CN104498688A - Flame straightening method of bogie frame of high speed train - Google Patents
Flame straightening method of bogie frame of high speed train Download PDFInfo
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- CN104498688A CN104498688A CN201410740711.2A CN201410740711A CN104498688A CN 104498688 A CN104498688 A CN 104498688A CN 201410740711 A CN201410740711 A CN 201410740711A CN 104498688 A CN104498688 A CN 104498688A
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Abstract
The invention relates to a flame straightening method of a bogie frame of a high speed train. The method comprises the following steps: calibrating an infrared thermometer according to the applied range of flame heating temperature parameters; adjusting the emissivity of the infrared thermometer according to the calibration result; positioning the infrared thermometer above a weathering steel flame straightening area; heating the flame straightening area through neutral flame of oxy-acetylene flame and monitoring the temperature of a central region of a heating area in real time through the infrared thermometer at the same time until the temperature of reaches 730 to 750 DEG C; maintaining for 3 to 5 minutes; and cooling by air. According to the method, the high-weatherability steel is straightened; the hardness and the strength of a base material in the flame straightening area are closest to those of the base material; the low-temperature impact energy of the metal in the straightening area is more than that of the base material, and the impact energy AKV is up to 200J under the test temperature of -40 DEG C, and is 2.5 times that of a test specimen prepared from the same material under the maximum heating temperature controlled to be 600 to 650 DEG C in the straightening area.
Description
Technical field
The invention belongs to truck frame of high-speed motor train unit manufacturing technology field, relate to a kind of Highs-speed motor train unit bogie welded frame flame shrinking method.
Background technology
Current EMU weathering steel bogie frame generally adopts mechanical means to correct welding residual deformation, and restriction uses flame shrinking technology.Basic reason is the hot rolling weather-resisting steel board that Highs-speed motor train unit bogie welded frame is selected, and it contains certain alloying constituent, as copper, phosphorus, chromium, nickel etc., makes susceptibility that such steel heat flame apparently higher than ordinary low-carbon steel.Also more shallow for the understanding of flame shrinking in current production, the control of Flame Heating Temperature is also more coarse, and the selection of Heating temperature also comparatively blindly.It is generally acknowledged: Flame Heating Temperature can be controlled between 600 ~ 800 DEG C.Temperature control method also mostly adopts tempilstick determination flame Heating Zone Temperature, does not often reach perfect condition.Once Flame Heating Temperature selection is improper or generation departs from more greatly, the mother metal performance of flame heating zone will be made to produce noticeable change, serious use properties and the safety in operation reducing bogie frame.Domestic enterprise adopts flame shrinking technique conscientiously not hold on high weather resistance steel framework product.Can on high weather resistance steel framework product, use flame shrinking technology well, key be: appropriately select and accurately control flame heating schedule parameter.The selection of producing Flame Heating temperature, often based on experience, controls inadequate science, and randomness is comparatively large, and technique is accurate not.Domestic also not about the relevant report of high weather resistance steel bogie frame flame shrinking technology at present.
Summary of the invention:
The technical problem to be solved in the present invention is to provide a kind of control science, technique is accurate, and the hardness of flame shrinking district mother metal and intensity can be made closest to mother metal, and low-temperature impact work is higher than the truck frame of high-speed motor train unit flame shrinking method of mother metal.
In order to solve the problems of the technologies described above, truck frame of high-speed motor train unit flame shrinking method of the present invention comprises the steps:
(1) according to Flame Heating Temperature parameter range of application, infrared thermometer is demarcated, obtain the corresponding relation of infrared thermometer emittance and probe temperature, obtain 730 ~ 750 DEG C of corresponding emittance λ according to emittance and the corresponding relation of probe temperature; Adjustment infrared thermometer makes its emittance equal λ;
(2) on workpiece, draw weathering steel flame shrinking district profile, infrared thermometer is placed in above weathering steel flame shrinking district;
(3) with oxyacetylene torch neutral flame, flame shrinking district is heated, carry out Real-Time Monitoring by the central zone temperature of infrared thermometer to heating zone, until the temperature monitored reaches between 730 ~ 750 DEG C simultaneously;
(4) carry out after continuous heating makes its surface temperature maintain 3 ~ 5 minutes between 730 ~ 750 DEG C with oxyacetylene torch neutral flame to flame shrinking district, air cooling.
Beneficial effect:
1, the present invention is by the experimental study to the system of going deep into of high weather resistance steel flame shrinking technology, inquired into various Heating temperature to the influence degree of weathering steel flame shrinking district structure and properties and rule filters out optimum flame heating schedule parameter and the type of cooling from the analysis of microtexture and salient features contrast, achieves comparatively satisfied technique effect.Experiment results proved: when adopting above-mentioned processing parameter to carry out flame shrinking to high weather resistance steel, the hardness of flame shrinking district mother metal and intensity are closest to mother metal.Correcting between the ferrite crystal grain in the microstructure of district's metal has apparent dispersoid particle to be distributed on crystal boundary.Thus the low-temperature impact work of district's metal is corrected higher than mother metal.When-40 DEG C of test temperatures, ballistic work A
kVreach 200J, for the highest computer heating control in rectification district is at the same material test specimen ballistic work A of 600 ~ 650 DEG C
kV2.5 times.
2, according to Flame Heating Temperature parameter range of application, infrared thermometer is demarcated, and determine that infrared thermometer corresponds to the emittance of 730 ~ 750 DEG C of temperature ranges thus, obviously improve the Surveying Actual Precision of workpiece surface temperature, the temperature in flame shrinking district can be strict controlled in 730 ~ 750 DEG C of temperature ranges, thus Heating temperature can be avoided to transfinite and cause mother metal penalty.
3, select oxyacetylene torch neutral flame to heat flame shrinking district, to compare with oxydizing flame with carbonizing flame and can not cause heating zone mother metal carburetting or decarburization.
4, adopt air cooling mode, by effectively suppressing the amount of precipitation of hardened structure, ferrite in rectification district mother metal being separated out on its crystal boundary with the fine-grannular tertiary cementite of disperse, and then obtains more tough microstructure and performance.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.
Fig. 1 is the flame shrinking district mother metal hardness curve of different heating normality condition.
Fig. 2 is the relation curve of infrared thermometer emittance by Experimental Calibration and workpiece surface temperature.
Fig. 3 is two groups of actual flame heating test specimen heating zone test thermal cycling curves of HT-856D high temperature modification infrared thermometer monitoring.
Fig. 4 is the flame shrinking district mother metal ballistic work-transition temperature curve of different heating normality condition.
Fig. 5 is the tertiary cementite stereoscan photograph corresponding to high weather resistance steel Dispersed precipitate on F crystal boundary under W3 line heating condition in Fig. 4.
Embodiment
As shown in Figure 1, import high weather resistance steel S355J2W is much more responsive to Flame Heating Temperature than ordinary low-carbon steel S355J2, and when maximum heating temperature is 800 DEG C, flame shrinking district mother metal hardness fall is 43%.Adopt flame shrinking once Flame Heating Temperature is selected improper or controlled improper, the mother metal penalty of flame heating zone will be made, serious use properties and the safety in operation reducing bogie frame.
The optimum flame heating schedule parameter of the demarcation of infrared thermometer and screening weathering steel flame shrinking district and type of cooling method as follows:
Heat treatment furnace is utilized to heat weathering steel by under setting heating schedule condition, under condition of different temperatures, utilize infrared thermometer to carry out temperature survey to weathering steel surface simultaneously, according to heat treatment furnace actual temperature adjustment infrared thermometer emittance, infrared thermometer displays temperature and heat treatment furnace actual temperature are coincide, obtain the relation curve of emittance and workpiece surface temperature, finally realize the demarcation of infrared thermometer.The different type of cooling is selected to cool to after weathering steel heating.Finally performance and metallographic detection are carried out to the weathering steel be disposed.
By the relation curve of the infrared thermometer emittance of Experimental Calibration and workpiece surface temperature as shown in Figure 2.From figure, the infrared thermometer emittance of differing temps testing conditions should strictly be programmed, otherwise will produce larger measuring error.And only provide the scope of steel emittance in infrared thermometer working instructions 0.78 ~ 0.82, and there is no corresponding relation chart that is clear and definite and detected temperatures.The emittance scope corresponding to temperature-measuring range of 300 ~ 800 DEG C that provide according to Fig. 2 is that 0.70 ~ 0.86 pair of infrared thermometer is demarcated, detect the data that obtain can with actual measurement workpiece surface temperature one_to_one corresponding, obviously can improve Surveying Actual Precision.
Utilize heat treatment furnace heat weathering steel under different heating normality condition and select the different types of cooling, then performance and metallographic detection are carried out to the weathering steel be disposed.Prove through a large amount of tests: heating and temperature control under 730 ~ 750 DEG C of processing condition, and cools in air cooling mode, and treated weathering steel has tough microstructure and performance.
Truck frame of high-speed motor train unit flame shrinking method of the present invention is specifically expressed as follows:
(1) select the infrared thermometer (such as HT-856D high temperature modification infrared thermometer) of suitable types, read over specification sheets, grasp using method and principle.Note determining that measuring distance should meet 30:1, the size of measured workpiece should be greater than 2 times of the area of detection of infrared thermometer.Then according to Flame Heating Temperature parameter range of application, infrared thermometer is demarcated, obtain the corresponding relation of infrared thermometer emittance and probe temperature, obtain 730 ~ 750 DEG C of corresponding emittance λ (as 0.84) according to emittance and the corresponding relation of probe temperature; Adjustment infrared thermometer makes its emittance equal λ; So that accurately detection and control heated condition.
(2) get out heated parts (weathering steel namely to be corrected), and on workpiece clear and definite heated perimeter (drawing weathering steel flame shrinking district profile), infrared thermometer is placed in above weathering steel flame shrinking district;
(3) with neutral oxygen acetylene torch, rectification district is heated, to avoid the scaling loss of mother metal carburetting or useful alloy element; In heat-processed, grilled gun should keep the homogeneous heating to correcting district, carries out Real-Time Monitoring with calibrated infrared thermometer to rectification zone center regional temperature simultaneously.When correct the maximum heating temperature in district reach temperature range that flame shrinking technique determines (730 ~ 750 DEG C, i.e. mother metal A
c1near) after, then maintain 2 ~ 3 minutes with grilled gun, to ensure to correct the process that there is an equalizing temperature in district.Then allow rectification district enter as air-cooled condition, allow workpiece carry out naturally cooling to room temperature.
The shape of flame heating zone according to the situation of correcting welding residual deformation, can adopt band shape, trilateral or point-like flexibly.
Experiment results proved: when adopting above-mentioned processing method to carry out flame shrinking, the hardness of flame shrinking district mother metal and intensity are closest to mother metal.As shown in Figure 3, adopt the thermal cycling curve of antidote correcting process of the present invention and ordinary low-carbon steel S355J2 thermal cycling curve to coincide very well, illustrates that to adopt the present invention to carry out thermal-stable to workpiece surface good, data are by force regular, genuine and believable.As shown in Figure 4, correct between the ferrite crystal grain in the microstructure of district's metal and have apparent dispersoid particle to be distributed on crystal boundary, thus correct the low-temperature impact work of district's metal higher than mother metal.Fig. 5 is the flame shrinking district mother metal ballistic work-transition temperature curve of different heating normality condition.-40 DEG C time, still close to 200J, not there is Transition of Brittleness in flame shrinking district mother metal ballistic work-transition temperature curve that in figure, W3 line characterizes, for rectification district maximum heating temperature controls the same material test specimen ballistic work A at 600 ~ 650 DEG C
kV2.5 times.
Technology key technical essential of the present invention:
Guarantee that flame shrinking district maximum heating temperature is strict controlled between 730 ~ 750 DEG C, prevent mother metal softening and brittle, to make sheet be distributed in after tertiary cementite absorbed, again redistribute on crystal boundary with the fine particulate of disperse.
Other correlation technique main points have:
Can not on same heating location repeatedly Repeat-heating;
Adopt air cooling mode, do not use water-cooled, prevent hardened structure;
Flame properties selects neutral flame, does not adopt carbonizing flame and oxydizing flame;
When without follow-up stress-removal thermal treatment, heating zone is not selected in the larger Tension Stress Zone of load.
(1) protection of district's Temperature monitoring technology is corrected
Industrial circle adopted tempilstick or thermocouple temperature measurement in the past.The former only can judge that whether Heating temperature exceedes a certain boundary value, can not realize the higher limit of continuous temperature measurement and virtual condition; Latter is not suitable for surface temperature measurement and flexible monitoring thermometric practical work piece being corrected to surface, district on a large scale.The far infrared temperature measurement of the utilization actual steel surface temperature calibration curve operation that the present invention releases then can upper control limit temperature, can be suitable for again the ground thermometric flexibly that has no mechanical damage of any position of workpiece surface.What must emphasize is exactly a bit: should strictly by Fig. 2 of the present invention illustrate demarcation the important program parameters of emittance curve to infrared thermometer---emittance is strictly programmed and is verified.Otherwise, the validity of temperature measurer can be affected, namely cause larger measuring error.
(2) protection of flame shrinking technology characteristics operation parameter
Flame shrinking technology in the past to the span of control of heating zone top temperature mostly between 600 ~ 700 DEG C; Do not allow in principle to exceed transformation temperature A1.The present invention then emphasizes that flame shrinking district top temperature must be strict controlled in the stated limit of temperature near AC1, namely between 730 ~ 750 DEG C; The hardness of now correcting district's mother metal declines minimum, and yield strength is basic consistent with mother metal, and low-temperature impact work is ideal, close to 200J.Its technique intension is exactly eliminate sheet 3 cementites in the original mother metal in flame shrinking district on ferrite grain boundaries with the heat-processed of flame shrinking; In the process of flame shrinking district mother metal air cooling subsequently, to make again in rectification district mother metal on ferrite grain boundaries granuliform 3 cementites of disperse educt again.And then obtain more tough microstructure and performance (see Fig. 4).
Claims (1)
1. a truck frame of high-speed motor train unit flame shrinking method, is characterized in that comprising the steps:
(1) according to Flame Heating Temperature parameter range of application, infrared thermometer is demarcated, obtain the corresponding relation of infrared thermometer emittance and probe temperature, obtain 730 ~ 750 DEG C of corresponding emittance λ according to emittance and the corresponding relation of probe temperature; Adjustment infrared thermometer makes its emittance equal λ;
(2) on workpiece, draw weathering steel flame shrinking district profile, infrared thermometer is placed in above weathering steel flame shrinking district;
(3) with oxyacetylene torch neutral flame, flame shrinking district is heated, carry out Real-Time Monitoring by the central zone temperature of infrared thermometer to heating zone, until the temperature monitored reaches between 730 ~ 750 DEG C simultaneously;
(4) carrying out continuous heating with oxyacetylene torch neutral flame to flame shrinking district makes its surface temperature exist
After maintaining 3 ~ 5 minutes between 730 ~ 750 DEG C, air cooling.。
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102605148A (en) * | 2012-04-05 | 2012-07-25 | 吉林大学 | Weathering steel flame straightening process |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102605148A (en) * | 2012-04-05 | 2012-07-25 | 吉林大学 | Weathering steel flame straightening process |
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Application publication date: 20150408 |