Production process of hardware spring with stable contact performance

Abstract

The application belongs to the technical field of hardware machining, and particularly relates to a production process of hardware spring piece with stable contact performance. The production process of the hardware spring piece with stable contact performance comprises the following steps: S1, casting raw materials to obtain initial samples; S2, after the initial samples are sequentially subjected to heat treatment and surface treatment, precision detection is performed, and the hardware spring piece is obtained after passing the detection. The corrosion resistance and contact performance of the hardware spring piece are improved through the measures of optimizing material selection and strengthening surface treatment. After the mechanical cycle test for millions of times, the hardware spring piece can still maintain excellent contact performance and stable electrical characteristics, so that the reliability and service life of the product are significantly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hardware processing, and particularly relates to a production process of hardware spring piece with stable contact performance. BACKGROUND

[0002] In the technical field of hardware spring piece, the stability and durability of contact performance have always been important technical indicators. Hardware spring pieces are widely used in mobile phone cards, mobile phone antennas, thin film switches, contact switches, PCB boards, FPC boards, medical devices, earphone audio jacks, connector pieces, micro motors, sensors, relay switches, digital 3C products, and automobile instrument light touch switches. However, the hardware spring pieces in the prior art often have the problem of decreased contact performance after long-term use due to material fatigue, surface wear or oxidation, which leads to unstable electrical connection and affects the reliability and service life of the product.

[0003] Although the traditional production process of hardware spring pieces can meet the basic manufacturing requirements to some extent, there are still deficiencies in improving the corrosion resistance and contact performance of the spring pieces. For example, some production processes lack fine control in aspects such as material selection, stamping forming, and surface treatment, which leads to deformation, wear or corrosion of the spring pieces after long-term use, thereby affecting the contact performance.

[0004] In order to solve the above problems, the application provides a production process of hardware spring piece with stable contact performance, which aims to improve the corrosion resistance and contact performance of the hardware spring piece. SUMMARY

[0005] The application aims to provide a production process of hardware spring piece with stable contact performance, which improves the corrosion resistance and contact performance of the hardware spring piece by optimizing material selection and strengthening surface treatment, and the hardware spring piece can still maintain excellent contact performance and stable electrical characteristics after millions of mechanical cycle tests, thereby significantly improving the reliability and service life of the product.

[0006] A production process of hardware spring piece with stable contact performance, comprising the following steps:

[0007] S1, casting and forming raw materials to obtain initial samples;

[0008] S2, after the initial samples are sequentially subjected to heat treatment and surface treatment, precision detection is performed, and the hardware spring piece is obtained after passing the detection.

[0009] Preferably, the raw material is any one of stainless steel, copper, and copper alloy.

[0010] Preferably, the copper alloy has the following elemental composition by weight percentage: Be: 0.5% to 3%, P: 0.05% to 0.2%, Sn: 1% to 3%, Zn: 2% to 4%, and the balance being Cu.

[0011] The inventors have found that by selecting a copper alloy as the raw material for the hardware bullet, and introducing specific proportions of metal elements Be, P, Sn, and Zn, the corrosion resistance of the hardware bullet can be improved, and at the same time, the mechanical properties of the hardware bullet can also be improved. This may be because, on the one hand, phosphorus can react with other impurities in copper to form high-melting-point compounds, thereby improving the thermal stability and corrosion resistance of the copper alloy; zinc can form a dense oxide film on the surface of the copper alloy, preventing the corrosion of corrosive media, and the synergistic effect of these elements makes the hardware bullet have excellent corrosion resistance. On the other hand, the addition of beryllium, tin, and zinc can significantly improve the strength and hardness of the copper alloy, and phosphorus can improve the flowability of the copper melt, which helps to improve the casting performance and shape stability of the copper alloy. The synergistic effect of these elements makes the hardware bullet have excellent mechanical properties, and can withstand a large external force and deformation without damage. In addition, copper, as the main component of the copper alloy, has good electrical conductivity. Although the addition of beryllium, phosphorus, tin, and zinc will affect the electrical properties of copper to some extent, such as contact resistance, when their content is controlled within an appropriate range, the effect on the electrical properties of the copper alloy is small, so that the hardware bullet can maintain good electrical properties while having high reliability and long service life, and can work stably in electronic equipment.

[0012] The specific steps of the casting forming are as follows:

[0013] A1, weighing copper ingots, tin ingots, zinc ingots, and Cu-P and Cu-Be intermediate alloys according to the weight percentage of the elements of the raw material;

[0014] A2, putting the copper ingots, tin ingots, zinc ingots, and Cu-P and Cu-Be intermediate alloys into an induction melting furnace, heating and stirring to obtain a melt;

[0015] A3, after refining, degassing, and stirring, the melt obtained in step A2 is allowed to stand and be kept for 8 to 12 minutes;

[0016] A4, transferring the melt obtained in step A3 to a hardware bullet-shaped mold that has been preheated, and cold stamping to form a preliminary sample.

[0017] Preferably, the weight percentage of each metal in the Cu-P and Cu-Be intermediate alloys is Cu-10P and Cu-2.0Be, respectively.

[0018] Preferably, the specific operation steps of step A2 are as follows: the smelting furnace is preheated to 400-500℃, copper ingots are added, heated to 1100-1150℃, and after complete melting, heat preservation is carried out for 15-25 min, the temperature is lowered to 1000-1100℃, tin ingots and zinc ingots are added, complete melting is carried out, and heat preservation is carried out for 15-25 min, the temperature is lowered to 900-1000℃, Cu-P intermediate alloy is added, complete melting is carried out, and heat preservation is carried out for 15-25 min, the temperature is raised to 1100-1200℃, Cu-Be intermediate alloy is added, complete melting is carried out, and heat preservation is carried out for 15-25 min, to obtain a melt.

[0019] In some preferred embodiments, by stepwise addition of raw materials for smelting and controlling the temperature, the performance of the shrapnel can be further improved. This may be because the melting points of the elements and their roles in the system are different. During heating, metal raw materials such as copper ingots, tin ingots, and zinc ingots gradually melt and mix uniformly in the smelting furnace. During this process, the temperature and composition of the melt change, but the main change is physical change; after adding Cu-P intermediate alloy and Cu-Be intermediate alloy, the elements in these alloys will react chemically with copper, tin, zinc, and other elements in the melt to form new compounds or solid solutions. These chemical reactions promote the alloying process, making the composition and microstructure of the melt more complex and stable. By stepwise addition of smelting, not only can the uniform distribution of each element in the shrapnel be ensured, reducing segregation and the formation of inclusions, but also the microstructure of the shrapnel can be optimized, thereby improving its mechanical properties, corrosion resistance, and electrical properties.

[0020] Preferably, the specific conditions of the cold stamping forming are as follows: the tonnage of the punch press is 90-110 tons, and the stamping speed is 30-50 times / min.

[0021] The specific steps of the heat treatment are as follows:

[0022] B1, heat the initial sample to 150-250℃ and heat preservation for 5-10 min, heat to 380-500℃ and heat preservation for 5-10 min, heat to 600-700℃ and heat preservation for 30-60 min, and cool to room temperature with the furnace;

[0023] B2, heat the B1 sample to 800-900℃ and heat preservation for 30-60 min, and rapidly cool to room temperature;

[0024] B3, heat the B2 sample to 300-450℃ and heat preservation for 2-4 h, and air cool to room temperature.

[0025] The inventors found that through a specific heat treatment process, internal stress can be eliminated while improving the performance of the metal spring. This may be because the step-by-step heating process in B1 step can effectively release the internal stress in the sample, reduce the thermal stress caused by sudden temperature changes, and facilitate the further diffusion and uniform distribution of elements in the alloy, reducing composition segregation, ensuring the stability and uniformity of the sample during high temperature treatment, and improving its mechanical properties. The high temperature holding and rapid cooling in B2 step further promotes the refinement and homogenization of the structure, enhancing the strength and hardness of the metal spring. The residual stress and dislocations generated during the rapid cooling process are eliminated or reduced during the tempering process in B3 step, improving the toughness and elasticity of the metal spring. Through a reasonable heat treatment process, the toughness and plasticity of the metal spring can be improved while ensuring the strength and hardness, improving the mechanical properties and service life of the metal spring, and optimizing the corrosion resistance and electrical performance.

[0026] Preferably, the specific steps of the surface treatment are as follows: after heat treatment, the sample is sequentially pickled, activated, and plated with nickel, and then obtained.

[0027] Preferably, the specific steps of the pickling are as follows: the sample is placed in the pickling solution for 5-10 min.

[0028] Preferably, the pickling solution is 10%-15% sulfuric acid or 5%-10% hydrochloric acid.

[0029] Preferably, the specific steps of the activation are as follows: the sample is placed in the activation solution for 5-10 min.

[0030] Preferably, the activation solution is a 0.1-0.2 g / L aqueous solution of palladium chloride.

[0031] Preferably, the specific steps of the nickel plating are as follows: the sample is placed in the plating solution, stirred for 30-60 min, then rinsed with deionized water to remove the residual nickel plating on the surface, and then dried.

[0032] Preferably, the formula of the plating solution is as follows: nickel sulfate 20-30 g / L, sodium hypophosphite 20-30 g / L, sodium citrate 10-20 g / L, boric acid 20-30 g / L, and sodium acetate to adjust the pH value to 4.5-5.0, with a use temperature of 80-90°C.

[0033] The inventors find that the initial sample after heat treatment is treated by using a plating solution with a specific formula, which can improve the corrosion resistance of the hardware bullet, and also improve the contact stability and maintain good electrical performance. This may be because the nickel sulfate provides a source of nickel ions, and the sodium hypophosphite acts as a reducing agent to reduce the nickel ions to metallic nickel and deposit on the substrate surface, and the synergistic effect between the two ensures the formation and quality of the nickel plating layer; sodium citrate as a complexing agent forms a stable complex with nickel ions to prevent premature precipitation of nickel ions, which helps to maintain the stability of the plating solution and ensure the uniformity and smoothness of the plating layer; boric acid as a buffer maintains the stability of the pH value of the plating solution, further enhancing the stability of the plating solution and ensuring the quality and uniformity of the plating layer. The synergistic effect of each component makes the plating layer uniform in thickness and fine in crystallization, which can protect the hardware bullet from corrosion and oxidation while maintaining its good electrical performance, and the bonding force between the plating layer and the substrate metal is good, making the hardware bullet more stable and reliable in connection and contact.

[0034] Preferably, the precision detection includes using high-precision detection equipment to detect the size and geometric tolerance of the prepared hardware bullet to ensure that it meets the design requirements.

[0035] The second aspect of the application provides a hardware bullet with stable contact performance prepared by the production process of the hardware bullet with stable contact performance.

[0036] Compared with the prior art, the application has the following advantages and beneficial effects:

[0037] 1. The application provides a hardware bullet with stable contact performance, which improves the corrosion resistance and contact performance of the hardware bullet by optimizing material selection and strengthening surface treatment, and after millions of mechanical cycle tests, the hardware bullet can still maintain excellent contact performance and stable electrical characteristics, thereby significantly improving the reliability and service life of the product.

[0038] 2. The application uses copper alloy as the raw material of the hardware bullet, and introduces metal elements Be, P, Sn and Zn in a specific proportion, which can improve the corrosion resistance of the hardware bullet while improving its mechanical properties.

[0039] 3. The application melts the raw materials by stepwise addition and controls the temperature, which can further improve the performance of the hardware bullet.

[0040] 4. The application can eliminate internal stress and improve the performance of the hardware bullet through a specific heat treatment step.

[0041] 5. The application uses a plating solution with a specific formula to treat the initial sample after heat treatment, which can improve the corrosion resistance of the hardware bullet while improving the contact stability and maintaining good electrical performance.

[0042] 6. The production process of the application is not only suitable for the manufacture of traditional metal bullet, but also can be widely applied to the manufacture of various bullet which needs high corrosion resistance and contact performance, and has broad market prospect and application value. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0044] Embodiment 1

[0045] The embodiment provides a production process of metal bullet with stable contact performance, and the steps are as follows: S1, casting and forming raw materials to obtain initial samples;

[0046] S2, after the initial samples are sequentially subjected to heat treatment and surface treatment, precision detection is performed, and the product is obtained after passing the detection.

[0047] The raw material is copper alloy, and the element components are Be: 2%, P: 0.1%, Sn: 2%, Zn: 3%, and the balance is Cu.

[0048] The specific steps of the casting and forming are as follows:

[0049] A1, copper ingots, tin ingots, zinc ingots, Cu-P and Cu-Be intermediate alloys are weighed according to the weight percentage of the elements of the raw material;

[0050] A2, the copper ingots, tin ingots, zinc ingots, Cu-P and Cu-Be intermediate alloys are put into an induction melting furnace, heated, stirred and kept warm to obtain a melt;

[0051] A3, after the melt obtained in step A2 is subjected to refining, deslagging and stirring, it is kept warm for 10 minutes.

[0052] A4, the melt obtained in step A3 is transferred to a preheated metal bullet-shaped mold for cold stamping and forming, and the initial sample is obtained.

[0053] The weight percentage of each metal in the Cu-P and Cu-Be intermediate alloy is Cu-10P and Cu-2.0Be, respectively.

[0054] The specific operation steps of step A2 are: preheat the smelting furnace to 450℃, add copper ingot, heat to 1120℃, after complete melting, keep warm for 20 min, cool to 1050℃, add tin ingot and zinc ingot, after complete melting, keep warm for 20 min, cool to 950℃, add Cu-P intermediate alloy, after complete melting, keep warm for 20 min, heat to 1150℃, add Cu-Be intermediate alloy, after complete melting, keep warm for 20 min, to obtain the melt.

[0055] The specific conditions of the cold stamping forming are: the tonnage of the punch is 100 tons, and the stamping speed is 40 times / min.

[0056] The specific steps of the heat treatment are:

[0057] B1, heat the initial sample to 200℃ and keep warm for 8 min, heat to 450℃ and keep warm for 8 min, heat to 650℃ and keep warm for 40 min, and cool to room temperature with the furnace;

[0058] B2, heat the B1 sample to 850℃ and keep warm for 40 min, and quickly cool to room temperature;

[0059] B3, heat the B2 sample to 380℃ and keep warm for 3h, and air cool to room temperature.

[0060] The specific steps of the surface treatment are: after the heat treatment, the sample is sequentially pickled, activated, and plated with nickel, and then obtained.

[0061] The specific steps of the pickling are: the sample is placed in hydrochloric acid with a mass concentration of 8% for 8 min.

[0062] The specific steps of the activation are: the sample is placed in a palladium chloride aqueous solution with a mass concentration of 0.15g / L for 8 min.

[0063] The specific steps of the nickel plating are: the sample is placed in the plating solution, stirred for 40 min, then rinsed with deionized water to remove the residual nickel plating on the surface, and then dried.

[0064] The formula of the plating solution is: nickel sulfate 25g / L, sodium hypophosphite 25g / L, sodium citrate 15g / L, boric acid 25g / L, and sodium acetate is used to adjust the pH value to 4.5, and the use temperature is 85℃.

[0065] Example 2

[0066] The difference between this example and example 1 is that the raw material is a copper alloy, and the element composition is Be: 2.5%, P: 0.1%, Sn: 2.5%, Zn: 2.5%, and the balance is Cu.

[0067] Example 3

[0068] The difference between the present example and Example 1 is that the plating solution is formulated as follows: nickel sulfate 28 g / L, sodium hypophosphite 23 g / L, sodium citrate 16 g / L, boric acid 27 g / L, and sodium acetate is used to adjust the pH value to 4.5, and the temperature for use is 85°C.

[0069] Comparative Example 1

[0070] The difference between the present comparative example and Example 1 is that the raw material is a copper alloy, and the elemental composition is, by weight percentage, Be: 2%, P: 0.1%, Sn: 2%, Zn: 6%, and the balance being Cu.

[0071] Comparative Example 2

[0072] The difference between the present comparative example and Example 1 is that the raw material is a copper alloy, and the elemental composition is, by weight percentage, Be: 2%, P: 0.1%, Zn: 3%, and the balance being Cu.

[0073] Comparative Example 3

[0074] The difference between the present comparative example and Example 1 is that the specific operation steps of Step A2 are as follows: the smelting furnace is preheated to 400-500°C, the raw material is added, heated to 1100-1150°C, and after complete melting, the melt is obtained after holding for 35-45 min.

[0075] Comparative Example 4

[0076] The difference between the present comparative example and Example 1 is that the specific steps of the heat treatment are as follows: the initial sample is heated to 150-250°C and held for 5-10 min, heated to 380-500°C and held for 5-10 min, heated to 600-700°C and held for 30-60 min, and then cooled to room temperature in the furnace.

[0077] Comparative Example 5

[0078] The difference between the present comparative example and Example 1 is that the specific steps of the heat treatment are as follows:

[0079] B1, the initial sample is heated to 600-700°C and held for 30-60 min, and then cooled to room temperature in the furnace;

[0080] B2, the sample of B1 is heated to 800-900°C and held for 30-60 min, and then rapidly cooled to room temperature;

[0081] B3, the sample of B2 is heated to 300-450°C and held for 2-4 h, and then air-cooled to room temperature.

[0082] Comparative Example 6

[0083] The difference between the present comparative example and example 1 is that the plating solution is formulated as follows: nickel sulfate 25 g / L, sodium hypophosphite 25 g / L, boric acid 25 g / L, and the pH value is adjusted to 4.5 by sodium acetate, and the use temperature is 85°C.

[0084] Comparative example 7

[0085] The difference between the present comparative example and example 1 is that the plating solution is formulated as follows: nickel sulfate 25 g / L, sodium hypophosphite 25 g / L, boric acid 25 g / L, and the pH value is adjusted to 4.5 by sodium acetate, and the use temperature is 85°C.

[0086] Performance test

[0087] The prepared hardware shrapnel is soaked in a 3.5% NaCl aqueous solution for seven days, and the corrosion rate is tested. The contact resistance is measured by a contact resistance tester, and the contact resistance should be ≤10 mΩ. The mechanical cycle test is performed by a metal shrapnel button impact life tester, and the contact resistance after 100 million cycles should be no more than 15 mΩ. The results are shown in Table 1.

[0088] Table 1 test results

[0089]

[0090] According to statistics, the corrosion rate and contact resistance of the hardware shrapnel prepared in examples 1-3 are low, and the contact resistance remains at about 10 mΩ after 100 million mechanical cycles, indicating that the prepared hardware shrapnel has excellent corrosion resistance, electrical performance and contact stability. Comparative example 1 adds excess Zn, comparative example 2 does not add Sn, comparative example 3 does not perform step-by-step smelting, comparative example 4 lacks B2 and B3 heat treatment steps, comparative example 5 does not perform step-by-step temperature rising treatment in heat treatment step B1, and comparative example 6 does not add sodium hypochlorite, and comparative example 7 adds too little nickel sulfate and sodium hypophosphite, so the hardware shrapnel prepared has poor performance. Therefore, the hardware shrapnel prepared by the raw materials and method described in the present application has high corrosion resistance, excellent electrical performance and stable contact performance, thereby significantly improving the reliability and service life of the product.

[0091] The above is a preferred embodiment of the present application. It should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A manufacturing process for a metal spring with stable contact performance, characterized in that, Includes the following steps: S1. Cast the raw material into a preliminary sample; S2. Heat-treat the initial sample, then pickle, activate, and nickel-plat the heat-treated sample in sequence, and perform precision testing. Once the sample passes the test, it is considered qualified. The raw material is a copper alloy, and its elemental composition by weight percentage is: Be: 0.5%–3%, P: 0.05%–0.2%, Sn: 1%–3%, Zn: 2%–4%, with the balance being Cu; The specific steps of the casting process are as follows: A1. Weigh out copper ingots, tin ingots, zinc ingots, and Cu-P and Cu-Be master alloys according to the weight percentage of the elements in the raw materials. A2. Preheat the melting furnace to 400-500℃, add copper ingots, heat to 1100-1150℃, and hold for 15-25 minutes after complete melting. Cool down to 1000-1100℃, add tin and zinc ingots, and hold for 15-25 minutes after complete melting. Cool down to 900-1000℃, add Cu-P master alloy, and hold for 15-25 minutes after complete melting. Heat up to 1100-1200℃, add Cu-Be master alloy, and hold for 15-25 minutes after complete melting to obtain the melt. A3. After refining, degassing, removing slag, and stirring the melt obtained in step A2, let it stand and keep it at a constant temperature for 8 to 12 minutes. A4. Transfer the melt obtained in step A3 into a preheated metal spring-shaped mold and cold stamp it to form the initial sample. The specific steps of the heat treatment are as follows: B1. Heat the initial sample to 150-250℃ and hold for 5-10 minutes, then heat to 380-500℃ and hold for 5-10 minutes, then heat to 600-700℃ and hold for 30-60 minutes, and then cool to room temperature with the furnace. B2. Heat sample B1 to 800-900℃ and hold for 30-60 minutes, then rapidly cool to room temperature; B3. Heat sample B2 to 300-450℃ and keep it at that temperature for 2-4 hours, then cool it to room temperature. The nickel plating solution formula is as follows: nickel sulfate 20-30 g / L, sodium hypophosphite 20-30 g / L, sodium citrate 10-20 g / L, boric acid 20-30 g / L, sodium acetate to adjust the pH value to 4.5-5.0, and the operating temperature is 80-90℃.

2. The manufacturing process of the metal spring with stable contact performance according to claim 1, characterized in that, The weight percentages of each metal in the Cu-P and Cu-Be master alloys are Cu-10P and Cu-2.0Be, respectively.

3. The manufacturing process of the metal spring with stable contact performance according to claim 1, characterized in that, The specific conditions for cold stamping are: the press tonnage is 90 to 110 tons, and the stamping speed is 30 to 50 times / min.

4. The manufacturing process of the metal spring with stable contact performance according to claim 1, characterized in that, The specific steps of the pickling process are as follows: place the sample in the pickling solution for 5 to 10 minutes.

5. The manufacturing process of the metal spring with stable contact performance according to claim 4, characterized in that, The pickling solution is sulfuric acid with a mass concentration of 10% to 15% or hydrochloric acid with a mass concentration of 5% to 10%.

6. The manufacturing process of the metal spring with stable contact performance according to claim 1, characterized in that, The specific steps for nickel plating are as follows: place the sample in the plating solution, stir and plate nickel for 30 to 60 minutes, rinse the surface with deionized water to remove residual nickel, and then dry.

7. The manufacturing process of the metal spring with stable contact performance according to claim 1, characterized in that, The specific activation steps are as follows: place the sample in the activation solution for 5 to 10 minutes; the activation solution is an aqueous solution of palladium chloride with a mass concentration of 0.1 to 0.2 g / L.

8. The manufacturing process of the metal spring with stable contact performance according to claim 1, characterized in that, The precision inspection includes using high-precision inspection equipment to inspect the dimensions and geometric tolerances of the manufactured metal springs to ensure that they meet the design requirements.

9. A metal spring sheet prepared by a manufacturing process for a metal spring sheet with stable contact performance according to any one of claims 1 to 8.

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