Actuators for use in fast-acting safety systems

• US 20030020336A1
• Filed: 07/25/2002
• Published: 01/30/2003
• Est. Priority Date: 07/25/2001
• Status: Active Grant

• Current Assignee: Sawstop Holding LLC
• Original Assignee: SD3, LLC
• Inventors: Fanning, David A., Gass, Stephen F.
• Granted Patent: US 6,945,149 B2
• Time in Patent Office: Days
• US Class Current: 307/326
• 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: B23Q 11/0092 actuating braking or stopping means
• CPC Class Codes: B23Q 11/06 Safety devices for circular cutters
• 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: 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 3/148 using capacitive technology
• CPC Class Codes: Y10S 83/01 Safety devices
• CPC Class Codes: Y10T 83/089 Responsive to tool characteristic
• CPC Class Codes: Y10T 83/7697 Tool angularly adjustable relative to work-support
• 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 83/778 And means to rotate tool
• CPC Class Codes: Y10T 83/7788 Tool carrier oscillated or rotated
• CPC Class Codes: Y10T 83/8773 Bevel or miter cut

Abstract

Cutting machines with high-speed safety systems, and actuators used in high-speed safety systems, are disclosed. The cutting machines may include a detection system adapted to detect a dangerous condition between a cutting tool and a person. A reaction system performs a specified action, such as stopping the cutting tool, upon detection of the dangerous condition. An actuator may be used to trigger the reaction system to perform the specified action.

Claims

1. An actuator for use in a safety system for a power tool, where the power tool includes a moving blade, the actuator comprising:

an engagement member adapted to move into contact with the moving blade,

a brake pawl attached to the engagement member so that when the engagement member contacts the moving blade, the blade and engagement member pull the brake pawl into the blade, and

a mechanism adapted to cause the engagement member to move into contact with the blade.

2. The actuator of claim 1, where the mechanism adapted to cause the engagement member to move into contact with the moving blade includes a solenoid.

3. The actuator of claim 1, where the mechanism adapted to cause the engagement member to move into contact with the moving blade includes a shape memory alloy.

4. The actuator of claim 1, where the mechanism adapted to cause the engagement member to move into contact with the moving blade includes a voice coil.

5. The actuator of claim 1, where the mechanism adapted to cause the engagement member to move into contact with the moving blade includes an integrated force array.

6. The actuator of claim 1, where the engagement member is pivotally attached to the brake pawl.

7. The actuator of claim 1, further comprising a restraint mechanism to hold the brake pawl away from the blade during normal use of the power tool.

8. The actuator of claim 1, where the engagement member comprises a U-shaped member.

9. The actuator of claim 1, where the engagement member comprises a wire.

10. The actuator of claim 1, where the engagement member comprises a mesh.

11. The actuator of claim 1, where the engagement member comprises a leaf spring.

12. The actuator of claim 1, where the engagement member and brake pawl are configured so that the force of the moving blade causes the brake pawl to engage the blade.

13. The actuator of claim 1, where the engagement member is configured to pivot into the blade.

14. The actuator of claim 13, further comprising a source of stored force adapted to bias the engagement member toward the blade.

15. The actuator of claim 14, where the mechanism adapted to cause the engagement member to move into contact with the blade includes a solenoid and plunger positioned to prevent the source of stored force from causing the engagement member to pivot into the blade until the plunger is moved by the solenoid.

16. An actuator for use in a safety system for a power tool, where the power tool includes a moving blade, the actuator comprising:

a brake pawl positioned to move into contact with the blade to stop the blade,

a source of stored energy adapted to bias the brake pawl toward the blade,

a plunger barring the brake pawl from moving into contact with the blade, and

a solenoid adapted to retract the plunger to release the brake pawl to move into contact with the blade.

17. The actuator of claim 16, where the source of stored energy is a spring.

18. The actuator of claim 16, where the brake pawl includes a shoulder that abuts the plunger until the plunger is retracted.

19. The actuator of claim 16, further comprising a bearing to support the plunger.

20. An actuator for use in a safety system for a power tool, where the power tool includes a moving blade, the actuator comprising:

engagement means for contacting the blade,

a brake pawl attached to the engagement means so that when the engagement means contacts the blade, the blade and engagement means pull the brake pawl into the blade, and

means for causing the engagement member to move into contact with the blade.