TECHNICAL FIELD

The present invention relates generally to packaging systems, and, in particular, to a new and improved packaging machine.

BACKGROUND ART

Wrapping machines of the type that are used to hand-wrap packages with a thin, often clear, film are often used in supermarkets to wrap meat, cheese, etc. In a typical machine, a foam tray on which the meat or cheese is placed is hand-wrapped with a length of stretchable film that is dispensed from a roll on the wrapping machine. Once wrapped, the film is severed and the edges of the sheet are folded and tucked on the underside of the package. Heat is then used to fuse the film, thus sealing the package. A hot plate surface is heated to a predetermined temperature that is related to the temperature needed to cause melting or fusion of the film used to wrap the package.

DISCLOSURE OF THE INVENTION

The present invention provides a new and improved packaging machine of the type that is used to hand-wrap a package with a stretchable film. The present invention provides a supply of film for wrapping a package, a means for severing a length of the film and a hot plate surface for effecting fusion and sealing of the film that is wrapped around the package.

According to one aspect of the invention, a packaging machine for wrapping a package with heat-sensitive film is disclosed. The packaging machine includes a frame defining a wrapping surface. A film supply receptacle is adapted to receive a supply of heat-sensitive film. A cutting element is adapted to sever a length of heat-sensitive film from the supply used to wrap the package. A hot plate assembly is adapted to fuse the length of the heat-sensitive film wrapped around the package. The hot plate assembly includes a heating element. A controller is adapted to calculate a time period the heating element is energized to fuse the length of heat-sensitive film wrapped around the package based on an initial temperature of the heating element.

According to this aspect, the initial temperature of the heating element may be detected by a thermal feedback device. The thermal feedback device may be a thermistor. One of a thermal fuse and a ground-fault current interrupter may be adapted to interrupt energization of the heating element if a temperature of the heating element exceeds a temperature design value. The heating element may be a mica heater having a heating ramp rate of approximately 100° F. per second. A light emitting diode may be adapted to display at least two different colors to indicate at least two different operating statuses of the packaging machine.

According to another aspect of the invention, a packaging machine for wrapping a package with heat-sensitive film is disclosed. The packaging machine includes a frame defining a wrapping surface. A film supply receptacle is adapted to receive a supply of heat-sensitive film. A cutting element is adapted to sever a length of heat-sensitive film from the supply used to wrap the package. A hot plate assembly is adapted to fuse the length of heat-sensitive film wrapped around the package, the hot plate assembly including a heating element. A hot plate status indicator is adapted to indicate at least two different statuses of operation of the packaging machine.

According to this aspect, the hot plate status indicator may be a light emitting diode that displays a first color to indicate that the packaging machine is operating in a first status and a second color to indicate that the packaging machine is operating in a second status. A controller may be adapted to calculate a time period the heating element is energized to fuse the length of heat-sensitive film wrapped around the package based on an initial temperature of the heating element.

According to another aspect of the invention a method of operating a packaging machine to fuse heat-sensitive film a package is disclosed. The method includes detecting the presence of a package on a hot plate assembly of the packaging machine. A temperature of a heating element is measured. A time the heating element is energized is calculated based on the measured temperature of the heating element. The heating element is energized for the time calculated in response to the detection of the presence of the package on the hot plate assembly.

According to this aspect, the method may include the step of interrupting the step of energizing if the temperature of the heating element exceeds a temperature design value.

According to another aspect of the invention, a packaging machine for wrapping a package with heat-sensitive film is disclosed. The packaging machine includes a frame defining a wrapping surface. A film supply receptacle is adapted to receive a supply of heat-sensitive film. A heated rod is adapted to sever a length of heat-sensitive film from the supply used to wrap the package. A hot plate assembly is adapted to fuse the length of heat-sensitive film wrapped around the package. The hot plate assembly includes a mica heater heating element having a heating ramp rate of approximately 100° F. per second. The packaging machine further includes a package sensor. The heating element is energized in response to the package sensor detecting the package on the hot plate assembly. A controller is adapted to calculate a time period the heating element is energized to fuse the length of heat-sensitive film wrapped around the package based on an initial temperature of the heating element. A thermistor is adapted to sense the initial temperature of the heating element. A ground-fault current interrupter is adapted to interrupt energization of the heating element if a temperature of the heating element exceeds a temperature design value. A light emitting diode is adapted to display at least two different colors to indicate at least two different operating statuses of the packaging machine.

Additional features of the invention will become apparent and a fuller understanding obtained by reading the following detailed description made in conjunction with the accompanying drawings.

