|Publication number||US20080016998 A1|
|Application number||US 11/865,956|
|Publication date||Jan 24, 2008|
|Filing date||Oct 2, 2007|
|Priority date||Apr 29, 2003|
|Also published as||US7290474, US20060096425|
|Publication number||11865956, 865956, US 2008/0016998 A1, US 2008/016998 A1, US 20080016998 A1, US 20080016998A1, US 2008016998 A1, US 2008016998A1, US-A1-20080016998, US-A1-2008016998, US2008/0016998A1, US2008/016998A1, US20080016998 A1, US20080016998A1, US2008016998 A1, US2008016998A1|
|Original Assignee||Keller David V|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (13), Classifications (21)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present application is a continuation-in-part of U.S. patent application Ser. No. 10/836,132 filed Apr. 29, 2004 (Attorney Docket No. DEL 03-8-2), which in-turn claims priority under 35 USC §119(e) to provisional U.S. Application No. 60/466,199 filed Apr. 29, 2003 (Attorney Docket No. DEL 03-8-1). In addition, the present application claims priority entitled under 35 U.S.C. §119(e) to provisional U.S. Application No. 60/533,192 filed Dec. 30, 2003 (Attorney Docket No. DEL 03-47-1). Said U.S. patent application Ser. No. 10/836,132 and U.S. Provisional Patent Applications Nos. 60/466,199 and 60/533,192 are herein incorporated by reference in their entirety.
The present invention relates generally to the field of saws and more particularly to a detection system and method for rapidly stopping a spinning saw blade.
There exists a need for an effective method to rapidly stop a spinning saw blade in response to input from a sensing device that detects possible contact of the blade with a user's hand. Currently, various methods of stopping a saw blade under such conditions are available. For example, some methods employ a brake which makes contact with the blade and causes the blade to drop below the table surface if the user's hand has made contact with the saw blade. Additional methods utilize a three-in-one system including a splitter, anti-kickback fingers and a blade cover.
All of the presently available systems and methods have one or more disadvantages in terms of convenience of use, early and effective detection of a user's hand and cost. For instance, the system which employs a brake mechanism destroys the saw blade when used. Further, such system requires contact be made between the user and the blade prior to activation of the braking mechanism. Additionally, employment of the three-in-one system severely limits the flexibility of the machine (e.g. user is limited to making through-cuts because the splitter sits higher than the blade, any partial cut such as a groove or a joint may not be done without removing the entire system).
Therefore, it would be desirable to design a system and a method for stopping a rapidly spinning table saw blade overcoming the aforementioned limitations of inflexibility and required user/saw blade contact thereby resulting in an efficient, flexible, early to detect stopping system.
In a first aspect of the invention, a system for stopping a spinning saw blade is disclosed. Such system is comprised of a pin assembly disposed adjacent to a saw blade assembly for stopping a spinning saw blade. A receiving block is disposed on a side of the saw blade assembly opposing the pin assembly for receiving the tip of the pin assembly. A driving assembly is coupled to the pin assembly for driving the pin assembly into the spinning saw blade into the receiving block. Finally, a sensing assembly is coupled to at least one of the saw blade assembly and the driving assembly for sensing encroachment of a user's hand in a pre-defined zone. In use, upon sensing a user's hand the sensing assembly signals the driving assembly to stop the spinning saw blade by driving the pin assembly through the saw blade and into the receiving block. In additional embodiments of the present invention, the sensing assembly includes shape recognition technology. Further, the pin assembly is actuated by an explosive substance wherein the explosive substance is contained within a replaceable cartridge.
In a second aspect of the invention, a method for stopping a rapidly spinning saw blade is disclosed. Such method is comprised of detecting a user's hand in a pre-defined zone by a detecting system and driving a pin assembly through the saw blade into a receiving block to stop the saw blade from spinning upon detecting the presence of a user's hand.
The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which:
Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.
Referring in general to
Referring in general to
The video proximity device may utilize a number of different techniques for detecting the presence of a human body part. In one embodiment, the video from the video proximity device is analyzed by an information handling system (e.g. a computer) having pattern recognition hardware or software for identifying the unique shapes and patterns of human body parts, as differentiated from the shapes and patterns of a workpiece. For example, a human hand is comprised of a series of rounded edges, while a workpiece generally includes linear edges. In another embodiment, an information handling system includes motion analysis hardware or software capable of detecting the movement of a human body part, as differentiated from the movement of a workpiece. For example, a human hand moves in a non-linear, or somewhat erratic, manner, while a workpiece is directed in a line parallel to the orientation of a tool element. In a further embodiment, the video camera comprises a thermal imaging camera, capable of distinguishing the heat signature of a human body part from the heat signature of a workpiece. For example, a human body part is typically of a higher temperature than the temperature of a workpiece in the same environment, and thus is distinguishable by such a system. It should be noted that one of skill in the art may contemplate other video processing and recognition techniques without departing from the scope and intent of the present invention.
The video proximity device may be positioned in a number of different orientations in order to provide a substantially unobstructed view of the working tool element and the adjacent area. In one embodiment, the video proximity device is mounted on an assembly above the support surface. For example, in the case of a table saw, a video camera is mounted on a support assembly above the saw blade, providing a view of the blade and surrounding area. In another embodiment, the video proximity device is mounted to the power tool itself. For example, in the case of a table saw, a video camera is mounted in the fence of the table saw, providing a generally unobstructed view of the blade and surrounding area. Additionally, fiber optic cameras may be desirable in order to minimize intrusion and the like.
The video proximity device may be employed in concert with various systems for alerting the operator of their encroachment into a predefined zone or point. In one embodiment, the support surface of the power tool is clearly marked to indicate the limits of one or more predefined zones. For example, in the case of a table saw, a “red zone” is clearly marked on the support surface, indicating that if an operator's body part encroaches into this zone, the saw blade will be stopped by driving a pin assembly into the side of the saw blade. It should be noted that more than one zone may be defined, and the video proximity device may be capable of distinguishing encroachment into different zones. This may serve not only to provide an additional signal to the operator, but also to minimize the situations in which the pin assembly is actuated. In the case of the table saw, the red zone is surrounded by a caution zone or “yellow zone,” for example. If an operator's hand encroaches into the caution/yellow zone, power to the motor driving the saw blade or the working tool is terminated, or the tool is moved below a support surface, causing no permanent damage to the saw blade. Such a configuration may have the added benefit of providing a gradual slowdown for the working tool element. In the case of a table saw utilizing a yellow zone/red zone combination, for example, initially slowing the saw blade in the yellow zone allows the blade to be stopped more quickly and more effectively in the red zone, reducing potential harm to an operator and to the power tool.
In another embodiment of the sensing assembly, a laser device is used with the video proximity device for clearly marking the boundaries of a zone. In one embodiment, the laser device projects a beam of visible light onto the support surface/workpiece, indicating to an operator the limits of the zone. This configuration provides the added benefit of visually indicating to the operator encroachment into the zone outlined by the beam, which may appear on the encroaching part of the operator's body.
Referring specifically to
Referring specifically to
Referring specifically to
In the alternative to the sensing assembly including a video proximity device, such assembly may recognize the difference in the electrical properties of wood and a user whereby the system projects a high-frequency electrical signal on the saw blade and monitors changes in the signal such as by utilizing one of the assemblies presently known in the art. For example, under normal operating conditions, the signal would remain unaltered for wood includes a relatively small inherent electrical capacitance and conductivity and therefore, the presence of wood in the electrical field would not result in an alteration of such field. However, if a user's hand made contact with the saw blade 102, the detection system 100 would be activated by the sensing assembly detecting a change in the electrical signal as a result of the relatively large inherent capacitance of the user's body. For instance, contact detection electrodes are coupled to the saw blade to detect fluctuations in capacitance.
As illustrated in
In addition to the pin assembly 126, the stopping system includes a driving assembly 128. In an exemplary embodiment, the driving assembly 128 is coupled to the pin assembly 126 for driving the pin assembly 126 into the spinning saw blade 102. Further, the driving assembly 128 includes a communication system which allows the driving assembly 128 to communicate with the sensing assembly. For example, the driving assembly 128 may be hard-wired 130 to the sensing assembly as demonstrated in
Moreover, in an exemplary embodiment of the present invention, an explosive or capable of detonation substance is coupled to a piston which upon actuation causes the pin assembly 126 to be propelled into the spinning saw blade. The explosive actuated pin assembly 126 results in such assembly making an instantaneous forced entry into the saw blade 102 causing the saw blade 102 to stop spinning immediately. As such, in one embodiment, the explosive substance is contained in a replaceable cartridge 132 (e.g. a blank cartridge including a .22 or a .27 caliber load). In additional embodiments, the drive assembly 128 may be electromagnetic, mechanical (e.g. a spring system or mallet activated), or the like. It will be appreciated that activation of the pin assembly 126 by the drive assembly 128 will generally require the replacement of the explosive substance (e.g. the replaceable cartridge, 132). However, use of a replaceable cartridge system will allow a user to easily replace the explosive substance prior to resuming use of the saw.
In a further embodiment of the present invention, a receiving block 134 is disposed on the second side of the saw blade 102 for receiving the tip of the pin assembly 126. In one exemplary embodiment, as illustrated in
In an additional embodiment, the pin assembly 126 may be retracted from the saw blade 102 and the receiving block 134 by blowing compressed air through a port hole 138 located within the drive assembly 128. Such port hole 138 also functions as an exit for the air generated during the release of the explosive substance.
In still a further embodiment, the detection system 100 may include a self-check feature whereby each time the table saw is turned on, the detection system 100 performs a system check to ensure that the system is properly working. If the system is not properly working, the user may be notified by a warning signal including flashing lights or power being cut to the motor. In an additional embodiment, the detection system 100 may include a bypass feature which would allow the system to be turned off if necessary. For example, if the sensing assembly is triggered by detecting a difference in capacity, if a user desires to cut a piece of metal with such saw it would be preferable to turn-off the detection system. The detection system may be set-off unnecessarily whereby the capacitance of a piece of wood is much less than that of a piece of metal and thus, the system may sense a change in capacitance due to the type of material being cut not because of entry of a users hand into a predefined zone. Those of skill in the art will appreciate that while the present drawings illustrate the present invention in use on a table saw, such invention may be adapted to be coupled to variety of power tools including a miter saw, chop saws, radial arm saws, circular saw, and the like without departing from the scope and spirit of the present invention.
In addition to the detection system, a method for stopping a spinning saw blade 200 is disclosed. As illustrated in
It is believed that the present invention and many of its attendant advantages will be understood by the foregoing description, and it will be apparent that various changes may be made without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely an explanatory embodiment thereof, it is the intention of the following claims to encompass and include such changes.
Further, it is understood that the specific order or hierarchy of steps in the methods disclosed are examples of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the method can be rearranged while remaining within the scope of the present invention. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7628101||Oct 30, 2006||Dec 8, 2009||Power Tool Institute||Pyrotechnic drop mechanism for power tools|
|US7640837||Mar 27, 2008||Jan 5, 2010||Sd3, Llc||Table saw with improved safety system|
|US7644645||Nov 17, 2008||Jan 12, 2010||Sd3, Llc||Apparatus and method for detecting dangerous conditions in power equipment|
|US7661343||Apr 17, 2007||Feb 16, 2010||Sd3, Llc||Brake mechanism for power equipment|
|US7895927||May 19, 2010||Mar 1, 2011||Sd3, Llc||Power equipment with detection and reaction systems|
|US8011279||Dec 17, 2007||Sep 6, 2011||Sd3, Llc||Power equipment with systems to mitigate or prevent injury|
|US8074546||Nov 23, 2009||Dec 13, 2011||Power Tool Institute||Pyrotechnic drop mechanism for power tools|
|US8091456 *||Mar 25, 2008||Jan 10, 2012||Power Tool Institute||Safety devices for saws|
|US8479627 *||Nov 29, 2011||Jul 9, 2013||Power Tool Institute||Safety devices for saws|
|US8490527||Sep 1, 2011||Jul 23, 2013||Sd3, Llc||Power equipment with systems to mitigate or prevent injury|
|US8534174||Sep 27, 2010||Sep 17, 2013||Power Tool Institute||Pyrotechnic actuator and power cutting tool with safety reaction system having such pyrotechnic actuator|
|US20120067186 *||Nov 29, 2011||Mar 22, 2012||Power Tool Institute||Safety devices for saws|
|WO2010144627A2 *||Jun 9, 2010||Dec 16, 2010||Butler David J||Health and safety system for a table saw|
|U.S. Classification||83/13, 83/58|
|International Classification||B26D5/00, B23D59/00, B27B5/38|
|Cooperative Classification||Y10T83/081, Y10T83/04, Y10T83/773, Y10T83/8863, F16P3/144, F16P3/148, F16P3/142, Y10S83/01, B23D59/001, B27G19/02, B27B5/38, F16P3/14|
|European Classification||B27G19/02, B23D59/00B, B27B5/38, F16P3/14|