Abstract:
A method for embossing a cylindrical object such as a paint roller cover, especially using an apparatus that includes a shuttle and a rotatable shaft on the shuttle. The rotatable shaft includes two ends, with one end accepting a paint roller cover and with the other end being toothed for engagement with a gear rack. As the rotatable shaft is drawn in one direction by the shuttle, the toothed end engages the gear rack and rotates the rotatable shaft, thereby also rotating the paint roller cover. As the paint roller cover rotates, it is drawn by the shuttle over a die transfer plate having a design formed therein, and such design is transferred to the paint roller cover. The die transfer plate is heated to the desired temperature, and the speed of the shuttle is controllable so that time and temperature is controlled. Another controlled parameter is pressure.

Description:
This application is a divisional application of pending U.S. application, Ser. No. 09/131,977, filed on Aug. 10, 1998, now U.S. Pat. No. 6,203,309 and entitled APPARATUS FOR EMBOSSING PAINT ROLLER COVERS. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a method for embossing cylindrical objects, and specifically for embossing paint roller covers. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 5,713,095 discloses a bifurcated paint roller tool. The paint roller tool includes a pair of paint rollers wherein each of the paint rollers is rotatable independently of the other paint roller. The tool cooperates with a bifurcated paint tray such that each of the paint rollers is dippable in paint of a different color. The tool is then turned while rolling paint on a wall to mix the different colors while the paint is wet to produce a rag rolling like random paint effect. Each of the paint rollers includes a paint roller cover which is slideable on and off of the tool so that new or clean paint roller covers may be used. Such paint roller covers may include designs so as to add random or relatively ordered designs to the wall. As to such paint rollers or paint roller covers having designs or patterns, U.S. Pat. No. 5,713,095 issued Feb. 3, 1998 is hereby incorporated by reference in its entirety. 
     SUMMARY OF THE INVENTION 
     A feature of the present invention is an embossing apparatus for impressing designs into cylindrical objects. 
     Another feature is an embossing apparatus for impressing designs into the naps of paint roller covers. 
     Another feature is an embossing apparatus that simultaneously draws and rolls a cylindrical object over a die transfer plate. 
     Another feature is an embossing apparatus that includes a shuttle for drawing the cylindrical object over the die transfer plate. 
     Another feature is an embossing apparatus that includes a rotatable shaft on the shuttle, where the rotatable shaft engages the cylindrical object and rolls the cylindrical object over the die transfer plate. 
     Another feature is an embossing apparatus that includes ejection plates for pushing the cylindrical object off the rotatable shaft after the cylindrical object has been embossed. 
     Another feature is a method for embossing paint roller covers where the method controls the time and temperature of the embossing and further controls the pressure of embossing so that a pressure parameter is a variable. With a third variable such as pressure, a greater scope is permitted for the parameters of time and temperature and a greater scope of substrate materials for the nap is realized. 
     An advantage of the present invention is efficiency. Embossing of cylindrical objects, preferably paint roller covers, is accomplished inexpensively and quickly. 
     Another advantage is precision. The design of the die transfer plate is transferred exactly. The die transfer plates are flat and of course have definite edges. Yet the design or patterns that are transferred have no distinguishable starting point and no distinguishable ending point. 
     Another advantage is that the parameters of the method are easily changed. The time of engagement between the paint roller cover and die transfer plate may be easily changed by varying the speed of the motor driving the shuttle. The temperature of the embossing may be changed by changing the temperature of the die transfer plate. The pressure of the embossing may be incrementally changed by changing the height of the die transfer plate relative to the paint roller cover. The provision of an additional parameter such as pressure permits wider ranges for embossing times and temperatures which in turn permits a greater number of different substrates to be used as the nap. The manufacturer need not rely on one nap or one nap supplier. The manufacturer may offer a greater variety of designs and substrates for the paint roller covers. 
     These and further objects and advantages of the present invention will become clearer in light of the following detailed description of the illustrative embodiments of this invention described in connection with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the present apparatus for embossing paint rollers. 
     FIG. 2 is a top view of the embossing apparatus of FIG.  1 . 
     FIG. 3 is an end view of the embossing apparatus of FIG.  1 . 
     FIG. 4 shows the other end view of the embossing apparatus of FIG.  1 . 
     FIG. 5 is a side view of the rear of the embossing apparatus of FIG.  1 . 
     FIG. 6 is a perspective view taken from the rear of the embossing apparatus of FIG.  1 . 
     FIG. 7 is a detail perspective view taken from the rear of the embossing apparatus of FIG.  1 . 
     FIG. 8 is a detail perspective view taken from the rear of the embossing apparatus of FIG.  1 . 
     FIG. 9 is a detail perspective view taken from the front of the embossing apparatus of FIG.  1 . 
     FIG. 10 is a more detailed perspective view taken from the front of the embossing apparatus of FIG.  1  and shows the shuttle assembly and paint rollers approaching the die transfer plate. 
     FIG. 11 is a view similar to that of FIG.  10  and shows one paint roller being embossed and the other paint roller approaching the die transfer plate. 
     FIG. 12 is a view similar to that of FIG.  10  and shows one paint roller immediately after being embossed and the other paint roller in the process of being embossed. 
    
    
     DETAILED DESCRIPTION 
     As shown in FIGS. 1-12, the present apparatus for embossing paint rollers is indicated in general by reference numeral  10 . In general, the apparatus  10  includes a frame  12 , a base plate  14  on the frame  12 , a control unit  16 , a motor unit  18  for driving a first drive chain  20  and second shuttle chain  22 , the latter of which is engaged to and drives a shuttle assembly  23 . Shuttle assembly  23  includes a pair of shuttles  24 , each of which slides on a slide bed  26  and includes a pair of rotator shafts  28 . One end of each of the rotator shafts  28  frictionally receives a paint roller or paint roller cover  29  and the other end of each of the rotator shafts  28  has a spur gear  30  which meshes with a gear rack  32 . Each of the rotator shafts  28  is mounted in a pair of bearings  34 . As the shuttles  24  are driven by the second chain  22 , the rotator shafts  28  spin in their bearings  34  and the paint rollers  29  roll over heated die transfer or embossing plates  36  having designs or patterns  37  and pick up such designs or patterns  37 . After passing over the die transfer plates  36 , the paint rollers  29  are ejected by ejection wiper plates  38 . 
     More specifically, frame  12  includes a set of at least four legs  40  between which extend a set of four lower horizontally extending support members  42  and a set of four upper horizontally extending support members  44 . The base plate  14  is fixed on the set of four upper horizontally extending support members  44  and includes a set of three cut-outs  46 ,  48 ,  50  through which embossed paint rollers  29  may fall after being ejected. 
     Control unit  16  is fixed on the base plate  14  and includes circuitry (such as a programmable logic controller (not shown)) for controlling the motor unit  18  and the speed of the motor therein, the shuttling of the shuffles  24  including the speed and position of the shuttles  24 , the heating of the die transfer plates  36  including the temperature of the die transfer plates  36 , and the timing of the operation of the ejector wiper plates  38 . Control unit  16  includes a power supply, switches, timers, temperature controls and other such mechanisms (not shown) for control and operation of the apparatus  10 . 
     Motor unit  18  is fixed on base plate  14  and is preferably includes an electric motor. Motor unit  18  drives a toothed shaft  52  which engages the first chain  20 . Motor unit  18  includes a speed reducer (not shown) where a change in the voltage changes the speed or the rpm of shaft  52 . Motor unit  18  may include gearing to change the speed of shaft  52 . 
     Shuttle assembly  23  includes the shuttle chain  22 , shuttles  24 , and slide bed  26 . Shuttle assembly  23  further includes a pair of elongate angle irons  54  fixed to the base plate  14 . Sandwiched between the elongate angle irons  54  is the slide bed  26 . Slide bed  26  is an open ended tube that is rectangular in cross section. Slide bed  26  abuts base plate  14 . As best seen in FIG. 3, shuttle assembly  23  further includes a pair of slide rails  56  mounted on the slide bed  26  via threaded pin connectors  58  such that the slide rails  56  may be vertically adjustable. 
     Shuttle  24  includes an open ended housing which is formed as a base plate  60 , side plates  62  and an upper plate  64 . As shown in FIG. 3, a pair of slide rail receptors  68  are fixed to base plate  60  for receiving slide rails  56 . A pinching mechanism  70  is further fixed to the base plate  60  and includes a pair of half members that pinch the shuttle chain  22  between them and interlock with the shuttle chain  22 . 
     Shuttle chain  22  rides on and between a first toothed drive shaft  72  and a second toothed passive shaft  74 . Shafts  72 ,  74  are journaled to plates fixed to base plate  14 . Toothed drive shaft  72  includes a sprocket  76  that engages drive chain  20 . Shuttle chain  22  rides within and above slide bed  26  so as to isolate the portions of the chain  22  running in the opposite directions. 
     Shuttle assembly  23  further includes a rack gear first elongate base portion  78  fixed to base plate  14 . Base portion  78  is C-shaped in section. Vertically adjustably mounted on the base portion  78  via slot and pin connector mechanisms  79  is a rack gear second elongate base portion  80 . Second base portion  80  is L-shaped in section. Rack gear  32  is mounted on the L-shaped base portion  80 . 
     As indicated above, shuttle  24  includes the pair of rotator shafts  28  mounted in bearings  34 . Rear end of rotator shaft  28  includes the spur gear  30 . Spur gear  30  engages rack gear  32  such that the shaft  28  is trained relative to the base  14 . As the drive chain  22  pulls shuttle  24  in either of the directions, rotator shaft  28  is turned by such engagement between spur gear  30  and rack gear  32  so as to turn the paint rollers  29  which roll across the die transfer plates  36 . 
     Shuttle assembly  23  further includes position locator sensors (not shown). Position locator sensors may be located in shuttle  24  and cooperating sensors (not shown) may be fixed on rails  56 , angle iron supports  54  or in box  26 . Position locator sensors are preferably used to coordinate the timing of the operation of ejector plates  38  for the ejection of the paint roller covers  29 . 
     Die transfer plate  36  is mounted on heater plate  82  which in turn is mounted on a set of four threaded columns  84 , which in turn are mounted on heater adjustment plate  86 , which in turn is laterally and longitudinally adjustably mounted on heater base plate  88 , which in turn is mounted on base plate  14 . Heater plate  82  is incrementally drawable towards and away from heater adjustment plate  86  and thus base plate  14  to adjust the height of the die transfer plate  36  relative to the paint rollers  29 . Such height adjustment is accomplished by providing at least a pair of threaded nuts (not generally shown) on each of the columns  84  and by pinching the die transfer plate  36  between each of the respective pairs of threaded nuts. One such nut  87  is shown in FIG. 11 to illustrate that the height adjustment is an incremental adjustment. Height adjustment of die transfer plate  36  controls the pressure of the engagement between the plate  36  and the roller  29 . Further, height adjustment may control the depth of the embossments in a substrate or nap  98  on roller cover  29  so as to form embossments in nap  98  which terminate short of a roller base  100 . 
     Heater adjustment plate  86  is removably engaged with heater base plate  88  and is further laterally and longitudinally (i.e., right and left and in and out) adjustable relative to heater base plate  88  via pin and slot combinations  90  to provide for lateral and longitudinal adjustment of die transfer plate  36  relative to roller cover  29 . Heater base plate  88  is removably engaged with base plate  14 . 
     Heater plate  82  includes a set of four electric resistor elements  92  to heat the heater plate  82  to in turn heat the die transfer plate  36 . Preferably, the die transfer plate  36  is of a temperature sufficiently high to quickly melt the nap  98  of the paint roller cover  29  and sufficiently low so as not to burn the nap  98  or base  100 . Preferably, the temperature of the die transfer plate  36  is between about 250 degrees F. to about 600 degrees F. More preferably, the temperature is between about 270 degrees F. and about 560 degrees F. Most preferably, the temperature is between about 325 degrees F. and about 475 degrees F. Die transfer plate  36  is preferably formed of aluminum. 
     It should be noted that the temperature set by the control unit  16  may not be relied upon. Aluminum is a heat sink. Temperature readings may be most accurate if taken directly from the die transfer plate  36  itself. 
     It should further be noted that the temperature of the die transfer plate  36  may be dictated by the type of fiber of nap  98 . Such fiber may be a natural or synthetic fiber. A synthetic, plastic fiber is preferred. Polyethylene, polypropylene, and polycarbonate fibers are most preferred. 
     It should further be noted that the temperature of the die transfer plate  36  may depend upon the thickness of nap  98 . Preferably, the thickness of nap  98  is between about ⅜ inches and about {fraction (3/16)} inches. 
     The time of engagement of the paint roller cover  29  on die transfer plate  36  is preferably about 0.5 seconds to about 20 seconds and more preferably about two seconds to about ten seconds. An excessively long engagement may burn the nap  98  or roller base  100 . An excessively short engagement may incompletely melt the desired portions of nap  98  and lead to an incomplete design transfer. 
     Besides time and temperature, pressure of engagement between the roller cover  29  and die transfer plate  36  is a parameter to be taken into consideration. At high temperatures, it may be desirable to set the pressure of such engagement fairly high and to quickly engage the roller cover  29  and the die transfer plate  36 . 
     The design  37  of the die transfer plate  36  is preferably machined into die transfer plate  36 . Instead of being machined in, the design  37  may be cut into the plate  36  with a laser or etched in chemically. 
     Ejector wiper plates  38  are effectively piston heads mounted on piston shafts extending through guide holes in ejection guide plate  94 . Ejection guide plate  94  is fixed to upper plate or ejection base plate  64 . Pneumatic piston and cylinder mechanisms for the ejector wiper plates  38  may be located in pneumatic housing  96  mounted on ejection base plate  64 . Ejector wiper plates  38  annularly confront the rotatable shaft  28  and are slideable along the rotatable shaft  28  from the ejector guide plate  94  to a distal end  31  of the rotatable shaft  28  so as to completely push the paint roller cover  29  off the rotatable shaft  28  so that the paint roller cover  29  falls by gravity off the rotatable shaft  28 . It should be noted that the ejector wiper plates  38   15  annularly confront the rotatable shaft  28  for about 270 degrees about the rotatable shaft  28 . Such an annular confrontation terminates short of a bottom portion of rotatable shaft  28  to permit the wiper plates  38  to be spaced from die transfer plate  36  as such wiper plates  38  wipe off the roller cover  29  and “wipe over” without touching the die transfer plate  36 . 
     Paint roller  29  or paint roller cover  29  includes a nap  98  and a cylindrical base  100 . Nap  98  may be a natural or synthetic fiber. Cylindrical base  100  may be a hard or semi-rigid plastic or formed of a hard or semi-rigid paper base. Rotator shaft  28  includes removably fixed thereto a ring  102  (shown in FIG. 7) against which the cylindrical base  100  of the paint roller  29  abuts as the paint roller  29  is slid onto the  25  rotator shaft  28  so that the paint roller  29  may be quickly slid onto the rotator shaft  28  to the proper distance. Transverse movement of rotator shaft  28  may be prevented by rings (not shown) removably fixed to rotator shaft  28  on either side of bearings  34 . 
     The design  37  of the design transfer plate  36  includes relatively raised portions  104  and relatively low portions  106 . The depth of such relatively low portions  106  is preferably greater than the height or radial distance of nap  98  from base  100  so as to preferably leave untouched the outer surface of the nap portions which extend into the relatively low portions  106 . Relatively raised portions  104  that melt the portions of the substrate or nap  29  impress or emboss such design  37  into the nap  98 . 
     Die transfer plate  36  preferably has a nonstick coating of a heat resistant polymer or copolymer. More preferably, the heat resistant polymer or copolymer is a fluoroplastic. Most preferably, the fluoroplastic is PTFE. 
     The length of the die transfer plate  36  is preferably exactly the circumference of the outer surface of the cylindrical base  100  so that, after rolling, a nap design portion at zero degrees matches such nap design portion at 360 degrees. In other words, the distance between parallel edges  108  and  110  of die transfer plate  36  is exactly equal to the circumference of the outer surface of the cylindrical base  100 . In still other words, the design or pattern  37  that is transferred to the nap  98  has no distinguishable starting point and no distinguishable ending point. A continuous pattern, continuous for more than 360 degrees about the nap  98 , may be formed. 
     In operation, the temperature of the die transfer plate  36  is selected in light of the material to be embossed, such as the material forming nap  98 . The speed of the roll of the nap  98  across the die transfer plate  36  is also selected by adjustment of the speed reducer or gearing in the motor unit  18 . Accordingly, a relatively slow roll may be provided across a relatively hot die transfer plate  36  or a relatively fast roll may be provided across a relatively cold die transfer plate  36 . Or a relatively fast roll may be provided across a relatively hot die transfer plate  36 . Or a relatively slow roll may be provided across a relatively cold die transfer plate  36 . Further parameters to select are the pressure of the engagement between the die transfer plate  36  and the roller  29  (accomplished by selecting the height of the die transfer plates  36 ) and the timing of the ejection of the paint rollers  29  after embossing by the ejector wiper plates  38 . Further as to pressure, a quicker embossment step may be provided by selecting a relatively high temperature for the die transfer plate  36  and a relatively high pressure engagement between the plate  36  and the roller  29 . 
     After the parameters have been selected, the paint rollers  29  are fed onto the rotator shafts  28 , such as by hand or robotic mechanism, so as to abut against rings  102 . The paint rollers  29  fit with sufficient friction on the shaft  28  so as to be difficult to rotate by hand. Such friction minimizes a spinning of the roller  29  relative to the shaft  28 , maximizes the ease of axially pushing the roller  29  onto the shaft  28  by hand and maximizes the ease of axially pushing of the roller  29  off the shaft  28  via the ejection plates  38 . Drive belt  22  then pulls the shuttle  24  in the direction of die transfer plates  36 , thereby drawing the spur gears  30  across gear rack  32 , thereby in turn rotating the rotator shafts  28  and paint rollers  29 . Paint rollers  29  thereby are rolled across die transfer plates  36  by the rotator shafts  28 . As the naps  98  roll across the hot die transfer plates, the relatively raised portions  104  impress the design  37  into the naps  98  by melting the fibers of the nap  98 . After each of the paint rollers  29  is rolled across its respective die transfer plate  36 , its respective ejector wiper plate  38  is extended to the distal end  31  of shaft  28  to push the paint roller  29  off its respective rotator shaft  28 . Such paint roller  29  then falls through its respective cut-out portion  46  or  48  or  50 . 
     An unembossed paint roller  29  is then placed preferably immediately on the rotator shaft  28  such that such unembossed paint roller  29  is placed on the shaft  28  after an embossed paint roller  29  has been ejected from such rotator shaft  28  and prior to the rotator shaft  28  returning back across the die transfer plate  36 . In other words, paint rollers  29  may be embossed as the shuttle  24  slides in one direction and again as the shuttle  24  slides in the opposite direction. Embossed paint rollers  29  may thus fall through each of the cut-out portions  46 ,  48 , and  50  and are almost immediately ready for shipment or use, such as use with a bifurcated paint roller tool. 
     Thus since the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalents of the claims are intended to be embraced therein.