EP1577023A1 - Screening machine for drums having different diameters - Google Patents

Abstract

The sieving device has a frame unit which has at least one support means (3) for the mounting of a drum. The support means in a first position (5) are designed for the mounting of a drum of a first diameter (7) and in a second position for the mounting of a drum of a second diameter. The support means may be constructed for the mounting of at least three, four, or more drums with different diameters. The support means have at least two support elements (9) which are constructed preferably as rolling bodies (10).

Description

The invention relates to a screening machine with a rack device for rotatably holding a screen drum. The sieve drum can be designed as a drum screen. It is also possible that a separate screen is stretched on the drum.

In particular, the present invention relates to a mobile Trommel screen, which is designed to be movable, e.g. when Pendant.

Drum screening machines have become known in the art. By way of example, reference is made to that disclosed in DE 298 09 345 U1 Directed sieve machine.

Such drum screening machines are e.g. from contractors used to carry out the contract work. you will be For example, for sifting compost material or rubble used. For different requirements and for Different materials to sort can be different Siebfeinheiten be used. Many owners of drum machines have a plurality of drums of different Properties for different purposes and materials. Some owners also have a number of identical drums for a number of identical machines or one or more Drums as a reserve.

So far, the use of a drum of a certain diameter only possible on one machine. It was not possible, a drum screen with a specific screen diameter for one certain machine type to use on a different machine type, which was designed for a different drum size.

The owner now buys a new modern drum screen with larger drum diameter, so he can use the old drums Do not reuse, as these have a smaller screen diameter and also a smaller race diameter for the drive to have.

Although a trommel screen is known in the art become, used in the different sizes screen diameter can be, but with this machine it will achieved that the tread different in drum sieves Sieve sizes yet has the same large diameter. That means the owner when buying a larger machine the smaller drums can not continue to use, since these have too small a diameter of the tread. With a Such a machine, the owner can therefore only additional smaller drum screens with a correspondingly large running surface buy, but not with the purchase of a larger drum screen Continue to use the older smaller drum screens.

It is therefore the object of the present invention to provide another device with which drum screens different screen diameter can be used.

This object is achieved by the subject of the Claim 1 solved.

Preferred developments of the invention are the subject of Dependent claims.

The present invention according to claim 1 provides a screening machine available, which has a rack device. The rack means is provided with at least one support means provided for holding a drum. At least one proppant is in a first position for holding a drum one first diameter and in a second position to hold a drum of a second diameter formed.

The screening machine according to the invention has many advantages.

Characterized in that the Trommelsiebmaschine for receiving two drum diameter is suitable, further use (e.g. older) drums of smaller diameter, although the trommel screen also for the operation of drums is formed with a larger diameter. With the present Invention will be the (flexible) reuse of smaller drums allows. That was in the state of the art not possible in this way. That makes the cost-effective change a more modern and efficient facility possible, with the existing drums can continue to be used. Thereby will be significantly less investment in a system change due.

In a preferred embodiment of the invention, the or At least one support means for holding at least three or four drums with different diameters formed. Preferably, the support means also for holding or supporting suitable for even more different drum diameters be.

Preferably, at least two, preferably at least four, support means provided. This will be a particularly reliable Support of the drum achieved.

In a preferred embodiment, at least one Support means at least two support elements, preferably are designed as rolling elements. Rotatable support elements are very beneficial because it makes a simple and reliable rotatable support or a rotatable holding the drum allows becomes.

In a preferred embodiment of one or more of the above described embodiments of the invention is at least a support means received pivotally. If the proppant Support elements comprises, then the support elements are preferably with a swivel.

Preferably, at least one support means is designed such that the support means by pivoting from the first Position in at least the second position can be transferred. Also several positions are possible. Particularly preferred is that a simple return from the second to the first Position is possible, preferably by pivoting back. If two drum sieve sizes are receivable then it is preferable that a pivoting takes place by 180 °.

It is also possible that at least one support means displaced or is picked up by a recording spatially variable. For example, can be a displaceability instead of the pivoting be provided. It is also possible that in addition to pivoting a displacement of the proppant or the Supporting means is possible. Preferably, a shift occurs in the radial direction with respect to a drum, so that with linear displacement of several support means Intersection on the virtual central axis of the drum results.

By arranging the support means in a second receptacle can the device for receiving a different drum diameter to be converted. There, the proppants in suitable Attached manner, e.g. screwed or plugged and e.g. With provided a backup pin.

Preferably, the virtual central longitudinal axis of a male Drum independent of the drum diameter held substantially in the same place. That means, that two drums of different diameters substantially be kept concentric with each other. Be the drums supported on its outer diameter, the support point must higher for drums with a smaller diameter. This means that by transferring from the first to the second position or vice versa, the height of the support point or breakpoint is changed.

Preferably, a breakpoint is higher in the second position as in the first position.

In preferred embodiments, the rack means for Recording formed by at least one drum, which a Having diameters from a group of diameters, which at least the diameters 1.5 m and 1.8 m and 2 m as well 2.2 m. Particularly preferred is the inclusion of Drums of diameter 2 m and 2.2 m possible. Likewise preferred is the recording of drums of diameter 1.8 m and of diameter 2 m, or the inclusion of drums of the Diameter 1.5 m and diameter 1.8 m, or recording of drums of diameter 1,8 m and diameter 2,2 m. Also the inclusion of drums of different diameters, in particular, as are customary in the prior art, is preferred.

At this point it should be noted that under different Drum diameter in the meaning of this invention essential Differences in diameter are understood. Of the Difference of e.g. 1 cm in diameter is considered not essential considered. This is different for larger differences of 10 or 20 cm or more. Even 5 cm can be a substantial Mean difference.

Preferably, a housing is provided, which is a drum surrounds, at least partially, at least on the long sides. Preferably, on each longitudinal side in the direction of travel one Side wall provided, which substantially at least the covering the lateral area of the drum.

In a preferred embodiment of the (horizontal or radial) distance of the housing wall on a first longitudinal side larger than on the second long side. In the prior art an equal distance is provided on both longitudinal sides, ie between the respective drum outer wall and adjacent housing inner wall.

A different distance on both sides is very advantageous because during the rotation of the drum is through the in the drum arranged material conveyor, such. a Auger, the material to be screened on the first Long side with taken up. That's through the rotational movement conditionally. This sieved fine material passes through the Drum screen out through. The fine material then falls down the side wall and onto the drum conveyor belt for the fine material.

However, individual parts can get stuck in the screen, so that a portion of the respective parts protrudes outward. Therefore, on the first page on which the material should be in the drum is transported up (by taking the material Is) provided a sufficient distance from the housing wall be to avoid blocking. This page is here with first page. On the other hand, it is enough a much smaller distance to the housing wall, as in the Sieve wall existing material in the upper rotational range of the drum falls down again. Or the drum screen becomes by a possibly existing cleaning device, in the form e.g. a cleaning broom, of stuck material again freed. This can be done by the cleaning brush with from its bristles the sieve openings of the drum sieve of set Ingredients free. Overall, the different lateral distances a smaller overall width achieved, or it is a larger with the same overall width Drum diameter possible.

In one embodiment of the invention is a task bunker provided, which preferably as a Forderbandkassette having trained bunker conveyor belt.

Preferably, the bunker conveyor belt on the underside Drive means which cooperate with the drive roller. This is advantageous because so far in the prior art Drive roller transmitted over the belt tension the force. in the Area of the bunker conveyor belt is the force in the Usually difficult because the goods to be transported in general not pulled, but pushed.

This is because the bunker conveyor belt into the sieve drum protrudes to the material transport into the drum reliably to ensure and remember that the driven roller usually not inserted into the drum for space reasons becomes. That's why the other roller is driven now causes a pushing of the conveying material. Here are the Power relations not ideal. Therefore, drive means are on the underside of the bunker conveyor belt very advantageous, in particular when interacting with drive means on the drive roller.

Preferably, the drive means of the bunker conveyor belt is as Toothing or designed as studs.

Advantageously, at least one drive roller is a Gearing provided. Particularly preferred on the drive roller the bunker conveyor belt, in particular when the bunker conveyor belt having corresponding drive means.

In one embodiment of the invention is at the material outlet side the task bunker arranged a sealing ring is. The sealing ring seals the transition from the feed bunker towards the drum.

Preferably, at least one control device is for control the screening machine or at least parts thereof intended.

Advantageously, by means of or by means of at least one Control device at least the control and / or adjustment the conveying speed of at least one component possible. Particularly preferred is the control and / or adjustment the conveying speed of the bunker conveyor belt possible.

In a preferred embodiment is (at least) a drum drive provided, the (at least) a drive motor which is preferably a hydraulic motor. Possible is also an electric motor or other drive motor, as used in the prior art for such cases becomes.

Preferably, the drum drive causes a sieve operation Rotation of the drum in a clockwise direction, seen in the conveying direction of the material or bunker conveyor belt.

In a preferred embodiment of the invention comprises the Drum drive a roller chain. The roller chain is preferably with e.g. provided with right-angled fastening straps, as they are e.g. in DIN 8187 - ISO 606 are described. Preferably is every fourth chain link with a fastening tab equipped. But it can also every second, third or only every fifth, sixth or e.g. seventh chain link be equipped with a fastening strap. through Such link plates, the drive power is effective from transferred to the drum.

On the running surface of the drum on which the roller chain runs is preferable for noise reduction and better Transmission of drive power a power transmission layer arranged or applied with a higher coefficient of friction. For example the layer may consist of a rubber material. Other elastic materials or plastics are possible. The attachment tabs cause a larger area for power transmission.

Alternatively to a layer of a rubber material on the Drum outer surface or in addition to such Layer can be single or all chain straps respectively with an elastic foot or e.g. equipped with a rubber foot be to ensure an effective power transmission.

In a further development, the drive motor is mounted pivotably. Preferably, a position of the drive motor controllable by an adjusting device, which preferably a hydraulic adjusting device comprises.

In screening machines larger drum diameters are desirable, because with larger diameters the performance can be increased is. However, increasing drum diameter mean a big one constructive challenge, as the overall width at about 2.5 m is limited. The possible width is for mobile systems conditioned by the respective street width. At other road widths Other maximum drum diameters are possible.

In recent years, a drum screen with 2 m Drum diameter used. The development step of 1.8 m diameter to 2 m drum diameter is due to the maximum permissible total width very considerable, since the transport width The machine does not significantly exceed about 2.5 m may. It should be noted that the drum is still from surrounded by a housing. Furthermore, usually a side discharge belt provided on the housing, which the Width increased significantly.

In an advantageous development, a larger drum diameter allows for the same overall width.

For this purpose, the screening machine comprises e.g. a housing with a first Sidewall and a second side wall, between which a Drum is rotatably received. Here is a first distance a first side wall to the drum is larger than a second distance of a second side wall to the drum.

Below distance here is the shortest typical lateral or also to understand radial distance. In particular, hereby the typical lateral distance equal to the largest width of the Sieving machine, or the typical lateral distance equal to the largest drum width understood.

This embodiment has many advantages.

Through these adjustments, it has now succeeded, the drum diameter again significantly increase to 2.2 m. This will be the Performance of the plant, which is caused by the sieve area is significantly increased. The throughput to be screened Material is much higher.

On the drum side, which takes material up when turning, should the lateral distance have a sufficient degree, while the lateral distance on the other side is quite can be smaller.

In another embodiment, the mobile screening machine comprises a housing for receiving a drum. Furthermore, it is laterally on the housing at least one conveyor for discharging arranged by material. The lateral conveyor has an upper and a lower transport roller. It has the upper transport roller has a larger diameter than the lower transport roller.

Also with this configuration is a smaller overall width with the same drum diameter or a larger drum diameter possible with the same overall width.

Preferably, the upper transport roller is driven.

In a preferred embodiment, at least one upper Part of the lateral conveyor, e.g. in the form of a conveyor belt, retractable. Preferably, the upper part is for Transport foldable. Particularly preferred is the folded Part then during transport at least partially above the Drum arranged.

The frame device is preferably structured in such a way that a (virtual) central longitudinal axis of a drum laterally offset from a center line of the rack device is arranged in the longitudinal direction. That is advantageous because on the one side next to the drum, a lateral conveyor is provided. Then there is a laterally offset one Construction instead of a symmetrical structure advantageous, because the maximum lateral projection is limited.

In a further preferred embodiments of the invention may be various of the described embodiments and developments be combined.

Further advantages and applications of the present Invention will become apparent from the following embodiment, which will be explained with reference to the figures.

Fig. 1

eine erfindungsgemäße Siebmaschine in Transportstellung in einer perspektivischen Ansicht;

Fig. 2

die Siebmaschine nach Fig. 1 in Arbeitsstellung in einer perspektivischen Ansicht;

Fig. 3

eine große Siebtrommel in der Siebmaschine nach Fig. 1 in einer schematischen Vorderansicht;

Fig. 4

eine vergrößerte Darstellung einer Lagerschwinge zur Lagerung der großen Siebtrommel nach Fig. 3;

Fig. 5

einen Ausschnitt einer schematischen Vorderansicht einer kleineren Siebtrommel in der Siebmaschine nach Fig. 1;

Fig. 6

eine stark schematische Ansicht der Siebtrommel im Gehäuse der Siebmaschine nach Fig. 1;

Fig. 7

eine stark schematische Ansicht des Austragsförderbandes für Feinkorn der Siebmaschine nach Fig. 1;

Fig. 8

eine schematische Ansicht der Siebtrommel nach Fig. 1 mit dem Trommelantrieb in der Ruhestellung;

Fig. 9

eine schematische Ansicht der Siebtrommel nach Fig. 1 mit dem Trommelantrieb in der Eingriffsstellung; und

Fig. 10

eine vergrößerte schematische Ansicht des in Fig. 8 dargestellten Trommelantriebs in der Ruhestellung.

In the figures show:

Fig. 1

a screening machine according to the invention in transport position in a perspective view;

Fig. 2

the screening machine of Figure 1 in working position in a perspective view.

Fig. 3

a large screening drum in the screening machine of Figure 1 in a schematic front view.

Fig. 4

an enlarged view of a bearing rocker for supporting the large screen drum of Fig. 3;

Fig. 5

a detail of a schematic front view of a smaller screen drum in the screening machine of Fig. 1;

Fig. 6

a highly schematic view of the screen drum in the housing of the screening machine of Fig. 1;

Fig. 7

a highly schematic view of the discharge conveyor belt for fine grain of the screening machine of Fig. 1;

Fig. 8

a schematic view of the screen drum of Figure 1 with the drum drive in the rest position.

Fig. 9

a schematic view of the screen drum of Figure 1 with the drum drive in the engaged position. and

Fig. 10

an enlarged schematic view of the drum drive shown in Fig. 8 in the rest position.

The embodiment will now be described with reference to the figures described. FIG. 1 shows a mobile screening machine 1 in FIG Transport position 35 and in Figure 2 in the unfolded working position 36 is shown.

The trommel screen 1 has a frame 2 with wheels 42 on which the drum 4 is rotatably held. By Replacement of the drum 4, different drums 7, 8, as shown in Figures 3 and 5, with different large diameters are used. This is the embodiment as supporting rocker 3 running support means in FIG. 3 in the first position 5 for large drums and in FIG 5 shown in the second position 6 for smaller drums.

At a first end 43 of the trommel screen 1, the Total mobile, mobile, drum screen 1 in the Transport position 35 are attached to a vehicle.

At the first end 43 is the task bunker 17, the the bunker hopper 18 and the bunker conveyor belt 22. The Loading takes place e.g. by means of a wheel loader or an excavator (not shown) in the task bunker 17. Below the task bunker is the drive unit 19 of the Screening machine 1.

The bunker conveyor belt 22 is designed as a conveyor belt cassette, in which all drive elements such as drive roller, guide roller, Conveyor belt, gearbox and hydraulic motor etc. are integrated. The conveyor cassette is inserted into the bunker hopper 18 and fixed. The bunker conveyor has at the bottom Stollen 45, which engage in the drive roller, which also interlocked (not shown).

The bunker conveyor belt 22 projects into the drum 4 and reliably conveys the material to be screened into the drum 4 into it. At the material exit side of the task bunker 17 is attached to the bunker hopper 18, a sealing ring, the Bunker 17 seals to the screen drum 4 out. The tolerance is in the exemplary embodiment about 10 mm. Depending on the application can Larger or smaller tolerances are available.

The feed rate of the bunker conveyor belt 22 can in Dependence on the sieve size and the sieve material by means of a control device 49 can be set. The control device may include one or more potentiometers.

From the first end 43 of the screening machine in the direction of the second Ending 44, joins the task bunker 17 the screen drum 4 at.

The screen material coming from the hopper 17 falls into the screen drum 4. This rotates in operation at a speed from about 10 to 23 revolutions / min. One on the inside the screw conveyor introduced screw conveyor 50 takes over the material transport within the sieve drum. The Screw conveyor is welded in the embodiment.

Overall, the screening drum 4 consists of the perforated drum shell, the auger 50, the two races to rotatable holding, a drive section, with a rubber lining equipped, an inlet ring 51 in the beginning the drum and optionally one or more axial rings (not shown) for stabilizing and securing the drum in the axial direction.

By the rotation 30 of the drum 4, the screen material with taken down and falls down again at a certain point. The material in the drum 4 behaves in a sense similar to an overturning wave in the sea. From the back seen the material is in a range of 2 O'clock until 6 o'clock. The drum moves against in this view clockwise. Seen from the front in the conveying direction, so from the first end 43 toward the second end 44 seen, the material is located approximately in an angular range between 6 and 10 o'clock.

As can be seen in the schematic illustration according to FIG. 6, is located on the side of the side wall 12 a horizontal distance 15 between the drum 4 and the side wall 12 before. On the opposite side on the side wall 13 is the minimum horizontal distance 16 in front. Here in the embodiment the distance 16 is significantly smaller than the distance 15. The Distance can e.g. 80% or 50% or just 33% of the distance 15 be. As a result, valuable space is gained in width. Here it is so that the larger distance 15 on the side is present, transported on the conveyor material in the drum becomes.

The finer portion of the sieve material, the fine grain, falls through through the screen perforations, while the coarse part, the oversize, remains in the drum. The oversize is through the augers 50 towards the end of the drum and then out there promoted.

In the embodiment, the screen drum has a diameter of 2200 mm and a length of 5500 mm. The unperforated area has a length of approx. 320 mm at the front and at the back. In In this unperforated area are the rollers for rotatable support of the screening drum and the drive area with the rubber tire pad.

The drum is on four support means in the form of bearing rockers 3 stored. Each bearing rocker 3 has a pair of wheels with wheels 10 for rotatably supporting the screening drum 4. These pairs of wheels are rotatably received on the bearing rockers 3. Each bearing rocker 3 is on the frame 2 or the housing 11 pivotally mounted.

It is also possible to use only four carrying wheels 10. These are then attached to the frame 2 with a flange.

The drive of the drum 4 is done by means of a roller chain 31 at the on each fourth member two angled tabs (not shown) are located. These tabs are on the rubber pad 52 of the drum 4.

A drive sprocket (not shown) is with a motor connected. In the exemplary embodiment, the engine is a hydraulic motor 29 executed. This engine is mounted on a rotatably mounted Motor console or attached to a flange 41. Of the rotatably mounted motor flange or flange 41 is by means of an adjusting device moves, which in the embodiment as Hydraulic cylinder 33 is executed. The hydraulic cylinder 33 is attached on the one hand to the pivot point 40 on the flange 41 and on the other hand to the frame rotatable about a pivot point 55 attached. By the rotation of the engine console or the flange 41, the chain 31 is biased.

A cleaning brush 25 is provided in an upper area. This has the task of the screening drum 4 of attachments through sieve material at the holes and webs of the sieve drum to free. The cleaning brush 25 consists of a stored Wave, on the round broom discs with a plastic trim are raised. The cleaning brush 25 in total and its cleaning discs (the brooms) have no separate Drive, but are taken by the drum and set in rotation.

The plastic bristles of the round brush discs pierce the Sicblöcher and thus free them from dirt and adhesions. The bristles and brush discs wear out over time. To compensate for the wear and even at partially worn Bristle to a sufficient cleaning result achieve, the broom can be adjusted. In the embodiment This is done with the help of hydraulic cylinders.

The discharged from the drum fine material either directly or via chutes on the drum conveyor belt 20. This sits longitudinally under the drum and transports the fine material to the rear. There, the material is on a short cross conveyor 21 pass and then reaches the discharge conveyor 23 for fine grain, which with an inclination of approx. 30 ° is employed to the horizontal. Subsequently, the fine material poured freely on heap. The discharge conveyor 23 for fine grain is folded for transport to the screening machine. In addition, the upper part 34 of the conveyor belt still bent hydraulically and lays over the sieve drum.

In the illustrated embodiment, the discharge conveyor comprises 23 for fine grain, a lower transport roller 27 and an upper transport roller 26 serving as a drive roller. According to This embodiment, the roller 27 a clear smaller diameter 54 than the drive roller 26, which has a diameter 53.

The oversize material falls from the screen drum 4 on a longitudinal arranged discharge conveyor 24 for oversize. The conveyor belt has a slope of about 25 ° to the horizontal. The material falls free on heap at the end of the tape. This band will also folded up for transport and the upper part 46 buckled.

The primary drive of the screening machine is via an industrial diesel engine. The secondary drive of the individual components via hydraulic pumps attached to the diesel engine. Depending on the design, the diesel engine may have a different Have power, which is here at 90 kW.

It is possible to use sieve drums of different drum shell diameters and use different raceway diameter.

Given dimensions of the bunker conveyor belt 22 or bunker conveyor cassette, that makes certain positioning demands the screening drum, because the bunker conveyor belt 22nd must be introduced into the sieve drum. The free cross section the sieve drum at the level of bunker conveyor belt 22nd must be large enough to accommodate it.

This is usually guaranteed when the axial center axis the drums within the machine remain the same, independent from the diameter of the drum 7, 8.

Otherwise, also the lateral dimension of the bunker conveyor belt 22 be reduced, but this associated with capacity losses can be.

In the embodiment, by pivoting the bearing rockers 3 ensures that the (virtual) axial center axis 37 of drums with different diameters stays the same. Since the pivot points of the wheels 10 by the distance 47 offset from the Verschwenkungspunkt 14 arranged are, by pivoting the bearing rocker 3 by 180 ° a drum with a different by twice the distance 47 Radius recorded in register.

Each bearing rocker 3 has an impeller pair. The wheels 10 are mounted on the rotatable bearing rocker 3 and stored there. The pivot point 14 of the bearing rocker 3 and the Axes of the wheels 10 are not on a line but are arranged offset by the distance 47, in the embodiment 50 mm.

In the first position (see Figure 3), namely the position The larger drum contains the axles of the wheels below the pivot point of the bearing rocker 3. Should now one smaller drum are used, the bearing rocker is the third swiveled by 180 °. Now there are the axes of the races above the Verschwenkungspunktes 14 (see Figure 5). By the offset of two times 50 mm results in a radius change of 100 mm and a diameter change of 200 mm. When the first position is designed for a diameter of 2.2 m is, then the second position is to take a Drum of 2 m diameter suitable. The same applies to Drums with 1.8 m and 2 m diameter.

By adjusting the distance 47 to desired conditions (e.g., 1.5 m and 1.8 m diameter) may be for different Applications different bearing rockers 3 available be put.

Also possible is a swingarm, which has three wheels, which are arranged in a triangle to each other. The central one Verschwenkungspunkt 14 of such a bearing rocker 3 should then from all three axes of the wheels 10 a different Have distance. Now you can swing by each 120 ° the screening machine on the recording of a screening drum be prepared with one of three diameters.

The already described pivotally mounted drum drive 28 is biased by a hydraulic cylinder 33. Becomes the screening machine is started, an automatic, time-delayed starting of the individual components.

This is very advantageous because in particular untrained operators the individual components may be in an inappropriate condition Turn sequence on or off, e.g. the bunker conveyor belt when the machine was parked, so it can happen that the operator in the meantime from the bunker conveyor belt 22 into the drum 4 transport the material back in by shovel must, which is associated with a considerable amount of work and time can be.

To start, first the two discharge belts for the Fine grain and the oversize 23, 24 started, then the Cross conveyor belt 21 and then the drum conveyor belt 20, then the automatic chain tensioner (the hydraulic cylinder 33) of the screen drum drive 28, then the screen drum and finally, the bunker conveyor belt 22 of the feed bunker 17.

The shutdown takes place in reverse order, among other things to avoid the disadvantage described above.

The bias is done in the embodiment so that the Hydraulic cylinder 33 running clamping cylinder with a specific, predetermined pressure is applied. This will the drum drive 28 with the drive motor 29 from the rest position brought into the engaged position and the roller chain 31 excited. The flange 41 with the drive motor 29 is doing pivoted about the pivot point 32.

In the new condition of the chain drive is a medium or even a slight deflection of the hydraulic cylinder 33rd Due to the force of the hydraulic cylinder 33, the Roller chain 31 stretched. The biasing force is determined by the Working pressure of the hydraulic cylinder 33 conditionally.

Has after e.g. several days of operation, the roller chain 31 Lengthened, so when you start but always back to the desired Preload set. At an elongation of the roller chain 31, the hydraulic cylinder 33 moves only slightly further out until the counterforce of the hydraulic force of the hydraulic cylinder 33 holds the balance. So here lies a self adjusting system. This reduces the need for maintenance enormously. Also, the wear is lowered and the life elevated. Too little bias in the roller chain 31 can to a slippage of the chain and increased wear to lead.

In one embodiment, after tension of the hydraulic cylinder 33 and after the drum drive 28 in the engaged position was brought, then the pressure by means of a Directional valve locked. The hydraulic cylinder 33 and thus the drum drive 28 now remain in the engaged position 38, until the operation is terminated. During a business day or a continuous operating period, an elongation occurs the roller chain 31 usually not or only in negligible slight extent, so that the bias in the roller chain 31 is essentially preserved. Should be the bias Nevertheless, let off, by stopping and again Start the screening machine of the hydraulic cylinder 33 new be positioned so that then the desired bias is again present.

Alternatively, the pressure in the hydraulic circuit can be continuous or at predetermined periodic intervals with a Sensor (not shown) are measured. If then the measured Pressure falls below a certain level, is in one Embodiment of the pressure in the hydraulic circuit again Nominal level brought. The time intervals of the measuring points may also depend on the measured pressure. It is also possible that the time intervals from the load of the drum drive depend and e.g. is measured more often when a high Load is present.

In another preferred embodiment, the biasing force the chain is regulated by the pressure in the hydraulic circuit is maintained at a desired level. The absolute Pressure or the biasing force can in particular also by the Depend on the load of the drum drive and correlate with it.

In another embodiment, the hydraulic cylinder remains 33 during operation under pressure. Then a continuous Self-tension realized.

In all embodiments can in the circulation of the hydraulic cylinder 33 a spring 48 may be arranged, which in the embodiment as a hydraulic spring in the form of a nitrogen bubble is executed. This hydraulic spring 48 can be out of round compensate for the drum 4 and the chain drive 28.

An advantage of such a hydraulic spring 48 is that that the roller chain 31 always has the same bias. This contributes to an increase in the life of the entire Chain drive at.

If the screening machine 1 is switched off, the directional control valve is actuated and switch over. Now the hydraulic circuit of the hydraulic cylinder 33 unlocked, the cylinder moves to the rest position 39 and the chain 31 is relieved. Im relieved State, the chain 31 from the sprocket (not shown) be taken. This is e.g. necessary to the drum 4 too switch.

A second possibility is the hydraulic circuit of the Hydraulic cylinder 33 with the hydraulic circuit of the Antriebsmo-Lors 29 of the screen drum drive 28 to connect. So should the pressure in the drive motor 29 increases (e.g., through heavier Sieve material), the pressure of the hydraulic cylinder 33 is also increases and thereby the bias of the drive chain 31st

This load-dependent control circuit prevents slippage the drive chain 31 aut the drum 4, even under the toughest conditions.

Another advantage of hydraulic tensioning of the chain is that the drum is briefly removed, e.g. for maintenance purposes or can also run backwards longer.

Claims (12)

Screening machine (1), with: a rack means (2) provided with at least one support means (3) for holding a drum (4); characterized in that the support means are formed in a first position (5) for holding a drum of a first diameter (7), and in a second position (6) for holding a drum of a second diameter (8). A screening machine according to claim 1, characterized in that the support means (3) are designed to hold at least three, four or more drums (4) with different diameters. Screening machine according to Claim 1 or according to Claim 2, characterized in that at least two, preferably at least four, support means (3) are provided. Screening machine according to at least one of the preceding claims, characterized in that at least one support means (3) comprises at least two support elements (9), which are preferably formed as a rolling body (10). Screening machine according to at least one of the preceding claims, characterized in that at least one support means (3) is received pivotably and / or at least slidably received. Screening machine according to at least one of the preceding claims, characterized in that at least one support means (3) is designed such that the support means (3) can be transferred by pivoting from the first position (5) into at least the second position (6). A screening machine according to at least one of the preceding claims, characterized in that the frame device (2) is designed to receive at least one drum (4) which has a diameter of a group of diameters at least 1.5 m and 1, 8 m and 2 m and 2.2 m. Screening machine according to at least one of the preceding claims, characterized in that a housing (11) is provided which at least partially surrounds a drum (4) at least on the longitudinal sides (12, 13), wherein preferably the distance (15) of the housing wall to a first longitudinal side (12) is greater than on the second longitudinal side (13). Screening machine according to the preceding claim,
characterized in that a Bunkerförderband (22) is provided, which has on the underside with the drive roller cooperating drive means, wherein the drive means are preferably formed as a toothing and / or as studs and preferably at least one drive roller (26) has a toothing. Screening machine according to at least one of the preceding claims, characterized in that a control device (49) is provided. A screening machine according to at least one of the preceding claims, characterized by at least one conveying device (23) arranged laterally on the housing (11) for discharging material, which preferably has an upper and preferably a lower transporting roller (26, 27), the upper transporting roller ( 26) may have a larger diameter (53) than the lower transport roller (27). Screening machine according to at least one of the preceding claims, characterized in that the frame device (2) is structured in such a way that a central longitudinal axis (37) of a drum is arranged laterally offset relative to a center line of the frame device (2).

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