Drilling method for alternative drilling flange

Abstract

The invention relates to the technical field of offshore construction of a Taiwan flange, and discloses a drilling method for the Taiwan flange, which comprises the following steps of: S1, supporting and fixing: supporting the Taiwan flange by adopting a four-point elastic supporting system, and fixing the Taiwan flange by adopting a split type hydraulic clamp; step S2, workpiece positioning; s3, workpiece drilling is conducted; step S4, vibration suppression; s5, controlling residual stress; and S6, carrying out precision acceptance. According to the alternative drilling flange drilling method, a laser projector is adopted for pre-marking hole sites, a three-stage stepped drilling technology including pre-drilling, hole expanding and fine trimming is adopted, a hydraulic active vibration reduction platform and a multi-stage vibration suppression system of a tool damping sleeve are used in a matched mode, and residual stress control measures such as low-temperature annealing are adopted; the problems that deformation, insufficient hole site precision and hidden damage are prone to occurring in the deep hole machining process of the large-size replacement flange are avoided, and finally it is ensured that key precision indexes such as the hole diameter, the hole distance and the perpendicularity comprehensively meet the design requirements.

Description

Technical Field

[0001] This invention relates to the field of replacement flange technology in marine construction, specifically a method for drilling holes in replacement flanges. Background Technology

[0002] As the offshore wind power industry develops towards deeper water and larger scale, the diameter of monopile foundations has exceeded 7.5 meters. As the core energy transfer component between the pile hammer and the monopile, the replacement flange is crucial. During offshore wind power construction, the enormous impact energy generated by the pile hammer needs to be accurately and efficiently transferred to the monopile through the replacement flange to ensure that the monopile can be successfully driven into the predetermined position on the seabed. Therefore, the manufacturing and modification quality of the replacement flange is directly related to the structural safety and construction efficiency of the entire wind power facility. Industry data shows that in 2023, monopile foundations accounted for as much as 68% of the newly installed offshore wind power capacity worldwide, and construction accidents caused by replacement flange failure accounted for about 17% of foundation failures.

[0003] During the modification of replacement flanges, especially in the support of large workpieces, high-precision hole group processing, vibration control and residual stress management, there is still a lack of systematic process methods. This leads to the replacement flanges being prone to deformation, insufficient hole position accuracy and hidden damage during processing. Once the replacement flange fails, it may cause deviation in the verticality of the pile driving, resulting in the single pile foundation failing to meet the design requirements. In severe cases, it may even cause the entire wind power facility to be structurally unstable, which will greatly affect the safe operation and service life of the offshore wind farm. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for drilling holes in a flange, which solves the problems mentioned in the background.

[0005] This invention provides the following technical solution: a method for drilling holes in a flange, comprising the following steps:

[0006] Step S1, Support and Fixing Step: The replacement flange is supported by a four-point elastic support system and fixed by a split hydraulic clamp.

[0007] Step S2, workpiece positioning: Use a laser projector to mark the pre-marked hole positions on the flange;

[0008] Step S3, Drilling the workpiece: Drilling the replacement flange using a stepped drilling process, which includes a pre-drilling stage, a reaming stage, and a finishing stage.

[0009] Step S4, Vibration Suppression: During the drilling process, a multi-stage vibration suppression system is applied to reduce the vibration of the worktable. The multi-stage vibration suppression system includes a hydraulic active vibration damping platform and a tool vibration damping device.

[0010] Step S5, Residual Stress Control: Controlling residual stress includes performing low-temperature annealing, optimizing cutting parameters, and selecting cutting tools and cutting fluids;

[0011] Step S6, accuracy acceptance: hole diameter accuracy acceptance, hole position accuracy acceptance, and hole perpendicularity acceptance.

[0012] Preferably, in step S1, the four-point elastic support system includes four 20t-class radial support arms, and the support points of the four radial support arms are located at the four corners of a rectangle, the diagonal length of which is 7.5 meters.

[0013] Furthermore, each support arm has a polyurethane or metal composite gasket laid on the contact surface with the workpiece, wherein the hardness of the polyurethane layer is 80-95 Shore A.

[0014] Preferably, in step S1, the number of split hydraulic clamps is four, and the four split hydraulic clamps are symmetrically connected to the replacement flange in a cross-shaped layout. The four split hydraulic clamps are controlled by closed loop to keep the clamping force at 12±0.5MPa and the levelness error ≤0.05mm / m.

[0015] The four split hydraulic clamps and the four radial support arms are arranged alternately at intervals in the circumferential direction.

[0016] Preferably, in step S2, the accuracy of the pre-marked hole position of the laser projector is ±0.2mm.

[0017] Preferably, step S3 includes:

[0018] Step S31, Pre-drilling stage: During the drilling stage, a 30mm diameter carbide cold drill is used with a rotation speed of 80-100rpm and a feed rate of 0.15mm / rev, and 8% emulsion is used for cooling.

[0019] Step S32, Hole Enlargement Stage: In the hole enlargement stage, a coated reamer with a diameter of 60mm is used, with a rotation speed of 60-80rpm and a feed rate of 0.10mm / rev, and external spray cooling is adopted.

[0020] Step S33, finishing stage: The finishing stage uses a PCD step drill with a diameter of 69mm, a rotation speed of 40-50rpm, a feed rate of 0.05mm / rev, and is cooled with high-penetration cutting oil.

[0021] Preferably, the hydraulic active vibration damping platform is installed below the workbench of the processing equipment. It monitors the vibration of the workbench in real time through sensors, adjusts the output of the hydraulic system according to the feedback signal, and generates a force opposite to the vibration direction to counteract the vibration.

[0022] Preferably, the tool vibration damping device includes a damping sleeve, which is installed on the drill bit to suppress vibrations generated during cutting through damping dissipation.

[0023] Preferably, in step S5, optimizing the cutting parameters includes appropriately reducing the cutting speed and increasing the feed rate to reduce the cutting force.

[0024] Preferably, in step S6, the acceptance criteria for aperture accuracy are: aperture tolerance of H7 to H10.

[0025] Acceptance criteria for hole position accuracy: hole spacing tolerance is ±0.3~±0.5mm, and the angular deviation of circumferentially distributed holes is ≤0.5°;

[0026] Acceptance criteria for hole perpendicularity: The perpendicularity tolerance of the hole axis to the end face of the flange is 0.1~0.2mm / 100mm.

[0027] Preferably, the hole diameter accuracy is inspected using a plug gauge, the hole position accuracy is inspected using a coordinate measuring machine or scribing machine, and the hole perpendicularity is inspected using a combination of a dial indicator and a mandrel or a combination of a right-angle ruler and a feeler gauge.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. This invention, by setting up a three-stage stepped drilling process including pre-drilling, reaming, and finishing using a laser projector to pre-mark hole positions, and by applying a multi-stage vibration suppression system with a hydraulic active vibration reduction platform, a tool damping sleeve, and residual stress control measures such as low-temperature annealing, avoids deformation, insufficient hole position accuracy, and hidden damage that may occur during deep hole machining of large-size replacement flanges. Ultimately, it ensures that key accuracy indicators such as hole diameter, hole spacing, and perpendicularity fully meet the design requirements.

[0030] 2. This invention provides uniform, stable, and buffering support and fixation for large replacement flanges by setting up a four-point elastic support system and using a split hydraulic clamp to fix the replacement flange. This effectively solves the technical problem that the workpiece is prone to displacement or plastic deformation during processing due to uneven clamping force or insufficient rigid support. Attached Figure Description

[0031] Figure 1 This is a flowchart of the present invention;

[0032] Figure 2 This is a schematic diagram of the distribution structure of the support arm and the split hydraulic clamp of the present invention.

[0033] In the diagram: 1. Replacement flange; 2. Support arm; 3. Split-type hydraulic clamp. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Please see Figure 1-2 A method for drilling holes in a flange, comprising the following steps:

[0036] Step S1, Support and Fixing Step: The replacement flange 1 is supported by a four-point elastic support system, and the replacement flange 1 is fixed by a split hydraulic clamp 3.

[0037] Step S2, workpiece positioning: Use a laser projector to mark the hole positions of flange 1;

[0038] Step S3, Drilling the workpiece: Drilling the replacement flange 1 using a stepped drilling process, which includes a pre-drilling stage, a reaming stage, and a finishing stage.

[0039] Step S4, Vibration Suppression: During the drilling process, a multi-stage vibration suppression system is applied to reduce table vibration. The multi-stage vibration suppression system includes a hydraulic active vibration damping platform and a tool vibration damping device.

[0040] Step S5, Residual Stress Control: Controlling residual stress includes performing low-temperature annealing, optimizing cutting parameters, and selecting cutting tools and cutting fluids;

[0041] Step S6, accuracy acceptance: hole diameter accuracy acceptance, hole position accuracy acceptance, and hole perpendicularity acceptance.

[0042] Please see Figure 2 In step S1, the four-point elastic support system includes four 20t-class radial support arms 2, and the support points of the four radial support arms 2 are located at the four corners of a rectangle with a diagonal length of 7.5 meters.

[0043] Furthermore, each support arm 2 has a polyurethane or metal composite gasket laid on the contact surface with the workpiece, wherein the hardness of the polyurethane layer is 80-95 Shore A.

[0044] In step S1, there are four split hydraulic clamps 3. The four split hydraulic clamps 3 are symmetrically connected to the replacement flange 1 in a cross-shaped layout. The four split hydraulic clamps 3 are controlled by closed loop to keep the clamping force at 12±0.5MPa and the levelness error ≤0.05mm / m.

[0045] Four separate hydraulic clamps 3 and four radial support arms 2 are arranged alternately in the circumferential direction.

[0046] In step S2, the accuracy of the pre-marked hole position of the laser projector is ±0.2mm.

[0047] Step S3 includes:

[0048] Step S31, Pre-drilling stage: During the drilling stage, a 30mm diameter carbide cold drill is used with a rotation speed of 80-100rpm and a feed rate of 0.15mm / rev, and 8% emulsion is used for cooling.

[0049] Step S32, Hole Enlargement Stage: In the hole enlargement stage, a coated reamer with a diameter of 60mm is used, with a rotation speed of 60-80rpm and a feed rate of 0.10mm / rev, and external spray cooling is adopted.

[0050] Step S33, finishing stage: The finishing stage uses a 69mm diameter PCD step drill with a rotation speed of 40-50rpm and a feed rate of 0.05mm / rev. It is cooled with high-penetration cutting oil. The PCD step drill is a step-shaped drill bit made of polycrystalline diamond material and is mainly used for high-speed machining of materials such as aluminum and composite materials.

[0051] The hydraulic active vibration damping platform is installed under the workbench of the processing equipment. It monitors the vibration of the workbench in real time through sensors and adjusts the output of the hydraulic system according to the feedback signal to generate a force opposite to the vibration direction to counteract the vibration.

[0052] The tool vibration reduction device includes a damping sleeve, which is installed on the drill bit to suppress the vibration generated during cutting through damping dissipation.

[0053] In step S5, optimizing cutting parameters includes appropriately reducing the cutting speed and increasing the feed rate to reduce the cutting force.

[0054] In step S6, the acceptance criteria for aperture accuracy are: aperture tolerance is H7~H10.

[0055] Acceptance criteria for hole position accuracy: hole spacing tolerance is ±0.3~±0.5mm, and the angular deviation of circumferentially distributed holes is ≤0.5°;

[0056] Acceptance criteria for hole perpendicularity: The perpendicularity tolerance of the hole axis to the end face of the flange is 0.1~0.2mm / 100mm.

[0057] Among them, the hole diameter accuracy is inspected using a plug gauge, the hole position accuracy is inspected using a coordinate measuring machine or scribing, and the hole perpendicularity is inspected using a combination of a dial indicator and a mandrel or a combination of a right-angle ruler and a feeler gauge.

[0058] During construction, the replacement flange 1 workpiece is supported and fixed using a four-point elastic support system: four 20t-class radial support arms 2 are arranged diagonally at 7.5m. The top of the support arms 2 is covered with metal composite gaskets or polyurethane layers with a hardness gradient of 80-95 Shore A to absorb micro-deformation, provide stable support for the replacement flange 1, buffer micro-deformation, and ensure processing stability.

[0059] To increase the stability of the replacement flange 1 workpiece, the number of radial support arms 2 can be set to more than four.

[0060] Four split hydraulic clamps 3 are symmetrically connected to the replacement flange 1 in a cross-shaped layout. Through closed-loop control, the clamping force is maintained at 12±0.5MPa, and the levelness error is ≤0.05mm / m. They can be flexibly adjusted to adapt to the shape and size of the workpiece, providing a uniform and stable clamping force to prevent displacement or deformation of the workpiece during processing.

[0061] Replacement flange 1 workpiece positioning: Laser projector pre-marks hole positions with an accuracy of ±0.2mm. The designed hole position information is accurately projected onto the workpiece surface, providing an accurate position reference for subsequent drilling and improving the accuracy of hole positioning.

[0062] Replacement flange 1-step drilling process:

[0063] Pre-drilling stage: Select a 30mm diameter carbide cold drill, spindle speed 80-100rpm, feed rate 0.15mm / rev, and use 8% emulsion for cooling. Drill with a smaller diameter drill bit, lower cutting speed and feed rate to form a preliminary hole, laying the foundation for hole enlargement and reducing the cutting force and vibration generated by direct drilling with a large diameter drill bit.

[0064] Enlarging stage: Use a 60mm diameter coated reamer at a speed of 60-80 rpm and a feed rate of 0.10mm / rev, with external spray cooling. Replace with a larger diameter drill bit and appropriately increase the cutting speed and feed rate to gradually enlarge the hole to near the design size. Parameters need to be adjusted according to the workpiece material and machining conditions to ensure reaming accuracy and efficiency.

[0065] Finishing stage: Use a 69mm diameter PCD step drill, spindle speed 40-50rpm, feed rate 0.05mm / rev, use high-penetration cutting oil for cooling, and finish the hole with low cutting speed and small feed rate to ensure that the hole's dimensional accuracy, roundness and surface roughness meet the design requirements.

[0066] Replacement flange 1 multi-stage vibration suppression system:

[0067] The hydraulic active vibration damping platform is installed under the worktable of the processing equipment. It monitors the vibration of the worktable in real time through sensors, and adjusts the output of the hydraulic system according to the feedback signal to generate a force opposite to the vibration direction to counteract the vibration, reduce the vibration amplitude, and improve the processing accuracy and surface quality.

[0068] A tool vibration damping device is installed on the drill bit, such as a damping sleeve. The damping sleeve is installed on the drill bit to suppress the vibration generated during cutting through damping dissipation, thereby reducing tool vibration, extending tool life, and improving drilling accuracy and surface quality.

[0069] Residual stress control for replacement flange 1: Low-temperature annealing is used to reduce initial residual stress, and cutting parameters are optimized, such as appropriately reducing the cutting speed, increasing the feed rate, and reducing the cutting force to reduce residual stress generation. Suitable tools and cutting fluids are selected to improve cutting conditions and reduce residual stress.

[0070] Acceptance test of the accuracy of the replacement flange with one hole:

[0071] Acceptance criteria for bore diameter accuracy: The bore diameter tolerance is usually H7~H10, such as φ50H8 with a tolerance of +0.039 / 0mm, as per the drawing requirements.

[0072] Inspection method: Plug gauge inspection, the go gauge must pass through the hole completely, the no-go gauge must not pass through; Vernier caliper / micrometer measures once in the axial direction and once in the radial vertical direction of the hole, and take the average value. The deviation must be within the tolerance range.

[0073] Acceptance criteria for hole position accuracy: hole spacing tolerance is usually ±0.3~±0.5mm, and the angular deviation of circumferentially distributed holes is ≤0.5°.

[0074] Inspection methods: The coordinate measuring machine uses the flange end face or bolt holes as a reference to measure the coordinate values ​​of each hole and calculate the hole distance and angle deviation; the scribing inspection uses a height gauge to scribing on the flange end face and compares the hole position with the reference line deviation, which is suitable for scenarios with low precision requirements.

[0075] Hole verticality acceptance: The acceptance criteria are as follows: The perpendicularity tolerance of the hole axis to the end face of the flange is usually 0.1 to 0.2 mm / 100 mm. If the hole depth is 100 mm, the deviation is ≤0.2 mm.

[0076] Test method: Dial indicator and mandrel. Insert the mandrel into the hole, with the dial indicator contact against the end face of the mandrel. Rotate the flange one revolution and read the pointer swing range to calculate the perpendicularity error.

[0077] Use a right-angle ruler and feeler gauge. Place the right-angle ruler against the end face of the flange and measure the gap between the mandrel and the right-angle ruler. The maximum value of the gap is the perpendicularity deviation.

[0078] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for drilling holes in a flange, characterized in that, Includes the following steps: Step S1, Support and Fixing Step: The replacement flange (1) is supported by a four-point elastic support system and fixed by a split hydraulic clamp (3); Step S2, workpiece positioning: Use a laser projector to pre-mark the hole positions of the flange (1); Step S3, workpiece drilling: The step drilling process is used to drill the replacement flange (1), which includes a pre-drilling stage, a hole enlargement stage and a finishing stage. Step S4, Vibration Suppression: During the drilling process, a multi-stage vibration suppression system is applied to reduce the vibration of the worktable. The multi-stage vibration suppression system includes a hydraulic active vibration damping platform and a tool vibration damping device. Step S5, Residual Stress Control: Controlling residual stress includes performing low-temperature annealing, optimizing cutting parameters, and selecting cutting tools and cutting fluids; Step S6, accuracy acceptance: hole diameter accuracy acceptance, hole position accuracy acceptance, and hole perpendicularity acceptance.

2. The method for drilling holes in a flange according to claim 1, characterized in that, In step S1, the four-point elastic support system includes four 20t-class radial support arms (2), and the support points of the four radial support arms (2) are located at the four corners of a rectangle with a diagonal length of 7.5 meters. Furthermore, each support arm (2) is covered with a polyurethane or metal composite gasket on its contact surface with the workpiece, wherein the hardness of the polyurethane layer is 80-95 Shore A.

3. The method for drilling holes in a flange according to claim 2, characterized in that, In step S1, there are four split hydraulic clamps (3). The four split hydraulic clamps (3) are symmetrically connected to the replacement flange (1) in a cross-shaped layout. The four split hydraulic clamps (3) are controlled by closed loop to keep the clamping force at 12±0.5MPa and the levelness error ≤0.05mm / m. The four split hydraulic clamps (3) and the four radial support arms (2) are arranged alternately in the circumferential direction.

4. The method for drilling holes in a flange according to claim 1, characterized in that, In step S2, the accuracy of the pre-marked hole position of the laser projector is ±0.2mm.

5. The method for drilling holes in a flange according to claim 1, characterized in that, Step S3 includes: Step S31, Pre-drilling stage: During the drilling stage, a 30mm diameter carbide cold drill is used with a rotation speed of 80-100rpm and a feed rate of 0.15mm / rev, and 8% emulsion is used for cooling. Step S32, Hole Enlargement Stage: In the hole enlargement stage, a coated reamer with a diameter of 60mm is used, with a rotation speed of 60-80rpm and a feed rate of 0.10mm / rev, and external spray cooling is adopted. Step S33, finishing stage: The finishing stage uses a PCD step drill with a diameter of 69mm, a rotation speed of 40-50rpm, a feed rate of 0.05mm / rev, and is cooled with high-penetration cutting oil.

6. The method for drilling holes in a replacement flange according to claim 1, characterized in that, The hydraulic active vibration damping platform is installed under the workbench of the processing equipment. It monitors the vibration of the workbench in real time through sensors and adjusts the output of the hydraulic system according to the feedback signal to generate a force opposite to the vibration direction to counteract the vibration.

7. The method for drilling holes in a replacement flange according to claim 1, characterized in that, The tool vibration reduction device includes a damping sleeve, which is installed on the drill bit to suppress the vibration generated during cutting through damping dissipation.

8. The method for drilling holes in a replacement flange according to claim 1, characterized in that, In step S5, optimizing cutting parameters includes appropriately reducing the cutting speed and increasing the feed rate to reduce the cutting force.

9. The method for drilling holes in a replacement flange according to claim 1, characterized in that, In step S6, the acceptance criteria for aperture accuracy are: aperture tolerance is H7~H10. Acceptance criteria for hole position accuracy: hole spacing tolerance is ±0.3~±0.5mm, and the angular deviation of circumferentially distributed holes is ≤0.5°; Acceptance criteria for hole perpendicularity: The perpendicularity tolerance of the hole axis to the end face of the flange is 0.1~0.2mm / 100mm.

10. The method for drilling holes in a flange according to claim 1, characterized in that, The hole diameter accuracy is inspected using a plug gauge; the hole position accuracy is inspected using a coordinate measuring machine or scribing; and the hole perpendicularity is inspected using a combination of a dial indicator and a mandrel or a combination of a right-angle ruler and a feeler gauge.

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