Culling method for blister-pack production line

Abstract

A continuous and elongated blister-pack strip having transverse rows of blisters of which some are empty and most are full is transported through a stamping station. Upstream of the stamping station whether any blisters entering the stamping station are full or empty is sensed. In the stamping station only sections all of whose blisters are full are stamped out of the strip from between the edges thereof while leaving the edges flanking the stamped-out section intact so that sections of the strip having at least one empty blister leave the stamping station attached to the strip edges. The stamped-out sections are transported away from the path at the stamping station. Spaces in the strip between blisters still attached to the strip edges are then detected and the entire strip is transversely cut only between the respective blisters into pieces each including at least one row of intact blisters.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of copending application Ser. No. 10/975,924 filed 28 Oct. 2004.

FIELD OF THE INVENTION

The present invention relates to a blister-pack production line. More particularly this invention concerns a method of culling out defective packages from such a line.

BACKGROUND OF THE INVENTION

It is standard to package small items, e.g. pills, in blister packs so that the contents of each blister are visible but hermetically sealed and well protected. Thus a standard blister-pack production line horizontally advances a lower foil formed with upwardly open pockets or blisters arrayed in transversely extending rows separated by transversely extending spaces. Each blister is loaded with one or a predetermined number of the objects being packed, then another foil is applied to the top face of the lower foil and the two foils are bonded together all around the blisters. Subsequently the two bonded foils, which normally move either continuously or in steps, pass through a stamping station where sections normally including a predetermined number of the blisters are punched out and passed on for further packaging.

Typically one or both of the foils is transparent and means such as described in German 42 43 206 of J. Oehlmann or 195 05 256 of U. Zietmann is used to verify that each blister is properly filled. It is extremely important that packages not be sent out with overloaded, underloaded, or empty blisters, especially as these blister packs are often used to ensure regular consumption of critical medications.

German 199 17 436 of A. Weinert et al describes such an arrangement in which immediately upstream of the stamping station where the continuous strip is subdivided into sections there is a monitoring station that scans the passing filled and bonded strip and that can distinguish between properly filled blisters and improperly filled ones. When a section is detected that is only partially filled, it is stamped out of the strip like the good sections but is subsequently routed off. When a section is detected that is completely empty, it is not stamped out but is left hanging on the strip for later chopping and use as regrind.

These systems are all fairly complex. They do not adequately segregate the unusable partially filled or empty sections from the good sections and from each other. Thus the culls can get back into the production line. Furthermore the culls themselves require considerable attention so that, for instance, valuable or dangerous medicaments are not chopped up.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide an improved culling method for a blister-pack production line.

Another object is the provision of such an improved culling method for a blister-pack production line that overcomes the above-given disadvantages, in particular that is simple, and that accurately separates filled usable strip sections, partially filled sections, and empty sections from one another.

SUMMARY OF THE INVENTION

A continuous and elongated blister-pack strip having transverse rows of blisters of which some are empty and most are full is transported through a stamping station. An upstream sensor along the path upstream of the station determines whether the blisters entering the station are full. A device in the station stamps out of the strip sections each including a plurality of blisters. A controller connected between the upstream sensor and the stamper for inhibits action of the stamper and thereby leaves unfilled blisters on the strip when any blisters in the station are not full. A conveyor transports the stamped-out sections away from the path at the station. A downstream sensor along the path downstream of the station detects spaces in the strip between any blisters left on the strip, and a cutter along the path downstream of and connected to the downstream sensor severs the strip between the rows of blisters into pieces each including at least one row of intact blisters.

Thus with this system the stamper only separates out perfect sections of the strip, that is sections all of whose blisters have the desired number of objects. If one blister is empty or overfilled, or even if it is improperly glued or has some other defect, the respective section is left on the strip. Then according to the invention the strip is cut into pieces between the rows of blisters so that the contents of any full blisters are not damaged. Since the strip remains continuous, with at worst holes where good sections have been punched out, it is extremely easy to handle.

According to the invention the downstream sensor also detects whether the blisters passing it are full or empty. The system further has according to the invention a deflector downstream of the cutter for separating the pieces all of whose blisters are empty from the pieces some of whose blisters are filled. The cut-off pieces that are completely empty can be chopped up and reused, for example, as regrind, or discarded. The more difficult to dispose of pieces holding product can be handled differently, for example the contents can be recovered or they can be treated as dangerous waste.

The cutter according to the invention includes a fixed blade to one side of the path and a rotating blade to an opposite side of the path. The rotating blade turns about an axis transverse to a direction of movement of the strip along the path. Its rotation is synchronized with the advance of the strip, something that is fairly easy as the strip is left continuous and quite easy to handle.

The upstream sensor in accordance with the invention includes a camera. The downstream sensor is normally a more simple light curtain that can also be set up to detect, when the foils making up the strip are transparent, whether any blisters of a given row are full.

The conveyor includes a suction lifter for picking the stamped-out sections out of the stamping station and a conveyor belt adapted to receive the stamped-out sections from the suction lifter and transport them from the station. Another sensor can be juxtaposed with the conveyor belt for detecting the stamped-out sections thereon.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIGS. 1 and 2 are partly schematic side views illustrating the system of this invention;

FIG. 3 is a perspective view of the system; and

FIG. 4 is a perspective view illustrating the package strip.

SPECIFIC DESCRIPTION

As seen in the drawing a strip 4 is moved in a transport direction D along a path through a stamping station 1 and comprises a lower foil formed with blisters 8 most of which are filled and an upper foil bonded over the lower foil. The blisters 8 are arrayed in six-abreast rows extending perpendicular to the direction D with gaps between adjacent rows where there is nothing but the thickness of the two foils forming the strip 4.

The stamping station 1 is provided with a device 5 that is capable of cutting from between the edges of the strip 4 a section 2 (see FIG. 4) here shown to have four rows of blisters 8, for a total of 24 blisters 8. A suction-type gripper 9 can pick up the stamped out sections 2 and deliver them to a conveyor belt 6 that carries them off, with the sections 2 hanging from the lower reach of this conveyor 6, for example held thereon by vacuum or an unillustrated pair of lower belts, past a sensor station 10 that verifies the passage of the sections 2.

A camera-type sensor 7 upstream of the stamping station 1 is connected to a controller 17 that only operates the device 5 when all of the blisters 8 in the section 2 to be stamped out are properly filled, that is each blister 8 has the desired number—normally one—of objects. Thus according to the invention if a section 3 (FIG. 4) has one or more empty blisters 8, it is not stamped out of the strip 4, but instead is left on it, and in fact the strip 4 is left as two continuous edge bands where the sections 2 have been punched out, so that it remains extremely easy to handle and guide.

Downstream of the station 1 the strip 4 passes between a pair of belts 18 that feed it past a light-curtain sensor 15 formed as a simple photocell and lamp directed transversely across the path of the strip 4 and serving to distinguish between regions of the strip 4 with blisters 8 and those without. This sensor 15 is connected via the controller 17 with a cutter 12 comprised of a stationary blade 14 and a rotary blade 13. The blade 13 is spun by a motor 19 operated by the controller 17 so as to cut the strip 4 between rows of blisters 8. Thus the cutter 12 will not indiscriminately chop up the strip with its full and empty blisters 8, but will chop it into transverse strips each holding one or more rows blisters 8. Never will a blister 8 be cut.

In fact the sensor 15 is also capable of determining whether any of the blisters 8 in a given row or in a passing cull section 3 is full and a deflector 16 downstream of the cutter 12 is operated by the controller 17 to deflect the chopped-off rows of blisters 8 from the strip 4 into either a passage 20 for completely empty blisters, or a passage 21 for rows having at least one full blister. The completely empty blisters can be simply chopped up and recycled as regrind. The partially full blisters can be emptied of their contents and then comminuted, or otherwise handled.

Claims

1. A method of making blister-pack packages, the method comprising the steps of:

displacing along a longitudinal path through an upstream detecting station, a stamping station downstream of the upstream station, and a downstream detecting station downstream of the stamping station a continuous longitudinally elongated blister-pack strip having transverse rows of blisters of which some are empty and most are full, the rows of blisters being flanked by longitudinal edges of the strip;

sensing at the upstream detecting station whether any blisters entering the stamping station are full or empty;

in the stamping station stamping out of the strip from between the edges thereof only sections all of whose blisters are full while leaving the edges flanking the stamped-out section intact so that sections of the strip having at least one empty blister leave the stamping station attached to the strip edges;

transporting the stamped-out sections away from the path at the stamping station; and

detecting in the downstream detecting station spaces in the strip between blisters still attached to the strip edges and there transversely cutting the entire strip only between the respective blisters into pieces each including at least one row of intact blisters.

2. The packaging method defined in claim 1 wherein the stamped-out sections are transported away from the path at the stamping station by means of a suction lifter that picks the stamped-out sections up out of the stamping station.

3. The packaging method defined in claim 1, further comprising the step of

at a second detecting station downstream of the first downstream detecting station detecting station detecting whether the blisters passing are full or empty; and there

separating any pieces all of whose blisters are empty from the pieces some of whose blisters are filled.

4. The packaging method defined in claim 3, further comprising the step of

transporting the separated pieces away from the path.

5. The packaging method defined in claim 1 wherein pieces are transported away by a conveyor belt

6. The packaging method defined in claim 5, further comprising the step of

continuously operating the conveyor belt and

detecting the stamped-out sections thereon.

7. The packaging method defined in claim 1 wherein the pieces each include only one row of blisters.