Fly-knife dampening system

• US 5,176,610 A
• Filed: 05/13/1991
• Issued: 01/05/1993
• Est. Priority Date: 05/13/1991
• Status: Expired due to Fees

• Current Assignee: CMD Corporation
• Original Assignee: Custom Machinery Design, Inc.
• Inventors: Gietman, Peter J. Jr.
• Primary Examiner(s): Watts, Douglas D.
• Assistant Examiner(s): Jones, Eugenia A.
• Application Number:
  US07/699,163
• Time in Patent Office: 603 Days
• Field of Search: 83/349, 83/331, 83/337, 83/343, 83/344, 83/345, 83/346, 83/348, 83/564, 83/673, 83/674, 83/678, 83/695, 493/194, 493/195, 493/196, 493/197, 493/199, 493/200, 493/201, 493/202, 493/233, 242/56 R
• US Class Current: 493/194
• CPC Class Codes: B26D 1/626 for thin material, e.g. for sheets, strips or the like
• CPC Class Codes: B26D 7/08 Means for treating work or cutting member to facilitate cutting tensioning band cutters B26D1/48
• CPC Class Codes: Y10T 83/4812 Compound movement of tool during tool cycle
• CPC Class Codes: Y10T 83/4847 With cooperating stationary tool
• CPC Class Codes: Y10T 83/8749 By pivotal motion

Abstract

A system for dampening deflections which occur in an elongate rotating fly-knife includes camming elements along the length of the beam carrying the fly-knife. A second beam spaced from the knife is also mounted for rotation and includes spaced apart camming elements adapted to rotate and contact the fly-knife camming elements at that point during the rotational cycle when the fly-knife will cut and/or perforate the material with which the apparatus of the present invention is employed. In one preferred embodiment of the invention, the system is used to perforate, slit or cut plastic film, e.g., in the manufacture of bags. In another preferred embodiment of the invention, the system is used with a coversheet winding machine. The rotating beams of the invention are preferably driven by a single motor to maintain registration of the knife camming elements with the support beam camming elements.

Claims

1. A fly-knife dampening system, comprising:

an elongate bed knife which is stationary during use of the system and having a bed knife blade;

an elongate rotating fly-knife having a fly-knife blade and plural and spaced apart cams disposed thereon, said fly-knife being rotatable about an axis such that at a predetermined time during such rotation, said fly-knife blade operatively engages said bed knife blade; and

a rotating support shaft parallel to, but spaced apart from said rotating fly-knife, said support shaft having plural and spaced apart support cams mounted thereon for rotation therewith, said support cams disposed such that each time said fly-knife blade operatively engages said bed knife blade, said support cams engage said fly-knife cams.

2. The fly-knife dampening system of claim 1, wherein said fly-knife cams have an arcuate edge, and said support cams have an arcuate edge, said arcuate edges of said fly-knife cams being designed to roll against said arcuate edges of said support cams.

3. The fly-knife dampening system of claim 2, further comprising means for controlling the rotation of said support shaft and said rotating fly-knife such that said support cams and said fly-knife cams rotate at the same speed.

4. The fly-knife dampening system of claim 2, wherein two support cams contact two fly-knife cams.

5. A system for use in machine for making bags from a polymeric film, said system comprising:

an elongate bed knife having a bed knife blade, said bed knife being stationary during use of the system;

an elongate rotating fly-knife having a fly-knife blade and plural and spaced apart fly-knife cams disposed thereon, said fly-knife blade being operatively engageable with said bed knife to perform operations on the film;

an elongate rotating support shaft having plural and spaced apart support cams mounted thereon, said support cams disposed such that contact is made between said support cams and fly-knife cams each time said fly-knife blade operatively engages said bed knife; and

wherein said bed knife is mounted for rotational movement away from said fly-knife, whereby the film can pass through the juncture of said fly-knife and said bed knife without having operations performed thereon when the system is not in use.

6. In a machine for making plastic bags from plastic film moving along a film path of the type comprising a drum-shaped rotatable sealing means for sealing said film, blanket means surrounding a portion of said sealing means and rotatably driving said sealing means, folding means located along said path, and knife means along said path for selectively cutting and perforating said film to form interconnected bags, the improvement wherein:

said knife means comprises;

an elongate bed knife which is stationary during use of the system and including a bed knife blade;

an elongate rotating fly-knife including a fly-knife blade rotatable about a longitudinal axis and having plural and spaced apart cams disposed thereon, said fly-knife

blade being operatively engagable with said bed knife blade at a predetermined time during rotation of the fly-knife; and

a rotating support shaft parallel to, but spaced apart from said rotating fly-knife, said support shaft having plural and spaced apart support cams mounted thereon for rotation therewith, said support cams disposed such that each time said fly-knife blade operatively engages said bed-knife blade, said support cams engage said fly-knife cams.

7. The machine of claim 6, further comprises:

a drive system for operatively driving said fly-knife and said support shaft such that said support cams operatively contacts said fly-knife cams as said fly-knife blade operatively engages said bed knife blade.

8. The machine of claim 7, wherein said fly-knife cams have an arcuate edge.

9. The machine of claim 7, wherein support cam has an arcuate edge.

10. The machine of claim 7, wherein two support cams contact two fly-knife cams.

11. A system for use in a winder for winding elongate strips of pliable material, such as plastic film, cloth or paper, into coreless rolls, said system comprising:

an elongate bed knife which is stationary during use of the system having a bed knife blade;

an elongate rotating fly-knife having a fly-knife blade and plural and spaces apart cams disposed thereon, said fly-knife blade being operatively engagable with said bed knife blade to sever said pliable material;

a rotating support shaft parallel to, but spaced apart from said rotating fly-knife, said support shaft having plural and spaced apart cams mounted thereon for rotation therewith;

wherein said support cams are disposed such that contact is made between said support cams and said fly-knife cams when said fly-knife blade operatively engages said bed knife blade to sever said pliable material.

12. The system of claim 11, wherein said bed knife is movable into a cutting position in which said fly-knife is operatively engagable with said bed knife and said support cams are operatively engagable with said fly-knife cams.

13. The system of claim 12, further comprising drive means for operatively driving said fly-knife cams and said support cams such that said support cams and said fly-knife cams rotate at substantially the same speed.