CN108213864A - The method and its bolt of bolt processing - Google Patents
The method and its bolt of bolt processing Download PDFInfo
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- CN108213864A CN108213864A CN201711373843.6A CN201711373843A CN108213864A CN 108213864 A CN108213864 A CN 108213864A CN 201711373843 A CN201711373843 A CN 201711373843A CN 108213864 A CN108213864 A CN 108213864A
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- 238000012545 processing Methods 0.000 title claims abstract description 81
- 238000000034 method Methods 0.000 title claims abstract description 64
- 238000005096 rolling process Methods 0.000 claims abstract description 38
- 238000010438 heat treatment Methods 0.000 claims abstract description 34
- 239000002994 raw material Substances 0.000 claims abstract description 16
- 230000007704 transition Effects 0.000 claims abstract description 14
- 230000008859 change Effects 0.000 claims description 33
- 229910000734 martensite Inorganic materials 0.000 claims description 15
- 238000005496 tempering Methods 0.000 claims description 15
- 238000010791 quenching Methods 0.000 claims description 14
- 230000000171 quenching effect Effects 0.000 claims description 14
- 239000003795 chemical substances by application Substances 0.000 claims description 13
- 238000005507 spraying Methods 0.000 claims description 12
- 238000011282 treatment Methods 0.000 claims description 12
- 239000011324 bead Substances 0.000 claims description 7
- 238000000465 moulding Methods 0.000 claims description 7
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- 239000002184 metal Substances 0.000 claims description 4
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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
- F16B35/00—Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Heat Treatment Of Articles (AREA)
- Forging (AREA)
Abstract
The present invention is suitable for field of mechanical technique, provides the method and its bolt of a kind of processing of bolt, the method for the bolt processing, including：A, the raw material of predetermined processing bolt is subjected to cold pier processing, makes that the head of the bolt is molded and the bar portion of the bolt is preforming, and increases the head and the first radius of the transition arc of the bar portion junction, preforming bolt is made；B, the temperature for improving heat treatment is heat-treated the preforming bolt, improves the yield strength of the preforming bolt；C, thread rolling processing is carried out to completing the heat treatment preforming bolt, is molded the bar portion of the bolt, and increase the second radius of the circular arc at the tooth bottom of screw thread in the bar portion of the bolt, the bolt is made.Whereby, the present invention is realized is increased to stress-number of cycles N=10 by the probable life of bolt7。
Description
Technical field
The method and its bolt processed the present invention relates to field of mechanical technique more particularly to a kind of bolt.
Background technology
Using steel high-strength bolt as representative, general stress-number of cycles N=5 × 106, for a long time, China's high intensity
There are short life, poor reliability and the structures three major issues such as again for bolt.Three major issues seriously restrict high-end automobile mechanical equipment
Development and safety are on active service.High-strength bolt determines that high-end automobile mechanical equips main linkage function, embodies automobile mechanical equipment
Service life, reliability and economy can ability to bear, be high-end machine-building core.
In summary, the method that existing bolt is processed is in actual use, it is clear that there is inconvenient and defect, it must so having
It is improved.
Invention content
For it is above-mentioned the defects of, the purpose of the present invention is to provide a kind of bolt processing method and its bolt, improve spiral shell
The probable life of bolt.
To achieve these goals, the present invention provides a kind of method of bolt processing, including：
A, the raw material of predetermined processing bolt is subjected to cold pier processing, the head of the bolt is made to be molded and the bolt
Bar portion is preforming, and increases the head and the first radius of the transition arc of the bar portion junction, is made preforming
Bolt；
B, the temperature for improving heat treatment is heat-treated the preforming bolt, improves the preforming bolt
Yield strength；
C, thread rolling processing is carried out to completing the heat treatment preforming bolt, is molded the bar portion of the bolt, and
Increase the second radius of the circular arc at the tooth bottom of the screw thread in the bar portion of the bolt, the bolt is made.
According to the method, the method further includes：
D, the surface of the bolt to completing thread rolling processing is carried out at bead and/or spraying stable friction factor agent
Reason.
According to the method, in the step A, the head is made to be combined with the bar portion in the cold pier processing
The metallic fiber flow direction at place is smooth；And the head of increased first radius and the fixed connector of the bolt is mutually fitted
Match；
In the step C, the tooth form part metals of the screw thread in the bar portion of the bolt are made in thread rolling processing
Fiber flow direction is smooth；And increased second radius is adapted with the internal thread of the fixed connector of the bolt.
According to the method, the step B includes：
B1, the scheduled cool time is being maintained, is improving hardening heat and the preforming bolt is quenched
Processing includes lath martensite tissue and gill shape martensitic structure after making the tissue change of the preforming bolt；
B2, maintaining scheduled tempering time, improve temperature to after quenching treatment it is described it is pre- into
The bolt of type carries out temper, includes secondary troostite after making the tissue change of the preforming bolt.
According to the method, 10 DEG C~20 DEG C of the ranging from heating of the hardening heat is improved；Improve the tempering temperature
2 DEG C~7 DEG C of the ranging from heating of degree.
According to the method, the bolt is hexagon-headed bolt；
In the step B1, the heating value of the hardening heat is 15 DEG C, and the preforming bolt is quenched
Processing makes the tissue change of the preforming bolt include lath martensite tissue and gill shape martensitic structure；
In the step B2, the heating value of the temperature is 5 DEG C, to described preforming after quenching treatment
Bolt carry out temper, make the preforming bolt tissue change include secondary troostite.
According to the method, the bolt be hexagon-headed bolt be the hexagon-headed bolt of M5 × 0.8 × 125 or M5 ×
The hexagon-headed bolt of 0.8 × 150 hexagon-headed bolt or M5 × 0.8 × 143.5, strength grade is 9.8 grades；
In the step A, the first radius of the transition arc of the bar portion junction is increased to by 0.2mm~0.3mm
0.4mm~0.5mm；
In the step C, the second radius of the circular arc at the tooth bottom of the screw thread in the bar portion of the bolt by 0.10 mm~
0.13mm increases to 0.13mm~0.16mm；
In the step B1, the scheduled cool time is 60 minutes, and the hardening heat is 860 ± 10 DEG C；
In the step B2, the scheduled tempering time is 120 minutes, and the temperature is 475 ± 10 DEG C.
According to the method, it is steady that spraying friction coefficient is carried out on the surface that described pair is completed the bolt that thread rolling is processed
The step of determining agent processing includes：According to the degree of roughness on the surface for completing the bolt that thread rolling is processed, in the table of the bolt
The stable friction factor agent of face spraying adaptation.
According to the method, the spraying stable friction factor agent is surface lubricant.
In order to realize another goal of the invention of the present invention, method processing described above is utilized the present invention also provides a kind of
Bolt.
The present invention by will be heat-treated processed by thread rolling after be changed to thread rolling processing before, the plastic deformation for utilizing raw material is former
Reason under external force or the effect of powerful pressure and certain speed, forces raw material to be squeezed along mold cavity (i.e. filament plate) extrusion forming
The thread surface of pressure rear bolt forms compressive pre-stress layer due to flow harden, and threaded portion tension stress when product uses, can
To offset a part of stress, heavily stressed effect is proposed so as to reach.In addition, cold-heading processing after product formed due to flow harden should
Power layer, if carrying out thread rolling processing again, i.e. thread forming process has Stress superposition, and there are failure risks.Therefore thread rolling processing
Before carry out heat treatment can eliminate cold-heading processing form stressor layers due to flow harden.The raw material of predetermined processing bolt is subjected to cold pier
In process, increase the head and the first radius of the transition arc of the bar portion junction, since the alternation of cross-section is more sharp
Strong, the factor of stress concentration is bigger, and the probability of product failure is bigger, therefore uses the first radius of larger transition arc,
The change for making section is slow as possible, reduces stress concentration, eliminates the failure risk brought by size factor；It is heat-treated by improving
Temperature the preforming bolt is heat-treated, improve the yield strength of the preforming bolt；To completing at heat
It manages the preforming bolt and carries out thread rolling processing, be molded the bar portion of the bolt, increase the spiral shell in the bar portion of the bolt
Second radius of the circular arc at trough between the tooth bottom of line, i.e. two ridges, the change for making section is slow as possible, and reducing should
Power is concentrated, and eliminates the failure risk brought by size factor, the bolt is made, and improves the probable life of bolt to Cyclic Stress
Times N=107。
Description of the drawings
Fig. 1 is the method flow diagram of the bolt processing in the embodiment of the present invention；
Fig. 2A is the bolt arrangement schematic diagram in the embodiment of the present invention；
Fig. 2 B are the head of the bolt in the embodiment of the present invention and the partial enlarged view of bar portion junction；
Fig. 2 C are the longitudinal section enlarged drawings of screw thread at A in Fig. 2A；
Fig. 3 A are the head of the bolt in the embodiment of the present invention and the metallograph of bar portion junction metallic fiber flow direction；
Fig. 3 B are the metallographs of the form of thread metallic fiber flow direction of the bolt in the embodiment of the present invention；
Fig. 4 is the bolt tension load stress axonometric projection in the embodiment of the present invention；
Fig. 5 is that bolt tightens schematic diagram in the embodiment of the present invention；
Fig. 6 is the relationship histogram of bolt torque in the embodiment of the present invention-tighten angle value；
Fig. 7 A are the tempered sorbite schematic illustration of tissue after bolt tempering processing in the prior art；
Fig. 7 B are the tempered sorbite schematic illustration of tissue after bolt tempering processing in the embodiment of the present invention；
Fig. 8 is bolted structure diagram in the embodiment of the present invention.
Specific embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to the accompanying drawings and embodiments, it is right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
Referring to Fig. 1, Fig. 2A~Fig. 2 C, in the first embodiment of the present invention, the present invention provides a kind of side of bolt processing
Method, including：
In step S101, the raw material of predetermined processing bolt is subjected to cold pier processing, make the bolt head 10 be molded with
And the bar portion 30 of the bolt is preforming, and increases the first of the head 10 and the transition arc of 30 junction of bar portion
Preforming bolt is made in radius R1；
In step S102, the temperature for improving heat treatment is heat-treated the preforming bolt, improve it is described it is pre- into
The yield strength of the bolt of type；
In step S103, thread rolling processing is carried out to completing the heat treatment preforming bolt, makes the bar portion of the bolt
30 moldings, and increase the second radius R2 of the circular arc at the tooth bottom of screw thread 40 in the bar portion 30 of the bolt, the spiral shell is made
Bolt.
In this embodiment, in step S101, the raw material of predetermined processing bolt is subjected to cold pier processing, makes the bolt
Head 10 is molded and the bar portion of the bolt 30 is preforming, and cold-heading refers to that implementing forging to metal material at normal temperatures adds
Work reaches associated shape, a kind of forging and stamping processing technology of size.Since the alternation of cross-section is fiercer, the factor of stress concentration is bigger,
The probability of product failure is bigger, and failure is referred in engineering, and the function that parts lose original design defined is known as failing,
Failure includes completely losing original function, function reduction and has major injury or hidden danger, is continuing with that reliability and peace can be lost
Quan Xing.Therefore increase the head 10 and the first radius R1 of the transition arc of 30 junction of bar portion, make the change in section
As possible slowly, reduce stress concentration, eliminate because size factor brings the risk of product failure；It is former using the plastic deformation of raw material
Reason under external force or the effect of powerful pressure and certain speed, forces raw material along mold cavity (i.e. filament plate) extrusion forming,
A kind of pressure processing method for referring to being allowed to generate plastic deformation by the power applied material more than its yield limit is squeezed,
40 surface of screw thread for squeezing rear bolt forms compressive pre-stress layer due to flow harden, and 40 part tension of screw thread should during product use
Power can offset a part of stress, and heavily stressed effect is proposed so as to reach.Stress refer to object due to external cause (such as stress) and
During deformation, the internal force of interaction is generated between each section in object, the internal force on unit area is known as stress.It is in addition, cold
Product forms stressor layers due to flow harden after upsetting processing, if carrying out thread rolling processing again, i.e., 40 molding procedure of screw thread, which has, answers
Power is superimposed, and there are failure risks.Therefore, cold-heading processing can be eliminated by step S102 heat treatments being carried out before step S103 thread rollings are processed
Stressor layers are formed due to flow harden, meanwhile, the temperature of heat treatment is improved during being heat-treated to described preforming
Bolt is heat-treated, so as to improve the yield strength of the preforming bolt；To completing to be heat-treated the preforming spiral shell
Bolt carries out thread rolling processing, is molded the bar portion 30 of the bolt, and increases the tooth of the screw thread 40 in the bar portion 30 of the bolt
Second radius R2 of the circular arc at bottom, the change for making section is slow as possible, reduces stress concentration, eliminates because size factor brings product
The bolt is made in the risk of failure.
In the second embodiment of the present invention, the method further includes：
The surface of the bolt to completing thread rolling processing carries out bead and/or the agent processing of spraying stable friction factor
The step of.
In this embodiment, bead is also referred to as shot peening strengthening, be reduce bolt fatigue, improve the service life effective ways it
One, bead is exactly that High-velocity Projectiles stream is ejected into the surface of bolt, is plastically deformed the surface layer of bolt, and forms one
Determine the strengthening layer of thickness, higher residual stress is formed in strengthening layer, due to the presence of the bearing stress of bolt, when bolt is held
A part of stress can be offset when loaded, so as to improve the fatigue strength of bolt.After bead, on the one hand, make product table
Face forms compressive pre-stress layer, to reduce the tensile stress for being easiest to be formed fatigue crack, so as to improve surface strength；On the other hand,
Product can strengthen the binding force of product matrix and coating after bead, ensure that the friction stability of product surface meets product
Surface anticorrosive performance, the friction coefficient of product surface and appearance requirement.
Exactly two and multiple parts are linked together for the purpose using bolt fastening, are gone as a part
Movement is without failing.Its essence be fastening after to have enough clamping forces, ensure in axial external applied load, two parts regardless of
From；Load lateral out, two parts do not slide.When connection cannot fully complete this clamping function, this connection just fails.
Therefore, the probable life of bolt how is improved using failure angle research from bolt.Referring to Fig. 4, design tool is utilized --- it is tight
Be connected capacity axonometric projection (that is, stress/strain figure) i.e. Fig. 4, and the tightening technique of joint bolt carries out stress load point to bolt
Analysis.In Fig. 4, FM is in use, clamping force suffered when bolt elongate amount is △ L when being fastenedly connected by bolt；Δ L is is pressing from both sides
Under clamp force FM effects, the length variation of bolt；Δ T is the thickness change that part is clamped under clamping force FM effects；Straight line 1. table
Show the stiffness slope of bolt, the rigidity of fastener is bigger, and slope value is bigger；2. straight line represents the stiffness slope of clamped part,
The rigidity for being clamped part is bigger, and slope absolute value is bigger.As Δ T=0, connector decrement is zero, then connector not by
Power represents that bolt loses fastening function.Common bolt tightening technique includes：1. moment of torsion control method (T)；2. torque-corner control
Preparation method (TA) is also known as super-elasticity control methods；3. yield point control methods (TAY) are by taking calibrated wrench method as an example.
In one embodiment of the invention, referring to Fig. 6 and Fig. 8, the longevity is used to improving bolt with 1. moment of torsion control method (T)
The mounting means of life is studied.As can be seen from Figure 6, the tightening technique of moment of torsion control method or process are that pre-screwing → elasticity is twisted
Tightly → plasticity is tightened.Wherein, pre-screwing is the stage that bolt is bonded with connected piece；It is the stage really fastened that elasticity, which is tightened,；
And plasticity is tightened, and is the stage that bolt starts to fail or be plastically deformed, and then represents to need replacing bolt into this stage.Root
According to ISO 16047, with conservation of energy principle, the relationship between torque and clamping force is explained, formula is as follows：
Wherein：F is the pretightning force of bolt, and T is the torque applied, and P is screw pitch, and π is circumference
Rate, α be 40 helix angle of screw thread, μtFor 40 friction coefficient of screw thread, RtFor the effective friction radius of bolt, μbFor bolt or nut
Head lower flange face friction coefficient, Rb：10 effective friction radius of bolt head, with reference to Fig. 4 tensile load stress axonometric projections and Fig. 4
It tightens schematic diagram and understands bolt in use, being applied to the total torque T on bolt by torque spanner, a part is used for overcoming bolt
Friction torque Tb between first 10 bottom support surface and clamped part 20, the T of loss about 50%；On the other hand it is used for overcoming bolt thread
With the friction torque Tt between the screw thread of connected piece 50, the T of loss about 40%, remaining energy is converted to effective clamping force F.
It is the target that the probable life for extending bolt is realized premised on fastening reliability that reliable fastening, which is coupled, makes its probable life
Higher than projected life, even integeral vehicle life, it is whole vehicle functions, is able to one of primary condition ensured safely.It is kept according to energy
Permanent principle, knows from above-mentioned formula, after the scheme of cold-heading processing determines, pitch P, screw thread effective radius Rt, bolt effectively rubs
Wipe radius RbIt is definite value, the friction coefficient μ that maximum factor is product is influenced on tight conditiontot、μt、μb, wherein μtot=f
(μt, μb), the friction coefficient μ of producttotIt is bigger than normal, overcome the torque energy T that frictional force consumes just more, be converted into effective clamping force
If F is small to a certain extent, being clamped part just has loosening risk, therefore, need to ensure fastening function, consider further that fatigue failure.Instead
It, total friction coefficient μtotLess than normal, clamping force F will increase, and when reaching a certain level, that is, be more than the bearing capacity of bolt, spiral shell
Bolt will be pulled off failure.So only under the conditions of rational clamping force F, two are made to link together with multiple parts, as
Under the premise of one part equally goes movement without failure, the probable life of ability accurate validation fatigue life, i.e. bolt can be used
Service life refers to the cumulative operation time or work times that should reach under defined use condition, be product durability with
The important indicator of quality, is usually represented with working time or cycle-index, also known as working life.Know from above-mentioned formula, when cold
After the scheme of upsetting processing determines, pi therein, bolt lift angle α, pitch P, screw thread effective radius Rt, bolt effectively rubs
Radius Rb, torque T be definite value, therefore to tight condition, i.e. clamping force F influences the friction coefficient that maximum factor is product
μtot、μt、μb, wherein μtot=f (μt, μb).According to above-mentioned analysis, in a preferred embodiment of the invention, in execution of step
After S103, after the size sizing of bolt, the surface of bolt is surface-treated, the surface of appropriate raising bolt is rubbed
Coefficient is wiped, is beneficial to the raising of bolt service life.Wherein, the bolt of the method processing of the bolt processing is turret head spiral shell
Bolt；The bolt is that hexagon-headed bolt is the hexagon-headed bolt of M5 × 0.8 × 125, and strength grade is 9.8 grades, described to complete
The surface for the bolt processed into thread rolling include the step of spraying stable friction factor agent processing：Add according to thread rolling is completed
The degree of roughness on the surface of the bolt of work, in the stable friction factor agent that the surface spraying of the bolt is adapted to, it is preferred that
The stable friction factor agent of spraying increases stable friction factor agent (i.e. surface lubricant), and the trade mark of the surface lubricant is
B06JA+E10A reduces single batch friction coefficient scattered error range.During detection, using 6.3Nm as end condition, realistic simulation assembling,
Survey each item data, the PVvalue testing result after change as shown in 3~table of table 4, wherein, table 3 be change after friction system
Number test result, the data statistics of the friction coefficient after 4 changes of table, knows from 3~table of table 4, and the bolt after change is suffered to be clamped
The test result of power (i.e. fastening force) can be seen that fastening force suffered by bolt in yield force hereinafter, not only stable friction factor exists
(μ in a certain rangetot=0.09~0.14), and the control of the scattered error of single batch is in≤0.03 range, it will be apparent that better than table 1~
PVvalue testing result before changing shown in table 2.Wherein, table 1 for PVvalue testing before changing as a result, the change of 2, table
More preceding coefficient of friction data statistics,
Table 1
Table 2
Table 3
Table 4
In the third embodiment of the present invention, referring to Fig. 2A~Fig. 2 C, in the step S101, processed in the cold pier
In make the metallic fiber flow direction of the head and the bar portion junction smooth；And the increased first radius R1 with it is described
The head 10 of the fixed connector of bolt is adapted；
In the step S103, the tooth form of the screw thread 40 in the bar portion 30 of the bolt is made in thread rolling processing
Part metals fiber flow direction is smooth；And the internal thread 40 of the increased second radius R2 and the fixed connector of the bolt
It is adapted.
In this embodiment, in the step S101, according to cold upsetting die of car and raw material used in the cold pier processing
Between the frictional force size that contacts, the extrusion passes in the adjustment cold pier processing ensure the product symbol that each station types it out
Design requirement size and shape is closed, that is, ensures that each station well with perfect cold-heading molding, successfully realizes that the cold-heading of product is pre-
Molding, most important one qualifying point are to flow the metallic fiber flow direction on the head 10 and 30 junction of bar portion
Freely without any folding, prevent potential crack source (at the E in Fig. 2 B, 3A), and the increased first radius R1 and institute
The head 10 for stating the fixed connector of bolt is adapted, with M5 × 0.8 × 125, M5 × 0.8 × 150, M5 × 0.8 × 143.5 6
For hex bolt series, referring to Fig. 2A, under the premise of 40 performance of screw thread is ensured, the transition circle of 30 junction of bar portion
First radius R1 of arc increases to 0.4mm~0.5mm by 0.2mm~0.3mm；In the case where not influencing assembling so that first
Radius R1 is big as possible, and the change for making section is slow as possible, reduces stress concentration, eliminates because size factor brings the wind of product failure
Danger.For example, M5 × 0.8 × 125 hexagon-headed bolt by the first the half of the transition arc of 30 junction of bar portion of prior art processing
Diameter R1 is 0.2mm, in an embodiment of the invention, can be increased to 0.4mm, 0.45mm or 0.5mm etc..Or
First radius R1 of the transition arc of 30 junction of person's bar portion is 0.4mm, can be increased to 0.45mm or 0.5mm
Deng.In the step S103, mold (i.e. filament plate) and workpiece material (i.e. cold-heading semi-finished product) in being processed according to the thread rolling
Between the frictional force size that contacts, the speed that adjustment metal material flow along mold cavity, ensure thread rolling process in screw thread into
Type quality, even if the tooth form part metals fiber flow direction of screw thread 40 in the bar portion 30 of the bolt is smooth, without any folding,
Prevent potential crack source, (at the F in Fig. 2 C, 3B)；And the increased second radius R2 and the bolt are fixed
The internal thread 40 of connector is adapted, with M5 × 0.8 × 125, M5 × 0.8 × 150, the turret head series spiral shell of M5 × 0.8 × 143.5
For bolt, under the premise of 40 performance of screw thread is ensured, the of the circular arc at the tooth bottom of the screw thread 40 in the bar portion 30 of the bolt
Two radius R2 increase to 0.13mm~0.16mm by 0.10mm~0.13mm；In the case where not influencing assembling so that the second half
Diameter R2 is big as possible, and the change for making section is slow as possible, reduces stress concentration, eliminates because size factor brings the wind of product failure
Danger.For example, it is by the second radius R2 of the circular arc at the tooth bottom of the screw thread 40 in the bar portion 30 of the bolt of prior art processing
0.10mm in an embodiment of the invention, can be increased to 0.13mm, 0.14mm or 0.16mm etc.；Or
Second radius R2 of the circular arc at the tooth bottom of screw thread 40 is 0.13mm, increases to 0.14mm, 0.15mm or 0.16mm etc..When
So, it is applied equally to the processing of the hexagon-headed bolt of other specifications.
In the fourth embodiment of the present invention, the step S102 includes：
B1, the scheduled cool time is being maintained, is improving hardening heat and the preforming bolt is quenched
Processing includes lath martensite tissue and gill shape martensitic structure after making the tissue change of the preforming bolt；
B2, maintaining scheduled tempering time, improve temperature to after quenching treatment it is described it is pre- into
The bolt of type carries out temper, includes secondary troostite after making the tissue change of the preforming bolt.
In this embodiment, there is certain relationship between the yield strength of material and fatigue strength, it is however generally that, material
Yield strength is higher, and fatigue strength is also higher, therefore, product fatigue strength is improved to reach by improving product yield strength
Purpose improves the yield strength of product by improving the temperature for quenching and being tempered.Specifically, in step B1, remaining scheduled
In the case of cool time, improve hardening heat and quenching treatment is carried out to the preforming bolt, make the preforming bolt
Tissue change after include lath martensite tissue and gill shape martensitic structure；Preferably, the hardening heat is improved
10 DEG C~20 DEG C of ranging from heating；More particularly, the heating value of the hardening heat is 15 DEG C, to described preforming
Bolt carries out quenching treatment, and the tissue change of the preforming bolt is made to include lath martensite tissue and gill shape geneva
Body tissue.In step B2, scheduled tempering time is being maintained, is improving temperature to the institute after quenching treatment
It states preforming bolt and carries out temper, include secondary troostite after making the tissue change of the preforming bolt.It is preferred that
, improve 2 DEG C~7 DEG C of the ranging from heating of the temperature；More particularly, the heating value of the temperature is 5
DEG C, temper is carried out to the preforming bolt after quenching treatment, becomes the tissue of the preforming bolt
Change includes secondary troostite.Preferably, in the step B1, the scheduled cool time is 60 minutes, the quenching
Temperature is 860 ± 10 DEG C；In the step B2, the scheduled tempering time is 120 minutes, and the temperature is 475
±10℃。
| Process | Before changing | After change |
| It quenches (temperature × time) | 845 ± 10 DEG C × 60 minutes | 860 ± 10 DEG C × 60 minutes |
| It is tempered (temperature × time) | 470±10℃×120 | Tempering 475 ± 10 DEG C × 120 |
Table 5
Referring to above-mentioned table 5, by adjusting heat treatment process parameter, the tissue obtained after quenching treatment is about 90% lath-shaped
Martensitic structure and gill shape martensitic structure, what is obtained after temper is organized as secondary troostite.Without temperature
Bolt metallograph after the tempering processing of heating as shown in Figure 7 A, carries out the bolt after the tempering processing of temperature heating
Metallograph is as shown in Figure 7 B.Under the premise of guarantee bolt strength and hardness do not decline, the toughness of product is improved, reaches raising production
The purpose of product service life.Tissue before changing is tempered sorbite, and the tissue after change is secondary troostite, when tempering Soxhlet
During the hardness phase of body and secondary troostite, the yield tensile ratio of secondary troostite is higher than the yield tensile ratio of tempered sorbite, i.e. tempering is bent
Family name's body has higher yield strength, in terms of comprehensive mechanical property, intensity, plasticity and the toughness higher of secondary troostite, and fatigue
Service life is more preferable.After heat treatment process parameter, the mechanics properties testing Comparative result of bolt including tensile strength, is bent
Intensity and hardness are taken as shown in the following table 6 and table 7, table 6 is the performance indicator for changing front bolt, and table 7 is the property for changing rear bolt
It can index.It can be seen that from table 6 and table 7, change forward and backward tensile strength RMIt is held essentially constant with hardness, but bending after change
Take intensity RP0.2It is significantly increased, yield strength RP0.2Integral level improves >=1000MPa from≤1000MPa.
Table 6
Table 7
Reliably fastening is that whole vehicle functions, safety are able to one of primary condition ensured to bolt, and using fastening reliability as
Target reaches and extends the probable lifes of various bolts as effect, to the conducts such as fastener, fastening mechanism, fastening method and equipment
System research development is its important foundation.As fastener producer, not only to consider fastener uses position, new car
Which kind of property failure caused during experiment in what manner, it is also contemplated that the failure that may occur in being used for a long time, and thoroughly solve
The failure of removal that may occur in all kinds of long-time services extends the probable life of various bolts, make its probable life higher than whole
The vehicle service life is the key that the present invention.One aspect of the present invention manufactures angle from bolt, by adjusting process route, that is, is heat-treated work
Before sequence after thread rolling by being changed to thread rolling, i.e., process be adjusted to by " cold-heading processing → thread rolling processing → heat treatment " " cold-heading processing →
Heat treatment → thread rolling processing ", meanwhile, it finds out each process Key Quality and wants vegetarian refreshments；On the other hand, it is ground from bolt using failure angle
Study carefully the probable life for improving bolt, with M5 × 125, for 9.8 grades of hexagon-headed bolt, ensure bolt stress for 6.38 ±
1.4KN, frequency are under the conditions of 89.4HZ, fatigue stress cycle-index reaches 107When, bolt does not fail still.Prior art scheme,
By taking 40 fastener of steel screw thread as an example, stress-number of cycles only can reach N=5 × 106, bolt provided in an embodiment of the present invention adds
The probable life of Steel Bolt can be increased to N=10 by the method for work7.The side of bolt processing provided in an embodiment of the present invention
Method can equally be well applied to the processing of the bolt of other various sizes and intensity.
In one embodiment of the invention, processing process is as follows：
With M5 × 125,9.8 grades of hexagon-headed bolt is representative, and the technological process of bolt is：Raw material prepare → it is (2) cold
Upsetting is processed, and → → (4) thread rolling processing (screw thread 40 is molded) → being (5) surface-treated → is (6) always examined and packaging for (3) heat treatment.
Step (1)：Raw material prepare：According to actually required line footpath and the trade mark used, prepare material.Material is SWCH45K
(JIS G 3507), line footpath
Step (2)：Cold-heading is processed：Molding and bar portion 30 of this process for bolt head 10 are preforming.Its key control will
Element is the first radius R1 of increase.
Step (3)：Heat treatment：Meet the comprehensive mechanical property requirement of product.Mechanical property element is heat-treated to bend to improve
Take intensity.
Step (4)：40 molding procedures of screw thread, that is, thread rolling processing：The final shaping unit of 30 screw thread 40 of bar portion.Thread rolling processing dimension will
It asks to increase the second radius R2.
Step (5)：Surface treatment procedure：Meet the surface anticorrosive performance of product, the friction coefficient of product surface and outer
See requirement.Surface state element is reduces single batch friction coefficient scattered error range.
Step (6)：Total inspection and packaging：According to fabrication evaluation size, mechanical property, corrosion resistance and appearance etc., wrapped after qualified
Dress, delivery.
By adjusting qualifying point in process, each step of optimization, the probable life success of bolt should by original
Power cycle-index N=5 × 106It has been increased to N=107, reached the probable life of the various automobile bolts of extension, perfect public affairs
Product line is taken charge of, customer demand has been better met, has improved the competitiveness of product in market, be more advantageous to the market of marketing personnel
Developing.The vehicle factor promoted the use of at present has Volkswagen, and there is BOSCH series etc. in parts factory.It is ground by above-mentioned
Study carefully, reach and ensure bolt under the conditions of stress is 6.38 ± 1.4KN, frequency is 89.4HZ, fatigue stress cycle-index reaches
107When, purpose that bolt does not fail still.
Table 8
Table 9
Laboratory report of the above-mentioned table 8 for bolt fatigue strength before changing, table 9 are the experiment report for changing rear bolt fatigue strength
It accuses, above-mentioned result of the test is shown, M5 × 125,9.8 grades of hexagon-headed bolt, is 6.38 ± 1.4, frequency 89.4HZ in stress
Under the premise of, fatigue stress cycle-index reaches 107When, bolt does not fail yet.Thus it will be obvious, provided by the present invention
Bolt processing method processing bolt, service life obtained significant raising.
In other embodiments of the invention, it also provides and is made using the method that the bolt in any of the above-described embodiment is processed
Bolt, the structure of specific processing method and bolt specifically described in above-mentioned multiple embodiments, and details are not described herein.
The connection signal of the bolt and connector as shown in figure 8, the bolt can be adapted for the occasion of various mechanical connections, particularly plus
Work requires higher automobile bolt.
In conclusion the present invention by will be heat-treated processed by thread rolling after be changed to thread rolling process before, utilize the modeling of raw material
Property deformation principle, under external force or the effect of powerful pressure and certain speed, force raw material crowded along mold cavity (i.e. filament plate)
Molded, the thread surface for squeezing rear bolt forms compressive pre-stress layer due to flow harden, and when product uses threaded portion by
Tensile stress can offset a part of stress, and heavily stressed effect is proposed so as to reach.In addition, cold-heading processing after product because cold-working it is hard
Change and form stressor layers, if carrying out thread rolling processing again, i.e. thread forming process has Stress superposition, and there are failure risks.Cause
This thread rolling processing before carry out heat treatment can eliminate cold-heading processing form stressor layers due to flow harden.By the original of predetermined processing bolt
Material is carried out in cold pier process, increases the head and the first radius of the transition arc of the bar portion junction, due to cutting
It is fiercer that face changes, and the factor of stress concentration is bigger, and the probability of product failure is bigger, therefore using larger transition arc
First radius, the change for making section is slow as possible, reduces stress concentration, eliminates the failure risk brought by size factor；Pass through
The temperature for improving heat treatment is heat-treated the preforming bolt, improves the yield strength of the preforming bolt；
Thread rolling processing is carried out to completing the heat treatment preforming bolt, the bar portion of the bolt is molded, increases the bolt
Second radius of the circular arc at trough between the tooth bottom of the screw thread in bar portion, i.e. two ridges, makes the change in section as possible
Slowly, reduce stress concentration, eliminate the failure risk brought by size factor, the bolt is made, improve the available longevity of bolt
Order stress-number of cycles N=107。
Certainly, the present invention can also have other various embodiments, without deviating from the spirit and substance of the present invention, ripe
It knows those skilled in the art and makes various corresponding changes and deformation, but these corresponding changes and change in accordance with the present invention
Shape should all belong to the protection domain of appended claims of the invention.
Claims (10)
- A kind of 1. method of bolt processing, which is characterized in that including：A, the raw material of predetermined processing bolt is subjected to cold pier processing, makes the head molding of the bolt and the bar portion of the bolt It is preforming, and increase the head and the first radius of the transition arc of the bar portion junction, preforming bolt is made；B, the temperature for improving heat treatment is heat-treated the preforming bolt, improves the surrender of the preforming bolt Intensity；C, thread rolling processing is carried out to completing the heat treatment preforming bolt, the bar portion of the bolt is made to be molded, and increase Second radius of the circular arc at the tooth bottom of the screw thread in the bar portion of the bolt, is made the bolt.
- 2. according to the method described in claim 1, it is characterized in that, the method further includes：D, the surface of the bolt to completing thread rolling processing carries out bead and/or the agent processing of spraying stable friction factor.
- 3. according to the method described in claim 1, it is characterized in that, in the step A, make in the cold pier processing described The metallic fiber flow direction on head and the bar portion junction is smooth；And increased first radius and the bolt are fixed The head of connector is adapted；In the step C, the tooth form part metals fiber of the screw thread in the bar portion of the bolt is made in thread rolling processing Flow direction is smooth；And increased second radius is adapted with the internal thread of the fixed connector of the bolt.
- 4. according to the method described in claim 3, it is characterized in that, the step B includes：B1, the scheduled cool time is being maintained, is improving hardening heat and quenching treatment is carried out to the preforming bolt, Include lath martensite tissue and gill shape martensitic structure after making the tissue change of the preforming bolt；B2, scheduled tempering time is being maintained, is improving temperature to described preforming after quenching treatment Bolt carries out temper, includes secondary troostite after making the tissue change of the preforming bolt.
- 5. according to the method described in claim 4, it is characterized in that, improve the ranging from heating 10 DEG C~20 of the hardening heat ℃；Improve 2 DEG C~7 DEG C of the ranging from heating of the temperature.
- 6. according to the method described in claim 5, it is characterized in that, the bolt is hexagon-headed bolt；In the step B1, the heating value of the hardening heat is 15 DEG C, and quenching treatment is carried out to the preforming bolt, The tissue change of the preforming bolt is made to include lath martensite tissue and gill shape martensitic structure；In the step B2, the heating value of the temperature is 5 DEG C, to the preforming spiral shell after quenching treatment Bolt carries out temper, and the tissue change of the preforming bolt is made to include secondary troostite.
- 7. according to the method described in claim 6, it is characterized in that, it is M5 × 0.8 × 125 6 that the bolt, which is hexagon-headed bolt, Either the hexagon-headed bolt of the hexagon-headed bolt of M5 × 0.8 × 150 or M5 × 0.8 × 143.5, strength grade are hex bolt 9.8 grade；In the step A, the first radius of the transition arc of the bar portion junction increases to 0.4mm by 0.2mm~0.3mm ~0.5mm；In the step C, the second radius of the circular arc at the tooth bottom of the screw thread in the bar portion of the bolt by 0.10mm~ 0.13mm increases to 0.13mm~0.16mm；In the step B1, the scheduled cool time is 60 minutes, and the hardening heat is 860 ± 10 DEG C；In the step B2, the scheduled tempering time is 120 minutes, and the temperature is 475 ± 10 DEG C.
- 8. according to the method described in claim 2, it is characterized in that, the surface of the bolt of thread rolling processing is completed at described pair The step of carrying out the agent processing of spraying stable friction factor includes：According to the coarse journey on the surface for completing the bolt that thread rolling is processed Degree, in the stable friction factor agent that the surface spraying of the bolt is adapted to.
- 9. according to the method described in claim 8, it is characterized in that, the spraying stable friction factor agent is surface lubricant.
- 10. a kind of bolt processed using claim 1~9 any one of them method.
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Cited By (4)
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| CN109604937A (en) * | 2018-11-09 | 2019-04-12 | 宾科汽车紧固件（昆山）有限公司 | The processing technology of oil circuit bolt |
| CN110142571A (en) * | 2019-05-22 | 2019-08-20 | 苏州泰润达发动机零部件有限公司 | A kind of processing method of bolt |
| CN111842774A (en) * | 2020-07-29 | 2020-10-30 | 苏州畅利永紧固件有限公司 | Outer hexagonal cross bolt machining process |
| CN112792519A (en) * | 2021-04-08 | 2021-05-14 | 北京铁科首钢轨道技术股份有限公司 | Cold forming automatic production system and production method for anchor bolt or T-shaped bolt |
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| CN112792519A (en) * | 2021-04-08 | 2021-05-14 | 北京铁科首钢轨道技术股份有限公司 | Cold forming automatic production system and production method for anchor bolt or T-shaped bolt |
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