【正文】 ctangular blocks of precisionground steel that are inserted into milled pockets in the die shoes and sections called keyways. Keys located and heel die sections and ponents. 5. Pads A pad is simply a pressureloaded plate, either flat or contoured, that holds, control, or strips the metal during the cutting and forming processes. Several types of pads are used in stamping dies. Depending on their function, pads can be made from soft lowcarbon steel or hardened tool steel. Contoured pads must fit very closely to the mating die section. Precision requirements 天水師范學(xué)院工學(xué)院 2022屆 畢業(yè)設(shè)計(jì) 22 determine whether the pads are positioned with guide pins and bushing or left unguided. 6. Stripper pads/plates Stripper pads are flat or contoured springloaded plates that pull, or strip, the metal off the cutting punches. When it is cut, metal naturally tends to collapse around the body or shank of the cutting punches。 this is especially true during piercing. The stripper pad surrounds the cutting punches and mounts to the upper die shoe. As the punch exits the lower die, the springloaded pad holds the metal down flush with the lower die section, which allows the cutting punches to withdraw from the sheet metal or piece part. Often stripper pads are inserted with a small block of steel called a pad window. This pad window usually is small and lightweight and can be removed easily to allow the die maintenance technician to remove the ball lockstyle pierce punch form the retainer without removing the entire stripper pad. Stripper pads also function to hold the metal flat or to the desired shape during the cutting process. 7. Pressure Pads During the wipe bending process, the metal must be held down tightly to the lower die section before the forming punch contacts the metal. Pressure pads must apply a force that is at least equivalent to the bending force. Most pressure pads use highpressure coil or gas springs. When loaded with very highpressure spring, contoured or flat pads also can from sheet metal. These pad types often are referred to as power punches. 8. Draw Pads Draw Pads control metal flow during the drawing process. In drawing, the amount of pressure, or downward force, exerted on the sheet metal determines how much metal is allowed to flow and enter the draw die cavity. Too much pressure may stop the metal from flowing and cause splitting。 too little downward force may allow excess metal to flow inward and cause loose metal or wrinkling. Draw pads, often referred to as binders or blank holders, and usually are made from hardened tool steel. They can be flat or contoured, depending on the piece part shape. The process of Fine Blanking Fine blanking tooling is unique in its construction. When pared to conventional stamping tooling, there are a few specific features that set fine blanking tools apart. They are: 天水師范學(xué)院工學(xué)院 2022屆 畢業(yè)設(shè)計(jì) 23 Vring The Vring is a raised Vshaped ridge usually on the stinger plate that has the same contour as the blanking punch and is located close to it, roughly a distance equal to 50% of material thickness. In some cases the Vring is placed on the die plate, sometimes on both the die and stinger plate, and at times no Vring is used. Close punchdie clearance: This is another important feature of line blanking tooling, which enables the unique characteristics of line blanked parts to be created. Generally the clearance between punch and die is % of material thicknessper side. In some cases, depending on the material and application, zero clearance between punch and die is used. The minimal punchdie clearance is the key to obtaining the fully sheared edges that fine blanked parts are note for. This pare with a typical clearance of 10% of material thickness per side for conventional stamping tools. Straight die cavity The diecavity in fine blanking tool is straightnot tapered. This helps ensure the cleanly sheared edges and result in cut edges that are tapered approximately only a minimal taper enables tight dimensional control though the full thickness of the piece part. The straight die cavity also ensures that after the die plate is ground during regular die maintenance, the size of the die cavity does not grow. This ensures that the parts produced in every production run will maintain the same nominal dimensions as when the part was first made.. Tool Construction Fine blanking tools are pound dies, meaning that the part is ejected out of the die cavity. Most fine blanking dies are single station dies, with all feature created at one time with a single stroke of the press. Parts made in a single station tool have extremely consistent relationships between features. The use of progressive fine blanking dies is increasing rapidly, in an effort to provide more and more plex feature on parts right out of the tooleliminating secondary operation and enhancing design possibilities. There are two types of fine blanking tools: sliding punch and fixed punch. Generally, sliding punch tools are used for smaller and less plex parts, while fixed punch tools are used for larger and more plex parts. Sliding punch tools are less expensive to build, setup, and 天水師范學(xué)院工學(xué)院 2022屆 畢業(yè)設(shè)計(jì) 24 maintain, but are not as rigid as fixed punch toolsand cannot be used in every application. A typical fineblanking tool is a singlestation pound tool for producing a finished part in one press stroke. The only addition operation needed is the removal of a slight burr. The process requires a tripleaction fineblanking press. Closing force, counterpressure, and blanking pressure forces are individually and infinitely adjustable. How Fine Blanking Works: This represents a simple sliding punch fine blanking tool making a round washer with a hole at its center. 1. the tool closes, pressure embeds impingement ring into stock.