The miniaturisation context leads to the rise of micro-machining processes. Micro-milling is one of the most flexible and fast of them. Although it is based on the same principles as macro-cutting, it is not a simple ...The miniaturisation context leads to the rise of micro-machining processes. Micro-milling is one of the most flexible and fast of them. Although it is based on the same principles as macro-cutting, it is not a simple scaling-down of it. This down-sizing involves new phenomena in the chip formation, such as the minimum chip thickness below which no chip is formed. This paper presents a review of the current state of the art in this field from an experimental and a numerical point of view. A 2D finite element model is then developed to study the influence of the depth of cut on the chip formation. After the model validation in macro-cutting, it highlights the phenomena reported in literature and allows to perform a minimum chip thickness estimation.展开更多
Titanium alloys are widely used in the aviation and aerospace industries due to their unique mechanical and physical properties.Specifically,thin-walled titanium(Ti)cylinders have received increasing attention for the...Titanium alloys are widely used in the aviation and aerospace industries due to their unique mechanical and physical properties.Specifically,thin-walled titanium(Ti)cylinders have received increasing attention for their applications as rocket engine casings,aircraft landing gear,and aero-engine hollow shaft due to their observed improvement in the thrust-to-weight ratio.However,the conventional cutting(CC)process is not appropriate for thin-walled Ti cylinders due to its low thermal conductivity,high strength,and low stiffness.Instead,high-speed ultrasonic vibration cutting(HUVC)assisted processing has recently proved highly effective for Ti-alloy machining.In this study,HUVC technology is employed to perform external turning of a thinwalled Ti cylinder,which represents a new application of HUVC.First,the kinematics,tool path,and dynamic cutting thickness of HUVC are evaluated.Second,the phenomenon of mode-coupling chatter is analyzed to determine the effects and mechanism of HUVC by establishing a critical cutting thickness model.HUVC can increase the critical cutting thickness and effectively reduce the average cutting force,thus reducing the energy intake of the system.Finally,comparison experiments are conducted between HUVC and CC processes.The results indicate that the diameter error rate is 10%or less for HUVC and 51%for the CC method due to a 40%reduction in the cutting force.In addition,higher machining precision and better surface roughness are achieved during thin-walled Ti cylinder manufacturing using HUVC.展开更多
文摘The miniaturisation context leads to the rise of micro-machining processes. Micro-milling is one of the most flexible and fast of them. Although it is based on the same principles as macro-cutting, it is not a simple scaling-down of it. This down-sizing involves new phenomena in the chip formation, such as the minimum chip thickness below which no chip is formed. This paper presents a review of the current state of the art in this field from an experimental and a numerical point of view. A 2D finite element model is then developed to study the influence of the depth of cut on the chip formation. After the model validation in macro-cutting, it highlights the phenomena reported in literature and allows to perform a minimum chip thickness estimation.
基金supported by the Defense Industrial Technology Development Program of China(No.JCKY2018601C209)。
文摘Titanium alloys are widely used in the aviation and aerospace industries due to their unique mechanical and physical properties.Specifically,thin-walled titanium(Ti)cylinders have received increasing attention for their applications as rocket engine casings,aircraft landing gear,and aero-engine hollow shaft due to their observed improvement in the thrust-to-weight ratio.However,the conventional cutting(CC)process is not appropriate for thin-walled Ti cylinders due to its low thermal conductivity,high strength,and low stiffness.Instead,high-speed ultrasonic vibration cutting(HUVC)assisted processing has recently proved highly effective for Ti-alloy machining.In this study,HUVC technology is employed to perform external turning of a thinwalled Ti cylinder,which represents a new application of HUVC.First,the kinematics,tool path,and dynamic cutting thickness of HUVC are evaluated.Second,the phenomenon of mode-coupling chatter is analyzed to determine the effects and mechanism of HUVC by establishing a critical cutting thickness model.HUVC can increase the critical cutting thickness and effectively reduce the average cutting force,thus reducing the energy intake of the system.Finally,comparison experiments are conducted between HUVC and CC processes.The results indicate that the diameter error rate is 10%or less for HUVC and 51%for the CC method due to a 40%reduction in the cutting force.In addition,higher machining precision and better surface roughness are achieved during thin-walled Ti cylinder manufacturing using HUVC.
