Integrated polymer step structure for use in telescopic ladder

Abstract

Disclosed in the present utility model is an integrated polymer step structure for use in a telescopic ladder, comprising a step body that comprises a step located in the middle and sleeves located on two sides of the step and capable of being connected to telescopic columns; the step and the sleeves are formed by a polymer material into an inseparable whole by means of a molding technology; the step and the sleeves are smoothly connected by means of an as-molded fillet; the step has a stepping surface, two side surfaces, and a processed bottom surface; each sleeve is provided with a hoop and a hoop hole; the stepping surface is provided with an anti-slip protrusion-and-recess pattern and wear-resistant ribs; and the processed bottom surface is provided with reinforcing ribs and an anti-deformation assembly. The present utility model breaks through the long-standing limitation that ladder steps in the field of telescopic ladders can be made of only aluminum alloy or stainless steel; by means of careful experiments and design improvements, the utility model overcomes the defect that polymer material previously has not been suitable for use in ladder steps in the field of telescopic ladders; and the utility model is particularly suitable for molding, has low mass production costs, and has significant improvements in multiple aspects.

Description

A special integral polymer step structure for telescopic ladders Technical Field

[0001] This utility model relates to the field of data measurement, analysis and early warning, and in particular to an integral polymer pedal structure for telescopic ladders. Background Technology

[0002] The steps of telescopic ladders are generally made of aluminum alloy or stainless steel. Metal has good dimensional stability and structural strength, can withstand abuse by people on the steps, and has good portability and safety. However, the connection between aluminum alloy or stainless steel steps and telescopic rods is relatively inconvenient. The industry uses additional plastic connecting sleeves for connection. However, there is currently no plastic material or structure in the industry to replace aluminum alloy or stainless steel steps. This requires a lot of time, financial resources, energy and innovation to try out new materials and corresponding new structures. According to the different characteristics of raw materials and molding process limitations, it is necessary to develop and design new structural forms to enable the manufacture of telescopic ladder steps using polymer materials.

[0003] The technical requirements for retractable ladder treads differ from those for ordinary stair treads. Retractable ladder treads are used in scenarios requiring frequent movement, so they must be lightweight and withstand frequent extension, retraction, and locking actions. Conventional polymer materials and conventional structural designs cannot meet these basic requirements. Aluminum alloy and stainless steel treads have good conductivity, making them slippery and easily damaged by impacts. Material fatigue damage often occurs suddenly and unexpectedly. They lack cushioning in the event of collisions, which can easily lead to vibration injuries. Furthermore, the material costs are high. Retractable ladders are used in complex environments, requiring them to be usable in dry, wet, acidic, alkaline, and electrically charged conditions. Conventional methods offer little room for cost reduction and efficiency improvement.

[0004] CN201056976Y discloses a ladder and its steps, including leg tubes and steps installed between the two leg tubes. The steps include a plastic step and a metal support rod, which supports and connects the plastic step. In this invention, the metal support rod supports and connects the plastic step, thus providing both sufficient support strength and a large enough surface area. Furthermore, it offers the following advantages: firstly, reduced manufacturing costs; secondly, the connection between the steps and leg tubes via the metal support rod is convenient and strong. Although this patent uses a plastic step, it also reveals that without a special structural design and polymer materials, an additional metal support rod is still necessary. However, plastic steps with added metal support rods, or a combination of metal support rods and plastic steps, are not suitable for use on telescopic ladders that require frequent extension, retraction, movement, and fixation.

[0005] CN207393095U discloses a retractable ladder for viewing platforms, including steps, a telescopic mechanism, a ladder body, a crossbar, a knob, a fixing frame, a support frame, a mounting plate, and a pivot. This ladder has a compact structure and is easy to use. The ladder is retractable for climbing viewing platforms. The telescopic mechanism is hydraulically controlled, offering high flexibility. After the ladder is raised, the knob can be fixed to prevent slippage, ensuring high stability. A pivot is movably connected to the top of the support frame, allowing adjustment of the support frame's tilt angle to stabilize the ladder body and prevent slippage that could cause injury. The mounting plate has an array of screw holes for securely mounting the support frame onto the crossbar. Anti-slip pads are provided on the steps to improve safety when stepping on them. The bottom of the support frame has an angled slope to increase the contact area with the ground when tilted, resulting in strong stability during operation. This ladder structure does not require replacement of its steps with polymer materials.

[0006] CN208456486U discloses a telescopic ladder for construction, including an anti-slip plate, a first sleeve, a second sleeve, a third sleeve, a first step, a second step, a connecting plate, a hook, a light, a first limiting post, a second limiting post, a control panel, a first sleeve rod, a second sleeve rod, and limiting springs. The top of the anti-slip plate is symmetrically fixed with a first sleeve. T-shaped grooves are symmetrically formed at both ends of the top of the anti-slip plate, and a first sleeve rod is slidably connected within each T-shaped groove. Limiting springs are symmetrically fixed to the side wall of each first sleeve rod near the first sleeve. The end of each limiting spring away from the first sleeve rod is fixedly connected to the first sleeve. A first limiting post is fixed to the top side wall of the first sleeve rod near the first sleeve. A second sleeve is slidably connected within the first sleeve. A first limiting hole is formed on the top side wall of the first sleeve. This telescopic ladder for construction is easy to handle and carry, and has good safety performance. This ladder is essentially a metal step ladder and cannot be replaced by conventional plastic steps.

[0007] CN220101165U discloses a self-locking telescopic ladder, including a ladder body comprising a front telescopic ladder and a rear telescopic ladder. Both the front and rear telescopic ladders include a left support telescopic rod and a right support telescopic rod, each composed of multiple sub-rods. The lower part of the upper sub-rod is inserted into the upper part of the adjacent lower sub-rod. A step block is provided between the tops of each corresponding left and right sub-rod, and connecting blocks are fixed to both ends of the step block. An upwardly extending stepped through-hole is formed in the center of the bottom surface of the outer end of the connecting block. The top of the sub-rod is engaged in the lower large-diameter section of the corresponding stepped through-hole, and the lower part of the upper sub-rod is inserted into the upper through-hole of the stepped through-hole and the top of the sub-rod. This design allows the front and rear telescopic ladders to be brought together for easy storage and placement, with good performance. However, no instructions are provided regarding the use of polymer step blocks.

[0008] CN109630005A discloses a height-adjustable and easily movable ladder, comprising a ladder body, a lifting device, and a moving device. The ladder body includes a manually telescopic rod, footboards, a seat, a fixed support plate, a pivot I, and a rotating joint. The lifting device includes a telescopic support ladder, a support ladder telescopic controller, a movable long step, and a fixed long step. The moving device includes casters, a caster locking device, and a caster locking controller. The pneumatic push rod device is installed on the upper part of the four legs of the ladder; the manually telescopic part consists of the four legs of the ladder and the support part that pushes the ladder to move; the moving device is installed at the bottom of the four legs of the ladder. This invention has a simple structure, is easy to use and carry, can be retracted when not in use, occupies little space, can be easily unfolded when in use, can moderately raise the height of the ladder, and can move left and right. This technology still does not disclose any technical features or beneficial inspirations related to polymer footboards.

[0009] CN201377284Y discloses a plastic-pedal aluminum ladder, consisting of a left aluminum ladder assembly and a right aluminum ladder assembly connected by hinges. The left and right aluminum ladder assemblies are respectively composed of upper and lower assemblies connected by pins on their fixing seats. Both the upper and lower assemblies are supported by left and right main tubes supporting the plastic steps, with reinforcing tubes at the ends. A reinforcing central main tube is located in the middle of the plastic steps. The upper end of the upper assembly has a connecting seat for connecting with objects at higher positions, fixed by a bottom strip. The lower end of the lower assembly has an upper bridge plate for contacting the ground, connected by a rear bottom plate. The aluminum ladder is lightweight, easy to fold and carry, and the two aluminum ladder assemblies are connected as a single unit, providing strong integrity and easy movement. It has sufficient load-bearing capacity and is very convenient to use. Essentially, it is still a metal step; the plastic parts are only for comfort and anti-slip purposes, with the main function provided by the aluminum metal.

[0010] CN216684787U discloses a composite material plastic treadle, including a frame, a panel on the top of the frame, ribs installed at the bottom of the panel, anti-slip texture on the top of the panel, a heat-absorbing pipe installed inside the ribs, a heat-absorbing block inside the heat-absorbing pipe, an air inlet pipe installed at one end of the heat-absorbing pipe, and an air outlet pipe installed at the other end. This composite material plastic treadle, by incorporating a frame, panel, ribs, permeable holes, anti-slip texture, and combining an air inlet pipe, heat-absorbing pipe, and heat-absorbing block, can improve the stability and safety of the composite material plastic treadle, prevent the tread from freezing and slipping, reduce operating costs, and minimize resource waste. Its novel structural design and relatively stable performance not only ensure the tread's service life but also benefit environmental protection. However, this composite material plastic treadle is not suitable for applications requiring frequent movement or complex environments, such as telescopic ladders.

[0011] CN202689519U discloses an anti-slip tread, including a board body and friction patterns on the upper surface of the board body. The board body has several through holes, and the two ends of the board body are provided with positioning steps that can be spliced. The positioning steps are provided with positioning through holes for positioning. The friction patterns are protrusions on the upper surface of the board body. It has the following features: (1) The tread has a conspicuous reminder mark; (2) The tread has through holes for easy installation and disassembly; (3) The two ends of the tread have splicing positioning steps and positioning through holes, which can connect multiple treads into a whole, effectively preventing the tread from sliding on the scaffold; (4) The tread is lightweight and uses reinforcing ribs with rounded corners to improve the mechanical strength of the tread; (5) The tread is made of glass fiber reinforced polypropylene material, which has high mechanical strength and anti-slip effect, long service life and other characteristics. Wooden and bamboo treads are prone to rotting and deterioration when used outdoors for extended periods, resulting in poor mechanical properties and a short lifespan. Ordinary plastic treads are limited in mechanical strength and cannot withstand significant pressure, and their surface friction is relatively weak. Although iron treads have good mechanical properties, they are prone to rust, are heavy, easily deformed, and inconvenient to use. In actual construction, workers often use haphazardly assembled simple treads, which are prone to slipping and pose a significant safety hazard. However, this technology is specifically designed for scaffolding construction, consisting of multiple small, immovable modules assembled into a large template. Therefore, it is not suitable for applications requiring frequent relocation or complex environments where the mechanical properties of telescopic ladders are not adequately considered.

[0012] In summary, to overcome the inherent defects of aluminum alloy and stainless steel treads for telescopic ladders, and the fact that conventional designs of polymer materials cannot meet the requirements of telescopic ladder treads, in order to expand production capacity and assembly efficiency and significantly reduce overall costs, we have researched a set of integral polymer tread structure technology specifically for telescopic ladder treads. Summary of the Invention

[0013] The purpose of this utility model is to overcome the above-mentioned problems existing in the prior art and provide a special integral polymer pedal structure for telescopic ladders. This utility model overcomes the inherent defects of aluminum alloy pedals and stainless steel pedals in the field of telescopic ladders, as well as the defects that conventional polymer materials cannot meet the stringent requirements of telescopic ladder pedals, and achieves the purpose of expanding production capacity and assembly efficiency, and significantly reducing overall costs.

[0014] To achieve the above-mentioned technical objectives and effects, this utility model is implemented through the following technical solution:

[0015] An integral polymer tread structure for telescopic ladders includes a tread body, comprising a central tread and sleeves on either side of the tread that can connect to telescopic columns. The tread and sleeves are molded from polymer material into an inseparable whole using molding technology. The tread and sleeves are smoothly connected by a process radius (R-angle). The tread has a step surface, two side surfaces, and a process bottom surface. The sleeves have a hoop and a hoop hole. The step surface has anti-slip protrusions and concave surfaces and wear-resistant ribs. The process bottom surface has reinforcing ribs and anti-deformation components.

[0016] Preferably, when the distance between the two sides of the pedal is approximately the same as the outer diameter of the sleeve, the connection process radius (R) is zero; when the distance between the two sides of the pedal is greater than or less than the outer diameter of the sleeve, the connection process radius (R) is greater than or equal to 0.5 mm.

[0017] Preferably, the stepping surface is 10-150 cm long, 5-30 cm wide, 2-15 cm high, and 0.2-5.5 mm thick. The polymer material is PE, PP, ABS, or PA, and 0-50% calcium carbonate or glass fiber reinforcement can be added.

[0018] Preferably, the anti-slip protrusions and depressions include lateral and longitudinal protrusions or depressions, which are used to prevent the foot from slipping laterally or longitudinally when people step on the pedal and generate lateral force, thus avoiding instability and falls.

[0019] Preferably, the wear-resistant ribs are divided into primary wear-resistant ribs and secondary wear-resistant ribs. The primary wear-resistant ribs are ribs that protrude from the plane, and the secondary wear-resistant ribs are planes with depressions or grooves around the perimeter. The primary and secondary wear-resistant ribs are distributed at intervals, so that even after the primary wear-resistant ribs are worn out, the sole of the foot can still contact the secondary wear-resistant ribs to continue to provide anti-slip and wear-resistant functions.

[0020] Preferably, the reinforcing ribs include unidirectional reinforcing ribs and cross reinforcing ribs. The cross-section of the reinforcing ribs is a triangle or trapezoid with rounded corners. The maximum thickness of the ribs is less than 10 mm, and the minimum thickness of the ribs is greater than 0.5 mm.

[0021] Preferably, the anti-deformation combination is composed of a cross combination of anti-deformation metal inserts or reinforcing ribs.

[0022] Preferably, the hoop covers the telescopic column, and its projection along the direction of the telescopic column is a circle, ellipse, polygon, approximately polygonal, multi-pointed star, or any combination of petals.

[0023] Preferably, the hoop hole and the telescopic column are loosely fitted, and the hole diameter is more than 0.1 mm larger than the outer diameter of the telescopic column. The hoop hole is uniformly provided with more than one deformable interference fit rib, which facilitates the fitting of the telescopic column and eliminates looseness caused by gaps in the hoop hole.

[0024] Preferably, the two side surfaces are provided with decorative textures and / or external decorative assembly process with raised and recessed perforations, which alters the appearance and surface quality.

[0025] The beneficial effects of this utility model are:

[0026] (1) It overcomes the inherent defects of aluminum alloy and stainless steel treads in the field of telescopic ladders, as well as the defects that conventional polymer materials cannot meet the stringent requirements of telescopic ladder treads. It has a wide range of applications, fast molding speed, fast assembly speed, and good weather resistance and deformation resistance.

[0027] (2) Anti-slip and wear-resistant, with various reinforcement methods, including pre-installation and post-installation, strong resistance to damage, and significantly extended service life;

[0028] (3) Compared with the current aluminum alloy pedals and stainless steel pedals, the shape and structure can be simple or complex, the design freedom is high, the mass production cost is low, and the economic benefits are significant.

[0029] (4) It is more environmentally friendly, avoids pollution, and can be recycled many times.

[0030] The above description is merely an overview of the technical solution of this utility model. To better understand the technical means of this utility model and to enable its implementation according to the description, the following detailed description uses preferred embodiments of this utility model in conjunction with the accompanying drawings. Specific implementation methods of this utility model are given in detail in the following embodiments and their accompanying drawings. Attached Figure Description

[0031] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0032] Figure 1 is a schematic diagram of the assembly relationship between the integral polymer pedal and the telescopic column of this utility model;

[0033] Figure 2 is a bottom view of an embodiment of the present invention: an integral polymer pedal.

[0034] Figure 3 is a schematic cross-sectional view of an embodiment of the present invention, showing an integral polymer pedal.

[0035] Figure 4 is a schematic diagram of the assembly relationship between the pedal hoop and the telescopic column in one embodiment of this utility model;

[0036] Figure 5 is a schematic diagram of the distribution of multiple wear-resistant structures in one embodiment of the present invention;

[0037] Figure 6 is a partially enlarged schematic diagram of the back of the hoop position in an embodiment of this utility model;

[0038] Figure 7 is a partially enlarged front view of the hoop position in an embodiment of this utility model;

[0039] Figure 8 is a front view of the assembled finished product according to an embodiment of the present invention;

[0040] Figure 9 is a top view of the assembled finished product according to an embodiment of this utility model.

[0041] The following are the labels in the diagram: 1. Pedal; 2. Sleeve; 3. Telescopic column; 11. Step surface; 12. Side surfaces; 13. Process bottom surface; 21. Hoop; 22. Hoop hole; 23. Anti-loosening rib; 111. Anti-slip protrusions and depressions; 112. Wear-resistant rib; 131. Reinforcing rib; 132. Anti-deformation combination; 1121. First-grade wear-resistant rib; 1122. Second-grade wear-resistant rib; 1123. Recess or groove. Embodiments of the present invention

[0042] The present invention will be further described below with reference to the accompanying drawings:

[0043] Referring to Figures 1 to 9, a special integral polymer step structure for telescopic ladders includes a step body. The step body includes a central step and sleeves 2 on both sides of the step 1 that can be connected to telescopic columns 3. The step 1 and sleeves 2 are molded from polymer material into an inseparable whole using molding technology. The step 1 and sleeves 2 are smoothly connected by a process radius. The step 1 is provided with a step surface 11, two side surfaces 12, and a process bottom surface 13. The sleeves 2 are provided with a hoop 21 and a hoop hole 22. The step surface 11 is provided with anti-slip protrusions and grooves 111 and wear-resistant ribs 112. The process bottom surface 13 is provided with reinforcing ribs 131 and anti-deformation assembly 132.

[0044] Preferably, when the distance between the two side surfaces 12 of the pedal 1 is approximately the outer diameter of the sleeve 2, the connection process R angle is zero; when the distance between the two side surfaces 12 of the pedal 1 is greater than or less than the outer diameter of the sleeve 2, the connection process R angle is 0.5 mm or more.

[0045] Preferably, the step surface 11 is 10-150 cm long, 5-30 cm wide, 2-15 cm high, and 0.2-5.5 mm thick. The polymer material is PE, PP, ABS, or PA, and 0-50% calcium carbonate or glass fiber reinforcement can be added. In general scenarios, a step surface with a length of 30-60 cm, a width of 10-20 cm, a height of 5-10 cm, a wall thickness of 1.5-2.5 mm, and PP or PA polymer material with 15-30% calcium carbonate or glass fiber reinforcement is the optimal choice.

[0046] Preferably, the anti-slip protrusions and depressions 111 include lateral and longitudinal protrusions or depressions, which are used to prevent the foot from slipping laterally or longitudinally when people step on the pedal and generate lateral force, thus avoiding instability and falling.

[0047] Preferably, the wear-resistant ribs 112 are divided into primary wear-resistant ribs and secondary wear-resistant ribs. The primary wear-resistant ribs are ribs that protrude from the plane, and the secondary wear-resistant ribs are planes with depressions or grooves around the perimeter. The primary and secondary wear-resistant ribs are distributed at intervals, so that even after the primary wear-resistant ribs are worn out, the sole of the foot can still contact the secondary wear-resistant ribs to continue to provide anti-slip and wear-resistant functions.

[0048] Preferably, the reinforcing rib 131 includes unidirectional reinforcing ribs and cross reinforcing ribs. The cross-section of the reinforcing rib is a triangle or trapezoid with rounded corners. The maximum thickness of the rib is less than 10 mm, and the minimum thickness of the rib is greater than 0.5 mm. The optimal combination is that the maximum thickness of the rib is less than 5 mm and the minimum thickness of the rib is greater than 1.5 mm. This can effectively avoid shrinkage pits caused by uneven thickness and can fully and quickly fill the mold, avoiding scorching caused by missing ribs or poor local venting.

[0049] Preferably, the anti-deformation assembly 132 is composed of a cross combination of anti-deformation metal inserts or reinforcing ribs 131. In situations where heavy loads are frequently required, anti-deformation metal inserts should be the optimal solution.

[0050] Preferably, the hoop 21 covers the telescopic column 3, and its projection along the direction of the telescopic column is a circle, ellipse, polygon, approximately polygon, multi-pointed star, or any combination of petals, etc., which increases the freedom of the telescopic ladder's appearance design and beautifies the product's appearance.

[0051] Preferably, the hoop hole 22 and the telescopic column 3 are loosely fitted, and the hole diameter is more than 0.1 mm larger than the outer diameter of the telescopic column to facilitate easy assembly and insertion. The hoop hole is evenly provided with more than 3 deformable interference fit ribs to facilitate the insertion of the telescopic column 3. The interference compression deformation of the ribs eliminates the looseness caused by the gap in the hoop hole, which is also known as anti-loosening rib.

[0052] Preferably, the two side surfaces 12 are provided with decorative textures and / or external decorative assembly process convex and concave holes, which can change the appearance shape and surface quality. Because it is molded using polymer materials, it is easy to achieve surface molding of various appearance shapes by carving molds, which greatly improves the designer's freedom of appearance design.

[0053] This invention has a wide range of applications and can be used in almost any scenario where a pedal is needed and the pedal length is less than 1.5 meters. It is suitable for both static and dynamic loads, as well as light and heavy load applications. It can produce pedals with a simple structure and appearance at low cost, as well as pedals with a very complex and beautiful craft-grade appearance at low cost. The disadvantage is that it cannot be adapted to small-batch special customization. The structural design requires rich experience and a lot of experimentation. It cannot be designed and formed arbitrarily. The advantage is that the production cost is very low when mass-producing, the molding speed is very fast, and the quality and stability are extremely high. The effect is even better if the pedal is soaked in hot water and slowly cooled to relieve stress after molding.

[0054] The above description is only a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model.

Claims

1. A whole polymer ladder special footboard structure, comprising a footboard body, the footboard body comprising a footboard in the middle and sleeves (2) capable of being connected with telescopic columns (3) on both sides of the footboard (1), characterized in that: The pedal (1) and sleeve (2) are formed into an inseparable whole by high polymer material through molding technology, the pedal (1) and sleeve (2) are smoothly connected through process R angle, the pedal (1) is provided with a tread surface (11), two side surfaces (12) and a process bottom surface (13), the sleeve (2) is provided with a hoop (21) and a hoop hole (22), the tread surface (11) is provided with anti-skid convex and concave (111) and wear-resistant rib (112), the process bottom surface (13) is provided with a reinforcing rib (131) and an anti-deformation combination (132).

2. The integral polymer step-plate structure for extension ladder according to claim 1, wherein: When the distance of the two side surfaces (12) of the pedal (1) is approximately equal to the outer diameter of the sleeve (2), the connected process R angle is zero, when the distance of the two side surfaces (12) of the pedal (1) is greater than or less than the outer diameter of the sleeve (2), the connected process R angle is greater than or equal to 0.5mm.

3. The integral polymer step-plate structure for extension ladder according to claim 2, wherein: The tread surface (11) is 10-150CM long, 5-30CM wide, 2-15CM high, and 0.2-5.5mm thick, the high polymer material is PE, PP, ABS or PA, and 0-50% calcium carbonate or glass fiber can be added.

4. The integral polymer step-plate structure for extension ladder according to claim 1, wherein: The anti-skid convex and concave (111) includes transverse and longitudinal convex or concave, which is used to prevent the lateral force when people step on the pedal, to avoid the palm slipping along the transverse or longitudinal direction, resulting in unstable center of gravity and falling.

5. The integral polymer step-plate structure for extension ladder according to claim 1, wherein: The wear-resistant rib (112) is divided into a first-level wear-resistant rib (1121) and a second-level wear-resistant rib (1122), the first-level wear-resistant rib is a convex flat rib, the second-level wear-resistant rib is a flat surface with a concave or groove (1123) around, the first-level wear-resistant rib and the second-level wear-resistant rib are distributed at intervals, so that the palm can still contact the second-level wear-resistant rib to continue to provide the function of anti-skid and wear-resistant after the first-level wear-resistant rib is worn out.

6. The integral polymer step-plate structure for extension ladder according to claim 1, wherein: The reinforcing rib (131) includes a one-way reinforcing rib and a cross reinforcing rib, the cross section of the reinforcing rib is a triangular or trapezoidal shape with rounded corners, the maximum thickness of the rib is less than 10mm, and the minimum thickness of the rib is greater than 0.5mm.

7. The integral polymer step board structure for extension ladder according to claim 1, wherein: The anti-deformation combination (132) is composed of an anti-deformation metal insert or a cross combination of reinforcing ribs (131).

8. The integral polymer step board structure for extension ladder according to claim 1, wherein: The hoop (21) wraps and covers the telescopic column (3), and the projection in the telescopic column direction is circular, oval, polygonal, approximately polygonal, multi-angle star-shaped or any petal combination shape.

9. The integral polymer step board structure for extension ladder according to claim 1, wherein: The hoop hole (22) is loosely matched with the telescopic column (3), the hole diameter is greater than the outer diameter of the matched telescopic column by more than 0.1mm, and the hoop hole is uniformly provided with more than three deformable interference fitting ribs, which facilitates the sleeving and clamping of the telescopic column (3) and eliminates the looseness of the hoop hole due to the gap.

10. The integral polymer step board structure for extension ladder according to claim 1, wherein: The two side surfaces (12) are provided with decorative texture and / or external decorative combination process convex and concave hole column, which changes the appearance shape and surface quality.

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