Joint of two components and method for manufacturing same

Abstract

Provided is a two-component joint body having: a first component having a through-hole; a second component inserted into the through-hole of the first component; and a ring-shaped welding metal formed at a facing portion of the first component and the second component to join the first component and the second component, wherein the overlapping amount of the start end and the end of the back pass of the welding metal is smaller than the width of the back pass.

Description

Technical Field

[0001] This invention relates to a joint and a method for joining two components, and more particularly to a joint and a method for manufacturing the same, which emphasizes the sealing performance of the annular weld between two components. Background Technology

[0002] As a technique for inserting one component into another component and welding the two components along the outer periphery of the other component, for example, the technique described in Patent Document 1 is known.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2018 / 142930 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] Patent Document 1 discloses a through-weld that extends through the thickness of two plates, and the welded portion is formed in a ring shape. In such welding, sometimes the opposing surfaces of the two components are welded in more than one round, forming an overlap where the second round of weld metal overlaps a portion of the first round of weld metal. However, this overlap is prone to internal cracks or porosity.

[0008] The purpose of this invention is to provide a joint of two components capable of suppressing the generation of internal cracks or pores in the weld metal that joins the two components, and a method for manufacturing the same.

[0009] Technical means to solve the problem

[0010] To achieve the above objective, the present invention provides a joint of two components, comprising: a first component having a through hole; a second component inserted into the through hole of the first component; and an annular weld metal formed on the opposing portions of the first component and the second component to join the first component and the second component, wherein the overlap between the beginning and end of the back weld bead of the weld metal is smaller than the width of the back weld bead.

[0011] The effects of the invention

[0012] According to the present invention, it is possible to suppress the formation of internal cracks or pores in the weld metal that joins two components. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a fuel supply system comprising a high-pressure fuel supply pump, which is an application example of a joint comprising two components as an embodiment of the present invention and a method for manufacturing thereof.

[0014] Figure 2 for Figure 1 The diagram shows a cross-sectional view of the high-pressure fuel supply pump.

[0015] Figure 3 for Figure 2 The view section below line III-III in the diagram.

[0016] Figure 4 for Figure 3 A cross-sectional view along line IV-IV in the diagram.

[0017] Figure 5 for Figure 3 The view section diagram along the VV line.

[0018] Figure 6 for Figure 4 Enlarged view of section VI.

[0019] Figure 7 To indicate Figure 6 An enlarged view of the area shown before welding.

[0020] Figure 8 A conceptual diagram illustrating the mechanism by which keyholes are generated due to the vapor pressure of metal vapor during welding.

[0021] Figure 9A A diagram illustrating the formation mechanism of solidification cracks in welded metal.

[0022] Figure 9B A diagram illustrating the formation mechanism of solidification cracks in welded metal.

[0023] Figure 9C A diagram illustrating the formation mechanism of solidification cracks in welded metal.

[0024] Figure 9D A diagram illustrating the formation mechanism of solidification cracks in welded metal.

[0025] Figure 9E A diagram illustrating the formation mechanism of solidification cracks in welded metal.

[0026] Figure 10 This is an explanatory diagram of a method for joining two components according to an embodiment of the present invention.

[0027] Figure 11A for Figure 10 A diagram illustrating the phenomena occurring at each stage of the joining method.

[0028] Figure 11B for Figure 10 A diagram illustrating the phenomena occurring at each stage of the joining method.

[0029] Figure 11C for Figure 10 A diagram illustrating the phenomena occurring at each stage of the joining method.

[0030] Figure 11D for Figure 10 A diagram illustrating the phenomena occurring at each stage of the joining method.

[0031] Figure 12A This is a schematic diagram of the back weld bead of a joint of two components manufactured by a manufacturing method according to an embodiment of the present invention.

[0032] Figure 12B for Figure 12A An enlarged view of section XIIB in the image. Detailed Implementation

[0033] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0034] Furthermore, sometimes the vertical direction is specified for explanation, but this vertical direction does not refer to the vertical direction when the high-pressure fuel supply pump is installed.

[0035] -Fuel Supply System-

[0036] Figure 1 This is a schematic diagram of a fuel supply system comprising a high-pressure fuel supply pump, which is an application example of a joint comprising two components as an embodiment of the present invention and a method for manufacturing thereof. Hereinafter, the high-pressure fuel supply pump will be abbreviated as high-pressure pump. The high-pressure pump illustrated in this embodiment is used in an engine system that directly injects fuel into the engine block.

[0037] The dashed box in the figure represents the main body of the high-pressure pump, namely the pump body 1. The mechanisms and components shown in the box are integrally mounted on the pump body 1. The feed pump 21 is driven by signals from the engine control unit 27 (hereinafter referred to as ECU) to draw fuel from the fuel tank 20. The fuel is pressurized and delivered to the fuel intake port 10a of the high-pressure pump via the intake pipe 28 at a specified feed pressure. After passing through the fuel intake port 10a, the fuel passes through the intake connector 51, the pressure pulsation reduction mechanism 9, and the intake passage 10d to reach the intake port 31b of the electromagnetic intake valve unit 300, which constitutes the variable capacity mechanism.

[0038] Fuel flowing into the electromagnetic intake valve unit 300 flows into the pressurization chamber 11 via the intake valve 30. This is facilitated by the engine's cam 93. Figure 2A reciprocating motion is applied to the plunger 2. During the reciprocating motion of the plunger 2, fuel is drawn from the intake valve 30 into the pressurization chamber 11 during the downward stroke of the plunger 2, and the fuel is pressurized during the upward stroke. The pressurized fuel in the pressurization chamber 11 is discharged from the high-pressure pump via the discharge valve 8 and the fuel discharge port 12 and sent to the common rail 23. A pressure sensor 26 and multiple injectors 24 are installed on the common rail 23. The injectors 24 are installed on the common rail 23 in a number corresponding to the number of cylinders of the internal combustion engine, and are opened and closed according to the control signal from the ECU 27, injecting fuel into the cylinders (combustion chamber) of the engine by opening. The fuel discharge flow rate of the high-pressure pump is adjusted by the control of the electromagnetic intake valve unit 300 by the ECU 27.

[0039] When a malfunction of injector 24 causes excessive pressure rise in the common rail 23, resulting in the differential pressure between the fuel outlet 12 and the pressurization chamber 11 exceeding the opening pressure of the relief valve unit 200, the ball valve 202 opens. The excessively pressurized fuel passes through the relief valve unit 200 and is returned to the pressurization chamber 11 from the relief channel 200a, thereby protecting high-pressure pipelines such as the common rail 23.

[0040] -High-pressure pump-

[0041] Figure 2 for Figure 1 The diagram shown is a cross-sectional view of the high-pressure fuel supply pump. Figure 3 for Figure 2 The view section below line III-III in the middle. Figure 4 for Figure 3 A cross-sectional view along line IV-IV in the diagram.

[0042] like Figure 3 and Figure 4 As shown, in this embodiment, the high-pressure pump is fixed to the outer wall of the cylinder head 90 of the internal combustion engine by means of multiple bolts (not shown). An O-ring 61 is embedded in the pump body 1, and the cylinder head 90 and the pump body 1 are sealed by the O-ring 61 to prevent oil leakage.

[0043] like Figure 3 As shown, a suction connector 51 is installed on the pump body 1. The suction connector 51 is connected to the suction pipe 28 that supplies low-pressure fuel from the vehicle's fuel tank 20. Figure 1Fuel is supplied from here to the high-pressure pump. Fuel flowing in from the fuel inlet 10a of the suction connector 51 flows through a low-pressure flow path formed inside the pump body 1 to a buffer chamber formed in the upper part 10b and lower part 10c of the buffer. The buffer chamber is defined by a buffer cover 14 installed on the pump body 1. The fuel flowing into the buffer chamber has its pressure pulsation suppressed by a pressure pulsation reduction mechanism 9 provided inside the buffer chamber, and reaches the suction port 31b of the electromagnetic suction valve unit 300 via the suction channel 10d. The pressure pulsation reduction mechanism 9 is a metal diaphragm buffer formed by bonding two corrugated disc-shaped metal plates together and injecting an inert gas (such as argon) inside. The expansion and contraction of the metal buffer absorbs and reduces the pulsation of fuel flow. Figure 3 The example shown is a configuration in which the suction connector 51 is located on the side of the pump body 1, and the suction connector 51 is sometimes also located on the upper surface of the buffer cover 14.

[0044] The pump body 1 is equipped with an electromagnetic suction valve unit 300 and a discharge valve 8. Fuel is supplied to the pressure chamber 11 via the pressure chamber inlet flow path 1a formed on the pump body 1 through the electromagnetic suction valve unit 300. The discharge valve 8 prevents fuel already discharged from the pressure chamber 11 from flowing into the discharge passage 12b. Figure 3 The fuel flows back through the discharge valve 8. The fuel after the discharge valve 8 passes through the fuel outlet 12 of the discharge connector 12c and is supplied to the engine.

[0045] Furthermore, a cylinder 6 is mounted on the pump body 1 to guide the reciprocating motion of the plunger 2. The cylinder 6 is pressed into the pump body 1 and secured by compression. The pressing of the cylinder 6 provides a seal to prevent pressurized fuel from leaking from the pressurization chamber 11 through the space between the cylinder 6 and the pump body 1. Moreover, the cylinder 6 contacts the pump body 1 not only on its outer peripheral surface but also on its upper end surface; the metal-to-metal contact between the upper end surface of the cylinder 6 and the pump body 1 further contributes to the sealing of the pressurized fuel.

[0046] A tappet 92 is provided at the lower end of the plunger 2. The rotational motion of the cam 93 mounted on the camshaft of the internal combustion engine is converted into up-and-down motion by the tappet 92 and transmitted to the plunger 2. A fastener 15 is installed on the plunger 2, and the fastener 15 is pressed by the spring 4 to press the plunger 2 onto the tappet 92. As a result, the plunger 2 moves up and down reciprocally with the rotational motion of the cam 93.

[0047] Furthermore, a plunger seal 13 is held at the lower end of the inner circumference of the seal holder 7, and this plunger seal 13 is located on the lower side of the cylinder block 6 in the figure. The plunger seal 13 slidably contacts the outer circumference of the plunger 2, thereby sealing the fuel in the secondary chamber 7a when the plunger 2 slides, thus preventing fuel from flowing into the internal combustion engine. At the same time, the plunger seal 13 also prevents lubricating oil (including engine oil) that lubricates the sliding parts inside the internal combustion engine from flowing into the pump body 1.

[0048] The discharge valve 8, located at the outlet of the pressurization chamber 11, consists of a valve seat 8a, a valve core 8b, a spring 8c, a discharge valve plug 8d, and a discharge valve stop 8e. The valve core 8b is forced against the valve seat 8a by the spring 8c, and the discharge valve 8 is opened and closed by the valve core 8b contacting and separating from the valve seat 8a. The stroke (distance of movement) of the valve core 8b is defined by the discharge valve stop 8e. The discharge valve plug 8d forms the main body of the discharge valve 8 and is joined to the pump body 1 by means of a weld metal 407. The weld metal 407 separates the inner space of the pump body 1, from the outer space of the pump body 1, from the inner space of the pump body 1, from the outer space of the pump body 1.

[0049] When there is no pressure difference between the pressurization chamber 11 and the discharge valve chamber 12a, the valve core 8b is pressed against the valve seat 8a by the spring 8c, and the discharge valve 8 is in a closed state. When the fuel pressure in the pressurization chamber 11 becomes significantly higher than the fuel pressure in the discharge valve chamber 12a, the valve core 8b moves against the spring 8c, and the discharge valve 8 opens. At this time, the high-pressure fuel in the pressurization chamber 11 passes through... Figure 3 The discharge valve chamber 12a, discharge passage 12b, and fuel outlet 12 shown discharge fuel to the common rail 23. Figure 1 Furthermore, the opening and closing movement of the valve core 8b is guided and limited in the stroke direction by the outer peripheral surface of the discharge valve stop 8e, and the discharge valve 8 also functions as a check valve.

[0050] The pressurization chamber 11 is defined by the pump body 1, the electromagnetic suction valve unit 300, the plunger 2, the cylinder 6, the discharge valve 8, and the overflow valve unit 200. The rotation of the cam 93 causes the plunger 2 to reciprocate. When the plunger 2 moves in the direction of expanding the volume of the pressurization chamber 11, fuel is drawn into the pressurization chamber 11, reducing the fuel pressure inside the pressurization chamber 11. When the fuel pressure inside the pressurization chamber 11 becomes lower than the pressure in the suction channel 10d during this stroke, the suction valve 30 opens.

[0051] After the intake stroke, plunger 2 changes direction of motion towards reducing the pressure chamber 11, thus entering the compression stroke. Here, without energizing the solenoid coil 43 of the solenoid intake valve unit 300, the intake valve 30 is opened by the valve stem force spring 40. With the volume of the pressure chamber 11 reduced, the fuel already drawn into the pressure chamber 11 is temporarily returned to the intake passage 10d through the opening of the intake valve 30, so the pressure in the pressure chamber 11 does not rise. This stroke is called the return stroke.

[0052] Next, use Figure 5 The electromagnetic suction valve unit 300 will be described below. Figure 5 for Figure 3 The cross-sectional view below the VV line shows the state in which the intake valve is open.

[0053] The electromagnetic intake valve unit 300 drives the intake valve 30, which is arranged side-by-side with the magnetic core (fixed core) 39, the movable core 36, and the valve stem 35, by energizing the electromagnetic coil 43, thereby drawing in fuel and delivering it to the pressurization chamber 11. In the de-energized state, the intake valve 30 is pushed in the opening direction by the valve stem force spring 40. When a control signal from the ECU 27 is applied to the electromagnetic intake valve unit 300, current flows through the terminal 46 to the electromagnetic coil 43, and the magnetic core 39 generates a magnetic attraction force. Simultaneously, on the magnetic attraction surface S, the movable core 36 is pulled in the closing direction by the magnetic attraction force of the magnetic core 39. The valve stem 35 is disposed between the movable core 36 and the intake valve 30, and has a flange portion 35a that engages with the movable core 36. The electromagnetic coil chamber, where the electromagnetic coil 43 is located, is covered by a cover member 44, and the magnetic core 39 also serves as a component of the cover member 44. The valve stem force-applying spring 40 is partially covered by the retaining cover member 44 of the magnetic iron core 39.

[0054] The valve stem 35 is engaged with the movable iron core 36 by a flange 35a, and moves together with the movable iron core 36 when the movable iron core 36 moves toward the magnetic iron core 39. Therefore, when the magnetic attraction force acts on the movable iron core 36, the valve stem 35 moves toward the valve closing direction. A valve closing force spring 41 that applies force to the movable iron core 36 in the valve closing direction and a valve stem guide member 37 that guides the valve stem 35 in the valve opening and closing direction are arranged between the movable iron core 36 and the suction valve 30. The valve stem guide member 37 constitutes the spring seat 37b of the valve closing force spring 41. In addition, a fuel passage 37a is provided on the valve stem guide member 37, so that fuel can flow in and out of the space where the movable iron core 36 is arranged.

[0055] The movable iron core 36, the valve closing force spring 41, and the valve stem 35 are enclosed within the electromagnetic suction valve unit housing 38, which is fixed to the pump body 1. Furthermore, the magnetic iron core 39, the valve stem force spring 40, the electromagnetic coil 43, and the valve stem guide member 37 are supported on the electromagnetic suction valve unit housing 38. The valve stem guide member 37 is mounted on the side of the electromagnetic suction valve unit housing 38 opposite to the magnetic iron core 39 and the electromagnetic coil 43. This valve stem guide member 37 encloses the suction valve 30, the suction valve force spring 33, and the stop member 32, forming part of the electromagnetic suction valve unit housing 38.

[0056] The intake valve 30, intake valve force spring 33, and stop member 32 are mounted on the opposite side of the magnetic core 39 on the valve stem 35. The intake valve 30 has a guide portion 30b protruding towards the pressurization chamber 11, which is guided by the intake valve force spring 33. As the valve stem 35 moves, the intake valve 30 moves its valve core stroke 30e in the opening direction (away from the valve seat 31a) to become open, supplying fuel from the intake passage 10d to the pressurization chamber 11. The guide portion 30b stops moving by colliding with the stop member 32. The stop member 32 is pressed into and fixed inside the housing (valve stem guide member 37) of the electromagnetic intake valve unit 300. The valve stem 35 and the intake valve 30 are independent components.

[0057] The intake valve 30 closes the flow path to the pressurization chamber 11 by contacting the valve seat 31a of the valve seat member 31 disposed on the intake side, and opens the flow path to the pressurization chamber 11 by moving away from the valve seat 31a. When the magnetic force overcomes the force of the valve stem spring 40 and causes the valve stem 35 to move away from the intake valve 30, the force of the intake valve spring 33 and the fluid force of the fuel flowing into the intake passage 10d cause the intake valve 30 to close. After the valve closes, the volume of the pressurization chamber 11 decreases due to the action of the plunger 2, and the fuel pressure in the pressurization chamber 11 increases. When the pressure in the pressurization chamber 11 becomes higher than the pressure at the fuel outlet 12, high-pressure fuel is discharged from the high-pressure pump via the discharge valve 8 and supplied to the common rail 23. This stroke is called the discharge stroke. The fuel discharged from the high-pressure pump can be controlled by the timing of energizing the solenoid coil 43.

[0058] The relief valve unit 200 comprises a relief valve sleeve 201, a ball valve 202, a relief valve pressure block 203, a spring 204, and a spring seat 205. The relief valve unit 200 opens the ball valve 202 to return fuel to the pressurization chamber 11 only when a problem occurs in the common rail 23 or a component downstream of it, exceeding the allowable value and becoming high pressure.

[0059] -Welding Metal-

[0060] The pump body 1 has multiple through holes for component assembly. Assembly components are inserted into these through holes and joined by welding. Examples include the discharge valve 8 and the discharge connector 12c. The main body of the discharge valve 8 (discharge plug 8d) and the discharge connector 12c are joined to the pump body 1 via weld metal 407 formed by laser welding. The weld metal 407 forms a ring around the outer periphery of the discharge plug 8d, along the opposing portion of the pump body 1 and the discharge plug 8d. Similarly, the weld metal 407 joining the discharge connector 12c to the pump body 1 forms a ring around the outer periphery of the discharge connector 12c, along the opposing portion of the pump body 1 and the discharge connector 12c. Suppressing the formation of defects such as solidification cracks or porosity within these weld metals 407 is important from the perspective of ensuring the reliability of the welded parts. In particular, the reliability of the welded parts facing the fuel flow path inside the pump body 1 is important from the perspective of preventing fuel leakage from the pump body 1; therefore, the welded parts need sufficient strength.

[0061] Figure 6 for Figure 4 An enlarged view of section VI, specifically an enlarged view of the welded joint between pump body 1 and discharge plug 8d. Furthermore, Figure 7 To indicate Figure 6 An enlarged view of the area shown before welding. Here, [the image is] enlarged. Figure 6 and Figure 7 The structure of the welded part between the pump body 1 and the discharge plug 8d will be described, and the welded part between the pump body 1 and the discharge connector 12c has the same structure.

[0062] like Figure 7 As shown, the discharge plug 8d, which is inserted into the through hole 413 formed on the pump body 1 for component assembly, is pressed into and fixed to the pump body 1 by a separately formed press-in portion 405, distinct from the welding pre-welding portion (the portion that forms weld metal 407 after welding). The press-in portion 405 is located on the inner side of the pump body 1 relative to the welding pre-welding portion 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 pressed into the pump body 1 until the flange 414 touches the press-in receiving surface 406 of the outer wall of the pump body 1. In the stage before welding, there is a small 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 facing it, which is different from the press-in portion 405. This gap GP is a conical shape that tapers towards the inside of the pump body 1. Figure 7 Viewed from the cross-section, it is inclined relative to the centerline O as it moves towards the centerline O of the discharge plug 8d as it goes into the pump body 1. Furthermore, a gap 400 is formed between the gap GP (the opposing portion of the pump body 1 and the discharge plug 8d) and the pressing portion 405. When the pump body 1 and the discharge plug 8d are welded, Figure 7In the state of alignment, the laser LB is irradiated onto the laser irradiation surface 404 of the flange 414 of the discharge plug 8d, and the laser LB is made to rotate along the annular gap GP. Figure 7 In the cross section, the optical axis of the laser LB is tilted relative to the center line O of the discharge plug 8d due to the tilt of the gap GP.

[0063] The result of the welding is as follows: Figure 6 As shown, the opposing portions of the pump body 1 and the discharge plug 8d melt and solidify around the area where the gap GP previously existed, forming weld metal 407 that joins the pump body 1 and the discharge plug 8d. Because of the gap 400, in addition to the surface weld bead 415 (the space exposed outside the pump body 1) formed on the incident side of the laser LB, a back weld bead 416 exposed outside the gap 400 is also formed on the weld metal 407. Figure 6 In the cross-section, the straight line 407a passing through the center of the width direction of the surface weld 415 and the center of the width direction of the back weld 416 corresponds to the gap GP before welding and is inclined relative to the center line O of the discharge plug 8d. The weld metal 407 is formed on the entire circumference of the discharge plug 8d, and the opposing portions of the pump body 1 and the discharge plug 8d are sealed by the weld metal 407, thereby preventing fuel leakage from the pump body 1.

[0064] -Mechanisms of Defect Generation in Welded Metal-

[0065] Figure 8 This is a conceptual diagram illustrating the mechanism of keyhole formation caused by the vapor pressure of metal vapor during welding. As shown in the diagram, when a metal component is irradiated with a laser (LB), the metal component melts due to the heating effect of the laser LB, reaching its melting point. A portion of the metal component becomes liquid, forming a molten pool (MP). Subsequently, the metal component near the laser axis of the liquefied molten pool (MP) is further heated by the laser LB, causing it to evaporate and become metal vapor (MV). It is assumed that the vapor pressure of this metal vapor (MV) pushes open the molten pool (MP), forming a keyhole (KH). Furthermore, the keyhole (KH) is not immediately generated upon irradiation of the metal component with the laser LB, but rather occurs through the stages of molten pool (MP) formation and metal vapor (MV) generation. It is assumed that the laser LB penetrating the plate thickness (TP) of the metal component is a stage following the formation of the keyhole (KH). After the keyhole (KH) is formed, it gradually deepens with increasing laser LB energy, causing the molten pool (MP) to gradually deepen, thus penetrating the plate thickness (TP).

[0066] Figures 9A-9E These diagrams illustrate the phased formation mechanism of solidification cracks in welded metal. In these diagrams, the first component A (...) is shown... Figures 1-7 In the example, a second metal component B is pressed into the cylindrical through-hole TH of the pump body 1. Figures 1-7For example, consider the discharge plug 8d). Furthermore, the process of irradiating the opposing portions of the first component A and the second component B with laser LB and rotating the first component A and the second component B to scan the cylindrical opposing portions of the two components with laser LB is shown in [the diagram]. Figures 9A-9E middle.

[0067] exist Figures 9A-9E In the example, taking the center line O of the annular opposing portion (in other words, the gap GP) of component A and component B as a reference, the keyhole KH penetrates the plate thickness TP of component A and component B. Figure 8 The position of the through weld start point P1 is set at an azimuth angle θ = 0°. The through weld start point P1 becomes the beginning of the back weld 416. The molten pool MP and keyhole KH advance together with the laser LB in a circular trajectory from the through weld start point P1. The portion after the laser LB passes through solidifies sequentially to continuously form weld metal WM. Figure 9A This demonstrates the situation during the advance of the laser LB at an azimuth angle of 0°≤θ≤270°. During this period, a sufficient gap GP is maintained in the direction of laser LB's advance, and the metal vapor MV generated inside the keyhole KH flows into the gap GP in the laser's advance direction. As the laser LB advances further and resembles... Figure 9B As shown, when the laser LB reaches the region with an azimuth angle θ ≥ 270°, as it approaches the point P1 where the welded metal WM is fully occupied during the through weld, the gap GP in the laser LB's forward direction gradually disappears. When the laser LB further approaches the point P1 where the through weld begins, as... Figure 9C As shown, a portion of the metal vapor MV in the gap GP, which was intended to flow into the forward direction of the laser LB, collided with the weld metal WM at the weld initiation point P1. Consequently, the metal vapor MV that collided with the weld metal WM was pushed back in the opposite direction of the laser LB's forward direction by the reaction force, like... Figure 9D As shown, it is contained within the molten pool MP. The solidification of the molten pool MP containing metal vapor MV will be like... Figure 9E As shown, pores are generated within the solder metal WM, which may lead to internal cracking of the solder metal WM IC.

[0068] -Manufacturing method of the joint--

[0069] In contrast, Figure 1-7 The weld metal 407 of the high-pressure pump, as described above, is formed using a special welding method designed to suppress the formation of such internal cracks. This results in the manufacture of a material equivalent to... Figures 9A-9E In the example, the pump body 1 of component A is securely joined to the discharge plug 8d (or discharge connector 12c) corresponding to component B. The manufacturing method of the joint of these two components includes a laser energy increasing process, a through welding process, a laser energy switching process, and a laser energy decreasing process.

[0070] The laser energy increase process is a process in which the laser is moved while increasing energy, starting from the beginning of the surface weld bead (the laser irradiation start position) along the opposing portions of the first and second components. During this process, the energy of the laser LB is increased until the set through energy is reached to form the back weld bead. In the laser energy increase process, the melting depth does not reach the plate thickness of the first and second components, so the back weld bead is not formed.

[0071] The next through-welding process begins at the point where the laser LB energy reaches the aforementioned through-energy level, which is the beginning of the back weld bead. The laser LB is maintained at this through-energy level and rotates around the opposing portions of the first and second components once. During this through-welding process, the melting depth reaches the thickness of the first and second components, thus forming the back weld bead.

[0072] The laser energy switching process following the through-welding process involves switching the laser LB energy to a non-through energy that will not form a back weld when the end of the back weld bead is reached (in other words, when returning to the beginning of the back weld bead after one through-welding cycle). As a result, the melting depth again fails to reach the plate thickness of the first and second components, and the back weld bead is interrupted at this point.

[0073] The laser energy reduction process is a process in which the laser LB moves along the opposing portions of the first and second components while reducing the energy from the non-through energy level after the laser energy switching process. During this period, as the energy of the laser LB decreases, the melting depth also becomes shallower, and the weld metal (second ring weld metal) becomes thinner. When the laser LB reaches the specified end position of the surface weld bead, the laser LB irradiation is stopped, and the welding is completed.

[0074] The following is a specific example of the manufacturing method of the above-described joint, using the accompanying drawings.

[0075] Figure 10 This is an explanatory diagram of a method for joining two components according to an embodiment of the present invention, showing the energy control of the laser LB in an example where the laser LB is irradiated clockwise along the annular opposing portion of the pump body 1 and the discharge plug 8d. Figures 11A-11D The figures are Figure 10 These diagrams illustrate the phenomena occurring at each stage of the joining method. The azimuth angles shown in these diagrams correspond to... Figures 9A-9E The azimuth angle shown. Here, we use... Figure 10 as well as Figures 11A-11D The welding of pump body 1 to discharge plug 8d is described, and the welding of pump body 1 to discharge connector 12c is the same.

[0076] first, Figure 10In this process, during the period when the laser LB advances along the annular opposing portion of the pump body 1 and the discharge plug 8d from the laser irradiation starting point X, the laser energy of the laser LB is increased from 0 to the aforementioned penetrating energy. This process of increasing the laser energy by the rotation angle Ru is the laser energy increasing process.

[0077] Subsequently, during the period when the laser LB advances further along the annular opposing portion of the pump body 1 and the discharge plug 8d by a formal welding rotation angle Fp (360°), the laser LB with penetrating energy performs a through weld on both the pump body 1 and the discharge plug 8d. This process within the formal welding rotation angle Fp is the through weld process. The back weld bead 416 is formed only within the formal welding rotation angle Fp. In this example, when the laser LB approaches the through weld start point P1, as... Figure 11A As shown, a portion of the metal vapor MV in the gap GP, which is intended to flow into the laser LB's forward direction, will also collide with the weld metal WM at the through-weld initiation point P1 (and...). Figure 9C Same).

[0078] After the formal welding rotation angle Fp, during the period when the laser LB further advances along the annular opposing portion of the pump body 1 and the discharge plug 8d, and the laser energy decreases by a sudden rotation angle Fd, the energy of the laser LB is switched from the penetrating energy to the aforementioned non-penetrating energy. This process within the range of the sudden reduction rotation angle Fd is the laser energy switching process. Here, for example, the sudden reduction rotation angle Fd is set to approximately 5-10°, and within this 5-10° range, the energy of the laser LB is reduced by approximately 15-20%. Thus, as... Figure 11B As shown, the keyhole KH shrinks, the amount of metal vapor MV inside the keyhole KH decreases, and the vapor pressure decreases, thus causing the metal vapor MV to remain in the keyhole KH.

[0079] After the energy of the laser LB is reduced to a non-penetrating energy, the energy of the laser LB is gradually reduced during the period when the laser LB advances along the annular opposing portion of the pump body 1 and the discharge plug 8d, reducing the laser energy by a rotation angle Rd. This process within the range of laser energy reduction rotation angle Rd is the laser energy reduction process. Thus, as... Figure 11C As shown, the metal vapor MV inside the keyhole KH is released into the atmosphere from the laser incident side. During this period, the keyhole KH disappears and the welding ends.

[0080] -Connector-

[0081] pass Figures 10-11DThe method described above manufactures a joint of two components comprising: a first component having a through hole; a second component inserted into the through hole of the first component; and an annular weld metal formed on the opposing portions of the first and second components, thereby joining the first and second components. Furthermore, by undergoing a laser energy switching process, a distinctive weld mark is left where the overlap between the beginning and end of the back weld bead is smaller than the width of the back weld bead.

[0082] On the other hand, by performing a laser energy reduction process following the laser energy switching process, the overlap between the beginning and end of the surface weld bead of the weld metal becomes greater than the width of the surface weld bead. Thus, the through weld portion forming the back weld bead overlaps with the end of the second ring of surface weld beads, resulting in an azimuth angle range of over 30 degrees between the beginning and end of this overlap portion, with the center of the annular weld metal as the reference. The melting depth of the overlap portion between the through weld portion and the end of the second ring of surface weld beads becomes shallower towards the end. Figures 1-7 In the high-pressure pump described above, the pump body 1 is equivalent to the first component mentioned here, and the components assembled on the pump body 1, such as the main body of the discharge valve, i.e., the discharge valve plug 8d (or discharge connector 12c), are equivalent to the second component.

[0083] The above-described assembly is illustrated using the accompanying drawings.

[0084] Figure 12A The manufacturing method according to one embodiment of the present invention ( Figure 10 A schematic diagram of the back weld bead of the joint of the two manufactured components. Figure 12B for Figure 12A An enlarged view of section XIIB in the image.

[0085] As mentioned earlier, the penetration depth only occurs at the formal welding rotation angle Fp ( Figure 10 The through-plate weld is performed within the range of ) to reach the plate thickness (through plate thickness), so only the back weld bead 416 is formed within this range. That is, only a 360° back weld bead 416 is formed. The through weld starts at the beginning of the range where the laser LB passes through the formal welding rotation angle Fp, which is the starting point P1 ( Figure 10 When the laser LB passes through the end of the interval of the formal welding rotation angle Fp, a back weld bead start portion 411 is formed. Furthermore, a back weld bead end portion 412 is formed when the laser LB passes through the end of the interval of the formal welding rotation angle Fp. Since the laser LB has a circular cross-section, the top ends 411a and 412a of the back weld bead start portion 411 and the back weld bead end portion 412 are respectively arc-shaped according to the cross-sectional shape of the laser LB. In this embodiment, the back weld bead start portion 411 and the back weld bead end portion 412 overlap only at their semi-circular top ends 411a and 412a, as shown below. Figure 12B As shown, the overlap OL1 is smaller than the weld width BW1 of the back weld 416.

[0086] On the other hand, relative to the back weld 416 which only forms the formal welding rotation angle Fp, a surface weld 415 is continuously formed within the interval of the laser energy increase rotation angle Ru, the formal welding rotation angle Fp, the laser energy decrease rotation angle Fd, and the laser energy decrease rotation angle Rd. Therefore, the end of the second round of surface weld 415 overlaps with the through weld portion formed within the interval of the combined laser energy decrease rotation angle Fd and laser energy decrease rotation angle Rd, which is within the interval of the formal welding rotation angle Fp. This overlap amount OL2 ( Figure 11D The weld width BW2 is greater than that of surface weld 415. Figure 11D Width. As mentioned above, the azimuth angle range φ( ) between the beginning and end of the overlapping portion of the surface weld bead 415 and the through weld portion. Figure 11D The temperature is above 30 degrees Celsius.

[0087] -Effect-

[0088] (1) According to this embodiment, as described above, after the through-welding begins, at the moment when the laser LB circles once around the opposing portions of the first and second components and returns to the through-welding start point P1, the energy of the laser LB is drastically reduced to a non-through-welding energy. As a result, the overlap OL1 between the beginning and end of the back weld bead of the weld metal is smaller than the weld bead width BW1 of the back weld bead. During the formation of this weld metal, after the step of drastically reducing the energy of the laser LB to a non-through-welding energy, as described above, the metal vapor MV is drastically reduced and remains inside the keyhole KH, thereby suppressing the phenomenon where the molten pool MP encapsulates and solidifies the metal vapor MV. Thus, the generation of internal cracks or pores in the weld metal joining the two components can be suppressed, thereby expecting effects such as improved reliability of the joint of the two components and reduced maintenance costs for weld quality in mass production. Since internal cracks in the weld metal are effectively suppressed, high-pressure fuel can be effectively sealed using the weld metal.

[0089] (2) In this embodiment, the back weld bead of the weld metal overlaps only at the end. In contrast, the overlap amount OL2 of the surface weld bead of the weld metal is larger than the weld bead width BW2 of the surface weld bead 415. In particular, in this embodiment, the overlap between the through weld portion of the weld metal and the end portion of the surface weld bead is ensured to be over a wide range of azimuth angles of 30 degrees or more, so the two parts can be firmly joined, and the reliability of the joint strength of the two parts is also fully ensured. At this time, by completing the welding through a laser energy reduction process in such a way that the melting depth of the overlap portion between the through weld portion and the end portion of the surface weld bead becomes shallower towards the end, the generation of porosity in the overlap portion can also be more effectively suppressed.

[0090] (3) As described in the above embodiment, the above method can be appropriately applied to the joint between the pump body 1 of the high-pressure fuel pump and the components mounted thereon (e.g., the discharge plug 8d), especially the portion facing the high-pressure fuel. Specifically, since the inside of the pump body 1 of the high-pressure pump is under high pressure, the sealing performance of the assembly components such as the discharge plug 8d is also important from the viewpoint of suppressing fuel leakage, and sometimes methods such as... Figure 6 and Figure 7 As explained earlier, the structure is securely fixed through interference fit and welding. However, manufacturing the component in a way that ensures precise contact between the pump body 1 and the opposing surfaces of the mounting parts at both the interference fit and welded portions is not easy in terms of precision. Therefore, sometimes... Figure 7 As explained above, the parts to be welded are designed with a gap fit. However, in this case, a high-density laser must be used to obtain sufficient melting depth. Using a high-density laser can easily lead to the generation of a large amount of metal vapor during welding, which enters the molten pool. For this reason, as described above, the method that can effectively suppress the presence of metal vapor in the molten pool can be appropriately applied to the joint between the pump body 1 of the high-pressure pump and the components mounted on it.

[0091] -Variations-

[0092] The above embodiments illustrate the application of the invention to the engagement of the pump body 1 of the high-pressure pump and the discharge plug 8d. However, as described above, the invention can also be applied to the engagement of the pump body 1 of the high-pressure pump and the discharge connector 12c to achieve the same effect. Furthermore, the invention is not limited to high-pressure pumps; it can be applied to other products as well. For example, it can also be applied to fuel injection valves (…). Figure 1 When the present invention is applied to a case where the injector 24, etc., is joined by welding, the same effect will be achieved. Furthermore, Figure 1-7 The invention describes a normally open high-pressure pump, but it can also be applied to normally closed high-pressure pumps.

[0093] Furthermore, the above examples illustrate a 360° through-weld, but variations in the through-weld area, such as approximately 360 ± 5°, are permissible. This is because the molten pool formed by laser LB is not a point but a three-dimensional entity with a circular cross-section and volume. Therefore, for example, the through-weld area can be limited to approximately 355°, and the laser LB energy can be drastically reduced to a non-through-weld energy at the 355° through-weld position. Additionally, an example of overlapping surface weld beads 415 by more than 30° has been described, but this overlap is considered appropriate, and the overlap amount OL2 of surface weld beads 415 can be modified as appropriate.

[0094] Symbol Explanation

[0095] 1…Pump body, 8d…Discharge plug (the assembled component, the main body of the discharge valve), 12c…Discharge connector (the assembled component), 411…Starting end of the back weld, 415…Surface weld, 416…Back weld, A…First component, B…Second component, BW1, BW2…Width of the back weld, LB…Laser, OL1, OL2…Overlap, WM…Weld metal, φ…Azimuth range.

Claims

1. A joint of two components, characterized in that, have: The first component has a through hole; The second component is inserted into the through hole of the first component; and A ring-shaped weld metal, formed at the opposing portions of the first and second components, joins the first and second components. The overlap between the beginning and end of the back weld bead of the weld metal is smaller than the width of the back weld bead. The overlap between the beginning and end of the surface weld bead of the weld metal is greater than the width of the surface weld bead.

2. The joint of the two components according to claim 1, characterized in that, Regarding the overlapping portion of the through weld portion where the back weld bead is formed and the end portion of the surface weld bead, the azimuth angle between the beginning and the end of the annular weld metal is 30 degrees or more, with the center of the annular weld metal as a reference.

3. The joint of the two components according to claim 2, characterized in that, The melting depth of the overlapping portion between the through weld and the end portion of the surface weld decreases towards the end.

4. The joint of the two components according to claim 1, characterized in that, The first component is the pump body of the high-pressure fuel pump. The second component is a component assembled on the pump body.

5. The joint of the two components according to claim 4, characterized in that, The second component is the main body of the discharge valve.

6. A method for manufacturing a joint, wherein the joint is a joint of two components according to claim 1, characterized in that, Starting from the beginning of the surface weld bead, the laser is moved along the opposing portions of the first and second components while increasing the energy. Starting from the beginning of the back weld bead, where the laser energy reaches the set penetrating energy to form the back weld bead, the laser maintains the penetrating energy along the opposing portions of the first component and the second component, causing the laser to circle once. When the laser reaches the end of the back weld bead, the energy is switched to a non-penetrating energy that will not form the back weld bead. Then, while reducing the energy from the non-penetrating energy, the laser is moved along the opposing portions of the first component and the second component. When the laser reaches the end of the surface weld bead, the laser irradiation is stopped and the welding is completed.

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