JP6452390B2 - Friction stir spot welding device - Google Patents

Description

  The present invention relates to a friction stir spot welding apparatus that spot welds stacked metal plates together by friction stirring.

  Conventionally, point joining by friction stirring is known as one method for joining superposed metal plates to each other. For this joining, a processing tool having a rod-shaped tool body and a pin projecting on the axial center of one end in the longitudinal direction of the tool body is used. The concave surface gradually decreases in diameter as it goes to the other end side in the direction. And while rotating the said processing tool around the axis center of a tool main body, it moves so that the pin side may be pushed in on the piled metal plate, and the metal plate is pressed by friction heat mutually. Softened and solid-phase bonded.

  By the way, in order to stabilize the quality of the joint formed by the friction stir spot welding, it is necessary to appropriately manage the shape of the processing tool. For example, in Patent Document 1, before a joining operation, a pin of a processing tool is brought into contact with a reference member to detect the position of the processing tool, and the detected position is compared with a reference position of a processing tool stored in advance. By doing so, the wear state of the pin is known.

Japanese Patent Laid-Open No. 2002-292478 (paragraphs 0075 to 0077, FIG. 16)

  However, in Patent Document 1, since it is necessary to bring the pins of the processing tool into contact with the reference member before joining, the production efficiency is lowered by the time of the contact operation of the pins with respect to the reference member.

  In addition, the concave surface formed on the tool body of the processing tool must be controlled because the quality of the joint becomes unstable if the shape changes greatly due to wear. No measures are taken in the apparatus of Document 1.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a friction stirrer capable of managing the shape of a processing tool that affects the quality of a joint without lowering the production efficiency. It is in providing a point joining apparatus.

  In order to achieve the above object, the present invention acquires the waveform of the load applied to the processing tool at the time of joining, and compares the waveform with a reference waveform to know the wear state of the processing tool. Features.

That is, in the present invention, a rod-shaped tool body and a pin projecting on the axial center of one end in the longitudinal direction of the tool body are provided, and the end surface on the pin side of the tool body is the other end in the longitudinal direction of the tool body. A processing tool that is a concave surface that gradually decreases in diameter as it goes to the side, and a direction of an axis of the tool main body that is rotatable around the axis of the tool main body and that overlaps at least two pieces to be joined A tool rotating / moving means for holding the processing tool movably, and connected to the tool rotating / moving means, and the tool rotating / moving means is controlled to rotate the processing tool. A control means for softening the materials to be joined together by frictional heat by moving the pin side of the processing tool so as to push in and pressurizing the materials to be joined. The tool rotation moving means is provided with a load detecting means for detecting a load applied to the processing tool when the processing tool is pressed against the workpiece, and the control means applies to the processing tool at the time of joining. The reference waveform y = f (t) (t is the junction time) stored in advance is stored in advance, and the reference waveform y = f (t) and the load waveform y = g (t ) (T is the joining time), and when g (t) ≦ f (t) in a predetermined continuous section S of the time T from joining start to joining end, the shape of the processing tool is normal. On the other hand, if g (t)> f (t) in the predetermined section S, the shape of the processing tool is determined to be abnormal, and the control means further applies a reference value F1, a load applied to the processing tool. F2 (F1 <F2) and joining start? A reference time t1 (0 <t1 <T) until the concave surface of the tool body comes into contact with the workpiece is stored in advance, and g (t) in a predetermined continuous section S1 of 0 <t <t1. When ≧ F1, it is determined that the pin shape is abnormal. On the other hand, g (t) <F1 in a predetermined section S1 of 0 <t <t1, and in a predetermined predetermined section S2 of t1 <t. When g (t) ≧ F2, it is determined that the shape of the tool body is abnormal.

In the present invention, since the shape of the machining tool can be grasped based on the value of the load applied to the machining tool at the time of joining, it is not necessary to provide time for grasping the shape of the machining tool in addition to the time relating to joining. The shape of the processing tool can be managed without reducing the efficiency.

In the present invention, when joining, it becomes possible to know whether the abnormality of the processing tool is due to the shape of the pin or the shape of the concave surface of the tool body. There is no need to visually evaluate the shape of the processing tool, and it is possible to quantitatively evaluate the shape abnormality in the processing tool without lowering the production efficiency.

It is a lineblock diagram of a friction stir spot welding device concerning an embodiment of the present invention. It is sectional drawing which shows the state just before a processing tool contacts a press part in the procedure which joins the overlapped press part. It is sectional drawing which shows the state immediately after the processing tool contacts the press part in the procedure of joining the stacked press parts. It is sectional drawing which shows the state which has pushed the processing tool into the press part in the procedure of joining the superimposed press part. It is a figure which shows the state just before separating a processing tool from a press part in the procedure of joining the superimposed press part. It is the graph which showed the relationship between the elapsed time at the time of implementing joining with the friction stir spot welding apparatus of this invention, and the load added to a processing tool.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature.

  FIG. 1 shows a friction stir spot welding device 1 according to an embodiment of the present invention. The friction stir spot welding device 1 is used for assembling a plurality of plate-like press parts 13 (materials to be joined) by spot welding by friction stirring in an automobile production line. Means).

  The apparatus main body 2 includes a case 3 extending vertically, and the upper end of the case 3 is fastened to the apparatus fixing side R via a bracket Bk.

  A ball nut 4 having a rotation axis oriented in the vertical direction is rotatably provided inside the case 3, and a ball screw 5 passing through the case 3 in the vertical direction is screwed to the ball nut 4. .

  A tool holder 6 having a drive motor (not shown) whose rotation axis is directed in the vertical direction is attached to the lower end of the ball screw 5, and a load cell 6 a (load detection) is installed inside the tool holder 6. Means) is built-in.

  A servo motor-controlled motor 8 having an output shaft 8a extending in the vertical direction is attached to the upper side surface of the case 3, and the output torque of the motor 8 and the rotation angle of the output shaft 8a are detected inside the motor 8. A possible encoder 8b is provided.

  A rubber belt 9 is stretched over the output shaft 8a and the lower end of the ball nut 4 via a pulley (not shown), and when the electric motor 8 is driven to rotate in the forward and reverse directions, the rotational torque is applied to the ball via the belt 9. By being transmitted to the nut 4, the ball nut 4 is rotated forward and backward, and the ball screw 5 is screwed up and down in the vertical direction accordingly.

  The tool holder 6 detachably holds the processing tool 7 by a chuck portion (not shown).

  As shown in FIGS. 2 to 5, the processing tool 7 includes a bar-shaped tool body 7a extending in the vertical direction, and a pin 7b projecting on the axis of the lower end (one longitudinal end) of the tool body 7a. The lower end (pin 7b side) end surface of the tool body 7a is a concave surface 7c that gradually decreases in diameter toward the upper end side (the other end in the longitudinal direction) of the tool body 7a.

  The machining tool 7 is configured such that the axis of the tool body 7 a coincides with the rotational axis C of the tool holder 6 that faces the vertical direction of the drive motor when held by the tool holder 6. The rotation of the drive motor rotates about the rotation axis C.

  Further, the machining tool 7 is movable in the axial direction of the tool body 7 a by the vertical screwing / retracting operation of the ball screw 5.

  As shown in FIG. 1, a pair of clamp jigs 11 that can hold the press part 13 in a posture extending in the horizontal direction are spaced apart in the horizontal direction below the apparatus main body 2.

  A rectangular parallelepiped support block 12 is disposed between the clamp jigs 11 and immediately below the processing tool 7, and the pressed parts 13 held by the clamp jigs 11 on the support block 12. Are supposed to overlap.

  A control panel 10 (control means) for controlling the apparatus main body 2 is connected to the apparatus main body 2.

  As shown in FIGS. 2 to 5, the control panel 10 outputs a rotation start signal to the tool holder 6 to rotate the processing tool 7 and outputs a positive rotation start signal to the electric motor 8. By moving the processing tool 7 toward the overlapping part of the press parts 13 and pressing the pin 7b side of the processing tool 7 into the upper press part 13 to pressurize the press parts 13, the press parts 13 are brought together. It is softened by frictional heat and solid-phase bonded. At that time, the load cell 6 a detects a load applied to the processing tool 7.

  Further, as shown in FIG. 6, the control panel 10 stores in advance a reference waveform Db: y = f (t) (t is a joining time) of a load applied to the processing tool 7 during joining. The reference waveform Db: y = f (t) is compared with the load waveform D: y = g (t) obtained by the load cell 6a (t is the bonding time), and the time from the start of bonding to the end of bonding When g (t) ≦ f (t) in a predetermined continuous section S of T, the shape of the machining tool 7 is determined to be normal, while g (t)> f (t) in the predetermined section S. In this case, the shape of the processing tool 7 is determined to be abnormal.

  Further, the control panel 10 includes reference values F1 and F2 (F1 <F2) of loads applied to the processing tool 7 and from the start of joining until the concave surface 7c of the tool body 7a comes into contact with the press part 13. Reference time t1 (0 <t1 <T) is stored in advance, and when g (t) ≧ F1 in a predetermined continuous section S1 of 0 <t <t1, it is determined that the shape of the pin 7b is abnormal. On the other hand, if g (t) <F1 in a predetermined section S1 of 0 <t <t1 and g (t) ≧ F2 in a predetermined predetermined section S2 of t1 <t, the tool body 7a It is determined that the shape is abnormal.

  Next, a method of joining the stacked press parts 13 with the friction stir spot welding device 1 will be described.

  First, as shown in FIG. 1, each press part 13 is gripped by each clamp jig 11 so that the two press parts 13 overlap on the support block 12.

  Next, the operator presses a joining start button (not shown) provided on the control panel 10. Then, the control panel 10 outputs a rotation start signal to the tool holder 6 and outputs a forward rotation start signal to the electric motor 8, and based on those signals, as shown in FIG. The processing tool 7 is rotated about the rotation axis C, and the ball screw 5 is moved downward via the belt 9 and the ball nut 4 so that the processing tool 7 is moved downward from a predetermined reference position. Moving.

  Thereafter, as shown in FIG. 3, the protruding end of the pin 7 b comes into contact with the upper press part 13. Then, the upper press part 13 starts to be heated by frictional heat, and the load value applied to the processing tool 7 starts to be detected by the load cell 6a.

  Thereafter, when the processing tool 7 further moves downward, as shown in FIG. 4, the pin 7b enters the softened metal portion 13a softened by the frictional heat, and the peripheral edge of the concave surface 7c of the tool body 7a moves to the upper press part 13. Touch (point P in FIG. 6).

  Further, after the processing tool 7 moves downward, the control panel 10 outputs a rotation stop signal to the electric motor 8 at a predetermined timing, and the electric motor 8 stops the rotation of the output shaft 8a based on the signal, thereby the processing tool. The downward movement of 7 is stopped.

  Then, the processing tool 7 is pressed into the pressed parts 13 with a predetermined pressure and maintained for a predetermined time. Then, as shown in FIG. 5, the softened metal portion 13a is solidified to form a joint portion 13b.

  When T time has elapsed from the start of joining, the control panel 10 outputs a reverse rotation start signal to the electric motor 8. Then, the electric motor 8 reversely rotates the output shaft 8a to move the machining tool 7 upward to a predetermined reference position.

  When the processing tool 7 moves to a predetermined reference position, the control panel 10 outputs a rotation stop signal to the tool holder 6, whereby the rotation of the processing tool 7 is stopped and the joining operation is completed.

  FIG. 6 is a graph in which the horizontal axis represents the elapsed time during welding and the vertical axis represents the load applied to the machining tool 7. Db indicates a reference waveform y = f (t) acquired by the processing tool 7 having a reference dimension, D1 indicates a waveform y = g (t) acquired by the processing tool 7 in which the pin 7b is damaged, D2 indicates waveform y = g (t) data acquired by the processing tool 7 in which the pin 7b is in a normal state and the concave surface 7c is worn. The time t1 is a time from when the projecting end of the pin 7b comes into contact with the press part 13 to join the outer peripheral edge of the concave surface 7c with the press part 13 when joining with the processing tool 7 having a reference dimension.

  As shown in the waveform of D1, if the pin 7b is damaged, it can be seen that a larger load is applied to the processing tool 7 immediately after the start of bonding than the waveform of Db, and the protruding end of the pin 7b is pressed. It can be seen that the time from the contact with the part 13 to the contact of the outer peripheral edge of the concave surface 7c with the pressed part 13 is also shorter than t1. Thus, since the value of the waveform g (t) tends to be higher than the reference waveform f (t) when the pin 7b is broken, in the present invention, in the predetermined section S within the elapsed time T. When g (t)> f (t), it is determined that the shape of the processing tool 7 is abnormal.

  When the pin 7b is damaged, the value of the waveform g (t) tends to be higher than the reference waveform f (t) at the elapsed time of 0 <t <t1. If g (t) ≧ F1 in a predetermined section S1 where 0 <t <t1 than the set reference value F1 of the load applied to the processing tool 7, the shape of the pin 7b is determined to be abnormal. Yes.

  In addition, as shown in the waveform of D2, when the pin 7b is in a normal state and the concave surface 7c is worn, the protruding end of the pin 7b comes into contact with the pressed part 13 and then the outside of the concave surface 7c. There is no difference in the value of the waveform g (t) with respect to the reference waveform f (t) until immediately before the peripheral edge contacts the pressed part 13. However, since the value of the waveform g (t) tends to be higher than the reference waveform f (t) in the elapsed time of t ≧ t1, in the present invention, the load applied to the processing tool 7 set in advance is set. G (t) <F1 in a predetermined section S1 where 0 <t <t1 from the reference value F1, and a reference value F2 of the load applied to the machining tool 7 set in advance (assuming F2> F1). In addition, when g (t) ≧ F2 in a predetermined section S2 where t ≧ t1, the shape of the tool body 7a is determined to be abnormal.

  As described above, in the embodiment of the present invention, the shape of the processing tool 7 can be grasped based on the value of the load applied to the processing tool 7 at the time of joining. It is not necessary to provide time for grasping, and the shape of the processing tool 7 can be managed without reducing the production efficiency.

  Moreover, since it becomes possible to know whether the abnormality of the processing tool 7 is due to the shape of the pin 7b or the shape of the concave surface 7c of the tool main body 7a at the time of joining, It is not necessary to visually evaluate the shape of the processing tool 7, and quantitative evaluation can be performed on the shape abnormality in the processing tool 7 without reducing the production efficiency.

  In addition, the reference waveform y = f (t) used in the embodiment of the present invention may use data obtained when the joining work is performed once by using the processing tool 7 of the reference dimension, or the joining work may be performed. You may use the average data at the time of performing several times.

  In the embodiment of the present invention, the load applied to the machining tool 7 is acquired by the load cell 6, but not limited to this, the torque value obtained by the encoder 8 b of the electric motor 8 is substituted as the load applied to the machining tool 7. May be.

  INDUSTRIAL APPLICABILITY The present invention is suitable for a friction stir spot welding device that spot welds stacked metal plates by friction stirring.

1 Friction stir spot welding device 2 Device body (tool rotation moving means)
7 Processing tool 7a Tool body 7b Pin 7c Concave surface 10 Control panel (joining means)
13 Press parts (materials to be joined)

Claims (1)

It has a rod-shaped tool body and a pin projecting on the axial center of one end of the tool body in the longitudinal direction, and the end surface on the pin side of the tool body gradually shrinks as it goes to the other end side in the longitudinal direction of the tool body. A machining tool that is a concave surface to be radiated,
A tool rotation moving means for holding the processing tool so as to be rotatable around the axis of the tool body and movable in the axial direction of the tool body toward a material to be joined that is overlapped by at least two sheets;
Connected to the tool rotation moving means, controls the tool rotation moving means to rotate the machining tool, and moves the pin to be bonded to the material to be bonded to the one side to be bonded. A control means for softening the materials to be joined together by frictional heat by pressurizing the material, and solid-phase joining;
The tool rotation moving means is provided with a load detection means for detecting a load applied to the processing tool when the processing tool is pressed against the workpiece.
The control means stores in advance a reference waveform y = f (t) (t is a joining time) of a load applied to the processing tool during joining, and the reference waveform y = f (t) and the load The load waveform y = g (t) (t is the joining time) obtained by the detecting means is compared, and g (t) ≦ in a predetermined continuous section S of the time T from the joining start to the joining end. In the case of f (t), the shape of the processing tool is determined to be normal, while in the predetermined section S, the shape of the processing tool is determined to be abnormal when g (t)> f (t) ,
Further, the control means includes reference values F1 and F2 (F1 <F2) of loads applied to the processing tool and a reference time t1 (0 <t1) from the start of joining until the concave surface of the tool body comes into contact with the workpiece. <T) is stored in advance, and when g (t) ≧ F1 in a predetermined continuous section S1 of 0 <t <t1, it is determined that the pin shape is abnormal, while 0 <t <t1 When g (t) <F1 in the section S1 and g (t) ≧ F2 in a predetermined continuous section S2 of t1 <t, it is determined that the shape of the tool body is abnormal. A friction stir spot welding device.

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