IL100049A

IL100049A - Apparatus for manufacturing corrugated tubes

Info

Publication number: IL100049A
Application number: IL1004991A
Authority: IL
Original assignee: Toyo Kagaku Kk
Priority date: 1990-11-22
Filing date: 1991-11-14
Publication date: 1996-09-12
Also published as: BE1004786A3; ES2051175A2; IL100049A0; ES2051175B1; JPH04189127A; JPH0751327B2; ES2051175R

Description

APPARATUS FOR MANUFACTURING CORRUGATED TUBES BACKGROUND OF THE INVENTION This invention relates to an apparatus for producing a corrugated tube made of synthetic resin, and more particularly to an apparatus for manufacturing a corrugated tube having a smooth inner wall surface along the length of the tube and a corrugated outer wall in longitudinal cross-section to provide enhanced flexibility and high pressure resistance.

Various types of flexible hoses or tubes made of synthetic resin and methods and apparatuses for manufacturing the same have been heretofore proposed and some of them are currently in use.

For example, United States Patent No. 4,757,400 discloses an apparatus for continuously forming a corrugated outer tube having an inner wall surface from first and second strips of synthetic resin in a softened state by the use of a plurality of rotating first and second rollers arranged in a circular array such that the rollers define an imaginary cylinder about its central axis with the axes of the rollers being parallel to one another but angled relative to the central axis of the imaginary cylinder.

Each of the first rollers is provided with a plurality of axially spaced annular ridges therearound and the ridges of the respective rollers are so arranged that the associated successive ridges of each adjacent rollers are aligned in a spiral path around the imaginary cylinder, while each of the second rollers forming extensions of the first rollers has a smooth surface. As the rollers rotate, the first strip is helically wrapped around the ridges of the first rollers and advanced axially along the imaginary cylinder with portions of adjacent turns of the first strip overlapping and joined together to form the corrugated outer tube. Onto the corrugated outer tube, the second strip is bonded and helically wrapped around the smooth surfaces of the second rollers to thereby form the inner wall surface.

However, in the prior art apparatus, the second rollers are driven by each drive shaft disposed within the imaginary cylinder at the inside of the first rollers.

Accordingly, when a corrugated tube having a small diameter is to be manufactured, the spaces for disposing the drive shafts for rotating the second rollers cannot be provided within the inside of the first rollers forming the imaginary cylinder so that with the prior art apparatus, corrugated small sized tubes cannot be manu actured.

SUMMARY OF THE INVENTION A principal object of the invention is to provide an apparatus for continuously manufacturing a corrugated tube with a smooth inner wall surface having a small diameter .

Another object of the invention is to provide an apparatus for continuously manufacturing a corrugated tube with a smooth inner wall surface from softened synthetic resin strips which enables the hot resin strips wrapped around the rollers to be cooled rapidly, thus increasing the production efficiency.

These and other objects of the invention will become apparent from the following description.

According to the invention, there is provided an apparatus for continuously manufactur ng a corrugated tube having a smooth inner wall surface along a length of the tube and axially extending spiral convolutions to form a corrugated outer wall in a longitudinal cross-section comprising : a roller assembly composed of a plurality of first rollers and second rollers each forming extensions of the first rollers along a length of each first roller, the first and second rollers being arranged in a circular array so as to define an imaginary cylinder about its central axis with longitudinal axes of the first and second rollers offset with respect to a central axis of the imaginary cylinder while the rollers are maintained in parallel one another; first feeding means for continuously feeding a first strip of synthetic resin material in a softened state transversely onto a periphery of the first rollers of said roller assembly; first drive means for rotating each of the first rollers at the same speed; each of the first rollers having a plurality of axially equally spaced annular ridges therearound, the ridges of the respective first rollers being arranged such that the associated ridges of each adjacent first roller are successively aligned one another along a spiral path; each of the second rollers having a smooth surface and an axis passing through each of the first rollers; second drive means for rotating each of the second rollers at the same speed by rotation of said axis passing through each first roller; pressure roller means having annular ridges therearound adapted to mate with recesses defined by each adjacent ridge of at least one of the first rollers, whereby the first strip is spirally wrapped around the first rollers while being axially advanced and the first strip is formed with corrugations along the ridges as it is wrapped around, to thereby form the corrugated outer wall; second feeding means disposed in an interior of the roller assembly for continuously feeding a second strip of synthetic resin material in a softened state, from an inside of the corrugated outer wall being manufactured, onto an inner surface of the corrugated outer wall so that the second strip is bonded to the inner surface of the corrugated outer wall and guided by the second rollers, whereby the second strip is spirally wrapped around the second rollers while being axially advanced together with the corrugated outer wall, to thereby form the smooth inner wall surface.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front view of an embodiment of an apparatus for continuously manufacturing a corrugated tube according to the invention with only main parts shown for simpl icity ; Fig. 2 is a schematic side view showing a driving system of rollers; Fig. 3 is a cross-sectional view showing the inside of rollers; Fig. 4 is a schematic front view showing how first and second strips of synthetic resin material are wrapped around the rollers, respectively; Fig. 5 is a partially cross-sectional schematical side view showing how the first and second resin strips are fed onto the rollers, respectively; and Fig. 6 is an enlarged partial view of the corrugated tube wall manufactured by the apparatus of the invention.

PREFERRED EMBODIMENTS OF THE INVENTION Referring to Figs. 1 to 4 , an inner smooth tube A of a corrugated tube X is formed by an imaginary cylinder 1, while a corrugated outer tube B is formed by an imaginary cylinder 2. As shown in Fig. 4, a synthetic resin strip (a) is fed from an inside die 3 onto the imaginary cylinder 1 from the inside thereof to form the inner smooth tube A. A synthetic resin strip (b) is fed from an outside die 4 transversely onto the imaginary cylinder 2 from the outside thereof to form the corrugated outer tube B. The imaginary cylinders 1> 2 are constituted by a plurality of rollers 6 with smooth surfaces and a plurality of rollers 8 with ridges 7, respectively. Each of the rollers 6 forms an extension of each roller 8.

Fig. 3 shows the details of the interior structures of the roller 6 and the roller 8. To a hollow rotatable shaft 5, the smooth surface roller 6 is fixedly secured. The rotatable shaft 5 functions as a driving shaft to rotate the smooth surface roller 6. The roller 8 with the ridge 7 is freely rotatably mounted around the shaft 5. End members 9i 9 are attached to both ends of the roller 8. The roller 6 and the roller 8 are rotatably supported between a rear support plate 10 and a front support plate 11. The rear support plate 10 is secured vertically on a mount table (not shown). A central axis 12 is passed through the support plate 10. The front support plate 11 is fixed to the end of the central axis 12. In this embodiment, eight through-openings 13 are formed with the rear support plate 10, through which each rear extension 20 of the rollers 8 is rotatably supported by means of a bearing 19. Corresponding through-openings 14 are formed with the front support plate 11. An end cover 16 is fit into the opening of the smooth surface roller 6 and a protrusion 17 of the end cover 16 is rotatably received within the through-opening 14 by means of a bearing 18.

With eight smooth rollers 6 fixedly secured to the hollow rotatable shafts 5, the imaginary cylinder 1 is formed around the central axis 12. Similarly, with eight ridged rollers 8 coaxially rotatably mounted around the shafts 5, the imaginary cylinder 2 is formed around the central axis 12. Although specifically not shown in the drawings, the longitudinal axes of the rollers 6, 8 are offset with respect to the central axis of the imaginary cylinders 1, 2, while the rollers 6, 8 are maintained in parallel one another to advance the spirally wrapped synthetic resin strips (a), (b). The ridges 7 of the rollers 8 are so arranged that the associated ridges 7 of each adjacent roller 8 are successively aligned with each other along a spiral path to advance the spirally wrapped synthetic resin strip (b).

A sproket 21 and an auxiliary sproket 25 are secured to the shaft 5 to rotate the same and in turn the roller 6, while a sproket 22 and an auxiliary sproket 30 are secured to the rear roller extension 20 to rotate the roller 8.

As shown in Fig. 2, a chain 24 is wound around the sprokets 21 and a driving sproket 23. A chain 27 is wound around the auxiliary sprokets 25 and a regulator sproket 26 so that when six sprokets 21 are driven by the driving sproket 23, all the shafts 5 are rotated at same speed with the aid of the auxiliary sprokets 25 rotated by the sprokets 21. Similarly, the rollers 8 are rotated by means of sprokets 22 driven by a driving sproket 28 via a chain 29 and all the rollers 8 are driven at the same speed with the aid of the auxiliary sprokets 30, around which a chain 32 is wound via a regulator sproket 31. The smooth surface rollers 6 are rotated faster than the ridged rollers 8 since the diameter of the inner smooth tube A is smaller than the shorter diameter of the corrugated outer tube B due to the wall thickness.

Referring back to Fig. 3, a water supply pipe 33 is disposed coaxially within the shaft 5. Cooling water is passed through the pipe 33 to the opening 34 at the front end of the pipe 33. The water is then passed through an annular space formed between the shaft 5 and the pipe 33 and into a hollow space 35 of the roller 6 to cool the roller 6, Subsequently, the water is passed into a hollow space 36 to cool the roller 8 and passed through an annular space between the shaft 5 and the pipe 33 and then to an outer reservoir (not shown) via a rotary joint 38.

A pressure roller 39 having ridges 41 is provided to mate with the ridges 7 of the roller 8 as shown in Figs. 1 and 4. The pressure roller 39 is fixed to the rear support plate 10 to be freely rotated. A plurality of support rollers 40 may be provided radially inwardly of the rollers 8 to prevent the rollers 8 from being bent inwardly.

The synthetic resin strip (b) fed substantially tangentially from the outside die 4 is spirally wrapped around the ridged rollers 8 and pressed between the rollers 8 and the pressure roller 39 to form the corrugated outer tube B as the strip (b) is partially overlapped and axially advanced due to the offset arrangement of the longitudinal axes of the rollers 8 as mentioned above. Then, the synthetic resin strip (a) fed from the inside die 3 disposed in the interior of the imaginary cylinder 1 is spirally wrapped around the smooth surface rollers 6, while simultaneously being contacted with and bonded to the inner wall of the corrugated outer tube B (see Fig. 5). The inner smooth tube A thus formed is firmly attached to the outer tube B by the pressure roller 41. While the corrugated tube X is continuously manufactured, the rollers 6, 8 are cooled by cooling water as set forth above. The details of the wall construction of the corrugated tube X are as shown in Fig. 6.

Claims

WHAT IS CLAIMED IS:

1. An apparatus for continuously manufacturing a corrugated tube having a smooth inner wall surface along a length of the tube and axially extending spiral convolutions to form a corrugated outer wall in a longitudinal cross-section comprising: a roller assembly composed of a plurality of first rollers and second rollers each forming extensions of said first rollers along a length of each first roller, said first and second rollers being arranged in a circular array so as to define an imaginary cylinder about its central axis with longitudinal axes of said first and second rollers offset with respect to a central axis of the imaginary cylinder while the rollers are maintained in parallel one another ; first feeding means for continuously feeding a first strip of synthetic resin material in a softened state transversely onto a periphery of the first rollers of said roller assembly; first drive means for rotating each of said first rollers at the same speed; each of said first rollers having a plurality of axially equally spaced annular ridges therearound, the ridges of the respective first rollers being arranged such that the associated ridges of each adjacent first roller are successively aligned one another along a spiral path; each of said second rollers having a smooth surface and an axis passing through each of said first rollers ; second drive means for rotating each of said second rollers at the same speed by rotation of said axis passing through each first roller; pressure roller means having annular ridges therearound adapted to mate with recesses defined by each adjacent ridge of at least one of said first rollers, whereby said first strip is spirally wrapped around the first rollers while being axially advanced and the first strip is formed with corrugations along said ridges as it is wrapped around, to thereby form said corrugated outer wall; second feeding means disposed in an interior of said roller assembly for continuously feeding a second strip of synthetic resin material in a softened state, from an inside of the corrugated outer wall being manufactured, onto an inner surface of said corrugated outer wall so that the second strip is bonded to the inner surface of the outer wall and guided by said second rollers, whereby said second strip is spirally wrapped around said second rollers while being axially advanced together with the corrugated outer wall, to thereby form said smooth inner wall surface.

2. The apparatus according to claim 1, wherein said second rollers are rotated independently of said first rollers .

3. The apparatus according to claim 1, wherein a diameter of said imaginary cylinder defined by recesses between respective adjacent ridges of said first rollers is slightly larger than a diameter of said imaginary cylinder defined by the second rollers.

4. The apparatus according to claim 3, wherein said second rollers are rotated faster than said first rollers such that circumferential rotating speed of the axially advancing outer wall at a bonding face to said second strip forming the inner wall is the same as that of the spirally wrapped second strip.

5. The apparatus according to claim 1, further comprising cooling means for introducing cooling medium into and passing through said axis of each second roller and returning back said cooling medium through annular spaces defined by said axis and said first and second rollers.

6. An apparatus for continuously manufacturing a corrugated tube, substantially as hereinbefore described and with reference to the accompanying drawings. FOR THE APPLICANT WOLFF BREGHAN AND GOLLER