EP0407678B1 - Feeder for a crusher - Google Patents

Description

The present invention relates to a supply device for apparatuses in substance in viscous state containing or not crushable aggregates, in particular for roller mills, comprising a displaceable circular tank containing said substance, a circular push-plate displaceable by the top along and inside the tank by means of an actuating device to ensure the flow of the substance from below when the tank is placed above the grinder, the pusher plate being provided with '' a seal that can be applied against the wall of the tank (see document US-A-3 643 876)
Such devices are in common use, for example in the printing ink industry, in the food industry or in the cosmetics industry.

The feeding consists in pouring the substance intended to be worked above the grinder at the desired location, that is to say in the "grip" zone of the first two cylinders.

This operation poses the fundamental problem of its integrated automation, to which the state of the art has not, to date, provided a satisfactory solution. In fact, this problem contains two underlying problems that are closely related to each other. These should therefore be resolved so that the response of one combines with the response of the other.

The first problem comes from the extrusion of the substance out of the tank. In the vast majority of cases, the substances to be worked do not flow by gravity or at least not easily. However, in feeders for grinders, the flow of substance is made, the tank being placed above the grinder, through an opening in the bottom of the tank, the passage being able to be released by means of a valve or slide plate. But this release of passage will therefore not be followed by flow: The substance contained in the tank remains frozen. The flow can take place only under the exercise of an external force which "shears" the substance. Also, to cause the extrusion of the substance, the pusher plate mentioned in the introduction is actuated in order to rest on the substance and by the same exert on it a thrust. A seal is placed on the peripheral surface of the tray. The seal between the plate and the tank is obtained using a conventional or inflatable seal. However, two difficulties remain unsolved: on the one hand, that of the opportune moment when the inflation of the seal must take place (when such a type of seal is used), taking into account the position of the plate relative to the upper levels of the substance in the tank. Indeed, the substance having a high viscosity, the differences in level must first be corrected so that there is practically no more air between the level and the active face of the plate, a prerequisite for the flow of the substance takes place under good conditions. On the other hand, when the seal has a defect, whatever the type of seal, for example in case of puncture of the inflatable seal if this type of seal is used, the actuating device continues to exert its thrust on the plate , which will cause the substance to overflow. Such overflows lead to immobilization of the shredder and cleaning operations which, in the field of use of printing inks, can exceed 2 hours; they should therefore be avoided at all costs.

To overcome these drawbacks, the pusher plate comprises means coupling the triggering of the seal as soon as the pusher plate levels the surface of the substance contained in the tank.

The second problem is an extension of the first and consists of combining the operation of the tray with that of a device for taking care of the tank, in other words, creating an integrated and compact supply device, in the goal of optimal use of it.

According to the invention, this second problem is solved by the fact that the pusher plate and the actuating device thereof for ensuring the flow of the substance are mounted on the device for taking charge of the tank. Complementing this characteristic, this support device comprises means for bringing the tank from a starting position, the tank being placed on the ground or close to it, to a position above the grinder, and Conversely. In addition, means provide the command and control of the flow of the substance.

Thus, the means proposed according to the invention for solving the two problems set out above lead to a semi-automatic or fully automatic feeding device, the operation of which satisfies optimally the criteria of speed, safety, and quality d 'execution of the extrusion operations of the substance.

la fig. 1

représente une vue de dessus du plateau-poussoir,

la fig. 2

est une coupe selon la ligne II-II de la fig. 1,

la fig. 3

est une vue de détail partielle du plateau-poussoir,

la fig. 4

est une vue de face du dispositif de prise en charge de la cuve,

la fig. 5

est une vue de côté du dispositif de prise en charge de la cuve, et

la fig. 6

est une coupe selon la ligne VI-VI de la fig. 5.

The invention will be described, by way of example, in support of the appended drawing in which:

fig. 1

represents a top view of the push plate,

fig. 2

is a section along line II-II of FIG. 1,

fig. 3

is a partial detail view of the push plate,

fig. 4

is a front view of the device for taking charge of the tank,

fig. 5

is a side view of the tank handling device, and

fig. 6

is a section along line VI-VI of FIG. 5.

For the description of the pusher plate 1, reference will be made simultaneously to FIGS. 1 and 2. This plate consists of a circular plate 3 in the center of which, on one of its two faces, is welded a hub 4. This hub is thus oriented on the side which will be called the outer side. On the periphery of the plate 3 is welded a ring 8, so that the latter is oriented entirely on the outer side, the inner edge 27 of the ring being located in the same plane as the inner face 29 of said plate. Ribs 6, six in number in the example described, give the plate the necessary rigidity. A cover 7 covers the outside of the tray. This cover is fixed on the face 28 of the ring 8 by means of screws not shown and forms, with the outer face 30 of the plate 3 and the inner annular face 33 of the ring 8 a closed space 31. Instead of '' consisting of 3,4,6 welded elements, the pusher plate can also be a foundry piece. The ring 8 has on its outer peripheral face 32 a groove 9 whose profile, in the variant shown is U-shaped, and in which is housed a seal 11, for example made of neoprene, of approximately section parallelepiped. The residual space formed by the groove 4 and the seal 11 constitutes an air chamber 12 which communicates with the space 31, that is to say with a source of compressed air not shown, via a pneumatic distributor 15, by an opening 34 and an air chamber connector 13. In place of a full section joint, it is possible to accommodate in the groove 9, the profile of which may differ from that mentioned above, an inflatable hollow joint which is then itself provided with a valve communicating with the outside, that is to say with the source of compressed air. The source of compressed air is itself connected to the connector 13 by means of a pipe 14, of a wall passage 17, the pipe being fixed by means of nuts 16, of the pneumatic distributor 15, which is connected to fitting 13 by pipe 18.

On the inner face 29 of the plate 3 of the pusher plate 1 is arranged a ring 10 which can have a central groove 35. A sheet 26, preferably made of plastic, is stretched over the plate, at a certain distance D from the face 29, by virtue of said ring 10, and at a distance d from contactors 19 (FIG. 3) mounted on the same side in the plate 3. The groove 35 has the function of creating a pre-tension on the sheet 26 and simultaneously release the sheet 26 from the contactors 19. In this way, the surface irregularities of the substance 24 contained in the tank 20 are corrected, the pusher plate 1 not fulfilling its sealing function by means of its seal 11, as well as as will be seen later, only from the moment it is close to the substance 24. This plastic sheet fulfills the function of probe, it being understood that other means can be chosen to perform this function. In the variant described, these contactors, of known type, are three in number. Their location is each time at vertex of an equilateral triangle inscribed in a circle of radius r, of value approximately equal to half of the radius of the push plate or slightly greater than this half. Each contactor 19 corresponds to a control mechanism 41 arranged in the space 31. As will be seen below, the control mechanisms trigger, under certain conditions, the pressure in the chamber 12, when an impulse is delivered to them by the contactors.

In fig. 2, the tank 20 containing the substance 24, the valve 22 being in the closed position, is shown a thin dashed line. The pusher plate is located at a certain distance above the substance 24. The bottom of the tank has, in its central zone, an opening 21. The valve 22, operable manually or automatically by means of an operating screw 23, makes it possible to completely close the opening 21 or to leave a more or less large passage between the two extreme positions (total opening / closing), to allow a more or less significant flow of the substance 24.

The push plate 1 is screwed by its hub 4 to a shaft 5 extending the actuating device 50 mounted on the support device 2 of the tank (Fig. 4), which device will be described later. The push plate, also linked in rotation, is thus integral with these two devices. Once the tank 20 is wedged on the support device, the latter being in the starting position, the axis 36 of the plate and the axis 37 of the tank have the same support. The plate 1 can then be put into action. This actuation follows the following process: during a first phase, the plate descends at a speed of the order of 6-10 cm / s and enters the tank, either under servo, for example pneumatic or hydraulic, of the device 50, or under the action of its own weight, until the pre-stretched sheet 26 will come into contact with the substance. The pusher plate 1, the seal 11 of which does not yet fulfill its sealing function and which is therefore only very slightly or not at all in contact with the wall of the tank, slides along the latter, only the sheet 26 being interposed. The seal between the push plate and the tank occurs at the end of the second phase. In fact, when the descent of the plate continues, the highest vertex 38 of the substance 24 will come into contact with the sheet 26, so that the latter will be subjected to an elastic deformation and approach the face 29 of plate 3 (reference 40 - Fig. 3), until finally coming into contact with one of the contactors 19. Very sensitive contactors will be chosen, so that at the first request from one of them, an impulse is supplied to its corresponding mechanism. When at least one of the three mechanisms has recorded a signal, the air chamber 12 is pressurized - by about 4 bars in the variant executed - via the pneumatic distributor 15. The air pressure will cause the seal to be pressed 11 against the inner wall of the tank. Sealing is then ensured. For the reason which will be explained, the triggering of the pressure is preferably controlled when at least two of the three contactors have been pressed. In the example shown in Figure 2, when the sheet 26 comes into contact with the top 38, the substance 24 will be spread, the plate 1 continuing its descent. At a certain moment, which will correspond to a position of the plateau in the vicinity of a second vertex 39, which meanwhile, following the planarization undertaken, will probably no longer have quite the same configuration, nor the same coordinates, the sheet will come into contact with the second or even simultaneously with the third contactor 19. The second or / and third signal recorded, the pressurization of the chamber 12 is immediately ordered. Also, when the seal 11 is pressed against the wall of the tank 20, the upper level of the substance will be more or less uniform, that is to say that the differences in levels will have been corrected, and the volume of air any remaining residue will be minimal and will no longer have a harmful effect. It is understood that the sheet 26 is previously stretched, since this tension makes it possible to remove any premature and undesirable impulse. This second phase is followed by a third, namely that of the flow of the substance 24 through the opening 21, the tank assembly, pusher plate and actuation device thereof being carried above the grinder (sealing being established) by means of the device 2 for taking care of the tank which will now be described. A device for controlling the seal which makes it possible to avoid any escape of the substance 24 between the tank and the plate, as well as means for controlling and controlling the extrusion, will be further described in this context.

Figs. 4 and 5 respectively represent a front view of this device for taking charge of the tank and a side view. The device is presented as a rigid frame, made up of mechanically welded sections, comprising a double bracket, that is to say a left bracket 52 and a right bracket 53, both arranged symmetrically on either side of the shredder 50 relative to a plane of symmetry 59 (the latter merging with the plane of symmetry of the shredder 50) and a stirrup 58. Each bracket is formed by a vertical support arm 54 and a support arm 55 , the latter being horizontal or approximately horizontal, when the support device is in the starting position, as shown in the figures; (thereafter the identical constituent elements or corresponding by left / right symmetry bear the same tag or will be tagged only once as the description will only refer to one item each time). The support arm consists of two uprights 61, 62 of the same height in a U-shaped section, the wings of which are placed opposite one another (Fig. 6). The lower end of these uprights is welded to a seat plate 60, itself anchored in the ground by means of anchoring screws 64. Reinforcement triangles 63 give these uprights 61,62 the desired rigidity. In general, reinforcements of this type, which are provided at the appropriate locations in accordance with the construction rules known to those skilled in the art, are partly represented in the figures, but are not identified and will not be mentioned by the following.

A bearing 68 of axis 56 is mounted on a support 67 oriented towards the grinder and fixed perpendicularly to the upper end of the upright 54. The two support arms are pivotable at their rear end around the axis 56 and can jointly take any position between the starting position and an elevated position (shown in thin phantom in Fig. 5). At the front ends of the support arms are mounted yokes of common axis 57, around which the stirrup 58 is pivotable. The two support arms are moreover connected to each other by a reinforcing bar 69. In the designed variant the support arm has a determined length, adapted to a single type of grinder for the supply of which the device is provided. In other variants, not shown, provision is made for adapting the arm to different types of grinders. The arm is then composed of at least two 1/2 parts, a 1/2 part of the rear arm and a 1/2 part of the front arm, approximately of equal length, linked together by a flange. A spacer can then be interposed between the front half-arm and the rear half-arm. According to a variant, the adaptation of the support arm the type of grinder can even be obtained automatically by means of a jack, the fixed barrel of the jack being secured to the front or rear arm, the telescopic rod then being secured to the rear or front arm, respectively. These variants make it possible to manufacture standard support devices. The pivotable stirrup 58 has a cross-member 70, for example in a section with a parallelepiped or square section, each end of which is provided with a shaft housed in the corresponding yoke of axis 57. Two left and right stirrup uprights 71 are welded on the lower field of the cross-member 70, so that the tank 20, drawn in phantom in the figures, can take place on support guides 74 welded to the lower part of each upright 71. When the tank is placed in placed on the support guides 74, the tank 20, supported by said guides, is blocked by the elements bearing the mark 75, this mark designating both a cleat welded to the tank and coming to be housed in a stop part in U shape turned 90 ° forward and a locking pin. Under each stirrup post 71, there is a positioning lug 72 which can be received in a positioning hole 73 when the support device is in the lowest position. The actuating device of the push-plate 1 is mounted on the cross-member 70, the axis of this device, vertical, being located in the plane of symmetry 59. Pivoting around the axis 57, the caliper assembly 58, device actuator 51 provided with the plate 1 and tank 20, always remains vertical.

It was indicated above that the support arms 55 are pivotable about the axis 56. The extreme positions - low and high - are shown in FIG. 5. These positions, and those in between, can be taken by the action of a jack 66 arranged in the space 65 formed by the uprights 61 and 62 (FIG. 6) and the telescopic rod of which is in connection with the support arm 55, as shown in FIG. 5, the connecting elements, of known type, not being identified. Safety stop switches 76 and 77 avoid any risk that the support arms 55 exceed the extreme positions.

The tank handling device operates as follows: the device being in the low position or starting position, as shown in figs. 4 and 5, the tank 20 is brought to the support guides 74, and the assembly 75 (cleat / housing-stop / pin) is locked. The support guides 74 and the assembly 75 are arranged so that at this moment, the axis of the tank corresponds to the axis of the actuating device 51, therefore also to that of the push-plate 1. This the latter then comes into action as described above, until the operations of leveling the substance 24 and placing the seal 11 against the wall of the tank 20 are completed. Then the jacks 66 tilt the arms 55 supporting the stirrup 58 provided with the tank 20 towards the raised position (thin mixed lines in FIG. 5). The valve 22 is open and the pusher plate 1 moves along the tank, under the action of the device 51. This valve can only open if the position detector 77 is activated. Subsequently, the grinder is supplied with substance 24, the feed rate being able to be adjusted and modified by acting on at least one quantity. Two will preferably be chosen, namely the pressure of the jack 51 on the pusher plate 1 and the section of the opening which can be modified by means of the valve 22. In addition, parameters specific to the settings of the grinder can be taken into account. (e.g. speed of rotation of cylinders, level of substance in the feed hopper), properties of the substance (e.g. viscosity), etc. According to a simplified version of the feeding device, the opening of the valve 22 of the tank 20 is made manually, once the support device is in the raised position and the contactor 77 is engaged, while the pressure exerted on the plate is preset according to the viscosity of the substance 24 to work. For viscosities of the order of 7 Pa.s - 10 Pa.s and above, the pressure chosen will be approximately 40 bars. According to a more sophisticated version, the feed device is provided with means, not shown, which make it possible to automatically command and control the entire extrusion operation:

A device for tracking the levels of substance in the tank and in the grinder, for example an ultrasonic transmitter, transmits information continuously or at regular intervals to a control block which will deliver the appropriate pulses after processing this information in particular , to a motor engaged with the maneuvering screw 23, in order to adjust the opening of the valve 22 or / and to the motor supplying the appropriate pressure on the push-plate 1. It is understood that the exploitation of the information consists in calculating the opening that the valve 22 must allow to remain and the thrust that the jack 51 must exert, taking into account the levels recorded by the adjustment device and, if necessary, the other parameters, some examples of which are cited above. The automatic regulation of the different quantities, it being understood that the automation can be partial, that is to say limited to one or other of the quantities, optimizes the efficiency of the supply operation and will ensure operation shredder in the best conditions; moreover, this will prevent it from turning "dry".

But the action on the regulated quantities of the extrusion operation, with a view to an optimal yield from the treatment of substance 24 by the grinder 50, what that either the chosen operating mode, manual, partially or fully automatic, implies that upstream, the feed of the grinder in substance takes place effectively, that is to say that the pusher plate 1, by moving along and inside the tank, causes the substance 24 to be extruded through the opening given by the valve 22. This not only poses the problem of sealing between the pusher plate and the tank 20, but also that of his master's degree. The disadvantages caused by a leak have been explained in the introduction. Recall that the seal 11 is pressed against the wall of the tank 20 under the action of a pneumatic pressure of approximately 4 bars, after sufficient leveling of the upper zone of the substance, that is to say when at least two of the three contact detectors 19 have supplied their impulse to the corresponding control mechanisms. A leak is therefore caused by an air leak from the chamber 12 and will cause a pressure drop. According to the invention, means immediately cause the push-up plate 1 to rise, as soon as an air leak is detected. At the same time, in order to warn the operator of the anomaly, the detection of the leak triggers an audible signal. In the variant executed, the safety device chosen is an air flow detector: The air flow rate, when the desired pressure is reached, ie 4 bars in the example, must be zero. The existence of a leak, therefore the pressure drop, will be detected by the flow detector and will immediately cause the plate to rise and the sound signal. Any overflow of substance will therefore be avoided. The support device can be returned to the starting position and the causes of the leak can be investigated.

The feeding device according to the invention provides means providing an effective, rational solution and economical with the feeding problems of grinders, in particular in the printing ink industry, in the food industry, in the cosmetics industry, and, in general, in any industry processing substances with similar viscosity.

Claims (28)

1. Device for the supply of apparatus with a viscous substance containing or not containing grindable aggregates, more particularly for roller mills, comprising a circular, displaceable vat containing said substance, a circular thrust plate which is displaceable inside and along said vat from above by means of an actuating device in order to ensure the outflow of said substance at the bottom through an opening and a register when said vat is positioned above said mill, said thrust plate being provided with a sealing joint which is capable of being applied against the wall of said vat, characterised in that said thrust plate (1) comprises means for releasing said sealing action as soon as said thrust plate levels the surface of the substance (24) contained in said vat (20).
2. Device according to claim 1, characterised in that said means consist of contact detectors (19).
3. Device according to claim 2, characterised in that a control mechanism is associated to each detector, which is connected to a compressed air releasing device.
4. Device according to claim 3, characterised in that the number of contact detectors (19) is three.
5. Device according to claim 4, characterised in that the three detectors are disposed on the underside (29) of said thrust plate (1), their arrangement corresponding to the apex of an equilateral triangle comprised in a circle (radius r).
6. Device according to claim 5, characterised in that the radius (r) is equal to half of the external radius of said thrust plate (1) or slightly greater than said half.
7. Device according to one of claims 2 to 6, characterised in that said contact detectors (19) are subject to a sensor.
8. Device according to claim 7, characterised in that said sensor is a plastics sheet (26).
9. Device according to claim 7, characterised in that said plastics sheet (26) is stretched on a holding ring (10) which is mounted on the underside (29) of said thrust plate.
10. Device according to one of claims 1 to 9, characterised in that the seal between said thrust plate (1) and said vat (20) results from the cooperation of said joint (11) with an air chamber (12).
11. Device according to claim 10, characterised in that said joint (11) is in the form of a ring having a solid, parallelepipedic cross-section, preferably made of neoprene, in that it is inserted in an annular groove (9) of the plate (1), and in that said air chamber (12) is constituted by the remaining space formed by said groove (9) and said joint (11).
12. Device according to claim 11, characterized in that said air chamber (12) communicates with said compressed air releasing device through a pneumatic distributor (15), and in that the pressure of the air chamber is brought to a pressure (P) when at least one contact detector (19) is activated by said sensor (26), in such a manner that the joint (11) is pressed against the wall.
13. Device according to claim 12, characterized in that said air chamber is brought to the pressure (P) when two contact detectors (19) are activated.
14. Device according to claim 12 or 13, characterized in that the pressure (P) is about 4 bars.
15. Device according to one of claims 1 to 14, characterized in that a security device effects an elevation of said plate (1) when said device detects a fault.
16. Device according to claim 15, characterized in that said security device comprises a flow detector.
17. Device according to one of claims 1 to 16, characterised in that said thrust plate and the actuating device thereof for ensuring the outflow of the substance are mounted on a handling device for said vat (2).
18. Device according to claim 17, characterized in that said handling device of the vat further comprises means for bringing the vat from a starting position to a position above the mill and vice-versa.
19. Device according to claim 18, characterized in that said means for displacement of the vat are constituted by a double upright (52,53) and a stirrup (58) in which the vat (20) is accommodated.
20. Device according to claim 19, characterized in that each upright comprises a supporting arm (54) and a sustaining arm (55) which is hinged on an axle (56) at its rear end under the action of a jack (66), and in that said stirrup (58) is pivotably mounted on an axle (57) at the front ends of said sustaining arms (55).
21. Device according to claim 20, characterized in that two security contacts (76,77) limit the path of said sustaining arms (55).
22. Device according to claim 21, characterized in that said register (22) cannot be actuated until said contact (76) is switched on by said sustaining arm (55).
23. Device according to one of claims 17 to 22, characterized in that said actuating means of the thrust plate is a pressure cylinder acting upon said plate with a predetermined or variable pressure.
24. Device according to one of claims 1 to 23, characterized by means for ensuring the control and monitoring of the substance flow.
25. Device according to claim 24, characterized by means allowing to detect the substance levels in said vat and in said mill.
26. Device according to claim 25, characterized in that said detection is effected by ultrasonics.
27. Device according to one of claims 24 to 26, characterised in that the opening of said register (22) and/or the pressure exerted on said thrust plate (1) are regulated automatically in function of the substance levels in said vat and in said mill.
28. Apparatus, more particularly roller mill, characterised in that it is provided with a supply device according to one or several ones of claims 1 to 27.

Images