Ford Motor Company Limited

Richard Ogletree

Daniel M Mills

Thomas J Lindem

Frederick A Sommerhalter, Jr

Kugalur S Chandrasekaran

Charles L Jerzycke

Scott A Martin

Samuel M Mazzara

A fluid bearing assembly for rotatably supporting a rotary-driven spindle having smooth bearing surfaces. Each bearing has a stationary housing holding an annular bearing race that presents a smooth continuous bearing surface facing a complementary bearing surface of the spindle; together the race and spindle define a continuous, thin, uniform crevice space. The smooth race bearing surface is interrupted by a plurality of circumferentially spaced pressure generating zones, each capable of dynamically compressing a fluid body contained in the zone into the crevice in either direction of rotation of the spindle at higher speeds. Pressurized fluid is supplied to flow through each zone and out of the crevice while exerting a predetermined hydrostatic force against the spindle at lower rotational speeds.

Variable speed fluid bearing and method of use

A control system that increases apparent linear motor stiffness and faster frequency for a digital electronic drive of one or more brushless DC linear motors. It comprises a position transducer providing an analog electrical signal indicative of the linear position of a movable part of the linear motor and being induced from an electrical signal supplied to or derived from the motor field winding; a converter for changing the analog signal to an acceleration feedback signal; a processor for providing a position error electrical signal derived by computing the difference between the actual position feedback signal and a position reference signal; and a processor for providing a velocity error electrical signal derived from the difference between the first derivative of the position error electrical signal and the actual velocity feedback signal to produce a velocity command signal, and for providing an acceleration error electrical signal derived from the difference between the second derivative of the position feedback signal and the actual acceleration feedback signal to produce a motor command signal to the field winding of the motor. A method of using such control system comprises providing a positioning apparatus having stacked movable members interconnected by linear motors to promote three-axis movement of a ram acting as the last of said movable members and carrying out the functions of the control for each linear motor.

Linear motor control system and method of use

A method of machining simultaneously a sequence of surfaces on each of multiple sides of a workpiece, comprising: (a) supporting a plurality of rotary-driven spindles, each carrying a cutting tool, each spindle being supported by a plurality of relatively movable elements that provide for movement into and out of a predetermined sized, cubed machining space, such support providing for spindle movement having vectors along at least mutually perpendicular axes; (b) placing the workpiece in the machining space at a predetermined location; (c) actuating relative movement of the elements by use of linear motors to accurately position each spindle for simultaneous machining of first surfaces on separate sides of the workpiece; and (d) actuating the elements by use of said linear motors to reposition the plurality of spindles for simultaneous machining of other surfaces on each of the separate sides of the workpiece.

Method for multiple-spindle machining

A multiple-axis machine for positioning a rotary-driven spindle, such positioning being by use of linear motors. The machine has a support for defining multiple axes, with (i) a rigid vibration-dampening bed defining at least an X-axis; (ii) at least one hollow column defining a Y-axis and having one end adjacent and movable along the bed and the other end extending away from said bed; (iii) a slide adapted for movement along the Y-axis of the column; (iv) a cage rigidly fixed to the slide for defining a Z-axis way; and (v) a hollow ram slidable within the cage and along the Z-axis way and carrying the spindle. The machine has bearing assemblies interposed between the column one end and the bed, between the column and slide, and between the cage and ram to provide for respective relative movements along the axes, the bearing assemblies being preloaded to provide an interference fit of 10-20% of the maximum bearing loading. Linear motor assemblies are interposed between the column one end and bed, between the column and slide, and between the cage and ram, the linear motor assemblies are selectably actuatable to impose a linear thrust force upon any or all of the column, slide, or ram for respective movement along the axes. The ratio of the natural frequency of the support and bearing assemblies to the bandwidth of the control velocity loop is slightly greater than one.

Multi-axis linear motor positioner with Y-axis supported at single end

A machining system that has (i) plural machining cells spaced along a path, each having a single-point-tool and a rapid-positioning assembly for positioning the tool for multiple insertions into a workpiece as well as rapid tool exchange at speed rates that approach or exceed one G; (ii) table means for presenting a table surface in a selected plane for each cell; (iii) workpiece means for each table surface having keying surfaces for lockingly mating with a reference point of such table surface; (iv) transfer means for rapidly replacing a machined workpiece with an unmachined workpiece on a table surface, the just-machined workpiece being transferred to the next table surface while the substituted workpiece is undergoing machining; and (v) programmed electrical control means for activating the positioning assemblies and transfer means. A method of machining, comprising: (a) locking a workpiece on a fixture having dimensional keys and releasably securing such fixture on an adjustable worktable in a predetermined first position facilitated by said keys; (b) adjacent each worktable, rapidly positioning a rotary single-point-tool for linear feed into a first of said workpiece surfaces while in a first position, said positioning being carried out at accelerations/decelerations of at least about one G; (c) feeding the rotating tool into the workpiece to carry out machining at speeds of 1-1300 inches per minute for drilling and boring, and at least about 5000 sfm for milling; (d) after withdrawing the tool from the workpiece, repositioning the single-point-tool for another linear feed into other workpiece surfaces or transfer to another tool.

Multi-positioner machining system

A linear motor assembly having enhanced mechanical stiffness, comprising: (a) at least one pair of rigidly interconnected tandem rails defining a first axis of movement and spaced apart normal to such first axis; (b) at least one pair of frames movable along said pair of rails, each frame presenting at least one pair of opposed parallel bearing surfaces; (c) at least one linear motor effective to operate between each rail and frame; (d) bearings supported between each rail and each bearing surface of each frame, said bearings being preloaded with an interference load while permitting bearing movement; and (e) support structure between said frames defining axes of movement actuated by other linear motors.

High-force linear motor assembly using tandem axes

A machining system that has (i) plural machining cells spaced along a path, each having a single-point-tool and a rapid-positioning assembly for positioning the tool for multiple insertions into a workpiece as well as rapid tool exchange at speed rates that approach or exceed one G; (ii) table means for presenting a table surface in a selected plane for each cell; (iii) workpiece means for each table surface having keying surfaces for lockingly mating with a reference point of such table surface; (iv) transfer means for rapidly replacing a machined workpiece with an unmachined workpiece on a table surface, the just-machined workpiece being transferred to the next table surface while the substituted workpiece is undergoing machining; and (v) programmed electrical control means for activating the positioning assemblies and transfer means.

Positioning apparatus for multiple-spindle machining, comprising: (a) a plurality of upstanding columns rigidly interconnected to a common platform and aligned parallel to each other and perpendicular to the platform within an accuracy of .+-.0.0005 inches; (b) rail means extending between each of the columns along the periphery defined by the footprint of the columns for providing movable support and having bearing means on the columns providing for movement of each rail means along the Y-axis; (c) other movement means slidable on each of the rail means along at least another axis of movement; (d) linear motor means for selectively moving the rail means and other movement means along said respective Y and another axis at peak accelerations or decelerations of about 1-2 G's; and (d) spindle means on each ram having a spindle rotationally driven about an S-axis thereof.

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Southfield, MI, United States of America

Richard Ogletree