US1745585A - Method of making metallic bellows - Google Patents

Description

Feb. 4, 1930. A. o. SCHARER METHOD OF MAKING METALLIC BELLOWS Filed Sept. 17. 1925 Air Pump IXVENTOR Arnoki ofichurer Patented Feb. 4, 1930 UNITED "STATES PATENT OFFICE ARNOLD O. SCHARER, OF CLEVELAND, OHIO, ASSIGNOR TO THE BISHOP & BABCOCK COMPANY, OF CLEVELAND, OHIO, A. CORPORATION 01 OHIO METEOD OF MAKING METALLIC BELLOWS Application filed September 17, 1925. Serial No. 56,875.

The present invention relates to a method of making metallic bellows, and is more particularly directed to an improved method of converting angular corrugations previously 5 formed in a thin tubular wall into substantially parallel corrugations with a minlmum of effect and time and in such a way as to produce substantially parallel corrugations and prevent any irregularities or cocking of one or more of the corrugations, as has been the trouble with methodspreviously used for this purpose. A further object of the invention is the provision of a combined method for thus converting angular into parallel corrugations by collapsing of the tube len h while at the same time testing the meta l 1c bellows for any minute leaks or openings 1n the tube wall which may. have been formed during the previous manufacturing steps. To the accomplishment of the foregoing and relatedends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawing and the following description set forth in detail certain means and one mode of carrying out the invention, such disclosed means and mode illustrating, however, but one of various ways in whlch the principle of the invention may be used.

In said annexed drawing Fig. 1 is a view more or less diagrammatic in character showing one form of apparatus adapted to carry outmy improved method, in which apparatus there is positioned an extended corrugated tubular wall ready for collapsing; and Fig. 2 is a side elevation of a metallic bellows after this collasping and testing operation.

One method of manufacturing metallic bellows consists in forming broad corrugations in a cylindrical tube, the corrugations having angularly related sides and being broad relative to the desired breadth of corrugation which is finally desired in the bellows, after which these corrugations are converted into parallel sided ones by a longitudinal collapsing operation which slightly increases the outside diameter of the corrugation, decresaes the inside diameter and very greatly narrows the angular opening in both the outer and inner corrugations by a combined bending and stretching action. This operation may be performed by various methods, one of which is described in a copendmg application filed by William R. Zimmerman, erial No. 60,786, and the method there described is entirely satisfactory, except that it requires a certain amount of time to dispose, collapse, and then remove each of the partially corrugated bellows from the collapsing apparatus since the bellows must be mounted about an internal die, after which a plunger must be brought down into contact with one end of the bellows to perform this collapsing step. The present method has been found to save considerable time over that in the above-named application, and at the same time to effect atesting of the bellows which is substantially the equivalent of the service to which the majority of such bellows are put, that is, the testing pressure is substantially as high as the pressures in use to which the bellows is subjected.

My improved method of collapsing consists, briefly stated, in mounting a bellows having one closed end with its open end in position against a suction plate formed in suitable material to give a tight joint at this end of the bellows, after which suction is applied to the interior of the bellows to produce as high a vacuum as possible therein, thus allowing the atmospheric pressure acting upon the closed end of the bellows to collapse the bellows without any other means. It will be apparent that the total pressure acting to collapse the bellows is substantially the product of the number of square inches in the closed end multiplied by the atmospheric pressure minus the internal pressure still remaining in the bellows after the air therein has been exhausted by suction as far as possible. At the same time there is atmospheric air pressure acting against ever portion of the outer surface of the bellows during the collapsing operation, and this is precisely the action to which the bellows is subjected in service, since in service the pressure is acting against the inner or outer walls of the bellows during the movement of the bellows, and not while the bellows is at rest. In many instances bellows are subjected to very low pressures, such, for example, as 1n packless valves, while in steam traps and certain types of thermostats, air motors and the like, the

pressure exerted is rarely above 20 pounds per square inch, and in manv oases does not exceed 15 pounds per square inch, which is the pressure exerted by the atmosphere during the testing operation described above. In Fig. 1 there is shown a plate 1, to the upper surface of which is secured a suction plate 2, which may be formed of rubber or 1 similar material. Both of the plates 1 and 2 are provided with aligned central openings which lead to, and connect with, a conduit 3 extending to a suitable air pump 4, while a vacuum gauge 5 is also connected to the conduit 3 for registering the degree of vacuum which is produced in the bellows. The air pump can be operated continuously while the operator will merely position a bellows: 6, having one closed end 7, in inverted position upon the plate 2, that is, withthe open end of the bellows against the plate. The air will be rapidly exhausted from the bellows, allowing the atmospheric pressure to collapse the bellows quickly and uniformly, and this will occur provided there is no leak in the bellows at any point. If there is a leak, then of course the bellows will not e01 lapse, or will collapse so slowly or incompletely that the operator can readily detect the difference and can throw the bellows out. As soon as the bellows is collapsed the valve 8, interposed in the conduit 3, may be closed,

thus interrupting the suction and allowing atmospheric air to flow into the bellows through a port 9, when the operator can readily remove the bellows from the plate and position the second bellows for collapsing. It has been found in raotice that this method of collapsing be lows provides a greater uniformity in the spacing and conformation of the various corrugations than is possible with other methods, while the action is extremely rapid. In addition to these advantages the bellows is automatically tested during, and by,'the collapsing operation.

Other modes of applying the principle of myinvention may be employed instead of the one explained, change being made as regards the means and the steps herein disclosed, proing a high vacuum therein to simultaneously test and collapse the same longitudinally to bring said corrugations into proximity to each other said last step effecting the permanent modification of the conformation of the several corrugations. I

4. In a method f making'flexible corruated metal walls, the steps which consist in orming substantially parallel s aced corrugations in a thin walled metal tu e, and then subjecting such tube to an evenly distributed endwise pressure sufliciently severe to permanently change the contour of said corrugations and collapse the same upon each other, while simultaneously testing the wall of said tube for leaks. Signed by me this 11 day of September,

ARNOLD 0. SCHARER.

vided those stated by any of the following claims or their equivalent be employed.

I therefore particularly point out and distinctly claim as my invention 1. In a method of making flexible corrugated metal walls, the steps which consist in forming substantially parallel spaced corrugations in a thin-walled metal tube, and then subjecting said tube to suction to cause longitudinal collapsing of the same and a simultaneous permanent modification of the conformation of the several corrugations.

2. In a method of making flexible corru-

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