WO2008028876A1

WO2008028876A1 - Machine tool monitoring device

Info

Publication number: WO2008028876A1
Application number: PCT/EP2007/059143
Authority: WO
Inventors: Michael Mahler; Reiner Krapf; Heiko Braun; Alexander Werner Hees
Original assignee: Robert Bosch Gmbh
Priority date: 2006-09-04
Filing date: 2007-08-31
Publication date: 2008-03-13
Also published as: DE102007039571A1; EP2064483A1

Abstract

The invention relates to a machine tool monitoring device having a detection unit (24) for detecting an application situation (66, 80) in a machine tool (10). According to the invention, the detection unit (24) allows for determining position and/or speed.

Description

Machine tool monitoring device

State of the art

The invention relates to a machine tool monitoring device according to the preamble of claim 1.

A machine tool monitoring device for a circular saw is known. This has a sensor unit for generating and detecting an electromagnetic signal, which is arranged in the vicinity of a saw blade. An approach of a body part to the saw blade can be detected by monitoring the signal spectrum.

Advantages of the invention

The invention relates to a machine tool monitoring device with a detection unit for detecting an application situation in a machine tool.

It is proposed that the recognition unit enables a position and / or velocity determination. There- by a movement of an object in a monitored by the machine tool monitoring device monitoring area can be characterized advantageous. This can be a movement which indicates a potential danger to an operator of the machine tool, quickly detected. A "position determination" is to be understood as meaning, in particular, the determination of the position of an object monitored by the machine tool monitoring device relative to an active object of the machine tool, in particular relative to a tool, preferably in its driven state the determination of at least one movement feature from the group movement direction, instantaneous speed value and instantaneous acceleration value of an object moving relative to an active object of the machine tool can be understood.

In a preferred embodiment of the invention, it is proposed that the machine tool monitoring device has at least one ultra-wideband radar sensor. It can be achieved with a use of ultra-wideband signals high information density - and thus an effective monitoring. In this context, an "ultra-wideband radar sensor" should be understood as meaning, in particular, a radar sensor by means of which an ultra-wideband radar signal can be generated, transmitted, received and / or evaluated an electromagnetic signal to be understood, which has a useful frequency range with a center frequency in the frequency range of 1 GHz to 15 GHz and a frequency bandwidth of at least 500 MHz. In particular, the ultra-wideband radar sensor is part of the detection unit.

Furthermore, high safety can be achieved if the position and / or velocity determination is a determination of the position and / or velocity of human or animal tissue. In particular, this recognition of human or animal tissue by means of a spectral evaluation of a radar signal, in particular an ultra-wideband radar signal, since such a tissue has a high attenuation effect in a frequency range above 2 GHz, whereby a high discrimination can be achieved.

Furthermore, it is proposed that the recognition unit has a means which is provided to associate at least one security measure with a movement feature of a monitored object. As a result, when a critical movement of the monitored object is detected on the basis of a characteristic movement feature, safety measures can be taken in good time and contact between the object and an active object of the machine tool can be avoided. This characteristic movement feature may be a direction of movement directed, for example, at the active object, or exceeding a predetermined threshold value of the instantaneous speed of the object and / or the instantaneous acceleration of the object, possibly due to slippage of a body part of an operator Indicate workpiece. The implementation of the security measure is preferably carried out by means of an actuator unit, which is in operative connection with the detection unit.

In particular, it is proposed that at least one movement feature is associated with a safety shutdown of the machine tool. As a result, a particularly high level of security can be achieved. In particular, in this case, the safety shutdown may be a stopping of a drive unit for driving a tool of the machine tool.

Advantageously, the detection unit has a means which is intended to classify a movement feature of a monitored object. In this way, a particularly short reaction time can be achieved merely by determining a speed level, such as "fast", "medium speed", "slow", etc., and wherein a safety measure is assigned to a speed level the assignment of the parameter to a predefined interval can be understood.

A particularly effective detection can be achieved if the machine tool monitoring device, in particular the detection unit, has an antenna array. In this context, an "antenna array" is to be understood as meaning, in particular, a group of a plurality of mutually different antennas which are fed with a signal to be transmitted during operation by means of a common signal generation unit on. The accuracy of detection can be increased if the antenna array is designed as a phase-variable antenna array. In this context, a "phase-variable" antenna array should be understood as meaning, in particular, an antenna array which is assigned at least one phase shifting means which is provided for changing at least one relative phase position between two signals radiated by different antennas of the antenna array.

High flexibility in the design of monitoring functions can be achieved if the recognition unit defines at least two monitoring areas for monitoring an application process of the machine tool. The monitoring areas are preferably designed differently from one another. Here, the monitoring areas may be formed separately or they may be adjacent to each other or they may form a common overlap area. In particular, a first overlapping area may comprise a second monitoring area.

In an advantageous development of the invention, it is proposed that the detection unit define a monitoring area close to the tool and a monitoring area remote from the tool relative to a tool, and in at least one monitoring mode determine the speed of an object moving in the tool-remote monitoring area. This is advantageous in particular with regard to the intrinsic limitation of the evaluation speed of the recognition unit, to the reaction time of an actuator unit and to the inertia of an active object to be stopped, which require early detection of a critical movement of a monitored object, such as a slipping motion of human tissue or an approach of human tissue to an active object of the machine tool. A "tool-related" monitoring area "relative to a tool" is to be understood in particular as a monitoring area, which is preferably made up of points which have a smallest distance to the tool which is at most a first maximum value, with a tool removal "Surveillance area is to be understood a monitoring area, which is composed at least of points that have a smallest distance to the tool, which is greater than the first maximum value and preferably at most a second, compared to the first maximum value greater maximum value Surveillance area may overlap or may be formed separately from each other, while being separated from each other by another surveillance area.

It is also proposed that the monitoring areas each have a different operating mode of the machine tool is assigned, whereby a high flexibility in the application of the machine tool can be achieved.

In a preferred embodiment of the invention, it is proposed that at least one of the monitoring areas is assigned a warning mode of the machine tool. As a result, it is advantageously possible to initiate pre-protective measures when a potentially dangerous application situation is detected, before an operator is in acute danger. In this connection, an advantageous warning effect and a high level of safety can be achieved if the recognition unit, in cooperation with a machine tool drive unit for driving a tool, is provided for slowing down a tool drive in the warning mode.

Furthermore, it is proposed that at least one of the monitoring areas is assigned a removal of a driven tool from the monitoring area, whereby a potential risk of injury can be effectively eliminated. The "removal" of the driven tool, which is preferably carried out by means of an actuator unit operatively connected to the detection unit, in particular by an adjustment of the driven tool in a safety position outside the monitoring area, such as by means of a countersinking of the driven tool below a machine tool work surface, by a shutdown of the drive of the tool and / or by covering a cutting edge of the tool can be realized.

In a preferred embodiment of the invention it is proposed that at least one of the monitoring areas is assigned a safety shutdown of the machine tool, whereby a high operating safety of the machine tool can be achieved.

It is also proposed that the recognition unit makes it possible to distinguish between human or animal tissue on the one hand and wood or metal or plastics on the other hand, wherein different processes can be initiated depending on the type of material detected. If human tissue is detected, the safety measures described above can be initiated. When a workpiece to be machined is detected, detection operations for characterizing a workpiece state, such as a humidity, a thickness, a feed speed, etc., may be initiated.

Advantageously, the recognition unit comprises a computing unit which is provided to recognize the application situation by an evaluation of parameters based on a fuzzy and / or neural logic. With the aid of a blurred logic, the arithmetic unit can quickly evaluate a large and complex amount of information on the basis of the detected signal. In particular, a fuzzy logic represents a logic that assigns a probability value in the interval between 0 (false) and 1 (true) to the occurrence of a specific event. By a neural logic advantageous self-learning functions of the machine tool monitoring device can be achieved.

In an advantageous embodiment of the invention, it is proposed that the recognition unit has a database in which a set of parameters an application situation is assigned. A particularly fast detection process of an application situation can advantageously be achieved by examining a correlation between the acquired parameters and an application situation.

Furthermore, a method for detecting an application situation in an application process of a machine tool is proposed, in which for detecting the application situation at least one parameter from the detection of human or animal tissue is detected, whereby a high level of safety can be achieved in the application of the machine tool.

drawing

Further advantages result from the following description of the drawing. In the drawing, an embodiment of the invention is shown. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Show it:

1 shows a table saw in a view from above with a monitoring device for monitoring monitoring areas,

2 is a schematic representation of the monitoring device,

3 shows an ultra-wideband radar signal radiated by the monitoring device,

4 shows a database of the monitoring device with application situations,

5 the detection of movement characteristics of a hand moving in a surveillance area, Fig. 6, the detection of the presence of the hand in another monitoring area and

Fig. 7, the detection of the presence of the hand in a tool-near monitoring area.

Description of the embodiment

FIG. 1 shows a machine tool 10 in the form of a table saw in a view from above. This one has as

Saw blade running tool 12, which is driven in an operation by means of a shown in Figure 2, designed as an electric motor machine tool drive unit 14, which is arranged within a non-visible motor housing. For placing, in particular for placing a workpiece 16 to be machined (see FIG. 5), the machine tool 10 is provided with a machine tool working surface 18 formed by a saw table. In a basic installation position of the machine tool 10 shown in FIG. 1, the machine tool working surface 18 is aligned horizontally. The tool 12 projects out of the motor housing through a gap 20 recessed in the machine tool working surface 18 in the vertical direction.

The machine tool 10 is further provided with a machine tool monitoring device 22. This has a recognition unit 24, which is provided for detecting an application situation in an application of the machine tool 10. In particular, the recognition unit 24 is designed to detect the presence of a human body part in a danger zone as well as one with respect to a potential one Injury to recognize critical movement of the body part. For this purpose, the recognition unit 24 is provided with a plurality of ultra-wideband radar sensors 26, 28.1 to 28.3 and 30.1 to 30.3. They each have an ultra-wideband radar antenna 32, which is provided for the emission or for receiving an ultra-wideband radar signal.

The detection unit 24 with the design of the ultra-wideband radar sensors 26, 28, 30 defines three different monitoring areas 34, 36, 38 for monitoring an application process of the machine tool 10. The boundaries of the Ü monitoring areas 34, 36, 38 in the machine tool work surface 18 are shown schematically by dotted lines. The monitoring areas 34, 36, 38 extend horizontally in the machine tool work surface 18 as well as vertically upwards, i. they have a height relative to the machine tool work surface 18. For the sake of clarity, the monitoring areas 34, 36, 38 are schematically delimited by means of sharp lines. The monitoring areas 34, 36, 38 may form overlapping areas in pairs, each of which extends in a zone of the machine tool work surface 18 on either side of one of the imaginary boundary lines.

A first tool-near monitoring area 34 corresponds to a tool area which extends in the immediate vicinity of the tool 12 and in this case adjoins the outer contour of the tool 12. In particular, the first monitoring area 34 is composed of points which have a minimum distance to the tool 12 of at most Di cm, the distance Di preferably being at most 2 cm. Which he- Identification unit 24 also defines a second, remote tool monitoring area 36, which adjoins the first, near the tool monitoring area 34 and this encompasses. It is composed at least of points which have a smallest distance to the tool 12, which is greater than Di cm and maximum D2 cm, wherein the distance D2> Di, for example, 15 cm. Furthermore, the detection unit 24 defines a third, remote tool monitoring area 38, which adjoins the second monitoring area 36, this encompasses and at least composed of points that have a minimum distance from the tool 12 of at least D ₂ cm. The monitoring regions 34, 36, 38 are arranged substantially in front of the tool 12 in a workpiece sliding direction 40 into which a workpiece 16 to be machined is pushed on the tool working surface 18. In this case, an object moving in the workpiece sliding direction 40 onto the tool 12 successively engages in the third monitoring area, in the second and finally in the first monitoring area. The embodiment of the monitoring areas 34, 36, 38 shown in FIG. 1 is exemplary. It can by the

Design of the ultra-wideband radar sensors 26, 28, 30 other forms of monitoring areas 34, 36, 38 can be achieved.

The first tool-near monitoring area 34 is defined by means of the ultra-wideband radar sensor 26. The monitoring area 36 is assigned to three ultra-wideband radar sensors 28.1 to 28.3, wherein the corresponding ultra-wideband radar antennas 32 are designed in a first antenna array 42. The monitoring area 38 is assigned to three ultra-wideband radar sensors 30.1 to 30.3, wherein the corresponding ultra-wideband radar antennas 32 are assigned in a second Tennenarray 44 are set. In the considered case, the antenna arrays 42, 44 are designed as phase-variable antenna arrays. In this case, within an antenna array 42, 44, relative phase positions between transmission signals generated by the individual, the corresponding antenna array 42, 44 forming ultra-wideband radar antennas 32 are controlled. In this case, by means of constructive and / or destructive interference, a transmission signal for radiation in a preferred transmission direction can be bundled. The control of the relative phase angles by means not shown in detail phase shifting elements.

FIG. 2 shows the recognition unit 24 of the machine tool monitoring device 22 in a schematic view. The detection unit 24 comprises the ultra-wideband radar sensors 26, 28, 30, each comprising an ultra-wideband radar antenna 32. An ultra-wideband radar signal 46 radiated from the ultra-wideband radar antenna 32 of the ultra-wideband radar sensor 26, which is shown in FIG. 3, is generated by means of a signal generating unit 48 and fed into the ultra-wideband radar antenna 32. The ultra-wideband radar antennas 32 of the antenna array 42 are associated with a common signal generation unit 50, while the antenna array 44 is associated with a signal generation unit 52. The ultra-wideband radar signal 46 radiated from one of the ultra-wideband radar antennas 32 is shown in a spectral representation in FIG. 3, wherein the amplitude A is plotted on the Y-axis and a frequency V on the X-axis. The ultra-wideband radar signal 46 is transmitted at a center frequency V _M of 5 GHz and a signal bandwidth Δv of 2 GHz around this center frequency V _M. In this case, a subfrequency V ₁ = 4 GHz and an O berfrequenz V ₂ = 6 GHz.

After reflection on a monitored object, the ultra wide band radar signal 46 is received as a receive signal 54 from one or more of the ultra wideband antennas 32. After receiving this is filtered in a signal processing unit, not shown, amplified, converted into a digital form and then given to a computing unit 56 of the detection unit 24 for evaluation. The recognition unit 24 also has a memory unit 58 in which a database 60 (see FIG. 4) with monitoring information is stored. The arithmetic unit 56 preferably has at least one microprocessor or it may be designed as a microprocessor. Furthermore, a signal processing software is stored in the memory unit 58, which is used to evaluate the received signal 54 and is executed by the arithmetic unit 56.

The detection unit 24 is also operatively connected to an actuator unit 62, which can trigger safety measures from a further unit of the machine tool 10 on the basis of a detection signal of the detection unit 24. In particular, the actuator unit 62 is in operative connection with the machine tool drive unit 14, so that based on a detection signal, a tool drive performed can be adapted or stopped to an application situation. The Aktorikeinheit 62 may also be provided for driving further, not shown securing means. In particular, the actuator unit 62 can drive safety means which serve to lower the tool 12 below the tool dimensions. sinking work surface 18. There may be provided further security means which serve to cover the cutting edge of the tool 12, such as a protective hood. The recognition unit 24 is also operatively connected to an output unit 64, which is provided to warn the operator in an optical, acoustic and / or haptic manner.

FIG. 4 shows the database 60. It is assumed that an operator wants to carry out a sawing of the workpiece 16, which is shown in FIG. For this purpose, the workpiece 16 is placed on the machine tool work surface 18. This application situation is referred to as application situation 66 in FIG. The setting up of the workpiece 16 induces a change in the dielectric surrounding the detection unit 24, which is reflected in a change in the reception signal 54. For example, after setting up a resonant frequency in the frequency spectrum of the received signal 54 is shifted. The arithmetic unit 56 can assign the application situation 66 to this detected received signal 54. This is done by means of the database 60. In this table, characteristic values, for example A ₃ , B ₂ , etc., are assigned to an application situation A or B etc. in an assignment table 68. These characteristics correspond to a signal pattern, ie a parameter or a set of characteristic parameters, such as a signal amplitude, the position of an amplitude maximum, etc., which each characterize a spectrum of the received signal 54 typical for an application situation, or they can be characteristic quantities, such as described below, characterize the movement of a monitored object relative to the tool 12. Starting from the detected received signal For example, the computing unit 56 examines a correlation between the received signal 54 and the signal patterns until a signal pattern 70 having the greatest correlation with the received received signal 54 is determined. The determination of the signal pattern 70 and therefore of the applicable application situation 66 is performed by the arithmetic unit 56 by means of a method of fuzzy logic (fuzzy logic) for evaluating the spectrum of the received signal 54.

In the database 60 in a further allocation table 72 application situations A, B, C, etc. Procedures I, II, III, etc. are assigned for the workpiece machining. If an application situation is recognized by the computing unit 56, it is possible to react to this application situation by the actuator unit 62, if necessary, modifying a course of the workpiece machining in accordance with the procedure. For example, the application situation 66 is assigned a procedure 74, after which a tool drive is followed up unchanged.

To extend the database 60 with new application situations and new procedures for these application situations, a learning mode of the machine tool is provided. In this mode, application situations may be deliberately created by the operator, and the computing unit 56 may independently learn to recognize such application situations and determine which policies are appropriate for those application situations. In this case, the arithmetic unit 56 learns to correlate these application situations with one or more signal patterns in each case. For this purpose, the arithmetic unit 56 operates in this mode on the basis of a neural logic, which allows such a self-learning function. there The operator can set a security level at any time until a desired action for a particular application situation is reached. This can be automatically stored in the database 60.

The mode of operation of the machine tool monitoring device 22 will be described in more detail with reference to FIGS. 5 to 7. The penetration of the workpiece 16 into the monitoring area 38 is detected by the detection unit 24. Here, by means of the recognition unit 24, as described above, based on signal patterns of the database 60, a distinction is made between human or animal tissue on the one hand and wood or metal or plastics on the other hand. If the workpiece 16 is detected from wood, detection processes are initiated by means of the ultra-wide radar sensors 26, 28, 30, which are used to determine e.g. a dimension of the workpiece 16, in particular the workpiece thickness, are used by the feed movement in the workpiece sliding direction 40 or the wood moisture. After starting a tool drive is monitored by at least one ultra-wideband radar sensor 26, 28 and 30, the tool 12 on the number of revolutions and a potential imbalance.

If the hand of the operator is now detected in the monitoring area 38, detection processes are initiated which serve to avoid contact of the hand with the rotating tool 12. If a rapid increase in speed or a high instantaneous speed of human tissue to the rotating tool 12 is detected in the monitoring area 38 remote from the tool, so that even with a possible subsequent decrease in speed, the contact with the Tool 12 is unavoidable, then already in this zone, for example, a shutdown of the machine tool drive unit 14 done. The recognition unit 24 detects the position of the hand in the monitoring area 38. Furthermore, the recognition unit 24 carries out a speed determination by detecting movement characteristics which characterize the movement of the hand relative to the rotating tool 12. By detecting the position of the hand relative to the tool 12 at different times, a direction of movement 76, the instantaneous value of the speed and the acceleration of the hand are detected by means of the arithmetic unit 56. The presence of at least one of the following features, namely the direction of movement 76 pointing to the tool 12, a current value of the speed and / or the acceleration above a predetermined one

Threshold value 78 (see FIG. 4), or the presence of any combination of these features, is assigned to an application situation 80 by means of the database 60. This in turn is assigned to a procedure carried out as a safety measure 82, in which the actuator unit 62 actuates a safety shutdown of the machine tool 10, specifically of the machine tool drive unit 14. In this case, the arithmetic unit 56 serves as a means 84, which, in particular via the database 60, assigns to a detected movement feature of the monitored hand a safety measure, namely the safety shutdown of the machine tool drive unit 14. As described above, the instantaneous value of the speed and / or the acceleration under two stages is classified as "slow" and "fast" with the aid of the means 84 designed as a computing unit 56, by exceeding the value Threshold 78 is examined. Further, middle stages are conceivable.

The velocity determination, i. the detection of at least one movement feature takes place in the monitoring area 38, which corresponds to the tool-remote monitoring area with the largest minimum distance to the tool 12. In this case, due to the remaining distance of the hand to the tool 12, the safety shutdown can be made in good time, so that contact of the hand with the tool 12 in its driven state can be avoided. This type of detection in an outer zone already provides a longer time for deactivating the tool drive.

The further monitoring areas 34, 36 are assigned different operating modes of the machine tool 10. In particular, the monitoring area 36 is assigned a warning mode. If, as shown in FIG. 6, the operator's hand is detected in the monitoring area 36, then in a first warning mode the detection unit 24 triggers a warning output by means of the output unit 64. In this warning mode or in another warning mode, the operator is warned in cooperation with the machine tool drive unit 14 by slowing down the tool drive, ie by reducing the rotational speed during the rotation of the tool 12. The tool-near monitoring area 34 is an actuator mode of the machine tool 10 assigned. If, as shown in FIG. 7, the presence of the hand in the monitoring area 34 close to the tool is detected, then by means of Actuator unit 62 immediately triggered a safety shutdown of the machine tool drive unit 14.

The machine tool monitoring device 22 can be used to advantage in other stationary machine tools, such. for band saws, chop saws, panel saws, pull saws, etc.

Claims

claims

1. Machine tool monitoring device with a detection unit (24) for detecting an application situation (66, 80) in a machine tool (10), characterized in that the detection unit (24) enables a position and / or speed determination.

2. Machine tool monitoring device according to claim 1, characterized by at least one ultra-wideband radar sensor (26, 28, 30).

3. Machine tool monitoring device according to claim 1 or 2, characterized in that the position and / or speed determination is a position and / or velocity determination of human or animal tissue.

4. Machine tool monitoring device according to one of the preceding claims, characterized in that the detection unit (24) comprises means (84) which is intended to assign a movement feature of a monitored object at least one security measure (82).

5. Machine tool monitoring device according to claim 4, characterized in that at least one movement feature a safety shutdown of the machine tool

(10) is assigned.

6. Machine tool monitoring device according to one of the preceding claims, characterized in that the detection unit (24) comprises means (84) which is intended to classify a movement feature of a monitored object.

7. Machine tool monitoring device according to one of the preceding claims, characterized by an antenna nenarray (42, 44).

8. Machine tool monitoring device according to claim 7, characterized in that the antenna array (42, 44) is designed as a phase-variable antenna array.

9. Machine tool monitoring device according to claim 7 or 8, characterized in that the antenna array (42, 44) comprises at least one ultra-wideband radar antenna (32).

10. Machine tool monitoring device according to one of the preceding claims, characterized in that the detection unit (24) defines at least two monitoring areas (34, 36, 38) for monitoring an application process of the machine tool (10).

11. Machine tool monitoring device according to claim 10, characterized in that the detection unit (24) relative to a tool (12) a tool-near monitoring area (34) and a tool-far monitoring range (38) determines and in at least one monitoring mode, a speed determination of a remote tool in the Monitoring area (38) moving object takes place.

12. Machine tool monitoring device according to claim 10 or 11, characterized in that the monitoring areas (36, 38) each have a different operating mode of the machine tool (10) is associated.

13. Machine tool monitoring device according to one of claims 10 to 12, characterized in that at least one of the monitoring areas (36) is associated with a warning mode of the machine tool (10).

14. Machine tool monitoring device according to one of

Claims 10 to 13, characterized in that the detection unit (24) - in cooperation with a machine tool drive unit (14) for driving a tool (12) - is provided for slowing down a tool drive in the warning mode.

15. Machine tool monitoring device according to one of claims 10 to 14, characterized in that at least one of the monitoring areas (34) is associated with removing a driven tool (12) from the monitoring area (34).

16. Machine tool monitoring device according to one of claims 10 to 15, characterized in that at least one of the monitored areas (34) is associated with a safety shutdown of the machine tool (10).

17. Machine tool monitoring device according to one of the preceding claims, characterized in that the detection unit (24) makes it possible to make a distinction of human or animal tissue on the one hand and wood or metal or plastics on the other hand.

18. Machine tool monitoring device according to one of the preceding claims, characterized in that the recognition unit (24) comprises a computing unit (56) which is provided to the application situation (66, 80) by a based on a blurred and / or neural logic Evaluation of parameters to recognize.

19. Machine tool monitoring device according to one of the preceding claims, characterized in that the recognition unit (24) has a database (60), in which a set of parameters an application situation (66, 80) is associated.

20. A machine tool with a machine tool monitoring device according to one of the preceding claims.

21. Ultra-broadband radar sensor for detecting an application situation in a machine tool according to claim 20.

22. A method for detecting an application situation (66, 80) in an application process of a machine tool (10), characterized in that for detecting the application situation (66, 80) at least one parameter from the detection of human or animal tissue is detected.