A replaceable multi-layer composite structure elastic sponge sand ring and a preparation method thereof

Abstract

The application discloses a replaceable multi-layer composite structure elastic sponge sand ring and a preparation method thereof. The sponge sand ring comprises, from outside to inside, an abrasive elastic skin, a sponge composite layer and a TPU elastic inner core. The abrasive elastic skin comprises an elastic skin base material and an alumina abrasive layer. The alumina abrasive layer is fixed to the outer surface of the elastic skin base material and forms a grinding working surface. The sponge composite layer is combined with the inner side of the abrasive elastic skin through lamination. The outer peripheral surface of the TPU elastic inner core is hot-melt connected with the inner side of the sponge composite layer and forms a hot-melt combined transition layer. The center of the TPU elastic inner core is provided with a shaft hole for sleeving on a knurled shaft rod. The application realizes the organic unity of high grinding efficiency, excellent nail surface adhesion, reliable interlayer combination and low use cost through the split replaceable design and the four-layer functional gradient composite structure, and is particularly suitable for precise machining scenes such as nail surface shaping, nail edge polishing, nail surface polishing and nail removing in the nail industry.

Description

Technical Field

[0001] This invention belongs to the technical field of nail polishing tools, specifically relating to a replaceable multi-layer composite elastic sponge sander ring and its preparation method. Background Technology

[0002] The nail industry demands increasingly higher precision in processes such as nail shaping, edge polishing, nail buffing, and nail removal. However, traditional nail buffing tools still have the following shortcomings in practical use: 1. Insufficient bonding strength of abrasive layer: Most existing nail polishing heads adopt an integral grinding wheel or sandpaper ring structure, which directly coats or adheres the abrasive to the substrate surface. Under high-speed rotation (10,000 to 20,000 rpm), the bonding strength between the abrasive layer and the substrate is limited. After long-term use, the abrasive is prone to falling off, affecting the polishing effect and user experience. 2. High cost of integrated design: Most small-diameter grinding heads (13mm grade) on the market adopt an integrated design of abrasive layer and shaft core, that is, the shaft core and abrasive part are permanently fixed together. When the abrasive layer wears out, the shaft core and the consumable part are discarded together, resulting in high usage cost and waste of resources. 3. Poor fit of rigid structure: Nail filing needs to fit the tiny curved surface of the nail (small radius of curvature). Traditional rigid filing heads or sandpaper rings are difficult to adapt to changes in the curved surface, which can easily lead to uneven filing or even damage to the nail surface due to excessive local pressure. 4. Cumbersome replacement operation: Existing replaceable grinding heads often use threaded connections or adhesive fixation, requiring auxiliary tools for installation and replacement, which is time-consuming and not conducive to nail technicians quickly changing heads in batch operations.

[0003] Therefore, there is an urgent need to design a replaceable multi-layer composite elastic sponge sand ring to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a replaceable multi-layer composite elastic sponge sander with a diameter of approximately 13mm and a height of approximately 13mm. It features a heat-fusion connection design between the abrasive elastic skin-sponge composite layer and the TPU inner core, and is equipped with a standard 2.35mm knurled roller to enable quick replacement. While ensuring high grinding efficiency and excellent elasticity to the nail surface, it significantly reduces the usage cost for nail technicians.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a replaceable multi-layer composite elastic sponge sanding ring, which is a consumable unit, comprising, from the outside to the inside: Abrasive elastic skin, comprising an elastic skin substrate and an alumina abrasive layer, wherein the alumina abrasive layer is bonded to the outer surface of the elastic skin substrate by a resin binder and forms a grinding working surface; A sponge composite layer, wherein the sponge composite layer and the inner side of the abrasive elastic skin are bonded together by a lamination process; The TPU elastic inner core has an outer peripheral surface that is connected to the inner side of the sponge composite layer by a hot-melt method, and a hot-melt bonding transition layer is formed at the junction of the two. The center of the TPU elastic inner core is provided with a shaft hole for fitting onto a knurled shaft. Among them, the knurled shaft bar is an independent standard part that can be reused more than 500 times and is not a consumable unit. The knurled shaft bar adopts a 2.35mm standard diameter metal shaft bar (such as 304 stainless steel), and its outer surface is provided with a knurled structure with a depth of 0.2-0.5mm and a tooth pitch of 0.5-1.0mm. The knurled structure is straight knurling or mesh knurling.

[0006] Furthermore, the outer diameter of the sponge sand ring is 13±0.5mm, the height is 13±0.5mm, the inner diameter of the shaft hole is 2.35mm, and the inner diameter tolerance of the shaft hole is ±0.02mm, to ensure a tight fit with the knurled shaft and quick assembly / disassembly.

[0007] Furthermore, the alumina abrasive layer has an abrasive particle size of 120# to 600#, the elastic leather substrate is selected from one of non-woven fabric, polyester film or rubber sheet, and has a thickness of 0.2 to 0.8 mm. The alumina abrasive is preferably imported from South Korea to ensure grinding sharpness and durability.

[0008] Furthermore, the sponge composite layer is made of polyurethane sponge, melamine sponge, or polyethylene sponge, with a thickness of 2-5 mm and a porosity of 50%-85%, to provide excellent elastic cushioning and adaptive adhesion to the nail surface.

[0009] Furthermore, the TPU elastic core has a Shore A hardness of 60-90, exhibits a non-foamed or micro-foamed structure, and has a smooth inner wall of the axial hole.

[0010] Furthermore, the abrasive elastic skin and the sponge composite layer are laminated together by adhesive or hot pressing, with a lamination pressure of 0.1 to 0.5 MPa and a lamination temperature of 60 to 120°C.

[0011] Furthermore, the sponge composite layer and the TPU elastic core are connected by hot-melt bonding, with a hot-melt temperature of 120-170°C, a hot-pressing pressure of 0.2-0.8 MPa, and a hot-pressing time of 30-120 seconds.

[0012] This invention also provides a method for preparing a sponge abrasive ring, comprising the following steps: Step 1: Pre-fabrication of abrasive elastic skin. Alumina abrasive and resin binder are mixed at a mass ratio of (70-85):(15-30) to form an abrasive slurry. Anhydrous ethanol is added to adjust the viscosity to 800-1200 mPa·s. The abrasive slurry is coated onto the outer surface of the elastic skin substrate by spraying or scraping. The coating thickness is 0.3-0.6 mm. Then, the elastic skin substrate coated with abrasive slurry is placed in an oven and dried and cured at a temperature of 80-130℃ for 30-60 minutes to make an abrasive elastic skin roll with an abrasive layer on one side. Step 2: Abrasive elastic skin and sponge composite. Align the uncoated abrasive side of the abrasive elastic skin obtained in Step 1 with the sponge sheet, and laminate them together by adhesive or hot pressing. The composite pressure is 0.1-0.5 MPa, the composite temperature is 60-120℃, and the composite time is 30-90 seconds to form an abrasive elastic skin-sponge composite sheet. Step 3: Cut the composite sheet. Cut the composite sheet obtained in Step 2 into strips with a set width (e.g., 13mm) and a set length (matching the outer circumference of the sanding ring). The cutting tolerance is ≤0.2mm. Step 4: Pre-fabrication of TPU elastic inner core. The thermoplastic polyurethane elastomer (TPU) raw material is heated to 180-200℃ in an injection molding machine and melted before being injected into a tubular inner mold. A mandrel is provided in the center of the mold to form a through hole in the center of the TPU elastic inner core. The inner diameter of the hole is 2.35±0.02mm. After cooling, the core is demolded. The hardness of the TPU elastic inner core is controlled at Shore A60-90. Step 5: Hot melt bonding. Wrap the abrasive elastic skin-sponge composite sheet cut in Step 3 around the outer periphery of the TPU elastic core, with the sponge side facing the surface of the TPU elastic core. Place the wrapped component in a special hot press mold and hot press for 30-120 seconds at a temperature of 120-170℃ and a pressure of 0.2-0.8MPa. This melts and softens the surface of the TPU elastic core and allows it to penetrate and fuse with the sponge, forming a hot melt bonding transition layer between the sponge and TPU. After cooling, the sponge composite layer and the TPU elastic core are firmly connected as one, with a bonding strength significantly higher than that of traditional adhesive bonding. Step Six: Cutting, Shaping, and Post-processing. The long strip of abrasive ring material obtained in Step Five is cut axially into individual abrasive ring units with a thickness of 13±0.5mm. Then, the outer circle is precision shaped to ensure that the outer diameter tolerance is ≤0.1mm and the roundness tolerance is ≤0.05mm. The central shaft hole is finely finished to ensure that the tolerance of the inner diameter of 2.35mm is controlled within ±0.02mm. Each finished abrasive ring is dynamically balanced to ensure that the residual imbalance is ≤0.01g·mm. Finally, excess burrs are removed, and the appearance is inspected before packaging as finished products.

[0013] This invention also provides a method for using a sponge sanding ring: In use, insert the reusable 2.35mm standard knurled roller into the central shaft hole of the sponge sanding ring. The knurled structure forms an interference fit to prevent rotation. The grinding surface is the alumina abrasive layer on the elastic abrasive skin. Driven by the nail polishing pen, the nail surface is shaped, polished, or removed at a speed of 10,000 to 20,000 rpm. The sponge composite layer undergoes adaptive compression deformation under the polishing pressure, making the abrasive layer closely conform to the curved contour of the nail surface, achieving uniform surface contact grinding. When the abrasive layer is worn, the operator can directly pull the old sanding ring from the knurled roller by hand, and then insert a new sponge sanding ring to continue working. A single change of shape takes only about 5 seconds.

[0014] The technical effects and advantages of this invention are as follows: 1. Reusable rollers reduce overall costs by over 70%: Knurled rollers, as independent standard accessories, are made of 304 stainless steel. The surface knurling is heat-treated to achieve a hardness of HRC≥40, which is excellent wear resistance. A single roller can be reused more than 500 times without significant wear. Nail technicians only need to replace the sponge sanding ring periodically during use. Compared with the traditional integrated sanding head model where the entire head is discarded each time, the overall cost of use is reduced by more than 70%, significantly reducing the consumable burden on practitioners. 2. The four-layer composite structure achieves functional gradient optimization: The sponge sanding ring consists of the following layers from the outside to the inside: abrasive elastic skin (high-hardness grinding working surface) → sponge composite layer (elastic buffer and curved surface self-adaptation) → TPU elastic inner core (structural support and shaft hole positioning) → knurled shaft (quick loading and unloading and torque transmission). Each layer has a clear function and reasonable division of labor, ensuring that grinding efficiency, curved surface fit and connection reliability are all taken into account. 3. The prefabrication process of abrasive elastic skin ensures uniform distribution of abrasive: The present invention first prefabricates the abrasive on the elastic skin substrate to form an abrasive elastic skin, and then combines it with the sponge. This prefabrication process ensures that the abrasive is evenly distributed and firmly bonded on the surface of the substrate, avoiding the problems of abrasive waste, uneven distribution and insufficient bonding strength caused by the slurry seeping into the pores of the sponge when the abrasive slurry is directly coated on the surface of the sponge in the traditional process. 4. Achieving ultra-high interlayer bonding strength through sponge-TPU hot melt bonding technology: This invention utilizes the surface melting characteristics of TPU at temperatures of 120-170℃, allowing molten TPU to penetrate into the gaps between sponge fibers. After cooling, a dual bonding mechanism of mechanical interlocking and fusion bonding is formed. Peel strength tests have verified that the peel strength of the hot melt bonding surface is ≥3.5N / mm, which is more than 4 times higher than that of traditional adhesive bonding (approximately 0.8N / mm). 5. Standard knurled shaft hole fit, quick and reliable installation: The 2.35mm standard shaft hole of the TPU inner core is connected to the knurled shaft bar through an interference fit. The knurled structure provides reliable anti-rotation torque. No auxiliary tools are required for replacement. It can be completed by manual insertion and removal. A single changeover takes only about 5 seconds. In large-volume nail work, this quick changeover advantage can significantly reduce downtime and improve work efficiency. 6. Imported alumina abrasive ensures high-quality processing results: This invention uses imported alumina abrasive (Al2O3 content ≥99%), which has a complete crystal structure, high hardness, and sharp cutting edge angle. Comparative tests show that its grinding efficiency is 20% to 30% higher than that of ordinary domestic alumina. The surface roughness of the nail surface after processing can reach Ra 0.12 micrometers, which meets the high standard requirements of the nail industry for mirror-level polishing effect. 7. The small size is specially designed for nail art scenarios: The compact size of 13mm diameter and 13mm height perfectly fits the limited working area and slight curvature of the nail surface. Whether it is nail shaping, edge polishing, nail buffing or nail removal, it can be operated flexibly, providing users with a fine, safe and comfortable buffing experience. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the sponge sand ring of the present invention; Figure 2 This is an axial sectional view of the sponge sand ring of the present invention; Figure 3 This is a schematic diagram of the assembly of the sponge sand ring and the knurled shaft of the present invention; Figure 4 This is a flowchart illustrating the manufacturing process of the sponge sand ring of the present invention.

[0016] In the diagram: 100, abrasive elastic skin; 200, sponge composite layer; 300, TPU elastic inner core; 301, shaft hole; 400, heat-fused transition layer; 500, knurled shaft. Detailed Implementation

[0017] 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.

[0018] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] Example 1 Materials preparation:

[0021] Preparation process: (1) Pre-fabrication of abrasive elastic skin: Weigh 320# imported alumina abrasive and phenolic resin at a mass ratio of 80:20 and mix them. Add an appropriate amount of anhydrous ethanol as a diluent and stir thoroughly. Adjust the viscosity of the slurry to 800-1200 mPa·s to obtain the abrasive slurry. Apply the abrasive slurry evenly to one side of the polyester nonwoven fabric by scraping. Control the coating thickness to 0.4 mm. Place the coated nonwoven fabric in an oven and dry and cure it at 100℃ for 40 minutes to make the abrasive elastic skin roll.

[0022] (2) Abrasive elastic skin and sponge composite: The uncoated abrasive side (i.e. the non-woven fabric substrate side) of the abrasive elastic skin is aligned and stacked with the polyurethane sponge sheet. The hot-pressing composite process is used to hot-press the composite at 0.3MPa pressure and 80℃ temperature for 60 seconds, so that the non-woven fabric fibers and sponge fibers form a fusion bond at the interface, and the abrasive elastic skin-sponge composite sheet is obtained.

[0023] (3) Composite sheet cutting: Cut the composite sheet into long strips with a width of 13mm and a length that precisely matches the outer perimeter of the sand ring, and control the cutting tolerance to ≤0.1mm.

[0024] (4) TPU elastic inner core prefabrication: TPU granules are heated to 190°C in an injection molding machine and melted, then injected into a tubular inner core mold. A mandrel is placed in the center of the mold to form a through shaft hole with an inner diameter of 2.35 mm. After cooling and solidification, the core is demolded. The Shore hardness of the obtained TPU inner core is A 82 and the outer diameter is 7 mm.

[0025] (5) Hot melt composite (core process): The cut abrasive elastic skin-sponge composite sheet is tightly wrapped around the outer periphery of the TPU elastic core, ensuring that the sponge side is in contact with the TPU surface and the seams are aligned without overlap. The wrapped component is placed in a hot press mold and hot-pressed for 60 seconds at a temperature of 150℃ and a pressure of 0.5MPa. During this process, the TPU surface melts and softens and penetrates into the gaps between the sponge fibers. After cooling, a strong hot melt bond transition layer is formed at the sponge-TPU interface.

[0026] (6) Cutting, shaping and post-processing: Cut into single sand ring units with a thickness of 13mm along the axial direction, perform precision shaping on the outer circle to an outer diameter of 13mm and a roundness tolerance of ≤0.05mm, finely repair the central shaft hole to ensure an inner diameter of 2.35mm and a tolerance of ±0.02mm, perform dynamic balancing test, and the residual imbalance is ≤0.01g·mm. Finally, remove burrs, perform appearance inspection and packaging.

[0027] Performance test results:

[0028] Comparative experiment: A commercially available nail polishing head of the same specification (abrasive directly coated on the sponge surface + integrated shaft design) was used as a control group. It was compared with the product prepared in Example 1 of this invention under the exact same test conditions (30,000 rpm, polishing pressure 0.5 N, same operator). The results are as follows:

[0029] Experimental conclusions: The above comparative data fully demonstrate that the present invention is significantly superior to existing commercially available products in terms of interlayer bonding strength, nail surface curvature adhesion performance, grinding efficiency, and processing accuracy. At the same time, the split design with reusable shafts greatly reduces the long-term consumable costs for nail technicians, and has significant economic benefits and practical value.

[0030] Example 2 This embodiment shares the same basic preparation process and material system as Example 1. The main difference lies in the targeted adjustments made to some parameters for the rough grinding process, as detailed below:

[0031] Example 3 This embodiment shares the same basic preparation process and material system as Example 1. The main difference lies in the targeted adjustments made to some parameters for the fine polishing process, as detailed below:

[0032] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A replaceable multi-layer composite elastic sponge sanding ring, as a consumable unit, characterized in that, From the outside in, the following are included: Abrasive elastic skin (100) includes an elastic skin substrate and an alumina abrasive layer. The alumina abrasive layer is bonded to the outer surface of the elastic skin substrate by a resin binder and forms a grinding working surface. The sponge composite layer (200) is bonded to the inner side of the abrasive elastic skin (100) by lamination. TPU elastic inner core (300), the outer peripheral surface of the TPU elastic inner core (300) is connected to the inner side of the sponge composite layer (200) by heat fusion, and a heat fusion bonding transition layer (400) is formed at the junction of the two. The center of the TPU elastic inner core (300) is provided with a shaft hole (301) for fitting onto the knurled shaft (500).

2. The replaceable multi-layer composite elastic sponge sanding ring according to claim 1, characterized in that: The outer diameter of the sponge sand ring is 13±0.5mm, the height is 13±0.5mm, the inner diameter of the shaft hole (301) is 2.35mm, and the inner diameter tolerance of the shaft hole is ±0.02mm.

3. The replaceable multi-layer composite elastic sponge sanding ring according to claim 1, characterized in that: The abrasive particle size of the alumina abrasive layer is 120# to 600#, and the elastic leather substrate is selected from non-woven fabric, polyester film or rubber sheet, with a thickness of 0.2 to 0.8 mm.

4. The replaceable multi-layer composite elastic sponge sanding ring according to claim 1, characterized in that: The sponge composite layer (200) is a polyurethane sponge, melamine sponge or polyethylene sponge, with a thickness of 2 to 5 mm and a porosity of 50% to 85%.

5. The replaceable multi-layer composite elastic sponge sanding ring according to claim 1, characterized in that: The TPU elastic core (300) has a hardness of Shore A 60-90.

6. A method for preparing a replaceable multi-layer composite elastic sponge ring as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Pre-fabrication of abrasive elastic skin. Alumina abrasive is mixed with resin binder to form an abrasive slurry, which is then coated onto the outer surface of the elastic skin substrate and dried and cured to form the abrasive elastic skin. Step 2: Abrasive elastic skin and sponge composite: The uncoated abrasive side of the abrasive elastic skin obtained in Step 1 is laminated with the sponge sheet to form an abrasive elastic skin-sponge composite sheet. Step 3: Cutting the composite sheet. Cut the composite sheet obtained in Step 2 into strips of a set width and length. Step 4: TPU elastic inner core prefabrication. The thermoplastic polyurethane elastomer raw material is injection molded into a tubular inner core, and a through axial hole is formed in the center of the tubular inner core. Step 5: Hot melt lamination. Wrap the strip-shaped sheet cut in Step 3 around the outer periphery of the TPU elastic core, with the sponge side facing the surface of the TPU elastic core. Hot press at 120-170℃ and 0.2-0.8MPa for 30-120 seconds to melt the TPU surface and allow it to penetrate and fuse with the sponge. After cooling, a hot melt bonding transition layer is formed. Step Six: Cutting, Shaping and Post-processing. The semi-finished product obtained in Step Five is cut along the axial direction into single sand ring units with a thickness of 13±0.5mm. The outer circle and shaft hole are precisely shaped and dynamically balanced. Burrs are removed and appearance is inspected. The finished product is then packaged.

7. The method for preparing the replaceable multi-layer composite elastic sponge ring according to claim 6, characterized in that: In step one, the mass ratio of alumina abrasive to resin binder is (70-85):(15-30), and the drying and curing temperature is 80-130℃.

8. The method for preparing the replaceable multi-layer composite elastic sponge ring according to claim 6, characterized in that: In step four, the hardness of the TPU elastic core is controlled to Shore A 60-90, and the inner diameter of the shaft hole is 2.35±0.02mm.

9. The method for preparing the replaceable multi-layer composite elastic sponge ring according to claim 6, characterized in that: In step five, the hot-melt connection temperature is 120–170℃, the pressure is 0.2–0.8MPa, and the hot-pressing time is 30–120 seconds.

10. A method of using a replaceable multi-layer composite elastic sponge sanding ring as described in any one of claims 1 to 5, characterized in that: Insert a reusable 2.35mm standard knurled shaft into the central shaft hole of the sponge abrasive ring, and form an interference fit anti-rotation connection through the knurling structure; when the abrasive wears out, pull the old abrasive ring off the knurled shaft and replace it with a new sponge abrasive ring.

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