US2930347A - Vacuum seal for evacuated systems - Google Patents

Description

March 29, 1960 J. J. BULLOFF 2,930,347

VACUUM SEAL FOR EVACUATED SYSTEMS Filed April 13, 1956 INVEN TOR.

JACK J. BULLOFF Attorneys Unite 1 States Patent F VACUUM SEAL FOR EVACUATED SYSTEMS Jack J. Bulloti, Dayton, Ohio, assignor to The Commonwealth Engineering Company of Ohio, Dayton, Ohio Application April 13, 1956, Serial No. 577,971

1 Claim. (Cl. 118-49) This invention relates to an apparatus and method for providing vacuum seals, and more particularly to a vacuum seal so constructed that materials can be moved into and out of a vacuum chamber or system without disturbing the sub-atmospheric pressure conditions under which the apparatus or systern is being operated.

The maintenance of satisfactory vacuum seals by conventional methods has been diflicult to accomplish, particularly the maintenance of substantially constant subatmospheric pressure conditions during the treatment of materials as a continuous process. Attempts to achieve this with gas-fed vacuum seals have not proved successful.

The present invention makes it possible to carry out a continuous process of treating materials under vacuum pressures, the material being preheated or electrically charged and processed while being maintained constantly under sub-atmospheric pressure conditions. The invention provides a method and apparatus whereby articles, substrates or the like, of indefinite length may be continuously introduced into a plating space, such as an air are illustrated which are suitable against ordinary atmospheric pressure conditions as the same is moved through an open-ended enclosure in Which the article is treated, as for example, in carrying out such treatment as carbonizing, siliconizing, bondizing, aluminizing, anodizing, chromiumizing, manganizing and the like.

These and other objects and advantages of the invention will be apparent to those skilled in the ,art from the following description taken in conjunction with the accompanying drawings, wherein apparatus embodiments for practicing the invention.

In the drawings:

Figure 1 depicts in cross section, a suitable apparatus for vacuum sealing an enclosure in accordance with this invention;

'Figure 2 is a similar view in vertical section illustrating. a modification of the vacuum sealed apparatus for carrying out gaseous plating;

evacuated enclosure, and metal plated and continuously withdrawn therefrom while the vacuum seal is retained.

The invention provides a suitable apparatus and method whereby liquid phase metal spraying may be carried out under sub-atmospheric pressure conditions, as for example, produced by such processes as vacuum sputtering, gas sputtering, flame spraying, electrostatic spraying and the like, and wherein it is requisite to carry out the coating treatment under vacuum or sub-atmospheric pressure conditions.

It is another object of the invention to provide an apparatus for operating under sub-atmospheric pressure conditions and which permits the movement of materials to be treated in and out of the apparatus while subjected to reduced pressure conditions as, for example,

when gas plating a coating film of metal onto the sur-' face of such materials. 7

Another object of the invention is to provide an apparatus for applying a metal coating by gas plating which permits continuous operation under either high vacuum or low vacuum, or gas-filled atmospheric conditions.

Another object of the invention is to provide an ap paratus and method which is especially useful for effecting the continuous plating of filaments, fibers, sheets or conveyed solids, e.g., by the low temperature decomposition of metal-bearing vapors or gases on heated surfaces, and such as effected by the continuous operation of the so-called gas plating process.

Another object of the invention is to provide a method and system of plating heated surfaces wherein the decomposition of the metal bearing vapor or gas is aided by the presence of reducing agents which promote metal deposition by chemical reaction processes, and such as produced by continuous operation of vapor plating? processes. U

Still another object of the invention is to provide a method of vacuum sealing a continuous length article Figure 3 is a sectional view of 'a combination heating and gas plating chamber for carrying out gas plating of long continuous length material as a continuous process under sub-atmospheric pressure conditions;

Figure 4 is a sectional view illustrating a suitable apparatus for treating separate articles under vacuum or sub-atmospheric pressure conditions as a continuous process;

Figure 5 is a sectional view taken on the line 5-5 of Figure 4, is and looking in the direction of the arrows.

Referring to the drawings, and particularly to Figure I, there is illustrated a vacuum chamber 10 having inlet and outlet openings 11 and 12 respectively, through which material of indefinite length, such as shown at 14, is adapted to be moved while thus treated.

To provide for vacuum sealing of the chamber 10,

' a vacuum pump 16 is connected through a manifold or conduit 17 to inlet line 18, as illustrated in Figure 1. Similarly, a vacuum pump 19 communicates through a conduit 20 with outlet line 21 of the chamber 10. Vacuumpressure conditions in chamber 10 are predetermined by operation of the vacuum pump 23 which is connected through a conduit 24 and opening 25 to the chamber 10'.

The continuous length material 14 or substrate work to be treated in the chamber 10 is moved along continuously therethrough without loss of the vacuum, the same being maintained by continuous operation of the vacuum pumps 16 and 19. Suction created at the inlet 11 and outlet 12 of chamber 10is controlled by operation ,of the pumps whereby the pressure within the chamber 10 remains substantially constant. Where the substrate or material 14 receives treatment only in the chamber.

10 asin the case of vacuum evaporating, vacuum metal;

lizing, molecular distillation, molecular distillation deposition, vacuum sputtering, deposition sputtering, gas sputtering, and protective flame spraying or the like, the embodiment illustrated in Figure 2 is utilized. 7 I

In Figure 2 the apparatus illustrated comprises a bell jar enclosure 30, the peripheral edges 31 of which rest on a grommet or sealing member "32 made of plastic, sponge rubber, or the like, which in turnis suitably. mountedion a supporting base 33. An inlet opening'35 and outlet opening 36 is. arranged in. the base 33 to which is connected'respectively the manifolds or conduits 37 and 38. Material to be treated "such as illustrated at 40 is threadedthrough the inlet conduit 37 and over an arcuate assembly of guide pulleys 42, 43, 44, as shown guide rollers are substituted for the guide pulleys or wheels.

Treating agents, such as a heat decomposable metal bearing gas, are admitted to the bell jar chamber through an inlet conduit means 52. To maintain vacuum or subatmospheric pressure conditions continuously in the bell jar chamber 30 while moving the material 40 in and out of the chamber, a conduit 54 is connected to the inlet conduit 37, conduit 54 being in communication with a vacuum pump. Similarly, the outlet conduit 38 is connected through conduit 55 to a vacuum pump whereby the inlet and outlet openings are maintained under sub-atmospheric pressure conditions similarly as the atmosphere in the bell jar. In this manner, material to be treated under vacuum pressure conditions such as filaments, sheet, or continuous length articles, may be passed into and out of the vacuum sealed bell jar 30 and subjected to treatment, e.g., gas plating to deposit metal on the surface of the material.

In Figure 3 a modified apparatus is illustrated for carrying out preheating and vacuum treating of continuous'length material. In this illustration a vacuum treating chamber 60 is illustrated, having an inlet conduit connection as at 61, and an outlet conduit or manifold pipe communicating therewith, as at 62. For maintaining sub-atmospheric pressure conditions within the chamber 60, conduit connections 63 and 64 are provided which are in communication with a vacuum pump, not shown. The connection through conduit 63 provides a vacuum seal for the inlet conduit 61 and conduit 64 which is in communication with the outlet. conduit 62 and provides for vacuum sealing the outlet from chamber 60 to thus maintain sub-atmospheric pressure. conditions in the chamber.

An inlet opening 65 and outlet 66 is provided for circulating treating gas, such as heat-decomposable gaseous metal compounds as when carrying out gas plating, through chamber 69. Connected through a common inlet conduit or manifold pipe 61 is a heating chamber 67, the pipe 61 being connected to the outlet 68, of chamber 67. Continuous length material, such as shown at 69, is adapted to be drawn through both the heating chamber 67 and the gaseous plating chamber 60.

In chamber 67 the material 69 is preheated by heat ing elements 70 arranged in the chamber, as illustrated in Figure 3. Heating elements 70 are in theform ofelongated plates preferably heated by electrical resistance, the plates being disposed at opposite sides of the continuous length material 68; The material is thus pretreated under vacuum conditions as it is drawn through the heating chamber 67 before it is advanced into. the plating chamber 60; Vacuum conditions are maintainedin the heating chamber 67 by means of a vacuum pump which, through conduit 72, is operatively connected to conduit 73' forming the inlet pipe to the heating chamber. Vacu: um sealing of the outlet 68 is provided by a vacuum pump connected to conduit 61 through pipe 63.

The vacuum sealed apparatus illustrated in Figures 1, 2 and 3 is adapted for use in evacuated systems wherein long continuous length material is to be treatedwhile maintained under sub-atmospheric pressure conditions. Such materials may comprise a wire, string, fiber, filament, roving, thread, ribbon, tape, strip cloth, fabric, foil and the like.

In Figure 4 there is illustratinga suitable apparatus for carrying out a multi-stagevacuum pressure treatment on aplurality of individual articles or bodies, in a continuous operation, e.g., while being. conveyedjto a loading or storage station. In the assemblyline arrangement shown in Figure 4, articles, substrates or the.like, such as indicated at 80, 81, 82, are supported andjconveyed along in the, direction indicated by the arrows. Endlessbelts 84, 85, 86 which are. positioned end-to-end support and convey the articles therealong through the treatzones or chambers A and B. These belts may be made of rubber, plastic, silicone rubber or the like material which is flexible and pressure scalable. The endless belts are actuated by the driven rolls or wheels 88. The driven rolls 88 rotate in the same direction to cause the several belts to move in unison and convey the articles into and through the enclosures A and B.

For sealing ofi of chambers A and B horizontally disposed revolving doors or wheel closure members generally designated, 91., 92, 93 are provided. Each of the revolving doors or wheel closure members are similarly constructed and operated, being preferably made up of six equal size flaps 94 hung at equal angular positions with respect to each other on a common hub or axis 96. The fiaps are revolvable together in a kind of cylindrical vestibule as formed by the arcuate wall member 97. One pair of flaps are arranged to fill the opening so that air is excluded.

Disposed on the outer ends of the flaps 94 are sealing pads 98 which are adapted to contact the surface of the belt, as illustrated in Figure 4, and seal the chamber off from the atmosphere. The arcuate guide sealing wall member 97 is adapted to receive the pads 98, as the closure door or wheels rotate under the pushing force exerted by the article moved thereagainst by the conveyor belt.

For maintaining sub-atmospheric pressure conditions within the zones or chambers A and B, disposed between the revolving closure members 91, 92, 93 conduit means 102, 103, 104 and 165 are provided. Each of these conduits are connected to a vacuum pump, not shown, and the low pressure conditions are maintained in chambers A and B by operation of the vacuum pumps. As will be observed, articles which are transported on the endless belts 84, 85, 86 pass beneath the revolvable closure door members 91, 92, 93 and through the air excluded chambers where the article is treated while retained under sub-atmospheric pressure conditions. Side wall sealing of revolvable door closure members is provided by extension of the same laterally so that they contact theopposite end walls 106 and 507, as illustrated in Figure 5. Similarly sealing rolls 169 are provided for closing the space between the endless belt and the bottom wall portion 110 of the enclosure. Inlet conduits 112 and 113 are also provided in the upper wall 115 of the enclosure for permitting the introduction of treating gases as desired to chambers A and B. Suitable valve means, not shown, may be utilized as desired to control the passage of gases or fluids into and out of the vacuum sealed enclosures during treatment of the materials and as the same is moved through the enclosure.

As will be observed, the articles to be treated may be subjected to one or more treatments while maintained under sub-atmospheric pressure conditions, and the operation may be-carriedout as a continuous one without theloss of vacuum. Further, by driving the endless belts at different speeds, the time allotted for an article to remain ineach vacuum sealed chamber may be predetermined as may be required for diilerent articles or treatments.

In the use of the apparatus as illustrated in the several figures, difierent atmospheres manifestly may be employed, such as steam, nitrogen, argon, helium, and the like; Further, the atmosphere within the enclosure may be readily controlled to provide the concentration of the elements desired. The material to be treated in each instance is moved through the low pressure chamber while the same is being treated and while retained under the atmospheric pressure conditions required during the treatment. Maintenance of the vacuum seal by means of the=vaeuum pumps maybe effected using independently operated pumps connected to the inlet and outlet or one or more common operated vacuum pumps may be employed. The vacuum seals thus permit the entrance and exit. of the material or articles to be treated without interfering with the vacuum conditions. The invention accordingly provides for treating material continuously as the same is moved along under low pressure or vacuum conditions and without the necessity of opening and closing inlet and outlet openings.

Where the material to be treated under sub-atmospheric pressure conditions is required to be preheated, then the apparatus as illustrated in Figure 3 is utilized. Further, where the articles are to be given one or more duplicate treatments as in the application of coatings or the like, or where successive and diflerent treatments are to be carried out under vacuum conditions, then the apparatus illustrated in Figure 4 may be utilized. The latter apparatus is particularly useful where articles rather than continuous length sheets or filaments are to be treated under sub-atmospheric pressure conditions.

The invention illustrated and described thus provides an apparatus and method whereby materials can be continuously treated under sub-atmospheric pressure conditions without closing the chamber off to the passage of the material through the low pressure chamber. Unlike gas fed vacuum seals, thus low pressure conditions can be maintained in the enclosure and unlike venturi actuated vacuum seals a low pressure condition can be maintained in the chamber without the use of a large expenditure of energy to maintain the seal.

It will be understood that while the method and apparatus disclosed and described herein illustrate a preferred form of the invention, modifications can be made by those skilled in the art without departing from the spirit and scope of the invention, andthat all of the modifications that fall within the scope'of the appended claim are intended to be included herein.

What is claimed is:

Apparatus for gas plating metal on the surface of preclosure into a plurality of gas plating compartments, said revolving doors comprising a plurality of angularly spaced closure members which are secured 'at their inner end to a common axle, each of said closure members comprising a flexible flap disposed on the outer end thereof which is adapted to contact the surface of the endless belt conveyor means and maintain the compartments closed against flow of gas from one compartment to another, inlet and outlet openings for each of said gas plating compartments, and means for introducing gaseous metal bearing compounds which are thermally decomposable into each of said compartments for gas plating said articles to provide the same with a plurality of metal coatings as the articles are'being conveyed through said gas plating enclosure.

References Cited in the file of this patent UNITED STATES PATENTS 2,382,432 McManus et al. Aug. 14, 1945 2,384,500 Stoll Sept. 11, 1945 2,580,976 Toulmin Ian. 1, 1952 2,599,978 Davis et al June 10, 1952 2,638,423 Davis et al. May 12, 1953

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