Bolt manufacturing method

Abstract

The invention provides a bolt manufacturing method. The bolt manufacturing method comprises the steps that S1, a preset type of alloy material is formed into a bolt blank through warm upsetting machining; s2, grinding and thread rolling are conducted on the bolt blank to manufacture a bolt; s3, the bolt blank is subjected to solution treatment; s4, aging treatment is conducted on the bolt blank; and S5, the bolt blank is subjected to rolling treatment, and the bolt is manufactured. The defects of traditional hot and cold forming are avoided through warm upsetting machining, and the material utilization rate and the product stability are improved; the dimensional precision and the surface quality are ensured through grinding and thread rolling; various properties are improved through solid solution and aging treatment, and the reliability and safety of connecting parts are guaranteed; and the surface hardness and fatigue strength are enhanced through rolling treatment, the service life is prolonged, and the maintenance cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical parts manufacturing, in particular to a bolt manufacturing method. Background Art

[0002] With the rapid development of high-speed rail, new energy vehicles, engineering machinery, aerospace and other industries, the demand for high-strength, high-wear-resistant high-temperature alloy bolts has exploded. The connection of key components in these fields requires high-performance bolts to ensure the safe and stable operation of the system, and places extremely stringent requirements on the tensile strength, hardness, high-temperature durability and fatigue performance of the bolts.

[0003] In the field of high-performance high-temperature alloy bolt manufacturing, traditional hot forming and cold forming processes have significant defects. During the hot forming process, due to the lack of precise temperature control means, the forming temperature fluctuates greatly, often causing problems such as thread folding and oxidation decarburization, which seriously affects the mechanical properties and surface quality of the bolts, resulting in poor product stability and difficulty in meeting high-end application requirements. During cold forming, the material is prone to plastic damage under large deformation stress, and surface cracking occurs frequently, greatly reducing the product qualification rate and reliability. Summary of the invention

[0004] The purpose of the present invention is to provide a bolt manufacturing method, which avoids the defects of traditional hot and cold forming through warm upsetting processing, improves material utilization and product stability; grinding and thread rolling ensure dimensional accuracy and surface quality; solid solution and aging treatment improve various properties and ensure the reliability and safety of connecting parts; rolling treatment enhances surface hardness and fatigue strength, prolongs service life and reduces maintenance costs.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows: The present invention provides a method for manufacturing a bolt, comprising the following steps: S1. Forming a preset type of alloy material into a bolt blank by warm forging; S2, grinding and thread rolling the bolt blank to make a bolt; S3, performing a solution treatment on the bolt blank; S4, performing aging treatment on the bolt blank; S5, rolling the bolt blank to make a bolt.

[0006] Specifically, in this embodiment, in step S1, the working temperature of the warm upsetting process is 450-550°C.

[0007] Specifically, in this embodiment, the following steps are also included: S3a, after step S2 and before step S3, cleaning the bolt blank.

[0008] Specifically, in this embodiment, in the step S3, the treatment temperature of the solution treatment is 950-1000° C., and the time is 1-2 hours.

[0009] Specifically, in the present embodiment, in the step S4, the aging treatment includes an initial heat preservation, the temperature of the initial heat preservation is 700-730° C., and the time is 8-12 hours.

[0010] Specifically, in the present embodiment, in the step S4, the aging treatment further includes secondary heat preservation, the temperature of the secondary heat preservation is 600-630° C., and the time is 8-12 hours.

[0011] Specifically, in this embodiment, the following steps are also included: S4a, after step S4 and before step S5, cooling the bolt blank to room temperature.

[0012] Specifically, in this embodiment, the following steps are also included: S6. Perform magnetic particle inspection on the bolts.

[0013] Specifically, in this embodiment, the following steps are also included: S7. After step S6, surface treatment is performed on the bolt to increase the hardness of the bolt.

[0014] Specifically, in this embodiment, in the step S6, the bolts after the surface treatment are also tested, and the test includes a mechanical property test and a dimensional accuracy test.

[0015] The present invention provides a bolt manufacturing method, comprising: S1, forming a preset type of alloy material into a bolt blank by warm upsetting; S2, grinding and thread rolling the bolt blank to make a bolt; S3, performing solid solution treatment on the bolt blank; S4, performing aging treatment on the bolt blank; S5, performing rolling treatment on the bolt blank to make a bolt. Warm upsetting avoids the defects of traditional hot and cold forming, improves material utilization and product stability; grinding and thread rolling ensure dimensional accuracy and surface quality; solid solution and aging treatment improve various properties, ensure the reliability and safety of connecting parts; rolling treatment enhances surface hardness and fatigue strength, prolongs service life, and reduces maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 A processing flow chart of a bolt manufacturing method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the description of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "install", "connection" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0019] The directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front”, “back”, “top”, “bottom”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships commonly placed when the invention is used. They are only for the convenience of description and simplified description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as a limitation on the invention.

[0020] The terms "first", "second", "third" and the like are merely used to distinguish elements of similar nature, and do not indicate or imply relative importance or a particular order.

[0021] The terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion of the elements listed and may also include additional elements not expressly listed.

[0022] A preferred embodiment of the present invention provides a method for manufacturing a bolt, the flow chart of which is as follows: Figure 1 As shown, the bolt manufacturing method may include the following steps: S1. Forming a preset type of alloy material into a bolt blank by warm forging; S2, grinding and threading the bolt blank to make a bolt; S3, performing solid solution treatment on the bolt blank; S4. Perform aging treatment on the bolt blank; S5. Roll the bolt blank to make a bolt.

[0023] In this implementation, step S1 may include the following specific operations: First, raw materials are prepared, that is, the preset type of alloy material is selected. In this embodiment, a high-temperature alloy GH4169 round fine wire that meets specific quality standards can be selected as the alloy material, and then the required quality inspection is performed on it, including chemical composition analysis, mechanical property testing, appearance inspection, and dimensional accuracy measurement, etc., to ensure that the quality of the raw materials is reliable and meets the subsequent processing requirements.

[0024] Then, a warm upsetting die is designed and prepared according to the shape of the selected alloy material. In this embodiment, the dimension design of the warm upsetting bolt die gives priority to deformation characteristics such as the upsetting ratio S and the bundle ratio ε. The upsetting ratio S, i.e., the ratio of the length and diameter of the upsetting part of the processed blank, can be converted into the length dimension of the bolt head material according to the volume V of the bolt head by equal volume conversion; the bundle ratio ε, i.e., the ratio of the difference between the total cross-sectional area (Ft) of the raw material wire diameter before deformation and the cross-sectional area (F0) of the rod after deformation to the total cross-sectional area (Ft) of the raw material wire diameter before deformation; the required diameter specification of the raw material disc round material is obtained by calculation. In this embodiment, the cavity size is designed according to the size of the alloy material, and is preferably 0.03-0.06mm larger than the size of the alloy material.

[0025] Specifically, the upsetting ratio S is used to determine the length dimension of the bolt head material. By accurately calculating the ratio of the length and diameter of the upsetting part of the processed blank and combining it with the bolt head volume V for isovolumetric conversion, it can ensure that the raw material is reasonably distributed to the bolt head during the warm upsetting process, making the head forming more accurate and stable. It helps to ensure the dimensional accuracy and shape accuracy of the bolt head and avoid head defects caused by too much or too little material; the beam ratio ε reflects the change in the cross-sectional area of ​​the raw material before and after deformation. By calculating the difference between the total cross-sectional area of ​​the raw material wire diameter before deformation (Ft) and the cross-sectional area of ​​the rod after deformation (F0) and the ratio of Ft, the flow law and distribution of the material during the deformation process can be accurately grasped.

[0026] Then, the high-temperature alloy GH4169 round fine wire is placed in a warm forging device at a temperature of 450℃~550℃, and warm forging is performed at a processing speed of 120-160pcs / min to form a bolt blank.

[0027] The temperature range of the traditional hot forming process in the prior art is 800°C to 1000°C, and the temperature fluctuates greatly, which can easily lead to problems such as thread folding and oxidation decarburization, affecting the mechanical properties and surface quality of the bolts.

[0028] The temperature range of the warm upsetting process in the present application is 450°C to 550°C, which belongs to the low temperature warm upsetting range (lower than the recrystallization temperature), avoiding the problems of grain coarsening and recrystallization at high temperatures.

[0029] Beneficial effects: 1. Low-temperature warm upsetting improves the plastic deformation ability of the alloy, reduces deformation resistance, and reduces the risk of cracking during processing; 2. The temperature is controlled below 550°C to avoid recrystallization and grain coarsening, maintain the fine-grained structure of the alloy, and thus improve the mechanical properties.

[0030] In this implementation, step S2 may include the following specific operations: First, the workpiece after warm upsetting is ground. In this embodiment, by selecting a suitable grinding wheel and accurately setting the grinding process parameters, such as grinding speed, feed rate and grinding depth, it is ensured that the workpiece rod diameter after grinding reaches the design size and surface roughness requirements; then a specially designed and manufactured thread rolling die is used to perform the thread rolling operation, so that the bolt thread is formed in one time, ensuring the forming quality of the thread.

[0031] In this implementation, step S3 may include the following specific operations: Place the thread-rolled bolts in a heating furnace at 950-1000°C for 15-30 minutes, preferably 20 minutes, and then cool quickly to ensure the treatment effect. This allows various trace elements in the alloy material to fully dissolve in the matrix to form a uniform solid solution, eliminate the structural inhomogeneity generated during the processing, and improve the strength and toughness of the bolts.

[0032] In the prior art, the solution treatment temperature ranges from 920°C to 950°C, the holding time is 1 to 1.5 hours, and the cooling method is air cooling, while the solution treatment temperature in this application is 950°C-1000°C, the holding time is 20 minutes, and the cooling method is air cooling. The solution treatment temperature in this application is higher and the holding time is shorter.

[0033] Beneficial effects: 1. Higher solution treatment temperature can more fully dissolve the strengthening phases (such as γ'' phase and γ' phase) in the alloy, providing a uniform matrix structure for subsequent aging treatment. 2. Shorter holding time reduces energy consumption, and the solid solution structure is quickly fixed by air cooling to avoid premature precipitation of the strengthening phase, thereby improving the strength and corrosion resistance of the alloy.

[0034] In other embodiments, the method may further include step S3a, which is inserted after step S2 and before step S3: first, the bolts are cleaned after thread rolling to remove the coating and impurities generated on the surface of the product during the previous processing process to ensure the cleanliness of the product surface; then, the cleaned alloy material is subjected to solid solution treatment.

[0035] In this implementation, step S4 may include the following specific operations: The bolt blank after solution treatment is first heated to 700-730℃ and kept warm for 8-12 hours. In this temperature range, alloy elements begin to precipitate in the supersaturated solid solution to form fine dispersed phases. These dispersed phases can effectively hinder dislocation movement, thereby improving the strength and hardness of the bolt. Then it is cooled to 600-630℃ and kept warm for 8-12 hours, which promotes the uniform distribution and stable growth of the precipitated phase.

[0036] In the prior art, the aging treatment temperature ranges from 700°C to 730°C, the holding time is 6 to 8 hours, and the cooling method is air cooling. However, the aging treatment of this application adopts a two-stage holding method, which is 700-730°C holding for 8-12 hours and 600-630°C holding for another 8-12 hours, and the cooling method is air cooling.

[0037] Beneficial effects: 1. Higher aging temperature and longer holding time can promote more uniform precipitation of strengthening phases (such as γ'' phase and γ' phase), thereby improving the strength and high-temperature properties of the alloy. 2. Two-stage aging treatment optimizes the structural stability of the alloy, giving it better creep resistance and fatigue performance in high-temperature environments.

[0038] In other embodiments, the method may further include step S4a, which is inserted after step S4 and before step S5: cooling the alloy material to 600-630°C in the furnace and then keeping it warm for 8-12 hours, and then air-cooling it to room temperature to further improve the strength, hardness and high temperature durability of the bolt.

[0039] In this implementation, step S5 may include the following specific operations: The bolt blank is subjected to rolling treatment, specifically, the fillet under the bolt head is strengthened so that the fillet under the head obtains appropriate cold work hardening effect, improves the fatigue strength of the bolt, and manufactures the bolt.

[0040] In other embodiments, the method may further include step S6, which is inserted after step S5: using magnetic particle inspection to inspect the surface and near-surface defects of the manufactured bolts, screening out unqualified products with defects such as cracks and inclusions, ensuring that the quality of the bolts put into use meets the requirements and ensuring safe use.

[0041] In other embodiments, the method may further include step S7, which is inserted after step S6: performing corresponding surface treatment on the bolts after the flaw detection inspection to enhance the corrosion resistance and wear resistance of the bolts, improve the appearance quality, and increase the service life and applicability of the bolts in different environments.

[0042] Finally, after step S7, the bolts after surface treatment can also be tested for various indicators such as tensile strength, hardness, and dimensional accuracy using existing technical means to ensure that the products meet the design standards and quality requirements. Only qualified products can enter the packaging and warehousing stage to ensure the high quality of the final product.

[0043] In the bolt manufacturing method provided by the present invention, the defects of traditional hot and cold forming are avoided through warm upsetting processing, thereby improving material utilization and product stability; grinding and thread rolling ensure dimensional accuracy and surface quality; solid solution and aging treatment improve various properties and ensure the reliability and safety of connecting parts; rolling treatment enhances surface hardness and fatigue strength, prolongs service life, and reduces maintenance costs.

[0044] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for manufacturing a bolt, characterized in that: The following steps are involved: S1. Forming a preset type of alloy material into a bolt blank by warm forging; S2, grinding and thread rolling the bolt blank to make a bolt; S3, performing a solution treatment on the bolt blank; S4, performing aging treatment on the bolt blank; S5, rolling the bolt blank to make a bolt.

2. The bolt manufacturing method according to claim 1, characterized in that: In step S1, the working temperature of the warm upsetting process is 450-550°C.

3. The bolt manufacturing method according to claim 1, characterized in that: The following steps are also included: S3a, after step S2 and before step S3, cleaning the bolt blank.

4. The bolt manufacturing method according to claim 1, characterized in that: In the step S3, the treatment temperature of the solution treatment is 950-1000° C. and the time is 15-30 minutes.

5. The bolt manufacturing method according to claim 1, characterized in that: In the step S4, the aging treatment includes an initial heat preservation, the temperature of the initial heat preservation is 700-730° C., and the time is 8-12 hours.

6. The bolt manufacturing method according to claim 5, characterized in that: In the step S4, the aging treatment further includes secondary heat preservation, the temperature of the secondary heat preservation is 600-630° C., and the time is 8-12 hours.

7. The bolt manufacturing method according to claim 6, characterized in that: The following steps are also included: S4a, after step S4 and before step S5, cooling the bolt blank to room temperature.

8. The bolt manufacturing method according to claim 1, characterized in that: The following steps are also included: S6. Perform magnetic particle inspection on the bolts.

9. The bolt manufacturing method according to claim 8, characterized in that: The following steps are also included: S7. After step S6, surface treatment is performed on the bolt to increase the hardness of the bolt.

10. The bolt manufacturing method according to claim 9, characterized in that: In the step S6, the bolts after the surface treatment are tested, and the testing includes mechanical property testing and dimensional accuracy testing.

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