Masayoshi Tateno

Effects of the Supplied Cold-Air Condition on Grinding Temperature in Cold-Air Jet Grinding

Eco-development on grinding has recently become the center of interest in mechanical manufacturing fields. In order to improve the environment of grinding, establishing a technology of eco-friendly grinding without using cutting fluid, one of which is the cold-air jet grinding, has been required because of the need to reduce air pollution and the problems in the disposal of used cutting fluid. The performance index of the cold-air jet grinding, the dressing interval, has a remarkable improvement over the one with cutting fluids currently in use. Although the cold-air jet grinding is advantageous to improve the environment, the mechanism of improvement in dressing interval in cold-air jet grinding has not been clarified experimentally. The grinding temperature, the temperature at the grinding point, and the internal temperature in the workpieces for each cold-air jet condition should be investigated to understand the mechanism. In this study, the grinding temperatures were experimentally measured by using a grinding temperature measuring system. A relationship between the grinding temperature and the cold-air jet supply pressure is found experimentally and numerically.

Dependence of Bonding Temperature Conditions on Metal Thickness Effects in Bonded Dissimilar Materials

This study provides information on the dependence of bonding temperature conditions on metal thickness effects in bonded dissimilar materials as a composite material system. Effects of metal thickness on the bonding strength were confirmed each bonding temperature condition by using silicon-nitride and nickel to confirm for each joint manufactured by a bonding method, two stages bonding process. This process used in this experiment consists of two stages, first bonding process as the ceramic is bonded to thin layer metal at high temperature, and secondary process as thick metal is bonded to the thin metal layer of the joint at lower temperature than first stage’s one. Bonding tensile strength of the joint specimen was evaluated experimentally. The bonding strength was dominated by the residual stress near the edge of the interface on ceramic side. The maximum bonding strength appears at optimum metal thickness. It shows that the optimum metal thickness depends on the first temperature condition. Reduction of the residual stress was considered based on the experimental and numerical results. Two stages bonding process can be applied for high strength bonded dissimilar materials as useful engineering application by setting optimum metal thickness each bonding temperature condition.Copyright

Effects of Metal Thickness on Bonding Strength in Bonded Dissimilar Materials

This study provides effects of metal thickness on bonding tensile strength of ceramic to metal joint based on numerical and experimental analyses. Thermal elastoplastic FEA was carried out to clarify effects of the metal side thickness on the stress distribution near the edge of the interface on ceramic side by changing metal side thickness each bonded silicon nitride to nickel joint system. It was confirmed the stress distribution on the ceramic of the joint system depends on the metal side thickness based on the FEM results. Decreasing of metal thickness reduces the intensity of the stress near the edge of the interface on ceramics side. It can be effective for reduction of the residual stress near the edge of the interface to use thin metal layer in the ceramic to metal joint.Reduction effects on the residual stress were confirmed by using two stages of bonding processing. This process used in this experiment consists of two stages, first bonding process as the ceramic are bonded to thin layer metal at high temperature, and secondary process as thick metal are bonded to the thin metal layer of the joint specimen at lower temperature than first stage. The bonding tensile strength of the joint specimens manufactured from the two stages bonding processe was evaluated experimentally. It appears that setting a ratio of metal thickness to length of the interface to approximate tm/W=0.08 achieves maximum bonding tensile strength. Effects of metal thickness on bonding tensile strength of ceramic to metal joint are confirmed based on numerical and experimental results.© 2014 ASME

Dependence of Tensile Strength on Geometrical Interface Conditions of Bonded Dissimilar Materials

Many engineering structures applied for generating energy are said to have been requiring high strength under high temperature conditions. Fine ceramic is expected to be useful in structural applications in various industries by joining to metals. Ceramic can be used in structural parts for engineering where resistance to high temperature and/or high strength are required from the viewpoint of the optimum structural design. Use of ceramic for engineering structures by joining to metal generates a bonded interface between the ceramic and metal.Copyright

Dependence of Bonding Strength of Ceramic to Metal Joint on Interface Wedge Angle in Metal Side

The focus of this study is to clarify a dependence of bonding strength of ceramic to metal joint on interface wedge angle in metal side. Each plate Si3N4-to-Cu or Ni joint with plane interface is produced by electric discharge machining. Geometrical shape at the edge of the interface is characterized by wedge angle defined as a configuration angle between free surface of each material and the interface. As the wedge angle of Si3N4 is right angle, the wedge angle of metal is set over from 30° to 180°. Each joint is bonded at high temperature by using thin braze metal under vacuum and slowly cooled. Tensile bonding strength of the joint is evaluated. Result shows that decrease of the wedge angle of metal side from right angle improves the bonding strength since it decreases the residual stress near edge of the interface on ceramic side. The highest bonding strength appears at the identical interface condition where fracture pattern changes. It appears that optimum edge angle for obtaining the highest bonding strength depends on bonding temperature and combination of bonded materials. This paper provides a useful geometrical interface shape to improve tensile bonding strength of ceramic to metal joint.Copyright

Relationship Between Singularity Strength Factors and Practical Bonding Strength of Ceramic to Metal Joint

This study correlates the stress intensity factors (Kii , Kpaii ), the order of the stress singularity p-1, and the practical bonding strength of ceramic to metal joints with arbitrary interface geometry. First, in order to describe the stress behavior of TiB2 to Ni joints bonded at 1173K, the stress singularity factors (Kii , Kpaii , p-1) were theoretically derived for wedge angles of φ1 :30°<φ1 <150°. Secondly, the dependences of the singularity factors on the wedge angle φ1 were compared with experimental results using the same wedge angles on TiB2 to Ni joints with interface convexity or concavity produced by Electric Discharge Machining (EDM). In order to obtain the highest strength joints, the optimum interface shape is determined using the relationship between the singularity factors.Copyright

Effect of Interface Wedge Angle in Ceramic Side on Tensile Bonding Strength in Ceramic to Metal Joint

This study was performed to clarify the dependence of ceramic-to-metal joint bonding strength on the interface wedge angle on the ceramic side. Plate Si3 N4 -to-Ni joints with a plane interface were produced by electric discharge machining. The geometric interface shape at the edge of the interface is characterized by wedge angle on both sides of the ceramic and metal defined as a configuration angle between the free surface of each material and the interface. As the wedge angle of Ni is a right angle, the wedge angle of Si3 N4 is set from 30° to 180°. Joints were bonded at high temperature using thin braze metal under vacuum and cooled slowly. The tensile bonding strength of the ceramic-to-metal joint was evaluated to determine the optimum interface shape. The highest bonding strength appeared under identical interface conditions where the fracture pattern changed. The optimum wedge angle to obtain the greatest bonding strength appears to depend on bonding temperature. This study provided a useful geometric interface shape to improve the tensile bonding strength of ceramic-to-metal joints.Copyright

Effect of Free Surface Shape at Edge of Interface on Bonding Strength of Ceramic to Metal Joint

The focus of this study is to clarify the effect of the interface edge shape on the bonding strength of ceramic to metal joint. Each silicon nitride to copper joint plate with arc-shaped free surfaces edge was produced by Electric Discharge machining (EDM). The interface edge shape was characterized by defining the edge angle as a configuration angle between the interface plane and tangential line at the arc edge of the bonded interface. Each joint was bonded at high temperature using thin braze metal under vacuum and slowly cooled. Good fit was achieved at each bonded face in this process. The dependence of the bonding strength on the edge angle was experimentally clarified in Silicon nitride to Copper joint with arc-shaped free surfaces. The result shows that changing the edge angle from right angle improves bonding strength since it decreases residual stress near the interface edge. The highest bonding strength appears at the specific interface where the fracture pattern changes. It also shows that secondary machining, which cuts both edges into optimum geometrical conditions after bonding, can improve bonding strength.Copyright

Effect of Interface Edge Shape on Bonding Strength in Ceramic to Metal Joint

Selection of the optimum shape for interface edge can produce significant increases in the strength of bonded dissimilar materials such as ceramic to metal joints. The focus of this study is to clarify an effect of interface edge shape on bonding strength of ceramic to metal joint. Each plate Si3 N4 to Ni joint with arc interface of convexity or concavity is produced by Electric Discharge machining. The arc interface is characterized by edge angle defined as a configuration angle between tangential line at the edge of the interface and the free surface of the ceramic. Each joint is bonded at high temperature by using thin braze metal under vacuum and slowly cooled. A good fit on each bonded face is achieved in this process. The dependence of the bonding strength on the edge angle is experimentally clarified. The result shows that changing the edge angle from the right angle improves the bonding strength since it decreases the residual stress near edge of the interface. The highest bonding strength always appears at the identical interface condition where fracture pattern changes. It appears that the optimum edge angle for obtaining the highest bonding strength depends on bonding temperature.Copyright

Development of Supersonic Convergent-Divergent Nozzle for Cooling Air Jet Turning And Its Cooling Ability

Cooling air jet turning needs to develop a supersonic nozzle that is capable of supplying high speed air jet at turning point. In this study, supersonic Convergent-Divergent nozzle (supersonic C-D nozzle), which can make stagnation-cold-air up to the sound speed in the convergent section and expand the cold air to supersonic speed in the divergent section, are designed on an assumption of thermal equilibrium under isentropic expansion (no change in entropy). Experimental evaluation of the supersonic air jet clarifies that the C-D nozzle is more advantageous than present convergent nozzle for the cooling air jet turning since the potential core of the C-D nozzle goes over 13 mm (max. 37 mm). As for cooling ability of the cold air jet in the potential core, average heat transfer coefficients of the cold air jet are 1,000-1,400W/(m2K) depending on both pressure of chamber p0 and impinging jet air P. The optimum supply condition of each nozzle is verified experimentally and expressed using non-dimensional parameters, Reynolds number Re and Nusselt number Nu.