HOLDER FOR INSERTS FOR SLOT MILLING CUTTERS

Abstract: Holder for insert at milling heads and the like, wherein at a free end face for the milling head (1) are arranged a number of shallow recesses (3) corresponding to the intended number of insert (6) said recess having an inner portion (13) inside a restriction (12) and in an outer radially outwardly open portion (11) a side having a seat (5) adapted to the abutment side of the insert and a threaded bore (8) in the bottom of the recess, wherein the clamping body (14) besides a projection (20) intended to engage an insert (6) placed at the abutment portion (5), has an inwardly extending portion (22) inside a neck portion said head portion having a cross extension wider than the width over the narrowing (12) of the recess and wherein the bore is so localised relative to a hole in the clamping body, which hole has conical abutment surface, that a screw having a conical head (18) threaded into the bore (8) on reaching engagement with said conical abutment surface will displace the clamping body laterally so that the insert will be securely held against its abutment portion simultaneously by the engagement between the side surface of the head and an obliquely arranged wall portion of the clamping body will be pulled inwardly towards the center of the milling head.

Description: Holder for inserts for slot milling cutters. Technical field of the invention This invention relates especially to holders for milling cutters and the like, i.e. arrangements for holding one or more cutting insert at a normally rotatable milling head wherein the insert or the inserts project radially from the milling head in order to allow the use thereof for milling a slot in a work piece. Background of the invention Milling cutters having replaceable inserts are known since long time. One problem with known fastening and tightening devices at milling heads is that they need unacceptable large space especially in a direction towards or in the area at the free end of the milling head. Uptil now known constructions have neither given any acceptable solution of the problem of arranging essentially radially localised inserts immediately at the end face of the milling head and to utilise for such purposes small inserts of the kind more and more used today. One example of a known milling cutter having replaceable inserts is shown in GB, B, 1 500 556. In the known arrangement each insert has a considerable axial length allowing the use of a rather wide and bulky clamp means loosely inserted into an outer cut away portion at the periphery of the milling cutter and arranged by means of a tangentially oriented screw engaging one side of the cut to be swung or pivoted towards an insert placed between an abutment at the opposite side of the cut around a head shaped projection of the clamp means inserted into an inner cut away portion and serving as a fulcrum for the entire clamp means. The known arrangement can be used for milling tools with inserts having a pronounced axial length as the screw arrangement demands a rather wide or thick clamp means and peripheral accessability. It is, accordingly not possible to use the known arrangement for milling tools having narrow or thin radially protruding edged inserts of a type similar to the one used in connection with parting tools on turning operations at lathes. From other field of the art is known an arrangement for fastening of replaceable teeth at circular saws. U.S. Patent No. 785,583 discloses a circular saw having at its periphery a number of cuts defined by essentially radial side edges one of which protrudes circumferentially over part of the radially facing mouth of the cut to form an inwardly facing radial abutment. An essentially V shaped locking body is inserted into the cut, the inner end of such body movable received in a curved inner end of the cut, one leg of the body fitted inside the circumferentially protruding edge portion and being biassed by a wedge means radially movably inserted between said one leg and the one side of the cut, the other leg being arranged to engage a tooth insert placed between a seat at the other side of the cut and the said leg. On pressing or moving the wedge means the one way or the other, the locking body will be swung around its innermost portion to press or release the tooth insert towards and from respectively the opposide edge of the cut. None of the known arrangements ensures a stability and exactness necessary for milling tools of the type herein referred to. One aspect of the invention is to bring about a holder making it possible to use the small inserts also for radial positioning at milling heads where the inserts will be close to a free end face of the milling head. Summary of the invention Behind this invention lies the knowledge that inserts of the kind normally used on turning preferably for parting of work and cutting of slots, because of their narrow width would be very useful for milling purposes, e.g. on machining operations close to a face or corner where conventional milling heads do not reach. According to the invention there is at the end face of a milling head or the like tool arranged a number of recesses corresponding to the intended number of inserts, such recesses being defined by walls or edges parallel with the rotational axis of the milling head one such a wall presenting a shape complimentary to the abutment face of the insert and such walls defining an outer portion opening radially and in one direction defined by the said abutment portion and one inner portion by a restricted passage communicating with the outer portion, wherein the inner portion on the same side as the abutment face has an obliquely arranged inwardly inclined wall portion. In each such recess arrangement there is a clamping body having a hook like projection intended to engage the abutment side of the insert and one head like projection connected therewith by a narrow neck portion and adapted to be received inside the inner portion of the recess; an edge portion of such clamping body head portion facing the inclined wall portion of the recess. Each clamping body receiving recess has at the bottom of the outer recess portion a threaded bore and the clamping bodies have each a conically hole for a receiving conically arranged head of a screw means to be threaded into the said bottom bore and the hole is so localised that by inserting the screw and allowing the head of the screw to engage the conical hole of the clamping body the latter will be moved sidewardly and in this way clamps an insert placed between the clamping body and the abutment portion of the outer recess. Simultaneously the engagement between the clamping body head portion and the inner recess portion allows the clamping body to swing inwardly towards the inner portion thereby also applying an inwardly directed pulling force on to the insert. Brief description of the drawings The invention will be described in details below with references to the attached drawing, on which Figure 1 is a schematic end view of a milling head arranged with holders for radially oriented cutting inserts, Figure 2 is a sectional view through the cutting head according to Figure 1. A milling head is designated 1 and it has at its free end edge a flange like portion 2 like a flange protruding around the head proper. At the end face of the milling head there are a number, in the shown example four, recesses 3 and these have an axial depth which essentially corresponds with the width of the cutting inserts here. The recesses open radially outwardly by cuts 4 at the flange. One side of each recess and cut is shaped for forming a guiding and seat portion 5 for one per se known insert 6 and has therefore an essentially radially arranged V-groove, the majority of which is at the protruding edge flange 2. At the bottom of each recess there is a threaded bore 8 and in a wall portion adjacent the abutment portion a seat 9 for a spring 10. Each recess is formed by an outer portion 11 and an inner portion 13 with an intermediary narrowing 12. One clamp body designated 14 is intended to coact with each recess in order to clamp the insert 6 and this clamping body has an opening 16 with a conical surrounding surface 15 through which a tightening screw 17 with a head 18 having a conical abutment face 19 is intended to run. The clamping body 14 has a protruding notch 20 intended to engage the free side of the insert shaft and has besides that a head portion 22 and an intermediary neck portion 21, the shape of the head portion adapted to fit into the inner portion of the recess and allow movements of the head portion inside the same. Accordingly the inner recess portion has adjacent the narrowing 12 an obliquely arranged inwardly sloping wall portion 23 and the portion 24 of the clamping body localised adjacent same is intended to engage such wall portion. The threaded bore 8 is so localised relatively to the hole 16 for the screw head at the clamping body that on tightening the screw the clamping body 14 will be displaced by a large force towards one insert 6 placed at the abutment portion 5 and towards the same side of the narrowing 12. In this way the insert will be pressed firmly against its abutment portion and simultaneously, because of the interaction between the clamping body head portion and the obliquely arranged wall portion 23 adjacent the narrowing 12 be subjected to an inwardly pulling force pulling the clamping body and the insert 6 inwardly towards the center of the milling head. The clamping body 14 only touches the milling head at two points, at the insert and at the obliquely arranged 23, simultaneously as its outer portion is biassed by the tightening screw. This results in a safe stable holding of the insert which also is secured against pulling movements radially out wardly. The invention is not to be regarded as limited to the embodiment described and shown on the drawings but can be modified in a number of ways within the scope of the following claims.

Claims: CLAIMS 1. Holder for cutting inserts for milling cutters and the like tools, especially for the milling of slots, including the milling cutter head, abutment portions arranged thereon, clamping means for engaging the inserts and tightening means for same, wherein a number of recesses (3) corresponding to the given number of cutting inserts (6) are arranged at a free end face of the cutter head (1), each such recess having an axial depth essentially corresponding to the width of each cutting insert (6), and formed by an inner portion (13) closed but for a narrow connection (12) towards an outer portion (11) open radially outwardly, said outer portion having at one side thereof a seat portion (5) for a cutting insert and being adapted to receive a clamping body (14) with a head like projection to be received in the inner recess portion (13), a neck portion engaging the narrow connection and an abutment portion at the clamping body for engaging a cutting insert, c h a r a c t e r i z e d in that each of the recesses (3), which is shallow in the axial direction and adapted to receive a cutting insert (6) for cutting slots and the like, has an obliquely arranged edge or wall portion adjacent the narrow connection between the recess portions, intended for cooperation with an edge portion of the clamping body (14), that the bottom of the recess presents a threaded bore for a screw means to be fitted through a hole in the clamping body, the edge of said hole as well as the lower side of the head (18) of the screw means to be inserted into said hole being conical, and that the dimensions and the localization ot the threaded recess bottom bore and the clamping body hole, the obliquely arranged recess edge and the opposing clamping body edge, the neck portion and restricted portion (12) , respectively being such that on tightening of the screwmeans the clamping body edge portion engaging the obliquely arranged recess edge portion causes the clamping body (14) to pivot over the neck and restricted portion (12) to press the cutting insert (6) towards the recess seat portion (5). 2. Holder according to claim 1, c h a r a c t e r i z e d by a seat or the like for a spring arranged at a wall portion adjacent the outer recess portion at the same side as the abutment portion (5) for the insert, said spring intended to counteract the engagement between the conical head of the screw and the conical surface around the hole resulting in lateral displacement of the clamping body (14) . 3. Holder according to claim 1 or 2, c h a r a c t e r i z e d in that the size of the clamping body head (22) is so adapted relatively to the size of the inner recess portion (13) that the head and thereby also the clamping body can be displaced in different directions but that the cross extension of said head portion is larger than the width of the restriction.

Inventors: WLAJKO MIHIC, WLAJKO, MIHIC
Applicants: MIRCONA AB
Application year: 1992
Main classification: B23C5
IPC codes: B23C5