CN111015101A - Processing method of high-fatigue-life and high-strength bolt - Google Patents
Processing method of high-fatigue-life and high-strength bolt Download PDFInfo
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- CN111015101A CN111015101A CN201911270718.1A CN201911270718A CN111015101A CN 111015101 A CN111015101 A CN 111015101A CN 201911270718 A CN201911270718 A CN 201911270718A CN 111015101 A CN111015101 A CN 111015101A
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- bolts
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- shot blasting
- life
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- 238000003672 processing method Methods 0.000 title claims abstract description 9
- 238000000034 method Methods 0.000 claims abstract description 48
- 229910000851 Alloy steel Inorganic materials 0.000 claims abstract description 16
- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
- 238000005422 blasting Methods 0.000 claims description 64
- 238000010438 heat treatment Methods 0.000 claims description 50
- 238000010791 quenching Methods 0.000 claims description 32
- 238000001816 cooling Methods 0.000 claims description 28
- 230000000171 quenching effect Effects 0.000 claims description 28
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 24
- 238000005496 tempering Methods 0.000 claims description 24
- 238000004140 cleaning Methods 0.000 claims description 16
- 238000000227 grinding Methods 0.000 claims description 16
- 238000005096 rolling process Methods 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 13
- 229910052757 nitrogen Inorganic materials 0.000 claims description 12
- 238000000137 annealing Methods 0.000 claims description 9
- 229910000831 Steel Inorganic materials 0.000 claims description 8
- 238000007689 inspection Methods 0.000 claims description 8
- 229920002635 polyurethane Polymers 0.000 claims description 8
- 239000004814 polyurethane Substances 0.000 claims description 8
- 230000002787 reinforcement Effects 0.000 claims description 8
- 239000010959 steel Substances 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 230000007547 defect Effects 0.000 claims description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 4
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 claims description 4
- 229940010552 ammonium molybdate Drugs 0.000 claims description 4
- 235000018660 ammonium molybdate Nutrition 0.000 claims description 4
- 239000011609 ammonium molybdate Substances 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 238000004320 controlled atmosphere Methods 0.000 claims description 4
- 238000005238 degreasing Methods 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 4
- 239000000428 dust Substances 0.000 claims description 4
- 238000000465 moulding Methods 0.000 claims description 4
- 238000004806 packaging method and process Methods 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims description 4
- 238000012216 screening Methods 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 4
- 238000005728 strengthening Methods 0.000 claims description 4
- 238000004381 surface treatment Methods 0.000 claims description 4
- 206010039509 Scab Diseases 0.000 claims description 3
- 238000005261 decarburization Methods 0.000 claims description 3
- 238000007373 indentation Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 238000009661 fatigue test Methods 0.000 abstract description 8
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003137 locomotive effect Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B33/00—Features common to bolt and nut
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B33/00—Features common to bolt and nut
- F16B33/06—Surface treatment of parts furnished with screw-thread, e.g. for preventing seizure or fretting
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
The invention discloses a method for processing a high-fatigue-life and high-strength bolt, which relates to the technical field of fastener manufacturing, in particular to a method for processing a high-fatigue-life and high-strength bolt, wherein 9 groups of different high-strength bolts are selected, and the method is specifically divided into the following 9 types: 8.8-grade alloy steel outer hexagon bolts; 10.9 grade alloy steel outer hexagon bolts; 12.9-grade alloy steel outer hexagon bolts; 8.8 grade cylindrical head screw; 10.9 grade cylindrical cap screw; 12.9 grade cylinder head screw; 8.8 grade flange face bolts; 10.9 grade flange face bolts; grade 12.9 flange face bolts. According to the processing method of the high-fatigue-life and high-strength bolt, when 20% of tensile strength is the maximum loading load of a fatigue test and the tensile fatigue life test with the stress ratio of 0.1 is carried out, the fatigue life of the 10.9-grade and 12.9-grade high-strength bolts is over 500 ten thousand times. When the tensile fatigue life test with the tensile strength of 46 percent as the maximum loading load of the fatigue test and the stress ratio of 0.1 is carried out, the fatigue life of the bolts of 10.9 grade and 12.9 grade of the invention is more than 20 ten thousand times.
Description
Technical Field
The invention relates to the technical field of fastener manufacturing, in particular to a method for processing a high-fatigue-life and high-strength bolt.
Background
The thread belongs to a multi-notch part, and when the tensile strength of 46 percent is the maximum loading load of a fatigue test and the tensile fatigue life test with the stress ratio of 0.1 is carried out, the fatigue life of a common high-strength bolt is only 5 ten thousand times. In the tensile fatigue life test in which 20% of the tensile strength is the maximum load of the fatigue test and the stress ratio is 0.1, the fatigue life of a common high-strength bolt is only 100 ten thousand times, and in the tensile fatigue life test in which 46% of the tensile strength is the maximum load of the fatigue test and the stress ratio is 0.1, the fatigue life of a 10.9-grade or 12.9-grade bolt is required to be more than 10 ten thousand times for a high-strength bolt used in a high-speed locomotive power system, an automobile power system and the like. When 20% of the tensile strength is the maximum load of the fatigue test and the tensile fatigue life test with the stress ratio of 0.1, the fatigue life of 10.9-grade and 12.9-grade high-strength bolts is more than 500 ten thousand times.
Most of the external structures of the existing bolts are uniform, and the processing technology of the bolts is simple, so that the processing quality of the bolts is influenced, the compression resistance and the tensile degree of the bolts are reduced, and the defects that the use requirements of people can not be well met are overcome.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a processing method of a high-fatigue-life and high-strength bolt, which solves the problems that most of bolt external structures proposed in the background art are uniform, the processing technology of the bolt is simple, the processing quality of the bolt is influenced, the compression resistance and the tensile degree of the bolt are reduced, the use requirements of people cannot be well met, and the like.
In order to achieve the purpose, the invention is realized by the following technical scheme: a processing method of high-fatigue-life and high-strength bolts is characterized in that 9 groups of different high-strength bolts are selected, and the method specifically comprises the following 9 types: 8.8-grade alloy steel outer hexagon bolts; 10.9 grade alloy steel outer hexagon bolts; 12.9-grade alloy steel outer hexagon bolts; 8.8 grade cylindrical head screw; 10.9 grade cylindrical cap screw; 12.9 grade cylinder head screw; 8.8 grade flange face bolts; 10.9 grade flange face bolts; grade 12.9 flange face bolts.
Optionally, the socket cap screw is specifically divided into an inner hexagon socket cap screw, an inner hexagon socket cap screw and an inner twelve-flower socket cap screw.
Optionally, the flange face bolts are specifically divided into outer hexagonal flange face bolts, outer dodecagonal flange face bolts, inner hexagonal flange face bolts and inner hexagonal flange face bolts.
Optionally, the material composition of the 10.9-grade and 12.9-grade high-fatigue-life high-strength bolts meets the following ranges (%):
optionally, the processing requirements of the material are as follows:
the grain size is more than or equal to 9 grades, the grades of various non-metallic inclusions are less than or equal to 1.5 grades, the total decarburization layer depth of the surface of the material is not more than 1 percent of the diameter of the material, the surface scratch and indentation depth is not more than 0.1mm, and the defects of lugs, folding, cracks, scabbing and the like cannot exist on the surface.
Optionally, the diameter range of the high-strength bolt is M12-30, the high-strength bolt is precisely formed by adopting a cold heading or hot heading process, a thread is not processed by rolling before heat treatment, and the thread is formed by rolling or rolling after heat treatment.
Optionally, the specific steps are as follows:
the method comprises the steps of raw material inspection, annealing, primary drawing, annealing, fine drawing, molding, dephosphorization, heat treatment, grinding, tooth pattern rolling, cleaning, shot blasting reinforcement, surface treatment, screening, inspection and packaging.
Optionally, the specific process parameters of the heat treatment are as follows:
the bolt dephosphorizes until 5 percent ammonium molybdate solution detects no reddish brown color;
the feeding thickness of the mesh belt furnace is less than or equal to 4 cm;
quenching heating temperature: 850-920 ℃;
quench heating time (min): bolt diameter (mm) number of layers 1.7 x 2;
carbon potential of quenching heating controlled atmosphere: 0.3 to 0.4;
cooling property of the rapid quenching oil: the maximum cooling temperature is 590-630 ℃, the maximum cooling speed is 105 ℃/s, and the cooling speed at 300 ℃ is 8-14 ℃/s;
the working temperature of the rapid quenching oil is 65-75 ℃, the stirring speed is 1.5-2.5 m/s, and the bolt is soaked in the oil for 8-15 minutes;
tempering and heating temperature: 610-640 ℃;
tempering heating time (min): quenching and heating time is plus 60;
nitrogen protection is used during tempering, the nitrogen flow is 20m3/h, and the nitrogen purity is 99.9%;
water cooling is carried out after tempering, and the water temperature is 40-60 ℃;
when the invention is produced on a heat treatment mesh belt furnace production line, the anti-collision measures are adopted in the whole flow of feeding → cleaning → dephosphorization → cleaning → quenching heating → quenching cooling → deoiling → cleaning → tempering heating → tempering cooling → discharging, and the anti-collision measures comprise: the polyurethane flexible boards with the thickness of 10mm are laid on each hopper and the polyurethane flexible boards with the thickness of 10mm which can swing left and right are hung, when the bolts fall, the bolts firstly impact on the flexible boards and then roll on the mesh belt of the next step.
Optionally, the grinding process specifically comprises the following steps:
the grinding allowance is 0.03-0.05 mm, and the feeding amount of a single grinding wheel is 0.03 mm;
the working speed is 80-150 r/min (M8-M20 bolt).
Optionally, the specific process parameters of shot blasting reinforcement are as follows:
the method is characterized in that a full-automatic crawler-type rolling shot blasting machine is adopted, the shot blasting machine is subjected to frequency conversion control, the shot blasting amount is 200Kg/min at most, the rated current of the shot blasting machine is 22A, the shot blasting machine can be adjusted by 5A-22A during working, the rated loading capacity of the shot blasting machine is 400KG, and the shot blasting machine is provided with a screw conveyor, a lifter and a dust removal system;
(1) adopting an S110 type alloy steel shot, wherein the hardness of the steel shot is 40-50 HRC, and the diameter of the steel shot is 0.3 mm;
(2) the shot blasting loading capacity is 100-150 Kg;
(3) adjusting the frequency of the shot blasting machine according to the current of the shot blasting machine, wherein the current is 19-21A during shot blasting strengthening work;
(4) the rotating speed of the crawler belt is 5 m/min;
(5) the loading capacity is 150-200 Kg during shot blasting, wherein 150-160 Kg is loaded on bolts of M6-M12, and 170-200 Kg is loaded on bolts of M14-M20;
(6) the shot blasting time is 15-25 minutes, wherein the bolts of M6-M12 are 20-25 minutes, and the bolts of M14-M20 are 15-20 minutes, so that the coverage rate is 200%;
(7) and before shot blasting, the workpiece is subjected to alkaline degreasing treatment at the temperature of below 60 ℃, and is dried.
The invention provides a processing method of a high-fatigue-life and high-strength bolt, which has the following beneficial effects:
the high fatigue life and high strength bolt performs spheroidizing annealing and drawing on the material meeting the corresponding index, and then performs forming processing to produce the bolt meeting the requirements of shape, size and tolerance; the anti-collision treatment of the bolt is well carried out in the production process; the tensile strength range of the 10.9-grade bolt is 1150-1250 MPa, the hardness is 35-37 HRC, the elongation after fracture is more than or equal to 10%, the reduction of area is more than or equal to 50%, the impact absorption energy (-20 ℃) is more than or equal to 40J, and when 46% of the tensile strength is the maximum loading load of a fatigue test and the tensile fatigue life test with the stress ratio of 0.1, the fatigue life of the bolt is more than 20 ten thousand times; the tensile strength range of the 12.9-grade bolt is 1250-1290 MPa, the hardness is 39-41 HRC, the elongation after fracture is more than or equal to 10%, the reduction of area is more than or equal to 48%, the impact absorption energy (-20 ℃) is more than or equal to 40J, and the fatigue life of the bolt is more than 20 ten thousand times when 46% of the tensile strength is the maximum loading load of a fatigue test and the tensile fatigue life test with the stress ratio of 0.1.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments.
The invention provides a technical scheme that: a processing method of high-fatigue-life and high-strength bolts selects 9 groups of different high-strength bolts, and specifically comprises the following 9 types:
8.8-grade alloy steel outer hexagon bolts; 10.9 grade alloy steel outer hexagon bolts; 12.9-grade alloy steel outer hexagon bolts; 8.8 grade cylindrical head screw; 10.9 grade cylindrical cap screw; 12.9 grade cylinder head screw; 8.8 grade flange face bolts; 10.9 grade flange face bolts; grade 12.9 flange face bolts.
The socket cap screw is specifically divided into an inner hexagon socket cap screw, an inner hexagon socket cap screw and an inner twelve-flower socket cap screw.
The flange face bolts are specifically divided into outer hexagonal flange face bolts, outer dodecagonal flange face bolts, inner hexagonal flange face bolts and inner hexagonal flange face bolts.
The material composition of the 10.9-grade and 12.9-grade high-fatigue-life high-strength bolts meets the following ranges (%):
the processing requirements of the material are as follows:
the grain size is more than or equal to 9 grades, the grades of various non-metallic inclusions are less than or equal to 1.5 grades, the total decarburization layer depth of the surface of the material is not more than 1 percent of the diameter of the material, the surface scratch and indentation depth is not more than 0.1mm, and the defects of lugs, folding, cracks, scabbing and the like cannot exist on the surface.
The diameter range of the high-strength bolt is M12-30, the high-strength bolt is precisely formed by adopting a cold heading or hot heading process, the bolt is not rolled and processed with threads before heat treatment, and the threads are formed by rolling or rolling after heat treatment.
The method comprises the following specific steps:
the method comprises the steps of raw material inspection, annealing, primary drawing, annealing, fine drawing, molding, dephosphorization, heat treatment, grinding, tooth pattern rolling, cleaning, shot blasting reinforcement, surface treatment, screening, inspection and packaging.
The specific process parameters of the heat treatment are as follows:
the bolt dephosphorizes until 5 percent ammonium molybdate solution detects no reddish brown color;
the feeding thickness of the mesh belt furnace is less than or equal to 4 cm;
quenching heating temperature: 850-920 ℃;
quench heating time (min): bolt diameter (mm) number of layers 1.7 x 2;
carbon potential of quenching heating controlled atmosphere: 0.3 to 0.4;
cooling property of the rapid quenching oil: the maximum cooling temperature is 590-630 ℃, the maximum cooling speed is 105 ℃/s, and the cooling speed at 300 ℃ is 8-14 ℃/s;
the working temperature of the rapid quenching oil is 65-75 ℃, the stirring speed is 1.5-2.5 m/s, and the bolt is soaked in the oil for 8-15 minutes;
tempering and heating temperature: 610-640 ℃;
tempering heating time (min): quenching and heating time is plus 60;
nitrogen protection is used during tempering, the nitrogen flow is 20m3/h, and the nitrogen purity is 99.9%;
water cooling is carried out after tempering, and the water temperature is 40-60 ℃;
when the invention is produced on a heat treatment mesh belt furnace production line, the anti-collision measures are adopted in the whole flow of feeding → cleaning → dephosphorization → cleaning → quenching heating → quenching cooling → deoiling → cleaning → tempering heating → tempering cooling → discharging, and the anti-collision measures comprise: the polyurethane flexible boards with the thickness of 10mm are laid on each hopper and the polyurethane flexible boards with the thickness of 10mm which can swing left and right are hung, when the bolts fall, the bolts firstly impact on the flexible boards and then roll on the mesh belt of the next step.
The grinding process comprises the following specific steps:
the grinding allowance is 0.03-0.05 mm, and the feeding amount of a single grinding wheel is 0.03 mm;
the working speed is 80-150 r/min (M8-M20 bolt).
The specific process parameters of shot blasting reinforcement are as follows:
the method is characterized in that a full-automatic crawler-type rolling shot blasting machine is adopted, the shot blasting machine is subjected to frequency conversion control, the shot blasting amount is 200Kg/min at most, the rated current of the shot blasting machine is 22A, the shot blasting machine can be adjusted by 5A-22A during working, the rated loading capacity of the shot blasting machine is 400KG, and the shot blasting machine is provided with a screw conveyor, a lifter and a dust removal system;
(1) adopting an S110 type alloy steel shot, wherein the hardness of the steel shot is 40-50 HRC, and the diameter of the steel shot is 0.3 mm;
(2) the shot blasting loading capacity is 100-150 Kg;
(3) adjusting the frequency of the shot blasting machine according to the current of the shot blasting machine, wherein the current is 19-21A during shot blasting strengthening work;
(4) the rotating speed of the crawler belt is 5 m/min;
(5) the loading capacity is 150-200 Kg during shot blasting, wherein 150-160 Kg is loaded on bolts of M6-M12, and 170-200 Kg is loaded on bolts of M14-M20;
(6) the shot blasting time is 15-25 minutes, wherein the bolts of M6-M12 are 20-25 minutes, and the bolts of M14-M20 are 15-20 minutes, so that the coverage rate is 200%;
(7) and before shot blasting, the workpiece is subjected to alkaline degreasing treatment at the temperature of below 60 ℃, and is dried.
In summary, the processing method of the high fatigue life and high strength bolt comprises the following specific steps during use:
the method comprises the steps of raw material inspection, annealing, primary drawing, annealing, fine drawing, molding, dephosphorization, heat treatment, grinding, tooth pattern rolling, cleaning, shot blasting reinforcement, surface treatment, screening, inspection and packaging.
The specific process parameters of the heat treatment are as follows:
the bolt dephosphorizes until 5 percent ammonium molybdate solution detects no reddish brown color;
the feeding thickness of the mesh belt furnace is less than or equal to 4 cm;
quenching heating temperature: 850-920 ℃;
quench heating time (min): bolt diameter (mm) number of layers 1.7 x 2;
carbon potential of quenching heating controlled atmosphere: 0.3 to 0.4;
cooling property of the rapid quenching oil: the maximum cooling temperature is 590-630 ℃, the maximum cooling speed is 105 ℃/s, and the cooling speed at 300 ℃ is 8-14 ℃/s;
the working temperature of the rapid quenching oil is 65-75 ℃, the stirring speed is 1.5-2.5 m/s, and the bolt is soaked in the oil for 8-15 minutes;
tempering and heating temperature: 610-640 ℃;
tempering heating time (min): quenching and heating time is plus 60;
nitrogen protection is used during tempering, the nitrogen flow is 20m3/h, and the nitrogen purity is 99.9%;
water cooling is carried out after tempering, and the water temperature is 40-60 ℃;
when the invention is produced on a heat treatment mesh belt furnace production line, the anti-collision measures are adopted in the whole flow of feeding → cleaning → dephosphorization → cleaning → quenching heating → quenching cooling → deoiling → cleaning → tempering heating → tempering cooling → discharging, and the anti-collision measures comprise: the polyurethane flexible boards with the thickness of 10mm are laid on each hopper and the polyurethane flexible boards with the thickness of 10mm which can swing left and right are hung, when the bolts fall, the bolts firstly impact on the flexible boards and then roll on the mesh belt of the next step.
The grinding process comprises the following specific steps:
the grinding allowance is 0.03-0.05 mm, and the feeding amount of a single grinding wheel is 0.03 mm;
the working speed is 80-150 r/min (M8-M20 bolt).
The specific process parameters of shot blasting reinforcement are as follows:
the method is characterized in that a full-automatic crawler-type rolling shot blasting machine is adopted, the shot blasting machine is subjected to frequency conversion control, the shot blasting amount is 200Kg/min at most, the rated current of the shot blasting machine is 22A, the shot blasting machine can be adjusted by 5A-22A during working, the rated loading capacity of the shot blasting machine is 400KG, and the shot blasting machine is provided with a screw conveyor, a lifter and a dust removal system;
(1) adopting an S110 type alloy steel shot, wherein the hardness of the steel shot is 40-50 HRC, and the diameter of the steel shot is 0.3 mm;
(2) the shot blasting loading capacity is 100-150 Kg;
(3) adjusting the frequency of the shot blasting machine according to the current of the shot blasting machine, wherein the current is 19-21A during shot blasting strengthening work;
(4) the rotating speed of the crawler belt is 5 m/min;
(5) the loading capacity is 150-200 Kg during shot blasting, wherein 150-160 Kg is loaded on bolts of M6-M12, and 170-200 Kg is loaded on bolts of M14-M20;
(6) the shot blasting time is 15-25 minutes, wherein the bolts of M6-M12 are 20-25 minutes, and the bolts of M14-M20 are 15-20 minutes, so that the coverage rate is 200%;
(7) and before shot blasting, the workpiece is subjected to alkaline degreasing treatment at the temperature of below 60 ℃, and is dried.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (10)
1. A processing method of a high-fatigue-life and high-strength bolt is characterized by comprising the following steps: the selection of 9 groups of different high-strength bolts is specifically divided into the following 9 types:
8.8-grade alloy steel outer hexagon bolts; 10.9 grade alloy steel outer hexagon bolts; 12.9-grade alloy steel outer hexagon bolts; 8.8 grade cylindrical head screw; 10.9 grade cylindrical cap screw; 12.9 grade cylinder head screw; 8.8 grade flange face bolts; 10.9 grade flange face bolts; grade 12.9 flange face bolts.
2. The method for processing the high-fatigue-life high-strength bolt according to claim 1, wherein the method comprises the following steps: the cylindrical head screw is specifically divided into an inner hexagonal cylindrical head screw, an inner hexagonal cylindrical head screw and an inner twelve-flower cylindrical head screw.
3. The method for processing the high-fatigue-life high-strength bolt according to claim 1, wherein the method comprises the following steps: the flange face bolts are specifically divided into outer hexagonal flange face bolts, outer dodecagonal flange face bolts, inner hexagonal flange face bolts and inner hexagonal flange face bolts.
4. The method for processing the high-fatigue-life high-strength bolt according to claim 1, wherein the method comprises the following steps: the material composition of the 10.9-grade and 12.9-grade high-fatigue-life high-strength bolts meets the following ranges (%):
5. the method for processing the high-fatigue-life high-strength bolt according to claim 1, wherein the method comprises the following steps: the processing requirements of the material are as follows:
the grain size is more than or equal to 9 grades, the grades of various non-metallic inclusions are less than or equal to 1.5 grades, the total decarburization layer depth of the surface of the material is not more than 1 percent of the diameter of the material, the surface scratch and indentation depth is not more than 0.1mm, and the defects of lugs, folding, cracks, scabbing and the like cannot exist on the surface.
6. The method for processing the high-fatigue-life high-strength bolt according to claim 1, wherein the method comprises the following steps: the diameter range of the high-strength bolt is M12-30, the high-strength bolt is precisely formed by adopting a cold heading or hot heading process, the bolt is not subjected to rolling processing before heat treatment to form threads, and the threads are formed by rolling or rolling after heat treatment.
7. The method for processing the high-fatigue-life high-strength bolt according to claim 1, wherein the method comprises the following steps: the method comprises the following specific steps:
the method comprises the steps of raw material inspection, annealing, primary drawing, annealing, fine drawing, molding, dephosphorization, heat treatment, grinding, tooth pattern rolling, cleaning, shot blasting reinforcement, surface treatment, screening, inspection and packaging.
8. The method for processing the high-fatigue-life high-strength bolt according to claim 1, wherein the method comprises the following steps: the specific process parameters of the heat treatment are as follows:
the bolt dephosphorizes until 5 percent ammonium molybdate solution detects no reddish brown color;
the feeding thickness of the mesh belt furnace is less than or equal to 4 cm;
quenching heating temperature: 850-920 ℃;
quench heating time (min): bolt diameter (mm) number of layers 1.7 x 2;
carbon potential of quenching heating controlled atmosphere: 0.3 to 0.4;
cooling property of the rapid quenching oil: the maximum cooling temperature is 590-630 ℃, the maximum cooling speed is 105 ℃/s, and the cooling speed at 300 ℃ is 8-14 ℃/s;
the working temperature of the rapid quenching oil is 65-75 ℃, the stirring speed is 1.5-2.5 m/s, and the bolt is soaked in the oil for 8-15 minutes;
tempering and heating temperature: 610-640 ℃;
tempering heating time (min): quenching and heating time is plus 60;
nitrogen protection is used during tempering, the nitrogen flow is 20m3/h, and the nitrogen purity is 99.9%;
water cooling is carried out after tempering, and the water temperature is 40-60 ℃;
when the invention is produced on a heat treatment mesh belt furnace production line, the anti-collision measures are adopted in the whole flow of feeding → cleaning → dephosphorization → cleaning → quenching heating → quenching cooling → deoiling → cleaning → tempering heating → tempering cooling → discharging, and the anti-collision measures comprise: the polyurethane flexible boards with the thickness of 10mm are laid on each hopper and the polyurethane flexible boards with the thickness of 10mm which can swing left and right are hung, when the bolts fall, the bolts firstly impact on the flexible boards and then roll on the mesh belt of the next step.
9. The method for processing the high-fatigue-life high-strength bolt according to claim 1, wherein the method comprises the following steps: the grinding process comprises the following specific steps:
the grinding allowance is 0.03-0.05 mm, and the feeding amount of a single grinding wheel is 0.03 mm;
the working speed is 80-150 r/min (M8-M20 bolt).
10. The method for processing the high-fatigue-life high-strength bolt according to claim 1, wherein the method comprises the following steps: the specific process parameters of shot blasting reinforcement are as follows:
the method is characterized in that a full-automatic crawler-type rolling shot blasting machine is adopted, the shot blasting machine is subjected to frequency conversion control, the shot blasting amount is 200Kg/min at most, the rated current of the shot blasting machine is 22A, the shot blasting machine can be adjusted by 5A-22A during working, the rated loading capacity of the shot blasting machine is 400KG, and the shot blasting machine is provided with a screw conveyor, a lifter and a dust removal system;
(1) adopting an S110 type alloy steel shot, wherein the hardness of the steel shot is 40-50 HRC, and the diameter of the steel shot is 0.3 mm;
(2) the shot blasting loading capacity is 100-150 Kg;
(3) adjusting the frequency of the shot blasting machine according to the current of the shot blasting machine, wherein the current is 19-21A during shot blasting strengthening work;
(4) the rotating speed of the crawler belt is 5 m/min;
(5) the loading capacity is 150-200 Kg during shot blasting, wherein 150-160 Kg is loaded on bolts of M6-M12, and 170-200 Kg is loaded on bolts of M14-M20;
(6) the shot blasting time is 15-25 minutes, wherein the bolts of M6-M12 are 20-25 minutes, and the bolts of M14-M20 are 15-20 minutes, so that the coverage rate is 200%;
(7) and before shot blasting, the workpiece is subjected to alkaline degreasing treatment at the temperature of below 60 ℃, and is dried.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111872638A (en) * | 2020-07-24 | 2020-11-03 | 上海宏挺紧固件制造有限公司 | Screw machining process |
| CN116877555A (en) * | 2023-06-05 | 2023-10-13 | 中船海为高科技有限公司 | Double-end stud for connecting wind turbine generator blade root and processing method thereof |
| WO2024016482A1 (en) * | 2022-07-22 | 2024-01-25 | 七丰精工科技股份有限公司 | Ultrahigh-strength alloy steel, 19.8-grade threaded fastener and preparation method therefor |
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