Apparatus for taking out molded product using vacuum sucker with controller that determines sucking operation start time based on a stable time interval

A system for taking out a molded product, comprising:

• a vacuum sucker including a suction member operable to suck up a molded product, a vacuum generator connected to the suction member via a pipe to apply a vacuum pressure to the suction member, a pressure valve provided in the pipe between the vacuum generator and the suction member to allow and block communication between the vacuum generator and the suction member, and a pressure detector operable to detect a pressure in the pipe between the pressure valve and the suction member;
• a moving mechanism operable to move the suction member to transport the molded product to a release position after the molded product is pushed out of a mold of a molding machine by an ejector pin and sucked up by the suction member and then taken out;
• and
• a controller configured to execute operation control for the vacuum generator and the pressure valve and movement control for the moving mechanism,
• the controller being configured to start operation of the suction member to suck up the molded product after the pressure in the pipe reaches a predetermined pressure before the suction member sucks up the molded product, concurrently with the movement control for the moving mechanism, wherein:
• the controller includes a time interval measuring section configured to measure a stable time interval since the pressure in the pipe reaches the predetermined pressure until a sucking operation start pressure is detected judging from an output from the pressure detector, the sucking operation start pressure indicating that the suction member starts operation to suck up the molded product with the predetermined pressure being maintained;
• and
• the controller determines a sucking operation start time such that the stable time interval is longer than a bias time interval before the suction member sucks up the molded product, concurrently with the movement control for the moving mechanism, wherein:
• the controller is configured to:
• acquire, in a first take-out cycle, a time interval since a time when the pressure detector detects the predetermined pressure until a time when the pressure detector detects the sucking operation start pressure which indicates that the suction member has sucked up the molded product as an initial stable time interval from the time interval measuring section, in a course of the vacuum generator starting sucking operation by opening the pressure valve at an original sucking start position determined in advance and the moving mechanism performing operation to move the suction member closer to the molded product with a time when the suction member passes the original sucking start position being defined as 0,
• acquire, in second and subsequent take-out cycles, the stable time interval since the pressure detector detects the predetermined pressure until the pressure detector detects the sucking operation start pressure from the time interval measuring section in a course of the vacuum generator starting sucking operation by opening the pressure valve and the moving mechanism performing operation to move the suction member closer to the molded product when the time interval measuring section measures a delay time interval from time 0 determined on a basis of the initial stable time interval and a number of take-out cycles so as to become longer as the number of take-out cycles is increased,
• continue the second and subsequent take-out cycles while changing the delay time interval stepwise, and determine the delay time interval which renders the stable time interval longer than the bias time interval as an allowable delay time interval, and
• thereafter determine a time when the allowable delay time interval has elapsed since the time 0 as the allowable sucking operation start time.

A system for taking out a molded product, comprising:

• a vacuum sucker including a suction member operable to suck up a molded product, a vacuum generator connected to the suction member via a pipe to apply a vacuum pressure to the suction member, a pressure valve provided in the pipe between the vacuum generator and the suction member to allow and block communication between the vacuum generator and the suction member, and a pressure detector operable to detect a pressure in the pipe between the pressure valve and the suction member;
• a moving mechanism operable to move the suction member to transport the molded product to a release position after the molded product is pushed out of a mold of a molding machine by an ejector pin and sucked up by the suction member and then taken out;
• and
• a controller configured to execute operation control for the vacuum generator and the pressure valve and movement control for the moving mechanism,
• the controller being configured to start operation of the suction member to suck up the molded product after the pressure in the pipe reaches a predetermined pressure before the suction member sucks up the molded product, concurrently with the movement control for the moving mechanism, wherein:
• the controller includes a time interval measuring section configured to measure a stable time interval since the pressure in the pipe reaches the predetermined pressure until a sucking operation start pressure is detected judging from an output from the pressure detector, the sucking operation start pressure indicating that the suction member starts operation to suck up the molded product with the predetermined pressure being maintained;
• and
• the controller determines a sucking operation start time such that the stable time interval is longer than a bias time interval before the suction member sucks up the molded product, concurrently with the movement control for the moving mechanism, wherein
• the controller is configured to:
• acquire, in first to n-th take-out cycles where n is an integer of two or more, a time interval since a time when the pressure detector detects the predetermined pressure until a time when the pressure detector detects the sucking operation start pressure which indicates that the suction member has started operation to suck up the molded product as an initial stable time interval from the time interval measuring section, in a course of the vacuum generator starting sucking operation by opening the pressure valve at an original sucking start position determined in advance and the moving mechanism performing operation to move the suction member closer to the molded product with a time when the suction member passes the original sucking start position being defined as 0, and determine a data analysis value for n initial stable time intervals as an initial stable time interval to be used thereafter,
• acquire, in (n+1)-th and subsequent take-out cycles, the stable time interval since the pressure detector detects the predetermined pressure until the pressure detector detects the sucking operation start pressure from the time interval measuring section in a course of the vacuum generator starting sucking operation by opening the pressure valve and the moving mechanism performing operation to move the suction member closer to the molded product when the time interval measuring section measures a delay time interval from time 0 determined on a basis of the initial stable time interval and a number of take-out cycles so as to become longer as the number of take-out cycles is increased,
• continue the (n+1)-th and subsequent take-out cycles while changing the delay time interval stepwise, and determine the delay time interval which renders the stable time interval longer than the bias time interval as an allowable delay time interval, and
• thereafter determine a time when the allowable delay time interval has elapsed since the time 0 as the allowable sucking operation start time.