Patent Description:
<CIT> discloses a parting off device for rotating workpieces comprising an adaptor rotatably connected to a tool holder and comprising an insert in a pocket of the adaptor. As shown in <FIG>, the insert pockets are positioned at diametrically opposed sides of the adaptor. This is done to maximize cutting depth, since the cutting edges of the inserts are wider than the adaptor, and to have them positioned closer to each other would reduce the cutting depth capability.

As understood by <FIG>, the non-rotating tool is configured for the inserts to be used successively as opposed to concurrently. To elaborate, after an operative edge is, for example, worn, a successive edge can be selected to become an operative edge. This can be achieved by one of two ways, namely by replacing the worn insert in the pocket with a new insert or rotating (indexing) the adaptor so that a different insert in a different pocket is presented as a new operative edge.

It will be understood that the present application is directed only to adaptors of the type being configured for rotation (indexing) about a central index axis (hereinafter called adaptor index axis) which positions a different insert to be the active insert for a parting off application. Stated differently it relates to insert adaptors which position a single insert in an operational position and after use thereof position a different single insert in the operational position (i.e. successive insert use).

For such parting operations to work, a workpiece is rotated and the adaptor is moved in an operational direction into the workpiece. The operational direction is typically parallel, or substantially parallel, with an elongation direction of a tool holder's elongated shank.

It is an object of the present application to provide a new and improved insert adaptor and tool assembly comprising same.

In accordance with the invention of the present application, there is provided an insert adaptor for parting off having an adaptor index axis according to independent claim <NUM>.

Previously, only two pockets were known for such adaptors. Increasing the number of pockets around a peripheral surface of an insert adaptor was previously thought disadvantageous for reducing cutting depth compared to known adaptors with two diametrically opposed pockets (due to the limitation caused during usage by the cutting edge width of an insert inside the pocket), and will increase adaptor production costs due to manufacturing of additional pocket(s), it is believed that such disadvantages can be offset by an increased pocket life which thereby increases the overall lifetime of the adaptor.

Yet a further, separate advantage, is that even though production of an insert with three or more cutting edges circumferentially spaced therearound may be simpler than a separate adaptor and insert manufacturing construction (requiring production of the pockets etc.) it has been found that comparatively long cemented carbide inserts require a greater width than metal, particularly steel, thereby increasing the material wastage in parting off operations which require relatively deep cuts. While the cemented carbide is structurally stronger, nonetheless a slightly thinner adaptor can be achieved with metal than cemented carbide, which for certain operations can be advantageous.

It has further been found that when using such insert adaptor with only a single insert only, the previously considered disadvantageous effect of reduced cut length can be eliminated.

In accordance with the subject matter of the present application, the adaptor peripheral surface may be formed with exactly five pockets.

Even though five pockets along an adaptor peripheral surface even further reduces the possible cutting depth, relative to a smaller number of pockets (understanding that for parting off assemblies cutting edges extend wider than the adjacent adaptor portion), nonetheless such number of pockets is believed to be the optimal number for number of cutting edges while still providing chip evacuation space for most applications. Even though it is preferred for all embodiments that pockets are configured to resiliently hold cutting inserts therein, the advantages of a five pocket insert adaptor are believed to even be advantageous in this particular case for inserts (made of a harder material than the insert adaptor itself, e.g. being made of cemented carbide and the insert adaptor being made of steel) which are permanently attached to the insert adaptor (e.g. by brazing). However, as with all ongoing developments, more than five pockets may be feasible, despite the reduced chip evacuation space, such embodiments, however, not falling within the scope of the current invention.

In accordance with the invention, there is provided an insert adaptor for parting off having an adaptor index axis and comprising: parallel adaptor first and second sides connected by an adaptor peripheral surface which extends peripherally around the adaptor; the adaptor index axis extending through the center of the first and second sides; wherein the adaptor peripheral surface is formed with bearing surfaces extending between the pockets.

It will be understood that while an insert adaptor could be formed with many geometric shapes, nonetheless, in particular for parting off applications (in which it is more economical to form as thin a slot as possible to reduce material wastage) it is believed that straight bearing surfaces provide the greatest structural strength for relatively extremely thin adaptors.

In accordance with the invention, there is provided an insert adaptor for parting off having an adaptor index axis and comprising: parallel adaptor first and second sides connected by an adaptor peripheral surface which extends peripherally around the adaptor; the adaptor index axis extending through the center of the first and second sides; wherein the adaptor peripheral surface is formed with the said pockets, each of the pockets optionally comprising an ejection gap at a rear end thereof.

It will be understood that all references to "inserts" in the present application prefer to components which are detachable from an insert adaptor and are not permanently connected thereto (e.g. by brazing).

A further aspect, although not falling within the scope of the current invention, would be the use of (or a method of machining) an insert adaptor according to the invention with only a single insert mounted in a pocket in an operational position and at least the adjacent pockets to said pocket being free of inserts.

There may be provided a tool holder comprising an elongated tool shank (<NUM>) and a tool head (<NUM>) extending from the tool shank (<NUM>) and configured for holding an insert adaptor according to the invention.

The tool holder is a non-rotating tool holder (i.e. not configured for rotation). Thus an adaptor recess can extend along a side of the tool holder, and need not be perpendicular to an elongated direction thereof as with rotating tools.

There may be provided a tool assembly comprising such a tool holder, an insert adaptor according to the invention, and one or more inserts mounted to the insert adaptor.

In accordance with the present application, the tool assembly would comprise a tool holder and an insert adaptor according to the invention and an insert mounted to one of the pockets of the insert adaptor; the insert comprising a cutting edge having a cutting edge thickness measured parallel with the adaptor index axis IA; the insert adaptor comprising an adaptor thickness measured parallel with the adaptor index axis IA, which is smaller than the cutting edge thickness; the insert adaptor being mounted to an adaptor recess of the tool holder.

A method of indexing the tool assembly, which does not fall within the scope of the invention, comprises the steps of loosening a screw holding an insert adaptor to a tool holder, rotating the insert adaptor until a different insert is located in an active cutting position and fastening the screw to thereby bring the insert adaptor to a secure mounted position.

It is understood that the above-said is a summary, and that the following features, either alone or in combination, may be applicable to the tool holder or tool assembly according to claims <NUM> and <NUM> respectively:.

For a better understanding of the subject matter of the present application, and to show how the same may be carried out in practice, reference will now be made to the accompanying drawings, in which:.

Reference is made to <FIG>, illustrating a tool assembly <NUM> configured for parting off operations.

The tool assembly <NUM> can comprise an insert adaptor <NUM>, an insert <NUM> (<FIG>; such insert designation may additionally or alternatively be designated with a suffix e.g., first, second, third, fourth and fifth pockets 14A, 14B, 14C, 14D, 14E; further designations below are also made in such manner) mounted to the insert adaptor <NUM>, a tool holder <NUM>, and a screw <NUM> used to secure the insert adaptor <NUM> to the tool holder <NUM>.

Referring now also to <FIG>, the insert adaptor <NUM> can comprise parallel adaptor first and second sides 20A, 20B connected by an adaptor peripheral surface <NUM>, and can have an adaptor index axis IA extending through the center of the adaptor first and second sides 20A, 20B.

The adaptor peripheral surface <NUM> is formed with pockets <NUM> (also suffixed, e.g., first, second, third, fourth and fifth pockets 24A, 24B, 24C, 24D, 24E). The pockets <NUM> can preferably be equally circumferentially spaced about the adaptor index axis IA.

Preferably, each of the pockets <NUM>, as shown in the present example, are identical, and, for the sake of succinctness only, a generic pocket designated "<NUM>" shown in <FIG> will be described in detail.

The pocket <NUM> can open out to a front end <NUM>, and can further comprise a rear end <NUM>, and opposing upper and lower clamp surfaces <NUM>, <NUM> extending between the front and rear ends <NUM>, <NUM>.

A clamping gap <NUM> can be defined between the upper and lower clamp surfaces <NUM>, <NUM>.

An ejection gap <NUM> can be defined between the clamping gap <NUM> and the rear end <NUM>, and in the present example the pocket <NUM> comprises a single concave end portion <NUM> at the rearmost end thereof.

In <FIG>, it is shown that both the upper and lower clamp surfaces <NUM>, <NUM> have a ridge shape, i.e. a convex shape each of which preferably have an apex 40A, 40B aligned with an adaptor plane PA (<FIG>) bisecting the first and second sides 20A, 20B. It will be understood that the opposite shape, i.e. a crest shape, is also one of other possibilities.

In the side view of <FIG>, it is shown that one of the clamp surfaces, in this example the upper clamp surface <NUM> is straight (stated differently, follows a linear path in a side view such as that shown). Whereas the other clamp surface, in this example the lower clamp surface <NUM> comprises two contact areas 42A, 42B separated by a relief recess 42C, for more secure mounting of the insert <NUM> (not shown in <FIG>).

The ejection gap <NUM> can also constitute a relief portion, by being further enlarged than the clamping gap <NUM>. More precisely, the enlargement referred to is that shown in a side view (<FIG>) in that a minimum first distance L<NUM> between, and perpendicular to, the upper and lower clamp surfaces <NUM>, <NUM> is smaller than a parallel minimum second distance L<NUM> of the ejection gap <NUM> to the first distance L<NUM>.

The pocket <NUM> can further be formed with an insert stopper surface <NUM>. In <FIG> the insert stopper surface <NUM> is located along the periphery of the insert adaptor <NUM> between the front end <NUM> and the upper clamp surface <NUM>. The insert stopper surface <NUM> is transverse, although not necessarily perpendicular to the upper clamp surface <NUM>. An intermediary surface <NUM> may or may not be present between the insert stopper surface <NUM> and a bearing surface <NUM> adjacent thereto (see for comparison, e.g. <FIG>).

In <FIG> an alternative insert stopper surface <NUM>' is exemplified as located at a rear end <NUM>' of a pocket <NUM>'. The insert stopper surface <NUM>' being essentially perpendicular to an elongation direction DE of the pocket <NUM>". However, as shown in <FIG>, even an insert stopper surface <NUM>" is located at a rear end <NUM>" of a pocket <NUM>" need not be perpendicular to an elongation direction DE of the pocket <NUM>" (in this case directed slightly downward along direction DD). To accommodate different insert shapes, a pocket <NUM>" may include an additional insert stopper surface <NUM>‴. In some embodiments, there may be two ejection or relief gaps <NUM>', <NUM>".

Reverting to <FIG>, to facilitate fastening of the insert adaptor <NUM> to the tool holder <NUM>, the insert adaptor <NUM> can be formed with a fastening configuration <NUM> in the center thereof. Preferably, the fastening configuration <NUM> is a single screw hole <NUM> opening out to the first and second sides 20A, 20B. The screw hole <NUM> can comprise a taper portion <NUM> tapering inwardly from the first and second sides 20A, 20B.

The adaptor peripheral surface <NUM> can be formed with a straight bearing surfaces <NUM> (also suffixed, e.g., first, second, third, fourth and fifth pockets bearing surfaces 52A, 52B, 52C, 52D, 52E), i.e. in a side view (e.g. <FIG>) extending between the pockets <NUM>. Preferably, the bearing surfaces <NUM> can also be planar. The bearing surfaces <NUM> are in the present example preferably arranged to form a basic pentagonal shape.

As noted above, the insert adaptor <NUM> can have a particularly solid construction excluding the insert pockets <NUM> and the screw hole <NUM>. To quantify an imaginary circle IC (<FIG>) can be extended to an imaginary cylinder with an insert adaptor thickness TA (<FIG>) which encompasses the insert adaptor <NUM>. The insert adaptor <NUM> can preferably have a material volume of greater than <NUM>% of a volume of said imaginary cylinder.

The imaginary circle IC can further define an adaptor circumscribing diameter DAC.

As also shown in <FIG>, the insert <NUM> comprises a single cutting edge <NUM> having a cutting edge thickness TI, measured parallel with the adaptor index axis IA, which is greater than the remainder of the insert <NUM>, when measured parallel with the adaptor index axis IA. The cutting edge thickness TI is greater than an adaptor thickness TA, measured parallel with the adaptor index axis IA, as required for parting off operations. The insert <NUM> can have an elongate shape as shown in <FIG>.

Referring to <FIG>, the tool holder <NUM> can comprise an elongated tool shank <NUM> and a tool head <NUM> extending therefrom.

The tool shank <NUM> can preferably be formed with a coolant inlet <NUM> that can be optionally closed with a plug <NUM> (<FIG>) when not in use.

The tool head <NUM> can comprise an adaptor recess <NUM> configured for receiving the insert adaptor <NUM> therein. The adaptor recess <NUM> can comprise at least one adaptor seating surface protuberance <NUM> which protrudes further than a remainder <NUM> of the adaptor recess <NUM> for stable contact with one of the insert adaptor's first and second sides 20A, 20B.

The tool head <NUM> can further comprise first and second tool bearing surfaces 64A, 64B protruding from the tool holder <NUM> along a periphery of an adaptor recess <NUM>.

In the side view of <FIG>, it is shown that the first tool bearing surface 64A can be straight (stated differently, follows a linear path). Whereas the other clamp surface, in this example the second tool bearing surface 64B comprises two contact areas 65A, 65B separated by a relief recess 65C, for more secure mounting of the insert adaptor <NUM>.

Imaginary tool bearing surface lines IT1, IT2 extending from the first and second tool bearing surfaces 64A, 64B can form an acute tool bearing surface angle A<NUM>.

The tool head <NUM> can further comprise a back-up bearing surface <NUM>.

At each end of the of the first and second tool bearing surfaces 64A, 64B and the back-up bearing surface <NUM>, relief portions <NUM> (also suffixed, e.g., first, second, third, fourth relief portions 67A, 67B, 67C, 67D) are formed to provide a gap between the second, third, fourth and fifth inserts 14B, 14C, 14D, 14E (or more precisely the cutting edges thereof) and the tool head <NUM>.

The tool head <NUM> can further comprise a tool hole <NUM>. The tool hole <NUM> can be internally threaded and also a through-hole (i.e. extending completely through the tool head <NUM>). Preferably, the tool hole <NUM> can be configured to bias the insert adaptor <NUM> in a biasing direction DB towards the back-up bearing surface <NUM> for particularly strong clamping.

Referring to <FIG>, a recessed tool head front surface <NUM>, which is preferably concave, can facilitate cutting depth. It will be understood that the cutting depth in this particular example extends to the first cutting depth DC1 limited by the screw <NUM> projecting from the insert adaptor <NUM>, but could potentially, in other embodiments, extend to a second cutting depth DC2 corresponding to a length to a rearmost portion of the tool head front surface <NUM>.

Referring to <FIG>, the screw <NUM> which has optionally preferred features is shown.

The screw <NUM> comprises a head portion <NUM> and a threaded shank portion <NUM>, and can have an overall screw length LS.

The head portion <NUM> can have a frustoconical shape as shown to reduce projection shown in <FIG>, and can comprise a tool-receiving configuration <NUM>.

A frustoconical surface <NUM> of the head portion <NUM> can form an angle A<NUM> of <NUM>° ± <NUM>°.

The shank portion <NUM> can comprise a threaded sub-portion <NUM> and a threadless sub-portion <NUM>.

The shank portion <NUM> can have a shank length LS1 at least three times greater than an adaptor thickness AT of the insert adaptor. Preferred values being recited above. It will be clarified that the shank length LS1 referred to only the part of the shank portion <NUM> comprising threading (for gripping the tool holder <NUM>), and does not include non-threaded portions as exemplified by a second shank length LS2, or a third shank length LS3 which is measured along the threadless sub-portion <NUM>.

The shank portion <NUM> can further comprise a tool-receiving configuration <NUM>.

Referring to <FIG>, a coolant channel <NUM> originating from the coolant inlet <NUM> (<FIG>) can extend under the adaptor recess <NUM>. In order to achieve flow to a narrow slit region during a parting off operation, the coolant channel <NUM> can open out at a coolant outlet <NUM> (see also <FIG> and <FIG>) aligned with and directly underneath a forwardmost portion of the adaptor recess <NUM>, and directed to an active cutting edge (<FIG>). The coolant channel <NUM>, in other words, requires a curved path to achieve the desired coolant outlet <NUM> position. Preferably there is only a single coolant outlet <NUM>. As shown, the coolant channel <NUM> can, using traditional channel forming methods such as drilling, comprise a number of straight coolant channel sections 84A, 84B, 84C, 84D. Although, under more recent additive manufacturing methods, the coolant channel <NUM> could be formed with one or more curved sections (not shown).

To further detail operation: one, or preferably each of the pockets <NUM> can have an insert <NUM> mounted thereto before the insert adaptor <NUM> is in the clamped position shown in <FIG> (preferably the inserts <NUM> are mounted while the insert adaptor <NUM> is not mounted at all to the tool holder <NUM>).

The insert <NUM> can be mounted to the pocket <NUM> by sliding it from the front end <NUM> of the pocket <NUM> towards the rear end <NUM> thereof which forces the opposing upper and lower clamp surfaces <NUM>, <NUM> to slightly separate, with the elasticity of the insert adaptor <NUM> causing them to resiliently clamp the insert <NUM> therebetween (notably the insert <NUM> is configured to preferably contact only the upper clamp surface <NUM> and the two contact areas 42A, 42B of the lower clamp surface <NUM>).

A tool, such as a soft face hammer (not shown) would typically be used for mounting. The pockets <NUM> may have a relative rigidity for resilient type pockets in view of the insert adaptor <NUM> preferably being free of elasticity grooves, which are omitted in preferred embodiments order to maintain sufficient insert adaptor constructional strength for ultra-thin parting off operations.

Thereafter, the insert adaptor <NUM> can be clamped to the tool holder <NUM> via fastening of the screw <NUM>. In an operational position the insert adaptor <NUM> contacts the tool holder <NUM> only via the first side 20A and exactly two of the straight bearing surfaces (e.g. the second and fourth bearing surface 52B, 52D. Notably, a gap <NUM> is typically designed between the insert adaptor <NUM> and the back-up bearing surface <NUM>.

In <FIG>, only the first insert 14A is in an operational position to part-off a workpiece (not shown) typically by the tool assembly <NUM> being moved in the operational direction DO shown.

After the first insert 14A is worn, either it can be replaced by being ejected (e.g. a portion of an ejection tool (not shown) can be inserted through the ejection gap <NUM> to eject the first insert 14A by a step of levering the ejection tool against the rear end <NUM>, and a different insert which is not shown can be inserted as described above) or by indexing of the insert adaptor <NUM>, until each of the inserts <NUM> are successively worn and then all replaced.

The insert adaptor <NUM> can be either removed completely for indexing or preferably a step of loosening the screw <NUM> (via either of the receiving configurations <NUM>, <NUM>) while maintaining partial attachment of the screw <NUM> to the tool head <NUM> is carried out. Subsequent to such loosening, the insert adaptor <NUM> is moved away from the tool head <NUM> such that it can be rotated without contacting the first and second tool bearing surfaces 64A, 64B and rotated to bring an adjacent insert <NUM> into an operative position. Subsequently, the insert adaptor <NUM> is moved back into contact with the tool head <NUM> and clamped via fastening of the screw <NUM>. Such indexing being user friendly due to the extremely low likelihood of falling parts.

Reference is made to <FIG>, an alternative tool assembly <NUM> is shown comprising of an insert adaptor <NUM>, an insert <NUM> and a tool holder <NUM>. Reference numerals for corresponding elements have been shifted by a value of "<NUM>".

The alternative tool assembly <NUM> is essentially similar to the previously described tool assembly <NUM>, except for three notable differences. The first notable difference is the use of non-centrally located screw(s) <NUM> (and screw hole(s) <NUM>) to hold the insert adaptor <NUM> to the tool holder <NUM>. The second notable difference is that the screw holes <NUM> are not tapered but are simple cylindrical bores. The third is the location of the operational insert <NUM> relative to the orientation of the bearing surfaces <NUM>.

Clearly there is also a different insert type and pocket, however, aside from described differences or clearly visible differences such as the insert type, it should be assumed that all the other functional features described above, as well the present notable differences, are applicable to any embodiment of the present invention. The focus on the description below will focus on the notable or visible differences, and undescribed portions can be assumed to correspond to those exemplified above.

Referring now also to <FIG>, the insert adaptor <NUM> comprises parallel adaptor first and second sides 120A, 120B connected by an adaptor peripheral surface <NUM>, and has an adaptor index axis IA extending through the center of the adaptor first and second sides 120A, 120B.

The adaptor peripheral surface <NUM> is formed with pockets <NUM> (also suffixed, e.g., first, second, third, fourth and fifth pockets 124A, 124B, 124C, 124D, 124E). It will be understood that each insert <NUM> (only one insert being shown, however clearly there can be several simultaneously mounted) and pocket <NUM> in the present example are identical and hence explanation will be limited to a single example thereof.

Using the fifth pocket 124E for explanation, it opens out to a front end <NUM>, and can comprise a rear end <NUM>, and opposing upper and lower clamp surfaces <NUM>, <NUM> extending between the front and rear ends <NUM>, <NUM>.

An ejection gap 136E (also suffixed, e.g., first, second, third, fourth and fifth ejection gaps 136A, 136B, 136C, 136D, 136E) can be defined between the clamping gap <NUM> and the rear end <NUM>.

Each ejection gap <NUM> can be accompanied by a release aperture <NUM> (also suffixed, e.g., first, second, third, fourth and fifth release apertures 137A, 137B, 137C, 137D, 137E). The fifth release aperture 137E being functionally connected to the fifth pocket 124E and fifth ejection gap 136E thereof.

As is known in the art, a tool with two projections (not shown) can be inserted into both the fifth ejection gap 136E and the fifth release aperture 137E to eject an insert <NUM> (not shown in the fifth pocket 124E but rather in the first pocket 124A).

Notably, as the release aperture <NUM> does not open out to the adapter peripheral surface <NUM> it does not weaken the insert adaptor <NUM> to the extent that an elasticity groove (not shown) would.

Now referring to the first pocket 124A, it can further be formed with an insert stopper surface <NUM>. The insert stopper surface <NUM> is located along the periphery of the insert adaptor <NUM> adjacent the front end <NUM> and the upper clamp surface <NUM>.

The insert adaptor <NUM> can be formed with a fastening configuration <NUM> which, differing to the previous example, is not in the center thereof. To elaborate, the fastening configuration <NUM> comprises one or more screw holes which in the present non-limiting example also have the dual function of being the release apertures <NUM>.

In the present example, in the operational position shown in <FIG>, there are three release apertures 137C, 137D, 137E (<FIG>) that function as screw holes when the insert <NUM> is in pocket 124A. Stated generally, the screw holes furthest from the insert <NUM> are used to maximize cutting depth obtainable.

The benefits of using a central fastening configuration <NUM> are mentioned above, for example, ease of indexability of the insert adaptor <NUM>, fewer components, less manufacturing related to components, greater ease to produce a smaller adaptor <NUM>. By contrast, the benefits of one or more non-centrally located screw holes (stated differently, circumferentially located screw holes) as exemplified here is that greater cutting depth is possible (the previous example being limited to the center of the adaptor due to the presence of the protruding screw).

Initially it was believed that the benefits of a single central fastening configuration <NUM> were superior. However, surprising benefits have also been found for the alternate arrangement. Since the inserts <NUM> (noting the particular insert shape is not important to this advantage) are easily ejected and replaced multiple times before the pocket <NUM> wears out, the detriment of completely removing all three screws <NUM> (e.g. <FIG>, also suffixed 118C, 118D, 118E) in order to index the insert adaptor <NUM>, is far less detrimental than for other designs (e.g. a single pentagonal insert with integral multiple edges spaced along the periphery thereof).

Thus the previously considered modest advantage of a slightly greater cut depth is not as significantly disadvantaged by multiple screws as was initially believed, further increasing the cost effectiveness of such insert adaptors.

In the present example the screw holes <NUM> are not tapered, nor are the screw holes <NUM> offset with the tool holder's tool holes <NUM> (also suffixed 168C, 168D, 168E). Stated differently, in the present example the screw holes <NUM> are simple cylindrical bores. Surprisingly, it has been found that even without the tapering and/or offset exemplified in the previous embodiment, which assists in biasing an insert adaptor onto a tool holder, appropriate clamping of the insert adaptor to a tool holder has been achieved. This is by far the simplest design, however certainly the option remains to taper and/or offset the screw holes (as in the previous example) to provide a biasing effect. All three options being feasible for any embodiment of the present invention.

It is also theoretically possible for an insert adaptor to comprise both screw holes and release apertures, or merely screw holes (depending on the method of insert removal) however, in embodiments where both release apertures and screw holes are used, it is clearly advantageous in terms of structural strength and production to have a combined function.

The adaptor peripheral surface <NUM> can be formed with a straight bearing surfaces <NUM> (also suffixed, e.g. first, second, third, fourth and fifth bearing surfaces 152A, 152B, 152C, 152D, 152E), i.e. in a side view (e.g. <FIG>) extending between the pockets <NUM>.

One of the notable differences mentioned above is the location of the operational insert <NUM> relative to the orientation of the bearing surfaces <NUM> (specifically the first bearing surface 152A directly below the insert <NUM>). As will be best understood from <FIG>, the first bearing surface 152A extends directly underneath the insert <NUM>. Stated differently the first bearing surface 152A in an operational position is essentially perpendicular to the operational direction DO. To elaborate, by comparison, in the previous example the bearing surface 52B was essentially parallel with the operational direction Do, whereas it can be seen that in the present example the corresponding lower bearing surface forms an acute lower surface bearing angle α the operational direction DO. The angle α is preferably fulfills the condition: <NUM>° < α < <NUM>°, more preferably <NUM>° < α < <NUM>° and most preferably <NUM>° < α < <NUM>°.

It will be understood that such orientation provides better support underneath an insert. This is achieved by rotating the bearing surfaces <NUM> relative to the pocket <NUM> positions (relative to the previous example). This advantageous rotation can also optionally be incorporated for other insert types such as that shown in the previous example. However, for the angled insert type shown in the present figures such orientation is believed necessary.

A further improvement in the bearing surface <NUM> is that it can comprise an optional but preferred recessed portion <NUM> directly adjacent the insert <NUM>. The bearing surface <NUM> can thus comprise a recessed portion <NUM>, a transition portion <NUM> and a non-recessed portion <NUM>.

By not having an entirely straight bearing surface <NUM>, but including a recessed portion <NUM>, any deformation caused by the insert <NUM> (caused by impacts during machining) more significantly affects the recessed portion <NUM> rather than the non-recessed portion <NUM>. Thus no deformation or at least less deformation occurs in the non-recessed portion <NUM> used for abutment with the tool holder <NUM>. Clearly, this feature can be beneficially incorporated into any embodiment.

Referring to <FIG>, the tool holder <NUM> is generally similar, the notable difference being the three tool holes tool holes <NUM> and the rotated tool bearing surfaces 164A, 164B which are configured to contact the non-recessed portions <NUM> of each bearing surface <NUM>. The remaining features are generally similar to the previous example.

Claim 1:
An insert adaptor (<NUM>) for parting off having an adaptor index axis (IA) and comprising:
parallel adaptor first and second sides (20A, 20B) connected by an adaptor peripheral surface (<NUM>) which extends peripherally around the insert adaptor (<NUM>);
the adaptor index axis (IA) extending through the center of the first and second sides (20A, 20B); characterized in that
the adaptor peripheral surface is formed with three to five pockets (24A, 24B, 24C, 24D, 24E) and bearing surfaces (<NUM>) extending between the pockets (24A, 24B, 24C, 24D, 24E);
each of the pockets (24A, 24B, 24C, 24D, 24E) is configured for resilient clamping and comprises resilient upper and lower clamp surfaces (<NUM>, <NUM>);
in a side view of the insert adaptor (<NUM>), the bearing surfaces (<NUM>) are straight bearing surfaces extending between the pockets (24A, 24B, 24C, 24D, 24E); and
the pockets (24A, 24B, 24C, 24D, 24E) are equally circumferentially spaced about the adaptor peripheral surface (<NUM>),
wherein the insert adaptor is made of metal.