A method and a device for establishing mounting holes in the ground, in particular for markers in roads.
The present invention relates to a method of establishing or providing accurately oriented mounting holes in the ground, preferably in hard surfaces, such as holes in roads and streets for receiving subterranean fixpoint markers, the method being of the kind defined in the introductory clause of claim 1.
As already stated in WO/83/03134 it may hereby be essential that rod shaped markers are mounted with an accurate vertical axis orientation, whereby it should be aspired at that also the mounting holes are performed in a vertical orientation. According to said publication the holes may be easily performed by means of a drill or a chisel being guided downwards along a vertically projecting guide frame which for an easy transport may be disposed on a suitable vehicle, and for achieving a vertical hole formation it will of course be possible to adjust the guide frame to a vertical position by use of a suitable multiple direction adjustable connection between the guide frame and the vehicle, so that the frame is in vertical position although the vehicle is supported in a position which is or inclined lengthwards and/or si dewards.
In practice, however, there are several problems attached to the use of such an arrangement. Firstly because an employed vehicle normally will be spring suspended so that its chassis and thereby the guiding frame may alter its position or orientation by occur ing external influence.
However, it is well known that a vehicle chassis in a working position may be stabilized by means of downwards displaceable supporting legs, and so far the stability problems indicated mightthus be solved.
By the present invention, however, it is realized that it is v e ry advantageous to employ a three-point support where the one point is constituted by a base or foot portion of the guide frame per se, whereas the two other points a re consistuted by as well mutually as - with respect to the guide frame - opposedly arranged, downwardly movable supporting legs on the chassis. Thereby is obtained firstly that the two supporting legs by an individual lowering may determine the angular position of the chassis and thereby the angular position of the guide frame in one main direction without involving the use of further devices for adjusting the angle of the guide frame in this direction, and secondly that the base or foot portion of the guide frame will be urged against the ground with high force in so far as this foot portion is going to support the total weight of the guide frame and the tool attached thereto together with a great deal of the weight of the chassis and the devices supported thereby. In particular by formations of holes in solid surfaces, such as asphalt, it is an essential advantage that the base or foot portion of the guide frame is pressed firmly against the surface in order to avoid a local raise of the surface material around the hole thus formed. The angular position of the guide frame in the second main direction may hereby in principle also be dependent on the position of the two supporting legs, but the guide frame may, besides, easily be arranged angularly adjustable with respect to the chassis in the direction in question. The invention which on this background has been defined in the claims and which in excess of a method also comprises a device for carrying out the method, will now be explained in more detail with reference to the accompanying drawings, in which:
Fig. 1 is a perspective view of a device according to the invention, Fig. 2 is a side view of the device, Fig. 3 is a plan view thereof, and Fig. 4 is a cross sectional view for illustrating the mounting of a marker in a hole produced in accordance with the method.
The device shown consists of a chassis plate 2 supported by an undercarriage with support wheels 4 and draw bar 6 and at each corner being provided with a hydraulicaIly operated supporting leg, referred to as 8, 10, 12, and 14, respectively. At the rear end of the chassis plate 2 (left in the drawings) an upright guide frame 16 is arranged for vertical guiding of a tool head 18, preferably in the form of a socalled hydraulicaIly operated hammer, into which a downwardly projecting chisel rod 20 is secured and which is provided with weight blocks 22. By a strong hinge 24 the guide frame 16 is pivotably connected to a holding bar 26 which is displaceable on the chassis plate 2, which bar 26 extends forwardly towards the front end of the plate 2, where it is rigidly connected to one end of a hydraulic cylinder 28, the other end of which is pivotably connected to a vertical trunnion or pin 30 on the plate 2. The holding bar 26 projects outwardly to the guide frame 16 through a transverse guiding slot 32 below a transverse beam 34 which prevents the holding bar 26 from rotating around its longitudinal axis but allows said bar 26 to be displaced in its longitudinal as well as in its transverse direction. A longitudinal displacement may be caused by means of the cylinder 28 and a transverse displacement or transverse sweep may be caused by a transversely positioned cylinder 36 being inserted between a side of the holding bar 26 and a trunnion bracket 38 at the outer edge
of the plate 2, while the holding bar thereby may be pivoted around the pin 30.
By means of an inclined working cylinder 40 the guide frame 16 is connected to the front end of the holding bar 26 in such a way that the guide frame thereby may be stabilized in its upright position, and as shown in dotted lines in Fig. 2 it may be lowered over the chassis plate 2.
At its lowermost end the guide frame 16 comprises a foot plate 42 having a passage. hole 44 for the chisel rod 20. Inside the guide frame a working cylinder 46 resting on the foot plate 18 is arranged, the piston rod 48 of this cylinder extending upwardly through a passage in the tool head 18 and at the top being in a loose supporting engagement with a supporting portion 50 on the tool head. The mentioned passage is sufficiently sized for the tool head to be lowered completely down over the cylinder 46.
On the chassis plate 2 are arranged a hydraulic power station 52 and a control board 54 for controlling the various work cylinders, and on the guide frame 16 is arranged a clinometer or bubble double level 56 for showing the desired working direction of the guide frame, this direction preferably being exactly vertical.
The length of the lower end portion 58 of the guide frame between the hinge 24 and the foot plate 42 is considerably longer than the distance of the hinge above the ground when the supporting legs 8-14 are lifted for enabling free transport of the device on the wheels 4; this means, of course, that the device is only mobile when the guide frame is suitably laid down, cf. Fig. 2, whereby the lowermost portion 58 is correspondingly lifted above the ground.
The device is used in the following way: By means of a traction vehicle the device is positioned at the
desired place for performing a mounting hole in the ground or the road. All four supporting legs 8-14 are activated for lifting the chassis plate 2 with or without the underlying undercarriage. The rear supporting legs 12 and 14 are sufficiently lowered for the hinge 24 to be brought to such a level which enables a free pivoting down of the lower end portion 58 of the guide frame 16. Then the guide frame 16 is raised by activating the work cylinder 40, whereupon the supporting legs 12 and 14 are lifted until the foot plate 42 rests on the ground surface. If necessary it should be controlled that the mounting hole forming location defined by the foot plate hole 44 is exactly the desired location, and whether there are obstructions to the hole forming on the place in question, e.g. in the form of a detectable underlying cable in the ground, whereby it may be desired to move the hole forming location just a short distance. Such displacement or moving may be caused by activation of the work cylinders 28 and 36, i.e. without moving the device per se, seeing that these work cylinders - preferably during an intermediate lifting of the foot plate 42 from the road surface by lowering the supporting legs 12 and 14 - may be activated for determining any position of the foot plate hole 44 inside the area A shown in Fig. 3. When hereby the final hole forming location has been determined, i.e. when the foot plate 42 rests on the road surface on the desired spot inside the area A, the supporting legs 12 and 14 are drawn completely off the road surface, and after a previous rough adjustment the following two exact adjustments are carried out:
1) The supporting legs 8 and 10 or one of these are activated until the transverse direction of the chassis plate 2 is horizontal which can be read from the level 56 in Fig. 1, while the guide frame 16 is thereby guided to
a vertical position in one vertical main plane. 2) The cylinder 40 is activated for tilting the guide frame 16 in the second vertical main plane until the desired vertical position is read from the double bubble level 56. Thereupon the guide frame 16 will be in a vertical position on the desired location, and it will be clear that the foot plate 42 with the lifted supporting legs 12 and 14 will exert a considerable pressure upon the road surface, as the weight of the device is not carried by the support wheels 4.
Subsequently, the hole forming operation can start and the operation is initiated by activating the work cylinder 46 for lowering the tool head 18 until the lower end of the chisel rod 20 through the foot plate hole rests on the road surface, whereafter the piston rod 48 is further lowered for enabling a subsequent quick and - as to the driving force - well defined driving down of the tool head during descendence of the chisel rod 20 in the ground. The tool head or the hydraulic powered hammer 18 is then activated for vibrating down the chisel rod 20, and thereby it is important that the tool head is well weightloaded and therefore the shown weight blocks 22 are used. For the hole performance per se it is also important that a massive chisel rod 20 is used, seeing that such a rod by the descendence w i l l cause a wedge effect whereby the material displaced partly will be radially compacted, so that the hole formed will appear with a hard wall facilitating a subsequent guiding down in the hole of a marker rod, the diameter of which is just a little smaller than that of the mounting hole. In other words, hereby a hole diameter which is just a little larger than that of the marker rod will be sufficient, and such minimized hole diameter will result in a minimized necessary force
of pressure for the tool head 18, and a maximized performance speed for the mounting hole, respectively.
After the descendence of the chisel rod in the ground, e.g. to a depth of 0.5-2 m, a considerable force is required for pulling up the chisel rod, but such force may be immediately delivered by the working c y l i n d e r 46 which may be activated for pulling up the tool head 18 until the lower end of the chisel rod is clear of the ground. Thereupon the device may be removed from the mounting location when the supporting legs 8 and 10 have been pulled up and the guide frame 16 has been laid down to its position shown in Fig. 2, whereafter the hole performed is freely accessible for mounting of a marker rod therein. This mounting may preferably take place by the marker rod 56 as shown in Fig. 4 being brought into a holding engagement with the lower end of a mounting rod 58, by means of which the marker is lowered to the bottom of the hole; the upper end of the mounting rod is provided with a clinometer or bubble level 60 which may indicate an exactly vertical position of the rod and consequently of the marker rod. With the mounting rod fixed in this position a small quantity of a stabilizing material, such as gravel and water, is poured into the hole, whereby the position of the marker rod in the hole is directionally stabilized. Thereafter the holding engagement with the marker is released by operating a control lever 62 at the upper end of the mounting rod 58 which is then pulled up from the hole whereafter the hole is filled with a suitable filler material. In practice it will be preferred that the tool head with its appurtenant additional weight load being fully pulled up on the guide frame is located in such high position that its centre of gravity in the laid down transportation position of the guide frame as shown in Fig. 2
is positioned in a zone directly above the pairs of support wheels 4, whereby the device may show up a good driving stability.
It is i m po r t a n t that the foot plate 42 during the production of the hole rests on the ground with a great weight or pressure, as otherwise the ground by the occurring material displacement may move upwardly and form a bulge which, of course, will be bothering in a roadway. Finally, it should be noted that the foot plate 42 may be angularly displaceably connected to the guide frame 16, e.g. through a ball and socket joint, so that the foot plate may be in a plane contact with the ground surface, although the guide frame in its vertical position forms a more or less distinctive and from 90 differing angle with the ground. Besides, it will be within the scope of the invention to arrange the guide frame in a stationary upright position in relation to the vehicle and the frame being compulsorily displaceable, in its longitudinal direction, so that the frame per se forms a downwardly displaceable supporting leg. Thereby the supporting legs 12 and 14 may be omitted.