Abstract:
A machining center including a machining head, a tool changer, an air driven tool and an air valve system. The air driven tool is connectable to the machine head by action of the tool changer. The air valve system has a first portion associated with the machining head and a second portion associated with the air driven tool. The first portion and the second portion include a connection therebetween having an airflow across the connection before the connection seals.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This is a non-provisional application based upon U.S. provisional patent application Ser. No. 60/680,161, entitled “AIR TURBINE COUPLER”, filed May 12, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to the coupling of an air valve assembly, and, more particularly, to coupling an air valve assembly of a machining center.  
         [0004]     2. Description of the Related Art  
         [0005]     It is known to provide a spindle unit for a machine tool in which the tool holding end of the spindle has a tapered socket in its nose to receive and hold a tool holder provided with an adapter. The adapter may be engaged with finger hooks carried by a drawbar so that the finger hooks are engaged and the drawbar is pulled inwardly by a spring mechanism of the tool holder to hold the tool. To release the tool holder for removal from the spindle it is often necessary to reverse the operation and push the drawbar inwardly a substantial distance against the force of the spring.  
         [0006]     Tool changing centers use adapters to provide a uniform mounting mechanism to the spindle of a machining center so that individual tools may be mounted in the adapters for automatic insertion into the machine center spindle.  
         [0007]     It is also known to provide air turbines that connect to an air delivery system of the machining center to provide a high-speed rotation of a cutting tool, which may exceed the speed available from the spindle that is mechanically driven.  
         [0008]     A problem with the air coupling devices is that it is difficult to keep them clean and to ensure that no debris enters the air turbine.  
         [0009]     What is needed in the art is a simple cost effective way of removing debris from the coupling devices of an air valve.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention clears the sealing surfaces of two air valves prior to their coupling.  
         [0011]     The invention comprises, in one form thereof, a machining center including a machining head, a tool changer, an air driven tool and an air valve system. The air driven tool is connectable to the machine head by action of the tool changer. The air valve system has a first portion associated with the machining head and a second portion associated with the air driven tool. The first portion and the second portion include a connection therebetween having an airflow across the connection before the connection seals.  
         [0012]     An advantage of the present invention is that the flow of air is utilized to clean the valve prior to an engaging into a sealed relationship.  
         [0013]     Another advantage of the present invention is that one valve assembly is extended by the removal of an opposing air pressure.  
         [0014]     Another advantage of the present invention is that air is utilized to extend a portion of one valve assembly. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiments of the invention taken in conjunction with the accompanying drawings, wherein:  
         [0016]      FIG. 1  is a perspective view of a machining center utilizing an embodiment of an air-coupling valve of the present invention;  
         [0017]      FIG. 2  is a partially cross-sectioned view of an embodiment of an air-coupling valve of the present invention used in the machining center of  FIG. 1 ;  
         [0018]      FIG. 3  is another view of the air coupling valve of  FIG. 2  showing an air flow being supplied to the air turbine; and  
         [0019]      FIG. 4  is a close-up view of the air-coupling valve of  FIGS. 2 and 3  as it clears any debris therefrom. 
     
    
       [0020]     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Referring now to the drawings, and more particularly to  FIG. 1 , there is shown a machining center  10  having a machining head  12 , a tool changer  14 , tools  16  and an air driven tool  18 . Machining center  10  is under programmable control of a controller, not shown, that operates the relative position of an X-Y table, the spindle operation is in a Z direction. The spindle of machine head  12  receives tools  16  and  18 , which are shaped to a uniform adaptive feature so that they can be readily inserted into the spindle of machine head  12 . Tool changer  14  removes tools from the spindle and picks up tools  16  or  18  from a tool storage device. Air driven tool  18  is substantially similar to tool  16  except that air driven tool  18  has a valve system attached thereto. Machining center  10  is programmed to locate a cutting edge of a tool  16  or  18  in an appropriate position for cutting material mounted on the X-Y table.  
         [0022]     Now, additionally referring to  FIGS. 2-4  air driven tool  18  includes a coupling spindle  20 , a chuck  22 , an air turbine  24  and part of a valve system  26 . Coupling spindle  20  is a standard shape to fit the spindle of machine head  12 . A chucking device  22  is provided to mount cutting tools thereto. Valve system  26  includes a first portion  28  and a second portion  30 . First portion  28  is generally related to machine head  12  while second portion  30  is connected to air driven tool  18 . First portion  28  and second portion  30  can individually be considered valves  28  and  30  since each serve to close airflow openings when air driven tool  18  is not in position with machine head  12 .  
         [0023]     First valve  28  includes an extendable cup  32 , a seat  34 , a sealing post  36 , a spring  38  and O-rings  40 . Extendable cup  32  has O-rings  40  along the side and along a sealing surface to contain air pressure and also provide a bearing surface for the movement of extendable cup  32 . An air flow  42  serves as a retracting air flow  42  to hold extendable cup  32  in a retracted position, as shown in  FIG. 2 . Retracting airflow  42  works against the biasing force of spring  38  in holding extendable cup  32  in the retracted position. Seat  34  contacts a portion of sealing post  36  due to the biasing effect of spring  38 . This prevents the flow of air between sealing post  38  and seat  34 . Sealing post  36  has a centering feature  44  that interacts with a portion of second valve  30  to keep sealing post  36  centered as it is moved away from seat  34 .  
         [0024]     Second valve  30  includes a biased cup  36 , O-rings  48 , a spring  50  and a sealing post  52  having a centering feature  54 . Second valve  30  remains sealed as long as the biasing force from spring  50  keeps cup  46  in position against a beveled surface of sealing post  52 . O-ring  48  provides a sealing and bearing surface for the movement of biased cup  46  when extendable cup  32  encounters it.  
         [0025]     As can be seen in  FIG. 3  when retracting air flow  42  is removed and air pressure is provided to the back side of extendable cup  32 , cup  32  engages biased cup  46  allowing an air flow  58  to pass from an air source to an air plenum that is directed to air turbine  24 . The controller of machining center  10  includes air control valves that can remove the supply of air flow  58  and can supply a retracting air flow  42  to thereby disengage first valve  28  from second valve  30 .  
         [0026]     Prior to full engagement of valve system  26 , sealing post  36  contacts sealing post  52  allowing a cleansing air flow  56  to move across the sealing surface between an o-ring  40  and an outer surface of biased cup  46 . Although airflow  56  is schematically shown on one side, for the sake of clarity, it can easily be understood that the airflow is uniformly distributed around the sealing surface of cups  32  and  46 . This is assisted by centering features  44  and  54  respectively of sealing posts  36  and  52 , which keeps sealing post  36  centered in the opening of cup  32 . Airflow  56  advantageously removes debris that may be present on the surfaces of cups  32  and  46  prior to their full engagement as shown in  FIG. 3 . The rapidity of the encounter between cups  32  and  46  can be controlled by the amount of air pressure being supplied by way of air flow  56  and by additional springs along the sides of extendable cup  32 , which are not shown. Air pressure supplied to the back side of extendable cup  32  causes it to fully engage biased cup  46  by driving spring  50  into a more compressed state and allowing air to pass by way of air flow  58  to air turbine  24 .  
         [0027]     Reversing the steps, when it is time to disengage air driven tool  18  from machine head  12 , includes removing air flow  58  and supplying retracting air flow  42  to cause extendable cup  32  to retract to the position as shown in  FIG. 2 . When first valve  28  is fully retracted tool changer  14  may engage air driven tool  18  and remove it from machine head  12 . The actual control sequences of the machining tool language are known and are not discussed herein.  
         [0028]     Advantageously, the present invention allows for an automatic coupling that pre-cleans the sealing surface by a short burst of air prior to engaging and opening both valves. Positive airflow is ensured since the airflow must be present to cause the movement of the extendable cup. Another advantage of the present invention is that both valves automatically seal for the removal of the tool from the machine head.  
         [0029]     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.