Tool for parting and grooving

Details Tool for parting and grooving Tool for parting and grooving

2000-02-02

2001-08-07

Tsai, Henry (Department: 3722)

Cutters, for shaping

Including holder having seat for inserted tool

With separate means to fasten tool seat to holder

C407S110000, C407S117000

Reexamination Certificate

active

06270294

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a tool coupling of the kind that comprises a holder and an adapter for at least one cutting machining element, said adapter including a first serration intended to co-operate with a second serration of the holder, more precisely by bringing the serrations to engage each other by means of a clamping means while providing a torque resistant connection between the adapter and the holder. More specifically, the present tool is intended for parting and grooving operations.
Within the field of chip removing machining there are tool couplings of the general kind defined above for use in several different applications, however, usually in turning tools of different type. Thus under the trade name COROMANT CAPTO
â
(Manufacturer: Sandvik AB, Sweden) boring bars are marketed, said boring bars having such couplings. The holder constitutes for instance a bar for a cutting head mountable in a multi-purpose lathe, said cutting head having one or more machining elements in the shape of exchangeable inserts. In connection with previously known boring bars of this kind a first serration is provided at an essentially planar inner end surface of the cutting head, while a co-operating second serration is provided at an external or free end surface of the bar. In order to bring the serrations into engagement with each other several loose screws are used as clamping means, said screws having an enlarged head and being tightened in axial threaded holes that open in the serrated surface of the free end of the bar. More precisely, in this end surface of the bar, four equidistant separated holes are recessed, of which both of the two upper holes receive screws that are inserted through holes formed in the cutting head, and one or the other of the two lower holes receives a screw, depending on whether the cutting head in question is of a left-hand type or a right-hand type.
By the presence of the above-mentioned serrations in the two end surfaces of the bar and the cutting head respectively, said serrations being urged against each other, a very reliable, torque resistant connection is achieved between the bar and the cutting head. This in turn guarantees that the active insert is given and maintains a correct position. However, a disadvantage in connection with the previously known tool coupling is that the exchange of the cutting head is complicated and time-consuming. Thus, not less than three screws must initially be loosened and then again tightened to complete a tool exchange, which might take several minutes. The tool exchanges become especially difficult in such cases when the screws are hard to reach and/or have chips, dirt, grease deposits or the like in their key recesses. Under such circumstances the operational shutdowns for tool exchanges may be very time-consuming and expensive. Further, there is a risk that screws are lost since they must be loosened completely in order to allow dismounting of the cutting head.
A tool coupling using co-operating serrations in combination with screws such as clamping means in parting tools is disclosed in Swedish Patent Application No. 7813038-2. In this case the number of screws for clamping the adapter and the holder is three. This means that the activity of first disengaging three comparatively long screws and subsequently tightening them again when insert change is needed for indexing a new cutting edge, is very time consuming. Further, there is a risk that screws become lost since they must be loosened completely.
OBJECTS AND FEATURES OF THE INVENTION
The present invention aims at removing the shortcomings mentioned above in connection with previously known tool couplings of the type in question and at providing an improved coupling. Thus, a primary object of the invention is to create a tool coupling by means of which the necessary cutting insert exchanges are effected in a quick and simple way without dismounting each clamp screw in its entirety. A further object is to create a tool coupling that makes it possible to design one and the same holder in such a way to allow dismounting without a risk that the clamp screws are lost. Still a further object of the invention is to create a tool coupling where during dismounting there is no need for separate key means.
According to the invention at least the primary object is attained by a tool which comprises a holder, an adapter, and fastener screws. The holder includes a serrated holder surface, and a plurality of threaded holes extending into the serrated holder surface. The adapter is mounted on the holder. The adapter is thinner than the holder and includes a serrated adapter surface meshing with the serrated holder surface to provide a torque-resistant connection between the adapter and the holder. The adapter further includes a forward slot formed between a support portion and a clamp portion of the adapter. Through-holes extend through the adapter and are aligned with respective ones of the threaded holes. A rear slot extends through a first of the through-holes to render the clamp portion elastically movable. The first through-hole has a conical entry surface. The fastener screws extend through respective ones of the through-holes and are threaded in respective ones of the threaded holes for securing the adapter to the holder. A first of the screws extends through the first through-hole and includes a conical head engaging the conical entry surface such that a tightening of the first screw displaces the clamp portion toward the support portion.


REFERENCES:
patent: 3205557 (1965-09-01), Frommelt et al.
patent: 4235564 (1980-11-01), Huser
patent: 4580930 (1986-04-01), Zinner
patent: 4887945 (1989-12-01), Pano
patent: 4938641 (1990-07-01), Maier
patent: 5267817 (1993-12-01), Englund
patent: 5829923 (1998-11-01), Nowicki

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