Field of Search:
101/349-352,363,364,366,206-210,148 118/258,259,262 401/208
Description:
BACKGROUND OF THE INVENTION
This invention relates to printing apparatus for pile fabric, and more particularly to a device for metering dye to a fabric printing roll.
There are many problems relating to the dyeing of pile fabric, and particularly patterned pile fabric, derived from the inability to control the precise amount of dye delivered to the portion of the fabric to be printed. An insufficient amount of dye can produce too light a color or non-uniformity of color in the printed area, and an insufficient depth of color in the pile surface. Too much dye applied to a printed area can produce too dark a color, and also "wicking" of the dye to adjoining non-printed areas.
The printing of pile fabrics is preformed generally in a manner similar to the printing of other web materials, such as paper, that is, by moving the web of fabric between a printing roll and a back-up or pressure roller. If the material is to be printed in a pattern, the printing roll is covered with radially projecting pattern elements of absorbent or cellular materials which are filled with the dye and compressed by the pressure roller to extrude the dye from the pattern elements upon the fabric.
Various methods are employed to feed or distribute the dye to the absorbent cover material of the printing roll. One method is to rotate the printing roll in a dye reservoir so that the absorbent cover material will absorb the dye while in the reservoir. Another method is to mount a solid squeeze roller in the reservoir to engage and squeeze the air from the absorbent cover material so that the absorbent material will absorb more dye as it expands to its original natural shape. Another method is to mount the print roll, particularly a pattern roll, so that only the absorbent pattern elements will dip into the dye liquor without unnecessarily coating the non-pattern areas of the roll.
All of the above methods have been deficient in uniformly metering dyeing liquor to the printing roll, and particularly to the absorbent elements of a pattern roll.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide, in a pile fabric printing head or printing roll assembly, a device for accurately metering dye liquor to the printing roll, and particularly to the absorbent elements of a pattern roll.
The apparatus made in accordance with this invention includes a conventional pattern printing roll having the cellular or compressible absorbent pattern elements and a back-up or pressure roller for printing the web of pile fabric between the pressure roller and the printing roll. However, the metering device comprises a meter roll mounted for rotation preferably laterally of the printing roll. The surface of the metering roll has a hard surface provided with elongated parallel grooves of uniform size and spacing adapted to engage and compress the absorbent pattern elements of the printing roll. The dye liquor is preferably poured in a uniform stream upon the top of the meter roll to fill the grooves. Thus, each groove contains and distributes a uniform amount of dye liquor at a uniform rate into the cellular pattern elements. Moreover, the hard surface of the meter roll first squeezes the air from the cellular pattern elements which the meter roll engages. As the contiguous portions of the meter roll and printing roll roll away from each other, the expanding cellular pattern elements suck in the metered amounts of dye liquor from the grooves.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary side elevation of a printing apparatus made in accordance with this invention, incorporating two pattern printing heads, the lower one of which is disclosed with parts broken away; and
FIG. 2 is an enlarged fragmentary sectional elevation of the meter roll, made in accordance with this invention, distributing the dye to the pattern printing roll.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings in more detail, FIG. 1 discloses portions of a stationary frame 10 of a printing range incorporating a pair of printing heads 11 and 12 for applying two patterns to a web of tufted pile fabric 14. Since each printing head 11 and 12, made in accordance with this invention, is of identical construction, the parts of each will be referred to by identical reference numerals.
Each printing head 11 and 12 includes a pattern printing roll 15 having a hard base or core 16 made of a material, such as wood. The core 16 is covered with pattern elements, which include a hard rubber base 17 secured to the surface of the core 16, and an absorbent and compressible cellular material 18 fixed to the outer surface of the base 17. The pattern elements 17-18 are, of course, carved out in a surface configuration in accordance with the pattern desired upon the fabric web 14.
The pattern rolls 15 are provided with shafts 20 supported for rotation in journals 21 adjustably mounted by any convenient means upon the frame 10.
Also mounted in journals 22 upon the frame 10 for rotatable movement are the shafts 23 of the hard pressure rollers 34. As disclosed in FIG. 1, the pressure rollers 24 are mounted to force the web 14 into printing engagement with the patterned printing rolls 15. The pressure of the rollers 24 is such that the absorbent pattern elements 18 will be squeezed to extrude the dye liquor contained therein upon the lower face of the web 14, as the web 14 moves in the direction of the arrow of FIG. 1.
Pattern rolls 15 are driven, by any convenient means, not shown, in the direction of the arrow.
Located on the opposite side of the pattern roll 15 from the pressure roller 24 is a meter roll 25. The meter roll 25 is preferably made of a hard material, such as aluminum tubing. The surface of the meter roll 25 is formed into uniformly circumferentially spaced elongated grooves 26 of uniform size which are straight and parallel to the axis of the meter roll 25. The ends of the meter roll 25 are provided with stub shafts 27 journaled in journal brackets 28, slidably mounted in slide frames 29 for adjustment toward varying degrees of engagement of the meter roll 25 with the pattern elements 18.
The meter rolls 25 are driven at a uniform rate in the direction of the arrow disclosed in FIGS. 1 and 2, by any convenient means, not shown.
Located above each meter roll 25 is an elongated reservoir tray 30 supported on a tray frame 31 for tilted adjustment, so that the front wall 32 is lower than the rear wall 33 to provide an overflow for dye liquor 34 introduced into the tray 30 from inlet conduit 35.
The tray 30 is located preferably in such a manner that the front wall 32 is almost directly and vertically above the rotary axis of the meter roll 25. Thus, the tilted tray 30 permits dye liquor 34 to flow over the horizontal top edge of the front wall 32 in a uniform stream down upon the rotating meter roll 25. The grooves 26 then become filled with the dye liquor, and retain uniform amounts of the dye liquor as they approach contact with the pattern elements 18 of the printing roll 15, as best disclosed in FIG. 2.
As the meter roll 25 rotates into engagement with the printing roll 15, the hard exterior surface of the meter roll 25 gradually compresses the cellular material. Then, as the surface of the meter roll 25 moves away from the extreme pads 18 is gradually relaxed, permitting the inherent resilience of the material to expand the pattern elements 18 to their original natural position. The expansion of the cellular pads 18 creates a vacuum which is immediately filled by the metered amount of dye from each groove 26.
Thus, a precisely controlled amount of dye liquor is extruded at a uniform rate from the uniform grooves 26 into the cellular pattern material 18. As the surface of the meter roll 25 disengages the cellular surface of the printing roll 15, the cellular pattern element 18 is completely, but not excessively filled with dye liquor 34. The metered amounts of dye liquor are then carried by the cellular pattern elements 18 to the printing position, where they are extruded against the face of the pile fabric web 14 by the back-up or pressure roller 24. The empty pattern elements 18 then return to be refilled by the grooves 26 of the meter roller 25. In the meantime, the discharged grooves 26 of the meter roller 25 continue rotating until they are refilled by the uniform stream of dye liquor overflowing the front wall 32 of the reservoir tray 30.
Any dripping or excessive dye liquor from either the pattern roll 15 or the meter roll 25 is collected in the drip pans 38 and 39 from which the dye liquor freely drains through the drain conduits 40 back to the sump, not shown. The dye liquor is then pumped from the sump to be re-circulated with additional dye liquor into the inlet conduits 35. The drip pan 38 may be provided with an overflow weir 42 and drain outlet 43, if desired.