CN114083813A

CN114083813A - Instrument shell and production process thereof

Info

Publication number: CN114083813A
Application number: CN202111366326.2A
Authority: CN
Inventors: 金子豪; 段海涯; 朱坚
Original assignee: Hangzhou Shunhao Metalwork Co ltd
Current assignee: Hangzhou Shunhao Metalwork Co ltd
Priority date: 2021-11-18
Filing date: 2021-11-18
Publication date: 2022-02-25

Abstract

The invention relates to an instrument shell and a production process thereof, belonging to the technical field of novel composite materials. The instrument shell is made of a composite material and specifically comprises a core shell, an electrostatic shielding adhesive layer on the surface of the core shell and a carbon glass fiber cloth layer on the surface layer, the composite structure is convenient to process, is suitable for a complex structure, has a good electrostatic shielding effect, is flame-retardant and wear-resistant, and can be applied to the working condition of high temperature and high ion current density; according to the electrostatic shielding adhesive, the conductive filler is added into the epoxy resin diluent adhesive in a composite diluent mode to form a plurality of enrichment units, and then the enrichment units are dispersed into the epoxy resin to form a mutually-contacted net chain structure, so that current carriers can freely move in the net chain, and generated static electricity is led out in time.

Description

Instrument shell and production process thereof

Technical Field

The invention belongs to the technical field of novel composite materials, and particularly relates to an instrument shell and a production process thereof.

Background

The instrument shell generally comprises elements such as a shell, a panel, a lining plate and a support, and is used for loading and protecting detection elements, different functions are required according to different actual application occasions, and the common instrument shell comprises a metal instrument shell, a plastic instrument shell and a steel-plastic composite instrument shell.

The metal shell has the advantages of good shielding effect, high strength and the like, but the processing process is complex, the difficulty is high, the efficiency is low, the cost is high, the plasticity is poor, the corrosion resistance is poor, the plastic shell is convenient to process, is integrally formed, is simple in design and rich in modeling, but the electromagnetic shielding capability is poor, the metal shell is difficult to apply to the environment with strong electromagnetic field or high ion current strength, and the existing steel-plastic composite instrument shell is difficult to be uniformly improved in electromagnetic shielding and strength performance.

Disclosure of Invention

In order to solve the technical problems mentioned in the background art, the invention aims to provide an instrument shell and a production process thereof.

The purpose of the invention can be realized by the following technical scheme:

a production process of an instrument shell comprises the following steps:

step S1: stamping a 201 stainless steel sheet according to design requirements to form a blank shell;

step S2: shot blasting is simultaneously carried out on the inner surface and the outer surface of the blank shell by adopting a double-head shot blasting machine, the blank shell is strengthened, the strength of the blank shell is improved, uniform pits are formed on the surface, coating hanging is facilitated, then the shot blasting surface of the blank shell is cleaned by adopting a steel wire brush, surface residues are removed, then the cleaned blank shell is placed into an immersion liquid for immersion treatment, micro corrosion is formed on the inner surface and the outer surface of the blank shell, a layer of rough conversion film is formed, finally, the blank shell after the immersion treatment is washed by water, the immersion liquid remained on the surface is removed, and hot air drying is carried out, so that a core shell is obtained;

step S3: spraying electrostatic shielding glue on the surface of the core shell, standing for sagging, pre-curing by hot air, then paving carbon glass fiber cloth on the surface of the electrostatic shielding glue, pre-pressing the carbon glass fiber cloth and the electrostatic shielding glue for molding through a bag pressing process to obtain a composite shell, then putting the composite shell into a mold for hot press molding, taking out after molding, and machining according to functional requirements to obtain the instrument shell.

Further, the impregnation liquid comprises fluozirconic acid, phosphoric acid, ethylenediaminetetraacetic acid tetrasodium salt, phytic acid, absolute ethyl alcohol and water, and the dosage ratio is 18 g: 9.5 g: 4.7 g: 5.1 g: 50mL of: 2L, and adjusting the pH value to 3 with sulfuric acid to prepare impregnation liquid.

Further, the spraying thickness of the electrostatic shielding glue is 3 +/-0.5 mm.

Further, the temperature of hot air pre-curing is 60 +/-5 ℃, and the hot air pre-curing is carried out until the hardness of the electrostatic shielding adhesive is 20A.

Further, the pressure of hot-press molding is 2MPa, the temperature is 120 ℃, and the temperature is kept for 1 h.

The electrostatic shielding adhesive is prepared by the following steps:

step A1: stirring the conductive filler, the reinforcing additive and absolute ethyl alcohol at a high speed to form a suspension, and then adding a silane coupling agent and a diluent into the suspension for ultrasonic dispersion to obtain a composite diluent;

step A2: taking epoxy resin and a diluent, stirring and mixing until the viscosity is adjusted to be 6 +/-0.5 Pa.s to obtain epoxy resin diluted glue, then adding a composite diluent under a stirring state, then vacuumizing and heating to 35 +/-3 ℃, removing absolute ethyl alcohol, adding a curing agent and the diluent after pressure release, stirring again and adjusting the viscosity of the mixture to be 2.5 +/-0.2 Pa.s, and then vacuumizing again to remove bubbles to obtain the electrostatic shielding glue.

Further, the conductive filler comprises acetylene black, conductive graphite and nano copper powder, and the dosage and mass ratio is 1: 0.85-0.95:0.4-0.6, and the addition amount of the conductive filler in the epoxy resin diluent is 4.7-5.1 g/L.

Furthermore, the reinforcing auxiliary agent comprises one or more of polytetrafluoroethylene micro powder, nano silicon dioxide and silicon oxide whiskers which are mixed according to any proportion, and the dosage of the reinforcing auxiliary agent in the epoxy resin diluent is not more than 0.21 wt%.

Further, the silane coupling agent is a silane coupling agent KH560, the dosage of the silane coupling agent KH560 in the epoxy resin diluent is 6-8mL/L, and the pH value of the silane coupling agent KH560 is adjusted to 4 by adopting acetic acid before use.

Further, the diluent is butyl glycidyl ether, and in the step A1, the amount of the butyl glycidyl ether in the epoxy resin diluent is 50-100 mL/L.

Further, the carbon glass fiber cloth is formed by stacking a carbon fiber prepreg cloth and a layer of glass fiber prepreg cloth, is pressurized to 3MPa at 100 ℃, is kept warm for 2 hours, and is subjected to hot press molding, and one side of the glass fiber prepreg cloth is attached to the electrostatic shielding adhesive when in use.

The invention has the beneficial effects that:

1. the invention provides a composite material structure for an instrument shell, wherein a core shell in the middle is made of 201 stainless steel materials, the composite material structure has good strength and plasticity combination, a relatively complex shell can be manufactured by the existing stamping technology, an interlayer is an epoxy resin-based adhesive layer, the composite material structure has a good electrostatic shielding effect, an outer layer is carbon glass fiber cloth, and the composite material structure is flame-retardant and wear-resistant and effectively protects the epoxy resin-based adhesive layer, so that the instrument shell is applied to the working condition of high temperature and high ion current density.

2. The invention provides an electrostatic shielding adhesive, which is characterized in that conductive filler is added into epoxy resin diluent in a composite diluent mode, the composite diluent is stirred into a plurality of enrichment units in the epoxy resin diluent at the initial stage of addition, the conductive filler is dispersed into epoxy resin while the butyl glycidyl ether in the composite diluent is used for diluting the epoxy resin diluent to form a mutually-contacted net chain structure, current carriers can freely move in the net chain, nano copper powder is added into the conductive filler, precipitation is generated under the action of gravity in the standing and sagging process after the electrostatic shielding adhesive is sprayed, an enrichment area is formed at the bottom of the electrostatic shielding adhesive layer, a gradient is formed from bottom to top, and generated static electricity is timely led out.

3. The invention provides a method for processing a blank shell, which strengthens the blank shell by shot blasting on the inner surface and the outer surface simultaneously, and is favorable for hanging and covering electrostatic shielding glue because the two surfaces are stressed uniformly, the deformation of the blank shell is smaller and uniform tiny pits are formed; the dipping solution is provided, the surface of the blank shell is slightly corroded in an acid environment, and then a rough conversion film is formed on the blank shell by the aid of fluorozirconic acid and phosphoric acid under the synergistic effect of the auxiliary agents, so that the bonding strength of the electrostatic shielding adhesive and the core shell is further enhanced.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

In this embodiment, an electrostatic shielding adhesive is prepared, and the specific implementation process is as follows:

step A1: adding epoxy resin E-44 (hereinafter referred to as epoxy resin) into a stirrer, slowly adding butyl glycidyl ether into the stirrer in a stirring state, diluting the epoxy resin until the viscosity reaches 6Pa.s and the allowable error is 0.5Pa.s, preparing epoxy resin diluent, and taking 100L of epoxy resin diluent for later use;

step A2: screening acetylene black, conductive graphite and nano copper powder by a 1000-mesh screen, dispersing agglomerates in the raw materials, and then mixing the raw materials according to the mass ratio of 1: 0.85:0.6, and uniformly mixing in a pneumatic mixer to prepare conductive fillers; sieving polytetrafluoroethylene micro powder and nano silicon dioxide by a 1000-mesh sieve, and uniformly mixing in a pneumatic mixer according to the dosage-mass ratio of 1:1 to prepare a reinforcing auxiliary agent;

step A3: adding 470g of conductive filler and a reinforcing aid with the diluted epoxy resin colloid content of 0.21% into 8L of absolute ethyl alcohol, and stirring at the rotating speed of 1200rmp for 10min to form a suspension; adding acetic acid into 600mL of silane coupling agent KH560 to adjust the pH value to 4, reducing the stirring speed of the suspension to 360rmp, adding silane coupling agent KH560 and 5L of butyl glycidyl ether which are used for adjusting the pH value into the suspension, increasing the stirring speed to 800rmp, continuously stirring for 5min, and then ultrasonically dispersing the mixed solution at 28kHZ for 10min to obtain a composite diluent;

step A4: stirring 100L of epoxy resin diluted glue at 300rmp, adding a composite diluent into the epoxy resin diluted glue, uniformly dispersing conductive filler and a reinforcing aid in the composite diluent, stirring the composite diluent into a plurality of enrichment units in the epoxy resin diluted glue at the initial stage of adding, dispersing the conductive filler and the reinforcing aid into the epoxy resin while diluting the epoxy resin diluted glue by butyl glycidyl ether in the composite diluent, continuously stirring for 10min after completely adding, vacuumizing the mixture to 1kPa and heating to 35 +/-3 ℃, keeping the temperature and pressure for 1h, removing ethanol, then continuously stirring, adding a mixture of butyl glycidyl ether and methyl tetrahydrophthalic anhydride into the mixture, supplementing the butyl glycidyl ether until the viscosity of the mixture is 2.5 +/-0.2 Pa.s, vacuumizing again and defoaming to obtain the electrostatic shielding glue.

Example 2

step A1: adding epoxy resin E-44 (hereinafter referred to as epoxy resin) into a stirrer, slowly adding butyl glycidyl ether into the stirrer in a stirring state, diluting the epoxy resin until the viscosity reaches 6Pa.s and the allowable error is 0.5Pa.s, preparing epoxy resin diluent glue, and taking 100L of epoxy resin diluent glue for later use;

step A2: screening acetylene black, conductive graphite and nano copper powder by a 1000-mesh screen, dispersing agglomerates in the raw materials, and then mixing the raw materials according to the mass ratio of 1: 0.95:0.4, uniformly mixing in a pneumatic mixer to prepare conductive filler; sieving polytetrafluoroethylene micro powder and silicon oxide whiskers through a 1000-mesh sieve, and then uniformly mixing in a pneumatic mixer according to the dosage mass ratio of 1:1 to prepare a reinforcing auxiliary agent;

step A3: adding 510g of conductive filler and a reinforcing aid with 0.21% of epoxy resin diluted colloid weight into 6L of absolute ethyl alcohol, and stirring at 1200rmp for 15min to form a suspension; adding acetic acid into 800mL of silane coupling agent KH560 to adjust the pH value to 4, reducing the stirring speed of the suspension to 360rmp, adding the silane coupling agent KH560 and 10L of butyl glycidyl ether into the suspension to adjust the pH value, increasing the stirring speed to 800rmp, continuously stirring for 5min, and ultrasonically dispersing the mixed solution at 28kHZ for 15min to obtain a composite diluent;

Example 3

The carbon glass fiber cloth prepared in the embodiment is specifically implemented as follows:

putting HM-20 carbon fiber prepreg cloth on a mold, paving glass fiber prepreg cloth (with the thickness of 0.2mm) on the HM-20 carbon fiber prepreg cloth, heating to 100 ℃, slowly pressurizing to 3MPa, keeping the temperature and pressure for 2h, and bonding the HM-20 carbon fiber prepreg cloth and the glass fiber prepreg cloth together to obtain the carbon glass fiber cloth, wherein the HM-20 carbon fiber prepreg cloth and the glass fiber prepreg cloth are both pre-impregnated with epoxy resin.

Example 4

In this example, a slot instrument housing is prepared, and the specific implementation process is as follows:

step S1: taking a 201 stainless steel thin plate with the thickness of 2mm, and pressing the thin plate into a groove-shaped blank shell by adopting a punching machine;

step S2: shot blasting is simultaneously carried out on the inner surface and the outer surface of the blank shell by adopting a double-head shot blasting machine, the blank shell is strengthened, the strength of the blank shell is improved, meanwhile, shot blasting is simultaneously carried out on the two surfaces of the blank shell, so that the blank shell is uniformly deformed, uniform pits are formed on the surface, electrostatic shielding glue coating is facilitated, the coating efficiency is improved, the sagging amount is reduced, the raw material waste is reduced, and then the shot blasting surface of the blank shell is cleaned by adopting a steel wire brush, and surface residues are removed;

taking 18g of fluorozirconic acid, phosphoric acid, ethylenediaminetetraacetic acid tetrasodium, phytic acid, anhydrous ethanol and water in turn according to the dosage ratio: 9.5 g: 4.7 g: 5.1 g: 50mL of: 2L of the raw materials are mixed, concentrated sulfuric acid with the mass fraction of 70% is added to adjust the pH value of the mixed solution to be 3 to obtain an immersion liquid, the cleaned blank shell is placed into the immersion liquid to be immersed for 1.5h, the inner surface and the outer surface of the blank shell are subjected to micro corrosion to form a layer of rough conversion film, on one hand, the blank shell is protected, on the other hand, the bonding strength of the electrostatic shielding adhesive and the blank shell is improved, finally, the immersed blank shell is removed, the immersion liquid remaining on the surface is removed by washing with water, and hot air drying is carried out to obtain a core shell;

step S3: spraying the electrostatic shielding adhesive prepared in the embodiment 1 on the surface of a core shell by using a pressurizing spray gun to form an electrostatic shielding adhesive layer with the thickness of 3 +/-0.5 mm, standing, sagging, pre-curing in a hot air environment at 60 +/-5 ℃, and after curing to the hardness of 20A, attaching one side of the glass fiber pre-impregnated cloth of the carbon glass fiber cloth prepared in the embodiment 3 to the surface of the electrostatic shielding adhesive by using a bag pressing process to obtain a composite shell, then putting the composite shell into a mold, heating to 120 ℃, pressurizing to 2MPa, preserving heat and maintaining pressure for 1h, cooling to 50 ℃ along with the mold, demolding, cooling to room temperature, and machining according to the installation requirements of instruments to obtain the instrument shell.

Example 4

This example was carried out in the same manner as in example 3 except that the electrostatic shielding paste prepared in example 1 was replaced with the electrostatic shielding paste prepared in example 2.

The instrument housings prepared in examples 3-4 were sampled for surface resistivity testing with reference to the general specification of GJB2604-96 military electromagnetic shielding materials, and the specific data are shown in table 1:

TABLE 1

	Example 3	Example 4
			Surface resistivity (k.OMEGA./cm)²)	0.41	0.39

As can be seen from Table 1, the instrument housing prepared according to the present invention has a surface resistivity of 0.39 to 0.41 kOmega/cm²The conductive filler is added into the epoxy resin diluent in a composite diluent mode, the composite diluent is stirred into a plurality of enrichment units in the epoxy resin diluent at the initial addition stage, the butyl glycidyl ether in the composite diluent disperses the conductive filler into the epoxy resin while diluting the epoxy resin diluent to form a mutually-contacted network chain structure, and a carrier can freely move in a network chain.

The instrument housings prepared in examples 3-4 were subjected to a cross-cut test without laying carbon fiberglass cloth, referred to ISO2409:19928, using a single edge cutting tool at uniform cutting rates at intervals of 3mm, all cuts penetrating the core housing surface, the specific test data are shown in table 2:

TABLE 2

	Example 3	Example 4
			Grade of adhesion	Level 0	Level 1

As can be seen from Table 2, the electrostatic shielding adhesive prepared by the invention has excellent bonding strength with the core shell, and the adhesion grades are 0 grade and 1 grade.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.

Claims

1. The production process of the instrument shell is characterized by comprising the following steps of:

step S1: stamping a stainless steel sheet to form a blank shell;

step S2: shot blasting is carried out on the two sides of the blank shell simultaneously, surface residues are brushed off, then the blank shell is soaked in a soaking solution, and then the blank shell is washed and dried to obtain a core shell;

step S3: spraying electrostatic shielding glue on the surface of the core shell, standing, sagging, pre-curing by hot air until the hardness of the electrostatic shielding glue is 20A, paving carbon glass fiber cloth on the surface of the electrostatic shielding glue, pre-pressing and molding the carbon glass fiber cloth and the electrostatic shielding glue by a bag pressing process to obtain a composite shell, and finally performing compression molding and machining on the composite shell to obtain the meter shell.

2. The process for producing an instrument housing as claimed in claim 1, wherein the impregnating solution comprises fluorozirconic acid, phosphoric acid, tetrasodium ethylenediaminetetraacetate, phytic acid, absolute ethyl alcohol and water in the following order of 18 g: 9.5 g: 4.7 g: 5.1 g: 50mL of: 2L of the mixture was mixed and adjusted to pH 3 with sulfuric acid to prepare a dipping solution.

3. The process for manufacturing an instrument housing as claimed in claim 1, wherein the electrostatic shielding paste is sprayed to a thickness of 3 ± 0.5 mm.

4. The process for manufacturing an instrument shell according to claim 1, wherein the carbon-glass fiber cloth is formed by stacking a carbon fiber prepreg and a glass fiber prepreg and hot-pressing the carbon fiber prepreg and the glass fiber prepreg.

5. The process for manufacturing an instrument housing as claimed in claim 1, wherein the electrostatic shielding paste is prepared by the steps of:

step A1: stirring conductive filler, a reinforcing additive and absolute ethyl alcohol to form a suspension, and then adding a silane coupling agent and a diluent into the suspension for ultrasonic dispersion to obtain a composite diluent;

step A2: and (2) stirring and mixing epoxy resin and a diluent until the viscosity is adjusted to be 6 +/-0.5 Pa.s to obtain epoxy resin diluted glue, then adding the composite diluent under the stirring state, vacuumizing, heating to 35 +/-3 ℃, removing absolute ethyl alcohol, adding the curing agent and the diluent after pressure release, stirring again and adjusting the viscosity of the mixture to be 2.5 +/-0.2 Pa.s, and then vacuumizing again to remove bubbles to obtain the electrostatic shielding glue.

6. The instrument shell production process according to claim 5, wherein the conductive filler comprises acetylene black, conductive graphite and nano copper powder, and the mass ratio of the used amount is 1: 0.85-0.95:0.4-0.6, and the amount of the conductive filler in the epoxy resin diluent is 4.7-5.1 g/L.

7. The process for producing an instrument housing as claimed in claim 5, wherein the reinforcing aid comprises one or more of polytetrafluoroethylene micropowder, nano-silica, and silica whiskers mixed in an arbitrary ratio, and the amount of the reinforcing aid in the epoxy resin diluent is not more than 0.21 wt%.

8. The process for producing an instrument housing as claimed in claim 5, wherein the diluent is butyl glycidyl ether, and in step A1, the ratio of the diluent to the epoxy resin diluent is 50-100 mL/L.

9. An instrument housing, characterized by being produced by the production process as claimed in any one of claims 1 to 8.