A cement board production device, a vacuum-extruded cement board and a manufacturing method thereof

Abstract

The application provides a cement board production equipment, a vacuum extrusion forming cement board and a manufacturing method thereof, and belongs to the field of buildings. The application designs multiple threaded forming mandrels with adjustable spacing, and makes reserved prestressed hole and thread-shaped grooves on the inner wall of the reserved prestressed hole on the plate body through the threaded forming mandrels. Meanwhile, prestressed reinforcement is arranged in the reserved prestressed hole, and high-strength mortar is grouted in the reserved prestressed hole. The prestress is transmitted along the whole length and anchored in the plate body through the bonding force between the prestressed reinforcement and the high-strength mortar and the mechanical interlocking force between the high-strength mortar and the prefabricated groove. The quantitative evaluation model of the introduced cross-sectional stress uniformity λ and the pressure level coefficient κ is used to determine the optimal prestressed reinforcement spacing with λ >= 0.95 as the control condition. After the prestressed reinforcement is tensioned, the high-strength mortar is grouted into the hole, and after solidification reaches the designed strength, the prestressed reinforcement is cut off, which can effectively improve the tensile strength and ductility of the vacuum extrusion forming plate and has a wide application range.

Description

Technical Field

[0001] This application relates to the field of construction, and more particularly to a cement board production equipment, a vacuum extrusion cement board, and a method for manufacturing the same. Background Technology

[0002] Currently, vacuum extruded composite panels (ECPs) are widely used in building envelope systems due to their excellent molding process and dimensional accuracy. However, due to the brittle nature of cement-based materials, their tensile strength is low, and they are prone to cracking under tensile stress, which affects the overall structural performance. This limits their use to non-load-bearing components and severely restricts their application scenarios.

[0003] To improve the load-bearing capacity of ECP slabs, introducing prestressing technology is one effective approach. However, traditional post-tensioned prestressing technology relies on permanent mechanical anchors to anchor prestressing tendons at the ends of the member, which has the following drawbacks: First, mechanical anchors increase material costs and the complexity of construction procedures; second, stress concentration occurs in the anchor area, easily inducing splitting failure of the end concrete; third, the cross-sectional dimensions of extruded slabs are small, making it difficult to place conventional anchors at the ends; fourth, traditional extrusion processes make it difficult to directly embed tensioning reinforcement during molding, and pre-tensioning methods cannot be directly applied. These problems prevent traditional prestressing technology from being directly applied to the production and application of ECP slabs. Summary of the Invention

[0004] One of the purposes of this application is to provide a vacuum extrusion molded cement board, which aims to solve the technical problem that existing ECP boards have low tensile strength and limited application scenarios due to the inability to apply prestress.

[0005] The second objective of this application is to provide a method for manufacturing vacuum extrusion-molded cement boards, which aims to provide a method for applying prestress without relying on permanent mechanical anchors, by bonding and transmitting force with high-strength mortar through the threaded grooves on the inner wall of the pre-reserved prestressed duct.

[0006] The technical solution of this application is: A cement board production equipment includes a frame, a forming head assembly, and a tensioning mechanism; the forming head assembly and the tensioning mechanism are respectively disposed on the frame; the forming head assembly extrudes and forms a slab blank from a mixed material used for vacuum extrusion molding of cement boards; the tensioning mechanism is used to tension the slab blank by threading reinforcing bars. The forming head assembly includes a conical forming shell. A forming guide rail that can move axially is installed between the large end of the conical forming shell and its two inner walls. The forming guide rail is connected to a plurality of threaded forming mandrels with adjustable spacing. The threaded forming mandrels are composed of threaded sections and smooth cylindrical sections arranged alternately along the axial direction. A shaping shell with a hollow interior and an open free end is provided on the outer side of the small end of the conical forming shell. The ends of the threaded forming mandrels extend into the shaping shell. A surface forming groove is provided on the inner wall of the shaping shell, and a forming core block is provided in the inner cavity. The forming core block and the threaded forming mandrels in the shaping shell are spaced apart.

[0007] As a further technical solution of this application, the tensioning mechanism has a support frame mounted on the machine frame. A first crossbeam, a tensioning platform, a rear crossbeam, a hydraulic jack, and a second crossbeam are sequentially arranged along the axial direction on the support frame. A front crossbeam, a first movable crossbeam, and a second movable crossbeam are sequentially arranged on the upper surface of the tensioning platform, all parallel to and spaced from the first crossbeam. The first crossbeam, the front crossbeam, and the first movable crossbeam are connected by a first screw rod. The hydraulic jack is located at the rear crossbeam, and its driving end is connected to the second crossbeam for driving the second crossbeam to move. The second crossbeam is connected to one end of a second screw rod, and the other end of the second screw rod passes through the rear crossbeam and connects to the second movable crossbeam, for driving the second movable crossbeam to move on the tensioning platform to tension the prestressing tendons in the vacuum extruded cement board.

[0008] A vacuum extrusion-molded cement board, manufactured using the cement board production equipment described above, includes a board body; the board body has multiple pre-formed cavities and reserved prestressed channels extending longitudinally through its interior; the inner wall of the reserved prestressed channels has pre-formed grooves integrally formed by an extrusion molding process; prestressed tendons are inserted into the reserved prestressed channels, and high-strength mortar is poured into the reserved prestressed channels.

[0009] As a further technical solution of this application, the plurality of prefabricated cavities are arranged in parallel intervals along the transverse direction of the plate body, and the plurality of reserved prestressed channels are arranged in parallel intervals along the transverse direction of the plate body.

[0010] As a further technical solution of this application, the pre-made groove is a threaded groove, and is integrally formed by a threaded forming mandrel pressing on the inner wall of the reserved prestressed channel during the extrusion process.

[0011] A method for manufacturing a vacuum extruded cement board as described in any of the preceding claims includes the following steps: S1, Determine the optimal channel spacing sParameter settings are used to construct a stress effect evaluation model and determine the optimal duct spacing between the prestressing tendons. s ; S2, Extrusion molding: Based on the optimal channel spacing s Adjust the molding head assembly, mix various toughening fibers and cement-based raw materials according to the mixing ratio requirements, and extrude them to form a slab with pre-made cavities and reserved prestressed channels. After cutting and curing, a hardened slab is obtained. S3, Tensioning: Position the hardened slab on the tensioning mechanism, pass the prestressed tendons through the reserved prestressed ducts, and tension the prestressed tendons to the design control stress and then hold and lock them. S4, Pressure grouting and curing: Under the load-bearing state, high-strength mortar is pressure-injected into the reserved prestressed ducts to ensure that the reserved prestressed ducts are densely filled, and cured until the high-strength mortar reaches the design strength. S5, Tension Release and Quality Inspection: After the high-strength mortar reaches the required strength, tension is released, excess prestressing tendons at the ends of the slab are cut off to form the slab body, and then inspection is carried out.

[0012] As a further technical solution of this application, in step S1, the construction of the stress effect evaluation model includes the following steps: Input key parameters into the stress effect expression, including the effective prestress. N The width of the plate body L The height of the plate body d ; The initial spacing between the prestressing tendons is preset. s 1; Calculate the stress distribution across the cross-section of the plate body; The stress uniformity λ and pressure level coefficient k of the cross section of the plate body are calculated based on the obtained stress distribution of the cross section of the plate body. The stress distribution of the cross section of the plate body under this initial channel spacing is evaluated based on the stress uniformity λ and pressure level coefficient k. If λ ≥ 0.95, then the design requirements are met, and the optimal spacing between the prestressing tendons is determined. s If λ < 95, it indicates that the design requirements are not met. This can be addressed by changing the initial channel spacing. s 1. Iterate until the design requirements are met, and determine the optimal prestressed duct spacing. s .

[0013] As a further technical solution of this application, the stress distribution of the plate body across its cross section is obtained through the following stress effect expression: ; In the formula: The stress distribution across the cross-section of the plate body; N To ensure effective pre-stressing; L It is half the width of the plate body; t The thickness of the plate body; n The order of the Fourier series; x These are the position coordinates along the lateral direction of the plate body; d It is half the length of the plate body; s The spacing between the prestressing tendons; y The coordinates are the position coordinates along the longitudinal direction of the plate body.

[0014] As a further technical solution of this application, the cross-sectional stress uniformity λ and the cross-sectional pressure level coefficient κ are calculated using the following formulas respectively: ; ; In the formula: ( x=0 The normal stress is located at the midpoint of two adjacent prestressed ducts on the cross-section of the plate body. ( x =s The stress at the prestressing tendon on the cross-section of the plate body is the normal stress. ( x The normal stress distribution on the cross-section of the plate body is shown in the figure. The average normal stress is denoted as σ.

[0015] As a further technical solution of this application, in step S3, multiple standard-sized slab blanks are spliced ​​together longitudinally, and the continuous prestressing tendons are passed through the spliced ​​reserved prestressing ducts and then tensioned as a whole.

[0016] The beneficial effects of this application are: (1) This application provides a cement board production equipment, which installs a forming guide rail that can reciprocate along its axial direction between the two inner walls of the large end of the cone-shaped forming shell, and connects one end of a plurality of parallel spaced threaded forming mandrels with adjustable spacing, extends the other end of the threaded forming mandrel into the forming shell, and sets a surface forming groove on the inner wall of the forming shell, and sets a forming core block in the inner cavity. At the same time, the threaded forming mandrel adopts a segmented structure, which is composed of threaded segments and smooth cylindrical segments arranged alternately along its axial direction, thereby enabling the creation of reserved prestressed channels and threaded grooves on the inner wall of the board body. The threaded grooves can be integrally pressed by the threaded forming mandrel and the inner wall of the reserved prestressed channels during the extrusion forming stage of vacuum extrusion forming cement board, so that the mechanical properties of the vacuum extrusion forming cement board produced are significantly improved.

[0017] (2) This application provides a vacuum extrusion molded cement board, which fills high-strength mortar into a reserved prestressed channel with a threaded groove. The mechanical interlocking force and bonding force transfer mechanism between the reserved prestressed channel and the high-strength mortar filled later are utilized by the geometric structure of the reserved prestressed channel. This eliminates the permanent mechanical anchors required by the traditional post-tensioning method, eliminates the risk of end stress concentration, and realizes an innovative prestressing application method of post-tensioned member-pre-tensioning mechanism. It significantly improves the mechanical properties of the vacuum extrusion molded cement board, broadens its application scenarios, effectively overcomes the technical defects of low tensile strength and weak ductility of traditional vacuum extruded plates, and significantly improves the crack resistance and ultimate bearing capacity of the vacuum extrusion molded cement board, enabling it to meet the application requirements of high-performance load-bearing components such as sidewalk slabs and bridge decks.

[0018] (3) This application provides a method for manufacturing a vacuum extrusion-molded cement board, which first constructs a stress effect evaluation model, inputs key parameters into the stress effect expression, and presets the initial channel spacing between prestressing tendons. s 1. Calculate the cross-sectional stress uniformity λ and cross-sectional pressure level coefficient k of the slab body based on the obtained cross-sectional stress distribution. Determine the optimal spacing between prestressing tendons based on the obtained λ. sThen, using a specially designed threaded mandrel, pre-stressed channels with threaded grooves on the inner wall are simultaneously constructed during the vacuum extrusion molding of the sheet. After the sheet hardens, prestressing tendons are inserted and tensioned. Subsequently, high-strength mortar is injected into the pre-stressed channels under pressure. After the mortar solidifies, the tension is released. The prestressing tendons are uniformly transmitted along the entire length of the pre-stressed channels and anchored in the sheet body through the bonding force between them and the high-strength mortar, as well as the mechanical interlocking force between the high-strength mortar and the threaded grooves on the inner wall of the pre-stressed channels. This method does not require permanent mechanical anchors, and the manufacturing method adopts a post-tensioning process in terms of component manufacturing. In terms of prestress transmission mechanism, it simulates the full-length bonded force transmission mechanism of the pre-tensioning method, thereby upgrading the ECP into a high-performance load-bearing component that can withstand active loads. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the cement board production equipment provided in the first embodiment of this application; Figure 2 This is a schematic diagram of the tensioning mechanism provided in the first embodiment of this application; Figure 3 This is a schematic diagram of the molding head assembly provided in the first embodiment of this application; Figure 4 This is a schematic diagram of the first angle of the molding head assembly provided in the first embodiment of this application.

[0021] Figure 5 This is a schematic diagram of the vacuum extrusion-molded cement board structure provided in the second embodiment of this application; Figure 6 This is a schematic diagram of the first angle structure of the vacuum extrusion-molded cement board provided in the second embodiment of this application; Figure 7 This is a partially enlarged schematic diagram of the vacuum extrusion-molded cement board provided in the second embodiment of this application; Figure 8 This is a schematic diagram of the process for manufacturing a vacuum extrusion-molded cement board according to the third embodiment of this application.

[0022] Icons: 1-Material conveying mechanism; 2-Vacuum extrusion feed hopper; 3-Frame; 4-Vacuum extrusion main unit; 5-Forming die head assembly; 6-Receiving and transmission mechanism; 7-Automatic length cutting mechanism; 8-Tensioning mechanism; 9-Conical forming shell; 10-Forming guide rail; 11-Threaded forming mandrel; 12-Forming shell; 13-Surface forming groove; 14-Forming core block; 15-Support frame; 16-First crossbeam; 17-Tensioning platform; 18-Rear crossbeam; 19-Hydraulic jack; 20-Second crossbeam; 21-Front crossbeam; 22-First movable crossbeam; 23-Second movable crossbeam; 24-First screw rod; 25-Second screw rod; 26-Plate body; 27-Prestressed tendon; 28-High-strength mortar; 29-Precast cavity; 30-Reserved prestressed channel; 31-Precast groove; 32-Toughening fiber; 33-Anchor. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this application, it should be noted that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only used to facilitate the description of this application and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0027] Furthermore, in this application, unless otherwise expressly specified and limited, "above or below" the first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Moreover, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] First embodiment: Please refer to Figure 1 (Refer to) Figures 2 to 4This embodiment provides a cement board production equipment, which mainly includes a material conveying mechanism 1, a vacuum extrusion feed hopper 2, a frame 3, a vacuum extrusion main unit 4, a forming die head assembly 5, a receiving and transmitting mechanism 6, an automatic length-cutting mechanism 7, and a tensioning mechanism 8; wherein, the vacuum extrusion main unit 4, the forming die head assembly 5, the automatic length-cutting mechanism 7, and the tensioning mechanism 8 are sequentially arranged on the frame 3, the receiving and transmitting mechanism 6 is arranged on the frame 3 along the axial direction of the frame 3, and the automatic length-cutting mechanism 7 and the tensioning mechanism 8 are located above the receiving and transmitting mechanism 6 and are arranged perpendicular to the axial direction of the frame 3; the discharge end of the material conveying mechanism 1 is connected to the vacuum extrusion feed hopper 2, and the vacuum extrusion feed hopper 2 is located above one end of the frame 3; the vacuum... The extrusion host 4 and the forming head assembly 5 are both installed on one end of the frame 3. The vacuum extrusion host 4 is located directly below the vacuum extrusion feed hopper 2 and is connected to the discharge end of the vacuum extrusion feed hopper 2. The vacuum extrusion host 4 and the forming head assembly 5 are connected by multiple bolts and are used to extrude and form the mixed material through the forming head assembly 5. The receiving and conveying mechanism 6 is set on the frame 3 along the length direction of the frame 3 and is used to transport the slab body made by the forming head assembly 5. The automatic length-cutting mechanism 7 is set on the frame 3 and above the receiving and conveying mechanism 6 and is used to cut the slab body. The tensioning mechanism 8 is set above the receiving and conveying mechanism 6 and is used to tension the slab body by threading the reinforcing bars.

[0031] It should be noted that in this embodiment, the material conveying mechanism 1, vacuum extrusion feed hopper 2, frame 3, vacuum extrusion host 4, receiving and transmission mechanism 6, and automatic length cutting mechanism 7 all adopt the structure of existing cement board production equipment. Their specific structural design and working principle will not be described in detail here.

[0032] Furthermore, the forming head assembly 5 is installed at the end of the discharge port of the vacuum extrusion host 4. It includes a hollow conical forming shell 9. The large end of the conical forming shell 9 is connected to the end of the discharge port of the vacuum extrusion host 4 by multiple bolts. A forming guide rail 10, capable of reciprocating along its axial direction, is installed between the two opposing inner walls of its large end. That is, the forming guide rail 10 can reciprocate from its large end to its small end. Multiple parallel, spaced, and adjustable threaded forming mandrels 11 are connected to the forming guide rail 10 by bolts. When adjusting the spacing between two adjacent threaded forming mandrels 11, the bolts are removed, and then the spacing between the two adjacent threaded forming mandrels 11 is adjusted. The threaded forming mandrels 11 adopt a segmented structure. Composed of alternating threaded sections and smooth cylindrical sections along its axis, the threaded forming mandrel 11 is used to create the pre-stressed channel 30 and the threaded groove on its inner wall. The threaded groove is integrally formed by the threaded forming mandrel 11 and the inner wall of the pre-stressed channel 30 during the extrusion molding stage of vacuum extrusion molding of cement board. A shaping shell 12 with a hollow interior and an open free end is provided on the outer side of the small end of the cone-shaped shaping shell 9. One end of the threaded forming mandrel 11 is connected to the forming guide rail 10, and the other end extends into the inner cavity of the shaping shell 12. A surface forming groove 13 is provided on the inner wall of the shaping shell 12, and a forming core block 14 for creating the pre-formed cavity 29 is provided in the upper region of the inner cavity of the shaping shell 12. The forming core block 14 is located above the threaded forming mandrel 11. The forming guide rail 10 can reciprocate back and forth. When the forming guide rail 10 moves forward, it extrudes and forms a prestressed channel with a threaded groove. Conversely, it extrudes and forms a smooth cylindrical prestressed channel.

[0033] Its tensioning mechanism 8 has a support frame 15 arranged perpendicular to the axis of the frame 3. A first crossbeam 16, a tensioning platform 17, a rear crossbeam 18, a hydraulic jack 19, and a second crossbeam 20 are sequentially arranged along the axis on the support frame 15. On the upper surface of the tensioning platform 17, a front crossbeam 21, a first movable crossbeam 22, and a second movable crossbeam 23 are sequentially arranged, all parallel to and spaced from the first crossbeam 16. The first crossbeam 16, the front crossbeam 21, and the first movable crossbeam 22 are connected by a first screw rod 24. The hydraulic jack 19 is mounted on the rear crossbeam 18, and its drive end is connected to the second crossbeam 20 for driving the second crossbeam. The second crossbeam 20 makes a slight linear movement; one end of the second screw rod 25 is connected to the second crossbeam 20, and the other end passes through the rear crossbeam 18 and the second movable crossbeam 23 in sequence and is connected to the second movable crossbeam 23. The prestressed tendon 27 is fixed to the first movable crossbeam 22 and the second movable crossbeam 23 by the anchor 33. When the second crossbeam 20 makes a slight linear movement, it can drive the second screw rod 25 to make a slight linear movement, thereby driving the second movable crossbeam 23 connected to it to make a slight linear movement, thereby synchronously tensioning the prestressed tendon 27 to the design control stress and then holding the load.

[0034] The cured slab body 26 is transferred to the tensioning platform 17 and positioned between the first movable beam 22 and the second movable beam 23. The prestressing tendon 27 passes sequentially through the first movable beam 22, the slab body 26, and the second movable beam 23, with both ends connected to the first movable beam 22 and the second movable beam 23 respectively. After the prestressing tendon 27 is inserted into the slab body 26, the hydraulic jack 19 is activated. The hydraulic jack 19 drives the connected second screw rod 25 to make a slight linear movement. The second screw rod 25 drives the connected second movable beam 23 to make a slight linear movement on the tensioning platform 17, and the second movable beam 23 then drives the prestressing tendon 27 to be tensioned. Thus, the second screw rod 25 and the hydraulic jack 19 are used to synchronously tension the prestressing tendon 27 to the design control stress and then hold the load. According to actual engineering requirements, multiple standard-sized slab bodies 26 can be longitudinally spliced ​​and tensioned as a whole through the same prestressing tendon 27.

[0035] A tension release device is installed between the tensioning platform 17 and the rear crossbeam 18. This device utilizes existing technology, and its specific structure and working principle will not be detailed here. Its function is to smoothly unload the tensioning system after the prestressing tendons 27 have been anchored or the mortar has reached the specified strength. During the tension holding stage, it replaces the hydraulic jack 19 in bearing and locking the tension force. During the tension release stage, it can release this mechanical lock, providing conditions for the controlled return movement of the first movable crossbeam 22 and the second movable crossbeam 23. When the tension release device is working, it can control the first movable crossbeam 22 and the second movable crossbeam 23 to slowly return to their original positions, preventing sudden release of the prestressing tendons 27 that could cause cracking of the slab, end breakage, or impact damage to the tensioning equipment.

[0036] It should be noted that in this embodiment, single-end tensioning is used, that is, only one hydraulic jack 19 is used to tension the prestressing tendon 27 at one end. When the hydraulic jack 19 tensions the prestressing tendon 27 at one end, the first screw rod 24, which is connected to one end of the prestressing tendon 27, is anchored and fixed by the first crossbeam 16. The hydraulic jack 19, which is connected to the other end of the prestressing tendon 27, drives the second movable crossbeam 23 to move slightly, thereby stretching the prestressing tendon 27. When the tension of the prestressing tendon 27 reaches the design tension force, the tension is achieved through the first screw rod 24, the first movable crossbeam 22, the second movable crossbeam 23, and the second screw rod 24. 5. The first crossbeam 16 locks the prestressing tendon 27, keeping it in a tensioned state. Then, high-strength mortar 28 is poured into the pre-reserved prestressing duct 30, anchorage zone, and precast groove 31. After the high-strength mortar 28 hardens, it reliably bonds the prestressing tendon 27 to the slab body 26, allowing the tension in the prestressing tendon 27 to be gradually transferred to the slab body 26 through the mortar and slab interface, thereby forming compressive stress within the slab body 26 and improving the slab's bending load-bearing capacity, crack resistance, and overall stiffness. In other embodiments, double-end tensioning can also be used to tension the prestressing tendon 27. Hydraulic jacks 19 are installed at both ends of the prestressing tendon 27, with one hydraulic jack 19 connected to the first crossbeam 16 and the other hydraulic jack 19 connected to the second crossbeam 20, thus tensioning both ends of the prestressing tendon 27 respectively.

[0037] It should be noted that the tensioning mechanism 8 in this embodiment is a tensioning device used to tension the prestressing tendons 27 after they are inserted into the precast slab, based on the principle of post-tensioning. The tensioning platform 17, as the basic load-bearing component of the entire tensioning system, is arranged along the length of the slab body 26; the slab body 26 is placed on the tensioning platform 17. A front crossbeam 21 and a rear crossbeam 18 are respectively provided at both ends of the tensioning platform 17. After the front crossbeam 21 and the rear crossbeam 18 are connected to the tensioning platform 17, they form an overall frame for bearing the tension reaction force. Generally, the tensioning platform 17, the front crossbeam 21, and the rear crossbeam 18 are fixed load-bearing components, which provide a stable installation reference and support for tensioning reaction force. A first movable crossbeam 22 and a second movable crossbeam 23 are respectively set on the outer side or end area of ​​the front crossbeam 21 and the rear crossbeam 18. The first movable crossbeam 22 is connected to the first screw rod 24, and the second movable crossbeam 23 is connected to the second screw rod 25. The first screw rod 24 and the second screw rod 25 are both arranged along the tensioning direction and form an adjustable tension frame structure with the corresponding first movable crossbeam 22 and second movable crossbeam 23. The first screw rod 24 and the second screw rod 25 can be used to adjust the position of the first movable crossbeam 22 and the second movable crossbeam 23, and can also be used for mechanical locking and limiting after tensioning. The first movable crossbeam 22 and the second movable crossbeam 23 are not completely fixed relative to the tensioning platform 17. Under the action of the hydraulic jack 19, they can undergo slight displacement along the length of the plate body 26, thereby causing the prestressing tendons 27 connected to or clamped with them to stretch. In this embodiment, the hydraulic jack 19 can be a horizontal hydraulic jack. After the hydraulic jack 19 is activated, its piston rod extends, generating axial thrust. This force is transmitted through the second movable crossbeam 23 to the second screw rod 25 and the clamping end of the prestressing tendon 27, thereby causing the prestressing tendon 27 to move along its length and undergo tensile deformation.

[0038] The process involves installing a forming guide rail 10, which can reciprocate along its axial direction, between the two inner walls of the cone-shaped forming shell 9. The forming guide rail 10 is connected to one end of multiple parallel, spaced, and adjustable threaded forming mandrels 11. The other end of the threaded forming mandrels 11 extends into the shaping shell 12. A surface forming groove 13 is provided on the inner wall of the shaping shell 12, and a forming core block 14 is provided in the inner cavity. The threaded forming mandrel 11 is constructed in a segmented manner, consisting of alternating threaded segments and smooth cylindrical segments along its axial direction. This allows for the creation of pre-stressed channels 30 and threaded grooves on the inner wall of the plate body 26. The threaded grooves are integrally formed by the threaded forming mandrel 11 and the inner wall of the pre-stressed channels 30 during the extrusion molding stage of the vacuum extrusion molded cement board, resulting in a significant improvement in the mechanical properties of the vacuum extrusion molded cement board.

[0039] Second embodiment: Please refer to Figure 5 (Refer to) Figures 6 to 7 This embodiment provides a vacuum extrusion-molded cement board, aiming to solve the technical problem of low tensile strength and limited application scenarios of existing ECP boards due to the inability to apply prestress. It includes a board body 26, with multiple pre-fabricated cavities 29 and reserved prestressing channels 30 longitudinally extending inside the board body 26. The multiple pre-fabricated cavities 29 are arranged parallel to each other transversely along the board body 26 to save materials and reduce the overall weight of the board. The inner wall of the reserved prestressing channels 30 is provided with pre-fabricated grooves 31, which are threaded... The grooved surface is integrally formed by the threaded mandrel 11 and the inner wall of the pre-stressed channel 30 during the extrusion molding stage of the vacuum extrusion molding of the cement board. Furthermore, the threaded mandrel 11 adopts a segmented structure, consisting of threaded segments and smooth cylindrical segments arranged alternately along its axial direction. Correspondingly, the inner wall of the pre-stressed channel 30 forms a partitioned structure in which threaded grooved segments and smooth hole wall segments are alternately distributed along the longitudinal direction. Prestressed tendons 27 are inserted into the pre-stressed channel, and the pre-stressed channel is densely filled with high-strength mortar 28.

[0040] It should be noted that in this embodiment, the two ends of the prestressing tendon 27 have no exposed permanent mechanical anchors, and the prestressing tendon 27 is prestressed by post-tensioning. After the high-strength mortar 28 in the slab body 26 reaches the design strength, the prestressing tendon 27 is cut at the end of the slab body 26, so that the prestress is reliably transmitted and anchored in the slab body 26 only through the bonding force between the prestressing tendon 27 and / or the high-strength mortar 28. Therefore, the two ends of the prestressing tendon 27 are free cut sections without permanent mechanical anchors, and its prestress is transmitted and anchored in the vacuum extruded cement board along the reserved prestressing channel 30 only by the bonding force between the prestressing tendon 27 and the high-strength mortar 28, and the mechanical interlocking force between the high-strength mortar 28 and the precast groove 31.

[0041] Therefore, this application provides a vacuum extruded cement board, which fills high-strength mortar 28 into a pre-reserved prestressed channel 30 with a threaded groove. Utilizing the geometric structure of the pre-reserved prestressed channel 30 and the subsequent filling of high-strength mortar 28, the mechanical interlocking force and bonding force transfer mechanism between the pre-reserved prestressed channel 30 and the subsequently filled high-strength mortar 28 are eliminated. This eliminates the permanent mechanical anchors required by the traditional post-tensioning method, removes the risk of end stress concentration, and realizes an innovative prestressing application method of post-tensioned components with a pre-tensioning mechanism. It significantly improves the mechanical properties of the vacuum extruded cement board, broadens its application scenarios, effectively overcomes the technical defects of low tensile strength and weak ductility of traditional vacuum extruded sheets, and significantly improves the crack resistance and ultimate bearing capacity of the vacuum extruded cement board, enabling it to meet the application requirements of high-performance load-bearing components such as sidewalk slabs and bridge decks.

[0042] Third embodiment: Please refer to Figure 8 This embodiment provides a method for manufacturing a vacuum extrusion-molded cement board, which is a method of applying prestress without relying on permanent mechanical anchors, and through the bonding force between the high-strength mortar 28 and the grooves in the inner wall of the duct. The method mainly includes the following steps: S1, Determine the optimal channel spacing s : Set parameters, construct a stress effect evaluation model, and determine the optimal duct spacing between prestressing tendons 27. s The construction of the stress effect assessment model includes the following steps: Input key parameters into the stress effect expression, including the effective prestress. N , board width of 26 L The height of the board body is 26. d ; Preset initial duct spacing between prestressed tendons 27 s 1; The stress distribution across the cross section of plate body 26 is obtained using the following stress effect expression: ; In the formula: The stress distribution across the cross section of plate body 26; N To ensure effective pre-stressing; L It is half the width of the 26-plate body; t The thickness of the plate body is 26. n The order of the Fourier series; x These are the position coordinates along the transverse direction of the plate body 26; d It is half the length of the plate body 26; s The spacing between the prestressing tendons 27; y These are the position coordinates along the longitudinal direction of the plate body 26; The stress uniformity λ and the pressure level coefficient k of the cross section of the plate body 26 are calculated by the obtained stress distribution of the cross section of the plate body 26 and the following formula. The stress distribution of the cross section of the plate body 26 under this initial channel spacing is evaluated based on the stress uniformity λ and the pressure level coefficient k. ; ; In the formula: ( x=0 The normal stress is located at the midpoint of two adjacent prestressed ducts on the cross-section of the plate body 26. ( x= s The stress at the prestressing tendon 27 on the cross section of the slab body 26 is the normal stress. ( xThe normal stress distribution is shown in section 26 of the plate body. The average normal stress on the cross section of plate body 26; If λ ≥ 0.95, then the design requirements are met, and the spacing between the prestressing tendons 27 is determined as the optimal spacing between them. s If λ < 95, it indicates that the design requirements are not met. The initial channel spacing can be adjusted accordingly. s 1. Iterate until the design requirements are met, and determine the spacing of the prestressing ducts at this point as the optimal spacing between the prestressing tendons 27. s ; S2, Extrusion molding: Based on the optimal channel spacing s Adjust the forming head assembly 5 in the cement board production equipment, especially by sliding the forming guide rail 10 to adjust the spacing between the thread forming mandrels 11. At the same time, mix various toughening fibers 32 with cement-based raw materials according to the mixing ratio requirements and extrude them to form a slab body with pre-made cavities 29 and reserved prestressed channels 30 inside. After cutting and curing, a hardened slab body is obtained. S3, Tensioning: The hardened slab is positioned on the tensioning platform 17 of the tensioning mechanism 8 in the cement board production equipment. The prestressed tendons 27 are passed through the reserved prestressed ducts 30. The prestressed tendons 27 are tensioned to the design control stress and then held and locked. Multiple standard-sized slabs are spliced ​​together longitudinally, and the continuous prestressed tendons 27 are passed through the reserved prestressed ducts 30 after splicing and then tensioned as a whole. S4, Pressure grouting and curing: Under the load-bearing state, high-strength mortar 28 is pressure-injected into the reserved prestressed duct 30 to ensure that the reserved prestressed duct 30 is densely filled, and cured until the high-strength mortar 28 reaches the design strength. S5, Tension Release and Quality Inspection: After the high-strength mortar 28 reaches the required strength, release the tension, cut off the excess prestressing tendons 27 at the ends of the slab to form the slab body 26, and then inspect it.

[0043] It should be noted that, in this embodiment, the cross-section of the plate body 26 refers to its cross-section on the xoy plane.

[0044] It should be noted that in step S2, the mixture of toughening fiber 32 and cement-based material is mixed in the conveying mechanism 1 and then transported to the vacuum extrusion feed hopper 2, and then enters the vacuum extrusion host 4 through the vacuum extrusion feed hopper 2; according to the optimal channel spacing between the prestressing tendons 27 calculated in step S1... s The relative positions of the internal components of the forming head assembly 5 are precisely adjusted, especially the lateral spacing between two adjacent thread forming mandrels 11 on the forming guide rail 10. This lateral spacing is the optimal channel spacing. sThe vacuum extrusion host 4 is started, driving the forming head assembly 5 to perform forming and extrusion operations on the mixed raw materials. The cavity forming core block 14, the threaded forming core rod 11, and the forming guide rail 10 in the forming head assembly 5 reciprocate to simultaneously extrude a slab with a pre-made cavity 29 and a reserved prestressed channel 30 with a threaded groove on the inner wall. The extruded slab is cut by the automatic length cutting mechanism 7 and sent to the corresponding area for curing until hardened. The cured slab is transferred to the tensioning mechanism 8. After the prestressed tendon 27 is inserted into the tensioning mechanism 8, the prestressed tendon 27 is tensioned to the design control stress and then held and locked by using the large screw rod and hydraulic jack 19 on the tensioning mechanism 8.

[0045] It should be noted that in step S1, the optimal channel spacing is determined. s The principle is as follows: based on the prestressing blind zone range formed by the stress diffusion angle at the end of the prestressing tendon 27, and with the stress uniformity λ of the section not being less than 0.95 as the control condition, the allowable optimal duct spacing is calculated. s This serves as the design basis for adjusting the forming head assembly 5 in step S1; whereby, the stress diffusion angle refers to the angle between the boundary of the effective force transmission area and the longitudinal axis of the plate body 26 when the prestress diffuses and is transmitted from the anchor point to the interior of the cross section along the longitudinal direction of the plate body 26.

[0046] It should be noted that in step S3, according to actual engineering requirements, multiple standard-sized slabs can be longitudinally spliced ​​together and tensioned as a whole through the same prestressing tendon 27.

[0047] Therefore, this application provides a method for manufacturing vacuum extruded cement boards, which proposes an innovative technical approach of post-tensioning components and pre-tensioning mechanisms: it first constructs a stress effect evaluation model to determine the optimal spacing between the prestressing tendons 27. s Then, using a specially designed threaded mandrel 11, a pre-reserved prestressed channel 30 with a threaded groove on the inner wall is simultaneously constructed during the vacuum extrusion molding of the plate body 26. After the plate body hardens, the prestressing tendon 27 is inserted and tensioned. Then, high-strength mortar 28 is injected into the pre-reserved prestressed channel 30 under pressure. After the mortar solidifies, the tension is released. The prestressing tendon 27 is uniformly transmitted along the entire length of the pre-reserved prestressed channel 30 and anchored in the plate body 26 through the bonding force between it and the high-strength mortar 28, and the mechanical interlocking force between the high-strength mortar 28 and the threaded groove on the inner wall of the pre-reserved prestressed channel 30. This method does not require permanent mechanical anchors, and the manufacturing method adopts a post-tensioning process in the component manufacturing method and simulates the full-length bond force transmission mechanism of the pre-tensioning method in terms of prestress transmission mechanism, thereby upgrading the ECP into a high-performance load-bearing component that can withstand active loads.

[0048] In summary, this application combines the construction convenience of post-tensioning with the full-length bonded force transfer mechanism of pre-tensioning by simultaneously prefabricating pre-stressed ducts 30 with threaded grooves during vacuum extrusion molding. This achieves efficient and uniform prestressing of vacuum-extruded sheet materials without requiring permanent mechanical anchors, significantly improving the tensile strength and ductility of the materials. Furthermore, by introducing a quantitative evaluation model of cross-sectional stress uniformity λ and pressure level coefficient κ, the spacing of the prestressing tendons 27 is scientifically and parametrically designed, ensuring the uniformity of prestress distribution and structural safety. After prestressing, the vacuum-extruded sheet materials can be used as high-performance load-bearing components such as sidewalk slabs and bridge decks, effectively expanding the engineering application scope of ECP products.

[0049] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A cement board production equipment, characterized in that, The system includes a frame, a forming head assembly, and a tensioning mechanism; the forming head assembly and the tensioning mechanism are respectively mounted on the frame; the forming head assembly extrudes the mixed material used for vacuum extrusion molding of cement board to form a slab blank; the tensioning mechanism is used to tension the slab blank by threading reinforcing bars. The forming head assembly includes a conical forming shell. A forming guide rail that can move axially is installed between the large end of the conical forming shell and its two inner walls. The forming guide rail is connected to a plurality of threaded forming mandrels with adjustable spacing. The threaded forming mandrels are composed of threaded sections and smooth cylindrical sections arranged alternately along the axial direction. A shaping shell with a hollow interior and an open free end is provided on the outer side of the small end of the conical forming shell. The ends of the threaded forming mandrels extend into the shaping shell. A surface forming groove is provided on the inner wall of the shaping shell, and a forming core block is provided in the inner cavity. The forming core block and the threaded forming mandrels in the shaping shell are spaced apart.

2. The cement board production equipment according to claim 1, characterized in that, The tensioning mechanism has a support frame mounted on the machine frame. Along the axial direction, the support frame is sequentially arranged a first crossbeam, a tensioning platform, a rear crossbeam, a hydraulic jack, and a second crossbeam. On the upper surface of the tensioning platform, a front crossbeam, a first movable crossbeam, and a second movable crossbeam are sequentially arranged, all parallel to and spaced from the first crossbeam. The first crossbeam, the front crossbeam, and the first movable crossbeam are connected by a first screw rod. The hydraulic jack is located at the rear crossbeam, and its driving end is connected to the second crossbeam for driving the second crossbeam to move. The second crossbeam is connected to one end of a second screw rod, and the other end of the second screw rod passes through the rear crossbeam and connects to the second movable crossbeam, for driving the second movable crossbeam to move on the tensioning platform to tension the prestressing tendons in the vacuum-extruded cement board.

3. A vacuum extrusion-molded cement board, manufactured using the cement board production equipment described in claim 1, characterized in that, The slab body includes a slab body; the slab body has multiple prefabricated cavities and reserved prestressed channels that are opened through it longitudinally; the inner wall of the reserved prestressed channel has a prefabricated groove formed integrally by an extrusion molding process; the reserved prestressed channel is filled with prestressed tendons and high-strength mortar.

4. The vacuum extrusion-molded cement board according to claim 3, characterized in that, The prefabricated cavities are arranged in parallel intervals along the transverse direction of the plate body, and the reserved prestressed channels are arranged in parallel intervals along the transverse direction of the plate body.

5. The vacuum extrusion-molded cement board according to claim 3, characterized in that, The pre-formed groove is a threaded groove, which is integrally pressed into the inner wall of the reserved prestressed channel by a threaded forming mandrel during the extrusion process.

6. A method for manufacturing a vacuum extrusion-molded cement board as described in any one of claims 3 to 5, characterized in that, Includes the following steps: S1, Determine the optimal channel spacing s Parameter settings are used to construct a stress effect evaluation model and determine the optimal duct spacing between the prestressing tendons. s ; S2, Extrusion molding: Based on the optimal channel spacing s Adjust the molding head assembly, mix various toughening fibers and cement-based raw materials according to the mixing ratio requirements, and extrude them to form a slab with pre-made cavities and reserved prestressed channels. After cutting and curing, a hardened slab is obtained. S3, Tensioning: Position the hardened slab on the tensioning mechanism, pass the prestressed tendons through the reserved prestressed ducts, and tension the prestressed tendons to the design control stress and then hold and lock them. S4, Pressure grouting and curing: Under the load-bearing state, high-strength mortar is pressure-injected into the reserved prestressed ducts to ensure that the reserved prestressed ducts are densely filled, and cured until the high-strength mortar reaches the design strength. S5, Tension Release and Quality Inspection: After the high-strength mortar reaches the required strength, tension is released, excess prestressing tendons at the ends of the slab are cut off to form the slab body, and then inspection is carried out.

7. The method for manufacturing a vacuum extruded cement board according to claim 6, characterized in that, In step S1, the construction of the stress effect assessment model includes the following steps: Input key parameters into the stress effect expression, including the effective prestress. N The width of the plate body L The height of the plate body d ; The initial spacing between the prestressing tendons is preset. s 1; Calculate the stress distribution across the cross-section of the plate body; The stress uniformity λ and pressure level coefficient k of the cross section of the plate body are calculated based on the obtained stress distribution of the cross section of the plate body. The stress distribution of the cross section of the plate body under this initial channel spacing is evaluated based on the stress uniformity λ and pressure level coefficient k. If λ ≥ 0.95, then the design requirements are met, and the optimal spacing between the prestressing tendons is determined. s If λ < 95, it indicates that the design requirements are not met. This can be addressed by changing the initial channel spacing. s 1. Iterate until the design requirements are met, and determine the optimal prestressed duct spacing. s .

8. The method for manufacturing a vacuum extruded cement board according to claim 7, characterized in that, The stress distribution across the cross-section of the plate body is obtained using the following stress effect expression: ； In the formula: The stress distribution across the cross-section of the plate body; N To ensure effective pre-stressing; L It is half the width of the plate body; t The thickness of the plate body; n The order of the Fourier series; x These are the position coordinates along the lateral direction of the plate body; d It is half the length of the plate body; s The spacing between the prestressing tendons; y The coordinates are the position coordinates along the longitudinal direction of the plate body.

9. The method for manufacturing a vacuum extruded cement board according to claim 7, characterized in that, The stress uniformity λ and the pressure level coefficient κ of the cross section are calculated using the following formulas respectively: ； ； In the formula: ( x=0 The normal stress is located at the midpoint of two adjacent prestressed ducts on the cross-section of the plate body. ( x=s The stress at the prestressing tendon on the cross-section of the plate body is the normal stress. ( x The normal stress distribution on the cross-section of the plate body is shown in the figure. The average normal stress is denoted as σ.

10. The method for manufacturing cement board by vacuum extrusion molding according to claim 6, characterized in that, In step S3, multiple standard-sized slab blanks are spliced ​​together longitudinally, and the continuous prestressing tendons are passed through the pre-reserved prestressing ducts after splicing and then tensioned as a whole.

Images