This invention relates to apparatus and methods for inserting an angle plate in channel shaped flanges of a duct.
A typical sheet metal duct section of the type used in heating, ventilating, and air-conditioning systems (HVAC systems) is usually square or rectangular in cross-sectional shape. Such a duct section usually has channel-shaped flanges extending outwardly from its end edges for end-to-end attachment to another duct section. Corner (or angle) plates having first and second legs are inserted into adjacent flanges in a manner so that the first leg is in one flange and the second leg is in the other flange. The flanges are then crimped to secure the angle plates in the flanges. Each angle plate has at least one aperture therethrough. When duct sections are positioned end-to-end, then the angle plate apertures of one duct section align with the angle plate apertures of the other duct section. The aligned apertures are configured for receiving threaded fasteners (e.g., bolts and nuts) to clamp the duct sections together.
Insertion of the angle plates into the flanges is typically performed manually. A technician places the angle plate on the flanges, forces the angle plates into the channel shaped flanges with a hammer or other suitable tool, and then manually crimps the flanges. The primary problems associated with such manual insertion is that this operation is labor intensive and time consuming.
Machines have been used to automatically remove an angle plate from a stack of angle plates and insert it into duct flanges. A problem associated with such machines is that only special types of angle plates can be used with such machines. Conventional angle plates come in a wide variety of shapes and configurations, and most of these angle plates are configured to nest with identical angle plates. The only angle plates which can be used with the prior machines must be shaped so that they do not nest with other angle plates in the stack of angle plates. If the angle plates nest in the stack, the machines are incapable of removing the plates from the stack. Thus, most types of angle plates cannot be used with the machines.
Another problem associated with such machines is that different drive mechanisms are needed to perform the various operations of the machines. For example, a machine might need one drive mechanism for positioning the duct on the machine, another drive mechanism for aligning the angle plate with the flanges, another drive mechanism for pressing the angle plate into the flanges, and another drive mechanism for crimping the flanges. These multiple drive mechanisms complicate the operation of a machine and increase the likelihood of machine failure.