Bonding process of a test specimen with a lap joint structure

Abstract

The application provides a bonding process of a sample with a lap joint structure. The bonding process comprises the following steps: (1) providing DW-3 low-temperature glue, and obtaining a gel time of the DW-3 low-temperature glue by a preset method; (2) determining a pre-curing process of the DW-3 low-temperature glue based on the gel time, and respectively performing first pre-curing treatment on a first metal plate coated with the DW-3 low-temperature glue and a second metal plate coated with the DW-3 low-temperature glue according to the pre-curing process, to obtain the first metal plate and the second metal plate after pre-curing; and (3) connecting the first metal plate and the second metal plate after pre-curing to form a sample to be completely cured with a lap joint structure, placing the sample to be completely cured in a hot press tank, and performing second complete curing treatment on the sample according to a curing process to be adopted, to obtain the sample. The bonding process can prevent the adhesive layer from seeping from the edge of the lap joint structure.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal bonding process, and particularly relates to a bonding process for a sample with a lap joint structure. BACKGROUND

[0002] High-pressure gas cylinders applied to space technology can be divided into two categories according to application and structure: metal gas cylinders and composite gas cylinders. Compared with metal gas cylinders, composite gas cylinders have excellent performance such as light weight, low energy consumption, strong pressure-bearing capacity and high reliability, and are ideal pressure vessels for storing various liquids or gases to maintain the normal work of the subsystems of artificial satellites, space shuttles, launch vehicles and space stations. However, due to the harsh service environment of composite gas cylinders, there are still many problems in the wide application of composite gas cylinders, mainly in the following two aspects: for liquid hydrogen cylinders, the ultra-low temperature mechanical properties need to be improved and hydrogen molecule permeation needs to be overcome, and for liquid oxygen cylinders, the material compatibility with liquid oxygen needs to be overcome. Based on the metal coating on the composite material cylinder body, a high-pressure gas cylinder with a metal liner-composite material layer-metal coating layer composite structure is formed, which fully utilizes the respective advantages of metal and composite material to meet the requirements of impact resistance and leakage prevention. Among them, the composite material layer is protected by the double layers of metal lining and metal coating layer, which can effectively avoid problems such as liquid oxygen compatibility and hydrogen permeation.

[0003] Considering that the composite material gas cylinder is an irregular rotating body, the mold needs to be designed according to the profile size of the composite material gas cylinder to form the bottle nozzle metal coating layer, the bottle nozzle closing metal coating layer, the bottle bottom metal coating layer and the cylinder body metal coating layer through multiple passes of stamping and deep drawing processes. When the composite material gas cylinder is coated with metal, in order for the metal coating layer to completely cover the composite material cylinder body, a lap joint process is involved between the cylinder body metal coating layer and the bottle nozzle metal coating layer and the bottle bottom metal coating layer, and the metal-metal bonding process needs to be researched to determine the lap length, the thickness of the adhesive layer and the roughness polishing condition, etc.

[0004] Since the service environment of the composite material gas cylinder is in the ultra-low temperature environment of liquid hydrogen or liquid oxygen, the adhesive selected is DW-3 low-temperature glue with excellent performance under low-temperature conditions. This low-temperature glue is an epoxy resin low-temperature glue, which is characterized by good flowability at room temperature. In the prior art, the DW-3 low-temperature glue is cured by one-time curing forming process, and the low-temperature glue is easy to seep out from the edge of the lap joint structure. The seepage of the adhesive layer at the edge of the lap joint structure will cause some problems. On the one hand, it is difficult to ensure that the adhesive layer thickness in the lap joint area meets the designed adhesive layer thickness, and on the other hand, the adhesive layer seeped out at the edge will accumulate at the lap joint edge after curing, and it is difficult to accurately evaluate the bonding performance of the metal plate through subsequent pull-off process tests. SUMMARY

[0005] The present application aims to provide a bonding process capable of preventing glue layer in the lap joint structure from seeping out of the lap joint edge, having the advantages of uniform glue layer distribution and stable bonding.

[0006] To achieve the above-mentioned purpose, the present application provides a bonding process for a sample with a lap joint structure, which is used to prevent glue layer in the lap joint structure from seeping out of the lap joint edge, the sample comprising a first metal plate, a second metal plate with a first end lap on one end of the first metal plate and bonded to the first metal plate by DW-3 low temperature glue, and the first metal plate and the second metal plate connected to form the lap joint structure, the bonding process comprising:

[0007] (1) providing DW-3 low temperature glue, obtaining the gel time of the DW-3 low temperature glue by a preset method, the gel time being the gel time corresponding to the curing process to be adopted for curing the DW-3 low temperature glue;

[0008] (2) determining the pre-curing process of the DW-3 low temperature glue based on the gel time, and respectively performing first pre-curing treatment on the first metal plate coated with the DW-3 low temperature glue and the second metal plate coated with the DW-3 low temperature glue according to the pre-curing process, to obtain the first metal plate and the second metal plate completed pre-curing;

[0009] (3) connecting the first metal plate and the second metal plate completed pre-curing to form a sample to be completely cured with a lap joint structure, packaging the sample to be completely cured with a vacuum bag and placing it in a hot press tank, and performing second complete curing treatment according to the curing process to be adopted, to obtain the sample.

[0010] In a specific embodiment, the process parameters of the curing process to be adopted include temperature parameters and pressure parameters, and the gel time is the gel time corresponding to the temperature parameters of the curing process to be adopted.

[0011] In a specific embodiment, the temperature parameters include: the first curing temperature is 60℃, the first heating rate is 1.5℃ / min, and the first holding time is 480min; and the obtained gel time corresponding to the temperature parameters is 105min.

[0012] In a specific embodiment, the process parameters of the pre-curing process in step (2) include: the second curing temperature is 60℃, the second heating rate is 1.5℃ / min, and the second holding time is 100-110min.

[0013] In a specific embodiment, the preset method in step (1) includes:

[0014] Provide DW-3 low-temperature adhesive and determine the curing process to be used to cure the DW-3 low-temperature adhesive;

[0015] A measuring device is provided for measuring the gel point of the DW-3 low-temperature adhesive. The measuring device includes a measuring mold with a receiving space, a DW-3 low-temperature adhesive housed in the receiving space, a fiber Bragg grating sensor and a thermocouple completely immersed in the DW-3 low-temperature adhesive, a fiber optic demodulator connected to the fiber Bragg grating sensor, and a data logger connected to the thermocouple. The fiber Bragg grating sensor and the thermocouple are arranged adjacent to each other so that they experience the same temperature.

[0016] The measuring device is placed in an autoclave, and the DW-3 low-temperature adhesive is cured according to the temperature parameters. Wavelength data collected by the fiber optic demodulator and temperature data collected by the data logger during the curing process are obtained.

[0017] Based on the wavelength data and the temperature data, the strain data of the DW-3 low-temperature adhesive is calculated, and the curing time corresponding to the transition point from the viscous flow state to the elastic state in the strain data is taken as the gel time of the DW-3 low-temperature adhesive.

[0018] In one specific embodiment, the measuring mold includes a substrate, a template disposed on the substrate, and a black glue frame disposed on the side of the template away from the substrate. The template is made of polytetrafluoroethylene material, and the black glue frame is a rectangular frame. The template and the black glue frame together form the accommodating space with an opening at the top.

[0019] In one specific implementation, step (2) includes:

[0020] A pre-curing process is determined, wherein the gel time is used as the holding time of the pre-curing process, and the curing temperature and heating rate in the temperature parameters are used as the curing temperature and heating rate of the pre-curing process, respectively.

[0021] The first metal plate and the second metal plate are pretreated respectively. The pretreatment includes sanding and phosphoric acid anodizing of the overlapping areas of the first metal plate and the second metal plate in sequence.

[0022] Apply a pre-set thickness of DW-3 low-temperature adhesive to the overlapping areas of the first metal plate and the second metal plate using a scraper tool. The pre-set thickness is half the target adhesive layer thickness.

[0023] The first metal plate coated with DW-3 low-temperature glue and the second metal plate coated with DW-3 low-temperature glue are placed in a hot pressing tank, and the DW-3 low-temperature glue is cured according to the pre-curing process to obtain a first metal plate and a second metal plate after pre-curing.

[0024] In a specific embodiment, the step (3) comprises:

[0025] A lapping mold is provided, which comprises an aluminum plate, a thin backing plate and a plurality of backing blocks, the thickness of the thin backing plate is the target glue layer thickness, and the thickness of each of the plurality of backing blocks is the thickness of the first metal plate;

[0026] The first metal plate after pre-curing and the thin backing plate are placed on the aluminum plate, and the thin backing plate is arranged close to one end of the first metal plate coated with DW-3 low-temperature glue;

[0027] The plurality of backing blocks are arranged on the thin backing plate in a spaced manner to support the second metal plate;

[0028] The second metal plate is placed on the plurality of backing blocks, and the lapping area of the second metal plate coated with DW-3 low-temperature glue is opposite to the lapping area of the first metal plate coated with DW-3 low-temperature glue for bonding, thereby forming a sample to be completely cured with a lapping structure;

[0029] The first metal plate, the second metal plate and the lapping mold are packaged as a whole with a vacuum bag, vacuum treatment is performed, and then the sample is placed in a hot pressing tank for second complete curing treatment according to the curing process to be adopted, thereby obtaining the sample, wherein the curing process to be adopted comprises: heating at a heating rate of 1.5℃ / min to 60℃, and keeping at 60℃ for 480min, and then cooling with the furnace, and the vacuum bag is pumped to 0.1MPa vacuum during the whole curing process, and the hot pressing tank is pressurized to 0.05MPa.

[0030] In a specific embodiment, the target glue layer thickness is 0.1mm.

[0031] In a specific embodiment, the sample is a glue joint pull-off sample.

[0032] The beneficial effects of the present application at least include:

[0033] The adhesive process of the sample with the lap joint structure provided by the present application adopts a secondary curing molding process, first, the gel point corresponding to the temperature parameter of the curing process of the DW-3 low-temperature glue is obtained, then the process parameters of the pre-curing process are set based on the gel point, the first metal plate and the second metal plate are bonded to form a lap joint structure after the pre-curing process is completed, and finally, the sample is obtained through complete curing treatment. In this way, the DW-3 low-temperature glue used for bonding has good viscosity and gel performance through the first pre-curing treatment, that is, the low-temperature glue can maintain the viscosity state while taking into account the poor flow characteristics, and then through the second complete curing treatment, the first metal plate and the second metal plate form a stable bonding state through the DW-3 low-temperature glue. There is no obvious glue layer penetration phenomenon during the secondary complete curing treatment, which solves the technical problem of glue layer penetration at the edge of the lap joint structure, and the thickness of the glue layer can be better controlled by using the adhesive process, and the flatness of the product is improved.

[0034] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The step flowchart of the preparation method of the adhesive process provided by an embodiment of the present application is shown in the figure;

[0036] Figure 2 The structure diagram of the sample with the lap joint structure provided by an embodiment of the present application connected with the lap joint mold is shown in the figure;

[0037] Figure 3 The temperature-time and strain-time curves of the DW-3 low-temperature glue in the curing process are drawn based on the data collected by the measuring device; Figure 1

[0038] The structure diagram of the measuring device and the autoclave for collecting the DW-3 low-temperature glue curing process data provided in step S10 shown in the figure; Figure 4

[0039] The structure diagram of the glue scraping tool provided in step S20 shown in the figure. Figure 5 Figure 1 BRIEF DESCRIPTION OF DRAWINGS

[0040] BRIEF DESCRIPTION OF DRAWINGS

[0041]

[0042] DETAILED DESCRIPTION

[0043] ​The embodiments of the present application will be described in detail below with reference to the drawings, but the present application can be limited and covered by various different embodiments according to the claims.

[0044] Please refer to Figure 1 and Figure 2 , the present application provides a bonding process of a sample with a lap joint structure, the bonding process is used for preventing the adhesive layer in the lap joint structure from bleeding out from the lap joint edge, the sample comprises a first metal plate 210, a second metal plate 220 which is arranged at one end of the first metal plate 210 and is bonded to the first metal plate 210 by DW-3 low-temperature adhesive, and the first metal plate 210 and the second metal plate 220 which are connected form the lap joint structure 230; wherein the bonding process comprises:

[0045] Step S10, providing DW-3 low-temperature adhesive, and obtaining the gel time of the DW-3 low-temperature adhesive by a preset method, wherein the gel time is the gel time corresponding to the curing process to be adopted for curing the DW-3 low-temperature adhesive;

[0046] In the embodiment, the process parameters of the curing process to be adopted include temperature parameters and pressure parameters, and the gel time is the gel time corresponding to the temperature parameters of the curing process to be adopted.

[0047] It can be understood that, when the gel time of the DW-3 low-temperature adhesive is obtained by the preset method, the setting of the pressure parameters is not involved, if the curing temperature in the temperature parameters is 60℃, the measured gel time is the gel time corresponding to the curing temperature 60℃, and if the curing temperature in the temperature parameters is 80℃, the measured gel time is the gel time corresponding to the curing temperature 80℃.

[0048] In the embodiment, the curing process to be adopted includes that the temperature parameters include: the first curing temperature is 60℃, the first temperature rising rate is 1.5℃ / min, and the first holding time is 480min.

[0049] The preset method includes:

[0050] 1) providing DW-3 low-temperature adhesive, and determining the curing process to be adopted for curing the DW-3 low-temperature adhesive;

[0051] In the present embodiment, the commercial purchase is DW-3 epoxy resin, including three components A, B and C, which need to be mixed according to the product manual (mass ratio 5:1:0.2). After mixing, vacuum degassing process is used to make the mixture more uniform and reduce small molecule bubbles. The vacuum degassing process includes: first segment program: vacuum 30kPa, time 10s; second segment program: vacuum 8kPa, speed 500r / min, time 15s; third segment program: vacuum 3kPa, speed 2000r / min, time 90s; fourth segment program: vacuum 30kPa, speed 500r / min, time 10s. The vacuum degassing equipment used is TMV-200T vacuum stirring degassing machine.

[0052] In the present embodiment, the first metal plate and the second metal plate are made of the same material as the metal cladding layer of the high-pressure gas cylinder. The curing process of the DW-3 low-temperature adhesive refers to the curing process used when the DW-3 low-temperature adhesive is used for bonding during the manufacture of the high-pressure gas cylinder lap joint sample. When determining the curing process to be used, the lap joint performance of the metal cladding layer should be considered.

[0053] In other embodiments, if DW-3 low-temperature adhesive is used to bond other devices, the curing process to be used is the curing process used when bonding the device. Similarly, when manufacturing a high-pressure gas cylinder, if other low-temperature adhesives are used, the corresponding curing process is also applicable. The purpose of this step is to obtain the gel point corresponding to the temperature parameter when the adhesive layer is cured.

[0054] Here, it can be understood that the curing process to be used is the curing process designed for the DW-3 low-temperature adhesive.

[0055] 2) Please refer to Figure 3 , a measuring device 300 for measuring the gel point of the DW-3 low-temperature adhesive is provided, which includes a measuring mold 310 with a containing space, DW-3 low-temperature adhesive contained in the containing space, an optical fiber grating sensor 320 and a thermocouple 330 completely immersed in the DW-3 low-temperature adhesive, an optical fiber demodulator 340 connected to the optical fiber grating sensor 320, and a data recorder 350 connected to the thermocouple 330, the optical fiber grating sensor 320 and the thermocouple 330 are arranged adjacent to each other so that the temperature experienced by both is the same;

[0056] In the present application, the FBG fiber grating sensor is used to measure the gel point of DW-3 cryogenic glue. The measuring mold 310 comprises a base plate 311, a template 312 arranged on the base plate 311, and a black glue blocking frame 313 arranged on the side of the template 312 away from the base plate 311. The template is made of polytetrafluoroethylene material. The black glue blocking frame 313 is a rectangular frame. The template 312 and the black glue blocking frame 313 jointly form an accommodating space with an open upper end, and the DW-3 cryogenic glue is accommodated in the accommodating space.

[0057] Specifically, the assembly process of the measuring device 300 is as follows: (1) select a flat aluminum plate mold as the base plate 311, and in order to avoid the aluminum plate material from expanding in the subsequent low-temperature glue heating and curing process and thereby affecting the accuracy of the DW-3 cryogenic glue strain measured by the fiber grating sensor, place a template 312 made of polytetrafluoroethylene material on the base plate 311; (2) set the black glue blocking frame 313 on the template, specifically set the glue blocking first edge 3131, the glue blocking second edge 3132, and the glue blocking third edge 3133 to prevent the low-temperature glue from flowing randomly during the subsequent curing process. The height of the black glue should be higher than the thickness of the DW-3 cryogenic glue layer, and the DW-3 cryogenic glue should completely immerse the fiber grating sensor 320 and the thermocouple 330; (3) paste the fiber grating sensor 320 in the black glue blocking frame 313. The optical fiber jumper 360 connecting the fiber grating sensor 320 and the optical fiber modulator 340 is drawn out from the fourth edge opposite to the glue blocking first edge 3131. At the same time, the thermocouple 330 is placed near the fiber grating sensor 320 (on the left side or the right side of the fiber grating sensor, and the distance between the fiber grating sensor and the thermocouple is 5-6 mm). The other end of the thermocouple 330 is drawn out from the fourth edge which is not blocked by the black glue. The fiber grating sensor 320 and the thermocouple 330 are arranged adjacently so that they experience the same temperature, thereby avoiding the problem that the use of the fiber grating sensor alone cannot distinguish whether the change in the fiber grating Bragg center wavelength is caused by temperature change or strain change, i.e., the strain and temperature cross-sensitivity problem; (4) paste yellow glue on the optical fiber jumper 360 and the thermocouple 330 near the edge of the template 312 perpendicular to the drawing direction to fix the positions of the fiber grating sensor 320 and the thermocouple 330, and block the fourth edge with black glue to form the glue blocking fourth edge 3134; (5) pour the DW-3 cryogenic glue which has been vacuum degassed into the black glue blocking frame 313. The DW-3 cryogenic glue should completely immerse the fiber grating and the thermocouple.

[0058] In the present embodiment, the measuring device further comprises a black glue pad 370 arranged on the base plate 311 and connected with the template 312. Based on the black glue pad 370, the DW-3 cryogenic glue is prevented from flowing out of the black glue blocking frame 313 during the curing process. Figure 3The thickness of the black rubber pad 370 gradually decreases from right to left, which is arranged to facilitate the transition of the fiber jumper and the thermocouple from the high plane to the low plane, avoiding damage.

[0059] 3) Place the measuring device 300 in the autoclave 400, cure the DW-3 low temperature glue according to the temperature parameters, and obtain the wavelength data collected by the fiber demodulator during the curing process and the temperature data collected by the data recorder during the curing process;

[0060] Specifically: the template is adhered to the substrate with yellow glue, and then the entire device is placed in the autoclave 400. The fiber jumper 360 is connected with the fiber demodulator 340 through the reserved hole of the autoclave 400 for collecting the wavelength change of the FBG Bragg center during the curing process of the low temperature glue; the thermocouple 330 is connected with the data recorder 350 for collecting the temperature of the DW-3 low temperature glue during the curing process, recording the start time of the experiment, setting the DW-3 low temperature glue curing process on the autoclave, heating at 60℃, heating rate 1.5℃ / min, holding for 480min, and then cooling with the furnace, recording the end time of the experiment.

[0061] 4) Based on the wavelength data and the temperature data, the strain data of the DW-3 low temperature glue is calculated, and the curing time corresponding to the turning point from the viscous flow state to the high elastic state in the strain data is taken as the gel time of the DW-3 low temperature glue.

[0062] The collected temperature data and the calculated strain data are shown in Figure 4 From Figure 4 It can be seen that at the beginning of the experiment, the DW-3 low temperature glue is in a viscous flow state, and the strain continuously decreases. At about 105min, the gel point appears, and then the crosslinking exothermic reaction occurs, at which time the strain begins to increase continuously, and the turning point from the viscous flow state to the high elastic state is the gel point (time 105min, temperature 61.3℃).

[0063] In this embodiment, the calculation formula of the strain data is as follows:

[0064] Δε=(Δλ-K T ΔT) / K ε

[0065] Wherein:

[0066] △λ- wavelength change;

[0067] KT- temperature sensitivity coefficient, 0.0095nm / ℃;

[0068] △T- temperature change;

[0069] Kε - fiber grating strain sensitivity coefficient, 0.0012 nm / με;

[0070] △ε - axial strain change.

[0071] Step S20, determining the pre-curing process of the DW-3 low-temperature glue based on the gel time, and performing first pre-curing treatment on the first metal plate coated with the DW-3 low-temperature glue and the first metal plate coated with the DW-3 low-temperature glue respectively according to the pre-curing process, to obtain the first metal plate and the second metal plate after pre-curing.

[0072] The gel time obtained in step S10 is 105 min, which includes heating time and holding time. The heating time is about 25 min calculated at a heating rate of 1.5℃ / min from 22 degrees to 60℃, and the holding time is about 80 min. However, in actual application, considering the factors such as the actual heat transfer between the hot air blown by the autoclave fan and the substrate and the polytetrafluoroethylene template, and the like, both good adhesion of the glue layer and gel phenomenon of the glue layer should be ensured. Therefore, the holding time of the pre-curing process is set to 105 min, which is better.

[0073] To verify the above conclusion, process test exploration is conducted on the gel point of the DW-3 low-temperature glue. Three groups of experiments are set, and the second complete curing process of the three groups of experiments is the curing process to be adopted. The difference mainly lies in that the process parameters of the pre-curing are not the same. The process parameters of the first group of experiments are set as curing temperature 60℃, heating rate 1.5℃ / min, and holding time 80 min. After the second complete curing of the lap joint sample, the glue layer of the edge of the lap joint sample is exuded. The process parameters of the second group of experiments are set as curing temperature 60℃, heating rate 1.5℃ / min, and holding time 100 min. After the second complete curing of the lap joint sample, the glue layer exuding phenomenon of the edge of the lap joint sample is not obvious. The process parameters of the third group of experiments are set as curing temperature 60℃, heating rate 1.5℃ / min, and holding time 110 min. After the second complete curing of the lap joint sample, the glue layer exuding phenomenon of the edge of the lap joint sample is not obvious. Based on the data of the above three groups of experiments, it is known that the holding time of the pre-curing process is 100-110 min, which can improve the glue layer exuding phenomenon of the edge of the lap joint sample.

[0074] Preferably, the process parameters of the pre-curing process include: the second curing temperature is 60℃, the second heating rate is 1.5℃ / min, and the second holding time is 100-110 min.

[0075] More preferably, the process parameters of the pre-curing process include: the second curing temperature is 60℃, the second heating rate is 1.5℃ / min, and the second holding time is 105 min.

[0076] Step S20 comprises:

[0077] 1) determining a pre-curing process, wherein the gel time is taken as the holding time of the pre-curing process, and the curing temperature and the temperature rising rate in the temperature parameters are taken as the curing temperature and the temperature rising rate of the pre-curing process respectively;

[0078] That is, the process parameters of the pre-curing process are: the second curing temperature is 60℃, the second temperature rising rate is 1.5℃ / min, and the second holding time is 105min.

[0079] 2) respectively pre-treating the first metal plate and the second metal plate, the pre-treatment comprising sandpaper polishing treatment and phosphoric acid anodizing treatment performed on the lap joint area of the first metal plate and the lap joint area of the second metal plate in sequence;

[0080] Herein, the lap joint area of the first metal plate and the lap joint area of the second metal plate refer to the areas where the first metal plate and the second metal plate are connected.

[0081] The purpose of the sandpaper polishing treatment is to form a protrusion or a concave profile on the lap joint area of the plate so as to enhance the mechanical bite performance of the glue layer and the plate. The phosphoric acid anodizing treatment is performed on the metal plate, and after anodizing, a porous honeycomb film of Al2O3 and other oxides is generated on the surface of the plate, thereby enhancing the adsorption capacity of the polar groups in the DW-3 low-temperature glue to the surface of the lap joint area of the plate.

[0082] 3) using a glue spreading tool to apply DW-3 low-temperature glue of a preset thickness on the lap joint area of the first metal plate and the lap joint area of the second metal plate respectively, the preset thickness being half of the target glue layer thickness;

[0083] In the present application, the DW-3 low-temperature glue applied on the lap joint area of the first metal plate and the lap joint area of the second metal plate is controlled to be half of the target glue layer thickness by using the glue spreading tool, and the target glue layer thickness is the designed glue layer thickness. For example, if the designed glue layer thickness for bonding the first metal plate and the second metal plate is 0.1mm, the target glue layer thickness is 0.1mm, and the glue layer thickness applied on the lap joint area of the first metal plate and the lap joint area of the second metal plate is 0.05mm respectively, so that after bonding, the glue layer thickness is 0.1mm.

[0084] In the present embodiment, the target glue layer thickness is 0.1mm, and the preset thickness is 0.05mm. In other embodiments, the target glue layer thickness can also be 0.2mm, 0.3mm, 0.4mm, etc.

[0085] Please refer to Figure 5In the embodiment, the glue scraping tool 500 comprises a bottom plate 510 and a glue scraping plate 520, the glue scraping plate 520 comprises a rectangular glue scraping plate body and a glue scraping groove formed by inwardly recessing from one end of the glue scraping plate body, the depth of the glue scraping groove is the thickness of the bottom plate 510 + the thickness of the glue plate + 1 / 2 of the target glue layer thickness, and the width of the glue scraping groove is slightly greater than the width of the glue plate.

[0086] The glue plate 600 is the first metal plate or the second metal plate.

[0087] In order to make the glue layer of the overlap region of the glue plate have a certain thickness and ensure that the DW-3 low-temperature glue fully infiltrates the overlap region of the sample, the glue layer coated glue plate is placed on the bottom plate 510, the region needing to be scraped is adjusted, the glue scraping plate 520 is placed, the glue scraping plate 520 needs to be placed vertically with the bottom plate 510, the glue plate 600 is pulled out horizontally along the glue scraping direction until the entire glue plate 600 is pulled out from the glue scraping tool, and the excess low-temperature glue is scraped off by the glue scraping plate 520, so as to ensure that the glue layer thickness of the coated glue layer 610 is half of the target glue layer thickness of the overlap region of the glue sample.

[0088] 4) The first metal plate coated with a preset thickness of DW-3 low-temperature glue and the second metal plate coated with a preset thickness of DW-3 low-temperature glue are placed in a hot press tank, and the DW-3 low-temperature glue is cured according to the pre-curing process to obtain the first metal plate and the second metal plate after pre-curing.

[0089] In the embodiment, the first metal plate and the second metal plate are simultaneously placed in the hot press tank for pre-curing, and in other embodiments, the first metal plate coated with DW-3 low-temperature glue and the second metal plate coated with DW-3 low-temperature glue can be separately pre-cured and formed, and the pre-curing processes of the two are the same, specifically: the first metal plate coated with DW-3 low-temperature glue or the second metal plate coated with DW-3 low-temperature glue is placed in a hot press tank for curing, heated to 60°C at a heating rate of 1.5°C / min, and then taken out after 105 min of insulation.

[0090] Step S30, connecting the first metal plate and the second metal plate after pre-curing to form a sample to be completely cured with an overlap structure, packaging the sample to be completely cured with a vacuum bag and placing it in a hot press tank, and performing a second complete curing treatment according to the curing process to be adopted to obtain the sample.

[0091] Please refer to Figure 2 , specifically, the step S30 comprises:

[0092] A lapping die 700 is provided, which comprises an aluminum plate 710, a thin backing plate 720 and multiple backing blocks 730, the thickness of the thin backing plate 720 is the target adhesive layer thickness, and the thickness of each of the multiple backing blocks 730 is the thickness of the first metal plate 210;

[0093] The first metal plate 210 and the thin backing plate 720 after pre-curing are placed on the aluminum plate, and the thin backing plate 720 is arranged close to the end of the first metal plate 210 coated with DW-3 low-temperature adhesive;

[0094] The multiple backing blocks 730 are arranged on the thin backing plate 720 in an interval to support the second metal plate 220;

[0095] The second metal plate 220 is placed on the multiple backing blocks 730, and the first end of the second metal plate 220 coated with DW-3 low-temperature adhesive is opposite to the area of the first metal plate 210 coated with DW-3 low-temperature adhesive for bonding, thereby forming a sample to be completely cured with a lapping structure;

[0096] The first metal plate 210, the second metal plate 220 and the lapping die 700 are packaged as a whole by a vacuum bag, and after vacuum treatment, they are placed in a hot press tank for second complete curing treatment according to the curing process to be adopted, thereby obtaining the sample, wherein the curing process to be adopted comprises: heating to 60℃ at a heating rate of 1.5℃ / min, and keeping at 60℃ for 480min, and then cooling with the furnace, and the vacuum bag is pumped to 0.1MPa vacuum during the whole curing process, and the hot press tank is pressurized to 0.05MPa.

[0097] In this step, vacuum treatment is performed, which can make the connection between the first metal plate and the second metal plate more closely.

[0098] In this embodiment, the number of the backing blocks is two.

[0099] Preferably, the sample provided by the present application is a glue joint pull-off sample, which is used to determine the lapping process corresponding to the best glue joint pull-off strength, and specifically includes lapping length, adhesive layer thickness, treatment method of the adhesive layer surface, etc.

[0100] The adhesive process of the sample with the lap joint structure provided by the application adopts a secondary curing molding process. The DW-3 low-temperature glue used for adhesion has good viscosity and gel performance in the first pre-curing process, that is, the low-temperature glue can keep the state of viscosity and at the same time can also take into account the poor flow characteristics. Then the first metal plate and the second metal plate are bonded to form a lap joint structure after the pre-curing process is completed. Finally, the first metal plate and the second metal plate are in a stable bonding state through the DW-3 low-temperature glue, and there is no glue layer bleeding during the secondary complete curing process. The technical problem of glue layer bleeding at the edge of the lap joint structure is solved. Moreover, the thickness of the glue layer can be better controlled by using the adhesive process, and the flatness of the product is improved.

[0101] The above is a further detailed description of the application in combination with specific preferred embodiments, and the specific implementation of the application cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the application belongs, some simple deductions and substitutions can be made without departing from the concept of the application, and all of them should be regarded as falling within the protection scope of the application.

Claims

1. A bonding process of a test sample having a lap joint structure for preventing bleed-out of a glue layer from a lap edge in the lap joint structure to control a thickness of the glue layer to a target glue layer thickness, the test sample including a first metal plate, a second metal plate having a first end lap on one end of the first metal plate and bonded to the first metal plate by a DW-3 low temperature glue, and the first metal plate and the second metal plate connected to each other to form the lap joint structure, characterized in that, The bonding process comprises: (1) providing DW-3 low-temperature glue, obtaining the gel time of the DW-3 low-temperature glue by a preset method, wherein the gel time is the gel time corresponding to the curing process to be adopted for curing the DW-3 low-temperature glue, and the process parameters of the curing process to be adopted include temperature parameters and pressure parameters, and the gel time is the gel time corresponding to the temperature parameters of the curing process to be adopted; (2) determining the pre-curing process of the DW-3 low-temperature glue based on the gel time, and performing first pre-curing treatment on the first metal plate coated with the DW-3 low-temperature glue and the second metal plate coated with the DW-3 low-temperature glue according to the pre-curing process, to obtain the first metal plate and the second metal plate after pre-curing, wherein the thickness of the DW-3 low-temperature glue coated on the overlap region of the first metal plate and the second metal plate is half of the target glue layer thickness; (3) connecting the first metal plate and the second metal plate after pre-curing to form a sample to be completely cured with an overlap structure, packaging the sample to be completely cured with a vacuum bag, and placing the sample to be completely cured in a hot press tank to perform second complete curing treatment according to the curing process to be adopted, to obtain the sample.

2. The bonding process of claim 1, wherein The temperature parameters include that the first curing temperature is 60℃, the first heating rate is 1.5℃ / min, and the first holding time is 480min; and the obtained gel time corresponding to the temperature parameters is 105min.

3. The bonding process of claim 2, wherein The process parameters of the pre-curing process in step (2) include that the second curing temperature is 60℃, the second heating rate is 1.5℃ / min, and the second holding time is 100-110min.

4. The bonding process of claim 1, wherein The preset method in step (1) comprises: providing DW-3 low-temperature glue, and determining the curing process to be adopted for curing the DW-3 low-temperature glue; providing a measuring device for measuring the gel point of the DW-3 low-temperature glue, wherein the measuring device comprises a measuring mold with an accommodation space, DW-3 low-temperature glue accommodated in the accommodation space, a fiber grating sensor and a thermocouple completely immersed in the DW-3 low-temperature glue, an optical fiber demodulator connected with the fiber grating sensor, and a data recorder connected with the thermocouple, the fiber grating sensor and the thermocouple are arranged adjacent to each other so that the temperatures experienced by the two are the same; placing the measuring device in a hot press tank, curing the DW-3 low-temperature glue according to the temperature parameters, obtaining wavelength data collected by the optical fiber demodulator during the curing process and temperature data collected by the data recorder during the curing process; based on the wavelength data and the temperature data, calculating the strain data of the DW-3 low-temperature glue, and taking the curing time corresponding to the turning point from the viscous flow state to the high-elastic state in the strain data as the gel time of the DW-3 low-temperature glue.

5. The bonding process of claim 4, wherein The measuring mold comprises a base plate, a template arranged on the base plate, and a black rubber blocking frame arranged on the side of the template away from the base plate, the template is made of polytetrafluoroethylene material, the black rubber blocking frame is a rectangular frame, and the template and the black rubber blocking frame jointly form the accommodating space with an open upper end.

6. The bonding process of claim 1, wherein The step (2) comprises: determining a pre-curing process, wherein the gel time is used as the holding time of the pre-curing process, and the curing temperature and the temperature rising rate in the temperature parameters are used as the curing temperature and the temperature rising rate of the pre-curing process, respectively; respectively pre-treating the first metal plate and the second metal plate, the pre-treatment comprising sandpaper polishing treatment and phosphoric acid anodizing treatment performed on the overlapping regions of the first metal plate and the second metal plate in sequence; applying DW-3 low-temperature glue with a preset thickness on the overlapping regions of the first metal plate and the second metal plate using a glue scraping tool, the preset thickness being half of the target glue layer thickness; placing the first metal plate coated with DW-3 low-temperature glue with a preset thickness and the second metal plate coated with DW-3 low-temperature glue with a preset thickness into a hot pressing tank, and curing the DW-3 low-temperature glue according to the pre-curing process to obtain the first metal plate and the second metal plate after pre-curing.

7. The bonding process of claim 6, wherein The step (3) comprises: providing a lapping mold comprising an aluminum plate, a thin backing plate, and multiple backing blocks, the thickness of the thin backing plate being the target glue layer thickness, and the thickness of each of the multiple backing blocks being the thickness of the first metal plate; placing the first metal plate after pre-curing and the thin backing plate on the aluminum plate, the thin backing plate being arranged close to one end of the first metal plate coated with DW-3 low-temperature glue; spacedly arranging multiple backing blocks on the thin backing plate to support the second metal plate; placing the second metal plate on the multiple backing blocks, and the overlapping region of the second metal plate coated with DW-3 low-temperature glue being opposite to and bonded with the overlapping region of the first metal plate coated with DW-3 low-temperature glue to form a sample to be completely cured with a lapping structure; packaging the lapped first metal plate and second metal plate, and the lapping mold as a whole with a vacuum bag, performing vacuum treatment, and then placing them in a hot pressing tank to perform second complete curing treatment according to the curing process to be adopted, wherein the curing process to be adopted comprises: increasing the temperature to 60℃ at a temperature rising rate of 1.5℃ / min, and holding at 60℃ for 480min, and then cooling with the furnace, and the vacuum bag is pumped to 0.1MPa vacuum, and the hot pressing tank is pressurized to 0.05MPa.

8. The bonding process of claim 7, wherein The target glue layer thickness is 0.1mm.

9. The bonding process of claim 1, wherein, The sample is a glued lapping sample.

Images