Band saw with improved safety system

• US 20020170400A1
• Filed: 05/15/2002
• Published: 11/21/2002
• Est. Priority Date: 05/17/2001
• Status: Active Grant

• Current Assignee: Sawstop Holding LLC
• Original Assignee: Sawstop Holding LLC
• Inventors: Gass, Stephen F.
• Granted Patent: US 9,927,796 B2
• Time in Patent Office: Days
• US Class Current: 83/62.1
• CPC Class Codes: B23D 55/00 Sawing machines or sawing devices working with strap saw blades, characterised only by constructional features of particular parts constructional features of these parts per se B23Q
• 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: 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 19/06 for band or strap 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: 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: G05B 19/4061 Avoiding collision or forbidden zones
• CPC Class Codes: G05B 2219/45044 Cutting
• CPC Class Codes: G05B 2219/49152 Feedhold, stop motion if machine door is open, if operator in forbidden zone
• CPC Class Codes: G05B 2219/49159 Avoid pinching of persons between moving and fixed part
• 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 83/707 By endless band or chain knife
• CPC Class Codes: Y10T 83/7083 With cutter other than endlessly orbiting type

Abstract

A band saw including a frame, at least two, spaced apart, rotatable wheels supported by the frame, a blade looped around the wheels, where rotation of at least one wheel causes the blade to move around the wheels, a detection system adapted to detect a dangerous condition between a person and the blade, and a reaction system configured to engage and stop the blade within 10 milliseconds after detection of the dangerous condition is disclosed. The reaction system may be configured to cut and grip the blade.

Claims

1. A band saw comprising:

a frame;

at least two, spaced apart, rotatable wheels supported by the frame;

a blade looped around the wheels, where rotation of at least one wheel causes the blade to move around the wheels;

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

a reaction system configured to engage and stop the blade within 10 milliseconds after detection of the dangerous condition.

2. The band saw of claim 1, where the detection system uses capacitance to detect the dangerous condition, and where the dangerous condition is contact between a person and the blade.

3. The band saw of claim 2, where the detection signal imparts an electric charge on the blade through a capacitive coupling.

4. The band saw of claim 3, where the wheels are mounted on shafts, and where the capacitive coupling includes a conductive plate adjacent one of the shafts.

5. The band saw of claim 3, where the wheels are electrically isolated from the rest of the saw.

6. The band saw of claim 3, where the blade is electrically isolated from the rest of the saw.

7. The band saw of claim 6, where the capacitive coupling includes a conductive plate positioned adjacent the blade.

8. The band saw of claim 3, further comprising a housing at least substantially enclosing the wheels, and where the housing is constructed to minimize any capacitive coupling between the housing and the wheels and/or blade.

9. The band saw of claim 8, where the housing is made at least partially of a non-conductive material.

10. The band saw of claim 1, where the reaction system is configured to cut the blade upon detection of the dangerous condition.

11. The band saw of claim 10, where the reaction system is further configured to grip the blade upon detection of the dangerous condition.

12. The band saw of claim 1, where the reaction system includes a cutting element.

13. The band saw of claim 12, where the cutting element is configured to pivot against the blade.

14. The band saw of claim 13, where the cutting element is configured so that when it pivots against the blade, the normal motion of the blade tends to move the cutting further against the blade.

15. The band saw of claim 12, where the cutting element is configured to both cut and grip the blade.

16. The band saw of claim 12, further comprising a spring to bias the cutting element toward the blade.

17. The band saw of claim 16, further comprising a fuse wire to prevent the spring from moving the cutting element toward the blade, where the detection system is configured to fuse the fuse wire upon detection of the dangerous condition, and where the fuse wire prevents the spring from moving the cutting element toward the blade until the detection system fuses the fuse wire.

18. The band saw of claim 12, where the cutting element includes a cutting edge made of carbide or hardened steel.

19. A band saw comprising:

a frame;

at least two, spaced apart, rotatable wheels supported by the frame;

a blade looped around the wheels, where rotation of at least one wheel causes the blade to move around the wheels;

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

reaction means for engaging and stopping the blade within 10 milliseconds after detection of the dangerous condition.

20. A method of operating a band saw, where the band saw includes a conductive blade, a detection system adapted to detect a dangerous condition between a person and the blade, and a reaction system configured to engage and stop the blade within 10 milliseconds after detection of the dangerous condition, the method comprising:

imparting a signal to the blade;

monitoring the signal on the blade by the detection system, where the dangerous condition is represented by a predetermined change in the signal on the blade;

triggering the reaction system upon detection of the predetermined change in the signal on the blade.