Method for operating a numerically controlled manufacturing machine and corresponding numerical control device

Abstract

The invention relates to a method for operating a numerically controlled manufacturing machine (2, 4) having at least one component (12A, 12B) which is subjected to mechanical and / or electrical loads when manufacturing a workpiece (5). The loads are described by values ​​of acceleration and / or impact of the at least one component (12A, 12B), wherein the values ​​can vary within a permissible value range (LIMIT1) during normal operation. The permissible value range (LIMIT1) is determined by the construction and structure of the manufacturing machine. For manufacturing the workpiece (5), a protective operation for reducing the mechanical and / or electrical loads is activated in a manner triggered by at least one control signal (30, 32, 34, 36). In the protective operation, the values ​​of acceleration and / or impact of the at least one component (12A, 12B) can vary within a partial value range (LIMIT2), wherein the partial value range (LIMIT2) is limited compared to the permissible value range (LIMIT1).

Description

Technical Field

[0001] The invention relates to a method for operating a numerically controlled manufacturing machine having at least one component, which is subjected to mechanical and / or electrical loads when manufacturing a workpiece, the loads being described by values ​​of acceleration and / or impact of the at least one component, wherein the values ​​can vary within a permissible value range during normal operation, wherein the permissible value range is determined by the construction and structure of the manufacturing machine, wherein, for the manufacture of the workpiece, a protective operation for reducing the mechanical and / or electrical loads is activated by means of a triggering action of at least one control signal.

[0002] The invention also relates to a numerical control device for a manufacturing machine, which is suitable for carrying out a method for such operation. Background Art

[0003] CNC manufacturing machines, such as machine tools or industrial robots, are used to produce workpieces. When using manufacturing machines, it is also important how quickly the workpieces are produced. The shorter the time it takes to process the workpieces, the more efficient the production or manufacturing process. Optimization methods are provided to shorten the processing time.

[0004] Manufacturers of machine tools or industrial robots compete with each other with slogans such as "precision and speed in production", "who provides the fastest or most precise machine", etc. The more precisely and / or faster a machine tool or industrial robot can produce a workpiece, the more attractive the manufacturing machine is to the user. Accordingly, the moving parts of the manufacturing machine (the term "machine axis" is often used to identify the movement of a machine component in space) are constructed and designed for large mechanical loads, especially large dynamic loads. Here, the limits of material loads are challenged, which substantially affects the service life or at least the frequency of maintenance intervals. The load limits are derived from the different load types of the machine elements. In an axis mechanism made of steel, that is, for example, in a ball screw, the guide or roller seat or slide seat wears quickly during rapid and frequent movement processes, and therefore must be frequently maintained or replaced. Electrical components designed for increasingly faster and more frequent movement processes (braking and acceleration processes) and always designed to be as small as possible (due to procurement costs, waste heat and space requirements, etc.) reach their thermal limits. For example, electrical components include feed components, via which a complex of drives of a production machine is connected to the supply network, and motor modules, which can be used to control the drive motors of the production machine. Electrical components are even operated at their limits for a long time.

[0005] In principle, many production processes can be stopped and started at any time. However, there are also production processes in which the workpiece quality and / or the processing process, etc. will be affected if the production process is stopped or started arbitrarily. This is mainly related to the temperature characteristics of the manufacturing machine or the workpiece. A specific example is that, for example, when there is no cooling water flowing through the working space of the fully automatic milling machine, when the electrical components of the axis are powered off and there is no friction due to lack of movement, the material is deformed due to temperature. Although the metal will only deform or bend slightly, for example, only by a few millimeters, it will destroy or substantially change the geometry or accuracy of the axis. The processing accuracy may no longer meet the requirements of the workpiece due to the bending. Manufacturing machines can usually only comply with the specified processing accuracy when they are in a hot running state, that is, when they are always moving, when there is always cooling water flowing through the working space, etc. This machine tool runs at high speed for a few minutes or even hours when necessary at the start of production to reach its operating temperature and thus its processing accuracy. Only then will the workpiece be processed or manufactured. Or it is even more expensive to produce the workpiece with reduced accuracy until the desired workpiece quality and workpiece accuracy are reached. Workpieces produced with reduced accuracy are subsequently disposed of.

[0006] Even in a specific production technology or processing type, arbitrary production starts, arbitrary production ends or production interruptions are intolerable. An example of this is the milling of gears, in which multiple mutually coupled machine axes engage workpieces and tools with each other, so that the production cannot be stopped. Tools and workpieces can be damaged. Another example of a production technology that is incompatible with interruptions is laser processing, in which the tool is a laser beam, which must first be placed in a specific operating state for a long period of time so that the laser beam can be processed. The use of a tape laying machine or a fiber laying machine to manufacture, for example, large aircraft components with temperature-treated materials (tapes, etc.) and temperature-treated workpieces or workpiece molds also does not allow any arbitrary changes to the production process.

[0007] In manufacturing machines, there are currently operating states that are turned on or off. In the on state, the manufacturing machine runs up to the mechanically and / or electrically permissible load limits. If the manufacturing process or production allows, they are switched to the off state so that axis movements are no longer performed. However, protecting the machine by stopping would require a longer start-up phase, as described above. Since the position and speed of the movement are preset in typical motion instructions (NC subroutines, etc.), "slow travel" is usually excluded in specific processes or technologies. For example, reducing the speed by means of an override switch or by changes to the NC (numerical control) subroutine is usually not goal-oriented, because specific processes on the machine tool are associated with the processing speed. For example, there are specific cutting speeds for the material matching to be achieved (workpiece material and cutting material). If the cutting speed is not adhered to, production problems in the form of deteriorated surface quality or increased tool wear result.

[0008] EP 3 015 929 A1 discloses a method for operating a machine tool, in which components of the machine tool can be activated and deactivated as required based on external control signals. User inputs and timer signals are referred to as external signals. The goal of EP 3 015 929 A1 is to keep components of the machine tool within a specific temperature range.

[0009] A method for operating a machine tool is known from GB 2 532 096 A, in which the expected energy requirement of the machine tool is determined based on expected operating parameters. If the expected energy requirement exceeds a preset upper limit, the operating parameters of the machine tool are changed by a higher-level control device to reduce the expected energy requirement to below the preset upper limit.

[0010] A method for operating a drilling machine is known from FR 2 978 932 A, in which the temperature occurring in the drill head and / or the drilling force required for drilling are detected and the rotational speed and feed rate of the drill head are set accordingly. The aim of the procedure of FR 2 978 932 A is to reduce wear.

[0011] From US 2018 / 0126509A1 a drilling machine is known in which the force acting on the drill bit by a drive is measured when the drill bit is embedded in and cuts the material of the workpiece to be drilled and when the drill bit is at a certain distance from the workpiece to be drilled. For a specific drill bit and workpiece material, the normal force when drilling is known. The drilling process is monitored to determine whether the measured force is normal, that is, whether it deviates from the expected value range, or whether abnormal forces occur. In the last case, the drilling process can be stopped and, if necessary, the rotation of the drill bit can be stopped.

[0012] US 2012093603 A1 discloses a machine tool for turning a workpiece, wherein when using a vibration detection unit, a stable vibration is detected in which no vibration occurs. To machine the workpiece, the speed is then adjusted to a speed suitable for machining and in which no vibration occurs. Summary of the invention

[0013] The invention is based on the object of providing a method for operating a numerically controlled manufacturing machine, by means of which the intervals for maintenance and / or replacement of machine parts can be extended while maintaining the manufacturing quality. The invention is also based on the object of providing a numerical control device designed to carry out the method.

[0014] The first-mentioned object is achieved by the method according to the invention. Accordingly, the method for operating a numerically controlled production facility as proposed in the introduction is characterized in that, in protective operation, the values ​​of the acceleration and / or the impact of at least one component can be varied within a partial value range, wherein the partial value range is restricted compared to the permissible value range.

[0015] The maximum permissible load is determined by the design and construction of at least one component, the permissible wear limit and / or its thermal load. Therefore, reducing this maximum permissible load in the protection operation means: reducing mechanical and / or thermal loads and thus reducing wear. The protection operation is activated in a specific manufacturing process depending on the utilization of the manufacturing machine. The manufacturing machine continues to operate in the protection operation. Therefore, there are no problems caused by stopping and restarting the operation. In particular, the temperature control of the working space remains largely constant and thus maintains the manufacturing accuracy. No warm-up phase is required. Depending on the scenario, the demand-oriented presetting of a limited partial value range of the load physical variable compared to the permissible value range can solve customer and application-specific problems in the machine wear range. The service life of the machine can be extended by operating the machine permanently or only temporarily in the "comfort zone".

[0016] An advantageous embodiment of the method according to the invention is characterized in that the movement of at least one component takes place at least along an axis and the movement variable includes the axis acceleration. Since the axis acceleration can only be changed within a limited partial value range during the protection operation, the maximum value of the acceleration along the axis is reduced relative to the permitted specified axis acceleration. The axis whose acceleration has been reduced performs the speed change more slowly, thereby generating smaller mechanical loads in the electrical and mechanical devices and thus generating less wear. In this way, the large loads on the axis mechanical and electrical devices are reduced by the acceleration and braking process, so that the protection operation is achieved.

[0017] A particularly advantageous design of the method according to the invention is characterized in that the manufacture of the workpiece comprises at least one first manufacturing step, in which the component acts on the workpiece, the manufacture of the workpiece comprises at least one second manufacturing step, in which the component does not act on the workpiece, and in the protective operation in at least one first manufacturing step the values ​​of acceleration and / or impact of at least one component can vary within a permissible range, and in the protective operation in at least one second manufacturing step the values ​​of acceleration and / or impact of at least one component can vary only within a restricted partial value range.

[0018] This means that no changes are made to the technical or actual machining or manufacturing process, since all machining variables to be achieved, such as cutting speeds, remain constant. The manufacturing quality of the workpiece is not impaired in this way, only the time between the individual machining or manufacturing steps, i.e. the time required for at least one second manufacturing step, is extended. In the case of a machine tool, the maximum values ​​of acceleration and / or impact are thus reduced only when the machining element is not acting on the workpiece, for example.

[0019] Another advantageous embodiment of the method is provided by the invention, wherein at least one control signal is preset by manual input at the user interface of the numerically controlled manufacturing machine. For example, the machine operator informs the control device: to operate at night at only 50% of the maximum axis acceleration on all axes.

[0020] An advantageous embodiment of the method is provided by the invention. According to this, when a limiting temperature of at least one component of the production machine is exceeded, at least one control signal is triggered. For the protection mode, the temperature of the shaft, the motor module or the power supply to the motor module can be used as a criterion for reducing the maximum value of the acceleration of the corresponding shaft.

[0021] The second mentioned object is achieved by the numerical control device of the invention.Accordingly, a manufacturing machine is designed to carry out the claimed method. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above features, characteristics and advantages of the present invention as well as implementation modes and methods become clearer and easier to understand in the following description of the embodiments, which are described in detail in conjunction with the accompanying drawings. Herein, a schematic diagram is shown:

[0023] Figure 1 shows the basic structure of a machine tool with a machine tool control device, and

[0024] Figure 2 The functional diagram of a control device for activating the protection mode is shown. DETAILED DESCRIPTION

[0025] The exemplary embodiment of the invention described below relates to a numerically controlled manufacturing machine which is designed as a numerically controlled machine tool. With the aid of corresponding adaptations determined by manufacturing technology but not affecting the basic working mode, this description also applies to the design of the manufacturing machine as a production robot. Both embodiments of the manufacturing machine have in common that a numerically controlled relative movement occurs between the processing part of the manufacturing machine and the workpiece during the production or processing of the workpiece.

[0026] Figure 1 The schematic diagram in FIG. 1 shows a digital machine control 2, which interacts with a machine tool 4 for manufacturing or machining a workpiece 5. The machine tool 4 together with the connected and adapted machine control 2 forms a numerically controlled manufacturing machine. The user or operator accesses the machine control 2 via an input / output unit 6, which is also referred to as an NC control panel. In addition, a communication interface 8 is provided, which enables the numerically controlled machine tool 4 to be embedded in a computer network (COMP) 9, and this mode of operation is referred to as distributed numerical control (DNC).

[0027] The machine tool control device 2 is divided into three main functional areas. The first main functional area, the COM (communication) part 10, performs communication tasks with connected peripheral devices (such as communication interface 8 and other input and output modules, sensors, limit switches, etc.). In addition, the COM part 10 is used to communicate with the input / output unit 6. The COM part also provides a programming environment, which includes at least one program editor, but usually also includes simulation and test devices.

[0028] The main task of the machine tool 4 is the manufacture or production and processing of the workpiece 5, wherein relative movement occurs between the processing part 12 of the machine tool 4 and the workpiece 5. The processing part 12 usually includes a plurality of parts 12A, 12B, etc., which work independently of each other or also work in coordination. Movable parts also belong to the parts 12A, 12B. For the movable parts, the machine tool control device 2 generates target values ​​for the movement to be implemented along one or more axes or motion axes 14, and the target values ​​achieve surface modeling or surface shape that meets the production presets while taking into account the drive components in the machine tool 4. The second main function of the machine tool control device 2, namely, route control and interpolation, and then generating motion target values ​​for each motion axis 14 of the machine tool 4 is implemented in the NC core 16.

[0029] Finally, the third main function of the machine control 2 is implemented by the adaptation control 18, which is used to adapt the general motion control related to the workpiece 5 from the NC core 16 to the specific machine tool 4. This includes the control of actuators via the input / output terminals 20 of the machine tool 4, the detection of sensor signals, the implementation of monitoring functions, the ensuring of safety functions, etc. The adaptation control 18 is implemented by means of a PLC (programmable logic controller), that is, a programmable logic controller.

[0030] The data or signal connection between machine tool control 2 and machine tool 4 is realized via first control lines 22 for movement target values ​​of axes 14 of machine tool 4 and via second control lines 24 for actuators and sensors in machine tool 4 .

[0031] The machine tool 4 is specified and constructed and designed accordingly for its specific use purpose and for different operating states. The design and construction of the components of the machine tool 4 are determined in particular by the mechanical load of the operation and in particular by the dynamic load allowed. This includes the maximum speed of the spindle, the maximum axis speed of the linear feed along the axis 14, the maximum acceleration along the axis 14 and the maximum impact on the axis 14. This also applies to impacts. The maximum value of the motion variable is applicable to the normal operation of the machine tool 4, that is, the use and operation of the machine tool 4 that meets the specifications. In normal operation, the value of the motion variable is always within the allowable value range LIMIT1, which is limited by negative and positive maximum values ​​allowed. The value can be the same size for all axes 14, but it can also be different. The value can be additionally determined by a specific state inside and / or outside the machine tool 4, for example, by the ambient temperature.

[0032] The permissible value range LIMIT1 belongs to the machine specifications. This value range is communicated to the control device 2 when the numerical control device 2 is put into operation together with the machine tool 4, for example via a setting file of the machine tool manufacturer and / or via the second control line 24. In addition, other possibilities for presetting the permissible value range LIMIT1 can also be provided via input masks and input dialogs. In this way, the numerical control device 2 can be parameterized for the connected machine tool 4 by setting the system variables provided for this purpose with respect to the machine tool 4.

[0033] In addition to the normal operation described above, the machine tool 4 can operate in a protection operation with the permissible value range LIMIT1. In the protection operation, a partial value range LIMIT2 is activated, which is limited compared to the permissible value range LIMIT1. The limitation can be realized by means of a reduction factor, but more complex reduction algorithms or reduction tables or reduction characteristic curves that take into account the interrelationships of the physical variables can also be used. The protection operation can in principle be preset individually for each movement axis 14 of the machine tool 4.

[0034] Figure 2 The activation of the protection operation is shown. For example, different possibilities for presetting the protection operation are shown. First, the machine tool operator can preset by means of a manual input 30 via the input / output unit 6 that the machine tool 4 should work in the protection operation. Optionally, the protection operation can be preset by means of a time control 32. For example, the machine tool 4 can be operated in normal operation during the day and in the protection operation at night. It is also possible that the protection operation is preset via a remote control 34. For example, in the case of a reduction in manufacturing orders for a certain time period, the manufacturing manager can manufacture a reduced number of workpieces 5 in the protection operation and inform the machine tool 4 of this via the computer network 9. It is also possible to activate the protection operation via the status of the components in the machine tool 4. Via a corresponding limit value message 36, for example exceeding the permitted motor or power electronics temperature, the control device 2 is switched to the protection operation.

[0035] Whether the machine tool 4 is to be operated in normal operation or in protection operation depends on a corresponding control signal at one of the possible input points 30, 32, 34, 36. This is illustrated by means of program branch 38. If there is no requirement for the machine tool 4 to be operated in protection operation, i.e. Figure 2 If the output of the program branch 38 is "N", the permissible value range LIMIT1 is adopted for all physical load variables. The value of the physical variable can adopt any value within the permissible value range LIMIT1. The value is determined by the specifications of the machine tool 4. Normal operation is described by the first branch 40.

[0036] If there is a need for protection operation, that is, Figure 2 If the output of program branch 38 is "Y", then the partial value range LIMIT2 is used at least for one production step. This reduces the mechanical and / or electrical load in the production step compared to normal operation.

[0037] When the protection operation is first executed, the partial value range LIMIT2 is used both for the first production step 46 in which the machining component 12 or one of its components 12A, 12B, etc. acts on the workpiece 5 and for the second production step 48 in which the machining component 12 or one of its components does not act on the workpiece 5. Tool changes and movements between different processes that follow each other discontinuously also belong to the second production step, such as drilling a plurality of identical holes in succession. This first embodiment of the protection operation is illustrated by the second branch 42.

[0038] Depending on production technology and production quality requirements, a safety mode can also be activated only for the second production step 48 of the machine tool 4 , wherein the processing element 12 of the machine tool 4 does not act on the workpiece 5 ; this third embodiment of the safety mode is illustrated by the third branch 44 .

[0039] The mechanical loads on the moving parts are mainly caused by acceleration and braking processes. In a simple but nevertheless very effective embodiment of the protection operation, the maximum value of the acceleration and / or impact is reduced for all moving axes 14, i.e. the limit of the partial value range LIMIT2 is reduced, for example to half of the maximum value in normal operation, i.e. half of the limit of the permissible value range LIMIT1.

[0040] The possibility of presetting the second maximum value can be realized by means of a command in the control program, by means of which an input is requested from the machine controller. By means of the input request, the machine controller is given the possibility to activate the restricted partial value range LIMIT2. This gives the user access to variables, parameters and permissible value ranges which were preset by the manufacturing machine as the permissible value range LIMIT1 when the control device was initialized together with the manufacturing machine.

[0041] Similar to the parameterization at the start of the machine control device 2, one or more embodiments of the protection operation can be stored as a protection operation module in the machine control device 2. The protection operation module can be designed so that the partial value range LIMIT2 can be preset or changed interactively at the input / output unit 6 by the machine controller.

Claims

1. A method for operating a numerically controlled manufacturing machine having at least one component (12A, 12B), said component (12A, 12B) being subjected to mechanical and / or electrical loads during the production of a workpiece (5), said loads being described by values ​​of acceleration and / or impact of at least one of said components (12A, 12B), wherein: The value can vary within a permissible value range (LIMIT1) during normal operation, wherein the permissible value range (LIMIT1) is determined by the design and construction of the production machine, wherein a protective operation for reducing the mechanical and / or electrical load is activated in order to produce the workpiece (5) by means of at least one control signal, The invention is characterized in that, during the protection operation, the value of the acceleration and / or impact of at least one of the components (12A, 12B) can vary within a partial value range (LIMIT2), wherein the partial value range (LIMIT2) is limited compared to the permissible value range (LIMIT1), the manufacture of the workpiece comprises at least one first manufacturing step (46), in which at least one of the components (12A, 12B) acts on the workpiece (5), and the manufacture of the workpiece (5) comprises at least one second manufacturing step (48), in which In the second manufacturing step (48), at least one of the components (12A, 12B) does not act on the workpiece (5), in the protection operation, the acceleration and / or impact value of at least one of the components (12A, 12B) in at least one of the first manufacturing steps (46) can vary within the permissible value range (LIMIT1), and in the protection operation, the acceleration and / or impact value of at least one of the components (12A, 12B) in at least one of the second manufacturing steps (48) can only vary within the limited partial value range (LIMIT2).

2. The method according to claim 1, characterized in that The movement of at least one of the components (12A, 12B) is at least along an axis (14) and the movement variable includes an axis acceleration.

3. The method according to claim 1 or 2, characterized in that: At least one of the control signals is preset by manual input at an input / output unit (6) of the numerically controlled manufacturing machine.

4. The method according to claim 1 or 2, characterized in that: At least one of the control signals is triggered by a state of at least one of the components (12A, 12B) of the manufacturing machine.

5. The method according to claim 1 or 2, characterized in that: In the event that a limiting temperature of at least one of the components (12A, 12B) of the manufacturing machine is exceeded, at least one of the control signals is triggered.

6. The method according to claim 1 or 2, characterized in that: At least one of the control signals is triggered in a remote control manner.

7. The method according to claim 1 or 2, characterized in that: At least one of the control signals is triggered in a time-controlled manner.

8. The method according to claim 1 or 2, characterized in that: The manufacturing machine is embedded in a computer network (9), and at least one of the control signals is preset by a control computer connected to the computer network (9).

9. The method according to claim 1 or 2, characterized in that: The production machine is designed as a machine tool.

10. The method according to claim 1 or 2, characterized in that: The manufacturing machine is designed as a production robot.

11. A numerical control device for a manufacturing machine, the numerical control device being designed to carry out the method according to any one of claims 1 to 10.

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