Abstract:
The invention refers to a motor spindle for a machine tool which includes a tool clamping system configured to automatically clamp and release an adjustable tool, a control rod arranged within the tool clamping system, and a setting unit arranged at a B side of the motor spindle which is configured to adjust an adjustable tool via the control rod.

Description:
PRIORITY CLAIM 
       [0001]    This application claims benefit of priority of German application no. 102013208027.1 titled “Method and Apparatus for Adjusting Adjustable Tools Clamped on a Motor Spindle of a Machine Tool”, filed May 2, 2013, and whose inventor is Albert Hofmann. 
       INCORPORATED BY REFERENCE 
       [0002]    German application no. 102013208027.1 titled “Method and Apparatus for Adjusting Adjustable Tools Clamped on a Motor Spindle of a Machine Tool”, filed May 2, 2013, and whose inventor is Albert Hofmann, is hereby incorporated by reference in its entirety as though fully and completely set forth herein. 
       TECHNICAL FIELD 
       [0003]    The present invention refers to an apparatus and a method for adjusting adjustable tools clamped on a motor spindle of a machine tool. 
       DESCRIPTION OF THE RELATED ART 
       [0004]    Nowadays, high requirements are put on the profitability and the productivity of production plants. Machine tools are key elements in many production plants. Modern machine tools often have motor spindles. A motor spindle is a shaft directly driven by an electric motor which has an integrated tool interface. 
         [0005]    In order to fulfil the challenges in an automated flexible production with respect to productivity automatic tool clamping systems are already used since some time. Examples of automatic clamping systems are described in the European patent EP 0 339 321 B1 and in the published patent application DE 10 2005 008 892 A1. The patent DE 10 2010 009 664 B4 discloses a signal processing unit which allows to monitor a motor spindle and with which in particular a measure for a deviation of the motor spindle and/or its bearing from a target state can be determined. 
         [0006]    For more and more processing steps it is necessary to cool and to lubricate the tool, in order to secure the quality (dimensional accuracy, surface quality, durability, etc.) of the processing process. This is best secured in that the respective tools have fine bores through which the coolant and lubricant is directly provided at the operating place. 
         [0007]    Typically, the tools as well as the tool cutting edges are simultaneously cleaned from chips by the cooling means. Moreover, automatic clamping systems have a separate supply for cleaning air in order to keep the tool holder at the spindle side clean during a tool exchange. 
         [0008]    For fine processing processes and/or special processing processes, as for example recesses, adjustable or actuating tools have to be used. For adjustable tools, the tool cutting edges can be extended and retracted in a defined manner. For presently available adjustable tools for fine processing processes the actuating adjustment is often directly build into the tool. For example, the patent EP 1 169 154 B1 discloses the piezo-electric adjustment element arranged in tool for very fine processing for setting a cutting element. The patent DE 199 25 193 B4 describes a holding mechanism to hold a piezo-electric adjustment element in a defined deformation state of the tool so that it is possible to operate the tool without an external power supply. 
         [0009]    It is necessary to provide for different fine processing processes a multitude of different tools, thus the installation of an actuating adjustment element in each tool leads to enormous costs. Furthermore, this leads to adjustable tools having a large size and a large weight. Moreover, the supply of electrical power to an actuating adjustment element rotating in the tool is susceptible to dirt and humidity, and thus can only be performed in a sophisticated manner; nevertheless, the power supply of adjustment tools rotating in a tool are prone to wear and prone to error. 
         [0010]    The patent EP 0 491 724 B1 discloses a tool head for the application in machine tools. The machine tool comprises a slider which is rotatable perpendicular to the rotation axis and can be inserted in different cutting tools. The published patent application DE 10 2011 080 701 A1 describes a clamping mechanism for the slider which avoids an unintended shift of the slider during the operation of the tool head in a fast rotating motor spindle. The brochure KOMET KomTronic® U-Achssysteme, which can be downloaded from the homepage of the company Komet, describes a modular system which comprises an electrical drive with a machine interface onto which block tools can be clamped if necessary with the help of adapters. 
         [0011]    The brochure MAPAL TOOLTRONIC®, which can be downloaded from the homepage of the company Mapal, presents a modular system of different actuating tools for processing of arbitrary recesses and non-cylindrical bores. The modular system also has its own electrical drive which has again a machine interface for clamping onto a motor spindle and a modular interface at the tool side. Different actuating tools can be clamped on the modular interface and the different snap-on tools can be clamped to the actuating tool. 
         [0012]    Both modular approaches avoid the installation of an own drive unit into each adjustable tool. However, only very specific tools can be clamped or flanged to the drive unit or the tool head, respectively. Moreover, the tools have to be manually inserted in the actuating tool or the slider, respectively. 
         [0013]    The European patent EP 0 430 984 B1 describes a fine boring machine with an adjustable tool which is radially deflected by a piezo-electric actuator which is arranged in the working spindle of the fine boring machine, and wherein the piezo-electric actuator mechanically shifts a drawbar. The tool can manually be exchanged. 
         [0014]    Thus, the principle disclosed in the EP 0 430 984 B1—similar to the above mentioned modular approaches—avoids the installation of an actuating adjustment unit in each adjustable tool. However, the power supply of the actuator rotating in the working spindle has still the above discussed drawbacks. Moreover, each tool has to be manually clamped on the working spindle of the fine boring machine. 
         [0015]    The present invention is therefore based on the problem to provide an apparatus, a method and externally controllable adjustable tools which can automatically be clamped onto a motor spindle of a machine tool. 
       SUMMARY OF THE INVENTION 
       [0016]    According to a first aspect of the invention this problem is solved by an apparatus according to an exemplary embodiment. The apparatus may include a motor spindle for a machine tool that may include (a) a tool clamping system adapted to automatically clamp and release an adjustable tool; (b) a control rod arranged within the tool clamping system; and (c) a setting unit arranged on the B side of the motor spindle and adapted to adjust the adjustable tool via the control rod. 
         [0017]    The inventive apparatus allows adjustable tools to clamp via an automatic tool clamping system, and thus to meet the repeatability required for a series production. A control rod of an inventive apparatus does not need any space for its installation in an automatic tool clamping system on the A side of a motor spindle. The setting unit flanged at the B side the motor spindle does not extend in radial direction beyond the dimensions of the motor spindle. Thus, the combination of a control rod and a setting unit allows automatically adjusting adjustable tools without essentially impairing the compact setup of a motor spindle. Thus, the small size of the setting unit flanged at the B side of the motor spindle allows realizing very small actual dimensions in machine tools having several spindles. The above described control rod and setting unit can simply be integrated in the designs of existing motor spindles. 
         [0018]    The tool cutting edges of adjustable tools can be adjusted with a precision in the range of micrometers via the motor spindle according to embodiments. The wear of a cutting edge and/or the length extensions caused by heating can be compensated in a closed control loop. If necessary, the tool cutting edges can simultaneously be lubricated and/or cooled. Thus, an inventive apparatus allows the execution of contour machining processing processes, as for example the processing of cones and the fabrication of trumpet shapes to only mention two examples. 
         [0019]    In general, the quality of a processing process primarily depends on the quality of the tool, i.e. its tolerances, the cutting parameters of the tool, and the preciseness of the drilling spindle. Due to its bearing and its direct drive the design of a drilling spindle in form of a motor spindle fulfils highest preciseness requirements with respect to the position and the angular position of the spindle shaft. On this basis, an inventive apparatus allows to automatically and very precisely clamp adjustable tools. Thus, the inventive apparatus is predestined for the application in an automatic manufacture. 
         [0020]    According to a further aspect, the control rod has a drilled hole in axial direction to conduct at least one fluid through the control rod. According to a further aspect, the at least one fluid comprises a coolant, a gas or a gas mixture, in particular air and/or an oil. 
         [0021]    By conducting the fluid through a drilled hole of the control rod, the already mentioned lubrication and/or cooling of the adjustable tool can be realized. The fluid used for cooling and/or lubrication additionally removes chips from the processing site. Alternatively, the processing site, i.e. the tool can be cleaned through the drilling hole of the control rod via compressed air. 
         [0022]    In another aspect, the setting unit comprises at least one electric motor and at least one worm gear. According to a further aspect, the at least one worm gear comprises a planetary gear. In a beneficial aspect, the at least one electric motor comprises at least one actuator and the setting unit further comprises a clutch to couple the at least one worm gear to the actuator. In a preferred aspect, the at least one electric motor moves the control rod in axial direction via the at least one worm gear in order adjust the adjustable tool. 
         [0023]    According to a further aspect the setting unit controls the tool side end of the control rod after an electronic request of the axial position of the control rod with a mean deviation of ≦±100 μm, preferred ≦±50 μm, more preferred ≦±20 μm and most preferred &lt;±10 μm from a predetermined nominal position. 
         [0024]    The above mentioned adjustment accuracy of the tool cutting edges in the micrometer range is achieved by an essentially free of play transmission of the rotational movement of the rod of the actuator in a translational movement of the control rod by a planetary gear. If there is a clutch between the actuator and the worm gear, the clutch also has an essentially free of play construction. The term “essentially” means here as well as in other passages in this description a deviation from a nominal value which is within predetermined tolerance limits. 
         [0025]    Via a closed control loop the axial position of the tool-side end of the control rod can be retrieved, and thus the cutting edges of the tool can be adjusted with an accuracy in the micrometer range. 
         [0026]    According to still another aspect, the setting unit comprises a cooling unit. According to a further aspect, the cooling unit comprises a rotatory feed-through. In an advantageous aspect, the cooling unit adjusts the adjustable tool via the fluid conducted through the at least one control rod. 
         [0027]    It is an essential advantage of the defined apparatus that it can both adjust mechanically adjustable tools and fluid or media controlled tools. Thus, the defined apparatus is best suited for the application in an automated flexible manufacture, since it allows the use of already available adjustable tools. Fixedly executed tools, i.e. tools whose tool cutting edge cannot be adjusted, can of course be clamped to the above defined motor spindle. 
         [0028]    According to a further beneficial aspect the at least one tool cools and/or lubricates the adjustable tool. According to a further beneficial aspect an axial movement of the control rod adjusts the adjustable tool and the at least one fluid cools and/or lubricates the adjustable tool. 
         [0029]    The defined motor spindle offers the possibility to precisely adjust two different parameters, and thus independent from each other the tool cutting edges of the adjustable tool and to cool and/or lubricate a tool which is designed for this purpose with a predetermined quantity of a fluid in a defined way. 
         [0030]    In a further aspect a method for adjusting an adjustable tool which is detachably connected to a motor spindle of a machine tool has an automatic tool clamping system arranged in a motor spindle and the tool clamping system comprises a control rod which is arranged within the automatic tool clamping system. The method comprises the steps of: (a) clamping and releasing an adjustable tool via an automatic tool clamping system; and (b) adjusting the adjustable tool via a setting unit arranged on the B side of the motor spindle via a control rod. 
         [0031]    The inventive method allows to automatically clamp and to automatically control adjustable tools of the motor spindle from the B side. Thus, the design of the tools is not restricted. 
         [0032]    According to a further aspect, adjusting the adjustable tool comprises moving the control rod in axial direction. In a further beneficial aspect, moving the control rod in axial direction comprises transforming a rotational movement of a shaft of an electric motor into a translational movement of the control rod by a worm gear, in particular a planetary gear. 
         [0033]    In a further preferred aspect, adjusting the adjustable tool comprises conducting a fluid through a drilling hole of the control rod in axial direction. According to still another aspect, adjusting the adjustable tool comprises moving the control rod in axial direction and cooling and/or lubricating of the adjustable tool via conducting a fluid through a drilling hole of the control rod in axial direction. 
         [0034]    According to a second aspect, the problem of the present invention is solved by an apparatus according to another exemplary embodiment. The apparatus may include an adjustable tool that may include (a) a receiving part adapted to detachably engage with an automatic tool clamping system; and (b) a power transmission element adapted to detachably engage with a control rod arranged in the automatic tool clamping system in order to adjust the adjustable tool. 
         [0035]    Adjustable tools which have a power transmission element and thus can be mechanically controlled via a translational movement of a control rod of the above defined apparatus enable the setup of a modular system of adjustable tools for an automated and flexible manufacture. 
         [0036]    In still another preferred aspect, the power transmission element is further adapted to receive a fluid which is provided to the tool by an axial drilling hole of the control rod. 
         [0037]    A tool designed in this manner has two different parameters which allow to independently adjust the tool cutting edges of adjustable tools and to define the supplied amount of coolant/or lubricant at the processing site. 
         [0038]    Finally, in a further beneficial aspect, an adjustable tool comprises at least one spring adapted to counteract a force which is exerted by the power transmission element. 
         [0039]    In an adjustable tool of the prior art the control rod is fixedly connected with a tool and can generate a force acting in axial direction which is directed in the direction of the tool (push) or which is directed in the direction of the B side (pull). For an exchangeable tool, i.e. in particular at an automatically clampable tool, the control rod can only push on the power transmission element of the adjustable tool, however cannot exert a tensile force on the power transmitting element. A spring installed in the tool provides a force which counteracts the force of the control rod and thus allows a defined adjustment of the tool cutting edges of the tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]    In the following, detailed description presently preferred embodiments of the present invention are described with respect to the accompanying figures, wherein 
           [0041]      FIG. 1  illustrates a schematic representation of a motor spindle with an integrated automatic tool clamping system which clamps an adjustable tool and a setting unit for adjusting or setting an adjustable tool; 
           [0042]      FIG. 2  represents an example of a motor spindle for automatically clamping and adjusting adjustable tools; 
           [0043]      FIG. 3  represents an enlarged view of the B side of the motor spindle of the example of  FIG. 2 ; 
           [0044]      FIG. 4  shows an enlarged view of the A side or the tool side of the motor spindle of  FIG. 2  with an inflexible, i.e. not adjustable tool; 
           [0045]      FIG. 5  represents an enlarged view of the tool side of the motor spindle of  FIG. 2  with a first adjustable tool; 
           [0046]      FIG. 6  shows an enlarged view of the tool side of the motor spindle of  FIG. 2  with a second adjustable tool; and 
           [0047]      FIG. 7  represents an enlarged view of the A side of the motor spindle of  FIG. 2  with a third adjustable tool. 
       
    
    
       [0048]    While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF EMBODIMENTS 
       [0049]    In the following, presently preferred realization examples of the inventive apparatus and of the inventive method for automatically clamping an adjustable tool onto a motor spindle of a machine tool are explained. These exemplary explanations are described in the context of a motor spindle for a machine tool. Due to their bearings and their direct drives motor spindles are especially well suited for fine processing processes. However, an apparatus described here can also be applied in spindles of different types of machine tools. 
         [0050]      FIG. 1  schematically shows an over view of an inventive apparatus  100 . The inventive apparatus  100  comprises a motor spindle  110 . The A side indicates the side of the motor spindle  110  which carries a tool. The B side describes the opposite end of the motor spindle  110 . A setting unit  120  is flange-mounted at the B side of the motor spindle  110 . A spindle shaft  140  is arranged in the motor spindle  110 . A tool  130  is clamped on the spindle shaft  140  of the motor spindle  110  on the A side of the motor spindle. The spindle shaft  140  extends from the bearing on the B side to the tool interface on the A side. Common types of tool interfaces are for example HSK (hollow shank taper) or SK (steep taper). The inventive apparatus can be used for both tool interfaces as well as for further tool interfaces whose tool clamping system allow a central axial access. 
         [0051]    The spindle shaft  140  comprises an automatic tool clamping system  150  or an automatic tool clamping device  150 . The tool clamping device  150  comprises collet chucks  160  on the A side by which the tool  130  can automatically be clamped and released from the spindle shaft  140  of the motor spindle  110 . On the B side the tool clamping device  150  extends beyond the spindle shaft  140  in order to attach at the extending part a clamping and releasing apparatus. Details are discussed below in the context of  FIG. 3 . 
         [0052]    At the moment, automatic tool clamping systems  150  are available in the market which use different principles for clamping and releasing tools  130 . The clamping process and the releasing process are independent from whether a tool  130  is adjustable or not. The apparatus  100  described here is independent from the kind of the clamping system  150 . Rather, the described apparatus  100  can be used for all presently available and future automatic tool clamping systems  150  which have a central axial opening. 
         [0053]    A control rod  170  is arranged in the tool clamping device  150 . The control rod  170  extends from the tool interface of the spindle shaft  140  to the setting unit  120 . The control rod  170  has an axial drilling hole  180  which also extends from the setting unit  120  to the tool interface on the A side of the motor spindle  110 . The channel  190  of the tool  130  can be supplied with coolant and/or lubricant via the drilling hole  180  of the control rod  170 . 
         [0054]      FIG. 2  shows at a glance a realization example  200  of an apparatus for automatically clamping and adjusting adjustable tools. The motor spindle  210  has a spindle shaft  240 . The spindle shaft  240  is fixed in its position on the A side by the bearings  222  and  224  and on the B side by the bearing  226 . The stator  215  drives the spindle shaft  240 . The spindle shaft  240  comprises an automatic tool clamping system  250  which has collet chucks  260  on the B side. A control rod  270  which has a continuous axial drilling hole  280  is located in the tool holder  250 . A tool  230  is clamped on the spindle shaft  240  of the motor spindle  210  on the A side. The setting unit  220  is flange-mounted on the B side of the motor spindle  210 . 
         [0055]      FIG. 3  shows an enlarged cut out of the B side of the motor spindle  210  with the flange-mounted setting unit  220 . The setting unit  220  comprises an actuator  310  at its right end which is provided with electrical power via the connections  312  and  314  and comprises a housing setting unit  340 . The shaft  316  of the actuator  310  is connected to the planetary gear spindle  320 . The planetary gear spindle  320  is connected to the screw nut  322 . The screw nut  322  of the planetary gear spindle  320  is arranged in a piston  345  of the housing setting unit  340 , wherein the piston  345  is moveable in axial direction. A rotary feed-through  330  is also arranged in the moveable piston  345 . The axial control gear, which comprises in the example of  FIG. 3  the planetary gear spindle  320  and the screw nut  322 , transforms the rotational movement of the shaft  316  of the actuator in a translational movement of the control rod  270 . The maximum stroke  342  of the control rod  270  is 26 mm in the example represented in  FIGS. 2 and 3 . A rotation of the shaft  316  corresponds to an axial translational movement of the control rod of 2 mm. A reserve  344  of 5 mm is foreseen for wear compensation which is contained in the maximum stroke of 26 mm. 
         [0056]    The proximity switch  325  serves as a reference point sender unit for the absolute value transmitter of the actuator  310  which is retrieved when the machine tool is started. The current position of the control rod  270  is calculated via the data of the absolute value transmitter of the actuator  310 . 
         [0057]    The left end of  FIG. 3  presents the end  355  of the spindle shaft  240 . The tool clamping device  250  is arranged in the spindle shaft  240 . The hydraulic unit  364  which is connected to the automatic tool clamping device  250  serves for automatically clamping and releasing the tool  130 ,  230  via the hydraulic piston  362  by shifting the tool clamping device  250  in axial direction. 
         [0058]    As already mentioned above, the control rod  270  has a continuous axial drilling hole  280 . The drilling hole  280  is connected to the rotary feed-through  330 . The passage of the rotary feed-through  330  to the control rod  270  is sealed by a seal ring. A fluid can be provided to the rotary feed-through via the connection  332 . In this description the term fluid comprises coolants, lubricants, oils and gasses or gas mixtures for adjusting fluid controlled tools as well as generally for cooling, lubricating and cleaning the tools  130 ,  230  or the tool cutting edges of the tools  130 ,  230 . Presently, air is typically used as coolant and for cleaning the tools  130 ,  230 . 
         [0059]    Thus, the tool can be supplied with respective lubricants and/or coolants in a control manner via the drilling hole  280  of the control rod  270 . Adjustable tools  130 ,  230  controlled by fluid can be controlled or adjusted by adjusting a respective pressure at the connection  332  of the rotary feed-through  330  independent from an axial translational movement. Details are explained in the context of the discussion of  FIG. 6 . The term tools controlled by fluid means in this description the adjustment or setting of cutting edges of adjustable tools by the provision of a defined quantity of a fluid to the tool per time unit. 
         [0060]    The rubber seal  336  of the housing setting unit  340  covers the access to the movable piston  345  and avoids the penetration of dirt on the moveable piston  345  of the housing setting unit  340 . The leak tightness of the rotary feed-through  330  can be checked via the leakage connection  334 . Instead of coolant or lubricant, the tool  130 ,  230  can alternatively be supplied also with compressed air or cleaning air for cleaning the processing side via the connection  332 . 
         [0061]    The arrangement  400  of  FIG. 4  shows the A side of the motor spindle  210  of  FIG. 2 . The motor shaft  240  of the motor spindle  210  carries a tool  430  according to the prior art. The collet chucks  260  of the tool clamping device  240  arranged in the spindle shaft  240  clamp the tool  430  on the spindle shaft  240  of the motor spindle  210 . 
         [0062]    The spindle shaft  240  has drilling holes or openings  290 . The openings  290  end at the inner cone and at the front side of the tool holder of the spindle shaft  240 . After releasing the collet chucks  260 , the control rod  270  carries on in the direction of the tool  430  and mechanically pushes the tool  430  from the spindle shaft  240 . 
         [0063]    The control rod  270  ends in a connection part or a power transmission element  410  which is arranged in the shaft or receiving part  435  of the tool  430 . The connection element  410  has a channel  415  which is connected to a channel  490  available in the tool  430 . The cutting edges  440  of the tool  430  are supplied with coolant and/or lubricant via the openings  495  which are connected to the channel  490 . The tool  430  is an example of an inflexible tool, i.e. the tool cutting edges  440  cannot be adjusted or can at least not automatically be adjusted. The passage of the control rod  270  to the power transmission portion  410  of the tool  430  is sealed via a seal ring (not represented in  FIG. 4 ). 
         [0064]    The configuration  500  of  FIG. 5  represents again the A side of the motor spindle  210  of  FIG. 2 . In the example represented in  FIG. 5 , the tool  530  which is adjustable or controllable during a processing process is clamped on the spindle shaft  240  of the motor spindle  210 . The adjustable tool is a drilling tool. The connection part or power transmitting part  510  of the tool  530  is again connected to the control rod  270 . Similar as explained in the context of  FIG. 4 , the channels or openings  590  and  595  of the tool cutting edges  540  of the tool  530  can provide coolants and/or lubricants in a defined manner via the connection  332  of the rotary feed-through  530 , the drilling hole  280  of the control rod  270  to the channel  515  of the power transmission element  510 . As already explained during the discussion of  FIG. 4 , the passage of the control rod  270  to the power transmission element  510  of the tool  530  is sealed via a seal. 
         [0065]    The tool  530  further comprises a fork  570  and an adjusting head  560 . A preloaded spring assembly  580  shifts the fork  570  in the direction of the spindle shaft  240 . Instead of a spring or a spring assembly, for example a pneumatic pressure unit can also be used. The position of the fork  570  is illustrated in  FIG. 5  by the reference number  537 . In the position  537 , the tool cutting edge  545  of the tool  530  is retracted. The adjusting head  560  can be adjusted by bending the inner tool part  550  via a translation movement of the control rod  270 . For a rough drilling process the fork  570  of the tool  530  is shifted with a stroke  538  of up to 5 mm from the shaft of the tool part  550  against the force of a preloaded spring assembly  580 . This shift is symbolized in  FIG. 5  by the reference number  538 . The bending of the inner tool part  550  leads to a radial setting of the tool cutting edge of the tool  530  in a direction away from the rotation axis. In this state  538 , i.e. with extended tool cutting edge  541  of the tool  530  rough drilling processes are executed (semi finish drilling). 
         [0066]    For fine drilling or for finish-drilling the control rod  270  is retracted up to 5 mm, i.e. is moved in the direction towards the B side. As a consequence of which the spring assembly  580  shifts the fork  570  towards the spindle shaft  240  and the bending of the inner tool part  550  is reversed. Thus, the tool cutting edge  541  of the tool  530  returns to its starting position  540 . 
         [0067]    The spring or the spring assembly  580  of the tool  530  of  FIG. 5  provides the tensile force of the control rod which is missed in the automatically clampable tool due to the loose coupling of the control rod  270  to the power transmission element  510 . The externally controllable and automatically clampable tool  530  shown in  FIG. 5  operates essentially without play. The tool  530  achieves a repeatability in the micrometer range. 
         [0068]    A shift  536  of approximately 5 mm is again foreseen between the shaft or the receiving part  535  of the tool  530  and the fork  570  in order to compensate the tool wear. 
         [0069]    The arrangement  600  of  FIG. 6  shows again the tool side of the motor spindle  210  of  FIG. 2 . In the example of  FIG. 6 , an adjustable tool  630  of the prior art is clamped on the spindle shaft  240  of the motor spindle  210  for a fine processing process, more precisely for a fine drilling process. The adjustable tool  630  is controlled by a translational movement of the control rod  270  in the example of  FIG. 6 . Similarly, as explained in the discussion of  FIG. 5 , the end of the control rod  270  and the connection part or the power transmission element  610  of the tool  630  are loosely coupled via a preloaded spring. The power transmission element  610  of the tool  630  is connected with the bolt  650 . The bolt  650  is mounted in the tool  640  acting as a tightly lapped sliding core. The bolt  650  has on its front end a carbide insert  670 , which acts via a sphere  675  and the pin  677  on the cutting edge  640  of the tool. 
         [0070]    The tool cutting edge  650  of the tool  630  can be adjusted or controlled by shifting the bolt  650  via the control rod  270  in axial direction. The more the control rod  270  presses the bolt  650  via the power transmission element  610  into the tool  630  the more the tool cutting edge  640  of the fine processing tool  630  is extended. If the control rod  270  is retracted the spring assembly  655  pushes the bolt  650  against the shaft or the receiving part  635  of the tool  630 . If the bolt  650  is shifted towards the receiving part  635  of the tool  630 , the bending of the blanking die holder  680  is relaxed, whereby the tool cutting edge  640  of the tool  630  retracts so that the tool  630  can be retracted from the drilling hole without touching the wall of the drilling hole by the tool cutting edge  640 . The blanking die holder  680  is fixed to the tool  630  with the fixing elements  660  which are screws in the example represented in the tool  630  of  FIG. 6 . In the tool  630  represented in  FIG. 6  the diameter of the tool cutting edge  640  can be adjusted in the range of 0.4 mm to 0.7 mm. The repeatability of the diameter of the tool cutting edges  640  of the tool  630  is in the range of 10 μm. 
         [0071]    The power transmission element  610  has a channel  650  for transmitting a fluid. The tool  630  can be cooled and/or can be lubricated by providing a respective quantity of a fluid via the openings  690  through the drilling hole  680  of the control rod  270  and the channel  650  of the power transmission element  610 . 
         [0072]    Finally, the arrangement  700  of  FIG. 7  shows the A side of the motor spindle  210  on which spindle shaft  240  a second fine processing tool  730  according to the prior art is clamped. The adjustable tool  730  which is exemplary represented in  FIG. 7  is a boring tool for finish boring. The power transmission element  710  has a channel  715  which is connected with the drilling hole  280  of the control rod  270 . The channel  715  extends within the tool  730  up to the tool cutting edge  740 . By introducing a fluid under a corresponding pressure into the rotary feed-through  330  the tool cutting edge  740  of the tool is extended in a defined manner. If the pressure is removed, the cutting edge  740  of the tool  730  retracts to the extent in the tool  730  so that the cutting edge  740  does not damage the wall of the drilling hole when the tool is retracted. The blanking die holder  780  is fixed to the tool  730  with fixing elements  760  which are also screws in the example of  FIG. 7 . Similar as explained in the context of the tool  630  of  FIG. 6 , extending and retracting the tool cutting edge  740  occurs for the tool  730  controlled by fluid or controlled by medium of  FIG. 7  via material bending of the blanking die holder  780 . 
         [0073]    The tool  730  is pre-adjusted against the resistance of the spring assembly  770  via the planetary gear spindle  755 , the nut screw  750  and the journal  790 . To compensate the wear of the tool cutting edge  740  of the tool  730 , the tool cutting edge is readjusted via the journal  790  and the planetary gear spindle  750 . The repeatability of the diameter adjustment of the tool controlled by medium is in the micrometer range. 
         [0074]    The apparatus explained in the present application allows both an automatic clamping and an automatic adjustment and setting of adjustable tools. It does not matter whether the adjustable tool is designed for a mechanical (i.e. by a translational movement of the control rod) or for a fluid controlled adjustment (i.e. by providing a fluid with a respective pressure). 
         [0075]    Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.