The present invention relates to an apparatus for slitting a moveable web of corrugated paperboard and, more particularly, to a lubricator system that uses Teflon or other suitable lubricant pucks or blocks that are physically pinched or loaded onto a slitting blade to assist in sharpening of said blade and to prevent build-up of starch or similar adhesive associated with the production of the corrugated paperboard.
A slitter/scorer is used on the dry end of a corrugator to slit and score the corrugated web emerging from the double backer so as to create multiple independent “outs” that can be routed to the upper or lower level of a cutoff knife. The knife then cuts these “outs” to designated lengths to create the independent sheets that are then stacked. The slitting tool used to slit the web is a thin blade of approximately 1-2 mm in thickness that rotates at high speed with the corrugated web supported below the blade by a rotating solid anvil as described in U.S. Pat. No. 5,090,281, the disclosure of which is incorporated by reference herein.
The web that is slit is formed in and emerges from an upstream double backer with a green bond of the starch adhesive on the lower liner that has a propensity to adhere to the thin slitting blade. A standard approach to prevent starch from building up on the thin blade involves wiping a lubricating fluid onto the blade using a wick lubricator pad. A pressurized oil feed is used to wet the wick. The wick is replaced at frequent intervals to insure a fresh surface free of starch accumulation.
There are several problems with this conventional approach to thin blade lubrication. First, there is potential for over lubrication and wetting of the wicks that can result in dripping of lubricant onto the top of the board, particularly at corrugator stop. Also, to the extent that the wick wipes the lubricant on the blade, this same lubricant can contaminate the edges of the corrugated board.
To address this issue and to make this problem acceptable to corrugated manufacturers who are manufacturing board for food-grade applications, a food-grade acceptable lubricant is necessary. This is expensive and not universally acceptable. Also, the food-grade lubricant works less well than, for example, a WD-40 type lubricant. Another problem is associated with the pumps and valves and lubricant lines that have to be routed to the slit blades resulting in a complicated and maintenance-intensive system. Lubricant must be stirred to prevent coagulation. Valves become stuck. Lubrication pads need to be changed on at least a daily basis and this is expensive and labor intensive.
A recently introduced solution to the lubrication problem involves use of a polytetrafluoroethylene (PTFE) block as an anvil. This concept is described in U.S. Patent Application Publication US2006/0075864 A1 with publication date Apr. 13, 2006. The thin slitting blade plunges into the anvil and the PTFE block then lubricates the blade as it rotates in the PTFE support. As the blade wears away the PTFE, the blocks can be laterally shifted to create a new PTFE wear block.
This solution to lubrication creates a problem on long runs between order changes where the PTFE wears. Without an order change, it is not possible to shift the block to solve the wear issue. Also, the constant lateral feeding of PTFE blocks into the machine is labor intensive and is not routinely done by plant operating personnel. As the thin blade is plunged into the PTFE block, it works effectively, but as it wears, the effectiveness of the lubrication rapidly decreases.
The present invention is directed to a method and apparatus for lubricating the thin blade with a dry lubricant that is self compensating with wear of the lubricating means.
One object of this invention is to provide a slitting device that is particularly suited to slitting of corrugated paperboard without deformation of the edges of the board as a consequence of build-up of starch adhesive on the slitting blade.
Another object of the invention is to allow continuous operation of the slitting process without requirement to interrupt the process flow so as to maintain effective operation of the slitter.
Another object of the invention is to maintain even, effective slitting performance throughout the useful wear life of the thin blade lubricating means.
Yet another object is to eliminate the problem of dripping of wet lubricant on the corrugated board by use of a dry lubricating means. It is also an object of this invention to simplify the process of blade lubrication by elimination of lubricating lines, pumps, filters, stirring systems, and valves associated with prior art wet lubricating systems.
These and other objects and advantages are achieved by use of continuously loaded wear pucks of PTFE, or other lubricating material, onto each side of the thin blade used for slitting of the corrugated paperboard web. In this embodiment, the pucks are loaded against the blade edge with continuous adjustment using springs, air cylinders, or other load biasing means well known to those skilled in the art. There is a puck for each side of the thin blade. Each puck may have its own loading system. The pucks are retained or captured within a fixed lubricator housing that is carried on the tool head that carries the slitting blade. The loading system is mounted to the outside of the housing and in one embodiment, attaches via a loading plunger or rod through a suitable opening in the lubricator housing. The lubricator pucks may float within the housing so that they can achieve the correct contact surface with the sharpened cutting edge of the thin slitting blade. In one embodiment of the invention, there are lubrication housings on each side of the blade offset from one another. This allows the lubricator pucks to travel laterally beyond the tip of the blade on the outer edge as the blade wears.
In another embodiment of the invention, a single puck is radially loaded against the rotating thin blade with the natural spring force of the puck material loading the bifurcated sides of the puck against the opposing edges of the thin blade.
One particularly appealing feature of the puck lubrication apparatus is that lubricant can be applied at a position around the periphery of the blade other than the point of contact of the thin blade with the corrugated board. This makes it possible to use effective board support means such as the slotted anvil of U.S. Pat. No. 6,837,135.
Since the lubricator pucks are continuously loaded against the thin blade, the puck maintains contact with the blade as it wears in the lubrication transfer process. The pucks may also be free floating to the point that they adapt to the blade as the blade wears during the blade sharpening process. It is particularly advantageous that the loading of the lubrication puck against the blade occurs continuously during rotation of the blade with no interruption of the slitting process required to adjust the puck.
In another embodiment of the invention, the loading means can be retracted by physical means or automatically to avoid continuous lubrication of the blade while it turns but is not in use as a selected tool in the slitting process, or when intermittent lubrication is acceptable.
Yet another problem associated with the PTFE block is the requirement to adjust the relative position of the blade being lubricated by the block. As the blade wears and the radius decreases, the blade must be frequently discretely adjusted to maintain an effective position of the blade in the block.
In yet another embodiment of the invention, a pair of PTFE rods are positioned in an “X” type configuration and continuously biased in a radial direction against the blade to be lubricated. The rods pivot about their base and are biased to create a force on each rod that acts normal to the end of the rod forcing the rod into contact with the blade edge. This results in a variable loading of the rods onto the blade as a function of how deeply the blade is biased into the throat of the crossed rods.
There may be several formats of lubrication pucks other than PTFE that could provide the necessary starch release protection on the slitting blades and any suitable solid puck lubricant used would be within the scope of the invention.
Referring initially to
In a similar manner, lateral positioning of the anvil roll assembly 15 on the lower counterhead 14 utilizes a lower servomotor 25 driving a pinion 26 that engages a lower linear rack 27 attached to the lower box beam 21 and extending parallel to the lower linear way 20.
In a typical slitting apparatus 10, multiple pairs of upper and lower tool heads 12 and 14, respectively, are positioned along their respective box beams 16 and 21. Each of the upper tool heads 12 carries a rotatable drive assembly 28 including a center drive hub 30 with a hexagonal throughbore that receives a hexagonal shaft 31. The drive assembly 28 is operable to drive the slitting blades 13 and to permit their positioning in the cross machine direction on the hexagonal shaft 31 utilizing suitable microprocessor control. The upper tool head 12 typically carries a blade sharpener 33 for each slitting tool head for on-the-fly sharpening.
In accordance with the present invention, the tool head 12 also carries a contact blade lubricator 34 that improves upon and replaces the wet lubricator pads of the prior art as discussed above. One embodiment is shown in
Referring particularly to
Each puck 36 is biased laterally (perpendicular to the slitting blade 13) by a spring plunger 43 or other biasing device. The spring plunger 43 maintains the puck in intimate contact with the cutting blade edge and edge faces as the puck wears and as the blade diameter is reduced as a result of on-the-fly sharpening by the blade sharpener 33. Each spring plunger 43, which is of conventional construction, is mounted in a casing 44 attached to a side face of the housing 35. Within the casing 44 there is located a plunger head that bears directly on the puck 36 under the biasing influence of a spring 46. Multiple spring plungers may be used with each puck.
As the pucks are worn away by contact with the slitting blade and the slitting blade itself is worn by operation of the blade sharpener 33, the pucks assume a cross sectional shape shown in
In
The presently preferred embodiment of the invention is shown in
The upper end wall 64 and lower end wall 65 of the housing 54 are provided, respectively, with end wall slots 66 and 67 that extend from the open end face 57 toward the rear housing end face 68. Both slots 66 and 67 provide clearance for the slitting blade 13 as it penetrates the lubricant block biased into engagement therewith. The lower end wall slot 67 is just wide enough to provide the necessary blade clearance. The upper end wall slot 66 is somewhat wider and provides a clear view of slitting blade penetration into the lubricant block such that the useful life of the block can be visually monitored. In the embodiment shown, total blade penetration into the lubricant block may be about 1 inch (25 mm), but the size of the housing 54 and lubricant block 55 may be varied widely to provide a much greater blade penetration. The rate of blade penetration into the block 55 and the effective wear life of the block may be varied considerably depending on the bias force and the hardness of the PTFE block. For example, in one embodiment of the invention, the blade may penetrate the block at a rate of 0.0001 inch (0.0025 mm) per minute. At this rate, and assuming a maximum penetration of 1 inch (25 mm), the block would last up to 165 hours before replacement would be necessary. As may be seen in
In certain applications, it is possible that, as the slitting blade penetrates the lubricant block, the separated halves 71 of the slit block, only one of which is shown in
This application relates to and claims priority from U.S. Provisional Application Ser. No. 61/232,961 filed on Aug. 11, 2009.
Number | Name | Date | Kind |
---|---|---|---|
2134018 | Alderman | Oct 1938 | A |
2741281 | Braun | Apr 1956 | A |
2796933 | De Gelleke | Jun 1957 | A |
2895553 | De Gelleke | Jul 1959 | A |
3452734 | Cleland et al. | Jul 1969 | A |
3563285 | Thrasher | Feb 1971 | A |
3593763 | Neild | Jul 1971 | A |
3674065 | Fairfield et al. | Jul 1972 | A |
4028973 | Bogdanski et al. | Jun 1977 | A |
4635513 | McGeehee | Jan 1987 | A |
4848200 | McGehee | Jul 1989 | A |
4873759 | Burch | Oct 1989 | A |
4896793 | Briggs et al. | Jan 1990 | A |
4983145 | Hirai et al. | Jan 1991 | A |
5054582 | Aracil | Oct 1991 | A |
5090281 | Paulson et al. | Feb 1992 | A |
5159866 | Dunham | Nov 1992 | A |
5165314 | Paulson et al. | Nov 1992 | A |
5197366 | Paulson et al. | Mar 1993 | A |
5393174 | Wawrzyniak | Feb 1995 | A |
5406869 | Prochnow et al. | Apr 1995 | A |
5435217 | Kato et al. | Jul 1995 | A |
RE35086 | Paulson et al. | Nov 1995 | E |
5494368 | Matthews | Feb 1996 | A |
5616406 | Nakamaru et al. | Apr 1997 | A |
5667347 | Matthews | Sep 1997 | A |
5925299 | Dierckes et al. | Jul 1999 | A |
5971342 | Sakai et al. | Oct 1999 | A |
6128990 | Drew et al. | Oct 2000 | A |
6165117 | Adami | Dec 2000 | A |
6431037 | Dai et al. | Aug 2002 | B1 |
6826993 | Michalski | Dec 2004 | B2 |
6837135 | Michalski | Jan 2005 | B2 |
7299727 | Gravely et al. | Nov 2007 | B2 |
7325473 | Belfiglio | Feb 2008 | B2 |
20050183559 | Rue | Aug 2005 | A1 |
20060075864 | Adami | Apr 2006 | A1 |
20080105096 | Gravely et al. | May 2008 | A1 |
20080236354 | Esposito | Oct 2008 | A1 |
20110036220 | Paulson et al. | Feb 2011 | A1 |
Number | Date | Country | |
---|---|---|---|
20110036220 A1 | Feb 2011 | US |
Number | Date | Country | |
---|---|---|---|
61232961 | Aug 2009 | US |