JP2002234065A - Extrusion molding machine for hollow product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hollow product of higher quality by suppressing an influence of a weld mark. SOLUTION: An extrusion molding machine for the hollow product extrusion molds a hollow pipe P from a downstream end of an annular channel 40 formed between an outer peripheral surface of a core 20 and an inner peripheral surface of a shell 10 provided to surround the periphery of the core 20 by supplying a resin material of a soft/molten state to the channel 40. In this molding machine, a turning motion around an axial center along an extrusion direction is forcibly imparted to the resin material supplied to the channel 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for extruding a hollow article such as a hollow tube or a hollow pipe having a circular or irregular cross section with a resin material such as rubber, synthetic resin or thermoplastic. Specifically, by supplying a molten and softened resin material to an annular flow path defined between the outer peripheral surface of the core and the inner peripheral surface of the shell provided so as to surround the periphery of the core. The present invention relates to an improvement in an apparatus for extruding a hollow article from the downstream end of the annular flow path.

[0002]

2. Description of the Related Art Conventionally, when a hollow tube or a hollow pipe having a circular or irregular cross section is extruded with a resin material such as rubber, synthetic resin, or thermoplastic, it is defined between a core and a shell. An apparatus that supplies a resin material in a softened state by melting into an annular flow path is often used. This type of extrusion molding apparatus can obtain a continuous hollow product by continuously supplying a resin material to an annular flow path, and is particularly suitable for manufacturing a long tube or pipe. is there.

[0003]

By the way, in the above-mentioned extrusion molding apparatus, at least one support member for supporting the core is required inside the annular flow path, so that it is melted and softened. The resin material is once separated by the support member and then welded again, so that a welding mark called a weld mark (or weld portion) is formed on the hollow article. This weld mark is inferior in strength compared to other parts, forms a concave part on the surface, etc.
This has a great effect on the quality of hollow products. In particular,
In recent years, the quality required for hollow articles has become more severe, and it is an important issue how the effect of the weld mark on the quality can be reduced.

However, in the conventional extrusion molding apparatus, a hollow product is extruded while the re-welding position of the resin material remains almost constant. As a result, the above-mentioned weld mark comes to stand out linearly in a mode along the extrusion direction, and the appearance quality of the hollow article cannot be avoided. In addition, since the inferior strength portion is concentrated on the one-way portion of the hollow article, it is hard to say that it is preferable in physical properties.

[0005] In view of the above circumstances, an object of the present invention is to provide an extrusion molding apparatus capable of suppressing the influence of weld marks and obtaining a hollow article of higher quality.

[0006]

According to the present invention, an annular flow path defined between an outer peripheral surface of a core and an inner peripheral surface of a shell surrounding the core is melted and softened. By supplying a resin material in a state, in a device that extrudes a hollow article from the downstream end of the annular flow path,
The resin material supplied to the annular flow path is forcibly given a swiveling motion about the axis along the extrusion direction.

[0007] In order to forcibly give the resin material a swiveling motion about the axis along the extrusion direction, for example, the shell is fixedly arranged, and at least the outer peripheral portion of the core which is in contact with the resin material is rotated. What is necessary is just to arrange | position as possible and supply a resin material to the said annular flow path in the state which rotated this outer peripheral part. In this case, as the core, a fixed shaft held on a predetermined fixed body on the upstream end side of the annular flow path, an outer peripheral cylindrical member rotatably disposed on an outer peripheral portion of the fixed shaft, and the fixed A nipple attached to the shaft at a position closer to the downstream end than the outer peripheral cylindrical member, and sequentially rotating the outer peripheral cylindrical member and the stationary nipple with respect to the resin material supplied to the annular flow path. It is preferred that they come into contact. Further, a spiral groove may be provided in a portion serving as a rotary seal portion with the outer peripheral cylindrical member so that when the outer cylindrical member rotates, the spiral groove advances toward the annular flow path. In this case, it is preferable that a plurality of the spiral grooves be provided, and that a means for supplying a resin material from the periphery of the spiral groove be provided. A thrust bearing may be interposed between the fixed shaft and the outer peripheral cylindrical member. Preferably, at least one of the outer peripheral surface of the core and the inner peripheral surface of the shell is provided with a means for increasing a coefficient of friction with a resin material.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing embodiments. FIGS. 1 to 3 show an embodiment of an extrusion molding apparatus according to the present invention, which is an extrusion molding in which a hollow pipe P having a circular cross section is extruded from a resin material such as rubber, synthetic resin or thermoplastic. 1 illustrates an apparatus.

The extrusion head 1 of this extrusion molding apparatus includes:
It is a portion for molding a resin material supplied from an extruder 2 of an appropriate type such as a screw type or a ram type into a desired cross-sectional shape. The head body 110, the die holder 120, the die 130, and the core 20 is provided with a resin distribution member 210, a fixed shaft 220, a nipple 230, and an outer cylinder member 240.

The head body 110 is a cylindrical reference member, and has an annular high friction collar 1 on the inner peripheral surface of the center hole.
40 is held. The high friction collar 140 is provided with a number of outer projections 141 all around the inner peripheral surface. As shown in FIGS. 2 and 3, each of the outer peripheral side projections 141 has a gentle slope portion 142 that projects from the inner peripheral surface of the high friction collar 140 to the inner peripheral side with a very gentle inclination.
It is a portion surrounded by a steep slope portion 143 protruding toward the inner peripheral side so as to rise sharply from the inner peripheral surface of the high friction collar 140. These outer peripheral side protrusions 141 are provided on the gentle slope portion 14.
A ridge 144 serving as an association portion between the second and steep slope portions 143 extends along the axis of the high friction collar 140, and the respective slope portions 142 and 143 have the same direction along the circumferential direction. Are juxtaposed to each other.

The die holder 120 and the die 130 each have an annular shape, and are attached to the tip end of the head body 110 in such a manner that each inner peripheral surface is continuous with the above-mentioned inner peripheral surface of the high friction collar 140. As is apparent from the figure, the continuous inner peripheral surface formed by the high friction collar 140, the die holder 120, and the die 130 has a tapered shape in which the inner diameter gradually decreases toward the tip, and finally the die The innermost peripheral surface of 130 is configured to define the outer diameter of the hollow pipe P to be formed.

Reference numeral 111 in FIG.
10 is a water jacket for circulating warm water inside the wall of No. 10. Reference numeral 150 in the figure denotes the head main body 1.
This is an adjustment bolt for adjusting the positions of the die holder 120 and the die 130 with respect to the die 10.

The resin distribution member 210 has a cylindrical resin receiving part 211 and a flange part 212 extending from the outer periphery of the base end of the resin receiving part 211. The resin flow dividing member 210 inserts the resin receiving portion 211 into the center hole of the head main body 110, and furthermore, the head main body 1 with the flange portion 212 covering the base end surface of the head main body 110.
It is attached to 10. As is clear from the figure, the resin receiving portion 211 of the resin diverting member 210 has a base end fitted into the center hole of the head main body 110 and a distal end separated from the inner peripheral surface of the center hole. It is in.

The fixed shaft 220 is a long shaft-shaped member that penetrates through the center hole of the resin dividing member 210 from a position closer to the base end than the resin dividing member 210, and whose leading end reaches the center hole of the die holder 120. The fixed shaft 220 has its base end screwed to a cover member 250 attached to the resin distribution member 210, so that movement and rotation with respect to the resin distribution member 210 are prevented.

The nipple 230 is a fixing member attached to the distal end of the fixed shaft 220. This nipple 230
The outer diameter of the hollow pipe P is tapered such that the outer diameter gradually decreases toward the tip, and the outermost surface of the taper defines the inner diameter of the hollow pipe P to be formed.

The outer cylinder member 240 is connected to the fixed shaft 220 described above.
Is a tubular member provided so as to surround the outer periphery of the three bearings 26 interposed between the cylindrical member and the fixed shaft 220.
With 0, 261, 262, it is possible to rotate around the axis of the fixed shaft 220. Outer cylinder member 240 and fixed shaft 2
The thrust bearing 262 is applied to the one located closest to the base end among the bearings interposed between the thrust bearing 262 and the bearing 20.

A large number of inner peripheral projections 241 are provided on the entire outer peripheral surface of the outer cylindrical member 240 at a position facing the inner peripheral surface of the high friction collar 140 described above. As shown in FIGS. 2 and 3, each of the inner peripheral side projections 241 has a gentle slope portion 242 projecting from the outer peripheral surface of the outer cylindrical member 240 to the outer peripheral side with a very gentle inclination, and an outer cylindrical member 24.
0 is a portion surrounded by a steep slope portion 243 protruding toward the outer peripheral side so as to rise sharply from the outer peripheral surface. These inner peripheral side projections 241 are formed by a gentle slope portion 242 and a steep slope portion 24.
A ridge line 244 serving as a meeting portion with the outer cylinder member 240 extends along the axis of the outer cylinder member 240, and each steep slope portion 243 is formed on the high friction collar 140 by the steep slope portion 1 of the outer peripheral side projection 141.
43 are arranged side by side so as to face each other.

A driven pulley 270 is provided on the outer cylinder member 240. The driven pulley 270
The cover member 2 is attached to a portion of the resin distribution member 210 which is located on the base end side with respect to the flange portion 212.
It is possible to rotate together with the outer cylinder member 240 inside the inside 50. A drive motor 273 is connected to the driven pulley 270 via a timing belt 271 and a drive pulley 272. Drive motor 27
Numeral 3 is a variable speed type whose rotation speed can be arbitrarily changed.
72, timing belt 271, driven pulley 270
Through the outer cylinder member 240 described above in one direction (for example,
The rotation is performed in the direction indicated by arrow A in FIG. 3).

On the other hand, non-contact type sealing means 30 and 31 using helical grooves are formed at portions that become rotary seal portions with respect to the outer cylinder member 240. Specifically, between the inner peripheral surface of the distal end portion of the outer cylinder member 240 and the outer peripheral surface of the distal end portion of the fixed shaft 220, a spiral groove 300 is engraved on the fixed shaft 220 side so as to seal (hereinafter, referred to as the Side sealing means 30), while the resin dividing member 2
Between the inner peripheral surface of the center hole in 10 and the outer peripheral surface of the outer cylindrical member 240, a spiral groove 310 is formed on the outer cylindrical member 240 side to form a sealing means (hereinafter referred to as a base-side sealing means 31 as appropriate). ). Each sealing means 3
A plurality of spiral grooves 300 and 310 constituting 0 and 31, respectively, are provided so that when the outer cylinder member 240 rotates in the above-described one direction A, the spiral grooves 300 and 310 advance toward the distal end side.

The sealing means 30 and 31 have supply holes 301 and 311 and discharge holes 302 and 3 for resin material, respectively.
12 is attached. In the distal end side sealing means 30, a plurality of holes are radially formed in the outer cylindrical member 240 at positions opposed to the intermediate portion of the spiral groove 300 provided on the fixed shaft 220 along the radial direction, so that the supply holes 3 are formed.
And the discharge shaft 302 is formed by radially piercing a plurality of holes in the fixed shaft 220 at positions located on the base end side of the spiral groove 300 along the radial direction. I have. Base end side sealing means 3
In 1, a plurality of holes are radially formed in the resin receiving portion 211 of the resin distribution member 210 at positions opposed to an intermediate portion of the spiral groove 310 provided in the outer cylinder member 240 in a radial direction, thereby supplying the resin. The discharge hole 312 is formed by forming a plurality of holes radially so as to open the base end surface of the flange portion 212 from a portion located at the base end of the spiral groove 310 in the resin flow dividing member 210. Is configured.

In the extrusion head 1 configured as described above, the inner peripheral surfaces of the head main body 110, the die holder 120, and the die 130, which constitute the shell 10, and the core 2
0, between the resin receiving portion 211 of the resin distribution member 210, the fixed shaft 220, the nipple 230, and the outer peripheral surface of the outer cylinder member 240, the base end is closed and the annular flow is opened toward the front end. The passage 40 is formed, and the annular passage 40 is connected to the extruder 2 via the relay head 50. The relay head 50 communicates with the annular flow passage 40 through a communication passage 112 provided at a portion of the outer peripheral portion of the head main body 110 facing the resin receiving portion 211 of the resin flow dividing member 210, and extends radially outward from the head main body 110. It is an extending part. The extruder 2 sequentially supplies the resin material in a softened state that is melted by the rotation of the screw 2 a to the relay head 50. The above-described head body 110
Similarly, a water jacket 51 for circulating warm water is provided inside the wall of the relay head 50. Reference numeral 52 in the drawing denotes a breaker plate provided in the resin passage of the relay head 50.

In order to form the hollow pipe P in the extrusion molding apparatus constructed as described above, the above-described drive motor 2 is used.
73 is driven to keep the outer cylinder member 240 of the core 20 rotated in one direction A at a constant speed. When the extruder 2 is driven from this state, the resin material supplied to the relay head 50 reaches the annular flow passage 40 through the communication passage 112. The resin material that has reached the annular flow path 40 sequentially advances inside the annular flow path 40 toward the tip side of the extrusion molding head 1, and finally reaches the die 130 and the nipple 230.
And the hollow pipe P having the desired shape is continuously extruded.

Here, the resin material that has reached the annular flow path 40 through the relay head 50 is once separated by the resin receiving portion 211 of the resin distribution member 210, and is then welded again to fill the annular flow path 40. Therefore, even in the extrusion molding apparatus described above, a weld mark, which is a welding mark, is formed at a position shifted from the relay head 50 by approximately 180 °.

However, according to the extrusion molding apparatus, the outer peripheral member 240 is continuously rotated while the resin material is being supplied, and the inner peripheral side protrusion which increases the friction coefficient on the outer cylindrical member 240 is provided. 241 is provided, so that the resin material in contact with the core 241 does not slip.
The vehicle travels along the annular flow path 40 while turning around the zero axis. As a result, the weld marks generated by the re-welding of the resin material are spirally distributed widely over the entire circumference of the hollow pipe P and appear in a blurred state on the surface, thereby suppressing the deterioration of the appearance quality. Will be able to
In addition, even in terms of strength, a portion of a weld mark having a low strength does not concentrate on a specific portion as in the past, and the physical properties are more preferable.

The spiral of the weld line distributed over the entire circumference of the hollow pipe P is adjusted by appropriately adjusting the rotation speed of the outer cylinder member 240 by the drive motor 273 with respect to the extrusion speed of the resin material by the extruder 2. The width can be arbitrarily adjusted. Therefore, for example, if the rotation speed of the outer cylinder member 240 by the drive motor 273 is set to be larger than the extrusion speed of the resin material by the extruder 2, the spiral of the weld line appearing on the surface becomes finer and the appearance is strong. It is possible to obtain a higher quality hollow pipe P.

Further, in the above-mentioned extrusion molding apparatus, since the outer peripheral side projection 141 is provided on the high friction collar 140 so as to oppose the inner peripheral side projection 241 provided on the outer cylinder member 240, the projection 141 and 241 cooperate with each other. By the action, it is possible to expect the stirring of the resin material traveling in the annular flow path 40 within the plate thickness, and the above-described operation and effect becomes more remarkable.

In the above extrusion molding apparatus, a rotary seal is formed inside the annular flow passage 40 by rotating the outer cylindrical member 240, but the spiral grooves 300 and 310 are respectively provided. Sealing means 30,
Since the rotary member 31 is provided, there is no possibility that the resin material leaks from the rotary seal portion to the outside of the annular flow path 40. That is,
The resin material that has reached the rotating seal portion is the rotating outer cylinder member 2.
Since the fluid is pushed back to the annular flow path 40 by the action of the spiral groove 300 and the spiral groove 300, 310, there is no possibility of leakage to the outside through the rotary seal portion. Even if the resin material advances to the inner part of the rotary seal portion, the resin material is removed from the rotary seal portion through the individually provided discharge holes 302 and 312 and the resin supplied from the individually provided supply holes 301 and 311. The material is pushed out to the annular flow path 40. Therefore, there is no fear that the resin material remains in the rotary seal portion and is directly deteriorated or seized.
In this case, the spiral grooves 300,
When a plurality of the grooves 310 are provided, the resin material supplied from the supply holes 301 and 311 becomes intermittent with respect to the spiral grooves 300 and 310, and the extrusion of the resin material into the annular flow path 40 becomes more effective. Deterioration and seizure of the resin material at the rotary seal portion can be more reliably prevented.

Further, in the above-mentioned extrusion molding apparatus, the resin material immediately before being finally extruded and formed as a hollow pipe P from the extrusion molding head 1 is brought into contact with the nipple 230 and the die 130 in a stationary state. I have.
In addition, the rotating outer cylinder member 240 and the fixed shaft 2
Since the thrust bearing 262 is interposed between the outer cylindrical member 240 and the outer cylinder member 20, it is possible to prevent the outer cylinder member 240 from moving in the thrust direction due to the pressure of the resin material from the extruder 2 as much as possible. As a result, the dimensional accuracy of the hollow pipe P can be improved, and the quality can be further improved.

In the above-described embodiment, an apparatus for extruding a circular hollow pipe is exemplified. However, the present invention can be applied to an apparatus for extruding a hollow article having another shape. is there. In this case, at the downstream end of the annular flow path, the cross-sectional shape needs to match the shape of the hollow article to be molded, but the portion that gives the resin material a swivel motion does not necessarily have to have the shape of the hollow article. It is not necessary that they match, and it is preferable that they form a ring.

Further, in the above-described embodiment, the extruder is connected to the outer periphery of the extrusion head. However, the present invention is not limited to this. Even if an extruder is connected to the side, the same effect can be expected.

Further, in the above-described embodiment, the resin material is caused to pivot by rotating only the core. However, only the shell may be rotated, or both the shell and the core may be rotated together. It does not matter. In addition, the turning motion given to the resin material is not limited to rotating in one direction at a constant speed, and the speed and direction may be changed at random. Further, although the power from the drive source is transmitted by the timing belt, it goes without saying that a gear train or a chain may be applied instead of the timing belt.

[0032]

As described above, according to the present invention,
Since the swirling motion about the axis along the extrusion direction is forcibly applied to the resin material supplied to the annular flow path, the weld marks are widely dispersed and blurred on the surface of the hollow product. As a result, the appearance quality can be prevented from deteriorating. In addition, a portion having low strength does not concentrate on a specific portion, and the physical properties are more favorable.

[Brief description of the drawings]

FIG. 1 is a cross-sectional side view of a main part showing an embodiment of an extrusion molding apparatus according to the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is an enlarged sectional view taken along line III-III in FIG. 2;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 extrusion head 2 extruder 10 shell 20 core 30 distal sealing means 31 proximal sealing means 40 annular flow path 50 relay head 110 head body 112 communication passage 120 die holder 130 die 140 high friction collar 141 outer peripheral projection 210 resin Dividing member 211 Resin receiving part 212 Flange part 220 Fixed shaft 230 Nipple 240 Outer cylinder member 241 Inner peripheral side projection 250 Cover member 262 Thrust bearing 270 Driven pulley 271 Timing belt 272 Drive pulley 273 Drive motor 300, 310 Spiral groove 301, 311 Supply Hole 302,312 Discharge hole P Hollow pipe

Claims (8)

[Claims] 1. A molten and softened resin material is supplied to an annular flow path defined between an outer peripheral surface of a core and an inner peripheral surface of a shell provided so as to surround the core. In the apparatus, the hollow article is extruded and formed from the downstream end of the annular flow path, and the resin material supplied to the annular flow path is forcibly pivoted about the axis along the extrusion direction. An extrusion molding apparatus for hollow articles, wherein 2. A fixed arrangement of the shell, wherein at least an outer peripheral portion of the core in contact with the resin material is rotatably disposed, and the resin material is supplied to the annular flow path with the outer peripheral portion rotated. The extrusion apparatus for hollow articles according to claim 1, wherein 3. A fixed shaft held by a predetermined fixed body on an upstream end side of the annular flow path, an outer peripheral cylindrical member rotatably disposed on an outer peripheral portion of the fixed shaft, A nipple attached to a position on the downstream end side of the outer peripheral cylinder member with respect to the fixed shaft, the outer peripheral cylinder member being rotated and the nipple being stationary with respect to the resin material supplied to the annular flow path. 2. The method according to claim 1, wherein the contact is performed sequentially.
Or the extrusion molding apparatus for hollow articles according to claim 2. 4. The helical groove according to claim 3, wherein a helical groove is provided at a portion serving as a rotary seal portion with the outer peripheral cylindrical member so that the helical groove advances toward the annular flow path when the outer cylindrical member rotates. Extrusion molding equipment for hollow products. 5. The apparatus for extruding a hollow article according to claim 4, wherein a plurality of said spiral grooves are provided. 6. The apparatus for extruding a hollow product according to claim 4, further comprising means for supplying a resin material to the spiral groove from the periphery thereof. 7. The apparatus according to claim 3, wherein a thrust bearing is interposed between the fixed shaft and the outer cylindrical member. 8. The hollow according to claim 1, wherein at least one of an outer peripheral surface of the core and an inner peripheral surface of the shell is provided with a means for increasing a coefficient of friction with a resin material. Extrusion molding equipment.