Patent ID: 12246474

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention will be described in detail below with reference to the drawings.FIG.1is a block diagram illustrating a schematic configuration of an apparatus1for taking out a molded product according to an embodiment of the present invention.FIG.2is a time chart, specifically before and after detection of a collision, according to the present embodiment.FIG.3illustrates an example of display on an input section23. The apparatus1conveys a vertical frame5using a conveying mechanism7with three orthogonal axes. The vertical frame5includes, at its distal end, a take-out head3operable to go into a mold of a molding machine and take out a molded product. A plurality of servomotors9with an encoder10are used as drive sources for the conveying mechanism7. A control system11configured to control the plurality of servomotors9includes a servo system control section13provided for the plurality of servomotors9. The servo system control section13calculates the deviation between a detected value of a position detected by the encoder10and the value of a position command and the deviation between a detected value of a speed detected by the encoder10and the value of a speed command, and performs feedback control on the position and the speed of drive shafts of the servomotors9, as a drive portion, using the deviations. The servo system control section13functions as a so-called servoamplifier.

In the present embodiment, the control system11includes a manual command generation section14, a teaching data acquisition section15, a torque detection section17, a collision detection section19, and a deviation clearing section21. The manual command generation section14generates a manual command for manually operating the servo system control section13. The teaching data acquisition section15acquires and stores teaching data by performing operation necessary to perform appropriate operation during teaching. As illustrated inFIG.2, the torque detection section17detects torque [see (B) inFIG.2] applied to the vertical frame5or the take-out head3when the servomotor9is manually operated as the manual command generation section14provides a movement command [see (A) inFIG.2] to the servo system control section13through a manual operation input from the input section23. In the present embodiment, the torque detection section17is configured to detect torque in the transverse direction, torque in the pull-put direction, and torque in the vertical direction that act on the take-out head3. The torque may be detected by measuring a motor current, or may be detected using a torque sensor. In the present embodiment, as illustrated inFIG.3, three torque indications (indications of “40%”, “150%”, and “30%” inFIG.3) that are proportional to the magnitude of the torque in the transverse direction, the torque in the pull-put direction, and the torque in the vertical direction are displayed on a display screen of a display portion24of the input section23which serves as a controller that is used to input a manual operation. In addition, the display screen of the display portion24is configured to display three suggestion indications (a white circular mark and a black circular mark inFIG.3) adjacent to the three torque indications, the suggestion indications each suggesting the direction of retraction. The suggestion indications may be any of text indications, mark indications, lamp indications, etc. Such indications allow an operator to correctly determine, based on data, torque in which direction should be reduced through retraction when retracting operation is performed after a collision. The indications also allow even an unskilled operator to easily perform retracting operation after a collision.

The collision detection section19outputs an operation stop command by assuming that the take-out head3has collided with a peripheral or neighboring object when a value detected by the torque detection section17becomes larger than a predetermined value. In the present embodiment, as illustrated in (B) inFIG.2, the collision detection section19sets the predetermined value to a value (limit value×α %; e.g. α=50%) that is smaller than a limit value (e.g. 300% of rated torque) during automatic operation. Determining the predetermined value in this manner prevents application of a load that is more than necessary to a peripheral or neighboring object at the time of a collision or during retracting operation by a manual operation performed during work such as teaching or while performing retracting operation after a collision. In the present embodiment, in addition, the collision detection section19outputs an operation stop command [see (E) inFIG.2] by assuming that the take-out head3has collided with a peripheral or neighboring object when the collision detection section19detects continuously for a predetermined time T1[see “β seconds” in (B) inFIG.2] that the value detected by the torque detection section17is larger than the predetermined value. If a collision is immediately determined when the torque has become more than the predetermined value, a collision may be erroneously determined when a tapping operation is performed etc. Therefore, the occurrence of a collision is determined when the torque is continuously more than the limit value×α % also after a period of β seconds (specifically 0.2 to 0.3 seconds) has elapsed.

Further, the collision detection section19outputs an alarm signal [see the error flag in (C) inFIG.2] almost at the same time as the operation stop command is output. After that, the alarm signal [error flag in (C) inFIG.2] is continuously output until a predetermined time [see γ seconds in (B) inFIG.2] elapses (time T2) after the value detected by the torque detection section17becomes smaller than the predetermined value (after the flag is set to 0) after a movement command is input again (the timing of “movement in reverse direction” in (A) inFIG.2is reached) from the manual command generation section14to the servo system control section13by operating the input section23, in order to perform a retracting operation. The limit value×α % does not immediately become zero, since the torque is gradually reduced to zero from the collision state, even if a movement command for “movement in reverse direction” is input. An alarm25generates an alarm for the worker through a sound, an image, etc. while the alarm signal is output. The stand-by time T2of γ seconds is set in order to give the worker a chance to perform a retracting operation again when the worker has performed an erroneous retracting operation. That is, when the torque in the pull-put direction is high because of a collision, it is necessary to move the vertical frame5in the direction of bringing the torque in the pull-put direction to zero. If the worker performs a manual operation to move the vertical frame5in the vertical direction, however, the vertical frame5may be moved in the vertical direction with the take-out head3strongly pressed against a colliding object, which may break the take-out head3. Thus, the stand-by time T2of γ seconds is set in order to provide a time required for the worker to make a correct determination.

The deviation clearing section21performs deviation clearing operation to bring the deviations computed in the servo system control section13for the servomotors to zero with the servo system control section13kept on when the operation stop command is output from the collision detection section19. In the present embodiment, as illustrated in (D) inFIG.2, clearing operation is performed again [see (D) inFIG.2] when a movement command [see (A) inFIG.2] is input again through a manual operation.

With the control system according to the present embodiment, the deviation clearing section21performs clearing operation to bring the deviations in the servo system control section to zero with the servo system control section kept on when the operation stop command is output from the collision detection section19. Therefore, positioning is completed as the deviations are brought to zero, which enables operation corresponding to the manual command to be performed again. If the deviations are not brought to zero, operation for the deviations is performed prior to a manual command for retracting operation. This operation may damage the take-out head3. In the present embodiment, however, such a problem is not caused. In the present embodiment, when an escaping operation is performed after the operation is stopped, the servomotors9can be operated according to an operation command from the input section23to move the vertical frame5(take-out head3), which allows smooth retraction from the collision state.

FIG.4is the actual flow of operation at the time when a collision is detected. In step ST1, it is determined whether or not the torque value is larger than a predetermined value (limit value×α %). When the determination result is No, a manual operation is executed in step ST2, and the shafts are moved by driving the servomotors9in step ST3. Then, in step ST4, it is determined again whether or not the torque value is larger than the predetermined value (limit value×α %). When the determination result is Yes, the process proceeds to step ST5, where it is determined whether the time T1of a timer is zero. When the determination result is Yes, the timer starts counting in step ST6, and the process proceeds to step ST7. The process proceeds to step ST7also when the result of the determination in step ST5is No, and the timer continues counting. Next, in step ST8, it is determined whether or not the time T1of the timer is β. If it is β, the process proceeds to step ST9. The process returns to step ST1if the determination result is No. If the result of the determination in step ST4is No, the process proceeds to step ST41. It is determined whether or not the time T1of the timer is zero. If the determination result is No, the timer is turned off in step ST42, the time T1of the timer is brought to zero in step ST43, and the process returns to step ST2. The process returns to step ST2also when the result of the determination in step ST41is Yes. If it is determined in step ST8that the time T1of the timer has been brought to the error flag is turned on in step ST9, and the stop process is executed in step ST10. After that, the deviations are cleared in step ST11, an error pop-up (error indication) is displayed as an alarm in step ST12, and a buzzer is sounded as an alarm in step ST13. After that, the timer is turned off in step ST14, and the time T1of the timer is brought to zero in step ST15. Through the operation described above, the deviations are reset with the servo system control section kept on after a collision is detected.

FIG.5is the flow of operation for collision retraction. In this example, collision retraction is performed when the torque value is larger than the limit value×α % at the start. In step ST21, it is determined whether or not the torque value is smaller than the limit value×α %. When the torque value is not smaller than (is equal to or more than) the limit value×α %, the process proceeds to step ST22, where a manual operation is executed. In step ST23, the deviations are cleared, and the operation stop command is turned off. In step ST24, the shafts are moved by driving the servomotors. After that, in step ST25, it is determined whether or not the torque value is smaller than the limit value×α %. When the torque value is smaller than the limit value×α %, the process proceeds to step ST26, where it is determined whether or not the time T2of the timer is zero. When the time T2of the timer is zero, the timer starts counting in step ST27. When the time T2of the timer is not zero, the timer continues counting in step ST28. When the torque value is not smaller than the limit value×α % in step ST25, the process proceeds to step ST251, where it is determined whether or not the time T2of the timer is zero. If the time T2of the timer is zero, the process returns to step ST21. If the time T2of the timer is not zero, the process proceeds to step ST252, where the timer is turned off. The timer period T2is brought to zero (initialized) in step ST253, and the process returns to step ST21. It is determined in step ST29whether or not the time of the timer has been brought to γ after the timer counts the time in step ST28. If the determination result is No, the process returns to step ST21. If the determination result is Yes, the process proceeds to step ST30for collision retraction operation, where the error flag is turned off. The buzzer is turned off in step ST31, counting of the time T2of the timer is turned off in step ST32, and the time T2of the timer is brought to zero (initialized) in step ST33. Consequently, retraction from the collision state has been made.

[Modifications]

Preferably, the torque detection section is configured to detect the action direction of torque that acts on the take-out head from a variety of directions. When servomotors are provided for a large number of axes such as five axes and six axes, for example, the torque detection section may be configured to detect torque for all the large number of axes. When the take-out head is mounted to a posture controller, the torque detection section may be configured to detect torque applied from the posture controller to the take-out head as well. Preferably, the display portion of the input section that is used to perform a manual operation is configured to display all the torque indications that are proportional to the magnitude of the torque detected by the torque detection section. Such torque indications may be displayed in any manner such as numerical display, bar-graph display, and meter display. Preferably, the display portion of the input section is configured to display a suggestion indication adjacent to the torque indication, the suggestion indication suggesting the direction of retraction. This suggestion may be any of a text indication, a mark indication, a lamp indication, etc.

INDUSTRIAL APPLICABILITY

With the present invention, the deviation clearing section performs clearing operation to bring the deviations in the servo system control section to zero with the servo system control section kept on when the operation stop command is output. Therefore, positioning is completed as the deviations are brought to zero, which enables operation to be performed again. As a result, when a retracting operation is performed after the operation is stopped, the servomotor can be operated according to an operation command to move the vertical frame and the take-out head, which allows smooth retraction from the collision state.