Experimental studies on gear-honing-tool with laser brazing film CBN
During the process of brazing cubic boron nitride (CBN) gear-honing-tool by Laser, cleaning of the gear-honing-tool and film plating CBN abrasive, and the thickness of brazing coating directly affect the quality and life of gear-honing-tool. In the paper, based on experiment the process of laser brazing CBN is summed up, the thickness interrelationship of brazing filler metal from beginning to end is obtained, the rule of laser facula's moving speed is studied on solder layer thickness and the radial change of gear tooth thickness. It is shown that the bonding among CBN, gear-honing-tool and solder can be realized by laser brazing. In order to improve quality of brazing, the moving speed of laser facula must be reduced along radial direction of gear honing tool. As to different size of CBN abrasive, the thickness of solder layer should be varied so that the bare rates of cutting edge can be ensured. The solder layer thickness should be controlled between 1.25 and 1.5 times of average size of abrasive grains. The thickness of solder layer depends on laser energy and soldering time that can be controlled by the moving speed of laser facula.
On Performance of Brazed Single-Layer CBN Wheel
Summary In brazed single layer CBN wheel, high grit exposure but with strong grit-bond adhesion is known to be the most distinguished feature. The present investigation has, however, revealed that in spite of having a large grit protrusion, the consistency of performance of such a wheel may be affected by the manner how the density as well as the uniformity of grit distribution are regulated in the monolayer configuration. This is particularly true when a chip accommodation problem leading to wheel loading exists. Experiments with monolayer CBN wheel varying in grit density and under various grinding conditions have further revealed that pre-brazing placement and fixation of CBN grit on the tool substrate with an even distribution and adequate inter-grit spacing may remarkably enhance the flexibility of application of a high protrusion single-layer CBN wheel.
CBN or CD Grinding of Profiles
Summary In practice, profiles in difficult-to-machine materials are ground by means of CD grinding or by using CBN wheels. Both processes permit manufacturing at high cutting speeds and produce a high shape accuracy and a high surface quality. In CBN grinding, this is achieved through the use of vitrified bonded or electroplated CBN wheels. The comparatively low wear of this wheel type allows constant operating conditions even at high speeds. In CD grinding, conventional grinding wheels are kept in almost constant condition through continuous conditioning. However, conditioning reduces the wheel volume to a larger extent than the normal grinding wear would do. In this paper, the two grinding processes are compared as to their economical efficiency based on a specific machining task. In numerous tests, first, the technological limits of performance were investigated. On the basis of the test results, a time and cost comparison was made. It was found for CD grinding that an optimization of the process parameters led to better results. With a comparable surface quality, higher material removal rates were achieved. On the contrary, the more expensive CBN wheels did not possess a sufficient pore volume to be able to produce comparable results.