CN112226588B - Bolt machining process - Google Patents
Bolt machining process Download PDFInfo
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- CN112226588B CN112226588B CN202010953629.3A CN202010953629A CN112226588B CN 112226588 B CN112226588 B CN 112226588B CN 202010953629 A CN202010953629 A CN 202010953629A CN 112226588 B CN112226588 B CN 112226588B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/32—Soft annealing, e.g. spheroidising
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K1/00—Making machine elements
- B21K1/44—Making machine elements bolts, studs, or the like
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/34—Methods of heating
- C21D1/42—Induction heating
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or vacuum
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0093—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for screws; for bolts
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/18—Pretreatment of the material to be coated
- C23C18/1803—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces
- C23C18/1824—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment
- C23C18/1827—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment only one step pretreatment
- C23C18/1834—Use of organic or inorganic compounds other than metals, e.g. activation, sensitisation with polymers
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/38—Coating with copper
- C23C18/40—Coating with copper using reducing agents
- C23C18/405—Formaldehyde
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
- C23C28/023—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/38—Electroplating: Baths therefor from solutions of copper
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/003—Threaded pieces, e.g. bolts or nuts
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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- Y02P10/25—Process efficiency
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Abstract
The application relates to a bolt machining process, relates to the technical field of fastener machining, and comprises the following steps: s1: induction heating the rolled steel to 395-405 ℃ at the frequency of 1000-5000 Hz, preserving heat for 5-7 s, and then performing warm heading forming at the temperature of 398-402 ℃ to obtain a bolt blank; s2: the bolt blank is subjected to thread rolling, flat-end chamfering, sand blasting, tempering and copper plating to obtain the bolt.
Description
Technical Field
The application relates to the technical field of fastener processing, in particular to a bolt processing technology.
Background
The fastener is used for fastening connection and is widely applied to mechanical parts in various fields of machinery, electricity, automobiles, transportation, aerospace and the like. The bolt is a cylindrical threaded fastener matched with a nut, consists of a head part and a screw rod, and plays a role in fastening and connecting two parts with through holes by matching with the nut. With the development of economy, the manufacturing standard of the fasteners such as bolts and the like is gradually in track with the national standard, which puts higher requirements on the manufacturing of the fasteners such as bolts and the like.
At present, fasteners such as bolts and the like are generally formed by a cold heading process or a hot heading process, and metal materials are easy to expand by heating at a higher temperature; and when the metal material is formed at normal temperature, the metal material can generate larger resistance when being subjected to plastic deformation, so that the specification of the formed bolt is different from the required specification by adopting a cold heading process or a hot heading process. Therefore, in order to improve the precision of the bolt, the formed bolt needs to be turned and then subjected to subsequent processing, the introduction of the turning process makes the processing technology of the bolt complicated, the waste of raw materials is more, and the production cost of the bolt is improved.
Disclosure of Invention
In order to simplify the processing steps of the bolt and reduce the production cost of the bolt, the application provides a processing technology of the bolt.
The application provides a bolt machining process, which adopts the following technical scheme:
a bolt machining process comprises the following steps:
s1: induction heating the rolled steel to 395-405 ℃ at the frequency of 1000-5000 Hz, preserving heat for 5-7 s, and then performing warm heading forming at the temperature of 398-402 ℃ to obtain a bolt blank;
s2: and (3) carrying out thread rolling, flat-end chamfering, sand blasting, tempering and copper plating on the bolt blank to obtain the bolt.
Preferably, in step S1, the coiled steel material is first heat-preserved at 395-399 ℃ for 1-2S, then heat-preserved at 400 ℃ for 2S, and then heat-preserved at 401-405 ℃ for 2-3S.
Preferably, in step S1, the temperature of the warm heading forming is 400 ℃.
Preferably, the type of the coiled steel material is 40Cr10Si2 Mo.
By adopting the technical scheme, the 40Cr10Si2Mo coiled steel material is used as the raw material of the bolt, and the 40Cr10Si2Mo has high heat resistance and high strength, so that the manufactured bolt has high tensile strength and yield strength.
This application is with coil stock steel earlier through intermediate frequency electromagnetic induction heating to specific temperature range to set up specific temperature gradient scope in this specific temperature range, can make the surface of coil stock steel heat rapidly and rise to higher temperature, heating efficiency is higher, can not make coil stock steel be in under the higher temperature for a long time, has reduced the possibility that oxidation appears in coil stock steel surface, has improved the quality of the bolt that makes. And then sending the coil steel subjected to induction heating into an upsetter, and carrying out a warm-upsetting forming process on the coil steel under a specific temperature condition, so that the bolt blank prepared after the warm-upsetting forming is stable in size, extremely low in volume change rate, high in tensile strength and yield strength, and capable of directly carrying out subsequent processing processes such as thread rolling and the like on the bolt blank after the warm-upsetting forming, the size of the bolt blank does not need to be further adjusted through machining and turning, the technological process of bolt processing is simplified, and the production cost is greatly reduced.
Meanwhile, new stress can be generated inside the bolt again due to the introduction of the machining turning process, and the strength and the dimensional stability of the bolt are reduced, so that the size specification of the bolt blank after warm heading forming can meet the subsequent processing requirement, the processing technology is simplified, and the tensile strength and the yield strength of the manufactured bolt are improved.
The bolt blank after warm heading forming is subjected to thread rolling, so that a thread structure is arranged on the bolt blank, then flat-head chamfering and sand blasting processes are carried out on the bolt blank, the head of the bolt blank is provided with a hexagonal structure, and the bolt blank is integrally polished to be smooth. And finally, carrying out a copper plating process to repair the worn part on the bolt blank, reducing the possibility of local carburization and improving the corrosion resistance of the bolt.
Preferably, before the step S1, the isothermal spheroidizing annealing process is performed on the coil stock steel material by using the following method:
the coiled steel is firstly kept at 795-805 ℃ for 1-2 h, then cooled to 690-705 ℃, kept at the temperature for 47-48 h, then cooled to 598-602 ℃ at the speed of 0.67-0.75 ℃/min, taken out of the furnace, and naturally cooled to room temperature.
Preferably, in the step S1, the hardness of the steel material for the coil stock is 118 to 122 HV.
Preferably, in the step S1, the hardness of the steel material for wire stock used is 120 HV.
By adopting the technical scheme, before the coiled steel is subjected to induction heating, the isothermal spheroidizing annealing process is firstly carried out on the coiled steel according to the process method, and each process parameter of the isothermal spheroidizing annealing process is strictly controlled within a specific range, so that the spheroidizing structure of the coiled steel is uniform, the surface is phosphorized, meanwhile, the hardness of the annealed coiled steel can be strictly controlled within a specific range, and the specific hardness value is further controlled, so that the coiled steel subjected to the induction heating process has higher hardness, and the hardness of the manufactured bolt is improved.
Preferably, in step S2, the bolt blank is hardened and tempered by the following method:
heating to 878-882 ℃ at the pressure of 1.5 x 10 < -2 > Pa-2.5 x 10 < -2 > Pa at the speed of 4.97-5.03 ℃/min, preserving the heat for 235-245 min, filling high-purity argon to increase the system pressure to 0.13-0.17 MPa, cooling to 63-67 ℃ at the speed of 4.95-5.05 ℃/min, and discharging to obtain the tempered bolt blank.
By adopting the technical scheme, the bolt blank is subjected to vacuum quenching for quenching and tempering under the vacuum degree in a specific range, then high-purity inert gas is introduced for quenching and tempering continuously, the metallographic structure inside the bolt blank is adjusted, some tissue defects generated in the warm heading forming process are eliminated, the uniformity of the metallographic structure is enhanced, the stress of the bolt blank is eliminated, the strength and the hardness of the bolt blank are greatly improved, and the impact toughness of the bolt blank is improved.
Preferably, in step S2, the bolt blank is copper-plated by the following method:
the bolt blank is cleaned in an alkaline mode at the temperature of 20-25 ℃, then copper plating liquid is adopted to plate copper on the surface of the bolt blank in a thickness of 0.5-1.0 mu m at the deposition speed of 1.2-2.4 mu m/h, and then electroplating is carried out, so that the thickness of the plated copper is 5-8 mu m.
By adopting the technical scheme, because the surface condition of the bolt blank can generate important influence on the quality of the chemical copper plating, the bolt blank is firstly cleaned in an alkaline way to remove attachments such as oil stain, dust and the like on the surface of the bolt blank, the effect of the chemical copper plating is improved, then the chemical copper plating process is carried out on the surface of the bolt blank according to the deposition speed in a specific range, the thickness of the chemical copper plating is controlled in the specific range, the chemical copper plating is thickened by using electroplating assistance, the surface copper plating thickness of the bolt blank is finally in the specific range, the binding force of the copper plating layer and the surface of the bolt blank is enhanced, the copper plating layer can be continuously coated on the surface of the bolt blank, the worn part of the bolt blank is repaired, the possibility of local carburization is reduced, the corrosion resistance of the bolt is improved, and no bubble is formed on the surface of the copper plating layer, Has no crack. The copper plating layer is too low or too high in thickness, the copper plating quality and effect of the bolt blank can be affected, the corrosion resistance of the bolt can be reduced due to the fact that the copper plating layer is low in thickness, the copper plating layer is too high, the phenomenon that the binding force with the bolt blank is poor, the surface is foamed, the bolt blank is cracked and the like can occur, and the resistivity of the bolt blank is affected.
Preferably, the copper plating solution comprises the following components in mass concentration: 1.5-2.5 g/L copper sulfate, 1.0-3.0 g/L copper chloride, 3.0-4.0 g/L formaldehyde, 0.15-0.3 g/L potassium sodium tartrate, 1.2-1.5 g/L citric acid, 0.6-0.8 g/L polyvinyl alcohol, 0.8-1.2 g/L lauryl alcohol, 0.5-0.8 g/L lithium hydroxide and 0.1-0.2 g/L sulfuric acid.
By adopting the technical scheme, the copper sulfate and the copper chloride with specific mass concentration ranges are selected as the main salts to provide the Cu with specific mass concentration2+If it is Cu2+Too high a mass concentration of (b) may significantly decrease the stability of the copper plating solution, if Cu2+The mass concentration of the copper plating solution is too low, so that the deposition speed of the copper plating solution on the surface of the bolt blank is slow, and the copper plating layer is dark.
According to the method, formaldehyde with specific mass concentration is used as a reducing agent, the deposition speed of the copper plating solution on the surface of the bolt blank can be increased, the quality and the effect of a copper plating layer are improved, but the formaldehyde has certain irritation, so that the mass concentration of the formaldehyde must be controlled within the range.
Because the copper plating solution is used for copper plating in an alkaline environment, the potassium sodium tartrate in a specific concentration range is matched with the citric acid for use, so that the potassium sodium tartrate is matched with the Cu2+Produces stable complex, can improve the stability of the copper plating solution, and can play a role in thinning the plated product particles.
Meanwhile, the polyvinyl alcohol and the lauryl alcohol in a specific mass concentration range are mixed and matched for use, so that the surface tension of the copper plating solution can be reduced, hydrogen generated in the chemical copper plating process is easy to separate from the surface of a precipitated copper layer, and the possibility of hydrogen embrittlement is reduced.
According to the method, lithium hydroxide and sulfuric acid with specific mass concentration ranges are added into the copper plating solution, the pH value of the copper plating solution is adjusted within a proper range, the stability of the deposition speed of the copper plating solution on the surface of a bolt blank is improved, the thickness of a copper plating layer can be strictly controlled within a specific range, and therefore the quality and the effect of copper plating are improved.
In conclusion, the components in a specific mass concentration range are selected and mixed for use as the copper plating solution in the copper plating process of the bolt blank, so that the copper plating solution has high stability, the internal stress of the copper plating layer can be eliminated, the copper plating effect of the bolt blank is improved, and the toughness of the copper plating layer is improved.
In summary, the present application includes at least one of the following beneficial technical effects:
1. according to the bolt machining process, the processes of isothermal spheroidizing annealing, induction heating, warm upsetting forming and the like are adopted, so that the formed bolt is stable in size, small in volume change rate and high in strength and hardness;
2. according to the bolt machining process, after warm heading forming, a machining turning process is not needed, so that the process steps are greatly simplified, and the production cost is obviously reduced;
3. according to the bolt machining process, the quenching and tempering process is carried out by adopting vacuum quenching, so that the uniformity of the metallographic structure of the bolt is enhanced, and the impact toughness of a blank of the bolt is improved.
Detailed Description
The present application will be described in further detail with reference to examples.
In the following examples and comparative examples:
the coil steel material 40Cr10Si2Mo was obtained from Shanghai Yu Steel industries, Inc.
Example 1
A bolt machining process comprises the following steps:
s0: isothermal spheroidizing annealing process: firstly, keeping the temperature of the steel plate material 40Cr10Si2Mo at 795 ℃ for 1h, then cooling to 690 ℃, keeping the temperature for 47h, then cooling to 598 ℃ at the speed of 0.67 ℃/min, discharging, and naturally cooling to room temperature;
s1: induction heating the steel material coil 40Cr10Si2Mo to 395 ℃ at the frequency of 1000Hz, preserving heat for 1s, heating to 400 ℃ and preserving heat for 2s, then heating to 401 ℃, preserving heat for 2s, and then sending the steel material coil to an upsetting machine for medium-temperature upsetting and forming at the temperature of 398 ℃ to obtain a bolt blank;
s2: carrying out thread rolling, flat-end chamfering, sand blasting, tempering and copper plating on the bolt blank to obtain a bolt;
wherein in step S1, the hardness of the steel material of the coil stock 40Cr10Si2Mo is 118 HV;
in step S2, the bolt blank is quenched and tempered by the following method:
at 1.5X 10-2Heating to 878 ℃ at the speed of 4.97 ℃/min under the pressure of Pa, preserving heat for 235min, filling high-purity argon to increase the system pressure to 0.13MPa, cooling to 63 ℃ at the speed of 4.95 ℃/min, discharging, and obtaining a tempered bolt blank;
in step S2, the bolt blank is plated with copper by the following method:
alkaline cleaning the quenched and tempered bolt blank at the temperature of 20 ℃, then chemically plating copper on the surface of the bolt blank by the copper plating solution at the deposition speed of 1.2 mu m/h for 0.5 mu m, and then electroplating to ensure that the thickness of the plated copper is 5 mu m; the copper plating solution comprises the following components in mass concentration: 1.5g/L copper sulfate, 3.0g/L copper chloride, 3.0g/L formaldehyde, 0.3g/L potassium sodium tartrate, 1.2g/L citric acid, 0.8g/L polyvinyl alcohol, 0.8g/L lauryl alcohol, 0.8g/L lithium hydroxide and 0.1g/L sulfuric acid.
Example 2
A bolt machining process comprises the following steps:
s0: isothermal spheroidizing annealing process: firstly, preserving heat for 1.5h at 800 ℃ of the steel plate material 40Cr10Si2Mo, then cooling to 697.5 ℃, preserving heat for 47.5h, then cooling to 600 ℃ at the speed of 0.71 ℃/min, discharging, and naturally cooling to room temperature;
s1: induction heating the coiled steel material 40Cr10Si2Mo to 397 ℃ at the frequency of 3000Hz, preserving heat for 1.5s, heating to 400 ℃ for 2s, then heating to 403 ℃ and preserving heat for 2.5s, and then sending the coiled steel material into an upsetting machine for medium-temperature upsetting and forming at the temperature of 400 ℃ to obtain a bolt blank;
s2: carrying out thread rolling, flat-end chamfering, sand blasting, tempering and copper plating on the bolt blank to obtain a bolt;
wherein in step S1, the hardness of the steel material of the coil stock 40Cr10Si2Mo is 120 HV;
in step S2, the bolt blank is quenched and tempered by the following method:
at 2.0X 10-2Heating to 880 ℃ at the speed of 5.00 ℃/min under the pressure of Pa, preserving heat for 240min, filling high-purity argon to improve the system pressure to 0.15MPa, cooling to 65 ℃ at the speed of 5.00 ℃/min, discharging to obtain a tempered bolt blank;
in step S2, the bolt blank is plated with copper by the following method:
alkaline cleaning the quenched and tempered bolt blank at the temperature of 23 ℃, then chemically plating copper on the surface of the bolt blank by the copper plating solution at the deposition speed of 1.8 mu m/h for 0.75 mu m, and then electroplating to ensure that the copper plating thickness is 6.5 mu m; wherein the copper plating solution comprises the following components in mass concentration: 2.0g/L copper sulfate, 2.0g/L copper chloride, 3.5g/L formaldehyde, 0.225g/L potassium sodium tartrate, 1.35g/L citric acid, 0.7g/L polyvinyl alcohol, 1.0g/L lauryl alcohol, 0.65g/L lithium hydroxide and 0.15g/L sulfuric acid.
Example 3
A bolt machining process comprises the following steps:
s0: isothermal spheroidizing annealing process: firstly, preserving heat for 2h at the temperature of 805 ℃ for the steel plate material 40Cr10Si2Mo, then cooling to the temperature of 705 ℃, preserving heat for 48h, then cooling to the temperature of 602 ℃ at the speed of 0.75 ℃/min, discharging, and naturally cooling to the room temperature;
s1: induction heating the steel coil material 40Cr10Si2Mo to 399 ℃ at the frequency of 3000Hz, preserving heat for 2s, heating to 400 ℃ again, preserving heat for 2s, then heating to 405 ℃, preserving heat for 3s, and then sending the steel coil material to an upsetting machine for medium-temperature upsetting and forming at the temperature of 402 ℃ to obtain a bolt blank;
s2: carrying out thread rolling, flat-end chamfering, sand blasting, tempering and copper plating on the bolt blank to obtain a bolt;
wherein, in step S1, the hardness of the steel material of the coil stock 40Cr10Si2Mo is 122 HV;
in step S2, the bolt blank is quenched and tempered by the following method:
at 2.5X 10-2Heating to 882 ℃ at a speed of 5.03 ℃/min under Pa, preserving heat for 245min, filling high-purity argon to increase the system pressure to 0.17MPa, cooling to 67 ℃ at a speed of 5.05 ℃/min, discharging, and obtaining a tempered bolt blank;
in step S2, the bolt blank is plated with copper by the following method:
alkaline cleaning the quenched and tempered bolt blank at 25 ℃, then chemically plating copper on the surface of the bolt blank by 1.0 mu m at the deposition speed of 2.4 mu m/h by using a copper plating solution, and then electroplating to ensure that the thickness of the plated copper is 8 mu m; wherein the copper plating solution comprises the following components in mass concentration: 2.5g/L copper sulfate, 1.0g/L copper chloride, 4.0g/L formaldehyde, 0.15g/L potassium sodium tartrate, 1.5g/L citric acid, 0.6g/L polyvinyl alcohol, 1.2g/L lauryl alcohol, 0.5g/L lithium hydroxide and 0.2g/L sulfuric acid.
Comparative example 1
The processing technology of the common bolt comprises the following steps:
a: molding:
sending the coiled steel material 40Cr10Si2Mo into an upsetting machine for hot upsetting forming at the temperature of 1000 ℃, and then naturally cooling to room temperature to obtain a bolt blank;
b: machining:
turning the bolt blank to obtain a bolt blank with accurate specification;
c: and (3) heat treatment:
c 1: preheating the bolt blank in a preheating furnace at 700 ℃ for 5h, and then keeping the temperature in a salt bath furnace at 720 ℃ for 4h for quenching;
c 2: tempering the bolt blank quenched in b1 at 220 ℃, then preserving heat for 5 hours, and naturally cooling to room temperature;
d: fine processing:
and c, performing thread rolling, flat head chamfering and copper plating on the bolt blank subjected to the heat treatment in the step b to obtain the bolt.
Comparative example 2
The processing technology of the common bolt comprises the following steps:
i: molding:
sending the coiled steel material 40Cr10Si2Mo into an upsetting machine for cold upsetting forming at the temperature of 25 ℃ to obtain a bolt blank;
II: machining:
turning the bolt blank to obtain a bolt blank with accurate specification;
III: fine processing:
and (4) carrying out thread rolling, flat-end chamfering and copper plating on the bolt blank with accurate specification to obtain the bolt.
Performance detection
The dimensional stability, strength and hardness of the bolt blank obtained by the forming steps of examples 1 to 3 and comparative examples 1 to 2 were tested as shown in table 1, and then the copper plating effect, strength, impact toughness and hardness of the bolts obtained by the forming steps of examples 1 to 3 and comparative examples 1 to 2 were tested as shown in table 2:
1. and (3) copper plating effect test: the bolts prepared in the examples 1-3 and the comparative examples 1-2 are subjected to heat preservation at the temperature of 50 ℃ for 1 hour, then taken out and cooled at room temperature for 15 minutes, then subjected to heat preservation at the temperature of-40 ℃ for 1 hour, taken out and then kept stand at room temperature for 15 minutes, the above process is 1 cycle, and the copper plating condition of the bolt surface is observed after the bolt is subjected to four continuous cycle periods.
2. And (3) testing the dimensional stability: the diameter of the coiled steel material in the embodiments 1-3 and the comparative examples 1-2 before the forming step is measured by a micrometer, the diameter of the screw of the bolt in the embodiments 1-3 and the comparative examples 1-2 after the forming step is measured by the micrometer, the change rate (%) of the size is calculated, and the average value is obtained after three times of measurement.
3. And (3) testing the strength performance: reference GB/T228.1-2010 section 1 of the tensile test of metallic materials: the room temperature test method detects the tensile strength (Mpa) and the yield strength (Mpa) of the bolt blank after the molding step and the finally prepared bolt respectively.
4. And (3) testing hardness performance: reference is made to GB/T4340.1-2009 section 1 of Vickers hardness test of Metal materials: test methods vickers Hardness (HV) was measured under 980.7N test force for each of the bolt blank after the molding step and the finally obtained bolt.
5. And (3) impact toughness testing: reference BG/T229-3）。
Table 1 table of detection results of molded bolt blank
| Item | Dimensional Change Rate (%) | Tensile strength (Mpa) | Yield strength (Mpa) | Vickers Hardness (HV) |
| Example 1 | 0.005 | 988 | 927 | 240 |
| Example 2 | 0.003 | 992 | 934 | 250 |
| Example 3 | 0.006 | 990 | 922 | 240 |
| Comparative example 1 | 0.75 | 798 | 740 | 150 |
| Comparative example 2 | 0.68 | 785 | 732 | 130 |
As can be seen from Table 1, the dimension change rate of the bolt blank obtained by performing warm heading forming on the coiled steel material in the embodiments 1-3 is 0.03-0.06%, the tensile strength is 988-992 MPa, the yield strength is 922-927 MPa, and the Vickers hardness under the test force of 980.7N is kept between 240-250 NV. Experimental results show that the size change rate of the bolt blank formed by warm heading in the embodiment 1-3 is low, the size is stable, the strength and the hardness are high, the subsequent technological process can be directly carried out, the size does not need to be adjusted by turning, the production process is simplified, and the production cost is reduced.
Compared with the examples 1-3, the comparative examples 1-2 have the size change rate obviously higher than that of the examples 1-3, the tensile strength, the yield strength and the Vickers hardness obviously lower than that of the examples 1-3, and the fact that the size change rate of the bolt blank obtained by the hot heading forming method and the cold heading forming method is higher is shown, so that the turning process, the size adjustment and the subsequent processing process need to be carried out continuously, the process is complicated, and the cost is higher.
TABLE 2 bolt test results table
| Item | Tensile strength (Mpa) | Yield strength (Mpa) | Vickers Hardness (HV) | Impact toughness (J/cm)3） | Copper plating effect |
| Example 1 | 1260 | 1215 | 435 | 57.3 | Without cracks |
| Example 2 | 1265 | 1220 | 440 | 58.9 | Without cracks |
| Example 3 | 1261 | 1217 | 436 | 57.9 | Without cracks |
| Comparative example 1 | 835 | 849 | 365 | 41.2 | Peeling |
| Comparative example 2 | 829 | 843 | 325 | 40.8 | Peeling |
As can be seen from Table 2, the tensile strength of the bolts prepared by the methods in examples 1 to 3 is 1260 to 1265Mpa, the yield strength is 1215 to 1220Mpa, the Vickers hardness under 980.7N test force is kept between 435 and 440NV, and the impact toughness is 57.3 to 58.9J/cm3In the meantime. Experimental results show that the bolt prepared by the method in the embodiment 1-3 has high tensile strength, yield strength, Vickers hardness and impact toughness, and is good in copper plating effect and free of cracks, bubbles, peeling and the like on the surface.
Compared with the examples 1 to 3, the tensile strength, the yield strength and the Vickers hardness of the comparative examples 1 to 2 are obviously lower than those of the examples 1 to 3, which shows that the machining process is complicated and the strength, the hardness and the impact toughness of the bolt are reduced by adopting the turning process.
The embodiments of the present invention are preferred embodiments of the present application, and the scope of protection of the present application is not limited by the embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.
Claims (8)
1. The machining process of the bolt is characterized by comprising the following steps of:
s1: firstly, preserving heat of a coiled steel material for 1-2 hours at the temperature of 795-805 ℃, then cooling to the temperature of 690-705 ℃, preserving heat for 47-48 hours, then cooling to the temperature of 598-602 ℃ at the speed of 0.67-0.75 ℃/min, discharging, naturally cooling to room temperature, then inductively heating the coiled steel material to 395-405 ℃ at the frequency of 1000-5000 Hz, preserving heat for 5-7 s, and then performing warm heading forming at the temperature of 398-402 ℃ to obtain a bolt blank;
s2: carrying out thread rolling, flat-end chamfering, sand blasting, tempering and copper plating on the bolt blank to obtain a bolt;
the hardening and tempering process comprises the following specific steps:
at 1.5X 10-2Pa~2.5×10-2Heating to 878-882 ℃ at the speed of 4.97-5.03 ℃/min under the pressure of Pa, preserving heat for 235-245 min, filling high-purity argon to improve the system pressure to 0.13-0.17 MPa, cooling to 63-67 ℃ at the speed of 4.95-5.05 ℃/min, and discharging to obtain the tempered bolt blank.
2. The machining process of the bolt according to claim 1, wherein: in the step S1, the steel coil stock is firstly subjected to heat preservation for 1-2S at the temperature of 395-399 ℃, then is subjected to heat preservation for 2S at the temperature of 400 ℃, and is subjected to heat preservation for 2-3S at the temperature of 401-405 ℃.
3. The machining process of the bolt according to claim 1, wherein: in step S1, the temperature of the warm heading forming is 400 ℃.
4. The machining process of the bolt according to claim 1, wherein: the type of the coiled steel material is 40Cr10Si2 Mo.
5. The machining process of the bolt according to claim 1, wherein: in the step S1, the hardness of the steel material for the coil stock is 118-122 HV.
6. The machining process of the bolt according to claim 5, wherein the machining process comprises the following steps: in step S1, the hardness of the steel material for a wire rod used is 120 HV.
7. The machining process of the bolt according to claim 1, wherein: in step S2, the bolt blank is plated with copper by the following method:
the bolt blank is cleaned in an alkaline mode at the temperature of 20-25 ℃, then copper plating liquid is adopted to plate copper on the surface of the bolt blank in a thickness of 0.5-1.0 mu m at the deposition speed of 1.2-2.4 mu m/h, and then electroplating is carried out, so that the thickness of the plated copper is 5-8 mu m.
8. The process for machining a bolt according to claim 7, wherein: the copper plating solution comprises the following components in mass concentration: 1.5-2.5 g/L copper sulfate, 1.0-3.0 g/L copper chloride, 3.0-4.0 g/L formaldehyde, 0.15-0.3 g/L potassium sodium tartrate, 1.2-1.5 g/L citric acid, 0.6-0.8 g/L polyvinyl alcohol, 0.8-1.2 g/L lauryl alcohol, 0.5-0.8 g/L lithium hydroxide and 0.1-0.2 g/L sulfuric acid.
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| CN113500159A (en) * | 2021-07-07 | 2021-10-15 | 安徽长江紧固件有限责任公司 | Warm-heading composite forming process for high-strength fastener |
| CN113399950A (en) * | 2021-07-13 | 2021-09-17 | 安徽长江紧固件有限责任公司 | Production process of large-hexagon high-strength bolt with pre-loaded calibration stress |
| CN113843584A (en) * | 2021-09-01 | 2021-12-28 | 苏州施必牢精密紧固件有限公司 | Processing method of fastener not easy to brittle fracture in low-temperature environment |
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