Balancer

Abstract: A tool holder assembly 10 including a tool holder 12 having a balancer assembly 21 adapted to selectively provide improved unbalance compensation.

Description: 1. Field of the Invention This invention relates to a method and to an apparatus for balancing a spindle or other rotating machinery and, more particularly, to an improved tool holder including a balancer assembly portion which provides enhanced balancer capabilities over that provided by prior balancer assemblies. 2. Background of the Invention A typical machine tool assembly includes a rotating spindle or other type of movable member which is normally adapted to selectively and removable receive and/or to be removably but securely coupled to a tool holder The tool holder is itself adapted to removably and securely receive a tool in a manner which allows the tool to move in response to the movement of the spindle. As the tool moves it performs some desired operation upon some surface or body often referred to as a "workpiece". The machine tool assembly therefore normally includes the cooperative combination of the tool, the tool holder, and the rotating or moving spindle which form or "machine" the work piece into a "finished product" having a desired shape and configuration. Typically, these machine tool assemblies experience a certain amount of unbalance and associated unbalance induced vibrations caused by the unbalance created by the wear and tear experienced by the tool and/or by a failure or "looseness" in the coupling between the tool holder and the tool and/or between the tool holder and the spindle. These unbalance type vibrations oftentimes cause the tool to inaccurately perform the desired task (e.g. the desired cuts within the workpiece are not of a uniform and desired depth), significantly decrease the overall tool life, and cause the production of a finished product which must be discarded resulting in a concomitant and undesired waste of resources. Accordingly, it is highly desirable to maintain the tool, tool holder, and spindle in a state of relative balance, thereby increasing the overall working life of the tool, increasing the overall accuracy with which the tool performs its work, increasing the overall operating life of the balancer assembly and consistently creating finished products of a desired shape and size. The Applicants have previously discovered and have previously patented a new and useful balancer assembly using several rotors which are selectively moved by means of at least one electromagnetic signal which selectively emanates and/or is generated from a driver. This electromagnetic balancer assembly is described and claimed within United States Patent Number 5,757,662 (the '662 patent); filed on November 29, 1994; issued on May 26, 1998; and assigned to these Applicant's Assignee. While the balancer assembly described and claimed within the '662 patent provides for a highly desirable and highly efficient unbalance compensation, Applicants have recently discovered that this balancer assembly offers even improved and greater unbalance compensation performance if adapted for use upon and/or as an integral part of a tool holder, thereby providing a tool holder with an integrally formed balancer assembly and/or a balancer assembly removably placed upon the tool holder. In fact, Applicants have discovered that the placement of the balancer upon the tool holder provides for increased effectiveness of vibration control and balance since the balance compensating element is now positioned in relatively close proximity to the actual source of vibration (e.g. the tool and the tool holder). Moreover, Applicants have found that the placement of the balancer upon the tool holder provides for a more accurate overall balancing condition since the balance compensation is achieved very close to the unbalance condition. Heretobefore, prior unbalance compensators could not achieve these highly desirable results since these prior unbalance compensators were not capable of being adapted for placement upon the tool holders due to their size, geometric configuration, and/or their employed unbalance compensation methodology. Accordingly, it is a principal object of the present invention to provide a tool holder having balancer portion which is selectively adapted to provide desired and improved unbalance compensation for the tool, tool holder, and for the entire balancer assembly and which allows the amount of vibration to be accurately measured and which further improves the overall accuracy of the unbalance compensation which is selectively provided. US-A-5240358 discloses a method and apparatus for balancing tools, where the balancing is achieved by the movement of balancing objects between a containment member and cavities within a balance reception member. Summary of the Invention It is therefore a primary object of this invention to provide an improved method and apparatus for selectively and relatively quickly and efficiently balancing rotating machine apparatuses and other similar types of devices. It is another object of this invention to provide an improved method and an apparatus which corrects a relatively large amount of vibration which is caused by rotating unbalance. It is yet another object of the invention to provide an unbalance compensator which is adapted to be disposed upon and/or integrally formed within a machine tool holder and which is further adapted to selectively provide desired unbalance compensation. According to a first aspect of the present invention a tool holder of the type adapted for use upon a spindle is provided. According to this first aspect of the present invention, the tool holder includes a generally elongated body having a tool reception portion which is adapted to removably receive a tool and an opposed spindle portion which is adapted to removably attach to a spindle; and a balancer which is adapted to selectively balance the tool and tool holder, said balancer comprising first and second movable rotors and a driver adapted to selectively generate an electromagnetic field effective to cause said movable rotors to provide said unbalance compensation. According to yet another aspect of the present invention a method of unbalance compensation is provided. The method includes the steps of providing a tool holder; providing a tool; providing a balancer; placing said balancer upon said tool holder; rotating said tool holder; measuring an amount of unbalance of said tool holder; balancing said tool holder, thereby providing compensation for at least a portion of said measured amount of unbalance, said balancer comprising first and second movable rotors, the method comprising a step of providing a driver that selectively generates an electromagnetic field effective to cause said movable rotors to provide said unbalance compensation. Further objects, features, and advantages of the present invention will become apparent from a consideration of the following description and the following subjoined claims when taken in conjunction with the attached drawings. Brief Description of the Drawings Various advantages of the present invention will become apparent to those skilled in the art by reading the following specification and by reference to the following drawings. Figure 1 is a perspective partial block diagrammatic view of a tool holder assembly made in accordance with the teachings of the preferred embodiment of this invention; and Figure 2 is a perspective partial block diagrammatic view of a balancer assembly made in accordance with the teachings of the preferred embodiment of the invention. Detailed Description of the Invention Referring now to Figures I and 2, there is shown a tool holder balancer assembly 10 made in accordance with the teachings of the preferred embodiment of this invention. As shown, assembly 10 includes a conventional tool holder 12, such as and without limitation, those commercially available tool holders available from the Kennametal Corporation of Latrobe, Penrzsylvania (e.g. model KC100, see also WO-A-90/11862), having a generally elongated tubular body 14 with opposed end reception portions 16, 18 generally disposed along the longitudinal axis of symmetry 20 of the tool holder. Moreover, as shown best in Figure 2, it should further be apparent to those of ordinary skill in the art that portion 16 is adapted to be selectively inserted into and secured into spindle 100 by known techniques while portion 18 is adapted to selectively receive tool 102. Tool 102 is secured within portion 18 by known fastening techniques. It should be apparent to those of ordinary skill in the art that other types of tool holders, other than the one shown in Figure 1, may be utilized in accordance with the teachings of this invention. Additionally, in accordance with the teachings of the invention, the tool holder 12 includes a balancer assembly 21 which is substantially similar to the balancer assembly 110 shown and described within the '662 patent. For example, assembly 21 is shown as assembly 110 in Figure 1 of the '662 patent. Assembly 21 includes selectively movable rotors 22, 24 which respectively correspond to and are substantially identical to rotors 350 and 351 of the balancer assembly 110 described within the '662 patent and further includes pole plates 26, 28, and 30 which respectively correspond to and are substantially identical to pole plates 330, 331, and 332 of balancer assembly 110. As shown best in Figure 2, balancer assembly 21 further includes an electromagnetic field producing driver 32 which respectively corresponds to and is substantially identical to driver 120 described and shown in the '662 patent. Moreover, balancer assembly 10 includes a controller 34 which is substantially similar to controller 140 shown and described with respect to Figure 2 of the '662 patent. Importantly, controller 34 is physically and communicatively coupled to sensor assembly 33 having at least three Hall Effect type sensors substantially identical to sensors 2670, 2671, and 2672 of the '662 patent, to driver 32, and to a displacement, velocity, or acceleration transducer 38 which is substantially identical to transducer 2635 of the '662 patent which provides a signal indicative of the amount of vibration caused by unbalance. Sensor 38 and sensor assembly 33 physically and communicatively connect to controller 34 by use of the interface module 37 which comprises a substantially hollow and closed container in which the various wires emanating from the sensors and the controller are physically coupled. Controller 34 further includes all of the other components shown and described with respect to Figure 26 of the '662 patent including a microcomputer operating under stored program control which is substantially identical to microcomputer 2615 of the '662 patent. In operation, as is fully and completely described within '662 patent, the controller 34 senses vibration by receipt of a signal from transducer 38. If the sensed vibration is greater then some threshold value, controller 34 energizes and/or pulses the driver 32 to cause rotors 22 and/or 24 to move to a new and different position in order to counterbalance the unbalance. The new position, as is fully and completely explained within '662 patent, is selected after recognizing the current position of the rotors 22, 24 by use of the sensor assembly 33. In this operation, the driver 32 is placed in relative close proximity to the balancer 12 so that the unbalance compensation can be achieved during the operation of the tool 102 or in an "in process" manner. Alternatively, the driver 32 may be located and/or positioned away from the balancer and spindle and the balance is achieved by placement of the tool holder 12 in close proximity to the remote driver 32 by use of spindle 100. Applicants have found that the placement of the balancer assembly 21 upon the tool holder 12 provides for a more accurate and faster unbalance compensation then previously obtained. Importantly, it is believed that no prior "active" unbalance compensating assembly has ever been placed upon a tool holder and that the use of the balancer assembly 21 upon toolholder 12 allows for a more exact and precise unbalance correction in the manner and for the reasons previously discussed.

Claims: A method of unbalance compensation comprising the steps of: providing a tool holder (10); providing a tool (102); providing a balancer (21); placing said balancer (21) upon said tool holder; rotating said tool holder (10); measuring an amount of unbalance of said tool holder (10); balancing said tool holder (10), thereby providing compensation for at least a portion of said measured amount of unbalance, characterised in that said balancer (21) comprises first and second movable rotors (22, 24) and the method further including a step of providing a driver (32) that selectively generates an electromagnetic field effective to cause said movable rotors (22, 24) to provide said unbalance compensation. A tool holder (10) of the type adapted for use upon a spindle (100), said tool holder (10) comprising a generally elongated body (14) having a tool reception portion (18) which is adapted to removably receive a tool (102) and an opposed spindle reception portion (16) which is adapted to receive said spindle, and a balancer (21) which is adapted to automatically balance said tool, characterised in that said balancer (21) comprises first and second movable rotors (22, 24) and a driver (32) adapted to selectively generate an electromagnetic field effective to cause said movable rotors (22, 24) to provide said unbalance compensation. A tool holder (10) according to claim 2 wherein said balancer (21) comprises at least one rotor (22, 24) which is moveable with respect to the tool holder (10); and a driver (32) which is adapted to selectively move said rotor (22, 24). A tool holder (10) according to claim 2 or 3 further comprising a sensor adapted to determine an amount of unbalance associated with said tool. A tool holder according to any of claims 2 to 4 wherein the balancer (21) is adapted to automatically balance said tool (102) by use of electrical and/or electromagnetic energy.

Inventors: DYER STEPHEN WILLIAM, HACKETT BRIAN KENT, DYER, STEPHEN WILLIAM, HACKETT, BRIAN KENT
Applicants: BALADYNE CORP, BALADYNE CORPORATION
Application year: 1999
Main classification: G01M1
IPC codes: G01M1, B23Q11