US2481025A

US2481025A - Method of making shafts having sheet metal journal surfaces

Info

Publication number: US2481025A
Application number: US635327A
Authority: US
Inventors: Gustav H Koch
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1945-12-15
Filing date: 1945-12-15
Publication date: 1949-09-06
Anticipated expiration: 1966-09-06

Description

Sept. 6, 1949. H, KOCH 2,481,025

METHOD OF MAKING SHAFTS HAVING SHEET METAL JOURNAL SURFACES Filed D60. 15, 1945 INVENTOR Gusnv M-Kacu ATTORNEY wn massss:

Patented Sept. 6, 1949 METHOD OF MAKING SHAFTS HAVING SHEET METAL JOURNAL SURFACES Gustav H. Koch, Springfield, Mass., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 15, 1945, Serial No. 635,327

1 4 Claims.

My invention relates to a method of making a shaft having a sheet metal journal surface.

Heretofore, shafts which include a journal surface and also a crank portion have been made from two separate parts, one a die-cast crank member and the other a steel shaft which is centerless ground and milled after forming in a screw machine, the two parts being assembled together by riveting.

It is an object of my invention to provide a method of making a shaft having a satisfactory journal surface, more particular objects being to provide a method that may be carried out at low cost and to provide a method that produces an accurate cylindrical journal surface.

In accordance with my invention, a liner, made of a suitable metal such as steel and having a smooth surface, is provided to form the journal surface and the remainder of the shaft, including the crankshaft portion, is cast into the steel liner. The pressure of the molten metal is utilized to force the steel liner outwardly against the accurately formed cylindrical bore of a die sleeve, thereby providing an accurately formed journal surface requiring no further machining or grinding.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a longitudinal section of a shaft made in accordance with my invention;

Fig. 2 is an end view of the shaft;

Fig. 3 is a transverse section taken on line III-III of Fig. 1;

Fig. 4 is an end view of the shaft;

Figs. 5 and 6 are side and end views of the partly formed steel liner;

Fig. 7 is a perspective view of the liner in substantially final form; and

Fig. 8 is a sectional view showing the shaft and the die.

Referring to the drawing in detail, I show a shaft II] which, in this instance, is the oscillating shaft used in the oscillating mechanism of an electric fan. The shaft includes a disc II at one end formed with a recess l2 and a slot I3, as clearly shown in Figs. 1 and 2. At the opposite end, the shaft includes a portion 19 which is square in cross section.

The shaft is further provided with a cylindrical journal surface H which, in accordance with the present invention, is formed by a steel liner I5.

. The liner I5 includes a cylindrical portion and two flanges l6 which extend inwardly from the meeting edges of the cylindrical portion, as clearly shown in Figs. 3 and 7. The remainder of the shaft I0 is a die casting, for example, a zinc die casting.

In making the shaft, polished steel shim stock is used to form the liner which provides the journal surface. The liner may have a thickness of, for example, .005 of an inch. The fiat shim stock, in rectangular form of suitable dimensions, is first bent to the form shown in Figs. 5 and 6, including flanges l6, curved portions l7 and a fiat central portion [8. In bending the flanges IS, the distance between the lines along which these flanges are bent is closely controlled so that the periphery of the liner, as shown in Fig. 7, will be that of the desired journal surface. It is then formed to the shape shown in Fig. 7, in which the curved portions I7 and the flat portion 18 have been formed into a cylindrical portion and in which the adjacent sides of the flanges l6 bear against each other.

In the die casting operation, there is employed a die having an accurately formed cylindrical bore. For example, a die as shown in Fig. 8 may be used. This die comprises two die members 2| and 22 and a die sleeve 23 which has an accurately formed cylindrical bore 24 therein. The die member 22 includes

parts

25 and 26 which form the recess l2 and the slot l3. The die is also provided with a gate at any suitable point, for example, along the plane of division between the die members. In Fig. 8, a gate 21 is shown at the top for clarity of illustration. The steel liner, after having been formed to the shape shown in Fig. 7, is inserted in the die sleeve 23. The initial tension or resilience holds the liner tightly against the surface of the die sleeve. The die sleeve 23 is then positioned between the die members 2i and 22, as shown in Fig. 8. The molten die casting metal, preferably zinc, is then admitted through the gate 21. It is admitted under high pressure, such as 500 to 4000 pounds per square inch. As will be apparent from Fig. 7, the molten metal is admitted to the interior of the liner sleeve l5 and the high pressure thereof forces the liner firmly against the accurately formed cylindrical surface 24, thereby providing an accurately formed cylindrical journal surface. It is a characteristic of die-casting operations of this character that the molten metal does not enter, to any appreciable extent, the slight crevices that may and usually do exist between the liner and the die sleeve, so that the pressure of the molten die-casting metal within the liner sleeve is effective to force the same against the cylindrical bore 24 of the die sleeve. When such molten metal starts into a small crevice between the liner and the die sleeve, it is chilled by such parts, which are at a temperature lower than the melting point of the molten metal, and thus the metal is prevented from flowing further intothe crevice.

After the casting operation is completed, the die members 2| and 22 are separated and the die sleeve 23 and shaft are removed therefrom, the

parts

25 and 26 being withdrawn from the recess 12 and the slot 13: The die sleeve 23 is withdrawn axially from the shaft.

There is thus produced a shaft which, except for the forming of the liner, is provided by" a; single casting operation. The forming of the liner into the proper shape may be effected by simple operations in a punch press. The flanges 16 are firmly anchored within the" die casting and thereby secure the liner firmly on the shaft.

While I have shown my invention in but one form, it will be obvious to thoseskilled inthe art that it is not so limited, but is susceptible" of various changes and modifications without departing from the spirit thereof.

What I claim is:

1. The method of making a shaft having a cast-in, sheet metal journal'surface, which moth od comprises forming a piece of sheet metal to form a cylinder and flanges extending inward-1y from meeting edges of the portion forming the cylinder, placing said sheet metal in the cylin drical bore portion of a die, delivering molten casting material under pressure into the interior of the cylindrical sheet metal, and forcing said sheet metal by such pressure against the cylin drical surface of said die, thereby forming a shaft and an accurate cylindrical journai surface thereon.

2. The method of making a shaft having a; cast-in sheet metal journal surface, whichmethod comprises folding a. sheet metal to form a cylinder, inserting said sheet metal into the cylindrical bore of a die having an accurately formed cylindrical bore, delivering molten casting material under pressure into the cavity in said die 4 including the interior ofsaid liner, and forcing the sheet metal by such pressure against the cylindrical surface of said die, thereby forming a shaft and an accurate cylindrical journal surface thereon.

3. The method of making a shaft having a cast-fir sheet metal journal surface, which method comprises folding a sheet metal to form a cylinder, inserting said sheet metal into the cylindrical bore portion of a die sleeve, placing said die sleeve between two die members, delivering molten casting material under pressure into the cavity formed by said die members including the interior of said liner, and forcing the sheet metal by such pressure against the" cylindrical surface of said die sleeve, thereby formingv a shaft and an accurate journal surface thereon.

4a The method of making a shaft having a sheet metal journal surface, which method comprises folding a piece of sheet metal to'form a cylinder and flanges extending inwardly from meeting: edges of said cylinder disposed parallel tothe axis of said cylinder in the cylindrical bore, placing said die sleeve between two die members, delivering molten casting material under pressure into the cavity formed by the die members and into the interior ofthe cylindrical sheet metal, and forcing the sheetmetal by such pressure againstthe surface of said cylindrical= bore, thereby forming. a shaftand are accurate cylindrical journal surface thereom GUSTAV KOCH.

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

UNITED STATES PA'I'ENTS Date