APPARATUS FOR TESTING INTEGRITY OF SEAL OF

PLASTIC CONTAINER

Technical Field

[1] The present invention relates to an apparatus for testing the integrity of a seal of a plastic container filled with a liquid phase product, such as milk, beverages, dairy products or the like, or a plastic container filled with a nitrogen gas after filled with a solid product, such as cookies or the like, and, more particularly, to an apparatus for testing the integrity of a seal of a plastic container by applying predetermined pressure to the plastic container filled with a liquid phase product and testing repulsive pressure of the plastic container.

[2]

Background Art

[3] Korean Patent Application No. 10-2008-7008618 (filed on April 10, 2008) discloses methods for manufacturing unleaky sealed containers and leak testing apparatus.

[4] The leak testing apparatus is to test a leak of a sealed container which includes at least a first flexible wall area and a second flexible wall area having different flexibility characteristics. The leak testing apparatus comprises: a biasing arrangement for compressing the container under test; and a force detector applicable to the wall of the container under test and simultaneously generating an electric output signal, wherein an output of the force detector is operationally connected to a storing unit, an output of the storing unit is operationally connected to a first input of a comparator unit, a second input of the comparator unit is operationally connected to the output of the force detector, and wherein the biasing arrangement is positioned for biasing the first flexible area of the container and the force detector is arranged to operate with the second flexible area of the container.

[5] In the leak testing apparatus, when the biasing arrangement applies pressure to the first flexible area of the container, a foil-like cover sealing an opening of the container rises and then the detector detects the pressure applied when the foil-like cover rises, so that the seal condition is tested.

[6] However, in the case of a sealed container filled with the liquid phase product, for example, a plastic milk bottle currently produced in the Republic of Korea, a foil cover (sealing material) seals an opening of the sealed container when the opening of the sealed container is closed with a cap. Therefore, the leak testing apparatus disclosed in Korean Patent Application No. 10-2008-7008618 (filed on April 10, 2008) cannot be used for testing the seal condition of the sealed container produced in the Republic of Korea. [7]

Disclosure of Invention

Technical Problem

[8] Therefore, the present invention has been made to solve the above problems, and it is an aspect of the present invention to provide an apparatus for testing the integrity of a seal of a plastic container by applying predetermined pressure to the plastic container filled with a nitrogen gas or the like after filled with a solid product, such as cookies or the like, or to the plastic container filled with a liquid phase product, and testing repulsive pressure of the plastic container.

[9]

Technical Solution

[10] In accordance with the present invention, the above and other aspects can be accomplished by an apparatus for testing the integrity of a seal of a plastic container, characterized in that, when a sealed plastic container transported along a transportation conveyer passes between a first sensing unit and a second sensing unit, by arranging a space between the first sensing unit and the second sensing unit smaller than a diameter of a body of the plastic container, the body of the plastic container is compressed inwardly by the first sensing unit and the second sensing unit, repulsive pressure of the plastic container is relatively applied to the first sensing unit and the second sensing unit, the repulsive pressure of the plastic container is measured by the first sensing unit and the second sensing unit, then, measurement values measured by the first sensing unit and the second sensing unit are provided to a control unit, and a seal condition (good or bad) of the plastic container whether the measurement values are between the upper limit and the lower limit of a set value is determined by the control unit.

[11] The first sensing unit and the second sensing unit is a load cell.

[12] The control unit converts an analogue output value of the first sensing unit and the second sensing unit into a digital value to be received, reads an average value obtained by dividing a sum of the measurement value of the first sensing unit and the measurement value of the second sensing unit by two as an input value, and checks a transition of the input value (repulsive pressure) according to time, to determine the seal condition of the sealed plastic container as normal/good when a peak value of the input value is between the upper limit and lower limit of the set value and to determine the seal condition of the sealed plastic container as abnormal/bad when the peak value is over the upper limit of the set value or under the lower limit of the set value.

[13] The fist sensing unit is mounted onto a pressurized bearing secured to a first driving belt, among a number of bearings positioned inside the first driving belt, to measure the repulsive pressure of the plastic container applied to the pressurized bearing, and the second sensing unit is mounted onto a pressurized bearing secured to a second driving belt, among a number of bearings positioned inside the second driving belt, to measure the repulsive pressure of the plastic container applied to the pressurized bearing, wherein the pressurized bearing of the first driving belt and the pressurized bearing of the second driving belt are positioned to be opposite to each other at either side of the transportation conveyer, a first horizontal frame onto which the first driving belt is mounted and a second horizontal frame onto which the second driving belt is mounted are mounted onto a space control unit to control the space between the first driving belt and the second driving belt, and the space control unit is connected to an up/down movable panel of a height control unit to control a height position of the up/ down movable panel.

[14] The first driving belt and the second driving belt are rotated by their respective driving motors, and a rotation speed is controlled so that the plastic container transported by the transportation conveyer can pass the pressurized bearings without falling or being pushed backward.

[15] In the space control unit, a first support member is mounted onto the first horizontal frame, a second support member is mounted onto the second horizontal frame, a left screw unit of a screw shaft is mounted onto a nut member mounted onto the first support member, a right screw unit of the screw shaft is mounted onto a nut member mounted onto the second support member, a handle is mounted onto one end of the screw shaft, the first support member and the second support member are mounted onto two guide rods, movements of the first support member and the second support member are guided by the guide rods, and each one end of the two guide rods is connected to the up/down movable panel.

[16] In the height control unit, a vertical screw shaft is mounted onto a middle horizontal part of a base frame so as to be moved up/down by a handle, a top end of the vertical screw shaft is mounted onto the up/down movable panel, the guide rod is mounted onto the middle horizontal part and a top horizontal part of the base frame, and the up/ down movable panel is mounted onto the guide rod so that, when turning the handle in any one direction, the vertical screw shaft moves up and the up/down movable panel moves up along the guide rod and when turning the handle in the other direction, the vertical screw shaft moves down and the up/down movable panel moves down along the guide rod.

[17] The apparatus for testing the integrity of a seal of a plastic container further comprises: photo sensors onto which the first horizontal frame and the second horizontal frame are respectively mounted to sense the plastic container pulled between the first driving belt and the second driving belt; and a pushing unit mounted onto exits of the first driving belt and the second driving belt to push out the plastic container which seal condition is determined as bad by the control unit. [18] The apparatus for testing the integrity of a seal of a plastic container further comprises: a feeder screw unit to control the space between the plastic containers pulled into entrances of the first driving belt and the second driving belt.

Advantageous Effects

[19] In the apparatus for testing the integrity of a seal of a plastic container according to the present invention, the seal condition of the sealed plastic container is tested, the product which is defective in the seal condition is prevented from being sold by breaking a part in which the seal condition is finely imperfect, and seals of the plastic containers which are different in size are tested in one certain transportation conveyer line since the height control unit and the space control unit control the positions of the driving belts to be positioned corresponding to the size of the plastic container.

[20]

Brief Description of the Drawings

[21] These and other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

[22] FIG. 1 is a schematic view illustrating a constitutional concept of an apparatus for testing the integrity of a seal of a plastic container according to the present invention;

[23] FIG. 2 is a graph illustrating the characteristics of repulsive pressure of a plastic container, which is input into the apparatus for testing the integrity of a seal of a plastic container according to the present invention, versus time;

[24] FIG. 3 is a perspective view illustrating a main element of the apparatus for testing the integrity of a seal of a plastic container according to the present invention;

[25] FIG. 4 is a plan view illustrating the apparatus for testing the integrity of a seal of a plastic container according to the present invention; and

[26] FIG. 5 is a side view illustrating the apparatus for testing the integrity of a seal of a plastic container according to the present invention.

[27]

Mode for the Invention

[28] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[29] Referring to FIGS. 1 and 2, in an apparatus for testing the integrity of a seal of a plastic container according to the present invention, when a sealed plastic container 3 transported along a transportation conveyer 2 passes between a first sensing unit 5 and a second sensing unit 6, by arranging Sl between the first sensing unit 5 and the second sensing unit 6 smaller than a diameter dl of a body 3a of the plastic container 3, the body 3a of the plastic container 3 is compressed inwardly by the first sensing unit 5 and the second sensing unit 6, repulsive pressure P _a of the plastic container 3 is relatively applied to the first sensing unit 5 and the second sensing unit 6, the repulsive pressure P _a of the plastic container 3 is measured by the first sensing unit 5 and the second sensing unit 6, then, measurement values measured by the first sensing unit 5 and the second sensing unit 6 are provided to a control unit 7, and a seal condition (good or bad) of the plastic container 3 whether the measurement values are between the upper limit P _H and lower limit P _L of a set value is determined by the control unit 7.

[30] After the plastic container 3, such as a plastic milk bottle or the like which has been produced in the Republic of Korea, is filled with a liquid product, an opening 3b of the plastic container 3 is closed by a cap 4a and sealed by a sealing material 4b.

[31] The first sensing unit 5 and the second sensing unit 6 are load cells. Since the load cell has been well-known, no detailed description of the load cell will be presented.

[32] The control unit 7 converts output values of the first and second sensing units 5 and 6 into digital values to be received, reads an average value obtained by dividing a sum of the measurement value of the first sensing unit 5 and the measurement value of the second sensing unit 6 by two as an input value, and checks a transition of the input value (repulsive pressure) according to time, to determine the seal condition of the sealed plastic container as normal/good when a peak value P _MAX of the input value is between the upper limit P _H and lower limit P _L of the set value and to determine the seal condition of the sealed plastic container as abnormal/bad when the peak value P _MAX is over the upper limit P _H of the set value or under the lower limit P _L of the set value.

[33] For example, when the peak value is over the upper limit of the set value, since the liquid product contained in the plastic container 3 may be considered as being deteriorated irrespective of the seal condition of the plastic container 3, it is determined as bad. When the peak value is under the lower limit of the set value, the seal condition of the plastic container is determined as bad. Further, when the sealing material to seal the opening of the plastic container 3 fails to completely seal the plastic container 3, the body 3a of the plastic container 3 is pressurized so that even the slightly incomplete sealed part is broken, thereby preventing a defective product from being sold.

[34] The upper limit value and the lower limit value are different depending on the capacity of the plastic container 3 but the upper limit and lower limit of the set value of a relevant plastic container 3 may be predetermined through a test.

[35] Referring to FIGS. 3 through 5, in the apparatus for testing the integrity of a seal condition of a plastic container 3, the fist sensing unit 5 is mounted onto a pressurized bearing Bi _p secured to a first driving belt 10, among a number of bearings Bi po- sitioned inside the first driving belt 10, to measure the repulsive pressure P _a of the plastic container 3 applied to the pressurized bearing B _lp , and the second sensing unit 6 is mounted onto a pressurized bearing B _2p secured to a second driving belt 20, among a number of bearings B ₂ positioned inside the second driving belt 20, to measure the repulsive pressure P _a of the plastic container 3 applied to the pressurized bearing B _2p , wherein the pressurized bearing B _lp of the first driving belt 10 and the pressurized bearing B _2p of the second driving belt 20 are positioned to be opposite to each other at either side of the transportation conveyer 2, a first horizontal frame 11 onto which the first driving belt 10 is mounted and a second horizontal frame 21 onto which the second driving belt 20 is mounted are mounted onto a space control unit 30 to control the space between the first driving belt 10 and the second driving belt 20, and the space control unit 30 is connected to an up/down movable panel 41 of a height control unit 40 to control a height position of the up/down movable panel 41.

[36] The first driving belt 10 and the second driving belt 20 need to be rotated by their respective driving motors 12 and 22, and a rotation speed needs to be controlled so that the plastic container 3 transported by the transportation conveyer 2 can pass the pressurized bearings Bi _p and B _2p , without falling or being pushed backward.

[37] Again referring to FIGS. 3 and 4, in the space control unit 30, a first support member

31 is mounted onto the first horizontal frame 11, a second support member 32 is mounted onto the second horizontal frame 21, a left screw unit 33a of a screw shaft 33 is mounted onto a nut member 34 mounted onto the first support member 31, a right screw unit 33b of the screw shaft 33 is mounted onto a nut member 35 mounted onto the second support member 32, a handle 36 is mounted onto one end of the screw shaft 33, the first support member 31 and the second support member 32 are mounted onto two guide rods 37 and 38, movements of the first support member 31 and the second support member 32 are guided by the two guide rods 37 and 38, and each one end of the guide rods 37 and 38 is connected to the up/down movable panel 41.

[38] In the above-described constitution of the space control unit 30, when the handle 36 is turned in any one direction, the space between the first horizontal frame 11 and the second horizontal frame 21 becomes narrower by the screw shaft 33, and when the handle 36 is turned in the other direction, the space between the first horizontal frame 11 and the second horizontal frame 21 becomes broader by the screw shaft 33.

[39] Using the handle 36, the space of the first driving belt 10 and the second driving belt

20, that is, the space Sl between the first sensing unit 5 and the second sensing unit 6, is controlled according to the size of the plastic container 3, and furthermore, the pressure applied to the plastic container 3 and the repulsive pressure P _a of the plastic container 3 are controlled.

[40] Referring to FIG. 4, in the height control unit 40, a vertical screw shaft 42 is mounted onto a middle horizontal part Ia of a base frame 1 so as to be moved up/down by a handle 43, a top end of the vertical screw shaft 42 is mounted onto the up/down movable panel 41, the guide rod 44 is mounted onto the middle horizontal part Ia and a top horizontal part Ib of the base frame 1, and the up/down movable panel 41 is mounted onto the guide rod 44 so that, when turning the handle 43 in any one direction, the vertical screw shaft 42 moves up and the up/down movable panel 41 moves up along the guide rod 44 and when turning the handle 43 in the other direction, the vertical screw shaft 42 moves down and the up/down movable panel 41 moves down along the guide rod 44.

[41] Referring to FIG. 5, the apparatus for testing the integrity of a seal of a plastic container further comprises: photo sensors 50 and 51 onto which the first horizontal frame 11 and the second horizontal frame 21 are respectively mounted to sense the plastic container 3 pulled between the first driving belt 10 and the second driving belt 20; and a pushing unit 60 mounted onto exits of the first driving belt 10 and the second driving belt 20 to push out the plastic container 3 which seal condition is determined as bad by the control unit 7.

[42] As illustrated in FIG. 5, the apparatus for testing the integrity of a seal of a plastic container further comprises: a pair of feeder screw units 70 to control the space between the plastic containers 3 pulled into entrances of the first driving belt 10 and the second driving belt 20. When any plastic container 3 transported along the transportation conveyer 2 is pulled into the entrances of the feeder screws 70, the movement speed of the pulled plastic container 3 increases to broaden a space between the adjacent (subsequent) plastic containers 3 passing between the first driving belt 10 and the second driving belt 20, so that the first and second sensing units 5 and 6 have the measurement space.

[43] The apparatus for testing the integrity of a seal condition of a plastic container according to the present invention is capable of adjusting the positions of the first driving belt 10 and the second driving belt 20 depending on the size of the plastic container 3 by using the space control unit 30 and the height control unit 40. That is, the height control unit 40 is used to position the first driving belt 10 and the second driving belt 20 at the body 3a of the plastic container 3 transported along the transportation conveyer 2 and the space control unit 30 is used to adjust the space between the first driving belt 10 and the second driving belt 20, thereby controlling the pressure applied to the plastic container 3 and the repulsive pressure P _a of the plastic container 3. Further, the photo sensors 50 and 51 sense the plastic container 3 pulled between the first driving belt 10 and the second driving belt 20 so that, among the plastic containers 3 passing the first and second sensing units 5 and 6, the plastic container 3 determined as being bad by the control unit 7 is pushed from the transportation conveyer 2 by the pushing unit 60.