JP7532080B2 - Welding method - Google Patents

Description

The present invention relates to a welding method, and in particular to a technique for joining dissimilar metals.

The sheet metal used in the housing of the device to which power is supplied from an AC line (hereinafter referred to as the housing sheet metal) is electrically fastened via the earth terminal of the inlet provided in the device and the inlet sheet metal. The reason for this configuration is to satisfy electrical performance such as a shielding effect for shielding radiated noise from an electric board provided inside the device. Figures 12(a) and 12(b) are diagrams explaining the configuration of the inlet. (a) is a diagram seen from the direction in which the power cable is inserted into the inlet, and (b) is a diagram seen from the opposite side of (a). The inlet has inlet terminals 1 and 2 to which current is supplied from an AC power source, and an earth terminal 3 for connecting the frame, which is the ground (hereinafter referred to as GND) of the device, to the earth. The inlet also has a molded part 4 for fixing the inlet terminals 1 and 2 and the earth terminal 3. In addition, iron is widely used for the housing sheet metal and the inlet sheet metal because it is inexpensive, easy to process, easily available, and has a relatively low electrical conductivity. On the other hand, since the earth terminal 3 is assumed to carry electric current, it must have low electrical conductivity, and copper is widely used because it is easy to obtain and inexpensive. When fastening the earth terminal 3 to the inlet metal plate, metal welding is less expensive than fastening with screws (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).

For example, the following method can be considered for joining dissimilar metals. First, as shown in FIG. 12(c), the earth terminal 3 provided on the inlet is sandwiched between the inlet metal sheet 28. Then, the inlet metal sheet 28 is sandwiched between the first electrode 7 and the second electrode 8 for welding, and current is passed through the first electrode 7 and the second electrode 8 while they are under pressure from each other. This is a welding method in which the earth terminal 3 and the inlet metal sheet 28 are joined by melting them.

Patent No. 3311061 Patent No. 5723992 Special table 2016-523718 publication

However, because pressure is applied to copper, which is softer than iron, sandwiched between iron, there are the following problems. Figure 13 is a diagram explaining the problems, and shows the welded part of Figure 12(c) rotated 90 degrees to the left and enlarged. (a) shows the state before welding, and (b) shows the state after welding. When pressure is applied between the first electrode 7 and the second electrode 8 in the direction of the arrow 9 and a current is passed through it, the earth terminal 3 softens and collapses. Meanwhile, a reaction force 10 is generated in the inlet metal plate 28. Then, due to the reaction force 10, the inlet metal plate 28 is bent inward (toward the earth terminal 3) starting from point A, which is the contact point with the first electrode 7 and the second electrode 8. Also, the angle of bending of the bent part is larger on the right side (where the inlet metal plate 28 is continuous) than on the left side (where the inlet metal plate 28 is open), as shown in (b). This is because on the right side, there is a bent portion of the inlet metal sheet 28, so even if the earth terminal 3 is crushed, the position of the bent portion is less likely to change. On the other hand, the left side is the end of the earth terminal 3, so no external force acts to fix its position. Therefore, the right side is more likely to bend than the left side. In this way, bending occurs at point A, and the opposite surface warps outward (towards the electrode). Although the bending angle differs between the left and right sides, cracks 11 will occur in either case.

The inlet is subject to mechanical stress when the user inserts a power cable, or due to vibrations during transportation when installed in a product, so the inlet metal plate and earth terminal are required to have strong mechanical strength. However, if crack 11 occurs as described in Figure 13, sufficient mechanical strength may not be ensured, and electrical conductivity may be reduced.

The present invention was made under these circumstances, and aims to ensure the mechanical strength of the inlet and prevent a decrease in electrical conductivity.

In order to solve the above problems, the present invention has the following configuration.

(1) A welding method for welding an earth terminal formed of a first metal material and having a first surface and a second surface opposite to the first surface, to a first inlet metal sheet and a second inlet metal sheet formed of a second metal material different from the first metal material, the method comprising the steps of: bringing the first inlet metal sheet into contact with the first surface of the earth terminal, and bringing the second inlet metal sheet into contact with the second surface of the earth terminal, while bringing a first electrode into contact with a flat surface of the first inlet metal sheet and a second electrode into contact with a flat surface of the second inlet metal sheet, and applying a force between the first electrode and the second electrode to pass a current between the first electrode and the first inlet metal sheet ; a first region is a region where the first inlet metal sheet and the first surface of the earth terminal are in contact with each other, and a second region is a region where the first inlet metal sheet and the first surface of the earth terminal are in contact with each other, the entire second region is located inside an outer edge of the first region when viewed from the first electrode side , and a third region is a region where the second electrode and the flat surface of the second inlet metal sheet and the second surface of the earth terminal are in contact with each other, the entire fourth region is located inside an outer edge of the third region when viewed from the second electrode side, and the second region and the fourth region overlap when viewed from the first electrode side .

The present invention ensures the mechanical strength of the inlet and prevents a decrease in electrical conductivity.

FIG. 1 is a diagram illustrating the configuration of an inlet metal plate and a ground terminal according to the first embodiment. FIG. 1 is a diagram for explaining a mechanism for solving the problem in the first embodiment. FIG. 11 is a diagram illustrating the configuration of an inlet metal plate and a ground terminal according to the second embodiment. FIG. 1 is a diagram for explaining a mechanism for solving the problem in the second embodiment. FIG. 11 is a diagram illustrating the configuration of an inlet metal plate and a ground terminal according to the third embodiment. FIG. 10 is a diagram for explaining a mechanism for solving the problem of the third embodiment. FIG. 13 is a diagram illustrating the configuration of an inlet metal plate and a ground terminal according to the fourth embodiment. FIG. 13 is a diagram for explaining a specific configuration of the fourth embodiment. FIG. 13 is a diagram illustrating the configuration of an inlet metal plate and a ground terminal according to a fifth embodiment. FIG. 13 is a diagram illustrating the configuration of an inlet metal plate and a ground terminal according to the sixth embodiment. FIG. 13 is a diagram showing a configuration of an image forming apparatus according to a seventh embodiment of the present invention; FIG. 1 is a diagram for explaining the configuration of an inlet in a conventional example; FIG. 2 is a diagram for explaining a dissimilar metal welding configuration; A diagram explaining problems that occur when welding dissimilar metals in a conventional example.

The following describes in detail the embodiments of the present invention with reference to the drawings.

[Configuration of inlet metal plate and ground terminal]
FIG. 1 is a diagram for explaining a configuration for preventing cracks occurring when welding the inlet metal plate and the ground terminal in the first embodiment. The ground terminal is formed of copper, which is a first metal material, and the inlet metal plate is formed of iron, which is a second metal material different from the first metal material. The melting point of copper is lower than that of iron. In the first embodiment, the configuration of the inlet is the same as that in FIG. 12(a) and (b), and the same reference numerals are used for each part. In addition, the state when the ground terminal 3 and the inlet metal plate 28 are welded is the same as that in FIG. 12(c), and the same reference numerals are used for each part. Furthermore, the overlap configuration between each metal in the welded portion is the same as the configuration described in FIG. 13. FIG. 1(a) is a projection view depicting the welded portion from an oblique angle. Here, the first electrode 7 is on the upper side, the second electrode 8 is on the lower side, and the first electrode 7, the first inlet metal plate 5, the ground terminal 3, the second inlet metal plate 6, and the second electrode 8 are overlapped in this order from top to bottom. Fig. 1(b) is a top view showing the projection of Fig. 1(a) in two dimensions, as seen from the first electrode 7 side, (c) is a side view showing the side of the ground terminal 3 (the right side of (a)), and (d) is a side view showing the tip side of the ground terminal 3 (the side opposite to the molded part 4) (the front side of (a)).

In the first embodiment, the inlet has a first inlet metal sheet 5 and a second inlet metal sheet 6. In FIG. 1, the first inlet metal sheet 5 and the second inlet metal sheet 6 are depicted as separate bodies, but as shown in FIG. 12, they may have a bent portion on the right side of the figure and be integrated via the bent portion. The first surface of the earth terminal 3 contacts the first inlet metal sheet 5, and the second surface opposite the first surface contacts the second inlet metal sheet 6.

The first region where the first electrode 7 and the first inlet metal plate 5 contact is contact region C 12 (hatched area). The second region where the first inlet metal plate 5 and the first surface of the earth terminal 3 contact is contact region D 13 (horizontal line area). Here, when viewed from the first electrode 7 side (first electrode side), that is, when viewed as in the top view of Figure 1 (b), contact region D 13 is included inside contact region C 12.

The contact area between the second inlet metal plate 6 arranged below the earth terminal 3 and the second electrode 8 is also configured in the same way. That is, the third area where the second electrode 8 and the second inlet metal plate 6 contact is the contact area E 14 (hatched area). The fourth area where the second inlet metal plate 6 and the second surface of the earth terminal 3 contact is the contact area F 15 (horizontal line area). Here, when viewed from the second electrode 8 side (second electrode side), the contact area F 15 is included inside the contact area E 14. In the conventional example shown in FIG. 13, the contact area between the earth terminal 3 and the inlet metal plate 28 protrudes from the contact area between the electrode (7 or 8) and the inlet metal plate 28 in both electrodes, which is the opposite relationship to that in Example 1.

[Why cracks are prevented]
The mechanism of the first embodiment that prevents the occurrence of the crack 11 described in the conventional example will be described. FIG. 2 shows the state when the welding operation is performed in the side view of FIG. 1(d). As described in FIG. 13 of the conventional example, when pressure is applied to the first electrode 7 and the second electrode 8 in the direction of the arrow 9 and a current is passed through them (welding process), the earth terminal 3 softens and collapses. Then, reaction forces 10 are generated in the direction of the first inlet metal plate 5 and in the direction of the second inlet metal plate 6, respectively. In the first embodiment, since the contact area D 13 is included in the contact area C 12, even if the reaction force 10 is generated in the direction of the first inlet metal plate 5, the reaction force 10 can be received by the first inlet metal plate 5 in contact with the first electrode 7. Therefore, the first inlet metal plate 5 is not distorted and no cracks are generated. Similarly, since the contact area F 15 is included in the contact area E 14 below the ground terminal 3, even if a reaction force 10 occurs in the direction of the second inlet metal sheet 6, the reaction force 10 can be received by the second inlet metal sheet 6 in contact with the second electrode 8. Therefore, the second inlet metal sheet 6 does not warp and does not crack. As described above, in the first embodiment, an area sufficient to receive the reaction force 10 is secured in each of the contact area between the first electrode 7 and the first inlet metal sheet 5 and the contact area between the second electrode 8 and the second inlet metal sheet 6.

As described above, according to the first embodiment, it is possible to ensure the mechanical strength of the inlet and prevent a decrease in electrical conductivity.

[Configuration of inlet metal plate and ground terminal]
A configuration different from that of the first embodiment, in which cracks do not occur in the inlet metal plate, will be described. In the second embodiment, too, the contact area between the first electrode 7 and the first inlet metal plate 5 and the contact area between the second electrode 8 and the second inlet metal plate 6 are secured to receive the reaction force 10. FIG. 3 is a diagram for explaining the welding configuration of the second embodiment. In the second embodiment, the overlapping configuration between the metals in the welded portion is the same as that described in FIG. 13 and the like, and the same configuration as that already described is given the same reference numerals and the description will be omitted. FIG. 3(a) is a projection drawing depicting the welded portion from an oblique angle. FIG. 3(b) is a top view of the projection drawing of FIG. 3(a) shown in two dimensions as seen from the first electrode 7 side, FIG. 3(c) is a side view as seen from the side of the earth terminal 3, and FIG. 3(d) is a side view as seen from the tip of the earth terminal 3. In the second embodiment, too, the overlapping order of the two electrodes, the earth terminal, and the inlet metal plate is the same as that of the first embodiment. Further, the contact area C 12 between the first electrode 7 and the first inlet metal sheet 5 and the contact area E 14 between the second electrode 8 and the second inlet metal sheet 6 are also similar to those in the first embodiment.

Here, in the second embodiment, a first protrusion 16 protruding from the first inlet metal sheet 5 is provided on the surface of the first inlet metal sheet 5 opposite the contact area C 12, i.e., on the first surface side of the earth terminal 3. Also, a second protrusion 17 protruding from the second inlet metal sheet 6 is provided on the surface of the second inlet metal sheet 6 opposite the contact area E 14, i.e., on the second surface side of the earth terminal 3. In the second embodiment, the first protrusion 16 of the first inlet metal sheet 5 contacts the first surface of the earth terminal 3, and the second protrusion 17 of the second inlet metal sheet 6 contacts the second surface of the earth terminal 3. If the contact area between the first protrusion 16 and the earth terminal 3 is the contact area 16S, the contact area 16S is included in the contact area C 12 when viewed from the first electrode 7 side. In addition, if the contact area between the second protrusion 17 and the earth terminal 3 is the contact area 17S, the contact area 17S is included in the contact area E14 when viewed from the second electrode 8 side. The first protrusion 16 may be provided on the first inlet metal plate 5 so as to be included in the contact area C12, and is preferably disposed in the center of the contact area C12. The second protrusion 17 may be provided on the second inlet metal plate 6 so as to be included in the contact area E14, and is preferably disposed in the center of the contact area E14. In addition, the first protrusion 16 and the second protrusion 17 are preferably disposed so as to face each other across the earth terminal 3.

[Why cracks are prevented]
Next, a mechanism for preventing the occurrence of the cracks 11 described in the conventional example will be described. FIG. 4 shows a state when a welding operation is performed in the side view of FIG. 3(d). When pressure is applied to the first electrode 7 and the second electrode 8 in the direction of the arrow 9 and a current is passed through them, the earth terminal 3 softens and collapses. Then, a reaction force 10 is generated in the direction of the first inlet sheet metal 5 and the direction of the second inlet sheet metal 6, respectively. In the second embodiment, unlike the conventional example, the reaction force 10 is generated in the first inlet sheet metal 5 and the second inlet sheet metal 6 through the first protrusion 16 and the second protrusion 17, respectively. In the first inlet sheet metal 5, the first electrode 7 is present on the surface opposite to the first protrusion 16, and in the second inlet sheet metal 6, the second electrode is present on the surface opposite to the second protrusion 17. Therefore, the first inlet sheet metal 5 and the second inlet sheet metal 6 are not distorted by the reaction force 10, and no cracks are generated.

As described above, according to the second embodiment, it is possible to ensure the mechanical strength of the inlet and prevent a decrease in electrical conductivity.

[Configuration of inlet metal plate and ground terminal]
A configuration in which cracks do not occur in the inlet metal sheet, which is different from that in the first and second embodiments, will be described. In the third embodiment, the contact area between the first electrode 7 and the first inlet metal sheet 5 and the contact area between the second electrode 8 and the second inlet metal sheet 6 are also provided with an area large enough to receive the reaction force 10. FIG. 5 is a diagram for explaining the welding configuration in the third embodiment. FIG. 5(a) is a projection drawing of the welded portion from an oblique angle. FIG. 5(b) is a top view of the projection drawing in FIG. 5(a) as viewed from the first electrode 7 side, (c) is a side view as viewed from the side of the earth terminal 3, and (d) is a side view as viewed from the tip side of the earth terminal 3. In the third embodiment, the earth terminal 3 has a third protrusion 18 protruding from the earth terminal 3 toward the first inlet metal sheet 5 (first inlet metal sheet side) instead of the first protrusion 16 described in the second embodiment. Moreover, the ground terminal 3 has a fourth protrusion 19 protruding from the ground terminal 3 toward the second inlet metal sheet 6 (toward the second inlet metal sheet 6) instead of the second protrusion 17. In the third embodiment, the third protrusion 18 of the ground terminal 3 contacts the surface of the first inlet metal sheet 5 opposite to the surface in contact with the first electrode 7, and the fourth protrusion 19 of the ground terminal 3 contacts the surface of the second inlet metal sheet 6 opposite to the surface in contact with the second electrode 8. If the contact area between the third protrusion 18 and the first inlet metal sheet 5 is called a contact area 18S, the contact area 18S is included in the contact area C 12 when viewed from the first electrode 7 side. If the contact area between the fourth protrusion 19 and the second inlet metal sheet 6 is called a contact area 19S, the contact area 19S is included in the contact area E 14 when viewed from the second electrode 8 side. The third protrusion 18 may be provided on the ground terminal 3 so as to be included within the contact area C 12, and is preferably disposed in the center of the contact area C 12. The fourth protrusion 19 may be provided on the ground terminal 3 so as to be included within the contact area E 14, and is preferably disposed in the center of the contact area E 14. Preferably, the third protrusion 18 and the fourth protrusion 19 are disposed symmetrically with respect to the ground terminal 3.

[Why cracks are prevented]
Next, the mechanism for preventing the occurrence of cracks described in the conventional example will be described. Fig. 6 shows the state when the welding operation is performed in the side view of Fig. 5(b). When pressure is applied to the first electrode 7 and the second electrode 8 in the direction of the arrow 9 and a current is passed through them, the earth terminal 3 softens and collapses. The third protrusion 18 and the fourth protrusion 19 of the earth terminal 3 collapse along the first inlet metal sheet 5 and the second inlet metal sheet 6 as shown in Fig. 6. Then, reaction forces 10 are generated in the directions of the first inlet metal sheet 5 and the second inlet metal sheet 6, respectively. In the third embodiment, unlike the conventional example, the reaction force 10 is generated, but the first electrode 7 is present on the surface of the first inlet metal sheet 5 opposite to the third protrusion 18, and the second electrode 8 is present on the surface of the second inlet metal sheet 6 opposite to the fourth protrusion 19. Therefore, the first inlet metal sheet 5 and the second inlet metal sheet 6 are not distorted by the reaction force 10, and no cracks are generated. In other words, as in the first embodiment, the first electrode 7 and the second electrode 8 that receive the reaction force 10 are present on the opposing surfaces where the reaction force 10 is generated, and thus cracks in the first inlet metal sheet 5 and the second inlet metal sheet 6 are prevented.

As described above, according to the third embodiment, it is possible to ensure the mechanical strength of the inlet and prevent a decrease in electrical conductivity.

As explained in Examples 1, 2, and 3, in order to prevent cracks, the reaction force 10 generated during welding of the first inlet metal sheet 5 and the second inlet metal sheet 6 must be received by the first electrode 7 and the second electrode 8. In addition, the first protrusion 16 and the third protrusion 18 in Examples 2 and 3 are preferably disposed in the center of the contact area C 12, and the second protrusion 17 and the fourth protrusion 19 are preferably disposed in the center of the contact area D 13. This is because a stable pressure can be applied during welding. Therefore, in Example 4, a method for accurately welding the above-mentioned locations is proposed.

[Configuration of inlet metal plate and ground terminal]
7 is a diagram for explaining the welding configuration in Example 4. Also, FIG. 7(a) is a projection drawing depicting the welded portion from an oblique angle. FIG. 7(b) is a top view seen from the first electrode 7 side, showing the projection drawing in FIG. 7(a) in two dimensions, (c) is a side view seen from the side of the ground terminal 3, and (d) is a side view seen from the tip side of the ground terminal 3. In Example 4, the first inlet metal sheet 5 has a first recess 22 on the first electrode 7 side, and the first electrode 7 has a fifth protrusion 20 so as to enter the first recess 22. On the other hand, the second inlet metal sheet 6 has a second recess 24 on the second electrode 8 side, and the second electrode 8 has a sixth protrusion 21 so as to enter the second recess 24.

The first inlet metal plate 5 has a first protrusion 16 on the ground terminal 3 side as in Example 2, and the ground terminal 3 has a third recess 23 into which the first protrusion 16 fits. On the other hand, the second inlet metal plate 6 has a second protrusion 17 on the ground terminal 3 side as in Example 2, and the ground terminal 3 has a fourth recess 25 into which the second protrusion 17 fits. When viewed from the first electrode 7 or the second electrode 8, the fifth protrusion 20 and the first protrusion 16 or the sixth protrusion 21 and the second protrusion 17 are included in the contact area C 12 or the contact area E 14, respectively. Note that the fifth protrusion 20, the first protrusion 16, the second protrusion 17, and the sixth protrusion 21 may be recesses, and the first recess 22, the third recess 23, the fourth recess 25, and the second recess 24 may be protrusions.

In this way, the first electrode 7 and the first inlet metal plate 5, the first inlet metal plate 5 and the earth terminal 3, the earth terminal 3 and the second inlet metal plate 6, and the inlet metal plate 6 and the second electrode 8 are configured so that they do not shift from each other. When pressure welding is performed with the configuration described above, the welding point is positioned at the center where pressure is applied, so the welding surface is stable and welding with improved mechanical strength and conductivity is possible. As for cracks during welding, they do not occur because it is the same as the configuration in which protrusions are provided on the first inlet metal plate 5 and the second inlet metal plate 6 as described in Example 2.

[Method of Processing the First Inlet Metal Sheet 5 and the Second Inlet Metal Sheet 6]
Next, a specific processing method of the fourth embodiment will be described. FIG. 8 is a diagram for explaining a processing method of the first inlet metal plate 5 and the second inlet metal plate 6. FIG. 8(a) is a diagram showing a state in which the first inlet metal plate 5 and the second inlet metal plate 6 are an integral metal plate. Since the material of the first inlet metal plate 5 and the second inlet metal plate 6 is iron, it is difficult to process them with a router, and processing such as extrusion with a mold, bending, and cutting is performed. First, the first protrusion 16, the second protrusion 17, the first recess 22, and the third recess 24 are formed on an iron plate 56 cut to a predetermined size by, for example, extrusion with a mold. Then, as shown in FIG. 8(b), the integral iron plate 56 is bent in the direction of the arrow 26 shown in FIG. 8(a) so that the first protrusion 16 and the second protrusion 17 are opposed to each other. As a result, a bent portion 27 is formed on the iron plate 56. Next, as shown in FIG. 8( c ), the bent portion 27 of the iron plate 56 is cut off, and one of the remaining iron plates 56 is formed as the first inlet metal sheet 5 , and the other is formed as the second inlet metal sheet 6 .

[How to process the earth terminal]
Next, the processing of the earth terminal 3 will be described. Since the processing is easy, the drawings will be omitted. The earth terminal 3 is made of a copper material, which is relatively soft and easy to process. In addition, in the fourth embodiment, the third recess 23 and the fourth recess 25 are formed at the same positions on the top and bottom, so that the earth terminal 3 has a thickness of about several mm. Therefore, the third recess 23 and the fourth recess 25 are formed by a router such as a drill. As described above, the earth terminal 3, the first inlet metal plate 5, and the second inlet metal plate 6 are processed, overlapped in the order shown in FIG. 7, and positioned by fitting each protrusion into each recess, and then welded.

In FIG. 8(c), the bent portion 27 of the iron plate 56 is cut off from the iron plate 56, but in the welding process, a momentary large current is passed, so welding can be performed without cutting off the iron plate 56. Also, in the first to fourth embodiments, a configuration that is symmetrical above and below the earth terminal 3 has been described, but the problems of the present invention can be solved and electrical continuity and mechanical strength can be ensured with any combination of the above and below configurations in all the embodiments.

As described above, according to Example 4, it is possible to ensure the mechanical strength of the inlet and prevent a decrease in electrical conductivity.

[Configuration of inlet metal plate and ground terminal]
FIG. 9 is a diagram for explaining the welding configuration in Example 5. In Example 5, the overlapping configuration between the metals in the welded portion is the same as that described in FIG. 13, and the same reference numerals are used and the description is omitted. FIG. 9(a) is a projection drawing depicting the welded portion from an oblique angle. FIG. 9(b) is a top view of the projection drawing in FIG. 9(a) shown in two dimensions as seen from the first electrode 7 side, FIG. 9(c) is a side view as seen from the side of the earth terminal 3, and FIG. 9(d) is a side view as seen from the tip side of the earth terminal 3. In Example 5, the overlapping order of the first electrode 7, the second electrode 8, the earth terminal 3, the first inlet metal plate 5, and the second inlet metal plate 6 is the same as in Example 1. In Example 5, the first recess 22 is provided in the first inlet metal plate 5, and the second recess 24 is added to the second inlet metal plate 6 in FIG. 3 of Example 2. In this case, the first protrusion 16 and the first recess 22, and the second protrusion 17 and the second recess 24 can be formed by the extrusion process described in Fig. 8 of Example 4. Also, cracks in the first inlet metal sheet 5 and the second inlet metal sheet 6 are prevented in the same manner as in the above-mentioned examples.

As described above, according to Example 5, it is possible to ensure the mechanical strength of the inlet and prevent a decrease in electrical conductivity.

[Configuration of inlet metal plate and ground terminal]
FIG. 10 is a diagram for explaining the welding configuration in Example 6, and the same reference numerals are used for the same configurations as those explained in the above-mentioned examples, and the explanation is omitted. In Example 6, the overlap configuration between the metals in the welded portion is the same as that explained in FIG. 13. FIG. 10(a) is a projection drawing depicting the welded portion from an oblique angle. FIG. 10(b) is a top view of the projection drawing in FIG. 10(a) shown in two dimensions as seen from the first electrode 7 side, (c) is a side view as seen from the side of the earth terminal 3, and (d) is a side view as seen from the tip side of the earth terminal 3. In Example 6, the overlap order of the first electrode 7, the second electrode 8, the earth terminal 3, the first inlet metal plate 5, and the second inlet metal plate 6 is the same as in Example 1. In Example 6, the second protrusion 17, the sixth protrusion 21, the second recess 24, and the fourth recess 25 are not provided in FIG. 7 of Example 4. That is, in the sixth embodiment, no protrusions or recesses are provided on the second inlet metal plate 6 and the second surface of the earth terminal. It is also possible to provide no protrusions or recesses on the first inlet metal plate 5 side and the second inlet metal plate 6 side with protrusions or recesses similar to those in FIG. 7. Furthermore, the protrusions and recesses provided on both sides of the earth terminal 3 in FIG. 3 and FIG. 5 may be provided only on one side. Even in this configuration, the contact area between the first electrode 7 and the first inlet metal plate 5 and the contact area between the second electrode 8 and the second inlet metal plate 6 are each provided with an area large enough to receive the reaction force 10. This prevents the first inlet metal plate 5 and the second inlet metal plate 6 from cracking.

As described above, according to Example 6, it is possible to ensure the mechanical strength of the inlet and prevent a decrease in electrical conductivity.

[Explanation of Laser Beam Printer]
FIG. 11 shows a schematic configuration of a laser beam printer as an example of an image forming apparatus. The laser beam printer 1000 (hereinafter referred to as the printer 1000) includes a photosensitive drum 1010, a charging section 1020, and a developing section 1030. The photosensitive drum 1010 is an image carrier on which an electrostatic latent image is formed. The charging section 1020 uniformly charges the photosensitive drum 1010. The developing section 1030 forms a toner image by developing the electrostatic latent image formed on the photosensitive drum 1010 with toner. The toner image formed on the photosensitive drum 1010 (on the image carrier) is transferred by a transfer section 1050 to a sheet P as a recording material supplied from a cassette 1040, and the unfixed toner image transferred to the sheet P is fixed by a fixing device 1060 and discharged to a tray 1070. The photosensitive drum 1010, the charging section 1020, the developing section 1030, and the transfer section 1050 constitute an image forming section. The printer 1000 also includes a power supply device 1080, which supplies power to a drive unit such as a motor and to a control unit 5000. The printer 1000 includes a housing sheet metal 1007, an inlet sheet metal 1006 fastened to the housing sheet metal 1007 with screws 1008, and an inlet 1005 held by the inlet sheet metal 1006. AC power is supplied to the power supply device 1080 by fitting a power cord (not shown) into the inlet 1005. The control unit 5000 includes a CPU (not shown) and controls the image forming operation by the image forming unit, the conveying operation of the sheet P, and the like.

The inlet 1005 has an earth terminal, to which a first inlet metal sheet and a second inlet metal sheet are welded in the configurations of Examples 1 to 6. At least one of the first inlet metal sheet and the second inlet metal sheet is integrated with the inlet metal sheet 1006. Note that the image forming apparatus to which the inlet 1005 to which the welding method of the present invention is applied can be applied is not limited to the configuration exemplified in FIG. 11.

As described above, according to Example 7, it is possible to ensure the mechanical strength of the inlet and prevent a decrease in electrical conductivity.

3 Ground terminal 5 First inlet metal plate 6 Second inlet metal plate 7 First electrode 8 Second electrode 12 Contact area C
13 Contact area D
14 Contact area E
15 Contact area F

Claims (17)

A welding method for welding an earth terminal formed of a first metal material and having a first surface and a second surface opposite to the first surface, to a first inlet metal plate and a second inlet metal plate formed of a second metal material different from the first metal material, the method comprising the steps of:
a welding process of contacting the first inlet metal sheet with the first surface of the earth terminal and contacting the second inlet metal sheet with the second surface of the earth terminal, bringing a first electrode into contact with a flat surface of the first inlet metal sheet and a second electrode into contact with a flat surface of the second inlet metal sheet, and applying a force between the first electrode and the second electrode to pass a current therebetween,
When a region where the first electrode and the flat surface of the first inlet metal plate are in contact with each other is defined as a first region, and a region where the first inlet metal plate and the first surface of the ground terminal are in contact with each other is defined as a second region , the entire second region is located inside an outer edge of the first region when viewed from the first electrode side, and
a region where the second electrode and the flat surface of the second inlet metal plate are in contact with each other is defined as a third region, and a region where the second inlet metal plate and the second surface of the ground terminal are in contact with each other is defined as a fourth region , the entire fourth region is located inside an outer edge of the third region when viewed from the second electrode side,
When viewed from the first electrode side, the second region and the fourth region overlap with each other.
A welding method comprising the steps of: the first inlet metal plate has a first protrusion on the first surface side of the ground terminal,
the second inlet metal plate has a second protrusion on the second surface side of the ground terminal,
the second region is a region where the first protrusion contacts the ground terminal,
the fourth region is a region where the second protrusion contacts the ground terminal;
2. The welding method according to claim 1 . the first inlet metal plate has a first recess on the first electrode side,
The welding method according to claim 2 , wherein the second inlet metal sheet has a second recess on a side of the second electrode. the first electrode has a fifth protrusion that fits into the first recess;
The welding method according to claim 3 , wherein the second electrode has a sixth protrusion that fits into the second recess. the first electrode is spaced from an inner surface of the first recess in a state in which the first electrode is in contact with a periphery of the first recess,
The second electrode is spaced from an inner surface of the second recess in a state in which the second electrode is in contact with a periphery of the second recess.
4. The welding method according to claim 3. 6. The welding method according to claim 2, wherein the ground terminal has a third recess into which the first protrusion fits and a fourth recess into which the second protrusion fits. The welding method according to claim 1, characterized in that the ground terminal has a third protrusion on the first inlet metal sheet side and a fourth protrusion on the second inlet metal sheet side. the first inlet metal plate has a first protrusion on the first surface side of the ground terminal,
The second region is a region where the first protrusion contacts the ground terminal.
2. The welding method according to claim 1 . The welding method according to claim 8 , wherein the first inlet metal sheet has a first recess on a side of the first electrode. The method of claim 9 , wherein the first electrode has a fifth protrusion that fits into the first recess. The first electrode is spaced from an inner surface of the first recess in a state in which the first electrode is in contact with a periphery of the first recess.
10. The welding method according to claim 9. The welding method according to any one of claims 8 to 11 , wherein the ground terminal has a third recess into which the first protrusion fits. The welding method according to claim 1, characterized in that the ground terminal has a third protrusion on the first inlet sheet metal side. 14. The welding method according to claim 1, wherein the melting point of the first metallic material is lower than the melting point of the second metallic material. 15. The welding method according to claim 1, wherein the first metal material is copper and the second metal material is iron. 16. The welding method according to claim 1, wherein the first inlet metal sheet and the second inlet metal sheet are welded to the earth terminal in a state in which the first inlet metal sheet and the second inlet metal sheet are connected via a bent portion. When viewed from the first electrode side, the second region overlaps with a central portion of the first region, and when viewed from the second electrode side, the fourth region overlaps with a central portion of the third region.
The welding method according to any one of claims 1 to 16.

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