JP2006150397A - Ring projection welding method and ring projection welding member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a ring projection welding method and a ring projection welding member which enable both external and internal tubes to be fully joined, by avoiding incomplete welding due to insufficient fusion of a contact part or generation of surface flash, in joining an end face of a multilayered tube member with some other member. <P>SOLUTION: In the projection welding method between each end face of the internal and the external tube of a multilayered tube member as one part and some other member as the other part, the multilayered tube member has the internal tube and the external tube that encloses the internal tube. Before the welding, the sum (Sc) of the burn-off length cross section of the projections formed at least either on the internal tube end face or on the part corresponding thereto of the other member is made smaller than the sum (Sd) of the burn-off length cross section of the projections formed at least either on the external tube end face or on the part corresponding thereto of the other member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a ring projection welding method and a ring projection welding member for welding and joining an end surface of a multiple pipe member and another member, and more specifically, a piston for an internal combustion engine, an exhaust manifold, a water supply pipe, and a hydraulic piston having a multiple pipe shape. The present invention relates to a ring projection welding method and a projection welding member suitable for the above.

  For example, as disclosed in Japanese Patent Application Laid-Open No. H10-228707, the end face of a multi-pipe member such as a double pipe and another member may be welded together by friction welding. FIG. 7 is a cross-sectional view of a part of a piston 70 for an internal combustion engine having a double pipe shape, which is disclosed in Patent Document 1 and joined and integrated by friction welding. In FIG. 7, the piston 70 for an internal combustion engine is forged by dividing the top land portion 71 and the skirt portion 72 by a metal material having good strength and machinability, and has good heat resistance around the opening of the cavity 70e. A ring member 70L made of metal is forged and joined, and the top land portion 71 and the skirt portion 72 are joined by friction welding at the joining surfaces 70c and 70d. The internal combustion engine piston 70 has a double pipe shape having an inner pipe 72a and an outer pipe 72b with a cooling channel 70w interposed therebetween. In addition, 70g is a ring groove where a piston ring is mounted. According to Patent Document 1, an internal combustion engine piston suitable for a high-power internal combustion engine as compared with a cast piston can be obtained.

  On the other hand, the welding joint between the end face of the multiple tube member and the other member can be performed by ring projection welding as disclosed in, for example, Patent Document 2. FIG. 8 shows a closed-cavity type piston having a double-pipe shape, which is joined and integrated by ring projection welding, disclosed in Patent Document 2, and (a) shows a piston body 81 and a piston cap 82 before welding. Each sectional view and (b) are sectional views of the closed cavity type piston 80 after welding. As shown in FIG. 8 (a), before welding, the cylindrical piston body 81 is formed with a projection 81c having a V-shaped cross section on the end surface of the annular inner tube 81a, and also includes an inner tube 81a. A projection 81d having a V-shaped cross section is formed on the end face of the outer tube 81b. The piston cap 82 is formed with an annular flat contact portion 82c at a portion corresponding to the projection 81c of the inner tube 81a of the piston body 81, and at a portion corresponding to the projection 81d of the outer tube 81b of the piston body 81. An annular flat contact portion 82d is formed. Then, the projections 81c and 81d of the piston body 81 and the contact portions 82c and 82d of the piston cap 82 are brought into contact with each other, and the projection is melted and weld-bonded by press-bonding them while passing a high current. 8B, after welding, the projection 81c of the inner pipe 81a of the piston body 81 and the contact portion 82c of the piston cap 82 are joined, and the projection 81d of the outer pipe 81b of the piston body 81 A contact portion 82d of the piston cap 82 is joined to form a closed cavity type piston 80 having a double tube shape. According to Patent Document 2, an accurate amount of energy necessary for welding can be supplied to each projection (81c, 81d) and contact portion (82c, 82d), and the generated heat is concentrated in a narrow region. The joint surfaces 80c and 80d after welding are strong and increase in strength, and are heated slightly, so there is almost no heat conduction and deformation, and further, the welding can be repeated accurately, so that the reliability is improved. .

JP 2001-82247 A JP 2004-92636 A

  However, the piston 70 for an internal combustion engine welded and joined by friction welding as shown in FIG. 7 disclosed in Patent Document 1 is a concentric circle with respect to the rotating shaft 70s when the joint surfaces 70c and 70d are friction welded. It is necessary to make the shape, and the degree of freedom of the shape of the joint surfaces 70c and 70d is small. Depending on the shape of the cooling channel 70w of the piston 70 for the internal combustion engine, it is also required that the split surfaces 70c and 70d have a complicated shape rather than a concentric circular shape. In such a case, it is difficult to weld and join by friction welding. is there. Also, in welding joining by friction welding, either the top land portion 71 or the skirt portion 72 is rotated and pressed against each other with a constant friction pressure for a predetermined time, thereby causing the joining surfaces 70c and 70d to generate heat by friction to a high temperature. After that, it is necessary to suddenly stop the rotation and apply an upset pressure and hold it for a certain period of time for bonding. Therefore, the internal combustion engine piston 70 to be welded by friction welding requires a lot of time from the start to completion of the joining, which is disadvantageous in terms of manufacturing cost.

  On the other hand, when the closed cavity type piston 80 disclosed in Patent Document 2 as shown in FIG. 8 is joined by ring projection welding, there is a problem that the degree of freedom of the shape of the joining surface which is a problem in the friction welding is small. The problem of a long time from the start to completion of joining can be avoided. However, the V-shaped projections 81c and 81d are simply formed on the inner tube 81a and the outer tube 81b of the piston body 81, respectively, flat contact portions 82c and 82d are formed on the piston cap 82, and then ring projection welding is performed. In this case, although the joining of the joining surface 80d of the outer tube 81b is good, the joining surface 80c of the inner tube 81a may not be completely joined due to insufficient melting due to the small amount of heat generated by the projection 81c. If the joining surface 80c of the tube 81a is to be completely joined, the joining surface 80d of the outer tube 81b may not be completely joined because the amount of heat generated by the projection 81d is so large that so-called scattering occurs.

  Therefore, the object of the present invention is to melt the projection in the welding joint between the end face of the multi-pipe member and another member, such as the internal combustion engine piston 70 shown in FIG. 7 or the closed cavity type piston 80 shown in FIG. An object of the present invention is to obtain a ring projection welding method and a ring projection weld member capable of avoiding incomplete weld joints due to insufficient or scattering.

  When joining the end face of a multi-pipe member such as a double pipe and another member by ring projection welding, the inventors have insufficient melting due to the difference in the amount of heat generated in the projection of the inner pipe and the outer pipe. The present inventors have found that the problem of scattering can be solved by appropriately adjusting the size of the projection formed in advance on the joint surface.

  That is, the projection welding method of the present invention is a ring projection welding method of a multi-tube member having an inner tube and an outer tube enclosing the inner tube, and the respective end surfaces of the inner tube and the outer tube and other members. The sum (Sc) of the marginal cross sectional area of the projection formed on at least one of the end surface of the inner tube and the portion corresponding to the end surface of the inner tube on the other member is the outer tube. It is characterized by being formed smaller than the sum (Sd) of the marginal cross sectional area of the projection formed on at least one of the end surface and the portion corresponding to the end surface of the outer tube on the other member.

  Here, the above-mentioned cross sectional area is the cross sectional area of the section where the projection is pressed and deformed before and after joining in the axial section of the multiple pipe and the height of the projection (length in the multiple pipe axial direction) is reduced. Say. That is, when the double pipe 12 and the other member 11 as shown in FIG. 1A are welded and joined, the projections 12d and 12c before joining are added as shown in FIG. 1D after joining. It is deformed by the pressure and the height of the H portion is reduced. The area (shaded portion) of the height H portion of the projection shape before joining is referred to as a cross sectional area. Then, the sum (Sc) of the cross sectional area of the projection formed on at least one of the end surface of the inner tube and the portion corresponding to the end surface of the inner tube on the other member is the end surface of the outer tube and the other In order to make it smaller than the sum (Sd) of the proximate sectional area of the projection formed on at least one of the portions corresponding to the end face of the outer tube on the member, the multiple tube axial section of the projection For example, when the shape of the projection in the double tube axis direction is substantially V-shaped as shown in FIG. 1, the tip of the projection is shown in FIG. It is preferable that the width (Td, Tc) at an arbitrary distance from is such that Td> Tc. Moreover, not only a substantially V-shape but also a rectangle, a U-shape, a kana-letter shape, and a kanji-like convex shape can be similarly defined.

  Further, the projection may be formed only on the end face of the multi-pipe member 12 as shown in FIG. 1, or conversely, it may be formed only on the other member 11 as shown in FIG. It may be formed in both as shown in (d). Furthermore, as shown in FIG. 2 (b), the projection may be formed only on the end surface of the outer tube of the multi-pipe member and the portion corresponding to the end surface of the inner tube of the other member. As shown in (2), it may be formed only on the end surface of the inner tube of the multiple tube member and the portion corresponding to the end surface of the outer tube of the other member. Further, the other member 11 may be a multiple tube member. Then, the marginal cross sectional area (Sc) of the projection formed on the end surface of the inner tube or the end surface of the inner tube on the other member corresponds to the end surface of the outer tube or the end surface of the outer tube on the other member. The projection is formed so as to be smaller than the cross sectional area (Sd) of the projection formed at the portion.

  More specifically, when the projection is formed only on the end face of the multi-pipe member 12 as shown in FIG. 1, the marginal sectional area (Sc) of the projection 12c is changed to the marginal sectional area (Sd) of the projection 12d. It is shaped to be smaller. Further, when the projection is formed only on the other member 11 as shown in FIG. 2A, the marginal sectional area (Sc) of the projection 11c is smaller than the marginal sectional area (Sd) of the projection 11d. It is molded as follows. Further, as shown in FIG. 2B, a projection 12d is formed on the end surface of the outer tube 12b of the multiple tube member 12, and a projection 11c is formed on a portion corresponding to the end surface of the inner tube 12a on the other member 11. In this case, the marginal sectional area (Sc) of the projection 11c is formed to be smaller than the marginal sectional area (Sd) of the projection 12d. 2D, when the projection is formed on both the end surface of the multi-pipe member 12 and the other member 11, the marginal sectional area of the projection 11c and the marginal sectional area of the projection 12c (Sc) is smaller than the sum (Sd) of the marginal sectional area of the projection 11d and the marginal sectional area of the projection 12d.

  By setting it as the said structure, the emitted-heat amount of the projection formed in the site | part corresponding to the end surface of the inner tube at the time of ring projection welding, or the end surface of the inner tube on another member can be enlarged. Although this reason is not clear, it can be estimated as follows. That is, a projection formed on at least one of the end surface of the inner tube and the portion corresponding to the end surface of the inner tube on the other member (hereinafter referred to as “the end surface of the inner tube and the end surface of the inner tube on the other member”). The sum of the proximate cross-sectional areas of the projections formed on at least one of the portions corresponding to “the inner projection” corresponds to the end surface of the outer tube and the end surface of the outer tube on the other member. A projection formed on at least one of the parts (hereinafter referred to as “a projection formed on at least one of the end face of the outer tube and the part corresponding to the end face of the outer pipe on another member”) In the case of ring projection welding, the current that flows instantaneously flows more to the outer tube than the inner tube due to the skin effect, The current flowing through the inner tube is reduced. As a result, the current density of the inner projection is smaller than the outer projection, and the amount of heat generation is also smaller. Therefore, by forming the sum of the marginal cross-sectional areas of the inner projection to be smaller than the sum of the marginal cross-sectional areas of the outer projection, it is possible to increase the current density of the inner projection and increase the heat generation amount. Reduces the difference in heat generation between the inner and outer projections, avoids inadequate melting of the joint surface of the inner tube, and avoids scattering on the joint surface of the outer tube. It can be completely joined to other members.

  Here, the multiple tube member is not limited to a double tube shape, but includes a triple tube or more.

  In the projection welding method of the present invention, the sum of the marginal sectional areas of the projections formed on at least one of the end surface of the inner tube and the portion corresponding to the end surface of the inner tube on the other member ( Sc), and when the sum of the marginal cross sectional area of the projection formed on at least one of the end surface of the outer tube and the portion corresponding to the end surface of the outer tube on the other member is (Sd), (Sc / Sd) is preferably 0.4 to 0.9. In the above configuration, when (Sc / Sd) is 0.9 or less, the calorific value of the inner projection is more reliably increased, and the calorific value of the outer projection is comparable to that of the outer projection without causing insufficient melting. The inner pipe is more securely welded. On the other hand, when (Sc / Sd) is set to 0.4 or more, the heat generation amount of the inner projection does not rise abnormally, and welding without occurrence of scattering can be performed. By avoiding the occurrence of insufficient melting and scattering as described above, when ring projection welding is applied to a welded member that receives high stress, the strength of the joint surface is improved, and a highly reliable welded member as a high-strength part Can be obtained. A more preferable range of (Sc / Sd) is 0.6 to 0.8.

  In addition, a ring projection welding member according to another aspect of the present invention includes a multi-tube member having an inner tube and an outer tube containing the inner tube, the respective end faces of the inner tube and the outer tube, and other members. Of the projection formed on at least one of the end surface of the inner tube and the portion corresponding to the end surface of the inner tube on the other member. A multi-tube member formed such that the sum is smaller than the sum of the marginal cross sectional areas of projections formed on at least one of the end surface of the outer tube and the portion corresponding to the end surface of the outer tube on the other member; The other member is welded and joined by ring projection welding. By setting it as the said structure, the ring projection welding member by which the welding part of each end surface of the inner tube of the multiple tube member and the outer tube and the other member was joined completely can be obtained.

  In the present invention, the ring projection welding member may be an internal combustion engine piston, and the multiple pipe member may be one or both of the internal combustion engine piston divided into an upper part and a lower part. After the internal combustion engine piston is manufactured independently at the upper and lower parts so as to have the above-mentioned projection, it is joined by ring projection welding to form an integrated internal combustion engine piston, so that the welding surface is completely joined. A piston for an internal combustion engine having a high joint surface strength can be obtained.

  Alternatively, in the present invention, the ring projection welding member may be an exhaust manifold, and the multiple pipe member may be a branch pipe in which a part of the exhaust manifold is divided into a mounting flange and a branch pipe. After producing each of the exhaust manifold mounting flange and branch pipe so as to have a projection of the above-described configuration on at least one of the joint surfaces, welding is performed by ring projection welding to form an integrated exhaust manifold. An exhaust manifold can be obtained in which the surfaces are completely joined and no gas leaks from the joined surfaces.

  According to the ring projection welding method and the ring projection welding member of the present invention, in the joining of the end face of the multiple tube member and the other member, incomplete welding joining due to insufficient melting or scattering of the projection. It can be avoided.

Hereinafter, several examples of embodiments of the present invention will be described in detail with reference to the drawings.
(Embodiment 1)
FIG. 1 is an explanatory view of a multiple pipe member in the form of ring projection welded double pipe and its welding method according to the first embodiment, and FIG. 1 (a) shows the multiple pipe member 12 and others before welding joining. Sectional view of member 11, (b) is an enlarged view of part A in (a), (c) is a sectional view of welded member 10 after joining, and (d) is an enlarged view of the joined part in (c). . 1A and 1B, the other member 11 is made of a (JIS) SCM415 material, has an outer diameter of 90 mm, and has a flat bottom surface. On the other hand, the multi-tube member 12 is made of (JIS) SCM415 material, and has an inner tube 12a having an inner diameter (Dci) of 47 mm and an outer diameter (Dco) of 54 mm, and an inner diameter (Ddi) of 70 mm. A projection 12c having an outer tube 12b, having a substantially V-shaped cross section is formed on the end surface of the inner tube 12a, and a projection 12d having a substantially V-shaped cross section is also formed on the end surface of the outer tube 12b. A flat portion having a width of 0.5 mm is formed at the top of each projection 12c, 12d of the multiple tube member. Then, the marginal sectional area Sc (area shown by the mesh in FIG. 1D) of the projection 12c of the inner tube 12a of the multiple tube member is adjusted by adjusting Td and Tc shown in FIG. The cross sectional area Sd of the projection 12d of the tube 12b (the area indicated by the mesh in FIG. 1D) is formed so that the area ratio is 0.8.

  Next, the other member 11 and the multiple tube member 12 are mounted on a joining jig (not shown) provided in the ring projection welder, and the voltage is 420 to 450 V, the capacitor capacity is 1.5 to 1.8 F, Joining is performed by ring projection welding under welding conditions of a pressure of 130 to 150 kN and an energization time of 50 ms (milliseconds). In this ring projection welding, welding can be performed without causing insufficient melting or scattering of the projection.

(Embodiment 2)
FIG. 3 is an explanatory view of a ring projection welded piston for an internal combustion engine and a welding method thereof according to the second embodiment, and FIG. 3 (a) shows that the piston for the internal combustion engine is separated into an upper part and a lower part at a cooling channel part. Each sectional view of the piston upper part 21 and the piston lower part 22 after being manufactured independently and before joining by ring projection welding, (b) is the piston upper part 21 and piston on the joining jig (JIG) just before joining. Each sectional view of the lower portion 22 is a sectional view of the piston 20 for the internal combustion engine after joining. 4 is an enlarged view of the main part of FIG. 3, (a) is an enlarged sectional view of the piston upper part 21 and the piston lower part 22 before joining, and (b) is an enlarged view of the projections 22c and 22d in (a). (C) is the expanded sectional view of piston 20 for internal combustion engines after joining. 3 and 4, the piston upper portion 21 is made of (JIS) SCM415 material, and has an inner tube 21a having an outer diameter of 54 mm and an outer tube 21b having an inner diameter of 70 mm that encloses the inner tube 21a. A contact portion 21c having a flat cross section exists on the end surface of the tube 21a, and a contact portion 21d having a flat cross section also exists on the end surface of the outer tube 21b. On the other hand, the piston lower part 22 is made of (JIS) SCM415 material, and has an inner tube 22a having an outer diameter of 54 mm and an outer tube 22b having an inner diameter of 70 mm containing the inner tube 22a. Forms a substantially V-shaped projection 22c, and a projection 22d having a substantially V-shaped cross section is also formed on the end face of the outer tube 22b. Moreover, as shown in FIG.4 (b), the flat part of width 0.5mm is formed in the top part of each projection 22c, 22d of the piston lower part 22. As shown in FIG. Then, the marginal cross sectional area Sc (shown by mesh) of the projection 22c of the inner pipe 22a of the piston lower portion 22 is 0. 0 in terms of the area ratio with respect to the marginal cross sectional area Sd (shown by mesh) of the projection 22d of the outer pipe 22b. It is formed by adjusting Td and Tc to be 87.

  As shown in FIG. 3B, the piston upper part 21 and the piston lower part 22 are attached to a joining jig (JIG) provided in a ring projection welder (not shown), and then the piston upper part 21 and the piston lower part 22 are attached. The lower projection 22 is brought into contact, and ring projection welding is performed under welding conditions of a voltage of 420 to 450 V, a capacitor capacity of 1.5 to 1.8 F, a pressing force of 130 to 150 kN, and an energization time of 50 ms (milliseconds). In this ring projection welding, welding can be performed without causing insufficient melting or scattering of the projection.

(Embodiment 3)
FIG. 5 is an explanatory view of a branch pipe and a mounting flange of a ring projection welded double pipe structure and a welding flange according to the third embodiment, and a welding joining method thereof. FIG. FIG. 5B is a cross-sectional view of a part of the front branch pipe and the mounting flange, FIG. 5B is an enlarged cross-sectional view of the projections 52c and 53d, and FIG. 5C is a cross-sectional view of a part of the exhaust manifold after joining. 5A, the mounting flange 51 has contact portions 51c and 51d on the same plane on the left side in the drawing. On the other hand, the branch pipe includes an inner pipe 52 and an outer pipe 53 that encloses the inner pipe. A projection 52c having a substantially V-shaped cross section is formed on the end face of the inner pipe 52, and a cross section is also formed on the end face of the outer pipe 53. A substantially 53-shaped projection 53d is formed. Further, as shown in FIG. 5B, a flat portion having a width of 0.2 mm is formed at the top of each projection 52c, 53d. The marginal sectional area of the projection 52c of the inner tube 52 is formed by adjusting Td and Tc so that the area ratio is 0.8 with respect to the marginal sectional area of the projection 53d of the outer tube 53. .

  The mounting flange 51, the inner tube 52, and the outer tube 53 are attached to a joining jig provided in a ring projection welder (not shown), and ring with a predetermined voltage, capacitor capacity, applied pressure, and energization time. Projection welding. After ring projection welding, as shown in FIG. 5 (c), the mounting flange 51, the inner tube 52 and the outer tube 53 are joined together by forming a heat retaining space 50g with the joining surface 50c and the joining surface 50d. The In this ring projection welding, welding can be performed without causing insufficient melting and scattering of the projection.

(Embodiment 4)
FIG. 6 shows an explanatory diagram of a ring projection welded water pipe 60 and its welding method according to the fourth embodiment. FIG. 6A shows an inner pipe 61, an outer pipe 62, a female joint 63, and a male joint 63 before joining. Each sectional view in which the middle of the joint 64 is omitted, (b) is a sectional view in which the projections 61c and 62d are enlarged, and (c) is a sectional view of the water supply pipe 60 in which the middle after joining is omitted. In FIG. 6A, the inner tube 61 is made of stainless steel, and a projection 61c having a substantially V-shaped cross section is formed on an end surface having an outer diameter of 60 mm and a thickness of 5 mm. Further, the outer tube 62 made of stainless steel, which is slightly longer than the inner tube 61 and encloses the inner tube 61 concentrically, has a projection 62d having an outer diameter of 90 mm and a wall thickness of 5 mm on the end surface of a substantially V-shaped section. Is formed. The female joint 63 on the right side in FIG. 6 (a) is made of stainless steel, and the contact portions 63c and 63d having a flat cross section are present at portions corresponding to the respective 61c and 62d of the inner tube 61 and the outer tube 62. Yes. The marginal sectional area of the projection 61c of the inner pipe 61 is formed by adjusting Td and Tc so that the area ratio is 0.8 with respect to the marginal sectional area of the projection 62d of the outer pipe 62. Yes. In addition, 60p is a water supply part.

  The inner tube 61, the outer tube 62, and the joint 63 are attached to a joining jig provided in a ring projection welder (not shown), and ring projection welding is performed with a predetermined voltage, capacitor capacity, pressure, and energization time. Has been. Similarly, the left male joint 64 in FIG. 6A is also ring projection welded to the inner tube 61 and the outer tube 62.

  After ring projection welding, as shown in FIG. 6C, the inner pipe 61, the outer pipe 62, the female joint 63, and the male joint 64 are integrally joined to form a water supply pipe having a heat retaining space 60g. In this ring projection welding, welding can be performed without causing insufficient melting and scattering of the projection.

  In the internal combustion engine piston 20 shown in FIG. 3 and FIG. 4, the ratio of the marginal sectional area Sc of the projection 22c of the inner tube 22a of the lower piston 22 to the marginal sectional area Sd of the projection 22d of the outer tube 22b (Sc / Sd) was changed, ring projection welding was performed under welding conditions of a voltage of 420 V, a capacitor capacity of 1.5 F, a pressing force of 130 kN, and an energization time of 50 ms (milliseconds), and after joining, each including a joining surface 20c and a joining surface 20d was 10 mm. A test piece for a tensile test of × 35 mm × thickness of 3.0 mm was cut out and evaluated by measuring the tensile strength. Tensile strength was evaluated as (◯) when 700 MPa or more, (Δ) when 650 MPa or more and less than 700 MPa, and (x) when less than 650 MPa. The results are shown in Table 1.

(Table 1)
No. Cross-sectional area ratio (Sc / Sd) tensile strength evaluation
Junction 20c Junction 20d
Example 1 0.35 △ ○
Example 2 0.40 ○ ○
Example 3 0.65 ○ ○
Example 4 0.80 ○ ○
Example 5 0.85 ○ ○
Example 6 0.90 ○ ○
Example 7 0.95 △ ○
Comparative Example 1 1.00 × ○

  As shown in Table 1, in Examples 1 to 7, the marginal sectional area Sc of the projection 22c of the inner tube 22a is made smaller than the marginal sectional area of the projection 22d of the outer tube 22b. The determination of strength was (◯), and the determination of the tensile strength of the joint 20c was (◯) or (Δ). Particularly in Examples 2 to 6, the ratio (Sc / Sd) of the marginal sectional area Sc of the projection 22c of the inner tube 22a and the marginal sectional area Sd of the projection 22d of the outer tube 22b is 0.4 to 0.9. Therefore, all the determinations of the tensile strength were (◯), and even better results were obtained. On the other hand, in Comparative Example 1, since the value of (Sc / Sd) was set to 1.00, the amount of heat generated at the joint 20c was insufficient, so that the joining was incomplete, and the determination of the tensile strength of the joint 20c was (x). .

The explanatory drawing of the double pipe shape member and its welding method which were ring projection welded based on Embodiment 1 is shown, (a) is sectional drawing of each member 11 and 12 before joining, (b) is (a). (C) is sectional drawing of the welding member 10 which has the double pipe shape after joining, (d) is an enlarged view of the junction part in (c). FIG. 2 is a diagram showing another formation position of the projection with respect to FIG. FIG. 5 shows explanatory views of a ring projection welded piston for an internal combustion engine and a welding method thereof according to Embodiment 2, wherein (a) is a sectional view of the piston upper part 21 and the piston lower part 22 before joining, and (b) is a joined part. Each sectional view of the piston upper part 21 and the piston lower part 22 on the immediately preceding joining jig (JIG), (c) is a sectional view of the piston 20 for the internal combustion engine after joining. 3 shows an enlarged view of the main part of FIG. 3, (a) is an enlarged sectional view of the piston upper part 21 and the piston lower part 22 before joining, (b) is a sectional view further enlarging the projections 22c, 22d in (a), (C) is an enlarged sectional view of the piston 20 for an internal combustion engine after joining. FIG. 6 is an explanatory view of an exhaust manifold welded by ring projection and its welding method according to the third embodiment, (a) is a sectional view of a part of a branch pipe and a mounting flange before joining, and (b) is (a). FIG. 5C is an enlarged cross-sectional view of the projections 52c and 53d in FIG. 5, and FIG. The explanatory drawing of the water pipe 60 and its welding method by which ring projection welding based on Embodiment 4 is shown, (a) is the intermediate | middle of the inner pipe 61, the outer pipe 62, the female joint 63, and the male joint 64 before joining. (B) is an enlarged cross-sectional view of the projections 61c and 62d in (a), and (c) is a cross-sectional view of the water supply pipe 60 with the middle after joining omitted. FIG. 6 is a cross-sectional view of a part of a piston 70 for an internal combustion engine having a double pipe shape, which is disclosed in Patent Document 1 and joined and integrated by friction welding. FIG. 2 shows a closed cavity type piston having a double pipe shape, which is joined and integrated by ring projection welding, disclosed in Patent Document 2, wherein (a) is a sectional view of a piston body 81 and a piston cap 82 before welding; (B) is sectional drawing of the obstruction | occlusion cavity type piston 80 after welding.

Explanation of symbols

10: Welding member 10c, 10d, 20c, 20d, 50c, 50d, 60c, 60d, 70c, 70d, 80c, 80d: Joining surface 11: Other members 12a, 21a, 22a, 52, 61, 72a, 81a: Inner pipe 12b, 21b, 22b, 53, 62, 72b, 81b: Outer tube 21c, 21d, 51d, 51c, 63c, 63d, 82c, 82d: Contact portion 11c, 12c, 22c, 52c, 61c, 81c: Projection (inner projection )
11d, 12d, 22d, 53d, 62d, 81d: Projection (outside projection)
12: Multiple pipe member 20, 70: Piston for internal combustion engine 21: Piston upper part 22: Piston lower part 20w, 70w: Cooling channel 50: Exhaust manifold 51: Mounting flange 50g, 60g: Thermal insulation space 60: Water supply pipe 63: Female joint 64 : Male joint 70e: Cavity 70g: Ring groove 70L: Ring member 80: Closed cavity type piston 81: Piston body 82: Piston cap JIG: Jig Sc, Sd: Projection marginal area Sc / Sd: Projection margin Cross-sectional area ratio

Claims (5)

A ring projection welding method of a multi-pipe member having an inner tube and an outer tube containing the inner tube, each of the end surfaces of the inner tube and the outer tube, and another member, the end surface of the inner tube; The sum (Sc) of the proximate sectional area of the projection formed on at least one of the portions corresponding to the end surface of the inner tube on the other member is the end surface of the outer tube and the outer surface on the other member. A ring projection welding method, wherein the ring projection welding method is formed smaller than a sum (Sd) of a proximate sectional area of a projection formed on at least one of the portions corresponding to the end face of the tube. The sum of the marginal sectional areas of the projections formed on at least one of the end surface of the inner tube and the portion corresponding to the end surface of the inner tube on the other member is (Sc), and the end surface of the outer tube (Sc / Sd) is 0.4 when the sum of the cross sectional areas of projections formed on at least one of the parts corresponding to the end face of the outer tube on the other member is (Sd). The ring projection welding method for multi-pipe members according to claim 1, wherein the ring projection welding method is set to ˜0.9. A member of a multi-pipe member having an inner tube and an outer tube enclosing the inner tube, wherein each end surface of the inner tube and the outer tube and another member are welded and joined by ring projection welding. Of the projections formed on at least one of the end surface of the other member and the portion corresponding to the end surface of the inner tube on the other member, the sum of the cross sectional area of the projection formed on the other member, The multiple pipe member formed smaller than the sum of the proximate cross sectional areas of the projections formed on at least one of the portions corresponding to the end surface of the outer tube and the other member are welded and joined by ring projection welding. Ring projection welding member. 4. The ring according to claim 3, wherein the ring projection welding member is an internal combustion engine piston, and the multiple pipe member is one or both of the internal combustion engine piston divided into an upper part and a lower part. Projection welding member. 4. The ring according to claim 3, wherein the ring projection welding member is an exhaust manifold, and the multiple pipe member is a branch pipe obtained by dividing a part of the exhaust manifold into a mounting flange and a branch pipe. Projection welding member.

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