FOUNDATION DRILLING MACHINE WITH BRAKING SYSTEM.

The present patent application for industrial invention relates to a foundation drilling machine, such as for example a drill or a bucket, provided with braking system in order to prevent a base from rotating with respect to the undercarriage.

Although the following description refers to drilling machines, the present invention is extended to all foundation drilling machines, wherein a base rotates with respect to an undercarriage.

Amongst foundation drilling machines, drills are known that are intended to drill holes into the ground for piling.

With reference to Fig. 1 , a drilling machine defined as "drilling machine with telescopic bars" is described for illustrative purposes and is indicated with reference numeral (200).

The drilling machine (200) comprises a base (1 ) revolvingly mounted on an undercarriage (2) that is generally provided with tracks (20). A mast (3) is connected to the base (1 ) by means of an articulated system (4). A telescopic bars unit, defined as kelly bar (5), is supported by a cable (60) that passes above the mast (3). The kelly bar (5) is provided with a tool (50) intended to drill holes (F) into the ground. A rotation device, defined as rotary (51 ), drives into rotation the kelly bar (5) that supports the tool (50) during drilling. The kelly bar (5) is connected by means of the cable (60) to a winch (6) which is mounted in the mast (3).

The dimensions and the weight of the base (1 ) of the drilling machine depend on the depth and the diameter of the hole (F) to be drilled by the tool (50). The depth of the hole (F) determines the length of the kelly bar (5), that is to say the length of the set of telescopic bars used to transmit the thrust and the torque to the tool (5). For an acceptable productivity, the maximum diameter of the hole (F) is strictly related to the torque that is transmitted to the tool (50) by the rotary (51 ) through the bars (5). The torsional moment applied on the kelly bar (5) in order to rotate the tool (50) determines the section of the telescopic bars of the kelly bar.

In case of a heavy kelly bar and a large tool, the mast (3) and the articulated system (4) used to connect the mast to the base must be very strong and the winch (6) must have a high pull.

The winch (6) is used to bring the kelly bar and the tool (50) filled with soil back to the ground level. Both the weight of the kelly bar and the weight of the tool, which is filled with material, are applied on the winch.

For this reason, if the hole (F) to be drilled has a large diameter and a high depth, the base (1 ) must have large dimensions in order to guarantee a suitable stability of the drilling machine when the winch is pulling, and to oppose the torque applied to the tool (50) during drilling.

A base with lower dimensions could be used only in the case of a low depth and a large diameter of the hole. In such a case, the kelly bar is lighter and therefore a lower extraction force is needed to lift it.

Moreover, in case of a lower depth, shorter kelly bars can be used; accordingly, the mast can be shorter and the undercarriage can be smaller to guarantee the same stability with a lowered center of gravity.

However, the machines that are used to drill holes with a large diameter and a low depth are impaired by a technical problem because they need to oppose a high torque with a small base.

The base (1 ) of the drills, such as excavators or cranes, rotates around a vertical axis (Y) with respect to the undercarriage (2). Such a rotation is permitted by a rotation system (7) mounted between the base (1 ) and the undercarriage (2).

With reference to Fig. 2, the rotation system (7) comprises a fifth wheel (70) integral with the undercarriage (2). The fifth wheel (70) is a toothed crown provided with internal toothing (71 ) or external toothing.

A pinion (72) engages in the internal toothing (71 ) of the fifth wheel. The pinion (72) is actuated by an epicycloid reduction gear (73) integral with the base (1 ). A hydraulic motor (74) of piston type actuates the epicycloid reduction gear (73).

Only two braking systems are available in these machines:

a) A hydraulic system that allows the base (1 ) to slow down and stop its rotation by means of valves acting on the hydraulic motor (74) (the oil is bypassed from one branch to the other branch by means of maximum valves).

b) A negative lamellar brake with sintered discs and clutches joined by springs and separated by hydraulic pressure, when not braking; such a brake is positioned in the hydraulic motor (74) or in the epicycloid reduction gear (73).

The base (1 ) must not rotate during the drilling operation. The torque generated on the tool is opposed by the negative lamellar brake.

It is not easy to increase such a braking capacity to allow for using a higher torque.

If a manufacturer intends to build the entire machine on his own, in order to increase the braking capacity, he should increase the toothed portion of the fifth wheel (70) or the dimensions or number of the teeth, consequently increasing the class of the epicycloid reduction gear (73) and of the hydraulic motor (74). Alternatively, two or more rotation units can be used. These solutions are complicated in terms of volume and are in any case very expensive.

On the contrary, if the manufacturer intends to use the base of an excavator or a crane that is already available on the market - being this the most common case - it is practically impossible to increase the dimensions or the number of the teeth of the fifth wheel or replace the existing braking unit, that is to say the hydraulic motor assembly, the reduction gear, the pinion and the crown of the fifth wheel.

Another way to prevent the involuntary rotation of the base is to mechanically block the base using for example a foot (30) or stabilizers disposed between the ground and the mast (3). The foot (30) is a structural part actuated by a cylinder and used to stabilize the drilling machine when working with high projections, i.e. when the tool (50) is far away from the base (1 ).

If the foot (30) was to be used also to balance the torque on the tool (50), during the rotation of the tool, the foot would be converted from a structure that works under compression into a cantilever beam loaded with a bending moment. Therefore the foot (30) would be stronger and consequently heavier. Moreover, also the ground resting surface of the foot should be modified. In fact, such a ground resting surface should be larger and provided with projections able to "grab" into the ground.

Fig. 3 shows a situation in which a larger tool (150) intended to work under the mast (3) is mounted on the machine (200). Obviously, in such a case the tool (150) would interfere with the foot and therefore the foot could not be used to block the drilling machine.

The most important manufacturers usually identify drills by using a number that represents the maximum torque that can be transferred by the machine to the drilling tool (for example Bauer BG18 is a machine with a maximum torque of 18 tons by meter, IMT 220 has a maximum torque of 220 kilo Newton per meter). Some manufacturers additionally use a number that refers to the weight of the machine (for example, Soilmec 618 has a weight of 60 tons and a torque of 18 ton m). In any case, until now, all drills in this category can reach a depth from 30 to 60 meters with maximum torque. Machines with a higher torque are heavier.

So far, large drills have been used to drill holes with a large diameter and a limited depth, being possibly adjusted with lower heights.

Lighter machines could be theoretically used when it is not necessary to reach a high depth, with the following advantages:

- a lower cost because of the lower weight of the machine;

- a lower cost and a shorter time to transport the machine;

- a lower cost for transportation permissions. EP2672014 discloses a method and a system for controlling the movement of a mast in a drilling machine, in particular for obtaining piles.

The purpose of the present invention is to eliminate the drawbacks of the prior art by disclosing a foundation drilling machine that is capable of preventing the involuntary rotations of the base with respect to the undercarriage during the drilling operations.

Another purpose of the present invention is to disclose such a foundation drilling machine that is provided with a braking system in order to brake the rotation of the base with respect to the undercarriage, which is versatile, reliable, inexpensive and simple to make and install.

These purposes are achieved according to the present invention with the characteristics of the independent claim 1 .

Advantageous embodiments of the invention appear from the dependent claims.

The foundation drilling machine of the invention comprises:

- a base revolvingly mounted on an undercarriage,

- a rotation system that allows the base to rotate with respect to the undercarriage,

- a tool used to remove the material,

- an articulated system used to connect the tool to the base, and

- a braking system used to block the rotation of the base with respect to the undercarriage during operation.

The braking system comprises:

- a disc unit fixed to the undercarriage, and

- a caliper unit fixed to the base and intended to tighten the disc unit in such a way to block the rotation of the base with respect to the undercarriage.

The advantages of the foundation drilling machine according to the invention are evident. In fact, the braking system allows for using small bases, such as the ones of excavators, preventing the base from rotating with respect to the undercarriage during operation.

Additional features of the invention will be clearer from the detailed description below, which refers to a merely illustrative, not limiting embodiment, as illustrated in the attached figures, wherein:

Fig. 1 is a side view of a drilling machine of the prior art;

Fig. 2 is an axial view of a rotation system of the machinery of Fig. 1 , which allows the base to rotate with respect to the undercarriage;

Fig. 3 is a side view of the machine of Fig. 1 with a larger tool;

Fig. 4 is a side view of the drilling machine according to the invention;

Fig. 5 is a sectional view of the detail contained in circle A of Fig. 4, where the jaws of the caliper of the braking system are open; and

Fig. 6 is the same view as Fig. 5, where the jaws of the caliper of the braking system are closed.

In the following description, the parts that are identical or corresponding to the parts of the preceding description are indicated with the same numerals, omitting a detailed description.

With reference to Fig. 4, a drilling machine according to the invention is disclosed, which is generally indicated with reference numeral (100).

The drilling machine (100) has a rotation system (7) that allows the base to rotate with respect to the undercarriage (2). The rotation system (7) is of traditional type and therefore is not explained in detail.

According to the invention, a braking system (B) is added to the rotation system (7) to block the rotation of the base (1 ) with respect to the undercarriage (2).

With reference to Fig. 5, the braking system comprises:

- a disc unit (8) fixed to the undercarriage (2), and - a caliper unit (9) fixed to the base (1 ) and intended to tighten the disc unit (8) in such a way to block the rotation of the base (1 ) with respect to the undercarriage (2).

Evidently, in a fully equivalent way, the disc unit (8) can be fixed to the base (1 ) and the caliper unit (9) can be fixed to the undercarriage (2).

The disc unit (8) is disposed around the fifth wheel (70) of the rotation system (7). The caliper unit (9) is disposed around the disc unit (8).

The disc unit (8) comprises a lower plate (80) disposed between the undercarriage (2) and the fifth wheel (70) of the rotation system. The lower plate (80) has a disc-like shape with a peripheral edge that protrudes outwards with respect to the fifth wheel (70),

A cylinder (81 ) consisting in a calendered pipe is welded by means of welding (W) to the peripheral edge of the lower plate (80). In view of the above, the cylinder (81 ) is disposed around the fifth wheel (70).

It must be noted that the external ring of the fifth wheel (70) is integral with the base (1 ), and therefore rotates with respect to the disc unit (8) integral with the undercarriage (2). Also the caliper (9) is integral with the base (1 ) and therefore rotates with respect to the undercarriage (2).

An upper disc (82) consisting in an annular circular flange is welded by means of welding (W) at an upper end of the cylinder (81 ), in such a way that the upper disc (82) protrudes radially outwards from the cylinder (81 ) in order to engage inside the caliper unit (9).

The caliper unit (9) extends around the upper disc (82). The caliper unit (9) comprises a plurality of lower jaws (90) and a plurality of upper jaws (91 ) intended to tighten the upper disc (2) (see Fig. 6), in such a way to block the rotation of the base (1 ) with respect to the undercarriage (2).

The lower jaws (90) are fixed, whereas the upper jaws (91 ) are mobile. The caliper unit (9) is fixed to the base (1 ) in such a way that it can move along vertical travels. The caliper unit (9) rests on two lateral supports, and is lifted when it is actuated.

Inside the caliper unit (9) there are one or more hydraulic cylinders that actuate the upper jaws (91 ). By sending pressurized oil to the cylinders of the caliper unit, the upper jaws (91 ) go down and come in contact with the upper surface of the upper disc (82). The additional movement of the upper jaws (91 ) causes the vertical lifting of the caliper (9) until the lower jaws (90) reach the lower part of the upper disc (82). In this way, the caliper (9) is blocked in the upper disc (82), in such a way to make the base (1 ), which is mobile, integral with the undercarriage (2), which is fixed, being in contact with the ground. Such a braking system (B) significantly increases the braking capacity of the base, and allows a small base to withstand the high torques applied by the rotary (51 ) on the tool (50).

The addition of such a braking system (B) to the drilling machine (100) does not involve any structural problems for the base (1 ) and the undercarriage (2).

In fact, the base (1 ) is dimensioned to withstand higher loads; for example, reference is made to the ground leveling works made by an excavator with the bucket at a distance of several meters from the axis of rotation of the base.

The undercarriage (2) is not the one of a standard excavator, but it has been especially studied for drilling or lifting machines, and for this reason it is suitably dimensioned to withstand higher loads.

The fact that the undercarriage (2) is not the same as the one mounted on the excavator provides some economic advantages. The undercarriage (2), the fifth wheel (70) and the base (1 ) are produced separately by different manufacturers and are coupled together when the drilling machine is assembled. In this case it is simply necessary to mount the braking system (B) between the fifth wheel (70) and the undercarriage (2) without increasing the assembly time. Numerous variations and modifications can be made to the present embodiment of the invention, which are within the reach of an expert of the field, falling in any case within the scope of the invention.

In addition to drilling machines, the present invention is extended to foundation drilling machines, in which the work of the machine can cause a rotation of the base with respect to the undercarriage.

In particular, the invention can be extended to a foundation drilling machine such as a hydraulic telescopic bucket. In fact, during the first excavation meters, one of the buckets usually "grabs" the ground better than another bucket, thus causing an undesired rotation of the base with respect to the undercarriage.