Патент USA US2412887код для вставки
Patented Dec. 17,1946 “2,412,887 " ' UNITED' STATES PATEN fr '_ osi-‘lcs 2.41am surnom Frederick P. Huston, Fanwood, and Lawton A. Burrows,v Woodbury. NJ., and Walter E. Law son, Wilmington, Del.; said Huston assignor to The International Nickel Company, Inc., New York, N. Y., a corporation of Delaware; said Burrows and said Lawson assignors to E. I. du VPont de Nemours & Company, Wilmington, Del., a corporation of Delaware Original application February 2, 1943, Serial No. 474,480. \ Divided and this appl’cation Decem bei' 19, 1944, -Serial No. 568,882. ïn @aliada `December 16,` 1942 l e claims. d(ci. ss-Lsl . lThe present invention relates to heat exchange is largely eliminated. invention will become apparent from the fol- i ‘ lowing detailed description of the invention taken change apparatus as boilers. Conventional staybolts for use in the assembly in conjunction with the drawing in which: of the nre sheets and wrapper sheets of boiler Fig. l shows a fragmentary sectional view of a lire boxes may be described as the screwed-` locomotive boiler nre box showing two embodi ments of staybolts produced according to the 10 present invention; the staybolt was screwed so that the ends ex ltended beyond the cuter faces of the fire sheet and wrapper sheet a distance `at least equal to two threads on the bolt. Flexible staybolts ex tended through the nre sheet in a similar man ner. _'I'hese extending ends were then upset so as `o form a spread rounded head. l Other objects and advantages of the present Wrapped sheets in the ilre boxes of such heat ex through ends-riveted type of construction. In fitting rigid staybolts in this ltype of construction the nre sheets and wrapper sheets were provided with aligned threaded openings through which 2 wrapper sheet due to notch eiiect in the threads- apparatus and, more particularly, to the stay bolts used for securing the fire sheets and Considerable . Fig. 2 is an enlarged fragmentary sectional view of one end of a staybolt provided with a charged explosive capsule, said staybolt being screwed into a 1tapped hole of a lire sheet; l Fig. 3 depicts a similar fragmentary sectional view of a reduced body staybolt screwed> into a. .tapped hole „in the ilre sheet, the bolt having a charge of explosive within a bore provided in .this end; and ’ diiliculty has been experienced with `this type of 20 Fig. e is a fragmentary sectional view showing construction due to leakage of steam and/or abolt similar to that of Fig. 3 in expanded con water between the male and female threads where dition following detonation of the explosive' the bolt passes through the‘sheet. This difficulty charge. " has been particularly 4acute on .the lire side of the Referring now more particularly to Fig. l, ref ñre box. . y . Difllculty was experienced not only in obtaining 25 erence character 2 represents the found-ation ring a tight fit between the staybolts and the ñre of a iire box having an outside nre box sheet or " ` sheets but also, particularly with staybolts of 4the rigid type. it had been found that numerous wrapper sheet ß and an inside iire box sheet or lire sheet 8. The lire sheet and wrapper sheet irá tlìe plane of the inner surface of the wrapper nated by reference character I2, isa rigid stay of are provided with aligned threaded holes` 8 in bolts broke in service. >It has been almost uni 30- which staybolts represented generally by th-e ref versal practice to construct nre boxes with wrap erence character S are litted. Two such staybolts per sheets of heavier gauge than the fire sheets, are illustrated in Fig. 1. One of‘these, desig and it was found that the staybolts which -brolre nated by the reference numeral l0, is a straight I in service almost always fractured substantially , body, rigid type of stay, whilefthe other, desig s ee . ‘ We have invented a staybolt and a method for expanding the ends thereof in the sheets or plates the reduced body type. ‘ Straight body rigid stays ordinarily are pro with threads throughout theiriength, The of heat exchange apparatus, boilers, or .the like, I vided reduced body rigid stays, on the’contraiyare which provides ñuid tight joints at any elevated 40 threaded only at the ends and the center region pressure normally encountered in such equip of the stay has a body of reduced diameter with ment, and we also have provided staybolts which respect to the threaded ends. Both types of are substantially free from breakage during use. rigid stays may be provided with a tell-tale hole, It is an object of the present invention to pro vide a staybolt >with means for insuring a fluid such as that illustrated‘at I4, or they may be 45 hollow .throughout their entire length as illus tight joint with a sheet through which it passes trated at it. » ' throughout the entire areas of adjacency between said staybolt and sheet.' _Another object of the present invention is to ` provide a means for expanding staybolts into 50 fluid-»tight engagement with the sheets with which they are usedby the use of explosive force. A further object of the present invention is the provision of staybolts in which concentration oi stresses in the plane of a lire sheet and/or 55 ,Moreoven in order to reduce the notch eñect of the threads, the threads may be machined off, as indicated at _22, .to provide a bolt having the lowest practical value of localized stress in the plane of the inner face of the Wrapper sheet and ñre sheet. The machining should extend only slightly under the root diameter of the vthreads so as not to reduce the net diameter or net larea of .the bolt appreciably. amasar> . 3 „ . 4> l » . The 'nre ysheet and wrapper sheet> ordinarily velocity explosive extending slightly beyond both will be made of rolled steel plates or sheets. The staybolts may likewise be made of steel but we prefer to make them of a nickel-copper alloy of ’the type sold commercially under the trade-mark charge 32 of the type of lead azide and mercury fulminate is adjacent to the base charge and is adapted to detonate said base charge at its maxi edges ofthe fire wall. A compressed primer . mum velocity. The ignition charge 33 is fired by “Monel" which contains approximately two parts of nickel to onepart of copper. `Great difliculty had been experienced in fitting means of the fuse 34.' ' _ " ‘ In carrying out our invention, various explo ' staybolts sufficiently tightly within the holes in sivesmay be used. It ispreferred, however, to prevented.' Attempts were made to .prevent leak age by extending thestays beyond the plate not less than two threads when installed and there the copending United States application, Serial _ the nre sheet and wrapper sheet that ‘leakage’ was 10 use the explosives described in greater detail in No. 426,150. ` ‘ » -. _ It is essential that the explosive be one of the after upsetting the end to provide a rounded head f classl designated as “high velocity explosives," in ' such as> that illustrated in Fig. 1 by reference 15 other Words, one that possesses a normal velocity . of detonation above 1000 meters per second when character 24. This expedient did not solve the dimculty since leakage still occurred ln- boilers shot under the usual conditions of determining velocity. \ The primary detonating compounds . having the staybolts headed in this manner. Moreover, in certain areas of the- fire box, the I may be employed, for example, mercury-fulmi rounded heads of the staybolts were rapidly cut 20 nate, lead azide, diazodinitrophenol. Preferably, y however, we- use explosives such at tetryl, nitro away by the flow of cinders until the bolt was lsubstantially flush with the exposed face of the e ñre sheet, thus destroying the sealing eiîect that the rounded heads were designed toproducïe. l We have discovered I'that completely ñuidf tight joints may be easily and inexpensively pro duced by expanding the ends of the 'staybolts through the use of explosive charges. For this purpose the end of the staybolt which is to be expanded is provided with a bore 26 adapted to receive an explosive charge. This bore should extend at least to the plane of the inner face of the ñre sheet or wrapper _sheetand preferably extends at least about '/s to 1% .inch beyond. In mannite, pentaerythritol tetranitrate, and the like, which detonate at high velocity and at the same time develop great' strength because of the 26 larger gas volumes. The amount of explosive may depend on the diameter of bolt, the charac- l ‘ 'teristics of the metal of the'bolt and other fac tors. It will be understood that the diameter of -the bore hole for containing the explosive should 30 lbe suinciently large to accommodate a charge of the proper amount. At the same time, the thick--ness of metal betweeny the center ~hole and the outer bolt wall must be enough to give.the nee ess‘ary strength when the metal has vbeen expand-v straight body staybolts the bore 26 may bea part 35 ‘ ed. An advantage of expanding. the staybolt in accordance with our invention over mechanical of the-tell-tale hole, but in reduced body stay bolts the bore 26 has a larger diameter than the expanding methods'lies in the uniformity of ex tell-tale hole. The bore 26 must not extend be yond the change of section since the net area pansion in all directions. ’ 'l . The following examples illustrate specific em ' bodiments of steybqlts Joined to metal wens of the cross section of the metal at the end should not be less than the net area in the reduced sec 4.o where the ends of said .bolts have been expanded tion. The staybolt -is screwed into the threaded holes in the rlre and/or wrapper sheet in the usual _manner and it may extend only- iiush with the exposed face as shown at 21 in Fig. 1, or it by means of explosive charges. ’ 1 ' _ Example No. 1 Y ' A threaded bolt of % inch diameter made of@ . may extend any-desired distance beyond, as illus the _nickel-copper alloy sold under the trade-mark vtrated in Figs. 2, 3 and 4. In Figs. 2 _and 3 the » play between the bolt S and the sheet 6 prior to expanding the end of the bolt has been exag-v “Monel” was screwed into the tapped hole of a gerated forpurposes of illustration. . Either> before or after the bolt is in position, an explosive charge 28 is placed inthe bore 26. ' '.Ehe explosive charge 28 may be loaded directly into the bore hole, if desired, as illustrated in Fig. 3. - nre sheet of 1/2 inch thickness until it extended slightly‘beyond the outside face of said sheet. A -bore hole of 0.235 inch diameter and of -% inch depth had been provided at the end of the bolt adjacent to the fire sheet and into this bore was inserted a cylindrical metal shell, adapted lto _ilt ' ' said bore and containing a compressed charge In such case it` may be desirable to insert a 55 „of 10 grains of pentaerythritol tetranitrate at `its disc'or closing- device at the base of the hole to keep the explosive from extending into the nar base, a primer charge of 2 grains of compressed lead azide adjacent to the base charge, and an ' row tell-tale hole. Since controlled compression l' ignition charge of a suitable mixture. The base of the charge is advantageous, it will ordinarily charge had been loaded under a pressure of about be preferred to precharge the explosive into a 60 5000 pounds per square inch and extended slightly cylindrical container adapted to f_it into the hole. beyond both faces of the wall. The charges were - ' This will obviate the hazards present in handling brought to explosion by means of a fuse. A close- ' and pressing _exposed explosive charges under fitting junction, impervious to high‘pressures, shop conditions. Various methods of bringing resulted from the expansion of thebolt'metal. . about the explosion ‘are suitable, such as the ap 65 Example No. 2 plication >of heat, percussion, the name from a fuse or other source, electrical methods, etc. In Fig. 2, an assembly is shown similar to that ' of Fig. 3, with the preferred method of loading Similarly, a threaded 7A; inch metal bolt was ‘ >screwed into another V2 inch steel plate. The and firing illustrated more'in detail. After the 70 bore hole in the bolt end wasof % inch depth and „ 0.235 inch in diameter. A cylindrical metal con bolt S is screwed into the ñre wall 6 so that the former extends slightly beyond the outer edge - tainer was inserted into thebore hole, said con tainer being loaded with a. 10 grain base charge of said wall, ametal shell 30 is inserted into the of tetryl, and suitable primer'and ignition combore hole 26 in the bolt and contains a com pressed base charge 28 Vof a high strength, high 75 positions. Again the base charge was such that 2,412,887 ' it extended slightly beyond both wall edges. 'I‘he _ explosion was brought about by fuse, and a tight joint resulted between the staybolt and the sur rounding metal. ‘ ’ . 6 Y Example No. 4 Heat exchange apparatus was constructed by means of explosive staybolts. A cylindrical cata- ' ' Example No. 3 lyst chamber was spaced within a cylindricalv steel case by means of steel staybolts 7g inch in Additional joints were made between staybolts and metal plates in which the tightness ofthe within the 1%; inch steel plate forming the steel diameter. The bolts were expanded exploslvely> case, and within the 5A; inch steel walls defining junctures were tested. A length of 4" diameter extra heavy steel pipe was first taken and closed 10 the catalyst chamber. The result was a heat exchange apparatus wherein the staybolt connec at -both ends by welding thereon pieces of % inch tions were pressure-tight both with respect to boiler plate. A tube was likewise welded onto the `heat exchange medium and the chemical the pipe-to allow the application ofhydraulic `liuid being treated in the catalyst chamber. The pressure and its measurement by a gauge. Two diiierent bolts made of the` above mentioned 15. connections between the bolts and the walls were effected by forming bore holes 0.235 inch in diam nickel-copper alloy were used with such a pres eter in each end ofthe bolt, and about 5/8 inch sure container, being screwed into opposite open in depth. The metal defining these-holes was ings in the two plates. Longitudinal holes were expanded into contact with the walls to be spaced drilled into the bolts, 0.235 inch in diameter to depths varying from 1% inch to 1/2 inch. Charges 20 apart, by means of .an explosive capsule loaded with a 10 grain base charge of tetryl and conven of pentaerythritol tetranitrate were used, varying tional primer and ignition compositions. Explo from 5.75 grains to 9.0 grains. In some cases the sion was brought about by means of a fuse to explosive charge was co-extensive with the thick cause the pressure-tight joints already described. ness of the plate, while in others it extended It is not essential in all cases that the stay slightly beyond the edge or just to said edge. It bolts and perforations be threaded as pressure vwas found, generally, that the tightest joints tight joints can be produced-by the process of resulted when the explosive charge overlapped the present invention between unthreaded bolts both edges of the plate slightly. In these cases and smooth walledl perforations or between stay it was found that the metal of the vstaybolt sur rounding the bore not only had expanded tightly 30 bolts and perforations'which are threaded’for only a portion of the thickness of thepllate. Nor « into contact with the wall of the perforation in is it essential that the base chargeof the ex the sheet but that it had even bulged slightly on plosive extend beyond both faces of the ñre or either side of the sheet, resulting in avery strong pressure-tight joint. Somewhat weaker joints ’were obtained when the explosive charge did not extend past the edge although these joints were also satisfactorily pressure-tight. Under condi tions where the charge extended slightly beyond both edges of the plate, tests indicated that no leaking occurred even under a pressure of 4800 , pounds per square inch. In no case did even a slight leak occur at a pressure less than 2200 pounds per square inch. This appears very strik wrapper sheet. Satisfactory fluid-tight joints are also obtained when the bolt terminates at the plane of the exposed face of the sheet,` as illus’ trated at 2l in Fig.- 1. This has the advantage of providing’ a smooth surface which is not cut away to any appreciable extent by the now of the cinders therealong. The bolt may also exl tend beyond the face of the'ñre sheet, as shown in Figs. 2, 3, and 4 and be upset after expansion to provide a, rounded head 26 as illustrated in staybolt I2 of Fig. 1. The present invention provides an extremely simple and rapid method of >ñtting staybolts 'so ` tightly in the boiler plates that the joints are fluid tight at pressures 1000% to more than ing and significant when it is realized that steam boilers ordinarily operate at pressures around about 225 pounds to about 250 pounds per square inch. Using a similar test and an explosive charge ` 2000% greater than the ordinary working steam of 10.5 grains of pentaerythritol tetranitrate, an pressure. In the United States the boilers ordi unthreaded nickel-copper alloy bolt was used. After the explosive charge had been detonated, _ narily operate at a pressure between the ranges of about 200 to> 300 lbs. per square inch, with an the joint was found to withstand a pressure cf average of about 225 to about 250 lbs. per square 3200 pounds per square inch without any leaki inch. The present >invention provides a high ness, which was the maximum pressure that safety factor even for boilers operating at very could be exerted on this. particular assembly. An additional test of an annealed 18-8 chro mium-nickel stainless steel bolt under similar conditions showed that leakiness occurred in no case at a pressure below 4600 pounds per square inch. , - ‘ v In the immediately foregoing examples, bolts much higher working pressures such as have been contemplated and to a certain extent used abroad with Working pressures in excess of 1000 lbs. per square inch. These joints are not only fluid-tight initially but they will remain fluid-tight in serv-~ ice.` As those skilled in the art are aware, stay bolts are exposed in service to severe stresses » have been used consisting of stainless steel and tending not only to loosen the joint between the Vthe nickel-copper alloy sold under the trade-mark “_Monel.” It will be understood that various other 65 staybolts and the boiler plates but even to fracture the bolt. Many boilers operate at temperatures metals having satisfactory mechanical, metallur up to 550° F. and even higher. These high tem» gical and chemical propertiesv for staybolts may peratures impose stresses on the staybolt and the be fitted bythe process embodying the present joint due to thermal expansions «of the metals of invention. Such metals as aluminum, nickel and copper; various nickel, aluminum and copper 70 the staybolts and boiler plates. Moreover, at alloys; steel and certain steel alloys; and many ` least once each month the locomotive must be washed out by emptying the hot water and re others may be applicable. It is preferable that ñlling with fresh water which sometimes is cold. a metal for expansion in accordance with our This invariably results in uneven -cooling of the invention have a potential elongation value of boiler producing very high stresses known in the at least 20%. A . 75 art as wash-out stresses. The staybolts and boll- . 2,412,887 8 contribution to the boiler art in greatly reducing ' I er plates are also under static stress due to the l such breakage and leakage. Thev ends of the bolts steam pressure. Moreover, _particularly in boil that are explosively expanded by the methodv em ers of locomotives and marine vessels, the stay-. bodying the present invention contact the."wa11s bolts also are exposed to dynamic stresses, me of the holes in the boiler sheets so tightly that chanical shocks, and vibrations resulting from the joints will remain fluid tight in service de- ' the movement of the boiler. The'movement of spite thermal stresses due to heating, cooling, the boiler may also impose sheer stresses from wash-outs, etc., and mechanical stresses resulting lwarping or wrenching oi.' the boiler assembly. from shocks, vibration, warping, and the like. . Thus, in locomotive boilers the weaving and warping of the locomotive frame is transmitted 10 The present application is a division of our co pending application Serial No. 474,480, ñled _Febto the boiler assembly and causes it also to weave and warp. The Association of American Rail ruary 2, `1943. ' , ì , l y . Although the invention has been described and illustrated in connection with certain-speciñc em roads and various engineering societies, including the American Society of Mechanical Engineers and the American-Society for Testing Materials, 15 bodiments, it will be appreciated that many modi iications maybe made therein without depart as a result of many' years of experience and re-' ‘ ing from the scope of the invention as deilnedin search, have developed codes and speciñcations, -deslgned to reduce staybolt breakage and leakage the following claims. to a minimum. See for example, the A. S. We claim: _ j Boiler Construction Code, 1940 edition, and the 20 - 1. A metallic staybolt having circular ends adapted for insertion into circular holes in re specifications lof _the .Association ofy American 'spective plates, whereby said plates are to. be Railroads, 1939 revision.` Some of-:tlie more im portant provisions relating to staybolts appearing ' joined and maintained at a predetermined dis ' tance apart, bores provided in each of said ends in these codes and specifications are as follows: 25A of sumcient depth to extend at least to the inner ,Physical and mechanical properties v . face of the respective plates, and a charge of high velocity explosive substantially filling at least one Tensile strength: 47,000 lbs. per sq. inch mini mum of said bores, said bores >being open- for escape of ` Yield point :` 60% oil the tensile strength as a. min- Y the products of explosion. f ' f 30. 2. A metallic staybolt having` circular ends Elongatlon in 8 inches: 28% minimum. adapted for insertion intocircular holes in re Reduction in area: 48% minimum. Maximum allowable stress on staybolts: 7,500 lbs. joined and maintained at a predetermined dis spective plates, whereby said` platesl are to« be tance apart, concentric bores provided in each of said ends of suillcient depth to extend atleast to the inner face of the respective plates, a. cap per sq.,inch and 8,000 lbs. per square inch', de pending upon the staybolt length, design and construction. . 35 ~ Permissible variation in size: The staybolt must be truly round within 0.01 inch and the diam . sule containing a charge of high velocity explosive substantially illling at 'least one of said bores, said bores being open for fescape of the products of mtcêre than 0.020 inch over the specified diam 40 explosion, and means for detonating said charge.> e r. `3. A metallic staybolt having circular threaded Tests: steybeits shan be tested et least every . ` ends adapted for insertion into circular threaded month and after every hydrostatic test. holes vin respective plates, whereby said plates are to be joined and maintained at a predetermined The hydrostaticy test shall be made at least every twelve months and it must `be carried out 45 distance apart, each of said ends being- provided with a concentric bore of suiiicient depth to ex at 25% greater pressure than the working steam pressure. In this'connectionit is signiñcant that ' tend at least to the inner face of the respective eter shall not be less than 0.005 inch over nor ‘ i plate, a capsule containing a charge of high ve- ~ the staybolts iitted in accordance with the pres locity explosive substantially filling each of said ent invention will> stand over pressures from 8 to 50 bores, said bores being open for escape oi the _ i6 times that specified for the hydrostatic test. Even vwith the precautions taken in these speci ilcations and codes breakageof the staybolt and leakage `between the staybolts and the boiler plates have occurred‘in normal operation of boil-- - ers. The' present invention makes an important 55 products of explosion, and means for detonating said charges. ~ - i FREDERICK P. HUSTON. _ LAWTON A.- BURROWS. WALTER E; LAWSON.