JP4621533B2 - Friction stir welding method and apparatus - Google Patents

Description

  The present invention relates to a friction stir welding method and apparatus for friction stir welding of workpiece meat.

  2. Description of the Related Art In recent years, friction stir welding is being adopted when joining abutting portions formed by bringing the end surfaces of workpieces into contact with each other in a linear manner, or when joining laminated workpieces in a dotted manner. Friction stir welding, for example, when compared with arc welding, can suppress the temperature rise of the workpiece, so there is almost no distortion of the workpiece after welding, and it is not necessary to generate an arc, and it is low cost. Since there is no formation of a weld bead, there are advantages such as good appearance. Further, compared to rivet joining, bolts / nuts and rivet fastening parts are not required, and the operation is simple.

  The friction stir welding apparatus is configured, for example, such that a friction stir welding tool and a support jig are installed on an arm portion of a robot so as to face each other, and further, a friction stir welding tool provided on the arm portion is used. An elevating mechanism that moves up and down, and a rotating mechanism that urges the friction stir welding tool to rotate are provided. The friction stir welding tool is urged to rotate at a high speed under the action of the rotating mechanism, and then descends under the action of the elevating mechanism. Finally, the probe of the friction stir welding tool is brought into sliding contact with the workpiece in contact with the support jig.

  Due to the frictional heat generated at this time, the flesh of the workpiece softens and plastically flows. In other words, the meat is friction stir.

  The friction stir welding tool has a rotating body having a diameter larger than that of the probe, and the probe is provided at the tip of the rotating body. When the workpiece meat is frictionally stirred, the entire probe and the tip of the rotating body are inserted into the workpiece.

  After the predetermined amount of the entire probe and the rotating body is inserted, if the friction stir welding tool is separated from the work under the action of the lifting mechanism, the friction stirring of the meat is finished, and the meat is cooled and hardened. As a result, the workpieces are joined.

  By the way, when the insertion amount of the probe and the rotating body is excessively small, the meat is not sufficiently frictionally stirred, so that the bonding strength is reduced. On the other hand, if the insertion amount is excessively large, the workpiece is pressed by the rotating body, and the thickness is reduced. That is, the thickness reduction is increased, and thus the bonding strength is decreased.

  As can be understood from this, in order to ensure the bonding strength in the friction stir welding, it is necessary to control the insertion amount of the probe and the rotating body within an appropriate range. From such a point of view, Patent Documents 1 and 2 disclose that the friction stir welding tool and the welding direction along the direction in which the butted portions of the workpieces extend, that is, in front of the displacement direction of the friction stir welding tool, It has been proposed to arrange a measuring means for measuring the distance to the workpiece surface. In this case, the friction stir welding tool is displaced in a direction away from or approaching the workpiece surface so that the distance to the workpiece surface is constant.

  In Patent Document 3, the amount of insertion of the welding tool into the workpiece is controlled by controlling the distance between the welding tool (friction stir welding tool) and the support tool (supporting jig) to be constant. It has been proposed.

JP-A-11-226758 Japanese Patent Laid-Open No. 2001-170782 JP 2004-136365 A

  In the techniques described in Patent Literatures 1 and 2, when the friction stir welding tool is displaced along the abutting portion, the amount of displacement of the friction stir welding tool at the next arrival position is controlled. Therefore, this technique cannot be employed in so-called spot joining, in which the stacked workpieces are joined in a dot shape.

  In the technique described in Patent Document 3, the amount of bending of the arm portion of the robot is converted into data, and the amount of bending is input to the control means in advance to control the amount of displacement of the friction stir welding tool. However, this amount of deflection changes due to external factors such as the temperature, and the flexibility of the arm portion increases due to changes over time of the arm portion. In addition, as the workpiece softens, the arm part may return from the bent position to the original position or halfway, but even if the bending is reduced in this way, the friction stir welding tool Since the amount of displacement is not changed, there is an aspect in which the distance between the joining tool and the support tool is not necessarily constant. Further, even if the displacement amount of the friction stir welding tool is changed in accordance with the deflection amount, it is necessary to acquire data one by one, which is complicated.

  The present invention has been made to solve the above-described problem, and can be employed in spot welding, and the friction stir welding method can easily make the amount of the friction stir welding tool inserted into the workpiece constant. And an apparatus for the same.

In order to achieve the above-mentioned object, the present invention is to stiffen the meat of a laminated part formed by laminating a plurality of members in a dotted manner with a friction stir welding tool, and then harden the meat. In the friction stir welding method for joining,
Setting a target value of the insertion amount of the friction stir welding tool with respect to the laminated portion in the control means;
By inserting the rotating tool for friction stir welding into the laminated part, the meat of the laminated part is frictionally stirred, and the measured value of the amount of insertion of the friction stir welding tool into the laminated part is measured. Measuring by means;
Have
The insertion amount of the friction stir welding tool is set by controlling the amount of displacement of the friction stir welding tool so that the measured value matches the target value by the control means.

  Thus, in the present invention, the insertion amount of the friction stir welding tool into the workpiece is actually measured by the insertion amount measuring means, and the actually measured value is compared with the target value set in advance in the control means. The friction stir welding tool is displaced until the target value becomes equal to the target value. Accordingly, when the robot arm is bent and the insertion amount changes, the change in the insertion amount is measured by the insertion amount measuring means, and the friction stir welding is performed so that the insertion amount becomes the target value according to the measured value. The tool is displaced. Therefore, the amount of insertion can be made constant.

  After all, according to the present invention, it is avoided that the amount of insertion becomes excessively large or small. For this reason, the joining strength of a junction part is securable.

  Moreover, in this invention, since the insertion amount of the tool for friction stir welding is measured immediately, even when performing spot welding, it can implement suitably.

  As a specific method for measuring the insertion amount, for example, a contact type sensor is used as the insertion amount measuring means, the contact type sensor is contracted according to the insertion amount, and the contraction amount at this time is used as the insertion amount. You only have to get it.

In addition, the present invention provides a friction stir welding apparatus for friction stir welding a laminated portion formed by laminating a plurality of members in a dot shape,
A friction stir welding tool that is displaced in a direction approaching or separating from the laminated portion; and
An insertion amount measuring means for measuring the amount of insertion of the friction stir welding tool into the stacked portion while being displaced in a direction approaching or separating from the stacked portion in synchronization with the friction stir welding tool;
Control means for controlling the amount of displacement of the friction stir welding tool;
Have
The control means controls the friction stir welding tool by controlling the amount of displacement of the friction stir welding tool so that the measured value of the insertion amount measured by the insertion amount measuring means matches the target value. The amount of insertion is set.

  By adopting such a configuration, it becomes easy to perform the friction stir welding with the above-described friction stir welding method, that is, the amount of insertion of the friction stir welding tool inserted into the workpiece constant.

  Note that the insertion amount measuring means is preferably a contact sensor that can contract according to the insertion amount. In this case, there is an advantage that the measurement error is small.

  According to the present invention, the insertion amount of the friction stir welding tool into the workpiece is actually measured by the insertion amount measuring means, and the actual measurement value is compared with the target value preset in the control means, The amount of displacement of the friction stir welding tool is controlled so that the values match. As a result, the amount of insertion is controlled to be substantially constant, so that sufficient bonding strength is ensured at the bonding portion.

  Furthermore, since the control is performed so that the measured value of the insertion amount matches the target value, even when the robot is provided with a friction stir welding apparatus, even if the arm portion of the robot is bent, the insertion amount is set to the target value. Can be matched.

  In addition, as a result of adopting such a control method, the actual measurement value of the insertion amount of the friction stir welding tool is immediately measured, so that spot welding can also be performed.

  Hereinafter, preferred embodiments of the friction stir welding method according to the present invention will be described in detail with reference to the accompanying drawings in connection with an apparatus for carrying out the method.

  FIG. 1 is an enlarged explanatory view of a main part of a friction stir welding apparatus 10 according to the present embodiment. The friction stir welding apparatus 10 is configured such that a friction stir welding tool 12 and a support jig 14 are installed on a substantially C-shaped arm portion (both not shown) of a robot so as to face each other. A lifting mechanism (not shown) that is provided on the arm portion and moves up and down the friction stir welding tool 12; a rotating mechanism (not shown) that urges the friction stir welding tool 12 to rotate; and a spindle 16 coupled to the rotating mechanism; It comprises. Among these, the spindle 16 is surrounded by the spindle cover 18.

  The friction stir welding tool 12 includes a probe 20 and a rotating body 22 having a cylindrical body having a diameter larger than that of the probe 20, and the probe 20 is provided so as to protrude from the distal end surface of the rotating body 22. At the same time, the other end of the rotating body 22 is connected to the spindle 16.

  The spindle cover 18 is tapered in diameter toward the front end portion close to the friction stir welding tool 12, and an annular flange portion 24 is provided on the front end surface. A disc-shaped member 30 is connected to the annular flange portion 24 via bolts 26 and nuts 28 arranged in an annular shape, and an arc-shaped flange member 32 is disposed below the disc-shaped member 30. ing. The arc-shaped flange member 32 is elastically biased downward in FIG. 1 by a coil spring 34 and is held by a guide pin 36.

  That is, a bolt hole 37 is formed through the disk-shaped member 30, and the head of the guide pin 36 abuts in the vicinity of the opening of the bolt hole 37 on the lower end surface of the disk-shaped member 30. A bolt 38 passed through the bolt hole 37 is screwed into the head. A washer 39 is interposed between the bolt 38 and the disk-shaped member 30.

  The arc-shaped flange member 32 is also provided with a through hole 40, and the body portion of the guide pin 36 is passed through the through hole 40. A stopper portion 41 wider than the through hole 40 is provided on the lower end surface of the guide pin 36, and the stopper portion 41 prevents the guide pin 36 from coming off from the through hole 40.

  On the other hand, an annular spring receiver 42 is joined to the upper end surface of the arc-shaped flange member 32 so as to surround the body portion of the guide pin 36. The coil spring 34 is interposed between the spring receiver 42 and the head of the guide pin 36. As described above, the arc-shaped flange member 32 is elastically biased downward by the coil spring 34 in FIG.

  A contact sensor 46 is further interposed between the arc-shaped flange member 32 and the disk-shaped member 30. The contact sensor 46 has a main body 48 that has a substantially convex cross-sectional shape and a protruding portion that extends in the horizontal direction, and a contact portion that protrudes from the main body 48 and can be expanded and contracted. 50. As will be described later, the backward movement amount (shrinkage amount) of the contact portion 50 is acquired as an actual measurement of the insertion amount of the friction stir welding tool 12.

  Further, a contact 54 having a protrusion 52 protruding toward the support jig 14 is connected to the lower end surface of the arc-shaped flange member 32 via a bolt 56 and a nut 58.

  In the above configuration, the contact sensor 46, the lifting mechanism, and the rotating mechanism are electrically connected to a control circuit (not shown).

  Next, in the friction stir welding method according to the present embodiment, the laminated part L formed by laminating the first work W1 and the second work W2 with each other by the friction stir welding apparatus 10 configured as described above is used. A case of spot bonding will be described as an example.

  As shown in FIG. 2 which is a flowchart, first, in step S1, a target value for the amount of insertion of the friction stir welding tool 12 into the layered portion L is set. For example, the thickness of both the first workpiece W1 and the second workpiece W2 is 2 mm, the length of the probe 20 is 3.5 mm, and the total of the probe 20 and the tip end portion 0.2 mm of the rotating body 22 is 3 in total. When .7 mm is inserted, the target distance is set by adding the separation distance between the front end surface of the rotating body 22 and the upper end surface of the second workpiece W2 to 3.7 mm. In the present embodiment, the height at which the tip surface of the rotating body 22 and the tip of the protrusion 52 of the contactor 54 coincide with each other is defined as a zero point.

  On the other hand, the second workpiece W2 is stacked on the first workpiece W1 to form a stacked portion L (see FIG. 1). The laminated portion L is positioned at a predetermined location of a station that performs spot bonding.

  When the stacking portion L is positioned, the friction stir welding tool 12 and the support jig 14 disposed on the arm portion of the robot are then stacked under the action of the robot as shown in FIG. It moves to a position that sandwiches the part L. Finally, the lower end surface of the first workpiece W1 comes into contact with the upper end surface of the support jig 14.

  Next, the friction stir welding tool 12 is urged to rotate under the action of the rotating mechanism, and in this state, the friction stir welding tool 12 is lowered under the action of the lifting mechanism and approaches the laminated portion L (see FIG. 2 step S2). At this time, the spindle cover 18 descends in synchronization with the friction stir welding tool 12, and the arcuate flange member 32 and thus the contact sensor 46 descends following this. As a result, as shown in FIG. 3, the tip of the protrusion 52 of the contactor 54 comes into contact with the stacked portion L.

  When the friction stir welding tool 12 and the spindle cover 18 are further lowered, the tip of the projection 52 receives a reaction force from the laminated portion L, and the arcuate flange member 32 is relatively raised along the guide pin 36. At the same time, the contact portion 50 of the contact sensor 46 moves backward to enter the main body 48. At this time, the coil spring 34 contracts, while the upper end surface of the stopper portion 41 is separated from the lower end surface of the arcuate flange member 32.

  The backward movement amount (shrinkage amount) of the contact portion 50 is transmitted as a signal to the control circuit. At this time, since the tip of the protrusion 52 of the contactor 54 is in contact with the upper end surface of the second workpiece W2 and the tip of the rotating body 22 is located higher than the tip of the protrusion 52, the control circuit Then, a control signal “Further lowering the friction stir welding tool 12” is issued to the lifting mechanism.

  The lifting mechanism that has received this control signal operates to further lower the friction stir welding tool 12. As a result, the spindle cover 18 is further lowered while being guided by the guide pins 36 in synchronization with the friction stir welding tool 12, and the contact portion 50 of the contact sensor 46 is further moved backward. Moreover, the vicinity of the location where the friction stir welding is performed is pressed by the protrusion 52, and the first workpiece W1 and the second workpiece W2 are brought into close contact with each other.

  Finally, the probe 20 comes into sliding contact with the upper end surface of the second workpiece W2, and frictional heat is generated along with this sliding contact. As a result, the upper end surface of the second workpiece W2 and the vicinity thereof are softened, and the probe 20 is inserted into the second workpiece W2 as shown in FIG.

  In the middle of this, the tip surface of the rotating body 22 is flush with the tip of the protrusion 52 of the contactor 54. The control circuit sets this point as the zero point, and the subsequent retraction amount (shrinkage amount) of the contact portion 50 of the contact sensor 46 as an actual measurement value of the insertion amount of the probe 20 and the rotating body 22 into the laminated portion L. recognize. In other words, the contraction amount of the contact portion 50 after the zero point is acquired as an actual measurement value of the insertion amount of the probe 20 and the rotating body 22 into the stacked portion L.

  The control circuit constantly compares the actual measurement value with a preset target value (step S3 in FIG. 2), and if the actual measurement value does not satisfy the target value, the control circuit 12 sends a “friction stir welding tool 12”. The control signal is issued.

  Upon receiving this control signal, the lifting mechanism operates to further lower the friction stir welding tool 12 (step S2). This descent is performed until the target value matches the actual measurement value.

  While the friction stir welding tool 12 is being lowered, the friction stir welding tool 12 continues to rotate, so that the meat of the second workpiece W2 is constantly friction stir. After the probe 20 reaches the first workpiece W1, plastic flow occurs so that the meat of the second workpiece W2 and the meat of the first workpiece W1 are mixed together.

  When the target value matches the actual measurement value, that is, in the case of the present embodiment, as shown in FIG. 5, when the entire probe 20 is inserted and the tip portion 0.2 mm of the rotating body 22 is inserted, the control is performed. The circuit transmits a control signal “stop descent operation” to the elevating mechanism (step S4). As a result, the lowering of the friction stir welding tool 12 is completed and the positioning is maintained.

  When the friction stir welding tool 12 is inserted into the laminated portion L with a predetermined insertion amount and rotates, the meat of the first workpiece W1 and the second workpiece W2 is reliably frictionally stirred by the probe 20 and mixed. . Moreover, the thickness reduction does not become excessively large. Therefore, the laminated portion L can be bonded with excellent bonding strength.

  Moreover, according to the present embodiment, the amount of contraction from the zero point of the contact portion 50 in the contact sensor 46 is acquired as an actual measured value of the amount of insertion of the friction stir welding tool 12 into the laminated portion L, and this measured value and The amount of displacement of the friction stir welding tool 12 is controlled such that the actual value matches the target value by comparing the target value preset in the control circuit. In such a control method, the amount of insertion of the friction stir welding tool 12 is constant even when the amount of bending of the arm portion of the robot changes due to external factors or changes over time. Therefore, the bonding strength after spot bonding can be secured without being affected by the amount of bending of the arm portion. In addition, in this case, it is not necessary to acquire data of an appropriate amount of displacement of the friction stir welding tool 12 according to the amount of bending of the arm portion.

  After the predetermined time has elapsed, the control circuit sends a control signal “raises the friction stir welding tool 12” to the lifting mechanism (step S5). Upon receiving this control signal, the lifting mechanism raises the friction stir welding tool 12 as shown in FIG. When the spindle cover 18 rises following this, the friction stir welding tool 12 is detached from the laminated portion L, and the tip of the protrusion 52 of the contactor 54 is separated from the upper end surface of the second workpiece W2. Further, the arc-shaped flange member 32 is elastically biased by the coil spring 34 and is displaced downward until it comes into contact with the damming portion of the stopper member. Further, the rotating operation of the raised friction stir welding tool 12 is stopped.

  As the friction stir welding tool 12 is disengaged, the plastic flow of the meat in the laminated portion L, that is, the friction stirrer is finished, and the meat is cooled and hardened. As a result, the first workpiece W1 and the second workpiece W2 are integrally spot-bonded with good bonding strength. Note that a separation hole H is formed at the spot-bonded portion.

  When spot joining is performed on a laminated portion L in which workpieces having different thicknesses from the first workpiece W1 and the second workpiece W2 are laminated, a target value set in the control circuit according to the thickness of the workpiece Can be changed. Thus, according to this Embodiment, the insertion amount of the tool 12 for friction stir welding can be changed easily and simply.

  After repeating the above operation, the zero point of the position of the tip surface of the rotating body 22 is corrected as necessary. That is, while the entire probe 20 can be inserted, a correction plate provided with a recess having a dimension in which the rotating body 22 cannot be inserted is prepared, and the probe 20 is inserted into the recess of the correction plate, The front end surface of the rotating body 22 and the front end of the protrusion 52 of the contactor 54 are brought into contact with the upper end surface of the correction plate. Thereby, the front end surface of the rotating body 22 and the front end of the protrusion 52 of the contactor 54 can be accurately matched, and a zero point can be set.

  By performing the zero point correction in this way, it becomes possible to accurately measure the actual measurement value of the amount of burying of the probe 20. Accordingly, the size of the friction stir welding tool 12 changes when the friction stir welding tool 12 is worn due to repeated work, or when the friction stir welding tool 12 undergoes thermal expansion due to frictional heat generated during the work. Even if it does, the exact measured value of the amount of burying of the probe 20 can be obtained.

  In the above-described embodiment, the contact type sensor 46 is exemplified and described as the insertion amount measuring means for measuring the insertion amount of the friction stir welding tool 12 into the layered portion L. For example, a non-contact sensor may be used. As this type of non-contact type sensor, for example, there is a sensor that irradiates a laser beam and calculates a distance from a time until the laser beam returns by reflection.

  Further, according to the friction stir welding apparatus 10 according to the present invention, the thickness of the workpiece can be measured in advance before performing the friction stir welding. That is, the initial distance between the tip of the protrusion 52 of the contact 54 that has risen to the highest position and the upper end surface of the support jig 14 is obtained in advance. Next, the work is placed on the support jig 14, and the spindle cover 18 and thus the contact 54 are lowered under the action of the lifting mechanism.

  The tip of the protrusion 52 of the lowered contactor 54 finally comes into contact with the upper end surface of the workpiece. The thickness of the workpiece is calculated by subtracting the movement distance of the protrusion 52 at that time from the initial distance. At this time, only the pressing force with which the contact 54 abuts against the work acts, so the arm portion does not bend. Therefore, there is no measurement error in the workpiece thickness due to the bending of the arm portion. In addition, the movement distance of the projection part 52 can be calculated | required based on the movement distance of a raising / lowering mechanism.

  If the target value set in the control circuit is changed in accordance with the thickness of the workpiece thus measured, even if the workpiece thickness varies, the amount of displacement of the friction stir welding tool 12 Is appropriately set for each workpiece, whereby a joint with excellent joint strength can be obtained.

  Further, if it is found from this measurement that the thickness of the workpiece is outside the allowable range, the friction stir welding may not be performed. In this way, by measuring the thickness of the workpiece in advance, it is possible to remove a workpiece that is difficult to perform friction stir welding. For this reason, work efficiency improves and manufacturing yield also improves.

  In either case, an annular flange member may be attached instead of the arc-shaped flange member 32. In this case, an annular contact may be used in place of the contact 54, and the protrusion may project in an annular shape from the annular contact toward the stacking portion L. When the laminated portion L is inclined, the portion closest to the annular protrusion in the laminated portion L is pressed by the annular protrusion, and as a result, this portion is inclined toward the support jig 14 side. As a result, the inclined state of the laminated portion L is eliminated, and the probe 20 is inserted substantially perpendicular to the laminated portion L. Therefore, the laminated portion L can be more reliably joined.

It is principal part expansion explanatory drawing of the friction stir welding apparatus which concerns on this Embodiment. It is a flowchart which shows the friction stir welding method which concerns on this Embodiment. It is a principal part expansion explanatory drawing which shows the state which the tool for friction stir welding descend | falls and the front-end | tip of the protrusion part of a contact contact | abutted on the lamination | stacking site | part. It is principal part expansion explanatory drawing which shows the state which the tool for friction stir welding further falls, and the probe was inserted in the upper end surface of a 2nd workpiece | work. It is a principal part expansion explanatory drawing which shows the state which the tool for friction stir welding fell further further, and the rotary body was inserted to the predetermined position of the lamination | stacking site | part. It is a principal part expansion explanatory drawing which shows the state which the tool for friction stir welding went up and removed | separated from the lamination | stacking site | part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Friction stir welding apparatus 12 ... Friction stir welding tool 14 ... Support jig 16 ... Spindle 18 ... Spindle cover 20 ... Probe 22 ... Rotating body 24 ... Annular flange part 30 ... Disc-shaped member 32 ... Arc-shaped flange member 34 ... Coil spring 36 ... guide pin 46 ... contact type sensor 50 ... contact part 52 ... projection part 54 ... contacts W1, W2 ... workpiece L ... lamination part

Claims (2)

Friction stir welding in which the meat of the laminated part formed by laminating a plurality of members is frictionally stirred in a dotted manner with a friction stir welding tool having a probe and a rotating body, and then the meat is cured and joined. In the method
Setting a target value of the insertion amount of the friction stir welding tool with respect to the laminated portion in the control means;
By inserting the rotating tool for friction stir welding into the laminated part, the meat of the laminated part is frictionally stirred, and the measured value of the amount of insertion of the friction stir welding tool into the laminated part is measured. Measuring by means;
Have
As the insertion amount measuring means, a contact type sensor having a contact is used, and the contact sensor in which the contact is in contact with the laminated portion is contracted in accordance with the insertion amount to constitute the friction stir welding tool When the tip of the rotating body to be the same height as the tip of the contact is zero, the subsequent contraction amount is acquired as the measured value of the insertion amount,
Friction stirrer, characterized in that the amount of friction stir welding tool insertion is set by controlling the amount of displacement of the friction stir welding tool so that the measured value matches the target value by the control means. Joining method. In a friction stir welding apparatus for performing friction stir welding of a laminated portion formed by laminating a plurality of members in a dot shape,
A friction stir welding tool that has a probe and a rotating body and is displaced in a direction approaching or separating from the laminated portion;
An insertion amount measuring means for measuring the amount of insertion of the friction stir welding tool into the stacked portion while being displaced in a direction approaching or separating from the stacked portion in synchronization with the friction stir welding tool;
Control means for controlling the amount of displacement of the friction stir welding tool;
Have
The insertion amount measuring means comprises a contact sensor that has a contact and can contract according to the insertion amount,
The control means is configured such that when the contact sensor in contact with the stacked portion contracts , the tip of the rotating body constituting the friction stir welding tool becomes the same height as the tip of the contact. The amount of contraction of the contact-type sensor thereafter is determined as the measured value of the insertion amount, and the displacement amount of the friction stir welding tool is controlled so that the measured value of the insertion amount matches the target value. By doing so, the amount of insertion of the tool for friction stir welding is set.

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