Rotating tool holder assembly for modulation assisted machining

Assemblies, apparatus, and methods are described for designing modulation tool holder assemblies and installations for modulation-assisted machining, and, in particular, for rotating machining applications that benefit from the sinusoidal modulation motion while cutting fluids are simultaneously applied through the tool. In addition, the design of rotating modulation tool holder assemblies and systems is described. In a tool holder assembly for modulation in a rotating spindle, the electric power and/or control signals are transferred from an external source to the modulation tool holder assembly installed in the rotating machine spindle. Similarly, the high-pressure cutting fluid is transferred from a stationary source to the rotating tool holder assembly for modulation.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to machining equipment, and more particularly to machining equipment that employs a rotating tool to perform a function on a workpiece, such as a cutting, drilling or the like.

BACKGROUND OF THE INVENTION

Modulation-Assisted Machining tool holder assemblies and methods for use in machining processes are known in the art and can improve machining performance. An example of a modulation assisted machining tool holder is shown in Mann et al., U.S. Pat. No. 7,587,965—Tool Holder Assembly and Method for Modulation-Assisted Machining. Such a device can also create machined chips with controlled size and shape, as described in Mann et al., U.S. Pat. No. 7,628,099—Machining Method to Controllably Product Chips with Determinable Shapes and Sizes. Modulation-assisted machining systems superimpose a controlled oscillation onto conventional machining processes—for example, turning, boring, drilling, trepanning, parting, or grooving.

The method of modulation-assisted machining creates an intermittent separation (gap) between the tool and the work piece, altering the mechanics of the machining process as described in Mann et al., U.S. Pat. Nos. 7,587,965 and 7,628,099. The modulation can be composed of two principal orientations of oscillation: (1) in the direction of the cutting velocity (velocity-direction modulation) or (2) in the direction of the undeformed chip thickness (feed-direction modulation). Then, the modulation can be effected in either of these principal orientations or in an orientation that is a combination of these principal orientations.

Additionally, the application of appropriate modulation conditions in the principal feed direction has the unique attribute of dividing the removed materials into a series of discrete cutting events, since the undeformed chip thickness reaches a value less than or equal to zero during each cycle of modulation. Application of appropriate modulation conditions in the principal cutting velocity direction causes the instantaneous cutting velocity to become less than or equal to zero.

Regardless of the orientation of modulation, if the modulation conditions are effective, the cutting process is intermittently interrupted during each cycle of the modulation. This interruption can have a number of important benefits for the machining process, including chip control, enhanced effectiveness of cutting fluids, reduced cutting tool wear rates, and reduction in cutting temperatures.

However, the systems and methods described in U.S. Pat. Nos. 7,587,965 and 7,628,099 are effectively limited to a stationary orientation of the tool holder assembly and interconnected components, such that the workpiece rotates while the tool remains stationary. While a stationary tool and rotating workpiece assembly can be useful in some machining situations, certain machining scenarios benefit greatly from an assembly capable of tool rotation during the machining process rather than (or in addition to) workpiece rotation. For example, it is likely far easier to use a rotating tool assembly to perform a drilling operation on a large work piece (e.g. transmission casing) than to rotate a large work piece. These rotating tools are often associated with a computer controlled machining center. A rotating tool poses major design and engineering challenges to provide the proper electrical power and/or control signals to the rotating linear actuator of the modulation tool holder assembly.

Prior art has described possible methods of wireless power using telemetry. See DE10343682 (A1), ASCHENBACH Bernd (author),Mechatronisches Werkzeugsystem zur Fräs und Bohrungsbearbeitung[Mechatronic tool system for milling and boring operations.] The prior art has also described other non-contact inductive power methods. See, J. Pi and X. P, Xu, “Design of Integration Tool-Holder System for Ultrasonic Vibration Machining Using Contactless Inductive Power Transfer”,Advanced Materials Research, Vol. 69-70 (2009) pp 520-524.

However, these methods may not be practical for implementation. Further, these methods may not resolve important aspects of the power signal levels, signal quality, and/or feed-back to the external power source of the computer controls of the parent machine tool itself.

Another difficulty faced in the design and engineering of a rotating tool assembly is dealing effectively with machining environments that often include cutting fluids (e.g., oils) and material contaminants that are used and produced during machining processes.

Thus, difficult design and engineering challenges are posed when trying to create a device that will provide simultaneous rotation to the tool holder assembly, while isolating such power and control systems (including the additional linear actuator used in modulation-assisted machining), from high-pressure cutting fluids during the machining operation. To date, the practical commercial implementation of these alternative methods discussed in Pi and Xu; and in DE20031043682 for control of modulation tool holders has not been realized.

One object of the present invention is to provide a device that addresses these needs.

SUMMARY

The present invention discloses technologies relating to machining equipment, and more particularly to rotating tool holder assemblies used during a machining process.

The industrial application of the inventions described in U.S. Pat. Nos. 7,587,965 and 7,628,099 can be improved by developing a tool holder assembly for modulation that is capable of rotating during modulation. By engineering and implementing new modulation tool holder assemblies, the friction, wear and lubrication of metal cutting and the chip formation process can be controlled in novel ways that are unachievable by existing known machining processes. The present invention provides the ability to prescribe the effective modulation conditions for improved machining processes as described in U.S. Pat. No. 7,587,965 or for the control of chip formation as described in U.S. Pat. No. 7,628,099. Moreover, rotating systems for modulation-assisted machining provide a means to implement the technology across a significantly broader range of industrial machine tools.

Additionally, the present invention discloses a more robust method for supplying electrical power and control signals to/from a rotating “live” modulation tool holder assembly through a rotary electrical connector. A general requirement for modulation tool holder assemblies is the use of electrical wire to commute power and/or various control or monitoring signals to the respective linear actuator of the modulation tool holder assembly. Additional wires may be required to communicate signal or feedback control information between the rotating modulation tool holder assembly and a stationary external power or control system in the machine tool.

Prior known modulation-assisted machining assemblies do not allow for tool rotation as allowed by the present invention. Typically the prior art employs permanent or semi-permanent fixed associated components, such as wire leads that directly connect to the linear actuator. However, in a rotating tool system, such direct connection is not possible without employing novel components for providing electrical contact, such as those described herein.

The present invention discloses a device wherein electrical power is continuously and reliably provided using, for example, a novel electrical contact where liquid mercury is employed to create a contact circuit between a power source connected to a stationary assembly and the rotating spindle of the machine tool. In addition to providing a novel solution to provide power or control signals to and from the modulation tool holder assembly, the rotating electrical connector is very compact in size, has no moving parts, and enables relatively high rotational speeds and longer operating life, in comparison to the contacts in a conventional contact slip ring systems (e.g. copper or graphite brushes).

Along with the electrical power and/or signal control requirements for a rotating modulation tool holder assembly, the assembly must often be capable of delivering high-pressure cutting fluids (e.g., oils and water-based soluble oils) to cutting tools (e.g., drills) installed in the modulation tool holder assembly. The present invention addresses this need through the use of a highly inventive rotating union, comprised of a rotating section and a stationary section. High-pressure cutting fluid (e.g., oil, air, or aqueous-based fluids) can be supplied through a connector on the stationary section of the hydraulic union.

Additionally, the present invention introduces a rotary hydraulic coupling assembly that enables the rotating hollow wiring shaft from the modulation device to pass directly through the axis of the stationary section of the rotary union supplying the high-pressure fluid.

In some implementations, this special configuration utilizes a linear bearing sleeve (such as a bronze bearing or miniature roller bearing) installed into the rotary coupling to maintain the centric position of the shaft while supporting the rotary motion. In such implementations, the sleeve is simultaneously coupled with one or more rotary shaft seals that prevent fluid leakage.

Thus, the present invention provides for simultaneous rotation of a tool holder assembly in modulation-assisted machining, while also providing power and control wires through the rotating assembly and providing high-pressure cutting fluid through the assembly in a manner that protects and isolates the modulation components—for example, the power and control wires and the linear actuator—during the machining process.

DETAILED DESCRIPTION

Before the present methods, implementations, and systems are disclosed and described, it is to be understood that this invention is not limited to specific synthetic methods, specific components, embodiments, particular compositions, dimensions, and as such, may vary. It is also to be understood that the terminology used herein is chosen and employed for the purpose of describing particular implementations only and is not intended to be limiting.

As used in the specification and the claims, the singular forms “a,” “an” and “the” include plural components unless the context clearly dictates otherwise. Ranges may be expressed in ways including from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another implementation may include from the one particular value and/or to the other particular value.

Similarly, when values are expressed as approximations, for example by use of the antecedent “about,” it will be understood that the particular value forms another implementation. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. Similarly, “typical” or “typically” means that the subsequently described event or circumstance often though may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

As will be discussed below, the present invention is a rotating tool holder assembly to be used in Modulation-Assisted Machining. The present invention improves upon the devices and methods disclosed in U.S. Pat. Nos. 7,587,965 and 7,628,099, which are incorporated by reference.

The linear actuator11in a modulation tool holder assembly10is controlled by power and/or control signals transmitted from an external power source or control system102. In conventional machining processes, the material removal is accomplished by cutting tools held by a (non-modulating) tool holder assembly installed into the machine tool spindle or tool block (e.g., milling machine or lathe). In conventional machining, the cutting process is relatively continuous. In modulation-assisted machining, the application of a controlled, low-frequency sinusoidal oscillation (i.e., modulation, typically <1000 cycles per second to the tool or workpiece) divides the otherwise continuous cutting process into a series of discrete cutting events wherein the tool engages with and disengages from the work piece.

These discrete cutting events alter the mechanics of the machining process and offer unique benefits for the machining process, including the control of chip formation and improved tool wear. The modulation tool holder assembly11may be stationary in a lathe machine (i.e., non-rotating, as described in U.S. Pat. No. 7,587,965). In the present invention, the tool holder assembly can be designed to rotate when installed in the spindle of a machining center or other rotating system.

The modulation tool holder assembly of the present invention is designed for use with actuators such as piezoelectric actuators, magnetostrictive actuators, or linear motors such as described in U.S. Pat. Nos. 7,587,965 and 7,628,099 for enabling the tool to move in a cyclic, linear manner. Such linear actuations require that electric power and/or control signals be supplied to the linear actuator simultaneously with the rotational action to enable the tool both to rotate and to move linearly. Machining processes that employ rotating tools are commonly referred to as “live” machining operations.

The tool holder is typically rotated in a spindle while it is simultaneously fed into or traversed through a work piece causing the removal of material from the work piece by the tool. Examples of tools employed in machining processes include drills, reamers, boring tools, threading tools, milling tools, grinding tools, or broaching tools. The rotating tools remove material from a work piece which itself may be stationary or simultaneously moving (e.g., rotating or translating).

In these complex machining systems, the implementation of modulation assisted machining may be accomplished using a tool holder assembly for modulation that is adapted to and/or integrated into a rotating spindle of the machine tool.

A tool holder assembly10of the present invention is represented inFIG. 1(a), that discloses the “live” rotating modulation tool holder assembly10of the present invention. Tool holder assembly10includes a proximal or machine engaging end104and a distal, or tool engaging end106. The machine engaging end104is typically engaged to the machine (not shown) that operates the tool holder assembly10. The tool engaging end106is provided for engaging a tool12that engages a work piece (not shown) wherein the tool12performs an operation on the work piece. The tool holder assembly10also includes a major axis108that extends between the machine engaging proximal end104and the tool engaging distal end106and serves as the axis of rotation for the rotating components of the tool holder assembly10.

The tool holder assembly10is a rotating or “live” modulation tool holding assembly that permits both power and fluid to be transferred with the tool assembly110from the proximal or machine end104to the distal or tool engaging end106. In the modulation tool assembly10ofFIG. 1, the components are sized and configured to permit high-pressure fluid to pass through the tool holder assembly10from the proximal end104to the distal end, while causing the fluid to remain spatially separated from the linear actuator11. The path of the fluid in the tool holder assembly10is denoted by arrows running from the proximal end104to the distal end106.

As will be described in more detail below, the tool holder assembly10includes a series of passageways, including the annular array of axially extending passageways13that are formed in the body14, annular washer shaped, radially extending ring grooves15, an annular array of axially extending sleeve passageways17that are formed as a part of sleeve16, radially inwardly extending portholes20, the proximal end of tool12receiving cavity202and the axially extending central passageway122that extends between the proximal end124and the distal, or work piece engaging end126of tool12. As will be noted, the passageways13,15,17,20,202,122route the fluid through spaces relatively close to the radially outwardly facing exterior surface of the tool holder assembly10, so as to minimize any interaction between the fluid and the linear actuator11.

The passageway122through the longitudinal axis100of the cutting tool12provides high-pressure fluid (e.g., cutting fluid) to the surface of the work piece being cut. This cutting fluid helps to lubricate the cutting operation, keep the work piece and tool12cool, and helps to flush dislodged cutting debris away from the surface of the work piece.

A tool holder nose19is used to mechanically connect and/or affix the appropriate cutting tool12. A variety of toll holder noses19exist and include such things as collets, chucking devices, tool clamping devices, etc. As shown in the drawing, the tool nose19includes an axially extending, radially inwardly facing wall192that defines an interior passageway that includes cavity202. The radially inwardly facing cylindrical wall192is sized and configured for engaging an axially extending, radially outwardly facing wall of the tool12, and snugly engaging said tool12so that rotation of the tool nose19causes rotation of the tool12. The proximal end of the tool12and the axial extending passageway of the tool nose19define passageway202, that collects the high pressure fluid and directs the high pressure fluid axially distally out the axially extending passageway122of tool12.

The nose19also includes a radially outwardly facing, axially extending surface having a relatively enlarged diameter proximal portion194and a relatively reduced diameter distal portion196. The proximal portion surface194includes a pair of annular, radially circumferential channels for receiving O-rings22to help prevent fluid leakage out of radially extending port holes20.

The radially outwardly facing surface194is sized and configured for receiving the radially inwardly facing surface of sleeve16in a fluid tight arrangement.

The body14includes a relatively reduced diameter proximal portion142, and a relatively enlarged diameter distal portion144. The proximal portion142of the body14comprises a thickened tube having an axially extending, radially inwardly facing surface146that defines an interior passageway (interior surface)148that is sized and configured for receiving the linear actuator11therein.

The radially outwardly facing surface150is generally cylindrical in configuration and is sized and configured for being received by the radially inwardly facing surface232of step23. The radially extending, proximal end surface154includes an annular array of ports132that comprise the upstream opening of axially extending, fluid containing body passageways13. The passageways13extend within the interior of the body14, between the radially inwardly facing surface146, and the radially outwardly facing surface150. The passageways extend throughout substantially the entire length of the proximal portion142of the body14.

The distal ends of the body passageways13terminate at the ring groove15that essentially comprises an annular trough formed in the radially extending proximal surface of sleeve16. Ring groove15provides a channel for permitting fluid exiting from the distal end of passageway13to flow radially outwardly into the proximal ends172of sleeve16passageway17.

As an alternative to the annular array of passageways13, other embodiment may employ for example, a single layer, multiple passageway or a pair of semi-annular space sufficient to provide passage for fluids. As depicted, these passageways13terminate distally at the annular ring groove15formed in the radially extending proximal surface154of the body.

Alternatively, other types of passageway13and groove15configurations may be useable.

One wall of the annular ring groove15is provided by a radially extending axially distal facing surface of sleeve16. The annular ring groove15receives fluid from passageways13to create a fluid manifold. As depicted, the outer sleeve16includes a series of axial extending passageways17disposed generally parallel to the major axis108of the sleeve16. The placement of fluid passageways17in sleeve16enables the high-pressure fluid to pass radially outwardly of and not through or in contact with outside the rotary ball-spline bearing assembly18.

As depicted, the sleeve16is disposed radially outwardly of the tool nose19. A radially inwardly facing surface of the sleeve16is sized and configured, at the distal end174of sleeve16, to sealingly engage the radially outwardly facing surface of the proximal portion194of tool nose19. A pair of O-rings22prevent the flow of fluid between the tool nose17and the sleeve16.

The proximal end164of sleeve16has a radially extending, axially proximally facing surface that abuts against a radially extending, axially distally facing surface234of circular stop ring23. The proximal end164of sleeve16also includes an axially extending, radially inwardly facing surface that engages the radially outwardly facing surface150of body14.

The distal end174of the sleeve is disposed radially outwardly of the tool nose19. The downstream end176of the passageway17terminates at radially extending passageways20that are formed in the enlarged diameter portion194of the tool noose19. The radial extending passageways20conduct the fluid radially inwardly toward the central, axially extending passageway202of the tool nose19which houses tool12. Fluid in the upstream cavity of the axial extending passageway202is then directed to the axially extending central fluid passageway122formed in the tool12, and ultimately discharged out the distal end of tool12to impact the cutting surface of the work piece (not shown) upon which the tool12is performing an operation.

As depicted, the annular ring groove15can align with two or more radially extending port holes20in the tool holder nose. The radially inwardly facing surface of the proximal portion194of the tool holder nose19is rigidly connected to the radially outwardly facing surface212of ball-spline shaft21. The ball-spline shaft is disposed coaxially with and distally of the linear actuator11. The radially extending, axially proximally facing surface of the ball spline shaft21engages and is placed next to a radially extending, axially distally facing surface111of the linear actuator11. This end engagement permits the linear actuator11to axially move the ball spline shaft21.

In some implementations, the junctions between the radially outwardly facing surface of the tool holder body14, the radially inwardly facing surface of outer sleeve16, and the radially outwardly facing surface of the tool nose12are sealed using O-rings22.

The radially inwardly facing surface232of a circular stop ring23is rigidly clamped to the radially outwardly facing surface150of tool holder body14to prevent axial movement of the outer housing and thereby fixedly axially position the outer body. The proximal end of linear actuator11is rigidly connected to the distal end tail cap24. The tail cap24also serves to seal the linear actuator11from fluid intrusion.

In some implementations, this connection between tail cap24and linear actuator11can be removable, nonrigid, flexible, and or intermittent. For example, the linear actuator11can be semi-rigidly or flexibly connected to the tail cap24through the use of a rubber boot enclosure. Electrical power and/or signal control wires25from an external source102connect to the linear actuator11by passing through an axially extending off-axis hole26located in the tail-cap24.

FIG. 1(b)shows a cross-sectional view of the portion depicted inFIG. 1(a)cut along lines A-A. This view depicts the centrally located linear actuator11that is received within, and is encircled by the generally cylindrically tubular body14. The body14, as depicted, has an annular array of axially extending, parallel passageways13that extend longitudinally through the body14. Other configurations may also be used for the passageways13. The outer sleeve16includes an axially extending, central passageway17(FIG. 1a) for interiorly receiving the distal portion of the body14. The slip ring23shown includes a central passageway that is defined by radially inwardly facing surface232for interiorly receiving the body14. The slip ring23is disposed relatively proximally of, and coaxially with the sleeve16.

FIG. 1{circle around (c)} shows a cross-sectional view taken along lines B-B inFIG. 1(a). This view again depicts the centrally located linear actuator11being interiorly received by the central passageway148of the body14. One should note the cylindrical space48between the radially outwardly facing surface of the linear actuator11and the radially inwardly facing surface of the body14.

The axial passageways13of body14are not shown due to an axial position of lines B-B, which lines are positioned distally of the distal terminus of passageway13. Rather, lines B-B are positioned to extend through the annular ring groove15. This annular ring groove15controls fluid radially outwardly from the distal or downstream terminus of passageways13to the upstream end of sleeve passageway17, which also comprises a series of annularly disposed, axially extending passageways17in the outer sleeve16.

Alternately, this annular ring groove15can take the form of a series of holes or grooves. In some other implementations, the series of annular holes17in the outer sleeve16can take other forms, such as large semi-cylindrical or quarter-cylindrical spaces.

FIG. 1(d)shows a cross-sectional view taken along lines C-C ofFIG. 1(a). The ball spline shaft21is centrally located within the device such that the axis A of the device passes through the axis of the shaft21. The ball-spline shaft21is interiorly received with the rotary ball-spline bearing assembly18. The rotary ball-spline bearing assembly18is interiorly received with a central passageway of the proximal portion of the body14. The body14is itself interiorly received within the outer sleeve16.

FIG. 1(d)shows the annular array of longitudinally extending passageways17of outer sleeve16that act as passageways for the high-pressure cutting fluid. These passageways17have their upstream terminus at radial passageway172, and their downstream terminus at radial passageway20.

FIG. 1(e)is a cross-sectional view taken along lines D-D ofFIG. 1(a).FIG. 1(e)shows the tool holder nose19while interiorly received by and disposed coaxially with sleeve16that extends along part of the proximal portion194of the tool nose19.

A pair of radially extending port hole passageways20fluidly couple the downstream terminus of passageways17with that portion of the tool receiving cavity202of the tool nose19that is disposed proximally and upstream of tool12and the axially extending fluid passageway122of cutting tool12. As shown inFIG. 1(a), the cutting tool12is then inserted into the central passageway202of the tool nose holder19. Thus, high-pressure fluid travels from the annular array of passageways17in the outer sleeve16, through the radially extending passageways20in the tool holder nose19, and finally axially distally through the central passageway122of cutting tool12and then onto the cutting surface of the work piece.

FIG. 1(f)depicts an alternate embodiment of the present invention wherein high-pressure fluid circulates directly through a central passageway272defined by a sleeve27that extends through a central axially extending passageway formed in the linear actuator274and spline shaft276and tool nose278. The fluid can flow from its upstream terminus282at the proximal end279of the tail cap286, through the passageway portion within the linear actuator274. Fluid then continues to flow axially distally in the passageway through the spline shaft276, through the passageway272portion within the tool nose278and into the cavity that comprises the upstream (proximal) end of the central axially extending tool receiving passageway288of the tool nose278. The fluid then continues its axial and distal flow path through the central passageway292of the tool294.

This path differs from the fluid path shown inFIGS. 1(a)-1(e)where the fluid flow path directs the cutting fluid radially outwardly of, and spatially separated from the linear actuator11.

The path of the fluid flow inFIG. 1(f)is depicted as block arrows running distally from the proximal end294of the tool assembly296to the distal end298of the tool assembly296. Tool296also includes a body portion302, a bearing assembly301, and an off axis passageway306for receiving power/control cable308.

This embodiment ofFIG. 1(f)would not need to make use of the outer sleeve16to isolate the high-pressure fluid around the linear actuator11as the fluid instead travels directly through an axial, central passageway272created in the linear actuator274. The fluid in this passageway272is isolated from the linear actuator274by sleeve27, thus preventing contamination or degradation of the linear actuator274. One such means of isolation is the use of the hollow tubular sleeve27and O-rings28to seal the fluid inside the tube27and linear actuator274.

Another alternate embodiment isolation means involves coating the passageway of the linear actuator274with an inert resilient coating or membrane. Alternatively, an embodiment might comprise the use of a series of several small actuators (not shown), controlled in unison and forming a ring around a hollow tube27instead of using a single actuator (e.g.274).

FIG. 2shows the rotating modulation tool holder assembly10installed in a fixed spindle configuration30where the rotating modulation tool holder assembly10is permanently installed in the rotating spindle31. The path of the fluid is shown as block arrows that commence as the fluid flows radially inwardly through fluid receiving port43, and then axially distally through an axially extending passageway in the stationary section38(b) and rotating section38(a) of rotary hydraulic coupling38.

The fluid then continues in its axially distal path through cavity342which is defined by the radially inwardly facing interior wall344. Passageway cavity342is also defined by the radially outwardly facing wall of insulated coupling35and flexible end cap adapter36. The fluid then continues to flow axially distally into the annular array of longitudinally extending passageways13that are formed in body14.

A rotary electrical connector32having a rotating male plug member32(a) and a stationary female plug member32(b) enables power and/or signal wires25from a stationary external source102to connect to mating wires33leading to the modulation tool holder assembly10through a cylindrical shaft34that extends through the axially extending central passageway of insulated coupling37, retainer42, linear bearing41, rotary coupling38and which terminates at its distal end in the insulated coupling35. The rotary electrical connector32(a),32(b) consists of a conductive male rotating section32(a) and a conductive female stationary section32(b).

The rotating section32(a) is affixed to the stationary section32(b). The stationary member32(b) is fixedly coupled to the proximal end of cylindrical insulated coupling37. The insulated coupling37includes an axially extending interior passageway whose distal end is sized and configured for receiving the proximal end of cylindrical shaft34. Cable33passes through the interior passageway372of insulated coupling37. The stationary section32(b) of the rotary electrical connector32is connected to the external power and/or control source102by cable25.

The electrical power and/or control wires33pass through the passageway of the cylindrical shaft34that is connected to the insulated coupling35that is coupled to the rotating modulation tool holder assembly10. Flexible insulated coupling35is coaxially coupled to a tail-cap adapter36. The rotary electrical connector32(a),32(b) is adapted to be coupled to the end of the hollow shaft34using an insulated coupling37.

High-pressure fluid can be passed through the modulation tool holder assembly10to the cutting tool12. A rotary hydraulic coupling assembly38, that includes a rotating section38(a) and stationary section38(b) provides a vehicle for coupling the stationary portion of the device30(that includes those components at and proximal of stationary frame39, with the rotating portion of tool10, that includes rotating coupling38(a) and components distal thereof. The rotating section38(a) of the rotary hydraulic coupling38is connected directly to the distal end of the axially extending passageway312of rotating machine spindle31. The stationary section38(b) of the rotary hydraulic coupling38can be connected directly to the stationary frame39of the machine tool.

The hollow cylindrical shaft34is sealed in the rotary hydraulic coupling38using a shaft seal40. A linear hearing41is disposed distally of the shaft seal40and supports the hollow shaft34. The shaft seal40and linear bearing41are pressed centrically into the axially extending central bore of the retainer42. High-pressure fluid is supplied to axially extending passageway386of the rotary hydraulic coupling assembly38through, the port connector43.

FIG. 3(a)andFIG. 3(b)show examples of modulation tool holder assembly installations50(a) (FIG. 3(a)),50(b) (FIG. 3(b)) where the cutting tools12are intermittently exchanged into a tool assembly holder such as a machine spindle51, and the modulation tool holder assembly10can be exchanged in and out of the machine. In these configurations the modulation tool holder assembly10can be removed and reinserted into the machine spindle51by installing the modulation tool holder assembly10into the axially extending central passageway522of a tool receiver or adapter52.

Additionally, in the embodiments ofFIGS. 3(a) and 3(b)high-pressure fluid is circulated through a central passageway in522in tool receiver52, that is aligned with, and coaxial with an axially extending passageway512in machine spindle51. Machine spindle51has an axially extending central passageway512that is coaxially aligned with, and disposed distally of the stationary section57(b) of rotary electrical connector57. The passageway522of adapter52includes a relatively reduced diameter proximal portion524and a relatively enlarged diameter distal portion526.

The distal portion526has a diameter sized for receiving the proximal end components, such as body14, and end cap24of the machine tool holder10.

The path of the fluid is depicted as block arrows running from the proximal end514of passageway514to the distal end206of passageway202of tool nose19. In the embodiment shown, the electrical conductors, (such as wires53for power and/or control signals) connect to the linear actuator11of the modulation tool holder assembly10through the tool receiver or adapter52to a secondary electrical connector54. The secondary electrical connector54engages a primary electrical connector55mounted to the rotating machine spindle51.

The rotating machine spindle51includes an axially extending, off axis passage56through which wires562can be extended from the primary electrical connector55to the rotating section57(a) of a rotary electrical connector or slip ring57located proximally of and coaxially with the proximal end516of the rotating machine spindle51. The rotary electrical connector57includes a rotating section57(a) and a stationary section57(b). Stationary section57(b) includes fluid passageways512for enabling fluid to pass from the area or fluid conduit disposed proximally of stationary section57(b) to the proximal portion524of the axially extending central passageway527. The stationary section57(b) receives power and signals from an external power and/or control source102.

The rotating section57(a) of the rotary electrical connector57is rigidly connected (e.g., clamped) directly onto the proximal end516of the machine spindle51. In an alternate embodiment, this connection between the electrical connector57(a) and spindle51can be flexible instead of rigid. For example, the rotating section57(a) can be installed into a rubber, plastic, or otherwise non-rigid fixture connected to the proximal end of the machine spindle51. The stationary section57(b) of the rotary electrical connector57is engaged by a rotation preventing anti-rotation fixture58held rigidly in the machine.

The power and signal wires53can pass from the external power and control source102through the fixed housing (not shown) to the stationary section57(b) of the rotary electrical connector57. Alternatively, for example inFIG. 3(a), the wires53from the linear actuator11can pass through the adapter directly to a rotary electrical connector or slip ring57mounted onto the distal end516tool adapter52.

As used in the above implementations examples, commercial rotary slip rings can accommodate a wide range of operation. However, in some cases, the available working space for integration in the machine tool may limit their implementation. An alternative to slip rings is the use of a small, liquid metal filled rotating electrical connector348(e.g., Mercotac®, Inc.) that can be coupled directly to the end of a hollow shaft34connected to the modulation tool holder assembly10providing a conduit for the electrical power and or signal control to the linear actuator11of the modulation tool holder assembly10(FIG. 2).

The hollow cylindrical shaft34may be connected to the rotating TriboMAM® assembly using a flexible motor coupling36to reduce angular or concentric misalignment over the length of the assembly. This enables the hollow shaft34to rotate simultaneously with the modulation tool holder assembly10that is held in the machine spindle51(e.g., collet, chucking device, tool clamping device, etc.).

The hollow shaft34can pass axially through the axially extending central passageway344of the rotating spindle31that the modulation tool holder assembly10in the machine tool. The electrical power and/or signal wires25leading from the modulation device's linear actuator11can be routed through the hollow shaft34and connect to a rotating electrical connector32(a), which is then mounted directly to the end of the hollow shaft34opposite from the modulation tool holder assembly10.

The rotating electrical connector32(a) can be a single channel or multi-channel contactor design. The rotating electrical connector32(a) enables electrical power to be passed directly from a stationary power source—such as a power supply or controller102to the modulation tool holder assembly10. Wires for electrical power and/or control signals25can alternatively be passed directly through the hollow shaft34to the modulation tool holder assembly10.

The wires25can then be connected to the linear actuator11of the modulation device and/or any related sensors used for monitoring or feedback control of the modulation device10. In addition to providing a novel solution for providing power or control signals to and from the modulation tool holder assembly10, the rotating electrical connector32(a) is very compact in size, has no moving parts, and enables relatively high rotational speeds, in comparison to the contacts in a slip ring system.

Further, additional provisions can be made for one or more sensors or sensor arrays. These sensors or sensor arrays can be located at various points on the assembly length. For example, sensors and sensor arrays can be positioned at the cutting tool12, the actuator11, the spindle31(or51), and/or the hollow shaft34, etc. Alternately, in some implementations the actuator can be a combination unit consisting of an actuator and a sensor array.

These sensor arrays can provide a variety of information including but not limited to sensing temperature, pressure, magnetic flux, sound, etc.

The sensor provided information can enable a variety of features in addition to those already provided and discussed above. These features include sensors for determining conditions, that enable the tool's operation to be altered to compensate for a variety of conditions. For example, the modulation rate of the tool may be altered to compensate for temperature, perceived acoustic resonance, tool wear, changes in spindle rotation speed, and/or unexpected changes in the object being cut (e.g., density, hardness, etc.). Further, power to the linear actuator11can be regulated based upon sensor provided data.

Upon such input or inputs to the sensors or sensor arrays, signals can be transmitted along the same or similar passageways used by the signal and control wires25,33(or53), and the sensors can signal the modulation controller102and/or the machine controller to vary specific parameters, including but not limited to, modulation frequency and/or amplitude; spindle and/or tool holder rotation speed; and/or fluid discharge rate. The external controller or controllers can then vary parameters based on the sensor outputs according to preset and/or automatic schedules.

Preferably, sensors are employed that provide alarm actuating outputs or that cause operation of the tool to cease or be changed if a certain parameter reaches a predetermined caution or danger level. Examples of such conditions include the temperature exceeding 10% of the expected output, spindle rotation rate 10% below expected output, etc. The triggering of an alarm by a sensor may indicate to the machine operator that a manual inspection be performed, which inspections may cause the operator to pause machining until an appropriate inspection is completed.

Along with the electrical power and/or signal control requirements for a rotating modulation tool holder assembly10, the assembly10must often be capable of delivering high-pressure cutting fluids to cutting tools (e.g., drills) installed in the modulation tool holder assembly10. Static fluid pressures of 30-300 bar or higher may be required to perform satisfactorily. The high-pressure fluid is typically delivered to the rotating machine spindle31through a rotary hydraulic union38(e.g., Deublin®, Inc and Ott®, Inc).

These rotating unions38components form the connection between the stationary proximal portion of device30, and the rotating distal portion of the device. The rotating hydraulic coupling38enables the flow of high-pressure fluids through a stationary connection38(b) that interfaces to the rotating spindle31. The rotary hydraulic union38also includes a rotating section38(a) connected directly to the distal end of the machine spindle31and a stationary section38(b) that is connected directly to a fixed position in the distal portion machine tool39. Examples of high pressure cutting fluids include liquids (e.g., oil-based, kerosene, alcohol, compressed gases, etc.); pastes/gels (e.g., fatty alcohols, wax, etc); aerosols/mists; and/or gases (e.g., carbon dioxide, nitrogen, oxygen, etc. These fluids can be supplied, as depicted, through a radially extending connector43that is coupled on the stationary section38(b) of the rotating hydraulic union38.

In other embodiments, the fluid can be supplied by one or more connectors or passages that introduce the fluid to the device30at positions, or to structures other than coupling43. These positions and structures may be either internal or external to the assembly. In some implementations, several fluid receiving structures can be employed for introducing a variety of a plurality of fluids to the assembly30.

Further, different connectors can be used, with the different connectors being designed for introducing different fluids depending on the needs of the cutting operation. For example, oil-based lubricants can be supplied through a first connector; compressed gases can be supplied for specific applications through a second connector, etc. Preferably, a valve is provided within the system so that the flow of these fluid supplies can be regulated as necessary by the operator and/or controller.

Referring again toFIG. 2, the present invention also introduces a novel modification to the rotary hydraulic union38that enables the hollow shaft34from the modulation device to pass directly through the longitudinal axis of the stationary section38(b) of the rotary union38for supplying the high-pressure fluid. This configuration, as depicted, utilizes a linear bearing sleeve41, such as a bronze bearing or miniature roller bearing—installed into a rotary coupling, here depicted as retainer42, to maintain the centric position of the hollow shaft34while supporting the rotary motion.

This retainer42and bearing sleeve41are simultaneously coupled with a rotary shaft seal40that prevents fluid leakage. Thus, high-pressure fluid flows from the fluid supply port connection43; into the stationary section of the rotary union38(b); through the rotating section of the rotary union38(a); around the hollow shaft34and linear actuator11, and through the cutting tool12to the cutting surface.

Thus, particular embodiments of the subject matter have been described.

Other embodiments are within the scope of the following claims. In some cases, the actions and structures recited in the claims can be performed in a different order and/or with different components and still achieve desirable results.