US3098662A

US3098662A - Metal joint or seal

Info

Publication number: US3098662A
Application number: US844998A
Authority: US
Inventors: Richard N Iversen
Original assignee: Weatherhead Co
Current assignee: Weatherhead Co
Priority date: 1959-10-07
Filing date: 1959-10-07
Publication date: 1963-07-23
Anticipated expiration: 1980-07-23

Description

July 23, 1963 R. N. IVERSEN 093, 2

METAL JOINT OR SEAL Filed Oct. 7, 1959 2 Sheets-Sheet 1 INVENTOR. R/CHARD M IVERSEN July 23, 1963 R. N. IVERSEN METAL JOINT OR SEAL 2 Sheets-Sheet 2 Filed Oct. 7, 1959 INVENTOR. iP/CHA RD IV- ll/EESE/V BY )P/CHEX MENE/VA/VJFAE/P/NG TON 1% MJM 761 A M r/V575 3,098,662 METAL JOINT R SEAL Richard N. lversen, Mayfield Heights, Ohio, assignor to The Weatherhead Company, Cleveland, ()hio, a corporation of Ohio Filed Oct. 7, 1959, Ser. No. 844,998 3 Claims. ((1285-48) This invention relates to multi-part steel fittings and to a method of making such fittings wherein one part of the fitting is formed of a transformed dimensionally stable steel and another part of the fitting is formed of a nontransformed dimensionally unstable steel which increases in size in response to a low temperature treatment and wherein the parts of the fitting are assembled with each other and thereafter subjected to such low temperature treatment.

The present invention also relates to multi-part steel fittings in which a body part of martensitic steel is provided with a bore surrounding a spool part of the fitting and wherein the spool part is formed of an austenitic steel and the assembled body and spool are subjected to a low temperature treatment resulting in the transformation of the spool and obtaining a fit between the spool and the body resulting from the dimensional increase in the transformed spool.

It is generally believed that martensite corresponds to an early stage of the transformation of austenite in passing through the critical range of the steel. It is also believed that martensite is a super saturated solution of C or Fe C in alpha iron. Martensite is most readily obtained by quenching small pieces of high carbon steel in cold water.

Austenite is generally considered as a solid solution of carbon or of the carbide Fe C in gamma iron. All steels above their critical range are made up of this solid solution. While austenite is present in all steels above their critical range, very little austenite is found in ordinary steels at room temperature even where steel is subjected to fast cooling.

Steels which are low in carbon and contain large percentages of chromium and nickel posses great resistance to corrosion and to scaling when exposed to high temperatures. Such steels are known as stainless steels. A common and widely used stainless steel is known as 18-8. This stainless steel is characterized in that it contains 18% chromium, 8% nickel and generally not over .15 carbon. When quenched from a high temperature, stainless steel remains untransformed, that is, austenitic, and the carbides are completely dissolved. In this form, namely, its austenitic form, stainless steels are highly resistant to corrosion and scaling. It has been found that after exposure to some 500 to 700 C., however, the stainless steel loses its valuable non-corrosion properties and fails through inter-granular corrosion. This is believed to be due to chromium-carbide precipitation, the carbides locating themselves at the grain boundaries. It is explained that such precipitation deprives the ion matrix of the chromium, an element imparting resistance to corrosion. The addition of such elements as tungsten, molybdenum and col-umbium resulting in the formation of carbides of these metals instead of chromium carbide is also suggested as a possible deterrent to inter-granular corrosion.

Other stainless steels currently in use include a composition where the carbon is in the range of .O8% to 012%, the chromium is present in the range of 16% to 17%, nickel 4% to 5% and molybdenum 2.5%3.25%. Such an alloy is also known as Am-350 which is made by the Armco Steel Corporation of Middletown, Ohio.

Another well-known stainless steel is identified as 17-7PH made by the Allegheny Ludlum Steel Corporation of Pittsburgh, Pennsylvania. The 17-7Ph stainless 3,98,65Z Patented July 23, 1963 steel is characterized by a carbon content of .09%, chromium in the range of 16%l7%, nickel 6.50% and aluminum .75 l.50%. It will be understood that in connection with the above examples the balance of percentages in each case is iron.

According to my invention stainless steels such as the steels above described are transformed from their austenitic state to a martensitic state by being subjected to a temperature of '1()=0 F. Such temperatures may be conveniently attained by the use of acetone and Dry Ice. It appears that the dimensional change attendant upon the transformation from austenitic to martensite is an increase of about .0025 inch per inch of material being treated. This increase in volume is along all axes of the material being subjected to the low temperature.

It is among the objects of my invention to provide a steel fitting of at least two parts and wherein one of the parts is formed of a martensitic steel and the other part is formed of an austenitic steel and wherein the two parts are assembled with each other and thereafter subjected to a low temperature treatment which is effective to trans form the austenite to martensite and change the dimensional relationship between the two parts.

It is a further object of my invention to provide a swivel fitting in accordance with the preceding object wherein a body part is provided with a bore and a spool is fitted within said bore and wherein the body part is made of a dimensionally stable martensitic steel and the spool is made of a non-stabilized austenitic steel and wherein the spool is fitted within the bore of the body and the parts in their assembled relation are subjected to a low temperature treatment effective to transform the spool from austenite to martensite and thereby obtain a fitting of the spool within the bore corresponding to the dimensional change accompanying the transformation.

It is among the objects of my invention to provide a swivel fitting comprising a body having a bore therein, a rotatable spool within said bore wherein the spool is provided with thin metallic portions bearing on the interior of the bore to provide a seal and wherein either the body or the spool is made of metal which is dimensionally stabilized by being in a martensitic condition and wherein the other part of the fitting, that is, either the body or the spool, is made of an alloy steel which has been transformed by being subjected to a temperature of about F. after the parts were assembled one within the other.

It is a further object of my invention to provide a fitting of two telescoped metal parts wherein one of the parts is stabilized and the other part is not stable and wherein the parts are fitted together and thereafter subjected to a temperature of about -l00 F. so as to transform the non-stable part and bring about a dimensional change in said part to provide an interference between the two parts.

It is a further object of my invention to provide a cylinder having a moving piston therein and wherein the piston is provided with a metal seal adapted to bear against the wall of the cylinder and wherein the cylinder is formed of a stabilized steel and the metal seal is formed of austenitic steel and wherein the metal seal is characterized by a dimensional change occasioned by lowering the temperature of the assembly of cylinder and piston to a temperature of about 100 F.

It is a further object of my invention to provide a fitting wherein the fitting includes one part made of a stabilized stainless steel and the other part is made of a nonstabilized stainless steel and wherein after assembly the parts are subjected to a low temperature of about 100 F. so as to bring about a dimensional change in the nonstable part of the coupling.

Further objects and advantages will appear from the following description and the appended drawings wherein:

FIG. 1 is an elevation in section of a swivel fitting suited for the handling of hydraulic fluids;

FIG. 2 is a sectional view of'a part of the fitting of MG.

1 showing the spool of the fitting during manufacture; FIG. 3 is a swivel fitting wherein separate metallic seals are employed between the spool andthe body of the fitting;

FIG. 4 is a showing with parts in section of a cylinder and piston assembly wherein the piston rodis sealed by a metallic seal and the piston is sealed Within the cylinder by a metallic seal wherein the seals are made according to my invention;

FIG. 5 is a sectional view of a modified form of a reciprocating shaft seal.

Referring to the drawings, a swivel fitting, as shown in FIG. 1, comprises a body part6 and a spool part indicated in its entirety as at 7. The body part '6 is provided with an inlet bore 8 leading through a passageway 9 into an axial bore .10 which receives the spool 111. The spool 11 is arranged to swivel within the bore of the body 6 and is provided with .a tubular portion 12 having a port 13 leading to the interior of the spool 7. The outer end of the spool is provided with a groove to receive a snap-ring 14 to retain the spool in its assembled position with the spool shoulder 15- bearing against the end face 16 of the body. The interior bore of the spool indicated as at 17 is closed by a plug 18 fitting in the interior threads of the bore 17. A bore 19 within the spool extends at right angles to the bore 17 and leads to the threaded outlet of the spool indicated at 20. It will be understood that tubular members or hose connections are received in the threaded portions 20 of the spool and 21 of the body and that the swivel will accommodate relative angular movement between the conduits connected at 20 and 21.

In making the swivel as shown in FIG. 1 stainless steel is preferably used for both of the parts, namely, the spool 7 and the body 6. Such parts are preferably annealed at l750 F. for an hour and water-quenched. The steel is then in an unstabilized or metastable condition and has at room temperature an austenitic structure which can be transformed into a martensitic structure upon cooling to a temperature of about 100 F. The body as a separate part is then cooled to lOO" F. for three hours. This transforms the austenitic steel to martensitic steel and brings about a dimensional increase throughout of about .0025 inch per inch of the material of which the body is made. The body in this transformed condition is stabilized dimensionally and will remain at such dimension throughout the normal range of use to which the fitting would be subjected. The dimensional change referred to here is independent of the co-efiicient of expansion characteristic of the steel.

The bore 10 of the interior of the body 6 is then finished by honing and the spool 7, which is made of austenitic stainless steel in the unstabilized or metastable condition, is ground and lapped to fit within the bore .10. Preferably all the parts are lapped together to establish an initial negative clearance of .0005 inch at the sealing surfaces.

The spool 7 is provided with integrally formed

lip seal portions

23 and 24. After the parts have been lapped and fited together as above described, the assembly is subjected to a low temperature of 100 F. for three hours. This transforms the spool and the attendant enlargement of the spool brings about a tighter interference fit between the lip seal portions on the spool and the body. Thereafter the assembly may be heat treated at about 850 F. for three hours for precipitation hardening and the fitting is ready for use.

During the manufacture of the fitting the interior of the bore 10 may be provided with a hard chrome micro-film electroplates thereon. Also, if desired, the

lip seal portions

23 and 24 may be silver-plated to improve the sealing and bearing relationship between the spool and the body.

From the above description it will be understood that the steel of the body is in a martensitic state at the time it is assembled with the spool and subjected to the low temperature treatment transforming the steel of the spool. Accordingly the same result may be obtained by using material other than stainless steel for the body as long as such steel is in a martensitic state.

In FIG. 2 the diameter indicated at 26 corresponds to the diameter of the bore 10 after the body 6 has been dimensionally stabilized. The clearance indicated at 27 indicates the clearance between the major portions of the spool exclusisve of the lip seal and the diameter 26 of the bore 10. This clearance is taken up on transformation of the spool to bring the major portions of the spool into bearing contact with bore 10. The included angle of the lip seal portion 24 with the bore is indicated at 28. The angle between the inner Wall of the lip seal and the axis of the spool is indicated at 28a. The changes in dimensions effected by the temperature changes have been exaggerated in the drawings for purposes of illustration.

A modification of the swivel fitting is illustrated in FIG. 3. In this form of my invention the body part 40 is provided with a bore 41 and a spool 4-2 is sealed within the bore of the body by means of sealing

rings

43 and 44. As in the first embodiment of the swivel fitting the spool 42 is provided with an axial bore 45 which is closed at one end by the plug 46. The body 40 of the fitting is provided with an inlet 47 and the spool is provided with an outlet 43. A shoulder 49 at one end of the body 40 provides an abutment for the righ-thand metallic seal 43. The lefthand metallic seal 44 is threaded into the end of the bore 41. The seal 43 has a metal lip 43a and the seal 44 is provided with a similar lip 44a to ride against the exterior of the spool 42 swiveled within the body 40. The outer end of the spool 42 is provided with a snap-ring 50 to hold the parts in their assembled relation. In this form of my invention both the body 40 and the spool 4-2 are preferably formed of a martensitic steel and the sealing members 43 and 44- are formed of a nonstabilized austenitic steel. The

seals

43 and 44 are lapped to provide a negative clearance of about .0005 inch. The parts after lapping are disassembled and washed and thereafter reassembled and the entire assembly subjected toa low temperature treatment of about l00 F. The spool 40 and the body 4-2 are not changed dimensionally by such low temperature treatment but the

seals

43 and 44 are changed dimensionally and provide an interference fit effectively sealing the swivel against the loss of hydraulic fluid.

In FIG. 4 a form of the invention is illustrated wherein metallic lip seals provide for sealing a piston Within a cylinder and also for sealing a piston rod against fluid pressure loss. The cylinder 61 is provided with a piston 62 and a piston rod 63 for reciprocating the piston in the cylinder. The piston 62 is provided a reduced diameter portion at each face thereof and such reduced diameter portion is threaded to receive the metallic

lip seal members

64 and 65. The cylinder head 66 is provided with an axial bore having an internal thread which receives the metallic seal member 67 surrounding the piston rod 63. In the cylinder and piston assemblage shown, the cylinder 61, the piston 62 and the cylinder head 66 are preferably made of a steel which has been stabilized as above described. The seals are made or" austenitic steel. The seal 67 is lapped onto the piston rod 63 and the seals 64 and 65' are similarly lapped with respect to the bore of the cylinder 61.

After the parts are lapped to provide a clearance such as above described, the entire assemblage is subjected to a low temperature treatment to bring about the dimensional changes and transform the steel of the lip seals from austenite to martensite. The changes in di mension attendant upon the transformation provide a desirable sealing fit between the metallic seals and the interior of the cylinder and the exterior of the piston rod.

A modified form of shaft seal is illustrated in FIG. wherein the end Wall 66a of a cylinder head is provided with an axially extending exteriorly threaded boss 66b. The piston 63a is arranged to reciprocate within the boss 66b. A metallic seal indicated in its enirety as at 121 is provided with a thin tapered sealing portion 123 arranged to bear against the piston rod 63a and a wedgeshaped sealing portion 122 arranged to bear against a tapered seat 660. The seat 66c is provided with a sloping entrance portion 124. A cap or gland nut 120 is interiorly threaded and drawn upon the threaded boss 66b. In this form of the invention the piston rod, the cylinder head 66a and the threaded cap 120 are preferably made of martensitic steel or steel which has been transferred to its martensitic state. The ring 121 is preferably in its austenitic state and when assembled with the parts as shown the assembly is treated at a low temperature of about -100 F. so as to transform the element 121 to its martensitic state and bring about the desirable results above described.

In all forms of the invention the device is suited for use at temperatures below 500 C. to 700 C. to insure the retention of the desirable non-corrosive qualities and to maintain the dimensional stability of the parts.

Although I have illustrated and described several forms of my invention in detail, it will be understood that numerous variations may be made therein without departing from the scope of the invention as defined in the following claims.

What is claimed is:

1. A metal swivel fitting comprising a body member having a longitudinal bore therethrough and a radial passage, a spool member rotatably mounted within said bore, a passage in said spool member adapted to communicate with said radial passage, one of said members having a cylindrical bearing and sealing surface adjacent the other member, said other member having a pair of axially spaced annular bearing portions, one on each side of said radial passage, said annular bearing portions being spaced from said cylindrical surface by a radial gap, a thin flexible annular sealing lip on said other member extending axially inward from each annular bearing portion to make sealing contact with said cylindrical surface, said one member having a martensitic structure, said annular bearing portions and said sealing lips having an austenitic structure adapted to be transformed into martensite in response to treatment at a temperaure of about l00 :F., to produce a dimensional change to increase the sealing contact pressure between said sealing lips and said cylindrical surface and to bring said annular bearing portions into bearing contact with said cylindrical surface.

2. A metal swivel fitting comprising a body member having a longitudinal bore therethrough and a radial passage, a spool member rotatably mounted within said bore, a passage in said spool member adapted to communicate with said radial passage, said body member having a cylindrical bearing and sealing surface along said bore, said spool member having a pair of axially spaced annular bearing surfaces on each side of said radial passage, said annular bearing surfaces being spaced from said cylindrical surface by a radial gap, a thin flexible annular sealing lip on said spool member extending axially inward from each annular bearing surface to make sealing contact with said cylindrical surface, said body member having a martensitic structure, said spool member having an austenitic structure adapted to be transformed into martensite in response to treatment at a temperature of about l00 F., to produce a dimensional change to increase the sealing contact pressure between said sealing lips and said cylindrical surface and to bring said annular bearing surfaces into bearing contact with said cylindrical surface.

3. A metal swivel fitting comprising a body member having a longitudinal bore therethrough and a radial passage, a spool member rotatably mounted within said bore, a passage in said spool member adapted to communicate with said radial passage, said spool member having a cylindrical bearing surface thereon within said bore, said body member having a pair of axially spaced annular bearing portions, one on each side of said radial passage, said annular bear-ing portions being spaced from said cylindrical surface by a radial gap, a thin flexible annular sealing lip on said body member integral with said annular bearing portions and extending axially inward from each annular bearing portion to make sealing contact with said cylindrical surface, said spool member having a martensitic structure, said annular bearing portions and said sealing lips having an austenitic structure adapted to be transformed into martensite in response to treatment at a temperature of about l00 F., to produce a dimensional change to increase the sealing contact pressure between said sealing lips and said cylindrical surface and to bring said annular bearing portions into bearing contact with said cylindrical surface.

References Cited in the file of this patent UNITED STATES PATENTS 608,852 Goss Aug. 9, 1898 615,509 Stevens Dec. 6, 1898 1,302,778 Drew-ry May 6, 1919 1,821,863 Wilson Sept. 1, 1931 2,506,558 Goller May 2, 1950 2,647,847 Black Aug. 4, 1953 2,789,928 Wallerius Apr. 23, 1957 FOREIGN PATENTS 706,342 Great Britain Mar. 31, 1954 OTHER REFERENCES Page 94 Steel, Nov. 6, 1944, Reclaims Undersize Pins. (Copy in Division 3.)

Claims

1. A METAL SWIVEL FITTING COMPRISING A BODY MEMBER HAVIN A LONGITUDINAL BORE THERETHROUGH AND A RADIAL PASSAGE, A SPOOL MEMBER ROTATABLY MOUNTED WITHIN SAID BORE, A PASSAGE IN SAID SPOOL MEMBER ADAPTED TO COMMUNICATE WITH SAID RADIAL PASSAGE, ONE OF SAID MEMBERS