초록 ▼

A package sensing system provides length, width and height signals to a film control system which selects the width and length of stretch film to be used by a film wrapping machine to wrap the sensed package. Package width is sensed by spring biased swing arms which active electrical switches upon d

A package sensing system provides length, width and height signals to a film control system which selects the width and length of stretch film to be used by a film wrapping machine to wrap the sensed package. Package width is sensed by spring biased swing arms which active electrical switches upon deflection by an entering package. A wide package is indicated if both swing arms are deflected. The length and height of a package are sensed by a generally vertical downwardly extending lever arm which is pivotally mounted above the package entryway into the machine. A first electrical switch coupled to the lever arm generates a length signal upon initial contact by an entering package and a second electrical switch coupled to the lever arm generates a height signal depending upon the ultimate deflection of the lever arm by the package. Two film widths are provided with the narrower of the two being selected for packages which activate neither the width sensing system or the height sensing system and the wider of the two films being selected upon activation of either of those sensing systems. The length of the film drawn is determined by the length of a measured package with that length being incrementally increased if a high package is sensed.

대표청구항 ▼

In a film wrapping machine including at least a wide roll and a narrow roll of continuous stretchable film, gripper means for drawing a section of one of said rolls of film into said machine, means for selectively presenting any one of said rolls of film to said gripper means, and means for controll

In a film wrapping machine including at least a wide roll and a narrow roll of continuous stretchable film, gripper means for drawing a section of one of said rolls of film into said machine, means for selectively presenting any one of said rolls of film to said gripper means, and means for controlling the stroke of said gripper means to determine the length of said section of film drawn into said machine, an improved package sensing and film control system comprising: lateral sensing means for generating a wide package signal and a narrow package signal representative of the width of a package entering said machine; longitudinal sensing means for generating signals representative of the length of a package entering said machine; vertical sensing means for generating a low package signal and a high package signal representative of the height of a package entering said machine; and control means responsive to said length signals, said width signals and said height signals for controlling said presenting means and said gripper controlling means to select both the width and length of the section of stretchable film drawn into said machine said control means interpreting said length signals as being one of a plurality of package lengths and responding to said package size signals to present the narrow film roll to said gripper means unless a wide package signal or a high package signal is received, in which case the wide film roll is presented and for controlling said gripper controlling means to draw the length of film indicated by said length sensing means with the next longer film length being drawn if a high package signal is received unless the maximum or minimum film length was initially indicated.