Method of monitoring transverse sealing in a packaging unit for continuously forming sealed packages containing pourable food products

A packaging unit comprising a sealing device for sealing a tube made of packaging material having an electrically conducting layer, a heat-seal layer, and a layer of fibrous material, and filled with a pourable food product;

• said sealing device comprising:
• at least one pair of jaws where a first jaw carries an inductor;
• means for mutually compressing said jaws, a sealing current source connected to said inductor and generating a sealing current;
• and measuring means for measuring electric output quantities relative to said electric current;
• wherein measuring means measures quantities correlating with power absorbed by said packaging material during sealing;
• and
• means for calculating a difference in a distance between the jaws in said pair before sealing and after sealing.

A method of monitoring transverse sealing on a packaging unit comprising a sealing current source and at least one pair of jaws;

• at least a first of the jaws in said pair carrying an inductor;
• the method comprising the steps of:
• compressing a tube of packaging material, the packaging material having at least one electrically conducting layer, a heat-seal layer, and a layer of fibrous material which is filled with a pourable food product;
• supplying said inductor, during the compressing step, with an electric current to generate a sealing current in said electrically conducting layer;
• measuring electric output quantities relative to said electric current, wherein the operation of measuring electric output quantities correlates with the power absorbed by said packaging material during the operation of supplying a sealing current;
• calculating both a load impedance recognized by said source and an energy of the current generated by said source;
• and
• acquiring a difference in the distance between the jaws in said pair before and after sealing.

A method of monitoring transverse sealing on a packaging unit comprising a sealing current source and at least one pair of jaws;

• at least a first of the jaws in said pair carrying an inductor;
• the method comprising the steps of:
• compressing a tube of packaging material, the packaging material having at least one electrically conducting layer, a heat-seal layer, and a layer of fibrous material which is filled with a pourable food product;
• supplying said inductor, during the compressing step, with an electric current to generate a sealing current in said electrically conducting layer;
• measuring electric output quantities relative to said electric current, where the operation of measuring electric output quantities correlates with the power absorbed by said packaging material during the operation of supplying a sealing current;
• monitoring both parameters relative to power supplied by said inductor to said packaging material and parameters relative to a temperature of said layer of electrically conducting material;
• monitoring a temperature of the pourable food product fed into said tube;
• determining characteristics of said packaging material;
• and
• monitoring a difference in the distance between the jaws in said pair before and after sealing.

A method of monitoring transverse sealing on a packaging unit comprising a sealing current source and at least one pair of jaws;

• at least a first of the jaws in said pair carrying an inductor;
• the method comprising the steps of:
• compressing a tube of packaging material, the packaging material having at least one electrically conducting layer, a heat-seal layer, and a layer of fibrous material which is filled with a pourable food product;
• supplying said inductor, during the compressing step, with an electric current to generate a sealing current in said electrically conducting layer;
• measuring electric output quantities relative to said electric current, where the operation of measuring electric output quantities correlates with the power absorbed by said packaging material during the operation of supplying a sealing current;
• monitoring both parameters relative to power supplied by said inductor to said packaging material and parameters relative to a temperature of said layer of electrically conducting material;
• monitoring a temperature of the pourable food product fed into said tube;
• determining characteristics of said packaging material;
• monitoring a difference in the distance between the jaws in said pair before and after sealing;
• a temperature of a cooling fluid of said inductor;
• measuring said thickness directly;
• acquiring a load impedance value of said source;
• and
• acquiring a phase angle value of said electric output quantities.

A method of monitoring transverse sealing on a packaging unit comprising a sealing current source and at least one pair of jaws;

• at least a first of the jaws in said pair carrying an inductor;
• the method comprising the steps of:
• compressing a tube of packaging material, the packaging material having at least one electrically conducting layer, a heat-seal layer, and a layer of fibrous material which is filled with a pourable food product;
• supplying said inductor, during the compressing step, with an electric current to generate a sealing current in said electrically conducting layer;
• measuring electric output quantities relative to said electric current, wherein the operation of measuring electric output quantities correlates with the power absorbed by said packaging material during the operation of supplying a sealing current;
• and
• acquiring a difference in the distance between the jaws in said pair before and after sealing.

A method of monitoring transverse sealing on a packaging unit comprising a sealing current source and at least one pair of jaws;

• at least a first of the jaws in said pair carrying an inductor;
• the method comprising the steps of:
• compressing a tube of packaging material, the packaging material having at least one electrically conducting layer, a heat-seal layer, and a layer of fibrous material which is filled with a pourable food product;
• supplying said inductor, during the compressing step, with an electric current to generate a sealing current in said electrically conducting layer;
• measuring electric output quantities relative to said electric current, wherein the operation of measuring electric output quantities correlates with the power absorbed by said packaging material during the operation of supplying a sealing current, the operation of measuring electric output quantities which correlates with the power absorbed further comprising monitoring both parameters relative to power supplied by said inductor to said packaging material and parameters relative to a temperature of said layer of electrically conducting material, where said step of monitoring parameters relative to a temperature of the electrically conducting layer further comprises determining characteristics of said packaging material;
• and
• the step of determining characteristics of said packaging material further comprising monitoring a difference in the distance between the jaws in said pair before and after sealing.

A method of monitoring transverse sealing on a packaging unit comprising a sealing current source and at least one pair of jaws;

• at least a first of the jaws in said pair carrying an inductor;
• the method comprising the steps of:
• compressing a tube of packaging material, the packaging material having at least one electrically conducting layer, a heat-seal layer, and a layer of fibrous material which is filled with a pourable food product;
• supplying said inductor, during the compressing step, with an electric current to generate a sealing current in said electrically conducting layer;
• measuring electric output quantities relative to said electric current, where the operation of measuring electric output quantities correlates with the power absorbed by said packaging material during the operation of supplying a sealing current, the operation of measuring electric output quantities which correlate with the power absorbed further comprising monitoring both parameters relative to power supplied by said inductor to said packaging material and parameters relative to a temperature of said layer of electrically conducting material, where said step of monitoring parameters relative to a temperature of the electrically conducting layer further comprises monitoring a temperature of the pourable food product fed into said tube, said step of monitoring parameters relative to a temperature of the electrically conducting layer further comprises determining characteristics of said packaging material;
• and
• the step of determining characteristics of said packaging material further comprising
• monitoring a type of packaging material, wherein said step of monitoring a thickness of said electrically conducting layer further comprises measuring said thickness directly and acquiring a load impedance value of said source and a phase angle value of said electric output quantities;
• and
• a difference in the distance between the jaws in said pair before and after sealing.

A method of monitoring transverse sealing on a packaging unit comprising a sealing current source and at least one pair of jaws;

• at least a first of the jaws in said pair carrying an inductor;
• the method comprising the steps of:
• compressing a tube of packaging material comprising at least one electrically conducting layer, a heat-seal layer, and a layer of fibrous material, and which is filled with a pourable food product;
• supplying said inductor, during the compressing step, with an electric current to generate a sealing current in said electrically conducting layer;
• measuring electric output quantities relative to said electric current;
• and
• measuring quantities correlated with the power absorbed by said packaging material during said step of supplying a sealing current, wherein said step of measuring quantities comprises calculating a difference in the distance between the jaws in said pair before and after sealing.

A method of monitoring transverse sealing on a packaging unit comprising a sealing current source and at least one pair of jaws;

• at least a first of the jaws in said pair carrying an inductor;
• the method comprising the steps of:
• compressing a tube of packaging material, the packaging material having at least one electrically conducting layer, a heat-seal layer, and a layer of fibrous material which is filled with a pourable food product;
• supplying said inductor, during the compression operation, with an electric current to generate a sealing current in said electrically conducting layer;
• measuring electric output quantities relative to said electric current, wherein the operation of measuring electric output quantities correlates with power absorbed by said packaging material during the operation of supplying a sealing current, the operation of measuring electric output quantities including monitoring parameters relative to power supplied by the inductor to the packaging material and monitoring parameters relative to a temperature of the electrically conducting layer, the operation of monitoring parameters relative to a temperature of the electrically conducting layer including determining characteristics of the packaging material, wherein the operation of determining characteristics of the packaging material includes at least one of the following:
• monitoring a thickness of said electrically conducting layer;
• monitoring a thickness of said layer of fibrous material;
• monitoring a thickness of said heat-seal layer;
• monitoring local variations in the thickness of said heat-seal layer;
• monitoring a quality of said heat-seal layer;
• and
• monitoring a type of packaging material;
• calculating both a load impedance recognized by said source and an energy of the current generated by said source;
• and
• acquiring at least one of the following:
• a distance between the jaws in said pair;
• a difference in the distance between the jaws in said pair before and after sealing;
• a temperature of a cooling fluid of said inductor;
• a pressure exerted by said jaws;
• or
• a temperature of said pourable food product.