JPH0322281B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for dry forming webs, such as nonwovens, of particulate or fibrous materials, and in particular comprises a dispensing apparatus for dispensing these materials onto a perforated conveyor. The present invention relates to an apparatus for dry forming a web. A device of this kind is known from U.S. Pat. No. 4,157,724, in which the dispensing device has a dispensing container which is formed with a wall of a classification screen on the underside and is open at the top, the screen being arranged inside the container. The fibrous material can be gradually exited through these walls, and the material exiting the container is then dropped onto the forming web or conveyor by means of a downward air flow produced by a suction device on the underside of the conveyor. . An impeller is mounted inside the distribution vessel and is adapted to generate a recirculating flow that flows in one direction along one side of the vessel and in the other direction along the other side. These impeller blades also generate an outward motion component from the inside of the screen wall, which forces the material outwardly through the screen, achieving a high distribution capability of the effluent material through the screen wall. Ru.

Although the above-described devices with an impeller can distribute the material uniformly, there is a problem with the power required to drive the impeller. In other words, this impeller simultaneously performs the functions of recirculating the air containing the material and sending the material to the outside of the screen, and it is difficult to change these two functions independently. be. Therefore, it has the disadvantage that the range of changes in its design is extremely limited.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the aforementioned drawbacks and to provide an apparatus for dry forming webs in which both the function of generating a recirculating flow and the function of discharging material out of the screen can be designed independently. It is to be.

An apparatus for dry forming a web of particulate or fibrous material according to the invention comprises a perforated conveyor and an outlet formed across the conveyor and above the conveyor. a dispensing device and a suction device for sucking air downwardly through the conveyor to convey particles or fibrous material from an outlet of the dispensing device toward the conveyor, the dispensing device having an inlet for the particles or fibrous material; and,
a flow forming device for recirculating the flow of particulate or fibrous material in a passage extending across the conveyor within the distribution device between said inlet and said outlet; formed at least in part by a pipe for guiding the flow, the pipe being formed at least in part by the wall of a perforated outlet screen, and further comprising a pipe for guiding the flow through the outlet screen; and a device for directing the flow outwards, so that the generation of the recirculation flow through the pipe and the delivery of the material to the outside of the screen can be designed separately.

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

The device shown in FIGS. 1 to 3 has a perforated conveyor 2 which runs continuously along a closed path (not fully shown) passing under the dispensing device 4. It's starting to move. A suction box 6 is mounted below the device and the conveyor 2 and has an exhaust pipe 8 connected to a suitable suction blower. The distribution device 4 has an outer housing 10 which opens downwardly towards the conveyor 2 and has two pipes 12 extending through the housing across the conveyor, these pipes 12 being used for sorting. Made of screen material, i.e. mesh or perforated plate material. The ends of the pipe 12 are supported by rotary bearings 16 mounted in both end walls 14 of the housing 10, and are connected to each other via U-shaped pipes 18, 20 outside the end walls 14. This U-shaped pipe 20 has a tangential inlet pipe 22 projecting in line with one of the pipes 12. The end of the pipe 12 has an imperforate sleeve 24 cooperating with the bearing 16 and is sealed and rotatably supported in or by the ends of the U-shaped pipes 18,20.

Sleeve 24 near at least one end of pipe 12
in cooperation with a drive device, for example, as shown in FIG. 1, the pipe 12 and sleeve 24 are rotated by a drive belt 26 driven by a motor pulley 28.

A groove-shaped opening 30 is provided on the upper side of the housing 10, the width of which is adjusted by a valve plate 32.

The above-described apparatus is such that the air fluidized fibrous material is passed through a tangential inlet pipe 22 from a blower (not shown).
is supplied through the pipes 12, 18,
20 is operative to create a recirculating material flow within 20.
From this flow, the individual fibrous materials are transferred to the inlet pipe 2
together with a portion of the transport air supplied via 2 exits through the wall of the exit screen. Air is supplied by the suction box 6 to the groove-shaped opening 30 in the housing 10.
It is sucked in through a perforated conveyor 2. This nearly vertical air flow travels across the pipes of both screens and out of them, contributing to the action of delivering the fiber material from the pipes and carrying the outwardly directed material to be deposited on conveyor 2. .

The air drawn downwardly through the upper channel openings 30 has the additional effect that this serves to clean the outside of the screen pipes as well as their holes in turn as the screen pipes rotate, and the air below the pipes. In the vicinity of the outlet hole, the fiber material adhering to the inside of the pipe is swept away downwards. The clumps of fibers that have collected on the outside of the pipe are blown away when they come upwards due to the rotation of the pipe. Therefore, it is possible to prevent the growth of lumps that may occur on the outside of the classification screen due to static electricity, etc., thereby eliminating disadvantages such as such lumps growing large and falling onto the web on the conveyor. removed.

Cleaning of the holes and the outside of the pipe 12 of the screen is accomplished by rotating brushes or by a nozzle device 44 provided in the pipe 46 connected to compressed air as shown in FIG.
This is accomplished even more effectively by continuously or intermittently blowing a jet of air onto the outside of the pipe 12, such as by an additional outside cleaning device. A very effective cleaning is achieved in this way, so that considerable lengths of fibers can be treated more reliably.

In large manufacturing facilities, simply recirculating the material by air supplied through the inlet pipe 22 is insufficient to ensure proper air fluidization and retention of the material. Therefore, each pipe 1
A stirring cylinder 34 is provided axially disposed within 2 to direct the flow of material to the outside of the pipe, this cylinder 34 being provided with a radial stirring needle 36 along its entire length and bearing 4
A pulley 42 having shafts 38 mounted in the cylinder 34 with at least one end thereof extending outwardly and capable of turning the cylinder 34 relatively quickly by a suitable drive (not shown). or a similar device is provided.

The outer diameter of the combination of the needle 36 and the stirring cylinder 34 is smaller than the inner diameter of the pipe 12;
is preferably mounted eccentrically so that the needle 36 can access and clean the lower inside of the pipe 12 of the screen. This allows the tip of the needle 36 to clean out any fiber clumps that may occur on the inside of the pipe, and also to break up any clumps of material if the material contains fibrous clumps.

Furthermore, this needle 36 serves to throw the material directly outward through the screen and has an extremely high delivery capacity.

As shown in FIG. 3, the needle 36 is mounted on the cylinder 34 at a small distance along the thread line on its surface, and when it rotates quickly, the needle 36 acts like a conveyor worm and moves the pipe 12. It strengthens the flow of material through. The recirculation flow is an ordinary blower device,
For example, it can also be made with an axial blower mounted directly near the end of the cylinder. Another method is to inject transport air into the device through nozzles placed inside the U-shaped pipes 18 and/or 20. However, it appears that the use of stirring cylinder 34 may be sufficient to accomplish this purpose if needle 36 is placed along the thread line.
Of course, the production of recirculating flow can be further increased by making some of the needles 36 slightly propeller-shaped.

Inside the pipe 12, near its upper side, a shielding plate 48 can be provided whose ends are secured by brackets (not shown) inside the U-shaped pipes 18,20. This shield plate 48 serves to restrict the flow of air through the pipe 12 to the conveyor 2 when it is desired to increase the flow of air down the outside of the pipe 12 of the screen. In this case, air from above can still enter the pipe 12 through the inside sides of the screen.

The needle 36 and the cylinder 35, due to their eccentric position within the pipe 12, have a remarkable effect on breaking up the fibrous mass, and in extreme cases, the material can be removed from the U-shaped pipe without leaving the fibrous mass. It can also be supplied by putting it into the inner opening of 18 or 20. Therefore, the inlet pipe 22 can be omitted or used only for supplying extra air.

In FIG. 4, one or more pipes 50 replace the needles and cylinders in the pipes 12 of the screen.
This shows that it is possible to use . The pipe 50 is connected to a source of compressed air and has a nozzle 52 for discharging a jet of air onto the interior surface of the screen pipe for delivery and agitation of the fibrous material. In this case, the jet preferably has a velocity component in the downstream direction within the pipe.

The flow and pressure conditions within the pipe 12 vary somewhat along its length, and these can be controlled if necessary by placing an axially sloped top shield 48 along the pipe or of varying width. can make some difference in the state of the cylinder 3
The thread line of the needle 36 along line 4 may not have a constant pitch. Alternatively, the size of the holes in the screen can be gradually changed.

It is possible to provide an exit screen on only one pipe 12 and leave the other pipes imperforate, but the movement of the material inside the pipe tends to change the delivery capacity along the length of the pipe, resulting in To ensure a uniform distribution of fibers within the ivy web, the screen pipes are used in pairs so that the return flow through the other pipe compensates for the uneven capacity of one pipe. You can also do that. Conversely, the recirculation device may have more than two screen pipes 12, for example four such pipes.

The rotation of the screen pipes, which is important for the cleaning of the screen pores, should be at such a speed that the centrifugal force created thereby increases the effectiveness of ejecting fibers placed in or near the pores. good.

[Brief explanation of the drawing]

1 is a perspective view of an apparatus for dry forming a web according to the present invention; FIG. 2 is a sectional view of the apparatus shown in FIG. 1; and FIG. 3 is a partial view of the apparatus shown in FIG. FIG. 4 is a cross-sectional view showing another embodiment. 2...Conveyor, 4...Distribution device, 6...Suction box, 10...Housing, 12...Pipe, 1
8, 20...pipe, 34...stirring cylinder, 3
6...needle.

Claims (1)

Claims: 1. An apparatus for dry forming a web of particles or fibrous material, comprising a perforated conveyor and an outlet formed across the conveyor and towards the conveyor. a dispensing device disposed above and a suction device for sucking air downwardly through said conveyor to convey said particles or fibrous material from an outlet of said dispensing device towards said conveyor; The device includes an inlet for the particles or fibrous material and recirculating the flow of the particles or fibrous material in a passageway extending across the conveyor within the distribution device between the inlet and the outlet. a flow-forming device for guiding the flow, the flow-forming device being formed at least in part by a pipe for guiding the flow, the pipe at least in part having a perforated outlet screen wall; is formed,
A device for dry forming a web, further comprising a device for directing the flow of particles or fibrous material outward through the exit screen. 2. An apparatus for dry forming a web according to claim 1, characterized in that the pipe is made entirely of classified screen material and is arranged to rotate. equipment. 3. In the device for dry forming a web according to claim 1 or 2, the device for directing the flow of particles or fibrous material outwards is provided within the pipe 12. Apparatus for dry forming a web, the apparatus being adapted to perform at least one of agitating, disintegrating and axially transporting the material. 4. An apparatus for dry forming a web as claimed in claim 3, wherein the device for directing the flow of particles or fibers outwardly includes a rotating needle having a needle mounted eccentrically within the pipe. An apparatus for dry forming a web, characterized in that it is a cylinder. 5. An apparatus for dry forming a web according to claim 4, wherein the needle is arranged along a thread line of the needle cylinder. . 6. An apparatus for dry forming a web as claimed in claim 5, wherein the device for directing the flow of particles or fibers outwardly is connected to a source of compressed air and mounted on a fixed pipe so that the screen An apparatus for dry forming a web, characterized in that it is an air nozzle that blows an air jet from inside toward the inner surface of a pipe. 7. An apparatus for dry forming a web material according to claim 6, characterized in that a shielding plate device is fixed near the top of the inside of the pipe of the screen. 8. Apparatus for the dry forming of webs of particles or fibrous material, comprising a perforated conveyor and an outlet formed across and towards the conveyor above the conveyor; a dispensing device and a suction device for sucking air downwardly through the conveyor to convey the particles or fibrous material from an outlet of the dispensing device toward the conveyor, the dispensing device comprising an inlet for fibrous material and a flow forming device for recirculating the flow of particles or fibrous material in a passage extending across the conveyor within the distribution device between the inlet and the outlet; and wherein at least a portion of the flow forming device is formed by a pipe for guiding the flow, at least a portion of the pipe is formed by a wall of a perforated outlet screen, and , a device for directing a flow of particles or fibrous material outwardly through the exit screen, and further comprising a device for directing a flow of particles or fibrous material outwardly through the exit screen. Apparatus for dry forming a web, wherein the pipe is rotatably arranged and has a substantially fixed screen cleaning device for cleaning the outlet screen from outside the pipe.