Binary inspection probe for numerically controlled machine tools

• US 4,118,871 A
• Filed: 06/13/1978
• Issued: 10/10/1978
• Est. Priority Date: 06/13/1978
• Status: Expired due to Term

• Current Assignee: Kearney & Trecker Corp. (Maxcor, Inc.)
• Original Assignee: Kearney & Trecker Corp. (Maxcor, Inc.)
• Inventors: Kirkham, Edward E.
• Primary Examiner(s): Stearns, Richard R.
• Application Number:
  US05/805,914
• Time in Patent Office: 119 Days
• Field of Search: 33/172 E, 33/174 L, 33/174 PC, 235/92 MP, 235/92 MT, 235/151.3, 235/151.32, 318/16, 318/574, 364/560, 364/563
• US Class Current: 33/505
• CPC Class Codes: G01B 7/008 using coordinate measuring machines

Abstract

An inspection probe is mounted in the spindle of a numerically controlled machine tool and is moved toward a workpiece therein by the numerical controls until it makes contact with the workpiece. Contact with the workpiece is indicated by change in the output signal of a portable transmitter mounted within the toolholder that carries the inspection probe. The change in output amplitude causes the instantaneous position of the spindle to be recorded in the numerical controls at the instant of contact between the inspection probe and workpiece to indicate the corresponding dimension of the workpiece. Movement of the spindle is stopped after contact between the inspection probe and workpiece to avoid damage to either the inspection probe or the workpiece.

Claims

1. A method of measuring a dimension of a workpiece in a numerically controlled machine tool, said machine tool including a workpiece holder for holding said workpiece;

means including a detachably mounted toolholder for holding a tool in a position to perform work on said workpiece;

numerical control means for varying the relative position of said workpiece holder and toolholder means in response to digital input signals; and

position feedback means indicating the position of said workpiece holder and toolholder means with respect to a machine reference point, said method comprising the steps of;

(1) mounting a toolholder including an inspection probe in said toolholder means;

(2) causing relative motion between said toolholder means and said workpiece holder in the direction of decreasing the distance between said workpiece and inspection probe;

(3) stopping relative movement of said toolholder means and workpiece holder after said inspection probe makes contact with said workpiece;

(4) causing relative motion between said toolholder means and said workpiece holder in the direction of separating said workpiece and inspection probe; and

(5) recording the position of said workpiece and toolholder means as indicated by the output of said position feedback means at the instant said inspection probe breaks contact with said workpiece.

2. Apparatus for measuring a dimension of a workpiece in a numerically controlled machine tool including means for detachably mounting a toolholder, said measuring apparatus comprising:

a workpiece holder for holding said workpiece;

means including a measuring toolholder mounted in said mounting means for holding a tool including a probe element in a position to perform measurements on said workpiece;

numerical control means for varying the relative position of said workpiece holder and toolholder means in response to digital input signals;

position feedback means for indicating the position of said workpiece and toolholder means with respect to a machine reference point;

a radio transmitter mounted within said toolholder and being operatively connected to said probe element for producing an electromagnetic output, said output changing in response to said probe element contacting said workpiece;

means for radiating the electromagnetic output of said radio transmitter;

a radio receiver for receiving the electromagnetic radiation from said probe element, the output of said radio receiver being coupled to said numerical control means; and

means in said numerical control means for recording the position of said workpiece and toolholder means as indicated by the output of said position feedback means at the instant said probe element makes contact with said workpiece, the recorded positions of said workpiece and toolholder means being a measure of a corresponding dimension of said workpiece.

3. The measurement apparatus according to claim 2 wherein said probe element is coupled to the output of said radio transmitter and acts as the means for radiating the electromagnetic output of said radio transmitter.