Abstract: A magnetic generating device was proposed to regulate the transverse and backward flow of weld pool for high-speed gas metal arc welding (GMAW). Compound external magnetic field (EMF) was simulated to verify the feasibility of designed magnetic generating device. The highest welding speed with good weld bead appearance was 1.7 m/min with the wire feed speed of 9.0 m/min when compound EMF was applied. The effect of the compound EMF on the arc and droplet motion was studied by image acquisition system. The suppression mechanism of the compound EMF on the undercut defect of high-speed GMAW was analyzed. The mechanism of the influence of the applied compound EMF on different welding speeds and welding currents was studied by the application of the compound EMF-assisted welding process, and low-cost, high-quality, and high-speed welding technology was realized.

Abstract: This article presents a bonded dual-component microstructured planar device made of acrylic glass for vertical light emission. It features optical, cone-like undercut microstructures for efficient illumination from a light guiding plate. This microstructured light guide is designed with the help of numerical raytracing simulations for the use as an innovative luminaire for room lighting. It can also find application in display technology for efficient backlight units. To realize such undercut microstructures in acrylic glass, a variothermal injection molding process, complemented by an ultraviolet radiation assisted thermal bonding procedure is introduced. By modifying the glass transition temperature of a thin surface layer of the microstructures the undercut microstructures can be bonded thermally to a light guiding plate without any glue or solvent, while the shape of the microstructures is perfectly preserved. Measurements verify the high bonding quality and confirm the good correspondence between measured light emission and ideal optical simulations.

Abstract: We have novelly, to the best of our knowledge, developed the liquid flow microetching method that can treat a single microdisk in a microregion with precise position control for inkjet-printed microdisk lasers. The injection-drain wet etching setup consisted of two microneedles that successfully performed a formation of a fine undercut structure of an inkjet-printed microdisk on a pre-pedestal layer through the individual wet etching process. Then measurement of the undercut structure using scanning electron microscopy and lasing characteristics with whispering gallery modes were carried out to demonstrate performance of the etched microdisks. The measured lasing threshold decreased by half compared with that of the unetched microdisk directly printed on a fluorine-type film. A point to note is that this etching method exhibits an excellent undercut and lasing characteristics even when using a clad pre-pedestal layer having a refractive index higher than that of core microdisks. This technique, combined with inkjet printing, offers a powerful tool for individually designing a microdisk and can help develop novel devices that comprise several inkjet-printed microdisks being evanescently coupled.

Abstract: The ultimate behavior and bearing capacity of undercut fasteners installed in heat-damaged concrete are investigated in this paper in which the results of a rather comprehensive research pr...

Abstract: Provided by an embodiment of the present invention are 3D forming film manufacturing equipment and a method thereof. The present invention: performs molding with a uniform pressure by using a volume variable and thus, enables undercut part molding; improves the quality of a 3D molded forming film by reducing the thickness deviation of a forming film; and is able to identify an unauthorized forming film or molding when an unauthorized forming film or molding is used. According to an embodiment of the present invention, the 3D forming film manufacturing equipment having a mold identification function includes: a mold which molds a forming film and has a marked unit formed in a plurality of irregularities at one part; a press head unit which is positioned to correspond to the mold and has a variable distance from the mold; a volume variable body which is coupled to the press head unit, has elasticity such that a volume of the volume variable varies due to the inflow and outflow of liquid by the press head unit, and changes a volume to be in contact with the forming film positioned on the mold and thus, add pressure on the forming film, thereby allowing a forming film to be molded in a 3D shape; and a mold identification unit which irradiates a laser on the marked unit and collects the reflected laser to perform analysis on the marked unit.

Abstract: Micro texturing with dimples is one of the most established methods for the enhancement of lubrication and tribological performance. In this work, a novel approach of through-mask electrochemical micromachining is instigated to fabricate high-aspect-ratio circular micro-dimples utilizing a low-cost photoresist (AZ-4903) as mask. Experiments were performed to understand the influence of the applied voltage along with the electrolyte type and concentration on the machining precision and surface characteristics of the generated micro array. The influence of three electrolytes has been studied and it has been experimentally established that 10% NaCl + 10% NaNO3 is favorable during maximization of the depth of the generated micro-dimples to 39.03 µm whereas undercut is minimized to 15.15 µm by utilizing 20% NaNO3. The surface quality of the generated micro-dimples has been found to be the finest, i.e. 0.062 µm, for the samples machined with 10% NaNO3. Patterned arrays containing micro-dimples having maximum depths of 30 μm, 35 μm, and 40 μm were successfully fabricated over a stainless steel (SS304) substrate by using these electrolytes with considerable accuracy and repeatability. The experiments confirm possibility to obtain high-aspect-ratio micro-dimples with the least degree of undercut using this technique. Further, friction test results were analyzed to figure out the alterations in the frictional coefficient of the micro-dimples with different depths as well as with non-dimpled samples.

Abstract: We proposed a method for measuring undercut etching based on contact resonance atomic force microscopy (CR-AFM). Suspended undercut structures were fabricated through isotropic wet etching on a patterned SiNx/Si architecture. The materials beneath the SiNx masks with circular and rectangular shapes were partially etched to form center-supported thin plates. A clear contrast was observed between the supported and suspended regions by CR-AFM amplitude imaging, enabling accurate determination of the undercut boundary and the corresponding etched length. CR-spectroscopy measurements of the undercut dimensions were also applied by acquiring the contact stiffness distribution and by further fitting with models of analyzing the plate deflection. The etching rates given by both the imaging and spectroscopy measurements were in close accordance. The theoretical measurement error induced by finite CR-frequency to stiffness sensitivity was evaluated to be around 5% under our experimental settings. This work paves the way for in situ and real-time detection of undercut etching at the nanoscale and benefits relevant micro- and nano-fabrications.

Abstract: The self-piercing riveting process of 6016 aluminum alloy with 1 mm thickness and DC03 structural steel with 15 mm thickness was studied, the process of self-piercing riveting of dissimilar materials between 6016 aluminum alloy and DC03 steel plate is simulated based on DEFORM-2D, and the riveting experiments of plates at different placement sequence are carried out by using flat bottom die The results show that when 6016 aluminum alloy sheet is placed in the upper layer, the forming quality of self-piercing riveting is better The experimental values of undercut, head height and residual thickness are 0585 mm, 0069 mm and 0212 mm respectively The relative errors between experimental values and simulation values are 362%, 781% and 242% respectively, and the correctness of the finite element simulation is verified In addition, the relationship between undercut and die parameters of self-piercing riveting for steel-aluminum dissimilar materials is analyzed, and it is found that undercut increases with the increase of die width, while it decreases with the increase of die depth

Abstract: Modern quality management systems for welding products are based on procedures to minimize the likelihood of typical defects. The reasons for deviations of the energy parameters of the welding process include disturbances along the length of the arc or its breaks associated with a spasmodic change in the electrode wire feed speed, violation of the power circuit with the welded product, mains voltage, and shielding gas consumption. To establish a connection between deviations of the welding parameters with the quality indicators of the welded joints, a model for the formation of a weld seam under the conditions of technological disturbances has been developed. It is shown that the formation of the crater depends not only on the duration of the arc break, but also on the welding parameters. It has been established that in the presence of lateral oscillation of the electrode, an arc break significantly increases the undercut, the maximum depth of which movesto the center of the groove to the cutting center as the break duration increases. Whereas an increase in the amplitude of lateral oscillation of the electrode causes a significant increase in the depth of the crater.

Abstract: Considering the coupling of a droplet, keyhole, and molten pool, a three-dimensional transient model for the full penetration laser + metal inert gas (MIG) hybrid welding of thin copper alloy plate was established, which is able to simulate the temperature and velocity fields, keyhole behavior, and generation of the welding defect. Based on the experimental and simulation results, the weld formation mechanism for the hybrid butt welding of a 2 mm-thick copper alloy plate was comparatively studied in terms of the fluid dynamic feature of the melt pool. For single laser welding, the dynamic behavior of liquid metal near the rear keyhole wall is complex, and the keyhole has a relatively drastic fluctuation. An obvious spattering phenomenon occurs at the workpiece backside. Meanwhile, the underfill (or undercut) defect is formed at both the top and bottom surfaces of the final weld bead, and the recoil pressure is identified as the main factor. In hybrid welding, a downward fluid flow is strengthened on the rear keyhole wall, and the stability of the keyhole root is enhanced greatly. There are large and small clockwise vortexes emerging in the upper and lower parts of the molten pool, respectively. A relatively stable metal bulge can be produced at the weld pool backside. The formation defects are suppressed effectively, increasing the reliability of full penetration butt welding of the thin copper alloy plate.

Abstract: A technology called self-aligned selective undercut dry etching processing has been demonstrated for fabricating a highly efficient hybrid optical spot size converter (SSC) on a Si-on-insulator (SOI) template The process was based on a bonded wafer between the upper InP-based multiple quantum well heterostructure and the lower SOI substrate After defining the mask on the upper InP-based ridge waveguide, CF4/O2 dry reactive ion etching was then used for selective undercut etching of the Si material from the surrounding materials, forming a vertical waveguide coupler of the optical SSC The lower waveguide, whose dimension is even smaller than the upper one, can thus be vertically self-aligned to the top ridge via an independent processing step A laterally tapered waveguide ranging from 03 to 3 µm in width on the upper InP waveguide was fabricated The phase-matching condition of the vertical coupler leads to a length of 45 µm and extracts 88% conversion efficiency The selective undercut etching processing in III-V/SOI material provides a vertical self-alignment scheme for realizing compact and submicron scale heterogeneous integration in a Si photonics template

Abstract: The embodiment of the invention provides an OLED display panel, a preparation method thereof and an OLED display device. The OLED display panel comprises a special-shaped cutting area and a display area, the display area is arranged around the special-shaped cutting area, and the display area comprises an effective display area, a first packaging area and a second packaging area, and the first packaging area and the second packaging area are located between the effective display area and the special-shaped cutting area; wherein a stress buffer component is arranged in a concave corner at the undercut in the second packaging area; through arranging the stress buffer components in the concave corners at the undercut positions, stress in the concave corners is eliminated, breakage in the undercut positions is avoided, and the technical problem that an existing OLED display panel fails due to the fact that the concave corners at the undercut positions are prone to breakage is solved.

Abstract: A method of forming a gate structure with an undercut region includes, among other things, forming a plurality of fins above a substrate and an isolation structure above the substrate and between the plurality of fins, forming a placeholder gate structure above the plurality of fins in a first region and above the isolation structure in a second region, selectively removing a portion of the placeholder structure in the second region to define an undercut recess, forming a spacer structure adjacent the sacrificial gate structure, forming a dielectric layer adjacent the spacer structure and in the undercut recess, removing remaining portions of the placeholder gate structure to define a gate cavity, and forming a replacement gate structure in the gate cavity.

Abstract: In this paper, the stress intensity factor (SIF) expression for defected butt welds containing undercut and inclined lack of penetration (LOP) subject to far-field tensile stress is derived. Some of the standards such as ISO 5817 and BS EN 25817 have specified allowable limits for the length of the undercut and LOP defects and for the height of the weld. In addition, EN 29692 standard has determined an acceptable range for the groove angle. In this paper, the effect of these acceptable geometries on stress intensity factor (SIF) of butt welded joint is investigated through following steps: i) elastic analyses to predict crack tip stress intensity (KI, KII) and shape factors, ii) approximation of shape factors by Response Surface Method (RSM). These expressions provide design guidelines for welded butt joint containing unavoidable undercut and inclined lack of penetration (LOP) defects.

Abstract: The invention discloses a method used for air conditioner compressor shell straight seam welding. The method is mainly used for solving the welding quality problems of welding straight seam cracking and air holes, undercut, incomplete welding, weld beading and the like of a welding joint of an existing air conditioner compressor shell. The method used for air conditioner compressor shell straightseam welding comprises the steps of firstly, cleaning a surface to be welded of a steel plate; secondly, preparing an air conditioner compressor shell workblank; and thirdly, welding the air conditioner compressor shell workblank, welding the abut-joint straight seam of a rolled steel plate, adopting the plasma welding process, enabling an electric arc enter to right face the centre of the abut-joint straight seam, controlling a welding gun to move along the welding joint center for welding, during welding, enable the inclination angle between the welding gun and the forward horizontal direction of welding is 80 to 85 degrees, and in the welding process, adopting gas protection in the front face of the welding seam, wherein protection gas is Ar gas, and the gas purity is 99.99%. The methodis high in welding efficiency, good in welding quality, easy and convenient to operate and low in welding cost.

Abstract: Undercut slope is defined as a slope, which is excavated at its toe. An undercut slope would be failed if undercut width is equal to or greater than its maximum undercut width. Sometimes, the undercut slope is temporarily stable. The undercut slope could displace slowly over a period and it finally fails. The period of undercut slope in stable is called standup time. In this paper, the standup time was estimated by using numerical simulations. A series of numerical simulations using 3DEC was performed to study of standup time of undercut slopes. The numerical models were applied the physical properties and creep parameters of moist sand, which were tested in laboratory. Mohr-Coulomb and Burgers model were assigned to the numerical simulations. The slope inclination of the numerical models was varied. The slope inclinations were 50ᵒ, 30ᵒ, 18ᵒand 15ᵒ. The undercut slope models showed a relationship between slope inclination, undercut width and standup time. When the slope inclination was shallower than the friction angle of bedding plane, its standup time and undercut width were longer and wider than the steeper. The slope inclination was inversely proportional to undercut width while the undercut width was proportion to the standup time.

Abstract: A semiconductor package formed utilizing multiple etching steps includes a lead frame, a die, and a molding compound. The lead frame includes leads and a die pad. The leads and the die pad are formed from a first conductive material by the multiple etching steps. More specifically, the leads and the die pad of the lead frame are formed by at least three etching steps. The at least three etching steps including a first etching step, a second undercut etching step, and a third backside etching step. The second undercut etching step forming interlocking portions at an end of each lead. The end of the lead is encased in the molding compound. This encasement of the end of the lead with the interlocking portion allows the interlocking portion to mechanically interlock with the molding compound to avoid lead pull out. In addition, by utilizing at least three etching steps the leads can be formed to have a height that is greater than the die pad of the lead frame. This differential in height reduces the span of wires used to form electrical connections within the semiconductor package. These reductions in the span of the wires reduces the chances of wire to wire and wire to die short circuiting because the wire sweep of the wires is reduced when the molding compound is placed.

Abstract: The utility model discloses a digital display weld joint detection ruler The invention belongs to the field of measuring instruments, the utility model provides a digital display weld joint detectionruler which can measure the width, the height, the recession and the undercut depth of a weld joint The caliper comprises a caliper body, the caliper body is provided with a caliper and a size display device, the caliper comprises a depth gauge capable of extending out of the tail end of the caliper body, the caliper further comprises an adjusting plate and a weld joint undercut depth measuringdevice, and the adjusting plate is arranged near the tail end of the caliper body; the weld joint undercut depth measuring device comprises a clamp, an adjusting screw and a detection head, and a clamping groove capable of allowing the tail end of the depth gauge to be inserted is formed in the clamp The device integrates the functions of measuring various parameters such as the width, the height, the recession and the undercut depth of the weld joint, is convenient to use and accurate in measurement, avoids errors caused by manual reading, can reduce the number of detection tools, and improves the detection efficiency and the accuracy of measurement results

Abstract: Introduction. The weld formation under the submerged-arc welding of bridge metal structures is investigated. The work objective is to study possibilities to increase the welding performance during the arc welding of fillet seams. Materials and Methods. Methods of computer analysis are used to optimize the technology. With their help, a physicomathematical model of fillet weld formation under the submerged-arc welding has been developed. It is based on a system of equations for thermal conductivity and equilibrium of the weld pool surface. In this system, the formation of an arc cavern is determined through the flux boiling isotherm under the action of the arc column radiation; heat transfer by the flux vapor inside the arc cavern and the influence of the spatial position on the formation of the weld pool are taken into account. Results. New mathematical relationships that describe physical phenomena under the submerged-arc welding of fillet welds are proposed. The key feature of the proposed model is in the fundamental difference between the submerged-arc welding and the gas-shielded arc welding, i.e., during submerged-arc welding, the arc burns in a gas-vapor cavern that appears due to the melting and evaporation of flux. Numerical simulation of the temperature distribution during production of the fillet welds in 1F and 2F positions is carried out. The process constraints under the single-run welding of the fillet welds are specified. It was determined that the single-run submerged-arc welding of fillet welds in 1F position exhibits high-quality formation of welds for almost the entire range of metal sheet thicknesses. During production of fillet welds in 2F position, high-quality formation is provided only for sheet thicknesses up to 8 mm. At heavy thicknesses, the formation of the seam is disrupted due to the melt flow from the vertical wall. In this case, the leg length decreases; a typical undercut is formed; so the weld will be asymmetric and less strong. Discussion and Conclusions. Comparison of the numerical analysis results with actual data on welding modes under the production of bridge metal structures shows that the existing fillet welding technologies have already reached their maximum efficiency rate. Further productivity gain is possible by forming oversized legs only with multiarc or multielectrode welding methods.

Abstract: The invention discloses a vacuum welding device and method of amorphous alloy and relates to the technical field of welding. The vacuum welding device of the amorphous alloy comprises a vacuum mechanism and a welding mechanism. The vacuum mechanism comprises a vacuum cavity and a vacuum assembly arranged in the vacuum cavity and used for conducting vacuumizing treatment on the vacuum cavity. An optical lens is embedded on the vacuum cavity. The welding mechanism comprises a laser device and a welding assembly. The laser device is arranged outside the vacuum cavity. An emission opening of the laser device is opposite to the optical lens. The welding assembly is arranged in the vacuum cavity. The welding assembly is provided with a welding platform used for holding to-be-welded pieces. The welding platform is opposite to the optical lens. By means of arrangement of the vacuum mechanism and the welding mechanism, the vacuum welding device can adopt the vacuum laser welding technology to weld the amorphous alloy in the vacuum environment, so that the joint oxidation problem can be effectively solved; the weld penetration depth can be increased beneficially, the width of a weld seam isreduced, the probability of air pores, undercut and other defects are reduced, and therefore a good weld surface is obtained.