Tensioning apparatus and methods for plastic packaging

• US 4,723,390 A
• Filed: 08/11/1986
• Issued: 02/09/1988
• Est. Priority Date: 08/11/1986
• Status: Expired due to Fees

• Current Assignee: Horace W. Duke
• Original Assignee: Horace W. Duke
• Inventors: Duke, Horace W.
• Primary Examiner(s): Coan, James F.
• Application Number:
  US06/895,141
• Time in Patent Office: 547 Days
• Field of Search: 53/372, 53/371, 53/373, 53/138 A, 493/406
• US Class Current: 53/373.4
• CPC Class Codes: B65B 7/06 by collapsing mouth portion, e.g. to form a single flap

Abstract

A method and apparatus for tensioning or drawing taut a plastic bag or packaging around a product prior to sealing is disclosed. The apparatus operates in combination with presently available conveying means and packaging sealing means. The apparatus includes a housing to support and contain a pair of conical brushes having rotational axes parallel to the direction of travel of the conveyor belt. The conical brushes rotate in opposite directions so as to draw excess packaging material into the nip formed by the tip of the brushes to smooth away wrinkles and/or folds. A transport and gripping belt then closes the bag and moves it past a pair of cylindrical shaped brushes which may be on the same shaft as the conical brushes. The cylindrical brushes draw the packaging material tight or taut around the product in a manner suitable for sealing. Drive motors for the transport belt and the rotating brushes include means for varying the respective speeds such that various products and packaging materials can be handled.

Claims

1. Apparatus for sealing plastic packaging material taut around a product comprising:

conveying means for moving along a predetermined path and having a first and further side, and for carrying a product contained by plastic packaging material having an open end with excess material at said open end, said package oriented on said conveying means such that said excess material extends beyond said further side and transverse to said predetermined path;

a support structure or housing located proximate said further side of said conveying means, and prior to a sealing and trimming means also located along said predetermined path;

guide means adjacent said support structure for gathering said excess plastic packaging material as said package is carried toward said support structure and guiding said material toward an entry point on said support structure;

means extending between said support structure and said sealing and trimming means for gripping said excess plastic material, and at least partially closing said packaging material around said product, and for moving said open end of said packaging material through said support structure and said sealing and trimming means;

a pair of substantially cylindrical shaped brushes contained and supported by said support structure and each rotatable around their longitudinal axis, said longitudinal axis of each of said pair being substantially parallel to said predetermined path, and the tips of the bristles of one of said pair being at least substantially in contact with the tips of the bristles of the other one of said pair, said brushes rotating in opposite directions such that the excess plastic material at the open end of the package is drawn into the nip between the brushes so as to pull the plastic material taut around the product therein;

a pair of conical shaped brushes supported and contained by said support structure and located along said predetermined path ahead of said pair of cylindrical shaped brushes, the longitudinal axes of said conical shaped brushes substantially parallel to said predetermined path, the apex of said conical shaped brushes being toward said entry point and the base of said conical shaped brushes being toward said cylindrical brushes, said tips of the bristles at the base of said brushes being substantially in contact, said conical brushes operating to smooth wrinkles and folds out of said excess plastic material at the open end of said packaging material prior to said packaging material being drawn into the nip of said cylindrical brushes;

means for rotating said cylindrical and said conical shaped brushes; and

sealing and trimming means located proximate said further side of said conveying means for sealing said open end of said plastic packaging material drawn taut by said brushes and trimming said excess material.

3. The apparatus of claims 1 or 2 and further including means for adjusting the speed said gripping means moves said packaging material past said cylindrical brushes.

4. The apparatus of claims 1 or 2 and further including means for selectively adjusting the spacing between the tips of the bristles of said cylindrical brushes between a first position wherein the tips are separated by about one sixteenth (1/16) inch, and a second position wherein the tips of the bristles overlap by about three sixteenth (3/16) inch.

5. The apparatus of claims 1 or 2 and further including means for selectively adjusting the spacing between the parallel axes of said conical brushes such that the tips of the bristles at the base of the conical shape are separated by a distance of about one sixteenth (1/16) inch at a first position and overlap by about three sixteenth (3/16) inch at a second position.

6. The apparatus of claims 1 or 2 wherein said means for rotating said cylindrical and said conical shaped brushes is the same means.

7. The apparatus of claim 1 or 2 and further including means for adjusting the rotational speed of said cylindrical brushes.

8. The apparatus of claims 1 or 2 and further including means for adjusting the speed said gripping means moves said packaging material through said cylindrical brushes.

9. The apparatus of claim 7 and further including means for adjusting the speed said gripping means moves said packaging material through said cylindrical brushes.

10. The apparatus of claims 1 or 2 and further including means for adjusting the rotational speed of said cylindrical brushes and said conical brushes.

11. The apparatus of claim 9 wherein said rotational speed and said speed of said gripping means are adjusted such that the ratio of the bristle tip speed of the cylindrical brushes to the speed of the gripping means moving the packaging material is a minimum of 5:

1.

12. The apparatus of claim 10 and further including means for adjusting the speed said gripping means moves said packaging material through said cylindrical brushes.

13. The apparatus of claim 10 wherein said rotational speed of said cylindrical brushes is selected such that the speed of the tips of said bristles is between about 980 and 1950 feet per minute.

14. The apparatus of claim 8 wherein said gripping means moves said packaging material through said cylindrical brushes at a speed of between about 20 and 110 feet per minute.

2. Apparatus operating in combination with means for sealing the open end of plastic packaging around a product and a conveying means to carry said packaging along a predetermined path, said apparatus located at the side of said conveying means and comprising:

a support structure

guide means adjacent said housing for gathering excess plastic packaging material at said open end of said package as said conveying means carries said package toward said apparatus, and guiding said material toward an entry point of said apparatus;

means for gripping said excess plastic material, and at least partially closing said packaging material around said product, and for moving said open end of said packaging material through said apparatus;

a pair of cylindrical shaped brushes contained and supported by said support structure and rotatable around their longitudinal axis, said longitudinal axis of each of said pair being substantially parallel to said predetermined path and the tips of the bristles of one of said pair substantially in contact with the tips of the bristles of the other one of said pair, said brushes rotating in opposite directions such that the excess plastic material at the open end of the package is drawn into the nip between the brushes so as to pull the plastic material taut around the product therein prior to sealing said open end;

a pair of conical shaped brushes supported and contained by said support structure and located along said predetermined path ahead of said pair of cylindrical shaped brushes, the longitudinal axes of said conical shaped brushes substantially parallel to said predetermined path, the apex of said conical shaped brushes being toward said entry point and the base of said conical shaped brushes being toward said cylindrical brushes, said tips of the bristles at the base of said brushes being substantially in contact, said conical brushes operating to smooth wrinkles and folds out of said excess plastic material at the open end of said packaging material prior to said packaging material being drawn into the nip of said cylindrical brushes; and

means for rotating said cylindrical and said conical shaped brushes.