US 2359926 A
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Description (OCR text may contain errors)
1944- w. E. M CULLOUGH ETAL 2,359,925
METHQD OF FORMING REFRIGERATION UNITS Filed Aug. 22, 1939 2 Sheets-Sheet l S 5 m b TUIT M Oct- 0, 1 w. E. M CULLOUGH EI'AL 2,359,926
METHOD OF FORMING REFRIGERATION UNITS Filed Aug. 22, 1939 2 Sheets-Sheet 2 INVENTORS.
Patented Oct. 10, 1944 METHOD OF FORMING REFRIGERATION UNITS William E. McCullough and Allen L. Goldsmith, Detroit, Mich, asaignora to Bohn Aluminum 8: Brass Corporation, Detroit, Micln, a corporation of Michigan Application August 22, 1939, Serial No. 291,382
1 Claim. (Cl. 29-1513) This invention relates to a method of manufacturing a refrigeration unit.
The refrigeration unit of this invention is made by securing a length of continuous aluminum tubing to a seamless aluminum sheet in such a manner as to form a continuous mass with the sheet. The attachment is preferably done while the sheet is in the fiat condition, after which the assembly may be bent in any way desired in forming the completed unit. This process has obvious advantages of simplicity and cheapness.
The preferred method of attachment is by an aluminum brazing process so that the completed device is a unit of aluminum material having all the advantages of strength, rapid heat fiow, etc., that are inherent with a one-piece construction.
Other objects and advantages of the invention will become apparent as the description proceeds.
While preferred forms of the invention are disclosed herein for purposes of illustration, it should be understood that various changes may be made without departing from the spirit of the invention as herein set forth and claimed.
In the drawings:
Fig. 1 is a perspective of an evaporator embodying the invention.
Fig. 2 is a plan of the tubing as first bent to preliminary shape.
Fig. 3 is a plan of the bent tubing assembled on the sheet and prior to brazing.
Fig. 4 is a section on line 4-4 of Fig. 3.
Fig. 5 is a view similar to Fig. 4 but showing the parts after brazing.
Fig. 6 is a perspective showing a modification of the invention.
Figs! is a plan showing the parts of Fig. 6 before they are bent to final shape.
Fig. 8 is a view similar to Fig, 4 but showing a modification.
Referring to the drawings more particularly, a preferred form of the refrigeration unit is illustrated in Fig. 1, the basic parts of which include a sheet i0 and a tube ll. Both of these parts are preferably formed of aluminum material, such as commercially pure aluminum or suitable alloys of aluminum.
The sheet i0 is a fiat-sided sheet, which means that it is of ordinary, plain sheet material having smooth opposite faces free from ridges or corrugations.
The sheet I! may be formed by rolling or any other method, and the tubing II is preferably extruded by a suitable process, such as that disclosed in U. S. Patent No. 2,031,008 to Schwerack.
The extruded tubing may take the shape illusll trated in Fig. 4 which shows the tubing as formed with a cylindrical opening I! and with a fiat wall it, the flat wall having a groove H which accommodates the welding rod.
In the preferred method of forming the refrigeration unit, the tubing II is first sinuously bent into the desired configuration, and a length of welding rod or wire i5 is placed in the groove it for the entire length of the groove. The welding rod I5 is formed of an aluminum material which has a melting point somewhat below the material of the sheet l0 and tube il. Thus where the sheet and tube are of commercially pure aluminum, the welding rod may be of an alloy including a small percentage of silicon, as, for ex.- ample, five percent of silicon, the remainder being substantially all aluminum. This silicon alloy has a melting point somewhat lower than the melting point of the commercially pure aluminum.
This tubing i I thus prepared is laid on the flat sheet l0 and the assembled unit is then brought to a temperature at which the rod 15 melts and fuses with the sheet l0 and tube l I, forming a single continuous mass of aluminum material as illustrated in Figure 5. This method of brazing aluminum is known in the art and is referred to merely as one method of uniting the tube and plate into a continuous mass.
After the tubing has been thus fused to the sheet ill, the resulting unit may be used to form the walls of a refrigerating unit. For example, in the form illustrated in Figure 1 the assembly is bent into substantially U-shape and a shelf Ii is then attached in a preferred manner. Suitable means are provided for attaching the pipes of a refrigerating system to the unit. Thus in the form illustrated in Figure 1, the ends I! of tube ii are left projecting beyond one edge of the sheet l0 and they are rounded up exteriorly or otherwise suitably formed for attachment to the refrigeration system.
The completed unit may be given an attractive and durable finish by means of anodic coating which is well-known in the art. This method, which involves electrolytic treatment in an acid bath, cannot be used where ferrous metals are present because the acid attacks the ferrous metals, but where the entire assembly is formed of aluminum as in the unit described above, the method may be used to form a wear-resistant and attractive coating on the entire unit, including the ice trays.
The refrigeration unit of this invention has a. number of advantages that will be apparent to those skilled in the art. One important advantage is that there are no joints in the single continuous piece of aluminum tubing, nor are there any Joints between the tubing and the aluminum. This construction provides for excellent heat transfer since there are no Joints to impede the flow of heat; there can be no breakage of joints due to different rates of thermal expansion; there can be no corrosion resulting from galvanic action due to the presence of dissimilar materials; and the entire unit can be given a uniform finish by means of anodic coating as explained above. The well-known advantages of aluminum in the matter of light weight and excellent heat conduction are too well known to need extended treatment.
It will also be clear to those skilled in the art that in the refrigerating unit of this invention it is possible to make practically any desired distribution of the cooling tube ll. Thus the runs of the tube H may for certain installations be placed closer together at places .where it is desired to have the greatest amount of heat extracted.
In the form previously described the continuous piece of tubing II was shown attached to a single aluminum sheet. However, the invention contemplates the attachment of a single piece of tubing to more than one sheet if desired. For example, in the form of the invention illustrated in Figure 6, the single continuous piece of tubing is attached not only to the walls of the refrigerating unit but also to the shelf. v
In forming this type of unit the tubing H is sinuously bent so as to cover one side of the sheet IS, an intermediate part is of the tubing being extended beyond the lateral edge of sheet 18 and bent so as to extend over one face of the flat sheet 20 which is to form the shelf. The tubing is bent and assembled with its flat face in contact with the underside of the sheet l8, and its extended part I9 is twisted so as to bring the fiat face I3 of the tubing into contact with the upper surface of sheet 20. These parts are then brazed together with the aluminum brazing rod as previously explained.
In assembling this unit the flat sheet 18 is bent upwardly into U-shape along the dot-anddash lines 2| in Figure 7, and the edges of sheet 20 are bent downwardly along the dot-anddash lines 22. The part of the tubing ll extending between sheets 18 and 20 is then bent so as to permit the sheet 20 to be assembled inside of sheet It in a suitable position for the shelf. The edges of the shelf may then be secured to the sheet I! in any preferred manner.
It will be seen that in the form illustrated in Figure 6 the runs of tubing II are disposed lengthwise of the unit, whereas in the form illustrated in Figure 1 the runs are disposed crosswise of the unit. These two arrangements are but illustrative examples of the wide variety of forms in which the tubing H can be attached to sheets forming refrigerating units. It will be understood, of course, that for some installations the sheets to which the tubing has been attached can be left flat or they may be bent into forms other than-those illustrated herein. It should also be understood that the aluminum tubing may take other forms aside from the one illustrated. Thus as shown in Figure 8, the tubing may have one or more flanges 23 which may be left continuous or which may be cut away to form a series of attaching tabs. Figure 8 also shows that it is possible to extrude the tubing with fins 24 which increase the radiating area of the tube wall. Other arrangements aside from the groove l4 may be used to hold the brazing material in place during the heating operation.
While the aluminum brazing process has been disclosed as the presently preferred method of fusing the tube to the sheet, it will, of course, be understood that any other method can be used that will result in coalescing the sheet and tube into a single, continuous mass of metal. And where the aluminum brazing process is used, other equivalent arrangements may be made for supplying the brazing material. For example the brazing material may be in the form of a ribbon or film between the tube and the plate.
The phrase aluminum material as used herein refers to commercially pure aluminum or to any alloy consisting predominantly of aluminum, and which, due to its composition does not develop an appreciable galvanic current in the presence of weak electrolytes and commercially pure aluminum.
The method of forming a refrigeration unit which comprises extruding a length of tubing of aluminum material having a fiat side, bending the length of tubing into a flat sinuous form, placing the tubing with part of its flat side in contact with the under surface of a first sheet of aluminum material and with part of its flat side in contact with the upper surface of a second sheet of aluminummaterial, the two sheets being spaced apart, brazing the tubing to the sheets by means of brazing rod formed of aluminum material, bending said first sheet to form walls of a refrigeration unit, and bending said second sheet Lung: place to form the shelf of the refrigeration ALLEN L. GOLDSMITH. WILLIAM E. McCULLOUGH.