Half-round bamboo flattening device

Abstract

This invention provides a semi-circular bamboo flattening device, which can continuously flatten a semi-circular whole bamboo in one operation, resulting in high work efficiency, no bamboo cracking, and improved bamboo utilization. It includes a frame, a gradient worktable, a radial pressing device, a tangential pressing device, and a conveying system. The feed end of the gradient worktable is semi-circular, gradually flattening towards the discharge end until the discharge end is completely flat. The conveying system includes multiple pairs of rollers and a conveying drive device. Multiple openings are provided on the worktable from front (feed section) to back (discharge section), with a pair of rollers positioned above and below each opening. The radial pressing device includes an arc-shaped pressure ring and multiple rotating small pressure rollers mounted on the pressure ring. The gap between the small pressure rollers and the opposite upper surface of the worktable is no greater than the thickness of the bamboo. The tangential pressing device applies pressure to the thickness surfaces on both sides of the bamboo along the tangential direction of the bamboo's arc, working together with the worktable to achieve circumferential pressing of the arc-shaped bamboo.

Description

Technical Field

[0001] This invention relates to the field of bamboo strip flattening technology, specifically a semi-circular bamboo flattening device. Background Technology

[0002] Longitudinal flattening of semi-circular bamboo strips is a common method to obtain long, wide, and flat bamboo. Continuous flattening is a frequently used method. Existing continuous methods involve making incisions of a certain depth on the bamboo's outer surface to loosen it, and then rolling the bamboo along its length on both the outer and inner surfaces to flatten it. However, these incisions need to be removed during subsequent processing, resulting in significant waste, increased complexity in the process and equipment, and low bamboo utilization. Some methods, such as CN1820917A, do not involve incisions on the outer surface and instead flatten the bamboo directly. These methods first process the bamboo to a certain length, remove inner nodes, and then roll it laterally. However, this method still results in bamboo with a significant curvature after flattening, requiring further pressing, which can easily lead to cracking. Furthermore, the length is limited, and it cannot flatten the entire bamboo strip. Summary of the Invention

[0003] This invention provides a semi-circular bamboo flattening device, which can continuously flatten a whole semi-circular bamboo in one operation without being limited by the length of the bamboo. It has high work efficiency and the flattened bamboo strips do not crack, thus improving the utilization rate of bamboo.

[0004] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0005] The semi-circular bamboo flattening device includes a frame, a gradually changing worktable on the frame, a radial pressing device, a tangential pressing device, and a conveying system.

[0006] The workbench is gradient-shaped, with a semi-circular arc at the front end (feed end) and gradually flattening towards the rear end (discharge end) until the discharge end is completely flat. The conveying system for driving the bamboo to move forward includes multiple pairs of rollers and a conveying drive device that drives the upper or lower rollers to rotate. Each pair of rollers includes an upper roller and a lower roller. Multiple openings are set on the workbench from front to back, and a pair of rollers is set at the top and bottom of each opening. The convex surface (bamboo green surface) of the bamboo is in contact with the upper surface of the workbench, and the bamboo passes between the upper and lower rollers in each pair of rollers and is pressed by the upper and lower rollers. The rotation of the upper and lower rollers drives the bamboo to move forward.

[0007] Multiple radial pressure devices are installed above the workbench from front to back. The radial pressure devices include an arc-shaped pressure ring and multiple small pressure rollers rotatably mounted on the pressure ring. The gap between the small pressure rollers and the upper surface of the opposite workbench is no greater than the thickness of the bamboo.

[0008] Multiple tangential pressure devices are symmetrically arranged on both sides of the workbench from front to back. The symmetrical tangential pressure devices act on the thickness surface of the bamboo on both sides, applying pressure to the bamboo along the tangential direction of the bamboo arc, and together with the workbench, they achieve circumferential pressure on the curved surface of the bamboo.

[0009] As an improvement, in the conveying device, the outer circumference of the lower roller is a concave arc surface along its rolling axis, and the outer circumference of the upper roller is a convex arc surface along its rolling axis. The concave arc surface of the lower roller is flush with the arc surface of the upper surface of the worktable. From the feeding end to the discharging end, in each pair of rollers, the generatrix length of the concave arc surface of the lower roller and the generatrix length of the convex arc surface of the upper roller gradually increase.

[0010] As an improvement, the lower roller in the conveying device is provided with a groove on its concave arc surface, and the groove extends in the same direction as the rolling axis of the lower roller.

[0011] As an improvement, the lengths of each opening and each pair of rollers increase progressively along the rolling axis of the rollers from front to back on the worktable surface. The upper roller is the drive roller connected to the conveying drive device and is made of heat-resistant rubber or plastic.

[0012] As an improvement, an elastic element is installed between the pressure ring and the frame. Under normal conditions, the elastic element causes the pressure ring to move closer to the worktable, and the small pressure rollers press the bamboo tightly onto the worktable.

[0013] As an improvement, the same pressure ring is made up of multiple pressure roller shafts connected together, and each pressure roller shaft is equipped with a rotating small pressure roller; the two ends of each small pressure roller shaft are respectively hinged to a pressure rod, and an elastic element is set between each pressure rod and the frame. Under normal conditions, the elastic element makes each pressure rod and pressure roller shaft approach the worktable surface, and each small pressure roller presses the bamboo material tightly on the worktable surface, thereby realizing the unfolding of the curved surface of the bamboo material.

[0014] As an improvement, the arc surfaces on the upper surface of each pressure ring and the worktable surface opposite to that pressure ring are concentric circles.

[0015] As an improvement, the tangential pressing device includes a hydraulic cylinder hinged to the frame and a side pressure roller. The side pressure roller is rotatably mounted on the piston rod end extending from the hydraulic cylinder. The side pressure roller is coaxial with the piston rod, and its end face contacts the thickness surfaces on both sides of the bamboo. The radius of the side pressure roller is not less than the thickness of the bamboo. The outer circumferential surface of the side pressure roller contacts the upper surface of the worktable, and the portion of the side pressure roller's end face near the upper surface of the worktable contacts the thickness surfaces on both sides of the bamboo.

[0016] As an improvement, the tangential pressing device includes a hydraulic cylinder two and a side pressure roller two hinged to the frame. A rotatable side pressure roller two is provided at the end of the piston rod two extending from the hydraulic cylinder two (for example, a bracket two is fixed at the end of the piston rod two, the shaft of the side pressure roller two is fixed on the bracket two, and the side pressure roller two is rotatably mounted on the shaft of the side pressure roller two); the outer periphery of the side pressure roller two contacts the thickness surfaces on both sides of the bamboo material, and the rotation axis of the side pressure roller two is perpendicular to the axis of the bamboo material.

[0017] As an improvement, the tangential pressing device also includes an oil pressure detection device for detecting the hydraulic oil pressure in the hydraulic cylinder and the second hydraulic cylinder. When the side pressure roller and the second side pressure roller come into contact with the thickness surfaces on both sides of the bamboo and apply pressure, the hydraulic oil pressure remains unchanged.

[0018] As an improvement, a photoelectric detection device is also included, located in front of each tangential pressing device, for detecting the chord height of the semi-circular bamboo material about to enter the worktable of the tangential pressing device. The photoelectric detection device is electrically connected to the controller, which is electrically connected to the hydraulic valve that controls the operation of the hydraulic cylinder and the second hydraulic cylinder. A hydraulic valve is installed on the hydraulic pipeline connected to the hydraulic cylinder and the second hydraulic cylinder. The controller controls the extension and retraction of the piston rod of the hydraulic cylinder and the second piston rod of the second hydraulic cylinder according to the chord height of the semi-circular bamboo material: when the bamboo material has not reached the worktable of the side pressure roller and the second side pressure roller, the piston rod and the second piston rod are in a retracted state and will not hinder the movement of the bamboo material; when the bamboo material reaches the worktable of the side pressure roller and the second side pressure roller, the piston rod and the second piston rod extend, and apply pressure to the thickness surface of the bamboo material through the side pressure roller and the second side pressure roller.

[0019] The beneficial effects of this invention are as follows:

[0020] The semi-circular whole bamboo strip, softened and with the inner nodes removed, is fed into the worktable from the feed end and clamped by a pair of rollers, namely the upper roller and the lower roller, near the feed end. Then, under the action of the conveying system, the bamboo moves from front to back along the worktable. During the movement, under the action of the small pressure roller, the outer arc surface (bamboo green surface) of the bamboo is always in contact with the upper surface of the worktable, and the bamboo is gradually flattened. At the same time, the tangential pressure device applies pressure to the bamboo along the tangential (circumferential) direction of the bamboo arc surface. Because the bamboo's yellow surface is stretched during the pressing and flattening process of the small pressure rollers and rollers, tangential pressure is used to apply pressure to the circumference of the bamboo's arc. This is done by applying pressure along the tangential direction of the bamboo's arc, compressing the bamboo circumferentially. The green surface of the bamboo is compressed more, while the yellow surface is compressed less, preventing the yellow surface of the curved bamboo from cracking due to excessive stretching during the flattening process.

[0021] The worktable has a non-planar structure. One end (the inlet end) is semi-circular, gradually flattening out towards the other end (the outlet end) until it becomes completely flat. Multiple openings are set in the worktable, with a pair of rollers positioned above and below each opening. The lower roller has a concave arc surface in the middle, with grooves on this surface. The grooves run in the same direction as the roller's length (the direction of the rolling axis) to increase friction during bamboo transport. The concave arc surface of the lower roller is flush with the upper arc surface of the worktable. The upper roller is made of heat-resistant rubber or plastic (because softening the semi-circular bamboo involves high temperatures). The rollers at the inlet end are shorter, gradually increasing in length from the inlet end to the outlet end as the bamboo curves flatten (the lengths of the openings on the worktable also increase), to enhance friction on the bamboo and increase pressure on the flattened surface.

[0022] The gap between the small pressure rollers on the pressure ring and the upper surface of the worktable is no greater than the thickness of the bamboo. This allows the curved bamboo to pass through the gap while applying pressure to ensure it adheres to the curved surface of the worktable, thus gradually unfolding the bamboo's curved shape. The curvature of the pressure rings at different positions above the worktable varies, just like the curvature of the worktable itself. However, the curved surfaces of each pressure ring and the corresponding upper surface of the worktable are concentric circles. The small pressure rollers, together with the worktable, restrict the curvature of the bamboo. As the bamboo passes through the gap from the curved end (feeding end) of the worktable to the tail end, it changes with the curvature between the curved surface of the worktable and the small pressure rollers on the pressure ring, eventually being flattened into a planar shape. The pressure rings can apply pressure to different types of bamboo, pressing them against the curved worktable surface as soon as they enter, keeping the bamboo in an unfolded state. Because of the thickness difference in bamboo walls, the smaller end of the bamboo near the tip has a thinner wall, while the larger end of the bamboo near the root has a thicker wall. If the gap distance remains constant, the radial pressure on the bamboo will change with the change in bamboo thickness. It is possible that the thinner-walled bamboo will not be subjected to radial pressure. Therefore, elastic elements such as springs are installed on the radial pressure device to adjust the gap size, so that radial pressure can be applied to the thin-walled bamboo, allowing the thin-walled bamboo to fit well on the changing work surface.

[0023] Bamboo also exhibits taper; the diameter and chord height of a semi-circular bamboo section vary with its length. The arc near the base of the bamboo is longer with a larger chord height, while the arc near the tip is shorter with a smaller chord height. To apply effective tangential force to the side (thickness surface) of the bamboo, hydraulic cylinders and hydraulic cylinder two of the tangential pressurization device are equipped with oil pressure detection and control devices (such as pressure gauges and control valves). When the diameter of the bamboo arc is larger, the extension length of piston rods and piston rod two is shorter, and vice versa. The oil pressure detection and control device senses changes in pressure based on the chord height of the bamboo arc contacted by the side pressure rollers and side pressure roller two, and extends and retracts accordingly, achieving continuous and effective tangential pressure on the bamboo wall.

[0024] The diameters of different bamboo materials vary. When one bamboo material passes through a tangential pressing device, the next bamboo material is about to pass through that device's location. Due to the different diameters of the bamboo materials, the chord height of the semicircular bamboo material varies. To ensure that the next bamboo material can move smoothly to the worktable position where the tangential pressing device is located, the tangential pressing device needs to be able to lift up in advance. Furthermore, after the next bamboo material moves to the worktable position, the tangential pressing device needs to be able to quickly press down to apply pressure to the side (thickness) of the bamboo material. Therefore, a photoelectric detection device is installed in front of the front end of the worktable to detect the chord height of the semicircular bamboo material about to enter the front end of the worktable. The controller controls the extension and retraction of the piston rod of the hydraulic cylinder and the piston rod of the second hydraulic cylinder based on the chord height of the semicircular bamboo material. Photoelectric detection devices are also installed in front of other tangential pressing device positions for the same purpose. Lifting and pressing times are set for each tangential pressing device, so that the tangential pressing devices at different positions can be lifted sequentially and then pressed down quickly.

[0025] Tangential pressing devices are not always applied vertically downwards. The tangential pressing devices at different positions vary with the curvature of the worktable. From the feeding end, they are placed vertically and apply vertical pressure to the bamboo. At the discharge end, they gradually become flat with the curvature of the bamboo strips, and the pressing device is also placed approximately horizontally, applying approximately horizontal pressure to the bamboo.

[0026] The conveying device consists of multiple pairs of rollers arranged in upper and lower sections. The lower rollers are concave in the length direction, with the largest curvature on the concave surface of the lower rollers near the feed end of the worktable. The curvature of the concave surface of the lower rollers gradually flattens from the feed end to the discharge end. The upper rollers are made of rubber or plastic. The gap between the upper and lower rollers is equal to the thickness of the bamboo material. The length of the rollers increases continuously from the feed end to the discharge end.

[0027] This invention enables continuous, crack-free unfolding of semi-circular whole bamboo, improving bamboo utilization and providing a continuous process with high operational efficiency.

[0028] Bamboo softening is a standard technique, and the softening temperature and time are well-known. After softening, the inner nodes of the bamboo are removed so that the bamboo can be smoothly conveyed and moved along the workbench. Attached Figure Description

[0029] Figure 1 This is a front view schematic diagram of a semi-circular bamboo flattening device.

[0030] Figure 2 This is a top view of the semi-circular bamboo flattening device.

[0031] Figure 3 This is a schematic diagram of the worktable surface, tangential pressurization device, etc., at different cross-sections from front to back.

[0032] Figure 4 This is a schematic diagram of the worktable surface, radial pressure device, etc., at different cross-sections from front to back.

[0033] Figure 5 This is a side view of the semi-circular bamboo flattening device (feeding end).

[0034] Figure 6 This is a schematic diagram of a tangential pressure device applying pressure to the thick surface of bamboo.

[0035] In the diagram, the worktable is 1, the feed end is 11, the discharge end is 12, and the opening is 13.

[0036] Radial pressure device 2, pressure ring 21, small pressure roller 22, pressure roller shaft 23, pressure rod 24, spring 25,

[0037] Tangential pressurizing device 3, hydraulic cylinder 31, piston rod 32, side pressure roller 33,

[0038] Conveying system 4, upper roller 41, lower roller 42, conveying drive device 43, lower roller concave arc surface 44,

[0039] 5. Photoelectric limit switch; 6. Frame

[0040] Bamboo material 100, bamboo material thickness surface 101. Detailed Implementation

[0041] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0042] The whole long semi-circular bamboo flattening device of the present invention unfolds the semi-circular bamboo to improve the utilization area and utilization rate of the bamboo. It includes a frame 6, a progressive worktable 1 set on the frame, a radial pressing device 2, a tangential pressing device 3, a conveying system 4, and a photoelectric limit switch 5, etc.

[0043] The front end of the progressive worktable 1, i.e. the feeding end 11, is semi-circular, and as it extends towards the rear end, i.e. the discharging end 12, the arc gradually flattens out until the discharging end is completely flat. Multiple openings 13 are provided in the middle of the worktable from front to back.

[0044] The conveying system 4 for driving the bamboo material to move from front to back includes multiple pairs of rollers and a conveying drive device 43 for driving the upper roller 41 or the lower roller 42 to rotate. Each pair of rollers includes an upper roller and a lower roller; a pair of rollers are arranged vertically at each opening position. The lower roller has a concave arc surface 44 in the middle along its rolling axis (length direction) on its outer periphery, and the concave arc surface of the lower roller is flush with the arc surface of the upper surface of the worktable. The concave arc surface 44 of the lower roller is provided with grooves, and the grooves extend in the same direction as the rolling axis of the lower roller.

[0045] Along the worktable surface from front to back, the lengths of each opening 13 and each pair of rollers (upper roller 41 and lower roller 42) increase in the direction of the roller rolling axis. The upper roller 41 is the drive roller connected to the conveying drive device 43 and is made of heat-resistant rubber or heat-resistant plastic.

[0046] The convex (bamboo green) surface of the softened bamboo 100, after removing the inner nodes, is in contact with the upper surface (concave) of the worktable 1. The bamboo 100 passes between the upper roller 41 and the lower roller 42 in each pair of rollers and is pressed by the upper roller 41 and the lower roller 42. The convex (bamboo green) surface of the bamboo 100 contacts the concave arc surface 44 of the lower roller 42, and the concave (bamboo yellow) surface of the bamboo 100 contacts the convex arc surface of the upper roller 41. In each pair of rollers, the generatrix length of the concave arc surface 44 of the lower roller 42 and the generatrix length of the convex arc surface of the upper roller 41 also varies. The generatrix length near the feeding end is the shortest. As the bamboo moves from the feeding end to the discharging end, the generatrix length of the concave arc surface 44 of the lower roller 42 and the generatrix length of the convex arc surface of the upper roller 41 become longer, and the generatrix length near the discharging end is the longest.

[0047] Multiple radial pressing devices 2 are arranged above the worktable from front to back. Each radial pressing device includes an arc-shaped pressure ring 21, small pressure rollers 22, pressure roller shafts 23, pressing rods 24, and springs 25. The pressure ring 21 is formed by multiple pressure roller shafts 23 connected sequentially, with a rotating small pressure roller 22 mounted on each pressure roller shaft 23; both ends of each pressure roller shaft are hinged to a pressing rod 24. Each pressing rod 24 is slidably connected to the frame 6, and a spring 25 is placed between each pressing rod and the frame. Under normal conditions, the spring 25 causes each pressing rod 24 and pressure roller shaft 23 to move closer to the upper surface of the worktable, and each small pressure roller 22 presses the bamboo material firmly against the upper surface of the worktable. Each pressure ring is essentially arc-shaped, and the arc surface on the upper surface of the worktable opposite to the pressure ring is essentially a concentric circle.

[0048] Multiple tangential pressing devices 3 are symmetrically arranged on both sides of the workbench from front to back. These symmetrical tangential pressing devices act on the thickness surfaces at both ends of the bamboo cross-section arc, applying pressure to the bamboo along the tangential direction of the bamboo arc. The tangential pressing device 3 includes a hydraulic cylinder 31 with its upper end hinged to a frame located on both sides of the workbench, a hydraulic pipeline with hydraulic valves, an oil pressure detection and control device for detecting and controlling the hydraulic oil pressure inside the hydraulic cylinder, and a side pressure roller 33. A rotatable side pressure roller 33 is rotatably mounted at the end of the piston rod 32 extending from the hydraulic cylinder 31. The side pressure roller 33 is coaxial with the piston rod 32, and its radius is not less than the thickness of the bamboo 100. The outer circumferential surface of the side pressure roller contacts the upper surface of the edge of the workbench, and the part of the side pressure roller end face near the upper surface of the workbench contacts the bamboo thickness surface 101 on the side of the bamboo 100.

[0049] Of course, other tangential pressing devices can also be used. For example, another tangential pressing device includes a second hydraulic cylinder hinged at the upper end of the cylinder body to a frame located on both sides of the worktable, hydraulic lines with hydraulic valves, an oil pressure detection and control device for detecting and controlling the hydraulic oil pressure inside the second hydraulic cylinder, and a second side pressure roller. A second bracket is fixed to the end of the piston rod extending from the second hydraulic cylinder, and the shaft of the second side pressure roller is fixed to the second bracket. The second side pressure roller is rotatably mounted on its shaft. The outer periphery of the second side pressure roller contacts the thickness surfaces 101 on both sides of the bamboo material, and the rotation axis of the second side pressure roller is perpendicular to the axis of the bamboo material.

[0050] The photoelectric limit switch 5, serving as a photoelectric detection device, is located at the front end of the workbench and is used to detect the chord height and arrival time of the semi-circular bamboo 100 about to enter the front end of the workbench. The photoelectric limit switch 5 is electrically connected to the controller, which is electrically connected to the hydraulic valve controlling the operation of the hydraulic cylinder and the second hydraulic cylinder. Based on the chord height and arrival time of the semi-circular bamboo, the controller controls the extension and retraction of the piston rod 32 of the hydraulic cylinder 31 and the piston rod 2 of the second hydraulic cylinder: when the bamboo 100 has not reached the workbench surface where the side pressure rollers 33 and 2 are located, the piston rods 32 and 2 are retracted, not hindering the movement of the bamboo; when the bamboo reaches the workbench surface where the side pressure rollers 33 and 2 are located, the piston rods 32 and 2 extend, applying pressure to the thickness surface 101 of the bamboo through the side pressure rollers 33 or 2. When the side pressure rollers 33 or 2 contact and apply pressure to the thickness surfaces on both sides of the bamboo, the hydraulic oil pressure remains constant.

[0051] This invention provides a semi-circular bamboo flattening device, which can continuously flatten a semi-circular whole bamboo stalk in one operation, resulting in high work efficiency, no bamboo cracking, and improved bamboo utilization. It includes a frame, a gradient worktable, radial pressing devices, tangential pressing devices, and a conveying system. The feed end of the gradient worktable is semi-circular, gradually flattening towards the discharge end until the discharge end is completely flat. The conveying system includes multiple pairs of rollers and a conveying drive device. Multiple openings are provided on the worktable from front (feed section) to back (discharge section), with a pair of rollers positioned above and below each opening. Multiple radial pressing devices are arranged above the worktable from front to back, with the pressure rings in the radial pressing devices gradually increasing in size according to the curvature of the worktable. The change also increases from small to large, achieving the flattening of the bamboo's curved surface. The radial pressing device includes an arc-shaped pressure ring and multiple rotating small pressure rollers set on the pressure ring. The gap between the small pressure rollers and the upper surface of the opposite worktable is no greater than the thickness of the bamboo. Multiple symmetrical tangential pressing devices are set on both sides of the gradient worktable from front to back. The tangential pressing devices apply pressure to the thickness surface on both sides of the bamboo along the tangential direction of the bamboo's arc, and together with the worktable, achieve circumferential pressing of the curved bamboo, preventing the bamboo yellow surface from cracking due to uneven stretching at various points of the arc during the flattening process.

[0052] The scope of protection of this invention includes, but is not limited to, the above embodiments. The scope of protection of this invention is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art fall within the scope of protection of this invention.

Claims

1. A semi-circular bamboo flattening device, characterized in that: It includes a frame, a worktable mounted on the frame, a radial pressurizing device, a tangential pressurizing device, and a conveying system; The worktable is gradient-shaped, with a semi-circular arc at the front (feed end) that gradually flattens towards the rear (discharge end) until the discharge end is completely flat. The conveying system for moving softened bamboo (with inner nodes removed) from the feed end to the discharge end includes multiple pairs of rollers on the gradient-shaped worktable and a conveying drive device that drives either the upper or lower rollers. Each pair of rollers includes an upper roller and a lower roller. Multiple openings are provided on the worktable from front to back, with a pair of rollers positioned above and below each opening. The convex surface of the bamboo (the green side) is in contact with the upper surface of the worktable, and the bamboo passes between the upper and lower rollers in each pair and is pressed by them. The purpose of the rollers and conveying drive device is to convey and flatten the semi-circular bamboo during the flattening process. Multiple radial pressure devices are installed above the workbench from front to back. Each radial pressure device includes an arc-shaped pressure ring and multiple rotating small pressure rollers mounted on the pressure ring. The gap between the small pressure rollers and the upper surface of the workbench is no greater than the thickness of the bamboo. The arc of the pressure ring in the radial pressure device also increases with the arc of the workbench. The purpose of setting up the radial pressure device is to make the semi-circular bamboo fit tightly against the workbench and to flatten the arc of the bamboo. Multiple tangential pressing devices are symmetrically arranged on both sides of the workbench from front to back. The symmetrical tangential pressing devices act on the thickness surface of the bamboo on both sides, and press the bamboo along the tangential direction of the bamboo arc, together with the workbench to achieve circumferential pressing of the semi-circular bamboo. The tangential pressing device includes a hydraulic cylinder and a side pressure roller hinged to the frame. A rotating side pressure roller is provided at the end of the piston rod extending out of the hydraulic cylinder. The side pressure roller is coaxial with the piston rod, and the end face of the side pressure roller contacts the thickness surfaces on both sides of the bamboo. The radius of the side pressure roller is greater than the thickness of the bamboo. The outer circumferential surface of the side pressure roller contacts the upper surface of the worktable, and the edge of the end face of the side pressure roller near the upper surface of the worktable contacts the thickness surfaces on both sides of the bamboo. Alternatively, the tangential pressing device includes a hydraulic cylinder two and a side pressure roller two hinged to the frame, with a rotatable side pressure roller two provided at the end of the piston rod two extending out of the hydraulic cylinder two; the outer periphery of the side pressure roller two contacts the thickness surfaces on both sides of the bamboo material, and the rotation axis of the side pressure roller two is perpendicular to the axis of the bamboo material.

2. The semi-circular bamboo flattening device according to claim 1, characterized in that: The outer circumference of the lower roller is a concave arc surface along its rolling axis, while the outer circumference of the upper roller is a convex arc surface along its rolling axis. The concave arc surface of the lower roller is flush with the arc surface on the upper surface of the gradient worktable. From the feed end to the discharge end, in each pair of rollers, the generatrix length of the concave arc surface of the lower roller and the generatrix length of the convex arc surface of the upper roller gradually increase.

3. The semi-circular bamboo flattening device according to claim 1, characterized in that: The lower roller has grooves on its concave surface, and the direction of the grooves is consistent with the direction of the rolling axis of the lower roller.

4. The semi-circular bamboo flattening device according to claim 1, characterized in that: An elastic element is installed between the pressure ring and the frame. Under normal conditions, the elastic element causes the pressure ring to move closer to the worktable, and the small pressure rollers press the curved bamboo material firmly onto the worktable.

5. The semi-circular bamboo flattening device according to claim 1, characterized in that: The same pressure ring is composed of multiple pressure roller shafts connected together, and a small pressure roller is rotatably installed on each pressure roller shaft; both ends of each pressure roller shaft are respectively hinged to a pressure rod, and an elastic element is installed between each pressure rod and the frame. Under normal conditions, the elastic element causes the pressure rods and pressure roller shafts to move closer to the worktable surface, and each small pressure roller presses the bamboo material tightly onto the worktable surface.

6. The semi-circular bamboo flattening device according to claim 1, characterized in that: The arc surfaces on the upper surface of the worktable opposite each pressure ring are concentric circles.

7. The semi-circular bamboo flattening device according to claim 1, characterized in that: The tangential pressing device also includes an oil pressure detection device for detecting the hydraulic oil pressure in the hydraulic cylinder. When the side pressure roller contacts and applies pressure to the thickness surfaces on both sides of the bamboo, the hydraulic oil pressure remains unchanged.

8. The semi-circular bamboo flattening device according to claim 1, characterized in that: It also includes a photoelectric detection device installed in front of each tangential pressing device to detect the chord height of the semi-circular bamboo material about to enter the worktable of the tangential pressing device. The photoelectric detection device is electrically connected to the controller, and the controller is electrically connected to the hydraulic valve that controls the hydraulic cylinder. A hydraulic valve is installed on the hydraulic pipeline connected to the hydraulic cylinder. The controller controls the extension and retraction of the piston rod of the hydraulic cylinder according to the chord height of the semi-circular bamboo material: when the bamboo material has not reached the worktable of the side pressure roller, the tangential pressing piston rod is in a retracted state and will not hinder the movement of the bamboo material; when the bamboo material reaches the worktable of the side pressure roller, the piston rod extends and applies pressure to the thickness surface of the bamboo material through the side pressure roller at the piston rod end, thereby achieving circumferential pressure on the curved bamboo material.

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