WO1996012835A1

WO1996012835A1 - An apparatus for separating and mixing particle-like material tending to form accumulations

Info

Publication number: WO1996012835A1
Application number: PCT/FI1995/000573
Authority: WO
Inventors: Jorma Nieminen
Original assignee: Valmet Corporation
Priority date: 1994-10-19
Filing date: 1995-10-18
Publication date: 1996-05-02
Also published as: AU3701095A; FI944913A; FI97628C; FI944913A0; FI97628B

Abstract

An apparatus for separating and mixing particle-like material tending to form accumulations, particularly fibrous material, before formation of a product comprises an endless conveying surface (2) equipped with gripping means, such as pins or the like, the inlet side of the conveying surface (2) being provided with a feeding device for feeding substantially untreated particles at a feeding point (A) onto the conveying surface (2). The outlet side of the conveying surface (2) is provided with a channel (3) for conveying particles by means of a flow (S) of a medium, such as air, to product formation. The apparatus is equipped, after the feeding device (1) in the direction of motion of the conveying surface (2), with a second endless conveying surface (4a) provided with gripping means, such as pins or the like, the second conveying surface (4a) forming together with the first conveying surface (2) a passage (5a) between the opposing conveying surfaces for separating and mixing the particles.

Description

An apparatus for separating and mixing particle-like material tending to form accumulations

The invention relates to an apparatus for separating and mixing parti¬ cle-like material as disclosed in the preamble of the appended claim 1.

In particular, the invention is intended for separating and mixing fibrous material, particularly a material with two different fibre types, such as fibre of vegetable origin and synthetic fibre.

British Patent GB-1 154 324 discloses an apparatus in which the fibres are brought by a feeding device between feed rolls which feed the fi¬ bres onto the surface of a rotating drum equipped with pins, from which the fibres are further carried with an air flow through an air channel, the drum periphery being in contact with the air channel for a short distance forward from the inlet point of the fibres. The air flow in the air channel carries the fibres further to mat formation.

The fibres treated with the apparatus according to the above-mentioned patent are short mineral fibres which are relatively homogeneous. Such fibres are usually easy to separate from each other and to mix together in order to avoid fibre accumulations or bundles impairing the quality of the product.

The purpose of the invention is to present an apparatus, whereby for improving the homogeneousity of the product, it is possible to separate particularly fibres of different types, e.g. of different materials, from each other and to mix them together. However, the invention is also suitable for treating a material containing the same fibre type, and gen¬ erally for treating any particle-like material where the particles tend to form accumulations impairing the quality of the final product. For achieving this purpose, the apparatus according to the invention is pri¬ marily characterized in what is presented in the characterizing part of the appended claim 1. The material can be well "opened" and mixed by carrying them into a passage between two conveying surfaces, where the particles are transferred from the gripping means of the first conveying surface to the gripping means of the second conveying sur- face, e.g. between a large drum equipped with pins and a smaller pinned roll rotating at differing peripheral speeds, from the drum to the roll.

With regard to some advantageous embodiments of the invention, ref¬ erence is also made to the appended dependent claims 2 — 19 and to the specification below.

In the following, the invention will be described more closely with refer- ence to the appended drawings, in which

Fig. 1 is a side view of the apparatus according to the invention,

Fig. 2 shows the entity of different conveying surfaces in a larger scale, and

Fig. 3 shows the gripping means of the conveying surfaces in a larger scale.

Figure 1 is a side view of the apparatus according to the invention. The apparatus is placed in a frame 1 provided with a feeding device 1 for supplying fibres. The feeding device 1 shown in Fig. 1 comprises an endless conveyor belt 1a followed by a set of rolls 1b, i.e. four pinned rolls, arranged pairwise in opposite positions, wherein they form a feeding passage therebetween for feeding the fibres supplied by the conveyor belt 1 towards the periphery of a large feeding drum 12. The first pair of feeding rolls, between which the feeding passage is formed, rotates slower than the second pair, whereby the speed of fibres will increase towards the drum 12. The pins of the rolls are in an inclined position opposite to the direction of rotation, and the distance between their points in the feeding passage is ca. 1 mm. The distance between the points of the pins on rolls of different pairs next to each other in the feeding direction is also ca. 1 mm.

The fibres are supplied onto the feeding conveyor 1a by some suitable dosing arrangement which will not be described more closely herein, because it is not part of the invention. Next to the set of rolls 1b, a feeding drum 12 with a large diameter is journalled to rotate in the frame of the apparatus, the surface of the ^' feeding drum 12 being equipped with gripping means which are inclined to the direction of movement and are capable of receiving at a feeding point A the fibre material fed by the set of rolls 1 b from between the rolls, and of carrying it forward along the periphery of the drum in the direction of rotation. Thus the periphery of the drum forms an endless conveying surface 2. After the feeding point of the feeding device 1 in the direction of rotation, at a short distance from the same, there are three pinned rolls 15, 14, 13, which are placed one after the other near the peripheral surface of the drum so that short passages 5c, 5b, 5a are formed between the respective peripheral roll surface closest to the drum 12 and the peripheral surface of the feeding drum 12, for separating and mixing the fibres. The feeding drum 12 is arranged to rotate at a high peripheral speed anticlockwise seen in Fig. 1 , and the rolls 15, 14, 13 at a slower speed clockwise, i.e. in the opposite direc¬ tion of rotation, wherein at the passages 5c, 5b, 5a the surface of the drum 12 and the respective closest surface of the roll 15, 14 or 13 move in the same direction.

Figure 2 shows the entity formed by the rolls in more detail. The three rolls 15, 14, 13 are close to each other in the direction of rotation of the drum, whereby passages 8 are formed also between them. In the pas¬ sage 5c accomplished by the first roll 15 in the moving direction on the conveying surface 2, the large motion difference between the conveying surface 2 and the surface of the roll 15 will tear out fibre bundles and part of the fibres will be transferred onto the surface of the roll 15, be¬ cause the roll 15 with a slower peripheral speed is capable of receiving and carrying fibres with its pins pointing upstream of the conveying surface 2. The clearance between the points of the pins of the opposing surfaces in this passage 5c is less than 2.0 mm, for example ca. 0.7 — 1.0 mm. The fibres carried by the roll 15 move close to the sur¬ face of the next roll 14 which in this passage 8 between the rolls has movement in an opposite direction, i.e. towards the drum 12. The fibres are brought with the pins of this latter roll 14, pointing in the direction of rotation, into a movement further towards the drum 12. In the pas¬ sage 5b between the roll 14 and the drum 12, the fibres are brought further with the pins of the drum 12 pointing in its direction of rotation. The well-opened, spongy fibre material will adhere well to the pins of the opposing surface in its passages, provided that the motion differ¬ ence of the surfaces and the orientation of pins are suitable, whereas a less opened fibre will be carried further along in the pins of the same surface. In the last passage 5a between the third roll 13 and the drum 12, there is a point B where the fibres brought by the drum 2 can be transferred to the pins of the slower-rotating roll 13, pointing oppo¬ site to its direction of rotation. In the direction of rotation after the point B, the periphery of the drum 2 and the periphery of the roll 13 have each a point where the peripheral surfaces of the drum and the roll are open to an elongate channel 3 which is closed in other parts and in which there is a flow of a medium, preferably air, entraining suf¬ ficiently well opened fibres therewith. As shown in Fig. 1 , the channel 3 extends approximately tangentially in relation to the drum 12, in an in- dined manner from above downwards, and it carries the fibres further to mat formation which can be implemented by any known method. The channel 3 can be e.g. on the suction side of a blower, whereby this blower is arranged to blow the well-opened fibres into further process¬ ing.

In the following, the behaviour of the material to be processed will be described more closely from the step when the material has advanced to the vicinity of the channel 3 in the direction of the periphery of the drum 12.

As mentioned above, the peripheral surface of the drum 12 forms a long endless conveying surface with gripping means, such as suitably shaped pins, protruding therefrom in an inclined manner and pointing in the direction of its motion. When the particle-like material has advanced into the narrow passage 5a between the last roll 13 and the drum 12, it will come to the action zone of the gripping means protruding from the second endless conveying surface 4a formed by the peripheral surface of this roll 13. At the passage 5a, the direction of motion of the conveying surfaces 2, 4a is the same, whereas the speed of the conveying surface 2 is considerably, preferably at least ten times higher. In the direction of motion of the surfaces, the passage 5a opens towards the channel 3 obliquely from behind in relation to the flowing direction of the medium flow S. The gripping means protruding from the second conveying surface 4a point opposite to the direction of motion of the surface in the passage 5a. A sufficiently loose or "opened" ma- ^' terial will be transferred at point B in the passage 5a to the gripping means of the second conveying surface 4a, provided that it is within their reach. The distance between the points of the gripping means in the passage can be less than 1 mm, for example 0.3 — 0.5 mm. Point B of the conveying surface 4a will be followed in the direction of motion by point C, where the conveying surface 4a extends tangentially in rela¬ tion to the longitudinal direction of the channel and the medium flow S in the channel 3 and is in direct contact with the channel 3. At this point, the direction of motion of the conveying surface 4a has changed be¬ cause of the rotational movement of the roll 13 so that the gripping means point in the direction of the medium flow S. The medium flow S in channel 3 sweeps said second conveying surface 4a, whereby suffi- ciently loose and sufficiently light-weight material will be detached from the gripping means and be carried away with the flow S. The conveying surface 4a will thus retain material which is still too heavy to be transferred by the effect of the medium flow S off the gripping means, i.e. the particles, such as fibres, are still partly adhered to each other.

After the passage 5a, the conveying surface 2 has a region around the point located tangentially to the flow S, where it is in direct contact with the channel 3, and the flow therein is capable of carrying away particles left in the conveying surface 2. In this way, the conveying surfaces 4a and 2 are arranged to supply particles directly into the flow in the chan¬ nel 3. In case the material to be conveyed contains material of varying size, it can be fed into the flow 3 in the desired ratio. Particles with the largest dimensions or size come more easily to the range of action of the second conveying surface 4 in the passage 5a, whereby they are conveyed with it to the point where they fall off to the flow S. Smaller particles, in turn, tend to remain between the gripping means of the first conveying surface 2 and are detached out into the air flow at a point after the passage 5a in the direction of rotation. For example in the case of fibres, shorter fibres remain between the gripping means of the first conveying surface in the passage 5a, whereas longer fibres which are usually more crimpy, protrude more, whereby they adhere more easily to the gripping means, pointing opposite to the direction of mo¬ tion, of the second conveying surface 4a moving more slowly. By re- leasing particles from the first conveying surface 4a into the flow S, it is also possible to increase the capacity and to avoid excessive commi¬ nution of particles during their circulation in addition to the fact that par¬ ticles of different sizes are included in the product, which is often pre- ferred in connection with the manufacture of mat-like and plate-like products.

The desired ratio can be influenced by selecting the length of the grip¬ ping means of the surfaces 2 and 4a, as well as by adjusting the clear- ance between the points of the gripping means in the passage 5a. Also orientation of the gripping means of the second conveying surface 4a will affect the distribution of particles in the passage 5a.

A circulation path for these adhered particles begins from the pas- sage 5a. In this circulation path, the particles are carried with the grip¬ ping means of the second conveying surface 4a into the vicinity of a third conveying surface 4b consisting of the peripheral surface of the preceding roll 14. At the narrowest point between the second conveying surface 4a and the third conveying surface 4b, i.e. in passage 8, there is a transfer point D where the third conveying surface 4b moves opposite to the direction of motion of the second conveying surface 4a and receives the particles into its gripping means pointing in the direc¬ tion of motion of the conveying surface 4b. At this point, the moving speed of the third conveying surface 4b is advantageously higher than the moving speed of the second conveying surface 4a. In the pas¬ sage 8, the distance between the points of the gripping means is less than 1 mm, for example 0.5 mm. With this third conveying surface 4b, the particles are carried through the passage 8 between a conveying surface 4c, conducting the pre-releasing of particles, and the third con- veying surface 4b. This conveying surface 4c for conducting the pre- releasing consists of the peripheral surface of the above-mentioned roll 15, and its motion in the passage 8 is reverse to the motion of the third conveying surface 4b, and its gripping means are directed with a negative rake, opposite to the direction of motion of the conveying sur- face 4c. In this passage 8, the gripping means of the third conveying surface 4b, thanks to their orientation with a positive rake, catch also those particles which have been carried in the pre-releasing with the ₇

conveying surface 4c from the passage 5c between the first conveying surface 2 and the conveying surface 4c.

With the motion of the third conveying surface 4b, the particles are car- ried after the passage 8 again near the first conveying surface 2 into the passage 5b formed between the third conveying surface 4b and the first conveying surface 2. In this passage, the directions of motion of the conveying surfaces are parallel, and the distance between the points of the gripping means can be less than 1 mm, for example ca. 0.5 mm. Since the gripping means of the third conveying surface 4b point in the same direction as the gripping means of the first conveying surface 2, they can deliver particles in the passage 5b to the gripping means of the first conveying surface 2 with a higher speed of motion, these grip¬ ping means pointing at the direction of motion of the conveying sur- face 2.

In Fig. 2, the circulation path is shown schematically by broken lines, and after this circulation path the particles are sufficiently loose so that in the passage 5a, upon their movement onto the second conveying surface 4a, they are sufficiently separate from each other so that they can be carried away with the medium flow S at point C.

The speeds of motion of the conveying surfaces 2, 4a, 4b and 4c are advantageously arranged so that the first conveying surface 2 has the highest speed of motion, and of the second conveying surface 4a, the third conveying surface 4b and the conveying surface 4c for pre-releas¬ ing, the third conveying surface 4b has the highest speed of motion. The speed of motion of the first conveying surface 2 can be e.g. 1600 m/min, that of the second conveying surface 4a ca. 35 — 40 m/min, that of the third conveying surface 4b ca. 100 m/min, and that of the conveying surface 4c for pre-releasing ca. 30 m/min, i.e. lowest compared with the others.

The apparatus has also another circulation path for those particles not carried away with the medium flow S. Those particles which are not sufficiently loose to be capable of adhering to the gripping means of the second conveying surface 4a or which are sufficiently small, are con¬ veyed along the first conveying surface 2, i.e. the peripheral surface of the drum 12. From this peripheral surface after the passage 5a, suffi¬ ciently loose particles can still be carried away with the medium flow S. ^■ The lower side of the peripheral surface is covered with a shield 7 for preventing the particles from falling down. The shield 7 ends above the first end of a returning conveyor 6, where the particles either fall onto the returning conveyor 6 or are carried back to the feeding point A past the lower feeding roll of the second pair of the set of rolls 1b moving before the feeding point A of the conveyor 1 in the rotational direction of the drum, opposite the surface of the drum 12. The returning conveyor 6 consists of an endless conveyor belt, with the end of the fibre-returning section revolving together with the first end of the feeding conveyor 1a against the roll guiding the first end of the feeding conveyor, whereby the fibres are returned between the belts of the conveyor 1a and the returning conveyor 6 back onto the feeding conveyor 1a.

Figure 1 shows also how the rolls 15, 14, 13 are joumalled rotatably in pieces 9, the position of which can be changed in the direction of the periphery of the drum 2 in order to change the location of rolls 15, 14, 13 in relation to each other and their absolute location in relation to the drum 12. This is achieved by arranging the pieces 9 at their ends on the side of the rolls to be in contact with adjusting means 9a fixed in the frame of the apparatus, and by arranging the pieces at their opposite ends to rotate in relation to the rotational axis of the drum 2. Further¬ more, the rolls 15, 14, 13 can be moved in the direction of height of the pieces 9, whereby also the distance between them and the drum 2, i.e. the width of the passages 5c, 5b, 5a can be fine-adjusted. By this ar¬ rangement, it is possible e.g. to arrange the location of the rolls 15, 14, 13 so that the width of the passages 5c, 5b, 5a changes in the rota¬ tional direction of the drum 2. The width of the passages will depend on the material to be treated, but their relative widths are arranged advan¬ tageously so that they decrease in the rotational direction of the drum 2. The fine adjustment of the width of the passages 8 between the rolls, in turn, can be made by turning the pieces 9 in relation to the rotational axis of the drum 12.

Figure 1 shows also the power transmission arrangements. The large drum 12 is rotated by a motor M1 of its own, which is fixed to the frame of the apparatus. It can be a motor with a constant rotational speed. The rolls 15, 14, 13, in turn, are driven with a second motor M2, also fixed to the frame of the apparatus. The rotational speed of this motor is variable; it can be e.g. an electric motor controllable with an AC in¬ verter. Also the movement of the feeding device 1 is achieved by using the second motor M2. The rolls 15, 14, 13 and the feeding device 1 are coupled to the same driving motor M2 so that an endless transmission element 10, such as a belt, chain or the like runs via the rotational axis of the rolls of the set of rolls 1 b and via the rotational axis of the driving roll of the conveyor belt 1a, and an endless transmission element 11 rotating the rolls 15 and 13, in turn, is passed via the rotational axis of one roll in the set of rolls 1 b, whereby it is in a power transmission con¬ nection via this roll to the transmission element 10 running via the driv¬ ing motor M2. Further, a second endless transmission element is used, running via the opposite end of one roll of the set of rolls 1 b to the other side of the middle roll 14 with such a transmission ratio that a higher peripheral speed is achieved on this roll 14.

As presented above in connection with describing the speeds of motion, the peripheral speed of the feeding drum 12 is considerably higher than the peripheral speeds of the rolls 15, 14, 13. The diameter of the feed¬ ing drum 12 can be e.g. 600 mm and the operating speed 800 rpm, whereby the peripheral speed is 1600 m/min. The peripheral speeds of the rolls 15, 14, 13 can vary between 30 and 100 m/min. The peripheral speeds are arranged advantageously so that the middle roll 14 is the fastest.

Figure 3 shows in more detail the surface structure of the conveying surfaces, i.e. the peripheral surfaces of the drum 12 and the rolls 15, 14, 13. The gripping means can be pins with a height of about 5 mm and the shape of a saw tooth, their bases in the direction of motion having a length of ca. 3 to 4 mm and a width of ca. 0.8 to 1 mm. The pitch of the pins is sufficiently close, for example ca. 0.5 to 1.0 cm in the direction of length (direction of motion) and ca. 1.2 to 2.0 cm in the direction of width (distances between the points).

The pins can be arranged on the surfaces by coating them with suitable pin clothings. One edge of the pins is inclined at a suitable acute angle α to the normal of the surface, i.e. with respect to the tangent of the peripheral surface, either towards or opposite to the direction of motion, as described above. This angle is generally about 10° in the conveying surfaces, but in the second conveying surface 4a it can be about 20 to 30°.

The invention is particularly suitable for treatment of a blend containing two materials with different properties, such as vegetable-based fibre and synthetic fibre, for example blends of wood fibre and thermoplastic binding fibre, or inorganic fibre and synthetic fibre, for example mixtures of mineral fibre and thermoplastic binding fibre.

Claims

Claims:

1. An apparatus for separating and mixing particle-like material tending to form accumulations, particularly fibrous material, before formation of a product of the particles of the material, the apparatus comprising an endless conveying surface (2) equipped with gripping means, such as pins or the like, the inlet side of the conveying sur¬ face (2) being provided with a feeding device (1) for feeding substan¬ tially untreated particles at a feeding point (A) onto the conveying sur- face (2) and the outlet side being provided with a channel (3) for con¬ veying particles by means of a flow (S) of a medium, such as air, to product formation, characterized in that the apparatus is equipped, after the feeding device (1) in the direction of motion of the conveying surface (2), with a second endless conveying surface (4a) provided with gripping means, such as pins or the like, the second conveying sur¬ face (4a) forming together with the first conveying surface (2) a pas¬ sage (5a) between the opposing conveying surfaces for separating and mixing the particles.

2. An apparatus according to claim 1 , characterized in that after the passage (5a) in the direction of motion of the second convey¬ ing surface (4a) there is a point (C) where the second conveying sur¬ face (4a) is situated in a tangential relation to the medium flow (S) in the channel (3) for delivering particles to the flow.

3. An apparatus according to claim 2, characterized in that both on the first conveying surface (2) and on the second conveying surface (4a) after the passage (5a) in the direction of motion there is a point where the surface is in direct contact with the channel (3) for re- leasing particles both from the first conveying surface (2) and from the second conveying surface (4a) to the same flow (S) running in the longi¬ tudinal direction in the channel.

4. An apparatus according to claim 1 , 2 or 3, characterized in that the direction of motion of the second conveying surface (4a) in the passage (5a) is arranged parallel to the first conveying surface (2).

5. An apparatus according to any of the preceding claims, characterized in that the apparatus comprises a circulation path be¬ ginning from the passage (5a) between the first and second conveying surfaces (2, 4a), intended for particles not separated from each other, and ending on the first conveying surface (2), in a region between the feeding device (1) and the passage (5a).

6. An apparatus according to claim 5, characterized in that at least the beginning of the circulation path consists of the second conveying surface (4a) after the passage (5a).

7. An apparatus according to claim 6, characterized in that after the beginning consisting of the second conveying surface (4a), the circulation path is continued by a third endless conveying surface (4b) which is provided with gripping means, such as pins or the like, and forms a passage (8) with the opposing second conveying surface (4a), wherein the passage (8) has a transfer point (D) for transferring parti¬ cles onto the third conveying surface (4b), wherein the third conveying surface (4b), in the direction of its motion after said transfer point (D), forms a passage (5b) together with the opposing first conveying sur¬ face (2) for returning particles onto the first conveying surface (2).

8. An apparatus according to claim 7, characterized in that the directions of motion of the second and third conveying surfaces (4a, 4b) in the passage (8) between them are arranged to be opposite.

9. An apparatus according to claim 7 or 8, characterized in that in the direction of motion of the first conveying surface (2) before the passage (5b) formed by the third conveying surface (4b), there is a passage (5c) formed between the first conveying surface (2) and a conveying surface (4c) carrying out the pre-releasing of particles and provided with gripping means, such as pins or the like.

10. An apparatus according to claim 9, characterized in that the directions of motion of the conveying surface (4c) conducting the pre-releasing and the first conveying surface (2) in the passage (5c) between them are arranged to be parallel.

11. An apparatus according to any of the preceding claims 5 to 10, characterized in that the first conveying surface (2) is provided

^" with a circulation path for returning particles not transferred to the me¬ dium flow (S) to the feeding point (A) of the feeding device (1).

12. An apparatus according to claim 4, characterized in that the gripping means of the first conveying surface (2) point in the direc¬ tion of motion of the surface and the gripping means of the second con¬ veying surface (4a) point opposite to the direction of motion of the sur- face.

13. An apparatus according to claim 8, characterized in that the gripping means of the second conveying surface (4a) point opposite to the direction of motion of the surface and the gripping means of the third conveying surface (4b) point in the direction of motion of the sur¬ face.

14. An apparatus according to claim 10, characterized in that the gripping means of the first conveying surface (2) point the direction of the surface and the gripping means of the conveying surface (4c) conducting the pre-releasing point opposite to the direction of motion of the surface.

15. An apparatus according to any of the claims 1 to 14, char- acterized in that the endless conveying surfaces consist of peripheral surfaces of cylinders arranged to rotate.

16. An apparatus according to claim 15, characterized in that the first conveying surface (2) consists of the surface of a feeding drum (12), and the other conveying surfaces consist of surfaces of rolls (13, 14, 15) having smaller diameters, one or more of these rolls being disposed one after the other along the periphery of the feeding drum (12).

17. An apparatus according to claim 16, characterized in that the succeeding rolls (13, 14, 15) are arranged to rotate in the same di¬ rection of rotation.

18. An apparatus according to claim 16 or 17, characterized in that the location of the rolls (13, 14, 15) in relation to each other is ar-

^' ranged to be variable in the direction of rotation of the feeding drum (12).

19. An apparatus according to claim 11 and any of the preced¬ ing claims 15 to 18, characterized in that a returning conveyor (6) for particle-like material is provided after the channel (3) in the direction of rotation of the cylinder comprising the first conveying surface (2), the first end of the returning conveyor (6) being in transfer connection with the peripheral surface of the cylinder and the second end being in transfer connection with the feeding device (1).

20. An apparatus according to any of the preceding claims 16 to 18, characterized in that the feeding device (1) and at least one of the rolls (13, 14, 15) are coupled to the same driving motor (M2).