Patent Publication Number: US-2020276654-A1

Title: Modular Tool Holder For Ultrasonic Machining

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to relates to modular tool holders and more particularly to a modular tool holder for ultrasonic machining. 
     2. Description of Related Art 
     Conventional ultrasonic machining (USM) involves mounting an electronic oscillator on a spindle. The oscillator produces an alternating current oscillating at a high frequency in the ultrasonic range. A transducer converts the oscillating current to a mechanical vibration which is transmitted to a tool held by a holder. USM can remove material from the surface of a part through high frequency, low amplitude vibrations of the tool against the material surface in the presence of fine abrasive particles. USM is typically used on brittle materials as well as materials with a high hardness due to the microcracking mechanics. 
     The tool travels vertically or orthogonal to the surface of the part. The fine abrasive grains are mixed with water to form slurry that is distributed across the part and the tip of the tool. Typical grain sizes of the abrasive material are very small so as to produce smoother surface finishes. 
     In an ultrasonic machining process, the oscillator produces an alternating current oscillating at a high frequency in the ultrasonic range. The transducer converts the oscillating current to a mechanical vibration which is transmitted to the tool held by the holder. However, components may collide one another resulting in undesired vibration which may interfere with the high frequency vibration. An in turn, it may adversely affect precision of the workpiece. 
     Elongated tool holders are disclosed by U.S. Pat. Nos. 1,502,528, 2,716,030 and 8,821,084. For high length to diameter (L/D) ratio, the precision of the workpiece may be very low or even be impossible of being machined due to rigidity of the material of the tool holder. These are problems encountered by the conventional ultrasonic machines. Further, in USM the path of transmitting vibration may be very long. And in turn, it may cause strong interference to undesirably vibrate the tool holder. Furthermore, the maximum amplitude of the vibration frequencies cannot be controlled to focus on the tip of the tool. And in turn, the cutting effect is adversely affected. Also, smoothness and quality of the workpiece are low. To the worse, the ultrasonic machines are damaged. 
     Thus, the need for improvement still exists. 
     SUMMARY OF THE INVENTION 
     It is therefore one object of the invention to provide a modular tool holder for ultrasonic machining wherein an oscillator for producing ultrasonic vibration is disposed in the tool mounting member so that the path for transmitting the vibration of high frequency can be greatly decreased, undesired vibration to the tool holder by the high frequency vibration can be eliminated, and smoothness and quality of the workpiece are improved. 
     It is another object of the invention to provide a modular tool holder for ultrasonic machining wherein the inadequate rigidity of the material of the conventional tool holder having a high L/D ratio is improved, and the high L/D ratio is significantly decreased. As shown in  FIG. 2 , the length to diameter ratio before the installation of the oscillator for producing ultrasonic vibration labeled L 1 /D is decreased to L/D after the installation of the oscillator for producing ultrasonic vibration. Further, the provision of at least one sleeve can lengthen the tool holder while the L/D is fixed irrespective of the value of L 1 . 
     It is still another object of the invention to provide a modular tool holder for ultrasonic machining wherein the length of the tool holder can be changed by providing at least one sleeve interconnecting a connector and a tool mounting member. 
     It is a further object of the invention to provide a modular tool holder for ultrasonic machining by the provision of a releasable chuck which can be replaced such as Shrink-fit holder or ER collet chuck or milling chuck depending on applications so as to avoid interference and having an optimum rigidity. 
     For achieving above an other objects of the invention, there is provided a modular tool holder for ultrasonic machining used in a machine which supplies power via a spindle, comprising a connector received in the spindle; a conductive ring disposed on the connector and electrically connected to the spindle so as that power is configured to supply to the modular tool holder; a tool mounting member including an axial hole; an oscillator for producing ultrasonic vibration disposed in the tool mounting member, the oscillator for producing ultrasonic vibration electrically connected to the conductive ring so that power supplied to the oscillator for producing ultrasonic vibration is configured to produce ultrasonic vibration of high frequency; and a chuck releasably secured to an end of the axial hole. 
     Preferably, the tool mounting member further comprises further comprises a flexible chuck having the axial hole of the tool mounting member disposed therein, the flexible chuck including a plurality of lengthwise parallel slits each having an open end, and a plurality of latches each disposed between two adjacent ones of the slits; and a fastener disposed on one end of the flexible chuck so that a force exerted upon the flexible chuck is configured to flexibly deform the latches to fasten the tool in the flexible chuck. 
     Preferably, there is further provided an axial channel in the connector communicating with inside of the tool mounting member, and a wire having one end electrically connected to the oscillator and the other end electrically connected to the conductive ring by passing through the axial channel. 
     Preferably, there is further provided at least one sleeve interconnecting the connector and the tool mounting member. 
     Preferably, each sleeve includes a projection at one end and a receptacle at the other end so that the at least one sleeve is configured to complimentarily attach to both the connector and the tool mounting member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention, as well as its many advantages, may be further understood by the following detailed description and drawings in which: 
         FIG. 1  is a longitudinal sectional view of a modular tool holder for ultrasonic machining according to the invention; and 
         FIG. 2  is a detailed view of the area in right side of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 and 2 , a modular tool holder for ultrasonic machining according to the invention is used in a machine which supplies power via a spindle (not shown). The modular tool holder for ultrasonic machining comprises a connector  10  received in the spindle, a conductive ring  11  disposed on the connector  10  and electrically connected to the spindle so that power may be supplied to the modular tool holder; a substantially cylindrical tool mounting member  20  including an axial hole  21  for fastening a portion of a tool (e.g., tool handle but not shown); and an oscillator  30  for producing ultrasonic vibration disposed in the tool mounting member  20 , the oscillator  30  for producing ultrasonic vibration electrically connected to the conductive ring  11  so that power may be supplied to the oscillator  30  for producing ultrasonic vibration. The produced vibration of high frequency is transmitted to the tool via the axial hole  21 . The tool mounting member  20  further comprises a chuck  22  having the axial hole  21  formed therein. As a result, the path for transmitting the vibration of high frequency can be greatly decreased. 
     The connector  10  has a stepped-diameter outer surface  15  which is configured to receive in the spindle of a machine. Thus, the modular tool holder may be aligned with the spindle to be secured together. The connector  10  is designed to allow the modular tool holder to be used in an automatic tool changing system. 
     The tool mounting member  20  further comprises a fastener  23  disposed on one end of the chuck  22  so that the chuck  22  can be releasably secured to one end of the axial hole  21 . The chuck  22  can be replaced with a rigid shank or an ER elastic shank depending on applications, especially in a multi-spindle machine (e.g., five-spindle machine) for avoiding interference and having an optimum rigidity. The fastening of the chuck  22  using the fastener  23  is one of a plurality of fastening methods. Those skilled in the art may be aware of other fastening methods. 
     In a preferred embodiment of the invention, there is further provided an axial channel  12  in the connector  10  communicating with inside of the tool mounting member  20 . A wire  13  having one end electrically connected to the oscillator  30  in the tool mounting member  20  and the other end electrically connected to the conductive ring  11  by passing through the channel  12 . A non-contact conductive connection (e.g., electromagnetic induction) can be implemented between the conductive ring  11  and the spindle of the machine. Alternatively, a two-terminal conductive contact between the conductive ring  11  and the spindle of the machine can be implemented. As a result, power is supplied to the conductive ring  11  which is served as a carbon brush. 
     In another preferred embodiment of the invention, there is further provided a plurality of (e.g., two) sleeves  40  disposed between the connector  10  and the tool mounting member  20 . Each sleeve  40  includes a projection  41  at one end and a receptacle  42  at the other end so that the projection  41  of one sleeve  40  can be complimentarily attached to the receptacle  42  of the other sleeve  40 . A protrusion  14  is provided at one end of the connector  10  for complimentarily attaching to the receptacle  42  of one sleeve  40 , and a cavity  26  is provided at the other end of the tool mounting member  20  for complimentarily attaching to the projection  41  of the other sleeve  40 . As a result, the connector  10 , the sleeves  40  and the tool mounting member  20  are secured together. The number of the sleeves  40  can be increased or decreased depending applications. Thus, the length of the tool holder can be adjusted. 
     It is envisaged by the modular tool holder for ultrasonic machining of the invention that the oscillator for producing ultrasonic vibration is disposed in the tool mounting member so that the path for transmitting the vibration of high frequency can be greatly decreased. Further, undesired vibration to the modular tool holder by the high frequency vibration may be eliminated. Furthermore, the inadequate rigidity of the material of the conventional modular tool holder having a high L/D ratio is improved. In addition, smoothness and quality of the workpiece are improved. Additionally, the provision of the sleeves may lengthen the modular tool holder if such need arises. In addition, the chuck can be replaced with a rigid shank or an ER elastic shank depending on applications. 
     Many changes and modifications in the above described embodiment of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, to promote the progress in science and the useful arts, the invention is disclosed and is intended to be limited only by the scope of the appended claims.