Background technology
Along with becoming increasingly conspicuous of the energy and environmental problem; And people's raising that the security of car, reliability, comfortableness etc. are required, each big automaker make great efforts from the structure design of improving automobile with seek the weight that new two aspects of equivalent material alleviate automobile; Update and adopt new part manufacturing process, improve the quality of product.The research of super-high strength steel and use have improved the collision performance of automobile, have realized light-weighted requirement.But super-high strength steel at room temperature deformability is very poor.On the one hand, super-high strength steel plate intensity is high, viscous deformation narrow range at room temperature, and required stamping press is big, easy of crack; On the other hand, the part resilience increases after the drawing, causes accessory size and shape stability variation.Therefore traditional cold stamping method is difficult to solve the problem that super-high strength steel runs in the body of a motor car manufacturing.In recent years, the foreign scholar developed a kind of new super-high strength steel plate heating forming technology-hot press-formed technology.In hot stamping technology; Super-high strength steel plate plate is heated to austenitizing temperature (900~950 ℃) in process furnace; And kept 5 minutes in the austenitic area; Then plate is transferred to pressing machine; In press tool, carry out drawing and quenching simultaneously, make formation of parts obtain 100% martensitic stucture.Compare with other forming technologies, the hot press-formed of plate has the following advantages: resistance to deformation is little, plasticity good, forming limit is high, be easy to shaping; Can produce the workpiece with complex geometric shapes, formation of parts has good dimensional precision; Be equipped with the proper heat treatment mode, can make its best performance of plate performance, for automobile provides high-quality component.In addition; The up-to-date laser assembly solder plate hot stamping technology that puts forward is welded the high-strength steel of different mechanical attributes or different thickness together; Carry out hot press-formedly then, can obtain on the one hand to weld reduction car body weight that strip comes, improve assembly precision, simplify advantages such as installation step; Take into account hot press-formed advantage on the other hand, further improve the plasticity of super-high strength steel plate and the dimensional precision of the finished product, thereby improve the automobile anti-collision, satisfy the active demand of safety and energy-saving and emission-reduction better.
Chinese patent CN101288889 discloses " a kind of superstrength steel hot moulding process and forming mould "; This mould comprises upper bolster and is fixed on punch, the die shoe on the upper bolster and is fixed on the die on the die shoe; Be provided with cooling-water duct in the die, cooling-water duct is connected with a cooling water recirculation system.Chinese patent CN201231286Y discloses a kind of " body of a motor car part hot stamping forming die ", and this mould comprises upper plate, lower shoe, die, punch, holding pad.Cooling fluid flows at punch, die profile internal recycle.Punch, die adopt insert structure, and insert material is selected high-intensity hot-work die steel for use.The part of technology that such patent is carried and mould structure production only has high strength, can't satisfy the requirement of crashproof type of part energy absorption capacity.
Chinese patent CN101486062A discloses a kind of " thermoforming of high-duty steel part and edge-cutting integrated technique and mould "; This mould comprises upper die and lower die, goes up side cut instrument and following side cut instrument; The upper end that in upper and lower mould, is provided with the cooling water channel patrix is equipped with upper mould oil cylinder; The piston rod of upper mould oil cylinder is connected with last side cut instrument; The bottom of counterdie is equipped with lower mold oil cylinder; The piston rod of lower mold oil cylinder is connected with the lower end of a push rod, and the upper end of push rod is connected with following side cut instrument.This structure utilizes the side cut instrument of mould inside that the thermoforming part is cut edge.This technology has increased the complexity of hot-forming die, and shearforce and shear position receive the restriction of hot-forming die structure.
Chinese patent CN101717850A discloses " thermal treatment splicing process and device before a kind of ultrahigh-strength steel plates punching press "; This technology according to the performance requriements of the part that will be shaped, utilize the different types of cooling to heat-treat to ultrahigh-strength steel plates demands of different zone.This device comprises different refrigerating modules and insulation annealing module, and each module closely is arranged in together.This invention can make the different zones of same steel plate have different mechanical propertys, obtains the amalgamation steel plate that performance everywhere there are differences.What this invention obtained is the different amalgamation steel plate of performance, for the different formation of parts of obtained performance, needs to combine follow-up cold punching technology.Outside operation is loaded down with trivial details, because the restriction of contrive equipment can't obtain complex class, performance and splice part arbitrarily.
The Chinese patent CN101961744A manufacturing process and the device thereof of plate " welding ", this technology and device can be realized the combination of different thickness in the part, strength steel sheet, thereby improve the energy absorption capacity of part when reducing car weight.But the welding technology also has its defective: the mobile meeting of weld seam causes the mobile meeting of steel formability performance decrease, weld seam to cause the wearing and tearing of die surface, laser welding equipment to cost an arm and a leg.
Summary of the invention
The objective of the invention is for overcoming the deficiency of above-mentioned prior art; Provide a kind of super-high strength steel high temperature to splice quenching formed technology and device; The heat passage of degree varies carried out in the different zone of part in shaping and mould internal cooling process; Make the intensity and the hardness of formation of parts to distribute as required; Realize the high strength of material and the perfect adaptation of energy absorption capacity, and can reduce investment of devices, reduced production process; Enhance productivity, quality product is easy to control.
For realizing above-mentioned purpose, the present invention adopts following technical proposals:
A kind of super-high strength steel high temperature splices quenching formed technology, may further comprise the steps:
1) electrically heated rod is switched on; Rely on temperature controlling system to gather the temperature information of thermopair, and then the break-make of relay, thus 400~500 ℃ of the die temperatures of acquisitions needs; Under this temperature, be incubated 5~10 minutes, guarantee mould temperature uniform distribution everywhere;
2) open waterworks simultaneously, guarantee the cooling water channel water flow stationary;
3) thermopair timing acquiring temperature information, temperature is up to standard everywhere to guarantee mould;
4) hardenable super-high strength steel is heated to 930~950 ℃ and be incubated 3~5 minutes abundant austenitizings, the super-high strength steel with heating takes out from process furnace and is positioned on the steady brace of die face afterwards, and punch comes downwards to bottom dead centre, is incubated 10~15s.In this process; Part by super-high strength steel is made is heat-treated with the different types of cooling in shaping and mould internal cooling process need, for high strength, high rigidity zone (territory, stagnant zone of part), adopts the steel cooling to insert; Guarantee speed of cooling greater than 27 ℃/s, generate martensitic stucture; And, then adopt insulation to insert for low strength, soft zone (the energy-absorbing zone of part), and guarantee speed of cooling less than 27 ℃/s, generate bainite even pearlitic structure; Carry out temperature control targetedly at shaping with after being shaped; Insulation inserted be heated to 400~500 ℃; The rate of cooling of steel plate diminishes, and obtains that intensity reduces and ductility is better organized, thereby guarantees that the part thermoforming back different zones that finishes has the different mechanical performance;
5) insulation finishes, and protruding, die separates, and naturally cools to room temperature behind the taking-up formation of parts.
A kind of super-high strength steel high temperature splices quenching formed device; Comprise punch and die, punch is fixed by punch retainer, and die is fixed by die block; Punch retainer is connected with top mold frame, following mould bases respectively with die block, and mould bases is led by the guide pillar guide pin bushing up and down; Said punch and die are all inserted by one at least and are formed, between punch and the punch retainer, be respectively equipped with one deck thermostable heat-isolating coating layer between die and the die block; Temperature element is set respectively on said punch and the die, and temperature element links to each other with temperature controlling system.
Said punch and die be the one-piece steel structure for being made up of heating zone and cooling zone all.
Said punch and die are the formula steel design of inserting, and it comprises that heating is inserted and cooling is inserted, and between heating is inserted and cooling is inserted heat insulation gap are arranged.
Said punch and die are the formula steel design of inserting, and it comprises that heating inserts and cooling is inserted, and heating is inserted and cooled off has special thermal insulation ceramics between inserting.
Said punch and die are the formula structure of inserting, and it is inserted to insert with steel cooling by special ceramics and combines.
Said punch and die are the formula structure of inserting, and it is inserted and combined by the special ceramics heating cooling of inserting with steel.
Between said punch and the punch retainer, all match between die and the die block, between punch and the punch retainer, all fastening between die and the die block through lateral screw through oat tail groove structure.
Said die face is equipped with the dog screw that the top is semisphere, retractable.
Be provided with cooling-water duct in said punch and the die, the cooling water intakeoutfall joint is installed on the cooling channel, but the water entrance joint connects water-supply pipe and water pump.
In said punch and the die heating tube is set, said heating tube links to each other with the temperature controller of temperature controlling system.
The high temperature that the present invention is directed to the super-high strength steel formation of parts splices quenching formed technology; The heat passage of degree varies carried out in the different zone of part in shaping and mould internal cooling process; Make the intensity and the hardness of formation of parts to distribute as required, realized the high strength of material and the perfect adaptation of energy absorption capacity.The present invention can be applicable to the production of automobile collision preventing class part (collision prevention girders, A post, B post, body platform passage etc.).
Hardenable super-high strength steel is heated to 930~950 ℃ and be incubated 3~5 minutes abundant austenitizings, and the super-high strength steel plate with heating takes out from process furnace and is positioned on the steady brace of die face afterwards, and punch comes downwards to bottom dead centre, is incubated 10~15s.In this process; Part is heat-treated with the different types of cooling in shaping and mould internal cooling process need, for high strength, high rigidity zone (territory, stagnant zone of part), adopts the steel cooling to insert; Guarantee speed of cooling greater than 27 ℃/s, generate martensitic stucture; And, then adopt insulation to insert for low strength, soft zone (the energy-absorbing zone of part), and guarantee speed of cooling less than 27 ℃/s, generate bainite even pearlitic structure.Carry out temperature control targetedly at shaping with after being shaped; Insulation inserted be heated to 400~500 ℃; The rate of cooling of steel plate diminishes, and obtains that intensity reduces and ductility is better organized, thereby guarantees that the part thermoforming back different zones that finishes has the different mechanical performance;
This device is that a cover high temperature splices quenching formed mould, and invention is primarily aimed at punch, die and punch retainer, die block and temperature controlling system.Punch is fixed by punch retainer, and die is fixed by die block.Punch retainer is connected with top mold frame, following mould bases respectively through screw with die block, leads through the guide pillar guide pin bushing between the mould bases up and down.
Punch is spliced by one and above inserting as required, and the different type of cooling, type of heating even material are adopted in different inserting.Be evenly distributed at the steel plate thickness direction in order to ensure temperature, and warpage does not take place, the heating of die, the type of cooling and material are corresponding with punch.
Punch adopts following several array mode: (one) one-piece steel punch wherein is divided into heating zone and cooling zone; (2) the formula steel punch of inserting wherein is divided into heating and inserts, cools off and insert, and adopts one deck special ceramics heat insulation between heating is inserted and cooling is inserted; (3) the formula steel punch of inserting wherein is divided into heating and inserts, cools off and insert, and heating is inserted and cooled off and adopt the gap of certain distance heat insulation between inserting; (4) the formula punch of inserting, the cooling that wherein is divided into ceramic insert, steel is inserted; (5) the formula punch of inserting is divided into wherein that ceramic heat is inserted, the cooling of steel is inserted.The array mode of die is corresponding with it.Under the same conditions, the speed of cooling of combination (one) heating zone is the fastest, and the speed of cooling of cooling zone is the slowest; The speed of cooling of combination (five) heating zone is the slowest, and the speed of cooling of cooling zone is the fastest.In five kinds of array modes, the heat-insulating property that insulation is inserted improves from array mode () to (five) gradually.Array mode is selected according to actual production part needs.
For being convenient for changing punch, match through oat tail groove structure between punch and the punch retainer, carry out fastening through lateral screw between punch and the punch retainer.Corresponding die is handled according to same case.
The die face is equipped with the dog screw of retractable, and the screw top is a semisphere, reduced and steel plate between contact area, reduced scattering and disappearing of heat.
The punch of cooling water channel need be set, the cooling water intakeoutfall joint is installed on the cooling-water duct, joint connects water-supply pipe and water pump, and cooling water channel is taken away heat through swiftly flowing current, thereby reaches the purpose of partial heat treatment.Corresponding die is handled according to same case.
For making exemplar; Ceramic insert is selected high glass pottery Macor for use, and this material has the favorable mechanical processing characteristics, and has advantages such as thermal conductivity is low, specific heat is high, the coefficient of expansion is little; Greatly reducing and contact heat passage between the steel plate, is that a kind of insulation annealing of excellent property is inserted.For batch process, ceramic insert is selected high tenacity, high-flexural strength and high-wearing feature, excellent heat-proof quality, the zirconium white ZrO2 pottery that thermal expansivity approaches steel for use.
Adopt one deck special ceramics heat insulation between heating is inserted and cooling is inserted, this pottery is selected high glass pottery Macor for use.
Scribble thermostable heat-isolating coating between punch and the punch retainer, effectively reduce the punch calorific loss.
The punch of heating unit need be set, heating tube is installed.This heating tube is shell with the metal tube, and heating alloy at one end has outlet line and in metal tube, loads closely knit magnesia powder dielectric as heating element, with fixing heating element.
Selected heating tube is cylindrical, needs the little 0.1mm in aperture of heating on its aperture ratio mould.
Heating temperature is different everywhere because of mould, so need adopt temperature measuring equipment when heating.The present invention adopts external K type nickel chromium-nickel silicon thermocouple, 0~1300 ℃ of temperature-measuring range.Through grooves protruding, the die top and bottom thermopair is installed in the place apart from punch-die closing face 2mm, is used for measuring temperature protruding, die.
This K type thermopair links to each other with temperature controller through compensation lead of thermocouple, and temperature value measured is intuitively shown.
This temperature controller has a plurality of extended terminals, can be connected with a plurality of thermopairs.
This temperature controller links to each other with immerging metal tube heater, can export the break-make that steering order changes the controller rly. through comparing (computing) back according to the difference of observed value and set(ting)value (target value); The regulative mode of controller adopts PID control, and good stability can be eliminated static difference automatically.The principle of work of Controlling System:
Thermopair is an electrical signal input instrument with temperature transition; After instrument is handled signal (amplification, nonlinear compensation); One the road delivers to display circuit shows; After comparing, another road and set(ting)value obtain temperature error; Compare the break-make that output steering order in (computing) back changes the gauge internal rly. according to this error by predetermined regulative mode then, thereby to reach the purpose that changes external heater working order control die temperature.
Punch-die of the present invention the insert material that adopts different heat physical properties, the different heating and the types of cooling; Rely on the PID temperature controlling system; Make the super-high strength steel plate of heating behind the austenitizing be shaped and the pressurize process of cooling in different zones be in different speed of cooling; Thereby obtain different microtextures; Finally obtain the different splicing part of performance everywhere; Realized any splicing of high strength and high energy absorption capacity, and the mechanical property of high intensity region and hypo-intense regions of guaranteeing steel plate is in the splice region even transition.This invention can reduce investment of devices, reduces production process, enhances productivity, and quality product is easy to control.
Embodiment
Below in conjunction with accompanying drawing and instance the present invention is further specified.
The upper surface that punch retainer 1 of the present invention cooperates with top mold frame is processed with groove, and groove floor is drilled with the through hole of some diameter 2.5mm, in order to laying thermopair 12.Scribble thermostable heat-isolating coating 6 in punch retainer 1 dovetail-indent.Punch retainer one side has some screwed screw holes, with the convenient screw retention punch 2,11 that passes through.The structure of die block 5 is corresponding with the structure of punch retainer 1.
Punch cooling is inserted and is provided with cooling water channel 3 in 2, and cooling water channel 3 connects through connecting water pipe.Even as far as possible in order to guarantee mold surface temperature; Cool off the inside of inserting at punch and be provided with a plurality of prosopyles and a plurality of posticum, cooling water channel 3 one sides are the prosopyle, and a side is a posticum; The prosopyle links to each other with water pump through water pipe, and posticum links to each other with the water coolant recovery system.Punch cooling is inserted and is provided with several and the straight hole of punch retainer 1 corresponding diameter 2.5mm, and from being 2mm, the thermocouple induction end is surveyed the temperature of punch 2 here, and temperature information is sent to temperature controlling system apart from the punch identity distance in the straight hole lower end.Lay a plurality of thermopairs, can monitor punch 2 temperature conditionss in a plurality of zones.Die cooling is inserted, and to cool off 2 the structure of inserting corresponding for 4 structure and punch.
Die is provided with 4 steady braces 10, and steady brace 10 tops are spherical, and steady brace 10 can be flexible to die 5 internal freedoms, prevents to heat the temperature decline that steel plate causes with die 5 too early contacts.
Punch heating is inserted and 11 is provided with several electric heating tubes, and selected heating tube is cylindrical, needs the little 0.1mm in aperture of heating on its aperture ratio mould, and the heating tube that is adopted is the single head electric heating tube, confirms the power of heating tube according to the required Heating temperature of mould.Insert 9 structure of die heating is corresponding with 11.
Thermopair links to each other with temperature controlling system, and temperature controller can be exported the break-make that steering order changes the controller rly. through comparing (computing) back according to the difference of observed value and set(ting)value (target value); The regulative mode of controller adopts PID control.
Certain U type beam with shown in Figure 8 is an example, and this beam fore-end is born shock load, and requirement must have enough energy absorption capacities; Rear end part links to each other with wheel house, and requirement must have enough rigidity.According to principle of the present invention, fore-end must be shaped under certain heat-retaining condition, guarantees that speed of cooling is enough slow; Rear end part must satisfy certain heat transfer condition, guarantees that speed of cooling is enough fast.Owing to the present invention proposes five kinds of protruding, die array modes, promptly (one) one-piece steel punch wherein is divided into heating zone and cooling zone; (2) the formula steel punch of inserting wherein is divided into heating and inserts, cools off and insert, and adopts one deck special ceramics heat insulation between heating is inserted and cooling is inserted; (3) the formula steel punch of inserting wherein is divided into heating and inserts, cools off and insert, and heating is inserted and cooled off and adopt the gap of certain distance heat insulation between inserting; (4) the formula punch of inserting, the cooling that wherein is divided into ceramic insert, steel is inserted; (5) the formula punch of inserting is divided into wherein that ceramic heat is inserted, the cooling of steel is inserted.The array mode of die is corresponding with it.Under the same conditions, the speed of cooling of combination (one) heating zone is the fastest, and the speed of cooling of cooling zone is the slowest; The speed of cooling of combination (five) heating zone is the slowest, and the speed of cooling of cooling zone is the fastest.In five kinds of array modes, the heat-insulating property that insulation is inserted improves from array mode () to (five) gradually.Array mode is selected according to actual production part needs.
Wherein back two kinds of relative first three have better heat-insulating property.Therefore this instance adopts the first three in five kinds of protruding, die array modes to contrast checking, thereby illustrates this implementation of processes mode, and the validity of proof invention.
With electrically heated rod energising, rely on temperature controlling system to gather the temperature information of thermopair, and then the break-make of relay, thus 400 ℃ of the die temperatures of acquisitions needs.Insulation is 5 minutes under this temperature, guarantees mould temperature uniform distribution everywhere.Open waterworks simultaneously, guarantee the cooling water channel water flow stationary.Thermopair timing acquiring temperature information, temperature is up to standard everywhere to guarantee mould.Hardenable super-high strength steel plate is heated to 930~950 ℃ and be incubated 5 minutes abundant austenitizings; To heat the super-high strength steel plate afterwards takes out from process furnace and is positioned on the steady brace; Punch comes downwards to bottom dead centre; Insulation 10s heat-treats in this process steel plate and protruding, the die combination of selecting for use.Insulation finishes, and protruding, die separates, and naturally cools to room temperature behind the taking-up formation of parts.
Longitudinally temperature distribution history is as shown in Figure 9 near zone of transition for three kinds of protruding, die array mode lower steel plates.It is thus clear that it is best that array mode (three) adopts the gap heat insulation and preservation effect in three kinds of array modes, speed of cooling is the slowest.
According to relevant research document, the cooling curve of steel plate under different mould Heating temperatures as shown in figure 10.It is thus clear that, the mould temperature 360 ℃ and more than, 25 ℃/s of corresponding steel plate speed of cooling can guarantee to get into the bainite transformation zone, yield strength can reach 500~550MPa, tensile strength can reach 600~700MPa, can satisfy the actual needs of U type beam collision energy-absorbing.The punch that has cooling water channel cools off the temperature of inserting and remains on below 50 ℃; Corresponding steel plate speed of cooling is greater than 50 ℃/s; Austenite is converted into martensitic stucture fully; Yield strength can reach 1000~1250MPa; Tensile strength reaches 1500~1750MPa, satisfies the needs of U type beam collision protection distortion fully.Figure 11 gets into the tissue topography that generates behind the bainite transformation district for steel plate, and Figure 12 gets into the tissue topography that generates behind the martensite range for steel plate, and the microtexture pattern has also been verified the macro-mechanical property that is shown.