Patent Grant
9636724
The present invention generally relates to a method for hot rolling Z-section sheet piles.
Steel sheet piles are long structural sections provided with an interlocking system that allows building continuous retaining walls. The most common sheet pile sections are: Z-sections, U-sections, Ω-sections, flat-web sections and H or double-T sections.
Z-section sheet piles include a first flange, a second flange, which is substantially parallel to the first flange, an inclined web, a first corner joining the web to the first flange, a second corner joining the web to the second flange, wherein each of the corners has an opening angle α greater than 90°, preferably in the range of 110° to 140°. The longitudinal edges of the flanges are generally equipped with coupling means for interlocking purposes. In distinct contrast to other sheet pile sections, Z-section sheet piles do not have a plane of symmetry.
It is well known in the art to produce Z-section sheet piles by a hot rolling process, starting from slabs or, more recently, from beam blanks. Different methods for hot rolling Z-section sheet piles are e.g. disclosed in following documents: U.S. Pat. No. 4,291,564, EP 0284827 A2, EP 0890395 A1, DE 2529405 A, JP 4/288903 A and U.S. Pat. No. 5,671,630.
U.S. Pat. No. 5,671,630 discloses a method for rolling such Z-section sheet piles from a beam blank. According to this method, a preform of the sheet pile is rolled with curved preforms of the web and the flanges. The curved preform of the web comprises: two web/flange transition sections, which are substantially flat sections parallel to the rolling plane; a middle section, which is a substantially flat section defining an angle of about 60° with the rolling plane; and two connecting bows, connecting the web/flange transition sections to the oblique middle section. The substantially “J”-shaped preforms of the flanges allow rolling the coupling means close to the neutral rolling plane. In a last rolling step, the curved preforms of the web and the flanges are straightened to form the finished Z-section sheet pile.
It is well known in the art that grooved rolls used for rolling Z-section sheet-piles have a relatively short lifetime. Due to the absence of mirror symmetry in their section, one has to produce one side of the Z-section sheet pile in a deep groove of the upper roll and the other side in a deep groove of the lower roll. Such extreme roll gap contours result in that the roll surfaces are rapidly worn out and in that possibilities for their reworking are rather limited. They also increase the risk of a roll fracture.
There is consequently a need for a method for rolling a Z-section sheet pile in which the rolls have a longer lifetime and are less exposed to a roll fracture.
The invention proposes a method for hot rolling a Z-section sheet pile having a first flange, a second flange, which is substantially parallel to the first flange, an inclined web, a first corner joining the web to the first flange, a second corner joining the web to the second flange, wherein each of the corners has an opening angle α greater than 90°, preferably in the range of 110° to 140°. The proposed method comprises the steps of: (1) rolling a curved preform of the web in successive roll gaps defined by at least one roll pair comprising a grooved upper roll and a grooved lower roll, wherein a preform of the first corner and an adjoining first part of the curved preform of the web are formed in a first groove of the upper roll, in which the latter has e.g. its minimum diameter, and a preform of the second corner and an adjoining second part of the curved preform of the web are formed in a first groove of the lower roll, in which the latter has e.g. its minimum diameter; and (2) subsequently straightening the curved preform of the web between an upper straightening roll and a lower straightening roll. In accordance with one aspect of the present invention, at least in the last roll gaps rolling the curved preform of the web, the diameter of the lower roll decreases in a discontinuous manner in the interval between the first groove in the upper roll and the first groove in the lower roll, and the diameter of the upper roll increases in a complementary manner. Decreasing in a discontinuous manner means that the diameter of the lower roll does not continuously decrease; i.e. there are intermediate portions of the lower roll in the concerned interval, in which the initially decreasing diameter stays substantially constant, and/or in which it increases before it decreases again. In other words, in the interval between the first groove in the upper roll and the first groove in the lower roll, the diameter of the lower roll decreases e.g. in a stepped manner and/or in an undulated manner. It follows that less vertical space is required for rolling the preform of the web; i.e. the minimum diameters of the two rolls may be bigger than with any prior art method of rolling Z-shaped sheet-piles. Consequently, the roll gap contour can be reworked more often, before the minimum diameters of the rolls decrease beyond a limit value. Furthermore, less deep grooves in the rolls also result in smaller rolling torques and in more equal surface speeds along the roll gap contour, i.e. in less mechanical wear of the surfaces of the rolls. In summary, with the proposed method, the rolls wear out less faster and must be reworked less often, but—due to a bigger minimum diameter—can even be reworked more often than with any prior art method for rolling Z-section sheet piles. Last but not least, less deep grooves in the rolls also substantially reduce the risk of a roll fracture. Consequently, with the proposed method, expected total life-time of the rolls can be substantially increased. Finally, it will further be appreciated that the proposed method allows using a relatively thin slab as a starting product for rolling a Z-section sheet pile.
In a preferred embodiment, the diameter of the lower roll decreases, in the interval between the first groove in the upper roll and the first groove in the lower roll, in a an undulated manner, so as to have in this interval at least one intermediate maximum value and one intermediate minimum value. This means e.g. that a third part of the curved preform of the web, which is located between the first part and the second part, is formed partly in a second groove of the lower roll, and partly in a second groove of the upper roll. Due to the fact that rolling of the curved preform of the web is allotted onto at least two grooves in the upper roll and at least two grooves in the lower roll, these grooves may be less deep, i.e. the minimum diameters of the two rolls may be bigger.
In a further embodiment, in the interval between the first groove in the upper roll and the first groove in the lower roll, the diameter of the lower roll decreases then stays constant, before further decreasing. This means e.g. that a third part of the curved preform of the web, which is located between the first part and the second part, is formed between substantially cylindrical portions of the upper roll and the lower roll. Due to the fact that the middle section of the curved preform of the web is rolled—at least partly—between substantially cylindrical roll sections, less vertical space is required for rolling the preform of the web; i.e. the minimum diameters of the two rolls may be bigger than with any prior art method of rolling Z-shaped sheet-piles.
If the centre line of a roll is defined as being the axis (line) about which the roll rotates (i.e. the line passing through the centres of the two bearing journals of the roll) and the nominal diameter of a roll in a roll pair is defined as being the minimum vertical distance between the centre lines of the rolls of the roll pair, the minimum diameter of the lower roll in its—aforementioned—second groove is preferably smaller than the nominal diameter of the lower roll and preferably bigger than the minimum diameter of the lower roll in its first groove; and/or the minimum diameter of the upper roll in its—aforementioned—second groove is preferably smaller than the nominal diameter of the upper roll and preferably bigger than the minimum diameter of the upper roll in its first groove.
Furthermore, if:
If:
In a preferred embodiment, in the first groove of the upper roll and/or lower roll, the bottom surface is formed by a substantially cylindrical surface; and/or in the second groove (if present) of the upper roll and/or lower roll, the bottom surface is formed by a concavely curved surface.
In a preferred embodiment: in the first groove of the upper roll, respectively of the lower roll, the outer flank surface is formed by a conical surface defining an angle α1 in the range of 55° to 75°, with a cylindrical reference surface centred on the centre line of the upper roll, respectively of the lower roll; and/or in the first groove of the upper roll, respectively of the lower roll, the inner flank surface is formed by a conical surface defining an angle in the range of 45° to 65°, with a cylindrical reference surface centred on the centre line of the upper roll, respectively of the lower roll. The connection between the conical inner flank surface and the substantially cylindrical bottom surface is advantageously a concavely curved transition surface.
In a preferred embodiment, the third part of the curved preform of the web has—in a cross-section—substantially the form of a letter “S” tilted by 90°, and forms a wave trough and a wave crest.
If a neutral rolling plane is defined as a plane parallel to the centre lines of the upper and lower roll of a roll pair and located at half the distance between these centre lines; and if the first flange (i.e. the flange adjacent to the first corner) has a first coupling means, preferably a hook-shaped coupling means, along its free end, then a preform of this first coupling means is advantageously rolled below the neutral rolling plane, wherein the minimum diameter of the lower roll in this region is bigger than or equal to the minimum diameter of the lower roll in its first groove. Similarly, if the second flange (i.e. the flange adjacent to the second corner) has a second coupling means, preferably a claw-shaped coupling means, along its free end, then a preform of this second coupling means is advantageously rolled above the neutral rolling plane, wherein the minimum diameter of the upper roll in this region is bigger than or equal to the minimum diameter of the upper roll in its first groove.
Before the final straightening step, the rolled preform advantageously comprises:
The straightening of this preform then takes place between an upper straightening roll and a lower straightening roll. The lower straightening roll advantageously includes: a groove for receiving the first coupling means of the straightened sheet pile; a first conical section for entering in contact with the inner side of the first flange of the straightened sheet pile over substantially the whole width of the inner side; a second conical section for entering in contact with one side of the web of the straightened sheet pile over substantially the whole width of the web; and a third conical section for entering in contact with the outer side of the second flange of the straightened sheet pile over substantially the whole width of the outer side. The upper straightening roll advantageously includes: a first conical section for entering in contact with the outer side of the first flange of the straightened sheet pile over substantially the whole width of the outer side; a second conical section for entering in contact with the other side of the web of the straightened sheet pile over substantially the whole width of the web; a third conical section for entering in contact with the inner side of the second flange of the straightened sheet pile over substantially the whole width of the inner side; and a groove for receiving the second coupling means of the straightened sheet pile. When the preform to be straightened is introduced between the upper straightening roll and the lower straightening roll: the curved preform of the first flange preferably first rests with a convex corner portion against the first conical section of the lower straightening roll; the undulated preform of the web preferably first rests with its substantially flat first part against the second conical section of the upper straightening roll and with its substantially flat second part against the second conical section of the lower straightening roll, wherein the at least one wave trough and one wave crest are preferably arranged in the roll gap contour formed between the second conical section of the lower straightening roll and the second conical section of the upper straightening roll, without touching the latter; and the curved preform of the second flange preferably first rests with a convex corner portion against the third conical section of the upper straightening roll.
Before the rolled preform is introduced between the lower and upper straightening rolls, it is preferably rotated about a longitudinal axis by an angle in the range between 5° and 45°; preferably so that the substantially flat first part and the substantially flat second part of the undulated preform of the web are (if they exist) substantially parallel to a cone generator of the second conical section of the upper or lower straightening roll.
If a neutral rolling plane for the upper straightening roll and lower straightening roll is defined as a plane parallel to the centre lines of both straightening rolls and located at half the distance between these centre lines; then, the connections between the flange ends and the coupling means are preferably located close to the neutral rolling plane.
When the preform to be straightened is introduced between the upper straightening roll and the lower straightening roll: the convex corner portion of the curved preform of the first flange is advantageously guided along the first conical section of the lower straightening roll towards the groove receiving the first coupling means; the convex corner portion of the curved preform of the second flange is advantageously guided along the third conical section of the upper straightening roll towards the groove receiving the second coupling means; the substantially flat first part of the undulated preform of the web is advantageously guided along the second conical section of the upper straightening roll towards the first conical section of the upper straightening roll; the substantially flat second part of the undulated preform of the web is advantageously guided along the second conical section of the lower straightening roll towards the third conical section of the lower straightening roll. The at least one wave trough and the at least one wave crest are initially arranged in the roll gap contour formed between the second conical section of the lower straightening roll and the second conical section of the upper straightening roll, preferably without contacting the conical sections.
If AB is the distance in the rolled preform before straightening between the centre A of the preform of the first corner and the centre B of the preform of the preform of the second corner, and A′B′ is the distance in the final sheet pile between the centre A′ of the first corner and the centre B′ of the second corner; then the ratio A′B′/AB is preferably in the range of 1.05 and 1.25.
The afore-described and other features, aspects and advantages of the invention will be better understood with regard to the following description of an embodiment of the invention and upon reference to the attached drawings, wherein:
In the sheet pile 10 of
The grooves in the upper roll 26 and lower roll 28 cooperate to define a roll gap with a shaped contour and, possibly, an adjustable height. In
It will further be noted that one pair of rolls 26, 28 generally defines several (most often three) adjoining roll gaps; but that several such roll pairs are nevertheless required for defining all the roll gap contours used for progressively transforming the starting product into the finished Z-section sheet pile. However, for understanding the proposed rolling method, it is not really important to know by which roll pair or in which roll stand, a particular roll gap contour C01A, C01B, C02A, C02B, C03, C04, . . . C08, C09, C10 is defined. Therefore, reference number 26 is systematically used to generally identify any upper roll, and reference number 28 is systematically used to generally identify any lower roll used in the proposed method.
It will be noted that the proposed method may be carried out with either a beam blank or a slab as a starting product. Basically, only the two first roll gap contours will differ depending on whether the starting product is a beam blank or slab. Thus, in
In the roll gap contour C01A, the initial shape of a beam blank 30 is shown. It will be noted that this beam blank 30 is supported on a slightly inclined roll table (not shown), so that its web 32 is, at the entrance of the roll gap contour C01A, slightly inclined with regard to a horizontal plane 34. Thus, at the entrance of the roll gap contour C01A, the web part 32 of the beam blank 30 has about the same inclination as the corresponding web part in the roll gap contour C01A. As mentioned above, the roll gap height shown for the roll gap contour C01A, corresponds to the height of this roll gap during the last pass of the beam blank 30 through this roll gap contour C01A. To achieve the desired thickness reduction and deformation, three passes through the roll gap contour C01A are e.g. required, wherein the height of the roll gap is progressively decreased. At the outlet of the roll gap contour C01A, the cross-section of the sheet pile blank C0A1 still has a bone-like shape, coming close to the cross-section of the beam blank 30.
In the roll gap contour C01B, the initial shape of a slab 36 is shown. It will be noted that the horizontal plane of symmetry 38 of this slab 36 contains the so called neutral or pass line, i.e. a horizontal line located at half the vertical distance between central axis of the upper roll 26 and the central axis of the lower roll 28. To achieve the desired thickness reduction and initial deformation of the slab 36, only two to four passes through the roll gap contour C01B are required, wherein the height of the roll gap contour C01B is successively decreased. It will be noted in this context that the height (or thickness) of the slab 36, before entering for the first time into the gap contour C01B, is slightly smaller than the height of the fictive rectangle encasing the roll gap contour C01B. (As explained herein below, the height of this rectangle corresponds to [E(CC)−(Dmin(UR)+Dmin(LR))/2], wherein: E(CC) is the vertical distance between the centre lines of the upper roll 26 and the lower roll 28; Dmin(UR) is the minimum diameter of the upper roll 26; and Dmin(LR) is the minimum diameter of the lower roll 28). At the outlet of the roll gap contour C01B, the cross-section of the sheet pile blank C0B1 already has roughly the form of a tilted letter “Z”.
It will be appreciated that, while the contours of the roll gaps C01A and C01B are still quite dissimilar, the contours of the subsequent roll gaps C02A and C02B are already quite similar. It follows that the cross-sections of the sheet pile blanks C02A and C02B, are already similar enough to have a common design for the next roll gap contour C03.
It will be noted that a preform of a specific part of a finished sheet pile 10 (see
In the roll gap contours C02A and C02B (and already in C01B too), a rough preform of the web 16 (see reference 1602), of the first flange 12 (see reference 1202), of the second flange 14 (see reference 1402), of the first corner 18 (see reference 1802) and of the second corner 20 (see reference 2002) are rolled. The rough preform 1802 of the first corner 18 and an adjoining first part 4002 of the rough preform 1602 of the web 16 are formed in a first groove 4202 of the upper roll 26, in which this upper roll 26 has its minimum diameter. The rough preform 2002 of the second corner 20 and an adjoining second part 4402 of the rough preform 1602 of the web 16 are formed in a first groove 4602 of the lower roll 28, in which this lower roll 28 has its minimum diameter. A third part 4802 of the rough preform 1602 of the web 16, which is centrally located between the aforementioned first part 4002 and second part 4402, is formed between two cylindrical (see C02B) or two slightly conical surfaces (see C01B and C02A) of the rolls 26, 28.
In the roll gap contour C03, the thickness of all the aforementioned rough preforms 1202, 1402, 1602, 1802 and 2002 is further reduced. The aforementioned third part 4802 of the rough preform 1602 of the web 16 is widened and now rolled between two cylindrical surfaces of the rolls 26, 28 near the neutral rolling plane 50, i.e. a horizontal plane located at half the vertical distance between central axis of the upper roll 26 and the central axis of the lower roll 28. It follows that the third part 4803 of the rough preform 1603 of the web 16 of the sheet pile blank C03 is substantially flat. Furthermore, a rough preform 2203 of the hook-shaped coupling means 22 is rolled into the end part of the early preform 1202 of the first flange 12, and a rough preform 2403 of the claw-shaped coupling means 24 is rolled into the end part of the rough preform 1402 of the second flange 12.
In the roll gap contour C04, the thickness of all the preforms 1203, 1403, 1603, 1803 and 2003 rolled with the roll gap contour C03 is further reduced. Furthermore, the substantially flat and horizontal third part 4803 of the early preform 1603 of the web 16 is now rolled as a slightly undulated third part 4804, which has—in a cross-section—substantially the form of a letter “S” tilted by 90°. This undulated third or central part 4804 of the preform 1604 of the web 16 is formed partly in a second groove 5204 of the lower roll 28, which is horizontally adjacent to the first groove 4204 in the upper roll 26, and partly in a second groove 5404 of the upper roll 26, which is horizontally adjacent to the second groove 5204 in the lower roll 28. The rough preform 2203 of the hook-shaped coupling means 22 is further elaborated in a third groove 5604 in the lower roll 28, located slightly below the rolling plane 50, by means of a first ring-shaped bead 5804 of the upper roll 26. The rough preform 2403 of the claw-shaped coupling means 24 is further elaborated in a third groove 6004 in the upper roll 26, located slightly above the rolling plane 50, wherein the upper roll 26 has a second ring-shaped bead 6204 located in the third groove 6004 for shaping an internal chamber in the preform 2404 of the claw-shaped coupling means 24.
In the roll gap contours C05 to C07, which are not shown in
The roll gap contour C09 differs from the roll gap contour C08 mainly in the third groove 5609 in the lower roll 28, in which the hook-shaped coupling means 22 is finished, and in the in the third groove 6009 in the upper roll 26, in which the claw-shaped coupling means 24 is finished. The first and second groove 4609, 5209 in the lower roll 28, and the first and second groove 4209, 5409 in the upper roll 26 are substantially equal in the roll gap contours C08 and C09. The sheet pile blank C09 has a curved preform 1609 of the web 16, a curved preform 1209 of the first flange 12, equipped with the hook-shaped coupling means 22, and a curved preform 1409 of the second flange 14, equipped with the claw-shaped coupling means 24. The geometry of the roll gap contour C09 and the sheet pile blank C09 will be described in greater detail hereinafter with reference to
The roll gap contour C10 is conceived as a pure straightening roll gap, in which the curved preform 1609 of the web 16, the curved preform 1209 of the first flange 12, and the curved preform 1409 of the second flange 14 are straightened, thereby conferring the final geometry of a Z-section sheet pile 10, as shown in
Referring now to
Looking at
From the left to the right, the succession of the six grooves forming the roll gap contour C09 is as follows: (1) the third groove 5609 in the lower roll 28; (2) the first groove 4209 in the upper roll 26; (3) the second groove 5209 in the lower roll 28; (4) the second groove 5409 in the upper roll 26; (5) the first groove 4609 in the lower roll 28; and (6) the third groove 6009 in the upper roll 26.
It will further be noted that: Dmin(LRG1) is about equal to Dmin(URG1); Dmin(LRG2) is bigger than Dmin(LRG1); and Dmin(LRG3) is about equal to Dmin(LRG1). Similarly: Dmin(URG2) is bigger than Dmin(URG1); and Dmin(URG3) is about equal to Dmin(URG1).
This layout of the proposed roll gap contour is further illustrated by reference to a rectangle 74, which is drawn in
h=Emin(CC)−[Dmin(URG1)−Dmin(LRG1)]/2.
wherein Emin(CC) is the minimal vertical distance between the centre lines of the upper roll 26 and the lower roll 28, i.e. when the upper roll 26 and the lower roll 28 are closest (in case the sheet pile blank passes several times through the roll gap contour and the height of the roll gap contour is reduced between the successive passes). The neutral rolling plane 50 is the centre plane of the rectangle 74.
The shape of this rectangle 74 may be characterized by its width-to-height-ratio w/h. In the example shown in
It will be appreciated that—due the use of a roll gap contour with a total of six adjacent grooves 5609, 4209, 5209, 5409, 4609, 6009—the individual parts of the sheet pile blank C09 (as well as those of any one of the sheet pile blanks C04 to C08) can be rolled in the direct vicinity of the neutral rolling plane 50, i.e. without requiring deep grooves in the rolls 26, 28. It follows that the initial minimum diameter of the rolls 26, 28 can be bigger; i.e. the roll gap contour can be reworked more often, before the minimum diameters of the rolls decrease beyond a limit value. When compared to the method disclosed in U.S. Pat. No. 5,671,630, the method proposed herein allows gaining about 80 mm on the minimum diameter of the rolls. Furthermore, less deep grooves in the rolls also result in smaller rolling torques and in more equal surface speeds along the roll gap contour, i.e. in less mechanical wear of the surfaces of the rolls. Finally, grooves with generously rounded corners, as in the proposed roll gap contours, also result in smaller stresses in the rolls. In summary, with the proposed method, the rolls wear out less faster and must be reworked less often, but—due to a bigger minimum diameter—can even be reworked more often than with any prior art method for rolling Z-section sheet piles. Consequently, with the proposed method, total life-time of the rolls is substantially increased.
It will further be appreciated that—due to the six adjacent grooves 56, 42, 52, 54, 46, 60—the sheet pile blank is very well guided between the rolls, which facilitates, amongst others, rolling of the coupling means (the sheet pile blank is less likely to deviate laterally).
Another significant advantage of the proposed method is that it is possible to roll the Z-section sheet pile starting with a relatively thin slab.
To facilitate straightening of the curved preform 1609 of the web 16, the depth of the second groove 5209 in the lower roll 28 and the depth of the second groove 5409 in the upper roll 26 are preferably less important the depth of the first groove 4609 in the lower roll 28 and the depth of the first groove 4209 in the upper roll 26. In the example illustrated by the drawings one has e.g.:
[Dnom−Dmin(URG2)]<0.2·[Dnom−Dmin(URG1)]
and
[Dnom−Dmin(LRG2)]<0.2·[Dnom−Dmin(LRG1)].
As can be seen in
In the first groove 4609 of the upper roll 26, the outer flank surface is formed by a conical surface defining an angle α1 of about 67°, and the inner flank surface is formed by a conical surface defining an angle α2 of about 55°, with a cylindrical reference surface centred on the centre line 70 of the upper roll 26. Similarly, in the first groove 4609 of the lower roll 28, the outer flank surface is formed by a conical surface defining an angle α1 of about 67°, and the inner flank surface is formed by a conical surface defining an angle α2 of about 55°, with a cylindrical reference surface centred on the centre line 72 of the lower roll 26. Typically, α1 is in the range of 55° to 75°, preferably 60° to 70°, and α2 is in the range of 45° to 65°, preferably 50° to 60°.
The third part 4809 of the curved preform 1609 of the web 16 has substantially the form of a letter “S” tilted by 90°, forming a wave trough and a wave crest. The central part of the “S”-shaped part, which joins the wave trough to the wave crest, makes an angle β of about 25° (typically β is in the range of 10° to 40°, preferably 20° to 30°).
The preform 1209 of the first flange 12 has substantially the form of a letter “J” that is slightly tilted to the right, wherein the equivalent of the lower branch of the letter “J”, which is equipped with the preform 2209 of the hook-shaped coupling means 22, extends substantially parallel to the neutral plane 50. The preform 1409 of the second flange 14 has substantially the form of a letter “J” that is rotated clockwise by about 180°, wherein the equivalent of the lower branch of the letter “J”, which is equipped with the preform 2409 of the claw-shaped coupling means 24, extends substantially parallel to the neutral plane 50. As already stated above, the preform 2209 of the hook-shaped coupling means 22 is rolled below the neutral rolling plane 50, wherein Dmin(LRG3) is substantially equal to Dmin(LRG1); and the preform 2409 of the claw-shaped coupling means 24 is rolled above the neutral rolling plane 50, wherein Dmin(URG3) is substantially equal to Dmin(URG1). It will also be noted that the preform 2209 has already the final shape of the hook-shaped coupling means 22, and the preform 2409 has already the final shape of the claw-shaped coupling means 24. However, due to the curved preform 1209 and 1409 of the flanges 12 and 14, the orientation of the coupling means 22, 24 is not yet final.
Another embodiment of a roll gap and a sheet pile blank in accordance with the present invention is shown in
The straightening of the sheet pile blank C09 is now described with reference to
The lower straightening roll 28′ includes (see
The upper straightening roll 26′ includes: a first conical section 92, which in
It will consequently be noted that the geometry of the upper straightening roll 26′ and the lower straightening roll 28′ is mainly determined by the geometry of the final Z-section sheet pile 10.
Before the sheet pile blank C09 is introduced between the upper straightening roll 26′ and the lower straightening roll 28′, it is rotated about a longitudinal axis so that the substantially flat first parts 6409 and 6609 of the undulated preform 1609 of the web 16 are substantially parallel to a cone generator of the second conical section 94 of the upper straightening roll 26′, respectively to a cone generator of the second conical section 88 of the lower straightening roll 28′. In the present case the sheet pile blank has e.g. been rotated by an angle of about 12° about a longitudinal axis passing through the convex corner defined by the J-shaped preform 1209 of the first flange 12.
In
The straightening of the sheet pile blank C10 in the roll gap contour C10 may be performed in just one pass. During the straightening, the convex corner portion of the curved preform 1209 of the first flange 12 is guided along the conical section 86 of the lower straightening roll 28′ towards the groove 84 receiving the first coupling means 2209. Similarly, the convex corner portion of the curved preform 1409 of the second flange 14 is guided along the third conical section 96 of the upper straightening roll 26′ towards the groove 98 receiving the second coupling means 2409. Simultaneously, the opening angles α′ of the preforms 1809, 2009 of the first and second corners 18, 20, which are initially greater than 90° but still smaller than the corresponding opening angles in the Z-section sheet pile, increase. The substantially flat first part 6409 of the undulated preform 1609 of the web 16 is guided along the second conical section 94 of the upper straightening roll 26′ towards the conical section 92 of the upper straightening roll 26′. Similarly, the substantially flat second part 6609 of the undulated preform 1609 of the web 16 is guided along the second conical section 88 of the lower straightening roll 88 towards the third conical section of lower upper straightening roll 28′.
During the straightening of the preform 1609 of the web 16, the distance between the points A and B, which are the centres of the corners 18, 20, increases by about 14%. Similarly, the distance between the points C and D on the external end faces of the coupling means increases by about 12%. Finally, the ratio between the overall horizontal width w of the roll gap contours C10 and C09 is about 1.2.
It will be appreciated that the proposed method is particularly advantageous for rolling Z-section sheet piles in which the thickness t2 of the web 16 is smaller than the thickness t1 of the flanges 12, 14 and/or in which the corners 18, 20 are externally and/or internally reinforced by a local extra-thickness of the web 16 and/or the flange 12, 14.
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| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2012/000658 | 4/2/2012 | WO | 00 | 10/1/2014 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2013/150324 | 10/10/2013 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4291564 | Muckli | Sep 1981 | A |
| 5671630 | Grober | Sep 1997 | A |
| 6293133 | Svejkovsky et al. | Sep 2001 | B1 |
| Number | Date | Country |
|---|---|---|
| 121718 | Aug 1976 | DE |
| 2529405 | Aug 1976 | DE |
| 0 284 827 | Oct 1988 | EP |
| 0 890 395 | Jan 1999 | EP |
| 2018656 | Oct 1979 | GB |
| H04288903 | Oct 1992 | JP |
| H07124602 | May 1995 | JP |
| 2004-288903 | Oct 2004 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20150052961 A1 | Feb 2015 | US |
