AU731456B2

AU731456B2 - Device for damping vibrations of selective cut heading machines

Info

Publication number: AU731456B2
Application number: AU51097/98A
Authority: AU
Inventors: Peter Kogler; Gottfried Siebenhofer; Nikolaus Sifferlinger
Original assignee: Voest Alpine Bergtechnik GmbH
Current assignee: Sandvik Mining and Construction GmbH
Priority date: 1996-12-04
Filing date: 1997-11-20
Publication date: 2001-03-29
Anticipated expiration: 2017-11-20
Also published as: EP0943051A1; ATE198781T1; WO1998025007A1; ES2154475T3; ATA211996A; EP0943051B1; DE59702937D1; ZA9710825B; AT407071B; AU5109798A

Abstract

The invention relates to a device for damping vibrations in part-face cutting machines (1), comprising an extension arm (3) pivoting round two axes (5, 9) with cutting tools (7) rotationally fitted thereon. Said device has a hydraulic regulating drive mechanism (6) which is impinged upon by fluid via a valve arrangement. Sensors (13 or 14) are provided in order to detect vibrations, accelerations, load and/or position of the cutting arm (3) and which trigger a corresponding compensation of the regulating drive mechanism formed by the hydraulic cylinder piston units (6) by means of a control device (16). The position of the extension arm (3) is thus kept basically constant round the vertical rotational axis (9) when the swing gear swivels.

Description

1 Device for Damping Vibrations of Selective Cut Heading Machines The invention relates to a device for damping vibrations of selective cut heading machines comprising an extension arm capable of pivoting about two axes, on which cutting tools are rotatably mounted, wherein the extension arm is respectively connected with one pivoting actuator for each of the pivot axes, wherein at least one hydraulic pivoting actuator is capable of being fed with fluid via a valve arrangement and fluid is supplied to the actuator as a function of values measured by sensors, at least one sensor being connected with the exension arm.

When extracting hard material, the cutting tools are subjected to high shock-like loads depending on the driving speed and the rotational speed of the cutting heads, and it can already be taken, for instance, from AT-377 056 to arrange shock sensors as measuring quantities for the load exerted on the tools, via which the pivoting speed and/or the rotational speed of the tools may subsequently be influenced for the purpose of reducing the load exerted on the tools. To this end, a shock sensor was provided in that known configuration, whose signals were connected to the pivoting actuator of the cutting arm and, in particular, the controllable valves of a hydraulic pivoting actuator, via an electronic control means.

In case of excessive vibrations, the excavation output of the cutting machine was accordingly reduced.

From DE-34 27 962 a device has already become known, by which the extension arm adjusting means for winning and driving machines could be hydraulically braced. Also that configuration is based on the idea that selective cut heading machines, in particular roll cutting machines, are exposed to particularly strong vibrations when running against hard mineral layers. The shocks and vibrations are transmitted onto the extension arm via the cutting tools biting into the 2 material, wherein such shocks may cause pronounced vibrations of the cutting arm due to the elasticity of the pressure cylinder of the adjusting actuator for the extension arm. If, to make things worse, resonance occurs within the system, such vibrations may lead to destruction. By the measures to be taken from DE-34 27 962, the pressure in the adjusting cylinders is raised, yet this does not solve to a sufficient degree the underlying problem of the elasticity of the pressure cylinders.

The invention aims at suggesting a simple device optionally capable of being retrofitted also subsequently, by which the effective damping of vibrations of selective cut heading machines is feasible. The device according to the invention is to be able to do with a minimum of accessory parts and be designed in a compact manner and, in addition, influence the efficiency and performance of the pivoting actuator for the extension arm as little as possible. To solve this object, the device according to the invention essentially consists in that at least one sensor for detecting shocks, acceleration, loads and/or the position of the arm is connected with the extension arm or the hydraulic pivoting actuator, the signalling lines of which sensor are connected to a control means, which control means is connected with a hydraulic circuit for unilaterally powering that pivoting actuator whose position during the advance movement of the cutting tools is kept substantially constant, in order to compensate for the recorded evasion of the extension arm. When cutting by means of a selective cut heading machine, cutting after penetration usually is effected in a manner that one of the two pivoting actuators is blocked in its position, whereas the advance movement is induced via the second actuator. When cutting in the horizontal direction, the vertical pivoting actuator is thus fixed in the desired position, driving being effected by horizontal pivoting of the arm. By making available the measured signals of the sensor to a control means intended to power that actuator which is to be kept in its respectively 3 chosen position, inadmissible peak loads can be eliminated.

Thus, according to the invention, only one working volume of the pivoting actuator intended to be kept in a constant position, for instance the vertical pivoting actuator, will be powered if an evasion is registered such that even shocks can be counteracted in a compensating manner without affecting the cutting performance. In this case, controlling may sensitively be adapted to the respectively recorded direction of the elevated load. The compensating control pulses, thus, cause a cyclic readjusting movement in order to counteract evasions such that, in the main, the cutting arm can be kept steadier and shocks will be damped. Since an acute predetermined high pressure level has to be made available to such compensating powering of a working volume of a cylinder piston unit of a pivot actuator, the configuration in a particularly advantageous manner has been further developed to the extent that, in addition to the hydraulic pump for the hydraulic pivoting actuator, a fluid pressure tank capable of being respectively connected with one working volume of the pivoting actuator is provided for compensating for the evasion of the arm. From a fluid pressure tank, the acute pressure level necessary for compensation may be provided without involving additional interferences and feedbacks on the pump of the hydraulic actuator. From the pressure tank, extremely acute pressure corrections may be provided such that the hydraulic pump, which is required for the pivoting actuator, will be decoupled from such peak loads.

In principle, it is feasible to control such a pressure tank in combination with a separate valve arrangement for the respective compensation. Yet, in a particularly simple manner, also the valve arrangement employed for the pivoting actuator of the extension arm may be directly used as a valve arrangement for the desired compensation, thereby offering a particularly simple mode of construction.

4 In the following, the invention will be explained in more detail by way of an exemplary embodiment illustrated in the drawing. Therein, Fig. 1 is a schematic side view of a selective cut heading machine and Fig. 2 is a connection diagram for the hydraulic circuit.

In Fig. 1, a selective cut heading machine which is displaceable on a crawler mechanism 2 is denoted by 1.

An extension arm 3 is mounted on a pivoting mechanism 4 so as to be pivotable in height about a substantially horizontal axis 5. The pivoting actuator 6 for this shift about the pivot axis 5 is constituted by at least one hydraulic cylinder piston unit articulately connected to the cutting arm 3. The cutting arm 3 carries rotatably mounted cutting heads 7, which are pivotable in height in the sense of the double arrow 8.

Advance movement is effected by the pivoting mechanism 4 being pivoted about the substantially vertical pivot axis 9.

Further, a loading means 11 is hinged to the machine frame A conveying means 12 is schematically illustrated on the rear end of the machine.

A sensor 13 is provided on the cutting arm. Alternatively or additionally, a further sensor 14 may be arranged on the hydraulic pivoting actuator 6 or in the pivot axis 5, which sensor serves to dectect shocks, accelerations, loads and/or the position of the cutting arm or extension arm 3. The signals of the sensor 13, or of the sensor 14, are fed to a control means 16 via a signalling line 15. The control means is connected with a valve arrangement for the hydraulic pivoting actuator 6, as is illustrated in more detail in Fig.

2.

From Fig. 2, a valve arrangement for operating the adjusting actuator 6 is schematically apparent. In order to pivot the Scutting arm 3 in terms of height in the direction of the

O

5 double arrow 8, the hydraulic slide 17 may be brought into the respective position, thereby enabling upward or downward pivoting. In doing so, fluid is supplied from a tank 18 via a pump 19 to the valve arrangement and hence, depending on the position of the slide valve, to the respective working volume of the hydraulic cylinder piston units of the pivoting actuator 6. Appropriate nonreturn valves or control valves, which are schematically denoted by 20, are arranged in the duct leading to these vertical pivoting cylinders. In doing so, the cylinder volumes 21 or 22 are selectively powered for pivoting. In the position of the hydraulic slide valve 17 depicted in Fig. 2, the ducts between the pump 19 and the cylinder volumes 21 and 22, respectively, are separated and locked such that the selected vertical position of the extension arm 3 is fixed for pivoting the cutting arm 3 in a substantially horizontal direction. In that position, depending on the nature of the rock or operating conditions, a more or less high force may start to act on the respectively locked working volumes 21 and 22, respectively, of the hydraulic cylinder piston units, vibrating conditions not being exluded because of the compressibility of the fluid. If such undesired operating conditions are checked back by the sensors 13 and/or 14 of the control means 16, the additional control unit 23 is triggered, whereby fluid is pressed out of a pressure tank 24 into the respective one of the two cylinder volumes 21 and 22 in order to counteract those reaction forces. Depending on the recorded evasion of the extension arm 3 in the direction of the double arrow 8, the respectively opposite working volume 21 or 22 is set into communication with the pressure tank 24 in order to counteract vibrations and safely keep the cutting arm 3 in its selected vertical position.

Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification, they are to be interpreted as specifying the presence of the stated features, integers, steps or components referred to, but not to preclude the presence or addition of one or more other feature, integer, step, component or group thereof.

a 28/06/99, tdl0593.pg5a.doc,2

Claims

1. A device for damping vibrations of selective cut heading machines comprising an extension arm capable of pivoting about two axes on which cutting tools are rotatably mounted, wherein the extension arm is respectively connected with one pivoting actuator for each of the pivot axes, wherein at least one hydraulic pivoting actuator is capable of being fed with fluid via a valve arrangement and fluid is supplied to the actuator as a function of values measured by sensors (13, 14), at least one sensor being connected with the exension arm characterized in that at least one sensor (13, 14) for detecting shocks, acceleration, loads and/or the posiiton of the arm is connected with the extension arm or the hydraulic adjusting actuator, the signalling lines (15) of which sensor are connected to a control means which control means (16) is connected with a hydraulic circuit for unilaterally powering that pivoting actuator whose position during the advance movement of the cutting tools (7) is kept substantially constant, in order to compensate for the recorded evasion of the extension arm

2. A device according to claim i, characterized in that, in addition to the hydraulic pump (19) for the hydraulic pivoting actuator a fluid pressure tank (24) capable of being respectively connected with one working volume (21, 22) of the pivioting actuator is provided for compensating for the evasion of the arm

3. A device according to claim 1 or 2, characterized in that the valve arrangement for the pivoting actuator of the extension arm is used as said valve arrangement. -7-

4. A device for damping vibrations of selective cut heading machines, substantially as described herein and with reference to the accompanying drawings. Dated this 2 nd day of January, 2001. VOEST-ALPINE Bergtechnik Gesellschaft m.b.H. By their. Patent Attorneys: CALLINAN LAWRIE o r r r. r r r r r~ C C r r C V .J o 2/01/01, b110593.spe,7