Turning apparatus comprising an adaptive process control system
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SCHAEFFLER TECHNOLOGIES AG & CO KG
- Filing Date
- 2025-11-20
- Publication Date
- 2026-06-25
AI Technical Summary
Existing hard turning processes lack flexibility and efficiency due to fixed cutting parameters, leading to increased tool wear, variations in workpiece quality, and higher costs, with a need for improved process reliability and cost-effectiveness.
A rotary device with adaptive process control that adjusts cutting speed and feed rate based on real-time process data, including material properties, roughness, and active power, to ensure consistent surface quality and extend tool life.
The adaptive control system enhances process reliability, reduces machining time, minimizes tool changes, and ensures high-quality workpiece surfaces while being cost-effective and environmentally friendly.
Smart Images
Figure DE2025101089_25062026_PF_FP_ABST
Abstract
Description
[0001] P241352 - 1 -
[0002] Rotary device with adaptive process control
[0003] The following descriptions concern a rotary device for hard turning a workpiece with adaptive process control, which improves tool life and workpiece surface quality. Furthermore, the following descriptions concern a method for operating the rotary device.
[0004] It is known that hard turning is usually performed with constant cutting parameters such as cutting speed and feed rate, which cannot be adjusted to the tool's wear condition or the surface finish. This leads to increased tool wear and quality variations. Established processes lack integration of material properties, process forces, and power, resulting in inefficient and inflexible processes. Higher cutting speeds and dynamic adjustments are avoided due to a lack of process reliability, leading to longer machining times and higher costs.
[0005] There is a constant need to enable the manufacturing process of a rotary device in a cost-effective manner while maintaining process reliability and the required surface quality of the workpiece.
[0006] Based on this situation, the task at hand is to identify measures that can make the manufacturing process of a rotary device more cost-efficient and increase process reliability.
[0007] The present problem is solved by the features of the independent main claim. Advantageous embodiments are specified in the dependent claims. Where technically feasible, the teachings of the dependent claims can be combined arbitrarily with the teachings of the main and dependent claims. P241352 - 2 -
[0008] The task is therefore solved by a rotary device for hard turning a workpiece, comprising:
[0009] - a spindle for rotating and clamping the workpiece on the rotary device;
[0010] - a tool that can be moved relative to the clamped workpiece for removing material from the workpiece surface by machining;
[0011] - an adaptive process control for receiving and evaluating process data and for setting operating parameters; wherein the process data includes the material properties of the workpiece and / or the material properties of the tool and / or a roughness R generated by the tool on the workpiece surface z and / or control data of the rotary device, wherein the adjustable operating parameters include at least the cutting speed v c of the workpiece and the feed Vf of the tool; wherein the workpiece is moved via the spindle at an initial cutting speed v c is rotatable about a rotational axis, wherein the tool can be moved at least partially parallel and / or orthogonal to the rotational axis by means of an initial feed Vf, wherein at least one operating parameter, in particular the cutting speed v cand / or the feed rate Vf is adaptively adjustable depending on the received process data by means of the process control.
[0012] By adaptively adjusting the operating parameters, compliance with the maximum permissible roughness R can be ensured. z The surface of the workpiece is protected across the entire machining path. At the same time, the tool life can be increased and / or the cycle time of the turning process reduced. This also reduces the energy input in the workpiece's edge zone.
[0013] The present turning device offers numerous advantages that improve both the efficiency and the quality and cost-effectiveness of the hard turning process.
[0014] Through adaptive control of cutting speed and feed rate, based on real-time data, in particular the wear mark width VB or the roughness R zThis enables precise process adjustment. As a result, P241352-3 significantly extends tool life, since wear conditions are detected early and countermeasures are automatically initiated. This reduces the number of tool changes, thereby saving costs and increasing machine availability.
[0015] Another crucial advantage is the consistent assurance of the workpiece's surface quality. Adherence to specified roughness values, particularly with regard to downstream processes such as honing, minimizes scrap and guarantees high-quality workpiece surfaces. Simultaneously, machining time is significantly reduced through optimized adjustment of operating parameters. In particular, increasing the cutting speed to at least 220 m / min contributes to shorter production cycles without compromising process reliability or workpiece quality.
[0016] Process reliability is further enhanced by comprehensively considering workpiece and tool materials as well as external factors such as active power and passive forces. This makes the machining process more robust against material variations and ensures stable results even under varying conditions. In addition, the integration of correction factors enables high flexibility, allowing for the easy machining of different workpiece types and geometries.
[0017] A key advantage of the rotary device lies in its automation. The acquisition of process data, such as roughness R, is particularly beneficial. zThis process can be automated by sensor units, reducing manual intervention and operator errors. The adaptive control system reacts to changes in real time and dynamically optimizes the parameters. This not only increases efficiency but also relieves the workload of the operating personnel and ensures a consistently high surface quality of the workpiece.
[0018] Furthermore, the rotary device can be integrated into existing manufacturing systems, enabling cost-effective retrofitting. This makes it particularly attractive for companies that want to benefit from modern process control technologies without major investments. Finally, P241352-4 contributes to more sustainable manufacturing through more efficient tooling use and reduced scrap, as fewer resources are consumed and waste is avoided.
[0019] The rotary device can increase efficiency, process reliability, environmental compatibility and quality while simultaneously reducing production costs.
[0020] The following sections explain advantageous aspects and subsequently describe preferred modified embodiments. Explanations, particularly regarding advantages and definitions of features, are essentially descriptive and preferred, but not limiting, examples. If an explanation is limiting, this will be explicitly stated.
[0021] It is preferred that the sequence of process steps can be varied, unless a specific sequence is technically required. However, the aforementioned sequence of process steps is particularly preferred.
[0022] The workpiece is typically shaped like a roller, cone, or similar form. Tool life in hard turning describes how long a cutting tool can be used effectively before it becomes unusable or needs to be replaced. Since hard turning primarily involves machining hardened steels, especially those with a hardness of 45 to 65 HRC, the tool is subjected to considerable stress. The tool material is a crucial factor influencing tool life. Cubic boron nitride (CBN) is most commonly used due to its extreme wear resistance and ability to withstand high temperatures. Ceramic cutting materials are also employed. Cutting speed and feed rate play a significant role in tool life. High cutting speeds generate more heat, which accelerates tool wear. A high feed rate results in greater forces that place additional stress on the cutting edge.
[0023] In hard turning, three essential forces are at work: cutting force, feed force, and passive force. These forces arise from the contact between the cutting tool and the workpiece and influence the machining process in various ways. The cutting force is the largest of the three forces and acts in the direction in which the tool removes material, i.e., in the cutting direction. It is directly responsible for material removal and determines the energy consumption of the process. The cutting force is highly dependent on the material properties, the operating parameters (such as cutting speed and feed rate), and the tool geometry. The feed force acts in the direction of the tool's feed, i.e., along the axis of movement in which the tool is moved relative to the workpiece. This force influences the stability of the tool and the workpiece, as well as the resulting dimensional accuracy.Excessive feed force can lead to tool or workpiece deformation. The passive force acts perpendicular to the machined surface, i.e., across the cutting direction. It presses the tool against the workpiece and can cause undesirable side effects such as vibrations and impaired surface finish. In hard turning, the passive force is particularly relevant due to the high hardness of the material. It influences the load on the machine, especially the tool holder and the spindle.
[0024] These forces are interdependent and influenced by material properties, cutting conditions, and tool design. Therefore, it is crucial for the turning device to detect and control these forces during hard turning to achieve high dimensional and geometric accuracy as well as a good surface finish.
[0025] Turning is one of the most important manufacturing processes in machining. In this process, chips are removed from a workpiece to create a desired shape. During turning, the workpiece rotates around its own axis, the axis of rotation, generating the cutting motion, while the tool follows the contour to be created on the workpiece and generates the feed motion. The corresponding turning device is a lathe. The achievable accuracies regarding dimensions, shapes, and surface roughness R zare, as with most machining processes, comparatively good. After turning, the workpiece is either ready for installation or must be machined in a subsequent manufacturing process (P241352 - 6). Turning is divided into numerous process variants. If the tool is moved parallel to the axis of rotation of the workpiece, as in the present application (cylindrical turning or longitudinal turning), cylindrical shapes are produced. If, on the other hand, the tool is moved perpendicular to the axis of rotation, flat shapes result (face turning). The surface quality of the workpiece is measured as roughness R. z measured. During turning, a trace from the tool tip is visible on the surface of the workpiece. The roughness R z The roughness (Rz) is lower and therefore better in turning operations the larger the tool's tip radius and the lower its feed rate. Roughness Rz stands for "average roughness depth" and is defined according to the DIN EN ISO 4287 standard.
[0026] Generally, machining is divided into two main components: the cutting motion, which removes the chip, and the feed motion, which ensures continuous chip removal. In turning, the cutting motion is the rotational movement of the workpiece. The feed motion is the movement of the tool, which can move parallel to the axis of rotation (longitudinal turning), perpendicular to it (transverse turning), or in a plane between these two directions. The peripheral speed of the workpiece at the machining point corresponds to the cutting speed and is expressed in meters per minute (m / min). In machining, only the relative movement between the workpiece and the tool is relevant.
[0027] The speed in the feed direction is called the feed rate. Alternatively, the feed rate represents an important kinematic quantity, the distance the tool travels per revolution in the feed direction, expressed in mm / revolution. The feed rate can be calculated from the rotational speed and the feed rate. The angle between the cutting direction and the feed motion is generally referred to as the feed direction angle. In turning, it is a constant 90°.
[0028] Hard turning is a type of hard machining that allows workpieces with a hardness exceeding 54 HRC to be machined. Superhard tools, such as those made of cubic boron nitride, make it possible to machine such hard workpieces by turning. Hard turning is also possible with silicon nitride cutting ceramics and coated carbide, although these tools wear out more quickly.
[0029] The workpieces can be machined directly in their hardened state. This eliminates both annealing and grinding, resulting in shorter cycle times. Furthermore, expensive grinding machines can be avoided by performing the machining on more economical lathes. Hard turning is also more economical because a larger volume of material can be removed per unit of time (higher material removal rate). Since the workpiece shape is controlled by the tool movement during hard turning, it is also more flexible than other machining processes where the workpiece shape is often partially contained within the tool. Due to the greater chip thickness, hard turning requires less energy and can be performed with little or no coolant, a process known as dry machining or minimum quantity lubrication.
[0030] In particular, it is intended that the feed rate during hard turning can reach values between 0.01 and 0.15 mm / revolution. It is also specifically intended that the cutting speed during hard turning can reach values between 120 and 230 m / min. These values are therefore all significantly lower than those of conventional turning.
[0031] The operating parameters include in particular the cutting speed v c in m / min, the feed rate Vf in mm / revolution and the depth of cut a p (also called feed rate). For a known workpiece diameter, the cutting speed v is calculated c from the rotational speed of the workpiece at the spindle. On CNC lathes, the cutting speed can be adjusted. c The necessary speed is calculated by the process control system. Furthermore, CNC process controls allow programs for similar workpieces to be created using variable and operating parameter programming.
[0032] During machining, the operating parameters result in a specific cutting force and temperature at the tool, power consumption, vibrations, acoustic emissions (noise), and chip shapes. After machining, these parameters manifest themselves on the workpiece as achieved dimensions and surface finishes, as well as tool wear and incurred costs. As with most machining processes, the most important operating parameters are the feed rate, depth of cut, and cutting speed.
[0033] Increasing the cutting speed increases the material removal rate. However, for a given cutting material, it is also the primary factor influencing tool wear. Generally, the higher the cutting speed, the greater the wear. At low speeds, built-up edge formation can occur. In this case, part of the chip adheres to the cutting edge, leading to increased wear and poor surface quality. Increasing the cutting speed also results in a slower decrease in cutting forces, a property utilized in high-speed turning. The achievable cutting speeds are usually higher the more wear-resistant the cutting material used.
[0034] Alternatively or additionally, it may be provided that the setting of the operating parameters, in particular the cutting speed v cand the feed rate Vf, based on the wear mark width VB, which can be determined using a variety of correction factors and / or active powers. In particular, it is provided that the determination of the wear mark width VB is carried out at least on the basis of the material properties of the workpiece and / or the tool using a respective correction factor KM for the material used, KG for the geometry of the respective body and / or Op for the machining process. In particular, it is provided that the determination of the wear mark width VB is carried out at least on the basis of at least one force that varies over time using the correction factor K. p and the active power P p for the passive force, correction factor K c and active power P c The cutting force and / or correction factor Kf and the effective power Pf for the feed force are calculated. In particular, it is intended that the wear mark width VB is determined using the formula... P241352 - 9 - can be determined.
[0035] Where t e and t s The integration limits are used to determine the VB. Adaptive process control allows for adjustment of the operating parameters, cutting speed v. c and feed rate Vf based on the wear mark width VB. The wear mark width VB is a measure of tool wear, expressed as the width of the wear surface. By considering VB, wear conditions can be precisely determined and operating parameters optimized. This extends tool life, reduces the number of tool changes, and minimizes scrap. Increasing the cutting speed v c This leads to an exponential increase in the wear mark width VB due to thermal effects, while increasing the feed rate Vf leads to a linear increase in the wear mark width VB due to mechanical stress. An optimal combination of vc Vf is crucial for minimizing tool wear and maximizing productivity. The wear mark width VB can be used, in particular, to determine the contact time At. The correction factors can be determined empirically or through simulation. The correction factors of the rotary device can be calibrated, in particular, by means of calibration runs (known performance when traversing a specific geometry) during commissioning.
[0036] The wear mark width (VB) can be calculated using correction factors (KM for material properties, KG for geometry, Op for machining processes) and active forces (Pp for passive force, Pc for cutting force, PF for feed force). These factors take into account specific influences such as material type, workpiece geometry, and machining conditions. Precise calculation of the VB enables flexible process control.
[0037] The wear mark width VB can be calculated in particular using a mathematical formula that defines the integration limits t. s (Start time) and t e (End time) as well as the active power are taken into account. This allows the exact determination of the energy input, which correlates directly with tool wear. The calculation offers high accuracy and enables the determination of wear behavior in real time. P241352 - 10 -
[0038] Alternatively or additionally, it may be provided that the setting of the operating parameters, in particular the cutting speed v c and the feed rate Vf, based on the contact time At.
[0039] In particular, it is intended that the process control is designed using the wear mark width VB and the cutting speed v. c to determine the contact time At.
[0040] In particular, it is intended that the contact time At will be calculated using the formula
[0041] VB At = — v c The contact time (At) is the duration that the tool is in contact with the workpiece. It is determined based on the wear mark width (VB) and the cutting speed (v). c calculated. By adjusting the machining parameters based on At, the energy input can be optimized and the machining quality increased. The contact time decreases with increased cutting speed v. c and / or higher feed rate Vf. While a short contact time is beneficial for efficiency, it must be weighed against the increased thermal and mechanical stress on the tool. Optimal coordination of cutting speed v c and feed rate Vf is crucial for tool life and machining quality in hard turning.
[0042] Alternatively or additionally, it may be provided that the setting of the operating parameters, in particular the cutting speed vc and the feed rate Vf, upon reaching a maximum permissible roughness R z This has been done.
[0043] In particular, it is provided that when the maximum permissible roughness Rz is reached, the cutting speed v c The feed rate Vf is increased and reduced.
[0044] The roughness R z Roughness describes the average surface roughness depth and is a criterion for surface quality. If a maximum roughness is reached, for example three pm, the process control adjusts the cutting speed v. c and the feed rate Vf to ensure continued high surface quality. Compliance with the roughness requirements prevents rejects and enables post-processing of the workpiece. In particular, it is intended that P241352 - 11 - the cutting speed v cand the feed rate Vf can be varied such that the time-filling volume Q of the rotary device remains essentially constant. The time-filling volume Q can be determined in particular using the formula
[0045] Q = a p ■ v c ■ v f be calculated. Where a p The cutting depth is represented. A constant time interval Q ensures consistent machining times and stable process control. In particular, it is stipulated that the maximum permissible roughness R z three pm. In particular, it is planned that the roughness R will be measured. z continuous or discontinuous.
[0046] Alternatively or additionally, it may be provided that the roughness R is measured. z and the transmission of roughness R zThe roughness (Rz) can be measured and transmitted to the process control system either manually by an operator of the rotary device and / or automatically via a sensor unit. Sensor units can be optical, tactile, or laser-based systems. Automated measurement reduces errors and increases efficiency. Manual measurement is cost-effective and can be performed as needed.
[0047] Alternatively or additionally, it can be provided that the process control is designed to regulate the cutting speed v c , in particular the initial cutting speed v c , during hard turning, to be set to at least 200 m / min, in particular at least 210 m / min, most preferably at least 220 m / min. Due to the higher cutting speeds v cShorter processing times and increased productivity can be achieved.
[0048] Alternatively or additionally, it may be provided that the control data of the rotary device includes at least one active power input. In particular, it is provided that the control data includes at least one active power input, especially at least one current input, at a respective drive and / or at a frequency converter and / or at an intermediate circuit of the rotary device. P241352 - 12 -
[0049] In particular, the system is designed to allow continuous or discontinuous acquisition of active power. The control data includes active power, current, and other relevant parameters measured at drives, frequency converters, or DC links. This data serves as the basis for adaptive process control. Continuous acquisition of this data enables precise and flexible control of the machining process.
[0050] A frequency converter with a DC link and downstream drives plays a central role in a rotary device used for hard turning workpieces. Its main task is to process and control the electrical energy so that the rotary motion of the device can be performed precisely, efficiently, and adapted to the requirements of the machining process. First, the frequency converter transforms the alternating current from the mains power supply into a direct current and stores it in the DC link. This DC link not only serves as an energy buffer but also stabilizes the power supply to ensure a consistent and reliable energy input. The frequency converter then converts the stored direct current into a new, controllable alternating current. The frequency and amplitude of this current can be precisely regulated.This precise control is crucial for accurately adjusting the speed and torque of the spindle and / or tool drives in the turning fixture to the specific requirements of hard turning. Especially when machining hard materials, a smooth and controlled rotation is essential, as even the slightest deviations can negatively impact machining quality. Furthermore, the use of a frequency converter allows the turning fixture to be flexibly adjusted to different workpieces and machining speeds. The frequency converter also enables the rotation direction to be changed as needed, as well as smooth acceleration and deceleration of the rotation.Overall, measuring the active power upstream of the frequency converter ensures that the rotary device operates efficiently, that the motion sequences are precisely controllable, and that consistently high machining quality is achieved during hard turning. Monitoring can be performed independently of the drives installed in the rotary device. P241352 - 13 -.
[0051] Monitoring the active power at the frequency converter, particularly the current, allows for important conclusions to be drawn about the surface quality of the machined workpiece. During hard turning, the current draw of the drives and its fluctuations indicate the load acting on the turning device and the tool. This load is significantly influenced by factors such as the cutting forces, the material properties, and the condition of the tool. A consistent current draw indicates stable machining conditions, which generally results in a high surface quality of the workpiece. Fluctuations or sudden spikes in the current curve, on the other hand, can indicate irregularities during the machining process. Such irregularities could be caused, for example, by a deterioration of the tool's condition or an incorrect cutting speed.Continuous monitoring of the current before the frequency converter, the DC link, and / or the various drives for the spindle and the tool allows for the early detection of anomalies. This enables the identification of potential problems before they negatively affect the surface quality of the workpiece. For example, increased current consumption could indicate that the tool is worn and needs to be replaced to ensure consistent quality. This type of monitoring and analysis makes the frequency converter an important component of quality control in the hard turning process. It not only contributes to process reliability but also allows for the adjustment of the workpiece's surface quality by controlling the cutting speed. c and to optimize the feed rate Vf and to minimize wear on the tool and machine.
[0052] The problem is further solved by a method for operating a rotary device, which can be designed and further developed as described above, comprising the following steps:
[0053] - Providing a workpiece and a tool for hard turning;
[0054] - Rotating the workpiece using an initial cutting speed v c around the axis of rotation; P241352 - 14 -
[0055] - Method of moving the tool at least partially parallel and / or orthogonal to the axis of rotation by means of an initial feed Vf;
[0056] - Providing a variety of process data from the rotary device;
[0057] - Evaluating the process data using process control;
[0058] - adaptive adjustment of operating parameters, in particular the cutting speed v c and / or the feed Vf, the rotary device by the process control.
[0059] The method describes the steps for adaptively adjusting operating parameters based on the provided process data, including roughness Rz, wear mark width VB, and contact time At. The method thus offers a complete solution for optimizing machining processes, increasing both efficiency and quality.
[0060] Alternatively or additionally, the procedure may include the following steps:
[0061] - Measurement of roughness R z the surface of the workpiece by the operator of the rotary device and / or automatically by means of the sensor unit; wherein the adaptive adjustment of the operating parameters, in particular the cutting speed v c and the feed rate Vf, upon reaching a maximum permissible roughness R z this is done, whereby in particular the cutting speed v c The feed rate Vf is increased and reduced.
[0062] Alternatively or additionally, the procedure may include the following steps:
[0063] - Determination of the wear mark width VB based on a variety of correction factors and / or active powers; whereby the adaptive adjustment of the operating parameters, in particular the cutting speed v c and the feed rate Vf, depending on the wear mark width VB.
[0064] Alternatively or additionally, the procedure may include the following steps: P241352 - 15 -
[0065] Determination of the contact time At based on the wear mark width VB and the cutting speed v c; where the adaptive setting of the operating parameters, in particular the cutting speed v c and the feed rate Vf, depending on the contact time At.
[0066] Preferably, the cutting speed v is provided for. cThe feed rate Vf is increased and reduced.
[0067] The contact time At can be determined based on the wear mark width VB and the cutting speed v. c to be calculated. An adjustment of the cutting speed v c The feed rate Vf is adjusted accordingly to ensure machining quality. This adjustment reduces tool wear and achieves consistent results regarding the surface quality of the workpiece.
[0068] Alternatively or additionally, the procedure may include the following steps:
[0069] Providing control data with at least one active power, in particular at least one current, to a respective drive and / or to a frequency converter and / or to an intermediate circuit of the rotary device, wherein the adaptive adjustment of the operating parameters, in particular the cutting speed v cand the feed rate Vf, depending on the at least one recorded active power.
[0070] A preferred technical solution is explained in more detail below with reference to the accompanying drawings and preferred embodiments. The term "figure" is abbreviated as "Fig." in the drawings.
[0071] The drawings show
[0072] Fig. 1 shows a functional principle of an adaptive process control of a rotary device;
[0073] Fig. 2 shows a schematic curve of the cutting speed v c and the feed Vf of the rotary device; and P241352 - 16 -
[0074] Fig. 3 shows a circuit diagram for a variety of drives of the rotary device.
[0075] The described embodiments are merely examples that can be modified and / or supplemented in various ways within the scope of the claims. Each feature described for a particular embodiment can be used independently or in combination with other features in any other embodiment. Each feature described for an embodiment of a particular claim category can also be used accordingly in an embodiment of a different claim category.
[0076] Fig. 1 shows a functional principle of an adaptive process control 10 of a rotary device, wherein the process control 10 is configured to receive and evaluate process data 12 and to set the operating parameters 14. Where process data 12 include the material properties of the workpiece and / or the material properties of the tool and / or a roughness R generated by the tool on the workpiece surface. z and / or control data of the rotary device. The adjustable operating parameters include at least the cutting speed v. c The workpiece and the tool feed rate Vf are included. The operating parameters 14, in particular the cutting speed v, are also included. c and / or the feed rate Vf, are adaptively adjustable by means of the process control 10 depending on the received process data 12. The operating parameters are set in particular on the basis of at least one correction factor KM, KG and / or Op and / or the roughness R.z and / or at least one correction factor K p , K c and / or Kf and / or the associated active power P p , P c and / or Pf. Based on the received process data, the wear mark width VB, the contact time At, and / or the time span volume Q can be determined and used to set the operating parameters. By adaptively adjusting the operating parameters 14, it can be ensured that a required surface quality of the workpiece is maintained and the tool life is extended.
[0077] Fig. 2 shows a schematic diagram of the cutting speed v. c and the
[0078] Feed rate Vf of the rotary device during the turning process. At the beginning, in a P241352 - 17 - first process phase I, the workpiece rotates with an initial cutting speed v. cabout a rotational axis of the rotary device, whereby the tool is moved at least partially parallel and / or orthogonal to the rotational axis by means of an initial feed Vf. The tool life L indicates how much distance a tool travels on the workpiece surface or how many machining units it produces before it wears out. The tool life L is given in meters and is a measure of the effectiveness and service life of a tool in relation to the machined distance. The transition from the first process phase I to the second process phase II occurs as soon as the roughness R z a maximum permissible roughness R of the workpiece surface z , in particular three pm, has been reached. The process control receives the roughness value R z and adjusts the cutting speed v c and adjust the feed rate Vf accordingly.
[0079] The cutting speed v is then cincreased and the feed rate Vf reduced, in particular the cutting speed v c and the feed rate Vf is set such that the machining time Q of the rotary device remains essentially constant. Upon reaching a predetermined tool length L, in this case 10000 m, the cutting speed v c The cutting speed is further increased and the feed rate Vf is reduced accordingly, so that the machining time Q of the turning device remains essentially constant. In this way, the maximum possible tool life and tool duration can be significantly improved. This enables a cost-effective manufacturing process and optimal surface quality of the workpiece for potential post-processing. The cutting speed v is set c and the feed rate Vf can alternatively be set based on the contact time At, whereby the cutting speed v is also affected in this case. cThe feed rate (Vf) is increased and reduced so that the contact time (At) remains essentially constant. In the fourth process phase (IV) and in each subsequent phase, the process is repeated until the tool needs to be replaced due to wear or the operating parameters can no longer be adjusted.
[0080] Fig. 3 shows a circuit diagram for a plurality of drives 16, 18, 20, 22 for driving the spindle and the tool of the rotary device with a frequency converter 24, a DC link 26, a first measuring point 28 upstream of the frequency converter 24, a second measuring point 30 upstream of the DC link 26, and a third measuring point 32 upstream of the drives 16, 18, 20, 22. The drives 16, 18, 20, 22 are supplied with AC voltage via a power source L1, L2, L3, which is converted into DC voltage by means of the frequency converter 24 and provided as AC voltage for driving the individual drives 16, 18, 20, 22 via the DC link 26. The drives 16 and 22 each drive one or more spindles of the rotary device, with the drives 18 and 20 being designed for the indirect driving of the tool along a z- and x-axis of the rotary device.By measuring the current A at at least one measuring point 28, 30, 32, the active power P can be calculated according to the formula P=UI.
[0081] Monitoring the active power at the frequency converter 24, particularly the current A, at the first measuring point 28 allows important conclusions to be drawn about the surface quality of the machined workpiece. During hard turning, the current consumption of the drives 16, 18, 20, and 22, and their fluctuations, indicate the load acting on the turning device and the tool. This load is significantly influenced by factors such as the cutting forces, the material properties, and the condition of the tool. A consistent current consumption indicates stable machining conditions, which generally results in a high surface quality of the workpiece.
[0082] Fluctuations or sudden spikes in the current profile, however, can indicate irregularities during the machining process. Continuous monitoring of the current A upstream of the frequency converter 24, the DC link 26, and / or the various drives 16, 18, 20, 22 for the spindle and the tool allows for the early detection of anomalies. This enables the identification of potential problems before they negatively affect the surface quality of the workpiece. For example, increased current consumption could indicate that the tool is worn and needs to be replaced to ensure consistent surface quality. This type of monitoring and analysis makes the frequency converter an important component of quality control in the hard turning process.It not only contributes to process reliability, but also makes it possible to adjust the surface quality of the workpiece by setting the P241352 - 19 -.
[0083] Cutting speed v c and to optimize the feed rate Vf and to minimize wear on the tool and machine.
[0084] P241352 - 20 -
[0085] List of reference signs
[0086] 10 Process control
[0087] 12 Process data
[0088] 14 operating parameters
[0089] 16 First drive (spindle)
[0090] 18 Second drive (x-axis tool)
[0091] 20 third drive (y-axis tool)
[0092] 22 fourth drive (spindle)
[0093] 24 frequency converters
[0094] 26 Intermediate circle
[0095] 28 first measuring point
[0096] 30 second measuring point
[0097] 32 third measuring point
[0098] L Stand length
[0099] I first process phase
[0100] 11 second process phase
[0101] III third process phase
[0102] IV Fourth Process Phase
Claims
P241352 - 21 - Claims 1. Turning device for hard turning a workpiece, comprising: - a spindle for rotating and clamping the workpiece on the rotary device; - a tool that can be moved relative to the clamped workpiece for removing material from the workpiece surface by machining; - an adaptive process control (10) for receiving and evaluating process data (12) and for setting operating parameters (14); wherein the process data (12) are the material properties of the workpiece and / or the material properties of the tool and / or a roughness R generated by the tool on the workpiece surface z and / or control data of the rotary device, wherein the adjustable operating parameters (14) include at least the cutting speed v c of the workpiece and the feed Vf of the tool; wherein the workpiece is moved via the spindle at an initial cutting speed vc is rotatable about a rotational axis, wherein the tool can be moved at least partially parallel and / or orthogonal to the rotational axis by means of an initial feed Vf, wherein at least one operating parameter (14), in particular the cutting speed v c and / or the feed rate Vf is adaptively adjustable depending on the received process data (12) by means of the process control (10).
2. Rotary device according to claim 1, wherein the setting of the operating parameters (14), in particular the cutting speed v c and the feed rate Vf, based on the wear mark width VB, which can be determined by means of a variety of correction factors and / or active powers, wherein in particular the determination of the wear mark width VB is based at least on the material properties of the workpiece and / or the tool by means of P241352 - 22 - of a respective correction factor KM for the material used, KG for the geometry of the respective body and / or Op for the machining process, whereby in particular the determination of the wear mark width VB is carried out at least on the basis of at least one force that varies over time using the correction factor K p and the active power P p for the passive force, correction factor K c and active power P c for the cutting force and / or correction factor Kf and effective power Pf for the feed force, whereby in particular the wear mark width VB is determined using the formula can be determined.
3. Rotary device according to claim 1 or 2, wherein the setting of the operating parameters (14), in particular the cutting speed v cand the feed rate Vf, based on the contact time At, wherein in particular the process control (10) is designed by means of the wear mark width VB and the cutting speed v c to determine the contact time At, in particular the contact time At using the formula VB At = — v c can be determined.
4. Rotary device according to one of the preceding claims, wherein the setting of the operating parameters (14), in particular the cutting speed v c and the feed rate Vf, upon reaching a maximum permissible roughness R z This occurs, with the cutting speed v increasing particularly when the maximum permissible roughness Rz is reached. c The feed rate Vf is increased and reduced, in particular the cutting speed v. c and the feed rate Vf can be varied in such a way that the time span Q of the rotary device remains essentially constant, in particular the maximum permissible roughness Rz three pm, with particular emphasis on the measurement of roughness R z continuous or discontinuous. P241352 - 23 - 5. Rotary device according to one of the preceding claims, wherein the control data of the rotary device comprise at least one active power, wherein in particular the control data comprise at least one active power, in particular at least one current, at a respective drive (16, 18, 20, 22) and / or at a frequency converter (24) and / or at an intermediate circuit (26) of the rotary device, wherein in particular the current of the active powers can be detected continuously or discontinuously.
6. A method for operating a rotary device according to any one of claims 1 to 5, comprising the following steps: - Providing a workpiece and a tool for hard turning; - Rotating the workpiece using an initial cutting speed v caround the axis of rotation; - Method of moving the tool at least partially parallel and / or orthogonal to the axis of rotation by means of an initial feed Vf; - Providing a variety of process data (12) of the rotary device; - Evaluating the process data (12) using process control; - adaptive adjustment of operating parameters (14), in particular the cutting speed v c and / or the feed Vf, the rotary device by the process control (10).
7. The method of claim 8, comprising the following steps: - Measurement of roughness R z the surface of the workpiece by the operator of the rotary device and / or automatically by means of the sensor unit; wherein the adaptive adjustment of the operating parameters (14), in particular the cutting speed v c and the feed rate Vf, upon reaching a maximum permissible roughness R zthis is done, whereby in particular the cutting speed v c The feed rate Vf is increased and reduced.
8. The method of claim 8 or 9, comprising the following steps: P241352 - 24 - - Determination of the wear mark width VB based on a variety of correction factors and / or active powers; wherein the adaptive adjustment of the operating parameters (14), in particular the cutting speed v c and the feed rate Vf, depending on the wear mark width VB.
9. A method according to claims 8 to 10, comprising the following steps: determining the contact time At based on the wear mark width VB and the cutting speed v c; wherein the adaptive setting of the operating parameters (14), in particular the cutting speed v c and the feed rate Vf, depending on the contact time At, whereby in particular the cutting speed v cThe feed rate Vf is increased and reduced.
10. Method according to claims 8 to 11, comprising the following steps: providing control data with at least one active power, in particular at least one current, to a respective drive (16, 18, 20, 22) and / or to a frequency converter (24) and / or to an intermediate circuit (26) of the rotary device, wherein the adaptive adjustment of the operating parameters (14), in particular the cutting speed v c and the feed rate Vf, depending on the at least one recorded active power.