molding failure. . Further, in this case, since the support on the back surface side of the tip of the ring gate 3 is lost, the tip of the ring gate 3 becomes more fatigued and may not be able to withstand long-term use. The life is shortened.

Further, as described above, by providing the groove 10 for preventing the solidified layer from peeling, the drift of the resin flowing into the cavity can be suppressed, and the occurrence of flow marks on the molded product can be prevented. 11 and 12 are views for explaining this situation. FIG. 11 is a view showing the flow of the resin in the cavity when the solidified layer separation preventing groove is not provided on the center core pin, and FIG. It is a figure which shows the flow of the resin in a cavity when the groove | channel part for solidification layer peeling prevention is provided in the center core pin like the apparatus of this invention. In the illustrated example, in order to clarify the difference in the resin flow, the shape of the cavity is made different from that of the previous embodiment, and is made cylindrical. In the figure, the length of the arrow visually represents the flow rate of the resin.

As shown in FIG. 11, when a groove for preventing solidified layer peeling is not provided at the tip of the center core pin 2,
Immediately below the injection port 26 of the nozzle 6, the cavity 68
While the flow velocity of the resin inside is large, the flow velocity of the resin flowing downward gradually decreases from the direction immediately below the injection port 26 toward the outer periphery in the cavity 68. For this reason, at the portion where the inflowing resin comes into contact with the outer peripheral wall in the cavity 68, the resin is cooled by the lower mold A in a state where the flow rate of the resin is relatively slow, so that a flow mark is generated on the appearance of the molded product, and In some cases, it caused a defect.

On the other hand, when the solidified layer separation preventing groove 10 is provided at the tip of the center core pin 2 as in the apparatus of the present invention shown in FIG. 12, the solidified layer separation preventing groove 10 is formed at the lower end. The tapered portion 43 functions as a guide that regulates the flow direction of the resin, and the resin flows into the cavity 68 not obliquely downward but directly obliquely downward from the injection port 26. Therefore, as shown in the figure, the velocity of the resin flowing down in the cavity 68 is slightly higher on the outer peripheral side and slightly lower on the inner peripheral side. As a result, the velocity of the resin is substantially constant in the thickness direction in the cavity 68, and It is possible to suppress the occurrence of flow marks on the appearance of the product. In this case, if the depth of the solidified layer separation preventing groove 10 and the taper angle of the tapered portion 43 are appropriately adjusted, for example, if the depth is reduced and the taper angle is reduced, the flow component in the vertical direction (axial direction) is reduced. If the taper angle can be increased by increasing the depth or by increasing the depth, the flow component in the horizontal direction can be increased, and in any case, it can be appropriately selected depending on the product shape, the resin material used, and the like.

The shape of the molded article in the above-described embodiment is merely an example, and the present invention can be applied to any apparatus when producing a molded article having holes. Of course.

[0035]

As described above, according to the valve gate device of the injection molding machine of the present invention, the following excellent operational effects can be exhibited. By sliding the ring gate along the outer peripheral surface of the center core pin to close the nozzle outlet with a very small gap, the ring gate does not contact the nozzle even when the valve is closed, There is no need to worry about wear and the life can be extended.
Since the molten resin is directly injected into the cavity in a direction perpendicular to the radial direction of the center core pin from the injection port (small inner diameter portion) at the nozzle tip, welds, burrs, and uneven thickness can be sufficiently prevented. A perforated molded product having a good shape can be manufactured efficiently.

Further, since the solidified layer separation preventing groove is provided at the tip of the center core pin, the solidified layer of the resin adhering to the solid core layer is cut off, so that the solidified layer does not flow into the cavity. Can be prevented. In addition, since the heater is arranged on the outer periphery of the nozzle, the nozzle is heated by the heater on the outer periphery, and the ring gate is housed in the nozzle, so that the inner diameter of the nozzle is always larger than the outer diameter of the ring gate. The nozzle expands thermally, while the inside of the ring gate has a center core pin at a temperature slightly lower than the temperature held by the ring gate, so there is a small gap between the center core pin and the ring gate. In addition, since the outer periphery of the ring gate is made of only the resin in the molten state, the above-described operation ensures the smooth operation of raising and lowering the ring gate. Further, by appropriately adjusting the depth and the taper angle of the solidified layer separation preventing groove, the occurrence of a flow mark can be suppressed.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of a valve gate device according to the present invention.

FIG. 2 is an enlarged view of a main part of the apparatus shown in FIG.

FIG. 3 is an enlarged view of a portion shown in FIG. 2;

FIG. 4 is a diagram showing a state when a ring gate is lowered in a portion shown in FIG. 3;

FIG. 5 is an explanatory diagram (first half) of an operation of the valve gate device according to the present invention.

FIG. 6 is an operation explanatory view (second half) of the valve gate device according to the present invention.

FIG. 7 is a view showing an example of a molded product obtained by the apparatus of the present invention.

FIG. 8 is a view showing the operation of a characteristic portion of the device of the present invention.

FIG. 9 is a view showing the operation of a characteristic portion of the device of the present invention.

FIG. 10 is a view showing a state in which a groove for preventing solidified layer peeling of the present invention is elongated.

FIG. 11 is a diagram showing a flow of resin in a cavity when a solidified layer separation preventing groove is not provided.

FIG. 12 is a view showing a flow of resin in a cavity when a solidified layer separation preventing groove is provided.

FIG. 13 is an explanatory view of a conventional pin gate forming method.

FIG. 14 is an explanatory view of a conventional ring gate forming method.

FIG. 15 is an explanatory view of a conventional disk gate molding method.

FIG. 16 is an explanatory diagram showing the operation of the apparatus disclosed by the applicant previously.

FIG. 17 is an explanatory diagram showing the operation of the apparatus disclosed by the present applicant previously.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Valve gate device, 2 ... Center core pin, 3 ... Ring gate, 4 ... Piston, 5 ... Cylinder, 6 ... Nozzle, 7 ... Heater, 8 ... Manifold, 9 ... Resin passage, 1
0: solidified layer peeling prevention groove, 12: concave, 26: injection port, 31: small diameter part, 31a: tip of small diameter part, 32: medium diameter part, 32a: tip of medium diameter part, 33: large diameter part, 35 ... small inner diameter part, 37 ... middle inner diameter part, 38 ... taper part, 39 ... large inner diameter part, 41 ... good heat conduction member (copper bar), 42 ... good heat conduction member (brass plate), 43 ... taper part, 44 ... cavity, 4
5, 50, 60: molded product, 51, 61: hole, 66: resin, A: lower mold, B: upper mold.

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[Procedure amendment]

[Submission date] February 6, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

[Title of the Invention] Valve gate device of injection molding machine

Claims (2)

[Claims] 1. A nozzle for injecting a molten resin, a heater for heating the molten resin in the nozzle, and an outer peripheral surface inserted into the center of the nozzle for making a hole in a molded product. A center core pin that forms an injection port with the tip of the nozzle, and slides along the outer peripheral surface of the center core pin, and when the tip is located at the injection port, the outer peripheral face of the tip is the nozzle. A ring gate for stopping the flow of resin while keeping a very small gap with the tip of the cylinder, a cylinder and a piston for raising and lowering the ring gate to control the injection of the molten resin, and injecting the molten resin from the injection port In a valve gate device of an injection molding machine, a groove for preventing solidified layer peeling on an outer peripheral surface of the center core pin and between a position near the injection port and a position where the ring gate is retracted. A valve gate device for an injection molding machine, characterized by having a part. 2. The valve gate device for an injection molding machine according to claim 1, wherein said heater is arranged on an outer periphery of said nozzle.