US3371781A - Apparatus for inspecting sealed containers - Google Patents

Description

Marlh 1968 ca. 0. ARMBRUSTER ET AL 3,371,781

APPARATUS FOR INSPECTING SEALED CONTAINERS Filed April 12, 1965 4 Sheets-Sheet 1 Inventors Geo/2&5 D. flknamyra Hausa J Ewe/5 5y March 1968 e. D. ARMBRUSTER ET AL 3,371,781

APPARATUS FOR INSPECTING SEALED CONTAINERS Filed April 12, 1965 v 4 Sheets-Sheet 2 m ML ER J. R/NGEL krrozmsys March 1968 G. n. ARMBRUSTER ETAL 3,371,781

APPARATUS FOR INSPEGTING SEALED CONTAINERS Filed April 12, 1965 4 Sheets-Shet a Inventors GEORGE aqzmszu rm /nLTE/z J. R/NGE L BY w ' HrTOeNEYS Match 5, 1968 G. D. ARMBRUSTER ET AL 3,371,781

APPARATUS FOR INSPECTING SEALED CONTAINERS Filed April 12, 1965 4 Sheets-Sheet 4 I22 I20 I Inventor: Gsozes OHRMBRUSTER ML ER JR/NGEL. BY (,I) fl- 210-4 Arr-MEX;

United States Patent ABSTRACT OF THE DISCLOSURE Apparatus for inspecting sealed containers at high production rates to determine whether or not an adequate vacuum exists within the container. A proximity sensor is mounted to be accurately positioned with respect to a flip panel in the container cap, regardless of variations in container height or cocking or tilting of the cap on the container.

The present invention has particular utility in inspecting baby food jars although it is obviously not limited to this particular field. Baby food containers conventionally take the form of a glass jar having a metal cap provided with a centrally located flip panel which assumes a con cave configuration when a s'uflicient vacuum exists within the jar and assumes a convex configuration in the absence of a sufficient vacuum. In the usual case, the food is placed in the jar and the head space in the jar is filled with steam before the cap is put on. As the jar contents cool, the steam condenses thereby forming a vacuum in the head space of the container if the container is properly sealed and the formation of this vacuum deflects the flip panel in the container cap to its concave position. The flip panel maintains this position as long as the vacuum exists within the jar, thus providing a continuous indication as to whether or not the jar is properly sealed. Sealing of the jar is of critical importance because an improper seal admits air into the jar, causing spoilage of the food.

While it is possible to visually inspect the sealed jars to determine whether or not the flip panel is in its vacuum indicating concave position, it is simply not economically practical to visually inspect these containers because of the tremendous volume of such containers which are marketed. Under normal conditions, to be economically practical the inspection system must be capable of inspecting the containers at rates in the order of 1000 containers per minute. Combined with the high production rate is the fact that packing techniques have reached a point where the number of improperly sealed containers is extremely small and may be, on the average, as low as one dud container out of 2500. Even with such a low rate of dud containers, where spoilage of baby food is concerned, it is obviously essential to accurately inspect each individual container.

A further problem arises in that the manufacturing tolerances of the glass jars employed as baby food containers are such that the permissible height variation is within a tolerance range of plus or minus of an inch. This gives a total possible height variation of A of an inch between jars of minimum and maximum height, a dimension which is of appreciable magnitude compared to the deflection range of the flip panel which is approximately .050 inch. Also, in some instances where screw 'caps are employed, the cap will not be properly threaded It is a primary object of the present invention to provide methods and apparatus for inspecting containers having flip panel tops which is operable and effective to detect and eject improperly sealed or dud containers from a packing line operated at a high rate of speed.

It is another object of the present invention to provide methods and apparatus for inspecting sealed containers having vacuum indicating flip panel tops which automatically compensate for varying container heights within a manufacturing tolerance, which variations may be of substantial magnitude as compared to the range of deflection of the flip panel.

It is another object of the invention to provide methods and apparatus for inspecting sealed containers having a vacuum indicating flip panel top which are adapted for use with proximity detecting sensor devices.

The foregoing, and other objects, features and advantages of the present invention will become apparent by reference to the following specification and to the drawings.

In the drawings:

FIGURE 1 is a side elevational view, with certain parts broken away or omitted, showing one form of apparatus embodying the invention;

FIGURE 2 is a detail top plan view of a portion of the apparatus of FIGURE 1 with certain parts broken away, omitted or shown in section;

FIGURE 3 is a detail cross sectional view taken on line 3-3 of FIGURE 2;

FIGURE 4 is a detail cross sectional view taken on line 4-4 of FIGURE 2;

FIGURE 5 is a detail cross sectional view taken on line 5-5 of FIGURE 2;

FIGURE 6 is a detail cross sectional view of a typical container top or cap which the apparatus of FIGURE 1 is operable to inspect;

FIGURE 7 is a partial side elevational view of a baby food jar or the like with the jar finish and cap shown in section;

FIGURE 8 is an end elevational view, partially in section, showing a modification of the apparatus of FIG- URE 1;

FIGURE 8a is a detail cross sectional view of a container employing another form of cap;

FIGURE 9 is a cross sectional view taken on line 9-9 of FIGURE 8;

FIGURE 10 is a schematic diagram of the control circuit or the embodiment of FIGURE 1; and

FIGURE 11 is a schematic diagram of a portion of a control circuit employed in the embodiment of FIG- URES 8 and 9, the omitted portions of the FIGURE 11 circuit being identical to the corresponding portions of the circuit of FIGURE 10.

Referring particularly to FIGURES 1 through 5, one form of apparatus embodying the present invention includes an endless belt conveyor designated generally 20 which is operable to convey containers C to be inspected along its upper run 22 in a direction from right to left as viewed in FIGURE 1. Conveyor 20 is driven in continuous movement by a schematically illustrated drive motor 24 and sealed containers C are fed by suitable mechanism, not shown, onto the right hand end of upper rim 22 and are fed onto a suitable takeout, not shown, at the left hand end of upper run 22. Because of a required high capacity of these units, normally in the range of 1000 containers per minute, the containers passing along conveyor 20 are in an abutted single line.

An inspection station designated generally 26 is mounted in operative relationship to the upper run of conveyor 20 and includes a pair of side plates 28 and 30 (FIGURE 2) which form a part of or are fixedly mounted upon fixed elements of the frame of conveyor 20. A pair of opposed guide rails 32 and 34 are mounted upon side plates 28 and 30 respectively to guide containers C during their transit of inspection station 26 to positively locate the containers transversely of the conveyor. Guide rails 32 and 34 are mounted upon side plates 28 and 30 by angle brackets 33 fixedly secured as by bolts to the respective guide rails. Angle brackets 38 are slidably supported upon fixed brackets 42 fixedly secured to side plates 28 and 3t} and are clamped in adjusted position transversely of the conveyor by bolts 44 which pass through elongate slots and angle brackets 38 and are threaded into fixed brackets 42.

A rigid angle member 46 has a vertical arm 43 which is clamped into face-to-face engagement with side plate 28 by a pair of clamping screws 50 which pass through elongate slots 52 in arm 48 to accommodate vertical adjustment of member 46. A positioning screw 54 passes downwardly through a bore 56 in the horizontal arm 58 of member 46 and is threaded through a fixed nut 6t? Welded to arm 48. The lower end 62 of screw 54 bears against the upper surface of plate 23 so that turning of screw 54 can vertically shift angle member 4-6 relative to the fixed member 28 when screws 59 are loosened.

A support plate 64 is supported upon the horizontal upper arm 53 of angle member 46 and is clamped to arm 58 in selected adjusted positions transversely of con veyor 20 by clamping screws 66 which pass through elongate slot 68 in plate 64 and are threaded into arm 53.

At the free end of support plate 64, a floating head assembly designated generally 70 is suspended at the underside of plate 64. Head assembly 70 includes a dish shaped support head 72 having an upwardly projecting central boss 72 which projects upwardly through a bore 76 through plate 64. Head 72 is suspended from plate 64 by four symmetrically located headed support pins 78. The shanks of pins 78 are slidably received within bores 80 which extend through plate 64 and the lower ends of pins 78 are fixedly secured, as by threaded engagement, into head 72. A compression spring 82 surrounds each pin 78 and bears between the lower surface of support plate 64 and the upper surface of head 72.

Bores 76 and 80 provide sufficient radial clearance between boss 74 and pins 80 so that head 72 can move upwardly freely from its lowermost position as determined by the engagement of the heads of pins 78 with the top of support plates 70, and this clearance also permits a limited tilting movement of head 72 which may be required by conditions to be described below.

In the particular example disclosed in the drawings, the apparatus is employed to determine whether or not a sealed container, such as a baby food jar, has a suflicient vacuum in the container. Referring to FIGURES 6 and 7, there is disclosed a closure cap frequently used for baby food jars. The particular cap disclosed is described in detail in US. Patent No. 3,152,711 and hence only those features of the cap germane to the present invention will be described in detail. Briefly, the cap, as shown in FIG- URE 6, includes a top panel which is formed with an upwardly projecting annular peripheral rim portion 84 and a centrally located flip panel 86 which normally assumes the convex configuration shown in full line in the cross sectional view of FIGURE 6. When the cap is in its sealed position upon a jar, FIGURE 7, and a satisfactory Vacuum exists within the jar, the vacuum within the jar causes flip panel 86 to deflect into the concave position shown in full line in FIGURE 7. In the event the cap is not adequately sealed to the jar, the vacuum is dissipated and upon the loss of vacuum within the jar, flip panel 86 will spring back upwardly into its original convex position illustrated in broken line in FIGURE 7.

The present invention is especially concerned with inspecting jars employing closures of this type to determine Whether or not an adequate vacuum exists within the container, the presence of the vacuum in turn indicating a satisfactory seal. Presence of an adequate vacuum is exhibited by a flip panel 86 in its concave position, while absence of a satisfactory vacuum is exhibited by the convex position of flip panel 86.

To sense the position of flip panel 86, a proximity sensor 88 is fixedly mounted within the boss of head 72. The particular proximity sensor employed takes the form of a commercially available proximity switch manufactured by the Micro Switch Division of Honeywell, Freeport, 111., and is described in detail in data sheet 213A supplement to Honeywell catalog 85. In brief, the sensor is connected to an oscillator which in turn is connected through an amplifier to a monostable flip flop which in turn controls a relay. The sensor is an integral part of the oscillator stage and when an electrically conductive object is located within the detection field of the sensor, the object absorbs oscillator energy which results in an amplitude change. This change controls the state of the monostable flip flop which in turn controls a relay. Basically, the sensor generates a signal to act as a switch when a metal object is moved into the field of the sensor.

Such devices can be adjusted to an extreme degree of sensitivity. With the particular cap disclosed, the total range of deflection of the cap between the convex and concave position is approximately .050 inch and commercially available sensors can be adjusted to detect the existence of the concave or convex position of the flip panel of the cap.

However, with the particular baby-food type jar shown in the drawings, a problem is presented in that the ordinary manufacturing tolerances of such jars permit a height variation in the completed jar of plus or minus of an inch or a total height variation of A of an inch which is of appreciable magnitude as compared to the total range of deflection of the flip panel of the cap.

In order to compensate for this height variation while at the same time accurately locating sensor 88 at a predetermined elevation relative to the top panel of the cap, the underside of head 72 is formed with a downwardly projecting annular ri-m 90 which is adapted to rest upon the peripheral rim portion 84 of the container cap as the container is brought into registry beneath the head. Springs 82 and the floating mounting of head 72 upon support plate 64 permit the head to elevate and depress to compensate for containers of varying heights. The normal rest position of head 72, determined by adjustment of pins 78 and the height adjustment of angle mernber 46 is selected to be such that the lower surface of head 72 is spaced above conveyor 20 by a distance less than the minimum container height.

In order to accurately inspect 'all containers, it is necessary that head 72 further be capable of tilting movement out of a horizontal plane to accurately sense the presence or absence of a satisfactory vacuum in a container in those cases where the container cap may be cocked, as by an improper engagement of the cap with the screw thread on the container finish. Where the cap is not properly threaded onto the container, it is almost inevitable that the vacuum within the container has been lost, and unless the head can tilt, the head is elevated to the highest point of the tilted jar rim, thus spacing the sensor 88 farther from the center of the cap than normal. This leads to the possibility of failing to detect an improperly sealed container. The clearances provided by bores 76 and permit the head to tilt so that full contact through 360 is achieved between rim and head 72 and the peripheral rim portion 84 of the cap even though the cap or container may be tilted during its pass-age beneath the inspection head.

To eject those containers having an unsatisfactory vacuum, a pneumatic differential motor 92 is mounted upon a plate 94 which, as best seen in FIGURES 2 and 5, is mounted for adjustment longitudinally of conveyor 20 by clamping bolts 96 which pass through elongate slots 98 in plate 94 and are threaded into a second plate 100.

Plate 100 in turn is mounted for adjustment transversely of conveyor 20 by a dovetail groove 102 engagement with a third plate 104. Plate 104 is an angle member whose horizontal arm is slidably engaged with plate 100 and whose vertical arm is 'adjustably clamped for vertical adjustment of the entire assembly upon plate 28 by clamping screws 106 which pass through an elongate slot 108 in the vertical arm of member 104. A clamping screw 110 passes upwardly through an elongate slot 112 (FIGURE 5) and is threaded into plate 100.

From the foregoing, it is believed apparent that motor 92 can be adjustably positioned vertically, transversely, and longitudinally relative to conveyor 20. The purpose of the universal positioning of motor 92 is to enable a precise and accurate location at which the piston rod 114 of motor 92 strikes the container. Piston rod 114 is normally located in a retracted position clear of the path of containers upon conveyor 20. Upon the detection of a container with an unsatisfactory vacuum by sensor 88, motor 92 is actuated to extend its piston rod, the piston rod tip 116 striking the detected container to eject the container from the conveyor onto a table, not shown, located on the opposite side of the conveyor from motor 92. Vertical adjustment of motor 92 is essential so that tip 116 of piston rod 114 will strike the container in a horizontal plane containing the center of gravity of the container.

Adjustment of motor 92 longitudinally of the conveyor is essential in order that the tip 116 will strike the container in line with the vertical center line of the cylindrical container. Because of the inherent delay between the triggering of the sensor and the stroking of piston rod 114, it is'necessary that the longitudinal axis of piston rod 114 be located slightly downstream of the conveyor from the center line of sensor 88. This distance must, of course, be calibrated both in terms of the reaction time delay between the triggering of the sensor and the stroking of the piston rod 114 and the speed of travel of the containers along conveyor 20.

Adjustment of motor 92 transversely of the conveyor is likewise related to the speed of travel of the containers along the conveyor. In the usual case, the conveyor speed is such that containers areconveyed past the inspecting head at rates in the order of 1000 containers a minute. The containers are fed along the conveyor in single line in contact witheach other and thus, when a container is to be ejected, it is necessary that the piston rod perform its function of ejecting the dud container and retracting before the next successive container reaches the piston rod. In order to accomplish this, motor 92 is a relatively small pneumatic motor, a motor with a inch bore and a /2 inch stroke having been effectively employed. To simplify the motor actuation, a full stroke of the motor is employed, and by adjusting the position of motor 92 transversely of the conveyor the piston rod projects into the path of travel of the containers only by a selected distance determined by adjusting the position of the cylinder of motor 92 toward or away from the path of travel of the conveyor. To further minimize possible interference, tip 116 is constructed in a conical shape and to cushion the striking of the tip against the container, tip 116 is made of rubber or other suitable resilient material. The ejecting of the container is accomplished by striking and knocking the container out of line rather than merely pushing the container to one side.

The cont-r01 circuit is schematically shown in FIGURE 9. Sensor 88 is connected by its output lead 120 to an amplifier 122. Amplifier unit 122 is commercially available from the manufacturer of sensor 88 and suitable units are described in the micro switch data sheet 213A referred to above. In wsence, sensor 88 and amplifier unit 122 act at a switch to electrically connect a solenoid 124 to electric power supply line L1 and L2 when the sensor detects a dud container. Solenoid 124 forms a part of a solenoid actuated 3-way valve designed generally 126 which is of a commercially available construction. The specific valve disclosed is manufactured and sold by Ross Operating Valve Company of Detroit, Mich., under catalog No. 1613A2001 and is in essence a normally closed 3-Way valve which alternatively connect. a head end conduit 128 to an atmospheric vent 130 or to a high pressure supply conduit 132 which is connected to a pressure source 134 through a pressure regulator 136. The normal connection of valve 126 is to connect head end conduit 128 to vent 130 as shown in FIGURE 10, when the solenoid is de-energized. Upon energization of solenoid 124, the connections of valve 126 are switched to connect high pressure conduit 132 to head end conduit 128.

The rod end of the cylinder of motor 92 is connected by a rod end conduit 138 to a pressure accumulator 140 which in turn is connected to pressure source 134 via a conduit 142 having a second pressure regulator 144 connected in the conduit. Accumulator 140 (see FIGURE 1) is a simple air chamber whose volume may be adjusted as by an adjusting screw 146. Pressure regulators 136 and 144 are set so that a relatively high pressure, such as 60 p.s.i., exists in conduit 132 while a relatively low pressure of approximately 5 p.s.i., for example, is normally maintained in accumulator 140 and rod end conduit 138.

Referring to FIGURE 10, with the control circuit in its normal condition a pressure of 5 p.s.i. is applied to the rod end of the cylinder of motor 92, thereby urging piston rod 114 to its retracted position, the head end of motor 92 being connected to vent. Upon the sensing of a dud container by sensor 88, solenoid 124 of valve 126 is energized and the valve connections are shifted to connect head end conduit 128 to high pressure conduit 132, thereby applying 60 p.s.i. to the head end of the cylinder of motor 92. Because of the small internal dimensions of motor 92, the 55 p.s.i. differential pressure applied to the head end of the motor drives piston rod 114 to its fully extended position almost immediately. In so doing, air ahead of the piston is forced from the cylinder through rod end conduit 138 into the chamber of accumulator 140. By adjusting the volume of the chamber of accumulator 140, the pressure in chamber 140 can be built up above its normal 5 p.s.i. pressure to some value well below 60 p.s.i., as for example 20 p.s.i.

From the foregoing, it is seen that the ejecting stroke of piston rod 114 is extremely rapid and the high speed movement of the piston rod in its outward stroke almost instantaneously knocks the dud container out of the line of containers and oif the opposite side of the conveyor. 1

The time period of energization of solenoid 124 is determined by operating characteristics of sensor 88 and amplifier unit 122. The time delay between actuation of sensor 88 and energization of solenoid 124 is dependent upon the particular sensor-amplifier unit combination chosen, operating response times of commercially available equipment varying between 5 and 40 milliseconds. The release response time or time period between energization and de-energization of solenoid 124 is dependent both on the characteristics of the system and the sensing distance and can be varied between 8 and 120 milliseconds. A further release response delay is encountered in the time required to physically shift valve 126 from its actuated position to its vent position. Shifting movement of the valve from its normal vent position to actuated position, as well as the operating response time of the sensor system, is compensated for by the positioning adjustment of motor 92 longitudinally of the conveyor.

Because of the small chamber dimensions of the cylinder of motor 92, valve 126 need be connected to supply pressure to the head end of motor 92 for only an extremely short period of time because the motor strokes to its fully extended position almost instantaneously. The release response time is thus chosen to be as short as possible consistent With a full stroke of piston rod 114. Thus, after actuation solenoid 124 is de-energized almost immediately and the valve returns to the normal position as 7 shown in FIGURE in which the head end of motor 92 is vented. The pressure accumulated in accumulator 140 acts immediately to drive the piston in its return stroke.

A modification of the invention is disclosed in FIG- URES 8, 8a, 9 and 11. In some instances, the configuration of the top surface of the cap is such that the sensitivity of the sensor can not be adjusted to distinguish between the mass of metal at the cap rim and the flip panel at the center. Thus, with the single sensor employed in the embodiment described above, the configuration of the cap is such that the sensor is actuated both when the leading and trailing edge of the cap pass beneath the sensor. Such a cap is shown in FIGURE 8a having a top panel 200 which in general is perfectly flat except for the depressed flip panel 202 in the center section.

When a cap of this type is employed upon the containers, a second sensor 204 is added to the previously described embodiment and is mounted upon a bracket 206 attached to support plate 64. Sensor 204 is located with its longitudinal center line in the same vertical plane as sensor 88 and is located to be actuated by the metal of the cap rim when the cap is accurately centered under sensor 88. The two sensors are connected in series so that amplifier unit 122 is triggered only when both sensors 88 and 204 are simultaneously actuated. Sensor 204 will be actuated every time a container cap is centered beneath sensor 88, however at this time sensor 88 will not actuate unless the cap indicates an insufficient vacuum in the container. Sensor 88 will be actuated twice during the passage of each container, once as the leading portion of the cap passes beneath it and once as the trailing portion of the cap passes beneath it. However, at both these times, the spacing between sensor 204 and the cap is such that sensor 204 will not be actuated.

FIGURE 11 indicates schematically the electrical connections of the embodiment of FIGURES 8 and 9, the remaining portion of the pneumatic circuit having been omitted from FIGURE 11 since it is identical with the pneumatic circuit of FIGURE 10.

While two embodiments of the invention have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting, and the true scope of the invention is that defined in the following claims.

We claim:

1. In an apparatus for determining whether the vacuum in a sealed container is satisfactory where the container top has a centrally located flip panel which assumes a generally concave configuration when the vacuum in the container is satisfactory and a convex configuration when the vacuum in the container is unsatisfactory; the combination comprising conveyor means for moving containers in succession past an inspection station, a floating head element at said inspection station mounted for vertical movement and for tilting movement, a flat support surface on said head element adapted to be supported by the peripheral rim portion of a container top when the container is at said inspection station, sensor means mounted in said head element to be supported at a predetermined level relative to the rim portion of the container top in vertical registry with the flip panel therein when said support surface of said head element is supported by the rim portion of the container top, said sensor means being responsive to the proximity of the flip panel when in vertical registry therewith to generate a signal only when said flip panel is convex to a degree indicating an unsatisfactory vacuum in the container, and means responsive to the generation of a signal by said sensor means for ejecting the container from said conveyor means.

2. The combination of claim 1 wherein means for ejecting comprises a differential motor having a cylinder and a piston rod moveable transversely of said conveyor means between a normal retracted position clear of the path of containers along said conveying means and an extended position wherein said rod projects into the path of containers on said conveyor means, means for adjustably positioning the motor transversely of said conveyor to regulate the portion of the stroke of said rod into the path of containers, and means for adjustably positioning said motor longitudinally of said conveyor means to accommodate for movement of a container to be ejected along said conveyor means in the time interval between the generation of said signal and the stroking of said piston rod from said normal retracted position.

3. The combination of claim 1 wherein said means for ejecting further comprises a pressure source, and a differential motor having a cylinder and a piston rod, valve means normally connecting the head end of said motor cylinder to vent and operable in response to the generation of a signal by said sensor means to connect said head end to said source, and a pressurized accumulator chamber connected to the rod end of said cylinder, the pressure in said chamber when said piston rod is in its retracted position being substantially less than the pressure applied to said head end when connected to said source.

4. In an apparatus for determining whether the vacuum in a sealed container is satisfactory where the container top has a centrally located flip panel which assumes a generally concave configuration when the vacuum in the container is satisfactory and a convex configuration when the vacuum in the container is unsatisfactory; the combination comprising conveyor means for moving containers in succession past an inspection station, a support plate mounted in overlying relationship to said conveying means at said inspection station, a head element having a flat annular bottom surface suspended from said support plate for vertical movement relative thereto to and from a normal rest position at which the bottom surface of said head element is located in a horizontal plane below the minimum height of a container top above said conveying means and for tilting movement in which said bottom surface is inclined from said horizontal plane, said bottom surface being adapted to be supported by the peripheral rim portion of a container top when the container is at said inspection station, sensor means mounted in said head element to be supported at a predetermined level relative to the rim portion of the container top in vertical registry with the flip panel therein when the bottom surface of said head element is supported by the container top, said sensor means being responsive to the proximity of said flip panel to generate a signal only when said flip panel is convex to a degree indicating an unsatisfactory vacuum in the container, and means responsive to the generation of a signal by said sensor means for ejecting the container from said conveyor means.

References Cited UNITED STATES FATENTS 2,836,296 5/1958 Lewis 20988 3,206,025 9/1965 Ochs 209--88 3,206,027 9/1965 Bailey 209ll1.8

M. HENSON WOOD, 111., Primary Examiner.

R. A. SCHACHER, Assistant Examiner.

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