JP5136184B2 - Method for joining metal members - Google Patents

Description

  The present invention provides a first metal member having a main body portion having a predetermined thickness and a cylindrical portion protruding from the main body portion, and a second metal member having a fitting hole into which the cylindrical portion of the first metal member is inserted. Are connected to each other by resistance heat by energization.

  Conventionally, as shown in Patent Document 1 below, in a method of manufacturing a transmission gear in which a synchronization clutch gear is inserted into a transmission main gear and integrated by electron beam welding, Previously, a portion near the tooth portion of the clutch gear is joined to the main gear by electric resistance spot welding.

According to the method disclosed in Patent Document 1, since the portion near the tooth portion of the clutch gear is joined by electric resistance welding before performing electron beam welding, when performing electron beam welding thereafter. There are advantages such as preventing distortion and warping of the teeth of the clutch gear and ensuring sufficient dimensional accuracy after welding.
JP 2004-11816 A

  However, in the method of Patent Document 1 in which both electric resistance welding and electron beam welding are used, since it is necessary to perform welding in two steps, there is a problem that reduction in production efficiency is inevitable. Moreover, since two types of welding equipment for performing electric resistance welding and electron beam welding are required, there is also a problem that equipment costs increase.

  This invention is made | formed in view of the above situations, and provides the joining method of the metal member which can perform joining more efficiently, ensuring sufficient dimensional accuracy and joining strength. Objective.

  In order to solve the above problems, the present invention inserts a first metal member having a main body portion having a predetermined thickness and a cylindrical portion protruding from the main body portion in the thickness direction, and the cylindrical portion of the first metal member. A method of joining a second metal member having a fitting hole by resistance heat by energization, wherein the wall surface of the main body portion of the first metal member and the opposing surface of the second metal member facing this A step of providing a protrusion with a predetermined height on either one, the cylindrical portion of the first metal member is inserted into the fitting hole of the second metal member, and the peripheral surfaces of both are brought into contact with each other; The step of bringing the protruding portion into contact with the opposing surface of the mating side, and in this state, by energizing the first and second metal members while pressing in the approaching direction, the protruding portion and the opposing surface of the mating side While joining the contact portion, each of the cylindrical portion and the fitting hole It is characterized in that a step of joining the contact portions of the face with each other (Claim 1).

  According to the present invention, the cylindrical portion of the first metal member is inserted into the fitting hole of the second metal member so that the peripheral surfaces of both are brought into contact with each other, and one of the first and second metal members By energizing in a state where the protrusion provided on the other side is in contact with the opposing surface of the other party, the axial center of the two metal members is relatively easily aligned, while the opposing surface of the opposite side And both the cylindrical portion and the contact portion between the peripheral surfaces of the fitting hole can be joined at the same time. Therefore, the first and second metal members can be bonded with high strength through the two contact portions while sufficiently securing the dimensional accuracy (concentricity) after bonding, and once. There is an advantage that the working efficiency can be effectively improved by joining the two contact portions at the same time by energization.

  In the present invention, preferably, the first metal member and the second metal member are pressurized and energized using a pair of electrodes disposed opposite to each other with the two metal members interposed therebetween.

  If it does in this way, there exists an advantage that a metal member can be joined more efficiently, aiming at the simplification of an installation.

  The joining method of the present invention can be suitably applied when, for example, the first metal member is a gear for a transmission and the second metal member is a synchro cone (Claim 3).

  In this way, there is an advantage that gears and synchro cones that require relatively high dimensional accuracy and joint strength can be joined appropriately.

  Further, in this case, a ring-shaped receiving portion that is positioned radially outward from the protruding portion is formed on one of the gear and the synchro cone, and when the joining of the gear and the synchro cone is completed, the receiving portion is It is preferable to make it contact | abut to the wall surface of the said synchro cone.

  By doing so, there is an advantage that, when the joining is completed, the axial position of the synchrocone can be accurately positioned with respect to the gear, and the dimensional accuracy after joining can be improved more effectively.

  As described above, according to the method for joining metal members of the present invention, the metal members can be joined more efficiently while sufficiently ensuring dimensional accuracy and joining strength.

<Embodiment 1>
FIG. 1 is a view for explaining a method for joining metal members according to the first embodiment of the present invention, and is an exploded sectional view showing the shapes of a gear 1 and a synchro cone 2 as joining objects. In the example of FIG. 1, the gear 1 is a driven gear provided in a manual transmission for an automobile, and the synchro cone 2 is a component joined to the gear 1 as a component of a so-called synchromesh (synchronous meshing mechanism). It is. As the material of the gear 1 and the synchro cone 2, for example, carburized and quenched steel such as SCr steel is used.

  The gear 1 corresponds to an example of a first metal member of the present invention. The gear 1 is formed in a disc shape having a predetermined thickness and has a tooth portion G1 on the outer peripheral portion thereof. And a cylindrical cylindrical portion 4 protruding in the thickness direction along the axis X. The gear 1 is provided with an insertion hole 5 penetrating in the thickness direction over the main body portion 3 and the cylindrical portion 4, and a main shaft (not shown) slides into the insertion hole 5 when the transmission is assembled. It is inserted in a possible manner (or in a rollable manner via a bearing).

  On the other hand, the synchro cone 2 corresponds to an example of the second metal member of the present invention, and includes a main body portion 11 and a cone portion 12 protruding from the main body portion 11. Among these, the main body portion 11 has a fitting hole 10 having a predetermined radius at the center thereof and a tooth portion G2 at the outer peripheral portion. On the other hand, the cone portion 12 is made of a ring-shaped member having a hole 16 having a diameter larger than that of the fitting hole 10, and an outer peripheral surface thereof is formed in a tapered shape. During the synchronization operation of the transmission, the tapered outer peripheral surface of the cone portion 12 is brought into pressure contact with the inner peripheral surface of the synchro ring (not shown) to synchronize the rotational speed.

  The inner peripheral surface of the fitting hole 10 of the synchro cone 2 is formed in a stepped shape so that the inner diameter of the upper portion thereof is slightly smaller than other portions. Among these, the upper peripheral surface of the fitting hole 10 having a relatively small inner diameter is a small diameter portion 10a, and the inner diameter of the small diameter portion 10a is substantially the same value as the outer diameter of the cylindrical portion 4 of the gear 1. Yes. When the gear 1 and the synchro cone 2 are joined, the cylindrical portion 4 of the gear 1 is inserted into the fitting hole 10 so that the small-diameter portion 10a of the fitting hole 10 is the outer peripheral surface of the cylindrical portion 4. The contact portion is joined by the resistance heat of the current flowing in this state (details will be described later). In the above configuration, “the inner diameter of the small-diameter portion 10a and the outer diameter of the cylindrical portion 4 are substantially the same” means that a slight gap or tightening allowance that is about the processing tolerance may exist between the two. That means.

  As shown in FIGS. 1 and 6 and the like, a protrusion 15 having a predetermined height is provided on the facing surface 13 of the synchrocone 2 that faces the main body 3 of the gear 1 at the time of joining. The protrusion 15 is a ring-shaped protrusion whose diameter is larger than the inner diameter of the fitting hole 10 (the diameter is D in FIG. 1), and the fitting hole is centered on the axis Y of the synchrocone 2. 10 and concentric circles. The protrusion 15 can be formed at the same time as machining the facing surface 13 of the gear 1, for example.

  On the other hand, of the main body 3 of the gear 1, a pair of receiving portions 8 a having different diameters formed in a ring shape around the shaft center X of the gear 1 is formed on the opposing surface 6 that faces the synchrocone 2 at the time of joining. , 8b are projected. Of these, the diameter of the receiving portion 8a is larger than the diameter D of the protruding portion 15 of the synchrocone 2, and the diameter of the other receiving portion 8b is smaller than the diameter D of the protruding portion 15. ing. Further, as shown in FIG. 5 and the like, the protruding height of the receiving portions 8a and 8b is set to a value smaller than the protruding height of the protruding portion 15, and when the gear 1 and the synchro cone 2 are joined. When the projection 15 abuts against the opposing surface 6 on the other side (more specifically, the surface between the receiving portions 8a and 8b), the opposing surface 13 of the synchrocone 2 and the receiving portions 8a and 8b A predetermined gap is formed between them.

  Next, a procedure for joining the gear 1 and the synchro cone 2 configured as described above will be described with reference to FIGS. The bonding here is performed using a bonding apparatus including the upper electrode 21 and the lower electrode 22 shown in FIG. In the following description, the upper electrode 21 and the lower electrode 22 are disposed so as to face each other in the vertical direction and the gear 1 and the synchrocone 2 are sandwiched between them. It is of course possible to perform the joining in a state where the 22s are arranged opposite to each other in the horizontal direction.

  As shown in FIGS. 2 to 5, the lower electrode 22 surrounds a base portion 27, a protruding shaft portion 28 provided so as to protrude upward from the base portion 27, and an outer periphery of the protruding shaft portion 28. And a ring-shaped electrode portion 29 provided as described above. Such a lower electrode 22 has the protruding shaft portion 28 inserted into the insertion hole 5 of the gear 1 and a seating surface portion 7 formed of a lower peripheral portion of the insertion hole 5 at the time of joining work. It is used in a state where the upper end surface is abutted. The outer diameter of the protruding shaft portion 28 is made somewhat smaller than the inner diameter of the insertion hole 5 of the gear 1 so that the protruding shaft portion 28 is inserted into the insertion hole 5 relatively smoothly. Yes.

  On the other hand, the upper electrode 21 has a base portion 23 and an electrode portion 24 attached to the lower surface of the base portion 23, as shown in FIG. The electrode portion 24 is formed of a cylindrical body having a concave portion that opens downward, and the lower end surface of the electrode portion 24 is abutted against the seat surface portion 14 formed of the upper end of the cone portion 12 of the synchro cone 2 at the time of joining work. It has become.

  Further, an AC type or DC type power supply device 30 shown in FIGS. 4 and 5 is provided between the electrode portions 24 and 29 of the upper electrode 21 and the lower electrode 22, and this power supply device. A high voltage for bonding supplied from 30 is applied between the electrode portions 24 and 29. A predetermined current flows between the gear 1 and the synchro cone 2 when the high voltage is applied to the gear 1 and the synchro cone 2 with the electrode portions 24 and 29 being pressed. Both are joined by resistance heat caused by the energization.

  In order to join the gear 1 and the synchrocone 2 using the joining apparatus configured as described above, first, the gear 1 is set on the lower electrode 22 as shown in FIG. Specifically, by bringing the gear 1 close to the lower electrode 22 from above, the protruding shaft portion 28 of the lower electrode 22 is inserted into the insertion hole 5 of the gear 1 and the seat surface portion 7 of the gear 1 is moved. It is made to contact | abut to the upper end surface of the electrode part 25. FIG. Accordingly, the gear 1 is set in a state where the gear 1 is positioned in the radial direction and the axial direction (vertical direction) with respect to the lower electrode 22.

  Next, as shown in FIG. 3, the synchro cone 2 is made to approach the gear 1 set on the lower electrode 22 from above, so that the cylindrical portion 4 of the gear 1 is inserted into the fitting hole 10 of the synchro cone 2. Insert. However, as described above, since the inner diameter of the small diameter portion 10a in the fitting hole 10 is substantially the same as the outer diameter of the cylindrical portion 4, the cylindrical portion 4 is completely inserted into the fitting hole 10 at this time. The synchro cone 2 is temporarily fixed to the gear 1 during the insertion. That is, even if the cylindrical portion 4 is to be inserted into the fitting hole 10, when the upper end portion of the cylindrical portion 4 reaches the position of the small diameter portion 10 a of the fitting hole 10, the inner peripheral surface of the small diameter portion 10 a Since the outer peripheral surface of the cylindrical portion 4 comes into contact with each other, the synchro cone 2 is moved to an insertion completion position (that is, a position at which the opposite surfaces 13 and 6 of the synchro cone 2 and the gear 1 abut each other; see FIG. 4). Without moving, it is temporarily fixed in the middle and is held in the state of FIG. In this embodiment, as shown in FIG. 2, after setting the gear 1 to the lower electrode 22, the cylindrical portion of the gear 1 is partially inserted into the fitting hole 10 of the synchro cone 2 as shown in FIG. Although the synchro cone 2 is temporarily fixed by being inserted, it is naturally possible to set the gear 1 on the lower electrode 22 after performing the temporary lock of the synchro cone 2 in advance.

  Next, the upper electrode 21 (see FIG. 4) is approached from above with respect to the synchro cone 2 temporarily fixed to the gear 1 as described above, and the lower end surface of the electrode portion 24 is brought to the seat surface portion 14 of the synchro cone 2. In this state, a downward pressing force F1 (for example, 1 ton) is applied to the upper electrode 21 in this state, so that the insertion completion position shown in FIG. The synchro cone 2 is pushed into a position where the projection 15 abuts against the facing surface 6 of the gear 1.

  Finally, as shown in FIG. 5, the pressure applied to the upper electrode 21 is increased to a pressure F2 (for example, 8 ton) larger than the pressure F1 at the time of FIG. 4, and the power supply is performed. By operating the device 30 and applying a high voltage for bonding between the upper electrode 21 and the lower electrode 22, while pressing the gear 1 and the synchrocone 2 in the approaching direction with a relatively large force, A large current A (for example, about 320 kA) is instantaneously passed between them, and the gear 1 and the synchro cone 2 are joined by resistance heat at this time.

  Specifically, the current A flowing between the gear 1 and the synchrocone 2 is the contact portions S1 and S2 shown in FIG. 6, that is, the contact portion S1 between the projecting portion 15 and the opposing surface 6 on the other side, and the cylinder. It flows through the contact portion S2 between the peripheral surfaces of the portion 4 and the fitting hole 10, respectively. Then, the metal at the contact portions S1 and S2 is softened or melted by the resistance heat at this time, and the contact portions S1 and S2 are integrated as a result of the energization being stopped and the metal at the portions being hardened again. The gear 1 and the synchro cone 2 are joined. In the above configuration, “the metal is softened or melted” means that the metal of the contact portions S1 and S2 may be completely melted by resistance heat by energization or may be softened at a lower temperature. That is good. That is, in the form of joining in the present invention, the metal of the contact portions S1 and S2 is re-solidified by raising the temperature to the melting point or higher, and softened at a temperature lower than the melting point to cause plastic flow, Both are included in the case of joining in a state.

  FIG. 7 is a view showing a state where the joining of the gear 1 and the synchro cone 2 is completed. As shown in this figure, when the joining is completed, the projection 15 of the synchrocone 2 is crushed, and the opposing surface 13 of the synchrocone 2 contacts the receiving portions 8a and 8b provided on the opposing surface 6 of the gear 1. It will be in contact. That is, as the protrusion 15 is softened or melted by resistance heat due to energization, a pressure F2 (FIG. 5) is applied to the synchrocone 2 downward from the upper electrode 21, whereby the protrusion 15 As a result, the entire synchro cone 2 is displaced downward, and the opposing surface 13 of the synchro cone 2 comes into contact with the receiving portions 8a and 8b of the gear 1. Thereby, the axial position of the synchrocone 2 is positioned with respect to the gear 1, and the periphery of the contact portion S1 between the projection 15 and the facing surface 6 is sealed from the outside by the receiving portions 8a and 8b.

  As described above, there is a slight gap or tightening allowance between the cylindrical portion 4 of the gear 1 and the small-diameter portion 10a of the synchrocone 2 at the time before energization is performed. In such a situation, when a predetermined current flows between the gear 1 and the synchro cone 2 in such a situation, there is a clearance as well as a clearance between them. However, it is considered that the joining of the cylindrical portion 4 and the small diameter portion 10a (joining of the contact portion S2) is performed without any problem. That is, even if there is a slight gap as described above between the cylindrical portion 4 and the small diameter portion 10a, it is considered that a part of the peripheral surface of both is always in contact when viewed locally. From that point, resistance heat is generated by energization, and the area of the contact portion is increased with the subsequent softening or melting of the metal, so that the cylindrical portion 4 and the small-diameter portion 10a are finally substantially completely formed. Joined over the circumference.

  As described above, the metal member joining method according to the first embodiment includes the gear 1 having the main body 3 having a predetermined thickness and the cylindrical portion 4 protruding from the main body 3 in the thickness direction, and the cylindrical portion 4 of the gear 1. The synchro cone 2 having the fitting hole 10 into which is inserted is joined by resistance heat by energization. In this joining method, a step of providing a protrusion 15 having a predetermined height on the facing surface 13 of the synchrocone 2 facing the main body 3 of the gear 1 and the cylindrical part 4 of the gear 1 are connected to the synchrocone. 2 is inserted into the two fitting holes 10 and the peripheral surfaces of the two are brought into contact with each other, and the projecting portion 15 is brought into contact with the opposing surface 6 of the other side (gear 1). By energizing the synchrocone 2 while pressing it in the approaching direction, the contact portion S1 between the protruding portion 15 and the opposing surface 6 is joined, and the peripheral surfaces of the cylindrical portion 4 and the fitting hole 10 are connected to each other. And joining the contact portion S2. According to this method, there is an advantage that the metal members can be joined more efficiently while sufficiently securing the dimensional accuracy and the joining strength.

  That is, in the first embodiment, the cylindrical portion 4 of the gear 1 is inserted into the fitting hole 10 of the synchrocone 2 so that the peripheral surfaces of both are brought into contact with each other (that is, the outer peripheral surface of the cylindrical portion 4 and the fitting hole 10). The small diameter portion 10a is in contact with the inner peripheral surface of the small cone portion 10a) and the projection 15 provided on the synchrocone 2 is in contact with the opposing surface 6 of the gear 1 to conduct current. While the axes (X, Y in FIG. 1) of the synchrocone 2 are relatively easily aligned, the contact portion S1 between the projection 15 and the opposing surface 6 on the other side, the cylindrical portion 4 and the fitting hole 10 Both the contact portions S2 of the peripheral surfaces can be joined at the same time. For this reason, the gear 1 and the synchro cone 2 can be joined with high strength through the two contact portions S1 and S2 while ensuring sufficient dimensional accuracy (concentricity) after joining, and once. There is an advantage that the working efficiency can be effectively improved by joining the contact portions S1 and S2 at the same time by energization.

  Moreover, in the said 1st Embodiment, the opposing surface 6 of the gear 1 is a ring shape larger or smaller than the diameter D of the projection 15 (that is, located radially outside or inside the projection 15). Since the receiving portions 8a and 8b are formed and the receiving portions 8a and 8b are brought into contact with the wall surface (opposing surface 13) of the synchrocone 2 when the joining of the gear 1 and the synchrocone 2 is completed, the synchro There is an advantage that the axial position of the cone 2 can be accurately positioned with respect to the gear 1 and the dimensional accuracy after joining can be improved more effectively. In addition, as described above, the receiving portions 8a and 8b are brought into contact with the opposing surface 13 of the synchrocone 2 to eliminate the gap between them, for example, shot peening for the gear 1 and the synchrocone 2 as post-processing after joining. There is also an advantage that it is possible to effectively prevent the shot powder from being clogged in a slight gap around the contact portion S1.

  In the first embodiment, the two receiving portions 8a and 8b positioned on the radially outer side and the inner side of the protrusion 15 are provided on the facing surface 6 of the gear 1. However, the synchro cone is prevented from being clogged with shot powder. In order to position 2, it suffices that at least the radially outer receiving portion 8 a exists, and therefore the radially inner receiving portion 8 b may be omitted.

  In the first embodiment, pressurization and energization are performed using a pair of electrodes 21 and 22 arranged opposite to each other with the gear 1 and the synchrocone 2 interposed therebetween. It is of course possible to energize using a separate electrode while applying pressure with a dedicated press. However, in this case, both the equipment for the press machine and the equipment for the electrode are necessary, so that the entire equipment becomes complicated. On the other hand, when both the pressurization and energization of the gear 1 and the synchrocone 2 are performed using the pair of electrodes 21 and 22 as in the first embodiment, the gear 1 and the synchrocone are provided. There exists an advantage that joining of 2 can be performed efficiently using simpler equipment.

  Moreover, in the said 1st Embodiment, while providing the projection part 15 in the opposing surface 13 of the synchrocone 2 and providing the receiving parts 8a and 8b in the opposing surface 6 of the gear 1, conversely to this, the gear 1 side Protruding part 15 may be provided on the side and receiving parts 8a and 8b may be provided on the synchro cone 2 side. Further, the protruding portion 15 and the receiving portions 8a and 8b may be provided together on either the gear 1 or the synchro cone 2.

  In the first embodiment, the case where the joining method of the present invention is applied to the joining of the gear 1 for the manual transmission (MT) and the synchro cone 2 has been described as an example. It can be widely applied to the joining of metal members that require a high degree of dimensional accuracy and joining strength. Next, an example in which the joining method of the present invention is applied to a metal member different from the first embodiment will be described as a second embodiment.

<Embodiment 2>
FIG. 8 is a view for explaining a method for joining metal members according to the second embodiment of the present invention. Here, unlike the first embodiment, the joining method of the present invention is applied to a one-way clutch outer race 51 and a clutch drum 52 which are parts for an automatic transmission (AT).

  The one-way clutch outer race 51 (hereinafter simply referred to as the outer race 51) has a main body portion 53 having spline teeth G3 formed on the outer periphery and a multi-stage cylindrical portion 54 protruding from the main body portion 53 in the thickness direction. doing. On the other hand, the clutch drum 52 is formed with a fitting hole 60 having an inner diameter substantially the same as the outer diameter of the base end portion of the cylindrical portion 54, and the cylindrical portion 54 is inserted into the fitting hole 60. In this state, the outer race 51 and the clutch drum 52 are joined. That is, in this embodiment, the outer race 51 corresponds to the first metal member according to the present invention, and the clutch drum 52 corresponds to the second metal member according to the present invention.

  Of the main body 53 of the outer race 51, a projecting portion 65 having a predetermined height is provided on the facing surface 56 facing the clutch drum 52, and this projecting portion 65 faces the facing surface of the clutch drum 52 during joining. 63 comes into contact. Further, a receiving portion 58 having a protruding height lower than that of the protruding portion 65 is provided in a portion of the facing surface 56 of the outer race 51 that is located on the radially outer side of the protruding portion 65. The facing surface 63 of the clutch drum 52 comes into contact with the receiving portion 58 in a state where the protruding portion 65 is crushed. That is, in the present embodiment, unlike the first embodiment, the outer race 51 corresponding to the first metal member is provided with both the protruding portion 65 and the receiving portion 58.

  The outer race 51 and the clutch drum 52 configured as described above are joined using a pair of electrodes 71 and 72 shown in FIG. Since the joining procedure is the same as in the first embodiment, a detailed description thereof is omitted.

  When the joining as described above is completed, the contact portions S3 and S4 shown in FIG. 10, that is, the contact portion S3 between the protrusion 65 and the facing surface 63, the cylindrical portion 54, and the fitting hole 60 are obtained. Both the contact portions S4 of the peripheral surfaces are joined at the same time.

  According to the second embodiment of the present invention as described above, the outer race 51 and the clutch drum 52 are joined at the time of joining in the first embodiment (that is, when the gear 1 and the synchro cone 2 are joined). Similarly, there is an advantage that it can be performed more efficiently while sufficiently securing dimensional accuracy and bonding strength.

It is a figure for demonstrating the joining method of the metal member concerning 1st Embodiment of this invention, and is an exploded sectional view which shows the shape of the gear and synchro cone as a joining object. It is a figure which shows the state which set the said gear to the lower electrode. It is a figure which shows the state which temporarily fixed the synchro cone to the gear set to the said lower electrode. It is a figure which shows the state which pressurized the said synchro cone from the top with the upper electrode, and was pushed in to the insertion completion position. It is a figure which shows the condition when the electric current for joining is sent between the said upper electrode and a lower electrode. FIG. 6 is a partially enlarged view of FIGS. 4 and 5. FIG. 7 is a view corresponding to FIG. 6 illustrating a situation when the joining is completed. It is a figure for demonstrating 2nd Embodiment of the joining method of the metal member concerning this invention, and is an exploded sectional view which shows the shape of the outer race and clutch drum as joining object. It is a figure which shows the condition when joining the said outer race and a clutch drum. It is an enlarged step view which shows the condition at the time of joining completion.

Explanation of symbols

1 Gear (first metal member)
2 Synchrocone (second metal member)
DESCRIPTION OF SYMBOLS 3 Main-body part 4 Cylindrical part 6 Opposite surface 8a, 8b Receiving part 10 Fitting hole 13 Opposed surface 15 Protrusion part 21 Upper electrode (electrode)
22 Lower electrode (electrode)
S1, S2 contact part 51 outer race (first metal member)
52 Clutch drum (second metal member)
54 Cylindrical part 56 Opposing surface 58 Receiving part 60 Fitting hole 63 Opposing surface 65 Protruding part 71, 72 Electrode S3, S4 Contact part

Claims (4)

A first metal member having a main body portion having a predetermined thickness and a cylindrical portion protruding from the main body portion and a second metal member having a fitting hole into which the cylindrical portion of the first metal member is inserted are energized. It is a method of joining with resistance heat by,
Providing a protrusion having a predetermined height on either the wall surface of the main body of the first metal member or the opposing surface of the second metal member facing the main body;
Inserting the cylindrical portion of the first metal member into the fitting hole of the second metal member to bring each peripheral surface into contact with each other, and bringing the protruding portion into contact with the opposing surface;
In this state, the first and second metal members are energized while being pressed in the approaching direction, thereby joining the contact portion between the protruding portion and the opposing surface on the other side, and the cylindrical portion and the fitting hole. And a step of joining the contact portions of the peripheral surfaces to each other. In the joining method of the metal member of Claim 1,
A method for joining metal members, wherein the pressurization and energization of the first and second metal members are performed using a pair of electrodes arranged opposite to each other with both metal members interposed therebetween. In the joining method of the metal member of Claim 1 or 2,
The metal member joining method, wherein the first metal member is a gear for a transmission, and the second metal member is a synchro cone. In the joining method of the metal member of Claim 3,
Either one of the gear and the synchro cone is formed with a ring-shaped receiving portion positioned radially outward from the protruding portion, and when the joining of the gear and the synchro cone is completed, the receiving portion is attached to the synchro cone. A method for joining metal members, wherein the metal members are brought into contact with a wall surface.

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