GB2071188A - Steel H-sheet pile and producing method thereof - Google Patents

Abstract

A steel pile having an H-shaped transverse cross-section and having joint portions (4b, 5b, 6b, 7b) respectively disposed at opposite ends of a pair of flanges (1b, 2b) disposed on opposite sides of the centre line (X-X) of the pile and wherein one pair of joint portions (4b, 5b) disposed on one side of the centre line or on opposite sides of the centre line in diametrically opposed relationship is formed into finger joint portions, and the other joint portions (6b, 7b) are formed into overlap joint portions. <IMAGE>

Description

SPECIFICATION Steel H-sheet pile and producing method thereof The present invention relates to a steel H-steel pile being of an H shape in cross section and having joint portions respectively disposed at opposite ends of a pair of flanges opposed to each other with the center line of the H-sheet pile in cross section being interposed between the pair of flanges and a producing method thereof.

There have been voiced for necessity of providing sheet piles having high sectional performance, water leakage preventiveness and workability due to the development in scale of the civil engineering work for constructing a revetment, quay wall, landslide protection, temporary cofferdam or the like. To meet this necessity, heretofore, there have been provided various sheet piles in which joint members are welded to steel pipes and various shape steels each having a large cross section. However, processes of separately producing the main bodies of sheet piles and joint members, and processes of welding the joint members to the main bodies of sheet piles are required for producing these sheet piles, thereby increasing production costs.

Then, there have been proposed steel sheet piles being of various cross sections to be produced only by the rolling process in which the main body of sheet pile is integrally formed with joint members.

Among those steel sheet piles, one which can easily have a high sectional performance and can be rolled with a high efficiency is a steel sheet pile being of an H shape in cross section and having joint portions, which engage joint members of adjacent sheet piles each other, respectively at opposite ends of a pair of flanges opposed to each other with the center line of the H-sheet pile in cross section being interposed between the pair of flanges.Such a steel H-sheet pile is comparatively easily produced because of being free from sweeps and the like during rolling process that which, for example, has such a cross section that joint portions 4, 5 and 6, 7 respectively disposed at opposite ends of a pair of flanges 1, 2 opposed to each other with the center line X-X of the H-sheet pile in cross section being interposed between the pair of flanges are bisymmetrical. However, the occurrence of dispersions in interval A between the right and left joint portions during rolling process and conling process due to the temperature distribution and the like is unavoidable, so that it is very difficult to simultaneously couple the joint portions 4, 6 of the opposite flanges 1, 2 to the joint portions 5, 7 of adjacent sheet piles.Even if the joint portions are coupled to each other, the sheet pile drive-in resistance in value becomes considerably high due to the dispersions in the intervals A of the sheet piles in the longitudinal direction.

Additionally, the above described steel H-sheet piles can be driven in along a straight line, but cannot be driven in along a curved line.

Accordingly, for example, a so-called unilateral finger type steel H-sheet pile has been practically used, in which, as shown in Fig. 2, joint portions 4a, 5a are formed only at opposite ends of a flange 1 a disposed at one side and a flange portion 2a disposed at the other side, is formed with no joint portions.

This unilateral finger type steel H-beam can be easily produced by welding joint members to an ordinary steel H-sheet pile. However, in the case such a unilateral finger type steel H-sheet pile, in which a main body is integrally formed with joint portions, is produced by rolling, the extent of asymmetry in cross section is high, and hence, sweeps, cambers, torsions and the like are frequently caused to the material during rolling and cooling processes, and moreover, since the flange portions 1 a, 2a are different in length, it is difficult to convey the materials on the production line and stack the materials in a H shape.

Since joint portions are formed only on flanges 1 a disposed on one side in this type of sheet piles, it is simple to drive in the sheet piles with the joint portions of the adjacent sheet piles being coupled to each other, however, satisfactory water leakage preventiveness is not obtainable. For instance, in the case sand and soil filled up in the interior 8 of the steel H-sheet pile are dug out for removal and instead concrete or the like is to be filled in the interior 8, depending on the nature of the soil the sand and soil may fall into the interior 8 through a gap 9 formed between the flanges not coupled to each other and digging is difficult to perform, and when the concrete is filled up into the interior, perfect integration between the sheet pile and the concrete cannot be achieved.

The present invention has been developed to obviate the abovedescribed disadvantages and has as its object the provision of a cross-sectional shape of a steel H-sheet pile excellent in workability and water leakage preventiveness and also the provision of a method of efficiently and highly accurately producing a steel H-sheet pile having the abovedescribed cross-sectional shape by use of a group of universal mills.

To achieve the aforesaid object, the steel H-sheet pile according to the present invention is of such an arrangement that, in a steel H-sheet pile having joint portions respectively disposed at opposite ends of a pair of flanges opposed to each other with the center line of the H-sheet pile in cross section being interposed between the pair of flanges, one pair of joint portions disposed at one side or at diagonally symmetrical positions with each other with respect to the center line are formed into finger joint portions, respectively, and the other joint portions opposed to said one pair of joint portions are formed into overlap joint portions, respectively.

The method of producing the abovedescribed steel H-sheet pile according to the present invention is arranged such that, in a process of rolling a beam blank by means of a breakdown mill, a roughing universal mill, a sizing mill and a finishing universal mill, a beam blank prepared by blooming rolling or continuous casting and having a H-shaped cross section symmetrical in the vertical and lateral directions is rolled into an H-shaped beam blank having a socket and projections corresponding to two projecting members forming a finger joint portion at the end of a flange by means of a breakdown mill provided therein with a caliber for shifting the positional relationship between a web and flanges of a beam blank and deforming the beam blank into an asymmetrical H shape and another caliber for forming a socket and projections at one end of the flange.

The method of producing the abovedescribed steel H-sheet pile according to the present invention is arranged such that, in reversing rolling the abovedescribed beam blank in a plurality of passes by means of a group of roughing universal mill consisting of a roughing universal mills and a sizing universal mills, during the first half of the passes, the elongation ratio per pass of the flanges on the opposite sides is made 1.03 times or more higher than that of the web, during the last half of the passes the elongation ratio per pass of the flanges on the opposite sides is made less than 1.03 times that of the web, while the elongation ratio per pass of the flanges during the last half of the passes is set at 1.15 or less.

The method of producing the abovedescribed steel H-sheet pile according to the present invention is arranged such that, in size-rolling the forward end portion of the flange of the aforesaid beam blank by means of a sizing universal mill, the outer surface of the flange is pressed at a reduction ratio of 10% or less by means of vertical rolls of a sizing universal mill, while the forward end portion of the flange is size-rolled by means of horizontal rolls.

The method of producing the abovedescribed steel H-sheet pile according to the present invention is arranged such that, in bending joint portions of the stock, which has been rolled by a group of sizing universal mills, before finishing-rolling by means of a finishing universal mill, the joint portion is bent by means of a joint forming apparatus which is placed in front of finishing universal mill and in which a roller having a projection for determing a position to be bent of the joint portion and a roller having a projection for bending the joint portion are supported by open-sided shafts, respectively, the shafts are secured to the main body of the apparatus through nuts each formed on the inner periphery thereof with threads to be threadably coupled to threads provided on one end portion of the shaft and further formed on the outer periphery thereof with threads having a center different from the center of the threads formed on the inner periphery, so that the rollers can be adjusted in position in the axial and radial directions.

The abovementioned features and object of tne present invention will become apparent with reference to the following description, taken in conjunction with the accompanying drawings, wherein like referenced numerals denote like elements, and in which: Fig. 1 is a sectional view showing the conventional, bisymmetrical and bilateral finger type steel H sheet pile; Fig. 2 is a sectional view showing the conventional unilateral finger type steel H-sheet pile; Fig. 3 is a sectional view showing an example of the steel H-sheet pile according to the present invention; Fig. 4 is an explanatory view showing the state where the steel H-sheet piles shown in Fig. 3 are arranged in an alternately overturned fashion; Fig. 5 is a view of layout of the mills in an embodiment of the present invention;; Fig. 6 is a sectional view showing the beam blank being of a H-shape in cross section, symmetrical in vertical and lateral directions; Fig. 7 is a sectional view showing the beam blank rolled by the break-down mill; Fig. 8 is a sectional view showing the relationship between the caliber of the breakdown mill and the material; Fig. 9 is a sectional view showing the design of the calibers of the breakdown rolls in an embodiment of the present invention; Fig. 10 is a front view showing the essential portions of the calibers of the roughing universal mill; Fig. 11 is a front view showing the essential portions of the calibers of the sizing mill; Fig. 12 is calibers showing the progress of rolling performed by the group of roughing universal mills; Fig. 13 is a sectional view showing the semi product stock rolled by the roughing universal mill;; Fig. 14 is a front view showing the essential portions of the mechanism for forming unevenness at the foot of the projecting piece 11 of the semi product stock rolled by the roughing universal mill; Fig. 1 5 is a front view showing the essential portions of the shape of the ragging at the foot of the projecting piece 11 of the semi product stock rolled by the roughing universal mill; Fig. 16 is a front view showing the essential portions of the flange buckling preventive mechanism in the sizing universal mill according to the present invention; Fig. 17 is a sectional view showing the joint forming device according to the present invention.

Fig. 1 8 is a front view showing the essential portions of the roll calibers of the finishing universal mill; and Figs. 1 9 and 20 are sectional views showing other embodiments of the steel H-sheet pile according to the present invention, respectively.

Description will hereunder be given to the embodiments of the present invention with reference to the present invention.

Firstly, Fig. 3 shows an embodiment of the cross section of the steel H-sheet pile produced according to the present invention. Out of joint portions 4b, 5b and 6b, 7b disposed at opposite ends of flanges 1 b, 2b opposed to each other with the center line X-X of the H-sheet pile in cross section being interposed between the pair of flanges 1 b, 2b, a pair of joint portions 4b, 5b are formed into finger joint portions to be coupled to each other. More particularly, in one pair of joint portions 4b, 5b, one joint portion 4b is formed with a socket 9 formed between projecting pieces corresponding to so-called finger and thumb 10, 11, and the other joint portion 5b is formed with a ball end 12 to be coupled to the socket 9.Thus, the socket 9 of one sheet pile is coupled to the ball end 12 of the adjacent sheet pile, which is repeated successively, thereby forming a wall of sheet piles. As for the other pair of joint portions 6b, 7b, in Fig. 3 for example, the inner surface of the joint portion 6b is overlapped on the outer surface of the joint portion 7b with a gap 1 3 being held therebetween. In this embodiment shown in Fig.

3, the joint portion 5b forming the projecting piece on the coupling side and the joint portion 7b on the overlapping side are symmetrically formed with respect to the center line X-X, so that finger joint portions of every other sheet piles can be disposed not only at the same sides but at the other sides with respect to the center line, i.e. in an alternately overturned fashion, thereby enabling to form a wall of sheet pile.The gap 13 formed between the joint portions 6b and 7b to be overlapped can absorb the dispersions in rolling results, and moreover, is designed to be 2 to 1 Omm so as to keep the dimensions for preventing the fall-in of the soil and sand into the interior of the sheet pile through the gap when the sand and soil filled up in the interior of the sheet pile are dug out and the flow-out of the concrete filled up in the interior. Various shapes of the overlap joint portions may be proposed in addition to the shape as shown in Fig. 3, however, it is preferable to adopt ones as bisymmetrical as possible in shape for the reasons of prevention of sweep of the stock and the like during rolling process.

Referring to Fig. 3, projections 14, 1 5 disposed adjacent the joint portions 5b, 7b are designed to increase the stability when the sheet piles are stacked in an I shape in cross section and also the Hsheet piles are driven in with guide member being applied to the outer surfaces of the flange, and to balance the upper and lower flanges in cross section about a web 3, and further to increase the section modulus of the wall of sheet piles.

The steel H-sheet pile having the cross section according to the present invention is formed at one side thereof with finger joint portions, whereby the workability thereof is high. Further, the steel H-sheet pile is formed at the other side with overlap joint portions, so that the sheet pile can be integrated with concrete filled up in the interior thereof, thereby enabling to form a wall of sheet piles excellent in the water leakage preventiveness. As will be described hereinafter, the sheet pile is rolled by means of the group of universal mills, it is easy to roll the H-sheet piles having the larger height B of the web in cross section, so that the section modulus can be increased.

Description will hereunder be given of the method of producing the steel h-sheet pile according to the present invention with reference to the embodiment having the cross section showing in Fig. 3.

As shown in the layout shown in Fig. 5, the mills used include a blooming mill 21, a breakdown mill 22, a group of roughing universal mills 25 consisting of a roughing universal mill 23 and a sizing mill 24 and a finishing universal mill 26. This layout is identical with the rolling equipments for producing ordinary H-beams which are well known.

The blooming mill 21 rolls a beamblank 29 being of a H shape in cross section, symmetrical in vertical and lateral directions, which is identical with a beam blank for producing an ordinary H bsam well known as shown in Fig. 6. Consequently, detailed description of this part of rolling method will be omitted. This beam blank 29 may be produced by continuous casting.

The beam blank 29 is heated again in a reheating furnace in a section mill, and then, rolled by the breakdown mill 22 into a beam blank 30 to be subsequently rolled by the group of universal mills 25.

As shown in Fig. 7, the beam blank 30 includes flanges 31, 32. The flange 31 at one side is formed at the upper end thereof with a socket 33 corresponding to the socket 9 in the product shown in Fig. 3 and projections 34, 35 corresponding to the projecting pieces 10, 11 of the product shown in Fig. 3, and is bisymmetrical at the lower end thereof corresponding to the bisymmetrical joint portions 5, 7 of the product shown in Fig. 3. The upper end of the flange 32 at the other side is to be rolled into overlap joint portion by the group 25 of the roughing universal mills, and hence, considering the necessary balance in reduction in the lateral direction when it is rolled by the group of roughing universal mills, the flange 32 has no projecting piece corresponding to the projection 35 formed on the side of the finger joint portion.In addition, in Fig. 7, denoted at 36 is a web. Consequently, the beam blank 30 is substantially bisymmetrical on the whole, however, slightly asymmetrical. In other words, the breakdown mill 22 rolls the beam blank 29 symmetrical in the vertical and lateral directions into the beam blank 30 asymmetrical in the vertical and lateral directions.

Here, since calibers formed in a breakdown roll is restricted in number, the beam blank 29 should be rolled into the blank beam 30 by use of calibers as small as possible in number. However, if the beam blank 29 is rolled in a plurality of passes by use of an open pass (open calibers) only as shown in Fig. 8, then from the second pass the elongation of the web 36 becomes greater than the elongations of the flanges 31, 32, with the result that the flanges are pulled by the web in the longitudinal direction, the inner surfaces of the flanges are decreased in the thickness-wise directions and the projection 35 is not filled up in the caliber, thereby causing a considerable dispersion to the shapes and dimensions of the projection 35 in the longitudinal direction.During the following rolling process in the group 25 of universal mills, the projection 35 is rolled by a dead hole. Therefore, if the projection 35 is insufficient in its cross-sectional area as described above at the step of the beam blank 30, then the insufficiency in the dimensions is further enhanced, thus causing a considerable dispersion in dimensions of the projecting piece 11 in the final product shown in Fig. 3. In order to prevent the abovedescribed disadvantage, it is necessary to increase the number of calibers and equalize the elongation ratio of the web to the elongation ratios of the flanges in the respective calibers. However, a roll cannot be formed therein with many calibers, and hence in order to increase the number of calibers, it leads to the necessity of increasing the number of the mills.

Now, according to the present invention, the breakdown mill 21 has rolls formed with a caliber 38 and another caliber 39. A box pass 40 is intended for correcting an overfill into a gap 42 formed between the rolls when rolling is effected by the caliber 38, and corrects the overfill in such a way that the blank is turned through 900 and passed through the box pass 40. The beam blank 29 symmetrical in the vertical and lateral directions shown in Fig. 6 is firstly rolled into the beam blank asymmetrical in the vertical directions and substantially bisymmetrical by use of the caliber 38 in a plurality of passes.This roRing by use of the caliber 38 contemplates to cause a shearing deformation between the web 43 and the flanges 44,45 as shown in Fig. 6 to thereby shift the positional relationship between the web 43 and the flanges 44, 45 and tends to cause lowing (turn up or down) and the like to the blank during a first pass. However, the sweeps and the like can be satisfactorily corrected by manipulators provided in front and at the back of the mill. In the caliber 38, the blank is rolled to a predetermined web thickness (50mm in an example) in a plurality of passes (6 passes except for the overfill correcting pass in the example).At this step, metal flows within the cross section of the blank can be effected comparatively freely, and the junction portions of the web 43a and the flanges 44a, 45a of the caliber 38 are each formed into a shape being smooth and having a large radius of curvature, thereby eliminating the disadvantage of insufficient filling of the flanges 44a, 45a into the calibers. The blank, in which its web has been decreased in thickness to a predetermined thickness by means of the caliber 38 and which has been formed into a H-shaped cross section asymmetrical in the vertical direction, is rolled in 1 to 3 passes (if there are allowances in the strength of rolls and the motor capacity, one pass is desirable.) By means of the caliber 39 in one operation.If the caliber 38 is designed to have elongation ratios for the web 36a and the flanges 31 a, 32a being equal to each other when rolled in the caliber 39, then the decreases in thickness of the flanges 31 a, 32a in the caliber 39 do not occur, thus enabling to obtain the cross sections having a low dispersion in the direction of rolling. It is further advantageous to form a preparatory step forming portion 47 in the caliber 38 so as to facilitate forming of the projecting piece 35 in the caliber 39.

As described above, the breakdown mill 22 is provided with the caliber 38 for rolling the beam blank symmetrical in the vertical and lateral directions into one asymmetrical in the vertical and lateral directions so as to regulate the reduction balance of the respective portions of the beam blank during the reduction to be effected in the following caliber 39, to thereby obtain the beam blank 30 having the predetermined shape, and can roll the ordinary beam blank 29 symmetrical in the vertical and lateral directions into the beam blank 30 to be fed to the group 25 of the universal mills disposed following this breakdown mill 22.

The beam blank 30, which has been rolled by the breakdown mill 22, is sent to the group 25 of the roughing universal mills consisting of the roughing universal mill 23 and the sizing mill 24, where it is reciprocatingly rolled in plurality of passes.

As shown in Fig. 10, the roughing universal mill 23 includes upper and lower horizontal rolls 51, 52 and vertical rolls 53, 54 disposed to the right and left of the horizontal rolls 51, 52 and rolls a web 3c by the outer peripheries of the upper and lower horizontal rolls 51, 52 and flanges 1 c, 2c by the side surfaces of the upper and lower horizontal rolls 51, 52 and the outer peripheries of the vertical rolls 53, 54 in the same manner as in rolling an ordinary H beam. The substantial difference between the rolling of an ordinary H beam and this rolling resides in the rolling of a projection 11 c, which is formed by a groove 55 formed in the upper horizontal roll 51 in this rolling.A projection 1 0c and other joint portions 5c, 6e and 7c are rolled by the side surfaces of the horizontal rolls 51,52 and the outer peripheries of the vertical rolls 53, 54 in the same manner as in rolling the flanges 1 c, 2c. The sizing mill 24 disposed behind or in front of the roughing universal mill 23 includes an upper caliber roll (grooved roll) 61 and a lower caliber roll 62 as shown in Fig. 11, and, in the same manner as in edging pass or ordinary H beam rolling, flange end portions 63, 64 and 65, 66, which have not come into contact with rolls when rolled in the roughing universal mill 23. The beam blank 30 shown in Fig. 7 is rolled by the roughing universal mill 23 and the sizing mill 24 in a plurality of passes as shown in Figs. 1 2A through 1 2F and finally turned into a semi final product 60 as shown in Fig. 1 3.

The rollings effected by the roughing universal mills 25 are done substantially bisymmetrically, thus causing little sweep to the blanks. The projection 1 Oc and joint portions 5c, 6e and 7c of the beam blank rolled by the group 25 of the roughing universal mills are extend bybeing decreased in thickness by the positional adjustments of the vertical rolls during the respective passes in the universal mill 22, and the projection 11 c is formed by filling up the blank into the groove 55 formed in the upper horizontal roll 51.However, the reduction acting on this portion of the cross section is limited only to the movement of the upper horizontal roll 51, and, since the decrease in the cross-sectional area due to the elongation of the entire cross section in the longitudinal direction of the rolling is greater than the decrease in the cross-sectional area due to the movement of the upper horizontal roll 51, the projection 11 c tends to be insufficiently filled in the caliber.

This projection 11 c is easily filled up in the groove 55 by metal flows coming from adjacent portions subjected to a high reduction during the first half step of passes where the entire cross section is comparatively large and the degree of freedom for the metal flows in the cross section is high, however, the adverse effect of the decrease in the cross section due to the elongation of the entire cross section becomes greater during the last half step of passes where the degree of freedom for the metal flows in the cross section comes to be low, thus tending to insufficient filling of the projection 11 c in the groove 55.More specifically, if the reduction on the flanges in value is made greater than the reduction on the web during the first half step of passes where the degree of freedom for the metal flows is high, then the flanges tend to extend more than the web does, however, the web and the flanges are integrally formed, so that the flanges cannot extend alone separately of the web, and, metal flows occur by the amount disturbed in elongation in the direction of the width of the flange (the vertical direction in Fig.10). Consequently, if reduction is applied to the beam blank placed under the abovedescribed condition by the horizontal roll 51, then the blank can be filled up in the groove 55.

According to the various types of experiments made by the present inventor, it has been affirmed that, in order to cause metal flows to occur in the widthwise direction of the flange 1 c during the first half step of passes, it is necessary to make the elongation ratio of the entire cross section of the flanges to be 1.03 times or more higher than that of the web, though it differs depending on the radio in cross section between the web and flanges. During the step where the flanges are decreased in thickness, the adverse effect of the frictional force between the blank and the roll acting on the surface of the blank reaches to the interior of the flanges, whereby the metal flows of the blank tend to be affected.A frictional force directed toward the web acts on the interior and the projection 11 c of the flanges due to rotation of the horizontal roll 51, whereby the spreading in the widthwise direction of the flanges is disturbed, so that no advantage can be obtained even if the elongation ratio of the flanges is made greater than that of the web.

On the other hand, since the flanges 1 a, 2b of the product of the steel H-sheet pile shown in Fig. 3 is made greater in thickness than the web 3b so as to improve the section modulus, if the balance in elongation during rolling is taken into consideration, the rolling reduction on the flanges is constantly greater in value than that of the web in each pass. Consequently, in the roughing universal mill 23, unless the diameter of the vertical roll 53 is made by far smaller than the diameters of the horizontal rolls 51, 52, or the axis of the vertical roll 53 is shifted from the axes of the horizontal rolls 51, 52, usually reduction on the outer surface of the flanges by the vertical roll 53 is begun before reduction on the web 3c and the projection 11 c by the horizontal roll 51 is begun. More specifically, as shown in Fig.

14, at the time E when the vertical roll 53 begins to contact the outer surface of the flange, the horizontal rolls 51, 52 are at the positions G with a gap 58 being formed between a projection of roll 56 and the blank, and, by the time H when the projection 56 of the horizontal roll comes into contact with the blank, the outer surface of the flange is reduced to a line F. By this reduction, the foot of the projection 1 Oc is pushed into the gap 58 and the projection 11 is also pushed to the right.The ratio of the value of the projection 11 c being pushed rightward to the movement X of the vertical roll increases during the last half step passes where the projection 11 c tends to be insufficiently filled in the groove 55 during the last haif step of passes, a ragged step 57 as shown in Fig. 1 5 is formed at the foot of the projection 11 c in every pass. The requirement for high accuracies in the shape and dimensions of the projection 11 c necessitates to take a measure for this ragging. For this purpose, it is necessary that the contact beginning points between the vertical roll with the blank and the horizontal rolls with the blank are made to draw as close as possible to each other and the reduction X on the flanges is made as small as possible in value.If the contact beginning points between the vertical roll with the blank and the horizontal rolls with the blank are made to draw as close as possible to each other, then the elongation ratio of the web tends to become greater than the elongation ratio of the flanges because the web is smaller in thickness than the flanges. However, when the elongation ratio of the web becomes greater than the elongation ratio of the flanges, because the web is smaller in thickness than the flanges, the web tends to be disturbed in its elongation by the flanges to thereby cause buckling rather than that it pulls the flanges and extend. On the other hand, when the reduction on the flanges increases in value, the gap 58 shown in Fig. 14 becomes greater. Consequently, it is preferable that the reduction on the flanges is made as small as possible in value and the reduction by the horizontal roll, i.e., the reduction on the web is made as great as possible within a range that the elongation ratio of the web does not exceed the elongation ratio of the flanges.

According to the various types of experiments made by the present inventor, it has been affirmed that, if the elongation ratio of the flanges during the last half step of passes is made 1.1 5 or less per pass, then the difference between the elongation ratio of the projection 11 c and that of the remaining portion becomes smaller in absolute value and the reduction by the vertical roll 53 becomes smaller, so that such disadvantage including the decrease of the projection 11 c in thickness and the ragged step at the foot thereof can be obviated to a considerable extent. Further, if the ratio between the elongation ratio of the flanges and the elongation ratio of the web is set at 1.0 N 1.03, then the gap 58 shown in Fig. 14 becomes smaller and the advantage of improving the ragged step is further enhanced.It has been affirmed that, on the contrary, if the elongation ratio of the flanges is set at 1.1 5 or more and the elongation ratio of the web at 1.03 or more, then the projection 11 c becomes by far worse in shape after rolling.

As described above, during the first half step of passes the elongation ratio of the flanges is preferably made by far greater than the elongation ratio of the web to promote the metal flows in the widthwise direction of the flanges, however, on the contrary, during the last half step of passes, the elongation of the flanges is preferably controlled to the utmost, to thereby cause the elongation ratio of the web and the elongation ratio of the flanges to draw as close as to each other. The mean value of the total number of the passes performed by the group of the universal mills may be regarded as the borderline between the first and last half steps of passes, and the elongation ratio of the flanges is preferably decreased with the progress of passes. Table 1 shows an example of the pass schedule.

TABLE 1 Example of Pass Schedule in Group of Universal Rolling Mills

Elongation ratio of flange Average Average Elongation Elongation thickness thickness ratio of ratio of Elongation ratio Pass No. of web of flange web flange of web 59mm 158mm 1 48 146 1.042 1.082 1.039 2 44 129 1.091 1.132 1.037 3 39.6 112 1.111 1.152 1.037 4 35.6 97 1.112 1.155 1.038 5 31.9 84 1.116 1.155 1.035 6 28.5 72.8 1.119 1.154 1.031 7 25.5 63.2 1.118 1.152 1.031 8 22.9 55.2 1.114 1.145 1.028 9 20.6 48.5 1.112 1.138 1.024 10 18.6 42.8 1.108 1.133 1.023 11 16.8 37.9 1.107 1.129 1.020 12 15.2 33.7 1.105 1.125 1.018 13 13.8 30.1 1.101 1.120 1.016 14 12.6 27.1 1.095 1.111 1.014 15 11.6 24.6 1.086 1.102 1.014 16 10.8 22.6 1.074 1.088 1.013 17 10.2 21.1 1.059 1.071 1.012 Even if the measures as described above are taken, as the final pass approaches, the projection 11 c is insufficiently filled in the groove 55 of the roll and formed at the foot thereof a ragged step more or less.Hence, it is preferable that the curve formed at the forward end of the projection 56 of the upper horizontal roll is made as the ragged steps are inconspicuous even if the step may be formed thereon.

The contour of the cross section of the projection 11 c after the final pass is substantially analogous to the contour of the cross section of the groove 55, and the cross-sectional area thereof was substantially 7/10 of the cross-sectional area of the groove 55 in the embodiment, though it varies depending on the difference in elongation ratio between the projection 11 c and the remaining portion. Consequently, if the shape and the dimensions of the groove 55 are made to take the abovedescribed decrease into account, then aimed shape and dimensions may be obtained after the rolling process.

More particularly, according to the present invention, in reversingly rolling the beam blank in a plurality of passes by means of the group of roughing universal mills including a roughing universal mill and a sizing mill, during the first half step of passes the elongation ratio per pass of the flanges as a whole is made 1.03 times or more higher than the elongation ratio of the web, during the last half step of passes 1.03 times or less, during the last half step of passes the elongation ratio per pass of the flanges is set at 1.15 or less, the projection pieces are rolled into ones having aimed shape and dimensions by means of the caliber, and the malformation can be prevented and the accuracies in dimensions can be improved.

In rolling the beam blank by means of the group 25 of the universal mills as described above, the sizing mill 24 disposed behind or in front of the universal mill 23 acts reduction on the forward ends 63, 64, 65 and 66 of the projection 1 Oc, joint portions 5c, 6e and 7c, all of which have not come into contact with the rolls in the roughing universal mill 23 as described above, and, when reduction forces P1, P2, P3 and P5 are applied to these forward ends 63, 64, 65 and 66, respectively, a bending moment acts on the flanges 1 c, 2c toward the sides of the flanges not being in contact with rolls 61, 62, whereby such a tendency occurs that the positions of contact between the aforesaid forward ends and the rolls 61, 62 are shifted.The tendency occurs most often during the final pass where the flange is decreased in thickness, which leads to dispersions in the shapes and dimensions of these forward ends of the flange as the final product. The dispersions in the shapes and dimensions in these forward ends should be minimized because they form the joint portions of the steel H-sheet pile.

Therefore, according to the present invention, in place of the sizing mill 24 of the group 25 of the universal mills, a universai mill 90 as shown in Fig. 16 other than the two-high mill. As for the shapes of this universal mill 90, horizontal rolls 91,92 are substantially identical in shape with the rolls 61,62 of the aforesaid sizing mill as shown in Fig. 16, and vertical rolls 93, 94 are formed such that they are interposed between the horizontal rolls 91, 92 to effect reduction on the outer surface of the flanges except for the forward ends thereof. The forward ends 63, 64, 65 and 66 of the joint portions at the ends of the flanges, which have not been in contact with the rolls in the universal mill 23 are size-rolled by the horizontal rolls 91, 92 of the universal mill 90.At this time, the vertical rolls 93, 94 chiefly aim at preventing the flanges from falling to the outer side, and, in principle, no active reduction on the flange is not effected. However, light reduction of 1 or less may be effected for the purposes of decreasing the number of passes and improving prevention of falls. If a reduction more than above is effected, then the forward ends are bulged out into roll gaps 95, 96, 97 and 98, the reduction on the forward ends by means of the vertical rolls of the universal mill during the succeeding passes is increased in value, thereby resulting in unstable shapes and dimensions of the forward ends.The abvedescribed sizerolling method may be applied not only to the case in which the two universal mills are continuously disposed as in this embodiment but also to the case, when three or more universal mills are continuously disposed for unidirectional or reciprocating rolling, one or more of the universal mills are useil for size-rolling the forward ends of the flanges.

Needless to say, the abovedescribed method of preventing the flanges from falling may be advantageously applied to a beam blank in which the accuracies in shapes and dimensions of the forward ends in the joint portions and the like are valued highly, and further, the method is advantageous in improving the shapes of the forward ends when it is applied to rolling of ordinary H beams.

The semi-final product, which has been rolled to the cross-sectional shape 50 as shown in Fig. 1 3 in the group 25 of the roughing universal mills, is finally rolled by the finishing universal mill 26 and a joint forming apparatus 27.

As shown in Fig.17, the joint forming apparatus 27 includes an inner roll 100 having a ridge 102 for determining a bending position for the projecting piece 10 and an outer roll 101 having a ridge 103 for pressing and bending the projecting piece 10. The rolls 100, 101 can rotate about rotary shafts 108, 109, respectively, through bearings 104, 105, 106 and 107, however, are solidly secured to the shafts so as not to move in the axial direction of the rotary shafts. A composite bearing between a radial bearing and a thrust bearing a conical roller bearing are preferably used as the bearings 104, 105, 106 and 107 because these bearings are subjected to load acting on the roll in the radial and axial directions. Threads are formed on the outer peripheries of ends of the shafts 1 08, 1 09 and are engaged with internal threads of nuts 110, 111. Threads 114, 11 5 having centers of threads different from those of the internai threads are formed on the outer peripheries of the nuts 110, 111 are threadably coupled to threaded portion provided on the main body 116 of the apparatus so that the rolls can be open-sidedly supported by the main body.Consequently, the positions of the rolls 100, 101 in the axial direction can be adjusted such that the shafts 108,109 are rotated by means of threads to move in the axial directions thereof, and the movements of the rolls in the radial directions can be obtained such that the centers of the shafts 108,109 are moved about the centers of the external threads 114, 11 5 of the nuts 110, 111. The apparatus, being simple in mechanism, can be rendered compact, and easily solidly secured to a rest bar or the like in front of the mill. By securing this apparatus with the rolls for bending the joint portions, the accuracies in bending the joint portions can be improved to a considerable extent.

In this embodiment, two sets of the rolls are continuously provided to carry out a bending work in two steps, however, the number of steps of bending can be increased to further improve the accuracies of bending.

The semi-final product, whose projecting piece i O is bent in the joint forming apparatus 27, is regulated in its contour in the finishing universal mill 26 as shown in Fig. 1 8. At this time, constrictions 120, 121 require for the joint portion forming the pivot are formed. If the constrictions 120, 1 21 are previously formed in the roughing universal mill 23, then the constructions thus formed are subjected to bending deformation during reduction of the forward ends in the sizing mill 24, thereby deteriorating the accuracies in the shapes and dimensions.

Through the abovedescribed process, the steel H-sheet pile has been rolled in this embodiment.

Such a version may be thought of that two or more groups 25 of the roughing universal mill in this embodiment are used, however, the arrangement in this embodiment is so satisfactory that the steel Hsheet pile can be efficiently and highly accurately rolled with the minimum number of the mills.

Description will hereunder be given of steel H-sheet piles 130, 140 respectively shown in Figs 1 9 and 20 as other embodiments of the steel H-sheet piles according to this embodiment.

As shown in Fig. 1 9, the steel H-sheet pile 130 is constructed such that joint portions 131, 1 32 are formed into ones being identical in shape with each other and symmetrical with respect to the center line X-X, a joint portion 1 33 is formed with an outer overlap surface 1 36 to be overlapped on an inner overlap surface 1 34 formed on the joint portion 131 of an adjacent steel H-sheet pile 1 30 through a proper gap 135, and the joint portions 131 is formed with an inner overlap surface 134 to be overlapped on the outer overlap surface 136 formed on the joint portion 133 of an adjacent steel Hsheet pile 130.

As shown in Fig. 20, the steel H-sheet pile 140 is constructed such that joint portions 141, 142 are formed into ones different in shape from each other, a joint portion 143 is formed with an outer overlap surface 146 to be overlapped on an inner overlap surface 144 formed on the joint portion 141 of an adjacent steel H-sheet pile 140 through a proper gap 145, and the joint portion 141 is formed with an inner overlap surface 144 to be overlapped on an outer overlap surface 146 formed on the joint portion 143 of an adjacent H-sheet pile 140 through a proper gap 147.

According to the present invention, a steel H-sheet pile having a high sectional performance and excellent in workability and water leakage preventiveness can be efficiently and highly accurately produced by means of with the rolling equipment identical with one used in rolling ordinary H beams and a small number of additional apparatuses.

The additional apparatuses for use in rolling this steel H-sheet pile and the method of rolling same may be applied to the production of the other shape steels having flanges.

It should be apparent to one skilled in the art that the abovedescribed embodiments are merely illustrative of but a few of the many possible specific embodiments of the present invention. Numerous and varied other arrangements can be readily devised by those skilled in the art without departing from the spirit and scope of the invention.

Claims (8)

1. A steel H-sheet pile having joint portions respectively disposed at opposite ends of a pair of flanges opposed to each other with the center line of said H-sheet pile in cross section being interposed between said pair of flanges, wherein one pair of joint portions disposed at one side or at diagonally symmetrical positions with each other with respect to the center line are formed into finger joint portions, and the other joint portions opposed to said one pair of the joint portions are formed into overlap joint portions.

2. A steel H-sheet pile according to claim 1, and having joint portions respectively disposed at opposite ends of a pair of flanges opposed to each other with the center line of said H-sheet pile in cross section being interposed between said pair of flanges, wherein one of the flanges is provided at one end thereof with a channel defined by two projecting pieces and at the other end thereof with a projection shaped and arranged to be engaged and interlocked, in use, with the said channel of an adjoining pile.

and opposite ends of the other of the flanges are formed into overlap joint portions.

3. A method of producing a steel H-sheet pile wherein, in a process of rolling a beain blank by means of a breakdown mill, a roughing universal mill, a sizing mill and a finishing universal mill, an Hshaped beam blank formed at each end of flanges thereof with a socket and projections corresponding two projecting pieces forming a finger joint portion of said steel H-sheet pile is rolled by means of a breakdown mill having calibers for changing a beam blank prepared by blooming rolling or continuous casting and being of an H-shape in cross section and symmetrical in the vertical and lateral directions into an asymmetrical H-shaped beam blank through shifting the positional relationship between a web and flanges and calibers for forming a socket and projections at one end of a flange.

4. A method of producing a steel H-sheet pile as set forth in claim 3, wherein, in reciprocatingly rolling a beam blank in plurality of passes by means of a group of roughing universal mills including a roughging universal mill and a sizing mill, during the first half step of passes the elongation ratio per pass of the flanges as a whole is made 1.03 times or more higher than the elongation ratio of the web, during the last half step of passes 1.03 times or less, and during the last half step of passes the elongation ratio per pass of the flanges is set at 1.15 or less.

5. A method of producing a steel H-sheet pile as set forth in claim 4, wherein in rolling a beam blank by means of a sizing mill the outer surface of the flange is pressed at a reduction ratio of 10% or less per pass by means of verical rolls of a universal sizing mill, while the forward end portion of the flange is size-rolled by means of horizontal rolls.

6. A method of producing a steel H-sheet pile as set forth in claim 5, wherein, in bending joint portions before finish-rolling the beam blank, which has been rolled by a group of roughing universal mills, by means of a finishing universal mill, the joint portion is bent by means of a joint forming device in which a roller having a projection for determining a position to be bent of the joint portion and a roller having a projection for bending the joint portion are supported by open-sided shafts, respectively, the shafts are secured to the main body of the apparatus through nuts each formed on the inner periphery thereof with threads to be threadably coupled to threads provided on one end portion of the shaft and further formed on the outer periphery thereof with threads having a center different from the center of the threads formed on the inner periphery, so that the rollers can be adjusted in position in the axial and radial directions.

7. A steel H-sheet pile substantially as hereinbefore described with reference to the accompanying drawings.

8. A method of producing a steel H-sheet pile which method is substantially as hereinbefore described with reference to the accompanying drawings.