Packaging machine with device for monitoring remaining amount of web in a roll

A warning device in combination with a web roll having a web wound around a core shaft and rotating to thereby cause said web to unwind therefrom, said warning device comprising:

• rotation detecting means for detecting speed of rotation .omega. of said web roll;
• calculating means for using said speed of rotation .omega. detected by said rotation detecting means, a unit length L of said web required for a product and a number N of times said unit length L of said web is pulled out of said web roll per unit time, thereby calculating an outer radius value R indicative of the current outer radius of said web roll;
• and
• comparing means for determining a comparison value based on a core shaft radius value r indicative of the outer radius of said core shaft, making a comparison between said comparison value and said outer radius value R, and causing an alarm signal to be outputted based on the result of said comparison.

A packaging machine comprising:

• a web supporting means supporting a web roll having a web of a bag-making material wound around a core shaft;
• a former for forming said web into a tubular shape;
• web guiding means for guiding said web from said web roll to said former and said tubularly formed web in a longitudinal direction;
• a longitudinal sealer for sealing side edges of said tubularly formed web together in said longitudinal direction;
• a transverse sealer having a pair of sealing means for compressing and sealing sheets of said tubularly formed web together therebetween transversely to said longitudinal direction and thereby forming a bag;
• rotation detecting means for detecting speed of rotation .omega. of said web roll;
• display means for displaying information thereon;
• and
• calculating means for using said speed of rotation .omega. detected by said rotation detecting means, a unit length L of said web required for a product and a number N of times said unit length L of said web is pulled out of said web roll per unit time, thereby calculating an outer radius value R indicative of the current outer radius of said web roll, and causing numbers calculated by said calculating means to be displayed on said display means.

A packaging machine comprising:

• a web supporting means supporting a web roll having a web of a bag-making material wound around a core shaft;
• a former for forming said web into a tubular shape;
• web guiding means for guiding said web from said web roll to said former and said tubularly formed web in a longitudinal direction;
• a longitudinal sealer for sealing side edges of said tubularly formed web together in said longitudinal direction;
• a transverse sealer having a pair of sealing means for compressing and sealing sheets of said tubularly formed web together therebetween transversely to said longitudinal direction and thereby forming a bag;
• rotation detecting means for detecting speed of rotation .omega. of said web roll;
• calculating means for using said speed of rotation .omega. detected by said rotation detecting means, a unit length L of said web required for a product and a number N of times said unit length L of said web is pulled out of said web roll per unit time, thereby calculating an outer radius value R indicative of the current outer radius of said web roll;
• and
• comparing means for determining a comparison value based on a core shaft radius value r indicative of the outer radius of said core shaft, making a comparison between said comparison value and said outer radius value R, and causing an alarm signal to be outputted based on the result of said comparison.