Device for processing workpieces using ultrasound

Abstract

The invention concerns a device for processing workpieces using ultrasound, comprising an ultrasound sonotrode and an anvil, wherein a workpiece is processed between the ultrasound sonotrode and the anvil, the ultrasound sonotrode having a recess with open edges in the axial direction and a die is disposed in the recess in the direction towards the workpiece and/or the anvil, the die being displaceable between a rest position retracted into the ultrasound sonotrode and an operating position in which it partially projects out of the ultrasound sonotrode.

Description

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a longitudinal section through the inventive device before disposition onto a workpiece;

FIG. 2 shows the device in accordance with FIG. 1 during disposition onto the workpiece; and

FIG. 3 shows the device in accordance with FIG. 1 during processing of the workpiece.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a device, designated in total with reference numeral 10, for processing a workpiece 12, having a booster or converter 14, an ultrasound sonotrode 16 and with an anvil 18, which is fixed to an indicated machine frame 20. The booster 14, the ultrasound sonotrode 16, the workpiece 12 and the anvil 18 are disposed along an axis 22, in particular, the longitudinal axis of the ultrasound sonotrode 16, which also represents the processing direction. The ultrasound sonotrode 16 has a front end 24 which represents the processing surface or welding surface 26 and which faces the workpiece 12.

The ultrasound sonotrode 16 has a recess which is designated in total with 28, and is designed e.g. as a bore 30 having a circular cross-section. The recess 28 has an open edge at the front end 24, i.e. it terminates into the open, wherein a stud 32 is screwed into the opposite side, to which the booster 14 is also connected.

The recess 28 also extends in the direction of the axis 22 and is coaxial thereto. The recess 28 is moreover designed as a stepped bore and has a contraction 34 in the area of the front end 24. A die 36 is moreover disposed in the recess 28 and is displaceable in the direction of the axis 22 to assume its rest position in the location shown in FIG. 1. The area 38 of the recess 28 that adopts the die 36 may thereby have a circular or a polygonal cross-section. Moreover, the die 36 has a tapering end 40 which is dimensioned such that it can penetrate through the contraction 34 and project out of the ultrasound sonotrode 16, as is shown in FIG. 2. The tapering 34 thereby serves as an end stop for the die 36 which then assumes its operating position (FIG. 2).

A pressure chamber 42 is provided on the opposite side of the die 36, which has a connection 44 that terminates in the pressure chamber 42 via a cross hole 46. The connection 44 is located in the oscillation node 48 of the ultrasound sonotrode 16, the latter having an oscillation maximum 50 both at the front end 24 and on the opposite connecting side for the booster 14. This is clearly shown in the diagram of a half wave of λ/2 shown below the cross-section.

A pressure medium, e.g. a fluid, which may be a liquid or a gas, may be introduced via the connection 44 into the pressure chamber 42, thereby moving the die 36 towards the workpiece 12 and partially out of the ultrasound sonotrode 16 (see FIG. 2). The ultrasound sonotrode 16 is subsequently moved together with the booster 14 in the direction of travel S until the end 40 of the die 36 abuts the workpiece 12. There is a constant pressure in the pressure chamber 42, which is detected by a pressure sensor 52 that is also connected to the connection 44. The workpiece 12 is held by the end 40 of the die 36, such that the die 36 serves as a holding-down device.

The ultrasound sonotrode 16 is then moved further towards the workpiece 12 through the distance X until the front end 24 abuts the surface of the workpiece 12 (see FIG. 3). The die 36 is thereby pushed back into the recess 28 against the holding force F_I since the supply force F_S of the sonotrode 16 is larger. The workpiece 12 is held due to the pressure P that prevails in the pressure chamber 42. This pressure P remains constant even when the die 36 is pushed back into the recess 28, since the pressure sensor 52 is connected to a pressure controller 54, which keeps the pressure P constant.

As soon as the front end 24 is supported on the workpiece 12, the workpiece is processed. The area of the workpiece 12 covered by the end 40 of the die 36 is not processed, since the die 36 does not follow the ultrasound oscillations of the ultrasound sonotrode 16. This area is designated on the workpiece 12 with 56.

The die 36 thus serves to fix the workpiece 12 and damp ultrasound oscillations in the area 56 on the workpiece 12. The die 36 may thereby also be designed as a punching tool, such that the workpiece 12 is punched by the die 36 before or after ultrasound processing by increasing the pressure P in the pressure chamber 42. The die 36 is disposed in the recess 28 free of play and can be displaced therein, in particular, in a fluid-tight fashion.

Claims

1. A device for processing a workpiece using ultrasound, the workpiece being disposed between the device and an anvil, the device comprising: an ultrasound sonotrode having a recess, said recess having an axial end opening facing the workpiece and the anvil; and a die disposed in said recess, said die being displaceable between a rest position retracted into said ultrasound sonotrode and an operating position in which said die partially projects out of said ultrasound sonotrode.

2. The device of claim 1, wherein said recess is a bore.

3. The device of claim 2, wherein said bore is a stepped bore.

4. The device of claim 1, further comprising stop means to delimit a displacement path of said die.

5. The device of claim 1, wherein said recess has a circular cross section.

6. The device of claim 1, wherein said recess has a polygonal cross section.

7. The device of claim 1, wherein said die is guided in said recess with or without minimum play.

8. The device of claim 1, wherein said die is disposed in said recess in a fluid-tight or pneumatically tight fashion.

9. The device of claim 1, wherein said recess forms a pressure chamber and has a connection for a fluid.

10. The device of claim 9, wherein said connection is disposed at an oscillation node.

11. The device of claim 9, wherein said connection leads to a fluid and/or pressure sensor.

12. The device of claim 11, further comprising a pressure sensor and a pressure controller communicating with said pressure sensor.

13. The device of claim 1, wherein said ultrasound sonotrode has a supply force which exceeds a force pressing said die out of said recess.

14. The device of claim 1, wherein a surface of said die which contacts the workpiece is structured.

15. The device of claim 1, wherein said die is formed as a punching tool.