JP2511774Y2 - Extrusion molding device with attachment / detachment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an improvement of an extrusion molding apparatus provided with an attachment / detachment device attached above a blow molding apparatus.

(Prior Art) As the extrusion molding apparatus described above, as already disclosed by the applicant in Japanese Patent Application No. 63-105936, a core molding that is detachably provided on the apparatus body and expands in a taper shape to the lower end of the outer peripheral surface toward the lower end. A core having a surface, and a die having a die molding surface that surrounds the core and that faces the lower end of the inner peripheral surface and that has a die molding surface that tapers toward the lower end,
It is known to extrude a parison from between the core molding surface and the die molding surface and supply the parison to a blow molding device.

In this case, the diameters and inclination angles of the lower ends of the core molding surface and the die molding surface must be set corresponding to the parison size and molding conditions, respectively. Therefore, the conventional extrusion molding device, every time the size of the parison to be extruded is different,
The core and the die were set as one set and replaced with a predetermined one.

(Problems to be solved by the invention) However, when performing this replacement work, in particular, the die is formed thick to withstand the pressure received from the parison and formed to have a predetermined size so as to surround the core. Therefore, since it has a large weight (usually about 100 kg), it is difficult to replace the die.

Moreover, in order to cope with various needs of resin molded products in recent years, in the extrusion molding device of the parison, the work of replacing the core and the die is frequently performed, so that the above problem is serious.

In view of the above, the present invention aims at facilitating core and die replacement work.

(Means for Solving the Problem) In order to achieve the above object, the invention of claim (1) is
The die is detachably divided into a die upper part and a die lower part having a die molding surface, and when changing the size of the parison, only the core and the die lower part can be replaced and a common attaching / detaching device can be used. To do.

Specifically, the solution means devised by the invention of claim (1) is that a cylindrical core upper part detachably provided in the apparatus main body and a lower end of the core upper part are continuously and integrally provided and extend from the outer peripheral surface to the lower end. A core having a core lower portion having a core molding surface that expands in a taper shape; and a die having a die molding surface that surrounds the core and that faces the core molding surface on the inner peripheral surface and that expands in a taper shape toward the lower end. It is premised on an extrusion molding apparatus which comprises a core molding surface and a die molding surface. The die is composed of a die upper portion and a die lower portion which are detachably divided into upper and lower portions, and the die molding surface is provided on the inner peripheral surface of the die lower portion, and the core and the die lower portion are attached and detached. The attachment / detachment device is provided. The attachment / detachment device has a table that can be rotated and moved up and down, a receiving portion provided on the table for receiving the detached core and the lower portion of the die, and a concave portion having a circular cross section at the center of the upper surface. Further, a receiving member having a working window formed therethrough for removing a mounting bolt for attaching the lower die to the upper die in the receiving portion, and a receiving member supported in a concave portion of the receiving member so as to be able to move up and down but not to rotate relative to each other. The core attachment / detachment member attaches and detaches the core to / from the apparatus main body when descending, and the drive means supported by the receiving member to move the core attachment / detachment member up and down. When the table is raised so that the receiving member receives the core and the lower part of the die while being rotated so as to face the bolt, the operation of the drive means is performed. Lowers the core detachable member and those configured to be able perform detachment operations of the die bottom by removing the mounting bolts through the working window with disengaging the core from the apparatus main body.

Further, in the invention of claim (2), the heights of the core and the lower part of the die are made constant and the distances between the lower end face of the core and the lower end face of the die and the upper end face of the blow molding device are made constant even for parisons of different sizes. In order to maintain this, the outer peripheral surface of the lower part of the core and the inner peripheral surface of the lower part of the die are made to have different inclination angles between the upper side and the lower side, and only the lower side of each is set to a predetermined inclination angle.

Specifically, the solution means devised by the invention of claim (2) is the structure of claim (1), in which the outer peripheral surface of the core lower part has the core molding surface formed at a predetermined inclination angle toward the lower end, An inner peripheral surface of the die lower part is composed of a core intermediate surface connecting the upper end of the core molding surface and the lower end of the outer peripheral surface of the core upper part.
A structure comprising the die molding surface formed at a predetermined inclination angle corresponding to the core molding surface toward the lower end, and a die intermediate surface connecting the upper end of the die molding surface and the inner peripheral surface lower end of the die upper part. It is something to add.

(Operation) According to the configuration of the invention of claim (1), the die is detachably divided into an upper die portion and a lower die portion, and the die molding surface is provided on the inner peripheral surface of the lower die portion. Extrusion of parison of different sizes is possible by simply replacing and. Moreover, since this replacement work can be performed by rotating and lifting the table and driving the driving means, the replacement work of the core and the lower part of the die is easy. In particular, the replacement of the core and the lower part of the die can be performed by a single attaching / detaching device, that is, a single rotating / lifting mechanism, instead of being performed by a separate attaching / detaching device. And can be simplified.

According to the configuration of the invention as set forth in claim (2), the outer peripheral surface of the lower part of the core connects the core molding surface formed to the lower end with a predetermined inclination angle, and the upper end of the core molding surface and the lower end of the outer peripheral surface of the core upper part. The inner peripheral surface of the lower part of the die is composed of a core intermediate surface, and the inner peripheral surface of the die has a die forming surface formed at a predetermined inclination angle toward the lower end, and the die middle connecting the upper end of the die forming surface and the lower end of the inner peripheral surface of the upper die. Since it consists of a surface and a parison of different sizes, by changing the inclination angle of the core intermediate surface and the die intermediate surface while maintaining the core molding surface and the die molding surface at a predetermined inclination angle, Since the height of the lower part of the die can be maintained at a constant value, the distance between the lower end surface of the core and the lower end surface of the die and the upper end surface of the blow molding device can be kept constant.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows a sectional structure of an extrusion molding apparatus A according to an embodiment of the present invention. The extrusion molding apparatus A extrudes a parison having a three-layer structure.

In FIG. 3, reference numeral 10 denotes a head member, and an inner cylinder 11 and an outer cylinder are provided at a lower portion of the head member 10.
A cylinder member 13 composed of 12 is provided. Between the inner cylinder 11 and the outer cylinder 12, a ring piston 14 slidable on the outer peripheral surface of the inner cylinder 11 and the inner peripheral surface of the outer cylinder 12 is arranged.
14 is vertically movable in conjunction with the plunger 16.

Inside the inner cylinder 11, a cylindrical core 2 supported by a core support rod 18 penetrating the inside thereof and having a large diameter portion 20a at the bottom is formed.
0 is provided, and a core 22 detachably attached to the lower end of the core support rod 18 is provided below the core 20.

An annular member 24 is provided between the outer cylinder 12 and the large diameter portion 20a of the core 20, and the annular member 24 has an inner resin passage and an inner resin passage extending vertically in the inner peripheral surface and the outer peripheral surface thereof, respectively. An outer resin passage is provided, and an annular resin passage that extends horizontally in an annular shape and is opened downward is provided between the inner and outer resin passages. Further, an annular die 26 surrounding the core 22 is provided on the lower surface of the outer cylinder 12.

The inner peripheral surface of the inner cylinder 11 and the outer peripheral surface of the core 20 constitute an annular flow passage 28 through which the molten main material resin forming the first layer and the third layer of the parison flows. By the tapered lower surface of the inner cylinder 11, the tapered lower surface of the ring piston 14, the tapered upper surface of the large diameter portion 20a of the core 20, and the upper surface of the annular member 24, the flow passage is formed.
Main material storage chamber that stores the main resin that has flowed down 28
30 are made up. Furthermore, the outer peripheral surface of the core 20 and the core 22
The outer peripheral surface of the outer cylinder 12, the inner peripheral surface of the outer cylinder 12 and the inner peripheral surface of the die 26 cause the resin to become a parison and to be extruded as an outflow passage.
31 are configured.

A main material feeder 32 for supplying the main material resin to the flow passage 28 is provided on the side portion of the head member 10, and the annular member 24 is provided.
On one side (the right side in FIG. 3), an auxiliary material feeder 34 for supplying the auxiliary material resin forming the second layer of the parison to the annular resin passage of the annular member 24 is provided. Machine 32
The main material supplied from the above separates into the first layer and the third layer when flowing through both the inner and outer resin passages of the annular member 24, and between the first layer and the third layer, the auxiliary material feeder The auxiliary material supplied from 34 is interposed as the second layer.

Further, on the other side of the annular member 24 (on the left side in FIG. 3), an adhesive supply machine for supplying an adhesive into the inside of the annular member 24 via the first adhesive passage 36 and the second adhesive passage 38. 40 is provided, and the adhesive supplied through the first adhesive passage 36 is supplied inside the annular member 24 between the first layer and the second layer through the second adhesive passage 38. The adhesive is an annular member 24
Is supplied between the second layer and the third layer inside.

In the extrusion molding apparatus having the above structure, the present embodiment is characterized by the core 22 and the die 26, and the core 22 and the die 26 will be described below with reference to FIGS. 1 and 2.

Fig. 1 shows the cross-sectional structure of the core 22A and die 26A used for extruding a small-diameter parison, and Fig. 2 shows the cross-sectional structure of the core 22B and die 26B used for extruding a large-diameter parison. ing.

Each of the core 22A and the core 22B is composed of a cylindrical core upper part 22a and a truncated cone-shaped core lower part 22b, and the core upper part 22a is fitted in a circular cross-section connecting recess 20b provided in the lower part of the core 20. It has a possible diameter.

On the upper surface of the core upper portion 22a, a mounting recess 22 having a circular cross section for mounting the core 22A (22B) on the common core support rod 18 is provided.
c is provided, an annular groove 22d is formed on the inner peripheral surface of the mounting recess 22c, and the annular groove 22d has four vertical grooves 22e provided at equal intervals and extending in the vertical direction. By core 2
It opens at the top of 2A (22B).

On the other hand, the outer peripheral surface of the lower end portion of the core support rod 18 is provided with four protrusions 18a protruding at equal intervals.
The 2A (22B) is moved up and down with the vertical groove 22e and the protrusion 18a of the core support rod 18 facing each other, and then rotated by, for example, 45 degrees in the circumferential direction to be attached to and detached from the core support rod 18. It is possible to install.

The lower surface of the core lower portion 22b has a large diameter upper portion 22f and a small diameter lower portion.
A detachable concave portion 22h having a circular cross-section including 22g is provided, and an attachable / detachable hole 22i having a circular cross-section is provided on the upper surface of the upper portion 22f of the detachable concave portion 22h, and at the inner peripheral surface of the lower portion 22g. Are four notch recesses 22j at positions corresponding to the vertical grooves 22e.
Is provided.

The outer peripheral surface of the core lower portion 22b is divided by a bent portion 22k into an outer peripheral surface upper portion 22l and an outer peripheral surface lower portion 22m.

The outer peripheral surface lower portion 22m of the core 22A and the core 22B has a dimension such that the outer diameter of the lower end portion is suitable for the diameter of the parison (for example, the core 22A: 26
2mm, core 22B: 342mm), while the inclination angle is set to a predetermined angle suitable for feeding the parison to the mold of the blow molding machine (for example, with respect to the vertical line). 28 degrees), and the lower portion 22m of the outer peripheral surface constitutes the core molding surface.

Further, the outer peripheral surface upper portions 22l of the cores 22A and 22B are formed on a core intermediate surface that connects the outer peripheral surface lower end of each core upper portion 22a and the outer peripheral surface lower portion 22m upper end of each core lower portion 22b without steps. .

The die 26A and the die 26B are divided into die upper portions 42A and 42B and die lower portions 44A and 44B, respectively.

An annular convex portion 42c is provided on the lower surface of the die upper portion 42A (42B), and the annular convex portion 42c is provided on the inside of the upper surface of the die lower portion 44A (44B).
An annular recess 44c that engages with c is provided. By engaging the annular convex portion 42c and the annular concave portion 44c and screwing the die lower part mounting bolt 46 into the die upper part 42A (42B) through the through hole provided in the die lower part 44A (44B). , The lower die 44A (44B) is detachably attached to the upper die 42A (42B). In this case, the inner peripheral surface of the annular convex portion 42c and the outer peripheral surface of the annular concave portion 44c are formed into tapered surfaces that spread downward, and the die lower portion 44A (44B) of the die lower portion 44A (44B) due to the pressure of the parison flowing in the outflow passage 31 is formed. Prevents deviation. Further, on the inner peripheral surface of the through hole provided in the die lower portion 44A (44B), a bolt having a diameter slightly larger than that of the die lower portion mounting bolt 46 is provided.
A screw thread is provided to which 60 (see FIG. 5) is screwed.

An engaging protrusion 42d is provided on the upper surface of the die upper portion 42A (42B), and the engaging protrusion 42d is fitted into the engaging recess 12a provided on the lower surface of the outer cylinder 12 and the die mounting bolt is provided. The die upper portion 42A (42B) is screwed into the lower surface of the outer cylinder 12 by penetrating the die upper portion 42A (42B).
B) As a result, the die 26A (26B) is detachably attached to the outer cylinder 12.

The inner peripheral surface of the die lower portion 44A (44B) is divided by a bent portion 44d into an inner peripheral surface upper portion 44e and an inner peripheral surface lower portion 44f.

The inner peripheral surface lower portions 44f of the die lower portions 44A and 44B are formed in a shape corresponding to the outer peripheral surface lower portions 22m of the cores 22A and 22B, respectively, and form die molding surfaces. That is, the die bottom 44
The outer diameter of the lower end of A and 44B is suitable for the diameter of the parison to be extruded (for example, die lower part 44A: 280mm, die lower part 44B: 360).
mm), but the inclination angle is set to a predetermined angle (for example, 16 degrees with respect to the vertical line) suitable for feeding the parison to the mold of the blow molding machine. Has been done.

Further, each inner peripheral surface upper portion 44e of the die lower portions 44A and 44B is formed on a die intermediate surface that connects the upper end of the inner peripheral surface lower portion 44f and the inner peripheral surface lower end of the die upper portion 42A (42B) without steps. .

As described above, since the die 26 is divided into the die upper portion 42A (42B) attached to the outer cylinder 12 and the die lower portion 44A (44B) having the die molding surface, the core 22 and the die lower portion are formed.
By simply replacing 44A (44B), extrusion of parisons with different diameters can be performed.

Further, conventionally, the outer peripheral surface of the core lower portion 22b has the above-mentioned Japanese Patent Application No.
As shown in FIG. 1 of 3-105936, it is formed on a flat inclined surface having a predetermined angle suitable for supplying the parison to the mold of the blow molding machine, and correspondingly, The inner peripheral surface of the lower die 44A (44B) also includes the upper die 42A (42
It was formed into a flat inclined surface having a predetermined angle suitable for feeding the parison to the mold of the blow molding machine, continuing from the lower end of B). Therefore, as the diameter of the parison increases, the lower ends of the core lower part 22b and the die lower part 44A (44B) are positioned lower, and when the parison diameter decreases, the lower ends of the core lower part 22b and the die lower part 44A (44B) move upward. Will be located. For this reason, the upper surface of the blow molding machine must be set at a position where the parison having the largest diameter can be extruded, that is, at a lower position, and the lower end surface of the core lower portion 22b and the die lower portion 44A (44B) and the blow molding machine When the core 22 and the die 26 are replaced with each other, the distance from the upper surface becomes large, and the parison remaining between the core lower portion 22b and the die lower portion 44A (44B) becomes long, resulting in unavoidable loss of resin material.

However, as described above, the outer peripheral surface of the core lower portion 22b is divided into the outer peripheral surface upper portion 22l and the outer peripheral surface lower portion 22m, and the outer peripheral surface of the die lower portion 44A (44B) is divided into the inner peripheral surface upper portion 44e and the inner peripheral surface lower portion 4m.
The outer peripheral surface lower part 22m (core molding surface) and the inner peripheral surface lower part 44f (die molding surface) are each divided into 4f at a predetermined inclination angle suitable for supplying the parison to the mold of the blow molding machine. The outer peripheral surface upper part 22l and the inner peripheral surface upper part 44e are formed on the core intermediate surface and the die intermediate surface that connect the outer peripheral surface lower part 22m and the inner peripheral surface lower part 44f to the upper peripheral surface and inner peripheral surface, respectively. did. Therefore, when the diameter of the parison changes, the core lower portion 22b and the die lower portion 44A (44B) are changed by changing the inclination angles of both the intermediate surfaces while keeping the inclination angles of the core molding surface and the die molding surface constant. ) Can be kept constant, the distance between the lower end of the core lower part 22b and the lower part of the die 44A (44B) and the upper surface of the blow molding machine can be set to the minimum, so the material loss of the resin can be minimized. You can bear.

4 is a cross-sectional structure of a mounting / demounting device B for mounting / demounting the core 22 and the die lower part 44A (44B) with respect to the core support rod 18 and the die upper part 42A (42B), and FIG. 5 is an exploded structure of the mounting / demounting device B. Are shown respectively.

In FIG. 4, reference numeral 50 denotes a table that can be rotated and moved up and down by rotation driving means and lifting means (not shown). The table 50 has a circular cross-section on its upper surface, and is formed in a smaller diameter from upper to lower. First recess 52 formed
The receiving member 52 having a, the second recess 52b, and the third recess 52c is fixed, and the core attaching / detaching member 5 is provided inside the third recess 52c.
4 are arranged. Note that, in FIG. 5, for convenience of illustration, the table 50 and the lower portion of the receiving member 52 are omitted, and the core attaching / detaching member 54 disposed inside the third recess 52c of the receiving member 52 is shown. It is shown below the receiving member 52.

The core attachment / detachment member 54 includes a cylindrical base portion 54a having an inclined surface that expands to a large diameter toward the bottom, a disc-shaped core attachment / detachment plate 54b provided above the base portion 54a, and an upper surface of the base portion 54a and a core. It consists of a neck portion 54c that connects the lower surface of the detachable plate 54b,
A projecting pin 54d that fits into the above-mentioned mounting / dismounting hole 22i is projectingly provided on the upper surface of the core attaching / detaching plate 54b, and at the position corresponding to the protrusion 18a of the core supporting rod 18 on the peripheral surface of the core attaching / detaching plate 54b Protrusions 54e are provided at some places.

The inner diameter of the first recess 52a of the receiving member 52 is lower than the die lower portion 44A.
It is formed slightly larger than the outer diameter of (44B) and the die bottom 44A
The second lower recess 52b of the receiving member 54 is formed such that the inner diameter thereof is slightly larger than the outer diameter of the lower end of the core 22. Core 22
To form a core receiving portion that can be held. The inner diameter of the third recess 52c of the receiving member 54 is slightly larger than the outer diameter of the base 54a of the core attaching / detaching member 54, and the core attaching / detaching member 54 can move up and down in the third recess 52c ( That is, the core attaching / detaching member 54 cannot rotate relative to the receiving member 52 by an engaging member (not shown).

A lower portion of the receiving member 52 is provided with a through hole 52d having a rectangular cross section, and an opening / closing cylinder member 58 supported by a cylinder support plate 56 is provided opposite to the opening of the through hole 52d, Inside the through hole 52d, the cylinder member 5 for attachment / detachment is attached.
8, a pressing member 58b supported on the tip of the piston rod 58a.
Are arranged so that they can move back and forth. The tip of the pressing member 58b is formed in a concave shape corresponding to the inclined surface of the base portion 54a of the core attaching / detaching member 54, and is in contact with the inclined surface of the base portion 54a, so that the pressing member 58b has a through hole 52d. The core attachment / detachment member 54 moves upward when it advances inside, and the core attachment / detachment member 54 moves downward when the pressing member 58b retracts.

Further, as shown in FIG. 5, a notch 52e as a work window is provided on the outer peripheral surface of the upper portion of the receiving member 52 at a position corresponding to the die lower mounting bolt 46, and the receiving member 52 has a cutout 52e. With the die lower portion 44A (44B) placed in the first recess 52a, the die lower portion mounting bolt 46 can be attached and detached.

The table 50, the receiving member 52, and the core attaching / detaching member described above
54, the attachment / detachment cylinder member 58 constitutes the attachment / detachment device B.
And replace the lower die 44A (44B).

First, from the state shown in FIG.
The core supporting rod 18 and the vertical groove 22e of the mounting recess 22c of the core 22 are rotated by rotating the receiving member 52 and the core attaching / detaching member 54 by rotating the receiving member 52.
The protrusion 18a of the core 22 is opposed to the concave portion 2 for attachment / detachment of the core 22.
The notch recess 22J of 2h and the protrusion 54e of the core attaching / detaching member 54 are opposed to each other.

Next, the piston rod 58a of the detachable cylinder member 58
And the core attaching / detaching member 54 is lowered to detach the core 22 from the core support rod 18.

Next, by rotating the table 50, the cutout portion of the receiving member 52.
52e and the die lower part mounting bolt 46 are opposed to each other, and the die lower part mounting bolt 46 is removed. In this state,
Due to the resin inside 31, the lower die 44A (42B) becomes the upper die 42A.
It is attached to (42B).

Next, a die lower part detachment bolt 60 (see FIG. 5) having a diameter slightly larger than the die lower part mounting bolt 46 is used.
2B) is screwed into the through hole in a state where the head of the die lower part detachment bolt 60 is positioned at the notch 52e of the receiving member 52, and then the receiving member 52 is rotated. By doing so, the die lower portion 44A (44B) rotates relative to the die upper portion 42A (42B), so that the attachment state between the die lower portion 44A (44B) and the die upper portion 42A (42B) is released, and the die lower portion 44A (44B) is the top of the die
Leave from 42A (42B).

Next, the table 50 is lowered to move the core 22 on the receiving member 52.
And replace the lower die 44A (44B). By doing so, the core 22 and the die lower portion 44A (44B) can be replaced even if the inner diameter of the inner peripheral surface upper end of the die lower portion 44A (44B) is smaller than the outer diameter of the outer peripheral surface lower end of the core 22. .

Also, the replaced core 22 and lower die 44A (44B)
In the reverse order of the above, core support rod 18 and die upper part 42A (42
Can be attached to B).

(Effect of the Invention) As described above, according to the extrusion molding apparatus equipped with the attaching / detaching device according to the invention of claim (1), the die is detachably divided into an upper die portion and a lower die portion, and the inner circumference of the lower die portion is divided. A die molding surface is provided on the surface, and a mounting / dismounting device for mounting / dismounting the core and the lower part of the die is provided, so by simply replacing the core and the lower part of the die, it is possible to extrude parison of different sizes and the replacement work is easy. Is. In particular,
Since the replacement of the core and the lower part of the die can be performed by a single attaching / detaching device instead of separate attaching / detaching devices,
Therefore, the device can be made compact and simplified.

Further, according to the extrusion molding apparatus provided with the attaching / detaching device according to the invention of claim (2), the outer peripheral surface of the core lower portion has the core molding surface formed at a predetermined inclination angle toward the lower end and the upper end of the core molding surface. The inner peripheral surface of the lower part of the die is composed of a core intermediate surface that connects the lower end of the outer peripheral surface of the upper part of the core. Since it consists of the die intermediate surface that connects the lower end of the peripheral surface, even when the parison of different sizes is extruded, the inclination of the core forming surface and the die forming surface can be changed simply by changing the inclination angle of the core intermediate surface and the die intermediate surface. Since the heights of the core and the lower part of the die can be kept constant while maintaining the corners, the distances between the lower end face of the core and the lower end face of the die lower part and the upper end face of the blow molding device can be kept constant.

Therefore, according to the invention of claim (2), since the extrusion position of the parison with respect to the blow molding device becomes constant, the distance between the extrusion position of the parison and the upper surface of the blow molding device can be set to the minimum, so that the core and It is possible to reduce the loss of the resin when replacing the die, and improve the yield of the resin.

[Brief description of drawings]

1 to 3 show an extrusion molding apparatus according to an embodiment of the present invention. FIGS. 1 and 2 are cross-sectional views of a core and a die, respectively, and FIG. 3 is a cross-sectional view of the entire apparatus. 5 and FIG. 5 show a detaching device for the core and the lower part of the die, FIG. 4 is a sectional view, and FIG. 5 is an exploded perspective view. A: Extrusion molding device B: Attachment / detachment device 22,22A, 22B: Core 22a: Core upper part 22b: Core lower part 22l: Outer peripheral surface upper part (core middle surface) 22m: Outer peripheral surface lower part (core molding surface) ) 26,26A, 26B …… die 42A, 42B …… die upper part 44A, 44B …… die lower part 44e …… inner peripheral surface upper part (die middle surface) 44f …… inner peripheral surface lower part (die forming surface)

Claims (2)

(57) [Scope of utility model registration request] 1. A core lower part having a cylindrical core upper part which is detachably mounted on the main body of the apparatus, and a core molding surface which is continuously and integrally formed from the lower end of the core upper part and which expands in a tapered shape on the outer peripheral surface toward the lower end. And a die provided on the inner peripheral surface surrounding the core, the die having a die molding surface facing the core molding surface and expanding in a taper shape toward the lower end, and the core molding surface and the die molding surface. In the extrusion molding apparatus configured to extrude the parison from between the above, the die is composed of a die upper part and a die lower part that are vertically detachably divided, and the die molding surface is provided on the inner peripheral surface of the die lower part. In addition, an attaching / detaching device for attaching / detaching the core and the lower part of the die is provided. The attaching / detaching device includes a table that can be rotated and moved up and down, and the core provided on the table and detached from the upper surface. And a receiving part for receiving the die lower part, and a recess having a circular cross section in the center of the upper surface, and a working window is formed through the receiving part to remove the mounting bolts for attaching the die lower part to the die upper part. A receiving member, a core attaching / detaching member supported in the concave portion of the receiving member so as to be able to move up and down and relatively non-rotatably, to attach the core to the main body of the apparatus when ascending and detach it when descending, and supported by the receiving member. Drive means for moving up and down the core attachment / detachment member, wherein the receiving member receives the core and the lower part of the die in a state where the table is rotated so that the working window faces the mounting bolt. When the table is raised, the core attaching / detaching member is lowered by the operation of the driving means to separate the core from the main body of the apparatus, and the core is removed via the working window. An extrusion molding apparatus provided with a mounting / demounting device, characterized in that the work for removing the lower part of the die can be performed by removing the mounting bolt. 2. An outer peripheral surface of the core lower portion is a core intermediate surface that connects the core molding surface formed to a lower end with a predetermined inclination angle, and the upper end of the core molding surface and the outer peripheral surface lower end of the core upper portion. The inner peripheral surface of the die lower part has the die molding surface formed at a predetermined inclination angle corresponding to the core molding surface toward the lower end, the upper end of the die molding surface and the inner peripheral surface of the die upper part. An extrusion molding apparatus comprising the attachment / detachment device according to claim 1, comprising a die intermediate surface that connects the lower end.