Device for correcting the control or the display of the position of a cutting tool of a cutting machine

With cutting machines, having their loading means (7) adapted to be lowered below the running surfaces (11) of the crawlers (2) of the drift advancing machine, there results an erroneous position of the machine on account of lifting the front end of the machine during such lowering movement of the loading means (7). For establishing the correct position of the cutting tool (6) and of the cutting arm (5), corrective signal are used which are released by angular position transmitters (16 or 17, respectively). By means of these angular position transmitters (16 or 17, respectively), the swivelling angle of the loading means (7) relative to the frame (1) or the swivelling angle .theta. of the operating cylinder (9) of the loading means (7) relative to the frame (1), respectively, is measured and the required corrective signal for the angle advance .DELTA..alpha. is calculated (FIG. 3).

The invention refers to a device for correcting the control or the display 
of the position of a cutting tool of a cutting machine, which cutting 
machine has a loading means by means of which the front end of the 
machine, in particular the crawlers of the chassis in their forward area, 
can be lifted off the floor. With such partial cut cutting machines, the 
cutting tool is rotatably supported on a universally swivelable cutting 
arm, and it is already known to represent the position of the cutting tool 
relative to the frame of the cutting machine on a display means comprising 
the nominal profile to be cut, for example in form of a templet. For 
correctly matching the nominal profile, it has already been proposed to 
detect the position of the cutting machine relative to a drift pilot ray 
and to consider erroneous positions of the machine resulting from 
detecting the position relative to a pilot ray for displaying or 
controlling, respectively, the movement of the cutting tool. In more 
simple cases, the machine is, however, used independent of its position 
relative to a pilot ray and with such a procedure it is possible to match, 
starting from a certain selected position of the cutting machine, a 
definite nominal profile with consideration of the swivelling angle of the 
cutting machine. 
There have become known cutting machines of the initially mentioned type in 
which the loading means can, for the purpose of increasing the stability 
during cutting operation, be lowered below the plane of the travelling 
surfaces of the machine whereby the front end of the machine is lifted. 
With such devices, the display means would be responsible for erroneously 
controlling the cutting tools if any change of the position of the cutting 
machine, in particular any lifting of the cutting machine at its front 
end, would not additionally be taken in consideration. 
The invention now aims at providing a simple device of the initially 
mentioned type, with which erroneous positions resulting when lifting the 
front part of the machine by a loading means can be compensated and with 
which the predetermined nominal profile can reliably be matched during 
cutting operation. For solving this task, the invention essentially 
consists in that an angular position transmitter is provided for 
transmitting the position of the loading means or of a part connected 
therewith, relative to the frame of the cutting machine, the signals of 
said transmitter being transmitted to an evaluating circuit, in particular 
a computing device, for correcting the display of the height position of 
the cutting tool or for controlling this height position with 
consideration of the machine geometry. On account of an angular position 
transmitter transmitting the position of the loading means relative to the 
frame of the cutting machine being provided, the extent of adjustment of 
the frame of the cutting machine can be determined with consideration of 
the geometry of the linking arrangement of the loading ramp to the frame 
and of the cutting arm to the machine, and the display means and the 
control of the position of the cutting tool can correspondingly be 
corrected. 
In a particularly simple manner, the arrangement is, according to the 
invention, such that the angular position transmitter is formed of an 
angle measuring device, in particular an angle coding means or 
inclinometer connected with the operating cylinder of the loading means or 
with the frame or with the loading means at its pivotal axis for 
swivelling same relative to the frame. 
In particular when using electric or electronic display means or control 
means, respectively, the evaluating circuit preferably comprises a memory 
in which is stored, in correspondence with the machine geometry, the 
mathematical relationship of the angle of the loading means to the frame 
to the needed angular correction of the cutting arm. Consideration of the 
machine geometry is, in this case, necessary in particular because the 
linking axis of the loading ramp is, as a rule, different from the linking 
axis of the cutting arm and thus a certain angle of inclination of the 
loading ramp relative to the frame results in a deviating angle, being 
different from said angle, in the position of the cutting arm if the frame 
of the cutting machine is lifted. In this case, the evaluating circuit 
preferably comprises at least one comparator which transmits, after having 
adjusted a predetermined angle between frame and loading means, the signal 
of the angular position transmitter or the corresponding corrective signal 
for the angle of elevation of the cutting tool, respectively, to the 
control means of the cutting arm or to the display means.

In FIG. 1, the frame of the cutting machine is designated by 1. The cutting 
machine has crawlers 2 by means of which the cutting machine can be moved 
within the drift cross section. A traversing gear is supported on a tower 
for rotation around a substantially vertical axis 3 and a cutting arm 5 is 
pivotally linked to the traversing gear so as to be swivelable around a 
substantially horizontal axis 4. The cutting arm 5 carries cutting heads 6 
by means of which can be cut the rock to be excavated. A loading means 7 
can be swivelled on the frame 1 of the cutting machine around a 
substantially horizontal axis 8, an operating cylinder 9 being pivotally 
linked to the frame 1 at 10 for swivelling the loading ramp 7. In the 
representation of FIG. 1, the cutting machine assumes a position in which 
the loading ramp is not lowered below the running surface 11 of the 
crawlers 2. In the shown position of the cutting head 6, in which the 
cutting head contacts the floor of the drift, the cutting arm 5 is 
swivelled for an angle .alpha..sub.o relative to the traversing gear. The 
straight line connecting the linking axis 8 with the tip 12 of the loading 
ramp 7 includes an angle .gamma..sub.o with the running surface 11 of the 
crawlers. The operating cylinder 9 of the loading ramp 7 includes an angle 
.delta..sub.o with a horizontal plane 13. In the representation of FIG. 2, 
the operating cylinder 9 is pressurized by pressurized fluid, so that the 
loading ramp 7 is moved below the running surface 11 of the crawler 
chassis. The front end of the machine and thus the running surface 11 is 
thus swivelled for an angle .epsilon. with respect to the point 14 or 
rotation located at the rear area of the crawler chasis, the angle between 
the plane 13 and the operating cylinder now assuming the value .theta.. 
Without any correction of the angle .alpha..sub.o for the swivelled 
position of the cutting arm 5, there would, in this case, result lifting 
of the cutting head for a distance a and thus a mal-position relative to 
the nominal profile. The point 15 of the cutting head 6 originally 
contacting the floor is thus lifted for this distance a, this lifting 
distance a being proportional to sin .epsilon.. The connecting line 
between the linking axis 8 and the tip 12 of the loading means 7 includes 
now an angle .gamma.=.gamma..sub.o +.DELTA..gamma. with the running 
surface 11. 
In this case, there apply the following equations 
EQU a=14, 15.multidot.sin .epsilon. 
EQU a=14, 15.multidot.sin k.sub.1 .DELTA..gamma. 
EQU a=14, 15.multidot.sin k.sub.2 .DELTA..theta. 
EQU .epsilon.=k.sub.1 .DELTA..gamma.=k.sub.2 .DELTA..theta. 
EQU .theta.=.theta..sub.o +.DELTA..theta. 
From these equations, in which 14, 15 means the distance between the points 
14 and 15, it can clearly be derived, that a number of coefficients of 
proportionality typical for the machine, in particular k.sub.1 and 
k.sub.2, must be considered for reliably obtaining the correct position of 
the cutting head, i.e. a descending movement of the head 6 in direction to 
the floor for the distance a. The required corrective angle .DELTA..alpha. 
can be taken from FIG. 3, in which the mal-position of the cutting head 6 
is shown in dashed lines and the correct position relative to the nominal 
profile to be established is shown in full lines. 
The angular position transmitter required for detecting the erroneous 
position or mal-position can act either on the swivelling axis 8 or on the 
swivelling axis 10 and is schematically indicated in FIG. 3 by 16 and 17. 
The angular position transmitter 16 can measure the angle .gamma. relative 
to the frame 1 of the machine, whereas the angular position transmitter 17 
can measure the angle .theta. relative to the horizontal plane 13. The 
transmitter 16, 17 is connected to an evaluating circuit 18 which is 
connected to a display 19 of the height position of the cutting tool.