Abstract:
A tool turret includes a housing ( 10 ) for connection to a machine tool, and an electric drive motor ( 28 ). A tool disk ( 14 ), is mounted to rotate relative to the housing ( 10 ) about a longitudinal axis ( 34 ), may be fixed in selected angular positions, and has recesses ( 16 ) for machining tools ( 18 ). At least one rotating machining tool ( 18 ) may be driven by the drive motor ( 28 ) using shafts ( 24, 30 ), extending perpendicular to the longitudinal axis forming the swiveling axis of the tool disk ( 14 ). The electric drive motor ( 28 ) is arranged within the tool disk ( 14 ). The driveshaft ( 30 ) from the electric drive ( 28 ) is aligned with the driveshaft ( 24 ) for the machining tool ( 18 ), and is aligned with the driveshaft ( 24 ) for the machining tool ( 18 ) or extends parallel to it. An economical drive design for machining tools on a tool turret is achieved, with a small installation volume.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a tool turret having a housing to be connected to a machine tool, with an electric drive motor. A tool disk is mounted rotatably relative to the housing, may be fixed in selectable angular positions, and has recesses for machining tools. At least one rotating machining tool is driven by a drive motor by shafts extending perpendicular to the longitudinal axis representing the pivot axis for the tool disk. 
   BACKGROUND OF THE INVENTION 
   DE 40 18 543 C1 discloses a tool turret having a housing to be connected to the machine tool. The housing has an electric drive motor and a tool disk mounted rotatably relative to the housing. The tool disc has recesses for machining tools, at least one of which is configured for rotatable mounting of the tool. The machining tool may be driven by the drive motor by shafts which are interconnected by gearing. A hollow column is mounted concentrically with the axis of rotation of the tool disk, and has at least one line included in a system provided for transmission of energy, lubricant, coolant, pressure means, or auxiliary forms of energy. The hollow column is immobile relative to the housing. One of the shafts driven by the drive motor is mounted in the hollow column and connected by the gearing to the other shaft by way of which the rotatably mounted tool may be driven when the recess into which this tool is introduced is in the operating position. 
   This tool turret permits transmitting the auxiliary forms of energy or auxiliary means to the tool modules, tools, or the tools requiring such forms of energy, in a space conserving, problem-free, simple, and cost-effective manner. However, in that the drive system involves shafts and gearing, the tool drive configuration still requires much structural space. Because of the large number of elements, the drive system is also subject to wear, is correspondingly cost intensive in production, and requires a certain degree of maintenance. 
   DE 39 00 443 A1 discloses a variable-angle packaged unit for machine tools including turret heads. Fixable cutters are retained in recesses mounted pivotably about a stationary table element along a longitudinal axis. Two table elements of the turret head are mounted pivotably relative to each other around the longitudinal axis by an electric drive integrated into the tool disk. Appropriate gearing down for the rotatable table element by way of a planet gear unit is possible. Driving of rotating machine tools is not possible. 
   DE 39 04 631 A1 discloses another turret head solution for machine tools, for turning machines in particular. An insertible rotating machine tool is driven by gearing and the drive shaft for the machine tool extending parallel to the main drive shaft for the turret head. The turret head is in the form of a tool disk. The central electric drive is positioned outside the table unit of the tool disk, so that a compact structure is not possible. In addition, since the electric drive is separated by a large axial distance from the tool disk driven by it together with the respective machining tool, inaccuracies in control of the structural components (disk, tool) are not excluded. 
   SUMMARY OF THE INVENTION 
   Objects of the present invention are to provide an improved to tool turret having the advantages of conventional tool turrets and being cost-effective, taking up even less structural space, and permitting reduction of maintenance costs as a result of increase in reliability of operation. 
   The foregoing objects are obtained according to the present invention, by a tool turret with an electric drive motor mounted inside the tool disk, and with the driven shaft of the electric drive motor mounted to be aligned with or parallel to the drive shaft of a machining tool. The tool turret of the present invention suffices without costly shafts, the position of which is to be moved a number of times. The direct drive configuration permits the driven shaft of the electric drive motor to operate in alignment with the drive shaft of the machining tool. The overall configuration, that is, drive motor with corresponding shaft elements, may be integrated as one packaged unit directly into the tool disk to conserve space. No structural space is required outside the tool disk. Consequently, “slimline” exterior housing configurations may be achieved with this tool turret which is an advantage especially in view of the restricted space available in the case of machine tools which may be outfitted with the widest possible variety of tools and tool groups. In addition, production and maintenance costs are reduced as a result of the restricted variety of elements. The direct drive configuration also ensures zero backlash, an aspect which on the whole promotes machining accuracy. Advantageous embodiments are also obtained if the driven shaft is mounted in parallel with the drive shaft. With this parallel arrangement, between the shafts, a direct coupling or a gearing configuration may be provided, such as one in the form of toothed gearing for transmitting the power output of the motor to the machine tool. The structure of the present invention is distinctly compact and “slim.” 
   In one especially preferred embodiment of the tool turret of the present invention, the electric drive is a brushless motor, an asynchronous motor or three-phase synchronous motor, preferably in the form of an interior rotor motor. The stator is connected to the housing of the motor with the coil windings, and encloses the rotor with the magnet elements. The rotor is connected to the driven shaft of the electric motor. Electric motors used for this purpose have continuous speed control. The speed is a function of the frequency of the current supplied but otherwise is more or less independent of the load, an aspect of particular advantage for machine tools which may be subjected to varying loads during machining. In addition, such electric motors may be used to reach very high motor speeds, ones which may quite possibly range from 15,000 rpm to 80,000 rpm. The motors used for the purpose may be provided for direct driving of the machine tool and are very compact. Because of their high speeds, such motors make high rated power available. 
   In another preferred embodiment of the tool turret of the present invention with at least one gear unit, preferably a single-stage or multistage planet gear unit, reduction of the speed of the drive motor occurs between the driven shaft of the electric drive motor and the drive shaft of the machine tool. The planet gear unit permits distinctly space-saving and reliably operating reduction of the high speed requirement of the electric motor. A customary machining speed may be made available for the machine tool by the speed reduction by way of the planet gear unit. Preferably, the driving gear of the planet gear unit is driven by the driven shaft of the electric drive motor. The drive wheel in turn drives at least one planet wheel of the gearing which always rolls along a stationary ringshaped gear housing element. The respective planet wheel transmits the drive output arising during circulation of the planet wheel to the drive shaft of the machine tool by way of a carrier element (web). 
   Should additional speed reduction prove to be necessary, advantageously an additional planet gear unit is present along with the first, one whose drive wheel may be driven by the driven shaft of the first planet gear unit and whose output arising during circulation of its respective planet gear unit may drive the drive shaft of the machining tool. Even very high-speed three-phase synchronous motors may be stepped down by the two planetary gear units to a nominal speed which may be classified as ideal for the drive of a machining tool. The speed may optionally be even further reduced by serial mounting of additional planet gear units. 
   In one preferred embodiment of the tool turret of the present invention, a coupling system is provided between the driven shaft of the drive motor and the output in the form of a shaft of the respective planet gear unit mounted last upstream from the drive shaft of the machining tool. The coupling system preferably may be controlled by a hydraulic operating system which in the coupled or uncoupled position drives the drive shaft of the machine tool for rotary propulsion of the machine tool or releases this shaft by means of the tool disk for a process of machine tool pivoting, respectively. The coupling system also permits release of the machine tool in an extremely short time for a machine tool pivoting process, and accordingly, introduction of a new tool for immediate driving. Consequently, the introduction and replacement processes proceed very rapidly. Every machining tool introduced as a replacement is immediately available for metal cutting. 
   In another especially preferred embodiment of the tool turret of the present invention, the drive motor is mounted on a support on the side of the housing to be stationary. The tool disk with its tool recesses is pivotably mounted around the support. The support forms a torque converter support. The forces and possibly vibrations associated with the high torque values of the drive and transmitted to the drive housing are diverted to the other housing by the torque converter support. As a result, the electric drive motor with its very high speeds is reliably held on the housing side, and in this way, is securely “anchored” for transmission of the high speeds. 
   In another preferred embodiment of the tool turret of the present invention, the electric drive motor may be cooled by a cooling device whose coolant lines extend into the support of the housing. The cooling device used permits controlling the amounts of heat associated with the high drive outputs, so that the machining accuracy is not impaired. Preferably, the hydraulic supply lines for the hydraulic operating device are mounted to extend at least to some extent into the support of the housing, with the lines for end position control of the coupling and/or operating device. In this way, all relevant supply and energy lines may be incorporated by design by way of the support into the pivotable tool disk with its integrated drive configuration. 
   Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings which form a part of this disclosure: 
       FIG. 1  is a side elevational view in partial section, of a tool turret for a machine tool according to an embodiment of the present invention; 
       FIG. 2  is a top plan view of a planet gear unit with a driving or sun wheel and three planet gears which roll along a stationary annular gear of the tool turret of  FIG. 1 ; and 
       FIG. 3  is a side elevational view in section of two serially mounted planet gear units (partly shown) as viewed along line I—I of FIG.  2 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A tool turret has a housing  10  which is secured in position on a machine tool (not shown), for example, on a slide of such machine tool, by a threaded connection  12 . A tool disk or tool carrier is mounted on one end of housing  10  and is rotatable relative to the housing. The tool disk has recesses  16 , for machine or machining tools  18 , uniformly distributed over its circumference. The tools are configured as tool modules, and have a rotating, metal cutting tool  20 , for example, one in the form of a drill or milling cutter. In the exemplary embodiment, the recesses  16  are in the form of drilled holes extending radially. A shank  22  of the machine tool may be inserted into each of these drilled holes. A drive shaft  24  projects above such shank  22 . The shank  22  may be provided on its external circumference side with positioning gearing (not shown in detail), so that the machining tool  18  may always be secured in position in the recess  16  by a corresponding counterpart in the tool disk  14  as a tensioning device. For simplification of illustration; only one inserted modular machining tool  18  is been shown in FIG.  1 . The tensioning device is disclosed in EP 0 585 600 B1, for example, and accordingly will not be described in greater detail at this point. 
   An electric drive motor  28  is mounted in the interior  26  of the tool disk  14 . The driven shaft  30  of the electric motor  28 , graphically shown in FIG.  1  and indicated as an extension in  FIG. 3 , is in alignment with the drive shaft  24  along a common axis of rotation  32 . Rotation axis  32  extends perpendicularly to a longitudinal axis  34  forming the pivot axis for the tool disk  14 . The machining axis  36  for the metal cutting tool  20  is mounted either in parallel with the longitudinal axis  34  and perpendicularly to the axis of rotation  32 , or in parallel with the axis of rotation  32  and perpendicularly to the longitudinal axis  34 . 
   The electric motor  28  is mounted in a motor receptacle  38 , a part of the housing  10 . The motor receptacle  38  is mounted to be stationary. The tool disk  14  may assume a predetermined pivot position relative to this motor receptacle  38 . The tool disk  14  has, on its free frontal surface, a front cover plate  40  which covers the motor receptacle  38  externally. The inner drive configuration is readily accessible from the exterior when the plate  40  is removed. This cover feature distinctly facilitates any maintenance and repair operations. 
   The three-phase electric motor  28  is a three-phase synchronous motor with a very high speed, 15,000 rpm, for example. The motor is preferably in the form of an internal armature motor in which the stator (not shown) with coil windings connected to the housing of the motor  28  encloses the rotor (not shown) and with the magnet elements connected to the driven shaft  30  of the electric drive motor  28 . 
   To reduce appreciably the high speed of the electric drive motor  28  for the machining tool  18 , a reduction gear, preferably in the form of planet gear unit  42  is provided between the driven shaft  30  of the electric drive motor  28  and the drive shaft  24  of the machining tool  18  (see FIG.  2 ). The drive wheel or gear  44  of the planet gear unit  42  may be driven by the driven shaft  30  of the electric drive motor  28  (see FIG.  3 ). For this purpose, the driven shaft  30  extends through the gear housing  46  of the planet gear unit  42  for direct driving of the drive wheel  44 . The drive wheel in turn drives three planet wheels or gears  48 , only planet wheel  48  shown as being uppermost in  FIG. 2  being shown in FIG.  3 . The three planet wheels  48  in turn all roll along the stationary annular gear housing  46 . The gear housing  46  has, on its inner circumference, gearing mating with the teeth of the planet wheels  48 . Similarly, the drive wheel  44  with its external gearing is mated to the three planet wheels  48 . 
   The planet gear unit is of conventional design, and will not be discussed in greater detail at this point. The operation of the planet gear unit  42  will be explained only to the extent necessary for understanding of the present invention. The planet wheels  48  in turn have central shafts  50  engaged in a carrier element  52 , also termed “web” in technical language. The three carrier elements  52  are all guided rotatably in the central shafts  50  and are otherwise bent twice at an angle ( FIG. 3 ) to transmit the rotary movement of the planet wheels  48  to a common driven end  54  of the planet gear unit  42 . The driven end  54  is in turn engaged in the gear housing  46  for the torque transmission. If the respective driven end is connected directly to the drive shaft  24  of the machining tool  18 , the speed of the drive motor  28  may be reduced by a factor of 5, so that 3000 rpm are obtained for the machining tool  18 . Since the speed of the drive motor  28  is continuously variable, the speed reduction of the machining tool  18  may be predetermined over a wide range. 
   If the electric motor  28  generates higher speeds, which quite possibly may range from 50,000 rpm to 80,000 rpm, the first planet gear unit  42  may be coupled to a second planet gear unit  56 , as is shown in diagram form in FIG.  3 . The driven end  54  of the first planet gear unit  42  is guided or coupled to the input side  58  of the second planet gear unit  56 . The drive wheel  44  of the second planet gear unit  56  is thus driven. This second drive wheel  44  then transmits its rotary movement to the planet wheels  48  of the second gearing  56 . Driven end  60  is transmitted to the drive shaft  24  of the machining tool  18  by the carrier elements or webs  52 . The configuration shown in  FIG. 3  may optionally be further supplemented by serial mounting of the planetary gears (not shown), so that the speed of the electric motor  28  may be reduced in this way in specific stages. Very good speed reduction accompanied by the saving of space may be achieved with the planet gear units  42  and  56 . It is also possible, however, to reduce the speed correspondingly with other sets of reduction gearing. Since in the illustrated embodiment all shaft elements  30 ,  54 ,  60 , and  24  are aligned with each other, specifically, relative to the axis of rotation  32 , unbalance problems are largely prevented, and quiet operation of the drive configuration free of vibration is made possible. 
   As is illustrated in  FIG. 1  in particular, a coupling device  62  is provided between the wavelike driven end  60  of the shaft and the drive shaft  24  of the machining tool  18 . The coupling device  62  is actuated by a hydraulic or pneumatic operating device  64 , the coupled position being shown in FIG.  1 . The operating device  64  has two annular fluid chambers  66  and  68 . In the coupled position shown in  FIG. 1 , the lower fluid chamber  68  is under pressure applied by a pressure medium, while the upper fluid chamber  66  is more or less kept free of pressure other than pressure of surrounding air. In the respective pressure application situation, the coupling sleeve  70  is in its upper position as shown in  FIG. 1  to entrain a coupling element  72  effecting the coupling process. A connecting device  74  with a ball or roller bearing  76  is provided for the entrainment movement of the coupling sleeve  70  with coupling element  72 . The ball bearing  76  positions the coupling element  72  rotatably in the sleeve  70 , with the coupling sleeve  70  mounted so as to be stationary. Such positioning is necessary to permit the coupling element  72  to transmit the rotary movement of the driven end  60  of the shaft to the drive shaft  24  of the machining tool  18 . 
   For the purpose of entraining the drive shaft  24  of the machining tool  18 , drive shaft  24  has on its external circumference toothing or teeth  78  for mating to interior toothing or teeth of the coupling element  72 . This coupling element  72  has on its upper side, as seen in  FIG. 1 , a recess  80 . A corresponding recess  82  is on the opposite side of the coupling element  72  so that the exterior toothing  84  may mesh with the interior toothing  86  of the coupling element  72 . The interior toothing  86  is present only in the area of the lower free end of the coupling element  72 . In addition, the structural depth of the recess  82  is designed so that, when the coupling element  72  is lowered over the coupling sleeve  70 , the driven end  60  of the shaft may enter the second recess  82  and remain there until the drive shaft  24  of the machining tool  18  has been withdrawn and has fully cleared the recess  80 . 
   For the lowering movement, the fluid chamber  66  is pressurized and the level of pressure in the fluid chamber  68  is lowered to the ambient pressure level. The operating device  64  then forces the coupling element  72 , by way of the coupling sleeve  70  as thus pressurized, from its upper position in  FIG. 1  into its lower position (not shown). In this lower position, the drive shaft  24  of the machining tool  18  is then freed and the tool disk  14  may be pivoted by appropriate actuation about its longitudinal axis  34  until another machining tool positioned in another recess  16  replaces the machining tool  18  shown. By reversal of the fluid control process for the chambers  66 ,  68 , the coupling element  72  may be returned by way of the coupling sleeve  70  to its coupling position and the output of the motor  28  may then be transmitted to the machining tool  18  when the coupling is effected. The coupling sleeve is appropriately sealed on the inside and outside to prevent undesirable fluid escape. In order for the coupling element  72  to be able to rotate and still effect axial longitudinal displacement along: the axis of rotation  32 , a needle bearing cage  88  is mounted on the outer circumference side of the coupling element  72 . 
   As has already been stated, the electric drive motor  28  is retained in a motor receptacle  38  which in turn is connected to a support  90  as a torque support. The rod-shaped support  90  accordingly carries on its free end the motor receptacle  38 . On its upper side, the coupling device  62  is mounted and is integrated into the housing  10 , especially in the area of its other end. The electric drive motor  28  is enclosed in a cooling device  92 , the coolant lines  94  of which extend into the support  90 . The heat levels accompanying the high specific performance levels may be reliably removed from the motor receptacle  38  and accordingly from the tool disk  14  by the cooling device  92 . The supply lines  96  for the operating device  64  also extend into the support  90 . In addition, an end position switch  98 , the transmission line  100  of which also extending into the support  90 , is also provided for monitoring the operating situation of the coupling sleeve  70  or for the coupling element  72 . Consequently, all essential supply and information lines are carried centrally by the support  90  into the interior of the tool disk  14 . 
   A compact drive solution is made available by the tool turret of the present invention, with very high drive output values and drive speeds. The speeds may be transmitted directly to a machining tool or suitably reduced by way of gear steps. Since all drive shafts are in alignment on a common axis, unbalance phenomena are prevented. Such prevention works to the advantage of accuracy of machining by machining tools. A slimline design is obtained and the structural space available in the tool disk is efficiently used as a result of integration of the drive configuration into the tool disk, on the housing side in particular. 
   While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.