Patent Description:
In the current field it is known that the damping effect, or vibration suppression, created by a damping mechanism in a turning tool is influenced mainly by three parameters: A) Damping member weight; B) Distance between a damping member center of mass and the clamping portion which is secured in a CNC machine; and C) Turning tool stiffness. To maximize the damping effect, these parameters are optimized/chosen per the machining application and/or turning tool geometry. In most scenarios, all three parameters are preferably maximized.

Typical damped turning tools of the field have a relatively large length-to-width ratio, and have clamping and cutting portions and a tool body which extends therebetween. In a clamped position in the CNC machine, at least a portion of the clamping portion is rigidly clamped in the CNC machine, while the tool body and cutting portions are cantilevered therefrom. A typical damping mechanism includes a confined, elongated damping member which lies within a damping cavity, or damping recess, along the elongated tool body. The damping member interacts with the turning tool via a viscous and/or elastic material. To maximize the size/weight of the damping member, the required damping recess leaves the tool body with only a thin peripheral envelope. This type of damping mechanism considerably reduces tool stiffness compared to tools with a solid/full tool body which does not include a damping mechanism therein. In summary, the above described damped turning tools maximize the damping member weight, at the expense of tool, or tool body, stiffness and the distance between the damping member center of mass and the clamping portion.

Generally, an effective non-damped turning tool, among other features, must have an appropriately rigid structure and should be cost-efficient. Designing such a tool becomes even more complex, when a damping mechanism is to be implemented. Specifically - finding an appropriate location, orientation and/or enough space for a sufficiently heavy damping member while both preserving tool structure rigidity and proper tool clearance. The current invention provides a vibration damping solution for external turning tools which overcomes the aforementioned problems.

The invention is defined by the features of claim <NUM>. Preferred embodiments are defined by the features of the dependent claims.

Any of the following features, either alone or in combination, may be applicable to any of the above aspects of the subject matter of the application:.

The damping member angle can range between <NUM> and <NUM> degrees.

The turning tool has a tool axis which extends centrally within the tool body parallel to the axial direction and the damping member has a center of mass which is offset from the tool axis.

The damping member has a max member length measured between extremities of the damping member along the elongation axis; and the max member length is larger than a max member thickness measured between extremities in a direction perpendicular to the elongation axis.

The max member length is at least <NUM> times larger than the max member thickness.

The damping member is replaceable with damping members of different weights, each configured, or calibrated, for a specific, or range of damping scenarios.

The damping recess has a recess elongation axis which forms a non-zero damping recess angle with the axial direction.

The cutting portion includes a turning insert, and in a top view of the turning tool, the center of mass of the damping member and the turning insert are located on opposite sides of the tool axis.

The damping mechanism can have an elastic member.

The damping mechanism can have a lid and a calibration mechanism which is configured to apply a permanent force onto the damping member against an elastic member.

The damping member can be entirely confined within the cutting portion. Thus, no portion of the damping member <NUM> is visible in any view of the cutting portion. Also, the damping member does not extend in a rearward direction into the clamping portion.

The damping member can have chamfers at opposite ends thereof.

The cutting portion has opposite cutting portion side surfaces, and the elongation axis can extend therebetween without intersecting the cutting portion side surfaces.

The damping member can have unitary one-piece construction.

The turning insert has a cutting edge formed at an intersection between an upward-facing rake surface and a forward-facing and/or side-facing relief surface.

The elongation axis can extend parallel or substantially parallel to the relief surface.

The turning tool has coolant conveyance assembly with coolant channels which extend at least through the cutting portion.

The cutting portion can have a different axial cross-sectional shape than that of the tool body.

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:.

Where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

In the following description, various aspects of the subject matter of the present application will be described. For purposes of explanation, specific configurations and details are set forth in sufficient detail to provide a thorough understanding of the subject matter of the present application. However, it will also be apparent to one skilled in the art that the subject matter of the present application can be practiced without the specific configurations and details presented herein.

Attention is drawn to <FIG>. A turning tool <NUM> configured to suppress vibrations includes an elongated tool body <NUM> and a turning insert <NUM> secured in a pocket <NUM>. The pocket <NUM> is configured to accommodate the turning insert <NUM>. The turning insert <NUM> has at least one cutting edge <NUM> formed at a meeting between an upward-facing rake surface <NUM> and a forward-facing and/or side-facing relief surface <NUM>. The turning tool <NUM> has, at opposite extremities of the tool body <NUM>, a clamping portion <NUM> and a cutting portion <NUM>. The cutting portion <NUM> further includes a damping mechanism <NUM>. The elongated tool body <NUM> defines a longitudinal, or axial direction AD. The term longitudinal, or axial direction refers to any axis which is parallel to an elongation direction of the tool body <NUM>. Specifically, the axial direction AD can be determined by a projection direction of the tool body <NUM> which is cantilevered from a CNC machine. The turning tool <NUM> is secured, or coupled into the CNC machine via the clamping portion <NUM>. The axial direction AD can also be perpendicular to a rotation axis of the machined workpiece.

The tool body <NUM> also defines a centrally extending tool axis T which is parallel to the axial direction AD and passes centrally through the tool body <NUM>. According to the present embodiment, the tool axis T and the axial direction AD both pass through the clamping and cutting portions <NUM>, <NUM>.

The clamping portion <NUM> is configured to be clamped in a CNC machine, and can have a square cross section taken perpendicular to the tool axis T (axial cross section). When clamped in the CNC machine, the clamping portion <NUM> is considered as a rigid, static reference point with regard to references to vibration damping in the turning tool <NUM>.

Attention is drawn to <FIG>, <FIG> and <FIG>. The tool body <NUM> has a body peripheral surface <NUM> which extends along the axial direction AD between the clamping and cutting portions <NUM>, <NUM>. Specifically, the axial direction AD is parallel to the body peripheral surface <NUM>. According to the present embodiment, the body peripheral surface <NUM> has opposite body top and bottom surfaces <NUM>, 30and opposite body side surfaces <NUM> which extend between the body top and bottom surfaces <NUM>, <NUM>. The body peripheral surface <NUM> can have a square axial cross section taken perpendicular to the axial direction AD. The tool axis T and the axial direction AD are parallel to the body side surfaces <NUM>. The tool axis T and the axial direction AD are also parallel to the body top and bottom surfaces <NUM>, <NUM>. The tool axis T can be located midway between the body side surfaces <NUM>. The tool axis T can be located midway between the body top and bottom surfaces <NUM>, <NUM>.

Attention is drawn to <FIG> and <FIG>. The turning tool <NUM> has a maximum tool width TW which is measured between outward extremities of the turning tool body <NUM> in a direction perpendicular to the body side surfaces <NUM> and in a direction perpendicular to the tool axis T. The turning tool <NUM> further has a maximum tool height TH which is measured between outward extremities of the tool body <NUM> in a direction parallel to the body side surfaces <NUM> and in a direction perpendicular to the tool axis T.

The turning tool <NUM> has a height to width ratio HWR = TH/TW which is smaller than <NUM> and preferably smaller than <NUM>. According to the present embodiment, the height to width ratio HWR is <NUM>. This dimension ratio relates to available volume (internal or external) in the turning tool <NUM> where a damping mechanism <NUM> can be implemented efficiently. Most, if not all blade-shaped tools have a height to width ratio of upwards of <NUM>. Parting, or cut-off blade shaped tools are therefore too narrow to internally include a damping mechanism <NUM> according to the present invention. Specifically, an elongated damping member <NUM> according to the present application which has an appropriate and effective weight cannot be implemented or be accommodated internally within a blade-shaped machining tool simply because it will not fit.

Attention is drawn to <FIG>. The cutting portion <NUM> extends from the tool body <NUM>. The cutting portion <NUM> has cutting portion top and bottom surfaces <NUM>, <NUM> which extend from a tool front surface <NUM> towards the clamping portion <NUM>. The cutting portion <NUM> further has cutting portion side surfaces <NUM> which extend between the cutting portion top and bottom surfaces <NUM>, <NUM>. The cutting portion <NUM> includes at least one pocket <NUM> and a turning insert <NUM> secured therein. The cutting portion <NUM> can further include a coolant conveying assembly <NUM> and coolant channels <NUM> which extend at least through the cutting portion <NUM>. According to the present embodiment, the cutting portion <NUM> has a different axial cross section shape than that of the tool body <NUM>. According to the present embodiment, the cutting portion <NUM> extends in the axial direction AD with the pocket <NUM> formed at the forwardmost axial end of the cutting portion <NUM>.

According to the present embodiments, the damping mechanism <NUM> includes an elongated damping recess <NUM>, an elongated damping member <NUM>, at least one elastic member <NUM>, a calibration mechanism <NUM> and a lid <NUM>.

Attention is drawn to <FIG>. According to the present embodiment, the damping member <NUM> is entirely confined within the cutting portion <NUM>. Stated differently, in the present example, no portion of the damping member <NUM> protrudes outwardly from the cutting portion <NUM>. Thus, no portion of the damping member <NUM> is visible in any view of the cutting portion. Also, the damping member <NUM> does not extend in a rearward direction into the clamping portion <NUM>. The damping member is made from a material with a relatively high density to achieve a high weight-to-volume ratio. The damping member <NUM> can be made of Tungsten. In the current example, the damping member <NUM> is made of a single piece of material and thus has unitary one-piece construction.

The damping member <NUM>, and especially a center of mass CM thereof, is located adjacent the tool front surface <NUM> at a location which is farthest possible from the clamping portion <NUM>. In the present embodiments, the pocket <NUM> and the damping mechanism <NUM> at least partially overlap in the axial direction AD. In other words, a plane P perpendicular to the axial direction AD intersects both pocket <NUM> and the damping mechanism <NUM>.

These orientation-related features relate to advantageous design which places the damping mechanism <NUM> at the cutting portion <NUM> to avoid compromising the structural integrity and/or stiffness of the tool body <NUM>.

Attention is drawn to <FIG>. The damping member <NUM> can have first and second end surfaces <NUM>, <NUM> and a member peripheral surface <NUM> which extends therebetween. According to the present embodiment, the member peripheral surface <NUM> does not include a thread. The damping member <NUM> has a central elongation axis E which passes through the first and second end surfaces <NUM>, <NUM>. The elongation axis E extends in a damping member elongation direction. The elongation axis E forms a non-zero damping member angle α with the axial direction and with the tool axis T (<FIG>). The damping member angle α ranges preferably between <NUM> and <NUM> degrees. In the present example, the damping member angle α is <NUM> degrees. The damping member angle α can be determined by tool geometry, i.e., in accordance with design efforts to maximize the available space/volume for the damping member <NUM> and consequently - its weight. The damping member angle α, can also be affected by other recesses in the cutting portion <NUM> such as the pocket <NUM> and/or coolant conveying assembly <NUM>. Furthermore, in an axial view along the tool axis T, the orientation of the damping member <NUM>, and consequently the elongation axis E is preferably upright, as seen in <FIG>. In other words, in the present embodiments, the elongation axis E extends between the cutting portion side surfaces <NUM> without intersecting either. In the present embodiments, as seen in <FIG>, the elongation axis E is parallel, or substantially parallel to the tool front surface. According to the present embodiments, during machining, the elongation axis E extends parallel, or substantially parallel, to an operative relief surface <NUM> which extends from an operative cutting edge <NUM> that cuts the workpiece.

According to the present example, the member peripheral surface <NUM> has a cylindrical shape, the central axis of which coincides with the elongation axis E. The center of mass CM is defined by a vertex. According to the present embodiment, the center of mass CM lies on the elongation axis E. According to the present embodiments, the damping member <NUM> is not centered with respect to the tool body <NUM>. In other words, in the present embodiment, the center of mass CM does not lie in the tool axis T. Specifically, in a top view of the cutting portion <NUM>, or a plan view of the cutting portion top surface <NUM> (as seen in <FIG>), a projection of the center of mass CM is offset from the tool axis T. This is advantageous, since the deviation, or lever arm, of the damping member <NUM> with respect to the tool axis T enables the damping member <NUM> to generate a suppression counter torque against torsional vibrations generated by machining forces. This is true in the present embodiments where the pocket <NUM> is also not centered with respect to the tool axis T. According to the present embodiment, in a top view of the cutting portion <NUM>, or a plan view of the cutting portion top surface <NUM>, as shown in <FIG>, the center of mass CM and the turning insert <NUM> are preferably located at opposite sides of the tool axis T. As seen in <FIG>, the center of mass CM is not located directly beneath, or under, the turning insert <NUM>. In other words, in a plan view of the rake surface <NUM>, the center of mass CM does not overlap a projection of the turning insert <NUM>.

The damping member <NUM> has a maximum member length ML measured between extremities of the damping member <NUM> along the elongation axis E. The damping member <NUM> also has a maximum member thickness MT measured between extremities thereof in a direction perpendicular to the elongation direction. It is understood that when the damping member <NUM> has a cylindrical body, the maximum member thickness MT corresponds to the diameter of the cylindrical body. The maximum member length ML is larger than the maximum member thickness MT. The maximum member length ML is preferably <NUM> times larger than the maximum member thickness MT. In other words, the damping member <NUM> has a length to thickness ratio ML/MT = LTR > <NUM>. According to the present embodiment, the length to thickness ratio LTR is <NUM>. This ratio relates directly to optimization of the shape of the damping member <NUM> to the available volume and to production restrictions in turning tools having a non-blade-shaped cutting portion. Specifically, the elongated shape has a bigger rotational inertia than, e.g., a spherical or a cube shaped damping member. In addition, the elongated shape enables compactness, while avoiding various mechanisms of the turning tool <NUM> such as an insert clamping mechanism in the pocket <NUM>, or coolant channels <NUM>. In the current turning tool <NUM>, it was found that the current position and orientation of the damping mechanism <NUM> is preferable in terms of maximum weight achieved in a relatively small confined volume, production efficiency and damping test results (as shown in <FIG>). As previously mentioned, increasing the damping member <NUM> weight and distance from the clamping portion <NUM> becomes more significant as the distance between the cutting portion <NUM> and the clamping portion <NUM> increases, i.e., longer tools means larger projection from the CNC machine which leads to an increase in vibrations caused by machining.

The damping member <NUM> can have two chamfers <NUM>. Each chamfer <NUM> extends between the member peripheral surface <NUM> and each of the first and second end surfaces <NUM>, <NUM>. In a cross section along the elongation axis E, the chamfer <NUM> can appear straight. Each chamfer <NUM> is configured to abut the elastic member <NUM>.

The damping recess <NUM> is elongated and configured to accommodate the elongated damping member <NUM>. According to the present embodiment, the damping recess <NUM> is a blind hole, or recess, i.e., includes only a single opening <NUM>. According to the present embodiment, the damping recess <NUM> only opens out to, and the opening <NUM> is located in, the cutting portion bottom surface <NUM>. This allows for a clean, protrusion-free, cutting portion top surface <NUM> which gives way for uninterrupted chip flow. Furthermore, this smooth upper surface is subjectively aesthetic, which is regarded as advantageous in terms of marketing value.

Attention is drawn to <FIG> and <FIG>. The damping recess <NUM> has a recess elongation axis RE. The recess elongation axis RE forms a non-zero damping recess angle β with the axial direction AD. The damping recess angle β ranges preferably between <NUM> and <NUM> degrees. According to the present embodiments the damping recess angle β measures <NUM> degrees. It is understood that when the damping mechanism <NUM> is installed and the tool is non-operative, the damping member's elongation axis E and the recess elongation axis RE are aligned.

The damping recess <NUM> can have a recess wall <NUM> which extends from a recess base surface <NUM> located at an inner-most portion of the damping recess <NUM> along the elongation axis RE. The recess wall <NUM> can be cylindrical. The recess wall <NUM> can open out to the body bottom surface <NUM>. At or adjacent the opening <NUM>, the recess wall <NUM> can have a recess female thread <NUM> configured to receive and correspond with an external male lid thread <NUM> of the lid <NUM>. The lid <NUM> can also have an internal female lid thread <NUM> which is configured to receive and correspond with an adjustment screw <NUM>, as will further explained below.

According to the present embodiment, the damping mechanism <NUM> has two elastic members <NUM>. Each elastic member <NUM> can abut a respective chamfer <NUM>. Each elastic member <NUM> can be an elastic O-ring made of rubber.

According to the present embodiment, in an assembled position of the damping mechanism <NUM>, the calibration mechanism <NUM> can include, in the following order: a pressure plate <NUM>, the adjustment screw <NUM>, the lid <NUM> and a locating nut <NUM>. The pressure plate <NUM> is located between a first end of the adjustment screw <NUM> and the elastic member <NUM>, the adjustment screw <NUM> is threaded into the internal female lid thread <NUM>, and the locating nut <NUM> is threaded at a second end of the adjustment screw <NUM>. Once the lid <NUM> has been firmly tightened into the recess female thread <NUM>, the adjustment screw <NUM> can be turned to calibrate the damping mechanism <NUM>, i.e., to adjust the amount of force exerted onto the respective elastic member <NUM> via the pressure plate <NUM> which spreads the forces across the elastic member <NUM>. Once the damping mechanism <NUM> has been properly calibrated, i.e., the desired force has been achieved, the locating nut <NUM> is tightened to preserve the current calibration, or adjustment screw <NUM> location.

Claim 1:
A non-blade shaped external turning tool (<NUM>) comprising:
an elongated tool body (<NUM>) having opposite clamping and cutting portions (<NUM>, <NUM>) defining an axial direction (AD) therebetween;
a damping mechanism (<NUM>) at the cutting portion (<NUM>), the damping mechanism (<NUM>) comprising an elongated damping member (<NUM>) having an elongation axis (E); and
a turning insert (<NUM>) removably retained in a pocket (<NUM>) of the cutting portion (<NUM>); wherein:
the elongation axis (E) forms a non-zero damping member angle (α) with the axial direction (AD);
the cutting portion (<NUM>) has opposite cutting portion top and bottom surfaces (<NUM>, <NUM>) and an elongated damping recess (<NUM>) configured to accommodate the damping member (<NUM>); and:
the damping recess (<NUM>) opens out to exactly one of the cutting portion top and bottom surfaces (<NUM>, <NUM>);
characterized in that:
a plane (P) perpendicular to the axial direction (AD) intersects both the turning insert (<NUM>) and the damping mechanism (<NUM>).