GB2318544A

GB2318544A - A carpet seaming iron with improved heatshield and base plate, and a temperature controller for electrical appliances.

Info

Publication number: GB2318544A
Application number: GB9719916A
Authority: GB
Inventors: John Deveney
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-09-19
Filing date: 1997-09-18
Publication date: 1998-04-29
Also published as: GB9719916D0; GB9619579D0

Abstract

A carpet seaming iron comprises a base plate 52 heated by an electrical element 51 an upper surface and a handle. The upper surface forms a heatshield 20 with a plurality of ridges 21 which, in use, allow air to flow between the upper surface of the iron and the underside of the carpet 10, 11, preventing overheating and possible damage to the carpet backing. The ridges are preferably semicircular and the heatshield may be demountable. The electrical element may be formed of a wafer thin element formed by spraying a layer of metal oxide onto a stainless steel sole plate or it may be formed by applying a thick film resistive track such as a printed circuit onto a steel substrate. The base plate may be shaped to improve distribution of hot, melt adhesive by forming a raked leading edge (31, Fig. 5b) and a transverse rebate (32, Fig. 5b) along the lower leading edge. Additionally, an enlarged longitudinal inverted V shaped groove (60, Fig. 11) extending substantially across the whole width of the base plate may be formed at the rear thereof, possibly including a longitudinal channel (61, Fig. 10) adjacent each side of the groove. Finally, a preferred form of temperature control for any heated electrical appliance is disclosed whereby the control circuit (Fig. 13, 14), including a user adjustable temperature regulator (120, Fig. 13), is situated within the appliance plug (112, Fig. 15) only the temperature sensor (110, Fig. 13) being located within the appliance.

Description

SEAMING IRON The present invention relates to a seaming iron, particularly a seaming iron for use with hot melt adhesive tapes in joining two pieces of carpet. It also relates to a mains electricity plug for controlling the temperature of such an iron or other appliances.

With reference to Figure 1, conventionally, two strips of carpet 10,11 are joined together over a floor surface 15 using hot melt adhesive tape 12. The tape is laid under the join in the carpets and activated with an iron 13. An example of such a seaming iron is shown in GB 2,161,113 and Figure 1.

The known seaming irons have/a number of problems, of which tunnelling and peaking are two. Tunnelling occurs when the edges of the carpets to be joined form a bridge or arc 14 over the hot melt adhesive tape, with the result that the seam is raised visibly. This is illustrated in Figure 2. There are several causes which combine to cause tunnelling: i overheating the edge of the carpet whilst heating to melt the adhesive; ii premature cooling of the hot melt adhesive and the distribution of the adhesive across the joint, and iii the amount that the edges of the carpet have to be raised to allow the seaming iron to pass under the edges.

The present invention is concerned with a number of improvements which seek to address these problems.

In a first aspect, the present invention provides a carpet seaming iron having a base plate heated by an electrical element, an upper surface and a handle, wherein the upper surface forms a heatshield and is provided with a plurality of longitudinal ridges.

In a second aspect, the present invention provides a carpet seaming iron having a base plate heated by an electrical element and a handle wherein the base plate has a leading edge raked at an angle of from 80 to 250 and includes a transverse rebate at the lower leading edge of the base plate.

In a third aspect, the present invention provides a carpet seaming iron having a base plate heated by an electrical element, wherein the heating element is a thin film of metal oxide of between 20 and 150 microns thickness upon a stainless steel sole plate or wherein the base plate is made of steel and the heating element is a thick film resistive tack component applied thereto.

In a fourth aspect, the present invention provides a carpet seaming iron having a base plate heated by an electrical element, the base plate having an enlarged longitudinal inverted - V - shaped groove extending substantially across the whole width of the base plate at the rear thereof.

In a fifth aspect, the present invention provides a method of temperature control for an electrical appliance including a plug for connection to a mains electricity supply, the method comprising a temperature sensor in the appliance in electrical connection with a control circuit in the plug, the control circuit including a user adjustable temperature regulator. The plug may also include a power supply unit if such is necessary for the appliance and/or the control unit. Preferably, the control circuit includes means for outputting an audible or visual alarm warning if the temperature of the appliance sensed by the sensor exceeds or falls below a predetermined value.

The control electronics can be incorporated in the handle of the appliance if there is sufficient space.

The above and other aspects of the present invention will now be described and explained in further detail, by way of example only, with reference to the accompanying figures in which: Figure 1 illustrates the conventional joining of two strips of carpet using hot melt adhesive seaming tape; Figure 2 illustrates the problem of tunnelling; Figure 3 shows in side view an embodiment of a heat shield in accordance with the first aspect of the invention; Figure 4 is a part plan view of the embodiment of Figure 3; Figure 5 illustrates, in a side view a and plan view b the result of premature cooling of hot melt adhesive; Figure 6 shows a part side view of an embodiment of a sole plate of a seaming iron in accordance with the second aspect of the present invention; Figure 7 shows a part crossection through a conyentional seaming iron a and one in accordance with the first and third aspects of the present invention b; Figure 8 shows a cross-sectional view along the line VIII in Figure 1; Figure 9 shows a similar view to that of Figure 8; but with a seaming iron in accordance with the third aspect of the present invention; Figure 10 shows partly the underside of a seaming iron in accordance with the fourth aspect of the present invention; Figure 11 is a cross-section along the line XI - XI in Figure 10, and Figure 12 illustrates a rear view of a low profile seaming iron.

Figure 13 is a block diagram showing a control system in accordance with the fifth aspect of the present invention; Figure 14 is an outline of the circuit diagram for the control system of Figure 13; and Figure 15 shows schematically views of a three-pin UK mains plug incorporating the control system of Figures 13 and 14.

In its first aspect, with reference to Figures 3,4 and 7, the present invention provides a carpet seaming iron having an upper a surface forming a heat shield 20 which, in use, engages and lifts the carpet as the iron is pushed between two pieces of carpet to be joined so that the hot plate of the iron gains access to the hot melt adhesive of the tape.

The upper surface is provided with a plurality of longitudinal ridges 21, preferably of semicircular cross-section. The ridges, being of sufficient size number and length, allow the passage of air between the iron and the carpet and at the same time reduce the surface area of contact between the iron and the carpet. The ridged upper surface can be provided integrally with the iron or provided as a demountable heat shield component.

Turning to Figures 5 and 6, the second aspect provides a seaming iron having a base 30 provided with a leading edge 31 raked at an angle of between 80" and 25 and including a transverse rebate or cutaway 32 at the lower leading edge of the base plate 30. Such an arrangement reduces the problem of premature cooling of the hot melt adhesive on the outside of the joint. As the iron passes along the hot melt adhesive tape, the leading edge of the base of the iron scoops up hot melt adhesive 35 in front of the iron see the side view in Figure Sa. This adhesive then tends to flow sideways round the edges of the iron, and form a ridge of adhesive running parallel to the sides of the iron, see the side view in Figure Sb. These ridges are then able to start cooling prematurely, and when the carpet is allowed back in contact with the adhesive tape, the first point of contact is with this cooled ridge which traps the carpet, before it can be flattened by post seam rolling.

The angle of inclination of the leading edge and the height and depth of the transverse rebate will be selected depending upon the viscosity of the hot melt adhesive used.

Figure 9 shows an embodiment of a seaming iron 5 in accordance with the third aspect of the present invention. The seaming iron 5 has a wafer thin heating element.

The heating element is typically produced by frame spraying a layer of metal oxide 51 between 20 - 150 microns thick onto a stainless steel sole plate 52, typically 3 6 mm thick. A suitable method for the manufacture of such elements is described in UK Patent No. GB 2,206,770.

The active, heating, part of a standard hot melt searning iron 40 (Figures 7a and 8) is of the order of 3 cm high or more because of using a conventional element 41 mounted within upper 42 and lower 43 aluminium castings. By using a thin film element this height can be reduced by 50% or more, resulting in far less deformation of the carpet around the seam (compare Figure 8 (conventional iron) and Figure 9).

An alternative sole plate can be manufactured by applying a thick film resistive track such as a printed circuit to a steel substrate. Reference is made to patent publications GB 2,272,226, WO96/17496 and W096/17497 and the references cited therein, for examples of such thick film resistive tracks.

Conventional seaming irons to assist in distribution of hot, melt adhesive across the seam have a base with a flat or grooved surface and frequently have a deeper central groove and various diagonal or v-shaped grooves such as is shown in GB 2,161,113 to manage the flow of hot melt adhesive from the rear of the iron. Figures 10,11 and 12 show a base plate of an iron in accordance with the fourth aspect of the present invention. A sole plate 52 has an enlarged longitudinal inverted V-shaped groove 60 at the rear of the iron, the groove extending substantially across the whole width of the sole plate 52. There may also be provided on either side of the enlarged groove, a channel 61 extending from the rear of the sole plate. These twin grooves may or may not be required, depending upon the viscosity of the hot melt adhesive.

Figure 12 is a view of the rear of a low profile seaming iron with the expected shape of hot melt adhesive 70 as it leaves the rear of the iron 60.

The existing methods of controlling any appliance which operates at a temperature higher or lower than the ambient air temperature of its location, is by means of a device, either mechanical or electronic, built into the appliance, and which may have provisions of some means of operator control of the temperature provided somewhere on the apparatus. These control devices may take the form of a thermostat, with a bimetallic strip to provide temperature control, or by means of a electronic sensor and electronic control circuit to achieve temperature control. Less common, but sometimes used, is a separate control box, connected to the appliance, in order to control the operating temperature. These are cumbersome, adding considerably to the weight and size of the iron, which can lead to the problems of tunnelling or peaking as described above.

In a fifth aspect, the present invention provides a method of temperature control of an appliance and is illustrated with reference to Figures 13 to 15. Control is achieved by the fitting of an sensor 100, which may be a thermistor or thermocouple or other electronic temperature sensing device, within the area of the appliance that requires temperature tontrol (such as adjacent the heating element 111), but the control apparatus (including optionally any necessary transformer) is provided in the mains electrical plug itself. This avoids undue bulk in the appliance itself, which can remain relatively small and lightweight. The number of cores or wires within the electric supply cable is increased from the usual number, typically three for live, neutral and earth, by an amount necessary, typically an additional two, to provide for the connection of a sensor, such as a temperature sensor in the appliance to the plug 112 provided for connection to the electrical supply. Figure 15 shows a plug suitable for connection to the UK mains system, comprising three square pins, live 113, neutral 114 and earth 115. Additional cores may also be added to provide for the inclusion of visual 125 or audible 126 indicating or warning devices within the appliance.

Alternatively such devices may be retained in the plug. The case of the plug 112 houses an electronic control circuit which may be built from discreet components, including a micro controller or other such device, or a dedicated integrated circuit design. The size of the plug casing may be enlarged as necessary to take the control apparatus. Temperature control setting may be predetermined in the design of the electronics, or by provision of buttons or a control knob 120 on the case of the plug.

In addition to this, light emitting diodes, or lamps may be included in the case of plug to indicate when the electric supply is connected, whether the appliance is changing temperature, or is at the required temperature. A liquid crystal display to provide the operator of the appliance with a numeric indication of the current temperature of the appliance. Alternatively electronic feedback could be used to provide similar information on an lcd screen on the appliance itself. Additional safety of the appliance can be provided by the inclusion of an earth leakage trip, residual current device, or circuit breaker within the body of the plug.

This fifth aspect of the present invention is applicable to any electrical appliance requiring temperature control whether by heating or cooling. It will find particular use, however, in the seaming iron described therein.

Removal of the thermostat provides extra space, which, when a conventional heating element is used, can be formed in such a way, that the overall length of the hot melt seaming iron may be reduced for up to 25 %, to provide a more manoeuvrable tool.

Preferably, the present invention provides a seaming iron comprising all the above features.

Claims

1. A carpet seaming iron having a base plate heated by an electrical element, an upper surface and a handle, wherein the upper surface forms a heatshield and is provided with a plurality of longitudinal ridges.

2. A carpet seaming iron as claimed in Claim 1 wherein the longitudinal ridges have a semicircular cross-section.

3. A carpet seaming iron as claimed in Claim 1 or Claim 2, wherein the heat shield is demountable.

4. A carpet seaming iron having a base plate heated by an electrical element and a handle wherein the base plate has a leading edge raked at an angle of from 80 to 250 and includes a transverse rebate at the lower leading edge of the base plate.

5. A carpet seaming iron having a base plate heated by an electrical element, wherein the heating element is a thin film of metal oxide of between 20 and 150 microns thickness upon a stainless steel sole plate.

6. A carpet seaming iron having a base plate heated by an electric element wherein the base plate is made of steel and the heating element is a thick film resistive tack component applied thereto.

7. A carpet seaming iron having a base plate heated by an electrical element, the base plate having an enlarged longitudinal inverted - V - shaped groove extending substantially across the whole width of the base plate at the rear thereof.

8. A carpet seaming iron as claimed in Claim 7 wherein the base plate further includes a longitudinal groove adjacent the inverted V-shaped groove on either side thereof.

9. A method of temperature control for an electrical appliance including a plug for connection to a mains electricity supply, the method comprising a temperature sensor in the appliance in electrical connection with a control circuit in the plug, the control circuit including a user adjustable temperature regulator.

10. A method of temperature control as claimed in Claim 10 wherein the control circuit includes means for outputting an audible or visual alarm warning if the temperature of the appliance sensed by the sensor exceeds or falls below a predetermined value.

11. A carpet seaming iron having a base plate heated by an electrical element, an upper surface and a handle; wherein the upper surface forms a heatshield and is provided with a plurality of longitudinal ridges; and wherein the base plate has a leading edge raked at an angle of from 800 to 250 and includes a transverse rebate at the lower leading edge of the base plate and an eniarged longitudinal inverted - V shaped groove extending substantially across the whole width of the base plate at the rear thereof.

12. A carpet seaming iron as claimed in Claim 11 including a plug for connection to a mains electricity supply and a temperature sensor in the appliance in electrical connection with a control circuit in the plug, the control circuit including a user adjustable temperature regulator and such a power supply unit as is necessary for the appliance and/or the control unit.

13. A carpet seaming iron as claimed in Claim 12 wherein the control circuit includes means for outputting an audible or visual alarm warning if the temperature of the appliance sensed by the sensor exceeds or falls below a predetermined value.