US2577644A

US2577644A - Apparatus for anodically treating internal surfaces

Info

Publication number: US2577644A
Application number: US93517A
Authority: US
Inventors: Kenneth M Bartlett
Original assignee: Thompson Products Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1943-04-09
Filing date: 1949-05-07
Publication date: 1951-12-04
Anticipated expiration: 1968-12-04
Also published as: GB611610A

Description

Dec. 4, 1951 BARTLETT 2,577,644

1 APPARATUS FOR ANODICALLY TREATING INTERNAL SURFACES Original Filed April 9, 1943 VE/7 ffiq 42/7/72 ffx/ffla ff/eii.

Patented Dec. 4, 1951 1;

APPARATUS FOR AN ODICALLY TREATING INTERNAL SURFACES Kenneth M. Bartlett, Cleveland, Ohio, assignor to Thompson Products, Inc., a corporation of Ohio Original application April 9,' 1943, Serial No. 482,379. Divided and this'application May 7, 1949, Serial N0. 93,517

1 Claim. (Cl. 204222,)

This is a division of application Serial No. 482,379 filed April 9, 1943, now abandoned.

This invention relates to an apparatus for anodically treating internal surfaces, and more particularly to the anodic descaling of internal surfaces of a hollow metalvalve.

In the manufacture of hollow metalvalves, either by forging or casting methods, it has generally been found necessary to clean the internal surfaces of the head cavity of the valve in order to free such surfaces from scale resulting from the forging and heat treatment and to provide surfaces having a high rate of heat transfer between the walls of the head of the valve and the coolant with which the valve may be partially filled. Various methods of cleaning the internal surfaces of the head cavity of hollow valves have been devised, such as sand blasting, or other mechanical methods, but these have proved rather unsatisfactory.

I have now found that it is possible by the use of an anodic electrolytic method to descale the internal surfaces of hollow metal valves, and particularly the internal surfaces of the head cavity. In accordance with the present invention, a collapsible cathode is inserted into the hollow metal valve to provide conducting means extending adjacent to and in general conformity with the interior walls of the head cavity. Preferably, a hollow or tubular member is employed for supporting the collapsible cathode within the head cavity, in orderthat the electrolyte used may be introduced into the interior of the valve through such hollow or tubular member. The valve-is then made the anode and an electrical current passed through the electrolyte from the anode to the cathode of sufficient current density and for a sufficient' length of time to effect a complete descaling of the walls of the head cavity of the valve. There is thus provided a simple yet effective method for descaling the interior wall surfaces of a hollow metal valve, without the necessity of employing mechanical cleaning or descaling means.

It is a further important object of this invention to provide apparatus for use in the anodic descaling of internal surfaces of a hollow metal object, such as a hollow metal valve, which apparatus includes a tubular member for the introduction of the electrolyte into the interior of the valve and a collapsible cathode carried by the end of said tubular member and adapted, when extended, to lie adjacent to the walls of the valve head and in general conformity therewith. 1

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawings.

- On the drawings:

Figure 1 is an elevational view, partly broken away and in section, of a form of apparatus adapted for carrying out the method of my invention;

. Figure 2 is an enlarged, fragmentary, sectional view of the valve itself and the attachments therefor, with parts broken away and in section and with parts in elevation; and

Figure 3 is an enlarged, fragmentary detail view of the collapsible cathode used in the apparatus of my invention. i

The reference numeral [0 indicates generally a supporting stand, such as a ring stand, having a base ll. and an upright rod l2, on which are adjustably mounted a plurality of clamping members. One of said clamping members, in-

dicated by the reference numeral I3, is adapted to support the hollow metal valve [4 in substantially vertical position with the head end [5 at the bottom and the open stem end It at the top. Saidclamping member I3 is adjustable along the rod I2 by means of a thumbscrew I1. The supporting end of the clamping member l3 is an integral ring l8 having an annular lining IQ of rubber or other insulating material. The stem portion is adapted to be inserted into the opening provided by said lining l9 and to be frictionally held therein.

Another clamping member 20 serves to support a reservoir 2| for containing an electrolyte 22. Said reservoir 2| is suitably provided with a stop cock 23 for controlling the flow of electrolyte through a flexible hose 24 into a tubular member 25 that extends into said hollow valve I4. The tubular member 25, which may be formed of stainless steel, copper or other electrical conduc tive materials, is supported above the valve M by means of a clamping member 26, from which it is insulated by an insulating sleeve 21. An apertured spacer 28, positioned in the stem end I6 of said valve l4, permits the tubular member 25 to be inserted therethrough and serves to center and space said tubular member from the walls of the valve. A similar, apertured spacer 29 is adapted tobe positioned within said hollow valve l4 near the end of the stem cavity 30 thereof. Said

spacers

28 and 29 are provided with fluid flow passages 3| and 32, respectively, and also with apertures 33V-and 34 for a purpose that will later appear.

l6 of said valve 4' The tubular member 25 is provided with a stopoif coating 35 for the portion of its length that extends within said hollow valve Hi. The purpose of this stop-off coating is to prevent contact between the external surface of said tubular member 25 and the electrolyte with which the hollow valve I4 is filled during the anodic descaling process. In the particular process about to be described, wherein the walls of the head cavity only are to be anodically treated, it would be undesirable to have the external portions of the tubular member 25 in electrical contact with the electrolyte, since that would mean aconsiderable loss in current between the walls of the stem portion of the valve and the tubular member. Where, however, the tubular member 25, or its equivalent, is to be used as a cathode, as in'my copending application Serial No. 482,378, filed April 9, 1943, now Patent No. 2,475,586, the stopoff coating would be omitted, and in that case the internal walls of the stem cavity lit-could be anodical'ly treated in accordance with the electro* polishing method of my copending application.

The lower end of the tubular member 25 is provided with a pin 36 extending laterally therefrom, to which is hingedly' attached a metal strip link 31, which may suitably be a strip of stainless steel about three-sixteenths of an inch in width. A similar strip of stainless steel 33 is hingedly connected, as at 39, to the free end of said strip 31. The hinge 39 may be formed in any suitable way, as by providing a pin 46 about which portions of the

strips

31 and 38 are bent for relative pivotal movement. A stainless steel wire GI is connected-to the free end of the strip link 38, as at 2, by a similar hinge connection. Said wire 41 extends from the hinge connection 42 through the

openings

34 and 33 respectively, in the

spaces

29 and 28, order to provide an extension portion 43 that may be manually manipulated to collapse or extend the

links

31 and 38 By pulling up onthe Wire 43, the

links

31 and 38 are collapsed into their more or less straight-line position, as illustrated in Figure 3, whereas when the wire 43 is depressed, the link 38 is extended laterally to conform in general, with the contour I however, be used satisfactorily, such as sulphuric of the end wall 44 ofthe head cavity 45 of the:

an electrical circuit, including lead wires t! and 48, connected, respectively, to the positive and negative terminals of a source of direct electric current. A switch 49- is positioned in the line 41', which is connected through an ammeter' 5n and a rheostat 53 to the valve M by means of a clamping band 52. The line 48 is connectedto' abare portion of the tubular member 25 by means of a clamping member 53. A voltmeter 54 is connected across the lines 4-! and-48 by means of a line 55. V

In operation, the reservoir 2| is provided with an aqueous electrolyte, preferably heated to a temperature of between about 50 and 150 F. The electrolyte that-I prefer to use is an aqueous solution of orthophosphoric acid, containing about 75% of orthophosphoric acid by weight of the solution.- Other aqueous electroytes may,

acid, or mixtures of sulphuric and phosphoric acids. The choice of the electrolyte will depend, in part, upon the metal or alloy of which the valve [4 is formed.

Suitable'metals and their alloys that might be used in the manufacture of hollow metal valves, such as the valve [4, include: nickel, chromium, and iron alloys such as Nichrome steel; nickel, molybdenum and iron alloys such as Hastelloy steel; non-ferrous nickel-chromium alloys such as Brightray; and cobalt, chromium and tungsten alloys, such as Stellite. I prefer to use orthophosphoric acid in the descaling of valves made of any of the foregoing metals or alloys.

At the start of the operation, the stop cook 23 is opened to permit the electrolyte 22 to pass through the flexible hose 25 into the tubular member 25, and thence into the interior of the valve l4. After the interior of the valve M has been filled with the electrolyte, the stop cock 23 is adjusted to permit a continuous, slow overflow of the electrolyte through the overflow opening 3| in the top spacer 28. The rate of fiow is not particularly important, but I have found that a how of about 2. cc. of electrolyte per minute is satisfactory. The excess of electrolyte that overflows through the opening 3! runs down over the outside of the valve 14 and drips into a catch basin 56.

As soon as the rate of flow ofelectrolyte has been adjusted, the circuit including the lines El and 48 is energized to pass an electrical current from the valve 14 as the anode, through the electrolyte filling the interior of the valve, to the active cathode consisting of the links 3! and 38. Since the portion of the tubular member 25 is coated with a stop-ofi lacquer or the like throughout the portion of said tubular member that is immersed in the electrolyte, n-o electrolytic action takes place at the external surface of said tubular member 25, but is confined

tothe links

31 and 38 and, to a slightv extent, to the wire 4|. The tubular member 25' nevertheless forms a conduc tor for the current back to the lead wire 48 through the clamping connection 53.

The current is applied to the internal circuit including the electrolyte at an applied voltage of around 4' volts, and the amperage is regulated by means of the rheostat 5i to deliver a current of about 5 amperes. During the course of the anodic treatment, whichmay require around forty-five minutes, the cathode electrode, comprising the strip links 3.? and 38' is rotated through about 45 every five minutes. This may be accomplished either by revolving the tubular member 25 together with the spacers 2-8 and 29 that are frictionally rotatable with said tubular member 25, or, more easily, by rotating the valve 14 within. the" ring support It. For this latter purpose, the: clamping member 52 may be loosened, if necessary. The purpose of the rotation of. the active cathode electrode is to secure uniform descaling ofthe interior wall of the valve head cavity 45.

At the completionv of the descaling operation, the electrical circuit is de-energized, the valve [4 disconnected from the electrical clamping member 52 and removed from the ring support 13. The electrolyte is poured out of the valve it and the valve then thoroughly rinsed in hot water until free from electrolyte. After the hot water rinse, the scale will be found to have been completely removed from the valve head interior and the surface will have a bright finish. While there may be a pitting effect due to the anodic action on the metal of the wall surface, such effect is not objectionable.

As mentioned above, the method of this application is somewhat analogous to that described and claimed in my Patent No. 2,475,586. In the electropolishing of the internal wall of the valve stem, as described in said patent, orthophosphoric acid is, also used as the electrolyte and the operating conditions are somewhat similar to those specified herein, except that a slightly lower current density is employed. In electropolishing, as distinguished from descaling, a proper value of current density is required to strike a practical balance between the time required to polish and the time within which pitting of the surface occurs at relatively high density. In the descaling operation, as here described, a relatively high current density is used to keep the operating time 5 within practical limits.

The same apparatus and practically the same conditions as herein described could, therefore, be used for the electropolishing of the internal surfaces of the valve head cavity 45, if that were desired. Practically the only change to be made in order to effect electropolishing would be to lower the current density by decreasing the current to about 2.5 to 3.5 amperes per valve, instead of 5 amperes. With a current of between 2.5 and 3.5 amperes per valve, the current density will run aboutv 0.5 ampere per square inch, so that with 5 amperes per valve, as in the descaling operation, the current density would be about 1 ampere per square inch.

The above described method of descaling the internal wall of the head cavity of a valve eliminates one of the greatest problems in the manufacture of hollow head valves for-use with metal coolants, such as sodium. The presence of scale in the interior of the hollow valve is very detrimental, since it contaminates the sodium and also greatly interferes with the cooling of the valve in the operation of an engine. By removing the scale, a surface having a much more eflicient rate of heat transfer is obtained. Furthermore, by the anodic descaling treatment of the interior surfac-es'of the wall of the valve, these surfaces are rendered more corrosion resistant and therefore less liable to attack by the liquid sodium most commonly used in the cooling of hollow valves.

While the method of my invention has been appended claim.

What I claim is:

Apparatus for effectingan anodic treatment of the internal surfaces of a hollow metal article having an enlarged head cavity, comprising an electrically conductive tubular member, a pair of spacers in spaced relation along said tubular member, each of said spacers having a fluid flow passage therein and an aperture to slidablyreceive an actuating wire therethrough, means for introducing a flow of an electrolyte through said tubular member, a collapsible conductive extension secured to one end of said tubular member, an actuating wire having one end secured to said collapsible conductive extension and extending through the apertures in said spacers in parallel spaced relationship to said tubular member for collapsingand extending said collapsible conductive extension, whereby when said apparatus is inserted in a hollow metal article, an electrolyte introduced through said tubular member will flow about said conductive extension and then through the fluid flow passages in said spacers.

KENNETH M. BARTLETT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS