Evaluation of Noncoated Carbide Drill with Sharp Cutting Edge and Multistage Point Angle for Drilling of Carbon Fiber Reinforced Thermoplastics
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This paper presents the application of a noncoated carbide drill having a sharp cutting edge and multistage point angle (drill A) for drilling carbon fiber reinforced thermoplastics (CFRTP). The cutting characteristics were evaluated by comparing the drill A with a diamond-coated carbide drill having a constant point angle (drill B). The influence of the contact state between the cutting edge and carbon fiber on the cutting force was evaluated using a CFRTP with a unidirectional fiber. The drill A exhibited a maximum thrust force at the drill rotation angle where the fiber orientation and cutting edge travel direction matched. It was found that the thrust force of the drill A was lower than that of the drill B at any drill rotation angle. Moreover, the thrust force of the drill A was always lower than that of the drill B during the drilling of the CFRTP with a plain-woven fabric. Additionally, the uncut fiber of the drilled hole obtained by the drill A was more satisfactory than that obtained by the drill B. The temperature of the area near the cutting point during the drilling was lower in the drill A than in the drill B. In the drill A, the thrust force tended to increase with the number of drilled holes. However, no considerable reduction in the drilled hole quality was observed at 200 holes.The paper introduces rock drilling in slope level with KQX120 Cutting DTH drill about itsprinciple, method, manufacture of drilling tool and effect. Contrasting with retrofittedgeological probe drilling facilities, the result shows that the construction cost is lower andeffect is better with KQX120 drill
Measurement while drilling
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It is very important for drilling parameters test to better drilling parameters,design drill rig,research on drilling technology.According to the structure and operating principle of the JSL-30 drill rig,a drill parameter tester was developed especially for percussion drill.The test datu of drilling parameters is accurate by practice.
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The purpose of this study is to investigate effectiveness of thrust force for estimation of burr occurred at outlet of drilled hole and the prefailure phase of micro drills in drilling holes through thin stainless steel plate (JIS SUS304). Micro drilling tests, in which feed rate, step feed length, and diameter of micro drill are adopted as experimental parameters, were carried out to measure thrust force during drilling operations. On the other hand, tool wear of cutting edge and burr occurred at outlet of drilled hole were measured at intervals of constant number of drilled holes to consider their relationship to thrust force. As a result of some considerations, thrust force during micro drilling can be related with height of burr occurred at outlet of drilled hole and prefailur phase of micro dills.
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This paper presents the application of a noncoated carbide drill having a sharp cutting edge and multistage point angle (drill A) for drilling carbon fiber reinforced thermoplastics (CFRTP). The cutting characteristics were evaluated by comparing the drill A with a diamond-coated carbide drill having a constant point angle (drill B). The influence of the contact state between the cutting edge and carbon fiber on the cutting force was evaluated using a CFRTP with a unidirectional fiber. The drill A exhibited a maximum thrust force at the drill rotation angle where the fiber orientation and cutting edge travel direction matched. It was found that the thrust force of the drill A was lower than that of the drill B at any drill rotation angle. Moreover, the thrust force of the drill A was always lower than that of the drill B during the drilling of the CFRTP with a plain-woven fabric. Additionally, the uncut fiber of the drilled hole obtained by the drill A was more satisfactory than that obtained by the drill B. The temperature of the area near the cutting point during the drilling was lower in the drill A than in the drill B. In the drill A, the thrust force tended to increase with the number of drilled holes. However, no considerable reduction in the drilled hole quality was observed at 200 holes.
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The accuracy of drill hole location is critical for implant placement in orthopaedic surgery. Increasing drill bit size sequentially has been suggested as a method for improving the accuracy of drill hole start location. The aim of this study was to determine whether sequential drilling or drill angulation would alter accuracy of drill hole start location. Three specialist veterinary surgeons drilled holes in synthetic bone models either directly, or with sequentially increasing drill bit sizes. Drilling was performed at 0 o , 10 o and 20 o to perpendicular to the bone models. Three synthetic bone models were used to mimic canine cancellous and cortical bones. Sequential drilling resulted in greater inaccuracy in drill hole location when assessing all drilling angles together. There was no influence of surgeon or synthetic bone density on drilling accuracy. The combination of drill angulation and sequential drilling increased inaccuracy in drill hole start location. We conclude that sequential drilling decreased accuracy of drill hole location in the synthetic bone model when drilling was angled. Inaccuracy associated with the drill hole start location should be taken into account when performing surgery, although the magnitude of inaccuracy is low when compared with other sources of error such as angulation.
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In recent years, needs for micro drilling are increasing, accompanying the development of higher wiring density of printed circuit board (PCB). When drilling PCB for the purpose of making the electric through holes, it has been said that the drill breakage is caused by being filled the chips of GFRP and copper of PCB in the drill flutes. The aim of this study is to clarify the effect of PCB drilling using DLC coated drill on tool wear, chip evacuation and cutting torque. Series of drilling tests of PCB have been carried out to investigate the amount of drill wear, the chips evacuation behavior out of drilled hole with the drill, the shape of chips produced and the cutting torque using DLC-coated drill and non-coated drill. The chips evacuation behavior out of drilled hole with the drill is filmed by a high-speed motion camera and the shape of chips produced is observed by a microscope. The cutting torque is measured by a dynamometer; Kistler 9329A. The amounts of drill flank wear and margin wear using DLC-coated drill and non-coated drill are almost the same. The chips of GFRP using DLC-coated drill are shorter and smaller than those using non-coated drill. The chips evacuation out of drilled hole with the drill using DLC-coated drill is better than those using non-coated drill, and cutting torque using DLC-coated drill is lower than those using non-coated drill.
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