US1550157A - Progressive system of brazing - Google Patents

Description

Aug. 18, 1925.

R. T. GILLETTE v PROGRESSIVE SYSTEM OF {BRAZING Filed Jan. 2, 1924 Robert T. 6i l'ette by Hus Attorney.

' required such frequent annealin Patented Aug. 18, 1925.

UNITED srnras PATENTLOFFICE.

ROBERT T. GILLETTE, OF SCHENEGTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A. CORPORATION OF NEW YORK.

PROGRESSIVE SYSTEM OF BRAZIN G.

Application filed January 2, 1924. Serial 110.68%,966.

To all whom it may concern: I

Be it known that I, ROBERT T. GILLETTE a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Progressive Systems of Brazing, of which the following is a specification.

My invention relates to the manufacture of seamed metal tubing and more particularly to the process of brazing the seam in tubes which taper and which are composed of a relatively high carbon steel.

Tapered steel tubes are useful in the construction of a large variety of articles among which may be mentioned golf sticks and fishing rods. In the case of articles like the latter which *arenorma'lly subjected only to abending stress, steel tubes with an open seam have been found quite satisfactory but where the article is subjected to severe tortional stresses, as is the case for'instance with golf sticks, such tubes have been found to be entirely inadequate. In order to obtain thedesired strength to withstand the tortional stresses met with, coupled with lightness, resort was had to seamless tapered steel tubes. Such tubes were made by swaging down straight seamless tubes but when a steel was used which could be tempered it that the cost of these operations in addition to the high initial cost of the seamless tubing becaine excessive. A golf club constructed in this manner is disclosed in Patent No. 976,267 to Arthur F. Knight.

In order to reduce the cost of construction it has been proposed to use a seamed tapered tube and copper-braze the seam in'the pres-' ence of hydrogen. When a furnace-is used which .is long enough to accommodate the entire tube and the temperature of the furnace is substantially uniform throughout. the length of the tube and sufliciently hi h to bring the large end of the tube' quicl y to the melting point of the copper brazing strip, the small end of the tube will be heated to a higher temperature than necessary or desirable and will usually befound to be in such a condition that it will not subsequently take a proper temper. This may be due to the reduction of the amount of car bon in the over-heated portion of the tube.

Unless great care is used, the small end of the tube-may reach such a temperature as to actually melt the steel.

An object of my invention therefore is to provide an improved process by which the aforesaid difficulties are overcome and by which seamed,tapering tubes of steel may be successfully and expeditiously brazed without injury to or change in the carbon of the steel composing the tubes. My invent1on comprises briefly a progressive s stem of brazlng in accordance with whic the tube to be brazed is moved through the hot zone of a relatively short hydrogen furnace at a speed in accordance with the melting of the brazing material.

My invention will be better understood by reference to the accompanying specificatl and drawing and its scope will be pointedout in the appended claims.

Figure 1 is a longitudinal section of an electric furnace suitable for carrying out my brazing process with a portion of a tube therein; Figure 2 is an enlarged view of the larger end of atube when ready for insertion in the furnace, and Fig. 3 is a View of the entire tapered tube.

Referring to Fig.1, a heating chamber is provided by a tube 1 of fused alumina, such as alundum, around which is a resistance heater 2 having terminals 3 and 4. The heater 2 may consist of a refractory metal such as molybdenum or tungsten or if do,

sired, iron wire or nichrome wire may be used. The tube 1 is held in a casing 6 and the space around the tube and heater is filled with a suitable refractory heat. insulating material 7 such mina,-'silica or the like. Secured to thecasing 6 and in line with the heating tube 1 is a cooling tube 10 hay-- ing a water jacket 11 surrounding it and connected by inlet and-outlet pipe 12 and 13 respectivelyto provide a continuous circulation of water therethrough. The outer end of tube 10 projects into chamber 15 which is closed except at the bottom where it dips beneath the surface of a bath of oil as powdered alu-' 16 contained in a vessel 17. An essential purpose and provision is made at 18 for "connecting the furnace with a source of supmay be connected to the same source of hy- I drogen. The gas admitted through this inlet or inlets fills the casing and by reason ofthe-perous nature of the alundumtube 1 eventually finds its way into the interior of the tube and escapes at its mouth together Withthe-gas which enters at 18.

"llultes such as that shown at 22 in Fig. 3 are firstformed up from sheet steel blanks tothe desired size and shape by rolling or by Suitable dies. edges of the seam a T-shaped steel strip isthen inserted with that portion corresponding to the cross member of the T lying against the inner wall of the tube and with that portion'correspending to the-shank ot' the *l lying-between the abutting edges of the tube. inthe manner illustrated by Fig. 2. The strip 23 may be formed up from sheet steel'of asmaller'gauge than that of' the tube but for the results should have the same chemical composition and elasticity as the steel of the-tube. At intervals the strip is provided with extensions forming lugs 24 which are bent over against the exterior of the tube after an"-a-rbor having the proper taper has been pushed into the tube to press the-strip'firnfly against the inner wall of the tube: A" strip 25 of copper or other suitable brazing material is then inserted in the tube and with the brazing strip 25 preferably lying in contactwiththe T-shaped strip 23 thetube is subjected to a temperature sufficient to melt' the brazing material while in an atmosphere of hydrogen or other reduc ing gas. ThebonStruction of the tube and the methodof making the same just described -a're disclosed in the co-pending applieation of William R. Emmet and Samuel 'llg'i horpe Serial No. 518,483,-filed Nov. 28,

For oam'ying out invention I employ.

even up to the point where it would cause Between the [abutting serious injury to the steel of the tube if the same portion of the tube is allowed to remain in the hot zone after coming up to the temperature-necessary tomelt the copper. It isnot essential, however, in the carrying out of my process that great care be exercised in maintaining the temperature of the furnace uniform or at any particular degree of heat. This feature is of practical importance since the difference between the temperature necessary to melt the brazing material and the temperature at which the tube will be injured is fairly small. Where the tube isnot tapered and is bodily placedin a furnace the temperature of which must be sufficient tov effect a braze and yetbe insuflicient to injure'the tube the furnace temmovement of the tube so that a higher f-ur-- nace temperature may be maintained, a more uniformly successful braze may be made and the operation much more speedily effected. Good iesults have been obtained with copper brazing when the hot zone ofthe furnace was maintained at a'temperature of from 1-200 C. to 1300 C. The operator is readily able to see into the open end of the furnace and to observe the various color changes of that portion of the tube in the hot zone. As the entering end of thetube is pushed forward .intothe hot zone it is soon raised to the temperature at which the copper at that portion in the presence of the reducinggas melts and flows into every part ofthe seam and unites with the steel of the tube and of the-strip 23 probably forming an alle-y'therewith. As rapidly as that portion of the tube in the hot zone is observed to reach the required temperatureto melt the copper, the tube is pushed on a little further, thus bringing a fresh portion of the tube up to a; brazing temperature andcarrying the previously brazed portion of the tube into a cooler section of the furnace-and eventuallyinto the. water jacketed part. By constantly observing that portion of the tube lying Within the hot zone the operator knows just how rapidly to advance the tube in order that each portion shall be raised to the required temperature andwithout subjecting any portion to such an overheating as would result in driving out the carbon of the steel. Should the copper uponmelting'tend to form globules or pools, a slight shaking or jarring f the tube will cause the pools of copper. to spread out in the desired manner. After passin through the hot portion of the furnace t 'e tube is pushed on into the water jacketed'tube 10 where it is cooled suflicientily to allow it to be ushed on to the point where it will: drop inte -the oil bath 9 hydrogen furnace having a hot zone mainteac er 16. Atter the tubes are removed from the oil bath the lugs 2t may be filed or ground ed to give the tubes a smooth, finished surface at the seam, and the tubes may then be tempered as desired Without in any Way aflecting the seam.

"What I claim as new and desire to secure by Letters-Patent of the United States, is,

1. The method of brazing the seam of a seamed metal tube having the brazing material along the seam by means of a furnace producing a temperature greater than that necessary to melt the brazing material and sufliciently great to injure the tube if applied indefinitely termined by the progressive melting of thestrip.

3. The method of brazing the seam of a tapering seamed steel tube having brazing material adjacent the seam by means of a tained at a tenggerature high enough to cause injury to consists in passing the tube longitudinally through the furnace ata variable rate such that each successive portion of the tube is which consists in passing the tube longitudinally through the furnace atv e steel of the tube Which,

heated only to ateinperature sucient to melt the brazing material.

. 4:. The method of brazing the seam of tapering seamed steel tube by means of a hydrogen furnace which consists in lacing a stripoit the brazing material along t e seam and-passing the tube and strip through the,

furnace at a variable rate such that each successive portion of the tube and strip are heated only to 'a temperature sufiicient to melt the strip.

5. The method of copper-brazing theseam of a tapering seamed steel. tube by means of a hydrogen furnace having a localized hot zone, which consists in placing a strip of at atemperature high enough to cause injury to the steel of the tube which consists in assing the tube longitudinally through the urnace at a varying rate dependingu pon the time required for the successive portions of the tube to reach the brazing temperature.

In "witness whereof 1 have hereunto set my hand this 31st day of December, 1923. ROBERT T. GILLETTE.

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