WO2013037562A1 - Shifting unit with spindle drive for a machine tool gearbox - Google Patents

Abstract

The invention relates to a shifting unit for a machine tool gearbox (23), which has a sliding element (28), which is displaceable in an envisaged shifting direction for shifting the machine tool gearbox (23) into various shifting positions, wherein the shifting unit (1) comprises an electric motor (2) with a shaft (3), which rotatably drives a spindle (11) provided with a thread (12), wherein the spindle (11), by means of a rotational motion, translationally moves an entraining element (13) engaged with the thread (12), wherein the entraining element (13) is connected to a shifting element (16; 24) for moving the sliding element (28). The invention further relates to a machine tool gearbox with a shifting unit.

Description

 Switching unit with spindle drive for a machine tool transmission

The present invention relates to a switching unit with spindle drive for a machine tool transmission according to the closer defined in the preamble of claim 1. Art.

From DE 199 17 673 A1 discloses a switching device of a transmission is known in which a sliding sleeve by means of a solenoid in different switching positions is displaced.

The problem underlying the invention is solved by the features of claim 1. Further advantageous embodiments will become apparent from the dependent claims and the drawings.

Accordingly, a switching unit for a machine tool transmission is proposed, which has a sliding element, which is displaceable for switching the power tool gear in various switching positions in a designated displacement direction, wherein the switching unit comprises an electric motor with a shaft which rotatably drives a threaded spindle, wherein the spindle translationally moved by a rotation of a threaded engaging driving element, wherein the driving element is connected to a switching element for displacing the sliding element.

Machine tool transmissions are used in lathes, milling machines but also in other machine tools. They serve in particular to increase the flexibility of the respective machine tool in the processing of different materials and / or different processing operations by varying the speed and / or torque. For this purpose, the machine tool transmission has at least two translations, which can be selected by shifting a sliding element into a switching position assigned to the respective gear ratio. In addition, a further switching position may be provided in which a transmission of torques is interrupted. Such a switching position we also referred to as neutral position. In this case, "displaceable" means that the sliding element can be moved forwards and backwards along a straight line, the orientation of this straight line in space being referred to as the "displacement direction". The term "displacement direction" thus relates to both a displacement of the sliding element in a first direction and a displacement of the sliding element in a second direction opposite thereto.

The sliding element may in particular be a sliding sleeve, which, for example, is displaceable coaxially to a shaft, in particular to a drive shaft and / or an output shaft, of the power tool gear.

The switching unit according to the invention now serves to move such a sliding element of a power tool gearbox between the intended switching positions, so as to switch the machine tool transmission. For this purpose, the switching unit comprises an electric motor which has a shaft which can be set in rotation by electromagnetic forces. The electric motor may in particular be a DC motor. Other electric motor concepts, such as AC motors, three-phase motors, but are also conceivable.

The electric motor is drivingly connected to a threaded spindle, so that it can be driven by the electric motor. In this case, a driving element is provided, which is in engagement with the thread of the spindle. The driving element is designed and mounted so that a rotation of the spindle leads to a translational movement of the driving element. For example, the one-piece or multi-piece carrier element can be designed as a driving plate. The driving element is connected to a switching element, which is designed to move the sliding element by it can transmit the translational movement of the driving element to that of the sliding element. Overall, it is possible to move by a corresponding control of the electric motor of the switching unit, the sliding element between the switching positions, so as to switch the machine tool transmission.

The proposed switching unit can be made very compact overall. It can act on the sliding element along its entire possible movement with a substantially equal force, which is a safe Schal- allows the machine tool transmission. In this case, the transferable to the sliding elements forces can be many times higher than would be possible with comparable construction space and comparable power consumption with a solenoid. With a suitable choice of the total reduction of the switching unit of, for example, at least 15 to 1 so easily switching paths of, for example, at least 15 mm and switching forces of, for example, more than 450 N can be achieved. In addition, the switching unit is self-locking, since the spindle can not be rotated by forces acting on the driving element. Thus, further measures for locking the sliding element in one of the switching positions are unnecessary. Furthermore, the switching unit is easily adaptable to various machine tool transmissions. For this purpose, it is usually sufficient that the switching element is adapted to the shape and the arrangement of the switching element. Optionally, mounting adapter for fixing the switching unit can be provided on a mounting portion of the power tool gearbox.

In an advantageous development, the shaft of the electric motor and the spindle are arranged parallel to one another. As a result, no complex transmission elements for transmitting torques at an angle, such as bevel gears, cardan gears or worm gears, are required between the electric motor and the spindle. In addition, such a high efficiency can be realized by low friction losses. Furthermore, the switching unit can be made so very compact.

Advantageously, the spindle is aligned parallel to the intended displacement direction. As a result, the forces can be transmitted from the spindle to the sliding element in a particularly simple manner. In particular, so the driving element and / or the switching element can be easily performed, which also comes in a space-saving design to good. In addition, this is a high efficiency by low friction losses beneficial.

In an advantageous development, a spur gear is provided between the electric motor and the spindle. Such a spur gear allows a displacement of the shaft of the electric motor and the spindle. As a result, the electric motor and the spindle can be arranged side by side transversely to the axial direction, which a compact design by a reduced axial extent of the switching unit allows. In addition, the spur gear in a simple manner with good efficiency can contribute to the desired overall reduction.

Advantageously, a planetary gear is provided between the electric motor and the spindle. In this way, the desired overall reduction can be achieved in a simple, space-saving manner with good efficiency.

In an advantageous development, a drive shaft of the planetary gear and / or an output shaft of the planetary gear are arranged coaxially with a shaft of the electric motor. In this way, a particularly compact design of the switching unit can be realized with particularly good efficiency.

Advantageously, a slip clutch is provided between the electric motor and the spindle. A slip clutch is an automatic torque-switching safety clutch, which opens at least partially when a maximum torque is exceeded in order to limit the torque output. In this way, ultimately the force on the switching element is limited, which serves in particular to avoid damage to the machine tool transmission.

In an advantageous development, the slip clutch is arranged coaxially with the spindle. In this way, a particularly compact design of the switching unit can be realized with particularly good efficiency.

Advantageously, stationary end stops, in particular axially or radially to the spindle axis for limiting movement of the driving element are provided. In this way, small position tolerances result for the end positions of the driving element. If the end positions correspond to switching positions of the sliding element, then these can be taken in a particularly precise manner, which enables exact shifting. The end positions can be adjusted, for example, by an exchange of the driving element or by adjusting means, such as countered screws on the driving element, which can facilitate an adaptation of the switching unit to different machine tools.

In an advantageous development, at least one limit switch for detecting a receipt of an end position by the driving element is provided. The Limit switches can be used to control the electric motor. In particular, the electric motor can thus be switched off when one of the end positions is reached, without the need for elaborate electronics. If the end positions correspond to switching positions, they can be exactly taken and held in a simple manner.

Advantageously, at least one intermediate layer switch is provided for detecting the receipt of an intermediate layer by the entrainment element. Also, such a liner switch can be used to control the electric motor. In particular, the electric motor can thus be switched off when a defined intermediate layer is reached, without the need for elaborate electronics. Corresponds to the interposition of a switching position, so these can be taken exactly and held in a simple manner.

In an advantageous development, the switching unit has a transmission ventilation. A transmission bleeding is used to avoid overpressure in the gearbox when, for example, the gearbox heats up. However, it should be avoided that through the gear vent lubricants, such as oil or grease escape. If now, as is usual, the switching unit is arranged in an upper region of the power tool gearbox, just this goal can be achieved in a simple manner when the gear vent is formed on the switching unit, since lubricants tend to collect in a lower portion of the power tool gearbox. In addition, the transmission breather can be arranged to save space.

Advantageously, the switching element is a shift finger, which is rigidly connected to the driving element. As a result, the translational movement of the driving element is transmitted directly and without further losses by a deflection on the sliding element. By appropriate design of the shift finger, the switching unit can be adapted to different machine tools.

In an advantageous development, the switching element is a shift lever, which has a first arm, a second arm and an axis of rotation arranged therebetween, wherein the first arm is connected to the driving element, and wherein the second arm is provided for displacing the sliding element. Such a shift lever can contribute to achieving the desired overall reduction afford the switching unit. Through appropriate selection of the lever geometry, the switching unit can be adapted to various machine tool transmissions in a particularly flexible manner.

In another aspect, the invention relates to a machine tool transmission with a sliding element, which is translationally displaceable for switching the power tool gear in various switching positions, and with a switching unit for displacing the sliding element, wherein the switching unit is formed according to one or more of the preceding embodiments.

Advantages and developments of the machine tool transmission according to the invention will become apparent from the explanations of the switching unit according to the invention.

The invention is explained in more detail with reference to drawings. Show it:

FIG. 1 shows a schematic lateral sectional view of an embodiment of a switching unit according to the invention,

FIG. 2 shows an enlarged detailed representation of FIG. 1,

Figure 3 is a schematic front view of the switching unit of Figure 1 without

 Representation of a front-side housing part,

Figure 4 is a schematic bottom view of the switching unit of Figure 1 and

Figure 5 is a schematic side sectional view of an embodiment of a power tool gear according to the invention with a further embodiment of a switching unit according to the invention.

FIG. 1 shows a schematic lateral sectional view of an exemplary embodiment of a switching unit 1 according to the invention. This has an electric motor 2 with a shaft 3 shown schematically. The electric motor 2 may in particular be a DC motor 2. Other electric motor concepts, such as AC motors, three-phase motors, but are also conceivable. The electric motor 2 is followed by a likewise only schematically illustrated planetary gear 4, which in particular reduce the transmitted speed and the can increase transmitted torque. In this way, the desired overall reduction of the switching unit can be achieved in a simple, space-saving manner with good efficiency. A drive shaft 5 of the planetary gear 4 is arranged as well as an output shaft 6 of the planetary gear 4 coaxial with the shaft 3 of the electric motor 2. In this case, the drive shaft 5 of the planetary gear 4 can be rotatably connected by suitable means with the shaft 3 of the electric motor 2. It is also possible that the drive shaft 5 of the planetary gear 4 and the shaft 3 of the electric motor 2 are integrally formed.

On the output shaft 6 of the planetary gear 4, a first spur gear 7 is arranged rotatably, which meshes with a second spur gear 8. The second spur gear 8 in turn is in engagement with a third spur gear 9. The spur gears 7, 8, 9 form a spur gear 7, 8, 9, which in a simple way with good efficiency contributes to the desired overall reduction and in particular reduce the transmitted speed and can increase the transmitted torque. The third spur gear 9 is connected via a slip clutch 10 with a spindle 1 1. The spindle 1 1 is aligned parallel to the shaft 3 of the electric motor 2. As a result, between the electric motor 2 and the spindle 1 1 no complex transmission elements for the transmission of torque at an angle, such as bevel gears, Kardangetriebe or worm gear, necessary. In addition, such a high efficiency can be realized by low friction losses. Furthermore, the switching unit can be made so very compact.

The spur gear 7, 8, 9 allows in a simple manner a torque transmission over the parallel offset between the spindle 1 1 and the shaft 3 of the electric motor 2 away. As a result, as shown in Figure 1, the electric motor 2 and the spindle 1 1 are arranged side by side transversely to the axial direction, which allows a compact design by a reduced axial extent of the switching unit 1. In addition, the spur gear 7, 8, 9 can deliver in a simple manner with good efficiency a contribution to the desired overall reduction.

The spindle 1 1 has a thread 12 with which a driving element 13 is engaged. The entrainment element 13 is designed and mounted so that a rotation of the spindle 1 1 to a translational movement of the entrainment element tes 13 leads. As in the embodiment of Figure 1, the one-piece or multi-piece carrier element 13 may be designed as a driver plate 13.

In this case, fixed end stops 14, 1 5 are provided for limiting a movement of the driving element 13. In this way, small position tolerances result for the two end positions of the driving element 13. If the end positions correspond to switching positions, these can be taken very precisely, which allows an exact switching. The end positions can be adjusted, for example, by an exchange of the driving element 13 or not shown adjusting means, such as countered screws on the driving element 13, which can facilitate an adaptation of the switching unit 1 to various machine tools.

The driving element 13 is connected to a switching element 1 6, which is designed to move a sliding element of the respective power tool gear by it can transmit the translational movement of the driving element 13 on the sliding element. In Figure 1, the switching element 1 6 is a shift finger 1 6, which is rigidly connected to the driving element 13. As a result, the translational movement of the driving element 13 is transmitted directly and without further deflection-related losses on the sliding element. By a corresponding design of the shift finger 1 6, the switching unit 1 can be adapted to various machine tools. In the embodiment of Figure 1, this is a free end 17 of the shift finger 1 6 fork-shaped. A fork-shaped design of the free end of the shift finger is also possible in other embodiments.

Overall, it is thus possible to move by a corresponding control of the electric motor 2 of the switching unit 1, the sliding element between the switching positions in a direction of displacement VR, so as to switch the machine tool. The sliding element may in particular be a sliding sleeve, which, for example, is displaceable coaxially to a shaft, in particular to a drive shaft and / or an output shaft, of the power tool gear. In this case, the spindle 1 1 is aligned parallel to the intended displacement direction VR. As a result, the forces of the spindle 1 1 to the sliding element in be transmitted in a particularly simple manner. In particular, so the driving element 13 and / or the switching element 1 6 can be easily performed, which also comes to a space-saving design to the good. In addition, this is a high efficiency by low friction losses beneficial.

The proposed switching unit 1 can be made very compact overall. It can act on the sliding element along its entire possible movement with a substantially equal force, which allows a safe switching of the power tool gearbox. In this case, the transferable to the sliding elements forces can be many times higher than would be possible with comparable construction space and comparable power consumption with a solenoid. In addition, the switching unit 1 is self-locking, since the spindle 1 1 can not be offset by acting on the driving element 13 forces in rotation. Thus, further measures for locking the sliding element in one of the switching positions are unnecessary. Furthermore, the switching unit 1 is easily adaptable to various machine tool transmissions. For this purpose, it is sufficient in most cases that the switching element 1 6 is adapted to the shape and the arrangement of the switching element. Optionally, mounting adapter for fixing the switching unit 1 can be provided on a mounting portion of the power tool gearbox.

Figure 2 shows an enlarged detail view of Figure 1, wherein in particular the slip clutch 10 is shown. The slip clutch 10 is an automatic torque-switching safety clutch, which opens at least partially when a maximum torque is exceeded, so as to limit the torque output. In this way, ultimately the force on the switching element 1 6 is limited, which is particularly the avoidance of damage to the machine tool gearbox. The slip clutch 10 is arranged coaxially with the spindle 1 1. In this way, a particularly compact design of the switching unit can be realized with particularly good efficiency.

By way of example, the slip clutch 10 comprises two coaxially arranged to the spindle friction plates 18, of which at least one rotatably connected to the spindle 1 1 is connected. Furthermore, at least one of the friction plates 18 is loaded, so that a section of the third spur gear 9 is clamped between the two friction plates 18. If the torque to be transmitted does not exceed the maximum value, the torque is transmitted by static friction from the third spur gear 9 to the rotationally fixed friction plates 18 and from there to the spindle 1 1. If, on the other hand, the maximum torque is exceeded, then the static friction between the third spur gear 9 and the rotationally fixed friction disks 18 no longer suffices to transmit the torque, so that the clutch "slips", which causes a reduction of the transmitted torque.

Figure 3 shows a schematic frontal view of the switching unit 1 of Figure 1 without showing a front-side housing part. In addition to the spur gear 7, 8, 9, the shift finger 16 is shown in particular in FIG. In addition, Figure 3 shows a transmission vent 19, which serves to avoid an overpressure in the transmission, when, for example, warms the transmission. In this case, it should be avoided that through the gear vent 19 lubricants, such as oil or grease escape. If now, which is usual, the switching unit is arranged in an upper region of the power tool gearbox, just this goal can be achieved in a simple manner when the gear vent 19 is formed on the switching unit 1, since lubricants tend to be in a lower region of the power tool gear collect. In addition, the transmission vent 19 can be arranged to save space.

FIG. 4 shows a schematic bottom view of the switching unit 1 of FIG. 1. In particular, a first limit switch 20 is shown, which is actuated directly when it receives a first end position of the driving element 13. Likewise, a second limit switch 21 is shown, which is directly actuated by the driving element 13 when it assumes a second end position. The limit switches 20, 21 can be used to control the electric motor 2. In particular, the electric motor 2 can thus be switched off when one of the end positions is reached, without the need for elaborate electronics. If the end positions correspond to switching positions, they can be exactly taken and held in a simple manner. Furthermore, Figure 4 shows an intermediate switch 22 which is actuated directly by the driving element 13, when this has taken a corresponding intermediate position. Such a spacer switch 22 can also be used to control the electric motor 2. In particular, the electric motor 2 can thus be switched off when a defined intermediate layer is reached, without the need for elaborate electronics. Corresponds to the interposition of a switching position, so these can be taken exactly and held in a simple manner

FIG. 5 shows a schematic lateral sectional partial view of an exemplary embodiment of a power tool gear 23 according to the invention with a further exemplary embodiment of a switching unit 1 according to the invention.

The basic structure of the switching unit 1 of Figure 5 corresponds to the switching unit of Figures 1 to 4. The main difference is that no shift finger 16 but a shift lever 24 is provided.

The shift lever 24 has a first arm 25, a second arm 26 and an axis of rotation 27 arranged therebetween. In this case, the first arm 25 is connected to the driving element 13, and the second arm 26 with the sliding element 28. Such a shift lever 24 can contribute to achieving the desired overall reduction of the switching unit 1 afford. By appropriate selection of the lever geometry, the switching unit 1 can be adapted particularly flexibly to various machine tool transmissions 23.

Such machine tool 23 are used in lathes, milling machines but also in other machine tools. They serve in particular to increase the flexibility of the respective machine tool in the processing of different materials and / or different processing operations by varying the speed and / or torque. For this purpose, the machine tool transmission 23 has at least two translations, which can be selected by shifting the sliding element 28 into a switching position assigned to the respective gear ratio. In addition, a further switching position may be provided in which a transmission of torques is interrupted. Such a shift position is also referred to as a neutral position. The present invention is not limited to the illustrated and described embodiment. Variations within the scope of the claims are just as possible as a combination of features, even if they are shown and described in different embodiments.

Designation switch unit

electric motor

Shaft of the electric motor

planetary gear

Drive shaft of the planetary gear output shaft of the planetary gear first spur gear

second spur gear

third spur gear

slip clutch

spindle

thread

driving element

first stationary end stop second stationary end stop shift finger

free end of the shift finger

Friction discs of the friction clutch Transmission ventilation

first limit switch

second limit switch

Liner switch

Machine tools gear

gear lever

first arm

second arm

axis of rotation

Slide element shift direction

Claims

claims 1 . Switching unit for a power tool transmission (23), which has a sliding element (28) which is displaceable in various switching positions in a planned displacement direction (VR) for switching the power tool gear (23), characterized in that the switching unit (1) comprises an electric motor (2 ) comprising a shaft (3) which rotatably drives a spindle (11) provided with a thread (12), wherein the spindle (11) rotates by means of a rotation a driving element (13) which engages with the thread (12) moved in translation, wherein the entrainment element (13) with a switching element (16, 24) for moving the sliding element (28) is connected. Second switching unit according to the preceding claim, characterized in that the while (3) of the electric motor (2) and the spindle (1 1) are arranged parallel to each other. 3. Switching unit according to one of the preceding claims, characterized in that the spindle (1 1) is aligned parallel to the intended displacement direction (VR). 4. Switching unit according to one of the preceding claims, characterized in that between the electric motor (2) and the spindle (1 1) a spur gear (7, 8, 9) is provided. 5. Switching unit according to one of the preceding claims, characterized in that between the electric motor (2) and the spindle (1 1) a planetary gear (4) is provided. 6. Switching unit according to claim 5, characterized in that a drive shaft (5) of the planetary gear (4) and / or an output shaft (6) of the planetary gear (4) are arranged coaxially to the shaft (3) of the electric motor (2). 7. Switching unit according to one of the preceding claims, characterized in that between the electric motor (3) and the spindle (1 1) a slip clutch (10) is provided. 8. Switching unit according to claim 7, characterized in that the slip clutch (10) coaxial with the spindle (1 1) is arranged. 9. Switching unit according to one of the preceding claims, characterized in that stationary end stops (14, 15) are provided for limiting a movement of the driving element (13). 10. Switching unit according to one of the preceding claims, characterized in that at least one limit switch (21, 22) for detecting a receipt of an end position by the driving element (13) is provided. 1 1. Switching unit according to one of the preceding claims, characterized in that at least one intermediate position switch (22) for detecting an intake of an intermediate layer by the entrainment element (13) is provided. 12. Switching unit according to one of the preceding claims, characterized in that it comprises a transmission vent (19) 13. Switching unit according to one of the preceding claims, characterized in that the switching element (1 6; 24) is a shift finger (1 6) which is rigidly connected to the driving element (13). 14. Switching unit according to one of claims 1 to 12, characterized in that the switching element (1 6; 24) is a shift lever (24) having a first arm (25), a second arm (26) and an axis of rotation arranged therebetween ( 27), wherein the first arm (25) is connected to the driving element (13), and wherein the second arm (26) for displacing the sliding element (28) is provided. 15. Machine tool transmission with a sliding element (28) which is translationally displaceable for switching the power tool gear (23) in different switching positions and with a switching unit (1) for moving the sliding element (28), characterized in that the switching unit (1) after a the preceding claims is formed.