A parametric model of cutting temperature generated in end milling process is developed according to the thermal mechanism of end milling as an intermittent operation, which periodically repeats the cycle of heating u...A parametric model of cutting temperature generated in end milling process is developed according to the thermal mechanism of end milling as an intermittent operation, which periodically repeats the cycle of heating under cutting and cooling under non-cutting. It shows that cutting speed and the tool-workpiece engagement condition are determinative for tool temperature in the operation. The suggested model was investigated by tests of AlTiN coated endmill machining hardened die steel JIS SKD61, where cutting temperature on the flank face of tool was measured with an optical fiber type radiation thermometer. Experimental results show that the tendency of cutting temperature to increase with cutting speed and engagement angle is intensified with the progressing tool wear.展开更多
This paper describes the cutting behavior ofa 1 mm thickness acrylic worksheet sheared by a squared punch/die apparatus. In the shearing experiment, a load cell and a high speed camera were used for investigating the ...This paper describes the cutting behavior ofa 1 mm thickness acrylic worksheet sheared by a squared punch/die apparatus. In the shearing experiment, a load cell and a high speed camera were used for investigating the shearing load response and the deformation behavior of the worksheet. It was found that the mechanical parameters, i.e., the punch-die clearance and the feed velocity of the punch, affected the shearing load response, the cracks initiation behavior and the separation capability of the worksheet. Additionally, a FEM （finite element method） analysis simulating a two dimensional shearing deformation was carried out in order to investigate the influence of punch-die clearance on the failure patterns. Through this simulation, it was revealed that the punch-die clearance remarkably affected the tensile state of stress concentrated in the sheared zone and the crack initiation behavior of the worksheet.展开更多
We investigated the reasons for frequently appearing early failure of carbide punches in a progressive stamping die when they were used to produce magnetic shielding steel parts. The failure modes of the carbide punch...We investigated the reasons for frequently appearing early failure of carbide punches in a progressive stamping die when they were used to produce magnetic shielding steel parts. The failure modes of the carbide punches were statistically classified. Edge chipping and shoulder fracturing were the two types of failure modes that were found. The composition, hardness, and microstructure of the punches were analyzed. The cobalt content was found to be too low to ensure sufficient toughness. The brittle phase of tungsten carbide （WC）was prone to breaking off during the shear cutting process, and resulted in edge chipping. In addition, the material chips were easily bonded to the punch edge when there was a lack of press oil lubricity. It resulted in an uneven blanking clearance, which caused a lateral force and finally resulted in shoulder fracturing of the punches. Improvement measures were introduced to address the abovementioned issues. By using the carbide punches with greater toughness and shear cutting oil with high lubricity, the early damage problems of the punches are effectively solved, which ensures normal production of the magnetic shielding steel parts.展开更多
文摘A parametric model of cutting temperature generated in end milling process is developed according to the thermal mechanism of end milling as an intermittent operation, which periodically repeats the cycle of heating under cutting and cooling under non-cutting. It shows that cutting speed and the tool-workpiece engagement condition are determinative for tool temperature in the operation. The suggested model was investigated by tests of AlTiN coated endmill machining hardened die steel JIS SKD61, where cutting temperature on the flank face of tool was measured with an optical fiber type radiation thermometer. Experimental results show that the tendency of cutting temperature to increase with cutting speed and engagement angle is intensified with the progressing tool wear.
文摘This paper describes the cutting behavior ofa 1 mm thickness acrylic worksheet sheared by a squared punch/die apparatus. In the shearing experiment, a load cell and a high speed camera were used for investigating the shearing load response and the deformation behavior of the worksheet. It was found that the mechanical parameters, i.e., the punch-die clearance and the feed velocity of the punch, affected the shearing load response, the cracks initiation behavior and the separation capability of the worksheet. Additionally, a FEM （finite element method） analysis simulating a two dimensional shearing deformation was carried out in order to investigate the influence of punch-die clearance on the failure patterns. Through this simulation, it was revealed that the punch-die clearance remarkably affected the tensile state of stress concentrated in the sheared zone and the crack initiation behavior of the worksheet.
文摘We investigated the reasons for frequently appearing early failure of carbide punches in a progressive stamping die when they were used to produce magnetic shielding steel parts. The failure modes of the carbide punches were statistically classified. Edge chipping and shoulder fracturing were the two types of failure modes that were found. The composition, hardness, and microstructure of the punches were analyzed. The cobalt content was found to be too low to ensure sufficient toughness. The brittle phase of tungsten carbide （WC）was prone to breaking off during the shear cutting process, and resulted in edge chipping. In addition, the material chips were easily bonded to the punch edge when there was a lack of press oil lubricity. It resulted in an uneven blanking clearance, which caused a lateral force and finally resulted in shoulder fracturing of the punches. Improvement measures were introduced to address the abovementioned issues. By using the carbide punches with greater toughness and shear cutting oil with high lubricity, the early damage problems of the punches are effectively solved, which ensures normal production of the magnetic shielding steel parts.
