Ford Motor Company Limited

Robert R Baker

Richard L Allor

Dale L Hartsock

To induce fracture under test conditions for a tool bit configuration held in a laterally restrained condition, but with freedom to move up and down, a series of members (hardened steel ball bearings) are selected as to size, butted together, and constrained so that such members make tangential point contact with a constrained bit at locations close to the corners of one end surface supported on the members. When a centralized load is imposed on the opposite end surface of the bit, stress forces can be set up on the bit to result in a body bend fracture or an edge chip fracture, depending on how close the point contacts are to a curved sector. Each point contact is located along a radius bisecting a corner sector, the location being spaced from the sector a distance either (a) of at least one-half the sector radius, but within 0.01875-0.0312 inch, to induce edge chip fracture, or (b) of at least the sector radius, but no less than 0.0625 inch, to induce bend strength fracture.

Device for directly analyzing strength of ceramic tool bits

This disclosure relates to an improved method for achieving the best bond strength and for minimizing distortion and cracking of hot pressed articles. In particular, in a method for hot press forming both an outer facing circumferential surface of and an inner portion of a hub, and of bonding that so-formed outer facing circumferential surface to an inner facing circumferential surface of a pre-formed ring thereby to form an article, the following improvement is made. Normally, in this method, the outside ring is restrained by a restraining sleeve of ring-shaped cross-section having an inside diameter. A die member, used to hot press form the hub, is so-formed as to have an outside diameter sized to engage the inside diameter of the restraining sleeve in a manner permitting relative movement therebetween. The improved method is one in which several pairs of matched restraining sleeve and die member are formed with each matched pair having a predetermined diameter. The predetermined diameter of each matched pair is different from another matched pair by stepped increments. The largest inside diameter of a restraining sleeve is equal to the diameter of the outer facing circumferential surface of the hub. Each pair of the matched restraining sleeve and die member is used to form an article in which an inside hub is bonded to an outside ring. The several samples so-formed are evaluated to determine which sample has the best bond formed between the hub and the ring with the least or no cracking or distortion in the ring portion of the article. Thereafter, the matched restraining sleeve and die member which form the article having the best bonding characteristics and least distortion cracking is then used for repeated formations of articles.

Method for hot press forming articles

This invention is directed to a specially designed apparatus for bonding a ceramic body to an interior annular surface of a ring shaped body formed of ceramic material. Various specially designed elements are described which permit one to assemble the apparatus and use the same under elevated temperature conditions to bond the ceramic body to the mentioned interior annular surface of the ring shaped body. The apparatus is so designed that all of the elements thereof remain in a centered position during the bonding operation. The apparatus reduces the drag load on the various elements during the bonding operation.

Apparatus for forming ceramic bodies

This invention is directed to a process for preventing the cracking of ceramic bodies during a hot pressing operation. The method is accomplished by applying a relatively thin layer of a release material to surfaces of the ceramic body which are to be load reaction surfaces during the hot pressing operation. A relatively thick layer of the release material is applied to surfaces of the ceramic body which are not to be load reaction surfaces during the hot pressing operation.

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Livonia, MI, United States of America

Robert R Baker