Method for manufacturing helical spiral stair for vertical cylindrical storage tank

Abstract

The application provides a vertical cylindrical storage tank spiral ladder manufacturing method, which comprises the following steps: firstly, determining the chord length of the plane projection circle of the spiral line of the inner side plate of the spiral ladder; secondally, equally dividing the chord length to determine the size corresponding to the intersection point of the vertical line of each equal division point of the chord length and the plane projection circle arc of the inner side plate of the spiral ladder; manufacturing a butt welding jig for the spiral ladder set; firstly, fixing the inner side plate of the spiral ladder on the jig; then, according to the spiral ladder construction drawing, welding and fixing one end point of the step plate to the inner side plate of the spiral ladder, and naturally forming the spiral line of the outer side plate at the other end of the step plate; then, gradually welding and fixing the outer side plate of the spiral ladder and the step plate point by point; after the step plate and the side plate are completely welded and fixed on the ladder jig, the welding of the spiral ladder is completed, and then the spiral ladder is manufactured after cooling, and the integral lifting condition is achieved. The application can effectively reduce the risk of high-altitude operation, greatly improve the manufacturing precision, and improve the labor efficiency.

Description

Technical Field

[0001] This invention relates to the field of non-standard equipment manufacturing technology for petrochemical projects, and in particular to a method for manufacturing a spiral staircase for a vertical cylindrical steel welded storage tank. Background Technology

[0002] Vertical cylindrical welded steel storage tanks are widely used in petrochemical projects, and spiral staircases, used for operation and maintenance, are an essential auxiliary structure for these tanks.

[0003] Regarding the common manufacturing methods for spiral staircases of vertical cylindrical welded storage tanks, one method is to weld the spiral staircase together with the storage tank in sections as each tank plate is inverted and lifted; the other method is to hoist the prefabricated spiral staircase as a whole after the tank wall plates are installed upright.

[0004] Regarding the overall hoisting method, patent document CN201210316246 discloses a method for manufacturing a spiral staircase, including the following steps: 1) making inner and outer rolling arc templates; 2) making inner and outer stair beams; 3) making two right-angled triangles, one large and one small, and then assembling and splicing the inner and outer stair beams and steps using the triangles; through the above steps, the spiral staircase is manufactured. However, this method of manufacturing spiral staircases is difficult to control and has low construction efficiency. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for manufacturing a spiral ladder for a vertical cylindrical storage tank, so as to reduce the risk of working at height, greatly improve the manufacturing accuracy, and improve labor efficiency.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a method for manufacturing a spiral staircase for a vertical cylindrical storage tank, comprising the following steps:

[0007] Step 1: First, determine the chord length of the planar projection circle of the spiral line of the inner side plate of the spiral staircase; on the chord length connecting the start and end points of the spiral line of the inner side plate of the spiral staircase, divide the chord length into several equal parts, and determine the dimensions corresponding to the intersection of the perpendicular line of each division point of the chord length and the arc of the planar projection circle of the inner side plate of the spiral staircase.

[0008] Step 2: Fabricate a spiral staircase jig, which includes a jig base, a jig upright plate, and a jig top steel strip;

[0009] Draw a center line along the length of the base of the jig. Based on the chord length of the inner plate of the spiral staircase obtained in step one, mark the start and end points of the chord length on the base of the jig. Calculate the length of each division based on the number of equal divisions of the chord length in step one, and mark the division points on the base of the jig.

[0010] A mold vertical plate corresponding to each of the points is made, and the height of each of the mold vertical plates is calculated as the dimension corresponding to the intersection of the vertical line of each of the points and the projected arc of the inner side plate of the spiral ladder, and the width B of each of the mold vertical plates is A / sinβ, wherein A is the width of the inner and outer side plates of the spiral ladder, and β is the rise angle of the spiral ladder; the mold vertical plate is fixed to the surface of the mold base corresponding to the points, and the angle between the mold vertical plate and the length direction of the mold base is the rise angle β of the spiral ladder;

[0011] The top steel band of the mold is fixed to the top of the mold vertical plate;

[0012] In step three, the inner side plate of the spiral ladder with the divided lines of the steps of the spiral ladder is fixed to the top steel band of the mold of the spiral ladder;

[0013] In step four, one end of each of the step plates of the spiral ladder is fixed to the inner side plate of the spiral ladder according to the divided lines of the steps of the spiral ladder;

[0014] In step five, the outer side plate of the spiral ladder with the divided lines of the steps of the spiral ladder is fixed to the mold of the spiral ladder with the other end of the step plate, and the assembly of the spiral ladder is completed.

[0015] Further, in step two, the mold base is made of H-shaped steel or box-shaped square tube.

[0016] Further, the mold vertical plate is made of Q235 steel plate with a thickness of 6 mm.

[0017] Further, in step two, the height of each of the mold vertical plates is 200 mm higher than the calculated value.

[0018] Further, in step three, the inner side plate of the spiral ladder and the top steel band of the mold are fixed by the clamps arranged at intervals, and the clamps are provided with clamping grooves for clamping the inner side plate of the spiral ladder and the top steel band of the mold.

[0019] The spiral ladder manufacturing method of the vertical cylindrical steel storage tank provided by the application is relatively simple in terms of the calculation and application of trigonometric functions and Pythagorean theorem in the manufacture of the mold. The thickness of the side plate of the spiral ladder is generally less than 6 mm, and the side plate itself has good flexibility. The side plate does not need to be rolled and curved according to the application. The spiral ladder is fixed by spot welding on the mold, and then welded. The plastic deformation principle of steel is fully utilized, the welding deformation is small, the manufacturing precision is high, the ground assembly and welding construction is basically free of high-altitude operation, the operation efficiency is improved, and the safety risk is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a schematic view of the vertical surface of the storage tank and the spiral ladder;

[0021] Figure 2 Elevation view of the spiral ladder of the present application is made;

[0022] Figure 3 Top view of the spiral ladder of the present application is made;

[0023] Figure 4 A-A section view of the spiral ladder of the present application is made;

[0024] Figure 5 Horizontal projection view of the storage tank and the spiral ladder; α is the included angle of the spiral ladder plane projection; R is the inner diameter of the storage tank; R1 is the inner circle radius of the spiral ladder plane projection; R2 is the outer circle radius of the spiral ladder plane projection;

[0025] Figure 6 Calculation view of the spiral ladder is made; O is the center of the storage tank plane projection; R1 is the inner circle radius of the spiral ladder plane projection; L is the chord length corresponding to the arc of the spiral ladder plane projection; h1 is the vertical distance between the mid-point position of the spiral ladder plane projection and the intersection point between the center point of the inner circle of the spiral ladder plane projection and the center point of the chord of the spiral ladder; hn is the vertical distance between the n-th equal division point on the chord of the spiral ladder and the intersection point between the inner circle of the spiral ladder plane projection.

[0026] In the figure, 1 is the storage tank; 2 is the spiral ladder; 3 is the jig base; 4 is the jig vertical plate; 5 is the jig top steel belt; 6 is the inner side plate of the spiral ladder; 7 is the step plate; 8 is the outer side plate of the spiral ladder; 9 is the clamp. DETAILED DESCRIPTION

[0027] A typical embodiment of the present application provides a method for manufacturing a vertical cylindrical welded storage tank spiral ladder, mainly including theoretical calculation, spiral ladder jig manufacturing and spiral ladder assembly and welding. The storage tank and the spiral ladder involved in the present application are as shown in the figure, and the overall concept of the manufacturing method is to first fix the inner side plate 6 of the spiral ladder on the spiral jig, then according to the spiral ladder construction drawing, to point weld and fix one end of the step plate 7 to the inner side plate 6 of the spiral ladder, to naturally form the spiral line of the outer side plate 8 of the spiral ladder at the other end of the step plate 7, and then to point weld and fix the outer side plate 8 of the spiral ladder and the step plate 7. After the step plate and the side plate are completely point welded and fixed, the welding of the spiral ladder on the spiral ladder jig is completed, and then the spiral ladder is completed after cooling, and the overall hoisting condition is met. Figure 1

[0028] Theoretical calculations

[0029] ​By calculation, firstly, the chord length of the plane projection circle of the helical line of the helical ladder inner side plate 6 is determined; on the chord length connecting the starting point and the ending point of the helical line of the helical ladder inner side plate 6, the chord length is equally divided into several parts, and the corresponding size of the intersection point of the vertical line of each equally divided point of the chord length and the plane projection circle arc of the helical ladder inner side plate 6 is determined.

[0030] Manufacture of spiral disc ladder tool

[0031] The helical ladder mold comprises a mold base 3, a mold vertical plate 4 and a mold top steel belt 5.

[0032] The helical ladder mold base plate is made of H-shaped steel or box-shaped square tube, and the general length is 12 meters, which is greater than the chord length of the helical line of the helical ladder.

[0033] A center line is drawn along the length direction of the mold base 3, the starting point and the ending point of the chord length are drawn on the mold base 3 according to the chord length of the helical ladder inner side plate obtained in step one, and the length of each equally divided part is calculated according to the equally divided number of the chord length in step one, and the equally divided points are marked on the mold base 3.

[0034] As shown in the helical ladder manufacturing calculation schematic diagram, Figure 6 the chord length corresponding to the starting point and the ending point of the helical ladder is equally divided into n parts in the plane projection view of the helical ladder inner side plate 6, the more the equally divided points are, the more accurate the calculation result is, and considering the manufacturing convenience and the accuracy meeting the construction requirements, the equally divided points are generally taken as 22 equally divided parts. Correspondingly, a center line is drawn along the length direction of the mold base 3, two end points of the chord length of the helical ladder inner side plate 6 are drawn according to the calculation result, the chord length of the helical ladder inner side plate 6 is also equally divided into n parts, and considering the manufacturing convenience and the accuracy meeting the construction requirements, the equally divided number is generally taken as 22, and the number of equally divided points is consistent with the number of equally divided parts of the chord length of the plane projection of the helical ladder inner side plate.

[0035] The helical ladder mold vertical plate 4 is made of Q235 steel plate with a thickness of 6 mm, and each equally divided point on the mold base 3 corresponds to the helical ladder mold vertical plate 4. The number of the helical ladder mold vertical plate 4 is consistent with the number of the equally divided parts on the mold base 3.

[0036] The calculation value of the height of each helical ladder mold vertical plate 4 is the size corresponding to the intersection point of the vertical line of each equally divided point on the chord length of the plane projection circle of the helical ladder inner side plate 6 and the plane projection circle arc of the helical ladder inner side plate 6 determined in step one.

[0037] As shown in the helical ladder manufacturing calculation schematic diagram, Figure 4 the width of each helical ladder mold vertical plate 4 is the same, and the value is calculated by a trigonometric function, the width B of each helical ladder mold vertical plate 4 is A / sinβ, wherein A is the width of the helical ladder inner and outer side plates, and β is the rise angle of the helical ladder; the helical ladder mold vertical plate 4 is fixed on the surface of the mold base 3 corresponding to the equally divided points, and the angle between the helical ladder mold vertical plate 4 and the length direction of the mold base 3 is the rise angle β of the helical ladder.

[0038] The cutting height of each die upright plate 4 is calculated by adding 200mm to allow for welding positions and prefabrication allowance for the inner side plate of the spiral staircase.

[0039] like Figure 2 As shown, the number of equally spaced points marked on the jig base 3 is the same as the number of jig upright plates 4. The jig upright plates 4 are spot-welded to the jig base 3 in the order of equal division. During spot welding, a center line is drawn in the width direction of the jig upright plate 4 for easy positioning.

[0040] When spot welding the jig upright plate 4, use a right-angle ruler to check the verticality of the jig plate. Spot welding should be performed on both sides of the jig upright plate 4 to ensure a stable and reliable fixation. After spot welding, weld the jig upright plate 4 to the jig base 3. After welding, check and adjust any deformation caused during the welding process to ensure the angle and verticality of the jig upright plate 4 after welding. After spot welding is completed, weld the jig upright plate 4 to the jig base 3.

[0041] Make an angle template. The angle between the jig stand plate 4 and the jig base 3 along the length direction is the helix angle β of the spiral staircase 2.

[0042] The direction of the angular spot welding of the jig stand plate 4 is determined by the rotation direction of the spiral ladder 2. That is, the spiral ladder 2 is left-handed (when the operator walks on the spiral ladder 2 to climb onto the storage tank 1, the left hand is close to the tank wall of the storage tank 1, which is left-handed), and the angle of the jig stand plate 4 is higher on the left and lower on the right (when facing the cross section of the jig base 3, and the position is perpendicular to the center line of the length direction of the jig base 3, the left side of the jig stand plate 4 appears higher and the right side lower). According to the above principle, the position line of each jig plate is marked on the jig base 3 using an angle template.

[0043] The top steel strip 5 of the fixture is 6mm thick, with a width consistent with the width of the spiral staircase side plate and a length consistent with the length of the spiral staircase inner side plate.

[0044] like Figure 2 As shown, after the jig upright plate 4 is welded and cooled, the top steel strip 5 of the jig is spot welded to the top of the jig upright plate 4. During spot welding, check the gap between the top steel strip 5 of the jig and each jig upright plate 4 at the contact point. It should be uniform. After spot welding, each jig upright plate 4 is welded to the top steel strip 5 of the jig by segmented welding to complete the fabrication of the spiral ladder jig.

[0045] Butt welding of spiral disc ladder set

[0046] like Figure 2 As shown, the inner side plate 6 of the spiral staircase with the digits of the spiral staircase steps already marked is fixed to the top steel strip 5 of the spiral staircase fixture.

[0047] Specifically, on the inner side plate 6 of the spiral staircase, the position of each step plate is marked according to the construction drawing, and the side with the step division line is fixed to the spiral staircase manufacturing jig.

[0048] As shown in Figure 2 , 3 In the preferred embodiment, the inner side plate 6 of the spiral staircase and the top steel band 5 of the jig are fixed by the spacer clamp 9, and the clamp 9 has a slot on one section for clamping the inner side plate 6 of the spiral staircase and the top steel band 5 of the jig.

[0049] One end of each spiral staircase step plate 7 is spot welded to the inner side plate 6 of the spiral staircase according to the step division line marked on the inner side plate 6 of the spiral staircase, and the other end of the step plate 7 forms a curve at the step end point, which naturally forms the spiral line of the outer side plate of the spiral staircase.

[0050] The outer side plate 8 of the spiral staircase with the spiral staircase step division line is spot welded to the outer side plate 9 of the spiral staircase with the other end of the step plate 7 as the jig, and the assembly and fixation of the spiral staircase are completed.

[0051] Specifically, the positioning line of each step plate is marked on the outer side plate 8 of the spiral staircase according to the drawing, and the side with the positioning line is downwardly spot welded to the step plate 7 one by one.

[0052] After the outer side plate 8 of the spiral staircase and the step plate 7 are firmly spot welded, the overall welding of the spiral staircase 2 is performed, the welding seam between the step plate and the side plate is performed according to the requirements of the drawing, and two welders are arranged to weld in sections in the order from the center to the sides to reduce welding stress concentration. After welding, natural cooling is performed to complete the manufacturing of the spiral staircase.

Claims

1. A method for manufacturing a spiral staircase for a vertical cylindrical storage tank, characterized in that, It comprises the following steps: Step one, firstly determine the chord length of the plane projection circle of the helical line of the inner side plate of the spiral stair; divide the chord length connecting the starting point and the ending point of the helical line of the inner side plate of the spiral stair into several equal parts, and determine the size corresponding to the intersection point of the vertical line of each equal part point and the plane projection circle arc of the inner side plate of the spiral stair; Step two, make a spiral stair mold, which comprises a mold base, a mold stand and a mold top steel belt; Draw a center line along the length direction of the mold base, mark the starting point and the ending point of the chord length of the inner side plate of the spiral stair on the mold base according to the chord length obtained in step one; calculate the length of each equal part according to the equal part number of the chord length in step one, and mark the equal part points on the mold base; Make a mold stand corresponding to each equal part point; the calculation value of the height of each mold stand is the size corresponding to the intersection point of the vertical line of each equal part point on the chord length of the plane projection circle of the inner side plate of the spiral stair and the plane projection circle arc of the inner side plate of the spiral stair determined in step one; the width B of each mold stand is A / sinβ, wherein A is the width of the inner and outer side plates of the spiral stair, and β is the rise angle of the spiral stair; fix the mold stand on the surface of the mold base corresponding to the equal part point, and the angle between the mold stand and the length direction of the mold base is the rise angle β of the spiral stair; Fix the mold top steel belt on the top of the mold stand; Step three, fix the inner side plate of the spiral stair with the equal part line of the spiral stair step drawn on it to the mold top steel belt of the spiral stair mold; Step four, fix one end of each spiral stair step plate to the inner side plate of the spiral stair according to the equal part line of the spiral stair step drawn on the inner side plate of the spiral stair; Step five, fix the outer side plate of the spiral stair with the equal part line of the spiral stair step drawn on it to the spiral stair with the other end of the step plate as the mold, and complete the assembly and fixation of the spiral stair.

2. The method of claim 1, wherein: In step two, the mold base is made of H-shaped steel or box-shaped square tube.

3. The method according to claim 1 or 2, characterized in that: In step two, the mold stand is made of Q235 steel plate with a thickness of 6mm.

4. The method of claim 3, wherein: In step two, the height of each mold stand is 200mm based on the calculation value.

5. The method of claim 4, wherein: In step three, the inner side plate of the spiral stair and the mold top steel belt are fixed by the clamps arranged at intervals, and a clamping groove for clamping the inner side plate of the spiral stair and the mold top steel belt is opened on one section of the clamp.

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