CHUCK DEVICE FOR HOLDING A CELL FOR THE CENTRIFUGATION OF BLOOD, AND THE LIKE

Abstract: The chuck device comprises clamp elements (4,5,6) having, at one end, an underlying tooth (8) and a conical surface (7) conjugated with the surface of the cell (2); the clamp elements (4,5,6) are uniformly distributed on the circumference of a plate (3), comprising a surface (3a) for the resting of the bottom (2a) of the cell (2), to which they are pivoted so as to be rotatable in radial planes, means (14) being present for locking the clamp element (4,5,6) in the closure position.

Description: The invention relates to a chuck device for holding or fastening thereon a cell for the centrifugation of blood, and the like. It is known that the centrifugal separation of blood components such as plasma, red and white blood corpuscles and platelets is performed in cells essentially constituted by a rotating container and a stationary coupling whereto are connected ducts for the inflow of the blood and the outflow of the separated component intended to be collected. The container comprises an external bell-shaped envelope, normally made of plastics and downwardly closed by a bottom welded thereto, which is caused to rotate by being fixed to a chuck connected to a rotating shaft. Known chucks, however, have some disadvantageous characteristics, the most evident whereof resides in the fact that they are provided with elements for gripping the cell having such a configuration as to exert exclusively radial thrusts: as a consequence of this, inner tensions are developed in the region proximate to the bottom of the container, and more precisely at the welding of said bottom to the bell-shaped envelope, where the maximum stress occurs as a combined effect of the centrifugal force and of the hydrodynamic thrust exerted by the flow of incoming blood; these inner tensions can be so strong as to possibly cause the breakage of the cell, with easily imaginable consequences. US-A-2 461 674 shows a centrifuge-vessel having a bottom provided with a laterally extending peripheral flange having circumferentially spaced slots. The vessel is fastened to a rotary plate by means of bolts inserted through the slots of the vessel peripheral flange. The device therefore provides axial gripping thrusts, however the disadvantage of high inner tensions still exists in the region proximate to the vessel bottom due to the fact that the gripping force distribution is concentrated at the vessel flange slots. What has been described above with reference to the centrifugal separation of blood components is not exclusive to this field, similar problems also occurring in many other fields. The aim of the present invention is to provide a chuck device for fastening thereon a cell for the centrifugation of blood and the like such as to firmly lock the cell, preventing it from being damaged even with very high rotation speeds. Within the scope of the proposed aim, an object of the invention is to provide a chuck wherein the gripping elements for the cell are easily operated. The proposed aim, as well as the object mentioned, are achieved by a chuck device as defined in claim 1. Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment of the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein: figure 1 is a top view of the invention with the jaw elements in closure position and in the absence of the cell; figure 2 is a view partly in section, in slightly enlarged scale, along the broken line II-II of figure 1, of the chuck device supporting a cell shown in phantom lines; figure 3 is a sectional view of the jaw element visible in figure 2 in opening position. With reference to the above described figures, the numeral 1 generally indicates the chuck device for fastening a cell for the centrifugation of blood materialized by the container body 2 thereof, which is intended to rest, in the locked position, with the bottom 2a on the surface 3a of a circular-crown provided on a plate member 3. The chuck device 1 comprises the plate member 3, preferably made of metallic material such as an aluminium alloy and adapted to be rotated by a rotating shaft (not shown) coaxial with the plate 3 and fixed to the plate 3 by means of joints provided on the end of the shaft and screws inserted in holes 3b. The chuck also comprises clamp or jaw elements 4, 5, 6 uniformly distributed on the circumference of the plate for fastening the cell container 2 thereon; these elements are made of plastic material to reduce the amount of rotating mass, and have such a circumferential extension that the contact thereof with the cell container 2 occurs, in the manner described hereinafter, substantially continuously, i.e. smoothly, without jerks. Preferably, said jaw elements 4, 5, 6 are identical, and only the one indicated at 4 is therefore described in detail. Said jaw element 4 is provided, at one internally facing end, with a conical surface 7 which is intended to make contact and engage with the surface of the cell container 2 when the same rests with the bottom on the circular crown 3a, the conical surface 7 being shaped according to the surface of the cell 2. For the purpose the conical surface 7 is recess shaped near the plate member 3. The clamp element 4 is provided furthermore with a tooth 8 having a reduced circumferential extension limited to the central region of the surface 7; this tooth 8, the function whereof is explained hereinafter, is adapted to be inserted, when the element 4 is in the closure position as indicated in figure 2, in a recess 3c provided on the crown 3a of the plate 3 to create a depression in a limited region of the circular-crown surface 3a for allowing the bottom 2a of the cell to rest thereon. In the same manner the teeth of the clamp or jaw elements 5 and 6, not shown in the drawing, are adapted to be inserted in the recesses respectively 3d and 3e. The jaw element 4 is pivoted with respect to the plate 3 so as to be rotatable in a radial plane between the opening position visible in figure 3, determined by the resting of the tapered surface 9 thereof on the upper surface of the plate 3, and the closure position visible in figure 2. The element 4 is in fact associated with the pivot 10 supported by the studs 11a and 11b which are rigidly associated with the plate 3 by having a threaded stem thereof inserted in a hole of said plate, and subsequently tightened by a nut 12. A helical spring 13 is coiled on the central part of the pivot 10 and has its ends in contact respectively with the plate 3 and with the element 4, and biases the clamp or jaw element 4 in the opening position shown in figure 3. The locking means, that keep the clamp or jaw element 4 in the closure position, comprises the screw 14, housed in a bush 15 and having a square actuation stem 14a, which is adapted to engage with the female thread 16 provided in the bush 16a rigidly associated with the plate 3; by tightening the screw 14 a spring 15a is loaded, the spring having the function of moving the screw upwards, as soon as the latter disengages itself from the threads of the female thread 16 in the opening step, to the position shown in figure 3, thus achieving the double purpose of preventing any hindrance in the closure movement of the element 4, any possible jamming of the screw 14 on the plate 3 being prevented, and of having the stem 14a popping out from the upper surface of the element 4 so as to constitute a signal which makes evident for the operator that the screw 14 is not screwed-on. The operation of the invention is extremely simple: with the clamp or jaw elements 4, 5, 6 open, that is to say in the position indicated for the element 4 in figure 3, a container cell 2 preferably is moved in the axial direction towards the chuck, and in the last steps of the approaching movement the bottom 2a of the former gets in contact with the teeth 8 of said elements 4, 5, 6 causing the lowering thereof towards the closure position, overcoming the action of the springs 13. In fact, the jaws or clamps 4,5,6 are arranged on a common circumference and are so designed and dimensioned that the internally facing tips of the teeth 8 of the jaws 4,5,6 lie on a circumference the diameter of which is slightly smaller than the external diameter of the bottom 2a of the cell 2. When the cell container 2 reaches the position in which the bottom 2a rests on the surface 3a, the elements 4, 5, 6 achieve the closure position visible in figure 2, the respective conical surfaces being in contact with and mating the external surface of the cell container 2; the teeth 8 have, in this condition, fully inserted themselves inside the recesses 3c, 3d, 3e respectively, so as not to affect the optimum condition of resting of the bottom 2a on the surface 3a. It will be understood that, according to a modified embodiment, one or even two of the jaw elements of simplified shape may be stationary, i.e. not swingable and only one of the jaws, swingable. In such case, che cell container will be first inserted into the fixed jaw members in an inclined condition, and will then be swinged to engage the swingable jaw and entrain it in its closing position. The locking in closure position of the elements 4, 5, 6 is performed by an operator by actuating one after the other the screws 14 present on each thereof and the fastening of the cell container 2 which has been effected in this manner is such as to offer the greatest assurances since on said cell, besides the radial thrust, a thrust directed along the axis of rotation is also simultaneously determined, and these thrusts are applied in the region of maximum stress so as to also effectively collaborate to the resistance thereto. The described invention is susceptible to numerous modifications and variations. For example, the mutual position of the jaw members 4,5,6 may be made adjustable to change the diameter of the circumference on which the jaw members lie. This may be done for instance by either providing the jaw members with a composite structure and rendering the grasping part of the jaw member radially expandable or retractable or by providing the plate member 3 with a composite structure which may be radially expanded or retracted to position the unit including the studs 11 and the bush 16a nearer to or further from the axis of rotation of the chucks. Furthermore, the pivot 10 may be arranged upwardly off set with respect to the circular crown 3a, so that the radially directed forces passing underneath the pivot 10 and generated during the clamping action may create a rotating moment in the closing direction of the jaw members to press the body 2 against the plate 3 even in lieu of the locking means. Moreover, all the details may be replaced with other technically equivalent elements. In the practical embodiment of the invention, the materials employed, as well as the shapes and dimensions, may be any. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: A chuck device for holding a body, in particular a body portion (2) of a cell for the centrifugation of blood and the like, comprising a supporting member (3) defining an axis of rotation of the chuck device and jaw members (4, 5, 6) supported on said supporting member, said jaw members being arranged at a distance around said axis of rotation for holding said body therebetween, characterized in that at least one of said jaw members (4, 5, 6) is supported on said supporting member (3) pivotally about a pivot axis (10) extending transverse to said axis of rotation to allow swinging of said jaw member from a closing position into an opening position and vice versa. A chuck device according to claim 1, wherein said jaw member is spring (13) biased into said opening position. A chuck according to claims 1, 2, wherein said jaw member has an inwardly facing engaging surface portion (7) for mating engagement with said body portion (2),said engaging surface portion (7) being conical and divergent in the direction towards said supporting member (3), and has a recessed portion between said surface portion (7) and said supporting member (3). A chuck device according to claims 1-3, wherein said jaw members (4, 5 and 6 ) are made of plastics. A chuck according to claims 1-4, wherein said jaw member has a tooth formation (8) inwardly and radially projecting therefrom. A chuck member according to claim 5, wherein said jaw members are at least three in number and are generally arranged along a generic circumference concentric with said axis of rotation and wherein said inwardly facing engaging surface portion (7) has an upper edge thereof lying on a first engagement circumference having a smaller diameter than a second circumference on which a lower edge of said engaging surface portion (7) is arranged and wherein the tooth formation has a tip lying on a third circumference the diameter of which is smaller than the diameter of said second circumference. A chuck according to claims 1-6, wherein said supporting member (3) has on the side on which said jaws (4, 5 and 6) are supported an annular crown formation (3a) with an annular resting surface thereon for allowing the bottom (2a) of the body portion to be held by the chuck device to rest thereon and wherein said crown formation (3a) has a depression (3c) for receiving therein said tooth formation (8). A chuck device according to claims 1-7, wherein said pivot axis (10) is materialized by a pivot (10) supported on studs (11a, 11b) and is upwardly offset with respect to said crown formation (3a) to allow radial forces directed below said pivot axis (10) to press said body portion against said crown formation (3a). A chuck device according to claims 1 to 8, wherein said jaw members have locking means (14) for selectively locking said jaw members in the closing position thereof and thereby press said jaw members against said supporting member (3). A chuck device according to claims 1 to 9, wherein said locking means are screws (14) axially slidable within limits within hole defining means (15) provided in said jaw members and cooperating with femal screw thread means (16) provided in said supporting member (3), spring means (15a) being provided for urging said screw upwards to allow the upper ends of said screws to pop out of said hole defining means when disengaged from said female screw thread means (16).

Inventors: CALARI, ALESSANDRO
Applicants: DIDECO S.P.A.
Application year: 1988
Main classification: B04B5
IPC codes: B25B5, B25B11, B04B7, B04B9