Abstract: A packaging machine of the type that is used to hand-wrap a package with a stretchable film that is heat-fused/sealed. The machine includes a supply of film for wrapping a package and a hot plate mechanism for heat fusing the film after the package is wrapped. The hot plate mechanism includes a fever arm that moves a sealing platform from a raised position to a lowered, heat sealing position when the package is placed on the platform. A control circuit energizes a heating element forming part of the sealing platform and causes it to reach a desired heating temperature in 2 to 4 seconds, whereby fusing of the sealing film is achieved. An interval timer is used to control a signaling device such as a light to Indicate the machine is in a heating cycle. A separate timer, in conjunction with a temperature sensing thermistor, controls a length of time the heating element is energized and terminates power to the heating element prior to the end of a sealing Interval if a predetermined temperature is exceeded.

Abstract: A packaging machine including a supply of film for wrapping a package and a hot plate for heat fusing the film of a wrapped package. Power to the heating element is only delivered to the element during a heating cycle, thus conserving electrical power. A photo eye senses the package and a control circuit energizes the heating element the element reaches a desired heating temperature in 2 to 4 seconds. The frame of the machine includes a lower base member to which an upper base plate, preferably formed from a continuous sheet, is rigidly attached. The upper plate includes a support surface for the hot plate, a vertical wall to which the photo eye is attached that is interconnected with the support surface by a curved transition surface. The upper base plate also includes a lateral, rearwardly extending plate portion which defines at least a portion of a hardware enclosure.

Abstract: A packaging machine of the type that is used to hand-wrap a package with a stretchable film that is heat-fused/sealed. The machine includes a supply of film for wrapping a package and a hot plate mechanism for heat fusing the film after the package is wrapped. The hot plate mechanism includes a fever arm that moves a sealing platform from a raised position to a lowered, heat sealing position when the package is placed on the platform. A control circuit energizes a heating element forming part of the sealing platform and causes it to reach a desired heating temperature in 2 to 4 seconds, whereby fusing of the sealing film is achieved. An interval timer is used to control a signaling device such as a light to Indicate the machine is in a heating cycle. A separate timer, in conjunction with a temperature sensing thermistor, controls a length of time the heating element is energized and terminates power to the heating element prior to the end of a sealing Interval if a predetermined temperature is exceeded.

Abstract: An operator selects an operating characteristic, such as a degree of extension or force of an extension member (66) of a thermal actuator (16), with an input circuit (10). The input control circuit generates a reference signal. A feedback circuit (18) monitors a characteristic of the thermal actuator such as a temperature of its internal polymer, extension of the extension member, force, or the like, and generates a corresponding feedback signal. An error circuit (12) compares the reference and feedback signals and generates an error signal in accordance therewith. A dither circuit (30) generates an oscillating dither signal that is superimposed on one of the control and feedback signals before comparison by the error circuit. A power conversion circuit (14) adjusts an amount of electrical power supplied to a heating element (54) of the thermal actuator in accordance with the error signal.