US 4,370,721 A · Method for modifying programmed positions by using a programmably controlled surface sensing element

Abstract

A method is disclosed for modifying coordinate data in a machining program in response to workpiece measurements made by a programmably controlled surface sensing element. The location of the workpiece and position of workpiece characteristics are determined by a series of programmed scanning cycles. The maximum, minimum and average measured positions of points on a workpiece surface are stored and may be used to calculate position offsets which may be used to modify a machining program. Further, the measured positions and offsets may be tested against programmed maximum and minimum limits to determine if the measured positions are within a tolerance band. In one embodiment, the positions of points on the workpiece surface are measured by a cutting tool operating in conjunction with a torque measuring circuit.

Claims51

Dependent claims

A method for measuring the actual position of unmachined surfaces on a workpiece and modifying command signals derived from a machining program defining a cycle of operation of a machine relative to the unmachined surfaces, said machine having machine slides moving along axes of motion for effecting relative movement between the workpiece and a tool holder having a sensing element associated therewith, said machine being connected to a control for storing the machining program and generating the command signals to control the relative motion, the method comprising the steps of:

(a) storing scanning program instructions in association with the machining program to define a scanning cycle for using the sensing element to measure the actual position of the unmachined surfaces;
(b) executing the scanning cycle prior to executing the cycle of operation in response to the scanning program instructions to generate coordinate signals representing positions of detected points on the unmachined surfaces;
(c) storing selected ones of the coordinate signals;
and
(d) executing the cycle of operation after completing the scanning cycle by generating modified command signals in response to the selected coordinate signals and the command signals derived from the machining program, said modified command signals effecting relative motion between the tool holder and the workpiece in accordance with the machining program and independent of variations in the position of the unmachined surfaces.

2 more elements

A method for measuring the actual position of an unmachined planar surface on a workpiece and modifying command signals derived from a machining program defining the operation of a machine, said machine having machine slides moving along axes of motion for effecting relative movement between the workpiece and a tool holder having a sensing element associated therewith, said machine being connected to a control for storing the machining program and generating the command signals to control the relative motion, the method comprising the steps of:

(a) storing scanning program instructions in association with the machining program to define a scanning cycle for using the sensing element to measure the actual position of a plurality of points on the planar surface;
(b) executing the scanning cycle in response to the scanning program instructions to generate coordinate signals representing the plurality of points on the planar surface;
(c) storing a number of the coordinate signals;
and
(d) generating modified command signals in response to the stored coordinate signals and the command signals derived from the machining program, said modified command signals effecting relative motion between the tool holder and the workpiece in accordance with the machining program and independent of variations in the position of the planar surface.

2 more elements

A method for measuring the actual position of an unmachined planar surface on a workpiece and modifying command signals derived from a machining program defining the operation of a machine, the machining program containing a reference coordinate value representing a predetermined point on the workpiece, and said machine having machine slides moving along axes of motion for effecting relative movement between the workpiece and a toolholder having a sensing element associated therewith, the machine being connected to a control for storing the machining program and generating the command signal to control the relative motion, the method comprising the steps of:

(a) storing a scanning program in association with the machining program to define a scanning cycle for using the sensing element to measure the actual position of a plurality of points on the planar surface;
(b) generating in response to the scanning program scanning command signals to position the sensing element opposite a point on the planar surface;
(c) generating further scanning command signals to cause the sensing element to move along an axis of motion toward the planar surface;
(d) terminating the motion of the sensing element in response to the sensing element detecting a point on the planar surface;
(e) producing a coordinate signal defining the position of the detected point along the axis of motion;
(f) generating an offset signal as a function of the coordinate signal and the reference coordinate value;
(g) storing the offset signal;
(h) iterating steps (b) through (g) a predetermined number of times defined by the scanning program to measure the position of a number of different points on the planar surface;
and
(i) generating modified command signals in response to the offset signals and the command signals derived from the machining program, said modified command signals effecting relative motion between the tool holder and the planar surface in accordance with the machining program.

7 more elements

A method for measuring the actual position of workpiece surfaces and modifying command signals derived from a machining program defining the operation of a machine, said machine having machine slides moving along axes of motion for effecting relative motion between the workpiece and a tool holder having a cutting tool associated therewith, said machine being connected to a control for storing the machining program and generating command signals to control the relative motion, said control including a torque measuring circuit responsive to the cutting tool for producing a contact signal in response to cutting forces imposed on the tool being at least equal to a predetermined torque limit representing superficial contact of the cutting tool on the workpiece, the method comprising the steps of:

(a) storing scanning program instructions in association with the machining program to define a scanning cycle for measuring the actual position of a surface of a workpiece;
(b) generating in response to the scanning program instructions first command signals to move the cutting tool along one axis of motion towards a point on the surface;
(c) terminating the motion of the cutting tool in response to the contact signal;
(d) generating a coordinate signal representing the position of the point on the surface in response to the contact signal;
(e) generating a second command signal in response to the coordinate signal to move the tool away from the workpiece;
(f) iterating steps (b) through (e) to produce a number of coordinate signals representing the position of a plurality of points on the surface;
(g) storing selected coordinate signals;
and
(h) generating modified command signals in response to the stored coordinate signal and the command signals derived from the machining program, said modified command signals effecting relative motion between the cutting tool and the workpiece in accordance with the machining program and independent of variations in the position of the surface.

6 more elements

A method for modifying slide position command signals derived from a machining program defining the operation of a machine with respect to a program coordinate system, the machine having slides moving along axes of motion defining a mutually perpendicular triordinate machine coordinate system for effecting relative motion between a workpiece and a tool holder having a sensing element associated therewith, the sensing element comprising a cutting tool and the control including a torque measuring circuit for generating a contact signal in response to cutting torque being at least equal to a torque limit representing a superficial contact between the tool and workpiece, the machine being connected to a control for storing the machining program and generating slide position command signals in response thereto to control the relative motion, the method comprising the steps of:

(a) storing workpiece locating instructions in association with the machining program;
(b) executing the workpiece locating instructions to use the sensing element to generate translated current slide position signals representing current slide positions translated with respect to the machine coordinate system;
and
(c) generating modified slide position command signals in response to the translated current slide position signals and the machining program, thereby effecting translation of the program coordinate system with respect to the machine coordinate system.

1 more element

Dependencies are inferred from the claim text.

Method for modifying programmed positions by using a programmably controlled surface sensing element

Life of this patent

Method for modifying programmed positions by using a programmably controlled surface sensing element

Life of this patent

Abstract

Claims51