A roll bending machine includes a roller unit and a tension device. The roller unit rolls and bends a strip member at a rolling rate varying in a width-wise direction of the strip member. The tension device applies tension to the strip member after being rolled by the roller unit in a rolling direction of the strip member, thereby reducing compressive stress which usually result in formation of wrinkles on the strip member. This minimizes the probability of formation of wrinkles on the strip member.

A roll bending machine includes a roller unit and a tension device. The roller unit rolls and bends a strip member at a rolling rate varying in a width-wise direction of the strip member. The tension device applies tension to the strip member after being rolled by the roller unit in a rolling direction of the strip member, thereby reducing compressive stress which usually result in formation of wrinkles on the strip member. This minimizes the probability of formation of wrinkles on the strip member.

A flame port structure for burning a gas includes a first continuous spiral strip, a second continuous spiral strip and a first outflow passage. The first continuous spiral strip has a first side edge, a second side edge and a first plurality of annular segments, and the second continuous spiral strip has a third side edge, a fourth side edge and a second plurality of annular segments, wherein each of the first plurality of annular segments and each of the second plurality of annular segments respectively have two first longitudinal opposite surfaces and two second longitudinal opposite surfaces. The first outflow passage has a first defining wall formed on each of the first respective longitudinal surfaces from the first side edge to the second side edge. The first outflow passage is structured so that the gas produces a specific combustion.

A flame port structure for burning a gas includes a first continuous spiral strip, a second continuous spiral strip and a first outflow passage. The first continuous spiral strip has a first side edge, a second side edge and a first plurality of annular segments, and the second continuous spiral strip has a third side edge, a fourth side edge and a second plurality of annular segments, wherein each of the first plurality of annular segments and each of the second plurality of annular segments respectively have two first longitudinal opposite surfaces and two second longitudinal opposite surfaces. The first outflow passage has a first defining wall formed on each of the first respective longitudinal surfaces from the first side edge to the second side edge. The first outflow passage is structured so that the gas produces a specific combustion.

Methods for forming thin wall tubing into a tightly-coiled helical duct comprise selecting a thin wall tube with an outside tube diameter and a wall thickness that is less than 15% of the outside tube diameter; and bending the thin wall tube to form the tightly-coiled helical duct so that an outside duct diameter of the tightly-coiled helical duct is less than four times the outside tube diameter.

Methods for forming thin wall tubing into a tightly-coiled helical duct comprise selecting a thin wall tube with an outside tube diameter and a wall thickness that is less than 15% of the outside tube diameter; and bending the thin wall tube to form the tightly-coiled helical duct so that an outside duct diameter of the tightly-coiled helical duct is less than four times the outside tube diameter.

Tightly-coiled helical ducts for centrifugal air separators may be formed with the tools and methods disclosed herein. A helical coil toolset includes a helically grooved mandrel and an entry block. The helical groove of the mandrel has a small helix inside diameter relative to a width of the helical groove. The entry block has a guide channel to guide a tube to the helical groove and a mandrel channel to receive the mandrel. Methods include forming tubing into a tightly-coiled helical duct by filling a tube with fine particles, positioning the tube in the helical groove of a helically grooved mandrel, fixing the tube relative to the mandrel, assembling an entry block around the tube and around the mandrel, and bending the filled tube around the helically grooved mandrel into the tightly-coiled helical duct by rotating the mandrel relative to the entry block.

Tightly-coiled helical ducts for centrifugal air separators may be formed with the tools and methods disclosed herein. A helical coil toolset includes a helically grooved mandrel and an entry block. The helical groove of the mandrel has a small helix inside diameter relative to a width of the helical groove. The entry block has a guide channel to guide a tube to the helical groove and a mandrel channel to receive the mandrel. Methods include forming tubing into a tightly-coiled helical duct by filling a tube with fine particles, positioning the tube in the helical groove of a helically grooved mandrel, fixing the tube relative to the mandrel, assembling an entry block around the tube and around the mandrel, and bending the filled tube around the helically grooved mandrel into the tightly-coiled helical duct by rotating the mandrel relative to the entry block.

A control method for a winding wire manufacturing device that includes a base, a clamp, a bending top and a controller, includes a first process of detecting a bending torque applied to the bending top at the time of edgewise bending, a second process of determining whether or not a maximum value obtained by removing a torque value in starting the bending top from the bending torque is equal to or smaller than a predetermined value set in advance, and a third process of reducing a clamp load applied to a rectangular wire by the clamp when the maximum value of the bending torque is larger than the predetermined value.

Apparatus for use in the formation of a helical screw flight, the apparatus comprising: a drive first and second support heads arranged for relative axial movement with respect to one another in a direction of a main axis in response to actuation of the drive the first and second support heads being configured so as to be able to provide for a plurality of position adjustments including a lateral position adjustment whereby the first and second support heads can be displaced or moved laterally with respect to the main axis in a direction of respective lateral axes and a rotational position adjustment wherein at least one of the first and second work heads can be rotated about a rotation axis which extends in a direction generally parallel to coaxial with the main axis.