Stretch wrapping machine with curve fit control of dispense rate

Patent metadata

Field	Value
Publication number	US-11208225-B2
Application number	US-201916531785-A
Country	US
Kind code	B2
Filing date	Aug 5, 2019
Priority date	Aug 6, 2018
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

A method, apparatus and program product utilize curve fitting to control a dispense rate for a packaging material dispenser. Predicted demands at a plurality of rotational positions of a load relative to a packaging material dispenser may be used to generate one or more points to which a curve may be fit, such that dispense rates may be determined for rotational positions between those for which predicted demands have been determined using the curve.

First claim

What is claimed is:

1. An apparatus for wrapping a load with packaging material, the apparatus comprising:
a packaging material dispenser for dispensing packaging material to the load;
a rotational drive configured to generate relative rotation between the packaging material dispenser and the load about a center of rotation; and
a controller coupled to the packaging material dispenser and the rotational drive and configured to control the packaging material dispenser during the relative rotation to dispense at a first dispense rate at a first rotational position about the center of rotation, wherein the first dispense rate at which the controller controls the packaging material dispenser at the first rotational position is determined using a curve fit between second and third rotational positions that are respectively before and after the first rotational position about the center of rotation and for which predicted demands are determined.

2. The apparatus of claim 1 , wherein the curve is a demand curve defining a demand at each of a plurality of rotational positions between the second and third rotational positions.

3. The apparatus of claim 2 , wherein the first dispense rate is determined by scaling a demand from the demand curve based upon a wrap force parameter.

4. The apparatus of claim 1 , wherein the curve is a dispense rate curve defining a dispense rate at each of a plurality of rotational positions between the second and third rotational positions, wherein the dispense rate at the second rotational position is determined by scaling the predicted demand at the second rotational position by a wrap force parameter, and wherein the dispense rate at the third rotational position is determined by scaling the predicted demand at the third rotational position by the wrap force parameter.

5. The apparatus of claim 1 , wherein the curve includes a portion of a sinusoidal curve fit between the second and third rotational positions.

6. The apparatus of claim 1 , wherein the first dispense rate at the first rotational position is further determined by applying a rotational data shift to offset system lag.

7. The apparatus of claim 6 , wherein the rotational data shift is variable based upon a rotational drive speed.

8. The apparatus of claim 6 , wherein the rotational data shift is applied by rotationally shifting a sensed rotational position of the load.

9. The apparatus of claim 6 , wherein the rotational data shift is applied by rotationally shifting the curve.

10. The apparatus of claim 1 , wherein the predicted demand at the second rotational position is determined based upon a geometric relationship between the packaging material dispenser and a location of a corner of the load within a plane perpendicular to the center of rotation.

11. The apparatus of claim 10 , wherein the predicted demand at the second rotational position is determined based upon a rotation angle about the center of rotation and associated with the corner of the load.

12. The apparatus of claim 11 , wherein the rotation angle is a corner location angle.

13. The apparatus of claim 11 , wherein the rotation angle is a corner contact angle representing an angle at which packaging material first comes into contact with the corner during the relative rotation between the load and the packaging material dispenser.

14. The apparatus of claim 1 , wherein the predicted demand at the second rotational position is determined based upon a sensed tension in a web of packaging material extending between the packaging material dispenser and a corner of the load.

15. The apparatus of claim 1 , wherein the second rotational position is a corner contact angle representing an angle at which packaging material first comes into contact with a corner of the load during the relative rotation between the load and the packaging material dispenser.

16. The apparatus of claim 1 , wherein the second rotational position is a rotational position associated with a local minimum in demand.

17. The apparatus of claim 1 , wherein the second rotational position is a rotational position associated with a local maximum in demand.

18. The apparatus of claim 17 , wherein the second rotational position is a rotational position where a corner radial for a corner of the load forms about a 90 degree angle with a web of packaging material extending between the packaging material dispenser and the corner of the load.

19. The apparatus of claim 1 , wherein the second and third rotational positions are rotational positions respectively before and after the first rotational position about the center of rotation, wherein a fourth rotational position is a corner contact angle, and wherein the curve is fit between the second, third and fourth rotational positions.

20. The apparatus of claim 1 , wherein the second rotational position is a rotational position associated with a local minimum in demand, wherein the third rotational position is a rotational position associated with a local maximum in demand, wherein a fourth rotational position is associated with a rising inflection point having a demand value calculated from an average of the local minimum in demand and the local maximum in demand, and wherein the curve includes a quarter sine curve segment fit between the second, third and fourth rotational positions.

21. The apparatus of claim 1 , wherein the second rotational position is a rotational position associated with a local maximum in demand, wherein the third rotational position is a rotational position associated with a local minimum in demand, wherein a fourth rotational position is associated with a falling inflection point having a demand value calculated from an average of the local maximum in demand and the local minimum in demand, and wherein the curve includes a quarter sine curve segment fit between the second, third and fourth rotational positions.

22. The apparatus of claim 1 , wherein the second rotational position is a corner contact angle for a current corner, wherein the third rotational position is a rotational position associated with a local maximum in demand between the corner contact angle for the current corner and a corner contact angle for a next corner, wherein a fourth rotational position is associated with a rising inflection point having a demand value calculated from an average of the determined predicted demand for the corner contact angle for the current corner and the local maximum in demand, and wherein the curve includes a quarter sine curve segment fit between the second, third and fourth rotational positions.

23. The apparatus of claim 1 , wherein the second rotational position is a rotational position associated with a local maximum in demand, wherein the third rotational position is a corner contact angle for a next corner, wherein a fourth rotational position is associated with a falling inflection point having a demand value calculated from an average of the local maximum in demand and the determined predicted demand for the corner contact angle for the next corner, and wherein the curve includes a quarter sine curve segment fit between the second, third and fourth rotational positions.

24. The apparatus of claim 1 , wherein the curve decreases a rate of change in dispense rate relative to a dispense rate calculated based on predicted demand when the packaging material dispenser is transitioning between acceleration and deceleration.

25. The apparatus of claim

Assignees

• Lantech Com Llc

Inventors

• Mitchell Michael P
• Lancaster Iii Patrick R

Classifications

• B65B11/008

  by webs revolving around articles moved along the axis of revolution · CPC title

• B65B2011/002

  Prestretching mechanism in wrapping machines · CPC title

• B65B2210/20

  the web dispenser being mounted on a rotary arm · CPC title

• B65B57/04 Primary

  and operating to control, or to stop, the feed of such material, containers, or packages · CPC title

• B65B2210/18

  the web dispenser being mounted on a rotary ring · CPC title