Abstract
A bag closing apparatus is provided having a frame, a closure strip guide, a clip separator, and a bag feed conveyor. The frame is configured to carry a strip of closures. The closure strip guide is configured to guide a strip of closures. The clip separator is configured to sever a terminal closure on a strip of closures exiting the strip guide. The bag feed conveyor has a pair of laterally spaced-apart drive wheels and a complementary pair of laterally spaced-apart follower wheels urged into engagement for coaction with the drive wheels to deliver a bag neck into the terminal closure. The drive wheels and the follower wheels each comprise a circumferential outer periphery having a friction-reducing surface having a static dry coefficient of friction of at most 0.2. A method is also provided.
Claims
1. A bag closing apparatus, comprising: a frame configured to carry a strip of closures; a closure strip guide configured to guide a strip of closures; a clip separator configured to sever a terminal closure on a strip of closures exiting the strip guide; and a bag feed conveyor having a pair of laterally spaced-apart drive wheels and a complementary pair of laterally spaced-apart follower wheels urged into engagement for coaction with the drive wheels to deliver a bag neck into the terminal closure, the drive wheels each comprising a circumferential outer periphery having a friction-reducing surface having a static dry coefficient of friction of at most 0.2, and the follower wheels each having a circumferential outer periphery having a friction-reducing surface having a static dry coefficient of friction of at most 0.2.
2. The bag closing apparatus of claim 1, wherein the circumferential outer periphery of each follower wheel comprises a semi-circular cross-sectional groove, and further comprising an O-ring of friction-reducing material.
3. The bag closing apparatus of claim 2, wherein the circumferential outer periphery of each drive wheel comprises a semi-circular cross-sectional groove sized to mate in complementary relation with the O-ring.
4. The bag closing apparatus of claim 1, wherein the circumferential outer periphery of the drive wheels and the follower wheels comprise a friction-reducing layer deposited on the outer periphery of the drive wheels and the follower wheels.
5. The bag closing apparatus of claim 1, wherein the friction reducing surface has a coefficient of friction less than a bag being delivered between the pairs of drive wheels and the follower wheels.
6. The bag closing apparatus of claim 1, wherein the friction reducing surface has a dry contact static coefficient of friction less than or equal to 0.1.
7. The bag closing apparatus of claim 1, wherein the friction reducing surface is a resilient material shaped into an O-ring retained on an outer periphery of each of the follower wheels.
8. The bag closing apparatus of claim 1, wherein the O-ring comprises a polytetrafluoroethylene (PTFE) O-ring seated in a circumferential outer peripheral groove in each of the pair of follower wheels.
9. The bag closing apparatus of claim 1, wherein the friction reducing surface is a polytetrafluoroethylene (PTFE) coating applied to an anodized circumferential outer surface of the drive wheels.
10. A bag feed conveyor for a bag closing apparatus, comprising: a pair of laterally spaced-apart drive wheels each comprising a circumferential outer periphery having a friction-reducing surface having a static dry coefficient of friction of at most 0.2; and a complementary pair of laterally spaced-apart follower wheels urged into engagement for coaction with the drive wheels to deliver a bag neck into the terminal closure each having a circumferential outer periphery having a friction-reducing surface having a static dry coefficient of friction of at most 0.2.
11. The bag feed conveyor of claim 10, wherein each of the follower wheels comprises a circumferential outer periphery having an asymmetric semi-circular cross-sectional groove, and further comprising an O-ring of friction-reducing material carried in the groove.
12. The bag feed conveyor of claim 11, wherein the O-ring comprises polytetrafluoroethylene (PTFE).
13. The bag feed conveyor of claim 12, wherein each of the drive wheels have an outer peripheral portion comprising a polytetrafluoroethylene (PTFE) coating.
14. The bag feed conveyor of claim 13, wherein each of the drive wheels comprises an anodized outer peripheral surface and the PTFE is deposited at least over the anodized outer peripheral surface.
15. The bag feed conveyor of claim 1, wherein the friction reducing surface on the drive wheels and the follower wheels has a static dry coefficient of friction against steel of at most 0.1.
16. The bag feed conveyor of claim 1, wherein the friction reducing surface on the drive wheels and the follower wheels has a static dry coefficient of friction against steel of at most 0.05.
17-20. (canceled)
21. The bag feed conveyor of claim 14, wherein the anodized outer peripheral surface is porous and the PTFE is deposited within the porous surface.
22. The bag feed conveyor of claim 10, wherein pair of drive wheels are substantially parallel to one another and the pair of follower wheels are substantially parallel to one another.
23. The bag feed conveyor of claim 10, wherein the pair of drive wheels and the pair of follower wheels are each provided on a common axis.
24. The bag feed conveyor of claim 23, wherein the common axis for the pair of drive wheels is substantially parallel to the common axis for the pair of follower wheels.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Exemplary embodiments of the various disclosures are described below with reference to the following accompanying drawings. The drawings may be considered to represent scale.
[0008] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.
[0009] FIG. 1 is a perspective view from above and in front of a bag closing apparatus with a bag feed assembly that mitigates any tendency to over-wrap, snag, or clog bags on the bag feed assembly.
[0010] FIG. 2 is a vertical right side view of the bag closing device of FIG. 1.
[0011] FIG. 3 is a front elevational view of the bag closing device of FIG. 2.
[0012] FIG. 4 is an enlarged view of the bag closing device from encircled region 4 of FIG. 3.
[0013] FIG. 5 is a vertical sectional view of the bag closing device taken along line 5-5 of FIG. 4.
[0014] FIG. 6 is an enlarged sectional view of the bag closing device from encircled region 6 of FIG. 5.
[0015] FIG. 7 is a simplified schematic perspective view of the drive assembly of FIGS. 1-6.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0016] This disclosure is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws to promote the progress of science and useful arts (Article 1, Section 8).
[0017] The disclosed device is a special purpose Low Friction Closure Feed Mechanism and Method that allows for reduction and/or elimination of bag overwrap around drive and follower wheels of a bag feed conveyor for a bag closing machine, or apparatus.
[0018] FIG. 1 is a perspective view from above and in front of a bag closing device 10 with a bag feed assembly 36 that mitigates or eliminates any tendency to over-wrap, snag, or clog bags on the wheels of a bag feed assembly, or conveyor 36. Bag closing apparatus 10 includes an upper housing assembly, or frame 12, a lower housing assembly, or frame 14, a reel assembly 16 and a vertical structural support post 18 supporting reel assembly 16 atop upper housing assembly 12. A pair of bag closure reels 20 and 22 are provided on reel assembly 16.
[0019] As shown in FIG. 1, a closure strip guide assembly 24 guides and delivers a strip 30 of closures 32 through an expansible guide assembly 26 having a pivotal door 28 for individual, sequential application onto bag necks (not shown). Bag feed conveyor 36 in concert delivers bunched individual bag necks into an individual lowest closure 32 of a continuous strip 30 of closures, or clips 32 with a reduced tendency to jam. Bag feed conveyor 36 is carried by housing, or frame 34 and comprises a drive motor 38 and contact drive mechanisms that have reduced friction components shown to mitigate bag wrap-around or jamming about convenor 36 during operation.
[0020] FIG. 2 is a vertical right side view of the bag closing device 10 of FIG. 1. A strip of closures 30 are delivered downwardly through a bag feed conveyor 36 depending from upper housing assembly 12. Upper housing assembly 12 and lower housing assembly 14 are supported in spaced apart relation by a housing, or frame 34. Bag feed conveyor 36 comprises an upper follower wheel bag conveyor assembly 40 and a lower drive wheel bag conveyor assembly 42. Upper follower wheel bag conveyor assembly 40 and lower drive wheel bag conveyor assembly 42 receive individual bag necks in between and have friction-reducing contact portions that engage with bag necks in order to reduce or eliminate a known problem with bag necks wrapping around follower wheels and/or drive wheels.
[0021] FIG. 3 is a front elevational view of the bag closing device 10 of FIG. 2. Strip 30 of closures, or clips enter upper housing assembly of frame 34 for individual, incremental delivery to a bag feed conveyor 36 where a bag is fed into an individual closure delivered between upper follower wheel conveyor assembly 40 on upper housing assembly 12 and lower drive wheel conveyor assembly 42 on lower housing assembly 14.
[0022] FIG. 4 is an enlarged view of the bag closing device 10 from encircled region 4 of FIG. 3. Components of bag feed conveyor 36 are shown between upper follower wheel conveyor assembly 40 on upper housing assembly 12 and lower drive wheel conveyor assembly 42 on lower housing assembly 14. More particularly, upper follower wheel conveyor assembly 40 includes a pivotally sprung follower wheel arm assembly 52 having a pair of laterally spaced apart pivot arms 54 and 56 carried by a pivot bolt 70 each having a follower wheel 44 and 46 at a distal end and a coil spring 64 and 66 at a proximal end configured to urge each wheel into independent engagement with a split drive wheel 48. Each wheel 44 and 46 is carried by a cylindrical bearing assembly 60 and 62 for rotation on respective arm 54 and 56. Strip 30 of closures 32 are incrementally fed downwardly via closure strip guide assembly 24, affixed to frame 76, where individual closures are loaded with a bag neck by bag feed conveyor 36 and severed with a closure separating apparatus, or cutter 80.
[0023] As shown in FIG. 4, a split, or dual drive wheel member 48 is carried for rotation by a cylindrical bearing assembly 58 on frame 74. A drive chain 78 of a chain drive assembly 50 drives dual drive wheel member 48 via a sprocket 96 (see FIG. 6) while a clutched drive sprocket 82 engages chain 78 in response to a trigger (not shown) that engages the clutch on sprocket 82 to drive wheel member 48 intermittently as needed. A bag neck is passed between wheels 44, 46 and dual drive wheel member 48 for delivery into a closure 32.
[0024] FIG. 5 is a vertical sectional view of the bag closing device 10 taken along line 5-5 of FIG. 4 showing a strip 40 of closures delivered incrementally between an upper follower wheel conveyor assembly 40 of upper housing assembly 12 and a lower drive wheel conveyor assembly 42 of lower housing assembly 14. Upper housing assembly 12 and lower housing assembly 14 are carried by a common housing, or frame 34.
[0025] FIG. 6 is an enlarged sectional view of the bag closing device 10 from encircled region 6 of FIG. 5. More particularly, upper follower wheel conveyor assembly 40 is urged downwardly under spring tension into lower drive wheel conveyor assembly 42 and friction reducing materials are used in order to minimize or eliminate gripping and wrap-around of individual bag necks as they are conveyed into individual closures 32 of strip 30. Upper follower wheel conveyor assembly 40 comprises a pair of anodized aluminum wheels 44 and 46 each having an outer peripheral asymmetric semicylindrical groove 106 and 108 that receives a polytetrafluoroethylene (PTFE) o-ring. Each groove 106 and 108 has a reduced diameter inner flange sized to facilitate loading of each O-ring 106 and 108 onto respective follower wheel 44 and 46 on an inboard side where such O-ring is them trapped in assembly and unlikely to jump off of each respective wheel 44 and 46. Lower drive wheel conveyor assembly 42 comprises a unitary split drive wheel member 48 comprising a pair of integrally formed drive wheels 98 and 100 spaced apart to mate with respective follower wheels 44 and 46. An outer peripheral semi-cylindrical groove 102 and 104 in each drive wheel 98 and 100 is sized to receive each o-ring 90 and 92 on respective follower wheels 44 and 46. Split drive wheel member 48, including drive wheels 98 and 100 are formed from anodized aluminum and a PTFE coating is deposited at least on a top surface and potentially within pores in the anodized aluminum outer layer.
[0026] As shown in FIG. 6, split drive wheel 48 is carried for driven rotation on a drive hub 58 via a chain drive sprocket 96 affixed onto hub 58 and driven by a drive chain 78. Drive hub 58 is supported for rotation in a cylindrical bearing 94. O-rings 90 and 92 and drive wheels 98 and 100 comprise friction reducing materials and/or surfaces. Chain 78 is driven by a drive sprocket on a drive motor 38 (see FIG. 1). Clutch sprocket 82 (see FIG. 4) intermittently drives chain 78 in response to a trigger (not shown) that engages the clutch sprocket 82 and chain 78 in response to the trigger detecting a bag loading into a closure.
[0027] FIG. 7 is a simplified schematic perspective view of a generic drive assembly similar to bag feed conveyor 36 used in FIGS. 1-6. Follower wheels 244 and 246 are supported in engagement with drive wheels 298 and 300 of split drive wheel 48 where a bag neck is delivered between respective wheels 244, 298 and 246, 300. It has been a longstanding recognized problem that bag necks can wrap around follower wheels 244 and 246, as well as drive wheels 298 and 300, causing a bag closing machine to shut down, and requiring maintenance, and/or repair. For years, customers and users have complained about bag overwrap around such drive and follower wheels. The component surfaces and/or materials that contact a bag delivered between these pairs of wheels 244, 246 and 298, 300 (as well as the wheels of bag feed conveyor 36 (of FIGS. 1-6)) each comprise a reduced, or low friction material, such as a polytetrafluoroethylene (PTFE), a ceramic material or coating, a combination anodized aluminum having impregnated and/or coated low friction coating, such as PTFE, or other suitable low friction material. Testing has shown materials having a static coefficient of friction of 0.15 or lower provide reduced or eliminated wrap-around with such wheels when applying closures to bags. In some cases, the static coefficient is similar or substantially equal to the dynamic coefficient of friction between contact surfaces including a bag, such as a polyethylene bag. Suitable low friction materials or coatings include PTFE, polyoxymethylene (POM), Delrin, Acetal, ceramic, diamond-like carbon (DLC), CrC multi-layered diamond like coating (CrC-DLC), silicon doped carbon like films (Si-DLC), Cr doped diamond like carbon (Cr-DLC), Ti doped diamond like carbon (Ti-DLC), tungsten carbide carbon layer (WC/C), TiAIN-WC/C, as well as other nano-layered low friction coatings and hard ceramic coatings.
[0028] PTFE has a static dry coefficient of friction against steel of 0.01. DLC (PVD) coatings have a static dry coefficient of friction against steel of 0.1. Composite film coatings have a static dry coefficient of friction against steel of 0.14. Diamond has a static dry coefficient of friction against steel of 0.1. Polyethylene has a static dry coefficient of friction against steel of 0.2. It has been discovered that PTFE virtually eliminates any wrap-around of polyethylene bread bags from around the wheels of bag feed conveyor 36 (wheels 244, 246 and 298, 300; as well as wheels 44, 46 and 98, 100 (see FIG. 6)). As used herein, low coefficient of friction refers to a static dry coefficient of friction against steel of at most 0.2, and preferably to at most 0.1, but a coefficient of 0.04 for PTFE has been identified as practically eliminating most if not all wrap-around jams of a polyethylene bag about such wheels.
[0029] As shown herein, PTFE O-rings 90 and 92 on follower wheels 44 and 46 are shown with a cylindrical cross-section. However, it is understood that other ring cross sections can be used including square, rectangular, belt shaped, octagonal, or any other suitable elastic ring-shaped low friction material suitable to engage with a bag, such as a polyethylene bag to load such bag neck into a closure. Further optionally, any suitable low friction material or coating (as recited herein) can be used with the follower wheels, as well as the drive wheels.
[0030] The terms a, an, and the as used in the claims herein are used in conformance with long-standing claim drafting practice and not in a limiting way. Unless specifically set forth herein, the terms a, an, and the are not limited to one of such elements, but instead mean at least one.
[0031] In compliance with the statute, the subject matter disclosed herein has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the claims are not limited to the specific features shown and described, since the means herein disclosed comprise example embodiments. The claims are thus to be afforded full scope as literally worded, and to be appropriately interpreted in accordance with the doctrine of equivalents.
