JP3577858B2 - Work transfer robot control method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control method of a robot, and more particularly to a control method in a case where a work transfer robot cannot normally grip a work (mis-grip).
[0002]
[Prior art]
Industrial robots (hereinafter simply referred to as robots) are of many types and are used in various manufacturing processes.
[0003]
By the way, automobile production is one of the industries in which this industrial robot is frequently used. A forging process is an indispensable step in the production of parts that require high strength in automobile parts.
[0004]
Various robots are also used in the forging process, but in using such robots, their control is very important.
[0005]
In a forging press, which is one of the hot forging processes, advanced automation using a robot is performed. There are various types of robots used in forging presses.For example, in a work transfer robot that takes in and out a work between press dies, it is necessary to transfer the work between press dies before the work cools down. Usually, one cycle of rough forming, rough forming, finish forming and the like is conveyed in about 14 to 20 seconds. Therefore, if the work transfer robot stops for some reason, pressing cannot be performed naturally, and the heated work gradually cools down and cannot be forged.
[0006]
There are various causes for stopping the work transfer robot, such as a failure of the robot itself or an emergency stop due to other causes during the forging process. Among them, there is a so-called misgrip in which the work transfer robot fails to grasp the work.
[0007]
In general, a robot is controlled (programmed) so as to stop on the spot when it misgrips. Some of them are controlled so that the motion trajectory up to that point after the misgrip is moved backward.
[0008]
[Problems to be solved by the invention]
However, in the forging process, if the robot stops due to misgrip, the work cools down as described above and forging cannot be performed. There is a problem that it will lead to the loss of. In addition, if it takes time to evacuate the robot to recover from an abnormality, the robot hand part will be in close proximity to a high temperature (around 1200 ° C.) workpiece for a long time, and will be exposed to necessary abnormal heat. In some cases, the time required for the operation becomes longer, which may cause unexpected failures.
[0009]
In addition, when control is performed to return the motion trajectory backward, it is necessary to perform a program for returning later and an operation teaching separately from a program and an operation teaching for a normal operation. There is a problem that it takes a lot of time to program the robot and teach operation.
[0010]
Therefore, an object of the present invention is to provide a work transfer robot used in a forging process, in which the robot does not stop at the time of misgrip, and minimizes the program man-hours and teaching man-hours of the robot so as to control the robot more easily. Is to provide a way.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a hand provided at a tip of a robot arm clamps a workpiece, and a clamp confirmation that confirms that a sensor provided at the hand clamps the workpiece. In the control method of the work transfer robot, which outputs a signal and receives the clamp confirmation signal and is controlled to move to the next operation, after receiving the clamp confirmation signal and before starting the next operation, A confirmation step of confirming that the hand has clamped the work, and outputting an unclamping command to keep the hand open when the hand cannot clamp the work in the confirmation step; Outputting a pseudo clamp confirmation signal to the robot based on the output of the unclamping command; A step of returning to the origin position by the normal operation of the received robot No., during returning the robot which has received the pseudo clamp confirmation signal to the home position, when further outputs a clamp command signal for the hand Outputting a unclamping command and outputting a pseudo-clamp confirmation signal to the robot.
[0013]
Further, the invention of claim 2, in the configuration of claim 1, wherein the workpiece transfer robot is a control method for workpiece transfer robot, characterized in that used in the forging process.
[0014]
Further, the invention of claim 3, wherein, in the configuration of claim 2, wherein said forging step is a method of controlling workpiece transfer robot, which is a hot forging process.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
[0016]
Hereinafter, first, the outline of the forging press process and the work transfer robot will be described, and then the control method of the work transfer robot to which the present invention is applied will be described.
[0017]
The forging press step is well known, but here, as an example, a step of forming a forged product by first, second, and third press steps as shown in FIG. 1 will be described. First, a material billet as a work 90 heated by an electromagnetic induction heater (not shown) is placed in a first pressing step 10P by a billet loader 50, and a press machine (the press machine body is not shown, only the lower mold is shown) Press). Then, the work 90 is handled by the transfer robot 10, placed on the second press 20P, and pressed by the press. Further, the work 90 is handled by the transfer robot 10, placed on the third press 30P, and pressed by the press. Finally, the work 90 is handled by the transfer robot 10 and placed on the locate plate 60. The work 90 placed on the locate plate 60 is moved to a trim press step 80 by the manipulator 70, deburred, and transferred to a predetermined pallet (not shown) by the work transfer conveyor 85.
[0018]
As shown in FIG. 2, the work to be forged is subjected to deburring of the heated raw material burette 90 ′ through the first press 10P, the second press 20P, and the third press 30P, and finally, the completed work. 90 ".
[0019]
The above is the outline of the forging press. Here, the work transfer robot 10 sequentially transfers the work 90 from the first press 10P to the locate plate 60, and it takes about 14 to 20 seconds.
[0020]
As shown in FIG. 3, the work transfer robot 10 is a robot that performs a three-axis operation of an X axis (one horizontal direction), a Z axis (a vertical direction), and an S axis (a horizontal plane rotation direction).
[0021]
This robot is provided with X-axis, Z-axis, and S-axis movable parts on a carriage 101 for moving the robot itself, and the carriage 101 can be fixed to the floor by a fixing jig 102. ing.
[0022]
The X-axis movable section 111 moves the robot arm 15 in the X-axis direction to move the hand 18 in and out of the press, and adjusts the position of the hand 18 in the X-axis direction in accordance with the movement of the S-axis. The X-axis operation is driven by a motor 11, and the motor 11 is provided with an encoder 21 for detecting the amount of operation.
[0023]
The Y-axis movable section 112 is used to position the hand 18 in the up-down direction, is driven by the motor 12, and is provided with an encoder 22 for detecting the operation amount.
[0024]
The S-axis movable section 113 is for horizontally rotating the robot arm 15, and the robot arm 15 is composed of two arms 15a and 15b (see FIG. 1). Rotate horizontally while keeping. The S-axis is driven by a motor 13, and is provided with an encoder 23 for detecting the operation amount.
[0025]
As described above, the work 90 is conveyed from the first press 10P to the locate plate 60 via the second press 20P and the third press 30P by the operation of each axis. In the work gripping operation by the hand 18, the hand is inserted between the upper die and the lower die of the press machine, and in this state, the hand 18 is moved downward so as to grip the work from above.
[0026]
A hand 18 provided at the end of the robot arm 15 is provided with a non-contact type proximity switch (not shown), which detects that the work has been gripped or mis-grip.
[0027]
The hand 18 is opened and closed by an air cylinder, a hydraulic cylinder, or the like (both are not shown), and the opening and closing are performed by opening and closing an air valve or an oil valve of each cylinder.
[0028]
The robot controller controls this robot. FIG. 4 is a block diagram illustrating a control system of the robot.
[0029]
The robot controller 30 includes an operation processing module 31 for controlling the entire operation of the robot, a positioning module 32 for performing an accurate positioning operation of the distal end arm of the robot arm, and an exchange of signals between the robot and the outside. I / O module 33. The actual robot controller is an ordinary sequencer, computer, or the like, and the above-described modules function as the modules by executing necessary programs by the CPU of the sequencer or the computer.
[0030]
The operation processing module 31 stores the taught operation locus of the robot and controls the operation of the robot itself according to the taught contents. The speed control command of each motor of the robot and the opening / closing operation command of the robot hand 18 are provided. , Transmitting and receiving an interlock signal.
[0031]
The positioning module 32 receives a speed control command from the operation processing module, sends out a pulse signal for actually operating the motor, and receives a signal from each encoder to calculate the operation amount of the robot arm. It is controlled so that it is moved to an appropriate position. The signal output from the positioning module 32 is transmitted to the motors 11, 12, and 13 via an amplifier circuit (AMP) 41, and the pulse signals from the encoders 21, 22, and 23 are transmitted via the amplifier circuit 41. To the positioning module 32.
[0032]
The I / O module 33 exchanges signals with the outside, and performs protocol conversion and the like as necessary. The output signal is an operation signal for transmitting the current operation status to a host computer that manages the entire forging press process and a display computer for displaying the operation status, and other robots and press machines etc. , An interlock signal for preventing contact of the hand, a valve opening / closing signal for operating the hand, and the like. On the other hand, input signals include a hand opening confirmation signal from a hand opening / closing confirmation sensor, a hand closing confirmation signal, an interlock signal, and a control signal from a host computer.
[0033]
Next, the control of the work transfer robot configured as described above will be described. FIG. 5 is a flowchart showing a control procedure of the robot.
[0034]
First, a program required for robot operation is executed by the operation processing module, the number of operation steps, which is the operation trajectory of the robot, is cleared (A1), and it is determined whether all steps are completed (A2). The positioning of the operation step is performed (A3). As a result, in the case of the first operation, the robot moves along the trajectory of the operation step 1, and the operations after the operation step 2 are sequentially executed. If all the operations have been completed in the program step A2, a normal end signal is output (A8), and the program ends. After that, if there is a necessary robot operation, the program is executed upon receiving a normal end signal.
[0035]
Next, after positioning, it is determined whether or not a clamp command has been output (A4). If the clamp command has not been issued, it is confirmed that the apparatus is in the unclamped state in order to operate the next operation step. (A7), and returns to the program step A2 to operate the next operation step. When the clamp command is issued, it is determined whether or not the hand 18 has clamped. If the clamp is OK, the process returns to the program step A2 to operate the next operation step.
[0036]
On the other hand, if it is not confirmed in the program step A5 that the clamp has been made, that is, if it is a misgrip, a misgrip process described later is performed.
[0037]
FIG. 6 is a subroutine flowchart of the misgrip process.
[0038]
When a misgrip is detected, first, to warn the user of the misgrip, a message to that effect is displayed or a signal notifying the misgrip is transmitted to the host computer (B11).
[0039]
Next, an unclamping signal (valve open) is issued to the hand 18, and the hand 18 is completely opened so that the work is not caught on the hand 18 (B12). Then, only the clamp confirmation signal is output (the signal in this case is referred to as a clamp confirmation pseudo signal for the sake of explanation, but the signal itself is exactly the same as that during normal operation) (B13). The reason for outputting this clamp confirmation pseudo signal is that if the clamp confirmation cannot be made here, the robot operation will stop thereafter, so the clamp confirmation pseudo signal will be output to stop the robot operation. This is in order not to let them.
[0040]
Next, it is determined whether or not the robot position is at the origin position (B14), and the operation of the next operation step is performed as it is (B15). In other words, even if the workpiece is not gripped by the misgrip, the operation of the robot itself operates with the same motion trajectory as in a normal case.
[0041]
Next, since the robot is operated in the same manner as the normal operation, it is determined whether or not there is a clamp command output during that time (B16). If there is no clamp command, unclamping is confirmed (B20). Return to B14.
[0042]
On the other hand, when a clamp command is output, an unclamping command is output, clamping is stopped (B17), and after unclamping is confirmed (B18), a clamp confirmation pseudo is performed so as not to stop the operation. A signal is output (B19), and the program returns to program step B14.
[0043]
When it is determined in the program step B14 that the robot is at the home position, the robot is stopped so that the robot does not operate any more (B21), and the abnormal termination is output (B22).
[0044]
The operation of the robot at the time of misgrip according to the above procedure will be described together with the operation trajectory in the process. FIG. 7 shows an example of the motion trajectory of the robot when the workpiece is transferred from the second press 20P to the third press 30P.
[0045]
First, as shown in the drawing, the robot hand 18 moves through operation step 1 and operation step 2 to clamp the work 90 in the second press 20P. Then, the work 90 is gripped by the clamp command. If a misgrip occurs, the clamping of the work is stopped by the misgrip processing described above, but the operation itself of the robot returns to the origin position through a normal operation path. That is, the robot returns to the home position through Step 3 which is an operation for transferring the work to the third press 30P, and Steps 4 and 5 for the robot to return to the home position after transferring the work.
[0046]
As described above, by applying the present invention, at the time of occurrence of misgrip, the robot can be returned to the home position without stopping the robot and without performing a special avoidance operation. Therefore, since the press machine is not stopped due to the stop of the robot, it takes a long time to avoid the stopped robot and the work other than the mis-grip work does not cool down as in the related art. This is particularly effective when, for example, a plurality of press dies are attached to one press machine.Since only the mis-griped work is popped out and other work can be pressed as usual, Less waste.
[0047]
【The invention's effect】
According to the present invention described above, the following effects can be obtained for each claim.
[0048]
According to the first aspect of the present invention, when the robot hand misgrips, a clamp confirmation signal for confirming that the hand has clamped the work is output to the robot while maintaining the open state of the hand. Then, after the misgrip, the robot is returned to the origin position by a normal operation, so that the robot does not stop at the time of the misgrip. In addition, there is no need to set a special operation path for returning the robot to the home position at the time of misgrip. In addition, after the step of outputting a clamp confirmation signal to the robot, while returning the robot to the home position, if a clamp command signal is further output, an unclamping command is output to the hand, On the other hand, since the clamp confirmation signal is output to the robot, even if a command for further clamping is issued during the normal operation after the misgrip, the clamp is actually removed due to the misgrip. The robot can return to the origin position through the normal operation path without causing a problem such as clamping the next work even though the work transfer cannot be continued.
[0050]
According to the second aspect of the present invention, in the forging process, the control according to the first aspect is performed, so that the robot automatically returns to the home position when a misgrip occurs. Evacuation work is not required, and work jumping out work due to misgrip can be easily performed.
[0051]
According to the third aspect of the present invention, in the hot forging step, the control according to the second aspect is performed, so that when a misgrip occurs, the robot automatically returns to the origin position by a normal operation. Therefore, the robot, the hand, and the like do not approach the high-temperature work for a long time than in the normal operation, and it is possible to prevent adverse effects due to heat of the robot and the hands.
[Brief description of the drawings]
FIG. 1 is a drawing for explaining a forging press process.
FIG. 2 is a view for explaining a work formed by the process shown in FIG. 1;
FIG. 3 is a drawing for explaining a work transfer robot.
FIG. 4 is a block diagram for explaining a control system of the robot.
FIG. 5 is a flowchart illustrating a control procedure of the robot.
FIG. 6 is a subroutine flowchart of a misgrip process shown in FIG. 5;
FIG. 7 is a diagram illustrating an example of a motion locus of a robot.
[Explanation of symbols]
10. Work transfer robot,
15 ... Robot arm,
18 ... hand 30 ... robot controller,
31 ... operation processing module
32 ... Positioning module,
33 ... I / O module,
111 ... X-axis movable part,
112 ... Y axis movable part,
113 ... Z-axis movable part.

Claims (3)

The hand provided at the end of the robot arm clamps the work, and the sensor provided on the hand outputs a clamp confirmation signal to confirm that the sensor has clamped the work. In the control method of the work transfer robot controlled to move,
After receiving the clamp confirmation signal and before starting the next operation, a confirmation step of confirming that the hand clamps the work,
Outputting the unclamping command to maintain the open state of the hand when the hand cannot clamp the workpiece in the checking step;
Outputting a pseudo clamp confirmation signal to the robot based on the output of the unclamping command;
Returning the robot receiving the pseudo clamp confirmation signal to the home position by normal operation;
If the clamp command signal is output while the robot receiving the pseudo clamp confirmation signal is returning to the home position, an unclamping command is output to the hand, and a pseudo clamp confirmation signal is output to the robot. And outputting the
A method for controlling a work transfer robot, comprising: The method according to claim 1, wherein the work transfer robot is used in a forging process. The method according to claim 2, wherein the forging step is a hot forging step.

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