Apparatus for dry lubrication of a thin slitting blade

Abstract

A block of a solid lubricant material, such as PTFE, is biased continuously or intermittently against the cutting edge of a rotary slitting blade for corrugated paperboard. The solid lubricant block prevents the build up of starch adhesive and biasing movement compensates for wear of the block and wear of the cutting blade edge.

Claims

1. A dry lubrication system for a web slitting machine including an annular rotary slitting blade for slitting into a running corrugated paperboard web, the dry lubrication system comprising: a first puck and a second puck of plastic lubricant held proximate a cutting edge of the slitting blade, the first puck contacting a first blade face of the slitting blade at a first blade face location and the second puck contacting a second, opposite blade face of the slitting blade at a second blade face location that is not immediately opposite the first blade face location, such that the first and second pucks are situated diagonally across the slitting blade from each other; and a first biasing mechanism that applies an external load to the first puck and thereby biases the first puck into continuous, generally uniform contact with the first blade face; wherein biasing of the first puck compensates for wear of the first puck due to contact with the first blade face and for wear of the blade cutting edge due to sharpening and continually advances the first puck in a lateral direction, perpendicular to the first blade face, to maintain the continuous, generally uniform contact as the first puck is worn away by the slitting blade.

2. The dry lubrication system of claim 1, further comprising a second biasing mechanism applying an external load to the second puck and biasing the second puck into continuous, generally uniform contact with the second blade face.

3. The dry lubrication system of claim 2, wherein the first and second pucks are biased independently of one another into contact with the first and second blade faces, respectively.

4. The dry lubrication system of claim 2, wherein the first and second pucks are biased generally perpendicularly with respect to the first and second blade faces, respectively.

5. The dry lubrication system of claim 2, further comprising a lubricator housing supported by the web slitting machine and having an open operating face for insertion of the blade cutting edge therein, wherein the first and second pucks are held within the lubricator housing.

6. The dry lubrication system of claim 5, wherein the lubricator housing comprises first and second opposing side faces joined by first and second opposing end walls, the first and second opposing end walls each having a slot there through to accommodate the blade cutting edge when the blade cutting edge is inserted into the lubricator housing via the open operating face.

7. The dry lubrication system of claim 6, further comprising first and second puck holders in the lubricator housing for holding the first and second pucks, respectively, and that nest the first and second pucks for limited movement toward the first and second blade faces, respectively.

8. The dry lubrication system of claim 7, wherein the first and second puck holders are seated in diagonally opposite open spaces in the lubricator housing, each puck holder having a short leg that contacts a respective one of the first and second pucks and holds the respective puck in a corner formed by one of the first and second side faces and one of the first and second end walls of the lubricator housing, and a long leg that contacts an opposing other of the first and second end walls to brace the short leg of the respective puck holder in place against the respective puck.

9. The dry lubrication system of claim 6, wherein the first biasing mechanism is supported by the first side face of the lubricator housing and the second biasing mechanism is supported by the opposing second side face of the lubricator housing.

10. The dry lubrication system of claim 2, further comprising first and second lubricator holders on opposite sides of the slitting blade that hold the first and second pucks in contact with the first and second blade faces, respectively.

11. The dry lubrication system of claim 10, wherein the first and second lubricator holders are circumferentially offset from one another with respect to the slitting blade.

12. The dry lubrication system of claim 11, wherein the first and second biasing mechanisms are supported by the first and second lubricator holders, respectively.

13. A dry lubrication system for a web slitting machine including an annular rotary slitting blade for slitting into a running corrugated paperboard web, the dry lubrication system comprising: a lubricant holder box supported by the web slitting machine and having first and second opposing side faces connected by first and second opposing end walls, and an open operating face for insertion of a cutting edge of the slitting blade therein; first and second lubricant pucks held within the holder box, the first puck positioned proximate the first end wall of the holder box and contacting a first blade face of the slitting blade at a first blade face location and the second puck positioned proximate the second end wall of the holder box and contacting a second, opposite blade face of the slitting blade at a second blade face location that is not immediately opposite the first blade face location, such that the first and second pucks are situated diagonally across the slitting blade from each other; and first and second biasing mechanisms that apply external loads to the first and second pucks, respectively, so as to continuously advance the first and second pucks in a lateral direction, perpendicular to the first and second blade faces, against and into continuous contact with the first and second blade faces, respectively, as the first and second pucks are worn away by the slitting blade.

14. The dry lubrication system of claim 13, further comprising first and second liquid lubricant-retaining wicks held within the holder box, wherein the first and second pucks are nested between the first and second wicks and the first and second blade faces, respectively.

15. The dry lubrication system of claim 14, wherein each of the first and second wicks has a stepped construction including a thinner portion adapted to seat the respective first or second puck therein and a thicker portion that contacts a respective one of the first and second blade faces.

16. The dry lubrication system of claim 15, wherein the first and second biasing mechanisms provide first and second biasing forces through the first and second opposing side faces of the holder box against the thinner portions of the respective first and second wicks, which first and second biasing forces in turn press the first and second pucks against the respective first and second blade faces.

17. The dry lubrication system of claim 13, wherein the first and second biasing mechanisms comprise spring-actuated mechanisms.

18. The dry lubrication system of claim 13, wherein the first and second biasing mechanisms comprise pneumatically-actuated mechanisms.

19. The dry lubrication system of claim 13, wherein positioning of the first puck proximate the first end wall of the holder box and of the second puck proximate the opposing second end wall of the holder box causes the first and second pucks to be circumferentially offset from one another with respect to the slitting blade.

20. The dry lubrication system of claim 13, wherein the first and second pucks comprise blocks of PTFE.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a side elevation view of a conventional web slitting apparatus on which is mounted a blade lubricator of the subject invention in its presently preferred embodiment;

(2) FIG. 2 is an enlarged perspective detail of the web slitting apparatus of FIG. 1 showing the preferred embodiment of the prevent invention in greater detail;

(3) FIG. 3 is an exploded view of the components of the invention shown in FIG. 2;

(4) FIG. 4 is a side elevation detail of the blade lubricator shown in FIGS. 1-3 in its initial operative position;

(5) FIG. 5 is a sectional view taken on line 5-5 of FIG. 4;

(6) FIG. 6 is a side elevation detail similar to FIG. 4 showing a position of the blade lubricator as the contact lubricator is cut away in use;

(7) FIG. 7 is a sectional view taken on line 7-7 of FIG. 6;

(8) FIG. 8 is a sectional view similar to FIG. 7 showing an addition to the FIG. 7 embodiment;

(9) FIG. 9 is a side elevation of a web slitting apparatus showing an alternate embodiment of the invention that is repositioned with respect to the slitting blade;

(10) FIG. 10 is a sectional detail taken on line 10-10 of FIG. 9;

(11) FIG. 11 is a sectional detail similar to FIG. 10 showing another embodiment thereof;

(12) FIG. 12 is a sectional detail of yet another embodiment of the invention;

(13) FIGS. 13A and 13B are sectional details showing wear patterns developed in alternate embodiments of the invention; and

(14) FIG. 14 is a side elevation of a web slitting apparatus showing an alternate embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(15) Referring initially to FIG. 1, a web slitting apparatus 10, suited particularly for slitting a moving corrugated paperboard web 11, includes an upper tool head 12 carrying a rotary slitting blade 13. A lower counterhead 14 is mounted below the web and carries a web-supporting anvil roll assembly 15. The upper tool head 12 is supported for lateral movement in the cross machine direction on a pair of linear bearing ways 17 that are attached to the underside of an upper box beam 16. Similarly, the lower counterhead 14 is supported for lateral movement in the cross machine direction on a lower linear way 20 mounted on the upper face of a lower box beam 21. Upper tool head 12 is moved along the upper linear ways 17 to position the slitting blade 13 by an upper servomotor 22 driving a pinion 23 that engages a linear rack 24 attached to the upper box beam 16 and extending parallel to the linear ways 17.

(16) 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.

(17) 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.

(18) 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 FIGS. 9 and 10. The blade lubricator 34 includes a housing 35 mounted in a stationary position on the upper tool head 12. Within the housing, there are mounted a pair of solid lubricant pucks 36, preferably made of polytetrafluoroethylene (PTFE). The pucks 36 are mounted within the housing 35 on opposite sides of the slitting blade 13. Each puck is seated within the housing 35 in a puck holder 37 secured within the housing, but allowing limited movement of the pucks to engage both faces of the blade edge.

(19) Referring particularly to FIG. 10, the lubricator housing 35 preferably comprises a box-like structure having an open interior substantially closed on five sides, but having an open operating face 38. The end walls 40 of the housing 35 are provided with slots 41 which, together with the operating face 38, accommodate entry of the slitting blade 13. Each of the puck holders 37 is secured in the housing 35 by gluing or other attachment means. The puck holders 37 have an L-shaped cross section including a short leg 42 that, together with the open interior of the housing 35, nest the pucks 36 for limited movement toward the blade 13 with a puck positioned on and in bearing contact with each side of the blade edge. The pucks are mounted such that they are spaced circumferentially with respect to the circular blade edge.

(20) 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.

(21) 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 FIG. 13A in which the radially outer portion 47 of the puck remains essentially unworn and retains its full thickness, but thins in the radially inward direction. Thus, the pucks 36 must be separated or spaced circumferentially with respect to the blade so that the unworn radially outward portions 47 of the pucks do not interfere with one another as the pucks are worn away. FIG. 11 is a view similar to FIG. 10 in which the biasing arrangement utilizes an air cylinder 48 to bias each puck into contact with the slitting blade edge. Otherwise, this embodiment is the same as that shown in FIG. 2.

(22) In FIG. 12, there is shown a further embodiment of the blade lubricator of the present invention. In this arrangement, a pair of circumferentially spaced solid lubricant pucks 50 are biased into contact with the outer blade edge by a pair of spring plungers 51 which may be the same as or similar to the spring plunger 43 described above. The plungers may include a retractable feature as is well known with these devices. The pucks 50 are nested in a liquid lubricant-retaining wick 52. Each of the wicks 52 has a stepped construction such that a puck 50 is seated in the thinner portion of the wick which, together with an identical but reversed puck and wick for the other side of the blade, are inserted and held in the housing 49 through an open end face 53. Each side of the housing 49 carries a spring plunger 51 which is operatively biased through the side wall of the housing against the thinner stepped portion of the wick 52. The bias force, in turn, presses the pucks 50 against the side faces of the slitting blade edge. This construction provides an advantage in applications where the starch adhesive used in the manufacture of the web 11 utilizes a particularly aggressive formulation that might tend to build up unacceptably if only solid lubricant pucks are used.

(23) In another example as shown in FIG. 14, the pucks 36 are held by first and second lubricator holders 80, 82 proximate respective first and second opposing sides of the slitting blade 13. The separate first and second lubricator holders 80, 82 hold the first and second pucks 36 on each side of the blade 13 in contact with the first and second blade faces, respectively. Additionally, the first and second lubricator holders 80, 82 are circumferentially offset from one another with respect to the slitting blade 13. As described herein above, this allows the lubricator pucks 36 to travel laterally beyond the tip of the blade on the outer edge as the blade wears. The first and second biasing mechanisms are supported by the first and second lubricator holders 80, 82, respectively (see FIGS. 10-12).

(24) The presently preferred embodiment of the invention is shown in FIGS. 2-8. In this embodiment, a lubricator housing 54 holds a rectangular block of solid lubricant 55 and the block and housing together are biased radially into contact with the circular edge 56 of the slitting blade 13. The lubricator housing 54 is a rectangular box-like enclosure, substantially closed on all sides, except for an open end face 57 through which the rectangular lubricant block 55 is inserted. Conveniently, the housing may comprise two mirror halves bolted together as shown. The housing 54 is supported on the blade head 58 with a pivotal attachment 60 permitting pivotal movement of the housing 54 and lubricant block 55 between a non-contact inoperative position (shown in phantom in FIG. 6) and an operative position with the block 55 biased into contact with the blade edge (shown in FIG. 4). The pivotal attachment 60 includes a pivot shaft that extends between and interconnects an inner side wall 62 of the housing 54 and the blade head 58. In one example, the pivot shaft 61 extends from the blade head 58 and through an aperture 94 in a corner of the housing 54 that is distal the blade 13. The pivot shaft 61 carries a biasing mechanism, which in one example comprises a torsion spring 63, the ends of which operatively interconnect the housing inner side wall 62 with the blade head 58. For example, a first end 90 of the torsion spring 63 is seated on the blade head 58 and a second end 92 of the torsion spring 63 is seated on the housing 54. (See FIGS. 2, 3, 5, and 7.) The force of the torsion spring 63 biases the housing 54 and lubricant block 55 against the edge of the slitting blade 13.

(25) 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 FIGS. 6 and 7, the slitting blade 13 penetrates the block 55 in a generally diagonal path as best seen in FIG. 6. From this position, the housing and slit block may be pivoted to the inoperative position and the block reversed in the housing 54.

(26) 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 FIG. 13B, may become more flexible and not provide adequate bearing contact with the opposite blade faces near the blade edge. In this case, it may be desirable to provide a supplemental lateral blade force to bias the lubricant block halves toward one another. As shown in FIG. 8, this can be most easily accomplished by using a biasing mechanism, such as, for example, a retractable spring plunger 70 that may be the same as the spring plunger 43 described above. The spring plunger 70 is coupled to, and in one example, mounted in the outer side wall 59 near the open end face 57 and the upper end wall slot 66 such that, when the spring is released, the head of the spring plunger 70 will bear against the side of the lubricant block and squeeze the two slit block halves 71 more tightly together. Although an oppositely disposed spring plunger 70 could also be used, a single plunger 70 is believed to be adequate. In the example shown, in FIG. 8, the spring plunger 70 is a biasing mechanism that is coupled to the inner side wall 62 of the housing 54 and that bears against a first side 96 of the lubricant block 55. Another spring plunger 70 may be provided in the outer side wall 59 and bear against a second, opposite side 98 of the lubricant block 55.

(27) FIG. 6 shows the lubricant housing and lubricant block assembly pivoted to its inoperative position away from the slitting blade. The edges of the housing inner side wall 62 and outer side wall 59, defining the open end face 57 of the housing 54 are provided with semicircular recesses 72 to facilitate grasping the lubricant block 55 for insertion into or removal from the housing 54.