Measuring and testing – Inspecting
Reexamination Certificate
2001-01-11
2004-05-18
Raevis, Robert (Department: 2856)
Measuring and testing
Inspecting
Reexamination Certificate
active
06736019
ABSTRACT:
The present disclosure relates to the subject matter disclosed in the German patent applications Nos. 100 00 954.9 and 100 01 337.6, both of Jan. 17, 2000, and No. 100 24 976.0 of May 19, 2000, the entire specifications of which are incorporated herein by reference and from which priority is claimed.
The invention relates to a monitoring device for checking for a predefined position of a body or for checking for the presence of a body, comprising a pivotal checking element, a motor for driving the checking element and a control device for controlling the pivotal movement of the checking element.
Monitoring devices of this type are known, for example, from DE 30 03 431 C2, DE 43 10 872 A1 or DE 196 08 628 A1.
They are employed in machine tools for example in order to check whether a tool, such as a drill for example, is still in a predefined position or, for example, has broken off, or for checking as to whether a “foreign body” has entered a region in which such a body would constitute a disturbance.
In DE 30 03 431 C2, it is proposed, for the purposes of setting the sensitivity or impact weight on the tool or workpiece of a sensing needle which is seated in the checking element, that the rotational speed of a dc motor and hence the pivotal speed of the sensing needle be altered. Herein, a microcomputer controls the rotational speed and this would be reduced at a predefined number of angular steps prior to a stored reference angular position.
The object of the invention is to improve a monitoring device of the generic kind in such a manner that, commencing from the state of the art, the pivotal movement of the checking element will be effected in a controlled manner in order to be able to set the monitoring device in a universally simple manner.
In accordance with the invention, this object is achieved in a monitoring device of the type described hereinabove in that the control device specifies or indicates the pivotal position of the checking element in dependence on the time.
Firstly, it is thereby known where the checking element is located at any time within the control precision range, and secondly, for every pivotal position, it is known how much time was needed for the checking element to arrive at this position. Hereby, in particular, those times are fixed (within the control precision range) which the checking element needs in order to reach a monitoring region and for passing through the monitoring region. The time, which is needed for detecting a body or for detecting the absence of a body, is thereby fixed and hence not subject to variations. Likewise, the time, which a checking element needs for returning to its starting position, is fixed and varies, at most, within the control precision range. The latter, however, can be determined during the manufacture of the monitoring device in accordance with the invention and, in particular, can be set so small that in practice it is not discernible.
In accordance with the invention, a monitoring device is provided which has constant sampling times, for example, when monitoring tools. Consequently, the monitoring process is not subject to any form of disturbance caused, for example, by the sampling times becoming shorter or longer. In particular, the pivotal movement of the checking element is independent of the “pre-history” of the checking element; larger or smaller frictional moments, which can always occur during the operation of the monitoring device, are compensated by the control of the pivotal movement provided in accordance with the invention by adjusting to a predefined pivotal position-time course in such a manner that the pivotal position of the checking element at a certain time point will lie at a predefined set location.
It is advantageous that the pivotal movement of the checking element be controlled in accordance with a predefined position-time course. Such a course can be produced by the manufacturer and, in particular, programmed into the control device. It is thereby ensured that the checking element will be in defined pivotal positions at defined times.
It is expedient for the controlled value for controlling the pivotal movement of the checking element to be the pivotal position of the checking element at a predefined time, i.e. the controlled value is the predefined course of position against time. In this manner, the time, which is needed for detecting a body or for monitoring a monitoring region, can be set so as to be substantially free of variations.
It is especially advantageous if the pivotal position of the checking element relative to a starting position is known at every time in the pivotal movement of said checking element. A control loop can thereby be formed for effecting a comparison between a reference pivotal position and the actual detected pivotal position so as to move the checking element on the basis of the result of the comparison in such a manner that the pivotal movement will follow a predefined pivotal position-time course as closely as possible.
It is expedient if the time needed by the checking element for its pivotal movement from a first pivotal position into a second pivotal position is fixed. The times, which a monitoring device needs for carrying out a monitoring process, are thereby defined substantially free of variations. It is especially advantageous if the time, which the checking element needs for its pivotal movement commencing from a starting position until arriving at a checking position, is fixed. Furthermore it is advantageous if the time, which the checking element needs for its pivotal movement commencing from a starting position until arriving at a reversal position, is fixed. It is thereby ensured that a monitoring process in accordance with the invention will be effected within a defined time interval.
Furthermore, it is expedient if the time, which the checking element needs for its pivotal movement from a reversal position until arriving at the starting position, is fixed. The time, after which the monitoring device in accordance with the invention will again be ready for use, is thereby defined precisely, i.e. when it is once more in its starting position from which a monitoring process can take place.
The monitoring device in accordance with the invention can be utilised in an extremely simple manner if the predefined position-time course is stored in the control device. The user does not then have to be concerned about appropriate settings, and the monitoring device has fixed times for carrying out the monitoring processes.
In one advantageous variant of an embodiment, a control value (setting value) is a time increment. It is also advantageous if a control value is a pivotal position increment or a pivotal position decrement. The pivotal path of the checking element can be varied in this manner, as can the speed of the checking element by forming a differential quotient and likewise, in a corresponding manner from the formation of a further differential quotient, its acceleration.
Advantageously, the control value is formed, in dependence on a predefined maximum torque. As will be referred to again hereinbelow, it is advantageous if the torque of the checking element is limited so as to prevent it impinging heavily on a body, thereby possibly causing damage thereto or even the destruction thereof. The torque of an electric motor is proportional, in particular, to the control current for the electric motor. Due to the fact that the maximum permissible torque is used for generating the control value, such a torque limiting process can be achieved in a simple manner.
It is especially advantageous if the magnitude of path intervals and/or time increments for the control of the pivotal position of the checking element are matched to the predefined position-time course. It can be advantageous, especially when arriving in a monitoring region, if the control and regulating process is carried out with increased accuracy. This can be achieved, inter alia, by reducing the size of the corresponding path increments and time increments. In certain circumstance
Middex-Electronic GmbH
Raevis Robert
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