Tool abnormality determination system

Patent metadata

Field	Value
Publication number	US-10359356-B2
Application number	US-201414189564-A
Country	US
Kind code	B2
Filing date	Feb 25, 2014
Priority date	Mar 6, 2013
Publication date	Jul 23, 2019
Grant date	Jul 23, 2019

Abstract

A tool abnormality detection system corrects a monitoring range for a load on a tool in an M th cycle by using load data of at least one of 1 st to (M−1) th cycles (where M is an integer of 2 or more), wherein processing work on a single workpiece corresponds to a single cycle, and the load data is data about the load on the tool in the cycle.

First claim

What is claimed is:

1. A tool abnormality determination system for detecting abnormalities in a tool according to a state of the tool, by automatically and continuously performing correction of a monitoring range for detecting the abnormalities, the tool abnormality determination system comprising:
a processor;
a display; and
at least one motor drive circuit connected to a respective at least one motor, the at least one motor drive circuit driving the at least one motor so as to process work by a tool on a workpiece, wherein
the processor is configured to:
set an offset amount;
detect load data of the at least one motor at predetermined intervals; and
use the load data of at least one of 1 st to (M−1) th cycles to correct a monitoring range for a load on the tool in an M th cycle (where M is an integer of 2 or more),

the monitoring range is a difference between: (i) a first current value, which is an upper limit threshold at a given time in a first cycle; and (ii) a second current value, which is a lower limit threshold at the given time in a second cycle, the first current value and the second current value being peak current values,
the lower limit threshold is determined by using the offset amount to correct a low load-side peak hold value, and the upper limit threshold is determined by using the offset amount to correct a high load-side peak hold value,
processing the work on the workpiece by using the tool corresponds to a single cycle,
the load data is an indicator of the load on the tool in the single cycle,
the load data includes a plurality of current values,
when a current value, of the plurality of current values, is out of the monitoring range, the processor is further configured to count a number of consecutive times the current value is out of the monitoring range,
when the number of consecutive times does not exceed a number-of-consecutive-times threshold, the processor is further configured to continue to monitor the current value, and
when the number of consecutive times exceeds the number-of-consecutive-times threshold, the processor is further configured to stop processing the work on the workpiece as soon as the current value is out of the monitoring range and display guidance on the display, the guidance prompting a user to confirm whether or not the tool is actually in an abnormal state.

2. The tool abnormality determination system according to claim 1 , wherein the processor is further configured to:
perform an air-cut step of moving the tool so as to bring the tool into contact with the workpiece; and
perform an actual processing step of processing the workpiece by using the tool,
wherein the air-cut step and the actual processing step are performed during the cycle, and the actual processing step is performed after the air-cut step,
wherein a plurality of pieces of the load data which are detected in or before the air-cut step in the M th cycle have early-stage data including at least one piece of the load data, and later-stage data including at least one piece of the load data which is detected later than the load data detected last in the early-stage data, and
wherein the processor is further configured to:
use a load ratio between the early-stage data and the later-stage data to correct the monitoring range in the actual processing step of the M th cycle.

3. The tool abnormality determination system according to claim 2 , wherein the processor is further configured to:
perform a teaching process which includes at least one of the cycles, and setting the monitoring range by using the load data detected in the at least one of the cycles; and
perform a processing process which includes at least one of the cycles, and processing the workpiece while monitoring the load on the tool by using the monitoring range, and
wherein the early-stage data is detected in the cycle of the teaching process.

4. The tool abnormality determination system according to claim 3 , wherein the processor is further configured to:
perform the air-cut step in the cycle of the teaching process, the air-cut step performed in the cycle of the teaching process being a first air-cut step;
detect the early-stage data in the first air-cut step;
perform the air-cut step in the cycle of the processing process, the air-cut step performed in the cycle of the processing process being a second air-cut step; and
detect the later-stage data in the second air-cut step.

5. The tool abnormality determination system according to claim 3 , wherein the processor is further configured to:
perform the actual processing step in the cycle of the teaching process, the actual processing step performed in the cycle of the teaching process being a first actual processing step;
detect the early-stage data in the first actual processing step;
perform the actual processing step in the cycle of the processing process, the actual processing step performed in the cycle of the processing process being a second actual processing step; and
detect the later-stage data in the second actual processing step in the cycle of the processing process.

6. The tool abnormality determination system according to claim 5 , wherein the processor is further configured to:
detect the later-stage data in the actual processing step in the (M−1) th cycle.

7. The tool abnormality determination system according to claim 5 , wherein the processor further configured to:
detect the later-stage data in the actual processing steps in a plurality of the cycles including the (M−1) th cycle.

Assignees

• Fuji Machine Mfg

Inventors

• Kumazaki Shinya
• Furukawa Kazuya

Classifications

• G01N19/08 Primary

  Detecting presence of flaws or irregularities · CPC title

• G05B2219/34464

  Adaptive threshold, level for alarm, eliminate false alarm · CPC title

• G05B2219/37076

  Display load on tool, motor graphically on screen · CPC title

• B23Q17/0961

  by measuring power, current or torque of a motor · CPC title

• G01N3/58 Primary

  Investigating machinability by cutting tools; Investigating the cutting ability of tools · CPC title