WO1995005571B1

WO1995005571B1 - Radiator tube and method and apparatus for forming same

Info

Publication number: WO1995005571B1
Application number: PCT/US1994/008851
Authority: WO
Filing date: 1994-08-04
Publication date: 1995-04-13

Abstract

A radiator tube (10) having a flattened oval shape has pairs of opposed turbulator dimples (20) formed in its principal heat transfer surfaces (12, 14), which dimples extend inwardly and meet in the tube interior to define a plurality of pillars. First and second generally continuous curved surfaces (16, 18) interconnect and are integrally formed with the principal heat transfer surfaces (12, 14). In a method of forming a radiator tube (10) having a flattened oval shape, turbulator dimples (20) are formed in a generally planar metal strip (30) in a pattern which is symmetric about a longitudinal line (36). The strip (30) is roll formed into tubing (50) having a circular cross section, with its opposed side edges (32) abutting and in alignment. The side edges (32) are simultaneously compressed and welded together by heating at the melting point of the parent metal using a high frequency induction current, to form a solderless joint (52) between them. Finally, the tubing (50) is transformed by reduction and breakdown rolls to a flattened oval cross section. Apparatus for forming the tubing includes first and second modular cylindrical rolls (120, 122) mounted respectively on first and second parallel shafts (110, 112). The first roll (120) includes disks (152) with male punches (140) formed thereon, while the second roll (122) includes disks (152) with female dies or sections (142) formed therein in alignment with the male punches (140). The males punches (140) and female sections (142) are maintained in alignment by phasing gears (150) on the shafts (110, 112).

Claims

AMENDED CLAIMS [received by the International Bureau on 16 March 1995 ( 16.03.95) original claims 1 -13 replaced by amended claims 1-17 (6 pages) ]

1. A radiator tube having a flattened oval shape comprising:

opposed first and second generally planar, principal heat transfer surfaces;

a first generally continuous curved surface interconnecting and integrally formed with said first and second principal heat transfer surfaces; and a second generally continuous curved surface interconnecting and integrally formed with said first and second principal heat transfer surfaces, said first and second principal heat transfer surfaces and said first and second generally continuous surfaces defining a tube interior;

said first and second principal heat transfer surfaces having a plurality of pairs of opposed turbulator dimples formed therein and extending inwardly therefrom, said turbulator dimples being formed with flattened upper faces which are generally rectangular in configuration, with rounded corners, and said pairs of opposed turbulator dimples meeting in said tube interior with said upper faces aligned with and contacting each other to define a plurality of pillars.

2. The radiator tube of claim 1 , wherein said surfaces have a thickness of less than 0.23 mm.

3. The radiator tube of claim 1, wherein said second curved surface includes a longitudinal, welded leak-free seam.

4. The radiator tube of claim J , wherein said faces of said turbulator dimples are generally square,

5. The radiator tube of claim 1, wherein said radiator tube has end diameters between 1.905 mm and 2.032 mm. and has an outside center dimension between 1.95 mm and 2.03 mm, and wherein said turbulator dimples when formed have a height between 0.250 mm and 0.760 mm.

6. The radiator tube of claim 5, wherein said faces of said turbulator dimples each has a length dimension of between 0.30 mm and 1.90 mm and a width dimension of between 0.30 mm to 2.05 mm.

7. The radiator tube of claim 6, wherein said turbulator dimples are formed on centerlincs separated by a distance of between 5.296 mm and 12.24 mm.

8. A method of forming a radiator tube having a flattened oval shape, comprising the steps of:

(a) providing a generally planar strip of a metal material comprising a parent metal and a second metal, the strip having opposed side edges and a longitudinal line intermediate the side edges;

(b) following said step (a), forming turbulator dimples in the strip on either side of the longitudinal line to define a pattern of dimples which is symmetric about the longitudinal line;

(c) following said step (b), roll forming the strip to form it into a tube of circular cross-section with the opposed side edges abutting and in alignment;

(d) following said step (c), compressing the opposed side edges together and simultaneously welding them together by heating at the melting point of the parent metal using a high frequency induction current, to form a solderless joint between the side edges; and

(e) following said step (d), transforming the cross-section of the tube from circular to a flattened oval having opposed first and second generally planar, principal heat transfer surfaces, a first generally continuous curved surface having the longitudinal line approximately at its apex and interconnecting and the first and second principal heat transfer surfaces, and a second generally continuous curved surface opposite the first curved surface and interconnecting the first and second heat transfer surfaces, the second curved surface having the solderless joint therein.

9. The method of claim 8, wherein said step of forming the turbulator dimples comprises passing the strip between a pair of rotating cylindrical rolls a predetermined distance apart, one of the rolls having male punches formed thereon and the other of the rolls having female sections formed therein in alignment with the male punches.

10. The method of claim 9, wherein said step of forming the turbulator dimples further comprises using phasing gears to maintain alignment of the male punches with the female sections.

11. Apparatus for forming a radiator tube having a flattened oval shape and interior pillars, comprising:

first and second parallel, rotating shafts;

a first roll mounted on said first shaft, said first roll having a generally cylindrical outer surface having male punches formed thereon;

a second roll mounted on said second shaft, said second roll having a generally cylindrical outer surface having female sections formed therein in alignment with said male punches; and phasing gears mounted on said first and second shafts, to maintain alignment of said male punches with said female sections.

12. The apparatus of claim 11, wherein said first and second rolls each comprises a hub and a plurality of annular pillar disks mounted on said hub, said male punches being formed on said pillar disks of said first roll and said female sections being formed in said pillar disks of said second roll.

13. The apparatus of claim 12, wherein said first and second rolls further comprise a plurality of annular space disks, said spacer disks separating said pillar disks.

14. The apparatus of claim 11, further comprising adjusting means for adjusting the separation between said first and second rolls.

15. The apparatus of claim 11, further comprising:

first and second spaced apart stands, said first and second shafts being mounted for rotation between said first and second stands and said second shaft also being mounted between said first and second stands for parallel movement relative to said first shaft; and

adjusting means for moving said second shaft in a parallel direction relative to said first shaft.

16. The apparatus of claim 15, wherein said adjusting means comprises: a cover plate fixedly attached to and extending between said first and second stands;

first and second bearing blocks movably mounted in said first and second stands, respectively, between said first roll and said cover plate, said second shaft being rotatably mounted in said first and second bearing blocks;

an adjusting plate fixedly attached to said first and second bearing blocks and interposed between said first and second bearing blocks and said cover plate;

an adjusting nut rotatably mounted to said cover plate; and a threaded rod fixedly attached to said adjusting plate and extending through said adjusting nut.

17. The apparatus of claim 16, wherein said first and second stands each have a hole extending therethrough intermediate said first and second shafts, said apparatus further comprising a pair of stop pins insertable in said holes under said first and second bearing plates for preventing inward movement of said second roll towards said first roll.