Mining or in situ disintegration of hard material – Automatic control; signaling or indicating – Of hard material disintegrating machine
Reexamination Certificate
1999-09-29
2001-07-10
Tsay, Frank (Department: 3672)
Mining or in situ disintegration of hard material
Automatic control; signaling or indicating
Of hard material disintegrating machine
C299S034010
Reexamination Certificate
active
06257671
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for protecting selective cutting machines against overload, in which the selective cutting machine has cutting tools, in particular cutting rollers, rotatably supported on a pivotable cantilevered arm, and the cutting tools and the cutting arm are connected to separate drive mechanisms.
2. Prior Art
Selective cutting machines, having cantilevered arms that are pivotable about at least two axes, as a rule have either cutting heads or cutting rollers. In the case of cutting heads, such cutting heads are usually designed for a particular pivoting speed of the cutting arm, so as to obtain a correct cutting pattern for a predetermined pressure resistance of a test cube on the part of the rock to be worked. Any deviation in pivoting speed from the pivoting speed for which the arrangement of cutters on the cutting head was designed can lead to severe vibrations, which can lead to the breakage of parts and especially of the cutters. Such impermissible vibrations have been detected in accordance with the proposal in German Patent Disclosure DE 33 43 372 A1 by a vibration sensor, and its signals have been evaluated and used for closed-loop control of the drive mechanism of the cutting speed.
However, above all in roller cutting machines, impermissible stresses and overloads are of particular importance, and such stresses cannot be detected correctly by vibration sensors. In roller cutting machines, a relatively wide roller is rotatably supported on the free end of the cutting arm; on pivoting of the cantilevered arm or cutting arm about a substantially vertical axis, the cutting forces act on the cutting or cantilevered arm via a long lever arm. When materials are being worked, it often happens that regions of less hardness or toughness or that are highly brittle are penetrated, and in these regions even large pivoting angles of the cutting arm have still not led to excessive loads, because the material can readily be cut or broken. However, if in certain pivoted positions a higher pressure resistance to a test cube is exerted on material, the result is impermissible stresses, which can cause heavy damage to the machine.
For monitoring impermissible operating states in roller cutting machines, it has previously been proposed that monitoring devices be used, in which the temperature of the liquid circulation of the hydraulic winch, the temperature of certain bearing points, the temperature of the coolant circulation, or the pressure as well has been monitored. Such monitoring devices are described for instance in German Patent Disclosure DE-OS 29 17 054. In German Patent Disclosures DE-OS 31 00 116 and DE-OS 31 06 348, special cutting tools can be found in which a cutting characteristic of the particular rock or mineral can be sampled during cutting by the cutting tool. Such devices are relatively complicated and expensive, because they have to be disposed in the immediate vicinity of the cutters acted upon by the cutting pressure, and the bearing points for pivoting the cutters are subject to correspondingly high wear.
SUMMARY OF THE INVENTION
It is now the object of the invention to create a device of the type defined at the outset, in particular for selective cutting machines with wide cutting rollers, with which device impermissible operating states and any possible overload are detected in a simple and reliable way, so that the risk of permanent deformation of parts of the drive mechanism or even of the cantilevered arm itself can be reliably averted. To attain this object, the especially simple, operationally reliable embodiment according to the invention of the device defined at the outset is characterized substantially in that at least one strain or deformation measuring sensor is disposed on the pivotable cantilevered arm, and its signals are delivered to an evaluation circuit; and that the evaluation circuit is connected at least to the drive mechanisms of the cutting arm and of the cutting tool via control lines. Because only a strain or deformation measuring sensor is disposed on the pivotable cantilevered arm, the effective deformation forces on the cantilevered arm, of the kind that have been observed especially with an eccentric load and in machines with wide cutting rollers when the cantilevered arm is pivoted, can be detected especially simply and reliably, and a suitable open- or closed-loop control of the drive mechanism of the cutting arm or cutting tool can be achieved. With the disposition of the sensor on the cantilevered arm, overloads of such components as bearings, carriages or slideways, which are especially threatened in the presence of severe eccentric loads, can be averted by the suitable open- or closed-loop control of the drive mechanism of the cutting arm or cutting tool.
Especially advantageously, the embodiment according to the invention is further embodied such that the evaluation circuit is additionally connected to the running gear drive mechanism, in particular a track-type running gear drive mechanism, of a traveling selective cutting machine. In roller cutting machines, different operating states, in each of which only some of the various drive mechanisms are simultaneously supplied with energy, are defined exactly. Depending on the operating state, with the device of the invention the requisite open- or closed-loop control provisions can be initiated especially simply.
An especially reliable detection of impermissible forces and thus a reliable detection of any possible overload can be attained in that the sensor is disposed in or on a housing wall of the cantilevered arm.
To enable taking the different operating states of roller cutting machines into account completely and optimally, the embodiment is advantageously such that the drive mechanisms of the selective cutting machine are connected to the evaluation circuit via reporting lines for the operation of the applicable drive mechanism. In this way, all the necessary information is available to the evaluation circuit for affecting actually those particular drive mechanisms with which the possible overload can be reliably averted, with the least possible reduction in cutting or breaking capacity. To that end, the embodiment is advantageously such that the operation of a drive mechanism, signaled via the reporting line, for controlling the applicable drive mechanism to be triggered to avoid an overload is evaluated in the evaluation circuit.
For various operating states, the procedure is advantageously such that the evaluation circuit, in penetration cutting, generates control signals for the drive mechanism of the cutter motor and the displacement drive mechanism, in particular the hydraulic displacement cylinder for the bearing of the pivot axis of a roller cutting machine, or that the evaluation circuit in cutting by a roller cutting device in the vertical direction (shearing), generates control signals for the drive mechanism of the cutter motor and for the pivot cylinder for the vertical pivoting of the cantilevered arm, or that when curves are being cut, control signals for the track-type running gear drive mechanism are generated in addition to the control signals for the cutter motor and the vertical pivoting cylinder. These special operating states, such as penetration cutting, so-called shearing, or curve cutting, can in this way be mastered reliably with only slight corrections and without the possibility of an overload.
Especially reliable detection and correspondingly clear signals of the strain or deformation measuring sensors can be obtained in that the sensor or sensors on the cantilevered arm are disposed closer to the pivot axis of the cantilevered arm and preferably in the one-third of the length of the cantilevered arm adjacent to the pivot axis; this arm is embodied as a box profile frame. In an especially simple way, the embodiment is such that the deformation sensors are embodied as strain measuring sensors or strain gauges fixed to a thin-walled carrier and the carrier plate is fixed
Leitner Walter
Siebenhofer Gottfried
Sifferlinger Nikolaus
Pillsbury & Winthrop LLP
Tamrock Voest-Alpine Bergtechnik Gesellschaft m.b.H.
Tsay Frank
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