Akihiro Yamamoto

Finishing Characteristics in Barrel Finishing of Centrifugal Disc Type on Flow-Through System

For the improvement of the performance in centrifugal disc finishing, the flow-through system for supplying the compound solution is tried and its influences on finishing characteristics are experimentally investigated. Workpieces (22 mm in diameter and 15 mm in thickness) of plain carbon steel (S45C in JIS), aluminum alloy (A2017) and copper alloy (C3604) are finished with ceramic media (Equilateral triangular prism 6 mm in side and 5 mm in thickness). The conclusions are summarized as follows; The compound solution has more influences on finishing characteristics than plain water. It makes the relative stock removal larger and the surface roughness smaller than the water. The relative stock removal and the media weight loss on the flow-through system are larger than those on the batch system.

A Try for Improvement of Performance in Dry Barrel Finishing by Centrifugal Disc Type

The speed-up of the disc rotation in dry centrifugal barrel finishing is done and its influence on finishing characteristics is experimentally examined. The workpiece is a sliced cold rolled bar of plain carbon steel (S45C in JIS, HB221). It is 32mm in diameter and finished to10mm in thickness by belt grinding. The equilateral triangular prism nylon media (1010mm, A#320) is used at 20vol% in media charging ratio. The disc rotation speed is increased up to 500min-1. By speeding up the disc rotation, the finishing speed improves, but the total efficiency decreases.

Conversion of Power Density Distribution with Kaleidoscope in Laser Processing. Application of Cylindrical and Taper Pipe Kaleidoscope to Laser Drilling.

Kaleidoscope is a device to convert power density distribution of laser beam. Cylindrical pipe kaleidoscope and taper pipe kaleidoscope are applied to laser drilling process in the present research. The shapes and dimensions of the kaleidoscopes are designed based on the theoretical analysis of the power density distribution of the laser beam converted by the kaleidoscopes. Laser drilling experiments of acrylic resin plates are carried out by applying both the kaleidoscopes and the conventional lens. The experimental results are discussed from the viewpoints of the depth and the cylindricity of the acrylic burn patterns. The following remarks are concluded based on the experiments. The shapes and dimensions of the burn patterns are not affected so much by the distances between the kaleidoscopes and the work plates in the case of drilling process by use of the kaleidoscopes. The taper pipe kaleidoscope is most suitable for the drilling process from the viewpoint of the cylindricity of the burn patterns.

Conversion of Power Density Distribution with Kaleidoscope in Laser Processing. Evaluation of Power Density Distribution by New Knife Edge Method.

A pinhole method is applied to evaluate power density distribution of laser beam converted by a kaleidoscope for CO2 laser processing. An experimental method is developed to measure the power density distribution of the laser beam with use of a pinhole and a thermocouple. Theoretical analyses are carried out to evaluate the power density of the laser beam through the pinhole at the point of the thermocouple. A form error coefficient is proposed to compensate the loss of power when the laser beam is reflected in the kaleidoscope. The theoretical distribution of the power density is in good agreement with the one obtained by the experiments. It is concluded, through both the theoretical analysis and the experiments, that the pinhole method is effective to evaluate the power density distribution of the laser beam converted by the kaleidoscope.

Conversion of Energy Density Distribution with Kaleidoscope for Laser Processing. Effect of Taper Pipe.

A method is proposed to convert the energy density distribution of the laser beam to an adequate one for laser processing by applying a kaleidoscope of taper pipe taking a case of CO2 laser as an example. The energy density distributions of singlemode and multi-mode laser beams obtained by a kaleidoscope of taper pipe were calculated for cases in which the interferences of the beams were disregarded and also the interferences were taken into consideration. It is confirmed that the energy of the laser beam can be concentrated to its center in narrow ranges with use of the kaleidoscope of taper pipe. The optimum geometries of the kaleidoscope are also obtained through the calculations to concentrate the energy density distribution. In order to confirm the effect of the kaleidoscope, experiments were carried out to measure the energy density distribution of single-mode laser beam with use of the knife edge method, and the acrylic burn patterns were made with the single-mode laser beams concentrated by different methods. The experimental results were in good agreement with the calculations.