Patent ID: 7926157
Filing Date: 2011-04-19
Classification: B21J,Y10T

Abstract:
1. A hydro-pneumatically operated riveting tool for installing a rivet, including hydraulically driven gripping means for gripping and pulling a stem of the rivet, thereby to place the rivet, a hydraulic supply comprising a hydraulic inlet port for supplying hydraulic fluid to drive the gripping means, a sealing region around the inlet port, and return means for returning the gripping means back to a rest position again after placing a rivet; the hydraulic supply for the gripping means including a unidirectional flow restriction arranged to provide a restricted flow of hydraulic fluid during pulling of the stem and to provide relatively free flow during return of the gripping means to the rest position, the unidirectional flow restriction comprising a moveable member located in a path of the hydraulic flow adjacent the inlet port which is arranged to have limited reciprocal movement in a direction of hydraulic flow towards and away from the inlet port into a sealing and non-sealing position, the moveable member having an inner surface which cooperates with the sealing region around the inlet port to form a seal which substantially prevents flow of hydraulic fluid around a periphery of the moveable member when the member is pushed by hydraulic flow into the sealing position, the moveable member including a member inlet and a member outlet, and an aperture of relatively small cross-sectional flow area through which hydraulic fluid is permitted to flow when the moveable member is in the sealing position, the moveable member being arranged to diffuse or direct hydraulic flow through the aperture away from components which are in the vicinity of the inlet port; wherein the member outlet has a smaller cross-sectional area than the member inlet so that as fluid transitions from the member inlet to the member outlet, the velocity of the hydraulic fluid is reduced.