Wire buffer device, buffer amount control system, and welding system

Abstract

This wire buffer device for controlling the slackening amount of a welding wire between feeders comprises: a wire inlet; a wire outlet; a tube having a curvedly formed annular part; a rod; a slider that slides in the radial direction of the annular part; a crankshaft disposed at the center position of the annular part; and a detection sensor. The rod is connected to a sliding mechanism that slides in the radial direction of the annular part and to the crankshaft. The sliding mechanism has a tube insertion part into which the tube is inserted. The sliding mechanism slides in the radial direction of the annular part in association with the movement of the tube in the radial direction.

Description

Wire buffer device, buffer amount control system and welding system

[0001] The present invention relates to a wire buffer device, a buffer amount control system, and a welding system.

[0002]

[0003] In a conventional welding apparatus using welding wire, a buffer device is provided between a push feeder arranged on the wire pack side and feeding only in the forward direction, and a pull feeder arranged on the welding torch side and feeding in both the forward and reverse directions, for smooth supply of the welding wire. In such a welding apparatus, if the push feeder and the pull feeder have different feeding directions, a large load may be applied to the welding wire in the feeding path if a feeding error occurs, resulting in inappropriate feeding control. For this reason, a welding system has been disclosed that feeds back the load amount on the welding wire, detected by the buffer device, to the push feeder or the pull feeder.

[0003] Patent Document 1 describes a wire accommodation device that includes a housing including an entrance portion through which the wire is inserted, an exit portion, a housing area that accommodates the wire in a curved annular state, and a guide portion accommodated in the housing area, wherein one of a first end portion near the entrance portion and a second end portion near the exit portion is fixed to the housing, and the other is supported so as to be slidable along the axial direction. Similarly, Patent Document 2 describes a wire buffer forming mechanism that includes a tubular wire guide having a wire introduction end and a wire delivery end, and a support base that supports the wire guide, wherein the wire introduction end is fixed to the support base and the wire delivery end is supported so as to be axially movable relative to the support base, and the wire guide forms a loop so that the wire introduction end and the wire delivery end face in opposite directions.

[0004] Patent Document 3 describes a wire buffer forming device having a housing through which a wire passes forming an L-shaped arch between an inlet and an outlet. Patent Document 4 describes a wire accommodation device in which a wire is accommodated in an S-shaped curved state in a housing through which the wire is inserted.

[0005] Japanese Patent Publication No. 2017-217689 Japanese Patent Publication No. 2010-52021 Japanese Patent Publication No. 2017-136613 Japanese Patent Publication No. 2015-199091

[0006] The disclosures in Patent Documents 1 and 2 aim to ensure a sufficient wire capacity (hereinafter also referred to as buffer capacity or slack capacity) of the wire buffer device by forming a circular wire feed path. However, since the circularly curved wire must be accommodated in the guide section and either the inlet or outlet section must be moved significantly to absorb the wire load, the overall device becomes large. Furthermore, differences in wire diameter and hardness have a significant impact, and depending on the type of wire, the overall device may become even larger.

[0007] The disclosures in Patent Documents 3 and 4 aim to make the overall size of the device compact, but because the wires are held by bending them into an L-shape or an S-shape, there are problems in that the buffer volume cannot be sufficiently secured and the detection accuracy of the buffer volume tends to be low.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wire buffer device, a buffer amount control system, and a welding system that are compact in configuration and can accurately detect the buffer amount while ensuring a sufficient buffer amount.

[0009] The above object of the present invention can be achieved by the following configuration. (1) A wire buffer device disposed between a first feeder and a second feeder for controlling a slack amount of a welding wire between the feeders, the wire buffer device comprising: a wire inlet portion through which the welding wire is fed from the first feeder; a wire outlet portion through which the welding wire is fed toward the second feeder; a tube having a curved annular portion formed by crossing between the wire inlet portion and the wire outlet portion and through which the welding wire is inserted; a base provided with a storage area for storing the wire inlet portion, the wire outlet portion, and the annular portion of the tube; a sliding mechanism disposed in the storage area, the sliding mechanism including: a tube insertion portion through which the tube is inserted and which moves radially as the diameter of the annular portion expands or contracts; and a slider which moves together with the tube insertion portion; a crank mechanism including: a crankshaft journaled at a center position of the storage area; and a rod whose longitudinal ends are connected to the slider and the crankshaft, respectively, and which rotates the crankshaft as the slider moves. (2) A wire buffer device comprising: a detection sensor that detects a rotation angle of the crankshaft. (2) A buffer amount control system comprising: the wire buffer device described in (1), a push feeder that is the first feeder that feeds the welding wire to the wire buffer device, a pull feeder that is the second feeder to which the welding wire is fed from the wire buffer device, and a control unit. (3) A welding system comprising: a welding robot equipped with the wire buffer device described in (1), and a welding power source.

[0010] According to the present invention, it is possible to accurately detect the buffer amount while ensuring a sufficient buffer amount with a compact configuration.

[0011] FIG. 1 is a schematic diagram of a welding system in which a wire buffer device according to an embodiment is used. FIG. 2 is a schematic side view of a welding robot in which a wire buffer device according to the present embodiment is used. FIG. 3 is a perspective view of the wire buffer device. FIG. 4 is a front view of the wire buffer device. FIG. 5 is a cross-sectional view taken along line A-A in FIG. 4. FIG. 6 is a cross-sectional view of a main part of a sliding section. FIG. 7 is a front view showing the wire buffer device in an expanded state, and FIG. 8 is a front view showing the wire buffer device in a contracted state. FIG. 9 is a block diagram of a control section. FIG. 10 is a cross-sectional view of a main part of a sliding section of a second embodiment.

[0012] The configuration of a wire buffer device to which the present invention is applied will be described below with reference to the accompanying drawings. Note that each drawing is created for the purpose of explaining the present invention, and the embodiment of the present invention is not limited to the contents of the drawings.

[0013] First, in order to grasp the overall picture of a wire buffer device to which the present invention is applied, a welding system in which the wire buffer device is used will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram of a welding system in which a wire buffer device according to an embodiment is used, and Figure 2 is a schematic side view of a welding robot in which the wire buffer device according to this embodiment is used.

[0014] (Welding System) Welding system 100 includes welding robot 110, robot control device 120, welding power source 130, servo amplifier 140, pull feeder 150, push feeder 160, and wire buffer device 10. This configuration can be seen in FIG.

[0015] The welding robot 110 is equipped with a welding torch 111 as an end effector. The welding torch 111 has a current-carrying mechanism, i.e., a welding tip, that applies current to the welding wire W. When current is applied from the welding tip, the welding wire W generates an arc from its tip, and the generated heat welds the workpiece 200, which is the welding target. The welding tip is also generally referred to as a contact tip.

[0016] The welding torch 111 includes a nozzle that serves as a mechanism for ejecting a shielding gas. The shielding gas is not particularly limited, but preferably contains at least one gas with a high potential gradient among carbon dioxide, nitrogen, hydrogen, and oxygen. From the viewpoint of versatility, a gas mixture with argon gas preferably contains at least 10% by volume of carbon dioxide, more preferably 90% by volume or more of carbon dioxide, and even more preferably carbon dioxide alone. The shielding gas is supplied from a shielding gas supply device (not shown).

[0017] Robot controller 120 mainly controls the operation of welding robot 110. Robot controller 120 has control information such as the operation pattern, welding start position, welding end position, welding conditions, weaving operation, etc. of welding robot 110 input in advance using a teaching pendant (not shown) or the like. Welding robot 110 and welding power source 130 operate based on the control information input to robot controller 120. Note that robot controller 120 may be configured to be integrated with welding power source 130.

[0018] Welding power source 130 is connected to welding robot 110 via a positive power cable (not shown) so as to be able to energize a welding wire, which is a consumable electrode, and is also connected to workpiece 200 via a power cable (not shown). Workpiece 200 is also referred to as a base material.

[0019] The push feeder 160 is connected to the welding power source 130 via a signal line. In this embodiment, the push feeder 160 has a push motor (not shown) that is controlled by a feed control unit 131 provided in the welding power source 130. The feed control unit 131 is configured to include, for example, a CPU, a GPU, or a GPGPU, and their peripheral circuits, and a storage unit including a RAM as a volatile storage area and a ROM or HDD as a non-volatile storage area.

[0020] The pull feeder 150 is provided near the welding torch 111 and is connected to the servo amplifier 140. The pull feeder 150 has a servo motor (not shown) that is controlled by the feed control unit 131 via the servo amplifier 140. In this embodiment, the welding torch 111 is configured independent of the pull feeder 150, but the pull feeder 150 may be configured to be integrated into the welding torch 111.

[0021] The wire buffer device 10 is disposed between the pull feeder 150 and the push feeder 160. In this embodiment, the wire buffer device 10 is attached and fixed to the welding robot 110. Because the push feeder 160 feeds the wire only in the forward rotation direction and the pull feeder 150 feeds the wire in both the forward and reverse rotation directions, the push feeder 160 and the pull feeder 150 may have different feeding directions. Therefore, the wire buffer device 10 slackens the welding wire W and detects the amount of slack in the welding wire W and provides feedback to the pull feeder 150 or the push feeder 160, thereby enabling appropriate feeding control even in such feeding situations. Hereinafter, the amount of slack in the welding wire W that the wire buffer device 10 can absorb is also referred to as the buffer amount. That is, the feed control unit 131 can perform feed control to control the pull feeder 150 and the push feeder 160 based on the buffer amount of the welding wire W detected by the wire buffer device 10.

[0022] (Wire Buffer Device) Next, a specific configuration of the wire buffer device 10 according to this embodiment will be described with reference to Figures 3 to 6. Figure 3 is a perspective view of the wire buffer device, Figure 4 is a front view of the wire buffer device, Figure 5 is a cross-sectional view taken along line A-A in Figure 4, and Figure 6 is a cross-sectional view of a main part of the sliding portion.

[0023] The wire buffer device 10 includes a base 21 constituting an accommodation section 20, a wire inlet section 22, a wire outlet section 23, a guide section 24, a wire tube 25, a protective sleeve 26, a sliding section 30, a crank section 41, and a detection sensor 44. The base 21 forms the accommodation section 20 in which the wire tube 25, through which the welding wire W is inserted, is accommodated. The wire tube 25 accommodated in the accommodation section 20 has one end supported by the wire inlet section 22 and the other end supported by the wire outlet section 23, and has an annular section 25a that is curved into a circular shape. The sliding section 30 is attached to the annular section 25a of the wire tube 25 and moves along the radial direction of the annular section 25a.

[0024] The base 21 has a disk-shaped substrate portion 21a and an annular edge portion 21b formed upright along the outer edge side of the substrate portion 21a. This allows the base 21 to form a housing portion 20 that houses an annularly curved wire tube 25. The housing portion 20 has a housing region 20b that houses the wire tube 25 while guiding it so that it curves annularly, an introduction region 20a that guides the wire tube 25 from a wire inlet portion 22 provided at one end of the upper portion of the housing portion 20 to the housing region 20b, and an outlet region 20c that guides the wire tube 25 from the housing region 20b to a wire outlet portion 23 provided at the other end of the upper portion of the housing portion 20.

[0025] Recesses 27 in which sliding portions 30 are disposed are formed on the outer edge side of the accommodation region 20b of the accommodation unit 20. In the present embodiment, three recesses 27 and three sliding portions 30 are disposed along the outer edge of the substrate portion 21a. Specifically, a first recess 27A in which the first sliding portion 30A is disposed, a second recess 27B in which the second sliding portion 30B is disposed, and a third recess 27C in which the third sliding portion 30C is disposed are provided at equal intervals on the outer edge of the accommodation region 20b.

[0026] A guide portion 24 that guides the annular portion 25a of the wire tube 25 is formed on the outer edge side of the accommodation region 20b of the accommodation portion 20. The guide portion 24 is disposed along the inside of the edge portion 21b, is provided in an arc shape concentric with the edge portion 21b, and is a protruding piece that protrudes from the base portion 21a in the same direction as the edge portion 21b. As a result, a tube support portion that supports the wire tube 25 is formed between the guide portion 24 and the edge portion 21b.

[0027] Lids 28 that operate to open and close the storage section 20 via hinges are provided at the upper ends of the introduction area 20a and the delivery area 20c of the storage section 20. This configuration can be seen in FIG. 5. Correspondingly, a pair of fixing magnets 29, 29 that easily fix the closed lid 28 are provided in the storage section 20b. Note that an auxiliary switch 15 for performing a micro-feed operation of the welding wire W by the push feeder 160 is disposed inside the guide section 24 in the storage section 20b. This configuration can be seen in FIGS. 3 and 4.

[0028] The wire inlet portion 22 is disposed at one axial end of the upper end of the housing portion 20. One end of the wire tube 25 is attached and fixed to the wire inlet portion 22 so as not to slide in the axial direction. The wire outlet portion 23 is disposed at the other axial end of the upper end of the housing portion 20. The other end of the wire tube 25 is supported by the wire outlet portion 23 in a state where it is allowed to slide in the axial direction. The wire inlet portion 22 and the wire outlet portion 23 are disposed on approximately the same axis. This configuration can be seen in Figures 3 and 4.

[0029] The wire tube 25 is a tube through which the welding wire W is inserted and is accommodated in the accommodation section 20. Both ends of the wire tube 25 are supported by the wire inlet section 22 and the wire outlet section 23, and intersect between the introduction region 20a and the delivery region 20c. As a result, the wire tube 25 forms an annular portion 25a that curves annularly along the guide section 24 within the accommodation region 20b of the accommodation section 20. For this configuration, refer to FIGS. 3 and 4. The end of the wire tube 25 on the wire outlet section 23 side slides in the axial direction, causing the diameter of the annular portion 25a of the wire tube 25 to vary. The diameter of this annular portion 25a is also referred to as the loop diameter. As a result, the wire buffer device 10 functions as a buffer that absorbs slack in the welding wire W. For this configuration, refer to FIGS. 7 and 8.

[0030] The protective sleeves 26 are multiple cylindrical members curved in an arc so as to be disposed between the edge portion 21 b and the guide portion 24, and the wire tube 25 is inserted through the protective sleeves 26. The protective sleeves 26 are disposed intermittently so as to avoid the sliding portion 30. Specifically, the protective sleeves 26 include a first protective sleeve 26A extending from the vicinity of the wire exit portion 23 to the first sliding portion 30A, a second protective sleeve 26B extending from the first sliding portion 30A to the second sliding portion 30B, a third protective sleeve 26C extending from the second sliding portion 30B to the third sliding portion 30C, a fourth protective sleeve 26D extending from the third sliding portion 30C to the vicinity of the wire entrance portion 22, and a fifth protective sleeve 26E covering the area within the accommodating portion 20 from the portion where the annular wire tubes 25 intersect to the wire exit portion 23. The inner diameter of the protection sleeve 26 is larger than the outer diameter of the wire tube 25, and defines the range within which the diameter of the annular portion 25a of the wire tube 25 can expand and contract.

[0031] According to this configuration, the wire tube 25, whose loop diameter varies, is in sliding contact with the inner peripheral surface of the protective sleeve 26, which has little sliding resistance. This prevents the wire tube 25 from directly rubbing against the edge portion 21 b or the guide portion 24, which would otherwise cause early deterioration.

[0032] Furthermore, the fifth protective sleeve 26E provided at the wire outlet portion 23 can protect the welding wire W that becomes exposed from the wire tube 25 in the feed-out region 20c as the loop diameter of the wire tube 25 increases. Specifically, because one end of the wire tube 25 slides axially at the wire outlet portion 23, when loosened welding wire W is absorbed into the wire buffer device 10 from the wire outlet portion 23 during welding operation, the end of the wire tube 25 may be pushed into the housing portion 20, causing the welding wire W to become exposed within the housing portion 20. The fifth protective sleeve 26E can protect the welding wire W from being exposed in this way.

[0033] The sliding portion 30 and the crank portion 41 will be described with reference to Figures 5 and 6. The sliding portion 30 is provided in each of a plurality of recesses 27 arranged at equal intervals along the outer edge of the base portion 21a. In this embodiment, the sliding portion 30 includes a first sliding portion 30A arranged in the first recess 27A, a second sliding portion 30B arranged in the second recess 27B, and a third sliding portion 30C arranged in the third recess 27C. This configuration can be seen in Figures 3 and 4. Each sliding portion 30 includes a slider 31, a guide shaft 32, a support plate 33, a tube insertion portion 34, and a guide groove 35. The crank portion 41 includes a crank shaft 42 and a rod 43. The crank shaft 42 is a support member pivotally supported at the center of the accommodation area 20b. The rod 43 has both longitudinal ends connected to the slider 31 and the crankshaft 42, respectively, and rotates the crankshaft 42 in accordance with the movement of the slider 31 provided on each sliding portion 30.

[0034] The guide shafts 32 are rod-shaped members extending radially of the annular portion 25a of the wire tube 25, and are provided so as to bridge the open ends of the recesses 27. The axial ends of each guide shaft 32 are fixed to the recesses 27 by fixing bolts fastened along the axial direction of the guide shafts 32. This configuration can be seen in FIGS. 5 and 6.

[0035] The slider 31 is provided so as to slide in the radial direction of the annular portion 25a along the guide shaft 32. The slider 31 has a slider body 31a to which one end of the rod 43 and the support plate 33 are attached, and a guide tube 31b fixed to the slider body 31a and fitted onto the guide shaft 32. In other words, the one end of the rod 43 and the support plate 33 slide along the guide shaft 32 together with the slider 31.

[0036] The tube insertion portion 34 is formed between a ball bearing 36 journaled on a first support shaft 38 fixed to the support plate 33 and a roller 37 journaled on a second support shaft 39 fixed to the support plate 33. The tube insertion portion 34 configures a roller mechanism in which the wire tube 25 is inserted slidably in its longitudinal direction by arranging the ball bearing 36 and the roller 37 side by side along the extension direction of the guide shaft 32. At this time, the outer ring of the ball bearing 36 is formed with an abutment surface 36a recessed in a semicircular shape that conforms to the cross-sectional shape of the wire tube 25. As a result, the abutment surface 36a of the tube insertion portion 34 fits tightly into half of the outer peripheral surface of the cylindrical wire tube 25. This configuration can be seen in FIG. 6 .

[0037] A guide roller 40 is journaled on one end of the first support shaft 38 that constitutes the tube insertion portion 34. The guide roller 40 is disposed in a guide groove 35 formed in the recess 27 and rolls along the guide groove 35. The guide groove 35 is formed along the extending direction of the guide shaft 32. Therefore, the tube insertion portion 34 moves along the guide groove 35 that is formed along the surface direction of the substrate portion 21a. This configuration can be seen in FIGS. 5 to 7 . That is, the above-described sliding portion 30 allows the wire tube 25 inserted into the tube insertion portion 34 to slide in the axial direction by the roller mechanism, and can smoothly and accurately slide the slider 31 along the guide shaft 32 even when an external force is applied in a direction intersecting the sliding direction of the slider 31. Note that the guide roller 40 may be replaced with a pin, as described below.

[0038] The rod 43 is a member having one end attached and fixed to the crankshaft 42 and the other end attached and fixed to the slider 31, and connects the crankshaft 42 and the sliding portion 30. The rod 43 is provided in each sliding portion 30. That is, in this embodiment, the slider 31 of the first sliding portion 30A and the crankshaft 42 are connected by a first rod 43A, the slider 31 of the second sliding portion 30B and the crankshaft 42 are connected by a second rod 43B, and the slider 31 of the third sliding portion 30C and the crankshaft 42 are connected by a third rod 43C.

[0039] The crankshaft 42 is a support member journaled at the center of the housing area 20b and rotates in response to the movement of the sliders 31 provided on each sliding portion 30. The crankshaft 42 has a shaft portion 42a and a disk-shaped flange portion 42b extending radially from the shaft portion 42a. The shaft portion 42a is a cylindrical shaft member located toward the center of the housing area 20 and rotates integrally with the inner ring of a bearing 49 fixed in a through hole formed in the base plate portion 21a. The shaft portion 42a is attached to the flange portion 42b using a fixing bolt 48 provided on the same axis so that the flange portion 42b rotates integrally with the shaft portion 42a. This configuration can be seen in FIG. 5 . A first connecting portion 46A to which a first rod 43A is connected, a second connecting portion 46B to which a second rod 43B is connected, and a third connecting portion 46C to which a third rod 43C is connected are provided at equal intervals along the outer edge of the flange portion 42b. In this case, the positions of the connecting portions 46A, 46B, and 46C of the flange portion 42b are such that, in a front view, the rods 43 are inclined at the same angle about the sliding portions 30A, 30B, and 30C as axes from a line connecting the sliding portions 30A, 30B, and 30C connected to the other side of the rod 43 and the shaft portion 42a of the crankshaft 42. This configuration can be seen in Figures 7 and 8. In this embodiment, the rods 43 are inclined counterclockwise about the sliding portions 30A, 30B, and 30C as axes, but the inclination direction may be reversed.

[0040] As described above, the three sliding portions 30A, 30B, and 30C provided at equal intervals along the outer edge of the accommodation area 20b are connected via the crank portion 41 that functions as a linking mechanism. Therefore, the operations of the sliding portions 30A, 30B, and 30C are all synchronized in accordance with changes in the diameter of the annular portion 25a of the wire tube 25. This allows the loop diameter of the wire tube 25 to be smoothly enlarged or reduced while maintaining a nearly perfect circular shape without destroying or distorting the shape of the annular portion 25a, and prevents local changes in the curvature of the welding wire W within the wire buffer device 10, thereby enabling the wire buffer device 10 to be configured compactly.

[0041] Furthermore, because the connecting portions 46A, 46B, 46C that connect the crankshaft 42 and the rod 43 are arranged at equal intervals along the outer edge of the crankshaft 42, when the wire buffer device 10 is subjected to inertia, the inertias that the sliding portions 30A, 30B, 30C receive cancel each other out, and the resultant force becomes 0. In other words, even if the wire buffer device 10 mounted on the welding robot 110 is subjected to inertia during welding operation, the crankshaft 42 will not rotate on its own due to the influence of the inertia.

[0042] The detection sensor 44 is a potentiometer that is fixed to a sensor support plate 45 and is arranged coaxially with the shaft portion 42a of the crankshaft 42, and detects the rotational position of the crankshaft 42. The sensor support plate 45 is fixed to the base plate 21a via a plurality of fixing bolts 47 so as to sandwich the crankshaft 42 in the axial direction of the shaft portion 42a. In this embodiment, the sensor support plate 45 is formed in a triangular shape and is fixed to the base plate 21a by three fixing bolts 47, 47, 47 provided along the outer edge. This configuration can be seen in FIGS. 3 to 5.

[0043] (Operations and Effects) The operations and effects of the wire buffer device 10 will be described with reference to Figures 7 and 8. Figure 7 is a front view showing the wire buffer device in an expanded state, and Figure 8 is a front view showing the wire buffer device in a contracted state.

[0044] When the welding wire W becomes loose during welding, the wire buffer device 10 absorbs the looseness of the welding wire W, thereby increasing the loop diameter of the wire tube 25 in the housing portion 20. Accordingly, the crankshaft 42 rotates clockwise in a front view via the sliders 31 of the sliding portions 30A, 30B, and 30C and the rods 43A, 43B, and 43C. This causes the wire tube 25 to enter an expanded diameter state in which the loop diameter increases while maintaining the shape of the annular portion 25a. This increases the amount of welding wire W that can be accommodated in the housing portion 20. In other words, the amount of welding wire W buffered in the housing portion 20 increases. This configuration can be seen in FIG. 7 .

[0045] On the other hand, in the wire buffer device 10, when the slack in the welding wire W is eliminated, the loop diameter of the wire tube 25 in the storage portion 20 decreases. Accordingly, the crankshaft 42 rotates counterclockwise in a front view via the sliders 31 of the sliding portions 30A, 30B, and 30C and the rods 43A, 43B, and 43C. This causes the wire tube 25 to enter a reduced diameter state in which the loop diameter decreases while maintaining the shape of the annular portion 25a. This again enables the wire tube 25 to absorb the slack in the welding wire W in the storage portion 20. This configuration can be seen in FIG. 8 .

[0046] That is, the wire buffer device 10 has a compact configuration that can be accommodated within the accommodation section 20 and functions as a buffer that absorbs slack in the welding wire W during welding operation by a wire length equal to 2π times the maximum stroke amount of the slider 31 by expanding and contracting the loop diameter of the wire tube 25. Also, the wire buffer device 10 can constantly detect the buffer amount of welding wire W that can be absorbed by the accommodation section 20 by detecting the rotational position of the crankshaft 42 with the detection sensor 44. By minimizing the offset distance from the axial center of the crankshaft 42 to the connecting portion 46 and setting the angle between the line connecting the axial center of the crankshaft 42 and the connecting portion 46 and the axis of the rod 43 to about 90°, the rotation angle of the detection sensor 44 can be changed significantly relative to the displacement of the slider 31 in the loop radial direction, thereby achieving excellent detection accuracy.

[0047] (Feeding Control Unit) Next, the feeding control unit will be described with reference to Fig. 9. Fig. 9 is a block diagram of the control unit. The input side of the feeding control unit 131 is connected to the welding power source 130, the auxiliary switch 15, and the detection sensor 44. The output side of the feeding control unit 131 is connected to the push feeder 160 and the pull feeder 150.

[0048] The feed control unit 131 is configured to be able to execute feed control in which the servo motor on the pull feeder 150 side and / or the push motor of the push feeder 160 is controlled to adjust the feed rate of the welding wire W based on the buffer amount of the wire buffer device 10 detected by the detection sensor 44, thereby avoiding compression or tension of the welding wire W due to an accumulation of feed rate errors between the push feeder 160 and the pull feeder 150, and feedback-controlling the buffer amount of the wire buffer device 10 so that the appropriate position (specifically, near the middle of the stroke of the slider 31) is targeted. The feed control allows the welding wire W to be maintained in a buffered state with some slack in the wire buffer device 10 during welding operations. That is, even if the feed rate of the push feeder 160 differs from the feed direction or feed rate of the pull feeder 150, it is possible to prevent an excessive load from being applied to the welding wire W, and maintain smooth and stable feed of the welding wire W toward the welding torch 111.

[0049] Specifically, even if the forward feeding by the push feeder 160 and the reverse feeding by the pull feeder 150 overlap and the welding wire W is compressed between the push feeder 160 and the pull feeder 150, the buffer of the wire buffer device 10 can prevent the welding wire W from being buckled due to an excessive load being applied to the welding wire W. Similarly, even if the amount of welding wire W fed by the pull feeder 150 increases, the buffer of the wire buffer device 10 can prevent the welding wire W from being excessively pulled and being subjected to a load.

[0050] Furthermore, the feed control unit 131 is configured to be able to execute an assembly auxiliary control for driving the push motor of the push feeder 160 in the forward direction when a pressing operation of the auxiliary switch 15 in the wire buffer device 10 is detected. According to the assembly auxiliary control, the welding wire W can be fed out simply by pressing the auxiliary switch 15. Therefore, when performing the assembly work of inserting the welding wire W into the wire tube 25, the welding wire W can be fed from the push feeder 160 to the torch tip without getting caught anywhere in the feeding path, making the assembly work of the wire buffer device 10 easier.

[0051] The feed control unit 131 may be configured to drive the push motor while the auxiliary switch 15 is being pressed, or may be configured to feed the welding wire W only by a preset small feed width when the pressing of the auxiliary switch 15 is detected. The auxiliary switch 15 is installed on the base plate 21 a that constitutes the housing 20, and therefore can be operated smoothly and easily during the installation work of the wire buffer device 10.

[0052] Second Embodiment The configuration of a sliding portion 50 according to a second embodiment will be described with reference to Fig. 10. The sliding portion 50 includes a slider 31, a guide shaft 32, a support 51, a tube insertion portion 51a, a guide pin 52, and a guide groove 53. The sliding portions 50 are provided in a plurality of recesses 27 that are arranged at equal intervals along the outer edge of the base portion 21a.

[0053] The support body 51 is fixed to the slider 31 side and extends toward the recessed surface side of the recess 27. The support body 51 is provided with a tube insertion portion 51a and a guide pin 52. The tube insertion portion 51a is formed midway in the extension direction and is an insertion hole through which the annular portion 25a of the wire tube 25 is inserted. The guide pin 52 is attached and fixed to an end of the support body 51 and slides along a guide groove 53. The guide groove 53 is recessed in the recess 27 and is an elongated hole through which the guide pin 52 slides, and is formed along the extension direction of the guide shaft 32.

[0054] The sliding portion 50 having this configuration can guide the sliding direction of the slider 31 along the radial direction of the annular portion 25a with a simpler and less costly configuration.

[0055] The present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0056] As described above, the present specification discloses the following: (1) A wire buffer device disposed between a first feeder and a second feeder for controlling a slack amount of a welding wire between the feeders, the wire buffer device comprising: a wire inlet portion through which the welding wire is fed from the first feeder; a wire outlet portion through which the welding wire is fed toward the second feeder; a tube having a curved annular portion formed by crossing between the wire inlet portion and the wire outlet portion and through which the welding wire is inserted; a base provided with a storage area for storing the wire inlet portion, the wire outlet portion, and the annular portion of the tube; a sliding mechanism disposed in the storage area, the sliding mechanism including: a tube insertion portion through which the tube is inserted and which moves radially as the diameter of the annular portion expands or contracts; and a slider which moves together with the tube insertion portion; a crank mechanism including: a crankshaft journaled at a center position of the storage area; and a rod whose longitudinal ends are connected to the slider and the crankshaft, respectively, and which rotates the crankshaft as the slider moves. and a detection sensor for detecting the rotation angle of the crankshaft. According to this configuration, a rod connects the slider that slides in the radial direction of the annular portion to the crankshaft provided at the center of the accommodation area, and a detection sensor for detecting the rotation position of the crankshaft is provided, so that the buffer amount can be accurately detected while ensuring a sufficient buffer amount with a compact configuration.

[0057] (2) The wire buffer device according to (1), wherein the sliding mechanism has a ball bearing or a pin that moves along a surface direction of the base, and the ball bearing or the pin moves along a guide groove formed in the base in a radial direction of the annular portion. With this configuration, the slider can be reliably slid along the radial direction of the annular portion, so that the diameter of the annular portion can be smoothly expanded or contracted without losing its shape.

[0058] (3) The wire buffer device according to (1) or (2), wherein the tube is attached to either the wire inlet or the wire outlet. With this configuration, the radial extension and contraction of the annular portion of the wire tube into which the welding wire is inserted can be smoothed.

[0059] (4) The wire buffer device according to any one of (1) to (3), wherein the tube insertion section has a roller mechanism that clamps the tube. With this configuration, the wire tube inserted into the tube insertion section can slide smoothly without resistance, and therefore the radial sliding movement of the slider accompanying the radial expansion and contraction of the annular section also becomes smooth.

[0060] (5) The wire buffer device according to any one of (1) to (4), wherein at least two rods are provided, and the connecting portions between the rods and the crankshaft are arranged at equal intervals on the outer edge side of the crankshaft. With this configuration, the sliding movement of each rod is synchronized via the crankshaft, so that the radial extension and contraction of the annular portion can be performed without destroying the shape of the annular portion. Furthermore, when acceleration is applied to the wire buffer device, the loads applied to each rod cancel each other out, so that even if the wire buffer device is mounted on a welding robot or the welding robot moves at high speed, fluctuations in the diameter of the annular portion due to the influence of acceleration can be prevented.

[0061] (6) The wire buffer device according to any one of (1) to (5), further comprising a plurality of sleeves for guiding the tube, each sleeve having an inner diameter that allows the diameter of the annular portion to expand and contract within a predetermined range. With this configuration, when the diameter of the annular portion of the wire tube fluctuates, the wire tube can be prevented from being deteriorated by directly rubbing against the base side.

[0062] (7) A buffer amount control system including: the wire buffer device according to any one of (1) to (6); a push feeder serving as the first feeder that feeds the welding wire to the wire buffer device; a pull feeder serving as the second feeder to which the welding wire is fed from the wire buffer device; and a control unit. With this configuration, the buffer amount detected by the wire buffer device can be fed back to the first feeder and the second feeder, thereby making the control of welding wire feed by the first feeder and the second feeder more stable.

[0063] (8) A welding system including: a welding robot equipped with the wire buffer device according to any one of (1) to (6); and a welding power source. According to this configuration, by feeding back the buffer amount detected by the wire buffer device to the first feeder and the second feeder, the feed amount of the welding wire fed to the welding torch is stabilized, resulting in improved welding accuracy.

[0064] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0065] This application is based on a Japanese patent application (Patent Application No. 2023-116851) filed on July 18, 2023, the contents of which are incorporated herein by reference.

[0066] 10 Wire buffer device 15 Auxiliary switch 20 Storage section 20a Introduction area 20b Storage area 20c Delivery area 21 Base 21a Base section (surface of base) 21b Edge section 22 Wire inlet section 23 Wire outlet section 24 Guide section 25 Wire tube (tube) 25a Annular section 26 Protective sleeve (sleeve) 26A First protective sleeve 26B Second protective sleeve 26C Third protective sleeve 26D Fourth protective sleeve 26E Fifth protective sleeve 27 Recess 27A First recess 27B Second recess 27C Third recess 28 Lid section 29 Fixing magnet 30 Sliding section (sliding mechanism) 30A First sliding section 30B Second sliding section 30C Third sliding section 31 Slider 32 Guide shaft 33 Support plate 34 Tube insertion portion 35 Guide groove 36 Ball bearing 36a Contact surface 37 Roller 38 First support shaft 39 Second support shaft 41 Crank portion (crank mechanism, linkage mechanism) 42 Crank shaft 42a Shaft portion 42b Flange portion 43 Rod 43A First rod 43B Second rod 43C Third rod 44 Detection sensor 45 Sensor support plate 46A First connecting portion (connecting portion) 46B Second connecting portion (connecting portion) 46C Third connecting portion (connecting portion) 49 Bearing 50 Sliding portion 51 Support 51a Tube insertion portion 52 Guide pin (pin) 53 Guide groove 100 Welding system 110 Welding robot 111 Welding torch 120 Robot control device 130 Welding power source 131 Feeding control section (control section) 140 Servo amplifier 150 Pull feeder (second feeding device) 160 Push feeder (first feeding device) 200 Work

Claims

1. A wire buffer device disposed between a first feeding device and a second feeding device for controlling an amount of slack in a welding wire between the feeding devices, the wire buffer device comprising: a wire inlet portion through which the welding wire is fed from the first feeding device; a wire outlet portion through which the welding wire is fed toward the second feeding device; a tube through which the welding wire is inserted and whose annular portion is curved by crossing between the wire inlet portion and the wire outlet portion; a base having an accommodation area for accommodating the wire inlet portion, the wire outlet portion, and the annular portion of the tube; a sliding mechanism disposed in the accommodation area, the sliding mechanism having a tube insertion portion through which the tube is inserted and which moves in a radial direction as the diameter of the annular portion expands and contracts, and a slider which moves together with the tube insertion portion; a crank mechanism including a crankshaft journaled at a center position of the accommodation area, and a rod whose both longitudinal ends are connected to the slider and the crankshaft, respectively, and which rotates the crankshaft as the slider moves; a detection sensor that detects a rotation angle of the crankshaft.

2. A wire buffer device as described in claim 1, wherein the sliding mechanism has a ball bearing or pin that moves along the surface direction of the base, and the ball bearing or pin moves along a guide groove formed in the base in the radial direction of the annular portion.

3. The wire buffer device according to claim 1, wherein the tube is attached to either the wire inlet portion or the wire outlet portion.

4. The wire buffer device according to claim 1, wherein the tube insertion section has a roller mechanism for clamping the tube.

5. The wire buffer device according to claim 1, wherein at least two of the rods are provided, and connections between the rods and the crankshaft are disposed at equal intervals on the outer edge side of the crankshaft.

6. The wire buffer device according to claim 1, further comprising a plurality of sleeves for guiding the tube, the sleeves having an inner diameter that allows the diameter of the annular portion to expand and contract within a predetermined range.

7. A buffer amount control system comprising: a wire buffer device according to any one of claims 1 to 6; a push feeder which is the first feeding device that feeds the welding wire to the wire buffer device; a pull feeder which is the second feeding device to which the welding wire is fed from the wire buffer device; and a control unit.

8. A welding system comprising: a welding robot equipped with the wire buffer device according to any one of claims 1 to 6; and a welding power source.

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