DE2303192A1 - FIBER TUBE AND THE METHOD AND DEVICE FOR ITS PRODUCTION - Google Patents

Description

DR-INQ. DIPU.-INQ. M. SC. DIPL. PHY3. 3H. DIPL.-PHYS.

«HÖGER - LEGAL RIGHT-GRIESSBACH - HAECKER

PATENT LAWYERS IN STUTTGART

A 39 923 b
January 19, 1973
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universal Oil Products Company Des Plaines, Illinois, U.S.A. Ten UOP Plaza - Algonquin & Mt Prospect Roads

Finned tube and method and device for its manufacture

The invention is concerned with a finned tube, in particular made of difficult-to-machine metallic material and with a method for producing such a finned tube and with a device for carrying out this method.

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Rolling up material from the outside wall of a pipe using multiple sets of axially aligned rolling disks rotation of the same has been known for a long time. When working with malleable materials such as copper and particularly when high ribs are not required, the present methods are satisfactory. But when Difficult-to-machine metals or alloys are to be processed, especially if the material is hardened occurs, as it does with stainless steel, however, it has not heretofore been possible to achieve the desired results. The problems have become particularly difficult when making ribs with substantial wall thickness throughout should be, i.e. ribs with a relatively thick outer edge compared to the ribs, where the outer edge or the Rana is thin in the shape of a knife.

The invention was therefore based on the task of proposing a finned tube made of difficult-to-process metallic materials, in which the ribs are relatively high and have a comparatively large width at their edge. Further the invention was based on the object of a method for production to propose such finned tubes and a device for performing this method.

The object is achieved by a finned tube, in particular made of a metal material that is difficult to machine, which thereby is characterized in that the ribs are relatively high and have a relatively large width at their tip.

There is an ancestor for the production of such a finned tube particularly proven, which is characterized by

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that initially in a first rolling step ribs are considerable be rolled at a lower height, that the tube is then annealed and that a second rolling step is then carried out, to increase the height of the ribs.

A device which is characterized in that it comprises several arrays of axially aligned washers that are used one after the other to produce ribs on one single tube are used that the rolling disks have radially outwardly converging side parts that the Disks have a rounded cross-section at their edge or circumference and that the profiles of corresponding disks are essentially identical in the arrangements. The inventive Finned tubes are particularly suitable for the passage of liquid sodium, which is cooled by air will. They are therefore especially suitable for the cooling circuits of nuclear reactors, in particular of so-called fast ones Breeders.

A finned tube according to the invention is preferably produced in two or more rolling steps, the tube is annealed between the individual rolling steps. The successive Rolling steps are essentially similar, except for successive rolling steps the first disks of the rolling device operate in the spiral grooves left behind from a previous rolling step are. In each rolling step, at least one set of several coaxially arranged disks is used, which are touch each other and are in contact with the tube, the axis of the set of disks and the axes of the Sets of washers making an angle with the pipe axis

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or include in order to create a to generate spiral rib arrangement. The first few slices of each set have a rounded edge called the one has relatively short radius of curvature to facilitate penetration into the material of the pipe and successive ■ Discs increase in diameter by relatively large amounts. As a result, one or more relatively deep and relatively narrow spiral grooves are quickly produced, and there are during a first rolling step, relatively large amounts of metal to form a relatively wide and relatively low spiral rib rolled up, while in one or more subsequent rolling steps considerable amounts of metal into the base or Foot parts of the previously formed and shaped ribs are rolled up. The rolling disks following the first rolling disks In the sets of rolling disks are designed so that they have an increasingly, wider edge and a relatively have a slight increase in diameter from disk to disk, in order in this way a gradual widening and To create deepening of the spiral groove and to displace even more metal in the area of the rib. In addition, the angle which the sides of the disks enclose with each other increasingly larger, so that the ribs at their tip acquire a thickness, which reaches a very significant percentage of the base thickness of the rib. The subsequent rolling step (s) are made with sets of disks that have an increased thickness or pitch compared to the pitch of the disks of the set of disks used immediately before, so that the helical structures on the tube form a get bigger slope.

Further details and advantages of the invention are provided below explained in more detail using a drawing. In the drawing show:

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January 19, 1973 ^{Z ö UJ} '

Fig. 1 is a partial cross-section through the wall of a finned tube according to the invention,

2 shows the generalized outline of an individual rib of a ribbed tube according to the invention,

3 shows a part similar to that of FIG the same finned tube after the first rolling step and with partially finished fins,

4 shows an enlarged schematic representation in which the cross-sections according to FIGS. 1 and 3 are superimposed are laid

Fig. 5 is a schematic representation of part of the rolling disks of a set of rolling disks for a device for producing a finned tube according to the invention and

6 shows an enlarged detailed illustration of a roller disk of a device for producing a finned tube according to the invention.

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If one first looks at FIG. 1, it can be seen that in this an enlarged cross-section through a portion of a finished one Finned tube Io is shown according to the invention. The finned tube has pretty much the following critical dimensions :

Dimension Reference number Size in mm (approx.)

Rib height 12th 3.3 Rib thickness on the
top 14th o, 69 Rib thickness on the foot 16 I, o4 Average rib thickness 18th o, 86 Distance between ribs on average 2o 1.47 Wall thickness 22nd 2.72

It is clear from the table above that with an extraordinary rib height of 3.3 mm, the rib thickness at the top is over 20 % of the rib height and also over 65 ^! the thickness of the ribs at the base of the rib.

A more generalized rib cross-section of a single one Rib or the outline of such a cross-section is shown in

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Fig. 2 shown in which the individual dimensions are entered to to clarify the rib thickness at the top and at the base as well as the rib height and the wall thickness.

From the foregoing description it is clear that the fins of the finned tubes according to the present invention are different from the usual ones Ribs differ by their unusual thickness at the top of the rib and by their height compared to their mean thickness. It can generally be stated that the ribs of the finned tubes according to the invention have a minimum height of about 2.54 mm, have a thickness at their tip which is not less than 20% of the rib height at their base or their foot have a thickness that is not less than 25% of the rib height and have a thickness at the tip, which is not less than 60% of the thickness at the base. These values lead to a rib cross-section, which by a considerable Rib thickness is characterized at the top and which further proves to be advantageous as the whole Fin surface is useful for heat transfer, wherein at the same time a considerable gain in surface area is achieved.

During the manufacture of the new finned tube, as mentioned, a number of successive rolling processes are carried out, an annealing process taking place between successive rolling processes. In Fig. 3, the cross-sectional shape is partial Shaped ribs shown after a first rolling process, namely for a method which with two rolling steps

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th works, of which a finned tube according to FIG. 1 is made with the aid of the second. In Fig. 3 has the partially completed Finned tube 26 approximately the following dimensions:

Dimension. Reference number size in mm (approx.)

Rib height 2 8 2.16

Rib thickness on the

Peak 3o o, 81

Rib thickness at the foot 32 ο, 99

Rib thickness on average 34 o, 89

Rib spacing im

Medium 36 1.37

Wall thickness 38 3.28

From the table above it can be seen that the average Rib thickness is approximately Uo% of the rib height and that the thickness at the top of the rib is over 80% of the thickness the base of the ribs.

In Fig. 4, the outlines of the cross-sections of the finished finned tube and the semi-finished finned tube are drawn next to one another. The pipe inner diameter or the inner wall 4o of the pipe was used as a common reference line, and the partially finished rib 42 at the left end of the Tigux ¹ was, as far as the lateral position is concerned, over the finished rib

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44 laid. From the comparison of the cross-sectional outlines it becomes clear that the groove or the channel between the ribs is enlarged by the amount shown at 46 during the second rolling step was, while the end or the tip of the rib around the at 48 The amount shown has been shifted radially outward. At the same time it is noted that the outline of the entire upper part of the partially finished rib corresponds almost exactly to the central part of the finished rib, as indicated by the Correspondence of the outlines or side surfaces at 5o clearly will.

Fig. 4 also shows graphically a very important feature of the present invention, which is that in which the second rolling step following the first rolling step increases the pitch or the axial distance between adjacent ones Costal ducts enter. In the exemplary embodiment considered on the basis of FIGS. 1, 3 and 4, the slope was or the axial distance between the rolling disks, which were used to manufacture the semi-finished finned tube according to FIG. 3, about 2.08 mm, while the pitch or the distance of the rolling disks used for the completion of the finned tube according to FIG. 1 2.18 mm. This corresponds to an increase in the incline or the aisle by approximately 5%. However, this continues presupposes that with multiple pass rolling the slope generated in the first rolling step is sufficiently smaller than that desired for the end product Incline, which depends on the required number of ribs per cm (in the present case, each are about 2.54 cm

11 ribs provided).

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Figures 5 and 6 show an enlarged schematic representation one side of an arrangement or a set 5 4 of rolling disks, which are designated by the reference numerals 56a to 56q are. An essential feature of the device Z; Ur implementation of the method according to the invention is that the profiles or the cross-sectional shapes of the side surfaces of the outer portion of corresponding rolling disks in two or more sets or arrangements are substantially the same. "The the only significant difference between corresponding disks is the thickness of the same, which is shown in FIG 5 8 is drawn and which, as explained above, when using different sets of rolling disks is increased in successive rolling steps.

In Fig. 6, the cross-sectional outline is the generalized Shown shape of the outer part of a rib roll disc. In this figure the side surfaces are the outer part of the rolling disk denoted by 6o and extend essentially in a straight line in the radial cross section through the rolling disk. the In other words, side surfaces running in a straight line in cross section define a truncated cone, its opening angle is determined by the angle A between the cross-sectional straight side surfaces 6o and the line 62, which is parallel runs to the radial center plane 64 of the rolling disk. If the side surface 6o is inclined by 5 ° with respect to the plane 64 (or the line 6 2 intersects at this angle), then the opening angle of the cone is 17o.

The rolling disk according to FIG. 6 is rounded at its circumference 65,

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and its radius of curvature is denoted by R in this figure. The straight side surfaces 6o go smoothly over areas 66 into the edge area curved according to the radius R. It goes without saying that the rolling disc is all the easier in the Material of the pipe penetrates the smaller the radius R is.

The thickness of the rolling disc adjacent to the rounded peripheral area 65, 66 is denoted by 68. This dimension is determined by the distance between the intersection points of the tangent 67 determined to the tip 65 with the extensions of the straight side surfaces 6o. The thickness of each slice in the area the cylindrical hubs, which are at a fixed distance 69 from the circumference of the rolling disks, are denoted by 7o.

The continuous change in the shapes and dimensions of the rolling disks 56a to 56q naturally determines the special type in which the metal of the tube is displaced and brought into its final shape.

First of all, it is necessary to achieve rapid penetration into the pipe, in order to achieve a relatively narrow but proportionate one to produce a deep groove, between the adjacent turns of which a relatively wide and short rib results, whose metal material eventually becomes the outer tip of the rib. Due to the special shape and the increase in dimensions successive discs, the groove or the channel gradually becomes deepened and widened by determining the diameter, the tip width and the radius of curvature of the edge of the

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Discs can gradually increase in order to press more metal into the area of the ribs, this metal possibly the forms the middle part of the finished ribs and at the same time a lateral pressure is exerted in order to give the material the desired To give shape. In general it can be said that some of the first disks, for example the first six disks 56a to 56f, have a thickness 68 at the tip which is constant and about 75% of the thickness 68cer tips of some of the latter Makes disks, for example the last five disks 5 6m to 5 6q, with the thickness of the middle rolling disks at the Peak gradually increases.

At the same time as the thickness 68 increases at the tip, the radius R increases at the rounded circumference 65. The radius R is included in the first slices advantageously about half as large as the radius R of the last slices, the The radius R of the rolling disks in the central area of the device gradually increases from disk to disk.

The thickness 7o of the foot or the base which in a constant Distance 69 from the circumference is measured for some of the first rolling disks, for example for the six rolling disks 56a to 56f, constant and gradually decreases with the further rolling disks, up to some of the last disks, for example the last five rolling disks 56m to 56q, which have a uniform base width that is about 80% of that of the first rolling disks 56a to 56f.

It is understood that the increase in width 6 8 at the

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Tip with a simultaneous reduction in the base width 7o leads to a reduction in the angle A, which leads to the inclination corresponds to the conically tapering side surfaces 6o with respect to the radial center plane 64. When making the The finned tube considered here, for example, the angle A from about 5 for some of the first rolling disks to about 1 decreased in the last rolling disks, this decrease occurring gradually in the middle rolling disks 56f to 56m.

Some of the first disks are designed so that a fast Penetration into the pipe wall takes place, which is why the disk diameter in these first rolling disks is compared increased very considerably to increase the diameter of the subsequent disks. In addition, the sentences of Rolling disks / arranged with respect to the pipe so that the first disk 56a is already to a considerable depth, for example penetrates about 0.76 to about 1.02 mm into the metal of the pipe .

Some of the next disks, for example the two disks 56b and 56c, have a diameter equal to the diameter the previous disc by about 0.25 to 0.51 mm. In the case of the other rolling disks, the increase in diameter is then a little less and is, for example, about a third of the increase in the first rolling disks. Further For some of the last disks of the rolling disk assembly, the diameter of one disk may be compared to that of an adjacent disk be identical, thereby reducing the average change in dimensions even further.

■ f "■» Ί ti

in the arrangement for the first rolling step

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ORIGINAL INSPECTED

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The penetration of the edges or the circumference of the disks into the material of the tube and that of the rolling disks onto the tube The pressure exerted has the effect that ribs are formed, that the inner diameter of the pipe is reduced, that the effective Wall thickness between the fin turns is reduced and that the tube is stretched. To compensate for the extension of the Tube, which accompanies each rolling step, is the axial distance between the median planes of the disks, which is for each set of rolls is even, in successive sets ^ i.e. increased in arrangements used one after the other.

It is common to use three sets of rolling disks evenly spaced around the pipe. on in this way the radial force components acting between the rolling disks and the tube are balanced. Furthermore but also a pin or mandrel is provided to to obtain a predetermined inner diameter in the finished finned tube. The mandrel is cylindrical and its diameter is a few thousandths smaller than the inside diameter of the Pipe before it gets between the sets of rolling disks. _, The first rolling disks, which are narrower on their circumference and in which the rounding on the circumference has a smaller diameter has than in the following roll disks, penetrate into the material of the pipe without its inside in Bringing contact with the thorn. Somewhere in the middle of the set of rolling disks, however, the radial pressure is sufficient to to press the inner surface of the tube against the mandrel. The further increase in the effective diameter in the following

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Discs and the widening of the tip of the same then causes a higher displacement of metal than is the case, if at the same time the inner diameter of the pipe is reduced.

It has already been mentioned that the profiles of the edges or peripheral parts corresponding disks in successively effective sets of rolling disks essentially the are the same as in the previous sentences and differ from these only in thickness. It is wrong that all of the rolling disks have flat sides and are arranged to lie side by side with one another and one another prop up.

When carrying out the method for producing inventive Finned tubes, the front end of the tube to be machined is slightly tapered in order to gently engage the first Slices of the sets of rolling disks used for the first rolling step is carried out to achieve and the sets of rolling disks are arranged at such radial intervals that the first rolling disk after passing the tapered end piece penetrates deeper into the pipe material, for example by twice the amount by which the recess penetrates some of the next roll disks is enlarged. In the subsequent rolling steps, polygons are to be performed after annealing the sets of rolling disks are arranged so that the first rolling disk is at the bottom of the groove or channel of the partially completed Finned tubesc rests without significant penetration would take place.

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The way in which the annealing process is carried out naturally depends on the material used. However, when the pipe, for example made of stainless steel of type 3ο ¹ *, the tube is at a rate of about 15.2 cm / see pushed through an annealing furnace with a muffle length of about 4 m length _S 56, in which a furnace Temperature of about Io66 C is maintained. The tube initially had a hardness of R * 77 (ie after the first rolling step) and after annealing its hardness was reduced to R.72.

In general it can be said that the opening angle of the between the cone lying on the sides of the rolling disks increases from a value of about 165 to 170 degrees to about 178 in each set.

When looking at Fig, U it can be seen that when the rib height is increased in the second rolling step, the increase U2 in the outer diameter of the Rxppen is approximately equal to the increase in the depth between the ribs or equal to the reduction% 6 in the wall thickness of the pipe.

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Claims (1)

A 39 923 h
19th January 1973 Patent claims: Iy finned tube, especially made of difficult-to-machine metallic Material ^ characterized by that the ribs are relatively high and have a relatively large width at their tip. 2. finned tube according to claim 1, characterized in that it is made of stainless steel that there are 10 to 12 ribs or rib turns per approximately 2.54 cm that the rib height is at least about 2.54 mm, that the rib thickness in the area of the tip of the rib is about 15 to 25% of the rib height and that the rib thickness near the base of the rib is about 25 to 35% of the rib height. 3. finned tube according to claim 1 and 2, characterized in that the fin height is at least about 2.92 mm. 4. The method for producing a finned tube according to claim 1 to 3, characterized in that initially in one first rolling step ribs are rolled considerably less height that the tube is then annealed and that then a second rolling step is performed to increase the height of the ribs. 5. The method according to claim 4, characterized in that the pipe is carried by a mandrel in the rolling zone and that during this rolling step, a radially inwardly directed pressure is exerted on the pipe, which over the Circumference of the pipe during the last processing stages 309832/0898 A 39 923 h
X January 9, 1973 k-35 is increased considerably with each rolling step in order to obtain the desired wall thickness. 6. The method according to claim 4 and 5, characterized in that in each rolling step before and after the annealing initially relatively deep and narrow grooves are produced, whereby relatively wide ribs are formed, which are partially formed from the material that was formed by the formation of the grooves was displaced from the tube, and that then further material is pressed into the area of the ribs by gradually widening and deepening the grooves, with pressure being exerted on the sides of the ribs at the same time in order to achieve a relatively large height in the course of the two rolling steps to achieve the ribs with a relatively large width of the ribs at their tip. 7. The method according to claim 4 to 6, characterized in that that with successive rolling steps the slope of the ribs or rib windings is increased. 8. The method according to claim 4 to 7, characterized in that that multiple sets of coaxial scrolls are used at each scrolling step, the scrolling disks each Set include a few first rolling disks, which have a predetermined small radius of curvature on their circumference have and whose diameter increases from rolling disk to rolling disk by a considerable predetermined amount, so that the rolling disks in the material of the pipe quickly and penetrate to a considerable depth, / that the rest Roll disks of each set have an increasingly larger radius of curvature on their circumference as they increase 309832/0896 A 39 923 h 19. Jaimar "73
k-35 JB the diameter from rolling disk to Holl disk is considerable, is less, so that in each rolling step a relatively thick rib is initially rolled out of the material of the tube becomes »which is then shaped into a higher rib. Method according to one or more of claims 4 to 8, characterized in that ribs are produced whose thickness at the tip is at least half the thickness the basis is that pressure is repeatedly exerted on adjacent narrow zones in a first rolling step, and progress a. along a helical path which leads around the pipe to get into the material -.es pipe penetrate and initially a considerable amount of metal to press into a coiled, short, thick 7, so that material is gradually displaced from wider zones, whereby the increase in the depth of penetration is reduced while a lateral pressure is exerted on the rib after that the exertion of pressure is stopped and the tube is annealed, that then, in a second rolling step, pressure is repeated in the coiled space between the fin windings is exercised, in narrow zones with increased penetration into the pipe material, to a further to press a considerable amount of material into the rib, and that finally material is displaced by creating zones, greater width penetrates the pipe material with reduced penetration speed while a lateral pressure is exerted to bring the rib into the desired final shape. 309832/0896 A 39 923 b 10. The method according to claim 9, characterized in that pressure is exerted at the beginning of each rib forming process, in order to penetrate the pipe material while displacing metal to achieve, which is several times as great as the penetration, which is when the subsequent use of Pressure is reached. 11. The method according to claim 10, characterized in that during the first rolling step a rib with a minimum height of approx. 1.52 mm is created and during the second rolling step a minimum height of the rib of approx 2.54 mm is reached. 12. The method according to claim 11, characterized in that a rib with a minimum height during the first rolling process of about 1.9 mm is generated and that a rib with a minimum height of about 2.92 mm is produced. 13. The method according to one or more of the preceding claims 4 to 12, characterized in that first a smooth tube is advanced over a first mandrel that fins are formed by a first assembly is pressed into one side of the advancing tube by axially aligned rolling disks, the axis of the assembly is inclined at a small angle with respect to the axis of the tube and with a relative rotation between the arrangement and the pipe takes place in order to produce tilt turns on the outside of the pipe in this way, that the first rolling step is then ended, that the tube is annealed and that then a second rolling step with a swide arrangement of rolling disks is carried out to 309832/0 896 A 39 923 h
January 19, 1973 obtain high ribs by reducing the wall thickness of the pipe while reducing the outer diameter of the ribs is increased. 14. The method according to claim 13, characterized in that in the final rolling step, the outside diameter of the ribs is increased by approximately the same amount by which the wall thickness of the pipe is reduced. 15. The method according to claim 13 and 14, characterized in that that roll disks are provided in each device, which have a rounded cross-section on their circumference, whereby the radius from the first scroll wheel to the last scroll wheel increases by a factor of 2. 16. The method according to claim 13 to 15, characterized in that the discs in each arrangement are substantially conical have mutually converging side surfaces that are in pass over a rounded edge, the opening angle of the cone of rises about 165 to 170 ° on the first roll at the last roll disc. about 165 to 170 ° for the first rolling disk to about 178 ° 17. The method according to claim 13 to 16, characterized in that the profiles of corresponding discs in both arrangements are essentially identical. 18. The method according to claim 13 to 17, characterized in that that the pitch of the disks in the second arrangement is greater than the pitch of the disks in the first arrangement. 309832/0896 A 39 923 h
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k-35 19. The method according to claim 13 to 18, characterized in that that a different mandrel is used for each rolling step, that the diameter of the mandrel at the beginning of each Rolling step is slightly smaller than the inner diameter of the pipe and that the inner diameter of the pipe at the beginning of each rolling step it is gradually reduced until the inside of the pipe is below a rolling disc, which lies substantially in the middle of each of the two arrays of discs against the mandrel. 20. The method according to claim 13 to 19, characterized in that a few of the first slices one after the other Press twice to four times the amount into the material of the pipe by which the rest of the washers is pressed further into the material of the pipe. 21. Device for performing the method according to one or more of the preceding claims 4 to 20, characterized characterized in that it comprises a plurality of arrays of axially aligned disks which are successively used for Manufacture of ribs on a single tube are used that the rolling disks converging radially outward Side parts have that the disks have a rounded cross-section at their edge or circumference and that the profiles of corresponding disks in the assemblies are substantially identical. 22. The device according to claim 21, characterized in that the edge of each disc has a rounded cross-section and that the radius of curvature of the edge increases by a factor of 2 from the first slice to the last slice. 309832/0896 A 39 923 h
January 19, 1973 ^k " ³⁵ 23. Device according to claim 21 and 22, characterized in that that the radially outwardly converging side parts of the rolling disks on the input side of each arrangement one Include angles between about 165 to 170 and an angle of about 178 on the output side of the arrangement. 24. The device according to claim 21 to 23, characterized in that that the pitch of the rolling disks increases in successively effective arrangements. 25. The device according to claim 21 to 24, characterized in that the pitch of the rolling disks in each of the devices is uniform. 26. Device according to claim 21 to 25, characterized in that each device comprises several sets of discs, '' which are evenly distributed around the circumference of the pipe and are used simultaneously in each rolling step. 309832/0896 Blank page