Jacquard Loom Calculation for Fabric Weaving
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Questions and Answers

What is the primary function of the hook in the jacquard shedding mechanism?

  • To hold the pattern card
  • To push the needles
  • To lift the harness (correct)
  • To lower the harness

    • What is the purpose of the spring on the left side of each needle?

  • To attach the dead weights to the harness
  • To hold the hook in place
  • To lift the harness
  • To push the needles against the pattern card (correct)

    • In a single cylinder jacquard, how many operating cylinders are available?

  • Four
  • Two
  • One (correct)
  • Three

    • What is the purpose of the dead weights attached to the harness in the jacquard shedding mechanism?

    <p>To lower the harness</p> Signup and view all the answers

    How many needles are there in a single lift jacquard for each end in the repeat?

    <p>One</p> Signup and view all the answers

    What is the direction of the curved or kinked needle around the vertical hook?

    <p>Vertical</p> Signup and view all the answers

    What is the function of the double roller or pulley system?

    <p>To move the harness up and down</p> Signup and view all the answers

    What is the purpose of the retaining hooks (d) and (e)?

    <p>To catch the hooks depending on the weave design</p> Signup and view all the answers

    What happens when the right-hand solenoid (H) is energized?

    <p>The retaining hook (d) does not catch the hook (b)</p> Signup and view all the answers

    What is the position of the harness at point (1)?

    <p>Bottom position</p> Signup and view all the answers

    What happens to the hook (c) and its knife (g) at point (3)?

    <p>They reach the top position</p> Signup and view all the answers

    What happens to the harness at point (3)?

    <p>It remains in the bottom position</p> Signup and view all the answers

    What is the formula to calculate the number of repeats handled by a jacquard?

    <p>Jacquard capacity/(Ends per repeat)</p> Signup and view all the answers

    What is the utilization of jacquard capacity in terms of ends per repeat?

    <p>Number of repeats handled by jacquard x Ends per repeat</p> Signup and view all the answers

    What is the purpose of casting out in jacquard shedding mechanisms?

    <p>To achieve a warp thread density less than harness density</p> Signup and view all the answers

    What is the maximum ends per inch achievable on a loom with a jacquard shedding mechanism?

    <p>Harness density</p> Signup and view all the answers

    What is the formula to calculate the width of a repeat?

    <p>Ends per repeat/Ends per inch</p> Signup and view all the answers

    What is the effective jacquard capacity after casting out?

    <p>Jacquard capacity - Number of ends cast out</p> Signup and view all the answers

    What is the total number of ends in a fabric with a width of 60 inches and 60 ends per inch?

    <p>3600</p> Signup and view all the answers

    How is the number of repeats handled by a jacquard calculated?

    <p>Jacquard capacity / Ends per repeat</p> Signup and view all the answers

    What is the utilized jacquard capacity in a fabric with 3 repeats handled by the jacquard and 200 ends per repeat?

    <p>600</p> Signup and view all the answers

    How are harnesses per hook calculated in a jacquard loom?

    <p>Total ends / Utilized jacquard capacity</p> Signup and view all the answers

    In the example given, what is the number of harnesses per hook?

    <p>6</p> Signup and view all the answers

    What is the rate of the cylinder's rotation in a DLSC jacquard loom that produces 300 picks per minute?

    <p>300 times per minute</p> Signup and view all the answers

    What is the advantage of DLSC jacquard over SLSC jacquard?

    <p>It produces a semi-open shed</p> Signup and view all the answers

    What happens when an end has to remain in the bottom position for two consecutive picks in a DLSC jacquard?

    <p>It remains at the bottom without any intermediate movement</p> Signup and view all the answers

    In a DLDC jacquard, how many hooks are controlled by each harness or end?

    <p>Two hooks</p> Signup and view all the answers

    What is the purpose of the two cylinders in a DLDC jacquard?

    <p>One cylinder carries the pattern card for odd numbered picks and the other for even numbered picks</p> Signup and view all the answers

    How many hooks are there in a 400 capacity DLDC machine?

    <p>800 hooks</p> Signup and view all the answers

    Study Notes

    Jacquard Shedding Mechanism

    • Single Lift Single Cylinder (SLSC) Jacquards have one operating cylinder, whereas Double Cylinder Jacquards have two cylinders, one for odd picks and one for even picks.

    SLSC Jacquard Mechanism

    • The mechanism completes its cycle once in every pick, being single lift and negative in action.
    • Lifting of harness is achieved through jacquard hooks, while lowering is done by dead weights attached to the harness.
    • Each hook is connected to a harness after passing through a grate.
    • A double roller or pulley system is used to move the harness up and down.

    Operating Cycle

    • The initial position has hook (b) and its knife (f) in the uppermost position, while hook (c) and its knife (g) are in the lowermost position.
    • The harness is at the bottom position at the initial stage.
    • To remain lowered in the next pick, the right-hand solenoid is energized, and the retaining hook (d) does not catch hook (b).
    • The knife (g) will then go up, taking hook (c) up, and the knife (f) will go down, taking hook (b) down.

    Jacquard Capacity and Utilization

    • Jacquard capacity = 10 x 40 = 400
    • Total ends = 60 x 50 = 3000
    • Number of repeats handled by jacquard = Jacquard capacity / (Ends per repeat) = 400 / 150 = 2.66 or 2
    • Utilized jacquard capacity = Number of repeats handled by jacquard x Ends per repeat = 2 x 150 = 300
    • Harnesses per hook = Total ends / Utilized jacquard capacity = 3000 / 300 = 10
    • Width of repeat = (Ends per repeat) / (Ends per inch) = 150 / 60 = 2.5"
    • Height of repeat = (Picks per repeat) / (Picks per inch) = 300 / 60 = 5"

    Casting Out

    • Warp thread density can be controlled by changing the reed count and reed plan in shedding mechanisms other than jacquard.
    • However, every jacquard has a specific harness density, and the maximum ends per inch achievable on the loom is equal to the harness density.
    • Casting out is used to achieve warp thread density less than harness density.

    DLSC and DLDC Jacquards

    • In Double Lift, Single Cylinder (DLSC) jacquard, the cylinder turns once, but the knives reciprocate (rise and fall) half the time.
    • This is an advantage of DLSC jacquard over SLSC jacquard.
    • DLSC jacquard produces a semi-open shed.
    • Double Lift, Double Cylinder (DLDC) jacquard has two cylinders, one for odd picks and one for even picks, each carrying a pattern card.
    • A 400 capacity machine will have 800 hooks and 800 needles.

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    Description

    This quiz tests your understanding of jacquard loom calculations, including total ends, repeats, and harnesses per hook. It's an essential concept in textile engineering and fabric weaving.

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