Abstract: An armature support pivotally supports an armature at one end thereof with the armature holding a print wire, wherein the armature support comprises a support member having a pair of arms; through holes formed in the pair of arms and having the same axis, and a penetrating hole formed in a base portion of the armature. The axis of the penetrating hole coincides with the axis of the through holes when the base portion of the armature is disposed between the pair of arms. A torsion spring member comprising a pair of larger diameter end portions, a larger diameter center portion and a pair of smaller diameter portions which interconnect the larger diameter end portions to the larger diameter center portion is disposed with the larger diameter end portions in the through holes and the larger diameter center portion being disposed in the penetrating hole, whereby the spring member is connected to the support member and armature at the larger diameter end and center portions.

Abstract: A print head for dot printers comprising a plurality of actuators each including an armature supported on a holder through a torsion spring and having at its end a printing wire. The torsion spring is inserted in and bonded to the inner wall of through-holes of the bifurcated end portion of one of the armature and holder and to the inner wall of through-hole of the other of them, and has larger diameter portions fitted in the through-holes and smaller diameter portions interposed between the larger diameter portions. The smaller diameter portions of the torsion spring are formed in the concave section to avoid the concentration of torsional stress in the stepped boundary portions.

Abstract: The print head has armatures each provided with a holding part connected to one end of a spring plate. For avoiding concentration of a tensile stress on a brazed part between the holding part and the spring plate, part of the holding part extending contiguously to one side of the spring plate, subjected to a compressive stress when the spring is bent, is longer than the part of the holding part extending contiguously to the other side of the spring plate subjected to a tensile stress when the spring plate is bent.

Abstract: A print head for impact type dot matrix printer having means for air-cooling the interior of the print head elevated in temperature due to the generation of heat of solenoid coils, the air cooling means is constituted in such a manner that the outer face of the print head along the direction of movement thereof is formed so as to cause the faster flow of air along said outer face when the print head is moved, and said outer face is provided with ventilating hole means which communicates the interior of the print head and the outside. When the print head is moved, it causes the faster flow along said outer face to thereby draw the air from the interior of the print head through the ventilating hole means due to the difference in pressure.

Abstract: A copper alloy which is high in strength and electroconductivity is manufactured by casting, without chill casting, a copper alloy mass substantially consisting of copper and containing 0.2 to 1.5% by weight of chromium and 0.01 to 0.5% by weight of tin, hot working the cast copper alloy mass, then cooling, not slowly, the hot worked alloy mass without being subjected to any solid solution treatment, further cold working the cooled alloy mass, and thereafter subjecting the cold worked alloy mass to an aging treatment.

Abstract: An armature support device for rotatably supporting, in a print head, one end of an armature which holds a print wire at the other end thereof. The support device comprises a support member and a spring member. The spring member is made of a piece of a resilient wire, including a fixed portion of a hair pin shape to be secured to the armature, a pair of arm portions extending oppositely on the same axis from both ends of the fixed portion for functioning as a rotational fulcrum for the armature, a pair of leg portions further extending, by being perpendicularly bent, from both ends of the arm portions for being firmly fixed to the support member. The armature is biased toward a predetermined position by torsional resilient force of the arm portions of the spring member, and it is rotated about the arm portions by an electromagnetic device twisting the same to advance or restore the print wire.

Abstract: A print head for a serial dot-printer which includes improved structure to fix each print wire to a pivotable armature. The armature is provided with an arm portion which is made of a stainless steel plate and consists of a pair of mutually opposed side portions and a connecting portion connecting the side portions. Inner surfaces of the front areas of the side portions are welded to each other at the free end portion of the arm. A first supporting full 360.degree. aperture is thus formed between the welded side portions perpendicular to the longitudinal direction of the armature, and a second print wire supporting aperture is formed in the connecting portion and is spaced by a predetermined distance from the first supporting aperture. The rear end of the print wire is inserted through the first supporting aperture until it reaches the second supporting aperture where it is welded to the internal surface of the second supporting aperture in the connecting portion.

Abstract: A print head for use in a dot-matrix printer consisting of a plurality of print wires, a guide member with a nose portion for guiding the print wires, a plurality of armatures, an armature support member for supporting one end of the armatures corresponding to each of the print wires, and an armature drive device having a magnetic member with electromagnets respectively corresponding to the armatures. The guide member, the armature support member and the magnetic member are firmly connected in that order by a hollow cylindrical connecting member which fits on the connected members from the side of the last member. The front end of the connecting member is secured by laser welding or the like to the periphery of the guide member, and a plurality of resilient tongues formed on the rear end thereof are engaged with the magnetic member to bias the magnetic member and the armature support member toward the guide member.