JPH0450896B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bellows tube made of synthetic resin, and particularly to a bellows tube with an inner tube that is integrally provided with a smooth inner peripheral surface.

(Prior art) Synthetic resin bellows pipes are highly flexible as they can be easily bent by deforming the peaks and valleys, and the peaks and valleys function as annular ribs, making them flexible in the radial direction. It has an excellent property of being difficult to deform, and is widely used for various purposes. However, because its inner circumferential surface is bellows-shaped, there is a problem that there is a large flow resistance when passing fluid. If the pipe contains solid content, there is a risk that this solid content will accumulate and remain in the troughs, and if pressure is applied inside the pipe, the peaks and troughs may deform and easily extend.

Therefore, a bellows tube with an inner tube has been proposed in which a cylindrical inner tube is integrally formed on the inner periphery of the bellows tube.One of the methods for manufacturing the bellows tube is to create a bellows tube in a tunnel-like movable molding space having a bellows-shaped inner circumferential surface. In the method for producing a bellows tube, in which a bellows tube is formed by supplying an uncured synthetic resin cylindrical body and pressing it against the inner circumferential surface of a movable molding space by applying internal pressure, a There is a method in which an uncured synthetic resin cylindrical body is supplied and an appropriate internal pressure is applied to form an inner cylinder in contact with the inner periphery of the bellows tube.

(Problem to be Solved by the Invention) However, in this method, the synthetic resin cylindrical body that becomes the bellows tube is quickly cooled and hardened and stabilized because its outer peripheral surface is in contact with the mold that forms the movable molding space. Since the synthetic resin cylindrical body that serves as the inner cylinder is only in contact with pressure fluid such as compressed gas on both the inner and outer circumferential surfaces, cooling and curing is slow and the curing time is unstable.
In order to maintain the pressure inside the inner cylinder, the inner cylinder may come into contact with the uncured stopper, which is fitted inside the cylinder, and the inner cylinder may be torn, or a smooth inner cylinder may not be formed, resulting in stable production. was difficult.

In view of these conventional problems, an object of the present invention is to provide a method for stably manufacturing a bellows tube with an inner cylinder using a method for manufacturing a bellows tube similar to that described above.

(Means for Solving the Problems) For this reason, the present invention forms a tunnel-like movable molding space having a bellows-shaped inner peripheral surface with an upper mold and a lower mold consisting of a large number of divided molds that circulate. By supplying an uncured cylindrical body made of synthetic resin into the movable molding space and applying fluid pressure therein, the cylindrical body is pressed against the inner peripheral surface of the movable molding space and formed into a bellows shape. In a method for manufacturing a bellows tube similar to that described above, a pre-formed synthetic resin cylinder is supplied inside the uncured cylinder in a radially folded and contracted state, and a fluid pressure is applied from the tip of the cylinder. A method for producing a bellows pipe with an inner cylinder made of synthetic resin, in which the outer circumferential surface of the bellows-shaped cylindrical body is pressed into contact with the inner periphery of the cylindrical body, and the outer circumferential surface of the cylindrical body is integrated with the inner periphery of the bellows-shaped cylindrical body. This is what we provide.

(Function) According to this method, the cylindrical body that becomes the inner cylinder is pre-formed, and if it is expanded from the folded and contracted state, it will become a completely smooth cylindrical shape, so this cylindrical body is used. As a result, a bellows tube with an inner cylinder can be manufactured stably in the same way as a normal bellows tube is manufactured.

(Example) Next, an example of the present invention will be described based on the drawings. 2 to 4 show a bellows tube 1 with an inner tube to be manufactured, in which a cylindrical inner tube 3 is attached to the inner periphery of the bellows tube 2, which has a corrugated cross-sectional shape in the axial direction, that is, the inner periphery of the trough. are integrated.

The manufacturing apparatus for the bellows tube 1 with an inner cylinder will be explained with reference to FIGS. 1, 5, and 6. 5a, 5b
1 is an upper mold and a lower mold constructed by connecting a large number of split molds 4 in an endless manner so as to circulate and move, and the upper mold 5a and the lower mold 5b have a bellows-like shape in a part of their circulation path. A tunnel-shaped movable molding space 6 having an inner peripheral surface 6a is formed. Reference numeral 7 denotes a nozzle of the extruder main body, which is disposed so as to concentrically supply an uncured synthetic resin cylindrical body 8 to one end of the movable molding space 6 from its tip. A through hole 9 is bored at the axial center position of the nozzle 7, so that a preformed synthetic resin cylinder 10 can be supplied to the inside of the cylinder 8 through the through hole 9. It is configured. Since the diameter of the through hole 9 is smaller than the diameter of the cylindrical body 10, the cylindrical body 10 is inserted into the through hole 9 in a radially folded and contracted state. Further, a passage 11 for supplying a pressure fluid such as compressed air into the inside of the cylindrical body 8 is bored in the nozzle 7 around the through hole 9, and a connection base for a pressure fluid 15a is provided at the outer end of the passage 11. 12 is installed. Note that this passage 11 can also be used as the through hole 9. On the other hand, a stopper 13 is fitted to the tip of the cylinder 10 to seal it, and a pressure fluid 15 is passed through a connection pipe 14 provided on the stopper 13.
b is force-fed into the cylinder 10, and the cylinder 10, which has been contracted in the radial direction, is expanded in the movable molding space. Note that the pressure of the pressure fluid 15b is set higher than that of the pressure fluid 15a.

In the nozzle 7, 16 is a hollow nozzle body, which is bent in an L-shape and gradually tapers in diameter toward the tip.
a is attached to the extruder main body 17. 18 is a screw of the extruder main body 17. A core 19 is arranged inside the nozzle body 16, and the nozzle body 16
A synthetic resin passage 20 whose cross-sectional area and diameter gradually decrease is formed between the inner surface and the outer surface of the core 19, and the cylindrical body 8 is formed of the synthetic resin that passes through this passage.
A support block portion 21 is formed at the base of the core 19, and this support block portion 21 is connected to the nozzle body 1.
It is tightly fitted and held in the hollow part of the bent part of No.6. 22
is a resin passage hole bored in this support block portion 21.

In the above configuration, the upper mold 5a and the lower mold 5b are circulated to form the movable molding space 6, and
The cylindrical body 10 is inserted into this movable molding space 6, its tip is sealed with a stopper 13, pressure fluid 15b is supplied, and the extruder main body 17 is operated to extrude and mold the cylindrical body 8, and the pressurized fluid 15a is If you supply
The cylindrical body 8 is pushed radially outward by the pressure fluid 15a and pressed against the bellows-shaped inner peripheral surface of the movable molding space 6 to form a bellows shape, and the cylindrical body 10 is pushed radially outward by the pressure fluid 15b. It expands and is pressed against the inner periphery of the bellows-shaped cylindrical body 8 before being cooled and hardened, and is integrated into the inner cylinder 3. In this state, the cylindrical body 8 is cooled and hardened to become the bellows tube 2. In this way, the bellows tube 1 with an inner tube is formed in which the inner tube 3 is integrated with the inner periphery of the bellows tube 2.

When the bellows tube 1 with an inner tube reaches a predetermined length, the bellows tube 1 with an inner tube is compressed or bent to seal it near the exit of the movable forming space 6, and then its tip side is cut, and the cut end is immediately cut off. Continuous molding is possible by fitting the stopper 13 into the portion.

Further, the cylinder body 10 is flexible enough to be folded and contracted in the radial direction, but the bellows tube with an inner cylinder 1
When the inner cylinder is in this state, it is integrally connected to the trough of the bellows tube 2 with a small pitch, so it has sufficient strength necessary for the inner surface of the tube body. Furthermore, bellows pipe 2
If there is a possibility that the integration of the inner cylinder 3 and the inner cylinder 3 is insufficient, supply adhesive together with the pressure fluid 15a,
The cylindrical body 10 may be supplied with an adhesive applied to its outer surface.

(Effects of the Invention) According to the method of manufacturing a bellows tube with a synthetic resin inner cylinder of the invention, as is clear from the above description,
The molded synthetic resin cylindrical body is folded in the radial direction and contracted, and then fed into the uncured cylindrical body that is forming the bellows tube, and fluid pressure is applied inside the cylindrical body from the tip of the cylindrical body. The outer circumferential surface of the cylindrical body is pressed against the inner circumferential surface of the cylindrical body before it is cooled and hardened, and is integrated with the inner circumferential surface of the cylindrical body. The bellows tube with an inner tube can be easily manufactured by using the conventional manufacturing technology for bellows tubes without requiring complicated extrusion molding means for the inner tube.

Furthermore, since the cylindrical body that becomes the inner cylinder can be formed in advance to have a constant diameter and a constant thickness, when the cylindrical body is expanded from a folded and contracted state, the fluid pressure supplied into the cylinder may vary slightly. The thickness of the cylinder does not change even if it occurs. Therefore, a cylinder having a constant thickness over the entire length can be integrated with the inner circumferential surface of the bellows tube, and the inner circumferential surface of the cylinder can be undulated. It is possible to obtain a highly accurate bellows tube that can be formed on a flat surface without causing any damage.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an enlarged cross-sectional view of the main parts of the manufacturing process, FIG. 2 is a front view of a bellows tube with an inner cylinder, and FIG. 3 is a cross section taken along line A-A in FIG. 2. 4 is a sectional view taken along the line BB in FIG. 3, FIG. 5 is a schematic diagram of the manufacturing apparatus, and FIG. 6 is a partial sectional view of the nozzle. 1... Bellows tube with inner tube, 2... Bellows tube, 3...
Inner cylinder, 4... Divided mold, 5a... Upper mold, 5b... Lower mold, 6... Moving molding space, 6a... Bellows-shaped inner peripheral surface, 7... Nozzle of extruder main body, 8... Not yet Hardened cylindrical body, 10...cylindrical body, 15a, 15b...pressure fluid.

Claims (1)

[Claims] 1. A tunnel-shaped movable molding space with a bellows-shaped inner peripheral surface is formed by an upper mold and a lower mold consisting of a large number of divided molds that circulate and move, and an uncured cylindrical body made of synthetic resin is placed in this movable molding space. The cylindrical body is pressed against the inner circumferential surface of the movable molding space and formed into a bellows shape by supplying and applying fluid pressure to the inside of the cylindrical body, and is preformed inside the uncured cylindrical body. The cylindrical body made of synthetic resin is supplied in a radially folded and contracted state, and fluid pressure is applied to the inside from the tip of the cylindrical body to expand the cylindrical body, thereby producing the bellows-shaped cylindrical body. A method for manufacturing a bellows tube with an inner cylinder made of synthetic resin, characterized in that the outer peripheral surface of the cylindrical body is brought into pressure contact with the inner periphery of the cylindrical body to integrate the cylindrical body before cooling and hardening.