US3690065A

US3690065A - Thermal actuator and method of making

Info

Publication number: US3690065A
Application number: US80229A
Authority: US
Inventors: Louis Bucalo
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-10-12
Filing date: 1970-10-12
Publication date: 1972-09-12
Anticipated expiration: 1989-09-12

Abstract

An article of manufacture formed of a plurality of layers of deposited metal with the layers being separated by interface layers which render the deposited metallic layers relatively movable under sheer stress to effect damping and decreased force deflection rate. In one preferred embodiment of the invention the article can take the form of a bellows defining a closed volume and having a core formed of thermal material having solid and liquid phases and affording substantially different displacements as a function of temperature.

Description

United States Patent Bucalo [451 Sept. 12, 1972 [54] THERMAL ACTUATOR AND METHOD OF MAKING [72] Inventor: Louis Bucalo, 135 Roberts St., Holbrook, NJ. 11741 [22] Filed: Oct. 12, 1970 [21] Appl. No.: 80,229

Related US. Application Data [63] Continuation of Ser. No. 854,024, Aug. 25, 1969, abandoned, which is a continuation of Ser. No. 584,037, Sept. 12,1966, abandoned, which is a continuation-in-part of Ser. No. 426,238, Jan. 18, 1965, abandoned.

[52] US. Cl. ..60/23, 29/ 156.4, 252/792, 252/794 [51] Int. Cl ..F0lk 25/02 [58] Field of Search ..60/23; 29/156.4

[56] References Cited UNITED STATES PATENTS 2,115,501 4/1938 Vemet ..60/23 2,128,274 8/1938 Vemet ..60/23 3,041,821 7/1962 Lindberg, Jr ..60/23 3 ,O99,222 7/1963 Poliseo ..60/23 3,183,672 5/1965 Morgan ..60/23 X 3,187,639 6/1965 Kelly et al ..204/9 X Primary ExaminerMartin P. Schwadron Assistant ExaminerA. M. Ostrager Attorney-John C. McGregor and James A. Eisenman [57] ABSTRACT An article of manufacture fonned of a plurality of layers of deposited metal with the layers being separated by interface layers which render the deposited metallic layers relatively movable under sheer stress to effect damping and decreased force deflection rate. In one preferred embodiment of the invention the article can take the form of a bellows defining a closed volume and having a core formed of thermal material having solid and liquid phases and affording substantially different displacements as a function of temperature.

5 Claims, 21 Drawing Figures .PATENTEBSEP 12 I972 SHEET1UF3 .690.065

FIG. 3

FIG. I

INVENTOR.

LOUIS BUCALO ATTORME'XJ PAIENTEDSEP 12 m2 SHEET 2 [1F 3 FIG.8

FIG.9

FIGJOA FEGJOC FIG. M

HGJO D R O T N E V N LOUIS BUCALO give.

y ATTORNEYS PATENTEDSEPIZ m2 3.690.065

SHEET 3 BF 3 FIGJZA INVENTOR. LOUIS BUCALO v ATTORNEYS THERMAL ACTUATOR AND METHOD OF MAKING This is a continuation of Ser. No. 854,024, filed Aug. 25, 1969, now abandoned, which was a continuation of Ser. No. 584,037 filed Sept. 1966 now abandoned, which was a continuation-in-part of Ser. No. 426,238, filed Jan. 18, 1965 now abandoned.

This invention relates to precision products formed of laminations of deposited metal, including variable shims, and various flexing members and as springs, bellows, diaphragms, couplings or the like, and to methods for the manufacture thereof.

Precision shims are used in the assembly of high precision equipment and instruments. The bearings of miniature gyroscopes, synchro motors and pumps, for example, must be set to extreme tolerances. One present day technique for precision shiming is based on the use of laminated shims built up of a plurality of layers, each of foil thickness and in which the foil layers can be successively peeled off to reduce the shim thickness by precise increments. As a practical matter, however, the thickness of each foil layer is large in relation to the precision demands of present day instrumentation. Moreover, it is difficult, particularly in the case of foil thicknesses of minimum size, to peel the foil without damaging the shim either by scarring, distorting, or the like. Moreover, it is often necessary to utilize supplemental adhesives between shim layers to insure the integrity of the product and such adhesive layers further reduce the precision and accuracy of the shim dimensions and the increments of change thereof.

In addition to their variable dimension characteristics, which render these products particularly suitable for use as precisely variable shims, they also exhibit unusual flexing characteristics deriving also from the unique laminates structure in which a controlled, releasable bond obtains between deposited 'metal layers. There is a notable decrease in force deflection rate for a given thickness of the laminated product. Also, an inherent damping capacity is achieved as a result of the degree of bonding between deposited layers. Depending on the bonding strength utilized, the laminated member can act as a single solid member until the shear stresses developed therein match the bonding strength between the layers, after which shearing occurs which provides unusual compliance with attendant increased damping, or hysteresis. These characteristics make such laminated members particularly useful for use as resilient devices, such as bellows, bourdon tubes, diaphragms, couplings, and other thin wall flexing members.

Accordingly, it is an object of the present invention to provide a laminated, deposited-metal structure in which the deposited metallic layers are united across interface layers which effect a precisely controlled bond therebetween capable of being released to effect either removal of one or more layers or controlled relative movement between layers so that either the dimensions of the member or its force deflection rate, or both, are precisely determined.

It is another object of the present invention to provide a product which is particularly useful as a precision variable shim in which increments of reduction of shim thickness can be made extremely small.

It is another object of the present invention to provide an improved precision shim which is capable of being reduced in dimension by precisely controlled increments of extremely small thickness without incurring distortion or other mechanical damage in the process of reducing the shim thickness.

Another object of the invention is to provide a shim capable of precision incremental reductions in thickness which is entirely metallic in its construction and free of adhesive layers and other materials which are relatively incapable of dimensional control.

Another object of the present invention is to provide a precision laminated product of deposited metal which can be economically fabricated in a wide range of shapes without sacrificing economy and accuracy.

Another object of the invention is to provide deposited metal, laminated products of various shapes in which long life under flexing conditions is obtained, and improved methods for making same.

Another object of the invention is to provide improved flexing products, such as bellows, bourdon tubes, diaphragms, couplings and the like, and improved methods for making same.

Another object of the invention is to provide a hermetic rotary seal capable of transmitting motion between two areas without any openings between the areas.

Still another object of the invention is to provide an actuator capable of yielding a positive displacement in response to temperature changes.

In accordance with the present invention a precision laminated product is fabricated by preparing a base or mandrel of metal, wax or other material and applying successive layers of metal by electrodeposition, catalytic deposition, vapor deposition or combination thereof or other techniques of metallic deposition. The deposited metal is applied in thin layers separated by interface layers of another metal or an oxide of metal until the desired total thickness is attained. The interface layer can be extremely thin, of the order of several molecules, to control the laminar bond, rendering it releasable or capable of shearing, as the case may be. In one preferred embodiment an extremely thin coating of a different metal such as copper is applied as the interface layer and a different metal such as nickel is deposited on the copper to a thickness of, say, 10,000 of an inch, after which copper and nickel are successively deposited until the desired end product thickness is achieved.

In use, if the product is to be a shim, successive layers are stripped off as desired to reduce the thickness by controlled increments. In such case the nickel layer can be removed in accordance with the invention by means, for example, of anodic treatment in a sulfuric acid solution or by chemical stripping such as Enthone N.P. Such stripping action completely removes the exposed nickel layer down to the first barrier layer of copper which is not affected by either the stripping chemical or the anodic treatment. The copper barrier is stripped by use, for example, of chromic acid bath to which the nickel layer beneath is impervious. For most purposes the copper layer is used as a boundary or shearing layer which is so thin or far beyond the tolerances of the shim that it is not reckoned in the dimensioning procedure. The next increment of thickness reduction is achieved, therefore, by removing the second nickel layer and thereafter repeating the processes until the shim is reduced to its desired thickness. Other combinations of metals and thickness for removal selectively are described below, together with various methods and apparatus useful in carrying out the invention.

In addition to their variable dimension characteristics, these products also exhibit unusual flexibility and are capable of flexing and absorbing shocks over an exceptionally long period of continuous cycling. There is a decrease in force deflection rate for a given thickness of material, and an inherent damping capacity deriving from energy dissipating between the layers. Improvements of a high order of magnitude in these characteristics for products such as bellows, bourdon tubes, diaphragms, couplings, or other thin-walled flexing members over those formed by conventional methods can be shown. To this end, in accordance with the invention, the flexing member, such as bellows, can be formed on a core mandrel which can, if desired, be removed by dissolving or melting or, in one embodiment of the invention the core is formed of suitable temperature responsive material such as wax and retained within a fully sealed bellows to act as an actuating medium, between its solid and liquid phases, for the bellows. Also, the bellows can be formed integrally and as part of one operation with various mounting parts, bosses, bearings or the like.

The above and other features and objects of the present invention will be apparent from the following specification describing preferred embodiments and taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view in cross section of a member formed in accordance with the present invention which is particularly useful as a shim;

FIG. 2 is a schematic view in cross section of a modified shim design;

FIG. 3 is a schematic view in cross section illustrating one method of fabricating a precision shim in a complex shape;

FIG. 4 is a view in transverse section of a circular shim;

FIG. 5 is a schematic view in vertical section illustrating a number of applications of shims formed in accordance with the present invention;

FIG. 6 is a schematic view illustrating another application of the invention;

FIG. 6A is a view in enlarged scale of a portion in vertical section of FIG. 6;

FIG. 7 is a diagrammatic view in distorted scale of a portion of the wall of a flexing member, such as a bellows, formed in accordance with the present invention;

FIG. 8 is a view in longitudinal section showing a flexible coupling element;

FIG. 9 is a view in longitudinal section showing a modified arrangement of a bellows or coupling member.

FIG. 10A is a side view ofa mandrel on which a flexible coupling or diaphragm can be formed;

FIG. 10B is a view in longitudinal section of a diaphragm formed on the mandrel of FIG. 9;

FIG. 10C is a view in longitudinal section illustrating a technique for achieving different thicknesses in different parts ofa flexible diaphragm;

FIG. 10D is a view in longitudinal section showing a finished coupling element;

FIG. 11 is a view in longitudinal section of a modified coupling element;

FIG. 12A is a view in longitudinal section of a temperature responsive device or thermal actuator formed in accordance with the present invention;

FIG. 12B is a view in transverse section of another form of thermal actuator;

FIG. 12C is a view in longitudinal section of a thermal actuator embodying a resistance heater;

FIG. 12D is a view in side elevation of another form of thermal actuator;

FIG. 13 is a view in longitudinal section of a rotary actuator in which the driving and driven ends are hermetically sealed one from the other; and

FIG. 14 is a view in longitudinal section of a hermetic seal member which can be used to convert a conventional toggle switch to a hermetically sealed switch.

Referring first to FIG. 1 of the drawing, the invention is illustrated as embodied in a laminated member particularly useful as a shim, which is shown in highly enlarged scale and which includes a base or mandrel 10, having formed thereon a plurality of layers of metal in sheet form. These metal layers are applied to the base 10 by means of metal deposition, such for example as electrodeposition, catalytic deposition, vapor deposition, vacuum deposition or combinations thereof. All of such methods are well known in the art and the specific details form no part of the present invention. In the illustrated arrangement

alternate layers

11, 12 and 13 are formed of one metal and the

other layers

14, 15 and 16 of another metal. Such metals can be selected from among copper, nickel, silver and gold. It will be understood that the two or more metals can be alternated until an initially desired thickness is built up. In the case of a shim the thickness is the desired characteristic; in the case of a flexing member the deflection is the desired characteristic.

The entire shim material in the form of deposited layers can either be removed from the base 10 or left bonded to the base which then becomes part of the finished product. In one preferred embodiment the layers ll, 12 and 13 represent interface layers or coatings and take the form of a thin flash of copper of the order of 10 millionths of an inch or several molecules thick and layers 14, 15 and 16 are formed of nickel deposited to a thickness of approximately 0.010 inches. The base 10 can be formed of brass or zincated aluminum.

When using electrodeposition as the deposition method, the base material, such as brass, is first plated by conventional strip plating techniques with a thin flash coating of the first material, such as copper, approximately 0.00001 (10 millionths) inch thick. A copper fluoroborate, copper cyanide, copper cyaniderochelle, copper pyrophosphate or copper sulfate baths are examples of the types of plating baths that can be used. Typical compositions of the baths are given in Electroplating Engineering Handbook, edited by Graham. The plated strip is then cut into the desired length and width smaller strips. The outside edge of the larger original strip may be wasted if the deposit on the corners is too large.

In the example just given, copper is used just as a coating or interface to form a barrier to the chemical stripping action between layers in the case of shims or as a shearable bonding layer in the case of flexible members. The actual thickness variation is achieved by chemically stripping the second thicker layer material. Copper need not, however, be limited to a barrier layer function. It also can be plated to different thicknesses and used to vary the total thickness of the shim or to vary the shear characteristics.

The basic construction can be cut, stamped or etched into any desired configuration. In use, the shim can be reduced in thickness by the user in steps which precisely correspond to the thickness of the

layers

14, and 16 by placing the shim in a chemical solution that attacks and removes the outside layer. Thus for example the layer 16 which is formed of nickel can be removed by immersion in stripping fluid such as an organic oxidizing agent of an ammoniacal base suitable for stripping nickel, such as Enthone N.P. The copper boundary layer 13 beneath the layer 16 is impervious to the strip chemical whose action is therefore arrested when the entire layer 16 has been dissolved. In this fashion the shim is reduced by a precisely predetermined amount which can be extremely small relative to conventional machine dimensions. To reduce the thickness a further predetermined amount, the flashing or boundary layer 13 is removed by a stripper such as CCL COONl-l, or chromic acid after which the next significant elimination layer 15 can be removed in the manner set forth above.

To minimize passivation of the layers and insure greater adhesion it will be understood that the deposition process may be conducted as a continuous operation in which the base strip is formed as a continuous or can be formed of brass. In this fashion the various layers can be selectively removed using a mixture of nitric aromatic acid salts and cyanides as disclosed in U.S. Pat. No. 3,242,090 and sold under the trade name McDermid AURO407 solution for removing the gold and a sulfuric acid base solution containing nitrates sold under the trade name McDermid CB solution to remove the silver. Large increments of reduction in dimension can be effected by removing the

layers

18 and 19 and small increments of reduction by removing the

layers

20 and 21 successively from the outside inward. Alternatively, the layers on the upper side of the base 17 and the layers on the bottom of the base 17 can be formed of the same combination of metals, such for example as copper and nickel and a masking technique such, for example, as adhesively bonded masking tape can be used to protect the surface which is not to be removed in cases in which like metals appear on opposite sides of the shim.

Many variations of base material and individual layers may be used in constructing the shim providing only that the different layers be capable of chemical dissolution without affecting the other layers. In the above example the copper layer can be removed in a solution of trichloroacetic acid neutralized with ammonium hydroxide (pI-l7-9) without affecting the nickel or brass base. A single nickel layer may be removed by anodic treatment in a sulfuric acid solution or by chemical stripping. The following series of examples show variations of basic shim materials and stripping chemicals which can be applied for the removal of the layers selectively and sequentially.

Example Base First Second Third Fourth First Second Third Fourth No. material layer layer layer layer stripper Stripper Stripper stripper 1 Brass C CC13COONH4 Enthone NP. CC13CCONI'IJ EntllonoNl. g C rbon steel Cu CCIz OONHt d0 CCI3COONII4.. DO. 3 Brass Cu CCl C0ONH4.. McDermid CCIQC()ONII4 McDermid Auro 407. Auro 407 Enthone NI .d0 Enthone NP. Do.

CCl COONH4.. EnthoneNI ..do Do.

CChCOONIIL. do CCISCOONIIL. Do.

. CChCOONHr ..do CCI3COONILL. Enthone NP.

EleetrolessN CClaCOONHt ..d0........... CCI3COONH4.. Do. Ag Enthone NP.... Chronic acid.. Entho11eNP Chromic acid. Cu Netex CB CChCOONHr Netex CB CClgOOONI'Iq.

) Ni Chromic acid... Enthone NIL... Chromie acid... Enthone NP.

zineated 12 Brass Cu Au N1 Ag CC13COON1I4 MtixDernig; Entlione NP Chremie acid.

uro

closed loop and passed successively through the variin the aft, to deposit the correct successive layers as part of one continuous operation. If less adhesion is' desired, it will be understood that passivation can be encouraged.

Referring to FIG. 2 there is illustrated a shim configuration in which the base sheet 17 has multiple shim layers of predetermined thickness applied to both sides thereof. On the upper side the layers 18 can be alternated with layers 19, both being of predetermined thickness of relatively large magnitude and the bottom layers can include

alternate layers

20 and 21 of relatively less thickness and which can be stripped off to afford very small increments of change in dimension. Four different metals can be used as, for example, the

layers

18 and 19 can be formed of copper and nickel, and the

layers

20 and 21 of gold and silver. The base 17 It is understood that the thickness of the various layers may be independently selected and that the method of deposition may be electrolytic, autocatalytic or vapor deposition. In most forms of the invention presented above the layers are adherently deposited to the base and to one another thus requiring chemical stripping means for thickness adjustment. In the cases where three or four different material layers are desired, one side of the base material can be masked by conventional plating techniques and the several layers deposited on the other side. When the layers are completed that side is masked and the masking removed from the base material in order to permit deposits of the layers on the other side.

If the base material is selected so as to provide poor adhesion of the first layer, as would be the case of nickel on stainless steel or nickel on a preplated base of nickel-tin, the deposited layers may be mechanically removed from the base as an integral sandwich. It is then possible for the base material to be used as a reuseable mandrel onto which the shim is repeatedly deposited and mechanically stripped.

A variation of this invention is made possible by changing the sequence of electrodeposition processes. Conventional laminated shims are manufactures by cementing thin sheets of metal together. When the thickness of the shim is to be varied for use, the layers are mechanically separated. Mechanically separable layers without adhesive are attainable in accordance with the present invention as follows:

On a stainless steel strip base a layer of say nickel 0.001 inches thick is deposited. While the strip is in solution a momentary reversal of the current is applied at about 10 ASP for 2 seconds. This reversal will cause nickel hydroxide to form on the strip. Immediately after the 2 seconds reversal the direct plating cycle is resumed to form another layer of nickel. This process of direct and periodic reverse plating is continued to form the desired number of layers of nickel. However, the imposition of the reverse cycle will render the bond strength of the various layers very low. As a result, the layers may be mechanically separated by peeling.

The production of these shims is not limited to strips. The base material can be cut, punched, folded, or the like to any desired shape such as round, rectangular or elliptical gasket shaped articles before deposition. In the cases where this shape precludes the use of a long strip of the base material, the shims could be individually racked and plated. In other cases the strip base can be masked with rubber cement compounds, air drying plastic, and/or plastic tapes to plate the strip in the desired shape. The excess base material can then be removed by mechanical or chemical means depending upon the material. If it is desired to hold the edges of the shim to close tolerances compared to the center dimension the pieces may be plated at low current densities like 2 ASP. For very close edge electroless nickel autocatalytic to center tolerances, an electroless nickel autocatalytic solution, also called Kanigen nickel solution, can be used.

The base material can also be in the form of a wire, thus comprising a core. The wire can be removed to produce a hollow tube shaped shim or bearing. If the first layer material is adherent to the wire, the wire can be removed by chemical etching, for instance aluminum wire can be removed with sodium hydroxide solution. If the first layer is non-adherent the wire can be mechanically removed.

Referring to FIG. 3 there is illustrated one technique for achieving predetermined shim shapes or geometries without necessitating cutting or stamping. To this end the base 22 has affixed to its surface boundary masks 23 and 24 which delineate precise shape of the shim to be formed. Particle deposition layers 24 and 25 are then applied to the base 22 in one of the various techniques described and the resulting shim is removed from the base and from the masking elements. Alternatively, the base 22 can remain attached to the shim structure and if sustained the base can take the form of a machine part such as a casing of a precision pump.

Referring to FIG. 4 there is illustrated a shim 25 which is of cylindrical or tubular form useful for example as a sleeve or bushing. Shim 25 can be formed in accordance with the invention by depositing the precisely dimensioned layers on a mandrel in the form of a metallic tube or wire which is thereafter removed by etching, dissolving or by mechanical extraction to leave the final cylindrical shape. Such cylindrical shim can have its inside diameter increased by removing inside layers or its outside diameter reduced by removing outside layers, all in accordance with the techniques described above.

Referring to FIG. 5 there is illustrated a piece of apparatus in which three different shim configurations are used. The apparatus takes the form of a gear pump in which the cover plate 26 includes attached edge shims 27 bonded directly thereto as part of the forming operation and in which the drive shaft 27 is received in a shim sleeve 28 corresponding to that of FIG. 4 and in which one of the gear elements is axially positioned by a flat, washer-shaped shim 29 which can be either stamped from a large sheet or firmed up by the technique of FIG. 3.

Referring to FIG. 6, the invention is illustrated as embodied in a spring 30 which is formed of

multiple layers

31 and 32 built up in accordance with the present invention and which can be successively removed to change the spring constant, which is a function of total thickness. It will be understood that appropriate selection of layer materials in the spring 30 can achieve a bimetallic temperature responsive spring, the response of which can be varied by removal of layers in predetermined amounts. It will also be understood that various electrical characteristics of a conductor or a member can be similarly controlable varied by removing predetermined quantities of material applied in layer form across boundary layers.

In addition to having a mechanical control over the springs constant by virtue of the ability to reduce the thickness by stripping layers, the spring also exhibits unusual characteristics in its behavior by virtue of the controlled bond between deposited metal layers. Because the bond is separable it has certain shear strength characteristics. For example, if the interface or bonding layer is formed of an extremely thin copper flash relative high shear bond strength, of the order of 20,000 psi is achieved when the deposited metallic layers are nickel of the order of 0.0002 inches. However, the current-reversing technique in the electrodepositing process, described previously, develops a nickel hydroxide coating on the previously deposited nickel. This results in a bond strength of the order of 1,000 psi between the nickel layers. This looser" bond decreases the stiffness or bonding stress by a substantial amount over the copper bond, which is itself a substantial improvement over conventional springs. Applied to bellows, as described below, a wide range of response characteristics can be achieved by these structures.

Referring to FIG. 7, there is illustrated a wall section 30 of a flexing element such as a bellows, coupling or other thin-walled member. The wall in constructed of N layers 31 of metal, such as nickel, each separated by a layer 32 of infinitesimal thickness of the order, for example, of a few molecules. The illustration is not in scale because the layers 32 are too thin for scale illustration. The layers 31 can be any metal or alloy capable of being deposited on a mandrel or form through electrodeposition, catalytic deposition, vapor deposition,

vacuum deposition, or a combination of these processes, all as described previously. Layers 32 constitute separation or interface layers of relatively low shear strength or bonding strength which can take the form of a thin deposition of a different metal such as copper or a passivated surface formed by an oxide coating.

In a specific example, the wall section 30 had a total thickness h of 0.005 inches and was formed of layers 31 of 0.0005 inches. Electrodeposited nickel cobalt was used for the layers 31, deposited in the following manner. The first layer 31 was deposited on an aluminum bellows mandrel which was later removed by dissolving. Following the first layer of electrodeposited nickel cobalt a low adherent layer was generated by reversing the plating current for one (1) second at 10 ASF. The following nickel cobalt layers 31 were similarly applied. It was found that the layers were so united in a relatively loose bond that the stiffness factor of the finished bellows approached l/N This was achieved in a single plating bath without removing the work from the bath.

In another example a thin flash layer of copper was used as the interface layer by deposition in a separate bath. The copper was deposited on a thickness of between one and five molecules. In this case after breaking the bond by flexing the bellows had a rigidity proportional to h /N each layer again acting separately in respect to bending. Had the product been constructed of a single layer of thickness h, the stiffness would be proportional to h. Thus in the above illustration, the flexibility in the multi-layer construction of 10 layers was increased by a factor 100, using layer thicknesses of 0.0005 inches.

The thin interface layers 32 can be formed in accordance with the invention by passivating each of the nickel surfaces after they have been deposited to the desired thickness. Passivating can be accomplished, in the case of nickel, by removing the product from the electrodepositing bath or other deposition apparatus and dipping it in a potassium dichromate solution. Thus the low bond strength layers can be achieved by chemical means in addition to the other techniques described. Broadly, passivity is a condition of a metal such that it assumes a potential more noble than its standard potential and there results an interface which brings about, in a laminated product of deposited metal layers, the useful flexing characteristics described herein.

It will be understood that members embodying the present invention can be formed in a wide range of shapes including, for example, a convoluted cylinder closed at its ends and adapted to expand and contract axially under the influence of pressure differentials. The same basic geometry with certain modifications can also be used for providing flexible couplings, and with further modifications, to provide hermetic seals. To some extent the unusual spring effects of the laminated members are utilized in each of these products.

Referring first to FIG. 8, the invention is illustrated as embodied in a flexible shaft coupling 33 including a central convoluted flexible section 34 and a pair of end fittings 35a and 35b. Shaft couplings typically require high torsional stiffness, but should also provide flexibility to compensate for shaft misalignment. To this end the walls of the convoluted'section 34 are formed of a series of layers of deposited metal separated by interface layers as shown in FIG. 7 to afford controlled shearing. The polar moment of inertia of the bellows or coupling 34 about its longitudinal axis or center line is not changed by virtue of the laminated construction. The torque carrying capacity of the coupling is therefore unchanged. For the same overall wall thickness, however, the stiffness is decreased by a factor of l/N about the horizontal and vertical axes perpendicular to the center line. The resulting product therefore has extremely long life and consumes relatively little energy even under serious misalignment conditions. The deposited metal layers can be formed into other shapes to provide other forms of flexible coupling.

In FIG. 9 there is shown a bellows or coupling in which the flexible portion is formed of a series of truncated cone sections 36 in the form of laminated members (FIG. 7) stacked together in inverse relationship and welded at their inside and outside diameters to form a unit.

Referring now to FIGS. 10A-10D, there are shown steps of one preferred method for fabricating bellows, flexible coupling or the like, particularly those-having their fittings formed integrally with the flexing portion. In FIG. 10A there is illustrated a mandrel or core portion 37 which can be formed of aluminum or plastic and on which a bellows having two different end configurations can be formed. The center of the core includes the usual convolutions 38, the lefthand end 39, a relatively narrow shaft receiving portion and the righthand end 40 an end fitting of larger diameter including a radial pin extension 41. In FIG. 10B there is shown deposited metal on the mandrel, preferably in multiple layers, as described.

If it is desired to form the ends or mounting portions of heavier material, the technique shown in FIG. 10C can be used in which, after the last layer of metal has been deposited to the desired thickness to achieve the requisite flexing characteristics in the convoluted portion, a barrier element such as a plastic tube 43 is fitted over the convoluted section and the assembly returned to the plating bath or other deposition apparatus to build up a thick relatively rigid metal layer on the exposed parts. The mandrel is then dissolved, as by the use of an acid bath and the unit is machined to provide the finished assembly of FIG. 10D. In this case, by removing both ends, the unit becomes particularly useful as a flexible coupling. With obvious modifications in the machining process it could be made into a closed bellows.

It will be understood that various other shapes can be similarly fabricated to form diaphragms, rupture disks and other complex geometries such, for example, as the coupling shown in FIG. 11 which includes, formed as one integral piece, a pair of mounting

end sections

44 and 45, a pair of

convoluted center sections

46 and 47 bridged by a straight cylindrical section 48. This configuration has been found to control undesired buckling by imparting rigidity to the center. In this arrangement separate, set-

screw clamping collars

44a and 45a are used to secure the two ends to the two shafts to be coupled.

The invention is illustrated at FIG. 12A as embodied in a thermal actuator in which the excursion and driving force can be augmented by the use of the encapsulated, temperature sensitive cores. The actuator 50 is formed by a deposition of metallic layers (as described previously) on a core 51 of thermal material such as thermal wax or low temperature metal having solid and liquid phases. In the deposition process, such as the electrodepositing bath, the mandrel is first formed into the desired core configuration, including convolutions, and maintained at a temperature which preserves the solid state. The shell 50 is electrically deposited in layers, using interface layers so there results an encapsulated, temperature sensitive assembly which is void free internally and which is capable of expanding or contracting axially as a function of the core temperature or phase or both. Most metals and waxes used for this purpose increase substantially in volume passing from their solid and liquid phases, although materials having the reverse behavior are commercially available. The change in phase takes place at a particular temperature over an extremely short period of time, so that the actuator will expand axially with great force and precision at the critical temperature. The fact that the shell is capable of expanding under very low deflection forces means that high efficiency is achieved. In a typical installation, the assembly is mounted in compression between a fixed reference support and say a valve actuator.

Various other forms and shapes of temperature actuator bellows or couplings can be provided as shown in FIG. 123 in which a flat diaphragm capsule is identified by the numeral 52, a bourdon tube by the numeral 53. Referring to FIG. 12C there is shown an assembly, identified by the numeral 54, including an internal heat exchanger in the form of an electrical resistance heater. The assembly includes a shell 55 filled with a thermal material such as wax 56, and having imbedded therein a resistance heater 57 adapted to be energized through suitable terminal connections 58 passing through the shell through suitable insulation beads 59. When the resistance element is energized the flexible diaphragm face will snap forward as the core material expands under changing phase. Thus from a heat or electrical input there is achieved a high force output displacement. This is brought about by the ex pansion of the incompressible wax 56 within the shell 55.

Referring to FIG. 13, the invention is illustrated as embodied in a hermetically sealed, rotary actuator assembly which provides a leak-tight seal across which rotary motion can be transmitted. The unit, identified generally by the numeral 60 is shown mounted in a pilot hole 61 in a panel or bulkhead 62. An internal rotor assembly 63, including a cylindrical base section 64 carrying an axially extended crank arm 65, is rotatably mounted in a bearing 66, preferably formed integrally with a multi-ply metal flexing and sealing member 67. The base or mounting end of the sealing member 67 includes a cylindrical portion 68 having an annular rib 69 on its outer surface, the bearing 66 on its inner surface and an elongated, convoluted sleeve portion 70 which envelops the crank arm 65. Carried at the free or remote end of the sleeve portion 70 is an actuating head 71 including an internal cylindrical bearing surface 72, which rotatably receives the tip a of the crank arm 65,- and an indented portion 73 which rests in an annular groove 65b to secure the sleeve to the end of the arm. The tip is coupled to a crank arm 74 on an output drive shaft 75 by means of a ball 76 received in a socket 77 in the free end of the crank arm.

The cylindrical portion, 68 fitted into the opening in the panel 62 with the rib 69 engaging a shoulder 61a, is soldered in place in a fluidtight seal. When the cylindrical drive member 64 is driven in rotary motion the crank arm 65 will rotate in the

bearings

66 and 72 on the sealing member and will at the same time turn the crank 74 and hence the output shaft 75 in a direct drive coupling. The flexible hermetic sealing member 67 will flex in vertical and horizontal planes but will not rotate. The relatively low deflection forces required to flex the convoluted section 70 permits the drive shaft to be rotated with minimum loss of energy and, because the unit is formed as one integral piece there are no sliding joints through which leakage can occur. The only seal required is the simple solder seal between the fixed bulkhead 62 and the cylindrical but non-moving base of the sealing member.

It will be understood that the laminated structure of the integral sealing member 67 is formed on a core in the manner described, with deposited metallic layers separated by low shear-strength interface layers, all as shown in FIG. 7. The material of which the first metallic layer is formed should be selected to provide a good working bearing, although if preferred, separate bearing sleeves can be interposed between the rotary and fixed parts.

Referring to FIG. 14 there is illustrated another embodiment of the invention by means of which conventional toggle switches can be hermetically sealed. A toggle switch 78 is mounted in an opening in a panel 79 by means of conventional clamping nuts 80 and 81 with the actuating finger or bat handle 82 of the switch projecting out of one end. Fitted over the exposed portion of the toggle switch handle 82 and the adjacent body portion is a sealing member in the form of a flexible multi-layered sleeve 83 including a central convoluted portion 84 and a cylindrical mounting end 85 adapted to be welded or soldered to the clamping nut 81 (and also, if desired, directly to the panel 79). A cantilevered sleeve extension 86 on its outer end receives the actuating handle 82. Thus the switch can be freely manipulated through a range of vertical or horizontal positions against the extremely small resistance of the flexing convolutions. As in the previous embodiments of the invention, the sealing member is entirely impervious to the passage of fluid because it has been formed in a single piece by the techniques described above.

Other arrangements and embodiments of the invention will suggest themselves to those skilled in the art. The invention should not therefore be regarded as limited except as defined by the following claims.

I claim:

1. An article of manufacture, comprising a deposited metallic bellows having a one-piece, fully closed, continuously uniform, deposited metallic wall defining a closed aperture-free volume free of sealed access openings and capable of expanding in at least one direction; and a solid encapsulated core of thermal material filling said volume as a void-free mass and onto which the bellows is deposited as an integral, aperture-free unitary structure, said core having solid and liquid phases affording substantially different displacements as a function of temperature and being permanently contained within the deposited wall, said expandable bellows thereby tracking precisely the expansion and contraction of the thermal core.

2. An article of manufacture as set forth in claim 1, including heat exchanger means within the core, and means external of the bellows for actuating the heat exchanger to change the phase of the core between liquid and solid.

3. An article of manufacture as set forth in claim 2, said heat exchanger comprising an electrical resistance heater.

4. An article of manufacture as set forth in claim 1, said bellows comprising a metallic member forming a plurality of discrete layers of deposited metal of predetermined thickness disposed in overlapping laminated relation, the respective metal layers being having solid and liquid phases affording different displacements as a function of temperature, said core having the shape of a bellows, and maintaining the core in its solid phase while depositing thereon one or more layers of metal to completely encapsulate the core in a fully closed, one-piece, continuous metal shell having the configuration of a bellows and free of access openings.

Claims

4. An article of manufacture as set forth in claim 1, said bellows comprising a metallic member forming a plurality of discrete layers of deposited metal of predetermined thickness disposed in overlapping laminated relation, the respective metal layers being separated respectively by interface layers selected from among deposited metal differing from that of the discrete layers or an oxide of a metal, thereby to afford a separable bond between the discrete layers, said member comprising a hollow unit having a wall portion capable of flexing in at least one direction and in which the separable bond between discrete layers of the wall portion yields under shear stress of predetermined value to effect damping.

5. In a method for making a metallic bellows, the steps of forming a solid, void-free core of a material having solid and liquid phases affording different displacements as a function of temperature, said core having the shape of a bellows, and maintaining the core in its solid phase while depositing thereon one or more layers of metal to completely encapsulate the core in a fully closed, one-piece, continuous metal shell having the configuration of a bellows and free of access openings.