JP2004114108A - Method and equipment for welding metallic member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid decrease of productivity and increase in equipment investment by preventing metallic powder from sticking to a valve seat member and by performing welding and demagnetizing of the valve seat member by means of the same equipment. <P>SOLUTION: In the welding process, a welding current of about 90 kA×1 pulse (0.1 to 0.6 sec) is fed in the positive direction. After the welding process, a reheating current of about 30 to 50 kA×1 to 5 pulses (0.1 to 3.0 sec) lower than the welding current is fed in the negative direction (reverse direction) for reheating the valve seat member by the resistance heat generation. Thereby a hardened layer inside the valve seat member is tempered, and simultaneously the magnetic force of the magnetized valve seat member is relaxed by generating a magnetic field in the reverse direction as compared with that of the welding process. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for joining a metal member to join an annular valve seat member to a supply / exhaust port portion of a cylinder head in an automobile engine, for example.
[0002]
[Prior art]
BACKGROUND ART Conventionally, a technique of joining an annular valve seat member to a supply / exhaust port portion of a cylinder head in an automobile engine using heat generated by electric resistance of an electrode portion has been put into practical use (for example, see Patent Document 1).
[0003]
In addition, the hardness of the newly joined valve seat members is increased by performing the tempering on the already joined valve seat members due to the resistance heat generated at the time of the new joining, including the already joined valve seat members in the energizing path at the time of joining the newly joined valve seat members. A technique for suppressing the rise has been proposed (for example, see Patent Document 2).
[0004]
[Patent Document 1]
JP 2000-263243 A (FIG. 7)
[Patent Document 2]
JP-A-11-90653 (FIG. 20)
[Problems to be solved by the invention]
By the way, according to the technology described in the above publication, a high heating resistance and a strong magnetic field are generated because a current of about 90 kA is applied. And, the higher the resistance heat is, the more rapidly the joint portion is cooled together with the stop of energization, so that the valve seat member is quenched and the hardness (about Hv550) is increased, and the workability in the post-process such as cutting is deteriorated. However, wear of cutting tools and the like is also accelerated, leading to a decrease in productivity and an increase in cost.
[0005]
In addition, when a strong magnetic field is applied to magnetize the valve seat member, which is a magnetic material, metal powder or the like adheres to the valve seat member, causing problems such as abnormal wear of the valve seat member or the valve during operation of the engine.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to prevent metal powder from adhering to a valve seat member, and furthermore, it is possible to perform joining, tempering and demagnetization of the valve seat member with the same apparatus. Another object of the present invention is to provide a method and an apparatus for joining metal members, which can avoid a decrease in productivity and an increase in capital investment.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems and achieve the object, a method for joining metal members according to the present invention includes the steps of: heating a first metal member having magnetism by generating heat with electric resistance by energization and pressing by an electrode portion; A joining step of joining to the second metal member having a lower melting point; and a demagnetization step of demagnetizing the first metal member after the joining.
[0008]
Preferably, in the above method, the demagnetization step includes a tempering treatment in which a current value lower than a current value applied in the bonding step and a current in the opposite direction is applied to reheat.
[0009]
Preferably, in the above method, the joining step is performed in a cooling liquid.
[0010]
Preferably, in the above method, the first metal member is an iron-based valve seat member, and the second metal member is a cylinder head made of an aluminum alloy.
[0011]
The joining device for a metal member according to the present invention includes a joining unit that joins a first metal member having magnetism by generating heat with electric resistance by energization and pressing by an electrode unit to a second metal member having a lower melting point than the first metal member. And demagnetizing means for demagnetizing the first metal member after the joining.
[0012]
Preferably, in the above-mentioned apparatus, the demagnetizing means performs tempering by re-heating by supplying a current having a value lower than a current value supplied by the joining means and in a reverse direction.
[0013]
【The invention's effect】
As described above, according to the first and fifth aspects of the present invention, the first metal member having a magnetism and having a lower melting point than the first metal member is made to generate heat by electric resistance by energization and pressing by the electrode portion. By joining to the member and demagnetizing the first metal member after joining, adhesion of metal powder or the like to the first metal member can be suppressed, and problems such as abnormal wear can be eliminated.
[0014]
According to the second and sixth aspects of the present invention, the same device is used for joining, tempering, and demagnetizing the valve seat member by applying a current lower than the electric current applied at the time of joining and applying a current in the opposite direction to reheat. And a decrease in productivity and an increase in capital investment can be avoided.
[0015]
Further, by the tempering treatment, the quenched and hardened layer of the first metal member quenched at the time of joining is tempered to suppress an increase in hardness.
[0016]
According to the third aspect of the present invention, since the joining is performed in the coolant, the workability by tempering is remarkably improved in the joining in the coolant in which the first metal member is easily quenched.
[0017]
According to the invention of claim 4, since the first metal member is an iron-based valve seat member and the second metal member is a cylinder head made of an aluminum alloy, adhesion of metal powder or the like to the first metal member is achieved. Is suppressed, and abnormal wear of the valve seat member or the valve can be prevented. Furthermore, the joining, tempering, and demagnetization of the valve seat member can be performed by the same device, so that a decrease in productivity and an increase in equipment investment can be avoided.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0019]
The embodiment described below is an example as a means for realizing the present invention, and the present invention can be applied to a modification or modification of the following embodiment without departing from the gist thereof.
[0020]
[Metal member joining device]
FIG. 1A shows an overall configuration of a metal member joining apparatus according to an embodiment of the present invention (hereinafter, referred to as a joining apparatus), and FIG. 1B shows a metal member joining apparatus of an embodiment according to the present invention. FIG. 2 is a diagram showing an electrical configuration of the embodiment. FIG. 2 is a cross-sectional view illustrating a configuration of an electrode unit of the bonding device of FIG. FIG. 3 is a sectional view showing a positional relationship between a valve seat member and a cylinder head joined by the joining device of FIG.
[0021]
In FIG. 1A, a joining device 1 includes a transformer 12 as a transformer provided on a base 11, and a stage 13 movably provided in a two-dimensional direction on the base 11 beside the transformer 12. The cylinder head 15 is disposed inside a water tank 14 filled with a cooling liquid 33 held on the stage 13.
[0022]
Further, on the side of the transformer 12 and above the cylinder head 15, an electric resistance welding unit 16 electrically connected to the transformer 12 is provided. An electrode section 19 is attached via a platen 18.
[0023]
As shown in FIG. 1B, power is supplied to the transformer 12 via a power supply unit 41. The power supply unit 41 includes, for example, a first capacitor 43 that accumulates a charge for causing a current to flow in the positive direction from the power supplied from the AC 200 V power supply 42 to the electrode portion 19, and a negative capacitor in the negative direction with respect to the electrode portion 19. A second capacitor 44 for storing a charge for flowing a current, and a connection between the first capacitor 43 or the second capacitor 44 and the transformer 12 are switched to supply currents in opposite directions, and the magnitude of the current is pulsed. A switching control unit 45 that controls the width.
[0024]
The switching control unit 45 can set the direction of current supply and the magnitude of the current with the operation unit 46.
[0025]
For convenience of explanation, the direction of the current at the time of bonding is a positive direction, and the direction of the current at the time of demagnetization and tempering is a negative direction.
[0026]
Further, instead of the configuration using a capacitor, the power supply unit 41 may be configured to generate a current in the opposite direction by alternating current.
[0027]
As described later with reference to FIGS. 4 to 6, the switching control unit 45 of the power supply unit 41 supplies a pulse current of about 90 kA × 1 pulse (0.1 to 0.6 seconds) at the time of joining (hereinafter, joining current). After the joining, a pulse current of about 30 to 50 kA × 1 to 5 pulses (0.1 to 3.0 seconds) lower than the joining current (hereinafter referred to as reheating current) is applied in the negative direction. A current is applied in the opposite direction (reverse direction), and the valve seat member 20 is reheated by the resistance heat, thereby tempering the hardened layer inside the valve seat member. At this time, a magnetic field in the opposite direction to that at the time of joining is simultaneously generated to relax the magnetized magnetic force of the valve seat member 20 (demagnetization processing).
[0028]
That is, by providing the power supply unit 41 to the joining device, the joining device has a function of joining, tempering, and demagnetizing the valve seat member 20.
[0029]
As shown in FIG. 2, an annular valve seat member 20 is detachably held at the lower end of the electrode portion 19 by the magnetic force of a magnet (not shown). The cylinder head 15 is made of, for example, an aluminum alloy that is a conductive material, and the valve seat member is made of, for example, a sintered material made of an iron-based material that is a conductive material.
[0030]
As shown in FIG. 3, the valve seat member 20 has an upper end surface 20a and an inner peripheral portion 20b which are non-joined end surfaces, and an outer peripheral portion where two tapered portions 20c and 20d are formed as joined end surfaces. In addition, the taper portion 20c is brought into contact with the opening edge 15b of the port portion 15a of the cylinder head 15 by pressing the electrode portion 19 in the coolant 33 in the water tank 14, and the heat generation is concentrated by energizing the cylinder head. The material is pushed in while plastically flowing.
[0031]
As shown in FIG. 2, the electrode portion 19 includes a cylindrical electrode tip holder 21 fixed to a lower portion of the platen 18 by bolts 21 a and the like, and an electrode fixed to a lower end portion of the electrode tip holder 21 by screwing with a convex portion. It includes a tip 22 and a cylindrical curtain member 23 provided so as to surround the outer peripheral surface of the electrode tip holder 21.
[0032]
The electrode tip holder 21 is made of a conductive material such as chromium copper, and the electrode tip 22 is also made of a conductive material such as chrome. The curtain member 23 forms a curtain passage 23a that opens downward between the curtain member 23 and the outer peripheral surface of the electrode tip holder 21.
[0033]
Inside the electrode tip holder 21, a coolant passage 24 for flowing coolant (factory water) introduced from the outside in the axial direction of the holder, and cooling from the outer peripheral surface of the electrode tip holder 21 to the coolant passage 24. An introduction passage 25 for introducing the liquid and a branch passage 26 branched from the coolant passage 24 and communicating with a curtain passage 23 a between the outer peripheral surface of the electrode tip holder 21 and the curtain member 23 are formed. .
[0034]
Further, inside the electrode tip 22, a passage 27 inside the chip is formed which communicates with the coolant passage 24 while being mounted on the electrode tip holder 21.
[0035]
A coolant of about 5 atm is introduced from the introduction passage 25 into the coolant passage 24 and the in-chip passage 27 to cool the electrode tip 22. The coolant flowing from the branch passage 26 into the curtain passage 23 a is uniformly ejected in a curtain shape to the outer peripheral portion of the electrode chip 22 and the vicinity of the joint interface on the non-joining end face side of the valve seat member 20, and is joined in the coolant 33. The burr B1 made of the brazing material and the cylinder head material discharged from the interface to the non-joining end face of the valve seat member 20 or the outer peripheral portion of the electrode tip 22 is removed by cooling and blowing off. Thereby, the adhesion of the burrs to the electrode portion can be suppressed, and the life of the electrode portion can be extended.
[0036]
The electrode tip 22 has a contact portion 28 that contacts an upper end surface 20a that is a non-joining end surface of the valve seat member 20, and a valve seat having the contact portion 28 in contact with the upper end surface 20a of the valve seat member 20. A protruding portion 29 that fits into the non-joining end surface side of the inner peripheral portion 20b of the member 20 without a gap, and that has a diameter reduced in a tapered shape toward the joining end surface side to form a gap with the inner peripheral portion 20b; Having.
[0037]
The projecting portion 29 positions the valve seat member 20 with respect to the electrode chip 22 by fitting without tightly into the non-joining end face side of the inner peripheral portion 20 b of the valve seat member 20. The protruding portion 29 is formed to have a protruding length that protrudes from the joint end surface of the valve seat member 20 opposite to the non-joint end surface when the contact portion 28 contacts the upper end surface 20a of the valve seat member 20. Then, as described later, the burr B2 which has been projected downward at the time of joining is dammed and flows into the gap between the inner peripheral portion 20b of the valve seat member 20 and the outer peripheral portion of the protruding portion 29. The portion 20b and the outer peripheral portion of the protruding portion 29 are brought into a fitted state.
[0038]
FIG. 4 is a diagram illustrating a joining process of the cylinder head and the valve seat member. FIG. 5 is a diagram showing pulse waveforms of pulse currents respectively supplied in the joining step (a) and the demagnetizing step (tempering processing) (b). FIG. 6A shows a quenched hardened layer of the valve seat member quenched by resistance heating in the joining step, and FIG. 6B shows a quenched hardened layer of the valve seat member tempered by the demagnetizing step. It is.
[0039]
In the joining step, first, the valve seat member 20 held by the electrode tip 22 of the electrode portion 19 is moved to the port opening edge 15b of the cylinder head 15, and the valve seat 20 previously coated with the brazing material is moved to the position shown in FIG. Abut as shown in a).
[0040]
Next, as shown in FIG. 4B, the valve seat member 20 is pressed against the port opening edge 15b by the contact portion 28 of the electrode tip 22, and at the same time, the current is applied. Since there is an electric resistance at the joint surface between the port opening edge 15b of the cylinder head 15 and the tapered portion 20c of the valve seat member 20, the joint surface is heated by the pressing by the electrode tip 22 and the (pulse) energization. You. By continuing the pressurization and the heating, the material of the port opening edge 15b of the cylinder head 15 plastically flows, so that the valve seat member 20 passes through the state of FIG. As shown in FIG. 3), it is buried in the port portion 15a of the cylinder head 15 and melt-bonded.
[0041]
In the bonding step, a bonding current of about 90 kA × 1 pulse (0.1 to 0.6 seconds) shown in FIG.
[0042]
After the completion of the joining step, a reheating of about 30 to 50 kA × 1 to 5 pulses (0.1 to 3.0 seconds) lower than the joining current shown in FIG. An electric current is applied in the negative direction, and the valve seat member 20 is reheated by the resistance heat, thereby tempering the hardened layer inside the valve seat member.
[0043]
By the tempering process, as shown in FIG. 6B, the quenched and hardened layer (FIG. 6A) of the valve seat member quenched in the joining step is tempered to suppress an increase in hardness.
[0044]
In the demagnetization step, a reheating current shown in FIG. 5B is applied in the negative direction to generate a magnetic field in a direction opposite to that at the time of joining, thereby relaxing the magnetic force of the magnetized valve seat member 20. .
[0045]
According to the above embodiment, the joining, tempering, and demagnetization of the valve seat member can be performed by the same device, and a decrease in productivity and an increase in capital investment can be avoided.
[0046]
In particular, in the joining in a cooling liquid in which the valve seat member is easily quenched as in the present embodiment, the improvement in workability by tempering becomes remarkable.
[0047]
The demagnetization treatment described in the above embodiment can be applied not only to electric resistance welding but also to spot welding and the like, and can also be applied to joining of a power train member in addition to a valve seat member.
[Brief description of the drawings]
FIG. 1A is a diagram illustrating an overall configuration of a metal member joining apparatus according to an embodiment of the present invention, and FIG. 1B is a diagram illustrating an electrical configuration of a metal member joining apparatus according to an embodiment of the present invention. is there.
FIG. 2 is a cross-sectional view illustrating a configuration of an electrode unit of the bonding device of FIG.
FIG. 3 is a sectional view showing a positional relationship between a valve seat member and a cylinder head joined by the joining device of FIG. 1;
FIG. 4 is a diagram illustrating a joining process of a cylinder head and a valve seat member.
FIG. 5 is a diagram showing pulse waveforms of pulse currents respectively applied in a joining step (a) and a demagnetizing step (b).
6A is a diagram showing a quenched hardened layer of a valve seat member quenched by resistance heat generation in a joining process, and FIG. 6B is a diagram showing a quenched hardened layer of a valve seat member tempered by a demagnetizing process. .
[Explanation of symbols]
12 Transformer 15 Cylinder head 18 Platen 19 Electrode part 20 Valve seat member 21 Electrode tip holder 22 Electrode tip 23 Curtain member 23a Curtain passage 24 Coolant passage 25 Introductory passage 26 Branch passage 28 Contact part 29 Projection part 33 Coolant 41 Power supply unit 42 power supply 43 first capacitor 44 second capacitor 45 switching control unit 46 operation units B1, B2

Claims (6)

A joining step of joining a first metal member having magnetism by generating heat with electric resistance by energization and pressing by the electrode portion to a second metal member having a lower melting point than the first metal member;
A method of joining metal members, comprising a demagnetization step of demagnetizing the first metal member after the joining. 2. The method according to claim 1, wherein the demagnetization step includes a tempering process in which a current value lower than a current value applied in the bonding step and a current in a reverse direction is applied to reheat the metal member. 3. The method according to claim 1, wherein the joining step is performed in a cooling liquid. The metal member according to any one of claims 1 to 3, wherein the first metal member is an iron-based valve seat member, and the second metal member is a cylinder head made of an aluminum alloy. Joining method. Joining means for joining a first metal member having magnetism by generating heat with electric resistance by energization and pressing by the electrode portion to a second metal member having a lower melting point than the first metal member;
And a demagnetizing means for demagnetizing the first metal member after the joining. The apparatus according to claim 5, wherein the demagnetizing unit performs tempering by reheating by applying a current in a direction opposite to that of the current supplied by the joining unit.

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