Title: Method and apparatus for treating textile consisting of yarns.
The invention relates to a method for treating textile consisting of yarns, such as refining or cleaning, the textile being treated while held in a plane for treatment. The invention also relates to an apparatus for the use of this method. Such an apparatus is known from "Penn Linen Goes In Dirty On
One End, Comes Out Finished On The Other", Textile Rental, Clyde E. -Blaco, April 1996, pp. 38 - 44. In this publication, an apparatus is described, also called a flatbed washer, through which cloths of textile, such as soiled sheets, are fed at a uniform speed. During the feed-through over an assembly of feeding rollers, the textile is kept flat and is cleaned by passing it through consecutive baths with cleaning liquid and rinsing liquids. Finally, the textile is dried and pressed.
During the treatment of textile, transport of chemicals and/or dirt between the textile and the surrounding liquid takes place. It is important that the velocity of this transport be high; at low transport velocity, the treatment of the textile will take more time. Further, with types of textiles where the dirt can penetrate deeply into the yarns, cleaning will take more time than with types of textiles in which the dirt cannot penetrate that deeply. In the apparatus described hereinabove, the transport velocity is increased by treating the textile with a high pressure spray apparatus. Thus, the cleaning liquid obtains a higher flow rate relative to the textile yarns. With a greater passage of cleaning liquid, the dirt will be carried along more rapidly. By using this technique, the transport velocity in the yarns will not be raised to a satisfactory level. The object of the invention is to improve the method described hereinabove, so that the transport of chemicals and/or dirt can take place considerably faster than can be achieved with the above-mentioned method. Such an improvement is intended to yield a quicker and better treatment
result than is possible with the current technique. Further, the object of the invention is to provide an apparatus suitable for the use of such a method. This object is achieved with a method according to the preamble, wherein the yarns of the textile are subjected to a controlled stretch, after which relaxation of the yarns takes place. By stretching, the volume of the yarns in the textile decreases, so that the treatment liquid is pressed out of the textile, which, upon relaxation of the yarns, is re-absorbed. On a microscale, use is made of the sponge action of the textile, while the elasticity of the yarns is a determining factor which determines the extent of stretch to be applied.. It will be clear that the invention can also be used with textile folded in a number of layers to a flat plane. Further, it will be clear that soaking the textile in treatment liquid can be achieved by passing the textile through treatment liquid, but also by spraying the textile or sprinkling it with treatment liquid. For an optimal sponge action, it is preferred that the stretch has a direction which is substantially in φe plane of the textile. It is further preferred that the stretch has a frequency which is as high as possible, though not higher than in accordance with the possibility of the yarns to sufficiently relax. Such a frequency, therefore, relates to the duration of a cycle of stretching and subsequent relaxation of the textile. It is self-evident, that this preferred frequency is strongly dependent on the textile to be treated. It appears, in practice, that for most types of textile, the stretch has a frequency with a value ranging from 0.5 - 50 Hz, preferably ranging from 1 - 10 Hz. Additionally, it is advantageous to use the method such that the stretch has an amplitude which is set as high as possible, though not higher than in accordance with the possibility of the textile not to become damaged. In practice, it appears that the stretch has an amplitude with a relative value ranging from 0.1 - 5%, preferably from 0.5 - 2% of the dimension of the textile. To promote relaxation taking place while the dirt can be removed by the treatment liquid, it is preferred that the duration of time the textile is held in
the treatment liquid and the duration of time the textile is stretched, overlap. The method according to the invention is advantageously used in an apparatus comprising a guiding device arranged to treat textile consisting of yarns while held or folded ih a plane, and stretching and relaxation means for applying a controlled stretch on the yarns. Such stretching and relaxation means are intended for applying a controlled stretch on the yarns of the textile, after which, through release, relaxation of the yarns takes place. The stretching and relaxation means can be disposed at least partly in treatment liquid. The guiding device can comprise two nets with longitudinally oriented diamond-shaped mazes, which keep the textile together on opposite sides. The guiding device ςan also comprise two or several guiding bands. The guiding bands can maintain the textile in a direction transverse to the path of transport. The stretching and relaxation means can comprise modulating means for modulating the length of the transport path. This modulation has as a consequence that the textile follows a transport path which varies in length. As a result, a controlled stretch is applied to the yarns of the textile, after which, through release, relaxation of the yarns takes place. The modulating means can comprise at least one guiding roller having a shape such that the textile is passed around the guiding roller in an eccentric movement. On the at least one guiding roller, a cam-shaped element can be disposed. The cam- shaped element can have a shape such that the textile in the transport path, at and in front of the cam-shaped element, lies clear of the guiding roller, while, after further rotation, the textile substantially abuts the guiding roller. With such a shape, it can be achieved that during rotation, apart from the effect, intended by the invention of a controlled stretching and relaxation of the yarns, also a transversal flow is induced, in that water enclosed between the plane of the transport path and the cam-shaped element, is pressed through the textile. As a result, the transport velocity mentioned above can increase even more.
In a further preferred embodiment, the cam is designed such that the cloth can perform a movement over the guiding roller between a position situated radially inward and a cam position, while forming a space which is defined by the cloth and wall parts of the guiding roller extending between positions located radially inwards on opposite sides of the cam and the cam position. Thus, the above-mentioned pressing action is further enhanced. Several cams can be provided on the guiding roller at a relatively large distance from one another. Preferably, a single cam is provided on the guiding roller. In this case, an optimal combination of stretching and relaxation of the textile is achieved, as well as the earlier-mentioned pressing action of treatment liquid through the textile.
The at least one guiding roller can also rotate around an eccentrically located axis. The at least one guiding roller can be provided with a cylindrical body part having disposed therearound a substantially freely rotatable outer surface. With such an outer surface, wear of the textile as a result of friction between the guiding roller and the textile cloth can be reduced and the stretching frequency is independent of the speed of the cloth.
Yarns in this context is at least understood to mean one or more textile fibres, preferably formed into a strand. A textile cloth comprises a fabric of such yarns.
The invention will be elucidated with reference to the drawing. In the drawing:
Fig. la is a schematic set-up of a test set-up, in which an eccentric guiding roller is entirely disposed in water; Fig. lb is a schematic set-up of a test set-up, in which an eccentric guiding roller is partly disposed in water;
Fig. lc is a schematic set-up of a test set-up, in which an eccentric guiding roller is disposed outside the water;
Fig. 2 is a graph showing the measuring results of the set-ups of Figs, la - lc;
Fig. 3 shows a few advantageous embodiments of a guiding roller with an eccentric shape;
Fig. 4 represents how the textile is guided along a guiding roller with a cam-shaped element; Figs. 4al-6 represents an animation of a preferred embodiment of a cam-shaped element;
Fig. 5 shows some advantageous embodiments of a guiding roller, which applies a controlled stretch to the textile cloth by means of a vibrating movement; Fig. 6 shows some advantageous embodiments of a guiding roller constructed from segments extending in the longitudinal direction thereof;
Fig. 7 shows a preferred embodiment of an apparatus according to the invention;
Fig. 8 shows another preferred embodiment of an apparatus according to the invention;
Fig. 9 shows another preferred embodiment of an apparatus according to the invention;
Fig. 10 shows a further preferred embodiment of an apparatus according to the invention. The set-up of Fig. 1 copies the action of a washing compartment, such as these can be used in practice, in plurality, connected in series in a full width washer for continuously washing, rinsing or impregnating webs of textile in the textile refining industry. In the set-up, the invention is used. The installations 1 in Figs, la - lc will presently be briefly discussed separately, corresponding parts having corresponding reference numerals.
In Fig. la, the installation 1 consists of a reservoir 2 which is filled with water. The water surface is indicated with reference numeral 3. In the reservoir, a guiding roller 4 is disposed, along which a continuous, single, flat strip of fibrous textile 5 is guided. The strip of textile 5 follows a path through the installation 1, in that it is guided over the tensioning roller 8 in the
direction of guiding rollers 6. The tensioning roller 8 maintains the textile strip 5 at a tension. The strip of textile 5 is squeezed out between pressure roller 7 and tensioning roller 8. On the guiding roller 4, a cam-shaped element 9 is provided. The water surface 3 extends amply above the guiding roller 4, which is, therefore, entirely disposed in the water.
In Fig. lb, the installation 1 consists of a reservoir 2 filled with water. The water surface is indicated with reference numeral 3. In the reservoir, a guiding roller 4 is disposed, along which a continuous, single, flat strip of fibrous textile 5 is guided. The strip of textile 5 follows a path through the installation 1, in that it is guided over the tensioning roller 8 in the direction of guiding rollers 6. Tensioning roller 8 maintains the textile strip 5 at a tension. The strip of textile 5 is squeezed out between pressure roller 7 and tensioning roller 8. On the guiding roller 4, a cam-shaped element 9 is provided. The level of the water surface 3 is chosen such, that the guiding roller 4 is partly disposed in the water.
In Fig. lc, the installation 1 consists, once more, of a reservoir 2, filled with water. The water surface is indicated with reference numeral 3. In the reservoir, a guiding roller 10 is disposed, along which a continuous, single, flat strip of fibrous textile 5 is guided. The guiding roller 10 is located completely under the water surface 3. The strip of textile 5 follows a path through the installation 1, in that it is guided along the guiding roller 11 over the tensioning roller 8 in the direction of guiding rollers 6. The tensioning roller 8 maintains the textile strip 5 at a tension. The strip of textile 5 is squeezed out between pressure roller 7 and tensioning roller 8. On the guiding roller 11 a cam-shaped element 12 is provided.
In this manner, in Figs, la- c a set-up is described in which, in three different manners, on the textile cloth, a controlled stretch is applied.
In Fig. la, the controlled stretch according to the invention takes place by providing the guiding roller 4 disposed in the water reservoir 2 with a cam-shaped element 9. Upon rotation of the guiding roller 4, this cam-shaped
element 9 will stretch the textile cloth 5 somewhat, after which the textile cloth 5 relaxes again when the cam-shaped element 9 has rotated further. Stretching the textile 5, therefore, takes place with the rotation frequency of the guiding roller 4, the degree of stretching being determined by the size of the cam-shaped element 9. For different choices, this frequency has values ranging between 0.5 Hz and 10 Hz. Stretching the textile cloth 5 takes place when the cloth is passed, entirely under water, along the rotating guiding roller 4.
In Fig. lb, the same set-up as in Fig. la is used, however, with a lowered water surface 3, so that the guiding roller 4 partly extends above the water. As a result, stretching the textile cloth 5 takes place partly outside the water.
Owing to the cam-shaped element 12 in Fig. lc being provided on the guiding roller 11, instead of, as is the case in Fig. la and lb, on the guiding roller 10 disposed in the water, the stretching of the textile cloth 5 takes place entirely outside the water.
The efficiency of the controlled stretching by means of the cam- shaped element 9, 12 can be tested in the different set-ups la-lc, by measuring the rate at which a salt solution, in which the textile cloth 5 is soaked, is rinsed out of the cloth during a washing treatment, in a washing treatment of the textile cloth 5 with a controlled stretch according to the invention, as compared to a washing treatment without use of such a controlled stretch. For this comparison, for all set-ups la - lc, a reference measurement was carried out, the cam-shaped element 9, 12 not being provided on the guiding roller 4 or the guiding roller 11.
The rinsing rate of the salt can be determined by measuring the salt concentration in the textile. This measurement is carried out with the aid of a measuring cell 13, with which the conductivity of the textile 5 can be determined. The conductivity is proportional to this salt concentration. According as the thus determined rinsing rate of the salt from the textile cloth
5 proves to be higher, the transport velocity of salt penetrated into the yarns to the surrounding water will have increased, and the efficiency of washing is greater. In this respect, it is important that the other factors influencing the rinsing rate are kept constant. These factors are, inter alia, the temperature, the tension on the textile, the type of textile and its weight.
The speed with which the textile cloth is passed over the guiding rollers is also a determining factor for the transport velocity. For that reason, in the set-ups la-c, measurements have been carried out for different cloth speeds, viz. at a speed of 30, 60 and 90 m/min. The results of these measurements are to be found in the graph of Fig. 2.
Series 1, represented in the graph by the line connected with the square symbols, indicates the measuring results of the set-up, represented in Fig. la, series 2, represented in the graph by the line connected with the diamond-shaped symbols, indicates the measuring results of the measurement set-up represented in Fig. lb, and series 3, represented in the graph by the fine connected with the circular symbols indicates the measuring results of the set-up represented in Fig. lc. In Fig. 2, the speed of the textile in m/min is plotted against the relative change of half-life, indicated in percentages. A positive relative half-life therefore indicates an improved effect as a result of the use of the controlled stretching of the textile cloth. From Fig. 2 it appears that for all speeds of the cloth an improvement occurs. The largest relative improvement was achieved at a cloth speed of 30 m min, with a s-^t-up as represented in Fig. la. It is possible that this, apart from the effect resulting from the controlled stretch, can be explained by additional transversal flows through the textile cloth 5, which occur through inclusion of water between the cam-shaped element 9 and the wall of the guiding roller 4, during a revolution of the guiding roller 4. Generating such transversal flows can also be used per se, without frequent stretching of the yarns, to increase the speed of transport. The half-life decreases for all set-ups by about 20% on average, i.e. the time in which the concentration of the salt solution is reduced by half,
decreases by approximately 20%. This means that in 80% of the time, a comparable cleaning effect is obtained. The residence time of the textile in the gashing apparatus can therefore be reduced by 20%.
Referring to Fig. 3, a few advantageous embodiments are represented of an eccentric-shaped guiding roller. In Fig. 3a, a guiding roller 14 is represented which rotates around an eccentrically located axis 15. The guiding roller 14 has a cylindrical body part 14a and is bearing-mounted in a freely rotatable outer sleeve 14b to reduce wear on the textile and to enable the stretching frequency to be independent of the speed of the cloth. In Fig. 3b, a guiding roller 16 is represented with an elliptical diameter, with a short axis d and a long axis D. In Fig. 3c a cam-shaped element 18 is provided on the cylindrical guiding roller 17. The cam-shaped element 18 has a shape which may or may not be cylindrical, of a diameter such that the desired stretch in the textile web can be brought about. In Fig. 3d, the diameter of the guiding roller 19 can vary with a preferred frequency between a smallest distance d and a largest distance D.
With reference to Fig. 4, a cross section is represented of a guiding roller 50 with a cam-shaped element 53. Two positions are represented in the respective Figs. 4a, 4b and 4c, wherein the cam-shaped element has rotated through an angle β, γ, respectively, wherein γ > β > 0. In the first position, represented in Fig. 4a, the cam-shaped element 53 only just engages the transport path of the textile 5, represented by the cam top 54. Upon continued clockwise rotation of the cam-shaped element, the cam top 54 is moved down in the direction of the arrow x. The textile at and in front of the cam top 54 thus follows a circular arc with an increasing radius, so that, in that part, the length of the transport path is increased. The fabrics of the textile path 5 are thereby elongated. Additionally, a second effect occurs, which is indicated with the arrow y in Fig. 4a. Due to the cam-shaped element 53 rotating further, the textile is moved outwards in the direction of the arrow y. As a result, when the guiding roller 50 is disposed under water, a transversal flow in opposite
direction through the textile will be generated. This transversal flow can contribute to the increase of the velocity of transport as well as to the earlier described effect of the controlled stretching of the textile. In Fig. 4b it is represented how, when the guiding roller 50 has rotated over an angle β, the strip of textile 5 in the portion in front of the cam top will be moved inwards in the direction of the arrow y'. During this inward movement, at and in front of the cam top 54, the textile, lying clear of the guiding roller 50, will enclose a part of the treatment liquid 52 (hatched in Fig. 4b) between the textile 5 and the guiding roller 50. Upon still further rotation of the guiding roller 50, represented in Fig. 4c, whereby the guiding roller 50 has rotated over an angle γ relative to the position represented in Fig. 4a, the textile 5 will substantially abut against the guiding roller 50 again. Then, only relatively little treatment liquid is present between the guiding roller 50 and the textile 5, which is represented in Fig. 4c by the hatched part 55. As a consequence, in the transition from Fig. 4b to 4c, the treatment liquid 52 will have been pressed through the textile, which will also contribute to the increase of the velocity of transport. In Fig. 4c, it is also indicated how the length of the transport path of the textile 5 is reduced in the direction of the arrow x'. The textile at and in front of the cam top 54 then follows a circular arc with a decreasing radius, so that the length of the transport path is decreased in that part. As a result, in this part, the fabrics of the textile 5 can relax.
In further illustration of the effect described in Fig. 4, in Figs. 4al-6, a simulation is represented of the reception and the release of the cloth by a cam disposed on a guiding roller. In Fig. 4al, the cam is situated in front of the position where the cloth is received by the guiding roller; in Fig. 4a2, the cam is at this position; and in Fig. 4a3, the cam is in a position, wherein the cam is enclosed by the cloth and the guiding roller.
When the textile contacts the cam, in the transition of Fig. 4al to Fig. 4a2, at the front side of the cam, a space is enclosed which is defined by the circumferential surface of the cam and the guiding roller on one side and
the cloth on the other side. Due to the guiding roller rotating at a given speed, during the enclosure of this space, an increase in pressure will occur in this space, in that, through the rotation of the roller, liquid is pressed into the space formed. This pressure generates locally a higher transport velocity of the licjuid through the fabrics.
Simultaneously, in the transition from Fig. 4al to 4a2, the cloth is pushed outward in radial direction by the movement of the cam, thus generating a transversal flow in the cloth part behind the cam. In the transition from Fig. 4a2 to 4a3, the cloth part lying clear of the guiding roller, moves radially inward while enclosing liquid, and then abuts over a part of the guiding roller, so that in the space defined by the circumferential surface of the cam and the guiding roller and the cloth, an increase in pressure will occur, so that a higher transport velocity of the liquid through the yarns is brought about. In Fig. 4a4, the cam is situated at the bottom of the roller and tensions the cloth on both sides of the roller, so that, in the longitudinal direction of the cloth, the tensile force on the cloth is increased. Thus, a stretching force is applied on the fibers of the cloth. Subsequently, in Fig. 4a5, the cloth is moved radially outward again and the enclosed liquid is released in front of the cam. Upon further rotation of the cam to the position of
Fig. 4a6, the cloth moves inward, so that, once more, a pressing-effect occurs, the reverse of Figs. 4al - 4a3. It is noted that the above-described effect occurs with a cam provided on a guiding roller, the roller having an outer surface with a radially more outward part which forms the cam, which cam, in the circumferential direction, Hnks up with at least a part of the outer surface situated radially inwards and which, in use, forms a chamber which is defined by the outer surface and the cloth. The cam is designed such that the cloth, while increasing and reducing the length of its path, can make a movement over the guiding roller between the part situated radially inward and the cam position, while forming a space which is defined by the cloth and wall parts of
the guiding roller extending between positions located radially inwards on both sides of the cam and the cam position. Several cams can be provided on the guiding roller at a relatively large distance relative to each other. When too many cams are present, insufficient stretching and relaxation of the cloth takes place and the cloth cannot follow the circumferential path situated radially inward. Preferably, therefore, a single cam is provided on the guiding roller.
Referring to Fig. 5, a few advantageous embodiments are represented of a guiding roller, which, by means of a vibrating movement, applies a controlled stretch on the textile cloth. In Fig. 5a, the guiding roller 20 can move the textile with a preferred frequency in the longitudinal direction of the guiding roller, which longitudinal direction is indicated with the arrow P. In Fig. 5b, the guiding roller 21 is driven by a stepping motor (not shown), which can have the guiding roller carry out a stepwise rotation. This stepwise movement is visualised by means of the interrupted arrow Q. In Fig. 5c, in a textile web 5, stretch according to the invention is introduced by means of a knife or guiding roller, making an up and down movement. The same stretch can also be generated by means of a jet flow 51 of water or air, which is modulated with a preferred frequency, as represented in Fig. 5d. With reference to Fig. 6, a few advantageous embodiments are represented of a guiding roller built up from segments extending in the longitudinal direction thereof. In Fig. 6a, the guiding roller 22 is built Up from longitudinally extending segments 23, 23', 23", having mutually different eccentric dimensions. In Fig. 6b, the guiding roller 24 is built up from segments 25, 25' 25" extending in its longitudinal direction, while the segment axes 25 have a small angle α relative to one another. This angle α is, maximally, 30°. Since these segments are in contact with the textile surface, the contact surface is stretched over its breadth, following the movement paths of the eccentrically situated segments, is stretched over its breadth.
With reference to Fig. 7, a preferred embodiment is represented of an apparatus 26, provided with guiding surfaces disposed in a path to be travelled by the textile 28 in the direction 26, so that the textile, while being transported through the apparatus, is thereby kept in a plane at all times. For clarity's sake, of the apparatus, only the guiding path of the textile 28 is represented. This guiding path is determined by guiding surfaces consisting of two nets 27, 29 with diamond-shaped mazes oriented in the longitudinal direction. The nets can keep the textile 28 together in a plane in the transport path of the textile. Thus, the textile 28 follows a path, starting at the input 31, over guiding rollers 32, to the output 33. The nets are respectively led back on the two sides of the transport path over a number of guiding rollers 34, so that they are circulated continuously. The diamond-shaped mazes can transfer the stretching forces, which are developed by the apparatus in the transport direction of the textile 28, very well to the textile, because the diamonds are stretched lengthwise and will become narrower in breadth.
Referring to Fig. 8, there is also shown an apparatus 35 provided with guiding surfaces disposed in a path to be followed in the apparatus. In this embodiment, these guiding surfaces consist of guiding bands 37 disposed on the outer side of the textile 36, and which, in the same manner as described for Fig. 7, keep the textile 36 on both sides in a plane, while the textile 36 is passed through the apparatus. This embodiment is particularly suitable to feed textile of relatively small dimensions, such as, for instance, table napkins, while properly held in a plane, through the apparatus. In Fig. 8, with the same reference numerals as in Fig. 7, the input 31, the guiding rollers 32 and the output 33 are represented, as well as return rollers 34.
With reference to Fig. 9, a variant of the embodiment of Fig. 8 is represented, in which the textile 36, for instance table napkins, is stretched by the corners 38 in a plane by means of dragbands 39 which are guided by guiding bands 40 disposed outside the outer sides of the textile 36, and which
keep the textile 36 in a plane, while the textile 36 is passed through the apparatus.
With reference to Fig. 10, an alternative embodiment of an apparatus 40 is represented, also particularly suitable for textile cloth of a relatively lesser dimension, such as table napkins 41. In the same manner as in Fig. 8, the napkins are stretched, with dragbands 42, by their corners 43 in a plane, however, in a manner such that the guiding bands 44, 45 can maintain the textile 41 in a direction transverse to the transport path. As is indicated with the interrupted arrow R, the napkins are moved at their upper side with brief accelerations, while the underside is moved at a uniform speed, represented with the uninterrupted arrow S. In this manner, the mutual distance between the corners 43, via the dragbands 42, is periodically increased and decreased, so that a controlled stretch can be applied on the napkins. The above-mentioned embodiments form illustrations of an apparatus in which the invention is used, in particular a washing apparatus. It is clear that the invention can also be used in other textile treatment processes customary in the textile refining industry, such as rinsing, impregnating et cetera of textile webs. Further, various other embodiments are conceivable, which also fall within the range of the following claims. For instance, combinations of guiding path arrangements are conceivable, wherein different designs of the guiding rollers of Figs. 3 - 6 are applied. It is also conceivable, in a variant of the embodiment represented in Fig. 10, that a stretching movement is applied to textile by feeding the textile, by its corners, along wave-shaped guiding rails.