Safety systems for power equipment

• US 10,071,499 B2
• Filed: 08/07/2017
• Issued: 09/11/2018
• Est. Priority Date: 03/13/2001
• Status: Expired due to Fees

• Current Assignee: Sawstop Holding LLC
• Original Assignee: Sawstop Holding LLC
• Inventors: Gass, Stephen F.
• Primary Examiner(s): Alie, Ghassem
• Application Number:
  US15/670,374
• Publication Number:
  US 20170334087A1
• Time in Patent Office: 400 Days
• Field of Search: 834771, 833971, 83DIG 1, 83581, 83666, 83 621, 83 72, 834713, 83 62, 83473, 83488, 83490, 83 58, 83 767, 83481, 834712, 83478, 83487, 83489, 83574, 83821, 83823, 83828, 83954, 83665, 83522, 83 11, 83 22, 83544, 83476, 83491, 83526, 83 768, 83546
• 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 2121/16 for releasing a normally applied brake
• CPC Class Codes: F16D 2127/008 Trigger mechanisms
• CPC Class Codes: F16D 63/006 Positive locking brakes
• 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 19/406 characterised by monitoring or safety G05B19/19 takes precedence
• 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. The machine may also include a bypass or override mode where in an injury mitigation system is disabled for certain cuts.

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;

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;

an electrically triggerable actuator connected to the firing circuit to receive the electric current output by the firing circuit, where the actuator generates a force that causes the blade to stop cutting the object; and

an override, selectively engageable by a user, where the override, when engaged, prevents the firing circuit from outputting the electric current.

2. The machine of claim 1, further including a visual indicator viewable by a user to inform the user the override is engaged.

3. The machine of claim 1, where the operative structure includes a motor to spin the blade;

and where the user can engage the override only as part of a process of starting the motor.

4. The machine of claim 1, where the operative structure includes a motor to spin the blade;

where the motor can be on or off; and

where the override, if engaged while the motor is on, will be disengaged automatically when the motor is off.

5. The machine of claim 1, where the operative structure includes a motor to spin the blade, where the motor can be turned on by a user performing a first action, and where engagement of the override requires a user to perform a second action in addition to and different from the first action.

6. The machine of claim 1, further comprising a motor to spin the blade, a motor on/off switch, and an override switch, and where the override is engaged by switching the override switch and subsequently switching the motor on/off switch.

7. 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 selectively operable motor to spin the blade;

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;

an electrically triggerable actuator connected to the firing circuit to receive the electric current output by the firing circuit, where the actuator generates a force that causes the blade to stop cutting the object; and

where the machine includes a normal mode of operation where the detection circuit generates the detection signal when the controller detects the change in the oscillating signal on the blade when the blade is spinning, and a selectively engageable override mode where the detection circuit does not generate the detection signal when the controller detects the change in the oscillating signal on the blade when the blade is spinning.

8. The machine of claim 7, further including a visual indicator viewable by a user to inform the user the override mode is engaged.

9. The machine of claim 7, where the override mode can be engaged only as part of a process of starting the motor.

10. The machine of claim 7, where the override mode, if engaged while the motor is on, will be disengaged automatically when the motor is off.

11. The machine of claim 7, where the motor can be turned on by a user performing a first action, and where engagement of the override mode requires a user to perform a second action in addition to and different from the first action.

12. The machine of claim 7, further comprising a motor on/off switch and an override switch;

where the override mode is engaged by switching the override switch and subsequently switching the motor on/off switch.