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METHOD AND APPARATUS FOR
SIMULTANEOUSLY EMBOSSING AND
PRINTING AN EXTRUDED PLASTIC SLAT
BACKGROUND INFORMATION 5
1. Field of Invention
This invention relates to decorating extruded plastic slat material for use in vertical or horizontal blinds, and, more particularly, to simultaneously applying an embossed relief pattern and an ink printed pattern to such material following its discharge from an extrusion die, with the printed pattern and the embossed relief pattern having a predetermined relationship with one another.
2. Description of the Related Art
A number of patents describe methods for applying an embossed texture pattern to extruded plastic slat material for vertical blinds. For example, U.S. Pat. No. 5,311,514 describes an assembly for forming or embossing a decorative pattern on at least one exposed surface of an elongated 20 slat, particularly of the type used in a vertical blind assembly. A pair of driven rollers engage opposite sides of a slat immediately after its formation by a plastic extruder. The exterior surfaces of one of the rollers has decorative patterns formed therein. The temperatures of the rollers are regulated 25 to facilitate transfer of the decorative pattern, continuous movement of the slat through the rollers, and formation of the transverse or cross-sectional configuration of the slat concurrently to placing the decorative pattern thereon. While such patents describe means for placing a texture 30 pattern on the slat, what is needed is a method for also applying a printed pattern, disposed in a preferred pattern related to the texture pattern, on the slat material.
A number of other patents describe various methods for providing slat material having color patterns and texture 35 patterns in registration with one another. For example, U.S. Pat. No. 4,842,036 describes vertical blind slat assemblies including laminates comprising strand material which is not free hanging and in which there are substantial spaces between strands to allow light to pass through the material, 40 and a sheet-like layer to which the strand material is secured, so that the strands of the laminate are fixed. The laminates allow the color or other characteristics of a slat member or insert to be seen. The laminates can have differing surface characteristics (e.g. texture) and strand colors, sizes, and 45 patterns. The laminate can be attached to the slat member directly, as by adhesive, or it may removably secured to a groover slat member. While the desirability of a pattern of raised or textured surfaces, with a corresponding color pattern, is thus recognized, what is needed is a method for 50 forming a slat having such patterns in an integral part, without requiring assembly procedures.
U.S. Pat. No. 4,116,737 describes a method for creating an embossed effect in a desired pattern on a film by printing an agent on the film in the desired pattern to lower the 55 stability of the film in the print areas against heat distortion and laminating the film to a substrate by fusion immediately after the substrate is extruded to cause the print areas to distort and give an embossed appearance as a result of the heat incident to the fusion. While this method is adapted for 60 simulating the texture of a wood grain pattern, what is needed is a method to form relatively large texture objects providing greater flexibility in the design of the texture pattern, and a method for forming an integral part without a need for laminating separate materials. 65
U.S. Pat. No. 4,223,057 describes a fabric containing thermoplastic fibers, which is simultaneously printed with a
first pattern in a sublimable or vaporizable dye and embossed or surface textured with a second pattern, without substantial effect on the printing of the first pattern, by the application of heat and pressure to a stack comprising a heat transfer printing sheet bearing a vaporizable or sublimable dye in the first pattern, an embossing sheet of material permeable to said dye and having no affinity or retention properties therefor, and having a second pattern formed in relief in at least one surface thereof, and a sheet of fabric to be printed and embossed. The printing and embossing sheets may be combined into a unitary sheet, and the embossing sheet may include a dye trap such as an emulsion or solution of an acrylic resin disposed in a third pattern. This process relates to the simultaneous heat transfer printing and embossing or surface texturing of fabrics and other sheet materials. What is needed is a method for using an embossing medium to carry inks for printing a desired pattern of color without requiring the use of a separate transfer sheet and without placing a requirement on the embossing material to allow transmission therethrough of a dye material. Also, what is needed is a method for simultaneously printing and embossing relatively thick and non-fiberous materials, such as slats for vertical blinds.
U.S. Pat. No. 6,006,816 describes a method in which extruded material for forming blind slats, and having at least one textured surface with raised areas and adjacent lower areas, is passed through a spray painting process applying a substantially thicker coating of paint to the raised areas than to the adjacent lower areas. While this method applies a colored paint image to slat material after it has been embossed, what is needed is a method having more control over the painted image, which also allows greater variations in parameters affecting the painted image, and a method simultaneously applying the embossed and printed image, which can be accomplished without the using a dedicated paint spray.
A number of other patents describe methods for applying ink to operating surfaces within printing apparatus. For example, U.S. Pat. No. 4,936,215 describes printing apparatus including a printing roller which abuts the cylindrical surface of an impression roller, in which ink is transferred from an anilox roller via the printing roller to the impression roller. What is needed is apparatus incorporating both a printing function and an embossing function for application to extruded slat material.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the present invention, a method, including steps of applying ink to a peripheral surface of an embossing roller and bringing the peripheral surface of the embossing roller into rolling contact with a surface of thermoplastic slat material, is provided for applying a decorative relief pattern to the surface of the slat material. The embossing roller includes an inverse relief pattern, which is an inverse of the decorative relief pattern. That is, the inverse relief pattern has grooves to form ridges in the decorative relief pattern, etc. The ink forms an ink layer extending along a portion of the peripheral surface of the embossing roller and varying in thickness in accordance to features of the inverse relief pattern. The inverse pattern forms the decorative relief pattern on the surface of the slat material, with a portion of the ink layer being transferred from the peripheral surface of the embossing roller to the surface of the slat material.
The inverse relief pattern preferably includes areas at various levels of depression from an outer surface level of
the inverse relief pattern. The ink layer is applied to the peripheral surface of the embossing roller from a transfer surface having an ink coating with a predetermined thickness, with the ink layer on the peripheral surface of the embossing roller decreasing in thickness with increases in 5 levels of depression from the outer surface level.
The inverse relief pattern preferably also includes areas having various textures, including smooth and rough areas, with the method additionally including a step of exposing the peripheral surface of the embossing roller to a stream of 1° air directed at the peripheral surface between the steps of applying ink to the peripheral surface and of bringing the peripheral surface into rolling contact with a surface of the slat material. This stream of air removes ink preferentially from smooth areas, while ink is retained in the rough areas. :5
This method may be applied only to a first side of the slat material, with the reverse side of the slat material remaining smooth, or the method may be applied to the second side of the slat material following its application to the first side, so that both sides are textured and colored with an ink pattern. 20
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a right end view of apparatus built in accordance with the present invention for simultaneously embossing 2s and printing extruded slat material;
FIG. 2 is a cross-sectional front elevation of the apparatus of FIG. 1, taken as indicated by section lines II—II therein;
FIG. 3 is a fragmentary transverse cross-sectional view of a portion of an anilox roller in the apparatus of FIG. 1, being 30 driven in contact with a transfer roller therein to apply a layer of ink to the transfer roller;
FIG. 4 is a fragmentary cross-sectional view of a portion of the transfer roller of FIG. 3, rolling in contact with an embossing roller in the apparatus of FIG. 1, to transfer a 35 layer of ink to the embossing roller;
FIG. 5 is a fragmentary transverse cross-sectional view of a portion of the embossing roller of FIG. 4, moving past an air stream from an air knife within the apparatus of FIG. 1; 4Q
FIG. 6 is a fragmentary transverse cross-sectional view of a portion of the embossing roller of FIG. 4, moving in rolling contact with the upper surface of the extruded slat material;
FIG. 7 is a fragmentary plan view of a pattern formed on the upper surface of extruded slat material within the appa- 45 ratus of FIG. 1;
FIG. 8 is a cross-sectional front elevation of apparatus built in accordance with the present invention for embossing and printing both sides of extruded slat material;
FIG. 9 is a plate for forming extruded slat material into a 50 convex shape within the apparatus of FIG. 8;
FIG. 10 is a front elevation of a vertical blind assembly including a number of slats processed within the apparatus of FIG. 1 or FIG. 8; 55
FIG. 11 is a fragmentary cross-sectional plan view of the vertical blind assembly of FIG. 10, taken as indicated by section lines XI—XI therein; and
FIG. 12 is a cross-sectional end elevation of a horizontal blind assembly including a number of slats processed within 60 the apparatus of FIG. 1 or FIG. 8.
DETAILED DESCRIPTION OF THE
FIGS. 1 and 2 show a first surface finishing station, 65 generally indicated as 10, built in accordance with the present invention for simultaneously embossing and printing
thermoplastic slat material 12 being extruded from a die 14 in the direction of arrow 16. The slat material 12 is, for example, composed of polyvinyl chloride. FIG. 1 is a right end view of the first surface finishing station 10, while FIG. 2 is a cross-sectional front elevation of the first surface finishing station 10, taken as indicated by section lines II—II in FIG. 1 to reveal internal details of the first surface finishing station.
The extruded slat material 12 is pulled between an embossing roller 18 and a back-up roller 20. Both of these rollers 18, 20, which are of metal construction, are rigidly and rotatably mounted within a first framework 22, with the back-up roller 20 being driven in the direction of arrow 23 by a motor 24. A drive belt 25 or suitable roller chain is used to drive the back-up roller 20 from the motor 24. The back-up roller 20 is rotatably mounted within a pair of stationary bearing blocks 26, which extend between frame posts 28 on each side of the rollers 18, 20. The embossing roller 18 is rotatably mounted in a pair of sliding bearing blocks 30, which are in turn mounted to slide in the vertical directions of arrow 32 between the frame posts 28. Each sliding bearing block 30 is held in place by an adjustment screw 33 extending downward from a cross-bar 34. The threads of the adjustment screw 33 engage a threaded hole within the cross-bar 34, while the sliding bearing block moves vertically with the lower end of the adjustment screw 33 as the screw 33 is turned. Each cross-bar 34 is mounted at the top of the frame posts 28 by means of air cylinders 36, which are used to hold the rolls 18,22 apart for maintenance of the first surface finishing station 10. The embossing roller 18 is preferably freely rotating, being rotationally driven in the direction of arrow 39 through the extruded slat material 12 by means of the rotation of back up roll 20.
The peripheral surface 40 of the embossing roller 18 includes the pattern to be embossed on the upper surface of the extruded slat material 12. This pattern on the peripheral surface 40 is reversed as required for the embossing process. The peripheral surface 42 of the back-up roller 20 is smooth, as required for backing-up the embossing process.
The speed of motor 24 is adjusted with the speed at which the slat material 12 is extruded from the die 14 so that excessive tension is not applied to the material 12, and so that excessive sagging of the material 12 is also prevented. A pair of guide posts 44 extending from the first framework 22 also minimize sagging, while controlling the angle at which the slat material 12 enters the rollers 18, 20. Each guide post 44 also has a pair of guiding collars 46, between which the slat materia 12 is drawn, to further control its position between the rollers 18, 20.
The first surface finishing station 10 also includes a printing station, generally indicated as 50, for applying a pattern of ink to the peripheral surface 40 of the embossing roller 18. The printing station 50 includes an ink cavity 52, an anilox roller 54, turning in the direction of arrow 56, which picks up liquid ink from the ink cavity 52, and a transfer roller 58, which carries at least a portion of this liquid ink from the anilox roller 52 to be deposited on the peripheral surface 40 of the embossing roller 18. Preferably, the transfer roller is rotationally driven in the direction of arrow 60 by contact with the peripheral surface 40 of the embossing roller 18, while the anilox roller 54 is driven in the direction of arrow 56 by the rotation of the transfer roller 58, through a gear train 62, extending between a shaft 64 attached to the transfer roller 58 and a shaft 66 attached to the anilox roller 54. The gear train is configured to drive the rollers 54, 58 at the same peripheral speed, including, for example, a main gear 68, 70 on each of the shafts 64, 66 and
a pair of idler gears (not shown) operating between these main gears 68, 70.
The printing station 50 also includes a pair of side plates 72 and an intermediate plate 74, which are used to mount various components, including the rotatably mounted shafts 5 64, 66. The ink cavity 52 is mounted by means of brackets 76 and shaft 78. The printing station 50 is pivotally mounted on a shaft 80, extending between mounting plates 82 forming part of a second framework 84. A pair of pneumatic cylinders 86, extending between an upper shaft 88 forming 1° part of the second framework 84, and a lower shaft 90, held within the side plates 72, are used to pivot the printing station 50 upward when this action is needed for maintenance.
The ink cavity 52 includes seals 92 extending around an 15 opening 93 and engaging a peripheral surface 94 of the anilox roller 54. Liquid ink is circulated through the ink cavity 52 by means of a pump 95 operating atop a paint supply reservoir 96, and is made available to the peripheral surface 94 through the opening 93 surrounded by seals 92. 20 Ink is pumped upward through a supply hose 98, and returned downward, to maintain circulation, through a discharge hose 100.
The first surface finishing station 10 preferably addition- 2J ally includes a cleaning tray 101, located under the back-up roller 20, which is partly full of water to clean ink from the back-up roller 20. This cleaning tray 101, which is partly filled with water, includes a sponge (not shown) in contact with the peripheral surface 42 of the back-up roller 20. 3Q
FIG. 3 is a fragmentary transverse cross-sectional view of a portion of the anilox roller 54 being driven in the direction of arrow 56 in contact with the transfer roller 64, showing a transfer of ink from the anilox roller 54 to the transfer roller 64. The peripheral surface 94 of the anilox roller 54 35 includes a number of roller cavities 102, which are, for example, 0.08 mm (0.003 inch) to 0.13 mm (0.005 inch) deep. Passing through the opening 93 in the ink cavity 52, these cavities 102 are at least partly filled with liquid ink 104. The peripheral surface 106 of the transfer roller 58 is 40 formed as a rubber coating 107 to which at least a portion of the liquid ink 104 within the roller cavities 102 is transferred within a contact region 108. The rubber coating 107 is, for example, 1.6 mm (0.062 inch) to 9.5 mm (0.375 inch) thick, having a durometer of 40-80. 45
FIG. 4 is a fragmentary transverse cross-sectional view of a portion of the transfer roller 58 rotating in the direction of arrow against the embossing roller 18. According to a preferred version of the present invention, the peripheral surface 40 of the embossing roller 18 includes a relief 50 pattern 110 to be embossed into an upper surface 112 of the extruded slat material 12, with the relief pattern 110 including areas having differing surface levels and textures. The relief pattern 110 is an inverse of the relief pattern to be produced on the surface of the slat material 12, in that, for 55 example, grooves in the relief pattern 110 form ridges in the relief pattern to be produced on the surface of the slat material. For example, the relief pattern 110 includes first areas 114 having a relatively rough surfaces extending downward 0.13 mm (0.005 inch) from the outer surface 60 level 116 of the peripheral surface 40, second areas 117 having smooth surfaces extending downward 0.25 mm (0.01 inch) from the outer surface level 116, and third areas 118 having smooth surfaces extending downward 0.37 mm (0.015 inch) from the outer surface level 116. When the 65 relief pattern 110 comes into contact with the liquid ink 104 being carried by the transfer roller 58, part of the ink 104 is
transferred from the transfer roller 58 to the relief pattern 110, with a greater proportion of the ink 104 being transferred to the areas, such as areas 114 which are least depressed from the outer surface level 116, and with a lesser proportion of the ink 104 being transferred to the areas, such as areas 118, which are the farthest depressed from the outer surface level 116. This process occurs, for example, because the limited thickness of the layer of ink 104 on the peripheral surface 106 allows the ink 104 to reach all of the level of the areas 114, but to reach only a portion of the areas 118.
Referring again to FIGS. 1 and 2, the first surface finishing station 10 additionally includes an air knife 120 mounted on a bar 122 extending between posts 28 as a part of the first frame 22. The air knife 120, which is supplied with compressed air through a hose 124, directs a stream of air radially toward the periphery 40 of the embossing roller 18.
FIG. 5 is a fragmentary transverse cross-sectional view of a portion of the embossing roller 18 moving past an air stream, indicated by arrows 126, from the air knife 120. The depth of the areas 114,117,118 from the outer surface level 116 has no significant effect on the movement of air past these areas 114, 117, 118. On the other hand, while air, represented by arrows 128, moving along the peripheral surface 40 of the embossing roller can remove paint particles or droplets 129 within the smooth areas 117,118, the rough surfaces of areas 114 provide a relief pattern of crevices in which paint is held without being removed by airflow. Much of the paint particles or droplets 130 removed by the airflow from the smooth areas 117,118, are redeposited on adjacent rough surfaces of areas 114. In this way, the depth of various areas of the relief pattern 110, and the texture of these areas provide separately variable but complimentary controls of the density of paint remaining on the areas of the relief pattern 110 after this relief pattern is moved by the air knife 120.
FIG. 6 is a fragmentary transverse cross-sectional view of a portion of the embossing roller 18 moving by the upper surface 112 of the extruded slat material 12. The embossing process forms a textured relief pattern 131 within the upper surface 112, with the relief pattern 131 being a reversal of the relief pattern 110 on the embossing roller 18. This process also transfers at least a portion of the ink previously remaining on the texture relief pattern 110 to the relief pattern 131. The density of ink deposited in various areas of the relief pattern 131 depends on the density of ink remaining on the corresponding areas of the relief pattern 110 after passage by the air knife 120. Thus, the relief pattern 131 is formed with rough areas 132 having more paint than smooth surfaces 134, and with raised areas 136 having less paint, if any paint.
FIG. 7 is a fragmentary plan view of an exemplary relief pattern 138 formed on the upper surface 112 of the extruded slat material 12. The relief pattern 138 represents a textile material, with a rough background area 140 and raised, but relatively smooth, areas 142 representing horizontal and vertical threads. Because the background area 140 is depressed within the relief pattern 138, and because the background area 140 is relatively rough, this area 140 is covered with a relatively high density of ink. Because the areas 142 representing threads are raised and relatively smooth, they are covered with a relatively low density of ink or with no ink at all. Preferably, the colors or levels of tint of the ink and the base material composing the extruded slat material 12 are contrasting, making the background area 140 and the areas 142 representing individual threads appear to be substantially different.
The processes for using both the texture and the relative height of features to determine variations in the color of