A welding apparatus (1) for radio-frequency, RF, welding, comprises: a clamp (10) having two electrodes (100, 101; 100′, 101′) being movable with respect to one another for clamping one or more items (2; 2′) therebetween for a welding process; and an RF power supply (11) for providing an RF welding current to the electrodes (100, 101; 100′, 101′) of the clamp (10), the RF power supply being adapted to change the frequency of the RF welding current during the welding process.

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 method of dissipating heat from a surface of a first thermoplastic composite (TPC) being inductively welded with a second thermoplastic composite (TPC) includes flexing a heat sink during placement to conform to the surface of the first TPC, cooling the heat sink, applying inductive heat to a weld interface area between the first TPC and the second TPC, and drawing off heat via the heat sink from the surface of the first TPC.

A heat seal between a plastic bag and a plastic sheet is used to provide a more secure and reliable seal to define a modified atmosphere for a pallet of perishables. The heat seal reduces atmosphere failures and aids in providing a more consistent atmosphere in the pallet bag system thus reducing the number of pallets that have an out of specification atmosphere. The heat seal may be created with a heating sealing apparatuses that is part of a system used to load and seal a load of containers of perishables onto a pallet. The heat sealing apparatus uses two heated rollers coupled to a rotating arm to contact and heat seal a plastic bag to a plastic seal that enclose a palletized load of perishables that are rotated on a turntable.

A system includes a dip tube, a feed line, and a check valve. The dip tube is inserted through an opening in a source of chemical precursor and into the chemical precursor in the source. A portion of the feed line is located in the dip tube. The feed line passes out of the dip tube. The chemical precursor is capable of flowing out of the source through the feed line in a downstream direction. The check valve is located in the portion of the feed line in the dip tube. The check valve permits the chemical precursor to pass substantially only in the downstream direction. The feed line is coupled to a transfer pump that draws the chemical precursor out of the source through the portion of the feed line in the dip tube.

A method of welding/joining corrugated pipe segments, an apparatus configured to weld/join corrugated pipe segments, and a method of circulating water are disclosed. The method of welding/joining corrugated pipe segments includes holding or securing an end of each of the corrugated pipe segments with a jig, and welding the ends of the corrugated pipe segments together. The jig includes at least two rings, each configured to receive one of the ends of the corrugated pipe segments, and a brace or connector connected to each of the two rings. The apparatus includes the jig, a welding ring configured to receive the ends of the corrugated pipe segments, a resistive heating coil for heating the welding ring, and a control circuit configured to control a temperature of the resistive heating coil and maintain the temperature of the resistive heating coil once a target temperature is reached.

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 sensorless temperature sensing and control system and method uses electrical voltage and current feedback signals to monitor and control the temperature of heating elements used in a heat sealing process wherein sensors are not physically connected to a heat seal bar during the heat sealing process. After calibration of a heat seal bar using a sensor, voltage and current feedback signals are processed by a programmable logic controller (PLC) to calculate the real-time electrical resistance of each heating element. Data and electrical resistance is used to calculate real-time temperature of the heat seal bar during heating.

An apparatus for thermally joining thermoplastic fiber composite components includes a pressurization arrangement for jointly covering, at least in a region of a joining zone, thermoplastic fiber composite components to be joined and applying pressure to the thermoplastic fiber composite components to press the thermoplastic fiber composite components against one another, at least in the joining zone, the pressurization arrangement being flexible, at least in some section or sections. A welding device is configured for welding the fiber composite components in the joining zone during pressurization. The pressurization arrangement and welding device are configured to weld the thermoplastic fiber composite components in a pressurized state in the joining zone. The pressurization arrangement is configured to maintain pressurization independently of the welding device until the joining zone solidifies. A cover is also disclosed for a pressurization device for thermally joining thermoplastic fiber composite components.