纺纱学双语课英文习题库

纺纱学双语教学试题库及部分答案(英文)
第一部分：试题
Module1
Topic1 Yarn count
Review questions
1.Suppose you have two cotton yarns. The count of yarn A is 20 tex, and that of yarn B is 20 Nec. Which yarn is a thicker one? You need to justify your answer via proper count conversions.
2.If a worsted yarn has a count of 40 Nw (worsted count) at a regain level of 20%, what would be the count of this yarn, in tex, when it is oven-dried?
Topic 2 Yarn twist
Review questions
1."For a staple fibre yarn, the higher the twist, the stronger the yarn". Is this statement true? Why?
2.A yarn of 40 Nm (metric count) has a twist factor of 3,000
)
(tpm
tex⨯. What is the
twist level, in turns per metre, of this yarn?
3.If a yarn has an alpha metric (αm) of 100, what is the twist factor in the tex system (Kt) and the English cotton count system (Ke)? You need to show your working.
4.Assuming after twisting, the count of a multi-filament yarn is increased from 150 dtex to 180 dtex, what is the amount of twist contraction experienced by this multi-filament yarn?
Topic 3 The designation of yarn structures
Review questions
1.Describe yarns with the following designations:
(25 tex S420 + 60 tex Z80) S360; R89.2 tex
(25 tex S420 + 60 tex Z80) t0
(20 tex Z700 ⨯ 3 S400 + 34 tex S600) Z200; R96 tex
20 tex Z700 ⨯ 2 S400 ⨯3 Z200; R132 tex
Module2
Topic 1 Theoretical aspects of evenness
Review questions
1.In the calculation of limiting irregularity, information on fibre length is not used. This implies that fibre length has noting to do with the theoretical yarn evenness. Yet in practice, fibres with shorter length and higher length variations usually make less even yarns, other things being equal. How do you explain this 'discrepancy'?
2.A yarn is composed of 40/60 wool/cotton blend and has a linear density of 20 Nec (cotton count). The cotton has a fineness of
3.8 micronaire (inch g / ) and the wool has an average diameter of 19 μm (1 μm = 10-6 m) and a diameter CV of 25%. What is the limiting irregularity of this wool/cotton yarn? If the blend ratio is changed to 20/80 wool/cotton, is the yarn evenness likely to improve or deteriorate, compared with the 40/60 wool/cotton blend ratio? (you need to show your workings).
3.In his classical book "Studies of quality in cotton", published by Macmillan and Co., Limited in 1928, W. Lawrence Balls described such a paradox - the weaker the fibre, the stronger the yarn! Please explain this paradox, using the information provided in this topic.
Topic 2 Measurement and benchmarking of yarn evenness
Review questions
1.An ideal sliver of 70 mm mean fibre length is roller drafted with a draft of 10 under the following three conditions:
(a)Perfect roller drafting
(b)Presence of a large number of uncontrolled short fibres
©An eccentric back drafting roller with a diameter of 3 cm.
Explain how drafting under each condition will affect the evenness of the drafted sliver, and sketch and label the spectrogram for each drafting condition.
2.A 50 tex worsted yarn of 100% wool is measured for its evenness on the Uster evenness tester. If the CV of this yarn is 15%, how good is this yarn in relation to world production of similar yarns?
Module3
Topic 1 Short Staple Processing
Review questions
1. The key processing stages for cotton include
●opening and blending
●carding
●drawing
●combing
Describe the objectives and principle of each of these processes, using sketches if necessary and use about 200 words for each process.
2.Four bales of cotton, of 500 pounds each, are to be mixed together for the blow-room process. If the cotton fineness in these bales is,
3.8,
4.1, 4.4, and 3.3 micronaire (mic., μg/in.) respectively, what would be the theoretical fineness of the cotton in the mix? You need to show your calculations.
3.On a draw-frame or drawing machine, why is it often necessary to adjust the ratch setting according to the fibres to be processed?
4.With reference to the two-zone drawframe in figure 1.18 and assuming a break draft of 1.5 and a main draft of 4. If the average count of the eight input slivers is 12 ktex, what is the count of the single output sliver? If the delivery (front) roller speed is 400 m/min, what would be the approximate speed of the feed (back) rollers?
5.With reference to fibre hooks, explain why two passages of drawing are necessary between cotton carding and cotton combing. You should consider the following points:
●Hook generation in carding
●Hook removal during drafting
●Effect of hook direction on combing
Topic 2 Worsted Processing
Review questions
1.If a 20 tex weaving yarn is to be produced with an average number of 40 fibres in yarn cross section. What would be the right average diameter of the raw wool for the top-making process? You need to show the calculations involved and consider changes in fibre diameter during top-making.
2.In your own words and use sketches if necessary, explain how detergent helps to remove grease from the surface of wool during the aqueous wool scouring.
3.An important unit on a card is the cylinder/worker/stripper unit. Explain, with the help of
sketches, how this unit helps achieve the objectives of fibre opening, aligning, and mixing during carding.
4.With reference to carding, gilling and combing processes, explain why three intermediate gillings are commonly used in worsted top-making.
5.With reference to the geometrical model of fibre selection in worsted combing, explain:
(a)Why is possible to find a few fibres in the noil that are actually longer than some fibres in the combed sliver?
(b)What happens to the noil% and the mean fibre length of the combed sliver is the feed 'f' is increased?
Module4
Topic1 Ring spinning
Review questions
1. Based on the discussion in this topic, sketch the appearance of a typical ring spun yarn.
2. Rovings of 500 tex are used to feed a ring frame with 1000 spindles running at 20,000 rpm and 90% efficiency. A spinning draft of 20 is used to produce the ring spun yarn. If 54 kilograms of yarn are produced each hour on the machine, calculate the twist level in the yarn (t.p.m) and its twist factor (t.p.m.). Include details of your calculation.
3. One of the limitations of ring spinning is the relatively small amount of yarn on a full bobbin. Explain why we can not simply increase the ring radius and use a small empty bobbin to allow for a large quantity of yarn to be wound onto the bobbin before the full bobbin is doffed.
4. Explain, with the help of sketch, the principle of Sirospun and 2-for-1 twisting.
Topic2 Rotor spinning
Review questions
1.Based on the discussion of the characteristics of rotor spun yarns, draw a sketch depicting the key features of a typical rotor spun yarn.
2.This question relates to a yarn being spun on a rotor spinner under the following conditions:
input sliver 5.0 kTex
output yarn 50 tex
diameter of combing roll 70 mm
speed of combing roll 7,000 r.p.m.
rotor diameter 45 mm
rotor speed 100,000 r.p.
yarn delivery rate 200 m/min.
(a)Calculate the yarn twist level (t.p.m) and the twist factor of the rotor yarn, ignoring the small additional twist due to rotation of the yarn "peeling-off-point".
(b)If the above yarn is made from fibres all of the same length of 25 mm, what proportion of fibres will end up with some portion of their length in a wrapper configuration?
(c)In order to reduce the number of wrapper fibres, would it be more effective to use fibres which are 5 mm shorter, or use a rotor of 5 mm greater in diameter? Show your reasoning.
(d)Sliver for the above yarn received 2 drawframe passages between carding and spinning, with 6 doublings at each passage. Calculate the number of doublings provided during spinning and the total doublings the fibre assembly has received since carding.
(e)The fibre transport chute (between beater and rotor) has been designed so that fibres enter the chute at the speed of the beater surface, and are accelerated by air so that they leave the chute travelling 50% faster. Calculate the average number of fibres lying across the chute inlet at any one time and the corresponding value at chute outlet. (Take the linear density of the fibres to be
0.25 tex.)
(f)What are the finest yarns (expressed in Tex and English cotton count) that could be economically spun from fibres of linear density 0.25 tex on the rotor spinner. (Hint: consider the minimum nunber of fibres required for a rotor spun yarn).
3.In about 1,000 words, compare and contrast the technology of ring spinning and rotor spinning, with reference to the economics and yarn quality of each spinning system.
Topic3 Friction spinning
Review questions
1.Describe in your own words the principle of friction spinning.
2.Friction spun yarns do not have wrapper fibres on the yarn surface. Why are friction spun yarns weaker than comparable rotor spun yarns?
pare and contrast the differences and similarities between DREF 2 and DREF 3 friction spinning systems.
Topic4 Air jet spinning
Review questions
1.Rotor spun yarns have wrapper fibres and Murata jet spun yarns also have wrapping fibres binding the yarn together. What is the main difference between the structures of yarns produced by these two spinning systems?
2.The following diagrams show the process flow-chart for making two-folded (two-plied) ring and rotor spun yarns from cotton fibres. Please sketch the processing flow-charts for making two-folded cotton yarns from Murata Jet Spinner (MJS) and Murata Twin Spinner (MTS).
3、There are a number of spinning systems that are not discussed in this module. These spinning systems, while not as commonly used as the ones discussed in this module, are nevertheless worth knowing. Please consult the relevant library resources at Deakin and class handouts, explain (with the help of sketches) the working principle of each of the following spinning systems:
(1)Wrap spinning
(2)Self-twist spinning
(3)Mule spinning
(4)Woollen ring spinning
Topic5 Filament Yarn Texturing
Review questions
pare and contrast false twisting texturing with air-jet texturing. You should make reference to differences in filament input, the texturing process, and the resultant yarn. You can use sketches
to help explain the points.
2.Briefly describe the objective, principle, and process of filament intermingling.
第二部分 Answers:
1、What is the conversion factor between worsted count (Nw) and tex ?
ANS ：
2、If a yarn is 20 tex, what is the worsted count of this yarn?
Answer:
Using the conversion factor given above, the worsted yarn count is
3、Suppose a lot of worsted yarn is to be shipped to a buyer, and the gross weight of lot is 1000 kg. We now need to work out the commercial mass to invoice for the lot of yarn.
Answer :
We first extract a small sample (say 500 grams) from the lot. After oven drying of this small sample, the dried mass becomes, say, 450 grams. For worsted yarn, the conventional regain rate is 18.25% according to Table 1.2. Therefore, the commercial mass to invoice should be:
4. Explain:
133 dtex f40 S 1000; R 136 dtex (single-to-fold)
R 136 dtex f 40 S 1000; 133 dtex (fold-to-single)
ANS:
This describes a multifilament yarn of 136 dtex after twisting to 1000 t/m in the S direction. Before twisting, the count was 133 dtex, and the individual filament linear density is 133/40 =
3.3 dtex.
5. Explain:
20 tex Z 700 x 2 S 400 x 3 Z 200; R 132 tex (single-to-fold)
R 132 tex Z 200 / 3 S 400 / 2 Z 700; 20 tex (fold-to-single)
ANS:
This describes a cabled yarn built up from a singles yarn of 20 tex with 700 t/m Z, plied with itself with 400 t/m S, which is subsequently three-plied with 200 t/m Z twist.
Nw 3.44208.885=tex Nw 8.885=)(25.106410025.181005004501000kg =+⨯⨯
6. Explain: (25 tex S 420 + 60 tex Z 80) S 360; R 89.2 tex (single-to-fold)
R 89.2 tex S 360 / (S 420 + Z 80); 25 tex + 60 tex (fold-to-single)
ANS:
This describes a two ply yarn with dissimilar components, plied together in the S direction with 360 t/m
7. A wool/polyester blend yarn is manufactured on the worsted processing system. The yarn has a count of 30 tex and contains 45% wool and 55% polyester. The fibre fineness for the polyester staple is 2.5 dtex. The mean diameter of the wool fibres is 22 micron, with a CV of 25%. What is the limiting irregularity of this blend yarn?
ANS:
The blend yarn has a limiting irregularity of 12%.。