GB2095381A

GB2095381A - Tap hole drilling machine

Info

Publication number: GB2095381A
Application number: GB8207034A
Authority: GB
Original assignee: Dango and Dienenthal Maschinenbau GmbH
Current assignee: Dango and Dienenthal Maschinenbau GmbH
Priority date: 1981-03-21
Filing date: 1982-03-10
Publication date: 1982-09-29
Also published as: FR2502175A1; IT1150320B; DE3111260C2; ATA97082A; IT8220177A0; DE3111260A1; AT377005B; FR2502175B1; JPS57164902A; JPH0137445B2; GB2095381B; LU84024A1

Abstract

A tap hole drilling machine has a hammer drill (2) guided on a mount (1) which is adapted to be swung into the working position and out of it and serves to move a tapping bar (5) towards and away from a furnace (3). A guide (6) for the bar (5) is provided at the furnace end of the mount (1), and an additional supporting device (8) for the bar (5) is slidably guided or fixedly mounted on the mount (1) and controlled by the working sequence of the tap hole drilling machine so that in the most forward position (close to the furnace) of the hammer drill (2) it releases the bar (5) and on withdrawal of the bar (5) provides support below the bar to prevent the tool holder of the hammer drill being subjected to high stresses. <IMAGE>

Description

SPECIFICATION Tap hole drilling machine The invention relates to tap hole drilling machines the hammer drill of which is guided on a mount adapted to be swung into the working position and out of it and serves to move a drilling, percussion or tapping bar, a guide for the bar being provided at the furnace end ofthe mount Tap holes of metallurgical furnaces, in particular blast furnaces, have heretofore been opened by drilling by means of a drilling bar or by preliminary drilling by means ofthe drilling bar and subsequently breaking through the remaining wall with a percussion bar.In the process, it is true, the tools coming into contact with the liquid furnace contents are shortened by burning or melting away, but as a rule even after retraction of the hammer drill into its starting position remote from the furnace they are supported by a guide located at the furnace end of the drilling mount.

In a more recent method, the tap hole is no longer drilled open. Instead, at a certain time after the plugging of the tap hole, a steel bar (hereinafter called a "tapping bar") is driven forward into the interior of the furnace by means of the hammer drill, which is in the form of a counter-blow hammer, and is withdrawn again at the time of the tapping operation by the hammer drill (counter-blow hammer), which then operates in the rearward direction.

The tapping bar must be of such a length that it is certain to reach the interior of the furnace. As a rule, it will therefore project a certain amount beyond the length of the tap hole into the interior of the furnace.

During the time until tapping takes place, this projecting portion of the tapping bar melts away, so that the tapping bar is shortened by this portion. On withdrawal of the tapping bar, the counter-blow hammer drill is retracted into its rear end position.

Before this end position is reached, the shortened tapping bar drops out of the guide at the furnace end of the drilling mount. As a consequence, the gripping device for coupling the tapping bar to the hammer drill, the hammer drill as a whole and, above all, the tool holder projecting from the hammer drill or located inside it are subjected to inadmissibly high stresses by the dead weight of the tapping bar, so that damage to these parts, generally in the form of repeated-stress or fatigue fractures, is the result.

Suitable strengthening of the hammer drill is excluded for economic reasons and also because of the greater amount of space required. It is true that by increasing the distance between the furnace breast and the front guide on the mount it would be possible to ensure an additional support up to a certain burn-off length, butthe precision of the initial drilling or of the application of the tapping bar at the desired point is impaired by increasing this distance and, moreover, the amount of space required for the entire assembly in the casting house is inadmissibly increased. It would also be conceivable to stop the retracting movementofthe hammer drill atthe instant when the front end of the tapping bar has left the tap hole.In practice, however, this cannot be carried out, since the operator does not know the actual length of the burnt-away tapping bar and, in view of the necessarily small distance between the mouth of the tap hole and the bar guide at the front end of the mount, cannot react quickly enough.

The problem underlying the invention is to solve the described problem with relatively simple constructional means and without additional space being required.

According to the invention, this is done basically by means of an additional supporting device for the bar.

According to a first embodiment of the invention, the additional supporting device is slidably guided on the mount, this device being so coupled to the hammer drill that its sliding movement is controlled by the advancing movement of the hammer drill, the arrangement being such that the distance between the supporting device and the hammer drill in the most forward position of the latter is a minimum and is a maximum on retraction of the hammer drill.

Suitably, the supporting device has a carrier arm which can be swung in and out below the drilling, percussion or tapping bar. Moreover, the carrier arm on the supporting device may be mounted to be swingable about an axis substantially perpendicular to the longitudinal axis of the mount.

Advantageously, the arrangement coupling the supporting device with the hammer drill controls the swinging movement of the carrier arm in such mannerthat in the most forward position of the hammer drill the carrier arm is swung out and on retraction of the hammer drill the carrier arm is swung in.

A particularly advantageous development of the first embodiment consists in that the supporting device is coupled to the hammer drill via control rods arranged parallel to the longitudinal axis of the mount and movable between suitably arranged stops both relative to the supporting device and relative to the hammer drill, and that one of the control rods is coupled to the carrier arm via a forked lever for carrying out the swinging movements of the arm.

According to a second embodiment, the additional supporting device is installed fixedly on the mount and has a swingable carrier arm. Again, the carrier arm for the drilling, percussion or tapping bar to be supported may be mounted to be swingable in and out about an axis substantially perpendicular to the longitudinal axis of the mount and the swinging movement of the carrier arm can be controlled via a cam roller by a straight actuating bar fixed to the hammer drill. A return spring is suitably provided for swinging the carrier arm inward into the initial or supporting position. The swinging in and out of the carrier arm may also, however, be produced by a positive or mating connection between the cam roller and the straight actuating bar.

Avariant of the second embodiment consists in that the carrier arm is mounted to be swingable about an axis substantially parallel to the longitudinal axis of the mount.

Again, the swinging movement of the carrier arm can be controlled via a cam roller by a control rail fixed to the hammer drill, it being possible for the inward swinging movement of .:e c.rnerarm into the supporting position to be assisted by it3 own weight and/or a spring.

Instead of the purely mechanical controls for the additional supporting device which have been mentioned so far, it is also possible to provide a pressure medium cylinder (pneumatic or hydraulic) controlled by the movement or position of the hammer drill for carrying out the swinging movements of the carrier arm, or the swinging movements of the carrier arm may take place by means of an electric adjusting drive.

The invention provides an additional supporting device on a tap hole drilling machine which satisfies the following conditions in an advantageous manner, reference being made to Figs. 1 and 2 of the drawing: 1) On retraction of the tapping barofthe original length Land shortened by the amount AL by burning away, it prevents overloading of the hammer drill and of the gripping device for the tapping bar when it slips out of its front guide on the mount by supporting the bar at a sufficient distance SL (= supporting length) from the hammer drill at the moment of release of the front end of the tapping bar; 2) it ensures the unimpeded forward and backward movement of the hammer drill over the entire length of advance V;; 3) moreover, it renders possible a free swinging of the whole tap hole drilling machine upwardly and away after the driving-in of the tapping bar (see arrows in Figs. 1 and 2); 4) the distance A of the front end of the drilling mount from the mouth of the tap hole is not increased by it; 5) the opening and closing of the additional supporting device occurs automatically in unison with the working sequence of the tap hole drilling machine.

Since the problem underlying the invention and the basic solution thereof have been made clear with reference to Figs. 1 and 2, practical embodiments of the invention will now be explained with the aid of Figs. 3 to 9 of the drawing. In the drawing: Fig. 3 is a diagrammatic side view and Fig. 4 is a plan view of a first embodiment; Fig. 5 is a plan view of a second embodiment; Fig. 6 is a view in the direction of the arrow VI in Fig. 1 (sic); Fig. 7 is a section on the line VII-VII in Fig. 6, parts having been omitted; Fig. 8 is a view, similar two Fig. 6, of a modified form of the second embodiment in the direction of the arrow VIII in Fig. 9, a part being shown separately in side view in Fig. 8a, and Fig. 9 is a plan view of the embodiment according toFig.8.

The reference symbols used in the following description have also been entered in Figs. 1 and 2, insofar as the parts designated thereby are shown diagrammatically in these Figures.

The tap hole drilling machine consists essentially of a drilling mount 1 which can be swung upwardly and away in known manner (see also the arrows in Figs. 1 and 2). A hammer drill 2 in the form of a counter-blow hammer is slidably guided on the mount 1 and has at its end facing the furnace 3 (Figs.

1 and 2) a gripping device 4 for receiving a tapping bar 5. A drilling or percussion bar may also be clamped in instead of the tapping bar 5, but in the following mention is made only of the tapping bar 5, since the problem to be solved here occurs chiefly with this. At the furnace end of the mount 1 there is a guide 6 for the tapping bar 5. The guide 6 can be opened when, the tapping bar 5 having been driven into the tap hole 7 (Fig. 2) of the furnace 3, the entire tap hole drilling machine is to or must be swung upwardly and away in order to remove it as quickly as possible over the pouring channel or runner still filled with hot iron.

Moreover, an additional supporting device 8 for the tapping bar 5 is slidably guided on the mount 1 and has a carrier arm 9 which can be swung in and out belowthe tapping bar 5 and is mounted to be swingable about an axis 10 substantially perpendicularto the longitudinal axis of the mount 1. The carrier arm 9 is mounted fixedly on a shaft at whose upper end a forked lever 11 is secured.

The hammer drill 2 and the additional supporting device 8 are coupled to one another via control rods 12, 13 extending parallel to the mount 1 and which are mounted to be freely movable in stops or shoulders 14 of the hammer drill 2 and in stops or shoulders 15 of the supporting device, the relative movements, however, being controlled in length and direction by suitable stops 16, 17, 18, 19, as explained hereinafter.

As shown in Fig. 3, the hammer drill 2 has arrived in its end position in front of the furnace 3 and has adopted its minimum distance c from the additional supporting device 8. The carrier arm 9 of the supporting device 8 has already been swung out beforehand and has cleared the way for the hammer drill 2 or at least for its gripping device 4. The tapping bar 5 has been driven into the furnace 1 (sic). After release of the gripping device 4 from the tapping bar 5 and opening of the front guide 6, the tap hole drilling machine can be swung upwardly and away, since the carrier arm 9 of the supporting device 8 has also released the tapping bar 5 in this position of all the movable parts.

The retraction of the tapping bar 5 from the tap hole 7 of the furnace 3 is best explained with reference to Fig. 4: To initiate the tapping operation, the tap hole drilling machine is first brought into the position shown in Fig. 3, the gripping device 4 of the hammer drill 2 is matingly coupled to the tapping bar 5 and the guide 6 at the furnace end of the mount 1 is closed. On commencement of the withdrawing movement of the hammer drill 2, which draws the tapping bar 5 back with it in the process, the additional supporting deviceistill remains at a standstill at first and its carrier arm 9 still remains swung out (position shown in chain-dotted lines in Fig. 4) until the stops 14 on the hammer drill 2 reach the stops 16 of the control rods 12, 13. These control rods 12, 13 are then carried along by the amounta, a driver 20 on the stop 19 of the control rod 13 swinging the forked lever 11 through about 90" out of the position 11' and thereby swinging the carrier arm 9 of the supporting device 8 in belowthetapping bar 5. At this instant, the predetermined maximum supporting length SL=a+b+c has been reached. (In accordance with Fig. 3, the amount is the distance of the gripping device 4 from the centre of the carrier arm 9). On further retraction of the hammer drill 2, the supporting device 8 is now also carried along, sliding on the mount 1, since the stops 19 of the control rods 12, 13 have reached the stops 15 on the supporting device.The tapping bar 5, shortened by the amount AL (Fig. 1), can now readily slip out of the guide 6 without loading the hammer drill 2 and the gripping device 4 additionally in an inadmissible manner. As soon as the tapping bar 5 has left the tap hole 7, the entire tap hole drilling machine is swung out of the jet of liquid iron, that is it is swung upwardly and away. With a tapping bar 5 which is not additionally supported, these movements would release mass inertia forces which could scarcely be absorbed by the gripping device 4 and the hammer drill2.

When a fresh (unshortened) tapping bar 5 is driven in, the procedure is as follows: The tapping bar 5 is clamped in the gripping device 4. At this time, the hammer drill 2 is in its end position remote from the furnace 3 (approximately as in Fig. 2). The relative positions of the hammer drill 2 and the additional supporting device 8 are as shown in Fig. 4, in which, however, the hammer drill 2 is not in its end position remote from the furnace 3, but is at a point from which the additional supporting device 8 is carried along via the control rods 12, 13. The fresh tapping bar 5 lies in the guide 6 at the front (furnace) end of the mount 1, because in fact it now has its unshortened original length L (Fig. 1).On the advance of the hammer drill 2 which now takes place, the tapping bar 5 is driven into the tap hole 7 which has been plugged a certain time beforehand. In this advancing movement of the hammer drill 2, it is not critical over a distance of advanceb howthesupporting device 8 behaves. If its frictional contact with the mount 1 is greater than the frictional contact between the tapping bar 5 and the swung-in carrier arm 9, then at first the supporting device 8 remains stationary. it may be that the control rod 12 moves at first with the hammer drill 2 until its stop 18 abuts the stop 15 of the supporting device 8.Should the supporting device 8 thereby already get into motion, this is of no importance, even if the friction conditions were to take such a form that the carrier arm 9 would already be swung out now, since on the driving-in of the tapping bar 5 the additional supporting device 8 does not anyway need to carry out its supporting function. It is most highly improbable, however, that a swinging-out of the carrier arm 9 will already take place along the distance of advance b.This happens with certainty, however, when the stops 14 of the hammer drill 2 have reached the stops 17 and then carry along the control rods 12, 13, but at least now also the control rod 13, because the hammer drill has now approached so close to the supporting device 8 that it becomes time to swing the carrier arm 9 out, so that it clears the way for the hammer drill 2. The distance of advance a is available for this swingingout of the carrier arm 9. After the distance of advance a has been covered, the supporting device 8 is now also carried along via the stops 17, 18 on the control rods 12, 13, and in fact as far as end stops 21 on the mount 1 (Fig. 4), so that the entire assembly is now in the end position close to the furnace (as is also shown in Fig. 1).It is now only still necessarytoopen the front guide 6 in order to be able to swing the entire tap hole drilling machine upwardly and away until the next tapping operation.

Figs. 5 to 9 show an embodiment in which the additional supporting device 8' or 8" is mounted fixedly on the mount 1 at a predetermined point. Figs. 5 to 7 show such a supporting device 8' with a carrier arm 22 which, like the carrier arm 9 in Figs. 3 and 4 is mounted fixedly on a shaft 23 rotatable about an axis extending substantially perpendicularly to the longitudinal axis of the mount 1. Disposed on a hub 24 of the carrier arm 22, the hub being fixed to the shaft 23, is a roller lever 25 with a cam roller 26 which cooperates with a straight actuating bar 27 fixed to the hammer drill 2. A bearing 28 for the shaft 23 is fixed on the mount 1 by way of a bridge 29.On approach of the hammer drill 2 to the supporting device 8' in the direction of advance, the carrier arm 22 is swung out below the tapping bas 6 through about 90 into the position 22' (Figs. 5 and 7) by the straight actuating bar 27 via the cam roller 26 and the roller lever 25, so that the way is clear for the further advance of the hammer drill 2. After the tapping bar 5 has been driven in, as described with reference to Figs. 1 to 4, the entire tap hole drilling machine can also be swung upwardly and away in the case of the embodiment of Figs. 5 to 7, after the front guide 6 (Figs. 1 to 4) has been opened.

When the hammer drill 2 has passed the supporting device 8' during its withdrawing movement, the straight actuating bar 27 releases the roller lever 25, so that a return spring 30, which is attached on the one hand to a lever 31 likewise fixed to the shaft 23 and on the other hand to an eye 32 on the bridge 29, can swing the carrier arm 22 in below the tapping bar 5, as shown in Fig. 6. Instead of a return spring 13 (sic), a positive working connection (not shown) may also be provided between the cam roller 26 and the straight actuating bar 27 for the swinging-in of the carrier arm 22. The entire working sequence is otherwise the same as that described with reference to Figs. 1 to 4.

Figs. 8 and 9 show another embodiment of a supporting device 8" arranged fixedly on the mount 1, wherein a carrier arm 33 is fixed to a shaft 34 which is mounted to be rotatable about an axis extending substantially parallel to the longitudinal axis of the mount 1 in bearings 35 on a bridge 36 fixed to the mount and receives at one end directed towards the furnace, and fast in rotation with it, a hub 37 of the carrier arm 33 and is connected at the other end remote from the furnace, and fast in rotation with it, to the hub 38 of a roller lever 39 with a cam roller 40.

A control rail 41 bent according to the intended swinging movement of the roller lever 39 is fixed to the hammer drill 2 and, on approach of the hammer drill 2 to the supporting device 8" in the direction of advance, swings the carrier arm 33 upwardly out of the room for movement of the hammer drill 2, as shown in Fig. 8. Fig. 8CI g~,a-f,s set el, in side view, taken from Fig. 8, the shape of an iortant part of the control rail 41. The control Fai; :1 may be a bent pipe or other bar material of round crosssection.On the withdrawing movement of the hammer drill 2, the carrier arm 33 is swung into the supporting position again by its own weight in accordance with the shape of the control rail 41, since the position of the centre of gravity of the carrier arm 33 forms a sufficiently large lever arm with respect to the axis of rotation of the shaft 34 and consequently, with the weight of the carrier arm 33, supplies a sufficiently large torque for the swinging-in movement.

A return spring (not shown) may Elso be provided in addition. Similarly to the length a in Fig. 4, the length a in Figs. 8a and 9 corresponds approximately to the control distance for the swinging of the carrier arm 33.

Although the described purely mechanical controls for the additional supporting devices 8, 8', 8" are preferred on account of their robustness and reliability, the scope of the invention is not exceeded even if hydraulic or pneumatic cylinders or electric adjusting drives which are controlled automatically in accordance with the working sequence are used in their place.

Claims

1. Tap hole drilling machine, the hammer drill og which is guided on a mount adapted to be swung into the working position and out of it and serves to move a drilling, percussion or tapping bar, a guide for the bar being provided at the furnace end of the mount, characterised by an additional supporting device (8,8', 8") for the bar (5).

2. Tap hole drilling machine according to claim 1, characterised in that the additional supporting device (8) is slidably guided on the mount (1).

3. Tap hole drilling machine according to claim 1 or 2, characterised in thatthe supporting device (8) is so coupled to the hammer drill (2) that its sliding movement is controlled by the advancing movement of the hammer drill (2), the arrangement b 3ing such that the distance between the supporting device (8) and the hammer drill (2) in the most forward position of the latter is a minimum (c) and is a maximum (SL) on retraction of the hammer drill (2).

4. Tap hole drilling machine according to any one of claims 1 to 3, characterised in that the supporting device (8) has a carrier arm (9) which can be swung in and out below the drilling, percussion or tapping bar (5).

5. Tap hole drilling machine according to claim 4, characterised in that the carrier arm (9) on the supporting device (8) is mounted to be swingable about an axis (10) substantially perpendiculartothe longitudinal axis of the mount (1).

6. Tap hole drilling machine according to any one of claims 1 to 5, characterised in that the arrangement (11-19) coupling the supporting device (8) with the hammer drill (2) controls the swinging movement of the carrier arm (9) in such manner that in the most forward position of the hammer drill (2) the carrier arm (9) is swung out and on retraction of the hammer drill (2) the carrier arm (9) is swung in.

7. Tap hole drilling machine according to any of .e or claims 1 to 6, characterised in that the sup- porting device (8) is coupled to the hammer drill (2) via control rods (12, 13) arranged parallel to the longitudinal axis of the mount (1) and movable between suitably arranged stops (16-19) both relative to the supporting device (8) and relative to the hammer drill (2), and one (13) ofthe control rods (12, 13) is coupled to the carrier arm (9) via a forked lever (11) for carrying out the swinging movements of the arm.

8. Tap hole drilling machine according to claim 1, characterised in that the additional supporting device (8f, 8") is installed fixedly on the mount (1) and has a swingable carrier arm (22, 23).

9. Tap hole drilling machine according to claim 8, characterised in that the carrier arm (22) forth drilling, percussion or tapping bar (5) to be supported is mounted to be swingable in and out about an axis (shaft 23) substantially perpendicular to the longitudinal axis of the mount, and the swinging movement of the carrier arm (22) is controlled via a cam roller (26) by a straight actuating bar (27) fixed to the hammer drill (2).

10. Tap hole drilling machine according to claim 8 or 9, characterised in that a return spring (30) is provided for swinging the carrier arm (20) (sic) inward into the initial or supporting position.

11. Tap hole drilling machine according to claim 8 or 9, charactensed in that the cam roller (26) is positively connected to the straight actuating bar for swinging the carrier arm (22) in and out.

12. Tap hole drilling machine according to claim 4, characterised in that the carrier arm (33) is mounted to be swingable about an axis (shaft 34) substantially parallel to the longitudinal axis of the mount (1).

13. Tap hole drilling machine according to claim 12, characterised in that the swinging movement of the carrier arm (33) is controlled via a cam roller (40) by a control rail (41) fixed to the hammer drill (2).

14. Tap hole drilling machine according to claim 12 or 13, characterised in that the inward swinging movement of the carrier arm (33) into the supporting position is assisted by its own weight and/or a spring.

15. Tap hole drilling machine according to any one of claims 1 to 6 and 8, characterised in that a pressure medium cylinder controlled by the movement or position of the hammer drill (2) is provided for carrying out the swinging movements of the carrier arm (9, 22, 33).

16. Tap hole drilling machine according to any one of claims 1 to 6 and 8, characterised in that an electric adjusting drive is provided for carrying out the swinging movements of the carrier arm (9, 22, 33).