锻造技术英文文献和中文翻译(4)

菜单

An upsetter arrangement with multiple side punches, which is essentially a mechanical press connected to a hydraulic system to combine the advantages of both — used successfully for warm forging of steel and features four plungers, 60 strokes per minute and 600-ton capacity.

A Japanese design of a triple-action press in which the upper rams and lower ram can be independently moved (hydraulically) and sequenced as desired.

A method of precision forging low-ductility materials, whereby the billet is forced by the punch through a guide into an interference fit with a container, which sets up a compressive stress field for better forgeability — speed and maintenance were cited as possible drawbacks.

A Japanese mechanical/hydraulic press using multiple coaxial rams, in which the central ram is driven mechanically and the surrounding rams are actuated hydraulically relative to the central ram. Addi- tional possibility involves the use of horizontal punches driven by hydraulic pressure with pro- grammed actuation.

United States design of an upsetter using multiple- piece split tooling to enable formation of a bulge in a shaft, with the tooling segments retractable during shaft ejection.

Russian design of a die set, possibly economical for forging chain sprockets in large lot sizes, featuring multiple side rams which are moved by a wedge action initiated by the main ram to penetrate the workpiece and form the teeth of the sprocket.

CAD/CAM IN CLOSED-DIE FORGING

Computer Aided Design/Computer Aided Manufacturing (CAD/CAM), as applied to the forging industry, involves forging design, preform design, and die design with the use of interactive computer graphics. In addition, NC tape can be generated to manufacture electrodes for use in subse- quent electrical discharge machining (EDM) of the die cavity. Similar output can also be obtained for NC milling of the die cavity.

There were four presentations which dealt with the appli- cation of CAD/CAM techniques to closed-die forging situ-

J. APPLIED METALWORKING

ations. The first of these presentations was by A.M. Sabroff of Eaton Corporation’s Manufacturing Services Center, who presented some of the results of a joint Eaton—Battelle study on applying CAD/CAM to precision-forged spiral bevel gears. Mr. Sabroff prefaced his talk with the remark that precision, automation, and CAD/CAM are three subjects

which, in his view, will determine the destiny of the fO*8‹•g industry. In its 15-year experience with precision forging, he

said, Eaton has pioneered in the precision forging of auto- motive and truck spur gears, as well as straight bevel gears for truck, off-highway, and agricultural vehicle applica- tions. All of Eaton’s straight bevel gears are now precision- forged, i . e . , be gear teeth, which constitute the functional surfaces of the pan, are forged to as-finished or pregrinding tolerances. The only machining requirement is on the back face and other reference surfaces of the gear. For spur gears, the traditional forging practice involved hot forging with multiple blows in a mechanical press, followed by nor- malizing and considerable machining all around. In con- trast, precision forging is carried out in the warm forging range of temperatures with a significantly reduced machin- ing envelope. Besides reducing the amount of machining, other advantages include materials and energy conservation, good surface finish, optimum microstructure, and better properties. Disadvantages appear to be costlier dies and the requirement for more stringent process control at every stage of the operation, which would have to be contrasted against specific advantages, on a part-by-part basis, to determine the overall economics.