Patent Publication Number: US-8109168-B2

Title: Converter gearing having eccentric bushes

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns converter gearing, which comprises a gear rim, which is connected to the axis of rotation of a converter vessel and engages at least one drive pinion of the converter gearing, and at least one locking device, which can be swung in or out to engage with or disengage from the teeth of the gear rim and has the form of a locking arm, which is mounted on a horizontal shaft and is configured with teeth, wherein the shaft is supported in a terminal bearing, the locking arm can be nonpositively engaged with or disengaged from the teeth by active force elements, e.g., hydraulic cylinders, and the shaft is supported in the housing of the converter gearing by two eccentric bushes, which rotate freely, one within the other, at each end of the shaft, in such a way that an ideal engagement position of the interacting toothed regions of the locking device and the gear rim can be set by independent rotation of the eccentric bushes, and a clamping element for adjusting a low-backlash bearing is associated with each of the eccentric bushes and the bores which hold the eccentric bushes. 
     Converter gears are subjected to high and variable torques during the oxygen-blowing operation. These torques usually lead to extreme loads per unit surface area and thus to excessive wear of the teeth. 
     It is well known that the harmful loads can be significantly reduced by the use of a locking arm. The terminal toothing of the locking arm for locking engagement in the teeth of the gear rim on the converter vessel corresponds as a “negative form” to about 5 to 6 tooth spaces of the driven gear. The load thereby evenly distributed to a region of the toothing results in a significant reduction of the surface pressure on the toothing and thus a reduction of the wear caused by the surface pressure. 
     A disadvantage of this design is the required setting precision of the locking lever and its bearing, especially when two independent locking levers are installed. This means that even small deviations from the ideal engagement position can lead to extremely high forces and stresses and thus to faster wear of the gear rim and the locking arm teeth. 
     To avoid these consequences, use was made of the measure of machining the housing and locking arm bore together. To do this, it is necessary to preassemble the gear rim and locking arm in their optimum position in the housing, then to fasten them in place and, finally, to machine them together. 
     This not only results in high production costs, but also has the further disadvantage that subsequent replacement or readjustment of the locking arm is not possible due to the special machining sequence. 
     The document EP 1 022 482 A1 describes a device for locking an element of a kinematic chain on a casting ladle, which comprises a part with an area of relief-like elevations and depressions provided on its periphery, which are complementary to areas with relief-like depressions and elevations on the element to be locked, and a device, which is installed at the end of a locking arm, for moving the part between a passive position “disengaged” from the element to be locked and an active position, in which the elevated and depressed areas of the element and the part penetrate each other to lock the element in a predetermined position. Indicating devices for the element in the predetermined position with respect to its elevated and depressed areas and devices for indicating the position of the locking arm are also provided. 
     The document GB 809 683 A concerns an improvement of the adjustable bearings of bolts, shafts, and similar elements. It describes the possibility of being able to adjust the position of these elements in all radial directions. Eccentric bushes that can be rotated one within the other are used for this purpose. The inner bush holds the shaft, while the outer bush is mounted in the housing. This produces the required possibilities for adjusting the shaft in all radial directions. 
     To maintain an adjusted position in a locking device, the document GB 590 202 A proposes that the eccentrics be locked on conical, rotationally symmetric plates by an outer screw connection with a set bolt. It is readily apparent that this is an extremely expensive and complex arrangement that requires a considerably greater construction space. 
     SUMMARY OF THE INVENTION 
     Proceeding from the prior art described above, the objective of the invention is to produce converter gearing of the type specified in the introductory clause of claim  1  with an improved design and to design it in such a way that the optimum setting precision of the locking lever relative to the gear rim of the gearing can be readjusted at any time independently of the production of these elements. 
     In accordance with the invention, to achieve this objective in converter gearing of the type described above, it is proposed that the clamping element is a clamping bush that can be expanded in its inside and outside diameter by means of axial keys. 
     The design of the support of the locking arm in accordance with the invention results in the great advantage that optimum adjustability of the backlash of the drive toothing of the gearing can be achieved at any time and independently of its production, and/or the backlash can be readjusted. This results in an even load distribution in the region of the locking teeth with about 5 to 6 tooth spaces of the region of engagement of the driven gear with drastically reduced load per unit surface area of the tooth flanks. The wear of the gear wheels of the gearing is reduced accordingly. 
     A method of adjusting a low-backlash bearing of the shaft of the locking arm of a design in accordance with the invention is distinguished by the fact that an optimum engagement of the toothed region of the locking device is first set by rotation of the eccentric bushes of the shaft with the clamping elements released, and that the clamping elements of the two terminal bearings are then brought into a low-backlash bearing state by expansion, and the eccentric bushes are locked in the setting they have then reached. 
     Further details, features, and advantages of the invention are revealed by the following explanation of several embodiments, which are shown schematically in the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  shows converter gearing in a side view. 
         FIG. 2  shows the mounting of the shaft of a locking arm in eccentric bushes in the sectional plane indicated by I-I in  FIG. 1 . 
         FIG. 3  shows an axial cross section of a pair of eccentric bushes mounted one inside the other in an eccentric position. 
         FIG. 4  shows various eccentric positions of eccentric bushes mounted one inside the other. 
         FIG. 5  shows another eccentric position of eccentric bushes mounted one inside the other. 
         FIG. 6  shows another eccentric position of eccentric bushes mounted one inside the other. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a side view of converter gearing, which comprises a gear rim  7 , which is connected to the axis of rotation  6  of a converter vessel (not shown) and engages at least one drive pinion  8  of the converter gearing  9 , and at least one locking device, which can be swung in or out to engage with or disengage from the teeth of the gear rim  7  and has the form of a locking arm  12 , which is mounted on a horizontal shaft  10 , is configured with teeth  11  in its end region, and is rotatably supported. 
     The locking arm  12  is supported with the shaft  10  in at least one terminal bearing  13 ,  13 ′ and can be nonpositively engaged with the teeth of the gear rim  7  or disengaged from the teeth of the gear rim  7  by means of active force elements  14 ,  14 ′, e.g., hydraulic cylinders, which preferably act on its end regions. The shaft  10  of the locking arm  12  is supported in the housing of the converter gearing  9  by two eccentric bushes  4 ,  5 , which rotate freely, one within the other, at each end of the shaft  10 . An ideal mutual engagement position of the two interacting toothed regions of the locking device  12  and the gear rim  7  can be set by independent rotation of the eccentric bushes  4 ,  5 . 
     A clamping element  16 ,  16 ′ for adjusting a low-backlash bearing  13 ,  13 ′ is associated with each of the eccentric bushes  4 ,  5  and the bores  18 ,  18 ′ of the converter gearing  9  which hold the eccentric bushes. This can be accomplished if, for example, the clamping element  16  is a clamping bush  19  that can be expanded in its inside and outside diameter by means of axial keys  17 . 
     The adjustment of a backlash-free bearing  13 ,  13 ′ of the shaft  10  of a locking arm  12  of the locking device and the adjustment of optimum engagement of the toothed region of the locking arm  12  with the gear rim  7  of the converter gearing  9  are accomplished by rotation of the eccentric bushes  4 ,  5  with the clamping elements  16  released. The clamping elements  16  of the two terminal bearings  13 ,  13 ′ are then brought into a low-backlash bearing state by expansion, and the eccentric bushes  4 ,  5  are locked in their setting. 
       FIGS. 3 to 6  show different states of the penetration of the outer eccentric bushes  5  by the inner eccentric bushes  4 . 
     In these drawings, the centers of rotation of the outer bushes  5  are labeled with the reference number “ 1 ”, the centers of rotation of the inner bushes  4  are labeled with the reference number “ 2 ”, and the centers of the bores in the inner bushes  4  are labeled with the reference number “ 3 ”. 
       FIG. 3  shows the so-called zero position, in which the eccentricities of the two bushes offset each other. The eccentricity of a bush is thus characterized by the indicated distance “S”. 
     LIST OF REFERENCE NUMBERS 
     
         
           1  center of outer bush 
           2  center of inner bush 
           3  center of a bore of the inner bush 
           4  inner eccentric bush 
           5  outer eccentric bush 
           6  axis of rotation of the converter vessel 
           7  gear rim 
           8  drive pinion 
           9  converter gearing 
           10  horizontal shaft 
           11  toothing 
           12  locking arm 
           13  bearing 
           14  active force element 
           16  clamping element 
           17  axial keys 
           18  bore