Title of Invention

"REEL WIRE TYPE OF WELDING DEVICE FOR SPOT WELDING OF A VEHICLE"

Abstract

A reel wire type of welding device for spot welding of a present invention includes a first guiding portion rotatably mounted in a front end of the welding device such that a wire is supported and guided thereby in a working area in which the wire contacts a target object, and at least one second guiding portion mounted in a rear of the roller such that the wire is supportedly guided in a zigzag manner being pressed in both upward and downward directions.

Full Text

FIELD OF THE INVENTION Generally, the present invention relates to a reel wire type of welding device for spot welding of a vehicle. More particularly, the present invention relates to the reel wire type of welding device in which wire guiding becomes more stable and abrasion and replacement timing of wire are automatically sensed. BACKGROUND OF THE INVENTION A reel wire type of welding device for spot welding of a vehicle has been proposed and published as Korean patent No. 337502, by the same inventor as of the present invention. Such a welding device is re-formed from one according to the prior art that has an electrode fixedly inserted as a tip at a shank portion of a welding device. In more detail, as shown in FIG. 1, such a welding device includes a working unit, a wire 200', a first reel 210', and a second reel 220'. The working unit includes a main body 110' and a support portion 111'. The wire 200' is made up of a Cr-Cu series alloy that is frequently used for spot welding. The first reel 210' unrolls the wire 200' and guides the wire 200' to the working unit, and the second reel 220' rolls the wire 200' received from the working unit. According to such a spot welding scheme, mutually contacting parts are welded by localized heating. According to such a scheme, as shown in FIG. 1, after overlapping plates to be welded, a high current flows to the plates by two overlapping welding devices through the wire. However, according to such a welding device, if tension between the two reels 210' and 220' is lost, the wire becomes loosened and unrolled. Therefore, in this case, the wire may lose direct contact with the plate such that no current flows between the wire and the plate. The welding is therefore not properly completed, and trouble may be caused by a nonconductive support portion coming into contact with the plate. The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention, and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known in this country to a person of ordinary skill in the art. SUMMARY OF THE INVENTION The motivation of a present invention is to provide a reel wire type of welding device for spot welding of a vehicle, having non-limiting advantages of better stableness in guiding a wire and ability to sense an abrasion and replacement timing of wire. An exemplary reel wire type of welding device for spot welding of a vehicle according to an embodiment of the present invention comprising a first guiding portion rotatably mounted in a front end of the welding device such that a wire is supported and guided thereby in a working area in which the wire contacts a target object, and at least one second guiding portion mounted in a rear of the roller such that the wire is supportedly guided in a zigzag manner being pressed in both upward and downward directions. In a further embodiment, a plurality of optical sensors for sensing a condition of the wire are further included. In another further embodiment, a position detecting sensor for sensing wire abrasion is further included. Such a position detecting sensor includes an elastic spring and a variable resistor element such that wire abrasion is measured by a change of resistivity of the variable resistor element caused by a lengthwise deformation of the elastic spring. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention, wherein: FIG.1 is a schematic view of a welding device according to the prior art; FIG. 2 is a perspective view of a welding device according to an embodiment of the present invention; FIG. 3 is an enlarged lateral view of a roller portion of a welding device according to an embodiment of the present invention; FIG. 4 is an enlarged perspective view of a position detecting sensor of a welding device according to an embodiment of the present invention; and FIG. 5 is a cross-sectional view of the position detecting sensor and its circumstances with respect to a welding device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFEPRRED EMBODIMENTS An embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings. FIG. 2 is a perspective view of a welding device 10 according to an embodiment of the present invention. The welding device 10 according to an embodiment of the present invention includes a main body 2 0, an adapter 22, and a support portion 24. The main body 20 is extended from a main portion (not shown). The adapter 22 is cylindrically extended from a front of the main body 20, while the support portion 24 is extended from a front of the adapter 22. The wire 200 is supplied in a direction shown by arrows and wound by a reel (not shown). Such an above-described scheme of a welding device is effectively the same as that of the prior art. Characterizing features of the present invention, a wire guiding device according to an embodiment of the present invention includes a roller 26, two guiding portions 30, and two guiding portions 30'. The roller 26 is formed in a front end of the support portion 24 and functions as a guiding portion. The two guiding portions 30 (hereinafter called front guiding portions) are disposed in front of sides of the main body 20. The two guiding portions 30' (hereinafter called rear guiding portions) are disposed in a rear of the sides of the main body 20. The roller 26 is rotatably connected at the front end of the support portion 24 by the rotating pin 26'. As shown in FIG. 3, the roller 26 is hollowed out at a central part thereof, to form a guiding groove 28. The guiding groove 28 is for supporting and guiding the wire 200. The front guiding portions 30 are formed with a low height, and the rear guiding portions 30' are formed with a high height. Such an arrangement produces merits such that the wire may be maintained at a high and constant tension, since the wire is guided in a zigzag manner being pressed in both upward and downward directions. In addition, a formation of rollers 300 and 300' formed in the guiding portions 30 and 30' is the same as that of the roller 26. The front guiding portions 30 are respectively provided with two confronting plates 32, a rolling pin 34, and a roller 300. The rolling pin 34 is tightly fitted into an upper part of the confronting plates 32, and the roller 300 is rotatably mounted on the rolling pin 34. The formation of the rear guiding portions 30' is almost the same as that of the front guiding portion 30. But confronting plates 32' of the rear guiding portions 30' are higher than the confronting plates 32 of the front guiding portions 30. In addition, a position detecting sensor 50 is located between the two confronting plates 32', which is described later in detail. According to such scheme for guiding a wire, the wire changes direction at the roller 26, and is supported by the guiding portions 30 and 30' in both upward and downward directions. Therefore, differently from the prior art, escaping of the wire is prevented since the wire is guided by the rollers, and problems of defective welding caused by derailment of the wire and of mechanical trouble of the support portion are prevented. In addition, there are merits in that the roller 26 can prevent damage to the wire by friction and that the roller 26 dissipates the heat generated by welding. According to an embodiment of the present invention, a wire-cut detecting device is further adopted, and it includes two optical sensors 40 mounted in the main body 20. The wire-cut detecting device is mounted between the front guiding portions 30 and the rear guiding portions 30'. As shown in FIG. 2, one optical sensor 40 is mounted on one side of the main body 20, and the other optical s ensor 40 is mounted on the other side thereof. Each of the optical sensors 40 includes a light emitting portion, a light receiving portion, and a transmitting portion, and is electrically connected to a pressure welding controller (not shown). Since the light emitting portion and the light receiving portion of the optical sensors 40 face the wire 200, the sensor 40 can transmit a light signal to and receive the same from the wire. Because such optical sensors 40 are already known to a person of ordinary skill in the art, details thereof are not described in further detail herein. If the light emitted from the light emitting portion of the optical sensor 40 is not reflected by the wire 200, the light receiving portion cannot sense the light reflected therefrom. In this case, the controller preliminarily determines that the wire is cut. However, non-detection of the light of the light receiving portion may accidentally happen by reduction and diffusion of light emitted from the sensor 40. In order to avoid such an error, it is preferable that signals from both sensors 40 disposed on both sides of the main body 20 are compared, and then the wire is determined to be cut in the case that a difference between light signals of the both sensors 40 is larger than a predetermined level or when a light signal is not received from either sensor 40. As shown in FIG. 4, a wire abrasion sensing device includes a position detecting sensor 50 mounted between the two plates 32' of guiding portion 30'. Obviously, such a wire abrasion sensing device may be mounted in a plurality of positions. An embodiment of a scheme of the position detecting sensor 50 will be hereinafter described in detail with reference to FIG. 5. The position detecting sensor 50 includes an elastic spring 58 and a variable resistor element 56 internally mounted in an upper case 52 of the position detecting sensor 50. The elastic spring 58 supports a bottom of the upper case 52 of the position detecting sensor 50. An output value of the variable resistor element 56 in the position detecting sensor 50 is changed by the height of the position detecting sensor 50 above the main body 20. Such a position detecting sensor 50 is known to a person of ordinary skill in the art, and is not described in further detail herein. The upper case 52 is electrically connected to the pressure welding controller by a signal line (not shown). An upper side of a roller on the upper case 52 of the position detecting sensor 50 faces the roller 300' of the rear guiding portion 30', and a predetermined clearance d is formed between the upper case 52 of the position detecting sensor 52 and the roller 300'. The wire 200 is guided through the clearance d. As the abrasion of the wire 200 increases, the clearance d becomes narrower and the elastic spring 58 gradually expands upwards. Therefore, the position detecting sensor 50 moves upwards and the resistivity of the variable resistor element 56 is varied in accordance with the change of the height of the position. If an electric current value of the circuit which includes the resistor is lower than a predetermined value (e.g., 50% of the initial value), the controller determines that the abrasion of the wire 200 has reached a limit value. Subsequently, it relays the result to workers through a display or alarm. The position detecting sensor 50 of an embodiment of the present invention supports a lower side of the wire 200. Therefore, it also has a function of supporting the tension of the wire, in cooperation with the roller 300'. As a variation of the present embodiment, the variable resistor element 56 of the wire abrasion sensing device can be replaced with, e.g., a piezoelectric element. In addition, the electric sensor 50 can be replaced with a display device that can capture an image of the wire such that a thickness of the wire may be determined therefrom. An embodiment of the present invention can be further changed without losing the technical features of enhanced guiding of a wire, detecting of a wire-cut, and detecting of maintenance timing due to an abrasion of the wire. That is, the scope of the present invention is not limited by the above-described details of positions, structure, and the number of the guiding portions and optical sensors, or the internal structure of the position detecting sensor. According to an embodiment of the present invention, escaping or derailment of a wire is prevented, and spot welding for a vehicle becomes more effective. In addition, a wire-cut and excessive abrasion of the wire may be automatically detected, and thus a worker may be apprised of causes of abnormal welding. Therefore, the welding process becomes more stable and efficient. While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. I/We Claim 1. A reel wire type of welding device for spot welding of a vehicle Comprising: - a first guiding portion rotatably mounted in a front end of the welding device such that a wire is supported and guided thereby in a working area in which the wire contacts a target object and - at least one second guiding portion mounted in a rear of the roller such that the wire is supportedly guided in zigzag manner being pressed in both upward and downward directions. 2. The welding device as claimed in claim 1, comprising a plurality of optical sensors for sensing a condition of the wire. 3. A welding device as claimed in claim 1 or 2 comprising a position detecting sensor for sensing wire abrasion, the position detecting sensor comprising an elastic spring and a variable resistor element such that the wire abrasion is measured by a change of resistivity of the variable resistor element caused by a lengthwise deformation of the elastic spring. 4. A reel wire type of welding device for spot welding of a vehicle substantially as herein described with reference to the ccompanying drawings.

Documents:

1142-del-2004-abstract.pdf

1142-del-2004-claims.pdf

1142-del-2004-complete specification (as files).pdf

1142-del-2004-complete specification (granted).pdf

1142-del-2004-correspondence-others.pdf

1142-del-2004-correspondence-po.pdf

1142-del-2004-description (complete).pdf

1142-del-2004-drawings.pdf

1142-del-2004-form-1.pdf

1142-del-2004-form-19.pdf

1142-del-2004-form-2.pdf

1142-del-2004-form-3.pdf

1142-del-2004-form-5.pdf

1142-del-2004-gpa.pdf

1142-del-2004-petition-137.pdf

1142-del-2004-petition-138.pdf