US3237704A

US3237704A - Impact drilling apparatus with continuous flushing

Info

Publication number: US3237704A
Application number: US23060A
Authority: US
Inventors: Grospas Pierre
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-04-18
Filing date: 1960-04-18
Publication date: 1966-03-01
Anticipated expiration: 1983-03-01
Also published as: FR1238267A; GB911168A; ES257405A1; BE589733A

Description

P- GROSPAS March 1, 1966 IMPACT DRILLING APPARATUS WITH couwmvous FLUSHING Filed April 18, 1960 11 Sheets-Sheet 1 FIG.2

FIG.17

P- GROSPAS March 1, 1966 IMPACT DRILLING APPARATUS WITH CONTINUOUS FLUSHING Filed April 18, 1960 11 Sheets-Sheet 2 March 1, 1966 3,237,704

IMPACT DRILLING APPARATUS WITH commuous FLUSHING P. GROSPAS 11 Sheets-Sheet 5 Filed April 18. 1960 P. GROSPAS March 1, 1966 IMPACT DRILLING APPARATUS WITH CONTINUOUS FLUSHING ll Sheets-Sheet 4 Filed April 18, 1960 FIG] March 1, 1966 p, GROSPAS 3,237,704

IMPACT DRILLING APPARATUS WITH CONTINUOUS FLUSHING Filed April 18, 1960 11 Sheets-Sheet 5 FIG.

P. GROSPAS March 1, 1966 IMPACT DRILLING APPARATUS WITH CONTINUOUS FLUSHING 11 Sheets-Sheet 6 Filed April 18, 1960 March 1, 1966 GRQSPAS 3,237,704

IMPACT DRILLING APPARATUS WITH CONTINUOUS FLUSHING Filed April 18, 1960 11 Sheets-Sheet 7 X J FIG.18 K 5 ET 0 2 :f'38 1.9

March 1, 1966 GRQSPAS 3,237,704

IMPACT DRILLING APPARATUS WITH CONTINUOUS FLUSHING Filed April 18, 1960 11 Sheets-Sheet 9 w MW 7 7////\ iii; 55;:

0 2 n m 9 $7 y Awyy A? 9 P. GROSPAS 11 Sheets-Sheet 10 March 1, 1966 IMPACT DRILLING APPARATUS WITH CONTINUOUS FLUSHING Filed April 18, 1960 J ////V ///m//// M E E 23 Q E A 65? 64v? March 1, 1966 p, GRQSPAS 3,237,704

IMPACT DRILLING APPARATUS WITH CONTINUOUS FLUSHING Filed April 18. 1960 11 Sheets$heet 11 United States Patent 3,237,704 IMPACT DRILLING APPARATUS WITH QGNTINUQUS FLUSHING Pierre Grospas, Le Continental des Moulins, Monte Carlo, Monaco Fiied Apr. 18, 1969, Ser. No. 23,060 Claims priority, application France, Apr. 18, 1959, 792,471 Claims. (Cl. 17592) The present invention relates to impact drilling apparatus incorporating continuous flushing, and has for an object improvements therein.

As is known, drilling of the ground by impact is effected by a tool or boring bit which is reciprocated within the bored hole, striking the ground at the end of the descending path of travel. This boring bit has at its base cutting edges of a shape suitable for the nature of the ground through which it passes. The control of its movement is effected from the surface by means of lifting devices to which it is connected either through a cable or through a set of shafts which may be solid or, alternatively, hollow in the case where it is desired to evacuate the detritus formed during the progress of the boring by causing to circulate in the interior of the shafts a flushing liquid which comprises water or special sludges.

The process of flushing by the circulation of a liquid injected under pressure necessitates keeping the set of hollow shafts fixed to the boring bit and thus excludes the possibility of connection of hollow shafts by means of a slider with the boring bit as is effected in boring apparatus having solid shafts, which however presents the drawback and the necessity to raise the set of shafts in order to effect the flushing of the holes.

Thus, in boring apparatus having hollow shafts and using the circulation of a flushing liquid, the set of shafts participates continuously in the movement of the boring bit, including the impact shock of the latter at the end of the bored hole so that the shafts are submitted to stresses which can damage them.

However, it will be seen that the power of the raising devices installed on the surface must be of a high value since these devices must reciprocate a very heavy assembly formed by the set of shafts and the boring bit, the frequency of this movement necessarily moreover being as large as possible so as to obtain a satisfactory speed of advance.

The present invention, which relates to the aforementioned boring apparatus having hollow shafts and a circulation of a flushing liquid, has for a particular object the removal of the drawbacks referred to above, that is to say it has for an object a boring apparatus which is particularly capable of working with high advancing speeds to ensure a continuous and efiicient flushing of the bored hole, and a construction such that the members that it comprises, and in particular, the set of hollow shafts, are submitted to the minimum stresses and can be operated by lifting devices of reduced power.

To this end, a boring apparatus according to the invention comprises a set of hollow shaft and at least one boring bit slidable along said shafts and is characterized essentially in that it comprises a latching head and means for reciprocating said latching head, said latching head being provided with means for latching the boring bit at the end of the descending travel, and means for freeing the boring bit at the end of the ascending travel.

Such a boring apparatus is thus essentially remarkable in that the set of hollow shafts is in no case submitted to shocks caused by the operation of the boring bit because indeed the latter is freed at a certain height above the bottom of the bored hole and thus descends by itself in free fall or under pressure so as to effect drilling or boring by impact.

Patented Mar. 1, 1956 It thus equally follows from that which has gone before that because the set of hollow shafts does not participate continuously in the movement of the boring bit, the operation of these hollow shafts may be effected at a controlled speed. This has as a result that the set of shafts may be balanced by a counter-weight at the surface which will thus decrease the power necessary for operating them.

It will be understood that the device used for reciprocating the latching head may be of many possible and verying types, the choice of which will be determined in relation to the envisaged destination of the boring apparatus.

This is also applicable to the means which comprise the latching head and which are intended to latch and free the boring bit.

Finally, the boring bit itself may be of many diverse types comprising at its base cutting edges which may be fixed or movable and whose shape is determined in dependence upon the nature of the ground to be bored. It is pointed out that the boring bit utilized may be a bucket or grab boring bit and in this case means are provided to open and close the blades or scoops of the grab.

All of the embodiments of the present invention are intended to be used in conjunction with a flushing system of circulating fluid capable of carrying detritus out of the hole being bored. Any one of the many wellknown systems may be used and, since they form no part of this invention and are fully described in the available literature, they will neither be shown nor described in detail herein.

In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings which show various embodiments thereof by way of example and in which:

FIGURES 1, 2 and 3 show schematically in longitudinal cross section how the essential main members of a boring apparatus according to the invention operate, these members being shown in these figures in successive different positions during the course of a working cycle of the boring bit,

FIGURE 4 shows a longitudinal section through a practical embodiment of a latching head,

FIGURE 5 is a secondary view in section along the line V-V of FIGURE 4,

FIGURES 6 and 7 represent a partial longitudinal section of the latching head of FIGURE 4 in different stages of its operation,

FIGURE 8 shows a partial longitudinal section of a first modification of the embodiment of the latching head,

FIGURE 9 shows a partial longitudinal section of a second embodiment of a latching head,

FIGURES 10 to 14 represent schematically in longitudinal section different stages in the operation of a boring apparatus having two concentric boring bits in accordance with the invention,

FIGURE 15 is a longitudinal sectional View showing to a larger scale the two latching heads of the two boring bits of the apparatus shown in FIGURES 10 and 14.

FIGURE 16 represents schematically a longitudinal section through a boring apparatus according to the invention in which the latching head of the boring bit is raised under the action of a decrease in pressure created within the hollow shaft,

FIGURE 17 is a partial view of the upper portion of a detail showing in longitudinal cross section a particular type of piston which can be utilised in the apparatus of FIGURE 16,

FIGURE 18 shows schematically a longitudinally section of a modification of the embodiment of the apparatus of FIGURE 16, in which the raising of the boring bit is effected by a high pressure within the hollow shafts,

FIGURES 19 to 22 represent a longitudinal section through different stages of operation of a boring apparatus having a bucket or grab boring bit in accordance with the invention, and

FIG. 23 is a partial view showing a detail of the latching head of FIGS. 19 to 22.

Reference will firstly be made to FIGURES 1, 2 and 3 of the accompanying drawings.

The apparatus shown in these figures, which is intended to bore a hole 1 in ground 2, comprises a set of hollow shafts 3 at the interior of which may circulate in one direction or the other, a flushing liquid schematically shown by the arrows 4.

In a general manner, the devices utilized for controlling the circulation of this flushing liquid may be of any known type not forming part of the invention and these are therefore not described in detail. A boring bit 5, also of any known and convenient type, is mounted to slide along the lower part of the hollow shafts 3. A latching head, schematically shown at 6, is reciprocated within the hole 1 under the control of driving members which are not shown in these figures and of which in the examples which are to follow several practical embodiments will be given. Finally, there is shown an outer tube 8 which is adapted in certain ground to maintain provisionally the walls of the hole during boring and which may also moreover have an additional function which will be pointed out below.

The apparatus whose principles of construction have been set out above operates in the following manner during the course of a cycle of operation of the boring bit,

During the course of its ascending travel, the latching head 6 raises with it the boring bit 5 as is shown in FIG- URE 1.

At the end of its ascending travel, the latching head 6 has a movement relative to a member forming an abutment, for example the tube 8, and this member controls the freeing of the boring bit 5 from the latching head 6. The boring bit 5 thus falls by itself either in free fall or under pressure, as is shown in FIGURE 2, and thus impacts the bottom of the bore hole, as is shown in FIG- URE 3.

The latching head 6 then carries out a descending travel by itself (FIGURE 3).

Finally, at the end of this descending travel, the latching head 6 (position shown in interrupted lines in FIG- URE 3) again latches on to the boring bit 5 and a new cycle of operation may commence.

Reference will now be made to the following figures to point out the details of construction of certain members and to describe the particular embodiments of boring apparatus in accordance with the principles referred to above.

Firstly, there will be described one embodiment of a mechanical latching head which is particularly simple, robust and effective, with reference to FIGURES 4 to 7.

FIGURES 4 and 5 show the position occupied by the different members of the latching head when the latter is latched to and retains the boring bit 5.

The latching head comprises a cylindrical bell 10 the vertical reciprocating movement of which within the bored hole is controlled from the surface. In a first example the bell 10 is directly fixed to the last hollow shaft or tube 3, whereby the set of hollow shafts also is reciprocated, without participating in the movement of the boring bit when the latter impacts the ground, as will be understood by the following.

The bell 10 and the external wall of the tube 3 define an annular space in which are provided recesses 11 by parallel pairs of vertical projections 12 each of which pairs are symmetrically disposed parallel to a vertical radial plane of tube 3 and all of which projections are connected at their bases by a ring 13. Each recess 11 holds a ball 14 which may thus be displaced radially and parallel to the axis of the bell within the limits defined by the recess. The dimension of the balls 14 is such that they cannot leave the recesses 11 whatever be the position that they occupy.

The head is also associated with a cylindrical sliding bolt 15 normally upwardly pressed under the action of a spring 16 interposed at the latching position between a crown 17 forming an integral part of the boring bit 5 and a disc 18 carried at the upper part of the bolt 15.

The latter also carries an external disc 19 whose function will be apparent from that which is to follow.

During fabrication, that portion of the latching assembly which is permanently mounted on bit 5 may be mounted on the bit in any well-known manner. For example, crown 17 may first be welded or bolted onto the outer circumference of bit 5 and spring 16 may then he slid around the upper portion of bit 5 until its lower end rests on crown 17. Bolt 15 could originally be in two parts: an upper

part comprising discs

18 and 19; and a lower part comprising crown abutment disc 18. The lower part can be placed in position around bit 5 prior to the mounting of crown 17 and spring 16. The upper part of bolt 5 can then be slid along the upper portion of bit 5 until encountering spring 16 and then forced downward, compressing spring 16, until contacting the lower bolt portion, which lower portion may be temporarily held in position by any suitable auxiliary means. The two bolt portions may then be permanently welded or bolted together to produce the completed assembly shown in FIG. 4.

The boring bit 5 is terminated at its upper part by a cylindrical latching sleeve 29 which has at its exterior a neck 20a and two conical ramps 26b and 200.

The latching head described above functions in the following manner: in the latching position shown in FIGURES 4 and 5, the balls 14 rest on the ring 13 and are also wedged between the cylindrical upper wall of the bolt 15 and the conical upper ramp 20b of the latching sleeve 20 which is in fact urged downwards under the action of the weight of the boring bit 5. Thus, when the tube 3 and the bell 10 which is integral therewith are raised, the boring bit 5 is also raised.

When the assembly comes to a predetermined height above the bottom of the bore hole, the outer disc 19 fixed to the bolt 15 comes into contact with a fixed abutment, constituted for example by the tube 8 referred to above, as is shown in FIGURE 7. The bolt 15 thus slides towards the bottom (arrow f compressing the spring 16, and the balls 14 are moved outwardly by the conical ramp 20b (arrow f The boring bit 5 is no longer retained and drops by itself in free fall (arrow f Finally, when the assembly formed by the tube 3 and the bell 10 descends again and contacts the boring bit 5 at the end of the descending travel, i.e. at the bottom of the bored hole (arrow f FIGURE 6), the end of the latching sleeve 20 firstly pushes the balls 14 towards the exterior to a position which is shown in dash-dot lines. On continuing the descending movement, the ring 13 pushes the bolt and compresses the spring, thus acting as a damping device or shock absorber and this sliding towards the base of the bolt ensures that the balls 14 drop and lodge between the conical ramp 20c and the inner wall of the bolt 15. After these positions, the members constituting the latching head effect the raising of the boring bit at the same time as the tube 3 is raised, as is shown in FIGURE 4.

There has been shown in FIGURE 8 a partial longitudinal section of a first modification of the embodiment of the latching head of FIGURES 4 to 7 which differs therefrom only in that the cylindrical bolt is located towards the interior of the assembly, around the tube 3, whilst the latching sleeve of the boring bit 85 is located towards the exterior of the assembly. The remainder of the elements shown in FIG. 8 correspond to similar elements of the structure of FIGS. 47 in the following :manner: element 92 is the equivalent of element 12; element 97 is the equivalent of element 17; element 98 is the equivalent of element 18; and element 99 is the .5 equivalent of element 19, but is placed at the bottom of bolt 95 whereas element 19 is at an intermediate point of its bolt 15. Element 39 is positioned so that its outer portion can engage tube 8 when the latching head is raised to a sufiicient height. When this occurs, bolt 95 is depressed, freeing bit 85. All of the remaining elements of FIG. 8 are identical with their correspondingly numbered elements of FIGS. 47. It will be apparent that the operation of this head is the same as that described above.

FIGURE 9 shows yet another modification of the latching head in which the bell 10 of FIGS. 4-8 is replaced by a slightly modified, but substantially equivalent, bell 96. In accordance with this embodiment, the cylindrical bolt 105 is provided with slots 165a normally located at the upper part of the recesses 11, as shown in dotted lines. For this position, balls 14 are held between the neck Zita of the boring bit 5 and the non-slotted wall of the cylindrical bolt 105. The unlatching of the boring bit 5 is effected when a pin 21, which is normally upwardly pressed by a spring 22, comes into contactwith the stop 8. Pin 21 is integral with bolt 165 and is surmounted by an engaging finger 21,, which is rigidly connected thereto and which is the functional equivalent of the disc 19 of FIGS. 4-7. Finger 21,, is positioned so that its portion furthest away from shaft 3 will encounter the lower extremity of tube 8 when the latching head is raised to a sufficient height. Spring 21 is maintained in compression and is held between the lower surface of finger 211 and the upper surface of bell 90. A ring 21 is aligned with a passage in bell 90 and has an opening which is large enough to permit pin 21 to slide longitudinally with respect thereto. Ring 21,, may be rigidly fastened to hell 9%} and serves to guide pin 21. One assembly of

elements

21, 21 and 21;, may be provided for each ball 14 or, since bolt 105 is a unitary annular member, only two or three of these elements need be used which assemblies may be spaced around the circumference of bolt 105. At this moment, the bolt 165 slides downwards and the balls 14 locate in the slots ItlSa releasing the boring bit 5.

There will now be described a boring apparatus comprising two concentric boring bits which allows a hole of large diameter to be bored by successive advancing movements of each boring bit. This apparatus is shown in FIGURES 10 to 14 which show the different successive positions of the members of the apparatus during their operating cycle, and also in FIGURE 15 which shows the latching heads of the two boring bits in greater detail.

In conjunction with this apparatus there may be utilized the flushing process .by circulation of a liquid, known in the drilling art as air lift process; this process consists in injecting air under pressure to the interior of the hollow shafts. The column of liquid contained in the set of shafts is thus emulsified with the air and lightened as a consequence in such a manner that there is established a rising circulation in these shafts which brings about a complete flushing. The air .lif process is fully described in US. War Department Technical Manual TMS- 297 entitled Well Drilling, chap. 10, sec. 3, par. 138, published on November 29, 1943.

The apparatus, as is particularly seen in FIGURE 15, comprises a set of hollow shafts 3, a first latching head 6 cooperating with a first internal boring bit 5,, and a second latching head 6 cooperating with a second external boring bit 5 The two latching

heads

6 and 6 are constructed for example in a manner roughly parallel to that of the latching head shown in FIGURES 4 to 7 and certain specific details and differences will be explained at greater length herebelow.

In FIGURES 10 to 15 those members which correspond roughly to the same members of the preceding figures have been given the same reference numerals but with the indices i or e according as the members cooperate respectively with the interior boring bit 5, or the exterior boring bit 5 So far as the latching head 6, is concerned, it will be convenient merely to note, as will be particularly seen from FIGURE 15, that the bell 10 is fixed to the hollow shaft 3 by means of a fastening collar and a series of radial supports connected between said fastening collar and bell I0 and that the unlatching stop for freeing the boring bit 5 is constituted by a cylindrical sleeve 8 fixed to the inside of the latching head 6 which is mounted to slide along the hollow shaft 3 by means of a guide collar defining an annular space 24 with shaft 3 and by means of a series of radial supports fastened on a frusto-conic closing portion and connected between said guide collar and both hell w and tube 8,.

So far as the latching head 6 is concerned, it will be observed that the unlatching stop for freeing the boring bit 5 is constituted by the disc 19 fixed to the outside of the internal bolt 15 As will be seen from that which is to follow, this disc 19 is used to move lugs 25 passing through apertures in the boring bit 5 and connected at the lower ends of rods 26, whose other ends are attached to the cylindrical bolt 15 of the latching head 6 Reference will now be made to FIGURES 10 to 14 in order to describe the method of operation of the apparatus described above.

The assembly of members of the boring apparatus has been shown at rest in FIGURE 10. The lower hollow shaft 3 is at the bottom of the bored hole. The process of flushing by air lift is put int-o operation in such a manner that the flushing liquid circulates in the direction shown by the arrows; thus the base of the bored hole is swept by the liquid, and the mixture of liquid and detritus is driven up through the interior of the shafts 3 towards the surface of the ground some of the descending liquid will inevitably pass through annular space 24 into the space directly below seating 23. The latching head 6 fixed to the shaft 3 rests on the internal boring bit 5, which is in the latched position. The external boring bit 5 also supports the latching head 6 in the latched position so that it may slide around the shaft 3.

When the shaft 3 is raised as is shown on FIGURE 11, the assembly formed by the shaft 3, the latching head 6, and the internal boring bit 5 rises, the exterior boring bit 5 and its latching head 6 remaining at rest.

When the external unlatching disc 19 for the latching head 6 comes into contact with the stop sleeve 8 the bolt 15, is relatively pushed downwards and the inner boring bit 5, is freed and drops in free fall (FIGURE 12).

If desired, the shaft 3 may be relowered to latch again on to the .internal boring bit 5 and recommence the cycle of operations up to dropping this boring bit. This method of working effects impacting of the base of the bored hole only with the internal boring bit 5 thus to make a preliminary central hole.

In accordance with another method of operation, the hollow shaft 3 is continued to be raised. After a certain travel, the bell 19,- of the internal latching head 6 passes into the tube 8 fixed at the inside of the latching head 6 and into a seating 23 (FIGURE 15) arranged in such a manner that the flushing liquid which is contained therein is driven by the latching head 6, through the annular space 24 between the shaft 3 and the external latching head 6 due to the play present between the members. Thus, the actual contact between the latching

heads

6 and 6 is damped.

The shaft 3 continuing to rise, and the latching head 6 supporting the latching head 6 the assembly formed by the shaft 3, the latching heads 6 and 6 and the external boring bit 5 take up the position shown in FIGURE 13. In this position, the stop 19 previously referred to 0perates on the rods 26 and consequently upon the bolt 15 The fixed external boring bit 5 then drops in free fall (FIGURE 14).

At this moment, the hollow shaft 3 may be lowered but without going to the bottom of the bored hole in such a manner as only to relatch the external boring bit 5 and 7 thus to bring about an annular churning of the bottom of the hole.

On the other hand, by lowering the hollow shaft to the bottom, the internal boring bit is also relatched.

It will be understood that there is a great reliability in the use of the boring apparatus shown in FIGURES 10 to 15, and that the choice of the best method of operation depends essentially on the nature of the ground to be bored.

It is observed that, whatever method of operation be effected, continuous evacuation of the detritus is effected and that the set of hollow shafts are not subjected to the shocks on the boring bits, the latter dropping by themselves in free fall.

In the preceding examples, the means utilized for bringing about vertical reciprocating movement of the latching heads are constituted by the set of hollow shafts 3 themselves which are given the appropriate movement.

There will now be described other embodiments of the boring apparatus according to the invention in which the set of hollow shafts remain at rest, separate means being provided for reciprocating the latching heads along the hollow shafts.

These means may consist of an assembly formed by a cylindrical chamber, a piston and a valve and adapted to bring about the displacement of the bell of a single latching head formed in the same manner as those used in the apparatus shown in the preceding figures.

FIGURE 16 shows schematically a longitudinal section through such an apparatus in which the lifting of the boring bit is effected by a lowering of the pressure in the interior of the hollow shafts.

The apparatus comprises a cylinder 27 fixed to the lower end of the set of hollow shafts 3 and extending downwards to a fairly great depth towards the bottom in the form of a skirt.

A shutter valve is located at the interior of the cylinder 27 and comprises a seating 28 fixed by struts or braces 29 to the upper end of the cylinder 27, and a conical valve 30 which is made as heavy as is found desirable.

The seating 28 of the valve constitutes the upper end of a hollow interior shaft 3 about which may slide a piston 31 in a fluid tight manner between the shaft 3 and the cylinder 27.

The piston 31 is provided, for example as shown in FIGURE 17, with fittings 32 made of a special rubber having a constitution similar to that utilized in mud pumps for rotary boring machines. The fittings 32 are assembled together in pairs by riveted pins 32 and the pairs of fittings 32 are interspaced by distance pieces 33 adapted to give to the piston 31 a length suflicient that it may be adequately guided in the cylinder 27. The assembly formed by fittings 32 and the pieces 33 is assembled by proper means such as longitudinal rods 31 A bell 101 of a latching head 6 substantially with that shown in FIGS. 4-7 above, with the exception that bell 101 has a central circular opening which permits it to slide freely along shaft 3 is fixed to the base of the piston 31 by securing the lower ends of rods 31 to hell 161. Head 6 has a bolt 126 identical with bolt of FIG. 15.

Moreover, the crown of the piston 31 comes into contact at the end of the ascending travel with stops 34 which are fixed to the valve 30 so as to raise it.

The lower end 53 of tube 3, has a serrated edge which permits it to penetrate into the soil of the bottom of the hole.

The operation of the apparatus described above is as follows:

Assuming that the boring bit 5 is at rest at the bottom of the bored hole which itself is assumed to be filled up to the surface with a flushing liquid, the tube 3 is just above the bottom of the bored hole but suspended in tension from the surface. The piston 31 may be in any position. The valve is closed and rests on the seating 28 shutting off the tube 3 Due to its weight, the piston 31 tends to descend.

A light pressurizing of the interior of the hollow shafts 3 applied from the surface is transmitted to the piston 31 which descends and causes the bell 10 to cover the latching sleeve 20' of the boring bit 5. Latching sleeve 20 is identical with sleeve 20 of FIG. 4, with the exception that sleeve 20 has at least two openings in the lower portion of its wall for the passage of the lower extremities of rods 36. The latching between the bell 10 attached to the piston and the boring bit is thus accomplished.

The set of shafts 3 is then subjected to a rapid lowering of pressure from the surface by means of the flushing process known as air lift.

The interior of the cylinder 27 is subjected to a lowerering of pressure and the piston 31 is pushed by the corresponding under-pressurizing exerted by the column of liquid filling up the bored hole, and rises taking with it the boring bit 5. The force exerted by the decrease in pressure thus created may attain several dozen meters of water according to the depth of the bored hole and the height of the column of tubes by reason of the rapid emptying of the set of hollow shafts 3 towards the exterior by the air lift. The extent of this reduction in pressure is limited in dependence upon the weight of the valve 30 and the diameter of its seating.

At the end of its travel, the boring bit 5 reaches a boss 35 provided on the tube 3, and during its passage latches on to the rod 36 which, in its turn, applies pressure to the bolt 126 and therefore the boring bit 5 drops in free fall, freeing the piston 31 which continues to rise and then meets the steps 34 which raise the valve 30 due to the pressure which continues to push the piston 31 upward and to the high force acquired thereby.

The opening of the valve 30 allows the detritus accumulated at the bottom of the bored hole to be driven up by the flow of liquid circulating in the direction of the arrows.

It will be apparent that as soon as the boring bit 5 drops in free fall, the piston 31 may be allowed to redescend immediately by pushing it by means of a slight pressure if necessary and to relatch the boring hit again to raise it up and thus effect several successive drops of the boring bit without any intermediate removal of the detritus. The method of operation chosen will depend upon the nature of the ground and the penetration obtained by the cycle of operations.

Reference will now be made to FIGURE 18 which schematically shows a longitudinal section through apparatus which, in principle, is similar to that shown in FIGURE 16, but in which the raising of the boring bit is effected by means of an excess pressure exerted at the interior of the hollow shaft.

In this apparatus, there is provided a cylinder 37 mounted to slide around the lower end of the set of hollow shafts 3 by means of seal members 38. Cylinder 37 is closed at the top and fastened to seal members 38 by means of bolts 31 for example. The cylinder 37 is moreover guided around the seating 39 of a ball valve 46 by another seal member 41, the

seal members

38 and 41 being identical in structural to the piston 31 of FIG. 17, but with the bottom of member 38 being rigidly connected to the upper annular end of cylinder 37 and the bottom of member 41 being rigidly connected to the upper rim of seating 39, both connections being made, for example, by means of suitable bolts 31 in a manner identical with that discussed in connection with piston 31 of FIG. 16, so that seal 38 may slide with respect to shaft 3 and seal 41 may slide with respect to cylinder 37.

The cylinder 37 is fixed, by means of a support 42, to the bell 101, of a latching head 6' for bit 5, bell 101 and head 6 being identical with the similarly numbered elements of FIG. 16. Associated with head 6' and bit is a bolt 126 carrying a rod 36, both of which latter elements are also identical with their corresponding similarly numbered elements of FIG. 16.

It remains to note, so far as the boring apparatus of FIGURES 16 to 18 is concerned, that the cylinders 27 (FIGURE 16) and 37 (FIGURE 18) are extended downwards by a skirt which forms a complementary guide for the boring bit in its ascent or fall. These skirts, on the interior of which the head of the boring bit rests after its fall, allow an easy relatching of the latter after its fall due to the guiding means which they constitute.

Moreover, the variation of the weight suspended from the set of shafts at the moment of lifting of the boring bit and at the moment of its fall is shown, on the one hand, by a variable traction exerted on the suspension system for the boring apparatus and, on the other hand, by a pressure which is exerted on the lower end of the inner shaft 3 These effects may be utilized, on one hand, for controlling certain movements from the surface for varying the weight and to obtain a partial automatic operation of the latter and, on the other hand, to cause the end of the tube 3 to penetrate into the soil by a slight rotation of the set of hollow shafts effected from the surface at the moment when the boring bit is in its ascending travel.

To this end, by a convenient control of the operating pressures, the boring bit may be maintained in an intermediate suspended position and practically without movement.

As a last example, there will now be described, with reference to FIGURES 19 to 22, the application of the invention to a boring apparatus provided with a boring bit having at its base two or more digging shovels or scoops articulated to the boring bit and capable of being reclosed by means of a central control operated from the surface. A closure of the digging shovels towards the axis of the boring bit is particularly efficacious in the boring of alluvial soils such as sands, marls, fine gravels, etc., because it increases the speed of advancement of boring and, moreover, it conducts the detritus'being extracted towards the center of the bored hole in proximity to the flushing tube.

A reference to FIGURES 19 to 23 will show that the upper part of the boring bit 115 is integral with a latching sleeve 100' cooperating with a latching head 116. Latching head 116 and the latching mechanism cooperating therewith are shown in detail in the partial view of FIG. 23. As is there shown, the head 116 comprises a bell 110 having a vertically oriented cylindrical skirt defining its outer periphery and a circular, horizontal closing portion defining its top. This latter portion of bell 110 is rigidly fastened to the upper end of cylinder 137 by means of, for example, a series of spaced bolts 140. A joint 37, which is identical in structure to the piston 31 of FIG. 17, is interposed between cylinder 137 and bell 110 and is rigidly connected thereto by means, for example, of a series of bolts 31 having suitable nuts screwed onto their lower ends. The upper end of sleeve 110' extends upwardly between the side walls of bell 110 and cylinder 137 and is held, when the drill bit is latched, by balls 14 (one of which is here shown) pressed by the lower end of a bolt 136, into a notch in the sleeve. Bolt 136 is slidably mounted in a suitable opening in hell 110 and is normally urged upward, into the position shown in FIG. 23, by means of a compressed spring 22 disposed around the bolt and held between the upper surface of bell 110 and an abutment member 136,, integrally attached to the upper end of bolt 136. The upward movement of bolt 136 is limited by a stop disc 136 rigidly connected thereto. The release of sleeve 100 is effected merely by depressing bolt 136 sufiiciently to permit ball 14 to be displaced into slot 136, and to thus release sleeve 100'. This depression of bolt 136 is eifectuated by the movement of member 136 against stop 118 when head 116 fluid under pressure which is injected thereinto.

is moved upward along shaft 3 to a suflicient height. The boring bit 115 is provided at its base with digging shovels or scoops 43, the closure of which is effected by means of arms 44 attached to a member 45, the vertical movement of which is guided by sliding in a cylindrical central orifice in the base of the boring bit 115. The movement of the member 45 is limited by the attachment piece 46 and the arms 44 which abut against the base 47 of the boring bit 115 in the raising movement, and in the descending movement by a flange 48 which also rests on a shoulder 49 at the base of the boring bit. A spring 50 presses against this flange 48.

The shaft 73, has at its base vent holes or orifices 51 for the detritus.

The end of the shaft 73 is obturated by a large conical member 52 the projection base of which may serve as a support for the sliding member 45 when scoops 43 have penetrated a sufficient distance into the material constituting the bottom of the hole, as is shown in FIG. 22.

The obturation of the vents 51 and consequently of the shaft 73 is effected by raising the shaft in which case contact is effected between the conical member 52 and the base of the member 45. This obturation is completed by means of a joint 53 located on the upper part of the member 45 and creating a seal between member 45 and shaft 73 The joint 53 may be any known type of sealing means and may, in particular, be similar to the piston 31 shown in FIG. 17. Thus, when vents 51 are located within member 45, they are isolated from the outside by seal 53 at the top of member 45 and by member 52 at the bottom thereof.

Within bit 115 is disposed a cylinder 137 terminated at its upper end by an inwardly directed flange which is rigidly connected to the bell 110 of latching member 116. The cylinder is slidably mounted on pipe 3 by means of a joint 38 which is clamped between the upper cylinder flange and bell 111), so that a fluid-tight joint exists between the cylinder and pipe 3. Joint 33 is slidable with respect to pipe 3 and is identical in structure to the similarly numbered joint of FIG. 18. The lower end of pipe 3 terminates, within cylinder 137, in outwardly-extending struts 54 to which are rigidly connected the top of seating 39 and a piston 41 structurally identical with the similarly numbered joint of FIG. 18. Piston 41 is slidable with respect to cylinder 137 and serves to create a fluid-tight region between the upper flange of cylinder 137 and the piston 41. A series of openings between struts 54 permit this fluid-tight region to communicate with the interior of pipe 3. An abutment member 118 is rigidly attached to pipe 3 in a position where it can depress the bole to release bit 115. Bolt 105' is identical in structure with the bolt 105 of FIG. 9 with the exception that the lower horizontal engaging finger of the latter has been moved upward (not shown) to a point above slot 105,,, where it will engage the top of hell 110. The operation of the apparatus is as follows:

The members have been shown in a position of rest in FIGURE 19. The flushing may thus be effected by the process known as air lift and the flushing liquid thus circulates in the direction of the arrows ensuring the raising to the surface of the detritus through the interior of the set of hollow shafts.

The

shafts

3 and 73, (the shaft 73 being connected to the base of the last shaft 3 by means of struts 54), a fluid tight joint 41 and a seating 39 (of a ball valve 49), rest on the bottom of the bored hole and the bell and its associated means rest, in the latching position, on the sleeve 100' fixed to the boring bit 115.

As is shown in FIGURE 20, the boring bit is raised by placing the interior of the set of hollow shafts 3 under an excess pressure. The ball 40 is applied on its seating 39 and the cylinder 137 rises again under the action of the The latched boring bit is also raised. The spring 50 is compressed, presses against the flange 48 of the member 45, and thus tends to maintain the shovels or scoops 43 open.

At the end of the ascending travel, the bolt 105 of the latching head 116 with the exception noted above, comes into contact with the stop 118 fixed, in this embodiment on the last hollow shaft 3. The boring bit is thus freed and the boring bit drops as is shown in FIGURE 21, not only under its own weight, but also due to the pressure exerted by the spring 50 which is thus slackened.

The use of the spring 50 allows the available operating pressure in the equipment at the surface to be employed entirely.

Balls 14 are held in member 116 because these balls have a diameter which is greater than the clearance between the vertical rim of bell 110 and the cylindrical wall of cylinder 137. The size of this clearance has been exaggerated in FIGS. 1922, for purposes of illustration. In a like manner, the distance between balls 14 and bolts 105' has been exaggerated for the same purpose.

In one practical embodiment of the above-described structure, the horizontal, annular cross-sectional area between cylinder 137 and pipe 3 may be made equal to 1000 cm. and the fluid in the region defined by these two members may be subjected to a pressure of 6 kg./crn. so that, the force available for movement of the boring bit will be 6000 kg. Due to the spring, it becomes possible to use a lighter boring bit, having a weight of 2.5 tons for example, which will be more manageable and less cumbersome in transport. It would employ less metal and would be less costly. It may be made with a shape having better hydrodynamic properties so that it may penetrate better into the flushing liquid which it displaces at the bottom of the hole.

This light spring does not take up a large space and may be made in such a manner that it may have for example, in the compressed position, a force equal to the weight of the boring bit, viz. 2.5 tons.

It will thus store, at the moment the boring bit is raised, an energy which it will restore on unlatching Which coincides with the dropping of the boring bit.

This fall is thus not a free fall but is accelerated and the actual force at the point of impact with the bottom of the hole will be increased, especially having regard to the supplementary friction in the fluid due to the increase of speed during the fall, but which are in particular compensated by the improvement of the profile of the boring bit which is obtained as a result of its lightening.

By placing the shafts 3 under a slight depressuring, it is possible to cause cylinder 137 to be drawn downward, carrying latching head down with it until the latter descends onto the upper end of bit 115. It is thereby possible to cause the latching head to once again grip bit 115, whereupon the pressure within cylinder 137 may once again be raised, causing the cylinder to ascend so as to renew a cycle of operation of the boring bit with its shovels or scoops opened.

On the other hand, from the position shown in FIG- URE 21, the shovels or scoops 43 may be closed.

To this end, the set of shafts 3 may be subjected to a rapid depressuring by the process known as air lift, which causes the cylinder to rest on the boring bit 115 by exerting on the latter an increase in pressure tending to cause it to penetrate into the ground.

There follows a relative movement between the

members

45 and 52 tending to apply them one against the other, obturating the lower vents 51 of the shaft 73 The decrease in pressure exerts at this moment its maximum effect (FIGURE 22). The piston 41 then continues to rise in the bored hole and takes along the member 52 which pushes the member 45 in such a manner that the latter has no action on the spring 50.

The slide member 45, which is attached to the arms 44 of the shovels or scoops 43, takes along the arms 44 and the shovels or scoops 43 close.

The detritus removed by the shovels or scoops is in the course of this movement completely broken up and shaked.

Then, either by slackening of the suspension of the set of shafts 3 or, if desired, subjecting them to a slight decrease in pressure, the shafts may be lowered to a position of rest of the base 52 on the closed shovels or scoops 43.

The vent holes 51 are therefore uncovered.

The putting of the air lift into operation causes the valve 40 to be raised and causes the suction of the detritus contained in the shovels or scoops 43, the inclination of the latter assisting in conducting the detritus towards the vent holes.

As soon as it is seen at the surface that the circulation of the flushing liquid is proceeding without carrying in more detritus with it, it will be convenient to reassume the cycle of operations.

Although in the foregoing there have been described certain specific examples of carrying the invention into effect, it will be apparent that it is possible to vary these constructions without in any way modifying the functional organization of the apparatus and also without departing from the scope of the invention.

I claim:

1. Impact drilling apparatus for boring a hole, comprising at least two shafts each having a hollow interior for the circulation therethrough of a flushing liquid, struts connecting said shafts together in tandem, said shafts being axially aligned with the hole, a stop device fixed to the upper end of one of said shafts, a latching head slidably coupled to said one shaft for sliding movement axially therealong, boring bit means slidably coupled to said other shaft for movement axially of both said shafts, a compression spring on the other of said shafts, one end of said compression spring being in engagement with said boring bit means, the other end of said spring being in engagement with said strut, a latching sleeve on said boring bit means, means on said latching head latchably engaging said latching sleeve at the end of the descending travel of said latching head when said boring bit means is located on the bottom of the bored hole, driving means operatively connected with said latching head to raise said boring bit means and said latching head to compress said spring, and stop means on said latching head en- 'gageable with said stop device disengaging said boring bit means from said latching head at the end of the upward travel thereof to relax said compression spring for exerting a pushing force on said boring bit means forcing the descent thereof.

2. Apparatus as claimed in claim 1, including a cylinder movably coupled to the lower of said two shafts and surrounding said lower shaft to form a chamber therebetween, said lower shaft having its upper open end in communication with said chamber, said upper shaft having a lower open end in communication with said upper open end, a ball valve seated on said upper open end, and means to apply pressure through the interior of said upper shaft to maintain said ball seated and pressurize said chamber whereby to overcome the force of said compression spring and raise said latching head.

3. Apparatus as claimed in claim 1, including scoop means articulated to said boring bit means for movement between an open and a closed position, a sleeve slidably coupled to the lower of said two shafts and movable longitudinally therealong, said sleeve having a flange portion engageable with said one end of said compression spring, arm means coupled between said sleeve and said scoop means for opening said scoop means upon compression of said spring and closing said scoop means upon release of said spring.

4. Apparatus as claimed in claim 1, wherein said latching head includes a bell-shaped member, a plurality of ball retaining members peripherally spaced and coupled to said bell-shaped member, a ball in eachsaid, retaining;

members, and retained thereby, a radial ball passageway and a longitudinal ball passageway in each said retaining members permitting radial and longitudinal displacement of said ball, respectively, in said retaining member, and a bolt comprising a sleeve slidably coupled on said one shaft, a spring device connected between said sleeve and said boring bit means normally urging said sleeve into said ball retaining members, said latching sleeve extending into said ball retaining members and spaced from said bolt sleeve for wedging said balls therebetween to retain said boring bit means in engagement with said latching head, means connecting said bolt sleeve with said stopping means to move said bolt sleeve out of said retaining members thereby permitting said balls to move radially and longitudinally out of engagement with said latching sleeve for release thereof.

5. Impact drilling apparatus for boring a hole, comprising:

(a) a set of longitudinally aligned, coupled shafts aligned with the hole being bored and having a hollow longitudinal passage extending completely therethrough for the circulation of a flushing fluid;

(b) boring bit means having a hollow longitudinal passage aligned with the hollow passage of said shafts and positioned around said shafts to move vertically with respect thereto, said bit means having a cylindrical latching sleeve at its upper extremity;

(c) a latching head positioned above said bit and means, said latching head having a central opening through which said set of shafts passes, and latch means mounted on said head for gripping said sleeve when said head descends to a level at which the upper extremity of said bit means is caused to engage said latch means;

(d) a mechanically actuated release mechanism associated with said latch means to cause the latter to release said latching sleeve when said release mechanism is urged into a latch-release position, said mechanism having an abutment surface the downward movement of which causes the said mechanism to move into said latch-release position;

(a) coupling means rigidly connected to said set of shafts and operatively coupled to said latching head to cause the latter to move vertically in the hole being bored; and

(f) triggering means placed above, and in the path of travel of said abutment surface and movable with respect to said latch means, whereby the downward movement of said triggering means depresses said abutment surfaces and causes said latch means to release said sleeve.

6. Apparatus as claimed in claim 5, wherein said latch means includes a bell-shaped member fixed on the lowest of said shafts, a ball-retaining member peripherally disposed in said bell-shaped member having a plurality of recesses each forming a ball passageway radially and longitudinally of said bell-shaped member, a ball retained in each of said recesses for movement radially and longitudinally of said bell-shaped member, said release mechanism including a cylindrical bolt slidable axially on said shafts and including a sleeve portion slidable longitudinally into said recesses, a spring having one end in operative engagement with said bolt, and an external disc connected with said sleeve portion and being provided with said abutment surface, and said boring bit means including a crown, said latching sleeve extending into said recesses and spaced from said sleeve portion for wedging said balls therebetween to retain said boring bit means in engagement with said latching head, the other end of said spring engaging said crown for normally urging said sleeve portion into said recesses, said abutment surface of said external disc engaging said triggering means to compress said spring to move said bolt sleeve out of said recesses thereby permitting said balls to move radially and longi- 14 tudinally out of engagement with said latching sleeve for release thereof.

7. Apparatus as claimed in claim 5, wherein said set of shafts includes at least two shafts having a hollow interior, a cylinder coupled to the one of said shafts and having a skirt portion overlying the other of said shafts, a valve coupled with said one shaft and seated at the top of said other shaft in the hollow interior thereof opening into said cylinder, a piston coupled with said latching means slidably coupled between said other shaft and said skirt portion in fluid tight relationship therewith, and a stop connected with said valve for opening thereof to place said shafts into fluid communication with each other, said piston being engageable with said stop to open said valve at the end of ascending travel of said latching means and means to inject air under pressure into the interior of said shafts whereby to cause said piston to ascend and open said valve.

8. Apparatus incorporating continuous flushing as claimed in claim 5, including hollow tube means encircling at least one of said shafts and spaced therefrom forming a fluid passageway therebetween for the circulation of the flushing fluid in said fluid passageway.

9. Apparatus as claimed in claim 8, including a stop device on said hollow tube means, said stop means engaging said trigger device at the end of the upward travel of said latching means.

19. Apparatus incorporating continuous flushing as claimed in claim 5, wherein said shafts includes a pair of shafts arranged in tandem and means coupling said shafts together.

11. Apparatus as claimed in claim 10, including a cylinder movably coupled to the lower of said two shafts, said cylinder surrounding said lower shaft to form a chamber therebetween, the upper open end of said lower shaft being in communication with said chamber and with the lower open end of the upper of said two shafts, a ball seated on said upper open end, and pressure means acting through the interior of said upper shaft to seat said ball and pressurize said chamber, thereby raising said latching means.

12. Apparatus as claimed in claim 11, wherein said boring bit means includes a boring bit, a shovel rotatably coupled to said boring bit, a sleeve slidably connected with said lower shaft, an arm having one end pivotally coupled with said sleeve and the other end connected with said shovel, and means to move said sleeve to pivot said arm, thereby to rotate said shovel.

13. Impact drilling apparatus for boring a hole, comprising:

(a) A set of vertically oriented, longitudinally aligned, coupled shafts inserted in the hole being bored and having a hollow longitudinal passage extending completely therethrough for the circulation of a flushing fluid between the upper end of said shafts and the bottom of said hole;

(b) An inner boring bit having a hollow longitudinal passage aligned with the hollow passage of said shafts and having a cylindrical latching sleeve at its upper extremity, said bit being mounted to move vertically with respect to, and around, said shafts;

(c) An outer boring bit having a hollow longitudinal passage aligned with the hollow passage of said inner boring bit and having a cylindrical latching sleeve at its upper extremity, said outer bit being mounted to move vertically with respect to, and around, both said shafts and said inner boring bit;

(d) A first annular latching head rigidly connected to the outer surface of said shafts and disposed wholly within the cylindrical region defining the longitudinal passage through said outer boring bit;

(e) Inner latch means mounted on said first latching head and disposed in the path of travel of said inner bit, said inner latch means having a gripping position in which it grips said sleeve of said inner bit when 15 the latter engages said inner latch means, being movable into a releasing position in which it ceases to grip said inner bit;

(f) An inner release mechanism operatively associated with said inner latch means and movable into an active position in which it urges said inner latch means into its said releasing position to permit the release of said inner bit;

(g) A second annular latching head slidably mounted around said shafts and above said first latching head, and partially disposed in the path of travel of said first latching head;

(h) Outer latch means mounted on said first latching head and disposed in the path of travel of the sleeve of said outer bit, said outer latch means being normally urged into a gripping position in which it grips said sleeve of said outer bit when the latter engages said outer latch means, said outer latch means being movable into a releasing position in which it ceases to grip said outer bit;

(D An outer release mechanism operatively associated with said outer latch means and movable into an active position in which it urges said outer latch means into its said releasing position to permit the release of said outer bit;

(j) First triggering means mounted on said inner release mechanism and placed above, and in the path of travel of, said outer release mechanism for contacting said outer release mechanism and urging it into its said active position; and

1.6 (k) Second triggering means mounted on said second latching head and placed above, and in the path of travel of, said inner release mechanism for contacting said inner release mechanism and urging it into its said active position.

14. .Apparatus as recited in claim 13, wherein said first latching head has an upper bearing surface which acts to support said second latching head when said first head is raised to a predetermined height above the bottom of the hole being bored.

15. Apparatus as recited in claim 13, wherein an annular passage exists between said second latching head and the shafts around which it is mounted for permitting a flow of fluid from the region below said second head to the region thereabove, which regions are external of said shafts.

References Cited by the Examiner UNITED STATES PATENTS 1,730,704 10/1929 Wild 285 X 1,787,001 12/1930 Hunt et a1. 175285 X 2,223,645 12/1940 Solomon 17S267 X 2,829,716 4/1958 Stewart 16698 CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN BENDETT, Examiner.

C. O. THOMAS, W. J. MALONEY, J. A. LEPPINK, A ssz'stant Examiners.

Claims

1. IMPACT DRILLING APPARATUS FOR BORING A HOLE, COMPRISING AT LEAST TWO SHAFTS EACH HAVING A HOLLOW INTERIOR FOR THE CIRCULATION THERETHROUGH OF A FLUSHING LIQUID, STRUTS CONNECTING SAID SHAFTS TOGETHER IN TANDEM, SAID SHAFTS BEING AXIALLY ALIGNED WITH THE HOLE, A STOP DEVICE FIXED TO THE UPPER END OF ONE OF SAID SHAFTS, A LATCHING HEAD SLIDABLY COUPLED TO SAID ONE SHAFT FOR SLIDING MOVEMENT AXIALLY THEREALONG, BORING BIT MEANS SLIDABLY COUPLED TO SAID OTHER SHAFT FOR MOVEMENT AXIALLY OF BOTH SAID SHAFTS, A COMPRESSION SPRING ON THE OTHER OF SAID SHAFTS, ONE END OF SAID COMPRESSION SPRING BEING IN ENGAGEMENT WITH SAID BORING BIT MEANS, THE OTHER END OF SAID SPRING BEING IN ENGAGEMENT WITH SAID STRUT, A LATCHING SLEEVE ON SAID BORING BIT MEANS, MEANS ON SAID LATCHING HEAD LATCHABLY