Technical Field

The present invention concerns a vibrating screen having screening media in the form of a number of parallel screening mats.

Prior Art

In vibrating screens used for fractionation of for example crushed stones and gravel into fractions of stones with different sizes, screening media are used having screening holes for allowing stones smaller than the screening holes to pass through the holes. The screening media is placed on some kind of support structure, normally having the form of a grid. The screening media is a wearing part which is replaced from time to time. For many vibrating screens the screening media has the form of modules, including a support structure for the screening mat. When replacing the screening media the entire module is replaced. Thus, complete modules had to be stored and transported.

Summary of the Invention

One object of the present invention is to be able to use the same screening mat independently of the design and make of the vibrating screen. The dimensions of the screening mats are adapted to the actual vibrating screen.

According to the present invention carriers for screening mats are placed in existing vibrating screens. The carriers are adapted to the design of the support structure of the vibrating screen it is to be placed in. However, the part of each carrier to receive the screening mats is the same independently of the design of the vibrating screen. The same type of screening mat is used independently of the design of the vibrating screen.

The screening mats are cut into appropriate lengths before mounting in the vibrating screen. In that the screening mats may be cut into suitable lengths just before mounting, the screening media could be stored and transported rolled into a coil or in long lengths. Normally the carriers are not replaced when worn screening mats are replaced with new screening mats. Thus, compared to the previous systems, as indicated above, where the screening media is placed on a support to form a module, handling, such as transportation, storing and installation, is simplified.

Furthermore, mounting of the screening mats in the vibrating screen is made in an easy but yet reliable way, without any penetrating fastening means.

In the description the expressions "lower", "upper" and similar expressions are in view of the directions as shown in the Figs, and as normally used.

Further objects and advantages of the present invention will be obvious to a person skilled in the art when reading the detailed description below of different embodiments.

Brief Description of the Drawings

The invention will be described further below by way of example and with reference to the enclosed drawings. In the drawings:

Fig. 1 is a perspective view of a part of a vibrating screen including modular screening media of the present invention,

Fig. 2 is a cross sectional view illustrating fixation of the screening media to a carrier,

Fig. 3 is a cross sectional view of the carrier of Fig. 2,

Fig. 4 is a cross sectional view of the screening media of Figs. 1 and 2, and

Fig. 5 is a cross sectional view of a wedge according to the present invention.

Detailed Description of Embodiments In a vibrating screen carriers 1 are adapted to be received on an existing support structure. The screening media in the form of screening mats 2 are received on top of and fixed to the carriers 1 . A number of screening mats 2 placed side by side forms the screening deck of the vibrating screen. The existing support structure of a vibrating screen may have many different designs, and often forms a grid. In Fig. 1 the existing support structure is indicated by the reference sign 25. For fixation the ends of two adjacent screening mats 2 are received in a slot 6 in the carrier 1 and a wedge 3 is pressed down between the screening mats 2 in the slot 6 of the carrier 1 . The way of fixation will be described further below.

By means of the present invention the support structure of the vibrating screen is furnished with carriers 1 according to the present invention. The carriers 1 are adapted to be mounted on the actual vibrating screen. Then a number of screening mats 2 are mounted on the carriers 1 in the way as indicated above. The screening mats 2 are placed transversally to the direction of travel for the material on the vibrating screen, such as crushed stones, gravel etc., whereby the joint between adjacent screening mats 2 also are placed transversally to the direction of travel of the rocks, gravel etc. If the joints are placed in the same direction as the direction of travel of the rocks, gravel etc., there is a risk that some material will go along said joints and not be separated in an appropriate way.

The carriers 1 are elongated. Each carrier 1 has two upright beams 4, 5, between which the slot 6 is formed. The beams 4, 5 extend all of the length of the carrier 1 . In the upper part and as seen in cross section each beam 4, 5 has a number of protruding parts and grooves. Several of the protruding parts and the grooves are placed on the surfaces of the beams 4, 5 facing each other in each carrier 1 . Thus, said protruding parts and grooves are placed on two opposite sides of the slot 6 of the carrier 1 . At an upper outer corner, as seen in cross section, each beam 4, 5 has an outer protrusion 7 and at an upper inner corner it has an inner protrusion 8. In the upper surface of each beam 4, 5 an upper groove 10 is formed between the inner protrusion 8 and the outer protrusion 7. Each inner protrusion 8 forms both an upper surface of the inner corner and a vertical surface facing the other beam 4, 5 of the carrier 1 . At a distance downwards from the inner protrusion 8 a lower protrusion 9 is formed on the surface facing the other beam of the carrier 1 . Between the inner protrusion 8 and the lower protrusion 9 an inner groove 1 1 is formed.

Each screening mat 2 has opposite end parts 13, 14. The end parts 13, 14 are directed downwards from the screening mat 2. The lower ends of the end parts 13, 14 are chamfered 22 on the sides facing each other. At one end of each screening mat 2 a protection 15 projects downward from the screening mat and parallel with the end parts 13, 14. The protection 15 is placed at one end of the screening mat 2 and the distance between the protection and the adjacent end part 13 is adapted to the thickness of the beam 4, 5 of the carrier 1 , which adapted thickness is such that the beam 4, 5 can be received between the protection 15 and the end part 13. The protection 15 is intended to protect an outer surface 12 of the beam 5 of the carrier 1 most likely being hit by particles coming through the screening mat 2. The outside of respective end part 13, 14, i.e. the opposite sides of each screening mat 2, is generally vertical with a step. By the step form, an upper part 16 is formed extending less than a lower part 26. The forms of said outsides of the end parts 13, 14 are adapted to the form of the wedge 3.

The end parts 13, 14 have a number of protrusions and grooves complementary with the protrusions and grooves of the beams 4, 5. On the inside of each end part 13, 14 of the screening mat 2, and as seen in cross section, there are an upper protrusion 17 and a lower protrusion 18. Between the upper protrusion 17 and the lower protrusion 18 a lower groove 21 is formed. In an inner corner at each end part 13, 14 a corner groove 19 is formed. Adjacent the corner groove 19 a further, inner groove 20 is formed on a horizontal surface. The protrusions 17, 18 and grooves 19-21 of the end parts 13, 14 of the screen mat 2 extend all of the length of the screening mat 2.

The wedge 3 is an elongated, relatively thin part and having a length corresponding with the length of the carrier 1 and the screening mat 2. Seen in end view, as in Fig. 5, the wedge 3 has an upper part 23. The upper part 23 of the wedge 3 goes over into a lower part 24 by means of a chamfer, whereby the lower part 24 is thinner than the upper part 23 of the wedge 3. The lower part 24 has a number of horizontal or longitudinal crests on opposite sides, assisting in keeping the wedge 3 in place between the screening mats 2 after mounting. By means of the crests the friction between the wedge 3 and the adjacent screening mats is increased. The lower edge of the lower part 24 of the wedge 3 is pointed. Due to the pointed lower end and the thinner lower part 24 insertion of the wedge 3 is facilitated compared to if the wedge 3 would have a constant thickness.

In use one end part 13, 14 of a first screening mat 2 is placed inside the slot 6 of one carrier 1 , with the end part 13, 14 connected to one beam 4, 5 of the carrier 1 . In the shown embodiment the outer protrusion 7 at the outer corner of the beam 4, 5 is received in the inner groove 20 of the end part 13, 14. The inner protrusion 8 of the beam 4, 5 is received in the corner groove 19 of the end part 13, 14. The lower protrusion 9 of the beam 4, 5 is received in the lower groove 21 of the end part 13, 14. The upper protrusion 17 of the end part 13, 14 is received in the inner groove 1 1 of the beam 4, 5. The lower protrusion 18 of the end part 13, 14 is placed below the lower protrusion 9 of the beam 4, 5. The cooperating protrusions and grooves are placed abutting each other. On the vertical connection between the end part 13, 14 of the screening mat 2 and the beam 4, 5 of the carrier 1 , two protruding parts of respective part is placed below protruding parts of the other part.

After placing one end part of a first screening mat 2 inside the slot 6 of the carrier, an end part 13, 14 of a second screening mat 2 is placed inside the slot 6 of the carrier 1 . The corresponding protrusions and grooves of the end part 13, 14 of the second mat 2 and the beam 4, 5 of the carrier 1 cooperates in the same way as described above for the end part 13, 14 of the first screening mat 2 and the beam 4, 5 of the carrier 1 . The protrusions are received with a force fit in respective grooves. In each carrier 1 one end part 13 of one screening mat 2 having the adjacent protection 15 and one end part 14 of another screening mat 2 with no adjacent protection are placed. The protection 15 is placed on the beam 4, 5 directed against the direction of motion of the gravel etc. Said beam 4, 5 directed against the direction of motion of the gravel etc. risk to be hit by separated fractions.

Finally, the wedge 3 is pressed down between the end parts 13, 14 of the two screening mats 2 received inside the carrier 1 . Due to the form of the wedge 3, having a thinner lower part 24 it is easy to press down the wedge 3 a first distance. For the final pressing down of the wedge 3 a hammer or the like is normally used. The upper part 23 and lower part 24 of the wedge 3 will abut the upper parts 16 and lower parts 26, respectively, on the outside of the two screening mats 2 received in the slot 6 of the carrier 1 . By means of the wedge 3 the protrusions of the end parts 13, 14 of the two screening mats 2 and of the beams 4, 5 of the carrier 1 are forcibly pressed into the grooves of the beams 4, 5 of the carrier 1 and the grooves of the end parts 13, 14 of the screening mats 2, respectively. Thus, by the cooperation of the grooves and protrusions of respective part and the wedge 1 the ends of the two screening mats 2 are fixed to the carrier 1 . The fixation is made without the use of any penetrating fastening means.

After mounting the inner protrusions 8 and lower protrusions 9 of the beams 4, 5 and the upper protrusions 17 and lower protrusions 18 of the end parts 13, 14 of the screening mats 2 are placed abutting each other at alternating heights. For each contact surface between a beam 4, 5 and an end part 13, 14 the inner protrusion 8 of the beam 4, 5 is placed uppermost followed downwardly of the upper protrusion 17 of the end part 13, 14, the lower protrusion 9 of the beam and finally the lower protrusion 18 of the end part 13, 14.

A person skilled in the art realises that the exact form and placement of the protrusions and grooves of the end parts 13, 14 of the screening mats 2 and the beams 4, 5 of the carriers 1 may vary. However, according to the present invention it is beneficial if at least two protruding parts of the end parts 13, 14 of the screening mats 2 and the beams 4, 5 of the carriers 1 , respectively, are placed under and abutting two protruding parts of the adjacent beam 4, 5 and end part 13, 14, respectively.

The screening mats 2 may be fabricated by extrusions and may be reinforced by means of fibres integrated in the extrusion material. The openings of the screening mats 2 are given by punching. Normally, the extruded screening mats 2 are relatively long and may be transported and stored in a form rolled together into a coil. In time of use an appropriate length of the screening mat is rolled out and then cut, perpendicular to the end parts 13, 14. The extruded and cut screening mats 2 are recyclable.

The disclosures in the Swedish patent application No. 1050201 -1 , from which this application claims priority, are incorporated herein by reference.