Article packaging machine and method of preventing the formation of defective packages

A method of controlling the operation of a packaging machine to prevent the formation of an empty package, the packaging machine having a supply of articles to be packaged, an endless infeed conveyor extending along at least a portion of a path of travel extending through the packaging machine, the infeed conveyor having a series of spaced article receiving flights defined along its length for being supplied with the articles to be packaged and being driven at a predetermined linear rate of speed in the direction of the path of travel by a first drive, a supply of packaging film, a packaging film forming shoe positioned along the path of travel downstream of the infeed conveyor for forming the film as a tube about the articles, and a pair of opposed and counter-rotating cutting heads positioned along the path of travel downstream of the film forming shoe, the packaging film being driven toward the film forming shoe by a second drive, and the cutting heads being driven by a third drive, said method comprising the steps of:

• a) determining an initial rotational position of the first drive, the second drive, and the third drive, respectively;
• b) establishing a base rotational position relationship of the second drive and the third drive with respect to one another;
• c) calculating a first position control trajectory profile;
• and
• d) establishing a first rotational position relationship of the second and third drives, respectively, with respect to the rotational position of the first drive.

A method of controlling the operation of a packaging machine, the packaging machine having a supply of articles to be packaged, an endless infeed conveyor extending along at least a portion of a path of travel extending through the packaging machine, the infeed conveyor having a series of spaced article receiving flights defined along its length for being supplied with the articles to be, a supply of packaging film, a packaging film forming shoe positioned along the path of travel downstream of the infeed conveyor for forming the film as a tube about the articles, and a pair of opposed and counter-rotating cutting heads positioned along the path of travel downstream of the film forming shoe, said method comprising the steps of:

• a) moving the articles to be packaged along the path of travel within the article receiving flights of the infeed conveyor packaged in the direction of the path of travel with a first drive;
• b) moving the packaging film in the direction of the path of travel toward the film forming shoe with a second drive;
• c) rotating the cutting heads of the cutting head assembly in the direction of the path of travel with a third drive;
• d) mapping a first rotational position relationship of the second drive and the third drive with respect to the first drive;
• d) detecting, with an article detector positioned upstream of the film forming shoe, whether an article is present within a first flight of the infeed conveyor as the flight moves along the path of travel;
• and
• e) in response to detecting the absence of an article within said first flight, retarding the rotational position of the second drive and of the third drive, respectively, with respect to the rotational position of the first drive while maintaining a fixed rotational position relationship between the second drive and the third drive.

A method of controlling the operation of a packaging machine to prevent the cutting of an article being packaged by the machine, the packaging machine having a supply of articles to be packaged, an endless infeed conveyor extending along and moving in the direction of a path of travel through the packaging machine, the infeed conveyor having a series of spaced article receiving flights defined along its length for being supplied with the articles to be packaged, a supply of packaging film, a packaging film forming shoe positioned along the path of travel downstream of the infeed conveyor for forming the packaging film as a tube about the spaced articles, a fin seal assembly positioned along the path of travel downstream of the film forming shoe for forming a fin seal in the tube of packaging film, and a cutting head assembly having a pair of counter-rotating sealing and cutting heads positioned along the path of travel downstream of the fin seal assembly, said method comprising the steps of:

• a) moving the articles to be packaged along the path of travel within the article receiving flights of the infeed conveyor with a first drive;
• b) moving the packaging film in the direction of the path of travel toward the film forming shoe with a second drive;
• c) rotating the cutting heads of the cutting head assembly in the direction of the path of travel with a third drive;
• d) establishing a base rotational position relationship of the first drive and the second drive with respect to one another, and calculating a first rotational position relationship between the rotational positions of the first and the second drives, respectively, in said base relationship with respect to the rotational position of the third drive;
• e) detecting, with an article detector positioned with respect to the fin seal assembly, whether a first article is present within the tube of packaging film moving toward the cutting head assembly;
• and
• f) in response to detecting the presence of the first article within the tube of packaging film, calculating a second rotational position relationship between the rotational position of the third drive with respect to the rotational positions of the first and second drives, respectively, while maintaining said base relationship between the first drive and the second drive with respect to one another.

A packaging machine for packaging articles, the packaging machine having a path of travel extending through the packaging machine, a supply of articles to be packaged, and a supply of packaging film, said packaging machine comprising:

• an endless infeed conveyor extending along at least a portion of a path of travel, said infeed conveyor having a series of spaced article receiving flights defined along its length for being supplied with the articles to be packaged and being driven in the direction of the path of travel by a first drive;
• a packaging film forming shoe positioned along the path of travel downstream of the infeed conveyor for forming the film as a tube about the articles, the packaging film being driven toward the film forming shoe by a second drive;
• a pair of opposed and counter-rotating cutting heads positioned along the path of travel downstream of the film forming shoe, the cutting heads being driven by a third drive;
• and
• a machine controller in operative communication with said first, said second, and said third drives, said controller being constructed and arranged to:
• a) determine an initial rotational position of the first drive, the second drive, and the third drive, respectively;
• b) establish a base rotational position relationship of the second drive and the third drive with respect to one another;
• c) calculate at least a first position control trajectory profile for controlling the rotational position of said second and third drives in said base rotational position with respect to the rotational position of said first drive;
• and
• d) establish at least a first rotational position relationship of the second and third drives, respectively, with respect to the rotational position of the first drive.

In a packaging machine for packaging articles, the packaging machine having a path of travel extending through the packaging machine, a supply of articles to be packaged, a supply of packaging film, an endless infeed conveyor extending along at least a portion of a path of travel and having a series of spaced article receiving flights defined along its length for being supplied with the articles to be packaged and being driven in the direction of the path of travel by a first drive, a packaging film forming shoe positioned along the path of travel downstream of the infeed conveyor for forming the film as a tube about the articles, the packaging film being driven toward the film forming shoe by a second drive, and a pair of opposed and counter-rotating cutting heads positioned along the path of travel downstream of the film forming shoe, the cutting heads being driven in the direction of the path of travel by a third drive, the improvement comprising:

• a machine controller in operative communication with the first, the second, and the third drives, respectively, said controller being constructed and arranged to:
• a) determine an initial rotational position of the first drive, the second drive, and the third drive, respectively;
• b) establish a base rotational position relationship of the second drive and the third drive with respect to one another;
• c) calculate a first active position control trajectory profile for controlling the rotational position of the second drive and the third with respect to the rotational position of the first drive;
• d) continuously calculate an inactive position control trajectory profile as said active profile operates the packaging machine;
• and
• e) to selectively replace the active profile with the inactive profile during packaging machine operation.

A method of controlling the operation of an article packaging machine to prevent the formation of empty packages, the packaging machine having a supply of articles to be packaged, an endless infeed conveyor extending along at least a portion of a path of travel extending through the packaging machine, the infeed conveyor having a series of spaced article receiving flights defined along its length for being supplied with the articles to be packaged and being driven in the direction of the path of travel by an infeed conveyor drive axis, a supply of packaging film, a packaging film forming shoe positioned along the path of travel downstream of the infeed conveyor for forming the film as a tube about the articles, and a pair of opposed and counter-rotating cutting heads positioned along the path of travel downstream of the film forming shoe, the packaging film being driven toward the film forming shoe by a film feed drive axis, and the cutting heads being driven by a cutting head drive axis, said method comprising the steps of:

• a) determining an initial rotational position of the infeed conveyor drive axis, the film feed drive axis, and the cutting head drive axis, respectively;
• b) establishing a base rotational position relationship between the rotational position of the film feed drive axis with respect to the rotational position of the cutting head drive axis during the sealing and cutting of the tube of packaging film formed about the articles being packaged, and mapping said base relationship to the rotational position of the infeed conveyor drive axis;
• c) examining the flights of the infeed conveyor with a detection means positioned upstream of the film forming shoe and along the infeed conveyor for signaling whether the respective article receiving flights of the infeed conveyor contain an article to be packaged therein;
• d) calculating a first position control trajectory profile for controlling the rotational position of the film feed drive axis and the cutting head drive axis with respect to the rotational position of the infeed conveyor drive axis;
• e) transferring the articles from the flights of the infeed conveyor into the tube of packaging film as it is being formed about the articles at the film forming shoe;
• f) calculating a second position control trajectory profile in response to the detection of an empty article receiving flight, and in response thereto rotating the film feed drive axis and cutting head drive axis at a speed greater than zero and through a distance equal to a single packaging cycle, and simultaneously rotating the infeed drive axis through a distance equal to two of said cycles;
• g) replacing the first position control trajectory profile with the second position control trajectory profile;
• and
• h) replacing the second position control trajectory profile with the first position control trajectory profile upon completion of the second position control trajectory profile.

A method of controlling the operation of an article packaging machine to prevent the formation of multiple consecutive empty packages, the packaging machine having a supply of articles to be packaged, an endless infeed conveyor extending along at least a portion of a path of travel extending through the packaging machine, the infeed conveyor having a series of spaced article receiving flights defined along its length for being supplied with the articles to be packaged and being driven in the direction of the path of travel by an infeed conveyor drive axis, a supply of packaging film, a packaging film forming shoe positioned along the path of travel downstream of the infeed conveyor for forming the film as a tube about the articles, and a pair of opposed and counter-rotating cutting heads positioned along the path of travel downstream of the film forming shoe, the packaging film being driven toward the film forming shoe by a film feed drive axis, and the cutting heads being driven by a cutting head drive axis, said method comprising the steps of:

• a) determining an initial rotational position of the infeed conveyor drive axis, the film feed drive axis, and the cutting head drive axis, respectively;
• b) establishing a base rotational position relationship between the rotational position of the film feed drive axis with respect to the rotational position of the cutting head drive axis during the sealing and cutting of the tube of packaging film formed about the articles being packaged, and mapping said base relationship to the rotational position of the infeed conveyor drive axis;
• c) examining the flights of the infeed conveyor with a detection means positioned upstream of the film forming shoe and along the infeed conveyor, said detection means signaling whether the respective article receiving flights of the infeed conveyor contain an article to be packaged therein;
• d) calculating a first position control trajectory profile for controlling the rotational position of the film feed drive axis and the cutting head drive axis with respect to the rotational position of the infeed conveyor drive axis;
• e) transferring the articles from the flights of the infeed conveyor into the tube of packaging film as it is being formed about the articles at the film forming shoe;
• f) calculating a second position control trajectory profile in response to the detection of at least two consecutive empty article receiving flights, and in response thereto continuing to rotate the infeed conveyor drive axis while dwelling the rotation of the film feed drive and cutting head drive axes, respectively, in a fixed position with respect to the rotational position of the infeed conveyor drive axis;
• g) replacing the first position control trajectory profile with the second position control trajectory profile;
• and
• h) replacing the second position control trajectory profile with the first position control trajectory in response to detecting an article within an upstream article receiving flight.

A method of controlling the operation of an article packaging machine, the packaging machine having a supply of articles to be packaged, an endless infeed conveyor extending along at least a portion of a path of travel extending through the packaging machine, the infeed conveyor having a series of spaced article receiving flights defined along its length for being supplied with the articles to be packaged and being driven in the direction of the path of travel by an infeed conveyor drive axis, a supply of packaging film, a packaging film forming shoe positioned along the path of travel downstream of the infeed conveyor for forming the film as a tube about the articles, and a pair of opposed and counter-rotating cutting heads positioned along the path of travel downstream of the film forming shoe, the packaging film being driven toward the film forming shoe by a film feed drive axis, and the cutting heads being driven by a cutting head drive axis, to prevent the collision of the cutting heads with an article out of a predetermined packaging position within the tube of packaging film, said method comprising the steps of:

• a) determining an initial rotational position of the infeed conveyor drive axis, the film feed drive axis, and the cutting head drive axis, respectively;
• b) establishing a base rotational position relationship between the rotational position of the infeed conveyor drive axis and the film feed drive axis, and mapping the rotational position of the cutting head drive axis to said base relationship;
• c) transferring the articles present within the flights of the infeed conveyor into the tube of packaging film as it is being formed about the articles at the film forming shoe;
• d) examining the tube of packaging filmed and the articles entrained therein with a detection means, positioned intermediate the film forming shoe and the cutting heads, for signaling whether an article is out of a predetermined position within the tube of packaging film;
• e) calculating a first position control trajectory profile for controlling the rotational position of the cutting head drive axis with respect to the rotational position of the infeed conveyor drive axis and the film feed drive axis;
• f) calculating a second position control trajectory profile in response to the detection of an out of position article, and in response thereto rotating the cutting head drive axis at a speed greater than zero and a through a distance equal to a single packaging cycle and simultaneously rotating the infeed conveyor drive axis and the film feed drive axis through a distance equal to two of said cycles;
• g) replacing the first position control trajectory profile with the second position control trajectory profile;
• and
• h) replacing the second position control trajectory profile with the first position control trajectory profile upon completion of the second position control trajectory profile.