Paper folding machine

Abstract

A paper folding machine comprising folding mechanisms (11, 15, 24) arranged at folding positions (A-C) on a transport path (1), respectively, guides (8, 19, 20, 28, 29) positioning a paper sheet (F) relative to the folding positions by engagement with at least one side edge of the paper sheet, stoppers (12, 15, 25) stopping and positioning the paper sheet at the folding positions by bringing a leading edge of the paper sheet into contact with the stoppers, a fold misalignment detection unit (50) detecting a fold misalignment amount of the paper sheet for each folding position, and a controller (42) controlling positions of the guides and stoppers. The controller calculates, for each folding position, an average fold misalignment amount, and adjusts the position of the guide and/or stopper associated with the corresponding folding position so as to correct fold misalignment corresponding to the average fold misalignment amount.

1 . A paper folding machine folding a printed paper sheet along at least one fold line preset on a printing surface of the paper sheet so as to form a signature, the paper folding machine comprising:
 a transport path for the paper sheet having an entrance, an exit and at least one folding position which is provided in an intermediate area of the transport path;   at least one transport mechanism transporting the paper sheets one by one along the transport path between the entrance and a most upstream folding position, and between adjacent folding positions, and between a most downstream folding position and the exit;   a folding mechanism arranged at each of the at least one folding position so as to fold the paper sheet along the associated fold line while the paper sheet is stopped at the associated folding position;   at least one adjustable guide positioning the paper sheet relative to the at least one folding position by bringing at least one side of the paper sheet into contact with the at least one adjustable guide;   an adjustable stopper arranged downstream of each of the at least one folding position so as to position and stop the paper sheet at the associated folding position by bringing a leading edge of the paper sheet into contact with the stopper; and   a fold misalignment detection unit detecting, for each paper sheet and for each folding position, a fold misalignment amount, wherein   the position of the at least one guide and/or the stopper associated with the corresponding folding position is adjusted based on detection data of the fold misalignment detection unit, characterized in that   the paper folding machine further comprises:   a drive mechanism capable of moving the at least one adjustable guide and the stopper; and   a controller operatively connected to the drive mechanism, wherein   the controller comprises   a data receiving section receiving the detection data from the fold misalignment detection unit,   a data counting section counting, for each folding position, the number of the detection data received by the data receiving section,   a data storage section storing, for each folding position, the detection data received by the data receiving section,   a statistical processing section calculating, for each folding position, an average fold misalignment amount using the detection data corresponding to a predetermined number of sample each time the number of detection data stored in the data storage section reaches, for each folding position, the number of sample, and   an adjustment section adjusting the position of the at least one guide and/or the stopper associated with the corresponding folding position so as to correct fold misalignment corresponding to the average fold misalignment amount each time the average fold misalignment amount is calculated by the statistical processing section.   
     
     
         2 . The paper folding machine according to  claim 1 , wherein the controller further comprises
 a misalignment tolerance storage section storing, for each folding position, the average fold misalignment amount as a misalignment tolerance, data stored in the misalignment tolerance storage section being updated each time the average fold misalignment amount is calculated by the statistical processing section, and   a folding failure check section operatively connected to the at least one transport mechanism and the folding mechanism, and comparing the detection data with the misalignment tolerance each time the detection data is received by the data receiving section, and stopping the at least one transport mechanism and the folding mechanism when the detection data exceeds the misalignment tolerance.   
     
     
         3 . The paper folding machine according to  claim 1 , wherein the paper folding machine further comprises a collection unit arranged downstream of the most downstream folding position on the transport path or at the exit of the transport path for collecting the paper sheet with folding failure, wherein
 the controller further comprises   a misalignment tolerance storage section storing, for each folding position, the average fold misalignment amount as a misalignment tolerance, data stored in the misalignment tolerance storage section being updated each time the average fold misalignment amount is calculated by the statistical processing section, and   a folding failure check section operatively connected to the collection unit, and comparing the detection data with the misalignment tolerance each time the detection data is received by the data receiving section, and collecting the corresponding paper sheet in the collection unit when the detection data exceeds the misalignment tolerance.   
     
     
         4 . The paper folding machine according to  claim 1 , wherein the statistical processing section of the controller calculates, for each folding position, a standard deviation of the fold misalignment amount using the average fold misalignment amount and the detection data corresponding to the number of sample each time the number of the detection data stored in the data storage section reaches, for each folding position, the number of sample, and further calculates a variation judgement value of fold misalignment based on the standard deviation, wherein
 the controller further comprises   a folding failure check section operatively connected to the at least one transport mechanism and the folding mechanism, and comparing the variation judgement value with a predetermined misalignment tolerance each time the variation judgement value is calculated by the statistical processing section, and stopping the at least one transport mechanism and the folding mechanism when the variation judgement value exceeds the misalignment tolerance.   
     
     
         5 . The paper folding machine according to  claim 1 , wherein the paper folding machine further comprises a collection unit arranged downstream of the most downstream folding position on the transport path or at the exit of the transport path for collecting the paper sheet with folding failure, wherein
 the statistical processing section of the controller calculates, for each folding position, a standard deviation of the fold misalignment amount using the average fold misalignment amount and the detection data corresponding to the number of sample each time the number of the detection data stored in the data storage section reaches, for each folding position, the number of sample, and further calculates a variation judgement value of fold misalignment based on the standard deviation, wherein   the controller further comprises   a folding failure check section operatively connected to the collection unit, and comparing the variation judgement value with a predetermined misalignment tolerance each time the variation judgement value is calculated by the statistical processing section, and collecting the corresponding paper sheet in the collection unit when the variation judgement value exceeds the misalignment tolerance.