Electric resistance welding equipment

Abstract

To provide an electric resistance welding device which can perform smooth welding work.SOLUTION: An electric resistance welding device 101 includes: an electrode chip 20 having a rivet pressing surface 21 for pressing a rivet W to one surface 10a of both surfaces 10a, 10b of a laminated body 10; a shaft member 30 which extends in an axial direction X and holds the electrode chip 20 on a shaft end part 30a; a cylindrical storage body 40 which stores the shaft member 30 in such a manner that the shaft member 30 can slide in the axial direction X; and a driving mechanism part 50 which drives the shaft member 30. The driving mechanism part 50 is configured to drive the shaft member 30 in the axial direction X relative to the storage body 40 between a lowered position P1 where the rivet pressing surface 21 of the electrode chip 20 protrudes from a tip part 44 of the storage body 40 in the axial direction X and an elevated position where the rivet pressing surface 21 of the electrode chip 20 and an inner wall surface of the tip part 44 of the storage body 40 form a housing recessed part S capable of housing the rivet W.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric resistance welding apparatus. [Background technology]

[0002] Conventionally, in vehicle welding equipment, a welding device is used that joins a plurality of metal plate materials that constitute a vehicle body by using electric resistance welding called RPW (resistance pierce welding). As disclosed in the following Patent Document 1, this welding device is configured to sandwich a laminate formed by stacking a plurality of metal plate materials in the plate thickness direction between a first electrode tip that presses one surface of the laminate through a rivet and a second electrode tip that presses the other surface, and to apply pressure and electricity. For example, in the case of a laminate formed by stacking aluminum plates and iron plates, the shank of the rivet penetrates the aluminum plate and generates a nugget between the aluminum plate and the iron plate by applying pressure and electricity, and the aluminum plate and the iron plate are joined by sandwiching the aluminum plate between the head of the rivet and the iron plate.

[0003] An example of this type of welding device is disclosed in the following Patent Document 2. In this welding device, one electrode tip is held by an elongated member with a circular cross section and housed in a cylindrical holder. This electrode tip is configured to form a housing recess capable of housing a nut between a pressing surface, which is an end surface in the axial direction, and an inner wall surface of a tip portion of the holder. According to this configuration, electric resistance welding can be performed by applying pressure and current to the stack by the pair of electrode tips while a nut is supplied to the housing recess and held in the housing recess. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-69499 A [Patent Document 2] JP 2017-60988 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of the welding device disclosed in the above Patent Document 2, the state in which the nut is accommodated in the accommodation recess is maintained before and after welding. Therefore, there is no escape route for the spatter generated during welding at the tip of the holder, and the spatter may adhere to and accumulate on the tip, partially blocking the opening of the accommodation recess. In this case, a problem may occur in which the nut cannot be supplied to the accommodation recess during the next welding. Therefore, work is required to remove the spatter accumulated on the tip of the holder, which hinders smooth welding work.

[0006] The present invention has been made in view of the above problems, and aims to provide an electric resistance welding apparatus capable of smoothly performing welding work. [Means for solving the problem]

[0007] One aspect of the present invention is A plurality of metal plates forming a laminate 、 An electric resistance welding device for joining using rivets, an electrode tip having a rivet pressing surface for pressing the rivet against either one of the two surfaces of the laminate; a shaft member extending in an axial direction and holding the electrode tip at a shaft end; a cylindrical housing that houses the shaft member so as to be slidable in the axial direction; a main driving means for moving the shaft member back and forth in the axial direction and fixed to a stationary member; The container is advanced and retreated in the axial direction. A drive mechanism; Equipped with the shaft member is moved by the main driving means to advance and retreat between a position where an accommodating recess is formed and a position where the rivet accommodated in the accommodating recess is pressed against the laminate; The container is moved by the drive mechanism to move back and forth between a position where the container recess is formed and a position where a tip portion of the container moves away from the laminate to form a space for scattering spatter when the laminate melts. Electric resistance welding equipment, is located. Effect of the Invention

[0008] In the electric resistance welding device of the above aspect, the electrode tip has a rivet pressing surface for pressing a rivet against either one of the two surfaces of a laminate made of a plurality of metal plates, and is held at an axial end of the shaft member. The shaft member is housed in a cylindrical housing and can be driven in the axial direction between a lowered position and an elevated position relative to the housing by a drive mechanism.

[0009] When the shaft member is in the lowered position, the rivet pressing surface of the electrode tip protrudes from the tip of the container in the axial direction. On the other hand, when the shaft member is in the raised position, the rivet pressing surface of the electrode tip and the inner wall surface of the tip of the container form a container recess capable of accommodating a rivet. Therefore, by first setting the shaft member to the raised position by the drive mechanism, the rivet can be temporarily held in the container recess during electric resistance welding.

[0010] Then, the shaft member is driven from the raised position to the lowered position by the drive mechanism, whereby the rivet can be pressed by the rivet pressing surface of the electrode tip and pushed out of the receiving recess. At this time, the stack can be clamped between the electrode tip pressed against one surface of the stack via the rivet and another electrode tip that is paired with the electrode tip and pressed against the other surface of the stack, and pressure and current can be applied. In this way, the multiple metal plates are electrically resistance welded using the rivet.

[0011] After the electric resistance welding is completed, the drive mechanism drives the shaft member from the lowered position to the raised position, creating an escape route for spatter generated during welding at the tip of the container, which prevents spatter from adhering to and accumulating at the tip of the container, and eliminates the problem of being unable to supply rivets to the container recess due to blockage caused by spatter during the next welding.

[0012] As described above, according to the above-mentioned aspects, it is possible to provide an electric resistance welding apparatus capable of smoothly performing welding work. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a side view of an electric resistance welding apparatus according to a first embodiment. [Diagram 2] 2 is a side view showing the electric resistance welding apparatus of FIG. 1 with a cover portion removed from a cylinder portion. [Diagram 3] 1 is a cross-sectional view showing a state in which a shaft member is in a raised position and a rivet is received in an receiving recess in the electric resistance welding device of the first embodiment. [Figure 4] 4 is a cross-sectional view showing a state in which the rivet has reached the laminate in the electric resistance welding apparatus of the first embodiment. FIG. [Diagram 5] 3 is a cross-sectional view showing the electric resistance welding apparatus of the first embodiment in a state where the cover portion is retracted. FIG. [Figure 6] 3 is a view of the cover portion of FIG. 2 as viewed from the direction of arrow A, and a cross-sectional view of the tip side of the cover portion. [Figure 7] FIG. 7 is a diagram for explaining the configuration of an opening in FIG. 6. [Figure 8] FIG. 3 is a perspective view showing a separation structure of the shaft member in FIG. 2. [Figure 9] FIG. 9 is a perspective view showing a modified example of the separation structure in FIG. 8 . [Figure 10] 5A to 5C are cross-sectional views showing a step-by-step process for joining two metal plate materials that form a laminate. [Figure 11] 11 is a cross-sectional view showing a bonding form of a laminate different from the laminate in FIG. 10. [Figure 12] 11 is a cross-sectional view showing a bonding form of a laminate different from the laminate in FIG. 10. [Figure 13] 6 is a cross-sectional view corresponding to FIG. 5 of an electric resistance welding apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Preferred embodiments of the above aspects are described below.

[0015] In the electric resistance welding apparatus of the above-mentioned aspect, it is preferable that the drive mechanism portion is configured such that a part of the container is a cylinder and a part of the shaft member is a piston rod, and the drive mechanism portion is provided with a piston that is accommodated in the cylindrical space of the cylinder so as to be slidable in the axial direction and is integrated with the piston rod, and an introduction portion that is connected to each of a plurality of working chambers formed by dividing the cylindrical space of the cylinder by the piston so as to be able to introduce fluid from a fluid supply source.

[0016] According to this electric resistance welding device, the drive mechanism is composed of a cylinder, a piston rod, a piston, and an introduction part. A fluid is selectively introduced from a fluid supply source into one of a plurality of working chambers through the introduction part, and the piston slides in the axial direction in the cylindrical space of the housing body, which is a cylinder. As a result, the shaft member constituting the piston rod slides in the axial direction integrally with the piston and is driven between a lowered position and an elevated position. At this time, by using a part of the shaft member that holds the electrode tip as the piston rod of the drive mechanism, it becomes easier to concentrate the load for driving the shaft member in the axial direction on the radial center side of the housing body. As a result, it is possible to stabilize the axial movement of the shaft member and improve reliability.

[0017] In the electric resistance welding apparatus of the above-mentioned aspect, it is preferable that the housing has a cylindrical cylinder portion that houses the piston and the piston rod, and a cylindrical cover portion attached to the tip of the cylinder portion, and the shaft member has a first shaft portion that is housed in the cylinder portion as the piston rod, and a second shaft portion that is interposed between the first shaft portion and the electrode tip and housed in the cover portion, and the second shaft portion is configured to be detachably connected to each of the first shaft portion and the electrode tip.

[0018] According to this electric resistance welding device, when replacing parts due to deterioration of the connection part with the electrode tip of the shaft member, the second shaft portion can be separated from the first shaft portion constituting the piston rod of the drive mechanism, and only the second shaft portion can be replaced. This makes it possible to keep the cost of replacement parts low. In contrast, if the entire shaft member is to be replaced, it is necessary to replace the cylinder portion in which the first shaft portion is incorporated as the piston rod, which increases the cost of replacement parts.

[0019] In the electric resistance welding apparatus of the above-mentioned aspect, the tip of the container is provided with an air outlet opening into the container recess, and an opening through which the rivet can be supplied to and discharged from the container recess, and when the opening is viewed in the axial direction, it is preferable that the opening has an opening shape having a circular region corresponding to the shape of the head of the rivet, and an expanded region formed by partially expanding an edge of the circular region radially outward as a passage for air ejected from the air outlet.

[0020] According to this electric resistance welding device, in addition to the circular area that allows the rivet to be fed into and discharged from the recessed portion, an expanded area is provided at the opening at the tip of the container, so that the expanded area of ​​the opening can provide a passage for the air ejected from the air outlet. Also, since there is no partition or other barrier at the boundary between the circular area and the expanded area, it is possible for some of the air ejected through the expanded area to flow into the circular area. This enhances the effect of blowing away spatter with air over the entire opening at the tip of the container.

[0021] Hereinafter, a specific structure of the electric resistance welding apparatus of this embodiment and a joining mode of a plurality of metal plate materials using this electric resistance welding apparatus will be described with reference to the drawings.

[0022] In the drawings for explaining this embodiment, unless otherwise specified, the axial direction of the shaft member that holds the electrode tip is indicated by arrow X, the radial direction of the housing that houses the shaft member is indicated by arrow Y, and the circumferential direction of the housing is indicated by arrow Z. Furthermore, a first direction that is one direction of the axial direction X is indicated by arrow X1, and a second direction that is the opposite direction to the first direction X1 is indicated by arrow X2.

[0023] (Embodiment 1) 1 and 2, an electric resistance welding apparatus (hereinafter, also simply referred to as a "welding apparatus") 101 of the first embodiment is a welding apparatus for joining two metal plate materials 11, 12 forming a laminate 10 by using a rivet W. The welding technique used for this joining is generally called "RPW (resistance pierce welding)".

[0024] The welding device 101 includes, as its main components, a pair of electrode tips 20, 20A, a shaft member 30, a container 40 constituting a sub-driving means, a driving mechanism section 50, and a main driving means 60.

[0025] The rivet W is a metal member that is generally used in electric resistance welding, and has a disk-shaped head Wa and a tapered shank Wb extending from the head Wa. The material of the rivet W is not particularly limited, and can be appropriately selected depending on the material of the metal plates 11 and 12 to be subjected to electric resistance welding.

[0026] Here, the laminate 10 is a laminate formed by stacking two metal plate materials 11, 12 in the plate thickness direction, i.e., overlapping them. An electrode tip 20 corresponds to one surface 10a of both surfaces 10a, 10b of the laminate 10, and another electrode tip 20A that forms a pair with the electrode tip 20 corresponds to the other surface 10b.

[0027] The electrode tip 20 is an electrode member pressed against one surface 10a of the laminate 10 via the rivet W, and is configured as a movable electrode here. At this time, the electrode tip 20 has a rivet pressing surface 21 for pressing the rivet W against one surface 10a, and the head Wa of the rivet W is pressed by this rivet pressing surface 21. The electrode tip 20A is an electrode member that is directly pressed against the other surface 10b of the laminate 10 in a state where it is arranged coaxially on the central axis L of the welding device 101. Here, the electrode tip 20A is configured as a fixed electrode on which the laminate 10 is placed. This electrode tip 20A is attached to a support arm 22. The rivet pressing surface 21 shown in the figure may be a flat surface, or it may be a gently spherical surface to adjust the surface pressure and current density.

[0028] As a result, the laminate 10 is clamped from both sides in the plate thickness direction by the pair of electrode tips 20, 20A. During welding, a welding current supplied from a welding transformer (not shown) flows between the pair of electrode tips 20, 20A. Both of the pair of electrode tips 20, 20A are preferably made of a copper alloy such as beryllium copper or chromium copper, which has excellent electrical conductivity and is tough.

[0029] Next, the shaft member 30 will be described.

[0030] The shaft member 30 is an elongated cylindrical shaft member (long member with a circular cross section) extending in the axial direction X, and is configured to hold the electrode tip 20 by joining to its shaft end portion 32a. This shaft member 30 is also generally called a "shank." This shaft member 30 is made of a material having conductivity to form a current path leading to the electrode tip 20, and is integrated with the electrode tip 20 to form an electrode. For this reason, the shaft member 30 is preferably made of the same type of copper alloy with good conductivity as the electrode tip 20. In order to increase the current flow efficiency, it is preferable to make the cross-sectional area of ​​the shaft member 30 as large as possible.

[0031] The shaft member 30, details of which will be described later, has a first shaft portion 31 that is housed in a cylinder portion 41 as a piston rod, and a second shaft portion 32 that is interposed between the first shaft portion 31 and the electrode tip 20 and housed in a cover member 43 that serves as a cover portion.

[0032] Next, the main driving means 60 will be described.

[0033] The main driving means 60 is a driving member for moving the shaft member 30 back and forth in the axial direction X. Various means for achieving this can be used, such as an air cylinder, a hydraulic cylinder, or a forward / backward output type electric motor. Here, an air cylinder 61 is used. The air cylinder 61 is firmly attached to a stationary member 62 such as the machine frame of the welding device 101. Since the main driving means 60 is firmly fixed to the stationary member 62 in this way, as described below, it is possible to directly move only the shaft member 30 back and forth, or to change the relative position of the shaft member 30 and the housing 40 or to keep it unchanged.

[0034] In the air cylinder 61, a piston rod 63 connected to a piston 65 is coupled to the shaft member 30 via a joint structure 64. Therefore, when air is supplied from an air supply source 61a and the piston rod 63 advances or retreats in the axial direction X via the piston 65, the shaft member 30 also advances or retreats in the axial direction X. The retreated position of the piston rod 63 is the position where an installation recess S, which will be described later, is formed, and the advanced position of the piston rod 63 is the position where the rivet W is pressed against the laminate 10.

[0035] Next, the container 40 constituting the driving sub-means will be described.

[0036] The container 40 is a member that moves forward and backward relative to the shaft member 30. As the drive mechanism 50, which is the means for realizing this, an air cylinder or the like can be adopted, similar to the main drive means 60. Here, an air cylinder system is used.

[0037] The drive mechanism 50 is configured with the cylinder portion 41, which is part of the container 40, as a piston cylinder, and the first shaft portion 31, which is part of the shaft member 30, as a piston rod, and is equipped with a piston 51 and an introduction portion 52 in addition to the piston cylinder and the piston rod.

[0038] The piston 51 is accommodated in the cylinder space 42 of the cylinder portion 41 (cylinder) together with the first shaft portion 31 (piston rod) of the shaft member 30. The piston 51 is accommodated in the cylinder space 42 so as to be slidable in the axial direction X, and is integrated with the first shaft portion 31 (piston rod) of the shaft member 30.

[0039] The introduction parts 52 are provided at two positions spaced apart from each other in the axial direction X of the cylinder part 41. The two introduction parts 52 are connected to two working chambers 42a, 42b formed by dividing the internal space 42 of the cylinder part 41 by the piston 51 so as to be able to introduce and discharge air from a working air selector valve 53 serving as a fluid supply source. The working air selector valve 53 is electrically connected to a control device 54 and is controlled in response to a control signal input from the control device 54.

[0040] The working air selector valve 53 is connected to two introduction ports 52 on the cylinder portion 41 side, as well as two introduction ports 43a provided in the cover member 43. The introduction ports 43a communicate with an air flow path 43b provided in the cylindrical wall of the cover member 43 so as to extend in the axial direction X. The air flow path 43b communicates with an air outlet 47 that opens into the installation recess S. Therefore, air introduced from the working air selector valve 53 to each introduction port 43a is ejected from the air outlet 47 into the installation recess S through the air flow path 43b of the cover member 43. This allows spatters generated during welding to be blown away by the air ejected into the installation recess S.

[0041] The structure of the air flow structure is simplified because the air flow path 43b is formed integrally with the cover member 43. At the same time, the opening position of the air outlet 47 can be set at an optimal position for discharging spatters, etc.

[0042] The drive mechanism 50 is configured to drive the shaft member 30 relative to the housing 40 in the axial direction X between a lowered position P1 (see lowered position P1 in FIG. 5) and an elevated position P2 (see elevated position P2 in FIG. 3). Here, the lowered position P1 is a position at which the shaft member 30 is disposed so that the rivet pressing surface 21 of the electrode tip 20 protrudes from the tip 44 of the housing 40 in the axial direction X. In contrast, the elevated position P2 is a position at which the shaft member 30 is disposed so that the rivet pressing surface 21 of the electrode tip 20 and the tip 44 of the housing 40 form an accommodation recess S.

[0043] The housing 40 constitutes a cylindrical housing that houses the shaft member 30 slidably in the axial direction X (first direction X1 and second direction X2). The shaft member 30 passes through the center of a cylindrical cylinder portion 41, and a piston 51 is fixed to the shaft member 30, and the piston 51 slides relatively within the cylinder portion 41 in an airtight state. End caps 41c and 41e that close both ends are airtightly coupled to the cylinder portion 41. The shaft member 30 passes through both end caps 41c, 41e in an airtight and slidable state.

[0044] When the electrode tip 20 side is the tip side, the container 40 has a cylindrical cylinder portion 41 extending from a tip end 41a to a rear end 41b, and a cylindrical cover member 43 extending from a tip end 44 to a rear end 45. The rear end 45 of the cover member 43 is connected to the tip end 41a of the cylinder portion 41, so that the cylinder portion 41 and the cover member 43 are integrated, and the cylinder space of the cylinder portion 41 and the cylinder space of the cover member 43 are configured to communicate in the axial direction X. In this case, the tip end 44 of the cover member 43 becomes the tip of the container 40.

[0045] In the cylinder portion 41, working chambers 42a and 42b into which working air is introduced are formed above and below the piston 51. When the piston 51 is stationary due to the operation of the main driving means 60, working air is supplied to either the working chamber 42a or 42b, and working air is discharged from the opposite working chamber 42b or 42a, causing only the cylinder portion 41 to move forward or backward relative to the other. This is because the pressure of the working air acts on the inner end surface of either the end cover 41c or the end cover 41e.

[0046] When working air is supplied to the working chamber 42a and discharged from the working chamber 42b, the cylinder portion 41 rises relatively and is placed in the raised position. On the other hand, when the piston 51 is stationary, working air is supplied to the working chamber 42b and discharged from the working chamber 42a, the cylinder portion 41 falls relatively and is placed in the lowered position. In this manner, the driving source of the housing 40 is the working air supplied to and discharged from the working chambers 42a and 42b.

[0047] Therefore, the housing 40 performs a driving function by the cylindrical cylinder portion 41 moving forward and backward relative to the stationary piston 51. When the housing 40 is configured with a forward and backward output type electric motor, the case member of the electric motor corresponds to the cylinder portion 41, and the screw shaft of the electric motor corresponds to the shaft member 30.

[0048] Next, the supply and exhaust of the working air will be explained.

[0049] The working air selector valve 53 operates according to signals sent from a control device 54 such as a sequence circuit or a computer device. Working air from a compressed air supply source switches the working air selector valve 53 according to command signals from the control device 54 to move the cylinder portion 41 back and forth and to inject air from the air outlet 47. An air pipe extending from the working air selector valve 53 is connected to the working chambers 42a, 42b and the air flow path 43b, and command signals from the control device 54 are transmitted to the working air selector valve 53 so that the operations described below are performed in a predetermined sequence.

[0050] The working air selector valve 53 can also be used as the air supply source 61a of the main driving means 60 to move the piston rod 63 back and forth.

[0051] Next, the accommodation recess will be described.

[0052] A cover member 43 is provided integrally with the cylinder portion 41 in order to accommodate the electrode tip 20 and to form an accommodating recess S described below. The cover member 43 surrounds and protects the rivet W and the electrode tip 20, and also provides an air flow path 43b described below. The cover member 43 is made of a cylindrical member having a smaller diameter than the cylinder portion 41. The cylinder portion 41 and the cover member 43 are disposed on the central axis L.

[0053] In order to facilitate understanding of the configuration of the above-mentioned receiving recess S, it is illustrated in an enlarged scale in FIG.

[0054] The storage space S for the rivet W is located at the end of the cover member 43. The space for storing the rivet W is formed by at least the rivet pressing surface and the inner shaped portion of the tip of the cover member. To achieve this, various structures can be adopted, such as providing an end plate that closes the cylindrical end of the cover member 43 and providing an opening in the center, or pressing a separate member into the end of the cover member 43 to form the storage space there. Here, an example of the latter separate member is shown.

[0055] A thick plate-like circular member 59 is press-fitted into the inside of the tip portion 44, a circular hole is drilled in the center of the circular member 59, and the circular region 48a is formed by the inner wall surface 59a, forming the storage space S for the rivet W. The inner diameter of the circular region 48a is slightly larger than the diameter of the head Wa of the rivet W. The circular member 59 is press-fitted as described above, but instead, the circular member 59 may be welded to the end surface of the cover member 43.

[0056] The rivet pressing surface 21 of the electrode tip 20 is located at the back in the direction of the central axis L of the circular hole opened in the circular member 59. In other words, the rivet pressing surface 21 forms the ceiling surface of the accommodating recess S. When the rivet pressing surface 21 is in a position serving as the ceiling surface, the main driving means 60 is in a raised position. At the same time, the cover member 43, which is advanced and retreated by the accommodating body 40, is in its most advanced position. In other words, the accommodating recess S is formed by the rivet pressing surface 21 and the inner surface of the circular region 48a.

[0057] As described above, the rivet pressing surface 21 of the electrode tip 20 and the inner wall surface 59a of the tip portion 44 of the container 40 form an accommodating recess S capable of accommodating the rivet W. The tip portion 44 is provided with an air outlet 47 that opens into the accommodating recess S, and an opening 48 through which the rivet W can be supplied to and discharged from the accommodating recess S. An annular permanent magnet 46 is provided on the inner periphery of the tip portion 44. This permanent magnet 46 has the function of attracting and holding the metal rivet W supplied to the accommodating recess S.

[0058] The height dimension of the rivet W as viewed in the direction of the central axis L is determined by selecting the thickness of the circular member 59 and the height position of the tip face 44b (see FIG. 6(b)) of the cover member 43 so that the shank Wb protrudes slightly from the tip face 44b when the rivet W is in close contact with the rivet pressing surface 21. In FIG. 6(b), the protruding length of the shank Wb of the rivet W protruding from the tip face 44b is indicated as T1.

[0059] Next, the air passage will be described.

[0060] The cylindrical member forming the cover member 43 is provided with air flow paths 43b in the direction of the central axis L. Four air flow paths 43b are provided at 90 degree intervals as viewed in the circumferential direction of the cover member 43, and open into the annular downward surface 47a shown in Figure 6(b). This opening is the air outlet 47.

[0061] Next, the extension region will be described.

[0062] An expansion region 48b is formed in communication with the circular region 48a. As shown in Fig. 6(a), the relative positions of the air outlet 47 and the expansion region 48b are set so that the air outlet 47 corresponds to the approximate center of the expansion region 48b. The expansion region 48b is circular, but may be rectangular. The circular region 48a and the expansion region 48b are in communication with each other.

[0063] As shown in Figures 6 and 7, when the opening 48 of the tip portion 44 of the container 40 is viewed in the axial direction X (specifically, in the direction of arrow A in Figure 2), the opening 48 has an opening shape having a circular region 48a and multiple expansion regions 48b.

[0064] In FIG. 7, for ease of explanation, the circular region 48a and the expanded region 48b are each hatched (cross-hatched) to clearly show the shapes of the circular region 48a and the expanded region 48b.

[0065] The circular region 48a is a concentric region corresponding to the shape of the head Wa (see FIG. 3) of the rivet W. The inner diameter of the circular region 48a is set to a dimension that is the outer diameter of the head Wa plus a predetermined gap for feeding the rivet W.

[0066] Each expansion area 48b is an area formed by partially expanding the edge of the circular area 48a radially outward as a passage for the air ejected from the air ejection port 47. In this case, each expansion area 48b is a dedicated area for ejecting the air ejected from the air ejection port 47 from the tip end 44 of the containing body 40.

[0067] The multiple expansion regions 48b are preferably disposed at approximately equal intervals in the circumferential direction Z. This allows air to be ejected in a well-balanced manner in the circumferential direction Z, and scattered spatters and the like can be effectively removed. Note that the shape and number of the expansion regions 48b are not limited to those shown in Figs. 6 and 7, and can be appropriately changed depending on design conditions such as the amount of ejected air and pressure loss.

[0068] The air flow path 43b is formed by drilling holes in the thick portion of the cover member 43, but instead of this, a thin tube member may be fixed to the inner surface of the cover member 43. In addition, working air is supplied from the working air selector valve 53 to the air flow path 43b.

[0069] Next, the rivet suction means will be described.

[0070] When the rivet W is received in the receiving recess S and is in close contact with the rivet pressing surface 21, it is necessary to prevent the rivet W from dropping or becoming displaced. For this purpose, a suction means is employed for the rivet W. As the suction means, various means can be used, such as air suction or magnetic suction. Here, the latter magnetic suction force is used.

[0071] That is, an annular permanent magnet 46 is fitted into the inner periphery of the tip portion 44. The attractive force of this permanent magnet 46 holds the rivet W in the correct position within the installation recess S. Instead of the annular permanent magnet 46, a plurality of rectangular or disk-shaped permanent magnets may be embedded in the circular member 59. In this manner, the permanent magnet 46 is disposed in the vicinity of the installation recess S.

[0072] Of the magnetic attractive force acting on the rivet W, the force component acting in the direction of the central axis L causes the rivet W to be attracted to the rivet pressing surface 21. In order to make the magnetic attractive force acting on the rivet W stronger, it is preferable to make the circular member 59 and the cover member 43 (tip portion 44) from a non-magnetic material such as stainless steel. The permanent magnet is positioned in the vicinity of the installation recess S from the above-mentioned perspective.

[0073] Next, the restricting member of the container will be described.

[0074] A restricting member is disposed to limit the relative position between the housing 40 and the shaft member 30. Various structures can be adopted for arranging the restricting member, but here, a long hole 66 is formed in the outer circumferential surface of the piston 51 in the direction of the central axis L, and a restricting member 67 connected to the cylinder portion 41 is inserted into the long hole. The shape of the restricting member 67 is, for example, a round bar type. The point where the restricting member 67 hits the inner end of the long hole 66 due to relative displacement is the limit stop position. The length of the long hole 66 is made to match the distance between the upper limit position and the lower limit position of the cylinder portion 41. In other words, the most advanced position and the most retracted position of the housing 40 with respect to the shaft member 30 are determined.

[0075] Next, the connection structure between the shaft member and the electrode tip will be described.

[0076] 8, it is preferable that the shaft member 30 has a separation structure in which the second shaft portion 32 is detachably connected to each of the first shaft portion 31 and the electrode tip 20. According to this separation structure, by dividing the shaft member 30 into two, it is possible to make the first shaft portion 31 a durable part that is replaced less frequently, and the second shaft portion 32 a replaceable part that is replaced more frequently.

[0077] A male thread is provided on the outer peripheral surface of each of one shaft end 32a and the other shaft end 32b in the axial direction X of the second shaft portion 32. A female thread is provided on the inner peripheral surface of the cylindrical portion 20a of the electrode tip 20, into which the male thread of the shaft end 32a of the second shaft portion 32 can be screwed. A female thread is provided on the inner peripheral surface of the cylindrical shaft end 31a of the first shaft portion 31, into which the male thread of the shaft end 32b of the second shaft portion 32 can be screwed.

[0078] For this reason, when using the electrode tip 20, the first shaft portion 31 and the second shaft portion 32 are screwed together, and the second shaft portion 32 and the electrode tip 20 are screwed together. At this time, the length in the axial direction X can be adjusted by finely adjusting the screwed state of the second shaft portion 32 and the electrode tip 20. Furthermore, when replacing the electrode tip 20, which is a consumable item, the screwed state of the second shaft portion 32 and the electrode tip 20 is released.

[0079] In contrast, when the second shaft portion 32 of the shaft member 30 deteriorates, the connection between the first shaft portion 31 and the second shaft portion 32 is released by releasing the screw engagement between the first shaft portion 31 and the second shaft portion 32. At this time, the second shaft portion 32 can be separated from the first shaft portion 31 and replaced by the simple operation of releasing the screw engagement.

[0080] As shown in Fig. 9, the separation structure of the shaft member 30 can be changed from that shown in Fig. 8. In this separation structure, the outer circumferential surface of the shaft end 32a of the second shaft portion 32 is a tapered surface, and the inner circumferential surface of the cylindrical portion 20a of the electrode tip 20 is a tapered surface into which the shaft end 32a of the second shaft portion 32 can be press-fitted. Therefore, when using the electrode tip 20, the second shaft portion 32 and the electrode tip 20 are connected to each other by press-fitting the shaft end 32a of the second shaft portion 32 into the cylindrical portion 20a of the electrode tip 20 and matching the tapered surfaces.

[0081] According to the separated structure shown in Fig. 9, by forming the axial end 32a of the second shank 32 into a tapered surface, the second shank 32 can be manufactured more inexpensively than in the separated structure shown in Fig. 8. Also, because the axial end 32a of the second shank 32 is press-fitted into the cylindrical portion 20a of the electrode tip 20, the operation of connecting and disconnecting the second shank 32 and the electrode tip 20 can be performed even more easily.

[0082] Next, the operation of the welding device 101 that joins the two metal plates 11, 12 that form the laminate 10 with the rivet W will be described mainly with reference to FIG.

[0083] Note that the materials of the two metal plates 11, 12 and the rivet W are not particularly limited, but here, an example is shown in which an aluminum plate is used for the metal plate 11, an iron plate is used for the metal plate 12, and the rivet W is made of iron, which is the same type of magnetic material as the metal plate 12.

[0084] (Formation of Recessed Storage Area) FIG. 10(a) shows a state in which the receiving recess S is formed and the rivet W is received therein, and the device as a whole corresponds to FIG. Air is supplied to the air cylinder 61 from the air supply source 61a. 2, the piston 65 of the main driving means 60 is in the most retracted position. As a result, the shaft member 30 is raised to the most retracted position, that is, the raised position P2, and the rivet pressing surface 21 stops at the raised position P2. At this stage, the piston 51 is in a stationary state.

[0085] Subsequently, when the working air from the working air switching valve 53 is supplied to the working chamber 42b and discharged from the working chamber 42a at the same time, the air pressure acting on the end cover 41c of the cylinder portion 41 causes the cylinder portion 41 to descend and the accommodation body 40 (the tip portion 44 of the cover member 43) is placed in the most advanced position. In this state, the regulating member 67 abuts against the lower end of the elongated hole 66, so that the lowest position of the accommodation body 40 relative to the shaft member 30 is determined. Through this operation, an accommodation recess S is formed in the tip portion 44 of the cover member 43.

[0086] Next, when the rivet W is inserted into the receiving recess S by using a parts supply device or the like, the rivet W is attracted to the rivet pressing surface 21 by the attractive force of the permanent magnet 46. At this time, the tip of the rivet W slightly protrudes from the tip surface 44b (see FIG. 6(b)) of the cover member 43 by a protruding length T1 (see FIG. 3).

[0087] (Rivet advancement and pressure) 10(b) shows a state in which the relative position of the installation recess S and the tip portion 44 remains unchanged, i.e., the relative position of the cylinder portion 41 and the shaft member 30 remains unchanged, working air is supplied to the air cylinder 61, the piston 65 descends, and the rivet W is pressed against the surface of the laminate 10 while remaining housed in the installation recess S. The device as a whole corresponds to FIG.

[0088] Since the above-mentioned pressurization is maintained, there is a small gap between the piston 65 shown in Fig. 4 and the inner end surface of the air cylinder 61. This gap is indicated by the reference symbol T3. In this state, the distance between the tip 44 of the cover member 43 and the laminate 10 is significantly short, and the installation recess S and the rivet W are surrounded and protected by the tip 44 of the cover member 43. The short distance between the tip 44 of the cover member 43 and the laminate 10 is indicated by the reference symbol T1 in Fig. 4.

[0089] (Retraction of cover) In FIG. 10(c), the rivet W is pressed against the laminate 10, and only the cover member 43 is pulled up, so that the tip 44 of the cover member 43 is moved away from the laminate 10. The entire device corresponds to FIG. 5. The main driving means 60 is in the same advanced position as in FIG. 4, and this time, the working air switching valve 53 is switched to supply working air to the working chamber 42a and exhaust air from the working chamber 42b. As a result, the housing 40 moves backward, so that the cover member 43 moves backward, and only the electrode tip 20 protrudes from the tip 44 of the cover member 43, and the distance between the tip 44 of the cover member 43 and the laminate 10 is enlarged. The enlarged distance is indicated by the symbol T2 in FIG. 5. In this state, the regulating member 67 abuts against the upper end of the long hole 66, so that the upper limit position of the housing 40 relative to the shaft member 30 is determined. At this stage, no melting phenomenon has occurred between the rivet W and the metal plate 11, so the rivet pressing surface 21 is at the intermediate position P3.

[0090] (Welding current flow) Fig. 10(d) shows a state in which a welding current is being applied in the state shown in Fig. 10(c). This application of current generates current resistance heat (Joule heat) at the contact point between the rivet W and the laminate 10, and the metal plate 11 melts due to the continued pressure, pressing the shank Wb of the rivet W against the metal plate 12, forming a nugget N at the pressed joint. At this time, the gap T3 below the piston 65 has disappeared.

[0091] When the rivet pressing surface 21 forms the ceiling surface of the receiving recess S and is waiting for the rivet W to be inserted, the rivet pressing surface 21 is in the raised position P2. The stage at which the shank Wb of the rivet W comes into contact with the metal plate 11 is the intermediate position P3 shown in Figures 10(b) and 10(c). The position at which the nugget N is formed is the lowered position P1. In other words, the rivet pressing surface 21 is lowered by the thickness of the metal plate 11. At this time, the gap T3 of the main driving means 60 disappears.

[0092] (Re-creation of the storage recess) FIG. 10(e) shows a state where the electrode tip 20 and the recess S are retracted together without changing their relative positions. That is, the state shown in FIG. 10(e) is achieved by the retraction operation of the main driving means 60. At this stage, the laminate 10, which has been completely welded, can be removed. Next, when only the cover member 43 advances from the state shown in FIG. 10(e), the state shown in FIG. 10(f) is reached, in which the recess S is reformed and the laminate is prepared for the next rivet supply. The advancement of only the cover member 43 is achieved by supplying and exhausting air to the operating chambers 42a and 42b. Alternatively, it is also possible to retract the electrode tip 20 and the cover member 43 separately, rather than retracting them simultaneously.

[0093] When the two-layer laminate 10 melts, spatters scatter. Because the expanded spatial dimension (see T2 in FIG. 5) is provided as described above, the spatters scatter vigorously in the lateral direction, and the spatters heading toward the circular region 48a or the expanded region 48b are blown away by the air jetted from the air jet 47.

[0094] According to the above-mentioned first embodiment, the following advantageous effects can be obtained.

[0095] In the welding device 101 configured as above, when the shaft member 30 is in the lowered position P1, the rivet pressing surface 21 of the electrode tip 20 protrudes from the tip portion 44 of the housing body 40 in the axial direction X. On the other hand, when the shaft member 30 is in the raised position P2, the rivet pressing surface 21 of the electrode tip 20 and the inner wall surface 59a of the tip portion 44 of the housing body 40 form an accommodating recess S capable of accommodating the rivet W. For this reason, by first setting the shaft member 30 to the raised position P2 by the drive mechanism 50, the rivet W can be temporarily held in the accommodating recess S during electric resistance welding.

[0096] after that, Main driving means 60 By driving the shaft member 30 from the raised position P2 to the lowered position P1 by the rivet pressing surface 21 of the electrode tip 20, the rivet W can be pressed and pushed out of the installation recess S. At this time, the stack 10 is clamped between the pair of electrode tips 20, 20A and pressurized and current is applied, whereby the two metal plate materials 11, 12 are electrically resistance welded together using the rivet W.

[0097] After electric resistance welding is completed, Main driving means 60 By driving the shaft member 30 from the lowered position P1 to the raised position P2 by the above, an escape route for spatters generated during welding can be created at the tip portion 44 of the housing body 40. This makes it possible to prevent spatters from adhering to and accumulating on the tip portion 44 of the housing body 40, and it becomes possible to solve the problem of being unable to supply the rivet W to the housing recess S due to blockage caused by spatters during the next welding.

[0098] Therefore, according to the above-mentioned first embodiment, it is possible to provide the welding device 101 that can smoothly perform welding work.

[0099] According to the welding device 101 having the above-mentioned configuration, in the drive mechanism 50, air is selectively introduced from the working air switching valve 53 to one of the two working chambers 42a, 42b through the introduction part 52, so that the piston 51 slides in the axial direction X in the cylinder space 42 of the cylinder part 41 which is a cylinder. As a result, the shaft member 30 constituting the piston rod slides in the axial direction X together with the piston 51 and is driven between the lowered position P1 and the raised position P2. At this time, by using the first shaft part 31 which is a part of the shaft member 30 which holds the electrode tip 20 as the piston rod of the drive mechanism 50, the load for driving the shaft member 30 in the axial direction X is easily concentrated on the center side of the radial direction Y of the cylinder part 41. As a result, it is possible to stabilize the movement of the shaft member 30 in the axial direction X and improve the reliability.

[0100] According to the welding device 101 having the above-mentioned configuration, the second shaft portion 32 can be separated from the first shaft portion 31 of the shaft member 30, and only the second shaft portion 32 can be replaced. This makes it possible to keep the cost of replacement parts low. In contrast, if the entire shaft member 30 is to be replaced, it is necessary to replace the cylinder portion 41 in which the first shaft portion 31 is incorporated as a piston rod, which increases the cost of replacement parts.

[0101] According to the welding device 101 configured as above, in the opening 48 of the tip portion 44 of the container 40, in addition to the circular region 48a that allows the rivet W to be supplied to and discharged from the container recess S, an expansion region 48b is provided, so that a passage for the air ejected from the air ejection port 47 can be secured by the expansion region 48b of the opening 48. Also, since there is no partition or other barrier at the boundary between the circular region 48a and the expansion region 48b, it is possible for a portion of the air ejected through the expansion region 48b to flow toward the circular region 48a. This enhances the effect of blowing away spatter with air over the entire opening 48 of the tip portion 44 of the container 40.

[0102] More specific effects of the above-mentioned embodiment 1 are as follows.

[0103] An electrode tip 20 having a rivet pressing surface 21 is attached to a shaft member 30 which is moved forward and backward by a main driving means 60, a housing body 40 is provided in a state in which it can move forward and backward relative to the shaft member 30, a cover member 43 which houses the electrode tip 20 is integrated with the housing body 40, and a housing recess S which houses the rivet W is constituted by the rivet pressing surface 21 and, for example, a part of the inner surface of the cover member 43. Therefore, depending on the operating positions of the main driving means 60 and the housing body 40, a state in which the rivet pressing surface 21 retreats to form the housing recess S, a state in which the rivet W housed in the housing recess S advances and is pressed against the stack 10 while the relative positions of the electrode tip 20 and the tip portion 44 of the cover member 43 remain unchanged, and a separated state in which only the cover member 43 moves away from the stack 10 from this pressed state are formed, and after a welding current is passed through to complete welding, the electrode tip 20 and the cover member 43 advance and retreat to form the housing recess S.

[0104] In particular, in this embodiment, the advancing / retracting operation positions of the main driving means 60 and the advancing / retracting operation positions of the accommodating body 40 are set separately as their respective advancing / retracting operation positions, and at the same time, the advancing / retracting operations of both means are organically related. Therefore, it is possible to accurately set the positions of the electrode tip 20 and the cover member 43 according to various conditions, such as the formation of the accommodating recess S, the advancement of the rivet W, the pressing of the rivet W against the laminate 10, the retreat of the cover member 43, and the formation of the accommodating recess S by the advancement and retreat of the electrode tip 20 and the cover member 43 after current is passed through.

[0105] (Formation of Recessed Storage Area) In the state where the rivet pressing surface 21 is retracted to form the receiving recess S, the retracting operation of the main driving means 60 places the rivet pressing surface 21 in its most retracted position, and at the same time, the receiving body 40 is placed in its most advanced position, thereby forming the receiving recess S for the rivet W in the tip 44 of the cover member 43. In this way, a space for receiving the rivet W is reliably formed by the combined operation of the main driving means 60 and the receiving body 40. And even if any external force acts on the rivet W inserted in the receiving recess S, the rivet W will not shift position within the receiving recess S, and a reliable retention is achieved.

[0106] (Rivet advancement and pressure) In a state where the rivet W accommodated in the receiving recess S advances and is pressed against the stack 10 while the relative position between the electrode tip 20 and the tip 44 of the cover member 43 remains unchanged, the main drive means 60 performs an advancing operation while the relative position between the shaft member 30 and the receiving body 40 remains unchanged. As a result, the rivet W remains inserted in the receiving recess S, the relative position between the rivet W and the cover member 43 during the advancing movement remains unchanged, and the rivet W accurately reaches the target location of the stack 10. In this state, the distance T1 between the tip 44 of the cover member 43 and the stack 10 is extremely short, and the receiving recess S and the rivet W are surrounded and protected by the tip 44 of the cover member 43.

[0107] (Retraction of cover) In the separated state where only the cover member 43 moves away from the stack 10 from the state where the rivet W is pressed against the stack 10, the advance position of the main driving means 60 remains unchanged, and the cover member 43 moves back as the container 40 moves backward, so that only the electrode tip 20 protrudes from the tip 44 of the cover member 43, and the distance between the tip 44 of the cover member 43 and the stack 10 is increased (see T2 in FIG. 5). At this stage, the shaft Wb of the rivet W is in a position where it does not penetrate the first metal plate 11, that is, the rivet pressing surface 21 is in the intermediate position. The increase in the distance ensures a space necessary for the scattering of spatter during melting, and prevents the spatter from adhering to the rivet W or the container recess S, or from penetrating deep into the cover member 43. Looking at the overall operation from the beginning, from the moment the rivet W is accommodated in the accommodating recess S, it is surrounded by the tip of the cover member 43 until it reaches the laminate 10, and transitions to a state where it is pressurized by the electrode tip 20. This prevents the rivet W from falling out of the accommodating recess S or becoming misaligned, achieving highly accurate rivet transfer.

[0108] (Welding current flow) When the rivet pressing surface 21 of the electrode tip 20 is pressing the laminate 10, when a welding current is applied, the shaft Wb of the rivet W penetrates the first metal sheet 11 while melting it, and reaches the second metal sheet 12. In this state, melting continues and a nugget N is formed. Therefore, after the current is completely applied, the first metal sheet 11 is tightly sandwiched between the rivet W and the second metal sheet 12, and the integration of the laminate 10 is completed. This integrated structure ensures reliable welding of the metal sheets.

[0109] (Re-creation of the storage recess) After the nugget is formed, the electrode tip 20 and the cover member 43 retract while the relative positions of the electrode tip 20 and the cover member 43 remain unchanged, and the welded laminate 10 can be removed. After that, only the cover member 43 advances, the accommodation recess S is formed again, and the next welding operation is continued. As described above, when the electrode tip 20 and the cover member 43 retract while the relative positions of the electrode tip 20 and the cover member 43 remain unchanged, the electrode tip 20 and the cover member 43 are simultaneously separated from the opposing electrode tip 20A, so that the operation time can be shortened and the production efficiency can be improved. In addition, by advancing only the cover member 43 after the retraction, the accommodation recess S can be formed with only one operating stroke of the cover member 43, which is effective for simplifying the operation. Alternatively, when the electrode tip 20 and the cover member 43 are retracted separately instead of simultaneously, the accommodation recess S can be completed at the time when the retraction of both is completed, which is efficient for forming the accommodation recess S. In this manner, after the welding current is applied and welding is completed, the electrode tip 20 and the cover member 43 advance and retreat, and the accommodating recess S is formed.

[0110] As described above, by organically combining the operations and functions of the main driving means 60 and the container 40, it is possible to ensure excellent operation of the welding device 101, such as the formation of the container recesses described above and the pressurized supply of the rivet W in a favorable holding state.

[0111] By arranging the main components such as the main driving means 60, the shaft member 30, the housing 40, the cover member 43, the electrode tip 20, and the housing recess S on the central axis L of the device, the entire welding device 101 can be made slim, making it easier to use in places where space is limited.

[0112] Since the electrode tip 20 and the accommodating recess S are surrounded by the cover member 43, the rivet W and the electrode tip 20 can be prevented from interfering with neighboring members, making it easier to manage the welding device 101.

[0113] As a modification particularly related to the first embodiment, the joining configurations shown in Figs. 11 and 12 can be adopted.

[0114] 11(a) is a joining form in which three metal plate materials 11, 12, and 13 constituting a laminate 10 are joined. For example, aluminum plate materials are used for the metal plate materials 11 and 13, an iron plate material is used for the metal plate material 12, and the same type of iron rivet W as the metal plate material 12 is used. In this joining form, two rivets W are used, and the rivet pressing surfaces 21 of each of the pair of electrode tips 20 and 20A press the corresponding rivet W. In this case, a structure is adopted in which the shaft member 30 is driven by the drive mechanism unit 50 for each of the pair of electrode tips 20 and 20A.

[0115] 11(b), by applying pressure and current to the laminate 10 with a pair of electrode tips 20, 20A, the shank of one rivet W penetrates the metal sheet 11 to form a nugget N between the metal sheet 12, and the shank of the other rivet W penetrates the metal sheet 13 to form a nugget N between the metal sheet 12. Then, by sandwiching the metal sheet 11 between the head of one rivet W and the metal sheet 12, and sandwiching the metal sheet 13 between the head of one rivet W and the metal sheet 12, the three metal sheets 11, 12, and 13 are joined.

[0116] The joining form shown in Fig. 12(a) is a form in which two metal plate materials 11, 13 constituting a laminate 10 are joined. For example, aluminum plate materials are used for the metal plate materials 11, 13, and an iron rivet W is used. In this joining form, two rivets W are used, and the rivet pressing surfaces 21 of each of a pair of electrode tips 20, 20A press the corresponding rivet W. In this case, as with the joining form in Fig. 11(a), a structure is adopted in which the shaft member 30 is driven by the drive mechanism unit 50 for each of the pair of electrode tips 20, 20A.

[0117] 12(b), by applying pressure and current to the laminate 10 with a pair of electrode tips 20, 20A, the shank of one rivet W penetrates the metal sheet 11 and the shank of the other rivet W penetrates the metal sheet 13 to generate a nugget N between the two rivets W. The two metal sheets 11, 13 are then sandwiched between the head of one rivet W and the head of the other rivet W, thereby joining the two metal sheets 11, 13. In the case of this joining form, less energy is required for joining than when aluminum sheets are directly welded together.

[0118] Hereinafter, other embodiments related to the above-mentioned embodiment 1 will be described with reference to the drawings. In the other embodiments, the same elements as those in embodiment 1 are given the same reference numerals, and the description of the same elements will be omitted.

[0119] (Embodiment 2) As shown in FIG. 13, the welding device 102 of the second embodiment has a drive mechanism 150 for driving the container 40, which has a structure different from that of the drive mechanism 50 of the first embodiment.

[0120] The drive mechanism 150 includes a cylinder 151 provided separately from the housing 40, a piston 152 accommodated in the cylinder 151 so as to be slidable in the axial direction X, a piston rod 153 integrated with the piston 152, an introduction portion 154 for introducing air from the working air switching valve 53 into an operating chamber 151a in the cylinder 151, a spring member 155 that elastically biases the cylinder 151 in the compression direction of the operating chamber 151a, and a connecting plate 156 that connects the cover member 43 and the piston rod 153.

[0121] According to this drive mechanism 150, the pressure in the working chamber 151a increases due to the introduction of air from the introduction portion 154, and the upward load received from the working chamber 151a exceeds the elastic biasing force of the spring member 155, causing the piston 152 to slide in the second direction X2. At this time, the housing body 40 is pulled up and raised by the connecting plate 156, so that the shaft member 30 descends relative to the housing body 40. As a result, for example, the shaft member 30 at the raised position P2 can be lowered to the lowered position P1.

[0122] On the other hand, the piston 152 slides in the first direction X1 because the pressure in the working chamber 151a drops due to the stop of the introduction of air from the introduction portion 154, and the upward load received from the working chamber 151a falls below the elastic biasing force of the spring member 155. At this time, the housing body 40 is pulled down by the connecting plate 156 and lowered, so that the shaft member 30 rises relative to the housing body 40. As a result, for example, the shaft member 30 at the lowered position P1 can be raised to the raised position P2.

[0123] The other configurations are similar to those of the welding device 101 of the first embodiment.

[0124] According to the above-mentioned second embodiment, all the components of the drive mechanism 150 are disposed outside the housing 40, so that the replacement work of the components of the drive mechanism 150 is simple and the maintenance is excellent.

[0125] In a modification particularly related to the second embodiment, similar to the driving mechanism 50 of the first embodiment, the spring member 155 may be omitted and the piston 152 may be driven only by air.

[0126] In addition, the same effects as those of the first embodiment are achieved.

[0127] The present invention is not limited to the above-described embodiments, and various applications and modifications are possible without departing from the scope of the present invention. For example, the following embodiments may be applied to the present invention.

[0128] In the above embodiment, the case where air is used as the fluid for driving the pistons 51, 152 has been illustrated, but the type of fluid for driving the pistons 51, 152 is not limited to air, and a fluid other than air may be used as necessary. For example, a hydraulic drive system using hydraulic oil instead of air may be adopted.

[0129] In the above-described embodiment, an example was given of the opening 48 at the tip 44 of the container 40 having a circular region 48a and an expansion region 48b, but the shape of the opening 48 is not limited to this and can be changed as appropriate as necessary.

[0130] In consideration of the above-described embodiment and various modifications, the present invention can adopt the following aspect 1.

[0131] (Aspect 1) An electric resistance welding apparatus for joining a laminate formed by overlapping a plurality of metal plate materials using rivets, A main driving means of a forward and backward output type attached to a stationary member; a shaft member that is moved forward and backward by the main driving means; an electrode tip connected to a tip end of the shaft member, the tip end surface of which serves as a rivet pressing surface; a secondary driving means that moves forward and backward relative to the shaft member; a cover member integrated with the driving sub-means and configured to accommodate the electrode tip while extending in the same direction as the welding tip; a rivet receiving recess disposed at a tip end of the cover member, one of the inner surfaces of which is formed by at least the rivet pressing surface; Equipped with According to the operating positions of the main drive means and the sub drive means, a state in which the rivet pressing surface is retracted to form the receiving recess; a state in which the rivet advances and is pressed against the stack while the relative positions of the electrode tip and the front end of the cover member remain unchanged; A separated state is formed in which only the cover member is moved away from the stacked body from the pressed state, an electric resistance welding apparatus configured such that the electrode tip and the cover member advance and retreat to form the accommodating recess after a welding current is applied to complete welding.

[0132] According to this aspect 1, the following effects are achieved.

[0133] An electrode tip having a rivet pressing surface is attached to a shaft member moved forward and backward by the main driving means, a sub-driving means is provided in a state in which it can move forward and backward relative to the shaft member, a cover member for accommodating the electrode tip is integrated with the sub-driving means, and an accommodating recess for accommodating the rivet is constituted by the rivet pressing surface and, for example, a part of the inner surface of the cover member. Therefore, depending on the operating positions of the main driving means and the sub-driving means, a state in which the rivet pressing surface retreats to form the accommodating recess, a state in which the rivet accommodated in the accommodating recess advances and is pressed against the stacked body while the relative positions of the electrode tip and the tip of the cover member remain unchanged, and a separated state in which only the cover member moves away from the stacked body from the pressed state are formed, and after a welding current is passed through to complete welding, the electrode tip and the cover member advance and retreat to form the accommodating recess.

[0134] In particular, in the present invention, the advancing / retracting positions of the main driving means and the advancing / retracting positions of the sub-driving means are set separately as their respective advancing / retracting positions, and the advancing / retracting movements of both means are organically related, so that the positions of the electrode tip and the cover member can be accurately set according to various conditions, such as the formation of the receiving recess, the advancement of the rivet, the pressing of the rivet against the laminate, the retreat of the cover member, and the formation of the receiving recess by the advancement and retreat of the electrode tip and cover member after current is passed through.

[0135] (Formation of Recessed Storage Area) To explain the state in which the rivet pressing surface retracts and the rivet receiving recess is formed, the main driving means retracts the rivet pressing surface to its most retracted position, and at the same time, the sub-driving means retracts to its most advanced position, forming a rivet receiving recess at the tip of the cover member. In this way, a space for receiving the rivet is reliably formed by the combined action of the main driving means and the sub-driving means. And even if any external force acts on the rivet in the receiving recess, the rivet is not displaced within the receiving recess and is reliably held.

[0136] (Rivet advancement and pressure) To explain the state in which the rivet accommodated in the receiving recess advances and is pressed against the stack while the relative positions of the electrode tip and the tip of the cover member remain unchanged, the main drive means advances while the relative positions of the shaft member and the sub-drive means remain unchanged. As a result, the rivet remains in the receiving recess, and the relative positions of the rivet and the cover member during the advance movement remain unchanged, so that the rivet accurately reaches the target location on the stack. In this state, the distance between the tip of the cover member and the stack is significantly short, and the receiving recess and the rivet are surrounded and protected by the tip of the cover member.

[0137] (Retraction and Separation of Cover Members) Regarding the separation state in which only the cover member moves away from the stacked body from the state in which the rivet is pressed against the stacked body, the advance position of the main driving means remains unchanged, and the sub-driving means performs a retreating operation to retreat the cover member, so that only the electrode tip protrudes from the tip of the cover member, and the distance between the tip of the cover member and the stacked body is increased. At this stage, the rivet shaft is in a position where it does not penetrate the first metal plate material, that is, the rivet pressing surface is in the intermediate position. By increasing the distance, a space necessary for the spatter scattering during melting is secured, and it is possible to prevent the spatter from adhering to the rivet or the receiving recess, or from penetrating deep into the cover member. Looking at the overall operation from the beginning, the rivet is surrounded by the tip of the cover member from the time it is received in the receiving recess until it reaches the stacked body, and is pressed by the electrode tip, so that the rivet does not fall out of the receiving recess or become displaced, and a highly accurate rivet transfer is achieved.

[0138] (Welding current flow) When a welding current is applied while the rivet pressing surface of the electrode tip is pressing the stacked body, the rivet shaft penetrates the first metal sheet while melting it, and reaches the second metal sheet. In this state, the melting continues and a nugget is formed. Therefore, after the current is completely applied, the first metal sheet is tightly sandwiched between the rivet and the second metal sheet, and the stacked body is integrated. This integrated structure ensures reliable welding of the stacked body.

[0139] (Re-creation of the storage recess) After the nugget is formed, the electrode tip and the cover member retract while the relative positions of the electrode tip and the cover member remain unchanged, and the welded overlapping body can be removed. After that, only the cover member advances to form the accommodation recess again, and the next welding operation is continued. As described above, when the electrode tip and the cover member retract while the relative positions of the electrode tip and the cover member remain unchanged, the electrode tip and the cover member are simultaneously separated from the opposing electrode, so that the operation time can be shortened and production efficiency can be improved. In addition, by advancing only the cover member after the retraction, the accommodation recess can be formed with only one operating stroke of the cover member, which is effective for simplifying the operation. Alternatively, when the electrode tip and the cover member are retracted separately instead of simultaneously, the accommodation recess can be completed at the time when the retraction of both is completed, which is efficient for forming the accommodation recess. In this way, as described in the above embodiment 1, the electrode tip and the cover member advance and retract after the welding is completed by passing a welding current, and the accommodation recess is formed.

[0140] As described above, by organically combining the operations and functions of the main drive means and the sub drive means, it is possible to ensure excellent operation as an electric resistance welding device, such as the formation of the accommodating recess and the pressurized supply of the rivet in a favorable holding state.

[0141] By arranging the main components such as the main driving means, shaft member, secondary driving means, cover member, electrode tip, and accommodating recess on the central axis of the welding device, the entire welding device can be made slim, making it easier to use in places where space is limited.

[0142] Since the electrode tip and the accommodating recess are enclosed by the cover member, the rivet and the electrode tip are prevented from interfering with neighboring members, making it easier to manage the welding equipment. [Industrial Applicability]

[0143] As described above, the welding device of the present invention can reliably deliver the rivet to the target location and eliminates problems such as spatter scattering caused by the melting heat during welding. Therefore, it can be used in a wide range of industrial fields such as automobile body welding processes and sheet metal welding processes for home electrical appliances. [Explanation of symbols]

[0144] 10 Laminate 10a, 10b both sides 20,20A Electrode Tip 21 Rivet pressing surface 30 Shaft member 31 First shaft 32 Second shaft 32a Shaft end 40 Container (auxiliary drive means) 41 Cylinder section 41a Tip 42 Cylinder space 42a, 42b Working chamber 43 Cover member (cover part) 44 Tip 47 Air outlet 48 Aperture 48a Circular Area 48b Extension Area 50,150 Drive mechanism 51 Piston 52 Introduction 53 Air actuation switching valve (fluid supply source) 59a Inner wall 11,12,13 Metal plate material 101, 102 Electric resistance welding equipment (welding equipment) W Rivet Wa head P1 lowering position P2 Up position S Recessed part X-axis direction

Claims

1. An electric resistance welding apparatus for joining a plurality of metal plate materials forming a laminate using rivets, an electrode tip having a rivet pressing surface for pressing the rivet against either one of the two surfaces of the laminate; a shaft member extending in an axial direction and holding the electrode tip at a shaft end; a cylindrical housing that houses the shaft member so as to be slidable in the axial direction; a main driving means for moving the shaft member back and forth in the axial direction and fixed to a stationary member; A drive mechanism for moving the container forward and backward in the axial direction; Equipped with the shaft member is moved by the main driving means to advance and retreat between a position where an accommodating recess is formed and a position where the rivet accommodated in the accommodating recess is pressed against the laminate; An electric resistance welding apparatus in which the container is operated by the drive mechanism to move back and forth between a most advanced position where the container recess is formed and a position where the tip portion moves away from the laminate and forms a space for spatter dispersion when the laminate melts.

2. 2. The electric resistance welding apparatus according to claim 1, wherein the drive mechanism comprises a piston that is slidably accommodated in the axial direction in the cylindrical space of the cylinder and integrated with the piston rod, and an introduction portion that is connected to each of a plurality of working chambers formed by dividing the cylindrical space of the cylinder by the piston so as to be able to introduce fluid from a fluid supply source.

3. 3. The electric resistance welding apparatus according to claim 2, wherein the housing has a cylindrical cylinder portion that houses the piston and the piston rod, and a cylindrical cover portion attached to a tip portion of the cylinder portion, the shaft member has a first shaft portion that is housed in the cylinder portion as the piston rod, and a second shaft portion that is interposed between the first shaft portion and the electrode tip and housed in the cover portion, and the second shaft portion is configured to be detachably connected to each of the first shaft portion and the electrode tip.

4. 4. The electric resistance welding device according to claim 1, wherein the tip of the container is provided with an air outlet opening into the container recess and an opening through which the rivet can be supplied to and discharged from the container recess, and when the opening is viewed in the axial direction, the opening has an opening shape having a circular region corresponding to the shape of the head of the rivet and an expanded region formed by partially expanding an edge of the circular region radially outward as a passage for air ejected from the air outlet.

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