Cutting tool comprising a cutting tool holder and a cutting insert therefor

Abstract

A cutting tool holder (110) configured for mounting thereon a cutting insert (140). The cutting tool holder comprises a body (112) formed with an insert seat (120) configured receiving therein the cutting insert and a seat bore (135) configured for accommodating therein a fastening member (150). The cutting tool holder also comprises an anchoring element (170) received within the body of the holder, the fastening element being configured for secured engagement with the anchoring element and being free of such engagement with the seat bore.

Claims

1. A cutting tool holder configured for mounting thereon a cutting insert, said cutting tool holder comprising: a body formed with an insert seat configured for receiving therein the cutting insert and comprising a side wall; and a seat bore comprising a corresponding support portion of the seat bore, located opposite the side wall of the seat, the seat bore configured for accommodating therein a fastening member including a head portion configured for abutting the support portion; wherein said cutting tool holder includes an anchoring element received within the body of the holder, said fastening member being configured for secured engagement with said anchoring element and being free of such engagement with the seat bore, the fastening member being configured for axial displacement along the seat bore and with respect to the anchoring element.

2. The cutting tool holder according to claim 1, further comprising: wherein the body includes a base surface; wherein the seat bore extends within the body along a bore axis, and having an open end at said base surface; an anchoring bore extends within the body along an anchoring axis oriented transverse to said bore axis, and intersecting with said seat bore to have a mutual intersection zone; a securing arrangement including: the fastening member having a proximal end and a distal end and configured for being received within the seat bore in a disengaged manner, said distal end being configured for securing the cutting insert into said insert seat; the anchoring element received within said anchoring bore and configured for being articulated to the proximal end of said fastening member at the mutual intersection zone, when the latter is received within said seat bore; wherein articulation between the fastening member and the anchoring element allows the fastening member to freely displace within said seat bore into a secured state in which the distal end secures said cutting insert into the insert seat.

3. The cutting tool holder according to claim 2, wherein the anchoring bore has at least one open end and a position and/or an orientation of the anchoring element with respect to the anchoring bore can be adjusted via said open end using a designated tool.

4. The cutting tool holder according to claim 2, wherein the distal end of the fastening member includes a head portion configured for engaging a designated portion of the cutting insert, a designated portion of the cutting tool holder or both to provide proper securing of the cutting insert into the insert seat in the secured state.

5. The cutting tool holder according to claim 2, wherein: displacement of the fastening member within the seat bore is axial; and the anchoring element is configured for maintaining a substantially fixed orientation within the anchoring bore during displacement of the fastening member.

6. The cutting tool holder according to claim 2, wherein the fastening member is configured for displacing with respect to the seat bore between a mounting state in which the distal end of the fastening member protrudes from the base surface to a first axial extent and is disposed at a first gap distance from the side wall, and a secured state in which said distal end protrudes from said base surface to a second axial extent, different than the first axial extent and is disposed at a second gap distance from the side wall, smaller than the first gap distance, so as to engage the cutting insert, thereby securing a portion thereof between a head portion of the fastening member and the side wall.

7. The cutting tool holder according to claim 6, wherein axial displacement of the fastening member between the mounting state and the secured state entails a respective displacement of the anchoring element, so that in the mounting state said anchoring element is in a first anchoring position with respect to said anchoring bore, and in said secured state, said anchoring element is in a second anchoring position with respect to said anchoring bore, different than the first anchoring position.

8. The cutting tool holder according to claim 6, wherein in the mounting state the first gap distance is such that allows said cutting insert to be placed onto the seat and/or being fully removed from the seat over the head portion of the fastening member.

9. The cutting tool holder according to claim 1, wherein the anchoring element is separate and detachable from the body of the cutting tool holder.

10. The cutting tool holder according to claim 1, wherein the fastening member includes a body that is configured for freely displacing within said seat bore without engaging the seat bore.

11. The cutting tool holder according to claim 1, wherein the fastening member is received within the seat bore in a loosely displaceable manner, thereby allowing lateral displacement thereof with respect to the seat bore in a direction transverse to a bore axis of the seat bore.

12. The cutting tool holder according to claim 1, wherein the fastening member is configured for assuming a mounting state within said seat bore in which a cutting insert can be placed in the insert seat, and a secured state in which the cutting insert is secured within the seat.

13. The cutting tool holder according to claim 1, wherein the fastening member is configured to be displaced within the seat bore either laterally or pivotally.

14. The cutting tool holder according to claim 13, wherein: the fastening member includes a head portion that is asymmetrically shaped around an axis of the fastening member; and the support portion is adjacent said head portion.

15. The cutting tool holder according to claim 14, wherein revolution of the fastening member about an axis thereof entails lateral displacement of the head portion of the fastening member towards the side wall as a result of its engagement with the support portion.

16. The cutting tool holder according to claim 14, further comprising an anchoring bore extending within the body along an anchoring axis oriented transverse to a bore axis of the seat bore, the anchoring bore intersecting with said seat bore to have a mutual intersection zone, the anchoring bore oriented transverse to both the seat bore and a movement direction of the head portion of the fastening member, whereby displacement of the head portion towards the side wall entails revolution of the anchoring element within the anchoring bore about the anchoring bore's axis.

17. The cutting tool holder according to claim 14, further comprising an anchoring bore extending within the body along an anchoring axis oriented transverse to a bore axis of the seat bore, the anchoring bore intersecting with said seat bore to have a mutual intersection zone, the anchoring bore is oriented transverse to the seat bore and along a movement direction of the head portion of the fastening member, whereby displacement of the head portion towards the side wall entails axial displacement of the anchoring element within the anchoring bore along the anchoring axis.

18. The cutting tool holder according to claim 1, wherein the anchoring bore is oriented transverse to the seat bore and along a movement direction of the head portion of the fastening member, whereby displacement of the head portion towards the side wall entails axial displacement of the anchoring element within the anchoring bore along the anchoring bore's axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

(2) FIG. 1A is a schematic cross-sectional view of a cutting tool according to one example of the present application, show in a mounting state thereof;

(3) FIG. 1B is a schematic cross-sectional view of a cutting tool according to one example of the present application, show in a secured state thereof;

(4) FIG. 2A is a schematic isometric view of a cutting tool according to another example of the present application;

(5) FIG. 2B is a schematic exploded isometric view of the cutting tool shown in FIG. 2A;

(6) FIG. 2C is a exploded isometric view of the cutting tool holder shown in FIG. 2B;

(7) FIGS. 3A to 3C are schematic cross-sectional views of the cutting tool shown in FIGS. 2A and 2B, shown during consecutive stages between a mounting state and a secured state;

(8) FIGS. 3D to 3F are respective schematic enlarged view of a portion of the cutting tool shown in FIGS. 3A to 3C;

(9) FIGS. 4A to 4C are schematic cross-sectional views of the cutting tool shown in FIGS. 2A and 2B, shown during consecutive stages between a mounting state and a secured state, also demonstrating displacement of the cutting insert thereof;

(10) FIGS. 5A to 5C, are schematic partial top views of the consecutive stages shown in FIGS. 4A to 4C;

(11) FIG. 6A is a schematic isometric view of a cutting tool according to another example of the present application;

(12) FIG. 6B is a schematic exploded isometric view of the cutting tool shown in FIG. 6A;

(13) FIGS. 7A to 7D are respective schematic isometric, top, cross-section and enlarged views of a cutting insert used in the cutting tool shown in FIGS. 6A and 6B;

(14) FIGS. 8A and 8B are schematic cross-section views of another example of a cutting tool of the present application incorporating the cutting insert shown in FIGS. 7A to 7D, shown during a mounting state and a secured state respectively;

(15) FIGS. 8C and 8D are schematic partial top views of the cutting tool shown in FIGS. 8A and 8B;

(16) FIG. 9A is a schematic isometric view of a cutting tool according to another example of the present application;

(17) FIG. 9B is a schematic exploded isometric view of the cutting tool shown in FIG. 9A;

(18) FIGS. 10A and 10B are schematic cross-section views of another example of a cutting tool of the present application, shown during a mounting state and a secured state respectively;

(19) FIGS. 10C and 10D are respective schematic enlarged view of a portion of the cutting tool shown in FIGS. 10A and 10B; and

(20) FIGS. 11A and 11B are schematic isometric and front cross-section views of a cutting insert used in the cutting tool shown in FIGS. 9A to 10D.

DETAILED DESCRIPTION OF EMBODIMENTS

(21) Attention is first drawn to FIGS. 1A and 1B, in which a cutting tool is shown, generally designated as 1 and comprising a cutting tool holder 10 and a cutting insert 40 mounted thereon using a securing arrangement comprising a fastening member 50 and an anchoring element 70. In all the following figures, where shown in cross-section, the cutting tool holder 10 is shown unhatched.

(22) The cutting tool holder 10 comprises a body 12 formed with an insert seat 20 defined by a base surface 22 and two side surfaces 24 (not shown), forming a corner with a relief bore 16. The insert seat 20 further comprises a seat bore 25 having at open end at the base surface 22, and configured for accommodating therein the fastening member 50.

(23) The cutting insert 40 is respectively formed with an insert bore 45 configured for receiving therethrough the fastening member 50.

(24) The fastening member 50 is in the form of a screw and comprises a shank 52 extending between a proximal end P.E. received within the seat bore 25 and a distal end D.E. projecting from the seat bore 25 and formed with a head portion. The head portion comprises a fastening surface 54 which is inclined with respect to an axis of the fastening member and configured for coming into contact with a respective portion of the cutting insert, at least in the secured state.

(25) The fastening member 50 has also a threaded portion 56 beginning at its proximal end P.E. and configured for engaging and articulating with the anchoring element 70.

(26) The cutting tool holder also comprises an anchoring bore oriented transverse to the seat bore 20 (shown here in its round cross-section), which is configured for accommodating therein an anchoring element 70. The anchoring element comprises a body 72 and a threaded bore 76, configured for engagement and articulation with a proximal end of the fastening member.

(27) As shown in FIG. 1A, the proximal end P.E. of the fastening member 50 is threaded into the anchoring element to a first extent, such that the majority .sub.1 of the threaded bore 76 is free of the fastening member 50. In this position, the head portion of the fastening member 50 is not in contact with the cutting insert 40 and so the latter is just loosely positioned within the seat 20.

(28) Turning now to FIG. 1B, when the fastening member is screwed in, it displaces downwards to the position shown in FIG. 1B. In this position, most of the proximal end P.E. of the fastening member 50 is threaded into the anchoring element (to a second extent, greater than the first), such that only a minority .sub.2 of the threaded bore 76 is free of the fastening member 50. In this position, the head portion of the fastening member 50 abuts the cutting insert 40 and presses it downwards toward the base surface 22, holding it in place in the secured state.

(29) It is appreciated that in the present example, the purpose of the anchoring element 70 is to replace the thread of the insert bore 25 as common in cutting tool holders. In addition, since the fastening member only performs an axial movement during its displacement between the mounting state and the secured state, and since the head portion performs no lateral movement, no forces are transferred to the anchoring element 70, which remains in essentially the same position and orientation during both states.

(30) Turning now to FIGS. 2A to 2C, another example of a cutting tool is shown, generally designated 101, and comprising a cutting tool holder 110 having an insert seat 120 with a base plate 190 thereon, and a cutting insert 140 mounted onto the base plate of the seat 120 using a securing arrangement (150, 170) comprising a fastening member 150 and an anchoring element 170.

(31) As observed, the insert seat 120 is formed with a support structure 130 projecting above the base surface 122 and the corresponding seat bore 125 formed in the seat 120 (and having an open end at the base surface 122). The support structure 130 comprises a hollow body 132 extending from the base surface 122 and having an inner cavity 135, and which is formed with an extension 134 having an inclined support surface 136 on the inner side of the cavity 135.

(32) In addition, the anchoring element 170 is accommodated within an anchoring bore 114 extending transverse to the seat bore 125, and having two open ends 115a, 115b. The anchoring element 170 also comprises a body 172 formed with a threaded anchoring bore 176 and an access port 178 at one end thereof, which is accessible (in the shown example) via one of the openings 115b.

(33) Turning now to FIGS. 3A and 3D, the fastening member 150 comprises a head portion 152 formed with an access port 159 configured for receiving therein a designated tool for operating the fastening member 150. The head portion 152 comprises a fastening surface 154 which is inclined with respect to the axis X.sub.S of the fastening member 150 an configured for abutting a designated portion of the cutting insert 140 at least in the secured position, and an abutment surface 155, also inclined with respect to the axis X.sub.M of the fastening member 150 and configured for abutting a corresponding support surface 136 of the support structure 130.

(34) In assembly, the fastening member 150 is received within the seat bore 125 and the threaded portion 158 at the proximal end thereof is threadingly engaged with the corresponding threaded bore 176 of the anchoring element 170. The proximal end is threaded to an extent .sub.1 over the center of the cross-section of the anchoring element 170.

(35) It is observed, in this position, that the diameter d of the fastening member is smaller than the diameter D of the seat bore 125. Specifically, the side of the shank 152 is flush against the left portion of the inner surface of the seat bore 125 (a minimal distance e.sub.1), leaving a space between the inner surface of the seat bore 125 and the shank 152 of the fastening member 150 (to the right of the fastening member). This space, as will be explained in detail with respect to FIGS. 3B to 3F, is essential in providing the fastening member 150 with a space to displace in.

(36) Further in assembly, the base plate 190 is mounted over the portion 132 of the support structure so as to rest on the base surface 122 of the insert seat 120. It is noted that the hole in the base plate 190 fits in size and dimension to those of the portion 132.

(37) On top of the base plate 190, the cutting insert 140 is placed. In this connection, the head portion 152 of the fastening member 150 is designed such that the nominal dimension of its largest cross-section is still smaller than that of the insert bore 145, allowing the placement of the cutting insert 140 onto the base plate 190, even when the fastening member 150 is already positioned within the seat bore 125. Specifically, in the position shown in FIG. 3A, the cutting insert 140 is not only placed onto the base plate 190, but is also already placed to assume a location which is essentially similar to the location of the insert 140 in the secured position (although, as shown in FIG. 3A, the cutting insert 140 is not yet secured).

(38) In the position shown in FIGS. 3A and 3D, the insert bore 145 of the cutting insert is configured for accommodating therethrough not only a portion of the fastening member 150, but also for accommodating therein the extension 134 of the support structure 130. It is observed that when mounted onto the extension 134 of the support structure 130, the inner surface of the insert bore 145 does not abut the outer surface of the extension 134, leaving a slight gap g. The importance of the gap will be discussed in detail with respect to FIGS. 3B to 3F.

(39) In operation, starting from the mounting state shown in FIGS. 3A and 3D (or FIG. 4Athe mounting state is a definition based on the position of the fastening member 150, not on that of the cutting insert 140), the fastening member 150 can be revolved (using a designated tool such as a screw-driver) within the seat bore 125. Such revolution, owing to the thread engagement between the fastening member 150 and the anchoring member 170, entails downward axial displacement of the fastening member 150.

(40) Owing to the abutment between the abutment surface 155 and the support surface 136, such downward axial displacement urges the head portion 152 of the fastening member 150 to the right, i.e. towards the side wall of the insert seat 120. However, since the anchoring bore 114 is oriented both transverse to the seat bore 125 and to the direction of this rightward movement of the head portion 152, the anchoring element 170 is urged to perform a rotational movement about its own axis. As a result, the fastening member 150 performs, in addition to its axial downward movement, a pivotal movement with a pivot point at the center of the cross-section of the anchoring element 170, bringing the head portion 152 closer to the side wall 124 of the insert seat 120.

(41) Thus, following such displacement, the position shown in FIGS. 3B and 3E is reached. In this position, it is observed that the fastening member 150 has descended so that the proximal end is threaded to an extent .sub.2>.sub.1 over the center of the cross-section of the anchoring element 170. Additionally, the axis X.sub.S of the fastening member 150 is now tilted at an angle .sub.1 with respect to the axis X.sub.M of the seat bore 125 (contrary to the previously shown position in which they were parallel.sub.0), leaving a spacing e.sub.2>e.sub.1 between the left portion of the inner surface of the seat bore 125. Furthermore, due to the combined downward and pivotal movement performed by the fastening member 150, the fastening surface 154 displaces closer to the corresponding chamfer portion 148 of the cutting insert 140.

(42) Upon further revolution of the fastening member 150 about its central axis X.sub.S, it further displaces downwards, simultaneously with performing its pivot movement until reaching the position shown in FIGS. 3C and 3F.

(43) In this position, it is observed that the fastening member 150 has descended so that the proximal end is threaded to an extent .sub.2>.sub.1 over the center of the cross-section of the anchoring element 170. Additionally, the axis X.sub.S of the fastening member 150 is now tilted at an angle .sub.2>.sub.1 with respect to the axis X.sub.M of the seat bore 125, leaving a spacing e.sub.3>e.sub.2 between the left portion of the inner surface of the seat bore 125. Furthermore, due to the combined downward and pivotal movement performed by the fastening member 150, the fastening surface 154 now abuts the corresponding chamfer portion 148 of the cutting insert 140, to firmly hold the cutting insert 140 in place.

(44) In this secured state shown in FIGS. 3C and 3F, the head portion 152 both presses down on the cutting insert 140 due to its abutment with the chamfer surface 148, and also presses the cutting insert 140 laterally towards the side wall 124. In this position, the distance between the head portion 152 and the side wall 124 is smaller than the dimension of the portion of the cutting insert 140 held therebetween, thus preventing removal of the cutting insert 140 from the cutting tool holder 110.

(45) It is noted that in the secured state, the walls of the cutting insert 140 abut and are pressed against the side walls 124 of the insert seat 120 (see FIG. 5C), still maintaining the gap g between the inner surface of the hole 145 of the cutting insert 140 and the extension 134.

(46) Turning now to FIGS. 4A to 5C, another sequence of mounting and securing the cutting insert 140 is shown, in which, contrary to the sequence shown in FIGS. 3A to 3F, the cutting insert 140 is gradually pushed into place by the fastening member 150.

(47) In particular, in the position shown in FIGS. 4A and 5A, the cutting insert 140 is mounted over the head portion 152 of the fastening member 150 to be placed flush onto the base plate 190, but its lateral position is not the same as in its secured state (FIG. 4C). Specifically, the chamfer portion 148 of the cutting insert 140 abuts the outer surface 153 of the head portion 152 of the fastening member 150, the distance between the cutting insert 140 and the side wall is .sub.1 and the distance between the cutting insert 140 and the corner 116 of the insert seat 120 is L.sub.1.

(48) Upon downward displacement of the fastening member 150 into the seat bore 125, owing to the above abutment with surface 153, the pivotal movement of the head portion 152 pushes the cutting insert 140 towards the corner 116, to the position shown in FIG. 4B. In this position, the distance between the cutting insert 140 and the side wall is .sub.2<.sub.1 and the distance between the cutting insert 140 and the corner 116 of the insert seat 120 is L.sub.2<L.sub.1.

(49) Further screwing of the fastening member 150 and consequent downwards movement thereof entails further pushing of the cutting insert 140 to the position shown in FIG. 4C, which is essentially similar to that shown in FIGS. 3C and 3F. In this position, the fastening surface 154 firmly abuts the chamfer portion 148, the distance between the cutting insert 140 and the side wall is .sub.3<.sub.2 and the distance between the cutting insert 140 and the corner 116 of the insert seat 120 is L3<L2.

(50) Attention is now drawn to FIGS. 6A and 6B, in which yet another cutting tool is shown, generally designated as 101, and comprising a cutting tool holder 110 having an insert seat 120 with a base plate 190 thereon, and a cutting insert 140 mounted onto the base plate of the seat 120 using a securing arrangement comprising a fastening member 150 and an anchoring element 170.

(51) Turning now to FIGS. 7A to 7D, the cutting insert 140 comprises a body defined by a top face 141T, a bottom face 141B and side walls 141S extending therebetween. The cutting insert 140 is reversible, and is thus symmetrical about a plane (not shown) extending parallel to the top/bottom face and located therebetween. Only one half of the cutting insert 140 will now be described, noting that the opposite half is completely symmetrical.

(52) The cutting insert comprises an insert bore 145 constituted by several designated surfaces: a chamfer surface 148, extending from the top face 141T, four intermediate surfaces 147 extending from the chamfer surface 148 parallel to the axis of the insert bore 145, four abutment surfaces 149 each extending from a respective intermediate surface 147 and oriented at an angle to the axis of the insert bore 145, and a central surface C extending from the respective abutments surfaces 149 parallel to the axis of the insert bore 145, and across the symmetry plane.

(53) It is noted that each of the four abutment surfaces 149 has a smaller curvature radius than that of the chamfer surface 148, whereby together they form a flower-type opening rather than a completely circular one (as of the chamfer surface 148).

(54) Specifically, each of the abutment surfaces 149 is constituted by a conical surface extending between a narrow edge 149.sub.N with a first radius of curvature r and a wide edge 149.sub.W, with a second radius of curvature R>r. The arrangement is such that the narrow edges 149.sub.N of the abutment surfaces 149 form together a complete circular contour. In contrast, the second radius of curvature R is smaller than the radius of curvature R of the inscribing circle (not shown) of the wide edges 149W of the abutment surfaces 149, so that the centers of curvature of the wide edges 149.sub.W do not coincide with the center O of the cutting insert 140. As a result, the wide edges 149.sub.W form together a flower-like contour rather than a circular one (see FIG. 7B). This arrangement provides for better abutment with the fastening member 150 as will be explained in detail with respect to FIGS. 8A to 8D.

(55) A similar arrangement is provided for the intermediate surfaces 147, whereas the central surface C (at least in this particular example) is completely circular, similar to the chamfer surface 148.

(56) The cavity 145 of the cutting insert 140 is such that the cutting insert 140 can be easily manufactured in a pressing process, in the sense that it does not comprise undercuts or geometry which would make it difficult to manufacture in such a process.

(57) With additional reference being made to FIGS. 8A to 8D, a cutting tool is shown, generally designated 101, and comprising a cutting tool holder 110 with a support structure 130, a base plate 190, and the cutting insert 140 mounted thereon using a securing arrangement comprising a fastening member 150 and the anchoring element 170 as used in the previous example.

(58) The fastening member 150 is of a similar design to fastening member 150, albeit slightly differing complementary to the design of the inner surface of the insert bore 145. The fastening member 150 comprises a head portion 152 with an access port 159, and is formed with a fastening surface 154 extending below the head portion 152 thereof and configured for abutting the cutting insert 140, and an abutment surface 155 configured for coming into contact with an abutment surface 136 of the support structure 130.

(59) In assembly, the base plate 190 is mounted over the base 132 of the support structure 130, leaving an extension 134 protruding from the base plate 190. The fastening member 150 is received within the seat bore 125 and has its proximal end articulated to the anchoring element 170 (not shownarticulation is similar to that described with respect to FIGS. 2A to 5C). The cutting insert 140 is mounted over the head portion 152 of the fastening member 150, such that the insert bore 145 thereof receives therein the extension 134, the chamfer surface 148 residing over it at a gap distance g.

(60) In the position shown in FIG. 8A, the cutting insert 140 is not in its secured position and the central surface C thereof abuts the head portion 152 of the fastening member 150. The cutting insert 140 is spaced at a distance l.sub.1 from the corner 116 of the cutting tool holder 110, and at a distance .sub.1 from the side walls 124 of the insert seat 120.

(61) With further reference being made to FIGS. 8C and 8D, upon rotation of the fastening member about its axis, as previously described with respect to FIGS. 2A to 5C, the fastening member performs a downward displacement wherein the abutment between the surface 155 thereof and the support surface 136 causes a pivotal motion of the fastening member 150 about the center of the anchoring element's cross-section.

(62) Upon sufficient such displacement, the fastening surface 154 to be urged closer towards a respective of the four abutment surfaces 149 of the cutting insert 140 to properly clamp it against both the side wall 124 and the base plate 190, as shown in FIG. 8B. In this position, the distance between the cutting insert 140 and the corner 116 is now l.sub.2<l.sub.1, and the walls of the cutting insert 140 are flat against the side walls 124 of the insert seat 120, i.e. .sub.2=0<.sub.1.

(63) In addition, it is noted that, as in previous examples, conical dimensions of the fastening surface 154 of the fastening member 150 is smaller than that of the bore 145 of the cutting insert 140, i.e. the fastening member has, in a cross-section perpendicular to the axis of the insert bore 145, a smaller radius of curvature r than that of the respective inscribing circle of the insert bore 145 at that cross-section. However, reverting back to FIGS. 7A to 7D, since the abutment surfaces 149 also have a radius of curvature r smaller than that of the inscribing circle of the bore 145, this yields a surface-to-surface match between the fastening surface 154 and the respective of the abutment surfaces 149 of the cutting insert 140 with which it comes into contact.

(64) It is important to note that were the abutment surfaces 149 of the cutting insert 140 of a larger radius of curvature than that of the fastening surface 154, it would yield a point-to-point contact between the latter and the former, rather than a surface-to-surface contact. The given configuration of the abutment surfaces 149 provides a more secure and firm engagement of the surfaces 154, 149, at a location of the insert bore 145 opposite the working corner 142 of the cutting insert 140.

(65) The sequence shown here is similar, in essence, to that described with respect to FIGS. 4A to 5C, in which displacement of the fastening member is the one responsible for bringing the cutting insert 140 to its proper secured position.

(66) It is also appreciated that in the described example of FIGS. 8A to 8D, the cavity 145 of the cutting insert 140 is larger at the ends thereof so as to be wide enough to accommodate the extension 134 of the support structure 130 therein, whereas the inner diameter of the cavity 145 is smaller, in order to properly interact with the head portion 152 of the fastening member.

(67) Attention is now drawn to FIGS. 9A and 9B, in which yet another example of a cutting tool is shown, generally designated as 201. The cutting tool 201 comprises a cutting tool holder 210 which has an insert seat 220 formed with a support structure 230, a base plate 290, a cutting inset 240 mounted onto the cutting tool holder 210 and secured in place by a securing arrangement comprising a fastening member 250 and a spring biased anchoring element 270.

(68) Contrary to the previously described examples, in the present example the anchoring bore 214 extends transverse to the axis of the seat bore 225 but along the direction of movement of the fastening member 250, i.e. extending towards the corner 216 of the insert seat 220.

(69) With additional reference being made to FIG. 10A, in assembly, the base plate 290 is mounted over the base 232 of the support structure 230, and the fastening member 250 is received within the insert bore 225, with its proximal end threaded into the anchoring element 270, and the distal end thereof projecting from the base place 290. The dimension D of the bore 225 is greater than the diameter d of the shank 256 of the fastening member 250, allowing it sufficient displacement space. The cutting insert 240 is mounted over the head 252 of the fastening member 250, and is shown in its mounting position, spaced at a distance L1 from the corner 216.

(70) Upon revolution of the fastening member 250, it performs a downward axial movement owing to is screwing engagement with the anchoring element 270. During this movement, owing to the abutment between the abutment surface 254 and the support surface 236, the downward displacement urges the head portion 252 to displace rightward towards the corner 216 of the cutting tool holder 210.

(71) Contrary to the previous examples shown in FIGS. 2A to 8D, in the present example, owing to the orientation of the anchoring bore 214, such rightward lateral displacement of the head portion 252 entails axial displacement of the anchoring element 270 in the same direction (contrary to a rotary movement as in the previous examples).

(72) Thus, with additional reference to FIGS. 10B to 10C, upon such downward displacement of the fastening member 250 and simultaneous rightward traveling thereof, the anchoring element 270 also displaces to the position shown in FIGS. 10B and 10D.

(73) In the position shown in FIGS. 10B and 10D: the cutting insert 240 is spaced a distance L2<L1 from the corner 216; the proximal end of the fastening member is threaded to an extent .sub.2>.sub.1 over the center of the cross-section of the anchoring element;

(74) the fastening member 250 is spaced a distance e.sub.2>e.sub.1 from the left side portion of the inner surface of the seat bore 225; and the anchoring element 270 is spaced a distance l.sub.2<l.sub.1 from the closed end of the anchoring bore 214.

(75) It is appreciated that in the given example, the insert bore 245 of the cutting insert 240 does not accommodate therein any portion of the support structure 230. It is also appreciated that the fastening member 250 comprises a surface 254 which serves both as the abutment surface which is mated against the support surface 236 of the support structure 230 and as the fastening surface abutting the cutting insert 240.

(76) In the present example, the spring 278 is configured for returning the anchoring 270 element back to its original position when the cutting insert 240 is removed from the cutting tool holder 210.

(77) Finally, attention is drawn to FIGS. 11A and 11B, in which the cutting insert 240 is shown in detail. The cutting insert had a top face 241T and a bottom face 241B, and the insert bore 245 is formed with a plurality of abutment surfaces 248. Each of the abutment surfaces 248 is constituted by a conical surface tapering outwards towards the top face 241T, and has a narrow edge 248.sub.N and a wide edge 248.sub.W.

(78) It is observed that the abutment surface 248 is disposed much closer to the bottom face 241B of the cutting insert 240 than to the top face 241T. More specifically, it is noted that the wide edge 248.sub.W of the abutment surface 248 is disposed between the narrow edge 248.sub.N and the top surface 241T, and is also much closer to the bottom face 241B than to the top face 241T. This is opposed to standard cutting inserts in which the conical surface configured for coming into contact with the fastening screw is constituted by a chamfer surface of the cutting insert and is usually disposed closer to the top face of the cutting insert.

(79) The above arrangement allows the fastening surface 254 of the fastening member 250 to secure the cutting insert 240 into place at a much lower location, i.e. at a portion of the cutting insert 240 which is closer to the base surface 222. This, in turn, provides for a more robust securing of the cutting insert 240 into the insert seat 220.

(80) In particular, since the fastening of the cutting insert 240 is performed via an abutment surface 248 which is associated with a bottom face 241B of the cutting insert 240, this also yields that the head portion of the fastening member 250 minimally protrudes into the insert seat 220 from the insert bore 225. Thus, a smaller (shorter) portion of the fastening member 250 extends outside the seat bore 225, thereby reducing the fastening member's 250 susceptibility to bending forces which may take place during fastening.

(81) Those skilled in the art to which this invention pertains will readily appreciate that numerous changes, variations, and modifications can be made without departing from the scope of the invention, mutatis mutandis.