JP2003025389A - Mold for injection molding cylindrical molding and method for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a quality of a molding in a mass production by reducing a damage, a deformation or the like without changing a conventional molding cycle. SOLUTION: A mold for injection molding a cylindrical molding molds the cylindrical molding in a space generated in a mold closing state of an opposed movable side mold 2 and a fixed side mold 1. The mold comprises core members 15, 16 in which outer peripheral surfaces become cylindrical when mounted and associated in the mold 2, a cavity member 4 having a hole molding surface of a circular hole-like state opposed to the outer peripheral surfaces of the members 15, 16, a clamping means 18 for clamping the mold 2 and the mold 1 at the time of initially opening the mold after a molten material is filled in the space and opening the clamping at the time of half operating after the mold is opened, a center core 14 for moving the members 15, 16 to retracting positions from the inner periphery of the molding at the time of initial operation of opening the mold, and a work holding means 17 mounted at the member 10 disposed oppositely to the member 4 so as to hold the outer periphery of the molding at the time of half operating after the mold is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die and an injection molding method for accurately molding a cylindrical molded product.

[0002]

2. Description of the Related Art For example, as an injection mold for a cylindrical molded product, an injection mold for molding a molded product having an undercut such as a helicoid screw on its inner peripheral surface is disclosed in Japanese Patent Publication No. 59-1.
It is disclosed in Japanese Patent No. 4333. This conventional technique will be described with reference to FIGS. In FIG. 16 and FIG. 17, first slide members 102 and second slide members 103 are alternately and axially provided around a core rod 101 having a pyramidal outer surface having different inclination angles on the upper side. The slide members are slidably arranged in a desired direction, and a desired helicoid-shaped undercut shape is engraved on the outer peripheral side of the upper ends of these slide members.

Next, the operation of the injection molding die having the core rod having the above-mentioned structure during injection molding will be described. At the time of injection molding work, as shown in FIG. 18, the molding die 107 is closed, the movable side die 105 and the fixed side die 106 are closed together, and a nozzle is provided in the space (cavity) between them. A molding material is injected through 109 to form an injection molded product 108. After the molding die 107 is opened after molding, that is, after the movable side die 105 and the fixed side die 106 are separated from each other and the outer peripheral surface of the injection-molded article 108 is exposed, FIG.
As shown in FIG. 9, first, the plate 152 with respect to the substrate 151,
When 153 and 154 are moved in the mold opening direction by the stroke S, the core rod 101 is fixed to the substrate 151.
The second slide member 103 and the first slide member 102 move along the conical outer surface of the core rod 101, that is, the first slide member 102 and the second slide member 103 relatively open with respect to the core rod 101. It slides in the direction and moves toward the axis of the core rod 101. This allows
From the inner peripheral portion of the injection molded product 108 to the first slide member 102
And the undercut shape of the second slide member 103 moves in the radial center direction and separates, and as shown in FIG.
When the plate 154 is raised with respect to the plate 153, the injection molded product 108 can be taken out.

As a result, it is possible to freely add a complicated undercut such as a helicoid screw or a cam groove to the inner peripheral portion, and it is not necessary to carry out a secondary process for making an undercut for an injection molded product, which is inexpensive. This means that stable production will be possible.

[0005]

However, the above-mentioned prior art has the following problems. That is, in the above-mentioned conventional technique, after molding the injection-molded product in which the undercut is formed in the inner peripheral portion by the slide members 102 and 103 arranged around the core rod 101, the movable-side mold and the fixed-side mold are separated. Is separated along the parting line to open the molding die, and then the slide members 102 and 103 are moved. At this time, in the case of injection molding using a resin material, a sufficient pressure is applied to the injection molded product during injection filling, and the resin is cooled while the pressure is maintained. The injection-molded product tries to shrink in volume by cooling, but it cannot shrink because the core member such as the core rod, the first slide member, and the second slide member exists in the center part, and the injection-molded product is fixed by molding the outer peripheral part. State that the inner peripheral surface of the side mold is strongly pressed (that is,
It is in a state where internal strain has occurred in the injection molded product). Therefore, if the mold is opened as it is, the inner peripheral surface of the mold that forms the outer peripheral portion of the injection-molded product causes so-called "peeling" such as scratches and deformation on the outer peripheral part of the injection-molded product. There is a problem that the appearance quality is impaired.

Further, if the pressure setting on the injection molding machine side given to the molded product is made small in order to prevent the occurrence of such "stripped", the problem of "stripped" is reduced, but it cannot be completely solved. Also, if the pressure setting on the injection molding machine side is set too low, "sink" may occur in the injection molded product,
Anisotropy of molding shrinkage occurs, which deteriorates shape accuracy such as roundness and cylindricity, which is also a cause of quality variation in mass production. In addition, the problem of "take-off" can be reduced by extending the cooling time of the injection-molded product in the molding die, but it cannot be completely solved in the same manner, and the productivity is significantly increased by extending the molding cycle. It was an obstacle.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the invention according to claim 1, 2, 3 or 4 is to provide a scratch or a deformation without changing the conventional molding cycle. It is to provide an injection molding die for a cylindrical molded product, which can reduce the manufacturing cost and stabilize the quality in mass production.

An object of the present invention according to claim 5 or 6 is to provide an injection molding method for a cylindrical molded article, which comprises injection molding a molding material using the injection molding die according to claim 1, 2, 3 or 4. That is.

[0009]

[Means for Solving the Problems]

In order to solve the above-mentioned problems, claim 1
The invention according to 2, 3, or 4 is an injection molding die for molding a cylindrical molded product by a space portion generated in a mold closed state in which the parting surfaces of the movable side mold and the fixed side mold facing each other are brought into contact with each other. A core member which is attached to the movable side mold so as to mold the inner peripheral part of the cylindrical molded product and has an outer peripheral surface which is cylindrical when combined with each other;
A cavity that is used as a component of the movable side mold or the fixed side mold so as to mold the outer peripheral portion of the cylindrical molded product, and that has a circular hole-shaped molding surface that faces the outer peripheral surface of the core member. Member, mold opening after injection filling of a molten material into the space between the outer peripheral surface of the core member and the hole forming surface of the cavity member formed in a state where the movable side mold and the fixed side mold are closed Fastening means for fastening the movable side mold and the fixed side mold during the initial operation and releasing the fastening between the movable side mold and the fixed side mold during the latter half operation of the mold opening, and during the mold opening initial operation A center core for moving the core member from the inner peripheral portion of the cylindrical molded product to a retracted position, and a slide arranged so as to face the cavity member so as to hold the outer peripheral portion of the cylindrical molded product during the latter half operation of the mold opening. Protection Comprising a workpiece holding means attached to a member.

According to a fifth aspect of the present invention, there is provided an injection molding method for molding a cylindrical molded product by a space portion generated in a mold closed state in which the parting surfaces of the movable mold and the stationary mold which are opposed to each other are brought into contact with each other. A core member which is attached to the movable side mold so as to mold the inner peripheral part of the cylindrical molded product and has a cylindrical outer peripheral surface, and the movable side metal mold so as to mold the outer peripheral part of the cylindrical molded product. A cavity member used as a component of a mold or the fixed-side mold and having a cylindrical hole forming surface facing the outer peripheral surface of the core member, and one end side of the cylindrical molded product are molded. And a slide holding member arranged to face the cavity member, the movable side mold and the fixed side mold are closed, and the parting surface is brought into contact with the mold.
The space portion is formed by the outer peripheral surface of the core member, the hole forming surface of the cavity member, and the slide holding member, and a molten material is injected and filled into the space portion, and then the contact of the parting surface is performed. After the outer peripheral surface of the core member is moved toward the axial center of the cylindrical molded product with the outer peripheral surface of the core member retracted from the inner peripheral portion of the cylindrical molded product while being fastened, the movable side mold and By releasing the fastening with the fixed side mold and separating the parting surfaces from each other, the outer peripheral portion of the cylindrical molded product is separated from the hole molding surface of the cavity member, and the cylindrical molded product does not have the cavity member. The mold opening operation is completed while holding the fixed side mold or the movable side mold, and the cylindrical molded product is taken out.

According to a sixth aspect of the present invention, in the injection molding method for a cylindrical molded product according to the fifth aspect, the mold is held while the cylindrical molded product is held in a fixed mold or a movable mold that does not have the cavity member. Instead of completing the opening operation and taking out the cylindrical molded product, the mold opening operation is completed while the cylindrical molded product is held by the work holding means attached to the slide holding member, and the cylindrical molded product is taken out.

In the injection molding die for a cylindrical molded product according to the first, second, third or fourth aspect of the present invention, the movable side mold and the fixed side mold are operated during the initial opening operation of the injection molding machine after injection molding. A direction in which the outer peripheral surface of the core member that molds the inner peripheral part of the molded product before the parting surface (parting line) does not open, separates from the inner peripheral part of the cylindrical molded product. By moving the cylindrical molded product inward in the radial direction and retracting it, the cylindrical molded product can be molded and shrunk in the axial direction, and the pressing force on the cavity member side of the outer peripheral part of the molded product is reduced. Then, in the latter half of the operation of the injection molding machine, one end side of the outer peripheral portion of the cylindrical molded product is held by the work holding means attached to the slide holding member, and most of the outer peripheral portion of the cylindrical molded product is molded. By pulling out from the hole molding surface of the cavity member, the cylindrical molded product can be easily separated from the cavity member.

In the injection-molding die for a cylindrical molded product according to the second aspect of the present invention, in addition to the above-mentioned action, the center core is formed of a core rod having a conical outer surface having different inclination angles and extending in the mold opening direction. The core member is composed of a plurality of slide members which are respectively arranged on the outer surface of the core rod and whose outer peripheral surface becomes cylindrical when combined so as to mold the inner peripheral portion of the cylindrical molded product. The slide members are configured to move toward the axial center of the core rod when the core rod moves in the mold opening direction, so that the cylindrical molded product can be uniformly molded and shrunk in the axial direction. It is possible to reduce the internal strain of the cylindrical molded product.

In the injection-molding die for a cylindrical molded product according to the third aspect of the present invention, in addition to the above-mentioned actions, the core member molds the inner peripheral portion of the cylindrical molded product, and the hole molding surface of the cavity member and the cylindrical molded product. Before the mold is opened from the outer periphery, it moves toward the center of the center core during the initial operation of the mold to separate from the inner peripheral part of the cylindrical molded product, and then in the mold opening direction relative to the inner peripheral part of the cylindrical molded product. Due to the retracted structure, the core member forming the inner peripheral portion of the cylindrical molded product moved toward the axial center of the center core before the hole molding surface of the cavity member and the outer peripheral portion of the cylindrical molded product separate from each other. After that, the core member moves in the mold opening direction relative to the inner peripheral portion of the cylindrical molded product.

In the injection-molding die for a cylindrical molded product according to the fourth aspect of the present invention, in addition to the above-mentioned action, the work holding means forms a plurality of external undercut parts which are convex or concave on the outer peripheral part of the cylindrical molded product. An external undercut part is formed on the outer peripheral part of the cylindrical molded product by holding the cylindrical molded product on the slide holding member via the external undercut part until the movable side mold starts to open the mold. The cylindrical molded product is formed and is reliably separated from the cavity member by utilizing this external undercut portion.

In the injection molding method for a cylindrical molded product according to the fifth aspect of the invention, the outer peripheral surface of the core member is cylindrically molded while the space portion is injected and filled with the molten material and the contact of the parting surface is fastened. The outer peripheral surface of the core member is retracted from the inner peripheral part of the cylindrical molded product by moving it toward the axis of the product, and then the movable side mold and the fixed side mold are released from each other's parting. The surfaces are separated, the outer peripheral part of the cylindrical molded product is separated from the hole molding surface of the cavity member, and the mold opening operation is completed while holding the cylindrical molded product in the fixed side mold or the movable side mold without the cavity member. , By taking out the cylindrical molded product, the mold release of the cylindrical molded product and each member of the injection molding die is facilitated, and the cylindrical molded product is held in the fixed side mold or the movable side mold so that it can be taken out easily. .

In the injection molding method for a cylindrical molded product according to the sixth aspect of the invention, after the molten material is injected and filled in the space, the outer peripheral surface of the core member is cylindrically molded while the contact of the parting surface is fastened. The outer peripheral surface of the core member is retracted from the inner peripheral part of the cylindrical molded product by moving it toward the axis of the product, and then the movable side mold and the fixed side mold are released from each other's parting. The surfaces are separated from each other, the outer peripheral portion of the cylindrical molded product is separated from the hole forming surface of the cavity member, and the mold opening operation is completed while the separated cylindrical molded product is held by the work holding means attached to the slide holding member. By taking out the molded product, the cylindrical molded product and each member of the injection mold are smoothly released from each other, and the cylindrical molded product is held by the work holding means so that it can be taken out easily.

[0019]

DETAILED DESCRIPTION OF THE INVENTION Specific embodiments will be described below. The molding material in the embodiment of the present invention is a resin material, a metal material, or the like, and is applicable to a material that can be melted and can be molded by solidifying after cooling.

(Embodiment 1) FIGS. 1 to 11 show Embodiment 1, FIG. 1 is a longitudinal sectional view of an injection molding die of a cylindrical molded product, FIG. 2 is a perspective view of a first slide member, and FIG. 6 is a perspective view of a core rod, FIG. 4 is a vertical cross-sectional view of a cylindrical molded product, FIG. 5 is a vertical cross-sectional view showing engagement between an angular cam and an outer slide member, and FIG.
Is a vertical cross-sectional view of the injection mold in the mold closed state, FIG. 7 is a vertical cross-sectional view of the injection mold in the first stage mold open state, and FIG. 8 is a vertical cross-sectional view of the injection mold in the second stage mold open state. FIG. 9 is a vertical cross-sectional view of the injection molding die in the third stage mold opening state, FIG. 10 is a vertical cross-sectional view of the final stage injection molding die in the mold opening state, and FIG. 11 is injection molding of the cylindrical molded product in the protruding state. It is a longitudinal cross-sectional view of a mold.

In FIG. 1, the fixed-side mold 1 has a fixed-side mold plate 4, a runner drop plate 6 and a fixed-side mounting plate 3, and support pins 36 planted in the fixed-side mounting plate 3.
A runner drop plate 6 and a fixed-side mold plate 4 are slidably fitted to a. Further, stop pins 30a and 30b having stepped heads are screwed to the runner drop plate 6 from different directions, and the fixed mold plate 4, runner drop plate 6 and fixed mounting plate 3 are not shown in the drawing. It is possible to isolate a predetermined amount in the mold opening direction of the injection molding machine. The fixed-side template 4 is an outer peripheral portion 20a of the cylindrical molded product 20 (see FIG. 4).
It has a hole forming surface 4a in the shape of a circular hole that functions as a cavity member for forming a hole. The fixed side mold plate 4 has an inner circumference of the cylindrical molded product 20 that is orthogonal to the hole forming surface 4a. The fixed core member 5 having an end molding surface that forms an end surface together with a part of the portion 20b (see FIG. 4) is the spring 3
It is movably held between the molding position and the retreat position via 2. The spring 32 is housed in a counterbore hole provided in the stationary mold plate 4 while being biased in the mold opening direction.

A spring 31 is inserted between the bottom surface of the countersunk hole formed in the stationary mold plate 4 and the runner drop plate 6 so as to pass through the stop pin 30b and urged in the mold opening direction. Further, the fixed side mounting plate 3 is provided with a sprue bush 7 which forms a resin flow path 7a from the nozzle of the molding machine and penetrates the runner drop plate 6, and the resin flow path 7a
A runner 5 a that communicates with the pinned gate 5 b that communicates with the cylindrical molded product 20 is formed in the fixed-side core member 5. Further, in order to regulate the moving amount of the fixed side core member 5 lifted by the spring 32 housed in the counterbore hole of the fixed side template 4, the fixed side template 4 is screwed with its screw portion, and the fixed side core 4 is fixed. A shaft pin passing through the member 5 and a stop pin 9 having a head at its end are provided. In addition, a runner lock pin 8 that penetrates the runner drop plate 6 and can hold the resin in the runner 5a is planted in the fixed-side mounting plate 3.

On the other hand, the movable mold 2 is composed of a stripper plate 10 facing the fixed mold plate 4, a slide holding plate 11, a core holding plate 12 and a movable mounting plate 13, and the core holding plate. In addition to the stripper plate 10 and the slide holding plate 11, the fixed-side mold plate 4 of the fixed-side mold 1 is slidably fitted to the guide pins 36b planted in 12. The core holding plate 12 and the movable side mounting plate 13 are fixed to each other, and the slide holding plate 11 has its threaded portion screwed onto the slide holding plate 11 and has penetrated the core holding plate 12 and the movable side mounting plate 13. By the limiting bolt 33 having the shaft portion and the head portion at its end, the core holding plate 12 is in contact with the core holding plate 12 in the mold opening direction of the injection molding machine in a state of being separable by a predetermined amount. Further, the stripper plate 10 has its threaded portion screwed onto the stripper plate 10, and the slide holding plate 1
1, the core holding plate 12, and the movable side mounting plate 13
When the mold is closed, it is in contact with the slide holding plate 11 in such a state that it can be slid by a predetermined amount in the mold opening direction of the injection molding machine by a protruding rod 34 having a shaft portion penetrating through and a head at its end. The length of the shaft of the limit bolt 33,
Also, the length of the shaft portion of the protruding rod 34 is set to be separated by the predetermined amount when the slide holding plate 11 and the core holding plate 12 are separated or when the stripper plate 10 and the slide holding plate 11 are separated. Is set to.

At the center of the stripper plate 10,
A pressing block 10a having inclined surfaces 15d (see FIG. 2) of the first slide member 15 and the second slide member 16 arranged around a core rod 14 as a center core, which will be described later, and abutting 16d is provided. It is attached integrally. In the following description, the entire stripper plate 10 having the pressing block 10a is referred to as the stripper plate 10
Called. The stripper plate 10 functions as a slide holding member. On the slide holding plate 11 side of the core holding plate 12, a hole having a step is formed, and the base end side (left side in FIG. 1) of the core rod 14 is fixed to this hole. Therefore, the core holding plate 1
2 and the movable side mounting plate 13 are the substrate 15 in the prior art.
1 (see FIG. 17). A cylindrical molded product 20 (see FIG. 4) is provided around the core rod 14 that protrudes from the core holding plate 12 and has a pyramidal outer surface formed so that the tip side (the right side in FIG. 1) is alternately inclined. ) Inner circumference 2
The first slide member 15 and the second slide member 16 forming 0b (see FIG. 4) are alternately arranged. In FIGS. 1 and 2, three pieces are arranged. These function as core members.

2 and 3, the outer surfaces 14a and 14b having different inclination angles of the core rod 14 (the outer surface 14a engaging with the first slide member 15 has an outer surface 14 having an inclination angle)
is larger than b, the outer surfaces 14a, 14b and the dovetail groove 14c formed in parallel with the bottom surface are formed in the vertical direction by being inclined by the inclination angle with respect to the central axis of the core rod 14 in the axial direction. , Called for convenience sake)
The dovetail groove 14c is engaged with the dovetail 15c of the first slide member 15 and the dovetail 16c of the second slide member 16 so as to be slidable. Also, the first slide member 1
5 and the second slide member 16 are the first slide member 15
And circumferential projections 15a, 16a formed outward on the base end side (large diameter side) of the second slide member 16 (see FIG. 1).
Is slidable in the radial direction and is held by the slide holding plate 11 while penetrating the slide holding plate 11. The screw transfer portion 15b is a cylindrical molded product 2
It is a portion where an inner peripheral portion 20b (for example, a helicoid screw) is formed as an undercut at 0. Screw transfer part 16b
The same applies (see FIG. 1).

Further, an outer slide member 17 for forming an outer peripheral undercut portion 20c (see FIG. 4) of the cylindrical molded product 20 is brought into contact with the surface of the stripper plate 10 facing the fixed-side mold plate 4, and , This outer slide member 1
7 is slidably provided in the radial direction (that is, in the radial direction with respect to the axis of the core rod 14). This outer slide member 1
A hook-shaped step 7 functions as a work holding means attached to a slide holding member (corresponding to the stripper plate 10), forms an outer peripheral undercut portion 20c of the cylindrical molded product 20 inside, and holds this when the mold is opened. It has a part 17b. Since the outer slide member 17 forms the outer peripheral undercut portion 20c of the cylindrical molded product 20, the outer slide member 17 is divided into six equal parts in the circumferential direction. In addition, in FIG. 1, a part of the upper side of the outer slide member 17 is shown by a broken line, and the illustration thereof is omitted. PL is an abbreviation for a parting line and indicates a contact surface between the fixed-side template 4 and the stripper plate 10. Therefore, it can be said that the plates of the movable mold 2 and the fixed mold 1 are in contact with each other. Hereinafter abbreviated as PL.

Further, as shown in FIG. 5, the angular cam 21 has a taper portion 21b and a straight portion 21a,
The cross section has a substantially rectangular shape (see the view on arrow A in FIG. 5). During the initial mold clamping operation, the tapered portion 21b (specifically, the tapered hole 17a of the tapered portion 21b) is formed in the tapered hole 17a of the outer slide member 17 (specifically, the surface portion facing the tapered surface of the tapered hole 17a). The outer slide member 17 is formed by the taper fitting on the surface opposite to the taper surface).
Is moved inward in the circumference, and the outer slide member 17 is stopped by the straight portion 21a in the latter half of the mold clamping operation. As shown in FIG. 1, in the angular cam 21, the base end side of the straight portion 21 a is planted in the fixed side template 4. The angular cams 21 are arranged at six positions around the core rod 14 like the outer slide member 17. Six holes are formed in the stripper plate 10 so that the taper portion 21b of the angular cam 21 can be housed during mold clamping.

In FIG. 1, the magnets 18 and 18 are attached to the outer peripheral surfaces of the stripper plate 10 and the fixed-side mold plate 4, respectively, so that they can be attracted to and maintained by each other, and the stripper plate 10 and the fixed-side member are fixed with a desired force. It can be fastened to the template 4 and functions as fastening means. The pulling link 35 is a member that connects and fixes the slide holding plate 11 and the fixed-side template 4 such that they can be opened by a predetermined amount, and bolts () attached to each side surface of the slide-holding plate 11 and the fixed-side template 4 ( Only the head of the bolt is visible).

Next, an injection molding method of a cylindrical molded product using the injection molding die having the above construction will be described with reference to FIGS. 6 to 11 sequentially illustrate the molding steps of the injection mold attached to the injection molding machine, and the injection molding machine is not shown. 7 to 11, the runner 5a formed on the fixed core member 5 is not shown. FIG. 6 shows the mold closed state with the resin flow path 7a and the runner 5
a, the fixed-side template 4 through the pinpoint gate 5b,
A state in which a cylindrical molded product 20 is molded by a resin material as a molten material injection-molded in a space (cavity) formed by each of the first slide member 15, the second slide member 16, and the fixed core member 5 It is in. After proper resin cooling is completed, as shown in FIG. 7, the pin gate 5b is gate-cut by the mold opening operation of the injection molding machine, and the fixed side mold plate 4 and the runner drop plate 6 are separated. At the same time, the fixed core member 5 moves toward the fixed mounting plate 3 side by the urging force of the spring 32. Therefore, from the inner peripheral portion 20b of the molded product 20 shown in FIG. Will evacuate. At this time, the moving amount of the fixed core member 5 is regulated by the stop pin 9 screwed to the fixed mold plate 4.

Next, as shown in FIG. 8, the mold opening operation of the injection molding machine is continued, and the core holding plate 12 and the movable side mounting plate 13 are integrated with the slide holding plate 11 with PL kept closed. To separate in the mold opening direction. At this time, the core rod 14 attached to the core holding plate 12 has the first slide member 15 and the second slide member 16
At the same time as being separated (moved) relative to the circular protrusion 15a of the first slide member 15, the second slide member 1
Since the circumferential projections 16a of 6 are guided by the slide holding plate 11, the first slide member 15 and the second slide member 16 move in the radial center direction (direction toward the axis of the core rod 14). Therefore, the screw transfer portions 15b and 16b (see FIG. 1) that form the helicoid screws that undercut the first slide member 15 and the second slide member 16 are separated from the inner peripheral portion 20b of the cylindrical molded product 20.
The mold opening operation of FIGS. 6 to 8 corresponds to the mold opening initial operation.

Further, the mold opening operation of the injection molding machine proceeds, and as shown in FIG.
L opens. At this time, since the outer slide member 17 does not move until the taper portion 21b of the angular cam 21 planted in the fixed-side mold plate 14 comes into contact with the taper hole 17a of the outer slide member 17, the outer periphery of the cylindrical molded product 20. The cylindrical molded product 20 is moved to the movable mold 2 by the undercut portion 20c.
And is separated from the hole forming surface 4a of the fixed-side template 4.

Further, as the mold opening operation of the injection molding machine progresses, as shown in FIG. 10, the movement of the movable side mold 2 and the fixed side mold 1 is restricted by the pulling link 35, and at this time, the angular cam. Since the taper portion 21 b of 21 presses the taper hole 17 a of the outer slide member 17, the outer slide member 17 is attached to the outer peripheral undercut portion 20 of the cylindrical molded product 20.
The fixed holding state of c is released, and the runner drop plate 6 is stopped from the fixed side mounting plate 3 by the stop pin 30a.
Then, the runner lock pin 8 is pulled out from the runner 5a. In this state, the mold opening operation is completed. The mold opening operation up to FIGS. 9 and 10 corresponds to the latter half operation of the mold opening.

FIG. 11 further shows a projecting state for taking out the cylindrical molded product 20, and in this example, the projecting rod 34 is extruded by a projecting mechanism (not shown) of the injection molding machine, so that the fixed side mold plate 4 is pushed. The stripper plate 10 is moved toward. The movement of the stripper plate 10 widens the gap between the slide holding plate 11 and the stripper plate 10, and the first slide member 1 held by the slide holding plate 11
5. The cylindrical molded product 20 moves in the moving direction of the stripper plate 10 with respect to the second slide member 16. By the movement of the cylindrical molded product 20, the cylindrical molded product 20
Since the lengths of the first slide member 15 and the second slide member 16 which are in the inner side of the first slide member 15 on the tip end side are reduced, the cylindrical molded product can be easily taken out from the stripper plate 10. Of course, even in the state up to FIG. 10, if the cylindrical molded product 20 can be taken out, this operation is unnecessary. By the above operation, the cylindrical molded product can be molded without causing deformation or scratches.

According to the present embodiment, without changing the conventional molding cycle, the cylindrical molding having the molded undercut portions on the inner and outer peripheral portions is performed by the sequential movement of the respective mold constituents when the mold is opened. The product can be taken out from the injection mold without being scratched or deformed, and the quality in mass production can be stabilized.

(Embodiment 2) FIGS. 12 to 15 show Embodiment 2, FIG. 12 is a vertical cross-sectional view of an injection mold of a cylindrical molded product, and FIG. 13 is a vertical cross-section of the injection mold in a mold closed state. FIG. 14 is a vertical cross-sectional view of the injection mold in the first stage mold opening state,
FIG. 15 is a vertical cross-sectional view of the injection molding die in the mold opening state in the second stage. The present embodiment is different from the first embodiment in that the molded cylindrical molded product remains in the fixed side mold, and other parts are the same as those in the first embodiment, and therefore only different parts will be described and the same members will be described. Are denoted by the same reference numerals and description thereof will be omitted.

In the injection molding die of this embodiment shown in FIG. 12, the outer peripheral undercut portion 20c formed on the outer peripheral portion of the cylindrical molded product 20 shown in FIG. The outer slide member 17 is used for molding. Therefore, as compared with the first embodiment, the outer slide member 17 for forming the outer peripheral undercut portion 20c formed on the outer peripheral portion of the cylindrical molded product 20 is arranged on the fixed mold 1 side. Also, the molded product 20
The outer peripheral portion 20a is molded by the stripper plate 10 of the movable mold 2, and the fixed core member 5 in FIG. 1 is not used.

In FIG. 12, as in the first embodiment,
The fixed-side mold 1 has a fixed-side mold plate 4, a runner drop plate 6, and a fixed-side mounting plate 3, and a support pin 36a planted in the fixed-side mounting plate 3 has a runner-fall plate 6 and a fixed-side mold. The plate 4 is slidably fitted. Further, the runner drop plate 6 has stop pins 30a, 3
0b are screwed from different directions, and the fixed-side mold plate 4,
The runner drop plate 6 and the fixed side attachment 3 are separable from each other by a predetermined amount in the mold opening direction of an injection molding machine (not shown). The fixed-side template 4 that functions as a slide holding member is an outer peripheral undercut portion 20c of the cylindrical molded product 20.
An outer slide member 17 (which functions as a work holding means) that forms a groove is slidably provided in the radial direction. PL
Is an abbreviation for parting line, and indicates a contact surface between the stationary mold plate 4 and the stripper plate 10. Therefore, it can be said that the plates of the movable mold 2 and the fixed mold 1 are in contact with each other. Hereinafter, it is abbreviated as PL.

An angular cam 21 is arranged on the stripper plate 10 of the movable mold 2, and the angular cam 21 has a straight portion 21a and a taper portion 21b as shown in FIG. Are planted in the stripper plate 10. The tapered portion 21b of the angular cam 21 has a tapered hole 17a of the outer slide member 17.
The holes of the fixed side mold plate 4 and the holes of the runner drop plate 6 formed at positions corresponding to
During the initial mold clamping operation, the tapered portion 21b (specifically, the tapered hole 1) is formed in the tapered hole 17a of the outer slide member 17 (specifically, the surface portion facing the tapered surface of the tapered hole 17a).
The outer slide member 17 is moved inward in the circumferential direction by the taper fitting of the surface portion of the taper portion 21b on the side opposite to the taper surface of 7a), and the straight portion 21a (see FIG. 5) is used in the latter half of the mold clamping operation. Thus, the slide member 17 stops. The stripper plate 10 has a circular hole-shaped surface 10b for forming the outer peripheral portion 20a of the cylindrical molded product 20, that is, for forming the outer peripheral surface of the cylindrical molded product 20 without the outer peripheral undercut portion 20c. Has
Functions as a cavity member. Magnets 18, 18 as fastening means are attached to the side surface of the fixed-side mold plate 4 (slide holding member) of the fixed-side mold 1 and the side surface of the stripper plate 10 of the movable-side mold 2, respectively. .
Other configurations of the injection molding die are similar to those of the first embodiment.

Next, an injection molding method of a cylindrical molded product using the injection molding die having the above construction will be described with reference to FIGS. 13 to 15. 13 to 15 sequentially show the molding steps of the injection mold attached to the injection molding machine, and the illustration of the injection molding machine is omitted. FIG. 13 shows the mold closed state, which is the state in which the cylindrical molded product 20 is molded as in the first embodiment. After proper resin cooling is completed, as shown in FIG. 14, the pinpoint gate 5b is gate-cut by the mold opening operation of the injection molding machine, and the fixed side mold plate 4 and the runner drop plate 6 are separated. Further, the mold opening operation of the injection molding machine is continued, and the core holding plate 12 and the movable side mounting plate 13 are integrally separated from the slide holding plate 11 in the mold opening direction while PL is closed. After that, the core rod 14 as the center core retracts in the mold opening direction,
By the circumferential protrusions 15a, 16a of the first slide member 15 and the second slide member 16, the first slide member 15,
The second slide member 16 moves toward the axial center of the core rod 14, and from the inner peripheral portion 20b of the cylindrical molded product 20, the first slide member 15, the screw transfer portion 15b of the second slide member 16,
16b (see FIG. 12) separates. 13 and 14
The mold opening operation of corresponds to the mold opening initial operation.

Further, as the mold opening operation of the injection molding machine progresses, the parting surface (PL surface) between the movable side mold 2 and the fixed side mold 1 is opened, and first the stripper plate 10 is formed before the state shown in FIG. The fixed side template 4 is separated from the fixed side mold plate 4, and the straight portion 21a of the angular cam 21 is initially formed at the time of this separation.
(See FIG. 5) along the taper hole 1 of the outer slide member 17.
Since the straight portion of 7a moves relatively, and therefore the outer slide member 17 does not move, the outer peripheral undercut portion 20c of the cylindrical molded product 20 has the hook-shaped step formed inside the outer slide member 17. By being held by the portion 17b (see FIG. 5), the cylindrical molded product 20 is held by the stationary mold plate 4, and in this state, the outer peripheral portion 20a of the cylindrical molded product 20 has a circular hole shape of the stripper plate 10. The close contact state is released from the hole forming surface 10b (see FIG. 12) to move. As the mold opening progresses from this state, as shown in FIG. 15, the taper hole 17a of the outer slide member 17 is formed by the taper portion 21b of the angular cam 21.
Is pushed, the outer slide member 17 moves outward in the radial direction and separates from the cylindrical molded product 20.

Further, as the mold opening operation of the molding machine progresses, the runner lock pin 8 comes off from the runner 5a formed on the stationary mold plate 4, as shown in FIG. The mold opening operation is completed in this state. The mold opening operation up to FIG. 15 corresponds to the latter half opening operation.

According to the present embodiment, in addition to the same effects as in the first embodiment, since the cylindrical molded product is held in the fixed side mold instead of remaining in the movable side mold, the movable side mold is obtained. It is not necessary to use the ejecting mechanism of the cylindrical molded article (ejecting rod 34 in FIG. 1 of Embodiment 1 and the ejecting means provided in the injection molding machine) provided in the above, and the mold structure can be simplified. .

[0043]

According to the invention of claim 1, 2, 3 or 4, the cylindrical molded product can be molded and shrunk in the axial direction, and the pressing force of the outer peripheral portion of the molded product toward the cavity member is reduced. The one end side of the outer peripheral portion of the cylindrical molded product is reduced by the work holding means attached to the slide holding member,
The cylindrical molded product can be easily removed from the cavity member by pulling out most of the outer peripheral portion of the molded product from the hole molding surface of the cavity member, so that the conventional molded cycle can be removed without changing the conventional molding cycle. It is possible to reduce quality and deformation and stabilize the quality in mass production.

According to the invention of claim 2, in addition to the above effects, the cylindrical molded product can be uniformly molded and shrunk in the axial direction thereof, and the internal strain of the cylindrical molded product is reduced. It is possible to ensure the shape accuracy of a cylindrical molded product in which an undercut shape such as a helicoid groove or a cam groove is provided on the inner peripheral surface of the product, and to easily separate from the undercut shape.

According to the invention of claim 3, in addition to the above effects, the core member forming the inner peripheral portion of the molded product is the center core before the hole molding surface of the cavity member and the outer peripheral portion of the cylindrical molded product are separated from each other. Since the core member is moved in the mold opening direction relative to the inner peripheral portion of the cylindrical molded product after moving toward the axial center of the cylindrical molded product, the contraction of the cylindrical molded product is not hindered and the cylindrical molded product is prevented. Can be easily taken out of the injection mold.

According to the fourth aspect of the present invention, in addition to the above effects, an undercut portion is formed on the outer peripheral portion of the cylindrical molded product, and the undercut portion is utilized to ensure that the cylindrical molded product is a cavity member. Since the cylindrical molded product and the cavity member are separated from each other, it is possible to reliably prevent the deformation and the scratch due to the peeling of the cylindrical molded product and the cavity member.

According to the fifth aspect of the present invention, the cylindrical molded product and each member of the injection molding die are smoothly released from each other, and the cylindrical molded product is held in the fixed side mold or the movable side mold and taken out. Since it is in the easy state, it is possible to reliably prevent the formed cylindrical molded product from being deformed or damaged and to stabilize the quality in mass production.

According to the sixth aspect of the invention, the cylindrical molded product and the respective members of the injection mold are smoothly released from each other, and the cylindrical molded product is held in the work holding means so that it can be easily taken out. Definitely prevent deformation and scratches on the formed cylindrical molded product,
The quality in mass production can be stabilized, and the cylindrical molded product can be easily handled.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an injection molding die of a cylindrical molded product according to a first embodiment.

FIG. 2 is a perspective view of a first slide member according to the first embodiment.

FIG. 3 is a perspective view of the core rod according to the first embodiment.

FIG. 4 is a vertical cross-sectional view of the cylindrical molded product according to the first embodiment.

FIG. 5 is a vertical sectional view showing the engagement between the angular cam and the outer slide member according to the first embodiment.

FIG. 6 is a vertical cross-sectional view of the injection-molding die in the mold-closed state according to the first embodiment.

FIG. 7 is a vertical cross-sectional view of the injection mold in the first stage in the mold open state according to the first embodiment.

FIG. 8 is a vertical cross-sectional view of the injection molding die in the mold opening state in the second stage of the first embodiment.

FIG. 9 is a vertical cross-sectional view of the injection mold in the mold open state of the third stage of the first embodiment.

FIG. 10 is a vertical cross-sectional view of the injection mold in the mold open state at the final stage of the first embodiment.

FIG. 11 is a vertical cross-sectional view of the injection mold of the cylindrical molded product according to the first embodiment in a protruding state.

FIG. 12 is a vertical cross-sectional view of an injection molding die of a cylindrical molded product according to a second embodiment.

FIG. 13 is a vertical cross-sectional view of an injection molding die according to a second embodiment in a mold closed state.

FIG. 14 is a vertical cross-sectional view of the injection mold of the second embodiment in the mold open state in the first stage.

FIG. 15 is a vertical cross-sectional view of the injection mold in the second stage mold open state according to the second embodiment.

FIG. 16 is a plan view of the core in an injection-molded state attached to a molding die according to the related art, as viewed from the y direction in FIG.

FIG. 17 is a cross-sectional view through the axis along the line ww of FIG. 16 of the prior art.

FIG. 18 is a diagram showing the positions of the components of the molding die having the opening core of the prior art attached thereto in the first stage of mold opening.

FIG. 19 is a view showing the positions of the components of the molding die having the opening core of the prior art attached thereto in the second stage of mold opening.

FIG. 20 is a diagram showing the positions of the components of the molding die having the opening core of the prior art attached thereto in the third stage of mold opening.

[Explanation of symbols]

1 Fixed mold 2 Movable mold 4 Fixed side template 10 stripper plate 14 core rod 15 First slide member 16 Second slide member 17 Outer slide member

Claims (6)

[Claims] 1. An injection molding die for molding a cylindrical molded product by a space formed when the parting surfaces of the movable mold and the stationary mold facing each other are in contact with each other. A core member that is attached to the movable side mold so as to form a peripheral part and has an outer peripheral surface that is cylindrical when combined with each other, and the movable side mold so as to form the outer peripheral part of the cylindrical molded product. Mold or a fixed-side mold, and a cavity member formed with a circular hole-shaped molding surface facing the outer peripheral surface of the core member, and the movable-side mold and the fixed-side mold are closed. The movable side mold and the fixed side mold during the initial operation of the mold opening after injection and filling of the molten material into the space between the outer peripheral surface of the core member and the hole forming surface of the cavity member formed in the closed state. Tighten A fastening means for releasing the fastening between the movable side die and the fixed side die during the latter half operation of the die opening, and the core member at the retracted position from the inner peripheral portion of the cylindrical molded article during the die opening initial operation. A center core to be moved, and a work holding means attached to a slide holding member arranged to face the cavity member so as to hold the outer peripheral portion of the cylindrical molded product during the latter half operation of the mold opening are provided. An injection molding die for cylindrical molded products. 2. The center core is composed of core rods having pyramidal outer surfaces having different inclination angles and extending in the mold opening direction, and the core members are respectively arranged on the outer surfaces of the core rods and the cylinders. The molded product comprises a plurality of slide members whose outer peripheral surfaces are cylindrical when assembled so as to form the inner peripheral portion of the molded product, and the plurality of slide members move in the mold opening direction of the core rod. 2. The injection molding die for a cylindrical molded product according to claim 1, wherein each of them is configured to move toward the axis of the core rod. 3. The core member molds an inner peripheral portion of the cylindrical molded product, and the center core of the center core is subjected to an initial operation of mold opening before a hole molding surface of the cavity member and an outer peripheral portion of the cylindrical molded product are separated from each other. The structure is such that it moves toward the axial center and separates from the inner peripheral portion of the cylindrical molded product, and then retreats in the mold opening direction relative to the inner peripheral portion of the cylindrical molded product. 1. An injection molding die for a cylindrical molded article according to 1. 4. The work holding means comprises a plurality of outer slide members forming an outer undercut portion that is convex or concave on the outer peripheral portion of the cylindrical molded product, and the movable side mold starts opening the mold. The injection molding die for a cylindrical molded product according to claim 1, wherein the cylindrical molded product is held by the slide holding member via the external undercut portion until the above. 5. An injection molding method for molding a cylindrical molded product by a space formed when the parting surfaces of the movable mold and the stationary mold facing each other are in contact with each other. A core member attached to the movable side mold so as to form a peripheral part and having a cylindrical outer peripheral surface, and the movable side mold or the fixed side mold so as to form the outer peripheral part of the cylindrical molded product. A cavity member used as a component of a mold and having a cylindrical hole forming surface facing the outer peripheral surface of the core member, and facing the cavity member so as to mold one end side of the cylindrical molded product. The movable holding mold and the fixed holding mold in a closed state, and the parting surfaces are brought into contact with each other, and the outer peripheral surface of the core member and the cavity. The hole forming surface of the material and the slide holding member form the space portion, the space material is injection-filled with the molten material, and thereafter, the outer peripheral surface of the core member is kept in contact with the parting surface. Is moved toward the axis of the cylindrical molded product to retract the outer peripheral surface of the core member from the inner peripheral portion of the cylindrical molded product, and then the fastening between the movable side mold and the fixed side mold is released. Then, the parting surface is separated to separate the outer peripheral portion of the cylindrical molded product from the hole molding surface of the cavity member, and the cylindrical molded product is used as a fixed-side mold or a movable-side mold having no cavity member. An injection molding method for a cylindrical molded product, characterized in that the mold opening operation is completed while the mold is held, and the cylindrical molded product is taken out. 6. The cylindrical molded product is replaced by completing the mold opening operation while holding the cylindrical molded product in a fixed mold or a movable mold that does not have the cavity member, and taking out the cylindrical molded product. 6. The method of injection molding a cylindrical molded product according to claim 5, wherein the mold opening operation is completed while the product is held by the work holding means mounted on the slide holding member, and the cylindrical molded product is taken out.