JP2013034998A - Method for manufacturing power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a power transmission device in which a gear wheel and a power transmission member are joined with high strength in a simple process.SOLUTION: The method for manufacturing the power transmission device 1 with a ring gear 10 and a hub member 20 integrally formed with the same rotation axis O1 as the center includes a mating surface forming process for forming a first mating surface 12 of conical shape at the ring gear 10, forming a second mating surface 24 of conical shape mating with the first mating surface 12, at the hub member 20, forming a protrusion 14 at the ring gear 10, and forming a ring groove 26 in the hub member 20; a joining process for energizing the ring gear 10 and the hub member 20 in the abutting state of the protrusion 14 and the bottom face 26a of the ring groove 26 while placing the first mating surface 12 and the second mating surface 24 to face each other, and joining the protrusion 14 to the bottom face 26a of the ring groove 26 by electric resistance welding; and a pressing process for pressing the ring gear 10 and the hub member 20 in a relatively approaching direction to bring the first mating surface 12 and the second mating surface 24 into close contact.

Description

  The present invention relates to a method for manufacturing a power transmission device including a large gear (ring gear, etc.) and a power transmission member (hub member, differential case, etc.).

For example, in a two-wheeled vehicle, power generated by an internal combustion engine is transmitted to rear wheels (drive wheels) via a chain and a propulsion shaft. When transmitting through the propulsion shaft, a final reduction gear is provided coaxially with the rear wheel, and the power of the propulsion shaft is deflected by approximately 90 ° within the final reduction gear.
Such a final reduction gear is configured to include a drive pinion to which the power of the propulsion shaft is input and a power transmission device, and the power transmission device is integral with the ring gear and the ring gear with which the drive pinion meshes. And a hub member (power transmission member) that rotates around the same rotation axis as the rear wheel. In general, a tooth surface of a bevel gear (bevel gear) is formed at a meshing portion between the drive pinion and the ring gear.

  Here, the ring gear and the hub member prevent relative rotation in the circumferential direction by press-fitting a part of the hub member into the ring gear and then performing spline fitting (coupling). Further, as a retaining in the axial direction, the spline shaft after press-fitting (a part of the hub member inserted into the ring gear) is caulked. Thus, since it crimped after press-fit, man-hours are required for fixation with a ring gear and a hub member.

  On the other hand, in a four-wheeled vehicle, the power generated by the internal combustion engine is input to a final reduction device provided at the center of the left and right rear wheels (drive wheels) via, for example, a transmission and a propeller shaft. The The final reduction gear is composed of a drive pinion to which the power of the propulsion shaft is input and a drive pinion that meshes with the drive pinion and deflects the power by 90 ° and is fixed to a differential case to be described later. Moving device). The differential device is a device for differentially rotating the left and right rear wheels when traveling on a curve, a cast or forged differential case (power transmission member), and a differential gear (pinion gear, side gear) accommodated therein , And is configured.

  Here, the ring gear and the differential case are integrated by, for example, forming a flange on the outer peripheral surface of the differential case, fitting the ring gear to the differential case, and then fastening the ring gear and the flange with a bolt. Therefore, since the bolt is responsible for a part of power transmission, it is necessary to be formed of a high-strength material, and the bolt needs to be fastened with high tightening. The assembly work is complicated.

  Therefore, in order to solve such a problem, a technique has been proposed in which the ring gear and the power transmission member (hub member, differential case) are integrated by laser beam welding or electron beam welding (see Patent Documents 1 to 3). . Further, in order to increase the productivity of the power transmission device over laser beam welding and electron beam welding, a technique of integrating by electric resistance welding has been proposed (see Patent Document 4).

JP 2010-180976 A JP 2010-242930 A JP 2011-47420 A JP 2011-98358 A

Incidentally, in Patent Document 4, the fitting length between the ring gear and the differential case is determined in consideration of the meshing reaction force of the ring gear that is a spur gear.
Here, when the ring gear is changed to a bevel gear (bevel gear), the reaction force acting in the axial direction (in the direction of the rotation axis of the ring gear and the differential case) increases, so the fitting length between the ring gear and the differential case is increased. However, when the fitting length is increased in this way, energy (joining energy) for joining the ring gear and the differential case increases, and productivity may be lowered.

  Further, in this configuration, as the differential case is press-fitted into the hollow portion of the ring gear, the contact area between the ring gear and the differential case increases, and the joining energy may increase accordingly.

  Further, in this configuration, after the ring gear and the differential case are attached to the electric resistance welder, when the ring gear and the differential case are brought into contact with each other, the center of the ring gear and the differential case with respect to the electric resistance welder is displaced, the ring gear In addition, the contact range of both members may not be uniform in the circumferential direction due to processing errors on the contact surface of the differential case. If the contact range is not uniform in the circumferential direction in this way, there will be variations in the amount of electricity and heat generated in the circumferential direction, resulting in a non-uniform melt amount (penetration amount) and the center of the ring gear and the differential case. There is a risk that the center will be shifted.

  Furthermore, if the burrs generated in the electric resistance welding remain after the manufacture, and the burrs fall off during use of the power transmission device and the gears are engaged, the strength of the gears may be reduced.

  Then, this invention makes it a subject to provide the manufacturing method of the power transmission device which joins a large gear and a power transmission member with high intensity | strength by a simple process.

  As means for solving the above-mentioned problems, the present invention provides a power transmission device comprising a large gear and a power transmission member, wherein the large gear and the power transmission member are configured integrally and centered on the same rotating shaft. In the manufacturing method, a conical first mating surface centered on the rotation shaft is formed on the large gear, and a conical first mating surface is formed on the power transmission member about the rotation shaft. Forming two mating surfaces, forming a protruding portion protruding toward the other on one of the large gear and the power transmission member, and forming a recess facing the protruding portion on the other of the large gear and the power transmission member The large gear and the power transmission member are energized in a state where the projecting portion and the bottom surface of the recess are abutted with each other while the mating surface forming step is opposed to the first mating surface and the second mating surface. The protrusion and the recess A joining step for joining the bottom surface by electric resistance welding, and pressing the large gear and the power transmission member in a relatively close direction in the axial direction to bring the first mating surface and the second mating surface into close contact with each other. And a pressing step. A method of manufacturing a power transmission device, comprising:

Here, “conical shape” includes “conical shape”.
In addition, “adhering the first mating surface and the second mating surface” means not only that the first mating surface and the second mating surface are in close contact with each other, but also a linear shape as described later. And the like, which are partially adhered to each other.

  According to such a configuration, in the mating surface forming step, the conical first mating surface is formed on the large gear, the conical second mating surface is formed on the power transmission member, and the large gear and the power transmission member. A protrusion is formed on one of the two and a recess is formed on the other.

  And in a joining process, it supplies with electricity to a large gearwheel and a power transmission member in the state which faced the 1st mating surface and the 2nd mating surface, and the projection part and the bottom face of the crevice. Then, between the large gear and the power transmission member, only the abutting portion between the protruding portion and the bottom surface of the concave portion is energized, and the abutting portion generates heat based on the resistance. To do. Thereby, the protrusion part which comprises a butt | matching part, and the bottom face of a recessed part soften and plastically flow, and an electrical resistance welding is carried out to a protrusion part and the bottom face of a recessed part.

Then, before energization is stopped and the abutting portion is completely solidified, in the pressing step, the large gear and the power transmission member are pressed in a relatively approaching direction in the axial direction, and the first mating surface and the second mating surface are pressed. By bringing the mating surfaces into close contact with each other, the large gear and the power transmission member can be joined while matching the centers thereof.
The abutting portion (joining portion) is then naturally cooled to room temperature, for example, and the metal forming the projecting portion is solidified to form a joining surface.

  Here, since the first mating surface and the second mating surface are conical surfaces centering on the rotation axis after manufacture, in the pressing step, the first mating surface and the second mating surface are brought into close contact with each other, By eliminating the gap between them, the central axis of the large gear coincides with the central axis of the power transmission member. Therefore, there is no deviation in meshing between the large gear and its counterpart gear (such as the gear portion of the drive pinion).

  In addition, the protrusion softens and burr is generated by resistance heat, but this burr is generated in the recess on the other side (the other side) of the protrusion, and does not appear on the outer surface of the power transmission device after manufacturing. There is no risk of falling off during use of the device.

  As means for solving the above-mentioned problems, the present invention provides a power transmission device comprising a large gear and a power transmission member, wherein the large gear and the power transmission member are configured integrally and centered on the same rotating shaft. In the manufacturing method, a conical first mating surface centered on the rotation shaft is formed on the large gear, and a conical first mating surface is formed on the power transmission member about the rotation shaft. A mating surface forming step of forming two mating surfaces, forming a first recess in the large gear, and forming a second recess facing the first recess in the power transmission member; and the first mating surface and the first A state in which the joining assisting member is sandwiched between the first recess and the second recess while the two mating surfaces are opposed to each other, the first bottom surface of the first recess and the joining assisting member are abutted, and the second recess The second bottom surface of the steel and the joining auxiliary member In this state, the large gear and the power transmission member are energized, and the first bottom surface of the first recess and the joining auxiliary member are joined to the second bottom surface of the second recess and the joining auxiliary member by electric resistance welding, respectively. And a pressing step of pressing the large gear and the power transmission member in a relatively approaching direction in the axial direction so that the first mating surface and the second mating surface are brought into close contact with each other. It is the manufacturing method of the power transmission device characterized.

  According to such a configuration, in the mating surface forming step, the conical first mating surface is formed on the large gear, the conical second mating surface is formed on the power transmission member, and the first recess is formed on the large gear. And forming a second recess in the power transmission member.

  In the joining step, the first auxiliary surface and the second auxiliary surface are made to face each other, the auxiliary bonding member is sandwiched between the first concave portion and the second concave portion, and the first bottom surface of the first concave portion and the auxiliary auxiliary member are butted together. The large gear and the power transmission member are energized in a state where the second bottom surface of the second recess and the joining auxiliary member are abutted with each other. Then, between the large gear and the power transmission member, only through the joining auxiliary member, that is, the first bottom surface of the first recess and the first butting portion of the joining auxiliary member, the second bottom surface of the second recess, and Energization is performed so as to pass through the second butting portion of the joining auxiliary member, and the first butting portion and the second butting portion generate heat based on the resistance. Resistance heat is generated. As a result, the joining auxiliary member constituting the first abutting portion and the first bottom surface of the first recess, and the joining assisting member constituting the second abutting portion and the second bottom surface of the second recess soften and plastically flow, respectively. The first auxiliary bottom surface of the joining auxiliary member and the first concave portion and the second bottom surface of the auxiliary joining member and the second concave portion are electrically resistance welded, respectively.

Then, before energization is stopped and the abutting portion is completely solidified, in the pressing step, the large gear and the power transmission member are pressed in a relatively approaching direction in the axial direction, and the first mating surface and the second mating surface are pressed. By bringing the mating surfaces into close contact with each other, the large gear and the power transmission member can be joined while matching the centers thereof.
Here, since the first mating surface and the second mating surface are conical surfaces centering on the rotation axis after manufacture, in the pressing step, the first mating surface and the second mating surface are brought into close contact with each other, By eliminating the gap between them, the central axis of the large gear coincides with the central axis of the power transmission member. Therefore, there is no deviation in meshing between the large gear and its counterpart gear (such as the gear portion of the drive pinion).

  In addition, the joining auxiliary member softens due to resistance heat, and burrs are generated. These burrs are generated in the first concave portion or the second concave portion on the mating side and do not appear on the outer surface of the power transmission device after manufacture, and power transmission There is no risk of falling off during use of the device.

  Further, in the method for manufacturing the power transmission device, the first inclination angle of the first mating surface with respect to the rotating shaft and the second inclination angle of the second mating surface with respect to the rotating shaft may be different from each other. is there.

According to such a configuration, since the first inclination angle of the first mating surface and the second inclination angle of the second mating surface are different, the contact portion (matching portion) between the first mating surface and the second mating surface. Is linear, that is, circumferential around the rotation axis.
Thus, in the pressing step, when the large gear and the power transmission member are pressed in a direction relatively approaching in the axial direction, the pressing force is concentrated on the linear contact portion, and the large gear and / or the power transmission member is The contact portion is easily elastically deformed or plastically deformed. Therefore, in the axial direction, the large gear and the power transmission member are relatively easily approached.

  Therefore, the first facing surface (the back surface 13 in the embodiment described later) that faces the power transmission member other than the first mating surface, which is the surface of the large gear, comes into contact (contact) with the power transmission member and is easily adhered. . Similarly, a second opposing surface (a flange surface 25a in the embodiment described later) that is the surface of the power transmission member and faces the large gear other than the second mating surface abuts (contacts) the large gear and is in close contact therewith. It becomes easy to do.

Thus, in the power transmission device after manufacture, the first opposing surface of the large gear is in close contact with the power transmission member, and the second opposing surface of the power transmission member is in close contact with the large gear. Even if the gear receives a meshing reaction force in a direction in which the rotation shaft of the large gear falls from the rotation shaft of the power transmission member (a direction in which the rotation shaft of the large gear and the rotation shaft of the power transmission member are separated) Is less likely to fall with respect to the power transmission member, and the rotation shaft of the large gear and the rotation shaft of the power transmission member are difficult to shift.
In addition, it is preferable that a 1st opposing surface and a 2nd opposing surface are surfaces orthogonal to a press direction (rotation axis) like embodiment mentioned later, and, in an axial direction, it is the 1st opposing surface and It is preferable that the second facing surface is disposed so as to face the first facing surface and the second facing surface is in close contact with each other.

  In the method of manufacturing the power transmission device, it is preferable that one of the first mating surface and the second mating surface protrudes in an arc shape toward the other in a longitudinal sectional view.

According to such a configuration, since one of the first mating surface and the second mating surface protrudes in an arc shape toward the other, a contact portion (matching portion) between the first mating surface and the second mating surface. Is linear, that is, circumferential around the rotation axis.
Thus, in the pressing step, when the large gear and the power transmission member are pressed in a direction relatively approaching in the axial direction, the pressing force is concentrated on the linear contact portion, and the large gear and / or the power transmission member is The contact portion is easily elastically deformed or plastically deformed. Therefore, in the axial direction, the large gear and the power transmission member are relatively easily approached.

  Therefore, the first facing surface (the back surface 13 in the embodiment described later) that faces the power transmission member other than the first mating surface, which is the surface of the large gear, comes into contact (contact) with the power transmission member and is easily adhered. . Similarly, a second opposing surface (a flange surface 25a in the embodiment described later) that is the surface of the power transmission member and faces the large gear other than the second mating surface abuts (contacts) the large gear and is in close contact therewith. It becomes easy to do.

Thus, in the power transmission device after manufacture, the first opposing surface of the large gear is in close contact with the power transmission member, and the second opposing surface of the power transmission member is in close contact with the large gear. Even if the gear receives a meshing reaction force in a direction in which the rotation shaft of the large gear falls from the rotation shaft of the power transmission member (a direction in which the rotation shaft of the large gear and the rotation shaft of the power transmission member are separated) Is less likely to fall with respect to the power transmission member, and the rotation shaft of the large gear and the rotation shaft of the power transmission member are difficult to shift.
In addition, it is preferable that a 1st opposing surface and a 2nd opposing surface are surfaces orthogonal to a press direction (rotation axis) like embodiment mentioned later, and, in an axial direction, it is the 1st opposing surface and It is preferable that the second facing surface is disposed so as to face the first facing surface and the second facing surface is in close contact with each other.

  In the method for manufacturing a power transmission device, the power transmission member is preferably a hub member to which drive wheels are attached.

  According to such a configuration, it is possible to satisfactorily join the large gear and the hub member disposed on the coaxial line with the drive wheel.

  In the method for manufacturing the power transmission device, the power transmission member is preferably a differential case.

  According to such a configuration, the large gear and the differential case can be satisfactorily joined.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the power transmission device which joins a large gear and a power transmission member with high intensity | strength by a simple process can be provided.

It is sectional drawing of the final reduction gear provided with the power transmission device for two-wheeled vehicles which concerns on 1st Embodiment, and is a longitudinal cross-sectional view which passes along rotating shaft O1. (A) is a longitudinal cross-sectional view of the power transmission device according to the first embodiment, and (b) is an enlarged view of (a). (A) is the longitudinal cross-sectional view explaining the manufacturing method of the power transmission device which concerns on 1st Embodiment, Comprising: Before joining (before electric resistance welding), (b) is an enlarged view of (a). It is. (A) is the longitudinal cross-sectional view explaining the manufacturing method of the power transmission device which concerns on 1st Embodiment, Comprising: After joining (after electrical resistance welding), it has shown before pressing, (b) is (a). FIG. (A) is a longitudinal cross-sectional view of the power transmission device according to the second embodiment, and (b) is an enlarged view of (a). (A) is a longitudinal cross-sectional view of the power transmission device which concerns on 3rd Embodiment, (b) is an enlarged view of (a). (A) is a longitudinal cross-sectional view of the power transmission device which concerns on 4th Embodiment, (b) is an enlarged view of (a). It is a longitudinal cross-sectional view of the final reduction gear provided with the power transmission device for four-wheeled vehicles which concerns on 5th Embodiment.

<< First Embodiment >>
A first embodiment will be described with reference to FIGS.
Here, a configuration in which the power transmission device is applied to a rear wheel portion of a two-wheeled vehicle (vehicle) is illustrated. And in order to demonstrate clearly, "front and rear, right and left" are attached | subjected to FIGS. Note that “front / rear / left / right” corresponds to “front / rear / left / right” of a motorcycle. Moreover, in FIGS. 1-4, the clearance gap between the ring gear 10 and the hub member 20 is described rather large.

≪Configuration of final reduction gear≫
The final reduction gear 100 includes a drive pinion 110 that is connected to a propulsion shaft (not shown) and extends in the front-rear direction, and the power transmission device 1. 1 is a device for transmitting to the hub member 20 constituting the member 1.

  The drive pinion 110 is rotatably supported by a case 115 fixed to the vehicle body via a bearing 116. The front end of the drive pinion 110 is connected to the rear end of a propulsion shaft (not shown) via an appropriate connection mechanism, and the power of the propulsion shaft is input to the drive pinion 110.

  The gear part 111 of the drive pinion 110 meshes with a gear part 11 of the ring gear 10 described later.

≪Power transmission device configuration≫
The configuration of the power transmission device 1 will be described.
The power transmission device 1 includes a ring gear 10 (large gear) and a hub member 20 (power transmission member). The ring gear 10 and the hub member 20 are such that a protrusion 14 (protrusion), which will be described later, and a bottom surface 26a of the annular groove 26 are electrically resistance-welded and the first mating surface 12 and the second mating surface 24 are in close contact with each other. It is integrated with. The ring gear 10 and the hub member 20 are centered on the same rotation axis O1, and this rotation axis O1 is also the rotation center of the rear wheel. Moreover, the parts which comprise the power transmission device 1, such as the ring gear 10 and the hub member 20, are made of steel, for example. However, the material is not limited to steel, and any material that can be energized may be used, and a different material, for example, an aluminum alloy may be used to reduce weight.

<Ring gear>
The ring gear 10 is a ring-shaped component, and a hub member 20 is inserted into a hollow portion thereof and fixed to the hub member 20. The gear portion 11 of the ring gear 10 meshes with the gear portion 111 of the drive pinion 110.

  The inner peripheral surface of the ring gear 10 constitutes a first mating surface 12. The first mating surface 12 is a frustoconical (conical) surface with the rotation axis O1 as the center, that is, a tapered surface whose right end is reduced in diameter. That is, the inner diameter of the first mating surface 12 is gradually reduced from the left side to the right side.

  The hub member 20 side of the ring gear 10 spreads in a direction orthogonal to the rotation axis O1 and has a ring shape to form a flat back surface 13 (first facing surface). The back surface 13 faces a flange surface 25a described later. Yes. A rear surface 13 is formed with a ring-shaped (annular) protrusion 14 centering on the rotation axis O1 and protruding toward the hub member 20, and the protrusion 14 is accommodated in an annular groove 26 described later. In the annular groove 26, the bottom surface 26 a is welded (joined) and joined to the hub member 20.

<Hub member>
The hub member 20 is a component to which a rear wheel (not shown) as a driving wheel is attached. The hub member 20 includes a large diameter portion 21, a reduced diameter portion 22, and a small diameter portion 23 from the left side (one end side) toward the right side (the other end side). The large diameter portion 21 is rotatably supported by the case 32 via the bearings 31, 31, and the small diameter portion 23 is rotatably supported by the case 32 via the bearing 33. The wheel is attached to the left end surface of the large diameter portion 21.

  The reduced diameter portion 22 has a truncated cone shape that gradually decreases in diameter toward the right side (the other end side), and an outer peripheral surface thereof constitutes a second mating surface 24. The second mating surface 24 is a frustoconical surface (conical shape) centered on the rotation axis O1, that is, a tapered surface whose diameter is reduced on the right end side. That is, the outer diameter of the second mating surface 24 is gradually reduced from the left side to the right side.

  Here, in the first embodiment, in a longitudinal sectional view passing through the rotation axis O1, the first inclination angle θ1 of the first mating surface 12 with respect to the rotation axis O1 and the second inclination angle of the second mating surface 24 with respect to the rotation axis O1. It is equal to θ2 (θ1 = θ2, see FIGS. 2B and 3B). The first mating surface 12 and the second mating surface 24 are in close contact with each other over the entire surface.

  A ring-shaped flange 25 is formed on the right side (the reduced diameter portion 22 side) of the large diameter portion 21. The right surface (side surface of the ring gear 10) of the flange 25 forms a flange surface 25a (second opposing surface). The flange surface 25a is flat in a direction that is orthogonal to the rotation axis O1 and has a ring shape. It is a surface and faces the back surface 13 described above.

Further, an annular and concave annular groove 26 (concave portion) is formed on the flange surface 25a so as to face the above-described protrusion 14 and center on the rotation axis O1. The annular groove 26 accommodates the protrusion 14.
An annular protrusion may be formed on the hub member 20 side and an annular groove may be formed on the ring gear 10 side.

≪Power transmission device manufacturing method≫
Next, a method for manufacturing the power transmission device 1 will be described.
The manufacturing method of the power transmission device 1 includes a mating surface forming step for forming a mating surface, a joining step for electrical resistance welding of the ring gear 10 and the hub member 20, and a pressing step for pressing the ring gear 10 and the hub member 20 (upset). Step).

<Mating surface forming process>
As shown in FIG. 3, the first mating surface 12 is formed on the inner circumferential surface of the ring gear 10, and the second mating surface 24 is formed on the outer circumferential surface of the hub member 20. The first mating surface 12 is formed by grinding and polishing the inner peripheral surface of the ring gear serving as a base, for example, with a lathe. The second mating surface 24 is formed by grinding and polishing the outer peripheral surface of the hub member serving as a base, for example, with a lathe.

Moreover, the ring-shaped protrusion 14 and the back surface 13 are formed on the hub member 20 side of the ring gear 10 by grinding or the like. Instead of the ring-shaped protrusions 14, for example, protrusions may be formed at predetermined intervals in the circumferential direction.
On the other hand, an annular groove 26 is formed on the flange surface 25a of the flange 25 of the hub member 20 by grinding or the like.

  Here, the protrusion height of the protrusion 14 from the back surface 13 and the depth of the annular groove 26 from the flange surface 25a are the same as the first mating surface 12 when the ring gear 10 and the hub member 20 are brought close to each other in the axial direction. Before the second mating surface 24 comes into contact, the projection 14 is formed so as to contact and abut the bottom surface 26 a of the annular groove 26. The groove width (radial width) of the annular groove 26 is formed larger than the thickness (radial length) of the protrusion 14 in the radial direction.

<Jointing process (electric resistance welding process)>
The ring gear 10 and the hub member 20 are attached to an electric resistance welder (not shown), and the ring gear 10 and the hub member 20 are relatively close to each other in the axial direction while being arranged on the same rotation axis O1, and the first mating surface. The projection 14 and the bottom surface 26a of the annular groove 26 are abutted with each other by the first pressing force P1 while facing each other while forming a gap between the first mating surface 24 and the second mating surface 24. That is, the annular protrusion 14 is inserted into the annular groove 26, the protrusion 14 is accommodated in the annular groove 26, and the left end of the protrusion 14 and the bottom surface 26 a of the annular groove 26 are in contact with each other.

  The electric resistance welder is, for example, arranged on the right side of the ring gear 10 to push the ring gear 10 leftward and to serve as a first electrode, and on the left side of the hub member 20, the hub member 20. A second jig that pushes right and becomes a second electrode; a power supply device (such as an AC power supply) that supplies a high current for bonding to the first jig and the second jig; and the first jig and the second jig. Pressing means (such as a hydraulic device) that presses the tool in a relatively approaching direction.

  In this manner, with the first mating surface 12 and the second mating surface 24 facing each other with a gap and the projection 14 and the bottom surface 26a butting each other, an electric resistance welder (not shown) is used to connect the ring gear 10 and the hub. The member 20 is energized. Then, the ring gear 10 and the hub member 20 are electrically connected in series to the power supply device, and a high current from the power supply device causes the protrusion 14 and the bottom surface 26a to be interposed between the ring gear 10 and the hub member 20. Will flow only through the butted part.

  Then, as shown in FIGS. 4A and 4B, resistance heat is generated due to energization at the abutting portion where the protrusion 14 and the bottom surface 26a of the annular groove 26 abut each other. The resistance heat softens and melts the protrusion 14 and the bottom surface 26a of the annular groove 26, and the ring gear 10 and the hub member 20 are joined (electrical resistance welding) at the abutting portion.

  At this stage, a slight gap remains between the first mating surface 12 and the second mating surface 24 as shown in FIG.

<Pressing process>
Thereafter, power supply to the ring gear 10 and the hub member 20 is stopped. Then, before the butted portion (joint portion, welded portion) between the protrusion 14 and the bottom surface 26a of the annular groove 26 is completely solidified, the second pressing force P2 (P2> P1) higher than the first pressing force P1 One of the ring gear 10 and the hub member 20 is pressed against the other to bring the ring gear 10 and the hub member 20 relatively close together.

Then, as shown in FIGS. 2A and 2B, the first mating surface 12 and the second mating surface 24 are brought into close contact with each other so that the centers of the ring gear 10 and the hub member 20 coincide with each other. At the same time, at the junction between the projection 14 and the bottom surface 26a of the annular groove 26, impurities intervening between the projection 14 and the annular groove 26 are inside the annular groove 26 and out of the junction. By being pushed out, the joining of the ring gear 10 and the hub member 20 becomes more reliable.
The impurities pushed out to the outside become curled burrs in the annular groove 26 and are not exposed to the outside.

<Other processes>
Thereafter, when the integrated ring gear 10 and the hub member 20 are naturally cooled to room temperature (for example, 25 ° C.), the metal forming the butt portion is solidified to form a joint surface, and the power transmission device 1 is obtained.

≪Effect of manufacturing method of power transmission device≫
According to the manufacturing method of such a power transmission device 1, the following effects are obtained.
Since the 1st mating surface 12 and the 2nd mating surface 24 are frustoconical surfaces centering on the rotation axis O1 after manufacture, the 1st mating surface 12 and the 2nd mating surface 24 contact | adhere by a press process. By doing so, that is, as the ring gear 10 and the hub member 20 are relatively moved closer, the center axis of the ring gear 10 and the center axis of the hub member 20 approach the rotation axis O1 and coincide with each other. Thereby, for example, there is no deviation in meshing between the ring gear 10 and the drive pinion 110.

  In addition, since the first mating surface 12 and the second mating surface 24 are not in contact with each other, and the projection 14 and the bottom surface 26a are in contact with each other, the energization is performed partially, so that the resistance heat is partially generated and the butting portion is efficiently formed. The temperature can be raised. Therefore, electric energy (bonding energy) required for electric resistance welding can be suppressed.

Further, since the burr generated when electric resistance welding is performed on the protrusion 14 is formed in the groove-shaped annular groove 26 of the hub member 20, it does not appear outside the power transmission device 1, but to the gear meshing portion due to the removal of the burr. There is no worry about defects such as biting.
Further, the conventional caulking after press-fitting the spline shaft of the hub member into the link gear becomes unnecessary, and the productivity of the power transmission device 1 is improved.

<< First Embodiment-Modification >>
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this, You may combine suitably with the structure of the form mentioned later, and may be changed as follows. The same applies to the forms described later.

  In the above-described embodiment, as shown in FIG. 3, the ring gear 10 is formed with the annular protrusion 14 (protrusion), and the hub member 20 is formed with the annular ring groove 26 (recess). An annular groove may be formed in 10 and a protrusion may be formed in the hub member 20. Further, an annular groove may be formed on the ring gear 10 in addition to the protrusion 14, and a protrusion corresponding to the annular groove may be formed on the hub member 20 in addition to the annular groove 26.

In the above-described embodiment, the configuration in which the protrusion 14 has an annular shape with the rotation axis O1 as the center has been illustrated. However, for example, a plurality of bosses (projections) may be formed at predetermined intervals in the circumferential direction. . Further, the plurality of bosses (projections) do not have to be arranged on the same circumference, and may be displaced in the radial direction, or may be arranged in a multiple circumference.
In this case, the other-side concave portions of the plurality of bosses may be formed so as to face the bosses. That is, the concave portion does not need to be annular, and may be formed corresponding to the protruding portion.

  In the above-described embodiment, the configuration in which the hub member 20 penetrates the ring gear 10 is illustrated, but a configuration in which the hub member 20 does not penetrate may be used. That is, a conical hole may be formed on the hub member 20 side of the ring gear 10 and the peripheral surface of this hole may be used as the first mating surface.

In the above-described embodiment, the configuration in which the power transmission member is the hub member 20 is illustrated, but the configuration is not limited thereto.
In the above-described embodiment, the configuration in which power is input to the ring gear 10 is illustrated, but a configuration in which power is input to the hub member 20 may be used.

<< Second Embodiment >>
A second embodiment will be described with reference to FIG. In addition, a different part from 1st Embodiment is demonstrated.

A different part is demonstrated about the structure of the power transmission device 1. FIG.
In the second embodiment, no projection 14 (see FIG. 2B) is formed on the back surface 13 of the ring gear 10, and an annular ring groove 15 (first recess) centered on the rotation axis O1 is formed. The ring groove 15 of the ring gear 10 and the ring groove 26 (second recess) of the hub member 20 are arranged to face each other in the axial direction.

The power transmission device 1 according to the second embodiment includes a ring member 41 (joining auxiliary member), and the ring member 41 is formed of an annular groove 15 and an annular groove 26, and has a ring shape centering on the rotation axis O1. It is housed in the space.
The right side portion of the ring member 41 is welded (joined) to the bottom surface 15a (first bottom surface) of the annular groove 15. On the other hand, the left side portion of the ring member 41 is welded (joined) to the bottom surface 26 a (second bottom surface) of the annular groove 26. That is, the ring gear 10 and the hub member 20 are coupled and joined together via the ring member 41.
However, the joining auxiliary member is not limited to a ring shape (annular shape), and may be configured to be divided into a plurality of pieces in the circumferential direction, for example.

A different part is demonstrated about the manufacturing method of the power transmission device 1. FIG.
In the mating surface forming step, the annular groove 15 is formed.

  Next, in the joining step (electrical resistance welding step), the ring member 41 is sandwiched between the annular groove 15 and the annular groove 26, and the bottom surface 15a of the annular groove 15 and the right end surface of the ring member 41 are in contact with each other. The ring gear 10 and the hub member 20 are energized with the bottom surface 26a of the ring 26 and the left end surface of the ring member 41 butted.

  Here, in the axial direction, the thickness of the ring member 41 and the depth of the annular groove 15 and the depth of the annular groove 26 before joining are the same as those of the first mating surface 12 and the second when the ring gear 10 and the hub member 20 are brought close to each other. Before the mating surface 24 comes into contact, the ring member 41 is formed so as to contact and abut against the bottom surface 15a of the annular groove 15 and the bottom surface 26a of the annular groove 26, respectively.

  When energized in this way, a high current is passed through only the first abutting portion between the bottom surface 15a of the annular groove 15 and the ring member 41 and the second abutting portion between the bottom surface 26a of the annular groove 26 and the ring member 41. In the flow, the first butting portion and the second butting portion generate resistance heat due to energization.

  And by this resistance heat, the bottom face 15a of the annular groove 15 and the ring member 41 are softened and melted and joined (electrical resistance welding) at the first abutting portion. On the other hand, in the second butted portion, the bottom surface 26a of the annular groove 26 and the ring member 41 are softened and melted and joined (electrical resistance welding).

«Third embodiment»
A third embodiment will be described with reference to FIG. In addition, a different part from 1st Embodiment is demonstrated.

A different part is demonstrated about the structure of the power transmission device 1. FIG.
As shown in FIGS. 6A and 6B, in the longitudinal sectional view, the first inclination angle θ1 of the first mating surface 12 with respect to the rotation axis O1 and the second angle of the second mating surface 24 with respect to the rotation axis O1. It is different from the inclination angle θ2. Specifically, the first inclination angle θ1 is larger than the second inclination angle θ2 (θ1> θ2). The first mating surface 12 and the second mating surface 24 are in line contact, that is, in circumferential contact in the circumferential direction.

As shown in FIG. 6B, the back surface 13 of the ring gear 10 and the flange surface 25a of the hub member 20 are in close contact (contact) with each other.
Thereby, for example, from the drive pinion 110 (see FIG. 1) with which the ring gear 10 is engaged, in FIG. 6 (a), the front portion of the ring gear 10 is pushed leftward (downward on the paper surface in FIG. 6 (a)). Even if the reaction force is received, the back surface 13 and the flange surface 25a are in close contact with each other, so that the ring gear 10 does not fall with respect to the hub member 20, and the rotation shaft of the ring gear 10 and the rotation shaft of the hub member 20 are shifted. There is nothing.

A different part is demonstrated about the manufacturing method of the power transmission device 1. FIG.
In the pressing step, when the ring gear 10 and the hub member 20 are pressed in the axial direction in a relatively approaching direction, the first mating surface 12 and the second mating surface 24 having different inclination angles are in a linear (circumferential) contact. The center of the ring gear 10 and the center of the hub member 20 coincide with each other, and the pressing force concentrates on the linear contact portion.

Thereby, the ring gear 10 and / or the hub member 20 are elastically deformed or plastically deformed at the contact portion, and the ring gear 10 and the hub member 20 are further brought closer in the axial direction.
Thereafter, when the pressing further proceeds, there is no gap between the back surface 13 and the flange surface 25a, and as shown in FIG. 6B, the back surface 13 and the flange surface 25a are in close contact with each other.

<< Fourth Embodiment >>
A fourth embodiment will be described with reference to FIG. In addition, a different part from 1st Embodiment is demonstrated.

A different part is demonstrated about the structure of the power transmission device 1. FIG.
As shown in FIGS. 7A and 7B, the central portion of the first mating surface 12 protrudes in an arc shape toward the second mating surface 24 in the longitudinal sectional view. The first mating surface 12 and the second mating surface 24 are in line contact, that is, in a circumferential shape in the circumferential direction, as in the third embodiment.
The second mating surface 24 may be arcuate, or both the first mating surface 12 and the second mating surface 24 may be arcuate.

Further, as shown in FIG. 7B, the back surface 13 of the ring gear 10 and the flange surface 25a of the hub member 20 are in close contact (contact) with each other.
Thus, for example, from the drive pinion 110 (see FIG. 1) with which the ring gear 10 is engaged, in FIG. 7 (a), the front side portion of the ring gear 10 is pushed leftward (downward on the page in FIG. 7 (a)). Even if the reaction force is received, the back surface 13 and the flange surface 25a are in close contact with each other, so that the ring gear 10 does not fall with respect to the hub member 20, and the rotation shaft of the ring gear 10 and the rotation shaft of the hub member 20 are shifted. There is nothing.

A different part is demonstrated about the manufacturing method of the power transmission device 1. FIG.
In the pressing step, when the ring gear 10 and the hub member 20 are pressed in the axial direction in a relatively approaching direction, the central portion of the first mating surface 12 and the second mating surface 24 are linear (circumferential) contact portions. The center of the ring gear 10 and the center of the hub member 20 coincide with each other, and the pressing force concentrates on the linear contact portion.

Thereby, the ring gear 10 and / or the hub member 20 are elastically deformed or plastically deformed at the contact portion, and the ring gear 10 and the hub member 20 are further brought closer in the axial direction.
Thereafter, when the pressing further proceeds, there is no gap between the back surface 13 and the flange surface 25a, and the back surface 13 and the flange surface 25a are in close contact with each other as shown in FIG. 7B.

«Fifth embodiment»
A fifth embodiment will be described with reference to FIG. In addition, a different part from 1st Embodiment is demonstrated.

  FIG. 8 is a diagram illustrating a configuration in which the power transmission member is a differential case 230 and the present invention is applied to a final reduction device 200 for a four-wheel vehicle. The final reduction gear 200 includes a drive pinion 210, the ring gear 10, and a differential device 220. The drive pinion 210 is rotatably supported by a case 215 fixed to the vehicle body via bearings 216 and 216. The front end of the drive pinion 210 is connected to the rear end of a propulsion shaft (not shown), and the power of the propulsion shaft is input to the drive pinion 210.

  The gear portion 211 of the drive pinion 210 meshes with the gear portion 11 of the ring gear 10.

  The differential device 220 includes a differential case 230 and a differential gear. The differential gear includes pinion gears 241 and 241 and side gears 242 and 242. The differential case 230 is rotatably supported by a case 235 fixed to the vehicle body via bearings 236 and 236, and the rotation axis O1 is the rotation center of the rear wheel. The power transmission device 2 includes the ring gear 10 and a differential case 230.

  A part of the outer peripheral surface of the differential case 230 has a truncated cone-shaped second mating surface 231 centered on the rotation axis O <b> 1, and the second mating surface 231 is the first mating surface 12 of the ring gear 10. It is in close contact with.

In addition, an annular ring groove 233 is formed in the differential case 230, and the ring groove 233 accommodates the protrusion 14 of the ring gear 10, and the bottom surface of the ring groove 233 is electrically resistance welded to the protrusion 14. That is, the ring gear 10 and the differential case 230 are not fastened by a bolt made of a high-strength material, the number of parts is reduced, and the weight is reduced. That is, in the manufacturing method of the power transmission device 2, the bolt fastening step by the high tightening force between the ring gear 10 and the differential case 230 is unnecessary, and the bolt hole forming step is unnecessary, and the productivity of the power transmission device 2 is improved. Has been improved.
The other functions and effects are the same as those in the first embodiment, and a description thereof will be omitted here.

1, 2 Power transmission device 10 Ring gear (large gear)
12 First mating surface 13 Back surface (first facing surface)
14 Protrusion (protrusion)
15 Ring groove (first recess)
15a Bottom (first bottom)
20 Hub member (power transmission member)
24 2nd mating surface 25a Flange surface (2nd opposing surface)
26 Ring groove (recess, second recess)
26a bottom surface (second bottom surface)
41 Ring member (joining auxiliary member)
100, 200 Final reduction gear 110, 210 Drive pinion 230 Differential case (power transmission member)
231 Second mating surface O1 Rotating shaft

Claims (6)

A manufacturing method of a power transmission device comprising a large gear and a power transmission member, wherein the large gear and the power transmission member are integrally formed and centered on the same rotation shaft,
A conical first mating surface centered on the rotation axis is formed on the large gear, and a conical second mating surface mating with the first mating surface is formed on the power transmission member. A mating surface forming step of forming a projecting portion projecting toward the other on one of the large gear and the power transmission member, and forming a recess facing the projecting portion on the other of the large gear and the power transmission member; ,
With the first mating surface and the second mating surface facing each other, the large gear and the power transmission member are energized in a state where the projecting portion and the bottom surface of the recess are butted, and the projecting portion and the recess A joining process of joining the bottom surface of the metal with electric resistance welding;
A pressing step of pressing the large gear and the power transmission member in a relatively approaching direction in the axial direction to bring the first mating surface and the second mating surface into close contact with each other;
The manufacturing method of the power transmission device characterized by including. A manufacturing method of a power transmission device comprising a large gear and a power transmission member, wherein the large gear and the power transmission member are integrally formed and centered on the same rotation shaft,
A conical first mating surface centered on the rotation axis is formed on the large gear, and a conical second mating surface mating with the first mating surface is formed on the power transmission member. A mating surface forming step of forming a first recess in the large gear and forming a second recess facing the first recess in the power transmission member;
While the first mating surface and the second mating surface are opposed to each other, a joining auxiliary member is sandwiched between the first concave portion and the second concave portion, and the first bottom surface of the first concave portion and the joining auxiliary member are abutted against each other. In a state where the second bottom surface of the second recess and the joining auxiliary member are butted together, the large gear and the power transmission member are energized, and the first bottom surface of the first recess and the joining auxiliary member are A joining step of joining the second bottom surface of the second recess and the joining auxiliary member by electric resistance welding, respectively;
A pressing step of pressing the large gear and the power transmission member in a relatively approaching direction in the axial direction to bring the first mating surface and the second mating surface into close contact with each other;
The manufacturing method of the power transmission device characterized by including. 3. The power according to claim 1, wherein a first inclination angle of the first mating surface with respect to the rotation axis is different from a second inclination angle of the second mating surface with respect to the rotation axis. A method of manufacturing a transmission device. 3. The power transmission device according to claim 1, wherein one of the first mating surface and the second mating surface protrudes in an arc shape toward the other in a longitudinal sectional view. Method. The method of manufacturing a power transmission device according to any one of claims 1 to 4, wherein the power transmission member is a hub member to which a drive wheel is attached. The method of manufacturing a power transmission device according to any one of claims 1 to 4, wherein the power transmission member is a differential case.

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