EP0624204B1 - Machine for forming the taphole of a tank furnace - Google Patents

Abstract

A machine for forming the taphole of a tank furnace in order to apply the lost rod method. The machine includes a housing (20), a drive (42, 44), and a clamp (34) for coupling the drive to the rod (26) while it is being withdrawn. A pusher (34) imparts a pushing force to the rear end of the rod (26) while it is being inserted into the taphole clay. Meanwhile, intermediate guides (55i) surround the rod (26) at several points and are successively placed in a position in which they do not hinder the advance of said pusher (34, 78) on the housing (20).

Description

The present invention relates to a machine for drilling a tap hole of a shaft furnace, designed for implementing the method called "lost rod method" in which, after having closed the tap hole with a mass plugging, a metal rod is inserted into the latter, before its complete hardening, and the latter is extracted at the desired time for the opening of the tap hole. Said machine comprises a mount for supporting the rod during said process, a drive means mounted on the mount so as to develop a traction force, respectively of thrust parallel to the mount, a coupling member for coupling said means drive the rod so as to transmit said tensile force to it during its extraction.

The machines used until now for the implementation of this method of the lost rod are in principle conventional drills, that is to say designed to work with a drill, which however have undergone suitable adaptations and modifications for the implementation of the process.

The working part of these machines, which normally serves to drive a sharp drill in rotation, must include a coupling clamp for the rod and, above all, a powerful bi-directional pneumatic striker to deploy the energy necessary for the introduction and extraction of the piercing rod according to said "lost rod method".

Document FR-A-2520857 discloses a clamp designed to be mounted on the bi-directional striker drill of a conventional taphole drilling machine. For the extraction operation of a drilling rod embedded in the plugging mass, the normal coupling of the drill, used to communicate a rotational movement to a drill, is exchanged against this clamp. The latter then makes it possible to couple the drill to the rear end drill rod and remove it by operating a powerful striker secured to the drill.

Most often one preserves on these drilling machines also the possibility of being able to be able to use the drill with a traditional drill, either to reform or move the taphole, or to drill the hole in a traditional way when the process of the lost rod does can be used for one reason or another. However, to drill the tap hole with a conventional drill, it is necessarily required to exchange the pliers against the normal coupling of the drill, because the jaws of the pliers are not adapted to transmit a rotational movement to a drill.

It will be noted that a powerful striker, as used on these machines, is not without drawbacks. First, it imposes significant stresses and vibrations on the material, in particular on the clamp for coupling with the rod, which is therefore subject to rapid wear. It is also extremely noisy, and often does not meet the increasingly stringent standards aimed at reducing the noise level in an industrial environment.

The drawbacks of the striker could therefore encourage the removal of percussion during the introduction and extraction of the rod.

Document EP-A-0379018 discloses a drilling machine for implementing the "lost rod process" which does not use a striker for the extraction of the drilling rod from the hardened plugging mass. To this end, the proposed machine uses a clamp movable at the front of the carriage by a powerful hydraulic cylinder whose stroke is, for reasons of space, significantly smaller than the length of the drilling rod to be extracted. This cylinder has the pliers make several strokes near the front end of the mount to extract the rod from its total length from the hole of casting. It follows that the extracted drilling rod - which is hot, deformed and dirty - must completely pass through this extraction clamp. In addition, the extraction clamp is exposed to the projected splashes from the tap hole when it is opened. Document EP-A-0379018 contains no indication how the piercing rod could be introduced without a striker into the plugging mass previously injected into the tap hole.

Document EP-A-0379018 therefore provides only an imperfect solution for the extraction of the piercing rod without striker and no solution at all for the introduction of the piercing rod without striker into the plugging mass.

The object of the present invention is to provide a machine for drilling a tap hole of a shaft furnace, which is designed for implementing the "lost rod method", and which makes it possible to dispense with '' a powerful bi-directional striker both for extracting the piercing rod from the plugging mass and for its introduction into the plugging mass.

• un affût pour supporter soit une tige de perçage, soit un foret, ledit affût comprenant une extrémité avant qui peut être agencée en face du trou de coulée et une extrémité arrière axialement opposée à l'extrémité avant,
• une foreuse avec un accouplement qui est conçu pour recevoir et entraîner en rotation le foret, ladite foreuse étant montée de façon coulissante sur l'affût,
• un moyen d'entraînement monté sur l'affût de façon à développer un effort de traction, respectivement de poussée parallèlement à l'affût,
• une pince montée sur l'affût entre l'extrémité avant de celui-ci et la foreuse et connectée au moyen d'entraînement, ladite pince comprenant un corps traversé axialement par un canal qui a un diamètre légèrement plus grand que la tige et le foret, des mâchoires déplaçables qui sont agencées autour du canal et qui sont conçues de façon à pouvoir agripper l'extrémité arrière de la tige engagée dans le canal pour lui transmettre un important effort de traction lorsque la pince est déplacée en direction de l'extrémité arrière de l'affût,

   caractérisée

• en ce que la pince est déplaçable par ledit moyen d'entraînement le long de l'affût sur une longueur qui correspond approximativement à la longueur de la tige,
• en ce qu'une clavette est engageable dans un logement du corps de la pince de façon à obturer axialement le canal et à pouvoir transmettre à l'extrémité arrière de la tige engagée dans le canal un effort de poussée axiale lorsque la pince est déplacée en direction de l'extrémité avant de l'affût,
• en ce que ladite clavette libère lorsqu'elle est retirée de son logement le canal de la pince, de façon à pouvoir traverser ce canal avec le foret et accoupler ce dernier à l'accouplement de la foreuse située entre la pince et l'extrémité arrière de l'affût,
• en ce que des guides intermédiaires sont montés sur l'affût entre l'extrémité avant de celui-ci et la pince, lesdits guides ayant sur l'affût des positions opérationnelles, dans lesquelles ils cernent la tige à plusieurs endroits espacés axialement lors de son introduction dans le trou de coulée préalablement obturé avec la masse de bouchage, et des positions de garage dans lesquelles ils ne gênent pas l'avancement de ladite pince vers l'extrémité avant de l'affût, et
• en ce que ces guides intermédiaires sont, au fur et à mesure de l'avancement de la pince en direction de l'extrémité avant de l'affût, déplaçable desdites positions opérationnelles dans lesdites positions de garage.

According to the present invention, this objective is achieved by a machine for drilling a tap hole of a shaft furnace, comprising

• a carriage for supporting either a drilling rod or a drill, said carriage comprising a front end which can be arranged opposite the tap hole and a rear end axially opposite the front end,
• a drill with a coupling which is designed to receive and rotate the drill, said drill being slidably mounted on the carriage,
• a drive means mounted on the carriage so as to develop a traction force, respectively a thrust force parallel to the carriage,
• a clamp mounted on the carriage between the front end thereof and the drill and connected by means drive, said clamp comprising a body axially traversed by a channel which has a diameter slightly larger than the rod and the drill, movable jaws which are arranged around the channel and which are designed so as to be able to grip the rear end the rod engaged in the channel to transmit a large tensile force to it when the clamp is moved towards the rear end of the mount,

characterized

• in that the clamp is movable by said drive means along the carriage over a length which corresponds approximately to the length of the rod,
• in that a key can be engaged in a housing of the body of the clamp so as to close the channel axially and to be able to transmit to the rear end of the rod engaged in the channel an axial thrust force when the clamp is moved in direction of the front end of the carriage,
• in that said key releases when it is removed from its housing the pliers channel, so that it can cross this channel with the drill and couple the latter to the coupling of the drill located between the pliers and the rear end on the lookout,
• in that intermediate guides are mounted on the carriage between the front end of the latter and the clamp, said guides having on the carriage operational positions, in which they surround the rod in several places axially spaced during its introduction into the taphole previously closed with the plugging mass, and garage positions in which they do not hinder the advancement of said clamp towards the front end of the mount, and
• in that these intermediate guides are, as the clamp advances in the direction of the front end of the mount, displaceable from said operational positions to said garage positions.

According to a main characteristic of the present invention, the metal rod is guided, during the insertion operation, by intermediate guides mounted on the carriage and surrounding the rod in several places. These intermediate supports prevent the rod from starting to flame when one applies, by means of the sliding pliers, provided with its key and driven by a powerful driving means, an appreciable axial thrust at one end of the rod for driving its opposite end into the plugging mass with which the tap hole was previously sealed.

It will be noted that intermediate supports on the lookout of a drilling machine are already known for other reasons.

Document GB-A-2095381 presents a drilling machine provided with an intermediate support between an impact drill and the front support of the drilling machine. The purpose of this intermediate support is to avoid a cantilever support for a drilling rod or a drill bit in the coupling of the impact drill. Such a cantilever support could possibly occur, if the front end of the drill rod or bit was consumed in the tap hole. It will also be noted that the aforementioned document explicitly recommends the introduction of the piercing rod into the obturation mass using a striker secured to the drill.

Document US-A-5,069,430 relates to a machine for drilling a taphole of a shaft furnace which is exclusively equipped for drilling the taphole using a rotary drilling machine driving a cutting head drill. More specifically, it is proposed to work with a drill comprising several segments of rods coupled to one another. To prevent these coupled segments from forming an arrow, when the drill is supported on the carriage of the machine, it is proposed to support the drill, between the front support and the drill by a movable support attached to an endless chain. Too large a deflection of the drill bit supported on the mount would cause the drill bit to deviate from its ideal trajectory.

It is important to note here that drilling the tap hole does not raise the same problems at all as the method of opening the tap hole using a drilling rod embedded in the plugging mass. Indeed, the axial forces that the drill must transmit to the drill are completely negligible compared to the forces to be transmitted to the drilling rod to introduce the latter into the blocking mass, respectively compared to the tensile forces to be transmitted to the rod for extract the latter from the hardened stopper mass. Document US-A-5,069,430 could therefore not provide any contribution to the solution of the problem underlying the present invention.

The main advantage of the present machine is to be able to introduce the rod all at once in the blocking mass without having to use a noisy striker imposing significant vibration stresses on the equipment and on the machine.

Another advantage of the present invention resides in the fact of being able to extract the piercing rod from the plugging mass by coupling the clamp to the rear end of the rod and then withdrawing the clamp towards the rear end of the mount .

An additional advantage of the machine according to the invention is that there is no need to disassemble the pliers, used for the application of said "lost rod process", when one wants to drill the tap hole with the using a conventional drill.

When, during the introduction of the piercing rod into the plugging mass, the clamp advances towards the front of the carriage as the rod sinks into the blocking mass, said circumferential guides must be removed one after the other, as they would hinder the advancement of the clamp on said carriage.

This can for example be done manually by stopping each time the movement of the clamp just before the guide that it risks striking, by dismantling this guide, and by continuing the movement of introduction of the rod to the next guide.

The present invention however also proposes preferential solutions making it possible to put said guides automatically, that is to say without stopping the introduction movement and without intervention of the operator of the machine, in a position which does not interfere with the clamp. as it advances towards the front of the carriage.

In a preferred embodiment, said guides can therefore slide on the carriage. They can then be provided with their own drive system to drive them to a garage position, at the front of the carriage, as and when they risk hampering the progress of the clamp. However, they can also be advantageously driven or pushed, by the clamp drive means or by the clamp itself in a garage position at the front of the carriage as the advancement of the pliers.

It will be appreciated that the present invention also provides preferential solutions for automatically rearranging said sliding guides on the carriage in their initial operating position, that is to say that which corresponds to the start of the rod introduction operation. .

In an alternative embodiment, said guides each consist of two halves surrounding, when assembled, the rod circumferentially over a certain length. When the clamp risks striking such a guide, the two halves are separated laterally by means appropriate, thus freeing the path of the clamp. These guides have the advantage that they do not in principle require a garage position at the front of the carriage.

The drive means selected for the clamp preferably comprises one or more endless chains mounted on the carriage and driven by at least one powerful motor, the direction of rotation of which can be reversed to guarantee both the insertion operation and the rod extraction operation. However, it is also conceivable to make this drive means with hydraulic cylinders or a screw and nut system, or a combination of several of these systems.

• la Figure 1 montre une coupe longitudinale d'un premier mode de réalisation de la machine proposée, au début de l'opération d'introduction d'une tige dans la masse de bouchage;
• la Figure 1a montre une vue en plan de la machine selon la Figure 1;
• la Figure 2 montre une coupe longitudinale de la machine selon la Figure 1, après que l'opération d'introduction de la tige est terminée;
• la Figure 3 montre une élévation d'une variante de la machine proposée, au début de l'opération de l'introduction d'une tige dans la masse de bouchage;
• la Figure 4 montre une exécution préférentielle d'un guide intermédiaire;
• les Figures 5 et 5a montrent des coupes partielles à travers une exécution préférentielle d'une pince lors de l'opération d'introduction de la tige les plans de coupe des 2 Figures étant décalés de 90°;
• les Figures 6 et 6a montrent des coupes identiques aux Figures 5 et 5a, lors d'une opération de forage avec un foret classique.

Other advantages and characteristics will emerge from the detailed description of an advantageous embodiment, presented below, by way of illustration, with reference to the appended drawings in which:

• Figure 1 shows a longitudinal section of a first embodiment of the proposed machine, at the start of the operation of introducing a rod into the blocking mass;
• Figure 1a shows a plan view of the machine according to Figure 1;
• Figure 2 shows a longitudinal section of the machine according to Figure 1, after the rod insertion operation is completed;
• Figure 3 shows an elevation of a variant of the proposed machine, at the start of the operation of introducing a rod into the blocking mass;
• Figure 4 shows a preferred embodiment of an intermediate guide;
• Figures 5 and 5a show partial sections through a preferred execution of pliers during the operation of introducing the rod, the section planes of the 2 Figures being offset by 90 °;
• Figures 6 and 6a show sections identical to Figures 5 and 5a, during a drilling operation with a conventional drill.

All the Figures have the same reference numbers to designate the same parts.

For the description of the construction of the machine, reference is made for example to Figures 1 and 1a. The frame of the drilling machine is constituted by a mount 20. This mount is for example supported in a conventional and known manner at the end of a support arm (not shown). This support arm can pivot around a console to move the drilling machine between a garage position and an operative position and vice versa.

The mount 20 can for example be formed of two parallel beams 20a, 20b joined together. In Figure 1 we only see the beam 20a, the beam 20b having been removed to show more details. The two beams 20a and 20b have, on their inner face, two rails 22 and 24 arranged face to face. Only the rail 22 is shown in Figure 1.

The reference 26 designates a piercing rod, also called a "lost rod", used in said "lost rod method" described in the preamble.

At the front of the machine we see a support 28 which is preferably a screen support of the kind proposed by European patent application EP 0 064 644. This comprises two flaps mounted at the front of the mount 20 , that is to say in front of the tap hole when the machine is in the operative position. These flaps can pivot between an open position facilitating the engagement and gripping of the rod 26 for the extraction thereof and a closed position in which they define a support opening for the rod 26. The two flaps constitute thus a support and at the same time form a splash protection shield coming from the jet leaving the tap hole when the latter opens.

Between the two beams 20a and 20b is mounted, parallel to the rails 22 and 24, at least one endless chain 44. This chain 44 is stretched between a driven toothed wheel 45 mounted at the front of the mount 20 and a toothed wheel driving 46 mounted at the rear of the carriage 20. The driving wheel 46 is driven by at least one motor 42, fixed on the carriage 20.

It is preferably a hydraulic motor whose direction of rotation can be reversed by a suitable control system.

Reference 34 designates a clamp intended for the introduction and extraction of the rod 26. It is preferably the clamp described below. The clamp 34 is supported by a carriage 36 sliding freely along the mount 20, for example using the pads 37 guided in the rails 22 and 24 mounted on the two beams 20a and 20b of the mount 20. The carriage 36 is fixed to the endless chain 44 and can be driven by the latter between a stop 50 mounted at the front of the carriage 20 and a stop 51 mounted at the rear of the carriage 20 and vice versa. The stroke between the two stops 50 and 51 is approximately equal to the length of the rod.

We see in Figure 1 that the carriage 36 can also support a working member 32. This working member which is provided with a coupling 30 for a conventional drill usually comprises a rotary impact drill. Its presence is justified to be able to drill, if necessary, a tap hole with the conventional drill. It should however be emphasized that the working member 32 is not used in the lost rod process and that it could be removed if conventional drilling of the tap hole is never used, or if this drilling can be done in another way. Of course the working member 32 could also have its own carriage and its own drive means.

We will now describe other characteristics of the machine according to the present invention and at the same time study its operation for introducing the rod 26 into the tap hole and for extracting it.

Preferably the rod 26 is loaded into the machine when the latter is in the garage position and when the clamp 34 occupies a position at the rear of the carriage (see Figure 1).

The loading is carried out by threading the rod 26 into the clamp 34 and introducing it into several intermediate guides (55 ₁ , 55 ₂ , 55 ₃ ), which are placed in several places almost equidistant from each other on the carriage 20.

The purpose of these guides (55i) is to prevent buckling of the rod 26 when the clamp 34 applies an axial thrust thereto during the insertion operation.

It should be noted that the number of intermediate guides and their spacings will be determined as a function of the characteristics of the rod (diameter, length, material, etc.) and of the force necessary to introduce the rod 26 into the blocking mass. . This effort is mainly determined by the characteristics of the blocking mass and, inter alia, by its hardening speed.

To be effective, each guide (55i) must surround the rod 26 so as to avoid any lateral escape of the latter when the latter is subjected to an axial thrust at its end opposite the taphole. In addition, the distance between two successive guides must not be too great, otherwise there is a risk of the rod 26 buckling between two guides (55i), which may lead to the limit of complete blockage of the rod between these two guides.

In order to be able to apply the present method during the introduction of a rod, it is forced to successively remove said intermediate guides (55 ₁ , 55 ₂ , 55 ₃ ) from the trajectory of the clamp 34 as it is forward movement of the carriage 20. This is not embarrassing in itself for the success of the present method, because the more the clamp 34 advances, the more the length of the rod decreases and fewer intermediate guides are necessary. However, it would be tedious to stop the advancement of the clamp 34 in front of a guide each time to dismantle the latter manually. The present invention thus presents solutions for automatically removing these intermediate guides when the clamp 34 advances towards the front of the mount 20 to push the guided rod, by an axial thrust on its free end, into the blocking mass.

In a first solution, it is proposed to use guides arranged slidingly on the carriage 20. These guides (55 ₁ , 55 ₂ , 55 ₃ ) will then be pushed by the clamp 34 or the carriage 36 towards the front of the lookout 20 as the introduction of the rod 26 progresses, that is to say that the clamp 34 advances.

That is to say that the carriage 36 first meets the guide 55 ₃ on its path, it rests on it and pushes it in front of you. After a certain distance the guide 55 ₃ is supported on the guide 55 ₂ and the carriage now pushes the two guides 55 ₃ and 55 _{2 in} front of you. Figure 2 shows the end of the insertion operation. The carriage 36 is stopped against the stop 50 and the three intermediate guides 55 ₁ , 55 ₂ , 55 ₃ are located, one against the other, in the garage position in front of the carriage 36.

Figure 3 shows a preferred embodiment of a sliding guide. It has a hook 56 which is for example engaged with grooves in its feet 57 between the lower flanges of the beams 20a and 20b forming the mount. It should be noted that the mounting of the hook must allow it to slide on the carriage 20, while avoiding warping of the hook when it is subjected to offset forces.

In order to be able to accommodate the rod 26 easily in the hook 56, the latter has a defined lateral notch by two horizontal edges which are spaced a distance slightly greater than the diameter of the rod 26. Before starting the operation of introducing the rod 26 into the taphole, this lateral notch is closed using 'A part 58 which is perpendicular to the two horizontal edges, in order to clearly define the rod 26 and to prevent it from escaping laterally from the hook 56. The part 58 can be articulated on the hook 56 and can be advantageously provided with a lever 59 in order to be able to easily close and open said lateral notch manually. It would however also be possible to fully automate this opening and closing of said notch.

In an alternative embodiment of said guides, the latter consist of two symmetrical halves which can be separated laterally from the rod 26 when the clamp 34 is approached. From the operating point of view, this variant is strictly equivalent to the predescribed variant of the sliding guides; it will therefore not be described in detail below.

It will be appreciated that the present invention also provides a preferred embodiment which allows the guides (55i) to be brought back from their garage position to the front of the carriage, which they occupy at the end of the operation for introducing the rod in the closure mass, in their operative position which they must occupy at the start of said introduction operation.

In Figure 1 we see for this end fingers 53 ₁ , 53 ₂ , 53 ₃ equidistant which are integral with the chain 44. These fingers bear on the sliding guides 55 ₁ , 55 ₂ , 55 ₃ when the chain 44 is running rear, that is to say when the carriage 34 is brought back from the front of the carriage to the rear of the carriage. This device therefore allows an automatic rearrangement of the sliding guides 55 ₁ , 55 ₂ , 55 ₃ at the end of the rod insertion operation, by a simple retraction of the carriage 36. A similar effect can moreover, be obtained by connecting the sliding guides 55 ₁ , 55 ₂ , 55 _{3 to} each other and to the carriage 36 by rods 54 ₁ , 54 ₂ , 54 ₃ , guided in eyelets 60, 60 ′ integral with the hooks 56 (cf. Figures 3 and 4). These rods could of course also be replaced by chains or telescopic rods.

The clamp 34 preferably used on a machine according to the present invention is shown in Figures 5, 5a, 6 and 6a.

This clamp 34 comprises a clamp body 75 crossed axially by a bore or channel 74 having a diameter slightly larger than the rod 26. We see that it is a uni-directional clamp designed for the extraction of the rod 26, that is to say that it comprises 2 jaws 70, 72 arranged symmetrically around the axial channel 74 and displaceable obliquely towards the axis of this channel 74 in the direction of the front of the carriage. It follows that under the action of a pull towards the rear of the carriage, allowing the operation and the extraction of the rod, the jaws 70, 72 automatically bite into the end of the rod 26 placed in the channel 74 and thus ensure perfect coupling of the clamp 34 with the rod 26. However, this is not the case during the introduction of the rod.

Thanks to a trick proposed by the present invention, this uni-directional clamp can however also be used with the present machine for the introduction of the rod 26 into the plugging mass. To this end the present invention proposes to arrange in the channel 74, behind the jaws 70, a mechanical stop in order to provide a fulcrum for the rod 26 during said insertion operation.

It is more precisely proposed to carry out this mechanical stop in the channel 74 so that it is easily removable. It is thus possible to cross said clamp 34 with a conventional drill 27, when a drilling with the working member 32 placed at the rear of the clamp 34, as shown in Figures 6 and 6a.

In FIGS. 6 and 6a it can be seen that this removable mechanical stop is achieved by introducing a key 78 into a mortise 76 which crosses the channel 74 perpendicularly. This key 78, which has a height slightly greater than the diameter of the rod 26, is secured in 80 against inadvertent displacement. However, it is also possible to carry out this mechanical stop using a key 78 actuated for example by a pneumatic circuit, which would avoid human intervention on the clamp even to close or open said channel 74.

In Figures 6 and 6a we see that for a drilling operation said key 78 is removed. The drill 27 can thus pass through the clamp 34 to be introduced into the coupling 30 of the working member 32, where it is blocked by an anti-gyratory stop 80.

Returning to said method of the lost rod, and more precisely to the operation of introducing the rod 26 into the semi-hardened plugging mass, it can be seen that when the rod 26 is threaded into the clamp 34 in which the key 78 is in place, and when all the intermediate guides are closed and suitably arranged, the motor 42 can be actuated to advance the clamp 34 and thus push the rod 26 into the blocking mass. Since the rod 26 is surrounded in several places by the guides 55 ₁ , 55 ₂ , 55 ₃ , it is not likely to buckle, although it is subjected to an appreciable axial thrust force. As the carriage 36 advances, the rod 26 sinks into the blocking mass, and the intermediate guides 55i which hinder this advancement are either pushed forward, as described above, or moved laterally.

For the extraction operation of the rod 26, the free end of the latter is threaded into the clamp 34 which is stopped against the stop 50. The clamp 34 is closed by actuating the jaws 70 and 72 which grip said end of the rod. Then the motor 42 is actuated to withdraw the carriage 36 towards the stop 51. There is naturally no need for the intermediate guides 55 ₁ , 55 ₂ , 55 ₃ , because the rod is not subjected to compression but to traction . These guides only serve as intermediate supports for the rod as the latter is removed from the tap hole. It is also important to note that in the last phase of the extraction, the screen support 28 is preferably closed so as to protect the front of the mount against splashing.

The present invention provides a machine which makes it possible to introduce a piercing rod into the plugging mass without striker, by exerting on the end of the latter a simple powerful axial thrust, which has been judged as not possible until now. . In addition, this machine is distinguished by a simple and robust design, and it will be appreciated, among other things, that it provides better environmental protection by an almost silent operation.

Claims (8)

1. Machine for piercing a taphole for a shaft furnace, comprising

   a mounting (20) for supporting either a piercing rod (26) or a drill bit (27), the said mounting (20) comprising a front end which may be arranged facing the taphole and a rear end axially opposite the front end,

   a drilling apparatus (32) with a coupling (30) which is designed to receive and rotationally drive the drill bit (27), the said drilling apparatus (32) being mounted so as to slide on the mounting (20),

   a drive means (42, 44) mounted on the mounting (20) so as to develop a traction force or thrust force respectively, parallel to the mounting (20),

   a clamp (34) mounted on the mounting (20) between the front end of the latter and the drilling apparatus (32) and connected to the drive means (42, 40), the said clamp (34) comprising a body (75) which is traversed axially by a channel (74) which has a diameter slightly greater than the rod (26) and the drill bit (27), and movable jaws (70, 72) which are arranged around the channel (74) as to be able to grip the rear end of the rod (26) engaged in the channel (74) in order to transmit to it a large traction force when the clamp (34) is moved in the direction of the rear end of the mounting (20),

      characterized

   in that the clamp (34) can be moved by the said drive means (42, 44) along the mounting (20) over a length which corresponds approximately to the length of the rod (26),

   in that a key (78) can be engaged in a housing (76) in the body (75) of the clamp (34) so as to block the channel (74) axially and to be able to transmit, to the rear end of the rod (26) engaged in the channel (74), an axial thrust force when the clamp (34) is moved in the direction of the front end of the mounting (20),

   in that the said key (78), when it is withdrawn from its housing (76), frees the channel (74) in the clamp (34) so as to be able to pass through this channel (74) with the drill bit (27) and to couple the latter to the coupling (30) of the drilling apparatus (32) located between the clamp (34) and the rear end of the mounting (20),

   in that intermediate guides (55i) are mounted on the mounting (20) between the front end of the latter and the clamp (34), the said guides (55i) having, on the mounting, operating positions in which they surround the rod (26) at several axially spaced-apart places during its insertion into the taphole blocked beforehand with the taphole clay, and parked positions in which they do not hinder the advance of the said clamp (34) towards the front end of the mounting (20), and

   in that these intermediate guides (55i) are capable of moving, as the clamp (34) advances towards the front end of the mounting (20), from the said operating positions into the said parked positions.
2. Machine according to Claim 1, characterized in that the said guides (55i) can slide on the mounting.
3. Machine according to Claim 2, characterized in that the said intermediate guides (55i) are mounted on the mounting (20) so as to be pushed by the said clamp (34) from their initial operating position to a parked position at the front of the mounting, as the said clamp (34) advances towards the front of the mounting (20).
4. Machine according to Claim 3, characterized in that each intermediate guide (55i) can be driven by the said drive means from the parked position at the front of the mounting (20) to its initial operating position, as the said clamp (34) retreats from the front towards the rear of the mounting (20).
5. Machine according to any one of Claims 1 to 4, characterized in that the said intermediate guides (55i) consist of hooks (56), sliding on the mounting (20) and provided with a lateral notch enabling the rod (26) to be housed therein, and in that the said lateral notch is provided with a component (58) enabling it to be closed laterally after the rod (26) has been housed therein.
6. Machine according to any one of Claims 1 to 5, characterized in that the said drive means mounted on the mounting (20) comprises at least one endless chain (44) installed on the mounting (20) and at least one drive motor (42) whose direction of rotation may be reversed.
7. Machine according to Claim 6, characterized in that the motor (42) is a hydraulic motor.
8. Machine according to any one of Claims 1 to 7, characterized

   in that the clamp (34) and the drilling apparatus (32) are supported by a common carriage (36) which can slide in rails (22, 24) of the mounting (20), and

   in that this carriage (36) is connected to the said drive means (42, 44).

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