Tool holder having a clamping member with a non-circular cross-section and method for clamping a cutting insert therein

A tool holder has a main body with a holder head extending away from a holder shank, the holder head having an insert receiving pocket at a forward end thereof, with a pocket support surface. A clamping member is retained in the holder head, the clamping member comprising a clamping shaft longitudinally extending along a shaft axis. A locking member operatively engages an abutment surface of the clamping shaft. The shaft axis does not intersect the pocket support surface, and the clamping shaft has a non-circular shape in a cross-section taken perpendicular to the shaft axis. The tool holder is configured to direct a clamping force towards, and clamp a cutting insert against, the pocket support surface.

FIELD OF THE INVENTION

The present invention relates to a tool holder for use in metal cutting processes in general, and for grooving, turning and parting operations in particular.

BACKGROUND OF THE INVENTION

Within the field of tool holders used in grooving, turning and parting operations there are many examples of cutting inserts being clamped in an insert receiving pocket of a tool holder having an upper pocket clamping surface and a lower pocket support surface. Some of these tool holders are configured such that a clamping force is actively applied to clamp the cutting insert between the upper pocket clamping surface and the lower pocket support surface.

U.S. Pat. No. 5,360,298 discloses such a tool holder, having a clamping member in the form of a clamping screw. The clamping screw passes through a through bore in an upper part of the tool holder associated with the upper pocket clamping surface, bisects a clamping slot extending rearwardly from the insert receiving pocket, and engages a threaded bore in a lower part of the tool holder associated with the lower pocket support surface. The clamping screw is tightened in order to clamp the cutting insert in the insert receiving pocket.

U.S. Pat. No. 6,814,526 also discloses such a tool holder, having a clamping member in the form of a drawbar and a locking member in the form of a locking screw. The drawbar comprises a head and a cylindrical shaft, the cylindrical shaft having a threaded end portion distal from the head. The cylindrical shaft bisects a clamping slot extending rearwardly from the insert receiving pocket and is threadingly retained in an upper part of the tool holder associated with the upper pocket clamping surface. The head is located in a lower part of the tool holder associated with the lower pocket support surface, and the locking screw operatively engages the head to clamp the cutting insert in the insert receiving pocket.

U.S. Pat. No. 6,139,227 also discloses such a holder, having a clamping member in the form of a transmission pin and a locking member in the form of an eccentric cam. The transmission pin is slidably retained in a first bore in a lower part of the tool holder associated with the lower pocket support surface. The first bore intersects a clamping slot located rearward of the insert receiving pocket, above which is situated an upper part of the tool holder associated with the upper pocket clamping surface. The eccentric cam is located in a second bore transverse to the first bore in the lower part of the tool holder, and operatively engages the transmission pin to clamp the cutting insert in the insert receiving pocket.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a tool holder comprising:

a main body having a holder head extending away from a holder shank, the holder head having an insert receiving pocket at a forward end thereof, with a pocket support surface;

a clamping member retained in the holder head, the clamping member comprising a clamping shaft longitudinally extending along a shaft axis; and

a locking member operatively engaging an abutment surface of the clamping shaft,

wherein the tool holder is configured to direct a clamping force towards, and clamp a cutting insert against, the pocket support surface,

wherein the shaft axis does not intersect the pocket support surface, and

wherein the clamping shaft has a non-circular shape in a cross-section taken perpendicular to the shaft axis.

Further in accordance with the present invention, there is provided a tool holder assembly comprising:

a main body having a holder head extending away from a holder shank in a forward direction, the holder head having an insert receiving pocket at a forward end thereof, the insert receiving pocket having a pocket support surface and an opposing pocket clamping surface;

a clamping bore formed in the main body and extending along a clamping axis, the clamping axis not intersecting the pocket support surface and the clamping bore having a non-circular shape in a cross-section taken perpendicular to the clamping axis;

a locking bore formed in the main body and intersecting the clamping bore;

a clamping member configured to be received in the clamping bore, the clamping member having a clamping shaft with an abutment surface; and

a locking member configured to be received in the locking bore and operatively engage the clamping shaft's abutment surface when the clamping member is received into the clamping bore, to thereby apply a clamping force which urges the pocket clamping surface towards the pocket support surface.

A cutting tool in accordance with the present invention may thus comprise the aforementioned tool holder assembly; and

a cutting insert clampingly retained in the insert receiving pocket between the pocket support surface and the pocket clamping surface.

Also in accordance with the present invention, there is provided a method of assembling a cutting tool comprising the aforementioned tool holder assembly and a cutting insert, the cutting insert having opposing first and second insert surfaces with an operative cutting edge associated with the first insert surface. The method comprises the steps of:

positioning the cutting insert adjacent the forward end of the holder head with a portion of the second insert surface in contact with the pocket support surface,

sliding the cutting insert in a generally rearward direction into the insert receiving pocket, and

actuating the locking member until a clamping force is applied between the second insert surface and the pocket support surface.

DETAILED DESCRIPTION OF THE INVENTION

Attention is first drawn toFIGS. 1 and 2, showing a cutting tool20in accordance with some embodiments of the present invention. The cutting tool20comprises a laterally slim tool holder22with a cutting insert24removably secured therein.

As shown inFIGS. 3 and 4, the tool holder22, which may be manufactured from hardened steel, has a main body26with a holder head28extending away from a holder shank30in a forward direction F, and the holder head28has an insert receiving pocket32at a forward end34thereof, with a pocket support surface36.

In some embodiments of the present invention, the holder head28may be rigidly fixed to the holder shank30.

Also, in some embodiments of the present invention, as shown inFIG. 5, the pocket support surface36may be generally V-shaped when viewed from a position forward of the insert receiving pocket32.

According to the present invention, as shown inFIG. 2, the tool holder22is configured to direct a clamping force f towards, and clamp the cutting insert24against, the pocket support surface36.

As shown inFIGS. 1 and 2, the cutting insert24, which may be manufactured by form press and sintering a cemented carbide, has opposing first and second insert surfaces38,40, with an operative cutting edge42associated with the first insert surface38, and the second insert surface40in clamping contact with the pocket support surface36.

According to the present invention, as shown inFIG. 3, a clamping member44is retained in the holder head28, the clamping member44comprising a clamping shaft46longitudinally extending along a shaft axis A1.

In some embodiments of the present invention, the clamping member44may be received in a clamping bore48in the holder head28and non-threadingly retained therein.

Also, in some embodiments of the present invention, the clamping shaft46may be slidably retained in the clamping bore48.

Further, in some embodiments of the present invention, the clamping shaft46may be slidable solely in a direction along its shaft axis A1.

According to the present invention, as shown inFIGS. 7, 8, 11 and 12, the clamping shaft46has a non-circular shape in a cross-section taken perpendicular to the shaft axis A1.

In some embodiments of the present invention, as shown inFIGS. 4, 7 and 8, the clamping bore48may extend along a clamping axis A2and have a non-circular shape in a cross-section taken perpendicular to the clamping axis A2.

Also, in some embodiments of the present invention, as shown inFIGS. 7 and 8, the clamping axis A2may be coaxial with the shaft axis A1, and the clamping bore48may have a non-circular shape corresponding to the shape of the clamping shaft46in a cross-section taken perpendicular to the clamping axis A2and/or the shaft axis A1.

Further, in some embodiments of the present invention, the clamping shaft46may have a non-circular shape in a cross-section taken perpendicular to the shaft axis A1along the whole of its length.

Yet further, in some embodiments of the present invention, the clamping shaft46may have identical profiles in two cross-sections taken perpendicular to the shaft axis A1at opposing shaft ends50a,50bthereof.

According to the present invention, as shown inFIGS. 5 and 6, a locking member52operatively engages an abutment surface54of the clamping shaft46.

In some embodiments of the present invention, the locking member52may operatively engage a single abutment surface54of the clamping shaft46.

Also, in some embodiments of the present invention, as shown inFIG. 10, the abutment surface54may intersect an outer peripheral surface56of the clamping shaft46.

Further, in some embodiments of the present invention, as shown inFIGS. 11 and 12, the abutment surface54may not be visible in each end-view of the clamping member44taken axially along the shaft axis A1.

By virtue of the clamping bore48having a non-circular shape corresponding to the shape of the clamping shaft46in a cross-section taken perpendicular to the clamping axis A2and/or the shaft axis A1, the clamping shaft46may be non-rotatable about its shaft axis A1, including when the locking member52is not engaged to the abutment surface54of the clamping shaft46, such as when the locking member52is removed from the tool holder22.

The clamping shaft46being non-rotatable about its shaft axis A1results in reliable operative engagement between the locking member52and the abutment surface54, which beneficially contributes to the high level of clamping repeatability.

In some embodiments of the present invention, the locking member52may be received in a locking bore58in the holder head28, and threadingly retained therein.

Also, in some embodiments of the present invention, the locking bore58may intersect the clamping bore48.

As shown inFIGS. 5 and 6, the abutment surface54may be entirely located on one side of a shaft plane P1containing the shaft axis A1.

In some embodiments of the present invention, the clamping shaft46may exhibit mirror symmetry about the shaft plane P1, such that the clamping shaft46has one abutment surface54located on each side of the shaft plane P1and a total of two abutment surfaces54.

Also, in some embodiments of the present invention, as shown inFIGS. 5 to 8, the locking member52occupied in the locking bore58may be entirely located on one side of the shaft plane P1.

Further, in some embodiments of the present invention, as shown inFIGS. 5 to 8, the locking bore58may have a locking axis A3perpendicular to the shaft plane P1, and the locking bore58may intersect at least one of two opposing outer lateral surfaces60a,60bof the laterally slim holder head28.

For embodiments of the present invention, where the clamping shaft46exhibits mirror symmetry about the shaft plane P1, the locking bore58, although ‘interrupted’ by the clamping bore48, may extend towards and open out to both of the outer lateral surfaces60a,60b, thus allowing the locking member52to operatively engage with either of the two mirror symmetrical abutment surfaces54and the operator to access the locking member52from either of the two outer lateral surfaces60a,60b.

In some embodiments of the present invention, as shown inFIGS. 5 and 6, the locking axis A3may be perpendicular to the clamping axis A2and/or the shaft axis A1.

Also, in some embodiments of the present invention, as shown inFIG. 4, the clamping bore48may have a minimum bore width WBMINin a direction along the locking axis A3.

The ‘non-circular shaped’ clamping bore48having its minimum bore width WBMINin the direction along the locking axis A3advantageously provides sufficient space for the routing of a coolant duct80between the clamping bore48and one of the outer lateral surfaces60b.

In some embodiments of the present invention, as shown inFIGS. 4, 7 and 8, the clamping bore48may be oblong shaped in a cross-section taken perpendicular to the clamping axis A2.

As shown inFIGS. 5, 6 and 8 to 10, the abutment surface54may form a portion of a frusto-conical shaped shaft recess62extending along a recess axis A4, and the recess axis A4may be perpendicular to the shaft plane P1.

In some embodiments of the present invention, as shown inFIG. 10, the clamping member44may include a clamping head64at one shaft end50bof the clamping shaft46, the shaft recess62may have a recess plane P2containing the recess axis A4and perpendicular to the shaft axis A1, and the clamping head64and the abutment surface54may be located on opposite sides of the recess plane P2.

Also, in some embodiments of the present invention, as shown inFIGS. 11 and 12, the clamping shaft46may exhibit 180° rotational symmetry about the shaft axis A1.

Further, in some embodiments of the present invention, as shown inFIGS. 11 and 12, the clamping head64may not exhibit 180° rotational symmetry about the shaft axis A1.

As shown inFIG. 10, the clamping head64may have a head under surface66immediately adjacent the clamping shaft46facing towards the recess plane P2.

In some embodiments of the present invention, the head under surface66may be substantially planar and perpendicular to the shaft axis A1, and the abutment surface54may face towards a head plane P3containing the head under surface66.

As shown inFIGS. 5 and 6, the recess axis A4may intersect the shaft axis A1and/or the clamping axis A2, and the abutment surface54may form an external acute abutment angle α with the recess axis A4.

In some embodiments of the present invention, the abutment angle α may be less than 45° and greater than 20°.

As shown inFIG. 11, the clamping shaft36may have a maximum shaft width WSMAXin a direction perpendicular to the shaft axis A1and the recess axis A4.

The ‘non-circular shaped’ clamping shaft36having its maximum shaft width WSMAXperpendicular to the recess axis A4advantageously provides the clamping shaft36with high tensile strength in the vicinity of the shaft recess62, as well as along the shaft's length.

In some embodiments of the present invention, as shown inFIGS. 7 and 8, the clamping shaft46may be oblong shaped in a cross-section taken perpendicular to the shaft axis A1.

Also, in some embodiments of the present invention, as shown inFIGS. 6 and 11, the clamping shaft46may have a minimum shaft width WSMINin a direction along the recess axis A4and the shaft recess62may have a recess depth D1in a direction along the recess axis A4, and the recess depth D1may be greater than a third of the minimum shaft width WSMIN. As best seen inFIGS. 4, 7 and 8, the clamping member44is retained in the holder head28such that the minimum shaft width WSMINextends principally in a width direction WH of the holder head28perpendicular to the forward direction F, as does the minimum bore width WBMIN.

A method of clamping the cutting insert24in the tool holder22comprises the steps of:

positioning the cutting insert24adjacent the forward end34of the holder head28with a portion of the second insert surface40in contact with the pocket support surface36,

sliding the cutting insert24in a generally rearward direction R into the insert receiving pocket32, and

actuating the locking member52until the clamping force f is applied between the second insert surface40and the pocket support surface36.

It should be understood that throughout the description and claims of the present invention, the term “actuating” describes the act of initiating movement of the locking member52in a predetermined direction or along a predetermined path.

It should be also understood that throughout the description and claims of the present invention, the rearward direction R is generally opposite to the forward direction F.

The recess depth D1of the shaft recess62being greater than a third of the minimum shaft width WSMIN, provides an advantageously long path length for the locking member52to operatively engage with the abutment surface54, which allows selection of the optimum abutment angle α to transform the locking member52movement into the clamping force f applied between the second insert surface40and the pocket support surface36.

According to the present invention, the shaft axis A1does not intersect the pocket support surface36.

In some embodiments of the present invention, the clamping axis A2may also not intersect the pocket support surface36.

Also, in some embodiments of the present invention, the clamping member44may not make contact with the cutting insert24.

As shown inFIG. 3, the insert receiving pocket32may include a pocket clamping surface68opposing the pocket support surface36, with the pocket clamping surface68and the pocket support surface36being spaced apart by a clamping distance D2.

In some embodiments of the present invention, the locking member52may operatively engage the clamping shaft's abutment surface54to urge the pocket clamping surface68towards the pocket support surface36and clampingly retain the cutting insert24in the insert receiving pocket32by way of the clamping force f.

Also, in some embodiments of the present invention, the locking member52may have a central axis A5, and the clamping distance D2may be decreased by rotation of the locking member52in one direction about its central axis A5and increased by rotation of the locking member52in an opposite direction about its central axis A5.

Further, in some embodiments of the present invention, as shown inFIGS. 5 and 6, the central axis A5of the locking member52may be coaxial with the locking axis A3of the locking bore58.

As shown inFIG. 9, the locking member52may be in the form of a locking screw70having a threaded section72and a non-threaded section74.

In some embodiments of the present invention, as shown inFIGS. 6 and 9, the non-threaded section74may include an abutting surface76having a generally frusto-conical shape, and a portion of the abutting surface76may contact the abutment surface54of the clamping shaft46.

The abutting surface76having a generally frusto-conical shape, and the abutment surface54forming a portion of the frusto-conical shaped shaft recess62, results in operative engagement between the abutting surface76and the abutment surface54being ‘centralized’ towards an imaginary line of contact L1of the shaft recess62, which beneficially contributes to the high level of clamping repeatability.

As shown inFIGS. 10 to 12, the imaginary line of contact L1may be contained in a contact plane P4perpendicular to the shaft plane P1.

In some embodiments of the present invention, the abutting surface76may be outwardly convex in a side view of the locking screw70, which results in an optimally short length of contact along the imaginary line of contact L1.

As shown inFIG. 2, the pocket clamping surface68may be formed on an elongated clamping portion78of the holder head28, and the elongated clamping portion78may have a resilience axis of rotation A6rearward of the insert receiving pocket32, with the cutting insert24being actively clamped between the pocket clamping surface68and the pocket support surface36.

It should be understood that throughout the description and claims of the present invention, the term “actively clamped” denotes the application of the clamping force f which has to overcome the ‘resilience’ of the elongated clamping portion78and displace the elongated clamping portion78about its resilience axis of rotation A6before clamping of the cutting insert24can occur.

In some embodiments of the present invention, as shown inFIGS. 3 and 4, the coolant duct80may extend through the clamping portion78and open out to a coolant outlet port82adjacent the pocket clamping surface68, thus enabling coolant to be directed to the operative cutting edge42of the cutting insert24.

Also, in some embodiments of the present invention, the clamping head64may be countersunk in a clamping recess84of the elongated clamping portion78, such that for clamping head's64not exhibiting 180° rotational symmetry about the shaft axis A1, the clamping member44is limited to a single assembly position within the holder head28.

The clamping member44being limited to a single assembly position within the holder head28beneficially contributes to the high level of clamping repeatability.

As shown inFIGS. 3 and 4, the head under surface66may engage the elongated clamping portion68at a single clamping zone86of the clamping recess84located entirely forward of the clamping axis A2.

The single clamping zone86being located on only a portion of the clamping recess84, beneficially contributes to the high level of clamping repeatability.

The single clamping zone86being located entirely forward of the clamping axis A2, provides optimal transmission of the clamping force f through the elongated clamping portion78.

In some embodiments of the present invention, as shown inFIGS. 1 and 2, the cutting insert24may be blade shaped, and suitable for grooving, turning and parting operations.