US2297491A - Method of manufacturing tubular composite metal bodies - Google Patents

Description

p E. MEIER, JR 2,297,491

METHOD OF MANUFACTURING TUBULAR COMPOSITE METAL BODIES Filed Sept. 11, 1940 A TTORNEVY Patented Sept. 29, 1942 METHOD or MANUFACTURING TUBULAR COMPOSITE METAL BODIES Ernst Meier, Jr., Brunswick, Germany; vested in the Alien Property Custodian Application September 11, 1940, Serial No. 356,395

In Germany July 4, 1939 4 Claims. (Cl. 22-203) My invention relates to improvements in the method of manufacturing tubular composite metal bodies, and more particularly in the method in which a tubular body and more particularly a bearing is made from a main body of cast iron or steel and a suitable bearing metal such as lead bronze applied thereto. The object of the improvement is to provide a method by means of which the said bearing metal is intimately united with the body of steel or cast iron, which is simple in operation, and in which no valuable bearing metal is wasted, and with this object in view my invention consists in first melting the said bearing metal at a temperature not much higher than the melting point, applying the molten metal to the cold base body of cast iron or steel, and thereafter heating the said base body for a short period of time at a temperature higher than the melting temperature of the bearing metal and sufficient to insure a perfect binding by diffusion of the bearing metal to the base body. I have found that in this method the surface of the base body to which the bearing metal is applied is not oxidized by the moderately heated molten bearing metal, so that the metallic surface of the base body is maintained and no layer of oxidized metal is produced between the base body and the molten bearing metal.

Further, when subsequently high heat is applied to the base body, the said surface of the base body can not be oxidized, because the molten metal prevents access of oxygen to the surface of the base body, and therefore the bearing metal is intimately united by diffusion with the base body.

Preferably high heat is applied to the base body by means of a high frequency electric current, or by means of gas burners.

In any case after heating the base body at high temperature it is abruptly cooled or quenched, for example by means of cold water sprayed against the body or by immersing the said body into a bath of oil.

An important feature of the method is that the tubular body-of steel or iron is not heated before the molten bearing metal is applied thereto, and therefore a thinlayer of bearing metal is produced thereon which at first is not united by diffusion to the base body, and which is rapidly cooled and solidified on the base body which therefore has no time to oxidize.

reference characters have been used in all the views to indicate corresponding parts. In said drawing Fig. l is an elevation partly in section showing the apparatus used for heating and subsequently quenching the tubular body, the tubular body being shown in section, and

Fig. 2 is a perspective sectional view showing one of the members of the apparatus.

For the purpose of explaining the invention it may be assumed that it is desired to provide a tubular body a of steel with an internal lining c of a suitable bearing metal such as lead bronze. The said composite body may be a bearing.

In carrying out the method the inner surface of the body is first freed of any impurity or oxidized coating, and thereafter a thin layer of bearing metal 0 heated at a temperature not much higher than melting temperature is applied to the inner surface of the base body a, preferably by first placing a core b into the body a. It will be understood that at the beginning of this operation the base body a is at room temperature, and that it is not heated before thelining is applied.v After the lining has thus been applied, the base body and its lining are placed into an apparatus for rapidly heating the base body at high temperature, and heat isapplied thereto. In the construction shown in Fig. 1, the said apparatus comprises a pair of tongs having a pivot bolt d and adapted to be clamped together at their free ends by means of a screw and nut 'm. The members of the tongs are formed each with a semi-cylindrical portion f having an inner diameter slightly larger than the outer diameter of the base body a so that the For the purpose of explaining the invention an I example embodying the same has been shown in base body is embraced by the portions 1 without making contact therewith and with little clearance. The tongs consist of metal of high conductivity for electricity and heat such as copper, and the members of the tongs are metallically connected with each other only through the pivot bolt d while they are insulated from each other at e. To the outer ends of the tongs leads g, g are secured which are connected with a source of strong high frequency current, for example to a source of high frequency alternating current having about 3000 oscillations per second.

The base body a may be held out of contact with the tongs by suitable insulating material, such as pads of asbestos placed between the portions 1 and the base body a. Preferably the lower member of the tongs ,f is fixed to a suitable the accompanying drawing in which the same Ibase while the upper member I may be turned around the pivot 11 and away from the base body plied for holding the members of the tongs together. Now the parts are in the positions shown in Fig. 1, in which the members I, I are insulated from each other with the exception of the left hand ends thereof, and in which further, the portions 1 are slightly spaced from the base body (1. Now a strong high frequency alternating current is applied to the conductors Now the members 7 of the tongs act as the coil of an electromagnet, by magnetizing the steel body a alternately in opposite directions. By the rapid change in the magnetization of the steel body the temperature of the base body a and it lining is increased, within a few seconds, to a temperature higher than the melting point of the bearing metal 0.

At this high temperature difiusion takes place between the base body a and the bearing metal c, which insures intimate binding of the metals.

When this state is attained the current is interrupted, and the steel body is rapidly cooled. In the construction shown in the figures cooling is effected by means of jets of water sprayed against the outer surface of the base body a and for this purpose the portions ,f are formed with annular chambers n each connected to a supply of cooling water through flexible tubes h, and the chambers 11 open internally through bores or nozzles i through which jets of cooling water'are thrown vide base bodies a. of the desired length and-ap-' ply thereto the lining c of bearing metal by means of a suitable core, all the blanks being placed on a conveyer band below a casting apparatus by means of which an exceedingly thin layer of lead bronze is brought into the space between the body a and the core of sand. Thereafter the blanks are passed on the-conveyor band through a furnace in which the flames of gas burners are directed to the outside of the body 1 whereby the said base bodies are heated a short period of time at a temperature higher than the melting temperature of the bearing metal. Thereby the metals of the base body and the lining diffuse into each other, and the metals are intimately united according to the period of time during which heat is applied. The gas burners may be disposed within the furnace so that the treated for completing the bearings.

A bearing made by my improved process may be made with a very thin lining of bearing metal, it has the crystal uniformly distributed therein for developing the desired qualities in the bearing and therefore it is particularly suitable for use in air craft.

I claim:

1. A method of making composite tubular bodies, comprising the steps of melting metallic material of comparatively low melting point, applying the same as a lining to the interior of a metallic tubular member of relatively high melting point, which member is at room temperature, thereafter heating the composite body to a temperature above the melting point of the lining material, and thenv rapidly cooling the same,

whereby the lining metal is compressed due to shrinkage of the outer tubular member to perfeet the union between the inner and outer layers of the composite body.

2. A method of, making composite tubular bodies comprising the steps of cleansing the inner surface of a member composed of metal of high melting point, melting metallic material of comparatively low melting point, applying the same as a lining to the interior of said curved metallic member of relatively high melting point, said member being at room temperature, thereafter heating the composite body so formed to a temperature above the melting point of the lining material, and then rapidly cooling said body so as to perfect the union of the inner and outer layers of said body due to th compressing ac tion caused by shrinkage of said outer member after solidification of the inner layer of metal.

3. The process of manufacturing unitary laminated tubular bearings comprising placing a steel tube in a metallic jacket, placing a core in the tube, pouring molten bearing metal between said tube and core to line the tube while the tube is at room temperature, passing a high frequency current through said jacket to heat the lined tube rapidly to a temperature above the melting point of the lining thereof, and maintaining the heat for a suflicient period of time to permit diffusion of the molten metal into the metal of the steel tube.

4. A process as in claim 3, including the step of suddenly chilling the tubular body upon completion of the heating operation.

ms'r MEIER, JR.

Images