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

Abstract

The invention discloses a full-automatic continuous bending device and method for a fiber reinforced thermoplastic composite stirrup, and belongs to the field of material science and engineering. The device comprises a drying oven, an iron stand, a device table, a gear motor, a cam, a spline shaft, a screw rod, a stirrup winding mold and the like. The gear motor drives the spline shaft to be linked with the cam and the screw, the device table transversely moves along the linear guide rail through limiting matching of the cam and the fixing shaft, and meanwhile the screw longitudinally ascends and descends through the nut to drive the mold to finish spiral winding and bending forming of the composite material rib. The bending method comprises the following steps: preheating the composite material rib to a softening temperature, fixing the composite material rib on the die, starting the motor to enable the die to rotate and rise, limiting the transverse movement of the device table by using the cam to keep the vertical feeding of the material, and finally cooling and forming. The method can be used for preparing stirrups with different sizes, and has the advantages of efficient and continuous production, high bending strength retention rate, corrosion resistance and the like.

Description

Technical Field

[0001] The present invention belongs to the field of materials science and engineering, and in particular relates to a fully automatic continuous bending device and method for fiber-reinforced thermoplastic composite stirrups. Background Art

[0002] Fiber-reinforced resin-based composite bars (FRP bars) have become an innovative material for solving the problem of chloride ion corrosion in civil engineering infrastructure due to their light weight, high strength, corrosion resistance and fatigue resistance. They have been demonstrated in large-scale applications to replace steel bars in bridges, marine structures and other fields, increasing the service life of structures by 2-3 times and reducing the total life cycle cost by 30%. Currently, FRP bars are mainly based on thermosetting resins (epoxy / unsaturated polyester). The precise control of specific strength and modulus is achieved through the directional arrangement of fibers. As longitudinal and distribution bars in concrete structures, they can effectively control the width of cracks. However, the three-dimensional cross-linked network structure of thermosetting resins leads to insufficient fracture toughness. Microcracks initiate in the strain range of 0.5%-0.8%, and the interface debonding effect is significant in hot and humid environments, which seriously restricts their application in high-end scenarios such as nodes in super-high-rise buildings.

[0003] The molecular chains in thermoplastic resins are linear or branched, with no chemical bonds between them. The softening upon heating and the solidification upon cooling are physical changes, allowing for multiple processing and molding. Compared to thermosetting resins, they offer superior mechanical properties, impact resistance, rapid molding, toughness, recyclability, heat resistance, corrosion resistance, and convenient storage. The ability to heat and mold multiple times within a thermoplastic resin matrix makes on-site construction possible, eliminating the need for factory prefabrication and enabling rapid molding based on construction site requirements, better meeting the practical demands of civil engineering.

[0004] In the shear design of concrete structures, traditional steel stirrups, exposed to the surface of components and subjected to long-term harsh environments such as chloride corrosion and carbonization, can rust at a rate of 0.1-0.5mm / year, causing a sudden drop in the structure's bearing capacity. The use of FRP stirrups completely resolves this durability issue: leveraging their lightweight, high-strength, corrosion-resistant, fatigue-resistant, and non-magnetic properties, these properties reduce the lifecycle cost of structures in corrosive environments such as offshore platforms. They also eliminate maintenance measures such as cathodic protection, significantly extending their service life and generating significant economic benefits.

[0005] Currently, existing bending devices suffer from low efficiency, uneven heating, and inability to meet practical needs. Therefore, it is necessary to develop a fully automatic device for the production of fiber-reinforced thermoplastic resin composite stirrups that can efficiently produce fiber-reinforced thermoplastic resin composite stirrups with a high flexural 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 prepare fiber-reinforced thermoplastic resin composite stirrups and has a high bending strength retention rate.

[0007] In order to achieve the above-mentioned purpose, 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, an apparatus table, a fixed shaft, a reduction motor, a cam, a spline 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 apparatus table, the spline shaft is inserted into the reduction motor, the cam, the fixed shaft and the screw are sequentially installed on the spline shaft, the nut is fixed on the apparatus table and connected to the screw; the stirrup winding mold is fixed on the screw, the apparatus table is fixed on the linear guide rail of the iron frame table through the support frame, and the fixed shaft is in contact with the cam; the oven is placed on the iron frame table and is equipped with a removable oven cover.

[0008] Furthermore, the positioning groove under the device table is used to fix the reduction motor, the support frame can slide on the linear guide rail, and the fixed shaft is fixed to the iron frame table through the connecting bracket. When the reduction motor is started, the fixed shaft limits the rotation of the cam, so that the cam drives the device table to move left and right.

[0009] Furthermore, the spline shaft can realize clockwise rotation, counterclockwise rotation, rising and falling functions through the control of the reduction motor, and the cam, fixed shaft and screw can move on the spline shaft.

[0010] Furthermore, the nut shaft is hollow and is used to insert and fix the screw rod, and control the screw rod to move up and down during the preparation process.

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

[0012] Furthermore, the oven can be adjusted to control temperature, with a maximum temperature of 400° C. When the oven cover is closed, it can ensure that the temperature inside the oven rises quickly and is kept warm.

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

[0014] S1: heating the oven to the softening temperature of the fiber-reinforced thermoplastic resin composite material bar; placing the fiber-reinforced thermoplastic resin composite material bar in the oven and heating it until softened, placing it into the stirrup winding mold to fit tightly, and fixing it with a fixing handle;

[0015] S2: Start the reduction 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, causing the stirrup winding mold to rotate and rise, driving the composite material reinforcement to form continuous stirrups;

[0016] S3: During the bending process, the fixed shaft limits the rotation of the cam, so that the composite reinforcement remains in the same vertical plane and is fed into the stirrup winding die;

[0017] S4: Turn off the reduction motor, remove the fixed handle, and remove the fiber reinforced thermoplastic resin composite continuous stirrups 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 materials of different sizes, and can efficiently prepare fiber-reinforced thermoplastic resin composite stirrups with a high bending strength retention rate, with the advantages of convenience, speed and cost saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It 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 It 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 It is a three-dimensional schematic diagram of the iron frame provided by the present invention;

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

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

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

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

[0028] Explanation of the accompanying reference numerals: 1-oven; 2-iron frame; 3-device table; 4-fixed shaft; 5-reduction motor; 6-cam; 7-spline shaft; 8-screw; 9-stirrup winding mold; 10-fiber reinforced thermoplastic resin composite material rib; 11-nut; 12-support frame; 13-linear guide; 14-fixed handle; 15-oven cover. DETAILED DESCRIPTION

[0029] This invention utilizes the characteristics of fiber-reinforced thermoplastic resin composite reinforcement bars: they soften upon heating, are easily shaped, and harden upon cooling. It proposes a fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups. This device can efficiently produce fiber-reinforced thermoplastic resin composite stirrups with a high degree of bending strength retention. To better illustrate the objectives, technical solutions, and advantages of the present invention, the invention will be further described below with reference to the accompanying drawings and specific examples.

[0030] Example 1

[0031] A fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups comprises an oven 1, an iron frame 2, an installation platform 3, a fixed shaft 4, a reduction motor 5, a cam 6, a spline shaft 7, a screw 8, a stirrup winding die 9, a nut 11, a support frame 12, a linear guide 13, and an oven cover 15. The reduction motor 5 is inserted into a positioning slot of the installation platform 3, the spline shaft 7 is inserted into the reduction motor 5, the cam 6, fixed shaft 4, and screw 8 are sequentially mounted on the spline shaft 7, the nut 11 is fixed to the installation platform 3 and connected to the screw 8, the stirrup winding die 9 is fixed to the screw 8, the installation platform 3 is fixed to the linear guide 13 of the iron frame 2 via the support frame 12, and the fixed shaft 4 is in contact with 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 can be adjusted and controlled to a maximum temperature of 400°C. When the oven cover 15 is closed, it ensures that the temperature inside the oven 1 rises rapidly and remains warm. The positioning groove under the device platform 3 is used to fix the reduction motor 5. The support frame 12 can slide on the linear guide rail 13. The fixed shaft 4 is fixed on the iron frame platform 2 through the connecting bracket 12. When the reduction motor 5 is started, the fixed shaft 4 limits the rotation of the cam 6, so that the cam 6 drives the device platform 3 to move left and right. The spline shaft 7 is controlled by the reduction motor 5 to realize 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 axis and is used to insert and fix the screw 8, and control the up and down movement of the screw 8 during the preparation process. A groove is provided on the stirrup winding mold 9 for inserting the fixed 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, first embed the reduction motor into the positioning groove of the device table, insert the spline shaft, install the cam and screw on the spline shaft in sequence, fix the nut on the device table, and connect the screw to the nut; then select a stirrup winding mold with a length and width of 150mm and a bending radius of 30mm and fix it on the screw, fix the device table to the two linear guide rails on the iron frame table through the support frame, adjust the position of the fixed shaft so that it contacts the cam; connect the oven to the power supply and place it on the iron frame table, and cover the oven lid; finally, check the working conditions of the oven and the device to complete the assembly of the fully automatic continuous stirrup bending device.

[0034] The production process of continuous stirrups of fiber-reinforced thermoplastic resin composite materials is as follows: first, the oven is heated to 300°C to reach the softening temperature of the fiber-reinforced thermoplastic resin composite materials; a fiber-reinforced thermoplastic resin composite material reinforcement with a length of 2m and a diameter of 12mm is placed in the oven and heated for 10 minutes. After it is softened, the composite material reinforcement is sent into the stirrup winding mold to fit tightly and fixed by a fixed handle; the reduction motor is started to drive the spline shaft to rotate, thereby driving the stirrup winding mold to rotate; at the same time, the screw rises, causing the stirrup winding mold to rotate and rise, driving the composite material reinforcement to form continuous stirrups; during the bending process, the fixed shaft limits the rotation of the cam, so that the composite material reinforcement remains in the same vertical plane and is sent into the stirrup winding mold; finally, the reduction motor is turned off, the fixed handle is removed, and the continuous stirrups of fiber-reinforced thermoplastic resin composite materials are removed from the stirrup winding mold.

[0035] Example 3

[0036] During the assembly stage of the bending device, first embed the reduction motor into the positioning groove of the device table, insert the spline shaft, install the cam and screw on the spline shaft in sequence, fix the nut on the device table, and connect the screw to the nut; then select a stirrup winding mold with a length and width of 200mm and a bending radius of 60mm and fix it on the screw, fix the device table to the two linear guide rails on the iron frame through the support frame, adjust the position of the fixed shaft so that it contacts the cam; connect the oven to the power supply and place it on the iron frame, and cover the oven lid; finally, check the working conditions of the oven and the device to complete the assembly of the fully automatic continuous stirrup bending device.

[0037] The production process of continuous stirrups of fiber-reinforced thermoplastic resin composite materials is as follows: first, the oven is heated to 300°C to reach the softening temperature of the fiber-reinforced thermoplastic resin composite materials; a fiber-reinforced thermoplastic resin composite material reinforcement with a length of 3m and a diameter of 10mm is placed in the oven and heated for 10 minutes. After it is softened, the composite material reinforcement is sent into the stirrup winding mold to fit tightly and fixed by a fixed handle; the reduction motor is started to drive the spline shaft to rotate, thereby driving the stirrup winding mold to rotate; at the same time, the screw rises, causing the stirrup winding mold to rotate and rise, driving the composite material reinforcement to form continuous stirrups; during the bending process, the fixed shaft limits the rotation of the cam, so that the composite material reinforcement remains in the same vertical plane and is sent into the stirrup winding mold; finally, the reduction motor is turned off, the fixed handle is removed, and the continuous stirrups of fiber-reinforced thermoplastic resin composite materials are removed from the stirrup winding mold.

[0038] Within the technical scope of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple variations and combinations should also be considered as disclosed in the present invention and fall within the scope of protection of the claims of the present invention.

Claims

1. A fully automatic continuous bending device for fiber-reinforced thermoplastic composite stirrups, comprising an oven, an iron frame, a device table, a fixed shaft, a reduction motor, a cam, a spline shaft, a screw, a stirrup winding die, a nut, a support frame, a linear guide rail, and an oven cover; characterized in that: The reduction motor is embedded in the positioning groove of the device table, the spline shaft is inserted into the reduction motor, the cam, fixed shaft and screw are installed on the spline shaft in sequence, the nut is fixed on the device table and connected to the screw; the stirrup winding mold is fixed on the screw, the device table is fixed on the linear guide rail of the iron frame table through the support frame, and the fixed shaft is in contact with the cam; the oven is placed on the iron frame table and is equipped with a removable oven cover.

2. The fully automatic continuous stirrup bending device according to claim 1, characterized in that: The positioning groove under the device table is used to fix the reduction motor, the support frame can slide on the linear guide rail, and the fixed shaft is fixed to the iron frame table through the connecting bracket. When the reduction motor is started, the fixed shaft limits the rotation of the cam, so that the cam drives the device table to move left and right.

3. The fully automatic continuous stirrup bending device according to claim 1, characterized in that: The spline shaft can realize clockwise rotation, counterclockwise rotation, rising and falling functions through the control of a reduction motor, and the cam, fixed shaft and screw can move on the spline shaft.

4. The fully automatic continuous stirrup bending device according to claim 1, characterized in that: The nut shaft is hollow and is used to insert and fix the screw rod, and control the screw rod to move up and down during the preparation process.

5. The fully automatic continuous stirrup bending device according to claim 1, characterized in that: A groove is provided on the stirrup winding mold for inserting a fixed handle, and the stirrup winding mold can be replaced with molds of different sizes.

6. The fully automatic continuous stirrup bending device according to claim 1, characterized in that: The oven can be adjusted to control temperature, with a maximum temperature of 400° C. When the oven cover is closed, the temperature inside the oven can be quickly raised and kept warm.

7. A method for bending fiber-reinforced thermoplastic resin composite material bars based on the bending device according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: heating the oven to the softening temperature of the fiber reinforced thermoplastic resin composite material; The fiber-reinforced thermoplastic resin composite reinforcement is placed in an oven and heated until softened, then placed into a stirrup winding mold to fit tightly together and fixed with a fixed handle; S2: Start the reduction 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, causing the stirrup winding mold to rotate and rise, driving the composite material reinforcement to form continuous stirrups; S3: During the bending process, the fixed shaft limits the rotation of the cam, so that the composite reinforcement remains in the same vertical plane and is fed into the stirrup winding die; S4: Turn off the reduction motor, remove the fixed handle, and remove the fiber reinforced thermoplastic resin composite continuous stirrups from the stirrup winding mold.

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