1. 제7장 판재성형가공 (1)

2. Topic: 자동차부품의 성형

4. Q: 판재성형시에 소재는 주로 어떤 변형을 받는가?
전단(shearing)
굽힘(bending)
신장(stretching)

7. <판재성형에 사용되는 프레스>

9. Topic: 판재 이론-네킹
체적일정
등방성인 경우

10. 변형경화지수 n 변형률속도 민감지수 m n, m 이 크면 총연신량 증가 네킹시작 e =n (s = Ke n 일 때)
네킹 이후에는 네킹부위의 변형률속도 큼
m 이 크면 네킹확산 (이차 연신)
n, m 이 크면 총연신량 증가

11. Topic: 판재이론-굽힘과 스프링백
Spring-back

12. Negative Springback
FIGURE Schematic illustration of the stages in bending round wire in a V-die. This type of bending can lead to negative springback, which does not occur in air bending (shown in Fig. 7.24a). Source: After K.S. Turke and S. Kalpakjian.

13. Springback Compensation
FIGURE Methods of reducing or eliminating springback in bending operations. Source: After V. Cupka, T. Nakagawa, and H. Tyamoto.

14. 최소굽힘반경

15. Bending Mechanics
FIGURE (a) and (b) The effect of elongated inclusions (stringers) on cracking in sheets as a function of the direction of bending with respect to the original rolling direction. This example shows the importance of orienting parts cut from sheet to maximize bendability. (c) Cracks on the outer radius of an aluminum strip bent to an angle of 90°; compare this part with that shown in (a).
FIGURE The effect of length of bend and edge condition on the ratio of bend radius to thickness for 7075-T aluminum sheet. Source: After G. Sachs and G. Espey.

16. Topic: 판재이론-이방성
R값의 정의
압연방향 고려시 평균값
평면이방성
Q: R 값이 크면 성형성이 향상되는가?

17. <귀생김(earing)>
Q: 귀생김의 정도를 예측할 수 있는 변수는?

18. Topic: 판재성형가공의 종류 기본공정 성형공정 회전성형: 스피닝(spinning, flow forming)
전단(shearing): 블랭킹
굽힘(bending)
신장성형(stretch forming)
성형공정
디프드로잉(deep drawing)
스템핑(stamping)
고무성형
액압성형(hydroforming)
회전성형: 스피닝(spinning, flow forming)
연속성형: 롤포밍(roll forming)
특수성형
고에너지속도 성형(HERF) (폭발성형)
초소성성형

19. Topic: 전단
shearing
blanking

20. Fine Blanking
FIGURE 7.9 (a) Comparison of sheared edges by conventional (left) and fine-blanking (right) techniques. (b) Schematic illustration of a setup for fine blanking.

21. Rotary Shearing
FIGURE 7.10 Slitting with rotary blades, a process similar to opening cans.

22. Shaving & Beveled Tooling
FIGURE Schematic illustration of shaving on a sheared edge. (a) Shaving a sheared edge. (b) Shearing and shaving combined in one punch stroke.
FIGURE Examples of the use of shear angles on punches and dies. Compare these designs with that for a common paper punch.

23. Progressive Die
FIGURE (a) Schematic illustration of producing a washer in a progressive die. (b) Forming of the top piece of a common aerosol spray can in a progressive die. Note that the part is attached to the strip until the last operation is completed.

24. Tailor-Welded Blanks
FIGURE Examples of laser-welded and stamped automotive body components. Source: After M. Geiger and T. Nakagawa.

25. Press Brake Operations
FIGURE (a) through (e) Schematic illustrations of various bending operations in a press brake. (f) Schematic illustration of a press brake. Source: Courtesy of Verson Allsteel Company.

26. Bending Operations FIGURE 7.24 Examples of various bending operations.
FIGURE (a) Bead forming with a single die. (b)-(d) Bead forming with two dies in a press brake.

27. Topic: 스피닝

28. Spinning
FIGURE Typical shapes produced by the conventional spinning process. Circular marks on the external surfaces of components usually indicate that the parts have been made by spinning, such as aluminum kitchen utensils and light reflectors.
FIGURE Schematic illustration of spinning processes: (a) conventional spinning, and (b) shear spinning. Note that in shear spinning, the diameter of the spun part, unlike in conventional spinning, is the same as that of the blank. The quantity f is the feed (in mm/rev or in./rev).

29. Shear Spinning
FIGURE Schematic illustration of a shear spinnability test. Note that as the roller advances, the spun part thickness is reduced. The reduction in thickness at fracture is called the maximum spinning reduction per pass. Source: After R.L. Kegg.
FIGURE Experimental data showing the relationship between maximum spinning reduction per pass and the tensile reduction of area of the original material. See also Fig Source: S. Kalpakjian.

30. Tube Spinning
FIGURE Examples of (a) external and (b) internal tube spinning, and the process variables involved.

31. Incremental Sheet-Metal Forming
FIGURE (a) Illustration of an incremental forming operation. Note that no mandrel is used, and that the final part shape depends on the path of the rotating tool. (b) An automotive headlight reflector produced through CNC incremental forming. Note that the part does not have to be axisymmetric. Source: After J. Jesweit.

36. <flow forming>

37. Topic: 롤 포밍

38. Topic: 튜브벤딩

40. Topic: 스템핑(stamping)
Progressive die

41. Topic: 폭발성형

42. Electrohydraulic and Magnetic-Pulse Forming
FIGURE Schematic illustration of the electrohydraulic forming process.
FIGURE (a) Schematic illustration of the magnetic-pulse forming process. The part is formed without physical contact with any object, and (b) aluminum tube collapsed over a hexagonal plug by the magnetic-pulse forming process.

43. Superplastic Forming
FIGURE Two types of structures made by combining diffusion bonding and superplastic forming of sheet metal. Such structures have a high stiffness-to-weight ratio. Source: Rockwell Automation, Inc.

44. Honeycomb Structures
FIGURE Methods of making honeycomb structures: (a) expansion process, and (b) corrugation process; (c) assembling a honeycomb structure into a laminate.

45. Topic: 디프드로잉

46. 문제: 알루미늄 1100-O 금속 판재를 인장시험하여 길이방향으로 23% 늘렸을 때, 두께가 10% 감소하였다
문제: 알루미늄 1100-O 금속 판재를 인장시험하여 길이방향으로 23% 늘렸을 때, 두께가 10% 감소하였다. 이 금속판재로 직경이 100mm인 원형블랭크를 일회의 공정으로 디프드로잉하여 얻을 수 있는 컵 중에서 직경이 최소인 컵의 직경을 구하여라.

49. <소재의 변형>
벽 부분
플랜지 부분

50. <블랭크홀더와 드로비드의 역할>

51. <디프드로잉 한계> 한계드로잉비 = Q: LDR = 2 일 때, 컵의 최대높이는?

52. 이방성의 효과
FIGURE Effect of grain size on the average normal anisotropy for various low-carbon steels. Source: After D.J. Blickwede.
FIGURE Effect of average normal anisotropy, R on limiting drawing ratio (LDR) for a variety of sheet metals. Source: After M. Atkinson.
FIGURE Typical earing in a drawn steel cup, caused by the planar anisotropy of the sheet metal.

53. Punch Force
FIGURE 7.59 (a) Die corner radius too small; typically, it should be 5 to 10 times the sheet thickness. (b) Punch corner radius too small. Because friction between the cup and the punch aids in the drawing operation, excessive lubrication of the punch is detrimental to drawability.

54. <재드로잉>
재드로잉
Q: 재드로잉의 원리는 무엇인가?

55. 다이
<디프드로잉의 해석> 소재
(블랭크)
블랭크홀더 쿠션 펀치