MACHINING METHOD

Abstract

A machining method for machining workpieces preferably consisting at least in sections of wood, wood materials, plastic or the like on a machining device, wherein a vibration state of the machining device is detected during a machining process, a closed-loop or open-loop control towards a lower or preferably optimal vibration state of the machining device is performed while the machining process is continued.

Claims

1. Machining method for machining workpieces preferably consisting at least in sections of wood, wood materials, plastic or the like on a machining device, wherein a vibration state of the machining device is detected during a machining process, and a closed-loop or open-loop control towards a lower or preferably optimal vibration state of the machining device is performed while the machining process is continued.

2. Machining method according to claim 1, wherein the closed-loop or open-loop control towards a lower or preferably optimal vibration state of the machining device is performed by adjusting a machining speed of the machining process.

3. Machining method according to claim 1, wherein the vibration state of the machining device is detected by a force sensor and/or strain gauge and/or vibration sensor and/or laser sensor and/or acoustic sensor and/or structure-borne sound sensor and/or piezoelement, wherein the vibration sensor is preferably an acceleration sensor, velocity sensor or displacement sensor.

4. Machining method according to claim 1, wherein a connection between a machining speed of the machining process and the vibration state of the machining device is carried out by means of an initial measurement during idling.

5. Machining method according to claim 4, wherein the initial measurement during idling is a speed sweep at which occurring vibrations are detected at predetermined, varying speeds.

6. Machining method according to claim 1, wherein acquired data from the operation and/or from the initial measurement can be provided to a database or an IoT (Internet of Things) platform and, preferably, the closed-loop or open-loop control is adjusted by data of the database or the IoT platform.

7. Machining method according to claim 1, wherein the machining process is continued during the closed-loop or open-loop control in that the relative movement between the machining device and the workpiece is not interrupted.

8. Machining method according to claim 1, wherein the machining process is a milling process and/or a drilling process.

9. Machining method according to claim 1, wherein the machining method is performed on a plurality of machining devices which are controlled by closed-loop or open-loop control towards their own vibration state that is different from the others.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 shows a view of a machining device of a first embodiment of the present invention.

[0027] FIG. 2 shows a flow chart of a first embodiment of the present invention.

[0028] FIG. 3 shows an actual state and a target state of a vibration state of a first embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0029] In the following, preferred embodiments of the present invention will be described with reference to the enclosed drawings. The embodiments described below can be combined in full or in part to form further embodiments.

[0030] FIG. 1 shows a view of a machining device of a first embodiment of the present invention.

[0031] In particular, FIG. 1 shows a machining device 1 which can perform machining methods according to the invention on workpieces preferably consisting at least in sections of wood, wood materials, plastic or the like.

[0032] This is enabled in the machining device 1 by a milling head 10 that can perform machining processes, by means of rotating movements, on workpieces that preferably consist at least in sections of wood, wood materials, plastic or the like.

[0033] Furthermore, the machining device 1 has a sensor 11 that is configured to measure vibrations during a machining process. The exact position of the sensor 11 is particularly advantageous where a particular stretching/compression of the corresponding part of the machining device 1 takes place. This can be measured and/or simulated by means of modal analyses and/or determined by trial and error.

[0034] The sensor 11 forwards the acquired data to a control device that is not shown. The control device is able to analyze the collected data and to send a control signal to the milling head 10 on the basis thereof. Based on this control signal, the milling head 10 can then adjust its milling speed.

[0035] The control device of the preferred first embodiment shown here also comprises a communication module using which the collected data can be transferred to a database or an IoT (Internet of Things) platform. The communication module is preferably provided as a network module or WLAN module. Furthermore, the communication module can also receive data from the database or the IoT platform in order to thus adjust an existing control.

[0036] FIG. 2 shows a flow chart of a first embodiment of the present invention.

[0037] In the left-hand area, an initial measurement is shown. This initial measurement can be carried out periodically, e.g. daily or weekly, and can serve as a calibration. Furthermore, it may also be necessary to design a new closed-loop control, for example for the use of a new milling head, for which the initial measurement is also performed.

[0038] In the initial measurement, a sensor provides data during a speed sweep. Here, speeds are given to the milling head 10, for example, with increasing speed, and resulting vibrations of the sensor 11 are detected. Thus, a functional connection between speed and vibration intensity can be established.

[0039] The data acquired in this manner can be provided to the database or the IoT platform.

[0040] In the right-hand area, a measurement during operation is shown.

[0041] Here, the machining device 1 starts the machining at a predetermined rotational frequency in a predetermined rotational frequency range. The operation at this rotational frequency causes vibrations that are detected by the sensor 11. Based on the vibrations with a certain rotational frequency, the control device now adjusts the rotational frequency within the predefined rotational frequency range in order to thus minimize or at least reduce the vibrations.

[0042] This process is therefore a control loop in which an actual value is controlled towards a target value. For example, a PID controller composed of a proportional, an integral and a derivative controller can be used as a controller.

[0043] Other controllers are also conceivable, of course; it is generally preferred that individual control parameters can be further optimized during operation.

[0044] FIG. 3 shows a diagram with an actual state and a target state of a vibration state of a first embodiment of the present invention.

[0045] In both diagrams, the course of the vibration intensity of an increasing speed is plotted. This curve can be detected by means of a speed sweep in the context of an initial measurement as shown above, for example. One measure of the vibration intensity is the vibration amplitude, for example.

[0046] At an actual speed, which is shown in diagram I, comparatively high vibration intensities occur. By the closed-loop control according to the invention, control towards a target speed in diagram II can be achieved, which constitutes a local minimum. A rotational frequency range can be specified in which the machining process takes place. For milling processes in the (CNC) stationary operation on workpieces consisting at least in sections of wood, wood materials, plastic or the like, a rotational frequency of, e.g., 24000 rpm is considered optimal, wherein this can be varied, for example, in a rotational frequency range of 10000 rpm to 30000 rpm, preferably 20000 rpm to 28000 rpm and more preferably 22000 rpm to 25000 rpm. For milling processes in continuous operation on workpieces consisting at least in sections of wood, wood materials, plastic or the like, a rotational frequency of, e.g., 6000 rpm is considered optimal, wherein this can be varied, for example, in a rotational frequency range of 4000 rpm to 30000 rpm, preferably 5000 rpm to 12000 rpm and more preferably 5000 rpm to 7000 rpm. Within these ranges, an optimum can be identified by means of a speed sweep, which serves as the new target value.

[0047] A second embodiment of the present invention comprises a machining device carrying out a machining process of cutting and/or edgebanding. With both possible machining processes, vibrations may occur that are minimized by means of the present invention. Cutting can be performed by means of a cross-cut saw blade whose speed is varied, and when performing edgebanding, the rotation of a pressure roller and/or the movement of mechanical components of a gluing device can be varied.

[0048] In a third embodiment, which is not shown, the machining method has a plurality of machining devices, e.g. corresponding to the first or second embodiment. These different machining devices are controlled by open-loop or closed-loop control with different target rotational frequency ranges such that each machining device works in a rotational frequency occurring only once. This results in that increased excitation owing to positional couplings of the unbalances of the machining motors is prevented.

LIST OF REFERENCE NUMBERS

[0049] 1 Machining device [0050] 10 Milling head [0051] 11 Sensor