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When all the holes have been recognized, noncircular holes (if there are any) will be analyzed for semi-direct piloting. For this purpose, a circumscribing rectangle is created around the entire contour of each hole. If the dimensions of this rectangle are larger than a minimum allowance, then this hole may be a suitable hole for semi-direct piloting. So in the next step the software generates a circle with maximum possible diameter in the center of the rectangle. At the first iteration the diameter is equal to the width of the rectangle. If there is no intersec- tion between this circle and the edges of the hole, then the circle is perfect for semi-direct piloting. Of course the diame- ter of the actual pilot is less than this diameter because there should be an allowance between the circle and the edges of the hole which are supposed to be the final edges of product. But if there is an intersection between the circle and the edges of the hole, the circle is moved by an amount of X in rectan- gle length direction in both sides. The amount of X can be where l is the rectangle length; d is the diameter of the circle
which is considered as a semi-direct pilot; AX is displacement
domain of center of the circle in X direction when the circle is
still inside the rectangle.
If the circle intersects the rectangle, then it will also inter- sect the edges of the hole or it will be outside the hole. So
the center of the circle is moved by ıX to the right or left. In
this paper, ıX is taken to be 0.1 of X. However, like all other
variables, the user can input his own values. In each iteration,
the existence of an intersection is inspected. If a circle cannot be found without an intersection, then the diameter of the
circle will be reduced by ıd and the circle is positioned once
again in the center of the rectangle and the same procedure is
repeated. The calculations for ıd are shown in Eq. (14).
ıd = k(w dmin) (14)
where w is the width of the rectangle; dmin is minimum allow- able diameter of a pilot (dependent on strip and operation
parameters). k is the accuracy factor chosen to be 0.1 (can be altered by the user).
Reducing the diameter opens a displacement domain in Y direction. This domain can be calculated by Eq. (15).
AY = w d (15)
where AY is the displacement domain in Y direction.
So the center of the circle is moved in both X and Y direc-
tions. In this algorithm, the diameter of the circle diminishes gradually, and for each diameter all possible locations are checked.
When a location is recognized as a suitable place without any intersection, it is reasonable to say that this location is the best one because the circle in this position is the farthest away from the edges of the hole as shown in Fig. 9A. This is the exact position that an expert designer selects for semi-direct piloting. The smaller the diameter of the circle, the larger the displacement domain, as shown in Fig. 9B. Fig. 9C shows that 摘要：在现代化的工业中，金属板材是工业上最常见的零件之一。级进模在金属板材生产中具有的特殊作用。与此同时，在设计过程中，设计人员需要大量的时间和专业知识。二级进模设计中的一个重要活动是“嵌套”和“引导”。在此，本文介绍了一个相关设计的软件，它可以自动排料，并按照不同部位按以最小的废料来进行排样设计。此外该软件还具有选择最合适的现有的孔或设计对带钢的废料部分辅助孔控制的目的，大大减少了在设计中所需要的时间和精力。
毕业论文关键词：级进模、嵌套、引导
1介绍：
钣金材料产品经常用于工业中。冲压工具在钣金材料产品的设计中扮演着一个关键的角色。当有超过一个工序需要是必要的，级进模可以用来代替几个不同的模具。级进模的设计较为复杂，设计成本也较高，但是好的级进模设计可以用于大规模生产中。在级进模设计时需要设计人员有足够的专业知识，设计经验，以及在设计时应尽可能的减少废料，提高材料利用率。在钣金件生产中大约有百分之七十的生产费用用于材料上，所以提高材料利用率，降低生产成本在设计中至关重要。最近的几十年里，无论是在学术或者是工业生产中，自动化设计级进模已经有了很大的进步与应用。