JP2005161377A - Welding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the posture control of high degree of freedom and the position control of high accuracy by assembling a robot arm ensuring the rigidity by reducing the length of each arm and forming a hinge consisting of rotary shafts to a moving head in straight motion. <P>SOLUTION: A robot arm having a hinge consisting of three rotary shafts is assembled to orthogonal straight moving shafts of XYZ modeled by a machine tool, and the adjacent rotary shafts of the robot arm are orthogonal to each other. Flexible posture control can be performed at an arm tip part thereby, the rigidity and the positional accuracy can be ensured by suppressing each arm joined with the joint to the necessary and sufficient length, and high function can be realized by mounting a semi-conductor welding unit DL, an auxiliary tool T and various kinds of sensors S on a tip of the robot arm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a welding apparatus having a mechanical configuration that has excellent rigidity and can be positioned with high accuracy and high speed.

Conventionally used welding apparatuses are considered to be roughly classified into two types in terms of machine configuration and function.
As shown in FIG. 16, the first configuration is composed of a combination of a robot arm having a relatively long reach and a transport rail using a linear movement axis for transporting the robot arm. The robot arm is mainly operated during processing, and it is desirable in terms of accuracy to stop the robot transport rail at a fixed position during processing.
If you synchronize the transfer rail at high speed simultaneously with the operation of the robot arm, the tip of the robot arm will be shaken and the machining accuracy will be significantly reduced. With regard to the transfer rail, we will specialize in moving the robot arm to a fixed position. In general, the positioning accuracy at the intermediate position is not good.
In such a configuration, the joint portion of the robot arm is generally constituted by a rotating shaft, the processing is performed by the robot arm alone, and each of the robot arms constituting the robot arm is secured in order to ensure a wide movable range of the robot arm tip. I have to lengthen the arm.
In addition, since the multiple joints that connect each arm are composed of rotation axes, the calculation load for coordinate calculation is large, and the accumulation of errors is significant due to the long arm length, improving the position accuracy of the arm tip. Have difficulty.
Even if you try to correct the error, you can easily imagine that the limit that can be corrected is low, and the machine configuration with long arms and many joints has poor rigidity, and can always provide stable accuracy due to errors, deflection, twisting, etc. is not. In particular, in precision welding, it can be easily imagined that even if the control of the weld line is maintained continuously and with high accuracy, the limit on the machine configuration will be hit immediately. (For example, refer to Patent Document 1.)
In general, in such a machine configuration, the machining program is often based on teaching rather than direct programming.
Therefore, it is difficult to think of a use that always follows high precision for severely set welding lines, and it is not used for precise welding that requires high-precision position accuracy, but its own accuracy. Naturally, the scope of operation has been limited due to its low level.
Further, in the configuration of such a robot with a long arm length, it is desirable to make the arm tip lighter, and it is not common to mount additional units such as a welding unit and various sensors on the arm tip.

The second configuration of the conventional example is such that a complex rotating shaft is attached as an additional shaft to a base portion that moves linearly with high accuracy, reminiscent of a machine tool, and an example is shown in FIG.
In this case, the rotating shafts are combined in close proximity, and the rotating shafts are controlled simultaneously during movement. (For example, see Patent Documents 2 to 5.)
This method has an advantage that an error can be suppressed to a relatively small value by mainly using a linear movement axis that can be positioned with high accuracy and at a high speed and by arranging the rotation axes close to each other.
However, the range that can be moved only by the rotating shaft is very narrow, and it is rare that machining is achieved by moving only the rotating shaft, and most of the movement is accompanied by the movement of the base part at the same time. Since the rotary shaft unit occupies the surrounding space, it easily interferes with the workpiece, making it difficult to handle a workpiece having a complicated shape.
Moreover, the unit of the rotating shaft has a low degree of design freedom for attaching various sensors and auxiliary processing tools. For example, a method of passing the laser inside the rotating shaft and guiding the laser beam with a reflecting mirror installed at the rotating shaft is also conceivable, but this method always shifts the optical axis of the laser beam or breaks the reflecting mirror. I have to be aware of such troubles.
Another possible method is to transmit laser light through an optical fiber and bring it to the tip. However, attention must always be paid to energy loss and fiber damage when passing through the optical fiber.

In recent years, there has been a demand for improvements in accuracy and machining speed for welding machines, but there is also a demand for flexibility that can flexibly handle various workpieces.
However, as described above, conventional robot arm-based methods and linear movement axis-based methods have merits and demerits, and the user must inevitably select either method and accept the disadvantages derived from that method. It was.
JP 06-301411 A JP 10-175085 A JP 11-221692 A JP 05-138390 A JP-A-06-190581

  In the present invention, the high accuracy of positioning cannot be ensured in the robot arm-based processing, which has been used in conventional welding processing, and a rotary shaft is additionally attached and positioning is always performed on a linear moving shaft. It is intended to provide a novel welding apparatus that requires simultaneous control of a plurality of axes, easily interferes with a complicated workpiece shape, and as a result, has limited the object to be machined.

  The configuration of the present invention is based on a high-precision, high-rigidity and high-speed linear movement shaft modeled on a machine tool, which is combined with a robot arm that secures rigidity by setting each arm length short. Accordingly, it is possible to secure the flexibility of movement by the robot arm while minimizing the deterioration of the positioning accuracy of the arm tip, and to cope with the load of an appendage on the arm tip.

  The welding apparatus of the present invention has an advantage that good accessibility and freedom of movement can be obtained by a robot arm without impairing speed, accuracy, rigidity, and the like.

  The present invention is based on a linear movement axis modeled on a machine tool, combined with a robot arm with a short arm length, and enables flexible machining by the robot arm without losing rigidity, accuracy, etc. A configuration that can withstand the weight of additional devices such as sensors and tools mounted on the tip has been realized. Hereinafter, the specific embodiment will be described.

FIGS. 1 to 3 show a first embodiment of the present invention, which is a combination example of one rotation axis R1 and one linear movement axis G1 for moving the rotation axis R1.
The arm A is attached to the attachment surface B of the moving body Z that moves by a linear axis.
1 to 3 have a limited configuration of one rotation axis R1 and one linear axis, and the movable range of only the rotation axis is an arc, but the movement of the arm tip that combines the rotation axis and the linear axis is possible. The range has a degree of freedom of movement which is cylindrical in the example of FIGS. 1 and 2 and flat in FIG.
Since these have the simplest configuration, the movable range is limited, but a fixed type is sufficiently practical, and it is easy to secure rigidity and has excellent positioning accuracy.
In addition, when the arm type robot is limited to such an extent that the rigidity of the arms A1 and A2 connected to the rotation shaft can ensure the rigidity, an image sensor or a weld bead is provided at the tip of the arm robot. Various sensors S for measurement, auxiliary tools T for deburring and shaping the workpiece W, and a laser unit L such as a semiconductor laser unit can be easily attached.
The robot arm A considering the length of the first arm A1 and the second arm A2 constituting the arm A and considering the securing of rigidity can withstand the weight of the laser unit L and withstand the cutting load of the auxiliary tool T. Will not cause a displacement.
Therefore, the welding operation for the workpiece W as shown in the figure can be performed without impairing the speed, accuracy, rigidity, and the like.

4 to 7 show a second embodiment of the present invention, which is a combination example of two rotation axes R1 and R2 and two linear movement axes G1 and G2 for moving the rotation axes R1 and R2.
Compared to the movable range being cylindrical or flat in the first embodiment, the movable range can have a three-dimensional expansion in the second embodiment.
In the case of two rotating shafts, the movable range by only controlling the rotating shaft is considerably widened, but simultaneous operation with the linear moving shaft is necessary for efficient operation.
In any case, the combination of the above two rotating shafts with the movable head that can move in a two-dimensional direction enables more complex movements and facilitates welding to the free-form workpiece W.
Further, the welding operation for the workpiece W as shown in the figure can be performed without impairing the speed, accuracy, rigidity, and the like.

FIGS. 8 to 9 show a third embodiment of the present invention, which is a combination example of three rotation axes R1, R2, and R3 and three linear movement axes G1, G2, and G3 for moving the rotation axes. is there.
In the present embodiment, even if only three linear movement axes are operated, the movement can be made to an arbitrary place in the three-dimensional space, and if the three rotation axes do not interfere with the workpiece W and its surroundings, the three straight lines can be moved. Operation is possible only by controlling the position of the shaft, and very high-precision machining is possible with a moving head that is rich in rigidity.
The configuration of FIG. 8A is an example, and is set such that adjacent rotation axes of three rotation axes are orthogonal to each other. The configuration of the rotating shaft is ideal, and the degree of freedom of the tip portion is increased by the appropriately arranged rotating shaft, and the laser unit L, the auxiliary tool T, and the sensor S attached to the tip are always appropriately set. It can be turned in the direction, and it is difficult to generate a blind spot in the work.
FIG. 8 (b) shows a case where the rotary shafts R1 and R2 are moved in the configuration of FIG. 8 (a). By such movement of the rotary shaft, various devices provided at the tip can be freely set. Attitude control is possible.

In the configuration of FIG. 9A, two rotation axes R2, R3 among the three rotation axes R1, R2, R3 are set in parallel. When the rotation axis is set in this way, the posture control of various devices provided at the tip is limited as compared with the case where the adjacent rotation axes are arranged orthogonally as described above, but as shown in FIG. As described above, it is possible to move the tip portion linearly while maintaining the posture of the device provided at the tip by controlling the two rotation shafts R2 and R3 with the linear movement shaft fixed. .
According to said structure, highly accurate linear movement is realizable by control only of a rotating shaft, avoiding interference with a workpiece | work.
Further, the welding operation for the workpiece W as shown in the figure can be performed without impairing the speed, accuracy, rigidity, and the like.

Furthermore, FIG. 10 shows a realistic form of the third embodiment in which the three rotational axes R1, R2, and R3 are set to be orthogonal to each other in the third embodiment. The three linear movement axes G1, G2, and G3 are set as orthogonal XYZ axes, and the arm A1 is attached to the movable body Z that moves linearly through the rotation axis R1 that can rotate in the normal direction of the movable body. The arms A1 and A2 are coupled by a rotation axis R2 orthogonal to the rotation axis R1, and the tip is coupled by an arm A2 and a rotation axis R3 orthogonal to the rotation axis R2.
The number of rotating shafts that drive each arm is three, the cross-sectional area of each arm is wide, and the length of each arm is set short, so that sufficient rigidity is ensured even at the tip of the arm, and the accuracy is high. Maintained at the same level.
Thereby, the welding operation | work with respect to the workpiece | work W can be performed without impairing speed, accuracy, rigidity, etc.

Therefore, there is no problem even if a load is applied to the tip, and the transmitter of the semiconductor laser unit LD that is heavy can be installed at the tip. This eliminates transmission loss of laser light and eliminates the danger of leakage of laser light in the intermediate path as compared with a case where an external transmitter is provided.
In recent years, the quality check of welding has been strictly demanded, and welding processing and various measurements and inspections related to it have become indispensable. The image sensor S1 and the laser scanner S2 corresponding to this have been installed at the tip. Can be installed.
In the image sensor S1, it is possible to monitor the melting state by capturing the light emission state of the welded portion as a luminance distribution, and to reflect the monitoring result in laser light output control or the like in real time.
In the laser scanner S2, the three-dimensional shape of the welded weld bead can be captured in detail, and a weld defect can be inspected quickly.
The various sensors as described above are also freely controlled in posture by the three rotation axes R1, R2, and R3, so that highly accurate measurement is always possible.

Furthermore, an auxiliary tool T can also be installed at the tip for improving the quality of welding and preventing the occurrence of defective products. FIG. 11 shows a case where a router is set as an example of the auxiliary tool. A cutting tool C is attached to the tip of the router T, which can be cut by being rotated by a motor CH. This router is usually stored in a state of being retracted by the cylinder CH, but is advanced by the cylinder CH as necessary.
As shown in FIG. 12, even if the end surface of the workpiece W is uneven as shown by E1, the end surface can be processed and formed by E.2 using the router T.
As described above, by forming the workpiece W before welding, the welding conditions are remarkably improved, the welding quality is maintained at a high level, and the welding defects due to the variation of the workpiece are drastically reduced.

  By mounting not only the welding unit but also various sensors and auxiliary tools on the robot arm tip as described above, each additional device functions as much as possible, and each additional device is closely linked. Therefore, it is possible to increase the added value of the welding apparatus itself.

Further, the tip portion is not limited to the configuration described above. Various combinations are possible depending on the required conditions. An example is shown in FIG.
The laser beam irradiated from the welding head at the tip is transmitted through the optical fiber LF and is set so as to be able to supply the filler wire F for welding. S1 and S1 are installed together as various sensors. . In various forms, various sensors for monitoring the welding state and the processing location are significant.

Next, FIG. 14 shows an embodiment in which a robot arm having three linear movement axes and the above three rotation axes is combined.
FIG. 14 shows that the robot arm can be freely moved by three orthogonal XYZ axes, and the X-axis moving body is set wide so that deformation due to torsion hardly occurs even when a load is applied to the robot arm. It is considered so. The length of each arm of the robot arm is set to be short and the radius of the joint portion is ensured to ensure sufficient rigidity and power, and the semiconductor laser unit LD, various sensors S, auxiliary tools provided at the tip portion are secured. These postures can be freely controlled while withstanding the load of T.

FIG. 15 is obtained by changing the configuration of the XYZ axes with respect to the above.
By making the Z axis the final movement axis among the linear axes, the accessibility of the entire robot arm in the Z axis direction is advantageous.
And the laser unit L is installed outside, this is transmitted with the optical fiber LF, and the laser beam is emitted from the tip of the robot arm.
Compared with the example of FIG. 14, since there is no laser transmitter that is the heaviest, the tip is lighter, which makes the arm of the robot arm slightly narrower and can be handled with a smaller driving force of the rotating shaft. . In addition, since the tip is compact, the accessibility to the workpiece is further enhanced. As described above, an optimal axis configuration can be set according to the form, type, number, and the like of the device installed at the tip of the robot arm.

  As mentioned above, if the effect of the welding apparatus of this invention is mentioned specially, the welding operation with respect to a workpiece | work can be performed, without impairing speed, precision, rigidity, etc. Furthermore, for precision welding, it is necessary to make the spot diameter of the welding beam as small as possible and to control the welding line with high precision together with pre-processing of the workpiece to be welded. This is possible, and can be applied to any free form without reducing accuracy.

  If a gripping device is attached to the tip of the robot arm, welding can be performed while fixing a small part, and it is also possible to cope with internal bending and the like.

1 shows a welding apparatus of the present invention and is a configuration diagram with one linear movement shaft and one rotation shaft. 1 shows a welding apparatus of the present invention and is a configuration diagram with one linear movement shaft and one rotation shaft. 1 shows a welding apparatus of the present invention and is a configuration diagram with one linear movement shaft and one rotation shaft. 1 shows a welding apparatus of the present invention and is a configuration diagram with two linear movement axes and two rotation axes. FIG. 1 shows a welding apparatus of the present invention and is a configuration diagram with two linear movement axes and two rotation axes. FIG. 1 shows a welding apparatus of the present invention and is a configuration diagram with two linear movement axes and two rotation axes. FIG. FIG. 2 shows a welding apparatus of the present invention and is a configuration diagram with three linear movement shafts and three rotation shafts. FIG. 2 shows a welding apparatus of the present invention and is a configuration diagram with three linear movement shafts and three rotation shafts. FIG. 2 shows a welding apparatus of the present invention and is a configuration diagram with three linear movement shafts and three rotation shafts. It is a specific example of a robot arm. It is a block diagram of an auxiliary processing apparatus. It is a perspective view explaining the process by the mounted auxiliary tool. It is a perspective view which shows the structure of the front-end | tip part at the time of transmitting the processing laser with an optical fiber. It is the perspective view which showed the specific Example by this invention. It is the perspective view which showed the specific Example by this invention. It is a block diagram of the conventional welding machine. It is a block diagram of the conventional welding machine.

Explanation of symbols

A Robot arm A1 First arm A2 Second arm A3 Third arm B Robot arm attachment part E1 Edge part E2 Material edge part C after correction Cutting tool CH Motor CL Cylinder L Laser unit DL Semiconductor laser unit LB Laser light LF Optical fiber F Filler wire H Welding head R1 First rotation axis R2 Second rotation axis R3 Third rotation axis G1 First linear axis G2 Second linear axis G3 Third linear axis S Sensor S1 Image sensor S2 Laser scanner T Auxiliary tool (Luther)
W Work V Weld bead Z Moving object

Claims (11)

A moving apparatus controlled to linearly move in a one-dimensional direction is equipped with a posture control head having a single rotation axis for posture control in one direction, and a welding apparatus provided with a welding head on the posture control head . A moving head of a moving body controlled to orthogonally move in at least two-dimensional directions is equipped with a posture control head having two rotation axes for posture control in at least two directions, and this posture control head includes a welding head. Welding equipment. A moving head controlled to move orthogonally in a three-dimensional direction is equipped with a posture control head having three rotation axes that control the posture in a three-dimensional direction, and this posture control head is equipped with a welding head. apparatus. The welding apparatus according to claim 1, wherein the one rotation axis for posture control is constituted by a robot arm joint. The welding apparatus according to claim 2, wherein the two rotation shafts for posture control are constituted by robot arm joints. The welding apparatus according to claim 3, wherein the three rotation shafts for posture control are constituted by robot arm joints. The welding apparatus according to any one of claims 1 to 6, wherein the welding head includes a laser beam output unit capable of emitting a processing laser beam. 7. The welding apparatus according to claim 1, further comprising a CCD or CMOS image sensor for measuring a weld pool and a weld bead in the vicinity of the welding head. The welding apparatus according to claim 1, further comprising a three-dimensional laser scanner for measuring a weld bead in the vicinity of the welding head. The welding apparatus according to any one of claims 1 to 6, further comprising a cutting tool for processing an end face or the like of the steel plate in the vicinity of the welding head. 7. The welding apparatus according to claim 1, wherein a length of each arm constituting the robot arm is set to be short.

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