Joining method and image forming device

Abstract

To weld metal plates by securing a ventilation passage for discharging metal vapor.SOLUTION: A joining method joins a first galvanized steel plate 101 and a second galvanized steel plate 102. The joining method comprises: a fastening step of fastening the first galvanized steel plate 101 and the second galvanized steel plate 102 overlapping with each other, at a fastening position with a fastening member; and a welding step of welding the first galvanized steel plate 101 and the second galvanized steel plate 102 overlapping with each other, at a welding position. A distance d between the fastening position and the welding position in a direction intersecting with a plate thickness direction of the first galvanized steel plate 101 or the second galvanized steel plate 102 is 30 [mm] or more.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a welding technique for metal sheets such as frame members used in manufacturing the frame of an image forming apparatus or the like. [Background technology]

[0002] The frame of an image forming device, such as an electrophotographic or inkjet type, is formed by combining multiple frame members. Methods for joining the frame members together include joining by screws, rivets, and welding. The joining method of joining the frame members together by welding is widely used because it provides a more rigid frame structure than other joining methods and can stably ensure the positional accuracy of the frame members. When joining by welding, the frame members are heated during welding. This heat can cause distortion in the frame members.

[0003] To minimize distortion of the frame members, it is necessary to minimize the amount of heat applied to the frame members. One joining method that reduces the amount of heat applied to the frame members is the overlap joining method, in which two frame members to be joined are placed so that their respective surfaces overlap, and then joined by irradiating the overlapping surfaces with laser light. This joining method is widely used to join frame members of the frame of an image forming device.

[0004] The frame members that make up the frame of an image forming device are often made of galvanized steel sheets to ensure rust resistance. When lap welding is performed on steel sheets that are plated with a metal that has a lower boiling point than the melting point of the base metal sheet, such as galvanized steel sheets, vapor from the plated metal can remain between the overlapping and tightly fitting surfaces. The vapor from the plated metal can melt and cause blowholes in the welded joint, reducing the quality of the weld.

[0005] Therefore, in jigs and other devices that support overlapping frame members during welding, the pressing portion that presses the overlapping surfaces to prevent them from separating is made of an elastic member. In such a configuration, when metal vapor is generated, the pressing portion slightly escapes, forming a tiny gap between the members. The metal vapor is then discharged through this tiny gap between the members. The frame body of an image forming device is configured to mount multiple frame members from multiple directions. Therefore, the jigs that support the frame members are often configured to cover the frame body and are large in size.

[0006] As image forming devices become faster, they are becoming larger. Furthermore, an increasing number of image forming devices are being equipped with multiple modules equipped with image formation functions, each separated into multiple frames. Since the multiple frames are equipped with different modules, each has a different frame structure. If multiple large jigs are used to weld the multiple frames, multiple large jigs are required, resulting in a huge investment in the jigs and a huge amount of man-hours required for setup changes during production.

[0007] One method for joining frames that does not require a large-scale jig involves temporarily supporting the frame members before welding by using fastening members such as rivets to prevent the gap between the overlapping surfaces, allowing the frame to stand on its own without a jig, and then welding the frame. However, when the overlapping surfaces of the frame members are temporarily supported by fastening members, the fastening members lack elasticity, preventing minute gaps from forming between the overlapping surfaces of the frame members when metal vapor is generated. This makes it difficult to vent the metal vapor. Patent Document 1 discloses a joining method in which a step is provided at the welded joint to create a gap, forming an air passage for venting plated metal vapor. In this joining method, the gap is provided by the shape of the frame members, ensuring an air passage even after the frame members are temporarily supported, allowing metal vapor to be removed. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-94390 Summary of the Invention [Problem to be solved by the invention]

[0009] However, as described above, the frame of an image forming apparatus is constructed by attaching multiple frame members from multiple directions, resulting in multiple joints where each frame member is welded and joined, facing in multiple directions. Therefore, if the frame members are shaped to provide gaps between the overlapping surfaces to ensure a passage for the plating metal vapor, each of the multiple welds must have a stepped shape, resulting in a complex shape for the frame members. In other words, manufacturing a frame by combining multiple frame members in a complex manner increases the number of manufacturing processes for the frame members, as well as the number of mold surfaces and manufacturing man-hours.

[0010] In view of the above-mentioned problems, the main object of the present invention is to provide a joining method that can weld metal sheets while ensuring an air passage for discharging metal vapor, even in a frame structure in which a large number of metal sheets are attached from multiple directions. [Means for solving the problem]

[0011] The joining method of the present invention is a joining method for joining a first metal sheet and a second metal sheet, and includes a fastening process for fastening the overlapping first metal sheet and the second metal sheet with a fastening member at a fastening position, and a welding process for welding the overlapping first metal sheet and the second metal sheet at a welding position, characterized in that the distance between the fastening position and the welding position in a direction intersecting the thickness direction of the first metal sheet or the second metal sheet is a distance at which steam generated between the first metal sheet and the second metal sheet during the welding process elastically deforms at least one of the first metal sheet and the second metal sheet, creating a gap between the first metal sheet and the second metal sheet. In another aspect, the joining method of the present invention is a joining method for joining a first metal sheet and a second metal sheet, comprising a fastening process for fastening the overlapping first metal sheet and the second metal sheet with a fastening member at a fastening position, and a welding process for welding the overlapping first metal sheet and the second metal sheet at a welding position, characterized in that the distance between the fastening position and the welding position in a direction intersecting the thickness direction of the first metal sheet or the second metal sheet is 30 mm or more. The image forming apparatus of the present invention comprises an image forming unit, and a frame body that includes joined first and second metal sheets and supports the image forming unit, wherein the first and second metal sheets are fastened with fastening members at fastening positions, the first and second metal sheets are welded at welding positions, and the distance between the fastening position and the welding position in a direction intersecting the thickness direction of the first or second metal sheet is 30 mm or more. [Effects of the Invention]

[0012] According to the present invention, even in a frame configuration in which a large number of metal plates are attached from multiple directions, the metal plates can be welded while ensuring an air passage for discharging metal vapor. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] 1 is a flowchart showing a joining method. [Figure 4] (a) to (e) are schematic cross-sectional views of the vicinity of the joining point during welding. [Figure 5] FIG. 1 is a diagram illustrating the relationship between the gap and the tensile strength of the steel plate. [Figure 6] FIG. 1 is an explanatory diagram of the relationship between distance and tensile strength. [Figure 7] An explanatory diagram of the relationship between distance and the occurrence rate of blowholes. [Figure 8] FIG. 1 is a diagram illustrating the configuration of an inkjet recording apparatus. [Figure 9] FIG. 4 is a diagram illustrating the configuration of a frame of a fixing module. [Figure 10] FIG. [Figure 11] Exploded view of the fixing frame. [Figure 12] FIG. 10 is a diagram illustrating a state in which each frame of the fixing frame is temporarily supported. [Figure 13] Enlarged view of part B in Figure 12. [Figure 14] FIG. 10 is an explanatory diagram of a state in which the fixing frame is mounted on the welding device before the joining process. [Figure 15] An enlarged view of part B in Figure 12 after joining. [Figure 16] FIG. 10 is an explanatory diagram of a conventional temporary support jig for frame welding. [Figure 17] 10(a) to 10(c) are explanatory diagrams of a conventional frame joining method. [Figure 18] FIG. 10 is an explanatory diagram of the temporary support jig in a state in which the frame is supported. [Figure 19] FIG. 10 is an explanatory diagram of a state in which the temporary support jig is mounted on the welding device. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Regarding the joining method and the frame structure of the image forming apparatus described in the present embodiment, the dimensions, materials, shapes, relative positions, etc. of the components described are not intended to limit the scope of the present invention unless otherwise specified.

[0015] (Joining method) 1 and 2 are explanatory views of the joining method of this embodiment. Here, a method for welding galvanized steel sheets, which are metallic sheets to be joined, will be described. Fig. 1 is a top view of galvanized steel sheets joined by the joining method of this embodiment. Fig. 2 is a schematic cross-sectional view of the vicinity of the joining point.

[0016] The first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 are arranged so as to partially overlap each other. A hole 105 is formed in the first zinc-plated steel sheet 101, a hole 106 is formed in the second zinc-plated steel sheet 102, and a rivet 103 is provided through the hole 105 and the hole 106. The first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 are fastened by the rivet 103 so that the overlapping surfaces do not separate. A joining point 104 (welding position) by laser welding is located at a predetermined distance d from the center (fastening position) of the rivet 103 in a direction intersecting the thickness direction of the first zinc-plated steel sheet 101 (or the second zinc-plated steel sheet 102). A protrusion 111 is formed on the second zinc-plated steel sheet 102 as a mark of laser welding.

[0017] Fig. 3 is a flow chart showing a joining method for performing such laser welding, and Fig. 4 is a schematic cross-sectional view of the vicinity of the joining point during welding.

[0018] When laser welding is started, first, a first zinc-plated steel sheet 101 and a second zinc-plated steel sheet 102 are overlapped so that their respective portions are in close contact with each other (S101). Fig. 4(a) illustrates the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 during the overlapping process. A hole 105 provided in the first zinc-plated steel sheet 101 and a hole 106 provided in the second zinc-plated steel sheet 102 are aligned so as to be approximately coaxial.

[0019] After the overlapping step, the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 are fastened together as a temporary support so as to prevent separation in the vertical direction of the overlapping surfaces (S102). Specifically, as shown in FIG. 4(b), a rivet 103 is inserted as a fastening member into a hole 105 and a hole 106 that are aligned so as to be approximately coaxial. The rivet 103 fastens the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 together. The fastening step prevents separation between the contact surfaces of the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102.

[0020] After the fastening step, the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 are joined by welding (S103). Specifically, in the joining step, as shown in FIG. 4( c), a laser beam 107 output from a laser welding device (not shown) is irradiated at a position that is a predetermined distance d away from the center (fastening position) of the rivet 103. By irradiating the laser beam 107, a molten pool 108 is formed on the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102, as shown in FIG. 4( d). The molten pool 108 is fixed, thereby joining the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102. The irradiation position of the laser beam 107 becomes a joining point 104 between the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102.

[0021] When irradiated with laser light, vapor of zinc, which is the plating metal, is generated from both the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102. This is because the boiling point of zinc, which is the metal used as the coating material for coating the surfaces of the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102, is lower than the melting point of the base metal, steel sheet (iron). If the overlapping surfaces of the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 cannot be separated, the zinc vapor has nowhere to escape and remains in the molten pool 108. This can cause blowholes and the like.

[0022] In this embodiment, the joining point 104 is located at a predetermined distance d from a rivet 103 that regulates the separation between the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102. Therefore, when zinc vapor is generated between the overlapping surfaces of the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102, at least one of the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 can bend due to elastic deformation ( FIG. 4( d) ). In FIG. 4( d ), the base steel portion of the first zinc-plated steel sheet 101 is melted by a laser beam 107 to form a molten pool 108. When zinc vapor is generated, the tip side of the first zinc-plated steel sheet 101 is lifted above the molten pool 108 by the zinc vapor, causing bending. As a result, a gap 109 is generated between the overlapping surfaces during welding. The zinc vapor can be discharged from the gap 109 as exhaust gas 110.

[0023] After the joining process is completed, as shown in FIG. 4( e), a protrusion 111 is formed by welding on the surface of the first zinc-plated steel sheet 101 or the second zinc-plated steel sheet 102. The protrusion 111 is not necessarily formed on both the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102, but may be formed on one of them. Alternatively, the surface of the first zinc-plated steel sheet 101 or the second zinc-plated steel sheet 102 may be recessed at the joining point 104. The gap 109 formed by elastic deformation becomes smaller as the deformation returns to normal after the joining process. However, the molten pool 108 may flow into the gap 109, and the gap 109 may not return to its shape before the joining process.

[0024] (Tensile strength of joint) 5 is an explanatory diagram of the relationship between the gap 109 and the tensile strength of the steel sheets when a first zinc-plated steel sheet 101 and a second zinc-plated steel sheet 102 are overlapped and welded. As shown in the figure, if the gap 109 between the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 exceeds 0.4 mm, the weld strength is significantly reduced. For this reason, it is preferable that the gap 109 between the overlapping surfaces of the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 does not exceed 0.4 mm.

[0025] 6 is an explanatory diagram of the relationship between the distance d from the center (fastening position) of a rivet 103, which is a fastening member, to a welding joint 104, and the tensile strength. When the distance d from the center of the rivet 103, which prevents the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 from separating to the joint 104, becomes smaller, the tensile strength of the joint 104 tends to become significantly smaller.

[0026] Figure 7 is an explanatory diagram of the relationship between the distance d from the center (fastening position) of the rivet 103 to the joint point 104 and the rate of occurrence of blowholes. The rate of occurrence of blowholes tends to increase significantly as the distance d becomes smaller. Figure 7 shows that the phenomenon of the tensile strength of the joint point 104 decreasing as the distance d from the center of the rivet 103 to the joint point 104 becomes smaller, as explained in Figure 6, is thought to be mainly caused by the occurrence of blowholes. Therefore, by setting the distance d between the center of the rivet 103 and the joint point 104 to a predetermined distance or more, the occurrence of blowholes can be suppressed and the tensile strength can be made more stable.

[0027] In this embodiment, an example of welding will be described, in which the joining target is a thin galvanized steel plate used mainly for the frame of an image forming apparatus. The galvanized steel plate is assumed to have a plate thickness of 0.8 to 3.2 mm. The target tensile strength of the welding joint is 1500 N or more. Therefore, for a maximum plate thickness of 3.2 mm, the distance d from the center of rivet 103 to joint point 104 is set to 30 mm or more.

[0028] Considering the relationship between the deflection of the beam and the moment of inertia, it can be seen that the distance d is proportional to the thickness of the galvanized steel sheet. Therefore, it is preferable that the distance d is 9.3 times or more the thickness of the sheet. In this case, the thickness is the thickness of either the first galvanized steel sheet 101 or the second galvanized steel sheet 102, whichever steel sheet will deflect more when the gap 109 occurs. Typically, it is the thickness of the first galvanized steel sheet 101. Note that if the tensile strength of the joint 104 is not required to be high, the distance d from the center of the rivet 103 to the joint 104 may be less than 9.3 times the thickness of the sheet.

[0029] If the distance from the rivet 103 is too large, the gap between the steel sheets tends to become larger due to bending caused by the weight of the galvanized steel sheets or warping during processing. Therefore, in this embodiment, the distance d is set to 250 mm or less so that the gap between the steel sheets is 0.4 mm or less. Even in this case, this does not apply to locations where high tensile strength is not required at the joining point.

[0030] In the joining method of this embodiment, when performing lap welding of plate-shaped steel materials (sheet metal) by laser welding, it is not necessary to provide a part shape such as a step for discharging zinc vapor. Furthermore, the joining method of this embodiment does not require a step of performing two laser irradiations, such as removing zinc from the welding surface by irradiating with laser light and then performing actual welding, or a jig capable of forming an air passage for discharging zinc vapor. In the joining method of this embodiment, two thin steel plates are temporarily supported with a rivet 103, and then laser light is irradiated at a position a predetermined distance d away from the fastening position of the rivet 103 to join them. As a result, this embodiment enables welding that suppresses deterioration of welding quality due to the occurrence of blowholes, etc.

[0031] In this embodiment, zinc is used as the plating material having a boiling point lower than the melting point of the base steel sheet, but the plating material is not limited to this. Rivets are used as fastening members that suppress separation in the surface direction before the welding process, but the fastening member is not limited to this as long as it suppresses separation in the surface direction. The steel sheet that generates zinc vapor may be at least one of the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102. Welding is performed by heating with a laser beam, but the heating method is not limited to laser beam and may be any other heating method known in the field of welding (electricity, arc discharge, gas, plasma, electron beam, etc.).

[0032] (operation form) The frame structure of an image forming apparatus using the joining method of this embodiment will be described below, taking an inkjet recording apparatus as an example of the image forming apparatus.

[0033] 8 is a diagram illustrating the configuration of an inkjet recording apparatus. The inkjet recording apparatus 100 of this embodiment is a sheet-fed image forming apparatus that produces a finished product by forming an ink image on a sheet using two liquids: a reaction liquid and ink. The inkjet recording apparatus 100 includes a paper feed module 1000, a print module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, an inverting module 6000, and a paper discharge stacking module 7000. A cut sheet on which an image is to be printed is supplied from the paper feed module 1000, undergoes predetermined processing in each module, and is then discharged to the paper discharge stacking module 7000.

[0034] The paper feed module 1000 includes multiple (three tiers in this embodiment) storage cabinets 1100a-1100c. Each of the storage cabinets 1100a-1100c can store sheets. Each of the storage cabinets 1100a-1100c can be pulled out toward the front of the device, and is pulled out toward the front of the device to store sheets. The paper feed module 1000 feeds sheets one by one to the print module 2000. To achieve this, each of the storage cabinets 1100a-1100c is provided with a separation belt and a transport roller. Note that the number of storage cabinets 1100a-1100c is an example, and there may be one, two, four or more tiers.

[0035] The print module 2000 is an image forming unit that forms an image on a sheet fed from the paper feed module 1000. The print module 2000 includes a pre-imaging registration correction unit (not shown), a print belt unit 2200, and a recording unit 2300. The pre-imaging registration correction unit corrects the inclination and position of the sheet fed from the paper feed module 1000 and conveys the sheet to the print belt unit 2200.

[0036] The print belt unit 2200 and the recording unit 2300 are disposed facing each other across the sheet transport path, downstream of the pre-imaging registration correction unit in the sheet transport direction. The print belt unit 2200 adsorbs and transports the sheet transported from the pre-imaging registration correction unit. The recording unit 2300 is a sheet processing unit that forms an image by performing a recording process (printing) on ​​the sheet transported by the print belt unit 2200 from above using a recording head. The recording head prints by ejecting ink onto the sheet. As the sheet is adsorbed and transported by the print belt unit 2200, a constant clearance is maintained between the sheet and the recording head.

[0037] A plurality of recording heads are arranged along the sheet transport direction. The recording heads of this embodiment are five line-type recording heads corresponding to the four colors of Y (yellow), M (magenta), C (cyan), and K (black), as well as the reaction liquid. The number of colors and recording heads is not limited to five. The inkjet method can employ a method using a heating element, a method using a piezoelectric element, a method using an electrostatic element, a method using a MEMS element, or the like. Ink of each color is supplied to the recording head from an ink tank (not shown) via an ink tube.

[0038] The sheet printed by the recording unit 2300 is transported by the print belt unit 2200. An inline scanner (not shown) is disposed downstream in the transport direction from the recording unit 2300. The inline scanner is used to detect misalignment and color density of the image formed on the sheet and correct the printed image.

[0039] The drying module 3000 dries the sheet on which an image has been formed by the print module 2000. By drying the sheet, the drying module 3000 reduces the liquid component contained in the ink and improves the fixation of the ink to the sheet. The drying module 3000 includes a decoupling unit 3200, a drying belt unit 3300, and a hot air blowing unit 3400.

[0040] The sheet printed by the recording unit 2300 of the print module 2000 is transported to the decoupling unit 3200 in the drying module 3000. The decoupling unit 3200 weakly holds the sheet by air pressure from above and belt friction while transporting it. This prevents the portion of the sheet remaining on the print belt unit 2200 from shifting, while the sheet straddles the decoupling unit 3200 and the print belt unit 2200.

[0041] The sheet conveyed from the decoupling section 3200 is attracted to and conveyed by the drying belt unit 3300, and at the same time, hot air is blown onto the ink-applied surface (image printed surface) from the hot air blowing section 3400 arranged above the belt, drying the ink-applied surface. Note that the drying method may be configured by combining a method of applying hot air, a method of irradiating the sheet surface with electromagnetic waves (ultraviolet rays, infrared rays, etc.), or a conductive heat transfer method by contact with a heating element.

[0042] The fixing module 4000 heats the sheet dried in the drying module 3000 to dry the ink, thereby fixing the image to the sheet. The fixing module 4000 includes a fixing belt unit 4100 having an upper belt unit 4110 and a lower belt unit 4120. The fixing module 4000 passes the sheet conveyed from the drying module 3000 between the heated upper belt unit 4110 and lower belt unit 4120, thereby allowing the ink solvent to sufficiently penetrate (fix) the sheet.

[0043] The cooling module 5000 cools the sheet on which the image has been fixed by the fixing module 4000, solidifying the ink softened by heating and suppressing changes in the temperature of the sheet caused by downstream devices. The cooling module 5000 includes multiple cooling units 5001. The multiple cooling units 5001 cool the high-temperature sheet conveyed from the fixing module 4000. Each cooling unit 5001 is configured to increase the pressure inside the cooling box by drawing in outside air with a fan into the cooling box, and to cool the sheet by blowing air from nozzles formed in the conveyance guide onto the sheet. The multiple cooling units 5001 are arranged on both sides of the conveyance path, allowing the sheet to be cooled from both sides.

[0044] A transport path switching unit is provided inside the cooling module 5000. The transport path switching unit switches the transport path of the sheet depending on whether the sheet is transported to the reversing module 6000 or to a double-sided transport path used for double-sided printing.

[0045] During double-sided printing, the sheet is transported to a transport path below the cooling module 5000 and then transported through a double-sided transport path including the fixing module 4000, drying module 3000, print module 2000, and paper feed module 1000. The double-sided transport section of the fixing module 4000 is provided with a first reversing unit 4200 that reverses the sheet from front to back. The sheet is transported to the first reversing unit 4200, then reversed and transported toward the drying module 3000, thereby reversing the print side of the image. By passing through the first reversing unit 4200, printing on the back side of the sheet becomes possible. The sheet is then transported again to the pre-imaging registration correction unit, print belt unit 2200, and recording unit 2300 of the print module 2000, where it is printed.

[0046] The inversion module 6000 includes a second inversion unit 6400. The inversion module 6000 can invert the front and back sides of the conveyed sheet using the second inversion unit 6400. This allows the orientation of the front and back sides of the discharged sheet to be changed. The discharge stacking module 7000 includes a top tray 7200 and a stacking unit 7500. The discharge stacking module 7000 aligns and stacks the sheets conveyed from the inversion module 6000 on the top tray 7200 or the stacking unit 7500.

[0047] (Frame structure) As described above, the inkjet recording apparatus 100 is divided into the paper feed module 1000, print module 2000, drying module 3000, fixing module 4000, cooling module 5000, reversing module 6000, and paper discharge stacking module 7000. The inkjet recording apparatus 100 is provided with a frame for each module to support its internal configuration. Each frame supports a different internal configuration, and therefore each has a different configuration. Here, the frame of the fixing module 4000 will be described.

[0048] 9 is a structural example of the frame of the fixing module 4000. The frame of the fixing module 4000 is called a "fixing frame." The fixing frame 400 is formed by joining together a bottom frame 401, a rear frame 402, a right frame 403, a left frame 404, and a center shelf 405. The bottom frame 401, the rear frame 402, the right frame 403, the left frame 404, and the center shelf 405 are each formed by joining together a plurality of frame members.

[0049] Here, the configuration of the bottom plate frame 401 will be described. Fig. 10 is a diagram illustrating the configuration of the bottom plate frame 401. The bottom plate frame 401 is made up of 17 frame members of six types: a bottom plate 450, two horizontal beams 451, two vertical beams 452, four end diagonal beams 453, four central diagonal beams 454, and four central connecting beams 455. The frame members are joined by welding after being combined together.

[0050] The rear frame 402, right frame 403, left frame 404, and center shelf 405 are similarly composed of multiple frame members, which are similarly assembled and then joined by welding. To prevent deformation of the frame members due to welding, the welding used to join the frame members is preferably lap welding using laser welding, which has a relatively small heat input to the frame members. In particular, welding using the joining method of the present embodiment described above is preferred. For this reason, lap welding using laser welding is mainly used to join the frame members.

[0051] FIG. 11 is an exploded view of the fixing frame 400. As described above, the bottom frame 401, rear frame 402, right frame 403, left frame 404, and center shelf 405 are each made by joining multiple frame members. The fixing frame 400 is made by assembling and welding the bottom frame 401, rear frame 402, right frame 403, left frame 404, and center shelf 405 together. When welding the bottom frame 401, rear frame 402, right frame 403, left frame 404, and center shelf 405, lap welding using laser welding is preferred for the same reasons as welding frame members together. In particular, welding using the joining method of this embodiment described above is preferred. Before the joining process by welding, temporary support is required to maintain appropriate gaps between the frames.

[0052] (Temporary support for frame welding) Fig. 12 is a configuration diagram of the fixing frame 400 with each frame temporarily supported. Fig. 13 is an enlarged view of part B in Fig. 12. Conventionally, each frame is temporarily supported using a jig (temporary support jig) for temporarily supporting the bottom frame 401, rear frame 402, right frame 403, left frame 404, and center shelf plate 405. However, in this embodiment, the frames are fastened together with rivets 103, so the fixing frame 400 can stand on its own even before welding.

[0053] As shown in FIG. 13 , the bottom frame 401 has rivets 410 and joint points 411 used to join the bottom frame 401. Similarly, the right frame 403 has rivets 412 and joint points (not shown) used to join the right frame 403. To form the fixing frame 400, the bottom frame 401 and the right frame 403 are temporarily supported by multiple rivets 103, and the separation of the overlapping surfaces of the frames is restricted. The rear frame 402, the left frame 404, and the center shelf plate 405 are also temporarily supported by multiple rivets 103. Therefore, even before the fixing frame 400 is joined by welding, the overlapping surfaces near the welding joint points do not separate, and the fixing frame 400 is self-standing.

[0054] 14 is an explanatory diagram of the state in which the fixing frame 400 is mounted on the welding device before the joining process. The welding device is a laser welding device including a welding robot 810 and a rotary table 811. The fixing frame 400 to be welded is fixed to the rotary table 811. The welding robot 810 welds each frame of the fixing frame 400 fixed to the rotary table 811.

[0055] The fixing frame 400 has a bottom plate frame 401 directly fixed to the rotary table 811. Because the fixing frame 400 is self-supporting, the fixing frame 400 is fixed to the rotary table 811 by fixing the bottom plate frame 401, even if it is in a temporarily supported state.

[0056] In the frame structure of the inkjet recording apparatus 100 of this embodiment, the bottom plate frame 401 has a substantially flat shape, and therefore can be easily fixed to the rotary table 811. Furthermore, the shape of the fixing to the rotary table 811 can also be made common to the frame structures of each module of the inkjet recording apparatus 100. As a result, in the joining process of welding the frame structures of each module, there is no need to fix each temporary support jig to the rotary table 811, and it is possible to significantly reduce the man-hours required to replace the frame to be welded.

[0057] Figure 15 shows an enlarged view of part B in Figure 12 after joining (welding). Rivet 103 temporarily supports bottom frame 401 and right frame 403. Joint point 104 is located between 30 mm and 250 mm from the center of rivet 103, and welded. By setting joint point 104 between 30 mm and 250 mm from the center of rivet 103, elastic deformation of a portion of the steel plate during welding is possible, allowing zinc vapor generated between overlapping surfaces to be discharged. Furthermore, the gap between the two components (two frames) to be welded can be reduced to 0.4 mm or less.

[0058] As described above, in this embodiment, to create the frame body of the image forming apparatus, multiple frames are temporarily supported by joining members to make the frame body self-supporting, and then the frames are joined by laser welding at a position at least a predetermined distance from the joining position of the joining members. By setting the joining point by welding at a position at least a predetermined distance from the joining position, when plating metal vapor is generated, at least one of the frames undergoes slight deformation due to elastic deformation, and the plating metal vapor is then discharged from gap 109. This prevents the generation of blowholes and other problems caused by plating metal vapor, and reduces deterioration of welding quality.

[0059] As described above, the joining method of this embodiment does not require the frame members to have a stepped shape to allow the vapor of the plated metal to escape, as in the conventional method. Furthermore, it is not necessary to use a jig that can secure an air passage as a temporary support before the joining process by welding, or to perform a preliminary process such as removing zinc from the surface of the steel sheet by irradiating it with a laser before the actual welding. This significantly reduces costs and man-hours compared to the conventional method, enabling welding that suppresses deterioration in weld quality.

[0060] For reference, a conventional joining method will be described. Fig. 16 is an explanatory diagram of a conventional temporary support jig for frame welding. A conventional temporary support jig 800 for frame welding includes a bottom plate support portion 801, a rear support portion 802, a right support portion 803, and a left support portion 804. Each of these support portions is separable and includes a plurality of frame pressing members 805. The bottom plate support portion 801 temporarily supports the bottom plate frame 401 with the plurality of frame pressing members 805. The rear support portion 802 temporarily supports the rear frame 402 with the plurality of frame pressing members 805. The right support portion 803 temporarily supports the right frame 403 with the plurality of frame pressing members 805. The left support portion 804 temporarily supports the left frame 404 with the plurality of frame pressing members 805.

[0061] FIG. 17 is an explanatory diagram of a conventional frame joining method. The first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 that constitute the frame are pressed by a frame pressing member 805 to prevent separation ( FIG. 17( a)). The frame pressing member 805 biases a pressing portion 807 in the opposite direction to the support portion 806 using a pressing spring 808, thereby preventing separation between the steel sheets. The clearance between the pressing portion 807 and the frame receiving surface 809 is set to be smaller than the sum of the thicknesses of the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102. Therefore, the pressing portion 807 presses the frame receiving surface 809 to prevent the two steel sheets from separating. The laser light 107 is irradiated near the frame pressing member 805. The gap between the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 is configured to be 0.4 mm or less.

[0062] A molten pool 108 is formed on the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102 by the laser beam 107 (FIG. 17(b)). Zinc vapor generated between the steel sheets pushes up the first zinc-plated steel sheet 101, causing the compression spring 808 to contract slightly. The compression of the compression spring 808 creates a gap 109 between the first zinc-plated steel sheet 101 and the second zinc-plated steel sheet 102. The zinc vapor is discharged from the gap 109 as exhaust gas 110. When welding with the laser beam 107 is completed, a protrusion 111 is formed on the second zinc-plated steel sheet 102 as a laser welding mark (FIG. 17(c)).

[0063] FIG. 18 is an explanatory diagram of the temporary support jig 800 with each frame supported inside. Structurally, the temporary support jig 800 for frame welding is configured to cover the frame, and therefore the temporary support jig 800 for frame welding is large-scale. FIG. 19 is an explanatory diagram of the temporary support jig 800 mounted on a welding device. When welding the fixed frame 400, the temporary support jig 800 is mounted on a rotary table 811 so that welding can be performed from multiple directions. Because the temporary support jig 800 for frame welding is a large jig, the welding robot 810 and rotary table 811 also need to be large.

[0064] The inkjet recording apparatus 100 requires seven different types of frame bodies with different configurations. Therefore, a temporary support jig 800 for welding the frame bodies is required for each. Furthermore, since the temporary support jigs 800 for welding the large-scale frame bodies must be sequentially mounted on a welding device and welded, the number of steps in the welding joining process is large. By applying the joining method of this embodiment, such conventional temporary support jigs 800 are no longer necessary, and the number of steps in the welding process can be significantly reduced compared to conventional methods.

Claims

1. A joining method for joining a first metal plate and a second metal plate, comprising: a fastening step of fastening the overlapping first metal plate and the overlapping second metal plate with a fastening member at a fastening position; a welding step of welding the overlapping first metal plate and the overlapping second metal plate at a welding position, The distance between the fastening position and the welding position in a direction intersecting the thickness direction of the first metal sheet or the second metal sheet is a distance at which steam generated between the first metal sheet and the second metal sheet during the welding process elastically deforms at least one of the first metal sheet and the second metal sheet, thereby generating a gap between the first metal sheet and the second metal sheet. Joining method.

2. Each of the first metal plate and the second metal plate is The base metal and a coating material having a boiling point lower than the melting point of the base metal and coating the base metal, The joining method according to claim 1.

3. The gap does not exceed 0.4 mm during the welding process. The joining method according to claim 1 or 2.

4. The distance is 9.3 times or more the thickness of the first metal plate or the second metal plate, whichever has a larger deflection amount due to the elastic deformation. The joining method according to claim 1 or 2.

5. The thickness of the first metal plate and the second metal plate is 0.8 to 3.2 mm. The joining method according to claim 4.

6. The distance is 30 mm or more. The joining method according to claim 1 or 2.

7. The distance is 250 mm or less. The joining method according to claim 1 or 2.

8. The fastening member is a rivet. The joining method according to claim 1.

9. A joining method for joining a first metal plate and a second metal plate, comprising: a fastening step of fastening the overlapping first metal plate and the overlapping second metal plate with a fastening member at a fastening position; a welding step of welding the overlapping first metal plate and the overlapping second metal plate at a welding position, The distance between the fastening position and the welding position in a direction intersecting the thickness direction of the first metal plate or the second metal plate is 30 mm or more. Joining method.

10. Each of the first metal plate and the second metal plate is The base metal and a coating material having a boiling point lower than the melting point of the base metal and coating the base metal, The joining method according to claim 9.

11. steam generated between the first metal plate and the second metal plate during the welding process elastically deforms at least one of the first metal plate and the second metal plate, thereby creating a gap between the first metal plate and the second metal plate; The gap does not exceed 0.4 mm during the welding process. The joining method according to claim 9.

12. The distance is 9.3 times or more the thickness of the first metal plate or the second metal plate, whichever has a larger deflection amount due to the elastic deformation. The joining method according to claim 11.

13. The thickness of the first metal plate and the second metal plate is 0.8 to 3.2 mm. The joining method according to claim 11.

14. The distance is 250 mm or less. The joining method according to claim 9.

15. The fastening member is a rivet. The joining method according to claim 9.

16. an image forming unit; a frame body including a first metal plate and a second metal plate joined together and supporting the image forming unit; the first metal plate and the second metal plate are fastened together by a fastening member at a fastening position, the first metal plate and the second metal plate are welded at a welding position, The distance between the fastening position and the welding position in a direction intersecting the thickness direction of the first metal plate or the second metal plate is 30 mm or more. Image forming device.

17. Each of the first metal plate and the second metal plate includes a base metal and a coating material that has a boiling point lower than the melting point of the base metal and coats the base metal.

17. The image forming apparatus according to claim 16.

18. The thickness of the first metal plate and the second metal plate is 0.8 to 3.2 mm.

17. The image forming apparatus according to claim 16.

19. The distance is 250 mm or less.

17. The image forming apparatus according to claim 16.

Images