Background of the Invention Generally, the electric soldering iron is used for electric coupling of parts by heating the tip portion of the soldering iron and melting solder thereon.

The soldering operation is achieved by using both hands. In other words, an operator grips the soldering iron with one hand and supplies solder with the other hand. Such operation is not advantageous in that since the operator should use both hands, he is not able to hold the part properly. Thus, efficient of the operation is lowered.

There have been some proposals for solving the disadvantages for using both hands.

For example, Korean Patent Laid-open Gazette No. 2000-51320 and 2000-42681 disclose the soldering iron.

Referring to the disclosures, the solder iron has a shape of a pistol. When the operator pulls a trigger-type lever, a taken-up threadlike solder can be supplied by the action of links and gears. The threadlike solder contacts to the tip portion and melts thereon.

Here, the threadlike solder should pass through a heated nozzle to be melted. Therefore, it is not easy for the threadlike solder to pass through the heated nozzle. Further, even though passing through the heated nozzle, at least a portion of the threadlike solder remains within the heated nozzle, leading to clogging of the nozzle.

Summary of the Invention Thus, an object of the present invention is to provide an electric solder iron in which the operator pushes the tip portion of the electric iron onto a designated location, then the threadlike solder can be supplied from the threadlike supplying part connected to the tip portion.

The other object of the present invention is to provide an electric solder iron in which the operator pushes the tip portion of the electric iron onto the designated location, then the threadlike solder can be supplied from the threadlike solder supplying part having the leaf spring installed therein.

The another object of the present invention is to provide an electric solder iron in which the operator pushes the tip portion of the electric iron onto the designated location, then the threadlike solder can be supplied from the threadlike solder supplying part by the action of ratchet and gear.

In order to achieve these objects described above, the present invention provides the electric soldering iron comprising a tip portion installed in a case of the electric soldering iron; and threadlike solder supplying device connected to a heat insulating device installed on the tip portion.

Detailed Description of the Preferred Embodiments The preferred embodiments of the electric solder iron according to the present invention will be detailed referring to the attached drawings. Figures 1 to 4 show a first embodiment of the present invention. Figures 5 to 8 show a second embodiment of the present invention.

Referring to Fig. 1 to 4, the electric solder iron 10 comprises a heating device 12 installed in a case 1 extended from a handle 10; a tip portion 13 into which the heating device 12 is inserted; and a heat-insulating connector 14.

An end of the heat-insulating connector 14 is connected with a threadlike solder supplying part 20 through a slot 15 formed in the case 1.

A spring 21 is arranged at an end of the threadlike solder supplying part 20, thus the heat insulating connector 14 is elastically biased. The inner side of the heat-insulating connector 14 is threaded with a supporting body 22. Further, the supporting body 22 is threaded with a casing 23.

A grip piece 24 for gripping the thread-like solder is installed inside of the supporting portion 22. A chuck ring 25 is installed around the periphery of the grip piece 24. When the chuck ring 25 is released from the grip piece 24, the grip piece 24 opens and does not grip the threadlike solder extended therethrough. To the contrary, when the chuck ring 25 is positioned around the periphery of the grip piece 24, the grip piece 24 closes and grips the threadlike solder.

A thread-like solder guide tube 30 is disposed at the other end of the threadlike solder supplying part 20 such that the threadlike solder is guided and positioned at the end of the tip portion 13 thereby.

The electric solder iron of the present invention will be operated as described below.

When an operator holds the handle 11 and pushes the end of the tip portion 13, the tip portion will be moved backward. Here, the heat insulating connector 14 installed at the end of the tip portion 13, the supporting body 22 screwed with the heat insulating connector 14 and the casing 23 will be moved backward together with the threadlike solder guide tube 30, as shown in Fig. 4. As the supporting body 22 and the casing 23 are moved backward, the chuck ring 25 will be moved backward. Thus, the chuck ring

25 is released from the grip piece 24, so that the grip piece 24 opens.

In this state, when the operator releases the force that has been exerted on the tip portion 13, the threadlike solder supplying part 20 and the tip portion 13, which are connected to the heat insulating connector 14, move forward by means of the elastic force of the spring 21 disposed at the end of the threadlike supplying part 20, as shown in Fig. 3. Here, the chuck ring 25 moves forward and comes to engage with the grip piece 24 which has been opened, the grip piece 24 closes and grips the threadlike solder extended therethrough. Then the grip piece 24 move forward with a predetermined distance. By doing so, the grip piece 24 can cause the threadlike solder to move forward with a predetermined distance. As a result, the end of threadlike solder moves out of the threadlike solder guide tube 30 and is located at the end of the tip portion 13.

The length of threadlike solder coming out of the threadlike solder guide tube 30 corresponds to the backward distance of the tip portion 13 moved by the operator's hand. Also, the spring 21 has such an elasticity as the operator can push the tip portion 13 without strong resistance.

Second embodiment of the present invention is shown in Figs. 5 and 6. Referring to Figs. 5 and 6, the heat insulating connector 14 is connected with the end of the threadlike solder supplying part 20. At one side of the heat insulating connector 14, a supporting portion 41 and the spring 21 are disposed sequentially. Thus, the supporting portion 41 is supported at one end of the spring 21. The supporting portion 41 includes a leaf spring 40 formed as a piece 40-lwith a hole in the centre. The threadlike solder 100 extended through the hole of the leaf spring 40. As can be understood from the drawings, the plane of the leaf spring 40 is inclined forward to the tip portion 13. Thus, when the supporting portion 40 moves forward toward the tip portion 13, the leaf spring 40 grips the threadlike solder] 00 within the hole thereof, thus the threadlike solder 100 can be moved forward. To the contrary, when the supporting portion 40

moves backward, the leaf spring 40 does not grips the threadlike solder 100 in the hole thereof and only drags along the surface of the threadlike solder 100, thus the latter can not be moved. At the other end of the spring 21, a piece 42 for anti-reverse motion is located. The piece 42 for anti-reverse motion has also a leaf spring similar to the leaf spring 40.

When the operator pushes the tip portion 13 of the electric solder iron, the heat insulating connector can be moved backward together with the tip portion 13. Then, the supporting portion 41 and the leaf spring 40 are moved backward with a predetermined distance. Here, since the leaf spring 40 is inclined forward as stated above, the backward movement of the spring 40 does not move the threadlike solder 100.

However, when the operator releases the force on the tip portion 13, the leaf spring 40 is moved forward together with the heat insulating connector 14 by the force of the spring 21. Here, the leaf spring 40 grips the threadlike solder 100 in the hole thereof and moves the threadlike solder 100 forward toward the tip portion. As a result, the threadlike solder 100 travels through the threadlike solder guide tube 30 and can be positioned at the end of the tip portion 13.

Third embodiment of the present invention is shown in Figs. 7 and 8. Referring to the drawings, a ratchet 52 is connected to one end of the heat insulating connector 14. The ratchet 52 is engaged with a gear 54 located at one side of a roller 53. The gear 54 and the roller 53 have a common axis of rotation. The heat insulating connector 14 is elastically supported by a spring 50. Thus, the spring 50 is biased forward toward the tip portion 13. Further, the ratchet 52 is biased toward the teeth of the gear 54 by a spring 51. The threadlike solder 100 passes between a roller 53 and a pressing plate 55and extends through the threadlike solder guide tube 30.

When the operator pushes the tip portion 13, the heat insulating connector can be moved backward. Thus, the ratchet 52 engaged with the teeth of the gear 54 can rotate

the gear 54. At the same time, the roller 53 can be rotated. Because the threadlike solder 100 is pressed between the surface of the roller 53 and the pressing plate 55, the rotation of the roller 53 causes the threadlike solder to move forward. Thus, the threadlike solder 100 can be located at the end of the tip portion after passing through the threadlike guide tube 30. However, because the engagement of the ratchet 52 with the gear 54 is released during the forward movement of the heat insulating connector 14, the threadlike solder 100 is not moved during the forward movement of the heat insulating connector 14.

As stated above, the present invention is advantageous in that the threadlike solder can be moved forward with a predetermined distance toward the end of the tip portion merely by pushing the tip portion. Thus, the operator can use the electric solder iron only with one hand.