Patent Application
20140047731
N/A
The present invention generally relates to an apparatus and method for controlling the conveyor speed of a textile dryer upon startup to conserve energy.
Indicia applied to articles of clothing and other textiles have become very popular. Fanciful indicia, such as slogans, logos, college names, sports team names and logos, and sayings are commonplace.
Indicia are printed using screen printing machines, with one or more colors. Typically, a screen printing machine has at least one station to print each color. Each station generally includes a printing head, which supports a single screen, the ink, and a mechanism for applying the ink to the textile or substrate. The textile to be printed travels between printing stations. The textile is typically carried by a metal pallet, pallet support, flat bed, or platen. Common printing machines are of the turret-type, or are oval or linear in configuration.
Some printing machines incorporate ink curing stations. Other operations employ separate dryers. A dryer has two primary components: a conveyor system and a heating system. Typically, the drying operation includes an operator setting the internal dryer temperature and the conveying speed to achieve the desired drying characteristics. Commonly known mechanisms are employed to determine or read the ambient temperature in the dryer, which allows the operator to adjust the conveyor speed to compensate to achieve the desired drying.
Numerous inks are available. Such inks include water based inks, sublimation inks, and plastisol. The ink is cured or gelled onto the substrate to a critical temperature. The temperature during the curing process must be kept within a suitable window depending on the ink's curing properties, typically between 125 and 450 degrees Fahrenheit. For example, plastisols must reach a temperature of 320 degrees Fahrenheit. In the ranges below 320 degrees and above 350 degrees, the plastisol will not properly set, resulting in cracking, or it may become liquified. Moreover, if a dye in the textile is overheated, it will migrate, or the textile or substrate may scorch or burn, increasing waste and production costs.
To solve this issue, dryers such as disclosed in U.S. Pat. No. 5,937,535 were developed to sense and control the drying process. Dryers are typically electric or gas-powered, use a great deal of energy, and are essentially a heat sink. The present invention provides an improved belt control system that reduces the amount of energy the dryer uses on startup, thereby reducing energy consumed in the drying process, and cutting costs of operation.
In one embodiment, a conveyor speed control system for a dryer is provided. The system includes a dryer having a housing with an entrance and an exit, and a conveyor within the housing, the conveyor capable of moving at a desired speed. A sensor senses the temperature of the interior of the dryer housing. A controller is provided. The controller receives a signal from the temperature sensor. The controller also controls the speed of the conveyor, and limits the speed of the conveyor to a desired speed until a desired dryer housing temperature is attained.
In another embodiment, a process for drying is provided. The process includes the steps of warming up a dryer at a first conveyor speed until a desired dryer temperature is attained, and operating the dryer at a second conveyor speed faster than the first conveyor speed.
In a further embodiment, a process for operating a dryer is provided. The dryer has a housing and a conveyor capable of moving at a desired speed within the housing. The process includes the step of warming up the dryer housing until a desired temperature is attained. The process also includes the steps of controlling the conveyor speed at a first conveyor speed before the desired temperature is attained, and controlling the conveyor speed at a second conveyor speed faster than the first conveyor speed after the desired temperature is attained.
To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which:
While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.
Referring to the Figures,
Heater elements (shown schematically at reference number 22) are within (generally below the conveyor 20) or immediately adjacent the dryer housing 11. An intake blower and an in-line blower are positioned within or adjacent the housing. Ducts (represented by duct openings 26) bring the air into the dryer housing 11 above the conveyor 20. There are generally two blowers employed. One blower draws fresh atmospheric air into the system to mix with the gas and burn, and the second blower moves the heated air into the heating area above the conveyor.
In the embodiment shown, there are four (4) “zones” shown. The first zone (preheating zone) is just after the inlet 16 and in the vicinity of the separate infrared preheater 18 (
A plurality of inclined deflectors 28 are located below the conveyor 20 for directing the air passing through the housing 11 and conveyor 20 to exhaust ducts (represented by duct openings 29). An exhaust blower is connected to the exhaust ducts 29 to transport the exhaust air to either a stack 30 for release into the surrounding atmosphere or back into the system 10 to recirculate the heated air and increase the assembly's efficiency.
While not shown, a circulation blower and blower filter screens are also employed. The system is also insulated to ensure safe use thereof.
In most systems, there is a means to detect the temperature inside the housing. Such means include industrial grade thermometers that measure the ambient air within the housing. This information is fed to the control panel 31 and displayed and assists an operator in deciding whether to manually adjust the conveyor's speed, the heat applied, and/or the air movement (cubic feet per minute—“CFM”).
Below is a chart of test results of natural gas usage and time to an operating temperature of 375 degrees Fahrenheit for a Sprint 60 dryer manufactured by M&R Printing Equipment, Inc., of Glen Ellyn, Ill., at a belt speed of three feet per minute versus twenty feet per minute.
As the chart above shows, the average natural gas usage for warming up the dryer from 150 to 375 degrees Fahrenheit at 20 feet per minute was 50.5 cubic feet. The average natural gas usage at 3 feet per minute was 38.75 cubic feet, a difference of 11.75 cubic feet. Moreover, the dryer heated up to 375 degrees approximately 2 minutes faster at a belt speed of 3 feet per minute versus 20 feet per minute. That equates to a 22% time reduction and a 23% gas consumption reduction.
While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying Claims.
The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/684,244, filed Aug. 17, 2012, the contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61684244 | Aug 2012 | US |
