JPH06194205A - Method for inspecting volume of plastic bottle and bottle inspecting device for executing method thereof - Google Patents

Abstract

PURPOSE: To precisely measure the volumes of bottles by measuring the height of at least one bottle. CONSTITUTION: The height and the volume of, for example, polyethylene terephthalate(PET)-bottles in a prescribed shape have an extremely strict correlation and consequently, the volume of a bottle 1 can be estimated at good precision from the height of the bottle. A transmitter 4 sends out band like laser beam 5 and a receiver 6 receives the beam. In this case, the upper end 3 of the bottle 1 shuts the band-like laser beam 5 from the lower side of the laser beam 5. The higher the bottle 1 is, the more the bottle 1 enters deeply in the laser band and the more the light quantity to be received is lessened. In the case the height of the bottle 1 is short, the bottle 1 does not so much enter in the laser band and the light quantity to be received is increased. In this way, the height of bottles can be highly precisely measured.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for inspecting plastic return bottles, in particular PET bottles, for volume. Furthermore, the invention relates to a bottle inspection machine for carrying out the method.

[0002]

2. Description of the Related Art Plastic bottles (this is especially P
It is known to test ET (polyethylene terephthalate) bottles) on each return cycle. The bottles are inspected for scratches and cleanliness.

It would be desirable in some cases to extend the inspection to simple volumetric inspections, especially PET.
Made bottles are not volume stable. Therefore, it may happen that the PET-bin no longer has the required target volume before it has reached its pass life (about 25 fills), which can be a problem especially during filling.

[0004]

SUMMARY OF THE INVENTION The object of the invention is to carry out the desired inspection process quickly in a simple manner and with sufficient accuracy.

[0005]

The method of the present invention for solving the above-mentioned problems is to measure at least the linear dimension of a bottle.

[0006]

Surprisingly, plastic bottles, especially PET
-In bottles it has been shown that the volume of the bottle can be measured with sufficient precision by measuring the linear bottle size.
Measurement of linear dimensions is very easily possible even in bottles that are transported at high speeds in the inspection machine.

The height of the bottle is preferably measured. PET
-In the bottle, it was revealed that the PET-bin contracted especially in height, mainly due to this resulting in a volume reduction. Furthermore, the height dimension can be measured particularly easily, as described below.

The bottle inspection machine according to the invention comprises a measuring device for linear dimensions.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Only the head region 2 of a PET-bin 1 is shown in FIG. The transmitter 4 transmits a band-shaped laser beam 5, which is received by a receiver 6. A suitable transmitter / receiver device including the associated receiver amplifier is manufactured, for example, by FimaKeyence (Osaka, Japan) under the type designation LX2. The receiving amplifier can, for example, tell if the received laser power exceeds or falls below a certain limit value, or gives an analog voltage proportional to the received light power, which analog voltage is further processed. be able to.

In the arrangement shown, the amount of light received depends on the height of the bin, since the upper edge 3 of the bin blocks the band-shaped laser beam from below this laser beam. The higher the height of the bin, the deeper it penetrates into the light band or the less light it receives. When the height of the bin is small, the bin does not penetrate much into the light band and the amount of light received is large. In this way the height of the bottle is measured with an accuracy of about 0.1 mm. The height measurement above is because the height and volume are very closely correlated for a given shape of PET-bin and therefore the volume of the bin can be inferred with good accuracy from the height of the bin. Gives a simple and quick possibility of volume checking. In this case it is usually only necessary to measure below a certain lower limit on the height of the bin (upper limit for the amount of light received), since it is usually important for the inspection to be below the target volume. Because it is. Instead of the height of the bottle, other linear dimensions that correlate sufficiently closely with the type of bottle inspected may be measured. For example, the height from the bottom of the collar 3 or the diameter of the bottle may be measured, as appropriate as a measure of volume change for a particular type of bottle.

In the above height measurement, the bottle starts at the bottom or is transported by the bottom, and the distance between the bottom and the measuring device 4, 5, 6 is known and fixed. . It is usually employed in conveyors of inspection machines, such as merry-go-round conveyors or conveyor belts. If the measurement is made in such a way that the position of the bin is not strictly defined, two measuring devices can be arranged, in which case one measuring device detects the upper edge of the bin (see FIG. And other measuring devices detect the bottom edge of the bin. From the two light quantities or output signals of the measuring device, the height of the bin or the maintenance of its target volume can be measured.

[0012] Advantageously, the measurement of the linear dimensions of the abovementioned bins is carried out on an inspection machine. The measuring devices can be arranged in different ways along the transport path. Multiple measuring devices may be provided to test multiple bins separately. According to the invention, the measurement result can be used for volume inspection only if the inspection machine already determines the measurement of the height of the bottle as a volume measurement with sufficient accuracy for other reasons.

The measurement of linear dimensions can also be carried out, for example, in a filling station, apart from the inspection machine along the bin transport path.

Furthermore, it is advantageous if the discharge device is connected after the height or the volume measurement. The ejection device is responsive to the measurement result, and the measured bottle that is too small is removed from the transport path,
Therefore, it is released from the circulatory system.

[Brief description of drawings]

FIG. 1 is a schematic view of a measuring device for measuring the height of a bottle.

[Explanation of symbols]

 1 bin 2 head region 3 upper edge 4 transmitter 5 laser beam 6 receiver

Claims (9)

[Claims] 1. A method for inspecting a plastic go-through bottle for volume, comprising measuring at least one linear dimension of the bottle. 2. The method of claim 1, wherein the height of the bottle is measured. 3. Comparing the measured linear dimension with a target value,
And remove from the circulation through the bottles below this target value,
The method according to claim 1 or 2. 4. The method according to claim 1, wherein the linear dimension is measured using an optical measuring method. 5. The method of claim 4, wherein the bin is guided through a partially widened laser beam and the attenuation of the laser beam by the passed bin portion is measured and taken as a reference for linear dimensions. 6. The method according to claim 5, wherein the upper edge of the bottle is guided from below into a laser light band which is vertically expanded, and the height of the bottle is measured. 7. A bottle inspection machine for carrying out the method according to any one of claims 1 to 6, characterized in that it comprises at least one transport device for guiding the bottles through the inspection machine. At least one measuring device is provided along the transport path at a location, and the linear dimension of each bin transported through the measuring device can be measured by the measuring device. 8. The measuring device comprises a laser light transmitter for generating a laser beam spread in a band, a laser light receiver positioned away from the laser light transmitter, and an evaluation device. 8. A bin inspection machine according to claim 7, adapted to measure the attenuation of a laser beam by a bin which is guided through the laser beam with an optical receiver. 9. The bottle inspection machine according to claim 8, wherein the inspection machine comprises an evaluation device cooperating with an evaluation circuit for eliminating bins which do not reach the linear target dimension.