Electric heating – Metal heating – By arc
Reexamination Certificate
2002-01-10
2004-04-27
Van, Quang T. (Department: 3742)
Electric heating
Metal heating
By arc
C219S121390, C219S121480
Reexamination Certificate
active
06727457
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus and method for draft control and easy debris removal in a downdraft cutting table. Downdraft tables are typically used by industry to cut shapes out of metal using manual or automated means to control the movement of a plasma or laser cutting head.
2. Description of the Related Art
It is common practice in industry to use a vacuum based downdraft table to remove smoke and collect the related debris caused by cutting metal with plasma or laser cutting equipment. In the metal cutting process, byproducts of smoke and airborne particulate matter are produced. The smoke and particulate matter creates an inhalation health concern for the workers who are operating the cutting equipment. Downdraft tables are typically used in an attempt to remove the smoke and airborne particulate matter from the air the workers breath. In addition, particulate matter and small scrap drop off parts are collected in the bottom of the downdraft table. Typically downdraft tables produce a vacuum under the metal being cut by use of fans to draw the smoke and debris down and away from the worker.
One problem with such tables results from the fact that the fan must draw the airborne smoke and debris from the entire area of the cutting table. The suction created by the fan is often not great enough to remove the airborne smoke. In order to concentrate the suction of the downdraft table the worker must place a covering such as another piece of metal or nonflammable tarpaulin over the area of the table not covered by the metal that is being cut.
In an effort to create as much suction as possible, most downdraft tables minimize the distance between the cutting area and the suction fan and provide the most direct air route available. A problem is created when an air filter is then used to clean and return the air to the workers' environment because airborne sparks arriving at the air filter elements will burn holes in the air filter element, gradually reducing the ability of the filter to properly clean the air, and creating the possibility of a fire. In addition, most downdraft tables have no easy way to remove the particulate debris and small scraps that accumulate in the bottom of the table. This results in the necessity of regularly taking the table out of commission for cleaning.
What is needed is a downdraft table that will allow for effective concentration of suction for smoke removal in the cutting area while depositing particulate debris and small scraps in an easily removable cleaning receptacles while reducing the possibility of passing sparks to an air cleaning filter.
SUMMARY OF THE INVENTION
The present invention comprises an apparatus for draft control and debris collection in a downdraft metal cutting table is disclosed. The apparatus includes one or more partitions positioned beneath the work surface of the table which divide the table into a plurality of suction zones, each of which communicate with a suction source. Each suction zone is equipped with a damper positioned to selectively control airflow through the respective suction zone between the suction source and the work surface. Each damper includes a damper flap having a proximate end pivotally connected to the table. Means are provided for selectively opening and closing the damper flaps. When the flaps are open, a distal end of each flap extends downwardly from the proximate end. Slidably. removable debris collection receptacles are positioned beneath the dampers such that when said dampers are open, debris falling through the work surface is directed into the receptacles by the damper flaps.
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