Multi-step joining device and joining method therefor

A joining device, comprising:

• a punch with which a linear, nonrotating setting movement can be executed,
• a clamping device with which one or more components can be compressed in a joining direction, and with
• a drive unit that operates in at least two steps with which the punch and the clamping device can be moved, and that can be switched over depending on a force that can be applied by the punch and/or the clamping device, and/or depending on a realizable punch path, and/or a clamping device path, and/or a joining time and/or an electrical motor current of a pump, wherein the drive unit has:
• a. an at least two-step electrical spindle drive in which a gear unit converts a rotary movement of an electric motor into a linear setting movement of the punch by at least two switchable different transmission steps, or two spindles with different thread pitch, wherein the respective linear setting movement of the at least two switchable different transmission steps differs in terms of possible setting paths per unit time and/or in terms of an applicable punch force, and at least the electric motor, the gear unit which is switchable and the at least two-step electrical spindle drive form a single operating module, or
• b. an at least two-step hydraulic punch drive with a dual-acting cylinder having a one-sided piston rod, a hydraulic reservoir, an electric motor connected to a first and a second step of a hydraulic pump and a valve block which together form a single operating module, in the first step of which a high volumetric flow with a low hydraulic pressure in comparison to the second step can be provided, and in the second step of which a low volumetric flow with high hydraulic pressure can be provided, or
• c. an at least two-step hydraulic punch drive with a dual-acting cylinder having a one-sided piston rod, a hydraulic reservoir, an electric motor connected to a hydraulic pump and a valve block which together form a single operating module, the dual-acting cylinder being operable as a differential cylinder by the valve block so that, in a first step of the at least two-step hydraulic punch drive, a high volumetric flow with a low hydraulic pressure in comparison to a second step of the at least two-step hydraulic punch drive can be provided, and in the second step of the at least two-step hydraulic punch drive, a lower volumetric flow with high hydraulic pressure can be provided,
• in which furthermore the following is provided:
• at least one load sensor so that a mechanical load on the punch and the clamping device in the joining direction can be detected, and
• a path transducer so that the punch path and/or the clamping device path can be detected, and/or
• a time recorder so that a joining time can be detected, wherein
• the clamping device can be moved by the punch so that the mechanical load on the clamping device or on the one or more components can be detected by the at least one load sensor, while the clamping device can be pretensioned by at least one first spring by a movement of the punch against the one or more components, wherein
• reaching at least one first threshold value of the mechanical load on the punch and/or the clamping device is discernible by at least one control unit by itself or in combination with the at least one load sensor, or
• reaching at least one first threshold value of the punch path can be recognized by at least one control unit by itself or in combination with the path transducer, or reaching at least one first threshold value of the joining time is discernible by at least one control unit by itself or in combination with the time recorder, after which the drive unit that operates in at least two steps is switchable by the at least one control unit between the at least two steps that comprise at least one movement step and at least one power step, of which the at least one movement step is distinguished by a faster punch speed in comparison to the at least one power step, and the at least one power step is distinguished by a greater applicable punch force in comparison to the at least one movement step.