US2285811A

US2285811A - Method of finning

Info

Publication number: US2285811A
Application number: US362580A
Authority: US
Inventors: Arthur W Gay
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-10-24
Filing date: 1940-10-24
Publication date: 1942-06-09
Anticipated expiration: 1959-06-09

Description

June 9, 1942. A. w. GAY

METHOD OF FINNING "Filed Oct. 24. 1940 2 Shee'Es-Sheet 1 R v 0 W n I? A U June 9, 1942. A. w. GAY

METHOD OF FINNING' Filed Oct. 24, 1940 2 Sheets-Sheet 2 INVENTOR. flerwut V14 64 Y ATTORNEY.

Patented June 9, 1942 UNITED STATES PATENT OFFICE ME'rnonoF FINNING Arthur W. Gay, Akron, Ohio Application October 24,1940, Serial No. 362,58ll ((122-204) 12 Claims.

, of a cylinder barrel of an air-cooled internal combustion engine of the type commonly employed in the aircraft industry, where rapid and eflicient heat dissipation is required to minimize engine efiiciency losses and the failure of engine parts due to operation at unduly high temperatures. Dissipation of the heat rapidly enough from the cylinder barrel so that the temperature of the engine will not become such, as to adversely afiect its operating efilciency, can be accomplished only if there is a free and unimpeded fiow of heat from the wall of the cylinder barrel into the fins.

Various methods have been employed hereto-- fore for providing such cylinder barrels with cooling fins. These methods have included the manufacture of cylinder barrels with integral cooling fins, either by casting them as a part of the barrel or providing the barrel withsufilcient wall thickness so that fins could be machined therein. It has been found that there were many undesirable features inherent in barrels with integral fins, among which were the inability of the limited heat dissipating surface areas provided on these barrels to effect an adequate or desired cooling of the engine; poor thermal conductivity of the material comprising the cylinder barrel and the fins; excessive weight of the barrel if an attempt were made to obtain suficient cooling surface area by enlarging or spacing the fins closer together; and a relatively high cost of manufacture. Another method of firming barrels embodied the use of preformed fins. Where such fins were employed and secured to the cylin- .der barrel by any of the well-known methods,

such as shrinking, soldering, brazing, welding, or the like, it was found that these methods were not particularly acceptable to the production '01 finned cylinder barrels for use in airc'raftenglnes. Although sumcient heat dissipating surface area could be obtained, it was ineffective due to the unreliability and poor thermal conductivity of the Joint between the barrel and the fins, which precluded a rapid or free flow of heat thereacross.

Furthermore, the joint was not strong enough result that the fins became loosened or separated from the cylinder barrel. Nor were mechanical weaknesses and poor conductivity the only disadvantages resulting from the use of soldering,

brazing, or welding. Where the barrel was made of a special alloy, the heat attending the practice of these processes seriously afiected essential characteristics of the metal comprising the barrel or precluded the use of certain desirable metals for the preformed cooling fins.

The present invention embodies a new and improved method of producing cylinder barrels for internal combustion engines with preformed cooling fins made of a metal having relatively high thermal conductivity, the product produced thereby being free from substantially all of the aforementioned drawbacks of cylinder barrels produced by prior practices. The amount of e!- fective heat dissipating surface area can be increased to any desirable amount with minimum increase in the weight of the engine member. The Joint between the cooling fins and the cylinder barrel is substantially free from insulating mediums and permits the free flow of heat from the cylinder barrel to the cooling fins; moreover, the finned barrel can withstand severe service conditions without the this becoming detached or separated from the barrel. These advantages are all attained without any undue or excessive cost in manufacture.

The method of the present invention for producing an article embodying the invention, may be briefly described as including the steps ofplacing a metal coating on that portion of the outer wall of the cylinder barrel to which the cooling fins are to be attached, assembling preformed fin members in spaced relation to the coated portion of the cylinder barrel, heating the assembled fins and barrel to difierent predetermined temperatures and then securing the fin members to the outer surface of the barrel wall by casting preferably a metallic mull or sleeve about the barrel, the mull being bonded to the wall of the barrel with the inner edge portions of the fins secured thereto.

Various objects and advantageous features of the invention not at this time more particularly to withstand severe service conditions, with the B5 enumerated, will'become more apparent as the nature of the invention is better understood from the following detailed description taken in con- Junction -with the' accompanying drawings,

present invention,

Figure 2 is a sectional view taken on the line 2-2 of Figure 1,

Figure 3 is an enlarged fragmentary sectional view taken on the line 3-3 of Figure 2, Figure 4 is a fragmentary side elevational view partly in section of apparatus which may be employed for securing preformed fins to cylinder barrels in accordance with the teachings of the Figure 5 is an enlarged fragmentary top plan view of the apparatus illustrated in Figure Figure 6 is a sectional view, taken on the line 6-6 of Figure 5, and

Figure '7 is a fragmentary sectional detail of the apparatus.

With reference to Figures 1 to 3, inclusive, of the drawings, the numeral 10 designates a cylinder barrel of an' air-cooled internal combustion engine having the usual hold-down flange ll,

and threads l2, onto which the cylinder head (not shown) is threaded and shrunk in the usual manner. The outer surface of the barrel is provided with a plurality of preformed relatively thin cooling fins I3, the inner edge portions of which are embedded in a cast muff H, which is bonded to the exterior wall of the cylinder barrel. I

' The joint between the wall of the cylinder 10 and the muff I4, is characterized by having high thermal conductivity thereacross. The number, size, and distribution of the fins mounted on the exterior of the barrel wall can be varied to provide sufficient heat dissipating surface area to 'meet the desired cooling requirements of the particular cylinder barrel. Although the fin members may be made of any suitable metal having high thermal conductivity, I have found that where the combination of lightness and rapid heat dissipation is particularly desired in the fin ished article, aluminum has proven to be the most acceptable for the fins l3 and muff II.

More particularly, the new and improved method of the present invention for providing -,to insure complete filling of the cavity and a porosity free mud. The barrel is then cooled this point it is removed from the bath and rotation is continued in a horizontal position at a speed sufiicient to maintain the coating metal uniformly distributed over the surface of the barrel until it has solidified. When the thus treated barrel is cooled, the metal coating can be freed of any adherent particles of fiux and other foreign material by wire brushing under a stream of water. It has been found that by this method a substantial coating is applied on the barrel and it is desirable in certain cases to remove a portion thereof by taking a lathe cut on the coated surface of the barrel.

The preformed fins, w,hich may or may not have the inner edge portions treated with a high melting aluminum solder, are assembled in a suitable mold or fixture and the assembly heated to a predetermined temperature preferably between 1000 F. and 1060 F. During the time that the assembled mold and fins are being heated to the desired temperature, the treated barrel is also heated to a predetermined temperature,

preferably between 500 F. and 550 F. When the barrel and the mold have been heated to their respective predetermined temperatures, the barrel is inserted within the mold and the assembly prepared for casting the mufi. The barrel is so disposed within the mold that the fins carried by the mold are positioned in proper spaced relation along the coated portion of the barrel wall. Molten aluminum is cast into the cavity defined by the inner edge portions of the fins and the barrel wall, completely filling the same. The molten aluminum may be cast, under pressure with certain types of apparatus, or it may be cast by gravity feed. In either casewthe mold assembly is vibrated during the ,ksasting operation to approximately room temperature, removed from the mold, degated, trimmed, and is then cylinder barrels with preformed cooling fins mounted on the exterior surface thereof, consists of first cleaning that portion of the exterior surface of the barrel which is to receive the fins. Such cleaning-includes the heating of the barrel to a predetermined temperature, preferably between 500 F. and 600 F., until all organic or volatile substances are removed. When the barrel has sufficiently cooled, that portion of the barrel to be finned is then polished or given a lightlathe cut to remove the extraneous matter on the surface caused by the previous heating.

The surfaces of the barrel, except that to which the fins are to be subsequently applied, is covered with a film of masking material such as a chromic acid solution which is baked on the barrel at a temperature of between 250 F.

and 300 F., to protect or mask such surfaces during the subsequent coating and finning operations. When the barrel has become sufiiciently cool, the outer wall portion to be finned is apparatus includes a cylindrical mold portion ready to be provided with a coating of a relatively low melting metal, which is preferably'zinc or an alloy of zinc.

In applying this coating the barrel wall is wetted with a saturated aqueous solution of zinc chloride. The barrel is then introduced into a metallizing bathand continuously rotated while immersed therein. The barrel is disposed within the bath, which is covered with a coating of molten zinc chloride, until it has reached a temperature'equal to the temperature of the metal bath, preferably between 825 F. and 850 F. At

broadly indicated by the numeral 20 which serves to position the preformed ring-like fin members 93 with respect to the barrel I0 during the casting of the muff I4. The mold portion 20 is preferably formed in quadrants, each of which consists of an arcuate base member'2l and an arcuate collar 22, interconnected by means of

vertical posts

23 and 24. The lower ends of the

posts

23 and 24 seat in spaced-bores 25 formed in the base member 2| and are maintained therein by pins 28 traversing the bores 25 and engaging the

posts

23 and 24. Similarly the upper ends of the

posts

23 and 24 extend through openings 21 in the.

collar segment 22 and are secured therein by means of the pins 28.],

Between the collar segment 22 and the base member 2 I are disposed in stacked relation a plu-, rality of arcuate spacers 30 having notched corners 3| which engage about the posts 23. The spacers 30 are freely moveable along the posts 23 and and are adapted to receive them between the fin members If. The thickness of v the spacers roughly determines the space between adjacent fins. However, the collar segment 22 is spaced from the base segment a distance slightly greater than the total thickness of the fins and spacers to allow for expansion during the casting operation, and the subsequent removal of the spacers. When the quadrants are positionedabout a barrel the edges of the spacers and the fin members are spaced from the barrel and define a mold cavity 32 into which molten aluminum is cast to form the muff.

The base quadrants 2| are provided with downwardly, outwardly inclined inner surfaces 34 which in conjunction with the adjacent barrel wall define an enlarged space about the barrel which serves as a circular gate for directing the molten metal into the mold cavity 32. The lower surface of the quadrants 2! are provided with a peripheral cut-away portion which receives the upwardly extending flange 31 formed on the upper surface 36 of a bottom gate casting 35. The surface 38 and the flange 31 are adapted which includes the steps of providing that portion of the exterior of a cylinder barrel which A is to receive the fins, with a coating of a metal alloy having a relatively. low melting point, as-

sembling ring-like aluminum fin members in.

- cylinder barrel wall which is to receive the fins with a bonding metal or metal-alloy having a relatively low melting point, assembling ring-like aluminum fin members in a mold and heating the same to a predetermined temperature, a

U mounting the barrel within said mold and then to receive, position, and support the quadrants of the mold portion 20. Mounted on the upper end of the mold portion 24 and serving to maintain the, collar quadrants thereof in proper assembled relation, is a ring 42 which is provided with a down-turned flange 43 seating within a a peripheral cut-away portion of the collar segments 22.

The bottom gate casting 3' is provided with a cup-shaped. interior 3| terminating in acen-' tral opening 3! through the base thereof. Mounted within the member SI is-a closure member 48 having'an outer surface spaced from the surface 38 and cooperating therewith to define a continuance of-the circular gate. The closure member 48 is provided with a flange 49 which is adapted to extend into the lower end of thebarrel It. The member 46 is maintained in proper position with respect to the end of the barrel by means of a bolt 41 which extends downwardly through the interior of the barrel. The upper end of the bolt 41 extends between spaced frame members 50 engaging theend of the barrel and receives the adjusting nut I.

For clamping the unit together there is provided hook members I2, the lower ends of which are adapted to engage the bottom of the member 88 and the opposite ends are threaded to receive tightening nuts 53 which engage plates I4 extending across the extremities of the frame members 50.

The opening 39 in the'gate casting is adapted to receive'the upper end of a conduit 60 extendingupwardly' from the bottom of a ladle 8| normally filled with molten metal at a predetermined casting temperature. metal is conveyed from the ladle Si by means of gas pressure exerted on the-surface of the molten metal. The gas under pressure is introduced into the ladle through the connection I! which is connected to a suitable supply by means of conduit 63.

Having thus described my invention so that those skilled in the art may be able to understand and practice the same, what I desire to obtain by Letters Patent is defined in the appended claims.

I claim:

1 The method of producing a cylinder barrel of a; ferrous metal alloy for an air-cooled internal combustion engimr'withpreformed aluminum cooling fins on the exterior surface thereof securing the fin members'to the barrel by casting an aluminum sleeve about said barrel, said sleeve being bonded to the wall of the cylinder barrel and having the inner edge'portions of thefin members. secured thereto. 1 I

3. The method of producing a cylinder barrel of a ferrous metal alloy for an air-cooled inter nal combustion engine with preformed cooling fins on theexterior surface thereof which in-' cludes the steps ofassembling ring-like, aluminum fin members in a mold and heating same to a temperature of between 1000 F. and 1060 F.,' heating a cylinder barrel to a temperature of between 500"F. and550 F. and. then securing the fin members to the barrel by casting an aluminum sleeve about-said barrel, said sleeve being bonded to the wall of the cylinder barrel and having the inner edge portions of the fins embedded therein. 4. The method of producing a cylinder bar- -rel of a, ferrous metal alloy for 'an'air-cooled internalcombustion engine with preformed cooling fins on the exterior surface thereof which includes the steps of applying a metallic coating to that portion of a barrel wall which is to receive the fins, assembling ring-like aluminum fin members in a mold and heating same to,

a temperature of between 1000 F. and 1060 F.,

heating the coated barrel to a temperature ofbetween 500 F. and 550 F., assembling thebarrel within the mold and then securing the fin members to the barrel by casting an aluminum sleeve about said barrel, said sleeve being bonded to the wall of thecylinder barrel and having the fin members embedded therein.

5. The method of producing a cylinder barrel of a ferrous metal alloy for an air-cooled inter- The molten nal combustion engine with preformed cooling fins on the exterior surface thereof which includes the steps of applying a metallic coating to the exterior wall portion of a cylinder barrel, assembling ring-like aluminum fin members in spaced relation along the coated portion of the barrel and forming therewith a casting cavity, securing the inner edge portions of the fins to the barrel wall by casting metal into the casting cavity, and vibrating the barrel and mold assembly during the casting operation.

6. The method of producing a cylinder barrel of a ferrous metal alloy for an air-cooled internal combustion engine with preformed cooling fins on the exterior surface thereof which includes the steps of applying a metallic coating to that portion of acylinder barrel wall which is to receive the preformed fins, heating thebar- I relto a predetermined temperature, assembling the barrel in a moldcontaining preformed ringlike aluminum fin members, casting molten metal into the cavity formed between the barrel wall and the mold to secure the fin members to the barrel wall, and vibrating the barrel and mold assembly during the casting of the metal.

7. The method of producing a cylinder barrel of a ferrous metal alloy for an air-cooled internal combustion engine with preformed aluminum cooling fins on the exterior surface thereof which includes the steps of applying a metal coating to that portion of a cylinder barrel wall which is to receive the preformed fins, heating the barrel to a predetermined temperature, simultaneouslyheating a mold assembly containing preformed fin members to a different predetermined tem- 3 perature, positioning the heated barrel within the mold assembly and castingmolten metal into the cavity formedbetween the barrel wall and the mold to secure the fin members to the barrel wall, and vibrating the barrel and mold assembly during the casting of the metal;

8. The method of producing a cylinder barrel of a ferrous metal alloy for an air-cooled internal combustion engine with preformed cooling fins on the exterior surface thereof which includes the steps of applying a metal coating to that portion of a cylinder barrel wall which is to receive the preformed fins, heating the barrel to a temperature of between 500 F. and 550 F, simultaneously heating a'mold assembly including preformed ring-like aluminum fins to a temperature of between 1000 F. and 1060 F., posifins on the exterior surface thereof which includes the steps of cleaning the wall of a cylinder barrel to provide a surface free of all volatile or extraneous matter, applying a relatively thin metallic coating to said surface, heating the barrel to a temperature of between 500 F. and 550 F., simultaneously heating a mold assembly ineluding preformed aluminum fins to a temperature of between 1000 F. and 1060 F., positioning the barrel within the mold assembly and casting molten aluminum into the cavity defined by the barrel wall and the mold to secure the fins to the barrel'wall. r

10'. The method of producing a cylinder barrel of a ferrous metal alloy for an air-cooled internal combustion engine with preformed cooling fins on the exterior surface thereof which includes the steps of cleaning the exterior wall. of a cylinder barrel to provide a surface free of all volatile or extraneous matter, applying a relatively thin metallic coating to said surface, heating the barrel to a temperature of between 500 F. and 550 F., simultaneously heating a mold assembly including preformed aluminum fins to a temperature of between 1000 F; and 1060 F., positioning the barrel within the mold assembly and casting molten aluminum into the cavity defined by the barrel wall and the mold to secure the fins to the barrel wall, and vibrating the mold assembly and barrel during the casting of the metal.

11. The method of producing a cylinder barrel of a ferrous metal alloy for an air-cooled internal combustion engine with preformed cooling fins on the exterior surface thereof which includes the steps of cleaning'the exterior wall of a cylinder barrel to provide a surface free of all volatile or extraneous matter, applying a relatively thin metallic coating to-said surface, heating the barrel to a temperature of between 500 F. and 550 F., simultaneously heating a mold assembly including preformed aluminum fins to a temperature of 1000'F. to 1060 F., mounting the barrel: within said mold and then securing the fin members to the barrel by casting a sleeve about said barrel, said sleeve being bonded to the wall of the cylinder barrel and having the inner edge portions of the fin members imbedded therein. I

12. The method of producing a cylinder barrel of a ferrous metal alloy for an air-cooled internal combustion engine with preformed cooling fins on the exterior surface thereof which includes the steps of cleaning the exterior wall of a cylinder barrel to provide a surface free of'all volatile or extraneous matter, applying a relatively thin metallic coating to said surface comprising a zinc alloy, heating the barrel to a temperature of-between 500 F. and. 550 F., simultaneously heating a mold assembly including preformed-aluminum fins to a temperature of 1000" F. to 1060 F., mounting the barrel within said mold,- securing the fin members to the barrel by casting a sleeve about said barrel, and vibrating the mold assembly and barrel during the casting operation, said sleeve being bonded to the wall of the cylinder barrel and having the inner edge portions of the fin members embedded therein. ARTHUR W. GAY.