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US 4,653,360 AGranted
CNC turning machine
AssigneeThe Cross Company
InventorRonald E. Compton
Life of this patent
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AssigneeThe Cross Company
InventorRonald E. Compton
Estimating the term…
A turning machine is characterized by a new and improved control and mechanism for positioning the turning tool on the head. A CNC control issues command signals for selectively positioning the tool on the head. These signals are developed from an encoder which provides the instantaneous position of the rotating part being turned and from a program in the CNC containing information about the part. A closed loop control system receives these command signals and converts same into a control current for a linear motor which is the prime mover controlling the positioning of the tool on the head. The linear motor operates a carriage on the head and the cutting tool mounts on the carriage opposite the connection of the linear motor to the carriage. The carriage is a hollow bar guided on the head by sets of rollers which are cooperatively arranged to provide yieldably forceful constraint of the bar. The rolling action of the bar on the head provides a low friction, low inertia construction enabling rapid response to CNC commands. The head also contains various sensors providing position and velocity feedback information for use by the closed loop control. The closed loop control contains various circuit components organized and arranged to provide fast and faithful response to command signals. The machine has the ability to accurately turn complex parts where position information is being rapidly updated, often in the tens of kilohertz frequency range. Different parts can be turned by merely changing the CNC program.
In a turning machine (40) comprising means for rotating (48) a part (42) about an axis (44) and for causing a cutting tool (56) to make an axial pass along the part while the radial position of the tool relative to the part is selectively controlled in correlation with the angular position of the part about the axis of rotation as the part is being rotated, the improvement which comprises a main CNC control (58), angular position sensing means (54) operatively coupled with said means for rotating the part to provide to the CNC control information representative of instantaneous angular position of the part about the axis for rotation as the part is being rotated, radial position sensing means (74) for sensing the radial position of the cutting tool relative to the part, radial velocity sensing means (76) for sensing the radial velocity of the tool relative to the part, and a closed loop control system (80) for closed loop controlling the radial position of the cutting tool relative to the part as a function of the radial position of the cutting tool and the radial velocity of the cutting tool, said closed loop control system comprising an electric linear motor (72) as the prime mover for radially positioning the cutting tool, said CNC comprising means for issuing commands to the closed loop control system correlated with the information with said position sensing means and information about the part, and said closed loop control system comprising means for converting the CNC commands into a corresponding control current for the linear motor.
In a turning machine comprising means for rotating a part about an axis and for causing a cutting tool to make an axial pass along the part while the radial position of the tool relative to the part is selectively controlled in correlation with the angular position of the part about the axis of rotation as the part is being rotated, the improvement which comprises a main CNC control, position sensing means operatively coupled with said means for rotating the part to provide to the CNC control information representative of instantaneous angular position of the part about the axis of rotation as the part is being rotated, radial position sensing means for sensing the radial position of the cutting tool relative to the part, radial velocity sensing means for sensing the radial velocity of the tool relative to the part, and a closed loop control system for closed loop controlling the radial position of the cutting tool relative to the part as a function of the radial position of the cutting tool and the radial velocity of the cutting tool, said closed loop control system comprising an electric linear motor for radially positioning the cutting tool, said CNC comprising means for issuing commands to the closed loop control system correlated with information from said position sensing means and information about the part, and said closed loop control system comprising means for converting the CNC commands into a corresponding control signal for the linear motor and wherein said tool is mounted on a carriage which is guided by guide means on a head with the carriage being operatively coupled with the linear motor so as to be selectively positionable along a line of travel on the head in accordance with operation of the linear motor by the control signal developed from the CNC commands, said carriage comprising a hollow bar having an exterior surface which in transverse cross section is polygonal and in which said guide means comprises a plural sets of rollers providing rolling contact with the exterior surface of said hollow bar as said hollow bar is operated by said linear motor and in which at least one set of rollers comprises plural non-yieldably mounted rollers and plural yieldably mounted rollers, such yieldably and non-yieldably mounted rollers coacting with respective exterior surface portions of said hollow bar to provide for yieldablr forceful constraint of the hollow bar while allowing the bar to be rolled thereon.
In a turning machine having a head on which a tool is selectively positionable toward and away from a workpiece by a prime mover and a carriage an improved prime mover and carriage combination for selectively positioning the tool on the head characterized by low friction, low inertia, and rapid response to input commands and comprising an electric linear motor forming the prime mover and a bar forming the carriage, said bar having plural exterior surface portions via which the bar rolls on coacting sets of rollers on the head, said coacting sets of rollers being arranged to constrain to bar to motion along a line of travel toward and away from the part while applying yieldably forceful engagement of the bar, and wherein the bar is further defined to have a rectangular exterior cross sectional shape so that said plural exterior surface portions comprise two pairs of parallel surfaces with the two pairs being 90.degree. apart about the axis of the bar, and in which for each pair of parallel surfaces there is a corresponding coacting set of rollers, each coacting set comprising a set of plural non-yieldably mounted rollers and a set of plural yieldably mounted rollers.
A method of controlling the radial position of a tool relative to the rotational axis of a workpiece in a turning cperation whrein the surface geometry of the workpiece is defined by a data matrix of axial, angular and radial position coordinates, said method comprising the steps of:
A system for controlling the radial position of a tool relative to the rotational axis of a workpiece whrein the surface geometry of the workpiece is defined by a data matrix of axial, angular and radial position coordinates, the system comprising:
In combination with a machine tool (40) of the type having a spindle (48) for rotating a workpiece (42) to be machined, a cutting head (56), an electric linear motor (72) for moving the cutting head (56) radially relative to the spindle axis (44), control means for producing an output signal for controlling the linear motor to machine the workpiece to have a configuration that is defined by a stored part program, said control means including means (54) for sensing the angular position of said spindle, means (66) for sensing the axial position of said cutting head and means (74) for sensing the radial position of said cutting head, the improvement characterized in that:
An improved machine tool (40) of the type having a spindle (48) for rotating a workpiece (42) to be machined, a cutting head (56), an electric linear motor (72) for moving the cutting head radially relative to the spindle axis (44) to machine the workpiece to have configuration that is defined by a stored part program, said linear motor being controlled by closed loop control system (80) responsive to the radial position of the cutting head as derived from radial position sensing means (74) and the radial velocity of the cutting head as derived from radial velocity sending means (76), the improvement characterized in that:
In combination with a machine tool (40) of the type including a spindle (48) for rotating a workpiece (42) to be machined about a spindle axis (44), a cutting head (56), an electric linear motor (72) responsive to a control signal for moving the cutting head (56) radially relative to said spindle axis (44), and control means (80, 58, 54, 66, 74) for providing a control signal to the electric linear motor to machine the workpiece to have a configuration defined by a stored part program, said control means including angular position sensing means (54) for sensing the angular position of the workpiece (42) about the spindle axis (44), axial position sensing means (66) for sensing the axial position of the cutting head (56) along the spindle axis (44), and radial position sensing means (74) for sensing the radial position of said cutting head (56) relative to said spindle axis (44) to develop the control signal as a function of the sensed angular, axial and radial positions, the improvement characterized in that:
Dependencies are inferred from the claim text.