JPH0529862B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a leak detection device for a sealed container made of flexible material such as a plastic bottle.

Conventional technology Leakage from sealed containers made of flexible materials, such as plastic bottles filled with liquids such as liquid detergent, oil, and drinking water, is caused by minute holes caused by poor sealing or molding of the seal part of the cap, etc. Due to these reasons, leakage inspections are generally performed in filling and sealing lines. For example, as a device for automatically detecting leakage from sealed containers,
-79579, JP-A-59-163532, JP-A-49-98296, JP-A-59-15832, and JP-A-59-157532 are known. ing. These conventional devices, for example, press and deform the body of a sealed container conveyed by a turret, measure the thickness of the body of the container after a certain period of time, and
The presence or absence of liquid leakage is determined based on the measurement results, and the reaction force or amount of deformation at that time is measured by pressing the body of the container, and the internal pressure of the container is determined based on the correlation between the amount of deformation and the internal pressure. It can be broadly classified into those that do.

Problems to be Solved by the Invention Among the above-mentioned conventional leakage testing devices for sealed containers, those that measure the internal pressure by the reaction force or displacement when the body is pressed are not suitable for small leaks or when the line is operating at high speed. In this case, the amount of air and liquid that leaks from the leakage part when pressed is small, so the difference in displacement and internal pressure between a normal container and a defective container is small, making it difficult to accurately detect minute leaks. It was hot. In addition, the method that measures the body thickness after a certain period of time after pressing measures the body thickness of the container during transportation, so measurement errors are likely to occur due to vibrations and posture of the container, and minute errors may occur. It was difficult to accurately detect displacement. Therefore, it has been difficult to increase the speed of these devices.

The present invention was devised to solve the above-mentioned problems of the prior art, and in particular, it is capable of accurately detecting even minute leaks in sealed containers made of soft materials and capable of detecting leaks in sealed containers at high speed. The purpose is to provide an inspection device.

Means for Solving the Problems In order to achieve the above object, the leak detection device for a sealed container of the present invention is arranged such that the leakage detection device for a sealed container of the present invention is arranged such that the leakage detection device for a sealed container faces each other along both sides of a sealed container conveyance path at an interval slightly narrower than the thickness of the sealed container body. a pair of body side holding belts which are arranged along the container body side holding belts to sandwich and transport the body side of the sealed container; a compression unit having at least a pair of pressure rolls for pressing the container body, which is disposed downstream from the compression unit and presses the body of the container held and conveyed by the container body side holding belt with a constant pressure by a displacement means; a displacement detection pressure roller on the displacement side that is displaceably provided so as to be displaceable; a fixed side displacement detection pressure roller that is disposed opposite to the displacement detection pressure roller with the container conveyance path in between; The present invention employs a configuration characterized by comprising a measuring section having a displacement meter that measures the amount of displacement of the displacement-detecting pressure roller on the displacement side.

Function The sealed container filled with liquid is conveyed from both sides with the body side held by belts holding the body side, and is conveyed by a pair of press rolls arranged at a distance slightly narrower than the width of the body of the sealed container. By passing between
The body is pressed by the pressure roll. As a result, the pressure inside the sealed container increases, and if there is a sealing failure, the air and liquid content in the head space will leak from the defective location, reducing the internal pressure and deforming the sealed container into a concave state at the pressed location. However, when the plastic bottle passes through the pressure roll section and the pressure is released, the dents gradually recover in the case of plastic bottles, but the dents do not completely recover until the bottle reaches the measurement section and the dents remain. If there is no leakage point, the pressure is released and at the same time it returns to its original shape and reaches the measurement point.

When the sealed container whose body has been pressed by the compression section reaches the measurement section, the pressing means presses the side of the sealed container again with a constant pressure. At this time, in the case of a defective container with a leakage point, the displacement amount of the pressing means becomes large because the dent created by the decrease in internal pressure in the compression part has not been recovered. On the other hand, if there is no leakage point, the resistance to pressing is strong and the amount of denting is small, so the amount of displacement of the pressing means is also small. Therefore, by detecting the amount of displacement of the pressing means with the displacement detector, it is possible to determine whether there is a leak in the sealed container. In particular, in the present invention,
After the compression part is pressed, the measurement part is further pressed with a constant pressure and the amount of displacement is detected, so even if the line speed is high, minute leaks can be reliably detected. In addition, compared to the conventional method in which the degree of recovery of the object pressed in the compression part is simply detected by the measurement part, the conveyor There is little influence from vibrations, etc., and displacement can be detected reliably.
Therefore, compared to the conventional method, it is possible to improve the discrimination accuracy and increase the speed.

Moreover, in the present invention, since the sealed container is conveyed without being rotated while being held between the body side holding belts, the compressing section and the measuring section can press the same location, and the container has a non-circular body. Accurate displacement can be measured even in a sealed container.
Furthermore, since the pressing of the container body in the compression section and the measurement section is performed by a pair of rotatable pressing rolls that are placed opposite to each other across the sealed container conveyance path, the sealed container is conveyed during pressing. Since there is little resistance applied in the direction, it can be pressed smoothly, and even if it is pressed little by little from both sides, it can be largely deformed as a whole, so the impact on the container body can be reduced and leakage can be measured accurately.

Embodiment FIG. 1 shows an embodiment of a leak detection device for a sealed container according to the present invention. . In the figure, reference numeral 1 denotes a main body of the detection device, which is installed on a pole 2 erected next to a container transport conveyor 40 of a liquid content filling line so as to be adjustable up and down.

3, 3' and 4, 4' are side-holding round belts for holding and conveying the body of the sealed container during leakage detection. The round belts 3, 3', 4, 4' are connected to drive pulleys 7, which are supported by side frames 35, 36 provided on the main body frame 5 so that their intervals can be adjusted.
12 and the driven pulleys 6 and 11, and are provided in pairs, upper and lower, along both sides of the sealed container transport conveyor. A plurality of guide pulleys 8 to 10 and 13 to 15 are provided between the driving pulley and the driven pulley, and these guide pulleys control the distance between the round belts on both sides to convey the sealed container. The trunk side holding belts are guided at slightly narrower intervals due to the thickness of the belt. The drive side pulleys 7, 7', 12, 12' are connected to the motor 16.
As shown in Fig. 4, the side frames are rotatably driven via a drive shaft 18 whose middle part is connected by a spline shaft joint 17, so that the interval between the side frames can be adjusted, and the side frame holding round belt is rotated in synchronization with the conveyor. I'm letting you do it.

A compression section 19 is provided along the body side holding belt to press the body of a sealed container that is conveyed while holding the body between the body side holding belts, and a measuring section 31 is provided following the compression section. ing.

The compression section 19 consists of a pair of pressure rolls (only one of the pressure rolls 22 is shown in FIG. ), and a pair of pressure rolls (not shown) provided on the shafts of the guide pulleys 9, 14 in the same plane as the round belts 3, 3' and 4, 4 so as to press the sealed container. It consists of two sets of pressure rolls. In addition, in this example device, there are two pressure rolls.
Although a set of press rolls is provided, one or more press rolls can be appropriately selected depending on the conveyance speed of the sealed container.

The measurement unit 31 is provided following the compression unit, and presses the sealed container that is conveyed after being pressed at the side by the compression unit again with a constant pressure, and detects leakage of the sealed container based on the displacement at that time. This is the place to do it. The measuring section 31 is composed of a pressing means for pressing the body of the sealed container and a displacement detecting means for detecting displacement of the pressing means. The pressing means is attached to the side frame 3, as shown in a sectional view in FIG.
Press roll 2 for displacement detection supported by 5, 36
One of the pressure rolls 25 of 4 and 25 is installed on a sliding frame 29 fixed to the cylinder rod 27 of an air cylinder 26 which is a displacement means, and is projected into the sealed container transport path by the operation of the air cylinder 26. It is configured as follows. The displacement detecting means includes a displacement detector 30 for detecting the displacement of the piston rod 27, and in the illustrated embodiment, a differential displacement transducer is employed. Note that 28 in the figure is a guide frame that guides the sliding frame 29.

The sealed container leak detection device of this embodiment is constructed as described above, and the sealed container leak test is performed as follows.

The sealed container filled with liquid and sealed is conveyed by a conveyor 40, and when it reaches the inspection position, it is conveyed with the body side portions held between both sides by body side holding belts. In the compression section 19, the body is pressed by the press rolls by passing between a pair of press rolls arranged at an interval slightly narrower than the width of the body of the sealed container. As a result, the pressure inside the sealed container increases, and if the lid is not completely tightened or there is a microscopic hole in the sealed container, the air in the head space or the liquid inside may leak from the defective location. , the sealed container depressurizes and deforms into a concave shape at the pressed location. When the plastic bottle passes through the press roll and the pressure is released, the dent will gradually recover, but if there is no leakage area, the bottle will return to its original shape as soon as the pressure is released. After passing between the first set of pressure rolls, the same location is pressed again by the second set of pressure rolls after a predetermined period of time. A container with a leakage point does not return to its original shape even after passing through the compression section and reaches the measurement section 31 with a dent remaining, but a normal container without a leakage point is almost completely restored to its current state and measured. reach the department.

When the sealed container whose body has been pressed in the compression section reaches the measurement section, the air cylinder 26 is operating at a constant pressure, and the deformation detection press roll 25 presses the side of the sealed container again with a constant pressure. . At that time, in the case of a defective can with leakage points, the dent made by the pressing part has not recovered, so the cylinder rod 2
7 becomes larger. On the other hand, if there are no leakage points, the resistance to pressure is strong and the amount of denting is small, so the amount of displacement of the cylinder is also small. Therefore, by detecting the amount of displacement of the cylinder rod with a displacement detector, it is possible to determine whether there is a leak in the sealed container. The amount of displacement detected by the displacement detector is
The CPU compares it with the set value to determine pass/fail, and if the displacement is outside the allowable range, a reject signal is issued. When the reject signal is issued, a rejector (not shown) operates to discharge the poorly sealed container from the conveyor to the outside of the line.

In general, if there is a small leak such as a small hole, and the line speed is high, the air inside will not easily leak to the outside with one press, and the restoration after the press is released will be quick and accurate in detecting a sealing failure. However, in this example, multiple sets of pressure rolls are provided,
Since the same spot is pressed multiple times, even minute leaks can be reliably detected.

When inspecting sealed containers with different body diameters, body thicknesses, and heights, adjust the distance between the side frames 35 and 36, and move the detector body 1 up and down along the pole 2 to adjust its height position. This makes it easy to apply. In this way, the device of this embodiment
Even if the type of sealed container is different, it can be easily adjusted.
It can be easily applied to filling and sealing lines for various sealed containers.

Note that the present invention is not limited to the above embodiments,
Various design changes are possible within the scope of the above technical concept. For example, as the pressing means of the measuring section, in the above embodiment, the pressing roll was operated by a cylinder at a constant pressure, but the pressing roll may be pressed by a spring having a constant spring pressure.

Effects The leak detection device for a sealed container of the present invention is configured as described above, and after a certain amount of pressure is applied in the compression part, the measurement part is further pressed with a certain pressure to detect the amount of displacement. Even at high line speeds, minute leaks can be detected reliably. In addition, compared to the conventional method in which the degree of recovery of the object pressed by the pressing part is simply detected by the measuring part, this method detects the displacement when the object is pressed again with a constant pressure. There is little influence from vibrations, etc., and displacement can be detected reliably. Moreover, since the sealed container is conveyed without being rotated while being held between the body side holding belts, the compressing section and the measuring section can press the same location, and even a sealed container with a non-circular body can be transported without being rotated. It is possible to accurately measure the amount of displacement. Furthermore, since the pressing of the container body in the compression section and the measurement section is performed by a pair of rotatable pressing rolls that are placed opposite to each other across the sealed container conveyance path, the sealed container is conveyed during pressing. Since there is little resistance in the direction, it can be pressed smoothly, and even if it is pressed slightly from both sides, it can be deformed greatly as a whole.
Since the impact on the container body is small, the container is not damaged, and in combination with the clamping by the body side holding belt, leaks can be detected accurately even at high speeds. Therefore, the present invention has the remarkable effect of being able to accurately and quickly test for leaks in sealed containers made of flexible materials, compared to conventional methods.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention.
2 is a sectional view taken along line BB in FIG. 1, FIG. 3 is a sectional view taken along line C-C in FIG. 1, and FIG. 4 is a sectional view taken along line AA in FIG. 1. 1...Detection device main body, 2...Pole, 3, 3',
4, 4'... Side holding round belt, 5... Body frame, 6, 11... Driven side pulley, 7, 12...
... Drive side pulley, 8-10, 13-15 ... Guide pulley, 16 ... Motor, 19 ... Compression section, 20 ... Guide pulley shaft, 22 ... Press roll, 24, 25 ... Press for displacement detection roll, 26
...Air cylinder, 27...Cylinder rod, 30...Displacement meter, 31...Measuring section, 35,3
6... Side frame, 40... Container transport conveyor, 41... Container.

Claims (1)

[Claims] 1 arranged oppositely along both sides of the sealed container transport path at an interval slightly narrower than the thickness of the sealed container body,
A pair of body side holding belts that sandwich and convey the body side of the sealed container, which are arranged along the container body side holding belt to face each other across the sealed container transport path, and press the body side of the sealed container. a compression unit having at least a pair of pressure rolls, which is disposed downstream of the compression unit and is displaced so as to press the body of the container held and conveyed by the container body side holding belt with a constant pressure by a displacement means; a pressure roller for displacement detection on the displacement side that is provided so as to be able to move; a pressure roller for displacement detection on the fixed side that is provided opposite to the pressure roller for displacement detection across the container conveyance path; 1. A leakage detection device for a sealed container, comprising a measurement section having a displacement meter that measures the amount of displacement of a detection pressure roller.