Abstract:
A device for rotating a work element is disclosed. The device has a support structure, an arm mounted in the support structure in such a way that it can rotate, a rotation drive for rotating the arm around a rotation pin, the rotation drive being located between the arm and the support structure, and a lifting drive. The support structure represents the frame and the arm represents a driven member of a gear. The lifting drive closes the gear between the support structure and the arm. A coupling device is connected in series with the lifting drive in such a way that the lifting drive can be uncoupled from the gear. The coupling device may have a rotating arm and a locking device, for example. The device can be used as a compact rotating device for carrying a blast furnace gun.

Description:
FIELD OF THE INVENTION 
     The invention relates to a swivelling device with jib for swivelling a working unit between a rest position and an operating position. A device of this type is used, for example, to swivel a taphole gun mounted on the jib into an operating position in front of the taphole of a blast furnace and for subsequent pressing of the gun against the taphole. 
     BACKGROUND OF THE INVENTION 
     A conventional swivelling device for a taphole gun comprises in an already known way a jib, the taphole gun being mounted on its free end. The other end of the jib is pivoted in a fixed supporting structure. The swivelling range of the jib should be as large as possible to enable the gun to swivel as far as possible from the runner. Furthermore, it should be stated that modern taphole guns operate with increasingly higher plugging pressures. Consequently the swivelling device, which is to press the plugging gun against the taphole, must also be designed for increasingly higher contact forces. 
     Hydraulic cylinders are currently used in the taphole plugging machines to swivel the jib. When work was still carried out with lower plugging pressures on the blast furnace, rotary motors were also used as the jib drive instead of the hydraulic cylinders. A taphole plugging machine with an electric motor is described, for example, in DE-A-895604. This electric motor transmits its force moment via a toothed-wheel and worm mechanism to the jib. A magnetic brake permits locking of the jib in the operating position. It is obvious that in the case of modern plugging machines with extremely high contact pressures such a solution is no longer economically viable. 
     A taphole gun with a hydraulic cylinder and hydraulic rotary motor is already known from U.S. Pat. No. 3,765,663. An arm securely connected to the jib, on which the piston rod of a double-acting hydraulic cylinder is secured by a first swivel joint, extends radially to the swivelling axis of the jib. The casing of this hydraulic cylinder is secured by a second swivel joint to a fixed arm, which projects a long way beyond the supporting structure of the jib. The hydraulic rotary motor is secured in the jib. It engages via a pinion with a gear wheel securely mounted on the supporting structure of the jib. This rotary motor swivels the jib between a rest and an operating position. The task of the hydraulic cylinder is merely to transmit a force moment to the jib in the operating position in order to press the gun against the taphole and subsequently pull it off again. The hydraulic cylinder is switched on only in a short swivelling range near the furnace. Its two pressure chambers are discharged to the tank over the remaining swivelling range. The stroke of the hydraulic cylinder is designed in such a way that during swivelling of the jib the length of the hydraulic cylinder is automatically adapted to the variable distance between the first and second swivel joints. In other words the swivelling device is a closed three-element mechanism, whereby the supporting structure forms the frame, the supporting arm the driven element, and the hydraulic cylinder, as an element with a variable length, closes the mechanism between the supporting structure and the jib. 
     A swivelling device for a taphole gun, which is intended to be characterised by its compactness, is already known from U.S. Pat. No. 4,247,088. It comprises a jib to carry the taphole gun, a supporting structure, in which the jib is pivoted at one end about a swivelling axis, a rotary drive to swivel the jib between its rest position and operating position and a hydraulic cylinder to generate a contact force. The hydraulic cylinder is supported by a lateral arm of the supporting structure. It is not securely connected to the jib, but can engage in a tooth system when the jib is swivelled into the operating position. 
     SUMMARY OF THE INVENTION 
     The present invention is based on the task of creating a more compact swivelling device. 
     Like the swivelling device from U.S. Pat. No. 4,247,088, a swivelling device according to the invention comprises a jib to carry the working unit; a supporting structure, in which the jib is pivoted at one end about a swivelling axis; a rotary drive to swivel the jib between its rest position and its operating position and a stroke generating drive to produce a contact force. In this configuration, as already mentioned, the supporting structure forms the frame, the supporting arm the driven element of a mechanism, which is closed by a stroke generating drive between the supporting structure and the jib. The swivelling device according to the invention likewise comprises a coupling device, which is connected in series to the stroke generating drive in such a way that the stroke generating drive can be disconnected from the positive movement of the mechanism. In other words an automatic change in length of the stroke generating drive during swivelling of the jib can be prevented by the coupling device. Consequently the total stroke of the stroke generating drive need be designed only for its actual function, i.e. the generation of a contact force in the operating position. By disconnecting the stroke generating drive during swivelling of the jib additional freedom of design with regard to arrangement of the stroke generating drive in the swivelling device is obtained. According to the invention this freedom of design is utilised in that the hydraulic cylinder is arranged along the jib, is supported by the latter and can bear on the supporting structure via the engaged coupling device to transmit a contact force. Consequently the swivelling device according to the invention is extremely compact. Furthermore, the power requirement of the swivelling device can be clearly reduced in many cases by disconnection of the stroke generating cylinder. 
     In a first advantageous embodiment the coupling device comprises a swivelling arm, which is pivoted in the supporting structure. The stroke generating drive is mounted between the swivelling arm and the jib. With the coupling device disconnected this swivelling arm can swivel freely in relation to the supporting structure and the jib, its swivelling axis being essentially coaxial with the swivelling axis of the jib. A locking device permits locking of the swivelling arm in the operating position in relation to the supporting structure, with the result that the stroke generating drive is engaged in the swivelling mechanism to transmit a contact force. 
     In a first embodiment a locking device for the swivelling arm described above has a bolt which can be inserted into and withdrawn from a suitable oblong hole for locking the swivelling arm in relation to the supporting structure. The locking bolt can be inserted in and withdrawn from the oblong hole e.g. by a short-stroke cylinder. 
     In a second embodiment a locking device for the swivelling arm described above has a swivelling locking bar, which in order to lock the swivelling arm can be swung into a position in which it rests against an abutment when the swivelling arm is in the operating position. The advantage of this locking device is that a shock-absorber, which dampens the coupling of the lifting drive to the swivelling mechanism, can be installed relatively easily in the abutment. 
     Swivelling devices according to the invention are advantageously suitable, for example, to carry a taphole gun, the latter being pivoted at the free end of the jib. In a first embodiment of this taphole plugging machine a rigid control rod is flexibly connected to the taphole gun and the supporting structure. This control rod thus determines the alignment of the taphole gun as a function of the swivelling angle of the jib in an already known way. If the swivelling device is equipped with the swivelling arm described above, however, the control rod can also be pivoted on this swivelling arm instead of on the supporting structure. In this case an active adjusting element, which allows the length of the control rod to be varied selectively, is mounted in the control rod so that the alignment of the taphole gun can be determined independently of the jib position. 
     In an alternative embodiment the coupling device comprises a first coupling head at the end of the piston rod of the hydraulic cylinder and a second coupling head on the supporting structure. The two coupling heads are complementary to each other. When the jib is in the operating position the first and second coupling heads are arranged in relation to each other in such a way that the first coupling head can be supported by the second coupling head by extending the piston rod of the hydraulic cylinder. If the jib is swivelled from its operating position towards its rest position, the first coupling head is separated from the second coupling head and the hydraulic cylinder can now be swivelled freely with the jib. The jib advantageously has a spring-centered aligning device for the hydraulic cylinder pivoted on the jib. This aligning device ensures that the hydraulic cylinder always comes to rest in a favorable coupling position when the jib is swivelled into its operating position. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     Exemplified embodiments of the invention are described in more detail on the basis of the enclosed drawings. 
     FIG. 1 shows a plan view of a taphole gun with a swivelling device according to the invention in the rest position in front of the blast furnace; 
     FIG. 2 a plan view of the taphole gun in FIG. 1 in the operating position in front of the blast furnace; 
     FIG. 3 a section along the section line  3 — 3  in FIG. 1; 
     FIG. 4 a section along the section line  4 — 4  in FIG. 3; 
     FIG. 5 a section as shown in FIG. 3 with an alternative locking device, the latter being shown in the unlocked position; 
     FIG. 6 the same section as in FIG. 5, the swivelling device being shown in the locked position; 
     FIG. 7 a plan view as in FIG. 1 with an alternative design of the swivelling device; 
     FIG. 8 a plan view as in FIG. 2 with the swivelling device according to FIG. 7; 
     FIG. 9 a section along the broken section line  9 — 9  in FIG.  8 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a taphole plugging machine  10  according to the invention in a rest position in front of a blast furnace  12 , which is indicated schematically by an arc of a circle. This taphole plugging machine  10  consists essentially of a swivelling device  14  according to the invention and an already known taphole gun  16 . The latter will not be described in more detail. 
     The swivelling device  14  comprises a column-type base  18 , which forms a supporting structure for a jib  20 . Instead of being installed as a base on the floor, this supporting structure  18  can, of course, also be suspended. The jib  20  is pivoted at one end in this supporting structure  18 . In FIG. 1 the position of the swivelling axis of jib  20  in the supporting structure  18  is indicated by the reference number  22 . This axis  22  is generally inclined slightly towards the blast furnace in relation to the vertical. The taphole gun  16  is suspended at the free end of the jib  20 . The position of the swivelling axis of the taphole gun  16  in the jib  20  is shown by the reference number  24 . 
     A relatively short, preferably double-acting hydraulic cylinder  28  lies directly along the jib  20 . One end of this hydraulic cylinder  28 , i.e. the cylinder base in the embodiment shown, is connected by a first swivel joint  32  to the front end of the jib  20 . For this purpose the jib  20  advantageously has a lateral projection, on which the first swivel joint  32  is mounted. The other end of the hydraulic cylinder  28 , i.e. the piston rod end in the embodiment shown, is connected via a second swivel joint  36  to a swivelling arm  38 . The latter is pivoted in the supporting structure  18 , so that its swivelling axis is essentially coaxial with the swivelling axis of the jib  20 . 
     The mounting of the jib  20  and swivelling arm  38  in the supporting structure is shown in more detail in FIG.  3 . The jib  20  has at its supported end a cylindrical connection piece  40 , which is secured by means of a ball bearing  42  to a flange  44  of the supporting structure  18 . The outer raceway  46  of this ball bearing  42 , i.e. the raceway on which the connection piece  40  is secured, forms a gear rim  48 . A rotary motor, which may be designed, for example, as a hydraulic motor or electric motor, is designated  50 . This rotary motor  50  is secured to the flange  44  and can engage in the gear rim  48  by means of a pinion  52 . Consequently the rotary motor  50  can swivel the pivoted jib  20  about the axis  22 . The exact angular position of the jib  20  is measured by an angle sensor  51  during swivelling. The latter is secured to the flange  44  like the rotary motor  50  and can engage in the gear rim  48  by means of a pinion  53 . 
     The swivelling arm  38  is pivoted at the top end of the column-type supporting structure  18  by means of a ball bearing  54 . As shown in FIG. 3, the inner raceway  56  of the ball bearing  54  is secured to a second flange  58  on the supporting structure  58  and the outer raceway  60  on the swivelling arm  38 . The ball bearing  54  is coaxial with the ball bearing  42 , so that the swivelling axis  22  of the jib  20  is identical with the swivelling axis of the swivelling arm  38 . 
     A locking device is designated  62  in FIG.  3 . This locking device  62  permits locking of the swivelling arm  38  on the supporting structure  18  to prevent rotation. For this purpose it comprises a locking bolt  64 , which can be inserted in and withdrawn from an oblong hole  66  in a front cover plate  68  of the supporting structure  18  (see also FIG.  4 ). In a preferred embodiment the locking bolt  64  is formed by a piston of a short-stroke cylinder  70  secured on the swivelling arm  38 . 
     Schematically represented flexible hydraulic connection lines of the hydraulic cylinder  28  are designated  72 ,  74  in FIG.  3 . These hydraulic connection lines  72 ,  74  are advantageously incorporated in a hydraulic circuit  78  via a rotary connection  76 . The lower part of the rotary connection is secured with prevention of rotation on the supporting structure  18 , whereas the upper part, to which the lines  72 ,  74  are connected, is freely rotatable. 
     To summarise, it should be stated that the swivelling device  14  with the locked swivelling arm  38  is—from the kinematic point of view—really a closed three-element swivelling mechanism, whereby the supporting structure  18  forms the frame, the jib  20  the driven element and the hydraulic cylinder  28  as a sliding element closes the mechanism between the supporting structure and the jib. In this closed three-element swivelling mechanism the length of the sliding element, i.e. the hydraulic cylinder  28 , would have to adapt to the position of the jib  20 . In other words the stroke of the hydraulic cylinder  28  would have to vary continuously during swivelling of the jib  20  by the rotary motor  50 . When the swivelling arm  38  is unlocked, however, the hydraulic cylinder  28  is disconnected from the swivelling mechanism, i.e. the swivelling device is—from the kinematic point of view—now an open mechanism with the rotary motor  50  as the sole drive or, in other words, a change in the position of the jib no longer causes a change in the stroke of the hydraulic cylinder  28 . The swivelling arm  38  and locking device  62  thus form a coupling device, which is connected in series to the hydraulic cylinder  28  and with the aid of which the hydraulic cylinder  28  can be disconnected from the swivelling mechanism during swivelling of the jib  20  by the rotary motor  50 . 
     The method of operation of the swivelling device  14  described above will now be described in more detail with reference to FIGS. 1 and 2. In FIG. 1 the jib  20  with the taphole gun  16  is in a rest position. The piston rod of the hydraulic cylinder  28  is fully retracted. The locking device  62  is unlocked, i.e. the hydraulic cylinder  28  is disconnected from the swivelling mechanism. If the rotary motor  50  is actuated, the jib  20  is swivelled from the rest position in FIG. 1 into the operating position in FIG.  2 . The freely rotatable swivelling arm  38 , which is connected via the hydraulic cylinder  28  to the jib  20 , is swivelled with the jib  20  in the direction of the arrow  80 . During swivelling of the jib into its operating position the locking bolt  64  lies above the oblong hole  66  in the supporting structure  18  at a specific angular position of the jib  20 . In this position the short-stroke cylinder  70  can be actuated, whereby the locking bolt  64 , which had until now been retracted, enters the oblong hole  66  of the supporting structure  18  and assumes the position shown in FIG.  3 . The extension of the locking bolt  64  is advantageously tripped via the angle sensor  51  as a function of the angular position of the jib  20 . As soon as the locking bolt  64  is inserted into the oblong hole  66 , the piston rod of the hydraulic cylinder  28  can be extended. Consequently the swivelling arm  38  is swivelled in the opposite direction of the arrow  80  until the locking bolt  64  rests against a first closure  82  of the oblong hole  66  in the supporting structure  18 . When the locking bolt  64  is in this position, the hydraulic cylinder  28  is incorporated in the swivelling mechanism for transmission of a pressing force to the jib  20 . In other words the hydraulic cylinder  28  bears via the swivelling arm  38  and the locking bolt  64  on the supporting structure  18  in order to exert a force moment on the jib  20 , with the result that the taphole gun is pressed against the taphole. For subsequent pulling of the gun from the taphole the piston rod of the hydraulic cylinder  28  is retracted. In this case the locking bolt  64  first moves in the oblong hole  66  until it rests on a second closure  84  of the oblong hole  66  in the supporting structure  18 . When the locking bolt  64  is in this position, the hydraulic cylinder  28  is incorporated in the swivelling mechanism for transmission of a force moment acting in the opposite direction to the jib  20 . In other words it bears via the swivelling arm  38  and the locking bolt  64  on the supporting structure  18  in order to swivel the jib  20  away from the blast furnace  12 . While the hydraulic cylinder  28  is actuated for pressing on or pulling away the taphole gun  16 , the rotary motor  50  advantageously idles. During subsequent swivelling of the jib from its operating position the locking bolt  64  is withdrawn from the oblong hole  66  at a specific angular position of the swivelling arm  38 . The rotary motor  50  can now swivel the jib  20  back into the rest position shown in FIG. 1 without the need for the hydraulic cylinder  28  to change its length. 
     The taphole gun  16  is advantageously aligned at the taphole via a control rod. A conventional control rod, which is pivoted at one end on a fixed point of the supporting structure  18  and at the other end on the taphole gun  16  (see, for example, FIGS.  7  and  8 ), could be used in this case. However, a new control rod arrangement is shown in FIGS. 1 and 2. It is a control rod  90  of variable length, which is pivoted at one end on the swivelling arm  38  and at the other end on the taphole gun  16 . The length of the control rod  90  is varied via a built-in stroke generating drive, for example a hydraulic cylinder  92  or a spindle drive. During swivelling of the jib  20  from the rest position into the operating position the length of the control rod  90  is changed synchronously by admission of pressure to the hydraulic cylinder  92 . The control rod  90  rests on the swivelling arm  38  locked by the hydraulic cylinder  28  in order to swivel the taphole gun  16  about the swivelling axis  24 . This control rod arrangement has important advantages. Firstly, it should be noted that the control rod  90  is always on the same side of the jib  20 . In other words the control rod  96  must not cross the jib  20  during swivelling. Consequently the overall height of the machine is reduced. Secondly, it should be noted that alignment of the taphole gun during swivelling can be designed substantially more flexibly than with a conventional control rod. A comparison of FIGS. 1 and 7, for example, reveals that the machine in FIG. 1 has a substantially more compact position than the machine in FIG.  7 . It should also be emphasized that in this embodiment the jib  20  can perform a complete revolution about its swivelling axis  22 . 
     An alternative embodiment of the locking device of the swivelling arm  38  will be briefly explained with reference to FIGS. 5 and 6. This locking device comprises a swivelling locking bar  96  on the supporting structure  18  and at least one abutment  98  on the swivelling arm  38 . In FIG. 5 the swivelling locking bar  96  is shown in the unlocked position of the locking device. In FIG. 5 the swivelling locking bar  96  is shown resting against the abutment  98 . A shock-absorber, which dampens the engagement of the hydraulic cylinder  28  in the swivelling mechanism, can be integrated very easily in the abutment  98 . It should be noted that the swivelling device advantageously has two abutments arranged at an angle to each other, the swivelling locking bar resting against the first abutment when the taphole gun  16  is pressed against the taphole and against the second abutment when the taphole gun  16  is pulled away from the taphole. 
     An alternative embodiment of the entire coupling device of the hydraulic cylinder  28  is described with the aid of FIGS. 7 and 8. This coupling device comprises a first coupling head  110  at the end of the piston rod  130  of the hydraulic cylinder  128  as well as a second coupling head  112  on the supporting structure  18 . The second coupling head  112 , which is complementary to the first coupling head  110 , is designed as a fixed point on the supporting structure  18 . When the mounting is in the operating position (see FIG. 8) the first and second coupling heads  110 ,  122  are arranged in relation to each other in such a way that the first coupling head  110  can bear on the second coupling head  112  when the piston rod  130  of the hydraulic cylinder  128  is extended. In this position the hydraulic cylinder  128  is engaged in the swivelling mechanism for transmission of a contact force to the jib  20 . 
     The hydraulic cylinder  128  is pivoted on a projection  132  of the jib  20 . A lever  134  connects its swivelling axis to a spring-centered aligning device  136  on the jib  20 . This aligning device  136  aligns the disconnected hydraulic cylinder  128  essentially parallel with the jib  20  and thus facilitates disconnection of the two coupling heads  110  and  112  when the jib  20  is in the operating position. 
     In FIG. 9 the two coupling heads  110  and  112  are shown in the coupled position. It can be seen that the first coupling head  110  has two journals  140 ′,  140 ″, which are arranged symmetrically with the axis  144  of the hydraulic cylinder  128 . In the coupled position these journals  140 ′,  140 ″ are mounted in corresponding bearing recesses  142 ′,  142 Δ (see FIG. 7) of the second coupling head  112 . The reference number  146  indicates a hole in the first coupling head  110 , through which a locking bolt  148  can be inserted. With the aid of this locking bolt  148  the first coupling head  110  can be mechanically locked in the supporting structure, so that the hydraulic cylinder  128  can also be used to pull the taphole gun  16  from the taphole. The locking bolt  148  can be actuated, for example, by a small hydraulic cylinder  150 , which is secured to the supporting structure  18 . Alternatively, however, the rotary motor  50  can also be designed for pulling the taphole gun  16  from the taphole. The force moment required for this purpose is in fact substantially smaller than the force moment required for pressing the taphole gun  16  against the taphole. 
     Finally, it should be noted that the swivelling devices described are particularly advantageous if a large swivelling angle and a high contact force are required. Further advantages are their compactness and low oil consumption. For this purpose it should be noted that a low oil consumption not only has a favorable effect on the design of the hydraulic system, but in most cases likewise has a positive effect on the energy consumption of the swivelling device.