[雙語(yǔ)翻譯]熱沖壓外文翻譯--一種提高成形性和生產(chǎn)率的新型熱沖壓工藝的研究

1、2200 英文單詞， 英文單詞，1.2 萬(wàn)英文字符，中文 萬(wàn)英文字符，中文 3600 字文獻(xiàn)出處 文獻(xiàn)出處: Ganapathy M, Li N, Lin J, et al. Investigation of a new hot stamping process with improved formability and productivity[J]. Procedia engineering, 2017, 207: 771-776.

2、Investigation of a new hot stamping process with improved formability and productivityM. Ganapathy, N. Li, J. Lin, D. BhattacharjeeAbstractIn order to improve the drawability of boron steel and also to increase the produ

3、ctivity of hot stamping process, a new hot stamping process with pre-cooling has been proposed. Stress-strain behavior at various temperatures was investigated and compared with that in traditional hot stamping processes

4、. Detailed studies were carried out on the strain hardening parameter, n, at different temperatures and deformation rates. To evaluate this concept, hot stamping experiments were performed with both conventional (without

5、 pre-cooling) and new process (with pre-cooling) for a scaled down B-Pillar automotive component. The new hot stamping process with pre-cooling was able to produce the B-Pillar at low temperature (500 ℃) with less thinni

6、ng than the hot stamping carried out without precooling at high temperature (765 ℃). Also the in-die quenching time was reduced by about 60%, by adopting the new hot stamping process with pre-cooling, which would increas

7、e the productivity significantly for automotive mass production without compromising the part quality.Keywords: Hot stamping; Improved hot stamping; Boron steel; strain hardening.1. IntroductionA typical hot stamping pro

8、cess of a press hardening steel is described in Fig. 1(a). The process begins with steel containing ferrite and pearlite microstructure with tensile strength of approximately 600 MPa. The material is heated to above aust

9、enite temperature, usually about 900 ℃ and kept in furnace for a few minutes to get complete austenite phase. The austenized material blank is quickly transferred from the furnace to the stamping tool and deformed into t

10、he required shape with simultaneous rapid cooling within pressurized-closed-dies. It is necessary to achieve a faster cooling rate during cold-die quenching to ensure martensitic formation for post-form ultra-high streng

11、th product of approximately 1500 MPa [1].Currently the stamping temperature in conventional process is about 800 ℃. At this temperature, the material is softer and more ductile. However, high temperature also results in

12、materials with low strain hardening exponent (n- value). Materials with a lower n value have less drawability than those with high n values. Moreover, during hot stamping, it is necessary to achieve a faster cooling rate

13、 (> 27 ℃/s) during in-die quenching. It takes about 6-15 seconds to quench the material from 800 ℃ to 250 ℃ within a pressurized die depending on die pressure and the thickness of material blanks, which decreases the

14、productivity. Also the tooling cost is increased because of die cooling arrangements. The die temperature increases due to high stamping temperature of boron steel [2, 3], which results in a longer waiting period between

15、 the stamping strokes. The employed elevated temperature and relative movement between tool and blank lead to an increased wear rate of the tool reducing its lifetime [4].To overcome the above limitations, a new hot stam

16、ping process with intermediate cooling has been proposed [5, 6] as shown in Fig. 1(b). However, detailed investigation on the above supplied by the device for cooling the material. The cooling plate contains multiple noz

17、zles for uniform cooling. All the stages were computer controlled with closed loop feedback control system to ensure the heating temperature, pre-cooling time (or completion temperature of pre-cooling), transfer time and

18、 the starting of forming temperature to be accurately controlled. The feeder was able to pick, transfer and position the blank on the stamping tool within 8 seconds. Monitoring and control of temperature during transfer

19、and pre-cooling was done by a non-contact infrared pyrometer which was attached on the feeder as shown in Fig. 2a. The pyrometer was calibrated before the test with contact k-type thermocouples. The material was heated t

20、o 900° C and held for about 60 Seconds for homogenization and then transferred with the help of feeder to pre-cooling stage. To prevent the decarburization and scale formation, the heating was performed in nitrogen

21、atmosphere. The material was cooled to slightly above the required stamping temperature in 3 seconds, and then the austenized boron steel was quickly placed on the B-Pillar die. Stamping was done at a range of start temp

22、eratures (765 - 440 ℃) and at three different forming speeds (60, 150, and 350 mm/s). The variability of the process depends on the transfer time, pre-cooling rate and blank temperature at the beginning of stamping, henc

23、e the experiments were conducted with three samples for each of the process conditions to ensure repeatability of hot stamping process condition.Fig. 2. (a) Conventional stamping process; (b) Proposed stamping process wi

24、th pre-cooling.2.3. Quenching testsQuenching tests were done to evaluate quenching time during hot stamping operations. The quenching temperature was recorded for press hardening the boron steel at various temperatures w

25、ith different die temperatures and contact pressure. A circular boron steel blank with the diameter of 80 mm and the thickness of 1.5 mm was used as the test-piece. K-type thermocouples were embedded in the tool setup an

26、d work-piece at the locations as shown in Fig. 3. The dies were made from AISI H13 steel and were fixed on a hydraulic press machine with a maximum load capability of 25 tonne as shown in Fig. 3(a). Top and bottom die we

27、re heated using a band heater placed around the die periphery as shown in Fig. 3(b), which ensures uniform heating compared to other heating techniques [8]. In the quenching tests, the dies were pre-heated to different t