TT 252 > Test 3 > Flashcards

Test 3 Flashcards

(61 cards)

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1
Q

Weaving

A

The process of converting two sets of orthogonal yarns to woven fabrics

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2
Q

What will the weaving machine produce

A

a given fabric with required fabric construction parameters

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3
Q

What does woven fabric construction parameters influence

A

Warp Density
Pick Density
Warp Yarn Number and fiber content
Filling Yarn Number and fiber content
Warp yarn Crimp
Filling Yarn Crimp
Weave design

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4
Q

Warp Density

A

The number of warp yarns/unit fabric width

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5
Q

Pick Density

A

The number of picks/unit fabric length

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6
Q

Primary Motions

A

series of cyclic essential motions to form a fabric for the weaving machine

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7
Q

The Primary Motions Include

A
  1. Shedding motion which is executed by shedding mechanism
  2. filling insertion potion
  3. Beat-up motion
  4. Warp and fabric control (take up and let off motions)
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8
Q

Th shedding Motion

A

the motion forms the shed by dividing the warp ends into two sheets, providing a path for the filling insertion element

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9
Q

How is the division of warp yarns conducted in the shedding motions

A

raising or lowing the harnesses

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10
Q

Harnesses movement is dictated by..

A

the weave design and the pattern of assigning warp ends to harnesses

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11
Q

What are the two steps of the shedding motions

A
  1. Warp ends are leveled
  2. Shedding is formed
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12
Q

Filling Insertion Motion

A

Follows the shedding motion, the motion forces of releases the filling insertion element, which carries the filling yarn through the open shed

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13
Q

Beat-up motion

A

The newly inserted filling yarn or pick is pushed at high force to the fell of the cloth by the reed wires

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14
Q

Warp and Fabric Control

A

woven fabric is collected on a cloth roll.

The cloth roll is rotated by the take-up motion to collect a fabric length that equals the space between two picks

Simultaneously, the warp is released or fed through the loom to substitute for the amount of fabric that is taken up by the cloth roll (let-off motion)

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15
Q

Let Off Motion in Weaving

A

The warp is released or fed through the loom to substitute for the amount of fabric that is taken up by the cloth roll

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16
Q

the relationship between take-up and let off motions

A

dependent

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17
Q

What are the three type sof shedding motions

A
  1. Cam
  2. Dobby
  3. Jacquard
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18
Q

What are the components of the shedding cam

A
  1. Cam following
  2. cam profile
  3. Cam shaft
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19
Q

How many harnesses doe sthe cam control

A

one

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20
Q

How is the cam profile constructed

A

according to the weave design

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21
Q

How is the cam follower motion transferred to the harness

A

through links

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22
Q

The Dobby

A

made to overcome the limitations of cams, more compact compared to cam

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23
Q

What is the maximum number of harness that can be operated by a dobby

A

40

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24
Q

Jacquard

A

Capable of producing large and intricate weave designs that are beyond the scope of dobby. It is possible to control every warp end individually

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25
The three filling insertion systems
Sold, Fluid, Inertia
26
What systems fall under Solid
Shuttle, Papier, Projectile
27
What systems fall under Fluid
Air Jet, Water Jet
28
What systems fall under inertia
Friction Drive
29
Function of let-off
1. Controls the warp sheet tension at a a predetermined level 2. feeds the warp sheet through the weaving machine
30
What are the types of let off
negative, semi positive, positive
31
Take-up functions
1. Collects the woven fabric on a cloth roll 2. controls the pick (weft) density
32
Type sof take-off
Direct, Indirect
33
Advantages of off Loom Cloth roll
- Produces large cloth rolls - less doffing less labor - less number of empty tubes - less seam in penetration for dyeing an dfinishing - less cut out fabric at the seam - inspection station can be installed - quality problems can be identified and corrdtced
34
Loom Timing
The loom timing is usually based on the position of the main shaft in a weaving cycle (one pick).
35
The position of the main shaft angle is measured in
degrees. After completing one weaving cycle (produce one pick), the main shaft rotates one revolution (360º)
36
What happens after completing one weaving cycle
The main shaft rotates one revolution (360º)
37
Loom timing diagram
The diagram depicts the start and end of each primary event of different weaving motions.
38
What are the start and the end of events of the loom timing based on
loom type, fabric type, and fabric width
39
The objectives of weaving secondary motions
q. increase weaving productivity 2. enhance woven fabric quality 3. produce fancy effects 4. reduce labor cost
40
Warp stop motion
device on a loom that automatically stops the machine when a warp yarn breaks.
41
How does warp stop motion piece the yarn
threading it back through the drop wire, heddle, and reed, and then restarts the loom.
42
Filling stop motion
stops the weaving process when a filling yarn is absent. The detection of the filling yarn is achieved by optic sensors that are usually placed at the end of insertion. The repair is done manually by the weaver.
43
Filling Detection and Repair
stops the weaving process when a filling yarn is absent. The detection of the filling yarn is achieved by optic sensors that are usually placed at the end of insertion. The repair is done automatically without intervention from the weaver. Then the machine starts automatically
44
Warp Protector Motion
stops the weaving process if the shuttle (or gripper) did not arrive (checked-in) inside the shuttle box.
45
What is the warp projector motion used in
solid filling insertion
46
How is the detection achieved in the warp projector motion
The detection of the presence or absence of the shuttle is achieved by optic or magnetic sensor.
47
Filling Insertion Role
Used when a fabric needs more than one type of filling (weft) yarn. It allows different yarns to be used for decorative designs or special fabric purposes.
48
Automatic pattern or weave change
electronic dobby / jacquard weaving machine
49
two ways the automatic weave or pattern change is avalible
Manual Load: The pattern is created in CAD, saved to a floppy disk, and loaded into the loom’s computer. The loom must stop briefly during loading. Automatic Switch: The loom stores several patterns and can change between them automatically without stopping.
50
Why are shuttle looms slow with a low production rate
The shuttle carries the filling package, and so the shuttle has large dimensions and a heavy mass
51
The large dimensons of shuttle weaving dictate
1. larger time to open and close the shed to provide a clear path for the shuttle to fly through the shed 2. longer transit time of the shuttle through the shed
52
How is the shed time influenced by shuttle height
higher shuttle height requires longer time to form shed
53
How is shed size influenced by shuttle width
wider shuttle requires longer time to form the shed
54
What are the limitations with acceleration in shuttle weaving
The acceleration rate is limited due to the shuttle heavy mass. Too high acceleration (and hence deceleration) may cause high impact forces between the shuttle, picker and shuttle boxes parts.
55
How can high force effect shuttle weaving
too high forces lead to damaging of loom parts
56
disadvantages of shuttle weaving
- low production rates - high levels of noise - high levels of vibrations - requires quill winding
57
What are features of a Rapier
- Not used for wide fabrics - Works with any yarn type - Handles light to heavy filling yarns - Faster than a shuttle loom
58
features of the Gripper (projectile)
- capable of producing wide fabrics - can handle any yarn type - cannot handle large flat continuous filling yarns - does not need large space to hold the gripper - the same speed as the rapier
59
features of Air Jet
- not used for wise fabric production - cannot handle fancy yarns of different thickness - cannot handle heavy yarns - cannot handle highly twisted yarns - needs compressed air - higher speed than gripper and rapier
60
water jet feautres
- cannot handle highly twisted yarns - used for continuous filament yarns that do not absorb water - special size formula for the warp - highest speed but less development
61
monitoring Weaving Efficiency
- computerized data collection systems - classifies short term stops (warp, filling, other stops) - allows subclassification of stop type - Subclassification may be done for low efficiency styles by hand held data collection system, then upload to main system
TT 252
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