DE20022978U1 - Positioning unit with display device - Google Patents

Description

Positioning unit with display device

The invention relates to a positioning unit for the automatic positioning of a shaft, which has an adjusting device for setting or adjusting the position of the shaft and an absolute electrical measuring system for detecting and controlling the position of the shaft over the entire rotation angle range of the shaft.

Such a positioning unit is a device for positioning a shaft that is used in the positioning of so-called setting axes of machines, which are also referred to as machine axes. These setting or machine axes are adjustment or feed axes with which, for example, tools can be moved into a working position. In this case, a machine slide, on which, for example, a tool is arranged, is moved on a machine via a threaded spindle.

The positioning unit has a shaft, which can be designed as a hollow shaft or a solid shaft, and is connected to the machine axis to be adjusted in a form-fitting and/or force-fitting manner.

In particular, positioning units, i.e. devices for positioning a shaft, are used in machining and processing machines where the necessary tools, such as e.g.

Sawing, drilling or grinding equipment, as well as equipment for applying glue, veneer, surface coatings, etc., must be moved into defined positions depending on the dimensions of the object to be manufactured or processed. These processing machines are used in the manufacturing industry, for example in

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Heavy use in woodworking and wood processing machines.

For example, when manufacturing furniture, a large number of furniture parts, each with different dimensions, must be manufactured. The various furniture parts are regularly cut, milled, sanded, drilled, etc. on a woodworking machine. This means that the woodworking machine must be set to different dimensions to produce each piece of furniture.

The adjustment of the woodworking machines to the desired dimensions has so far been carried out mainly by hand using the adjustment axes mentioned above.

A positioning unit for automatically positioning a shaft over the entire rotation angle range of the shaft is known from DE 197 03 525.6. The positioning unit known from DE 197 03 525.5 allows highly precise positioning of a shaft over the entire rotation angle range of the shaft. The measuring system integrated in the aforementioned positioning unit can be both incremental and absolute.
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The measuring range of these measuring systems usually covers an angular range of several revolutions of the shaft, for example one hundred 360° revolutions of the shaft.

A disadvantage of this known positioning unit is that in the event of an interruption in operation, which is due, for example, to damage to the positioning unit, the information about the exact position of the shaft is lost or can no longer be read due to damage to the data transmission unit.

In an absolute measurement, a unique numerical value is available within the measuring range for each position of the shaft.

If the positioning unit is damaged and requires the defective positioning unit to be replaced with a functioning one, the position value indicating the exact position of the shaft is no longer known.

In this case, the machine axis must be moved to a clearly defined and known reference position before the defective positioning unit is replaced with a functioning one, so that the electrical measuring system of the functioning positioning unit can be set to the reference value assigned to this reference position. A position is usually selected as the reference position in which the machine axis is in an end position. The positioning unit and thus its internal measuring system must then be set to this reference value assigned to the end position, for example zero. The setting can only be made electrically via a data interface, e.g. a CAN bus interface.

If an incremental measuring method is used with the measured value stored in a non-volatile memory, an additional problem arises if the machine is adjusted while the power is off. The position value of the shaft stored in the electrical measuring system of the positioning unit then deviates from the actual position of the shaft. In this respect, the electrical measuring system must be readjusted here too, in which the machine axis must be moved to a reference position and the positioning unit must be set to the reference value assigned to this reference position.

A disadvantage of the known positioning unit is that if the information about the exact position of the shaft is lost, a complex adjustment procedure, as described above, must be carried out.

Furthermore, in the event of a failure of the positioning unit, the adjusting device for adjusting the machine axis

be affected, so that the machine axis must be moved manually to a corresponding reference position before a functional positioning unit is installed. This is complex and usually requires additional means that allow the machine axis to be adjusted manually.
5

The situation is even more disadvantageous if the positioning unit fails during operation of the processing machine. In such a case, it may be impossible to move the machine axis to a reference position because a tool, such as a circular saw, is still in engagement with the object being processed. Moving the machine axis to the reference position would then lead to damage to the tool and/or the object being processed.

In such a case, extensive repair work is required, in which the machining or processing machine must be dismantled to such an extent that the tool in use or the object being machined can be removed so that the machine axis can then be moved to the reference position. The defective positioning unit can then be replaced with a functional positioning unit.

In principle, it is possible to output the exact position from an internal absolute measuring system or, in the case of an incremental measuring system, from an electronic memory, for example a non-volatile memory, of the defective positioning unit. However, if the electrical reading of the exact position is no longer possible due to the damage, for example if the data bus or the measuring system fails, the machine axis must first be moved to a reference position before the functional positioning unit is installed. However, as explained above, this is very complex.

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From DE 34 19 499 C2 a measuring sensor for detecting the position of a drive element of a tool or workpiece is known, which has a counter with a mechanical counter and a control pulse generator for generating electrical control pulses as an actual position sensor. The mechanical counter and the control pulse generator are rigidly coupled to one another and have a coupling shaft that belongs to a detachable coupling.

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The object of the present invention is therefore to provide a positioning unit which does not have the disadvantages listed above. The object is therefore in particular to provide a positioning unit which enables a simple and reliable exchange of a positioning unit in any position of a machine axis.

The object underlying the invention is achieved by providing a positioning unit according to claim 1. Preferred developments are specified in the dependent claims 2 to 18.

In the present invention, a positioning unit can be used for the automatic positioning of a shaft, which has an adjusting device for setting the position of the shaft and an absolute electrical or electronic measuring system for detecting and regulating the position of the shaft over the entire rotation angle range of the shaft, wherein the positioning unit additionally has a mechanical device for detecting and displaying the position of the shaft and wherein the electrical measuring system and the mechanical device can be adjusted to one another with regard to detecting the position of the shaft.

The actuating device may comprise an actuator such as an electric motor, in particular a stepper motor, which is connected to the shaft in a conventional manner, for example via belts, toothed belts, friction disks, coupling, flange, one or more gears or one or more gear groups.

The measuring system known from DE 197 03 525.6 can be used as an electrical measuring system. This measuring system allows the position of the shaft to be recorded and controlled. A position value of the shaft is entered into the positioning unit as a target value, after which the adjusting device performs an adjustment.

the shaft or adjusting the shaft to the desired position.

Within the measuring range, for example, each position of the shaft is assigned a unique numerical value. The position of the shaft can be defined by the number of complete or partial revolutions of the shaft. The assigned numerical value can, for example, be based on the number of complete and/or partial revolutions of the shaft and the pitch of a thread on the shaft that is used to adjust the associated machine axis. Of course, other ways of assigning numerical values to the position of the shaft are also possible, for example when the machine axis is adjusted using a rack and pinion combination. The measuring system is an absolute measuring system. The measuring system integrated in the positioning unit is an absolute measuring system.

The positioning unit according to the invention also has means for fastening the positioning unit to a machine axis to be positioned. These means can be designed in different ways. For example, the positioning unit according to the invention can have a shaft in the form of a hollow shaft that can be pushed onto a machine axis. The hollow shaft can then be connected to the machine axis in a force-fitting manner, for example via a clamping ring arranged on the hollow shaft. Of course, the shaft designed as a hollow shaft can also be connected to the machine axis in a form-fitting and/or force-fitting manner using other means.

If the shaft is designed as a solid shaft or massive shaft, the positioning unit according to the invention can be connected to the machine axis via a coupling, flange, etc.

The devices to be adjusted on the processing machine, such as drills, saws, planers, milling machines, grinding devices, spacers, devices for applying glue, veneer or varnish, etc., are then adjusted or set via the machine axis.

In the positioning unit according to the invention for automatically positioning a shaft, a mechanical device is also provided which detects and displays the position of the shaft. It is important that the mechanical device and the electrical measuring system can be or are calibrated to one another so that the position of the shaft detected by the electrical measuring system and the position of the shaft detected by the mechanical device are clearly related to one another. Ideally, the position value detected by the electrical measuring system and the position value detected and output by the mechanical device are identical.

In the event of damage or failure of a positioning unit arranged in a processing machine, the exact position of the shaft on the mechanical device can be read regardless of the type of damage to the positioning unit.

The functional positioning unit that is to be replaced with a defective positioning unit can be set to the corresponding position value manually or using the electrical adjustment device in the positioning unit. The mechanical display then naturally shows the corresponding position value. This position value is also measured by the electrical measuring system.

The defective positioning unit is then replaced with a functional positioning unit set to the same position value. This means that the processing machine can be started up immediately after the replacement of the

The defective positioning unit can be replaced with a functioning positioning unit.

This is particularly advantageous if the processing machine was in a processing state when the damage occurred, in which a workpiece or object was being processed. This object can then be further processed without being removed from the processing machine, as the previously required adjustment, i.e. moving the machine axis to a reference position, is no longer necessary.

The downtime of the processing machine is thereby significantly reduced. In this respect, the present invention enables a considerable reduction in costs and an increase in productivity, which can be attributed to the shortened downtime of the machine.

Furthermore, any maintenance personnel can replace a defective positioning unit with a functional positioning unit. The previously time-consuming process of replacing a defective positioning unit with a functional positioning unit, which had to be carried out by specially trained personnel because the machining or processing machine had to be partially dismantled and the machine axis moved to the reference position, is no longer necessary.

According to an advantageous development, the mechanical device for displaying the position is integrated in the positioning unit.

In the processing machines, a large number of positioning units for the automatic positioning of a machine axis are often arranged in close proximity to one another, so that the positioning units must be designed compactly. In this respect, it is preferred that the mechanical device is arranged integrated in the positioning unit.

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Regardless of this, a miniaturization of these positioning units is also desired by the manufacturers of the processing machines in order to be able to make the processing machines more compact overall.

It is preferred that the electrical measuring system and the mechanical device for detecting the position of the shaft are mechanically coupled to the actuating device via one or more transmission means.

If the electrical measuring system and the mechanical device are mechanically coupled to the adjusting device, any change in the position of the shaft or any adjustment of the shaft is picked up directly at the shaft and transmitted to the electrical measuring system or the mechanical device.

In particular, it is preferred that a gear is arranged between the actuator, such as an electric motor, in particular a stepper motor, and the shaft. This gear transmits the rotary motion exerted by the motor to the shaft. Additional transmission means can be engaged with this gear, whereby the change in position of the shaft is transmitted to the electrical measuring system on the one hand and to the mechanical device on the other. Toothed belts, friction disks, gears, worm gears, couplings, etc. can be used as transmission means, for example.

It is preferred that the electrical measuring system and the mechanical device for detecting the position of the shaft are mechanically coupled to the shaft via one or more transmission means.

This means that a gear is preferably arranged on the shaft, with which the transmission means are in engagement. Since the transmission means, preferably gears, are in direct engagement with the shaft, the

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The actual position of the shaft is shown precisely. Of course, the shaft can also be provided with a thread with which the transmission means engage.

In the positioning unit according to the invention, a change in the position of the shaft, which is due to an adjustment of the machine axis in the de-energized state, is also reliably detected and displayed in an extremely advantageous manner.

It is preferred that the transmission means is a gear. A gear designed like an intermediate gear can be provided for the electrical measuring system and the mechanical device. Of course, it is also possible that only one of these intermediate gears is provided, via which the position change is transmitted to the electrical measuring system and to the mechanical device at the same time. For design reasons, however, it may be preferred that the position change of the shaft is transmitted to the electrical measuring system or to the mechanical device by a separate intermediate gear.

The mechanical coupling of the electrical measuring system and the mechanical device with the adjusting device allows the exact position of the shaft to be read on the display of the mechanical device before replacing a defective positioning unit on a processing machine. The functional positioning unit is then set electrically via the adjusting device or manually to the position value of the defective positioning unit. Due to the coupling of the mechanical device and the electrical measuring system with the adjusting device or preferably with the shaft of the positioning unit, the electrical measuring system is automatically set to the correct position value. In this respect, after replacing a defective with a functional one,

Positioning unit the processing machine can immediately resume the processing process.

When manufacturing the electrical measuring system, assembly tolerances may have to be taken into account for the components used, in particular the reference signal generator and the elementary sensor used, for example a potentiometer. On the other hand, tolerances may also occur when assembling the mechanical transmission means, i.e. in particular the intermediate gears used, with regard to a precisely defined reference position.

From a manufacturing point of view, an exact alignment of the electrical measuring system and the mechanical device is difficult or complex.

According to a preferred development of the invention, the electrical measuring device and the mechanical device can be adjusted by positioning the shaft in a reference position, wherein a reference value assigned to this reference position of the shaft can be entered into a memory of the positioning unit and the display of the mechanical device can be set to this reference value.

In the simplest case, this reference position is an end position of the machine axis. For example, the reference or position value zero or 100 can be assigned to this reference position. Of course, any other value can also be selected as the reference value.

It is essential that both the electrical measuring system and the display of the mechanical device can be set to this reference value. As already explained above, the mechanical display and the electrical measuring system do not have to show an identical value. If the values for a certain position of the shaft differ from each other,

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however, they are clearly related to one another. Preferably, however, the position value indicated by the electrical measuring system and the position value indicated by the mechanical device are identical.

The positioning unit and thus its electrical measuring device can be set to the reference value by entering the corresponding position value, e.g. via an electrical interface, e.g. a CAN bus.

An essential feature of the positioning unit according to the invention is that the mechanical device can be adjusted exactly to a selected reference value.

In the positioning unit according to the invention, it is necessary, in view of the accuracy required in practice, that the electrical measuring system and the mechanical device can be or are precisely calibrated to a reference position. In the sense of the invention, this can be done by entering a reference value for the electrical measuring system and setting the display of the mechanical device to this reference value after mounting the positioning unit.

In this advantageous development of the invention, the assembly tolerances of the mechanical and electromechanical components of the electrical measuring system used are compensated, i.e. rendered ineffective. This means that when the positioning unit according to the invention is assembled, the display of the mechanical device is set precisely to the specified reference value, and thus the electrical measuring system and the mechanical device are precisely aligned with one another.

This procedure eliminates the need for time-consuming adjustment of the electrical measuring system and the mechanical device, since the tolerances that occur during the manufacture of the individual components are compensated for by the
subsequent

Adjusting the mechanical device to exactly match the reference value.

In a further preferred embodiment, the mechanical device outputs the detected position of the shaft via a counter which is coupled to the actuating device or preferably to the shaft via one or more transmission means, in particular one or more gears.

The counter can be a display device comprising several, i.e. at least two, number drums that display the total number of complete revolutions of the shaft as well as the partial revolutions of the shaft. Each number drum is provided with whole natural numbers 0, 1, 2, 3, ..., for example. The numbers can be applied to the outer surface of the roller in a conventional manner.

In view of the desired compact design of the positioning unit, however, it may be desirable for the mechanical device to be designed in such a way that it takes up only a small amount of space in the positioning unit according to the invention. In order to be able to take this additional requirement into account, the number drums can be arranged next to one another in such a way that the roller surfaces of the individual number drums face one another, i.e. the viewer of the mechanical display looks at one of the front sides of the number drums. The digits indicating the roller position are then arranged on one front side of the roller drums. The aforementioned design enables a flat design of the mechanical device for indicating the position of the shaft. The mechanical device preferably comprises two number drums.

With regard to the possibility of balancing the electrical measuring system and the mechanical device, the mechanical display is designed in such a way that, for example, the range within one complete revolution of the shaft

Number drum can be adjusted exactly to the assigned reference value.

Furthermore, it is preferred that the mechanical device outputs the detected position of the shaft via a scale indicating the number of complete revolutions of the shaft and a scale indicating the position of the shaft within a complete revolution of the shaft, wherein the scales are coupled to the actuating device or preferably to the shaft via one or more transmission means, in particular one or more gears.

It is particularly preferred that the scales are designed as disks, preferably as flat disks.

The position values indicating the position of the shaft can be plotted along the circumference of the disks.
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In this development of the positioning unit according to the invention, disks are used to indicate the position of the shaft instead of number drums.

Depending on the number of disks used as scales and the gear ratios of the transmission means driving the disks, preferably gears, the position of the shaft can be indicated very precisely. Preferably two flat disks are used as scales. The use of circular scale disks in particular enables a very flat and compact design of the mechanical device for detecting the position of the shaft. The disks can easily be arranged on the inside of a housing surrounding the positioning unit. Openings, which may be covered with a transparent material such as glass or plastic, can then be provided for reading the position of the shaft. The transparent material can be designed like an optical lens so that the displayed

Numerical values are optically enlarged. This makes it easier and more accurate to read the scales.

Furthermore, it is preferred that a scale for indicating the number of complete revolutions of the shaft is coupled to the adjusting device or preferably to the shaft via one or more transmission means, in particular one or more gears, and that a scale for indicating the position of the shaft within a complete revolution of the shaft is fixed relative to the shaft and substantially concentric to the shaft and a pointer can be arranged on the shaft so as to be fixable substantially at right angles to the longitudinal axis of the shaft.

This embodiment enables a particularly compact design of the positioning unit according to the invention, since the mechanical device for detecting and displaying the position of the shaft is reduced to very few components and is therefore designed to be extremely space-saving.

In this embodiment, a scale is used, which is preferably a disk and on whose outer circumference the position values indicating the position of the shaft, i.e. the number of complete revolutions of the shaft, are plotted, for example whole numbers in a range between 0 to 500, 0 to 400, 0 to 300, 0 to 200 or 0 to 100. Of course, other number ranges can also be plotted on the scale.

This scale, which indicates the complete revolutions of the shaft, is mechanically coupled to the adjusting device or preferably to the shaft via one or more transmission means. The transmission means is preferably a gear that has a suitable reduction ratio in order to indicate the adjustment of the shaft caused by the adjusting device in terms of complete revolutions of the shaft.

• · ♦ ·

In this embodiment, the partial rotation of the shaft is indicated by a pointer arranged on the shaft and pointing to a scale that is fixed in position with respect to the shaft and arranged essentially concentrically to the shaft. This means that the pointer rotates with the shaft and shows the corresponding position value of the shaft within a complete rotation on the scale arranged around the shaft. In this embodiment, the scale is, for example, a perforated disk. The shaft is then guided through the scale designed as a perforated disk. The pointer is arranged on the shaft in such a way that it points to the scale applied along the circumference of the perforated disk.

Depending on the scale of the scale, which is fixed in relation to the shaft, the position can be displayed very precisely within one complete revolution of the shaft. When using a scale with 90 divisions, the position is displayed to within 4°, with 180 divisions to within 2°, with 360 divisions to within 1°, with 100 divisions to within 3.6° and with 1000 divisions to within 0.36° within one complete revolution of the shaft. Of course, any other scale with a larger or finer scale can also be selected. The accuracy of this scale ultimately depends on the accuracy of the display of the shaft position required in the field of work in question.

In this embodiment of the positioning unit according to the invention, in the best case only one transmission means is required, i.e. in particular a gear that mechanically couples the scale indicating the complete revolutions of the shaft to the adjusting device or preferably to the shaft.

It is extremely advantageous in this development according to the invention that no additional transmission means such as a gear are required to display the position of the shaft within a complete revolution.

required. This allows an extremely space-saving and compact design of the positioning unit according to the invention.

Thus, using this embodiment, an extremely compact positioning unit for automatically positioning a shaft can be provided.

In this embodiment, the pointer is further designed in such a way that it can be fixed to the shaft.

In this way, a particularly simple adjustment of the electrical measuring system and the mechanical device with regard to the detection of the position of the shaft is possible. After the positioning unit according to the invention has been manufactured, the electrical measuring system is set to the reference value, for example zero, and then the pointer for displaying the position of the shaft within a complete revolution is set to zero.

This ensures that the electrical measuring system and the mechanical device are set exactly to the reference value, in this case zero, for example. This means that assembly tolerances in the electrical measuring system used and also deviations from the reference value that occur during manufacture of the positioning unit, i.e. when installing the mechanical device for detecting the position of the shaft, can be compensated.

These deviations are usually within one complete revolution of the shaft. Therefore, if the scale showing the complete revolutions of the shaft is set to the reference value, in this case zero, for example, the scale showing the position value within one complete revolution of the shaft can be precisely adjusted to the reference value entered into the electrical measuring system by subsequently setting the pointer to the reference value, i.e. zero in this case.

The scale that indicates the complete revolutions of the shaft can be designed, for example, as a gear with a scale disk attached. This gear is then coupled to the adjusting device or preferably to the shaft via mechanical transmission means, i.e., for example, via one or more gears. When setting the reference value, i.e., the number of complete revolutions of the shaft, the positioning unit is positioned to the reference value entered into the positioning unit using the adjusting device. The scale disk is then arranged on the gear so that the specified reference value, i.e., the specified number of complete revolutions, is precisely displayed on the scale disk. The scale disk can be glued to the gear, for example, or mechanically fixed.

As described in DE 197 03 525 A1, which is hereby incorporated by reference, the positioning unit specified therein has a coarse rotary encoder, a reference signal encoder and a fine rotary encoder. In particular, the assembly of the reference rotary encoder and coarse rotary encoder is subject to unavoidable mechanical tolerances, which have no influence in purely electrical operation, but which make the adjustment between the electrical measuring system and a mechanical display more difficult. For this reason, during final assembly and final testing of the positioning unit according to the invention, the pointer indicating the position within a complete rotation of the shaft is preferably designed to be fixable on the shaft, whereby the display of the mechanical device is first set exactly to the reference value by means of the pointer and then the pointer is fixed to the shaft.

The present positioning unit according to the invention for the automatic positioning of a shaft thus enables an exact adjustment of the electrical measuring system and the mechanical

Display for detecting and displaying the position of the shaft. Furthermore, this design of the mechanical device allows, in addition to the above-mentioned precise adjustment of the electrical measuring system and the mechanical device, an extremely space-saving arrangement of the mechanical device within the positioning unit according to the invention, since in the best case only an additional gear is required, which couples the display outputting the complete revolutions of the shaft to the actuating device or preferably to the shaft.

According to a further preferred embodiment, the pointer can be secured to the shaft via fastening means that can be attached to the shaft. The securing is preferably carried out in a form-fitting manner.

It is preferred that the fastening means is a fastening ring with an inner diameter corresponding to the outer diameter of the shaft, wherein the fastening ring has at least one projection pointing in the direction of the ring opening, preferably at least two projections pointing in the direction of the ring opening, which engage(s) in recesses provided in the shaft. Preferably, the projection pointing into the ring opening is arranged in a substantially radial direction.

The fastening ring can thus be pushed onto the shaft and has at least one, preferably at least two projections, which point essentially radially in the direction of the ring opening of the fastening ring. These projections then engage in recesses provided in the shaft. The projections can have any geometric shape, i.e. they can be semicircular, angular or undercut, for example. The recess provided in the shaft must be designed in accordance with the geometric shape of the projections of the fastening ring.

When using an output shaft designed as a hollow shaft, the recesses are preferably designed as continuous grooves or slots, which are arranged on the shaft, for example, offset from one another by 90° along the circumference of the shaft in the axial direction. The arrangement of the slots allows the hollow shaft to be positively secured to the machine axis after the positioning unit has been pushed onto the spindle of a machine axis.

The projections are then inserted into the recesses in the shaft when the fastening ring is assembled and the fastening ring is then pushed onto the shaft. Furthermore, a stop can be provided on the shaft up to which the fastening ring can be pushed. Finally, locking means can be provided in the recesses in the shaft so that the projections on the fastening ring can be locked into the recesses in the shaft. The fastening ring can thus be attached to the shaft in a simple manner.

Of course, the fastening ring can also be only partially formed, ie for example as a three-quarter circle or a semicircle. It is important that the fastening ring can be fixed to the shaft. The pointer can then be attached to this fastening ring, for example by gluing, welding, soldering, screwing, riveting or by snapping it into place.
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According to a further preferred embodiment, the fastening ring is designed like an annular disk and has at least one opening, preferably at least two openings, in the annular disk area.

In the present case, an annular disk is understood to mean a disk with a central opening in the manner of a washer. At least one opening, preferably at least two openings, is then provided in the annular disk area. These openings can be circular or square, for example.

In this development according to the invention, a pointer in the form of a ring disk and then a fastening ring can be pushed onto the shaft. The pointer set to the reference value can then be fixed to the fastening ring fixed to the shaft by means of the openings provided in the fastening ring in the form of a ring disk, for example by gluing, welding, soldering, screwing, riveting, snapping, etc.

This is extremely advantageous as the position of the pointer, which is set to the reference value, is fixed relative to the shaft. When the pointer is dismantled and then reassembled, the adjustment of the mechanical display and the electrical measuring device is not lost. This means that re-adjustment is not necessary.
15

In this embodiment, the pointer is preferably attached to a ring, the opening diameter of the ring corresponding to the diameter of the shaft, so that the pointer can be pushed onto the shaft. For example, a ring disk provided with a projection can be used as the pointer. This projection then serves as the pointer.

According to a further preferred embodiment, the pointer is designed like a ring disk and has at least one opening, preferably at least two openings, in the ring disk.

In this embodiment, a fastening ring is first pushed onto the shaft and then a pointer as described above is pushed onto the shaft. After the pointer has been set to the reference value, the pointer can be connected to the fastening ring fixed to the shaft by means of gluing, soldering, welding, screwing, riveting, snapping, etc. through the openings provided in the ring-shaped pointer.

According to a further preferred embodiment, the scale for indicating the position of the shaft within a complete revolution of the shaft has a

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·

·

Scaling with an accuracy of at least 3.6°, preferably at least 0.36°.

The fineness of the scale is essentially only limited by the optical resolution. The accuracy or fineness of the scale depends on the required processing accuracy of the processing machine.

The present invention thus provides, in a surprisingly simple manner, a positioning unit for automatically positioning a shaft, which has both an electrical measuring system for detecting and controlling the position of the shaft and a mechanical device for detecting and displaying the position of the shaft.

The positioning unit according to the invention allows a defective positioning unit to be easily replaced with a functional positioning unit, whereby a complex adjustment of the processing machine after replacing the positioning unit is no longer necessary. This simplifies the replacement and considerably reduces the downtime of the processing machine.

The positioning unit according to the invention is described below with reference to the figures. The figures merely represent illustrative embodiments of the present invention.

Fig. 1 shows a schematic representation of the

positioning unit according to the invention for
Positioning a shaft;

Fig. 2 shows an embodiment of the inventive
Positioning unit from the front;

Fig. 3 shows the embodiment shown in Fig. 2 in
side view;

Fig. 4 shows a front side of the shaft;

Fig. 5 shows a pointer which is used in the inventive

positioning unit can be used; and

Fig. 6 shows a fastening ring which is used in the

positioning unit according to the invention use
Can be found.

Fig. 1 shows a schematic representation of the positioning unit according to the invention. A shaft (1) is driven by an adjusting device (9). An electrical measuring system (4) for electronic path measurement is coupled to the shaft (1) via an intermediate gear (5). A scale (7) for displaying the complete revolutions of the shaft (1) is coupled to the shaft (1) via an intermediate gear (6). The fixed pointer (8) shows the number of complete revolutions of the shaft (1) on the scale (7). The pointer (8) can be designed as a marking embedded in the housing (not shown) of the positioning unit according to the invention. The position of the shaft (1) within a complete revolution is displayed by the pointer (3), which is arranged on the shaft (1), on the scale (2), which is arranged concentrically to the shaft (1). The adjusting device (9) can be an adjusting gear driven by an electric motor, in particular a stepper motor.

Fig. 1 shows that the electrical measuring system (4) for electronic position measurement and the mechanical device for detecting and displaying the position of the shaft are simultaneously coupled to the shaft (1) via an intermediate gear (5) or (6) respectively.

During the manufacture of the positioning unit according to the invention, the electrical measuring system (4) is adjusted by means of the adjusting device (9) in such a way that it generates a signal that corresponds to a reference value, for example the value zero, and the scale (7) is also adjusted to the reference value zero. Against the background of tolerances caused by manufacturing technology both in the reference transmitter, in the potentiometer used as an elementary sensor, for example, and in the intermediate gears (5) or (6), it may be necessary for the pointer (3) on the scale (2) to be adjusted to the entered value after the positioning unit has been manufactured.

• · t · · · t ♦♦ ·

reference value, for example zero, is to be set. This enables an exact adjustment of the electrical measuring system (4) and the display of the mechanical device consisting of scale (7) and scale (2). After setting the pointer (3) to the reference value, for example zero, the pointer (3) is fixed to the shaft (1).

Fig. 2 shows a top view of the positioning unit according to the invention. The scale (2) surrounding the shaft is applied to the housing (10). The scale (2) can be applied directly to the housing (10), for example by gluing or printing, or can be arranged separately in front of the housing (10) in a fixed position relative to the shaft (1). The pointer (3) is not shown in Fig. 2.

Fig. 3 shows the embodiment shown in Fig. 2 rotated by 90° in a side view. An opening (11) is let into the side wall of the housing (10), through which a scale (7) showing the complete revolutions of the shaft can be read. The number of complete revolutions of the shaft (1) is then shown on the fixed pointer (8) on the scale (7). The positioning unit is connected in a force-locking manner to the spindle of the machine axis to be driven, for example via a clamping ring (12) arranged on the shaft (1). In addition, a projection (13) is provided on the housing, for example in the form of a pin, which prevents the positioning unit from rotating when the shaft (1) rotates. Instead of the clamping ring (12), other types of fastening, such as a coupling or a flange, can also be used if, for example, a solid shaft is used as the shaft instead of a hollow shaft.

Fig. 4 shows a top view of a front side of the shaft (1). Recesses (14) are set into the shaft, for example in the form of slots or grooves. These recesses can also have other geometric shapes and can be undercut, for example.

Fig. 5 shows a pointer (3) designed like a ring disk with a ring opening (18), the inner diameter of which corresponds to the outer diameter of the shaft (1). The pointer (3) can thus be pushed onto the shaft (1).
35

Fig. 6 shows a fastening ring (15) designed like a ring disk with projections (17) pointing radially into the ring opening, which can engage in the recesses (14) of the shaft (1). The geometric shape of the projections (17) corresponds to the geometric shape of the recesses (14) in the shaft (1). Furthermore, openings (16) in the form of circular openings are arranged in the ring disk (15).

When adjusting the mechanical device for detecting and displaying the position of the shaft (1) with the electrical measuring system (4), the pointer (3) is pushed onto the shaft (1) and set to the corresponding reference value, for example zero. The pointer (3) is then secured to the fastening ring (15) which is then pushed onto the shaft (1), the projections (17) of the fastening ring (15) engaging in the recesses (14) in the shaft (1), by connecting the pointer through the openings (16) in the ring-disk-like fastening ring (15), for example by gluing, soldering, welding, screwing, riveting, etc. Since the fastening ring (15) is secured to the shaft (1) via the projections (17) engaging in the recesses (14) of the shaft (1), the pointer (3) is thus secured relative to the shaft via the connection created by the openings (16).

(1) are specified.

The positioning unit according to the invention allows the control and detection of the position of a machine axis with an accuracy of a longitudinal feed of up to 0.5 mm, preferably up to 0.1 mm, more preferably up to at least 0.05 mm, extremely preferably up to at least 0.01 mm.

This means that when a defective positioning unit is replaced with a functioning one, the latter can be adjusted with high precision to the position of the defective positioning unit being replaced. It is no longer necessary to move the machine axes to a reference position when replacing the positioning unit. This makes the replacement much easier and extremely advantageously shortens the downtime of the machining or processing machine.

The positioning unit according to the invention can be used extremely advantageously in woodworking machines or wood processing machines, sheet metal working machines, packaging machines, printing machines, etc.

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List of reference symbols

1 Wave 2 Scale to indicate the position of the shaft within a complete Rotation of the shaft 3 pointer 4 electrical measuring system 5 Intermediate gear 6 Intermediate gear 7 Scale to indicate complete revolutions of the shaft 8th pointer 9 Adjusting device 10 Housing 11 Viewing opening 12 Clamp ring 13 Pin to secure the positioning unit against rotation 14 Recess 15 ring-disk-like fastening ring 16 Opening in the ring disc 17 head Start 18 Ring opening of the ring-disk-like pointer

Claims (18)

1. Positioning unit for the automatic positioning of a shaft ( 1 ), which has an adjusting device ( 9 ) for setting the position of the shaft ( 1 ) and an electrical measuring system ( 4 ) which is absolute over the entire angle of rotation range of the shaft ( 1 ) for detecting and regulating the position of the shaft, wherein the positioning unit additionally has a mechanical device for detecting and displaying the position of the shaft ( 1 ) and wherein the electrical measuring system ( 4 ) and the mechanical device can be adjusted to one another with regard to detecting the position of the shaft ( 1 ). 2. Positioning unit according to claim 1, characterized in that the mechanical device for displaying the position is integrated in the positioning unit. 3. Positioning unit according to claim 1 or 2, characterized in that the electrical measuring system ( 4 ) and the mechanical device for detecting the position of the shaft ( 1 ) are mechanically coupled to the adjusting device ( 9 ) via one or more transmission means ( 5 , 6 ). 4. Positioning unit according to claim 1 or 2, characterized in that the electrical measuring system ( 4 ) and the mechanical device for detecting the position of the shaft ( 1 ) are mechanically coupled to the shaft ( 1 ) via one or more transmission means ( 5 , 6 ). 5. Positioning unit according to claim 3 or 4, characterized in that the transmission means ( 5 , 6 ) is a gear. 6. Positioning unit according to at least one of the preceding claims, characterized in that the electrical measuring device ( 4 ) and the mechanical device can be adjusted by positioning the shaft ( 1 ) in a reference position, wherein a reference value characterizing this reference position of the shaft ( 1 ) can be entered into the positioning unit and the display of the mechanical device can be set to this reference value. 7. Positioning unit according to claim 6, characterized in that the reference position is an end position of the shaft ( 1 ). 8. Positioning unit according to at least one of the preceding claims, characterized in that the mechanical device outputs the detected position of the shaft ( 1 ) via a counter which is coupled to the adjusting device ( 9 ) or the shaft ( 1 ) via one or more transmission means, in particular one or more gears. 9. Positioning unit according to at least one of claims 1 to 7, characterized in that the mechanical device outputs the detected position of the shaft ( 1 ) via a scale ( 7 ) indicating the number of complete revolutions of the shaft and a scale ( 2 ) indicating the position of the shaft ( 1 ) within a complete revolution of the shaft, wherein the scales ( 2 , 7 ) are coupled to the actuating device ( 9 ) or the shaft ( 1 ) via one or more transmission means ( 6 ), in particular one or more gears. 10. Positioning unit according to claim 9, characterized in that the scales ( 2 , 7 ) are designed as discs. 11. Positioning unit according to claim 9 or 10, characterized in
that a scale ( 7 ) for indicating the number of complete revolutions of the shaft ( 1 ) is coupled to the adjusting device ( 9 ) or the shaft ( 1 ) via one or more transmission means ( 6 ), in particular one or more gears, and
that a scale ( 2 ) for indicating the position of the shaft ( 1 ) within a complete revolution of the shaft ( 1 ) relative to the shaft ( 1 ) is fixed in place and substantially concentric with the shaft ( 1 ) and a pointer ( 3 ) can be arranged on the shaft ( 1 ) so as to be fixable substantially at right angles to the longitudinal axis of the shaft ( 1 ). 12. Positioning unit according to claim 11, characterized in that the pointer ( 3 ) can be fixed to the shaft ( 1 ) via fastening means that can be attached to the shaft ( 1 ). 13. Positioning unit according to claim 12, characterized in that the fastening means is a fastening ring ( 15 ) with an inner diameter corresponding to the outer diameter of the shaft ( 1 ), wherein the fastening ring ( 15 ) has at least one projection ( 17 ) pointing essentially in the radial direction of the ring opening, preferably at least two projections ( 17 ) pointing essentially in the radial direction of the ring opening, which engage(s) in recesses ( 14 ) provided in the shaft ( 1 ). 14. Positioning unit according to claim 13, characterized in that the fastening ring ( 15 ) is designed like an annular disk and has at least one opening ( 16 ), preferably at least two openings ( 16 ), in the annular disk area. 15. Positioning unit according to claim 13, characterized in that the pointer ( 3 ) is designed like an annular disk and has at least one opening ( 16 ), preferably at least two openings ( 16 ), in the annular disk area. 16. Positioning unit according to claim 14 or 15, characterized in that the pointer ( 3 ) and the fastening ring ( 15 ) are glued, soldered, welded, screwed and/or riveted to one another at the openings ( 16 ). 17. Positioning unit according to at least one of claims 9 to 16, characterized in that the scale ( 2 ) for indicating the position of the shaft ( 1 ) within a complete revolution of the shaft ( 1 ) has a scaling with an accuracy of at least 3.6°, preferably of at least 0.36°. 18. Positioning unit according to claim 9, characterized in that the scales ( 2 , 7 ) are designed as number drums.