JP2003276084A - Method and apparatus for molding cylindrical molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for molding a cylindrical molded article capable of molding a cylindrical molded product equipped with a molding part having an undercut part on one part of an inner surface in high precision and in high appearance. <P>SOLUTION: The apparatus for molding a cylindrical molded article comprises a core mold 2 of which the maximum outer diameter is the almost same diameter as an inner diameter of a resin pipe while an outer peripheral surface of the almost same vertical sectional irregular shape as a vertical irregular shape of a port inner surface is provided; an outer mold 3 having a molding surface of an outer surface shape of the port and comprising a plurality of divided molds 31 so that the port part can be taken out in separating by being freely assembled so as to surround a working part 55 of the resin pipe 5a from outside; a core mold-eccentrically revolving mechanism 4 wherein the core mold 2 is revolved around a central axis of the port under a condition of being parallel and eccentric to the central axis of the molding part and the working part 55 is compressed in an outer mold direction; and a thick wall part molding apparatus wherein a necessary length of an end part of a cylindrical molding material is heated at ≥ a crystallization temperature and ≤ a melting temperature and a thick wall part corresponding to the molding part is molded by pushing the end part to a main body side revolving the cylindrical molded material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for molding a tubular molded product.

[0002]

2. Description of the Related Art As a method for forming a receiving port at the end of a resin pipe material, the following method has been conventionally performed.

(1) A method of press-fitting a mold having an outer surface conforming to the inner surface shape of the receiving port (sleeve method) into a receiving port forming portion such as a resin pipe as a cylindrical molding material (2) tubular molding material After the core mold is inserted into the resin pipe as described above, a part of the core mold (shell) is hydraulically moved so as to be spread outward to expand the diameter of the pipe and form a so-called petal core ( (Expansion method of shell diameter by hydraulic pressure) (3) JP-A-7-1580 and JP-A-7-1582
As disclosed in Japanese Unexamined Patent Publication (Kokai), etc., a core mold is inserted into a resin pipe serving as a cylindrical molding material, and then a part (shell) of the core mold is mechanically moved so as to be spread outward and the pipe is moved. A method of using a so-called petal core to expand the diameter of the shell and to form the socket (shell diameter expansion method by mechanical action) (4) After molding a molded product of the socket-like shape with no undercut portion by injection molding, A method of forming an undercut portion by cutting a molded product similar to a socket to obtain a socket (5) A method of cutting a thick pipe or a cylindrical rod extruded into a socket shape The conventional methods as described above have the following problems, respectively.

In the case of the above method (1), the mold structure is simple, but a large force is required when the core mold is press-fitted or withdrawn. Moreover, when the receiving opening has a large concave and convex undercut portion such as a fitting groove of a rubber ring, there is a possibility that the core mold may not come off from the molded product after molding.

In the case of the above method (2), since the shell moves in the diameter expanding direction and comes into close contact with the inner surface of the resin pipe, a mold mark remains on the inner surface of the obtained receiving portion, resulting in poor appearance. Also, there is a risk that the rubber ring for sealing fitted inside the receptacle may be improperly mounted. In addition, due to the structure of the shell, when a holding pressure is applied after filling, it is difficult to apply a large holding pressure because the device may be broken.

In the case of the above method (3), the shell diameter-expanding mechanism is complicated and the number of parts is large, which is likely to cause a failure. Further, since the structure of the mold is complicated, it is not suitable for molding a small diameter one, and the manufacturing cost of the mold becomes high.

In the case of the above methods (4) and (5), the receptacle can be molded with high accuracy, but the processing cost is high.
Further, it is difficult to cut the end portion of the straight pipe, and first, a method of adhering or fusing the joint obtained by the cutting work to the end portion of the straight pipe must be taken, which increases the cost of the secondary processing.

[0008]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a cylindrical molded article having a simple structure of a molding apparatus and provided with a molding portion having an undercut portion on at least a part of the inner surface thereof. An object of the present invention is to provide a method for molding a tubular molded product and a molding apparatus for the same, which can be molded with high precision and high appearance.

[0009]

In order to achieve such an object, a method for molding a tubular molded product according to a first aspect of the present invention is a tubular product having a molding portion having an undercut portion in at least a part thereof. A molding method for a molded product, wherein a core die having an outer surface shape substantially corresponding to the inner surface shape of the molding portion is formed in the axial direction of the core die at a processing portion of a tubular molding material having an inner diameter larger than the maximum diameter portion of the core die. Core mold insertion step of relatively moving and inserting into the core molding material, a molding material heating step of heating at least the processed portion of the tubular molding material to make it easily deformable, and fixing the tubular molding material to the center of the core mold. The shaft is revolved around the central axis of the molding part to be molded while eccentric while keeping the shaft parallel to the central axis of the molding part to be molded, and the processed part is cylindrically molded on the outer surface of the core mold. Forming the forming part while compressing in the outer peripheral direction of the material It comprises a molding step and a mold releasing step in which a tubular molded product having a molded part molded therein is relatively moved in the axial direction of the core mold and released from the mold. For a required length at a temperature above the crystallization temperature and below the melting point temperature, and by pressing this end into the main body side while rotating this tubular molding material, a thick wall portion that matches the molding portion is formed. It is characterized in that it includes a part forming step.

According to a second aspect of the present invention, there is provided a molding device for a cylindrical molded product, which has an outer surface shape substantially corresponding to an inner surface shape of a molding portion including an undercut portion provided in the cylindrical molded product to be molded. While maintaining the core die whose maximum outer diameter is smaller than the inner diameter of the tubular molding material, the fixing means for fixing the tubular molding material, and the central axis of the core die parallel to the central axis of the molding part to be molded. A core die eccentric revolution mechanism for revolving the core die around the center axis of the molding part to be eccentric and compressing it in the outer peripheral direction of the tubular molding material on the outer surface of the core die, and an end portion of the tubular molding material A thick-walled portion forming device that preliminarily forms a thick-walled portion corresponding to the molding portion, the thick-walled portion forming device includes a rotation support means that rotatably supports the main body of the tubular molding material, and a tubular molding Heating means for heating one end of the material by a required length,
It is provided with a pushing means for pushing one end portion toward the body portion side, and a pre-shaping means for pre-shaping the one end portion pushed by the pushing means into a shape corresponding to the molding portion.

In the apparatus for molding a tubular molded product according to a third aspect of the present invention, the fixing means can be assembled so as to surround the processed portion of the cylindrical molding material to be the molding portion from the outside, and the molding portion can be divided at the time of division. Is an outer mold having a plurality of split dies that are removably divided and at least having an inner surface shape substantially corresponding to the outer surface shape of the molding portion.

As the material of the molding material used in the molding method of the present invention, a resin having a high degree of crystallinity and a high shrinkability such as high-density polyethylene is suitable, but a non-crystalline resin such as vinyl chloride resin or polystyrene is preferable. Resins can also be used.

In the present invention, the term "cylindrical" means not only a cylindrical shape having a perfect circular cross section, but also an oval shape or an elliptical shape, and various shapes on the surface. The convex portion may be provided so as to project.

In the molding method of the present invention, the molding material heating step may be performed before or after inserting the core mold into the processing portion.

The easily deformable state means a state in which the processed portion is easily deformed by the eccentric revolution of the core type, and the heating temperature at this time is equal to or higher than the softening point temperature of the material forming the tubular molding material. Is preferable, and particularly preferably crystallization temperature or higher and melting point temperature or lower.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
A detailed description will be given with reference to the drawings.

FIG. 1 shows an embodiment of a molding apparatus for a cylindrical molded product according to the present invention.

As shown in FIG. 1, the molding apparatus 1 comprises a core mold 2, an outer mold 3, and a core mold eccentric revolution mechanism 4.
As a cylindrical molded product, a ring-shaped groove 52 for a rubber ring, into which a sealing rubber ring (not shown) as shown in FIG.
It is possible to mold a straight pipe 5 with a single socket having 1 as a molding portion.

The core mold 2 has a cylindrical shape whose outer surface 21 has a vertical cross-section uneven shape which is substantially the same as the vertical cross-sectional uneven shape of the inner surface of the receptacle 51, and the core type eccentric mechanism 4 is described in detail later. The shaft main body 452 is inserted from one end, and is rotatable about the central axis of the core mold 2 via the bearing 6 fitted onto the shaft main body 452. In addition, the core mold 2 has a resin pipe 5a that has a maximum diameter and is a tubular molding material and is extruded in advance.
The diameter is slightly smaller than the inner diameter of.

The outer mold 3 is provided with two split molds 31, 31 and a support plate 32 which are divided along the axis thereof, and has an inner surface shape along the outer peripheral surface of the receiving port 51 which is a molding portion. The minimum diameter is approximately the same as the outer diameter of the resin pipe 5a. Further, the support plate 32 supports the split molds 31, 31 so as to be movable in and out of contact with each other, and has a through hole 33 for a shaft main body 452, which will be described later, formed in the center thereof.

Further, the outer mold 3 is provided with a heater 34 and a cooling pipe 35 through which the refrigerant passes along the molding surface thereof.

As shown in FIG. 1, the core type eccentric revolution mechanism 4
Includes a casing 41, a rotating case 42, a forward / backward member (push / pull angular contact) 43, a slide block (eccentric angular contact) 44, and a shaft portion 45 that rotatably supports the core die 2. The rotating case 42 is supported by a bearing 46 and is rotatable in the casing 41, and a sprocket 47 is fitted onto the rotating case 42.

The rotary case 42 is rotated in the casing 41 by transmitting the rotational driving force of the electric motor 48 through the gear 481, the chain 49 and the sprocket 47 provided on the rotary shaft of the electric motor 48. There is.

The advancing / retreating member 43 has a substantially oval cross section, is slidably inserted in the rotating case 42 in the direction of the core mold, and its rear end rotates to the rod tip of a hydraulic cylinder (not shown). It is freely supported, and rotates with the rotation of the rotating case 42, and moves back and forth inside the rotating case 42 in the core mold 2 direction by the expansion and contraction of the rod of the hydraulic cylinder.

Further, the advancing / retreating member 43 is provided with an angular pin 431, which has a rectangular cross section and is inclined with respect to the slide shaft of the advancing / retreating member 43, on the surface on the core die 2 side.

On the other hand, the slide block 44 comprises the core type 2
A connecting pin 441 connected to a shaft portion 45 described later on the side surface.
And has an angular hole 442 that has the same cross-sectional shape as the angular pin 431 and is inclined at the same angle on the surface of the advancing and retracting member 43
The angular pin 431 is slidably inserted into the angular hole 442.

That is, the slide block 44 is moved forward and backward by the advancing / retreating member 43 in the core mold 2 direction,
The angular pin 431 moves back and forth in the angular hole 442. Moreover, since the angular hole 442 and the angular pin 431 are provided so as to be inclined with respect to the advancing / retreating direction of the advancing / retreating member 43, the central axis of the angular pin 431 is moved by the advancing / retreating of the angular pin 431 into the angular axis of the core die 2a. It slides in the rotating case 42 in a direction orthogonal to the direction. Further, the advancing / retreating member 43 is the rotating case 4
When it rotates with the rotation of 2, the rotational force is transmitted to the slide block 44 via the angular pin 431, and the slide block 44 also rotates together with the advancing / retreating member 43.

The shaft portion 45 includes a base portion 451 and a shaft portion main body 4
52 and the base pin 451 has its central axis aligned with the central axis of the slide block 44.
It is fixed through 41.

The shaft main body 452 is inserted into the core mold 2a while facing the inside of the outer mold 3 through the insertion hole 33 formed in the support plate 32, and the core mold 2a is attached and detached via the bearing 6. It is supported freely and the shaft body 45
It is rotatable around 2.

A heater 453 for heating the core mold 2 and a cooling water cooling pipe 454 for cooling the core mold 2a are provided in the shaft body 452.

The advancing / retreating member 43 and the slide block 4
The material of No. 4 is not particularly limited, but it is preferable that at least the portion forming the contact portion of the advancing / retreating member 43 and the slide block 44 is made of a material having impact resistance, dust resistance, etc. From maraging steel, chrome-molybdenum steel (SMC steel) and tool steel (SK
D steel) is more preferable. Further, in consideration of abrasion resistance and low friction, it is more preferable to perform surface heat treatment such as vacuum quenching and tuftride.

Further, the molding apparatus 1 configured as described above
Is provided with a thick portion forming device for preliminarily shaping the processed portion of the tubular molding material into a thick portion suitable for the molding portion.

FIG. 3 shows the construction of the thick portion forming device.

This thick-walled portion forming device 7 has a rotation supporting means 71 for rotatably supporting a resin pipe 5a which is a cylindrical molding material, and a heating means 72 for heating one end 551 of the resin pipe 5a by a required length. And a pushing means 73 for pushing one end portion toward the main body portion 552 side, and a preliminary shaping means 74 for preliminarily shaping the one end portion 551 into the processing portion 55 having a shape corresponding to the molding portion in cooperation with the pushing action by the pushing means 73. ing.

The rotation supporting means 71 includes a holding member 711 for holding the main body 552 of the resin pipe 5a, and the holding member 7.
11 and a driving device 714 that rotationally drives the resin pipe 5a.

The holding member 711 is formed with a holding hole 712 at the center thereof, through which the resin pipe 5a can be inserted. The holding member 711 has its one end portion centered so that the resin pipe 5a can be arranged in the holding hole 712. It is composed of two split members that are openably and closably connected. A plurality (two in the figure) of the holding members 711 are provided according to the length of the main body 552 of the resin pipe 5a, and are attached to the apparatus main body via the attachment member 713.

The driving device 714 is for rotating the resin pipe 5a held by the holding member 711 in a fixed direction, and a supporting roller 715 for supporting the lower portion of the resin pipe 5a.
And a drive motor 716 that rotationally drives the support roller 715. Specifically, the support roller 715
Rotary shaft 715a and output shaft 716a of drive motor 716
Are connected by a transmission means composed of pulleys 717a and 717b and a belt 717c. By rotating the supporting roller 715 by the drive motor 716, the supporting member 7
11, the resin pipe 5a loosely fitted and held in the holding hole 712.
I am trying to rotate.

The heating means 72 has a built-in heater, and has a heater shaft 721 inserted into one end 551 of the resin pipe 5a by a required length, and an external heater arranged on the outer peripheral surface of the one end 551 of the resin pipe 5a. And 722.

The heater shaft 721 and the external heater 722 are
The one end portion 551 of the resin pipe 5a is heated from the inner surface side and the outer side, and specifically, it is preferable to heat the one end portion 551 at the crystallization temperature or higher and the melting point temperature or lower.

The pushing means 73 is formed in a tubular body having a flange portion 731 that comes into contact with the one end 551 of the resin pipe 5a when the one end 551 of the resin pipe 5a is inserted and arranged in the heater shaft 721. The heater shaft 721 is slidably fitted in the outer peripheral surface of the heater shaft 721 in the axial direction of the heater shaft 721. A telescopic rod end 733 of the telescopic cylinder 732 is connected to the pushing means 73, and the telescopic operation of the telescopic cylinder 732 causes the pushing means 73 to move in the axial direction along the outer peripheral surface of the heater shaft 721 via a guide rail (not shown). The end portion 551 of the resin pipe 5a is pushed into the main body portion 552 side by the flange portion 731 by sliding the end portion 551 to the main body portion 552 side.

The pre-shape forming means 74 is a horizontal roller 741 arranged in parallel with the resin pipe 5a with a predetermined space.
And a tilt roller 742, which is provided on one end side of the horizontal roller 741 on the main body 552 side of the resin pipe 5a and has its axis inclined.

These horizontal roller 741 and tilt roller 7
42, when pushing the one end 551 of the resin pipe 5a by the pushing means 73, a proper number of 42 are respectively provided so as to rotatably support the outer peripheral surface of the one end 551 while restricting outward bulging. It is provided so that the shape is preliminarily shaped to match the molding portion.

Next, a case will be described in which the one end portion 551 of the resin pipe 5a is preliminarily thickly shaped by the thick portion forming device 7 having the above-described structure.

First, with the one end 551 of the resin pipe 5a inserted into the heater shaft 721, the resin pipe 5a is
Are held by the holding member 711.

Subsequently, the resin pipe 5a is connected to the driving device 714.
While rotating by the heater shaft 721 and the external heater 72
2, the one end 551 is heated from the inside and the outside at the same time, and the one end 551 is brought to a state of the crystallization temperature or higher and the melting point temperature or lower.

After that, the pushing means 73 is operated to gradually move the one end 551 to the main body 552 side. As a result, the one end portion 551 is gradually thickened from the state shown in FIG. 4A by the inclined roller 742 as shown in FIG. 4B, and finally the inclined roller 742 and the horizontal roller 741 are formed.
By doing so, a processed portion 55 (two-dot chain line in FIG. 3, see also FIG. 5) corresponding to the molding portion as shown in FIG. 4C is formed thickly.

Thus, by heating the inside and the outside simultaneously while rotating the resin pipe 5a, a uniform temperature distribution can be obtained, and the one end 551 is once heated above the crystallization temperature and below the melting temperature. By doing, one end 5
Since the resin structure of 51 is once destroyed and the melting point temperature is lower than the shape-retaining temperature, it is possible to easily preform the outer peripheral surface of the one end portion 551 by the inclined roller 742 and the horizontal roller 741 into a shape corresponding to the molding portion. You can In addition,
The inner peripheral surface of the processed portion 55 is held by the heater shaft 721 in the same inner diameter shape. That is, the heater shaft 721
Also plays a part of the preliminary shaping means 74.

In this way, the resin pipe 5 whose one end 551 is preliminarily shaped on the processed portion 55 having a shape suitable for the molding portion in advance.
For a, it is possible to mold the straight pipe 5 with a single socket having the socket 51 by the molding method described later using the molding apparatus 1.

Next, the molding method of the present invention using this molding apparatus 1 will be described in order of steps with reference to FIGS. 6 and 7.

As shown in FIG. 6 (a), the outer mold 3 has two
The two split dies 31, 31 are separated from each other, and the core die 2a is kept in a state where its central axis coincides with the central axis of the insertion hole 33 of the support plate 32.

The heaters 34 and 453 heat the vicinity of the molding surfaces of the outer mold 3 and the core mold 2 to the easily deformable temperature of the resin pipe 5 a.

One end 551 by the thick portion forming device 7
Is heated to a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point temperature, and the processed portion 55 of the resin pipe 5a in which the one end portion 551 is preliminarily shaped into a thick shape corresponding to the molding portion is fitted onto the core mold 2.

As shown in FIG. 6 (b), the two split dies 31, 31 are closed and assembled by the outer die 3 so as to surround the processed portion 55, and the resin pipe 5 a of the smallest diameter portion of the outer die 3 is formed. Clamp the outer peripheral surface.

As shown in FIG. 6C, the advancing / retreating member 43 is gradually moved toward the core die 2 while rotating the rotating case 42.
The resin pipe 5a is compressed in the mold surface direction of the outer mold 3 while advancing to the a side to eccentric the core mold 2a.

As shown in FIG. 7 (a), while rotating the rotating case 42, the eccentricity of the core mold 2 a is further increased and the core mold 2 a is uniformly compressed with the outer mold 3 over the entire circumference to receive the socket. Mold 51.

After cooling water is passed through the cooling pipes 35 and 454 to cool the outer mold 3 and the core mold 2a to solidify the resin by cooling, the core mold 2a is returned to the neutral position as shown in FIG. 7B. , The outer mold 3 as shown in FIG.
The two split molds 31 and 31 are separated so that the minimum diameter portion thereof is located at a position apart from the maximum outer diameter portion of the receiving opening 51 from the central axis of the receiving opening 51.

As shown in FIG. 7 (c), the straight pipe 5 with a single socket having the socket 51 formed therein is removed in the axial direction of the core mold 2 a and separated. However, it is not necessary to return the core mold 2a to the neutral position as long as it does not hinder the mold release.

The steps of and may be reversed in order.

As described above, the thick portion forming device 7 preliminarily shapes the processed portion 55 into a thick wall having a shape suitable for the molding portion, and the processing portion 55 is molded by the molding device 1 as described above. As shown in FIG. 6B, when the resin pipe 5a is clamped by the outer mold 3, the processing portion 55 is in a state of being substantially in close contact with the outer mold 3 by the pre-molding. Since it can be performed, the processed portion 55 is not excessively expanded. Therefore, the molding time can be shortened, and a molded product having a good appearance without wrinkles can be obtained. Further, it is possible to easily form a deep undercut portion or a receiving portion having a different thickness.

Moreover, since the core die 2 revolves while maintaining the eccentricity, and the peripheral surface of the core die 2 smoothly rolls along the inner surface of the machined portion 55, the resin of the machined portion 55 is moved from the inside to the outside die. Since the resin can be uniformly compressed vertically toward the molding surface of No. 3 to evenly disperse the shrinkage force of the resin, the shape can be corrected and the density can be increased. In other words, even for a molded part with an undercut-shaped receptacle, a cylindrical molded product with uniform density, less warpage, deformation, residual strain, etc. It can be easily integrally molded.

The present invention is not limited to the above embodiment. For example, a single-ended straight pipe having a receiving shape as shown in FIG. 8 can be molded, and the tubular molded product is not limited to the single-ended straight pipe but may be a joint or the like.

[0062]

EXAMPLE A high density polyethylene resin pipe 5a having a nominal diameter of 50 mm (inner diameter 48 mm) as a cylindrical molding material and a molding apparatus 1 as shown in FIG. 1 were prepared, and the rubber ring groove 52 was formed under the following molding conditions. 2 with a socket 51 having an inner surface
The straight pipe 5 with a single socket as shown in (a) was preliminarily shaped by the thick portion forming device 7 and molded. The control of the eccentricity of the core mold 2a was switched by feeding back the value of the temperature sensor.

Heating temperature: 150 ° C. Heating time: 10 minutes Core type eccentric revolution time: 10 minutes Core type eccentricity: 13 mm Core type revolution speed: 25 rpm After processing the pipe with a socket thus obtained, the temperature is 23.
Stored in a room at ℃ for 1 hour after processing A shown in Fig. 2 (a)
(10 mm from the tube end as the starting point), B (25 mm from the tube end as the starting point), C (60 m from the tube end as the starting point)
m) and D (100 mm from the pipe end as a starting point), the inner diameter and the outer diameter are measured at each of 6 points in the circumferential direction shown in FIG. 2B, and the maximum and minimum values of the measured values are measured. The roundness was calculated as the difference.

As a result, although it is slightly inferior to the cut product, as in the case of the polyethylene resin pipe with a single-ended opening in which the receiving portion is molded by conventional injection molding and the straight portion is fused with the receiving portion, The roundness was 0.2 mm.

On the other hand, in the case of a hard vinyl chloride resin pipe with a single socket formed by using a conventional petal core,
The roundness was 0.8 mm.

Furthermore, when the groove 52 for the rubber ring, which is the undercut portion, was cut in the axial direction and the depth of the groove was measured in the cross section, good dimensions were obtained. Also,
The appearance was good with no twists or wrinkles, there were no mold marks, and the transferability was good, and there was no need for secondary processing such as cutting.

[0067]

As described above, according to the method and apparatus for molding a tubular molded article of the present invention, the thick-walled portion forming device preliminarily shapes the processed portion into a thick wall having a shape matching the molded portion. In addition, since the processed portion is molded in this state, the molding time can be shortened and a molded product with good appearance without wrinkles can be obtained. Further, it is possible to easily form a deep undercut portion or a receiving portion having a different thickness.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a molding device for a cylindrical molded product according to the present invention.

2A is a cross-sectional view of a straight pipe with a single socket formed by using the forming apparatus of FIG. 1, and FIG. 2B is a view showing measurement points.

FIG. 3 is a side view showing a configuration of a thick portion forming device.

FIG. 4 is a schematic view showing a process of preforming a thick portion by a thick portion forming device.

FIG. 5 is a perspective view showing the shape of a resin pipe after preliminary shaping.

6A and 6B are explanatory diagrams illustrating a method of molding a tubular molded product using the molding apparatus of FIG. 1 in order of steps.

FIG. 7 is an explanatory diagram for sequentially explaining subsequent steps of the step of FIG.

FIG. 8 is a cross-sectional view showing another example of a tubular molded product molded by the molding method and the molding apparatus of the present invention.

[Explanation of symbols]

1 molding equipment 2 core type 3 External type 31 split type 4 core type eccentric revolution mechanism 5 Straight pipe with single-ended opening (cylindrical molded product) 5a Resin pipe (cylindrical molding material) 51 Receptacle (molding part) 52 Recessed groove for rubber ring (undercut part) 55 Processing Department 551 One end 552 main body 7 Thick wall forming device 71 Rotation support means 72 heating means 73 Pushing means 74 Preliminary shaping means

Claims (3)

[Claims] 1. A method of molding a tubular molded product, comprising a molding part having an undercut part in at least a part thereof, wherein a core mold having an outer surface shape substantially corresponding to the inner surface shape of the molding part is used. A core mold inserting step of relatively moving in the axial direction of the core mold and inserting it into a machined part of a cylindrical molding material larger than the maximum diameter part of the mold, and heating at least the machining part of the cylindrical molding material to make it easily deformable. Molding process to heat the molding material, and to mold the core mold while fixing the cylindrical molding material and eccentric while keeping the central axis of the core mold parallel to the central axis of the molding part to be molded. Molding process in which the molding part is molded while revolving around the central axis of the molding part and compressing the processing part in the outer peripheral direction of the cylindrical molding material on the outer surface of the core mold; Mold release work by releasing the mold by moving it relative to the axial direction of In the molding material heating step, the end portion of the tubular molding material is heated by a required length at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point temperature, and the end portion is heated while rotating the tubular molding material. A method for molding a tubular molded article, comprising: a thick-walled portion forming step of forming a thick-walled portion corresponding to the molded portion by being pushed into the main body side. 2. A core having an outer surface shape substantially corresponding to an inner surface shape of a molding portion including an undercut portion provided in a tubular molding product to be molded, and having a maximum outer diameter smaller than an inner diameter of the cylindrical molding material. The mold, the fixing means for fixing the tubular molding material, and the eccentricity while keeping the central axis of the core mold parallel to the central axis of the molding part to be molded, A core type eccentric revolution mechanism that revolves around the central axis and compresses the outer surface of the core mold in the outer peripheral direction of the tubular molding material, and a thick wall that pre-forms the end of the tubular molding material into a thick part that matches the molding part. A thick part forming device, the thick part forming device includes a rotation supporting means for rotatably supporting the main body of the cylindrical molding material, and a heating means for heating one end of the cylindrical molding material by a required length. , Pushing the one end to the main body side and the pushing means Tubular molded article of a molding apparatus characterized by comprising a preliminary shaping means for pre-shaped into a shape commensurate with the molding portion Murrell end. 3. The fixing means is free to assemble so as to surround a processed portion of a cylindrical molding material, which is a molding portion, from the outside,
3. The outer die, which comprises a plurality of split dies in which the molding portion is removably divided at the time of division, and which has an inner surface shape at least approximately corresponding to the outer surface shape of the molding portion.
Molding device for the cylindrical molded article described.