Glass fiber reinforced plastic correction device and method

Abstract

The glass fiber reinforced plastic correction device is characterized in that the glass fiber reinforced plastic correction device comprises a top plate (1), a pressing block (3), a positioning plate (4) and a heating plate (5), the four ends of the bottom of the top plate (1) are welded to the tops of four supporting rods (6), and the bottoms of the four supporting rods (6) are welded to a bottom plate (7); the four ends of the positioning plate (4) are arranged outside the supporting rods (6) in a sleeving mode, the supporting rods (6) are welded to the positioning plate (4), the heating plate (5) is arranged below the positioning plate (4), the top of the heating plate (5) is tightly attached to the positioning plate (4), and a heating coil is arranged in the heating plate (5). Four hydraulic rods (2) are installed at the bottom of the top plate (1), two pressing blocks (3) are arranged below the four hydraulic rods (2), and the telescopic ends of the bottoms of every two hydraulic rods (2) are welded to the top of one pressing block (3). According to the invention, the problems that the thickness of the product is inconsistent, the shrinkage stress of each area is different, and the shape and size of the product are changed due to the release of residual stress are solved.

Description

Technical Field

[0001] The invention relates to the technical field of glass fiber reinforced plastic processing, and in particular to a glass fiber reinforced plastic correction device and method. Background Art

[0002] The non-uniformity of the linear expansion coefficient of FRP is the fundamental reason for the deformation of FRP plates. This is a common problem of this type of material and is inevitable in FRP products. What needs to be done is to reduce the deformation variable to a minimum. The resin in this type of material condenses under high temperature and high pressure to release heat energy. After the hot pressing is completed, the high temperature is reduced to room temperature, which causes the product to change in shape. It is speculated that if the FRP is demolded at high temperature, it will lose its restraint (the mold is a rigid body in this assumption), causing the internal resin to expand and not condense, resulting in a large volume. The residual stress deforms toward the unrestrained point, thereby causing the FRP structural member to warp or twist. For this reason, the present invention proposes a FRP correction device and method to solve the problems of inconsistent product thickness, differences in shrinkage stress in various regions, and changes in the shape and size of the product caused by the release of residual stress. Summary of the invention

[0003] In view of the deficiencies of the prior art, the present invention provides a FRP correction device and method, which solves the problems in the prior art of inconsistent product thickness, differences in shrinkage stress in various regions, and changes in shape and size of the product caused by the release of residual stress.

[0004] A glass fiber reinforced plastic correction device, characterized in that it includes a top plate 1, a pressure block 3, a positioning plate 4 and a heating plate 5, the four ends of the bottom of the top plate 1 are welded to the tops of four support rods 6, and the bottoms of the four support rods 6 are welded to the bottom plate 7; the four ends of the positioning plate 4 are sleeved on the outside of the support rods 6, and the support rods 6 are welded to the positioning plate 4, a heating plate 5 is provided below the positioning plate 4, the top of the heating plate 5 is tightly fitted with the positioning plate 4, and a heating coil is provided inside the heating plate 5; four hydraulic rods 2 are installed at the bottom of the top plate 1, and there are two pressure blocks 3 under the four hydraulic rods 2, and the telescopic ends of the bottoms of every two hydraulic rods 2 are welded to the top of a pressure block 3; the two lower end surfaces of the two pressure blocks 3 are fixedly connected to the upper surface of the positioning plate 4; the pressure block 3 is in an inverted U shape; two positioning grooves 8 are also provided on the upper surface of the positioning plate 4, and the two positioning grooves 8 are arranged in parallel; the middle part of the pressure block 3 is arranged above the positioning groove 8.

[0005] The heating coils inside the heating plate 5 are distributed in a multi-bend shape, and the contact surface between the heating plate 5 and the positioning plate 4 is a copper plate.

[0006] The shape of the positioning groove 8 on the surface of the positioning plate 4 matches the shape of the FRP product. The depth of the positioning groove 8 is less than the thickness of the FRP product. The top of the FRP product protrudes from the upper surface of the positioning plate 4 .

[0007] A method for correcting glass fiber reinforced plastics, using the glass fiber reinforced plastics correcting device described above, is characterized in that the steps are as follows:

[0008] Step 1: After the product is solidified to a certain strength, it is demoulded. The mold consists of three parts: upper, middle and lower. The demoulding method is to open the upper mold first, and then disassemble the middle mold and the lower mold. At this time, the product is fixed on the middle mold. The mold is knocked by a rubber hammer through the manual demoulding method. Due to the vibration, the fiberglass product is separated from the mold;

[0009] Step 2: After demoulding, the product needs to be processed in time to remove burrs and burrs, repair surface and internal defects, and the mold shrinkage rate, sealing, demoulding angle, surface finish, mold strength, rigidity, and wear resistance must meet the design requirements;

[0010] Step 3: After molding and demoulding, the product should be placed for 24 hours before heating and curing. The product is placed in the positioning groove 8 so that the product can be embedded in the positioning groove 8 for fixation. The heating plate 5 is connected to the external heating power supply. The positioning plate 4 is slowly heated by the heating of the heating plate 5. The positioning plate 4 is heated while the product is heated.

[0011] Step 4: Synchronously extend and retract the telescopic end of the hydraulic rod 2 so that the hydraulic rod 2 can drive the pressing block 3 to move up and down. By moving the pressing block 3 downward, the two ends of the pressing block 3 can press down the warped parts of the glass fiber reinforced plastic product at both ends, thereby performing a curing process.

[0012] In the step 3, the temperature at which the heating plate 5 heats and cures the positioning plate 4 is slightly lower than the resin thermal deformation temperature of 80°C-100°C, and then the curing treatment is carried out at this temperature for 4-8 hours, with a heating rate of 10°C / h.

[0013] In the step 3, the FRP product should be heated evenly to avoid local overheating, and during the heating process, a hot air blower is used to blow hot air to the surface of the product to heat it, thereby reducing the temperature difference between the inside and outside of the FRP product.

[0014] The bottom pressure surface of the pressing block 3 should be kept flat, and the bottom pressure surface of the pressing block 3 should be kept parallel to the horizontal plane when pressing downward to avoid uneven force on both ends of the glass fiber reinforced plastic product during the pressing process.

[0015] When the FRP product is bent upward, the upper surface temperature needs to be appropriately lowered, and no auxiliary heating is required through a blast device during the heating process. When it is bent downward, the lower surface temperature needs to be appropriately lowered and the upper surface temperature needs to be increased, and a blast device is used to perform auxiliary heating through hot air flow.

[0016] Beneficial effects of the present invention:

[0017] The present invention is a glass fiber reinforced plastic product that is cold-cured at room temperature. After being formed and demolded, it is placed for 24 hours and then heated and cured, which is beneficial to avoid overheating deformation of the product. The heating and curing temperature is lower than the thermal deformation temperature of the resin, and then the curing treatment is carried out at this temperature. The product is heated evenly. After such treatment, the curing can be almost complete and the product can maintain the stability of size and structure, thereby solving the problems of inconsistent product thickness, different shrinkage stresses in various regions, and changes in shape and size of the product caused by the release of residual stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 , is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 , is a schematic diagram of the side structure of the present invention;

[0020] Figure 3 , is a front view structural diagram of the present invention;

[0021] Figure 4 , is a schematic diagram of the positioning groove structure of the present invention;

[0022] Figure 5 , is a flow chart of the method of the present invention;

[0023] Figure 6 , Schematic diagram of FRP before correction

[0024] Figure 7 , is a schematic diagram of the fiberglass after correction.

[0025] In the figure, 1, top plate; 2, hydraulic rod; 3, pressure block; 4, positioning plate; 5, heating plate; 6, support rod; 7, bottom plate; 8, positioning groove. DETAILED DESCRIPTION

[0026] To achieve the above objectives, the present invention is implemented through the following technical solutions: a fiberglass straightening device and method, comprising a top plate, a pressure block, a positioning plate and a heating plate, the four ends of the bottom of the top plate are welded to the top of the support rod, there are four support rods, the bottoms of the four support rods are welded to the bottom plate, a hydraulic rod is installed at the bottom of the top plate, the telescopic end of the bottom of the hydraulic rod is welded to the top of the pressure block, there are two pressure blocks, the two pressure blocks are arranged above the positioning plate, the four ends of the positioning plate are mounted on the outside of the support rod, and the support rod is welded to the positioning plate, a heating plate is provided under the positioning plate, the top of the heating plate is tightly fitted with the positioning plate, and a heating coil is provided inside the heating plate.

[0027] Preferably, the pressing block is arranged in a U shape, the pressing block is arranged above the positioning groove, the positioning groove is opened on the top surface of the positioning plate, two positioning grooves are provided, and the two positioning grooves are arranged in parallel.

[0028] Preferably, the heating coils inside the heating plate are distributed in a multi-curved shape, and the contact surface between the heating plate and the positioning plate is a copper plate.

[0029] Preferably, the shape of the positioning groove on the surface of the positioning plate matches the shape of the FRP product, the depth of the positioning groove is less than the thickness of the FRP product, and the top of the FRP product protrudes from the upper surface of the positioning plate.

[0030] Preferably, the steps are as follows:

[0031] S1: After the product is solidified to a certain strength, it is demoulded. The mold consists of three parts: upper, middle and lower. The demoulding method is to open the upper mold first, and then disassemble the middle mold and the lower mold. At this time, the product is fixed on the middle mold. The mold is knocked by a rubber hammer through the manual demoulding method. Due to the vibration, the FRP product is separated from the mold;

[0032] S2: After demoulding, the product needs to be processed in time to remove burrs and burrs, repair surface and internal defects, and the mold shrinkage rate, sealing, demoulding angle, surface finish, mold strength, rigidity, and wear resistance must meet the design requirements;

[0033] S3: After molding and demoulding, it should be placed for 24 hours before heating and curing. The product is placed in the positioning groove so that the product can be embedded in the positioning groove for fixation. The heating plate is connected to the external heating power supply. The positioning plate is slowly heated by the heating plate. The positioning plate is heated and the product is heated at the same time.

[0034] S4: The hydraulic rod telescopic end is synchronously extended and retracted, so that the hydraulic rod can drive the pressing block to move up and down. The pressing block moves downward, so that the people at both ends of the pressing block can press down the warped parts of the FRP product at both ends, thereby performing the curing process.

[0035] Preferably, the temperature at which the heating plate heats and cures the positioning plate in S3 is slightly lower than the thermal deformation temperature of the resin, 80°C-100°C, and then the curing treatment is carried out at this temperature for 4-8 hours, with a heating rate of 10°C / h.

[0036] Preferably, the FRP product in S3 is heated evenly to avoid local overheating, and during the heating process, a hot air blower is used to blow hot air to the surface of the product to heat it, thereby reducing the temperature difference between the inside and outside of the FRP product.

[0037] Preferably, the bottom pressure surface of the pressing block should be kept flat, and the bottom pressure surface of the pressing block should be kept parallel to the horizontal plane when pressing downward to avoid uneven force on both ends of the FRP product during the pressing process.

[0038] Preferably, when the FRP product is bent upward, the upper surface temperature needs to be appropriately lowered, and no auxiliary heating is required through a blast device during the heating process. When it is bent downward, the lower surface temperature needs to be appropriately lowered and the upper surface temperature needs to be increased, and a blast device is used to perform auxiliary heating through hot air flow.

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Embodiment 1:

[0041] A glass fiber reinforced plastic correction device and method, comprising a top plate 1, a pressure block 3, a positioning plate 4 and a heating plate 5, wherein the four ends of the bottom of the top plate 1 are welded to the top of a support rod 6, the support rod 6 is provided with four, and the bottoms of the four support rods 6 are welded to a bottom plate 7, a hydraulic rod 2 is installed at the bottom of the top plate 1, and the telescopic end of the bottom of the hydraulic rod 2 is welded to the top of the pressure block 3, two pressure blocks 3 are provided, and the two pressure blocks 3 are arranged above the positioning plate 4, the four ends of the positioning plate 4 are sleeved on the outside of the support rod 6, and the support rod 6 is welded to the positioning plate 4, a heating plate 5 is provided below the positioning plate 4, and the top of the heating plate 5 is tightly fitted with the positioning plate 4, and the heating plate 5 is provided below the positioning plate 4. A heating coil is provided inside the hot plate 5, and the product is placed inside the positioning groove 8 so that the product can be embedded in the positioning groove 8 for fixation. The heating plate 5 is connected to an external heating power source, and the positioning plate 4 is slowly heated by the heating of the heating plate 5. The positioning plate 4 is heated up while the product is heated up. The telescopic ends of the hydraulic rod 2 are synchronously extended and retracted, so that the hydraulic rod 2 can drive the pressing block 3 to move up and down. The pressing block 3 moves downward, so that the two ends of the pressing block 3 can press down with the warped parts of the two ends of the glass fiber reinforced plastic product, thereby performing a curing treatment. After such a treatment, the curing can be complete and the product can maintain the stability of size and structure.

[0042] The pressing block 3 is arranged in a U shape. The pressing block 3 is arranged above the positioning groove 8. The positioning groove 8 is opened on the top surface of the positioning plate 4. There are two positioning grooves 8, and the two positioning grooves 8 are arranged in parallel.

[0043] The heating coils inside the heating plate 5 are distributed in a multi-bend shape, and the contact surface between the heating plate 5 and the positioning plate 4 is a copper plate.

[0044] The shape of the positioning groove 8 on the surface of the positioning plate 4 matches the shape of the FRP product. The depth of the positioning groove 8 is less than the thickness of the FRP product. The top of the FRP product protrudes from the upper surface of the positioning plate 4 .

[0045] Embodiment 2:

[0046] The correction steps of using high silica fiber magnesium phenolic premix composite fiberglass are as follows:

[0047] S1: After the product is solidified to a certain strength, it is demoulded. The mold consists of three parts: upper, middle and lower. The demoulding method is to open the upper mold first, and then disassemble the middle mold and the lower mold. At this time, the product is fixed on the middle mold. The mold is knocked by a rubber hammer through the manual demoulding method. Due to the vibration, the FRP product is separated from the mold;

[0048] S2: After demoulding, the product needs to be processed in time to remove burrs and burrs, repair surface and internal defects, and the mold shrinkage rate, sealing, demoulding angle, surface finish, mold strength, rigidity, and wear resistance must meet the design requirements;

[0049] S3: After molding and demoulding, the product should be placed for 24 hours before heating and curing. The product is placed in the positioning groove 8 so that the product can be embedded in the positioning groove 8 for fixation. The heating plate 5 is connected to the external heating power supply. The positioning plate 4 is slowly heated by the heating plate 5. The positioning plate 4 is heated up while the product is heated up.

[0050] S4: The telescopic end of the hydraulic rod 2 is synchronously extended and retracted, so that the hydraulic rod 2 can drive the pressing block 3 to move up and down. The pressing block 3 moves downward, so that the two ends of the pressing block 3 can press down the warped parts of the two ends of the glass fiber reinforced plastic product, thereby performing a curing process.

[0051] The temperature at which the heating plate 5 heats and cures the positioning plate 4 in S3 is slightly lower than the resin thermal deformation temperature of 80°C, and then the curing treatment is carried out at this temperature for 4 hours, with a heating rate of 10°C / h.

[0052] In S3, the glass fiber reinforced plastic product should be heated evenly to avoid local overheating, and during the heating process, a hot air blower is used to blow hot air to the surface of the product to heat it, thereby reducing the temperature difference between the inside and outside of the glass fiber reinforced plastic product.

[0053] The bottom pressure surface of the pressing block 3 should be kept flat, and the bottom pressure surface of the pressing block 3 should be kept parallel to the horizontal plane when pressing downward to avoid uneven force on both ends of the glass fiber reinforced plastic product during the pressing process.

[0054] When the FRP product is bent upward, the upper surface temperature needs to be appropriately lowered, and no auxiliary heating is required through a blast device during the heating process. When it is bent downward, the lower surface temperature needs to be appropriately lowered and the upper surface temperature needs to be increased, and a blast device is used to perform auxiliary heating through hot air flow.

[0055] Embodiment 3:

[0056] The correction steps of using high silica fiber magnesium phenolic premix composite fiberglass are as follows:

[0057] S1: After the product is solidified to a certain strength, it is demoulded. The mold consists of three parts: upper, middle and lower. The demoulding method is to open the upper mold first, and then disassemble the middle mold and the lower mold. At this time, the product is fixed on the middle mold. The mold is knocked by a rubber hammer through the manual demoulding method. Due to the vibration, the FRP product is separated from the mold;

[0058] S2: After demoulding, the product needs to be processed in time to remove burrs and burrs, repair surface and internal defects, and the mold shrinkage rate, sealing, demoulding angle, surface finish, mold strength, rigidity, and wear resistance must meet the design requirements;

[0059] S3: After molding and demoulding, the product should be placed for 24 hours before heating and curing. The product is placed in the positioning groove 8 so that the product can be embedded in the positioning groove 8 for fixation. The heating plate 5 is connected to the external heating power supply. The positioning plate 4 is slowly heated by the heating plate 5. The positioning plate 4 is heated up while the product is heated up.

[0060] S4: The telescopic end of the hydraulic rod 2 is synchronously extended and retracted, so that the hydraulic rod 2 can drive the pressing block 3 to move up and down. The pressing block 3 moves downward, so that the two ends of the pressing block 3 can press down the warped parts of the two ends of the glass fiber reinforced plastic product, thereby performing a curing process.

[0061] In the above S3, the temperature at which the heating plate 5 heats and cures the positioning plate 4 is slightly lower than the thermal deformation temperature of the resin, 100°C. The plate is then cured at this temperature for 8 hours, with a heating rate of 10°C / h.

[0062] In S3, the glass fiber reinforced plastic product should be heated evenly to avoid local overheating, and during the heating process, a hot air blower is used to blow hot air to the surface of the product to heat it, thereby reducing the temperature difference between the inside and outside of the glass fiber reinforced plastic product.

[0063] The bottom pressure surface of the pressing block 3 should be kept flat, and the bottom pressure surface of the pressing block 3 should be kept parallel to the horizontal plane when pressing downward to avoid uneven force on both ends of the glass fiber reinforced plastic product during the pressing process.

[0064] When the FRP product is bent upward, the upper surface temperature needs to be appropriately lowered, and no auxiliary heating is required through a blast device during the heating process. When it is bent downward, the lower surface temperature needs to be appropriately lowered and the upper surface temperature needs to be increased, and a blast device is used to perform auxiliary heating through hot air flow.

[0065] Working principle: When correcting the product, the product is placed in the positioning groove 8 so that the product can be embedded in the positioning groove 8 for fixing, and the heating plate 5 is connected to the external heating power supply. The positioning plate 4 is slowly heated by the heating of the heating plate 5. The positioning plate 4 is heated while the product is heated. The telescopic end of the hydraulic rod 2 is synchronously extended and retracted so that the hydraulic rod 2 can drive the pressing block 3 to move up and down. The pressing block 3 moves downward so that the two ends of the pressing block 3 can press down on the warped parts of the glass fiber reinforced plastic product at both ends, thereby performing a curing treatment. After such a treatment, the curing can be complete and the product can maintain the stability of size and structure, thereby solving the problems of inconsistent product thickness, differences in shrinkage stress in various regions, and changes in shape and size of the product caused by the release of residual stress.

[0066] The components of the present invention, 1. top plate; 2. hydraulic rod; 3. pressure block; 4. positioning plate; 5. heating plate; 6. support rod; 7. bottom plate; 8. positioning groove, are all universal standard parts or components known to those skilled in the art, and their structures and principles can be known to those skilled in the art through technical manuals or conventional experimental methods.

[0067] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A glass fiber reinforced plastic correction device, characterized in that: It comprises a top plate (1), a pressing block (3), a positioning plate (4) and a heating plate (5); the four ends of the bottom of the top plate (1) are welded to the tops of four support rods (6), and the bottoms of the four support rods (6) are welded to the bottom plate (7); the four ends of the positioning plate (4) are sleeved on the outside of the support rods (6), and the support rods (6) are welded to the positioning plate (4); a heating plate (5) is arranged below the positioning plate (4), the top of the heating plate (5) is tightly fitted to the positioning plate (4), and a heating coil is arranged inside the heating plate (5); Four hydraulic rods (2) are installed at the bottom of the top plate (1), and two pressure blocks (3) are arranged below the four hydraulic rods (2); the telescopic ends at the bottom of each of the two hydraulic rods (2) are welded to the top of a pressure block (3); the two lower end surfaces of the two pressure blocks (3) are fixedly connected to the upper surface of the positioning plate (4); the pressure blocks (3) are in an inverted U shape; two positioning grooves (8) are also arranged on the upper surface of the positioning plate (4), and the two positioning grooves (8) are arranged in parallel; the middle part of the pressure block (3) is arranged above the positioning groove (8).

2. A glass fiber reinforced plastic correction device according to claim 1, characterized in that: The heating coils inside the heating plate (5) are distributed in a multi-bend shape, and the contact surface between the heating plate (5) and the positioning plate (4) is a copper plate.

3. A glass fiber reinforced plastic correction device according to claim 1, characterized in that: The shape of the positioning groove (8) on the surface of the positioning plate (4) matches the shape of the glass fiber reinforced plastic product, the depth of the positioning groove (8) is less than the thickness of the glass fiber reinforced plastic product, and the top of the glass fiber reinforced plastic product protrudes from the upper surface of the positioning plate (4).

4. A method for straightening glass fiber reinforced plastics, using a glass fiber reinforced plastics straightening device according to claims 1-3, characterized in that: The steps are as follows: Step 1: After the product is solidified to a certain strength, it is demoulded. The mold consists of three parts: upper, middle and lower. The demoulding method is to open the upper mold first, and then disassemble the middle mold and the lower mold. At this time, the product is fixed on the middle mold. The mold is knocked by a rubber hammer through the manual demoulding method. Due to the vibration, the fiberglass product is separated from the mold; Step 2: After demoulding, the product needs to be processed in time to remove burrs and burrs, repair surface and internal defects, and the mold shrinkage rate, sealing, demoulding angle, surface finish, mold strength, rigidity, and wear resistance must meet the design requirements; Step 3: After molding and demoulding, the product should be placed for 24 hours before being heated and cured. The product is placed inside the positioning groove (8) so that the product can be embedded in the positioning groove (8) and fixed. The heating plate (5) is connected to an external heating power source. The positioning plate (4) is slowly heated by the heating plate (5). When the positioning plate (4) is heated, the product is heated at the same time. Step 4: The telescopic end of the hydraulic rod (2) is synchronously extended and retracted so that the hydraulic rod (2) can drive the pressing block (3) to move up and down. The pressing block (3) moves downward so that the two ends of the pressing block (3) can press down the warped parts of the glass fiber reinforced plastic product at both ends, thereby performing a curing process.

5. A glass fiber reinforced plastic correction method according to claim 1, characterized in that: In the step 3, the temperature at which the heating plate (5) heats and cures the positioning plate (4) is slightly lower than the thermal deformation temperature of the resin, 80°C-100°C, and then the curing treatment is carried out at this temperature for 4-8 hours, with a heating rate of 10°C / h.

6. A method for correcting glass fiber reinforced plastics according to claim 5, characterized in that: In the step 3, the FRP product should be heated evenly to avoid local overheating, and during the heating process, a hot air blower is used to blow hot air to the surface of the product to heat it, thereby reducing the temperature difference between the inside and outside of the FRP product.

7. A glass fiber reinforced plastic correction device and method according to claim 5, characterized in that: The bottom pressure surface of the pressing block (3) should be kept flat, and the bottom pressure surface of the pressing block (3) should be kept parallel to the horizontal plane when pressing downward, so as to avoid uneven force on both ends of the glass fiber reinforced plastic product during the pressing process.

8. A glass fiber reinforced plastic correction device and method according to claim 5, characterized in that: When the FRP product is bent upward, the upper surface temperature needs to be appropriately lowered, and no auxiliary heating is required through a blast device during the heating process. When it is bent downward, the lower surface temperature needs to be appropriately lowered and the upper surface temperature needs to be increased, and a blast device is used to perform auxiliary heating through hot air flow.

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