FI65925C - SAOLL AVSETT FOER SAOLLNING AV TRAEFLIS - Google Patents

Description

1 65925

The present invention relates to a screen for screening wood chips, in which the screen basket is divided into two overlapping balancing basket blocks, the first 5 of which are supported by at least two pairs of ropes or similar support members, the basket blocks being connected to each other by a drive member.

Cooking chips from the pulp industry are obtained from raw chips by separating the oversized fraction (sticks) and the chips. The oversized 10 verse is recovered by chipping it again. Chips are boiled either separately or together with cooking chips, but it is also very commonly used as a fuel. The chips are sorted by size by screening. The planes used in the screen are, for example, hole, closed, disc or helical planes.

15 The screen screening business aims for high speed for two reasons: 1. To increase screen capacity and 2. To keep screen levels open.

20 The opening of the sieve trays is hampered by pieces of wood and slats that get stuck in the holes in the sieve tray, as well as debris containing resin, moisture, snow, etc., which closes the most fine-meshed sieve trays.

The screening movement of the wood chips usually takes place in a horizontal plane, with 25 vertical crankshafts or an equivalent machine member. The maximum speed of the screening movement is usually always limited by the forces acting on the crankshaft bearings. Some of the forces are inevitable (e.g., horizontal mass forces of the screen basket), some are not (e.g., vertical forces of the screen basket and horizontal and vertical forces caused by the counter-50 weight). All current chip screens have the latter "parasitic forces" which reduce the maximum possible speed of the screen.

Finnish patent application 8l 2518 describes a screen which is divided into two separate overlapping 55 screen basket sections. Are the screen basket blocks supported so that they can move freely within a defined trajectory area? 65925 screen basket1 used by an actuator connecting the blocks. The drive member is, for example, a crankshaft, a connecting rod or a vibrator. The body blocks can move along opposite trajectories so that the body blocks, with their loads, continuously balance each other.

The present invention supports basket blocks of a screen basket divided into two overlapping, mutually balancing basket blocks, so that the bearing of the crankshaft connecting and driving the basket blocks is subjected to only 10 radial forces caused by the basket blocks. The screen according to the invention is mainly characterized in that the vertical plane defined by the pair of ropes or similar supporting members supporting the second body passes through the center of gravity of the latter second loaded body block or its distance from the center of gravity is at most I / ** from the actuator and center of gravity. the center of the bearing of the actuator supporting the other end of the second body block is in the same horizontal plane as the center of gravity of the loaded body block or its distance from the horizontal plane of the center of gravity is not more than 1 / ¾ of the distance between the centers of the two body blocks.

The invention will be described in more detail below with reference to the accompanying figures, in which Figure 1 shows a side view of a screen according to the invention, Figure 2 shows the same screen seen from the end and Figure 3 schematically shows the support of screen basket blocks.

The upper basket block 1 is formed by two overlapping screen planes 12 and 13. · The lower basket block 2 is formed by a chewing plane-30 ta 1¾ and the solid plane 15 below it. Umpitasc 15 is formed by bent plates. The basket blocks are k31 soaked and the chips to be screened are led to the top level 12 via the feed level 16. The oversized fraction exits the lower end of the upper level at point 17 and the accepted fraction from the lower ends of levels 13 and 1¾ at points 18 and 19. The debris is collected from the lower end of the closed level 15 at point 20.

5,65925

The body blocks 1 and 2 are connected by a crankshaft arranged between their upper ends so that the upper part 3 of the crankshaft is fastened in the body block 1 and the lower part 4 in the body block 2 by means of a self-aligning bearing 11. The crankshaft is preferably driven by 5 hydraulic motors. 1 with one pair of ropes 7 from the body 6, the other end 8 of the body block 1 resting on the upper part 3 of the crankshaft by a self-aligning bearing 11.

Figure 3 shows a side view of the screen of the suspension of the car-10 blocks 1 and 2 from the frame 6. As the crankshaft rotates and the loaded carcass blocks make a screening motion in the horizontal planes c and d, a dynamic force pair A rotates to their centers 9 and 10, causing h = H = A vertical height difference of priorities. If the 15 loaded basket blocks 1 are supported by a pair of ropes 7 from a transverse center of gravity 9 at a distance L from the upper part 3 of the crankshaft, its other end 8 rests on the bearing 11 of the upper end 3 of the crankshaft without being loaded.

If the center of the bearing 11 is still in the same horizontal plane-20 sa c as the center of gravity 9 of the loaded body block 1, the torque M = 0 caused by the upper dynamic force A at point 11, it further follows that the ropes 7 and bearing 11 are free of dynamic forces. The dynamic moment M = h x A caused by the force pair A is taken in its entirety by the rope pairs 5 of the body block 2.

Since the horizontal and vertical position of the center of gravity 9 of the loaded body block 1 moves somewhat due to the varying load of the body block and since the axial force - even a small one - is continuously parallel to the bearing operation, it is expedient to deviate from the theoretical center of gravity to the extent that said bearing enthusiasm is met. In this case, the basket block i a profitable pair of ropes? the distance of the defined vertical plane at the center of gravity of the body block is at most 1/4, in particular 1/6, preferably l / lh of the distance between the crank-kKsel and the center of gravity. The distance between the center of the bearing 11 of the crankshaft bearing the other end of the car.

5 As mentioned above, only the dynamic radial forces caused by the body blocks are subjected to the crankshaft bearing. It is free from all other "parasitic forces" exerting on the crank mechanism of the current screens - above all axial - and thus the screen 10 according to the invention makes it possible to achieve the highest possible speed in each case.

Claims (4)

5,65925 A screen for screening wood chips, wherein the screen basket is divided into two overlapping balancing basket blocks (1, 2), the first (2) of which is supported by at least two pairs of ropes (5) or similar support members, the basket blocks being connected to each other by a drive member ( 3, 4), characterized in that the vertical plane defined by the pair of ropes (7) supporting the second car block (1) or similar support members passes through the center of gravity (9) of the latter 10 second loaded car blocks (1) or at a distance from the center of gravity of at most 1/4 ) and the center of gravity of the bearing (11) supporting the other end of the latter second body block (1) is at the same time horizontal (15) soles (c) as the center of gravity (9) of the loaded body block (1) or its distance from the horizontal plane of the center of gravity. (c) is not more than 1/4 of the distance (h) between the centers of gravity (9, 10) of both body blocks (1, 2). Screen according to Claim 1, characterized in that the upper basket block (1) is supported by a single pair of ropes (7). A screen according to claim 2, wherein the basket blocks (1, 2) are in a tilted position, characterized in that the drive member (3, 4) is arranged between the upper ends of the screen blocks 25 (1, 2). Screen according to one of Claims 1 to 3, characterized in that the screen plane of the upper basket block (1) consists of overlapping coils.