JP7265282B2 - Friction welding device and friction welding method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a friction welding apparatus and a friction welding method for joining a cast iron member and a steel member by friction welding.

Patent Literature 1 describes that high bonding strength is obtained by preventing or suppressing the formation of a spherical graphite deformed layer. Therefore, Patent Document 1 discloses that an iron-based metal material or a nickel-based metal material is inserted into the pressure contact surface of the spheroidal graphite cast iron in the friction welding of the spheroidal graphite cast iron and the steel material, and the friction welding of the spheroidal graphite cast iron and the steel material. In the above, the pressure contact surface of the spheroidal graphite cast iron has a concave shape; It is described that the pressure contact surface has a concave shape.

Japanese Unexamined Patent Application Publication No. 2002-113583 (summary)

Provided are a friction welding apparatus and a friction welding method capable of manufacturing a joined body having high bonding strength by friction welding.

According to one aspect of the present invention, a first cylindrical wall formed in a cylindrical shape with a first thickness and a first width corresponding to the first thickness on one end side in an axial direction of the first cylindrical wall a first chuck device for gripping a steel member including a first cylindrical portion having a first pressure contact surface formed in an annular shape with and a cylindrical portion having a second thickness greater than the first thickness; and a second pressure contact surface annularly formed with a second width corresponding to the second thickness on one axial end side of the second cylindrical wall. a second chuck device for gripping a cast-iron member including a second cylindrical portion; and a first annular surface formed annularly with the first width and the first pressure contact surface. deformed into a burr surface formed so as to be continuous with the annular surface, the second pressure contact surface deformed into a second annular surface formed annularly with the second width, and the first annular surface The first cylinder of the steel member gripped by the first chuck device such that the entire surface and at least a portion of the burr surface and the second annular surface are joined by friction welding. The friction welding apparatus comprises a drive unit that presses a shaped portion and the second cylindrical portion of the cast iron member gripped by the second chuck device against each other.

According to this friction welding apparatus, a joined body in which a cast iron member and a steel member are joined can be manufactured. In the joined body manufactured by the friction welding apparatus described above, the thickness of the cylindrical portion of the cast iron member is greater than the thickness of the cylindrical portion of the steel member, and the area of the annular surface of the cast iron member is larger than that of the steel member. , the annular surface of the cast iron member can be joined not only to the annular surface of the steel member, but also to the adjacent burr surface. Therefore, the joint area between the cast iron member and the steel member can be made larger than the area of the annular surface of the steel member. Therefore, the joint strength between the cast iron member and the steel member can be improved.

Another aspect of the present invention is a first cylindrical wall formed in a cylindrical shape with a first thickness, and a first cylindrical wall corresponding to the first thickness on one end side in the axial direction of the first cylindrical wall. gripping a steel member including a first cylindrical portion having a first pressing surface formed annularly with a width; and a cylindrically formed portion having a second thickness greater than the first thickness. and a second pressure contact surface annularly formed with a second width corresponding to the second thickness on one axial end side of the second cylindrical wall. By gripping a cast-iron member including a cylindrical portion and pressing the first cylindrical portion and the second cylindrical portion against each other, the first pressure contact surface is widened to the first width. and a burr surface formed so as to be continuous with the first annular surface, and the second pressure contact surface is annularly formed with the second width. a friction welding method comprising: deforming into a second annular surface; and joining the entire first annular surface and at least a portion of the flash surface to the second annular surface by friction welding. is.

Another aspect of the present invention includes a first metal member and a second metal member joined to the first metal member by friction welding and having a melting point lower than that of the first metal member. It is a joined body provided. The first metal member includes a first cylindrical portion having a first cylindrical wall formed in a cylindrical shape with a first thickness, the first cylindrical wall remaining after friction welding. The second metal member is a second cylindrical wall formed in a cylindrical shape with a second thickness greater than the first thickness, the second cylindrical wall having a second cylindrical wall remaining after friction welding. 2 cylinders. The first cylindrical portion is friction-welded with a first annular surface formed annularly with a first width corresponding to the first thickness on one axial end side of the first cylindrical wall. and a burr surface formed contiguously with the first annular surface by burrs produced by. The second cylindrical portion includes a joint surface joined to the first cylindrical portion on one axial end side of the second cylindrical wall. The joint surface is a second annular surface formed annularly with a second width corresponding to the second thickness, and is formed on the entire first annular surface and at least a part of the burr surface. It includes a joined second annular surface.

According to this joined body, the thickness of the cylindrical portion of the second metal member is greater than the thickness of the cylindrical portion of the first metal member, and the area of the annular surface of the second metal member is Being larger than the area of the annular surface of the first metal member, the annular surface of the second metal member can be bonded not only to the annular surface of the first metal member, but also to the burr surface that is continuous therewith. Therefore, the bonding area between the second metal member and the first metal member can be made larger than the area of the annular surface of the first metal member. Therefore, the bonding strength between the first metal member and the second metal member can be improved.

INDUSTRIAL APPLICABILITY A friction welding apparatus and a friction welding method capable of manufacturing a joined body having high bonding strength by friction welding can be provided.

1 is a perspective view showing a joining system using a joining body that is an embodiment of the present invention; FIG. FIG. 2 is a cross-sectional view showing the joining system (cross-sectional view taken along the line II-II in FIG. 1); The perspective view which shows a joined body. FIG. 3 is a cross-sectional view showing a joined body (a cross-sectional view taken along line IV-IV in FIG. 3); FIG. 4 is an end view showing the joined body (end view on line VV in FIG. 4); FIG. 2 is a perspective view showing a state before a cast iron member and a steel member are joined by friction welding; FIG. 6 is a cross-sectional view showing a state before a cast iron member and a steel member are joined by friction welding (cross-sectional view taken along line VII-VII in FIG. 6); Sectional drawing which shows a mode that the member made from cast iron and the member made from steel are joined by friction welding. Fig. 2 is a perspective view showing a state after a cast iron member and a steel member are joined by friction welding;

FIG. 1 shows a perspective view of a joint system 100 using a joint 1 that is an embodiment of the present invention. FIG. 2 shows the joining system 100 in cross-sectional view (cross-sectional view taken along line II-II in FIG. 1). The joining system 100 includes a joined body 1 in which a steel member 10 and a cast iron member 20 are joined by friction welding, and a mechanical joint 90 that mechanically connects adjacent joined bodies 1 to each other. The steel member 10 of this embodiment is a steel pipe 10 , and the cast iron member 20 is a ductile cast iron connector (cast iron connector) 20 mechanically connected to a mechanical joint 90 . The mechanical joint 90 of this embodiment includes a pair of semi-cylindrical covers 91a and 91b that integrally cover the adjacent cast iron connectors 20, and bolts (not shown) that connect the pair of semi-cylindrical covers 91a and 91b together. and a bolt hole (fastening portion) 92 for tightening via a fastening member). Making use of the characteristics of cast iron (casting) that has a high degree of freedom in shape, the cast iron member 20 is made into a cast iron connector 20 that can be mechanically connected to the mechanical joint 90, so that the plurality of steel pipes 10 can be connected without welding. A joint system 100 can be provided.

FIG. 3 shows the joined body 1 in a perspective view. FIG. 4 shows the assembly 1 in a cross-sectional view (a cross-sectional view taken along line IV--IV in FIG. 3). FIG. 5 shows the joined body 1 in an end view (an end view taken along line VV in FIG. 4). As shown in FIGS. 4 and 5, the joint 1 includes a steel pipe 10 and a cast iron connector 20 joined to the steel pipe 10 by friction welding. The steel pipe 10 includes a first cylindrical portion 11 formed in a cylindrical shape with a first thickness t1. The cast iron connector 20 includes a connecting portion 21 for connecting to the mechanical joint 90, and a second cylindrical portion 22 formed cylindrically with a second thickness t2 larger than the first thickness t1, The connecting portion 21 and the cylindrical portion 22 are integrally formed by casting.

The cylindrical portion 11 of the steel pipe 10 has a hollow cylindrical wall 14 extending in the direction of the central axis 11c (axial direction X), and one end (tip) of the cylindrical wall 14 in the axial direction X is provided on one side X1 in the axial direction X. and a first deformation surface 35 formed to face the . The deformed surface 35 is a first pressure contact surface 15 (see FIG. 7) deformed by friction welding, which will be described later. The first annular surface 31 formed in an annular shape (the area sandwiched between imaginary dotted lines L1 and L2 shown in FIG. 5) and the burrs 39 generated by friction welding make the outer peripheral side and the inner peripheral side of the annular surface 31 and a burr surface 32 formed so as to be continuous with.

The burr surface 32 consists of an outer circumferential annular burr surface 32a (a region on the outer circumferential side of the virtual dotted line L1 shown in FIG. 5) formed in an annular shape on the outer circumferential side of the cylindrical portion 11, and an inner peripheral annular burr surface 32b formed in an annular shape on the peripheral side (an area on the inner peripheral side of the imaginary dotted line L2 shown in FIG. 5). The burr 39 of this embodiment includes a curled portion 39c that is bent so that a sharp burr tip 39e faces the other side X2 in the axial direction X, that is, faces the opposite side to the pressure contact direction. The outer peripheral annular burr surface 32a has a shape in which the curled portion 39c of the burr 39 has been removed (deburring process).

The cylindrical portion 22 of the cast-iron connector 20 includes a hollow cylindrical wall 24 extending in the direction of the central axis 22c (axial direction Y) and one end (tip) of the cylindrical wall 24 in the axial direction Y. and a second deformation surface 45 formed to face the side Y1. The deformed surface 45 is a second pressure contact surface 25 (see FIG. 7) deformed by friction welding, and includes a joint surface 45j joined to the cylindrical portion 11 of the steel member 10. FIG. In the present embodiment, the entire deformation surface 45 is the joint surface 45j, but part of the deformation surface 45 may be the joint surface 45j.

The joint surface 45j includes a second annular surface 41 annularly formed with a second width w2 corresponding to the second thickness t2, that is, the same distance as t2. The annular surface 41 is joined to the entire annular surface 31, the entire outer peripheral annular burr surface 32a, and a portion of the inner peripheral annular burr surface 32b (as seen from the virtual dashed line L3 in FIG. 5). is also joined to the outer peripheral region).

According to this joined body 1, the thickness t2 of the cylindrical portion 22 of the cast-iron connector 20 is greater than the thickness t1 of the cylindrical portion 11 of the steel pipe 10, and the area of the annular surface 41 of the cast-iron connector 20 is equal to that of the steel pipe 10. is larger than the area of the annular surface 31 of the . Therefore, the annular surface 41 of the cast iron connector 20 can be joined not only to the annular surface 31 of the steel pipe 10, but also to the outer annular burr surface 32a and the inner annular burr surface 32b connected thereto. Therefore, the area (bonding area) of the joint surface 45j between the cast iron connector 20 and the steel pipe 10 can be made larger than the area of the annular surface 31 of the steel pipe 10 . Therefore, the joint strength between the cast iron connector 20 and the steel pipe 10 can be improved.

As shown in FIGS. 3 and 4, the cast-iron connector 20 has a rough casting surface 20s formed by casting to cover the entire surface, and a casting surface 20s on the outer peripheral side of the cylindrical portion 22. By smoothing the entire of, the outer peripheral side smooth surface (first outer peripheral side smooth surface) 46 remaining in a state of being connected (contacted) with the joint surface 45j after friction welding, and the inner peripheral side of the cylindrical portion 22 By smoothing the entire casting surface 20s, the inner peripheral side smooth surface 47 remains connected (in contact with) the joint surface 45j after friction welding. The casting surface 20s is a surface that retains a rough texture as cast (unprocessed) without peeling off the casting surface (black scale) containing impurities such as oxides. In this embodiment, the outer peripheral smooth surface 46 is continuously formed in the circumferential direction along the outer peripheral surface 22 a of the cylindrical portion 22 , and the inner peripheral smooth surface 47 is formed along the outer peripheral surface 22 a of the cylindrical portion 22 . It is formed continuously without a break in the circumferential direction along the inner peripheral surface 22b. The outer smooth surface 46 and the inner smooth surface 47 are spaced apart from each other by a distance corresponding to the second thickness t2.

In the cast iron connector 20, a part of the cast surface 20s on the outer peripheral side of the connection portion 21, which is close to the steel pipe 10 to be joined, is further smoothed to form a first outer peripheral smooth surface 46. and an outer smooth surface (second outer smooth surface) 48 located adjacent to the . The outer peripheral smooth surface 48 is closer to the cylindrical portion 22 located at the tip of the one side Y1 in the axial direction Y than the end face 21e of the connection portion 21 located at the tip of the other side Y2 in the axial direction Y of the cast iron connector 20. It is arranged at a position close to the deformation surface 45 . The outer peripheral side smooth surface 48 of this embodiment is formed in a perfect circle with respect to the central axis 22c.

According to this joined body 1, the cylindrical portion 22 of the cast-iron connector 20 includes the outer peripheral smooth surface 46 and the inner peripheral smooth surface 47 that remain connected (in contact with) the joint surface 45j after friction welding. Therefore, it is possible to prevent the casting surface 20s from coming into contact with the joint surface 45j. Therefore, impurities contained in the casting surface 20s do not enter the joint surface 45j through the casting surface 20s. Therefore, it is possible to reliably prevent the deterioration of the bonding strength due to the hindrance of the bonding due to the impurities mixed into the bonding surface 45j.

Furthermore, according to this joined body 1, since the outer peripheral smooth surface 46 is in contact with the joint surface 45j, the outer smooth surface 46 of the cast iron connector 20 and the outer peripheral surface 11a of the steel pipe 10 are connected through the joint surface 45j. are connected. Since the outer peripheral surface 11a of the steel pipe 10 is a glossy smooth surface 11a, the joint surface 45j is sandwiched between the smooth surface 46 and the smooth surface 11a that have a common or similar appearance (beauty). Therefore, by making the joint surface 45j inconspicuous, it is possible to provide the dissimilar material joined body 1 in which the joint surface 45j is difficult for a user to visually recognize (recognize). In addition, since the outer smooth surface 48 is arranged adjacent to the outer smooth surface 46, it is possible to further improve the uniformity of appearance.

6 to 9 show an example of joining the cast iron connector 20 and the steel pipe 10 by friction welding. FIG. 6 is a perspective view showing a state before the cast-iron connector 20 and the steel pipe 10 are joined by friction welding, and FIG. 7 is a cross-sectional view showing a state before the cast-iron connector 20 and the steel pipe 10 are joined by friction welding. 8 is a sectional view showing how the cast iron connector 20 and the steel pipe 10 are joined by friction welding, and FIG. 9 is a sectional view showing the cast iron connector 20 and the steel pipe 10. FIG. 4 is a cross-sectional view showing a state after joining by friction welding;

As shown in FIGS. 6 and 7, the cylindrical portion 11 of the steel pipe 10 is annularly formed at one end of the cylindrical wall 14 in the axial direction X with a first width w1 corresponding to the first thickness t1. It includes a first pressure contact surface 15 . The cylindrical portion 22 of the cast-iron connector 20 includes a second pressure contact surface 25 formed in an annular shape with a second width w2 corresponding to the second thickness t2 at one end of the cylindrical wall 24 in the axial direction Y. .

As shown in FIG. 7, the outer peripheral surface 11a of the steel pipe 10 is gripped by a chuck device 50, and the cast iron connector 20 is gripped by a chuck device 60 at the outer peripheral smooth surface (second outer smooth surface) 48. . As a result, the steel pipe 10 and the cast iron connector 20 are arranged coaxially (so that the central axis 11c and the central axis 22c are aligned) so that the pressure contact surface 15 and the pressure contact surface 25 face each other.

Next, as shown in FIG. 8, the cylindrical portion 11 is rotated by a drive unit (not shown) while the cylindrical portion 22 is rotated at high speed around the central axis 22c by a drive unit (not shown). , and the cylindrical portion 11 and the cylindrical portion 22 are joined using frictional heat generated when the pressure contact surface 15 is pressed against the pressure contact surface 25 . Specifically, by controlling parameters such as the rotation speed of the cylindrical portion 22, the pressing force (heating pressure) of the pressure contact surface 15 against the pressure contact surface 25, and the friction time, the joint temperature due to the frictional heat during pressure welding is reduced. Control is performed so that the melting point of the cast iron connector 20 or higher and the steel pipe 10 melting point or lower. As a result, most of the pressure contact surface 25 of the cast iron connector 20 melts due to the frictional heat, disappears while scattering (retreats to the other side Y2 in the Y direction), and most of the pressure contact surface 15 of the steel pipe 10 melts. generates burrs 39 while softening without being melted (plastically deformed).

When the rotation of the cylindrical portion 22 and the pressing (pressurization) of the cylindrical portion 11 are stopped at appropriate timing, the pressure contact surface 25 of the cylindrical portion 22 is deformed into a deformation surface 45 as shown in FIG. , the pressure contact surface 15 of the cylindrical portion 11 is deformed into the deformation surface 35, and the deformation surface 45 and the deformation surface 35 are joined. In this example, the deformation surface 45 is entirely joined to the deformation surface 35, and the deformation surface 45 serves as a joint surface 45j. As a result, a bonded body in which the annular surface 41 of the deformable surface 45, the entire annular surface 31 of the deformable surface 35, a portion of the outer circumferential annular burr surface 32a, and a portion of the inner circumferential annular burr surface 32b are bonded. The bonded body 1 shown in FIGS. 3 and 4 can be provided by deburring the curled portion 39c on the outer peripheral side as necessary. The above is just an example, and the method of friction welding is not limited to this.

In this example, the difference in the melting point between the cast iron connector 20 and the steel pipe 10 is used to plastically deform the steel pipe 10 without melting it, thereby generating an enlarged burr 39 on the steel pipe 10 compared to the cast iron connector 20. The thickness t2 of the cylindrical portion 22 of the cast iron connector 20 is set larger than the thickness t1 of the cylindrical portion 11 of the steel pipe 10 . As a result, the annular surface 41 having a width w2 corresponding to at least the thickness t2 can be joined to the annular surface 31 having a width w1 corresponding to the thickness t1 and the burr surface 32 generated outside thereof. That is, by using the burr surface 32 as a part of the joint surface 45j, the joint area is efficiently increased. Therefore, by increasing only the thickness t2 of the cylindrical portion 22 of the cast iron connector 20 without increasing the thickness t1 of the cylindrical portion 11 of the steel pipe 10, it is possible to improve the joint strength efficiently and at low cost. can. An example of the size of the cylindrical portion 11 and the cylindrical portion 22 is that the thickness t1 of the cylindrical portion 11 is 5 mm and the thickness t2 of the cylindrical portion 22 is 7 mm. The thickness ratio (t2/t1) is 1.4. The thickness ratio is not limited to the above. is preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.6 or less.

In addition, in this example, since the chuck device 60 grips the outer peripheral smooth surface 48 that is arranged closer to the deformation surface 45 side of the cylindrical portion 22 than the end surface 21e of the connecting portion 21, the cylindrical portion 48 is Shaking of the shaft of the shaped portion 22 is easily suppressed. Therefore, the pressure contact surface 15 does not come into contact with the pressure contact surface 25 in a protruded (displaced) state. It can be pressure welded. Furthermore, since the chuck device 60 grips the smooth surface 48 formed in a perfect circle, the alignment (centering) between the central axis 22c of the cylindrical portion 22 and the central axis 11c of the cylindrical portion 11 can be easily performed with accuracy. can do well. Therefore, the annular surface 41, the entire annular surface 31, a portion of the outer annular burr surface 32a, and a portion of the inner annular burr surface 32b can be reliably joined.

The following are examples of features that can be extracted from the specification and drawings. One aspect of the present invention is a joined body comprising a cast-iron member having a rough casting surface formed by casting and a steel member joined to the cast-iron member by friction welding. The steel member includes a first cylindrical portion formed cylindrically with a first thickness, and the cast iron member includes a second cylindrically formed portion with a second thickness greater than the first thickness. including the cylindrical part of The first cylindrical portion is formed to be connected to the first annular surface by a first annular surface having a first width corresponding to a first thickness and a burr generated by friction welding. and the second cylindrical portion includes a mating surface bonded to the first cylindrical portion. The bonding surface is a second annular surface formed annularly with a second width corresponding to the second thickness, and is bonded to the entire first annular surface and at least part of the burr surface. It contains two annular faces.

According to this joined body, the thickness of the cylindrical portion of the cast iron member is greater than the thickness of the cylindrical portion of the steel member, and the area of the annular surface of the cast iron member is greater than the area of the annular surface of the steel member. is large, the annular surface of the cast iron member can be joined not only to the annular surface of the steel member, but also to the adjacent burr surface. Therefore, the joint area between the cast iron member and the steel member can be made larger than the area of the annular surface of the steel member. Therefore, the joint strength between the cast iron member and the steel member can be improved.

It is preferable that the second cylindrical portion include an outer peripheral smooth surface that remains connected to the joint surface after friction welding by smoothing a part of the casting surface on the outer peripheral side. Since the outer smooth surface from which the casting surface containing impurities such as oxides has been removed remains connected to the joint surface, it is possible to reduce the probability that impurities are mixed into the joint surface. For this reason, it is more preferable that the outer peripheral side smooth surface is formed continuously in the circumferential direction of the second cylindrical portion. It is possible to further reduce the probability that impurities are mixed into the joint surface from the outer peripheral side of the cylindrical portion of the cast iron member. Therefore, it is possible to suppress the deterioration of the bonding strength due to the hindrance of bonding due to the contamination of the bonding surfaces with impurities.

It is preferable that the second cylindrical portion include an inner peripheral smooth surface that remains connected to the joint surface after friction welding by smoothing a part of the inner peripheral casting surface. Since the inner peripheral smooth surface from which the casting surface has been removed remains connected to the joint surface, it is possible to reduce the probability that impurities are mixed into the joint surface. Therefore, it is more preferable that the inner peripheral smooth surface is formed continuously in the circumferential direction of the second cylindrical portion. It is possible to further reduce the probability that impurities are mixed into the joint surface from the inner peripheral side of the cylindrical portion of the cast iron member.

The burr surface includes an outer circumferential annular burr surface formed annularly on the outer circumferential side of the first cylindrical portion and an inner circumferential annular burr surface formed annularly on the inner circumferential side of the first cylindrical portion. Preferably, the second annular surface is joined to the entire first annular surface, at least part of the outer annular burr surface, and at least part of the inner annular burr surface. The annular surface of the cast iron member may be joined to the annular burr surface on one side (one of the outer circumference and the inner circumference) of the steel member, but the annular burrs on both sides (both the outer circumference and the inner circumference) By being joined to the surfaces, the joint area between the cast iron member and the steel member can be increased, and the joint strength can be further improved.

Another aspect of the present invention is a joining system comprising the joining bodies described above and a mechanical joint for mechanically connecting the joining bodies adjacent to each other. Typically, the steel member is a steel pipe from which the first cylindrical portion extends and the cast iron member is a connector mechanically connectable to the mechanical joint. By using a cast iron member with a high degree of freedom in shape as a connector that can be mechanically connected to a mechanical joint, it is possible to provide a joint system with high joint strength in which a plurality of steel pipes are connected without welding.

REFERENCE SIGNS LIST 1 joined body 90 mechanical joint 100 joining system 10 steel member (steel pipe) 11 first cylindrical portion 14 cylindrical wall 15 first pressure contact surface 20 cast iron member (cast iron connector) 20s Casting surface 21 Connecting portion 22 Second cylindrical portion 24 Cylindrical wall 25 Second pressure contact surface 31 First annular surface 32 Burr surface 32a Outer peripheral annular burr surface 32b Inner peripheral annular burr surface 35 first deformed surface 39 burr 39c curled portion 41 second annular surface 45 second deformed surface 45j joining surface 46 first outer smooth surface 47 inner smooth surface surface 48 second outer smooth surface 50, 60 chuck device t1 first thickness t2 second thickness w1 first width w2 second width

Claims (2)

a first cylindrical wall formed in a cylindrical shape with a first thickness; and a first cylindrical wall formed in an annular shape with a first width corresponding to the first thickness on one end side of the first cylindrical wall in the axial direction. a first chuck device for gripping a steel member including a first cylindrical portion having a pressure contact surface;
a second cylindrical wall formed in a cylindrical shape with a second thickness greater than the first thickness; and a second cylindrical wall corresponding to the second thickness on one axial end side of the second cylindrical wall. a second chuck device for gripping a cast iron member including a second cylindrical portion having a second pressure contact surface formed in a width and annular shape;
The first pressure contact surface deforms into a first annular surface formed in an annular shape with the first width and a burr surface formed so as to be continuous with the first annular surface, and the second pressure contact surface is formed. is transformed into a second annular surface formed annularly with the second width, and the entire first annular surface and at least a portion of the burr surface and the second annular surface The first cylindrical portion of the steel member gripped by the first chucking device and the first cylindrical portion of the cast iron member gripped by the second chucking device are joined by friction welding. 2, and a drive unit that presses the two cylindrical parts against each other in a state where the joint temperature due to frictional heat during friction welding is above the melting point of the cast iron member and below the melting point of the steel member. a first cylindrical wall formed in a cylindrical shape with a first thickness; and a first cylindrical wall formed in an annular shape with a first width corresponding to the first thickness on one end side of the first cylindrical wall in the axial direction. grasping a steel member including a first cylindrical portion having a pressure contact surface;
a second cylindrical wall formed in a cylindrical shape with a second thickness greater than the first thickness; and a second cylindrical wall corresponding to the second thickness on one axial end side of the second cylindrical wall. gripping a cast iron member including a second cylindrical portion having a second pressure contact surface annularly formed with a width;
The first cylindrical portion and the second cylindrical portion are pressed against each other in a state in which the joint temperature due to frictional heat during friction welding is equal to or higher than the melting point of the cast iron member and equal to or lower than the melting point of the steel member. As a result, the first pressure contact surface is deformed into a first annular surface formed in an annular shape with the first width and a burr surface formed so as to be continuous with the first annular surface. is deformed into a second annular surface annularly formed with the second width, and all of the first annular surface and at least part of the burr surface and the second annular surface and joining the surfaces by friction welding.

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