US2779222A - Apparatus for making heat exchange tubes - Google Patents

Description

Jan. 29, 1957 R. c. EDWARDS APPARATUS FOR MAKING HEAT EXCHANGE TUBES Filed Jan. 5, 1954 Fig. l I RAY, C. E DWA R D5 1 INVENTOR.

FIG.IO

United States Patent 2,779,222 APPARATUS FOR HEAT EXCHANGE Ray C. Edwards, Pompton Plains, N. J. Application January 5, 1954, Serial No. 402,264 6 Claims. (Cl. 80-12) This invention relates to heat exchange tubes and more specifically to an apparatus for making a heat exchange tube particularly, though not exclusively, adapted for use in refrigerant evaporators or analogous devices.

More specifically the invention relates to an apparatus for making heat exchange tubes which are provided with internal radiation fins which radiate inwardly towards the axis of the tubes.

With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing an apparatus for making heat exchange tubes of a preferred form embodying the invention, and the features forming the invention will be specifically pointed out in the claims.

In the drawings:

Figure l is a fragmentary perspective view of the heat exchange tube constructed in accordance with the present invention.

Figure 2 is a fragmentary view partly in side elevation and partly in longitudinal section showing a heat exchange tube of the present invention prior to the formation of the external fins thereon.

Figure 3 is a cross section taken on the line 3-3 of Figure 2, showing in dotted lines the means employed in forming the extruded radiation fins on the inner surface of the tube.

Figure 4 is a fragmentary plan view of the fin extruding device.

Figure 5 is a longitudinal section through the fin extruding device and taken on the line 5-5 of Figure 4.

Figure 6 is a cross section taken on the line 6--6 of Figure 5.

Figure 7 is a composite view showing in section a set or series of extruding rollers used in the forming of the extruded internal fins.

Figure 8 is a view partly in side elevation and partly in longitudinal section showing part of the apparatus employed for extruding fins from the interior of the tube.

Figure 9 is an end view of the structure shown in Figure 8.

Figure 10 is a fragmentary plan view of a modified form of the tool or device used in extruding the internal fins.

Figure 11 is an end view of the tool or device shown in Figure 10 of the drawings.

Referring more specifically to the drawings, Figure 1 shows a perspective of a fragment of a complete heat exchange tube forming the subject matter of the present invention. This tube 1 is made of any fully annealed metal such as copper, or the like normally used in the construction of heat exchange tubes used in evaporators, condensers or analogous structures most generally employed in refrigerant apparatus although applicable for other uses. The tube 1 has a plurality of radiation fins 2 upon its outer surface. The fins 2 are formed by spirally winding a laterally crimped metallic ribbon or strip about the tube, in .edgewise engagement therewith in the manner and as described in either of my prior Patent Nos. 2,635,571 issued April 21, 1953, or 2,661,525 issued December 8, 1953. If it is desirable and the use to which the tube is to be put warrants it these external fins 2 may be wound flatwise upon the tube in the manner as shown in my application Serial No. 389,277 filed October 30, 1953. 'The tube 1 has a plurality of circumferentially spaced inwardly projecting longitudinally extending radiation fins 3 formed on its inner surface. These fins 3 extend longitudinally of the tube substantially parallel with the longitudinal axis of the tube so as to permit unimpeded flow of a coolant through the tube and the provision of these internal radiation fins 3 together with the external radiation fins 2 permit of a maximum heat transfer relationship through the tube.

The present invention also embraces the method of making or extruding the fins 3 together with the apparatus for so doing. The apparatus for extruding the fins 3 is shown in Figures 4'to 9 inclusive with the modified form of part of the apparatus shown in Figures 10 and 11.

Figures 4, 5 and -6 of the drawings show an arbor or mandrel 5 which has a plurality of longitudinally spaced diametrically extending openings 6 milled or otherwise cut therein. Metal extruding rollers 7 are rotatably mounted in the openings 6 on suitable pins 8. The rollers '7 have their perimeters grooved as clearly shown in Figures 4, 6 and 7 and they are arranged in sets with the grooves in the perimeters of all of the rollers in each set being identically cut. The rollers in the progressive sets are indicated as A, B and C in Figure '7 of the drawings, and it will be noted that the grooves 10 in the roller 7a are .of the maximum width and depth with the greatest degree .of angularity between their sidewalls and these rollers 7a which form the first set of rollers to engage the interior of the tube 1 are so shaped as to initially extrude metal from the inner wall of the tube 1 to form the internal fins .3. The grooves 11 of the rollers 7b and 7c in the successive sets vof rollers carried by the arbor 5 are so shaped that as they successively engage the metal extruded by the initial rollers 7a they extend and reduce the .cross sectional area of the extruded fins to form the fins 3 in their desired most practical set radiation shape and size.

The rollers of each set are disposed so that the perimeter of one of the rollers projects beyond the perimeter of the arbor 5 at one side of the axis .of the arbor while the other roller protrudes .at a diametrically opposed side of the arbor and thus when the arbor is forced through the tube 1 the fins are extruded at diametrically opposed portions of the interior of the tube. The rollers have a maximum width corresponding to a predetermined portionof the surface of the interior .of the tube as clearly shown in Figures 3, 4 and 6 of the drawings. In fabrication of tubes .of the type constituting the present invention a tube of a heavy wall preferably of a fully annealed material such as fully annealed copper or the like is employed; for example, a 1" O. D. diameter tube with a wall thickness of .050". The tube is encased wit in a metal block 15 (shown in Figures 8 and 9 of the drawings) which metal block is formed of two sections having recesses 16 in their inner facing sides which correspond exactly to the outside diameter .of the tube to be finned and the block 15 wholly encase the tube and rigidly support it so as to prevent distortion of the tube during the extruding of the internal fins thereon. The block 15 may be of such weight that it in itself will rigidly support the tube in place or if it is desired one of the sections of the block 15 may .be rigidly supported and the other section forced thereagainst and against a tube placed within the recesses in the block by pneumatic or hydraulic cylinder and piston structures 17 of any approved type which may be purchased upon the open market.

After the tube 1 is firmly and rigidly supported in the metal block 15 the arbor 5 is drawn or forced through the interior of the tube. The exterior diameter of the arbor which is a round rod is approximately .90" for a 1" O. D. tube and the rollers project beyond the outside diameter of the arbor sutficiently so that their grooved perimeters will engage the interior of the tube for extrudportions of the interior of the tube, said sets of rollers arranged in groups with all of the corresponding rollers in ing metal from its inner wall as the arbor is forced through the tube. As previously described, the perimeters of the rollers 7 are grooved to form ridges 18 which may or may not be out about a radius so that their periphery falls on the circumference of the wheel. The ridges of the rollers maintain a constant depth but the sides of the ridges of the successive rollers are progressively steeper resulting in a final roller in which the width of the groove cut in the roller would be approximately .050" and a depth corresponding to the height of the fin to be extruded. The complete internal finning of a tube requires successive passing of the tool or arbor through the tube at successively radially displaced positions until the full circumference of the interior of the tube is finned. The rolls may be so laid out and of such width that approximately 3, 4 or 5 passes of the arbor through the tube would be sufiicient to completely fin the internal surface of the tube.

However, the present invention also embraces the pro vision of the metal extruding fin forming tool or arbor which will completely fin the interior of the tube in one pass therethrough and such a tool is shown in Figures and 11 of the drawings. In the form of arbor shown in Figures 10 and 11 of the drawings a group of the initial extruding rollers 7a comprising a plurality of sets, for instance six sets, is provided with the rollers in each set spaced similarly to the rollers in the sets shown in Figure 5, i. e., with the perimeter of one roller of each set extending beyond the diameter of the arbor 5' at a point diametrically opposite that from which the perimeter of the other roller 7a proiects. In the grouping of the sets of rollers as shown in Fi ure 10 the rollers in the adiacent sets are disposed with their axes at an acute angle to the axes of the rollers in the adjacent set so that sufiicient sets of rollers are provided in each group and are so located that they will extrude metal from the entire circumference of the interior of the tube and thus with an arbor formed as shown in Figures 10 and 11 carrvin a plurality of groups of the successive rollers 7a, 7b and 70 a tube can be internally finned with one pass of the arb r or tool through the tube.

While Figure 7 shows three thin extruding and shaping rollers. it is to be understood of course that this number may be varied as required to properly extrude and sha e the fins and there may be 3. 4, 5 or any required number of rollers em loyed. e ch distinctive type arranged in sets as hereinabove described.

It will be underst od that the invention is not to be limited to the specific construction or arran ement of parts shown. but that thev mav be Widely modified within the invention defined by the claims.

What is claimed is:

1. Means for forming radiating fins on the inner sur face of a heat exchange tube comprising an arbor, a plurality of metal extruding rollers carried by said arbor and having their perimeters grooved to extrude metal from the inner surface of the tube and form extruded metal into fin shape, said rollers arranged in sets having corresponding grooved perimeters with the adjacent rollers of each set arranged to engage diametrically opposed portions of the interior of the tube.

2. Means for forming radiating fins on the inner surface of a heat exchange tube comprising an arbor, a plurality of metal extruding rollers carried by said arbor and having their perimeters grooved to extrude metal from the inner surface of the tube and form extruded metal into fin shape, said rollers arranged in sets having corresponding grooved perimeters with the adjacent rollers ofeach set arranged to engage diametrically opposed each successive set in each group having parallel axes. 3. Means for forming radiating fins on the inner surface of a heat exchange tube comprising an arbor, a plurality of metal extruding rollers carried by said arbor and having their perimeters grooved to extrude metal from the inner surface of the tube and form extruded metal into fin shape, said rollers arranged in sets having corresponding grooved perimeters with the adjacent rollers of each set arranged to engage diametrically opposed portions of the interior of the tube, the extruding rollers of the sets which successively engage the tube having their perimeter shaped to engage and further form the metal extruded by the rollers of the set which initially engages the tube.

4. Means for forming radiating fins on the inner surface of a heat exchange tube comprising an arbor, a plurality of metal extruding rollers carried by said arbor and having their perimeters grooved to extrude metal from the inner surface of the tube and form extruded metal into fin shape, said rollers arranged in sets having corresponding grooved perimeters with the adjacent rollers of each set arranged to engage diametrically opposed portions of the interior of the tube, the extruding rollers of the sets which successively engage the tube having their perimeter shaped to engage and further form the metal extruded by the rollers of the set which initially engages the tube, said sets of rollers arranged in groups with the axes of the rollers of the corresponding rollers in each group disposed at acute angles to the axes of the rollers of all other groups so as to engage and extrude metal from the entire internal surface of the tube in one pass of the arbor through the tubes.

5. Means for forming radiating fins on the inner surface of a heat exchange tube comprising an arbor, said arbor provided with a plurality of longitudinally spaced diametrically extending openings therein, metal extruding rollers rotatably mounted one in each of said openings, said rollers arranged in sets and having their perimeters grooved to extrude metal from the inner surface of a tube each in successive degrees of extrusion whereby the rollers in each set will form completed internal fins in a tube when drawn longitudinally through a tube, the rollers in one set projecting beyond the perimeter of the arbor diametrically opposite of the rollers in the other set whereby during the fin extruding action each set of rollers will form back up support for the diametrically opposed set of rollers to prevent distortion of the tube.

6. Means for forming radiating fins on the inner surface of a heat exchange tube as claimed in claim 5, wherein said sets of rollers are arranged in groups with the axes of the corresponding rollers of each group disposed at acute angles to the axes of rollers of all other groups so as to engage and extrude metal from the entire internal surface of the tube and form completed fins in the tube in one pass of the arbor through the tube.

References Cited in the file of this patent UNITED STATES PATENTS 1,472,719 Harvath Oct. 30, 1923 1,584,772 Hyde May 18, 1926 1,816,159 Smith July 28, 1931 1,865,575 Locke July 5, 1932 1,881,610 'Hyde Oct. 11, 1932 2,238,798 Lenk Apr. 15, 1941 2,467,668 Hallberg Apr. 19, 1949 2,508,518 Hill May 23, 1950 2,598,191 Penn May 27, 1952 2,627,652 SchWeller Feb. 10, 1953 FOREIGN PATENTS 16,340 Great Britain of 1899 111,528 Australia Sept. 26, 1940

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