US 12,083,582 B2
Hold-down device for a process during stamping and/or riveting
Bert Brahmer, Bruchsal (DE)
Assigned to Voith Patent GmbH, Heidenheim (DE)
Filed by Voith Patent GmbH, Heidenheim (DE)
Filed on Feb. 18, 2022, as Appl. No. 17/651,777.
Application 17/651,777 is a continuation of application No. PCT/EP2020/073082, filed on Aug. 18, 2020.
Claims priority of application No. 10 2019 122 276.1 (DE), filed on Aug. 20, 2019.
Prior Publication US 2022/0168801 A1, Jun. 2, 2022
Int. Cl. B21J 15/28 (2006.01); B21J 15/02 (2006.01); B21J 15/20 (2006.01)
CPC B21J 15/28 (2013.01) [B21J 15/025 (2013.01); B21J 15/20 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A joining device to produce a punch/riveting connection, the joining device comprising:
a joining drive, the joining drive including:
a hydraulic unit;
an axially movable piston rod; and
a hold-down device, the hold-down device including:
a hold-down cylinder, which is configured for moving axially in order to provide a hold-down force to a workpiece;
a pressure chamber to provide the hold-down force and/or a position of the hold-down device, the hold-down cylinder at least partially defining the pressure chamber, which is configured for at least partially holding a hydraulic fluid therein; and
a pressure accumulator, wherein the pressure chamber is continuously hydraulically connected to the pressure accumulator during a joining operation to produce the punch/riveting connection; and
a differential cylinder with a piston chamber and an annular chamber to drive the axially movable piston rod, wherein the hydraulic unit includes a pump with reversible delivery direction, the pump being a 4-quadrant pump.