GB1432118A - Lattice welding machines - Google Patents

Abstract

1432118 Variabfe-speed ratchet gear EVG ENTWICKLUNGS U VERTWERTUNGS GmbH 23 May 1974 [30 May 1973] 23136/74 Heading F2D Intermittent rotary motion is imparted to a shaft 13 by either of a pair of linkages each comprising a bar 7, 8, Fig. 2, pivotally connected at one end 5a, 6a to a curved arm 3 oscillated about a fixed pivot 4 by a to-and-fro mechanism, e.g. a crank 1 and connecting rod 2, and at the other end 9a, 10a to a respective member 9, 10 rotatable on the shaft 13 and carrying means such as pawls 11, 12 engageable with a toothed wheel 14 secured to the shaft. The arrangement is such that when the crank 1 is displaced 180 degrees from the position shown the two pivots 9a, 10a are in alignment with each other at a point which lies at the centre of an arc which passes through the pivots 4, 5a, 6a so that brackets 5, 6 may be adjusted on the arm 3, which may have calibrations, to vary the transmission ratio of each linkage without moving the members 9, 10. Either of pawls 11, 12 is selectively movable into contact with the toothed wheel by means (not shown) such as a fluid-operated piston or a cam lever mechanism. Reverse movement of the wheel 14 is prevented by a spring-loaded pawl 15. The apparatus is for use in a welding machine for continuous reinforcement mat for concrete, the shaft 13 operating a conveyer by which the mat is advanced, and the selection of the transmission linkages being programmed so that transverse reinforcement rods are positioned at closer intervals where the mat is to be cut. More than two members 9, 10 may be employed, in which case each member or pair of members may have its own wheel 14. The brackets 5, 6 may be mounted on adjacent slideways so that they do not interfere with each other when adjusted close together. In a modification, a wheel 29, Fig. 6, fixed to the shaft 13 is flanked by discs 9, 10 in place of the members 9, 10 of Fig. 2, and the transmission ratio is selected by a clutch member 28 slidable on peripheral teeth on the wheel and having toothed rings 26, 27 for co-operation with toothed rings 24, 25 on the discs. A further modification is referred to employing a programmed electromagnetic clutch for transmission ratio selection.