Post-burying method of through hole type insert

Abstract

The invention discloses a post-burying method of a through-hole type insert, which comprises the following steps: processing a mounting hole of the through-hole type insert in a composite material structural member, sticking a PET (Polyethylene Terephthalate) film at the mounting hole of a profiling surface of the composite material structural member, and forming an opening consistent with the mounting hole in size at the position corresponding to the mounting hole of the film; the fixing part and the positioning mold are coated with a release agent, the through hole type insert is fixed to the mold through the fixing part, and the composite material structural part is placed on the mold according to the positioning line on the mold; the structural adhesive is mixed, and the structural adhesive is injected into part of the inner hole of the mounting hole for the first time so as to seal a bottom seam between the mounting hole and the positioning mold; the structural adhesive is secondarily blended, and secondary adhesive injection is carried out when the structural adhesive injected for the first time does not form a curing interface so as to fill pores of the whole mounting hole; and demolding after curing at room temperature, and removing the film and redundant structural adhesive on the mold to complete post-burying of the through hole type insert on the composite material structural member.

Description

Technical Field

[0001] The present invention relates to the technical field of composite part inlaying, and particularly relates to a post-embedding method for a through-hole type inlay. Background Art

[0002] In spacecraft composite structural parts, it is often necessary to inlay metal parts for connecting and installing external components and equipment.

[0003] The inlaying methods of metal parts are mainly divided into two types: pre-embedding and post-embedding. The common steps of the post-embedding method for metal inlays are: opening holes in the composite structural parts, installing post-embedded inlays, injecting structural adhesive, curing the components, and demolding to complete the post-embedding. Compared with the pre-embedding method, the post-embedding method has the advantages of easy position accuracy guarantee and low production requirements, so its application is becoming more and more extensive.

[0004] Metal inlays can be divided into blind-hole type and through-hole type according to their structural characteristics. Blind-hole type inlays are easy to position and inlay. However, for through-hole type inlays, during the post-embedding process, the adhesive liquid is likely to flow into the gap between the composite structure and the positioning mold surface, and spread to the surface of the composite structural part and the positioning mold hole under the drive of surface tension. After the adhesive liquid cures, there are problems such as difficult demolding and cleaning.

[0005] The post-embedding method of traditional through-hole type inlays has the following disadvantages:

[0006] 1. During the post-embedding process, generally, an isolation material is bonded to the working surface outside the through-hole of the composite structural part to isolate the adhesive liquid diffused from the through-hole, thereby protecting the working surface. However, this method cannot predict and control the trend and range of adhesive liquid diffusion. Especially for composite structural parts with curved surface characteristics, the adhesive liquid may be affected by gravity in addition to surface tension, resulting in large-area diffusion of the adhesive liquid. And as the adhesive liquid flows out and cures, lack of adhesive is likely to occur in the post-embedded hole, resulting in voids in the post-embedded hole, which seriously affects the post-embedding quality.

[0007] 2. For inlays with position accuracy requirements, the inlays need to be closely attached to the mold and fixed with pins or threaded pins. The thickness of traditional isolation materials will affect the post-embedding installation accuracy of the inlays and the product quality. Summary of the Invention

[0008] Aiming at the deficiencies existing in the prior art, the present invention provides a post-embedding method for a through-hole type inlay. By pasting an ultra-thin PET film at the installation hole of the composite structural part to isolate the adhesive liquid, and at the same time adopting a two-time injection process, the problems of adhesive liquid diffusion pollution, low installation accuracy, and adhesive layer defects in the traditional post-embedding method of through-hole type inlays are solved, and the post-embedding accuracy and quality of through-hole type inlays are effectively improved.

[0009] The present invention provides the following technical solutions:

[0010] A post-embedding method for a through-hole type insert, comprising:

[0011] Treatment of composite structural parts: machining an installation hole for the through-hole type insert on the composite structural part, pasting a PET film at the installation hole on the mold surface of the composite structural part, and providing an opening with the same size as the installation hole at the corresponding position of the installation hole on the PET film;

[0012] Positioning and installation of the insert: coating a release agent on the fixing part and the positioning mold, fixing the through-hole type insert on the positioning mold with the fixing part, and placing the machined composite structural part on the positioning mold according to the positioning line on the positioning mold;

[0013] First injection of glue: preparing a structural adhesive, first injecting the structural adhesive into a part of the inner hole of the installation hole to seal the bottom gap between the installation hole and the positioning mold;

[0014] Second injection of glue: re-preparing the structural adhesive, and performing the second injection of glue when the cured interface has not been formed for the first-injected structural adhesive to fill the pores of the entire installation hole;

[0015] Curing and demolding: demolding after curing at room temperature, and removing the PET film and the excess structural adhesive on the positioning mold to complete the post-embedding of the through-hole type insert on the composite structural part.

[0016] As a further improvement of the present invention, the first injection of glue includes:

[0017] Preparing J133 room-temperature curing structural adhesive, allowing the structural adhesive to stand and cure for a certain time T1 at room temperature. When the viscosity of the structural adhesive rises to 10 - 20 Pa·s, injecting the structural adhesive into the installation hole with a glue gun to a depth of 1 / 5 of the hole depth;

[0018] The structural adhesive injected into the installation hole continues to stand and cure for a certain time T2 at room temperature. When the viscosity of the structural adhesive is greater than or equal to 100 Pa·s, the structural adhesive initially stops flowing and seals the bottom gap between the installation hole and the positioning mold.

[0019] As a further improvement of the present invention, the standing and curing times T1 and T2 are preferably determined according to the curve of the viscosity of the structural adhesive changing with time at room temperature and the results of the curing process test;

[0020] Among them, the curve of the viscosity of the structural adhesive changing with time at room temperature is measured by a rheometer.

[0021] As a further improvement of the present invention, the second injection of glue includes:

[0022] For the secondary dispensing of the room-temperature curable structural adhesive J133, the structural adhesive is left to cure at room temperature for 20 min. Before the first-injected structural adhesive forms a curing interface, use a caulking gun to inject the structural adhesive into the installation hole and fill the pores of the entire installation hole.

[0023] As a further improvement of the present invention, the through-hole type insert includes a smooth-hole type insert and a threaded type insert. The smooth-hole type insert is fixed to the positioning mold by a pin, and the threaded type insert is fixed to the positioning mold by a threaded pin.

[0024] As a further improvement of the present invention, when curing, place a pressing block on the smooth-hole type insert.

[0025] As a further improvement of the present invention, after curing at room temperature for 24 to 48 h, remove the pin, threaded pin, and pressing block, and demold after curing at room temperature for 7 days.

[0026] As a further improvement of the present invention, the thickness of the PET film is 0.01 to 0.03 mm, and the coverage range of the PET film is 2 to 3 cm outside the radius of the installation hole.

[0027] As a further improvement of the present invention, the processing dimension of the installation hole is 1 to 2 mm outside the radius of the envelope dimension of the through-hole type insert.

[0028] As a further improvement of the present invention, the post-embedding method further includes:

[0029] Quality inspection: Use ultrasonic waves or X-rays to detect defects in the post-embedded bonding part.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] The post-embedding method using secondary injection effectively inhibits the outflow and diffusion of the adhesive at the through-hole, effectively reduces the defect of lack of adhesive in the post-embedded hole, and effectively improves the post-embedding quality.

[0032] By using an ultra-thin PET film combined with the first injection to seal the bottom seam, it effectively blocks the diffusion of the adhesive to the surface of the composite structure and the gap of the positioning mold, solves the problem of large-area contamination of the adhesive in the curved surface / gravity environment, and effectively reduces the residual adhesive on the mold surface of the composite structure during demolding.

[0033] At the same time, using an ultra-thin PET film as the isolation material can reduce the influence of the thickness of the isolation material on the post-embedded installation accuracy of the through-hole type insert and improve the post-embedding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flowchart of the post-embedding method provided by the present invention;

[0035] Figure 2Schematic diagram of post-embedding a through-hole type insert using the post-embedding method provided by the present invention;

[0036] Explanation of reference numerals: 1, threaded insert; 2, structural adhesive injected for the second time; 3, pressing block; 4, composite material structural member; 5, PET film; 6, pin; 7, through-hole type insert; 8, structural adhesive injected for the first time; 9, threaded pin; 10, positioning die. Detailed implementation manners

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. 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.

[0038] The present invention will be further described in detail below with reference to the accompanying drawings:

[0039] Please refer to Figure 1 , Figure 2 , this embodiment provides a post-embedding method for a through-hole type insert, including:

[0040] Treatment of composite material structural member: According to the design drawing, a mounting hole for the through-hole type insert is machined on the composite material structural member, and the machining dimension of the mounting hole is 1-2 mm outward from the radius of the envelope dimension of the through-hole type insert; A perforated circular PET film is pasted at the mounting hole on the die face of the composite material structural member, and an opening consistent with the size of the mounting hole is provided at the corresponding position of the mounting hole on the PET film. The thickness of the PET film is 0.01-0.03 mm, and the coverage range of the PET film is 2-3 cm outward from the radius of the mounting hole; Among them, the composite material structural member includes a honeycomb sandwich structural member and a composite material laminated structural member;

[0041] Positioning and installation of insert: The through-hole type insert includes a through-hole type insert and a threaded insert. The through-hole type insert is fixed on the positioning die by a pin, and the threaded insert is fixed on the positioning die by a threaded pin. The positioning die, pin, and threaded pin need to be coated with a release agent before use to facilitate demolding after curing; After the through-hole type insert is fixed, the composite material structural member with holes made is aligned with the positioning die scale line and placed on the positioning die; Among them, the accuracy of the through-hole type insert is guaranteed by the hole position accuracy of the mounting hole on the positioning die;

[0042] First Glue Injection: Prepare the J133 room-temperature curing structural adhesive. Let the structural adhesive stand and cure at room temperature for a certain time T1. When the viscosity of the structural adhesive rises to 10 - 20 Pa·s, the structural adhesive is relatively viscous but still has a certain fluidity. Use a glue gun to inject the structural adhesive into the installation hole to a depth of 1 / 5 of the hole depth. The first-injected structural adhesive continues to stand and cure at room temperature for a certain time T2. When the viscosity of the first-injected structural adhesive is greater than or equal to 100 Pa·s, the first-injected structural adhesive initially stops flowing and can seal the bottom seam between the installation hole and the positioning mold.

[0043] Second Glue Injection: Prepare the J133 room-temperature curing structural adhesive again. Let the structural adhesive stand and cure at room temperature for 20 min. Most of the bubbles formed during stirring when preparing the structural adhesive have floated up and burst after standing. When the first-injected structural adhesive has not formed a curing interface, use a glue gun to inject the structural adhesive into the installation hole and fill the pores of the entire installation hole.

[0044] Among them, the J133 room-temperature curing structural adhesive reaches a certain strength after curing for 24 h - 48 h at room temperature (25 ± 5)°C and is completely cured after 7 days. After complete curing, the room-temperature shear strength is ≥25 MPa.

[0045] Curing and Demolding: Demold after curing at room temperature, and remove the PET film on the positioning mold and the excess structural adhesive to complete the post-embedding of the through-hole insert in the composite material structural part.

[0046] Furthermore, the standing and curing times T1 and T2 for the first glue injection are both optimized according to the curve of the viscosity of the structural adhesive changing with time at room temperature and the results of the curing process tests.

[0047] Among them, the curve of the viscosity of the structural adhesive changing with time at room temperature is measured by a rheometer.

[0048] Furthermore, since the smooth-hole insert is only positioned by pins and cannot fully fit the die surface of the composite material structural part, a pressing block needs to be placed on the smooth-hole insert during curing to rely on the gravity of the pressing block for pressing and curing, while the threaded insert is cured normally.

[0049] The specific curing process is as follows: At room temperature (25 ± 5)°C, after curing for 24 h - 48 h, it reaches a certain strength. Remove the pins, pressing block, and threaded pins. After curing at room temperature for 7 days, the mechanical properties of the structural adhesive reach the best state, and the composite material structural part with the through-hole insert post-embedded is demolded.

[0050] The post-embedding method also includes quality inspection. The quality inspection generally includes internal quality, dimensional accuracy, appearance, and foreign matter inspection. The specific requirements are as follows:

[0051] Internal quality: In accordance with the provisions of GJB1038.1A - 2004 or GJB1038.2A - 2004, use ultrasonic non - destructive testing equipment or X - ray non - destructive testing equipment to detect defects in the post - buried bonding parts, and the quality grade is required to be Grade A.

[0052] Dimensional accuracy: Instruments and equipment such as coordinate measuring machines, theodolites, vernier calipers, measuring machine tools, etc., and inspection fixtures can be used to measure the positioning accuracy of through - hole type inserts in composite structural parts.

[0053] Appearance: There shall be no residual glue on the end face and inner hole of the post - buried insert.

[0054] Foreign matters: The inspection and control of foreign matters shall be carried out in accordance with QJ2850A - 2011.

[0055] Please refer to 1, Figure 2 , the specific steps for post - burying the through - hole type insert and threaded insert using the post - burying method provided by the present invention are as follows:

[0056] S1. Treatment of composite material structural part 4: According to the design drawing, process the installation holes for the through - hole type insert 7 and threaded insert 1 on the composite material structural part 4, paste PET film at the installation holes on the mold surface of the composite material structural part 4, and set openings with the same size as the installation holes at the corresponding positions of the PET film; wherein, the thickness of the PET film is 0.01 - 0.03 mm, and the coverage range of the PET film is 2 - 3 cm outward from the radius of the installation hole.

[0057] S2. Positioning and installation of inserts: The through - hole type insert 7 is fixed on the positioning mold 10 through the pin 6, and the threaded insert 1 is fixed on the positioning mold 10 through the threaded pin 9. The positioning mold 10, pin 6, and threaded pin 9 need to be coated with release agent before use; after the through - hole type insert is fixed, align the processed composite material structural part 4 with the engraved lines of the positioning mold 10 and place it on the positioning mold 10.

[0058] S3. First injection of glue: Prepare the J133 room - temperature - curing structural glue, let the structural glue stand and cure at room temperature for a certain time. When the viscosity of the structural glue rises to 10 - 20 Pa·s, use a glue injection gun to inject the structural glue into the installation hole to a depth of 1 / 5 of the hole depth; the first - injected structural glue 8 continues to stand and cure at room temperature for a certain time. When the viscosity of the first - injected structural glue 8 is greater than or equal to 100 Pa·s, the glue liquid stops flowing initially and can seal the bottom gap between the installation hole and the positioning mold 10.

[0059] S4, secondary glue injection: prepare J133 room temperature curing structural glue for the second time, let the structural glue stand and cure at room temperature for 20 minutes, and when the structural glue 8 injected for the first time does not form a curing interface, use a glue injection gun to inject the structural glue into the mounting hole. The structural glue 2 injected for the second time needs to fill the pores of the entire mounting hole;

[0060] S5, curing: Place a pressing block 3 on the light hole type inlay, and the threaded inlay does not need to be treated. After curing at (25±5)℃ for 24 to 48 hours, remove the pin, pressing block and threaded pin. After curing for 7 days, the mechanical properties of the structural adhesive reach the best state; during curing, the cross section of the composite material structural member 4 is as follows Figure 2 As shown;

[0061] S6, demoulding and cleaning: after the curing is completed, the composite material structure 4 with the through-hole type embedded part is demoulded, and the PET film 5 and the excess structural adhesive on the positioning mold 10 are removed to complete the embedding of the through-hole type embedded part;

[0062] S7. Quality inspection: Inspect the internal quality, dimensional accuracy, appearance and excess materials of the four composite material structures with through-hole type inserts embedded later.

[0063] In summary, the post-embedding method of the through-hole type inlay provided by the present invention has the following advantages:

[0064] The post-embedding method of secondary glue injection is adopted to effectively inhibit the outflow and diffusion of glue in the through-hole, effectively reduce the defects of glue shortage in the post-embedding hole, and effectively improve the post-embedding quality.

[0065] The bottom seam is sealed by ultra-thin PET film combined with the first glue injection, which effectively blocks the diffusion of glue to the surface of composite structural parts and the gap between molds, solves the problem of large-area contamination of glue under curved surface / gravity environment, and effectively reduces the residual glue on the mold surface of composite structural parts during demoulding.

[0066] At the same time, using ultra-thin PET film as the isolation material can reduce the influence of the thickness of the isolation material on the post-embedded installation accuracy of the through-hole type inlay and improve the post-embedded quality.

[0067] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for post-embedding a through-hole type insert, characterized in that, Including: Processing of composite material structural parts: Machining mounting holes for through-hole inserts on the composite material structural parts, pasting PET film at the mounting holes on the profiling surface of the composite material structural parts, and setting openings with the same size as the mounting holes at the corresponding positions of the mounting holes on the PET film; Positioning and installing inserts: Coating release agent on the fixing parts and positioning molds, fixing the through-hole inserts on the positioning molds with the fixing parts, and placing the machined composite material structural parts on the positioning molds according to the positioning lines on the positioning molds; First injection of glue: Preparing structural glue, first injecting the structural glue into a part of the inner hole of the mounting hole to seal the bottom gap between the mounting hole and the positioning mold; Second injection of glue: Preparing structural glue for the second time, and performing the second injection of glue when the first-injected structural glue has not formed a curing interface to fill the pores of the entire mounting hole; Curing and demolding: Demolding after curing at room temperature, and removing the PET film and excess structural glue on the positioning mold to complete the post-embedding of the through-hole inserts on the composite material structural parts.

2. The post-embedding method according to claim 1, characterized in that, The first injection of glue includes: Preparing J133 room-temperature curing structural glue, allowing the structural glue to stand and cure at room temperature for a certain time T1. When the viscosity of the structural glue rises to 10 - 20 Pa·s, injecting the structural glue into the mounting hole with a glue gun to a depth of 1 / 5 of the hole depth; The structural glue injected into the mounting hole continues to stand and cure at room temperature for a certain time T2. When the viscosity of the structural glue is greater than or equal to 100 Pa·s, the structural glue stops flowing preliminarily and seals the bottom gap between the mounting hole and the positioning mold.

3. The post-embedding method according to claim 2, characterized in that, The standing and curing times T1 and T2 are preferably determined according to the curve of the viscosity of the structural glue changing with time at room temperature and the results of the curing process tests; Among them, the curve of the viscosity of the structural glue changing with time at room temperature is measured by a rheometer.

4. The post-embedding method according to claim 2, characterized in that, The second injection of glue includes: Preparing J133 room-temperature curing structural glue for the second time, allowing the structural glue to stand and cure at room temperature for 20 min, and when the first-injected structural glue has not formed a curing interface, injecting the structural glue into the mounting hole with a glue gun and filling the pores of the entire mounting hole.

5. The post-embedding method according to claim 1, wherein The through-hole inserts include smooth-hole inserts and threaded inserts. The smooth-hole inserts are fixed on the positioning molds by pins, and the threaded inserts are fixed on the positioning molds by threaded pins.

6. The post-embedding method according to claim 5, characterized in that When curing, place a pressing block on the smooth-hole inserts.

7. The post-burial method according to claim 6, wherein After curing at room temperature for 24 - 48 h, remove the pins, threaded pins, and pressing blocks, and demold after curing at room temperature for 7 days.

8. The post-embedding method according to claim 1, wherein The thickness of the PET film is 0.01 - 0.03 mm, and the coverage range of the PET film is 2 - 3 cm outward from the radius of the mounting hole.

9. The post-embedding method according to claim 1, wherein The machining size of the mounting hole is 1 - 2 mm outward from the radius of the envelope size of the through-hole insert.

10. The post-embedding method according to claim 1, characterized in that, The post-embedding method further includes: Quality inspection: Detecting defects in the post-embedded bonding part by ultrasonic or X-ray.

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