Abstract:
A machining system that includes an ultrasonic machining assembly, wherein the ultrasonic machining assembly further includes a machining tool; a collet adapted to receive the machining tool; and an ultrasonic transducer, wherein the ultrasonic transducer is operative to transmit acoustical vibrations to the machining tool; and a machining apparatus, wherein the machining apparatus is adapted to receive and secure the ultrasonic machining assembly, and wherein the machining apparatus is operative to transmit torque to the machining tool by applying rotary motion to the ultrasonic machining assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/329,355 filed on Apr. 29, 2010 and entitled “Ultrasonic Machining System” and U.S. Provisional Patent Application Ser. No. 61/333,483 filed on May 11, 2010 and entitled “Ultrasonic Machining System”, the disclosures of which are hereby incorporated by reference herein in their entirety and made part of the present U.S. utility patent application for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The described invention related generally to systems for machining materials and more specifically to a system for providing both longitudinal and rotary motion to a tool used for machining very hard materials. 
         [0003]    Machining, which is a collective term for drilling, milling, reaming, and turning, is an enabling technology that impacts virtually all aspects of manufacturing in the United States and elsewhere. With regard to a specific example, a milling machine is a machining tool used to machine solid materials, particularly metals. 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) 
         [0004]    Improving the machinability of certain materials is of significant interest to manufacturers of military equipment and commercial hardware, as well as to machine tool builders. More specifically, very advanced materials such as armor plates and composites are notoriously difficult to machine with standard methods. High-speed systems and ultra-hard tool bits are used for materials such as these, 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, their application is limited to certain types of cuts in materials. 
         [0005]    Ultrasonic-assisted machining was developed in the United States in the 1950&#39;s and was used for machining materials that were considered to be difficult to machine at the time. The more modern 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 high speed steel (HSS) drill bits affixed to a shrink fit collet that is bolted 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, and other tools that are used with modern machining systems. 
         [0006]    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 assembly that is compatible with and that may be incorporated into existing machining systems. 
       SUMMARY OF THE INVENTION 
       [0007]    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. 
         [0008]    In accordance with one aspect of the present invention, a machining system is provided. This machining system includes an ultrasonic machining assembly and a machining apparatus. The ultrasonic machining assembly further includes a machining tool; a collet adapted to receive the machining tool; and an ultrasonic transducer that is operative to transmit acoustical vibrations to the machining tool. The machining apparatus is adapted to receive the ultrasonic machining assembly and is operative to transmit torque to the machining tool by applying rotary motion to the ultrasonic machining assembly. 
         [0009]    In accordance with another aspect of the present invention, a machining system is also provided. This machining system includes an ultrasonic machining assembly and a machining apparatus. The ultrasonic machining assembly further includes a tool; a collet adapted to receive the tool; and a half wave ultrasonic transducer that is operative to transmit acoustical vibrations to the tool. The machining apparatus is adapted to receive the ultrasonic machining assembly and is operative to transmit torque to the tool by applying rotary motion to the ultrasonic machining assembly. An optional half wave extension is positioned between the collet and the ultrasonic transducer. 
         [0010]    In yet another aspect of this invention, a drilling system is provided. This drilling system includes an ultrasonic drilling assembly and a drilling apparatus. The ultrasonic drilling assembly further includes a drill bit; a collet adapted to receive the drill bit; and an ultrasonic transducer that is operative to transmit acoustical vibrations to the drill bit. The drilling apparatus is adapted to receive the ultrasonic drilling assembly and is operative to transmit torque to the drill bit by applying rotary motion to the ultrasonic drilling assembly. 
         [0011]    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 and spirit of the invention. Accordingly, the drawings and associated descriptions are to be regarded as illustrative and not restrictive in nature. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying drawings, 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: 
           [0013]      FIG. 1  is a cross-sectional side view of an exemplary embodiment of the ultrasonic machining/drilling assembly of the present invention; 
           [0014]      FIGS. 2   a - b  are an exploded side view and an exploded cross-sectional side view of the ultrasonic machining/drilling assembly of  FIG. 1 ; 
           [0015]      FIGS. 3   a - b  are an exploded side view and an exploded cross-sectional side view of the collet/mandrel component of the ultrasonic machining/drilling assembly of the present invention; and 
           [0016]      FIG. 4  is a side view of an exemplary ultrasonic machining/drilling assembly mounted within an exemplary machining apparatus. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    One or more 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. The present invention permits the integration of high power ultrasonics into conventional machine tools, thereby enhancing current industrial processes. This invention permits the machining industry to effectively harness the benefits of ultrasonic machining through a simplified design that uses common tools such as twist drills, mills, reamers, boring bars, and the like. This is accomplished through the use of a modified acoustic transmission line which acts as the machine&#39;s spindle combined with the ability to exert high axial force and torque while operating, for example, at 20-kHz and power levels up to 6-kW. This is compatible with high speed steel, carbide, and specialty coated cutting tools. For certain applications, this invention facilitates access to a drill head assembly, thus permitting ready exchange of twist drills or other tools or devices in a manner expected by tooling manufacturers and users. With reference now to the Figures, one or more specific embodiments of this invention in described in greater detail. 
         [0018]    As best shown in  FIGS. 1 and 2   a - b , an exemplary embodiment of the present invention configured for use with a twist drill (e.g. a Climax drill) or the like, includes ultrasonic machining assembly  10 . Ultrasonic machining assembly  10  further includes full-wave drill bit  10 , which includes tip  22 , body  24 , and base  26 ; collet  30 , which functions as both a collet and a mandrel; half-wave extension  60 ; and half-wave ultrasonic transducer  70 , all of which are inserted into and supported by drill head  90 , which is slidably mounted on support  94 . Drill head  90  rotates ultrasonic machining assembly  10  when the system is in use. Half-wave extension  60  includes first region  62  for receiving a set screw (not shown), an elongated body  64 , and a second region  66  for receiving a set screw (not shown). Ultrasonic transducer  70  includes front mass  72 , region  74  which is adapted to receive a set screw (not shown), rear mass  76 , housing  78 , and an electrical connector  80  for connecting the transducer electrodes (not shown) to a power source. A plurality of piezoelectric ceramics is positioned between front mass  72  and rear mass  76 . In this embodiment, ½-20 UNF set screws are used to connect half-wave extension  60  to both collet  30  and ultrasonic transducer  70 . Ultrasonic transducer  70  provides acoustic vibrational energy to ultrasonic machining assembly  10  when the system is in use. 
         [0019]    As best shown in  FIGS. 2   a - b  and  3   a - b , collet  30  includes upper shell portion  32 , the inner diameter of which defines upper chamber  34 . Upper chamber  34  is adapted to receive base  26  of drill bit  20 , which is secured therein using a shrink-fit process. By heating the mass around upper chamber  34  uniformly, it is possible to significantly expand the diameter of the chamber. Base  26  is then inserted into the expanded chamber. Upon cooling the mass around the bore shrinks back to its original diameter and frictional forces create a highly effective joint. Collet  30  further includes a rigid nodal point mounting ring  36  and lower shell portion  38 . Circumferential undercut  41  (see  FIG. 3   a ) is formed in shell wall  40  as are optional mounts  42  which, in the exemplary embodiment, are 10-32 holes adapted to receive a containment plate which affixes collet  30  to drill head  92  (see  FIG. 4 ), if desired. A slot type cut  43  engages a fixed key inside drill head  92  for transmitting torque from the motor driving drill head  92  to collet  30  once inserted into drill head  92 . By this means, torque is then transmitted to the cutting face of drill bit  20  or other machining tool. The inner diameter of shell wall  40  defines lower chamber  44 , which is adapted to receive one end of half-wave extension  60 . Cylindrical structure  46  extends into lower chamber  44  and includes region  50 , which is adapted to receive a set screw (not shown), as well as bore  48 , which extends through the center portion of collect  30 . Bore  48  is included so that when base  26  is shrink-fit into upper chamber  34 , it is unnecessary to overcome the compression of any air trapped in the bottom of chamber  34 . 
         [0020]    The design of collet  30  isolates all vibrations generated by ultrasonic transducer  70  except the axial vibrations transmitted to drill bit  20 ; therefore, drill head  92  and the machining system generally are protected from damage that ultrasonic vibrations could potentially cause should such vibrations be transmitted beyond collet  30 . More specifically, the relationship between the placement of rigid nodal point mounting ring  36 , the thickness of shell wall  40 , and the placement of circumferential undercut  41  results in what is essentially zero vibrational motion of collet  30  at the mounting position of ultrasonic machining assembly  10  within a machining system. Basically, this invention provides a rigid mount system that includes a clamping location that has been isolated from ultrasonic vibrations, yet is still capable of transmitting high torque to a machining tool. Additionally, changing out defective, damaged, or worn machining tools requires only the removal of the collet containing the machining tool, whereas prior practices required the complete disassembly of the stack for tool replacement. Accordingly, the present invention significantly reduces the time and effort needed for replacing tools and also results in dramatic improvements in tool life. 
         [0021]    While the present invention has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in certain detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to any of the specific details, representative devices and methods, and/or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s general inventive concept.