Press apparatus for reducing widths of hot slabs and slab widths reducing method using the apparatus

Abstract: A press apparatus for reducing widths of hot slabs (7) comprises a pair of anvils (8) movable toward and away from each other in width directions of the hot slabs (7), width reduction heads (6) to which the pair of anvils (8) are attached, respectively, and eccentric presses (2, 3) for reciprocatively driving the width reduction heads (6) through sliders (4), respectively. The apparatus further comprises width adjusting means (5,11,12,13) incorporated in the eccentric presses (2,3), respectively, for changing distances between the width reduction heads (6) and the sliders (4). Each of the anvils (8) has a parallel portion in parallel to a feeding direction of the hot slabs (7) and an inclined portion on an entry side in the feeding direction. With this arrangement, the reducing distance can be set according to the desired distance of reduction in width in continuous width reduction and the reduction in width can be continuously effected with the set reducing distance with high efficiency. The press apparatus preferably further comprises buckling preventing means such as rollers controlled by hydraulic cylinders for urging at least two locations of the slab (7) along a central longitudinal line of the slab (7) and on upstream and downstream sides of a line connecting junctions of the parallel portions and the inclined portions of the anvils (8), thereby preventing any buckling of the slab (7) occurring in reduction in width of the slab (7).

Description: This invention relates to a press apparatus for reducing widths of hot slabs by repeatedly pressing hot slabs in their width directions whilst feeding the slabs relatively to anvils, and a method of reducing the widths of the hot slabs by the use of the press apparatus. It is very advantageous to change or reduce widths of slabs produced by continuous casting according to widths of plate products to be produced from the slabs before rolling in roughing mills. In this case, presses are effectively applied for the reduction in width, particularly, when widths to be reduced are large. In reducing widths of slabs, it has been mainly used to combine "V-rolling" using vertical rolls and "H-rolling" using horizontal rolls. In order to prevent irregular shapes such as "fishtails" or "tongues" produced at preceding and trailing ends of slabs, a feature of preforming-pressing the preceding or trailing ends of slabs to prevent the irregular shapes has been disclosed in Japanese Laid-open Patent Application No. 58-53,301, wherein press apparatuses and vertical and horizontal rolling mills are provided to effect reversing rolling using vertical and horizontal rolls after pressing by the press apparatuses. In order to carry out the width reducing method in existing hot rolling factories, strong vertical type reverse rolling mills, horizontal type reverse rolling mills and preforming presses for pressing preceding and trailing ends of slabs are needed. In fact, it is very difficult to obtain a wide space for locating these bulky apparatuses, and they increase initial cost of the installation. In EP 0 112 516 there is disclosed according to the preamble of claims 1 and 3, a press type method of reducing the slab width wherein a slab as a rolling stock is reduced in width before rolling, which method comprises: employing as press tools a pair of opposing members at least one of which has an inclined press surface adapted to vibrate in the slab width direction; and moving the slab substantially continuously while continuing the vibration of the press tool. Also disclosed is an apparatus suitably employed for the above method. By the method and apparatus, the clearance between the press tools is reduced to make it possible to shorten the operating time as a whole. In addition, the pressed surfaces of the slab are made smoothly continuous thereby to permit improvements also in formability and production yield. In Japanese Laid-open Patent Application No. 59-101201, on the other hand, a continuous width reducing method with a press for slabs has been disclosed which is able to save space and to decrease the initial cost of the installation. In this method, however, distances to be reduced in width of slabs should be set according to required reduced widths of slabs when initial widths of the slabs or widths of plate products are within various ranges. Such a setting of widths may detrimentally affect the efficiency in working of continuous width reduction. In width reduction by vertical and horizontal roll rolling mills hitherto used, there is a possibility of buckling by rolling with the vertical rolling mills. Accordingly, the maximum value Δw of width reduction is usually set to be ΔW<½T 0 , where T 0 is the initial thickness of the slab, so that the width reduction is effected within a range less than the limit value for preventing the buckling. With a sizing mill capable of controlling tensile forces between the vertical and horizontal roll rolling mills, tensile force is applied by the horizontal rolling mill on an exit side to a slab being rolled by the vertical rolling mill so as to increase the limit value to make large the reduction in width of the slab. However, this method also remains in the fact that the reduction in width is limited by the above limit value for preventing the buckling. In contrast herewith, it has been also proposed to positively hold a slab by a set of holding rolls arranged at a center of width of the slab on an axis connecting vertical rolls of an edger in order to avoid the buckling (Japanese Laid-open Patent Application No. 57-168707). Moreover, the feature of providing two sets of holding rolls on both sides of a center of width of the slab is disclosed in the text of the lecture meeting "Iron and steel" published by Japanese Iron and Steel Society, autumn of 1983, 69-5 (1983) S350, 349. These methods make possible the reduction in width of slabs beyond the above limit value. In reducing the width of hot slabs by means of a press using anvils having flat portions in parallel to the proceeding direction of the slabs and inclined portions at their front and rear ends, on the other hand, there are three forms of pressing, i.e., preforming preceding ends, preforming trailing ends and steady pressing, and the resulting deformed zones of the slabs are large. Consequently, buckling is likely to occur when the reduction in width is large. It has been found that only one holding position by holding means between anvils is insufficient. It is an object of the invention to provide a method and apparatus which enable slabs to be reduced in width with a high quality and in which width reduction heads can be moved relatively to anvils to make easy the setting of distances to reduce in width of slabs to provide required widths. In order to provide these objects, there is provided a method according to accompanying claim 1 and a press apparatus according to accompanying claim 3. For a better understanding of the invention and to show how the same may be carried into effect, reference will be made, by way of example, to the accompanying drawings in which:- Fig. 1 is an illustration of patterns of pressing slabs to cause buckling in slabs according to the prior art; Fig. 2 is a schematic view illustrating a press apparatus according to the invention; Fig. 3 is a partial view for explaining a part encircled by a broken line III of the apparatus shown in Fig. 2; Fig. 4 is an explanatory view of the anvil used for the press apparatus according to the invention; Fig. 5 is a sectional view taken along a line V-V in Fig. 2; Figs. 6-10 are illustrations for explaining the reduction in width of hot slabs according to the invention; Fig. 11 is an explanatory view for the pitch of hot slab feeding; Figs. 12a-12c are illustrations showing the relation between a slab and an anvil in reducing in width of the slab according to the invention; Figs. 13a-13d are illustrations for explaining relations between the lapse of time and the operation of the anvil and the slab shown in Figs. 12a-12c; A width reducing press apparatus according to the invention will be explained by referring to Fig. 2 which incorporates eccentric presses therein using crankshafts. In the drawing, the press apparatus comprises a housing 1, crankshafts 2 rotatably extending through the housing 1, and sliders 4 connected through connecting rods 3 to the crankshafts 2 and slidable along inner walls of the housing 1. Each of the sliders 4 is reciprocatively driven through the connecting rod 3 and the crankshaft 2 driven by a motor (not shown). Each of the sliders 4 is formed with four internally threaded apertures 4a in which threaded portions of screw-threaded rods 5 are threadedly engaged. A width reduction head 6 is fixed to one end of each screw-threaded rod 5. An anvil 8 is fixed to the width reduction head 6 for reducing the width of a slab 7. Moreover, each of the screw-threaded rods 5 is formed on the other end with spline grooves 5a on which is engaged a splined gear 9 in mesh with a pinion 10 as shown in Fig. 3. The pinion 10 is rotated through a universal spindle 11 by a reduction gear device 13 connected to a motor 12 to rotate the screw-threaded rod 5 through the splined gear 9. As the screw-threaded rods 5 are rotated, they axially move in the internally threaded apertures 4a of the slider 4 to change a relative position between the slider 4 and the width reduction head 6 fixed to the ends of the screw-threaded rods 5, thereby enabling the position of the anvil 8 to be adjusted. Such an adjustment of the relative position between the slider 4 and the width reduction head 6 is referred to herein as "width adjustment" and its function will be clear in the later explanation. Moreover, each anvil 8 includes a parallel portion 14 in parallel with a proceeding direction of the slab 7, an inclined portion 15 at a rear end or an entry side facing the proceeding slab 7, and an inclined portion 15a on a front end or an exit side. However, the inclined portion 15a on the exit side is not necessarily needed. When preforming the trailing end of the slab 7 is not effected as shown in Fig. 4. Although only members associated with the one anvil 8 have been explained, more members associated with the other anvil 8 are of course provided to form one press apparatus. Moreover, the slab 7 is transferred by pinch rolls 16 and a high speed transferring roller table 17. If required, lower buckling preventing rollers 18 and upper buckling preventing rollers 19 may be provided in the housing 1 in order to prevent the buckling of the slab produced in reducing the width of the slab as shown in Fig. 5. The reduction in width of the slab will be explained by referring to Figs. 6-10. For the sake of convenience of explanation, only the operation of the one anvil 8 will be explained. In fact, however, a pair of the anvils are of course operated. As shown in Fig. 6, the slab 7 is fed between the anvils 8 which have been set whose minimum distance therebetween is wider than a width of the slab 7 and stopped so as to permit a preceding end of the slab to be positioned at a location where an unsteady deformation caused by the preforming is minimum. The crankshaft 2 starts from a lower dead point (LDP in Fig. 6) to an upper dead point (UDP) to widen the distance between the slab 7 and one of the anvils 8. Therefore, during the movement of the crankshaft 2 from the lower dead point to the upper dead point, the screw-threaded rods 5 are rotated so as to move in its axial direction, so that the width reduction head 6 is moved relatively to the slider 4 so as to approach to the slab 7 (Figs. 7 and 8). Furthermore, while the relative position between the slider 4 and the width reduction head 6 as shown in Fig. 8 is kept, the crankshaft 2 moves from the upper dead point to the lower dead point so that the reduction in width of the slab is accomplished (Fig. 9). Moreover, if it is required to effect the reduction in width more than two times the stroke of the crankshaft, the above reduction in width is repeatedly effected many times. Furthermore, the preforming of the trailing end of the slab can be effected in the same manner as that of the preceding end of the slab. Namely, before an irregular shape such as a "tongue" occurs at the trailing end of the slab, the slab is fed onto the exit side and the preforming of the trailing end is effected with an inclined portion 15a of the anvil at its front end or an exit side in the same manner as that of the preceding end. It is also possible to effect the preforming of the trailing end prior to the preforming of the preceding end. After the width reduction of the slab has been effected, the slab is fed at a higher speed as shown in Fig. 10. When the crankshaft 2 is rotated, the anvil 8 is operated with a constant stroke. When the anvil 8 is moved during the movement of the crankshaft 2 from the lower dead point to the upper dead point, the anvil 8 moves away from the slab 7. Accordingly, the slab 7 is fed between the pair of anvils 8 during the movement of the crankshaft 2 to the upper dead point, and the next reduction in width is effected during the movement of the crankshaft 2 from the upper dead point to the lower dead point. The slab is fed in increments of a predetermined distance which is referred to herein "pitch P" indicated in the following formulas, where an inclined angle of the inclined portion 15 of the anvil 8 is , a reduced distance of the slab 7 by one anvil 8 in one reduction is Y, a stroke of the anvil 8 is S t , and a distance of width of the slab to be reduced is Δw. 1) P = Y·tan (90°-) where Δw/2>S t ≧Y 2) P≦ℓ (length of the parallel portion of the anvil) The slab is fed with this pitch and the reduction in width continues. A gap G in Fig. 11 serves to prevent any collision of the slab with the anvils. Referring to Figs. 12a-12c and 13a-13d, the relation between a slab and an anvil will be explained in case of that a rotating radius of crankshafts is 50 mm, the reduced distance in width of slabs by one anvil is 175 mm, and the angle  of inclined portion of the anvil is 12°. In these figures, Y uo is the movement of the anvil caused by the rotation of the crankshaft or the movement of the slider, Y W is the width adjustment amount (in other words, the movement of the width reduction head), and Y u is the substantial or actual movement of the anvil (Y uo +Yw). In this case, Y S indicates the variation in the distance between the side edge of the slab and the reduced position to be aimed by one anvil in a vertical line passing through the point A of the anvil. The gap G is the distance between the slab and the anvil. Fig. 12a illustrates a condition of preforming a preceding end of the slab 7. The anvil 8 is illustrated in an awaiting or posing position 8 o in solid lines and in first and second stage preforming positions 8a and 8b in phantom lines. In this case, as the rotating radius of the crankshaft is 50 mm and its stroke is 100 mm, two stages of reduction with reduced distances 85 mm and Y sb =90 mm are required in order to achieve the reduced distance of ΔW/2=175 mm. The Y sa is 85 mm+90 mm=175 mm and the Y sb is 90 mm. Fig. 12b illustrates a condition of the steady reduction. The positions 8 o and 8 c of the anvil correspond to the positions of the crankshaft at the upper dead point and lower dead point, respectively. The slab 7 is fed at a high speed from the position where the preceding reduction has been completed corresponding to the position 8c shown in Fig. 12a to the position shown in solid lines in a direction shown by an arrow F to effect a next reduction in width of the slab. In this case, the fed distance of the slab or the pitch is approximately 400 mm calculated from 85(mm)×tan(90°-12°)≃400 mm , where the gap is 15 mm and the reduced distance is Y s =85 mm. Fig. 12c illustrates the preforming of a trailing end of the slab 7. For example, when the reduction in width of the slab has proceeded to a predetermined position in the proximity of the trailing end (corresponding to the position 8d of the anvil 8), the pair of anvils 8 are once opened to the positions 8 o where the anvils 8 do not interfere with the slab 7 and the slab 7 is advanced by a distance L in the direction F. The slab 7 is stopped when the trailing end 7' arrives at a starting point B of the inclined portion of the anvil at its front end or the exit end, and the first and second stage preformings at the trailing end are effected. Figs. 13a-13d illustrate the operation of one anvil corresponding to lapse of time during the preforming the preceding end, the steady reduction in width and the preforming the trailing end of the slab. In these drawings, abscissas indicate the lapse of time (t=0 is the starting point) and ordinates show positions Y of the anvil in the width direction (Y=0 corresponds to the edge of the slab completely reduced in width or a location of 175 mm from an initial edge of the slab which has not been reduced in width). A letter S is a point from which the anvil starts, and a letter P is a point from which the reduction in width of the slab starts by the anvil. A letter Z is a point at which the width adjustment has been completed. In Fig. 13a, the anvil stands or waits at a point S a of 190 mm with a gap of 15 mm for the first stage preforming. The crankshaft starts to rotate from the lower dead point toward the upper dead point, so that this movement of the crankshaft causes the anvil moves along a curve Y uo . On the other hand, the width adjustment is effected along a curve Y w slightly behind the movement of the anvil along the curve Y uo and is stopped at a point Z a after the width adjustment of 100 mm. Therefore, the actual movement of the anvil is shown by a curve Y u . The first stage preforming is completed at a point S b . In this case, after the crankshaft has been returned from the lower dead point to the upper dead point, the reduction in width of the slab is started. The reason is that if the reduction is started when the crankshaft is still at a position near to the upper dead point, the torque produced from the motor is insufficient to carry out the reduction so that the reduction in width may become impossible. Fig. 13b illustrates the second stage preforming at the preceding end of the slab continuously following the above first stage preforming. In this case, an amount of the width adjustment is 90 mm because the total reduced distance by the anvil in the first and second stage preformings is 175 mm and the width adjustment of 85 mm in the first stage has been completed. Fig. 13c illustrates continuous steady width reduction. In this case, the width adjustment is not needed as shown in Fig. 12B and the anvil moves along a line Y u =Y uo by the rotation of the crankshaft. On the other hand, the slab starts to move slightly behind the crankshaft passing through the lower dead point S and stops short of the reduction starting point P. This stopped position of the slab is set so that the gap G is 15 mm and Y s is 85 mm at the location corresponding to the point A of the anvil (Fig. 12b) from which the inclined portion 15 of the anvil on the rear or entry side starts. In Fig. 13c, as the side edge of the slab corresponding to the point A of the anvil is the position where the width reduction has been completed, Y s is zero at its initial time. As the slab is advancing Y s increases. When Y s arrives at 85 mm (the distance to be reduced), the slab is stopped. The reduction in width is started from the point P where the lines Y s and Y u intersect. The reduction continues to the point where Y=0. Fig. 13d illustrates the preforming the trailing end of the slab. After the steady reduction has been completed, the crankshaft continues its rotation to the upper dead point, during which the anvil moves along a curve Y uo . On the other hand, the width adjustment starts slightly behind the point S in the direction opening the pair of anvils to a value of 190 mm and then is once stopped as shown in a curve Y w1 . Thereafter, as shown in a curve Y w2 the width adjustment again starts in the direction closing the anvils to a value of 100 mm and thereafter the width adjustment is stopped at a point Z where the preforming of 85 mm at the trailing end is possible in the first stage preforming. During the width adjustment, the slab is moved and is stopped when the trailing end 7' of the slab arrives at a point B of the anvil. On the other hand, Y s increases progressively and passes through a point of 175 mm which has not been reduced, and the trailing end 7' intersects the line Y s . Moreover, Y s ' indicates the distance in width to be reduced by one anvil in the vertical direction passing through the point B of the anvil. Moreover, the actual movement of the anvil corresponds to a line Y u so that the gap of 15 mm can be maintained even when the anvil and the slab approach each other to the minimum possible distance. The reduction in width starts from the point P where the curves Y u and Y s ' intersects. Thereafter, the second stage preforming at the trailing end of the slab is effected in the same manner as shown in Fig. 13b. Moreover, in the case where preforming of the trailing end is effected prior to preforming of the preceding end, it can be carried out by the use of the inclined portions 15a of the anvils on the exit side in the same manner as in the preceding end, although the case is not shown in the drawings. As can be seen from Figs. 13a-13d, there is no interference between the side edge of the slab and the movement of the anvil shown in the line Y u , prior to the point P where the reduction starts. As shown in Figs. 13a and 13d, particularly, it is clear that the adjustment of reduction position of the anvil can be easily and simply effected during the rotation of the crankshaft. According to the invention, the reducing distance can be set according to the desired distance of reduction in width in continuous width reduction including the preforming of a slab, and the reduction in width of slabs can be continuously effected with the set reducing distance with high efficiency. The buckling is likely to occur when the reduction in width of the slab is effected as we mentioned in the preamble in the specification. The inventors of the invention have investigated the occurrence of the buckling to find that such a buckling throughout a slab from its preceding end to its trailing end can be prevented by holding the slab at more than two locations along a rolling direction or a longitudinal direction of the slab by means of, for example, rollers.

Claims: A method of reducing the width of a hot slab (7) by using width reduction heads (6) to which are attached a pair of anvils (8) movable towards and away from each other in width directions of the hot slab (7) and by feeding the slab (7) between the pair of anvils (8) disposed respectively adjacent to the edges of the slab (7), each anvil (8) having a parallel portion (14) which is substantially parallel to the feed direction of the hot slab and an inclined portion (15) at the entry side of the feed direction and being associated with means for adjusting the position of the anvil (8) with respect to the hot slab, wherein the anvils are urged towards and away from the slab (7) in accordance with a predetermined cycle of movement, each cycle including at least one period during which the anvils are in a position such as to cause the desired reduction in the width of the slab; characterised in that: the method uses eccentric presses for reciprocatively driving the width reduction heads (6) by means of sliders (4); during preforming an end of the slab, the method comprises a step of adjusting each of said width reduction heads (6) in a direction closing the anvils (8) during an opening stroke of the slider (4) to obtain a distance to be reduced by one anvil (8) in a first stage preforming, then effecting the first stage preforming during a closing stroke of the slider (4), thereafter adjusting each of said width reduction heads (6) along its respective slider (4) to obtain a distance according to a desired reduced distance in the same manner as in the first stage preforming and effecting preforming during a closing stroke of the slider (4) in the same manner as in the first stage when required, thereby concomitantly adjusting the position of the anvils relative to the sliders (4) at the commencement of each of said cycles of movement; and during steady width reduction of the slab, the method comprises the steps of setting the distance to be reduced of the slab within a range in which the anvils (8) and the hot slab (7) do not interfere with each other during its advancing, feeding the hot slab (8) during the opening stroke of the slider (4) through a distance determined by the distance to be reduced and the angle of the inclined portion at the entry side, and repeating the cycle for reducing to the desired reduced distance during the closing stroke of the slider (4) to effect the reduction in width progressively. A method according to claim 1 wherein the eccentric presses are driven using eccentric driving means comprising a crankshaft (2) and connecting rod (3), and wherein said preforming further comprises steps of setting a distance between said anvils (8) corresponding to an inner dead point of the crankshaft (2) of each of said driving means at a value somewhat wider than a width of the hot slab (7), then feeding the hot slab (7) to a predetermined position relative to the anvils (8). A press apparatus for reducing the width of a hot slab (7), comprising feeding means (16, 17, 18, 19) for feeding the slab in a feed direction, a pair of anvils (8) adapted to move towards and away from each other in width directions of the hot slab (7), each anvil (8) having a parallel portion (14) substantially parallel to the feed direction of the hot slab (7) and an inclined portion (15) on the entry side in the feed direction, width adjusting means (5, 11, 12, 13) for adjusting the position of the anvils (8), and urging means (2, 3, 4, 6) for urging the anvils (8) towards and away from the slab (7) in accordance with a predetermined cycle of movement; characterised in that: the press apparatus is for carrying out the method according to claim 1 or 2; said urging means comprises eccentric presses for reciprocatively driving by means of sliders (4) width reduction heads attached to each said anvil (8), said width adjusting means (5, 11, 12, 13) being incorporated in said eccentric presses; and said width adjusting means (5, 11, 12, 13) is arranged to adjust each of said width reduction heads (6) in a direction closing the anvils (8) during an opening stroke of the slider (4) to obtain a distance to be reduced by one anvil (8) in a first stage preforming, so that the first stage preforming can be effected during a closing stroke of the slider (4), thereafter to adjust each of said width reduction heads (6) along its respective slider (4) to obtain a distance according to a desired reduced distance in the same manner as in the first stage preforming so that preforming can be effected during a closing stroke of the slider (4) in the same manner as in the first stage when required, thereby concomitantly adjusting the position of the anvils (8) relative to the sliders (7) at the commencement of each of said cycles of movement when preforming an end of the slab, and arranged to make a minimum distance between the anvils (8) equal to the desired reduced distance in steady width reduction of the hot slab (7) by setting the distance to be reduced of the hot slab (7) within a range in which the anvils (8) and the hot slab (7) do not interfere with each other during its advancing; and in that said feeding means (16, 17, 18, 19) is arranged to feed the hot slab (8) during the opening stroke of the slider (4) through a distance determined by the distance to be reduced and the angle of the inclined portion at the entry side. A press apparatus as claimed in claim 3, wherein said urging means comprises in combination a pair of width reduction heads (6) to which the pair of anvils (8) are attached and crankshafts (2) and connecting rods (3) for reciprocatively driving the width reduction heads (6) by means of sliders (4), and said adjusting means comprises a plurality of screw-threaded rods (5) having threaded portions threadedly engaging internally threaded apertures (4a) formed in the slider (4) with one end of each respective rod (5) being fixed to a respective width reduction head (6) and the other end being fixed to width adjustment driving means (11, 12, 13). A press apparatus as claimed in claim 4, wherein said width adjustment driving means comprises in combination splined gears (9) slidably fitted on said other ends of the screw-threaded rods (5) formed with splined grooves (5a), pinions (10) in mesh with said splined gears (9) respectively, universal spindles (11) connected to the pinions (10) respectively, and a driving source (12, 13) for driving the universal spindles (11).

Inventors: KOMORI ATUSHI, NAOI TAKAYUKI, NIHEI MITSUO, NIKAIDO HIDEYUKI, KOMORI, ATUSHI, NAOI, TAKAYUKI, NIHEI, MITSUO, NIKAIDO, HIDEYUKI, KOMORI, ATUSHI C/O HITACHI WORKS, NAOI, TAKAYUKI MIZUSHIMA WORKS KAWASAKI STEEL, NIHEI, MITSUO C/O HITACHI WORKS, NIKAIDO, HIDEYUKI MIZUSHIMA WORKS KAWASAKI STEEL
Applicants: HITACHI LTD, KAWASAKI STEEL CO, HITACHI, LTD., KAWASAKI STEEL CORPORATION
Application year: 1986
Main classification: B21B1
IPC codes: B21B1, B21B15, B21J5