JP2017094400A - Contact tip used for gas metal arc - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact tip of long product life capable of obtaining a continuous and preferable electric contact in a vicinity of the outlet of a welding wire.SOLUTION: A contact tip of this invention comprises: a body 3 having a tubular base part and two or more fingers 5a, 5b extending axially from the front end of the base part; at least one wire feed duct 7, configured to receive and feed a weld wire, passing through the body to extend axially; slots 10a, 10b located between the fingers to make a space; and spring means 11, configured to make spring force act radially on the fingers, the spring means 11 applying no pressure on the casing surface of the weld wire introduced into the wire feed duct by maintaining a gap when the fingers are cool, and applying pressure radially inward on the casing surface of the weld wire under spring force when heated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a contact tip according to the preamble part of claim 1 for use in gas metal arc welding.

  In gas metal arc welding, the welding wire is fed through a wire feed conduit in the contact tip. It is made of a metal material having good electrical conductivity and forms a contact means for transferring the welding current to the welding wire fed through the contact tip. Gas metal arc welding is done with a welding wire either in the form of a solid wire or a powdered wire. In gas metal arc welding, an arc is maintained between the welding wire and the workpiece to be welded. Mag welding and MIG welding are two common gas metal arc weldings. In MAG welding, the arc and weld pool are protected by active shielding gas, and in MIG welding, the arc and welding pool are protected by inert shielding gas. In a gas metal arc, when welding with a welding wire in the form of a powdered wire, the welding can be performed without adding inert gas.

  Sliding the welding wire through the wire feed conduit in the contact tip toward the inner surface of the wire feed conduit provides the contact necessary to transfer power from the contact tip to the welding wire. In conventional contact tips, the wire feed conduit accepts the welding wire with a small gap, so the position of the contact point between the welding wire and the contact tip may change during the welding process, for example, Within the wire delivery conduit, unexpected and undesirable arcs can occur between the welding wire and the contact tip. Such sporadic arcing results in significant power loss resulting in overheating and tip wear. In addition, the welding wire may burn into the tip due to arcing and may need to be discarded. In addition, changing the position of the contact point between the welding wire and the contact tip changes the length of the welding wire through which the welding current flows, changing the characteristics of the arc between the welding wire and the workpiece. , Deteriorate the welding quality. The above-mentioned problems can be avoided by maintaining a continuous and favorable electrical contact between the welding wire and the contact tip in the region close to the outlet port of the wire delivery conduit. However, maintaining contact in this manner mechanically wears the welding wire at the inner surface of the wire delivery conduit, thereby increasing play between the welding wire and the inner surface of the wire delivery conduit. There is a possibility, and therefore there is a difficulty in impairing the electrical contact between the welding wire and the inner surface of the wire delivery conduit. Further, the wear on the inner surface of the wire feed conduit makes it difficult to adjust the welding wire at the outlet end of the wire feed conduit and deteriorates the welding accuracy. Contact tip life is shortened due to mechanical wear of the contact tip as a result of the occurrence of sporadic arcs in the wire delivery conduit. In order to stop the material cost and the interruption time associated with replacing a worn contact tip with a new one, it is preferable to extend the life of the contact tip.

Various solutions have been proposed over the years to ensure continuous and favorable electrical contact between the welding wire and the contact tip in the region near the outlet port of the contact tip wire delivery conduit. As examples of such a solution, for example, US Pat. No. 6,559,416B1, US Pat. No. 6,710,300B2, US 2011 / 0036821A1, and WO 2006 / 046799A1 are disclosed. However, since only a few solutions have been proposed and developed, it is far from commercial success and the above problem still requires a simple and efficient solution.
(Object of the present invention)
The object of the present invention is to provide a simple and effective contact tip with a favorable product life, so that under normal welding conditions, near the outlet port of the contact tip wire delivery conduit. A continuous and favorable electrical contact between the welding wire and the contact tip can be ensured.

  The object is achieved according to the invention by a contact chip having the features specified in claim 1.

The contact tip according to the present invention comprises:
A body of electrically conductive metallic material having a tubular base portion and two or more fingers coupled to the base portion and extending axially from the front end of the base portion A body characterized by
At least one wire delivery conduit extending axially through the body and adapted to receive and feed a welding wire into the conduit, the wire delivery conduit at the rear end of the contact tip A wire delivery conduit having an inlet port and having an outlet port between the fingers at the front end of the contact tip;
Slots between the fingers of the body for creating a space therebetween, each slot extending from a base portion of the body to the outlet port;
Spring means designed to wrap around the fingers and apply a spring force to the fingers in a radial direction, wherein when the fingers are cold, the spacing increases and the welding wire received in the wire feed conduit When applied to the casing surface of the welding wire received in the wire feeding conduit, when the pressure is not applied to the casing surface of the metal and heated to a temperature equal to or higher than the softening temperature of the metal material, a radius is applied by the spring force. Spring means characterized by applying pressure inward in the direction;
It comprises.

  With the solution according to the invention, the finger of the contact tip is pressed against the welding wire received in the wire feed conduit only when the contact tip is heated to a temperature above the softening temperature of the metal material. Such heating of the contact tip occurs automatically after welding is started because heat is generated during welding. During welding, when the contact tip exceeds the softening temperature of the metal material, the contact tip finger is elastic so that pressure is applied to contact the welding wire extending through the wire feeding conduit by the spring means. The contact tip fingers have. This ensures continuous and favorable electrical contact between the welding wire and the contact tip in the region near the outlet port of the contact tip wire delivery conduit during welding. . The welding wire action causes the inner surface of the wire delivery conduit to wear away during welding, so that the spring means gradually applies pressure to bring the fingers closer together, while in the region near the outlet port of the wire delivery conduit. Maintaining a continuous favorable electrical contact between the wire and the contact tip contributes to maintaining the preferred product life of the contact tip.

  When the contact tip cools, the contact tip fingers are stiff enough to resist the radial movement of the spring force of the spring means, so that prior to welding, the welding wire can be easily inserted without receiving resistance from the fingers The fingers can maintain a preferred distance spacing that can be advanced through the wire delivery conduit. Furthermore, the contact chip of the present invention has a simple design with few parts to be separated, and is relatively easy to manufacture and inexpensive.

  The spring means shall be a heat-resistant metal spring material that exerts a spring force in the radial direction on the finger of the contact tip with a substantially constant strength regardless of the temperature, provided that the softening temperature of the spring material is not exceeded. Alternatively, at low temperatures, a force exerted on the contact tip finger in the radial direction becomes a negligible value or zero, and a bimetal material made so that this value increases as the temperature increases can be obtained. In any event, the spring means should obviously be made of a spring material having a softening temperature that exceeds the softening temperature of the metal material of the contact tip body, and further, the contact tip generally exceeds the softening temperature during welding.

  Other advantageous features of the contact tip according to the invention will become apparent from the dependent claims and the following description.

The present invention will be described in more detail with reference to embodiments and the accompanying drawings. The following is shown in the drawing.
1 is a schematic perspective view of a contact chip according to an embodiment of the present invention. It is sectional drawing of the contact chip of FIG. 1 in a cold state. FIG. 2 is a cross-sectional view of the contact chip of FIG. 1 in a heated state. It is a front view of the contact chip of FIG. It is a diagram which shows the nominal hardness of a metal material when changing the temperature of a metal material.

  1-4 show a contact tip 1 according to an embodiment of the invention for use in gas metal arc welding with a welding wire 2 in the form of a solid wire or a wire with a core. The contact chip 1 comprises a body 3 made of an electrically conductive metal material, preferably in the form of a copper alloy for high temperature applications. The body 3 includes a tubular base portion 4 and fingers 5a and 5b coupled to the base portion extending in the axial direction from the front end of the base portion. The body 3 is further provided with a screw thread 6 at the rear end of the base portion 4. This thread 6 allows the contact piece 1 to be screwed firmly into the welding device. The base part 4 and the fingers 5a and 5b are integrated into one body.

  A straight wire feed conduit 7 extends body 3 axially along the central axis of the body. This wire feed conduit 7 has a welding wire 2 extending therein. The wire feed conduit 7 has an inlet port 8 at the rear end of the contact tip and an outlet port 9 between the fingers 5a, 5b at the front end of the contact tip. The wire feeding conduit 7 has a diameter slightly larger than the diameter of the welding wire 2, for example, about 0.1 to 0.2 mm, so that the welding wire 2 can be accommodated in the wire feeding conduit 7 with a small gap. Made to house the wire delivery conduit.

  Slots 10a and 10b are provided between the fingers 5a and 5b in the body 3 to divide the fingers 5a and 5b from each other, and each slot 10a and 10b extends from the body base portion 4 to the outlet port of the wire feed conduit 9. It extends in the axial direction. Each slot 10a, 10b extends radially between the wire feed conduit 7 and the outer surface of the body 3. The front portion of the body 3 is divided by slots 10a and 10b to form the fingers 5a and 5b. It is desirable that the axial length of each slot 10a, 10b corresponds to about 25-80% of the total length of the chip.

  The room for wear on the inner surface of the wire delivery conduit increases as the width w of the slots 10a, 10b increases. However, when the welding wire 2 advances between the fingers 5a, 5b, the width of the slot does not have to be so wide that it slides out of the wire feed conduit 7 and enters the slots 10a, 10b. Each slot 10a, 10b has a width w corresponding to 25 to 90 percent of the diameter d of the wire delivery conduit.

  In the illustrated example, the fingers 5a and 5b are two in number and are divided by two slots 10a and 10b provided on the opposite side so as to face the wire feeding conduit 7. Alternatively, the number of fingers 5a, 5b can be 2 or more, for example 3 or 4, which naturally increases the number of slots 10a, 10b.

  The contact tip 1 is attached with spring means 11 surrounding the fingers 5a and 5b. The spring means 11 is attached around the fingers at the front portions of the fingers 5a and 5b, and is accommodated in the groove 12 outside the fingers 5a and 5b. The spring means 11 preferably comprises a conventional spring, but can alternatively comprise a bimetallic element, for example a bimetallic element in the form of an open ring. In the example shown, the spring means 11 is constituted by a spiral spring in the form of an open ring, but can alternatively be constituted by a coil spring.

  When the spring means 11 is in a cooled state, for example, at room temperature or at another temperature sufficiently lower than the softening temperature of the metal material of the body, the welding wire 2 accommodated in the wire feed conduit 7 as shown in FIG. In order to prevent pressure from being applied to the casing surface of the fingers 5a and 5b, the fingers 5a and 5b are configured to apply a spring force to the fingers 5a and 5b in a radial direction with such a strength that the fingers maintain a distance from each other. When heated above the softening temperature of the metal material of the body, a radial force is applied by the spring force of the spring means so that pressure is applied to the casing surface of the welding wire 2 housed in the wire feed conduit 7 as shown in FIG. Pressed toward the inside. When the contact tip 1 is cold and below the softening temperature of the actual metal material, the spring means 11 fingers the welding wire 2 fed through the wire feed conduit 7 into the outlet port 9 of the wire feed conduit. 5a and 5b are not pressed. Therefore, it is not troublesome to introduce the welding wire 2 into the contact tip 1 when preparing a welding device prepared together with the contact tip for welding with the fingers 5a and 5b. Subsequently, when welding is started and the contact tip 1 is heated to a temperature exceeding the softening temperature of the metal material, the spring means 11 presses the fingers 5a and 5b and contacts the welding wire 2 introduced into the wire feed conduit 7. And thus ensure a continuous and good electrical contact between the fingers 5a, 5b and the welding wire 2 in the region adjacent to the outlet port 9 of the wire feed conduit.

  The softening temperature of the metal material is a temperature at which the hardness of the material starts to decrease as the temperature rises. The material maintains a substantially constant hardness until the material reaches the softening temperature of the material, but after being heated to the softening temperature, the material hardness decreases with increasing temperature. FIG. 5 is a diagram showing the nominal hardness as a function of temperature for a copper alloy having a softening temperature of 475.degree. As shown in the diagram of FIG. 5, the hardness of this material is substantially constant up to a temperature of 475 ° C. and thereafter decreases with increasing temperature.

  The spring means 11 is made of a metal spring material having a softening temperature exceeding the softening temperature of the metal material forming the contact tip body 3 and having a softening temperature equal to or higher than the temperature normally reached by the tip 1 when welding. In order to work properly in normal welding conditions, the spring material should have a softening temperature of 1500 ° C. or higher.

  The fingers 5a and 5b in the contact tip 1 shown in FIGS. 1 to 4 are designed to form a mating surface for a tool used to fix the contact tip to the welding device and remove the contact tip from the welding device. A hollow 13 is provided.

  In the illustrated example, the contact tip 1 is equipped with a single wire feed conduit 7. However, the contact tip according to the present invention can alternatively be equipped with two or more wire feed conduits extending through the base 4 and fingers 5a, 5b of the contact tip body 3 and extending parallel to each other. Each delivery conduit is made to receive a wire.

  Naturally, the present invention is in no way limited to the embodiments described above, but without departing substantially from the basic concept of the invention as defined in the appended claims. It will be apparent to those skilled in the art that there is a lot of room for correction.

Claims (11)

A contact tip used for gas metal arc welding, wherein the contact tip (1) is:
A body (3) made of an electrically conductive metal material, the body (3) being connected to the tubular base portion (4) and the base portion (4) from the front end of the base portion (4) A body (3) characterized by having two or more fingers (5a, 5b) extending in the axial direction;
At least one wire delivery conduit (7) extending axially through the body (3), adapted to receive and feed a welding wire, the wire delivery conduit (7) being located after the contact tip A wire feed conduit (7) characterized in that it has an inlet opening (8) at its end and an outlet port (9) between said fingers (5a, 5b) at the front end of the contact tip;
Slots (10a, 10b) provided between the fingers (5a, 5b) of the body (3) to separate the fingers (5a, 5b) from each other, each slot (10a, 10b) being Slots (10a, 10b), characterized in that they extend axially from the base part (4) of the body to the outlet port (9);
Comprising
The contact tip (1) has spring means (11) configured to surround the fingers (5a, 5b) and to apply a spring force to the fingers (5a, 5b) in a radial direction. In order to be able to adjust the casing surface of the welding wire in the wire feed conduit at a temperature lower than the softening temperature of the metal material, the fingers maintain a spacing and during the welding operation, the softening temperature of the metal material of the body The finger is pressed by a spring force applied radially inward to apply pressure to the casing surface of the welding wire received in the wire feed conduit (7) at a higher temperature,
Contact chip.   The contact tip according to claim 1, wherein the spring means (11) is fitted in a groove (12) provided outside the fingers (5a, 5b).   3. Contact tip according to claim 1 or 2, characterized in that the spring means (11) are constituted by a spiral spring in the form of an open ring.   The contact tip according to claim 1 or 2, wherein the spring means (11) comprises a coil spring.   The contact tip according to claim 1 or 2, wherein the spring means (11) comprises a bimetal element.   The said spring means (11) is made of a metal spring material having a softening temperature equal to or higher than the softening temperature of the metal material forming the contact tip body (3). Contact chip.   7. Contact tip according to claim 1, wherein the spring means (11) is mounted around the fingers (5a, 5b) at the front of the fingers (5a, 5b).   The fingers (5a, 5b) are two in number and are divided by two slots (10a, 10b) provided on the opposite side, facing the wire feeding conduit (7). The contact chip according to claim 1.   9. The contact tip according to claim 1, wherein each slot (10a, 10b) has a width (w) corresponding to 25-90% of the diameter (d) of the wire feed conduit. .   The contact chip according to claim 1, wherein the body is made of a copper alloy.   11. The force according to claim 1, wherein the radially inward force does not press the fingers so as to maintain the gap at a temperature lower than a softening temperature of the metal material of the body. Contact chip.

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