INTRODUCTION

The present invention relates generally to cuvettes for use in the chemical analysis of fluid samples in an automated instrument and, more particularly to flexible cuvette belts consisting of a plurality of integrally interconnected cuvettes which are designed to be transported through such an instrument, and the manufacture of such belts.

BACKGROUND OF THE INVENTION

A variety of automated or semi-automated chemical analyzers are known which utilize cuvettes for the chemical testing of samples placed therein. Generally, a predetermined amount of liquid sample, such as a biological fluid, is placed in the cuvette

which is then transported through the instrument. As the cuvette is being transported, the instrument dispenses a quantity of reagent into the-sa ple and monitors the resulting chemical reaction. Such monitoring is generally accomplished through use of an optical means which views the fluid sample through optically transparent portions of the cuvette.

In order to simplify the loading of the cuvettes into the instrument and facilitate their handling by the instrument once so loaded, proposals have been made to provide the cuvettes in the form of a continuous integral strip. The individual cuvettes of the strip are designed to be relatively rigid, but the strip itself is provided with sufficient flexibility to ease its transport through the instrument. Furthermore, by making the cuvettes in a continuous strip form, they can be manufactured relatively inexpensively from suitable plastic material, thereby permitting their disposal after use. This is an important feature since it avoids the requirement of washing the cuvettes after use and avoids any possibility of cross-contamination of fluid samples whichcould cause erroneous test results. A proposed

cuvette system designed to meet these requirements is disclosed in US Patent No. 4,263,256.

In commonly owned co-pending US Patent Application ,Serial No. 284,842, filed July 20, 1981 and entitled "Cuvette System For Automated Chemical Analyzer", the disclosure of which is hereby incorporated by reference in its entirety herein, there is described a cuvette belt which comprises a matching pair of elongated, formed plastic strips which are joined together along corresponding faces thereof to form an integral belt. • A series of regularly spaced chamber halves are formed transversely in each of the corresponding strip faces which define open-topped cuvette receptacles when the belt halves are joined. As described, the cuvette belt is made by forming strip plastic material with a series of regularly spaced transverse ( laterally extending) formed pockets so as to define to integral side-by-side belt halves. The formed strip is then divided longitudinally to separate the belt halves and the belt halves brought into register and joined together to form a completed cuvette belt.

The present invention is concerned with

i proved methods and apparatus for manufacturing integral cuvette belts of the kind described above.

5 SUMMARY QF THE INVENTION

One aspect of the invention is concerned with an improved manufacturing process which allows two cuvette belts to be manufactured simultaneously.

10 According to this aspect of the invention two strips of plastic material are advanced in turn to a series of processing stations including a forming station or a formed strip supply station, a sealing station and a slitting station arranged in that order.

15 In one embodiment, at the forming station each strip of plastic material is formed with a series of regularly spaced transverse elongated pockets so as to define two integral side-by-side mirror image cuvette belt halves. The two formed strips are then

20. advanced to the sealing station at which they are brought into register and joined together to form a composite strip defining two integral side-by-side mirror image cuvette belts. From here the composite

strip passes to the slitting station where it is divided longitudinally to separate the cuvette belts.

In one embodiment of such belt making apparatus, the two plastic strips are formed in separate forming presses arranged one above the other.

For best results it has been found that the pockets should be pressed upwardly out of the strip material. Accordingly the presses are preferably identical, which has the advantage of a common design and parts, in which case the two strips face the same way when they leave their respective presses. In order to orient them correctly for joining together, the lower formed strip is twisted through 180° before it meets the upper strip. The other aspect of this invention is concerned with the manner of advancing the strip material through the process stations which permits the most effective operation of each process station to be achieved in a continuous in-line arrangement. According to this aspect of the invention, plastic strip material is advanced in turn to a series of processing stations including a forming station or, alternatively, a formed strip supply station, a

slitting station and a sealing station and is indexed stepwise through one or more of the stations while being advanced in continuous motion through the remaining station or stations. Such a system is applicable to both of the belt making process described above, i.e. where a single strip is formed to define two integral belt halves, slit down the middle to separate the halves which are then joined together to form one cuvette belt, or where two strips are formed in the same way, brought together to form a composite strip defining two integral cuvet e belts and then the composite strip slit down the middle to separate the cuvette belt. In a further variation, two strips could be formed as described above to define two integral belt halves, each strip slit down the middle to separate the belt halves and then- the separated belt halves joined together to form two cuvette belts simultaneously.

In one such embodiment, the or each strip is advanced through the forming and sealing stations in indexing steps and through the slitting station in continuous motions. This arrangement enables the most effective operation at each station. Thus batch mode

operation is most effective for sealing the strips while continuous operation of the slitter is most effective for separating the strips.

While the or each complete, separate cuvette belt produced may be advanced direct to a spooling station where it is wound on a storage spool, preferably the belt or belts are advanced through at least one inspection station and a station for removing defective cuvettes. Advantageously the belt(s) may be advanced stepwise through the inspection station and in continuous motion through the removal station. In one embodiment, the or each belt may be advanced through a visual inspection station, the indexing of the belt in this station being under operator or manual control.

DESCRIPTION OF TIE DRAWINGS

Other features and advantages of the invention will become apparent from the following description taken in conjunction with accompanying drawings wherein:

Figure 1 is an end view of a strip of

laminated plastic material suitable for use as stock material in the manufacture of cuvettes in accordance with the present invention.

Figure 2 is a top plan view of the strip material shown in Figure 1 after pockets and indexing perforations have been formed therein according to the process of this invention to define two integral mirror imaged cuvette belt halves.

Figure 3 is an end view of the formed strip shown in Figure 2,

Figure 4 is a side view showing two formed strips of Figure 2 joined together to form a composite strip defining two integral mirror image cuvette belts.

Figure 5 is an end view of the composite strip show in Figure 4,

Figure 6 is a side view of a cuvette belt after separation of the composite strip.

Figure 7 is an end view of the cuvette shown in Figure 6, Figure 8 is a perspective view of a portion of the cuvette belt shown in Figure 6,

Figure 9 is a partial sectional top view through the cuvette belt shown in Figure 8,

Figure 10 is a schematic side elevation of one embodiment of cuvette belt manufacturing apparatus according to the present invention, and

Figure 11 is a schematic top plan view of the apparatus of Figure 10.

DESCRIPTION p_F THE PREFERRED EMBODIMENTS

Referring to the accompanying drawings.

Figures 1-9 illustrate one embodiment of the general process of manufacture of cuvette belts, in accordance with this invention and a cuvette belt produced by the process while Figures 10 and 11 illustrate a cuvette manufacturing apparatus according to the invention for manufacturing cuvette belts in which the belts are formed by advancing webs of plastic material through a series of in-line processing stations. It is to be understood, however, that other embodiments of the invention are possible such as replacing the forming station with a formed plastic strip supply station. In this case, the forming station, per se, may be separated from the remainder of the process stations.

Referring to Figures 10 and 11, there is shown one embodiment of apparatus according to the invention for making cuvette belts from strip plastic material which is advanced in turn to an in-line series of processing stations to produce the completed belts.

The apparatus illustrated simultaneously forms two cuvette belts lO ^' from two strips of plastic material 20a, 20b ( one of which is shown in Figure 1 ).

Each strip 20 is formed at a forming station 102 with regularly spaced, transverse pockets so as to define two integral, side-by-side mirror image belt halves (Figures 2 and 3). The two formed strips are then brought into face-to-face register and joined together at a sealing station 104 to form two integral, side-by- side mirror image cuvettes (Figures 4 and 5). The joined strips are thereafter slit longitudinally along their center lines at a slitting station 106 to produce two identical cuvette belts 22a, 22b in a single operation (one of which is shown in Figures 6 and 7).

The cuvette belts 22 are formed from elongated strips of plastic material which are suitably obtained by sheet stock material into strips. ' These

strips 20 should be of sufficient length to provide completed cuvette belts of the desired length and in particular of sufficient length to permit the continuous operation of an automated clinical analyzer in which they are to be used. For example, the desired length of a cuvette belt for use in a Paramax Analytical System as manufactured by American Hospital Supply Corporation is 2000 cuvettes long.

An important feature of a cuvette belt for use in such an analyzer is that the individual cuvettes have closely controlled dimensional accuracy and provide a precisely def ined ^' optical path through the cuvette. It has been found that copolyester or vinyl plastic strip stock in thickness of 0.005 to 0.010 inch provides satisfactory results when formed according to the present invention.

A suitable example of such material is KODAR brand Thermoplastic Polyester Resin manufactured by Eastman Chemical Co. In order to facilitate the fabrication and assembly of the cuvette belt, the strip stock is preferably a laminate, having a layer ^" of easily sealable and biologically inert material such as SURLYN brand Ionomer Resin Material manufactured by

E.I. duPont de Nemours & Co., Inc. Figure 1 shows a suitable laminated strip 20 formed of a KODAR layer 41 and a SURLYN layer 42 laminated together. —

In the manufacture of cuvette belt 22 using the apparatus and process of the present invention, two strips 20 of stock plastic material as shown in Figure 1 are identically formed with a series of regularly spaced formed transverse shallow pockets as shown in Figures 2 and 3. Each formed strip defines two integral side-by-side mirror belt halves 26, 27. The pockets are formed as narrow, shallow indentations having a generally rectangular shape utilizing cold forming techniques to avoid any optical degradation of the strip material due to heat. An optical portion is formed by the base portion 24 of each pocket 12 by restraining the base portion by clamping or other forming techniques during the pocket forming operation to avoid stretching or other deformation thereof which would be detrimental to its optical performance. In this manner essentially all stretching of the material during forming ^' is limited to the portions forming the side walls 14 of the pockets (which eventually form the end walls of the

resulting cuvettes-Figure 9) and the optical portions 24 are maintained stress-free and with a uniform thickness.

During forming, a series of regularly spaced indexing perforations 30 can be formed along opposite longitudinal edges 21 of the strip material. These perforations 30 are utilized in the clinical analyzer to precisely to control the transport of the cuvette belts through the analyzer. The perforations are also used in the apparatus of this invention for driving the formed strips therethrough for subsequent processing and in particular for accurately aligning the strips when they are brought together in precise registration prior to joining the strips together at the sealing station 104 in the manner explained below.

During transport of a cuvette belt 22 through a clinical analyzer as aforesaid, the cuvettes are aligned with various processing stations including one or more photoanalysis stations. During such photoanalysis it is important that the optical window of the cuvette, i.e. that portion viewed by the analysis instrument, be accurately aligned with the analysis station. For this reason it is important to

maintain a precise relationship between the indexing perforations and the optical windows of the cuvettes and accordingly the edges of the strip may, like the base portions of the pockets, be clamped during the forming process. In a preferred embodiment, the optical windows are those parts of the optical portion 24 which are located at opposite ends of the pocket 12 in order to insure to the greatest ^' possible extent that the aforesaid precise alignment is repeatedly maintained during transport bf the cuvette belt 22 through the analyzer.

Af.ter formation of the. pockets 12, the two strips 20 are brought together in face-to-face relationship as shown in Figures 4 and 5 with the pockets 12 and perforations 30 in precise registration and so that the pairs of opposing pockets 12 together form closed chambers 18. The registered strips are then heat sealed together to form a composite strip 40 defining two integral side-by-side mirror image cuvette belts joined together by their mouth or open ends.

If the two strips 20 are formed in mirror image relation with their open pockets 12 facing each other, they can straightforwardly be brought together

in the appropriate face-to-face relation. However, as explained below, it is preferred to form the strips one above or adjacent the other with their open faces both directed downwardly, in which event the lower strip must be twisted through 180° about its longitudinal axis prior to bringing the strips together.

It has been found that the formed strips 20 may be joined together by a heat sealing process at relatively low temperature if a laminate material such as SURLYN is utilized, or by impulse bonding techniques if higher melting point materials are utilized. It is also possible to utilize other joining methods, such as adhesive bonding, as long as the optical characteristics and dimensional tolerances of the cuvettes 22 are not adversely affected thereby.

Following the heat sealing step, the composite strip 40 is advanced to a slitter 106 where it is divided longitudinally down its centerline A (indicated for the composite strip 40 in Figure 5 and for the single strip 20 in Figure 2) to separate the two cuvette belts 22. The two completed cuvette belts 22 are each as shown in Figures 6 - 9 and comprise a series of open-topped chambers 17 separated by thin

webs 19 and having a web-like transport area 28 along its lower edge having the indexing perforations 30 formed therein.

As seen particularly in Figure 9, the cuvettes are generally rectangular in cross-section and, in order to provide a precise optical path, the side walls (formed by the base portions 24 of the pockets) are made parallel. Instead of being parallel, optionally the side walls 22 may be deliberately given some other shape as such a convex or outwardlycurved profile and the precise optical path length achieved-by passing the cuvettes between glass plates spaced so as to flatten the side walls into parallel relationship with the optical analysis station of the clinical analyzer in the manner described in commonly owned copending US Patent Application Serial No. 746,233, filed 6/18/85 , entitled "Cuvette Belts and Manufactureof Same", the disclosure of which is hereby incorporated by reference in its entirety herein.

One specific embodiment of cuvette belt making apparatus of this invention will now be described in detail with particular reference to

Figures 10 and 11. In this embodiment, two strips 20a, 20b of plastic material are advanced through an in-line series 100 of processing stations to produce simultaneously two cuvette belts 10. The two strips 20 are initially advanced to respective forming presses at a forming station 102 where they each have a series of shallow transverse pockets impressed therein.

The pocketed or formed strips 20 are then brought together in alignment at a heat sealing station 104 where they are joined together to form a composite strip 40 defining two integral cuvette belts, which are then separated at a slitting station 106. The two cuvette belts 22a, 22b so formed may then advanced through two inspection stations 108,110 to check the cuvettes for defects and to a counting and cutting station 112 from which they are wound onto spools at the spooling station 114.

In accordance with the embodiment shown, the strips are indexed stepwise through the forming presses 102, the heat sealer 104 and the inspection stations 108, 110 while being advanced in continuous motion through the slitting station 106 and the countingand cutting station 112. Of course,the

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inspection stations may be located at any convenient location in the process. The spools 116 on which the cuvette belts 22 are wound at the spooling station 114 operate intermittently. The plastic strips 20a, 20b can be composed of any suitable material such as a laminate of KODAR brand polyester resin and SURLYN brand ionomer resin as described above. Strips 20a, 20b are advanced from respective motor driven supply reels 118a, 118b via dancer rolls 120a, 120b to respective forming presses 122, 124. Each forming press 122, 124 has dies arranged to form several pockets at a time in the associated stock strip 20, and the strips 20 are advanced by corresponding amounts for this purpose between each pressing operation by an indexing drive 126 or 128. At the same time as impressing the transverse pockets 12 in the plastic strips, the forming dies produce indexing perforations -30 along each of the edges 21 of the strips in the manner previously described.

The indexing perforations 30 are utilized in subsequent drives through the cuvette belt making apparatus 100 described herein in order to accurately

control the advancing movements of the plastic strips 20 therethrough. The drives 126 and 128 are tractor drives and each comprise a pair of tractor, drive rolls 130 positioned along respective side edges of the strip with the strip being held in engagement with the drive rolls 130 by a reaction belt 132 which passes over guide rollers 133. Operation of the tractor drives 126 and 128 is timed in relation to the operation of the forming press so that the advancing movement of the strips 20 is effected between the forming operations while the forming pressed are open.

Further, in order to insure proper spacing of the indexing perforations 30 and pockets 12 between one group and the next, it is important that the advancing movement of each strip by the associated tractor 126, 128 be closely and accurately controlled so as to produce exactitude of strip advance in a repetitive manner. To this end the operating cycle of the tractor drives can be controlled by a timing mechanism, suitably a cam control mechanism such as a geneva mechanism.

The forming presses 122, 124 suitably employ cold forming techniques and although no heat formation.

per se, is util ized, a sl ight temperature el evation below the transition temperature of the strip material is required to avoid tears in the plastic strips. To „ this end the temperature of the dies is suitably el evated to s l i ghtly in excess of 100°F. In a preferred embodiment the process forms eight pockets at a time and has about a f ive second cycl e with the die temperature being approximately 113°F.

Immediately ahead of each forming process is arranged a cleaning and static el iminator station 134, 136 f or each of the strips. These are pref erably ionized air cleaning systems. Alternatively, suitabl e cl eaning systems such as those manufactured by 3M Company of Minneapol is, Minnesota which employ cleaning tapes 138 pass over grounded bars 139 between which the strip is passed. The strips 20 are guided at each side of the cl eaning subsystem by idl er rol l s 140 and 142 and the strips are advanced stepwise through the respective cl eaning subsystems by the associated forming press tractor drive 126 or 128.

A spl i cing station 144 or 146 can be provided between each supply reel 118 and the associated dancer roll 120 for splicing together the lead and trail edges

of two strips 20 when a new supply reel is inserted.

Following forming, the two strips are advanced through respective static eliminator- stations 148, 150 in which ionized air is blown against the formed ^" strips to deionize them, following which the two strips are brought together at a point 152. Following careful alignment they are sealed together in a heat sealer 154. In order to hold the formed strips 20 stationary for heat sealing they are indexed stepwise through the heat sealer which operates on a length of strip corresponding to- several pockets at a time. Preferably, in order to match its operating cycle to that of the associated forming presses 122, 124, the heat sealer 154 is arranged to seal the same number of pockets at a time that are formed during each pressing operation. Thus in this case, the heat sealer seals a length corresponding to eight cuvette pockets at a time.

The indexing drive of the strips 20 through the heat sealer 154 is effected by a tractor drive 156 arranged immediately downstream from the heat sealer. Like the tractor drives 126, 128, this drive comprises a pair of tractor drive rolls 130 and associated

reaction belt 132. While the strip movements through the forming process and heat sealer are preferably coordinated, variations in strip movements between the tractor drives 156 and the tractor drives 126, 128 are accommodated by suitable means as will now be described.

In the case of the upper strip 20a, the tractor drive 156 advances the strip through both the static eliminator 148 and the heat sealer 154 with strip movement variations accommodated by a tension roller 158 between the tractor drive 126 and static eliminator 148. Tension control for the lower strip 20b, however, is somewhat different due to the fact that the lower strip is twisted through 180° during its passage between the static eliminator 150 and the point 152 at which the strips are brought together.

This twisting action of the strip 20b is required in this embodiment because both the upper and lower strips are formed in the same attitude, that is to say, with the pocket impressed upwardly through the strip. In order to avoid tension on the lower strip while it is being twisted, a tractor drive 160 (like the above described tractor drives) is provided

following the static eliminator 150 and the strip 20b is formed in a free loop LI approximately nine inches wide between the tractor drive 160 and the meeting point 152. A tension roller 162, like the tension roller

158 for the upper strip 20a, accommodates variations between the tractor drives 128 and 160 before and after the static eliminator 150. Between this tension roller

• 162 and the static eliminator 150, the lower strip 20b passes over an idler roll 164. Idler rolls 166 are provided at each side of the upper static eliminator 148.

In order to provide for accurate alignment of the formed strips 20 prior to sealing them together in the heat sealer 154, the following arrangement is provided. At the meeting point 152 of the two strips, a tensioning of the strips passing into the heat sealer is produced. This is achieved by a tensioner (s) 167 consisting of a pair of tensioning tractor rollers 168 over which both strips 20 are passed and held there around by a reaction belt 170 passing over guide rollers 171, the tractor roller 168 being connected to a torque motor. Between the tensioning roller 168 and

the heat sealer 154, the strips are separated over tension control rollers 172 and final alignment in the heat sealer is achieved by the strips en-gaging on tapered pins at the heat sealer. The composite strip 40 formed by the joining together of the two strips in the heat sealer essentially comprises two integral, side-by-side, mirror image cuvette belts joined at the mouths of the cuvettes. In order to divide the composite strip 40 into separate halves to form the completed cuvette belts 22, the composite strip is now advanced to the slitter station 106.

Composite strip 40 is advanced in continuous motion through the slitter 174 by means of a continuously operating tractor drive 176 which consists of a tractor drive roller 178 and associated reaction belt 180 entrained over guide rollers 181. In order to accommodate the variations in the strip movement between the indexing drive 156 of the heat sealer 154 and the continuous drive 176 of the slitter 174, a free loop L2 of composite strip approximately 12 inches wide is provided between the indexing tractor drive 156 of the heat sealer 154 and a torque-controlled tensioner

182 provided at the input of the slitter. This tensioner 182, like the tensioner 167, consists of a pair of tractor rollers 168 connected to a torque motor and having a reaction belt 170 entrained over guide pulleys.

The slitter 154 itself consists of a continuously rotating endless band blade aligned with the center of the composite strip so as to divide the strip into two symmetrical parts along the center line, each of which parts comprises a complete cuvette belt 22. So as to remove any debris from the slitting operation, a vacuum system is associated with the cutting blade.

In order to assist the cutting operation, the separated strip portions 22 are pulled apart downstream of the slitter 154 as shown in Figure 11 to produce lateral tension on the lateral strip as it goes through the slitter. This is achieved by the positioning of the elements of the continuous tractor drive 176 and in particular by the spacing apart of the tractor rolls which engage the respective row of indexing perforations.

Following separation, the two cuvette belts

are passed side-by-side through the further stations which will now be described at which the same operations are performed on both belts simultaneously.

For convenience of description the movements of one belt only will be described, it being understood that those of the other belt are identical.

From the slitter 154, each cuvette belt passes through individual inspection station 108 which incorporates a static eliminator 184 ahead of the operator location 186. In order to permit an operator to clearly inspect the cuvettes 22 they are held stationary for a fixed time period at the inspection station and to this end an indexing drive 188 (tractor rollers 130, reaction belt 132) is provided for advancing the cuvettes in steps through the visual inspection station 108. For controlling the belts a tensioner 190 (torque controlled tractor rollers 168, reaction belt 169) is arranged at the input to station 108 and a free loop L3 of belt about 12 inches wide is arranged between the tractor drive 176 of the slitter 154 and tensioner 190. Should the operator see a faulty cuvette or section of cuvette belt he will mark the belt appropriately with a machine readable or

visual mark.

Following visual inspection, the belts are passed to a second inspection station or test station 110 at which there is provided a high voltage leak detector 192 of faulty seal detector. Also provided at this station is an automatic marker 194 for marking defective cuvettes or portions of belt according to the test provided by the high voltage leak detector.

The belt is driven through this portion of the inspection area separately from the visual inspection station by a further indexing drive 196 and a' free loop L4 suitably about 12 inches wide is provided between the two stations. This is done to allow an operator to retain a section of belt in the visual inspection station 10.8 for longer than one index cycle. Thus it will be understood that the timing of the operation of the indexer 188 is under control of the operator. As in the visual inspection station 108 a tensioner 198 connected to a torque motor controls the belt tension in the test station 110.

The high voltage leak detector 192 consists essentially of a series of biased conductive probes which are inserted into successive groups of cuvettes

as they are aligned with the probes by the indexing system 196. Such a detector is described in detail in commonly owned copending U.S. Patent Application_Serial No 746,172 filed 6/18/85 , and entitled "Cuvette Belt Faulty Seal Detector"

, the disclosure of which is hereby incorporated by reference in its entirely herein.

Following the high voltage leak detector is arranged the automatic marking device 192 which, in the event the leak detector should detect a faulty cuvette, will mark the individual cuvette or a section of cuvette belt accordingly.

It will be understood that following its passage through the inspection stations 108 and 110 a cuvette belt may have received one or more markings of a faulty, cuvette or belt section. The belt is now passed through the cutting station 112 for cutting out the faulty sections of belts. In addition to a cutter 202, there is incorporated at the cutter station a photodetector 204 for detecting the markings applied to faulty cuvettes. The cuvette belt is driven in continuous motion through the cutter station 112 as will be described below. A counter 206 for counting

the number of cuvettes passing is also provided ahead of the detector 204.

In the event that the photodetector 204 detects a marking indicitive of a faulty cuvette, the cuvette is operated automatically to sever the belt immediately ahead of the faulty portion. The photodetector now examines the next seven cuvettes. If these are found to be good it will ^" then cut the belt again after seven cuvettes and the faulty portion can be discarded. If however a further faulty cuvette is found it will continue looking until it sees seven good cuvettes in a row before effecting the second cut.

Because of the presence of the cutter 202 at

» this station it is not possible to insure belt (22) passage through the station by means of a downstream tractor drive and to this end a tractor drive 210 is arranged ahead of the cutter 202. This consists of a continuously operated tractor belt 212 passing over a drive roller 214 and idler rollers 216. In order to avoid interference between the continuous motion of the belt 22 through the cutter 202 and its indexing motion throug the previous indexing stations 110, a free loop L5 of belt about 12 inches wide is provided between the

indexing drive 196 and an idler roll 218 arranged immediately ahead of the continuous drive 210 of the cutter station 112.

From the cutter 202, the belt passes to a motor driven spool 116 via a tensioning roller 220 from an idler roller 222 arranged beyond the end of the cutter station. The tensioning roller 220 is arranged to dance in accordance with the tension applied by the spool as it winds up the belt. As it moves, the tension roller with operate a start switch or a stop switch for the spool so that the latter is intermittently driven to insure that the belt is wound evenly thereon. If a cut is made, the operator may have to guide the new loading edge formed by the cut onto the spool.

The counter 206 counts the number of cuvettes and signals the cutter 202 to operate to cut the cuvette belt when it has counted a number of cuvette belts equal to the capacity of the spool. It will also activate a warning to alert the operator to check and change the spool. Suitably, the spool has a capacity of belt length equivalent to 2000 cuvettes.

For setting up the apparatus 100, the lead end

of each strip is provided with an 18 inch long leader provided with indexing holes. Taking the upper strip 20a first, this is threaded over the dancer roll 120a, through the cleaning subsystem 134 and the forming press 122 onto the indexing drive 126. Similarly the lower strip 120b is threaded over dancer roll 120b through the cleaning subsystem 136 and the forming press 124 onto the indexing drive 128.

The apparatus is now set in motion and as the leaders are advanced they are successively threaded through the various stations and engaged with successive ^' drives as the apparatus is operated until finally the leaders reach the collection spools and are attached thereto. From then on the apparatus can be operated without operator involvement. It should be realized that in setting up the machine the operator introduces the various free loops at the appropriate locations and also induces the 180° twist in the lower strip before it reaches the meeting point 152. From the foregoing it will be realized that the plastic strips 20a and 20b from which the cuvette belt 22a and 22b are formed are advanced through the apparatus variously in stepwise and continuous modes.

Thus, taking the major elements of the apparatus the strips are advanced stepwise through the forming process 122, 124 and the heat sealer 154, in continuous motion through the slitter 174, stepwise through each of the inspection and test stations 108, 110 and continuously through the counting and cutting station 112, being wound intermittently on the collection spools 116.

This unique strip processing arrangement permits the production of continuous cuvette belts on an uninterrupted production basis without operator involvement in a single in-line operation. In particular, the batch indexing mode enables forming and sealing to be effected on the stationary strips while permitting continuous operation of the slitter so that a clean uninterrupted division of the composite strip into the component cuvette belts can be achieved. By this mixing of continuous and batch indexing modes a particularly compact and well organized production line can be achieved.

An embodiment of heat sealing station particularly suitable for use at the sealing station 104 is disclosed in commonly owned U.S. Patent

Application Serial No. 746,232 filed 6/18/85 , and entitled "Heat Sealing Method and Apparatus", thedisclosure of which is hereby incorporated by reference in its entirely herein.

Although particular configurations of the present invention have been discussed in connection with the above described preferred embodiments thereof it should be understood that those skilled in the art may make various changes, modifications and substitutions thereto without departing from the spirit and scope of invention as defined in the appended claims.

Thus, in a modification of the manufacturing line described above only a- single forming is utilized and the slitting station is arranged ahead of the sealing station. Such an arrangement is for making a cuvette belt according to the process described in our aforesaid copending application No. 284,842 in which a single strip is formed with the transverse pockets, slit down the middle to produce to separate mirror image belt halves and the two halves joined together. In this arrangement the sealing station is adapted to

operate on separated bel t halves and guide means is prov ided for reorienting the bel t hal ves- fol lowing slitting from their side-by-side relation to bring them into face-to-face relation at the sealing station. ^'