US 3683487 A
Tube-in sheet material in which the tube is corrugated for enabling forming the material, as by bending, without collapse of the tube, and a method of making such material by inflation of a portion of composite sheet metal stock in dies having a corrugated tube-forming cavity.
Description (OCR text may contain errors)
llnited States Patent Sherman [4 1 Aug. 15, 1972  A METHOD OF MAKING AN 1,992,835 2/1935 Newman ..29/480 INFLATED PRODUCT WITH A BEND 2,990,608 711961 Manning ..294709 3,114,202 12 1963 Wenger ..29 470.9 [721 invent edemk 34 West 3,340,589 9/1967 Jaeger ..29/471.1 x
St., Attleboro, Mass. 02703 22 Fil d; March 24 1971 Primary Examiner-John F. Campbell Assistant Examiner-Richard Bernard Lazarus PP 9 Attorney-Harold Levine, Edward J. Connors, Jr.,
Related us. Applicafion Data .slta'gs McAndrews, John ,A. Bang and Gerald B. Ep-  Continuation of Ser. No. 761,243, Sept. 20,
1968, abandoned. ABSTRACT Tube-in sheet material in which the tube is corrugated U-S- CI. ..29/470.9, for enabling forming the material as bending Int. Cl. without cullapse of the tube and a method of Fidd 588mb /480, such material by inflation of a portion of composite 29/4709, 471.1 sheet metal stock in dies having a corrugated tubeforming cavity.  References Cited 6 Claims 6 Drawing Fi UNITED STATES PATENTS Dreckmann ..285/l 83 METHOD OF MAKING AN INFLATED PRODUCT WITH A BEND This application is a continuation of application Ser. No. 761,243 filed Sept. 20, 1968 and now abandoned.
This invention relates to tube-in-sheet material and methods of making it, and more particularly to such material adapted for forming, as by bending without I collapse of the tube or tubes in the material, and methods of making such bendable tube-in-sheet material. a v
The invention is particularly concerned with material referred to as tube-in-sheet material made as disclosed in U.S. Pat. Nos. 3,346,936 and 3,371,399 and generally comprising two sheets of metal disposed faceto-face, having expanded portions (expanded by inflation) forming tubes integrally in the material, the sheets being interfacially bonded. It is often desired to shape such material by operations involving bending, and difficulties have heretofore ensued because bending caused collapse of the tubes on the outside of the bend and/or uncontrolled wrinkling of the tubes on the inside of the bend. The principal object of this invention is the provision of composite tube-in-sheet material which may be bent without such collapse or wrinkling of the tubes.
Generally, composite material of this invention comprises two sheets of metal disposed face-to-face and having an expanded portion forming a tube and interfacially bonded in the area thereof lying outward of the tube. The tube has a corrugated or bellows formation, which enables the material to be bent transversely to the tube without collapse or other undesirable deformation of the tube. The composite material is made, according to this invention, generally by a method comprising disposing the individual sheets of metal in face-to-face relation, placing them between dies formed to provide a tube-forming cavity for expansion of a portion of at least one sheet to form the tube, the cavity having a corrugated formation, and inflating said portion to form a tube with a corrugated formation corresponding to the cavity formation. Other objects and features will be in part apparent and in part pointed out hereinafter.
The invention accordingly comprises the constructions and methods hereinafter described, the scope of the invention being indicated in the following claims.
In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,
FIG. 1 is a perspective showing composite material made according to this invention, showing the corrugated forrnation of a tube in the material;
FIG. 2 is a section on line 22 of FIG. 1; 7
FIG. 3is a cross section corresponding to FIG. 2 showing the material shaped by bending transversely to the corrugated tube;
FIG. 4 is a section showing two sheets between forming dies for inflation thereof to form a tube;
FIG. 5 is a section on line 55 of FIG. 4; and
FIG. 6 is a section similar to FIG. 5 showing inflation of the composite material in the dies.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.
Referring to the drawings, there is indicated generally at 1 a portion of bendable composite sheet material of this invention having a tube 3 integrally formed therein by inflation. The composite tube-insheet material comprises two sheets 5 and 7 of malleable metal disposed in face-to-face relation and bonded together at 9 in the area lying outward of the tube 3. The tube, which is formed by expanded portions of both sheets, has a corrugated formation constituted by alternating annular ridges l1 and valleys 13 in the expanded portions of thesheets. The ridges in each of the portions are opposite one another and the valleys in each of the portions are opposite one another. The corrugated formation of the tube constitutes a portion of the tube as a bellows whereby the composite material may be shaped as by bending transversely to the tube, as seen in FIG. 3, without collapse or other undesirable deformation of the tube.
As appears from FIG. 3, the corrugated or bellows formation of the tube prevents it from collapsing and/or wrinkling when the tube-in-sheet composite material is bent transversely to the tube, noting that the corrugations permit stretching of the tube on the outside of the bend and controlled accordion folding of the tube on the inside of the bend (i.e., the ridges II and valleys 13 on the outside of the bend become less well defined upon bending, and the ridges and valleys on the inside of the bend become more sharply defined). Thus, the tube remains unobstructed after bending. Heretofore, the tubes in conventional tube-in-sheet material have tended to collapse, wrinkle or otherwise undesirably deform upon bending.
While the tube-in-sheet material shown is illustrated with both of its component sheets having corrugated expanded portions, it will be understood that the present invention contemplates that only one of the sheets might be so expanded to form a corrugated tube with the other sheet remaining flat.
It will be understood that the material 1 may be made with a plurality of corrugated tubes, and that the entire length or only selected portions of the length of each tube may be corrugated. Also, the number of corrugations along the length of the tube may be varied as desired.
In the method of making tube-in-sheet material having a corrugated tube according to this invention, sheets of initially flat malleable metal such as steel are disposed in face-to-face relation and bonded together. The sheets may be solid-phase bonded together by processes such as described, for example, in Boessenkool et al., US. Pat. No. 2,691,815. Solid-phase bonding is accomplished by carefully cleaning the faces of the sheets, as by wire brushing, and then green-bonding the faces by squeezing them together with a reduction in thickness by means of a rolling mill. The green-bond may be partially improved by heat treating. This also softens the metal to facilitate the subsequent inflation.
The bonded flat sheets, which may be cut from lengths of green-bonded composite steel strip, are placed between matrix dies 15 and 17, as shown in FIGS. 4-6. Each die is formed with an incised matrix recess cavity 19 for expansion of portions of both sheets to form the tube. The cavity has a corrugated formation with ridges 21 and valleys 23. Guide means such as shown at 25 may be used for proper registration between the dies and the bonded sheets. The dies are then held or clamped together by pressure as shown by the arrows in FIG. 5. A nipple or needle 27 is then forced between the sheets 5 and 7 at a location corresponding to the cavities of the dies. Hydraulic fluid under high pressure is then injected between the sheets for inflation of the portions of the sheets to form the tube 3, as is shown in FIG. 6 wherein arrows represent the inflating action of the hydraulic fluid. After inflation, the pressure is released and the nipple is removed. The inflated green-bonded composite tube-in-sheet material may then be placed in a furnace for heat-treating to improve the green bond by sintering.
Alternatively, in accordance with the process described in US. Pat. No. 3,371,399 noted above, prior to bonding the sheets 5 and 7 together, a pattern of a substance containing a metal oxide may be applied to the faces of the sheets in register with those portions of the sheets which will be expanded to form the tube. The sheets are then bonded together exclusive of the pattern and heated between the dies in a reducing atmosphere penetrable through at least one of the sheets to reduce the oxide and release a gaseous product in the area of the pattern for inflating the portions of the sheets to form the tube with corrugations.
The completed tube-in-sheet product as shown in FIG. 1 may then be formed, bent or shaped as desired without danger of collapsing or undesirably deforming the tube to enable the use of the material as desired. For example, the bendable product may find use as a cooling element in refrigeration units, or it may be employed for heating purposes. The corrugation or bellows formation of the tube or tubes in the material thus increases the utilization of tube-in-sheet material by providing such a material which may be bent with a small radius of curvature without causing collapse of the tube or decreasing its strength because of undesirable collapse or other deformation. This also insures against the possibility of excessive fluid pressure drop due to collapse of the tube at the bend when the material is used for the circulation of fluid. It will be observed that, in the bent tube-in-sheet material, the regular symmetrical form of the tube is substantially preserved in the bend portion of the material, and a high moment of inertia of the tube cross section is preserved for increased strength. Also, the hydraulic or pneumatic strength of the tube is preserved at the bend by elimination of local stress that would otherwise be caused by uncontrolled wrinkling of the tube on the inside of the bend.
In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.
As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
1. The method of making a composite metal tube-insheet material having a bend therein and having a tube formed integrally within said composite material extending around said bend, said method comprising the steps of interfacially bonding two sheets of metal together, placing said bonded metal sheets between die portions which cooperate to form a tubular cavity and WIllCh have alterna e ridge and valley portions extending transversely of the axis of said tubular cavity defining a corrugated formation as at least part of said tubular cavity, inflating a portion of at least one of said sheets of metal into said tubular cavity to form a tubein-sheet material having a tube extending between said sheets of metal and to provide a corrugated formation in said tube corresponding in shape to said corrugated formation of said tubular die cavity, and forming a bend in said tube-in-sheet material extending through said corrugated formation of said tube transversely of the axis of said tube.
2. The method of claim 1 wherein the sheets are solid-phase bonded together.
3. The method of claim 2 wherein the sheets are green-bonded prior to placement between the dies and heat treated subsequent to formation of the tube having the corrugated formation to improve the green bond.
4. The method of claim 2 wherein each die is formed with a recess to provide the cavity for expansion of portions of both sheets to form the tube, the recess in each die having a corrugated formation, and said portions of both sheets being inflated to form the tube with a corrugated formation corresponding to that of said recesses.
5. The method of claim 2 wherein said portion is inflated by forcing a fluid between the sheets.
6. The method of claim 2 wherein a pattern of a substance containing an oxide is applied to the face of at least one of said sheets in said portion between the dies, said sheets are solid-phase bonded together exclusive of said pattern, and the sheets are heated together in a reducing atmosphere penetrable through at least one of the sheets to reduce the oxide and release a gaseous product for inflating said portion to form the tube.