Abstract
An end seal for removable attachment to a doctor blade assembly is provided. The end seal comprises a seal body having a bottom wall, opposite first and second sidewalls and a top edge configured to include a radius adapted to seal against a roller surface. At least one abrasion resistant insert is integrally secured within the seal body. The insert includes a bottom wall, opposite first and second sidewalls and a top edge configured to coincide with the body top edge so as to seal against the roller surface. The seal body and the at least one abrasion resistant insert each further comprise respective first and second upper angled sidewalls extending from respective opposite first and second sidewalls, the respective first upper angled sidewall having a different length and tapering from the top edges at a different angle than the respective second upper angled sidewall.
Claims
1. An end seal for removable attachment to a doctor blade assembly having first and second doctor blades configured to engage a roller surface, the end seal comprising: a seal body having a bottom wall and opposite first and second sidewalls and a top edge configured to include a radius adapted to align with and seal against the roller surface; at least one abrasion resistant insert secured within said seal body, said at least one abrasion resistant insert including a bottom wall and opposite first and second sidewalls and an insert top edge configured to coincide with said seal body top edge to align with and seal against a roller surface, wherein said seal body and said at least one abrasion resistant insert each further comprise respective first and second upper angled sidewalls extending from respective said opposite first and second sidewalls, said respective first upper angled sidewall having a different length and tapering from said seal body and insert top edges at a different angle than said respective second upper angled sidewall.
2. The seal of claim 1 wherein said at least one abrasion resistant insert includes one or more holes wherein said seal body impregnates said holes.
3. The seal of claim 1 wherein one or both of said opposite first and second insert sidewalls resides within and is encapsulated by said seal body.
4. The seal of claim 1 wherein said insert bottom wall resides within and is encapsulated by said seal body.
5. The seal of claim 1 wherein said abrasion resistant insert has a thickness (T) thinner than a width (W) of said seal body wherein said abrasion resistant insert is centrally located within said seal body.
6. The seal of claim 1 wherein said abrasion resistant insert is constructed of a material selected from the group consisting of polytetrafluoroethylene, polyoxymethylene, ultra-high-molecular-weight polyethylene, biaxially-oriented polyethylene terephthalate, a perfluoroalkoxy alkane, fluorinated ethylene propylene and combinations thereof.
7. The seal of claim 1 and further comprising first and second abrasion resistant inserts secured in spaced, parallel relation to each other within said seal body.
Description
BRIEF DESCRIPTION OF THE DRAWING
(1) FIG. 1 is an enlarged perspective view of an embodiment of the inventive end seal;
(2) FIG. 2 is an exploded view of the end seal shown in FIG. 1;
(3) FIG. 3 is a cross-section view as taken generally along the line 3-3 in FIG. 1;
(4) FIG. 4 is an exemplary end perspective view of the relation between the end seal shown in FIG. 1 and a corresponding roller;
(5) FIGS. 5A-C are two perspective views and a side elevational view, respectively, of another embodiment of seal;
(6) FIGS. 6A and 6B are perspective and side elevational views, respectively, of yet another embodiment of end seal; and
(7) FIGS. 7A and 7B are perspective and side elevational views, respectively, of still another embodiment of end seal.
DETAILED DESCRIPTION
(8) Referring now to the drawing, there is seen in FIGS. 1-4 an embodiment of the inventive end seal designated generally by the reference numeral 10. Seal 10 includes a seal body 20 adapted to carry an integral abrasion resistant insert 30. Seal body 20 is preferably formed from a from a rigid yet resilient material (e.g., about 25-90 Durometer Shore A, more preferably about 60-80 Shore A, and yet more preferably about 70 Shore A) which may be injection or compression molded from an appropriate material such as, for example, thermoplastic materials or thermoset materials, EPDM rubber, Buna-N rubber, Natural Rubber, SBR Rubber, Viton, of a rubber compound that has been blended with performance enhancing additives having like characteristics, although other manufacturing processes are of course possible (e.g., cast molding, machining, SLA, vulcanization, vacuum molding, rapid prototyping, mechanical die cutting, water jet cutting, etc.). For the sake of simplicity, the material comprising body 20 will hereinafter be referred to as rubber, although it is understood that any suitable material may be used as described above. Resident within seal body 20 is an insert 30. Insert 30 is preferably formed from an abrasion resistant material such as Teflon (polytetrafluoroethylenePTFE), a perfluoroalkoxy alkane (PFA), fluorinated ethylene propylene (FEP), strip steel, biaxially-oriented polyethylene terephthalate (BoPET) (such as that sold under the trade name Mylar), UHMWPE, POM (acetal) or other like materials. Again, for sake of simplicity, the material constructing insert 30 will be referred to as Teflon although it is understood that any alternative suitable material may be used.
(9) In the presently preferred embodiment of an injection molded seal, as seen in FIGS. 1-4, abrasion resistant insert 30 is integrally formed within body 20. Insert 30 may include one or more holes 32 passing therethrough. Holes 32 allow the rubber material constituting body 20 to flow through the holes during manufacture thereby impregnating the holes 32 with rubber. The rubber impregnated holes ensure that the insert is positioned and anchored correctly within the seal 10. As a result, insert 30 is an integral and permanent component of the completed seal 10. The insert 30 will not lose its position within body 20, nor will it become dislodged or delaminated from the body 20 during operational rotation of the roller 50 (FIG. 4). The rubber material of body 20 residing with holes 32 of insert 30 further creates a suspension system for the insert. That is, the rubber body 20 provides the necessary compression/recovery properties that allow the abrasion resistant insert 30 to flex or otherwise absorb the mechanical tolerances inherent within the printing machine once the seal 10 is engaged against the rotating anilox roller 50 under pressure.
(10) As seen best in FIG. 3, with combined reference to FIG. 2, seal body 20 is dimensioned to have a body width W and includes opposite body end walls 24b and 24c each having wall heights H.sub.B and a body bottom wall 24d defining a total body length L.sub.B. The upper surface of seal body 20 includes a top radius edge 24a situated between opposite angled upper sidewalls 24a and 24a. Upper sidewalls 24a and 24a each taper inwardly as they extend toward the center of seal 10 and are adapted to carry optional doctor blades (not shown) as is generally known in the art. Similarly, insert 30 is dimensioned to have an insert thickness T and includes opposite insert end walls 34b and 34c each having wall heights H.sub.I and an insert bottom wall 34d defining a total insert length L.sub.I. The upper surface of insert 30 includes a top radius edge 34a situated between opposite angled upper sidewalls 34a and 34a. Again, upper sidewalls 34a and 34a each taper inwardly as they extend toward the center of seal 10 and are adapted to carry optional doctor blades.
(11) As seen in FIGS. 1, 3 and 4, insert 30 is positioned within body 20 such that top radius edge 34a of insert 30 is present at the radius edge 24a of body 20. As shown generally in FIG. 4, the combined top radius edges 24a and 34a are configured to be in intimate contact with rotating cylinder/roller 50. The thin surface of top radius edge 34a of insert 30 (as denoted by thickness T in FIG. 2) may act as a rotary doctor blade while the rubber portions of body radius edge 24a contact the rotating cylinder 50 on either side of insert 30 so as to provide two sealing surfaces to hold the ink/fluids within the enclosed chamber defined by opposing seals 10 in a fully assembled doctor blade assembly. The Teflon material of the abrasion resistant insert 30 wears more slowly than the rubber material constituting the remainder of end seal 10. In this manner, the frictional wear subjected to rubber body radius edge 24a is mitigated by insert top radius edge 34a of the abrasion resistant insert 30. This arrangement prolongs the operational lifetime of seal 10 while maintaining adequate liquid seals against rotating cylinder/roller 50.
(12) With continued reference to FIG. 3, insert 30 has an insert length L.sub.I which is less than body length L.sub.B such that one or neither of insert sidewalls 34b or 34c is configured to coincide with body edge sidewalls 24b or 24c. In this manner, one or both of the insert sidewalls 34b/34c may be resident within and encapsulated by the rubber material comprising seal body 20. Similarly, insert 30 may have a sidewall height H.sub.I smaller than body height H.sub.B such that insert bottom wall 34d does not coincide with body bottom wall 24d but is terminated within and encapsulated by the rubber material comprising seal body 20. The encapsulation of either or both of the insert sidewalls 34b/34c and/or the insert bottom wall 34d provides compression/recovery properties that allow the abrasion resistant insert 30 to flex or otherwise absorb the mechanical tolerances inherent within the printing machine once the seal 10 is engaged against the rotating roller 50.
(13) FIGS. 5A-5C show another embodiment of a seal body 60 having first and second abrasion resistant inserts 62, 64 positioned in spaced, parallel relation to each other at the top radius edge 60a situated between opposite angled upper sidewalls 60a and 60a (see FIG. 5C). The seal body upper sidewalls 60a and 60 are dimensioned as needed to properly engage the relative positioning and geometry of the particular doctor blades used (not shown) which may or may not result in a symmetrical end seal. In the asymmetrical example of seal body 60, upper side walls 60a and 60a are shown to be of slightly different lengths with each tapering at a different angle a and b as they extend toward the center of seal 60, respectively (see FIG. 5A).
(14) First and second inserts 62, 64 are either integrally molded into seal body 60 as explained above, or may be dimensioned to fit snugly within a cooperatively sized respective groove 66 and 68 machined or otherwise formed into seal body 60 (see FIG. 5B). Inserts 62, 64 may optionally be further secured in respective grooves 66, 68 using an adhesive or ultrasonic welding, for example.
(15) As seen in FIG. 5C, first and second inserts 62, 64 are positioned within seal body 60 in the same manner as seal body 20 and insert 30, i.e., the exposed top radius edges 62, 64 of inserts 62, 64 are present at and preferably substantially flush with the radius edge surface 60a of body 60. If required for the particular application, inserts 62 and 64 may extend past radius edge surface 60a and into one or both of upper side walls 60a and 60a as shown.
(16) FIGS. 6A and 6B show another single insert embodiment having an asymmetrical seal body 70 and insert 72 having opposite ends 72a, 72b which are spaced from respective seal body end walls 70a and 70b.
(17) FIGS. 7A and 7B show yet another single insert embodiment having an asymmetrical seal body 80 and insert 82 having a thickness 82a which is larger than the inserts of the other embodiments. Insert 82a may be made from a fabric type material such as felt, for example, although it is understood that the inserts may be made of any desired synthetic or natural material and be of any number, thickness or length as appropriate for the particular machine application.
(18) Although the invention has been described with reference to preferred embodiments thereof, it is understood that various modifications may be made thereto without departing from the full spirit and scope of the invention as defined by the claims which follow.
