EP0552476B1 - Apparatus for opening the taphole of a shaft furnace - Google Patents

Abstract

A machine and method is provided for piercing a taphole for a shaft furnace. The machine comprises a mounting, with a support installed on the mounting so as to support a rod at the front of the mounting, a rear support which can move on the mounting and is provided with means for being coupled to the rear end of the rod and a clamp mounted in a sliding manner on the mounting and designed to grip the rod at any place between the front support and the rear support. A powerful rotary motor installed at the rear of the mounting drives an endless chain installed axially in the mounting. A clamp attached to the endless chain moves during the insertion of the rod into the taphole clay by reversal of the direction of rotation of the motor in a to-and-fro motion between a position (B) at the front of the mounting and a position (A) which is located at a distance L from the position (B).

Description

The present invention relates to a machine for drilling a tap hole of a shaft furnace, designed for implementing the method of the lost rod in which, after having closed the tap hole with a plugging mass, pushes a metal rod into it, before it has completely hardened, and it is extracted at the appropriate time with a view to opening the tap hole. Said machine comprises a carriage with a support installed on the carriage so as to support the rod at the front of the carriage, a rear support movable on the carriage and provided with means for being coupled to the rear end of the rod and a clamp slidably mounted on the carriage and designed to grip the rod at any location between said front support and said rear support.

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

The working body of these machines must include a mandrel with 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 rod. of piercing lost.

Most often we preserve on these machines also the possibility of being able to use a drill with a drill bit either to reform or move the tap hole, or to work with a conventional drill bit when the lost rod cannot be used for a reason or a other.

However, a powerful striker, as it is used on these machines, is not without drawbacks. First, it imposes significant stresses and vibrations on the material, in particular on the coupling clamp with the rod, which is thereby 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.

Patent application EP 0 379 018 makes it possible to partially remedy these drawbacks by proposing a clever method of extracting the rod in several phases by a reciprocating movement of a clamp under the action of a jack. silent hydraulic. The pneumatic striker must therefore no longer be bi-directional, since it is no longer used for extraction, but it is, however, still necessary for an efficient and rapid installation of the piercing rod.

The disadvantages of the striker could encourage the removal of percussion during the introduction phase. One could for example consider subjecting the working member to a more powerful drive means to advance the working member coupled to the rod along the carriage in the direction of the tap hole and thus to penetrate in force and without vibrations the rod in the semi-hardened filling mass. Unfortunately, this attempt cannot be envisaged, because, given the length of the rod, a more powerful push, without striker, risks first of all causing a buckling of the rod and then its final blocking in a partially sunken position in the mass. undergoing rapid hardening.

A more ingenious solution is suggested in the Luxembourg patent application LU-87 915 filed on April 3, 1991. This patent application proposes a bi-directional clamp whose reciprocating movement back and forth, produced by a hydraulic cylinder 'before the lookout, is used for both the introduction and the extraction of the drill rod. This proposal therefore seems to be the optimal solution insofar as it eliminates the need for a noisy striker and clamp destroyer. A disadvantage of this machine is that the bi-directional clamp and the means which actuate it always operate in the region before the lookout. However, this region is a zone at risk of splashing when the molten jet escapes from the taphole after the extraction of the rod.

A solution which eliminates this disadvantage is proposed in the Luxembourg patent application LU-88 029 filed on October 31, 1991. The machine proposed in this patent application is characterized in that the first cylinder is itself slidably mounted on the 'carriage and that it is movable along it under the action of a second hydraulic cylinder. The extraction of the rod is no longer carried out by an alternating reciprocating movement of the clamp, but by a continuous movement of recoil of the latter under the combined action of the two hydraulic cylinders. The clamp is thus released from the area at risk of splashing at the front of the carriage before the molten jet escapes from the tap hole. In addition, the extraction is faster, since it is carried out by a continuous movement and no longer involves back and forth of the clamp.

The introduction of the piercing rod into the tap hole is however carried out according to the same process as that proposed in the Luxembourg patent LU-87 915; that is to say that the clamp performs an alternating back-and-forth movement under the action of the first jack, after the latter has been advanced into the operative position by the second jack.

This solution proposed in the Luxembourg patent application LU-88 029 gives complete satisfaction with regard to operation. Unfortunately, however, it leads to an appreciable increase in the size and in particular of the overall length of the machine, which is more than inconvenient given the shortage of space available around the shaft furnace.

The object of the present invention is to propose a machine for drilling a tap hole of a shaft furnace, designed for implementing the method of the lost rod in a manner analogous to that carried out with the machine on demand. Luxembourg patent LU-88,029, but which is distinguished by an overall length significantly reduced compared to the machine proposed in the Luxembourg patent application LU-88,029.

To achieve this objective, the present invention provides a machine for drilling a tap hole of the kind defined in the preamble and which is characterized by a powerful rotary motor installed at the rear of the carriage, by at least one chain. endless installed axially in the carriage between its front end and its rear end and driven by the rotary motor, by means for attaching the clamp to the endless chain so that it can be driven by the chain between the front end and the rear end of the mount and vice versa, and by means of control of the rotary motor to achieve during the introduction of the rod into the blocking mass by reversing the direction of rotation of the motor a movement of back and forth of the clamp between a position (B) at the front of the carriage and a position (A) which is located at a distance L from position (B), said distance L being less than the length of the rod.

According to the main feature of the present invention, a sliding clamp is attached to at least one endless chain installed axially in the mount. This chain is driven by at least one powerful motor, the direction of rotation of which can be reversed.

It should first of all be noted that the machine according to the present invention makes it possible to apply the method of introduction and extraction of the rod proposed in the Luxembourg patent application LU-88 029.

Thus the introduction of the piercing rod into the blocking mass is carried out by means of said rotary motor control means as follows:

After having threaded the piercing rod through the clamp and having coupled it with a sliding support at the rear of the carriage, the clamp is brought open by a rotation of the motor in a first direction at a certain distance L from l before the lookout, the clamp is closed and the rod is advanced using the clamp of said length L by rotating the motor in the same first direction, the clamp is then opened and the clamp is brought back again at the distance L from the front of the carriage by rotating the motor in the opposite direction, the clamp is closed and the rod is advanced a second length L.

This back and forth movement of the clamp over said distance L is repeated until the rod is pressed the desired length into the taphole.

It should be noted that said distance L is determined to avoid buckling of the rod during its introduction.

The extraction of the drilling rod is carried out as follows:

After having secured the end of the rod with the clamp located at the front of the carriage, it is removed by the chain, thus releasing the piercing rod in a continuous movement of the tap hole.

The clamp used is advantageously a bi-directional clamp of the kind described in the Luxembourg patent application LU-87 915 filed on April 3, 1991 and its addition certificate LU-88 020 filed on October 16, 1991.

The clamp may however also be a uni-directional clamp of the kind described in the Luxembourg patent LU-87 427, filed on January 16, 1989, but mounted in the opposite direction. This pliers is then used only to push the rod into the tap hole. In this case, the rear sliding support must be fitted with a second clamp intended for extracting the rod. This is for example a clamp as described in the Luxembourg patent LU-87 546, filed on June 30, 1989. During its recoil movement the first clamp, which is open, bears on the second clamp and pushes then said sliding support coupled to the end of the rod towards the rear, thus releasing the piercing rod from the tap hole.

A main advantage of the machine proposed by the present invention is its reduced length compared to a machine as described in the Luxembourg patent application LU-88 029. It will indeed be noted that the difference in length between the two machines corresponds approximately to the stroke of the reciprocating movement during the introduction of the rod, that is to say the length of the first hydraulic cylinder, installed behind a carriage supporting the clamp to produce said reciprocating movement come.

Another advantage is the reduced height of the machine proposed by the present invention. Indeed the chain can be easily integrated into the carriage, while the hydraulic cylinders proposed in the Luxembourg patent application No. 88 029 must for reasons of space be mounted on said carriage.

In a preferred embodiment, the machine proposed makes it possible to vary the stroke of the reciprocating movement used at the front of the carriage for the introduction of the rod. Thus this stroke can be freely chosen taking into account i) the buckling characteristics of the rods used and ii) the force necessary for the introduction of the rod. The stroke can for example be increased if a rod with a larger diameter is used (eg a rod of 50 mm instead of a rod of 40 mm in diameter). Similarly, the stroke can be reduced if it is known that the blocking mass has hardened, for a reason or a other, more than usual. It will moreover be appreciated that an increase in the stroke of said reciprocating movement reduces the time necessary for the introduction of the rod. Hence the advantage of not choosing a stroke that is too small and of adapting the stroke to the characteristics of the rod and of the blocking mass.

• les Figures 1 et 1a montrent schématiquement une section de face, respectivement une vue en plan d'une machine de perçage selon à la présente invention, en position de préparation pour l'introduction d'une tige dans la masse de bouchage;
• les Figures 2 et 2a montrent des vues analogues, juste avant le premier mouvement d'introduction de la tige;
• les Figures 3 et 3a montrent des vues analogues, juste après le premier mouvement d'introduction de la tige;
• les Figures 4 et 4a montrent des vues analogues, la machine étant équipée d'une mèche pour un forage classique.

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

• Figures 1 and 1a schematically show a front section, respectively a plan view of a drilling machine according to the present invention, in the preparation position for the introduction of a rod into the sealing mass;
• Figures 2 and 2a show similar views, just before the first movement of introduction of the rod;
• Figures 3 and 3a show similar views, just after the first movement of introduction of the rod;
• Figures 4 and 4a show similar views, the machine being equipped with a drill bit for conventional drilling.

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 see at the front of the carriage only the beam 20a, the beam 20b not being shown 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.

Reference 26 designates a piercing rod, also called a lost rod, for the method described above. This rod 26 is carried, at the front of the machine, by a support 52 which is preferably a sliding support, for example of the type described in patent GB 2,216,827.

However, it is also possible to use a fixed support of the type proposed by European patent application EP 0 064 644, this comprises two flaps mounted at the front of the mount 20 and which can pivot between an open position facilitating engagement and gripping the rod 26 with a view to extracting it and a position in which they define, between them, a passage opening and support for the rod 26. The two flaps thus constitute a support and form at the same time a splash protection shield from the jet of the tap hole.

At the rear, the rod 26 is supported by a second support which can follow the movement of the rod. It is for example a coupling 30 integral with a working member 32. This working member is supported by a carriage sliding freely along the mount 20, for example using rollers 33 moving along the outer sides of the two beams 20a and 20b of the carriage 20 (see Figure 1a).

This working member 32, which conventionally comprises a drill and a striker, is however no longer used in the lost rod process. Its presence on the lookout is justified in order to be able to drill, if necessary, a tap hole with a conventional drill bit. It follows that if conventional drilling is not necessary, or that this drilling can be carried out in another way, the working member 32 can in principle be omitted. It is then replaced by a simple sliding press which follows the movement of the rod 26 thus ensuring its support at the rear.

Reference 34 is a clamp, for example a bi-directional clamp of the kind proposed by the Luxembourg patent application LU-87 915 or in its application for addition patent LU-88 020. The opening and closing of the clamp are controlled by a pneumatic circuit (not shown). A carriage 36, mounted for example on pads 37 guided in the rails 22, 24 of the mount 20, serves as a support for the clamp 34.

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 control module represented diagrammatically by the reference 47.

The carriage 36 supporting the clamp 34 is fixed to the endless chain and can consequently 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 lookout 20 and vice versa.

We will now describe the operation of the machine for introducing the rod 26 into the taphole and for extracting it. Preferably the rod 26 is loaded into the machine when it is in the garage position and when the clamp 34 occupies a position at the rear of the mount as shown in Figure 1. The loading is carried out by threading the rod 26 through the clamp 34 open in the coupling-support 30 secured to the working member 32 and by coupling the support coupling 30 to the rear end of the rod 26.

When the rod 26 is in place (see Figure 1), the motor 42 is actuated by the control system 47 to rotate the chain in a first direction and thus advance the clamp 34 which is fully open in a position A (see Figure 2). The clamp 34 not being activated, it can slide freely with respect to the rod 26 which is held in the coupling 30 of the working member 32.

In principle it would be possible to advance the clamp 34 into said operative position A according to Figure 2 before loading the rod 26, but it is easier to engage the rod when the clamp 34 occupies a position at the rear of the carriage according to Figure 1.

From the position of Figure 2 can begin the process of introducing the rod 26 into the mass of the tap hole. This operation is carried out in principle according to the method proposed in the Luxembourg patent application LU-87 915. For this purpose, the motor 42 and the clamp 34 are activated simultaneously, which has the effect of i) closing the clamp 34 and ii) to move it from position A in Figure 2 to position B in Figure 3 by driving the rod 26 and the working member 32 integral with the rod. Arrived in position B, the direction of the hydraulic fluid supplying the motor is reversed, which has the effect of reversing the clamp by a rotation in opposite direction of the motor 42. At the same time the pneumatic circuit controls the opening of the clamp 34 During this return movement the rod 26 remains stationary, since the clamp 34 is open and can thus slide along the rod 26.

When the carriage 36 returns again to position A, the direction of the hydraulic fluid is reversed, that is to say that the direction of rotation of the motor 42 is reversed to cause the clamp 34 to move to position B in FIG. 3. At the same time, the pneumatic circuit controls the closing of the clamp 34. This to-and-fro of the clamp 34 between position A and position B is then repeated as many times as necessary to introduce the rod 26 of the desired length into the taphole.

The triggering of the reversal of the direction of rotation of the motor 42 and of the closing respectively opening of the clamp in positions A and B can for example be done using two limit switches, the first of which is associated with the stop 50 and the second is fixed on the carriage between the stop 50 and the stop 51. This second switch is shown schematically in Figures 2 and 3 by the reference 53. The distance L between the front stop (50) (= position B) and position A can then be varied by fixing the second limit switch at a greater or lesser distance from the stop 50.

One solution which eliminates the second limit switch is to use the signal from a tachometer 53 installed on the motor 42 to determine in a calculation unit 55 (cf. FIG. 1a) at any time the exact position of the carriage 36 on the carriage and for controlling, through the control module 47, the reversal of the direction of rotation of the motor 42 when the carriage passes at a point determined in advance. With such a calculation unit 55, it is preferable to use limit switch signals integrated in the stops 50 and 51 to automatically calibrate said calculation unit on each pass; that is to say to reset it and to recalculate the rectilinear displacement of the clamp 34 which corresponds to an entire revolution of the motor 42. When the motor 42 used to drive the chain 44 is a hydraulic motor, it is quite possible also understood to make flow measurements of the hydraulic fluid supplying the engine to determine the exact moment when the direction of rotation of the engine must be reversed, and when the clamp 34 must be open, respectively closed.

To extract the rod from the tap hole, the mount 20 is moved to the tap hole. The clamp 34 is moved by the motor 42 at the front of the carriage, against the stop 50. When the carriage is correctly positioned, the free end of the rod 26 engages through the clamp 34 which is open. The pneumatic supply circuit of the clamp 34 then controls the closing of the clamp 34. Now the motor 42 can withdraw via the chain 44 the carriage 36 supporting the clamp 34 towards the rear and thus extract the rod from the tap hole.

It should be noted that this time the passage of the carriage 36 in position A of Figure 2 does not in fact cause the clamp to be released and the direction of rotation of the motor to be reversed, but that the extraction continues all at once, in principle until the carriage 36 strikes against the stop 51, which advantageously causes an automatic engine stop.

It is interesting to note that for the extraction operation it is also possible to use the coupling 30 installed on the working member 32. This coupling 30 is then a clamp designed for the extraction of the rod, for example a clamp of the kind described in patent LU-87 546, and the clamp 34 may be a uni-directional clamp designed for the introduction of the rod 26, for example a clamp of the kind described in patent LU 87 427. In this case the clamp 34 remains open and the free end of the rod 26 crosses it to be gripped by the coupling / clamp 30. When it returns back the clamp 34 bears directly on the clamp 30 and the member of work in front of you. As a result, the working member must not transmit tensile force to the rod.

This variant brings first of all constructive advantages. Thus the construction of the clamp 34 becomes easier. In addition, it should only be connected to one pneumatic control circuit.

It will be noted that the carriage 36 can also be made integral supporting the clamp 34 and said member for work 32, for example by means of two hooks 60 and 60 'situated on each side of the working tool and capable of engaging automatically or manually with tenons 61 and 61' situated laterally on said carriage 36.

Thus the working member 32 does not need its own drive system on the carriage 20 to carry out, for example, drilling with a conventional drill 27 (cf. FIGS. 4 and 4a).

It will be appreciated that the present invention provides a machine which, by its multiple advantages over the state of the art, certainly brings substantial technical progress with regard to the execution of said method of the lost rod and contributes in particular to a better environmental protection by almost silent operation.

Claims (12)

1. Apparatus for opening the taphole of a shaft furnace, designed for the implementation of the embedded rod process in which, after having plugged the taphole with taphole clay, a metallic rod (26) is driven into the said clay before it has completely hardened, and the said rod is then extracted, at a desired moment, with a view to opening the taphole, the said apparatus comprising a mounting (20) with a support (52) installed on the mounting so as to support the rod (26) at the front of the mounting (20), a rear support (30) moveable on the mounting and fitted with means for coupling it to the rear end of the rod (26) and a clamp (34) mounted so that it slides on the mounting and designed to grip the rod (26) at any place between the said front support (52) and the said rear support (30), characterised by a powerful rotary motor (42) installed at the rear of the mounting (20), by at least one endless chain (44) installed axially in the mounting (20) between its front end and its rear end and capable of being driven by the rotary motor (42), by means for attaching the clamp (34) to the endless chain (44) so that it can be driven by the chain (44) between the front end and the rear end of the mounting (20) and vice versa, and by means for controlling the rotary motor (42) in order to produce, during the introduction of the rod into the taphole clay, by a reversal of the direction of rotation of the motor (42), a reciprocating movement of the clamp (34) between a position (B) at the front of the mounting (20) and a position (A) which is located at a distance L from position (B), the said distance L being less than the length of the rod (26).
2. Apparatus according to Claim 1, characterised by a pneumatic clamp (34) and a control module for the pneumatic clamp (34) designed for the automatic opening of the pneumatic clamp (34) in the said position (B) before the return to the said position (A) and for the automatic closing of the pneumatic clamp (34) in the said position (A) before the return to the said position (B).
3. Apparatus according to Claim 1 or 2, characterised in that the distance L is freely adjustable.
4. Apparatus according to Claim 1, characterised in that the said position (A) is defined by the installation of an end-of-travel switch on the mounting (20), the said switch being actuated by a component attached to the endless chain (44) when the clamp is at a distance L from the position (B).
5. Apparatus according to Claim 1, characterised in that the position of the clamp (34) is determined at each instant by a computer unit receiving as an input signal the output signal from a revolution counter installed on the motor (42) and in that the said distance L may be input as a reference value into the said computer unit.
6. Apparatus according to Claim 1, characterised in that the rotary motor (42) is a hydraulic motor.
7. Apparatus according to Claim 6, characterised in that the said means for controlling the rotary motor (42) comprise a device for prior adjustment of the quantity of hydraulic fluid supplying the rotary motor (42).
8. Apparatus according to Claim 1, characterised by a working mechanism mounted so that it slides on the mounting (20) and comprising a coupling member (30) so that it can be coupled to the rear end of the rod (26).
9. Apparatus according to Claim 8, characterised in that the working mechanism (32) comprises a drilling machine and a striking hammer.
10. Apparatus according to Claim 9, characterised in that the clamp (34) may be attached firmly to the said working mechanism (32), the latter then being driven by the clamp (34) attached to the chain (44).
11. Apparatus according to Claim 9, characterised in that the clamp (34) is a unidirectional clamp capable of being used to grip the rod (26) during the operation of introducing the said rod, in that the coupling member (30) attached firmly to the working mechanism (32) is a unidirectional clamp capable of being used to grip the rod and to transmit to it a tractive force, and in that the clamp (34) is equipped with means for pressing directly on the coupling member (30) during the operation of extracting the rod (26).
12. Apparatus according to any one of Claims 1 to 11, characterised in that the clamp (34) is a bidirectional clamp designed to grip the rod (26) in order to transmit to it both a tractive force and a thrust.

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