1. Field of the Invention
The present invention relates to a welding torch used for gas-shielded arc welding.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 10-328836 (Claims and FIGS. 1 and 2) discloses a welding torch of a gas-shielded arc welding apparatus in which a contact tip (hereinbelow, a “tip”) that supplies electric current to a welding wire extending therethrough is provided at a distal end portion of a tip body (a “contact tip holder” in Japanese Unexamined Patent Application Publication No. 10-328836), which is removably attached to a torch body.
Conventionally, a welding wire is fed to a welding torch, passes through a torch body and a tip body, and is fed out of a tip. Electric current is supplied from a power source to the tip and the welding wire, whereby welding is performed. Because the tip is gradually worn away due to friction with the welding wire during the welding operation, the tip needs to be replaced depending on the amount of wear.
Once the tip is worn away, a gap is produced between the tip and the welding wire passing therethrough, resulting in poor contact between the tip and the welding wire. To solve the problem of poor contact, in the welding torch disclosed in Japanese Unexamined Patent Application Publication No. 10-328836 (Claims and FIGS. 1 and 2), the welding wire is urged in a direction perpendicular to the axial direction by a cushioning rubber spacer.
Furthermore, to solve the problem of poor contact, in a welding electrode disclosed in Japanese Unexamined Patent Application Publication No. 4-143077 (Claims and FIGS. 1 and 4), a tip (a “current supply device” in Japanese Unexamined Patent Application Publication No. 4-143077) is urged toward the axis by a contact control cylinder provided radially outward of a welding wire.
Furthermore, in a gas metal arc (GMA) welding method disclosed in Japanese Unexamined Patent Application Publication No. 2010-194566 (Claims and FIGS. 1 and 2), the amount of spatter is reduced during welding to achieve stable welding. Therein, pulsed electric current is allowed to flow between a contact electrode and a work piece, and constant electric current, i.e., electric current controlled at a constant level, is allowed to flow between the work piece and an additional contact electrode in contact with the welding wire. The additional contact electrode is in contact with the welding wire at a position closer to the work piece than the contact electrode.
The welding torch disclosed in Japanese Unexamined Patent Application Publication No. 10-328836 (Claims and FIGS. 1 and 2) can solve the problem of poor contact between the tip and the welding wire. However, when arc welding is performed with high electric current, the tip is heated by the resistance between the tip and the welding wire and is worn away quickly, increasing the tip-replacement frequency. Furthermore, increased tip-replacement frequency lowers the operation efficiency because the welding operation is often interrupted.
In the welding electrode disclosed in Japanese Unexamined Patent Application Publication No. 4-143077 (Claims and FIGS. 1 and 4), a plurality of current-supply-device segments are provided on the outer periphery of the welding wire, and the contact control cylinder and an urging roller for urging the current-supply-device segments are provided on the outer side of the current-supply-device segments. This configuration significantly increases the size of the welding torch in the width direction (a direction perpendicular to the axial direction). Furthermore, with such a large welding electrode, the welding area during welding is limited due to the presence of the contact control cylinder and the urging roller.
Although the GMA welding method disclosed in Japanese Unexamined Patent Application Publication No. 2010-194566 (Claims and FIGS. 1 and 2) suggests division of a current supply point, the method is not practical because no specific structure is disclosed therein, and support structures for the tips or the ease of replacement of the tips are not considered. More specifically, for example, from a method illustrated in FIG. 1 of Japanese Unexamined Patent Application Publication No. 2010-194566, it seems that a lower current-supply tip 3 is integral with a tip body and is not replaceable. Such a configuration requires the whole unit to be disassembled when an upper current-supply tip 2 or the lower current-supply tip 3 is replaced due to inevitable wearing or adhesion to the wire, and is time and effort consuming. Accordingly, this method has little practical use. In addition, a method illustrated in FIG. 2 of Japanese Unexamined Patent Application Publication No. 2010-194566 does not disclose the details of how an electric current-supply tip 92 is supported at three positions, how it is supplied with electric current, or how it is replaced. Accordingly, this method is no longer just an idea.
The present invention has been made in view of these circumstances, and an object thereof is to provide a compact welding torch with reduced tip wear, reduced tip-replacement frequency, and improved tip-replacement efficiency.
To solve the above-described problems, a welding torch of the invention includes: a torch body having a wire path through which a welding wire extends along an axis portion, a gas supply path through which gas from a gas source is supplied, and a current supply path through which electric current from a power source is supplied; a nozzle having a gas ejection port at a distal end portion thereof through which gas is discharged, the torch body being mounted to a base end portion of the nozzle, the welding torch discharging gas from the gas ejection port to weld a work piece using the welding wire; a first tip body provided inside the nozzle and electrically connected to the torch body, the welding wire, the gas, and the current being supplied to the first tip body through the torch body; a first tip provided at a distal end of the first tip body to supply the current having passed through the first tip body to the welding wire; an insulating bushing formed of an insulative material and disposed on an outer periphery of the first tip body inside the nozzle; a second tip body accommodating the first tip body with the insulating bushing interposed therebetween, the second tip body being supplied with electric current from the power source; and a second tip provided at a distal end of the second tip body to supply the current having passed through the second tip body to the welding wire, the welding wire extending through the first tip being inserted therethrough. The first and second tips are axially arranged, in two stages, at a predetermined distance from each other and supply electric current to the welding wire.
With this configuration, the first and second tips are axially arranged, in two stages, at a predetermined distance from each other and supply electric current to the welding wire. By providing two current supply points in the axial direction, the current supplied to each of the first and second tips is reduced. Thus, the amount of heat generated by the tips, the amount of tip wear, and the tip-replacement frequency can be reduced, thereby improving the welding and tip-replacement efficiencies. At the same time, the size of the entire welding torch can be reduced.
Furthermore, it is preferable that the first tip body have a first hollow portion through which gas flowing out of the torch body flows and a first communication hole provided in an outer periphery of the first tip body so as to communicate with the first hollow portion, that the second tip body have a second hollow portion through which gas flowing out of the first communication hole flows and a second communication hole provided in an outer periphery of the second tip body so as to communicate with the second hollow portion, and that a third gas flow path communicating with the second communication hole and the gas ejection port be defined between the outer periphery of the second tip body and an inner wall of the nozzle.
With this configuration, the gas supplied to the torch body flows from the first hollow portion in the first tip body to the second hollow portion in the second tip body through the first communication hole, and flows out of the second tip body through the second communication hole. Then, the gas flows through the third gas flow path between the outer periphery of the second tip body and the inner wall of the nozzle and is stably jetted toward the arc from the gas ejection port in the nozzle. Furthermore, as the gas flows through the first communication hole and the second communication hole, its flow rate and pressure increase due to the orifice effect. Thus, the force of the gas jetted from the gas ejection port in the nozzle can be increased.
Furthermore, it is preferable that the insulating bushing include a tubular portion to which a torch inner tube that supplies electric current to the first tip body is fitted, and an insulating tubular portion to which a bushing insertion portion formed at a base end portion of the second tip body is fitted, and that the insulating bushing be provided on the torch body.
With this configuration, because the insulating bushing provided on the torch body has the tubular portion to which the torch inner tube that supplies electric current to the first tip body is fitted, and the insulating tubular portion to which the bushing insertion portion of the second tip body is fitted, the first and second tip bodies can be provided in the torch body in such a manner that their base ends are insulated from each other.
Furthermore, it is preferable that the welding torch have a through-hole to which a ring-like insulating member formed of an insulative material is internally fitted from the outside of the nozzle, and an electric wire connected at one end to the power source and at the other end to the second tip body that is electrically connected to the welding wire via the second tip extend through the ring-like insulating member. With this configuration, because the electric wire connected to the power source and the second tip body that is electrically connected to the welding wire via the second tip extends through the ring-like insulating member internally fitted to the through-hole from the outside of the nozzle, electric current from the power source can be supplied to the welding wire from the outer periphery of the nozzle via the second tip body.
Furthermore, it is preferable that one or both of the first and second tips be connected to the power source via a variable resistor. With this configuration, because one or both of the first and second tips are connected to the power source via a variable resistor, the amount of electric current supplied from the power source to the welding wire via the first and second tips can be adjusted.
Furthermore, it is preferable that the first and second tips be supplied with electric current from different power sources. With this configuration, because the first and second tips are supplied with electric current from different power sources, the amounts of current supplied from the power sources to the first and second tips can be differentiated from each other.
Furthermore, it is preferable that the different power sources include at least one pulse power source, and, if both of the power sources are pulse power sources, pulsed electric current outputted from one power source be synchronized with the timing of pulsed electric current outputted from the other power source. With this configuration, because at least one of the power sources is a pulse power source that outputs pulsed electric current, and pulsed electric current outputted from one power source is synchronized with the timing of pulsed electric current outputted from the other power source, a stable welding current can be obtained.
Furthermore, it is preferable that the distance between the first and second tips can be adjusted by changing the lengths of the first and second tips or the lengths of the first and second tip bodies.
Furthermore, it is preferable that the axes of the first and second tips be offset from each other by 2 mm or less. With this configuration, because the axes of the first and second tips are off set from each other by 2 mm or less, the welding wire is pressed against wire insertion portions of the tips. Thus, poor contact between the tips and the welding wire can be eliminated.
Furthermore, it is preferable that the distal end portion of the second tip body provided with the second tip be removably attached to the base end portion of the second tip body. With this configuration, because the distal end portion of the second tip body provided with the second tip is removably attached to the base end portion, the distal end portion can be attached to or removed from the base end portion.
In the welding torch of the present invention, the first and second tips are axially arranged, in two stages, at a predetermined distance from each other and supply electric current to the welding wire. By providing two current supply points in the axial direction, the amount of heat generated by the tips, the amount of tip wear, and the tip-replacement frequency can be reduced, thereby improving the welding and tip-replacement efficiencies. At the same time, the size of the entire welding torch can be reduced. Furthermore, with the welding torch of the present invention, the gas supplied to the torch body flows through the first hollow portion in the first tip body, the first communication hole, the second hollow portion in the second tip body, the second communication hole, the third gas flow path, and is jetted from the gas ejection port in the nozzle. As the gas flows through the first communication hole and the second communication hole, its flow rate and pressure increase due to the orifice effect. Thus, gas can be stably jetted from the gas ejection port.
Furthermore, with the welding torch of the present invention, by insulating the base end portions of the first and second tip bodies from each other with the insulating bushing, two tips can be disposed in the torch body. Furthermore, with the welding torch of the present invention, because electric current from the power source can be supplied from the outside of the nozzle to the welding wire via the second tip body, the electric current can be easily supplied to the two tips. Furthermore, with the welding torch of the present invention, because the total electric current outputted from the welding power source is shared by the first and second tips, the amount of current flowing through one tip is reduced. Thus, the resistance of the tips, the amount of heat generated by the tips, the amount of tip wear, and the tip-replacement frequency can be reduced, thereby increasing the welding operation efficiency.
Furthermore, with the welding torch of the present invention, because the first and second tips are each connected to the power source via a variable resistor, the amount of electric current supplied to the welding wire can be flexibly controlled according to each tip. Furthermore, with the welding torch of the present invention, because electric current is supplied to the first and second tips from different power sources, the amount of electric current supplied from each power source to the corresponding tip can be reduced to a level appropriate for that tip, thereby reducing the amount of tip wear. Furthermore, with the welding torch of the present invention, because at least one of the power sources is a pulse power source, and pulsed electric current from one power source is synchronized with the timing of pulsed electric current outputted from the other power source, it is possible to supply a stable welding current and maintain a constant arc length.
Furthermore, with the welding torch of the present invention, the axial distance between the first and second tips can be appropriately adjusted by changing the lengths of the first and second tips or the lengths of the tip bodies supporting the first and second tips. Furthermore, with the welding torch of the present invention, because the axes of the first and second tips are slightly offset from each other, the welding wire is pressed against the wire insertion portions of the tips. Thus, poor contact between the tips and the welding wire can be eliminated. Furthermore, with the welding torch of the present invention, the distal end portion of the second tip body provided with the second tip is removably mounted to the base end portion. Thus, the first tip accommodated in the second tip body can be easily removed and replaced by removing the distal end portion.
A welding torch according to an embodiment of the present invention will be described in detail below with reference to the drawings. Before describing a welding torch 1 of the present invention, a welding apparatus A in which the welding torch 1 is provided, a power source 10, and a gas source G will be described with reference to
The welding apparatus A shown in
The power source 10 is, for example, a welding power source (welder) that supplies electric current to a first tip body 5 and a second tip body 7. The first tip body 5 and the second tip body 7 are connected to a positive electrode of the power source 10. A negative electrode of the power source 10 is connected to the work piece B. The gas source G is connected to the welding torch 1 via a pipe-like member 25.
As shown in
The torch body 2 includes a conductive torch inner tube 21 serving as a current supply path 21a, an insulating bushing 22 externally fitted to the torch inner tube 21, a conductive torch outer tube 23 externally fitted to the insulating bushing 22, an insulative fixing tube 24 for fixing the torch inner tube 21 to the torch outer tube 23 with the insulating bushing 22 therebetween, and the insulative pipe-like member 25 fixed to the base end portion of the torch outer tube 23.
As shown in
The wire path (not shown) is formed of a hollow-portion liner provided in the torch inner tube 21, and the welding wire W extends therethrough. The wire path also serves as the gas supply path (not shown), and a space around the welding wire W in the wire path constitutes the gas supply path. The current supply path 21a is the torch inner tube 21 composed of a conductive material. Electric current is supplied from the power source 10 to the current supply path 21a through an electric wire 11, and flows through the first tip body 5 and the first tip 4 to the welding wire W.
The insulating bushing 22 is a substantially cylindrical member formed of an insulative material, such as resin. The insulating bushing 22 serves two functions: one is an insulating member that insulates the torch inner tube 21 electrically connected to the first tip 4 and the first tip body 5 from the second tip body 7 electrically connected to the second tip 8; and the other is a cooling member for cooling the torch body 2. The insulating bushing 22 is provided inside the nozzle 3, on the outer periphery of the first tip body 5. The insulating bushing 22 includes a tubular portion 22a to which the current supply path 21a, whose distal end is exposed, is fitted, an insulating tubular portion 22b internally fitted to a bushing insertion portion 7e provided at the base end portion of the second tip body 7, and a coolant circulating path (not shown) communicating with coolant circulating pipes 26 and through which coolant circulates.
The tubular portion 22a supports the cylindrical current supply path 21a internally fitted thereto. The insulating tubular portion 22b is a cylindrical portion formed on the outer periphery of the distal end portion of the insulating bushing 22, via which the second tip body 7 is externally fitted to the insulating bushing 22.
The coolant circulating path serves as a water jacket for cooling the torch body 2 heated by welding, by allowing coolant supplied from the coolant circulating pipes 26 to flow therein. The coolant circulating path is formed inside the insulating bushing 22 and torch outer tube 23.
As shown in
As shown in
As shown in
The first tip 4, formed of a substantially cylindrical conductive member, is a contact tip that is removably attached to the distal end of the first tip body 5, supports the welding wire W inserted therethrough, and supplies electric current having passed through the first tip body 5 to the welding wire W. The first tip 4 includes a wire insertion portion 4a that supports the welding wire W inserted therethrough and supplies current thereto, and a first-tip male screw 4b via which the first tip 4 is connected to the first tip body 5.
The first tip body 5 is a conductive cylindrical member mounted, inside the nozzle 3, to the torch body 2 in an electrically conducting manner, and the welding wire W, gas, and electric current having passed through the torch body 2 is supplied to the first tip body 5. The first tip body 5 has a first gas flow path 5a through which gas flowing out of the torch body 2 flows, a first hollow portion 5b serving as the first gas flow path 5a, first communication holes 5c provided in the outer periphery of the first tip body 5 so as to communicate with the first hollow portion 5b, a first-tip-body male screw 5d onto which a torch-inner-tube female screw 21e is threaded, and a first-tip fixing screw 5e onto which the first-tip male screw 4b is threaded.
The first gas flow path 5a is a flow path through which gas supplied from the torch inner tube 21 flows toward the first communication holes 5c. The welding wire W is disposed along the axis portion of the first hollow portion 5b, and the gas flows therethrough. The first communication holes 5c having the same size are provided in the outer periphery of the first tip body 5 at equal intervals, through which the gas in the first gas flow path 5a flows into a second gas flow path 7a.
The first-tip-body male screw 5d formed on the outer periphery of the base end portion of the first tip body 5 is threaded into the torch-inner-tube female screw (not shown) of the torch inner tube 21, connecting the first tip body 5 to the distal end of the torch inner tube 21. The first-tip fixing screw 5e is a female screw formed on the inner wall of the distal end portion of the cylindrical first tip body 5, to which the first tip 4 can be removably fixed.
The second tip 8 is a contact tip that is removably supported at the distal end portion of the second tip body 7 and supplies current having passed through the second tip body 7 to the welding wire W. The welding wire W inserted through the first tip 4 passes through the second tip 8. For example, the second tip 8 is formed of a substantially cylindrical conductive member and has the same shape as the first tip 4. The second tip 8 includes a wire insertion portion 8a that supports the welding wire W inserted therethrough and supplies current thereto, and a second-tip male screw 8b via which the second tip 8 is connected to the second tip body 7. As shown in
As shown in
As shown in
The second gas flow path 7a is a flow path through which gas having entered the second tip 8 from the inside of the first tip body 5 through the first communication holes 5c flows toward the second communication holes 7c. In the second hollow portion 7b, the welding wire W is disposed along the axis portion, and the gas flowing out of the first communication holes 5c flows toward the second communication holes 7c. The second communication holes 7c having the same size are provided in the outer periphery of the distal-end-side cylindrical portion 7g at equal intervals, so that the gas in the second gas flow path 7a flows into the third gas flow path 3a.
The second-tip fixing screw 7d is a female screw formed in a hole provided in the bottom (the distal end surface) of the substantially cylindrical second tip body 7 having a bottom. By threading the second-tip fixing screw 7d onto the second-tip male screw 8b of the second tip 8, the second tip 8 is fixed to the second tip body 7 in an electrically conducting manner.
The bushing insertion portion 7e is a cylindrical portion formed on the inner wall at the base end portion of the base-end-side cylindrical portion 7f. By inserting the insulating tubular portion 22b of the insulating bushing 22 into the bushing insertion portion 7e, the second tip body 7 is externally fitted to the insulating bushing 22 of the torch body 2. The bushing insertion portion 7e and the electric-wire connecting portion 7h are formed in the base-end-side cylindrical portion 7f. The current supply path 21a of the torch inner tube 21 and the welding wire W are disposed in the base-end-side cylindrical portion 7f via the insulating bushing 22, and the large-diameter portion 3d is disposed on the outer periphery of the base-end-side cylindrical portion 7f. Furthermore, the insulating ring 6 is disposed on the base end surface.
The distal-end-side cylindrical portion 7g having the second communication holes 7c and the second-tip fixing screw 7d is disposed in the small-diameter portion 3c with a space (the third gas flow path 3a) therebetween. The second tip body 7 may be an integrated component. The distal-end-side cylindrical portion 7g may have the base-end removable screw 7i and the distal-end removable screw 7j threaded with each other, so that the distal end portion can be removably attached to the base end portion to ease replacement of the first tip 4 disposed in the second tip body 7. Electric current is supplied through the electric wire 11 from the first tip body 5 via the first tip 4 to the welding wire W, and electric current is supplied through the electric wire 12 from the second tip body 7 via the second tip 8 to the welding wire W.
The base-end removable screw 7i is, for example, a female screw formed at the base end portion of the distal-end-side cylindrical portion 7g. The distal-end removable screw 7j is, for example, a male screw formed at the distal end of the distal-end-side cylindrical portion 7g, onto which the base-end removable screw 7i is threaded. That is, the second tip body 7 is configured such that the distal end portion having the second tip 8 can be removed from the base end portion, i.e., the second tip body 7 can be divided into two parts by removing the distal end portion, enabling the first tip 4 in the second tip body 7 to be easily replaced.
As shown in
The insulating ring 6 is a ring-like member disposed between the distal end surface of the torch outer tube 23 and the base end surface of the second tip body 7 to insulate them from each other.
Next, referring to
When welding is performed, electric current is supplied through the electric wire 11 to the welding wire W, via the torch inner tube 21, the first tip body 5, and the first tip 4. Furthermore, electric current flows through the electric wire 12 from the welding wire W to the work piece B, via the second tip body 7 and the second tip 8, generating arc.
Then, as shown in
As shown in
As shown in
The distance L1 between the first tip 4 and the second tip 8 of the welding torch 1, assembled as shown in
Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it may be appropriately modified within a scope not departing from the spirit of the present invention. Note that the configurations already explained will be denoted by the same reference numerals, and the description for such configurations will be omitted.
In the embodiment described above, a configuration in which one power source 10 is used has been described, as shown in
Furthermore, the power source 10A including the first power source 10A1 and the second power source 10A2, shown in
Alternatively, the welding torch 1 may include an urging member including a spring that urges the welding wire W in a direction perpendicular to the axial direction, so that the axes 01 and 02 are offset from each other. By urging the welding wire W horizontally with the urging member, the poor contact between the welding wire W and the first tip 4 and the second tip 8 is eliminated.
Note that the first tip 4, serving as a current supply point when supplying electric current to the welding wire W, may be omitted if the electric current can be supplied to the welding wire W. For example, the first tip 4 and the first tip body 5 may be configured as a single component. In such a case, when a distal end hole in the first tip is worn away, the first tip 4 and the first tip body 5, configured as a single component, are replaced. In addition, the shape of the first tip 4 is not specifically limited as long as the current supply function is ensured. The shape of the first tip 4 may be, for example, a cylindrical shape or a polygonal cylindrical shape with a rectangular or polygonal cross section; it may be changed appropriately.
Next, referring mainly to
Table 1 shows the “welding conditions” used in the research shown in
As shown in
As shown in
In contrast, when welding was performed using the welding torch 1 of the present invention, the first tip 4 reached the amount of wear of 100% after about 4t−x hours from the start of welding, and the first tip 4 was replaced (a first tip replacement). From
When welding was performed using the welding torch 1 of the present invention, the second tip 8 reached the amount of wear of 100% after about 2t−x hours from the start of welding, and the second tip 8 was replaced (a first tip replacement). Then, after about 4t−x hours from the start of welding, a second tip replacement was performed. From
As shown in
As shown in
The current consumed when the welding wire 300 was melted at a melting speed of about 230 [g/min] using the welding torch 100 of the Comparative Example was about 500 A. In contrast, the current consumed when welding was performed using the welding torch 1 of the present invention, at the same melting speed, with the distance L1b of 15 mm, was about 445 A, which is lower than that of the Comparative Example.
The current consumed when the welding wire 300 was melted at a melting speed of about 270 [g/min] using the welding torch 100 of the Comparative Example was about 550 A. In contrast, the current consumed when welding was performed using the welding torch 1 of the present invention, at the same melting speed, with the distance L1b of 15 mm, was about 495 A, which is lower than that of the Comparative example.
The current consumed when the welding wire 300 was melted at a melting speed of about 315 [g/min] using the welding torch 100 of the Comparative Example was about 605 A. In contrast, the current consumed when welding was performed using the welding torch 1 of the present invention, at the same melting speed, with the distance L1b of 15 mm, was about 550 A, which is lower than that of the Comparative Example. From
As has been described above, the welding torch 1 of the present invention has two current supply points, namely, the first tip 4 and the second tip 8, provided in a separated manner. Thus, the amount of electric current supplied to one current supply point is smaller than the welding torch 100 of the Comparative Example. Accordingly, the heat generated by the first tip 4 and the second tip 8 can be reduced, thereby reducing the frequency of the replacement of the first tip 4 and the second tip 8. Furthermore, a problem of unwanted fusion of the welding wire W and the first tip 4 and the second tip 8, which tends to occur when an excessive amount of electric current flows through the current supply point, can be solved because the electric current flowing through each current supply point, i.e., the first tip 4 or the second tip 8, is drastically reduced. Thus, the arc can be stabilized for a long term.
Number | Date | Country | Kind |
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2011-002581 | May 2011 | JP | national |