WO2022158025A1

WO2022158025A1 - Two-component joined article and method for producing same

Info

Publication number: WO2022158025A1
Application number: PCT/JP2021/031756
Authority: WO
Inventors: 琢將古山; 賢一郡司; 雅史根本
Original assignee: 日立Astemo株式会社
Priority date: 2021-01-20
Filing date: 2021-08-30
Publication date: 2022-07-28
Also published as: JP7502476B2; JPWO2022158025A1; CN116529475A

Abstract

The present invention provides a two-component joined article having a first component that includes a through-hole, a second component that is inserted into the through-hole in the first component, and an annular weld metal that is formed at a portion where the first and second components face each other and that joins the first and second components, the two-component joined article being such that the amount of overlap between the starting end and the finishing end of a back bead of the weld metal is less than the width of the back bead.

Description

Joined product of two parts and its manufacturing method

The present invention relates to a jointed product and a joining method of two parts, and more particularly to a jointed product in which sealing performance of an annular welded portion between two parts is emphasized and a manufacturing method thereof.

As a technique for inserting one part into the other part and welding these two parts along the outer periphery of the other part, for example, the technique described in Patent Document 1 is known.

WO2018/142930

The welding disclosed in Patent Document 1 is penetration welding that penetrates the plate thickness of two parts, and the welded portion is formed in a ring shape. In such welding, the opposing surfaces of the two parts are welded over one turn, and an overlapping portion may be formed in which the weld metal of the first week overlaps the weld metal of the second week. However, there is a tendency that internal cracks and blowholes are likely to occur in this overlapping portion.

An object of the present invention is to provide a joint of two parts and a manufacturing method thereof that can suppress the occurrence of internal cracks and blowholes in the weld metal that joins the two parts.

In order to achieve the above object, the present invention provides a first component having a through hole, a second component inserted into the through hole of the first component, and a and an annular weld metal that joins the first part and the second part, and the amount of overlap between the start end and the end of the back bead of the weld metal is the above To provide a joint of two parts smaller than the width of a back bead.

According to the present invention, it is possible to suppress the occurrence of internal cracks and blowholes in the weld metal that joins two parts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a fuel supply system including a high-pressure fuel supply pump, which is an application example of a two-part joint and a manufacturing method thereof according to an embodiment of the present invention. Sectional view of the high-pressure fuel supply pump shown in FIG. Cross-sectional view taken along line III-III in Fig. 2 Cross-sectional view taken along line IV-IV in Fig. 3 Cross-sectional view taken along line VV in FIG. Enlarged view of part VI in Fig. 4 Enlarged view showing the state before welding of the part shown in FIG. Conceptual diagram explaining the keyhole generation mechanism due to the vapor pressure of metal vapor during welding Explanatory diagram of the occurrence mechanism of solidification cracks in weld metal Explanatory diagram of the occurrence mechanism of solidification cracks in weld metal Explanatory diagram of the occurrence mechanism of solidification cracks in weld metal Explanatory diagram of the occurrence mechanism of solidification cracks in weld metal Explanatory diagram of the occurrence mechanism of solidification cracks in weld metal Explanatory drawing of a method of joining two parts according to one embodiment of the present invention. Explanatory diagram of phenomena occurring at each stage of the joining method of FIG. Explanatory diagram of phenomena occurring at each stage of the joining method of FIG. Explanatory diagram of phenomena occurring at each stage of the joining method of FIG. Explanatory diagram of phenomena occurring at each stage of the joining method of FIG. Schematic diagram of a back bead of a joint of two parts manufactured by a manufacturing method according to an embodiment of the present invention. Enlarged view of XIIB part in FIG. 12A

Embodiments of the present invention will be described below with reference to the drawings.
In some cases, the vertical direction is designated for explanation, but this vertical direction does not mean the vertical direction in the mounting state of the high-pressure fuel supply pump.

－Fuel supply system－
FIG. 1 is a schematic diagram of a fuel supply system including a high-pressure fuel supply pump, which is an application example of a two-part joint and a manufacturing method thereof according to an embodiment of the present invention. Hereinafter, the high-pressure fuel supply pump will be abbreviated as a high-pressure pump. The high-pressure pump illustrated in this embodiment is applied to an engine system that directly injects fuel into the cylinders of an engine.

The dashed frame shown in the figure indicates the pump body 1, which is the body of the high-pressure pump, and the mechanisms and parts shown within this frame are integrally incorporated into the pump body 1. A feed pump 21 is driven based on a signal from an engine control unit 27 (hereinafter referred to as ECU), and the feed pump 21 draws up fuel from a fuel tank 20 . This fuel is pressurized and sent to the fuel suction port 10a of the high-pressure pump through the suction pipe 28 at a predetermined feed pressure. The fuel that has passed through the fuel intake port 10a reaches the intake port 31b of the electromagnetic intake valve unit 300 that constitutes the variable capacity mechanism via the intake joint 51, the pressure pulsation reduction mechanism 9, and the intake passage 10d.

The fuel that has flowed into the electromagnetic intake valve unit 300 flows into the pressurization chamber 11 via the intake valve 30 . Plunger 2 is powered to reciprocate by cam 93 (FIG. 2) of the engine. When the plunger 2 reciprocates, fuel is sucked into the pressurization chamber 11 from the intake valve 30 during the downward stroke of the plunger 2, and is pressurized during the upward stroke. The fuel pressurized in the pressurization chamber 11 is discharged from the high-pressure pump via the discharge valve 8 and the fuel discharge port 12 and is pressure-fed to the common rail 23 . A pressure sensor 26 and a plurality of injectors 24 are attached to the common rail 23 . The number of injectors 24 corresponding to the number of cylinders of the internal combustion engine is attached to the common rail 23. The injectors 24 are opened and closed according to a control signal from the ECU 27, and are opened to inject fuel into the cylinders (combustion chambers) of the engine. The fuel discharge flow rate of the high-pressure pump is adjusted by controlling the electromagnetic intake valve unit 300 by the ECU 27 .

The ball valve 202 opens when the pressure of the common rail 23 rises excessively due to a failure of the injector 24 or the like, and the differential pressure between the pressure of the fuel discharge port 12 and the pressure chamber 11 becomes equal to or higher than the valve opening pressure of the relief valve unit 200 . Excessively pressurized fuel passes through the relief valve unit 200 and is returned from the relief passage 200a to the pressurization chamber 11, thereby protecting the common rail 23 and other high-pressure pipes.

－High pressure pump－
2 is a cross-sectional view of the high-pressure fuel supply pump shown in FIG. 1, FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. be.

As shown in FIGS. 3 and 4, the high-pressure pump of the present embodiment is fixed by fixing the mounting flange 1e provided on the pump body 1 to the outer wall surface of the cylinder head 90 of the internal combustion engine with a plurality of bolts (not shown). be done. An O-ring 61 is fitted in the pump body 1 to seal the space between the cylinder head 90 and the pump body 1, thereby preventing leakage of engine oil.

A suction joint 51 is attached to the pump body 1 as shown in FIG. The intake joint 51 is connected to an intake pipe 28 (FIG. 1) that supplies low pressure fuel from the vehicle's fuel tank 20, from which fuel is supplied to the interior of the high pressure pump. Fuel flowing in from the fuel inlet 10a of the suction joint 51 passes through a low-pressure passage formed inside the pump body 1 and flows into damper chambers formed in the damper upper portion 10b and the damper lower portion 10c. A damper chamber is defined by a damper cover 14 attached to the pump body 1 . The pressure pulsation of the fuel flowing into the damper chamber is suppressed by the pressure pulsation reduction mechanism 9 provided in the damper chamber, and the fuel reaches the suction port 31b of the electromagnetic suction valve unit 300 through the suction passage 10d. The pressure pulsation reduction mechanism 9 is a metal diaphragm damper formed by laminating two corrugated disc-shaped metal plates and injecting an inert gas (for example, argon) into the inside. absorbs and reduces the pulsation of Although FIG. 3 illustrates a configuration in which the suction joint 51 is provided on the side surface of the pump body 1, the suction joint 51 may be provided on the upper surface of the damper cover 14 in some cases.

An electromagnetic suction valve unit 300 and a discharge valve 8 are assembled to the pump body 1 . Fuel is supplied to the pressurizing chamber 11 through the pressurizing chamber inlet passage 1 a formed in the pump body 1 by the electromagnetic suction valve unit 300 . The discharge valve 8 prevents the fuel discharged from the pressure chamber 11 into the discharge passage 12b (FIG. 3) from flowing back. The fuel that has passed through the discharge valve 8 is supplied to the engine through the fuel discharge port 12 of the discharge joint 12c.

A cylinder 6 that guides the reciprocating motion of the plunger 2 is attached to the pump body 1 . The cylinder 6 is press-fitted into the pump body 1 and fixed by caulking. By press-fitting the cylinder 6 , the pressurized fuel is sealed so as not to leak from the pressure chamber 11 through the space between the cylinder 6 and the pump body 1 . Further, the cylinder 6 is in contact with the pump body 1 not only on the outer peripheral surface but also on the upper end surface, and the metal contact between the upper end surface of the cylinder 6 and the pump body 1 also contributes to the sealing of the pressurized fuel.

A tappet 92 is provided at the lower end of the plunger 2 , and the rotary motion of a cam 93 attached to the camshaft of the internal combustion engine is converted into vertical motion by the tappet 92 and transmitted to the plunger 2 . A retainer 15 is attached to the plunger 2 , and the retainer 15 is pushed by the spring 4 to press the plunger 2 against the tappet 92 . As a result, the plunger 2 reciprocates up and down as the cam 93 rotates.

A plunger seal 13 is held at the lower end of the inner circumference of the seal holder 7, and the plunger seal 13 is installed below the cylinder 6 in the drawing. Since the plunger seal 13 slidably contacts the outer periphery of the plunger 2, the fuel in the auxiliary chamber 7a is sealed when the plunger 2 slides, thereby preventing the fuel from flowing into the internal combustion engine. At the same time, the plunger seal 13 also prevents lubricating oil (including engine oil) for lubricating sliding parts in the internal combustion engine from flowing into the pump body 1 .

The discharge valve 8 provided at the outlet of the pressurizing chamber 11 is composed of a seat 8a, a valve body 8b, a spring 8c, a discharge valve plug 8d, and a discharge valve stopper 8e. The valve body 8b is biased toward the seat 8a by a spring 8c, and the discharge valve 8 is opened and closed by contacting or separating the valve body 8b from the seat 8a. The stroke (movement distance) of the valve body 8b is defined by the discharge valve stopper 8e. The discharge valve plug 8 d is the body of the discharge valve 8 and is joined to the pump body 1 with a weld metal 407 . The weld metal 407 separates and isolates the inner space of the pump body 1 through which fuel flows from the outer space of the pump body 1 .

When there is no fuel pressure difference between the pressure chamber 11 and the discharge valve chamber 12a, the valve body 8b is pressed against the seat 8a by the spring 8c, and the discharge valve 8 is closed. When the fuel pressure in the pressure chamber 11 exceeds the fuel pressure in the discharge valve chamber 12a by a certain amount or more, the valve element 8b moves against the spring 8c and the discharge valve 8 opens. At this time, the high-pressure fuel in the pressurization chamber 11 is discharged to the common rail 23 (FIG. 1) through the discharge valve chamber 12a, the discharge passage 12b, and the fuel discharge port 12 shown in FIG. Further, the opening and closing movement of the valve body 8b is guided by the outer peripheral surface of the discharge valve stopper 8e and limited to the stroke direction, and the discharge valve 8 also functions as a check valve.

The pressurization chamber 11 is defined by the pump body 1 , the electromagnetic intake valve unit 300 , the plunger 2 , the cylinder 6 , the discharge valve 8 and the relief valve unit 200 . The rotation of the cam 93 causes the plunger 2 to reciprocate, and when the plunger 2 moves in the direction to expand the volume of the pressurizing chamber 11, fuel is drawn into the pressurizing chamber 11, and the fuel pressure inside the pressurizing chamber 11 decreases. . In this stroke, when the fuel pressure inside the pressurizing chamber 11 becomes lower than the pressure in the suction passage 10d, the suction valve 30 opens.

After the suction stroke, when the plunger 2 changes its operating direction to contract the pressurizing chamber 11, it shifts to the compression stroke. Here, when the electromagnetic coil 43 of the electromagnetic suction valve unit 300 is not energized, the suction valve 30 is opened by being biased by the rod biasing spring 40 . When the volume of the pressurization chamber 11 is reduced, the fuel sucked into the pressurization chamber 11 is returned to the intake passage 10d through the opening of the intake valve 30, which is in the open state. It never rises. This stroke is called a return stroke.

Next, the electromagnetic suction valve unit 300 will be explained using FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. 3, showing a state in which the intake valve is open.

The electromagnetic suction valve unit 300 drives the magnetic core (fixed core) 39, the movable core 36, and the rod 35 by energizing the electromagnetic coil 43 to drive the suction valve 30, which sucks fuel and pressurizes it. Send to Room 11. In the non-energized state, the rod biasing spring 40 pushes the suction valve 30 in the valve opening direction. flows, and a magnetic attraction force is generated in the magnetic core 39 . Along with this, the movable core 36 is pulled toward the valve closing direction on the magnetic attraction surface S by the magnetic attraction force of the magnetic core 39 . A rod 35 is arranged between the movable core 36 and the intake valve 30 , and the rod 35 is provided with a flange portion 35 a for locking the movable core 36 . The electromagnetic coil chamber in which the electromagnetic coil 43 is arranged is covered with a lid member 44 , and the magnetic core 39 also serves as a member for holding the lid member 44 . The rod biasing spring 40 is covered with the portion of the magnetic core 39 that holds the lid member 44 .

The rod 35 is locked to the movable core 36 at the flange portion 35a, and moves together with the movable core 36 when the movable core 36 moves toward the magnetic core 39 side. Therefore, when the magnetic attraction force acts on the movable core 36, the rod 35 moves in the valve closing direction. Between the movable core 36 and the intake valve 30, a valve-closing biasing spring 41 that biases the movable core 36 in the valve-closing direction and a rod guide member 37 that guides the rod 35 in the valve-opening/closing direction are arranged. there is The rod guide member 37 constitutes a spring seat 37b of the valve closing biasing spring 41 . Further, a fuel passage 37a is provided in the rod guide member 37, allowing fuel to flow into and out of the space in which the movable core 36 is arranged.

The movable core 36 , the valve closing biasing spring 41 , the rod 35 and the like are contained in an electromagnetic intake valve unit housing 38 fixed to the pump body 1 . Also, the magnetic core 39 , the rod biasing spring 40 , the electromagnetic coil 43 , the rod guide member 37 and the like are supported by the electromagnetic intake valve unit housing 38 . The rod guide member 37 is attached to the electromagnetic suction valve unit housing 38 on the side opposite to the magnetic core 39 and the electromagnetic coil 43 . The rod guide member 37 includes the suction valve 30 , the suction valve biasing spring 33 and the stopper 32 , and constitutes a part of the electromagnetic suction valve unit housing 38 .

The suction valve 30 , the suction valve biasing spring 33 and the stopper 32 are provided on the opposite side of the magnetic core 39 on the rod 35 . The suction valve 30 is provided with a guide portion 30 b projecting toward the pressurizing chamber 11 side, and the guide portion 30 b is guided by a suction valve biasing spring 33 . As the rod 35 moves, the intake valve 30 moves in the valve opening direction (the direction away from the valve seat 31a) by the valve body stroke 30e to be in the open state, and fuel is supplied to the pressure chamber 11 from the intake passage 10d. . The guide portion 30b stops moving by colliding with the stopper 32 . The stopper 32 is press-fitted and fixed inside the housing (rod guide member 37 ) of the electromagnetic suction valve unit 300 . The rod 35 and the intake valve 30 are separate members independent of each other.

The suction valve 30 closes the flow path to the pressurizing chamber 11 by contacting the valve seat 31a of the valve seat member 31 arranged on the suction side, and closes the flow path to the pressurizing chamber 11 by moving away from the valve seat 31a. open the road When the magnetic biasing force overcomes the biasing force of the rod biasing spring 40 and the rod 35 moves away from the intake valve 30, the biasing force of the suction valve biasing spring 33 and the fluid force of the fuel flowing into the intake passage 10d , the intake valve 30 closes. After the valve is closed, the volume of the pressurizing chamber 11 decreases due to the operation of the plunger 2 and the fuel pressure in the pressurizing chamber 11 increases. Then, high pressure fuel is discharged from the high pressure pump and supplied to the common rail 23 . This stroke is called a discharge stroke. The fuel discharged from the high-pressure pump can be controlled by the timing of energizing the electromagnetic coil 43 .

The relief valve unit 200 includes a relief valve cover 201, a ball valve 202, a relief valve retainer 203, a spring 204, and a spring holder 205. The relief valve unit 200 opens the ball valve 202 to return the fuel to the pressurization chamber 11 only when the common rail 23 or its downstream members have some problem and the pressure exceeds the allowable value.

－Weld metal－
A plurality of through holes for assembling parts are formed in the pump body 1, and assembling parts are inserted into these through holes and joined by welding. Examples thereof include the discharge valve 8 and the discharge joint 12c. The body (discharge plug 8d) of the discharge valve 8 and the discharge joint 12c are joined to the pump body 1 via a weld metal 407 formed by laser welding. The weld metal 407 surrounds the outer peripheral portion of the discharge plug 8d and is annularly formed along the facing portion between the pump body 1 and the discharge plug 8d. The weld metal 407 that joins the discharge joint 12c and the pump body 1 similarly surrounds the outer peripheral portion of the discharge joint 12c and is annularly formed along the facing portion between the pump body 1 and the discharge joint 12c. Suppressing the occurrence of defects such as solidification cracks and blowholes inside the weld metal 407 is important from the viewpoint of sufficiently ensuring the reliability of the weld. In particular, the reliability of the welded portion facing the fuel flow path inside the pump body 1 is important from the viewpoint of preventing leakage of fuel from the pump body 1, and the welded portion is required to have sufficient strength.

Fig. 6 is an enlarged view of the VI section of Fig. 4, that is, an enlarged view of the welded portion between the pump body 1 and the discharge plug 8d. 7 is an enlarged view showing the state before welding of the portion shown in FIG. Here, the structure of the welded portion between the pump body 1 and the discharge plug 8d will be described with reference to FIGS. 6 and 7. The welded portion between the pump body 1 and the discharge joint 12c has the same structure.

As shown in FIG. 7, the discharge plug 8d inserted into the through hole 413 for assembling parts formed in the pump body 1 is formed separately from the portion to be welded (the portion where the weld metal 407 is formed after welding). The pressed-in portion 405 is press-fitted and fixed to the pump body 1 . The press-fit portion 405 is located inside the pump body 1 from the portion to be welded in the direction of the center line O of the discharge plug 8d. At this time, the discharge plug 8d before welding is provided with a flange 414, and the discharge plug 8d is press-fitted into the pump body 1 to a position where the flange 414 contacts the press-fitting receiving surface 406 of the outer wall of the pump body 1. Before welding, there is a slight gap GP between the inner peripheral surface of the through-hole 413 of the pump body 1 and the outer peripheral surface of the discharge plug 8d opposed thereto, unlike the press-fit portion 405 . This gap GP has a conical shape that tapers toward the inside of the pump body 1, and the center line O of the discharge plug 8d approaches the center line O of the discharge plug 8d toward the inside of the pump body 1 as viewed in cross section in FIG. is tilted with respect to A gap 400 is formed between the gap GP (the portion facing the pump body 1 and the discharge plug 8 d ) and the press-fitting portion 405 . When welding the pump body 1 and the discharge plug 8d, the position is aligned with the gap GP in the state of FIG. Rotate the LB. The optical axis of the laser LB is inclined with respect to the center line O of the discharge plug 8d in accordance with the inclination of the gap GP in the cross section of FIG.

As a result of this welding, as shown in FIG. 6, the facing portion between the pump body 1 and the discharge plug 8d is melted and solidified, centering on the portion where the gap GP existed, and the pump body 1 and the discharge plug 8d are separated. Joining weld metal 407 is formed. Since the gap 400 exists, the weld metal 407 has a front bead 415, which is the surface on the incident side of the laser LB (exposed to the space outside the pump body 1), and a back bead 416 exposed in the gap 400. formed. In the cross section of FIG. 6, a straight line 407a passing through the widthwise center of the front bead 415 and the widthwise center of the rear bead 416 is inclined with respect to the center line O of the discharge plug 8d corresponding to the gap GP before welding. is doing. The weld metal 407 is formed around the entire circumference of the discharge plug 8d, and the opposing portion between the pump body 1 and the discharge plug 8d is sealed with the weld metal 407, thereby preventing leakage of fuel from the pump body 1.

－Mechanism of Defect Occurrence in Weld Metal－
FIG. 8 is a conceptual diagram for explaining the mechanism of keyhole generation due to the vapor pressure of metal vapor during welding. As shown in the figure, when the laser LB is irradiated onto the metal member, the metal member is heated by the laser LB and melts when it reaches the melting point, and the metal member becomes partially liquid to form a molten pool MP. After that, the metal member in the vicinity of the laser optical axis of the liquefied molten pool MP is further heated by the laser LB to raise the temperature and evaporate into a metal vapor MV. It is understood that the vapor pressure of this metal vapor MV expands the molten pool MP and forms the keyhole KH. Moreover, this keyhole KH is not formed immediately after irradiating the metal member with the laser LB, but is formed through the steps of forming the molten pool MP and generating the metal vapor MV. The laser LB penetrates the plate thickness TP of the metal member at a stage after the generation of the keyhole KH. After the generation of the keyhole KH, the keyhole KH gradually becomes deeper as the energy of the laser LB increases. , the molten pool MP gradually deepens and penetrates the plate thickness TP.

　Figs. 9A to 9E are diagrams for explaining the mechanism of solidification cracking in the weld metal step by step. In these figures, a second metal part B (FIGS. 1 to 7) is inserted into a cylindrical through hole TH of a first metal part A (pump body 1 in the example of FIGS. 1 to 7). 2, for example, a discharge plug 8d) is press-fitted. Then, the laser LB is irradiated to the opposing portions of the first component A and the second component B, the first component A and the second component B are rotated, and the laser LB is emitted to the cylindrical opposing portions of both components. The scanning process is represented in FIGS. 9A-9E.

In the example of FIGS. 9A to 9E, the center line O of the annular opposing portion (in other words, the gap GP) between the first part A and the second part B is used as a reference, and the keyhole KH is the first part A. And the position of the penetration welding start point P1 penetrating through the plate thickness TP (FIG. 8) of the second component B is assumed to be the azimuth angle θ=0°. The penetration welding starting point P1 is the starting point of the back bead 416 . The molten pool MP and the keyhole KH advance along with the laser LB along a circular orbit from the penetration welding start point P1, and the portions through which the laser LB passes solidify sequentially to form the weld metal WM. FIG. 9A shows the situation while the laser LB travels through a position with an azimuth angle of 0°≦θ≦270°. During this time, a sufficient gap GP remains in the traveling direction of the laser LB, and the metal vapor MV generated inside the keyhole KH flows into the gap GP in the traveling direction of the laser. Then, when the laser LB further advances and reaches the region of the azimuth angle θ≧270° as shown in FIG. gap GP gradually disappears. Further, when the laser LB approaches the penetration welding start point P1, part of the metal vapor MV that tried to flow into the gap GP in the traveling direction of the laser LB as shown in FIG. Collision with WM. Then, the metal vapor MV that has collided with the weld metal WM is pushed back in the direction opposite to the traveling direction of the laser LB by the reaction force, and is contained in the molten pool MP as shown in FIG. 9D. When the molten pool MP containing the metal vapor MV is solidified in this manner, blowholes are generated in the weld metal WM as shown in FIG. 9E, which may cause internal cracks IC of the metal vapor MV.

-Manufacturing method of joint-
On the other hand, the weld metal 407 of the high-pressure pump explained with reference to FIGS. 1-7 is formed by a special welding method for suppressing the occurrence of such internal cracks. As a result, a strong joint is manufactured between the pump body 1 corresponding to the first part A and the discharge plug 8d (or discharge joint 12c) corresponding to the second part B in the example of FIGS. 9A to 9E. The method of manufacturing the two-piece joint includes a laser energy increasing step, a penetration welding step, a laser energy switching step, and a laser energy decreasing step.

The laser energy increasing step is a step of moving the laser while increasing the energy from the front edge of the front bead of the weld metal (laser irradiation start position) along the opposing portions of the first component and the second component. During this time, the energy of the laser LB is increased to the set penetration energy at which the back bead is formed. In the laser energy increasing step, the back bead is not formed because the thickness of the first component and the second component is not sufficient for the melting depth.

In the subsequent penetration welding process, from the position where the energy of the laser LB reaches the above penetration energy, that is, the starting end of the back bead, the penetration energy is maintained and the laser LB is applied along the opposing parts of the first component and the second component for one week. It is a process to let In the penetration welding step, the melt depth reaches the plate thickness of the first component and the second component, and penetration welding is performed, so that a back bead is formed.

In the laser energy switching process following the penetration welding process, when the terminal end of the back bead is reached (in other words, when the penetration welding is made once and returned to the beginning of the back bead), the laser LB is set to the non-penetration energy set at which the back bead is not formed. It is the process of switching energy. As a result, the thicknesses of the first component and the second component are not sufficiently melted again, and the back bead is interrupted here.

The laser energy reduction step is a step of moving the laser LB along the opposing portions of the first component and the second component while decreasing the energy from the non-penetrating energy after the laser energy switching step. During this time, as the energy of the laser LB decreases, the depth of fusion also becomes shallower, and the weld metal (weld metal in the second week) becomes thinner. When the laser LB reaches a predetermined end position of the front bead, the irradiation of the laser LB is stopped and the welding is completed.

A specific example of the manufacturing method of the above-mentioned joined product will be explained using the drawings.

FIG. 10 is an explanatory diagram of a method of joining two parts according to one embodiment of the present invention. In an example in which the laser LB is irradiated clockwise along the annular facing portion between the pump body 1 and the discharge plug 8d, represents the energy control of 11A to 11D are explanatory diagrams of phenomena occurring at each stage of the bonding method of FIG. The azimuth angles shown in these figures correspond to the azimuth angles shown in FIGS. 9A-9E. Welding between the pump body 1 and the discharge plug 8d will be described with reference to FIGS. 10 and 11A to 11D, but the welding between the pump body 1 and the discharge joint 12c is the same.

First, in FIG. 10, the energy amount of the laser LB is changed from 0 to Increases up to the above penetration energy. The process of the section of this laser energy increase rotation angle Ru is the laser energy increase process.

After that, while the laser LB advances along the annular opposing portion of the pump body 1 and the discharge plug 8d by the main welding rotation angle Fp (360°), the energy that penetrates the two parts, the pump body 1 and the discharge plug 8d, is applied. Penetration welding is performed with a laser LB. The process of the section of this main welding rotation angle Fp is the penetration welding process. The back bead 416 is formed only in the section of the main welding rotation angle Fp. In this example as well, when the laser LB approaches the penetration welding start point P1, a part of the metal vapor MV that tried to flow into the gap GP in the traveling direction of the laser LB as shown in FIG. of the weld metal WM (similar to FIG. 9C).

After passing the main welding rotation angle Fp, the energy of the laser LB is reduced from the penetration energy while the laser LB travels along the annular opposing portion of the pump body 1 and the discharge plug 8d by the laser energy sharply decreasing rotation angle Fd. Switch to non-penetrating energy. The process of this section of the laser energy sharply decreasing rotation angle Fd is the laser energy switching process. Here, for example, the laser energy rapid reduction rotation angle Fd is set to about 5-10°, and the energy of the laser LB is rapidly reduced by about 15-20% during this 5-10°. As a result, as shown in FIG. 11B, the keyhole KH shrinks, the amount of the metal vapor MV inside the keyhole KH decreases, and the metal vapor MV stays in the keyhole KH due to the decrease in vapor pressure.

After reducing the energy of the laser LB to the non-penetrating energy, the energy of the laser LB is gradually increased while the laser LB travels along the annular facing portion of the pump body 1 and the discharge plug 8d by the laser energy reduction rotation angle Rd. Decrease. The process of the section of this laser energy reduction rotation angle Rd is the laser energy reduction process. As a result, as shown in FIG. 11C, the metal vapor MV inside the keyhole KH is released to the atmosphere from the laser incident side, during which the keyhole KH disappears and the welding ends.

- Bonding -
A two-component bonded product manufactured by the method described in FIGS. An annular weld metal is formed at opposing portions of the part and the second part to join the first part and the second part. Then, through the laser energy switching process, a unique weld trace remains in which the amount of overlap between the starting end and the terminal end of the back bead of the weld metal is smaller than the width of the back bead.

On the other hand, by performing the laser energy reduction step following the laser energy switching step, the amount of overlap between the start and end of the front bead of the weld metal becomes larger than the width of the front bead. Where the penetration weld where the back bead is formed and the end of the front bead in the second week overlap, the azimuth angle range between the start and end of this overlap based on the center of the annular weld metal reaches over 30 degrees. The overlap between the penetration weld and the end of the front bead in the second week has a shallower melt depth toward the end. The first part referred to here corresponds to the pump body 1 in the high-pressure pump described with reference to FIGS. 1 to 7, and the second part is a part assembled to the pump body 1, such as the body of the discharge valve. The discharge valve plug 8d (or discharge joint 12c) corresponds.

The above joints will be explained using drawings.

FIG. 12A is a schematic diagram of a back bead of a two-part joined product manufactured by the manufacturing method (FIG. 10) according to one embodiment of the present invention, and FIG. 12B is an enlarged view of the XIIB portion in FIG. 12A.

As described above, the melt depth reaches the plate thickness only in the section of the main welding rotation angle Fp (Fig. 10) (penetrates the plate thickness) and the penetration welding is performed, so the back bead 416 is formed only in this section. be done. That is, the back bead 416 is formed only 360 degrees. A back bead starting end portion 411 is formed when the laser LB passes through the starting end of the section of the main welding rotation angle Fp, that is, the penetration welding starting point P1 (FIG. 10). Further, the rear bead end portion 412 is formed when the laser beam LB passes through the end of the section of the main welding rotation angle Fp. Since the laser LB has a circular cross-section, the

tip portions

411a and 412a of the back bead starting end portion 411 and the back bead terminating portion 412 are arcuate following the cross-sectional shape of the laser LB. In this embodiment, the back bead starting end portion 411 and the back bead trailing end portion 412 overlap each other only at the semicircular

leading end portions

411a and 412a, and the overlap amount OL1 is the back bead 416 as shown in FIG. 12B. bead width BW1.

On the other hand, the back bead 416 is formed only at the main welding rotation angle Fp, while the front bead 415 is formed at the laser energy increase rotation angle Ru, the main welding rotation angle Fp, the laser energy sharp decrease rotation angle Fd, and the laser energy decrease rotation angle. It is formed continuously in the section of angle Rd. Therefore, with respect to the penetration weld formed in the section of the main welding rotation angle Fp, the end portion of the front bead 415 in the second round is the total section of the laser energy sharp reduction rotation angle Fd and the laser energy reduction rotation angle Rd. overlap. This overlap amount OL2 (FIG. 11D) is wider than the bead width BW2 of the front bead 415 (FIG. 11D). The azimuth angle range φ (FIG. 11D) between the start and end of the overlapping portion between the end portion of the front bead 415 and the penetration weld portion is 30 degrees or more as described above.

-effect-
(1) According to the present embodiment, as described above, after the start of penetration welding, the timing at which the laser LB returns to the penetration welding start point P1 after making one turn around the facing portion between the first member and the second member , the energy of the laser LB is rapidly reduced to non-penetrating energy. As a result, the overlap amount OL1 between the start end and the end of the back bead of the weld metal becomes smaller than the bead width BW1 of the back bead. In the process of forming the weld metal, through the step of rapidly reducing the energy of the laser LB to the non-penetrating energy, the metal vapor MV is rapidly reduced as described above and stops inside the keyhole KH, and the molten pool MP contains the metal vapor MV. The occurrence of the phenomenon of solidification is suppressed. In this way, it is possible to suppress the occurrence of internal cracks and blowholes in the weld metal that joins the two parts, which is expected to improve the reliability of the joint of the two parts and reduce the maintenance and management cost of welding quality in mass production. can. Since internal cracks in the weld metal are effectively suppressed, high-pressure fuel can be effectively sealed with the weld metal.

(2) In the case of the present embodiment, the back bead of the weld metal overlaps only at the ends, whereas the overlap amount OL2 of the front bead of the weld metal is larger than the bead width BW2 of the front bead 415 . In particular, in this embodiment, the overlapping portion between the penetration weld portion of the weld metal and the end portion of the front bead secures a wide range of 30 degrees or more in the azimuth angle range, so that the two parts can be firmly joined. It is possible to secure sufficient reliability in terms of strength of the joint of the two parts. At that time, by completing the welding through the laser energy reduction process so that the melting depth of the overlapping part between the penetration weld part and the end part of the front bead becomes shallower toward the end, blowholes are generated even in the overlap part. can be more effectively suppressed.

(3) As in the above-described embodiment, the above-described method is preferably applied to the joint between the pump body 1 of the high-pressure fuel pump and the parts (for example, the discharge plug 8d) attached thereto, particularly to the portion facing the high-pressure fuel. can be done. Specifically, since the inside of the pump body 1 of the high-pressure pump is under high pressure, the sealing performance of the assembly parts such as the discharge plug 8d is important from the viewpoint of suppressing fuel leakage, etc., which will be explained with reference to FIGS. 6 and 7. In some cases, a structure that is firmly fixed by interference fitting and welding as described above is adopted. However, it is not easy in terms of accuracy to manufacture the parts so that the facing surfaces of the pump body 1 and the mounting part just contact each other at both the interference fit portion and the welded portion. Therefore, as described with reference to FIG. 7, the portion to be welded may have a clearance fit structure. However, in this case, it is necessary to use a high-density laser to obtain a sufficient penetration depth, and using a high-density laser causes a large amount of metal vapor to be generated during welding, making it easier for it to be taken into the molten pool. . Under these circumstances, the above-described method, which can effectively suppress the inclusion of metal vapor in the molten pool as described above, can be suitably applied to the joining of the pump body 1 of a high-pressure pump and parts to be assembled therewith. .

-Modification-
In the above embodiment, the case where the invention is applied to the joint between the pump body 1 of the high-pressure pump and the discharge plug 8d was exemplified. can be applied and similar effects can be obtained. Moreover, the invention is applicable not only to high-pressure pumps but also to other products. For example, the present invention can be applied to a case where a fuel injection valve (such as the injector 24 in FIG. 1) is assembled and joined by welding, and the same effect can be obtained. In addition, although the so-called normally open high-pressure pump has been described in FIGS. 1-7, the present invention can also be applied to a normally closed high-pressure pump.

Also, in the above example, an example in which penetration welding is performed exactly at 360° was explained, but a slight increase or decrease in the range of penetration welding, for example, about 360±5° is allowed. This is because the molten pool formed by the laser LB is not a point but a three-dimensional volume with a circular cross section. Therefore, for example, the range of penetration welding may be limited to about 355°, and the energy of the laser LB may be rapidly reduced to non-penetration energy after 355° penetration welding. Also, an example in which the front bead 415 overlaps by 30° or more has been described, but this overlap amount is an example that is considered preferable, and the overlap amount OL2 of the front bead 415 can be appropriately changed in design.

Reference Signs List 1 Pump body 8d Discharge plug (mounted part, discharge valve body) 12c Discharge joint (mounted part) 411 Back bead start end 415 Front bead 416 Back bead A First first parts, B... second part, BW1, BW2... back bead width, LB... laser, OL1, OL2... overlap amount, WM... weld metal, φ... azimuth angle range

Claims

a first part having a through hole;
a second component inserted into the through hole of the first component;
an annular weld metal formed at opposing portions of the first component and the second component and joining the first component and the second component;
A joined product of two parts, wherein the amount of overlap between the start end and the end of the back bead of the weld metal is smaller than the width of the back bead.
The two-part joint of claim 1, wherein
A joined product of two parts, wherein the amount of overlap between the front end and the end of the front bead of the weld metal is larger than the width of the front bead.
The two-part joint of claim 2,
The overlapping part between the penetration weld part where the back bead is formed and the terminal part of the front bead has an azimuth angle range of 30 degrees or more between the starting end and the terminal end with respect to the center of the annular weld metal. A two-part joint characterized by:
The two-part joint of claim 3,
A joined product of two parts, wherein an overlapping portion between the through-welded portion and the end portion of the front bead has a melting depth shallower toward the end portion.
The two-part joint of claim 1, wherein
wherein the first component is a pump body of a high-pressure fuel pump;
A two-part joint, wherein the second part is a part assembled to the pump body.
The two-part joint of claim 5,
A two-part joint, wherein said second part is the body of a discharge valve.
A method of manufacturing a two-part joint according to claim 2, comprising:
moving the laser from the beginning of the front bead along the opposing portions of the first part and the second part while increasing the energy;
From the beginning of the back bead where the energy of the laser reaches the set penetration energy at which the back bead is formed, along the opposing parts of the first component and the second component, the penetration energy is maintained and the let the laser go on for a week,
After switching the energy of the laser to a non-penetrating energy setting at which the back bead is not formed when the back bead reaches the end of the back bead,
moving the laser along opposing portions of the first and second parts while decreasing the energy from the non-penetrating energy;
A method for manufacturing a joined article, wherein when the laser reaches the end of the front bead, the irradiation of the laser is stopped to complete the welding.