JPS61171986A - Flexible bellows pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flexible bellows tube that is often used as a suction hose for vacuum cleaners, etc. Specifically, the present invention relates to a flexible bellows tube that is often used as a suction hose for vacuum cleaners, etc. And, in order to reduce the movement resistance of fluid such as air, the inner peripheral surface of the trough in the corrugated peripheral wall? ! - It relates to a flexible bellows tube formed into a flat plane parallel or substantially parallel to the axis.

[Conventional technology]

In the conventional flexible bellows tube of this type,
As disclosed in Japanese Patent No. 4973, the valley portion was configured in the shape of a flat plate.

[Problem that the invention seeks to solve]

However, when using the above-mentioned conventional flexible hose, the wall thickness of the trough is equal or almost equal at any part in the axial direction, and when the tube is bent, the wall thickness in the trough in the axial direction middle part of the trough is equal or almost equal. By repeating such refraction, the valley is plastically deformed into a bent state, and as a result, the inner peripheral surface of the valley can be kept flat for a long period of time. It's difficult. In addition, the tube in a softened state is extruded into a formwork whose inner circumferential surface is corrugated in the axial direction, and this extruded tube is expanded in the radial direction by blowing air. It is not possible to use the so-called blow molding method to create a corrugated bellows tube in different directions.

This is because, although the inner circumferential surface of the convex portion protruding radially inward of the formwork is formed into a flat surface, the tube portion corresponding to the formwork recess (the portion that becomes the peak of the bellows tube) expands due to expansion. When entering the formwork recess, a tensile force acts on the tube portion corresponding to the formwork convexity (that is, the part that becomes the trough of the bellows tube) toward the formwork concavity, and this tensile force causes the tube portion corresponding to the convexity to However, both ends in the axial direction are deformed so that the wall thickness becomes thinner, and as a result, the inner circumferential surface of the bellows tube valley cannot help but become a curved surface.

SUMMARY OF THE INVENTION An object of the present invention is to provide a flexible bellows tube that can maintain the inner peripheral surface of the valley flat for a long period of time and can be manufactured by blow molding.

[Means for solving problems]

The characteristic configuration of the foldable bellows tube of the present invention is that the axially intermediate portion of the valley portion is abruptly configured to protrude outward in the radial direction, and the effects thereof are as follows. be.

[Effect]

In other words, the axially intermediate portion of the valley portion is made to protrude radially outward, and the axially intermediate portion of the valley portion is thickened, so that the valley portion is not bent at the axially intermediate portion. Regardless of the bending of the tube, bending at the axially intermediate portion of the valley can be prevented. Moreover, in configuring the axially intermediate portion of the valley portion into a shape that protrudes radially outward, it is natural that the inner circumferential surface of the convex portion of the mold used for blow molding is radially As a result, during blow molding, the tube part corresponding to the convex part is crowded into the concave part, and the tube part corresponding to the concave part is crowded into the recessed part of the formwork. Since it is possible to generate a tensile force that opposes the tensile force acting on the tube portion, deformation of the tube portion corresponding to the convex portion that becomes the trough of the bellows tube can be prevented even when the tube portion is manufactured by blow molding.

〔Effect of the invention〕

Therefore, over a long period of time, the inner circumferential surface of the valley is flattened and mat-
'14・ff1KtiEaG&<#! r! - In addition, we are now able to provide a flexible bellows tube that can be manufactured using blow molding.

[Example]

As shown in Figure 1, the peripheral wall is made of synthetic resin (polyethylene, etc.) and is formed into a corrugated shape consisting of peaks (IA) and valleys (1B) spirally wound around the axis. Flexible bellows tube +
11, the inner circumferential surface (1b) of the trough (1B) in the corrugated circumferential wall is configured as a flat surface parallel to the axis;
The axially intermediate portion of the valley 5 (1B) is configured to protrude radially outward from the axially central side and gradually become thicker.

As shown in FIG. 2, the flexible bellows tube (1) has a plurality of half-cylindrical molded units (2) whose inner circumferential surface has a corrugated surface in the axial direction. Two molded bands (31, [3) connected endlessly and relatively refractably
One end of the mold (4) is rotated so as to form a cylindrical mold (4) whose inner peripheral surface has a corrugated surface along the axial direction in a predetermined path portion. A softened synthetic resin tube (6) is extruded from an extruder (5) installed on the side so as to be positioned concentrically with the mold (4), and air is introduced into the tube (6). By blowing and expanding the tube (6) in the radial direction so as to press it against the inner peripheral surface of the mold (4), the tube (6) f,
It is made by deforming it along the inner peripheral surface of the mold (4). However, as shown in FIG.
), a mold (4) for molding the molding unit (2)
), the inner circumferential surface (2a) of the spiral convex portion (2 people) is such that the central portion in the axial direction gradually has a radius such that the central portion in the axial direction of the valley portion (1B) protrudes as described above. It is configured as an arcuate surface that is recessed in a state located outward in the direction.

[Example in separate English]

By arranging a plurality of annular crests (IA) at appropriate intervals in the axial direction, the C1 peripheral wall is applied to a bellows tube formed in a corrugated shape along the axial direction.

[Brief explanation of drawings]

Figure 1 is a side view of a part of the molding device, and Figure 2 is a part of the molding device.
1 side view, No. 3 (2) is a longitudinal cross-sectional side view of the main part of the molded RF77. (1B)...Tanibe, (lb)...
Inner peripheral surface.

Claims (1)

[Claims] A flexible bellows tube in which the peripheral wall is formed in a wave shape along the axial direction, and the inner peripheral surface (1b) of the valley part (1B) in the corrugated peripheral wall is formed into a flat surface parallel or almost parallel to the axial center. In the flexible bellows tube, an axially intermediate portion of the valley portion (1B) is configured to protrude radially outward.