JP2019112193A - Defect detecting device by use of ultrasonic wave - Google Patents

Abstract

An object of the present invention is to provide a defect detection device for detecting foreign matters such as a piece of paper adhered to a sheet and defects such as a corner break of a sheet by ultrasonic waves in a sheet conveying unit of a printing press. A defect detection device according to the present invention is installed in front of a printing unit in a printing press, such as a piece of paper on a conveyance table that conveys a sheet supplied from a supply unit of the printing press to the printing unit. An ultrasonic detection mechanism for detecting foreign matter and sheet loss is provided. By comparing the waveform detected by the ultrasonic detection mechanism with the reference waveform, the defect is detected. [Selection] Figure 1

Description

  The present invention relates to a defect detection device for detecting foreign matter such as a piece of paper attached to a sheet by ultrasonic waves in a sheet conveyance unit of a printing press.

  Generally, in a printing machine, stacked sheet-fed sheets are fed into a feeder unit, and the printing machine is operated to feed sheets one by one in a stream system, and feed the sheet to a printing unit through a conveyance table. Be done. In the printing unit, printing is performed on one side by feeding a sheet between a plate cylinder to which various types of ink are supplied and an impression cylinder disposed opposite to the plate cylinder to apply pressure. After that, printing is performed on both sides of the sheet via the printing unit located downstream and performing printing on the other side. The sheet subjected to printing is fed to a discharge pile to complete a series of printing steps.

  It is not easy to determine the sheet conveyed by the stream feeder method if the sheet has a defect such as the adhesion of a foreign substance because the sheets overlap and are passed. In particular, in the case where a piece of paper due to sheet breakage mixes between the sheet and a corner break in which the corner portion of the sheet is broken, visual detection is impossible because the sheets overlap.

  Temporarily, if it is not possible to detect a defect such as mixing of paper pieces or creases, it will be conveyed to the printing unit as it is, and if it is printed in the mixed state, a printout of the printed pattern will occur. In addition, dents due to excessive printing pressure will be generated in the plate surface and the portion in contact with the paper of the impression cylinder, and if dents occur in the plate surface and impression cylinder, they can not be used for printing in that state, so they need to be replaced. There is. Although the printing plate is replaced every month, the impression cylinder is removed once from the machine to replace the impression cylinder, and an outside contractor handling the heavy equipment will be asked to carry it out, which will result in enormous expenses as repair costs and overhead expenses. .

  As a method for detecting the state of loss of the sheet during transport, optical detection that detects without contact, electrostatic capacitance detection, eddy current detection, differential transformer detection that detects with contact, and potentiometer detection Etc.

  As an example of a detection method, a feeder including a detection unit for inspecting a sheet loss state in a feeder unit of a printing press, a mark for detection in advance printed on a margin of the sheet, and an inspection unit having a determination unit for determining angular breakage of the sheet There is disclosed an apparatus for detecting a missing state of a sheet by detecting the presence or absence of a detection mark by the apparatus (see, for example, Patent Document 1).

  As another example, in detection of loss of a sheet which is nipped and conveyed by a belt, a fixed roller having a fixed shaft and a movable roller having a support structure capable of moving up and down are disposed in the conveyance path as a pair. There is a method of detecting the displacement amount of the movable roller when the sheet passes between the both rollers as thickness, and detecting a partial change in thickness as a defect. Furthermore, in order to detect foreign matter in the width direction of the sheet, a plurality of roller pairs are arranged in parallel in the direction orthogonal to the transport direction to detect the distribution of thickness, and an abnormal thickness portion is detected from thickness change in the width direction. There is a method to detect as foreign object.

  In the OVD sticking machine, in which at least two or more sheets transported by the stream feeder method are transported to the OVD pasting unit in a state where the sheets are continuously overlapped on the transport table, the sheet flow direction of the transport table In the vicinity of the left and right end portions of the sheet and at a position substantially perpendicular to the sheet conveyed in the continuously overlapping state, the loss state of the left and right front end portions and the left and right rear end portions of the sheet is At least provided with detection means for detecting, determination means for comparing and determining the sheet loss state detected by the detection means with a predetermined threshold, and control means for controlling the OVD sticking machine according to the result obtained by the determination means An OVD sticking machine defect state detection device is disclosed. Examples of detection means in the present technology include an optical sensor, an ultrasonic sensor, and a contact sensor (see, for example, Patent Document 2).

Japanese Patent Application Publication No. 07-112851 JP, 2010-149940, A

  However, the technique of Patent Document 1 prints a detection mark in the margin of the sheet and measures the reflectance of the detection unit by an optical sensor, so that an erroneous determination is made when the printing density is light or thick. there is a possibility. In addition, for banknotes and the like with many printing colors, there is a problem that it is difficult to secure a space for printing a detection mark because a printing header such as a color patch is given to the margin portion.

  Also, in the method of detecting the thickness of paper sheets by the displacement of the movable roller, the followability to the thickness change is to detect a defect in which a piece of paper or the like is mixed between the sheets conveyed by the stream feeder method. The problem is that there is a problem in adopting this method for a stream feeder type defect detection device.

  Further, in the technology of Patent Document 2, in the OVD sticking machine, the vicinity of the left and right ends of the sheet and the sheet being conveyed in the continuously overlapped state are substantially perpendicular to the sheet flow direction of the conveyance table. It is essential to install a detection means at a position, and it is intended to detect an angular break in which a corner of the sheet is broken. However, since it is not known in which part on the sheet the defect such as a piece of paper is mixed, a problem remains in adopting the present apparatus in the sheet conveying unit of the printing press.

  An object of the present invention is to solve the above-mentioned problems, and provide a defect detection device for detecting defects such as a sheet of paper attached to a sheet or an angular break of a sheet by ultrasonic waves in a sheet conveyance unit of a printing machine. Do.

  The defect detection device for a printing press according to the present invention has a transport unit having a transport belt for transporting to a printing unit in a state where the supplied sheets are continuously overlapped by a stream feeder method, and from one side of the sheet A detection unit for acquiring a detection waveform of the amount of ultrasonic waves received by an ultrasonic detection mechanism having a pair of transmission means for transmitting an acoustic wave and reception means for receiving an ultrasonic wave from the other surface of the sheet; And a control unit configured of a storage unit for storing a reference waveform of the sound quantity, and a comparison determination unit for comparing the detected waveform with the reference waveform to determine whether the waveform is correct or not. .

  The defect detection device for a printing press according to the present invention further includes a reference waveform stored in advance in the storage unit as a result of determination by the display unit and / or the comparison determination unit for displaying the result determined by the comparison determination unit. When it judges, it is characterized by having an alarm part for emitting an alarm.

  The defect detection device according to the present invention can detect foreign matter such as a piece of paper before the sheet is transported to the printing unit, so that it is possible to prevent deprinting of the design portion due to the foreign matter and suppress generation of defective products and achieve stable quality control. Realization is possible.

  In the case of printout due to foreign matter etc., the workload for inspection for finding foreign matter, judgment of acceptance / rejection of the product concerned and determination of related products, and paper fragments etc. on the surface of printing plate and impression cylinder Since generation | occurrence | production of the various expenses accompanying each replacement | exchange generate | occur | produced when a foreign material contacts and a dent arises can be prevented, the effect of cost control can be anticipated.

  Furthermore, it can be expected to detect a defect on the printing surface of the sheet which could not be found by the defect detection device such as a corner break which has been equipped until now.

The schematic diagram of the defect | deletion detection apparatus in one embodiment of this invention is shown. The schematic of the ultrasonic detection mechanism in the embodiment is shown. The block diagram of the defect | deletion detection apparatus in the embodiment is shown. The flowchart of the defect | deletion detection in the embodiment is shown. The relationship between the detection waveform in the embodiment and a reference waveform is shown. The abnormal waveform of the detection waveform in the embodiment is shown. The schematic of the sheet | seat holding means in the embodiment is shown. The schematic of the sheet supply means in the embodiment is shown.

  An embodiment for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments to be described below, and includes various other embodiments within the scope of the technical idea in the claims.

  FIG. 1 shows a schematic view of a defect detection device according to the present invention. The defect detection device (1) is installed in front of the printing unit in a printing machine (not shown), and conveys the sheet (2) supplied from the supply unit of the printing machine in the direction S1 in the drawing The ultrasonic wave detection mechanism (3) for detecting a defect of the sheet (2) is provided on the conveyance table (6) to be conveyed to the lower side.

  FIG. 2 shows a schematic view of the ultrasonic detection mechanism (3). FIG. 2 (a) illustrates the ultrasonic detection mechanism (3) as viewed from the side of the sheet (2), and has transmission means (4) for transmitting ultrasonic waves to one side of the sheet (2). And the receiving means (5) for receiving the ultrasonic waves transmitted from the transmitting means (4) on the other side of the sheet (2).

  The ultrasonic detection mechanism (3) has a transmitting means (4) and a receiving means (5) as a pair, and as shown in FIG. 2 (b), when viewed from the front of the defect detecting device (1) It is desirable to arrange a plurality of units in close proximity to one another and evenly.

  In the present invention, the loss of the sheet (2) refers to a state in which foreign matter such as a piece of paper is mixed in the sheet (2), or a part of the sheet (2) is missing due to angular breakage or the like. It means the state.

  FIG. 3 shows a block diagram of the defect detection device in the present invention.

  The defect detection device (1) may be configured of a transport unit (101) and a control unit (102), and may further have a display unit (106) and an alarm unit (107). Further, the control unit (102) includes a detection unit (103), a storage unit (104), and a comparison determination unit (105). Each of these will be described below.

  The transport unit (101) is configured of a transport table (6) for transporting the sheet (2), and in the supply unit, in a state where the sheets (2) supplied by the stream feeder method are continuously overlapped. , And a unit for conveying to the printing unit.

  The detection unit (103), which is one of the control units (102), includes a transmission unit (4) for transmitting an ultrasonic wave, and a reception unit (5) for receiving the transmitted ultrasonic wave. 5) is a part which graphs the amount of ultrasonic waves received and makes it a detection waveform.

  A storage unit (104), which is one of the control units (102), is a unit that stores in advance a reference waveform of a normal value.

  The comparison / determination unit (105), which is one of the control units (102), compares the detected waveform graphed by the detection unit (103) with the reference waveform stored in advance in the storage unit (104). Is a unit that determines whether the Comparison of waveforms referred to here means, for example, pattern matching, but the present invention is not limited to this as long as it is means for comparing waveforms.

  The display unit (106) displays the result determined by the comparison / determination unit (105), and displays an abnormality so that the operator's eyes can confirm if it deviates from the criteria stored in advance in the storage unit (104). Is the unit that The means for displaying these results may be any means that can be confirmed by the operator, such as printing by a monitor of a personal computer or a printer.

  The alarm unit (107) is a unit that issues an alarm so that the operator's ear can confirm if it deviates from the criteria stored in advance in the storage unit (104) as a result of determination by the comparison determination unit (105). .

  FIG. 4 shows a flowchart of defect detection in the present invention. However, this flowchart shows only one cycle.

  First, the sheet (2) stacked in the supply unit (not shown) is supplied to the transport unit (101) by the stream feeder method for continuously supplying, and the sheet (2) is supplied from the supply unit in the transport unit (101). The transported sheet (2) is transported onto the transport table (6) (STEP 1).

  Next, in the detection unit (103), an ultrasonic wave is transmitted from the transmission means (4), the transmitted ultrasonic wave is received by the reception means (5) (STEP 2), and a waveform is detected based on the received ultrasonic wave. To do (STEP 3). The detected waveform is taken as a detected waveform.

  Next, in the comparison / determination unit (105), the detected waveform detected by the detection unit (103) and the reference waveform stored in advance in the storage unit (104) are compared (for example, pattern matching) (STEP 4).

  In the comparison / determination unit (105), as a result of comparison, if the detected waveform and the reference waveform match, the sheet (2) is conveyed to the printing unit (STEP 5), and if not, conveyance of the sheet in the conveyance unit (101) Stop (STEP 5 ').

  If the comparison result does not match in the comparison / determination unit (105), the display unit (106) displays an abnormality (STEP 6 ').

  Furthermore, if the comparison result does not match in the comparison / determination unit (105), an alarm is issued in the alarm unit (107) (STEP 6 ′ ′).

  Note that the abnormality display in the display unit (106) and the alarm in the alarm unit (107) are not essential parts, and it can be determined according to the work situation whether or not to accompany.

  The above flow is one step. Although not shown in the flow, in actual production, all steps are repeatedly performed, and at the end of the operation, the conveyance unit (101) is ended by stopping conveyance of the sheet (2).

  FIG. 5 shows the relationship between the reference waveform and the detected waveform.

  FIG. 5A shows an example of the reference waveform, in which ultrasonic waves are attenuated by the supplied sheet (2), and the sheets are continuously overlapped on the transport table by the stream feeder method. Thus, the sheet (2) has a waveform in which one part and two parts are continuous.

  FIG. 5 (b) is an example of a detection waveform in the normal state, and the comparison / determination unit (105) is judged to be coincident as a result of comparison with the reference waveform (a).

  FIG. 6 (a) is an example of a detection waveform of defect detection, in which a part of the supplied sheet (2) has a defect and there is no attenuation of ultrasonic waves, the reference in the comparison / determination unit (105) As a result of comparison with the waveform (a), it is determined that they do not match.

  FIG. 6 (b) is an example of a detection waveform of foreign matter detection, in which foreign matter is mixed in the supplied sheet (2), and since ultrasonic waves are attenuated from the number of sheets (2), comparison and judgment are made. In the part (105), as a result of comparison with the reference waveform (a), it is judged as non-coincidence.

  In pattern matching between the reference waveform and the detection waveform in the comparison / determination unit (105), even if not completely coincident, it is possible to set an allowable range in the reference waveform in order to make it match if it is within the allowable range. .

  The sheet (2) supplied by the stream feeder method is in a state of being continuously overlapped on the conveyance table (6), and when there is a void or the like in the overlapping portion, noise such as attenuating ultrasonic waves is generated. The following measures are also one of the methods because there is a possibility of connection.

  FIG. 7 shows an example of a means for pressing the upper portion of the overlapped sheets (2) as a measure against voids, which is a sheet pressing means (7) for pressing the sheet (2) with a brush or air, etc. 3) installed on the side of the supply unit, the side of the printing unit, or both.

  FIG. 8 shows an example of a means for adsorbing the lower portion of the overlapped sheets (2) as a measure against voids, which is a sheet adsorbing means (8) for adsorbing the sheet (2) by air or static electricity, etc. The mechanism (3) is installed on the supply unit side, the printing unit side, or both.

  Only one of the sheet holding means (7) and the sheet suction means (8) may be provided, or both may be provided.

1 defect detection device 2 sheet 3 ultrasonic wave detection mechanism (detection unit)
Reference Signs List 4 transmission means 5 reception means 6 conveyance table 7 sheet pressing means 8 sheet suction means 101 conveyance unit 102 control unit 103 detection unit 104 storage unit 105 comparison determination unit 106 display unit 107 alarm unit

Claims (2)

In the printing machine defect detection device,
The defect detection device includes a conveyance unit having a conveyance belt for conveying the supplied sheets to the printing unit in a state where the supplied sheets are continuously overlapped by the stream feeder method;
The detected waveform of the amount of ultrasonic waves received by the ultrasonic detection mechanism comprising a pair of transmitting means for transmitting ultrasonic waves from one side of the sheet and receiving means for receiving the ultrasonic waves from the other side of the sheet A control unit comprising a detection unit for acquisition, a storage unit for storing a reference waveform of normal ultrasound amount in advance, and a comparison / determination unit for comparing the detected waveform with the reference waveform to determine whether it is correct or not When,
A defect detection device characterized by comprising:   The defect detection apparatus further determines that the reference waveform stored in the storage unit is not identical as a result of determination by the display unit for displaying the result determined by the comparison determination unit and / or the comparison determination unit. 2. The defect detection device according to claim 1, further comprising an alarm unit for emitting an alarm.

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