EP0192571A2 - Test tubes support for a centrifuge, and its manufacturing method - Google Patents

Abstract

1. A carrier of the type comprising a plurality of stocked plates which are provided with holes and which are angularly oriented in such a way that their respective holes (40) are in mutual alignment, thus forming housings for receiving tubes (22), said plates being mounted slidably on two parallel arms of a U-shaped support ; said support (24) comprises a base portion (28) with a surface substantially equal to that of the plates (26) and two slide portions (30, 32) which are produced in one piece with the base portion and which are received in axial recesses (36, 38) formed at diametrally opposed positions on the edges of the plates, said slide portions being provided on their face which is inward with respect to the support, above the upper plate, with abutments (42) intended to prevent withdrawal of the plates or insertion of other plates into the support.

Description

From US Pat. No. 4,032,066, a centrifuge rotor is known for the centrifugation of samples contained in test tubes. This rotor comprises several arms spaced radially and forming between them intervals in which nacelles are mounted so as to be able to pivot on said arms.

Each of said nacelles is in the form of a cylindrical tank and receives a stack of plates of diameter substantially equal to the internal diameter of the tank, and which are pierced with holes for the introduction of test tubes. Said plates can be moved in a block and maintained in a predetermined orientation such that their holes are respectively in alignment with each other, by means of a U-shaped holding element, the central branch of which supports the stack of plates and whose vertical arms are received in diametrically opposite notches, formed in the edge of the plates. At the base of the stack of plates is a support plate on which the bottom of the test tubes rests.

The user can thus make a custom rack height close to that of the tubes used, by threading on the branches of the holding element, the support plate and the desired number of plates so that the stack has the desired height. All of the plates can then be transported as a whole by means of the holding element and inserted inside the tank.

However, the realization of such a rack where the plates are removable and can be added as desired by the user, can cause a serious drawback for the operation of the centrifuge. It may indeed happen that, inadvertently, one or more additional plates are introduced into the rack or, on the contrary, one or more plates are removed therefrom. If racks with the same number of plates are loaded in the centrifuge, the rotor will be unbalanced and will cause vibration intense centrifuge.

On the other hand, in some racks it may be necessary to use different plates and stack them in a very precise order. For example, a rubber wafer is sometimes used which is placed above the stack of plates and whose holes have a diameter slightly smaller than that of the holes in the plates. The role of this wafer is to enclose the tubes at their upper part and to keep them in place in the rack. When, after centrifuging, the rack is turned over to empty the tubes of their contents, the latter are prevented from falling by the rubber wafer which encloses them.

In other cases, it happens that an additional wafer of small thickness and diameter smaller than that of the other plates is used, which serves to adapt in the rack a type of tubes which must not rest on the bottom of the rack.

These two examples show the importance of respecting the stacking order of the plates and pancakes and not to forget them. It goes without saying that if the plates and pancakes are removable and are stacked by an operator, errors in stacking or oversights become possible, with serious consequences, such as for example the fall of the tubes in the first example cited, or the deterioration of the tubes in the second example.

The present invention aims to remedy this drawback of racks of the known prior art, and for this purpose relates to a rack of the type comprising several stacked plates, pierced with holes and oriented angularly so that their respective holes are in alignment with each other. others, thus forming housings for receiving the tubes, said plates being slidably mounted on two parallel arms of a U-shaped support, characterized in that said support comprises a sole surface substantially equal to that of the plates and two slides coming from manufacturing with the sole, and which are received in axial notches, formed in diametrically opposite positions on the edges of the stacked plates, said slides being provided on their inner face at support, above the upper plate, stops intended to prevent the withdrawal of the plates or the insertion of other plates in the support.

In an advantageous embodiment of the invention, the stops are formed by local deformation of said slides. The support can for example be produced by molding a thermoplastic material and the stops produced by melting the material at the point where the stops are to be formed. But it goes without saying that the support can also be made of metal, the stops then being stamped.

The stops can also be formed by attachments on the slides. In a particular embodiment, the stops are constituted by grooved nails fixed on the slides and the point of which protrudes from the inner face of the latter.

Advantageously, the slides and the notches have dovetail sections of complementary shapes. Thus, the plates cannot be removed from the support while attempting to separate the slides from one another since the dovetail assembly is opposed to it.

Since the number of plates cannot be modified, it is advisable to make several racks carrying different numbers of plates and intended to receive tubes of different heights.

The invention also relates to a method of producing the rack. This process consists in threading a number of plates such as the height of the plate stack is less than the height of the tubes to be centrifuged, then to form the stops on said slides.

• La figure 1 est une vue en plan d'un rotor en étoile du type à nacelles, deux nacelles seulement étant représentées pour la clarté du dessin ;
• La figure 2 est une vue en perspective d'un portoir, la nacelle n'étant pas représentée ;
• La figure 3 est une vue en perspective du portoir, les plaques occupant une position différente ;
• La figure 4 est une vue en coupe suivant la ligne IV-IV de la figure 2 et montrant une première forme de réalisation des butées ;
• Les figures 5 et 6 sont des vues en perspective de deux éléments constituant le portoir, et
• La figure 7 est une vue analogue à la figure 4 et montrant une autre forme de réalisation des butées.

An embodiment of the invention will now be described with reference to the accompanying drawings in which:

• Figure 1 is a plan view of a star rotor of the nacelle type, only two nacelles being shown for clarity of the drawing;
• Figure 2 is a perspective view of a rack, the nacelle not being shown;
• Figure 3 is a perspective view of the rack, the plates occupying a different position;
• Figure 4 is a sectional view along line IV-IV of Figure 2 and showing a first embodiment of the stops;
• FIGS. 5 and 6 are perspective views of two elements constituting the rack, and
• Figure 7 is a view similar to Figure 4 and showing another embodiment of the stops.

With reference to FIG. 1, a centrifuge rotor 10 is mounted rotating around an axis 12. The rotor is of the star type and comprises several radial arms 14 defining between them intervals in which are arranged nacelles 16 in the form of cylindrical tank. In a manner known per se, each nacelle is pivotally mounted on the arms which enclose it around pivots 18, so that when the rotor 10 is at rest, the nacelle takes the position shown in solid lines in FIG. 1, and when the rotor turns, it pivots towards the position shown in dashed lines.

In each nacelle is inserted a rack 20 for test tubes 22 which is shown in detail in FIGS. 2 to 4. The rack comprises a support 24 intended to receive a plurality of stacked plates 26. The support comprises a substantially flat sole 28, of diameter equal to the inside diameter of the nacelle 16.

At two diametrically opposite points of said bottom stand above the latter, two runners 30, 32 whose outer profile remains within the limit defined by the side wall of the bottom.

The slides can come from manufacturing with the sole 28 or be produced separately and attached to the latter by any known means, for example by welding, gluing, or screwing. In a preferred embodiment, the sole and the slides are obtained by molding a plastic material.

The sole has on its upper face a series of substantially hemispherical holes 33, intended to receive the lower end of the test tubes.

In another embodiment known per se, the upper face of the sole can be covered with a plate of elastically deformable material, for example rubber. In either case, the tubes have non-punctual contact with the soleplate, which makes it possible to reduce the stresses on the tubes during the rotation of the rotor and consequently achieve much higher rotor rotation speeds. in case the contact is punctual.

In FIGS. 2 to 5, the slides are flat and have a dovetail cross section which widens towards the inside of the support. The slides are long enough that, when the sole 28 of the support rests on the bottom of the nacelle 16, the upper ends of the slides arrive slightly above the level of the upper edge of the nacelle. Said ends are curved outward to form portions 34 allowing the establishment and removal of said racks.

The plates 26 have a cylindrical side wall with a diameter equal to that of the sole. As shown in the figure 6, they have, at two diametrically opposite points on said side wall, two axial notches 36, 38 in the form of a dovetail, of cross section complementary to that of the slides 30, 32.

The plates are pierced with a plurality of axial holes 40 of diameter slightly greater than the external diameter of the test tubes 22. These holes are arranged on each plate in the same way with respect to the notches 36, 38. It follows that when several plates are threaded on the slides, their respective holes come into alignment with each other, thus forming a cylindrical housing in which a test tube 22 can be inserted. The number of plates stacked on the sole 28 is chosen so that the total height of the stack is less than the height of the test tubes.

According to the invention, the slides 30, 32 are provided with stops 42 intended to oppose the withdrawal of the plates upwards, without however preventing their sliding movement along the slides. For this purpose, the stops are arranged widely above the highest plate of the stack, for example in the vicinity of the upper ends of the slides. They can be produced by any known means, for example, as in the case illustrated in FIGS. 2 to 5, by locally deforming hot the plastic material of the slides, so as to reveal the stops on the internal face of the slides.

In the embodiment of Figure 7, the stops are constituted by grooved nails 44 fixed through the wall of the slides and whose tip protrudes from the internal face of the latter.

By sliding the plates 26 upwards, as shown in FIG. 3, it becomes possible to clean the faces as well as the holes of the plates.

To allow observation of the test tubes in place in the rack, without having to remove or lift the plates, each of the latter has on its underside at least one groove 46. The contents of the tubes can be observed through the grooves. The latter also have the role of allowing better stability of the plates. It is in fact understood that it is simpler to obtain good contact of a plate on the plate situated below it when the contact surface is reduced to that of the projecting portions 48 defined on either side. bleeding.

It goes without saying that modifications of detail can be made to the embodiment described without departing from the scope of the invention. For example, the slides 30, 32, the notches 36, can have any other shape of section which opposes the withdrawal of the plates by spacing the slides.

Claims (8)

1.- Rack of the type comprising several stacked plates, pierced with holes and angularly oriented so that their respective holes (40) are in alignment with each other, thus forming housings for the reception of tubes (22), said plates being slidably mounted on two parallel arms of a U-shaped support, characterized in that said support (24) comprises a sole (28) with a surface substantially equal to that of the plates (26) and two slides (3 ₀ , 32) coming from manufacture with the sole and which are received in axial notches (36, 38), formed in diametrically opposite positions on the edges of the plates, said slides being provided on their inner face to the support, above the upper plate, stops (42) intended to prevent the withdrawal of the plates or the insertion of other plates in the support. 2.- Rack according to claim 1, characterized in that the stops (42) are arranged clearly above the upper plate. 3.- Rack according to one of claims 1 and 2, characterized in that the stops (42) are formed by local deformation of said slides (30, 32). 4.- Rack according to one of claims 1 and 2, characterized in that the stops are constituted by parts attached to the slides. 5. Rack according to claim 4, characterized in that said inserts are constituted by grooved nails (44) fixed on the slides and whose point protrudes from the inner face of the latter. 6. Rack according to one of the preceding claims, characterized in that the slides (30, 32) and the notches (36, 38) have complementary sections preventing the slides from being separated from one another, by example in dovetail. 7. Rack according to one of the preceding claims, characterized in that the plates (26) are provided on their underside with at least one groove (46) allowing observation of the test tubes (22). 8.- A method of producing the rack according to one of the preceding claims, characterized in that it consists of threading on the slides (30, 32) of the support a number of plates (26) such as the height of the stack of plate is slightly less than the height of the tubes (22) to be centrifuged, then to form the stops (42) on said slides.

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