DE29622645U1 - Turning device for a CNC machine tool - Google Patents

Description

Turning device for a CNC machine tool

The invention relates to a device for machining a stationary workpiece by turning on a CNC machine tool.

Rotating workpieces can be easily machined on a CNC-controlled lathe using turning operations such as longitudinal, face and contour turning, as such CNC lathes always have a cross-slide system, with the help of which a turning tool can be moved in two perpendicular directions, e.g. in the direction of the workpiece rotation axis (Z axis) and in a direction perpendicular to this (X or Y axis).

Turning tasks are much more difficult to complete if the workpiece is stationary (or is held so that it can move but does not rotate) and a rotating turning tool must therefore be used, as is the case with transfer machines and rotary indexing table machines, but also with lathes when the turning axis does not coincide with the rotation axis of the workpiece spindle holding the workpiece and the workpiece must therefore remain stationary, as is the case, for example, if the workpiece is to be provided with an eccentric or inclined hole.

In all these cases of real turning operations (i.e. not just drilling or thread cutting), rotating

rotating turning tools are required which not only require a feed of the workpiece and tool relative to each other in the direction of the tool rotation axis, as is sufficient for drilling and thread cutting, for example, but in which the diameter of the path (so-called flight circle) described by the cutting edge of the rotating turning tool must be variable.

So-called facing and boring heads are known for such turning operations, but they have considerable disadvantages; there are also considerable limitations with regard to the turning operations that can be carried out with these facing and boring heads.

For example, a pure so-called facing head is known, which is carried by a rotary-driven machining spindle and has at least one so-called cross slide, which acts as a tool carrier and can be moved perpendicular to the axis of the machining spindle via a gear, whereby the gear is supported by a so-called torque support. To adjust the cross slide, the gear must be engaged and disengaged, whereby the engagement is effected by means of a mechanical or pneumatic impulse, while the release of the coupling is carried out by a fixed stop. Such a facing head is not flexible in terms of machining options and does not allow longitudinal turning or even real contour turning.

A known boring head has a tension core for the radial positioning of a tool carrier, which is moved axially by an actuator via a thrust bearing, and the axial movement is then transmitted via a wedge gear to a

Because of the long transmission distances and the many joints between the actuator and the tool carrier, such a boring head does not work very precisely and has a considerable hysteresis and a considerable amount of play. In addition, its construction is quite complex.

Another known boring head has a battery-powered servomotor arranged in a machining spindle designed as a hollow shaft, which can change the position of the cross slide and thus the cutting circle diameter of the tool cutting edge in small steps; the adjustment device comprising the servomotor is controlled by infrared signals. One of the main disadvantages of this known boring head is that the cutting circle diameter cannot be changed during turning, i.e. when the tool cutting edge is loaded by the machining process.

Starting from a turning device intended for a CNC machine tool with a housing, a main shaft that is rotatably mounted about a drive shaft axis and can be driven in rotation by a main drive motor, a tool holder for a turning tool with a cutting edge that can be driven in rotation about the drive shaft axis by the latter, and an adjusting device with a second motor for changing the radial distance of the tool cutting edge from the drive shaft axis, i.e. for changing the cutting circle diameter, the invention was based on the task of designing such a turning device in such a way that it enables an extremely precise, controlled change in the cutting circle diameter of the tool cutting edge, even under cutting load, with the simplest possible construction.

el. i.e. during turning. A turning device of this kind that solves this task also allows a path-controlled movement of the tool cutting edge superimposed on the rotary movement, as is known from a turning tool for machining rotating workpieces, which is carried by a cross-slide system, the slides of which each have an NC axis.

According to the invention, this object can be achieved in that the adjusting device has an auxiliary shaft which is also mounted so as to be rotatable about the drive shaft axis and is in rotary connection with the second motor, and in that the two shafts can be rotated relative to one another, so that the radial distance of the tool cutting edge from the drive shaft axis can be changed by a corresponding control of at least one of the two motors.

In comparison to the known boring head described above with a battery-powered servomotor arranged in a machining spindle designed as a hollow shaft, the turning device according to the invention has the following advantages in particular: The motor that changes the cutting circle diameter does not have to be housed in a hollow shaft, so that it neither has to be battery-powered nor is its size and thus its performance limited; the cutting circle diameter can therefore also be changed during turning, which is what enables a real path-controlled movement of the tool cutting edge and thus real contour turning. Furthermore, this drive does not have to be controlled wirelessly, and the change in the cutting circle diameter does not have to take place step by step.

In principle, a turning device according to the invention allows the drive to change the cutting circle diameter of the tool cutting edge to be put into operation only when such a change is to be carried out; however, preferred embodiments are those in which the adjustment device is designed in such a way that, when the auxiliary shaft runs synchronously with the main shaft, the path of the tool cutting edge is a circle concentric with the drive shaft axis, while different speeds of the two shafts lead to a change in the cutting circle diameter. With appropriate design of the construction, the advantage can even be achieved that the power of the two motors can be added together to increase cutting performance.

A precise path-controlled movement of the tool cutting edge can be achieved most easily if a rotary angle position sensor is provided for the main shaft and for the auxiliary shaft (which can also be integrated into the associated motor) in order to be able to directly and precisely measure the angle of rotation by which one shaft is rotated relative to the other.

Furthermore, in order to achieve the highest possible precision in controlling the flight circle diameter, it is recommended to use a servo motor for at least one of the two motors and in particular for the motor driving the auxiliary shaft.

As can be seen from the above, particularly advantageous embodiments of the turning device according to the invention are characterized by an electronic gear function implemented by a CNC control for superimposing the speeds of the main and auxiliary shafts for the purpose of turning the

one shaft relative to the other; such electronic gear functions of CNC controls for machine tools are well known and therefore do not require any further explanation.

Advantageous further developments of the invention result from the appended claims and/or from the following description as well as the appended drawing of particularly advantageous embodiments of the turning device according to the invention; in the drawing:

Fig. 1 shows a longitudinal section through a first embodiment including a machine carriage carrying the turning device;

Fig. 2 a first embodiment of a transmission

for changing the cutting circle diameter, as used in the turning device shown in Fig. 1, viewed in the direction of the drive shaft axis;

Fig. 3 is a representation corresponding to Fig. 2

an alternative embodiment of such a transmission;

Fig. 4, 4a, 5,

5a, 6 and 6a Diagrams explaining the movement of the

tool cutting edge;

Fig. 7 is a representation corresponding to Fig. 1

a second embodiment of the turning device according to the invention;

Fig. 8 shows the essential parts of a third embodiment of the turning device according to the invention in longitudinal section;

Fig. 9 is a schematic representation of the path of the

Tool cutting edge in the turning device according to Fig. 8 during the change of the cutting circle diameter;

Fig. 10 the essential parts of a fourth embodiment of the turning device according to the invention in longitudinal section, and

Fig. 11 is a front view of this fourth embodiment

form, as shown in Fig. 10, seen from the right.

Fig. 1 shows a lower or guide part 12 of a slide system, for example, mounted on a machine bed 10 of a machine tool (as can be seen from the explanations given at the beginning, the guide part 12 could also be the lower slide of a cross slide system). A slide 14 is mounted on this guide part 12 so that it can be moved back and forth in the direction of the double arrow "Z" (e.g. Z axis) and is moved by means of a so-called NC axis under the influence of a CNC control of a machine tool.

controlled displacement. The NC axis includes a servo motor 16 attached to the guide part 12 with an integrated position measuring device for transmitting the position of the slide 14 to the machine control, a threaded spindle 18 extending in the Z direction and drivable by the servo motor 16 in both directions of rotation, and a nut 20 running on this and firmly connected to the slide 14, which together with the threaded spindle 18 forms a known ball screw drive.

The carriage 14 is part of a two-part housing 22 of a turning device 24; this accommodates a main shaft 28 in a longitudinal bore 26, which is mounted in the housing 22 by means of bearings 30 so as to be axially immovable but rotatable about a drive shaft axis 32.

At its right-hand end as shown in Fig. 1 and located outside the housing 22, the main shaft 28 carries a facing head with a slide base 36 firmly connected to the main shaft 28 and a cross slide 38, which is guided in a known manner and therefore not shown on the slide base 36 so as to be displaceable perpendicular to the drive shaft axis 32 and holds a turning tool 40, the cutting edge or cutting tip of which is effective for cutting has been designated 42. The left-hand end of the main shaft 28 as shown in Fig. 1 and located outside the housing bore 26 is provided with a toothed belt pulley 44.

According to the invention, the main shaft 28 is designed as a hollow shaft and comprises an auxiliary shaft 46 concentric with it, which is mounted in the main shaft 28 with the aid of a bearing 48 so that it can rotate but cannot move axially, so that it can also rotate around the drive shaft axis 32.

dimension Fig. 1 At the right end of the auxiliary shaft 46, a cam disk 50 arranged in the facing head 34 is attached, and two scanning rollers 52 and 54 are arranged on the facing slide 38, which lie within the facing head 34, can rotate freely about axes parallel to the drive shaft axis 32 and, according to the invention, accommodate the cam disk 50 between them without play in the guide direction of the facing slide 38. Instead of two scanning rollers, however, only a single scanning roller could be used, which is pressed against the cam disk 50 by a spring.

A main drive motor 58 is mounted on the housing 22, on whose shaft 60 a toothed belt pulley 62 is attached, over which and the toothed belt pulley 44 a toothed belt 64 runs. The main drive motor 58 could also drive the main shaft 28 via a simple gear transmission, or this motor could be a so-called hollow shaft motor, the rotor of which would then best be arranged between the two bearings 30 and connected to the main shaft 28.

The left end of the auxiliary shaft 46 according to Fig. 1 is connected to the shaft 66 of a servo motor 68, which is also mounted on the housing 22, in such a way that the motor shaft 66 runs coaxially to the drive shaft axis 32.

Both the main drive motor 58 and the servo motor 68 have an integrated rotation angle position measuring device (not shown) in order to be able to continuously transmit the rotation angle positions of the main shaft 28 and the auxiliary shaft 46 to the CNC control of the machine tool. In order to meet particularly high accuracy requirements, the current rotation angle position of the main shaft 28 can alternatively be detected by a probe head 70 attached to the housing 22.

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which scans a rotary encoder 72 attached to the main shaft 28, so that accuracy errors caused by the toothed belt drive 44, 62, 64 are excluded.

The CNC control of the machine tool and its connections to the two motors 58 and 68 as well as to the angle of rotation position measuring devices were not shown, as these are elements of machine tool construction that are familiar to the expert.

As can be seen from Fig. 2, the circumference of the cam disk 50 forms two curve sections 50a and 50b, which are mirror images of a plane of symmetry 50c containing the drive shaft axis 32. In the embodiment shown in Fig. 2, the shapes of the curve sections 50a and 50b correspond to involutes with a base circle 50d concentric with the drive shaft axis 32 and a base circle radius r _g . As will become clear from the following, the two curve sections forming the circumference of the cam disk could also correspond to Archimedean spirals. As can be seen from Fig. 2 in conjunction with Fig. 1, the axes 52a and 54a, which are parallel to the drive shaft axis 32 and about which the scanning rollers 52 and 54 rotate, lie in a plane 76 which, according to the invention, is tangent to the base circle 50d and runs parallel to the guide direction of the cross slide 38 and parallel to the direction of movement Z of the slide 14; moreover, the plane 76 is arranged according to the invention with respect to the drive shaft axis 32 and thus with respect to the axis of rotation of the cam disk 50 in such a way that the tangents placed at the scanning points on the circumference of the cam disk 50 always run parallel to one another and perpendicular to the plane 76, with the scanning points being those points.

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where the scanning rollers 52 and 54 touch the circumference of the cam disk 50.

The advantage of a cam control for the cross slide 38 or for the radial distance of the tool cutting edge from the drive shaft axis 32 is primarily that a rotary movement of the main shaft 28 and auxiliary shaft 46 relative to each other is converted directly into a linear movement of the turning tool, i.e. into a change in the radial distance of the tool cutting edge from the drive shaft axis 32.

If the scanned curves have an involute shape, there is also a linear relationship between the angle of rotation and the adjustment path of the tool, as well as the advantage that the scanning points are always in the plane 76, i.e. they are opposite each other in such a way that the direction of the forces between the scanning rollers and the cam disk is always the same as the direction of movement of the tool or the cross slide 38, thereby avoiding force components directed transversely thereto.

The usable angle of rotation of the cam disk 50 is slightly smaller than 180° due to the transitions of the cam sections 50a and 50b into one another. However, the cam disk 50 is still suitable for smaller tool adjustment paths, such as those required for boring tools. This is illustrated in Fig. 1, in which a workpiece 78 is shown in longitudinal section, the bore 80 of which, coaxial with the drive shaft axis 32, has been expanded to form an inner cone 82 using the turning tool 40.

The alternative curve shape shown in Fig. 3 has the advantage over the curve shape shown in Fig. 2 that the angle of rotation of the curve can basically be as large as desired,

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This means that the same applies to the adjustment path of the tool or the cross slide 38. In Fig. 3, the same reference numerals were used as in Fig. 2, but with the addition of a prime insofar as the elements shown in Fig. 3 are designed and/or arranged differently compared to the embodiment according to Fig. 2.

In the embodiment shown in Fig. 3, the cam disk 50 according to Fig. 2 is replaced by a web-shaped cam element, which will be referred to below as the cam web 50". The two long sides of the cam web 50' form two cam sections 50a' and 50b', the shape of which again corresponds to involutes and which are scanned with the help of two scanning rollers 52' and 54' in such a way that the two scanning rollers accommodate the cam web 50' between them without play and the two scanning points lie on a plane 76' corresponding to the plane 76 of the embodiment according to Fig. 2, which is tangent to the base circle 50d' for the two involutes and runs perpendicular to the two tangents which are placed at the scanning points on the cam sections 50a' and 50b'. The rotation of the cam web 50' again takes place around the drive shaft axis 32, which in this embodiment also through the center of the base circle 5Od ¹ of the two involute curve sections 50a' and 50b'.

Of course, the advantages of the involute shape described above also apply to the embodiment according to Fig. 3, but Fig. 3 makes it particularly clear that the shape of the scanned curve or curves could also correspond to Archimedean spirals.

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For the sake of completeness, it should be mentioned that the body 51' provided with the cam web 50' takes the place of the cam disk 50 shown in Fig. 1.

The diagrams shown in Figures 4, 4a, 5, 5a, 6 and 6a are intended to illustrate the movement sequence of the adjustment device according to the invention.

Fig. 4 shows the course of the angle of rotation Cp ₁ of the servo motor 68 or the auxiliary shaft 46 or the cam disk 50 over time (t) - with the main drive motor and thus the main shaft 28 at a standstill - for a forward and reverse movement of the cross slide 38 or for a radial extension and retraction of the turning tool 82.

In Fig. 4a, the corresponding rotational angular velocity O ₁ of the cam disk 50 is shown as a function of time.

Fig. 5 shows the course of the angle of rotation q> ₂ of the main shaft 28 over time (t) when the main shaft rotates uniformly, ie with a constant angular velocity, as shown in Fig. 5a, in which the angular velocity (S) ₂ of the main shaft 28 is shown over time (t).

During turning, the main shaft 28 and auxiliary shaft 46 rotate at the same and constant speed as long as the diameter of the cutting circle of the tool cutting edge is not changed; in this case, Figures 5 and 5a also apply to the auxiliary shaft 46 and the cam disk 50, respectively, and the two shafts 28 and 46 are therefore not rotated relative to one another. If, during turning, i.e.

As long as the main spindle 28 and the auxiliary shaft 46 are driven, the diameter of the flight circle of the tool cutting edge is changed, the initially synchronously driven shafts 28 and 46 are rotated relative to one another, whereby the temporal progression of the angle of this relative rotation for a forward and reverse movement of the cross slide 38 again corresponds to Fig. 4. Fig. 6 now shows the temporal progression of the angle of rotation of one of the two shafts, assuming that the other shaft rotates at a constant speed according to Figs. 5 and 5a; in the embodiment shown in Fig. 1, Fig. 6 is intended to show the temporal progression of the angle of rotation of the servo motor 68 and thus of the auxiliary shaft 46 and the cam disk 50, and Fig. 6a shows the temporal progression of the corresponding angular velocity.

It follows from Figures 6 and 6a that, according to the invention, the "adjustment movement", i.e. the rotation of the cam disk 50 used to change the diameter of the cutting circle of the tool, is always superimposed on the rotary movement of the main shaft 28.

In order to produce the contour shown in Fig. 1 on a workpiece, for example, the change in the diameter of the cutting circle of the tool cutting edge is coordinated with a movement of the entire turning device (alternatively with a movement of the workpiece 78 in the Z direction), with the help of the CNC control of the machine tool, in the case shown in Fig. 1 with a longitudinal movement of the slide 14 in the Z direction. However, the invention is not limited to this, because with the help of a turning device according to the invention, any contours can be produced if the adjustment movement of the turning tool in the radial direction.

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ation is coordinated with movements of the entire turning device (or the workpiece) corresponding to the contours to be created, for example with movements in the direction of the Z-axis, the X-axis and/or the Y-axis of the machine tool.

The CNC controls for machine tools available on the market today enable these functions, i.e. the function of a so-called electronic gear and the coordination (interpolation) with the movements of one or more NC axes of machine slides.

The second embodiment of the turning device according to the invention shown in Fig. 7 will be described below only insofar as it differs from the embodiment according to Fig. 1; insofar as the embodiment according to Fig. 7 has the same elements as the embodiment according to Fig. 1, the same reference numerals were used for these elements in Fig. 7 as in Fig. 1.

In the embodiment according to Fig. 7, an auxiliary shaft 146 coaxial with the drive shaft axis 32 is mounted by means of bearings 148 so that it can rotate but cannot move axially in a main shaft 128 which is also coaxial with the drive shaft axis 32 and is designed as a hollow shaft. The right-hand area of the auxiliary shaft 146 according to Fig. 7 is designed as a threaded spindle 146a, preferably as a ball screw spindle, which interacts with a slider 150 which forms a ball screw nut for the threaded spindle 146a and is mounted in the main shaft 128 so that it can move in the direction of the drive shaft axis 32 but cannot rotate relative to the main shaft 128. For this purpose, the slider 150 has a web on its outer circumference which is parallel to the drive shaft axis 32.

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(usually called a spring) which engages in a groove (not shown) on the inner circumference of the main shaft 128, which runs parallel to the drive shaft axis 32, and is guided in this groove so that it can be moved transversely to the longitudinal direction of the groove but without play, so that it is guaranteed that the slide 150 cannot rotate relative to the main shaft 128. If the main shaft 128 and the auxiliary shaft 146 rotate synchronously, i.e. at the same speed, the slide 150 rotates with the main shaft 128 and the threaded spindle 146a without being moved in the direction of the drive shaft axis 32.

The right end of the main shaft 128 according to Fig. 7 in turn carries a facing head 134 with a slide base 136, which is firmly connected to the main shaft 128 and has guides (not shown in detail) that run perpendicularly and radially to the drive shaft axis 32 and are aligned with one another for each of the two cross slides 138a and 138b, which are diametrically opposite one another with respect to the drive shaft axis 32 and can therefore be moved in opposite directions by means to be described (of course, the guides mentioned must hold the two cross slides in the direction of the drive shaft axis 32 on the slide base 136 without play). Each of the two cross slides 138a, 138b carries a turning tool 140a or 140b.

The two cross slides 138a and 138b as well as the slide 150 are provided with means which form a wedge gear 152a or 152b for each of the two cross slides in order to convert a displacement of the slide 150 in the direction of the drive shaft axis 32 into opposing radial movements of the two cross slides. Such wedge gears are known, so that they do not have to be shown and described in detail in a drawing. However, Fig. 7 shows

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that the right-hand area of the slide 150 according to Fig. 7 is wedge-shaped, so that each of the wedge gears 152a, 152b can be designed as follows, for example: a web with a T-shaped cross section is attached to the relevant cross slide, a guide with a T-shaped cross section groove on the slide 150, into which the said web engages without play and in which this web is guided so as to be displaceable in its longitudinal direction or the longitudinal direction of the groove. The web and groove are inclined relative to the drive shaft axis 32 in the manner shown in Fig. 7, so that a displacement of the slide 150 according to Fig. 7 to the right causes the two cross slides 138a, 138b to move apart synchronously, and a displacement of the slide 150 according to Fig. 7 to the left causes the two cross slides to move closer together synchronously, whereby the two wedge gears 152a, 152b are designed and arranged in such a way that in every position of the slide 150 or the two cross slides, the cutting edges of the two turning tools 140a, 140b are equidistant relative to the drive shaft axis 32.

With the aid of the turning device shown in Fig. 7 and a coordinated displacement of the slide 14 in the Z direction, an external cone 182 coaxial with the drive shaft axis 32 can be produced on a stationary workpiece 178, for which, in addition to the displacement of the slide 14 in the Z direction, only a rotation of the auxiliary shaft 146 and the main shaft 128 relative to one another is required in order to displace the slide 150, while the rotation of circular-cylindrical surfaces coaxial with the drive shaft axis 32 on a workpiece requires that the slide 14 is displaced in the Z direction, while the main shaft 128 and the auxiliary shaft 146 are driven synchronously, i.e. at the same speed.

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The second embodiment shown in Fig. 7 brings with it the following advantages in particular: If there are several cross slides that can move in opposite directions with respect to the drive shaft axis 32, there is no imbalance caused by the rotating parts - provided they have been balanced beforehand. In addition, the cutting power required for turning is distributed over several tool cutting edges, so that with the embodiment shown in Fig. 7, work can be carried out with twice the feed in the Z direction than when using just a single turning tool. A slim workpiece also does not experience any bending during turning, but only a torque load resulting from the cutting forces if work is carried out simultaneously with several tools arranged at an equidistant angle of rotation.

In the embodiment shown in Fig. 7, the servo motor 68 must generate a torque with which the centrifugal forces acting on the cross slide and turning tools are overcome, i.e. even without an adjustment movement of the turning tools in the radial direction, a drive power of this servo motor is required which is greater than the drive power required to overcome the bearing friction; this additional drive power is added to the power generated by the main drive motor 58 to increase cutting performance.

A third embodiment of the turning device according to the invention is to be explained with reference to Figures 8 and 9, which differs fundamentally from the first two embodiments in a certain way, but is only shown in the drawing to this extent and is described below.

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will be described in more detail than is necessary for understanding this third embodiment.

The longitudinal section shown in Fig. 8 through a front area (relative to the workpiece to be machined) of this turning device shows a shaft 202 coaxial with a drive shaft axis 200 (which preferably forms the main shaft in the sense of the claims and is therefore referred to as such in the following) and a shaft 204 designed as a hollow shaft and also coaxial with the drive shaft axis 200 (which preferably forms the auxiliary shaft in the sense of the claims and is therefore referred to as such in the following), in which the shaft 202 is rotatably mounted by means of a bearing 206. With the help of bearings 208 and 210, a tool spindle 212 is also rotatably mounted in the auxiliary shaft 204, but in such a way that a tool spindle axis 214, around which the tool spindle 212 can rotate, runs parallel to the drive shaft axis 200, but is offset from it by an eccentricity "e". The tool spindle 212 carries a turning tool 216 with a cutting edge 218, the cutting-effective tip of which is designated 220. So that the tool spindle 212 can be driven by the main shaft 202 despite the eccentricity e and is rigidly connected to it in terms of angle of rotation, the right end of the main shaft 202 as shown in Fig. 8 was connected to the left end of the tool spindle 212 as shown in Fig. 8 via a compensating coupling 222; Such compensating couplings are known in the prior art, and Fig. 8 shows a preferred embodiment in the form of a likewise known metal bellows coupling.

Regarding the drives for the main shaft 202 and the auxiliary shaft 204 and regarding the control of these drives,

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For the drive, reference can be made to Fig. 1 and the explanations given therefor, i.e. the main shaft 202 is driven by a motor corresponding to the main drive motor 58 shown in Fig. 1, and the auxiliary shaft 204 is driven by a servo motor corresponding to the servo motor 68 shown in Fig. 1; however, the shaft 204 is preferably driven uniformly (due to its greater mass) and a servo motor is consequently used to drive the shaft 202.

In the third embodiment shown in Figures 8 and 9 (and the same applies to the fourth embodiment, which is still to be described and shown in Figures 10 and 11), a rotating tool carrier, namely the tool spindle 212 in the case of the third embodiment, takes the place of a cross slide as a tool carrier. The embodiment according to Figures 8 and 9 has the advantage, among other things , that no gears are required to convert a rotary or linear movement into a movement which corresponds to the change in the diameter of the cutting circle of the tool cutting edge. In contrast, in the third embodiment according to Figures 8 and 9, there is no strictly linear relationship between the angle of rotation by which the main shaft and auxiliary shaft are rotated relative to one another and the change in the diameter of the cutting circle of the tool cutting edge; however, this is also not necessary if contours are not produced by turning. However, if the latter is required, the linear relationship not provided by the mechanics can be brought about by a corresponding program which is processed by the CNC control of the machine tool,

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If the turning device according to Figures 8 and 9 is to be used to produce a circular cylindrical surface coaxial with the drive shaft axis 200 on a stationary workpiece, the main shaft 202 and the auxiliary shaft 204 are driven synchronously, i.e. at identical speeds, and at the same time the turning device is advanced in the direction of the drive shaft axis 200, i.e. in the Z direction. To change the diameter of the flight circle of the tip 220 of the turning tool cutting edge, the main shaft 202 and the auxiliary shaft 204 are rotated relative to one another in order to change the radial distance of the cutting edge tip 220 from the drive shaft axis 200.

Fig. 9 shows, on the one hand, a flight circle 230 through which the cutting tip 220 runs when and as long as the main shaft 202 and the auxiliary shaft 204 are driven synchronously, i.e. at identical speeds, and, on the other hand, a path 232 through which the cutting tip 220 runs when the auxiliary shaft 204 is stationary and the main shaft 202 is rotated in order to change the radial distance of the cutting tip 220 from the drive shaft axis 200. From this it is clear that when the main shaft 202 and the auxiliary shaft 204 are rotating, the diameter of the flight circle of the cutting tip 220 can be changed, even continuously, when the two shafts 202 and 204 are rotated relative to one another.

Since the adjustment paths of such boring or fine turning tools, for which the turning tool 216 of the turning device according to Figures 8 and 9 is representative, are only relatively small and, for example, only have to be 0.1 mm, the eccentricity e and the angle by which the two shafts 202 and 204 are rotated relative to each other can be

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must also be quite small; in this case, there is a practically linear relationship between the mentioned angle of rotation and the adjustment path of the tool cutting edge. The resolution is also very high, i.e. by rotating the two shafts 202 and 204 relative to each other, the desired adjustment paths can be set very precisely. It can also be mathematically derived that the size of the adjustment path per degree of rotation of the two shafts 202 and 204 relative to each other is practically (although not mathematically strictly) independent of the diameter of the tool cutting edge's flight circle.

A further advantage of the embodiment of the turning device according to the invention shown in Figures 8 and 9 is that this embodiment represents an extremely space-saving and stable construction and that completely unbalance-free operation is possible regardless of the adjustment of the turning tool - this only requires that the center of gravity of the tool spindle 212 including the turning tool 216 lies in the tool spindle axis 214 representing the swivel axis and that the entire assembly, consisting of the main shaft 202, compensating coupling 222, tool spindle 212, turning tool 216 and auxiliary shaft 204 including their bearings, has been balanced.

In principle, the compensating coupling 222 could be replaced by a gear transmission; however, a compensating coupling has the advantage that it is simpler and has a smaller ex-

The fourth embodiment shown in Figures 10 and 11 is relatively close to the first embodiment according to Figure 1 and has therefore only been shown in the drawings

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and will be described below only to the extent that this fourth embodiment differs from the first embodiment and as is necessary for understanding the fourth embodiment.

The fourth embodiment according to Figures 10 and 11 has a main shaft 428 that is coaxial with a drive shaft axis 432 and designed as a hollow shaft, in which an auxiliary shaft 446 that is also coaxial with the drive shaft axis 432 is rotatably and axially immovably mounted by means of a bearing 450. The drive of the main shaft 428 can correspond to the drive of the main shaft 28 shown in Fig. 1, the drive of the auxiliary shaft 446 can correspond to the drive of the auxiliary shaft 46 shown in Fig. 1. A bell-shaped housing part 452 of a tool head 434 is firmly connected to the right end of the main shaft 428 according to Fig. 10, and another housing part 454 of the tool head is attached to the housing part 452 in a removable manner. A pivot shaft 458a or 458b is arranged in a rotatable and axially immovable manner in two bores 456a and 456b of the housing part 454, which are parallel to the drive shaft axis 432 and equidistant from one another and diametrically opposite one another with respect to this axis; the right-hand ends of these pivot shafts as shown in Fig. 10 are each firmly connected to a pivot lever 460a or 460b, while the left-hand ends are connected to a pivot lever-like toothed segment 462a or 462b. The pivot levers 460a and 460b serve as tool carriers, as was made clear by the tool cutting edges 440a and 440b attached to these pivot levers.

The housing part 452 forms a first ring gear 464 of a planetary gear provided with an inner, circular toothing 464a, a second ring gear 466 is freely rotatably mounted on the auxiliary shaft 446, and a

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The planetary gear carrier 468 of this planetary gear, which is supported by the planetary gear carrier 468, is connected to the auxiliary shaft 446 in a rotationally fixed manner (of the connecting means, Fig. 10 only shows a web (a so-called spring) 471 on the auxiliary shaft 446); the internal, circular toothing of the second ring gear 466 was designated 466a. Finally, the planetary gear comprises several planet gears 470, which are freely rotatably mounted in the planetary gear carrier 468 and mesh with the toothing 464a and 466a of the two ring gears 464 and 466. A gear 466b is also formed on the second ring gear 466, in the toothing of which the toothing of the two tooth segments 462a and 462b engage.

According to the invention, the toothings 464a and 466a differ in their number of teeth, but only slightly, e.g. by two teeth. Each of the planetary gears 470 could now be provided with two toothings, one of which corresponds to the toothing 464a and the other to the toothing 466a, but the person skilled in the art will know that instead the toothings 464a and 466a can also be corrected so that they can converge with a single toothing of each of the planetary gears.

If a circular cylindrical surface coaxial with the drive shaft axis 432 is to be turned using the turning device according to Figures 10 and 11, the main shaft 428 and the auxiliary shaft 446 are driven synchronously, i.e. at identical speeds, which results in the tips of the two tool cutting edges 440a and 440b having constant and identical radial distances from the drive shaft axis 432. To change the diameter of the flight circle that the tips of the two tool cutting edges describe and which is always identical for both cutting edges, the two

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Shafts 428 and 446 are again rotated relative to one another, which, thanks to the planetary gear, results in the two pivot levers 460a and 460b being pivoted synchronously and in the same direction, i.e. both clockwise or both counterclockwise, in the view according to Fig. 11; the tips of the tool cutting edges 440a and 440b thereby traverse circular arcs around the axes of the pivot shafts 458a and 458b, whereby the radial distance of the tips of the tool cutting edges from the drive shaft axis 432 is synchronously increased or reduced.

The fourth embodiment of the turning device according to the invention, as shown in Figures 10 and 11, has the advantage, among other things, that only small centrifugal forces are generated on the pivot levers 460a, 460b; in addition, the adjustment device of this embodiment has a high resolution and allows large machining forces.

As is readily apparent, the actual planetary gear could also be arranged in the area of the left ends of the shafts 428 and 446 as shown in Fig. 10, so that only the toothed segments 462a, 462b and the gear 466b remain in the tool head 434. Another reduction gear could also take the place of the planetary gear.

It is obvious that if internal turning or external turning has been shown for the various embodiments, the tools and tool holders can also be designed so that external turning or internal turning is also possible with the respective embodiment.

Claims (1)

- 26 - Expectations 1. Turning device for a CNC machine tool, with a housing, a main shaft which is rotatably mounted about a drive shaft axis and can be driven in rotation by a main drive motor, a tool carrier for a turning tool having a cutting edge which can be driven in rotation by the latter about the drive shaft axis, and an adjusting device having a second motor for changing the radial distance of the tool cutting edge from the drive shaft axis, characterized in that the adjusting device (68, 46, 50, 52, 54, 38; 50', 52·, 54'; 146a, 150, 152a, 152b, 138a, 138b; 204, 212; 446, 464, 466, 468, 470, 466b, 462a, 462b, 460a, 460b) has an auxiliary shaft (46; 146; 204; 464) which is also rotatably mounted about the drive shaft axis (32; 200; 432) and is in rotary connection with the second motor (68 or 58), and that the two shafts (28, 46; 128, 146; 202, 204; 428, 446) are rotatable relative to one another, so that the radial distance of the tool cutting edge (42; 218; 440a, 440b) from the drive shaft axis can be changed by a corresponding control of at least one of the two motors (58, 68). 2. Device according to claim 1, characterized in that the adjusting device (68, 46, 50, 52, 54, 38; 50', 52', 54'; 146a, 150, 152a, 152b, 138a, 138b; 204, 212; 446, 464, 466, 468, 470, 466b, 462a, 462b, 460a, 460b) is designed such that when the auxiliary shaft (46; - 27 - 146; 204; 446) the path of the tool cutting edge (42; 218; 440a, 440b) is a circle concentric with the drive shaft axis (32; 200; 432). 3. Device according to claim 1 or 2, characterized in that a rotary angle position sensor (70, 72) is provided for the main shaft (28; 128; 202; 428) and for the auxiliary shaft (46; 146; 204; 446), in particular integrated into the associated motor (58 or 68). 4. Device according to one or more of the preceding claims, characterized in that at least one of the two motors (58, 68) and in particular the second motor (68 or 58) is a servo motor. 5. Device according to one or more of the preceding claims, characterized in that one of the shafts is a hollow shaft (28; 128; 204; 428) surrounding the other shaft (46; 146; 202; 446). 6. Device according to claim 5, characterized in that one shaft (46; 146; 202; 446) is rotatably mounted in the other (28; 128; 204; 428). 7. Device according to claim 5 or 6, characterized in that the main shaft (28; 128; 428) is designed as a hollow shaft. 8. Device according to one or more of the preceding claims, characterized by an electronic gear function implemented by a CNC control for superimposing the speeds of the main and auxiliary shaft in order to rotate one shaft relative to the other. 9. Device according to one or more of the preceding claims, characterized in that the second motor (68 or 58) is connected to the housing (22). 10. Device according to one or more of the preceding claims, characterized in that the adjusting device has at least two adjusting elements (50, 52, 54; 50', 52', 54') which are movable relative to one another in a plane running perpendicular to the drive shaft axis (32) and of which a first is in rotary connection with the auxiliary shaft (46) and a second with the main shaft (28), and in that one adjusting element is a scanning element (52, 54; 52', 54') for a feed curve (50a, 50b; 50a', 50b') formed by the other adjusting element (50; 50') and lying in this plane. 11. Device according to claim 10, characterized by two scanning elements (52, 54; 52', 54 ¹ ) which accommodate the feed curve (50; 50') between them without play. 12. Device according to claim 10 or 11, characterized in that the feed curve (50; 50') is attached to the auxiliary shaft (46), that the main shaft (28) carries a slide guide extending perpendicularly to the drive shaft axis (32) for a tool carrier slide (38) and the latter carries the scanning element (52, 54; 52', 54'). - 29 - 13. Device according to claim 11 or 12, characterized in that - viewed in the direction of the drive shaft axis (32) - the feed curve (50) is approximately heart-shaped and lies between two scanning rollers (52, 54) which are arranged in such a way that in the two scanning points the tangents to the feed curve (50) always run parallel to one another. 14. Device according to claim 11 or 12, characterized in that the feed curve is formed by a web (50 ¹ ) of constant width, on each of the two sides of which a scanning roller (52', 54') is arranged such that the distance between the two scanning points is equal to the web width, so that in the two scanning points the tangents to the feed curve always run parallel to one another. 15. Device according to one or more of claims 10 to 14, characterized in that the shape of the feed curve corresponds to Archimedean spirals. 16. Device according to one or more of claims 10 to 14, characterized in that the shape of the feed curve (50; 50') corresponds to involutes. 17. Device according to one or more of claims 1 to 9, characterized in that the tool carrier (134) has tool carrier slides (138a, 138b) that are diametrically opposed to one another with respect to the drive shaft axis (32), that the main shaft (128) carries a slide guide for each tool carrier slide that extends perpendicularly to the drive shaft axis (32) and that the adjusting device has a slide guide that extends in the direction of the drive shaft axis (32). - 30 - drive shaft axis (32) and actuated by a speed difference between the main and auxiliary shaft (128 or 146) and a reversing gear (152a, 152b) actuated by the latter for the counter-rotating and synchronous movement of the two tool carrier slides. 18. Device according to claim 17, characterized in that the deflection gear is a wedge gear (152a, 152b). 19. Device according to claim 18, characterized in that the wedge gear (152a, 152b) has a wedge element (150) that can be pushed back and forth in the direction of the drive shaft axis (32) by the screw drive (146a, 150) and that the latter and the tool carrier chutes (138a, 138b) are provided with interlocking guide elements that run obliquely to the drive shaft axis. 2.0. Device according to one or more of claims 1 to 9, characterized in that a tool spindle (212) is arranged in a hollow shaft (204) coaxial with the drive shaft axis (200) parallel to the axis, but eccentrically rotatable with respect to the drive shaft axis, so that by a relative rotation of the hollow shaft (204) and the tool spindle (212), the radial distance of the tool cutting edge (218) of a tool (216) carried by the tool spindle from the drive shaft axis (200) can be changed, and that the hollow shaft (204) can be driven by the second motor (68 or 58) and the tool spindle (212) can be rotated via a control (e) - 31 - bridging coupling device (222) is in rotary connection with the main shaft (202). 21. Device according to claim 20 ₇ , characterized in that the coupling device is designed as a compensating coupling (222). 22. Device according to one or more of claims 1 to 9, characterized in that at least one tool holder (460a, 460b) is mounted on the tool carrier (434) so as to be pivotable about an axis parallel to the drive shaft axis (432) and that an actuating gear (468, 470, 464a, 466a, 46.6, 466b, 462a, 462b) is provided for pivoting the tool holder between the latter and the auxiliary shaft (446). 23. Device according to claim 22, characterized in that the actuating gear (468, 470, 464a, 466a, 466, 466b, 462a, 462b) is a gear transmission. 24. Device according to claim 23, characterized in that the gear transmission (468, 470, 464a, 466a, 466, 466b, 462a, 462b) is a planetary gear transmission with a planetary gear carrier (468), at least one planetary gear (470) and two ring gears (464, 466) meshing with the latter, that the planetary gear carrier and the one, first ring gear (464) can be driven by the main shaft (428) or the auxiliary shaft (446), that the tool holder (460a, ~460b) can be pivoted by the second ring gear (466) and that the toothings (464a, 466a) of the two ring gears (464, 466) differ by one tooth or a few teeth. - 32 - 25. Device according to one or more of claims 22 to 24, characterized in that several tool holders (460a, 460b) are provided, with their pivot axes (458a, 458b) arranged equidistantly in terms of angle of rotation. 26. Device according to one or more of the preceding claims, characterized in that the housing (22) is connected to at least one machine carriage (14) that can be displaced in the direction of the drive shaft axis (32). 27. Device according to claim 26, characterized in that the machine slide (14) is assigned at least one NC axis for the controlled displacement of the machine slide in the direction of the drive shaft axis (32). 28. Device according to claim 26 or 27, characterized by a coordination of the movement of the machine carriage (14) with the function of the adjustment device (68, 46, 50, 52, 54, 38; 50', 52', 54'; 146a, 150, 152a, 152b, 138a, 138b; 204, 212; 446, 464, 466, 468, 470, 466b, 462a, 462b, 460a, 460b) realized by a CNC control.