Flange Portion Research Articles

ホットスタンピングにおけるフランジ部温度低下抑制による鋼板の成形性向上

The formability of quenchable steel sheets in hot stamping was improved by preventing the decrease in the temperature of the flange portion of a formed cup. The effects of forming speed on the distributions of the temperature and wall thickness of the formed cup were examined in an experiment on hot drawing with a hemispherical cylinder punch. The decrease in the temperature of the flange portion caused by contact with a die and a blankholder was prevented by high-speed forming using a mechanical servo press. Thus formability was improved by decreasing the drawing resistance of the flange portion. To improve formability in low-speed forming using a hydraulic press, a spacer thicker than the blank was inserted between the die and the blankholder. The decrease in the temperature of the flange portion was prevented by decreasing the extent of contact with the die and blankholder owing to the gap generated by the spacer. In addition, the quenching of the flange portion was prevented by generating a gap to facilitate the trimming of the flange portion.

Nonlinear analysis of cellular steel beams under combined buckling modes

This paper discusses the nonlinear analysis of normal and high strength cellular steel beams under combined buckling modes. A nonlinear 3-D finite element model has been developed, which accounted for the initial geometric imperfection, residual stresses and material nonlinearities of flange and web portions of cellular steel beams. The nonlinear finite element model was verified against tests on cellular steel beams having different lengths, different cross-sections, different loading conditions and different failure modes. Failure loads, load–mid-span deflection relationships and failure modes of cellular steel beams were predicted from the finite element analysis. An extensive parametric study involving one hundred and twenty cellular steel beams was performed using the verified finite element model to study the effects of the change in cross-section geometries, beam length and steel strength on the strength and buckling behaviour of cellular steel beams. The results of the parametric study has shown that cellular steel beams failing due to combined web distortional and web-post buckling modes exhibited a considerable decrease in the failure loads. It is also shown that the use of high strength steel offers a considerable increase in the failure loads of less slender cellular steel beams. The failure loads predicted from the finite element model were compared with that predicted from Australian Standards for steel beams under lateral torsional buckling. It is shown that the Specification predictions are generally conservative for normal strength cellular steel beams failing by lateral torsional buckling, unconservative for cellular steel beams failing by combined web distortional and web-post buckling and quite conservative for high strength cellular steel beams failing by lateral torsional buckling.

Trial Computation of Dynamic Axial Compression of Adhesive-Bonded Tubular Structure

The dynamic axial compression of adhesive-bonded tubular structures with hat-shaped cross-section was numerically investigated using dynamic explicit finite element method. The numerically modeled Type I tubular structure consisted of a hat-shaped part and a flat plate. Type II consisted of two hat-shaped parts. The hat flange portion was assumed to be joined by adhesive bonding. The impact velocity of 10 m/s was given. Parametric computation was performed, where thicknesses of the plate and adhesive layer, and mechanical properties of the plate material were varied. As the result of computation, separation behavior of the hat flange portion was almost avoided for the case where the strength of plate material was lower. However, it was clearly observed for the higher strength material, though the plate was thin. The separation of the flange portion in Type I structure was more remarkable in comparison with that in Type II. The crush strength increased as the thickness of the adhesive layer thickened, when the plate thickness was thin and the strength was low. The Type II structure exhibited larger crush strength than that of Type I.

Study on Bending Strength of Web-Bolted Moment Joints of Aluminum Alloy Beam Exposed to Fire

This study narrows the application temperature field of aluminum alloy to 350°C or less, and examines the transformation of strength properties in web-bolted moment joints. The following results are obtained by it is clarified experimentally and analytically that the bending strength of web bolted moment joints of aluminum alloy beam exposed to fire. 1)The maximum bearing moment of the beam with the web-bolted moment joint is almost equal to the moment of a beam without a joint. 2)The effct of prying action contributes to the maximum bending strength. It accounts for an increase of 90% from 60%, and the contribution of the bolt is 40% to 10%. 3)In specimens tested in the range of room temperature to 250°C, there was tensile fracture by the bearings, prying action between the boundary of the web and the flange portion, and punching shear fracture. 4)For the specimens tested at 300°C and 350°C, because the bending transformation by the prying action had progressed, brittle fracture was not seen.

Study on Bending Strength of Web-Bolted Moment Joints of Aluminum Alloy Beam Exposed to Fire

This study narrows the application temperature field of aluminum alloy to 350°C or less, and examines the transformation of strength properties in web-bolted moment joints. The following results are obtained by it is clarified experimentally and analytically that the bending strength of web bolted moment joints of aluminum alloy beam exposed to fire. 1)The maximum bearing moment of the beam with the web-bolted moment joint is almost equal to the moment of a beam without a joint. 2)The effct of prying action contributes to the maximum bending strength. It accounts for an increase of 90% from 60%, and the contribution of the bolt is 40% to 10%. 3)In specimens tested in the range of room temperature to 250°C, there was tensile fracture by the bearings, prying action between the boundary of the web and the flange portion, and punching shear fracture. 4)For the specimens tested at 300°C and 350°C, because the bending transformation by the prying action had progressed, brittle fracture was not seen.

Friction aided deep drawing of aluminum sheet using blank holder divided into four segments

A novel process of friction aided deep drawing has been developed by employing divided blank holder. In this process, a conventional circular blank holder is divided into eight segments, each of which can move radially inwards and outwards. When these segments are compressed in the axial direction, the frictional force is generated at the contact surface between a sheet blank and the blank holding segments. These frictional forces contribute to the drawing deformation of a sheet blank on the flange portion. Deep drawn cups can be produced successfully by repeating such operations of loading and unloading. The cup surface also becomes satisfaction compared with the case of four segments. Deep drawing experiments were carried out to improve the surface condition, the shape and dimensions of cups. A supplemental punch is also used to carry a small amount of drawing force and to keep the size and shape of the drawn cup. The experimental resu1ts show that the deep drawing of soft aluminum sheets of 0.5 mm in thickness was produced by repeating this drawing process. A potential of the proposed process was confirmed by successfully producing deep cups 74 mm in height with a drawing ratio of 4.0.

薄鋼板の伸びフランジ変形限界に及ぼすひずみ勾配の影響

The effect of strain gradient on the stretch flange deformation limit of steel sheets was investigated by hole expansion test under some forming conditions and by FEM. Hole expansion ratio was changed by changing initial hole diameter and punch shapes. It was clarified that limit deformation strain increases as it does not depend on initial hole diameter or punch shape, and thus strain gradient increases. The strain gradient along the direction toward the maximum principal strain did not affect limit deformation strain. The limit deformation thickness strain of the stretch flange portion could be changed by changing strain gradient. The sensitivity of the effect of strain gradient on limit deformation strain tended to increase as material yield ratio increased. These results suggest that the formability of stretch flange deformation area should be determined from not only the maximum principle strain but also the strain gradient and blanking clearance.

Acoustic septum cap honeycomb

An acoustic structure that includes a honeycomb having cells in which septum caps are located. The septum caps are formed from sheets of acoustic material and include a resonator portion and a flange portion. The flange portion has an anchoring surface that provides frictional engagement of the septum caps to the honeycomb cells when the caps are inserted into the honeycomb during fabrication of the acoustic structure. An adhesive is applied to the anchoring surface of the septum caps after the caps have been inserted into the honeycomb cells to provide a permanent bond.

Sound absorbing panel

A sound absorbing panel comprising a generally rectangular mat of sound absorbing material, a plastic non woven covering at the frontal mat surface facing towards the sound insulated space and a sheet metal plate covering at the rear. The sheet metal plate covering extends outwardly perimetrically around the mat and forms uniformly sized flange extensions bent inwardly by 180° to form lip portions and corresponding recessions between the flange extensions and associated lip portions. Four Z section edge members are employed, one for each of the four lateral sides of the mat, each Z section edge member comprising a base portion abutting the lateral side of the mat and two spaced apart flange portions projecting in opposite directions from the base portion, one of these flange portions entering within the abovementioned recessions of the sheet metal plate covering wherein it is being pressed to form a compact frame structure perimetrically around the sound absorbing panel.

Deep drawing with developed blank of aluminum sheet without blank holder

Using the developed blank, it is possible to form the deep container in one stage. The conventional deep drawing is carried out using punch, die and blank holder. Deformation of divided flange portion of the developed blank seems to be small in the deep drawing. It is possible to carry out the processing without blank holder. When the blank holder is not used, the processing condition in which the forming become very severe. If the case in which the blank shape is not appropriate, gap occurs between flanges or overlap generate on the flange. In this paper, the examination was carried out in detail on flange state of the developed blank. The result was showed that the shape of the flange is no necessity of satisfying the condition of “the circular arc length is constant”, and the forming is possible in the flange of shape of “parallel linear”. Blank shape that was optimum for carrying out the drawing without blank holder was clarified.

アルミニウム合金梁ウェブ曲げ継手の火災時曲げ耐力に関するてこ作用の影響

This study indicates the influence of the prying action on Web bolted moment joints of aluminum alloy beams and splice plates. In this joints, the gap can be rather narrow between the beam flange and the splice plate side edge because of aluminum extrusion. Web bolted moment joint can transmit the bending moment by bearing of the bolts and the prying action between the beam flange and the splice plate side edge. The bending moment of prying action is neglected usually. In this paper, it is clarified experimentally and analytically that the bending strength ratio of prying action reaches to 60%-90% for the maximum bending strength. After each experiment, the phenomenon of tensile or punching shear fracture has been observed at web or flange portion of beam in a specimen.

Forming square cup with developed blank of aluminum sheet

Using conventional deep drawing method, it is difficult to make square cups taller than the length of straight side of punch in only one stage drawing. This is because, in case of using a conventional, the drawing resistance of blank material is too high to draw material into die hole by punch. From simple consideration, by using the developed blank, the flange portion of which is divided into four elements, the drawing resistance of blank material can be reduced considerably, and so this problem can be overcome. In this investigation, a deep drawing process of square cup was attempted using a developed blank instead of an octagonal or ellipse blank. By introducing assumption of the constant arc length, the shape of developed blank was designed. It was clarified that, when developed blanks with appropriate shape was employed, very tall square cups could be obtained in one stage drawing.

Production of deep container with developed blank of aluminum sheet

Using conventional deep drawing method, it is difficult to make cups or containers taller than the diameter of the cup in only one stage drawing. This is because, in case of using a blank with large diameter, the drawing resistance of the blank material is too high to draw material into die hole by punch. From simple consideration, by using the developed blank, the flange portion of which is divided into four elements just like a petal, the drawing resistance of blank material can be reduced considerably, and so this problem can be overcome. In this investigation, a deep drawing process was attempted using a developed blank instead of a conventional circular or square blank. At first, by introducing two assumptions of the parallel moving and the constant arc length, the shape of developed blank was designed. After that, the effects of the shape of developed blank on the drawn cup were investigated. Finally, it was clarified that, when developed blanks with appropriate shape was employed, very tall cups could be obtained in one stage drawing.

Forming of tailor blanks having local thickening for control of wall thickness of stamped products

A two-stage forming process of tailor blanks having local thickening for controlling the distribution of wall thickness of stamped parts was developed. In the 1st stage, the target portion of the sheet for the local thickening is drawn into the die cavity, and then the bulging ring is compressed with the flat die under the clamping of the flange portion in the 2nd stage. The effects of the punch stroke, the clearance between the punch projection and die, and the projection width on the amount of the location thickening were examined. A 12% increase in thickness of the blank was obtained in an experiment. The tailor-formed blank having local thickening was applied to increase the wall thickness at the inner corner of a wheel disk. An 11% increase in wall thickness at the inner corner was successfully obtained in the experiment. The tailor blanks having local thickening obtained by the two-stage forming process are effective in controlling the distribution of wall thickness of the stamped parts.

Hearing-aid anchoring element

A hearing aid anchoring fixture (104) for anchoring a direct bone conduction hearing aid (108) to the skull bone (106), comprising a threaded portion (110) that has at least one cutting edge (118). Each cutting edge (118) has an adjacent cavity (120) having a volume Vc. The threaded portion (110) has a thread depth dt being half of the difference between the maximum outer diameter d1 of the threaded portion (120) and the inner diameter d2 of the thread, where dt is at least 10% of the maximum outer diameter d1 of the threaded portion (110) and where dt is less than 20% of the maximum outer diameter d1 of the threaded portion (110). The fixture (104) may be equipped with a flange portion (114) that has an outer diameter d3 being greater than the maximum diameter d1 of the threaded portion (110).

張出・逆張出・しごき複合加工による張出高さの向上

In the bulging, the material existing at the flange portion is not drawn into the die opening, and so the contour of a metal sheet does not change. This feature of the bulging is advantageous to producing cups with wide flange. On the other hand, there is a weak point that it is difficult to make cups with large height by the bulging. In this study, in order to improve the bulge height, the method for flowing the material of the flange region to the die hole was examined. A new processing combined bulging, reverse re-bulging and ironing was tried. Variations of thickness strain distribution by each process were measured and the effectiveness of the process was clarified. Finally, it was possible to make a bulged cup about 3.1 times as high as that made by conventional stretching.

張出・しごき複合加工によるフランジ付き深い容器の作製

In the bulging, the material existing at the flange portion is not drawn into the die opening, and so the periphery of a metal sheet blank does not change. This feature of the bulging is advantageous to producing cups with wide flange. On the other hand, there is a weak point that it is difficult to make cups with large height by the bulging. This is because the thickness of metal sheet at punch shoulder decreases locally and it results in a quick breakage at this portion. At this point, the thickness of the sheet at the other portions, e.g. punch head and sidewall, has been little decreased. Therefore, if the thickness of the sheet metal could be decreased more uniformly in the bulging, producing shells with wide flange and large height becomes possible. In this study, in order to get higher cups with wide flange, a new process of bulging combined with ironing was tried. In the new process, a hemispherical rubber punch and metal counter punch were used for thinning material at punch head. And the material at sidewall of the stretched cup was thinned by a following ironing process. Variations of thickness strain distribution by each process were measured and the effectiveness of the process was clarified. Finally, it was possible to make a stretched cup twice as high as that made by conventional bulging.

金属板材のスプリングバックレスV曲げ加工

When a bent part is unloaded at a certain stage in a V-bending process, a springback phenomenon does not occur. The purpose of this study was to develop a practical V-bending process to exploit a springback-less phenomenon. The mechanism of this springback-less phenomenon is as follows. Under a certain punch stroke in the V-bending process, the “springback” factor due to tensile stress on the outer side of the bend is precisely balanced by the “spring-go” factor due to tensile stress on the inner side of the bend, which occurs by the unbending of the flange portion of the bent part at the punch shoulder. To realize this bending method, it was shown that it is possible to predict where in the punch stroke the springback-less state will occur, regardless of the thickness and property changes of the sheet metal, and dimensional changes of the bending die. It was also shown that the bending die specifications for a right-angle bending can be predicted on the basis of the thickness and property of the sheet metal. Examination was performed with press brakes attached to a device for measuring the bending load, bending angle and punch stroke. In addition, the FEM simulation of the bending process was carried out.

Inverse finite element approach and its application in sheet metal forming

The inverse finite element approach (IFEA) was derived from ideal forming to predict the development blank of sheet metal and the thickness strain distribution according to the geometry of final product. The flange portion of stamping product under blank-holder is a free parameter that is mostly dependent on the shape of the initial flat blank. Based on the IFEA, this paper proposed a node relocation technique to estimate the influence of flange shape and evaluate the final geometry and thickness strain distribution from the prescribed flat blank. The applications of the IFEA cover the backward and forward evaluations: from given product to initial blank and from given initial blank to final product. Those applications make the design of sheet metal forming easy and fast. A door-like product experiment confirmed that the precision of the IFEA satisfied the manufacturing requirement.

Implantation of a keratoprosthesis of novel design in rabbits.

To evaluate a keratoprosthesis, implanted by penetrating keratoplasty, in rabbits. We implanted our keratoprosthesis (optics and flange portions of polymethylmethacrylate and a polyurethane skirt with micropores) into 14 eyes of 14 rabbits. In four eyes, we evaluated histologically the junction between the keratoprosthesis and host cornea. Long-term keratoprosthesis survival was evaluated in ten eyes by slit-lamp biomicroscopy. The histological study showed good approximation of the keratoprosthesis to the host cornea in the junction area, with overlying superficial corneal stroma on the skirt, keratocyte and collagen fiber ingrowth into the micropores, and partial migration of epithelial cells onto the skirt. However, in the long-term survival study, eight out of ten eyes developed acute suture-related inflammation, considered to be from bacterial infection, requiring enucleation 30 +/- 18 weeks after implantation. The remaining two eyes have survived for 70 and 76 weeks. Our keratoprosthesis was well tolerated in the short term. However, further modifications are necessary to avoid corneal infection.