Showing papers on "Peening published in 1985"

Method and apparatus for imparting a simple contour to a workpiece

Abstract: An improved method and apparatus is provided for imparting a simple contour to an aircraft skin. A treatment chamber having a conveyor with a workpiece attached thereto and a shot peening blast unit positioned therein is provided. The workpiece is conveyed past the blast unit for peening treatment. A control system is provided for orienting the workpiece and blast unit so that the peening is done only in narrow spanwise strips and only on common chord percentage lines of the workpiece. This method and apparatus thereby creates chordwise simple curvature to the workpiece while minimizing compound curvature effects.

Electromagnetically operated peening tool

Abstract: Work piece surfaces are peened by electromagetically controlled steel nees which are guided for back and forth sliding movement in a guide plate. Each needle has its own electrically controllable drive magnet. All the magnets are energized in a controlled sequence by a control unit which energizes the drive magnets in a given sequence or pattern and in accordance with adjustable parameters such as the stroke amplitude and frequency of each needle stroke. Thus, the work piece may be deformed into a particular shape and/or its surface may be work hardened or densified and areas of different surface stress may be produced in the work piece surface. Work pieces may be shaped into any desired three-dimensional curvature.

Shot peening machine

Abstract: An improved shot peening machine is of the type which includes blast wheels capable of propelling a plurality of shot generally downwardly into a critical blast region of the machine for shot peening a plurality of springs passing therethrough. The improvement includes a housing for the machine including a blast cabinet, an entrance chamber and an exit chamber. The blast cabinet generally defines the critical blast region. Horizontally extending spinner rolls for the springs extend through the blast cabinet and terminate at a first end at a first edge of the critical blast region within the entrance chamber and a second end at a second edge of the critical blast region within the exit chamber. The springs are conveyed along a peening path on the spinner rolls from the first end to the second end thereof. A feeding system feeds the springs from an exterior of the housing into the entrance chamber to supply the springs to the first end of the spinner rolls. A discharge system discharges the springs from the exit chamber to the exterior of the housing as the springs are conveyed from the second end of the spinner rolls.

Process for producing permanent magnets and permanent magnet

Abstract: Fe-B-R type permanent magnet is produced by: forming an anticorrosive coating film layer on a Fe-B-R base permanent magnet material body by means of vapor deposition to thereby improve the corrosion resistance thereof. The anticorrosive thin film is formed of metal, oxides, nitrides, carbides, borides, silicides, composite compositions thereof, or a mixture thereof. Additionally shot biasting, peening, heat treatment for forming an interdiffusion layer, and/or resin impregnation may be applied.

Preventing stress corrosion cracking of bearings

Abstract: A method of inhibiting stress corrosion cracking of a bearing 10 of the type installed on a shaft with an interference fit. The surface of the inner ring 16 is shot peened at least at and near the junctures 28,30 of the endwalls 22,24 with cylindrical inner surface 26. The shot peening is performed with sufficient intensity to produce residual compressive stress which offsets at least a portion of the tensile stress resulting from the installation interference fit. The shot peened surface is then coated with a thin metallic material. Finally, the inner bearing ring 16 is baked to remove hydrogen resulting from the coating.

Conveyor system for a shot peening machine

Abstract: A conveyor system is for a shot peening machine of the type which includes blast wheels which are capable of propelling shot generally downwardly into a critical blast region for shot peening a plurality of springs passing therethrough. The springs are supported on horizontally extending spinner rolls within the critical blast region to be capable of being conveyed along a horizontal peening path therethrough. The conveyor system includes a plurality of finger elements extending horizontally into the critical blast region above the spinner rolls and transversely of the peening path. Each finger element includes a first end for making contact with one of the springs and a second end which is secured to and supported by a continuous chain located remotely of the critical blast region. The finger elements are mounted on the chain a predetermined distance apart to be capable of receiving a single spring therebetween. The continuous chain is mounted in a horizontal loop between an idler sprocket and a driving sprocket to advance each finger element and cause it to be extended into the peening path to convey one of the springs therewith through the critical blast region. Each finger element will extend through and be advanced along a horizontally extending slot in a wall separating the critical blast region from the continuous chain.

Manufacture of bearing

Abstract: A process is described for the production of bearings for sustaining high loads, the bearings having indentations (14, 32) filled with soft overlay alloy (13, 33). The indentations are produced by peening or embossing. The peening is preferably performed with rounded ceramic shot of 0.25 to 0.5mm diameter. Indentations should preferably be between 0.01 and 0.05mm deep. In one embodiment a bearing is described having alloy comprising a steel-backed (10) aluminium-based bearing alloy (11) having a composition of, for example, Al-Sn20-Cul and a soft Pb-SnlO overlay (13) there also being an interlayer of 3 to 5 um of nickel (12) between the bearing alloy and the overlay. Bearing surfaces having a continuous overlay or a composite surface comprising randomly-shaped areas of bearing alloy and overlay may be produced.

Some considerations in surface treatment of outdoor metal sculptures

Abstract: Air-abrasive methods have been used for the cleaning of outdoor metal sculpture for the past 11 years. The best known method among these is glass shot-bead peening. Other air-driven abrasives, such as walnut shells, offer an alternative which is gentler and different in action. Many of the fundamental ideas surrounding the various air-abrasive methods have not been rigorously examined. These include assertions that the methods do not remove any metal, that they passivate the surface by peening, that they reduce the corrosion rate, that it is necessary to remove all the corrosion products from the surface before applying a protective coating, and that the methods do not alter the aesthetic appearance of the surface. These assumptions will be examined both on theoretical and practical grounds using such methods as the scanning electron microscope, corrosion rate measurements, and a review of the literature on erosion by small, high-velocity particles, which is as yet poorly known to the conservation community. The authors illustrate the differences between abrasives and show that a fundamental understanding of the physical and chemical processes involved is necessary for their appropriate application.

Shot blast device for peening coil spring

Abstract: PURPOSE:To improve the whole effect of peening of a coil spring, by forming a line never containing respectively exceeding a fixed proportion a shot of small grain size to be mixed with that of large grain size in the first shot chamber while a shot of large grain size to be mixed with that of small grain size in the second shot chamber, individually provided. CONSTITUTION:A shot device 13 is charged with a shot of large size, and the shot decreasing its size due to circulative use and a shot of small size or the like leaking from a seal part are attracted to a chamber 12 by an air flow by a dust collector device communicating with the chamber 12 and stalled, falling down to a vibrative screen device 23 and returning to a shot chamber 2 through a screening net 23b. Next, a shot of small size shot from a shot device 24 reaches a shot tank 18, and the vibrative screen device 23, to which some of the shots of small size mixed with the shot of large size are conveyed, returns only the shot of small size passing through the screening net 23b to the second shot chamber 2. Further the second shot chamber 2 never mixes the shot of large size to a proportion above the fixed value by returning the shot of large size, slipped falling onto the screening net 23b, to the first shot chamber 1 to be reused. In this way, a shot blast device increases an arc height value by the shot of large size while a coverage value by the shot of small size.

Improvement of fatigue strength of Al alloy welded joints by toe-peening.

Abstract: In order to improve fatigue strength of Al alloy welded joints, the effects of grinding on weld reinforcements and toe-peening on weld toe lines were investigated. Fatigue tests were carried out on three series of A5083 Al alloy butt welded joints and A7N01 Al alloy cruciform welded joints. Fatigue strength of the treated joints were compared with thatof as welded ones.Following results were obtained;(1) Toe grinding and reinforcement removal grinding increased the fatigue limits of the butt welded joints by 59% and 120%, respectively.(2) The fatigue limit of the peened joints was about 80-120% higher than that of as welded joints.(3) The fatigue strength of the joints, thermally stress relieved after peening, was equal to that of as welded joints.(4) The effect of the fatigue strength improvement can be attributed to compressive residual stress generated by toe-peening.

Spindle for rotopeening apparatus

Abstract: A rigid peening spindle for rotopeening the inside wall of a tube is disclosed herein. Generally, the peening spindle comprises a rotatable housing insertable within a tube, a mandrel disposed within the housing and having a plurality of peening flappers connected thereto, and a pair of bearings for rotatably mounting the mandrel within the housing in an off-center orientation relative to the longitudinal axis of the housing so that the peening flappers rotate and orbit within the tube when the mandrel and housing are simultaneously rotated. The housing includes a cage formed from an open section and a ligment, and the mandrel is rotatably mounted within the housing so that the peening flappers may engage the inside wall of the tube through the open section of the cage. Finally, each of the bearings which rotatably mount the mandrel in an off-center manner preferably have an outer diameter slightly larger than the outer diameter of the housing so that they may engage the inside wall of the tube in a running engagement within fairly tight tolerances, and thereby control the stand-off distance between the peening flappers and the inside wall of the tube. The bearings are preferably made from a self-lubricating plastic material. The invention is particularly useful in rotopeening the interior walls of the heat exchange tubes of a nuclear steam generator in order to prevent stress corrosion cracking in the tubes.

Method for working surface of cast steel

Abstract: PURPOSE:To vanish fine vacancies present on the surface of cast steel and to improve the corrosion resistance by subjecting only the surface layer of the cast steel to impactful compressive plastic deformation and by heating the cast steel to the diffusion temp. or above. CONSTITUTION:The surface of cast steel is peened to cause plastic deformation to an extent exceeding the size of fine vacancies present on the surface. The cast steel is then heat treated at >=1,000 deg.C diffusion temp. for >=1hr. By this surface working method, fine vacancies present on the surface of the cast steel and just under the surface are vanished, and the corrosion resistance is improved.

Multi-spindle rotopeening apparatus

Abstract: A rotopeening apparatus comprising a plurality of peening spindles, a rotary and orbital drive assembly coupled to the spindles, and an oscillatory drive means for reciprocating the spindles within the interior of an array of tubes is disclosed herein. Each peening spindle includes a rotatable mandrel connected to at least one peening flapper, as well as means for orbiting the mandrel peening flapper around the longitudinal axis of the tube. The rotary and orbital drive assembly includes an orbital driveshaft and a rotary driveshaft which are concentrically disposed with respect to one another and are detachably connectable to the rotatable and orbital mandrel of the peening spindle. Finally, the oscillatory drive assembly includes a frame having a translatable saddle plate for carrying and moving the rotary and orbital drive assembly within the frame, and four threaded rods journalled within the frame and coupled to a reversible motor which are screwed through nut assemblies fixed onto the corners of the saddle plate. As the reversible motor simultaneously rotates the threaded rods, the saddle plate translates and reciprocates the peening spindle detachably connected to the rotary and orbital drive assembly in "riding nut" fashion. The apparatus is particularly useful in simultaneously rotopeening a plurality of heat exchange tubes mounted within the tubesheet of a nuclear steam generator.

Surface treatment of metal by shot peeling

Abstract: PURPOSE:To generate a stress peening effect and to improve the fatigue fracture strength of the treated surface by setting the surface of a metallic material to lower temp. than the inner part in shot peening treatment of said surface. CONSTITUTION:Small grains of steel bass or cut wires, etc. are blown at high speed to the surface of the metallic material to perform the shot peening treatment. In this case, the temp. of material is held between 50 deg.C and about 300 deg.C, and the temp. of the surface to be treated set to lower temp. then that of the inner part. Or the temp. of the shot to be used is set to lower temp. than that of the treating metal so that the shot grains take the heat off the treating surface and makes it low temp. when said grains impinge thereto. So-called stress peening treatment is performed under the state in which tensile stress is caused due to such temp. difference at the surface of the treating metal, the surface is hardened, residual compressive stress is caused, and the fatigue fracture strength is improved remarkably.

On the relation between peening condition and fatigue strength.

Abstract: Several experiments were run to determine the relations between shot peening conditions and fatigue strength. Shot peening was performed for carbon steel (0.45%C). The influences of the factors such as surface residual stress, work hardened layer and surface roughness on peening effect are cleared. Surface residual stress was measured by X-ray diffraction method. The results obtained from experiment are as follows : (1) Shot peening improves fatigue strength from thirty percent area coverage. (2) The more the kinetic energy of a shot, the more the fatigue strength neverthless surface residual stress does not so change, except for thin work- piece. (3) Removing the surface roughness produced by shot peening, the peening effect on the fatigue strength increases. (4) The maximum peening effect on the fatigue strength and life was about 13% and 820% respectively.

Correcting device of peening flaw in gear tooth surface

Abstract: PURPOSE:To enable a peening flaw in a tooth surface to be surely corrected, by energizing a gear-shaped grinding tool, having only a tooth flank aligning a pitch circle and an external diameter surface, with a gear to be cut so that said engaged pitch circle comes to be in a tooth flank part of the gear to be cut CONSTITUTION:A correcting device engages helical gears 27, 28 of a cutting tool 11 with a helical gear 7 of a gear to be cut 5 so that an engaged pitch circle comes to be in a tooth flank of the gear to be cut 5 Under this condition, the cutting tool 11 is rotated to be driven by driving the gear to be cut 5 to be rotated, and the device, grinding a tooth surface of the helical gear 7 in the gear to be cut 5 by meshing the both tool 11 and the gear 5, removes a protrusion due to a peening flaw Said cutting tool 11, coating a tooth surface of the helical gears 27, 28 with diamond or a CBN sintered carbide quality alloy by electrodeposition, forms a tooth only to the tooth flank on the basis of an involute curve further with the pitch circle agreeing with an external diameter surface, and the tool 11 is brought into slide contact over the whole region because the engaged pitch circle comes to be in the tooth flank part of the gear to be cut 5 In this way, the peening flaw can be surely corrected

Improvement in the Fatigue Behavior of Tank Track Pins

Abstract: : This investigation is aimed at improving the fatigue behavior of tank track pins through the use of better processing methods and materials. Five different compositions of steels investigated: SAE 865OH, 4340, 4140, 8620 and 1045. These were subjected to the following treatments: induction hardening, stress shot peening, nitriding and carburizing. All steels except 1045, received final treatment of shot peening. Tension-tension bending fatigue tests were conducted on these pins to determine the S-N curve of each type of steel and the result compared with the data on the regular production tank tack pins obtained in another investigation. Stress shot peened 865OH pins have the highest residual compressive stress of -175 ksi on the surface and demonstrate the best fatigue limit of 198 ksi. The induction hardened, nitrided and carburized 4340, 4140, and 8620 steel pins, which have been shot peened, have a surface hardness range of Rc 58 -62 and shown an equal level of compressive residual stress of about -110 ksi on the surface. Carburized 8620 pins demonstrate the second highest fatigue limit of 175 ksi followed in turn by induction hardened and stress shot peened 4340, induction hardened and nitrided 4140 and carburized 1045 with the lowest fatigue strength.