US1759509A - Method of making pistons - Google Patents

Description

May 20, 1930. JARDINE 1,759,509

METHOD OF MAKING PISTONS Original Filed Sept. 25, 1926 INVENTOR Patented May 20, 1930 UNITED STATES PATENT OFFICE FRANK J'ARDINE, F CLEVELAND, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE ALUMINUM COMPANY OF AMERICA, 0]? PITTSBURGH, PENNSYLVANIA A CORPORA- METHOD OF MAKING PISTONS Original application filed September 23, 1926, Serial No. 137,194. Divided and this application filed March Serial No. 262,641.

This invention relates to a method of making pistons and the like. It is particularly adapted to the making of pistons composed of a plurality of different materials which have different co-eflicients of expansions and tend to produce great internal stresses in the pis- I tons when cast.

Pistons are frequently made of a plurality of different materials, as for example, aluminum or aluminum alloy pistons, in which are incorporated steel or iron members for restraining or controlling the expansion of the more expansible material. This type of piston is claimed broadly in my co-pending application, Serial No. 47,214, filed July '31, 1925. A common way of forming such pistons is to cast the main parts of the pistons about the control members so that these are 4 at least partly imbedded withiii the remainder of the pistons. Upon cooling after the casting operation the different materials tend to contract at different rates and thus set up great internal stresses.

It is an object of this invention toprovide a method of eliminating from such pistons some of the internal stresses normally set up therein and of relieving substantiallyall others.

The invention will be better understood from the description of one practical embodiment thereof illustrated in the accompanying drawings, in which Fig. 1 is a side elevation of a finished piston made according to the invention.

Fig. 2 is a longitudinal section thereof taken on the line 22 of Fig. 1.

fig. 3 is a bottom plan View of the piston, an

ing the piston casting before machining.

The piston has a head consisting of'a top 1 and a depending annular flange 2 which maythe head are walls 4 which carry wrist pin Fig. 4 is a view similar to Fig. 1, but show- I v p I 2 by cored slots 19. 'Thesecored: slots permit bosses 5 and 6 and are strengthened and stiffened by webs 7 and 8.

Below the piston head is a skirt comprising bearing or thrust faces 9 and 10 which are joined beneath the wrist pin bosses by straplike connectors 11. Bearing face 9 is shown as integrally joined to walls 4 by webs 12. The bearing faces are tied together and to the boss carrying walls by control members A and I B, shown as hollow squares having their ends embedded in ridges 13 on the inside of the bearing faces, and their sides spanning the space bet-ween the bearing faces, with the intermediate parts of the sides embedded in the boss carrying walls. The control members are of a material which will cause the, diameter of the piston to change only as desired, for instance at the rate of change of the cylinder in which it operates.

, The connectors 11 are split at 14 and the splits spanned by arcuate bridges or culverts 15, the splits and culverts allowing for the perimetrical expansion of the skirt.

Bearing face 9 is shown joined to the piston head by a relatively narrow neck or web 16 while bearing face 10 is separated from the head by an air gap 17.

The piston is made as follows The control members A and B are placed in a mold and the balance of the piston cast around them. The different contraction of the various parts of the piston upon cooling, 1

'the'outeredges of the bearing or thrustjfaces to adjust themselves independently of the head "and so prevent the production of some stressesboth in the faces {and head.

After casting, one or both bearing faces After this heat treatment the piston may be machined without tending to deform itself, thus considerably facilitating its manufacture.

This application is a division of my copendino application, Serial No. 137,194, filed on or a out Sept. 23, 1926, which application contains claims to the article shown in this present application.

While I have described one embodiment of my inventionewith some particularity, I do not limit myself to the precise details shown, but claim as my invention all variations and modifications thereof coming within the scope of the appended claims.

1. The process of making an insert piston which comprises casting the piston about the inserts, separating at least one bearing face from the piston head, heat treating at about- 300 F. for about 50 hours, and then machining the casting.

2. The process of relieving stresses in an insert piston which comprises separating one of the bearing faces of the piston skirt from the head and then maintainin the piston at a temperature of about 300 for about 50 hours.

3. The process of making an insert piston which comprises casting a piston blank having the bearing faces of the skirt integrally connected with the piston head at their centers and spaced therefrom at their sides by cored slots, separating one bearing face from the piston head, heat-treating at about 300 F. for about 50 hours, and then machining the casting.

4. The process of making an insert piston which comprises casting a piston blank with the bearing faces of the skirt thereof integrally connected to the head at their centers and spaced therefrom at their sides by cored Y slots, partially machining the blank, heattreating the blank at about 300 F. for about 50 hours, and then finishing the machining of the blank. I

5. The process of making an insert piston which comprises casting a blank with hearing faces joined at their centers to the head and spaced therefrom at their sides by cored

Images