JP7618449B2 - Welding method - Google Patents

Description

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

Electronic devices such as image forming devices generally have an inlet, and AC power is supplied to the electronic device by fitting a power cord into the inlet. The housing sheet metal used in the housing of the electronic device is electrically connected to the earth terminal of the inlet provided on the electronic device in order to satisfy electrical performance. Here, electrical performance refers to, for example, a shielding effect for blocking radiated noise from an electric board provided inside the device. Iron is widely used for housing sheet metal because it is inexpensive, easy to process, easily available, and has a relatively low electrical conductivity. On the other hand, the earth terminal of the inlet is assumed to pass electric current, so it must have low electrical conductivity, and copper is widely used because it is easily available and inexpensive.

For example, the configurations shown in Patent Document 1 and Patent Document 2 are known as methods for electrically fastening the earth terminal of an inlet to the metal housing of an electronic device. Patent Document 1 describes a configuration in which the metal housing and the earth terminal of the inlet are fastened with a screw. Patent Document 2 describes a configuration in which the metal housing and the earth terminal of the inlet are fastened by soldering. Also, for example, Patent Document 3 describes a method for ensuring mechanical strength in the joining of dissimilar metals with significantly different melting points, such as aluminum and steel. That is, the method involves sandwiching a metal with a low melting point with a metal with a high melting point, applying pressure with an electrode and passing an electric current through it, which generates heat to melt the metal with the low melting point, and then bringing the metals with high melting points into contact with each other to weld them.

Furthermore, a conventional method for joining dissimilar metals has also been proposed, as shown in Figures 8 and 9. In this joining method, current is passed through the first electrode 20a and the second electrode 20b while the earth terminal 3 is sandwiched between the first part 10a and the second part 10b of the metal plate 10. This generates Joule heat due to the contact resistance at the interface between the earth terminal 3 and the first part 10a and the applied current, and the two are welded at the welded part 11a. Similarly, Joule heat is generated due to the contact resistance at the interface between the earth terminal 3 and the second part 10b and the applied current, and the two are welded at the welded part 11b.

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

However, in the conventional example, the earth terminal 3 is in contact with the first part 10a and the second part 10b, so that the contact resistance is small and a large current must be passed to obtain the amount of heat required for welding. In addition, because the heat generating area (hereinafter referred to as the heat generating area) is large, the heat is transferred to the molded part 4 attached to the earth terminal 3, and the molded part 4 may melt. Furthermore, when a current is passed through different metals to weld them with Joule heat, in addition to Joule heat, heat generation and absorption of heat occur at the junction due to the Peltier effect. When the earth terminal 3 is sandwiched between the first part 10a and the second part 10b and welding is performed at two junctions as in the conventional example, heat may be generated at one junction and absorption of heat may occur at the other junction due to the Peltier effect. In this case, there is a problem that the joint is unstable due to the loss of thermal balance, only one side of the surface peels off, and poor welding occurs. For this reason, it is required to reduce poor welding and improve productivity.

The present invention was made under these circumstances, and aims to reduce welding defects and improve productivity.

To solve the above problems, the present invention has the following configuration.

(1) A welding method comprising: a welding step of contacting a first electrode with the first member and a second electrode with the second member , with a third member made of a third metal and held by a mold member sandwiched between a first member made of a first metal and a second member made of a second metal, and applying a force toward the third member to each of the first electrode and the second electrode to pass a current therethrough; the first member has at least one first protrusion that protrudes toward the third member and contacts the third member , and/or the second member has at least one second protrusion that protrudes toward the third member and contacts the third member ; and in the welding step, the first member and the second member are separated from the mold member, and the first member and a first surface of the third member are joined, and the second member and a second surface of the third member opposite to the first surface are joined.
(2) A welding method comprising a welding step of contacting a first electrode with the first member and a second electrode with the second member, with a third member made of a third metal and held by a molding member sandwiched between a first member made of a first metal and a second member made of a second metal, and applying a force toward the third member to each of the first electrode and the second electrode to pass a current therethrough, wherein the third member has at least one first protrusion on a first surface that protrudes toward the first member and contacts the first member, and/or the third member has at least one second protrusion on a second surface opposite to the first surface that protrudes toward the second member and contacts the second member, and wherein in the welding step, the first member and the second member are separated from the molding member, and the first surface of the first member and the third member are joined, and the second surface of the second member and the third member are joined.

The present invention can reduce welding defects and improve productivity.

FIG. 1 is a diagram showing a configuration of a protruding portion of a metal plate according to a first embodiment; FIG. 1 is a diagram showing a configuration of a protruding portion of a metal plate according to a first embodiment; FIG. 13 is a diagram showing the configuration of a protruding portion of a metal plate according to a second embodiment; FIG. 13 is a diagram showing the configuration of a protruding portion of a metal plate according to a second embodiment; FIG. 13 is a diagram showing a configuration of an image forming apparatus as an electronic apparatus according to a fourth embodiment of the present invention; FIG. 13 shows the configuration of the inlet, the metal plate, and the substrate of the fourth embodiment. FIG. 13 is a diagram showing the configuration of a metal plate and a ground terminal according to a fourth embodiment of the present invention; A diagram showing the configuration of the inlet and sheet metal of a conventional example. A diagram showing a conventional welding process for dissimilar metals. FIG. 13 shows a configuration of a third embodiment. FIG. 13 shows a configuration of a third embodiment.

[Conventional welding method]
For comparison with the following embodiment, a conventional welding method for dissimilar metals will be described with reference to Figs. 8 and 9. Figs. 8(a) and 8(b) are diagrams for explaining the configuration of an inlet 5. Fig. 8(a) is a diagram seen from the direction in which a power cable (not shown) is inserted into the inlet 5, and Fig. 8(b) is a diagram seen from the opposite side of Fig. 8(a). The inlet 5 has inlet terminals 1 and 2, a ground terminal 3, and a molded part 4. The ground terminal 3 is a copper terminal. The inlet terminals 1 and 2 are terminals to which current is supplied from an AC power source (not shown). The ground terminal 3 is a terminal connected to a metal plate (hereinafter also referred to as a frame GND) that serves as the ground (hereinafter referred to as GND) of an electronic device. The molded part 4 is a member for fixing the inlet terminals 1 and 2 and the ground terminal 3.

Figure 8 (c) shows a configuration in which the inlet 5 and the sheet metal 10 of the electronic device are connected. The sheet metal 10 holds the molded part 4 of the inlet 5, and is configured to sandwich the earth terminal 3 between the first part 10a and the second part 10b. In other words, the first part 10a and the second part 10b can also be called the sheet metal sandwiching part. The sheet metal 10 is made of steel. Here, the sheet metal 10 has the first part 10a, the second part 10b, the part 10c, the part 10d, and the bent part 10e. The part 10d extends continuously from the part 10c toward the tip of the earth terminal 3 (the end opposite the molded part 4) while avoiding the inlet 5. The first part 10a is continuous with the part 10d and is in contact with the first surface 3a (hereinafter referred to as surface 3a) of the earth terminal 3. The second portion 10b is continuous with the first portion 10a via the bent portion 10e, and is in contact with the second surface 3b (hereinafter referred to as surface 3b) of the ground terminal 3 opposite surface 3a. In this way, the first portion 10a and the second portion 10b are integrally formed with the metal plate 10 (part 10c in detail). The metal plate 10 of the electronic device, specifically the first portion 10a and the second portion 10b, are arranged to sandwich the ground terminal 3 of the inlet 5. The ground terminal 3 is welded to the first portion 10a and the second portion 10b of the metal plate 10.

FIG. 9 is a cross-sectional view showing a procedure (welding process) for welding the earth terminal 3 to the first part 10a and the second part 10b. The bent part 10e is not shown. FIG. 9(a) shows the state before welding. The first electrode 20a and the second electrode 20b are both cylindrical electrodes with C-chamfered corners at the tip, and are members that pass current to the earth terminal 3, the first part 10a, and the second part 10b. FIG. 9(b) shows a state in which the earth terminal 3, the first part 10a, and the second part 10b are pressed by the first electrode 20a and the second electrode 20b in the direction of the arrow in FIG. 9(b). In the state of FIG. 9(b), a current is applied from the first electrode 20a to the second electrode 20b. The direction of the current may be reversed. 9(c) is a diagram showing a state in which the surface 3a of the earth terminal 3 is welded to the first portion 10a and the surface 3b of the earth terminal 3 is welded to the second portion 10b after current application. When current is applied to the first electrode 20a and the second electrode 20b, Joule heat is generated by the contact resistance and current at the interface between the surface 3a of the earth terminal 3 and the first portion 10a, and they are welded at the welded portion 11a. Similarly, Joule heat is generated by the contact resistance and current at the interface between the surface 3b of the earth terminal 3 and the second portion 10b, and they are welded at the welded portion 11b.
Although the above description has been given taking an example in which the earth terminal 3 is made of copper and the metal plate 10 is made of steel, they may be made of other dissimilar metals.

The dissimilar metal joining configuration of Example 1 will be described with reference to the drawings. In Example 1, a configuration for improving productivity by reducing the current value for obtaining the heat required for welding, and a configuration for preventing melting of a molded member attached to a metal material will be described. Note that the configuration of the inlet 5 is the same as that of Figures 8(a) and (b), and a description thereof will be omitted. Also, the configuration of the sheet metal provided in the electronic device (not shown) is the same as that of Figure 8(c). Note that in Example 1, the sheet metal is sheet metal 30. Figures 1 and 2 are diagrams explaining the configuration of the welded parts of the sheets 30, 32, 34, and 36 of Example 1 with the earth terminal 3.

[Sheet metal configuration]
The electronic device (not shown) includes an inlet 5 and a metal plate 30. The metal plate 30 has a first portion 30a, a second portion 30b, and a bent portion 30e. The metal plate 30 also has portions corresponding to the portions 10c and 10d described in FIG. 9, and the same applies to metal plates 32, 34, and 36 described below. The first portion 30a is a first member made of iron, which is a first metal, and the second portion 30b is a second member made of iron, which is a second metal. The earth terminal 3 is a third member made of copper, which is a third metal. The first portion 30a is a portion that contacts the surface 3a of the earth terminal 3. The second portion 30b is a portion that is continuous with the first portion 30a via the bent portion 30e and contacts the surface 3b of the earth terminal 3. A metal plate 30 of the electronic device, specifically a first portion 30a and a second portion 30b, is disposed so as to sandwich the ground terminal 3 of the inlet 5. The ground terminal 3 is welded to the first portion 30a and the second portion 30b of the metal plate 30.

In FIG. 1(a), the first and second parts 30a and 30b are provided with a first projection 31a and a second projection 31b, respectively, which are point-shaped projections protruding from the inner surface (the surface in contact with the earth terminal 3). By providing the projection 31a on the first part 30a and the projection 31b on the second part 30b, respectively, it is possible to generate the amount of heat required for welding with a smaller current value than in the conventional example in which no projections are provided. This is because the contact resistance of the interface between the surface 3a of the earth terminal 3 and the first part 30a, and the contact resistance of the interface between the surface 3b of the earth terminal 3 and the second part 30b are increased, respectively. This makes it possible to improve productivity. In addition, the heat generation area can be localized, and melting of the molded part 4 attached to the earth terminal 3 can be prevented.

In addition, although the protrusion 31a (or protrusion 31b) in FIG. 2(a) is conical, it may be of other shapes as long as it is in point contact with the surface 3a (or surface 3b) of the earth terminal 3 before welding. The position of the protrusion 31a is preferably provided in the approximate center of the area where the first electrode 20a contacts the first part 30a, but it may be located within the area where the first electrode 20a contacts the first part 30a. Similarly, the position of the protrusion 31b is preferably provided in the approximate center of the area where the second electrode 20b contacts the second part 30b, but it may be located within the area where the second electrode 20b contacts the second part 30b.

(Modifications of the shape of the protrusion)
FIG. 1B shows a configuration in which the shape of the protrusion has been changed. The sheet metal 32 has a first portion 32a, a second portion 32b, and a bent portion 32e. The first portion 32a is provided with a protrusion 33a, which is a linear first protrusion protruding from the inner surface side of the first portion 32a. The second portion 32b is provided with a linear protrusion 33b, which is a second protrusion, protruding from the inner surface side of the second portion 32b. Although the contact resistance is lower than that of the configuration of FIG. 1A and the current required for welding is increased, the joint strength can be increased by the increased joint area.

Although one protrusion 33a (or protrusion 33b) is provided on the first part 32a (or the second part 32b), the protrusion 33a (or protrusion 33b) may be divided into multiple parts. Also, multiple protrusions 33a (or protrusions 33b) may be provided on the first part 32a (or the second part 32b). Furthermore, although the protrusion 33a (or protrusion 33b) in FIG. 1(b) is semi-cylindrical, it may have another shape, and may have any shape that makes line contact with the surface 3a (or surface 3b) of the earth terminal 3 before welding. Also, the position of the protrusion 33a is preferably provided in the approximate center of the area where the first electrode 20a contacts the first part 32a, but it may be located within the area where the first electrode 20a contacts the first part 32a. Similarly, the position of the protrusion 33b is preferably provided approximately in the center of the area where the second electrode 20b contacts the second portion 32b, but it may be disposed within the area where the second electrode 20b contacts the second portion 32b.

Figure 2 shows a configuration in which the metal sheets 34, 36 do not have bent portions, and the first and second portions are separate. The first portion 34a in Figure 2(a) is provided with a point-shaped protrusion 35a that protrudes from the surface that contacts the earth terminal 3. The second portion 34b is provided with a point-shaped protrusion 35b that protrudes from the surface that contacts the earth terminal 3.

In addition, the first portion 36a in FIG. 2(b) is provided with a linear protrusion 37a that protrudes from the surface that contacts the earth terminal 3. The second portion 36b is provided with a linear protrusion 37b that protrudes from the surface that contacts the earth terminal 3. In FIG. 2, the amount of metal sheets 34 and 36 used and the processing costs can be further reduced.

As described above, by increasing the contact resistance between the earth terminal 3 and the first and second parts of the metal sheets 30, 32, 34, and 36, the current value required to obtain the heat required for welding can be reduced, improving productivity. Furthermore, by localizing the heat generation area, it is possible to prevent the molded member attached to the metal material from melting. In the first embodiment, a configuration in which protrusions are provided on the metal sheets 30, 32, 34, and 36 has been described, but a configuration in which protrusions are provided on the earth terminal 3 or on both the metal sheets and the earth terminal 3 can also be applied since they provide the same effect. It may also be applied to the inlet terminals 1 and 2 to which current is supplied from an AC power source.

As described above, according to Example 1, it is possible to reduce welding defects and improve productivity.

In the second embodiment, a configuration is described that allows stable welding even if the thermal balance is disturbed by the Peltier effect. Figures 3 and 4 are diagrams explaining the configuration of the first and second parts of the metal sheets 40, 42, 44, and 46 in the second embodiment.

[Sheet metal configuration]
3A, in the metal plate 40, the first portion 40a is connected to the second portion 40b via a bent portion 40e. The second portion 40b is provided with a point-shaped protrusion 41b that protrudes toward the inner surface (the surface that contacts the ground terminal 3) of the second portion 40b. On the other hand, the first portion 40a is not provided with a protrusion that protrudes toward the inner surface of the first portion 40a. The shape, number, position, etc. of the protrusion 41b are the same as those in the first embodiment.

This configuration results in a difference in contact resistance between the first portion 40a and the surface 3a of the earth terminal 3 and the contact resistance between the second portion 40b and the surface 3b of the earth terminal 3. Specifically, the contact resistance between the second portion 40b, which has the protrusion 41b, and the surface 3b of the earth terminal 3 is greater than the contact resistance between the first portion 40a, which does not have the protrusion, and the surface 3a of the earth terminal.

Therefore, the Joule heat generated when a current is applied is greater at the junction between the second portion 40b and the surface 3b of the earth terminal 3. Because the Peltier effect causes heat generation at one junction and heat absorption at the other, stable welding can be performed by making the Joule heat different so that the sum of heat absorption and generation due to the Peltier effect and heat generation due to Joule heat is equal. In other words, at the junction where heat generation occurs due to the Peltier effect, the first portion 40a is configured without protrusions so that Joule heat is reduced. On the other hand, at the junction where heat absorption occurs due to the Peltier effect, the second portion 40b is configured with protrusions 41b so that Joule heat is increased.

(Modification 1 of the shape of the protrusion)
Fig. 3(b) shows a configuration in which the protrusion is linear. In the sheet metal 42, the first portion 42a is connected to the second portion 42b via a bent portion 42e. The second portion 42b is provided with a linear protrusion 43b protruding toward the inner surface side of the second portion 42b. On the other hand, the first portion 42a is not provided with a protrusion protruding toward the inner surface side of the first portion 42a. With this configuration, as with the configuration of Fig. 3(a), the Joule heat generated during welding can be made different, and the same effect can be obtained.

(Modification 2 of the shape of the protrusion)
FIG. 4(a) shows a configuration in which the number of protrusions is changed. In the sheet metal 44, the first part 44a is connected to the second part 44b via a bent part 44e. The second part 44b is provided with one point-shaped protrusion 45b protruding toward the inner surface side of the second part 44b. On the other hand, the first part 44a is provided with two point-shaped protrusions, 45a and 45c, protruding toward the inner surface side of the first part 44a. At the junction where heat absorption occurs due to the Peltier effect, the number of protrusions is reduced so that Joule heat is increased (contact resistance is increased). On the other hand, at the junction where heat generation occurs due to the Peltier effect, the number of protrusions is increased so that Joule heat is reduced (contact resistance is reduced). In this way, the heat is balanced by the number of protrusions. With this configuration, the Joule heat generated during welding can be made different, as in the configuration of FIG. 3(a), and the same effect can be obtained. Here, the number of protrusions is not limited to a combination of one and two, and any combination of different numbers of protrusions can provide different contact resistances and similar effects.

(Modification 3 of the shape of the protrusion)
4B shows a configuration in which the shape of the protrusion has been changed. In the metal plate 46, the first portion 46a is connected to the second portion 46b via a bent portion 46e. The second portion 46b is provided with a point-shaped protrusion 47b that protrudes toward the inner surface of the second portion 46b. Meanwhile, the first portion 46a is provided with a linear protrusion 47a that protrudes toward the inner surface of the first portion 46a.

The point-shaped protrusion 47b contacts the surface 3b of the earth terminal 3 at a point, and the linear protrusion 47a contacts the surface 3a of the earth terminal 3 in a line. Therefore, the contact resistance between the first part 46a with the linear protrusion 47a and the surface 3a of the earth terminal 3 is smaller than the contact resistance between the second part 46b with the point-shaped protrusion 47b and the surface 3b of the earth terminal 3. At the junction where heat absorption occurs due to the Peltier effect, the protrusion is made point-shaped so that Joule heat is large, and at the junction where heat generation occurs due to the Peltier effect, the protrusion is made linear so that Joule heat is small. With this configuration, as with the configuration in FIG. 3(a), the Joule heat can be made different, and the same effect can be obtained.

As described above, by making the contact resistances of the two junctions between the earth terminal 3 and the first and second parts different, stable welding can be performed even if the thermal balance is disturbed by the Peltier effect. The above-mentioned configuration may also be provided on the earth terminal 3. As described above, according to Example 2, it is possible to reduce welding defects and improve productivity.

In the third embodiment, the cross-sectional area of the bent portion of the dissimilar metal joint member having a flat portion and a bent portion to be welded to the inlet earth terminal is made smaller than the cross-sectional area of the flat portion. Figure 10 is a diagram illustrating the configuration of the welded portion of the inlet metal sheet 10 in this embodiment.

60a and 60b are flat parts that sandwich the inlet earth terminal 3, and 60c is a bent part. 61 is a hole provided in the bent part 60c. S1 is the cross-sectional area of the bent part 60c, and S2 is the cross-sectional area of the flat parts 60a and 60b. By providing the hole 61, the cross-sectional area S1 is smaller than the cross-sectional area S2 (S1<S2), and the elastic force of the inlet metal plate 10 after welding can be reduced compared to the conventional configuration without a hole. In addition, the current I2 that does not contribute to welding that flows during welding increases the resistance value of the path by reducing the cross-sectional area S1 of the bent part 60c, and the current I2 can be reduced.

As described above, by adding a hole 61 to the bent portion 60c, the elastic force of the inlet metal sheet 10 after welding can be reduced and peeling of the welded portion can be prevented. In addition, the wasteful current I2 that does not contribute to welding can be reduced, improving productivity. In this embodiment, a configuration in which one hole is added to the bent portion 60 has been described, but a configuration in which multiple holes are provided can also provide the same effect, so a configuration in which multiple holes are provided is also possible.

As another configuration, FIG. 11 shows a configuration in which the cross-sectional area is reduced without providing a hole. In FIG. 11, 70a and 70b are flat portions that sandwich the inlet earth terminal 3, and 70c is a bent portion. W1 is the bending width of the bent portion 40c in a direction perpendicular to the bending direction, and W2 is the bending width of the flat portions 70a and 70b in the perpendicular direction. S3 is the cross-sectional area of the bent portion 70c, and S4 is the cross-sectional area of the flat portions 70a and 70b. The bending width W1 of the bent portion 70c is smaller than the bending width W2 of the flat portions 70a and 70b (W1<W2). As a result, the cross-sectional area S3 is smaller than the cross-sectional area S4 (S3<S4), and the elastic force of the inlet sheet metal 10 after welding can be reduced more than in a configuration in which the cross-sectional area is not reduced. In addition, the current I2 that does not contribute to welding flows during welding, but the resistance of the path increases as the cross-sectional area S3 of the bent portion 70c decreases, allowing the current I2 to be reduced.

As explained above, by reducing the bending width W1 of the bent portion 70c, the elastic force of the inlet metal plate 10 after welding can be reduced, and peeling of the welded portion can be prevented. In addition, the unnecessary current I2 that does not contribute to welding can be reduced, improving productivity.

In Example 4, we will explain a configuration in which the dissimilar metal bonding configurations of Examples 1 to 3 are applied to an earth terminal mounted on a power supply board used in an image forming apparatus, which is an example of an electronic device.

[Explanation of Laser Beam Printer]
FIG. 5 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 unit 1020, and a developing unit 1030. The photosensitive drum 1010 is an image carrier on which an electrostatic latent image is formed. The charging unit 1020 uniformly charges the photosensitive drum 1010. The developing unit 1030 develops the electrostatic latent image formed on the photosensitive drum 1010 with toner to form a toner image. The toner image formed on the photosensitive drum 1010 (on the image carrier) is transferred by a transfer unit 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 unit 1020, the developing unit 1030, and the transfer unit 1050 constitute an image forming unit. The printer 1000 also includes a power supply device 1080, which supplies power to the driving unit such as the motor and the control unit 5000. The printer 1000 includes a housing sheet metal 7, a housing sheet metal 6 fastened to the housing sheet metal 7 with a screw 8, and an inlet 5 held by the housing sheet metal 6 (see FIG. 1). AC power is supplied to the power supply device 1080 by fitting a power cord (not shown) to the inlet 5. The control unit 5000 includes a CPU (not shown) and controls the image forming operation by the image forming unit and the conveying operation of the sheet P. The housing sheet metal 6 corresponds to the sheets 30, 32, 34, and 36 in the first embodiment and the sheets 40, 42, 44, and 46 in the second embodiment. The image forming apparatus to which the welding method of the present invention can be applied is not limited to the configuration exemplified in FIG. 5.

[Internal Connection Configuration of Image Forming Apparatus]
6 is a diagram showing the configuration of the inlet 5, the power supply metal plate 53, the power supply board 50, and the ground terminal. The power supply metal plate 53 is a metal plate inside the printer 1000, and the power supply board 50 is a circuit board of the power supply device 1080. The power supply metal plate 53 has connection parts 52, 56, and 57. The power supply board 50 has board ground terminals 54 and 55.

The inlet terminal 1 of the inlet 5 is connected to the power supply board 50 by a cable 51a, and the inlet terminal 2 is connected to the power supply board 50 by a cable 51b. This allows power to be supplied from an AC power source (not shown) to the power supply board 50. The earth terminal 3 of the inlet 5 is connected to the power supply sheet metal 53 at a connection portion 52. The connection portion 52 is the portion where the first and second portions described in the previous embodiments are connected to the earth terminal 3 of the inlet 5. The board earth terminals 54 and 55 are terminals mounted on the power supply board 50, and are connected to the connection portions 56 and 57 of the power supply sheet metal 53, respectively. The power supply board 50 and the power supply sheet metal 53 are held by a frame mold (not shown).

[Application to connections 56 and 57]
7 is a diagram showing the details of the board earth terminal 55 and the connection part 57. The board earth terminal 55 is mounted on the component mounting surface of the power supply board 50, and is connected to the board pattern by soldering on the solder surface on the back side. The bent part 55a is a part formed by bending, and is bent in a direction approximately perpendicular to the surface of the power supply board 50, and has a shape extending to the outside of the power supply board 50. Here, one surface of the bent part 55a is surface 551a, and the other surface is surface 551b. The power supply sheet metal 53 has a first part 53a, a second part 53b, and a bent part 53e.

The first part 53a and the second part 53b of the power supply sheet metal 53 sandwich the bent part 55a of the board earth terminal 55. The first part 53a and the surface 551a of the bent part 55a are joined by welding, and the second part 53b and the surface 551b of the bent part 55a are joined by welding. The first part 53a and the second part 53b each have a protrusion (not shown) as described in Examples 1 and 2. The shape and configuration of the protrusion are the same as those described in Examples 1 and 2, and therefore a description thereof will be omitted. The board earth terminal 54 and the connection part 56 also have a similar configuration, and therefore a description thereof will be omitted.

By adopting the above-mentioned configuration, the protrusion of the present invention can also be applied to the board earth terminal of the power supply board used in the image forming device. The protrusion may also be provided on the board earth terminal. As described above, according to the third embodiment, it is possible to reduce welding defects and improve productivity.

3 Earth terminal 30, 32 Metal plate 30a, 32a First portion 30b, 32b Second portion 31a, 31b, 33a, 33b Projection portion

Claims (15)

a welding process in which, in a state in which a third member made of a third metal and held by a molding member is sandwiched between a first member made of a first metal and a second member made of a second metal, a first electrode is brought into contact with the first member, a second electrode is brought into contact with the second member, and a force is applied to each of the first electrode and the second electrode toward the third member to pass a current therethrough;
the first member has at least one first protrusion protruding toward the third member and in contact with the third member , and/or the second member has at least one second protrusion protruding toward the third member and in contact with the third member ;
a welding method characterized in that, in the welding process, the first member and the second member are separated from the mold member, the first member and a first surface of the third member are joined, and the second member and a second surface of the third member opposite to the first surface are joined. a welding process in which, in a state in which a third member made of a third metal and held by a molding member is sandwiched between a first member made of a first metal and a second member made of a second metal, a first electrode is brought into contact with the first member, a second electrode is brought into contact with the second member, and a force is applied to each of the first electrode and the second electrode toward the third member to pass a current therethrough;
the third member has at least one first protrusion on a first surface that protrudes toward the first member and contacts the first member , and/or the third member has at least one second protrusion on a second surface opposite to the first surface that protrudes toward the second member and contacts the second member ,
a welding method characterized in that, in the welding process, the first member and the second member are separated from the mold member, the first member and the first surface of the third member are joined, and the second member and the second surface of the third member are joined. The welding method according to claim 1 or 2, characterized in that the first protrusion and/or the second protrusion are point-shaped. A plurality of the first protrusions;
A plurality of the second protrusions;
Equipped with
The welding method according to claim 3 , wherein the number of the first projections is greater than the number of the second projections. the first protrusion is a protrusion that generates heat due to the Peltier effect in the welding process,
The welding method according to claim 4, wherein the second protrusion is a protrusion that absorbs heat due to the Peltier effect. The welding method according to claim 1 or 2, characterized in that the first protrusion and/or the second protrusion are linear. the first protrusion has a linear shape;
3. The welding method according to claim 1, wherein the second protrusion is point-shaped. the first protrusion is a protrusion that generates heat due to the Peltier effect in the welding process,
The welding method according to claim 7, wherein the second protrusion is a protrusion that absorbs heat due to the Peltier effect. the third member is a ground terminal of the inlet,
The welding method according to any one of claims 1 to 8, wherein the first member and the second member are metal plates that hold the inlet. the third member is a ground terminal mounted on a substrate,
9. The welding method according to claim 1, wherein the first member and the second member are metal plates included in an electronic device having the circuit board. the first metal and the second metal are iron;
11. The method according to claim 9 or 10, wherein the third metal is copper. 12. The welding method according to claim 1, wherein the first member and the second member are connected by a bent portion so that the first member and the second member are integrally formed. The welding method according to claim 12, wherein a cross-sectional area of the bent portion is smaller than a cross-sectional area of the flat portion of the first member and a cross-sectional area of the flat portion of the second member. The welding method according to claim 12 or 13, wherein a hole is formed in the bent portion. 15. The welding method according to claim 1, wherein the first member, the second member, and the third member are provided in an image forming device that forms an image on a recording material.

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