DE102016125749A1 - Monitoring method and monitoring device for a numerically controlled machine tool - Google Patents

Abstract

The invention relates to a monitoring method for a numerically controlled machine tool, in particular a Fräsdrehmaschine (1) with at least one rotatory workpiece drive and a separating protective device (6), according to the invention an actual geometry of a workpiece (2) and / or an actual mass distribution of the workpiece (2) is determined and compared with a predetermined reference value of a permissible geometry and / or a permissible mass distribution. According to the invention, the monitoring device has at least one means for measuring the mass of a workpiece (2) clamped on a workpiece table (4) and / or at least one sensor (5) for detecting the workpiece geometry. ( 1 )

Description

The invention relates to a monitoring method and a monitoring device for a numerically controlled machine tool according to the preamble of the first and ninth patent claim.

The machine tools in this case have axle configurations which contain at least one workpiece rotation drive axes and have a separating protective device between the working space and the space where the operator is located. Known numerically controlled machine tools are equipped with guards to protect the operator from hazards that arise due to process-related, by improper operation and preparation of the machine or from stochastic errors such as material failure. These include, among other things, flying workpieces, tools or fragments. However, the separating guards have only limited strength, especially if they must be designed to be movable. These are designed and executed with regard to the mentioned hazards. With instructive instructions in the operating instructions of the machines, the danger to the operator is additionally reduced. However, the instruction is difficult in the event that different parameters are not immediately apparent to the operator or are not available at all. The mass of a workpiece is a common characteristic and can be limited both instructively and control technology. For lathes in addition, the moment of inertia of the workpiece is an adequate size, but it depends on how the mass is distributed and on which axis of rotation the value is related. For both types of machines (milling and lathes), their general structure gives rise to specific design methods for the guards. In addition, the maximum values of the parameters masses and moment of inertia can be limited in terms of drive and control technology and thus also the endangerment of the operator. But if the tasks of milling and turning are combined in a milling machine for milling, creating a new risk for this type of machine. The energetic state of a rotating, for example, on a Fräsdrehmaschine component can exceed that of a translationally moving workpiece only by a multiple and therefore requires the reinforced version of the separating protective device. It is assumed that the most unfavorable mass distribution of a released workpiece, which is possible in the given work space or the allowable workpiece size. Failure of the clamping device of the workpiece (released workpiece), in turn, the most diverse trajectories are possible, which lead to a collision with the protective device. The values for mass and moment of inertia also increase due to co-rotating clamping devices and other devices. Operators are thus subject to the risk of (subjective) assessment of the risk to be disregarded.

From the publication DE 199 45 395 A1 For example, a monitoring method and a monitoring device for machine tools with a motor-driven work spindle and a separating protective device are known. In this case, the actual mass moment of inertia of a tool used in the work spindle is determined on the basis of a measurement and compared with a calculated from predetermined tool data for this tool mass moment of inertia. In addition, a predetermined characteristic for the tool exchanged into the work spindle is compared with a maximum characteristic dependent on the strength of the protective device for this tool. The work spindle is only driven at a predetermined setpoint speed if the actual mass moment of inertia coincides with the calculated mass moment of inertia and the predefined characteristic is less than or equal to the maximum characteristic specified by the strength of the protective device.

The disadvantage of this solution is that it is not practical for use on Fräsdrehwerkstücke. The workpiece shapes and thus also the ratio between mass and moment of inertia can vary in this type of workpiece per machine in hardly manageable variety. On the other hand, the tools are part of the machine equipment. They are easily detectable. By contrast, the workpieces are usually customer property, through which only the most necessary information is known. For example, cavities of workpieces are often not dimensioned because they are not directly necessary for machining. On the other hand, they are absolutely essential for the determination of a mass moment of inertia.

The object of the invention is to increase the safety of the machine tool by reducing the risk to the machine operator is released by Fräsdrehwerkstücke released.

This object is achieved by a monitoring method according to claim 1 and a monitoring device according to claim 9 for a numerically controlled machine tool.

Advantageous embodiments emerge from the subclaims.

Advantageously, this is done for the first time an internal control and non-contact determination of the mass distribution and a dependent limitation of the motion parameters in the machine control and / or the inevitable use of additional mechanical reinforcement of the guards. With the solution according to the invention the risk is reduced by improper use of the machine.

According to the invention, for the first time, the actual values of the workpiece mass are set in relation to the different actual values of the moments of inertia and, based on models, conclusions about the mass distribution and geometry of the workpiece are drawn.

The basis of the monitoring procedure are the workpiece mass values identified by the machine control and the mass moment of inertia of the workpiece related to the respective axes of rotation. In this way, the process parameters, in particular the rotational speed of the axes of rotation of a machine tool can be limited workpiece-dependent. The risk of improper workpiece clamping is reduced in the way, since the knowledge of the mass distribution not only allows the parameter limitation but also instructive hints by the control of the machine.

The monitoring procedure is integrated into the control as a control function. For milling turning, both during manual machine operation and when working with an NC program, it must be carried out directly after the workpiece clamping with closed guards. After opening the protective door, the function must be carried out again.

The method is based on the model concept that Fräsdrehwerkstücke can be approximated to the shape of a cylinder, a hollow cylinder or other geometrically determined shapes. The composition of geometry from geometric basic forms is also possible. Alternatively, the method may be made more effective by integrating additional information. In addition to the image-sensory adjustment of the coarse workpiece shape and the use of other sensors such as acceleration sensors, the method can be designed so that the machine operator is asked to select a considered in a catalog forms.

• 1 eine 4-achs Fräsdrehmaschine,
• 2 eine 5-achs Fräsdrehmaschine.

The invention will be explained in more detail with reference to embodiments and accompanying drawings. Show it:

• 1 a 4-axis milling lathe,
• 2 a 5-axis milling lathe.

The procedure described below refers to a monitoring method for milling lathes gem. 1 and 2 ,

The kinematics of the milling lathe 1 according to 1 three linear drive axes with the Cartesian coordinates X, Y, Z and a rotary drive axis C (about the Z axis) on which that on a table 4 clamped workpiece 2 is turned. At the workpiece table 4 is a measuring device 3 arranged or integrated, with which the mass difference without workpiece and with clamped workpiece can be determined. Furthermore, within the machine is a sensor 5 arranged for determining / detecting the shape of the workpiece.

The working space is equipped with a protective device 6 umhaust consisting of fixed 6.1 and movable wall components 6.2 is constructed.

That on the workpiece table 4 recorded workpiece 2 is by means of a first linear drive 7.1 along the X-axis linearly adjustable horizontally and by means of a first rotary drive 8th rotatable about the rotational drive axis C. The workpiece 2 is doing by means of a workpiece clamping device 9 on the workpiece table 4 clamped.

The tool 10 is by means of the stand 11 by means of a second linear drive 7.2 along a horizontal second linear axis Y and by means of a main spindle unit 12 via a vertical third linear drive 7.3 adjustable along the Z axis. Outside the enclosure is a controller 13 intended.

The 5-axis machine according to 2 has three linear drive axes X, Y, Z and two rotary drive axes B and C, around which on a table 4 clamped workpiece 2 is pivotable and rotatable.

Again, is on the workpiece table 4 is a measuring device 3 arranged or integrated, with which the mass difference without workpiece 2 and with clamped workpiece 2 is determinable. Furthermore, there is also a sensor inside the machine 5 for determining / detecting the shape of the workpiece 2 arranged and the working space is equipped with a protective device 6 umhaust consisting of fixed 6.1 and movable wall components 6.2 is constructed.

In this variant, this is on the workpiece table 4 recorded workpiece 2 also by means of a first linear drive 7.1 along the X-axis linearly adjustable horizontally and by means of a second rotary drive 8.2 about the rotational drive axis C and by means of a first rotary drive 8.1 rotatable about the rotational drive axis B. The workpiece 2 is doing by means of a workpiece clamping device 9 on the work table pivotable about the drive axis B. 4 clamped.

The tool 10 is on a portal 11.1 by means of a second linear drive 7.2 along a horizontal second linear axis Y and by means of a main spindle unit 12 via a vertical third linear drive 7.3 adjustable along the Z axis.

The control 13 is like at 1 provided outside the housing.

1. (1) Für die unbeladene Fräsdrehmaschine 1 liegen die Werte für die bewegten translatorischen Massen m pro Antriebsachse X, Y, Z und die bewegten rotatorischen Massenträgheitsmomente J pro Dreh oder Schwenkachse B, C als Referenzwerte vor.
2. (2) Durch die Beladung der Maschine - hier eine Fräsdrehmaschine 1 - mit einem Werkstück 2 erhöhen sich diese translatorische Massewerte um die Masse des Werkstücks 2. Die Kontrollfunktion ermittelt im ersten Schritt die Differenz der Masse m mittels einer Überwachungseinrichtung. Diese kann aus einem Massesensor 3, der am Werkstücktisch 4 integriert ist, als auch eine steuerungsinterne Funktion (Parameteridentifikation) bestehen.
3. (3) Für diese steuerungsinterne Parameteridentifikation kann beispielsweise die translatorische Achse X verwendet werden, die zu einer Bewegung des Werkstücks 2 führt. Stehen für diese Funktion zwei Achsen zur Verfügung, ist eine Mittelung der Werte sinnvoll. Im nachfolgen Schritt werden für die vorhandenen werkstückseitigen Drehachsen - C in 1 sowie B und C in 2- die veränderten Massenträgheitsmomente J über eine Parameteridentifikation der zugehörigen rotatorischen Antriebe ermittelt.
4. (4) Überschreiten die identifizierten Kennwerte in den Schritten (1) und (2) nicht die ohnehin eingestellten antriebstechnischen Grenzwerte kann mit diesen Werten und den bekannten physikalischen Zusammenhängen für die Massenträgheitsmomente J auf die geometrische Form und damit auf die Masseverteilung geschlossen werden. Bei einer idealen Zylinderform des Werkstücks 2 ist allein mit den Werten m und J die vollständige Geometrie bestimmbar. Bei davon abweichenden Formen sind Annäherungen notwendig. Typische Masseverteilungen (Formen) von Fräsdrehteilen können tabellarisch und parametriert hinterlegt werden. Die Steuerungsfunktion prüft die Annahmen auf Übereinstimmung bzw. auch auf nicht zulässige Formen, die instruktiv bereits ausgeschlossen sind.
5. (5) Die Kontrollfunktion kann außerdem die Massenträgheitsmomente J verschiedener Achsen einbeziehen, wie es bei fünfachsigen Maschinenkonfigurationen mit zwei werkstückseitigen rotatorische Antriebsachsen möglich ist. Bei Kipp- oder Schwenkachsen erhöht sich das Massenträgheitsmoment durch den Steinerschen Anteil (m * R²), den die nicht auf der rotatorische Antriebsachsen liegende Werkstückmasse verursacht. D. h., beim Algorithmus wird zwischen vier- und fünfachsiger Fräsdrehmaschine unterschieden.
6. (6) Ermittelt das Verfahren mit der Kontrollfunktion eine unzulässige Masseverteilung, müssen weitere Schutzmaßnahmen ergriffen werden, wie z. B. die Verstärkung der trennenden Schutzeinrichtung durch Barrieren als flexible (variable) Schutzeinrichtungen. Ist auch das nicht möglich, kann die Bearbeitung des Werkstücks mit geschlossenen Schutztüren, d. h., mit vollem Leistungsumfang, nicht starten. Ist auch diese Bedingung nicht erfüllbar kann die Drehbearbeitung nur beginnen, wenn die maximal zulässigen Parameter wie die Drehzahl der Drehachsen in der Steuerung 13 gesenkt werden.

The following process steps are carried out successively:

1. (1) For the unloaded milling lathe 1 the values for the moving translatory masses m per drive axis X, Y, Z and the moving rotational mass moments of inertia J per rotation or pivot axis B, C are present as reference values.
2. (2) By loading the machine - here a milling lathe 1 - with a workpiece 2 these translational mass values increase by the mass of the workpiece 2 , The control function determines in the first step, the difference of the mass m by means of a monitoring device. This can be from a mass sensor 3 , the work table 4 is integrated, as well as an internal control function (parameter identification) exist.
3. (3) For this control-internal parameter identification, it is possible, for example, to use the translatory axis X, which results in a movement of the workpiece 2 leads. If two axes are available for this function, an averaging of the values makes sense. In the following step, for the existing workpiece-side axes of rotation - C in 1 as well as B and C in 2 - Determines the changed mass moment of inertia J via a parameter identification of the associated rotary drives.
4. (4) If the identified characteristic values exceed the steps ( 1 ) and ( 2 ) not the drive-related limit values set anyway can be concluded with these values and the known physical relationships for the mass moment of inertia J on the geometric shape and thus on the mass distribution. With an ideal cylindrical shape of the workpiece 2 the complete geometry can only be determined with the values m and J. For deviating forms approximations are necessary. Typical mass distributions (shapes) of milling turned parts can be stored in tabular form and parameterized. The control function checks the assumptions for correspondence or even for impermissible forms, which are already instructively excluded.
5. (5) The control function can also incorporate the mass moment of inertia J of various axes, as is possible with five-axis machine configurations with two workpiece-side rotary drive axes. For tilting or swiveling axes, the mass moment of inertia increases due to the Steiner proportion (m * R ² ) caused by the workpiece mass not lying on the rotary drive axes. That is, in the algorithm, a distinction is made between four- and five-axis milling lathe.
6. (6) If the procedure with the control function determines an inadmissible mass distribution, further protective measures must be taken, such as: B. Reinforcing the guard by barriers as flexible (variable) protection devices. If this is also not possible, machining of the workpiece with closed safety doors, ie with full performance, can not start. If this condition can not be met, turning can only begin if the maximum permissible parameters, such as the speed of the rotary axes in the control system, are not exceeded 13 be lowered.

umstellen ergibt: $$D^2=\frac{4\cdot m}{\pi \cdot h\cdot \rho }$$

Massenträgheit: $$J=D^2\frac{m}{8}$$

(1b) in (2): $$J=\frac{4\cdot m}{\pi \cdot h\cdot \rho }\frac{m}{8}=\frac{m^2}{2\cdot \pi \cdot h\cdot \rho }$$

For a cylinder, the following formula results, which allows to derive the diameter / height ratio from the mass m and the mass moment of inertia J about the (symmetry) axis of rotation: $$m={\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102016125749A1\_0012.png"\; state="\{\{state\}\}">D</figure-callout>}}^2\frac{\mathrm{<figure-callout\; id="4"\; label="\pi "\; filenames="DE102016125749A1\_0012.png,DE102016125749A1\_0013.png"\; state="\{\{state\}\}">\pi </figure-callout>}}{4}\cdot H\cdot \rho$$

change results in: $${\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102016125749A1\_0012.png"\; state="\{\{state\}\}">D</figure-callout>}}^2=\frac{4\cdot m}{\pi \cdot H\cdot \rho }$$

Inertia: $$J=D^2\frac{m}{\mathrm{8th}}$$

( 1b ) in ( 2 ): $$J=\frac{4\cdot m}{\pi \cdot H\cdot \rho }\frac{m}{\mathrm{8th}}=\frac{{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="DE102016125749A1\_0012.png"\; state="\{\{state\}\}">m</figure-callout>}}^2}{2\cdot \pi \cdot H\cdot \rho }$$

Diameter with "measured" values: $$D=\sqrt{\mathrm{8th}\cdot \frac{J}{m}}$$

For a hollow cylinder with the ratio V _dD from inner to outer diameter results:

Diameter ratio: $$d={\nu }_{dD}D$$

umstellen ergibt: $$D^2=\frac{4\cdot m}{\left(1-{\nu }_{\text{dD}}{}^2\right)\cdot \pi \cdot h\cdot \rho }$$

Massenträgheit: $$J=\frac{1}{4}\left(D^2+d^2\right)\frac{m}{2}=\frac{m}{8}\left(1+{\nu }_{\text{dD}}{}^2\right)\cdot D^2$$

(5b) in (6): $$J={\frac{m^2\left(1+{\nu }_{\text{dD}}{}^2\right)}{2\cdot \left(1-{\nu }_{\text{dD}}{}^2\right)\cdot \pi \cdot h\cdot \rho }}_{.}$$

Dimensions: $$m=\left(D^2-d^2\right)\cdot \frac{\mathrm{<figure-callout\; id="4"\; label="\pi "\; filenames="DE102016125749A1\_0012.png,DE102016125749A1\_0013.png"\; state="\{\{state\}\}">\pi </figure-callout>}}{4}\cdot H\cdot \rho =\left(1-{\nu }_{\text{dD}}{}^2\right)\cdot {\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102016125749A1\_0012.png"\; state="\{\{state\}\}">D</figure-callout>}}^2\frac{\mathrm{<figure-callout\; id="4"\; label="\pi "\; filenames="DE102016125749A1\_0012.png,DE102016125749A1\_0013.png"\; state="\{\{state\}\}">\pi </figure-callout>}}{4}\cdot H\cdot \rho$$

change results in: $${\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102016125749A1\_0012.png"\; state="\{\{state\}\}">D</figure-callout>}}^2=\frac{4\cdot m}{\left(1-{\nu }_{\text{dD}}{}^2\right)\cdot \pi \cdot H\cdot \rho }$$

Inertia: $$J=\frac{1}{4}\left({\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102016125749A1\_0012.png"\; state="\{\{state\}\}">D</figure-callout>}}^2+d^2\right)\frac{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="DE102016125749A1\_0012.png"\; state="\{\{state\}\}">m</figure-callout>}}{2}=\frac{m}{\mathrm{8th}}\left(1+{\nu }_{\text{dD}}{}^2\right)\cdot {\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102016125749A1\_0012.png"\; state="\{\{state\}\}">D</figure-callout>}}^2$$

( 5b ) in ( 6 ): $$J={\frac{m^2\left(1+{\nu }_{\text{dD}}{}^2\right)}{2\cdot \left(1-{\nu }_{\text{dD}}{}^2\right)\cdot \pi \cdot H\cdot \rho }}_{,}$$

With "measured" or identifiable values of m and J, we get: $$D=\sqrt{\frac{J}{m}\frac{\mathrm{8th}}{\left(1+{\nu }_{\text{dD}}{}^2\right)}}$$

About an image recognition 5 In addition, the workpiece shape of the on the table 4 clamped workpiece 3 recorded and the assignment to reference geometries are made. Thus both formulaic relationships and reference values can be used for the comparison. Exceeds the workpiece 3 in its dimensions a predetermined first dimension range, the protection device must be strengthened.

If the workpiece exceeds a predetermined second larger dimension range, the machining can not be started.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 19945395 A1 [0003]

Claims (9)

Monitoring method for a numerically controlled machine tool, in particular a Fräsdrehmaschine (1) with at least one workpiece side rotary drive axis and a separating protective device (6), characterized in that - an actual geometry of a workpiece (2) and / or an actual mass distribution of the workpiece (2) is determined and compared with a predetermined reference value of a permissible geometry and / or a permissible mass distribution and /. Monitoring procedure Claim 1 , characterized in that the actual mass distribution of the workpiece (2) on the basis of identified drive parameters of at least one drive axis of the workpiece and the actual mass contained therein and the moment of inertia of a workpiece table (4) with clamped workpiece (2) is determined. Monitoring procedure Claim 1 , characterized in that the actual mass distribution of the workpiece (2) by means of a sensor and the mass moment of inertia of a workpiece table (4) with clamped workpiece (2) is determined. Monitoring procedure according to one of Claims 1 to 3 , characterized in that the determination of the actual mass distribution of the workpiece (2) is model-based, - the determination of the actual mass distribution of the workpiece (2) based on the identified parameters of the workpiece side rotary drive axis of the Fräsdrehmaschine (1), the axis of rotation of the turning corresponds or with said axis and, if necessary, together a further existing pivot axis (B) of a carriage with workpiece (2), - the actual mass distribution is compared with a predetermined allowable mass distribution. Monitoring procedure according to one of Claims 1 to 4 , characterized in that - for the unloaded milling lathe (1) the values for the moving translatory masses per linear drive axis (7.1, 7.2, 7.3) of the workpiece are present as reference values, - for the unloaded milling lathe (1) the values for the moving rotational moments of inertia per rotational drive axis (8, 8.1, 8.2) of the workpiece are present as reference values, - that by loading the machine with a workpiece (2), these mass values change around the mass of the workpiece (2) and a control function in a first Step the difference of the mass by means of a mass sensor (3), which is integrated on the workpiece table (4) or by parameter identification of the linear drive axles, - in the following step, the changed moment of inertia of the existing workpiece side pivot or rotation axes (8) of the workpiece a parameter identification of the rotary drives is determined, - at If the identified characteristic values in steps (1) and (2) do not exceed the drive-related limit values set anyway, these values and the known physical relationships for the mass moment of inertia J can be used to deduce the geometric shape and thus the mass distribution. Monitoring procedure according to one of Claims 1 to 5 , characterized in that a workpiece shape of the workpiece (2) by at least one sensor (5) can be determined or is entered by manual input. Monitoring device for a numerically controlled machine tool, in particular a Fräsdrehmaschine with workpiece side rotary drive and separating protective device, characterized in that the monitoring device at least one means for measuring the mass of a workpiece on a table (4) clamped workpiece and / or at least one sensor (5) Has detection of the workpiece geometry. Monitoring device according to Claim 7 , characterized in that the means for measuring the mass is a mass sensor (3) and that the mass sensor (3) integrated in the workpiece table (4) or arranged on the workpiece table (4) or that with the monitoring device, the drive characteristics detected and the mass can be determined by comparison of drive characteristics with and without a workpiece. Monitoring device according to Claim 7 or 8th , characterized in that the sensor for detecting the workpiece geometry within a protective device (6) is arranged.

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