JP2005119143A - Injection mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection mold constituted so as to prevent a molten resin from flowing in the mold in a hot runner mold and facilitating the uniform filling adjustment of the molten resin in a multi-cavity mold or a multi-point gate mold, so called the adjustment of gate balance. <P>SOLUTION: In this injection mold formed so as to extend a resin passage comprising a hot runner from the nozzle of a molding machine to a gate hole, the leading end part of a shank having the resin passage is inserted in the gate hole and an end cap, which is composed of a short cylinder part and the flange fitted to the peripheral surface on the side of a cavity of the gate hole fitted to each other in the gate hole, is attached to the leading end part of the shank so that the flange is fitted to the peripheral surface on the side of the cavity from the cavity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an injection mold, and in particular, for injection molding capable of preventing resin leakage of a hot runner mold and adjusting even filling of molten resin in a hot runner mold or a multi-point gate mold. Regarding molds.

Hot runner molds used for thermoplastic resin injection molding can keep the resin from the sprue and runner to the vicinity of the gate in a molten state, thereby shortening the molding cycle, and no sprue or runner is formed. It is often used in injection molding recently because it can be reduced and does not require post-processing.
In the hot runner mold, the molten resin injected and filled in the product-shaped cavity must be cooled and solidified before the product is taken out. Therefore, the gate part must be opened and closed by some means.

As shown in FIG. 6, the conventional hot runner mold is provided with a resin passage b just before the gate hole a, and a shank d heated by a heater c on the outside is disposed, and at the tip of the shank d, An end cap E is attached with a heat insulating gap e having a small clearance (for example, 20 to 40 μm) between the inner surface of the gate hole a. Since this mold has a simple structure and is inexpensive, it is often used as a mold for molding a general resin molded product.
However, when injection molding is performed using a resin with high fluidity, or when the injection pressure or holding pressure must be set high from the shape of the molded product, a small clearance between the gate hole a and the end cap E is required. The molten resin may flow into the heat insulating space on the outer periphery of the shank d.

  As another type of hot runner mold, there is a valve gate system in which a gate portion is mechanically opened and closed by a valve. As an example of this valve gate type mold apparatus, in order to prevent resin from flowing between a valve casing having a built-in valve pin and a heater cover covering the heater provided on the outer peripheral side thereof, an end portion on the cavity side of the heater cover The annular flange is bent to the inner peripheral side, a step surface facing the cavity side is formed on the outer periphery of the valve casing, and the inner peripheral surface of the annular flange is used as a column surface on the outer periphery of the valve casing. It has been proposed that the one end surface of the annular flange is brought into contact with the step surface (see, for example, Patent Document 1).

  In addition, as a mold for injection molding capable of adjusting the uniform filling of molten resin in a multi-cavity mold or a multi-point gate mold in a hot runner mold, “Hot runner branches from nozzle to multiple gates from molding machine nozzle. In the injection mold formed to extend, a manifold block having one end communicating with the molding machine nozzle and the other end branching to the same number as the plurality of gates, and being fixed to the manifold block, A plurality of branch blocks in which one end is connected to the other end of the manifold passage and the other end communicates with the gate, and a restriction is formed at each other end of the manifold passage. The hot runner is formed by nesting attached to the respective other end forming portions of the manifold block. Injection mold characterized in that it is. "Have also been proposed (e.g., see Patent Document 2.).

Japanese Patent Application Laid-Open No. 7-314500 (summary, see FIGS. 1 to 3). JP-A-5-237879 (refer to claim 1 and FIGS. 1 to 4).

  In the hot runner mold shown in FIG. 6, when the molten resin flows into the heat insulating space on the outer periphery of the shank d, the heat insulating performance is lowered, the molten resin temperature in the resin passage b is lowered, or conversely, the inflowing resin The temperature of the molten resin in the resin passage b becomes high due to overheating by the heater c of the heater, and the quality of an injection molded product to be molded next is hindered. There is a problem in that it becomes impossible to stably produce a molded product due to an abnormal detection of the heating temperature sensor of c.

Further, according to the proposal of Patent Document 1, the fitting between the two surfaces enhances the sealing property between the cavity side end portion of the heater cover and the valve casing, and the valve casing with the valve pin built therein is provided on the outer peripheral side thereof. Although the resin can be prevented from flowing into the heater cover that covers the heated heater, this valve gate does not prevent the resin from flowing into the mold from the cavity. Prevents direct contact with the heater.
Therefore, when resin flows into the mold from the valve gate, heat dissipation from the molten resin in the resin passage is increased by the flowed resin, resulting in unstable temperature control of the molten resin and stable production of the molded product. There was a problem that could not be.
Further, once the molten resin flows in from the gate portion, the mold clearance increases, and therefore, even if the flowed-in resin is removed, there is a problem that the molten resin is more likely to flow in the next molding.

  Further, according to the proposal in Patent Document 2, “the squeezing by nesting is formed at the end of the manifold passage on the branch passage side. If adjusted appropriately, it becomes possible to adjust the flow rate of resin to each gate, thereby making it possible to balance the gates between the gates. Since it is formed by nestings attached to each end, it is possible to freely recombine each nesting. For example, a plurality of nestings having different aperture shapes are prepared in advance. The gate balance can be adjusted with a simple operation by recombining them appropriately ”(paragraph 0009). It is to be able to carry out easily.

However, in order to change the nesting, it is necessary to disassemble the injection mold 10 on the fixed side and replace the nesting. Therefore, it is necessary to disassemble the mold, replace the nesting, and assemble the mold. Therefore, it is necessary to disassemble and assemble the mold, and there is a problem that man-hours and time are required for adjusting the gate balance.
It is sufficient if the gate balance can be adjusted by changing the nest once. However, as the number of gates increases, it is necessary to adjust the nest by changing the nest many times, so it takes time and man-hours to adjust the gate balance. was there.

  In the hot runner mold, the present invention prevents the molten resin from flowing into the mold, and facilitates the uniform filling adjustment of the molten resin in the multi-cavity mold or the multi-point gate mold, so-called gate balance adjustment. The purpose is to provide a simple mold.

  The injection mold according to the first aspect of the present invention is an injection mold in which a resin passage made of a hot runner extends from a molding machine nozzle to a gate hole, and a shank having a resin passage in the gate hole. The end cap is composed of a short cylinder part that fits into the shank tip part in the gate hole and a flange that abuts the peripheral surface of the gate hole on the cavity side. The short cylinder portion is fitted to the shank tip so as to abut the peripheral surface, and is attached.

  According to the first aspect of the present invention, the end portion of the shank having a resin passage is inserted into the gate hole, and the end cap including the short tube portion and the flange is inserted into the shank distal end portion from the cavity side, and the flange is connected to the cavity side. Since the short cylinder part is fitted to the tip of the shank so as to abut the peripheral surface, the flowability of the resin used for injection molding is high, and the injection pressure and holding pressure can be set high. Even if necessary, the molten resin does not flow into the mold due to the pressure of the resin injected into the cavity, so that the edge of the end cap is pressed against the cavity side peripheral surface of the gate hole. Can be kept stable, and a molded product with stable quality can be formed.

  According to a second aspect of the present invention, there is provided an injection molding die according to the present invention, wherein the resin passage formed of a hot runner extends from the molding machine nozzle to the gate hole. A shank tip portion having a resin passage is formed in the shank tip portion, and a short cylinder portion having a male screw and a resin passage threaded into the female screw hole, and a gate. An end cap consisting of a flange that abuts the cavity-side peripheral surface of the hole is threaded from the cavity side so that the flange is abutted with the cavity-side peripheral surface, and the short threaded male screw is screwed into the female screw hole at the shank tip. It is characterized by being attached together.

  According to the second aspect of the present invention, since the end cap is in a state of covering the gate hole, the molten resin flows into the mold even when the resin fluidity is high or the injection pressure or holding pressure is high. Therefore, it is possible to mold a molded product with stable quality by keeping the temperature of the molten resin in the resin passage stable.

According to a third aspect of the present invention, there is provided an injection mold according to the second aspect, wherein a square hole is formed in the end face of the end cap and a square spanner is provided in the square hole. The end cap is fitted into the female screw hole at the tip of the shank and can be attached and detached.
Since a square hole is formed in the end face of the end cap, a square spanner can be fitted into this square hole so that the end cap can be attached to and detached from the female screw hole at the tip of the shank, and attachment and removal are easy.

According to a fourth aspect of the present invention, there is provided an injection mold according to any one of the first to third aspects, wherein the gate hole has a peripheral surface on the cavity side and an end that abuts on this surface. The cap surface is a conical surface.
Since the cavity side peripheral surface of the gate hole and the flange surface of the end cap that abuts on this surface are conical surfaces, the surfaces are pressed against each other without gaps, so that the molten resin does not flow into the mold. The molten resin temperature in the passage can be kept stable, and a molded product with stable quality can be molded.

  The injection mold of the present invention according to claim 5 is an injection mold in which a resin passage made of a hot runner extends from a molding machine nozzle to a plurality of gate holes. A shank tip having a resin passage is located on the shank, and a female screw hole having a diameter smaller than that of the gate hole with the resin passage center axis as an axis is formed at the tip of the shank. An end cap made of a short cylindrical body is inserted from the cavity side so as to close the gate hole, and is attached by screwing a male screw into a female screw hole at the tip of the shank.

  According to the fifth aspect of the present invention, the shank tip portion having the resin passage is located inside each gate hole, and the female screw hole formed in the shank tip portion comprises the short cylinder having the male screw and the resin passage. The end cap is inserted from the cavity side so as to block the gate hole, and the male screw is screwed into the female screw hole at the tip of the shank, so that the mold is mounted with the mold attached to the molding machine. When opened, this end cap can be replaced without disassembling the mold. By replacing the end cap with an end cap with a different resin passage diameter, a multi-piece mold or multi-point gate mold can be used. The mold can be adjusted so that the molten resin can be uniformly filled in the cavities, and the uniform filling adjustment of the molten resin can be easily performed.

According to a sixth aspect of the present invention, there is provided an injection mold according to the fifth aspect of the present invention, wherein the end cap is formed with a square hole on the end surface opposite to the male screw, and the square hole has a corner. A spanner is fitted, and the end cap can be attached to and detached from the female screw hole at the tip of the shank.
A square hole is formed in the end face opposite to the male screw of the end cap, and a square spanner is fitted into this square hole so that the end cap can be attached to and detached from the female screw hole at the tip of the shank, and attachment and removal are easy.

According to a seventh aspect of the present invention, there is provided an injection molding die according to the fifth or sixth aspect, wherein various end caps having different resin passage diameters are prepared, The end caps having different resin passage diameters can be replaced from the cavity side so that the molten resin is uniformly filled.
Various end caps with different resin passage diameters are prepared in this way, and this end cap can be replaced from the cavity side, so if the mold is opened, without disassembling the mold, The end cap can be easily replaced and adjusted so that the molten resin is evenly filled from each gate hole.

  The best mode will be described below based on examples.

  1 and 2 show a first embodiment of an injection mold according to the present invention, which is an embodiment corresponding to claim 1, FIG. 1 is a sectional view showing the whole injection mold, and FIG. 2 shows the present invention. It is sectional drawing which expands and shows simplified the principal part of these.

In FIG. 1, 1 is a fixed type and 2 is a movable type. The fixed mold 1 has a nozzle receiving portion 11 of an injection molding machine, and is provided with a manifold 13 and shanks 14 and 14 for distributing molten resin in a fixed side receiving plate 12, and the manifold 13 and shanks 14 and 14 are arranged on the outer periphery. A heater is attached to the resin, and the resin flowing inside is heated to be controlled at a resin temperature suitable for injection molding at all times. A gate hole 15 is formed at the tip of the shank 14. Thus, the manifold 13 and the shanks 14 and 14 are controlled by heating so that a resin passage made of a hot runner extends from the molding machine nozzle to the gate hole 15 in the mold.
A fixed-side cavity block 16 is attached to the fixed mold 1, and a shank 14 is inserted into the fixed-side cavity block 16.
In addition, although this injection-molding die is for injection-molding two molded products at the same time, it may be one or three or more at the same time.
Further, two or more gate holes 15 may be provided for one molded product.

The movable mold 2 includes a movable side receiving plate 21 equipped with a protruding plate 22, a protruding pin 23, a support block 24, a limiter block 25 and the like, and a movable side cavity block 26 is attached to the movable side receiving plate 21. .
Reference numerals 17 and 27 denote cavity inserts attached to the fixed cavity block 16 and the movable cavity block 26. By replacing the cavity inserts 17 and 27, molded products of various shapes and sizes can be obtained. It can be molded. That is, it is expensive to replace the cavity blocks 16 and 26 to form molded products having different shapes and structures. However, if the cavity inserts 17 and 27 are only replaced, It can be easily changed.

Reference numeral 3 denotes a core, which is disposed in the cavity inserts 17 and 27 to form an inner peripheral surface when a cylindrical molded product is injection-molded. A cylindrical molded product can be molded by injecting into the cavity 4 formed by the core 3 and the cavity inserts 17 and 27 molten resin that is heated and controlled at a resin temperature suitable for injection molding into the resin passage. .
Further, when forming an electric fusion joint in which a heating wire is spirally embedded on the inner peripheral surface for fusion-bonding polyethylene tubes to each other, first, a thin wall that is externally fitted to the core 3 and spiral on the outer periphery. A cylindrical body provided with a groove is formed, and this cylindrical body is fitted onto the core 3 and a heating wire is wound around the spiral groove. The core 3 is disposed in the cavity inserts 17 and 27, and the resin temperature is controlled to be appropriate for injection molding through the gate hole 15 in the cavity 4 formed by the cylindrical body and the cavity inserts 17 and 27. By injecting the molten resin, a thick cylindrical body is formed, and an electric fusion joint having a heated electric wire wound spirally near the inner peripheral surface can be formed.

  The fixed mold 1 is provided with a guide hole 18, and the movable mold 2 is provided with a guide pin 28, and the guide pin 28 of the movable mold 2 slides within the guide hole 18 of the fixed mold 1 to open and close. Thus, the movable mold 2 can always be opened and closed accurately with respect to the fixed mold 1. That is, the cavity 4 is formed in an accurate shape, and a molded product having the same shape can always be formed.

  Next, the invention according to claim 1 will be described with reference to FIG. FIG. 2 is an enlarged and simplified sectional view of the gate hole 15 and the cavity 4 at the tip of the shank 14 of FIG. That is, there is shown an example in which the core 3 is not provided and the plate-like cavity 4 is formed by the cavity inserts 17 and 27 (may be the cavity blocks 16 and 26).

In FIG. 2, the cavity 4 is formed by a cavity insert 17 attached to the fixed cavity block 16 and a cavity insert 27 attached to the movable cavity block 26, and the cavity insert 17 includes a gate hole. 15 is formed. The cavity insert 17 and the fixed cavity block 16 are provided with an insertion hole 20 for the shank 14, and the shank 14 is attached thereto. A heater 19 is attached to the outer periphery of the shank 14, and the resin in the shank 14 is always controlled to be heated to a resin temperature suitable for injection molding.
A thin diameter portion 141 is formed at the tip of the shank 14, and the thin diameter portion 141 is inserted into the gate hole 15. A resin passage 5 is formed in the shank 14, and the resin passage 5 communicates with the injection molding machine through the manifold 13 and the nozzle receiving portion 11.

Reference numeral 6 denotes an end cap, which includes a short cylindrical portion 61 having an outer diameter that fits into the gate hole 15 and a flange 62 that abuts the peripheral surface of the gate hole 15 on the cavity 4 side. A through-hole 63 that fits into the diameter portion 141 is formed.
In the embodiment shown in FIG. 2, the position of the cavity 4 where the gate hole 15 is provided is a space having a large size, and an annular flat portion is formed on the side of the cavity 4 of the gate hole 15. No. 62 of the swords will come in contact.

In the embodiment shown in FIG. 2, when injection molding is performed, when molten resin is injected by an injection molding machine, the molten resin heated and controlled at a resin temperature suitable for injection molding in the resin passage is contained in the shank 14. The resin is injected from the resin passage 5 into the cavity 4. When the injection is finished, the injection pressure by the injection molding machine is eliminated. When holding pressure is required after injection of the molten resin, the injection pressure is eliminated after a time for holding pressure.
An end cap 6 is attached to the tip of the shank 14 where the molten resin is injected. Even if the pressure of the injected molten resin increases, the flange 62 of the end cap 6 is surrounded by the resin pressure around the cavity 4 side. The injected molten resin is prevented from leaking from the gap between the gate hole 15 and the end cap 6 into the insertion hole 20 for mounting the shank 14 provided in the fixed side cavity block 16 from the gap between the gate hole 15 and the end cap 6. .
If there is no leakage of the molten resin, the molten resin in the resin passage in the shank 14 is heated to an appropriate resin temperature by the heater 19, so that when the molded product is cooled in the mold, the mold opens. When the molded product is taken out and the mold is closed, the next injection molding can be performed immediately.

  FIG. 3 shows a second embodiment of the injection mold of the present invention, which is an embodiment corresponding to claim 2 and a cross-sectional view corresponding to FIG.

Only differences from FIG. 2 will be described with reference to FIG.
In this embodiment, the tip of the shank 14a is located inside the gate hole 15a, and the end cap 6a is screwed onto the tip of the shank 14a.
A female screw hole 142 having the central axis of the resin passage 5a as an axis is formed at the tip of the shank 14a. On the other hand, in the end cap 6a, a male screw 64 is formed on the outer periphery of the end of the short cylinder portion 61a opposite to the flange 62a. The male screw 64 is inserted through the gate hole 15a and screwed into the female screw hole 142 at the tip of the shank 14a. In combination, the end cap 6a is attached to the shank 14a.

Reference numeral 66 denotes a resin passage formed in the end cap 6a, which is smoothly connected to the resin passage 5a of the shank 14a.
A square hole 65 is provided on the flange 62a side of the end cap 6a. A square spanner is fitted into the square hole 65 so that the end cap 6a can be screwed together.
Also in this embodiment, the flange 62a of the end cap 6a is pressed against the peripheral surface of the gate hole 15a on the cavity 4a side, and the injected molten resin enters the fixed cavity block 16a from the gap between the gate hole 15a and the end cap 6a. Leakage into the insertion hole 20a for mounting the provided shank 14a is prevented.

FIG. 4 shows a third embodiment corresponding to claim 4 and is a sectional view corresponding to FIG.
In this example, the peripheral surface on the cavity 4b side of the gate hole 15b and the flange surface on the gate hole 15b side of the flange 62b of the end cap 6b are conical surfaces 7.
In this example, the flange surface of the end cap 6b and the peripheral surface of the gate hole 15b are pressed into contact with each other at the conical surface 7 without any gap, so that the inflow of resin is prevented.
Also in this example, the resin passage 66b of the end cap 6b is smoothly connected to the resin passage 5b of the shank 14b.

  FIG. 5 shows a fourth embodiment of an injection mold according to the present invention, which is an embodiment corresponding to claim 5 and a sectional view corresponding to FIG.

Only differences from FIG. 3 will be described with reference to FIG.
In this embodiment, the tip end of the shank 14c is located inside the gate hole 15c, the end cap 6c is composed of a short cylindrical portion 61c without a flange 62a, and the end cap 6c is screwed and attached from the cavity 4c side. This is an example.
In this embodiment, in a mold for simultaneously injection-molding a plurality of molded products, adjustment is made so that the injection amount of resin to each mold is appropriately distributed, or a plurality of gate holes 15c are provided in one molded product. It is provided and is useful when adjusting the so-called gate balance, such as when adjusting the injection amount of the resin to be appropriately distributed to each gate hole 15c.

A female screw hole 142c is formed at the tip of the shank 14c with the central axis of the resin passage 5c as an axis. On the other hand, the end cap 6c is composed of a short cylindrical body 61c having no wrinkles, and a male screw 64c is formed on the outer periphery of one end thereof. The end cap 6c is attached to the shank 14c.
A resin passage 66c of molten resin is formed in the end cap 6c. The resin passage 66c is reduced in diameter or enlarged at the end of the resin passage 66c on the side of the shank 14c so as to be smoothly connected to the resin passage 5c provided in the shank 14c.
A square hole 65c is provided on the end face of the end cap 6c opposite to the male screw 64c. A square spanner is fitted into the square hole 65c so that the end cap 6c can be screwed together.

In this embodiment, when the distribution of the amount of molten resin injected and injected from each gate hole 15c is not appropriate, and when a shortage of filled resin occurs in a certain gate hole 15c, various end caps 6c having different diameters of the resin passage 66c are used. The end cap 6c attached to the gate hole 15c where the filling resin shortage has occurred is removed from the cavity 4c side with the mold opened, and the end cap with a large diameter of the resin passage 66c is prepared. Replace with 6c.
If the gate balance cannot be adjusted by simply replacing one end cap 6c, the end caps 6c can be replaced with ones having different diameters and molded again, so that the resin can be evenly filled. adjust.

  In this embodiment, since the end cap 6c can be replaced from the cavity 4c side, in the mold having the plurality of gate holes 15c, it is possible to open the mold without disassembling the mold. It is possible to adjust the filling of the resin to be equal only by replacing the end cap 6c.

Further, in this embodiment, as the end cap 6c, the flange 62a or 62b is the peripheral surface on the cavity side of the gate hole 15a or the gate hole 15b as in the end cap 6a or 6b shown in FIG. The resin passage 66 or 66b may have various diameters.
In this example, since the flange surface of the end cap 6a or 6b and the peripheral surface of the gate hole 15a or 15b are pressed into contact with each other with an annular flat surface or a conical surface, the inflow of resin is prevented and the mold is opened. The resin filling can be adjusted to be equal only by replacing the end cap 6a or 6b without disassembling the mold simply by setting the state.

1 shows a first embodiment of an injection mold according to the present invention, which is an embodiment corresponding to claim 1, and FIG. 1 is a cross-sectional view showing the whole injection mold. It is sectional drawing which expands and shows the principal part of this invention shown in FIG. 1 in a simplified manner. FIG. 3 shows a second embodiment of the injection mold according to the present invention, which is an embodiment corresponding to claim 2 and a cross-sectional view corresponding to FIG. 2. FIG. 5 shows a third embodiment of the injection mold according to the present invention, which is an embodiment corresponding to claim 4 and a cross-sectional view corresponding to FIG. 2. 4 shows a fourth embodiment of an injection mold according to the present invention, which is an embodiment corresponding to claim 5 and a cross-sectional view corresponding to FIG. It is sectional drawing which shows the structure of the gate hole vicinity of the conventional hot runner metal mold | die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixed type 11 Nozzle receiving part 12 Fixed side receiving plate 13 Manifold 14 Shank 15 Gate hole 16 Fixed side cavity block 17 Cavity insert 18 Guide hole 19 Heater 2 Movable type 21 Movable side receiving plate 26 Movable side cavity block 27 Cavity insertion Child 28 Guide pin 3 Core 4 Cavity 5 Resin passage in shank 6 End cap 61 Short cylindrical body 62 鍔 66 End cap resin passage

Claims (7)

  In a mold for injection molding formed so that a resin passage made of a hot runner extends from a molding machine nozzle to a gate hole, the tip of a shank having a resin passage is inserted into the gate hole, and the inside of the gate hole is inserted into the shank tip. The end tube consisting of a short tube part that fits in and a flange that butts against the cavity side peripheral surface of the gate hole, from the cavity side, butt the rivet to the peripheral surface of the cavity side, and the short cylinder part is connected to the tip of the shank. An injection mold characterized by being fitted to a part and attached.   In a mold for injection molding formed so that a resin passage made of a hot runner extends from a molding machine nozzle to a gate hole, a shank tip having a resin passage is located inside the gate hole, and the resin passage is located at the shank tip. A female screw hole having a central axis as an axis is formed, and an end cap including a male screw threaded into the female screw hole, a short cylindrical portion having a resin passage, and a flange that abuts against the cavity side peripheral surface of the gate hole. An injection mold characterized in that, from the cavity side, the male screw of the short cylinder part is screwed into the female screw hole of the shank tip part so as to abut against the peripheral surface of the cavity side. .   3. An injection molding metal according to claim 2, wherein a square hole is formed in the flange side end surface of the end cap, and a square spanner is fitted into the square hole so that the end cap can be attached to and detached from the female screw hole at the tip of the shank. Type.   The injection mold according to any one of claims 1 to 3, wherein the cavity side peripheral surface of the gate hole and the flange surface of the end cap that abuts on this surface are conical surfaces.   In a mold for injection molding formed so that a resin passage made of a hot runner extends from a molding machine nozzle to a plurality of gate holes, a shank tip portion having a resin passage is located inside each gate hole, and this shank tip portion is Has a female screw hole having a smaller diameter than the gate hole with the resin passage center axis as an axis, and an end cap formed of a short cylinder having a male screw and a resin passage to be screwed into the female screw hole is connected to the gate from the cavity side. An injection mold, wherein the mold is inserted so as to close the hole, and the male screw is screwed into the female screw hole at the tip of the shank.   6. The injection molding according to claim 5, wherein a square hole is formed in an end face opposite to the male screw of the end cap, and a square spanner is fitted into the square hole so that the end cap can be attached to and detached from the female screw hole of the shank tip. Mold.   7. Various end caps having different resin passage diameters are prepared, and the end caps having different resin passage diameters are replaced from the cavity side so that molten resin is uniformly filled in each gate hole. Injection mold.

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