Device for printing on at least one region of the surface of an object

Abstract

A device for printing on at least one region of a surface of a so-called 3D object, for instance a curved auto body part, includes a manipulator, for instance an articulated-arm robot with six degrees of freedom. The device also includes a system for vibration compensation for the print head. The system includes an active component and a passive component. Manipulator vibration which creates defects in a printed image may thus be effectively avoided.

Claims

1. A device for printing on at least one region of a surface of an object, the device comprising: a manipulator; a print head associated with said manipulator; and a system for vibration compensation for said print head, said system including an active component and a passive component; said active component compensation for low-frequency vibration, and said passive component compensation for high-frequency vibration.

2. The device according to claim 1, wherein the low-frequency vibration includes vibration frequencies below a frequency threshold.

3. The device according to claim 1, wherein the high-frequency vibration includes vibration frequencies above a frequency threshold.

4. The device according to claim 1, wherein said active component includes an active vibration damper with a mass element and an actuator for moving said mass element.

5. The device according to claim 4, wherein said actuator is a linear motor or a plunger coil.

6. The device according to claim 1, wherein said active component is disposed on said print head or on said passive component or on said manipulator.

7. The device according to claim 1, wherein said system for vibration compensation includes at least one sensor for measuring vibration of said print head.

8. The device according to claim 7, wherein said system for vibration compensation includes a controller and an amplifier connected to said controller, said controller having an input connected to said sensor, and said amplifier having an output connected to said active component.

9. The device according to claim 1, wherein said passive component includes a connecting piece for fixing said print head to said manipulator.

10. The device according to claim 9, wherein said connecting piece is constructed as a parallelogram suspension.

11. The device according to claim 9, wherein said print head and said connecting piece together have a natural frequency being lower than a lowest natural frequency of said manipulator being relevant for a printed result.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The FIGURE of the drawing is a fragmentary, diagrammatic, sectional view of a preferred exemplary embodiment of a device for printing on an object.

DETAILED DESCRIPTION OF THE INVENTION

(2) Referring now in detail to the single FIGURE of the drawing, there is seen a preferred embodiment of a device 1 for printing on an object 2, in particular on at least one region 3 of the surface 3 of an object. The device includes a manipulator 4 which is embodied as a robot arm and which includes a connecting piece 5 and an inkjet print head 6. The print head has nozzles 7 that expel ink droplets 8 in the direction of the surface of the object. The print head is guided by the manipulator and carries out a movement 18 in strips along the surface at a printing distance.

(3) The print head 6 is connected to an end of the manipulator 4 by the connecting piece 5. The connecting piece 5 forms a passive component of the compensation system. The connecting piece is embodied as a parallelogram suspension including four bars 5a to 5d and two mounting plates 5e and 5f. The bars are disposed to form a parallelogram (as indicated by the two thicker proximal bars and the two thinner distal bars). Due to its softness, the connecting piece allows the print head to make passive compensation movements relative to the manipulator in a direction indicated by a double-headed arrow 9. The degree of softness that fits the requirements may be attained by selecting a suitable material and suitable dimensions (thickness, length).

(4) An active component 10 of the compensation system is disposed on the print head 6 in the form of a compensation module 10. The compensation module 10 includes a mass element 11 and an actuator 12. In addition, a sensor 13 is provided on the print head. The sensor may measure the acceleration of the print head, for instance. The sensor emits signals to a controller 14, which transmits the signals to an amplifier 15, which in turn transmits generated control signals to the actuator.

(5) If the actuator 12 itself has stiffness and damping properties (see reference numerals 16 and 17) or if stiffness and/or spring elements 16 or damping elements 17 are connected in parallel with the actuator 12 in a corresponding way, upon a relative movement between the mass element 11 and the print head 6, corresponding spring and damping forces are effective in parallel with the mass forces. In this case, this needs to be factored in when defining the control algorithm of the controller 14.

(6) The compensation module 10 may also be disposed on the connecting element 5 or on the manipulator 4 (see reference numerals 10 and 10).