JPH048326Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a press mark detection device that can be applied to corrugating machines.

(Prior Art) Press marks on cardboard sheets not only cause problems in appearance, such as impairing printing performance, but also pose problems in terms of strength. Here, the process of generating press marks will be explained with reference to FIG. 6, which is a configuration diagram of the main rolls of a conventionally well-known general single facer for manufacturing single-stage sheets in a corrugating machine. Sheet 15 which becomes the core of the cardboard between
is formed into a corrugated shape, and glue is applied by a glue roll 14 to the top of the formed corrugated sheet. The pasted corrugated sheet is pressure bonded to the liner 16 between the lower roll 12 and the pressure roll 13. When the bonded single-tiered sheet 17 is viewed from the liner side, as shown in FIG. 5, there are streaks running in the bonded area between the liner and the corrugated sheet, which are called press marks 10.

This press mark 10, which is approximately 1 mm wide, is subjected to heat and pressure by the lower roll 12 and pressure roll 13, so it can be seen as a change in color tone, which is a brown streak, but it has become more glossy. It can also be interpreted as a change in gloss.
These press marks are constantly checked by operators during the corrugated board manufacturing process as a guide to the bonding state of the corrugated sheet serving as the core and the liner. If the press mark is too strong, it not only gives an unfavorable appearance, but also causes problems such as cracking of the liner and a decrease in strength.On the other hand, if the press mark is too weak, the adhesion strength is insufficient, resulting in poor lamination. There are problems that arise. This is an important element in terms of the quality of cardboard sheets, but in the past, operators visually inspected and judged the cardboard sheets after they were completed. However, visual inspection has the disadvantage that quality is difficult to stabilize because there are many variations depending on the individuality and skill of the operator. Moreover, inspection was difficult due to the number of operators, machine speed, etc.

(Problems to be solved by the invention) This invention solves the problems that the conventional visual inspection has, such as difficulty in achieving stable quality and difficulty in inspection, and can be incorporated into a line where corrugated cardboard sheets are continuously supplied. This problem is solved by a press mark detection device that enables highly accurate measurement.

(Means for Solving the Problems) Therefore, the present invention includes a sheet conveying means for conveying a corrugated cardboard sheet in a direction perpendicular to the press mark, a slit disposed perpendicular to the conveying direction of the sheet, and a sheet a light source that irradiates incident light over the transport width, and a photodetector that is disposed at a specular reflection position with the light source and receives reflected light that forms the same angle as the incident light with respect to the transport direction, The photodetector is designed to continuously measure the strength of press marks in-line by receiving reflected light across the width of the slit, and this is a means to solve the problem. It is something.

(Function) When the slit light is between the press marks,
Since only the gloss of the sheet is measured, the gloss is the weakest, and as the sheet travels and the slit light comes to the position of the press mark, the intensity of the gloss increases.
When the slit light covers a part of the press mark, the intensity is intermediate between the two, and it is therefore possible to detect gloss as a signal that repeats strength and weakness as the sheet travels. Since the strength of the gloss is proportional to the strength of the press mark, it is possible to know the strength of the press mark by measuring the strength of the gloss, that is, the amplitude of the fluctuating signal.

(Embodiments) The embodiments of the present invention will be described below with reference to the drawings. The drawings show the embodiments of the present invention. When detecting press marks on a cardboard sheet using light, they appear as dark streaks (scorched paper marks) when diffusely reflected light is detected, but when viewed under specularly reflected light, they appear as brightly glowing streaks. This is because the surface of the sheet is smoothed when pressure bonding is performed between the pressure roll and the lower roll of the single facer. When comparing the two methods, it was found through experiments that the detection sensitivity was higher when specularly reflected light was measured. Figure 3 shows an example of measuring specularly reflected light using a CCD line sensor camera. As can be seen from this example, press marks do not necessarily have uniform strength in the sheet width direction.

Next, referring to FIG. 1, reference numeral 1 denotes a corrugated cardboard sheet, which is conveyed on guide rolls 2 in the direction of the arrow. Reference numeral 10 denotes a press mark, which is formed in a striped manner in a direction perpendicular to the conveyance direction indicated by the arrow. Reference numeral 3 denotes a light source whose incident light is irradiated onto the press mark 10 on the sheet 1 as shown by the dotted line in FIG. After passing through the entire width of the slit 4 arranged perpendicularly to the conveyance direction of the sheet 1, the light is focused by the condenser lens 5, and is then detected by the light source 3 and the photodetector 6 provided at the specular reflection position. Light is received.

Next, to briefly explain signal processing, the press mark signal is not output based on the absolute level of the intensity of the received light, but rather based on the light intensity of the non-press mark area. It is a relative measurement that calculates the strength of This makes it possible to perform highly accurate measurements without being affected by changes in lamp brightness, paper type, or reflection characteristics. In FIG. 1, 7 is an amplifier circuit, 8 is a press mark signal and reference signal detection circuit, and 9 is an arithmetic circuit.

(Effects of the invention) Since the present invention is configured as explained in detail above, it can be incorporated into a line where corrugated sheets are continuously supplied, there is no need for visual inspection, and the brightness of the lamp can be changed. It is not easily affected by changes in paper type, reflection characteristics, etc., and can automatically perform highly accurate measurements.

FIG. 4 shows the positional relationship between the slit light made by the slit and the press mark on the corrugated board sheet. By making the width of the slit light sufficiently shorter than the interval between press marks, the gloss of the press mark area and the area without press marks can be measured separately. As shown in the upper diagram of Figure 4, when the slit light is between the press marks, only the gloss of the sheet is measured, so the gloss is the weakest, and the sheet is traveling and the fourth
As the slit light approaches the press mark as shown in the middle of the figure, the intensity of the gloss increases. Also, when the slit light covers part of the press mark,
The intensity is intermediate between the two, and therefore, it is possible to detect gloss as a signal that repeats strength and weakness as the sheet travels, as shown in the right diagram of FIG. Since the strength of the gloss is proportional to the strength of the press mark, it is possible to know the strength of the press mark by measuring the strength of the gloss, that is, the amplitude of the fluctuating signal.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a press mark detection device showing an embodiment of the present invention, Fig. 2 is a side view showing a measurement state by the same device, and Fig. 3 is a state in which specularly reflected light is measured with a CCD licensor camera. 4 is an explanatory diagram showing the positional relationship between the slit light made by the slit in the present invention and the press marks on the sheet, FIG. 5 is an explanatory diagram showing the press marks, and FIG. 6 is the conventional one. FIG. 2 is a side sectional view of a corrugating machine. Explanation of the main parts of the diagram, 1...Cardboard sheet,
3...Light source, 4...Slit, 5...Condenser lens, 6...Photodetector, 10...Press mark.

Claims (1)

[Scope of utility model registration request] A sheet conveying means for conveying the corrugated cardboard sheet in a direction perpendicular to the press marks, a slit arranged perpendicular to the conveying direction of the sheet, a light source for irradiating incident light over the conveying width of the sheet, and the light source. and a photodetector that is disposed at a regular reflection position and receives reflected light that forms the same angle as the incident light with respect to the transport direction, and the photodetector receives the reflected light across the slit width. A press mark detection device characterized by continuously measuring the strength of a press mark inline.