Wrapping apparatus including metered pre-stitch film delivery assembly and method of using

An apparatus for stretch wrapping a load, comprising:

• a packaging material dispenser for dispensing packaging material, the packaging material dispenser including a pre-stretch assembly;
• a drive mechanism configured to provide relative rotation between the packaging material dispenser and the load;
• a variable mechanical connection operatively coupling the drive mechanism and the pre-stretch assembly, the variable mechanical connection being configured to implement a ratio of relative rotation speed to pre-stretch speed during at least a primary portion of a wrapping cycle;
• and
• a sensing element configured to sense a characteristic of the pre-stretched packaging material, a setting of the variable mechanical connection being adjusted in response to a change in the sensed characteristic.

An apparatus for stretch wrapping a load, comprising:

• a packaging material dispenser for dispensing packaging material, the packaging material dispenser including at least one packaging material dispensing roller;
• a drive mechanism configured to provide relative rotation between the packaging material dispenser and the load;
• a variable mechanical connection operatively coupling the drive mechanism and the packaging material dispensing roller, the variable mechanical connection being configured to implement a ratio of relative rotation speed to packaging material dispensing roller speed, an output of the variable mechanical connection driving the packaging material dispensing roller to dispense a selected length of packaging material for at least a portion of a relative revolution between the packaging material dispenser and the load;
• and
• a sensing element configured to sense a characteristic of the pre-stretched packaging material, a setting of the variable mechanical connection being adjustable based at least in part on the sensed characteristic.

A method for stretch wrapping a load, comprising:

• dispensing packaging material with a packaging material dispenser;
• providing relative rotation between the packaging material dispenser and the load with a drive mechanism;
• setting a ratio of relative rotational speed to packaging material dispensing speed with a variable mechanical connection operatively coupling the drive mechanism to the packaging material dispenser;
• sensing a characteristic of the dispensed packaging material with a sensing element;
• and
• adjusting a setting of the variable mechanical connection based at least in part on the sensed characteristic.

A method for stretch wrapping a load, comprising:

• establishing a length of packaging material to be dispensed for at least a portion of a revolution of a packaging material dispenser relative to the load;
• providing relative rotation between the packaging material dispenser and the load with a rotational drive;
• setting a ratio of relative rotational speed to packaging material dispensing speed with a variable mechanical connection operatively coupling the packaging material dispenser and the rotational drive;
• driving the dispensing of packaging material at the set ratio to dispense the length of packaging material during the portion of the revolution of the packaging material dispenser relative to the load;
• sensing a characteristic of the dispensed packaging material with a sensing element;
• and
• responding to a change in the sensed characteristic by adjusting a setting of the variable mechanical connection.

A method for stretch wrapping a load with a wrapping apparatus including a packaging material dispenser having a pre-stretch portion, the method comprising:

• providing relative rotation between the packaging material dispenser and the load with a rotational drive mechanism;
• setting a ratio of relative rotational speed to pre-stretch speed with a variable mechanical connection operatively coupling the rotational drive mechanism to the pre-stretch portion;
• driving the pre-stretch assembly with an output of the variable mechanical connection to dispense a substantially constant length of pre-stretched packaging material during at least a portion of a relative rotation between the load and the packaging material dispenser;
• sensing a characteristic of the dispensed pre-stretched packaging material with a sensing element, and adjusting a setting of the variable mechanical connection based at least in part on sensing a change in the characteristic;
• and
• roping a portion of the packaging material as the packaging material dispenser moves vertically with respect to the load so as to wrap the roped portion of packaging material spirally around the load.

An apparatus for stretch wrapping a load, comprising:

• a packaging material dispenser for dispensing packaging material, the packaging material dispenser including at least one packaging material dispensing roller;
• a drive mechanism configured to provide relative rotation between the packaging material dispenser and the load;
• a variable mechanical connection operatively coupling the drive mechanism to the at least one packaging material dispensing roller, the variable mechanical connection being configured to set a ratio of relative rotation speed to packaging material dispensing roller speed, the variable mechanical connection including
• an input operatively coupled to the drive mechanism to receive power from the drive mechanism, and
• an output operatively coupled to the at least one packaging material dispensing roller, the output being configured to receive power from the input to drive the packaging material dispensing roller to dispense a selected length of packaging material for at least a portion of a relative revolution between the packaging material dispenser and the load;
• and
• a sensing element configured to sense a characteristic of the pre-stretched packaging material, a setting of the variable mechanical connection being adjustable based at least in part on a change in the sensed characteristic.

A method for stretch wrapping a load, comprising:

• dispensing packaging material with a packaging material dispenser;
• providing relative rotation between the packaging material dispenser and the load with a relative rotation drive mechanism;
• setting a ratio of rotational speed to packaging material dispensing speed with a hydrostatic transmission operatively coupling the rotational drive mechanism to the packaging material dispenser;
• and
• selectively adjusting the ratio in response to a change in tension in the packaging material sensed by a sensing element operatively coupled to the hydrostatic transmission.

A method for stretch wrapping a load, comprising:

• dispensing packaging material with a packaging material dispenser;
• providing relative rotation between the packaging material dispenser and the load with a relative rotation drive mechanism;
• limiting one of a relative rotational speed and a packaging material dispensing speed, based on the other of the relative rotational speed and the packaging material dispensing speed, with a variable mechanical connection operatively coupling the packaging material dispenser to the relative rotation drive mechanism;
• and
• setting the limit based on a characteristic of the dispensed packaging material sensed by a sensing element operatively coupled to the variable mechanical connection.