JP5381766B2 - Welding method - Google Patents

Description

  The present invention relates to a method for welding cylindrical members.

  2. Description of the Related Art In various fields, two cylindrical members are fitted, that is, they are combined coaxially and then joined by fusion welding in the circumferential direction. During the welding, it is usually required to suppress as much as possible the deterioration of the coaxiality between the two members based on the welding deformation or the increase in circumferential runout.

  For example, in the welding method described in Patent Document 1, two laser irradiation heads are used for the purpose of suppressing welding deformation in two cylindrical members and correcting deformation generated in the press-fitting locations of those members before welding. It has been proposed to arrange them 90 degrees apart in the circumferential direction.

JP 2002-321077 A

  By the way, a "clearance fit" that allows clearance between the fitting portions of two cylindrical members is often employed to reduce the member cost or assembly cost. In such a case, due to the clearance, The two cylindrical members may already have eccentric or tilted axes before welding. Therefore, there is a problem that such eccentricity or inclination is enlarged by welding deformation, and the error of circumferential runout of the member after welding is remarkably increased. Further, this problem cannot be solved by the welding method described in the cited document 1 which does not consider the clearance as a condition.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a welding method with less occurrence of circumferential run-out error in welding of a cylindrical member having a clearance at a fitting portion. is there.

In order to solve the above-mentioned problem, the invention described in claim 1 includes a cylindrical first member (21) and a cylindrical second member (22) fitted into the first member (21). In this welding method, a workpiece (W) is welded using a laser welding machine, and the first member (21) can be gripped and rotated about the longitudinal axis (Ar) of the first member (21) as a rotation center. A step of fixing the first member (21) to the work gripping rotation device, a step of inserting and inserting the second member (22) into the first member (21), and a second having a maximum radius (Rmax) from the rotation center. Measuring the first angular position (θ ₁ ) of the workpiece (W) representing the angular position of the maximum radius point (K ₁ ), which is a point on the outer periphery of the member (22), and the first angular position (θ ₁ ) the second angular position (theta ₂₎ of the first angular position is the angular position of the diametrically opposite side of the workpiece (W) (θ ₁₎ And the step of laser welding the first member (21) and the second member (22) in the circumferential direction while rotating the workpiece gripping and rotating device, and the second angular position of the workpiece (W) Laser welding, controlling the rotation of the workpiece gripping rotation device and the laser welding machine so that melting of the interface between the first member (21) and the second member (22) starts at (θ ₂ ); viewed contains a step of removing the W) from the work grip and rotation device, a third angular position obtained by correcting the second angular position correction angle (alpha) the step of calculating the (theta _3), the second angular position (theta ₂ ) Is calculated from the first angular position (θ ₁ ), and the correction angle (α) is determined in advance in consideration of the time from the start of the workpiece gripping rotation device to the stabilization of the angular velocity. At a specified angle and during laser welding, the workpiece Provided is a welding method in which the third angular position (θ ₃ ) of (W) is arranged opposite to the welding head (23) of a laser welding machine and then the workpiece gripping rotation device is rotated and started .

  Thus, by controlling the melting at the interface between the first and second members to start at the second angular position opposite to the direction of inclination or eccentricity before welding, the inclination or eccentricity before welding is welded. It was found that it was corrected later, and thus it was confirmed that it was effective for welding a cylindrical member having a clearance at the fitting portion. Moreover, the reason why the inclination or eccentricity before welding is corrected is considered to be that the joining force acts at the start of melting and the second member is drawn in the welding start direction (second angular position side).

Furthermore, according to this, since the interface starts melting after the rotation of the workpiece gripping and rotating device is stabilized, the uniformity of welding is ensured.

In the invention described in claim 2 , the step of measuring the first angular position (θ ₁ ) includes the step of rotating the workpiece (W) in one direction using the workpiece gripping rotation device, and the maximum radius point (K ₁ ). and determining a rotational movement amount of the maximum radius point (K ₁₎ and a work when the generated (W) (Tmax) detects a, on the basis of the rotational movement amount (Tmax), the maximum radius point of (K ₁₎ It includes a step of obtaining the first angular position (θ ₁ ) and a step of stopping the rotation of the workpiece (W).

According to a third aspect of the present invention, in the step of measuring the first angular position (θ ₁ ), a projector that irradiates the band-shaped light beam toward the measurement target portion of the second member (22) of the workpiece (W). (25) and a light receiver (26) having a light receivable width substantially equal to the width of the measurement target portion of the second member (22), and disposed opposite the projector (25) with the second member (22) interposed therebetween. An area sensor (24) including the received light receiver (26) is used. According to this, it is possible to construct a measurement system for the first angular position using a relatively simple and standard area sensor.

  In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

It is a longitudinal cross-sectional view of the fuel injection valve which can apply the welding method by this invention. It is a typical front view of the workpiece | work which applies the welding method of 1st Embodiment by this invention. It is a figure which shows typically the relationship between the area sensor used with the welding method of 1st Embodiment, a workpiece | work, and a welding head. It is a figure which shows typically the relationship between the area sensor used with the welding method of 1st Embodiment, a workpiece | work, and a welding head. It is a figure which shows each angular position etc. of the workpiece | work in the welding method of 2nd Embodiment. It is a flowchart of the welding method by 1st Embodiment. It is a flowchart of the welding method by 2nd Embodiment.

  The welding method according to the present embodiment relates to a laser welding method for two cylindrical members, and the two cylindrical members may be used for various applications. A description will be given of an example in which a constituent member of a fuel injection valve that injects and supplies fuel to an internal combustion engine is a workpiece.

First, the constituent members of the fuel injection valve will be briefly described.
A fuel injection valve 1 shown in FIG. 1 includes a stepped cylindrical main pipe portion 2, an inner connector portion 3 disposed on the inner side of the main pipe portion 2, and an axial direction on the distal end side of the inner connector portion 3. And a movable core 4 attracted to the inner connector portion 3 by a magnetic attractive force generated between the inner connector portion 3 and the jet that moves in the axial direction together with the movable core 4 and injects fuel. A needle 6 serving as a valve member for opening and closing the hole 5 and an outer connector portion 7 for introducing fuel into the main pipe portion 2 from the outside are provided. The outer connector portion 7 is also formed in a stepped cylindrical shape, and has an upper small diameter portion 7a and a lower large diameter portion 7b in the figure, and further closer to the lower end of the large diameter portion 7b. It has a large-diameter annular protrusion 7c. The large-diameter portion 7b below the annular projecting portion 7c is referred to as an outer connector joint portion 7d. The components are arranged coaxially with a common longitudinal axis Ax.

  Further, a coil 8 that generates a magnetic field when energized and a terminal 9 for supplying current to the coil 8 are disposed on the outer peripheral side of the main pipe portion 2. A coil housing 10 for covering and holding the coil 8 is provided.

  When the fuel injection valve 1 is assembled, the main pipe portion 2 has the needle 6, the movable core 4, the inner connector portion 3 and the like housed therein, and the coil housing 10 housing the coil 8 is fixed by welding or the like. After the main housing 11 is formed, the outer connector joint 7d is finally fixed by welding on the upper end side.

  The joint 11a (hereinafter referred to as “main housing joint 11a”) and the outer connector joint 7d in the vicinity of the upper end of the main housing 11 are of course formed in a cylindrical shape, and the outer connector joint is formed inside the main housing joint 11a. 7d is fitted and inserted, and the upper end surface of the main housing 11 comes into contact with the annular projecting portion 7c of the outer connector portion 7, whereby the two members are positioned in the vertical direction. However, a “clearance fit” is employed for fitting the main housing joint portion 11a and the outer connector joint portion 7d, so that a clearance is generated between the two joint portions. Further, the welding is performed by continuous laser welding at the portion indicated by the arrow A in FIG.

(First embodiment)
Next, with reference to FIGS. 2-5, the welding method by the 1st Embodiment of this invention, the apparatus used for the method, etc. are demonstrated. FIG. 2 is a schematic front view showing a fuel injection valve and a welding head 23 of a laser welder (not shown), but the fuel injection valve is simplified and constructed from that of FIG. A portion indicated by reference numeral 21 corresponds to the main housing 11 of FIG. 1, and a portion indicated by reference numeral 22 corresponds to the outer connector portion 7 of FIG. In the following description, the main housing is referred to as a “first member”, and the outer connector portion is referred to as a “second member”. Accordingly, the workpiece W is constituted by the first member 21 and the second member 22.

  In the method according to the first embodiment of the present invention, first, the first member 21 is first gripped and fixed to a general three-claw type workpiece gripping and rotating device (not shown). This workpiece gripping and rotating device is rotationally driven around a rotation axis Ar that coincides with the Z axis in FIG. 2 by a step motor (not shown). Further, the workpiece gripping rotation device (not shown) can grip the outer peripheral portion of the first member 21 so that the rotation axis Ar thereof coincides with the axis of the first member 21. Further, a welding head 23 of a laser welding machine (not shown) is fixed so as to irradiate the outer peripheral surface of the first member joint near the upper end of the first member 21 with laser light.

  In the next stage, the second member 22 is inserted into the upper end side of the first member 21. At that time, the second member 22 may be inclined by an angle δ with respect to the first member 21 due to the shape error or the clearance of the fitting portion. In FIG. 2, the angle δ is exaggerated for easy understanding. Although not shown, the second member 22 may be arranged eccentrically with respect to the first member 21 due to the clearance although there is no such inclination of the angle δ.

When the workpiece W is rotated about the Z axis when the second member 22 is tilted or eccentric with respect to the first member 21 as described above, circumferential runout based on the tilt and / or eccentricity occurs. For this reason, in the method according to the first embodiment, the direction in which the inclination and / or eccentricity of the second member 22 occurs next is examined. In other words, the point K ₁ having the maximum radius Rmax from the Z axis is detected among the points on the outer peripheral surface of the second member 22 on the predetermined measurement plane orthogonal to the Z axis. Therefore, a method for detecting a point K ₁ having the maximum radius Rmax (hereinafter referred to as “maximum radius point”) will be described with reference to FIGS. 3 and 4 show the X and Y axes orthogonal to each other, the Z axis that is the rotation axis Ar, and the outer peripheral contour of the cross section in the vicinity of the upper end portion of the second member 22 that is inserted into the first member 21. The welding head 23 arrange | positioned on the X-axis and the optical area sensor 24 mentioned later are shown typically.

The maximum radius point K ₁ can be detected using, for example, a dial gauge or the like (not shown), but in this embodiment, it is detected using the optical area sensor 24 because of its suitability for automation. Is done. Therefore, the area sensor 24 used in the present embodiment will be described below. The area sensor 24 is schematically shown as a plurality of arrow lines in FIGS. 3 and 4, but a projector 25 that emits one continuous belt-like laser beam, and a light receiver that receives the belt-like laser beam. 26, the light projector 25 and the light receiver 26 are arranged to face each other with the second member 22 as a measurement symmetrical portion of the workpiece W interposed therebetween as shown in FIG. In this embodiment, the width W _L of the belt-shaped laser beam and the width W _R of the light receiving region of the light receiving element 27 of the light receiver 26 are substantially equal to the outer diameter of the measurement portion of the second member 22. The light receiving element 27 is one that can be measured and the amount of light received for each site is subdivided in the direction of the width W _L of the beam, both total amount of light received by the light receiving element 27 as a total.

Next, how the maximum radius point K ₁ is detected using the area sensor 24 will be described. FIG. 3 shows an initial state before the rotation of the workpiece W. The workpiece W has a workpiece reference point K ₀ at a position of 0 degrees in the circular coordinates, and is counterclockwise from the workpiece reference point K _0. And has a maximum radius point K ₁ having a maximum radius Rmax at an angular position of θ ₁ degree. In this initial state, the beam in the region on the right side of the center of the belt-shaped laser beam emitted from the projector 25 is completely blocked by the second member 22, and only the beam in the slight leftmost region reaches the light receiving element 27. I understand that. In the present specification, the angular position of the maximum radius point K ₁ with respect to the workpiece reference point K ₀ is referred to as a first angular position θ ₁ .

Then, the first angular position θ ₁ is measured while the workpiece W in the initial state is rotated at least once counterclockwise around the Z axis using the workpiece gripping and rotating device. When the workpiece W starts to rotate, the amount of light received by the light receiver 26 changes with the amount of rotational movement T. For example, when the rotational movement amount T is, for example, (90−θ ₁ ) degrees (not shown), that is, when the maximum radius point K ₁ coincides with the Y axis, the belt-like laser beam is blocked by the second member 22 of the workpiece W. As a result, the minimum amount of received light is measured. On the other hand, when the rotational movement amount T is (180−θ ₁ ) degrees, for example, the maximum radius point K ₁ is on the X axis (180 degrees (FIG. 4) or 0 degrees (not shown) of the circular coordinates). the beam width W _L of the right end side of the strip the laser beam reaching the light receiving element 27 when matched (Fig. 4) or left side (not shown) is maximized, the amount of light received as a result the maximum level is measured.

Therefore, the angular position of the maximum radius point K ₁ , that is, the first angular position θ ₁ can be obtained based on the rotational movement amount Tmax of the workpiece W when the maximum value of the received light amount occurs. Specifically, if the light receiving amount of the light receiving element 27 in the region on the right side of the Y axis when the maximum value of the light receiving amount is large (FIG. 4), the first angular position θ _{1 with} respect to the workpiece reference point K ₀ is It is obtained by the following equation (1).
θ ₁ = (180−Tmax) ° (1)
On the other hand, if the amount of light received by the light receiving element 27 in the region on the left side of the Y axis when the maximum value of the amount of received light is large (not shown), the first angular position θ ₁ is (2) It is calculated by the formula.
θ ₁ = (360−Tmax) ° (2)
For example, if the rotational movement amount Tmax when the maximum value of the received light amount occurs is 100 degrees and the received light amount of the light receiving element 27 in the region on the right side of the Y-axis is large, the second reference point regarding the workpiece reference point K _{0 is obtained} . One angular position θ ₁ is found to be 80 degrees from the equation (1).

Then the welding method of this embodiment, by plus first angular position theta ₁ 180 degrees measured, the second angle representing the angular position of the diametrically opposite point K ₂ located on the opposite side of the maximum radius point K ₁ The position θ ₂ is calculated. For example, if the measured value of the first angular position θ ₁ is 80 degrees, the second angular position θ ₂ is calculated as 260 degrees.

  In the welding method of the present embodiment, the workpiece gripping and rotating device is temporarily stopped after at least one rotation.

Next, the workpiece W is continuously welded by irradiating a laser beam from the welding head 23 while starting to rotate the workpiece gripping rotation device counterclockwise and rotating it once. However, at this time, the rotation timing of the workpiece gripping rotation device and the irradiation timing of the laser beam are controlled so that the interface between the first member 21 and the second member 22 starts to melt at the second angular position θ ₂ . Note that the timing of laser beam irradiation is controlled specifically by considering the time lag between turning on the laser irradiation switch of the laser welding machine and starting melting of the interface. It is that it is thrown in.

  Next, the workpiece W is removed from the workpiece gripping rotation device. Thus, the welding for one workpiece W is completed. Moreover, the flow of the welding method by 1st Embodiment is shown in FIG.

As described above, the workpiece gripping rotation device and laser welding are performed so that the melting at the interface between the first member 21 and the second member 22 starts at the second angular position θ ₂ opposite to the direction of inclination or eccentricity before welding. It has been found that by controlling the machine, tilt or eccentricity before welding is corrected after welding. This is considered because the joining force works at the start of melting and the second member 22 is drawn in the welding start direction (second angular position side).

In this embodiment the way, by using the area sensor 24, but measures the angular position of the maximum radius point K ₁ is a direction that is occurring inclination or eccentricity, such area sensor 24, the inclination or the eccentricity In other words, for example, the step of removing the workpiece W having a measured maximum radius Rmax exceeding a predetermined reference value as a defective product can be measured as the magnitude of the received light amount. Can also be added.

(Second Embodiment)
Since the method according to the second embodiment is almost the same as the method according to the first embodiment as shown in the flow chart of FIG. 7, only different parts will be described below.
The rotational movement of the workpiece gripping and rotating device includes an angular velocity increasing section immediately after the start and a constant angular velocity section following the angular velocity increasing section. In order to ensure the performance, welding is controlled so as to avoid melting of the interface after avoiding the angular velocity increasing section, that is, after the angular velocity of rotation of the workpiece W is stabilized.

For this reason, the method according to the second embodiment calculates the second angular position θ ₂ in the same manner as in the first embodiment, and then corrects the second angular position θ ₂ by adding a predetermined correction angle α. Calculating a third angular position θ ₃ representing the point K ₃ . The correction angle α is an angle determined in consideration of the time required for the workpiece gripping and rotating device to reach a stable angular velocity, and is 40 degrees in the present embodiment. Accordingly, the third angular position θ ₃ is set to 300 degrees.

Further, in the second embodiment, when the rotation of the work gripping rotation device is temporarily stopped after the work gripping rotation device is rotated at least once to obtain the first angular position θ ₁ or the like, the work W is moved to the third position. The angular position θ ₃ is located at 0 degrees of the circular coordinate and is stopped facing the welding head 23. FIG. 5 shows this state of the workpiece W.

Next, the laser beam is irradiated from the welding head 23 while the work gripping rotation device is started to rotate counterclockwise from the state where the third angular position θ ₃ is stopped facing the welding head 23 and rotated once. Then, continuous circumferential welding of the workpiece W is performed.

In the method according to the second embodiment, the third angular position θ ₃ is calculated by adding the correction angle α to the second angular position θ _2. However, the third angular position θ ₃ is corrected from the second angular position θ _2. It may be calculated by subtracting the angle α. However, in that case, the work gripping and rotating device in the welding stage must be started to rotate in the clockwise direction, not in the counterclockwise direction.

(Other embodiments)
In the above-described embodiment, after measuring the angular position of the maximum radius point K ₁ , the rotation of the workpiece gripping rotation device is temporarily stopped. However, this stop is not essential in the present invention, and the rotation is continued while continuing the rotation. It will be appreciated that the workpiece gripping rotation device and the welder may be controlled to transition to

21 First member 22 Second member 23 Welding head 24 Area sensor 25 Projector 26 Light receiver 27 Light receiving element K ₀ Reference point K ₁ Maximum radius point K ₂ Opposite point K ₃ Correction point θ ₁ First angle position θ ₂ Second angle Position θ ₃ Third angle position W Workpiece

Claims (4)

A welding method for welding a workpiece (W) comprising a cylindrical first member (21) and a cylindrical second member (22) inserted into the first member (21) using a laser welding machine. Because
Fixing the first member (21) to a work gripping and rotating device capable of gripping the first member (21) and rotating it about the longitudinal axis (Ar) of the first member (21); ,
Inserting the second member (22) into the first member (21);
The first angular position (θ ₁ ) of the workpiece (W) representing the angular position of the maximum radius point (K ₁ ) that is a point on the outer periphery of the second member (22) having the maximum radius (Rmax) from the rotation center. )
A step of calculating the second angle position (theta ₂₎ of the first angular position is the angular position of the diametrically opposite side of the workpiece (W) (θ ₁₎ of said first angular position (theta _1),
The step of laser welding the first member (21) and the second member (22) in the circumferential direction while rotating the workpiece gripping and rotating device, wherein the second angular position (θ) of the workpiece (W) for controlling said first member (21) and the rotation and the laser welding machine of the workpiece holding rotary device so that melting of the interface starts with the second member (22) in _2), the steps of laser welding,
A step of removing the workpiece (W) is from said workpiece holding rotary device, only including,
Calculating a second angular position the step of calculating a third angular position corrected by the correction angle (α) (θ _3), from the second angular position (theta ₂₎ of the first angular position (theta ₁₎ Further comprising following said step;
The correction angle (α) is a predetermined angle in consideration of the time from the start of the workpiece gripping rotation device until the angular velocity is stabilized,
In the step of laser welding, the workpiece gripping rotation device is started to rotate after the third angular position (θ ₃ ) of the workpiece (W) is disposed opposite the welding head (23) of the laser welding machine. Welding method. Measuring the first angular position (θ ₁ ) comprises:
Rotating the workpiece (W) in one direction using the workpiece gripping rotation device;
A step of determining the rotational movement amount of the maximum radius point (K ₁₎ and a work when the generated (W) and (Tmax) with said detecting the maximum radius point (K _1),
Obtaining the first angular position (θ ₁ ) of the maximum radius point (K ₁ ) based on the rotational movement amount (Tmax);
The welding method according to claim 1, further comprising a step of stopping the rotation of the workpiece (W). In the step of measuring the first angular position (θ ₁ ), a projector (25) that irradiates a measurement target region of the second member (22) of the work (W) with a band-shaped light beam; A light receiver (26) having a light receivable width substantially equal to the width of the measurement target portion of the two members (22) and disposed opposite to the light projector (25) with the second member (22) interposed therebetween. A welding method according to claim 1 or 2 , characterized in that an area sensor (24) comprising (26) is used. Wherein said first member (21) second member (22), characterized in that a component of the injection for supplying the fuel injection valves of fuel to an internal combustion engine, to any one of claims 1 to 3 The welding method described.

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