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1、材料成型及控制工程专业毕业设计(论文)外文翻译 中文2500字 本科毕业设计翻译 学生姓名：* 班级：*班 学号：* 学院：材料科学与工程学院 专业：材料成型及控制工程 指导教师：* 副教授 2022年3月25日 Section 4 Die Design and Construction Guidelines for HSS Dies General Guidelines for Die Design and Construction Draw Dies Higher than normal binder pressure and press tonnage is necessary with
2、 H.S.S. in order to maintain process control and to minimize buckles on the binder. Dies must be designed for proper press type and size. In some cases, a double action press or hydraulic press cushion may be required toachieve the necessary binder forces and control. Air cushions or nitrogen cylind
3、ers may not provide the required force for setting of draw beads or maintaining binder closure if H.S.S. is of higher strength or thickness. Draw beads for H.S.S. should not extend around corners of the draw die. This will result in locking out the metal flow and cause splitting in corners of stampi
4、ng. D raw beads should “run out” at the tangent of the corner radius to minimize metal compression in corners, as shown in figure 16 on page 47. Better grades of die material may be necessary depending on the characteristics of the HSS, the severity of the part geometry, and the production volume. A
5、 draw die surface treatment, such as chrome plating, may be recommended for outer panel applications. Form and Flange Dies Part setup in form and flange dies must allow for proper overbend on all flanges for springback compensation. Springback allowance must be increased as material strength increas
6、es; 3 degrees for mild steels, but 6 degrees or more for HSS. Punch radii must be fairly sharp. 1t for lower strength steels. Higher strength steels may require larger radii, but keeping them as small as practical will reduce springback in the sidewalls. Flange steel die clearance must be held to no
7、 more than one metal thickness clearance to reduce springback and sidewall curl. Form and flange steels should be keyed or pocketed in the casting to avoid flexing. Flange steels should be designed to wrap over and coin the flange break in order to set the break and reduce springback. See figure 17
8、on page 48. Die strength must not be compromised with light-weight die construction. High strength steel will require a stiffer die to resist flexing and the resultant part distortions, especially for channel or “hat-section” parts. This type of part can also cause serious die damage if double blank
9、s occur. Cutting Dies To reduce press tonnage requirements and extend die life, a minimum shear of four to six times metal thickness in twelve inches of trim steel length is recommended. To reduce die maintenance, maximum trim angles should be about 5 to 10less than those used for mild steel. Trim s
10、teels should be keyed or pocketed in casting to avoid flexing. Die clearance should be 7 to 10% of metal thickness. Drawbead Types Conventional Drawbeads Run-out Drawbeads For H.S.S. Lock Beads for Stretch-Form Die Figure 16 1. Providing a vertical step in the flange stiffens and straightens the fla
11、nge, stopping sidewall curl as well as springback. 2. The addition of stiffening darts helps maintain a 90-degree flange. 3. By adding a horizontal step along the flange, the flange is stiffened, resulting in reduced springback. 4. Back relief on the upper flange steel allows for extra pressure to b
12、e applied futher out on the formed radius. Section 5 Die Tryout Guidelines for High Strength Steel Dies General Guidelines for Die Tryout Draw Dies Higher draw die binder pressure and press tonnage will be necessary in order to maintain process control and draw parts without buckles. A double action
13、 press or a press with hydraulic cushion may be required in some cases to achieve the required binder forces. HSS draw die operations will require sheet steel lubricants that are formulated for extreme pressures. Mill oils will not provide sufficient lubricity for most applications. Pre-lubes or dry
14、 film lubricants may be necessary for process control. Die plan view punchline corner radii should be larger than with mild steels to avoid buckling in the corners of the binder. Stretch Form Dies Lock beads may require modification to avoid cracking or tearing with higher strength grades of HSS. Op
15、ening side walls of beads and enlarging corner radii will avoid cracking of high strength sheet steel. Lock beads should be continuous around the punchline for stretch form dies. For large panels from stretch-form dies, such as a roof panel or hood outer, elastic recovery may result in a shrunken pa
16、nel that does not fit well on the male die member of the trim or flange dies. This problem is corrected by adding a “plus” factor to the overall part dimensions of the draw die or stretc h form die punch. This “plus” is usually no more than 2.5 mm at the center of the sides and the front, tapering t
17、o 0.0mm at the corners of the part profile on the punch. Finish part profile is defined, and plus is removed, in the main flange die. Form and Flange Dies The punch radius should be fairly sharp with 1 or 2t used for lower strength steel. HSS may require larger radii, but as small as practical to re
18、duce springback of sidewalls. The flange steel radius affects sidewall curl and springback on any offset flanges. This radius should also be small to reduce springback of side flanges. Overbend for springback compensation must be increased as tensile strength increases: 3 degrees is standard for mil
19、d steels, but 6 degrees or more will be required for HSS. Flange steel die clearance should be tight, maintaining no more than one metal thickness clearance to reduce springback and sidewall curl. Cutting Dies To reduce press tonnage requirements and extend die life, a minimum shear of four to six t
20、imes metal thickness in twelve inches of trim steel length is required. Die clearance should be 7 to 10% of metal thickness for HSS. To reduce trim steel maintenance, reduce maximum trim angles by about 5 to 10 from those used for mild steel. Trim steels should be keyed or pocketed in the casting to
21、 avoid flexing. Die Tryout When Using Bake Hardenable Steel In order to obtain the maximum benefits of BHS, tryout of the dies should be performed as follows: Circle grid analysis must be performed on a panel before any die rework is attempted. With the gridded panel as a reference, the die can be m
22、odified to provide a minimum biaxial stretch of 2.0%. Stretch-form or draw dies are best for this material. For rough or functional tryout, it is possible to use mild steel with a 6% to 8% gauge increase to perform the normal process of die preparation. This alleviates complications when the BHS str
23、engthens between each die being tried out. The reason for this is the time lag that normally occurs between a panel being formed and its use in the next operation. When the entire line of dies is ready for approval, all dies must be set in line. Panels should be run through all the die operations co
24、nsecutively. This will avoid some of the strengthening effects of time delays between stamping operations that can cause variation in panels. Dimensional approval of the panel will be most difficult if this procedure is not followed. The strengthening reaction in the BHS can cause dimensional variat
25、ion in flanges since springback will vary with time as the strength increases. This is why running the panel through all die operations consecutively is crucial to a successful buyoff. Part Buyoff To reduce the part buyoff time and eliminate many hours of tryout time, the benefits of functional buil
26、d must be considered. This procedure has been proven to save time and money by concentrating on an acceptable sub-assembly rather than making each stamping to part specifications. Those parts that are easiest to change are revised to suit the sub-assembly dimensional targets. Those parts that do not
27、 affect the sub-assembly quality are not changed, but the detail part specifications are revised. The functional build process will eliminate excessive tryout hours if used for part buyoff on HSS stampings. In addition to saving tryout time and die rework costs with functional build, lower part vari
28、ation can also be realized. Two dimensional challenges faced by the die maker when first trying out dies are to reduce the dimensional variation from nominal specifications, and to reduce the short term variation from part to part. The typical priority is to first minimize part-to-part variation and
29、 later address nominal deviation. A strong argument for this strategy is that the deviation from nominal is not precisely known until a dimensionally consistent part can be evaluated. The results are a dimensionally consistent part even though a number of checkpoints may deviate from nominal, and pe
30、rhaps even be out of tolerance. In many situations when dimensions on the die are reworked to shift them closer to nominal, they become less stable and result in higher part-to-part variation. The functional build philosophy evaluates the acceptability of the part after it becomes stable, and before
31、 minor dimensional shifts are made. Large deviant or critical dimensions may be identified for rework even with functional build. There are dimensions that can often be spared rework based on a functional build approach. In these cases, the part remains more stable and the die more robust because le
32、ss rework occurs while attempting to shift dimensions. For more information on functional build, refer to the Auto/Steel Partnership publication. “Event-Based Functional Build: An Integrated Approach to Body Development”. 第四节-高强度钢模具设计和制造指南 对模具设计和制造的一般准则 拉深模具 为了控制高强度钢的成形并减少板料边缘的弯曲，高强度钢成型时的压力和吨位高于一般情况
33、是必要的。模具设计必须考虑适当的压力类型和尺寸。在某些情况下，为了达到需要的压边力和控制力可以用一种双动压力垫或液压垫。如果高强度钢有更高的强度和厚度，空气垫子或氮气缸可能提供不了固定拉深筋或保持边缘固定的力。 高强度钢拉深筋不应该在拉伸模具的转角处延长，这将会导致金属流动被锁定和在冲压件角落处产生开裂。拉深筋应该“远离”转角半径切线以减小金属在转角处压缩,如图16。 基于高强度钢的特性、重要部位的几何结构和生产量，选用好的材料制造模具是必要的。拉深模的表面处理,例如电镀，可推荐用于外板的应用。 胀形和翻边模 为了能补偿回弹量，用胀形和翻边模生产的零件必须允许适当的过度弯曲。回弹极限必须随材料强度增加而增加;3度适用于低度钢,但6度或以上适用于高强度钢。 冲床半径必须相当尖锐。低强度钢1吨位。高强度钢可以要求更大半径,但使保持和实际生产时一样小，可以降低侧壁的回弹。 翻边模具间隙必须不超过一个金属厚度间隙以降低回弹及侧壁发生