外國工程師傳授的design資料.doc

外國工程師傳授的design資料，供大家享受。9s0l#ffb$Z KHInjection Molding Design Guidelines CAD/CAM/CAE综合资讯网站论坛i3xxIoM注塑模具设计指导0MBbt5L www.iCANu1mMuch has been written regarding design guidelines for injection molding. Yet, the design guidelines can be summed up in just a few design rules.已经有许多关于设计注塑模具的书了,但是设计准则可以被概括以下几点:U)J9L7CAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训iCAx开思论坛9m$|h9VAhUse uniform wall thicknesses throughout the part. This will minimize sinking, warping, residual stresses, and improve mold fill and cycle times. 1.零件整体壁厚保持均匀.这样可以最小化缩坑,翘曲,强度减小,模具填充和循环时间.Omqp1FzCAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训4Ln?dH%3dI,Use generous radius at all corners. The inside corner radius should be a minimum of one material thickness. 2.在转角处大量采用圆角.圆角内部最小半径为一个壁厚.(r8rY5b$J Ywww.iCA9J1S,n;WT unvx(5VUse the least thickness compliant with the process, material, or product design requirements. Using the least wall thickness for the process ensures rapid cooling, short cycle times, and minimum shot weight. All these result in the least possible part cost. www.iCA3G+d &W3.根据工艺,材料,产品设计需求.采用最小壁厚.最小壁厚的应用可以确保快速的冷却,短循环时间和减少喷射重量.所有这些最终达到最小的产品成本.2u4H8D(t:PV ZpeCAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训Design parts to facilitate easy withdrawal from the mold by providing draft (taper) in the direction of mold opening or closing. CAD/CAM/CAE综合资讯网站论坛4l6Z7v.V2jQ0G%4.在模具开合方向设置拔模角便于设备的运做.*P:r(Z yUse ribs or gussets to improve part stiffness in bending. This avoids the use of thick section to achieve the same, thereby saving on part weight, material costs, and cycle time costs.5.为了提高产品强度抵抗弯曲应该加筋或肋.避免用厚的结构达到同样的效果,以此减少了产品重量,材料成本,循环时间成本.The use of ribs iCAx开思论坛8o.y+p-p t*C筋的应用J9x4LbP#HRibs increase the bending stiffness of a part. Without ribs, the thickness has to be increased to increase the bending stiffness. Adding ribs increases the moment of inertia, which increases the bending stiffness. Bending stiffness = E (Youngs Modulus) x I (Moment of Inertia) 如果没有筋来增加强度,厚度就必须增加(费话一堆).加强筋增加了转动惯量!y%V-&dEgZswww.iCAl)OeCVCThe rib thickness should be less than the wall thickness-to keep sinking to a minimum. The thickness ranges from 40 to 60 % of the material thickness. In addition, the rib should be attached to the base with generous radiusing at the corners. 筋的厚度要单独的筋,为了防止在反面产生缩坑,尽量出去交叉中心的材料.v,3TIZ7SeP CAD/CAM/CAE综合资讯网站论坛W 9J&q3r+CW4C9W.&P+|%*X9nwww.iCAThe height of the rib should be limited to less than 3 x thickness. It is better to have multiple ribs to increase the bending stiffness than one high rib. EKqoL|/ 筋的高度自锁角.(记住公式就可以了)_&i,i_:P&i mHoLCiCAx开思论坛!P2_t2U!N1R;z2f1Bwww.iCAwhere is the coefficient of friction which ranges from 0.3 to 0.6 for most plastics. /u 摩擦系数就不说了.This computes to angles ranging from 73 for low coefficient of friction plastics to 59 for high coefficient of friction plastics. 高的摩擦系数表面的自锁角为59,小的为73If this angle is exceeded then the snaps will not pull apart unless the snap beam is deflected by some other means such as a release tool. (本段大意就是要大于自锁角)h9qV8l!l(k&pm3!This property can be used to advantage depending on the objective of using the snaps. If the snaps are to be used in the factory for assembly only (never to be disassembled by the end user), then the ramp angle the self-locking angle should be exceeded. If the user is expected to disassemble (to change batteries in a toy for example), then the angle should not be exceeded. 如果不要拆卸就设计自锁角,要是方便以后拆就自锁角。 Tooling for snaps is often expensive and long lead time due to 7fk4+Gn!X/MMFICAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训/mUjmz(mUCCAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训-The iterations required achieving the proper fit in terms of over travel. The amount of over travel is a design issue. This will control how easy it is to assemble, and how much the mated parts can rattle in assembly. This rattle can be minimized by reducing the over travel or designing in a preload to use the plastics elastic properties. However, plastics tend to creep under load, so preloading is to be avoided unless there is no other option.CAD,CAE,CAM,IOften, side action tooling (cam actuated) is required. This increases the mold costs and lead times.Cam actuated tooling can be avoided if bypass coring can be used that results in an opening in the part to allow the coring to form the step.;Pg4!p:_6hi6xwww.iCA大概就是说在模具设计时卡扣，要考虑用側抽，但是这样一来又会增加成本。所以尽量不用。（本人对模具术语不熟）Zo%kh2Z2/Z*e1v-hCmrCAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训 Some common problems of using snaps:mP1%VB4KlCAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训6m/I_c,!2Y-Too high a deflection causing plastic deformation (set) of the latch (the moving member). Care has to be taken that the latch does not take a set. Otherwise, the amount of latch engagement could reduce, reducing the force to disassemble. If the set is bad enough the engagement might even fail.大体就是说卡扣对模具公差要求高。很容易失效。eC4A9b V9?D f2n V7 CAD/CAM/CAE综合资讯网站论坛-The moving arm could break at the pivot point due to too high a bending stress. This can be avoided by adhering to the design principles and not exceed the yield strength of the material-in fact it should be kept well below the yield strength depending on the safety factor used. 移动臂在重心点由于抬高的弯曲力易折断。尽量考虑安全因素，可以避免。s_ zCAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训 Tt f6u+MVMn-Too much over travel leads to a sloppy fit between mating parts resulting in loose assemblies that can rattle. g3dyt$o*mu_ CAD/CAM/CAE综合资讯网站论坛 太多的过移动导致结构松散。(wI7zzNj*Q4|EY(H9b#lpwww.iCAx.cT0jh$canKwww.iCA Good snap design practicesZa y9s3 CAD/CAM/CAE综合资讯网站论坛 www.iCA#o+sm-Design the latch taking into account the maximum strain encountered at maximum deflection.jK5h:? x s:DL,q在大倾斜时考虑最大的应力。-In general, long latches are more forgiving of design errors than short latches for the same amount of deflection, because of the reduced bending strain. CAD/CAM/CAE综合资讯网站论坛0FG*FYjk一般地说，长臂比短臂更好，因为减少了应变。- Build mold tooling with tool safe condition. By this we mean that the deflection or over travel, or length of engagement can be changed easily by machining away mold tooling, rather than add material to mold tooling, which is more expensive and not good mold practice. This safe condition allows for a couple of tooling iterations of the latch, until the snap action is considered acceptable. Hookes Law(TrG9SXtSprings are fundamental mechanical components which form the basis of many mechanical systems. A spring can be defined to be an elastic member which exerts a resisting force when its shape is changed. Most springs are assumed linear and obey the Hookes Law, oaB0 W弹簧是组成众多机械零件中的基本部件。它在发生形变后产生力。大多数弹簧是线性的并遵守胡克定律。*O)M)B5y,MW,bR%E)xyT&DO3V1u/where F is the resisting force, D is the displacement, and the k is the spring constant. www.iCAe$I(p6x*EURI;u GF力，D位移，K弹性系数。.r$D Qe9O CAD/CAM/CAE综合资讯网站论坛For a non-linear spring, the resisting force is not linearly proportional to its displacement. Non-linear springs are not covered in depth here. 9jj(|lo8_/ZE6OCAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训 ;x&TT!cT!3S CAD/CAM/CAE综合资讯网站论坛 Basic Spring TypesiCAx开思论坛6E%j7g+tGBF3z)A4lok&S.n!FCAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训 &aC_CAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训Springs are of several types, the most plentiful of which are shown as follows, (|Qh P:Z2b&V*iO www.iCA9!eZrqd:T_9M弹簧分类eOzD0u4Llwww.iCACircular cross section springs are shown. If space is limited, such as with automotive valve springs, square cross section springs can be considered. If space is extremely limited and the load is high, Belleville washer springs can be considered. These springs are illustrated below, $_U78hO(h/L0Ai-C1ASj-oiCAx开思论坛f L*vAk?9MbQC3JCAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训Leaf springs, which are illustrated above in a typical wheeled-vehicle application, can be designed to have progressive spring rates. This non-linear spring constant is useful for vehicles which must operate with widely varying loads, such as trucks. CAD/CAM/CAE综合资讯网站论坛g6C*_+EK0COUDw)5J%Y1JKHistory of Springs|6lD%Kq|iCAx开思论坛 lB&bSS#IKii-PiCAx开思论坛Like most other fundamental mechanisms, metal springs have existed since the Bronze Age. Even before metals, wood was used as a flexible structural member in archery bows and military catapults. Precision springs first became a necessity during the Renaissance with the advent of accurate timepieces. The fourteenth century saw the development of precise clocks which revolutionized celestial navigation. World exploration and conquest by the European colonial powers continued to provide an impetus to the clockmakers science and art. Firearms were another area that pushed spring development. aPIa:XS:?iiCAx开思论坛The eighteenth century dawn of the industrial revolution raised the need for large, accurate, and inexpensive springs. Whereas clockmakers springs were often hand-made, now springs needed to be mass-produced from music wire and the like. Manufacturing methodologies were developed so that today springs are ubiquitous. Computer-controlled wire and sheet metal bending machines now allow custom springs to be tooled within weeks, although the throughput is not as high as that for dedicated machinery. O-Rings are torus-shaped (i.e. doughnut-shaped) objects made from elastomeric compounds such as natural or synthetic rubber, and are used to seal mechanical parts against fluid movement (air or liquid). O-Rings perform their sealing action by deforming to take the shape of their cavity, after being oversized to guarantee an predetermined interference fit. J b!x*E7 k+L j|+Y CAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训O-Rings are inserted into cavities defined as glands, and are typically used in one of two seal designs, axial or radial. These seal designs along with their gland geometries are shown in the following schematic: CAD/CAM/CAE综合资讯网站论坛j 0r(vcW,f%An O-Ring is specified by its inner diameter, its cross-section diameter, its material hardness/durometer (typically defined by the Shore A hardness), and its material composition. www.iCAe9m ? upkWnD5LIn order for an O-Ring to seal against the movement of fluid, it must be compressed when seated inside the gland. A standard set of design guidelines exist to determine the proper O-Ring dimensions for radial and axial seals of a given dimension. UHXw3y+HO-Ring Symbol Definitions L|U6p0| CAD/CAM/CAE综合资讯网站论坛 CAD/CAM/CAE综合资讯网站论坛8o%ae0Q2F7gXrJQW5NCAD,CAE,CAM,ICAX,idesign,模具,设计,招聘,培训Parameters used in the discussion of O-Rings are defined in the following table:fKaT1Hwww.iCAt+W Z ud:sXO-Ring Parameters J*f,tP/Y)a;Q1NSymbol Parameter Description 3z5F:Nar&dDwww.iCAID Inner Diameter Diameter of the inside edge of the cross-section. 8|,r8lU+s)v2Wwww.iCACSmax Maximum Cross-Section Diameter Upper bound on the cross-section diameter for a given set of input requirements. RrY7T%Ln_;V%E4KCSmin Minimum Cross-Section Diameter Lower bound on the cross-section diameter for a given set of input requirements. iCAx开思论坛jLcQ?S6&NrCStol Cross-S