GB2068799A

GB2068799A - Device and method for forming the rings of cylindrcial storage tanks

Info

Publication number: GB2068799A
Application number: GB8040284A
Authority: GB
Original assignee: Nippon Kokan Ltd
Current assignee: JFE Engineering Corp
Priority date: 1979-12-25
Filing date: 1980-12-16
Publication date: 1981-08-19
Also published as: PH21207A; GB2068799B; JPS5691939A; JPS6236774B2

Abstract

With a device and method for forming the rings of cylindrical storage tanks, a coiled steel plate (11) is paid off, the paid-off portion of the steel plate (11) is bent by a vertical bender (13) with a prescribed curvature to form a curved portion (14), the curved portion (14) starting with its leading end is wound about the vertical cylindrical guiding member (16) which has a prescribed outer diameter and whose centre of rotation is defined by three or more vertical rolls (17), the paying-off operation is stopped when the curved portion (14) is wound about the guiding member (16) to a prescribed length, the curved portion (14) is cut off, and its facing edges are welded together. <IMAGE>

Description

SPECIFICATION Device and method for forming the rings of cylindrical storage tanks This invention relates to a device and method for forming the rings of silos or any other cylindrical storage tanks intended to hold, for example, cereals.

Hitherto, a large cylindrical storage tank whose diameter ranges between several meters and ten and odd meters has been constructed by assembling rings at the side where the storage tank is to be built. The conventional tank ring-forming process has been carried out as follows. As shown in Fig. 1, a steel plate 1 rolled around a pay-off reel 2 mounted on a base is slowly paid-off. The paid-off portion of the steel plate 1 is bent by a bender 3 into a curved steel plate portion 4 having a prescribed curvature. A rope 6 fitted to the leading end 4a of the curved steel plate portion 4 is pulled by a hauling device 7 to pass the curved steel plate portion 4 along the circumference of a tank ring-guiding member 5. Where the leading end 4a of the curved steel plate portion 4 makes a turn along the tank ring-guiding member 5, the curved steel plate portion 4 is cut off.The leading end 4a and cut-off end of the curved steel plate portion 4 are welded together to form a tank ring.

With the known tank ring-forming device and method, the tank ring-guiding member 5 is immovably set. Therefore, as the curved steel plate portion 4 progressively passes along the circumference of the tank ringguiding member 5, a friction between both members increases. Consequently, a tension initially applied to the curved steel plate portion 4 at the outlet of the bender 3 gradually decreases, causing the curved steel plate portion 4 to be curved with an ununiform curvature, and possibly leading to the formation of a distorted tank ring. Moreover, the proximity of the leading end 4a of the curved steel plate 4 fitted with the hauling rope 6 tends to be pulled away from the tank ring-guiding member 5 when the winding of the curved steel plate 4 is brought to an end.Accordingly, the terminal portion of the wound steel plate portion 4 fails to be bent with a prescribed curvature, making it necessary to reshape the formed tank ring in order to let it have a uniform curvature. Further drawback accompanying the conventional tank ring-forming device is that since the curved steel plate portion 4 slides along the tank ring-guiding member 5, the inner wall of the curved steel plate portion 4 is scarred, because it is rubbed by the outer wall of the tank ring-guiding member 5.

It is accordingly the object of this invention to provide a tank ring-forming device and method. wherein a steel plate portion bent with a prescribed curvature by a bender is wound about the outer peripheral wall of a rotatable vertical cylindrical guiding member which has a prescribed outer diameter and whose centre of rotation is defind by three or more vertical rolls, thereby forming tank rings for a cylindrical storage tank, each of which has a uniform curvature throughout the circumference and is free of scars.

According to one aspect of this invention, there is provided a device for forming the rings of cylindrical storage tanks, which com- prises a horizontal base, horizontal rolls rotatably mounted on the base, a vertical cylindrical guiding member rotatably supported on the horizontal rolls, at least three vertical rolls rotatably set on the base around the vertical cylindrical guiding member, a pay-off reel on which a coiled steel plate is set and which is rotated in the same direction as that in which the coiled steel plate is to be paid off, and a vertical bender which is disposed between the vertical cylindrical guiding member and payoff reel to bend the paid-off portion of the steel plate with a prescribed curvature.

According to a further aspect of the invention, there is provided a method for forming the rings of cylindrical storage tanks, which comprises the steps of paying off a coiled steel plate, bending the paid-off portion of the steel plate by a vertical bender with a prescribed curvature, winding the paid-off curved portion of the steel plate about a rotatable vertical cylindrical guiding member which has a prescribed outer diameter and whose centre of rotation is defined by three or more vertical rolls with the guiding member rotated, stopping the paying-off of the steel plate when it is wound about the vertical cylindrical guiding member in a prescribed length, cutting off the wound portion of the steel plate in said prescribed length, removing the cut-off portion of the steel plate from the vertical cylindrical guiding member, and welding together the mutually facing edges of the cut-off portion of the steel plate, thereby forming a tank ring.

This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Figure 1 is an oblique view showing the conventional device and method for forming the rings of cylindrical storage tanks; Figure 2 is a plan view of a device and method according to one embodiment of this invention for forming the tank rings of a cylindrical storage tank; Figure 3 is a partial oblique view of the main part of a device according to another embodiment of the invention for forming the rings of a cylindrical storage tank; Figure 4 is a partial oblique view of the main part of a device according to still another embodiment of the invention for forming the rings of a cylindrical storage tank; Figure 5 is a plan view showing the condition in which a coiled steel plate is drawn out to a bender, using a dummy steel plate;; and Figure 6 is a plan view illustrating the condition in which the drawn out portion of the coiled steel plate is taken up on the vertical cylindrical guiding member with the dummy steel plate welded to the leading end of the drawn out portion of the coiled steel plate.

Referring to Fig. 2, a vertical pay-off reel 12 rotated by an electric motor or a hydraulic motor is mounted on a base 10 horizontally set near the site at which a cylindrical storage tank is to be built. A coiled steel plate 11 is mounted on the reel 12. The pay-off reel 12 is rotated in the same direction as that in which the coiled steel plate 11 is to be drawn out. That portion 14 of the steel plate 1 1 which is paid off by the rotation of the pay-off reel 12 is delivered to a bender 13. The bender is of a vertical roll type. Horizontal rollers 15 are arranged at a proper interval in the circumferential direction of a circle having a prescribed radius, and rotatably supported on the base 10.The horizontal rolls 15 bear the weight of the curved portion 14 of the steel plate 11 which is paid off the bender 13, carry the curved portion 14 in the circumferential direction of a vertical cylindrical guiding member 16, and support the guiding member 16 such that the guiding member 16 is rotatable. The vertical cylindrical guiding member 16 has substantially the same outer diameter as the curved portion 14 of the steel plate 11.The centre of rotation of the vertical cylindrical guiding member 16 is defined by, for example, three rotatable vertical rolls 17 mounted on the base 10 equidistantly in the circumferential direction of the guiding member 16. A circle defined by radially facing portions of the peripheral walls of the three vertical rolls 17 has a diameter substantially equal to a sum of the outer diameter of the vertical cylindrical guiding member 16 and twice thickness of the curved portion 14 of the steel plate 11.

In operation, that portion of the steel plate 11 which is drawn out by the rotation of the pay-off reel 12 passes through the bender 13 to be bent with a prescribed curvature. The resultant curved portion 14 is brought to the first horizontal roll 15 and the first vertical roll 17, touches the outer peripheral wall of the vertical cylindrical guiding member 16 while being guided by the first horizontal roller 15, and is taken up on or wound about the vertical cylindrical guiding member 16 while it is rotated by the curved portion 14. The other horizontal rolls 15 and the other vertical rolls 17 guide the curved portion 14 of the steel plate 11 as it is brought thereto, thereby enabling the curved portion 14 to be unfailingly taken up on the vertical cylindrical guiding member 16. Therefore, the curved portion 14 is saved from scars and buckling.

The initial part of the curved portion 14 does not generally have a proper curvature.

Therefore, the curved portion 14 is first wound about the guiding member 1 6 in a length equal to a sum of the length of the initial improperly bent part and the circumferential length of a regular tank ring. Thereafter, the initial improperly bent part of the curved portion 14 and that part consecutive thereto which has the prescribed circumferential length of a regular tank ring are thermally cut off. The leading parts of the second and succeeding tank rings are alrady formed with a prescribed curvature. Therefore, these tank rings have only to be thermally out off at the respective leading edges in a prescribed tank ring length.Each time the bent portion 14 is thermally cut-off, the cut-off part is lifted from the vertical cylindrical guiding member 16 by a crane to be placed in a different site, where the mutually facing edges of the thermally cut-off part of the curved portion 14 are welded together to form a tank ring.

Description is now given with reference to Fig. 3 of a tank ring-forming device according to another embodiment of this invention. A flange 1 6a is formed along the lower end of the vertical cylindrical guiding member 16.

The flange 1 6a renders the guiding member 16 more rigid, prevents its deformation, and supports the lower end of the curved portion 14 of the steel plate 1 1, thereby ensuring the paying-off of the curved portion 14 on the vertical cylindrical guiding member 16.

A disc flange 1 7a is fixed to the lower part of the shaft of each of the vertical rolls 1 7 to support the flange 1 6 a. The outer edge of the flange 1 6a is positioned between the underside of the vertical roll 17 and the upper side of the disc flange 1 7a. Where, therefore, the curved portion 14 of the steel plate 11 is pulled up from the vertical cylindrical guiding member 16 after wound thereabout, the outer edge of the flange 1 6a abuts against the underside of the vertical roll 17, thereby preventing the vertical cylindrical guiding member 16 from being lifted with the pull-up curved portion 14. Further, a combination of the vertical rolls 17 and flanges 1 7a enable a number of horizontal rolls 15 to be decreased.

Description is now given with reference to Fig. 4 of a tank ring-forming device according to another embodiment of this invention. With the embodiment of Fig. 4, the inner edge of the flange 1 6a formed on the lower end of the vertical cylindrical guiding member 1 6 is clamped between one or more pairs of horizontal pinch rollers 18 (only one pair is indicated). The rotation of the pinch rollers 18 causes the vertical cylindrical guiding member 16 to be rotated at substantially the same circumferential speed and in the same direction as when the curved portion 14 of the steel plate 11 is paid off. Fixed to gears 19 meshing each other are the pinch rollers 18 by shafts 1 8a rotatably supported on the base 10.The pinch rollers 18 are rotated at the same speed and in the same direction of the paid-off steel plate by driving means such as an electric motor or a hydraulic motor through the gears 19, a rotation-transmitting unit such as gear trains (not shown) coupled to the gears 19 and the driving means.

Description is now given with reference to Figs. 5 and 6 of a tank ring-forming device according to still another embodiment of this invention. With this embodiment, a dummy steel plate 20 is previously welded to the leading end of the bent portion 14 of the coiled steel plate 11 set on the pay-off reel 12 with substantially the same thickness as the steel plate 11.

With the above-mentioned embodiment, a dummy steel plate 20 is bent by a bender 13 as seen from Fig. 5. That portion of the steel plate 11 which immediately follows the dummy steep plate 20 is drawn out from the pay-off reel 12 while being bent (this curved portion is indicated by reference numeral 14 in Fig. 6). When a welded seam between the dummy steel plate 20 and the leading end of the bent portion 14 of the steel plate 11 reaches the outer periphery of the vertical cylindrical guiding member 16 as shown in Fig. 6, the dummy steel plate 20 is cut off from the leading end of the curved portion 14.An improper curvature occurring when the steel plate 11 is initially drawn out (or paid off) from the bender 13 is absorbed in the dummy plate 20, offering the advantage that since the paid-off steel plate 11 is bent by the bender 13 to form a curved portion 14 with a prescribed curvature from the start, loss of material (that is, the steel plate 11) can be eliminated. After the formation of a first tank ring, the succeeding tank ring can be fabricated without the welding of the dummy steel plate 20 simply by repeating the regular operation cycle.

This invention is intended for the formation of the rings of a cylindrical storage tank used mainly to hold cereals. This invention proves particularly effective where a tank ring has a diameter ranging between several meters and ten and odd meters and a thickness ranging between 5 millimeters and 10 and odd millimeters.

According to the above-mentiond device and method of this invention for forming the rings of cylindrical storage tanks, a paid-off portion of a steel plate previously coiled is bent by a bender with a prescribed curvature and thereafter wound about a vertical rotatable cylindrical guiding member to form a tank ring. Therefore, the invention offers the advantage of efficiently forming tank rings, each of which has a uniform curvature throughout the circumference, that is, a high degree of roundness.

Claims

1. A device for forming the rings of cylindrical storage tanks which comprises: a horizontal base; horizontal rolls rotatably mounted on the base; a vertical cylindrical guiding member rotatably mounted on the horizontal rolls; at least three vertical rolls rotatably arranged on the base around the vertical cylindrical guiding member to define the centre of rotation of said guiding member; a pay-off reel on which a coiled steel plate is set and which is rotated in the same direction as that in which the coiled steel plate is to be paid off; and a vertical bender disposed between the vertical cylindrical guiding member and pay-off reel to bend the paid-off portion of the steel plate with a prescribed curvature.

2. The device according to claim 1, which further comprises drive means for rotating the vertical cylindrical guiding member in the same direction and at substantially the same circumferential speed as when the steel plate is to be paid off.

3. The device according to claim 1 or 2, wherein a flange is formed on the lower end of the vertical cylindrical guiding member, and a disc flange is provided on the shaft of each of the vertical rolls so as to support the flange of the cylindrical guiding member.

4. The device according to claim 3, wherein said drive means includes at least one pair of pinch rollers which are rotated in the opposite directions to each other and between which the inner edge of the flange of the vertical cylindrical guiding member is clamped.

5. A method for forming the rings of cylindrical storage tanks which comprises the steps of: paying off a coiled steel plate; bending the paid-off portion of the steel plate by a vertical bender with a prescribed curvature; winding the paid-off curved portion of the steel plate about the vertical cylindrical guiding member which has a prescribed diameter and whose centre of rotation is defined by at least three vertical rolls with the guiding member rotated; stopping the paying-off of the steel plate when it is wound about the vertical cylindrical guiding member in a prescribed length; cutting off the wound portion of the steep plate in said prescribed length; removing the cut-off portion of the steel plate from the vertical cylindrical guiding member; and welding together the mutually facing edges of the cut-off portion to form a tank ring.

6. The method according to claim 5, which comprises the step of rotating the verti cal cylindrical guiding member in the same direction and at substantially the same circumferential speed as when the steel plate is to be paid off.

7. The method according to claim 6, which comprises the steps of: providing a disc flange below the vertical roll concentrically therewith; providing another flange whose inner edge is disposed between the vertical roll and disc flange to support the vertical cylindrical guiding member, such that the inner edge of the flange of the guiding member abuts against the underside of the vertical roll when the curved portion is pulled up from the guiding member, thereby preventing the guiding member from being lifted together with the curved portion of the steel plate paid off on the guiding member.

8. The method according to claim 7, wherein said vertical cylindrical guiding member is rotated by at least one pair of pinch rollers clamping the inner edge of the flange formed on the lower end of said guiding member.

9. The method according to any one of claims 5 to 8, which comprises the step of previously welding a dummy steel plate to the leading end of the steel plate.

10. The device and method for forming the rings of cylindrical storage tanks, substangially as hereinbefore described with reference to Figs. 2 to 6.