Rapid lap joint device and method for fiber reinforced thermoplastic resin composite material ribs

Abstract

The invention discloses a rapid lap joint device and method for fiber reinforced thermoplastic resin composite material ribs, and belongs to the field of material science and engineering. The device comprises a thermoplastic resin sleeve, a lower die, an upper die and the like, the lower die is provided with a positioning hole and a lap joint groove position, the upper die is matched and assembled with a limiting cylinder through a limiting hole, a splitting device, a lap joint diameter adjuster and a lap joint length adjuster can adapt to lap joint of rib materials of different specifications, and a press vulcanizer is used for heating after die assembly. The lap joint method comprises the following steps: splitting and crossing the ribs, sleeving the sleeve, optionally winding the reinforcing layer, and then placing in a mold for heating and compression molding. According to the invention, test pieces under different working conditions can be prepared in batches, and the problems of insufficient pressure, incapability of quantification, difficulty in temperature control and low preparation efficiency existing in manual preparation of lap joint test pieces in the prior art are effectively solved by increasing the shear area, enhancing the strength through winding reinforcement, ensuring alignment of rib materials through limiting bulges at the two ends and meeting multi-parameter preparation through an adjustor.

Description

Technical Field

[0001] The present invention belongs to the field of material science and engineering, and in particular relates to a device and method for quickly splicing fiber-reinforced thermoplastic resin composite reinforcement bars. Background Art

[0002] Fiber-reinforced resin-based composite bars (FRP bars) have been established as an innovative solution to the problem of chloride ion corrosion in civil engineering infrastructure due to their comprehensive performance advantages, including lightweight, high strength, corrosion resistance, and fatigue resistance. They have been used in demonstration projects to replace steel bars in fields such as bridge engineering and marine structures, extending the service life of structures to 2-3 times the original baseline and reducing the overall life cycle cost by about 30%. Current FRP bars are mainly based on thermosetting resins (epoxy resins / unsaturated polyester resins) as the matrix material. The fiber orientation process achieves precise control of specific strength and elastic modulus. As the main and structural bars of concrete structures, they can effectively limit the width of crack expansion. However, due to the inherent characteristics of the three-dimensional cross-linked network of thermosetting resins, their fracture toughness index has significant defects. Microcracks are induced in the strain threshold range of 0.5% to 0.8%. The interfacial debonding effect under the coupled moisture-heat working conditions is exacerbated, which seriously limits the application and expansion of this material in high-end engineering scenarios such as the node areas of super-high-rise buildings.

[0003] In comparison, the thermoplastic resin matrix has a linear or branched molecular chain topology and no chemical cross-linking, so its heat softening-cooling solidification process is a reversible physical phase change, which gives thermoplastic composite reinforcement multiple composite molding characteristics. Compared with thermosetting composite reinforcement, this material system exhibits significant advantages: including but not limited to excellent mechanical properties, outstanding impact strength, efficient molding rate, enhanced toughness and plasticity, recyclability, excellent thermal stability, chemical corrosion resistance and optimized storage adaptability. Based on the technical characteristics of thermoplastic composite reinforcement that can be repeatedly hot-processed and molded, it breaks through the limitations of the traditional factory prefabrication production model and realizes on-demand instant molding at the construction site, significantly improving its compatibility with the dynamic construction needs of the civil engineering field.

[0004] Current composite reinforcement splicing technology is mainly aimed at thermosetting composite reinforcements, with mechanical and adhesive connections being the main methods. The metal sleeves and rivet bolts used in mechanical splicing have disadvantages such as weak corrosion resistance, weak chemical bonding with resin adhesives, and prone to uneven interface penetration during connection. Traditional adhesive splicing mostly uses thermosetting resins such as epoxy resins, which have disadvantages such as long curing cycles, easy aging in hot and humid environments, and weak interface chemical bonding. The thermoplastic composite reinforcement splicing device and splicing method protected by this patent completely uses non-metallic materials to complete the splicing under high temperature and high pressure, effectively promoting the interpenetration of molecular chains at the interface, while using continuous fibers for circumferential constraint reinforcement to further enhance the bearing capacity of the splicing area.

[0005] Currently, existing composite reinforcement splicing devices have drawbacks such as insufficient pressure, inability to quantify, difficulty in controlling temperature, and low production efficiency. Therefore, a rapid splicing device for fiber-reinforced thermoplastic resin composite reinforcement is needed. Summary of the Invention

[0006] In view of the above shortcomings, the present invention provides a rapid splicing device for fiber reinforced thermoplastic resin (FRTP) composite reinforcement bars, which has the ability to efficiently produce splicing specimens with multiple diameters, multiple splicing lengths and diversified reinforcement means.

[0007] The technical solution adopted by the present invention is as follows: a lap joint device for fiber-reinforced thermoplastic resin composite material bars, comprising a thermoplastic resin sleeve, a lower mold, an upper mold, a flat plate vulcanizer, a limiting cylinder, a strand divider, a lap diameter adjuster and a lap length adjuster; the lower mold is provided with a positioning hole for fixing the limiting cylinder, and a plurality of lap slots are set; the upper mold is provided with a limiting hole, which cooperates with the limiting cylinder to realize mold assembly; the strand divider is used to split the fiber-reinforced thermoplastic resin composite material bars, the lap diameter adjuster and the lap length adjuster are used to adjust the size of the lap slot to adapt to the lap of composite material bars of different specifications, and the pretreated composite material bars are placed in the lap slot. After the lower mold and the upper mold are closed, they are placed in a flat plate vulcanizer for heating the composite material bars.

[0008] Furthermore, the slots of the lower mold and the upper mold are designable and combinable. A set of molds can be combined with slots of two to three diameters. By increasing the width and length of the mold, the preparation quantity and overlap length can be increased within the size range of the flat vulcanizer.

[0009] Furthermore, two reinforcement axis positioning pieces are respectively provided at both ends of the slot.

[0010] Furthermore, the strand splitter end includes a blade for cutting the composite reinforcement into predetermined overlap lengths and strand numbers.

[0011] The present invention also provides a method for splicing fiber-reinforced thermoplastic resin composite reinforcement bars based on the above-mentioned device, wherein the splicing section of the composite reinforcement bar to be connected is subjected to a cross-stranding treatment, a thermoplastic resin sleeve is sleeved, and a fiber reinforcement layer is optionally wrapped around it. The pretreated composite reinforcement bar is placed in a mold, heated to the resin softening temperature using a flat vulcanizer, and then compression molded. The splicing interface is formed into a molecular chain interpenetrating structure through hot pressing and fusion, combined with the fiber reinforcement effect, significantly improving the mechanical properties and reliability of the node. Specifically, the method comprises the following steps:

[0012] S1. Insert the limiting cylinder into the positioning hole of the lower mold and weld it in place;

[0013] S2. Adjust the splitter, overlap diameter adjuster, and overlap length adjuster according to the design parameters, and place the pretreated composite reinforcement into the adjustment groove;

[0014] S3. The mold assembly is completed by coordinating the upper mold limit hole and the limit cylinder;

[0015] S4. Place the assembly in the center area of ​​the flat vulcanizing press panel;

[0016] S5. Preheat the flat vulcanizing press to the set temperature;

[0017] S6. Use a strand splitter to split the composite reinforcement into strands in the overlapped area. Cross and overlap the two strands of composite reinforcement bundles, then cover them with thermoplastic resin sleeves. Wrap fiber cloth around the overlapped area as required.

[0018] S7. Place the appropriate overlap diameter adjuster or overlap length adjuster into the corresponding slot in the lower die and insert the pre-treated reinforcement.

[0019] S8. Align the upper die limit hole with the lower die limit cylinder and press the upper die to embed the limit cylinder into the upper die limit hole;

[0020] S9. Place the assembled mold in the middle of the flat vulcanizer, close the mold so that the upper panel lightly contacts the upper mold surface and continue heating;

[0021] S10. After the mold is heated to the set temperature, a predetermined pressure is applied to close the mold and press the overlap area tightly. After maintaining the temperature and pressure for a certain period of time, the temperature is lowered and the pressure is maintained until the resin solidifies.

[0022] S11. After depressurizing and cooling to a set temperature, remove the mold and the composite material reinforcement; lift the upper mold and remove the overlapped fiber-reinforced thermoplastic resin composite material reinforcement.

[0023] Furthermore, the groove diameters of the lower mold and the upper mold are suitable for the maximum overlap diameter including the reinforcing material. When performing overlap without fiber reinforcement or hot pressing overlap without supplementary resin, the overlap cavity diameter is adjusted by overlap diameter adjusters of different thicknesses.

[0024] Furthermore, the overlapping length of the slots provided in the lower die and the upper die is 200 mm. When producing overlapping test pieces with shorter overlapping lengths, overlapping length adjusters with different overlapping cavity lengths and overlapping diameters are used.

[0025] Furthermore, the application of uniform circumferential constraint force and uniform temperature field during the overlapping process is achieved through the numerical control system of the flat vulcanizing machine.

[0026] The present invention has the following advantages and beneficial effects: It enables the batch preparation of specimens with different lap diameters and reinforcement conditions in a single operation; it improves lap strength by increasing the actual shear area of ​​the lap joint, and simultaneously implements circumferential reinforcement with fiber cloth or prepreg tape, significantly enhancing the interface bearing capacity. Symmetrically distributed sheet-like limiting protrusions are provided at both ends of each slot to ensure axial alignment of the reinforcement, optimizing anchor clamping accuracy and mechanical properties; and it is equipped with lap diameter and lap length adjusters to meet the requirements of multiple process parameter preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a three-dimensional schematic diagram of a rapid splicing device for fiber-reinforced thermoplastic resin composite material bars provided by the present invention;

[0028] Figure 2 This is a front view of a quick splicing device for fiber-reinforced thermoplastic resin composite reinforcement provided by the present invention;

[0029] Figure 3 This is a side view of a quick splicing device for fiber-reinforced thermoplastic resin composite reinforcement provided by the present invention;

[0030] Figure 4 It is a three-dimensional schematic diagram of the upper and lower molds and the limiting cylinder provided by the present invention;

[0031] Figure 5 is a three-dimensional schematic diagram of the overlap diameter adjuster provided by the present invention;

[0032] Figure 6 It is a three-dimensional schematic diagram of the overlap length adjuster provided by the present invention;

[0033] Figure 7 It is a three-dimensional schematic diagram of the composite reinforcement strand splitter provided by the present invention;

[0034] Figure 8 1 is a schematic flow chart of the single strand splicing method provided by the present invention;

[0035] Figure 9 It is a schematic flow chart of the double-strand splicing method provided by the present invention;

[0036] Figure 10 1 is a schematic flow chart of the four-strand overlapping method provided by the present invention;

[0037] Explanation of the accompanying symbols: 1-composite material reinforcement; 2-thermoplastic resin sleeve; 3-lower mold; 4-upper mold; 5-flat vulcanizer; 6-limiting cylinder; 7-composite material reinforcement splitter; 8-lap diameter adjuster; 9-lap length adjuster. DETAILED DESCRIPTION

[0038] To better illustrate the purpose, technical solutions, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the claims of the present invention. Unless otherwise specified, the methods in the present invention are all conventional methods.

[0039] Example 1

[0040] A device for splicing fiber-reinforced thermoplastic resin composite reinforcement bars comprises a thermoplastic resin sleeve 2, a lower die 3, an upper die 4, a plate vulcanizer 5, a limiting cylinder 6, a strand splitter 7, a splice diameter adjuster 8, and a splice length adjuster 9. The lower die 3 is provided with a positioning hole for fixing the limiting cylinder 6 and is provided with multiple splice slots. The upper die 4 is provided with a limiting hole that cooperates with the limiting cylinder 6 to achieve mold assembly. The strand splitter 7 is used to split the fiber-reinforced thermoplastic resin composite reinforcement bars. The splice diameter adjuster 8 and the splice length adjuster 9 are used to adjust the size of the splice slots to accommodate splices of reinforcement bars of different specifications. The pretreated composite reinforcement bars 1 are placed in the splice slots. After the lower die 3 and the upper die 4 are closed, they are placed in the plate vulcanizer 5 for heating the composite reinforcement bars 1. The slots of the lower die 3 and the upper die 4 can be combined with two to three diameters. By increasing the width and length of the die, the number of splices and the splice length can be increased within the size range of the plate vulcanizer 5. Two 5mm thick reinforcement axis positioning pieces are provided at both ends of the slot. The end of the strand splitter 7 includes a blade for cutting the composite reinforcement into a predetermined overlap length and number of strands.

[0041] Example 3

[0042] The implementation method of single strand splicing is as follows:

[0043] First, preheat the flat-plate vulcanizer to reach the melting process temperature of the composite reinforcement. Set equal-length thermoplastic resin sleeves in the 200mm interval at the double-reinforcement lap end, and implement fiber cloth circumferential winding reinforcement. According to the preset lap specifications (length 200mm, diameter 23mm), directly match the standard mold cavity for hot pressing molding without the need for additional regulators. Place the pretreated composite reinforcement into the corresponding slot of the lower mold, and through the precise alignment of the upper mold limit hole and the lower mold cylinder, implement mold assembly and apply moderate pressure to ensure that the limit system is fully engaged. Place the module in the hot pressing center area of ​​the flat-plate vulcanizer, start the flat-plate vulcanizer so that the equipment displays the initial pressure value to ensure continuous heat conduction. After the mold as a whole is heated to the set value, apply a constant pressure of 15MPa for 5 minutes to complete the melt penetration. After depressurizing and cooling until the resin is completely solidified, demold and remove the finished product to complete the single-strand lap.

[0044] Example 2

[0045] The implementation method of four-strand overlap is as follows:

[0046] First, preheat the flat-plate vulcanizer to reach the melting temperature of the composite reinforcement. Use a four-strand splitter to split the double reinforcement within a 100mm range. After the split parts are crossed and overlapped, they are circumferentially wrapped with reinforcing fiber cloth and fitted with thermoplastic resin sleeves of equal length. According to the preset overlap specifications (length 100mm, diameter 18mm), a 6mm thick 100mm long overlap length adjuster is pre-placed in the corresponding slot of the lower mold, and then the pretreated reinforcement is placed in the slot. The upper mold limit hole and the lower mold limit cylinder are precisely aligned, and the upper mold is pressed to ensure that the limit system is fully engaged. The assembly module is placed in the hot pressing center area of ​​the flat-plate vulcanizer, and the equipment is started and the mold is closed until the plate surface is slightly pressed against the upper mold. The system displays the initial pressure value to ensure continuous heat conduction. When the mold as a whole is heated to the preset temperature, a constant pressure of 5MPa is applied for 10 minutes to complete the melt penetration and compaction. After the pressure is relieved and cooled until the resin is completely solidified, the overlapped product is demoulded and removed to complete the connection of the four composite reinforcements.

Claims

1. A splicing device for fiber-reinforced thermoplastic resin composite reinforcement, characterized in that: The invention comprises a thermoplastic resin sleeve (2), a lower mold (3), an upper mold (4), a flat vulcanizing machine (5), a limiting cylinder (6), a strand splitter (7), an overlap diameter regulator (8) and an overlap length regulator (9); the lower mold (3) is provided with a positioning hole for fixing the limiting cylinder (6), and a plurality of overlap slots are provided; the upper mold (4) is provided with a limiting hole, which cooperates with the limiting cylinder (6) to realize mold assembly; the strand splitter (7) is used to split the composite material reinforcement (1), the overlap diameter regulator (8) and the overlap length regulator (9) are used to adjust the size of the overlap slot to adapt to the overlap of reinforcement materials of different specifications, and the pre-treated composite material reinforcement (1) is placed in the overlap slot. After the lower mold (3) and the upper mold (4) are closed, they are placed in the flat vulcanizing machine (5) to heat the composite material reinforcement (1).

2. The fiber reinforced thermoplastic resin composite material reinforcement splicing device according to claim 1, characterized in that: The slots of the lower mold (3) and the upper mold (4) can be combined with two to three diameters. By increasing the mold width and length, the preparation quantity and overlap length can be increased within the size range of the flat vulcanizer (5).

3. The fiber reinforced thermoplastic resin composite material reinforcement splicing device according to claim 1, characterized in that: Two reinforcement axis positioning pieces are respectively provided at both ends of the slot.

4. The fiber reinforced thermoplastic resin composite material reinforcement splicing device according to claim 1, characterized in that: The end of the strand splitter (7) comprises a blade for cutting the composite reinforcement (1) into predetermined overlap lengths and strand numbers.

5. A method for splicing fiber-reinforced thermoplastic resin composite reinforcement bars based on the device according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: S1. The limiting cylinder (6) is embedded in the positioning hole of the lower mold (3) and welded; S2. According to the design parameters, the stock splitter (7), the overlap diameter regulator (8) and the overlap length regulator (9) are adjusted, and the pretreated composite material reinforcement (1) is placed in the adjustment groove; S3. The mold assembly is completed by the upper mold (4) limiting hole and the limiting cylinder (6); S4. The assembly is placed in the center area of ​​the panel of the flat vulcanizing press (5); S5. Preheat the flat vulcanizing press (5) to the set temperature; S6. Use a strand splitter (7) to split the reinforcement into strands in the overlapped area, cross-overlap the two strands of composite reinforcement (1), and then cover them with a thermoplastic resin sleeve (2). Wrap fiber cloth around the overlapped area according to the reinforcement requirements; S7. Place the matching overlap diameter adjuster (8) or overlap length adjuster (9) in the corresponding slot of the lower die (3) and place the pre-treated reinforcement; S8. Align the limiting hole of the upper mold (4) with the limiting cylinder (6) of the lower mold (3) and press the upper mold (4) so ​​that the limiting cylinder (6) is embedded in the limiting hole of the upper mold (4); S9. The assembled mold is placed in the middle of a flat vulcanizing press (5), the mold is closed so that the upper panel slightly contacts the surface of the upper mold (4) and continues to heat; S10. After the mold is heated to the set temperature, a predetermined pressure is applied to close the mold and press the overlap area tightly. After maintaining the temperature and pressure for a certain period of time, the temperature is lowered and the pressure is maintained until the resin solidifies. S11. After the pressure is released and the ribs are cooled to the set temperature, the mold and the ribs are removed; the upper mold (4) is lifted and the fiber-reinforced thermoplastic resin composite ribs that have been overlapped are removed.

6. The method for splicing fiber-reinforced thermoplastic resin composite reinforcement bars according to claim 5, characterized in that: The slot diameters of the lower die (3) and the upper die (4) are suitable for the maximum overlap diameter including the reinforcing material. When performing overlap without fiber reinforcement or hot pressing overlap without supplementary resin, the overlap cavity diameter is adjusted by overlap diameter adjusters (8) of different thicknesses.

7. The method for splicing fiber-reinforced thermoplastic resin composite reinforcement bars according to claim 5, characterized in that: The overlapping length of the slots provided on the lower die (3) and the upper die (4) is 200 mm. When producing overlapping test pieces with shorter overlapping lengths, overlapping length adjusters (9) with different overlapping cavity lengths and overlapping diameters are used.

8. The method for splicing fiber-reinforced thermoplastic resin composite reinforcement bars according to claim 5, characterized in that: The application of circumferentially uniform restraining force and uniform temperature field during the overlapping process is achieved through the numerical control system of the flat plate vulcanizing machine (5).

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