JP2020121476A - Injection mold - Google Patents

Abstract

To provide an injection mold capable of molding a long-sized cylindrical molded article including a thick part with excellent precision.SOLUTION: An injection mold 1 includes a first slide core 1A and a second slide core 1B. Each of the first slide core 1A and the second slide core 1B individually includes: a cylindrical part formation surface 4a; a projection part formation surface 4b; a flange part formation surface 4c; gate grooves 3A and 3B; and a runner groove 2A. The first slide core 1A and the second slide core 1B abut on each other at parting surfaces 1c, a combination of the runner grooves 2A forms a runner RA, and a combination of the gate grooves 3A forms a plurality of gates GA and GB. An injection resin is split through the runner RA to the plurality of gates GA and GB.SELECTED DRAWING: Figure 1

Description

The present invention relates to an injection mold.

When molding a long tubular member by injection molding, as disclosed in Patent Document 1, it is proposed to provide a gate in a mold on a molding surface corresponding to one end of the tubular member in the axial direction. ing.

JP, 2002-283406, A

However, the related art as described above has the following problems.
In the technique described in Patent Document 1, the length that the resin can flow is determined by the wall thickness of the tubular member. Therefore, the thinner the tubular member is, the more difficult it is to lengthen the tubular member.
In particular, when the wall thickness of the tubular member changes stepwise in the axial direction, the flow of the injection resin in the molding space corresponding to the shape of the molded product is disturbed. The injection resin filling balance in the molding space is lost. As a result, the dimensional accuracy of the molded product may decrease.
In the technique described in Patent Document 1, in particular, it is not possible to accurately form a shape in which thick projections such as fins, flanges, and screws project from a long tubular member.
In order to accurately form a long tubular member having a thick portion protruding, the cylinder body and the thick portion are manufactured separately and then bonded to each other. In this case, since the bonding process takes time, there is a problem that the manufacturing time is increased as compared with the case of integrally molding by injection molding.

The present invention has been made in view of the above problems, and an object thereof is to provide an injection molding die capable of accurately forming a long tubular molded article including a thick portion. To do.

In order to solve the above problems, the injection mold of the first aspect of the present invention is an injection mold for forming a molded product, the molded product having a tubular portion and a thickness of the tubular portion. A plurality of first thick-walled portions that are thick, the plurality of first thick-walled portions project from the surface of the tubular portion, and the plurality of injection-molding dies contact each other on the parting surface. A plurality of slide cores, wherein the plurality of slide cores include a first molding surface for molding an outer peripheral surface of the molded product in a portion excluding the plurality of first thick portions, and the plurality of first thick portions. A plurality of second molding surfaces for molding the respective outer peripheral surfaces of the, and a plurality of gate grooves formed in the parting surface and opening in each of the plurality of second molding surfaces; A runner groove having an injection port through which a resin is injected and including a runner groove that opens into the plurality of gate grooves, respectively, and a runner is formed by combining the runner grooves in adjacent slide cores of the plurality of slide cores. A plurality of gates are formed by combining the gate grooves of the adjacent slide cores, and the injection resin is divided into the plurality of gates through the runner.

In the injection molding die, in each of the plurality of slide cores, the plurality of second molding surfaces correspond to each other in the arrangement of the plurality of first thick portions in the axial direction of the first molding surface. The runner grooves may be arranged apart from each other, and may extend linearly in the axial direction along the arrangement of the plurality of gate grooves.

In the injection molding die, the runner may include a flow adjustment flow path section that equalizes the arrival time of the injection resin from the injection port to each of the plurality of gates.

In the injection-molding die, the plurality of slide cores correspond to the molded article further including a second thick portion having a thickness larger than a thickness of the tubular portion, and the slide core includes the second thick portion. The outer peripheral surface of the two thick portions may be molded, and a third molding surface in which the plurality of gates are not opened may be further provided.

In the injection molding die, the plurality of gates may be arranged at equal intervals in the axial direction.

In the injection-molding die, the plurality of second molding surfaces are sandwiched between a tip surface forming a tip in the depth direction from the first molding surface and the tip surface in a direction intersecting the depth direction. A gate, which includes a third molding surface having a side surface, and which is open to the third molding surface among the plurality of gates may be opened to the inner side surface.

In the injection molding die, the gate may be opened to the third molding surface at a position closer to the first molding surface than the tip surface in the depth direction.

According to the injection molding die of the present invention, it is possible to accurately form a long tubular molded product including a thick portion.

It is a typical perspective view showing an example of an injection mold of a 1st embodiment of the present invention. FIG. 3 is a schematic partial cross-sectional view of a molded product manufactured by the injection molding die according to the first embodiment of the present invention. It is a schematic front view of the injection-molding die of the 1st Embodiment of this invention. It is a typical perspective view of the molded product manufactured with the injection molding metallic mold of the 2nd embodiment of the present invention. It is a typical perspective view showing an example of an injection mold of a 2nd embodiment of the present invention. FIG. 11 is a schematic perspective view of a molded product manufactured by the injection molding die according to the third embodiment of the present invention. It is a typical perspective view showing an example of an injection mold of a 3rd embodiment of the present invention. It is a typical sectional view of the cast manufactured with the injection molding metallic mold of the 4th embodiment of the present invention. It is a typical perspective view showing an example of an injection mold of a 4th embodiment of the present invention. It is a typical front view which shows an example of the principal part of the injection molding metal mold|die of the 5th Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In all the drawings, the same or corresponding members are denoted by the same reference numerals even if the embodiments are different, and common description is omitted.

[First Embodiment]
The injection molding die according to the first embodiment of the present invention will be described.
FIG. 1 is a schematic perspective view showing an example of an injection molding die according to the first embodiment of the present invention. FIG. 2 is a schematic partial cross-sectional view of a molded product manufactured by the injection molding die according to the first embodiment of the present invention. FIG. 3 is a schematic front view of the injection molding die according to the first embodiment of the present invention.

As shown in FIG. 1, the injection mold 1 of this embodiment includes a first slide core 1A (slide core), a second slide core 1B (slide core), and a core 1C. Although not particularly shown, the injection molding die 1 further includes known members such as a fixed-side mold plate, a cavity mold, and a movable-side mold plate.
The injection mold 1 is used for the purpose of manufacturing a molded product 54 by injection molding.
The molded product 54 can have any suitable shape having a tubular portion and a plurality of thick portions protruding from the tubular portion.
The wall thickness of the tubular portion is constant in the axial direction of the tubular portion. The cross-sectional shape of the tubular portion is not particularly limited. For example, the cross-sectional shape of the tubular portion may be a circle, an ellipse, a polygon, a half moon, or the like.
The plurality of thick portions may have the same shape or may not have the same shape. The specific shape of each thick portion is not particularly limited. For example, the shape of the thick portion may be trapezoidal, strip-shaped, dot-shaped, rod-shaped, dome-shaped, or the like. For example, the shape of the thick portion may be a plate shape such as a flange shape, a fin shape, or a screw shape.
The plurality of thick portions are arranged apart from each other in at least one of the axial direction and the circumferential direction of the tubular portion.
) In the present specification, the thick portion means a portion where the flow path in the flow direction of the injection resin is thicker than the thickness of the tubular portion. For example, the thick portion is formed by a projection shape that makes the tubular portion thicker and more uneven. For example, the thick-walled portion is formed by a plate-shaped, rod-shaped, or other protrusion itself having a thickness greater than that of the tubular portion.
The molded product 54 may be provided with a protrusion that does not correspond to the above-mentioned thick portion,
Hereinafter, as an example, a case where the molded product 54 has a shape shown in FIGS. 1 and 2 will be described.

In the example shown in FIG. 2, the molded product 54 has a tubular portion 54a, a protrusion 54b (first thick portion), and a flange portion 54c (first thick portion).
The tubular portion 54a is a cylinder extending along the central axis O. The inner diameter of the tubular portion 54a is D, the wall thickness is t, and the length is L.
For example, L may be 50 mm or more. D may be 5 mm or more and 50 mm or less. t may be 0.1 mm or more and 2 mm or less.

The protruding portion 54b projects in the radial direction from the outer peripheral surface 54d of the tubular portion 54a over the entire circumference of the outer peripheral surface 54d. The shape of the protrusion 54b in a cross section including the central axis O is a w1×h1 rectangle. Here, w1 represents the axial width, and h1 represents the protrusion height from the outer peripheral surface 54d. The tip end surface of the protruding portion 54b in the protruding direction is a cylindrical surface coaxial with the central axis O. The outer diameter of the tip surface of the protrusion 54b is D+t+h1. In the axial range in which the protrusion 54b is formed, the thickness of the molded product 54 is t+h1.
The sizes of w1 and h1 are not particularly limited. For example, in the example shown in FIG. 2, t<h1<w1.

The flange portion 54c has the same shape as the protrusion portion 54b except that the size of the cross section including the central axis O is different.
The shape of the flange portion 54c in a cross section including the central axis O is a w2×h2 rectangle. In the example shown in FIG. 2, t<w2<w1 and h1<h2. Here, w2 represents the width in the axial direction, and h2 represents the protrusion height from the outer peripheral surface 54d. The tip end surface of the flange portion 54c in the projecting direction is a cylindrical surface coaxial with the central axis O. The outer diameter of the front end surface of the flange portion 54c is D+t+h2.

As described above, in the example shown in FIG. 2, the protrusion 54b is a strip-shaped protrusion extending on the outer peripheral surface 54d in the circumferential direction. On the other hand, the flange portion 54c is a plate-shaped projection that protrudes radially outward from the outer peripheral surface 54d along a plane orthogonal to the central axis O, in a ring shape.
It can be said that the protrusion 54b itself is a thick portion. However, since the aspect ratio of the protruding shape is low, it can be said that the protruding portion 54b is a thick portion in which the cylindrical shape has an uneven thickness, depending on the specific size of h1 and w1.
On the other hand, since the flange portion 54c has a high aspect ratio in the protruding shape, the flange portion 54c itself is a plate-shaped thicker portion than the tubular portion 54a.

The number and the arrangement interval of the protrusions 54b and the flanges 54c are not particularly limited.
In the example shown in FIG. 2, three protrusions 54b and two flanges 54c are formed. The protrusions 54b and the flanges 54c are arranged alternately in the axial direction of the tubular portion 54a. The arrangement interval between the protrusion 54b and the flange 54c is a constant value LT.

The protrusion 54b and the flange 54c described above have an undercut shape in the case of a die configuration in which the axial direction of the molded product 54 is the pulling direction.
The thick portion may project from the inner peripheral surface 54e. However, in the example shown in FIG. 2, no protrusion is formed on the inner peripheral surface 54e.

The material of the molded product 54 is not particularly limited as long as it is a resin material that can be injection-molded. The material of the molded product 54 may be a hard resin material or a soft resin material such as an elastomer.

Next, the injection mold 1 of this embodiment will be described.
In the following, description may be made with reference to the XYZ orthogonal coordinate system shown in FIG. The Z axis is an axis extending in the moving direction of the movable mold plate or the like. The X axis is an axis line orthogonal to the Z axis. The Y axis is an axis line that is orthogonal to the X axis in a plane that includes the X axis and is orthogonal to the Z axis. The directions along the X axis, the Y axis, and the Z axis are referred to as the X direction, the Y direction, and the Z direction, respectively.

The first slide core 1A and the second slide core 1B are arranged to face each other in the Y direction. The first slide core 1A and the second slide core 1B are slidable in at least the Y direction when the injection molding die 1 is opened and closed.
The core 1C is arranged along an axis parallel to the Z axis. The core 1C is fixed to the movable-side template and is movable in the Z direction together with the movable-side template.

The first slide core 1A and the second slide core 1B form the shape of the outer peripheral portion of the molded product 54.
The shapes of the first slide core 1A and the second slide core 1B are plane-symmetric with respect to a plane parallel to the ZX plane. Hereinafter, the shape of the first slide core 1A will be mainly described.

The outer shape of the first slide core 1A is a substantially rectangular parallelepiped elongated in the Z direction. A first end face 1a parallel to the XY plane is formed at the Z-direction end of the first slide core 1A. The first end surface 1a faces a fixed-side mold plate (not shown) of the injection mold 1 when the mold is closed.
A second end face 1b parallel to the XY plane is formed at the end opposite to the first end face 1a in the Z direction. The second end surface 1b is in contact with a movable side mold plate (not shown) in the injection molding die 1 when the mold is closed.
A parting surface 1c is formed on the surface of the first slide core 1A facing the second slide core 1B. The parting surface 1c is a plane parallel to the XZ plane.

Each parting surface 1c is formed with a recess that forms the outer shape of the molded product 54 when the injection molding die 1 is closed. A molding space for molding the molded product 54 is formed between the recess and the core 1C.
Each parting surface 1c is formed with a recess that forms a resin flow path for filling the molding space with the molding resin.
The recess forming the molding space includes a cylindrical portion molding surface 4a (first molding surface), a protrusion molding surface 4b (second molding surface), and a flange molding surface 4c (second molding surface).
The concave portion forming the resin flow passage is composed of a first resin flow passage portion P1 and a second resin flow passage portion P2.

The cylindrical portion molding surface 4a forms the shape of a half circumference portion of the outer peripheral surface 54d of the tubular portion 54a. The cylindrical portion molding surface 4a is a semicircular groove extending in the Z direction about the central axis OA. In the present specification, the semicircular groove is defined as a groove having a semicircular cross-sectional shape orthogonal to the extending direction. In the semicircular groove, the radius of the semicircle in the cross section is called the groove radius.
The central axis OA extends parallel to the Z axis at the center of the parting surface 1c.
The groove radius of the cylindrical portion molding surface 4a is D/2. The cylindrical portion molding surface 4a penetrates between the first end surface 1a and the second end surface 1b in the Z direction. The length of the cylindrical portion molding surface 4a is equal to the total length L of the molded product 54.

As shown in FIG. 3, the projection molding surface 4b and the flange molding surface 4c are recesses formed on the parting surface 1c and the cylindrical molding surface 4a.

The protruding portion molding surface 4b forms the protruding portion 54b of the molded product 54. The protruding portion molding surface 4b is formed at three locations in correspondence with the number and arrangement of the protruding portions 54b. The shape of the protruding portion molding surface 4b corresponds to the outer shape of the protruding portion 54b. Specifically, the shape of the protrusion forming surface 4b is a square groove having a width w1 in the Z direction and a depth h1 from the protrusion forming surface 4b.
The protrusion forming surface 4b extends in a semicircular shape in a plane parallel to the XY plane. The groove bottom surface of the protrusion molding surface 4b is a cylindrical surface having a radius D+t+h1 from the central axis OA.

The flange portion molding surface 4c forms the flange portion 54c of the molded product 54. The flange portion molding surface 4c is formed at two locations corresponding to the number and arrangement of the flange portions 54c. The shape of the flange molding surface 4c corresponds to the outer shape of the flange 54c. Specifically, the shape of the flange molding surface 4c is a square groove having a width w2 in the Z direction and a depth h2 from the projection molding surface 4b.
The flange portion molding surface 4c extends in a semicircular shape in a plane parallel to the XY plane. The groove bottom surface of the flange portion molding surface 4c is a cylindrical surface whose radius from the central axis OA is D+t+h2.

As shown in FIG. 1, the core 1C is a columnar member having a cylindrical outer peripheral surface 1d. The core 1C forms the shape of the inner peripheral surface 54e of the molded product 54.
The outer diameter of the outer peripheral surface 1d of the core 1C is D corresponding to the outer diameter of the inner peripheral surface 54e. The length of the core 1C is L corresponding to the length of the tubular portion 54a.
The end faces 1e, 1f formed at both ends in the axial direction of the core 1C are planes orthogonal to the central axis OC of the outer peripheral face 1d.

As shown in FIG. 3, also on the parting surface 1c of the second slide core 1B, with the central axis OB as the center, similar to the first slide core 1A, the cylindrical surface molding surface 4a, the projection surface 4b, and the flange portion. A molding surface 4c is formed. However, the coordinate system in FIG. 3 indicates the attitude of the first slide core 1A.
When the parting surfaces 1c of the first slide core 1A and the second slide core 1B come into contact with each other when the injection molding die 1 is closed, the central axes OA and OB are arranged coaxially. At this time, the cylindrical molding surfaces 4a, the protrusion molding surfaces 4b, and the flange molding surfaces 4c that face each other in the Y direction form the shape of the outer peripheral surface of the molded product 54.
As shown by the chain double-dashed line, the core 1C is inserted in the Z direction at the center of the internal space surrounded by the cylindrical surface 4a. The end faces 1e and 1f of the core 1C are flush with the first end face 1a and the second end face 1b of the first slide core 1A and the second slide core 1B, respectively.
As a result, a molding space S surrounded by the outer peripheral surface 1d of the core 1C, each cylindrical portion molding surface 4a, each projection portion molding surface 4b, and each flange portion molding surface 4c is formed.

The first resin flow path portion P1 and the second resin flow path portion P2 have plane-symmetric shapes with respect to a plane that passes through the central axis OA and that is parallel to the YZ plane. Below, it demonstrates centering around the shape of the 1st resin flow path part P1.

The first resin flow path portion P1 includes a runner groove 2A and gate grooves 3A and 3B.
The runner groove 2A is a semicircular groove extending from the first end surface 1a in parallel with the central axis OA. The groove radius of the runner groove 2A is constant.
An injection port 2a is formed at the end of the runner groove 2A on the first end face 1a. The inlet 2a is a semicircular opening provided for the purpose of injecting the injection resin M into the runner groove 2A.
The runner groove 2A is extended to a length such that it can face the protrusion forming surfaces 4b and the flange forming surfaces 4c arranged in the Z direction in the X direction. Therefore, the end portion 2b of the runner groove 2A opposite to the injection port 2a is located closer to the second end surface 1b than the protrusion forming surface 4b closest to the second end surface 1b. The end 2b closes the runner groove 2A in the Z direction.
The inner diameter of the runner groove 2A is set to an appropriate size so that the molten injection resin M can flow well.

The gate groove 3A communicates the protrusion forming surface 4b with the runner groove 2A that faces the protrusion forming surface 4b in the X direction. The gate groove 3A faces the protrusion forming surface 4b in the X direction. The gate groove 3A diverts the injection resin M flowing in the Z direction in the runner groove 2A toward the protrusion molding surface 4b. For example, the gate groove 3A has a shape obtained by dividing the shape of the pin gate in half from the center. Although not shown in FIG. 3, an appropriate land shape for optimizing the speed of the injection resin M entering the molding space S is formed at the tip end portion 3a of the gate groove 3A opening on the protrusion molding surface 4b. ..

The gate groove 3B communicates the flange molding surface 4c with the runner groove 2A facing the flange molding surface 4c in the X direction. The gate groove 3B diverts the injection resin M flowing in the Z direction in the runner groove 2A toward the flange portion molding surface 4c. For example, the gate groove 3B has a shape obtained by dividing the shape of the pin gate in half from the center. Although not shown in FIG. 3, an appropriate land shape for optimizing the speed of the injection resin M entering the molding space S is formed at the tip portion 3b of the gate groove 3B opening to the flange molding surface 4c. ..

On the parting surface 1c of the second slide core 1B, the same first resin flow path portion P1 and second resin flow path portion P2 as in the first slide core 1A are formed.
When the parting surfaces 1c of the first slide core 1A and the second slide core 1B come into contact with each other when the injection molding die 1 is closed, the first resin flow path portions P1 and the second resin flow path portions P1 facing each other in the Y direction. The resin flow path portion P2 forms resin flow paths F1 and F2 each having a circular flow path cross section.
The resin flow paths F1 and F2 include a runner RA and gates GA and GB, respectively.
The runner RA is a flow path formed by a combination of the runner grooves 2A facing each other in the Y direction.
The gate GA is a flow path formed by a combination of the gate grooves 3A facing each other in the Y direction. The gate GB is a flow path formed by a combination of the gate grooves 3B facing each other in the Y direction.

A manufacturing process of the molded product 54 using the injection molding die 1 will be described.
When manufacturing the molded product 54, the injection mold 1 is attached to an injection molding machine (not shown). When the injection molding die 1 is closed, the molding space S is formed inside the assembly including the first slide core 1A, the second slide core 1B, and the core 1C, and the projection molding surface 4b is formed in the molding space S. , Resin flow paths F1 and F2 communicating with each other through the flange portion molding surface 4c are formed.
Each injection port 2a in the first end face 1a of the resin flow paths F1 and F2 communicates with a sprue (not shown) in a cavity template (not shown).
The injection resin M injected in a molten state from the injection molding machine is injected into the resin flow paths F1 and F2 through the sprue and the injection ports 2a. The injection amount of the injection resin M is predetermined according to the total volume of the molding space S and the resin flow paths F1 and F2.

The injection resin M injected from the injection port 2a of the resin flow path F1 flows in the runner RA toward the end 2b. A part of the injection resin M is branched into the gates GA and GB through the communication holes with the gates GA and GB, respectively. However, since the flow passage cross section of the gates GA and GB is smaller than the flow passage cross section of the runner RA, a large amount of the injection resin M flows out of each gate GA, GB into the molding space S because the injection resin M is inside the runner RA. After being filled.
When each runner RA is filled with the injection resin M, the injection resin M is substantially evenly filled into the molding space S from the gates GA and GB according to the injection pressure of the injection molding machine.

Since the gate GA is open to the protrusion molding surface 4b and the gate GB is opened to the flange molding surface 4c, the injection resin M is injected into the molding space S from the protrusion molding surface 4b and the flange molding surface 4c. To be filled. Specifically, the injection resin M is filled in the molding space S at a portion sandwiched by the protrusion 54b, the flange 54c, and the outer peripheral surface 1d of the core 1C.
After that, the injection resin M is branched in the Z direction, and is filled in the molding space S at a portion sandwiched between the cylindrical portion molding surface 4a and the outer peripheral surface of the core 1C. In the injection resin M flowing in the Z direction, the front end surfaces in the flow direction are in close contact with each other at the intermediate portion in the Z direction between the protrusion molding surface 4b and the flange molding surface 4c that are adjacent to each other. This completes the filling of the injection resin M in the entire molding space S.

The injection resin M filled in the molding space S is cooled by heat conduction to the first slide core 1A, the second slide core 1B, and the core 1C. When the injection resin M is left for a time such that the temperature of the injection resin M becomes equal to or lower than the glass transition point, a molded body 50 in which the injection resin M in the injection molding die 1 is solidified is formed as shown in FIG. Thereafter, the mold opening of the injection molding die 1 is executed.

When the injection mold 1 is opened, the first slide core 1A and the second slide core 1B are separated from each other in the Y direction. This allows the molded body 50 to be released from the mold.
The molded body 50 includes a molded product 54 and flow path resin portions Q1 and Q2.
The flow path resin portion Q1 is formed by solidifying the injection resin M filled in the resin flow path F1. The flow path resin portion Q1 includes a runner resin portion 52A and gate resin portions 53A and 53B to which the shapes of the runner RA and the gates GA and GB are transferred.
The flow path resin portion Q2 is formed by solidifying the injection resin M filled in the resin flow path F2. The flow channel resin portion Q2 is composed of a runner resin portion 52A and gate resin portions 53A and 53B, like the flow channel resin portion Q1.
The molded article 54 is manufactured by separating the flow path resin portions Q1 and Q2 from the molded body 50.

According to the injection molding die 1, the gates GA and GB are respectively formed on the projection 54b forming the first thick portion of the molded product 54, the projection molding surface 4b molding the flange 54c, and the flange molding surface 4c. It has an opening.
As a result, the injection resin M is filled from the molding space S corresponding to the first thick portion of the molded product 54. In this case, in the molding space S, the injection resin M moves from a space having a small flow resistance corresponding to the first thick portion to a space having a large flow resistance corresponding to a thinner tubular portion. Flowing. As a result, turbulent flow is unlikely to occur at the tip end surface of the injection resin M in the flow direction.
Furthermore, since the injection resin M is first filled in the space corresponding to the first thick portion where filling shortage is likely to occur, it is possible to prevent the shortage of the filling amount in the first thick portion.
Since a plurality of gates GA and GB are provided along the longitudinal direction of the molding space S, compared to the case where a gate is provided at the axial end of the molding space S, the injection resin M filled from one gate is filled. Has a shorter flow length. As a result, the temperature drop of the injection resin M at the tip portion in the flow direction becomes smaller, so that the filling of the injection resin M can be completed while the viscosity of the injection resin M is low. This improves the dimensional accuracy of the molded product 54.

As described above, according to the injection molding die 1, it is possible to accurately form a long tubular molded product including a thick portion.

[Second Embodiment]
An injection molding die according to the second embodiment of the present invention will be described.
FIG. 4 is a schematic perspective view of a molded product manufactured by the injection molding die according to the second embodiment of the present invention. FIG. 5 is a schematic perspective view showing an example of an injection molding die according to the second embodiment of the present invention.

First, a molded product manufactured by the injection mold of the present embodiment will be described.
As shown in FIG. 4, the molded product 64 includes a plurality of axial fins 64a (first thick part) in place of the protrusion 54b and the flange 54c of the molded product 54 according to the first embodiment. However, FIG. 4 shows the shape of the end of the molded product 64 in the axial direction. The shape of the end portion on the opposite side in the axial direction is the same as that in FIG.
Hereinafter, the points different from the first embodiment will be mainly described.

Each axial fin 64a has a flat plate shape that radially projects from the outer peripheral surface 54d of the tubular portion 54a and extends in the axial direction. The number of axial fins 64a is not particularly limited. In the example shown in FIG. 4, there are four axial fins 64a. Each axial fin 64a is provided at a position that divides the outer circumference of the outer circumferential surface 54d into four equal parts. The thickness of each axial fin 64a is w3 (however, w3>t), and the height from the outer peripheral surface 54d is h3 (however, h3>w3).
The longitudinal end of each axial fin 64a is separated from the end of the tubular portion 54a by a distance d. The length of each axial fin 64a is L-2×d.
The shape of the axial fins 64a is not an undercut shape even when the drawing direction is the axial direction of the molded product 64, but when the tubular portion 54a is long, the thickness w3 is not constant due to the draft, It is more preferable to perform molding using an injection molding die including a slide core.

As shown by the chain double-dashed line in FIG. 4, the injection molding die 11 includes a first slide core 11A instead of the first slide core 1A and the second slide core 1B in the injection molding die 1 of the first embodiment. (Slide core), second slide core 11B (slide core), third ride core 11C (slide core), and fourth slide core 11D (slide core).
The first slide core 11A, the second slide core 11B, the third ride core 11C, and the fourth slide core 11D are formed by dividing the shape of the outer peripheral portion of the molded product 64 into four equal parts along the center plane of each axial fin 64a. Has a molding surface corresponding to. Therefore, as shown in FIG. 5, the first slide core 11A, the second slide core 11B, the third ride core 11C, and the fourth slide core 11D have the same shape. However, the coordinate system of FIG. 5 shows the attitude of the first slide core 11A.

As shown by the chain double-dashed line in FIG. 4, the first slide core 11A and the second slide core 11B face each other in the Y direction. The first slide core 11A and the fourth slide core 11D face each other in the X direction. The third ride core 11C faces the second slide core 11B in the X direction and faces the fourth slide core 11D in the Y direction.
Hereinafter, the shape of the first slide core 11A will be described focusing on the points different from the first slide core 1A in the first embodiment.

As shown in FIG. 5, the outer shape of the first slide core 11A is a substantially rectangular parallelepiped elongated in the Z direction. A first end surface 1a and a second end surface 1b similar to those of the first slide core 1A are formed on the Z-direction end of the first slide core 11A. However, since FIG. 5 illustrates the end portion including the first end surface 1a in the first slide core 1A, the second end surface 1b is not shown.
On the surface of the first slide core 11A facing the second slide core 11B, a parting surface 11c formed of a plane parallel to the XZ plane is formed. On the surface of the first slide core 11A facing the fourth slide core 11D, parting surfaces 11d each formed of a plane parallel to the YZ plane are formed.

On the parting surfaces 11c and 11d, when the injection molding die 11 is closed, a molding space corresponding to a quarter of the outer shape of the molded product 64 and a molding space are formed between the molding surface and the core 1C. A resin flow path filled with the resin for use is formed, and a recess forming the resin flow path is formed.
The concave portion forming the molding space includes a cylindrical portion molding surface 14a (first molding surface) and a fin portion molding surface 14b (second molding surface). Here, the cylindrical portion molding surface 14a is formed so as to straddle the parting surfaces 11c and 11d. The fin portion molding surface 14b is formed on each of the parting surfaces 11c and 11d.
The concave portion that forms the resin flow path includes a first resin flow path portion P11 formed on the parting surface 11c and a second resin flow path portion P12 formed on the parting surface 11d.

The cylindrical portion molding surface 14a forms the shape of a quarter of the outer peripheral surface 54d excluding the axial fins 64a. The cylindrical portion molding surface 14a is a groove (hereinafter referred to as a quadrant groove) having a quadrant cross section centered on the central axis O11 and extending in the Z direction. The central axis O11 extends parallel to the Z axis at a position where the extension surfaces of the parting surfaces 11c and 11d intersect each other.
The radius of the cylindrical portion molding surface 14a is D/2. The cylindrical portion molding surface 14a penetrates between the first end surface 1a and the second end surface 1b (not shown) in the Z direction. The length of the cylindrical portion molding surface 14a is equal to the total length L of the molded product 64.

The fin portion molding surface 14b forms the outer shape of the axial fin 64a in the molded product 64.
The fin portion molding surface 14b of the parting surface 11c is formed at the intersection of the parting surface 11d and the cylindrical portion molding surface 14a. The shape of the fin portion molding surface 14b corresponds to half of the outer shape of the axial fin 64a in the thickness direction. Specifically, the shape of the fin portion molding surface 14b is such that the length in the Z direction is L-2×d, the width in the X direction is h3, and the depth in the Y direction is w3/2.
The fin portion forming surface 14b of the parting surface 11d is a recess similar to the fin portion forming surface 14b of the parting surface 11c, except that it is formed at the intersection of the parting surface 11d and the cylindrical portion forming surface 14a. ..

The first resin flow path portion P11 includes a runner groove 2A and a gate groove 13C.
The runner groove 2A is a semicircular groove similar to the runner groove 2A in the first embodiment.
However, the runner grooves 2A in the present embodiment are formed on the parting surfaces 11c and 11d, respectively, and extend parallel to the central axis O11. The length of the runner groove 2A in this embodiment is longer than L-d and shorter than L.

The gate groove 13C is a recessed portion that constitutes half of a gate shape such as a pin gate, similar to the gate groove 3A in the first embodiment. However, the gate groove 13C communicates the fin portion molding surface 14b with the runner groove 2A facing the fin portion molding surface 14b in the X direction. The gate groove 13C faces the fin portion molding surface 14b in the X direction. The gate groove 13C diverts the injection resin M flowing in the Z direction in the runner groove 2A toward the fin portion molding surface 14b.
A plurality of gate grooves 13C are arranged at equal pitches in the Z direction. The number of gate grooves 13C is not particularly limited.

The second resin flow path portion P12 on the parting surface 11d is formed on the parting surface 11d and communicates with the cylindrical portion molding surface 14a on the parting surface 11d, except for the first resin flow portion on the parting surface 11c. It is a recess similar to the road portion P11.

With such a configuration, a molding space corresponding to a quarter of the molded product 64 is formed between the outer peripheral surface 1d of the core 1C and the cylindrical portion molding surface 14a and the fin portion molding surface 14b. ..
For example, when the injection molding die 11 is closed and the parting surface 11c of the first slide core 11A and the parting surface 11d of the second slide core 11B come into contact with each other, the first resin of the first slide core 11A The flow passage portion P11 and the second resin flow passage portion P12 of the second slide core 11B form a resin flow passage having a circular flow passage cross section. This resin flow path includes a runner RA and a gate GC.
The runner RA is a flow path formed by a combination of the runner grooves 2A facing each other in the Y direction.
The gate GC is a flow path formed by a combination of the gate grooves 13C facing each other in the Y direction.

According to the injection molding die 11, the injection resin M injected from the injection port 2a is diverted from the runner RA to each gate GC, and then the thick portion sandwiched between the fin molding surface 14b and the outer peripheral surface 1d. Is filled in the molding space corresponding to. Thereafter, the injection resin M is filled in the molding space having a larger flow path resistance, which is sandwiched between the cylindrical molding surface 14a and the outer peripheral surface 1d. As a result, the molded product 64 is manufactured.
However, since the injection molding die 11 slides in four directions, the first slide core 11A, the second slide core 11B, the third ride core 11C, and the fourth slide core 11D are injected at the time of mold opening. The molding die 11 is slid in a diagonal direction (direction inclined by 45° with respect to the X axis and the Y axis).
The injection resin M is quickly filled in the molding space corresponding to the thick portion, and is filled in the molding space corresponding to the tubular portion with a small temperature decrease. Further, since a plurality of gates GC are formed in the axial direction of the molding space, the flow length of the injection resin M becomes shorter than that in the case where the gate is provided at the end portion in the axial direction.
According to the injection molding die 11 of the present embodiment, as in the first embodiment, it is possible to accurately form a long tubular molded product including a thick portion.

[Third Embodiment]
An injection molding die according to the third embodiment of the present invention will be described.
FIG. 6 is a schematic perspective view of a molded product manufactured by the injection molding die according to the third embodiment of the present invention. FIG. 7 is a schematic perspective view showing an example of an injection molding die according to the third embodiment of the present invention.

First, a molded product manufactured by the injection mold of the present embodiment will be described.
As shown in FIG. 6, the molded product 74 includes a plurality of dot-shaped projections 74a (first thick portions) instead of the axial fins 64a of the molded product 64 in the second embodiment. The molded product 74 further includes a plurality of dot-shaped protrusions 74b (second thick portion). However, FIG. 6 shows the shape of the end portion in the axial direction of the molded product 74. The shape of the end on the opposite side in the axial direction is the same as in FIG. Hereinafter, the points different from the second embodiment will be mainly described.

Each dot-shaped protrusion 74a radially projects from the outer peripheral surface 54d of the tubular portion 54a at the same circumferential position as the axial fin 64a in the second embodiment. The shape of each dot-shaped protrusion 74a viewed from the radial direction is a circle having a diameter w4 (where w4>t). The protrusion height of the dot-shaped protrusion 74a is h4 (where t<h4<w4).
The number of dot-shaped protrusions 74a is not particularly limited. The dot-shaped protrusions 74a are arranged apart from each other in the Z direction. The arrangement interval of the dot-shaped protrusions 74a is a constant value La.

Each dot-shaped protrusion 74b radially protrudes from the outer peripheral surface 54d of the tubular portion 54a at a position different from each dot-shaped protrusion 74a in the circumferential direction. In the example shown in FIG. 6, the dot-shaped protrusions 74b are arranged on a straight line extending in the axial direction in the middle of the dot-shaped protrusions 74a adjacent to each other in the circumferential direction. A plurality of dot-shaped protrusions 74b are provided so as to be separated from each other in the axial direction. The arrangement interval of the dot-shaped protrusions 74b in the axial direction is a constant value Lb. In the example shown in FIG. 6, Lb is equal to La.
Although not shown in FIG. 6, the dot-shaped protrusions 74b are similarly arranged at other positions that divide the outer peripheral surface 54d into four equal parts in the circumferential direction.
The shape of the dot-shaped protrusion 74b may be different from that of the dot-shaped protrusion 74a, but in the example shown in FIG. 6, it is the same as the shape of the dot-shaped protrusion 74a. The dot-shaped protrusions 74b may or may not be adjacent to the dot-shaped protrusions 74a in the circumferential direction. In the example shown in FIG. 6, the position of the dot-shaped protrusion 74b is axially displaced with respect to the dot-shaped protrusion 74a.

The molded product 74 is manufactured by the injection mold 21 of the present embodiment shown by the chain double-dashed line in FIG.
The injection molding die 21 is a first slide core instead of the first slide core 11A, the second slide core 11B, the third ride core 11C, and the fourth slide core 11D in the injection molding die 11 of the second embodiment. 21A (slide core), 2nd slide core 21B (slide core), 3rd ride core 21C (slide core), and 4th slide core 21D (slide core) are provided.
As shown in FIG. 7, the first slide core 21A, the second slide core 21B, the third ride core 21C, and the fourth slide core 21D have the same shape. However, the coordinate system of FIG. 7 shows the attitude of the first slide core 21A.
Hereinafter, the shape of the first slide core 21A will be described focusing on the points different from those of the first slide core 11A in the second embodiment.

The first slide core 21A includes a projection molding surface 24a (second molding surface) and a gate groove 23D instead of the fin molding surface 14b and the gate groove 13C of the first slide core 11A in the second embodiment. The first slide core 21A further includes a protrusion molding surface 24b (third molding surface). However, the runner groove 2A in this embodiment has a different length from the runner groove 2A in the second embodiment.

The protruding portion molding surface 24 a forms the outer shape of the dot-shaped protrusion 74 a in the molded product 74.
The protruding portion molding surface 24a of the parting surface 11c is formed at the intersection of the parting surface 11d and the cylindrical portion molding surface 14a. The shape of the protrusion molding surface 24a corresponds to half of the outer shape of the dot-shaped protrusion 74a in the thickness direction. Specifically, the shape of the projection molding surface 24a is a semicircular groove having a depth h4 in the X direction. The radius of the groove bottom of the protrusion molding surface 24a is W4/2. The respective projecting portion molding surfaces 24b are formed at equal intervals in the Z direction at the disposition intervals La, corresponding to the disposition positions of the dot-shaped protrusions 74a.
The projection forming surface 24a on the parting surface 11d is a recess similar to the projection forming surface 24a on the parting surface 11c except that it is formed at the intersection of the parting surface 11d and the cylindrical forming surface 14a. ..

The protrusion molding surface 24 b forms the outer shape of the dot-shaped protrusion 74 b in the molded product 74. The respective projecting portion molding surfaces 24b are formed at equal intervals in the Z direction at disposition intervals Lb corresponding to the disposition positions of the dot-shaped protrusions 74b. Each protrusion molding surface 24b is a circular hole formed in the cylindrical molding surface 14a. The projection molding surface 24b has a diameter w4 and a depth h4.

The gate groove 23D is a recess similar to the gate groove 13C in the second embodiment, except that the gate groove 23D is opened in each protrusion forming surface 24a. For example, the gate grooves 23D arranged on the parting surface 11c are arranged in one row in the Z direction at the same arrangement interval as that of the protrusion forming surface 24a. Each runner groove 2A on the parting surface 11c in the present embodiment extends in the Z direction along the row of each protrusion forming surface 24a by a length that can face each protrusion forming surface 24a.

The runner groove 2A and each gate groove 23D on the parting surface 11c form a first resin flow path portion P21. The runner groove 2A and each gate groove 23D on the parting surface 11d form a second resin flow path portion P22.

With such a configuration, a molding space corresponding to a quarter of the molded product 74 is formed between the outer peripheral surface 1d of the core 1C and the cylindrical portion molding surface 14a and the protrusion molding surfaces 24a and 24b. To be done.
When the injection molding die 21 is closed, the first resin flow passage portion P21 and the second resin flow passage portion P22 form a resin flow passage having a circular flow passage cross section similar to that of the second embodiment. This resin flow path includes a runner RA and a gate GD. Here, the gate GD is a flow path formed by a combination of the gate grooves 23D facing each other in the adjacent slide cores.

According to the injection molding die 21, the injection resin M injected from the injection port 2a is shunted from the runner RA to each gate GD, and then the thick portion sandwiched between the projection molding surface 24a and the outer peripheral surface 1d. Is filled in the molding space corresponding to. Thereafter, the injection resin M is filled in the molding space having a larger flow path resistance, which is sandwiched between the cylindrical molding surface 14a and the outer peripheral surface 1d. As a result, the molded product 74 is manufactured.
In the present embodiment, the injection resin M has a small flow path resistance in the molding space sandwiched between the protrusion molding surface 24b and the outer peripheral surface 1d. However, since the injection resin M is substantially laminar in the molding space that faces the cylindrical molding surface 14a surrounding the projection molding surface 24b, the injection resin M locally passes through the projection molding surface 24b due to the passage of the projection molding surface 24b. Even if such disturbance occurs, it does not affect the dimensional accuracy.
This embodiment is an example in which the gate may not be provided on the molding surface for molding the thick portion, depending on the area, thickness, arrangement position, number of the thick portions, and the like. In the injection-molding die 21 of the present embodiment, the thick part of the molded product 74 is composed of the first thick part and the second thick part, and the gate is formed on the second molding surface for molding the first thick part. Is provided, and the gate is not provided on the third molding surface for molding the second thick portion.
In the case of the present embodiment, since the gate is not provided on the protrusion molding surface 24b, the number of divisions of the slide core is further reduced as compared with the case where the gate is provided. According to this embodiment, the mold structure can be further simplified in the case of having various thick portions.

According to the injection molding die 21 of the present embodiment, as in the first embodiment, it is possible to accurately form a long tubular molded product including a thick portion.

[Fourth Embodiment]
An injection molding die according to the fourth embodiment of the present invention will be described.
FIG. 8 is a schematic sectional view of a molded product manufactured by the injection molding die according to the fourth embodiment of the present invention. FIG. 9 is a schematic perspective view showing an example of an injection molding die according to the fourth embodiment of the present invention.

First, a molded product manufactured by the injection mold of the present embodiment will be described.
As shown in the axial cross section in FIG. 8, the molded product 84 includes a screw 84a (first thick portion) instead of the axial fin 64a of the molded product 64 in the second embodiment. The molded product 84 further includes an outer peripheral protrusion 84b (first thick portion) and an inner peripheral protrusion 84c (second thick portion).
Hereinafter, the points different from the second embodiment will be mainly described.

The screw 84a is a single spiral protrusion that circulates on the outer peripheral surface 54d of the tubular portion 54a. The cross-sectional shape of the screw 84a in the cross section including the central axis O is not particularly limited. For example, the cross-sectional shape of the screw 84a may be a rectangular shape, an inverted U shape having a rounded tip, a trapezoidal shape, a triangular shape, a semicircular shape, or the like. In the example shown in FIG. 8, the cross-sectional shape of the screw 84a is an inverted U shape. The pitch of the screw 84a is not particularly limited. However, the screws 84a are formed with two pitches or more over substantially the entire outer peripheral surface 54d in the axial direction.
In the example shown in FIG. 8, the thickness of the screw 84a is w5 (however, w5>t), and the protrusion height is h5 (however, h5>W5). The tip of the screw 84a is rounded with a radius w5/2.

The end thick part 84b is formed on the entire circumference of both ends of the tubular part 54a in the axial direction. Each outer peripheral projection 84b projects outward from the outer peripheral surface 54d. In the example shown in FIG. 8, the protrusion height of each outer peripheral projection portion 84b from the outer peripheral surface 54d is h6 (where t<h6<h5), and the axial length of the tubular portion 54a is w6 (where w6> w5).
The inner peripheral protrusions 84c are formed on the entire circumference of both ends of the tubular portion 54a in the axial direction. Each inner peripheral protruding portion 84c projects inward from the inner peripheral surface 54e. In the example shown in FIG. 8, the height of each inner peripheral protruding portion 84c from the inner peripheral surface 54e is h7 (however, h7>t), and the axial length is w7 (however, t<w7<w5). .. However, the height h7 is set to a size that allows forcible removal according to the rigidity of the material of the molded product 74.

The molded product 84 is manufactured by the injection molding die of this embodiment including a core and four slide cores, as in the second embodiment.
In FIG. 9, the first slide core 31A and the fourth slide core 31D that form a part of the injection molding die 31 of the present embodiment are shown by solid lines, and the core 31E is shown by chain double-dashed lines. The second slide core and the third slide core (not shown) have the same shape as the first slide core 31A except for the arrangement of the second molding surface and the gate groove, which will be described later.
Hereinafter, the shapes of the first slide core 31A and the fourth slide core 31D will be described focusing on the points different from the first slide core 11A in the second embodiment.

The first slide core 31A replaces the fin portion molding surface 14b and the gate groove 13C of the first slide core 11A in the second embodiment, and instead of the screw molding surface 34a (second molding surface), the protrusion molding surface 34c (first 2 molding surface) and gate grooves 33E and 33F. However, the runner groove 2A in this embodiment has a different length from the runner groove 2A in the second embodiment.

The screw molding surface 34 a forms the outer shape of a quarter of the screw 84 a in the molded product 84. The screw molding surface 34a is a U-shaped groove that extends in a spiral shape and is formed over the parting surfaces 11c and 11d.
The opening width and depth of the screw molding surface 34a are w5 and h5, respectively, corresponding to the shape of the screw 84a. The groove bottom surface 34g (tip end surface) of the screw molding surface 34a is rounded to a radius w5/2.
Although not shown in FIG. 9, a plurality of screw molding surfaces 34a are formed according to the number of turns of the screw 84a. The arrangement interval of the screw molding surfaces 34a is equal to the pitch of the screws 84a.

The protrusion molding surface 34c has a length w6 in the Z direction and a depth h6 from the cylindrical portion molding surface 14a of the outer shape of the outer peripheral protrusion 84b of the molded product 84.

The gate groove 33E is a recess that communicates with the screw molding surface 34a and the runner groove 2A. The gate grooves 33E are formed on the parting surfaces 11c and 11d in the same number as the screw molding surfaces 34a. Each gate groove 33E is a semicircular groove similar to the gate groove 13C in the second embodiment. However, in the present embodiment, each gate groove 33E is formed in an L shape between the runner groove 2A and the screw molding surface 34a.
The tip portion 33a of each gate groove 33E is open to one of the Z-direction inner side surfaces of the screw molding surface 34a. In the example shown in FIG. 9, the tip portion 33a is opened to the inner side surface 34e on the right side in the drawing, but may be opened to the inner side surface 34f on the left side in the drawing.
The position of the tip portion 33a in the X direction is not particularly limited. In the example shown in FIG. 9, the tip portion 33a is hg (where 0<hg<h5/2) measured in the depth direction of the screw molding surface 34a. In this case, the gate groove 33E opens at a position closer to the cylindrical portion molding surface 14a than the groove bottom of the screw molding surface 34a.

The gate groove 33F is a recess similar to the gate groove 13C in the second embodiment, except that the gate groove 33F is opened in each projection forming surface 34c. The gate groove 33F is formed in each of the parting surfaces 11c and 11d.

The core 31E is configured in the same manner as the core 1C, except that the projection molding surface 31d (second molding surface) that forms the outer shape of the inner circumferential projection 84c is formed at both ends in the axial direction. ..
The protruding portion molding surface 31d is a step portion formed around the entire circumference with a width w7 and a depth h7.

The runner groove 2A and the gate grooves 33E and 33F on the parting surface 11c constitute a first resin flow path portion P31. As shown in an example of the parting surface 11d of the fourth slide core 31D described later in FIG. 9, the runner groove 2A and the gate grooves 33E and 33F of the parting surface 11d constitute the second resin flow path portion P32. There is.

With such a configuration, the outer peripheral surface 1d of the core 31E, the cylindrical portion molding surface 14a, the screw molding surfaces 34a, the protrusion molding surfaces 34c and 24b, and the protrusion molding surface 31d of the core 31E. A molding space corresponding to a quarter of the molded product 84 is formed between the protruding part molding surface 34c.

The fourth slide core 31D includes a screw molding surface 34d (second molding surface) instead of the screw molding surface 34a of the first slide core 31A.
The screw molding surface 34d molds a screw 84a for a quarter turn following the screw 84a for a quarter turn of the screw 84a molded on the screw molding surface 34a. In the parting surfaces 11c and 11d facing each other in the X direction, the opening of the screw molding surface 34d coincides with the opening of the screw molding surface 34a. The position of the screw molding surface 34d in the Z direction is shifted to the left side in the drawing by a quarter pitch of the screw 84a with respect to the screw molding surface 34a.

The gate groove 33E in the fourth slide core 31D is formed in the same manner as the gate groove 33E in the first slide core 31A, except that the tip portion 33a is open to the inner surface of the screw molding surface 34d in the Z direction. In the example shown in FIG. 9, the tip portion 33a is opened on the inner side surface 34f on the left side in the drawing, but may be opened on the inner side surface 34e on the right side in the drawing.
Similar to the first slide core 31A, a first resin flow path portion P31 is formed on the parting surface 11c and a second resin flow path portion P32 is formed on the parting surface 11d.

With such a configuration, for example, when the injection molding die 31 is closed, the first resin flow path portion P31 and the second resin flow path portion P32 have a circular flow path cross section similar to that of the second embodiment. A resin flow path is formed. This resin flow path includes a runner RA and gates GE and GF. Here, the gate GE is a flow path formed by a combination of mutually facing gate grooves 33E in adjacent slide cores. The gate GF is a flow path formed by a combination of the gate grooves 33F facing each other in the slide cores adjacent to each other.

According to the injection molding die 31, the molded article 84 is manufactured in the same manner as in the second embodiment. However, in the present embodiment, the molded product 84 is forcibly removed from the core 31E.
According to the injection molding die 31 of the present embodiment, as in the second embodiment, it is possible to accurately form a long tubular molded product including a thick portion.
In particular, even in the shape in which the screw 84a that is thicker than the cylindrical portion 54a is formed on the entire circumference, the injection space M is filled from the plurality of gate grooves 33E into the molding space that forms the screw 84a. As a result, insufficient filling of the injection resin M into the screw 84a and the tubular portion 54a, reduction in dimensional accuracy, etc. are suppressed.

Further, according to the present embodiment, the tip end portion 33a of the gate groove 33E is open to the inner side surface of the screw molding surface 34a or the like. As a result, no gate mark is formed on the tip of the screw 84a in the molded product 84, so that the tip of the screw 84a is formed into a smooth curved surface.
Further, according to the present embodiment, the tip portion 33a of the gate groove 33E is opened at a position close to the cylindrical portion molding surface 14a in the protruding direction of the screw molding surface 34a and the like. As a result, the injection resin M injected from the gate groove 33E more easily flows into the molding space forming the tubular portion 54a, so that the tubular portion 54a can be more accurately shaped even if the tubular portion 54a is thin. Is formed.

[Fifth Embodiment]
An injection molding die according to the fifth embodiment of the present invention will be described.
FIG. 10: is a typical front view which shows an example of the principal part of the injection mold of the 5th Embodiment of this invention.

As shown in the main part in FIG. 10, the injection molding die 41 of the present embodiment includes a first slide core 41A instead of the first slide core 1A of the first embodiment. However, like the first slide core 1A, the first slide core 41A has a plane symmetric shape with respect to a plane parallel to the YZ plane, and therefore FIG. 10 shows a half shape of the first slide core 41A in the X direction. Has been done. In FIG. 10, the shape of a half of the molded product 84 molded by the injection molding die 41 in the X direction is shown by a chain double-dashed line.
The injection molding die 41 includes a second slide core 41B instead of the second slide core 1B in the first embodiment. The second slide core 41B has the same shape as the second slide core 1B. However, the coordinate system in FIG. 10 indicates the attitude of the first slide core 41A.
Hereinafter, the shapes of the molded product 94 and the first slide core 41A will be described focusing on the points different from those of the molded product 54 and the first slide core 1A in the first embodiment.

The molded product 94 includes four protrusions 54b instead of the three protrusions 54b and the two flanges 54c of the molded product 54. The arrangement interval of the protrusions 54b in the Z direction is L0.

The first slide core 41A has four protrusions instead of the protrusion molding surfaces 4b and the flange molding surfaces 4c of the first slide core 1A, the first resin flow channel P1 and the second resin flow channel P2. The molding surface 4b and the two resin flow path portions P41 are provided.
However, in FIG. 10, a resin flow path portion P41 corresponding to the second resin flow path portion P2 is shown. The resin flow path portion P41 corresponding to the first resin flow path portion P1 (not shown) has a shape that is plane-symmetrical to the illustrated resin flow path portion P41 with a plane that passes through the central axis OA and is parallel to the YZ plane as a plane of symmetry. Have. Hereinafter, an example of the resin flow path portion P41 shown in FIG. 10 will be described.

The protrusion forming surface 4b is formed in the same manner as the protrusion forming surface 4b in the first embodiment, except for the number and arrangement position.
The protrusion forming surface 4b in the present embodiment has four protrusions 54b spaced apart in the Z direction at the arrangement interval L0, corresponding to the arrangement interval L0 at the arrangement interval L0 on the cylindrical portion forming surface 4a. It is provided at four locations separated in the direction.
In the following, in the Z direction, a plane that bisects vertically between the cylindrical portion molding surface 4a arranged second from the first end surface 1a side and the cylindrical portion molding surface 4a arranged third is used as a reference. It is referred to as surface C. The reference plane C is a plane parallel to the XY plane.

The resin flow path portion P41 is an assembly of semicircular grooves on the parting surface 1c. The resin flow path portion P41 includes a first runner groove 42A (runner groove), a second runner groove 42B (runner groove), a third runner groove 42C (runner groove), a fourth runner groove 42D (runner groove), and a plurality of The gate groove 3A is provided.

The first runner groove 42A is a semicircular groove extending between the injection port 42a and the first opening 42b. The groove radius of the first runner groove 42A is constant. The inlet 42a is a semicircular opening that opens to the first end face 1a. The position of the inlet 42a may be the same as or different from that of the inlet 2a.
The first opening 42b is a semicircular opening centered on a straight line where the reference plane C and the parting surface 1c intersect.
The path of the first runner groove 42A is not particularly limited. In the example shown in FIG. 10, the first runner groove 42A extends in the Z direction from the injection port 42a, bends in the X direction away from the central axis OA, bends in the Z direction toward the reference plane C, and It is formed along a path that bends in the X direction toward the first opening 42b at a position facing the opening 42b.

The second runner groove 42B includes a first semicircular groove having a length of 2×L1 extending in the Z direction and a second semicircular groove having a length L2 extending from both ends of the first semicircular groove toward the central axis OA in the X direction. It consists of a semicircular groove. The groove radius of the second runner groove 42B is constant. A first opening 42b is opened at the center of the first semicircular groove in the Z direction. A second opening 42c and a third opening 42d are formed at the tip of the second semicircular groove, respectively.

The third runner groove 42C is a third semicircular groove having a length of 2×L3 (where L3=L0/2) extending in the Z direction. A gate groove 3A extending in the X direction is opened at both ends of the third semicircular groove. The second opening 42c is opened at the center of the third runner groove 42C in the Z direction.
The fourth runner groove 42D is composed of a fourth semi-circular groove having a length of 2×L3 and extending in the X direction in the Z direction. Gate grooves 3A are opened at both ends of the fourth semicircular groove. The second opening 42c is opened at the center of the third runner groove 42C in the Z direction.
The groove radii of the third runner groove 42C and the fourth runner groove 42D are constant and equal to each other.

In this way, the resin flow path portion P41 forms a branch flow path from the injection port 42a toward the four protruding portion molding surfaces 4b. When the length of the first runner groove 42A is La and the length of the gate groove 3A is Lg, the lengths of the respective branch flow paths are La+L1+L2+L3+Lg and are equal to each other.

When the injection molding die 41 is closed, the resin flow passage portion P41 of the first slide core 41A and the resin flow passage portion P41 of the second slide core 41B form a resin flow passage having a circular flow passage cross section. .. Runners R1, R2, R3, R4 and a gate GA are formed in this resin flow path.
Here, the runners R1, R2, R3, and R4 are combinations of first runner grooves 42A, second runner grooves 42B, third runner grooves 42C, and fourth runner grooves 42D that face each other in the Y direction. Is a flow path formed by.
Similar to the first embodiment, the gate GA is a flow path formed by a combination of the gate grooves 3A facing each other in the Y direction.
As described above, the lengths of the branch flow paths in the resin flow path portion P41 are equal to each other, and therefore, in the resin flow path described above, the lengths of the flow paths from the injection port 42a to the protrusion forming surfaces 4b are also equal to each other. .. As a result, the arrival times of the injection resin M injected from the injection port 42a to reach the protrusion molding surfaces 4b are equal to each other.
The runners R1, R2, R3, R4 in the resin flow path of the present embodiment constitute a flow adjustment flow path section that equalizes the arrival time of the injection resin M from the injection port 42a to each of the plurality of gate grooves 3A. There is.

According to the injection molding die 41, the molded product 94 is manufactured in the same manner as in the first embodiment.
According to the injection molding die 41 of the present embodiment, as in the first embodiment, it is possible to accurately form a long tubular molded product including a thick portion.
In particular, in the present embodiment, the resin flow path is provided with the flow adjusting flow path portion including the runners R1, R2, R3, and R4, so that the same amount of injection resin M is simultaneously filled from each gate GA. As a result, the filling balance of the injection resin M from each gate GA becomes good, and the precision of the molded product can be further improved.

In addition, in the description of each of the above-described embodiments, since the first thick portions are arranged at equal intervals, an example in which a plurality of gates are arranged at equal intervals in the axial direction has been described. However, the gates may not be arranged at equal intervals depending on the arrangement and shape of the first thick portion where the gate is open. For example, the gates may not be arranged at equal intervals depending on the arrangement and shape of the first thick portion. For example, if the gates are arranged at equal intervals, and the gates deviate from the center of the second molding surface, it may be more preferable to arrange them at the center of the second molding surface.

In the above description of the third embodiment, an example has been described in which the third molding surface is formed at a position different from the second molding surface in the circumferential direction. However, the third molding surface may be formed on the parting surface.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other changes can be made to the configuration without departing from the spirit of the present invention.
Also, the invention is not limited by the above description, but only by the appended claims.

1, 11, 21, 31, 41 Injection mold 1A, 11A, 21A, 31A, 41A 1st slide core (slide core)
1B, 11B, 21B, 41B Second slide core (slide core)
1c, 11c, 11d Parting surface 1C, 31E Core 1d, 54d Outer peripheral surface 2a, 42a Injection port 2A Runner groove 3A, 3B, 13C, 23D, 33E, 33F Gate groove 4a, 14a Cylindrical part molding surface (first molding surface)
4b, 24a, 31d, 34c Projecting part molding surface (second molding surface)
4c Flange molding surface (second molding surface)
11C, 21C 3rd slide core (slide core)
11D, 21D, 31D 4th slide core (slide core)
14b Fin part forming surface (second forming surface)
24b Projection molding surface 34a, 34d Screw molding surface 34e, 34f Inner side surface 34g Groove bottom surface (tip surface)
42A 1st runner groove (runner groove)
42B Second runner groove (runner groove)
42C 3rd runner groove (runner groove)
42D 4th runner groove (runner groove)
54, 64, 74, 84, 94 Molded product 54a Cylindrical part 54b Projection part (first thick part)
54c Flange part (first thick part)
54e Inner peripheral surface 64a Axial fin 74a Dot-shaped projection (first thick portion)
74b Dot-shaped protrusion (second thick portion)
84a screw (first thick part)
84b End thick part (first thick part)
84c Inner peripheral projection (second thick portion)
C reference planes F1, F2 resin flow paths GA, GB, GC, GD, GE, GF gate M injection resins O, O11, OA, OB, OC central axis lines P1, P11, P31 first resin flow path parts P2, P12, P32 Second resin flow path portion P41 Resin flow path portion R1, R2, R3, R4, RA Runner S molding space

Claims (7)

An injection molding die for forming a molded product, wherein the molded product has a tubular portion and a plurality of first thick portions thicker than the thickness of the tubular portion, and the plurality of first thick portions Is projected from the surface of the tubular portion, and the injection molding die is
Equipped with a plurality of slide cores that abut each other on the parting surface,
The plurality of slide cores,
A first molding surface for molding the outer peripheral surface of the molded product in a portion excluding the plurality of first thick portions;
A plurality of second molding surfaces for molding the outer peripheral surfaces of the plurality of first thick portions,
A plurality of gate grooves formed in the parting surface and opening in each of the plurality of second molding surfaces;
A runner groove formed in the parting surface, having an injection port through which injection resin is injected, and a runner groove opening in the plurality of gate grooves,
Including each,
Of the plurality of slide cores, a runner is formed by a combination of the runner grooves in adjacent slide cores, and a plurality of gates are formed by a combination of the gate grooves in adjacent slide cores,
The injection resin is divided into the plurality of gates through the runner,
Injection mold. In each of the plurality of slide cores,
The plurality of second molding surfaces are arranged apart from each other in the axial direction of the first molding surface, corresponding to the arrangement of the plurality of first thick portions,
The runner groove is
Linearly extending in the axial direction along the arrangement of the plurality of gate grooves,
The injection mold according to claim 1. The runner is
The injection resin includes a flow adjustment flow path unit that equalizes arrival times from the injection port to each of the plurality of gates,
The injection mold according to claim 1. The plurality of slide cores,
Corresponding to the fact that the molded product further comprises a second thick portion having a thickness greater than that of the tubular portion,
An outer peripheral surface of the second thick part of the molded product is molded, and further comprising a third molding surface in which the plurality of gates are not opened.
The injection mold according to claim 1. The plurality of gates are
Arranged at equal intervals in the axial direction,
The injection mold according to claim 1. The plurality of second molding surfaces,
A third molding surface including a tip surface that forms a tip in the depth direction from the first molding surface, and an inner side surface that sandwiches the tip surface in a direction intersecting the depth direction,
Of the plurality of gates, a gate opening to the third molding surface is open to the inner side surface,
The injection mold according to claim 1. The gate is
In the depth direction, the third molding surface is opened at a position closer to the first molding surface than the tip surface.
The injection mold according to claim 6.

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