JP2020002911A - Manufacturing method of component and fuel injection valve - Google Patents

Abstract

To suppress the poor welding of metal components.SOLUTION: In a process for manufacturing a fuel injection valve having an adapter 2 having a fuel passage FP at a center and a core 1, an external peripheral face of the core is formed smaller than an internal peripheral face of the adapter so that an airgap g1 communicating with a fuel passage is interposed between circumferential faces of the adapter and the core opposing each other in a radial direction in a fitting part of the adapter and the core, a protrusion p is formed at an end face 2s of the adapter in advance so as to communicate with the fuel passage via the airgap g1 between the circumferential faces of the adapter and the core by pushing and pressing the adapter into the core, and crushing the protrusion by an end face 1s of the core 1, thus making the protrusion flexibly circulate, a caulking part communicating with a space at the outside of the adapter and the core via an airgap g2 between the end faces of the adapter and the core is formed between the circumferential faces, the adapter and the core are temporarily fastened, and the end faces of the adapter and the core are welded to each other so as to melt at least a part of the caulking part.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for manufacturing a component in which a plurality of metal members are joined, and a fuel injection valve including the component.

  A fuel injection valve often includes a part in which a plurality of metal members are connected. As a method of manufacturing this type of fuel injection valve, a core, which is an inner metal member (hereinafter, inner member), is pressed into a metal joint, which is an outer metal member (hereinafter, outer member), and then the core and the metal joint are joined together. Is known (see Patent Document 1 and the like).

  Further, when two metal members constituting the fuel injection valve are laser-welded, the metal members may be temporarily fixed by caulking as a pre-process of laser welding. As one example, there is known an example in which a plunger rod as an inner member is inserted into an anchor as an outer member, and a punch is driven into an end face of the plunger rod in a center hole of the anchor (see Patent Document 2). In the same document, the metal material at the outer edge of the end face of the plunger rod is pushed away by the punch in the center hole of the anchor and plastically flows radially outward, and the plastic material that has flowed plastically is pressed against the inner peripheral surface of the anchor, And the plunger rod are fixed. After the two members are temporarily fixed in this manner, the lower end of the anchor is laser-welded to the plunger rod.

International Publication No. WO 2014/196240

JP 2001-71161 A

  When a press-fitting step is performed prior to laser welding as described in Patent Document 1, lubricating oil is generally required to prevent seizure between metal members during press-fitting. When the press-fitted portion and the welded portion are close to each other, the lubricating oil used at the time of press-fitting may be gasified by welding heat input to cause poor welding such as blow holes. Without lubrication, seizure easily occurs at the time of press-fitting, and the press-fitting itself cannot be completed, or the air confined in minute gaps caused by rubbing of the contact surface between metal members expands due to welding heat input, causing blow holes. May occur.

  On the other hand, in the method described in Patent Document 2, a punch must be driven into the end face of the plunger rod. Therefore, it is premised that there is an end face of the inner member, that is, a target to be punched, in the center hole of the outer member like the anchor and the plunger rod exemplified in the document. Therefore, it cannot be applied to a structure in which two cylindrical members having the same inner diameter, such as a pipe joint, are inserted in a spigot structure. Further, a punch mark (recess) may remain on the end surface of the inner member in the vicinity of the inner peripheral surface of the outer member, and the self-tightening force of the caulked portion between the outer member and the inner member may decrease due to insufficient rigidity.

  In addition, for example, by pressurizing the end face of the inner member with a punch, microscopically, the plastic flow in the outer diameter direction in advance and the part closely contacting the inner peripheral surface of the outer member is pushed down as the punch descends The phenomenon of being strongly rubbed against the inner peripheral surface of the outer member occurs instantaneously. As described above, the microscopic phenomenon in which the metal material flows in the outer diameter direction and is sheared repeatedly occurs until the bottom dead center of the punch. Since the metal member of the fuel injection valve is generally manufactured by machining, the inner peripheral surface of the outer member has a helical tool mark during turning, and the inner peripheral surface of the outer member has an axial direction. Has fine irregularities in the waveform. Therefore, when the punch is driven, the metal material of the inner member rubs against the unevenness of the inner peripheral surface of the outer member, and the adhesion of the metal material of the inner member to the inner peripheral surface of the outer member may be reduced.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a component in which a defect such as a blowhole is unlikely to occur in a weld between metal members, and a fuel injection valve including the component.

  In order to achieve the above object, the present invention provides a method for manufacturing a part in which an inner member is inserted into an outer member and welded, wherein a radially opposed portion of the fitting portion between the outer member and the inner member is provided. The outer peripheral surface of the inner member is formed smaller than the inner peripheral surface of the outer member so that a cylindrical gap is interposed between the circumferential surfaces of the outer member and the outer member and the outer member are opposed in the axial direction. A protruding portion is provided on one of the end surfaces, the inner member is inserted into the outer member and pressed, and the protruding portion provided on one end surface of the outer member and the inner member is crushed by the other end surface. Plastic flow to ensure the gap between the outer member and the inner member circumferential surface and to allow the outer member and the inner member A caulking portion communicating with a space outside the outer member and the inner member through a space between the surfaces is formed between the circumferential surfaces to temporarily fix the outer member and the inner member, and at least one of the caulking portions is formed. The end surfaces of the outer member and the inner member are welded to each other so as to melt the portion.

  ADVANTAGE OF THE INVENTION According to this invention, the defect, such as a blowhole of the welding part of metal members, can be suppressed.

Sectional drawing showing the schematic structure of the fuel injection valve (finished product) according to the first embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a cross section of a pressing unit used when plastically coupling (coupling) the outer member and the inner member according to the first embodiment of the present invention. FIG. 2 is an enlarged sectional view of a fitting portion (before pressing) of the outer member and the inner member according to the first embodiment of the present invention (an enlarged view of a portion C in FIG. 2). FIG. 2 is an enlarged sectional view of a fitting portion (during pressing) of the outer member and the inner member according to the first embodiment of the present invention (an enlarged view of a portion C in FIG. 2). FIG. 2 is an enlarged sectional view of a fitting portion (after pressing) of the outer member and the inner member according to the first embodiment of the present invention (an enlarged view of a portion C in FIG. 2). Sectional drawing showing the state which fitted the outer member and the inner member which concern on 1st Embodiment of this invention. Sectional drawing showing the state which welded the outer member and the inner member which fitted in 1st Embodiment of this invention. Sectional drawing which expanded an example of the welding part of an outer member and an inner member shown in FIG. Sectional drawing which expanded another example of the welding part of an outer member and an inner member shown in FIG. An enlarged sectional view of a fitting portion (before pressing) of an outer member and an inner member according to a second embodiment of the present invention. An enlarged sectional view of a fitting portion (after pressing) of an outer member and an inner member according to a second embodiment of the present invention. Diagram showing a first modified example Diagram showing a second modified example The figure showing the 3rd modification.

  Embodiments of the present invention will be described below with reference to the drawings.

(1st Embodiment)
-Schematic configuration of fuel injection valve-
FIG. 1 is a sectional view showing a schematic configuration of a fuel injection valve (completed product) according to a first embodiment of the present invention. The fuel injection valve 30 shown in the figure is of an electromagnetic drive type, and includes a magnetic circuit unit (described later), a valve unit (described later), an adapter 2 and the like.

  The magnetic circuit section includes a core (solenoid core) 1, a housing 3, a nozzle holder 4, a mover 9, a coil 6, a terminal 7, and the like. The nozzle holder 4 is a cylindrical component, and is mounted on the distal end side (the lower side in the figure) of the cylindrical core 1. A coil 6 is provided on the outer periphery of the core 1. The periphery of the core 1 and the coil 6 is further surrounded by the housing 3. The adapter 2 is a pipe joint for connecting the fuel injection valve 30 to a fuel supply pipe (not shown), and is welded to the base end side of the core 1 (upper side in the figure). The adapter 2, the core 1, and the nozzle holder 4 are each provided with a center hole, and these center holes are connected to form a fuel passage FP. Fuel from a high-pressure fuel pump (not shown) is supplied to the fuel passage FP via a fuel supply pipe.

  The valve section includes a plunger rod 5, an orifice cup 8, and the like. The orifice cup 8 is a fuel injection unit having a plurality of fuel injection holes, and is mounted on the tip of the nozzle holder 4. The plunger rod 5 is a valve body of the fuel injection valve 30, and is accommodated in the fuel passage FP so as to be slidable in the axial direction. The mover 9 is mounted on the base side (core 1 side) of the plunger rod 5. A spring S is accommodated in the fuel passage FP of the core 1, and the tip of the plunger rod 5 is pressed against the orifice cup 8 by the spring S. When the orifice cup 8 is pressed, the fuel injection hole of the orifice cup 8 is closed.

  With such a configuration, when a current supplied through the terminal 7 (drive circuit) flows through the coil 6, the core 1 is excited to generate a magnetic attractive force, and the movable element is opposed to the restoring force of the spring S. 9 is aspirated. With the movement of the mover 9, the plunger rod 5 is separated from the orifice cup 8, the fuel injection hole of the orifice cup 8 opens, and the fuel in the fuel passage FP pressurized by the high-pressure fuel pump is ejected from the fuel injection hole.

-Outer member / Inner member-
The “outer member” and the “inner member” referred to in the specification of the present application are parts of a fuel injection valve, and the inner member is inserted into the outer member, and then joined to each other by welding (eg, laser welding). Further, a condition is that at least one of the outer member and the inner member has a center hole. In the present embodiment, an example in which the adapter 2 is an outer member and the core 1 is an inner member will be described. In this example, both the core 1 and the adapter 2 have a cylindrical structure having a center hole, and the center holes (that is, the fuel passages FP) have the same diameter (FIGS. 6 and 8). It is not limited to exactly the same, and a manufacturing error is allowed. The core 1 and the adapter 2 have substantially the same outer diameters (outer diameters of the core 1 and the adapter 2) of end faces 1s and 2s described later.

  FIG. 2 is a schematic diagram showing a cross section of a pressing unit used when plastically coupling (coupling) the outer member and the inner member. 3 to 5 are enlarged cross-sectional views of a fitting portion (C portion in FIG. 2) between the outer member and the inner member. FIG. 3 shows a state before pressing, FIG. 4 shows a state during pressing, and FIG. 5 shows a state after pressing. ing. 6 is a cross-sectional view showing a state where the outer member and the inner member are fitted (before welding), FIG. 7 is a sectional view showing a state where the fitted outer member and the inner member are welded, and FIGS. 8 and 9 are FIGS. FIG. 5 is an enlarged sectional view of a welded portion between the outer member and the inner member shown in FIG.

  The fitting portion between the core 1 and the adapter 2 has an insertion structure. The adapter 2 as the outer member has a circular concave portion 2p, and the core 1 as the inner member has a cylindrical convex portion 1p. I have. The protrusion 1p is inserted into the recess 2p. Specifically, the fitting portion of the core 1 and the adapter 2 includes two end surface facing portions having different axial positions, and a circumferential surface facing portion connecting the two end surface facing portions.

  The first end surface facing portion is a facing portion between the end surface 2s of the adapter 2 and the end surface 1s of the core 1. The end surfaces 1 s and 2 s are surfaces facing in the axial direction and are annular end surfaces having outer peripheral surfaces of the core 1 and the adapter 2 as outer edges. The end surface 2 s of the adapter 2 which is an outer member is located at the most distal end side of the adapter 2 ( This is a portion located on the downstream side in the fuel flow direction (upper side in FIG. 2). The end surfaces 1s and 2s have approximately the same area.

  The second end face opposing portion is an opposing portion between the end face 2t (FIG. 8) of the adapter 2 and the end face 1t (same) of the core 1, and is located upstream of the first end face opposing portion in the fuel flow direction (FIG. 2). Lower). The end surfaces 1t and 2t are surfaces facing in the axial direction, are annular end surfaces having inner peripheral surfaces of the core 1 and the adapter 2 (inner walls of the fuel passage FP) as inner edges, and the end surface 1t of the core 1 as an inner member is The core 1 is located at the most proximal end side (upstream in the fuel flow direction, lower side in FIG. 2). The end surfaces 1t and 2t have approximately the same area.

  The circumferential surface facing portion connecting these two end surface facing portions is a facing portion between the inner circumferential surface of the concave portion 2p of the adapter 2 and the outer circumferential surface of the convex portion 1p of the core 1. The inner peripheral surface of the concave portion 2p extends in the axial direction and connects the end surfaces 2s and 2t, and the outer peripheral surface of the convex portion 1p also extends in the axial direction and connects the end surfaces 1s and 1t. The axial lengths (the distance between the end surfaces 1s and 1t and the distance between the end surfaces 2s and 2t) of the inner peripheral surface of the concave portion 2p and the outer peripheral surface of the convex portion 1p are substantially the same.

  In the fitting portion of the core 1 and the adapter 2, the concave portion 2 p is formed so that a cylindrical gap g1 communicating with the center hole (fuel passage FP) is interposed between the radially opposed circumferential surfaces. The outer peripheral surface of the protrusion 1p is formed smaller than the inner peripheral surface. Further, a protruding portion p is provided so as to protrude in the axial direction on one of the end surfaces 1 s and 2 s of the core 1 and the adapter 2 which face each other in the axial direction (the end surface 2 s on the adapter 2 side in this embodiment). The protruding portion p is a portion formed in advance to form a caulking portion p ′ (FIG. 5) described later. In the present embodiment, the protruding portion p is provided only on the end surface 2s of the end surfaces 1s and 2s, and the number of installation is one. Only. The protruding portion p is not provided at a portion other than the end surface 1 s in the fitting portion of the core 1 and the adapter 2. The protruding part p is a part of the adapter 2 that comes into contact with the core 1 first when fitted in the axial direction. The protruding portion p may be provided on the second end face opposing portion located on the inner peripheral surface side of the core 1 and the adapter 2, but as in the present embodiment, the first protruding portion p located on the outer peripheral surface side of the core 1 and the adapter 2 is provided. Is desirably provided at the end face facing portion.

  The protruding portion p is provided on the entire periphery of the ring-shaped end surface 2s of the cylindrical concave portion 2p and is formed in a ring shape. The protruding portion p is provided along the inner peripheral surface on the end surface 2s (at the inner peripheral side edge) so as to be located near the opposing portion of the inner peripheral surface of the concave portion 2p and the outer peripheral surface of the convex portion 1p. . When viewed in a cross section cut along a plane including the central axis of the core 1 and the adapter 2 as shown in FIG. 3, the cross section of the protruding portion p is from the base side (in this example, the end face 2s side) to the tip side (in this example, the end face (1s side). With such a shape, the rigidity (deformation resistance) of the protruding portion p is lower than that of the end surfaces 1s and 2s even if the core 1 and the adapter 2 have the same metal material. Therefore, when the core 1 is inserted into the adapter 2 and pressed, the protruding portion p is crushed by the facing end surface 1s and plastically flows in the radial direction (FIG. 4). As a result, the protrusion p (including the metal material of the adapter 2 around the protrusion p displaced by the flow of the protrusion p) includes a ring-shaped caulked portion p pressed against the outer peripheral surface of the protrusion 1p of the core 1. Form '. Thus, the core 1 is temporarily fixed to the adapter 2 by the caulked portion p 'formed between the circumferential surfaces of the core 1 and the adapter 2 (FIG. 5). The installation position and volume of the protruding portion p are considered in advance so that a desired axial dimension L1 of the caulked portion p 'can be secured. The axial dimension L1 is longer than the radial dimension L2 of the gap g1 between the core 1 and the circumferential surface of the adapter 2 (L1> L2). Also take into account. As described above, since the gap g1 is secured between the circumferential surfaces of the concave portion 2p facing the convex portion 1p, the caulked portion p 'is formed with the center hole through the gap g1 (strictly, the gap g1 and a gap g3 described later). (Fuel passage FP) (FIG. 8). Further, even after pressing, a caulked portion p 'remains between the end surfaces 1s, 2s, so that a gap g2 exists between the end surfaces 1s, 2s, and a gap g3 intervenes between the end surfaces 1t, 2t. The caulked portion p 'also communicates with the space outside the core 1 and the adapter 2 via the gap g2. That is, in the temporarily fixed state before the welding after the pressing, the caulked portion p ′ communicates with both the outer circumferential space and the inner circumferential space (fuel passage FP) of the core 1 and the adapter 2 via the gaps g1 to g3. (FIGS. 5 and 8).

  In the present embodiment, the case where the protruding portion p has a triangular shape (including a shape in which a vertex portion is chamfered) is illustrated. In this case, it is preferable that the vertex of the cross section (the portion facing the end face 1s) is offset toward the inner diameter side, but the shape is not particularly limited. Further, the cross-sectional shape of the protruding portion p is not limited to a triangular shape, and may be, for example, a quadrangle or more polygonal shape, a semicircular shape as described later in the second embodiment (FIG. 10), or an appropriately different shape. Can be. The term “semicircular” means not only a strict semicircle but also a shape drawn by a curve having no inflection point including an ellipse. The polygon is a shape including a quadrangle (including a square, a rectangle, a trapezoid, and the like), a pentagon, a hexagon,..., And is not necessarily limited to a regular polygon, and the top is not limited to a square but may be a round.

-Manufacturing method of fuel injection valve-
The manufacturing method of the fuel injection valve in the present embodiment can be the same as a general manufacturing process except for a joining process of the core 1 as the inner member and the adapter 2 as the outer member. Therefore, the joining process of the core 1 and the adapter 2 will be described here.

  First, as shown in FIG. 2, the pressing unit presses the core 1 to press the protruding portion p of the adapter 2 with the end surface 1 s of the core 1 to cause plastic deformation. The pressing unit shown in FIG. 1 includes a punch 10 that presses the core 1 from above, a guide 11 that covers the pressing core 1 and the adapter 2, a jig 12 that is constrained by the guide 11 and receives the core 1 and the adapter 2, and the like. ing. The contact portion of the punch 10 with the core 1 is a flat surface, and the punch 10 makes surface contact with the entire end face (the upper end face in the figure) of the core 1 on the most downstream side in the fuel flow direction. The punch 10 is formed of, for example, SKD 11 of die steel or the like, and is quenched and tempered so as not to be plastically deformed when the core 1 is pressed, so that the hardness and toughness are increased. Metal has an elastic deformation region and a plastic deformation region, and when pressure is stopped in the elastic deformation region, the metal returns to its original shape. In this example, since the protrusion p needs to be plastically deformed, the core 1 is pressed by the force of the plastic deformation region. When the core 1 and the adapter 2 are made of a general SUS430 material, for example, a stainless material, the use of the punch 10 allows the protrusion 10 to be plastically deformed without the punch 10 being deformed. it can. Although not particularly shown, the use of a jig for restraining the outer periphery of the core 1 and the adapter 2 can suppress the axial deviation between the core 1 and the adapter 2 at the time of pressing. In addition, by using a stopper that limits the amount of pushing of the core 1 during pressing, variation in the axial length of the coupling component including the core 1 and the adapter 2 can be suppressed.

  When the core 1 and the adapter 2 are set in the pressing unit described above, and the core 1 is pressed toward the adapter 2 by the punch 10, the end surface 1s of the core 1 comes into contact with the protrusion p as shown in FIG. I do. When the core 1 is further pushed down, the protruding portion p is crushed by the end surface 1s and plastically flows in the radial direction. Since the protruding portion p is close to the circumferential surfaces of the core 1 and the adapter 2 which face in the radial direction, the caulking portion p ′ (see FIG. 5) is formed, and a self-tension force acting as a residual stress acts between the opposing circumferential surfaces of the core 1 and the adapter 2. Thereby, the core 1 and the adapter 2 can be temporarily fixed.

  At this time, the end surface of the adapter 2 and the end surface 1s of the core 1 (excluding the contact portion between the crimped portion p 'and the end surface 1s) are completely formed by the springback (internal residual stress) of the protruding portion p (crimped portion p'). There is no contact. Therefore, a gap g1 and a gap g3 are formed between the end faces 1s and 2s of the core 1 and the adapter 2 and between the end faces 1t and 2t.

  When the temporary fixing of the core 1 and the adapter 2 is completed, the temporarily fixed core 1 and the adapter 2 are taken out from the pressing unit, and the end surfaces 1s and 2s are welded from the outer peripheral side to the entire periphery. At this time, at least a part of the swaged portion p 'is melted to form the welded portion 20 (FIGS. 7 to 9). After that, each part is attached to the joined core 1 and adapter 2 to complete the fuel injection valve 30. The finished product is inspected as appropriate and then incorporated into a target product such as an engine.

-Configuration of characteristic parts of fuel injection valve-
A feature of the fuel injection valve 30 as a finished product is the structure of the joint between the core 1 and the adapter 2. In this example, first, a center hole having the same diameter is provided in both the core 1 and the adapter 2, and the core 1 and the adapter 2 are joined to connect the center holes of each other. A shaped fuel passage FP is formed. The outer diameters of the core 1 and the adapter 2 at the weld 20 are also equal. Further, a welded portion 20 in which the axially opposed end surfaces 1s and 2s of the core 1 and the adapter 2 are joined to each other forms a gap g1 between the circumferential surfaces of the core 1 (the convex portion 1p) and the adapter 2 (the concave portion 2p). And a center hole (fuel passage FP) through a gap g3 between the end surfaces 1t and 2t. The axial dimension L1 of the caulked portion p 'is desirably larger than the radial dimension L2 of the gap g1 as described above, but the entire caulked portion p' overlaps the welded portion 20 as shown in FIG. In this case, the swaged portion p 'does not remain after welding. If the axial dimension L1 of the caulked portion p ′ is adjusted to be longer than the axial dimension of the welded portion 20 by adjusting the volume or the like of the protruding portion p, the caulked portion p ′ can reduce the welded portion 20 as shown in FIG. It can be configured to be formed beyond and remain after welding.

-Effect-
(1) In the present embodiment, there is an inner / outer diameter difference (gap g1) in the insertion portion of the core 1 with respect to the adapter 2, and the component tolerance of the insertion portion of the core 1 with respect to the adapter 2 can be set wide. As a result, processing costs and dimensional control costs can be simplified, and costs can be reduced. Also, unlike the conventional press-fitting structure, at the stage when the core 1 is inserted into the adapter 2, no binding force is generated between them. When joining the core 1 and the adapter 2 which are free from each other, the core 1 and the adapter 2 are temporarily fixed by caulking before welding as described above. This caulking method is different from a general method in which a punch is cut into an object to plastically flow a metal material. This is performed by utilizing the difference in rigidity. The punch 10 is used only to press the core 1 and does not make a punch mark on the core 1. The punch 1 is crushed by pressing the core 1 against the adapter 2, and caulking is performed by the plastic flow. . By joining the core 1 and the adapter 2 by such caulking, a joining force equivalent to that of the press-fitting structure can be obtained. In addition, since lubricating oil required for press-fitting is not required, a step of applying lubricating oil to the press-fitted portion of the core 1 and the adapter 2 and a step of removing (cleaning) oil after press-fitting can be omitted. Also, unlike the caulking process of forming a punch mark, the core 1 and the adapter 2 to be joined are pressed against each other, so that the caulked portion p 'is deformed to form It does not slip on the outer peripheral surface. Microscopically, a phenomenon in which the portion that first came into close contact with the outer peripheral portion of the core 1 stays in place, and the adjacent portion of the adapter 2 subsequently comes into close contact with the outer peripheral portion of the core 1, As a result, the caulked portion p ′ gradually expands in the axial direction (downward in FIG. 5) inside the gap g1. Since the metal material of the adapter 2 enters the inside of the minute groove of the tool mark on the outer peripheral surface of the core 1 into the inner diameter direction, the minute groove formed by the tool mark fills the joint surface between the caulked portion p ′ of the adapter 2 and the core 1. It can be a contact surface. There is no need to make a punch mark, and there is also an advantage in that the two cores 1 and the adapter 2 having the same inner and outer diameters can be joined by caulking. Is applicable).

  By temporarily fixing the core 1 and the adapter 2 in advance as described above, the two can be accurately joined by welding. At that time, at the stage after the temporary fixing and before the welding, a crushed protruding portion p (a part of the caulked portion p ′) remains between the core 1 and the end surfaces 1s, 2s of the adapter 2, and between the end surfaces 1s, 2s and the end surface 1t. , 2t have gaps g2, g3. A gap g1 is secured between the radially opposed circumferential surfaces of the core 1 and the adapter 2 at the stage of manufacturing the core 1 and the adapter 2. Therefore, the caulked portion p 'communicates with the space (fuel passage FP) on the inner diameter side of the core 1 and the adapter 2 via the gaps g1 and g3, and communicates with the space on the outer diameter side of the core 1 and the adapter 2 via the gap g2. . Therefore, in the process of welding the end surfaces 1 s and 2 s of the core 1 and the adapter 2 along the outer peripheral surface, the gas expanded by the welding heat around the welded portion 20 due to the gaps g <b> 1-g <b> 3 serving as an escape path is pressurized. And blow-out is suppressed, and the occurrence of blow holes is suppressed. In addition, since the metal material of the adapter 2 penetrates into the minute groove of the tool mark on the outer peripheral surface of the core 1 at the caulked portion p ′ as described above, air is trapped between the caulked portion p ′ and the surface of the core 1. Generation (enclosement of air) can be suppressed. This can also suppress blow holes due to expansion of the enclosed air. Further, since lubricating oil for temporarily fixing the core 1 and the adapter 2 is not required, the occurrence of blow holes due to oil during welding can be suppressed. In this way, the occurrence of blow holes can be effectively suppressed, and poor welding of the core 1 and the adapter 2 can be reduced, so that the two can be more firmly connected with good sealing properties. Further, when a punch mark (recess) is formed on the core 1 or the adapter 2, the punch mark is close to the swaged portion, which may cause a reduction in the strength of the structural material. Reduction can also be suppressed.

  (2) In addition, by setting the axial dimension L1 of the caulked portion p 'to be larger than the radial dimension L2 of the gap g1, the coupling area between the core 1 and the adapter 2 at the caulked portion p' is increased. High bonding strength can be ensured. However, if the core 1 and the adapter 2 can play a role of temporary fixing even when L1 ≦ L2, it is not always necessary to adopt a configuration in which L1> L2 after caulking.

  (3) If the size and shape of the cross section of the welded portion 20 are the same between the example of FIG. 8 and the example of FIG. 9, the swaged portion p ′ remains beyond the welded portion 20 as shown in FIG. By doing so, the contact area between the core 1 and the adapter 2 at the swaged portion p 'can be increased as compared with the example of FIG. Accordingly, the example of FIG. 9 can improve the bonding strength as compared with the example of FIG.

(2nd Embodiment)
FIGS. 10 and 11 are enlarged cross-sectional views of a fitting portion between an outer member and an inner member according to a second embodiment of the present invention, corresponding to FIGS. 3 and 5, respectively. The present embodiment is different from the first embodiment in the shape of the protruding portion p, and the other configuration and the caulking method are the same as those in the first embodiment. As shown in FIG. 10, in the present embodiment, the cross-sectional shape of the protruding portion p of the adapter 2 is not triangular but semi-circular. Even with such a configuration, by pressing the core 1 against the adapter 2, it is possible to finally achieve the same connection state (FIG. 5) as in the first embodiment as shown in FIG. The same effects as in the first embodiment can be obtained.

(Modification)
Note that the technical scope defined by the present invention is not limited to the modes exemplified in the above embodiments, and can be appropriately changed without departing from the essential technical idea. For example, as shown in FIG. 12, the core 1 may be formed as an outer member, the adapter 2 may be formed as an inner member, and the adapter 2 may be inserted into the core 1. In the example of FIG. 12, only one ring-shaped protrusion p is provided only on the end surface 1s of the core 1. Further, as shown in FIG. 13, a configuration may be adopted in which a protruding portion p is provided at a portion (the end surface 1 t or the end surface 2 t) facing the inner surface of the core 1 and the adapter 2. Also in this configuration, a deformation portion of the protruding portion p can form a caulked portion communicating with the space on the inner and outer diameter sides of the core 1 and the adapter 2 via the gaps g1 to g3. In this case, as in the above-described respective examples, the welded portion 20 is formed by melting at least a part of the caulked portion formed by the deformation of the protruding portion p, as indicated by the two-dot chain line in FIG. Also, as shown in FIG. 14, the present invention can be applied to a case where only one of the two components 100 and 200 has a center hole and the other component 100 is solid. Even in such a case, since the protruding portion p and thus the caulking portion p 'communicate with the center hole of the component 200, the same effects as those of the above-described examples can be obtained. Furthermore, although the case where the present invention is applied to the joining of the core 1 and the adapter 2 has been described as an example, other combinations of components (for example, the mover 9 and the plunger rod 5, or the nozzle holder 4 and the housing 3) are also required. The present invention can be applied according to.

  Further, in the above embodiment, the case where the present invention is applied to the parts of the fuel injection valve is described as an example. However, the outer member and the inner member are not limited to the parts of the fuel injection valve, and two metal parts (both metal parts) are used. The present invention can be applied to various members having a fitting structure (including a case where there is no center hole) and a manufacturing method thereof.

DESCRIPTION OF SYMBOLS 1 ... Core (solenoid core, inner member), 1s, 1t ... End surface, 2 ... Adapter (outer member), 2s, 2t ... End surface, 20 ... Fused part, 30 ... Fuel injection valve, FP ... Fuel passage (center hole) G1-g3: gap; L1: axial dimension of the swaged portion; L2: radial dimension of the gap between the circumferential surfaces of the outer member and the inner member; p: protruding portion; p ': swaged portion

Claims (9)

A method for manufacturing a part in which an inner member is inserted into an outer member and welded,
In the fitting portion of the outer member and the inner member, the outer peripheral surface of the inner member is larger than the inner peripheral surface of the outer member so that a cylindrical gap is interposed between the circumferential surfaces of the outer member and the inner member. Is formed small, and a projection is provided on one of the axially opposed end surfaces of the outer member and the inner member,
The outer member and the inner member are inserted by inserting and pressing the inner member into the outer member and crushing the protruding portion provided on one end surface of the outer member and the inner member by the other end surface to cause plastic flow. While securing the space between the circumferential surfaces of the members, a caulking portion communicating with the space outside the outer member and the inner member through the space between the end surfaces of the outer member and the inner member is provided between the circumferential surfaces. Forming and temporarily fixing the outer member and the inner member,
A manufacturing method of welding the end surfaces of the outer member and the inner member so as to melt at least a part of the caulked portion.   The method according to claim 1, wherein the protrusion is formed in a triangular cross section, a semicircular cross section, or a quadrangular cross section. A fuel injection valve including a part obtained by inserting and welding an inner member to an outer member, wherein at least one of the outer member and the inner member has a center hole,
In the fitting portion of the outer member and the inner member, the outer peripheral surface of the inner member is formed smaller than the inner peripheral surface of the outer member, and the center hole is formed between the circumferential surfaces of the outer member and the radially opposed surfaces. There is a cylindrical void that leads to
A fuel in which a welded portion in which axially opposed end surfaces of the outer member and the inner member are joined to each other through the gap between circumferential surfaces of the outer member and the inner member. Injection valve. One of the outer member and the inner member is a solenoid core, and the other is an adapter that is a pipe joint,
The center hole having the same diameter as a fuel passage is provided in both the solenoid core and the adapter, and the solenoid core and the adapter are joined to connect the center holes of each other, so that there is no step due to both center holes. 4. The fuel injection valve according to claim 3, wherein a cylindrical fuel passage is formed.   5. The fuel injection valve according to claim 4, wherein the outer diameter of the solenoid core and the outer diameter of the adapter at the welding portion are equal.   The fuel injection valve according to claim 3, manufactured by the manufacturing method according to claim 1.   7. The fuel injection valve according to claim 6, wherein an axial dimension of the caulking portion is longer than a radial dimension of the space between the outer member and the inner member.   The fuel injection valve according to claim 7, wherein the welded portion is formed so as to overlap the entire swaging portion.   8. The fuel injection valve according to claim 7, wherein the caulked portion is formed beyond the welded portion and remains.

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