# Patent

## Title
Air valve coupling method and apparatus

## 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.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
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
1. Field of the Invention
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.
2. Description of the Related Art
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.
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.
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.
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.
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
The present invention clears the sealing surfaces of two air valves prior to their coupling.
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.
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.
Another advantage of the present invention is that one valve assembly is extended by the removal of an opposing air pressure.
Another advantage of the present invention is that air is utilized to extend a portion of one valve assembly.



BRIEF DESCRIPTION OF THE DRAWINGS
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:
FIG. 1 is a perspective view of a machining center utilizing an embodiment of an air-coupling valve of the present invention;
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;
FIG. 3 is another view of the air coupling valve of FIG. 2 showing an air flow being supplied to the air turbine; and
FIG. 4 is a close-up view of the air-coupling valve of FIGS. 2 and 3 as it clears any debris therefrom.



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
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.
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.
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.
Second valve 30 includes a biased cup 46, 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.
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.
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.
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.
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.
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.

## Claims

1. An air valve system for use with a machining center having a machining head and an air driven machining tool connectable to the machining head, the air valve system, comprising:
a first portion associated with the machining head; and
a second portion associated with the air driven tool, said first portion and said second portion including a connection having a seal and contact surfaces therebetween and configured to have an airflow across said contact surfaces before the seal of said connection seals the contact surfaces together.

2. The air valve system of claim 1, wherein said first portion includes an extendable cup having an opening therein.

3. The air valve system of claim 2, wherein said first portion further includes a sealing post located in said opening, said sealing post being biased to seal said opening.

4. The air valve system of claim 3, wherein said second portion includes:
a second portion cup having an opening therein; and
a biasing device applying a biasing force on said second portion cup.

5. The air valve system of claim 4, wherein said second portion further includes a sealing post positioned to seal said opening in said second portion when said second portion cup is extended to engage said sealing post of said second portion.

6. The air valve system of claim 5, wherein said first portion is held in a retracted position by the application of pressurized air.

7. The air valve system of claim 6, wherein said first portion extends to engage said second portion by the removal of said pressurized air.

8. The air valve system of claim 7, wherein said sealing post of said first portion and said sealing post of said second portion contact each other prior to when said connection is sealed.

9. The air valve system of claim 8, wherein said sealing post of said first portion and said sealing post of said second portion each have complimentary centering features that engage each other to orient said sealing post of said first portion.