Apparatus and method for treating fabric

Abstract

The apparatus (100) comprises several stations for treating fabric (10). For example, a cleaning station (20) is provided that is arranged to remove loose debris from the fabric and move the fabric in a continuous motion through the cleaning station. A treatment station (40) is then arranged to receive the fabric from the cleaning station and to transfer treatment fluid to the fabric in a treatment zone. Finally, a drying station (50) is arranged to receive the fabric from the treatment station and to dry the fabric in a drying zone. Advantageously, the treatment station is arranged to transfer the treatment fluid by spraying the treatment fluid under pressure onto a side of the fabric.

Claims

1. An apparatus for drying fabric, comprising a drying station comprising an emitter supported by a moveable arm, the emitter arranged to emit infrared radiation toward the fabric, the extent of which defining a drying zone, wherein the emitter is moveable in a predetermined way such that the drying zone is configured to span a width of fabric and successively dry the width of fabric; the apparatus further comprising a plurality of rollers for handling the fabric including at least one dancing roller configured to move relative to at least one other roller of the plurality of rollers; wherein the moveable arm is configured to move the emitter relative to the fabric when the fabric is held in position.

2. The apparatus according to claim 1, wherein the emitter is moveable along a predetermined path.

3. The apparatus according to claim 2, wherein the moveable arm is configured to move the emitter beyond the edges of the fabric.

4. The apparatus according to claim 3, wherein the drying station includes an extension along which the emitter is is adapted to move, and further wherein the extension and the predetermined path are collinear.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:

(2) FIG. 1 shows a known apparatus of pre-treating fabric prior to printing;

(3) FIG. 2 shows a representation of lint or dust trapped between the ink and fabric layers;

(4) FIG. 3 shows a side view of an apparatus for treating and printing on fabric;

(5) FIGS. 4, 5 and 6 show top, front and back views of the apparatus of FIG. 3, respectively;

(6) FIG. 7 shows a flow diagram of the treatment and printing processes; and

(7) FIG. 8 shows a cleaning station;

(8) FIGS. 9a to 9c show the operation of a dancing roller;

(9) FIG. 10 shows a treatment spraying station; and

(10) FIGS. 11a and 11b show a heating station and the movability of the heating unit.

DESCRIPTION OF EMBODIMENTS

(11) FIG. 3 shows a side view of a fabric treatment apparatus (100). Fabric (10) is fed (preferably as a roll) into a cleaning station (20) provided at the input end (A) of the apparatus (100). The cleaning station (20), as shown more clearly in FIG. 8, comprises air suction units incorporating a high pressure water supply and an adhesive coated roller (24) that removes lint or loose debris such as dust from the fabric. Air suction units (22) operate by vacuum effect to clean the adhesive roller and detach the loose material temporarily adhered to the roller (24) as the roller (24) rotatably contacts the fabric (10). The air suction units (22) remove the loose debris from the roller (24) so that the roller (24) can continue to effectively adhere debris from the fabric (10). The suction units (22) move along the roller (24) in a traverse direction to the direction of fabric (10) movement as shown in FIG. 5. The air suction units (22) therefore move in an axial direction parallel to the longitudinal axis of the roller (24) and effectively sweep the rollers (24) as they go. Preferably, the movement of the fabric (10) through the cleaning station (20) is substantially constant or is at least continuous so that no breaks in fabric (10) movement occur. This allows the fabric (10) to be continually fed through the system (100) without interruption. However, in alternative embodiments, the roller is cleaned off-line.

(12) Once the fabric (10) has been cleaned, the fabric (10) is fed towards a dancing roller (30), the function of which is more clearly shown in FIGS. 9a to 9c. The dancing roller (30) converts the continuous motion of the fabric (10) exiting the cleaning station (20) into intermittent motion for supply to the rest of the apparatus (100). This allows the treatment process to be integrated as one with a printing process comprising an inkjet printer. The dancing roller (also known as an accumulator) is a term of the art and its general operation and effect is known. However, the operation in this current disclosure is briefly described in FIGS. 9a to 9c.

(13) FIGS. 9a to 9c show the dancing roller (30) in operation. Fabric (10) is divided into four lengths (10a,10b,10c,10d). Each length represents a time block of unity and is therefore equal in length when a constant feeding speed is used. The dancing roller (30) has a displaceable axis so that the dancing roller (30) axis moves with respect to the axes of the cleaning rollers. As the fabric (10) is fed towards the dancing roller (30), the dancing roller (30) moves away from adjacent rollers in a downward direction (C1) as shown in FIG. 9b. The downward motion is simultaneous with the feeding motion and preferably operates at the same velocity. This allows one end of the first length of fabric (10a) to remain effectively stationary. As shown in FIG. 9c, the dancing roller (30) continues to move downwards as more fabric (10) is fed from the adjacent roller. This ensures that the fabric (10) does not slacken. Once three time periods have elapsed, the dancing roller (30) returns to the initial position in an upward direction (C2) as shown in FIG. 9d. This allows the three lengths of fabric (10a,10b,10c) to be fed towards the next station. Advantageously, the dancing roller (30) converts continuous motion to intermittent motion so that an inkjet printer can be integrated with a pre-treatment station (20).

(14) Referring back to FIG. 3, once the fabric (10) leaves the dancing roller (30) the fabric (10) is sent to the treatment station (40). The treatment station (40), as shown more clearly in FIG. 10, comprises a moveable treatment zone (i.e. a spraying zone) is delineated by the extent of fluid spraying by the nozzles (42) on to the fabric (10). The spraying zone moves by an arm (46) in a transverse direction (D) across the width of the fabric (10), as shown in FIG. 4. Here, the nozzles (42) spray fluid, i.e. pre-treatment chemicals onto one side of the fabric (10) only (i.e. the top side), while moving back and forth in a direction orthogonal to the direction of fabric (10) movement through the apparatus (100). A mechanical atomisation nozzle may be used which avoids the use of air. This allows smaller droplets to be sprayed towards the fabric (10) so that a consistent distribution of treatment fluid is transferred onto the fabric (10). During the fluid spraying stage, the fabric is held substantially constant due to the movement of the dancing roller (30) even though the fabric (10) is continuously fed through the cleaning station (20).

(15) The spraying zone is arranged such that the fabric (10) in contact with rollers (48) is not sprayed onto because contact with the rollers (48) can affect the integrity of the fabric (10) causing localised deformation compared to regions not in contact with the rollers (48). Therefore, only the unsupported fabric (10) is sprayed. That is, the spraying zone is arranged to act on an area between two supporting rollers. The duration, flow rate, pressure, volume, and average droplet size distance of the spray can be controlled in order to intimately affect the transfer or pre-treatment chemical to the fabric (10). For example, a pressure of between 50-100 bar can be used with or without a mechanical atomisation nozzle. A high velocity spray may be used. The spray may be provided as a fine mist of vapour. Therefore, the penetration distance into the fabric (10) from one side of the fabric (10) can be varied. For example, a penetration level between 50-75% can be easily achieved. To prevent the spread of any excess fluid, a barrier (44) is placed below the fabric (10). In addition to the pre-treatment process a post-treatment process may be used. The post-treatment process may transfer chemicals onto the fabric (10) in order to make the fabric (10) water repellent.

(16) Advantageously, the treatment station (40) has the ability to control the penetration level of the treatment fluid by, for example, varying the speed of movement, the pressure, volume, flow rate of fluid ejection and the number of nozzles. This means that there is no need for a mangle to draw excess fluid out of the fabric (10), which helps to make the apparatus (100) more compact and efficient. There is also no need to submerge the fabric (10) in a fluid bath, which improves the quality control of the fluid and avoids the need to store treatment fluid in a reservoir. Furthermore, rollers are not directly exposed to the treatment chemicals during spraying.

(17) Once the fabric (10) has been treated, the fabric (10) is intermittently fed to a drying station (50) as shown in FIG. 3. The drying station includes means for applying heat energy. In some examples, using an emitter supported by a drying support. Suitably, the emitter comprises a heating element. Conveniently, the emitter comprises a reflective backing.

(18) In some examples, the emitter is chosen and tuned to emit radiation of certain range of wavelengths. Conveniently, the range is suitably chosen for the fabric and coating to be dried. In some examples, the emitter is arranged to emit predominantly a narrow range of wavelengths. In one example, the emitter is arranged to emit close to a single wavelength.

(19) For example, for drying fabric, and preferably cotton, a wavelength of more than 1.3 m (micrometres) is chosen. Preferably, a wavelength of 1.38 m is selected. Conveniently, for drying cotton a colour temperature in a range of 2000-2200 K (Kelvin) is chosen. In some examples, the colour temperature is 2100 K.

(20) In some examples, the emitter comprises a highly reflective backplate to increase the efficiency of the transfer of energy to the fabric. Additionally or alternatively, a highly reflective plate may be placed opposite to the emitter in a direction of emission such that, in use, fabric is located between the emitter and the highly reflective plate. Conveniently, the highly reflective plate is arranged to reflect emitted energy. Suitably, emitted energy which has passed the fabric may thereby be redirected towards the fabric.

(21) In some examples, the drying station comprises means for transferring mass from the fabric during the drying process. Conveniently, the drying station is configured to remove fluid, preferably moisture, resulting from the drying process.

(22) Conveniently, the amount of heat energy emitted by a drying head of the drying station is chosen for quickly drying the fabric and removing any resulting vapour. In some examples, such may be achieved within a few seconds per square meter and, in one example, one second per square meter.

(23) In this example, the drying station, which is more clearly shown in FIGS. 11a and 11b, comprises a moveable infrared drier (52). When in the drying position, a length of fabric (10) placed between the infrared drier (52) and a heat shield (54), such as a reflector, is heated by the thermal energy transferred by the infrared radiation. The region of thermal energy emitted from the infrared drier (52) is the drying zone. The proximity of the infrared drier (52) to the fabric can be varied in order to affect the speed of drying and/or heating. For example, a distance of between 100-200 mm can be used when the infrared drier (52) is static or a closer distance of between 25-100 mm, or preferably 10-50 mm, can be used when there is relative movement between the infrared drier (52) are the fabric (i.e. the infrared driver (52) is continuously moving). This allows the infrared drier to be close to the surface of the fabric (10) to be dried and/or heated. Advantageously, the use of an infrared drier (52) allows the drying means to be turned on and off as required because the infrared drier (52) can warm up quickly without detrimental performance effects. Furthermore, the drying zone can be well controlled. For example, the speed of the drier (52) relative to the fabric (10) can be varied as well as the distance between the drier (52) and the fabric (10).

(24) A moveable arm (56) connected to the infrared drier (52) is configured to move relative to the fabric (10) when the fabric (10) is held in position. For example, the infrared drier (52) may move towards or away from the fabric (10) in a first direction (E1) and side-to-side in a second direction (E2), substantially orthogonal to the first direction (E1). The infrared drier (52) may move beyond the edges of the fabric (10). This helps to evenly spread the distribution of heat and avoid scorching of the fabric (10). The sideways movement of the infrared heater (52), i.e. in the second direction, is preferably timed according to the movement of the dancing roller (30) and the spraying of the fabric (10). Therefore the fabric can be held in position in a stop-start nature to allow sections of the fabric (10) to be acted on at once. Alternatively, or additionally, the drier (52) may rotate away from the fabric (10) such that the drying rate of the fabric (10) is reduced even if the drier (52) remains on. Additionally, air movement over the fabric (10) may be used by blowing or suction force in order to encourage the removal of fluid particles from the fabric (10). Additionally, or alternatively, the infrared drier (52) may move in an up and down direction, i.e. a third direction, which is substantially orthogonal to the first and second directions. This adds further configurability depending on the type of drying required.

(25) After the drying station (50), the fabric is sent through a printing station, which may be a separate station. When an inkjet printer is used (not shown), the printing nozzles acting on the fabric (10) move across the fabric (10) in a side-to-side motion. During the sideways movement of the nozzles, the fabric (10) is held substantially stationary in order to allow the ink to be passed onto the fabric (10) in a linear fashion. An array of nozzles arranged in a column (i.e. along the fabric (10)) may be used in order to concurrently move across the fabric (10) and act on a larger surface area. This allows a row of the fabric (10) to be printed on at once (as determined by the dancing roller (30)) before being moved out of the way by the next row of unprinted fabric (10). Advantageously, the continuous motion of the cleaning station (20) does not disrupt the stop-start motion required by the printing station (60).

(26) FIGS. 5 and 6 show the front and back views of the apparatus, respectively. Typically, the rollers (12) are elongate to reduce inertial load and accommodate fabric (10) that may be at least 3 m in width. The rollers (12) each has a rotation axis which may be powered or unpowered. Therefore, some rollers (12) may be used to drive the fabric (10) forward or may freewheel such that they spin freely. The axes of the rollers (12) are shown attached to framework (14) that provides the structure of the apparatus (100).

(27) FIG. 7 show a flow diagram of the apparatus (100) as a whole. The apparatus (100) is configured to receive a roll of fabric (10) and input the fabric (10) as a continuous length. After the input stage (200), the fabric is continuously fed to a cleaning stage (210), where debris is removed from the fabric (10) from at least one side of the fabric (10). The continuous motion of the fabric (10) movement is then changed into intermittent motion. Therefore sections of the fabric (10) are then fed to a spraying stage (220), whereby the fabric (10) is coated from at least one side with a pre-treatment fluid. The amount of penetration is controlled in order to embed the fabric (10) accordingly. After the spraying stage (220), sections of the fabric (10) are intermittently fed to a drying station (230), where the fabric (10) is dried in and the pre-treatment fluid is retained by the fabric (10). This drying action may extend to a heating action in order to prepare the fabric (10) for printing by inkjet. Once exposed to a drier in the drying stage (230), the fabric (10) is fed to a printing stage (240), whereby the fabric (10) is printed on by ink. This allows graphics to be applied to the pre-treated and dried fabric (10) before being outputted (250) for delivery or storage.

(28) Advantageously, the apparatus minimises changeover disruption so that a different pre-treatment chemical can be quickly and more conveniently changed. The extent of chemical penetration into the fabric can be controlled by the use of nozzles. The to provide a more flexible method of embedding the fabric. The moveable drier and/or improved transient nature of the drier prevents the fabric being scorched and allows the drying process to be unaffected when stationary. The moveable drying and/or spraying zone allows the fabric to be held in position. In summary, the apparatus provides greater customisation and flexibility for improved efficiency and reduced downtime.

(29) Although preferred embodiment(s) of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made without departing from the scope of the invention as defined in the claims.