A device for removing debris from a helical drilling tool

Abstract

 A non motor-driven device for clearing debris from a helically-shaped drilling tool (4), comprises a slide (2) freely translating on a vertical guide (1). The slide (2) is secured to a radial scraping blade (6) engaging the helical tool (4). The blade and the helical tool are operatively coupled for mutual motion such to force the blade to run along the scrolls of the helical tool, thereby causing the debris (8) deposited on the helical tool during drilling to fall off.

Description

FIELD OF THE INVENTION

[0001] The present invention pertains to the field of straight-ahead drilling by means of a helical tool. More particularly, the invention refers to a device for clearing the helical drilling tool of debris.

BACKGROUND OF THE INVENTION

[0002] In straight-ahead drilling methods the soil brought up to surface by the helical drilling tool has to be removed to prevent it from falling down a considerable height when lifted up high on the helix.

[0003] At present there are known several kinds of debris removing devices. Generally, these devices are motor-driven. The most complete type consists of a slide slidably mounted on the drilling tower and secured to a guiding ring that surrounds a length of the helical tool in order to keep it at the right distance from the drilling tower. The active part of the clearing device is comprised of a rotating portion mounted to said ring. Such rotating portion comprises a scraping blade inserted between the scrolls of the helical tool and rotated by a motor through a toothed gearing assembly.

[0004] In operation, the clearing device rotates the scraping blade down the scrolls forcing the debris to fall, regardless of whether the helical tool is stationary or rotating. If the device is not activated, it tends to ascend the helical tool when this rotates in the drilling direction.

[0005] A first inconvenience with this kind of clearing device is concerned with vertical movement along the helical tool. The clearing device must be stopped from running up the helical tool and interfering with the driving unit fitted at the top of the helical drilling tool. Also, the clearing device must be prevented from descending too far, as it could get stuck in the ground. Therefore, the clearing device motion has to be controlled by an operator or a special automatic control unit.

[0006] Another prior art drawback concerns the maximum transversal size of the helical tool. Generally, the maximum diameter of the tool is limited by the near drilling tower. When a clearing device of this kind is provided, the tower and the clearing device must be spaced apart to fit a rolling bearing, a toothed gearing and a motor housing. It follows that the maximum diameter of helix that can be cleared is considerably less than the maximum diameter of helix that could be fitted in the absence of a clearing device.

[0007] Finally, the provision of a motor and toothed gearing besides involving implementation expenses, causes practical complications due to the presence of cumbersome and hindering electric cables or hydraulic lines.

SUMMARY OF THE INVENTION

[0008] An object of the present invention is to provide a device allowing the expensive driving means of conventional clearing devices to be dispensed with and which is free of the above discussed inconveniences.

[0009] A further object of the invention is to provide a device capable of relieving the operator of the task of continuously having to pay attention to the position of the clearing device, without incurring further expenses for a separate special control system.

[0010] These and further objects which will be more apparent hereinafter are attained according to the present invention by the provision of a non motor-driven device for clearing debris from a helically-shaped drilling tool, comprising a slide capable of translating freely in a direction parallel to the axis of said tool, said slide being secured in said translating motion to a scraping member engaging the helical tool, said scraping member and said helical tool being operatively coupled for mutual motion such to force said scraping member to run along the scrolls of the helical tool, thereby causing the debris deposited on the helical tool during drilling to fall off.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a better understanding of the present invention, reference is made to the following detailed description of two preferred but not limiting embodiments considered in combination with the accompanying drawings in which:

FIG. 1

depicts schematically a first embodiment of a debris clearing device arranged in accordance with the present invention; and

FIG. 2

schematically shows a second embodiment of the device of this invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0012] With reference initially to FIG. 1, numeral 1 schematically designates the position of a pair of vertical guides fixed to the drilling tower (not shown) which exploits a conventional helical drilling tool 4.

[0013] In brief, the device for removing debris is composed of a first non rotating portion vertically slidable along the guides and the helical tool, and a second rotatable portion mounted to the first portion but free to rotate about the central drilling axis x of the tool.

[0014] The non rotating part of the clearing device comprises a slide 2 slidably mounted on guides 1 and a cylindrical member 3 for guiding the helical drilling tool 4. Cylindrical member 3 is inserted on the helical tool and rigidly fixed to slide 2.

[0015] Cylindrical member 3 is fitted with a coaxial bearing the rotating race 5 of which is secured to a scraping member 6, preferably in form of a blade. As shown, scraping member 6 provides a surface disposed substantially radially on helical tool 4 and adapted to make the debris 8 which has deposited on the scrolls of the tool during drilling move and fall off.

[0016] In the example of FIG. 1, the upper, outer portion 6a of scraping member 6 is secured to the rotating part of the bearing 5. The base 6b of the blade member skims the surface of the helical tool. The radially inner end portion of the blade base rests on the helical tool by means of a roller means 7.

[0017] In operation, as the helical tool is screwed into the ground, the rotating portion of the clearing device rotated freely following rotation of the helical tool through scraping member 6. At the end of the screwing step, the debris clearing device is located up at top of the helical tool, just above the drilling surface. The drilling tool is then raised up, thereby tearing the ground comprised between it scrolls and creating a bore (not shown) in the ground.

[0018] During the raising step, debris resting on the helical tool exerts a contrasting action against the scraping member 6 which tends to urge the clearing device upwardly sliding along vertical guides 1. Simultaneously, the clearing device descends for gravity along the helical tool which is withdrawn up and out of the bore full of debris 8. In this phase, the scraping member 6 is forced to rotate over the scrolls of the helical tool in the direction of the lower end of the helix. In doing so, scraping member 6 causes the fall out of the debris which remained on the helical tool at the end of the drilling step. The non-rotating portion of the clearing device rests on the rotating portion, which in turn rests on the helical tool by means of roller 7. Roller 7 rolls on the inclined plane of the helix. Downward motion of the clearing device along the helix is facilitated because of roller 7 resting on the steepest, radially innermost part of the helix.

[0019] With reference to FIG. 2, in an alternative embodiment of the present invention an end portion of a swivel arm 10 is pivotally mounted to the slide 2. Swivel arm 10 is pivotal in a substantially horizontal plane. The other end of swivel arm 10, substantially tangent to the edge of the helix, carries a clearing scraping blade 6. As discussed for the embodiment of FIG. 1, the innermost part of the blade, i.e. nearest to the core or shaft of the helical tool, rests thereon by means of a end roller member 7 acting on the steepest part of the helix scrolls.

[0020] Swivel arm 10 is provided with an actuator means such as a cylinder 11 having its end mounted to slide 2 and arm 10. The cylinder serves to move the blade 6 to and from its operation position of FIG. 2, in which the blade engages the helical tool and a rest position (not shown) away from the helix.

[0021] Regarding operation of this second embodiment of the invention, the clearing device is disengaged from the helical tool as this is screwed into the ground. The clearing device is in a passive position at the bottom of vertical guides 1 on the ground surface.

[0022] At the end of the screwing-in phase, cylinder 11 is operated to move swivel arm 10 with scraping blade 6 in its active position oriented radially on the helix scrolls. The helical tool is then withdrawn upwards. In the illustrated operation configuration, slide 2 is forced to translate vertically with scraping member 6, whereby the whole clearing device is raised to the top of the vertical guides.

[0023] As shown in FIG. 2, the helical tool full of debris is then rotated in the direction of rotation opposite to that of drilling. Rotation of the helical tool forces the clearing device to slide down the vertical guides. During descent, the scraping member 6 runs along the scrolls and causes the debris to fall off the helical tool, clearing it.

Claims

1. A non motor-driven device for clearing debris from a helically-shaped drilling tool (4), comprising a slide (2) capable of translating freely in a direction parallel to the axis (x) of said tool (4), said slide (2) being secured in said translating motion to a scraping member (6) engaging the helical tool (4), said scraping member and said helical tool being operatively coupled for mutual motion such to force said scraping member to run along the scrolls of the helical tool, thereby causing the debris (8) deposited on the helical tool during drilling to fall off.

2. A device as claimed in claim 1, characterised in that the scraping means (6) is oriented substantially radially on the helical tool (4).

3. A device as claimed in claim 1, characterised in that the scraping means (6) rests on the scrolls of the helical tool (4) through a roller means (7).

4. A device as claimed in claim 3, characterised in that the roller means (7) rests on the scrolls proximate to the central core of the helical tool.

5. A device as claimed in claim 1, characterised in that the scraping member (6) is supported by the slide (2) in pivotal manner about said central axis (x) of the helical tool.

6. A device as claimed in claim 5, characterised in that the scraping member (6) is pivotally mounted to a cylindrical member (3) for guiding the helical tool, said cylindrical member being rigidly fixed to the slide (2).

7. A device as claimed in claim 1, characterised in that the scraping means (6) is pivotal about an axis substantially parallel to said central axis (x), the scraping member having an active position engaging the helical tool and a passive or rest position external to said tool.

8. A device as claimed in claim 1, characterised in that the scraping means (6) is mounted to an end of a swivel arm (10) having the other end pivotally mounted to the slide (2) about an axis substantially parallel to said central axis (x), said swivel arm (10) being pivotally movable between an active position substantially tangent to the helical tool and a passive position external to said tool.

9. A device as claimed in claim 8, characterised in that said arm (10) is movable by means of a cylinder actuator means (11) fixed to the arm (10) and the slide (2).

Drawing