The invention relates to carpeting tools, and more specifically to carpet seaming tape irons used for seaming carpet edges in the well known conventional manner, using hot melt carpet seaming tape.
Heat shields of polytetrafluorethylene material (Teflon, a trademark of DuPont), for fitting onto a carpet seaming tape iron, are well known. It is known that the Teflon material produces a low-friction glide against the carpet backing as the iron is advanced during the seaming operation. Also, Teflon is quite heat resistant and somewhat insulative as are many plastic materials, and with the Teflon heat shield lying over the existing stainless steel heat shield of the iron, the carpet is insulated from contact with the hot metal heat shield. This purpose of the known heat shields has been to prevent overheating of the carpet backing which can destroy the integrity of the carpet backing and/or the seam formed during the hot melt seaming operation. A typical add-on heat shield for fitting onto existing irons has been marketed by Roofing Equipment Inc., 11075 E. 47th Avenue, Denver, Colo.; and also by Orcon Corporation of Union City, Calif. This heat shield device had a pair of legs forming a slot between them, with the front ends of the legs riveted together. Such construction provided an opening which could be positioned over the handle of an existing iron, so that the heat shield could be assembled down over the handle. The legs at the front end enabled some pivoting at this point about the rivet, adding to the flexibility of the slot when installed over the iron's handle.
One problem with such conventional retrofittable heat shields has been that, even though the heat shield was formed in a nonplanar, somewhat contoured configuration, the heat shield did not fit down closely over the upper surface of the iron and tended to lie on the iron with edges riding considerably upward from the iron's metal heat shield. Another problem of such heat shields has been their length, generally co-extensive with the back end of the iron's upper surface and extending nearly to the front of the iron. Extension of the heat shield in front of and behind the handle was necessary due to the manner in which the heat shield was installed on the iron--by fitting a slot over the iron's handle. Material was required forward of the handle and rearward of the handle for adequate integrity of the structure--to receive a rivet on the one end, and to form an adequate juncture at the other end to hold the heat shield together.
Irons in other fields have also employed heat shields or protective insulative layers, usually to protect the user. In the field of flatirons, see U.S. Pat. Nos. 3,793,753, 2,579,726, 2,095,954, 626,286, 279,971, 191,935, 142,334, 75,611 and 58,138.
Thus, prior carpet iron heat shields of the type described exhibited several problems--effectively raising the profile of the carpet seaming tape iron and hindering the installer; sometimes underheating the carpet backing during the seaming operation; and generally giving the appearance and feel of not fitting properly over the top of the seaming iron. These and additional problems are overcome by the heat shield of the present invention described below.