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RED CD Blanking is the use of molds to produce separate sheet stamping processes subjects, including blanking and punching. It can be made into parts, but also for the bending, drawing, forming and other processes to prepare rough. Washed down from the Board Division on the shape of the parts required (or rough) called off the branches. The shape of the workpiece out of the hole required (red to go to waste) is called punching. Figure I-1 of the washer, from falling branches and punching two processes to complete. Production practice, we die blanking process of a certain understanding of the structure, but perceptual knowledge to rational knowledge up to truly understand the nature of the blanking process, a better design of the development process and die. The following deformation on the blanking process, the quality of stamping parts, stamping die design and stamping die size blade structural design issues discussed. . Shown in Figure 1-2 blanking by the deformation process can be seen that the composition of the punch and the upper and lower concave edge chess, material on the concave mold, punch the material deformation gradually decreased until the completion of all the separate blanking. With the punch of the external forces acting on material changes in the number of the material on the external force changes in quantity, material deformation within the continuous development. The deformation of the blanking process is divided into three stages 1, elastic deformation stage Punch contact with material force as the punch pressure, the material is elastic compression and bending, and squeeze into the die hole. Then the stress does not exceed the material yield limit, if the punch relief, material or restitution, so that elastic deformation stage. 2, plastic deformation Punch to pressure, the stress reaches the yield limit of material, some metal is squeezed into the die hole, producing plastic shear deformation, are shining maggot cut surface. For convex, concave feel there is room between the depression, it is the plastic shear deformation is also accompanied by the bending and stretching. 3, fault isolation stage Materials continue to increase external and internal stress increasing, convex, because the incision die stress concentration, shear strength over the first internal stress, micro-crack appears. Mold continuing under pressure, convex, concave mold cavities of the micro-crack edge to the material constantly within the share capital, then pulled off material separation. Such as convex, concave die gap was reasonable, the upper and lower crack coincide with each other. Stress and strain Further analysis of blanking time of stress and strain state of deformation zone and help to the understanding of the blanking process. Die and punch in the edge of the joint line to take cell body, whose stress-strain diagram shown in Figure 1-3. Can be seen from the figure, it seems Metal fracture line AB that is cutting edge on-line) at 45 degrees. The main uranium direction I was pulling stress and tensile deformation, tensile stress the gold Is a fiber elongation; its vertical axis 2 is the compression stress direction and compressive deformation, the fiber extrusion pressure; in the tangential direction of the stress and strain is very small, negligible; and principal stress direction at 45. Direction to the direction of maximum shear stress between the punch and die clearance, elongation and tear off the metal, resulting in broken fracture surface roughness, and with a burr. The process can also blanking blanking force deformation curves of the figure is confirmed. Figure 2-9 (materials), is punching a 3 mm thick material punching power and punch of the curve. Can be seen from the diagram: In the process of blanking blanking force size is constantly changing. AB section of the equivalent of punching the elastic deformation stage, BC Section for the plastic deformation stage. When the material internal stress to shear strength began to crack when the material, CD segment for the crack propagation until the material isolated rupture in order teams, DE Dan launch materials introduced die mouth piece. The deformation process of blanking the red plant parts are not smooth vertical section, the section has three areas, namely, with rounded corners, bright band and the fault zone. Rounded band is in the process of blanking the beginning of plastic deformation. Since the bending and stretching metal fibers formed, soft material than hard Branch rounded large. Light zone is the second phase of deformation produced plastic shear deformation of metal forming, has a smooth vertical surface, bright band of the entire cross section of 1 / 2 to 1 / 3 of the light bandwidth of soft materials, hard materials with a narrow bright . With the mechanical properties of materials, space, mold structural changes. Fault is equivalent to the third stage of the blanking process, mainly due to the role of tensile stress, the continuous expansion of China cracks down payments second fiber extension, so a very rough surface is not smooth, and there Liaoduo. In the section on the same punch with these characteristics, but the distribution of the three regions opposite position and blanking. Blanking addition to drag a section of rough dimensions, there are points dome curved, not flat, face a burr, so blanking requirements apply only to an Blanking. Section Drawing gap Blanking time requires not only the shape of call times out of line drawing parts, there should be a certain quality requirements, quality of stamping pieces is cut surface quality, dimensional accuracy and form error. Cut surface should be flat, smooth, no crack and tear, mezzanine and other defects, glitches small parts, the surface should be flat as possible, that is a small vaulted arch, size, degree of precision required to ensure the drawings do not exceed the tolerance range. Factors that affect the quality of stamping pieces range from the actual production that, convex, concave die gap size and power uniformity, pattern edge state, the mold structure and manufacturing precision, quality materials, and so on all affect Na blanking. However, we must find out which plays a decisive role in the quality of the blanking factor. Gap is a. Section 1 on the quality of blanking Comparison of straight, smooth, and no burr. In this case, the quality of parts that is a good cross section. When the gap is too hours of up and down the crack does not coincide with each other. . . . When the gap is too large cracks do not overlap. . . . (See 2-11) If the gap uneven distribution of local spikes. . . Uneven wear, increased, so clearance is not only to use reasonable and die on the manufacture and adjustment of space even when the guarantee. 2. Gap on the Dimensional Accuracy Blanking Stamping dimensional accuracy refers to the actual size and nominal size of the margin, the difference is smaller the higher the precision. difference between living in two areas packet error, one blanking punch or die with the size of the deviation, one mold itself create bias. Blanking and convex, die size deviation was mainly due to: Workpiece (waste) from the concave mold release, as caused by elastic recovery. Deviation may be positive, it could be negative. Factors affecting the value of this deviation are: 1, convex, concave mold gap. Big gap. . . Tensile obvious effect, elastic recovery materials and parts to drop less than the die size, punching pieces. . Small gap. . . 2, material properties. Material properties and dimensional accuracy of packages since it will then determine the material properties of its material form in the amount of blanking. Outline of the elastic deformation of the soft small amount of elastic recovery after blanking also small, so the workpiece accuracy. Hard steel elastic recovery greater precision on the lower parts. 3, workpiece shape and size. Workpiece thickness and shape of post degree only-J also have an impact, thin elastic recovery of material punching shield large,-t pieces of low accuracy. The more complex the shape of the workpiece, die and create and adjust the gap when the more difficult to ensure uniform, so the greater the size of deviations. 4. Blade-like quality video straight to the section noon 5. Gap on the impact of blanking force The smaller the gap, blanking deformation area of the higher hydrostatic pressure, the greater the material change Kang force. Blanking force, the greater the contrary, when the gap increases, lower resistance, blanking force also decreases, but the value is not reduced (see Figure 2-14) Life on the sidelines of the impact of mold (see materials abbreviated talk) Section III to determine clearance punch and die Thus, convex and concave clearance on blanking die quality morning, punching power, tool life has a great impact, so the mold design - will select a reasonable gap to ensure Blanking section of good quality punching required is small, high-die life. But the difference of quality, precision, blanking force requirements in many aspects of cooperation were identified gap is not limited to the same - a value, but close to each other, taking into account the deviation of model county manufacturing and use of wear and tear, Therefore, production is often to select an appropriate range of reasonable space, as long as the gap falls within this range can be out of good parts, the scope of the minimum value, said minimum clearance Zmin reasonably small. Most reasonable position that the biggest gap Zmax. At least a reasonable gap Z Mi n can be with the board perpendicular to the section, without a significant glitch. In the largest gap Zmax section can still be satisfied with the quality: just not with the board vertical. Taking into account the die wear and tear during use to increase the gap, so when the design and manufacture a new model to use the smallest reasonable space Zmin Reasonable methods to determine gap calculated with the experience to determine and French. One theory to define the law Theory to define the main basis for the law is to ensure that cracks coincide in order to get a good cross section. Group 1 began the process of blanking the instantaneous crack q triangles from the graph we can find space z AB c Type in: A, - convex molded into the depth; - the maximum shear stress direction and the angle between the vertical; Can be seen from the above formula, gap z and the material thickness t, the relative cut into the depth h. / T and the crack orientation day. Relevant, but to another with the material properties and is related to the more rigid material, h. / T smaller. Therefore, we can see from the style, the main factors affecting the value gap is the material properties and thickness. The more rigid material more thick, the necessary and reasonable value of the larger gap. Table 1-3 for the popular press materials, h. / T and approximation. A variety of materials h. / T and value is still no accurate determination of value, and. Production is not convenient to use this method, so widely used empirical formula with the graph method. Second, the experience to determine methods Experience to determine the nature of law is based on the material and thickness, press-type to determine The formula: K-factor related with the material properties.t - thickness of material. Soft materials such as 08, l0, brass, copper Z = (0.08-0.1) t In hardwood Section: A3, A 4,20,25. Z = (0.1-0.I 2) t Hard materials such as A5, 50 . . and so Z = (0.1-0.14) t Lower limit of thin materials which take. Third, the chart method In addition, you can directly determine the space look-up table values (such as teaching materials 2-3,2-4,2-5 table) Table 2-5 is the former Ministry of Machinery Industry, blanking clearance, Technical Guidance Document (JB/z271-86 ) recommended clearance value. Over the past Chinas general information on using Soviet gap value, from the use of the experience, the gap value is generally small. One reason for this is the classification space is not used according to the characteristics of production, the other is only as the main basis for precision stamping parts, without considering the King and the chess section with a life of quality and other important factors, so many problems exist in production. For example: Wear + blanking force. . . Therefore, in practice, in addition to special requirements of the workpiece outside the vertical section, as far as possible large gap. In addition, my experience in practice should: (1) z-punching to take the value of bigger than expected drop. (2) red holes get bigger when the z value, to prevent broken punch. (3) Carbide Die z value should be 30% larger than the steel. (4)J die orifice is cone-shaped than straight smaller z value. (5) high-speed stamping dies easily when the heat, f value should get bigger. (6) when the punch and die wall thin. To prevent cracking up, should be enlarged punching z. IV Size Calculation of Cutting Edge Die edge dimensions and tolerances directly affect the dimensional accuracyBlanking, also is sufficient to guarantee a reasonable gap. Therefore, the correct calculation of the mold edge mold design dimensions and tolerances are small - the work of great importance. Dimensions and tolerances in calculating the cutting edge should follow the following principles: 1. Taking into account the drop size depends on the materials and parts die size, while punching pieces depends on the size of the punch dimensions of the blanking die design should be to die as the base is difficult to stay in the punch on the gap; Design Punching model should be based on the punch as the base, orange on the gap left in the concave. (There is a taper section, and the big end blanking parts die size = size, empty pieces of red punch small end size = size) 2. Taking into account the wear and tear will foot a larger die, the punch size decreases, in order to ensure the life of mold, the basic blanking die size should be taken close to or equal to the minimum limit of size of the workpiece; Piercing Punch basic dimensions shall be taken as close to the or equal to the maximum limit of size of workpiece, using the smallest reasonable gap value. 3. Sampling edge of manufacturing tolerances, the workpiece should be to ensure the accuracy and timeliness based clearance requirements. At the same time easy to mold manufacturing tolerance is too large, then out of the parts may be disqualified, or one can guarantee a reasonable gap; too small. And to die is difficult to mold manufacturing costs. Accuracy and precision blanking dies relationship table Special Note: If the size of the workpiece is not marked tolerance. I T14 without tolerances according to class to deal with, and die according to I D 11 manufacturing (non-graphic parts). Or by I T 6-7 class manufacturing (for round parts). Mold processing method according to the different calculation methods are divided into two kinds of edge 1. Separate punch and die machining Separate processing: refers to the punch and die are processed separately by the respective drawings, mold the size of the gap processed by guarantee. Therefore, to calculate and mark out the punch and die dimensions and tolerances. This method is suitable for round or shape of a simple piece. (1) Blanking Die Blanking piece size based degree d, according to the above principles, first determine the small scale and then reduce the die size in order to ensure a reasonable punch clearance. Knife-edge part of the incidence graph of the size shown. Edge blanking die size is calculated as follows: (2) The punching die set punching size of d. (Standard tolerance) calculated according to the principles of the punch first determine the size. Further increasing the die size in order to ensure a reasonable minimum edge clearance associated with some of the dimensions in Figure 2-13 (b) below. Red edge aperture size is calculated as follows: Symbol meaning: X-tolerance zone offset factor, the purpose is to avoid all bias limit most blanking size (other omitted) Its value and accuracy of the workpiece. Tolerance band offset coefficient of 2-7 x to be investigated, or obtained by the following relations Workpiece accuracy of IT10 above: x = 1 Workpiece accuracy of IT11 13: x = 1.75 Fine piece head IT14: x = 0.5 In order to ensure a reasonable space, mold manufacturing tolerances must meet the following conditions Convex, concave mold separate processing advantages are: convex, concave mold with interchangeable, easy to mold batch processing. Convex, concave mold separate processing disadvantage: in order to ensure a reasonable gap. Require higher levels of mold manufacturing tolerances, mold making more difficult. (Based on the use of examples to explain -6,2-7 table) 2. Punch and die with the processing For complex shapes or thin material workpiece. In order to facilitate mold, should be used with the process. This method is first processed basis documents (when blanking die, punch when the punch), and then base the actual size of the Huai items to do with the other documents (when blanking punch, punch when punch), and then base the actual size of the Huai items to do with the other documents (when blanking punch, punch die when), in another space on the revised smallest reasonable value. Therefore, when used with the process, simply reference documents marked size and tolerance, another mark only basic dimensions. And marked punch-foot small scale only by the actual preparation of the die to ensure the single gap (blanking time); or die size of the actual size of the preparation by the punch to ensure the side gap. (When punching ). With the process, the base parts of the manufacturing tolerance 6f (or long) is no longer limited by the gap value, or even appropriate to enlarge manufacturing tolerances, so relatively easy to manufacture molds. Most factories have recently used this combined approach. Benchmark parts manufacturing tolerances generally preferable to A / 4 For some the shape of complex stamping parts. For each part of the size of the different nature of the wear law is different, it must be a specific analysis. Calculated separately. Figure 2-20a for the blanking parts and die size ,2-20b for the punching pieces and punch size, in these two diagrams: A class size is worn larger size, such size should be charged formula feed die size (2 2) calculation, B Class size is worn by people of such small size scale should be punching punch size formula (2-4) calculation; C Class size is worn the same size, of such size, the size of the workpiece in the middle of the basic dimensions as the mold, and then standard deviation can be symmetrical, the specific formula as follows: V blanking force Cutting edge technology, including separation of materials needed for punching power and discharge power, pushing pieces of power and top pieces of power. After blanking. Washed down the workpiece (or waste) as elastic recovery and expansion will be within the infarct in the die hole. Similarly, the scrap piece or out of the hole on the elastic contraction because of tight coupling on the punch. ? Called the discharge power;? Named top material (pieces) force;? Called push material (pieces of) force. The purpose of calculating power stamping process is it? Reasonable choice is to press tonnage. (Of course choose not to consider the tonnage presses, as well as tables, press structure. Shut height, etc.) Select press when you press and public pressure (N) must make a big or equal to the total pressure during blanking First, the calculation of punching force Flat blade used in production Die Blanking, the blanking force can be calculated as follows; K-safety factor, and generally the skin = 1.3. It takes into account mold edge wear and blunting the punch and the die gap is uneven material thickness deviation of the performance factors, such as Ko. Blanking of high strength material or thick material and large size parts, the need to force a larger punch. If the blanking press more than the tonnage of the existing plant, it is necessary to reduce the blanking force. 1. Heating blanking Material shear strength in the heated state decreased significantly, which can reduce the blanking force. However, heating the material will produce oxide, will be deformation, therefore applied only to thick or the surface quality and precision of less demanding jobs. Lower 2. Ladder arrangement blanking punch In the multi-blanking punch in the punch made of different degrees south, a ladder Boubou set (Figure 2-18), will enable each punch the maximum blanking force of wood come together. Thereby reducing the total blanking force. Punch height difference between the thickness determined by: t 3mm h = 0.5t When the punch by step layout symmetrically as possible. At the same time should do a small punch shorter, longer doing big punch, so to avoid a small punch side material flow because the pressure caused by tilt or break situation. 3. Oblique incision Die Blanking Figure 2-u-shaped cloth ladder A model aimed Knife-edge blanking level, the entire flat edge on the contact sheet to the rather oblique knife edge blanking die, because edge is inclined, not simultaneously cut into the knife-edge blanking time, but gradually punching material, so very dry by punching a small section of the post. Thus lower. Second, the calculation of other blanking force Many factors affect these forces, mainly the mechanical properties and thickness, die gap, the workpiece shape and size and lubrication conditions. Therefore, the general experience with the following formula: Fx = KF (K look-up table 2-10) The overall strength based on the actual die stamping process concrete analysis of the structure. 冲 裁冲裁是利用模具使板科产生分离的冲压工序，包括落料与冲孔。它可以制成零件，也可为弯曲、拉延、成形等工序准备毛坯。从板科上冲下所需形状的零件(或毛坯)叫落科。在工件上冲出所需形状的孔(冲去的为废料)叫冲孔。如图I一1的垫圈，即由落科与冲孔两道工序完成。通过生产实践，我们对冲裁工序及其模具结构有了一定的了解，但感性认识上升到理性认识，才能真正了解冲裁过程的本质，更好地制定工艺和设计模具。下面就冲裁变形过程、冲裁件质量、冲裁模刀口尺寸设计及冲裁模结构设计等问题进行分析讨论。 第一节 冲裁变形机理冲裁过程由图12所示的冲裁变形过程可以看出，凸模与凹棋组成上下刃口，材料放在凹模上，凸模逐步下降使材料产生变形，直至全部分离完成冲裁。随着凸模作用在材料上的外力在数量上的变化，材料上的外力在数量上的变化，材料内部的变形不断发展。整个冲裁过程的变形分为三个阶段(图12)。1、弹性变形阶段凸模接触材队由于凸模加压，材料发生弹性压缩与弯曲并挤入凹模洞口。这时材料内应力没有超过屈服极限，若凸模卸压，材料即恢复原状，故称弹性变形阶段。2、塑性变形阶段凸模继续加压，材料内应力达到屈服极限，部份金属被挤入凹模洞口，产生塑剪变形，得到光亮的蛆切断面。因凸、凹摸间存在间陷，故在塑剪变形的同时还伴有材料的弯曲与拉伸。3、断裂分离阶段外力继续增加材料内应力不断增大，在凸、凹模刀口处由于应力集中，内应力首先越过抗剪强度，出现微裂。模继续下压，凸、凹模刃凹处的微裂不断向材料内部扩股，材料随即被拉断分离。如凸、凹模间隙合理时，上下裂纹互相重合。应力应变状态进一步分析冲裁时变形区的应力应变状态，有助予对冲裁过程的了解。在凹模和凸模刃口的联线上取单元体“，其应力应变图如图13所示。从图中可看出，似金属断裂线AB即刃口联线)成45度。的主铀方向I是拉应力与拉伸变形，拉应力使金属纤维伸长； 与其垂直的主轴方向2是压应力与压缩变形，使纤维受压挤；在切线方向的应力与应变很小，略去不计；与主应力方向成45。方向为最大剪应力方向而凸凹模之间存在间隙，使金属伸长并撕断，致使破断裂面粗糙，并带有毛刺。上述冲裁变形过程还可通过冲裁力的变化曲线图中得到确认。图2-9（教材），是冲裁厚为3毫米的材料时冲裁力与凸模行程的关系曲线。从图中可看出：在冲裁过程中冲裁力的大小是不断变化的。AB段相当于冲裁的弹性变形阶段，BC段为塑性变形阶段。当材料内应力达到抗剪强度时材料开始产生裂纹，CD段为裂纹扩展直至材料分离的断型阶队,DE段位推出材料件推出凹模口。剪切断面分析参见2-10图上述冲裁变形过程得到的冲栽件断面并不是光滑垂直的，断面存在三个区域，即圆角带、光亮带与断裂带。圆角带是在冲裁过程中塑性变形开始时由于金属纤维的弯曲与拉伸而形成的，软料比硬科的圆角大。光亮带是在变形过程的第二阶段金属产生塑剪变形时形成，有光滑垂直的表面，光亮带占全断面的1/21/3，软材料的光亮带宽，硬材料的光亮带窄。随材料机械性能，间隙，模具结构变化。断裂带相当于冲裁过程的第三阶段，主要是由于拉应力的作用，裂纹不断扩民金届纤维断扩展，故表面极糙不光滑，且有料度。在冲孔的断面上同样具有上述特征，只是三个区域的分布位置与落料相反。冲裁件除断面粗拖有维度外，还有点穹弯、不平整，端面有毛刺，所以冲裁只适用于一股要求的冲裁件。 第二节 模具间隙冲裁时不仅要求次冲出符合图纸形状叫零件，还应有一定质量要求，冲裁件质量是指切断面质量、尺寸精度及形状误差。切断面应平直，光洁、无裂纹和撕裂、夹层等缺陷、毛刺小零件，表面应尽可能平坦，即穹弓小，尺寸精度度保证不超出图纸规定的公差范围。影响冲裁件质量的因素很多，从生产实际知道，凸、凹模间隙大小及力的均匀性、模具刃口状态、模具结构与制造精度、材料品质等，对冲裁件都有影呐。但我们必须从其中找出对冲裁质量起着决定性作用的因素。间隙就是一个。1对冲裁断面质量的影响比较平直、光洁，且无毛刺。在这种情况下零件断面质量认为是良好的。当间隙过小时，则上下裂纹互不重合。当间隙过大时，裂纹也不重合。（参见2-11）若间隙分布不均，局部毛刺，磨损不均，加剧，所以间隙不仅要选用合理，而且在制造和调整冲模时保证间隙均匀。2.间隙对尺寸精度的影响冲裁件的尺寸精度指冲件的实际尺寸与公称尺寸的差值，差值越小则精度越高。这个差值包活两方面的偏差，一是冲裁件与凸模或凹模尺寸的偏差，一是模具本身的制造偏差。冲裁件与凸、凹模尺寸的偏差主要是由于：制件（废料）从凹模内推出，由于材料的弹性恢复造成的。偏差值可能是正， 也可能是负的。影响这个偏差值的因素有：1、凸、凹模间隙 间隙大，拉伸作用明显，弹性恢复使落料件小于凹模尺寸，冲孔件间隙小。 2、材料性质 材料性质对尺寸精度包有影响，因为材料性质其接决定了材料在冲裁形量。软纲的弹性变形量较小，冲裁后的弹性恢复量也就小，故工件精度较高。硬钢弹性恢复较大，工件精度就较低。 3、工件形状与尺寸。材料厚度与工件形状对只J哨度也有影响，薄材料冲裁盾的弹性恢复大，t件精度低。工件形状越复杂，模具创造及调整时就越难保证间隙匀，故尺寸偏差也越大。 4刃口状恋对断面质量的影晌5间隙对冲裁力的影响间隙愈小，冲裁变形区的静水压力愈高，材料的变亢力愈大冲裁力也就愈大，反之，当间隙增大时抗力降低，冲裁力也就减小，但减小的数值不大。（见图2-14）间隙对对模具寿命的影响（见教材略讲）第三节 凸凹模间隙的确定 由此可见，凸、凹模间隙对冲裁件质晨、冲裁力、模具寿命都有很大的影响，因此设计模具时定选择个合理的间隙，以保证冲裁件的断面质量好、所需冲裁小、模具寿命高。但是分别从质量、精度、冲裁力多方面的要求分别确定的合限间隙并不是同个数值，而是彼此接近，同时考虑到模县制造中的偏差及使用中的磨损，故生产中常是选择一个适当的范围为合理间隙，只要间隙落在这个范围内就可以冲出良好制件，这个范围的最小值称最小合理间隙Zmin小最大位称最大合理间隙Zmax。在最小合理隙Z Mi n时可以得到与板面垂直的断面，而不产生显著的毛刺。在最大间隙Zmax”仍能得到满意断面质量：只是个与板面不垂直。考虑到模具在使用过程中的磨损使间隙增大，故设计与制造新模时要采用最小合理间隙Zmin。确定合理间隙的方法有理论计算与经验确定法两种。一、理论确定法理论确定法的主要依据是要保证裂纹重合，以便获得良好的断面。团1冲裁过程中开始产生裂纹的瞬时状态q从图中的三角形AB c可求得间隙z式中：A，凸模压入深度； 最大剪应力方向与垂线间夹角； 从上式可看出，间隙z与材料厚度t、相对切入深度h。t以及裂纹方向日。有关，而以与又与材料性质有关，材料愈硬，h。t愈小。因此从上式可看出，影响间隙值的主要因素是材料性质和厚度。材料愈硬愈厚，所需合理间隙值愈大。表13为常用冲压材料的h。t与的近似值。由于各种材料的h。t与值目前还没有准确的测定数值，而且生产中使用这种法也不方便，故广泛采用经验公式与图表法。二、经验确定法经验确定法也是根据材料性质与厚度，按下式确定式中： K与材料性质有关的系数。 t材料厚度。软材料如08，l0，黄铜，紫铜Z=(00801)t中硬材科：A3，A 4，20，25Z(010I 2)t硬材如A5，50等Z(01-0.14)t其中薄料取下限。三、图
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