US2818483A - Method and apparatus for preheating can body side seams - Google Patents

Description

Dec. 31, 1957 LE ROY o. BLUME METHOD AND APPARATUS FOR PREHEATING CAN BODY SIDE SEAMS Filed Aug. 11, 1955 2 Sheets-Sheet 1 WO N N b m w b I I n I I I u v In MH A w ww m V A z 0 a m. .e L

ATTORNEYS Dec. 31, 1957 LE ROY o. BLUME METHOD AND APPARATUS FOR FREE- EATING CAN BODY SIDE SEAMS 2 Sheets-Sheet 2 Filed Aug. 11, 1955 A'BY dim/0 METHOD AND APPARATUS FOR PREHEATING CAN BODY SIDE SEAMS LeRoy 0. Blume, Chicago, 111., assignor to Continental Can Company, Inc., New York, N. Y., a corporation of New York Application August 11, 1955, Serial No. 527,830

Claims. (CI. 219-1041) The invention relates generally tov can manufacture and more specifically to the, making of can bodies having soldered side seams of any of the various types known to the industry. Before such side seams are solder bonded it is desirable to preheat them to a hig degree in order to facilitate efficient introduction of the bonding solder into the side seam structures, and the present invention seeks to provide a new and improved method of and apparatus for accomplishing such preheating.

One object of the invention has been to utilize a conventional form of high frequency generator in bringing about the application of the required heat to the side seams. Such generators are commonly used with a high frequency coil for heating a work-piece which is to be soldered, brazed or welded. Heat is not conducted or radiated from the high frequency coil to the work-piece to accomplish the desired heating of the latter and in fact the coil is commonly water-cooled. On the contrary, the heating is accomplished by the action of the magnetic field created by the coil, Therefore, the provision of a high frequency coil which would create a magnetic field of such form as to be capable of effective concentration and localization on can body side seams, has been a most importantobject of the invention. This object has been attained by the provision of a high frequency coil having an elongated reach which creates a correspondingly elongated tubular magnetic field around itself. Thus, an apparatus and method are made possible, wherein the can bodies with their side seams aligned, are fed and guided along a path unidirectional with the elongated coil reach, and the side seams are maintained within the tubular magnetic field during the travel of the can bodies along said path. In this manner the action of the tubular magnetic field will be eonoentrated and localized on the seam portions of the can bodies where required, to produce the concentrated heating preparatory to solder-bonding.

The preferred high frequency coil is formed from copper tubing of about 5 diameter. This coil comprises the aforesaid elongated reach, in rectilinear form, two return bends, one at each end of said elongated reach, two relatively short aligned reaches paralleling the elongated reach and extending inwardly toward each other from said return bends, and two terminal portions laterally bent from the adjacent ends of said relatively short reaches and extending away from said elongated rectilinear reach. Only the magnetic field surrounding the elongated rectilinear reach is utilized for heating the can body side seems and it has been found that the best results are obtained when this reach is about 6' long, with its longitudinal center spaced about 2 /1" from the longitudinal center of the relatively short reaches. This specific coil construction has well attained the desired ends and has made possible the heating in one second and to a highly adequate temperature, the side warns of can bodies travelling at a rate of 600 per minute.

Another object has been to make novel provision to insure that the, can body guiding means. shall have no 2,818,483 Patented Dec. 31, 1957 "ice harmful effect upon the magnetic field created around the effective reach of the high frequency coil.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings.

in the drawings:

Figure l of the accompanying drawings is a somewhat diagrammatic top plan view illustrating the invention.

Figure 2 is an enlarged transverse sectional view illustrating a can body passing over the seam preheating coil, for example on line 22 of Figure 1.

Figure 3 is a perspective view of the seam preheating coil.

Figure 4 is a transverse sectional view on line 4-4 of Figure 3, diagrammatically illustrating the magnetic field around the coil reaches, and also illustrating diagrammatically a can body side seam within the magnetic field of the elongated coil reach.

Figure 5 is a diagram giving one example of a high frequency generator embodying the seam preheating coil of the present invention.

Preferences have been disclosed in the drawings and will be rather specifically described but attention is invited to the possibility of making variations within the scope of the invention.

In Figure l a portion 10 of the arch of a can body maker is shown. Under this arch, the can bodies are shaped into cylindrical form and their side seams are bumped in the well known manner. Spaced from the usual stub horn 11 on which the shaped and bumped can bodies 12 are fed from the body maker 10 (by conven tional means), a solder applying means 13 (forming no part of the present invention) has been shown. From the stub horn 11 to and beyond the solder applying means 13, an outside horse, generally designated at 14, is illustrated. Operable longitudinally over the horse 14 in the usual way, is a feeder chain 15 having the customary feeder lugs 16 which feed the can bodies 12 along the path defined by the horse 14. Under and parallel with this path, the high frequency seam preheating coil 17 is mounted, said coil 17 being connected with a high frequency generator 18 of any adequate form, one example being diagrammatically shown in Figure 5, later referred to.

Before proceeding to a detailed description of the coil 17, it will be well to explain that the outside horse 14 should be of non-magnetic material in the region of the coil 17 to prevent it from interfering with the magnetic field relied upon to heat the can seams 19. For example, the lower portion of the horse 14 may be formed by two chrome-plated can body supporting rails 20 of hard copper or bronze (Figure 2). Guide rods 21 may constitute the upper portion of the horse.

The coil 17 is formed from copper tubing of about diameter and receives cooling water in the usual way. This coil comprises an elongated rectilinear reach 22, two return bends 23, two relatively short aligned reaches 24, disposed in parallel spaced relation to the reach 22, and two terminal portions 25, said reaches, return bends and terminal portions preferably being dimensioned and relatively placed as follows. The elongated reach 22 is about 6 in length; the return bends 23 are at the ends of this reach 22; the aligned reaches 24 extend inwardly from said return bends 25 and their longitudinal centers parallel and are spaced about 2 /2" from the longitudinal center of the elongated reach 22, and the terminal portions 25 which connect with the generator 18 are laterally bent from the inner ends of said aligned reaches 24 and extend away from the elongated 3 reach 22. All of the elements 22, 23, 24 and 2.5 lie in a single horizontal plane in the present disclosure.

The elongated rectilinear reach 22 is disposed longitudinally of the can body feed path and in close proximity to the side seams 19, which seams are in longitudinal alignment as the can bodies 12 leave the body maker and are maintained in this alignment as the bodies travel along the horse 14. In the resent disclosure, the seams 19 are at the lower sides of the can bodies 12 and therefore the elongated coil reach 22 is under the path along which said bodies are fed and guided.

When the generator 13 is in operation, the elongated reach 22 creates tubular magnetic field 26 (Figure 4) around itself, said field being composed of concentric cir- .cular lines of force 27. The body side seams 19 are maintained in this magnetic field 26 throughout their travel over the reach 22, and it is the action of this field which heats the seams 19. The heating energy is thus concentrated and localized on the seam portions of the can bodies and is not wasted on large adjacent portions of said bodies. It is to accomplish this, that tubing of the particular form and placement herein disclosed is employed.

During creation of the field 26, a similar field 28 (Figure 4) is created around each of the relatively short coil reaches 24 but these fields 28 are not utilized in the heating of the cans.

The coil 17 may be mounted in any suitable manner. A horizontally elongated flat support is shown and this support may be of any appropriate insulating material, wood for example. The upper side of the support 29 is grooved at 29a for reception of the coil 17 and surrounding insulating means. This insulating means may consist of insulating varnish and mica tape 31. The coil, thus shielded, is secured in the grooves 2% by cement 32.

Operation With the high frequency generator 1% in operation and its output properly regulated, the coil reach 22 creates the tubular magnetic field 26 which surrounds and extends from end to end of said reach The can bodies 12 are fed along the horse M by the feeder chain lugs 16 and the side seams are maintained in alignment directly over the coil reach 22. Thus during the entire travel of the can bodies over coil ll, the seams 19 cut through the magnetic field 26 and the circular lines of force 217 travel transversely through said seams 19. The action of this field thus very rapidly and intensively heats the seams and heating is concentrated and localized on the seam portions of the can bodies.

When using 300 amperes, 22% volts and a frequency of 450 kilocycles in the coil itself and feeding the can bodies .12 at the rate of 600 per minute, it has been possible to continuously heat the side seams 19 to a' degree entirely adequate to prepare said seams for highly efficient solder bonding. In attaining these results, a stand ard Westinghouse radio frequency generator (induction heater) has been used, including a rheostat for varying the energy output of the coil 17, making it possible to vary the temperature to which the seams will be heated. In Figure 1, a control knob for the rheostat of the generator 18, is shown at 33.

Any suitable high frequency generator may, of course, be employed and Figure 5 diagrammatically illustrates such a generator and the coil 17. As this generator is well known, it will sufiice to merely identify its principal elements as follows:

34Conductor to high voltage rectifier.

35-Plate by-pass capacitor.

36Oscillator tube.

37--Filament by-pass capacitor.

38-Conductor to filament terminal board. 39-Conductor to grid resistors.

40Conducto r to ground on filament terminal board.

4 41-P1ate choke. 42-Plate blocking capacitor. 43Tank capacitor. 44-Tank coil. 45-Stabilizer resistor. 46-Grid coil. 47--Grid by-pass capacitor. 48Cooling water inlet. 49Cooling water outlet.

From the foregoing, it will be seen that novel and advantageous provision has been made for carrying out the desired end. However, attention is again directed to the fact that variations may be made in the example method and apparatus disclosures herein without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In a can body side seam heating means, means for longitudinally feeding and guiding the can bodies along a predetermined path in longitudinally spaced relation and with their side seams in alignment, at high frequency coil having an elongated reach directly centered along the aligned side seams and having a length greater than the combined length of a plurality of the can bodies and which creates a tubular magnetic field around itself, said elongated coil reach being disposed unidirectionally with said path and being transversely spaced from said path, and means mounting said elongated coil reach in such position that the can body scams will travel longitudinally through said tubular magnetic field as the can bodies travel along said path, and said guiding and feeding means being constructed to feed the can bodies along a rectilinear path, said elongated coil reach being rectilinear and parallel with said path, said guiding and feeding means and said elongated rectilinear coil reach being so related as to dispose the can body seams in close proximity to but spaced slightly from said elongated rectilinear coil reach during travel of the can bodies along said rectilinear path.

2. A structure as specified in claim 1; said high frequency coil comprising said elongated reach in rectilinear form, return bends at the ends of said elongated rectilinear reach respectively and disposed in the same plane, relatively short aligned reaches extending inwardly toward each other from said return bends respectively and spaced laterally from said elongated rectilinear reach and terminal portions bent laterally from the inner ends of said relatively short reaches and extending away from said elongated rectilinear reach; said coil being formed from copper tubing of about in diameter, said elongated recti-linear reach being substantially 6' long and having its longitudinal center parallel and spaced about 2 /2 from the longitudinal center of said relatively short reaches.

3. A structure as specified in claim 1; said high frequency coil comprising said elongated reach in rectilinear form, return bends at the ends of said elongated rectilinear reach respectively and disposed in the same plane, relatively short aligned reaches extending inwardly toward each other from said return bends respectively and spaced laterally from said elongated rectilinear reach and terminal portions bent laterally from the inner ends of said relatively short reaches and extending away from said elongated rectilinear reach; said mounting means comprising an elongated insulating base having grooves in which said elongated rectilinear reach and said relatively short reaches are confined.

lengths of, a plurality of can bodies and which creates a tubular magnetic field around itself; the steps otaligning the side seams of the can bodies, longitudinally feeding the can bodies in longitudinally spaced relation on a path parallel with and transversely spaced from said elongated rectilinear coil reach and directly centered along said reach, and maintaining the aligned seams within said tubular magnetic field and in closely spaced proximity to said elongated rectilinear coil reach during travel of the can bodies along said path.

References Cited in the file of this patent UNITED STATES PATENTS

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