A sealing structure and processing method for pressure-holding fiberglass products

Abstract

This invention provides a sealing structure and processing method for pressure-holding fiberglass products, including a first mold-closing structure and a second mold-closing structure. Bolt holes are machined at corresponding positions on the first and second mold-closing structures. A thickness-limiting ring is placed at the bolt holes between the mold-closing surfaces. Bolts pass sequentially through the bolt holes of the first and second mold-closing structures and are then locked with nuts. Structural adhesive is filled between the mold-closing surfaces, and the inner side of the mold-closing seam is sealed with sealant. The outer gap of the mold-closing seam is covered and cured with epoxy resin slurry and fiberglass cloth. This invention solves the problems of product morphology changes and reduced sealing reliability caused by traditional polyurethane structural adhesives and bolted connections. It ensures reliable connection of the sealing parts, avoids leakage and damage at the seal, and provides a multi-functional sealing solution with both load-bearing and sealing structures, preventing seal failure due to load-bearing failure or damage to the load-bearing structure due to seal failure.

Description

Technical Field

[0001] This invention belongs to the field of fiberglass products technology, and specifically relates to a sealing structure and processing method for pressure-holding fiberglass products such as packaging boxes, sealed boxes, and airtight boxes that require airtightness. Background Technology

[0002] Fiberglass reinforced plastic (FRP) products represent a new technology in modern materials application and have become an important component of modern industry. FRP significantly improves the quality of polymer materials and can partially replace metal structural components. It plays a crucial role in increasing the strength of polymer materials and reducing product weight. Therefore, the sealing method for pressure-bearing FRP products is particularly important for practicality and stability. In products with complex structures, which often require separate molding or multiple molding processes, the stability of the sealing method for these separate structures is especially critical. Currently, existing technologies have the following drawbacks: First, under high pressure and strong conditions, the sealing edges are susceptible to strong forces, leading to failure. Second, if the sealing method prioritizes maintaining the original shape of the product, polyurethane sealant and bolt reinforcement are required. However, the operation of bolts inevitably carries the risk of air leakage, and polyurethane structural sealant itself has poor sealing properties. All these factors reduce the reliability of the product's sealing requirements. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a sealing structure and processing method for pressure-holding fiberglass products, which solves the problems of product morphology changes and reduced sealing reliability caused by the traditional use of polyurethane structural adhesive and bolt connection structure. It can make the sealing parts reliably connected and will not cause leakage and damage due to the airtightness of the material itself and structural problems.

[0004] The technical solution adopted in this invention is: a sealing structure for pressure-holding fiberglass products, including a first mold-closing structure and a second mold-closing structure. The surfaces of the first mold-closing structure and the second mold-closing structure that meet are called mold-closing surfaces. Bolt holes are machined at corresponding positions of the first mold-closing structure and the second mold-closing structure. A thickness-limiting ring is placed at the bolt holes between the mold-closing surfaces. The thickness-limiting ring is a circular ring structure with an inner diameter greater than or equal to the diameter of the bolt hole. The bolt passes through the bolt holes of the first mold-closing structure in sequence through the bolt holes of the thickness-limiting ring and the second mold-closing structure and is then locked by a nut. Structural adhesive is filled between the mold-closing surfaces. The inner side of the mold-closing gap is sealed with sealant. The outer gap of the mold-closing gap is covered and cured with epoxy resin slurry and fiberglass cloth.

[0005] Preferably, the height of the thickness limiting ring is equal to the design requirement for the gap width of the mold closing surface.

[0006] Preferably, the end faces where the bolts and nuts are located are filled, smoothed, and cured with epoxy resin slurry.

[0007] Preferably, the sealant on the inner side of the mold joint has a semi-circular cross-section, with the straight side facing the inner side of the mold joint and flush with the inner end faces of the first and second mold joint structures, and the other side being an arc side that connects with the structural adhesive.

[0008] Preferably, the structural adhesive is a polyurethane structural adhesive, and the sealant is a silicone-based sealant.

[0009] This invention also provides a method for processing the sealing structure of a pressure-holding fiberglass product, comprising the following steps:

[0010] Step 1: Align and fit the mold faces of the first and second mold-closing structures, and align and machine the bolt holes.

[0011] Step 2: Vertically lift the first mold-closing structure to separate it from the second mold-closing structure, clean the mold-closing surfaces of the first and second mold-closing structures as well as the surface of the thickness limiting ring, and clean it with 75% ethanol and wait for the liquid to completely evaporate;

[0012] Step 3: Apply polyurethane structural adhesive to the entire mold-closing surface of the second mold-closing structure, with a thickness 2mm greater than the design requirement for the mold-closing seam width;

[0013] Step 4: Place the thickness limiting ring at the bolt hole position of the second mold closing structure and align it so that the bolt can pass through the thickness limiting ring;

[0014] Step 5: Move the first mold-closing structure down to align with the mold-closing surface and align the bolt holes, then squeeze out any excess polyurethane structural adhesive.

[0015] Step 6: Insert the bolts from top to bottom and tighten them with nuts. Clean up any excess polyurethane structural adhesive. Before the structural adhesive has fully cured, use an arc-shaped scraper to scrape an arc-shaped groove in the structural adhesive inside the mold joint. Then wait for the polyurethane structural adhesive to fully cure.

[0016] Step 7: Use epoxy resin slurry to completely cover and fill the upper and lower surfaces of the bolts, and wait for it to fully cure.

[0017] Step 8: Seal the arc-shaped groove on the inside of the mold joint with silicone sealant and smooth the inner end face;

[0018] Step 9: Use epoxy resin slurry to hand lay up the fiberglass cloth on the outside of the mold joint and wait for it to fully cure.

[0019] Preferably, the mold closing surface in step 1 satisfies the following requirements: mold closing gap width ≥ 4mm, mold closing surface width ≥ 30mm, and mold closing surface flange width ≥ 20mm.

[0020] Preferably, in step 9, the fiberglass cloth covers the entire outer side of the mold joint, with the upper end of the fiberglass cloth flush with the upper surface after the epoxy resin slurry is filled in step 7, and the lower end of the fiberglass cloth flush with the lower surface after the epoxy resin slurry is filled in step 7.

[0021] The beneficial effects of this invention are:

[0022] 1. This solution addresses the problem of product sealing being compromised due to aging of the adhesive strips caused by traditional structural adhesive sealing, thereby improving the reliability of the sealing interface.

[0023] 2. It has a multi-faceted sealing solution with a load-bearing structure (including: fiberglass product structure, polyurethane structural adhesive, and bolt assembly) and a sealing structure (including: fiberglass product structure, silicone sealant, and polyurethane structural adhesive), which avoids the situation where the seal fails due to stress or the load-bearing structure is damaged due to the seal failure.

[0024] 3. This sealing process can reduce uncertainties in the manufacturing process of complex fiberglass products and enrich the variety and types of products. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the sealing structure of a pressure-holding fiberglass product.

[0026] Reference numerals: 1-First mold closing structure, 2-Structural adhesive, 3-Second mold closing structure, 4-Epoxy resin slurry, 5-Sealant, 6-Bolt assembly, 7-Thickness limiting ring, 8-Fiberglass cloth, A-Flange width of mold closing surface, B-Width of mold closing surface, C-Width of mold closing gap. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Specifically, [the embodiments described herein are...] Figure 1 The perspective is described as follows: the inside refers to the right side of the structure in the figure, the outside refers to the left side of the structure in the figure, and the up and down direction is consistent with the up and down in the figure.

[0028] like Figure 1As shown, a sealing structure for a pressure-holding fiberglass product includes a first mold-closing structure 1 and a second mold-closing structure 3. The first mold-closing structure 1 and the second mold-closing structure 3 are product box structures with airtightness requirements, such as packaging boxes, sealed boxes, and airtight boxes. The surfaces of the first mold-closing structure 1 and the second mold-closing structure 3 that meet are called mold-closing surfaces. Bolt holes are machined at corresponding positions on the first mold-closing structure 1 and the second mold-closing structure 3. The bolt holes extend vertically through the flange positions on the mold-closing surfaces. A thickness-limiting ring 7 is placed at the bolt holes between the mold-closing surfaces of the first mold-closing structure 1 and the second mold-closing structure 3. The thickness-limiting ring 7 is a circular ring structure. The inner diameter of the thickness-limiting ring 7 is greater than or equal to the diameter of the bolt hole. The height of the thickness-limiting ring 7 is equal to the design required mold-closing gap width C. The thickness-limiting ring 7 is integrally molded from resin material and has a certain thickness and hardness, which can limit the mold-closing gap width C when the first mold-closing structure 1 and the second mold-closing structure 3 are sealed, ensuring that the structural adhesive 2 will not overflow completely when the bolt assembly 6 is connected and tightened. Bolts pass sequentially through the bolt holes of the first mold-closing structure 1 and the second mold-closing structure 3, and are then tightened by nuts. The end faces of the bolts and nuts are filled, smoothed, and cured with epoxy resin slurry 4, ensuring that the bolt assembly 6 is completely covered by the epoxy resin slurry 4. The bolt assembly 6 serves to fasten the mold-closing surfaces and form a stable stress relationship, while also stabilizing the uncured structural adhesive 2 and enhancing its adhesion. Structural adhesive 2 is filled between the mold-closing surfaces, and the inner side of the mold-closing seam is sealed with sealant 5. The sealant 5 on the inner side of the mold-closing seam has a semi-circular cross-section, with the straight side facing the inner side of the mold-closing seam and flush with the inner end faces of the first mold-closing structure 1 and the second mold-closing structure 3, and the other side being an arc side that contacts the structural adhesive 2. The outer gap of the mold joint is covered and cured with a paste composed of epoxy resin slurry and fiberglass cloth 8. The epoxy resin slurry 4 has good continuity and can seal the exposed bolts and fiberglass joints, thus avoiding air leakage that may occur due to bolt holes. At the same time, it completely covers the exposed bolt assembly 6, preventing mechanical damage to the bolt assembly 6 from external forces and corrosion from air during product use. After being reinforced with fiberglass cloth, the epoxy resin slurry not only fills and seals the edges of the mold joint, but also provides physical protection for the mold joint, playing a dual role of sealing and mechanical protection, and increasing the overall structural strength.

[0029] In this embodiment, structural adhesive 2 is a polyurethane structural adhesive. Polyurethane structural adhesive has excellent adhesion properties, which can tightly bond the molded surfaces and form a rigid continuous phase sealing structure after curing, providing stress and sealing functions. Simultaneously, this adhesive contains its own curing components, forming a stable curing system that is not affected by air. Sealant 5 is a silicone-based sealant. Silicone-based sealants have good sealing properties and excellent elongation properties. After curing, silicone-based sealants form a continuous and dense structure, suitable for gas sealing requirements under high pressure environments. Furthermore, silicone-based materials have sufficient surface inertness and do not chemically react with various gases, making them suitable for sealing products involving multiple gases. It also exhibits good adhesion to both the cured polyurethane structural adhesive and the fiberglass interface, without undergoing any alteration reaction, resulting in a stable structure.

[0030] This invention also provides a method for processing the sealing structure of a pressure-holding fiberglass product, comprising the following steps:

[0031] Step 1: Align and fit the mold surfaces of the first mold closing structure 1 and the second mold closing structure 3, and align and machine the bolt holes. The mold closing surfaces of the first mold closing structure 1 and the second mold closing structure 3 shall meet the following requirements: mold gap width C≥4mm, mold surface width B≥30mm, and mold surface flange width A≥20mm.

[0032] Step 2: Vertically lift the first mold clamping structure 1 to separate it from the second mold clamping structure 3, clean the mold clamping surfaces of the first mold clamping structure 1 and the second mold clamping structure 3 as well as the surface of the thickness limiting ring 7, and clean it with 75% ethanol and wait for the liquid to completely evaporate.

[0033] Step 3: Apply polyurethane structural adhesive to the mold-closing surface of the second mold-closing structure 3, with a thickness 2mm higher than the design-required mold-closing gap width C.

[0034] Step 4: Place the thickness limiting ring 7 at the bolt hole position of the second mold closing structure 3 and align it so that the bolt can pass through the thickness limiting ring 7;

[0035] Step 5: Move the first mold closing structure 1 down to align with the mold closing surface and align the bolt holes, and squeeze out the excess polyurethane structural adhesive.

[0036] Step 6: Insert the bolts from top to bottom and tighten them with nuts. Clean up any excess polyurethane structural adhesive. Before the structural adhesive 2 is completely cured, use an arc-shaped scraper to scrape an arc-shaped groove out of the structural adhesive 2 inside the mold joint. Then wait for the polyurethane structural adhesive to fully cure.

[0037] Step 7: Use epoxy resin slurry 4 to completely cover and fill the upper and lower surfaces of the bolts, and wait for it to fully cure.

[0038] Step 8: Seal the arc-shaped groove on the inside of the mold joint with silicone sealant 5, and smooth the inner end face;

[0039] Step 9: Use epoxy resin slurry to hand lay up the glass fiber cloth 8 on the outside of the mold joint and wait for it to fully cure. The glass fiber cloth 8 covers the entire outer side of the mold joint. The upper end of the glass fiber cloth is flush with the upper surface of the epoxy resin slurry 4 after filling in step 7, and the lower end of the glass fiber cloth 8 is flush with the lower surface of the epoxy resin slurry 4 after filling in step 7.

[0040] The above describes specific embodiments of the present invention and the technical principles employed. Any modifications or equivalent transformations based on the technical solutions of the present invention should be included within the protection scope of the present invention.

Claims

1. A seal structure for a pressure retaining glass fiber reinforced plastic article, comprising a first mold closure structure and a second mold closure structure, characterized in that: The first mold structure and the second mold structure are connected to each other at a mold surface, and bolt holes are formed in corresponding positions of the first mold structure and the second mold structure; a thickness-limiting ring is arranged between the mold surfaces at the bolt holes, the thickness-limiting ring is a circular ring structure, the inner diameter of the thickness-limiting ring is greater than or equal to the diameter of the bolt hole, the bolt passes through the thickness-limiting ring and the bolt hole of the second mold structure in sequence from the bolt hole of the first mold structure, and then is locked by a nut, structural glue is filled between the mold surfaces, sealing glue is used to seal the inside of the mold joint, and epoxy resin raw paste and glass fiber cloth are used to cover and solidify the gap outside the mold joint, and the end surface where the bolt and the nut are located is filled and smoothed by the epoxy resin raw paste.

2. A seal structure for a pressure retaining glass fiber reinforced plastic article according to claim 1, characterized in that: The height of the thickness-limiting ring is equal to the designed gap width of the mold surface.

3. The seal structure for a pressure retaining glass fiber reinforced plastic product according to claim 1, characterized in that: The cross section of the sealing glue on the inside of the mold joint is semicircular, the straight side is parallel to the inner end surface of the first mold structure and the second mold structure, and the other side is a circular arc side connected to the structural glue.

4. The seal structure for a pressure retaining glass fiber reinforced plastic product according to claim 1, characterized by: The structural glue is polyurethane structural glue, and the sealing glue is silicon-based sealing glue.

5. A method of processing a seal structure of a pressure retaining glass fiber reinforced plastic product, characterized by, The method comprises the following steps: Step 1, aligning the mold surfaces of the first mold structure and the second mold structure, and processing bolt holes in position; Step 2, vertically lifting the first mold structure to separate it from the second mold structure, cleaning the mold surfaces of the first mold structure and the second mold structure and the surface of the thickness-limiting ring, and cleaning with 75% ethanol and waiting for the liquid to completely evaporate; Step 3, coating the mold surface of the second mold structure with polyurethane structural glue, the thickness being 2mm higher than the designed mold joint width; Step 4, placing the thickness-limiting ring at the bolt hole position of the second mold structure and aligning it so that the bolt can pass through the thickness-limiting ring; Step 5, lowering the first mold structure to align the mold surfaces and the bolt holes, and extruding excess polyurethane structural glue; Step 6, inserting the bolt from top to bottom and fastening the bolt with a nut, cleaning the excess polyurethane structural glue, using an arc-shaped scraper to scrape the structural glue inside the mold joint into an arc-shaped groove before the structural glue is completely solidified, and then waiting for the polyurethane structural glue to completely solidify; Step 7, using epoxy resin raw paste to completely cover and fill the upper and lower surfaces of the bolt, and waiting for it to completely solidify; Step 8, sealing the arc-shaped groove inside the mold joint with silicon-based sealing glue, and scraping the inner end surface flat; Step 9, using epoxy resin raw paste to hand lay-up the glass fiber cloth on the outside of the mold joint, and waiting for it to completely solidify.

6. The method of claim 5, wherein the method further comprises: The mold surface in step 1 satisfies the conditions that the mold joint width is greater than or equal to 4mm, the mold surface width is greater than or equal to 30mm, and the mold surface flange width is greater than or equal to 20mm.

7. The method of claim 5, wherein the method further comprises: applying a layer of a sealant to the glass surface of the glass article; and curing the layer of the sealant. In step 9, the glass fiber cloth covers the entire outside of the mold joint, the upper end of the glass fiber cloth is parallel to the upper end surface filled with the epoxy resin raw paste in step 7, and the lower end of the glass fiber cloth is parallel to the lower end surface filled with the epoxy resin raw paste in step 7.

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