EP0412004A2 - Rotary comminutor and container for manipulating objects containing toxic or radioactive elements - Google Patents

Abstract

The comminutor according to the invention enables objects to be reduced to small dimensions while avoiding problems of rotor blockage. It comprises chiefly a casing (2) to which are fixed dead knives (20). A rotor (10) is mounted rotatably inside the casing (2) and is formed from discs carrying equal numbers of knives (12) set off at angular intervals. The knives (12) and dead knives (20) are positioned on the axis of rotation (8) and the casing (2) respectively, in such a way that a gap is left between all the lateral faces of the knives (12) and of the dead knives (20) to prevent any contact between these parts. The motor is reversible to allow the rotor (10) to be released in the event of jamming and to allow operation in both directions of rotation of the rotor (10). Application to a container for the comminutory handling of radioactively contaminated objects or objects containing toxic elements. <IMAGE>

Description

FIELD OF THE INVENTION

The invention relates to the manipulation of objects, such as small tubes containing toxic or radioactive elements or products, as is the case in research or the nuclear industry, as in nuclear medicine or medical laboratories. The invention relates more precisely to the shredders making it possible to considerably reduce the volume of these objects, which must be stored. Such a crusher is therefore often associated with enclosures of the glove box type.

PRIOR ART

In the context of the use of toxic or radioactive products, we most often have to eliminate the products used and the material they have contaminated. Then there is often talk of storing these products or objects in storage containers. In particular, in the medical field, operators are more and more often called upon to handle vials or syringes that have been contaminated with toxic products. Safety standards impose the storage for a determined period of this waste consisting of contaminated products or objects.

Just like storing simple bottles or empty packaging, storing small vials of glass or syringes is very bulky, compared to the weight of material stored. There is therefore a need to reduce the final volume of this waste to make the storage of this waste profitable.

It is known to use rotary grinders to transform small objects, such as vials or syringes, into small breakages. They generally consist of a rotor mounted to rotate and the radial knives of which pass between the counter-knives fixed in the casing of the mill. By a cutting phenomenon similar to that of a pair of scissors, the waste is thus destroyed. On the other hand, when an object is subjected to the rotation of the rotor under the simultaneous action of several knives, its meeting with the counter-knives can cause, depending on its position, a brutal bracing or an excessively brutal accumulation of resistance to the rotation of the rotor, causing it to stop. This blocking phenomenon can be favored by the presence of the mixture of glass constituting the bottles and of rubber constituting the caps of the bottles, the amalgam being able to constitute a material favorable to the blocking of the rotor.

Once the rotor is blocked, a waste of time inherent in unlocking is detrimental to the operation of such a crusher, without taking into account the fact that this unlocking must be obtained manually.

The object of the invention is to remedy these drawbacks by proposing a grinder capable of minimizing the number of blockages, and of being self-unlocking.

SUMMARY OF THE INVENTION

To this end, the first main object of the invention is a rotary mill comprising a casing inside which is placed a grid carrying counter knives, a rotor mounted rotating in the casing around an axis of rotation and comprising several knives, a motor for rotating the rotor.

According to the invention, the rotor consists of discs each carrying knives of a determined thickness and being spaced by a determined distance, the counter knives being inserted between the knives during the rotations of the rotor, the counter knives being spaced apart by a distance greater than the thickness of the knives, but being of a thickness less than the distance separating the knives, so that the rotor can rotate in the grid, without the knives touching the counter knives. The fact that the knives and the counter knives are separated promotes grinding and prohibits most blockages. It also promotes the rotation in the opposite direction of the rotor, in order to obtain an unlocking of the mill.

In the preferred embodiment, the rotor discs have the same number of knives and are fixed to each other coaxially with respect to the axis of the rotor offset angularly, so that several knives are not angularly positioned in the same way . Preferably, the discs are fixed so that the knives form oblique rows relative to the axis of rotation of the rotor.

According to one aspect of the invention, the motor is reversible and the shape of each knife, in the plane of the disc, is symmetrical with respect to a plane passing through the axis of rotation, so as to cause in both directions of rotation the same phenomenon of grinding of the rotor, the counter knives being divided into two separate groups, the attack phases of the counter knives being the same in the two groups.

Blockage is also avoided thanks to the fact that the attack phase of the counter knives is placed in the horizontal plane containing the axis of rotation of the rotor, and that the shape of each knife in the plane of its disc is pyramidal, of so that the passage of the leading face of each knife in the plane of the leading face of each counter knife is done gradually, starting at the point located near the base of the knife and ending at its end.

According to a preferred embodiment of the knives, these have a slightly thinner thickness as one moves away from the center of the disc, the thickness at the end of the blade being approximately equal to 3 mm.

According to one aspect of the invention, a worm gear reducer is used so that the rotor rotates at a rotational speed of the order of a few revolutions per minute.

In its preferred embodiment, the crusher has an upper opening in the housing, above the grid, for introducing the objects to be ground and a lower opening in the housing, below the grid, for discharging the crushed waste.

The crusher is advantageously completed by a loading system placed above the upper opening and comprising:
- a bottomless drawer defining an internal volume whose manual access is limited by a ledge; and
- a drawer housing inside which the drawer slides, completely surrounding this drawer and having a loading hole placed below the drawer when the latter is in the closed position to prevent the operator's hand from accessing the rotor and only allow objects to be loaded into the crusher when the drawer is in the closed position.

Means for driving objects, placed at the end of each knife, can facilitate or accelerate the grinding.

A second main object of the invention is an enclosure for handling products or objects containing toxic or radioactive elements, the enclosure being of the glove box type, the handling of the objects being done by an operator placed outside. of the enclosure and by means of gloves and circles of gloves, and having a hole for evacuating objects by gravity in a receptacle.

According to the invention, a grinder, as summarized in the preceding paragraphs, is fixed opposite the discharge hole to grind the products handled in the enclosure and transform them into waste in the form of pieces of small dimensions, to reduce the volume required for the storage of these objects.

LIST OF FIGURES

• - figure 1, une vue de dessus du broyeur selon l'invention ;
• - figure 2, une vue latérale en coupe du broyeur selon l'invention ;
• - figure 3, une vue éclatée du rotor du broyeur selon l'invention ;
• - figure 4, une demi vue de dessus en coupe du broyeur selon l'invention ;
• - figure 5, le broyeur selon l'invention, équipé d'un premier système de tri des déchets broyés ;
• - figure 6, le broyeur selon l'invention, équipé d'un second système de tri des déchets broyés ;
• - figure 7, une enceinte de manipulation d'objets toxiques, équipée d'un broyeur selon l'invention.

The invention and all of its technical characteristics will be better understood on reading the description which follows, appended to the various figures representing respectively:

• - Figure 1, a top view of the mill according to the invention;
• - Figure 2, a side sectional view of the mill according to the invention;
• - Figure 3, an exploded view of the rotor of the mill according to the invention;
• - Figure 4, a half top view in section of the mill according to the invention;
• - Figure 5, the crusher according to the invention, equipped with a first sorting system of crushed waste;
• - Figure 6, the crusher according to the invention, equipped with a second sorting system of crushed waste;
• - Figure 7, an enclosure for handling toxic objects, equipped with a grinder according to the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

FIG. 1 makes it possible to distinguish the main parts of the mill according to the invention.

It further comprises a casing 2 inside which is placed a rotor 10 carrying several discs 12, the periphery of which is cut to form several knives 14. The rotor 10 is mounted rotating around an axis 8 and is driven in rotation by means of an electric motor 4, preferably by means of a speed reducer 6. The one shown in FIG. 1 is of the worm and worm type, this being only one example of production. In general, the speed of rotation of the rotor 10 is a few revolutions per minute.

FIG. 2 specifies the various technical characteristics inherent in the mill according to the invention.

There is the housing 2 inside which is mounted rotating the rotor 10. On each side of the housing 2, is fixed a series of parts 20, called "knives" throughout the description and claims. As indicated by this designation, these counter knives 20 cooperate with the knives 10 to obtain the grinding of the objects introduced into the casing 2.

Also shown in FIG. 2 is a rotation shaft 16 on which the rotor 10 made up of several discs 14 is fixedly fixed in rotation. This rotational attachment can be effected by means of a key 18.

The exact mounting and positioning of the counter knives 20 relative to the knives 12 will be explained below, with reference to FIG. 4.

In this figure 2, there is also below the casing 2, a hopper 22 intended to collect the crushed waste. It is commonly fixed on the casing 2. The top of its pyramid ends in a neck 24 placed at the bottom of the assembly. At this neck is fixed a storage or transport receptacle 26, such as a container.

It is thus understood that the objects to be shredded are introduced through the upper part of the casing 2, preferably on an inclined plane 28 placed inside the casing 2 to bring the objects against the knives 12, considering the direction of rotation in accordance with that of the hands of a watch. The objects are then subjected to a grinding effect, since they are trapped between the knives 12, the counter knives 20 and the lateral internal wall 30 of the casing 2. The waste thus obtained is collected in the hopper 22 and accumulated in receptacle 26.

Figure 3 details the mounting and positioning of the discs 14 on the shaft 16 of the rotor 10. Preferably, each disc 14 has the same number N of knives 12. In order to ensure continuous grinding and to avoid phenomenons too brutal bracing, jamming or accumulation of force on the rotor of the crusher, each disc 14 is positioned angularly offset with respect to the other discs 14. For example, considering the disc 14A in the upper part of the figure, it has been positioned so that one of these knives 12A is vertical. The other knives of this disc 14A are therefore positioned as a function thereof.

Considering the disc 14B in the middle of the figure, we see that the upper knife 12B is angularly positioned, slightly offset from the position of the upper knife 12A of the disc 14A (angle W). The other knives of this disc 14B are therefore positioned relative to this knife 12B and are themselves offset relative to the other knives of the first disc 14A.

In the same way, the third disc 14C has its upper knife 12C again angularly offset relative to the upper knife 12B of the disc 14B (angle 2W). This offset is then equal to twice the offset between the knives 12A and 12B. In general, the offset of the discs 14 relative to one another must be chosen so that two knives of two different discs are never in the same angular position. In other words, when the disc 14A rotates with the rotor, the front end 13A of the knife 12A is the only knife end to pass opposite the vertical line, marked 15 in FIG. 3. Therefore, in Returning to FIG. 2, it is understood that when a long object, namely a syringe, is wedged between the lateral internal wall 30 of the casing 2, the counter knives 20 and the rotor 10, the latter exerts its force at a determined instant with a single knife 12. The pressure applied to the object to be ground is therefore maximum.

As shown in FIG. 3, the positioning along the axis 8 of the rotor 10 is done by means of axial spacers 32.

The preferred shape of the knives 12 is that shown in the figures, that is to say an elongated shape, slightly pyramidal. More precisely, in the plane of the disc, each knife has a radially elongated trapezoidal shape. In general, to obtain a good grinding result, according to the invention, the shape of each knife must be such that all the points of the attack face 11 of a knife do not correspond at the same time with all of them. the points of the attack face 21 of a counter knife 20.

For this purpose, as shown in FIG. 2, it is advantageous to position the leading face 21 of the counter knives 20, at the level of the axis 8 of rotation of the rotor 10. It is indeed in this zone that the blades 12 of the rotor 10 have the most force. It is therefore important that the leading face 11 of the knives 12 be in a plane which does not pass through the axis of rotation 8, so as to be inclined relative to the leading face 21 of the counter knives 20. When these two faces meet, the crossing of a knife 12 relative to a counter knife 20 is done first by a point 23 of the base of a knife 12, then the meeting point goes up the knife to arrive at the end 25 of the knife 12.

FIG. 4 specifies even better the respective shapes and positions of the knives 12 and counter knives 20. In this top view, the discs 14 are separated by their axial spacers 32. They each penetrate between two counter knives 20. The mounting of the latter in the housing 2 is also done by means of spacers 34 placed between each of the counter knives 20. The fixing of the counter knives 20 is symbolized by tightening, by means of a screw-nut system.

The principle governing the shape and mounting of the knives 12 and the counter knives 20 is that there is a space between the side walls 38 of the knives 12 of the discs 14 and the side wall 39 of the counter knives 20, so as to avoid a phenomenon of contact shearing, similar to that implemented by a pair of scissors. In other words, the distance D₂₀, separating two counter knives 20, is greater than the thickness E₁₄ separating two discs 14 and the thickness E₂₀ of the counter knives 20 is less than the distance D₁₄ separating two discs 14.

To improve the efficiency and the lifetime of the mill, according to the invention, the rotor 10, in particular, is made of hardened steel.

On the other hand, the crushing phenomenon can be promoted by the use of drive means, such as small hooks or brushes 36 placed at the end 25 of each knife 12 (see FIG. 2). Indeed, if the objects tend to slip away from the rotational effect of the rotor and remain tangent at the end of the knives 12, hooks or brushes 36 favor the entrainment of these objects.

The mill according to the invention is equipped with a reversible motor. Indeed, in the event that a blocking or "jamming" phenomenon occurs in the crusher, a rotor 10 rotation control in the opposite direction of usual operation makes it possible to release the knives 12 wedged in the counter knives 20.

It is also possible to provide a manual unlocking system by means of a crank which can engage on the shaft 16 of the rotor 10.

The fact that the motor is reversible also allows the two lateral groups of counter-knives to be used alternately. In fact, if the attack faces 21 exist on the two groups, the symmetry of the knives 12 and the two directions of motor rotation allow grinding on both sides.

FIG. 5 shows a first accessory which can be used with the crusher according to the invention, for grinding objects containing both solid materials and liquid materials. It is a sorting device placed in place of the hopper 22 of FIG. 2 to receive the crushed waste. This sorting device comprises a main grid 42 inclined inside the sorting hopper 44. The crushed waste 46 falls on this grid 42, through which the liquid 48 can easily flow. This is collected in a first container 50 connected to a first neck 52 of the sorting hopper 44. The solid waste is removed at the bottom of the grid 42 in a second container 54 connected to the sorting device 40 by a second neck 56 .

This sorting device can be particularly effective when the crushed objects are small containers, such as vials or syringes containing liquid.

With reference to FIG. 6, a second sorting device can be used with the crusher, when the latter is used to grind different materials. This second device consists mainly of two receiving channels 41 and 43, placed below the mill, each on one side, vertical to the end of the knives 12, when they come out against the knives 20. A spout divider 45 joins the central walls 47 and 49 of the two channels and goes up between the knives 12, in the same way as the counter-knives 20, vertical to the axis of rotation 8.

It is thus possible to grind objects made of a first material, for example glass, by rotating the rotor in a first direction of rotation, the waste being recovered by a first channel. Similarly, by reversing the direction of rotation of the rotor, it is possible to grind objects made of a second material, for example a plastic material, and recover the waste by the second channel, the dividing spout 45 preventing the passage of waste. towards the opposite side. The exploitation of waste thus sorted is facilitated.

Considering FIG. 7, the crusher according to the invention is advantageously used on an enclosure for handling objects containing toxic or radioactive elements. Indeed, in nuclear medicine and in medical laboratories, we have to handle many vials or syringes that have contained or still contain radioactive products. The standards of ANDRA (National Agency for the Management of Radioactive Waste) impose complete storage for determined periods of contaminated products or objects. This storage requires large volumes in which these waste is stored. It therefore appears necessary, or at least very advantageous, to minimize the volume of this waste to be stored. Grinding contaminated objects is therefore a necessary measure. The manipulation enclosure of FIG. 7 is of the glove box type. That is to say that the upper part 52 of the enclosure is sealed. The manipulation of the objects inside it is done by operators acting inside by means of gloves which are themselves tightly connected to the wall of the enclosure by glove holes 54. They control their handling through a window 56 placed on the upper part 52 of the enclosure.

This can contain various accessories, such as a cupboard 58 or a device 60 for feeding the objects to be shredded. In fact, the operator can grasp objects 64 in inlet holes 62, placed above a supply device 60. Once an object 64 has been grasped, the hole 62 is filled in with a sliding plug and the The object is placed in a loading device of the crusher.

The latter, marked 70, is fixed below the upper handling part 52. We distinguish its motor 72, the receptacle 74 of crushed waste and various potentiometer control buttons 76 placed on the right side of the enclosure.

The handling of a shredder implies the existence of a potential danger. Consequently, a safety device is provided at the level of the loading of the objects 64 into the crusher 70.

According to the invention, this loading system mainly comprises a bottomless drawer 78, partially covered with a flange 80. It is surrounded by a housing 82 inside which it slides.

The use of such a loading system is as follows.

The operator opens the drawer 78, loads the object or objects 64 to be ground there and closes the drawer 78 in its housing 82. The drawer 78 being bottomless, the objects fall into the crusher 70 thanks to the presence of a hole 83 practiced in the upper part of the mill, and offset from the place where the operator introduces the objects 64. In this way, access to the rotor of the mill by the operator's hand is defended by a labyrinth consisting of the drawer 78 fitted with its rim 80 and the hole 83 of the grinder.

Provision can be made for the automatic starting of the crusher 70 when the drawer 78 has just been closed. A control device can then be constituted by a switch 84 placed at the bottom of the drawer 82 housing, actuated when the drawer 78 comes into its closed position against this switch 84. The latter can start on the one hand the rotation of the rotor of the mill 70 and on the other hand, a time delay 86 defining a determined time of rotation of the rotor, so as not to operate the mill 70 excessively.

Claims (13)

1. Rotary mill comprising:
- a casing (2);
- a rotor (10) mounted rotating around an axis of rotation (8) in the casing (2) and comprising several knives (12);
- a grid fixed inside the casing (2) and made up of counter knives (20); and
- a motor (4, 72) for rotating the rotor (10),
characterized in that the rotor (10) consists of several discs (14) of thickness (E₁₄) carrying each of the knives (12), the discs being spaced apart by a determined distance (D₁₄), the counter-knives ( 20) fitting between the knives (12) without touching them, being spaced apart by a distance (D₂₀) greater than the thickness (E₁₄) of the knives (12) of the discs (14) but being of a thickness (E₂₀ ) less than the distance (D₁₄) separating the discs (14), so that the rotor (10) can rotate in the grid without the knives (12) touching the counter knives (20). 2. Crusher according to claim 1, characterized in that the discs (14) have the same number N of knives (12) and are fixed to each other coaxially with respect to the axis (8) of the rotor (10) offset angularly, so that several knives (12) are not angularly positioned in the same way. 3. Crusher according to claim 2, characterized in that the discs (14) are fixed so that the knives (12) form oblique rows relative to the axis of rotation (8) of the rotor (10). 4. Crusher according to any one of claims 1 to 3, characterized in that, the motor being reversible, the shape of each knife (12) in the plane of the disc (14) which carries it, is symmetrical with respect to a plane passing through the axis of rotation (8), so that there is in the two directions of rotation of the rotor (10) the same phenomenon of grinding, the counter knives (20) being divided into two groups separated from the sides, the leading faces (21) of the counter knives (20) being the same in the two groups of counter knives (20). 5. Crusher according to any one of claims 1 to 4, characterized in that:
- The leading face (21) of the counter knives (20) is placed in the horizontal plane containing the axis of rotation (8) of the rotor (10); and
- The shape of each knife (12) in the plane of its disc (14) is pyramidal, so that the passage of the leading face (11) of each knife (12) in the plane of the leading face (21) of each counter knife (20) is done gradually, starting with the point (23) located near the base of the knife (12) to end at its end (25). 6. Crusher according to any one of the preceding claims, characterized in that the thickness of each knife (12) is slightly thinned as one moves away from the center of the disc (14), the thickness of the end (25) of each knife (12) being of the order of 3 mm. 7. Crusher according to any one of the preceding claims, characterized in that it comprises a speed reducer of the worm-type (6) so that the rotor (12) rotates at a speed of the order of a few turns per minute. 8. Crusher according to any one of the preceding claims, characterized in that it comprises an upper opening in the casing (2) above the grid consisting of the counter knives (20) for introducing the objects to be ground and an opening lower in the casing (2) below the grid made up of the counter knives (20) to evacuate the crushed waste. 9. Crusher according to claim 8, characterized in that it comprises a loading system placed above the upper opening of the casing (2), and consisting of:
- A bottomless drawer (78) defining an internal volume whose manual access is limited by a flange (80); and
- A housing (82) of the drawer (78) completely surrounding this drawer (78) and inside which the drawer (78) slides and having a loading hole (83) located below the drawer (78) when this- it is in the closed position, so as to prevent access to the rotor (10) by an operator's hand and load the objects (64) into the crusher, when the drawer (78) is in the closed position. 10. Crusher according to any one of the preceding claims, characterized in that it comprises at the end (25) of each knife (12) means for driving objects to be ground. 11. Crusher according to claim 4, characterized in that it comprises a waste sorting device placed below the rotor (10) and consisting of two lateral receiving channels (41, 43) separated by a dividing spout (45) for receiving the waste respectively from the two sides of the rotor (10). 12. Enclosure for handling products or objects containing toxic or radioactive elements (64), of the glove box type, the handling of the objects (64) being carried out by an operator placed outside the enclosure and by the intermediate of gloves and glove rings (54) and having a hole for evacuating objects (64) by gravity in a receptacle (70), characterized in that it comprises a grinder of the type defined by any one of Claims 1 to 11, fixed opposite the discharge hole for grinding the products (64) handled in the enclosure and transforming them into waste in the form of small pieces to reduce the volume necessary for their storage. 13. An enclosure according to claims 9 and 12, characterized in that the crusher comprises a time delay (86) controlled by a switch (84) placed at the bottom of the housing (84) of the loading system and controlled by the drawer (78) when the latter arrives in the closed position, so as to control the rotation of the rotor (10) for a determined period.

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