S.Y. Luo

Wear characteristics in turning high hardness alloy steel by ceramic and CBN tools

Abstract The wear behaviour in the turning of AISI 4340 hardened alloy steels by CBN and ceramic tools was studied. Experimental results showed that the main wear mechanism for the CBN tools was the abrasion of the binder material by the hard carbide particles of the workpiece. For the ceramic tools, there was adhesive wear and abrasive wear. It was also found that there was a protective layer formed on the chip–tool interface. For the CBN tool, this was a solution of the binder of the tool material and the work material, while for the ceramic tool, this was from the work material. This layer plays a very important role in the wear behavior of CBN and ceramic tools. Variations of tool wear with the cutting speed and the hardness of the work material are discussed accordingly.

Effect of the geometry and the surface treatment of punching tools on the tool life and wear conditions in the piercing of thick steel plate

Abstract The process behavior in the punching of holes in a larger thickness circular steel plate using punches of different outer diameters, convex double-shear angles, convex lengths, and surface treatments was investigated. Experimental results showed that the appearance of the punched hole for a small clearance between the punch and the die displays a great number of slips to extend almost to the end of the hole through shear. When punches of convex double-shear angles of 20° with surface treatment are used, the straightness and surface finish of the punched hole show a better state. The worn conditions of the punch during shearing can be broadly classified into side wear, face wear, chipping, crack, and gross fracture. The failure mode of a punch with a convex double-shear angle of 12.5° during the piercing holes was mainly side wear. In addition, the worn mode for a punch of a convex double-shear angle of 20° shows dominantly side wear and gross fracture. The tool life for a punch having a convex double-shear angle of 20° is greater than that for a punch of 12.5° convex double-shear angle. The effect of the convex length of the punch on the tool life for a convex double-shear angle of 20° is significant. In addition, the tool life for a punch with a TiC coating or lapping treatment is greater than that of a punch without surface treatment by 25–60%.

Analysis of the wear of a resin-bonded diamond wheel in the grinding of tungsten carbide

Abstract This paper describes experimental results using a resin-bonded diamond wheel in the vertical dry grinding of P10 grade tungsten carbide. The conditions of the diamond abrasive cutting edge on the worn wheel surface, the bonding state between the abrasives and the matrix, and the grinding performance were investigated. It was found that for interrupted dry grinding, the abrasive cutting edges occurring on the worn wheel surface are mainly of protrusive (good) particles and the number of pull-out holes is also high as well, leading the wheel to produce a higher grinding ratio. However, under a greater stock removal rate, the grinding ratio would be reduced rapidly. When continuous dry grinding was employed, the resulting worn abrasives produce a greater proportion of particle pull-out and coated grit exposed on the wheel surface, thereby causing very poor grinding performance. Graphite fillers added to the resin bond have a positive influence on the grinding performance of the wheel in dry grinding. In addition, the roughness of the ground surface is similar to that effected by mechanical polishing.

A thermal model of the wet grinding process

Abstract A thermal model of the wet grinding process is presented. The thermal effect of the grain–workpiece interface and the shear plane between the workpiece and the chip is taken into account. By taking all of the parameters needed in the model from the experimental results, the temperature of the workpiece surface in the grinding zone can be predicted. It is shown that the flow rate of the grinding fluid under general grinding conditions is sufficient to cover the thermal boundary layer of the coolant in the grinding zone. The predicted workpiece surface temperatures have been compared to experimental data for some grinding conditions. Good agreement is obtained except for the creep-feed grinding process, when water-based grinding fluid is used. The differences between the theoretical values and experimental results are attributed to constant thermal properties, and neglect of transverse conduction in the development of the thermal model.

Performance of powder filled resin-bonded diamond wheels in the vertical dry grinding of tungsten carbide

Abstract Grinding performances of several resin-bonded diamond wheels containing copper, silicon carbide and carbon black fillers in the vertical dry grinding of cemented tungsten carbide are studied. The experimental results showed that the resin-bonded diamond wheel with the greatest amount of copper filler resulted in a relatively higher proportion of protrusive particles and partial breakage grits and a smaller number of pull-out holes occurred on the bond surface, which leads the wheel to produce relatively higher grinding forces and temperatures. The resulting grinding ratio is relatively low. The grinding forces and temperatures produced for the wheel containing silicon carbide and copper filler increase with the increase of the proportion of silicon carbide filler. Small amounts of carbon black filler added into the wheel containing copper filler can obtain the positive effect with the decrease of the grinding forces and the wheel wear. However, the grinding temperature produced during the dry grinding is still relatively high. Low grinding ratio produced in the vertical dry grinding is mainly attributed to high temperature and the grinding mechanism.

Applying patent information to tracking a specific technology

Patents in general contain much novel technological information. This paper demonstrates that the usage of patent analysis can facilitate a unique scheme for tracking technology development. In this paper, the walking technique of the Japanese biped robot is tracked as an example. The searching method of the FI (file index) and F-term classification system developed by JPO (Japan Patent Office) was employed in this study, where all the related patent data were searched from the IPDL (Intellectual Property Digital Library). This study investigated an important technique applied to the humanoid biped robot that imitates the walking behavior of the human beings on two legs. By analyzing the patent information obtained, the relative research capabilities, technical strengths, and patent citation conditions among patent competitors were compared. Furthermore, a formulated technical matrix of patent map is established in this paper to indicate that the ZMP (Zero Moment Point) control means is the main technology to achieve stabilized walking control of the humanoid biped robot. This study also incorporates relevant academic journal findings and industrial information. Results presented herein demonstrate that patents can function not only as a map for tracking a technology trajectory, but also as a guide to the main development of a new technology in years to come.

Analysis of the Vitrified CBN Wheels for the Performance of Grinding Hardened Steel

This paper investigates the effect of the CBN abrasive types, sizes, concentration, bond amount, and porosity of a vitrified-bonded CBN wheel on grinding ratio, grinding forces, and surface roughness of grinding hardened steels. The experiment results showed that during grinding hardened steels the amount of bond with increase of the depth of cut increased, which makes the wheel to have a better bonding strength to get a better grinding ratio and surface roughness of the workpiece. The grinding forces produced increased with the increase of the depth of cut. In addition, too much porosity of a vitrified CBN wheel will cause the low bond strength, leading the wheel to wear rapidly. Hence, to obtain a higher grinding ratio and better surface roughness of the workpiece during the grinding hardened steels should select relatively a higher amount of bond, a lower porosity, and a higher grit strength and concentration, but the grinding forces produced were relative higher.

Analysis of developing a specific technological field using the theme code of Japanese patent information

The paper was to establish an easy and effective method to investigate and develop a specific technological field from Japanese patent information. The walking technique of the biped humanoid robot was used as an example to study the relative research capabilities and patent citation conditions for patent owners and patent map by the searching method of the theme code for FI (File Index) and F-term classification system of the Japanese Patent Office (JPO). A formulated technical matrix of patent map was established to indicate that the ZMP (Zero Moment Point) control means was the main technology to achieve stabilized walking control of the humanoid biped robot. This method can aid to establish a specific technological matrix from the specific selected term codes (single viewpoint or multiple viewpoints) of the F-term list in the theme code of the JPO system through Boolean logical operations. The resulting particular technical fields were developed to improve the technological capability or seek the merging technology opportunities.

Investigation of Surface Roughness for Grinding Silicon Wafer of the Micro Pellet Diamond Tool

The purpose of this paper was to investigate the silicon wafer surface roughness ground by the micro pellet grinding tool and the electroplated disc grinding tool with diamond grit size of 4-6 μm and 10-20μm under the spindle rotation speed of 500-2500 rpm and the feed rate of 1-5 μm/min. The results showed that the micro pellet grinding tool can get a better surface roughness of the silicon wafer than the electroplated disc tool. When the tools containing a larger diamond grit were employed, selecting a higher spindle rotation speed and a lower feed rate can obtain a better wafer roughness. However, when the tools of a smaller diamond grit were used, the spindle rotaion speed operates properly at a optimal value to obtain a best wafer surface roughness, which achieves Ra = 0.03-0.06 μm for the micro pellet tool. Besides, the material removal mechanism during the grinding silicon wafer for these two tools displayed mainly ductile grinding behavior.

Study of Metal Friction Materials Using Hot Press

The metal friction materials of copper matrix with and without resin using hot press were investigated to study their hardness, porosities, bending strengths, microstructures, coefficient of frictions, and wear mechanisms. The experiment results show that the hardness and bending strength of the friction materials with increase of amount of copper increase, but the porosity decreases. The resulting coefficient of frictions show more stable and their values are about 0.5~0.6. In addition, the wear mechanism of friction material shows mainly grit abrasive and adhesion, which cause the coefficient of friction to become stable. On the other hand, when the copper matrix containing resin is used, the resulting porosity of friction materials becomes higher and the bending strength decreases. This shows that the wear mechanisms of grit abrasive, roughness, and adhesion cause the coefficient of friction to produce a higher value.