Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
  • B30B15/16—Control arrangements for fluid-driven presses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
  • B30B15/16—Control arrangements for fluid-driven presses
  • B30B15/161—Control arrangements for fluid-driven presses controlling the ram speed and ram pressure, e.g. fast approach speed at low pressure, low pressing speed at high pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03C—POSITIVE-DISPLACEMENT ENGINES DRIVEN BY LIQUIDS
  • F03C1/00—Reciprocating-piston liquid engines
  • F03C1/007—Reciprocating-piston liquid engines with single cylinder, double-acting piston
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
  • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
  • F15B11/022—Systems essentially incorporating special features for controlling the speed or actuating force of an output member in which a rapid approach stroke is followed by a slower, high-force working stroke
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
  • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
  • F15B11/024—Systems essentially incorporating special features for controlling the speed or actuating force of an output member by means of differential connection of the servomotor lines, e.g. regenerative circuits
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
  • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
  • F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
  • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
  • F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
  • F15B11/036—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force by means of servomotors having a plurality of working chambers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
  • F15B2211/205—Systems with pumps
  • F15B2211/20576—Systems with pumps with multiple pumps
  • F15B2211/20592—Combinations of pumps for supplying high and low pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/30—Directional control
  • F15B2211/31—Directional control characterised by the positions of the valve element
  • F15B2211/3122—Special positions other than the pump port being connected to working ports or the working ports being connected to the return line
  • F15B2211/3133—Regenerative position connecting the working ports or connecting the working ports to the pump, e.g. for high-speed approach stroke
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/60—Circuit components or control therefor
  • F15B2211/665—Methods of control using electronic components
  • F15B2211/6653—Pressure control

Definitions

• the invention relates to a hydraulic drive for a punching or forming machine according to the preamble of claim 1.
• Such hydraulic drives for punching or forming machines have a working cylinder designed as a differential cylinder, via which a punching tool is actuated.
• a circuit diagram of a known, but not described in a document solution of such a hydraulic drive is shown in Figure 1.
• a working cylinder 2 is subdivided by a piston 4 into a cylinder space 6 on the piston bottom end and an annular space 8 on the piston rod side.
• the cylinder chamber 6 is supplied with pressure medium via a continuously adjustable valve 10.
• An input port E of the continuously adjustable valve 10 is connected to a valve arrangement 12.
• the valve arrangement 12 has an unlockable check valve 14 and an oppositely blocking check valve 16 connected in parallel with it.
• the unlockable check valve 14 can be unlocked via a predetermined load pressure in the cylinder chamber 6. It is connected to an inlet line 28
• High pressure accumulator HD connected.
• the check valve 16 is connected via an inlet line 32 to a low-pressure accumulator ND.
• the annular space 8 is constantly connected to the low-pressure accumulator ND.
• the continuously adjustable valve 10 and the valve arrangement 12 are in the basic positions shown.
• Low pressure is applied to the cylinder chamber 6, so that the piston 4 moves out quickly due to its area difference.
• This load pressure is reported to the unlockable check valve 14. Above a certain load pressure, this acts as a switching pressure and the check valve 14 is unlocked. Consequently, the high pressure accumulator HD is switched on.
• the high pressure is directed to the inlet port E and thus into the cylinder chamber 6, so that a maximum punching force can be applied.
• the high pressure is also present at the check valve 16, so that it closes and the pressure medium connection to the low pressure accumulator ND is shut off. After punching, the load pressure in the cylinder chamber 6 drops, as a result of which the unlockable check valve 14 returns to its basic position and the low-pressure accumulator ND is switched on.
• a disadvantage of this known solution is that the check valve in the low-pressure line only closes by means of a time delay of 2 ms to 5 ms, so that the pressure medium subjected to high pressure flows out via the check valve to the low-pressure accumulator. With lifting times of approximately 10ms to 20ms for the extension of the working cylinder, there is a considerable loss of time and energy.
• the drive unit has a working cylinder with a piston that separates an annular space from a cylinder space.
• the annulus acts in the direction of retraction and the cylinder space acts in the direction of extension on the piston.
• the cylinder chamber can be acted upon with high pressure, low pressure or with a tank pressure by means of a motor-adjustable valve arrangement with two control slides of two control valves that are in mechanical operative engagement with one another.
• the annulus is constantly subjected to low pressure.
• the control slides are in contact with each other at the end and are biased into their basic positions by means of a spring.
• a cam disk acting on one of the control slide is controlled via an electric motor such that the control slide is transferred from its basic positions into control positions depending on the rotation of the cam disk.
• Low pressure is applied to the cylinder chamber to quickly extend the piston. Due to the difference in area of the piston, it extends until it hits a workpiece to be machined.
• High pressure is applied to the cylinder chamber to apply a high punching force.
• the cylinder space to the tank is relieved of pressure, so that the piston is moved back to its starting position due to the low pressure acting in the annular space.
• a disadvantage of this solution is that the valve arrangement with the two control slides in contact with one another and the motorized control is designed to be complex in terms of device technology.
• the object of the present invention is to provide a hydraulic drive for a punching or forming machine in which no significant time and energy losses occur when the pressure is switched.
• the drive unit has a working cylinder, the piston of which acts directly or indirectly on a workpiece to be machined. At least one pressure chamber of the working cylinder can be pressurized with a tank pressure or a supply pressure via a continuously adjustable valve to retract and extend the piston. Furthermore, a valve arrangement is provided which is connected upstream of the continuously adjustable valve and via which an input connection of the continuously adjustable valve can be acted upon with a higher or lower supply pressure. According to the invention, the valve arrangement has a switching valve which, depending on the load pressure on the working cylinder, can be switched between a basic position and a switching position in order to tap the supply pressure from a low-pressure source or a high-pressure source.
• the working cylinder has a cylinder space and an annular space.
• the pressure in the cylinder chamber acts in the direction of extension, and the pressure in the annulus acts on the piston in the direction of retraction. Furthermore, the pressure in the cylinder chamber acts on a large control surface of the switching valve and forms the switching pressure for switching the switching valve into its switching position from a certain load pressure, the pressure in the annular space acting in the opposite direction on a small control surface of the switching valve.
• a pilot valve is provided, via which the small control surface of the switching valve which is effective in the direction of the basic position can be relieved, so that the switching valve can be switched over and the high pressure can be conducted to the cylinder chamber when the load pressure in the cylinder chamber is reduced.
• the pilot valve is preferably actuated electrically.
• the annular space can be constantly subjected to high pressure.
• the annular space is preferably continuously connected to the low-pressure source, since the annular area is then larger and can be subjected to a higher load as a stop.
• the working cylinder can have two or three pressure chambers.
• Other advantageous embodiments of the invention are the subject of further dependent claims.
• Figure 1 is a circuit diagram of a known solution of a hydraulic drive for a nibbling machine
• Figure 2 is a circuit diagram of a preferred solution according to the invention of a hydraulic drive for a nibbling machine.
• FIG. 2 shows a greatly simplified circuit diagram of a drive 1 of a high-speed nibbling machine. With such nibbling machines, the extension movement takes place within 10 ms to 20 ms.
• the nibbling machine has a working cylinder 2 which, as in the known solution described at the outset, has a piston 4 which separates a cylinder space 6 from an annular space 8 and acts directly or indirectly on a punching tool.
• the piston 4 has a piston rod 18 on the rear, which extends away from the piston head and passes through the working cylinder 2 at the end.
• the cylinder chamber 6 is connected to a working connection A of a continuously adjustable valve 10 which, in one of its control positions (b), opens a connection between the cylinder chamber 6 and a tank line 20 connected to a tank.
• a tank line damper 22 and a preload valve 24 are arranged in the tank line 20. Pressure fluctuations in the tank line 20 are suppressed by the tank line damper 22 and the tank line 20 is opened by the preload valve 24 biased a pressure equivalent to the spring of the biasing valve 22.
• An input port P of the continuously adjustable valve 12 is one with a working port B.
• (1), (2) of the switching valve 26 is connected to a pressure port P or a pressure port P 'of the switching valve 26.
• the pressure connection P is connected to a high-pressure accumulator HD via an inlet line 28, and the pressure connection P 'is connected to a low-pressure accumulator ND via a branch line 30 and a section of an inlet line 32.
• the inlet line 32 connects the low-pressure accumulator ND to the annular space 8.
• the pressure in the annular space 8 is tapped via a control line 34 and an electrically operated pilot valve 38.
• the pressure In the basic position (x) of the pilot valve 38, the pressure is guided to a small control surface of the switching valve 26 which is effective in the direction of the basic position (1) of the switching valve 26.
• a control position (y) of the pilot valve 38 In a control position (y) of the pilot valve 38, the connection to the small control surface is blocked and a connection of the small control surface to the tank T is opened.
• the pressure in the cylinder chamber 6 is tapped via a control line 36 and led to a large control surface of the switching valve 26 which is effective in the direction of the switching position (2).
• the switching valve 26 is in its basic position shown (1).
• the pilot valve 34 is in its basic position (x) and in
• Annulus 8 effective pressure becomes a small control area of the switching valve 26 out.
• the continuously adjustable valve 10 is in its basic position (a) shown.
• the cylinder chamber 6 is thus subjected to low pressure.
• the annular space 8 is also supplied with low pressure via the inlet line 32, so that the piston 4 extends due to its area difference, pressure medium being displaced from the annular space 8 into the low-pressure accumulator ND.
• the load pressure in the cylinder space 6 increases.
• this acts as a changeover pressure and the switching valve 26 is brought into its switching position (2) against the force of a return spring and a force that corresponds to the pressure acting on the small control surface, in which the working port B with the pressure port P is connected so that high pressure acts on the piston crown surface and thus the punching force applied by the working cylinder 2 is increased.
• the load pressure drops and the switching valve 26 switches back to its basic position (1), in which the pressure port P is shut off and the pressure port P 'is opened, so that the working port B is again at low pressure.
• the continuously adjustable valve 10 is transferred to its control positions marked with (b), in which the cylinder chamber 6 is connected to the tank T. Due to the low pressure acting in the annular space 8, the piston 4 is pushed back into its starting position.
• pilot valve 38 can be in its control position as an option during the rapid feed
• the solution according to the invention with a switching valve 26 connected upstream of the continuously adjustable valve 10 can also be used in other cylinder constructions, for example with three pressure chambers.
• a hydraulic drive for a punching or forming machine with a working cylinder having a plurality of pressure chambers, the piston of which acts directly or indirectly on a workpiece to be machined, with at least one pressure chamber of the working cylinder for retracting or extending the piston via a continuously adjustable valve with a Tank pressure or a supply pressure can be acted upon, and with a valve arrangement which is connected upstream of the continuously adjustable valve and via which an input connection of the continuously adjustable valve can be acted upon with a higher or lower supply pressure, the valve arrangement having a switching valve which, depending on the load pressure on Working cylinder between a basic position and a switching position is switchable to tap the supply pressure from a low pressure source or a high pressure source.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Combustion & Propulsion (AREA)
• Chemical & Material Sciences (AREA)
• Control Of Presses (AREA)
• Fluid-Pressure Circuits (AREA)
• Press Drives And Press Lines (AREA)
• Fluid-Driven Valves (AREA)
• Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)
• Multiple-Way Valves (AREA)
• Valve Device For Special Equipments (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=33420017

Family Applications (1)

Country Status (6)

Families Citing this family (13)

Family Cites Families (4)

• 2004
  • 2004-05-14 US US10/557,023 patent/US7370569B2/en not_active Expired - Fee Related
  • 2004-05-14 DE DE502004006585T patent/DE502004006585D1/de not_active Expired - Fee Related
  • 2004-05-14 DE DE102004024126A patent/DE102004024126A1/de not_active Withdrawn
  • 2004-05-14 AT AT04732933T patent/ATE389530T1/de not_active IP Right Cessation
  • 2004-05-14 JP JP2006529598A patent/JP2007502213A/ja active Pending
  • 2004-05-14 EP EP04732933A patent/EP1625011B1/fr not_active Expired - Lifetime
  • 2004-05-14 WO PCT/DE2004/001014 patent/WO2004103692A1/fr active IP Right Grant

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events