Patent Description:
<CIT> describes a device according to the preamble of claim <NUM> for use in a machining system.

The described invention relates generally to systems for machining metals and other materials and more specifically to a system for machining metals and other materials into which an ultrasonic machining module has been incorporated, wherein the ultrasonic machining module is compatible with a variety of existing machining systems, devices, and processes due to its vibration-isolating characteristics.

Machining, which is a collective term for drilling, milling, reaming, tapping, and turning, is an enabling technology that impacts virtually all aspects of manufacturing in the United States and elsewhere in the world. In a specific example, a milling machine is a machining tool used to machine solid materials. Milling machines are typically classified as either horizontal or vertical, which refers to the orientation of the main spindle. Both types range in size from small, bench-mounted devices to much larger machines suitable for industrial purposes. Unlike a drill press, which holds the workpiece stationary as the drill moves axially to penetrate the material, milling machines move the workpiece axially and radially against the rotating milling cutter, which cuts on its sides as well as its tip. Milling machines are used to perform a vast number of operations, from simple tasks (e.g., slot and keyway cutting, planing, drilling) to complex tasks (e.g., contouring, diesinking).

Cutting and drilling tools and accessories used with machining systems (including milling machines) are often referred to in the aggregate as "tooling". Milling machines often use CAT or HSK tooling. CAT tooling, sometimes called V-Flange tooling, is the oldest and probably most common type used in the United States. CAT tooling was invented by Caterpillar Inc. of Peoria, Illinois, to standardize the tooling used on Caterpillar machinery. HSK tooling, sometimes called "hollow shank tooling", is much more common in Europe where it was invented than it is in the United States. The holding mechanism for HSK tooling is placed within the hollow body of the tool and, as spindle speed increases, it expands, gripping the tool more tightly with increasing spindle speed.

Improving the machinability of certain materials is of significant interest to manufacturers of military equipment and certain commercial hardware, as well as to the builders of machine tools. More specifically, very advanced materials such as armor plates and composites are notoriously difficult to machine with standard systems and methods. High-speed systems and ultra-hard tool bits are used for such material, but provide only a marginal increase in tool life and productivity. Significant improvements in the machinability of materials have been achieved by implementing advanced technologies such as laser, waterjet, and EDM cutting. However, these processes are high in capital cost, limited in application, and differ too much to be used in standard machine shops. Also, the application of these processes is limited to certain types of cuts in the materials on which they are typically used.

Ultrasonic-assisted machining was developed in the United States in the <NUM>'s and was used for machining materials that were considered to be difficult to machine at the time. The more modem process of ultrasonic machining (UM) involves the application of high power ultrasonic vibrations to "traditional" machining processes (e.g., drilling, turning, milling) for improving overall performance in terms of faster drilling, effective drilling of hard materials, increased tool life, and increased accuracy. This is typically accomplished by using drill bits manufactured from high speed steel (HSS), carbide, cobalt, polycrystalline diamond composite, or other suitable materials affixed to a collet (e.g., shrink fit, compression, hydraulic, or mechanical) that is affixed to an ultrasonic (US) transmission line. In this context, UM is not the existing ultrasonic-based slurry drilling process (i.e., impact machining) used for cutting extremely hard materials such as glass, ceramics, quartz. Rather, this type of UM concerns methods for applying high power ultrasonics to drills, mills, reamers, taps, turning tools, and other tools that are used with modern machining systems.

Although the use of ultrasonics with modern machining systems provides significant and numerous benefits, there are certain technical challenges involved, not the least of which is the incorporation of ultrasonic energy into machining systems that were not originally designed to accommodate this type of energy output. Thus, there is an ongoing need for an ultrasonic machining module that is compatible with and that may be incorporated into existing machining systems without damaging or negatively impacting the performance of such systems.

The following provides a summary of certain exemplary embodiments of the present invention. This summary is not an extensive overview and is not intended to identify key or critical aspects or elements of the present invention or to delineate its scope.

In accordance with one aspect of the present invention, a first device for use in a machining system is defined in claim <NUM>.

Additional features and aspects of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the exemplary embodiments. As will be appreciated by the skilled artisan, further embodiments of the invention are possible without departing from the scope of the invention. Accordingly, the drawings and associated descriptions are to be regarded as illustrative and not restrictive in nature.

<FIG>, which are incorporated into and form a part of the specification, schematically illustrate one or more exemplary embodiments of the invention and, together with the general description given above and detailed description given below, serve to explain the principles of the invention, and wherein:.

Exemplary embodiments of the present invention are now described with reference to the Figures. Although the following detailed description contains many specifics for purposes of illustration, a person of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.

With reference to <FIG>, a first exemplary embodiment provides an ultrasonic machining module for use in a machining system, wherein the ultrasonic machining module includes: (a) an ultrasonic transducer, wherein the ultrasonic transducer is adapted to receive a tool bit, and wherein the ultrasonic transducer further comprises: (i) a front mass; (ii) a back mass; (iii) a plurality of piezoelectric ceramics positioned between the front mass and back mass; (iv) at least one electrical connector; and (v) a bolt passing through the front mass, back mass, and ceramics, wherein the bolt is operative to apply compressive force to the ceramics; and (b) a vibration-isolating housing adapted to be both compatible with a machining system and to receive the ultrasonic transducer therein. The housing further includes a spring-like feature formed radially therein above the front mass, wherein the spring-like feature further includes a curved and thinned section of the housing, and wherein the curved and thinned section of the housing is operative to permit flexion in the housing for isolating all vibrations generated by the ultrasonic transducer when the device is in operation except axial vibrations transmitted to the tool bit, thereby preventing unwanted vibrations from traveling backward or upward into the machining system and potentially causing damage to the system or other problems. This particular embodiment is disclosed in <CIT> (now <CIT>).

With reference to <FIG>, an exemplary embodiment of ultrasonic machining module <NUM> includes three basic components: tool holder <NUM>, housing <NUM>, and ultrasonic transducer assembly <NUM>. Tool holder <NUM> includes upper portion <NUM>, which further includes primary bore <NUM> formed therein for attaching machining module <NUM> to the main spindle (e.g., CAT <NUM>, <NUM> or HSK) of a machining system (not shown). Lower portion <NUM> of tool holder <NUM> includes a plurality of secondary bores <NUM> that cooperate with similar structures in housing <NUM> to mechanically couple tool holder <NUM> to housing <NUM> using connectors <NUM> (i.e., centering bolts). In some embodiments of the present invention, tool holder <NUM> is shrink-fit to housing <NUM> in addition to or instead of being bolted thereto.

Housing <NUM> includes a rigid cylindrical body <NUM> that further includes a centrally located aperture <NUM> that is adapted to receive tool holder <NUM>, and a bottom opening <NUM>, into which ultrasonic transducer assembly <NUM> is inserted. Circumferential electrical contacts <NUM> (i.e., slip rings) are positioned on the exterior of housing <NUM>. As will be appreciated by the skilled artisan, the use of other types of electrical contacts is possible. For example, a single contact <NUM> may be utilized or the contacts may extend through the spindle of the machining system, while still providing or maintaining the flow of cooling air through the spindle. The top or upper portion of housing <NUM> includes a plurality of apertures <NUM> that connect to a plurality of bores <NUM> that correspond to the placement of bores <NUM> in tool holder <NUM> when machining module <NUM> is assembled. A series of connectors <NUM> are inserted into bores <NUM> and <NUM> for the purpose of bolting tool holder <NUM> to housing <NUM>. A plurality of air outlets <NUM> is formed in housing <NUM>. As described in greater detail below, air outlets <NUM> cooperate with specific structures on ultrasonic transducer assembly <NUM> to cool machining module <NUM> when in use, thereby reducing or eliminating the need for any separate or external system or apparatus for cooling piezoelectric ceramics <NUM>.

Housing <NUM> also includes circumferential region <NUM>, which acts as a vibration isolating spring, and as such is characterized as a "spring-like structure". In the exemplary embodiment, region <NUM> includes a contoured and thinned section of the material from which housing <NUM> is manufactured. When machining module <NUM> is in use, region <NUM> permits a degree of flexion in housing <NUM>, thereby absorbing and/or isolating acoustic energy generated by ultrasonic transducer assembly <NUM> and preventing unwanted vibration from traveling backward or upward into the spindle or other mechanical components of the machining system. Axial vibration generated by ultrasonic transducer assembly <NUM> is not diminished by region <NUM>; therefore, torque is still delivered to the tool bit or other item that is attached to front mass <NUM> and that is being used to machine a workpiece. The term "tool bit" should be understood to mean drill bit or any other item that is attached to front mass <NUM>. Essentially, region <NUM> is operative to absorb and/or isolate most or all vibrational modes except the axial vibrations directed toward the workpiece.

Ultrasonic transducer assembly <NUM> includes back mass <NUM>, front mass <NUM>, and a plurality of piezoelectric ceramics <NUM> positioned between these two structures. A plurality of electrodes <NUM> are sandwiched between piezoelectric ceramics <NUM>, and bolt <NUM> passes through back mass <NUM>, ceramics <NUM>, electrodes <NUM> and a portion of front mass <NUM>. When tightened, bolt <NUM> is operative to apply compressive force to piezoelectric ceramics <NUM>. Although not shown in the Figures, a series of electrical lead wires are typically attached to at least one of the electrodes <NUM>. These wires exit the interior of housing <NUM> either through housing <NUM> or though tool holder <NUM> where they then connect to circumferential electrical contacts <NUM>. Brush contacts or other types of electrical contacts may be used to provide electricity to machining module <NUM>. Transducer assembly <NUM> typically operates at power levels ranging from <NUM> kW-<NUM> kW and amplitudes ranging from <NUM> to <NUM>.

In the exemplary embodiment of ultrasonic machining module <NUM> shown in <FIG>, ultrasonic transducer assembly <NUM> further includes a plurality of cooling members, fins or vanes <NUM> that are located circumferentially around front mass <NUM> just beneath a plurality of air inlets <NUM> that are also formed in front mass <NUM>. When ultrasonic machining module <NUM> rotates, vanes <NUM>, which simulate a compressor wheel, are operative to draw air upward and through air inlets <NUM>. Air then flows through the interior of housing <NUM> across ceramics <NUM> for cooling purposes, and exits housing <NUM> though air outlets <NUM>. As shown in the Figures, the front or bottom area of front mass <NUM> includes a tapered collet <NUM> that further includes bore <NUM>, which is adapted to receive a drill bit, milling tool, or other item. As will be appreciated by the skilled artisan, a drill bit or other item (not shown) may be attached to collet <NUM> using the process known as shrink-fitting. By heating the mass around bore <NUM> uniformly, it is possible to significantly expand the diameter of the bore. The shaft of a drill bit or other item is then inserted into the expanded bore. Upon cooling, the mass around the bore shrinks back to its original diameter and frictional forces create a highly effective joint. In an exemplary embodiment, the bottom edge of housing <NUM> is attached to the top portion of front mass <NUM> using a shrink-fit process for facilitating removal of case <NUM> for repairing ultrasonic machining module <NUM>. As will be appreciated by the skilled artisan, other means of attaching tooling items to front mass <NUM> and/or attaching housing <NUM> to transducer assembly <NUM> are possible and are compatible with the present invention.

Some or all of the metal components of ultrasonic machining module <NUM> are typically manufactured from A2 tool steel. Alternately, D2, SS, <NUM>, and/or <NUM>-M tool steel may be used. Regardless of the material used, front mass <NUM> and back mass <NUM> may both be manufactured from the same material as a means for reducing amplitude. In general terms, mixing of the mass of these components adjusts amplitude. In the exemplary embodiment shown in <FIG>, total module length is about <NUM> inches (<NUM>). However, the present embodiment is scalable and miniaturized variants of ultrasonic machining module <NUM> are compatible with medical and surgical systems and devices, among other applications.

With reference to <FIG>, this example provides additional structures (beyond circular geometric reliefs formed in the housing wall) that act as a flexural member. The present example provides various alternate acoustic isolation features which substantially eliminate vibrations being passed back into the machine spindle/structure from the ultrasonic system, or passed from the machine to the tool tip. The novel aspects of these embodiments include: (i) the use of various geometrical features to aid in the isolation of ultrasonic energy; (ii) the use of secondary materials to dampen mechanical vibrations from the case/housing; (iii) the design of an acoustic isolation feature which is sufficient for applying machining forces while flexing in a manner which eliminates the transmission of vibrations back into the machine spindle/structure; and (iv) the design and incorporation of specialty geometry to enhance secondary motion such as torsional excitations.

<FIG> is a cross-sectional side view of an ultrasonic machining module <NUM>, showing a first alternate housing component <NUM>, which is disposed between tool holder <NUM> and ultrasonic transducer assembly <NUM>. This embodiment isolates vibrations created by ultrasonic excitation within ultrasonic machining module <NUM> by using a thin-walled structure <NUM> which is intended to flex or vibrate along with the ultrasonic excitation. This embodiment includes a first rigid body <NUM> affixed to the nodal position of transducer front mass <NUM> to rigidly couple the two bodies, thereby transmitting acoustical energy. Moving upward, the walls of housing <NUM> are reduced in thickness from the nodal rigid body, which is then intended to flex or vibrate accordingly. The upper most portion of housing <NUM> then increases in thickness arriving at a second rigid mass <NUM>, which is integrated with conventional tool holder <NUM>. This approach rigidly supports ultrasonic machining module <NUM>, thereby isolating unwanted vibrations to housing <NUM>.

<FIG> is a cross-sectional side view of an ultrasonic machining module <NUM>, showing a second alternate housing component <NUM>, which is disposed between tool holder <NUM> and ultrasonic transducer assembly <NUM>. In this embodiment, housing <NUM> includes vibration isolating region <NUM>, wherein rather than employing circular or round features within the walls of housing <NUM>, triangular geometric reliefs have been added. Similarly, <FIG> is a cross-sectional side view of an ultrasonic machining module <NUM>, showing a third alternate housing component <NUM>, which is disposed between tool holder <NUM> and ultrasonic transducer assembly <NUM>. In this embodiment, housing <NUM> includes vibration isolating region <NUM>, wherein rather than employing circular or round features within the walls of housing <NUM>, rectangular geometric reliefs have been added.

<FIG> is a cross-sectional side view of an ultrasonic machining module <NUM>, showing a fourth alternate housing component <NUM>, which is disposed between tool holder <NUM> and ultrasonic transducer assembly <NUM>. This embodiment incorporates no discernable reliefs or isolation features into housing <NUM>, but rather modifies the walls of housing <NUM> to be a λ/<NUM> wavelength system in which the housing walls are put into resonance with ultrasonic machining module <NUM>. Arriving at the λ/<NUM> wavelength involves a predetermined wall length for housing <NUM>, which is based on operating frequency. For example, a <NUM> resonator would utilize a housing wall length of approximately <NUM> inches.

<FIG> is a side view of an ultrasonic machining module <NUM>, showing a fifth alternate housing component <NUM>, which is disposed between tool holder <NUM> and ultrasonic transducer assembly <NUM>. This embodiment provides a rigid housing <NUM> that includes vibration dampening features <NUM> incorporated directly therein. Vibration dampening features <NUM> are essentially cutouts formed in the walls of housing <NUM>, and these cutouts may be backfilled with vibration dampening materials such as, for example, rubber, elastomer, alloys such as tin or Inconel, and/or other suitable materials. Vibration dampening features <NUM> may be circles, squares, rectangles, triangles, ellipses, or combinations thereof, and a variety of other geometries are also possible.

<FIG> is a side view of an ultrasonic machining module <NUM>, showing a sixth alternate housing component <NUM>, which is disposed between tool holder <NUM> and ultrasonic transducer assembly <NUM>. This embodiment also includes cutouts or features <NUM> formed in housing <NUM> that have a specific geometry that prevents acoustical energy from potentially being transmitted back into the machine tool. In this embodiment, while the specific geometry does isolate vibrations, the cutouts also enhance the vibration produced at the tip of a tool being used with ultrasonic machining module <NUM>. For example, it is possible to increase the amount of torsional displacement that is present at the tool tip beyond what is produced by the longitudinal displacement when driven by an ultrasonic wave. This in turn creates a mixed mode device, which when driven by a longitudinal mode, longitudinal excitation flexes the cutouts and then drives the entire body in a torsional manner. An example of this is shown in <FIG>, wherein slot diameter, length, angle, and direction will dictate the amount of torsional displacement.

<FIG> are cross-sectional side views of ultrasonic machining module <NUM>, showing vibration isolating feature <NUM>, which includes flexible spring-like structure <NUM> located at the nodal position of transducer <NUM>, which is located beneath housing <NUM> and tool holder <NUM>. While spring-like structure <NUM> does exhibit flexion that is adequate for isolating unwanted vibration generated by transducer <NUM>, spring-like structure <NUM> does retain enough rigidity for withstanding axial and side loads when subjected to machining operations. In this embodiment, flexible spring-like structure <NUM> is capable of vibrating both axially and radially. However, under forces in excess of <NUM> pounds, ultrasonic machining module <NUM> must not be capable of deforming, moving, or being displaced by the resultant force. Furthermore, the system must not dampen the vibrations when subjected to said loads. The embodiments depicted by <FIG> are not encompassed by the appended claims.

<FIG> are cross-sectional side views of an ultrasonic machining module <NUM> in accordance with the present invention, wherein ultrasonic transducer assembly <NUM> includes precision geometry that acts as an alignment boss <NUM> that is positioned at nodal position <NUM> of front mass <NUM>. As with other embodiments disclosed herein, this embodiment of the present invention includes an ultrasonic transducer assembly <NUM> that is joined with tool holder <NUM> and housing <NUM>. This embodiment also includes specific geometric features for providing precision alignment of the tool axis, sealing of ultrasonic machining module <NUM>, and vibration control. This precise geometry also acts as an internal sealing system in which a tapered or conical flange <NUM>, which is formed in housing <NUM>, is stretched within its elastic limits over a tapered or conical alignment boss <NUM>, thereby creating a seal against horizontal base <NUM>, which is formed on ultrasonic transducer assembly <NUM>. A small groove <NUM> formed in horizontal base <NUM> acts as an O-ring groove for providing additional sealing. Alignment boss <NUM> is located specifically at the λ/<NUM> nodal position (the point of maximum radial displacement) in a λ/<NUM> resonator for preventing horizontal base <NUM> from driving in a shear, bending, and/or axial mode; thereby maintaining the vibration-isolating properties of housing <NUM> and region <NUM>.

Claim 1:
A device (<NUM>) for use in a machining system, comprising:
(a) an ultrasonic transducer assembly (<NUM>) having a known nodal position (<NUM>), wherein the ultrasonic transducer assembly (<NUM>) is adapted to receive a machining tool, and
(b) a vibration-isolating housing (<NUM>) adapted to be both compatible with a machining system and to receive the ultrasonic transducer assembly (<NUM>) therein, wherein the housing (<NUM>) further includes a circumferential region (<NUM>) with a contoured and thinned section from which the housing (<NUM>) is formed for isolating all vibrations generated by the ultrasonic transducer assembly (<NUM>) when the device (<NUM>) is in operation except axial vibrations transmitted to the machining tool, thereby preventing unwanted vibration from traveling backward or upward into the machining system;
characterized in that the device (<NUM>) further includes:
(a) a conical alignment boss (<NUM>) formed in the transducer (<NUM>) at the nodal position (<NUM>) thereof;
(b) a conical flange (<NUM>) formed in the housing (<NUM>), wherein the conical flange (<NUM>) is stretched within its elastic limits over the conical alignment boss (<NUM>) thereby sealing the housing (<NUM>) against a horizontal base (<NUM>) formed on the transducer (<NUM>); and
(c) a groove (<NUM>) formed in the horizontal base (<NUM>) on the transducer (<NUM>) for receiving an O-ring, wherein the O-ring provides additional sealing properties to the device (<NUM>).