Method and apparatus for suppressing regenerative instability and related chatter in machine tools
First Claim
1. A method for controlling chatter in a machine tool assembly during a machining operation, the machine tool assembly having a plurality of components, the plurality of components comprising a variable compliant component made with a material having a variable compliance, the plurality of components having a mechanical impedance, the method comprising the step of modulating the mechanical impedance of at least one of the plurality of components, wherein the machine tool assembly further comprises a chuck, the chuck in mechanical communication with the variable compliant component, wherein the step of modulating the mechanical impedance comprises modulating the resonant frequency of the plurality of components by changing the variable compliance of the variable compliant component to mitigate regenerative chatter vibrations.
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Accused Products
Abstract
Methods of and apparatuses for mitigating chatter vibrations in machine tools or components thereof. Chatter therein is suppressed by periodically or continuously varying the stiffness of the cutting tool (or some component of the cutting tool), and hence the resonant frequency of the cutting tool (or some component thereof). The varying of resonant frequency of the cutting tool can be accomplished by modulating the stiffness of the cutting tool, the cutting tool holder, or any other component of the support for the cutting tool. By periodically altering the impedance of the cutting tool assembly, chatter is mitigated. In one embodiment, a cyclic electric (or magnetic) field is applied to the spindle quill which contains an electro-rheological (or magneto-rheological) fluid. The variable yield stress in the fluid affects the coupling of the spindle to the machine tool structure, changing the natural frequency of oscillation. Altering the modal characteristics in this fashion disrupts the modulation of current tool vibrations with previous tool vibrations recorded on the workpiece surface.
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Citations
18 Claims
- 1. A method for controlling chatter in a machine tool assembly during a machining operation, the machine tool assembly having a plurality of components, the plurality of components comprising a variable compliant component made with a material having a variable compliance, the plurality of components having a mechanical impedance, the method comprising the step of modulating the mechanical impedance of at least one of the plurality of components, wherein the machine tool assembly further comprises a chuck, the chuck in mechanical communication with the variable compliant component, wherein the step of modulating the mechanical impedance comprises modulating the resonant frequency of the plurality of components by changing the variable compliance of the variable compliant component to mitigate regenerative chatter vibrations.
- 7. A method for controlling chatter in a machine tool assembly during a machining operation, the machine tool assembly having a plurality of components, the plurality of components having a mechanical impedance, the method comprising the step of modulating the mechanical impedance of at least one of the plurality of components to mitigate regenerative chatter vibrations, wherein the step of modulating the mechanical impedance further comprises the step of using a chuck and means for modulating the resonant frequency of the plurality of components, the means having a variable compliance.
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16. A method for controlling chatter in a machine tool assembly during a machining operation, the machine tool assembly having a plurality of components, the plurality of components having a mechanical impedance, the method comprising the step of modulating the mechanical impedance of at least one of the plurality of components, wherein the step of modulating the mechanical impedance further comprises modulating the resonant frequency of the plurality of components to mitigate regenerative chatter vibrations, wherein the at least one of the plurality of components comprises a cutting tool, and wherein at least one of the plurality of components is a machine tool support adapted to receive the cutting tool, wherein the step of modulating the mechanical impedance further comprises the step of providing a signal to the cutting tool, the signal having a square wave form.
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17. A method for controlling chatter in a machine tool assembly during a machining operation, the machine tool assembly having a plurality of components, the plurality of components having a mechanical impedance, the method comprising the step of modulating the mechanical impedance of at least one of the plurality of components, wherein the step of modulating the mechanical impedance further comprises modulating the resonant frequency of the plurality of components to mitigate regenerative chatter vibrations, wherein the at least one of the plurality of components comprises a cutting tool, and wherein at least one of the plurality of components is a machine tool support adapted to receive the cutting tool, wherein the step of modulating the mechanical impedance further comprises the step of subjecting the cutting tool to a field, the cutting tool having at least one blade, the field being characterized by a sinusoidal form.
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18. A method for controlling chatter in a machine tool assembly during a machining operation, the machine tool assembly having a plurality of components, the plurality of components having a mechanical impedance, the method comprising the step of modulating the mechanical impedance of at least one of the plurality of components, wherein the step of modulating the mechanical impedance further comprises modulating the resonant frequency of the plurality of components to mitigate regenerative chatter vibrations, wherein the at least one of the plurality of components comprises a cutting tool, wherein the step of modulating the mechanical impedance further comprises the step of providing a random signal to the cutting tool.
Specification