Simplex Frame and its Parts

The roving/Simplex frame is an intermediate machine between draw frame and ring frame the main objective of this machine is to convert sliver into thinner sliver for the convenience of subsequent processes. The sliver we obtain from draw frame is still thicker sliver which is not good for yarn manufacture. So the sliver thickness or the yarn count is reduced by this machine to the required level. But in this operation main drawback is that the reduction is somewhat so high and cannot be obtained from roller drafting mechanisms. The solution for this is to reduce the yarn count to a low level but not to the level required to the yarn manufacture which means the production of intermediate sliver which is called roving sliver.

The roving machine is complicated, liable to faults, causes defects, adds to production costs and delivers a product that is sensitive in both winding and unwinding. “Simplex is a necessary evil”, even than this machine is forced to use by the spinner for the following two reasons.Sliver is thick, the untwisted strand that tends to be hairy and to create a fly. The draft needed to convert this is around 300 to 500. Drafting arrangements of ring frames are not capable of processing this strand in a single drafting operation to create a yarn that meets all the normal demands on such yarns.

It is the final process of making yarn. The roving is drawn between rollers according to the count requirement and passed through ring travelers which are loosely engaged on rings to impart twist to the yarn and then the yarn is wound on bobbins. As the bobbins are full it will be removed from the ring frame and sent for auto cover.

Parts of Simplex and their Functions

Following are the various parts and their functions fo the Simplex Frame

Bottom steel fluted rollers

The bottom rollers are made of steel and are mounted on a roller stand.These are positively driven by the main gear transmission.For better carrying of the material in a forward direction, these rollers are fluted into

1. Axial fluted
2. Spiral/inclined fluted
3. knurled fluted

Nowadays axial flutes are replaced by inclined flutes which result in better gripping of fibers as well as fewer wears of top rollers.Knurled flutings are on those rollers on which apron revolves.

Top rollers

There are two parts of top rollers

1. Arber (top rollers without rubber cot)
2. Rubber cot

These are actually twin rollers having rubber cots for better gripping of fibers during drafting.ü Hardness of top rollers depends upon the type of material. Normally for cotton, less hardness is recommended as compared to polyester fiber.ü For polyester more hardness is better to avoid wear of the top rollers.(Rollers are replaced after 15-20 years).For better gripping, these rollers are ground after a certain period.So with the passage of time, the diameter of these rollers will be reduced and behind the limits, these can’t be used. Hence old cots are replaced by new cots With the result of the reduction of top roller diameter, arm pressure will be reduced which will result in less/undrafted material.With the result of grinding, a surface of top rollers become rough. Hence on the processing of sensory fibers, rough roller surface result in wrapping effect. To overcome this problem a chemical treatment is required which will smooth the surface.

Aprons

The upper aprons are short and made of synthetic rubber. The thickness of apron is about 1mm.Lower aprons are larger and made of same material as that of uppers.Aprons are used to support the material which is being drafted and ultimately to reduce the variation in the material i.e. material will be uneven.When a drafting force is applied, there is a chance of variation. So to reduce this variation, aprons are provided.In the main drafting, zone aprons are used for further control of the drawing sliver. In the zone, the number of fibers is less and they are given draft so that any floating fiber content would occur fabric defects and it has to be avoided.

Pressure Arm

Pressure is implemented on main drafting roller to improve the nip contact and higher nip. Since a high drafting is taken place, the possibility to make slippages is somewhat high. This is avoided and prevented to avoid long-term variations in subsequent processes.The top rollers are well pressed on bottom rollers by applying pressure through pressure arm.

Pressure depends upon raw material and volume.Adjustment of pressure may be same for each roller or vary from zone to zone (Main, back or front zone).In pressure, arm springs are used and somewhere pneumatic pressure is given.By applying more pressure, there are chances of fiber damaging while less pressure cause slippage, which will increase U%age of roving.
In cotton material, more the moisture content more will be the arm pressure required. More moisture content in sliver is due to more moisture content in cotton (8.9). More R.H% (58-63).

Cradle assembly

Consists of

• Cradle
• Top apron
• Steal roller
• Spacer
• Cradle spring

It supports the material during drafting and reduces the variation due to drafting force.Spacer size changes the distance between the aprons (bottom &top). For coarse material, bigger size spacer is used.Change of spacer size affects the U%age.

Flyer

A flyer is used to wind the roving on a bobbin and to impart twist into the roving revolving around the bobbin at a speed 700-1300 rpm.Flyer inserts twist. Each flyer rotation creates one turn in the roving. Twist per unit length of roving depends upon the delivery rate.

Turns per meter (twist)  = Higher levels of roving twist, therefore, always represent production losses in Roving frame and possible draft problems in the ring spinning machine. But very low twist levels will cause false drafts and roving breaks in the roving frame.False Twisters are used on the flyers to add a false twist when the roving is being twisted between the front roller and the flyer. Because of this additional twist, the roving is strongly twisted and this reduces the breakage rate.

The spinning triangle is also reduced which will reduce the fiber fly and lap formation on the front bottom roller.Because of the false twister, the roving becomes compact which helps to increase the length wound on the bobbin. This compactness helps to increase the flyer speed also.Apart from inserting twist, the flyer has to lead the very sensitive strand from the flyer top to the package without introducing false drafts. Latest flyers have a very smooth Guide Tube set into one flyer leg and the other flyer leg serves to balance the flyer.

The strand is completely protected against air flows and the roving is no longer pressed with considerable force against the metal of the leg, as it is in the previous designs. Frictional resistance is considerably reduced so that the strand can be pulled through with much less force.If we use high precision flyers, it will result in the form of following advantages:

1. Dynamic flyers ensure excellent yarn quality and free of fluff accumulation and fiber chocking.
2. Flyers are made from quality aluminum alloy, polished stainless steel tubes, and steel parts.
3. Computer generated aerodynamic profile ensures minimum air turbulence and noise.
4. To facilitate well twisted roving false twisters are specially designed and manufactured.
5. Minimum vibrations in the flyer are kept by high precision balancing at all rated speeds.
6. To maintain constant pressure, Pressers are made of heat treated special grade steel.
7. Higher return on investment on flyers.

Condenser

In Simplex machine two condensers are used in the drafting arrangement.The purpose of these condensers is to bring the fiber strands together.It is difficult to control, Spread fiber masses in the drafting zone and they cause unevenness.In Addition, a widely spread strands leaving the drafting arrangement leads to high fly levels and to high hairiness in the roving.The size of condensers should be selected according to the volume of the fiber sliver

Top & bottom cleaners

Cleaning is one another important aspect of drafting zone. Since the high draft is given to the sliver, short fibers can immune from the main flow of fibers and then may wind on rollers itself.If this process keeps happening the drafting capability of the rollers are effected through contact area and lose grip.Hence tow aprons are used to clean each and every roller during drafting. In this machine, two top and bottom cleaners are also used for the cleaning purpose.

Bobbin Rail

The bobbin rail is moving up and down continuously so that the coils must be wound closely and parallel to one another to ensure that as much as a material is wound on the bobbin. Since the diameter of the packages increases with each layer, the length of the roving per coil also will increase. Therefore the speed of movement of bobbin rail must be reduced by a small amount after each completed layer