IL41229A

IL41229A - Apparatus for forming helical ridges on the inside surface of externally finned metal tubes

Info

Publication number: IL41229A
Application number: IL41229A
Authority: IL
Original assignee: Uop Inc
Priority date: 1972-02-07
Filing date: 1973-01-03
Publication date: 1977-01-31
Also published as: AR197801A1; AT325388B; FR2171097B1; DE2303172B2; ZA7387B; SE399188B; GB1412671A; AU5143573A; ES410790A1; JPS4889160A; CH564383A5; DE2303172C3; US3768291A; DE2303172A1; IL41229A0; JPS5211670B2; CA994089A; FR2171097A1; EG10817A; IT976884B

Abstract

Helical external fins and helical internal ridges are formed simultaneously on a tube by rolling the fins up out of the tube with inclined rotating discs, and pressing the tube onto a rotatable spirally or helically grooved portion of a multiple part internal pin. [US3768291A]

Description

Apparatus for forming helical ridgea on the inside surface of externally finned metal tube I 9353 BRIEF DESCRIPTION OP Figure X is an enlarged partly section of an Internally ribbed externally finned tube of the preeent Figure 2 is an view showing the paratus for forming the tube of Figure Figure 3 is a greatly enlarged fragmentary view showing the engagement between and oandrel Figure 4 an enlarged elevetlonal view at the dotted of Figure Figure la a view similar to Figure showing a modified Figure 6 a view similar to Figure 2 showing a different of the Figure 7 la an enlarged sectional view on line Figure BRIEF SUMMARY OF THE INVENTION It has heretofore been suggested that external helical fins and internal helical ridges may be provided simultaneously on a metal tube with external fin forming discs on a internally positioned externally helically grooves mandrel or Thus Australian patent specification describes such a method in which the interior mandrel is either fixed in position or mounted to turn with the free end of the An external finning apparatus is described in patent specification has been found that certain changes as suggested the prior art are particularly where ridgee are provided with and have a high helix angle or short and ridges be the internal support structure which haa the additional of forming the Internal helical must be fornsd of a plurality of relatively rotatable Where the discs are arranged a plurality of spaced the internal which in faet be supported for rotation on a be positioned to cooperate with a selected one or of the groups of Thus the present invention provides an apparatus for simultaneously forming external helical fins and internal helical ridges on a metal tube which comprises means for supporting a tube for axial advance including internal tube support structure having a first part provided with a smooth cylindrical exterior surface and a second part provided with a helically grooved exterior means retaining said tube support structure at a fixed rolling zone longitudinally of the tube through which the tube a pluralit of circumferentially spaced fin rolling tools at said each of said tools comprising a plurality of axially spaced groups of fin rolling means supporting said tools for rotation means supporting said first part of the tube support structure within the tube in registration with a first one of said groups of discs of said tools and supporting said second part of the tube support structure within the tube in registration with a second one of said of discs of said tools positioned to act on the tube subsequent to the action thereon of said first one group of means for effecting relative motion between said tools and tube equivalent to revolving said tools about the axis of the tube at said rolling zone and rotating said groups of discs about their own axes whereby to advance the tube through the rolling and means providing for relative rotation between said first and second parts of said tube support present invention relates to the production of an externally finned tub as seen Figure in which external fins 12 are and in which the of the tube is provided with helical ridge convolutions accordance with the present the internal extend at aubetantially eny required helix angle and nay be single or multiple start as necessary to provide the fluid flow conditions in the tube The of the internal ridge convolutions produced by the action of roll one of which ia generally at 16 in Figure three such are uniformly around the axis of the advancing plain The rolls as Illustrated separated groups 20 and 22 of the individual discs being at The of each group are of the setae are assembled in tightly abutting relation on an arbor of a lag 2 are igh t ins seed sss The 20 and ara separated by apaeera 28 and 30 and are between washers 32 and flanges arbor b nut the rolls 16 may revolve about the axis of tube while rotating on their own or tube may tate any the successively acting groups of and the group are generally of increasing diameter and the metal of the tube up into the helical 12 aa seen Figure The support structure at the Interior of the tube prises a mandrel 40 which la held against longitudinal travel and either rotate about or be restrained against The mandrel has a reduced cylindrical end portion 42 on which are rotatably received hollow pins or the flrat sleeve 44 ing a smooth exterior and the second sleeve 46 having or more helical grooves The sleeves are retained on the reduced portion of the mandrel by nut threaded to the end of the moat clearly seen in enlarged Figure the surface of the tube beneath the groups 18 of is pressed into engagement the smooth cylindrical as Indicated at The formation of by the action of the discs not only causes relative rotation between the discs and tube but also causes tive axial advance of the where the tube engages the amooth outer surface of the first sleeves in the zone dicated at 52 in Figure the tube slidea longitudinally to the right as seen In this If the tube rotating about at this then sleeve 44 will rotate on mandrel rod the mandrel itself will The action the group 18 discs to form the incipient fins without starting the mation of Internal ridges which would be shaved off due to the ation of tube between disc groups 18 and Due to sprlngback or of the clearance will exist between the surface of the tube and the sleeves 46 as indicated at the action of the aecond group 20 of discs will again press the tube contact with the adjacent which this case is the sleeve the zone of contact being seen in Figure 3 at The of the several groups 20 of discs is to further penetrate the tube material and reduce the width partially formed aa Indicated at The pressure exerted by the groups la to displace the cal groove or grooves as clearly seen at Since the tube is continuously advanced axlally by reason of the tween the Inclined discs and the helical and since the including the helically grooved sleeve la restrained against axial the tube slides axlally over the sleeve since metal displaced by the disc group 20 the helical grooves relative axial moveasnt must be companied by a relative rotation as determined by the sliding of the Incipient 62 along the helix of the groove Aa a result of the the relative sliding between the tube and cylindrical sleeve 44 will be limited to an axial the 44 rotating with the tube the relative sliding between the tube and the grooved eleeve 46 will be limited by engagement between helical grooves 48 and ridges 62 to a helical direct relative rotation la required between sleeves 44 and Xt further to be observed that due to the inner surface of the tube again moves into with respect to the cylindrical surface of sleeve as eated at this clearanoe may be increased by Increasing the diameter of sleeve and is again pressed strongly the sleeve beneath the disc group where fine 66 are finished to full tube wall thickness reduced to final as at and ridges formed to their final shape as at exact shape of grooves 48 in transverse to the as seen Figure may vary for different different helix and different desired operations with particular fluids flowing through the tube in general the grooves are relatively wide and having an obtuse included angle between the between and the of the as seen Figure 7 are composed of straight line elements interconnected at the bottoa of the groove by a snail sides 7 of the grooves 48 nay be equally inclined as seen Figure to provide the most turning force to the the side of the groove facing the direction from which the tube moves aide 72 in Figure have a greater inclination the opposite For with an included angle of the steeper angled be at an angle of while the ether side at an angle of to the tangent This provides a effective thrust tending to rotate the sleeve In Figure 4 there is enlarged elevation the ends of sleeves 44 and It will be noted that the end of sleeve 44 beveled at 76 and the adjacent end of grooved sleeve 46 is similarly beveled as seen at In Figure 5 there is shown an alternate construction in which the end of the smooth here designated 44e la flat exeept for a rounded end corner 79 which haa an extremely email radius in cross as for example about The end of the grooved here designated chamfered aa Referring now to Figure 6 there shown which the plain extends to underlie both groups 18 and while the grooved aleeve la relatively short and only the final forming disc group Since la the relative sliding between It and the tube la while that between the grooved aleeve the tube la there relative rotation between sleeves 82 and which la vlded for then on the reduced portion 86 of the It la recognised that the ube rolling operation has too effect of elongating the tube and twisting t the f n takes The uae of sepsra 46 or accommodates the twletlng or average displacement of the portions of the pressed Into engagement with the grooved with spect to the portions pressed into engagement with the anooth The forces tending to produce elongation of the tube nay be opposed by the discs and aleeve that actual elongation for the most a place only after the tube beyond the last of each group and the grooved the other the Inclination of the grooves 48 nay be gradually varied to aeeonnodate tube the lead of the groove being increased or helix angle decreased for this While the smooth sleeve 4 or 82 shown aa tatable on a aandrel be understood that where the portion therewith which will perform the function of plain sleeve 44 or and that only the grooved sleeve 46 or 84 may rot a mounted It will also be understood that plain eaves 44 or may be of slightly larger diameter to permit additional metal forming to provide cient material for the Internal The apparatus herein permits the formation of multiple start short pitch ridges of the tube For a example a grooved sleeve producing a ridge formation of six ridges has a pitch spacing between adjacent groove of and an outside diameter of The apparatus the production of ternal which extend at a greater helix angle than has hereto ore this meaning the angle measured between the axis of the tube and a line tangent to the helix curve it permits the production of tubing having multiple start By way of example ridges of satisfactory dimensions have been tubing having an internal diameter of about with a helix angle in excess of and with a pattern of ridges the apparatus production of multiple atart ridges with helix anglea excess of entirely the sleeves are formed of a hard resistant such as tungsten insufficientOCRQuality

Claims

1. ■ WHAT I CLAIM AS KT IWV8TI0N ISt 1. Apparatus for simultaneously foraing external helical fins and internal helical ridges on a metal tube which comprises means forsupporting a tube for axial advance including internal tube support structure having a first part provided with a a»ootb. cylindrical exterior eurface and a second part provided with a helically grooved exterior surface, roeana for retaining said tube support structure at a fixed rolling zone longitudinally of the tube through whioh the tube advances, a plurality of circuaferentially spaced fin rolling tools at said zone, each of said tools comprising a plurality of axially spaced groups of fin rolling dlsce, neane supporting said tools for rotation Taeana supporting said first part of the tube i i support structure within the tube in registration with a first one of said groups of dlecB of said tools and supporting said second part of the tube support structure within the tube in .registration with a second one of said group of discs of said tools positioned to act on the tube subsequent to the action thereon of said first one group of discs, aeans for effecting relative motion between said tools and tube equivalent to revolving said tools about the axis of the tube at said rolling son* and rotating said groups of discs about their own was whereby to advance the tube through the rolling zone, and means providing for relative rotation between aaid - first and second parts of said tube support struoture.

2. Apparatus as defined in claim 1 in which said internal tube support etructure comprises a mandrel, and said second part of said tube aupj>ort atructure comprises an externally grooved sleeve rotatably supported on eaid mandrel.

3. Apparatus as defined in claim 2 in which said first part of said tube support structure corapriaea a sleeve having a smooth cylindrical surface rotatably supported on said mandrel for rotation independent of said second part of said tube support atructure, . Apparatus as defined in claim 3 in which the means for retaining the tube support structure at said fixed rolling zone comprises means providing for rotation of eaid mandrel about its axis. 5. Apparatus es defined in claim 2 in which said first part of said tube support structure comprises an integral part of said mandrel, and in which the means for retaining the tube support structure at said fixed rolling zone comprises means providing for rotation of said mandrel about its axis. 6. Apparatus for simultaneously forming external helical fins and internal helical ridges on anetal tube comprising a plurality of fin forming tools positioned circuraferentially around a tube at a rolling zone, a two-part tube support member within the tube at the rolling zone, means supporting the two part tube support member at the zone for rotation relative to the tube and permitting rotation of one part relative to the other, the first part of the tube support member having a smooth cylindrical exterior surface and the second part having helical grooves in its exterior surface into which the tools press material of the tube incident to the pressure applied to the tube in the fin forming ^operation, the grooves in normal cross-section having side walls which are essentially straight throughout their major width and the included angle between the side walls of the grooves being obtuse. 7· Apparatus as defined in claim 6 in which the included angle between the side walls of said grooves la obtuse. 8. Apparatus aa defined in claim 6 in which the included angle between the eide walls of said grooves la between 90-120°. 9» Apparatus as defined in claim 7 in which the side wall of said groove facing in the direction from which the tube advances over the tube support member intersects the plane tangent to the tube support member thereat at a larger angle than does the opposite aide wall. 10. Apparatus as defined in claim 6 in which said member la provided with a plurality of separate grooves. ; 11« Apparatus aa defined in claim 6 in'which said member la provided with grooves which extend therein at a helix angle in excess of 30°» an angle measured between the tube axis and a tangent to the helix curve. 12. Apparatus ae defined in claim 6 in which, the tube support member la formed of a hard, wear-resistant material such aa tungsten carbide.