DE2154784A1 - Tensioning vibrating sieve - by controlled stresses in warp wires - Google Patents

Abstract

A method for tensioning steel mesh sieves intended to be vibrated by impact transversely to the sieve surface. The steel mesh is clamped into the sieve frame, either tension-free or slightly pre-tensioned by hand in the weft direction; it is then clamped along both sides and one end, the weft tensile stress ds is measured and finaly the warp is tensioned to the volume delta k where delta k1 = delta k = delta k2, delta k1 = -delta s/3 + 10 Kpmm-2 and delta k2 = -delta s/3 + 12Kpmm-2. The second end is then clamped. The prefd. tensioning appts. uses a number of bolts, each tightened up against a helical spring, which tighten the warp wires in grps.

Description

Method and device for bathing 8-tray screen fabrics The invention relates to a method and a device for tensioning 8tahlsieboffe for Sieving machines, whose sieve mesh is made by pushers acting perpendicular to the sieve surface vibrate.

It is known that in screening machines with a slide drive one or more superimposed screen mesh are clamped at their edges. There are Construction methods in which the screen mesh is not pre-tensioned at all and construction methods, where the usually rectangular screen mesh in one or two directions be biased.

For this purpose, clamping devices are known which are attached to the screening machine are and the sieve fabric is stretched or firmly clamped during operation keep.

Also known is the tensioning of the sieve fabric with the aid of tensions and that after the tensioning, the screen mesh is placed by clamping strips.

The known methods have the disadvantage that the screen mesh without Knowledge of the applied clamping forces can be clamped in an undefined manner or partially Tensioning is completely dispensed with. Are sieve fabrics, especially fine sieve fabrics, Tensioned too high, so it flirts in connection with the vibrating stress of the sieve mesh to premature destruction.

If, on the other hand, the screen mesh is only stretched very slightly or not at all, This is what happens with sieving machines, the sieve mesh of which is caused to vibrate by a ram become completely uncontrollable vibrations of the sieve fabric. Areas with low sieve amplitude and consequently inadequate sieve throughput capacity Areas with extremely large sieve amplitudes, which means very high bending loads of the screen mesh and thus has frequent screen mesh breaks to the Bolge. It also comes to form knot lines, which are unstable, on the screen mesh surface and run along and also the external expression of extremely high strain on the sieve mesh are. These known screen tensioning methods and devices do not allow either optimal sieving throughput of the sieving machine still optimal standing sides of the sieve mesh.

The purpose of the invention is to achieve an optimal sieve throughput to achieve the greatest possible protection of the steel mesh.

This gives rise to the task of tensioning the steel mesh so that the static preload is a minimum and yet uncontrollable oscillation states of the steel mesh with knot line formation do not occur.

It has now been found that for the vibration behavior of the steel mesh the tension of the warp threads is of decisive influence during the tensioning the weft thread is of secondary importance.

The invention therefore includes a method for tensioning steel mesh for screening machines, aeren mesh are set in motion by plungers acting perpendicularly to the screen surface, which consists in that the steel mesh to be tensioned after being placed on the screen frame is smoothed tension-free by hand or in the direction of its shot 'äden is slightly pretensioned, then clamped at its side edges and on one end edge on the Siebrabaen and the weft thread tension ## is determined and then the warp threads are grasped at their still free end and tensioned so that their Rpamung ## is in the area , in which and are, after which the second end edge of the steel mesh is clamped on the screen frame.

It is advantageous to tension the warp threads by gripping them in groups the warp thread ends made by means of a machine-external tensioning device.

According to the invention, the clamping device consists of a counter the bar supporting the screen frame, which is supported by several sliding clamping bolts is penetrated, at the sieve-side ends short spam strips in groups Capture the warp threads are hinged, and the other end of them on the bar supporting coil springs is surrounded, which can be read in the desired on a scale Clamping force are adjustable.

Those achieved by the method and apparatus according to the invention 'Advantages are that now optimal service life of the screen mesh and optimal Sieve throughput can be achieved. This is very important, especially when the service life and performance of the screening machines are decisive for effectiveness large technological apparatus: chains are.

The invention is to be closer to an exemplary embodiment below explained. The associated drawing shows a plan view in FIG the clamping device according to the invention.

Fig. 2 shows a cross section through the clamping device.

A steel screen fabric 2 deposited on the screen frame 1 is made by means of a bar 3 that extends over the entire width is clamped onto the screen frame 1. The clamping device is supported with a frame 4 against the screen frame 1, while short clamping bars 5, which are rotatably mounted on clamping bolts 6, preferably through Clamp the steel screen mesh 2. When tightening a chip nut 7 is the steel screen mesh 2 is tensioned, the tensioning force from the tensioning nut 7 being applied a helical spring 8 is placed on the frame 4 and on the screen frame 1. The compression of a helical spring 8 is a direct measure of the steel mesh tension and can expediently on a scale that is attached to the clamping bolt 6, can be read. After reaching an equal over the entire width of the steel mesh The steel screen fabric 2 is feßgeklemat with the aid of the bar 9 and the machine-external clamping device is removed.

In the case of slide vibrating screening machines, it is expedient to remove the slide plate 10 and to loosen the longitudinal strips 11 during the screen tensioning. First after the target screen tension has been reached, the ram plate 10 and strips 9 are clamped in place.

Claims (3)

Pat entansoriic he: 1. A method for tensioning steel meshes for screening machines, the meshes of which are set in vibration by plungers acting perpendicular to the screen surface, characterized in that the steel mesh to be tensioned (2) after being placed on the screen frame (1) is slightly pretensioned or in the direction of its weft threads is smoothed tension-free by hand, then clamped at its side edges and at one end edge on the screen frame (1) and the weft thread tension ds is determined and then the warp threads are detected at their still free end and tensioned so that their tension 'the value assumes in which and is, after which the second end edge of the steel sieve fabric is clamped on the sieve frame (1). 2. Process for sapnnen of steel screen fabrics for screening machines according to Claim (1), characterized in that the Eettfadensension by group-wise Detection of the Eettradenenden made by means of a machine-external clamping device will. 3. Device for adjusting the warp thread tension and, if necessary Weft tension of steel mesh for achieving high throughput according to claim 1, characterized in that a machine-external clamping device (4; 5; 6; 7; 8) has many short clamping strips (5) which can be rotated on axially displaceable Clamping bolts (6) are mounted and via coil springs (8), which are located on the frame (4) are adjustable in the desired clamping force readable on a scale.