WO2012035179A1 - Automatic tunnel for drying screen-printed products - Google Patents

Abstract

The invention relates to a tunnel comprising a conveyor belt (2) on which the items of clothing (4) with the screen-printed design to be dried are placed. The conveyor belt (2) has an inlet area (3), a drying area (5) and an outlet area (6), such that a matrix of infrared emitters (8) used as heating elements is provided in the drying area (5), mounted on a platform (7) that can be actuated manually or by means of a motor, for moving said platform in an upwards and downwards direction, and therefore moving it away from, or towards, the screen-printed design provided on the item of clothing (4) arranged in the drying area (5) of the conveyor belt (2).

Description

 AUTOMATIC PRODUCT DRYING TUNNEL

 SERIGRAFIED

D E S C R I P C I Ó N

OBJECT OF THE INVENTION

The present invention relates to an automatic drying tunnel for screen-printed products, specifically intended for drying in screen printing or textile processes, without ruling out other possible applications with other types of materials.

The object of the invention is to achieve a significant reduction in the volume of the drying tunnel, based on a discontinuous operation, which in combination with the use of infrared emitters as drying elements, will lead to a considerable reduction of the electrical consumption and of the manufacturing costs of the drying tunnel itself.

BACKGROUND OF THE INVENTION

In conventional serigraphic drying tunnels, the product, (pledged with screen printing), is carried by a conveyor belt through the tunnel itself through different areas, during which the heating of the tunnel takes place.

The main elements that a conventional drying tunnel has are the following: - A conveyor belt that is responsible for collecting and transporting the different products to drive them along the tunnel, the drive system of the set being an electric motor that is responsible for moving a belt continuously and slowly, being that fiber belt normally of glass.

- A series of fans by means of which air jets are projected that facilitate the extraction of evaporated water or humidity, having a second very important function that is to create a homogeneous temperature inside the drying chamber based on removing the air in its interior

- An extractor system responsible for renewing the air inside the drying tunnel, thus removing the vapors released in the drying process and sending them through a duct to a safe evacuation zone.

- Some heating elements by means of which sufficient heat is generated to reach the printing drying temperature, the elements used can be of various types, according to their nature, citing as conventional examples the conventional heating emitters, the infrared emitters, gas boilers, etc.

Well, conventional drying tunnels of the aforementioned type are preferably and fundamentally intended for application in large companies, while in medium and small companies the type of referred serigraphic drying tunnel presents a series of drawbacks that can be summarized in the following :

1. For large volumes the drying tunnel needs a large volume to be able to perform the drying correctly. 2. The conventional tunnel type carries excessive consumption that in most cases makes the power supply unfeasible.

3. Regarding the homogeneity / veracity in temperature, problems are frequent in which due to the heterogeneity of the temperature of the drying zone, the indicated temperature is not the actual temperature, all due to causes design or wear or failure of the components.

4. Due to the technical and material complexity used, the initial economic cost is very high.

If, on the contrary, it is decided to dispense with the referred system and use other more basic alternatives, such as air-drying carts, hand dryers, small infrared dryers, etc., then the problems are the following:

1. Low productivity and long time delays, because drying is slow and the units treated will be minimal.

 2. Low or no automation, so the operator must perform the drying or most of the process.

DESCRIPTION OF THE INVENTION

The automatic screen printing drying tunnel that has been recommended has been designed to solve the above-mentioned problem, being precisely provided to provide a useful solution halfway between drying systems for large volumes of productivity and methods more basic and very low productivity.

More specifically, the automatic screen-drying tunnel of the invention, being constituted from a conveyor belt on which the products are arranged, includes a platform with an array of infrared emitters, so that the area of said matrix will be designed with the objective of completely covering the screen printing on the products or batches of products for which the drying tunnel is intended. The platform that supports the matrix of infrared emitters will be arranged forming a plane parallel to the conveyor belt, and a vertical separation that will be given by the maximum height of the products that can pass under it, so that the placement of the emitter platform infrared will be carried out in such a way that three contiguous zones can be distinguished on the belt, one of entrance, with a minimum surface area equal to or greater than the drying zone; a drying zone proper that corresponds to the area occupied by the matrix of infrared emitters, and an exit zone that is not subject to any specification as to its surface.

On the other hand, the drying tunnel will have sensors to know the surface temperature of the products that are under the infrared emitters and to recognize when the product is located under them, complementing with a control unit for running control. stopping the belt, all with the objective of collecting the products one by one from the entrance area and placing them in the drying area for a certain time, after which they will be removed to the exit area.

The tunnel will also have the necessary means for the operator to set the temperature on the surface of the garment and the residence time of this over the drying zone.

As for the conveyor belt, it will have a fixed and reduced speed, around 0.2 m / s and in only one direction, and in which there will be the three areas mentioned, that is, entrance area, drying zone and exit zone, based on the operation of the conveyor belt in the idle march of the same, getting garments in the entrance area to the tunnel, leaving them in the drying area for the time indicated by the operator, and removing them when it ends , so that the drying zone will give way to the garment collection area, where the process will be terminated and the operator can withdraw the products.

For its part, the matrix of infrared emitters will be mounted on a mobile platform, allowing the distance between screenprinted garments and infrared emitters to be adjusted, based on a lifting mechanism that can be manipulated manually or automatically, a mechanism that must have a sensor element that allows to know the distance between transmitter and garment. The garments will pass through the tunnel with a minimum separation between them, so that the sensor systems will be responsible for determining when the garment is at the entrance of the tunnel, when it is over the drying area, or when it leaves the tunnel, allowing to control the logic, activate the conveyor belt, being able to use among other laser barriers placed at the entrance immediately after the drying zone, all this so that the basic process step by step would be as follows:

- Garment entry area, where the corresponding garment is detected and its subsequent placement in the drying zone. - Drying phase of the garment, placing it under the infrared emitters constituting the heating elements themselves, making a time delay with the conveyor belt stopped, to give rise to drying.

 - Exit phase of the garments, where each garment is removed from the drying zone, moving it towards the corresponding exit zone.

As for the infrared emitters, they will logically be medium-wave infrared resistors (0.5 to 3.3 microns) and will have temperature sensors attached to their core, said emitters being connected to an individual reflective metal screen that will direct the infrared rays of the emitter, so that from now on each infrared emitter is considered as the set of the emitter itself and the reflecting screen.

Depending on the morphology of the infrared emitter and the reflecting screen, the infrared rays will be directed in a certain way, then having an optimal distance in which the emitted heat power is concentrated, so that the nominal electrical power of the infrared emitters It will be given by the maximum desired temperature on the product to dry when working at the optimum distance. As for the degree of drying, it will depend on the exposure time of the garment to the infrared exposure and the temperature reached on the surface of the garment, being the configuration of the infrared emitters on the matrix type tape on the mobile platform, grouping by sets the infrared emitters, so that they can be activated independently.

In the drying tunnel, it will also have at least one extractor that will be in charge of renewing the air inside the drying chamber and redirecting the vapors that have emerged to a safe area through an evacuation pipe. outside, being able to complement with fans to strengthen the smoke extraction effect of the garment.

There will also be a distance sensor between the infrared emitters that will go on a mobile support that can move vertically with respect to the conveyor belt, allowing the user to zoom in or out of the infrared emitters with respect to the garment, being able to directly influence the energy received on it . Depending on the morphology of the infrared emitters there will be an optimal distance in which the consumption is reduced to the smallest possible, so that the vertical displacement of said infrared emitters could be automated by means of an elevator motor, although another option would be to carry out lifting / lowering manually by the user. For the determination of the emitter-tape distance there will be a distance sensor that allows the measurement in a range between 1 cm and 30 cm, being able to use for example an appropriate optical distance sensor.

The drying tunnel will also include a lifting system for the infrared emitters, specifically the support of said emitters, so that it is allowed through the use of an electric motor or a steering wheel, automatic and / or manual lifting / lowering of the emitters support on the drying zone.

The drying tunnel is also equipped with a hot air conduction system generated inside the tunnel which, by extraction and after filtering, will send the hot air to the tunnel entrance.

The temperature on the surface of the screen-printed garment can be adjusted, so that depending on the mathematical expression that relates The distance between the infrared emitter and the garment, the internal temperature of the emitter itself and the ambient temperature around the product, will establish the modification of the electric operating power of the emitter and the distance of the emitter-garment, until the desired surface temperature is achieved. .

Lastly, it is established that a method of locating drying of screen-printed products is established, which receives a heat emission from a set of infrared emitters, with which it will be possible to activate each of them independently, so that it is only under infrared radiation the area where the screen printed on the garment is placed.

To the combination of the elements referred to above, it should be noted that it will be complemented with an electronic control system that provides solutions to the problems raised, which are the following:

- Large volumes: The change with respect to conventional tunnels is that the belt will perform a discontinuous march, stopping the garment under the drying area for the time necessary to perform this task, thereby trying to reduce the length of conveyor belt, sacrificing for this, productivity since the clothes will dry one by one.

- Large consumption: The main reduction in consumption will result from the reduction of the drying zone and the use of infrared emitters. It will no longer be an attempt to raise the temperature of the entire interior environment, but rather to focus the heat on the garment. In addition to this, systems for reducing consumption such as selective activation of infrared emitters will be implemented, whereby the user decides on the drying zone to be activated, since the Issuers will be grouped by sets.

Homogeneity / veracity in temperature: Due to the operating nature of the infrared emitters, the actual temperature that exists on the surface of the garment can be measured by remote temperature sensors, indicating the temperature on the garment regardless of the operation of the garments. emitters In addition, the individual temperature of each resistor (infrared emitter) will be available, so you can always know if any emitter is damaged or failing.

 Low productivity: the productivity of the drying tunnel will be defined by the time that the garments must be in the drying zone, it being not possible to define a fixed time because it will vary depending on the nature of the materials and the colors of the garments, but the drying margin will not exceed the order of the minute, so it will more than cover the cadence of a production company. In addition, the tunnel will have a garment collection area that can be arranged so that there are several garments at the tail of the drying zone.

Low automation: To operate the drying tunnel, only one operator will be required to deposit the garments at the beginning of the conveyor belt.

High initial cost: the reduction of the economic cost is considerable due to the reduction of necessary material. In addition, the drying zone does not have to be thermally insulated, so the material used will meet minimum characteristics and the associated cost will be reduced. DESCRIPTION OF THE DRAWINGS

To complement the description that will then be made and in order to help a better understanding of the features of the invention, according to a preferred example of practical implementation thereof, a set of drawings is attached as an integral part of said description. where, for illustrative and non-limiting purposes, the following has been represented:

Figure 1 shows a representation corresponding to a general perspective of the discontinuous drying tunnel made in accordance with the object of the invention.

Figure 2 shows a bottom perspective view of the platform that supports the array of infrared emitters that is part of the object of the invention.

Figure 3.- Shows a top perspective view of the lifting system of the infrared emitter system.

Figure 4.- Shows a perspective and unitary view of an infrared emitter.

Figure 5.- It shows, finally, a cross-sectional elevation, indicative of the infrared-garment emitter height, located on the corresponding conveyor belt.

PREFERRED EMBODIMENT OF THE INVENTION As can be seen in the aforementioned figures, the discontinuous drying tunnel object of the invention is constituted from a bed or general structure (1) in which a conveyor belt (2) that runs in a horizontal plane is mounted, in which establishes three well differentiated zones, a first zone referenced with the number (3), which corresponds to the entry, on which the corresponding garments (4) equipped with the screen printing to be dried are arranged.

Next to said inlet zone (3) a drying zone (5) is included, and then an outlet zone (6), with the particularity that in correspondence with the drying zone (5) a platform (7) as a support for a plurality (matrix) of infrared emitters (8), being elevable in height by means of a threaded shaft or worm (9), or similar element, mounted on a bridge (10) and driven , either by means of a hand-operated steering wheel (11) or by means of a motor established on the upper end of the screw (9).

In any case, the infrared emitters (8) are constituted in each case by an infrared resistor (12) and a reflecting screen (13), each infrared emitter (8) being seen individually in Figure 4, since all of them they form a matrix linked to the support platform (7) already commented and represented in figure 2.

The matrix or set of infrared emitters (8) with the support platform (7) are mounted on a frame (14) provided on the bed or general structure (1), as shown in Figure 1, so that a fan (15) extracts the hot air generated by the infrared emitters located on the heating zone (5) of the conveyor belt (2), so that through a filter it extracts the hot air towards the tunnel entrance area, that is to say of the conveyor belt (2), through an appropriate screen (16), as can also be seen clearly in Figure 1.

Both the structure of the frame (14) of the drying zone (5), as well as the platform itself (7), will be made of alurninium profiles with enclosures in plastic materials, for example methacrylate, so that the enclosures will be ready to be easily removable and facilitate maintenance. The dimensions of the drying zone (5) will be consistent with the maximum surface of the products or garments (4) to be dried, also taking into account the margins to add any essential element for operation, such as electronic boards, guides, barriers, sensors, etc. Preferably the drying zone (5) will be arranged at the end of the conveyor belt (2), as shown in Figure 1.

As for said conveyor belt (2), it will have a support structure based on aluminum parts and will contain a motor roller, either as an external element of a motor-drum assembly, and another counter motor, both provided at the ends of the same and referenced with the numbers (17 and 18), respectively, disposing in intermediate points with crazy rollers (19) as support elements for the conveyor belt in its course and therefore for the silk-screened garments (4). The support for the countermotor roller (18) must allow a horizontal adjustment movement for the tensioning of the conveyor belt (2), which must be materialized in a material that supports the temperature achievable in the worst situation, which will depend on the power of the heating elements or infrared emitters (8) and the distance of the conveyor belt (2) to them, the option of use Teflon tape or fiberglass, so that the dimensions of it will depend directly on the dimensions of the drying zone (5), also leaving a length greater for the garment collection area, as large as garments are They want to have in line.

For its part, the platform (7) support of infrared emitters (8), will be made by assemblies of aluminum profiles, as already mentioned above, provided that they allow all infrared emitters (8) to be arranged in matrix format, The electrical connections are made at the top of the platform (7), ensuring that there is electrical and thermal insulation between the wiring and the infrared emitters (8).

For its part, the lifting system of the infrared emitter matrix (8), has already been said to be based on an endless or threaded shaft, against a nut integral with the platform itself (7), in order to prevent the rotation of the latter and allow the upward and downward vertical displacement of the array of infrared emitters (8), so that to achieve the rotation of the threaded or endless shaft (9), a motor or hand-operated steering wheel will be available (11), as also stated previously.

As for infrared emitters, they will be ceramic, tile-shaped, as shown in the figures, and will house a thermocouple type temperature sensor inside.

Finally, the drying tunnel described will be complemented with the appropriate sensors that will be equipped with mechanisms for protection against the infrared spectrum, being able to use laser barriers and as a distance sensor an ultrasonic sensor.

Claims

 R E I V I N D I C A C I O N E S I ^a .- Automatic drying tunnel for screen-printed products, which being of the type that are constituted from a conveyor belt (2) on which garments (4) are provided with a screen printed that is intended to dry, is characterized because said conveyor belt (2) has a discontinuous movement and has an entrance area (3) in which the garments (4) are deposited with the screen printing; a drying zone (5), and an outlet zone (6), it being provided that in correspondence with the drying zone (5) there is an array of infrared emitters (8) mounted upwardly and downwardly movable to approximate or away from the garment (4) located in said drying zone (5), the matrix of infrared emitters (8) being mounted on a support platform (7) · 2 .- automatic tunnel drying screenprinted products according to claim 1, wherein the conveyor belt (2) runs between a motor (17) roller and a contramotor roller (18) at opposite ends thereof, complemented intermediate rollers (19) supporting the conveyor belt (2) and the silk-screened garments (4) deposited on it. 3 .- automatic tunnel drying screenprinted products, according to previous claims, characterized in that it includes a fan (15) corresponding to the drying zone (5) for the extraction of hot air and conduction to the inlet area the conveyor belt (2), through a filtering and ejection system (16). 4 .- automatic drying tunnel screenprinted products according to claim 1, wherein the matrix of infrared emitters (8) it has a plurality of said infrared emitters, capable of becoming independent from each other and operating independently of each of them, being constituted individually by an infrared resistor (12) and a metallic and reflective screen (13) for redirecting the infrared rays of the emitter correspondent. 5 .- automatic drying tunnel screenprinted products according to claim 1, wherein the matrix of infrared emitters (8) is linked to a carrier as a bridge (10) on which is threaded a threaded screw or worm ( 9) operable either by means of a motor or by means of a hand-operated steering wheel (11) for raising and lowering said matrix of infrared emitters (8), allowing its distance or approximation with respect to the garment (4) with the intended screen printing dry off. 6 .- automatic tunnel drying screenprinted, according to any of the preceding claims, characterized in that it comprises a number of detection sensors garments (4), in the entrance area (3), as in the drying (5) and in the exit zone (6); having provided a distance sensor for the matrix of infrared sensors (8), allowing the upward or downward displacement of these with respect to the conveyor belt and therefore with respect to the garment (4) with the screen printed to dry, also having sensors of temperature and a control unit through which the run / stop of the conveyor belt itself will be governed. 7 .- Automatic Tunnel drying screenprinted products, according to claim 6, characterized in that it includes means for adjusting the temperature on the surface of the silkscreen garment (4), depending on the mathematical function relating the distance between the corresponding transmitter infrared (12) and the garment (4), as well as the internal temperature of said infrared emitter (12) and the ambient temperature around the garment (4), in order to modify the operating electric power of the infrared emitter itself ( 12) and the distance between it and the garment (4), until the desired surface temperature is achieved. 8 .- automatic tunnel drying screenprinted products, according to claim 6, characterized in that the infrared emitters (8) are capable of independently activated each allowing the infrared radiation emitted is applied only on the area where is situated the screen printing of the garment (4).