Abstract:
A machine tool and method provides integral cooling to the tool, by employing exhaust air from the drive motor. The exhaust air is suitably allowed to expand within the body of the tool, advantageously cooling the tool.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to machine tools, and more particularly to methods and apparatus for cooling machine tools. 
     When using machine tools, the tool will naturally generate heat when in operation. As the tools are designed to be more compact and lighter weight, generated heat becomes more of an issue. Thus, it becomes desirable to have some provision for cooling the tool, so that it may be operated for longer periods of time without having to stop to allow the device to cool. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, a machine tool, suitably pneumatically powered, uses exhaust air from the air motor to cool the machine tool. 
     Accordingly, it is an object of the present invention to provide an improved machine tool that is advantageously cooled by use of exhaust air from the driving motor. 
     It is a further object of the present invention to provide an improved method of cooling a machine tool using exhaust air from the tool&#39;s drive motor. 
     It is yet another object of the present invention to provide an improved machine tool cooling system. 
     It is another object of the invention to provide an improved portable machining assembly having enhanced cooling features. 
     The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a machine tool in accordance with the invention; 
     FIG. 2 is an exploded perspective view of the machine tool; 
     FIG. 3A is a perspective view of the beveling head employed with the machine tool; 
     FIG. 3B is a perspective view of the facing head employed with the machine tool; and 
     FIG. 4 is an exploded view of the facing head employed with the machine tool. 
    
    
     DETAILED DESCRIPTION 
     The system according to a preferred embodiment of the present invention comprises a portable machining assembly that employs exhaust air from the air motor driving the device to provide enhanced cooling of the device. 
     Referring to FIG. 1, a perspective view of a machine tool according to the invention, the tool comprises a main body  12  to which other components are mounted. An air motor  14  extends to one side of the main body, with an air cooling tube  15  extending between the exhaust port of the motor and the main body. The air motor receives input driving air from a pressurized air supply (not show) via a swivel fitting  16 , valve ball  18  and fitting pipe  20 , which communicates the air supply into the motor for driving thereof. 
     A draw rod  21  carrying a mandrel  22  extends from the main body  12 , and includes extensible ramps  24  thereon, suitably 3 such ramps being provided, spaced radially 120 degrees apart around the mandrel. A beveling head  26  is removably mountable to the main body and carries plural tool mounting sites thereon to receive tooling bits. 
     On the side of the main body opposite where the air cooling tube  15  attaches, an air muffler is provided, in communication with the interior of the main body via a fitting elbow  30 . 
     At the end of the draw rod opposite the mandrel and ramps, on the opposing side of the main body, a draw rod knob  32  is provided, rotatable to extend or retract the ramps  24  for mounting the device to a work piece location. 
     Mounted atop the main body, near the side carrying the beveling head, is a feed lever  34  which cooperates with feed rate adjustment screw  36  (suitably extending through the main body from the opposite side, so as to adjustably engage the feed lever. 
     Feed handles  38  are mounted to a nut barrel  40 , the nut barrel being normal to the longitudinal axis of the mandrel/draw rod. 
     In operation, the device is mounted to a work piece by insertion of the mandrel into an opening within the work piece, and clockwise rotation of the draw rod knob  32 , which causes the ramps  24  to extend outwardly, radially, so as to engage the interior surface of the opening in the workpiece. To assist in providing a tightened engagement of the ramps with the workpiece, the draw rod knob suitably has a hexagonal nut like shape at one end that cooperates with a correspondingly shaped recess in the nut barrel. The knob is slightly biased outwardly so that in absence of pressing by an operator, the knob is not engaged with the opening in the nut barrel. Thus, the knob may be depressed so as to engage with the opening in the barrel, whereby the feed handles may be used to assist in tightening the draw rod so as to thereby tighten the engagement with the workpiece. 
     Prior to mounting the device to the work piece, the beveling head would be suitably mounted to the main body. Cutting bits are mounted to the beveling head as desired to accomplish the particular objective. 
     By rotation of the feed handles and the attached nut barrel, the main body will translate along the mandrel, so as to move closer to the work piece for initial positioning prior to applying power. 
     When a beveling or facing operation is to begin, the air supply is attached to the swivel fitting, and the ball valve is then opened (by operation of handle  19 ) to supply air to the motor. The drive power of the motor causes the beveling head to rotate, and, depending on the adjustment of the feed screw  36 , the feed lever  34  will be engaged by the rotating beveling head, so as to incrementally feed the main body along the mandrel as the beveling head rotates. 
     While the motor is operating, exhaust air therefrom will exit the motor, into cooling air tube  15 . The configuration of the tube carries the exhaust air from the motor to a connection at the main body  12 , providing the air into the interior within the body. On entering the interior of the body  12 , the air provides cooling to the device. The interior of the body, which may also be referred to as a gear box, suitably provides for expansion of the air, which furthers the cooling. At the opposite side of the main body from where the cooling air enters, it exits the main body through muffler  28 . In the preferred embodiment which is shown, the muffler is mounted via a fitting elbow, substantially opposite to the side of the main body where the exhaust air from the motor s introduced. Other configurations may be employed, positioning the muffler at different locations. 
     The illustrated beveling head  26  in FIG. 1, FIG.  2  and FIG. 3A is for performing a beveling operation, and suitably mounts to the main body via a bayonet fitting. Alternatively, a facing head  26 ′, illustrated in FIG.  3 B and FIG. 4, may be mounted so as to provide facing operations. The facing head  26 ′ suitably feeds the cutting bit radially outwardly (or inwardly). 
     Components of the facing head comprise rack feed  42 , lever feed  44  with knob  46 . An axial feed pinion  48  cooperates with the rack  42  so as to provide feeding. Dowel pins  50  enable engagement with the feed body. A tool holder  52  translates along the facing head via its engagement with the rack. Rotation of the pinion to feed the rack is accomplished via roller clutch bearings  54  and feed direction bushings  56 . 
     Thus, as the facing head rotates, operation of the components therewithin result in the controlled rotation of pinion  48  which cooperates with the rack to feed the cutting bit radially as indicated by arrow  58 . 
     Thus, the air which powers the driving motor suitably also provides cooling to the overall device, which enables a more compact configuration to the device and enables the device to operate longer without overheating. Accordingly, in addition to the facing and cutting features, an advantage to the device is that it is integrally cooled using the exhaust from the air powering the device. The exhaust air is piped back into the main body or gear box of the device, where the air expands somewhat, cooling the device. Thus, a relatively compact configuration can be employed without over heating. 
     While a preferred embodiment of the present invention has been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the invention in its broader aspects. The appended claims are therefore intended to cover all such changes and modifications as fall within the true spirit and scope of the invention.