Abstract: In an air actuated down-the-hole hammer for rock drilling, a piston reciprocates within a casing to impact against a rear anvil surface of a drill bit. A foot valve extends axially between the piston and the drill bit. The anvil surface is inclined downwardly in a radially outward direction to cause liquid on the anvil surface to be discharged in a direction away from the foot valve, to prevent damage to the foot valve which could occur if piston impacts were able to create high-speed liquid streams contacting the foot valve.

Abstract: Apparatus for folding sheet blanks (1), e.g. for boxes and trays from carton or corrugated cardboard. It includes press means (6, 7) attached to at least one endless conveying means (10). The press means are intended to coact with selected parts (2, 3) of the blanks for folding them up or down from the plane of the blank during their passage through the apparatus. The blanks are arranged to be conveyed through the apparatus at the same speed as that at which the conveying means is driven. The latter is guided in a helical path by an elongate, rigid structure (8, 9) forming continuous support for the conveying means. During the entire folding operation the operative ones of the press means attached to the conveying means press against the same area on the part of the blank with which they coact.

Abstract: A percussion drill bit for drilling bores, comprises a drill body having a plurality of gauge row inserts embedded in a front end of the drill body. Each gauge row insert comprises a cemented carbide body having a mounting portion embedded in the drill body, and a front end protruding from the drill body. A polycrystalline diamond layer is provided on the front end of the carbide body. The diamond layer has a rear edge disposed in the vicinity of a maximum diameter of the insert. That rear edge is spaced from the wall of the bore during drilling by tilting the gauge row insert at an acute angle of 41.degree. to 51.degree. relative to the rotational axis of the drill bit. The front end of the carbide body is defined by a radius whose origin lies on a center axis of the insert. That origin is disposed axially rearwardly of a plane containing the rear edge of the diamond layer. The length of that radius is 50% to 52% of a diameter of the mounting portion of the insert.