Chucks or sockets – Socket type – Lost motion
Reexamination Certificate
2002-03-07
2003-12-30
Bishop, Steven C. (Department: 3722)
Chucks or sockets
Socket type
Lost motion
C279S074000
Reexamination Certificate
active
06669206
ABSTRACT:
This application claims priority of U.K. Patent Application No. GB 0105547.7, filed Mar. 7, 2001, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tool holder for a rotary hammer or chisel hammer.
2. Description of the Related Art
Different types of tool holder are known which have a main body with, extending rearwards from the front end thereof, a receiving opening for the shank of a drill bit or chisel of the type having at least one axial groove closed at both ends. The main body is formed with at least one axially extending elongate through-opening in the wall of the main body. A locking element of smaller axial length than the through-opening is inserted in the through-opening. The locking element in a locked position is supported against outward radial displacement and, when the drill bit or chisel is inserted, engages in the at least one axial groove thereof. The locking element in a released position is displaceable radially outwards relative to the locked position. A forwardly biased supporting ring is provided on the main body, which is axially movable between a position supporting the locking element in the locked position and a second position defining the released position of the locking element. The tool holder also has an adjusting sleeve, which is axially movable to move the supporting ring between positions.
It should be mentioned that, in addition to the at least one axial groove closed at both ends, the drill bits insertable in such a tool holder generally have at least one further axial groove offset through 90° with respect to the axial groove, which further groove is open at the rear end of the drill bit and in the inserted state of the drill bit is engaged by an axial rib of the main body, by means of which the torque for rotation of the drill bit is transferred to the drill bit. Such drill bits are known, for example, as so-called SDS-Plus and SDS-Max drill bits. Since no rotary forces are transferred to chisels that are used in a chisel hammer, the shank of such a chisel often does not have an axial groove open at the rear end, but only one or two axial grooves closed at both ends, in which the locking element or elements engage to hold the chisel fixedly in the tool holder so that it has limited axial displacement.
In a known tool holder of the above-mentioned kind (EP 0 668 127 A1), there are two diametrically opposite elongate through-openings in the main body, and inserted in each of these through-openings is a locking element in the form of a cylindrical roller. In the locked position the cylindrical roller is located at the front end of the through-opening and is supported by a supporting ring against radial outward displacement. To secure this front position of the locking elements, a divided supporting plate is provided, which engages with finger-like radially inwardly directed extensions into the through-openings and is pressed by a spring into a front position, which is defined by the front or locked position of the supporting ring. By pushing back an adjusting sleeve, the supporting ring is displaced axially rearwards as far as the rear end of the locking elements into its second position. In the region in front of the supporting ring, the adjusting sleeve has an inner wall lying radially further outwards than the inner surface of the adjusting sleeve, so that the locking elements are then able to yield radially outwards into that region of the adjusting sleeve, in order to disengage from the axial grooves in the shank of the inserted drill bit or chisel and release the latter.
If a drill bit or chisel is inserted into this tool holder, then the rear end of its shank comes into contact with the front ends of the locking elements, and these are brought into engagement with the finger-like extensions of the disc projecting into the through-openings of the main body and together with the disc are displaced rearwards against spring force until they are able to yield radially outwards behind the supporting ring located in the locked position, so that the shank can be introduced further into the receiving opening until the locking elements enter its axial grooves and, as a result of the spring force acting on the supporting disc, are again moved forwards into their starting position. In that position, they are then supported by the supporting ring against outward radial displacement.
This tool holder works satisfactorily and combines a compact construction with simple assembly. But because the forces acting on the locking elements and the surrounding parts increase with heavier-duty rotary hammers and chisel hammers, the diameter and/or the length of the cylindrically shaped locking elements has to be correspondingly increased. This leads to an increase in the breadth and/or axial length of the through-openings of the main body, however, and hence to substantial material weakening. Extending the locking element moreover requires a greater axial travel of the supporting ring for displacement into its second position and also a greater axial travel of the locking element for displacement into the position in which it is able to yield radially outwards, and consequently an increase in the overall axial length of the tool holder.
It is furthermore already well known to use, instead of cylindrically shaped locking elements, shaped elements that in the locking position project beyond the periphery of the outer wall of the circumference of the main body, and which cooperate both with a radially stepped supporting ring and with a positioning ring, the positioning ring engaging by means of a finger portion in a radially outwardly open recess in the locking element. The positioning ring is spring-loaded in the forward direction and therefore presses forwards the locking element and the adjusting sleeve that is present, so that the locking element is positioned in a region of the supporting ring which supports the locking element against radially outward displacement. If the adjusting sleeve is displaced axially rearwards by the user, then the positioning ring is also displaced rearwards, and on being displaced the finger portion of the positioning ring takes the locking element with it. The locking element therefore enters a position in relation to the supporting ring in which the locking element can be displaced radially outwards, so that the inserted drill bit or chisel can be withdrawn from the receiving opening of the main body.
When a drill bit or chisel is inserted into this known tool holder, the locking elements are displaced axially rearwards by abutment of the rear end of the drill bit or chisel against the front end of the locking elements, and hence the positioning ring too is pushed rearwards against the force of the forwardly acting spring until the locking elements have reached the above-mentioned position in which they are able to yield radially outwards in the region of the supporting ring. The rear end of the drill bit or chisel then slides past the locking elements, and the spring-loaded positioning ring displaces the locking elements axially forwards into the through-openings of the main body, so that they enter the axial grooves of the shank of the drill bit or chisel and take up the position in which the supporting ring supports them against radially outward displacement.
This known construction allows the use of compact locking elements of greater strength than the roll-shaped locking elements, but, in addition to the use of a supporting ring, requires the use of a positioning ring, by means of which displacement of the locking elements is effected by movement of the adjusting sleeve. Moreover, the external shape of the locking elements is comparatively complicated, so that a complicated mould is required for manufacture, if this involves sintering, for example.
In a further known tool holder design disclosed in GB2,338,672 the tool holder is constructed with locking elements consisting of a shaped element which, on its radially outerm
Bishop Steven C.
Black & Decker Inc.
Del Ponti John D.
Leary Michael P.
Yocum Charles E.
LandOfFree
Tool holder for a rotary hammer or chisel hammer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tool holder for a rotary hammer or chisel hammer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tool holder for a rotary hammer or chisel hammer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3139983