Logic control for fast-acting safety system

• US 20100089212A1
• Filed: 10/09/2009
• Published: 04/15/2010
• Est. Priority Date: 08/14/2000
• Status: Active Grant

• Current Assignee: Sawstop Holding LLC
• Original Assignee: SD3, LLC
• Inventors: Jensen, Joel F., Gass, Stephen F., Fulmer, J. David, Schramm, Benjamin B., Chamberlain, Robert L.
• Granted Patent: US 7,921,754 B2
• Time in Patent Office: Days
• US Class Current: 83/62.100
• CPC Class Codes: B23D 59/001 Measuring or control devices, e.g. for automatic control of work feed pressure on band saw blade measuring in general G01; controlling in general G05
• CPC Class Codes: B26D 7/24 arranged to disable the operating means for the cutting member
• CPC Class Codes: B27B 13/14 Braking devices specially designed for band sawing machines, e.g. acting after damage of the band saw blade
• CPC Class Codes: B27B 5/38 Devices for braking the circular saw blade or the saw spindle; Devices for damping vibrations of the circular saw blade, e.g. silencing vibration-damping of sawing machines or devices working with circular saw blades B23D47/005
• CPC Class Codes: B27G 19/00 Safety guards or devices specially adapted for wood saws; Auxiliary devices facilitating proper operation of wood saws
• CPC Class Codes: B27G 19/02 for circular saws
• CPC Class Codes: F16P 3/12 with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine F16P3/08 takes precedence
• CPC Class Codes: F16P 3/14 the means being photocells or other devices sensitive without mechanical contact
• CPC Class Codes: F16P 3/148 using capacitive technology
• CPC Class Codes: Y10S 83/01 Safety devices
• CPC Class Codes: Y10T 83/04 Processes
• CPC Class Codes: Y10T 83/081 With randomly actuated stopping means
• CPC Class Codes: Y10T 83/089 Responsive to tool characteristic
• CPC Class Codes: Y10T 83/148 Including means to correct the sensed operation
• CPC Class Codes: Y10T 83/707 By endless band or chain knife
• CPC Class Codes: Y10T 83/7726 By movement of the tool
• CPC Class Codes: Y10T 83/773 Work-support includes passageway for tool [e.g., slotted table]
• CPC Class Codes: Y10T 83/7788 Tool carrier oscillated or rotated

Abstract

Woodworking machines including cutting tools and motors adapted to drive the cutting tools are disclosed. The machines also include a detection system adapted to detect a dangerous condition between the cutting tool and a person, and a reaction system adapted to perform a specified action upon detection of the dangerous condition. The machines further include a control system adapted to test the operability of at least a portion of the detection system and/or the reaction system. The control system is adapted to disable the motor if the tested portion is inoperable.

Claims

1. A woodworking machine comprising:

a cutting tool for cutting workpieces;

at least one motor configured to drive the cutting tool;

a detection system configured to detect a dangerous condition associated with the cutting tool;

a brake mechanism having at least one replaceable single-use component, and controllable to stop the cutting tool if the dangerous condition is detected; and

a control system configured to detect whether the single-use component has been used, and to disable the at least one motor until the single-use component has been replaced.

2. The machine of claim 1, where the at least one replaceable single-use component includes a fusible member.

3. The machine of claim 2, where the control system is configured to detect whether the fusible member has been melted.

4. The machine of claim 2, where the control system is configured to test the electrical continuity of the fusible member.

5. The machine of claim 2, where the brake mechanism includes a capacitor adapted to store electrical charge, and where the control system is configured to determine the capacitance of the capacitor.

6. The machine of claim 5, where the control system is configured to measure the capacitance of the capacitor through the fusible member.

7. The machine of claim 2, where the brake mechanism includes a capacitor adapted to store electrical charge, and where the control system is configured to determine the electrical charge stored on the capacitor.

8. The machine of claim 7, where the control system is configured to measure the electrical charge stored on the capacitor through the fusible member.

9. A method of controlling a saw, where the saw includes a blade driven by a motor, a detection system adapted to detect a dangerous condition between a person and the blade, and a reaction system associated with the detection system to cause a predetermined action to take place upon detection of the dangerous condition, the method comprising:

checking to see whether the detection system is functioning;

checking to see whether the reaction system is functioning; and

powering the motor to drive the blade if the detection and reaction systems are functioning.

10. The method of claim 9, further comprising checking to see whether the detection system is functioning while the motor is running, and shutting the motor off if the detection system is not functioning while the motor is running.

11. The method of claim 9, further comprising checking to see whether the reaction system is functioning while the motor is running, and shutting the motor off if the reaction system is not functioning while the motor is running.

12. A woodworking machine comprising:

a cutting tool for cutting workpieces;

at least one motor configured to drive the cutting tool;

a detection system configured to detect a dangerous condition between a person and the cutting tool;

a reaction system controllable to disable the cutting tool if the dangerous condition is detected; and

a control system configured to determine the operability of the detection system and to disable the motor if the detection system is inoperable.

13. The machine of claim 12, where the detection system imparts an electrical signal to the cutting tool and monitors the electrical signal for changes indicative of the dangerous condition.

14. The machine of claim 12, where the control system is adapted to determine the operability of the detection system without having to operate the reaction system.

15. The machine of claim 12, where the motor is controllable by the control system, where the control system is configured to determine the operability of the detection system prior to actuation of the motor, and where the control system is further configured not to actuate the motor unless the detection system is operational.

16. The machine of claim 12, where the detection system includes at least one charge plate, where the motor is controllable by the control system, where the control system is configured to detect a predetermined signal on the charge plate prior to actuation of the motor, and where the control system is further configured not to actuate the motor unless the predetermined signal is detected.

17. A woodworking machine comprising:

a support structure;

a cutting tool adapted to move to cut a workpiece, where the cutting tool is supported by the support structure;

a motor adapted to drive the cutting tool;

a detection system adapted to detect a dangerous condition between the cutting tool and a person;

a reaction system adapted to perform a specified action upon detection of the dangerous condition; and

a self-test system adapted to test the operability of at least a portion of the detection system and to disable the motor if the tested portion of the detection system is inoperable.

18. The machine of claim 17, where the detection system imparts an electrical signal to the cutting tool and monitors the electrical signal for changes indicative of the dangerous condition.

19. The machine of claim 17, where the self-test system is configured to determine the operability of the detection system prior to actuation of the motor, and where the motor is not actuated unless the detection system is operational.

20. The machine of claim 17, where the detection system includes at least one charge plate, where the self-test system is configured to detect a predetermined signal on the charge plate, and where the motor is not actuated unless the predetermined signal is detected.