GB2064396A - Electric Soldering Iron - Google Patents

Abstract

An electric soldering iron has a longitudinal diametral slit (5) formed in a heat conducting element (3c) formed integrally with an iron portion (3) of the soldering iron. A flat plate- like heating element (2c) is fitted into and held in the slit. This structure simplifies a method of manufacturing the soldering iron, increases thermal efficiency, and reduces the size of the soldering iron. The heating element (2c) may comprise a ceramic element provided with a printed resistor pattern or a wire wound around an insulating plate and enclosed in mica. <IMAGE>

Description

SPECIFICATION Electric Soldering Iron This invention relates generally to an electric soldering iron, and more particularly to a device for heating an iron portion of the soldering iron.

Figure 1 A is a sectional front view of an essential part of a prior art electric soldering iron, and Figure 1 B is a sectional front view of an essential part of another prior art electric soldering iron. Both soldering irons are examples of soldering iron in which a ceramic heating element is used. The heating element is disposed in a heat conducting element in a relation of the former element being in contact with the latter element in a longitudinal extent of the conducting element, the heat conducting element being formed integrally with an iron 3 longitudinally of the iron and being made of a metal excellent in heat conductivity.Namely, the soldering iron shown in Figure 1 A is constructed in the manner that a ceramic heating element 2a made of a generally hollow cylindrical body is enclosed concentrically in a metal sheath 1 and that a round rod-like heat conducting element 3a is fitted into the hollow portion of the heating element 2a and is in contact with the heating element 2a so as to heat by Joule effect the heating element 2a to thereby heat the heat conducting element 3a by energising lead wires 4 connected to terminals (not shown) provided in the heating element 2a. In this case, a printed heat-generating resistor pattern (not shown) used in terms of the above heating element 2a is formed within the wall thickness of the ceramic cylindrical body.In contrast thereto, the electric soldering iron shown in Figure 1 B is constructed in such a manner that the heating element 2b is formed in a round rod-like or a hollow cylindrical body and is inserted into the cavity of the hollow cylindrical heat conducting element 3b so that the element 2b may be in contact with the element 3b. In the latter embodiment, the heating element 2b is not essentially different in structure from the preceding embodiment, and for particulars about the heating elements of the kind described above, refer to U.S. Patent No. 4035613 and its accompanying drawings.

The structure of the prior art electric soldering irons is as described above, and the cylindrical and rod-like ceramic heating elements 2a and 2b are characterised in that they are high in mechanical strength in themselves and compact in size. But they have the counterbalancing disadvantage in the methods of manufacturing them, namely, the disadvantage that the elements 2a and 2b are manufactured in such a manner that after a heat-generating resistor pattern, which provides a resistance value necessary for the electric soldering iron, has been printed on the opposed surface of either one of a pair of upper and lower base plates made of ceramic sheet as of alumina, beryllium or the like, the base plates are laminated in an upper and lower pair and formed into a cylindrical or a rod-like shape so as to have the specified outer and inner diameters and are calcined, which makes the heating elements 2a and 2b to be more complicated in the step of manufacturing, lower in yield rate, and higher in cost than a plate-like electric heating element. Another disadvantage is in that in inserting the heating elements 2a and 2b as described above into the heat conducting elements 3a and 3b, both heat expansion and difficulty in manufacturing them make the heating elements 2a and 2b unable to be mounted therein in such a manner that the heat conducting elements 3a and 3b are brought into a completely tight contact with the ceramic heating elements 2a and 2b.Accordingly, the heat which is generated from the ceramic heating elements 2a and 2b is not sufficiently transferred to the heat conducting elements 3a and 3b, with the result that heat loss becomes greater and a longer rise time is required for the soldering iron to attain the temperature high enough to make soldering possible after energization of the heating elements.

The present invention provides an electric soldering iron comprising a heat conducting element formed integrally with an iron portion of the soldering iron longitudinally of the iron, a diametrical slit formed across the element and along the length of the element from the rear end thereof, and a plate-like heating element inserted into the slit and held in the same.

A description of a preferred embodiment of the invention will now be given with reference to the accompanying drawings, in which: Figure 1 A is a sectional front view of an essential part of a prior art electric soldering iron, Figure 1 B is a sectional front view of an essential part of another prior art electric soldering iron, Figure 2A is a sectional front view showing, in part, an electric soldering iron according to the invention, Figure 2B is a perspective view showing, in disassembled form, an essential part of the electric soldering iron according to the invention.

Both in Figures 2A and 2B and in Figures 1A and 1 B, parts corresponding to each other are indicated by corresponding reference characters respectively. In the soldering iron of the invention, as shown in Figures 2A and 2B, a heat conducting element 3c formed integrally with an iron portion 3 in a longitudinal direction of the iron portion is built into a metal sheath 1, and a slit 5 opening diametrically of the heat conducting element 3c is continuously formed longitudinally from the terminal end of the heat conducting element 3c to an area in the neighbourhood of the front end of the element 3c, and a plate-like heating element 2c is inserted into and held in the slit 5.As the plate-like heating element 2c is preferably used a plate-like ceramic heater made in such a manner that a specified heat-generating resistor pattern is printed on a green ceramic sheet, and further another green ceramic sheet is laid over the printed green ceramic sheet or the printed ceramic sheet is covered with an insulating coating layer and the material thus obtained is subsequently calcined. But in addition to the heater of the type described above, a sheet-like electric wire heater may be used in which nichrome wire is wound around an insulating plate and covered insulatively with a mica plate.

Furthermore, for further particulars of the plate-like ceramic heater, refer to the Japanese Patent Publication No. 10,527/1977 and West German Laid-open Patent No. 2,548,019.

As a preferred embodiment of the slit 5 is shown a thoroughly split opening located diametrically of the heat conducting element 3c, but optionally, one end of the slit 5 may be open as shown or the other end of the slit 5 may be closed inside the heat conducting element 3c. In short, the slit 5 may be provided either in such a form as to have a certain degree of elastic retentive power of holding the heater 2c therein and cause the slit 5 to make slightly larger heat expansion than the heater 2c when the heat conducting element 3c is thermally expanded or in such a form as to function tog permit or absorb a normal heat expansion difference between the heater 2c and the heat conducting element 3c by utilising the space of the slit 5 wide enough to permit the free insertion of the plate-like heater 2c. In Figures 2A and 2B, the reference numeral 4 indicates lead wires.The plate-like heating element 2c is inserted into and held in the slit 5 of the heat conducting element 3c formed integrally with the iron portion 3.

Accordingly, the heat generated by the heating element 2c is transferred at a high rate of thermal efficiency from both surfaces of the heating element 2c through the holding surfaces of the heat conducting element 3c to the iron portion 3.

Also, because the heat conducting element 3c is thermally expanded, resulting for example, in making also the slit 5 wider in space in such a manner that the plate-like heating element 2c inserted into the element 3c is in slight contact with the element 3c, which results in less heat loss.

The described improvements in thermal efficiency makes it possible to minimise the size of both the heating element 2c and heat conducting element 3c with respect to the same quantity of heat produced.

Furthermore, there are the advantages that with a ceramic heater as the plate-like heating element 2c, high thermal efficiency through smaller watt consumption than the conventional type results in not only short rise time necessary for the element to attain the temperature to which the soldering iron is heated to make soldering possible after energisation, requiring only about three minutes which is as short as half of six to seven minutes conventionally required, but also excellent productivity low price and high durability and that the heat-generating resistor pattern makes sudden increase in resistance with rise in temperature, reduces an electric current and automatically suppresses power consumption, functioning to keep the temperature substantially constant.

Claims (6)

Claims

1. An electric soldering iron comprising a heat conducting element formed integrally with an iron portion of the soldering iron longitudinally of the iron, a diametrical slit formed across the element and along the length of the element from the rear end thereof, and a plate-like heating element inserted into the slit and held in the same.

2. An electric soldering iron according to claim 1 wherein said slit is thoroughly split open diametrically of said heat conducting element, the front end of said slit terminating in the neighbourhood of the front end of said heat conducting element.

3. An electric soldering iron according to claim 1 or claim 2 wherein said plate-like heating element is a calcined ceramic plate-like heating element containing a printed heat-generating resistor pattern within the thickness of the element

4. An electric soldering iron according to claim 1 or claim 2 wherein said plate-like heating element is made in such a manner that nichrome wire is wound around an insulating plate and the wire and plate are thereafter covered insulatively with a mica plate.

5. An electric soldering iron according to any one of the preceding claims wherein the heat conducting element is held in a metal sheath.

6. An electric soldering iron substantially as described herein with reference to Figures 2A and 2B of the accompanying drawings.