JP4630172B2 - Friction stir welding apparatus and control method thereof - Google Patents

Description

  The present invention relates to a friction stir welding apparatus using a robot and a control method thereof.

Conventionally, a friction stir welding apparatus using a robot is known (see, for example, Patent Document 1). This friction stir welding apparatus includes a rotary tool at the tip of an articulated robot arm, and the rotary tool can be moved three-dimensionally by the robot arm. A probe to be inserted into a mating portion of members (hereinafter referred to as “joining members”) to be joined to each other is attached to the tip of the rotary tool. In this friction stir welding apparatus, when the rotating probe moves along the target joining line set at the mating portion of the joining member, the joining member is plastically fluidized by frictional heat with the probe. And the joining members will be joined by cooling and solidifying the plastic fluidized joining members.
Japanese Patent Laying-Open No. 2002-103061 (see paragraphs 0027 to 0033, FIG. 2)

  However, in this friction stir welding apparatus, when the probe of the rotary tool is moved along the target joining line, the robot arm receives the reaction force that the rotary tool receives from the joining member, so the so-called portal type friction stir welding is performed. Unlike the apparatus, there is a problem in that the probe moves greatly deviating from the target joining line due to the lateral force generated as the probe rotates.

  Then, the subject of this invention is providing the friction stir welding apparatus which can prevent that a rotary tool slip | deviates from the target joining line of a joining member, and its control method.

The present invention that solves the above-described problems is a friction stir welding apparatus in which a rotary drive unit that rotates a rotary tool and a pressure drive unit that presses the rotary tool against a joint part of a joining member are arranged at the tip of a robot arm. Then, the amount of deviation between the position of the rotary tool and the position of the target joint line is estimated based on the relationship between the feed amount of the rotary tool and the amount of deviation obtained in advance, and the joining member is compared with the target joint line. The apparatus further includes a correction unit that corrects the position of the rotary tool.
Generally, when the joining members are joined together at the mating portion, the amount of movement of the rotary tool, which is the distance (displacement amount) between the position of the rotary tool and the position of the target joining line, Obtained as a function of rotational speed. In this friction stir welding apparatus, the correction means estimates the amount of movement of the rotary tool based on this function and forces the position of the rotary tool relative to the target joining line of the joining member by correcting the position of the rotary tool. It becomes.

  According to the friction stir welding apparatus and the control method thereof of the present invention, it is possible to prevent the rotary tool from being displaced from the target joining line of the joining member.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a perspective view of a friction stir welding apparatus according to the present embodiment, FIG. 2 is a configuration explanatory view of a pressurization drive unit, a rotation drive unit, and a control unit of the friction stir welding apparatus, FIG. These are the expansion perspective views of a rotary tool.

  As shown in FIG. 1, the friction stir welding apparatus 1 includes a robot arm 10, a C-shaped jig 7, a rotary tool 2, a camera C, a work table 8, and a control unit 9 (see FIG. 2). ). The camera C corresponds to a “photographing unit” in the claims, and the control unit 9 corresponds to a “feedback control unit”. The camera C and the control unit 9 constitute “forcing means” in the claims.

The robot arm 10 moves the rotary tool 2 attached to the tip of the robot arm 10 three-dimensionally, and includes a turntable 11 and a main arm 12.
The turntable 11 rotates the main arm 12 about an axis substantially perpendicular to the installation surface of the friction stir welding apparatus 1.
One end of the main arm 12 is attached via a joint 13 a provided with a shaft member 14 that pivotally supports the turntable 11, and is rotatable around the shaft member 14. The main arm 12 includes a first arm 12a, a second arm 12b, and a third arm 12c that are connected to each other from the turntable 11 toward the tip. The first arm 12a and the second arm 12b are connected via a joint 13b, and the second arm 12b and the third arm 12c are connected via a joint 13c. In the friction stir welding apparatus 1, similarly to the known robot arm, the joint 13 a, the joint 13 b, the joint 13 c and the third arm 12 c with respect to the turntable 11 are driven by the hydraulic system (not shown). The tip position can be moved three-dimensionally. Incidentally, the turntable 11 may be driven by a motor.

  The C-shaped jig 7 is attached to the distal end of the third arm 12c and extends from the distal end side of the third arm 12c so as to detour in a substantially C-shape. The C-shaped jig 7 is rotatable around the central axis of the third arm 12c by driving the joint 13c.

As shown in FIG. 2, inside the C-shaped jig 7 is enclosed, a first servo motor 3, a ball screw 4, a linear motion bearing 5, a second servo motor 6, a rotary tool 2, A camera C and a roller R are arranged. The first servo motor 3 corresponds to a “pressure driving unit” in the claims, and the second servo motor 6 corresponds to a “rotation driving unit”.
The first servo motor 3, the ball screw 4, and the linear motion bearing 5 are attached to the upper inside of the C-shaped jig 7 via a mounting bracket (not shown), and the second servo motor 6 is a linear motion bearing. The rotary tool 2 and the camera C are attached to the second servo motor 6. The roller R is attached to the lower side inside the C-shaped jig 7. Incidentally, the work table 8 to which the joining member 20 described later is attached is disposed between the rotary tool 2 and the roller R.
The first servo motor 3 transmits a rotational force to the ball screw 4 via the drive belt 3a.
The ball screw 4 converts the rotational force transmitted from the first servomotor 3 into direct power, and transmits this direct power to the linear motion bearing 5.
The linear motion bearing 5 moves the second servo motor 6 toward the joining member 20 side by the direct power transmitted from the ball screw 4 or the second servo motor 3 rotates in the reverse direction. 6 is moved away from the joining member 20.
The second servo motor 6 rotates the rotary tool 2 attached at a position facing the roller R.

  As shown in FIG. 3, the rotary tool 2 includes a shank 2b and a probe 2a. The shank 2 b is rotated by the second servomotor 6 and presses the surface of the joining member 20. The probe 2 a is a rod-like member that protrudes from the shank 2 b toward the roller R (see FIG. 2) side, and is a portion that is pushed into the joining member 20. Since such a rotary tool 2 is attached to the tip of the robot arm 10 (see FIG. 1) via a C-shaped jig 7 (see FIG. 1), its position can be moved three-dimensionally. It has become.

  As shown in FIG. 3, when the probe 2a of the rotary tool 2 is pushed into the joining member 20 and moves so as to follow a target joining line 21 described later, the camera C photographs the target joining line 21. It is attached to the 2nd servomotor 6 so that it can do. And the camera C is for the main control part 9c (refer FIG. 2) mentioned later to detect the difference (gap) between the position of the target joining line 21 and the position of the probe 2a by image | photographing the target joining line 21. A detection signal (imaging signal) is output to the main controller 9c. The camera C is not particularly limited as long as it is a known camera capable of transmitting an imaging signal described later, and for example, an infrared camera or the like can be used.

  As shown in FIG. 1, the work table 8 supports a plate-like joining member 20 as a work to be joined, and is arranged on a base 22 arranged on the installation surface of the friction stir welding apparatus 1. Yes. The work table 8 is mainly composed of a flat plate-like support base 8a disposed on the base 22 side, a plurality of support pillars 8b erected on the upper surface of the support base 8a, and a clamp device 8c. . The support base 8a is disposed at a distance from the base 22, and this distance is set to such an extent that the lower side of the C-shaped jig 7 to which the roller R is attached can be received. . The support pillar 8b supports the back surface of the joining member 20 at the top. The support column 8b that supports the edge of the joining member 20 is provided with a clamp device 8c that sandwiches the edge of the joining member 20 with the top of the support column 8b.

  As shown in FIG. 2, the control unit 9 is mainly composed of a rotary tool control unit 9a, a pressurization control unit 9b, and a main control unit 9c.

  The rotary tool control unit 9a sets predetermined rotation conditions such as a rotation speed, a rotation torque, and a rotation direction in the second servomotor 6 according to a command from the main control unit 9c. That is, the rotation condition is set according to the feed rate of the probe 2a, the material and thickness of the joining member 20, and the like. Incidentally, the rotation of the second servo motor 6 by the rotary tool controller 9a is performed via an inverter or the like (not shown).

  The pressurization control unit 9b sets predetermined rotation conditions such as a rotation speed, a rotation torque, and a rotation direction in the first servomotor 3 according to a command from the main control unit 9c. That is, the rotation condition is set according to the pushing amount of the probe 2a into the joining member 20, the approaching / separating speed when the probe 2a approaches or separates from the joining member 20, and the like. Incidentally, the rotation of the first servo motor 3 by the pressurization control unit 9b is performed via an inverter or the like (not shown).

Based on the detection signal output from the camera C, the main control unit 9c detects a difference (distance) between the position of the target joining line 21 (see FIG. 3) and the position of the probe 2a. Then, the main controller 9c moves the probe 2a by performing feedback control so that the detected difference is eliminated, that is, the position of the probe 2a matches the position of the target joint line 21. Incidentally, in the feedback control in the present embodiment, control is performed on the hydraulic pressure of the hydraulic system (not shown) that drives the joint 13a, the joint 13b, the joint 13c, and the turntable 11 shown in FIG. Will move.
The main controller 9c also rotates the first servo motor 3 and the second servo motor 6 at a predetermined timing when the friction stir welding apparatus 1 (see FIG. 1) is activated. Thus, it is comprised so that a command signal may be output to the pressurization control part 9b and the rotary tool control part 9a. The main control unit 9c is set in advance according to the material and thickness of the joining member 20, the amount by which the probe 2a is pushed into the joining member 20, the approach / separation speed when the probe 2a approaches or separates from the joining member 20, and the like. A command signal is output to the pressurization control unit 9b and the rotary tool control unit 9a so that the first servo motor 3 and the second servo motor 6 rotate under a predetermined rotation condition on the basis of the set rotation conditions. Has been.

Next, the control method of the friction stir welding apparatus 1 will be described while appropriately explaining the operation of the friction stir welding apparatus 1 according to the present embodiment with reference to the drawings.
In this friction stir welding apparatus 1, a joining member 20 is disposed on a support column 8b of a work table 8 shown in FIG. At this time, the arrangement position of the joining member 20 is set to a position where the edges of the joining members 20 face each other in the butt joining, and in the overlap joining, the joining members 20 are in contact with each other. Are set at positions where their edges overlap each other. And the joining member 20 is fixed on the top part of the support pillar 8b by the clamp apparatus 8c.

  Next, as shown in FIG. 3, a target joining line 21 that is a target joining line is set in a joining portion (butting portion or overlapping portion) between the joining members 20. The target joining line 21 may be any marker that can be photographed by the camera C. For example, the target joining line 21 may be a line drawing drawn with paint on the butted portion or the overlapping portion, or a marking line engraved on the overlapping portion. It may be. Further, as long as the camera C can shoot, the target joining line 21 may be the butted portion itself.

  In the friction stir welding apparatus 1, the second servomotor 6 is positioned at a position where the camera C can bring the starting end of the target joining line 21 into view. At this time, as shown in FIG. 2, a roller R attached to the C-shaped jig 7 is disposed below the work table 8, and on the joining member 20 fixed on the support column 8b. The rotating tool 2 attached to the C-shaped jig 7 is arranged. Such positioning of the second servo motor 6 is performed by the position of the start end of the target joining line 21 (see FIG. 3) in the joining member 20 fixed to the work table 8 and the initial position of the second servo motor 6 (friction stir welding). The main control unit 9c stores the relationship with the position of the second servo motor 6 at the time of activation of the apparatus 1 (see FIG. 1), and the main control unit 9c is shown in FIG. 1 based on this storage. This can be performed by drivingly controlling the joint 13a, the joint 13b, the joint 13c, and the turntable 11 of the main arm 12.

  Next, the rotary tool controller 9a shown in FIG. 2 rotates the second servo motor 6 based on a command signal from the main controller 9c. Then, the probe 2a of the rotary tool 2 rotates under preset rotation conditions. Moreover, the pressurization control part 9b rotates the 1st servomotor 3 on the preset rotation conditions based on the command signal from the main control part 9c. As a result, the ball screw 4 moves the second servo motor 6 toward the joining member 20 through the linear motion bearing 5 when the rotational force of the first servo motor 3 is transmitted. The probe 2a that has reached the starting end of the target joining line 21 is pushed into the starting end of the target joining line 21 while rotating, and the joining of the joining member 20 starts. At this time, the work table 8 is supported by the roller R disposed below the work table 8. Incidentally, in this friction stir welding apparatus 1, even if the load of the rotary tool 2 on the surface of the joining member 20 increases, the rotary tool 2 is caused by the elasticity when the C-shaped jig 7 shown in FIG. The reaction force received from the joining member 20 is absorbed.

  Then, as shown in FIG. 3, the probe 2 a is pushed into the joining member 20 and moves while the shank 2 b of the rotary tool 2 presses the surface of the joining member 20 with a predetermined pressing force. Is plastic fluidized by frictional heat. In addition, the joining members 20 that are plastically fluidized are cooled and solidified, so that the joining members 20 are joined together by the target joining line 21.

  On the other hand, the main control unit 9c (see FIG. 2) allows the main arm 12 shown in FIG. 1 to move so that the probe 2a (see FIG. 3) moves along the target joining line 21 (see FIG. 3). The joint 13a, the joint 13b, the joint 13c, and the turntable 11 are driven and controlled. However, the probe 2a tends to move greatly away from the target joining line 21 due to the lateral force generated as the probe 2a rotates. At this time, the friction stir welding apparatus 1 is controlled as follows.

  Below, the control method of the friction stir welding apparatus 1 which concerns on this embodiment is demonstrated, referring drawings suitably. In the drawings to be referred to, FIG. 4 is a flowchart for explaining a control method of the friction stir welding apparatus 1 according to the present embodiment.

As shown in FIG. 4, the main controller 9c (see FIG. 2) captures and outputs the target joint line 21 (see FIG. 3) captured by the camera C (see FIG. 2). The position detection signal is input (step S1). The main controller 9c (see FIG. 2) detects a difference ΔX (distance) between the position of the target joint line 21 (see FIG. 3) and the position of the probe 2a (see FIG. 3) based on this detection signal. (Step S2). Incidentally, the difference ΔX is represented by the shortest distance between the position of the target joint line 21 (see FIG. 3) and the position of the probe 2a (see FIG. 3).
Next, as shown in FIG. 4, the main controller 9c (see FIG. 2) moves the probe 2a (see FIG. 3) so as to eliminate the difference ΔX (step S3). Then, Step S1 to Step S3 are repeated.

  According to such a control method, the main control unit 9c (see FIG. 2) having received the detection signal from the camera C (see FIG. 2) connects the probe 2a (see FIG. 3) to the target joint line 21 (see FIG. 3). ) To move along. As a result, as shown in FIG. 3, in the friction stir welding apparatus 1, the rotating probe 2 a moves following the target joining line 21.

  According to the friction stir welding apparatus 1 and the control method thereof as described above, the probe 2a is prevented from deviating from the target joining line 21 of the joining member 20, so that the joining members 20 can be accurately targeted according to the original aim. It can be joined by the joining line 21.

In addition, this invention is implemented in various forms, without being limited to the said embodiment.
In the above embodiment, the forcing means is constituted by the camera C and the main controller 9c. However, in the friction stir welding apparatus according to the present invention, the forcing means is a guide member provided along the target joining line 21. May be. FIG. 5A is a view partially showing the friction stir welding apparatus of the present invention, and is a perspective view showing a state of a work table in which a guide member is attached to the clamp device, and FIG. The figure which looked at the state of the rotary tool from A direction in (a), FIG. 6 is a conceptual diagram which shows a mode that the guide member was attached to the back surface of a work table (support stand). In FIG. 5A, FIG. 5B, and FIG. 6, the same components as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIG. 5A, in the friction stir welding apparatus 1, a guide member 25 is attached to the work table 8. The guide member 25 is a long member disposed along the target joining line 21. As shown in FIG. 5B, the guide member 25 is connected to a support member 25a extending upward from the clamp device 8c. As shown in FIGS. 5A and 5B, when the second servo motor 6 comes into contact with the guide member 25, the probe 2a of the rotary tool 2 is connected to the target joining line 21 (see FIG. 5). 5 (a)) is arranged at a position where it can be guided so as to follow.
In the friction stir welding apparatus 1, the guide member 25 guides the rotary tool 2 to force the position of the rotary tool 2 with respect to the target welding line 21. As a result, in this friction stir welding apparatus 1, the probe 2 a can move the probe 2 a so as to follow the target joining line 21 without changing the control of the friction stir welding apparatus 1.

  Moreover, the guide member 25 may be arrange | positioned so that the target joining line 21 (refer Fig.5 (a)) may be followed by the back surface of the support stand 8a, as shown in FIG. The guide member 25 is disposed at a position where the probe 2a of the rotary tool 2 can be guided so as to follow the target joining line 21 (see FIG. 5A) when the roller R comes into contact with the guide member 25. Yes.

In the friction stir welding apparatus of the present invention, the forcing unit may be a correction unit configured to correct the position of the rotary tool with respect to the target welding line by estimating the amount of movement of the rotary tool.
In general, when joining members are joined at a mating part (butting part or overlapping part), the amount of movement of the rotary tool, which is the distance (displacement amount) between the position of the rotary tool and the position of the target joining line Is obtained as a function of the rotational speed of the rotary tool.
FIG. 7 referred to here is a schematic diagram showing a state in which the probe is displaced from the target joining line when the rotating probe joins the joining member.
As shown in FIG. 7, when the probe 2 a rotating at a rotational speed N (rpm) is pushed into a joining member (not shown) to join the joining member along the target joining line 21, The position of the probe 2a deviates from the target joining line 21. The amount of deviation ΔX of the probe 2a per unit length of the target joint line 21 is determined by the force (W) generated around the rotating probe 2a, the resistance (ρ) when the probe 2a moves, and the like. .

  In the friction stir welding apparatus 1 here, data of a deviation amount ΔX (see FIG. 7) is obtained in advance by experiments, and the position of the probe 2a (see FIG. 3) is corrected based on the data of this deviation amount ΔX. Thus, the main controller 9c (see FIG. 2) is configured. Specifically, a map representing the relationship between the feed amount of the probe 2a (see FIG. 3) and the deviation amount ΔX (see FIG. 7) is created, and the main control unit 9c (see FIG. 2) refers to this map. The correction amount of the deviation amount ΔX can be set according to the actual feed amount of the probe 2a. That is, the main control unit 9c is configured to drive and control the joint 13a, the joint 13b, the joint 13c, and the turntable 11 of the main arm 12 shown in FIG. 1 so as to correct the deviation amount ΔX. It becomes. The main controller 9c (see FIG. 2) here corresponds to “correcting means” in the claims. According to the friction stir welding apparatus 1, the position of the probe 2 a can be forced only by control, so that the friction stir welding apparatus 1 can be prevented from being enlarged. Further, this control method may be performed together with feedback control.

1 is a perspective view of a friction stir welding apparatus according to an embodiment. It is structure explanatory drawing of the pressurization drive part of a friction stir welding apparatus, a rotation drive part, and a control part. It is an expansion perspective view of a rotary tool. It is a flowchart for demonstrating the control method of the friction stir welding apparatus which concerns on embodiment. FIG. 5A is a view partially showing the friction stir welding apparatus of the present invention, and is a perspective view showing a state of a work table in which a guide member is attached to the clamp device, and FIG. It is the figure which looked at the state of the rotary tool from A direction in (a). It is a conceptual diagram which shows a mode that the guide member was attached to the back surface of a work table (support stand). It is a schematic diagram which shows a mode that a probe shifts | deviates from a target joining line, when the rotating probe joins a joining member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Friction stir welding apparatus 2 Rotary tool 2a Probe 2b Shank 3 1st servomotor (pressure drive part)
6 Second servo motor (rotary drive)
9 Control unit (feedback control unit: forcing means)
DESCRIPTION OF SYMBOLS 10 Robot arm 20 Joining member 21 Target joining line 25 Guide member C Camera (imaging part: Forcing means)

Claims (1)

A rotary drive for rotating the rotary tool;
A friction stir welding apparatus in which a pressure drive unit that presses the rotating tool against a joint of a joining member is disposed at the tip of a robot arm,
The amount of deviation between the position of the rotary tool and the position of the target joint line is estimated based on the relationship between the feed amount and the amount of deviation of the rotary tool obtained in advance, and the rotary tool with respect to the target joint line of the joining member A friction stir welding apparatus further comprising correction means for correcting the position of the friction stir welding apparatus.

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