DE2116042A1 - Method and apparatus for removing powder from the atmosphere - Google Patents

Description

ΟΧΪ-DRY INTERNATIONAL LIMITED Shannon, Ireland

Method and apparatus for removing powder from the atmosphere,

The invention relates to a method and an apparatus for removing airborne suspended powder from the atmosphere and relates in particular to a device used in conjunction with the application of powder to a moving surface following the powder application to remove the in the air floating powder is used.

It is very desirable or necessary in many industrial situations to add powder material to a to apply moving surface. As a representative example of the printing industry can refer to the usual Application of powder, e.g. starch, to a moving (generally electrostatic means). low paper web or printed sheet to prevent

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the Fsrsehmierens of printing ink are referred · Although the powder application effectively prevents smearing, not all of the powder adheres to the Migratory, d®n surface · A substantial amount remains in the Ijiift float and possibly accumulates on the equipment, the walls, The ceiling or the floor of the pressure room and is reflected on the people present in this area.

As far as a press for printed sheets is considered, separate gripper bars convey individual sheets, and there is a gap between the end of one sheet and the leading edge of the next sheet · This causes intermittent pulsations of the powder, causing the powder to float in the air stay, reinforced. This excess powder is commonly referred to as "fly around" »

At Druckpress'Sa fib? Paper webs can cause other problems from 3? © -y © B _o So the powder application are generally set up _{to dispense 5} tas of pulper via © ia © n gageböiii in the Abstaad · Vfein “but are you paper 3? baim won ger-iager-sz ⁵ Brsit © as this given distance is loaded with PuXv @ r 3'S? -j © rden sraB ₉ so not only the excess © generated by the bsw © r --v.ds paper web is created Ptil ", -!" ■ ii hold the air

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BATH ORIGINAL

is turned to close to the outside and then remove the powder from the vicinity of the printed sheet by means of negative pressure. These solutions have proven to be very costly and have impaired the quality of the powder application itself. Furthermore, the installation is sometimes difficult because of the space available in the press been*

Accordingly, it is a primary object of the present invention to provide a method and apparatus for removal of the excess airborne powder from a moving surface following to create the powder application on this surface, which is economical and which a considerable part " of the excess powder without significant impairment of the desired powder application on the mentioned Surface removed. Another object of the invention is to provide a device that sufficiently is compact so that it can be easily installed on most of the common printing presses.

The invention relates to EIA method or device for removal of excess, floating in the air powder after the application of the powder on a moving surface, such as a paper web or a sheet, for which purpose a manifold downstream passageway i Windwärts provided by the powder application site to to capture the powder floating in the air and to discharge the collected powder through the combined effect of a fluid flow, by means of which the powder is moved towards the ends of the collecting line, and the maintenance of a slight negative pressure in the area of the ends of the collecting line, e.g. into a suction trap

Other features and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which point

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Fig. 1 is a perspective view of an embodiment of the device according to the invention, showing the arrangement of the device in relation to the powder application device represents, with a portion of the manifold shown partially broken away to a To illustrate air or fluid distributors »

Pig * 2 is a cross-section along line 2-2 of Fig. 1j in more detail shows a housing for reduction of the escape of the collected powder made clear,

Figure 3 is a cross-sectional view taken along line 3-3 of Figure 1 showing the location of the fluid manifolds in relation to the manifold and

Figure 4 is a cross-section along line 4-4 of FIG Figure 3 illustrates the details of the fluid distributors.

Although the invention is amenable to various embodiments and alternative forms, are specific embodiments in the drawing, for example and are described in detail below »It should be noted, however, that it is not intended in this way to extend the invention to the particular embodiments illustrated restrict. On the contrary, all embodiments, equivalents, and alternatives falling within the scope and under the idea of the invention fall, be claimed

FIGS. 1 and 2 show an exemplary embodiment to remove the airborne powder following application of the powder on a moving surface, with the effectiveness

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the powder application itself is not significantly affected will. As shown, the powder 10 is applied to a moving surface 12 by means of a powder spray or Applicator 14 applied. Any conventional spray device can be used. Electrostatic Powder spray devices such as those described in U.S. patents 3.273.016, 3.292.045, 3.292.046, 3.341.740 and 3.344.312 can be advantageous for Application.

In accordance with one feature of the invention, a collection device is provided to capture at least a substantial portion of the airborne powder. As shown, a collection surface or manifold 16 is provided. The manifold 16 can have any desired shape provided that it forms an open collecting housing for the powder. The housing should allow free access and have a restricted exit. It is preferable to use a housing with a collecting surface that is substantially rectangular in shape. * The rectangular housing is open at the bottom near the moving surface for optimum effect. However, an adequate effect can also be achieved if the cross section of the collecting surface has a different geometric shape, ζ · Β · a semicircle, a parabolic surface or the like. In the illustrated embodiment, the manifold 16 has a rectangular collecting surface 18 (see FIG. 3) that is 30 cm (12 inches) wide and 7 »6 cm (3 inches) high. The collecting line 16 should preferably have a length which essentially corresponds to the maximum spray width of the powder application device 14 itself. speaks. Because of the turbulence caused by the high speed of the moving surface, the excess powder particles will settle in the area downstream of

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of the powder applicator focus · The exact location of the manifold 16 depends on the normal Operating speed of the sprayed printed sheet or paper web from · For example, has proven to be useful proved to be the manifold in a printing press for sheets that is operated at normal speeds 16 to be placed approximately 15-20 cm (6-8 inches) downstream from the electrostatic powder applicator.

In order to remove the trapped powder particles from the housing or the collecting surface, according to another feature of the present invention, the action of a fluid such as air is used to direct the powder outwards against the ends of the collecting line 16, in combination with the effect of a slight negative pressure to remove the powder from the areas of the manifold 16 and suck the powder without pulling powder from the sprayed, moving surface. The combination of these forces provides effective powder removal without simultaneous drawing of deposited powder from the moving sheet or paper web.The air pressure or other fluid pressure must be sufficient to move the powder outwardly to the ends of the manifold 16 However, T3 must not be so great that the air flow acts like a (strong) negative pressure and thereby pulls powder off the sprayed surface.In the same way, the negative pressure (at the ends of the manifold 16) must be so low that powder is drawn off to prevent the sprayed surface, but on the other hand are still sufficient to control the movement of the powder to its final collection in a trap outlet, to its distribution in the atmosphere or to the connection to a different exhaust system to ensure · It is therefore ₉ as shown, Air from a source not shown

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an air regulator and filter 20 are printed over lines 22 and 24 through a manifold 26 located in the center of the manifold 16. The distributor piece 26 has openings 28, 28 which direct the air or another fluid to the outside. The distributor piece 26 should advantageously be arranged essentially in the center of the collecting line 16, so that the air pressure drives the particles against the ends of the collecting line 16 with essentially the same force in both directions. It has also been found advantageous to position the manifold 26 close to the collection surface 18 of the manifold 16 such that the openings 28, 28 'direct the air or other fluid against the surface 18. Optimal conditions are achieved when the air flow contacts the collection surface near the collection chambers 30. This can be achieved by arranging the openings 28, 28 'at angles to the horizontal of 1-5 °. In a representative example, in connection with a press for printed sheets, it has been found appropriate that the source of fluid have a gauge pressure of 0.2 - Q _e 7 st »(3 - 10 pounds per square inch) with orifices 28 _x 28 ¹ of about zero , 8 mm (1/32 inch) diameter delivers «

It should be noted that manifold 26 has more than one in each direction of flow May have opening if necessary or desired. If several openings are planned, so they are generally used more, at least initially, to move the air to the sides of the case than directing to the ends of the manifold.

To the powder _v aasameln to emerge from the ends of the bus line 16, plenum chambers 30 are provided, through which the air is sucked

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and which are suitably sized to enclose all suspended powder particles by a slight negative pressure to be removed and collected in a suction trap. The collection chambers 30 form a means for Constriction and further concentration of the powder flow · For this purpose, as shown, suction chambers are provided 30 is provided, the entry surface 32 of which has a cross section which is essentially the width w the collecting line 16 and whose height corresponds to h · As shown, the collecting chambers 30 are with the collecting line 16 connected and form a continuous system · This can be done by conventional fastening means, e.g. through Soldering, can be achieved.

While in this way the escape of powder is reduced, it must be taken into account that satisfactory operation will be achieved even when the manifold and the collection chambers are not connected to one another. The wedge-shaped collection chambers concentrate the powder flow exiting the collection chambers through outlet conduits. These outlet lines can have a circular cross section and a diameter which corresponds to the height of the collecting chamber inlet cross section 32. In this way, the heights and transverse dimensions of the collecting chambers can be varied as desired. Similarly, the collecting chambers 30, which are preferably on the same level as the collecting line 16, can also be arranged higher or lower if this is necessary because of the spatial limitations of the machine to which the invention is applied. The relative height can be varied widely as long as the negative pressure is sufficient to suck the powder flow through the collection chambers. The same considerations apply to the distance between the ends of the manifold

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and the collection chambers. In the case of a press with sheet feed For example, the suction chambers can be arranged just outside the paths of the gripper bars.

In a further development of the present invention, an air curtain can be used in connection with the manifold in order to prevent powder from escaping from the manifold. Thus, as shown in FIG. 1, an air curtain 29 has an air control tube 31 which is arranged near that side of the collecting line 16 facing away from the powder spray device 4-0. From a source (not shown), air is fed to the air regulating tube 31 via an air regulator 33. The air can conveniently escape from the air regulating tube I through a series of spaced openings. It has for example been found to be satisfactory, openings of 0.7 mm (0.03 inch) diameter to be used, at intervals of about 3 _f 8 cm (1 - 1/2 inch) ribbon Abs are arranged. An overpressure

from about 0.14 to 0.48 kg / cm (2-6 pounds per Square inches) is sufficient. It should be noted that sufficient Results aiii-.h without the use of an air curtain been reached. However, in order to achieve optimal E-pgGbniiJwe with the present invention, a ! Air curtain can be provided »

The I'raniipai / b der PuLverbe.Llc; lion from the end ti η dor · mutton line to the coffin chambers un.i possibly in an AbaaugfaLLo becomes b «i einoin ^; ο wrestle UnUm / Druck durchge-!. "i'hr.'t ;. './id dargfüitz-el I i ,, oiv, ougt οLn Gobi-is« j56 eirion oppression, which the Pul ;, brom in die iJanmielkammei-n 50 through bi.egaame lines ^: j <-, a Vorbeiler-l'-Sbtiok 40, a reveal 4r 'in η ir ο suction trap pulls, the' length of the Loifpinyon .-. wiflchen the Luntritb up to the 7oi'teilersbück and joder flammeIkamin. c should be essentially the same, ao that the same pressure ratios are given · unequal

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Pressure could cause some of the powder particles to escape ^. In connection with the system described above can advantageously the conduit has an inner diameter of about 7, 6 cm (3 inches) and the! D-piece can have an outlet on the fan side of about 10 cm. The use of the invention under difficult conditions may require the use of larger diameters for the pipes and the T-piece. The fan may suitably be a power of about 10 before air per minute (550 cubic feet per minute) have.

According to a further embodiment of the present invention, the powder particles can be collected in a suction trap which is air or fluid permeable to allow passage of the air or fluid. For this purpose, the powder is collected in a suction trap 44, which consists of a woven cotton sack which is sufficiently porous to allow the air to escape into the atmosphere. Preferably, the trap should have a capacity sufficient to limit the frequency with which it must be cleaned to remove the collected powder. For example, a case with a capacity of 45 kg (100 pounds) can be used. For optimal operation, the powder should not take up more than 5 - 10 % of the contents of the trap. A trap with a content of 45 kg (100 piunds) · that is used in conjunction with; The deposition of starch on printed doges in a sheet press is used _f should collect 1-15 kg (2-j> 0 pounds) of powder during 120 hours of operation. If desired, the powder bromine can be connected to any existing suction line or blown into the atmosphere.

While the trap collects the major part of the powder, a small part can with the air

BATH ORIGINAL 109843/1253

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. get through the woven pouch. After another Embodiment of the present invention can provide an additional barrier to the escape of powder into the Air can be obtained by placing the trap in a housing with a filtered outlet. So is the housing 46 is provided for accommodating the outlet trap 44. It can be fitted with a removable cover plate 48 and a seal 50. The cover plate 48 can be attached to the top edges of the housing by any suitable means. An airtight joint 52 is provided for the implementation of the line 42. In one side of the housing 46 is in a suitable frame a filter 54 inserted into an outlet opening for the air. ™

It should be noted that the use of a symmetrical system, i.e. a system in which the Fluid distributor 26 is arranged in the middle of the collecting line and with the same line lengths should be preferred because of its simplicity. However, it is within the scope of the invention that to change the corresponding line lengths and the position of the distributor T-piece and to provide a system that Coordinates the relative negative pressure and the flow pressure to ensure the removal of the powder. In other words, the negative pressure can within certain limits (j zen on one side compared to the other (by changing the pipe length) can be reinforced and the manifold tee can be closer to the side of the smaller one Negative pressure are added, with an effective removal of the powder is still achieved.

When a press with paper web feed comes into consideration or in other cases where the moving surface is not as wide as the given distance of the powder applicator, the

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Activation of a second bus and a second Distribution piece can be useful · The collecting line can be below the paper web or the moving one Surface with an upward-facing collection surface can be provided · Additional collection chambers are not necessary·,

The invention thus provides a method and apparatus for removing excess airborne powder subsequent to the application of the powder to the surface of a sheet, paper web or other surfaces which are generally moving at a high speed removal of the powder is achieved _t without the previously deposited powder is affected on the moving surface · Nevertheless, the device is simple and compact ·. formed and can easily be on conventional printing machines or the like. be attached,

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Claims (14)

- 13 claims G) 1 J A method for removing excess airborne powder when applying powder to a moving surface, characterized in that a manifold is arranged in relation to the moving surface and the powder application site such that at least a portion of the airborne Powder is captured, guides the captured powder in the form of a moving powder stream in sighting the ends of the manifold, maintains a moderate negative pressure in the area of the ends of the manifold to maintain the powder movement and sucks the powder off. Ä 2. Device for carrying out the method according to claim 1, characterized by a collecting line (16) which is arranged in relation to the moving surface (12) and the powder application parts that at least part of the powder suspended in the air is captured, a fluid distributor (26) arranged in the manifold for guiding fluid to the ends of the manifold (16), a fluid source for supplying the fluid distributor with fluid, collecting chambers (JO) in the region of the two ends of the manifold (16), means (34) Aufrechterhai to a sufficient negative pressure for the conduction of the powder from the areas of the ends of the bus line (16) to the S i fcung amm elk aminern (JO), and Mibtel (36) for sucking the collected powder. 3. Apparatus according to claim 2, characterized in that the suction device is connected to one with the S'aiamelkammern (30) Contain suction traps (44) for collecting the powder, wherein the trap (44) is sufficiently permeable to a To allow passage of the scrömungaiaibel. 4. Device according to claims 2 - 3> characterized in that an air curtain (29) on the powder feed BAD ORtQINAL 109843/1253 Bring device (14 ·) facing away from the collecting line (16) is provided. 5 · Device according to claim 2-4 ·, characterized in that that the collecting chambers (30) and the collecting line (16) are connected to one another. 6. Apparatus according to claim 2-5 »characterized in that the fluid distributor (26) in the middle Area of the manifold (16) is arranged and that at the ends of the manifold essentially the same negative pressure is maintained. 7. Device according to claim 2-6, characterized in that that air is used as the fluid. 8. Apparatus according to claim 2-7 »characterized in that the collecting line (16) is rectangular Has collecting surface (18), * 9. Apparatus according to claim 2-8, characterized in that the manifold (16) is downstream of the powder application device (14) is arranged. 10. Device according to claim 2-9 »characterized in that that the manifold (16) is substantially equidistant from the moving surface (12) is arranged like the powder application device (14 ·). 11. The device according to claim 2-10. characterized, that a second manifold and a second fluid manifold below the moving Surface (12) are arranged to catch falling powder and it to the collecting chambers (3) conduct. 109843/1253 12. The device according to claim 2-11, characterized in that the connections between the collecting chambers (30) and the suction trap (44) consist of flexible tubes (34) and that the vacuum generating device (36) between the collecting chambers (30) and the suction trap (44) are arranged, the lengths of the tubes (34) being substantially the same. 13 · Device according to claim 2-12, characterized in that a fan (36) is used as the vacuum generating device serves. 14. Apparatus according to claim 2 - 13 »characterized denotes overall i, that a closed housing (46) includes an exhaust trapping unit (44) and comprises in series connection of an opening and a filter (54) through which the collected powder is retained while the flow medium escapes through the opening 109843/1253 L e r s e i t e