Joints and connections – Member ends joined by inserted section – Expansible section
Reexamination Certificate
2000-07-21
2003-06-17
Browne, Lynne H. (Department: 3679)
Joints and connections
Member ends joined by inserted section
Expansible section
C403S257000
Reexamination Certificate
active
06579027
ABSTRACT:
The invention relates to a device for connecting a tool head, which has a tool shank, to a clamping shank, which has a seat for the tool shank and is preferably arranged at the end side on a machine spindle, with the aid of a clamping mechanism which has at least two clamping elements, which are arranged at an angular distance from one another and, in their clamping position, connect the tool shank and the clamping shank to one another in a force-fitting manner, and an actuating mechanism for the limited displacement of the clamping elements between a release position and a clamping position.
The clamping elements which can be adjusted using the actuating mechanism are used to generate a pressure between planar surfaces of the parts which are to be coupled to one another. In a known device of this type, the claw-like or clip-like clamping elements, at one end, are fitted into the seat of the clamping shank, while at the other end they extend into the interior of the tool shank, which is of hollow design. They can be supported, by means of in each case two clamping shoulders, which are arranged at an axial distance from one another and face toward one another, on clamping surfaces which are arranged in the interior of the clamping shank and of the hollow tool shank and face away from one another, and can be adjusted between a release position and a clamping position by means of the actuating mechanism. One frequently encountered drawback of the known device is that during the clamping operation it is necessary to overcome relatively high frictional forces and spring forces which act in the opposite direction to that of achieving a high clamping force between the parts which are to be coupled. A further drawback of the known coupling device of this type consists in the relatively complicated mechanical structure, which frequently comprises filigree individual parts, of the clamping mechanism, which particularly with small sizes leads to strength and assembly problems.
In view of the above, the invention is based on the object of developing a connecting device of the type mentioned in the introduction which is easy to produce and assemble.
The combinations of features given in patent claims 1, 33, 38, 44, 60, 75 and 82 are proposed in order to achieve this object. Advantageous configurations and refinements of the invention will emerge from the dependent claims.
To achieve this object, according to the invention, it is primarily proposed that in each case one piston-like centering element engage over the clamping insert at its end-side ends, and that the centering elements be rigidly connected to one another by means of axially parallel webs, so as to form a centering cage which engages over the clamping mechanism with axial play, and in each case engage in one axially central, preferably cylindrical recess in the region of the base of the clamping shank and the tool shank, which is preferably designed as a hollow shank, leaving clear an axial space.
The centering cage is expediently designed as an ejector element which, under the action of the actuating mechanism when the clamping mechanism is being released, separates the tool shank from the clamping shank in the axial direction. In a preferred configuration of the invention, a fluid pressure can be applied to the centering cage at its centering element on the clamping shank side, via the free space, in the direction of the hollow shank. The webs may be of hollow design, so as to form in each case one coolant pipe, while the piston-like centering elements have inlet openings and outlet openings which are in communication with the coolant pipes. The clamping mechanism with the actuating mechanism, on the one hand, and the centering cage, which is designed as a coolant bridge, on the other hand, in the assembled state form a structural unit which during assembly can be fitted into the clamping shank by one simple action, and can be locked therein, for example by means of the locking bolt.
Advantageously, the centering element on the clamping shank side has at least one inlet opening which is oriented in an axially parallel direction and can be sealed by means of a radial seal inside the associated recess. To avoid baffle surfaces in the feed line, which could cause the coolant fluid to become segregated, it is advantageous if at least one inlet opening is connected to a central passage on the clamping shank side via an inclined, edgeless inlet passage. Such an arrangement is advantageous in particular for minimal-quantity lubrication, in which a carrier gas laden with oil particles (an aerosol) is used as the coolant fluid instead of a liquid coolant.
The centering element on the hollow shank side advantageously has a central outlet opening which is preferably in communication with the coolant pipes via inclined, edgeless outlet passages, and can be sealed inside the associated recess by a seal which surrounds the outlet opening on the outside. To prevent depositions and pressure drops in the flowing cooling fluid when minimal-quantity lubrication is used, it is proposed, according to a preferred configuration of the invention, for the central passage on the clamping shank side, the inlet passages, the coolant pipes, the outlet passages and the central outlet opening to have a cross section of flow which is substantially constant or, in sections, increases or decreases continuously.
According to a preferred configuration of the invention, the seal on the hollow shank side is designed as an axial seal. This arrangement has the advantage that the seal cannot be damaged during a tool change. It is also possible to provide a lip seal at that location, the sealing lip of which can be pressed against a base surface or a lateral surface of the recess on the hollow shank side under the action of the coolant pressure. If pressure is therefore applied to the tool head by means of coolant via a passage on the clamping shank side after the coupling operation, the centering cage is displaced, under the action of the coolant, toward the tool head, so that the centering element on the hollow shank side comes into contact with its seal. A further improvement in this respect is achieved by the fact that a spring member which presses the centering cage gently toward the tool head is arranged between the clamping shank and the centering cage. The spring member may in this case be designed as a helical compression spring which is arranged in a cylindrical recess in the clamping shank and is gently preloaded between the clamping shank and the centering element on the clamping shank side. The gentle preloading is to be selected in such a way that the centering cage is reliably displaced toward the tool head while, nevertheless, it does not present any significant resistance during the clamping operation.
The centering element on the clamping shank side may have an axially central pocket for holding ends, on the clamping shank side, of the clamping elements, which ends project axially beyond the clamping insert in such a manner that they float in the axial and radial directions.
A significant advantage of the clamping insert with split clamping elements consists in the greater ease of assembly and dismantling with a prefabricated centering cage. The clamping elements are expediently fitted releasably into the prefabricated centering cage.
To make it easier to introduce the hollow shank into the hollow-shank seat of the clamping shank, it is proposed, according to a preferred configuration of the invention, for a spring element which preloads the centering cage in the direction of the clamping shank to be arranged between the clamping insert and the centering cage. The spring force of the spring element is to be selected in such a way that the forces acting on the centering cage under the action of the coolant pressure are able to overcome the spring force. The spring element may at the same time be designed as a centering member for the clamping insert. In particular, the spring element may be designed as a helical compression spring, one end of which
Browne Lynne H.
Cottingham John R.
Flynn ,Thiel, Boutell & Tanis, P.C.
Komet Praezisionwerkzeuge Robert Breuning GmbH
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