Patent Application
20120189394
The invention relates to a modular spindle unit for forming a multi-spindle machining head for a machine tool as described in the preamble of claim 1.
Multi-spindle machining heads that may be attached for example to the traverse drive of a machine tool are known from the related art. This particularly enables the machining head to be displaced and positioned in three axes. Tools, for example drills, milling heads or saw blades, may be attached to each of the different tool spindles of the machining head and may be driven in rotary manner. Such multi-spindle machining heads are used particularly in the furniture making industry to enable economical machining of panel-like parts, for example furniture fronts, carcasses, panels or insulating plates.
There are a number of different approaches with regard to the design and construction of such multi-spindle machining heads. According to a first construction type, all tool spindles are located in a solid gear block, which in turn consists of several bearing and distribution plates. This gear block must be designed and built afresh for each spindle arrangement, which is associated with high costs and long delivery times. It is also not possible to change the spindle arrangement and the number of spindles subsequently.
As an alternative to this, multi-spindle machining heads are also known in which the individual drive spindles are supported in modular spindle units. These modular spindle units are then combined to form the multi-spindle machining head and are attached to the machine tool as a single component.
Document DE 102 59 285 A1 describes modular spindle units that are designed without their own drive motor. The individual spindles are driven via a gear drive, which itself is driven by a central motor. The disadvantage of this design is that the individual working spindles cannot be driven individually and independently of each other, which means that it is not possible for them to rotate in different directions, function at different machining outputs, and dedicated sensor equipment cannot be associated with the spindles individually. Furthermore, the gear drive causes significant wear and therefore necessitates frequent servicing of the machinery.
Document DE 198 22 372 A1 describes a machining head that is formed from several spindle units, wherein the individual spindle units are attached to a common module carrier. Each of the spindle units is equipped with its own drive motor for rotary drive. Axial displacement drives are provided so that the spindle units may be extended relative to the module carrier independently of each other. The axial displacement drives are disposed offset parallel to the individual spindle units, and this has the disadvantage that it is not possible to arrange the spindle units correspondingly closely to the module carrier. Drilling patterns with very small drill spindle clearances, for example of just 30 mm, cannot be created in this way.
Document DE 101 20 883 A1 also describes a drilling unit having multiple spindle units, which may be displaced axially by axial drives that are offset parallel to the spindle units.
Document DE 199 50 715 A1 describes a machining head having multiple modular spindle units, in which the axial displacement drives are arranged coaxially with the center axis of the drive spindle. In this case, the drive spindle protrudes through the drive motor that is provided for rotary drive, and the drive motor itself is fixed with its spindle unit housing. In order to enable axial displacement of the drive spindle protruding through the drive motor, the rotor and a section of the drive spindle have a polygonal gear system, via which the driving torques may be transferred from the rotor of the drive motor to the drive spindle, and a push-fit system is created at the same time. The disadvantage of this engineering solution is that the polygonal gear system is very labor-intensive to manufacture. Moreover, the diameter of the spindle unit is increased substantially by the polygonal gear system between the drive spindle and the drive motor, and the spindle units are disposed correspondingly less closely together on the machining head. In addition, the gearing between the drive motor and the drive spindle may lead to undesirable rotary oscillations.
The object of the present invention is to suggest a new modular spindle unit for forming a multi-spindle machining head for a machine tool that does not suffer from the disadvantages of the related art described in the preceding. In this context, the aim is particularly to create a simple construction of the spindle unit and to enable the spindle units to be disposed very closely together on the machining head.
This object is achieved by the spindle unit according to the teaching of claim 1.
Advantageous embodiments of the invention are the objects of the dependent claims.
The invention is based on the underlying idea that axial movement between the drive motor and the drive spindle should be avoided. In this way, expensive and bulky means for transferring torque between the drive motor and the drive spindle, which also enable axial offset between the drive motor and the drive spindle, may be dispensed with. To achieve this object, the drive motor of the spindle unit according to the invention is mounted so as to be axially displaceable in the module housing, and may be displaced axially in the module housing by driving the axial actuating device together with the drive spindle along the common center axis. In other words, this means that the drive motor and the drive spindle form a single unit for the purpose of axial displacement. This results in very thin spindle units, which may be manufactured inexpensively. With volume production, preassembly and prior testing of the spindle units, the spindle units may be prefabricated with low type variance, and may be very quickly adapted for use with a wide range of multi-spindle machining head configurations as needed. In addition, rotary oscillations at the drive spindle are avoided. If the configuration of an existing machining head is to be altered, this may be easily carried out by simply dismounting and remounting the spindle units, since each spindle unit is a self-contained functional unit.
A particularly inexpensive and compact construction may be achieved if the rotor axle of the drive motor and the drive spindle are materially bonded to each other. To this end, the rotor axle of the drive motor and the drive spindle may be manufactured integrally as a single part, for example. In this way, elements for transferring torque between the rotor axle and the drive spindle may be dispensed with, since they are materially bonded to each other.
In particular, transferring drive energy and/or transferring information is essential in order to operate a drive motor. Normally, drive energy is transferred to the drive motor in the form of electrical energy. Because the drive motor is mounted so as to be axially displaceable in the module housing, hard-wired supply lines cannot be used for transferring the drive energy. It would be possible to use sliding contact rails, but this would necessitate considerable construction engineering effort and would also lead to significant safety problems. It is therefore particularly advantageous if the supply line for transferring drive energy has a length compensation element for adapting the length of the supply line. The length compensation element enables the geometry of the supply line to be adapted to the respective position of the drive motor in the module housing.
If the drive motor itself is driven electrically, the drive energy may be transferred via a power supply cable. In order to create the length compensation element, the power supply cable may include a spirally coiled section. The elasticity of such a spirally coiled section of the supply cable enables it to contract or extend within certain length limits, to thereby assuring the necessary length compensation.
Because it is flexible, the spirally coiled power supply cable must be routed on the spindle unit so as to avoid operating malfunctions. The spirally coiled power supply cable may be routed simply by winding the supply cable several times around a drive rod of the axial actuating device. In this context, the drive rod may be in the form of a kind of piston rod, for example, if the axial actuating device is driven electromechanically, pneumatically, or hydraulically. The drive rod thus extends through the coils of the power supply cable, so that the cable is held in place precisely on the drive rod.
In principle, this module housing of the individual spindle units may be of any structural design. According to a preferred embodiment, the module housing encloses two case plates and at least two rod axles. Each case plate forms the axial limit of the spindle unit. The rod axles connect the two case plates to each other and ensure that a fixed space remains between them. This forms a kind of open cage, which essentially constitutes the module housing and in which the various components of the spindle unit may be mounted, fixed to the housing, rotationally immovable, and/or axially displaceable. The use of thin rod axles enables the raster dimensions of the spindle units to be kept very small, which in turn allows the spindle units to be packed very tightly on the machining head.
In order to create a simple mounting for the drive motor in the module housing so that it is rotationally fixed and at the same time axially displaceable, the drive motor housing may be furnished with at least two apertures, through which the at least two rod axles extend. In this simple way, an axial mounting is provided for the drive motor housing in the module housing, wherein the drive motor may be braced on the module housing and at the same time is also axially displaceable within the module housing.
When manufacturing multi-spindle machining heads, it is often necessary for the drive spindles to be provided in pairs or in multiple combinations. In order to be able to realize these multi-spindle machining head constructions, in which several drive spindles together form a common group, in a simple manner, it is particularly advantageous if a spindle unit includes several drive spindles, particularly two or four drive spindles, each having an allocated drive motor and each having an allocated axial actuating device. In this way, the spindle unit forms an integrated modular component that includes several drive spindles. These integrated modular components in turn may then be preassembled and tested in advance, and then combined simply to form multi-spindle machining heads.
In order for a multi-spindle machining head to be operated properly, it is very important for the drive spindle to be controlled precisely, otherwise it is not possible to ensure that the tool is positioned correctly relative to the machining location on the work piece, for example in order to make a drill hole. To provide a simple means for realizing this, it is particularly advantageous if a bearing sleeve is fixed to the drive motor, in which bearing sleeve the drive spindle is mounted so as to be able to rotate freely and/or is axially immovable. In this way, the drive motor and the mounting for the drive spindle in the bearing sleeve form a mechanically connected unit, thereby completely preventing any dimensional deviations between the drive motor and the drive spindle mounting. This is particularly important with respect to the spindle unit according to the invention because the drive motor is axially displaceable together with the axial spindle.
In this context, the bearing sleeve for mounting the drive spindle may serve at the same time as the mounting for the rotor of the drive motor, and a separate mounting for the rotor of the drive motor may be dispensed with. This construction is particularly advantageous if the rotor of the drive motor and the drive spindle are connected to each other as a single part, for example by use of a through-axle.
In order to prevent the tool that is in engagement from becoming misaligned relative to the unit center axis, the case plate of the module housing may be furnished with an aperture. The bearing sleeve passes through this aperture in the case plate and braces the case plate so that the bearing sleeve cannot be forced to one side.
The bearing sleeve is retained in the aperture in the case plate particularly precisely if the aperture forms a push-fit system. In other words, this means that the aperture then forms a slide bearing for the bearing sleeve, in which the bearing sleeve is axially displaceable. The center axis of the bearing sleeve is centered radially on the center axis of the unit.
When a tool is fixed on the spindle unit and is in engagement with a work piece, the axial forces that must be applied in the machining zone are often very great, for example when a drill is used to drill a hole. In order to be able to absorb these strong axial forces with the axially displaceable drive spindle in a simple manner on the module housing, it is particularly advantageous if the bearing sleeve is furnished with a locating groove. A bolt of a locking device may then engage in positive locking manner in the locating groove and thus secure the bearing sleeve axially to the module housing. Locking the axially displaceable part to the module housing in particular also relieves the stress on the axial actuating device, which no longer has to absorb any axial forces after the locking is in effect. As a result, correspondingly less robust axial actuating devices are required.
A particularly compact and small locking device may be produced if locking and unlocking is performed by a magnetic actuating device.
It is also particularly advantageous if the locking device is arranged on the outside of the module housing, particularly on the outside of the case plate that holds the bearing sleeve in place axially. In this way, no additional installation space is required between the spindle units, so the maximum packing density of the spindle units on the multi-spindle machining head is not limited.
The axial actuating device should preferably be constructed in the form of a pneumatic actuating cylinder with axially drivable drive piston.
In this regard, the free end of the piston rod of the drive piston may be attached mechanically to the drive motor housing, to that it is able to axially displace the drive motor and the drive spindle connected thereto.
In order to enable a more compact construction, one preferred embodiment provides that the module housing forms the pneumatic actuating cylinder and the drive motor housing forms the pneumatic drive piston of the spindle unit. In other words, this means that a further step towards functional integration is taken, with the result that the components of the pneumatic axial drive are formed by existing components, that is to say by the module housing and the drive motor housing. The drive motor housing is already suitable to serve as the pneumatic drive piston, since the drive motor housing is regularly cylindrical in shape and may thus easily be sealed in a cylindrical retainer in the module housing. The advantage of this embodiment is that many components that would otherwise be needed to form the pneumatic axial actuating device may thus be dispensed with. A piston rod for transferring the axial propulsion from the drive piston to the drive motor is also not required. Overall, this results in an extremely compact construction.
If the drive piston for the pneumatic axial actuating device is formed by the drive motor housing, the lines for transmitting drive energy between the module housing and the drive motor should be routed through the pneumatic actuating cylinder.
In order to prevent the rotationally driven drive motor from spinning relative to the module housing that forms the pneumatic actuating cylinder, a combination of a support groove and a support element acting in positive locking manner may serve to brace against torque instead of using guide rods. In this case, the support groove is machined into the cylindrical piston area of the pneumatic actuating cylinder so that the support element attached to the drive motor housing is able to engage in positive locking manner in the support groove to brace against torque. This integration of the torque bracing in the actuating cylinder of the pneumatic axial actuating device enables an even more compact construction, since in particular the guide rods may be dispensed with.
In order to create the most compact construction possible, it is particularly advantageous if the pneumatic control unit for positioning the drive piston in the actuating cylinder is arranged on the rear end of the module housing. In this context, prismatic or cylindrical cross sections of the control unit should align with the prismatic or cylindrical cross section of the module housing, such that when several spindle units are arranged one beside the other there are no overlaps on the individual spindle units, and it is thus possible to pack the spindle elements very closely together.
The spindle unit drive motor is preferably designed as a type of variable servomotor with sensor equipment. In particular, it is advantageous if the direction of rotation of the spindle unit is freely selectable, so that the direction of rotation may be determined for each individual tool on the multi-spindle machining head independently of the other tools. Information for describing the machining operation may also be collected and uploaded with sensor equipment appropriate for the purpose. In this way, it is possible, for example, to detect a tool failure or wear of the tool on the spindle unit and respond accordingly. In particular, a positional sensor means also makes it possible to position each tool individually on the multi-spindle machining head, without reference to the other tools, so that a tool may be changed.
In order to increase functional integration yet further, the electronic controller of the servomotor may be fixed to the allocated module housing, Alternatively, it is also conceivable to connect the controller to the servomotor via a cable and locate it somewhere else entirely.
A module housing carrier may be provided so that multiple spindle units may be fixed in the correct position on the multi-spindle machining head. The individual spindle units are secured exactly in position on the module housing carrier one at a time and independently of the other spindle units, which in turn prevents the accumulation of positional errors, such as occur when the individual spindle units are secured to each other.
In order to position the spindle units as exactly as possible on the module housing carrier, an aperture may be provided on the module housing carrier for each spindle unit. The bearing sleeve of the drive spindle then passes through this aperture to form a push-fit system, in which the bearing sleeve is axially displaceable. In this way, an exact radial positioning of the unit center axis is ensured by the position of the apertures in the module housing carrier. Each individual unit center axis is then positioned and centered independently of the other spindle units on the module housing carrier.
In order to enable the spindle units to be attached to the module housing in simple manner at least two apertures may be provided on the module housing carrier for each spindle unit. The ends of the module housing rod axles are then located in these apertures.
It is particularly advantageous if in embodiments of the module housing that have two rod axles for each spindle unit in the module housing carrier, four apertures are provided for attaching the rod axles. In this case, these four apertures should preferably be arranged at the corners of a square. In this way, the spindle unit may be attached with its two rod axles to the module housing carrier in various relative positions, since each rod axle may be attached diagonally offset in the four apertures.
In order to further increase the degree of modularity, the module housing carrier may also be constructed from a number of standardized module components. Module housing carriers that are created modularly from a module construction system in this way may be used for fabricating multi-spindle machining heads quite generally and regardless of the construction of the spindle units, since standardized modular components may be used to create module housing carriers in a wide variety of geometric shapes, and using a small number of non-variable parts is favorable for inexpensive, uncomplicated production. By using standardized module components, it is thus possible to define the geometric shape of the machining head first, by carefully combining module components so as to avoid manufacturing order-specific, complex single parts in order to produce the housing carrier that supports the spindle units.
Standardized plate elements in particular are most suitable for creating such a module construction system. Even with just a few such standardized plate elements, to which two, three, four or more spindle units may be attached, it is possible to form multi-spindle machining heads with practically any geometry. To this end, the individual plate elements are combined in at least two layers in accordance with the desired geometry, the individual plate elements in each respective adjacent layer being arranged in overlapping manner to form a mechanically solid transition between the individual plate elements. Then, the plate elements of the module housing carrier are attached in fixed manner to each other, for example glued together. Accordingly, a wide variety of geometries may be created for the multi-spindle machining heads from a small number or standardized module components.
According to a further aspect of the invention, a tool carrier is arranged at least on one spindle unit of the machining head, which tool carrier includes its own drive motor so that it is able to drive a separate drive spindle in rotary manner. In other words, this means that the spindle unit essentially only serves to displace the tool carrier axially, whereas the drive motor in the tool carrier is tasked with the rotary drive of the tool. This enables a wide range of functions to be performed, for example horizontal drilling, milling, sawing.
The drive motor may be removed, that is to say dismounted or omitted, on spindle units that have a tool carrier that has its own drive motor, since it is often not necessary for the tool carrier to be driven rotationally. Tool carriers that are equipped with their own drive motor may be used for creating multi-spindle machining heads quite generally and independently of the spindle unit configuration. This particularly makes is possible to integrate complex production functions, for example swiveling C-axes, in conventional spindle arrays, particularly vertical drill spindle arrays. Thus for example, special designs for these complex production functions may be avoided. Equally, the spindle unit may also be used as a stand-alone unit, in the case of separate universal processing machines for example.
It is particularly advantageous if the drive spindle in the tool carrier is at right angles to the drive spindle of the spindle unit in the machining head. In particular, this enables horizontal drilling, horizontal milling, or circular saw functions to be carried out.
If the tool carrier is swivelable about a swivel axis of a spindle unit, the function of the swivel drive may be performed by the rotary drive of one of the drive spindles in the machining head.
Various embodiments of the invention are shown schematically in the drawing and will be explained in the following for exemplary purposes.
In the drawing:
A spirally coiled supply cable 13, which is wound round piston rod 05, serves to supply drive motor 03 with electrical energy and also to enable data to be exchanged between the controller and drive motor 03, which is configured as a servomotor with sensor equipment. Because of its elasticity, supply cable 13 is able to compensate for the longitudinal change in position of drive motor 03 relative to module housing 08, and is also held in position by piston rod 06.
Rotor axle 17 is integrally connected to drive spindle 02, and a tool attachment module 02a is provided on the free end of drive spindle 02 for mechanically connecting a tool, for example a drill, to the drive spindle.
Roller bearings 20 and 21 ensure that drive spindle 02 and rotor axle 17 are mounted so as to be movable in rotary manner and axially fixed relative to bearing sleeve 04, which is fixed to the bottom end of housing 19 of drive motor 03. Bearing sleeve 04 passes through lower case plate 10 in an aperture with surface tolerance. The surface tolerance of the internal diameter of the aperture in case plate 10 and of the external diameter of bearing sleeve 04 is selected in the manner of a slide bearing, such that a push-fit system is created. In this push-fit system, bearing sleeve 04 may be displaced axially through case plate 10, while unit center axis 07 is radially centered.
A locating groove 22 is machined into the middle of the outer side of bearing sleeve 04 and protrudes beyond module housing 08 when bearing sleeve 04 is extended axially. This locating groove serves to axially secure the axially movable parts of spindle unit 01.
Each of drive spindles 02 is in turn mounted so as to be rotatable and free of axial play, and is drivable with its own drive motor 03 and may be axially displaced by an axial actuating device 05. Module housing 31 of spindle unit 30 is formed by an upper case plate 32, a lower case plate 33 and four rod axles 34, which are arranged in pairs. The axially displaceable mounting of drive motors 03 on rod axles 34 is equivalent in principle to spindle unit 01. Case plate 33 is furnished with two apertures, equal to the number of bearing sleeves 04, forming a push-fit system for each bearing sleeve 04. Otherwise, the construction of spindle unit 30 follows the same principle as that of spindle unit 01.
A module housing carrier may be used for positioning spindle units 01 or 30 relative to each other. A module housing carrier 35 of such kind for creating a multi-spindle machining head 36 is illustrated for exemplary purposes in
The geometry of the drilling pattern for the multi-spindle machining head to be created is determined by the geometry of module housing carrier 38. Standardized module components are suggested that will enable a large number of module housing carrier geometries to be produced with standardized, prefabricated components.
To build module housing carrier 38, two plate elements 42 and one plate element 43 are laid out as in a T-shape as the first layer on a jig. Then, a second layer, including two plate elements 41, a corner plate element 44, and one plate element 42, are laid on top of the first layer with the same geometry. The end faces of the plate elements overlap in both layers. The jig that is used preferably has aligning bolts with dimensional tolerances, on which the plate elements are placed using apertures 39, to ensure that the plate elements are aligned relative to each other and dimensions are retained.
The two layers are then bonded to each other mechanically, for example by adhesion. In this way, a very large variety of module housing carriers with differing dimensions and geometries may be created from standardized module components 41 to 44.
In addition, four spindle units are shown, the drive spindles of which are attached to tool carriers 51, 52 and 53. Tool carriers 51, 52 and 53 are each equipped with their own drive motor and are independent of the rotary drive in spindle units 01 and 30. The spindle units 30a that are assigned to tool carriers 51, 52 and 53 are only used for axial displacement and for connecting tool carriers 51, 52 and 53 to the respectively assigned electronic controllers 50, therefore they do not have their own drive motor.
Tool carrier 52 (see
Three axial actuating devices 05 are provided for positioning tool carrier 53 axially. Tool carrier 53 may be rotated through 360 degrees about unit center axis 55. A drive motor 03 is used as the slewing drive for swiveling tool carrier 53, the drive spindle 02 of which drive motor engages via a gearing 56 with slewing gear 63 that is arrestable by a clamping device 64 and is fixed to tool carrier 53. The clamping device is in the form of a conical brake flange and is actuated by the non-rotating piston. In addition, a position sensor 65 is provided inside slewing gear 63 to monitor the slewing angle of tool carrier 53.
The electrical connection between drive motor 66 in tool carrier 53 and position sensor 65 in slewing gear 63 is assured by spirally wound connecting cables 57 and 58, which are longer than connection cable 13 with which drive motor 03 in spindle unit 54 is connected.
One spirally wound line 75, only indicated in
In order to provide torque support for drive motor 68 against module housing 69, a bracing element 76 is attached to the rear extremity of drive motor 68, extends radially slightly beyond the cylindrical periphery of housing 70 of drive motor 68, and engages in a support groove 77 in the piston bearing surface 78 of both pneumatic actuating cylinders 72 and 73. The slight radial protrusion by bracing element 76 with respect to housing 70 is particularly visible in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2007-038-462.0 | Aug 2007 | DE | national |
| 10-2008-035-523.2 | Jul 2008 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DE08/01323 | 8/14/2008 | WO | 00 | 2/11/2010 |
