DE202022101707U1 - Conventional lathe - Google Patents

Abstract

Conventional lathe (D) with a main spindle (D21), which is driven by a main spindle motor (D11) with a motor controller (D12), and with a machine control (D5) in which at least
- a control parameter set of the motor control (D12) for a normal run-up (P _N ) of the main spindle (D21) with a clamping that has a normal mass moment of inertia on average,
- at least one control parameter set of the motor control (D12) for a soft start (P _S1 , P _S2 , P _S3 ) with reduced drive dynamics of the main spindle (D21) with a clamping that has an average at least increased mass moment of inertia,
- a period of time (t _m ) after activation (t=0) of the main spindle motor (D11), and
- At least one threshold value (M _S1 , M _S2 , M _S3 ) for the instantaneous torque (M _mom ) of the main spindle motor (D11), which corresponds to a set of control parameters for a soft run-up (P _S1 , P _S2 , P _S3 ) of the main spindle (D21) is assigned, wherein the machine control (D5) is designed so that this
- when the main spindle motor (D11) is activated (t=0), the motor control (D12) provides the control parameter set for the normal run-up (P _N ),
- in the period of time (t _m ) the instantaneous torque (M _mom ) monitored, and
- the motor control (D12) of the main spindle motor D11) instead of the control parameter set for the normal run-up (P _N ) provides a set of control parameters for a soft run-up (P _S1 , P _S2 , P _S3 ) for further run-up if during the time period (t _m ) in the _{instantaneous} torque (M _mom ) an exceeding of the threshold value ( _MS1 , _MS2 , _MS3 ) assigned to a set of control parameters for a soft run-up (PS1, _PS2 , _PS3 ) was detected.

Description

The invention relates to a conventional lathe

Under a conventional lathe is understood in the invention, a hand-controlled lathe without numerical control. Lathes of this type are described, for example, in DIN EN ISO 23125:2010-10 and are referred to there as type 1 machines. Such lathes are designed to be operated manually by one person and are equipped with simple controls. The operation of the machine is visually monitored by an operator. A conventional lathe is usually equipped with a feed screw to drive a bed slide on a machine bed. In addition, there is a main spindle motor for driving the main spindle, the rotation of which is transmitted to the main spindle by means of a mechanical transmission device, which usually contains a belt drive. In addition, a conventional lathe can be equipped with a lead screw, which drives the bed slide instead of the feed screw, especially in the thread cutting mode. Such a conventional lathe is for example from the DE 202019104050 U1 known.

In the following, the term clamping is understood to mean the sum of the clamping device currently attached to the main spindle and the workpiece held in it. Each setup has a mass moment of inertia due to its total mass and the distribution of the mass around the axis of rotation of the conventional lathe. In particular, the run-up behavior and the load on the main spindle motor, including the mechanical transmission device, are significantly influenced by this. The term mass moment of inertia for a rotating clamping, i.e. a clamping device with a workpiece, can also be abbreviated to mass inertia or inertia for the sake of simplicity.

Overload states of the drives and mechanics that occur during workpiece processing, e.g. caused by the specification of excessive feed speeds and cutting depths, can be recognized by an operator and eliminated with appropriate machine interventions. This is not possible when starting a conventional lathe. An operator can only intervene to avoid overloading after the conventional lathe has fully started up. Even experienced operators are not able to reliably estimate whether a simple, conventional lathe is likely to be overloaded during start-up with a certain setup.

Thus, when the main spindle of a conventional lathe is started up with a clamping that has at least an increased mass moment of inertia on average, high drive dynamics can be exerted on the main spindle motor by the motor control. Undesirably high mechanical loads can act on the components of the mechanical transmission device, e.g. a belt drive. These can result in increased wear, undesired slippage in the transmission device, e.g. slipping of the belt drive, and in extreme cases failure, e.g. tearing of the belt drive. The secure clamping of a workpiece in the clamping device can also be impaired and the workpiece can become detached.

Furthermore, during such a run-up, vibrations can also occur in the speed profile of the main spindle. Overshooting can occur in particular when the setpoint speed is reached. These can result in further wear in the conventional lathe. In particular, the completion of a run-up can be undesirably delayed as a result. Under certain circumstances, an operator then has to wait before beginning the machining of a workpiece until the speed fluctuations of the main spindle have subsided sufficiently and the main spindle speed can be regarded as largely constant.

These undesired effects occur to an increasing extent with the increase in the average mass moment of inertia to be accelerated by the main drive on the main spindle, i.e. when clamping with an increased, high or very high mass moment of inertia.

The invention is based on the object of specifying a conventional lathe in which the drive of the main spindle runs up quickly and with little wear, even when clamped with an increased mass moment of inertia.

The object is achieved with the conventional lathe specified in claim 1 . Advantageous further developments of the invention are specified in the respective dependent claims.

The device according to the invention relates to a conventional lathe with a main spindle, which is driven by a main spindle motor with motor control and has a machine controller.

The main spindle motor of a conventional lathe according to the invention is operated by a motor controller whose control parameters are stored in a machine controller. the Control and its control parameters are selected in such a way that the main spindle with the respective clamping device after activation, ie switching on the main spindle motor and starting with speed 0, reaches a desired speed as far as possible in an allocated run-up time. The motor control is thus preferably implemented as a speed control for the main spindle.

A conventional lathe according to the invention is a manual lathe without numerical control. Lathes of this type are described, for example, in DIN EN ISO 23125:2010-10 and are referred to there as type 1 machines. Such lathes are equipped with simple controls and are intended for manual operation by one person. The operation of the lathe is visually monitored by the operator. In practice, conventional lathes are often equipped with a feed spindle to drive the bed slide. A lead screw can also be present. This can be used to drive the bed slide after coupling it with a lock nut instead of the feed spindle, especially in the thread cutting mode.

According to the invention, a control parameter set for the motor control for the normal run-up of the main spindle with a setting that has a normal mass moment of inertia on average is stored in the machine control of the conventional lathe, as well as at least one control parameter set for a soft run-up with reduced drive dynamics of the main spindle with a set-up that has an im Medium has at least increased moment of inertia. A normal run-up or soft run-up can also be referred to as a run-up of the main spindle speed with a normal acceleration or soft acceleration.

In the case of the invention, a medium moment of inertia of a clamping is referred to as normal if this includes, for example, a standard chuck as clamping means and a workpiece with medium dimensions that is usually to be machined on a conventional lathe, for example a straight shaft with an average diameter. In the context of the invention, an average diameter is understood to mean a value which is approximately in the middle range of the maximum permissible swing diameter of workpieces above the cross slide which can be fixed on the main spindle of the respective conventional lathe. Furthermore, in the case of the invention, an average mass moment of inertia of a clamping is referred to as increased if this includes, for example, a face plate as clamping means and a workpiece with a larger diameter. This is because a faceplate has masses located at a greater radius from the center of rotation compared to a standard chuck. The same applies to an oversized workpiece with a larger diameter.

Furthermore, in a further, particularly advantageous embodiment of the invention, an average mass moment of inertia of a clamping is referred to as high if, for example, it includes a large face plate as clamping means and a workpiece with a large diameter and external masses, e.g. a pipe. Finally, in the case of the present invention, an average mass moment of inertia of a clamping is referred to as very high if, for example, it has the largest possible clamping device for the respective lathe and a workpiece with a very large diameter and very large external masses. An example of such a workpiece is e.g. a thick-walled tube, which has such a large diameter that it can be arranged over the cross slide with a small or smallest possible distance without collision.

It is particularly advantageous in the invention that the clampings that typically occur during the operation of a conventional lathe and their moments of inertia are classified in value ranges, i.e. at least in a value range for clampings with a normal mass moment of inertia on average, as well as another mass moment of inertia that is increased on average . In a further embodiment of the invention, the mass moments of inertia can advantageously be further structured in the case of particularly heavy clampings that deviate from the normal conditions, i.e. in value ranges for increased, high and very high mass moments of inertia. This gradual assignment of mass moment of inertia ranges to clampings that typically occur during the operation of a conventional lathe offers a particularly advantageous and simple way of improving the starting behavior of a conventional lathe according to the invention.

In the case of the invention, a set of control parameters for a normal run-up of the main spindle contains control parameters which are adapted for the acceleration of a clamping with a normal, ie average, mass moment of inertia on average. With these parameters, the motor control can approach the main spindle with such a clamping in a normal run-up time from standstill until a target speed is reached. The components involved in the mechanical torque transmission direction in the drive train of the conventional lathe, eg a drive belt, is stressed to a normal extent, ie largely low-wear and without dynamic overloads.

According to the invention, a set of control parameters for a soft start-up contains control parameters which are adapted for the acceleration of the main spindle with clampings which exceed an average mass moment of inertia for a conventional lathe. In this, the control parameters are adjusted in comparison to a set of control parameters for normal run-up in such a way that the motor control develops lower drive dynamics. There are smoother speed transitions of the main spindle with the fixture held on it between acceleration and deceleration sections, also called deceleration sections, as well as possible intermediate sections with constant acceleration. Due to the extended control and process times in this way, the occurrence of load peaks due to jerky control interventions is prevented, which would not be appropriate for accelerating clampings with increased mass moments of inertia on a conventional lathe.

According to the invention, a period of time is also stored in the machine control, which expires after activation of the main spindle motor. According to the invention, the duration of the period of time covers, beginning with a standstill, the first start-up phase of the main spindle motor with the setting in motion of the main spindle and the clamping fixed thereto.

In an advantageous embodiment of the invention, the period of time includes at least the tearing away phase of the main spindle immediately after activation of the main spindle motor. In a conventional lathe, the period of time may preferably be in the range of 200 to 800 milliseconds. Such a duration is expedient because, on the one hand, it is long enough for the monitoring of the instantaneous torque according to the invention and, on the other hand, it is as short as possible so that the main spindle is mainly accelerated using a set of control parameters suitable for the respective mass inertia, i.e. either continue to use the normal startup or for a soft startup.

According to the invention, at least one threshold value for the instantaneous torque of the main spindle motor is also stored in the machine control and assigned to a control parameter set for a soft start-up of the main spindle. The threshold value for the instantaneous torque represents a limit. This is advantageously selected in such a way that if it is exceeded, the effect of a set of control parameters for a soft start-up of the main spindle on the motor control would lead to a more favorable start-up behavior with reduced drive dynamics for the conventional lathe.

In order to achieve this, the machine control according to the invention is designed in such a way that when the main spindle motor is activated, it initially provides the motor control with the set of control parameters for normal run-up and monitors the instantaneous torque in the period of time, particularly immediately after activation. If, during the period of time, the machine controller detects that the threshold value assigned to the control parameter set for a soft start-up has been exceeded in the instantaneous torque, the motor control of the main spindle motor is provided with the control parameter set assigned to the exceeded threshold value for a soft start-up for the further start-up instead of the control parameter set for normal start-up .

The period of time can be selected so that it is long enough to determine a representative torque curve and as short as possible so that the main spindle is only accelerated for a very short time using a set of control parameters that may be unsuitable.

In the case of the invention, the main spindle motor is thus activated regularly in such a way that the control parameter set for normal run-up is first provided by the machine control and processed by the motor control. The lathe starts from standstill with such boundary conditions. In the normal case, i.e. in the case of a clamping with a normal mass inertia on average, these are suitable and lead to a run-up in the desired manner without overloading the machine. If, on the other hand, a violation of the threshold value is detected, after the time period has expired, i.e. as quickly as possible after activation, the control parameter set in the engine control system is replaced by the machine control system with a control parameter set for a soft start-up. The lathe starts up only briefly after activation with an unfavorable set of parameters, so that machine overloads can hardly have any effects. The predominant further part of the run-up then takes place under the influence of a more favorable set of parameters with reduced drive dynamics.

When the main spindle is activated, it is initially set in rotation by the main spindle motor with a set of control parameters for a normal run-up. During the period that will The instantaneous torque generated by the main spindle motor using the set of control parameters for a normal run-up and transmitted to the main spindle is recorded and recorded by the machine control system. The term instantaneous torque is understood to mean the current actual torque value which is applied by the main spindle motor in particular to accelerate the main spindle with a clamping device attached to it when the machine is started up. If the course of the instantaneous torque recorded during the period of time shows that a stored threshold value is exceeded, the machine control in the controller of the main spindle motor replaces the set of control parameters for a normal run-up with the set of control parameters assigned to this threshold value for a soft run-up and the acceleration of the main spindle with this set of control parameters continued for a smooth run-up until the desired speed is reached. The maximum torque of the main spindle motor that occurs during the period of time with a control parameter set for a normal run-up thus serves as an indicator for the mass inertia of the clamping to be accelerated, so that after the period of time has elapsed, a control parameter set suitable for the derived mass inertia of the respective clamping is transferred from the machine control to the controller and the acceleration is continued with this set of control parameters. In this way, the acceleration behavior and the dynamics of the main spindle motor are individually adapted and harmonized to the mass inertia of the respective clamping.

Advantageously, the control parameter set that was recognized as optimal with the help of the invention during the period of time, i.e. the original control parameter set for normal startup or an exchanged control parameter set for soft startup, is also retained for the further operation of the conventional lathe and the implementation of the intended workpiece machining.

The invention offers the particular advantage that a low-wear run-up of a conventional lathe is also possible automatically if a machine operator does not notice the presence of a clamping with an undesirably high mass moment of inertia or cannot estimate the extent thereof. The invention enables the machine controller to monitor the type of clamping on the main spindle in the period of time, in particular immediately after the activation of the main spindle motor. According to the invention, the torque currently applied by the motor control, particularly in the breakaway phase after the activation of the main spindle motor, is monitored in order to set the main spindle and clamping device in motion. From this, the machine control can deduce whether the respective clamping is normal, with a mass moment of inertia that can be considered normal on average, or unusual, with a mass moment of inertia that can be considered excessive on average, and can set optimal drive dynamics by adapting the control parameter set.

In particular, the occurrence of load peaks in the transmission device between the main spindle motor and the main spindle and the wear are advantageously reduced on a lathe according to the invention. Furthermore, the harmonization of the acceleration reduces vibrations in the speed profile of the main spindle. As a result, the wear on a lathe according to the invention is advantageously further reduced. Furthermore, an after-oscillation of the speed after completion of the run-up of the main spindle is advantageously reduced, so that the run-up can be completed more quickly and machining of the clamped workpiece can be started more quickly.

The invention offers a significant improvement in the start-up behavior of a conventional lathe and relieves the strain on the operating personnel. Without the development according to the invention, this would have to abort a heavy start-up of a conventional lathe if you notice it at all. If possible, an attempt should then be made to reduce the mass moment of inertia of a clamping by modifying the main spindle. Otherwise, the machining of the workpiece would have to be shifted to a more powerful lathe. This can be avoided with the invention.

In a particularly advantageous development of the conventional lathe according to the invention, the motor controller exerts accelerations on the main spindle motor with a lower gradient than in the control parameter set for a normal run-up to generate reduced drive dynamics in a set of control parameters for a soft run-up. This embodiment of the invention offers the advantage that the reduction in the drive dynamics in the case of a soft run-up is brought about by limiting the rate of change of accelerations of the main spindle motor.

In a further advantageous embodiment of the conventional lathe according to the invention, a set of control parameters for a soft start-up, which is used for clamping, is stored in the machine control in order to exert reduced drive dynamics on the main spindle is assigned to the main spindle, which has an increased, high or very high mass moment of inertia on average, and a threshold value in each case, which is assigned to a set of control parameters for a soft run-up, and the size of which increases with the mass moment of inertia of the respective clamping. Several control parameter sets for soft start-up are therefore stored in the machine control. Each set of control parameters is optimized for a different clamping category. A control parameter set for a clamping with an average high moment of inertia, a control parameter set for a clamping with an average high mass moment of inertia and a control parameter set for a clamping with an average very high moment of inertia are therefore advantageously available.

The assignment of a set of control parameters for a smooth run-up to a respective associated torque threshold value advantageously enables the activation of a set of control parameters in the engine controller that is specially adapted for the moment of inertia of a more massive clamping. In particular, an advantageous size gradation of threshold values of a group makes it possible to classify the size of the instantaneous torques that occur in each case. If, in the period of time after the activation of the main spindle motor, it is detected that the instantaneous torque exceeds a larger of several threshold values, this is an indication of clamping with a correspondingly increased mass moment of inertia. In such a case, the invention makes it possible to replace the set of control parameters for normal run-up with a specifically selected set of control parameters that is particularly suitable for clamping with an increased, high or very high mass moment of inertia on average. This means that the soft start-up of a conventional lathe can be carried out automatically with little wear and without intervention by an operator, even when clamping with possibly strongly fluctuating mass moments of inertia.

In the above embodiment of the conventional lathe according to the invention, it can also be advantageous if the motor controller exerts a decreasing gradient in the acceleration on the main spindle with an increase in the mass moment of inertia of the clamping on the main spindle in order to exercise reduced drive dynamics with a control parameter set for a soft run-up. Particularly advantageously, the gradient can be selected as a function of the ratio of the moment of inertia in a setting with a normal moment of inertia to the moment of inertia of a setting with an increased, high or very high moment of inertia.

This offers the advantage that a gradient decrease can be adapted to a respectively existing ratio of a mass moment of inertia that is considered normal to an excessive mass moment of inertia. Special structural features and the performance of a respective conventional lathe are also included in the parameterization.

In a further advantageous embodiment of the conventional lathe according to the invention, the motor control contains a controller with at least one P component and one I component. An associated set of control parameters for a soft run-up then advantageously has an increased reset time and an increased amplification factor in comparison to a set of control parameters for a normal run-up to reduce the drive dynamics.

In this advantageous embodiment of the invention, the control parameters for a soft run-up have, as a control variable, a longer reset time than the set of control parameters for a normal run-up. For this purpose, the I component is usually reduced in a PI controller. In this way, the dynamics of the motor control can be reduced and the control behavior can be harmonized during a start-up phase and in particular during a deceleration or braking phase when the desired speed of the main spindle is approached. Particularly advantageously, the control parameters for a soft run-up as the controlled variable in this embodiment also have a greater amplification factor than the set of control parameters for a normal run-up. For this purpose, the P component is usually increased in a PI controller. In this way, the value of the approximately uniform acceleration of the main spindle between a start-up phase and a deceleration phase can be increased. All in all, by simultaneously increasing the reset time and amplification factor, the total time until the speed of the main spindle is reached can be largely maintained in many cases, despite gentler start-up and deceleration phases. The loss of time that occurs in the start-up and deceleration phases due to an increased reset time can be made up for in an intervening linear phase with largely constant acceleration due to the increased amplification factor.

The gain factor and reset time parameters are used to advantage in a control parameter set for classic motor control with a PI controller. If required, the set of control parameters can also have an additional D component in the case of a clamping with a particularly high mass moment of inertia. For example, control parameter sets for a soft start, which, according to a further embodiment of the invention that has already been explained, are assigned threshold values of increasing size, also have increasing D components. A D component causes a further reduction in the drive dynamics in the event of heavy starting of a clamping with a particularly high mass moment of inertia, particularly when the main spindle motor is activated or switched on.

In other versions of a motor control for the main spindle motor, e.g. a digital control, the control parameters that are essential to the invention are adapted accordingly, especially in a set provided for a soft start-up.

The machine control is particularly advantageously designed in such a way that the main spindle motor is shut down with the set of control parameters that is active in the motor control. In this version, the set of control parameters that is active in the motor control after the end of a run-up, e.g. for normal run-up or a soft run-up, is also active when the lathe is shut down until it comes to a standstill. Only when restarting, before which a workpiece change with a change in the mass moment of inertia of the clamping may have occurred, is the motor control reset to the initial state by reactivating the control parameter set for the normal run-up of the main spindle.

In an advantageous further embodiment of the invention, the machine control is designed such that in the thread cutting mode and activation of the main spindle motor after an interim standstill, the main spindle is run up without monitoring the current torque with the control parameter set active in the motor control.

The production of a thread in a workpiece with a desired quality and required parameters using a lathe often requires several machining operations. Between these, the operator stops the rotation of the main spindle, repositions the tool on the workpiece for the next machining step and also frequently carries out control measurements. The main spindle then starts up again in order to continue or complete the machining of the thread.

If the conventional lathe according to the invention is in the thread turning operating mode, this embodiment offers the advantage that the set of control parameters effective before the main spindle was temporarily stopped also remains active. Each time the main spindle is run up for a further machining step, a possibly unsuitable set of control parameters is not started and the suitable set of control parameters is determined again. Since the machining is carried out on the same workpiece and the mass moment of inertia of the clamping is unchanged, the original control parameter set can remain active. In this way, load peaks occurring in particular during the period of time are advantageously reduced and the wear on a lathe according to the invention is reduced.

A conventional lathe is often equipped with at least one feed spindle for driving a bed slide. Such a conventional lathe can be particularly advantageously additionally equipped with at least one lead screw for driving a bed carriage in the thread cutting mode, and with a lock nut which is in engagement with the lead screw in the thread cutting mode. In the thread cutting mode, the bed slide is not driven by the feed spindle, but by the lead screw and lock nut.

In an advantageous further development of the conventional lathe according to the invention, the machine control is advantageously designed in such a way that in the thread cutting mode, a standstill of the main spindle and a disengagement of the lock nut are detected and the main spindle motor is restarted after renewed activation by the motor control with the control parameter set for normal run-up becomes.

In the thread cutting mode, the bed slide is not driven by the feed spindle, but by the lead spindle and lock nut. Disengagement of the nut is performed by an operator after the threading operation is complete and before the workpiece is unclamped from the lathe. It is no longer necessary to keep the previously active control parameter set, e.g. a control parameter set for a soft start. According to the invention, the machine controller detects this change in the state of the lock nut and activates the set of control parameters for a normal run-up. A set of control parameters for a soft start that may have been activated at the start of thread cutting and when the main spindle is started up is thus overwritten and reset.

• 1 eine beispielhafte, gemäß der Erfindung ausgeführte konventionelle Drehmaschine D in einer schematischen Frontalansicht,
• 2 ein beispielhaftes, schematisches Funktionsbild des erfindungsgemäßen Zusammenwirkens der Maschinensteuerung D5 mit dem Hauptspindelmotor D11 in einer erfindungsgemäßen konventionellen Drehmaschine D,
• 3 vier beispielhafte Zeitverläufe L1, L2, L3, L4 des Momentan-Drehmoments M_mom des Hauptspindelmotors D11 während der Zeitspanne t_m nach Aktivierung der Hauptspindel für Aufspannungen mit unterschiedlichen Massenträgheitsmomenten, und
• 4 ein Drehzahl-Zeit-Diagramm für die Momentan-Drehzahl der Hauptspindel mit drei beispielhaften Zeitverläufen K1, K2, K3 der Drehzahl U der Hauptspindel für unterschiedliche Aufspannungen und Regelparametersätze.

The conventional lathe according to the invention as well as advantageous further versions of the same are explained in more detail below with reference to the briefly cited figures. while showing

• 1 an exemplary conventional lathe D designed according to the invention in a schematic front view,
• 2 an exemplary, schematic functional diagram of the inventive interaction of the machine control D5 with the main spindle motor D11 in a conventional lathe D according to the invention,
• 3 four exemplary time profiles L1, L2, L3, L4 of the instantaneous torque M _mom of the main spindle motor D11 during the period t _m after activation of the main spindle for clamping with different moments of inertia, and
• 4 a speed-time diagram for the instantaneous speed of the main spindle with three exemplary time curves K1, K2, K3 of the speed U of the main spindle for different clampings and control parameter sets.

1 12 shows an exemplary conventional lathe D according to the invention. A headstock D2 and a machine bed D3 are arranged on a machine frame D1. A bed slide D4 is located on the machine bed D3. This can be moved along the machine bed D3 in a z-axis, which is in the plane of the drawing 1 runs. The bed slide carries a cross slide D41, which can be moved in an x-axis. This runs orthogonally to the z-axis, ie perpendicular to the plane of the page 1 . Finally, on the cross slide there is a tool D42 for machining an in 1 not shown workpiece attached. In the exemplary machine shown, the bed carriage is advantageously driven in the z-axis by means of a feed spindle D31. This runs along the bed slide and is driven by a drive in the headstock D2. Depending on the design of the conventional lathe D, a separate drive is provided for this purpose, or torque is derived, for example, from the main spindle motor D11 via a gear. The conventional lathe D in the example 1 is advantageously also equipped with a lead screw D32. This can be brought into engagement with the bed slide D4 in place of the feed spindle, especially in the thread cutting mode, and enables traversability in the z-axis on the machine bed D3. Feed screw D31 and lead screw D32 are in 1 shown schematically by a thick line.

The conventional lathe D has a main spindle D21 which is rotatably mounted in the headstock D2. At the front end of the main spindle D21, in the representation of 1 facing the machine bed D3, there is a clamping means D22 for a workpiece. Depending on the type of workpiece, its dimensions and mass moment of inertia, different clamping devices are used to hold the workpiece. So is in 1 a chuck is shown schematically as a clamping device by way of example. Such a mass moment of inertia usually has, on average and in comparison to other clamping means, that in the case of the present invention, for example, can be described as normal. Collets can also be used as clamping devices in the main spindle D21, which can have a lower mass moment of inertia compared to a chuck. Furthermore, a faceplate can be fastened to the main spindle D21 as a clamping device, which, in comparison to a chuck, can also have a mass moment of inertia that is referred to as being increased.

The lathe D has a particular speed-controlled main spindle motor D11, whose rotation via a transmission device, which in the example 1 is designed as a belt drive D14, is transmitted to the main spindle D21. The main spindle motor D11 has a motor controller D12 and advantageously also a tachometer D13. These are in 1 shown as attachments to the main spindle motor D11. The speed of the main spindle motor D11 can be regulated by means of the motor control D12. As a result, the power consumption of the main spindle motor D11 is adjusted as a function of the load so that the speed of the main spindle D11 assumes a desired course, especially when ramping up after a machine start, and is as constant as possible for the duration of workpiece machining when the target speed is reached. The turning machine D also has a machine controller D5 which is coupled to the main spindle motor D11 via a data link D51. In this way, for example, control parameter sets stored in the machine control D5 can be transmitted to the motor control D12. With these, the speed behavior of the main spindle motor can be adapted to different operating states of the conventional lathe, in particular depending on the mass moment of inertia of the respective clamping.

The conventional lathe according to the invention and the method according to the invention for operating such a lathe are illustrated in the schematic sketch in 2 illustrated. The inventive interventions of the machine controller D5 after activation and when the main spindle motor D11 is started up are visualized as an example using data communication via a data connection D51 between the machine controller D5 and the motor controller D12 of the main spindle motor in a model with three exemplary steps.

According to the invention, at least one control parameter is stored in the machine control D5 Substitute for a normal run-up P _N of the main spindle D21 and an adjustable period of time t _m , in which, after the activation of the main spindle motor D11, the course of the instantaneous torque M _mom emitted by the main spindle motor is recorded and monitored. Furthermore, according to the invention, at least one further set of control parameters for a soft start-up of the main spindle with reduced drive dynamics and a threshold value M _S1 assigned to this set of control parameters for the instantaneous torque M _mom of the main spindle motor D11 are stored.

In the case of the sketch of 2 In the example shown, three sets of control parameters P _S1 , P _S2 and P _S3 for smooth acceleration of the main spindle are particularly advantageous in the machine control D5, as well as an associated threshold value M _S1 , M _S2 or M _S3 for the instantaneous torque M _mom of the main spindle motor D11 for each set of control parameters deposited. This design offers the advantage that, depending on an increase in the mass moment of inertia of the clamping, a particularly suitable set of control parameters P _S1 , P _S2 or P _S3 is activated for a smooth start-up in the motor control and a graded, particularly gentle drive dynamic can be achieved. This is shown below in the curves of 3 and 4 be explained in more detail.

The specification of the at least one threshold value is carried out according to the invention, in particular taking into account a mass to be accelerated by the main spindle motor, i.e. is dependent in particular on the inertia of the respective clamping device and a workpiece held by it. In particular, the size of the selected threshold depends on the performance of the main spindle motor, i.e. the ability to provide a specific motor torque. A threshold value enables the machine controller to detect whether the mass moment of inertia of a current clamping is still considered normal or already increased, and whether a ramp-up can still be managed with a control parameter set for a normal ramp-up or advantageously the or a selected control parameter set for a soft ramp-up is to be activated.

An exemplary interaction of the machine control D5 with the motor control D12 of the main spindle motor D11 according to the invention is illustrated using exemplary steps 1, 2 and 3 in 2 explained in more detail. The symbol in the upper area of the 2 dashed arrow running from D5 to D12 step 1, the dashed arrow running in the middle from D12 to D5 step 2 and the dashed arrow running in the lower area from D5 to D12 step 3.

Step 1 concerns the operations when the main spindle motor D11 is activated. When the main spindle motor is switched on at time t=0, the machine control D5 transmits the control parameter set for a normal run-up P _N via the data connection D51 to the motor control D12 of the main spindle motor D11 and the time period t _m is started. The run-up of the main spindle thus begins initially under the direction of the set of control parameters for a normal run-up P _N .

Step 2 concerns the processes during the period t _m , ie the period 0 < t < t _m . The motor controller D12 continuously transmits the values of the instantaneous speed U _mom of the main spindle motor D11 determined by the tachometer D13 and the instantaneous motor current I _mom recorded by it via the data connection D51 to the machine control D5. From this, the course of the instantaneous torque M _mom (t) as a function of time is determined by the machine control D5.

Step 3 concerns the operations after the lapse of the period t _m , ie the period t > t _m . When the period of time t _m has elapsed, an evaluation of the detected torque-time curve is preferably carried out in the machine controller D5. If this does not exceed the threshold value M _S1 in the time period 0<t<t _m or, according to an advantageous further embodiment of the invention, a threshold value M _S1 < _MS2 or < _MS3 , the main spindle is further accelerated until the run-up is complete when the desired spindle speed is reached by the motor control D12, it continues with the control parameter set for a normal run-up P _N . This is possible because if the curve of the instantaneous torque continuously falls below the threshold value, this is an indication that the clamping can be regarded as normal and that the intervention of the control parameter set for a normal run-up _PN is advantageous for the end of the run-up. This is in the lower area of 2 expressed by M _mom < M _S1 / M _S2 / M _S3 : P _N .

If, on the other hand, it is detected that a threshold value is exceeded in the torque-time curve, i.e. in the instantaneous torque, the control parameter set assigned to this threshold value for a soft run-up P _S1 is transmitted by the machine control D5 via the data connection D51 to the motor control D12 of the main spindle motor D11. The control parameter set for normal run-up that is briefly active when the main spindle starts up is thus overwritten and the run-up is thus completed with reduced drive dynamics.

According to a further embodiment of the invention, a set of threshold values can also be present, for example the threshold values M _S1 , M _S2 or M _S3 . In this case, each threshold value is assigned a set of control parameters for a soft run-up P _S1 , P _S2 or P _S3 , which is advantageously adapted to a clamping with an increased, high or very high mass moment of inertia on average. If it is detected that such a threshold value is exceeded in the course of the instantaneous torque, the assigned set of control parameters for a smooth run-up is transmitted by the machine control D5 via the data connection D51 to the engine control D12. The selection of that set of control parameters for a soft start P _S1 , P _S2 or P _S3 and its transmission from the machine control D5 via the data connection D51 to the engine control D12 that is assigned to the highest exceeded threshold value M _S1 , M _S2 or M _S3 is particularly advantageous. This is illustrated using the exemplary course in 3 be explained in more detail. The set of control parameters for a normal run-up P _N stored in the machine control D5 and processed during the time period t _m is replaced by the selected set of control parameters for a soft run-up P _S1 , P _S2 or P _S3 and the acceleration of the main spindle with processing of this set of control parameters until the run-up is complete of the main spindle when the desired spindle speed is reached. this is in 2 expressed below by M _mom > M _S1 / M _S2 / M _S3 : P _S1 / P _S2 / P _S3 .

The invention offers the advantage that due to the monitoring of the instantaneous torque of the main spindle motor in the period of time, i.e. the particularly high torque to be applied by the main spindle motor at the beginning of the acceleration of the main spindle, a conclusion can be drawn about the mass moment of inertia of the respective clamping of the clamping device and workpiece on the main spindle is possible, and then an adapted set of control parameters can be used for a more harmonious soft start-up of the main spindle with reduced drive dynamics. In this way, peak loads, in particular in the transmission device, and the wear on a lathe according to the invention are reduced.

In an advantageous further embodiment of the invention, the machine control is also designed such that in the thread-cutting operating mode, the main spindle continues to be operated after a standstill with the control parameter set that was effective before the standstill. When the thread cutting mode is activated in the machine control and the clamping is accelerated for the first time, a selection and activation of a set of control parameters takes place in the manner according to the invention. Depending on the masses to be accelerated, the set of control parameters for a normal run-up P _N is active or replaced by the set of control parameters for a soft run-up P _S1 , P _S2 or P _S3 . This set of control parameters is also processed after the main spindle has been stopped in the meantime and the clamping has been accelerated again, as long as the thread cutting mode is activated in the D5 machine control. This embodiment offers the advantage that the set of control parameters selected with the aid of the invention can remain active over a longer period of time. The machining of a thread or the repeated production of threads, in particular of the same type on the same workpiece, can be carried out quickly without intermittent standstills of the lathe causing the time period to expire again and repeated threshold value monitoring of the course of the instantaneous torque.

In the 1 The conventional lathe D shown according to the invention also has a lead screw D32 and a lock nut D43 in the bed carriage D4. In this way, in the thread-cutting operating mode, the lead screw D32 is brought into engagement with the bed slide D4 instead of the feed screw D31. According to an advantageous further embodiment, the machine control D5 is designed such that in the thread-cutting operating mode the main spindle D21 is only started up after the lock nut has come to a standstill and has been disengaged with a set of control parameters for a normal run-up. A reset of the motor control to the set of control parameters for a normal run-up is therefore only carried out by detecting the disengagement of the lock nut after the thread-cutting process has been completed.

3 shows a sketch of four example time curves L1, L2, L3, L4 for the curve of the instantaneous torque M _mom of the main spindle motor D11. These begin with the activation of the main spindle motor at time t1 = 0, ie with step 1 of 2 . During the period of time t _m these are in step 2 of 2 monitored to see whether their curves exceed the threshold value M _S1 , M _S2 or M _S31 . Depending on this, at the end of the time period t _m in step 3 of 2 determined by the machine control whether the set of control parameters for the normal run-up P _N can be retained or is to be exchanged for a set of control parameters for a soft run-up P _S1 , P _S2 , P _S3 .

The exemplary torque curve L1 occurs when accelerating a clamping that has a normal mass moment of inertia. This has a linear initial range in which the main spindle motor using the control parameter set for a normal run-up P _N Torque builds up, and an arcuate area with a maximum value that can be assigned to a breakaway torque M _N , and in which static friction between the components of the spindle drive is to be overcome. In the further degressive range, the further acceleration of the clamping takes place. The torque curve L1 does not exceed the first threshold value M _S1 during the period of time t _m , so that the set of control parameters for the normal run-up P _N continues to be applied after the period of time t _m has elapsed.

The exemplary torque curve L2 occurs when accelerating a clamping that has an increased mass moment of inertia on average. The linear initial range, in which the main spindle motor builds up torque using the set of control parameters for a normal run-up P _N , has a greater gradient than torque curve L1 because of the higher mass inertia. The maximum value and the subsequent declining range are also higher. In the period of time t _m at the point of intersection U1, the torque curve L2 exceeds the threshold value M _S1 , which is assigned to a set of control parameters for a smooth run-up P _S1 . After the time t _m has elapsed, ie after the in 3 Dashed vertical line, the control parameter set P _N is overwritten by the control parameter set P _S1 in the motor control and the run-up is continued with reduced drive dynamics.

The exemplary torque curve L3 occurs when accelerating a clamping that has a high mass moment of inertia on average. The linear initial range, in which the main spindle motor builds up torque using the control parameter set for a normal run-up P _N , has a greater slope than the torque curve L2 due to the higher mass inertia. The maximum value and the subsequent declining range are also higher. In the time period t _m , the torque curve L3 exceeds the threshold value M _S1 at the point of intersection U21, which is assigned to a control parameter set for a soft start-up P _S1 , and at a further point of intersection U22 the threshold value M _S2 , which is assigned to a control parameter set for a soft start-up P _S2 . After the time t _m , ie at the in 3 Dashed vertical line, the control parameter set P _N is overwritten according to the invention by the control parameter set P _S2 in the motor control and the run-up is continued with a further reduced drive dynamics.

The exemplary torque curve L4 occurs when accelerating a clamping that has a very high mass moment of inertia on average. The linear initial range, in which the main spindle motor builds up torque using the control parameter set for a normal run-up P _N , has an even greater slope than the torque curve L3 due to the higher mass inertia. The maximum value and the subsequent declining range are also higher. During the period of time t _m , the torque curve L4 exceeds the threshold value M _S1 , which is assigned to a control parameter set for a soft start-up P _S1 , at the point of intersection U31, and at a further point of intersection U32 the threshold value M _S2 , which is assigned to a set of control parameters for a soft start-up P _S2 , and Finally, at the point of intersection U33, the threshold value M _S3 , which is assigned to a set of control parameters for a soft run-up P _S3 . After the time t _m , ie at the in 3 Dashed vertical line, the control parameter set P _N is overwritten according to the invention by the control parameter set P _S3 in the motor control and the run-up is continued with a particularly greatly reduced drive dynamics.

In the case of the conventional lathe according to the invention, a gradual application of pre-programmed sets of control parameters therefore takes place depending on the mass moment of inertia of the respective clamping. These are each matched to a mass inertia range, i.e. to ranges with e.g. normal, increased, high or very high mass moments of inertia on average, and result in a smooth run-up with decreasing drive dynamics. This has the advantage that the machine control system does not require any computing power-intensive interpolation of an individual control parameter set that is matched to the value of a clamping to be accelerated. Rather, the exchange according to the invention of stored control parameter sets, as described above, can also be carried out quickly by the simple control of a conventional lathe.

4 shows a time diagram for exemplary courses of the instantaneous speed U of the main spindle in a conventional lathe D according to the invention. Exemplary run-up curves for the acceleration of the main spindle are shown for different clampings and control parameter sets.

The run-up curve K1 with a thick continuous line thus illustrates a normal case of the acceleration of the main spindle. The clamping has a normal mass moment of inertia and contains, for example, a conventional chuck as the clamping device and a shaft as the workpiece. The run-up curve starts at the origin with the activation of the main spindle motor at time t1=0 and the speed 0. The control parameter set for a normal run-up P _N is processed by the motor control.

In the period of time t _m between the times t1 and t2, the instantaneous torque U _mom of the main spindle motor is monitored in a manner according to the invention. In the run-up curve K1, it is assumed that no threshold value for the instantaneous torque of the main spindle motor, which is assigned to a set of control parameters for a soft run-up, is exceeded during the time period t _m . This is with the example of the torque-time curve L1 in 3 described condition comparable. At the end of the time period t _m , ie from the point in time t2, the acceleration of the main spindle can thus be continued in an unchanged manner while processing the set of control parameters for a normal run-up P _N .

The exemplary run-up curve K1 has an acceleration section K11 between the times t1 and t3. The torque is built up by the main spindle motor, the starting inertia of the transmission elements and clamping as well as the static friction in the spindle drive are overcome. Since the associated mass moment of inertia is assumed to be normal in the example of run-up curve K1, the torque applied by the main spindle motor does not cause any unreasonably high loads in the transmission device. Between times t3 and t6, there follows a linear segment K12, in which the speed of the main spindle increases approximately linearly. Between times t6 and t7, a deceleration or deceleration section K13 follows, in which, shortly before the target speed U _is reached, the torque of the main spindle motor and thus the acceleration of the clamping are reduced. At the point in time t7, the desired speed U desired of the main spindle _, which has been preselected by an operator, is approximately reached. The period of time between times t1 and t7 corresponds to the run-up time t _h of the main spindle desired by an operator until the setpoint speed U setpoint _is reached.

In practice, after the run-up time t _h and the formal completion of the run-up of the main spindle, a post-oscillation section K14 usually follows. In this, the speed U of the main spindle oscillates by the value of the setpoint speed U set for the duration of a post-oscillation time t _n due _to the mass moment of inertia of the clamping and its previous deceleration. In the example of the run-up curve K1, the post-oscillations of the main spindle speed run within a tolerance range Ut between an upper and lower tolerance speed Uto and U _tu , and subside within an acceptable post-oscillation time t _n . The machining of a workpiece can thus begin at point in time t7 at the end of run-up time t _h .

The run-up curve K2 in 4 illustrates with a thin dashed line an example of a problem when accelerating the main spindle. In this case, a clamping with an increased mass moment of inertia, for example a faceplate as a clamping device and a workpiece with a larger diameter, is run up while processing an unsuitable set of control parameters for a normal run-up P _N . The run-up curve begins at the origin of the diagram with activation of the main spindle motor at time t1=0 and speed 0. The control parameter set for a normal run-up P _N is processed by the motor control. In the acceleration section K21 between times t1 and t3, the main spindle motor delivers such a high torque boost due to the control parameter set processed by the motor control for a normal run-up P _N that the clamping is accelerated with approximately the same dynamics as in the run-up curve K1. The run-up curves K1 and K2 thus run approximately congruently between the times t1 and t3. The torque thrust delivered by the main spindle motor causes undue stress and excessive wear, particularly in the transmission.

An almost uniformly increasing linear section K22 follows, in which the speed of the main spindle increases almost linearly. Due to the same processed set of control parameters for a normal run-up P _N between the times t3 and t6, this likewise runs approximately congruently with the run-up curve K1. Between the points in time t6 and t7 there follows a deceleration or braking section K23, in which, shortly before the target speed U _is reached, the torque of the main spindle motor and the acceleration of the clamping are to be reduced. Due to the increased mass moment of inertia of the clamping, the reduction in torque is not sufficient, so that strong post-oscillation of the instantaneous speed U _mom occurs in the post-oscillation section K24. These are in 4 clearly seen in dashed line after time t7. The speed oscillates outside a tolerance range Ut around the target speed U set _, with the upper and lower tolerance speeds Uto and Utu being exceeded. An operator must wait a long post-oscillation time t _n before the post-oscillations of the main spindle speed have died down and machining of a workpiece can begin. this is in 4 no longer shown. Active braking via the motor control of the main spindle motor may be necessary. This has a force effect that counteracts the acceleration of the main spindle, so that the load on the components of the spindle drive, especially the transmission device, is further increased. Furthermore, the speed of the main spindle can again _be stimulated to post-oscillate around the target speed U desired .

The run-up curve K3 in 4 finally, with a thin continuous line, an example of the solution according to the invention to the problem represented by the run-up curve K2 by processing a set of control parameters for a soft run-up P _S1 instead of one for a normal run-up P _N . The run-up curve begins at the origin of the diagram with activation of the main spindle motor at time t1=0 and speed 0. The motor control first processes the set of control parameters for a normal run-up P _N . In the period of time t _m between the times t1 and t2, the instantaneous torque U _mom of the main spindle motor is detected in a manner according to the invention. In the case of the run-up curve K3, it is assumed that a threshold value for the instantaneous torque of the main spindle motor, which is assigned to a set of control parameters for a soft run-up, is exceeded during the time period t _m . This is with the example of the torque-time curve L2 in 3 described condition comparable. At the end of the period of time t _m , ie at time t2, the control parameter set for soft start-up is transmitted from the machine control to the motor control of the main spindle motor and the acceleration of the main spindle is continued and completed while processing this control parameter set.

The exemplary run-up curve K3 has an acceleration section K31 between the times t2 and t4, which is longer than the acceleration section K11 or K21 of the run-up curve K1 or K2. The set of control parameters for a soft start allows a longer duration for the initial acceleration of the clamping and for overcoming the initial inertia and static friction. The acceleration of the main spindle runs in comparison to the acceleration section K11 or K21 of the run-up curve K1 or K2. with lower dynamics and has a lower gradient in the acceleration of the main spindle.

A linear section K32 follows between the times t4 and t5. Compared to the linear section K12 or K22 of the run-up curve K1 or K2, the linear section K32 of the exemplary run-up curve K3 has a shorter duration and a steeper slope. According to an advantageous further embodiment of the invention, such a course can be achieved, for example, by motor control with a controller which has at least one P component and one I component. A set of control parameters for a soft run-up can then be equipped with an increased amplification factor and an increased reset time compared to a set of control parameters for a normal run-up. Due to the increased reset time, a reduction in the drive dynamics adapted to the respective clamping can be achieved in the acceleration and braking periods, ie between t1 and t4 or t5 and t7. The longer periods of time that occur for gentler changes in acceleration, ie with lower gradients in the acceleration of the main spindle, can be compensated for by an increased amplification factor, so that the linear section K32 is shortened due to a greater acceleration. Thus, even when processing a set of control parameters for a soft run-up _{, the setpoint speed U desired of the main spindle desired by an operator is} approximately reached within the original run-up time t _h .

The third ramp-up curve K3 has a deceleration or braking section K33 between times t5 and t7. This also has a longer duration than the deceleration section K13 or K23 of the run-up curve K1 or K2. The set of control parameters for a soft run-up thus enables a longer period of time for the deceleration of the clamping shortly before the setpoint speed U setpoint _is reached. The main spindle is therefore braked more slowly and with less dynamics than in the deceleration section K13 or K23 of the run-up curve K1 or K2. Due to the longer duration and lower dynamics of the deceleration, there is a post-oscillation of the speed U of the main spindle within the acceptable tolerance range Ut in the post-oscillation section K34. The upper and lower tolerance speeds U _tu and Uto are not exceeded. Here, too, the machining of a workpiece can begin at point in time t7 at the end of run-up time t _h .

Reference List

D

Conventional lathe

D1

machine frame

D11

main spindle motor

D12

engine control

D13

tachometer

D14

Transmission device, in particular belt drive

D2

headstock

D21

main spindle

D22

clamping devices

D3

machine bed

D31

pull spindle

D32

lead screw

D4

bed slide

D41

cross slide

D42

Tool

D43

castle nut

D5

machine control

D51

Data Connection

pm

Set of control parameters for a normal run-up with normal clamping

PS1

Control parameter set for a soft start with increased clamping

PS2

Control parameter set for a soft start with high clamping

PS3

Control parameter set for a soft start with very high clamping

umom

Current speed of the main spindle motor

Imom

Instantaneous motor current of the main spindle motor

mmm

Instantaneous torque of the main spindle motor ins. immediately after activation

MS1

Threshold for control parameter set P _S1

MS2

Threshold for control parameter set P _S2

MS3

Threshold for control parameter set P _S3

L1

Torque-time curve with normal clamping: P _N

L2

Torque-time curve with increased clamping: P _N → P _S1

L3

Torque-time curve at high clamping: P _N → P _S2

L4

Torque-time curve with very high clamping: P _N → P _S3

MN

Breakaway torque of the main spindle motor with normal clamping

U1

Exceeding of the threshold M _S1 by instantaneous torque at L1

U21

Exceeding of the threshold M _S1 by instantaneous torque at L2

U22

Exceeding of the threshold value M _S2 by instantaneous torque at L2

U31

Exceeding of the threshold M _S1 by instantaneous torque at L3

U32

Exceeding of the threshold M _S2 by instantaneous torque at L3

U33

Exceeding of the threshold M _S3 by instantaneous torque at L3

t

timeline

t1

Time of activation of the main spindle motor

tm

Time span after activation, measurement period

t2, t3, t4, t5, t6, t7

Points in time on the time axis in 4

th

Run-up time of the main spindle

tn

Post-oscillation time of the speed of the main spindle

u

Speed actual value of the main spindle

usol

Target speed of the main spindle, adjustable

Ut

Tolerance range of the target speed of the main spindle

Uto

upper tolerance speed

utu

lower tolerance speed

K1

Ramp-up curve of the main spindle with control parameter set for normal acceleration and clamping with a normal mass moment of inertia

K11

acceleration section

K12

linear section

K13

Braking section, deceleration section

K14

ringing section

K2

Ramp-up curve of the main spindle with control parameter set for normal acceleration and clamping with an increased mass moment of inertia

K21

acceleration section

K22

linear section

K23

Braking section, deceleration section

K24

ringing section

K3

Ramp-up curve of the main spindle with control parameter set for gentle acceleration and clamping with increased mass moment of inertia

K31

acceleration section

K32

linear section

K33

Braking section, deceleration section

K34

ringing section

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 202019104050 U1 [0002]

Claims (12)

Conventional lathe (D) with a main spindle (D21), which is driven by a main spindle motor (D11) with a motor control (D12), and with a machine control (D5) in which at least one set of control parameters for the motor control (D12) is stored a normal run-up (P _N ) of the main spindle (D21) with a clamping that has a normal mass moment of inertia on average, - at least one control parameter set of the motor control (D12) for a soft run-up (P _S1 , P _S2 , P _S3 ) with reduced drive dynamics of the main spindle (D21) with a clamping that has at least an increased mass moment of inertia on average, - a period of time (t _m ) after the activation (t=0) of the main spindle motor (D11), and - at least one threshold value ( _{MS1, MS2 ,} M _S3 ) for the instantaneous torque (M _mom ) of the main spindle motor (D11), which is assigned to a set of control parameters for a soft start ( _PS1 , _PS2 , _PS3 ) of the main spindle (D21), the machine control ung (D5) is designed in such a way that this - upon activation (t=0) of the main spindle motor (D11) of the motor control (D12) provides the set of control parameters for the normal run-up (P _N ), - in the time period (t _m ) the instantaneous - Torque (M _mom ) is monitored, and - the motor control (D12) of the main spindle motor D11) provides a control parameter set for a soft start (P _S1 , P _S2 , P _S3 ) for the further run-up instead of the set of control parameters for the normal run-up (P _N ). , if during the time period (t _m ) in the _{instantaneous} torque (M _mom ) an exceeding of the threshold value ( _MS1 , _MS2 , _MS3 ) assigned to a set of control parameters for a soft run-up (PS1, _PS2 , _PS3 ) was detected. Conventional lathe after claim 1 , wherein the motor control (D12) exerts reduced drive dynamics in a control parameter set for a soft run-up (P _S1 , P _S2 , P _S3 ) on the main spindle motor with a lower gradient than in the control parameter set for a normal run-up (P _N ). Conventional lathe according to one of claim 1 or 2 , whereby in the machine control (D5) for exerting a reduced drive dynamics on the main spindle (D21) are stored - in each case a set of control parameters for a soft run-up (P _S1 , P _S2 , P _S3 ), which is assigned to a clamping on the main spindle, the one on average has an increased, high or very high mass moment of inertia, and - a threshold value ( _MS1 , _MS2 , _MS3 ) _each , which is assigned to a set of control parameters for a soft run-up (PS1, _PS2 , _PS3 ), and its magnitude increases with the mass moment of inertia of the respective clamping. Conventional lathe after claim 3 , wherein the motor control (D12) to exercise a reduced drive dynamics with a set of control parameters for a soft start (P _S1 , P _S2 , P _S3 ) with the increase in the average mass moment of inertia of a clamping on the main spindle (D21) decreasing gradient in the acceleration on the Main spindle (D21) exerts. Conventional lathe after claim 4 , where a gradient in the acceleration of the main spindle (D21) depends on the ratio of the moment of inertia in a setup with a normal moment of inertia to the moment of inertia in a setup with an increased, high or very high moment of inertia. Conventional lathe according to one of the preceding claims, wherein the motor control (D5) - contains a controller which has at least a P and I component, and - a set of control parameters for a soft start (P _S1 , P _S2 , P _S3 ) compared to a set of control parameters for a normal run-up (P _N ) has an increased amplification factor and an increased reset time. Conventional lathe according to one of the preceding claims, wherein the period of time (t _m ) is selected such that it includes the time range of the breakaway phase of the main spindle (D21) after activation of the main spindle motor (D11). Conventional lathe after claim 7 , wherein the period of time (t _m ) comprises a period in the range of 200 to 800 milliseconds. Conventional turning machine according to one of the preceding claims, wherein the machine control (D5) shuts down the main spindle motor (D11) with the control parameter set (PN , P _S1 , _{P S2} , P _S3 ) active in the motor control (D12). Conventional lathe according to one of the preceding claims, wherein the machine control (D5) is designed such that in the thread cutting mode and activation of the main spindle motor (D11) after an interim standstill, the main spindle (D21) is started up without monitoring the instantaneous torque (M _mom ) with the in the Motor control (D12) each active control parameter set takes place (P _N , P _S1 , P _S2 , P _S3 ). Conventional lathe according to one of the preceding claims at least with a feed spindle (D31) for driving the bed carriage (D4). Conventional lathe after claim 11 , at least with a lead screw (D32) for driving a bed slide (D4) in the thread cutting mode, and with a lock nut (D43), which is in the thread cutting mode with the lead screw (D32) engaged, the machine control (D5) is designed in such a way that in the thread cutting operating mode a standstill of the main spindle (D21) and a disengagement of the lock nut are detected and the main spindle motor (D11) restarts after renewed activation by the motor control (D12) with the control parameter set for normal run-up (P _N ). is approached.

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