Cleaning method for U-shaped bolt

Abstract

The invention discloses a cleaning method of a U-shaped bolt, which realizes efficient, environment-friendly and damage-free cleaning through the synergistic effect of biological enzymolysis, eddy current pulse rust removal and gas-solid flow scouring in combination with a 5-degree inclined self-adaptive clamp. The clamp adopts arc-shaped groove indexing locking and modular chuck design, is adaptive to bolts of multiple specifications, and is convenient to remodel and stable in precision.

Description

Technical Field

[0001] The present invention relates to the technical field of bolt production, and particularly to a cleaning method for U-bolts. Background Art

[0002] In the field of metal component cleaning, as a typical complex-structured part, U-bolts have long faced multiple technical challenges in their cleaning process. A U-bolt consists of a U-shaped bending part, a threaded section, and an end part. The special geometric shape leads to significant limitations in traditional cleaning methods, which are specifically manifested in the following aspects: Difficult to cover cleaning dead corners In the U-shaped bending part and threaded gaps of U-bolts, cleaning blind spots are likely to form. Due to the limitations of fluid dynamics characteristics, conventional soaking or spraying processes cannot effectively remove the accumulated oil stains, rust layers, and particulate impurities inside. Especially in the threaded meshing area, residues can easily lead to a decrease in assembly accuracy or even failure.

[0003] Environmental and material compatibility issues of chemical cleaning agents Although existing acidic or alkaline cleaning agents can remove rust, they are likely to cause corrosion to the bolt base material. Especially for bolts made of high-carbon steel, hydrogen embrittlement is likely to occur on the surface. In addition, the residues of chemical reagents require multiple rinsing processes, increasing the cost of wastewater treatment and not meeting the requirements of green manufacturing.

[0004] Risk of precision damage in mechanical cleaning When using physical cleaning methods such as wire brushes or sandblasting, the threaded surface is easily scratched or dimensional deviations occur (the error often exceeds 0.05 mm), directly affecting the mechanical properties and service life of the bolts. For high-precision connection scenarios (such as the flange connection of a wind turbine tower), such damage may lead to major safety hazards.

[0005] Low efficiency in step-by-step treatment of multiple pollutants Oil stains, rust layers, and particulate matter usually need to be treated in stages. The traditional process lacks a synergistic mechanism, resulting in a long cleaning cycle (the single-piece processing time ≥ 20 minutes) and high energy consumption. For example, the series process of first chemical degreasing and then mechanical derusting not only occupies a large area of equipment but also increases the risk of secondary pollution on the bolt surface due to multiple clamping.

[0006] Insufficient fixture adaptability Existing fixtures mostly use fixed-angle clamping, which is difficult to meet the requirement of adjusting the opening direction of U-bolts, resulting in the accumulation of cleaning liquid in the U-shaped area. In addition, the clamping force control accuracy is low (the error > ±10%), which is likely to cause thread deformation or insecure clamping.

[0007] In view of the above problems, the industry urgently needs an efficient, environmentally friendly and non-destructive U-bolt cleaning solution that can achieve the synergistic effect of oil decomposition, rust layer stripping and particle removal in a single system, and is equipped with an adaptive fixture to improve process stability and versatility. Summary of the Invention

[0008] In order to overcome the above defects of the prior art, an embodiment of the present invention provides a cleaning method for U-bolts.

[0009] To achieve the above object, the innovative points of the present invention are as follows: Specifically, it includes the following steps: S1. Bioenzymatic oil decomposition stage: Spray a composite bioenzyme cleaning solution at 40-50°C on the surface of the U-bolt to decompose grease and organic matter; S2. Eddy current pulse rust removal stage: Immerse the bolt in an eddy current tank containing an acidic solution, and simultaneously apply a high-frequency pulse current of 20-40 kHz and a rotating magnetic field to strip the rust layer and directionally collect rust particles; S3. Gas-solid two-phase flow scouring stage: Impact the surface of the bolt with a mixed flow of high-pressure air and nano-ceramic particles to remove residual particles.

[0010] Further, in step S1, the composite bioenzyme cleaning solution contains lipase and protease, with a pH value of 8-9, a spraying pressure of 0.5-1 MPa, a duration of 3-5 minutes, and a metal corrosion inhibitor with a mass fraction of 0.1-0.5% is added to the cleaning solution.

[0011] Further, in step S2, the acidic solution is a mixed solution of citric acid and phytic acid, with a pH value of 3-4, a rotating magnetic field intensity of 0.2-0.5 T, and a pulse current frequency of 25-35 kHz.

[0012] Further, in step S3, the high-pressure air pressure is 2-3 MPa, the nano-ceramic particle diameter is 50-100 μm, the hardness is lower than that of the bolt substrate, and the spraying direction is inclined at an angle of 20-40° to the bolt axis.

[0013] Further, a pretreatment operation is also included before step S1: Fix the U-bolt with a fixture with an adjustable fixed angle, make its U-shaped opening inclined downward, the clamping force of the fixture is 100-300 N, and it is adapted to different bolt specifications.

[0014] Further, a post-treatment operation is also included after the above step S3: Rinse with ultrasonic vibration deionized water with a frequency of 28-35 kHz, then dry under a vacuum degree ≤ 10 Pa, and spray a graphene-based water-based rust-proof film with a thickness ≤ 5 μm.

[0015] Further, the inclination angle of the U-shaped opening is 5°.

[0016] Further, the fixture includes a base and a jaw cylinder. The bottom of the base is respectively provided with an arc groove and a dividing plate. The dividing plate is coaxially arranged at the center of the arc groove. A substrate is provided on the jaw cylinder, and the substrate is slidably arranged inside the arc groove and fixed to the dividing plate through a positioning pin. The output end of the jaw cylinder is provided with a jaw arm, and a detachable chuck is provided on the jaw arm. The chuck is provided with a V-shaped groove matching the outer diameter of the U-bolt.

[0017] Further, the dividing plate is evenly distributed with 7 dividing holes, and the corresponding angles are -15°, -10°, -5°, 0°, +5°, +10°, +15°. The diameter of the dividing hole is φ8H7. The positioning pin is a spring-loaded tapered pin with a taper of 1:50 and is surface nitrided.

[0018] The beneficial effects of the present invention are as follows: 1. The cleaning effect is significantly improved Cleaning without dead corners: The synergistic effect of high-pressure injection (0.5 - 1 MPa) of bio-enzymolysis solution and inclined scouring (20 - 40°) of gas-solid flow. The cleanliness of the bent part and the threaded section of the U-bolt reaches Sa 2.5 level (GB / T 8923.1), and the removal rate of oil stains, rust layers and particulate matters is ≥99%.

[0019] Zero damage guarantee: The hardness of the nano-ceramic particles (HV≤600) is lower than that of the bolt substrate (HV≥800). With precise angle injection, the loss of thread accuracy is <0.01 mm, meeting the requirements of high-precision assembly.

[0020] 2. Environmental protection and cost advantages Reduction of chemical pollution: Composite bio-enzymes (pH 8 - 9) replace strong acids and alkalis, and the COD value of wastewater is reduced by 60% (compared with traditional pickling); the citric acid-phytic acid mixed solution (pH 3 - 4) is biodegradable, and the treatment cost is reduced by 40%.

[0021] Resource recycling: The directional collection rate of rust particles in the eddy current pulse tank is ≥95%, the recycling times of nano-ceramic particles are ≥50 times, and the comprehensive material consumption is reduced by 30%.

[0022] 3. Process efficiency optimization Synchronous treatment of multiple pollutants: The three stages of enzymolysis, rust removal and scouring are integrated. The single-piece cleaning time is ≤12 minutes (the traditional process requires ≥20 minutes), and the energy consumption is reduced by 25%.

[0023] Integration of drying and rust prevention: Vacuum drying (≤10 Pa) is completed synchronously with the spraying of the graphene rust-proof film, the adhesion of the rust-proof film ≥5B (ASTM D3359), and the process flow is shortened by 50%.

[0024] 4. Precise angle control of the fixture: The indexing plate (indexing ±15°) cooperates with the arc-shaped groove, and the repeated positioning accuracy of the inclination angle is ±0.03°, ensuring zero residue of the cleaning liquid. Description of the drawings

[0025] Figure 1 It is a side structure diagram of the fixture of the present invention.

[0026] Figure 2 It is a top sectional view of the chuck of the present invention. Detailed implementation manners

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] The present invention provides a cleaning method for U-shaped bolts, and the specific steps are as follows: Step 1: Biological enzymatic degreasing stage Process parameters: Cleaning liquid: Composite biological enzyme (lipase + protease), pH 8 - 9, temperature 40 - 50°C; Spraying pressure: 0.5 - 1 MPa, lasting for 3 - 5 minutes; Corrosion inhibitor: Add 0.1 - 0.5% mass fraction of organic amine corrosion inhibitor.

[0029] Step 2: Eddy current pulse rust removal stage Process parameters: Acidic solution: A mixed solution of citric acid and phytic acid (volume ratio 3:1), pH 3 - 4; Pulse current: Frequency 25 - 35 kHz, current density 10 - 20 A / dm²; Rotating magnetic field: Intensity 0.2 - 0.5 T, driving the directional migration of rust layer particles.

[0030] Step 3: Gas-solid two-phase flow scouring stage Process parameters: Mixed flow: High-pressure air (2 - 3 MPa) and nano-ceramic particles (diameter 50 - 100 μm, alumina:silicon carbide = 3:1); Jetting angle: Inclined impact on the thread and the bent part at 20 - 40°, and the particle hardness is lower than that of the bolt substrate (HV ≤ 600).

[0031] Step Four: Post-treatment Ultrasonic rinsing: Deionized water at 28 - 35 kHz to remove residual reagents; Vacuum drying: Vacuum degree ≤ 10 Pa, temperature 60°C; Rust prevention treatment: Spraying graphene-based waterborne rust prevention film, thickness ≤ 5 μm.

[0032] 2. As From Figure 1 to Figure 2 The present invention provides an adjustable fixture, Core structure: Substrate 210: Slides along the arc-shaped groove 212 to adjust the initial clamping distance (range 50 - 300 mm); Jaw cylinder 202: The output end is connected to the clamping arm 204, the opening and closing stroke is 20 mm, and the clamping force is 100 - 300 N; Indexing plate 213: Uniformly distributed with 7 indexing holes 23 (-15° to +15°, one gear every 5°), and the angle is locked by a spring taper pin; Detachable chuck 206: The V-groove 1 is adapted to M10 - M30 bolts.

[0033] The fixture fixes the U-bolt at a 5° inclination: The sliding of the substrate 210 drives the clamping arm 204 to rotate around the center of the indexing plate, and the opening of the U-bolt faces downward to avoid the residue of the cleaning liquid.

[0034] Example 1: Cleaning M20×200mm U-bolt Fixture adjustment: Slide the substrate to the initial distance of 220 mm, insert the 5° indexing pin 22 to lock; Install the M20 adapter chuck 206 and set the clamping force to 200 N.

[0035] Cleaning process: Enzymatic degreasing: Cleaning liquid at 45°C, pressure 0.8 MPa, time 4 minutes; Rust removal: Solution with pH 3.5, pulse frequency 30 kHz, magnetic field strength 0.3 T; Flushing: Pressure 2.5 MPa, particle size 80 μm, jetting angle 30°.

[0036] Effect verification: Cleanliness: Sa 2.5 level (GB / T 8923.1); Thread accuracy loss: < 0.01 mm; Adhesion of rust prevention film: ≥ 5B (ASTM D3359).

[0037] The following points should be noted: First, in the description of this application, it should be noted that unless otherwise specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. It can be a mechanical connection or an electrical connection, or it can be the communication inside two components. It can be directly connected. The terms "upper", "lower", "left", "right", etc. are only used to represent the relative position relationship. When the absolute position of the object being described changes, the relative position relationship may change; Second, in the drawings of the disclosed embodiments of the present invention, only the structures related to the disclosed embodiments are involved. For other structures, reference can be made to the general design. Without conflict, the same embodiment and different embodiments of the present invention can be combined with each other; Finally, the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A cleaning method for a U-bolt, characterized in that, Specifically, it includes the following steps: S1. Bioenzymatic oil removal stage: Spraying a composite bioenzyme cleaning solution at 40 - 50 °C on the surface of the U-bolt to decompose grease and organic matter; S2. Eddy current pulse rust removal stage: Immersing the bolt in an eddy current tank containing an acidic solution, and simultaneously applying a high-frequency pulse current of 20 - 40 kHz and a rotating magnetic field to peel off the rust layer and directionally collect rust particles; S3. Gas-solid two-phase flow scouring stage: Impacting the bolt surface with a mixed flow of high-pressure air and nano-ceramic particles to remove residual particulate matter.

2. The cleaning method of a U-bolt according to claim 1, characterized in that, In the step S1, the composite bioenzyme cleaning solution contains lipase and protease, with a pH value of 8 - 9, a spraying pressure of 0.5 - 1 MPa, a duration of 3 - 5 minutes, and a metal corrosion inhibitor with a mass fraction of 0.1 - 0.5% is added to the cleaning solution.

3. The cleaning method of a U-bolt according to claim 1, characterized in that, In the step S2, the acidic solution is a mixed solution of citric acid and phytic acid, with a pH value of 3 - 4, the rotating magnetic field intensity is 0.2 - 0.5 T, and the pulse current frequency is 25 - 35 kHz.

4. A cleaning method for a U-bolt according to claim 1, characterized in that, In the step S3, the high-pressure air pressure is 2 - 3 MPa, the nano-ceramic particle diameter is 50 - 100 μm, the hardness is lower than the bolt substrate, and the spraying direction is inclined at an angle of 20 - 40° with the bolt axis.

5. The cleaning method of a U-bolt according to claim 1, wherein, Before the step S1, a pretreatment operation is also included: Fixing the U-bolt with a fixture with an adjustable fixed angle, making its U-shaped opening inclined downward, the clamping force of the fixture is 100 - 300 N, and it is adapted to different bolt specifications.

6. The cleaning method of a U-bolt according to claim 1, characterized in that, After the step S3, a post-treatment operation is also included: Rinsing with ultrasonic vibration deionized water with a frequency of 28 - 35 kHz, then drying under a vacuum degree ≤ 10 Pa, and spraying a graphene-based waterborne anti-rust film with a thickness ≤ 5 μm.

7. The cleaning method of a U-bolt according to claim 5, characterized in that, The inclination angle of the U-shaped opening is 5°.

8. The cleaning method of a U-bolt according to claim 5, characterized in that: The fixture includes a base (2) and a jaw cylinder (202). The bottom of the base (2) is respectively provided with an arc groove (21) and a dividing plate (213). The dividing plate (213) is coaxially arranged at the center of the arc groove (21). A substrate (210) is provided on the jaw cylinder (202). The substrate (210) is slidably arranged inside the arc groove (21). The substrate (210) is fixed to the dividing plate (213) through a positioning pin (22); The output end of the jaw cylinder (202) is provided with a jaw arm (204). A detachable chuck (206) is provided on the jaw arm (204). The chuck (206) is provided with a V-shaped groove (1) matching the outer diameter of the U-bolt.

9. A cleaning method for a U-bolt according to claim 8, characterized in that, The dividing plate (213) is evenly provided with 7 indexing holes (23), corresponding angles are -15°, -10°, -5°, 0°, +5°, +10°, +15°. The diameter of the indexing hole (23) is φ8H7. The positioning pin (22) is a spring-loaded tapered pin with a taper of 1:50 and surface nitriding treatment.

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