Full-automatic continuous bending device and method for fiber-reinforced thermoplastic composite stirrup

Abstract

The application discloses a kind of full-automatic continuous bending device and method of fiber reinforced thermoplastic composite stirrup, belong to material science and engineering field.Device includes oven, iron stand, device table, reduction motor, cam, spline shaft, screw rod and stirrup winding mould and other components.Reduction motor drives spline shaft linkage cam and screw rod, through the limiting cooperation of cam and fixed shaft, make device table move laterally along linear guide rail, while screw rod realizes longitudinal lifting by screw nut, drive mould to complete the spiral winding and bending forming of composite material bar.Bending method includes: composite material bar is preheated to softening temperature, it is fixed in mould, start motor to make mould rotate and ascend, limit device table lateral movement using cam to keep material vertical feeding, finally cooling forming.The application can prepare different size stirrup, with the advantages of efficient continuous production, bending strength retention rate is high, corrosion resistant and the like.

Description

Technical Field

[0001] This invention belongs to the field of materials science and engineering, and specifically relates to a fully automatic continuous bending device and method for fiber-reinforced thermoplastic composite stirrups. Background Technology

[0002] Fiber-reinforced resin matrix composite (FRP) bars, with their lightweight, high strength, corrosion resistance, and fatigue resistance, have become a revolutionary material for solving chloride ion corrosion problems in civil engineering infrastructure. They have achieved large-scale demonstration applications in bridges, marine structures, and other fields, replacing steel bars and extending structural service life by 2-3 times while reducing total life-cycle costs by 30%. Currently, FRP bars mainly use thermosetting resins (epoxy / unsaturated polyester) as the matrix, achieving precise control of specific strength and modulus through fiber orientation. As longitudinal and distribution reinforcement in concrete structures, they can effectively control crack width. However, the three-dimensional cross-linked network structure of thermosetting resins leads to insufficient fracture toughness, with microcracks initiating in the 0.5%-0.8% strain range. Furthermore, significant interfacial debonding effects occur under humid and hot environments, severely limiting their application in high-end scenarios such as high-rise building joints.

[0003] Thermoplastic resins have linear or branched molecular chains with no chemical bonds between them. Their softening upon heating and curing upon cooling are physical changes, allowing for multiple molding processes. Compared to thermosetting resins, they offer superior mechanical properties, impact resistance, faster molding speeds, better toughness, recyclability, temperature resistance, corrosion resistance, and easier storage. The ability of thermoplastic resin matrices to be repeatedly heated and molded makes on-site construction possible, moving beyond factory prefabrication and allowing for rapid molding to meet the specific needs of the construction site, thus better satisfying the practical requirements of civil engineering.

[0004] In the shear design of concrete structures, traditional steel stirrups, exposed on the surface of the member, are subjected to harsh environments such as chloride corrosion and carbonization for extended periods, resulting in a corrosion rate of 0.1-0.5 mm / year and a sharp drop in structural load-bearing capacity. Using FRP stirrups can completely solve this durability problem: leveraging their advantages of being lightweight, high-strength, corrosion-resistant, fatigue-resistant, and non-magnetic, these characteristics reduce the life-cycle cost of structures in corrosive environments such as offshore platforms, while eliminating the need for cathodic protection and other maintenance measures, significantly extending service life and resulting in substantial economic benefits.

[0005] Currently, existing bending devices suffer from problems such as low efficiency, uneven heating, and inability to meet practical needs. Therefore, there is a need to develop a fully automated device for producing fiber-reinforced thermoplastic resin composite stirrups, which can efficiently produce fiber-reinforced thermoplastic resin composite stirrups and has a high bending strength retention rate. Summary of the Invention

[0006] In view of the above shortcomings, the present invention provides a fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups, which can efficiently produce fiber-reinforced thermoplastic resin composite stirrups and has a high bending strength retention rate.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups, comprising an oven, an iron frame, a device platform, a fixed shaft, a reduction motor, a cam, a splined shaft, a screw, a stirrup winding mold, a nut, a support frame, a linear guide rail, and an oven cover; the reduction motor is embedded in the positioning groove of the device platform, the splined shaft is inserted into the reduction motor, the cam, the fixed shaft, and the screw are sequentially mounted on the splined shaft, the nut is fixed on the device platform and connected to the screw; the stirrup winding mold is fixed on the screw, the device platform is fixed on the linear guide rail of the iron frame through the support frame, and the fixed shaft is in contact with the cam; the oven is placed on the iron frame and is equipped with a removable oven cover.

[0008] Furthermore, the device has a positioning slot under the platform for fixing the geared motor, the support frame can slide on the linear guide rail, and the fixed shaft is fixed to the iron frame platform through the connecting bracket. When the geared motor starts, the fixed shaft restricts the rotation of the cam, so that the cam drives the device platform to move left and right.

[0009] Furthermore, the spline shaft is controlled by a geared motor to achieve clockwise rotation, counterclockwise rotation, rising, and falling functions, and the cam, fixed shaft, and screw can move on the spline shaft.

[0010] Furthermore, the nut shaft is hollow, used to insert and fix the screw, and to control the up and down movement of the screw during the manufacturing process.

[0011] Furthermore, the stirrup winding mold is provided with a groove for inserting a fixing handle, and the stirrup winding mold can be replaced with molds of different sizes.

[0012] Furthermore, the oven has adjustable temperature control, with a maximum temperature of 400℃, and the oven lid ensures rapid heating and heat preservation inside the oven.

[0013] Another object of the present invention is to provide a bending method for fiber-reinforced thermoplastic resin composite ribs based on the bending device described above, comprising the following steps:

[0014] S1: Heat the oven to the softening temperature of the fiber-reinforced thermoplastic resin composite bar; place the fiber-reinforced thermoplastic resin composite bar in the oven and heat until softened, then send it into the stirrup winding mold for tight bonding and fix it with the fixing handle;

[0015] S2: Start the geared motor to drive the spline shaft to rotate, which in turn drives the stirrup winding mold to rotate. At the same time, the screw rises, so that the stirrup winding mold rotates and rises at the same time, driving the composite material reinforcement to form a continuous stirrup.

[0016] S3: During the bending process, the fixed shaft restricts the rotation of the cam, keeping the composite material reinforcement in the same vertical plane as it is fed into the stirrup winding mold;

[0017] S4: Turn off the geared motor, remove the fixing handle, and remove the fiber-reinforced thermoplastic resin composite continuous stirrup from the stirrup winding mold.

[0018] The present invention has the following advantages and beneficial effects: The present invention can realize the preparation of continuous stirrups of fiber-reinforced thermoplastic resin composite material of different sizes, and can also prepare fiber-reinforced thermoplastic resin composite material stirrups with high efficiency and high bending strength retention rate, which has the advantages of convenience, speed and cost saving. Attached Figure Description

[0019] Figure 1 This is a three-dimensional schematic diagram of a fully automatic continuous stirrup bending device provided by the present invention;

[0020] Figure 2 This is a front view of a fully automatic continuous stirrup bending device provided by the present invention;

[0021] Figure 3 This is a side view of a fully automatic continuous stirrup bending device provided by the present invention;

[0022] Figure 4 This is a top view of a fully automatic continuous stirrup bending device provided by the present invention;

[0023] Figure 5 This is a three-dimensional schematic diagram of the iron frame provided by the present invention;

[0024] Figure 6 This is a three-dimensional schematic diagram of the drying oven provided by the present invention;

[0025] Figure 7 This is a three-dimensional schematic diagram of the device platform provided by the present invention;

[0026] Figure 8 This is a three-dimensional schematic diagram of the spline shaft provided by the present invention;

[0027] Figure 9 This is a three-dimensional schematic diagram of the bending device platform provided by the present invention;

[0028] Explanation of reference numerals in the attached drawings: 1-Oven; 2-Iron frame; 3-Device platform; 4-Fixed shaft; 5-Gear motor; 6-Cam; 7-Splined shaft; 8-Screw; 9-Stirrup winding mold; 10-Fiber reinforced thermoplastic resin composite material rib; 11-Thread nut; 12-Support frame; 13-Linear guide rail; 14-Fixed handle; 15-Oven cover. Detailed Implementation

[0029] This invention utilizes the characteristics of fiber-reinforced thermoplastic resin composite stirrups—softening upon heating, easy shaping, and hardening upon cooling—to propose a fully automated continuous bending device for fiber-reinforced thermoplastic resin composite stirrups. This device can efficiently produce fiber-reinforced thermoplastic resin composite stirrups and maintain a high bending strength retention rate. To better illustrate the purpose, technical solution, and advantages of this invention, the following will further describe the invention in conjunction with the accompanying drawings and specific embodiments.

[0030] Example 1

[0031] An automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups includes an oven 1, an iron frame 2, a device platform 3, a fixed shaft 4, a reduction motor 5, a cam 6, a splined shaft 7, a screw 8, a stirrup winding mold 9, a nut 11, a support frame 12, a linear guide rail 13, and an oven cover 15. The reduction motor 5 is embedded in the positioning groove of the device platform 3, and the splined shaft 7 is inserted into the reduction motor 5. The cam 6, fixed shaft 4, and screw 8 are sequentially mounted on the splined shaft 7. The nut 11 is fixed to the device platform 3 and connected to the screw 8. The stirrup winding mold 9 is fixed to the screw 8. The device platform 3 is fixed to the linear guide rail 13 of the iron frame 2 via the support frame 12. The fixed shaft 4 contacts the cam 6. The oven 1 is placed on the iron frame 3 and is equipped with a removable oven cover 15. The oven 1 has adjustable temperature control, with a maximum temperature of 400℃. The oven cover 15 ensures rapid heating and heat preservation inside the oven 1. The device platform 3 has a positioning groove for fixing the geared motor 5. The support frame 12 can slide on the linear guide rail 13. The fixed shaft 4 is fixed to the iron frame platform 2 through the connecting bracket 12. When the geared motor 5 starts, the fixed shaft 4 restricts the rotation of the cam 6, causing the cam 6 to drive the device platform 3 to move left and right. The spline shaft 7 is controlled by the geared motor 5 to achieve clockwise rotation, counterclockwise rotation, rising, and falling functions. The cam 6, fixed shaft 4, and screw 8 can move on the spline shaft 7. The nut 11 has a hollow shaft for inserting and fixing the screw 8, and controls the up and down movement of the screw 8 during the preparation process. The stirrup winding mold 9 has a groove for inserting and fixing the handle 14. The stirrup winding mold 9 can be replaced with molds of different sizes.

[0032] Example 2

[0033] During the assembly stage of the bending device, firstly, the geared motor is embedded into the positioning slot of the device table, the spline shaft is inserted, and the cam and screw are installed onto the spline shaft in sequence. The nut is fixed on the device table, and the screw is connected to the nut. Then, a stirrup winding mold with a length and width of 150mm and a bending radius of 30mm is selected and fixed on the screw. The device table is fixed on the two linear guide rails on the iron frame through the support frame, and the position of the fixed shaft is adjusted so that it contacts the cam. After connecting the power supply to the oven, it is placed on the iron frame and the oven cover is closed. Finally, the working condition of the oven and the device is checked, and the assembly of the fully automatic continuous stirrup bending device is completed.

[0034] The production process of continuous stirrups made of fiber-reinforced thermoplastic resin composite material is as follows: First, the oven is heated to 300℃ to reach the softening temperature of the fiber-reinforced thermoplastic resin composite material. A 2m long and 12mm diameter fiber-reinforced thermoplastic resin composite material is placed in the oven and heated for 10 minutes until softened. Then, the composite material is fed into the stirrup winding mold, where it is tightly fitted and secured by a fixed handle. The geared motor is started, causing the spline shaft to rotate, which in turn rotates the stirrup winding mold. Simultaneously, the screw rises, causing the stirrup winding mold to rotate and rise, forming a continuous stirrup. During bending, the fixed shaft restricts the rotation of the cam, keeping the composite material in the same vertical plane as it enters the stirrup winding mold. Finally, the geared motor is turned off, the fixed handle is removed, and the continuous stirrup made of fiber-reinforced thermoplastic resin composite material is removed from the stirrup winding mold.

[0035] Example 3

[0036] During the assembly stage of the bending device, firstly, the geared motor is embedded into the positioning slot of the device table, the spline shaft is inserted, and the cam and screw are installed onto the spline shaft in sequence. The nut is fixed on the device table, and the screw is connected to the nut. Then, a stirrup winding mold with a length and width of 200mm and a bending radius of 60mm is selected and fixed on the screw. The device table is fixed on the two linear guide rails on the iron frame through the support frame, and the position of the fixed shaft is adjusted so that it contacts the cam. After connecting the power supply to the oven, it is placed on the iron frame and the oven cover is closed. Finally, the working condition of the oven and the device is checked, and the assembly of the fully automatic continuous stirrup bending device is completed.

[0037] The production process of continuous stirrups made of fiber-reinforced thermoplastic resin composite material is as follows: First, the oven is heated to 300℃ to reach the softening temperature of the fiber-reinforced thermoplastic resin composite material. A 3m long and 10mm diameter fiber-reinforced thermoplastic resin composite material is placed in the oven and heated for 10 minutes until softened. Then, the composite material is fed into the stirrup winding mold, where it is tightly fitted and secured by a fixed handle. The geared motor is started, causing the spline shaft to rotate, which in turn rotates the stirrup winding mold. Simultaneously, the screw rises, causing the stirrup winding mold to rotate and rise, forming a continuous stirrup. During bending, the fixed shaft restricts the rotation of the cam, keeping the composite material in the same vertical plane as it enters the stirrup winding mold. Finally, the geared motor is turned off, the fixed handle is removed, and the continuous stirrup made of fiber-reinforced thermoplastic resin composite material is removed from the stirrup winding mold.

[0038] Within the scope of the inventive concept, various simple modifications can be made to the technical solution of the present invention, including combinations of specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not further describe the various possible combinations. However, these simple modifications and combinations should also be considered as part of the content disclosed in this invention and are all within the protection scope of the claims of this invention.

Claims

1. A fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups, comprising an oven, an iron frame, a device platform, a fixed shaft, a geared motor, a cam, a splined shaft, a screw, a stirrup winding mold, a nut, a support frame, a linear guide rail, and an oven cover; characterized in that, The geared motor is embedded in the positioning slot of the device platform, the splined shaft is inserted into the geared motor, the cam and screw are sequentially mounted on the splined shaft, the nut is fixed on the device platform and connected to the screw; the hoop winding mold is fixed on the screw, the device platform is fixed on the linear guide rail of the iron frame platform by the support frame, and the fixed shaft is in contact with the cam; the oven is placed on the iron frame platform and is equipped with a removable oven cover; the device platform has a positioning slot for fixing the geared motor, the support frame slides on the linear guide rail, and the fixed shaft is fixed on the iron frame platform by the connecting bracket. When the geared motor starts, the fixed shaft restricts the rotation of the cam, causing the cam to drive the device platform to move left and right.

2. The fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups according to claim 1, characterized in that, The splined shaft is controlled by a geared motor to achieve clockwise rotation, counterclockwise rotation, rising, and falling functions, and the screw moves on the splined shaft.

3. The fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups according to claim 1, characterized in that, The nut shaft is hollow and is used to insert and fix the screw, and to control the up and down movement of the screw during the manufacturing process.

4. The fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups according to claim 1, characterized in that, The stirrup winding mold is provided with a groove for inserting a fixing handle, and the stirrup winding mold can be replaced with molds of different sizes.

5. The fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups according to claim 1, characterized in that, The oven has adjustable temperature control, with a maximum temperature of 400℃. When the oven lid is closed, it can ensure rapid heating and heat preservation inside the oven.

6. A bending method for fiber-reinforced thermoplastic composite rebar based on the fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups according to any one of claims 1-5, characterized in that, Includes the following steps: S1: Heat the oven to the softening temperature of the fiber-reinforced thermoplastic composite rib; The fiber-reinforced thermoplastic resin composite bar is placed in an oven and heated until softened, then fed into a stirrup winding mold for tight bonding and fixed with a fixing handle; S2: Start the geared motor to drive the spline shaft to rotate, which in turn drives the stirrup winding mold to rotate. At the same time, the screw rises, so that the stirrup winding mold rotates and rises at the same time, driving the composite material reinforcement to form a continuous stirrup. S3: During the bending process, the fixed shaft restricts the rotation of the cam, keeping the composite material reinforcement in the same vertical plane as it is fed into the stirrup winding mold; S4: Turn off the geared motor, remove the fixing handle, and remove the fiber-reinforced thermoplastic resin composite continuous stirrup from the stirrup winding mold.

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