JPH0688302B2 - Method and apparatus for forming a flexible tube in which protrusions are spirally provided on the inner surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is a flexible structure in which a ridge is provided in a spiral shape on the inner surface of an electric wire protection tube or the like used to protect cables such as electric wires and optical fibers. The present invention relates to a method for molding a pipe and a molding apparatus therefor.

(Prior Art) A corrugated pipe has been conventionally known as a synthetic resin pipe which is considered to have spiral ridges of a round or polygonal shape arranged on the inner surface.

This corrugated pipe is expanded by the compressed air ejected from the air holes of the cylindrical melt extruded from the double pipe land part, and is sent by the caterpillar that circulates outside the double pipe land part. A corrugated pipe (wrinkled pipe) is continuously molded by crimping to the corrugated portion of the mold.

By the way, the corrugated pipe is made of synthetic resin such as polyethylene or vinyl chloride resin, and not only the inner side surface but also the outer side surface is uneven, so that the pipe itself lacks pressure resistance,
It has a problem that it is easily damaged by external pressure.

Therefore, in order to make a synthetic resin pipe that has excellent pressure resistance and flexibility, a rigid synthetic resin reinforcement (projection) is provided on the inner peripheral surface of the pipe.
It is conceivable to attach the coil in a spiral shape. The method is such that a reinforcing ridge made of hard synthetic resin is integrally fixed along one side of one side of a flexible tape-shaped soft resin band along the lengthwise direction, and such a soft resin band is provided inside the reinforcing ridge. It is arranged so that part of it overlaps and is wound in a spiral shape, and the overlapping part is welded and integrated to rotate it.
The overlap portion is welded and integrated to form a pipe shape.

Therefore, in this method, the strip is first formed, and then transferred to the next winding step and welded, which requires time and effort for forming, and it is difficult to control the dimensional accuracy of the completed tube, and Since the pipe is formed by overlapping winding of the soft resin band, peeling of the overlapping portion becomes a problem.

(Problems to be Solved by the Invention) In view of the conventional circumstances as described above, the present invention is such that a hard ridge is already integrally formed in a spiral shape on the inner surface under the state of being extruded from an extrusion molding machine. To do so.

(Means for Solving Problems) The molding method taken by the present invention to solve the above problems is a hard synthetic resin layer on the inner side, and a soft synthetic resin layer is laminated on the outer side and extruded in a tubular shape, The hard synthetic resin layer of the inner layer hard synthetic resin layer in the extruded tubular material and the hard synthetic resin layer of the soft synthetic resin layer to be joined thereto is rotated by a shielding plate having a cutout portion at the outlet of the extrusion port to form a hard synthetic resin layer. It is characterized in that a part of the soft synthetic resin layer is discharged like a cord from the cutout portion, and the flexible tube is continuously formed by spirally welding and integrating the inner surface of the soft synthetic resin layer of the outer layer.

The laminated tubular body may include not only a resin layer but also a reinforcing material such as a braid or warp in a soft synthetic resin layer as an outer layer constituting the tubular body.

Further, the protrusions of the hard synthetic resin which are fused and integrated with the inner surface of the soft synthetic resin layer are not limited to the single spiral form, and may be the multiple spiral form. The spiral form of the protrusions is the shielding plate. It is determined by the number of notches formed in the.

Further, the molding apparatus used for carrying out the above-described molding method, on the die front end surface of the extruder for extruding and molding the tubular body in a laminated structure,
A die-shaped shield plate that closes the inner part that is slightly larger than the discharge outer diameter of the inner layer member in the die is rotatably supported in a close contact state, and a diameter smaller than the die discharge port inner diameter at the peripheral edge of the shield plate. It is characterized by forming a notch cut into a certain position and forcibly rotating the shielding plate.

The number of cutouts in the shielding plate may be one or plural, and in the case of plural cutouts, the protrusions are formed in a multi-spiral shape.

(Operation) According to the above means, the hard synthetic resin and the soft layer, which are laminated and extruded on the inner side of the soft synthetic resin of the outer layer forming the tube body, are shielded by the shielding plate having the cutout portions, and Since the portion can be discharged, the hard synthetic resin discharged from the notch is molded into a string shape, and the straight synthetic resin is rotated by the rotation of the pipe body and the shield plate, and the rigid synthetic resin string (projection)
Is attached to the inner surface of the soft synthetic resin layer in a spiral shape, and is welded and integrated with the tubular body to be continuously molded.

(Effects of the Invention) Since the method for forming a flexible tube in which the protrusion is spirally provided on the inner surface according to the present invention has the above-described configuration, it is coextruded at the stage of extrusion forming the tube. The hard resin of the inner layer is shielded and molded into a string shape (protrusion), and the tube body that goes straight on this and the shield plate that forms the string body are spirally and integrally welded to the inner surface of the outer layer. can do.

Therefore, as compared with the conventional method in which a flexible material is formed by spirally winding a tape-like material, the tubular body is extruded from the beginning to be formed into a tubular shape. There is no such thing, and stable products can be produced efficiently. Moreover, the pitch of the ridges can be easily changed and adjusted by appropriately adjusting the extrusion speed and the speed of the rotating shield plate.

Further, since the molding apparatus has a configuration in which a shield plate having a cutout portion is forcibly rotated in a close contact state on the front end surface of the die of the extrusion molding machine, it is used for molding a tubular body (hose). It can be easily manufactured by modifying the existing extruder.

Also, if there is only one notch in the shield that rotates on the front surface of the die, the protrusion will have one spiral, and if there are two, it will have two spirals, which is easy depending on the flexible tube to be obtained. Can be changed to

(Example) Hereinafter, the Example of this invention is described based on drawing.

The drawing shows a device equipped with a shield plate that forms a part of the tubular material into a string shape and welds it to the inner surface of the tubular body in an extrusion molding machine that forms a tubular body (hose) containing warp yarns. The guide sleeve (A) 2 is accurately aligned and fitted to the inside of the fixed die head 1 and fixed by the set bolt 3, and the guide sleeve (B) 4 is further provided inside the guide sleeve (A) 2.
Accurately align and fit, and set bolt 5
Between the inner peripheral surface of the fixed die head 1 and the outer peripheral surface of the guide sleeve (A) 2, and between the inner peripheral surface of the guide sleeve (A) 2 and the outer peripheral surface of the guide sleeve (B) 4. Passages 6 and 7 for guiding and flowing the molten resin for forming the tubular body are respectively defined. Further, the fixed die head 1 is provided with material supply ports 8 and 9 communicating with the above-mentioned passages 6 and 7, and a hard synthetic resin is communicated with the outer passage 7 through the material supply port 8 communicating with the inner passage 6. The soft synthetic resins are supplied to the respective material supply ports 9.

Inside the guide sleeve (B) 4, a thrust bearing 10, a bearing receiver 11, and a radial bearing 12 are mounted, and a shaft 13 is rotatably inserted inside thereof and protrudes rearward from the rear end surface of the fixed die head 1. A nut 14 is screwed into the portion, and a sprocket 15 is fixed to a protruding portion rearward of the nut 14 so that the sprocket 15 is driven and rotated by the power of a motor 16 or the like.

Further, the inner die 17 is provided at the front end of the guide sleeve (B) 4 described above.
However, an intermediate die 18 is screwed and connected to the front end of the guide sleeve (A) 2 so as to cover the inner die 17, and an outer die 19 is capped on the outer side of the intermediate die 18 and a die holder 20 is attached. It is fastened and fixed with a bolt 21 through. And the inner die 17
The outer die 19 and the outer die 19 define a passage 22 in which the resin materials of the inner and outer layers are laminated, and an introduction passage 24 for the warp yarn 23 is formed in the passage 22.

A shield plate 25 is fixed to the tip of the shaft 13 penetrating the center hole of the inner die 17 to the outside of the die by a taper pin 26, and the back surface of the shield plate 25 is flattened to the front end of the die. It is tightly bonded to the surface.

The shielding plate 25 is made disc-shaped so that its outer diameter is slightly larger than the outer diameter of the laminated surface of the inner layer resin and the outer layer resin in the passage 22, and two notches 27 and 27 'are formed on the periphery thereof. Has been formed.

The cutouts 27, 27 'are points where the inner layer resin is discharged in the form of a string to form a ridge. Since there are two cutouts 27, 27' on the circumference, two ridges are formed at the same time. As a result, a double thread is formed.

Further, the outer peripheral edge of the shielding plate 25 is formed to be tapered so that the projection can be stably formed, and the central portion thereof has an air outlet communicating with an air passage 28 formed outside the shaft 13. 29 is formed, and the tubular body extruded from the die is bulged into a circular cross section by air pressure so that the shape of the molded tubular body is maintained.

In the figure, 30 is an air feeding guide pipe, 31 is a heater,
32 is an air stop packing.

In the apparatus as described above, by supplying the hard synthetic resin a to the material supply port 8 and the soft synthetic resin b to the material supply port 9, respectively, two-layer extrusion of the hard synthetic resin inside and the soft synthetic resin outside is performed. The warp yarns 23 are inserted into the middle portion of the soft synthetic resin b on the outside thereof and extruded.

Then, the shield plate is tightly joined to the die front end surface of the extruder.
Since 25 rotates, the hard synthetic resin a of the inner layer of the tubular body to be extruded can be discharged only at the notches 27, 27 'provided in the shielding plate 25, and discharge molding is performed in a string shape, and the shielding plate is also formed. Since 25 is rotated, the above-mentioned string-shaped discharge molding is spirally attached to the inner surface of the straight tubular body. Moreover, since there are two cutouts 27, 27 'formed in the shield plate 25, the string-shaped discharge has two threads and is attached to the inner surface of the tubular body in a two-threaded shape.

Then, the ridge 34 attached to the inner surface of the tubular body 33,
The extruding of the hard synthetic resin a of the inner layer extruded in the laminated state is blocked by the shielding plate 25, and a part thereof is discharged from the notches 27, 27 'to form the ridge 34, so that the pipe body 33 is configured. Fusion integration with the soft synthetic resin b of the outer layer is very strong and stable.

Although the tubular body 33 has a single structure in the above embodiment, it is of course possible to have a two-layer or three-layer laminated structure.

Further, the spiral pitch of the protrusions 34 formed on the inner surface of the tubular body 33 can be arbitrarily changed by adjusting the extrusion molding speed of the tubular body 33 and the rotation speed of the shielding plate 25. Is.

[Brief description of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a vertical sectional front view, Fig. 2 is an enlarged cross-sectional view of an essential part, and Fig. 3 is (3)-of Fig. 2.
It is a sectional view which follows a (3) line. In the figure, 1: Fixed die head 2, 4: Guide sleeve 17,18,19: Die, 25: Shielding plate 27,27 ': Notch, 33: Tubular body 34: Protrusion

Claims (2)

[Claims] 1. A hard synthetic resin layer on the inner side, a soft synthetic resin layer on the outer side of the hard synthetic resin layer, extruded into a tubular shape, and an inner hard synthetic resin layer in the extruded tubular material and a soft synthetic resin layer joined to the hard synthetic resin layer. The hard synthetic resin side is rotated by a shield plate having a cutout at the outlet of the extrusion port, and a part of the hard synthetic resin layer and the soft synthetic resin layer is discharged from the cutout into a string shape, and the soft synthetic resin of the outer layer is discharged. A method for forming a flexible tube having a ridge formed in a spiral shape on the inner surface, wherein the flexible tube is continuously formed by spirally welding and integrating the inner surface of the layer. 2. A disk-shaped shield plate for closing an inner portion of the outer diameter of the die, which is slightly larger than the discharge outer diameter of the inner layer member, in close contact with the die front end surface of an extruder for extruding and molding a tubular body having a laminated structure. It is rotatably supported by, and a notch is cut in the peripheral edge of the shield plate to a position smaller than the inner diameter of the discharge port of the die, and the shield plate is forced to rotate freely. A flexible tube molding device with spiral projections on the inner surface.