Welding robot

Abstract

To provide a welding robot capable of performing stable welding by imparting a bending tendency according to the rigidity etc. of a welding wire with a simple structure. [Solution] A welding robot 1 includes at least a welding torch 10, a manipulator 6 that supports the welding torch, a wire feeder 4 that feeds the welding wire to the welding torch, and a conduit cable 3a that serves as a feeding path for the welding wire. The conduit cable includes at least one turning part that has a ring-shaped shape when projected from at least one direction, and the shape of the turning part is maintained by a cable auxiliary tool.

Description

[Technical field]

[0001] The present invention relates to a welding robot. [Background technology]

[0002] Conventionally, a contact tip provided on a welding torch for arc welding guides a welding wire toward a welding point and also functions as a current-carrying component that supplies power to the welding wire.

[0003] The welding wire fed to the contact tip is generally bent because it is stored in a spool or pack winding form. Due to this bend, the welding wire comes into contact with the inner surface of the contact tip, and this contact position becomes the power supply part. The contact force between the welding wire and the contact tip depends on the bend of the welding wire and varies depending on conditions such as the rigidity of the welding wire and the spool or pack winding form. When the contact force between the welding wire and the contact tip is small, if the opening of the contact tip becomes even slightly larger due to wear of the contact tip, it becomes difficult for the welding wire and the contact tip to come into contact with each other. In this case, fusion of the contact tip and the wire due to a sudden increase in the electrical resistance of the power supply part (hereinafter also referred to as tip fusion) and unstable arc due to poor current flow in the power supply part are likely to occur.

[0004] In response to this, Patent Document 1 discloses a configuration in which a pressing means is provided inside the contact tip for pressing the welding wire against the contact surface of the contact tip, and the pressing force is used to forcibly contact the welding wire with a power supply part of the contact tip. Patent Document 2 discloses a configuration in which a circumferential path for circulating the wire is provided inside a wire feeder, and a predetermined bend is imparted to the wire. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-34311 [Patent Document 2] JP 2013-193117 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, contact tips are consumables with a relatively short product life, and there is a problem that the manufacturing cost increases if the structure of the contact tip becomes complicated. Also, when a circumferential path is provided in the wire feeder, the internal structure of the wire feeder becomes complicated, and there is a problem that it is difficult to adjust the bending tendency given to the wire according to the rigidity of the wire, etc.

[0007] The present invention has been made in consideration of the above problems, and its purpose is to provide a welding robot that can perform stable welding by imparting a bending tendency to the welding wire in accordance with the rigidity, etc. of the welding wire with a simple structure. [Means for solving the problem]

[0008] The above object of the present invention is achieved by the following configuration. (1) a welding torch; A manipulator supporting the welding torch; a wire feeder that feeds a welding wire to the welding torch; A conduit cable which serves as a feeding passage for the welding wire; A welding robot comprising at least The conduit cable has at least one turning portion having a circular shape when projected from at least one direction, The pivoting part is held in shape by a cable aid. A welding robot characterized by: Effect of the Invention

[0009] According to the present invention, a welding robot capable of stable welding can be provided by imparting a bending tendency to the welding wire in accordance with the rigidity, etc. of the welding wire with a simple structure. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a welding robot according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a welding torch used in the welding robot shown in FIG. [Diagram 3] Fig. 3(a) is an enlarged view of the swivel part, and Fig. 3(b) is an enlarged view of the swivel part as viewed from the direction of arrow III in Fig. 3(a). [Figure 4] FIG. 4 shows the target test results. [Diagram 5] Fig. 5(a) is a diagram showing the relationship between the radius of curvature of the turning portion and the wire cast for wire A. Fig. 5(b) is a diagram showing the relationship between the radius of curvature of the turning portion and the wire cast for wire B. Fig. 5(c) is a diagram showing the relationship between the radius of curvature of the turning portion and the wire cast for wire C. [Figure 6] Fig. 6(a) is a diagram showing the relationship between the pitch distance of the turning part and the wire cast, and Fig. 6(b) is a diagram showing the relationship between the pitch distance of the turning part and the wire jump. [Figure 7] FIG. 7 is a schematic diagram showing a welding robot according to a modified example of this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a schematic diagram showing a welding robot according to an embodiment of the present invention. Fig. 2 is a diagram showing a welding torch used in the welding robot shown in Fig. 1. In this embodiment, an arc welding robot (hereinafter, simply referred to as a "welding robot") using a consumable electrode gas-shielded arc welding method will be described as an example.

[0012] As shown in FIG. 1, welding robot 1 includes a wire pack 2, conduit cables 3a and 3b, a wire feeder 4, a welding power source 5, a manipulator 6, a robot control device 8, and a welding torch 10.

[0013] <Wirepack> 1, the wire pack 2 is a supply source of the welding wire WR and stores a predetermined amount of the welding wire WR. For example, a copper-plated wire or a non-copper-plated wire can be used as the welding wire WR. When the welding torch 10 according to the present embodiment is used for semi-automatic welding, a spooled wire can be used.

[0014] <Conduit cable> 1, the conduit cables 3a and 3b are passages for feeding the welding wire WR. One end of the conduit cable 3a is connected to a wire feeding device 4, and the other end is connected to a welding torch 10. In addition, one end of the conduit cable 3b is connected to a wire pack 2, and the other end is connected to the wire feeding device 4. As will be described later, the conduit cable 3a according to this embodiment includes a swivel portion 30.

[0015] <Wire feeder> The wire feeder 4 pays out the welding wire WR using a roller or the like and feeds it through the conduit cables 3a, 3b to the welding torch 10. By being provided with this wire feeder 4, the welding robot 1 can automatically supply the welding wire WR to the welding torch 10.

[0016] <Welding power source> The welding power source 5 is a source of a welding current, and supplies the welding current to the welding torch 10 via the wire feeder 4 and a power cable (not shown).

[0017] <Manipulator> The manipulator 6 is a multi-joint robot that supports a welding torch 10. The manipulator 6 is operated and controlled, for example, through a robot control device 8 installed at a remote location, and can perform welding work in place of an operator.

[0018] <Robot control device> The robot control device 8 mainly controls the operation of the manipulator 6. The robot control device 8 holds teaching data that predetermines the operation pattern, welding start position, welding end position, welding conditions, weaving operation, etc. of the manipulator 6, and controls the operation of the manipulator 6 by instructing the manipulator 6 on these. The robot control device 8 also provides welding conditions such as welding current and welding voltage during welding work to the welding power source 5 in accordance with the teaching data. Note that the robot control device 8 may be connected to a controller for creating or displaying a program for operating the manipulator 6, inputting teaching data, inputting information to be instructed to the welding power source 5, etc.

[0019] <Welding torch> 2, the welding torch 10 is equipped with a torch barrel 14 attached to the manipulator 6, a contact tip 16 attached to the torch barrel 14, and a cylindrical nozzle 15 attached to the torch barrel 14 and accommodating the contact tip 16 therein, and is used for performing gas-shielded arc welding. Note that, in general, cables connected to the welding torch 10, such as a conduit cable for supplying the welding wire WR, a power cable for supplying a welding current (not shown), and a hose for supplying a shielding gas stored in a shielding gas storage means (not shown), are referred to as torch cables, but only the conduit cable is shown in FIG. 1.

[0020] FIG. 3(a) is an enlarged view of the turning portion of the conduit cable shown in FIG. 1. FIG. 3(b) is an enlarged view of the turning portion as viewed from the direction of the arrow III in FIG. 3(a). As shown in FIG. 1, FIG. 3(a), and FIG. 3(b), in this embodiment, the conduit cable 3a includes one turning portion 30. As shown in particular in FIG. 3(a) and FIG. 3(b), the turning portion 30 refers to a range from the starting point 31 to the end point 32 with respect to the extending direction of the conduit cable 3a. Here, the end point 32 is located downstream of the starting point 31 in the feeding direction of the welding wire WR. In this embodiment, the turning portion 30 is configured by bending the range from the starting point 31 to the end point 32 in the conduit cable 3a with a constant bending radius R (hereinafter, referred to as the radius of curvature R). When viewed from a direction in which the starting point 31 and the end point 32 appear to overlap (the direction of the arrow III in FIG. 3(a)), the shape of the projected turning portion 30 is annular.

[0021] Either one of the conduit cables 3a, 3b may have at least one turning portion 30, and the turning portion 30 may be provided on the conduit cable 3b connecting the wire pack 2 and the wire feeder 4. A plurality of turning portions 30 may be provided. Furthermore, the turning portion 30 may have a ring-shaped shape projected from at least one direction, and the projected shape of the turning portion 30 is not limited to a circular ring shape, and may be an elliptical ring shape, etc. In this case, the radius of curvature of the turning portion 30 does not need to be constant in the range from the starting point 31 to the ending point 32, and the radius of curvature at the portion where the radius of curvature is smallest is defined as R.

[0022] As shown in Figs. 3(a) and (b), the shape of the swivel part 30 is maintained by the cable auxiliary tool 50. The cable auxiliary tool 50 is omitted in Fig. 1 and Fig. 7 described later. The cable auxiliary tool 50 in this embodiment has two ring members 51, 51, one rod member 52, and two band members 53, 53. The ring members 51, 51 are fitted to the outer peripheral surface of the conduit cable 3a and are fixed to the start point 31 and the end point 32 of the swivel part 30, respectively. The rod member 52 and the band members 53, 53 are members for connecting the two ring members 51, 51, and holes (not shown) are provided at both ends of the rod member 52 in the longitudinal direction. The rod member 52 and the ring member 51 are fixed to each other by, for example, binding the hole of the rod member 52 and the ring member 51 with the band member 53. As a result, the relative positions of the start point 31 and the end point 32 of the swirl portion 30 are fixed, and the shape of the swirl portion 30 is maintained.

[0023] In this embodiment, the turning part 30 is formed in a spiral shape with the start point 31 and the end point 32 of the turning part 30 being separated from each other. That is, as described above, the start point 31 and the end point 32 of the turning part 30 are fixed at a certain distance by the rod member 52. The turning part 30 is bent with a predetermined radius of curvature R between the start point 31 and the end point 32, and is formed in a spiral shape with an axis O parallel to the longitudinal direction of the rod member 52 as a central axis. Here, the direction of the axis O coincides with the direction indicated by the arrow III. By forming the turning part 30 in a spiral shape, the resistance (hereinafter referred to as the feeding resistance) when the welding wire WR is fed through the conduit cable 3a is reduced. This makes it easier to stably feed the welding wire WR to the welding torch 10.

[0024] The cable auxiliary tool 50 can arbitrarily change the distance L between the start point 31 and the end point 32 of the turning part 30 (hereinafter, also referred to as the pitch distance L) and the radius of curvature R of the turning part 30. In the cable auxiliary tool 50 in this embodiment, the pitch distance L can be changed by changing the length of the rod member 52. The radius of curvature R changes depending on the length of the conduit cable 3a in the extension direction between the start point 31 and the end point 32. That is, the radius of curvature R of the turning part 30 can be changed by moving the fixing points of the ring members 51, 51 in the extension direction of the conduit cable 3a. It is also possible to set the pitch distance L of the turning part 30 to 0 mm. In this case, for example, without providing the rod member 52, the ring member 51 located at the start point 31 and the ring member 51 located at the end point 32 are fixed by directly binding them with the band member 53. In this case, the turning part 30 is not spiral but is circular and included in approximately the same plane. In this manner, by configuring the pitch distance L and the radius of curvature R in the turning portion 30 to be arbitrarily changeable, it is possible to achieve both a reduction in the feeding resistance and the imparting of an appropriate bending tendency to the welding wire WR depending on the type of the welding wire WR, etc.

[0025] As described above, in the welding robot 1 provided with the swivel unit 30, when the welding wire WR is fed to the welding torch 10 via the conduit cable 3a, the welding wire WR is given a certain bending tendency by passing through the swivel unit 30. This ensures the contact force between the welding wire WR and the contact tip 16.

[0026] In addition, in the welding robot 1 according to this embodiment, the conduit cable 3a is provided with the turning portion 30 using the cable auxiliary tool 50. This makes it possible to impart a bending tendency according to the rigidity and the like of the welding wire WR with a simple structure, and thus makes it possible to provide a welding robot 1 capable of stable welding.

[0027] The present invention is not limited to the above-mentioned embodiment. The position and number of the swivel parts 30 can be changed as desired. In addition, the cable auxiliary tool 50 can be selected in any shape or material as long as it can fix the relative positions of the start point 31 and the end point 32 of the swivel part 30. For example, the ring members 51, 51 and the rod member 52 may be integrated. In addition, the fixing points of the cable auxiliary tool 50 on the conduit cables 3a, 3b may be different from the start point 31 and the end point 32 of the swivel part 30.

[0028] [Example] Hereinafter, a test result in the case where the welding wire WR was fed using the welding robot 1 according to the embodiment will be described.

[0029] First, the target testing device will be described. When the wire feeder 4 is driven, the welding wire WR drawn out from the wire pack 2 advances through the conduit cables 3a and 3b, and is fed to the contact tip 16 of the welding torch 10.

[0030] The welding wire WR fed from the contact tip 16 was protruded from the tip of the contact tip 16, and the coordinate positions of the welding wire WR in the X and Y directions were measured at a point 150 mm from the tip of the contact tip 16, thereby testing the targeting ability of the welding wire WR. The X and Y directions are directions perpendicular to the up-down direction in FIG. 1 in which the contact tip 16 extends. The X and Y coordinate positions were measured 100 times or more, and the welding wire WR was cut at the exit of the contact tip 16 after each measurement.

[0031] In this target test, the targeting property of the welding wire WR was tested in the case where the conduit cable 3a had the turning portion 30 bent clockwise, the case where the conduit cable 3a had the turning portion 30 bent counterclockwise, and the case where the conduit cable 3a did not have the turning portion 30. Here, clockwise means that the direction from the start point 31 to the end point 32 of the turning portion 30 is clockwise when the welding torch 10 side is viewed from the wire feeder 4 side in FIG. 1. Counterclockwise means that the direction from the start point 31 to the end point 32 of the turning portion 30 is counterclockwise when the welding torch 10 side is viewed from the wire feeder 4 side in FIG. 1. In addition, in this test, the pitch distance L of the turning portion 30 is 110 mm, and the curvature radius R is 72 mm.

[0032] Fig. 4 is a diagram showing the results of the target test. As shown in Fig. 4, it was confirmed that the welding wire WR is more easily displaced in the Y direction and the X direction when the conduit cable 3a has the clockwise turning portion 30 and when the conduit cable 3a has the counterclockwise turning portion 30 than when the conduit cable 3a does not have the turning portion 30. Therefore, it is considered that the turning portion 30 can impart a certain bending tendency to the welding wire WR regardless of whether the turning portion 30 is clockwise or counterclockwise, i.e., regardless of the rotation direction.

[0033] 4, it can be seen that when the conduit cable 3a has the clockwise turning portion 30, the displacement of the welding wire WR is slightly larger than when the conduit cable 3a has the counterclockwise turning portion 30. That is, in this test result, the clockwise turning portion 30 is considered to be slightly superior to the counterclockwise turning portion 30 in that it is easier to ensure the contact force between the welding wire WR and the contact tip 16. The rotation direction of the turning portion 30 can be appropriately selected depending on the rotation direction of the welding wire WR stored in the wire pack 2, the type of welding wire WR, etc.

[0034] Next, the relationship between the radius of curvature R and pitch distance L of the turning portion 30 and the bending tendency will be described. FIG. 5 is a diagram showing the relationship between the radius of curvature of the turning portion and the wire cast for each type of welding wire (Wire A, Wire B, Wire C). FIG. 5(a) is a diagram showing the relationship between the radius of curvature of the turning portion and the wire cast for Wire A. FIG. 5(b) is a diagram showing the relationship between the radius of curvature of the turning portion and the wire cast for Wire B. FIG. 5(c) is a diagram showing the relationship between the radius of curvature of the turning portion and the wire cast for Wire C. Note that Wires A and B are general-purpose welding wires, and are different in type according to the JIS standard. Specifically, Wire A is a type of wire specified as YGW11 in JIS Z 3312:2009, and Wire B is a type of wire specified as YGW18. Wire C is the same type as Wire A in the JIS standard, but has higher rigidity than Wire A. When investigating the relationship between the radius of curvature R of the turning portion 30 and the wire cast, a conduit cable of the same length is used, and therefore the pitch distance L of the turning portion 30 is set to a distance at which the conduit cable fits into a natural shape for each radius of curvature R. In this embodiment, the pitch distance L of the turning portion 30 is set to 14 mm to 345 mm. The wire cast refers to the radius of a circle formed by the welding wire WR when the welding wire WR having a certain bend is placed on a horizontal surface, and indicates the degree of the bend.

[0035] As shown in Figs. 5(a) and 5(b), in the case of Wire A and Wire B, when the radius of curvature R of the turn portion 30 is 150 mm, the wire cast reaches a plateau at about 1000 mm. Normally, in the case of Wire A and Wire B, when the conduit cable 3a is not provided with the turn portion 30 and a bend is not imparted, the wire cast is about 1000 mm. That is, by providing the conduit cable 3a with the turn portion 30 and setting the radius of curvature R to 150 mm or less, the wire cast can be suppressed to less than 1000 mm, and it is considered that the bend can be imparted to Wire A and Wire B. Also, according to Fig. 5(c), in the case of Wire C, when the radius of curvature R is 150 mm or less, the wire cast is smaller than when the conduit cable 3a is not provided with the turn portion 30. Therefore, it is considered effective to set the radius of curvature R of the turn portion 30 to 150 mm or less in the case of Wire C.

[0036] Here, from the viewpoint of suppressing the feeding resistance of the welding wire WR, the wire cast is preferably 350 mm or more. For example, if the wire cast is smaller than 350 mm, the feeding resistance becomes large, and there is a risk of tip fusion or arc instability occurring. From the above, in order to impart a bending tendency to the welding wire WR while suppressing the feeding resistance, the curvature radius R of the turning portion 30 is preferably 50 mm or more and 150 mm or less.

[0037] In order to ensure a more stable contact force between the welding wire WR and the contact tip 16, the wire cast is preferably 650 mm or less. For example, if the wire cast is greater than 650 mm, poor electrical conduction may occur, and tip fusion or arc instability may occur. That is, the radius of curvature R of the swirl portion 30 is more preferably 50 mm or more and 75 mm or less, and even more preferably 50 mm or more and 65 mm or less.

[0038] Fig. 6(a) is a diagram showing the relationship between the pitch distance of the turning part and the wire cast. In examining the relationship between the pitch distance L of the turning part 30 and the wire cast, the radius of curvature R of the turning part 30 was set to 75 mm. As shown in Fig. 6(a), when the pitch distance L of the turning part 30 is 170 mm or less, the wire cast is 650 mm or less, which confirms that an appropriate bend can be imparted to the welding wire WR.

[0039] FIG. 6(b) is a diagram showing the relationship between the pitch distance of the turning part and the wire jump. Here, the wire jump refers to the height to which the end of the welding wire WR jumps up vertically when the welding wire WR is placed on a horizontal surface. Note that the vertical upward direction here refers to the direction opposite to the direction of gravity. The wire jump is also an index representing the magnitude of the twist of the welding wire WR. Therefore, the smaller the wire jump, the more stable the contact position between the welding wire WR and the contact tip 16 becomes, and stable power supply can be performed. As shown in FIG. 6(b), in terms of suppressing the wire jump of the welding wire WR, the pitch distance L of the turning part 30 is preferably 40 mm or more and 170 mm or less. Moreover, it is more preferable that the pitch distance L of the turning part 30 is 40 mm or more and 120 mm or less.

[0040] Fig. 7 is a schematic diagram showing a welding robot according to a modified example of this embodiment. The welding robot 1 according to the above-mentioned embodiment is a so-called two-wire type, which includes a conduit cable 3a for supplying only the welding wire WR to the welding torch 10 and another torch cable (not shown) for supplying the welding current and the like. On the other hand, as in the modified example shown in Fig. 7, a single-wire torch cable 3c in which the supply paths of the welding wire WR, the welding current, and the shielding gas are bundled may be used. In this case, the swivel unit 30 is provided on a conduit cable 3d dedicated to the welding wire WR, which is located between the wire feeder 4 and a joint 9 where the supply paths of the welding wire WR, the welding current, and the shielding gas join.

[0041] As described above, the present specification discloses the following: (1) a welding torch; A manipulator supporting the welding torch; a wire feeder that feeds a welding wire to the welding torch; A conduit cable which serves as a feeding passage for the welding wire; A welding robot comprising at least The conduit cable has at least one turning portion having a circular shape when projected from at least one direction, The pivoting part is held in shape by a cable aid. A welding robot characterized by: According to this configuration, with a simple structure, it is possible to impart a certain bend to the welding wire and stabilize the contact between the welding wire and the contact tip inside the welding torch, thereby enabling stable welding.

[0042] (2) The cable auxiliary tool is capable of arbitrarily changing the distance between the start point and the end point of the turning portion and the radius of curvature of the turning portion. A welding robot as described in (1). According to this configuration, it is possible to impart an appropriate bend to the wire depending on the type of wire, etc., while reducing the feeding resistance of the welding wire.

[0043] (3) The swirling portion is formed in a spiral shape with a start point and an end point of the swirling portion separated from each other. A welding robot according to (1) or (2). According to this configuration, the feeding resistance of the welding wire can be reduced.

[0044] (4) The radius of curvature of the turning portion is 50 mm or more and 150 mm or less. A welding robot according to any one of (1) to (3). According to this configuration, it is possible to impart an appropriate bend to the welding wire, and the contact between the welding wire and the contact tip is stabilized.

[0045] (5) The distance between the start point and the end point of the turning part is not less than 40 mm and not more than 170 mm. A welding robot according to any one of (1) to (4). According to this configuration, it is possible to impart an appropriate bend to the welding wire, and the contact between the welding wire and the contact tip is stabilized. [Explanation of symbols]

[0046] 1. Welding robot 2 Wire Pack 3a, 3b, 3d Conduit Cable 3c Torch Cable 4 Wire feeder 5 Welding power source 6 Manipulator 8 Robot control device 9. Joint 10. Welding Torch 14 Torch Barrel 15 Nozzles 16 Contact Tip 30 Swivel section 31 Starting Point 32 End Point 50 Cable Aid 51 Ring member 52 Bar member 53 Band parts

Claims

1. A welding torch, A manipulator supporting the welding torch; a wire feeder that feeds a welding wire to the welding torch; A conduit cable which serves as a feeding passage for the welding wire; A welding robot comprising at least The conduit cable includes at least one turning portion having a circular shape when projected from at least one direction, The pivoting part is held in shape by a cable aid. A welding robot characterized by:

2. The cable assisting tool is capable of arbitrarily changing the distance between the start point and the end point of the turning portion and the radius of curvature of the turning portion.

2. The welding robot according to claim 1 .

3. The turning portion is formed in a spiral shape with a start point and an end point of the turning portion being spaced apart.

3. The welding robot according to claim 2 .

4. The radius of curvature of the turning portion is 50 mm or more and 150 mm or less.

4. The welding robot according to claim 3 .

5. The distance between the start point and the end point of the turning portion is 40 mm or more and 170 mm or less.

5. The welding robot according to claim 3 or 4.

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