41results about How to "Reduce residual tensile stress" patented technology

A glass laminate substrate for electronic substrates, such as flat panel displays, includes a transparent glass core bounded by transparent glass skin layers, wherein the coefficient of thermal expansion of the core is greater than the coefficient of thermal expansion of the skin layers thereby forming a residual compressive stress in the skin layers and a residual tensile stress in the core. The relative thickness of the skin layers can be selected to enhance the strength of the glass laminate substrate while maintaining a sufficiently low residual tensile stress in the core to allow scribing and separating of the substrate to size. Interlayers can be located between the core and the skin layers, wherein the interlayers include a residual compressive stress, and produce a reduced residual tensile stress in the core.

Improved shape and strength of the weld in a welded structure are obtained by use of a weldable aluminum product comprising a structural component which is a sheet, a plate or an extruded body and is made of an aluminum alloy containing not more than 1.5 wt % Zn. This component has, adhered on at least one side, a cladding layer made of an AA7xxx-series alloy having a corrosion potential lower than that of the alloy of the structural component. The alloy of the structural component is preferably an AA5xxx-series alloy containing Mg in the range 2 to 6 wt %.

The invention relates to the field of laser processing, and in particular relates to a method for reinforcement of metal surfaces by large area laser shock. The invention adopts laser shock reinforcement for interval shocks on the surface of a workpiece according to a certain trajectory, and large area lap connection shock on the workpiece can be achieved by multilayer stacking. The method can effectively reduce the residual tensile stress generated in the shock region boundary during the laser shock reinforcement, meanwhile avoids the absorption layer destruction and workpiece warpage, and can obtain a uniformly distributed shock reinforcement effect.

The invention relates to a laser welding method for ultrasonic vibration along with welding, and belongs to the field of welding. According to the method, preheating is applied in the welding process,and ultrasonic vibration is applied to the front side of a weld joint at a certain distance behind a molten pool; a corresponding relation exists between the preheating temperature T and the distanced from the top end of an ultrasonic head to the welding position, wherein the relation expression is as follows: T is equal to 30d-40, the unit T is DEG C, and the unit d is mm; and the position, thepower and the force of ultrasonic application are adjusted according to the mechanical property of materials under the preheating temperature. According to the laser welding method, the welding residual stress can be effectively reduced, pores and cracks are reduced, and thus the fatigue performance of the weld joint is improved, and the welding deformation is reduced. By adopting the method, thetemperature gradient in the cooling process can be effectively reduced, and the residual stress is reduced; and the plasticity of the ultrasonic application area can be improved, and the ultrasonic effect is better. The ultrasonic impact can effectively reduce residual stress, refine crystal grains and reduce pores and cracks, and thus the fatigue performance of the weld joint is improved; and the metal plastic extension of the weld joint can effectively reduce the welding deformation.

The invention relates to a micro rolling and ultrasonic-assisted laser cladding device, in particular to strengthening to the surface of a cladding layer. The device comprises a workbench, a fixed check block, a workpiece, a first mechanical arm, a synchronous powder feeder, a laser device, a micro roller, a rotating device, an amplitude-change pole, a second mechanical arm and an ultrasonic generator. During laser cladding, the micro rolling technology and the ultrasonic technology are used for assistance, and adverse effects left during pure laser scanning can be eliminated to the largest degree by means of the combination. By means of micro rolling, dendritic crystalline lenses generated during cooling of the cladding layer are ground through the micro roller, the crystal structure is refined, and air pores are effectively suppressed. By means of the ultrasonic technology, residual tension generated during temperature decrease of the cladding layer is eliminated, and cracks are effectively reduced. The micro rolling technology and the ultrasonic technology are applied to the laser cladding layer, and compactness, isotropy and other properties of the cladding layer are further improved.

The invention relates to a preparation method of a boron carbide ceramic composite material. The method includes the steps of S1, performing wet mixing on boron carbide powder, a carbon source and a mixing medium to obtain a mixed material, drying, grinding, and sieving to obtain a material for mould pressing; S2, performing compression molding on the material for mould pressing, and drying to obtain a ceramic green body; S3, placing a silicon block on the ceramic green body to perform vacuum infiltration reaction sintering so as to obtain a boron carbide ceramic composite material precursor;S4, removing the residual silicon on the surface of the boron carbide ceramic composite material precursor, performing thermal treatment on the precursor in heating equipment, and cooling to room temperature to obtain the boron carbide ceramic composite material. The preparation method can lower sintering temperature, increase the compactness of the boron carbide ceramic composite material and increase the mechanical performance of the boron carbide ceramic composite material.

There is provided a press forming method capable of suppressing a camber back, which occurs in a hat-shaped member while reducing a restriction on a shape of the hat-shaped member. At a time of the press forming, a blank material (4) in which a longitudinal line length is at least longer than a longitudinal line length of a top plate portion of a hat-shaped member (5) is fixed between a pair of press dies (lower die (2), upper die (3)), which have bent surfaces (convex surface (2a), concave surface (3a)), while being warped upward, that is, in a bending direction of the lower die (2) and the upper die (3). Subsequently, for the fixed blank material (4), a bent portion of the hat-shaped member (5) is press formed by using the convex surface (2a) and the concave surface (3a).

The invention provides a laser cladding process based on thermal aging treatment. The laser cladding process comprises the following steps of (1) pretreating a cladding part and a flat sample; (2) clamping the flat sample, and arranging a heating device below a chuck clamp; (3) arranging a temperature sensor near a to-be-cladded area of the flat sample for detecting the cladding temperature; (4) carrying out a single-pass laser cladding test on the flat sample, and recording the temperature range achieved by the cladding surface under corresponding cladding process parameters; (5) clamping the cladding part on the chuck clamp, enabling a temperature control system to control the heating temperature of the heating device according to the recorded temperature range, performing dynamic temperature control on the cladding part, and maintaining the overall temperature of the cladding part within the temperature interval achieved by laser cladding; (6) setting the corresponding laser cladding process parameters, and carrying out laser cladding on the surface of the cladding part; and (7) after the cladding is finished, controlling to stop heating by the temperature control system, and slowly cooling to room temperature. According to the process, the generation of cladding cracks can be reduced, and the cladding quality and effect can be improved.

The invention discloses a process for reducing the residual stress of a butt-welding seam of a dissimilar metal thick-wall barrel body, and belongs to the technical field of control over welding residual stress. The process for reducing the residual stress of the butt-welding seam of the dissimilar metal thick-wall barrel body comprises the following step: a pressing step of applying an axial pressure on the butt-welding seam between dissimilar metal workpieces, and enabling metal in a welding seam area to generate the plastic strain of transversal compression and radial extension, so that thewelding residual tensile stress of the welding seam and areas at the two sides of the welding seam is released. According to the process for reducing the residual stress of the butt-welding seam of the dissimilar metal thick-wall barrel body, by applying the axial pressure on the butt-welding seam of the dissimilar metal thick-wall barrel body, the residual tensile stress at the butt-welding seamof the dissimilar metal thick-wall barrel body can be effectively reduced.

The invention relates to the technical field of pipeline welding, and discloses a pipeline sleeve joint welding process. The process comprises the steps that S1, oil stains inside and outside the pipewall are removed; S2, peeling of the inner wall of the sleeve is removed; S3, the end of the pipeline is sleeved with a sleeve, and the gap between the sleeve and the pipeline is 2-3mm; S4, multi-layer welding is conducted on the gap between the pipeline and the sleeve to form multiple layers of welding seams coaxial with the pipeline; S5, after the multiple layers of welding seams are formed, acover surface layer is welded to the welding seams, and the cover surface layer covers the welding seams and the end of the pipeline; and S6, arc pits are filled with welding wires in the arc extinguishing process. The generation of a low-melting-point liquid film is prevented, the welding tensile stress is reduced, the permeation of harmful substances is controlled, the residual tensile stress after welding can be effectively attenuated through multiple layers of welding, the cooling speed is reduced, the generation of hot cracks is prevented, slow arc extinguishing is realized, and the arc pits are filled with the welding wires to further prevent the generation of the hot cracks.

The invention discloses a hot melt adhesive assisted laser shock peening method for a small hole of an aircraft structural part, and belongs to the technical field of laser shock peening. The method comprises the following steps: (1) mounting a workpiece with a small hole structure on a clamp, and pasting a sacrificial layer on one end surface; (2) the other end face faces upwards, liquid hot melt adhesive is injected, and after the hot melt adhesive is solidified, a sacrificial layer is pasted; (3) a restraint layer water film is applied to the to-be-strengthened area, laser shock strengthening is conducted on the two end faces of the small hole, and strengthening parameters are as follows: the laser energy is 5-10 J, the light spot diameter is 2-3 mm, the pulse width is 15-20 ns, the frequency is 1-5 Hz, the water film thickness is 1-2 mm, the lap joint rate is 25%-75%, and the shock frequency is 1-4 times; and (4) removing the sacrificial layer after the workpiece is subjected to laser shock peening, and removing the hot melt adhesive in the small hole by using a metal tool of which the diameter is smaller than that of the small hole. The method can ensure the strengthening effect of the laser shock peening small hole.

The invention improves a narrow-gap adjustable device and a cosmetic welding adjustable device for improving the bearing capacity of butt joints, which belong to the field of a welding technique and can acquire high-quality butt joints with good bearing capacity. A fastener is used for axially pressing and fixedly mounting a group of annular sheets with different thicknesses and two wheel rim bodies on a shaft sleeve; and the two wheel rim bodies and the group of annular sheets with different thicknesses between the two wheel rim bodies are arranged coaxially, and the surface profile of the integration of the wheel rim bodies and the annular sheets is matched with the surface shape of the weld reinforcement of the butt joints. The narrow-gap adjustable device is convenient in operation, and has the advantages of high efficiency, high adaptability and the like; and the device with the adjustability can shape the butt joints which have different thicknesses and are made of different materials during welding. Under the sequential action of the narrow-gap adjustable device and the cosmetic welding adjustable device, butt joints with less weld defects, fine grains, low welding residual stress, desired shape and size, and high bearing capacity can be manufactured.