Abstract: A friction welding method comprises causing an end surface of a first workpiece and an end surface of a second workpiece to engage in relative rotation while the end surfaces are in mutual contact as a compressive load is applied thereto so as to generate heat due to friction at a joint interface between the workpieces, thereafter stopping the relative rotation of the workpieces, and then applying an upset process pressure to the workpieces. When the workpiece end surfaces are brought into mutual contact, a compressive load employed is less than a lower threshold of a bend-producing compressive load domain within which bending of the first workpiece and/or the second workpiece would occur but the compressive load and the relative rotational speed between the workpieces are such as will cause the heat due to friction to be capable of causing plastic deformation at workpiece end surface(s).

Abstract: Provided is a method for filling a stem-side hollow area of an engine valve with metallic sodium. The method includes injecting melted metallic sodium into a cylinder having a larger diameter than an inner diameter of the hollow area of the engine valve, forming a solidified metallic sodium rod having a substantially uniform structure in the cylinder, inserting the metallic sodium into the hollow area of the engine valve through a nozzle having a small diameter, and sealing the engine valve.

Abstract: It is preferable that metallic sodium to be loaded to an engine valve used for an internal combustion engine such as automobile engine have high purity. However, conventionally, an organic solvent remaining in micropores on a surface of the metallic sodium have been hardly attracted attention. Provided is a method for purifying metallic sodium including steps of placing metallic sodium containing organic solvent in the micropores thereof in a melting tank which is sealed, and heating the melting tank under reduced pressure to vaporize and remove the organic solvent coating the metallic sodium.

Abstract: A friction welding method comprises causing an end surface of a first workpiece and an end surface of a second workpiece to engage in relative rotation while the end surfaces are in mutual contact as a compressive load is applied thereto so as to generate heat due to friction at a joint interface between the workpieces, thereafter stopping the relative rotation of the workpieces, and then applying an upset process pressure to the workpieces. When the workpiece end surfaces are brought into mutual contact, a compressive load employed is less than a lower threshold of a bend-producing compressive load domain within which bending of the first workpiece and/or the second workpiece would occur but the compressive load and the relative rotational speed between the workpieces are such as will cause the heat due to friction to be capable of causing plastic deformation at workpiece end surface(s).

Abstract: Provided is a method for filling a stem-side hollow area of an engine valve with metallic sodium. The method includes injecting melted metallic sodium into a cylinder having a larger diameter than an inner diameter of the hollow area of the engine valve, forming a solidified metallic sodium rod having a substantially uniform structure in the cylinder, inserting the metallic sodium into the hollow area of the engine valve through a nozzle having a small diameter, and sealing the engine valve.

Abstract: It is preferable that metallic sodium to be loaded to an engine valve used for an internal combustion engine such as automobile engine have high purity. However, conventionally, an organic solvent remaining in micropores on a surface of the metallic sodium have been hardly attracted attention. Provided is a method for purifying metallic sodium including steps of placing metallic sodium containing organic solvent in the micropores thereof in a melting tank which is sealed, and heating the melting tank under reduced pressure to vaporize and remove the organic solvent coating the metallic sodium.

Abstract: To provide a method of friction welding and an apparatus of friction welding in which a length of time for manufacturing one product is reduced as much as possible regardless of the dimension errors of works. The fast forwarding distance Lx1 is calculated for the fast forwarding by using the results of measuring the dimensions of works W1, W2 under the condition of the constant slowly forwarding distance Lx2, Thereby, for the work of a legitimate dimension and even for the work having a dimension smaller than the legitimate dimension, the elongation of the slowly forwarding distance is prevented compared with the work having the longer dimension than the legitimate dimension, and the relative proportion of the fast forwarding distance Lx1 is increased by making shorter the specified slowly forwarding distance.

Abstract: To provide a method of friction welding and an apparatus of friction welding in which a length of time for manufacturing one product is reduced as much as possible regardless of the dimension errors of works. The fast forwarding distance Lx1 is calculated for the fast forwarding by using the results of measuring the dimensions of works W1, W2 under the condition of the constant slowly forwarding distance Lx2, Thereby, for the work of a legitimate dimension and even for the work having a dimension smaller than the legitimate dimension, the elongation of the slowly forwarding distance is prevented compared with the work having the longer dimension than the legitimate dimension, and the relative proportion of the fast forwarding distance Lx1 is increased by making shorter the specified slowly forwarding distance.

Abstract: A burring apparatus for a friction welding machine comprises a clamp unit provided at the front end of a horizontal main spindle, for holding work piece W1 coaxial with the main spindle, a clamp unit provided at the front end of a slide movable to and away from the main spindle in the direction of the axis of the main spindle and a doughnut-shaped cutter for shearing off a burr. Work piece W2 is moved forward together with the slide until work piece W2 comes into contact with work piece W1 so that the mated ends of work pieces W1 and W2 are friction welded together to form a joint work piece W. The burr formed on the jointed work piece W is sheared off by the cutter. The jointed work piece W is then liberated from the main spindle.

Abstract: A burring apparatus for a friction welding machine comprises a clamp unit provided at the front end of a horizontal main spindle, for holding work piece W1 coaxial with the main spindle, a clamp unit provided at the front end of a slide movable to and away from the main spindle in the direction of the axis of the main spindle and a doughnut-shaped cutter for shearing off a burr. Work piece W2 is moved forward together with the slide until work piece W2 comes into contact with work piece W1 so that the mated ends of work pieces W1 and W2 are friction welded together to form a joint work piece W. The burr formed on the jointed work piece W is sheared off by the cutter. The jointed work piece W is then liberated from the main spindle.