Cutters – for shaping – Including holder having seat for inserted tool – With separate means to fasten tool to holder
Patent
1996-06-07
1998-09-08
Howell, Daniel W.
Cutters, for shaping
Including holder having seat for inserted tool
With separate means to fasten tool to holder
407110, 407109, B23B 2704
Patent
active
058036750
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This is a national phase of PCT/DE94/00975 filed 20 Aug. 1994 and based upon a German National Application G 93 17 533.7 filed 16 Nov. 1993 under the International Convention.
The invention relates to a holder for chip-removal tool inserts, particularly a piercing or cutting insert, held in a clamping slot and whose oppositely located clamping jaws have a slot area of an elongated shape wherein an expansion key with elliptical or oblong-oval cross section can be inserted and can be rotated thereby expanding the opposite jaws.
BACKGROUND OF THE INVENTION
Such holders are known for instance from the DE 39 06 822 C2 or the EP 0 095 062 B1. In the mentioned European patent specification the expansion of the clamping jaws in relation to each other is accomplished by inserting and turning an elliptic key in the ovally shaped area of the clamping slot. A disadvantage of this embodiment indicated in DE 39 06 822 C2 consists in that the precise geometrical shape of the oval slot area is not closer specified and therefore in this holding system an excessive expansion of the clamping slot, surpassing the elastic limits of the material, can not safely be avoided. Moreover for avoiding permanent deformation, particularly of the oppositely located clamping jaws, with the result that a stable clamping of the tool inserts can no longer be insured, as well as for facilitating the insertion and/or turning of the key bit, an oval slot area has to be provided in the holder, consisting of two recesses, each located in one of the opposite jaws, correspondingly to the two smaller vertex curvature circles of the elliptic cross section profiles and are at a distance from each other ranging approximately between the lengths of the bigger and the smaller ellipse axis. The disadvantage is that in this embodiment of the holder the guidance of the expansion key is not optimal.
Further from the DE-A-30 44 790 an ejection lever with an oblong-rounded attachment piece is known, which can be inserted in a circular recess limiting the clamping slot towards the rear. Here too the optimal guidance of the ejection lever is deficient during the ejection of the cutting insert.
Furthermore mountings for cutting inserts in disk milling cutters are known, which are arranged in a clamping slot which has a rear extension, located behind the clamped cutting insert. For the exchange of the cutting inserts a key is provided, whose first tongue is meant to engage in the mentioned extension, and the second, parallel tongue engages on a radial frontal surface of the disk-like mounting. The drawback of this system consists in the required long lever arm, which leads to a high radial stress load on the mentioned tongues and the danger of bending. Moreover a high expansion force is to be applied, which can damage the holder. A controlled release of the clamping stress is barely possible.
OBJECT OF THE INVENTION
It is the object of the present invention to further develop a holder of the kind mentioned in the introduction, so that during expansion of the laws the expansion key can be guided in a stable, safe and slide-resistant manner, while it still remains easy to handle.
SUMMARY OF THE INVENTION
This object is achieved due to the holder according to the invention and is characterized in that the elongated slot area has oppositely located part-circular enlargements, the distance between their vertices being smaller than the biggest distance between the elliptic or oblong-oval cross section profiles. Such enlargement can be created by drilling in the elongated slot area. The advantage over oblong-oval enlargements with flat or such limit surfaces, whose curvature radius is considerably bigger than the respectively effective radius of the expansion key, consists in the noticeably improved guidance of the expansion key. Also from the manufacturing point of view, such enlargements are easier to make than oval or oblong enlargements.
Advantageously when the expansion key is inserted, the transition points where th
REFERENCES:
patent: 3191262 (1965-06-01), Gustafson
patent: 3785021 (1974-01-01), Norgren
patent: 4357123 (1982-11-01), Zweekly
patent: 5035545 (1991-07-01), Zinner
Dubno Herbert
Howell Daniel W.
Kateshov Yuri
Widia GmbH
Williams Mark
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