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EP-4644053-B1 - METHOD FOR HANDLING AN OBJECT BY MEANS OF A GRIPPING DEVICE AND HANDLING DEVICE FOR CARRYING OUT THE METHOD

EP4644053B1EP 4644053 B1EP4644053 B1EP 4644053B1EP-4644053-B1

Inventors

  • STOCKBURGER, RALF
  • Schmider, Matthias

Dates

Publication Date
20260513
Application Date
20240430

Claims (14)

  1. Method for handling an object (88) by means of a gripping apparatus (10), in particular a vacuum gripping apparatus, comprising a gripper main body (12), and at least one gripping unit (14) held on the gripper main body, the gripping unit comprising a piston (16) and a gripper (18), in particular a vacuum gripper (28), that is motion-coupled to the piston (16) for gripping the object (88), the piston (16) being displaceable relative to the gripper main body (12) along a stroke axis (20) between an axially retracted configuration and an axially extended configuration in an extension direction (22) and in a retraction direction (24) which is opposite to the extension direction, the piston (16) being extendable in the extension direction (22) by the application of compressed air, the method comprising: - applying an extension pressure to the piston (16) so that the piston (16) is extended in the extension direction (22) starting from the retracted configuration; - placing the gripper (18) that is motion-coupled to the extended piston (16) onto the object (88) to be gripped; - gripping the object (88) using the gripper (18), in particular suctioning the object (88) using the vacuum gripper (28), characterized in that the piston (16) is subjected to a presetting pressure when the gripper (18) the gripper is placed and is subjected to a main pressure after placement, in particular after gripping, the presetting pressure being lower than the main pressure.
  2. Method according to claim 1, wherein the main pressure is selected such that the piston (16) is transferred into the extended configuration and/or held in the extended configuration by the application of the main pressure.
  3. Method according to claim 1 or claim 2, wherein the presetting pressure is at most half as great as the main pressure.
  4. Method according to any of the preceding claims, wherein the presetting pressure corresponds to the ambient pressure.
  5. Method according to any of the preceding claims, wherein the presetting pressure is between 0 and 2 bar and/or wherein the main pressure is between 4 and 6 bar, in particular between 4.5 and 5.5 bar.
  6. Method according to any of the preceding claims, wherein the piston (16) is spring-loaded in the retraction direction (24), in particular into the retracted configuration, wherein the presetting pressure is selected such that, when freely extended, counter to the spring load, the piston (16) is transferred into the extended configuration or into an intermediate position between the retracted configuration and the extended configuration.
  7. Method according to any of the preceding claims, wherein the extension pressure is greater than the presetting pressure, in particular corresponds to the main pressure.
  8. Method according to any of the preceding claims, wherein the placement is carried out such that the piston (16) is displaced in the retraction direction (24) during placement, counter to the application of the presetting pressure.
  9. Method according to any of the preceding claims, wherein a sensor device is provided for monitoring a gripping state of the gripper (18), wherein a gripping state of the gripper is monitored by means of the sensor device, and the pressure acting upon the piston is changed depending on an output signal of the sensor device, in particular the pressure acting upon the piston (16) is increased from the presetting pressure to the main pressure upon detection of the gripping of an object by the gripper (18).
  10. Method according to any of the preceding claims, wherein the gripper (18) is in the form of a vacuum gripper (28) which delimits a vacuum chamber (34) that is open by means of a vacuum opening (32), wherein a sensor device is also provided for monitoring a negative pressure prevailing in the vacuum chamber (34), wherein, during the placement, the negative pressure prevailing in the vacuum chamber (34) is monitored by means of the sensor device, wherein, when a pressure threshold value is exceeded or not met, the pressure acting upon the piston is increased from the presetting pressure to the main pressure.
  11. Handling apparatus for carrying out a method according to any of the preceding claims, comprising - a gripping apparatus (10) comprising a gripper main body (12) and at least one gripping unit (14) held on the gripper main body, the gripping unit comprising a piston (16) and a gripper (18) that is motion-coupled to the piston (16) for gripping the object (88), wherein the piston (16) is displaceable relative to the gripper main body (12) along a stroke axis (20) between an axially retracted configuration and an axially extended configuration in an extension direction (22) and in a retraction direction (24) which is opposite to the extension direction, wherein the gripping unit (14) comprises a gripping unit housing (44) in which the piston (16) is displaceable, wherein a pressure chamber (62) is formed in the gripping unit housing (44), which fluidically interacts with the piston (16) such that, by the application of compressed air to the pressure chamber (62), a force acting in the extension direction (22) is exerted on the piston (16), - a compressed-air supply device for supplying the pressure chamber (62) with compressed air; - a pressure adjustment device for adjusting a supply pressure of the compressed air; - optionally, a manipulator for displacing the gripping apparatus (10), and - a control device for controlling the handling apparatus (10), wherein the control device is configured to carry out the method according to any of claims 1 to 9.
  12. Handling apparatus according to the preceding claim, wherein the gripper (18) is in the form of a vacuum gripper (28), in particular wherein the vacuum gripper (28) can be supplied with negative pressure via the piston (16) connected thereto.
  13. Handling apparatus according to the preceding claim, wherein the vacuum gripper (28) delimits a vacuum chamber (34) that is open by means of a vacuum opening (32), wherein a sensor device that interacts with the control device is also provided for monitoring a negative pressure prevailing in the vacuum chamber (34), wherein the control device is configured to actuate the sensor device such that it monitors the negative pressure prevailing in the vacuum chamber (34) during the placement of the vacuum gripper (28) on the object (88) to be gripped, wherein the control device is also configured, when a pressure threshold value in the vacuum chamber is exceeded or not met, to actuate the pressure adjustment device such that it increases the pressure acting upon the pressure chamber (62) from the presetting pressure to the main pressure.
  14. Handling apparatus according to any of claims 12 or 13, wherein the gripping apparatus (10) has, in particular on the gripper main body (12), a vacuum connection (40) for connection to a negative pressure supply device, wherein the gripping unit is designed such that, in the extended configuration of the piston (16), a flow connection is established between the vacuum connection (40) and the vacuum gripper (28), and, in the retracted configuration of the piston (16), this flow connection is shut off.

Description

The invention relates to a method for handling an object by means of a gripping device, which has at least one gripping unit mounted on a gripper base. The gripping unit comprises a piston and a gripper coupled to the piston, wherein the piston is adjustable along a stroke axis between an axially retracted configuration and an axially extended configuration. The invention also relates to a handling device comprising such a gripping device. Such gripping devices are from the prior art. DE 20 2017 106859 U1 , IT 2022 0001 9074 A1 , EP 4147 831 A1 , US 2022/189122 A1 and DE 10 2017 218877 A1 known. To grip an object, at least one piston is moved from its retracted position into the The extended configuration is transferred, and then the gripper, which is coupled to the piston's movement, is placed on the object to be grasped, and the object is gripped. The piston is typically extended by applying compressed air to it. The invention addresses the problem of designing a robust and flexible gripping device. Furthermore, it is desirable to be able to reliably grip objects with irregular surfaces and/or shapes. This problem is solved according to the invention by a method with the features of claim 1. This method is for handling an object by means of a gripping device comprising a gripper base and at least one gripping unit, preferably several gripping units, held on the gripper base. The method is therefore also a method for operating such a gripping device. The gripping unit (or each gripping unit in the case of multiple gripping units) comprises a piston and a gripper, in particular a suction gripper, coupled to the piston's movement for gripping the object. The piston is adjustable along a stroke axis between an axially retracted configuration and an axially extended configuration relative to the gripper body. The piston is adjustable in an extension direction and in a direction relative to the The piston's extension direction is adjustable along the stroke axis in the opposite direction to the retraction direction. The retracted and extended configurations of the piston represent, in particular, the end positions of the piston's displacement along the stroke axis. The piston can be actuated, for example, by a spring, especially in the retracted position. The piston can be extended in the extension direction by applying compressed air, in particular from the retracted configuration to the extended configuration. According to the procedure, the piston of the gripping unit (or, in the case of multiple gripping units, the piston of at least one gripping unit) is first pressurized with compressed air at an extension pressure, so that the piston is extended from its retracted position in the extension direction. In particular, the gripper can be activated by extending the piston. The gripper, which is coupled to the movement of the extended piston, is then placed on the object to be gripped, e.g. by means of a manipulator, in particular a robot. The object is then grasped with the gripper. If the gripper is designed as a suction gripper, the grasping action can, for example, include suctioning the object into place. The gripping action can begin instantly upon placement. or include a time interval after setup. According to the invention, the piston is pressurized with compressed air at a preset pressure upon contact and, after contact, particularly after gripping, is pressurized with compressed air at a main pressure, wherein the preset pressure is lower than the main pressure. Thus, after contact, particularly after gripping, the pressure acting on the piston is increased. By pressurizing the piston with the preset pressure or the main pressure, the piston is acted upon in the extension direction, particularly against an optional spring-loaded action in the retraction direction. In the proposed method, at least one piston is subjected to reduced pressure upon contact, allowing it to yield slightly in the insertion direction ("springing"). In other words, the proposed method facilitates a gentle contact of the gripper with the object, reducing the risk of damage to the gripper and/or the object. Furthermore, the springing of the piston compensates for any unevenness on the component surface (higher tolerance), thus promoting reliable gripping, particularly a reliable seal when the gripper is configured as a suction gripper. After being placed on the ground, the piston is then brought into a stable position by being subjected to the higher main pressure. The configuration (especially the piston in its extended position) is transferred so that the object is held in a defined position on the gripping device. This facilitates reliable and precise handling of the object. One exemplary implementation of the gripping unit provides that the piston is slidable within a gripping unit housing, and that a pressure chamber is formed within the gripping unit housing. This pressure chamber interacts fluidically with the piston