Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a device for moistening a running web.
2. Description of the Prior Art
In paper manufacturing, spinning manufacturing, plastic manufacturing, photographic film manufacturing and the like, various moistening devices are employed for moistening the running web for the purpose of removing the internal stress of the web and controlling the contained moisture. For instance, water sprayers, steam dampening devices, electrostatic moistening devices, air conditioners, and the like, are generally known. But the conventional moistening devices, as examplified above, have disadvantages as follows: moisture will be applied non-uniformly onto the running web, the quantity of moisture can not be finely controlled at will, a large space is required to accommodate the whole device, because of the complex structure and large size thereof, the resultant cost is high, and it is difficult for such devices to be operated both independently and adapted for webs running at high speed.
SUMMARY OF THE INVENTION
This invention provides a web moistening device for uniformly applying moisture to the running web. The moistening device of this invention comprises a casing with an opening facing a running web, a vapor pipe with a jet nozzle disposed in the casing directs vapor towards the same, and a pair of cylindrical rollers for moistening the running web are disposed on opposite sides of the nozzle. The cylindrical rollers are so disposed as to allow fluid to pass through the same in contact with the internal surface and thus cause condensation of the vapor issuing from the jet nozzle and to thereby insure moistening of the web in contact with the outer periphery of the roller upon which condensation occurs.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of an embodiment of the web moistening device in accordance with the present invention;
FIG. 2 is a detailed side elevational view of the main portions thereof in cross section;
FIG. 3 is a sectional view of one of the cylindrical rollers used for moistening purposes in the device illustrated in FIGS. 1 and 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings showing the construction of an embodiment of this invention, a pair of hollow cylindrical rollers 1 and 2 are provided, the outer surface of which is mirror finished with hard chrome plate. Shafts 3 and 4 for respective rollers are relatively small diameter and as best seen in FIG. 3, have enlarged diameter portions 50, and 51, respectively, which define gaps indicated at 7 and 8 between the shafts and the cylindrical rollers themselves which are in the form of shells whose ends are supported for rotation on shafts 3 and 4 by side plates 54 and 55 respectively, these plates defining in conjunction with the shell and the shaft in large diameter portions, axial, cylindrical fluid passages 7 and 8, respectively. The cylindrical rollers 1 and 2 are longitudinally spaced in the running direction of the web 9 and in contact therewith, and a vapor pipe assembly 11 with a nozzle 10 is disposed between the cylindrical rollers. Further, shafts 3 and 4 are provided with radially extending passages 42, 43, 44, 45, for shaft 3, for instance, and radially extending passages 46, 47, 48, 49, for shaft 4. These radial passages guide fluid flow into the cylindrical fluid passages 7 and 8 between the outer shell 52 and 53, respectively, and the inner shafts 3 and 4 upon which they revolve. The shafts are hollow and are provided with axial passages 41, for shafts 3 and 4, to permit passage of fluid to the inside of shells 52 and 53, respectively.
The vapor pipe assembly 11 is in the form of a double pipe arrangement constituting an outer tube 13 terminating in nozzle 10 with a nozzle opening 17 directed upward, that is, it faces the overlying web 9, the outer tube 13 carrying an inner tube 12. The inner tube 12 is connected to the vapor inlet pipe 14. A slit 15 is provided and runs longitudinally within a lower end of inner tube 12, with a larger width slit 19 provided along the lower end of outer tube 13 and in line with the slit 15 of inner tube 12. The gutter 20 is disposed beneath the slit 19 of the outer tube 13. The gutter 20 is inclined and connected to a pipe 21 which receives and removes waste fluid. The reference character 18 indicates a guide passage which extends between the inner and outer tube to the top end opening 16 of outer tube 13, that is, the entry into the nozzle 10, between the inner tube 12 and the outer tube 13. The casing 23 contains rollers 1 and 2 and vapor pipe assembly 11 along with the nozzle 10, with the casing being covered with heat insulating material 22 to form or define a steam chamber 24. At the opposite sides of the vapor pipe assembly 11, there are provided a pair of inclined gutters 27 and 28 which are further connected to waste tube 25 and 26, respectively. A motor 29 drives pulley 31 through a belt 30 to rotate roller 1, and this motion is further transmitted to a pulley 32' from the pulley 32 via a belt 33 to effect rotation of the other roller 2. The reference character 34 denotes a fluid inlet pipe, and numerals 35, 36, 38 and 39 denote rotary joints. A flexible hose 37 connects the rotary joint 36 to the rotary joint 38. The reference character 40 designates a fluid outlet pipe. In operation of the device constructed as described above, saturated vapor whose flow rate is controlled, is directed to the inner tube through vapor pipe assembly 11, and uniform pressure distribution is provided laterally therein. The saturated vapor spouts from the lower opening 15 of the inner tube 12 and is directed upward and onto the web 9 through the top opening 16 entering the nozzle 10 and thence out through nozzle opening 17. A part of the vapor directly immediately impinges onto the running web between rollers 1 and 2, but the residual vapor being at relatively high pressure is shut in a steam chamber 24, since the web contacts the rollers and the casing 22 terminates just beneath the moving web and the small slits between the web and the casing at each end are filled with a vapor with a higher pressure than that of the air surrounding the casing, so there is always a small amount of vapor leaving the sides of the casing which, as stated previously, is at a slightly higher pressure than that of the atmosphere. Thus, while chamber 24 is not completely shut off due to the small gap at the ends of the rollers, it is said to be a closed chamber as defined principally by the running web. Fluid flow enters fluid inlet pipe 34 and exits at 40 while passing through a confined path as defined in FIG. 3, for instance, through axial passage 41 and radial passages 42, 43, 44 and 45, the cylindrical chamber 7 and thence through rotary joints 36 and 38 and flexible hose 37 in a reverse direction through the second hollow roller 2. By controlling the temperature and flow rate of the fluid, the quantity of fluid impinging on the surface of the mirror finish hard chrome plate of rollers 1 and 2 by condensation can thus be controlled. Since the rollers 1 and 2 carrying the condensed vapor are rotated, the moisture accumulating on the same may be uniformly applied onto the surface of the web for uniform moistening of the same. By varying the rotational speed of a continuous variable speed motor 29, the rotational speed of the rollers 1 and 2 can be varied and thus the quantity of applied moisture onto the running web 9 can be readily controlled. A part of the vapor not condensing onto the surface of rollers 1 and 2 is maintained within steam chamber 24 but is a very small amount relative to the amount being applied to the web by condensation onto the surfaces of rollers 1 and 2. On the other hand, any drain fluid out of the lower end of opening 15 of inner tube 2 accompanying the vapor is collected in gutter 20 through the lower end opening 19 of the outer tube and discharged by means of piping 21. The drain fluid at the steam chamber 24 is collected into gutters 27 and 28 provided on opposite sides of the vapor pipe assembly 11 for discharge through tubes 25 and 26.
In accordance with the present invention, vapor for applying an adequate amount of liquid to the running web 9 is used most effectively. The amount of applied fluid contacting the running web to moisten the same can be controlled by controlling the amount of fluid condensed on the surfaces of rollers 1 and 2 by varying the quantity of vapor passing through the nozzle, the flow rate of fluid through the rollers 1 and 2, the temperature of this fluid and thus the temperature of the rollers, the rotational speed of the rollers 1 and 2 as may be readily appreciated. Moreover, it is possible to adequately moisten a web running at high speed with ease by means of the apparatus of the present invention.
The casing is made of such a metal as stainless steel, or other steel, and the thickness of the casing may readily vary. The insulation 22 protects the transfer of heat from the casing and may be formed of glass, wool, polymer, etc.
Though the invention has been described only in accordance with the case where the web runs horizontally, the invention may be adapted to any web state such as one in which the web is at an angle or is, in fact, vertical. By varying the rotational speed of the rollers and by simple combination of several rollers and a vapor pipe assembly including a nozzle, an optimum moistening condition may be easily obtained for any shape of web or a web running at any speed. Thus, the web moistening device in accordance with the present invention has extremely broad application and is simple in construction. Since the construction is simple and occupies a small space, it is inexpensive but very effective to manufacture the same.