Chucks or sockets – Socket type – Lost motion
Reexamination Certificate
1999-05-06
2001-01-30
Bishop, Steven C. (Department: 3722)
Chucks or sockets
Socket type
Lost motion
C279S074000, C279S082000, C279S029000, C279S904000
Reexamination Certificate
active
06179300
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a tool holder for coupling of rotatable and/or striking tools with hand power tools, in particular with drill hammers or impact hammers.
In a known tool holder disclosed for example in the German patent document DE 32 05 063 C2 the tool shaft has two open driving grooves located at diametrically opposite points and having radial flanks which cooperate with associated surfaces of stripped shape drivers in the receiving opening of the coupling sleeve which receives the tool shaft. Two groove-shaped locking pockets which are closed at both sides in the axial direction are provided on the diagonals which are perpendicular to the diametrical points, on the outer surface of the tool shaft. They are used for axial holding of the tool in the tool holder. The locking bodies engage in the locking pockets and are formed as balls. The balls abut against a flat sheet metal ring which is supported on the displacement sleeve, in the part of the displacement sleeve located in immovable position in which the blocking surface is provided. Therefore, the balls are secured against radial displacement from the blocking pockets. For unlocking the tool, the displacement sleeve is displaced against the spring force so that the balls reach a region of the displacement sleeve located outside of the blocking surface, in which the balls are released for a radial displacement. During removal of the tool shaft from the coupling sleeve, the balls are moved from the locking pockets and the tool shaft is released. During insertion of the tool the end of the tool shaft presses the balls against the sheet metal ring and displaces the same until the balls leave the blocking surface of the displacement sleeve and can deviate radially outwardly, so that the tool shaft can be displaced under the balls. When the locking pockets reach the balls, the balls dig into the locking pockets, and the springs which were tensioned during the insertion step by displacement of the sheet metal ring are displaced under the blocking surface. The tool is thereby axially fixed in the tool holder with a gap in the axial direction.
In another known tool holder disclosed for example in the German patent document DE 35 06 008 C2 the torque transmission from the tool holder to the tool shaft is not performed through special drive grooves in the tool holder, but instead is performed through locking pockets. For this purpose the locking body engages the longitudinally extending cylindrical rollers which engage form-lockingly in the locking pockets with closed end sides, and the tool shaft is fixed both in the axial direction as well as in the rotary direction in the coupling sleeve. For removing the cylindrical rollers from the locking pockets, the displacement path in the displacement sleeve must be greater than the length of the cylindrical rollers, which must be as long as possible for transmission of a great torque. In order to shorten the displacement path, each locking body which is formed of two parts has a sliding block with an abutment projection near the cylinder roller. The blocking surface of the sliding sleeve is stepped and provided with two radially offset control surfaces, which cooperate also with two radially stepped surface portions of the periphery of the sliding block. The sliding block is located on the associated cylindrical roller and over engages with its radial abutment projections the end side of the cylinder roller which is located behind in the insertion direction of the tool shaft. A pressure spring which acts against the insertion direction of the tool shaft loads the sliding block in an axial direction and presses it against an abutment on the displacement sleeve.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a tool holder, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a tool holder in which each locking body in a longitudinal section has a saddle construction with two humps which are spaced from one another, abut against the blocking surface and have an arcuate cross-section, and with a long shaped body which extends at the side facing away from the hump and has a region inserted in the locking pocket and having a cross-section which form-lockingly corresponds to the cross-section of the locking pocket, and the locking surface of the displacement sleeve has at least one ring groove which allows the insertion of a hump and is formed with a groove depth which is greater than a radial depth of the locking pockets.
When the tool holder is designed in accordance with the present invention, the locking pockets are used for increased torque transmission, the displacement sleeve for its simple handling requires during an axial unlocking actuation a small displacement path of several millimeters for the tool unlocking, and despite this the locking bodies have a design which provides their simple manufacture.
The locking bodies are composed of a single part and have a symmetrical construction, which increases the manufacturing and mounting safety. The contact surfaces between the locking bodies and the blocking surface on the displacement sleeve can be made very small by the corresponding design of the hump in the axial direction and reduced to a line. This makes possible a low-friction free rotation of the displacement sleeve relative to the coupling sleeve in the event of an end-side wall contact, which substantially increases the safety in the handling of the power tool.
In accordance with a preferable embodiment of the invention, the flanks of the saddle surface which connects one hump to the other in the locking body has a definite flank angle, and the groove flanks are provided with at least one ring groove with a same flank angle. A radially outwardly arranged incline is formed at both ends of the blocking surface and extends at a same angle of the hump flanks. During locking and unlocking of the tool, a hump flank of the locking body comes to abutment with a groove flank or an incline of the blocking surface. Due to these flanks which abut against one another, the blocking body during unlocking and locking step turns around one hump definitely, whereby a tilting of the locking body and a resulting poor availability during insertion and withdrawal of the tool from the tool holder is avoided.
In accordance with a further preferable embodiment of the invention, the blocking surface of the displacement sleeve at its rear end as considered in the insertion direction of the tool shaft is limited by an axially displaceable ring-shaped holding disk. The holding disk engages with a radially inwardly projecting holding projection into a longitudinal passage in the coupling sleeve and abuts by a locking spring with a pressure force opposite to the insertion direction of the tool shaft against a radial shoulder of the displacement sleeve formed on the end of the blocking surface. This blocking sleeve guarantees the automatic return of the locking body to the locking position after a complete insertion of the tool shaft into the coupling sleeve.
In accordance with a preferable embodiment of the invention, the holding disk is composed of a springy material, for example a spring metal sheet and the holding projections are cut from the disk ring by at least one slot so that they can spring in the axial direction opposite to the disk plane. With such a holding disk which is supported by the locking spring between the displacement sleeve and the coupling sleeve, the pressure spring for axial spring loading of the displacement sleeve can be dispensed with, since the holding metal sheet of the locking sleeve takes over the both different return functions for the disk sleeve and the locking body, without releasing a similarly oriented displacement movement of the displacement sleeve during the axial displacement of the locking body released by insertion of the tool shaft into the
Baumann Otto
Kageler Sven
Bishop Steven C.
Robert & Bosch GmbH
Striker Michael J.
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