An exemplary air cushion inflation machine includes: a first terminal connected to a direct current input; a second terminal; a reference resistor powered by the direct current input; an op-amp; and a transistor. The first terminal of the op-amp is connected to a variable voltage source and the second terminal of the op-amp is connected to the reference resistor. The transistor has a base connected to an output of the op-amp, an emitter connected to the reference resistor, and a collector connected to a first terminal of a sealing band apparatus having first and second terminals. A meltable material placed between the first and second terminals is melted by resistance of current flowing between the first and second terminals. The variable voltage source changes voltage based on a voltage drop measured across the first and second terminals by a voltage measurement device and the constant current.

A power convertor configured to output power to an electrofusion welding coupler for performing electrofusion welding. The power convertor comprises an array of connected DC to DC power convertor circuits. In use, the array of connected DC to DC power convertor circuits is configured to receive, at a first interface, power at a first voltage level from a battery and output power, at a second interface, at a second voltage level to provide power to electrofusion welding cable means. The DC to DC power convertors are arranged in a buck-boost configuration which can operate in a boost mode in which the first voltage level is less than the second voltage level and in a buck mode in which the first voltage level is greater than the second voltage level.

A process is provided for heat sealing substrate layers. The process comprising: conveying an upper die having a heating conductor and a lower die having a heating conductor to a sealing region, where a substrate is applied to one or more items; activating a power supply system; monitoring, via the power supply system, a temperature of the heating conductor of the upper die when in the sealing region; monitoring, via the power supply system, a temperature of the heating conductor of the lower die when in the sealing region, wherein the monitoring of the temperature of the heating conductor of the upper die is performed independently of the monitoring of the temperature of the heating conductor of the lower die; supplying power to the upper die based on the temperature of the heating conductor of the upper die; supplying power to the lower die based on the temperature of the heating conductor of the lower die, wherein the power is supplied to the lower die independently of the power being supplied to the upper die.

An apparatus is configured to make containers from sheet material. The apparatus includes a supply station for supplying a film having at least one folded portion having three or more film flaps folded and superimposed with respect to each other; a welding station configured to receive the film. The welding station comprises a welding head configured for welding the folded portion of the film and forming a container defining a housing compartment; the welding head comprises a heater made of electrically conductive material whose electrical resistivity, at least in a predetermined temperature range, decreases upon the increase of the temperature of the same electrically conductive material.

A process is provided for heat sealing substrate layers. The process comprising: conveying an upper die having a heating conductor and a lower die having a heating conductor to a sealing region, where a substrate is applied to one or more items; activating a power supply system; monitoring, via the power supply system, a temperature of the heating conductor of the upper die when in the sealing region; monitoring, via the power supply system, a temperature of the heating conductor of the lower die when in the sealing region, wherein the monitoring of the temperature of the heating conductor of the upper die is performed independently of the monitoring of the temperature of the heating conductor of the lower die; supplying power to the upper die based on the temperature of the heating conductor of the upper die; supplying power to the lower die based on the temperature of the heating conductor of the lower die, wherein the power is supplied to the lower die independently of the power being supplied to the upper die.

A resistance welding apparatus can employ a modular power supply system with multiple power supply modules and leads for electrically connecting the modular power supply system to a welding resistor. The resistance welding apparatus is selectively configurable in at least three of (i) a first configuration in which the leads connect the first power supply module to the resistor and the second power supply module is disconnected from the resistor; (ii) a second configuration in which the leads connect the second power supply module to the resistor and the first power supply module is disconnected from the resistor; (iii) a third configuration in which the leads connect the first and second power supply modules to the resistor in series; and (iv) a fourth configuration in which the leads connect the first and second power supply modules to the resistor in parallel.

A machine converts a web of preformed pouches, which are defined by transverse seals extending from a remote edge, into inflated dunnage units. A sealing arrangement is positioned to provide a longitudinal seal intersecting the transverse seals to close the preformed pouches and form a dunnage unit. The sealing arrangement has at least two sealing belts. Each belt is positioned so that respective first sides engage a surface of the web and pull the web through sealing elements positioned on either side of the web. A heating element is on a second side of the first belt not engaging the web. A compliant material is on a second side of the second belt not engaging the web. As the web passes between the heating element and compliant material, imperfections in the web are smoothed by the compliant material and the layers of the web are sealed by the heating element.

A process for packaging a product arranged on a support comprising unrolling a film, moving the film to a packaging assembly defining at its inside a packaging chamber, progressively moving a number of supports inside the packaging chamber of the packaging assembly, closing the packaging chamber with the film sheets held above the respective support, optionally causing one or both of: a gas withdrawal from the hermetically closed packaging chamber and gas injection of a gas mixture of controlled composition, heat sealing the film to said support, wherein the heat sealing uses one or more heaters having heating surfaces which are heated for discrete and short time periods only. An apparatus for performing the above process is also disclosed.

A process for packaging a product arranged on a support comprising unrolling a film, moving the film to a packaging assembly defining at its inside a packaging chamber, progressively moving a number of supports inside the packaging chamber of the packaging assembly, closing the packaging chamber with the film sheets held above the respective support, optionally causing one or both of: a gas withdrawal from the hermetically closed packaging chamber and gas injection of a gas mixture of controlled composition, heat sealing the film to said support, wherein the heat sealing uses one or more heaters having heating surfaces which are heated for discrete and short time periods only. An apparatus for performing the above process is also disclosed.

The present invention discloses a heat radiator, especially an infrared radiator, having at least one radiation source by means of which supplied electrical energy is convertible into heat radiation, as well as a control. This control comprises at least one frequency converter having a first, a second and a third output so that between the first and the third output a first alternating current is providable and between the second and the third output a second alternating current is providable by means of which the at least one radiation source is operable.