Needle bar for chain drawing frame

Description

The invention concerns a faller bar for a chain drafting system, in particular a textile machine. It further relates to a chain drafting system with a number of such faller bars. A chain drafting system having a number of such faller bars is used in machines for combing, post-combing and spinning preparatory processes.

One such faller bar, often also referred to as a disposable faller bar, is the subject, for example, of US 2005/0218899 A1. With this known faller bar, a series of pins is surrounded by a retaining casing, which also surrounds a support bar, having a wall thickness of just 1 mm at least in parts. The diameter of the support bar may vary between 6 mm and 8 mm. When the support bar has a diameter of 8 mm, the resulting faller bar has a total diameter of at least 10 mm, so that such a faller bar is no longer suitable for use in standard chains with a chain spacing of 9.525 mm.

The object of the invention is to present a faller bar that is particularly suitable for a chain drafting system, in particular one having a chain spacing of 9.525 mm.

According to the invention, this object can be met by the faller bar as disclosed in claim 1. Furthermore, the faller bar has a support bar having a bar diameter of 5.9 mm to 6.1 mm, whilst the wall thickness of the casing in the region having the thinnest wall thickness is between 1.4 mm and 1.8 mm.

The bar diameter should preferably be 6.0 mm. With this preferred bar diameter, the wall thickness of the casing, at least in the thin-walled zone, is preferably 1.6 mm, to allow for the, at least, slight shortfall in the chain spacing of a chain drafting system carrying a number of such faller bars.

The chain spacing refers to the distance between the central longitudinal axes of adjacent faller bars, such as are used min a chain of a chain drafting system of a textile machine.

In a preferred embodiment, such a faller bar has a distance between the longitudinal axis of the pins and the longitudinal axis of the support bar of more than 2.15 mm and, in particular, 2.75 mm. The resulting greater pin distance, i.e. the closer arrangement of the longitudinal axis of the pins on the faller bar to a take-off roller of the chain drafting system in the delivery zone around the fibrous material to be processed, improves the quality of the fiber sliver.

The advantages of this invention are in particular that a faller bar having a bar diameter and a casing thickness in the ranges mentioned has a comparatively low total weight and is therefore particularly lightweight. Furthermore, a faller bar having such an arrangement is flexible, in that the forces acting on the pins during normal use are reduced. In the zone where the greatest deflection occurs, the faller bar can be supported against the adjacent faller bar in the chain drafting system, whereby the forces produced are transferred gently to the chain and to the drive acting on it.

Some examples of different embodiments of the invention will now be presented in more detail, with the aid of diagrams. The following are shown:

FIG. 1 a side view and a view from above of a faller bar for a chain drafting system,

FIG. 2 a cross-section through the faller bar along line II-II as shown in FIG. 1,

FIG. 3 two faller bars as shown in FIG. 2 and arranged in a chain, and

FIG. 4: a cross-sectional view of the end of a chain drafting system with a number of faller bars arranged in chains, together with the arrangement of rollers for transporting a fiber sliver.

Corresponding components are given the same reference symbols in all of the diagrams.

FIG. 1 shows two different views of a faller bar 1 for a chain drafting system 8 (FIG. 4). The faller bar has a support bar 2, one end of which is formed as a shaft 2a. At the opposite end to the shaft 2a, it is fitted with a bearing bore 2b. The support bar 2 is covered with a casing 4, which is formed as a rib 4b on one side. A number of pins 3 is arranged in a row along the longitudinal axis 6 of the support bar. The casing 4 consists of a plastic material, which is applied by a spraying process while the pins 3 are being mounted onto the support bar 2. A pair of guide grooves 7 is in each case formed in the section of the support bar 2 between shaft 2a and rib 4b.

FIG. 2 shows a cross-section through a faller bar. The support bar 2, which is characterized by a diameter d, lies inside the cross-section. In relation to the longitudinal axis 6 of the support bar, the thinnest zone 4a of the casing 4 lies opposite to the part of the casing 4 that is formed as rib 4b. This thin-walled zone 4a of the casing 4 extends at least over half the bar circumference of the faller bar 1, i.e. at least over the semi-circular curved region of the faller bar 1, which lies under the central line M, running through the longitudinal axis 6, of support bar 2, as shown in the diagram.

The distance between the longitudinal axis 5 of each pin and the longitudinal axis 6 of the support bar will subsequently be referred to as the pin distance, and is the result of the difference between radius D/2 of the faller bar 1 and the half thickness m/2 of rib 4b. At a rib thickness of m=3.7 mm, in a preferred embodiment, the pin distance is a=2.75 mm, when the diameter of the support bar is d=6.0 mm and the casing has a wall thickness of 1.6 mm in the thinnest-walled zone 4a.

FIG. 3 shows the arrangement of two faller bars 1 in a chain drafting system 8 with a chain (not shown). The distance t between the longitudinal axes 6 of the support bars corresponds to the so-called chain spacing in the chain used in the chain drafting system 10. The chain spacing of the preferred chain used is t=9.525 mm.

FIG. 4 shows the arrangement of a number of faller bars 1 in a chain drafting system 8 of a textile machine having two chains 9. The letter A denotes the feed direction of the chain drafting system 8. At the end of the chain drafting system 8 are located a take-off roller 10 and two further rollers 11, 12 for feeding the material being processed by the textile machine, which is not shown in more detail.

The pins 3 of the faller bars 1 used in the chain drafting system 8 penetrate into the material being processed up to the delivery point v in front of the take-off roller 10. By increasing the pin distance from 2.15 mm to 2.9 mm, the delivery width v in front of the take-off roller 10 is decreased by 0.75 mm. This means that the pins 3 of the faller bars 1 are in contact with the material to be processed for a longer period of time and/or for a greater distance, which in turn improves the quality of the fibrous material being processed.

LIST OF REFERENCE SYMBOLS

• 1 faller bar
• 2 support bar
• 2 shaft
• 2 bearing bore
• 3 pin
• 4 casing
• 4 zone of the casing having the thinnest wall
• 4 rib
• 5 longitudinal axis of the pin
• 6 longitudinal axis of the support bar
• 7 guide groove
• 8 chain drafting system
• 9 chain
• 10 take-off roller
• 11 additional roller
• 12 additional roller
• A feed direction
• D total diameter
• M central line
• a distance, pin distance
• d diameter of the support bar
• m rib thickness
• t chain spacing
• v delivery width