This application claims the priority of German Patent Application No. 103 31 759 dated 14 Jul. 2003, the disclosure of which is incorporated herein by reference.
The invention relates to an apparatus on a draw frame for textile fibre slivers with a drawing system of successively arranged pairs of rollers comprising a bottom and a top roller in which a load can be applied to the top rollers.
During operation of a draw frame of the above-mentioned kind, the top rollers are pressed against the bottom rollers by weighted pressing elements in pressing arms. When operation is suspended, the bearings of the top rollers are relieved of the loading by the pressing arms and upon interruption to continuous operation the top output roller or the top output rollers are relieved of loading such that no or only slight pressure is exerted on the fibre slivers.
During operation, the pressing arms are closed and the pressing devices press the top rollers onto the associated lower rollers of the drawing system. When operation of the drawing frame is suspended, particularly for a longer time period, the pressure cylinders and hence at the same time the top rollers are relieved of load, so that the rollers (roundness) and their resilient coating are protected against deformation. When the pressing arms are pivoted open while the top rollers remain stationary on the lower rollers, the top rollers exert a pressure on the bottom rollers by virtue of gravity. Since the slivers are positioned between the top and bottom rollers, the top rollers, in their idle state, exert a pressure on the slivers. During operation, particularly at high sliver speeds of 1,000 m/min and above, the rollers heat up substantially. The fibres frequently contain substances that become sticky when heated, for example, honeydew in the case of cotton and lubricating agents in the case of synthetic fibres. When the draw frame is at a standstill for a relatively long period —especially for longer than the time required to exchange full for empty cans at the output end of the draw frame—for example, on sliver rupture, when exchanging empty for full cans at the input end of the draw frame, during operational disturbances and the like, the top output roller(s) in particular, at the roller nip with the bottom output rollers, press against the substances clinging to the fibres and the substances become sticky owing to the heat. The disadvantage of this is that the slivers stick firmly especially to the top roller or top rollers and, when operation resumes, are entrained by the rotating roller and wind undesirably around the roller. This causes considerable disturbance to operation, since the drawing system is immediately stopped and the wrapped-round sliver has to be manually removed. In particular, the incident can often not be immediately resolved, which leads to delays and thus to production losses.
In a known apparatus (DE 198 39 885 A1), at least one separately controllable pneumatic valve for the pneumatic cylinder is associated with the top output roller and/or the top output rollers and at least one adjustable carrier lever or similar for the top output roller is associated with the pneumatic cylinder. By pulling in the ram, the carrier lever is drawn up and with it, the associated top roller bearing. In order to realise two loading functions of the pressure cylinder, that is, a push function and a pull function, a complicated valve device with corresponding valve control (separately controllable pneumatic valve) is required.
It is an aim of the invention further to improve an apparatus of the kind described in the introduction, and to provide a draw frame which avoids or mitigates the said disadvantages and in which in particular the undesirable formation of windings is avoided or reduced.
The invention provides a draw frame for textile fibre slivers having a drawing system comprising:
Advantageously, the lifting arrangement comprises:
Advantageously, the lifting arrangement comprises first and second resilient loading elements for loading said first and second resiliently loaded elements.
When operation is interrupted, the bearing pressure of the top rollers on the fibre slivers is absent or substantially absent and, in particular, the top roller engages only slightly or not at all with the fibre material, so that heating of substances in the fibre material, and thus the adhesive effect, are avoided. The fibre slivers are thus effectively prevented from undesirably adhering to the rollers, so that entrainment upon re-start and hence the formation of a winding around the rollers does not occur. Because a resilient element, preferably a mechanical compression spring, is provided to lift the top roller bearing, a substantial structural simplification is achieved. Unlike the known apparatus, a separately controllable valve control for lifting the top roller is not present. A particular advantage is the fact that each time the top roller bearings are relieved of the pressure exerted by, for example, a pneumatic ram (that is, the pressure is reduced or removed), the resilient element automatically relaxes, and as a result, the top roller bearings are lifted from the bottom roller bearings including the top rollers from the bottom rollers.
Advantageously, at least one said resiliently loaded element is a driver element. At least one said loaded element is advantageously loaded by a spring, for example, a compression spring. Advantageously, as driver element an angle lever, angled plate or the like is provided. Advantageously, one angle arm of the driver element engages beneath the top roller bearing or the bearing stub. Advantageously, the free end of a resilient element, for example, compression spring, loads the driver element. Advantageously, a resilient element, for example, compression spring, is supported on a fixed bearing. Advantageously, the line of action of the ram and the line of action of at least one resilient element, for example, compression spring, run substantially axially parallel to one another. Advantageously, at least one resilient element, for example, compression spring, is tensioned in continuous operation. Advantageously, each time the pressing elements are relieved of loading, a said resilient element, for example, compression spring, relaxes. Advantageously, the relaxation of the resilient element, for example, compression spring, is effected automatically. Advantageously, lifting of the top roller bearings or the bearing stubs is effected upon extended interruption of continuous operation. Advantageously, lifting of the top roller bearings or the bearing stubs is effected within a short time. Advantageously, upon continuation of continuous operation, the loading of the top rollers and the tensioning of the resilient elements, for example, compression springs, are effected automatically. Advantageously, upon continuation of continuous operation, the loading of the top rollers and the tensioning of the resilient elements, for example, compression springs, are effected simultaneously. Advantageously, a 4-over-3 drawing system is present, the top roller nearest the output—viewed in the direction of travel of the textile fibre material—is relieved of loading. Advantageously, the top roller is a deflecting roller. Advantageously, at least one top output roller is lifted away from the bottom output roller. Advantageously, a spacing is present between the top output roller and/or the top output rollers and the fibre slivers. Advantageously, upon machine standstill at least one top roller is capable of being bought automatically out of contact with the fibres. Advantageously, the last top roller in the material running direction is capable of being brought automatically out of contact with the fibres. Advantageously, upon re-start of the machine the previously lifted roller is capable of being returned automatically into engagement under pressure loading. Advantageously, a mechanical element is provided as resilient element. Advantageously, adjustment devices, for example, threaded pins or the like, are provided for adjustment of the position of the driver element.
The invention also provides a draw frame for textile fibre slivers, having a drawing system comprising a roller to which in use a load can be applied, the load being relievable when the draw frame is not in operation, the draw frame further comprising a lifting arrangement for lifting said roller away from a second roller with which it is in co-operation during operation of the draw frame, when the load is relieved.
Moreover, the invention provides apparatus on a draw frame for textile fibre slivers with loading of the top rollers of the drawing system of successively arranged pairs of rollers comprising a bottom and a top roller, in which, during operation, the top rollers are pressed against the bottom rollers by weighted pressing elements in pressing arms, wherein the bearings of the top rollers, at standstill, are relieved of the loading by the pressing arms and the top output roller or the top output rollers is/are capable of being relieved of pressure on interruption to continuous operation so that no or only slight pressure is exerted on the fibre slivers, wherein respective resiliently loaded elements are associated with the bearings of at least one top roller and lift the top roller bearings when the pressing elements are relieved of loading.
a is a perspective view of pressing arm shown in
a is a front view, partly in section, of a top roller bearing loaded by a ram on one side and a bearing stub loaded by a tensioned spring, top and bottom roller being located one on top of the other with no gap between them;
b shows a the top roller bearing of
c shows in detail the spring-loaded angle lever shown in
a is a front view, partly in section, of a top roller bearing of the top roller of
b shows the top roller bearing relieved of loading by the ram and the bearing stub lifted with the relaxed spring, top roller and bottom roller (as in
c shows in detail the spring-loaded angle lever shown in
a shows a drawing system of a draw frame according to the invention in operation with the top rollers loaded, and
b shows the drawing system of
With reference to
Referring to
Referring to
In the embodiment of
According to
In operation, corresponding to
When operation is suspended, corresponding to
Referring to
Except where the opposite is apparent, the same reference numerals are used to indicate corresponding parts in each of the drawings
The invention has been described by the example of pneumatic pressing elements (loading elements). Alternatively, mechanical, hydraulic or electrical pressing elements for loading the top rollers 1 to 4 can be used.
In practice, many loops appear around the deflecting roller 1, usually caused by lubricating agents and adhesive particles present on the fibres. After an operational disturbance in the machine (sliver rupture, coiler can change or the like), the machine attendants are often not able to resolve such incidents immediately. The draw frame relieves the drawing system of loading after an interruption occurs, but the hot deflecting roller 1 lies on the fibres 5 under its own weight. If the deflecting roller 1 lies for an extended period on the sticky fibres 5, these adhere to the deflecting roller 1 and upon restart, the sticky fibres 5 wrap themselves around the deflecting roller 1. The measures according to the invention enable the deflecting roller 1 to be lifted by means of a resiliently loaded driver element 36a, 36b. By lifting the deflecting roller 1, the fibres 5 can no longer stick to the roller, and the pressure on the lower roller 1 is reduced, whereby the wrap-round tendency is considerably reduced. The reduction in the wrap-round tendency significantly increases the efficiency of the draw frame when sticky fibres are being processed, because operational disturbances and their elimination are reduced or avoided
Although the foregoing invention has been described in detail by way of illustration and example for purposes of understanding, it will be obvious that changes and modifications may be practised within the scope of the appended claims.
Number | Date | Country | Kind |
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103 31 759.7 | Jul 2003 | DE | national |