Steel ladder stand and preparation method thereof

Abstract

The invention relates to the technical field of wind power generation, and provides a steel ladder stand and a preparation method thereof.The preparation method comprises the steps that rolling forming equipment is adopted for bending forming of a steel belt, and a cylindrical vertical beam and a cylindrical stepping stick are prepared; punching operation is conducted on the vertical beam, and a plurality of through holes are formed in the vertical beam; the two ends of a stepping stick are arranged in the corresponding penetrating holes of the two vertical beams in a penetrating mode, and at least part of the ends of the stepping stick are exposed out of the outer side faces of the vertical beams; the area, penetrating through the vertical beam, of the treading stick is subjected to tooth expanding operation, the end of the treading stick is subjected to flanging and riveting operation, and the vertical beam and the treading stick are connected into a whole; the steel strip meets the following parameters that the thickness ranges from 0.5 mm to 3 mm, the yield strength ranges from 230 MPa to 420 MPa, the tensile strength ranges from 330 MPa to 560 MPa, and the ductility ranges from 20% to 35%. The manufacturing method is low in machining cost, high in machining efficiency and high in yield, the mechanical strength and corrosion resistance of the manufactured steel ladder stand are guaranteed, and the steel ladder stand can be reliably used in the severe environment.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, and in particular to a steel ladder and its manufacturing method. Background Technology

[0002] Currently, with the rapid development of the wind power industry, the installed capacity of wind turbines continues to grow, and the installation height of wind turbines is getting higher and higher. The concrete tower, as the core structure supporting the wind turbine, has ladders installed on its side walls. These ladders are mainly used for personnel to climb and to guide lifting equipment, facilitating regular inspection and maintenance of the wind turbine.

[0003] Existing concrete towers primarily utilize aluminum alloy ladders, which are easy to machine. However, these ladders are relatively expensive. In practical applications, it has been found that the coefficients of linear expansion of concrete and aluminum alloy differ significantly for the specific application scenarios of concrete towers, resulting in aluminum alloy ladders failing to meet design requirements in terms of mechanical strength. While steel ladders have a coefficient of linear expansion close to that of concrete and higher mechanical strength than aluminum alloy ladders, their superior strength also makes them more difficult and expensive to manufacture. Furthermore, existing steel ladders are typically assembled using welding, which poses a risk of weld failure in harsh conditions such as offshore environments, hindering their application in concrete towers within the wind power industry. Summary of the Invention

[0004] This invention provides a steel ladder and its manufacturing method, which at least solves or improves the problem that ladders currently used in the wind power generation field cannot simultaneously achieve low processing cost, high mechanical strength, high yield, and reliable use in harsh environments.

[0005] In a first aspect, the present invention provides a method for manufacturing a steel ladder, comprising: The steel strip is bent into shape using a roll forming machine to prepare cylindrical vertical beams and treadles respectively; The vertical beam is punched to create a plurality of through holes, which are arranged along the extension direction of the vertical beam. The two ends of the foot rod are inserted into the corresponding holes of the two vertical beams, with at least a portion of the end of the foot rod exposed on the outer side of the vertical beam; The area where the foot rod passes through the vertical beam is subjected to a threading operation, and the end of the foot rod is subjected to a riveting operation to connect the vertical beam and the foot rod into one piece; The steel strip meets the following parameters: thickness of 0.5-3mm, yield strength of 230-420MPa, tensile strength of 330-560MPa, and elongation of 20%-35%.

[0006] According to a method for manufacturing a steel ladder provided by the present invention, the step of using a roll forming machine to bend a steel strip to prepare a cylindrical vertical beam includes: Based on the outline shape of the cross-section of the vertical beam to be formed, determine the width of the first steel strip used to prepare the vertical beam, and then feed the first steel strip. While controlling the first steel strip to be fed at the first speed, the roll forming equipment is controlled to perform multiple roll forming passes along the feeding direction of the first steel strip, gradually bending the first steel strip in the width direction into a cylindrical vertical beam to be welded. Welding is performed on the weld seams of the vertical beam to be welded.

[0007] According to a method for manufacturing a steel ladder provided by the present invention, the step of controlling the roll forming equipment to sequentially perform multiple roll forming passes along the feeding direction of the first steel strip, and gradually bending the first steel strip in its width direction into a cylindrical vertical beam to be welded, includes: A first region of the first steel strip is rolled to create a groove shape on the first steel strip, the groove shape being used to form an inward concave structure on the outer surface of the vertical beam; According to the outline shape of the cross-section of the vertical beam to be formed, along the width direction of the first steel strip, the portion of the first steel strip other than the first area is gradually bent until the two sides of the first steel strip are aligned to obtain the vertical beam to be welded.

[0008] According to a method for manufacturing a steel ladder provided by the present invention, after welding the weld seam on the vertical beam to be welded, the manufacturing method further includes: Once it is confirmed that the dimensions of the vertical beam to be welded meet the requirements, zinc supplementation is performed on the weld bead on the vertical beam to be welded.

[0009] According to a method for manufacturing a steel ladder provided by the present invention, punching a hole in the vertical beam further includes: Multiple fixing holes are constructed on the vertical beam, and at least two of the fixing holes are located on both sides of the multiple through holes along the extension direction of the vertical beam; The fixing hole is used to connect the opposite ends of two adjacent steel ladders.

[0010] According to a method for manufacturing a steel ladder provided by the present invention, the step of bending a steel strip using a roll forming device to prepare cylindrical treads includes: Based on the outline shape of the cross-section of the foot pedal to be formed, determine the width of the second steel strip used to prepare the foot pedal, and then feed the second steel strip. While controlling the second steel strip to be fed at the second speed, the roll forming equipment is controlled to perform multiple roll forming passes along the feeding direction of the second steel strip, gradually bending the second steel strip in its width direction into a cylindrical treadle to be welded; Welding is performed on the weld seam of the footplate to be welded.

[0011] According to a method for manufacturing a steel ladder provided by the present invention, the step of controlling the roll forming equipment to sequentially perform multiple roll forming passes along the feeding direction of the second steel strip, and gradually bending the second steel strip in its width direction into a cylindrical step to be welded, includes: At least one second region of the second steel strip is rolled to create an embossed pattern on the second steel strip, the embossed pattern being used to form an anti-slip surface on the surface of the footplate; According to the outline shape of the cross-section of the foot pedal to be formed, along the width direction of the second steel strip, the portion of the second steel strip other than the second region is gradually bent until the two sides of the second steel strip are aligned to obtain the foot pedal to be welded.

[0012] According to a method for manufacturing a steel ladder provided by the present invention, the weld seam on the step bar to be welded is welded, and the manufacturing method further includes: After confirming that the dimensions of the footplate to be welded meet the requirements, zinc supplementation is performed on the weld bead on the footplate to be welded.

[0013] According to a method for manufacturing a steel ladder provided by the present invention, the step of performing a tooth-expanding operation on the treads in the area where they pass through the vertical beam includes: The expansion head is used to perform an expansion operation along the circumferential direction on the first, second, and third positions of the area where the foot rod passes through the vertical beam; The first position is close to the inner side of the inner wall of the vertical beam, the second position is close to the outer side of the inner wall of the vertical beam, and the third position is close to the inner side of the outer wall of the vertical beam.

[0014] According to a method for manufacturing a steel ladder provided by the present invention, the step of expanding the teeth of the step rod in the area through the vertical beam further includes: controlling the expansion height to be 1-2.5mm during the expansion operation.

[0015] According to a method for manufacturing a steel ladder provided by the present invention, the height of the end of the step stick protruding from the outer side of the vertical beam is 4-10mm. The step of riveting the end of the step stick includes: controlling the riveting width to be 4-10mm and the riveting height to be 1-4mm.

[0016] In a second aspect, the present invention also provides a steel ladder, which is processed using the steel ladder preparation method described above.

[0017] According to the present invention, a steel ladder is used inside the concrete tower of a wind turbine.

[0018] The steel ladder and its manufacturing method provided by this invention facilitate the bending and forming of steel strips based on set parameters to produce vertical beams and treads with high strength. After the two ends of the treads are inserted into the corresponding holes of the two vertical beams, the vertical beams and treads can be connected into one piece by sequentially using a tooth-expanding operation and a riveting operation. During this process, the treads will not crack. This manufacturing method not only has low processing cost, high processing efficiency, and high yield, but also ensures the mechanical strength of the manufactured steel ladder, avoiding the risk of cracking of existing welded ladders in harsh working conditions such as at sea. Furthermore, it has good corrosion resistance, ensuring reliable use in harsh environments. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of the preparation method of the steel ladder provided by the present invention.

[0021] Figure 2 This is a three-dimensional structural diagram of the vertical beam provided by the present invention.

[0022] Figure 3 This is a structural schematic diagram of the cross-section of the vertical beam provided by the present invention.

[0023] Figure 4 This is a three-dimensional structural diagram of the foot pedal provided by the present invention.

[0024] Figure 5 This is a schematic diagram of the cross-section of the foot pedal provided by the present invention.

[0025] Figure 6 This is a schematic diagram of the structure provided by the present invention, in which the two ends of the foot rod are inserted into the corresponding holes of the two vertical beams, and the foot rod is subjected to the tooth expansion operation and the riveting operation respectively.

[0026] Figure 7 This is a structural schematic diagram of the steel ladder provided by the present invention.

[0027] Figure label: 100. Weld; 1. Vertical beam; 111. Inner wall; 112. Outer wall; 11. Perforation; 12. Fixing hole; 101. Recessed structure; 2. Step; 201. Anti-slip surface. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] The following is combined with Figures 1-7 The steel ladder and its manufacturing method provided by the present invention will be described in detail through specific embodiments and application scenarios.

[0030] In the first aspect, such as Figure 1 As shown in the figure, an embodiment of the present invention provides a method for manufacturing a steel ladder, comprising the following steps: In step S100, the steel strip is bent into shape using a roll forming machine to prepare cylindrical vertical beams and treadles.

[0031] Understandably, compared to aluminum alloys, steel strips are less expensive and have high surface hardness and wear resistance. This makes it easy to produce high-strength vertical beams and treads by bending and shaping steel strips. This allows for the production of vertical beams and treads based on steel strips on automated production lines, and then the assembly of these vertical beams and treads into steel ladders. This reduces the production cost of steel ladders while ensuring processing efficiency and structural strength. Steel ladders also have a coefficient of linear expansion that is close to that of concrete, making them easy to install on the concrete towers of wind turbines.

[0032] Meanwhile, the surface of the steel strip usually has an anti-corrosion coating, which ensures that the steel ladders made from the steel strip have good anti-corrosion performance and can be used reliably in harsh environments such as at sea.

[0033] It should be noted that when using roll forming equipment to bend steel strips, the steel strip can be rolled and bent in multiple passes according to the outline shape of the cross-section of the vertical beam to be formed, so as to obtain a cylindrical vertical beam; correspondingly, the steel strip can also be rolled and bent in multiple passes according to the outline shape of the cross-section of the foot pedal to be formed, so as to obtain a cylindrical foot pedal.

[0034] For example, such as Figure 2 and Figure 4As shown, the vertical beam 1 and the footplate 2 formed by bending steel strip are both cylindrical. For example, the cross-section of the vertical beam is roughly rectangular and the cross-section of the footplate is roughly square. The steel strip can be rolled and bent multiple times along the width direction of the steel strip to obtain the vertical beam 1 and the footplate 2. This bending forming process is relatively easy to process, which can make full use of the steel strip and take into account the structural strength and lightweight design of the formed vertical beam and footplate.

[0035] Step S120: Punch holes in the vertical beam to create multiple holes in the vertical beam, with the multiple holes arranged along the extension direction of the vertical beam.

[0036] Understandably, when punching holes in the vertical beam, the shape of the punched holes is adapted to the shape of the end of the treadle so that the end of the treadle can be inserted into the holes; wherein, the shape of the holes can be non-circular, for example, see Figure 2 Multiple perforations 11 are provided on the vertical beam 1 along its extension direction. The perforations 11 are roughly square in shape. Of course, the perforations can also be rectangular, elliptical, "D" shaped or other irregular shapes, which will not be listed here.

[0037] For example, when punching a vertical beam, in order to avoid adverse effects on the overall shape of the vertical beam, the punching operation can be performed with an insert die inserted into the vertical beam. During the punching operation, the punch head passes through the inner wall of the vertical beam, the insert die, and the outer wall of the vertical beam in sequence. The insert die is used to disperse the concentrated stress in the punching area of ​​the vertical beam during the punching operation, so as to prevent the vertical beam from deforming in the punching area.

[0038] The insert mold is made of steel. For example, the insert mold and the vertical beam are made of the same material. The shape of the peripheral wall of the insert mold matches the shape of the inner wall of the vertical beam to ensure that there is no gap between the insert mold and the vertical beam.

[0039] In step S130, the two ends of the foot rod are inserted into the corresponding holes of the two vertical beams, so that at least part of the end of the foot rod is exposed on the outer side of the vertical beam.

[0040] Understandably, in order to improve the production efficiency of steel ladders, an integrated ladder forming machine can be used to assemble the steel ladders. For example, two vertical beams are placed in the first hopper of the integrated ladder forming machine, and no less than two treads are placed in the second hopper. After the integrated ladder forming machine is started, it will automatically set the two vertical beams side by side and align the ends of the two vertical beams. Then, each tread is inserted into the corresponding hole of the two vertical beams, ensuring that the end of the tread protrudes from the outer side of the vertical beam.

[0041] In practical applications, manual assembly can also be used, where each step bar is inserted into the corresponding holes of the two vertical beams to assemble the steel ladder. This will not be elaborated on here.

[0042] Step S140: Perform a threading operation on the area where the foot rod passes through the vertical beam, and perform a riveting operation on the end of the foot rod to connect the vertical beam and the foot rod into one piece. The steel strip must meet the following parameters: thickness of 0.5-3mm, yield strength of 230-420MPa, tensile strength of 330-560MPa, and elongation of 20%-35%.

[0043] Understandably, when expanding the teeth of the foot pedal, the expansion head of the expansion machine can be inserted from the end of the foot pedal into the area where the foot pedal passes through the vertical beam. Expanding the teeth in the area where the foot pedal passes through the vertical beam causes the peripheral wall of the foot pedal to expand radially outward, thereby fixing the foot pedal to the vertical beam and preventing the foot pedal from moving relative to the perforation along its extension direction.

[0044] When riveting the foot bar, riveting equipment (such as an eccentric riveting machine or riveting fixture) can be used to rivet the part of the foot bar that protrudes from the outer side of the vertical beam. This allows control over the end of the foot bar 2 along... Figure 6 The arrow points outward until the outward-curving structure formed at the end of the footplate contacts the outer wall of the vertical beam.

[0045] Two sets of riveting equipment can be used to rivet both ends of the pedal simultaneously, which can effectively improve the efficiency of the riveting operation. Based on the limiting effect between the outward-turned structure formed by riveting and the outer side wall of the vertical beam, it is further ensured that each pedal is securely limited between the two vertical beams.

[0046] Meanwhile, compared to the method of manufacturing steel ladders by welding, the present invention can quickly and reliably connect the vertical beam and the treads into one piece by sequentially performing threading and riveting operations on the treads. The production cycle of steel ladders manufactured in this way is much shorter than that of steel ladders manufactured by welding, and the structure of the steel ladders manufactured is more reliable, and there will be no situation where the treads detach from the vertical beams.

[0047] Furthermore, compared to welding, this invention uses a purely mechanical cold working method to manufacture and assemble the vertical beams and steps. This ensures that the surface structure of the material is not damaged during the preparation of the steel ladder, thus guaranteeing that the prepared steel ladder has good corrosion resistance.

[0048] In practical applications, the steel strip can be set to meet the following parameters: thickness of 0.5-3mm, yield strength of 230-420MPa, tensile strength of 330-560MPa, and elongation of 20%-35%. This design facilitates the bending and forming of the steel strip, ensuring the preparation of vertical beams and treadles with high strength structures. It can also effectively prevent cracking of the treadles during the tooth-expanding and riveting operations.

[0049] In order to find steel strips that meet the requirements for manufacturing steel ladders, the inventors conducted trial production operations of steel ladders based on steel strips of various materials, as detailed below:

[0050] Based on the parameters of the steel strips in Examples 1 to 3 and Comparative Examples 1 to 2 in the table above, steel ladders can be successfully manufactured using the steel strips shown in Examples 1 to 3. As the thickness of the steel strip gradually increases, the mechanical strength of the manufactured steel ladder also gradually increases. However, the greater the thickness of the steel strip, the more difficult it is to bend and form. When the steel strip thickness is large, the material of the steel strip can be appropriately configured, that is, selecting a steel strip with relatively low yield strength, tensile strength, and elongation. This can reduce the processing difficulty of the steel strip while preventing cracking of the treadle during the tooth-expanding and riveting operations. Therefore, the parameter settings for the steel strip must ensure that the yield strength, tensile strength, and elongation of the steel strip are negatively correlated with the thickness of the steel strip.

[0051] However, for the steel strip provided in Comparative Example 1 above, the selected steel strip has a relatively small thickness, but the steel strip has a relatively large yield strength and tensile strength. Although this steel strip is easy to bend and form, the treads are prone to cracking when the teeth are expanded. Furthermore, the mechanical strength of the prepared steel ladder is difficult to meet the requirements of practical applications.

[0052] The steel strip provided in Comparative Example 2 has a relatively large thickness and high yield strength and tensile strength, making it difficult to bend and form. This can easily lead to cracking of the treads during riveting operations. While this type of steel strip can produce steel ladders with higher mechanical strength to some extent, the overall processing of the steel ladders is difficult, resulting in a high scrap rate and making it unsuitable for automated production on a production line.

[0053] It is evident that not all steel strips can be used to manufacture steel ladders that meet the standard requirements. When the relevant parameters of the steel strip do not meet the requirements, the mechanical strength of the manufactured steel ladder often fails to meet the design requirements, or the mechanical strength of the steel ladder meets the design requirements, but the processing difficulty of the steel ladder increases, the processing efficiency decreases, or the treads crack during the tooth expansion or riveting operation, resulting in an increased scrap rate.

[0054] Regarding the steel ladders prepared with the steel strips according to the above parameters provided in the embodiments of the present invention (e.g., embodiments 1 to 3), taking steel ladders with widths of 470mm and 575mm as examples, after the steel ladders are prepared, the mechanical properties of the vertical beams and steps on the steel ladders are tested. The specific test results are as follows: According to the test data above, for the two types of steel ladders with widths of 470mm and 575mm, the mechanical properties of the vertical beams and steps of the steel ladders meet the requirements of the standard test requirements in different regions. This shows that the overall mechanical strength of the steel ladder prepared by this invention is much higher than the standard requirements.

[0055] As can be seen from the above, the steel ladder manufacturing method of the present invention facilitates the bending and forming of steel strips based on set parameter indicators to prepare vertical beams and treads with high strength structures. After the two ends of the treads are inserted into the corresponding holes of the two vertical beams, the vertical beams and treads are connected into one piece by sequentially using tooth-expanding and riveting operations. During this process, the treads will not crack. This manufacturing method not only has low processing cost, high processing efficiency, and high yield, but also ensures the mechanical strength of the prepared steel ladder, avoiding the risk of cracking of existing welded ladders in harsh working conditions such as at sea. It also has good corrosion resistance and can ensure reliable use in harsh environments.

[0056] In some embodiments, the step of using a roll forming equipment to bend a steel strip to prepare a cylindrical vertical beam, as shown in this invention, includes: Based on the outline shape of the cross-section of the vertical beam to be formed, determine the width of the first steel strip used to prepare the vertical beam, and then feed the first steel strip. While controlling the first steel strip to be fed at the first speed, the roll forming equipment is controlled to perform multiple roll forming passes along the feeding direction of the first steel strip, gradually bending the first steel strip in the width direction into a cylindrical vertical beam to be welded; Weld the weld seams on the vertical beam components to be welded.

[0057] It is understandable that, in order to facilitate processing, when feeding the first steel strip along its extension direction, the steel strip is gradually rolled into a vertical beam to be welded along its width direction. The perimeter of the vertical beam to be formed is matched with the width of the first steel strip, so the width of the first steel strip used to prepare the vertical beam is determined according to the outline shape of the cross-section of the vertical beam to be formed.

[0058] For example, such as Figure 2 and Figure 3 As shown, the cross-section of the vertical beam 1 to be formed is approximately rectangular. The vertical beam 1 includes a first top wall, a first left side wall, a first bottom wall, and a first right side wall. The first top wall, the first left side wall, the first bottom wall, and the first right side wall are connected end to end in an arc-shaped structure formed by roll forming. The width of the first steel strip W1 = [L1 + θ1 × Σ(r1 + k × t1)] × (1 ± δ); Where L1 is the sum of the straight line lengths corresponding to the first top wall, the first left side wall, the first bottom wall and the first right side wall, θ1 is the central angle of each arc structure on the vertical beam, r1 is the radius of curvature of each arc structure on the vertical beam, k is the neutral layer coefficient, t1 is the thickness of the first steel strip, and δ is the correction coefficient, with a value of 0.5%-1%.

[0059] In practical applications, when feeding the first steel strip, the first steel coil is placed on the first feeding fixture, and the uncoiled first steel strip on the first steel coil is passed into the roll forming equipment. The first feeding fixture is used to control the uncoiling of the first steel coil, which is formed by winding the first steel strip.

[0060] When the first steel strip is bent and formed, the first feeding fixture controls the first steel strip to be fed at a first speed (e.g., 8-16 m / min). The first set of roller forming dies in the roller forming equipment is controlled to flatten and feed the first steel strip. The subsequent sets of roller forming dies each undertake a certain bending and forming task. The roller forming equipment can be equipped with 15-25 sets of roller forming dies.

[0061] It should be noted that bending the first steel strip into the desired product (such as a vertical beam to be welded) is a gradual process. In this process, each pass or each pair of forming rollers applies only a limited bending deformation to the material. Only in this way can the required bending deformation be obtained without stretching the first steel strip. Too few forming passes will easily cause dimensional deviations and distortion in the cold-bent profile; too many forming passes will increase tooling costs.

[0062] During the start-up and operation of the roll forming equipment, the first steel strip undergoes multiple roll forming processes according to the shape of each set of roll forming dies until the vertical beam to be welded is formed. Parameters can be configured via the control panel of the roll forming equipment to adjust the roll forming gap between the upper and lower forming rollers corresponding to each set of roll forming dies, thereby producing the vertical beam to be welded to the required specifications. Initially, manual parameter configuration of the control panel is required. During operation, the roll forming equipment automatically corrects the roll forming gap based on data feedback from each roll forming station.

[0063] After the vertical beam to be welded is formed, the production line or automatic transfer equipment transfers the vertical beam to be welded to the welding area. After the welding equipment detects the vertical beam to be welded, it will automatically weld the weld seam on the vertical beam to be welded.

[0064] In some embodiments, the step of the controlled roll forming equipment of the present invention performing multiple roll forming passes along the feeding direction of the first steel strip to gradually bend the first steel strip into a cylindrical vertical beam to be welded includes: The first region of the first steel strip is rolled to create a groove shape on the first steel strip. The groove shape is used to form an inward concave structure on the outer side of the vertical beam. According to the outline shape of the cross-section of the vertical beam to be formed, along the width direction of the first steel strip, the portion of the first steel strip except for the first region is gradually bent until the two sides of the first steel strip are aligned to obtain the vertical beam to be welded.

[0065] It is understandable that when roll forming the vertical beam to be welded, a step-by-step roll forming method is adopted. First, the groove shape is rolled, and then the first steel strip is rolled and bent along the width direction of the first steel strip. This design facilitates the control of the roll forming shape of the first steel strip step by step, and improves the roll forming efficiency of the vertical beam to be welded.

[0066] For example, considering that the vertical beam is a product obtained after the weld seam of the vertical beam to be welded is completed, the vertical beam to be welded has a substantially the same cross-sectional structure as the vertical beam. According to... Figure 3 As shown in the cross-section of the vertical beam 1, the concave structure 101 is formed on the first top wall of the vertical beam 1. The concave structure 101 is groove-shaped and extends along the length of the vertical beam 1. Designing the vertical beam 1 with the concave structure 101 increases its structural strength and ensures that the end of the step bar 2 does not protrude from the outer surface of the vertical beam 1 after riveting, which is beneficial for the installation of the steel ladder. (See [reference]). Figure 6 and Figure 7 .

[0067] At the same time, such as Figure 3As shown, weld 100 is located on the first bottom wall of vertical beam 1 and is located near the first left side wall of vertical beam 1. When punching vertical beam 1, this design can prevent weld 100 from being in the punching area, thereby reducing the impact of punching operation on the overall structural strength of vertical beam 1.

[0068] In some embodiments, the preparation method of the present invention, after welding the weld seam on the vertical beam to be welded, further includes: Once it is confirmed that the dimensions of the vertical beam to be welded meet the requirements, zinc plating is performed on the weld bead on the vertical beam to be welded.

[0069] Understandably, after the vertical beam to be welded is roll-formed, a dimensional measuring fixture is needed to inspect its dimensions. The accuracy of the dimensional measuring fixture should be controlled within ±0.2mm. If the dimensions of the vertical beam to be welded do not meet the requirements, the roll-forming equipment will adjust its parameters, and the vertical beam to be welded will be re-made based on the adjusted parameters.

[0070] After confirming that the dimensions of the completed vertical beam to be welded meet the requirements, zinc is applied to the weld along its extension direction. Considering that the first steel strip used in the preparation of the vertical beam to be welded in this invention has its own anti-corrosion coating, applying zinc to the weld at this time can enhance the corrosion resistance of the weld, thereby ensuring that the entire vertical beam prepared has good corrosion resistance.

[0071] It should be noted that after the vertical beam is prepared, it can be cut into multiple sections according to the set length according to the actual application requirements. For example, when an insert mold is inserted into the vertical beam, a punching mechanism can be used to punch the vertical beam to a fixed length. The fixed length punching process makes the material utilization rate close to 100%. The punching process does not produce iron filings, thus avoiding iron filings adhering to the material surface and causing surface rust.

[0072] In some embodiments, the punching operation on the vertical beam shown in this invention further includes: Multiple fixing holes are constructed on the vertical beam, with at least two fixing holes located on both sides of the multiple through holes along the extension direction of the vertical beam; The fixing holes are used to connect the opposite ends of two adjacent steel ladders.

[0073] It is understandable that for ladders used on concrete towers in the wind power industry, the ladders are relatively long, and multiple steel ladders prepared by this invention need to be connected in sequence to assemble a ladder that can be used on concrete towers.

[0074] like Figure 2As shown, the fixing hole 12 shown in this invention can be a through hole. Each of the two ends of each vertical beam 1 of the steel ladder is provided with a fixing hole 12. Multiple through holes 11 are provided between the two fixing holes 12 of the vertical beam 1. The number of through holes 11 can be more than three, and there is no specific limitation on this.

[0075] When connecting two adjacent steel ladders, a connecting rod can be inserted into the vertical beams corresponding to the two adjacent steel ladders. The first connecting hole at the first end of the connecting rod corresponds to the fixing hole on the vertical beam corresponding to one steel ladder, and the second connecting hole at the second end of the connecting rod corresponds to the fixing hole on the vertical beam corresponding to the other steel ladder. A bolt or other locking device that can pass through the first connecting hole (second connecting hole) and the fixing hole can be used to connect the vertical beam and the connecting rod into one unit to complete the connection of the opposite ends of the two adjacent steel ladders.

[0076] In some embodiments, the step of using a roll forming device to bend a steel strip to prepare a cylindrical treadle, as shown in this invention, includes: Based on the outline shape of the cross-section of the treadle to be formed, determine the width of the second steel strip used to prepare the treadle, and then feed the second steel strip. While controlling the second steel strip to be fed at the second speed, the roll forming equipment is controlled to perform multiple roll forming passes along the feeding direction of the second steel strip, gradually bending the second steel strip in the width direction into a cylindrical treadle to be welded; Weld the weld seams on the footplate to be welded.

[0077] Understandably, in order to facilitate processing, when feeding the second steel strip along its extension direction, the steel strip is gradually rolled into a foot rod to be welded along its width direction. The circumference of the foot rod to be formed matches the width of the second steel strip, and the width of the second steel strip used to prepare the foot rod is determined according to the outline shape of the cross-section of the foot rod to be formed.

[0078] For example, such as Figure 4 and Figure 5 As shown, the cross-section of the forming foot roller 2 is approximately square. The foot roller 2 includes a second top wall, a second left side wall, a second bottom wall, and a second right side wall. The second top wall, second left side wall, second bottom wall, and second right side wall are connected end to end in an arc-shaped structure formed by roll forming. The width of the second steel strip is W2 = [L2 + θ2 × Σ (r2 + k × t2)] × (1 ± δ). Where L2 is the sum of the straight line lengths corresponding to the second top wall, the second left side wall, the second bottom wall, and the second right side wall, θ2 is the central angle of each arc structure on the pedal, r2 is the radius of curvature of each arc structure on the pedal, k is the neutral layer coefficient, t2 is the thickness of the second steel strip, and δ is the correction coefficient, with a value of 0.5%-1%.

[0079] In practical applications, when feeding the second steel strip, the second steel coil is placed on the second feeding fixture, and the unwound second steel strip on the second steel coil is passed into the roll forming equipment. The second feeding fixture is used to control the unwinding of the second steel coil, which is formed by winding the second steel strip.

[0080] When the second steel strip is bent and formed, the second steel strip is fed at a second speed (e.g., 10-20 m / min) based on the second feeding tooling. The first set of roller forming dies in the roller forming equipment is controlled to flatten and feed the second steel strip. The subsequent multiple sets of roller forming dies each undertake a certain bending and forming task. The roller forming equipment can be set with 15-25 sets of roller forming dies.

[0081] It should be noted that bending the second steel strip into the desired product (such as a footplate to be welded) is a gradual process. In this process, each pass or each pair of forming rollers applies only a limited bending deformation to the material. Only in this way can the required bending deformation be obtained without stretching the second steel strip. Too few forming passes will easily cause dimensional deviations and distortion in the cold-bent profile; too many forming passes will increase tooling costs.

[0082] During the start-up and operation of the roll forming equipment, the second steel strip undergoes multiple roll forming processes according to the shape of each set of roll forming dies until the foot rod to be welded is formed. Parameters can be configured via the control panel of the roll forming equipment to adjust the roll forming gap between the upper and lower forming rollers corresponding to each set of roll forming dies, thereby producing the foot rod to be welded to the required specifications. Initially, manual parameter configuration of the control panel is required. During operation, the roll forming equipment automatically corrects the roll forming gap based on data feedback from each roll forming station.

[0083] After the foot pedal is formed, the production line or automatic transfer equipment transfers the foot pedal to the welding area. After the welding equipment detects the foot pedal, it will automatically weld the weld seam on the foot pedal.

[0084] In some embodiments, the step of the controlled roll forming equipment of the present invention performing multiple roll forming passes along the feeding direction of the second steel strip to gradually bend the second steel strip into a cylindrical treadle to be welded part in its width direction includes: At least one second region of the second steel strip is rolled to create an embossed shape on the second steel strip, the embossed shape being used to form an anti-slip surface on the surface of the pedal. According to the outline shape of the cross-section of the pedal to be formed, along the width direction of the second steel strip, the part of the second steel strip except for the second region is gradually bent until the two sides of the second steel strip are aligned to obtain the pedal to be welded.

[0085] It is understandable that when roll forming the foot pedal to be welded, a step-by-step roll forming method is adopted. First, the concave and convex shape is rolled, and then the second steel strip is rolled and bent along the width direction of the second steel strip. This design facilitates the control of the roll forming shape of the second steel strip step by step, and improves the roll forming efficiency of the foot pedal to be welded.

[0086] For example, considering that the treadle is a product obtained after welding the treadle to be welded part, the treadle to be welded part and the treadle have approximately the same cross-sectional structure. According to... Figure 5 As can be seen from the cross-section of the pedal 2 shown, the concave and convex shapes are formed on the second top wall, the second left side wall, the second bottom wall and the second right side wall of the pedal. Based on the concave and convex shapes, an anti-slip surface 201 is formed on the surface of the pedal 2. The concave and convex shapes can be corrugated shapes, which include multiple corrugated stripes arranged side by side. Each corrugated stripe bends back and forth along the length of the pedal, and the height of the corrugated stripe can be 0.2-0.5mm.

[0087] In practical applications, by designing concave and convex shapes, especially corrugated shapes, the structural strength of the pedal can be improved, and the surface of the pedal can form an anti-slip surface, which has an anti-slip effect and meets the anti-slip texture design requirements of EN ISO 14122-4 and EN131-2 standards.

[0088] Meanwhile, by setting a corrugated pattern on the surface of the pedal, the corrugated pattern will expand to a certain extent during the expansion and riveting operations of the pedal, so as to effectively compensate for the material extension and deformation on the pedal and ensure that the pedal will not crack during the expansion and riveting operations.

[0089] Furthermore, such as Figure 5 As shown, weld 100 is located on the arc-shaped structure between the second left side wall and the second bottom wall of pedal 2. Weld 100 of pedal 2 extends along the length of pedal 2. Based on the welding operation of the weld on the pedal to be welded, the formed pedal can be obtained.

[0090] In some embodiments, the welding method for the weld seam on the footplate to be welded, as shown in this invention, further includes: Once it is confirmed that the dimensions of the footplate to be welded meet the requirements, zinc plating is performed on the weld bead on the footplate to be welded.

[0091] Understandably, after the roller forming of the foot pedal component is completed, a dimensional measuring fixture is needed to inspect its dimensions. The accuracy of the dimensional measuring fixture should be controlled within ±0.2mm. If the dimensions of the foot pedal component do not meet the requirements, the roller forming equipment will adjust its parameters, and the foot pedal component will be re-made based on the adjusted parameters.

[0092] After confirming that the dimensions of the welded foot pedal meet the requirements, zinc is applied to the weld along its extension direction. Considering that the second steel strip used in this invention has a built-in anti-corrosion coating, applying zinc to the weld enhances its corrosion resistance, thus ensuring that the entire foot pedal has good corrosion resistance.

[0093] It should be noted that after the pedal is prepared, it can be cut into multiple sections according to the set length according to the actual application requirements. For example, when an insert mold is inserted into the pedal, a punching mechanism can be used to punch the pedal to a fixed length. The fixed length punching process makes the material utilization rate close to 100%. The punching process does not produce iron filings, thus avoiding iron filings adhering to the material surface and causing surface rust.

[0094] In some embodiments, the step of expanding the teeth of the footplate in the area passing through the vertical beam, as shown in this invention, includes: The expansion head is used to perform expansion operations along the circumferential direction on the first, second, and third positions of the area where the foot rod passes through the vertical beam; The first position is close to the inner side of the inner wall of the vertical beam, the second position is close to the outer side of the inner wall of the vertical beam, and the third position is close to the inner side of the outer wall of the vertical beam.

[0095] It is understandable that the expansion head of the integrated expansion machine can be used to simultaneously expand the teeth at the first, second, and third positions on the pedal. The first position is... Figure 6 The position indicated by D1 is the second position. Figure 6 The position indicated by D2 is the third position. Figure 6 The position indicated by D3. When the tooth-expanding operation is performed on the first, second, and third positions along the circumference of the pedal, three concentric protrusions can be formed on the corresponding positions on the side wall of the pedal.

[0096] By performing a tooth-expanding operation on the first and second positions of the pedal, the inner wall of the vertical beam can be confined between the protrusions formed by the tooth expansion based on the first and second positions, thereby preventing the pedal from moving relative to the vertical beam along its extension direction.

[0097] By performing a tooth-expanding operation on the third position of the pedal, a protrusion that abuts against the inner side of the outer side wall of the vertical beam can be formed on the side wall of the pedal. This further prevents the pedal from moving relative to the outside of the vertical beam along its extension direction. Furthermore, based on the limiting effect of the protrusion formed by tooth expansion at the third position of the pedal, it is also convenient to reliably rivet the part of the pedal end that protrudes from the outer side of the vertical beam.

[0098] It should be noted that, in practical applications, the arc-shaped structures corresponding to the first, second, and third positions on the pedal can be expanded by toothing. This operation ensures that the expanded toothing area avoids the area where the anti-slip surface on the pedal is located, which helps to reduce the difficulty of the toothing operation and prevents the pedal from cracking during the toothing operation.

[0099] In some embodiments, the step of expanding the teeth of the footplate in the area through which the vertical beam is inserted, as shown in this invention, further includes: controlling the expansion height to be 1-2.5 mm during the expansion operation.

[0100] Understandably, during the tooth-expanding process, the tooth-expanding height needs to be strictly controlled. If the tooth-expanding height is too small, the pedal cannot be fixed to the vertical beam; if the tooth-expanding height is too large, the pedal is prone to cracking. Based on the pedal made of the steel strip selected in this invention, by controlling the tooth-expanding height to 1-2.5mm, the protrusion formed by the tooth expansion can connect the pedal and the vertical beam into one unit, and can also effectively prevent the pedal from cracking during the tooth-expanding process.

[0101] In practical applications, the expansion height can be specifically set to 1mm, 1.5mm, 2mm, 2.5mm and other suitable dimensions, without any specific limitation.

[0102] In some embodiments, the height of the end of the foot bar protruding from the outer side of the vertical beam is 4-10mm. The step of riveting the end of the foot bar includes: controlling the riveting width to be 4-10mm and the riveting height to be 1-4mm.

[0103] Understandably, after using a thread-expanding machine to expand the threads at the first, second, and third positions on the pedal, the riveting head of the thread-expanding machine can be used to repeatedly roll the portion of the pedal end exposed on the outer side of the vertical beam, thus shaping the end of pedal 2 as follows: Figure 6 Fold in the direction shown to complete the riveting operation, ensuring that the outward-folded structure formed by riveting is limited to the outer side of the outer wall of the vertical beam. That is, the outward-folded structure can be limited to the protrusion formed by the toothing method at the third position of the foot rod on both sides of the outer wall of the vertical beam, ensuring that the foot rod and the vertical beam are firmly connected as one, which can effectively prevent the foot rod from falling off the vertical beam.

[0104] In practical applications, the outward-facing structure formed by riveting can be an arc-shaped structure. The riveting width can be specifically set to 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm and other suitable dimensions, without specific limitations. The riveting height can be set to 1mm, 2mm, 3mm, 4mm and other suitable dimensions, without specific limitations. However, it is necessary to ensure that the design dimensions of the riveting width and riveting height can be organically combined to prevent the pedal from cracking during the riveting process.

[0105] In the second aspect, such as Figure 7 As shown, the present invention also provides a steel ladder, which includes vertical beams 1 and footboards 2. The footboards 2 are disposed between two vertical beams 1 arranged side by side. The steel ladder is processed by the steel ladder manufacturing method described above.

[0106] Among them, steel ladders are used inside the concrete tower of wind turbines.

[0107] Since the steel ladder is processed based on the steel ladder preparation method shown in the above embodiments, and the specific implementation method of the steel ladder preparation method refers to the above embodiments, the steel ladder shown in this embodiment includes all the technical solutions of the above embodiments and can achieve the corresponding technical effects. Therefore, it has at least all the beneficial effects obtained by all the technical solutions of the above embodiments, which will not be repeated here.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing a steel ladder, characterized in that, include: The steel strip is bent into shape using a roll forming machine to prepare cylindrical vertical beams and treadles respectively; The vertical beam is punched to create a plurality of through holes, which are arranged along the extension direction of the vertical beam. The two ends of the foot rod are inserted into the corresponding holes of the two vertical beams, with at least a portion of the end of the foot rod exposed on the outer side of the vertical beam; The area where the foot rod passes through the vertical beam is subjected to a threading operation, and the end of the foot rod is subjected to a riveting operation to connect the vertical beam and the foot rod into one piece; The steel strip meets the following parameters: thickness of 0.5-3mm, yield strength of 230-420MPa, tensile strength of 330-560MPa, and elongation of 20%-35%.

2. The method for preparing the steel ladder according to claim 1, characterized in that, The steps for preparing cylindrical vertical beams by bending steel strips using roll forming equipment include: Based on the outline shape of the cross-section of the vertical beam to be formed, determine the width of the first steel strip used to prepare the vertical beam, and then feed the first steel strip. While controlling the first steel strip to be fed at the first speed, the roll forming equipment is controlled to perform multiple roll forming passes along the feeding direction of the first steel strip, gradually bending the first steel strip in the width direction into a cylindrical vertical beam to be welded. Welding is performed on the weld seams of the vertical beam to be welded.

3. The method for preparing the steel ladder according to claim 2, characterized in that, The step of controlling the roll forming equipment to sequentially perform multiple roll forming passes along the feeding direction of the first steel strip, gradually bending the first steel strip in its width direction into a cylindrical vertical beam to be welded, includes: A first region of the first steel strip is rolled to create a groove shape on the first steel strip, the groove shape being used to form an inward concave structure on the outer surface of the vertical beam; According to the outline shape of the cross-section of the vertical beam to be formed, along the width direction of the first steel strip, the portion of the first steel strip other than the first area is gradually bent until the two sides of the first steel strip are aligned to obtain the vertical beam to be welded.

4. The method for preparing a steel ladder according to claim 2, characterized in that, After welding the weld seams on the vertical beam to be welded, the preparation method further includes: Once it is confirmed that the dimensions of the vertical beam to be welded meet the requirements, zinc supplementation is performed on the weld bead on the vertical beam to be welded.

5. The method for preparing a steel ladder according to claim 1, characterized in that, The punching operation on the vertical beam also includes: Multiple fixing holes are constructed on the vertical beam, and at least two of the fixing holes are located on both sides of the multiple through holes along the extension direction of the vertical beam; The fixing hole is used to connect the opposite ends of two adjacent steel ladders.

6. The method for preparing a steel ladder according to claim 1, characterized in that, The steps for preparing a cylindrical treadle by bending a steel strip using a roll forming machine include: Based on the outline shape of the cross-section of the foot pedal to be formed, determine the width of the second steel strip used to prepare the foot pedal, and then feed the second steel strip. While controlling the second steel strip to be fed at the second speed, the roll forming equipment is controlled to perform multiple roll forming passes along the feeding direction of the second steel strip, gradually bending the second steel strip in its width direction into a cylindrical treadle to be welded; Welding is performed on the weld seam of the footplate to be welded.

7. The method for manufacturing a steel ladder according to claim 6, characterized in that, The step of controlling the roll forming equipment to sequentially perform multiple roll forming passes along the feeding direction of the second steel strip, gradually bending the second steel strip into a cylindrical treadle to be welded, includes: At least one second region of the second steel strip is rolled to create an embossed pattern on the second steel strip, the embossed pattern being used to form an anti-slip surface on the surface of the footplate; According to the outline shape of the cross-section of the foot pedal to be formed, along the width direction of the second steel strip, the portion of the second steel strip other than the second region is gradually bent until the two sides of the second steel strip are aligned to obtain the foot pedal to be welded.

8. The method for preparing a steel ladder according to claim 6, characterized in that, The preparation method further includes welding the weld seam on the footplate to be welded. After confirming that the dimensions of the footplate to be welded meet the requirements, zinc supplementation is performed on the weld bead on the footplate to be welded.

9. The method for manufacturing a steel ladder according to any one of claims 1 to 8, characterized in that, The step of expanding the teeth of the foot rod in the area through which it passes the vertical beam includes: The expansion head is used to perform an expansion operation along the circumferential direction on the first, second, and third positions of the area where the foot rod passes through the vertical beam; The first position is close to the inner side of the inner wall of the vertical beam, the second position is close to the outer side of the inner wall of the vertical beam, and the third position is close to the inner side of the outer wall of the vertical beam.

10. The method for preparing a steel ladder according to claim 9, characterized in that, The step of performing a tooth-expanding operation on the foot rod in the area through which it passes the vertical beam further includes: When performing the tooth expansion operation, the expansion height is controlled to be 1-2.5mm.

11. The method for manufacturing a steel ladder according to any one of claims 1 to 8, characterized in that, The end of the foot bar protrudes 4-10mm above the outer surface of the vertical beam. The step of riveting the end of the foot bar includes: Control the riveting width to 4-10mm and the riveting height to 1-4mm.

12. A steel ladder, characterized in that, The steel ladder is manufactured using the steel ladder manufacturing method as described in any one of claims 1 to 11.

13. The steel ladder according to claim 12, characterized in that, The steel ladder is used inside the concrete tower of the wind turbine.

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