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engineering
mechanical engineering
Manufacturing Processes for Engineering Materials 5th edition Serope Kalpakjian, Steven Schmid - Solutions
Due to preferred orientation (see Section 3.5), materials such as iron can have higher magnetism after cold rolling. Recognizing this feature, plot your estimate of LDR vs. degree of magnetism.
Explain why a metal with a fine-grain micro-structure is better suited for fine blanking than a coarse-grained metal.
What are the similarities and differences between roll forming, described in Section 7.4.4, and shape rolling, described in Section 6.3.5?
Inspect a common paper punch and comment on the shape of the tip of the punch as compared with those shown in Fig. 7.12.
Explain how stringers can adversely affect bend-ability. Do they have a similar effect on formability?
In Fig. 7.56, the caption states that zinc has a high c/a ratio, whereas titanium has a low ratio. Why does this have relevance to limiting drawing ratio?
Review Eqs. (7.12) through (7.14) and explain which of these expressions can be applied to incremental forming.
Referring to Eq. (7.5), it is stated that actual values of e0 are significantly higher than the values of e" due to the shifting of the neutral axis during bending. With an appropriate sketch, explain this phenomenon.
Note in Eq. (7.11) that the bending force is a function of t2. Why?
Calculate the minimum tensile true fracture strain that a sheet metal should have in order to be bent to the following R/t ratios: (a) 0.5, (b) 2, (c) 4. (See Table 7.2.)
Estimate the maximum bending force required for a 1/8-in. thick and 12-in. wide Ti-5Al-2.5Sn titanium alloy in a V-die with a width of 6 in.
In Example 7.4, calculate the work done by the force-distance method, noting that work is the integral product of the vertical force, F, and the distance it moves.
What would be the answer to Example 7.4 if the tip of the mechanism applying the force, F, were fixed to the strip by some means, thus maintaining the lateral position of the force?
Calculate the magnitude of the force F in Example 7.4 when α = 30°.
Explain how you would estimate the temperature rise in the shear zone in a shearing operation.
How would the force in Example 7.4 vary if the workpiece were made of a perfectly plastic material? Explain.
Calculate the press force required in punching 0.5-mm-thick 5052-O aluminum foil in the shape of a square hole 30 mm on each side.
A straight bead is being formed on a 1-mm-thick aluminum sheet in a 20-mm-diameter die cavity, as shown in the accompanying figure. (See also Fig. 7.25a.) Considering springback, calculate the outside diameter of the bead after it is formed and unloaded from the die. Let Y= 150 MPa.
Inspect Eq. (7.10) and substituting in some numerical values, show whether the first term in the equation can be neglected without significant error in calculating springback.
In Example 7.5, calculate the amount of TNT required to develop a pressure of 10,000 psi on the surface of the workpiece. Use a standoff of 1 foot.
Estimate the limiting drawing ratio for the materials listed in Table 7.3.
For the same material and thickness as in Problem 7.66, estimate the force required for deep drawing with a blank diameter of 10 in. and a punch diameter of 9 in.
A cylindrical cup is being drawn from a sheet metal that has a normal anisotropy of 3. Estimate the maximum ratio of cup height to cup diameter that can successfully be drawn in a single draw. Assume that the thickness of the sheet throughout the cup remains the same as the original blank thickness.
Obtain an expression for the curve shown in Fig. 7.56 in terms of the LDR and the average normal anisotropy, R.
A steel sheet has R values of 1.0, 1.5, and 2.0 for the 0°, 45°, and 90° directions to rolling, respectively. For a round blank 150 mm in diameter, estimate the smallest cup diameter to which it can be drawn in one draw.
As a practicing engineer in manufacturing, why would you be interested in the shape of the curve shown in Fig. 7.7? Explain.
In Problem 7.79, explain whether ears will form and, if so, why. In problem A steel sheet has R values of 1.0, 1.5, and 2.0 for the 0°, 45°, and 90° directions to rolling, respectively. For a round blank 150 mm in diameter, estimate the smallest cup diameter to which it can be drawn in one draw.
A 1-mm-thick isotropic sheet metal is inscribed with a circle 4 mm in diameter. The sheet is then stretched uniaxially by 25%. Calculate(a) The final dimensions of the circle and(b) The thickness of the sheet at that location.
Conduct a literature search and obtain the equation for a tractrix curve, as used in Fig. 7.61.
Estimate the maximum power in shear spinning a 0.5-in.-thick annealed 304 stainless steel plate that has a diameter of 12 in. on a conical mandrel of a = 30°. The mandrel rotates at 100 rpm and the feed is f = 0.1 in./rev.
Obtain a common aluminum beverage can and cut it in half lengthwise with a pair of tin snips. Using a micrometer, measure the thickness of the bottom of the can and of the wall. Estimate(a) The thickness reductions in ironing of the wall and(b) The original blank diameter.
What is the force required to punch a square hole, 150-mm on each side, from a 1-mm-thick 5052-0 aluminum sheet using flat dies? What would be your answer if beveled dies were used instead?
Estimate the percent scrap in producing round blanks if the clearance between blanks is to be one-tenth of the radius of the blank. Consider single- and multiple-row blanking, as shown in the accompanying figure.
Plot the final bend radius as a function of initial bend radius in bending for (a) 5052-O aluminum, (b) 5052-H34 aluminum, (c) C24000 brass, (d) AISI 304 stainless steel sheet.
Do you think the presence of burrs can be beneficial in certain applications? Give specific examples.
The accompanying figure shows a parabolic profile that will define the mandrel shape in a conventional spinning operation. Determine the equation of the parabolic surface. If a spun part is to be produced from a 10-mm-thick blank, determine the minimum blank diameter required. Assume that the
For the mandrel needed in Problem 7.90, plot the sheet-metal thickness as a function of radius if the part is to be produced by shear spinning. Comment on whether or not this operation is feasible.
Consider several shapes (such as oval, triangle, L-shaped, etc.) to be blanked from a large flat sheet by laser-beam cutting. Sketch a nesting layout to minimize ip.
Give several structural applications in which diffusion bonding and superplastic forming can be used jointly.
On the basis of experiments, it has been suggested that concrete, either plain or reinforced, can be a suitable material for dies in sheet-metal forming operations. Describe your thoughts regarding this suggestion, considering die geometry and any other factors it may be relevant.
Metal cans are either of the two-piece variety (in which the bottom and sides are integral) or the three-piece variety (in which the sides, the bottom, and the 3pare each separate pieces). For a three-piece can and assuming that it can be considered as a thin-walled, internally-pressurized vessel,
Investigate methods for determining optimum shapes of blanks for deep-drawing operations. Sketch the optimally shaped blanks for drawing rectangular cups, and optimize their layout on a large sheet of metal.
The design shown in the accompanying illustration is proposed for a metal tray, the main body ofwhich is made from flat cold-rolled sheet steel. Noting its features and that the sheet is bent in two different directions, comment on relevant manufacturing considerations. Include factors such as
Design a box that will contain a 4 in. × 6 in. × 3 in. volume. The box is to be produced from two pieces of sheet metal and will require no tools or fasteners for its assembly.
Explain why the cutting force, Fc, increases with increasing depth of cut and decreasing rake angle.
It has been stated that it is generally undesirable to allow temperatures to rise excessively in machining operations. Explain why.
Give examples of (a) Forced vibration (b) Self-excited vibration in general engineering practice.
Tool temperatures are low at low cutting speeds and high at high cutting speeds, but low again at even higher cutting speeds. Explain why.
Explain the technical innovations that have made high-speed machining advances possible, and the economic motivations for high-speed machining.
Explain the reasons that the same tool life may be obtained at two different cutting speeds.
Inspect Table 8.6 and identify tool materials that would not be particularly suitable for interrupted cutting operations, such as milling. Explain your choices.
Explain the possible disadvantages of a machining operation in a discontinuous chip is produced.
It has been noted that tool life can be almost infinite at low cutting speeds. Would you then recommend that all machining be done at low speeds? Explain.
Explain why studying the types of chips produced is important in understanding machining operations.
How would you expect the cutting force to vary for the case of serrated-chip formation? Explain.
Wood is a highly anisotropic material; that is, it is orthotropic. Explain the effects of orthogonal cutting of wood at different angles to the grain direction on the types of chips produced.
Describe the advantages of oblique cutting. Which machining processes involve oblique cutting? Explain.
What are the effects of performing a cutting operation with a dull tool tip? A very sharp tip?
Explain why it is possible to remove more material between tool resharpenings by lowering the cutting speed.
Explain the significance of Eq. (8.8).
How would you go about measuring the hot hardness of cutting tools? Explain any difficulties that might be involved.
Describe the reasons for making cutting tools with multiphase coatings of different materials. Describe the properties that the substrate for multiphase cutting tools should have for effective machining.
Explain the advantages and any limitations of inserts. Why were they developed?
Make a list of alloying elements in high-speed-steel cutting tools. Explain why they are used.
What are the purposes of chamfers on cutting tools? Explain.
Why does temperature have such an important effect on cutting-tool performance?
Ceramic and cermets cutting tools have certain advantages over carbide tools. Why, then, are carbide tools not replaced to a greater extent?
Why are chemical stability and inertness important in cutting tools?
Describe the trends that 'you observe in Tables 8.1 and 8.2.
What precautions would you take in machining with brittle tool materials, especially ceramics? Explain.
Why do cutting fluids have different effects at different cutting speeds? Is the control of cutting-fluid temperature important? Explain.
Which of the two materials, diamond or cubic boron nitride, is more suitable for machining steels? Why?
List and explain the considerations involved in determining whether a cutting tool should be reconditioned, recycled, or discarded after use.
List the parameters that influence the temperature in machining, and explain why and how they do so.
List and explain the factors that contribute to poor surface finish in machining operations.
Explain the functions of the different angles on a single-point lathe cutting tool. How does the chip thickness vary as the side cutting-edge angle is increased? Explain.
It will be noted that the helix angle for drills is different for different groups of workpiece materials. Why?
A turning operation is being carried out on a long, round bar at a constant depth of cut. Explain what differences, if any, there may be in the machined diameter from one end of the bar to the other. Give reasons for any changes that may occur.
Describe the relative characteristics of climb milling and up milling and their importance in machining operations.
To what factors would you attribute the large difference in the specific energies within each group of materials shown in Table 8.3?
In Fig. 8.64a, high-speed-steel cutting teeth are welded to a steel blade. Would you recommend that the whole blade be made of high-speed steel? Explain your reasons.
Describe the adverse effects of vibrations and chatter in machining.
Make a list of components of machine tools that could be made of ceramics, and explain why ceramics would be a suitable material for these components.
In Fig. 8.12, why do the thrust forces start at a finite value when the feed is zero? Explain.
Describe the effects of tool wear on the workpiece and on the overall machining operation.
Explain whether or not it is desirable to have a high or low (a) N value (b) C value in the Taylor tool-life equation.
Are there any machining operations that cannot be performed on (a) Machining centers (b) Turning centers? Explain.
What is the significance of the cutting ratio in machining?
Emulsion cutting fluids typically consist of 95% water and 5% soluble oil and chemical additives. Why is the ratio so unbalanced? Is the oil needed at all? Explain.
Describe the effects of cutting fluids on chip formation. Explain why and how they influence the cutting operation.
It was stated that it is possible for the n value in the Taylor tool-life equation to be negative. Explain.
Assume that you are asked to estimate the cutting force in slab milling with a straight-tooth cutter. Describe the procedure that you would follow.
Explain the possible reasons that a knife cuts better when it is moved back and forth. Consider factors such as the material being cut, interfacial friction, and the shape and dimensions of the knife.
What are the effects of lowering the friction at the tool-chip interface (say with an effective cutting fluid) on the mechanics of cutting operations? Explain giving several examples.
Why is it not always advisable to increase cutting speed in order to increase production rate? Explain.
It has been observed that the shear-strain rate in metal cutting is high even though the cutting speed may relatively low. Why?
We note from the exponents in Eq. (8.30) that the cutting speed has a greater influence on temperature than does the feed. Why?
What are the consequences of exceeding the allowable wear land (see Table 8.5) for cutting tools? Explain.
Comment on and explain your observation regarding Figs. 8.34, 8.38, and 8.43.
It was noted that the tool-life curve for ceramic cutting tools in Fig. 8.22a is to the right of those for other tools. Why?
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