EP0573766A1 - Combination clamping chuck for a shaft furnace taphole piercing machine - Google Patents

Abstract

A combination chuck (32) is provided which makes it possible to transmit both a traction force to the end of a rod (48) and a torque (moment of rotation) to a drill (46) on a machine (10) for drilling a taphole. This combination chuck comprises a rotary body (34) mounted on the drive spindle (26) of a work member (18) which can slide on the drilling machine (10). A support structure (36) integral with the work member (18) forms a guide cage around the rotary body (34). Means for transmitting a traction force to the end of a rod (48) and a torque to a drill are arranged around a front cavity in the rotary body (34). <IMAGE>

Description

The present invention relates to a mandrel for transmitting both a tensile force at the end of a rod as a moment of rotation to a drill. It relates more particularly to a universal mandrel for a machine for drilling a tap hole of a shaft furnace, said drilling machine comprising a working member provided with a spindle defining a longitudinal axis O, said working member being mounted with a sliding carriage on the drilling machine and capable of generating at least one moment of rotation around the axis O and a tensile / percussion force along the axis O, said mandrel comprising an oblong body provided at one of these ends of means to be made axially integral with the spindle and at the opposite end of a front cavity arranged around the axis O to introduce therein an end of a drill, respectively of a rod drilling.

It is known that drilling the tap hole of a shaft furnace can be done either by normal drilling, or by the method of the lost rod.

During normal drilling, a drill is driven in rotation by a working member mounted on a mount which is aligned in the axis of the tap hole. This process therefore uses a rotating cutting tool, the drill, which is coupled to the spindle of the working member to make the taphole. Most often the drill is provided with an axial channel, which crosses it longitudinally and which makes it possible to send pressurized air to the head of the drill, in order to better evacuate the drilling debris and especially to cool the head of the drill. forest. The device used to couple the drill to the spindle can be a fairly simple, therefore fairly light, mandrel which is screwed onto the spindle of the working member and which allows a moment of rotation to be transmitted to the drill.

In the method of the lost rod, a metal rod is introduced into the taphole after having closed the taphole with a plugging mass and before the latter has completely hardened. If we want to open the tap hole, we extract the rod to make an opening in the hardened plugging mass.

For the extraction of the rod from the tap hole, it is known to equip the working member of a drilling machine with a special coupling device to secure the free end of the rod firmly with the working member and to transmit in this way to the rod an axial tensile force and most often the strikes of a striker forming an integral part of the working member.

Such special coupling devices are for example known by the Luxembourg patent LU-83 917, filed on February 3, 1982, respectively by the Luxembourg patent LU-87 546, filed on June 30, 1989. The two documents present clamps which can be screwed onto the threaded spindle of the working member. They comprise a body provided with a front bore intended to receive the free end of the drilling rod and two movable jaws which are arranged symmetrically around this front bore and which are displaceable under the action of pneumatic cylinders to grip said end free.

These pliers are however not suitable for transmitting a torque to a drill. Indeed, the rotation of the clamp to transmit an important moment to a drill caught between the jaws would inevitably damage the latter. It should also be borne in mind that such a clamp is cantilevered on the spindle of the working member, and that it weighs approximately 50 kg, that is to say that it is much more massive than the mandrel normally used to drive the drill. It therefore seems a priori excluded from rotate it at 150 rpm to drive a drill.

We also realized that the clamp was often subjected to off-center forces relative to the axis of the spindle when applying the lost rod process. However, these offset forces induce unacceptable bending moments in the spindle and in the mechanics of the working member.

To avoid this drawback, there has been proposed in the Luxembourg patent LU-87,010, filed on October 6, 1987, a mounting device in the form of a cage which makes it possible to rigidly fix a clamp, of the type of those described in the Luxembourg patents LU-83 917 and LU-87 546, on a carriage supporting the working member on the carriage. This cage blocks any rotation of the clamp and prevents the spindle from being subjected to a bending moment due to offset forces. In addition, the device of patent LU-87 010 facilitates mounting and dismounting of the clamp on the threaded spindle of the working member.

The ease of mounting the clamp is an important aspect, since the dismantling of the clamp must be carried out when the working member is to be used for working with a drill, and the reassembly of the clamp must be carried out at most late if you want to extract a drill rod from the tap hole using the same working member. Even with the mounting device of patent LU-87 010 this exchange of the pliers for a drill chuck and vice versa, remains a tedious manual labor, which still consumes a lot of time and which exposes the worker to the risk of accidents. .

The object of the present invention is to provide a very robust universal mandrel, which hardly transmits the offset forces to which it is subjected to the spindle and which makes it possible to transmit a tensile / percussion force at the end of a rod and a important moment of rotation to a drill.

This problem is solved by a universal mandrel for a machine for drilling a tap hole of a shaft furnace, said drilling machine comprising a working member provided with a spindle defining a longitudinal axis O, said working member being mounted using a sliding carriage on the drilling machine and capable of generating at least one moment of rotation around the axis O and a tensile / percussion force along the axis O, said mandrel comprising an oblong body provided at one of its ends with means to be made axially integral with the spindle and at the opposite end with a front cavity arranged around the axis O to introduce therein one end of a drill, respectively of a drilling rod. This mandrel is characterized by first means for gripping the end of a piercing rod in said cavity, these first means making it possible to transmit said tensile / percussion force to this rod and second means for blocking the end of a drill bit in said cavity, these second means making it possible to transmit a moment of rotation to this drill bit, said first and said second means being arranged in said body around said cavity, by a rigid structure, which is rigidly fixed to said sliding carriage and which s 'extends along said oblong body integral with the spindle, and by at least one bearing in this support structure which supports and guides said body radially while allowing a movement of rotation around the axis O and relative axial sliding of said body .

The mandrel according to the present invention makes it unnecessary to exchange the pliers used for extracting a drill rod for a drill chuck if, on a machine for drilling a tap hole, it is desired to drill said hole. casting with a rotating cutting tool. According to the present invention, it suffices to introduce the end of the drill bit into the front cavity of the body. and to block it with said second means which ensure the transmission of the moment of rotation to the drill. During the extraction of a drilling rod from a tap hole, the end of the latter is introduced into the same front cavity, where it is then gripped by said first means making it possible to transmit to this rod a force of pull / percussion.

According to an essential characteristic of the present invention, the rotary body, made integral with the spindle, is guided radially by at least one bearing mounted in a rigid support structure which is rigidly fixed to the sliding carriage of the working member. It is this assembly which allows the body to be rotated, comprising the first means for transmitting an axial tensile force to a drilling rod and the second means for transmitting a moment of rotation to a drill. This assembly also allows sufficient axial travel of the rotary body to transmit a percussion force.

In addition, this mounting gives sufficient rigidity to the mandrel, when the latter is used to apply the lost rod method. Indeed through said bearing, the offset forces, which appear especially when working with the piercing rod, are transmitted through the support structure to said sliding carriage and do not give rise to bending moments at spindle. It is recalled that such offset forces appear in particular when the drilling machine is withdrawn from the tap hole, while the rod is not yet entirely disengaged from the tap hole. However, such an early movement of the drilling machine from its working position to its garage position is often required, in particular in order to avoid the machine being subjected to splashes of the jet of molten metal, which is occur upon opening the tap hole.

It will be noted that the mandrel according to the present invention also eliminates a defect in the mounting device according to the patent LU-87 010. The latter blocks any rotation of the clamp although it is still possible to operate the working member to produce a moment of rotation. As a result, the spindle, and certain elements of the mechanics of the working member, are subjected to a maximum torsional force when the operator inadvertently triggers the rotational movement. This maximum torsional force is superimposed on the normal stresses which appear during the introduction and extraction of the rod, which leads to exaggerated fatigue of the elements of the working member.

In a preferred embodiment, said first means, transmitting said traction / percussion force to the piercing rod, comprise at least two movable jaws arranged symmetrically around the axis O and movable, under the action of jacks supplied with a pneumatic fluid, between a retracted position in which the distance between the jaws, measured perpendicular to the axis O, is greater than the greatest of the diameters of the rod and the drill and an advanced position, in which said distance is less than the diameter of the rod.

Preferably the longitudinal axes of the cylinders make an angle with the axis of rotation between 10 ° and 20 °, which allows to firmly grip the end of the rod, while reducing the diametrical size of the mandrel. Said jacks advantageously include a return spring which returns the jaws in the retracted position against a stop surface, in the absence of pneumatic pressure.

According to a preferred embodiment, said second means, transmitting said moment of rotation to the drill, comprise a transverse key, which is guided in transverse mortises arranged in said rotary body, and which cooperates with a flat formed in the end of the drill. It is a simple execution and effective of said second means for locking in rotation the end of the drill bit in said cavity.

In a preferred embodiment, the present invention provides a removable sleeve which is introduced axially into said cavity to lock the jaws in the retracted position against a stop. This sleeve, which is advantageously immobilized axially by said transverse key blocking the end of the drill in rotation, is intended to prevent the jaws from being able to move under the effect of striker strikes during drilling. Indeed, during drilling the jaws are subjected only to the action of the return spring which keeps them in the retracted position against a stop. However, the striker strikes cause a reaction on the jaws which, in the absence of the socket, would tend to project them, despite the existence of the return spring, on the end of the drill. This would result in hammering of the jaws and the jaws would be quickly damaged. It will be appreciated that this socket can also be advantageously used, when a piercing rod is introduced using the striker into the plugging mass. In this case the universal chuck serves only as a hammer transmitting the strikes from the striker on the end of the rod, which is simply introduced into said cavity without using said first means to grip the end of the rod. Another substantial advantage of this socket is that it effectively protects the jaws in the event that there is penetration of molten iron into said cavity. It should indeed be noted that when drilling the tap hole this risk is particularly high, because immediately after the drill has made the hole, the cast iron begins to spurt out of the latter and more or less significant splashes penetrate the inside said mandrel cavity, which is still close to the taphole. These splashes may then block the jaws. However, this risk is effectively eliminated by the use of said socket which is advantageously provided at one of its ends with a coaxial ring which radially closes said cavity around the drill.

In a preferred embodiment, said support structure, integral with said sliding carriage, forms a cage surrounding said rotary body over most of its length. This cage advantageously comprises a front plate and a rear plate, each provided with a socket. In these two sockets are adjusted respectively a first and a second cylindrical seat of said rotary body. These two sockets define said bearing in which the rotary body can rotate and slide axially using said first and second cylindrical bearing. The cage advantageously comprises slides which cooperate with a central cylindrical surface of said rotary body. This preferred execution of the mandrel is of a particularly simple construction while imparting sufficient rigidity to said mandrel, which effectively prevents damage to the spindle and the working member, even during the application of significant offset forces. In addition, this execution ensures excellent rolling conditions for the rotary body, and allows, if necessary, its axial sliding. Axial sliding of small amplitude of said rotary body is indeed necessary for the operation of a striker integrated in the working member.

Preferably the front plate is fixed by screws to the cage and can be removed to extract said rotary body from the cage. This feature allows easy maintenance of the chuck, since the rotary body can be easily exchanged for a spare rotary body, and the slides and bearing sleeves are easily accessible, which facilitates their rapid replacement.

The present invention also solves, in a preferred embodiment of the mandrel, the problem of feeding with a only pneumatic fluid supply line, either the pneumatic jaws of the jaws, or the drill. It is in fact recalled that during drilling, pneumatic fluid is used, conveyed through an axial channel in the drill at the head of the latter, as fluid for rinsing the tap hole and as coolant for the head.

This preferred execution of the mandrel which solves this problem comprises a supply channel for the pneumatic fluid communicating with a supply channel in the spindle, a first distribution channel for the pneumatic fluid to the jaws jacks, a second distribution channel for the pneumatic fluid opening axially into a surface of said cavity on which the end of the drill rests and a three-way valve integrated in said body and making it possible to communicate said supply line, either with the first distribution channel, or with the second distribution channel.

It will be appreciated by those skilled in the art that the present invention provides particularly simple embodiments of a three-way valve, which can be easily integrated into said rotary body to direct the pneumatic fluid, either to the jacks or towards the forest. It will be noted inter alia that the shutter surfaces in this three-way valve are essentially flat surfaces, which promotes obtaining a good seal with simple means.

The mandrel according to the present invention can also be advantageously used to rotate a rod when it is introduced into the stopper mass, before the latter has completely hardened. It has in fact been observed that this rotation of the rod during its introduction into the mass makes it possible to substantially reduce the axial force which must be applied to the rod in order to make it penetrate into the blocking mass. He will be noted that, in this case, the rod can be either held by the jaws, the torque to be transmitted for the rotation is indeed relatively low, or by the transverse key. The rotation can of course also be an oscillatory movement around the longitudinal axis of the rod.

• la Figure 1 représente une vue latérale d'une partie de l'affût d'une machine de perçage du trou de coulée d'un four à cuve, avec un organe de travail muni d'un mandrin universel selon l'invention;
• la Figure 2 représente une coupe par un plan vertical à travers l'axe dudit mandrin universel;
• la Figure 3 représente une vue selon les flèches (I) du mandrin universel, la plaque frontale est partiellement coupée;
• la Figure 4 représente une coupe selon la ligne de coupe (II) du mandrin universel de la Figure 2, certains éléments ont été enlevés pour permettre une vue à l'intérieur du corps du mandrin universel;
• la Figure 5 représente une coupe à travers une première exécution d'un robinet à trois voies intégré dans ledit mandrin universel;
• la Figure 6 représente une variante d'exécution du robinet de la Figure 5;
• la Figure 7 représente une coupe à travers une deuxième exécution d'un robinet à trois voies intégré dans ledit mandrin universel.

Other particularities and characteristics will emerge from the detailed description of a preferred embodiment presented below by way of illustration with reference to the appended figures, in which:

• Figure 1 shows a side view of part of the carriage of a machine for drilling the tap hole of a shaft furnace, with a working member provided with a universal chuck according to the invention;
• Figure 2 shows a section through a vertical plane through the axis of said universal mandrel;
• Figure 3 shows a view along the arrows (I) of the universal chuck, the front plate is partially cut;
• Figure 4 shows a section along the section line (II) of the universal chuck of Figure 2, some elements have been removed to allow a view inside the body of the universal chuck;
• Figure 5 shows a section through a first embodiment of a three-way valve integrated in said universal mandrel;
• Figure 6 shows an alternative embodiment of the valve of Figure 5;
• Figure 7 shows a section through a second embodiment of a three-way valve integrated in said universal mandrel.

Figure 1 shows a partial side view of the carriage 10 of a machine for drilling the tap hole of a shaft furnace. Along this carriage slides, via several rollers 12, 14, a carriage mobile 16 on which is fixed a working member 18. Most often the support carriage 16 is provided with its own drive means (not shown), for example an endless chain driven by a motor. The working member 18 comprises for example a member generating a moment of rotation, a front striker and a rear striker. A pin 26 serves as an external transmission member for the moment of rotation and the blows produced by said front and rear strikers 22, 24. This pin 26 comprises a threaded end 28 and an axial channel 30 (see FIG. 2), which constitutes a pneumatic fluid supply channel.

At the front of the carriage 16, that is to say on the side of the spindle 26, there is seen a preferred embodiment of a universal mandrel 32 according to the present invention. There is notably a rotary body 34 and a support structure 36 which is integral with the carriage 16 and which forms a sort of cage around the greater part of the rotary body 34.

The rotary body 34 is a body of revolution which comprises a front cylindrical surface 37 and a rear cylindrical surface 38, as well as a central cylindrical surface 40 which has a diameter slightly greater than the other two cylindrical surfaces (see FIG. 2). The rear cylindrical bearing surface 38 comprises a tapped blind hole 42, produced according to the rules of the art along the axis of revolution O to receive the threaded end 28 of the spindle 26 of the working member 18.

The front cylindrical bearing surface 37 has a first bore 44 coaxial with the axis of revolution O of the rotary body 34. This first bore 44 has a diameter substantially larger than that of a drill bit 46 or a rod 48 (cf. FIG. 1) which must be coupled to said mandrel 32. A second bore 50 which is blind, axially extends said first bore 44. The diameter of this second bore 50 is only slightly larger than the drill 46 and shank 48 diameters (see Figures 2 and 4).

In Figure 2 we see that in the first bore 44 is adjusted a sleeve 52 which is fixed by screws on said body 34. This sleeve 52 has at the bottom 56 of said first bore 44 a circumferential bead 58. This defines a transition surface 60 between said first bore 44 with a large diameter and said second bore 50 with small diameter, in order to facilitate the introduction of the end of the rod 48 or of the drill bit 46 into the second bore 50. It goes without saying that this transition surface 60 could also have been produced directly in the material of the body of revolution 34. A flat surface 62, perpendicular to the axis of revolution O, constitutes the bottom of the second blind bore 50. This flat surface 62 serves as an axial support for the drill 46 during drilling, respectively to the rod 48 when the latter is inserted into the blocking mass.

At the second bore 50 are arranged two notches 64, 64 '(see Figures 2 and 4), which are symmetrical with respect to a plane passing through the axis of revolution. In each notch slides a jaw 66, 66 '. Each of these jaws 66, 66 'is extended by a rod 68, 68', whose axis O 'preferably forms an angle between 10 ° and 20 ° with the axis of revolution O, in a bore 70, 70' made with the same angle in the median surface 40 of the rotary body 34. This bore 70, 70 'is closed axially by a threaded plug 72, 72'. The rod 68, 68 'ends with a piston head 74, 74' adjusted according to the rules of the art in the bore 70, 70 '. A helical spring 76, 76 'mounted between the piston head 74, 74' and a bearing surface 78, 78 'causes the rod 68, 68' to enter, in the absence of a pressurized pneumatic fluid, in the maximum 'bore 70, 70', that is to say until the jaw 66, 66 'is blocked by an axial abutment surface 80, 80' in its notch 64, 64 '. Springs helical 77, 77 'mounted in the plugs 72, 72' have the sole purpose of preventing the piston heads 74, 74 'from abutting against the plugs 72, 72' in the absence of the pneumatic fluid. An inclined surface 82, 82 ', radially delimiting each notch 64, 64', serves as a guide surface for the jaws 66, 66 ', when a pneumatic fluid under pressure is introduced upstream of the pistons 74, 74' to advance the jaws 66, 66 'from a retracted position to an advanced position.

It will be noted that the arrangement of the jaws 66, 66 'is made so that in the retracted position the distance between the jaws 66, 66' measured perpendicular to the axis of revolution O is greater than the largest of the diameters of the rods 48 and drills 46 used, and in the fully advanced position said distance is less than the smallest diameter of the rods 48 used. The jaws 66, 66 'are moreover provided, in a known manner, with a transverse edge 84, 84' for biting the piercing rod 48.

At the front, that is to say at the level of the first bore 44, the body of revolution 34, which is at this level a hollow cylinder, is provided, symmetrically to a plane passing through the axis of revolution O, two mortises 86, 86 '(see Figures 3 or 4). The latter are arranged so that a transverse key 88, which is guided in the two mortises 86, 86 ', comes to bear with one of its longitudinal surfaces 90 on a flat 92 made in the end of the drill 46. L the end of the drill 46 is thus immobilized in rotation and axially in the cavity formed by the first and the second bore 44, 50.

The reference 94 identifies a removable protective sleeve, the outside diameter of which is slightly less than the diameter of the second bore 50, and the internal diameter of which is slightly greater than the diameter of the end of the drill bit 46. This removable protective sleeve 94 is introduced in the second bore 50 so to axially lock the jaws 66 in the retracted position against the bearing surface 80 and thus to prevent them from being propelled forward during the operation of the striker. This socket 94 is advantageously provided at one of its ends with a coaxial ring 96 whose outside diameter corresponds to the inside diameter of the sleeve 52 (see Figures 2 and 3). It will be appreciated that this ring 96 facilitates the introduction of the sleeve 94 into the first bore 50 and makes it possible to block it axially by the same key 88 which is already used for locking in rotation the end of the drill bit 46. In addition, this ring 96 effectively prevents the penetration of splashes into the notches 64 and 64 'of the jaws. FIG. 4 indeed shows that in the absence of the protective sleeve 94 the notches 64 and 64 ′ are fully exposed to splashes of molten material which enter through the bore 44 in the rotary body 34.

The rotary body 34 is also provided with a pneumatic fluid distribution system. A supply channel 102 is arranged in the axis of revolution O of the rotary body 34 and opens into a chamber 104 which is axially delimited on one side by the threaded end 28 of the spindle 26 and on the other side by the bottom of the blind hole 42. It is recalled that this chamber 104 is supplied by the axial channel 30 arranged in the spindle 26. The axial supply channel 102 arranged in the rotary body is extended by a radial channel 106 towards a tap with three tracks 108 arranged in said median surface 40 of the rotary body 34 (see FIG. 5). It will be appreciated that this three-way valve 108 is fully integrated in said rotary body 34.

In a first embodiment (Cf Figure 5), this three-way valve comprises a cylindrical piston 110 which can slide in a blind bore 112 made, for example parallel to the axis of revolution O, in the central cylindrical bearing 40. A plug 114 screwed in the threaded mouth 116 of the bore 112 delimits the latter axially. The cylindrical piston 110 ends with a coaxial rod 118 of smaller diameter than the piston 110. This rod 118 crosses the plug 114 to extend the piston 110 outwards and thus serve as the control member of the three-way valve. Immediately behind the plug 114 is arranged in the bore 112 a first cylindrical chamber 120 into which opens a first distribution channel 122 which feeds the two jacks of the jaws 66, 66 '. At the opposite end of the bore 112 opens radially a second distribution channel 124 in a second chamber 126 defined in the bore 112 and axially limited on one side by the bottom 128 of the bore 112 and on the other side by a shoulder 130 of the piston 110. This second channel 124 is oriented radially towards the axis of revolution O, where it is extended by an axial channel 132 up to the level of the second axial bore 50. Here this axial channel opens into said flat end surface 62. The purpose of this second channel 132 is to make the end of the drill 46 communicate with the pneumatic fluid supply circuit, in order to be able to distribute this fluid through a channel 134 arranged axially in said drill 46 up to 'at the head thereof, where this fluid serves as flushing fluid and cooling fluid.

The pneumatic fluid supply channel 106 has its mouth 107 at the middle part of the bore 112. The cylindrical piston 110 is provided with an axial bore 136 which opens at the rod 118 in a cylindrical chamber 138 fitted in the plug 114 and which communicates axially with the chamber 120 into which the first distribution channel 122. opens. At the other end of the piston 110, the bore 136 opens axially in the cylindrical base of the piston 110. A longitudinal recess 140 is made in the piston 110 at the mouth 107 of the channel 106. This recess 140 is extended by a radial bore 142 in the axial bore 136 of the piston 110. Circumferential seals 144, 146, located on either side of this recess 140, prevent axial leaks between the piston 110 and bore 112, respectively in the first or second chamber 120, 126.

On the side of the first distribution channel 122, the communication between this channel 122 and the supply channel 106 is closed off at a shoulder surface 148 of the piston 110 and a front annular surface 150 of the plug. threaded 114. The shoulder surface 148 of the piston is provided with an annular seal 152. During the axial displacement of the piston 110 in the direction of the plug 114, the shoulder surface 148 abuts against the front annular surface 150 of the plug, which closes the cylindrical chamber 138, into which the axial pipe 136 of the piston opens, relative to the cylindrical chamber 120 into which the first distribution channel 122 opens.

The communication between the supply channel 106 and the second distribution channel 124 is closed at the cylindrical base of the piston and at the terminal plane surface which axially delimits the bore. To this end, the annular base 154 of the piston is provided with an annular seal 156. The axial insertion of the piston 110 into the bore 112 first opens the communication between the supply channel 106 and the first distribution channel 122 through the axial bore 136, the chamber 138 arranged in the plug 114 and the first chamber 120 into which the first distribution channel 122. The cylindrical base 154 of the piston abuts against the flat surface of the bottom 128 of the bore. This contact closes the communication between the supply channel 106 and the second distribution channel 124 through the axial bore 136 and the second cylindrical chamber 126 into which the second distribution channel 124 opens.

Figure 6 shows an alternative embodiment of the three-way valve of Figure 5. Instead of being actuated by a rod 118 in the axial extension of the piston 110, the three-way valve is actuated in the variant of Figure 6 by an eccentric disc 200 which comes to rest either on a first shoulder 202 or on a second shoulder 204, arranged in the piston 110. A pawl 206 provided with a spring 208 constitutes a means for locking the disc 200 and accordingly the three-way valve 108, either in the first position or in the second position.

Figure 7 shows a different embodiment of the three-way valve. This valve 210 comprises a rotary cylinder 212 provided with a first channel 214 formed by a diametral bore and a second channel 216 formed by two radial bores forming between them a right angle. The cylinder is adjusted in a blind bore 218 preferably made perpendicular to the axis of revolution O, in the central cylindrical bearing 40. An elastic ring 220 holds the cylinder 214 in this bore 218 while allowing it to rotate about its axis of revolution O. In a first position, the channel 214 communicates a branch 222 of the supply channel 102 with a branch 224 of the channel 132 supplying the drill and the channel 216 communicates the channel 122 supplying the jacks of the jaws 66, 66 '' via a channel 226 in the open air. In a second position, that is to say after a 90 ° rotation of the cylinder 212 in the clockwise rotation direction, the channel 214 no longer communicates the branch 222 of the supply channel with the branch 224 of channel 132, and channel 216 communicates channel 122 supplying the jaws jacks 66, 66 'with branch 222 of channel supply 102. A ratchet 230 provided with a spring 232 serves to lock the cylinder 212 in the two positions.

The rotary body 34 which has been described above, is supported and guided radially by the support structure 36 integral with the sliding carriage 16 (see FIG. 1), which supports the working member 18. Two bars 160, 162 with rectangular section extend overhang, on the side of the spindle 26, the sliding carriage 16 on each side of the carriage 10. At their free end the two bars 160, 162 are connected transversely by a first frame 164 and a second frame 166 rectangular. These frames 164, 166 are axially spaced and connected in this same direction by an angle 168 at each of the four corners (see Figure 4). These angles 168 delimit between the first and the second frame 164, 166 the four edges of a prismatic space with square cross section, the longitudinal axis of which coincides with the axis of rotation O of the spindle 26.

On the first and on the second frame 164, 166 are fixed respectively a first plate 176 and a second plate 178, so as to delimit said prismatic space axially (cf. FIG. 2). The first plate 176, that is to say the one which is furthest from the pin 26, is fixed by screws 177 to the front surface of the first frame 164 (see FIG. 3), while the second plate 178 can be either screwed or welded to the front of the second frame 166.

In the first plate and in the second plate are respectively made a bore 180 and a bore 182 coaxial with the axis O (Cf Figure 2). Each of these two bores 180 and 182 is provided with a socket 184, 186, which is preferably provided with a shoulder 185, 187 which comes to bear on the inner surface of the first plate 176 respectively of the second plate 178 The fixing of these sockets 184, 186 can be done, either by screwing, either by shrinking, gluing or any other suitable fixing method. The inside diameter of the socket 184 fixed in the first plate 176 corresponds to the diameter of the first cylindrical seat 36 of the rotary body 34. The inside diameter of the socket 186 fixed in the second plate 178 corresponds to the diameter of the second cylindrical seat 38. The adjustment of the diameters is chosen so as to allow rotation of the rotary body 34 under the effect of the rotation member 20, and a sliding of the latter in the axial direction under the effect of the striker 22, 24, while taking into account that the drilling machine must operate under harsh conditions. By way of information, it will be further specified that, on a machine for drilling a tap hole, the speed of rotation corresponds to approximately 150 revolutions per minute, while the stroke of the sliding movement corresponds to approximately 5 cm.

The central cylindrical surface 40 of the rotary body 34 is guided by four slides 190 fixed, for example by means of screws on the four angles 168. Alternatively the four slides 190 can however also be fixed by screws 191 to the plates 176, 178 , which facilitates their disassembly. Each of these slides 190 naturally has a sliding surface 192 which matches the outer cylindrical surface of the central surface 40 of the rotary body 34 on a longitudinal angular segment.

It is obvious to those skilled in the art that the present invention could also be achieved by providing the support carriage 16 of the working member 18 with a support structure comprising a robust sleeve, the longitudinal axis of which coincides with the axis of the spindle. This sleeve could then support a cylindrical rotary body having a constant diameter over its entire length (variant not shown in the figures).

It will however be appreciated that the execution of the mandrel described above using the figures has the advantage of being of particularly simple construction, of facilitating the replacement and maintenance of the rotary body and of the sliding surfaces, of guaranteeing good absorption of the off-center forces relative to the axis of the spindle and nevertheless guaranteeing low rolling and sliding resistance of the rotary body 34 in the support structure 36.

Claims (14)

Universal mandrel (32) for a machine for drilling a tap hole of a shaft furnace, said drilling machine comprising a working member (18) provided with a spindle (26) defining a longitudinal axis (O) , said working member (18) being mounted by means of a sliding carriage (16) on the drilling machine and capable of generating at least one moment of rotation (1) around the axis (O) and a force percussion / traction (2) along the axis (O), said mandrel comprising an oblong body (34) provided at one of its ends with means for being made axially integral with the spindle (26) and at the end opposite of a front cavity arranged around the axis (O) to introduce one end of a drill (46), respectively of a drilling rod (48) and being characterized by first means for gripping the end d 'a piercing rod in said cavity, these first means making it possible to transmit said percussion / traction force to this rod, and second means for locking the end of a drill in said cavity, these second means making it possible to transmit a moment of rotation to this drill, said first and second means being arranged in said body (34) around the front cavity, and by a rigid support structure (36), which is rigidly fixed to said sliding carriage (16) and which extends along said oblong body (34), and by at least one bearing in this support structure (36) which supports and radially guides said oblong body (34) while allowing a rotational movement about the axis (O) and relative axial sliding of said body (34). Chuck according to claim 1, characterized in that said first means, transmitting said tensile force to the drilling rod, comprise at least two movable jaws (66, 66 ') arranged symmetrically around the axis (O) and movable under the action of cylinders, supplied with pneumatic fluid, between a position retracted, in which the distance between the jaws measured perpendicular to the axis (O) is greater than the largest of the diameters of the rod and the drill, and an advanced position, in which said distance is less than the diameter of the rod. Chuck according to claim 2, characterized in that the longitudinal axes of the cylinders make an angle between the axis (O) between 10 and 20 °. Chuck according to claim 2 or 3, characterized by helical springs (76, 76 ') mounted in said cylinders and whose action is opposed to the action of the pressurized pneumatic fluid supplying these cylinders. Chuck according to any one of claims 1 to 4, characterized in that said second means, transmitting said moment of rotation to the drill, comprise a transverse key (88) which is housed in transverse mortises (86, 86 ') in said body (34) and which cooperates with a flat (92) made in the end of the drill (46) to block the latter in rotation in said cavity. Chuck according to claim 2, 3 or 4, characterized by a removable sleeve (94) which is introduced axially into said cavity to lock the jaws in the retracted position against a stop. Chuck according to claims 5 and 6, characterized in that the sleeve (94) is provided at one of its ends with a coaxial ring (96) which radially closes said cavity around the drill and which is immobilized axially therein by said transverse key (88). Chuck according to any one of Claims 1 to 7, characterized in that the said rigid support structure (36) forms a cage surrounding the said oblong body over most of its length, in that the said cage comprises a front plate ( 176) and a rear plate (178) each provided with a socket (184, 186) and in that said body (34) is provided at each of the sockets of a cylindrical seat (36, 38) coaxial with the axis (O). Chuck according to claim 8, characterized in that said front plate (176) is fixed by screws (177) on the cage and can be removed to extract said rotary body (34) from said cage. Chuck according to claim 8 or 9, characterized by four slides (190) mounted between the front plate (176) and the rear plate (178) and by a third cylindrical bearing (40) of said body (34), which is coaxial with the 'axis (O) and which has a larger diameter than the other two cylindrical surfaces (36, 38), said slides (190) radially guiding this central cylindrical surface. Chuck according to claim 2, characterized in that said rotary body comprises a supply channel (102, 106) for the pneumatic fluid communicating with a supply channel (30) in the spindle, a first distribution channel (122) pneumatic fluid to the jaws jacks, a second distribution channel (124, 132) of the pneumatic fluid opening axially into a surface (62) of said cavity on which the end of the drill (46) is supported and a three-way tap tracks (108) integrated into said rotary body (34) and making it possible to communicate said supply line (102, 106), either with the first distribution channel (122) or with the second distribution channel (124). Mandrel according to claim 11, characterized in that the three-way tap (108) comprises a cylindrical piston (110) which can slide axially between a first position and a second position in a bore (112) made in said body (34), the piston (110) being provided with an axial bore (136) communicating said supply channel (102, 106) in said first position with a first chamber (120) into which opens the first distribution channel (122) and in said second position with a second chamber (126) into which the second distribution channel (124) opens. Chuck according to claim 11 characterized in that the three-way tap (210) comprises a cylinder (212) which can be turned about its axis (O) in a bore (218) made in said body (34) between a first position and a second position, the cylinder being provided with internal channels communicating said supply channel (102, 222) in the first position with the first distribution channel (122) and in the second position with the second distribution channel (124 ). Mandrel according to any one of Claims 1 to 12, characterized in that the mandrel is used to communicate to the piercing rod a moment of rotation when the latter is introduced into the taphole before the hardening of a plugging mass with which the tap hole was closed.

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