FI112812B - Procedure for foaming and a plant used in the process - Google Patents

Description

112812

Method used in foaming and process equipment Förfarande vid skumarkformning och en i förfarandet använd anläggning 5

The invention relates to a process for foaming and to the apparatus used in the process.

A foam web forming method for forming a web is known in the art.

10 For example, the Finnish Paper Engineers' Association textbook and manual, 'Part III', on page 604, mentions foam printing.

The foam web comprises a large amount of entrained air in the form of bubbles which tend to disassemble and shatter upon exposure of the foam web to an outside airspace of varying pressure. To prevent this, it is proposed in the application of the invention that the foam screening mass be made to flow specifically to the kitformer and to the kit K between the kitformer forming wire H1 and H2. a connection between the headbox and the kitformer, in which the headbox is provided with: • 20 separate guide nozzles on the outboard side of the lip chamber 15, whereby the guide nozzles,. The guide nozzles may preferably be in contact with one another. '. at one end to the associated forming wire Hi or H2 and at one end to the leading edge of the headbox lip chamber. Preferably, the control nozzles i '*'; 25 may be made of an artificial material such as plastic or ceramic.

1 ·

The process of the invention in foam stripping is characterized in that, in the 1L process, the foam stripping mass is passed from the headbox between the forming wires to prevent the expansion of air bubbles in the foam stripping mass by placing the end of the headbox lip chamber against the forming wires.

2 112812

The apparatus according to the invention in foam stripping is characterized in that the apparatus between the headbox and the kitformer is closed so that there are guide nozzles between the front edge of the headbox mouthpiece and the kitformer forming wires to close the gap between the does not come into contact with the outside airspace of the headbox and the associated pressure, thereby preventing the air / gas bubbles in the foam web from being disintegrated and the consequent adverse effect on web formation.

10

The invention will now be described with reference to the figures shown in the accompanying drawings, the embodiments of which are not to be construed as solely limiting the invention.

Figure 1 is a side elevational view and partially illustrative of the headbox used in the method of the invention and the associated kitformer.

Figure 2 illustrates headbox control nozzles for preventing foam stripping from contacting outside air 20.

Fig. 1 shows a headbox according to the invention and a method in which. . the pulp used for foaming, comprising 50 to 70% by volume of air and / or gases, is led from the headbox 10 such that the headbox 10 comprises; 25 manifold 11, piping 12, intermediate chamber 13, turbulence generator 14 and: mouth chamber 15 and then control nozzles 16ai, 16a2. Air and / or gases in the mass are m bubbles. Thus, the foam web mass m is led from the headbox 10 manifolds 11 by arrow Li as shown through the headbox strut 12 to the intermediate chamber 13 and the intermediate chamber 13 to the turbulence generator 14 and the turbulence generator 14 to the lumen chamber 15 and further on the K between the Hi and H2 of the forming wire F forming wire F

The guide nozzles 16ai, 16a2 extend to the gap K between the pivoting rollers 18ai and 18a2 5 of the dieformer 17 The guide nozzles 16ai and 16a2 extend to the forming wires H1 and H2. The headbox 10 thus comprises a lip-chamber structure 15, 16ai, 16a2 which prevents the foam printing mass m from contacting the outside airspace. Thus, in accordance with the invention, the foam web m is thus fed in a closed state directly from the headbox to the gap K between the forming wires H1 and H2 and further through the dewatering units 19ai, 19a2, 19a3 between the forming wires H1 and H2.

Dewatering is performed uniformly on both sides of the run of the forming wires H1 and H2 by dewatering units 19ai, 19a2, 19a3. The foam web mass m is thus guided from the manifold supports of the headbox 10 through the lip chamber to the gap between the wires Hi and H2 and further between the wires Hi and H2 as the forming wires Hi and H2 pass through the rollers 18ai and 18a2. The internal pressure of the dewatering units 19ai and 19a2 is lower than the pressure of the mass web m between the wires H1 and H2.

• '* 20 By adjusting the difference between the internal pressure of the dewatering unit and the pressure of the pulp track, * * _', the dewatering and the structure of the paper formed can be adjusted. The dewatering units 19ai, 19a2 and 19a3 shown in the figure comprise lists ci, C2, C3 ...; di, d2, d3 ... and no, e2, e3 ... The dewatering unit 19a3 lists no, β2, e3 ... are more densely spaced than the preceding dewatering unit 19a2 lists di, d2 ... The mass path m passes. . 25 between the forming wires H 1 and H 2 and in the figure as shown by arrows Si; m foam strip m water on both sides. The dewatering units 19ai, 19a2 and 19a3 may also be subdivided into a plurality of chambers, each of which may be individually adjusted to optimize dewatering and paper structure.

Thus, in the process of the invention, the foam web mass m is not allowed to come into contact with the outside air when flowing out of the headbox 10, whereby air bubbles in the stock tend to burst and release from the stock which is a problem with foam printing.

5

Figure 2 illustrates the use of extruder portions 16ai, 16a2 to prevent the foam web m from coming into contact with the outside airspace. The nozzle parts, i.e. the guide nozzles 16ai, 16a2, are preferably made of ceramic or plastic material and are preferably attached by screws R to the headbox structure. 10 Other mounting methods are also possible.

• I »► s t * * II» »'»

Claims (4)

A foam molding method, wherein a foam molding mass (m) is caused to flow Iran a distribution boom (11) into an inlet carriage (10) through a pipe system (s) (12 and 14) which causes turbulence in the mass flow further to a lip chamber (15). ) and by which process such foam forming mass (m) is caused to flow comprising 50-70% by volume of air and / or gases and in which method foam forming mass is brought into a gap (K) between forming wires (Hi and H2) in a gap former. in the immediate vicinity of rollers (18ai, 18a2) which control the forming wires (Hi and H2) and in which method dewatering units (19ai, 19a2, 19a3) have been arranged on both sides of that of the forming wires (Hi and H2) and the one between these transporters. -ported foam web mass (m) formed the race, whereby the Iran mass web (m) removed the water on both sides thereof by means of the units (19ai, 19a2, 19a3), the forming viruses (Hi, H2) having ts along lists (c1, C2 ...; di, d2 ...; ei, e2 ...) in the dewatering units (19ai, 19a2, 19a3), characterized in that air bubbles in the foam web mass (m) are prevented from expanding in the process when the web molding mass (m) is led into the inlet carriage (H1). and H2) by placing the end of the lip chamber (15) in the inlet carriage (10); Connection to the forming viruses (Hi and H2). » 2. A method according to claim 1, characterized in that in the method, nozzle portions (16ai, 16a2) which are connected to the orifice of the lip chamber (15) are turned into the inlet carriage and by means of which the web forming mass (m) is poured at the same pressure as in the lip chamber (15) and access to the outer the foam space mass (m) is prevented by closing the free space between the leading edge of the lip chamber (15) in the inlet carriage (10) and the forming wire (Hi; H2) with a guide nozzle (16ai, 16a2). 30 Method according to claim 1 or 2, characterized in that the internal pressure in the dewatering units (19ai, 19a2, 19a3) is lower than the pressure of the pulp web (m) s 112812 between the wires (Hi and H2). A foam web forming plant comprising a distribution boom (11) in an inlet drawer in a paper machine and after the distribution stock a 5 or more pipe systems (12, 14) sort of cause turbulence in the mass flow and further after the pipe system (s) a lip chamber (15). ), which taper in the direction of its outlet end and which plant solution comprises after the inlet carriage (10) a gap former (F) comprising forming wires (Hi and H2), whereby a foam forming mass (m) is flowed into a gap (K) flour. Between these from the inlet carriage (10) and wherein on both sides of the passage between the forming wires (Hi and H2) in the former (F) are provided dewatering units (19ai, 19a2, 19a3), which remove the water from the foam web mass (m) between forming wires (Hi and H2) and which comprise moldings (ci, C2 ...; ei, β2 - ..; di, d2 ...) which start in contact with the forming wire (Hi or H2) and that the web forming mass (m ) brought to flow from the distribution boom (11) comprises 50 to 70% by volume of air and / or gases, characterized in that the plant is closed between the inlet carriage (10) and the gap former (F) in such a way that between the leading edge of the lip chamber (15) in the inlet carriage (10) ) and the forming wires (Hi and H2) in the gap former are provided control nozzles (16ai, 16a2), which seal the space between the inlet carriage (10) and the gap former, the foam forming mass (m) being led from the distribution bar (11) in the inlet carriage ( 10) into the gap (K) between the forming wires (Hi and H2) in the gap former (F), does not enter! contact with the air space outside the inlet carriage and the pressure associated therewith, thereby preventing rupture of the air / gas bubbles present in the foam forming mass (m) and the consequent detrimental effect on the web formation.