handbook of die design 2nd edition phần 4 pps

METALWORKING MACHINERY 215 FIGURE 5-2 Press drive principle: (1) Main shaft. (2) Pinion. (3) Gear. (4) Gear. (5) Driving belt. (6) Eccentric connection. (7) Connection link. (8) Slide adjustment. (9) Ram-retaining assembly. (10) Ram. (11) Counterweight. (Reprinted with permission from Müller Weingarten AG, Germany.) FIGURE 5-3 Joint mechanism: (1) Fixed point. (2) Connecting link. (3) Eccenter. (4) Rocker. (5) Gear assembly. (6) Main shaft. (7) Flywheel. (8) Ram connection. (Reprinted with permission from Müller Weingarten AG, Germany.) Suchy_CH05.qxd 11/08/05 10:51 AM Page 215 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. METALWORKING MACHINERY 5-1-3 Presses, According to Their Construction Variations due to the construction of presses allow for the distinction, based on types of press frames, as: • C-frame presses or gap-frame • Closed-frame presses or O-frame C-frame construction is often used with smaller-capacity presses. Their main advantage lies in the easily accessible work area, which accounts for shorter setup and adjustment times. This advantage is perhaps outweighed by their faults, mostly attributable to the shape of their frame, whose construction is likely to suffer from deflection under load. However, in current machine building, heavy tie rods and other reinforcements are used to secure the machine’s sturdiness and accuracy. These two groups of frame-dependent classification can be further divided into presses with a single column, double column, and pillar-supported presses (Fig. 5-7). 216 CHAPTER FIVE FIGURE 5-4 Double-column press. (Reprinted with permission from Müller Weingarten AG, Germany.) Suchy_CH05.qxd 11/08/05 10:51 AM Page 216 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. METALWORKING MACHINERY METALWORKING MACHINERY 217 FIGURE 5-5 Sectional view of the press mechanism without reduction gears: (1) Frame. (2) Control valve. (3) Clutch and brake. (4) Flywheel. (5) Clutch and brake. (6) Eccentric shaft. (7) Slide stroke adjustment. (8) Slide adjustment. (9) Overload safety device. (10) Slide. (11) Clamping block. (Reprinted with permission from Müller Weingarten AG, Germany.) Suchy_CH05.qxd 11/08/05 10:51 AM Page 217 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. METALWORKING MACHINERY 218 CHAPTER FIVE FIGURE 5-6 Sectional view of the press mechanism with reduction gears: (1) Frame. (2) Control valve. (3) Clutch and brake. (4) Flywheel. (5) Clutch and brake. (6) Reduction gearing. (7) Eccentric shaft. (8) Slide stroke adjustment. (9) Slide adjustment. (10) Overload safety device. (11) Slide. (12) Clamping block. (Reprinted with permission from Müller Weingarten AG, Germany.) Suchy_CH05.qxd 11/08/05 10:51 AM Page 218 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. METALWORKING MACHINERY METALWORKING MACHINERY 219 FIGURE 5-7 Press frame types. FIGURE 5-8 Presses with respect to the horizontal. Additionally, according to their width-to-height ratio and to the deviation from vertical, presses can be further categorized as vertical and horizontal presses, inclined or inclinable presses, and adjustable-bed presses (Fig. 5-8). Figures 5-9 through 5-14 show various presses. Figure 5-15 shows various drive systems. The so-called “straight-side” press frames consists of a press bed, which supports the bol- ster, the crown, two uprights, and the ram (i.e., slide). The uprights form a connection between the crown and the bed by either being bolted and keyed together, or by tie rods. Straight-side presses are usually more stiff than gap-frame presses. They additionally do not suffer from angular deflection, and where vertical deflection under a load is present, it is almost sym- metrical if their loading is symmetrical too. For these reasons, straight-side presses usually endanger the punch and die alignment the least. Another aspect, which affects unfavorably the gap-frame presses equipped with tie rods is the misalignment caused by the tie rods themselves. These connecting links, in order to provide the press with the stability and resistance to deflection it needs, have to be tightened so much that the whole press frame becomes subject to preload. This condition, naturally, Suchy_CH05.qxd 11/08/05 10:51 AM Page 219 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. METALWORKING MACHINERY 220 CHAPTER FIVE FIGURE 5-9 Straight-side, high-speed automatic press. Frame: high-tensile strength cast iron, four-piece tie rod construction. Crankshaft: full eccentric, forged alloy steel. Eight point gibbing. Flywheel or geared. 30–200 tons capacity, 60–500 strokes per minute. (Reprinted with permission from Minster Machine Co., Ohio.) Suchy_CH05.qxd 11/08/05 10:51 AM Page 220 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. METALWORKING MACHINERY METALWORKING MACHINERY 221 FIGURE 5-10 Straight-side press. Frame: four-piece tie rod construction. Crankshaft: full eccentric, made of forged alloy steel. Square gibs guide the slide front to back and left to right. Single geared twin drive. 200–1000 tons capacity, up to 150 strokes per minute. (Reprinted with permission from Minster Machine Co.,Ohio.) Suchy_CH05.qxd 11/08/05 10:51 AM Page 221 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. METALWORKING MACHINERY 222 CHAPTER FIVE FIGURE 5-11 C-frame hydraulic press. Frame: welded. Capacity: 250 to 2500 kN. Working speed up to 8–38 mm/sec. Maximum pressure 21 to 24.5 MPa. Electrohydraulic controls by Mannesmann Rexroth. (Reprinted with permission from OSTROJ, Opava, Czech Republic.) Suchy_CH05.qxd 11/08/05 10:52 AM Page 222 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. METALWORKING MACHINERY METALWORKING MACHINERY 223 FIGURE 5-12 Open-front power press. Notice the heavy tie rods. (Reprinted with permission from Müller Weingarten AG, Germany.) Suchy_CH05.qxd 11/08/05 10:52 AM Page 223 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. METALWORKING MACHINERY forces the ram and the bolster out of parallel which may endanger the tooling along with the press. The type of press drive used may introduce an additional variation. Figure 5-17 shows a single-point system of drives, in which the rod connecting the ram to the crankshaft is only one; a two-point system, in which the ram is tied to the crankshaft in two places; and a four-point system of drive variation, tied at four places. Most often the driving force is delivered from the upper area of the press, but sometimes even bottom-located driving sys- tems may be used. 5-2 PARTS OF THE PRESS Presses consist of several essential components, assembled within the mass of their frames. Years ago, the presses were simple and straightforward, but also limited in their function. Today’s presses contain electronic controls, including programming capacities, and altogether, they can work miracles. These previously rigid and unyielding machines can now be set and adjusted to provide for any whim and fancy of a demanding toolmaker, shop supervisor, or engineer. 224 CHAPTER FIVE FIGURE 5-13 Verson Model ETF-48-9-10TA Electronic Tri-Axis Transfer System with full pro- grammable servo control for up to 48 in. Transfer stroke, 9 in. Clamp stroke, and 10 in. Lift. Motion para- meters and die parameters, including the number of finger sensing and die sensing stations, can be programmed in the “die library menu” and displayed on the Smart Screen operator interface. (Reprinted with permission from Verson and Danly Division of Enprotech Mechanical Services, Inc., Lansing, MI.) Suchy_CH05.qxd 11/08/05 10:52 AM Page 224 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. METALWORKING MACHINERY [...]... at the Bottom of the Stroke Tons Crankshaft dia, in Singlecrank press 1.375 6 1.5 1.625 1.75 1.875 2.0 2.25 2.5 2.75 3.0 3.5 4. 0 4. 5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 9.0 10.0 11.0 12.0 13.0 14. 0 15.0 7 9 10 12 14 18 22 26 31 43 56 71 88 106 126 150 180 215 255 345 44 0 545 665 790 920 1060 Doublecrank press 22 26 31 43 56 71 88 106 126 150 180 215 255 345 45 0 650 900 1150 140 0 1700 of slightly off center force... the accommodation of the die It is measured off the top of the bed to the bottom of the slide, with the stroke down and adjustment up 5-3-3 Stroke Stroke of the press is the dimensional variation of the slide’s movement during the work cycle The stroke must always be greater than the dimensional distance a die has to travel to operate properly 5-3 -4 Rigidity of Press Construction One of the main reasons... disposed off while the product part travels on through the remainder of the die The terminology is different here, though both processes are basically the same and therefore belong to the same category, which is the process of metal cutting (Fig 6-1) The actual task of cutting is subject to many concerns The quality of surface of the cut, condition of the remaining part, straightness of the edge, amount of. .. 20 04 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website Suchy_CH05.qxd 11/08/05 10:52 AM Page 241 METALWORKING MACHINERY METALWORKING MACHINERY 241 the same category of products, with adjustments for their span of feeding movements, flexibility of their own positioning, and adaptability to different types of machines Automated devices must often... delivery of additional coils, or lift truck’s access for removal of finished parts Scrap cutters can chop the remaining strip into small pieces, which will easily fit a scrap bin and be disposed of Where a scrap cutter cannot be added as a component of the die because of additional press force needed for its operation, stand-alone scrap cutters should be utilized Often, just better planning of the die layout... visible 5-6-3 Die Positioning Presses are bulky, heavy, and sturdy machines, but they are extremely alignment-sensitive Incorrect mounting of the die may only cause additional damage For example, mounting of a die off center (left-to-right) will place a heavy pressure on the gibs and the ram, and on all connecting elements Mounting the die off center (back to front) may leave a portion of the ram unsupported... for production of pockets in the metal material, or for grinding, polishing, and similar finishing operations The process uses a rotating electrode, and the coolant is of an erosive nature, the action of which speeds up the removal of material while slowing down the wear of electrode However, the accuracy of this method is less than that of EDM Because of the widespread utilization of EDM machining,... website Suchy_CH05.qxd 11/08/05 10:52 AM Page 248 METALWORKING MACHINERY Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 20 04 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website Suchy_CH06.qxd 11/08/05 10: 54 AM Page 249 Source: HANDBOOK OF DIE DESIGN CHAPTER 6 BLANKING AND PIERCING OPERATIONS... used for separating a piece of material of predetermined shape and size from the remaining portion of a strip or sheet of metal It is one of the most extensively used processes throughout die and sheet-metal work It consists of several different material-parting operations, such a piercing, perforating, shearing, notching, cutoff, and blanking In blanking, the piece is cut off from the sheet, and it... off-center force should be located in 1 /4 of the width of the press (left-to-right), and in 1 /4 of the depth (front-to-back) The force should be equal to 1 /4 of the max press force Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 20 04 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website Suchy_CH05.qxd . 31 3.5 43 43 4. 0 56 56 4. 5 71 71 5.0 88 88 5.5 106 106 6.0 126 126 6.5 150 150 7.0 180 180 7.5 215 215 8.0 255 255 9.0 345 345 10.0 44 0 45 0 11.0 545 650 12.0 665 900 13.0 790 1150 14. 0 920 140 0 15.0. accommodation of the die. It is mea- sured off the top of the bed to the bottom of the slide, with the stroke down and adjust- ment up. 5-3-3 Stroke Stroke of the press is the dimensional variation of the. off-center force should be located in 1 / 4 of the width of the press (left-to-right), and in 1 / 4 of the depth (front-to-back). The force should be equal to 1 / 4 of the max. press force. Suchy_CH05.qxd