Patent Publication Number: US-5152541-A

Title: Chuck

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a chuck for chucking predominantly chip-removing tools such as milling cutters, drills, countersinks and the like which have a cylindrical shaft and, in accordance with appropriate standards, at least one drive surface or recess on the shaft. The drive surface or recess defines stop shoulders in axial direction. 
     2. Description of the Related Art 
     Because of the arrangement of the radial chucking elements at a head portion or free end of the chuck, the collect chucks or the so-called sleeve chucks which have been used in the past for these types of tools and which have a clamping screw which acts radially on the tool shaft have a relatively large diameter, so that it is in many cases difficult or even impossible to reach certain locations of workpieces to be worked on. 
     SUMMARY OF THE INVENTION 
     Therefore, it is the object of the present invention to provide a novel chuck for commercially available tools of the types described above, wherein the chuck can have any chosen length at its free end which surrounds the tool shaft and the diameter can be kept extremely small. 
     In accordance with the present invention, a chuck is provided in which the chucking force acting on the tool shaft extends essentially in axial direction and the chucking force is transmitted through a locking member between the tool shaft and the front portion of the chuck. 
     The chuck according to the present invention has the advantage that the front portion of the chuck is free of radially acting chucking elements and, therefore, the chuck can have such a small diameter or wall thickness which provides sufficient material strength for absorbing the work forces acting on the tool. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawing: 
     FIG. 1 is a longitudinal sectional view of a chuck according to the present invention; and 
     FIG. 2 is a longitudinal sectional view of another embodiment of the chuck according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The chuck 3, 3a illustrated in the drawing is used for chucking predominantly chip-removing tools 1, such as milling cutters, drills, countersinks and the like which have a cylindrical shaft la and a drive surface 1b which is arranged recessed on the shaft 1a. The recessed drive surface 1b has stop shoulders 1c or the like in axial direction. 
     Thus, as mentioned above, the chuck according to the present invention provides the advantage over the prior art chucks that the chucking force P acting on the tool shaft 1a extends in axial direction and is transmitted by a locking member 2 or 2a between tool shaft 1a and front portion 3a of the chuck. 
     In a specific embodiment of the present invention, the chuck includes an elongated sleeve 3, 3a with concentrically arranged longitudinal bore 1d, a clamping screw 4 inserted in an end of the sleeve 3, 3a and a duct 3b in the front portion 3a of the chuck which is accessible from the outside and serves for insertion of the locking member 2 or 2a. 
     In accordance with an advantageous feature of the invention, the duct 3b in the front portion 3a of the chuck which receives the locking member 2 or 2a extends from the outer surface of the front portion 3a obliquely toward the free, slightly tapering end 3c of the front portion 3a. The shape of the cross-section of the duct 3b corresponds to the shape of the locking member which may be a spherical member 2, a polygonal member 2a or the like. The configuration as a polygonal member in an also polygonal duct is particularly advantageous for larger tools and greater work pressures. FIG. 2 shows such a member 2a. The polygonal locking member 2a has the additional advantage that the rear side 2a&#39; of the member 2a extends parallel and contacts the stop shoulder 1c of the drive surface 1b. 
     In accordance with another important feature of the invention, the chucking force P is transmitted from the clamping screw 4 through the tool shaft 1a to the locking member 2 or 2a by means of pressure piece 5 in the form of a loosely inserted, cylindrical intermediate member. To make possible a supply of cooling agent, the pressure piece 5, as well as the clamping screw 4, 4b and the tool shaft 1a can be tubular or provided with an internal bore 6. 
     The chuck according to the present invention makes it possible for the first time to construct the front portion 3a of the chuck with a diameter d which is significantly smaller than the diameter D of the chuck sleeve 3 and in which, depending on the type of application, the front portion 3a of the chuck can have any chosen length L without causing vibrations or the like on the tool. This is because the rod-shaped or tubular pressure piece 5 which is clamped into the chuck has a stabilizing effect on the entire chucking sleeve 3. 
     Among other advantages provided by the chuck according to the present invention shown in FIGS. 1 and 2 are the following: 
     a) Because of its slender construction, the chuck of the invention permits the use of normal tools where otherwise extremely long and, thus, expensive special tools would have to be used; 
     b) it is possible to use solid cross-section hard metal tools for working on deep drillings and drillings near edges while obtaining excellent times per piece, which also results in significant savings because expensive special tools are not required; 
     c) the chucking system is suitable for all tools which have a chucking or drive surface or similar surface; and 
     d) the combined chucking arrangement stabilizes the tool and additionally makes possible an internal cooling agent supply. 
     While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.