GB785533A - A method and apparatus for improving the physical properties of metal members - Google Patents

Abstract

785,533. Altering physical structure; making engineers' toots and gun barrels. WLODEK, T. W. Jan. 18, 1954 [June 11, 1953], No. 1373/54. Classes 83 (2) and 83 (4). A method of improving the physical or stress sustaining properties of highly stressed metal members such as drill steel, drill rods, drill pipes their connectors and attachments, and their welds, joints, fillets, threads and metallurgical notches comprises applying pressure at spaced-apart intervals over all or part of the surface of the member, at temperatures below the recrystallization temperature, to plastically deform the metal at spaced-apart portions of the member, into permanent grooves or depressions to a depth of between one thousandth and one sixteenth of an inch and leaving juxtaposed portions of metal of the member in its normal undeformed elastic form, thus creating in the member locked-in residual stresses to enable said member to resist fatigue, corrosion fatigue and fretting. Fig. 1 shows a member 1 provided with grooves 2 formed according to the invention to leave undeformed portions 3 of metal in its original elastic form and plastically deformed metal in areas A adjacent the grooves. Examples of groove patterns are shown in Figs. 2 to 6 and 8 and their cross-sections are shown in Figs. 9, 10 and 11. Apparatus for carrying out the invention is attachable to a lathe and comprises a base 18 (Fig. 12) and fixed and movable supports 19 and 20 respectively accommodating sleeves 22 within which are slidably mounted spring-loaded contoured rollers 27 which act on the workpiece 30. The rollers may have contours as shown in Figs. 12a to 12i. Alternatively, the rollers are hydraulically operated by pistons 34 (Fig. 13). Apparatus for treating the interior surfaces of hollow members, e.g. cylinders, hollow shafts, marine shafts, tubes, gun barrels, drill pipes are shown in Figs. 13a to 13d. The rollers 27 are carried either by a lazy tongs mechanism operated by adjustable spring pressure (Fig. 13a) or by hydraulically operated pistons 34 (Fig. 13b). In a modification (Fig. 14) the roller 37 is spring-loaded and the roller 38 is mounted on a support 39 the pressure being applied to the support through a lever 41 by a spring arrangement 42. The apparatus is mounted on a lathe having a driving head 43. In another embodiment (Fig. 16) the apparatus consists in a base 47 supporting a movable member 49 slidable in a support 48 said member carrying a roller 60 on an arm 51 and a spring- loaded sleeve 54 carrying a roller 56. When connecting a drill bit 67 to the treated end 63 of a drill rod 64 (Figs. 18 and 22) a metal thimble 66 is placed over the treated end to protect the grooves from fretting and corroding. Specification 785,534 is referred to.