ROTARY DRILLING TOOL WITH AN EXPANSIBLE REAMER

Abstract: The invention relates to a simplified and reliably functioning drill tool for a sinker drill for drilling in loose earth, such as when rein­ forcing the foundations in connection with building. The drill tool according to the present invention is in two parts and consists of an upper cylindrical transition piece (1), its central axis coinciding with the rotary axis of the drill tool, and provided with an eccentric, cylin­ drical hole (4), and of a lower reamer piece (2) provided with an up­ wardly directed shaft (3) to fit into the hole. In operating position the shaft (3) is fully inserted into the hole (4) and the transition piece (1) and reamer piece (2) cooperate. In extraction position the shaft (3) is partially withdrawn from the hole (4) to permit the drill (1,2) to be drawn up through a casing-tube.

Description: The present invention relates to a drill with reamer piece for a sinker drill. Such drills are carried by a drill rod and accompanied by a casing-tube down into the drill hole. Drill cutting chippings are removed by flushing medium supplied to the drill through a channel in the drill rod. The drill is influenced by a hammer and also by rotation through the drill rod. There are many designs of drills of this type for boring in both solid and loose ground. When reinforcing the foundations for building purposes, the intention is that the ground shall not shift, so as to avoid cracks occuring in the buildings. When drilling with sinker drills this can be achieved by using a casing-tube to grout concrete pillars, at the same time filling any ground fissures with concrete. The ground surface can also be prepared by laying a horizontal surface to avoid displacements in the reinforcements. In GB-A-2 031 481 there is described a rotary drill where a transition piece has an axial hole which is eccentric in relation to the transition piece. The reaming piece has a shaft which is inserted in the eccentric hole. The reaming piece can through a turning movement be placed either in a swung out position, which is an operating position, or in a withdrawn position. The object with the present invention is in relation to said GB-A-2 031 481 to create better stops for the turning movements of the reaming piece and then especially a better stop at the operating position. This is obtained by using a cylindrical body which is formed by two segments from the transition piece and the reaming piece. One segment is included in the transmission piece and beside the hole. The other segment is included in the reaming piece. The shaft for the hole is arranged at the other segment. Through the shaft it is possible to move the reaming piece axially and to turn it. Are the two segments arranged after each other it is possible to bring the reaming piece in a withdrawn position. Are the two segments constituting a cylindrical body is the reaming piece in an operating position. One embodiement of the invention will be described below by way of example, with reference to the accompanying drawings in which Fig 1 shows a drill according to the invention, Fig 2A and 2B show a reamer piece according to the invention, Fig 3A and 3B show a transition piece according to the invention, Fig 4 shows the drill in operating position, Fig 5 shows the drill in swung-in position, and Fig 6 shows the drill in extraction position. The drill comprises a cylindrical transition piece 1 and a reamer piece 2 provided with hard metal cutting edges or pins arranged in substantially one plane. The transition piece 1 is secured in any suitable manner to a drill rod (not shown). The central axis of the transition piece coincides with the axis of rotation of the drill rod. An eccentric hole 4 is provided at the flat lower side of the transition piece 1, as well as a shoulder 6 having an inwardly facing flat, axial surface 8 made in one piece with the rest of the transition piece. In a plane opposite the hard metal cutting edges, the reamer piece 2 is provided with an eccentric shaft 3 for insertion into the hole 4. The axial length of the shaft 3 corresponds to the axial depth of the hole 4. The surface of the reamer piece 2 has an outwardly directed shoulder 5 cooperating with the shoulder 6 on the transition piece during drilling. The surface 8 of the transition piece also cooperates with a surface 7 on the reamer piece, this latter surface extending axially from the shoulder 5 to the plane in which the shaft 3 is arranged. The shaft 3 is provided with a narrowed waist 10, the axial depth thereof substantially corresponding to or slightly exceeding the axial length of the shoulder 6. Along part of the surface of the shaft, the waist 10 is provided with an upward extension 11 towards the free end of the shaft, thus forming a shoulder 14 at the transition between waist extension 11 and shaft surface. Figure 4 shows the drill in operating position A. The free end of the shaft 3 is in contact with the bottom of the hole 4 in transition piece 1. The shoulders 5 and 6 of the reamer piece 2 and transition piece 1 also cooperate and a flat edge 15 on the lower end of transition piece 1 is in contact with a flat peripheral edge 16 on the upper end of the reamer piece 2. A pin 13 is inserted through an aperture in the wall of the transition piece, into the space defined by the narrowed waist 10 and the hole 4. In operating position A the pin moves freely and is not subjected to any stress. In this position the transition piece 1 and reamer piece 2 rotate together at the same speed as the drill rod. The hammer strikes in two planes, i. e. the plane defined by the upper end of the shaft and the bottom of the hole and the plane defined by the flat peripheral edge 15 and the flat peripheral edge 16. The reamer piece is swung out in the usual manner below the casing-tube, not shown. Extraction of the drill bit is shown in Figures 5 and 6, and can now be effected without interrupting or reversing the rotary movement. The drill rod, with the transition piece attached, is raised and when it has been raised a distance corresponding to the axial length of the waist and that of the shoulder 6, the reamer shoulder 5 will be disengaged from the transition-piece shoulder 6. The reamer piece will then rotate to axial alignment with the transition piece and the accompanying casing-tube, not shown, thus permitting the latter to be extracted. In this position the reamer piece is further axially displaced in relation to the transition piece since the pin enters the extension 11 in the waist. This axial displacement continues until the pin is stopped by the shoulder 14. Extraction continues as the pin locks the reamer piece in the hole of the transition piece. The outer diameter of the shaft is preferably somewhat smaller than the diameter of the holder, so that a cylindrical space is formed between shaft and hole. The invention permits the reamer piece to be swung in without alteration of the direction of rotation. Furthermore, the drill can be operated in any desired direction of rotation. Extraction is facilitated by blowing clean the shoulder system. The casing-tube, or an impact shoe provided at the lower end of the casing-tube, also has a storage function during reamer drilling according to the invention.

Claims: A rotary drill comprising a reaming piece (2) and a substantially cylindrical transition piece (1) for a sinker drill, said drill being able to be carried by a drill rod co-axially located in a casing-tube, the reamer piece (2) being swung out below the casing-tube in its operating position and swung in in withdrawn position to enable the drill to be drawn up through the casing-tube, whereby the central axis of the transition piece (1) coincides with the axis of rotation of the drill rod and said transition piece (1) is provided with an eccentric, cylindrical hole (4) at its lower end, the central axis of the hole (4) lying substantially parallel to the axis of rotation of the drill rod, and whereby the reamer piece (2) is provided with a shaft (3) to fit into the cylindrical hole (4), the axial length of the shaft (3) substantially agreeing with the axial depth of the cylindrical hold (4), characterised in that the reaming piece (2) and the transition piece (1) comprise two cylindrical segments able to fit with one another into a cylindrical body where the one is a part of the transition piece (1) and is placed beside the hole (4) and where the other segment is a part of the reaming piece (2) and from which the said shaft (3) emanates, and in that said shaft is movable in an axial direction and turnable in such a way that in a position where the cylindrical body is created by said two segments, the reaming piece (2) is in a swung out position and in a position where the cylindrical segments are situated after each other the reaming piece can be brought in a withdrawn position. A rotary drill according to the preceding claim, characterised in that the shaft (3) is provided with a waist (10), its axial extension being in agreement with the axial length of the cylindrical body and a pin (13) being inserted into the space (12) formed between the defining surface of the hole and the waist (10) of the shaft (3).

Inventors: LOEF, UNO, LÖF, Uno
Applicants: LOEVAB LOEF OCH OESTLUND AB
Application year: 1987
Main classification: E21B10
IPC codes: E21B10