Chucks or sockets – Socket type – Spring biased jaws
Reexamination Certificate
2000-08-30
2003-02-18
Bishop, Steven C. (Department: 3722)
Chucks or sockets
Socket type
Spring biased jaws
C279S051000, C279S054000, C279S156000
Reexamination Certificate
active
06520508
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to drill or router chucks and, more particularly, to keyless router chucks.
Driving devices, such as drills or routers, include a tool retainer which non-rotatably secures a cutting tool, such as a drill bit or a router tool, to the driving device. Rotation of a drive shaft of the driving device then causes a corresponding rotation of the cutting tool. The clamping force of the retainer must provide sufficient gripping action of the tool. Otherwise, if the gripping friction force is overcome, the tool will slip in its holder, which may result in poor performance and hazard to those nearby.
Tool holding systems for woodworking, metalworking, and/or the like have been developed over many years. The most common types of tool holders that offer reasonable flexibility of gripping range are either collet systems or chucks. Common applications for portable electric drills incorporate keyless or keyed drill chucks. Within the metalworking trades such chucks are used for drills, while it is more common to see split steel collets for other applications such as milling or drilling where automated machinery is involved. These types of collets are in broad use today. However, such collets require a substantial amount of torque to be exerted on a threaded retainer in order to attain sufficient clamping force on the tool. This preloads the system such that the frictional engagement between the collet and the cutting tool limits rotational movement therebetween. In order to attain the high torque necessary to achieve the necessary clamping force, typically the user or operator uses wrenches or keys to rotate the threaded retainer, while holding the base or drive tool in a fixed position. Not only is this process cumbersome and sometimes difficult, this also results in the effective clamping forces being dependent on the torque applied by the individual operator, which will vary from one person to another.
In some applications, blade type flexible collet chucks are utilized, which have radial blades that are forced into contact with the cutting tool by the use of tapered cones and tightening nuts. Such collets are in use for light torque applications such as for tap holders and light machining, and are characterized by having substantially greater gripping ranges than the split steel types of collets. In most applications (except for keyless drill chucks), a tightening wrench or wrenches is necessary to cause the collet to grip the tool with sufficient force so that the friction between tool and collet is sufficient to resist the forces of the application.
Collet closers have been proposed which provide for the sufficient clamping force by means other than using tightening wrenches. The collet may be clamped via hand tightening of a threaded retainer on the driving device. However, these collet closers have a very narrow grip range and a wide force requirement to successfully grip over this range. Accordingly, these may be ineffective for tools having a diameter outside of the tight tolerance gripping range of the closers. Furthermore, these closers still require a high manual force to cause the collet to clamp onto the tool, which makes them difficult to use by an operator.
Existing collet systems of the split steel type and of the radial blade type typically match the outside shape of the collet system to that of the cone within which it is tightened. This approach is consistent with the desire to maintain wear resistance on the surfaces that grip the collet by providing large contact surfaces. In the case of the blade type collet chucks, the result of this design practice is to cause the blades to undergo a skewing tendency when the blade is in contact with the tool. This skewing action tends to negate the gripping force system of these designs because it forces the geometry into a violation of the design ratios necessary for the force system to work.
Therefore, there is a need in the art for a keyless chuck which may receive and non-rotatably retain a cutting tool, such as a router bit or the like, therewithin, with minimal force required by an operator of the driving device.
SUMMARY OF THE INVENTION
The present invention is intended to provide a keyless tool receiver or chuck, which is adaptable for use with a powered driving device or driver, such as a router or the like. The tool receiver is biased in an engaged position by a biasing member, whereby an operator may insert a cutting tool or bit within the receiver or release the tool therefrom by overcoming the biasing force of the biasing member. The tool receiver includes a plurality of blades which are biased in the engaged position whereby the blades contact a conical surface of the driver along one side and the cutting tool along the other side. The blades preferably have specific design ratios to further enhance the gripping of the tool by the tool receiver.
According to an aspect of the present invention, the tool receiver is adapted to non-rotatably secure a tool at a driving device. The tool receiver is positioned within a tapered or conical surface of the driving device. The conical surface has a narrow end and a wide end opposite the narrow end. The tool receiver comprises a plurality of blades and a biasing member. The blades are positionable in a generally circular manner at the conical surface and define a generally circular opening. The biasing member is adapted to bias the blades toward the narrow end of the conical surface such that the blades are biased in the retaining position by the biasing member. The blades are adapted to non-rotatably secure a tool with respect to the blades and the conical surface. Preferably, the tool receiver further includes a retaining member which retains the blades and preferably biases the blades radially outward toward the conical surface.
In one form, each of the blades has a thickness and a radial length. A ratio of the thickness to the radial length of each blade is preferably no greater than a coefficient of friction between each of the blades and the cutting tool. Preferably, a ratio of an effective contact width of the blades to the radial length of the blades is less than the coefficient of friction between each of the blades and the cutting tool. Each of the plurality of blades has a tool engaging surface and a cone engaging surface opposite the tool engaging surface. The tool engaging surfaces are adapted to engage a shaft of the tool, while the cone engaging surfaces are adapted to engage the conical surface of the driving device. Preferably, the tool engaging surface of each blade has a thickness which is greater than a thickness of the cone engaging surface of the blade. Preferably, the tool receiver further includes a positive stop member which is adapted to limit insertion of the tool within the circular opening defined by the blades.
According to another aspect of the present invention, a tool receiver for non-rotatably securing a tool to a driving device comprises a plurality of blades, a conical member and a biasing member. Each of the blades has a tool engaging surface and a cone engaging surface opposite the tool engaging surface. The conical member at least partially encases the blades and biases the blades radially inward toward a circular opening defined by the tool engaging surfaces of the blades. The conical member defines a tapered or conical surface which has a narrow end and a wide end opposite the narrow end. The conical member is rotatably drivable by the driving device. The blades are positionable in a generally circular manner within the conical member whereby the tool engaging surfaces of blades define a generally circular opening. The cone engaging surfaces engage the conical surface of the conical member. The biasing member biases the blades toward the narrow end of the conical surface such that the blades are biased in a retaining position by the biasing member and the conical member. The tool receiver is adapted to non-rotatably secure the tool with respect to the blades and the conica
Bishop Steven C.
Jordan Manufacturing Solutions, Inc.
Van Dyke Gardner, Linn & Burkhart, LLP
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