Weaving Mechanisms Quiz

The warp yarns passing through the 1st heald frame form the bottom shed line.

The reversing mechanism allows the 1st frame to move up while the 2nd frame moves down, enabling continuous shedding.

Positive tappet shedding is defined as shedding where heald frames are raised and lowered by double cams.

<p>The tappet shaft provides the drive for the double cams that raise and lower the heald frames during the shedding operation.</p> Signup and view all the answers

<p>The rotary motion of double cams is converted into up and down motion of the heald frames.</p> Signup and view all the answers

<p>The clamp screw is used for the adjustment of the fork lever by moving it up and down.</p> Signup and view all the answers

<p>When the lower cam presses the treadle roller, the treadle lever moves toward the loom side, lowering the heald frame.</p> Signup and view all the answers

<p>The upper cam pressing the upper treadle roller causes the heald frames to move upwards.</p> Signup and view all the answers

<p>Moving the fork lever upward increases the shed opening, while moving it downward decreases it.</p> Signup and view all the answers

<p>Dobby shedding allows for a variety of weave designs to be produced more easily than crank shedding.</p> Signup and view all the answers

<p>Increasing the length of link rods raises the shed height, while decreasing it lowers the shed height.</p> Signup and view all the answers

<p>Dobby shedding involves more intricate mechanisms and settings, making it more complicated to operate and maintain.</p> Signup and view all the answers

<p>It allows for the creation of intricate weave designs with continuous patterns without restrictions.</p> Signup and view all the answers

<p>In water jet looms, dobbies are mounted in the upper position to avoid contact with water.</p> Signup and view all the answers

<p>Dobby shedding mechanisms typically incur higher initial and maintenance costs compared to simpler shedding systems.</p> Signup and view all the answers

<p>Dobby shedding looms tend to operate slower than crank and tappet/cam shedding systems.</p> Signup and view all the answers

<p>Increasing the number of cams raises the force (R) in the system.</p> Signup and view all the answers

<p>The maximum number of cams that can be installed is between 8 and 12.</p> Signup and view all the answers

<p>Negative tappet shedding occurs when heald frames are lowered by single cams and returned by external devices like springs.</p> Signup and view all the answers

<p>Heald frames are raised and lowered by double cams.</p> Signup and view all the answers

<p>Reversing media, such as springs or pulleys, returns the frames to their original position.</p> Signup and view all the answers

<p>The treadle lever has one end as a fulcrum connected to point 'F' and the other end linked to the bottom of the heald frames via a connecting rod.</p> Signup and view all the answers

<p>When the tappet cam presses the treadle lever, the connected heald frame moves down while another frame rises due to the reversing mechanism.</p> Signup and view all the answers

<p>The rotary motion of tappet cams is converted into the up and down motion of heald frames.</p> Signup and view all the answers

<p>Mechanical Dobbies and Electronic Dobbies.</p> Signup and view all the answers

<p>Drive Mechanism, Selection Mechanism, and Lifting Mechanism.</p> Signup and view all the answers

<p>It checks the weave design information from the punched card, pegged lattice, or electronic means.</p> Signup and view all the answers

<p>It has two working knives, two hooks, and two feelers for each heald frame, allowing it to select two picks at a time.</p> Signup and view all the answers

<p>Case 4 occurs when there are pegs for both Feelers (F1 and F2).</p> Signup and view all the answers

<p>The lifting mechanism operates the lifting and lowering of the heald frames.</p> Signup and view all the answers

<p>The drive mechanism provides the necessary motion through either reciprocating knives or rotary components/cams.</p> Signup and view all the answers

<p>It transmits motion based on the weave design information it receives.</p> Signup and view all the answers

<p>Positive dobbies can run safely at higher speeds due to better control of the shedding mechanism.</p> Signup and view all the answers

<p>The KSLP Dobby employs a single acting or single lift mechanism, which performs shedding after every pick.</p> Signup and view all the answers

<p>Cylinders C1 and C2 drive the vibrator gear, enabling the movement of the heald frames during shedding.</p> Signup and view all the answers

<p>At the initial position, the vibrator gear is down with a one-tooth gap at the top and a three-tooth gap at the bottom.</p> Signup and view all the answers

<p>The selection mechanism determines whether to lift a heald frame based on the positioning of the vibrator gear.</p> Signup and view all the answers

<p>Both cylinder gears have teeth on only half of their circumference, with the other half left blank.</p> Signup and view all the answers

<p>Cylinder C1 is rotated clockwise, while cylinder C2 is driven counterclockwise.</p> Signup and view all the answers

<p>The gaps on the gears ensure that the drive mechanism functions correctly by providing necessary clearance.</p> Signup and view all the answers

<p>Rotary dobbies use rotary elements with cam units instead of reciprocating knives, allowing for different shedding methods.</p> Signup and view all the answers

<p>The components are the cam itself, ball bearings, coupling ring, and moveable key.</p> Signup and view all the answers

<p>An electronic rotary dobby uses solenoids or electromagnets for movement, while a mechanical dobby relies on physical ratchets.</p> Signup and view all the answers

<p>The moveable key engages with the coupling ring to enable the transfer of rotation necessary for lifting the heald frames.</p> Signup and view all the answers

<p>Joseph Marie Jacquard invented the Jacquard shedding mechanism in 1801.</p> Signup and view all the answers

<p>Crank shedding, tappet shedding, and dobby shedding are other types of shedding mechanisms.</p> Signup and view all the answers

<p>The microprocessor reads the weaving design and signals the solenoids to lift the frame as required.</p> Signup and view all the answers

<p>In an electronic rotary dobby, the ratchet is moved by solenoids controlled by electrical signals.</p> Signup and view all the answers

As the slope of a cam's contour increases, the force required also increases. To avoid excessive force, the maximum cam contour should be minimized.

Due to increased force and wear issues, practical cam systems usually have no more than 8-12 cams per shaft.

Heald frames are moved up or down by the cam, and then returned to their original position by external devices (like springs).

Heald frames are raised and lowered directly by double cams.

The mechanism (springs, pulleys, etc.) that returns the heald frames to their starting positions.

Negative shedding mechanisms are powered by the bottom shaft.

The rotary motion of tappet cams is transformed into the up-and-down motion of heald frames.

A lever system that connects to the heald frames and is activated by a roller or bowl connected to the tappet cam.

Two cams mounted on a shaft used to move heald frames in a weaving machine.

A lever that connects to double cams and moves heald frames up and down.

The upward and downward motion of heald frames to create the shedding pattern in weaving.

The process of opening and closing the shed (space between warp yarns) to allow passage of the weft yarn in weaving.

The longitudinal yarns running from the top to the bottom of the textile.

The yarn that is woven across the warp yarns to create the fabric.

The shaft that rotates, driving the double cams in positive tappet shedding.

Adjusting the fork lever with a clamp screw changes the opening of the shed.

Increasing the length of link rods with a lock screw adjusts the shed's height.

A versatile shedding method, common for 12-32 heald frames, enabling many patterns.

Dobbies are typically mounted at the bottom, except in water jet looms where they are mounted at the top.

Dobby shedding can create a virtually unlimited number of picks in a pattern repeat.

Easy pattern changes, variety in designs, and unlimited picks per pattern repeat.

More complex mechanisms, higher initial costs, higher maintenance cost,and slower operation than other methods.

The mechanical components in a loom (like shafts, levers, frames), that manage shed openings and pattern changes.

Dobbies are categorized based on their selection method: mechanical (using pegs or cards) and electronic.

A type of dobby that uses mechanical methods (pegs or punched cards) to select which threads to lift.

A type of dobby that uses electronic control systems to select lifting threads.

The mechanism in a dobby that controls warp thread lifting in weaving, consisting of drive, selection, and lifting components.

A type of double lift negative dobby, which is a standard for modern double lift mechanisms.

The part of the dobby that determines which warp threads to lift on each pick (or cycle).

Dobby design that lifts threads in pairs in a process.

A punched card used to program the exact patterns for lifting and lowering warp threads in dobby mechanisms.

A type of dobby shedding where the heald frames are moved directly up and down by the dobby mechanism, eliminating the need for spring reversing motions.

An early type of positive rotary dobby mechanism that is no longer used due to its single-acting nature.

Short for Knowles Single Lift Positive Dobby, a single-acting dobby that lifts the heald frames after every pick.

A gear in a Knowles dobby that is connected to the heald frames and rotates to drive the shedding mechanism.

Two gears in a Knowles dobby (C1 and C2) that rotate in opposite directions to drive the vibrator gear.

An area on the circumference of the vibrator gear and cylinder gears that lacks teeth, preventing engagement.

The starting position of the gears in a Knowles dobby where the vibrator gear is down and the cylinder gear C1 cannot engage.

The part of a dobby that determines which heald frames should be lifted or lowered to create the shedding pattern.

A type of dobby that uses rotating cams to lift heald frames, creating a shed for the weft yarn.

A small, compact unit within a rotary dobby that controls one heald frame. It includes a cam, ball bearings for smooth rotation, a coupling ring, and a moveable key.

A key that can be moved by a ratchet, connecting the cam to the connecting rod, and ultimately lifting the heald frame.

A mechanism controlled by the weave design, moving the moveable key to engage the coupling ring and lift the heald frame.

A type of shedding where multiple harnesses are used to create the shed, instead of heald frames.

A group of threads or yarn that is used to raise and lower warp threads in Jacquard shedding.

Instead of using heald frames, Jacquard shedding relies on harnesses to control the warp yarns and create the shed.