Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3538728 A
Publication typeGrant
Publication date10 Nov 1970
Filing date15 May 1967
Priority date16 May 1966
Also published asDE1600644A1, DE1602385A1, US3435852
Publication numberUS 3538728 A, US 3538728A, US-A-3538728, US3538728 A, US3538728A
InventorsJohn Massey Tribey
Original AssigneeJohns Manville
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and apparatus for producing flexible metal ducts
US 3538728 A
Abstract  available in
Images(8)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

Nov. 10, 1970 J. M. TRIHEY 3,538,728

METHOD AND APPARATUS FOR PRODUCING FLEXIBLE METAL DUCTS Filed May 15, 1967 8 Sheets-Sheet 1 INVENTOR John Massey Tm hey ATTORNEYS Nov. 10, 1970 J. M. TRIHEY METHOD AND APPARATUS FOR PRODUCING 'FILEXIBLE METAL DUCTS 8 Sheets-Sheet 2 Filed May 15, 1967 I ATTORNEYS 1970 I J. M. TRIHEY 3.538.728

METHOD AND APPARATUS FOR PRODUCING FLEXIBLE METAL DUCTS Filed May 15, 1967 a sheets-sheet a llllllllll-lll III] III! John Massey Tn he ATTORNEYS INVENTOR J. M. TRIHEY Nov. 10, 1970 METHOD AND APPARATUS FOR PRODUCING FLEXIBLE METAL DUCTS 8 Sheets-Sheet I.

E. M o w H l lllllll Filed May 15, 1967 INVENTOR [John Massey Trlhey E f 9 'MWMZTORNEYS Nov. 10, 1970 J. M. TRIHEY 3,538,728

METHOD AND APPARATUS FOR PRODUCING FLEXIBLE METAL DUCTS Filed May 15, 1967 8 Sheets-Sheet 5 Eli- E II.

lla 7 E15- INVENTOR John Massey T": hey

TTORNEYS Nomi l0, 1970 A A J. M; TRIHEY 3,538,728]

METHOD AND APPARATUS FOR PRODUCING FLEXIBLE METAL DUCTS Filed May 15, 1967 8 Sheets-Sheet Q z i i a \NVENTOR John Massey Tr: hey

ATTORNEYS 1970 J. M. TRIHEY 3,538,728

METHOD AND APPARATUS FOR PRODUCING FLEXIBLE METAL DUCTS Filed May 15, 1967 a Sheets-Sheet v INVENTOR John Massey Tnhe v M/1M ATTORNEYS J. M. TRIHEY 3,538,728

METHOD AND APPARATUS FOR PRODUCING FLEXIBLE METAL DUCTS' Nov. 10, 1970 8 Sheets-Sheet 8 INVENTOR John Masseg Trlheg B9: w

ATTORNEYS United States Patent U.S. C]. 7223 Claims ABSTRACT OF THE DISCLOSURE A method of forming flexible corrugated tubing from strip material in which the strip is corrugated, convoluted about a mandrel and seam locking adjacent edges by means of a seam which is doubled over to form a double locked seam.

Apparatus for forming flexible corrugated tubing from strip material, having corrugated rollers to corrugate the strip, a mandrel about which the strip is convoluted by forming rollers, seaming rollers to form a locked seam between the edges of adjacent convolutions of the strip to form the tube and a spiked roller to perforate the tube as it leaves the mandrel.

CROSS REFERENCE TO RELATED APPLICATIONS The invention is useful in the manufacture of flexible ducting according to our co-pending application Ser. No. 638,392, filed May 15, 1967, entitled Flexible Ducting, now Pat. No. 3,435,852.

BACKGROUND OF THE INVENTION Field of the invention This application relates to a method for producing seam locked flexible tubing from ductile strip material such as sheet metal and provides a method of forming a strong and stable seam. It also provides apparatus for corrugating the strip, for forming it into tube, for perforating the tube and for cutting the tube into lengths.

Prior art Prior methods and apparatus for producing corrugated tubing from strip material suffer from the principal disadvantage that the strip is not strongly and permanently secured at the seams particularly where thin strip is used. The prior processes are also difficult to control due partly, I believe, to the practice of forming the corrugations in stages of progressively deepening them asthey progress through the apparatus and also to the practice of forming the tube on a power driven mandrel with freely rotating forming rollers. Furthermore I am unaware of any prior apparatus which will satisfactorily perforate corrugated tubing as it is formed.

SUMMARY The object of this invention is to provide a method and apparatus for the manufacture of flexible ducting according to our said copending application. A particular but not exclusive object is to provide an improved method and means for producing seam locked perforated tubing. A further object is to provide a method and apparatus for producing perforated tubing.

This invention provides a process for the manufacture of flexible tubing comprising forming in a strip of ductile material a series of corrugations, feeding the strip to a mandrel and causing it to convolute about the mandrel with adjacent edges of the convolutions of the strip overlapping one another and seam locking together the ad "ice jacent edges, characterised in that the adjacent edges are seam locked together by forming in one edge a deep channel and in the other edge a complementary flange, engaging the flange within the channel to form an upstanding seam, bending the seam over about its mid-point through an angle of to form a double seam and bending the double seam flat about its base. Preferably the corrugation of the strip is carried out in a plurality of stages with the number of corrugations formed in the strip increasing from stage to stage. The invention also preferably includes the further step of perforating the tube after it has been formed on the mandrel.

The invention further provides apparatus for forming corrugated tubes from ductile strip material comprising a rotatable mandrel, means to feed strip material to the mandrel, forming means located around the periphery of the mandrel to form the strip into convolutions about the mandrel with the edges of successive convolutions overlapping and seaming means also located about the periphery of the mandrel to scam lock the overlapping edges of the convolutions to form a tube.

Preferably the forming rollers are driven and serve to feed the strip around the mandrel. Preferably also the mandrel is freely rotatable.

The apparatus preferably further comprises a plurality of pairs of fluted rollers arranged to corrugate the strip as it is fed to the mandrel, said rollers being arranged to successively increase the number of corrugations formed in the strip.

The apparatus preferably further includes means to perforate the strip, said means preferably comprising a spiked roller adapted to perforate the tube as it comes off the mandrel.

Preferably there is also provided means to cut the tube into lengths, comprising a saw adapted during operation to be moved axially at the same speed as the tube.

In order that the invention will be more readily understood, a preferred embodiment of it will now be described with reference to the accompanying drawings which illustrate the method and apparatus for the construction of a light-weight flexible ducting for use in central-heating installations. In the particular construction now to be described, the tubing was produced from relatively soft aluminium strip of thickness approximately .006".

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIGS. 1 and 1a constitute a plan view of apparatus for forming tubing according to the invention, but with the coiling head removed,

FIG. 2 is a side elevation of the apparatus,

FIG. 3' is a plan view of the coiling head,

FIG. 4 is a side elevation of the coiling head,

FIG. 5 is a front elevation of the coiling head,

FIG. 6 is a sectional view on the line 66 in FIG. 2,

FIG. 7 is a sectional view on the line 77 in FIG. 2,

FIGS. 8 to 13 are enlarged diagrammatic views showing the stages of the deformation of the strip as it passes through successive pairs of rollers,

FIGS. 14 to 20 show successive stages in the formation of the lock seamed joint,

FIG. 14 is a sectional view on the line A in FIG. 5,

FIG. 15 is a sectional view on the line B in FIG. 5,

FIG. 16 is a sectional view on the line C in FIG. 5,

FIG. 17 is a sectional view on the line D in FIG. 5,

FIG. 18 is a sectional view on the line E in FIG. 5,

FIG. 19 is a sectional view on the line F in FIG. 5,

FIG. 20 is a sectional view on the line G in FIG. 5,

FIG. 21 is an enlarged plan view of part of the coiling apparatus showing the perforating means. (In this figure, for convenience and clarity of illustration, the spiking roller and the forming rollers are shown with their axes parallel to the axis of the mandrel but they are in fact disposed at an angle shown in FIGS. 3, 4 and 5.)

FIG. 22 is a sectional view showing the mounting of the perforating means,

FIG. 23 is a sectional view on the line 2323 in FIG. 22,

FIG. 24 is a plan view of the coiling head portion of the apparatus showing a pneumatic cylinder mechanism for moving the perforating means and a timing mechanism for timing the movement of the perforating means and the pipe cut-off means,

FIGS. 25 to 27 are views on the line 25-25 in FIG. 24 showing three positions of the cylinder mechanism corresponding to three positions of the perforating means; and

FIG. 28 is a cross-sectional view on the line 2828 in FIG. 24.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 and 2 of the drawings, the apparatus comprises essentially a machine frame 31 having a strip feeding portion 32, a coiling head portion 33 and a tube delivery or feeding portion 34; the tube feeding portion making an angle slightly greater than a right angle with the strip feeding portion 32. If this angle is 90 plus a, then u is the helix angle of the helical tube formed by the apparatus.

The strip feeding frame 32 carries a series of corrugating rollers 35, 35a, 36, 36a, 37, 37a, 38, 38a, 39, 39a, 41, 41a, 42, 4211. These rollers are driven by means of a suitable drive 43 from a gear box 44 and a motor 45. A coiling head portion indicated generally by the numeral 46 and shown in dotted lines in FIGS. 1 and 2 is mounted on the coiling head portion of the frame 33. This coiling head will be more fully described hereinafter. The pipe delivery portion of the frame 34 carries a driven supporting roller 47 and a number of idler rollers 48. It also carries a cutting mechanism indicated generally by the reference numeral 49.

In the construction of the tube, aluminium strip 51 of suitable width is fed through guide means 52 to the first pair of corrugating rollers 35, 35a. The roller 35 has a rib 53 which mates with a trough 54 formed between two ribs 55, 55' on the roller 35a, so that as the strip passes between the rollers, it is deformed to provide a corrugation, the dimensions of the rib and trough being such that the corrugation is curved about an inside radius of approximately .070". The strip then passes to the next pair of rollers 36, 36a. The roller 36 is provided with three ribs and the roller 36a with two mating ribs, the distance between the ribs being .300". The next pair of rollers 37, 37a is provided with two additional ribs on the roller 37a so that after leaving this pair of rollers, the strip has three corrugations. It then passes through further roller pairs (not shown) Where the number of corrugations is sequentially increased, to the rollers 38, 38a and then to rollers 39, 39a where the final number of corrugations is formed. The next set of rollers 41, 41a forms a plain edge flange 56 on one side of the strip and partly forms a deep edge corrugation 57 on the other side, the formation of this edge corrugation being completed in the final set of corrugating rollers 42, 42a. After it leaves the rollers 42, 42a, the strip passes via a coiling head guide 60 to the coiling head 46.

The coiling head 46 comprises a head frame 61 mounted on the coiling head portion 33 of the frame and carries a freely rotatable mandrel 62 around which is mounted a series of driven forming rollers 64, 65, 66 and 69 and a series of freely rotatable seaming rollers 63, 6'7 and 68. The corrugated strip is guided into the first pair of rollers 63, 64 by means of a corrugated guiding roller 71 and a guide plate 72.

In the coiling operation, the strip is fed by the guide roller 71 and the guide plate 72 to the mandrel 62 and is lapped around the mandrel by the driven rollers 64, 65, 66, 69. Due to the angular disposition of the mandrel relative to the strip, the strip is formed on the mandrel in convoluted form and the helix angle at is arranged relative to the width of the strip such that when the strip has completed one revolution of the mandrel, the plain edge flange 56 of the first convolution nests in the deep open corrugation 57 of the second convolution. With the flange and corrugation so nesting, it is passed between the forming roller 63 and the complementary anvil face 73 on the roller 64 so that the corrugation 57 is flattened to form a seam with the flange 56 and the outer half of the seam is pushed over at an angle of approximately 45. The strip proceeds about the mandrel and is guided via guide plate 74 to the next forming roller 65 whereby the bent-over portion 75 engages in a forming groove 76 to bend the portion 75 through a further angle of about 90. With the seam thus formed, it is passed to the next roller pair 66, 67 where the roller 67 completes the bending over of the portion 75 of the seam to form a locked seam 77. This locked seam is then pushed over at an angle of about 45 by the next roller 68 and is finally flattened by the groove 70 in the succeeding roller 69 to form a double locked seam.

Rotation of the tube causes the formed and seamed tube to be fed off the end of the mandrel and as it is fed off, it is guided by the rollers 47, 48. Immediately after leaving the mandrel, the tube moves past a backing roller 89 (mounted on the same shaft as the roller 65) and a spiking roller 81 located inside the tube and mounted on a cranked extension 82 of the mandrel shaft 83. The rotation of the tube as it comes off the mandrel causes rotation of the spiking roller 81 and the spikes 87 project through the troughs in the corrugations of the tube into spaces between ridges 84 on the backing roller thereby perforating the tube.

The rollers 64, 65, 66 and 69 are driven by means of universally coupled shafts 85 and drive 86 from the motor 45 and as more fully shown in FIGS. 4 and 22, the mandrel 62 is freely rotatable on the shaft 83. This shaft 83 is axially movable by means of a rack 120 mounted in a block 121 and attached to the shaft by collar 122 (see FIG. 28). The rack is adjusted by means of a pinion 123 which is rotated by a hand Wheel 124 whereby the mandrel may be withdrawn rearwardly from its position between the rollers 64, 65 etc. in the event of any mal-functioning of the coiling head. Each of the driving rollers is corrugated and has a profile to match that of the strip so that the roller firmly engages the strip. It will be observed also that the axis of rotation of each roller makes an angle on with the axis of rotation of the mandrel i.e. is angled to the mandrel at an angle equal to the helix angle of the tube. Thus the strip is at all times firmly gripped by the driving rollers and driven around the mandrel which in its turn is rotated by the movement of the strip.

As shown in FIGS. 21 to 27, the shaft 83 is a hollow shaft and carries within it further shaft which is capable of limited rotation within the shaft 83. The outer end of this shaft 90 is provided with an eccentric 91 which engages in the crank 82 which carries shaft 92 on which is mounted the spiking roller 81. The crank 82 is slidable on a mounting 93 attached to the shaft 83 so that on rotation of the shaft 90, the eccentric 91 causes the crank 82 to move inward or outward on its mounting thereby moving the spiking roller into or out of contact with the tube as it is formed.

It will be observed that the spikes 87 on the spiking roller are generally conical so that the size of hole formed by a spike varies according to the extent to which the spike penetrates. Thus as the shaft 90 is rotated to move the axis of the spiking roller towards or away from the wall of the formed tube, the diameter of the holes caused by the spikes is increased or decreased. As will be seen from FIGS. 22 to 27, the rotation of the shaft 90 is controlled by a double ended ram 135 connected by means of a crank mechanism 136 to the end of the shaft. With both ends of the ram fully extended as shown in FIG. 25, the roller 81 is fully withdrawn and no perforation is effected by the spikes. With one end extended and the other end retracted as shown in FIG. 26, the spiking roller is in a position such that the spikes penetrate to about half their effective depth and in the position shown in FIG. 27 with both ends of the ram fully retracted, the spiking roller is in its outermost position so that the spikes 87 penetrate to their fullest extent.

The operation of the rams is controlled by a timing plate 140 which is rotated through a variable speed gear box 141 by belt drive 100, which as will later be explained, also operates the cut-off mechanism. As will be seen from FIG. 1, the drive to the belt 100 is from the shaft 150 which in turn is driven by the belt 151 from gear box 44, and since the drive to the corrugating rollers, to the forming rollers and to the delivery roller 47 are all from this common gear box, all of the drives are in synchronism.

Rotation of the timing plate 140 causes cams 143, 144 and 145, arranged in the form of annuli upon the plate to operate pneumatic control valves 146, 147 and 148 respectively (see FIG. 24). These pneumatic control valves control the operation of the ram 135 and a pneumatic motor 111 which operates the cutting mechanism.

Mounted on the tube feeding frame 34 and driven by belt 100 is the cutting mechanism 49 (see FIG. 1). This cutting mechanism comprises a frame 101 on which is mounted a shaft 102 and an axially movable platform 103 which is carried on rods 104. The shaft 102 carries a cylindrical cam 105 which, as it rotates, engages a pin 112 on the underside of the platform 103 and thereby causes the platform to reciprocate on the rods 104. At its outer end, the shaft 102 carries a further cam 106 which as it rotates operates a lever 107 mounted on a shaft 108 which carries at its other end an arm 109 on which is mounted a saw 110 driven by a pneumatic motor 111. The drive to the shaft 102 is arranged such that in operation it moves the platform and therefore the saw 110 parallel to the tube as it leaves the mandrel and at the same axial speed as the tube. The rotating saw is caused, at selected and programmed intervals, by the cam 106 to move with the arm 109 into a position such that it engages the tube and severs it as it leaves the mandrel. In the actual apparatus at present in use, the platform 103 has a travel of 3" so that by appropriate programming of the cam 106, tube issuing from the mandrel can be cut into lengths of any multiple of 6". The idler rollers 48 are set at an angle and engage the corrugations of the tube as it is fed from the mandrel. The supporting roller 47 is driven at such a speed that the speed of rotation of the severed tube is slightly greater than that of the tube as it leaves the mandrel so that the severed portion of the tube is fed off along the tube delivery section of the frame at a slightly greater speed than the tube issues from the mandrel thereby separating the severed lengths from the unsevered portion of the tube.

In the formation of perforated ducts of say feet length, the cam surfaces 143, 144 and 145 on the timing plate 140 are arranged so that in every 15 feet of tube produced by the coiling head, banded patterns of large holes, small holes and no holes are produced. In a typical application, there is produced every 15 feet one plain section with no holes and four alternating sections of large holes and small holes and the cutting saw is timed to operate to cut the tube midway along the length of the plain section thereby producing a length of tubing which is plain at each end and has four alternating bands of holes, two of large holes and two of small holes, along its length.

Because the drive to the timing plate is through variable drive mechanism 141, alterations may be made to the time of operation of each of the functions controlled by the valves 146, 147 and 148. Thus by variation of the speed of the plate 140 through the gear box 141, the length of tube between saw cuts may be varied and since the spiking roller is controlled from the same timing plate the length of each band of large and small holes is varied in proportion to the variation in the length of the tube between cuts.

What is desired to secure by Letters Patent of the United States is:

1. A method for the manufacture of flexible tubing comprising forming in a strip of ductile material a series of corrugations, feeding the strip to a mandrel and causing, it to convolute about the mandrel with adjacent edges of the convolutions of the strip overlapping one another and seam locking together the adjacent edges, characterised in that the adjacent edges are seam locked together by forming in one edge a deep channel and in the other edge a complementary flange, engaging the flange within the channel to form an upstanding seam, bending the seam over about its mid-point through an angle of to form a double seam and bending the double seam fiat about its base.

2. Apparatus for forming corrugated tubes from ductile strip material comprising a mandrel, means to feed corrugated strip material to the mandrel, forming means located adjacent the periphery of the mandrel to form the strip into convolutions about the mandrel with the edges of successive convolutions overlapping, seaming means also located about the periphery of the mandrel to seam lock the overlapping edges of the convolutions to form a tube, spiking means disposed inside the tube adapted to form spiked holes in the tube, and means to move the spiking means towards or away from the tube in a predetermined pattern wherein said predetermined pattern is realted to the rate at which the tube is formed.

3. Apparatus as claimed in claim 2, and further characterized in that the spiking means is a spiking roller having spikes and there is provided a backing roller arranged on the opposite side of the tube to the spiking roller to support the tube as it is perforated by the spikes of the spiking roller.

4. Apparatus as claimed in claim 2, further characterized in that the spikes are of tapered configuration so that the size of holes caused by the spikes may be varied by varying the extent to which the spikes penetrate the strip.

5. Apparatus as claimed in claim 2 wherein troughs are formed between the corrugations of the tube and the spiked holes are substantially all in the troughs.

References Cited UNITED STATES PATENTS CHARLES W. LANHAM, Primary Examiner A. E. HAVIS, Assistant Examiner US. Cl. X.R.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1457193 *21 Feb 192229 May 1923SmithDevice for perforating oil-well casings
US1596215 *3 May 192317 Aug 1926Fed Metal Hose CorpMethod of making flexible metal tubes
US1938318 *11 Feb 19335 Dec 1933Baker & Co IncMethod of and apparatus for making pertused sheets
US2305587 *14 Mar 194122 Dec 1942Breese Corporations IncMachine for making flexible metallic tubes
US2999525 *22 Sep 195812 Sep 1961Mercer Carl ATube-perforating mechanism
US3132616 *2 Feb 196112 May 1964Bentworth Engineers N VSpiral pipe producing apparatus
US3183695 *31 Jul 196118 May 1965Republic Steel CorpApparatus and process for producing perforated, corrugated, spiral, lock-seam pipe
DE1071638B * Title not available
GB694478A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3677047 *1 Apr 197018 Jul 1972Barr David WilliamForming of tubular metal ducting
US3753363 *7 Apr 197121 Aug 1973Johns ManvilleHelically wound tubing
US3753367 *7 Apr 197121 Aug 1973Johns ManvilleHelically wound tubing
US3857159 *27 Sep 197331 Dec 1974Pacific Roller Die Co IncPipe forming method
US4058996 *17 May 197622 Nov 1977Schaeffer Claude WMachine for the manufacture of helically wound metal duct or pipe
US4353232 *28 Jan 198012 Oct 1982The Lockformer CompanyApparatus for making corrugated tubing and method for joining corrugated tubing
US4616495 *20 May 198314 Oct 1986Rib Loc Hong Kong LimitedHelically-formed pipe winding machine
US4622838 *23 Jan 198618 Nov 1986Security Lumber & Supply Co.Apparatus for manufacturing flexible corrugated tubes
US5105639 *2 Mar 199021 Apr 1992Spiro America Inc.Apparatus for forming spiral pipe
US80796195 Mar 200420 Dec 2011Bhp Billiton Petroleum Pty LimitedHose end fitting
US819661110 Aug 200712 Jun 2012Bhp Billiton Petroleum Pty Ltd.Pipe
US82258208 May 200724 Jul 2012Bhp Billiton Petroleum Pty Ltd.Hose
US835663629 Jun 200722 Jan 2013Bhp Billiton Petroleum Pty Ltd.Axially reinforced hose
US843960310 Aug 200714 May 2013Bhp Billiton Petroleum Pty Ltd.Improvements relating to hose
US870860615 Sep 200829 Apr 2014Bhp Billiton Petroleum Pty. LimitedRelating to pipe
US871379722 Oct 20126 May 2014Bhp Billiton Petroleum Pty Ltd.Hose
US872006622 Oct 201213 May 2014Bhp Billiton Petroleum Pty Ltd.Hose
US877023415 Sep 20088 Jul 2014Bhp Billiton Petroleum Pty. LimitedHose
US9188347 *16 May 201317 Nov 2015Home Energy Technologies, Inc.Remote distance transporting and integrating heat ejection connected to central heating ductwork (auxiliary heat ejectors)
US944176610 Apr 201413 Sep 2016Bhp Billiton Petroleum Pty Ltd.Reinforced hose
US20070024051 *5 Mar 20041 Feb 2007Bhp Billiton Petroleum Pty LtdHose end fitting
US20090320951 *8 May 200731 Dec 2009Joel Aron WitzHose
US20100059133 *29 Jun 200711 Mar 2010Joel Aron WitzAxially reinforced hose
US20100180976 *10 Aug 200722 Jul 2010Joel Aron WitzReinforced hose
US20100183371 *10 Aug 200722 Jul 2010Joel Aron WitzImprovements relating to hose
US20100229991 *8 May 200716 Sep 2010Joel Aron WitzHose
US20100229992 *8 May 200716 Sep 2010Joel Aron Witzhose
US20100300570 *15 Sep 20082 Dec 2010Bhp Billiton Petroleum Pty LtdHose
US20100301598 *15 Sep 20082 Dec 2010Bhp Billiton Petroleum Pty. Ltd.Hose End Fittings
US20160050948 *19 Aug 201525 Feb 2016Greg L. RobbinsCorrugated metal vent pipe and associated system and method
EP0092010A1 *15 Apr 198226 Oct 1983Marc MauryShaping of tubes having a turbulence effect for heat exchangers
EP0182001A2 *26 Jun 198528 May 1986Fritz Hahn GmbH & Co. KGMethod and apparatus for making a flexible corrugated tube, and a flexible corrugated tube made by this method
EP0182001A3 *26 Jun 19859 Sep 1987Fritz Hahn KgMethod and apparatus for making a flexible corrugated tube, and a flexible corrugated tube made by this method
Classifications
U.S. Classification72/13.6, 72/49, 72/325
International ClassificationF16L11/15, F16L59/14, B21D15/04, B21C37/12, F16L11/16, F16L59/153
Cooperative ClassificationB21C37/124, B21C37/12, F16L11/15, F16L11/16, B21C37/157, B21D15/04
European ClassificationB21C37/15G2, B21C37/12E, B21C37/12, F16L11/15, B21D15/04, F16L11/16