Safety systems for power equipment

• US 9,724,840 B2
• Filed: 03/13/2002
• Issued: 08/08/2017
• Est. Priority Date: 10/01/1999
• Status: Expired due to Term

• Current Assignee: Sawstop Holding LLC
• Original Assignee: SD3, LLC
• Inventors: Gass, Stephen F.
• Primary Examiner(s): Alie, Ghassem
• Application Number:
  US10/100,211
• Publication Number:
  US 20020170399A1
• Time in Patent Office: 5,627 Days
• Field of Search: 83397, 833971, 834712, 834713, 83473, 83477, 834771, 83480, 83DIG 1, 83485, 83589, 83581, 83491, 83 58, 83 671, 83 621, 83781, 83 62, 83490, 83630, 56 104, 56 113, 1441545, 144356, 144384, 144391, 144427, 1442865, 337 1, 337 5, 337 10, 337 17, 337 70, 337140, 337148, 337170, 337190, 337237, 337238, 403 2, 411 2, 411 39, 411390, 74 2, 74814, 102432, 102484, 102377, 102430, 335142, 335 1, 335132, 218 2, 218154, 188 827, 188 82, 188 74, 188 8277, 188 828, 188376, 188377, 307147, 307115, 307116, 307117, 307326, 307126, 307131, 192129 R, 192133, 192148, 192144, 192142 R, 192138, 192137, 192130, 340680, 3406865, 340568, 340590, 361 1, 361124, 361105, 30382, 30381, 169 42, 318362
• 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: 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 13/16 Accessories, e.g. for cooling the 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: B27G 21/00 Safety guards or devices specially designed for other wood-working machines auxiliary devices facilitating proper operation of said wood-working machines
• CPC Class Codes: F16D 2127/008 Trigger mechanisms
• 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 3/144 using light grids
• CPC Class Codes: F16P 3/145 using magnetic technology
• CPC Class Codes: F16P 3/147 using electro-magnetic technology, e.g. tags or radar
• CPC Class Codes: F16P 3/148 using capacitive technology
• CPC Class Codes: G05B 19/4061 Avoiding collision or forbidden zones
• CPC Class Codes: G05B 2219/45044 Cutting
• CPC Class Codes: G05B 2219/49141 Detect near collision and slow, stop, inhibit movement tool
• CPC Class Codes: G05B 2219/49159 Avoid pinching of persons between moving and fixed part
• CPC Class Codes: Y10T 83/089 Responsive to tool characteristic
• CPC Class Codes: Y10T 83/704 With work-support and means to vary relationship between tool and work support

Abstract

Machines with safety systems are disclosed. The machine may take the form of woodworking machines including table saws, band saws, miter saws, hand-held circular saws, pneumatic chop saws, radial-arm saws, jointers, planars, routers and shapers. The machines may include an operative structure configured to perform a task, where the operative structure includes a cutting tool adapted to move in at least one motion, and a safety system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool and for mitigating the unsafe condition. The safety system may include a detection subsystem and a reaction subsystem.

Claims

1. A machine comprising:

an operative structure adapted to perform a task, where the operative structure includes a circular blade having a perimeter and teeth disposed about the perimeter, where the blade is adapted to spin, and where the blade when spinning cuts an object that moves into contact with the teeth;

an electronic detection circuit including an electrical connection to the blade, where the electronic detection circuit is configured to detect when a person is in contact with the teeth when the blade is spinning; and

an electrically triggerable actuator supported by the operative structure and electrically connected to the electronic detection circuit, where the actuator generates a force that causes the blade to stop cutting the person within 10 milliseconds after being triggered if the person moves into contact with the teeth at a rate of one foot per second or less.

2. The machine of claim 1 where the actuator causes the blade to stop cutting the person within 2 to 10 milliseconds after being triggered if the person moves into contact with the teeth at a rate of one foot per second or less.

3. The machine of claim 2 where the operative structure includes a work surface and an arbor block that supports the blade, where the arbor block is pivotable between a raised position with at least a portion of the blade above the work surface and a retracted position where the blade is below the work surface, and where the force causes the arbor block to pivot from the raised position to the retracted position to cause the blade to stop cutting the person.

4. The machine of claim 2 where the actuator has an extending portion and a fixed portion, where the force moves the extending portion relative to the fixed portion, and where movement of the extending portion causes the blade to stop cutting the person.

5. The machine of claim 2 further comprising one or both of an arbor block and a brake pawl, and where the actuator acts on the arbor block or the brake pawl.

6. The machine of claim 2 further comprising an electronic firing circuit connected to the electronic detection circuit and to the actuator to trigger the actuator, where the electronic firing circuit generates a trigger signal to trigger the actuator when the electronic detection circuit detects the contact, and where the machine further comprises a brake mechanism adapted to stop the spinning of the blade within 2 to 10 milliseconds after the actuator is triggered.

7. The machine of claim 2 further comprising an electronic firing circuit connected to the electronic detection circuit and to the actuator to trigger the actuator, where the electronic firing circuit outputs electric current to a component of the actuator to heat the component and thereby trigger the actuator.

8. The machine of claim 1, where the electronic detection circuit includes an oscillator that generates an oscillating signal, where the oscillating signal is imparted on the blade through the electrical connection, where the electronic detection circuit further includes a controller that detects a change in the oscillating signal on the blade indicative of the person being in contact with the teeth when the blade is spinning, and further comprising an electronic firing circuit connected to the electronic detection circuit and to the actuator to trigger the actuator, where the electronic firing circuit generates a trigger signal when the controller detects the change in the oscillating signal on the blade, and where the trigger signal triggers the actuator.

9. A machine comprising:

an operative structure adapted to perform a task, where the operative structure includes a circular blade having a perimeter and teeth disposed about the perimeter, where the blade is adapted to spin; and

a safety system adapted to detect the occurrence of contact between a person and the blade when the blade is spinning, where the safety system includes an electronic circuit adapted to detect the contact, and a reaction subsystem electrically connected to the electronic circuit and adapted to mitigate injury from the contact;

where the reaction subsystem includes an electrically triggerable actuator supported by the operative structure and connected to the electronic circuit, where the electronic circuit triggers the actuator upon detection of the contact, and where the actuator generates a force that causes the blade to stop cutting the person within 10 milliseconds after being triggered if the person moves into contact with the teeth at a rate of one foot per second or less; and

where the reaction subsystem includes a brake mechanism adapted to stop the spinning of the blade within 10 milliseconds after the actuator is triggered.

10. The machine of claim 9 where the blade has a diameter between 9.5 and 10.5 inches.

11. The machine of claim 9 where the blade is a dado cutter.

12. The machine of claim 9 where the machine is a table saw, and where the operative structure includes a table with an opening through which at least part of the blade can extend.

13. The machine of claim 9 where the machine is a hand-held circular saw, and where the operative structure includes a motor configured to drive the blade.

14. The machine of claim 9 where the machine is a miter saw, where the operative structure includes a base defining a cutting zone, a pivot arm attached to the base to pivot toward and away from the cutting zone, and a motor to drive the blade, and where the blade is supported by the pivot arm.

15. The machine of claim 9 where the machine is a radial arm saw, and where the operative structure includes a base, a guide arm, and a carriage slidably coupled to the guide arm.

16. The machine of claim 9 where the brake mechanism is adapted to stop the spinning of the blade within 7 milliseconds after the actuator is triggered.

17. The machine of claim 9 where the brake mechanism is adapted to stop the spinning of the blade within 5 milliseconds after the actuator is triggered.

18. The machine of claim 9 where the brake mechanism is adapted to stop the spinning of the blade within less than 5 milliseconds after the actuator is triggered.

19. The machine of claim 9 where the actuator causes the blade to stop cutting the person within 2 to 10 milliseconds after being triggered if the person moves into contact with the teeth at a rate of one foot per second or less, and where the brake mechanism is adapted to stop the spinning of the blade within 2 to 10 milliseconds after the actuator is triggered.

20. The machine of claim 19 where the electronic circuit includes an oscillator that generates an oscillating signal, where the electronic circuit also includes an electrical connection between the oscillator and the blade, where the oscillating signal is imparted on the blade through the electrical connection, where the electronic circuit further includes a controller that detects a change in the oscillating signal on the blade indicative of the person being in contact with the blade when the blade is spinning, where the electronic circuit generates a trigger signal when the controller detects the change in the oscillating signal on the blade, and where the trigger signal triggers the actuator.

21. The machine of claim 20, where the electrical connection between the oscillator and the blade comprises a capacitive coupling.

22. The machine of claim 21, where the capacitive coupling comprises a plate adjacent the blade.

23. The machine of claim 19 where the brake mechanism includes a pawl adapted to contact the blade.

24. A machine comprising:

an operative structure adapted to perform a task, where the operative structure includes a circular blade having a perimeter and teeth disposed about the perimeter, where the blade is adapted to spin, and where the blade when spinning cuts an object that moves into contact with the teeth;

a detection circuit to detect when a person is in contact with the teeth when the blade is spinning, where the detection circuit includes an oscillator that generates an oscillating signal, where the detection circuit also includes an electrical connection between the oscillator and the blade, where the oscillating signal is imparted on the blade through the electrical connection, where the detection circuit further includes a controller that detects a change in the oscillating signal on the blade indicative of the person being in contact with the teeth when the blade is spinning, and where the detection circuit generates a detection signal when the controller detects the change in the oscillating signal on the blade;

a firing circuit connected to the detection circuit to receive the detection signal, where the firing circuit outputs electric current upon receiving the detection signal; and

a reaction system to stop the blade from cutting the person within 10 milliseconds if the person moves into contact with the teeth at a rate of one foot per second, where the 10 milliseconds is measured from the generation of the detection signal, where the reaction system includes an actuator with a spring or an explosive, where the actuator is connected to the firing circuit to receive the electric current output by the firing circuit, where the electric current received by the actuator from the firing circuit heats a component in the actuator to trigger the spring or explosive to generate a force, and where the reaction system further includes at least one of;

i. a brake to stop the blade, where the force from the spring or explosive causes the brake to stop the spinning of the blade within 10 milliseconds after the spring or explosive is triggered, and

ii. an arbor block supporting the blade, where the force from the spring or explosive causes the arbor block to move and retract the blade at least some amount away from the contact with the person.

25. The machine of claim 24 where the reaction system is adapted to stop the blade from cutting the person within 2 to 10 milliseconds if the person moves into contact with the teeth at a rate of one foot per second, and where the 2 to 10 milliseconds are measured from the generation of the detection signal.

26. The machine of claim 24 where the brake is adapted to stop the spinning of the blade within 2 to 10 milliseconds after the spring or explosive is triggered.

27. The machine of claim 25 where the electrical connection between the oscillator and the blade comprises a capacitive coupling.

28. The machine of claim 25, where the capacitive coupling comprises a plate adjacent the cutting tool.

29. The machine of claim 25, where the firing circuit includes a capacitor.