19.1 What are the reasons why the bulk deformation processes are important commercially and
technologically?
Answer. Reasons why the bulk deformation processes are important include the following: (1) they
are capable of significant shape change when hot working is used, (2) they have a positive effect on
part strength when cold working is used, and (3) most of the processes produce little material waste;
some are net shape processes.
19.2 Name the four basic bulk deformation processes.
Answer. The four basic bulk deformation processes are (a) rolling, (2) forging, (3) extrusion, and (4)
wire and bar drawing.
19.3 What is rolling in the context of the bulk deformation processes?
Answer. Rolling is a deformation process in which the thickness of the workpiece is reduced by
compressive forces exerted by two opposing rolls. The rolls rotate, thus pulling and simultaneously
squeezing the workpiece between them.
19.4 In rolling of steel, what are the differences between a bloom, a slab, and a billet?
Answer. A bloom is a rolled steel workpiece with a square cross section of about 150 mm by 150
mm. The starting work unit for a bloom is an ingot heated in a soaking pit. A slab is rolled from an
ingot or a bloom and has a rectangular cross section of about 250 mm by 40 mm. A billet is rolled
from a bloom and has a square cross section of about 40 mm by 40 mm.
19.5 List some of the products produced on a rolling mill.
Answer. Rolled products include flat sheet and plate stock, round bar and rod stock, rails, structural
shapes such as I-beams and channels.
19.6 What is draft in a rolling operation?
Answer. Draft is the difference between the starting thickness and the final thickness as the
workpiece passes between the two opposing rolls.
19.7 What is sticking in a hot rolling operation?
Answer. Sticking is a condition in hot rolling in which the surface of the workpiece adheres to the
rolls as the piece passes between the rolls, causing severe deformation of the metal below the surface
in order to allow passage through the roll gap.
19.8 Identify some of the ways in which force in flat rolling can be reduced.
Answer. Ways to reduce force in flat rolling include (1) use hot rolling, (2) reduce draft in each pass,
and (3) use smaller diameter rolls.
19.9 What is a two-high rolling mill?
Answer. A two-high rolling mill consists of two opposing rolls between which the work is
compressed.
19.10 What is a reversing mill in rolling?
Answer. A reversing mill is a two-high rolling mill in which the direction of rotation of the rolls can
be reversed to allow the work to pass through from either side.
19.11 Besides flat rolling and shape rolling, identify some additional bulk forming processes that use rolls
to effect the deformation.
Answer. Some other processes that use rolls are ring rolling, thread rolling, gear rolling, roll
piercing, and roll forging.
19.12 What is forging?
Answer. Forging is a deformation process in which the workpiece is compressed between two dies,
using impact or gradual pressure to form the part.
19.13 One way to classify forging operations is by the degree to which the work is constrained in the die.
By this classification, name the three basic types.
Answer. The three basic types are (1) open die forging, (2) impression die forging, and (3) flashless
forging.
19.14 Why is flash desirable in impression die forging?
Answer. Because its presence constrains the metal in the die to fill the details of the die cavity.
19.15 What is a trimming operation in the context of impression die forging?
Answer. Trimming is a shearing operation used to remove the flash on the workpiece after
impression die forging.
19.16 What are the two basic types of forging equipment?
Answer. The two types of forging machines are hammers, which impact the workpart, and presses,
which apply a gradual pressure to the work.
19.17 What is isothermal forging?
Answer. Isothermal forging is a hot forging operation in which the die surfaces are heated to reduce
heat transfer from the work into the tooling.
19.18 What is extrusion?
Answer. Extrusion is a compression forming operation in which a workpiece is forced to flow
through a die opening, thus taking the cross-sectional shape of the die opening.
19.19 Distinguish between direct and indirect extrusion.
Answer. In direct extrusion, also known as forward extrusion, a metal billet is loaded into a
container, and a ram compresses the material, forcing it to flow through a die opening at the opposite
end of the container. In indirect extrusion, also known as backward extrusion, the die is incorporated
into the ram, and as the ram compresses into the metal billet, the metal is forced to flow through the
die opening in a direction that is opposite (backwards) of the ram motion.
19.20 Name some products that are produced by extrusion.
Answer. Products produced by continuous extrusion include structural shapes (window frames,
shower stalls, channels), tubes and pipes, and rods of various cross sections. Products made by
discrete extrusion include toothpaste tubes, aluminum beverage cans, and battery cases.
19.21 Why is friction a factor in determining the ram force in direct extrusion but not a factor in indirect
extrusion?
19.1 What are the reasons why the bulk deformation processes are important commercially andtechnologically?Answer. Reasons why the bulk deformation processes are important include the following: (1) theyare capable of significant shape change when hot working is used, (2) they have a positive effect onpart strength when cold working is used, and (3) most of the processes produce little material waste;some are net shape processes.19.2 Name the four basic bulk deformation processes.Answer. The four basic bulk deformation processes are (a) rolling, (2) forging, (3) extrusion, and (4)wire and bar drawing.19.3 What is rolling in the context of the bulk deformation processes?Answer. Rolling is a deformation process in which the thickness of the workpiece is reduced bycompressive forces exerted by two opposing rolls. The rolls rotate, thus pulling and simultaneouslysqueezing the workpiece between them.19.4 In rolling of steel, what are the differences between a bloom, a slab, and a billet?Answer. A bloom is a rolled steel workpiece with a square cross section of about 150 mm by 150mm. The starting work unit for a bloom is an ingot heated in a soaking pit. A slab is rolled from aningot or a bloom and has a rectangular cross section of about 250 mm by 40 mm. A billet is rolledfrom a bloom and has a square cross section of about 40 mm by 40 mm.19.5 List some of the products produced on a rolling mill.คำตอบ ผลิตภัณฑ์รีดรวมแผ่นแบน และแผ่นหุ้น บาร์กลม และหุ้นเหล็ก ราง โครงสร้างรูปร่างคานและช่อง19.6 ร่างในกลิ้งคืออะไรคำตอบ ร่างเป็นความแตกต่างระหว่างความหนาเริ่มต้นและความหนาสุดท้ายเป็นการเทคโนโลยีผ่านระหว่างม้วนสองฝ่ายตรงข้าม19.7 อะไรจะติดในการดำเนินงานรีดร้อนคำตอบ ผสานเป็นเงื่อนไขในการรีดร้อนในที่พื้นผิวของการขึ้นรูปชิ้นงานสอดคล้องกับการม้วนเป็นชิ้นส่วนที่ผ่านไประหว่างม้วน แมพรุนแรงโลหะใต้ผิวหนังทำให้เกิดเพื่อให้เส้นทางผ่านช่องว่างของม้วน19.8 ระบุบางวิธีสามารถลดแรงในการรีดแบนคำตอบ (1) พร้อมใช้รวมถึงวิธีในการลดแรงในการรีดแบนรีด, (2) ลดร่างในแต่ละด่านและ (3) ใช้ขนาดเล็กเส้นผ่าศูนย์กลางม้วน19.9 โรงสีกลิ้งสองสูงคืออะไรคำตอบ โรงสีกลิ้งสองสูงประกอบด้วยสองม้วนฝ่ายตรงข้ามที่ทำงานอยู่การบีบอัดนั้น19.10 โรงสีกลับในกลิ้งคืออะไรคำตอบ โรงสีกลับเป็นโรงสีกลิ้งสูง 2 ทิศทางหมุนของม้วนสามารถสามารถย้อนกลับเพื่อให้งานผ่านจากด้านใดด้านหนึ่ง19.11 นอกแบนกลิ้งและกลิ้งรูป ระบุจำนวนมากบางเพิ่มเติมเป็นกระบวนการที่ใช้ม้วนลักษณะพิเศษที่แมพคำตอบ บางอื่น ๆ กระบวนการที่ใช้ม้วนเป็นแหวนกลิ้ง ด้ายกลิ้ง กลิ้งเกียร์ ม้วนpiercing, and roll forging.19.12 What is forging?Answer. Forging is a deformation process in which the workpiece is compressed between two dies,using impact or gradual pressure to form the part.19.13 One way to classify forging operations is by the degree to which the work is constrained in the die.By this classification, name the three basic types.Answer. The three basic types are (1) open die forging, (2) impression die forging, and (3) flashlessforging.19.14 Why is flash desirable in impression die forging?Answer. Because its presence constrains the metal in the die to fill the details of the die cavity.19.15 What is a trimming operation in the context of impression die forging?Answer. Trimming is a shearing operation used to remove the flash on the workpiece afterimpression die forging.19.16 What are the two basic types of forging equipment?Answer. The two types of forging machines are hammers, which impact the workpart, and presses,which apply a gradual pressure to the work.19.17 What is isothermal forging?Answer. Isothermal forging is a hot forging operation in which the die surfaces are heated to reduceheat transfer from the work into the tooling.19.18 What is extrusion?Answer. Extrusion is a compression forming operation in which a workpiece is forced to flowthrough a die opening, thus taking the cross-sectional shape of the die opening.19.19 Distinguish between direct and indirect extrusion.Answer. In direct extrusion, also known as forward extrusion, a metal billet is loaded into acontainer, and a ram compresses the material, forcing it to flow through a die opening at the oppositeend of the container. In indirect extrusion, also known as backward extrusion, the die is incorporatedinto the ram, and as the ram compresses into the metal billet, the metal is forced to flow through thedie opening in a direction that is opposite (backwards) of the ram motion.19.20 Name some products that are produced by extrusion.Answer. Products produced by continuous extrusion include structural shapes (window frames,shower stalls, channels), tubes and pipes, and rods of various cross sections. Products made bydiscrete extrusion include toothpaste tubes, aluminum beverage cans, and battery cases.19.21 Why is friction a factor in determining the ram force in direct extrusion but not a factor in indirectextrusion?
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