The present invention is based on a machine tool having a safety unit. The present invention is further based on a method regarding a machine tool.
A circular-saw bench having a safety device is known. The safety device is provided with a sensor unit and is used to monitor a danger zone in the immediate surrounding area of a saw blade with the aid of the sensor unit.
The exemplary embodiments and/or exemplary methods of the present invention is based on a machine tool having a safety unit.
It is provided that the machine tool have a calibration unit for calibrating the safety unit.
The safety unit may thereby be adapted advantageously to a work environment when using the machine tool. In particular, the safety unit has a sensor unit and an actuator unit, which is provided to trigger a safety procedure as a function of a characteristic quantity detected by the sensor unit. False trippings of the actuator unit based on a work environment altered relative to a factory setting or an earlier use of the machine tool may be avoided particularly advantageously due to the calibration unit. This altered work environment may be characterized by a changed ambient parameter such as temperature, moisture, in-house network impedance and/or by changed clothing of a do-it-yourselfer or craftsman. A “calibration” of the safety unit is to be understood in particular as a procedure in which a reference value is determined for at least one characteristic quantity detectable by the safety unit, especially by the sensor unit. In particular, this reference value may take the form of a threshold value of the characteristic quantity, above or below which an operation is triggered with the actuator unit. The calibration expediently represents a procedure which takes place prior to a tool of the machine tool being driven, and which may work with an actuator unit decoupled from a sensor unit of the safety unit.
In one development of the exemplary embodiments and/or exemplary methods of the present invention, the machine tool has an operator control unit which, in interaction with the calibration unit, is provided for a calibration procedure by an end operator. In this context, an “operator control unit” is to be understood particularly as a unit which is provided to produce a circulation of information between the machine tool and an end operator of the machine tool. To that end, the operator control unit may have at least one output unit for the output of information. An operator control unit which is provided “for” a calibration procedure is to be understood in particular as an operator control unit which is utilized in at least one calibration mode of the calibration unit. In this connection, the calibration unit has one calibration mode in particular, in which a calibration procedure draws upon an operation with the operator control unit, such as an output and/or an input. An “end operator” in this connection is to be understood in particular as a do-it-yourselfer and/or a craftsman who acquires the machine tool for private or commercial purposes. Advantageously, the calibration unit, in interaction with the operator control unit, is used to modify calibration data of a factory calibration performed in a factory during the assembly of the machine tool and/or calibration data of a previous use of the machine tool.
The calibration unit may have a checking unit, which is provided to check a calibration status of the safety unit. Ease of operation may be increased advantageously in this manner. In particular, the existence of a calibration adapted to a work environment may be recognized, thereby making it possible to avoid an unnecessary calibration procedure. A “calibration status” in this context is to be understood in particular as the existence of calibration data, especially as in a stored form. These calibration data may correspond in particular to at least one reference value for at least one characteristic quantity able to be sensed by the safety unit. Furthermore, the calibration data may correspond to a characteristic quantity which is used to characterize a specific work environment like, for example, a characteristic temperature quantity, a characteristic moisture quantity, a quantity characterizing an electrical, magnetic and/or electromagnetic field, etc. A “check” of a calibration status is to be understood especially as a check of calibration data. In particular, by this may be understood a procedure in which existing calibration data are compared to at least one characteristic quantity sensed by the safety unit in a present work environment.
In this connection, great ease of operation may be achieved if the checking unit has at least one automatic checking mode. In this context, the checking unit may be provided to check the calibration status automatically upon start-up of the machine tool like, for example, upon application of voltage to the machine tool.
In addition, it is provided that the safety unit have a sensor unit for sensing a characteristic quantity during a driving of the tool, and the checking unit is provided in order, in a checking mode, to trigger a sensing operation of the sensor unit prior to the tool being driven. Advantageously, it is thereby possible to save on component parts, because a sensor unit which is provided to monitor a danger zone while the tool is being driven, is additionally used to ascertain a change in a work environment in the run-up to the driving of the tool. In this connection, “tool driving” is to be understood particularly as an operating mode of the machine tool in which a tool of the machine tool provided for processing a workpiece is driven by a drive unit like, for example, by an electric motor, into a movement such as a rotation, a pendulum movement, a back-and-forth movement, etc.
An especially safe use of the machine tool may be achieved if the machine tool has a control unit which is provided to control a driving of the tool and which, in at least one operating mode, requires a check of the calibration status in order to start the tool driving.
A calibration status of the safety unit may be checked rapidly and reliably if the machine tool has a memory unit and a control unit which, in interaction with the memory unit, is provided to store calibration data.
In a further embodiment variant of the present invention, the machine tool has an output unit and a control unit which, in interaction with the output unit, is provided to output information as a function of a calibration status of the safety unit, thereby making it possible to further increase the ease of operation. The output unit may be provided for a visual, acoustic and/or haptic output.
The exemplary embodiments and/or exemplary methods of the present invention is further based on a method regarding a machine tool which has a safety unit.
It is provided that a calibration status of the safety unit is checked after a start-up of the machine tool by an end operator, which means the ease of use and the application safety of the machine tool may be increased advantageously.
An especially high level of safety may be achieved if the check is required in order for the drive unit of the machine tool to start driving the tool.
It is further provided to calibrate the safety unit with the aid of a reference object which takes the form of a machine-tool accessory, thereby permitting an especially easy calibration. A “machine-tool accessory” is to be understood in particular as an object which is designed to be separate or detachable from the machine tool, and is manipulable by an end operator to perform the calibration.
Further advantages are derived from the following description of the drawing. The drawing shows an exemplary embodiment of the present invention. The drawing, the specification and the claims contain numerous features in combination. One skilled in the art will advantageously examine the features individually, as well, and combine them to form further useful combinations.
Machine tool 10 is further provided with a machine-tool safety device 26. It has a safety unit 30, which is used to monitor a danger zone 28 in the immediate vicinity of tool 16. To that end, safety unit 30 has a sensor unit 32. Safety unit 30 is shown in greater detail in
Machine-tool safety device 26 of machine tool 10 is shown in greater detail in a schematic representation in
In the exemplary embodiment discussed, machine tool 10 is implemented as a manual machine tool. A construction of machine tool 10 as a stationary device such as a table saw, cross-cutting and miter saw, etc., is likewise conceivable. If, in a further embodiment, machine tool 10 is implemented as a stationary device, actuator unit 40 may be used to activate a disabling arrangement to disable a movable tool bearing unit such as a retraction arm in the case of a miter saw.
In addition, machine-tool safety device 26 has a control unit 42 which is an operative connection with sensor unit 32, actuator unit 40 and operator control unit 34. Control unit 42 has an evaluating arrangement which is provided to evaluate a characteristic quantity sensed by sensor unit 32, and which is used in particular to control actuator unit 40 based on an evaluation process. Control unit 42 may have a microprocessor or a microcontroller, or may take the form of a microprocessor or microcontroller.
Machine-tool safety device 26 further has a calibration unit 44 which is used to calibrate safety unit 30.
Safety unit 30 is calibrated in the factory during assembly of machine tool 10. In so doing, threshold values of characteristic quantities which are detectable by sensor unit 32 are defined. If a threshold value is reached during a driving of the tool and upon the evaluation of a detected characteristic quantity, then control unit 42 transmits a control signal to actuator unit 40, which undertakes safety measures. During use of machine tool 10, a work environment may differ from an environment present during the factory calibration. Because of the altered work environment, false trippings of actuator unit 40 may thereby impair a work operation with machine tool 10. Calibration unit 44 is advantageously provided to modify calibration data of a factory calibration or of a previous use of machine tool 10 with the aid of a control action by an end operator.
A practical application of machine tool 10 is described in greater detail with reference to a flow chart in
It is assumed that in a step 48, an operator puts machine tool 10 into operation by connecting it to a mains current supply. In a next step 50, it is checked whether existing calibration data for a machining using machine tool 10 are adapted to the work environment shown in
The checking mode of checking unit 52 described here is an automatic mode, which takes place automatically after machine tool 10 is put into operation by an end operator. In a further embodiment variant, it is conceivable that a check may be carried out upon selection by the operator. In the run-up to and during the checking operation, actuator unit 40 prevents a start of tool driving by switching elements 20, 24. As can be gathered from the flow chart, control unit 42 requires a checking operation to start the driving of the tool.
In the example considered, a sensing operation of sensor unit 32 is triggered for the checking, the sensor unit likewise being used to monitor danger zone 28 while the tool is being driven. In an embodiment variant, it is conceivable for machine-tool safety device 26 to have a sensor device which is in addition to sensor unit 32 and which is called up in the event of a checking operation by checking unit 52. Sensor unit 32 and/or an additional sensor device is/are able to sense characteristic quantities which are a function of the work environment such as a characteristic temperature quantity, a characteristic moisture quantity, a characteristic impedance quantity, etc. If sensor unit 32 is provided for sensing with the aid of a transmitted sensing signal, a correlation may occur between the sensing signal in its received form and the sensing signal in its transmitted form like, for example, by an evaluation of the level of the received sensing signal.
If the existing calibration status is regarded by checking unit 52 as suitable for the work environment present in
A first calibration mode is shown in
If the calibration procedure is accomplished, the operator is informed in a step 61 by output unit 36. If the calibration procedure has failed, then in a step 64, the operator is prompted by output unit 36 to repeat the calibration procedure.
After success of the first calibration procedure, further calibration procedures may be carried out. This is illustrated in
A further calibration mode of calibration unit 44 provides that the operator carry out a calibration in a typical work position of machine tool 10 relative to an object to be processed. In this case, machine tool 10 is brought to the object to be processed like, for example, a hedge to be cut and is retained in a proper holding position by the operator. A further calibration mode may also be provided, in which tool 16 is brought into the vicinity of interference object 46.
In another calibration mode, the operator is prompted to carry out a calibration procedure with the aid of a reference object 62. Reference object 62 is a machine-tool accessory, which is supplied together with machine tool 10 (see also
Additional typical danger situations may be simulated in further calibration modes of machine tool 10. In particular, safety unit 30 may be calibrated when an electric cable for supplying machine tool 10 is placed in the vicinity of tool 16.
After the recalibration is accomplished, in step 56, actuator unit 40 enables drive unit 14 to start driving the tool. This tool driving may be triggered by the actuation of switching elements 20, 24 in a step 66.
A sensing operation of sensor unit 32 may be triggered automatically in step 60. Advantageously, however, after notification of the operator in step 58, calibration unit 44 is in a waiting mode, the sensing operation being able to be triggered with the aid of an actuation process by the operator. This may be carried out in a step 68, in which the operator actuates input unit 38. Alternatively, the operator may trigger the sensing operation in step 68 by actuating one of switching elements 20, 24.
The various calibration modes as well as the notifications associated with a calibration procedure may be identified by a coding of output unit 36 such as a color coding with the aid of colored LEDs. In a further embodiment variant, it is conceivable to provide operator control unit 34 with an acoustic output unit, the calibration modes and notifications being denoted by a tone coding and/or a voice message.
In another embodiment variant, it is further conceivable that memory unit 54, in interaction with control unit 42, is provided for storing calibration data which are assigned to at least two different work environments. If machine tool 10 is employed in alternation at two different places of use, after selection by the operator, the calibration data adapted to the respective work environment may be utilized without having to perform a calibration again in each instance.
Number | Date | Country | Kind |
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10 2007 032 221.8 | Jul 2007 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2008/055837 | 5/13/2008 | WO | 00 | 3/29/2010 |