Showing papers on "Peening published in 1982"

Apparatus for processing welded joint parts of pipes

Abstract: Tensile residual stress in an annular welded joint part joining the ends of unit pipes is mechanically removed by applying repeated hammering strokes against the inner surface of the pipes over the entire joint part, thereby to cause such part to undergo local plastic deformation The repeated hammering strokes, which have a peening effect, are applied by several automatically operating hammering devices mounted radially on a rotary head secured to and unitarily moving with a shaft which is driveable in rotation about its axis and in translation in its axial direction

Method for simultaneous peening and smoothing

Abstract: A method for simultaneously shot peening and smoothing includes use of relatively large, smooth, hard, spherical steel shot having a substantially uniform diameter in the range 1-2.5 mm. Titanium workpieces are provided in one step with a compressive stress layer of the order of 0.13 mm and a surface finish of better than 15×10 -6 inch AA, compared to conventional peened finishes of the order of 40×10 -6 inch AA. Surface finish and peening intensity are inter-related and dependent on shot diameter, mass, velocity, and energy within relatively small limits. The shot diameter is uniform within ±0.05 mm; the shot impact velocity is uniform within ±4 percent or less, in the range 1.4-12 m/s.

Shot Peening and Residual Stresses

Abstract: Shot peening is a widely used method to improve the behavior of materials as for instance fatigue behavior or corrosion resistance The improvement of fatigue behavior is for example a consequence of either the strain hardening of surface layers or of the compressive residual stresses in surface layers induced by shot peening or of both It depends upon the strength or hardness of the material and upon the geometry of the workpiece which of these influencing factors is the predominant one In a high strength material, or in any notched workpiece residual stresses have an appreciable effect on the fatigue behavior and compressive residual stresses can enhance the fatigue strength (1,15,16)

The Mechanics of Some Industrial Pressing, Rolling, and Forging Processes

Abstract: Summary For the following little-researched industrial plastic metal-forming processes, brief descriptions are outlined and short accounts of the mechanics of important aspects of them are presented: the pressing of plate in circular or spherical dies, curved plate forming by peening or rolling, ring rolling, rotary forging, ball forming by forging, rolling, or the use of a shot-tower, and sheet perforation or neck extruding. These operations are chosen as being complex and to indicate some likely practical outlets for plasticity theory. For all of them the plastic deformation encountered is described. Results for machine or tool loads and torque are referred to and some discussion of processing defects is presented. Elastic springback in pressed plates is considered especially.

Separating and feeding system for a shot peening machine

Abstract: A separating and feeding system for a shot peening machine is of the type which includes blast wheels mounted on a housing of the machine and capable of propelling a plurality of shot generally downwardly into a critical blast region within the housing for shot peening a plurality of springs passing therethrough. The springs are supported on and separately conveyed along a pair of spaced spinner rolls along a peening path into one side of and through the critical blast region. The separating and feeding system includes an entrance chamber within the housing adjacent the one side of the critical blast region. An elongated horizontally extending chain is mounted relative to the housing for continuous movement from a first end exterior of the housing through an opening in a wall of the housing to a second end within the entrance chamber at the one side of the critical blast region. The horizontally extending chain supports the springs thereon and makes frictional contact therewith to transport the springs from the one end to the second end. The chain is capable of continued movement beneath any of the springs which are prevented by retarding gates from continuing transportation. A shot screening and spring stopping gate is in a normally closed position at the opening to prevent escape of shot therethrough and entrance of one of the springs into the entrance chamber. When there is no spring at the one side of the critical blast region, a signal is provided for opening the shot screening and spring stopping gate for a predetermined amount of time to allow the chain to transport the one spring to the critical blast region.

Apparatus for processing welds of pipes

Abstract: Tensile residual stress in an annular welded joint part (2) joining the ends of unit pipes (1) is mechanically removed by applying repeated hammering strokes against the inner surface of the pipes over the entire joint part thereby to cause this part to undergo locally plastic deformation. The repeated hammering strokes, which have a peening effect, are applied by several automatically operating hammering devices (21) mounted radially on a rotary head (18) secured to and unitarily moving with a shaft (6) which is driveable in rotation about its axis and in translation in its axial direction.

Reinforcing method of spring steel

Abstract: PURPOSE:To obtain spring steel which is increased in strength by tempering the spring steel which is subjected to a hardening treatment in a prescribed temp range, tempering the same in the temp region where the change in the 3rd stage arises or the temp below said region and subjecting the steel to shot peening simultaneously in the tempering process CONSTITUTION:Electricity is conducted through electrodes 2, 3 to the spring steel A which is subjected beforehand to coiling and a hardening treatment to heat the steel quickly in a short time, for example, for about 30sec, and the steel is tempered at the temp at which the change in the 3rd stage of the tempering arises or the temp below said temp The temp in this case is <=350 degC, more preferably about 200-250 degC with middle carbon steel The heating speed, heating temp, holding time, etc in this stage are controlled with a computer 3 for control in accordance with the surface temp of the steel A while aid temp is detected with a temp measuring device 4 Shot peening devices 5, 5 are operated simultaneously in the above-described tempering stage to apply warm peening to the steel with the prescribed coverage, arc height and projection time controlled with the computer 3, whereby the intended spring steel is obtained

Method and apparatus for shot peening of curved pipe

Abstract: PURPOSE:To prevent lowering of peening effect by dividing all nozzles to a plural number of nozzle groups, alternately using the nozzle groups and preventing mutual interference by the nozzles at the time of shot peening to eliminate residual tensile stress of outer face of a curved pipe CONSTITUTION:Nozzle covers 1 and 2 are swivelled driven by a motor (M) for the first semicircle from (C1) to (C3) through (C2) along a curved pipe 9 When the nozzle covers are swivelled, pulverized material is concentrically sprayed on an upper side (A1) and inner side (A2) only by the first nozzle group consisting of nozzles N1 and N2 of the curved pipe 9 and then discharged outside from discharge ports (E3) and (E4) When shot peening of one side of the curved pipe is processed in this way, the nozzle covers 1 and 2 are reversed from (C3) to (C1) through (C2) and when they are swivelled for the next semicircle, the first nozzle groups (N1) and (N2) are stopped, pulverized material is sprayed from the second nozzle groups (N3) and (N4) and shot peening of a lower side (A3) and an outer side (A4) of the curved pipe 9 is processed After that, pulverized material is discharged from separate ports (E1) and (E2)

Effects of Multiple Shot-Peening/Cadmium-Plating Cycles on High-Strength Steel

Abstract: A study was made of the effects of multiple shot-peening and cadmium plating operations on high-strength AISI 4340 steel used in aircraft landing-gear applications. No detrimental effects were observed on surface microstructure and tensile properties or on fatigue and unnotched stress corrosion resistance in high-humidity air. An apparent degradation in stress corrosion life of fatigue precracked specimens was observed after four and five peening and plating operations.

Shot peening method for gear

Abstract: PURPOSE:To treat each tooth surface and each bottom land of a gear uniformly by shot peening, by a method wherein a gear is revolved around a table while being rotated about its own axis on the table during the tooth surface shot peening treatment. CONSTITUTION:A strut 11 is built at a removably supporting part 5 on the table 6 in a set position A, then masking members and the gears 2 to be treated are alternately fitted to the strut 11 to form stacks 14 having the tooth parts on the upper side and the seat faces on the lower side, and a sleeve and a top plate are fitted respectively to the strut 11 at the top. The stack 14 is then transferred to a peening position B by rotating the table 6 by 180 deg.. At the peening position, the stack 14 is revolved along a revolution track by a fine movement means for the table while being rotated about its own axis by a rotating means 17. Accordingly, the surfaces to be treated (tooth surfaces and bottom land surfaces) of the gears 2 are uniformly shot peened by shots 8, 8... jetted from the an impeller 7.

Fatigue of Thick Tubes: Effect of Mean Pressure, Honing, Plating, Burnishing, and Peening

Abstract: Experimental results are presented for fatigue of closed-ended thick-walled tubes of 2.5 wall ratio and 32.3 mm (1.27 in.) ID for SAE 4333 steel subjected to pulsating internal pressure. Results are given for the following conditions: as-received-polished bore, stress relieved, honed with a 207 MPa (30 ksi) mean pressure, honed with a 276 MPa (40 ksi) mean pressure, nickel plated bore, roller burnished bore, and shot peened bore.

Shot Peening and Valve Fatigue

Abstract: Robert Dusil UDDEHOLM Strip Steel AB S-684 01 Munkfors, Sweden Lars-Ake Norstrom Steel Research Center, UDDEHOLM AB S-683 01 Hagfors, Sweden Shot peening can be used as one of the finishing operations in manufacturing of compressor valves. During this process, a material deformation hardening on the surfaces is reached and the induced residual stresses are generally considered as beneficial with respect to the fatigue life. A study was made to evaluate the influence of the shot peening on the valve material fatigue. The fatigue data are presented in view of the surface and subsurface residual stresses, their relaxation during dynamic loading and the resulting surface topography for two standard valve steels AISI 1095 (1 % C) and AISI 420 (0.38 % C, 13.5 % Cr, 1 % Mo) .. Some practical hints on the relevance of the shot peening treatment for high strength valve steels are given. INTRODUCTION Tbe development efforts a~m~ng at increased fatigue performance of compressor valves include besides design aspects such as modification of the valve lift, valve speed, improved cushion at guard or seat (1-4), also materials and valve treatment (5, 6). Shot peening is one of the well known finishing techniques applicated in cases when the machine component containes geometrical notches or other stress raisers. There is experimental and empirical evidence showing improvement in fatigue durability of components such as gears,shafts etc, fabricated from low strength or medium strength materials with UTS below 1400 MPa (200 ksi) (7). The effect of the shot peening on thin valves and reeds from high strength materials with UTS above 1800 MPa (260 ksi) is, however, more unclear particularly at high cycle fatigue above 106 loading cycles and high loading rates. Furthermore, there are also significant costs involved in valve finishing by peening technique. The aim of this work was to contribute to the basic understanding of the effect of shot peening of the fatigue behaviour of valve steels. 105 Borje Johansson Steel Research Center, UDDEHOLM AB S-683 01 Hagfors, Sweden John M Thullen DE-STA-CO Division, Dover Corp. Detroit, MI, 482 03 MATERIALS Two standard steels, UHB 20C and UHB Stainless 716, strip thickness 0.38 mm (0.015 in) were used. Both materials were cold rolled, hardened and tempered. The material data are presented below: Chemical composition (wt %) Grade UHB C Si 20C 1.0 0.3 Stainless 716 0.38 0.5 Mn Cr Mo