【正文】
ide guide ring is added to maintain straightness. The nest above the upper carbide guide ring serves as a guide for the punch during the operation. Figure 870 illustrates another forward extrusion die in which the punch creates the orifice through which the metal flows. The extruding pressure is applied through the punch guide sleeve. Combination Extruding Dies. A typical bination forward and backward extrusion die is shown in Figure 871. In this die, the two –piece pressure anvil acts as a bottom extruding punch and a shedder. The upper extruding punch is guided by a springloaded guide plate into which the guide sleeve is mounted. To maintain concentricity between the punch and die, the punch guide sleeve is centered into the die insert. Punch Design. The most important feature of punch design is end profile. A punch with a flat end face and a corner radius not over ″() can perate three times its diameter in steel, four to six times its diameter in aluminum. A punch with a bulletshaped nose or with a steep angle will cut through the phosphate coat lubricant quicker than a flatend punch. When the lubricant is displaced in extrusion, severe galling and wear of the punch will take palce. The punch must be free of grinding marks and requires a 4181。操作 成型的分類為 彎曲,拉伸,壓花,卷曲, 彎邊 ,扭曲,旋 壓 ,和孔翻邊。 表現(xiàn) 一些沖壓件性質(zhì)的幾種模具必須用于生產(chǎn)所需的形狀和形式。它將被歸類為通道成形模。該工具是最便宜和最簡(jiǎn)單的設(shè)計(jì)不一定是最好的 , 因?yàn)樗赡懿粫?huì)產(chǎn)生 符合 制圖規(guī)范 的沖壓件 。零件的尺寸可能會(huì)有所不同 ,變化可以 從 ″( 毫米)直徑或更小 的 ,到 需要足夠大的機(jī)械設(shè)備 來(lái) 搬運(yùn) 的 飛機(jī)或汽車 上的 零件。 為了最大限度的 減少?zèng)_頭失效 ,最 可取的 是壓印嵌條 密切配合 尺寸, 以保證同心度。一個(gè)典型的反擠壓模具 如 圖 867 所 示。這將是很好的支持硬塊。 正擠壓模具。圖 870 說(shuō)明了另一個(gè)正擠壓模,通過(guò)金屬流動(dòng)沖壓創(chuàng)建孔。在這兩個(gè)模具 中 , 兩 片壓砧 分別 作為底部擠壓凸模和頂出。凸模設(shè)計(jì)的最重要的特征是 端部輪廓 。沖頭必須無(wú)磨痕和需要一個(gè) 4181。 壓 力 砧的設(shè)計(jì)。 為了抵 抗 空心模 爆破壓力,工具鋼或硬質(zhì)合金模具環(huán)收縮到收縮環(huán)或模座 中。收縮環(huán)的推薦材料 是熱加工的合金工具鋼, 其硬化至 Rc 50 到 Rc52。彈簧導(dǎo)套 引導(dǎo) 沖頭 進(jìn)入 到 空心模, 并保持它們之間的同心度