Optical safety device, press brake, and workpiece detection method

Patent metadata

Field	Value
Publication number	US-11980926-B2
Application number	US-201917417142-A
Country	US
Kind code	B2
Filing date	Dec 16, 2019
Priority date	Dec 25, 2018
Publication date	May 14, 2024
Grant date	May 14, 2024

Abstract

A received beam amount acquisition section 60 acquires a received beam amount per unit time of a beam receiver 52 at certain sampling time intervals. A beam shielding detection section 66 detects presence or absence of beam shielding of a monitoring beam B by determining whether or not the acquired received beam amount per unit time of the beam receiver is lower than a determination threshold Th for detecting the presence of beam shielding of the monitoring beam B. A detection sensitivity of the beam shielding detection section 66 is configured to be switched from a normal sensitivity mode to a high sensitivity mode when bending is initial processing based on a predetermined processing program, and an acquired height position of the beam receiver 52 is lower than a predetermined second height position LP2.

First claim

The invention claimed is:

1. An optical safety device for monitoring entry of foreign matter between an upper tool and a lower tool of a press brake, the optical safety device comprising:
a beam projector provided on one side in a length direction of an upper table of the press brake and configured to project a monitoring beam passing through an area and surroundings immediately below the upper tool toward another side in the length direction of the upper table;
a beam receiver provided on the other side in the length direction of the upper table and configured to receive the monitoring beam; and
a monitoring controller comprising:
a received beam amount acquisition section configured to acquire a received beam amount of the beam receiver at certain sampling time intervals; and
a beam shielding detection section configured to detect presence or absence of beam shielding of the monitoring beam by determining whether or not the acquired received beam amount of the beam receiver is lower than a determination threshold for detecting the presence of beam shielding of the monitoring beam,

wherein a detection sensitivity of the beam shielding detection section is configured to be switched from a normal sensitivity mode to a high sensitivity mode when:
a bending process by use of the press brake is an initial process based on a predetermined processing program, and
a height position of the beam receiver is lower than a predetermined height position that is a position immediately above a height position of an upper surface of a workpiece set in the predetermined processing program.

2. The optical safety device according to claim 1 , wherein the monitoring controller further comprises:
a threshold setting section configured to set a normal sensitivity threshold for detecting the presence of beam shielding of the monitoring beam and a high sensitivity threshold for detecting the presence of beam shielding of the monitoring beam, the high sensitivity threshold being higher than the normal sensitivity threshold; and
a threshold selection section configured to select either the set normal sensitivity threshold or the set high sensitivity threshold as the determination threshold,
wherein the threshold selection section selects the high sensitivity threshold as the determination threshold when:
the bending process by use of the press brake is the initial process based on a predetermined processing program, and
a height position of the beam receiver is lower than a predetermined height position that is a position immediately above a height position of an upper surface of a workpiece set in the predetermined processing program.

3. The optical safety device according to claim 1 , wherein
the normal sensitivity mode is a mode in which the presence of beam shielding of the monitoring beam is detected when the received beam amount of the beam receiver is determined continuously for a plurality of times as being lower than the determination threshold, and
the high sensitivity mode is a mode in which the presence of beam shielding of the monitoring beam is detected when the received beam amount of the beam receiver is determined as being lower than the determination threshold, for a fewer times than a number of times of the continuous determination in the normal sensitivity mode.

4. The optical safety device according to claim 1 , wherein the monitoring controller further comprises a workpiece detection section configured to detect presence or absence of a workpiece on the lower tool based on the detection result from the beam shielding detection section in a state in which the detection sensitivity of the beam shielding detection section is switched to the high sensitivity mode.

5. The optical safety device according to claim 4 , wherein the monitoring controller further comprises:
a workpiece height position acquisition section configured to acquire an actual height position of the upper surface of the workpiece based on the height position of the beam receiver at time of detecting the presence of the workpiece on the lower tool; and
a correctness determination section configured to determine whether or not the acquired actual height position of the upper surface of the workpiece is correct as compared with the height position of the upper surface of the workpiece set in the predetermined processing program.

6. The optical safety device according to claim 4 , wherein the detection sensitivity of the beam shielding detection section is configured to be switched from the high sensitivity mode to the normal sensitivity mode when the presence or absence of the workpiece on the lower tool is detected.

7. A press brake comprising
an upper table;
an upper tool;
a lower tool; and
an optical safety device for monitoring entry of foreign matter between the upper tool and the lower tool, the optical safety device comprising:
a beam projector provided on one side in a length direction of the upper table and configured to project a monitoring beam passing through an area and surroundings immediately below the upper tool toward another side in the length direction of the upper table;
a beam receiver provided on the other side in the length direction of the upper table and configured to receive the monitoring beam; and
a monitoring controller comprising:
a received beam amount acquisition section configured to acquire a received beam amount of the beam receiver at certain sampling time intervals; and
a beam shielding detection section configured to detect presence or absence of beam shielding of the monitoring beam by determining whether or not the acquired received beam amount of the beam receiver is lower than a determination threshold for detecting the presence of beam shielding of the monitoring beam,
wherein a detection sensitivity of the beam shielding detection section is configured to be switched from a normal sensitivity mode to a high sensitivity mode when:
a bending process by use of the press brake is an initial process based on a predetermined processing program, and a height position of the beam receiver is lower than a predetermined height position that is a position immediately above a height position of an upper surface of a workpiece set in the predetermined processing program.

8. A workpiece detection method of a press brake system, comprising:
acquiring a received beam amount of a beam receiver at certain sampling time intervals in a state in which a beam projector provided on one side in a length direction of an upper table of a press brake projects a monitoring beam passing through an area and surroundings immediately below an upper tool toward another side in the length direction of the upper table, and the beam receiver provided on the other side in the length direction of the upper table receives the monitoring beam; and
detecting presence or absence of beam shielding of the monitoring beam so as to detect presence or absence of a workpiece, by determining whether or not the acquired received beam amount of the beam receiver is lower than a determination threshold for detecting the presence of beam shielding of the monitoring beam,
wherein a detection sensitivity of the presence or absence of beam shielding of the monitoring beam is switched from a normal sensitivity mode to a high sensitivity mode when:
a bending process by use of the press brake is an initial process based on a predetermined processing program, and
a height position of the beam receiver is lower than a predetermined height position that is a position immediately above a height position of an upper surface of the workpiece set in the predetermined processing program.

Assignees

• Amada Co Ltd

Inventors

• Amano Kanehide
• Sasaki Hideki
• Aoki Takayuki
• Suzuki Taichi
• OHASHI Humitaka

Classifications

• B21D5/0209 Primary

  Tools therefor · CPC title

• B21D55/00

  Safety devices protecting the machine or the operator, specially adapted for apparatus or machines dealt with in this subclass (for presses in general B30B; safety devices in general F16P) · CPC title

• G01V8/12

  using one transmitter and one receiver · CPC title

• B21D5/02 Primary

  on press brakes without making use of clamping means · CPC title

• B30B15/00

  Details of, or accessories for, presses; Auxiliary measures in connection with pressing (safety devices F16P) · CPC title