A gap insulation filling process for a knife-edge hill sensor assembly based on TDR principle

Abstract

The application discloses a gap insulation filling process of a knife-shaped mountain type sensor assembly based on a TDR principle, and belongs to the technical field of sensor assembly gap insulation filling processes.The process comprises the following steps: selecting zirconia material as a filling material insulation isolation module body, selecting an insulating hydrophobic low dielectric constant waterproof AB structure glue as adhesive fixing glue; base treatment, positioning and fixing the zirconia module and the mountain type electrode by using a reticular adhesive tape, glue filling, vibration exhaust, first solidification and adhesive tape removal, overflow glue cleaning and secondary solidification, repair and third solidification, and inspection standby.The application is suitable for the insulation isolation module filling processing of a fresh mixed concrete water content detection knife-shaped mountain type sensor based on the TDR principle, and solves the problems of non-dense gap filling, air bubbles and water absorption of the sensor assembly by optimizing the filling material selection and the process steps, so that the stability of sensor signal transmission and the detection precision are guaranteed, and the service life of the sensor is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of sensor manufacturing technology, specifically relating to a gap insulation filling process for a knife-shaped mountain-shaped sensor assembly based on the TDR principle. Background Technology

[0002] The moisture content of freshly mixed concrete is a core parameter that determines its fluidity, strength, durability, and workability, and directly affects the molding quality and structural safety of the concrete after pouring.

[0003] Currently, most soil parameter rapid testers are used for moisture content testing of fresh-mixed concrete. Their measurement principle is based on radio frequency reflection or electromagnetic induction; data is quickly acquired by inserting a probe into the soil. They are commonly used for soil moisture testing in farmland, orchards, and greenhouses. They feature a portable, tubular design and are battery-powered, requiring no external power source. However, these probe-type soil parameter rapid testers have the following drawbacks: unstable measurement accuracy, susceptible to environmental interference (significantly affected by soil type); poor representativeness of single-point measurements; parameter interference; numerous limitations in experimental scenarios and operations (strict requirements on insertion state); fixed depth, unable to perform stratified monitoring; limited temperature control; simple structure, easily damaged; and the probe is prone to material jamming.

[0004] Chinese invention patent application No. 202610887968.3 proposes a knife-shaped mountain-shaped sensor based on the TDR principle. It employs a knife-shaped mountain-shaped electrode with a wedge-shaped front end for easy insertion into concrete. The overall shape is mountain-like, with a central protrusion serving as the emitter and symmetrical protrusions on both sides serving as grounding electrodes. It is resistant to compression and deformation, ensuring a stable TDR signal circuit. A narrow gap exists between the mountain-shaped emitter and grounding electrodes of this knife-shaped mountain-shaped sensor. The insulating isolation module of this gap must simultaneously meet the characteristics of low dielectric constant, high hardness, insulation, and hydrophobicity (non-absorbent). Furthermore, the gap bonding must be dense and air-free; otherwise, it will lead to disordered sensor signal transmission, poor repeatability of dielectric constant detection, and consequently affect the accuracy of fresh-mixed concrete moisture content detection, and even shorten the sensor's lifespan. Existing insulation filling processes have several drawbacks: First, the selection of filling materials is often unreasonable, with the use of ordinary insulating materials that have high dielectric constants, insufficient hardness, and are prone to water absorption. These materials are unsuitable for testing environments involving freshly mixed concrete that are damp and contain a lot of slurry, leading to decreased insulation performance and increased signal interference. Second, the filling process is rudimentary, using ordinary glue for direct application. This leaves air bubbles in the slits, resulting in poor adhesion. Sand and cement slurry can easily seep into the gaps, damaging the insulation effect. Third, the process steps lack standardization. Incomplete substrate treatment and an unreasonable curing process lead to weak adhesion between the filling module and the electrode, causing problems such as detachment and cracking, further affecting the stability of sensor performance. Fourth, the lack of proper protection during operation allows impurities to contaminate the filling surface, affecting the density and surface smoothness of the filling.

[0005] Therefore, there is an urgent need for an optimized insulation filling process. By rationally selecting filling materials and standardizing process steps, a dense, bubble-free, and hydrophobic insulation filling process can be achieved for the gaps between sensor components. This would address the shortcomings of existing processes, ensure the detection accuracy and service life of the knife-shaped sensor, and meet the stringent requirements for detecting the moisture content of freshly mixed concrete. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a gap insulation filling process for knife-shaped mountain-shaped sensor components based on the TDR principle, so as to achieve dense, bubble-free, and hydrophobic insulation filling of the gaps in the sensor components.

[0007] This invention is implemented as follows: A gap insulation filling process for a knife-shaped, mountain-shaped sensor assembly based on the TDR principle includes the following steps: S1. Filler material selection: The filler material includes the insulating isolation module body and the adhesive for bonding and fixing. The insulating isolation module body is made of zirconium oxide, and the adhesive for bonding and fixing is an insulating, hydrophobic, low dielectric constant, and waterproof AB structural adhesive. S2. Substrate treatment: The gap contact surface of the knife-shaped electrode and the surface of the zirconia module are thoroughly cleaned by ultrasonic cleaning and detergent to remove surface impurities. After cleaning, the contact surface is dehydrated with anhydrous ethanol to ensure that the contact surface is dry and free of residual moisture. S3. Use mesh tape to position and fix the zirconia module to the mountain-shaped electrode, ensuring that the zirconia module fits tightly against the gap contact surface of the mountain-shaped electrode without loosening or shifting. The core purpose is to enhance the subsequent vibration and air venting effect, allowing the air in the slit gap to be smoothly discharged and avoiding air residue due to module loosening. At the same time, use mesh tape to block one side of the slit gap to form a sealing edge, preventing glue leakage during subsequent glue filling. S4. Adhesive filling: Using a glue gun, slowly squeeze the insulating, hydrophobic, low dielectric constant waterproof AB structural adhesive into the narrow gap, so that the waterproof AB structural adhesive can evenly and naturally penetrate into the narrow gap until the adhesive fills the entire gap and the surface is slightly raised to ensure that there are no gaps. S5. Vibration and air removal: Place the sensor assembly filled with glue on the vibration table, turn on the vibration table to perform vibration and air removal. Adjust the vibration frequency and vibration time according to the gap size to ensure that the air in the slit gap is fully removed and the glue completely fills the gap without any air bubbles remaining. After vibration, observe the glue surface. If there are depressions, add glue in time until it is full. S6. First Curing and Tape Removal: Place the sensor assembly after vibration and degassing at room temperature for the first curing, which takes 2-4 hours. When the adhesive reaches a semi-cured state, gently remove the mesh tape on the surface with a blade. Avoid scratching the adhesive surface and electrodes during the removal process to ensure a smooth filling surface. S7. Excess Adhesive Cleaning and Secondary Curing: Gently remove excess adhesive from the surface of the sensor assembly using an adhesive scraper. During the scraping process, keep the tool moving smoothly to ensure that the adhesive surface is smooth, burr-free, and free of bumps. After cleaning, place the sensor assembly in a temperature chamber for secondary curing. Set the temperature to 80-100℃ and the curing time to 4-6 hours to ensure that the adhesive is completely cured and that the zirconia module is firmly bonded to the mountain-shaped electrode. S8. Repair and Tertiary Curing: After the secondary curing is completed, remove the sensor assembly and visually inspect the filling of the slit gap. If any unfilled areas or uneven spots are found in the gap, repair them with waterproof AB structural adhesive. After repair, ensure that the surface is smooth and free of uneven spots. After repair, put the sensor assembly back into the temperature chamber for tertiary curing. Set the temperature to 80-100℃ and the curing time to 2-3 hours to further improve the bonding strength and filling density.

[0008] Furthermore, it also includes: S9. Inspection and Preparation: After the three curing cycles are completed, the sensor assembly is removed and visually inspected to confirm that the slit gap is filled densely, without air bubbles or voids, the adhesive surface is smooth and without bumps, and the zirconium oxide module is firmly bonded to the mountain-shaped electrode without loosening. After passing the inspection, the sensor assembly is properly stored for future use in the subsequent overall assembly of the sensor.

[0009] Furthermore, during the glue filling process in step S4, the glue gun must be moved at a constant speed.

[0010] Furthermore, in steps S3-S4, operators must wear gloves during the operation to prevent glue from getting on their hands and affecting the operation, and to prevent contamination from impurities on their hands.

[0011] Furthermore, the machining precision of the zirconia module must perfectly match the gap between the mountain-shaped electrodes, with an error not exceeding 0.05mm, to ensure a tight fit.

[0012] The advantages of this invention are: 1. The filling material has strong adaptability. Zirconia material is selected as the body of the insulation module. It has the characteristics of low dielectric constant, high hardness, easy processing, insulation, hydrophobicity and non-absorbency. It is suitable for the testing environment of fresh concrete with moisture and a lot of slurry. It can effectively prevent moisture and slurry from seeping into the gaps and ensure insulation performance. When combined with insulating hydrophobic low dielectric constant waterproof AB structural adhesive, the bonding strength is high and the dielectric constant is matched, which further improves the insulation and isolation effect.

[0013] 2. The filling is dense and air-free. Through standardized substrate treatment and vibration degassing steps, air and impurities in the slit gaps are completely removed, ensuring that the waterproof AB structural adhesive completely fills the gaps without air bubbles or voids. This avoids signal interference caused by air, improves the repeatability and stability of the sensor's dielectric constant detection, and thus improves the accuracy of fresh-mixed concrete moisture content detection.

[0014] 3. Strong adhesion and long service life: Through a multi-stage curing process and positioning and fixing steps, the zirconia module is firmly bonded to the mountain-shaped electrode, making it less prone to problems such as falling off and cracking. At the same time, the zirconia material has high hardness and wear resistance, and the waterproof AB structural adhesive is waterproof and resistant to slurry erosion, effectively extending the service life of the sensor and adapting to complex construction site environments.

[0015] 4. The process is standardized and highly operable, clearly defining the operational requirements and key control points for each step. From material selection and substrate treatment to curing inspection, the process is clear and the steps are standardized, allowing operators to follow the standards, reducing operational difficulty, ensuring consistent filling quality during mass production, and improving production efficiency.

[0016] 5. Improve the overall performance of the sensor. The insulating isolation module processed by this technology can effectively isolate the emitter and the ground electrode, prevent short circuits, and avoid sand, gravel, and cement slurry getting stuck between the two electrodes. This ensures a tight fit between the sensor and the fresh concrete. At the same time, in conjunction with the temperature compensation structure, it further improves the detection accuracy and signal transmission stability of the sensor, providing a reliable guarantee for the detection of moisture content in fresh concrete. Attached Figure Description

[0017] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram of the knife-shaped mountain-shaped sensor structure adapted to the process of this invention.

[0019] Figure 2 yes Figure 1 A sectional view.

[0020] Figure label: 1-Electrical electrode, 11-Emitter, 12-Grounding electrode, 2-Zirconium oxide, 3-Waterproof AB glue. Detailed Implementation Example 1

[0021] Figure 1 and Figure 2The diagram shows a schematic of the knife-shaped mountain-shaped sensor structure adapted to the process of this invention. The knife-shaped mountain-shaped sensor adapted to the TDR principle has a knife-shaped wedge-shaped electrode 1 at the front end, and the whole is mountain-shaped. The middle protrusion is the emitter 11, and the two protrusions on both sides are the grounding electrodes 12. The insulating isolation module zirconia 2 filled in this process is located in the narrow gap between the emitter 11 and the grounding electrode 12.

[0022] This embodiment provides a gap insulation filling process for a knife-shaped mountain-shaped sensor assembly based on the TDR principle, adapted to a knife-shaped mountain-shaped sensor for detecting the moisture content of freshly mixed concrete. The specific process steps are as follows: S1. Filling Material Selection: The filling material includes the insulating module body and the adhesive for bonding and fixing. The two work together to ensure that the insulating module has the characteristics of low dielectric constant, high hardness, insulation, and hydrophobicity (non-absorbency) after filling. The specific selection is as follows: 1.1 Insulation and isolation module body: Zirconia material is selected. This material has the advantages of low dielectric constant, high hardness, and easy processing. It also has good insulation and hydrophobicity. It does not absorb water and is not easily corroded by fresh concrete slurry, making it suitable for the humid detection environment of fresh concrete. According to the gap size (width 0.4mm, length 132mm) and shape between the mountain-shaped emitter and grounding electrode of the knife-shaped sensor, the zirconia material is processed into a module that matches the mountain-shaped electrode structure, ensuring that the module can be tightly inserted into the gap between the mountain-shaped emitter and grounding electrode without leaving any excess gap.

[0023] 1.2 Adhesive for bonding and fixing: Select insulating, hydrophobic, low dielectric constant, waterproof AB structural adhesive with a dielectric constant ≤3 and a bonding strength ≥15MPa. This adhesive has good insulation, hydrophobicity, waterproof performance and bonding strength. The dielectric constant is matched with the zirconia material, which can effectively bond the zirconia module and the mountain-shaped electrode into one piece. At the same time, it can fill the narrow gaps, is not easy to generate air bubbles, and has excellent waterproof performance, which can prevent water and cement slurry in fresh concrete from seeping into the gaps, further improving the insulation and isolation effect. S2. Substrate treatment: The gap contact surface of the mountain-shaped electrode (304 stainless steel) and the surface of the zirconia module are cleaned with ultrasonic cleaning and detergent for 15 minutes to remove surface oil and dust. After cleaning, the surface is dehydrated with anhydrous ethanol and dried. After drying, the operator wears dust-free gloves to carry out subsequent operations.

[0024] Positioning and sealing: S3. Mesh tape positioning: Use mesh tape to fix the zirconia module to the mountain-shaped electrode to ensure a tight fit. At the same time, use mesh tape to block the lower end of the slit gap to prevent glue leakage. Wear clean gloves throughout the operation. S4. Adhesive filling: Use a glue gun to squeeze the waterproof AB structural adhesive into the narrow gap at a uniform speed until the adhesive fills the gap and the surface is slightly raised to avoid air bubbles from getting in. S5. Vibration venting: Place the sensor assembly on the vibration table, vibrate at a frequency of 50Hz for 2 minutes to fully expel the air in the gap. If the glue surface is concave, add glue until it is filled. S6. First curing and tape removal: Curing at room temperature (25℃) for 3 hours, after the adhesive has reached a semi-cured state, gently remove the mesh tape with a blade; S7. Excess Adhesive Cleaning and Secondary Curing: Use a scraper to remove excess adhesive from the surface, ensuring a smooth surface without bumps; place the component in a temperature chamber, set the temperature to 90℃, and cure for 5 hours to complete the secondary curing; S8. Repair and Third Curing: Visually inspect and repair any unfilled areas and surface irregularities with adhesive. After repair, place the area in a temperature chamber and cure at 90℃ for 2.5 hours to complete the third curing. S9. Inspection and Reserve: Visual inspection to confirm that the filling is dense, free of air bubbles, and the surface is smooth, and that the zirconia module is firmly bonded to the electrode. After passing the inspection, store for reserve.

[0025] To ensure the quality of the filling process and guarantee sensor performance, the following key control points are set for this process: Material control points: The machining precision of the zirconia module must be perfectly matched with the gap of the mountain-shaped electrode, with an error not exceeding 0.05mm, to ensure a tight fit; the waterproof AB structural adhesive must be tested for performance in advance to confirm that its dielectric constant, insulation, hydrophobicity and bonding strength meet the requirements, and to avoid using unqualified adhesives.

[0026] Operation control points: The contact surface after substrate treatment must be dry and free of impurities. Gloves must be worn throughout the operation to prevent contamination. The glue extrusion process must be at a uniform speed to avoid air bubbles from being mixed in. Vibration and air venting must be sufficient to ensure no air bubbles remain. The glue scraping must be smooth to avoid uneven surfaces affecting the smooth insertion of sensors into the fresh-mixed concrete.

[0027] Curing control points: Strictly control the curing temperature and time at each stage. For room temperature curing, ensure the environment is dry and dust-free. For temperature chamber curing, control the temperature to be uniform to avoid local overheating, which may cause the adhesive to crack, the zirconia module to deform, and affect the bonding effect and insulation performance.

[0028] Inspection control points: Visual inspection is required after each curing step. Any problems found should be repaired in time. The final inspection must ensure that the filling is dense, free of air bubbles, and the surface is smooth. The zirconium oxide module and the electrode must be firmly bonded. Components that do not meet the requirements must be refilled.

[0029] The insulating isolation module processed in this embodiment has been tested and found to have a stable dielectric constant, good insulation performance, and is hydrophobic and non-absorbent. There are no air bubbles or voids in the slit gaps. The zirconia module is firmly bonded to the mountain-shaped electrode. After being assembled into a sensor, the signal transmission is stable, and the accuracy error of detecting the moisture content of freshly mixed concrete is ≤±0.5%, which is suitable for the testing needs of construction sites. Example 2

[0030] The difference between this embodiment and Embodiment 1 is that the insulating module body is made of zirconia ceramic material with a processing accuracy error ≤0.05mm, suitable for knife-shaped mountain-shaped electrodes with a gap width of 0.4mm; the waterproof AB structural adhesive is selected as a high-temperature resistant type with a dielectric constant ≤2.8 and an adhesion strength ≥18MPa, suitable for sensor processing in high-temperature environments; the substrate treatment uses ultrasonic cleaning with a neutral detergent for 20 minutes, followed by drying (temperature 60℃, time 10 minutes) to ensure the contact surface is completely dry; vibration exhaust uses a vibration frequency of 60Hz for 3 minutes; the first curing time is 4 hours at room temperature, the second curing time is 6 hours at 100℃, and the third curing time is 3 hours at 100℃. The remaining process steps are basically the same as in Embodiment 1.

[0031] The insulating isolation module processed in this embodiment has stronger high temperature resistance and wear resistance, and stronger adhesion. It is suitable for use with sensors in harsh construction sites such as the seaside and high temperature sites. The detection accuracy error is ≤±0.3%, which further improves the stability and service life of the sensor.

[0032] This invention is applicable to the filling and processing of the insulation module of the knife-shaped sensor for detecting the moisture content of freshly mixed concrete based on the TDR principle. By optimizing the selection of filling materials and process steps, it solves problems such as non-dense filling of sensor components, air bubbles, and water absorption, ensuring the stability of sensor signal transmission and detection accuracy, and extending the service life of the sensor.

[0033] The above embodiments and figures are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A gap insulation filling process for a knife-shaped, mountain-shaped sensor assembly based on the TDR principle, characterized in that: Includes the following steps: S1. Filler material selection: The filler material includes the insulating isolation module body and the adhesive for bonding and fixing. The insulating isolation module body is made of zirconium oxide, and the adhesive for bonding and fixing is waterproof AB structural adhesive with insulation, hydrophobicity and low dielectric constant. S2. Substrate treatment: The gap contact surface of the knife-shaped electrode and the surface of the zirconia module are thoroughly cleaned by ultrasonic cleaning and detergent to remove surface impurities. After cleaning, the contact surface is dehydrated with anhydrous ethanol to ensure that the contact surface is dry and free of residual moisture. S3. Mesh Tape Positioning: Mesh tape is used to position and fix the zirconia module to the mountain-shaped electrode, ensuring that the zirconia module fits tightly against the gap contact surface of the mountain-shaped electrode without loosening or shifting. The core purpose is to enhance the subsequent vibration and air venting effect, allowing air in the slit gap to be smoothly discharged and avoiding air residue due to module loosening. At the same time, the mesh tape is used to block one side of the slit gap to form a sealing edge, preventing glue leakage during subsequent glue filling. S4. Adhesive filling: Using a glue gun, slowly squeeze the insulating, hydrophobic, low dielectric constant waterproof AB structural adhesive into the narrow gap, so that the waterproof AB structural adhesive can evenly and naturally penetrate into the narrow gap until the adhesive fills the entire gap and the surface is slightly raised to ensure that there are no gaps. S5. Vibration and air removal: Place the sensor assembly filled with glue on the vibration table, turn on the vibration table to perform vibration and air removal. Adjust the vibration frequency and vibration time according to the gap size to ensure that the air in the slit gap is fully removed and the glue completely fills the gap without any air bubbles remaining. After vibration, observe the glue surface. If there are depressions, add glue in time until it is full. S6. First Curing and Tape Removal: Place the sensor assembly after vibration and degassing at room temperature for the first curing, which takes 2-4 hours. When the adhesive reaches a semi-cured state, gently remove the mesh tape on the surface with a blade. Avoid scratching the adhesive surface and electrodes during the removal process to ensure a smooth filling surface. S7. Excess Adhesive Cleaning and Secondary Curing: Gently remove excess adhesive from the surface of the sensor assembly using an adhesive scraper. During the scraping process, keep the tool moving smoothly to ensure that the adhesive surface is smooth, burr-free, and free of bumps. After cleaning, place the sensor assembly in a temperature chamber for secondary curing. Set the temperature to 80-100℃ and the curing time to 4-6 hours to ensure that the adhesive is completely cured and that the zirconia module is firmly bonded to the mountain-shaped electrode. S8. Repair and Tertiary Curing: After the secondary curing is completed, remove the sensor assembly and visually inspect the filling of the slit gap. If any unfilled areas or uneven spots are found in the gap, repair them with waterproof AB structural adhesive. After repair, ensure that the surface is smooth and free of uneven spots. After repair, put the sensor assembly back into the temperature chamber for tertiary curing. Set the temperature to 80-100℃ and the curing time to 2-3 hours to further improve the bonding strength and filling density.

2. The gap insulation filling process for a knife-shaped, mountain-shaped sensor assembly based on the TDR principle as described in claim 1, characterized in that: Also includes: S9. Inspection and Preparation: After the three curing cycles are completed, the sensor assembly is removed and visually inspected to confirm that the slit gap is filled densely, without air bubbles or voids, the adhesive surface is smooth and without bumps, and the zirconium oxide module is firmly bonded to the mountain-shaped electrode without loosening. After passing the inspection, the sensor assembly is properly stored for future use in the subsequent overall assembly of the sensor.

3. The gap insulation filling process for a knife-shaped, mountain-shaped sensor assembly based on the TDR principle as described in claim 1, characterized in that: During the glue filling process in step S4, the glue gun must be moved at a constant speed.

4. The gap insulation filling process for a knife-shaped, mountain-shaped sensor assembly based on the TDR principle as described in claim 1, characterized in that: In steps S3-S4, operators must wear gloves during the operation to prevent glue from getting on their hands and affecting the operation, and to prevent contamination from impurities on their hands.

5. The gap insulation filling process for a knife-shaped, mountain-shaped sensor assembly based on the TDR principle as described in claim 1, characterized in that: The machining precision of the zirconia module must be perfectly matched with the gap between the mountain-shaped electrodes, with an error not exceeding 0.05mm, to ensure a tight fit.

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