Sonotrode, device and method for producing a join

Abstract

A sonotrode (18) for producing a welded and/or soldered join between a cable (17) and a sheath (17), covering the cable (17), comprising at least one working surface (2). The working surface (2) is curved in a concave manner, at least in sections. An anvil (10) comprises at least one counter surface (11) which is curved in a concave manner, at least in sections. The device for producing the join between a cable (17) and a sheath (17), covering the cable (17), comprises a sonotrode (18) joined to an ultrasound source (8) at least at a joining surface (5), and comprising an anvil (10) arranged opposite the working surface (2) of the sonotrode (18). A method for producing a join between a cable (17) and a sheath (17) covering the cable (17) is also disclosed.

Claims

1. A torsion sonotrode having a torsion axis for producing a joint between a cable and a sheath covering the cable, the sonotrode having at least one working face, wherein the working face is concavely curved in a cross-sectional plane perpendicular to the torsion axis forming a single groove along a length of the working face; a symmetrical mass distribution with regard to a first plane of symmetry; and at least one connecting face for connecting to an ultrasonic source for applying a torsional vibration, such that the working face is moved back and forth in a direction perpendicular to the torsion axis of the sonotrode to produce the joint between the cable and the sheath; the torsion axis extending through the connecting face and the first plane of symmetry; the single groove being configured to align the sheath such that an axis of the sheath is approximately aligned with the groove in the working face when the working face is pressed against the sheath.

2. The sonotrode as claimed in claim 1, wherein the working face is convexly curved at least sectionally in a second profile extending parallel to the torsion axis.

3. The sonotrode as claimed claim 1, wherein the first profile has a groove which is configured such that when a pressure or a force is exerted on the sheath by the working face, the sheath is forced into a defined position with respect to the working face.

4. The sonotrode as claimed in claim 3, wherein the working face has, in each case, a protruding and pressure face on either side of the groove.

5. The sonotrode as claimed in claim 1, wherein a surface of the working face has a mean roughness (Ra) of at most 0.4 m.

6. An apparatus for producing a joint between a cable and a sheath covering the cable, the apparatus comprising: a sonotrode connected to an ultrasonic source at least at a connecting face, and an anvil arranged opposite the working face of the sonotrode, wherein the sonotrode is configured as claimed in claim 1.

7. The apparatus as claimed in claim 6, wherein a counterpart face of the anvil, arranged opposite the working face, has a mean roughness (Ra) of at most 0.4 m.

8. The apparatus as claimed in claim 6, wherein the anvil has two parallel shoulders, in a surface portion adjoining the counterpart face, for retaining a connection terminal so as to prevent the connection terminal from shifting to the side.

9. A method for producing a joint between a cable and a sheath covering the cable, the method comprising: providing an apparatus having a sonotrode as claimed in claim 1, positioning the sheath such that an axis of the sheath is approximately aligned with a groove axis of the groove in the working face, applying the sheath, either before or after the positioning of the sheath, to the cable, pressing the working face against the sheath such that the axis of the sheath is aligned with the groove axis, and imparting an ultrasonic vibration into the sheath by the sonotrode such that the cable is at least sectionally connected to the sheath using a torsional vibration such that the working face is moved back and forth in a direction perpendicular to the torsion axis of the sonotrode to produce the joint between the cable and the sheath.

10. The method as claimed in claim 9, wherein, in the sonotrode, a spacing between pressure faces of the working face is smaller than an outside diameter of the sheath.

11. The method as claimed in claim 9, wherein, in the sonotrode, a spacing between the pressure faces of the working face is greater than an outside diameter of the sheath.

12. The method as claimed in claim 9, wherein positioning of the sheath takes place by placing the sheath on an anvil arranged opposite the working face.

13. The method as claimed in claim 9, wherein the sheath is a constituent part of a tubular cable lug having a connection terminal.

14. The method as claimed in claim 13, wherein the connection terminal is laid between shoulders of the anvil.

15. The method as claimed in claim 9, wherein the cable is at least one of welded and soldered to the sheath at least sectionally and the joint is at least one of a welded joint and a soldered joint.

16. The method as claimed in claim 15, wherein the sheath is a sleeve.

17. The method as claimed in claim 16, wherein the sleeve is a metal sleeve.

Description

(1) Exemplary embodiments of the invention are explained in more detail in the following text with reference to the drawings, in which:

(2) FIG. 1 shows a first side view of a first sonotrode,

(3) FIG. 2 shows a front view of the first sonotrode,

(4) FIG. 3 shows a rear view of the first sonotrode,

(5) FIG. 4 shows a plan view of the first sonotrode,

(6) FIG. 5 shows a side view of a second sonotrode,

(7) FIG. 6 shows a front or rear view of the second sonotrode,

(8) FIG. 7 shows a plan view of the second sonotrode,

(9) FIG. 8 schematically shows a first ultrasonic welding device,

(10) FIG. 9 schematically shows a second ultrasonic welding device,

(11) FIG. 10 shows the orientation of the metal sleeve as the working face approaches,

(12) FIG. 11 shows the orientation of the metal sleeve as the working face makes contact,

(13) FIG. 12 shows the orientation of the metal sleeve as the working face is pressed in,

(14) FIG. 13 shows a plan view of an anvil with a tubular cable lug,

(15) FIG. 14 shows a side view according to FIG. 13,

(16) FIG. 15 shows a front view of a third sonotrode,

(17) FIG. 16 shows a detail view of the second sonotrode according to FIG. 5, and

(18) FIG. 17 shows a view in partial section through a fourth sonotrode,

(19) FIG. 18a-d show sectional views of four pairs of sonotrodes and anvils for producing different profiles;

(20) FIG. 19 shows an ultrasonic welding device with two side slides;

(21) FIG. 20a/b show an ultrasonic welding device in which the spacing between pressure faces of the working face is greater than the outside diameter of the sheath, before and after centering.

(22) FIGS. 1 to 4 show views of a first sonotrode according to the invention. The first sonotrode has a first plane of symmetry S1. The masses are distributed symmetrically with regard to the first plane of symmetry S1. An axis X of the first sonotrode lies in the first plane of symmetry S1. The axis X corresponds to an axis of rotation of a cylindrical portion of the first sonotrode. Working faces 2 extend in a manner arranged opposite one another from a cylindrical shaft 1 of the sonotrode.

(23) FIG. 1 shows a first profile of the working faces 2. The first profile extends parallel to the axis X. The working faces 2 have a convex curvature in the first profile. They are configured in the manner of a full bead here.

(24) As is apparent in particular from FIGS. 2 to 4, the working faces 2 extend perpendicularly to the axis X. In a second profile, likewise extending perpendicularly to the axis X, each of the working faces 2 has a concave portion, or a groove 3, which is delimited on either side by protruding humplike pressure faces 4. Each pressure face 4 has a central point M in plan view (see FIG. 4). A groove axis R connects the lowest points of the groove 3. The first sonotrode has a first connecting face 5 with a threaded bore 6. Furthermore, the first sonotrode is provided with an encircling contact face 7 which, between the first connecting face 5 and the working faces 2, extends radially from the shaft 1.

(25) The second sonotrode according to the invention, shown in FIGS. 5 to 7, differs from the first sonotrode substantially in that both the front side of the sonotrode and the rear side thereof each have a connecting face 5 in this case. Respective contact faces 7 are provided between each connecting face 5 and the working face 2. The working face 2 is in this case fitted on the cylindrical shaft 1 centrally between the two connecting faces 5.

(26) A surface of the pressure faces 4 has a mean roughness R.sub.a of at most 0.1 m. The groove 3, too, can have a mean roughness R.sub.a of at most 0.1 m. Preferably, the working face 2 is polished.

(27) FIG. 8 schematically shows a first ultrasonic welding apparatus according to the invention. An ultrasonic source 8 is in this case connected to the first sonotrode, shown in FIGS. 1 to 4, at the connecting face 5 thereof. The reference sign 9 schematically denotes a pressure generating device which acts on the contact face 7 of the first sonotrode. The reference sign 10 denotes an anvil which has a counterpart face 11 located opposite the working face 2.

(28) FIG. 9 shows a schematic view of a second ultrasonic welding apparatus according to the invention. In this case, the second sonotrode, shown in FIGS. 5 to 7, is connected to an ultrasonic source 8, in each case at the connecting faces 5 thereof. The pressure generating device 9 is in this case supported on two contact faces 7.

(29) The function of the ultrasonic welding apparatuses will now be explained in more detail in particular in conjunction with FIGS. 10 to 14.

(30) By means of the pressure generating device 9, the working face 2 of the sonotrode is moved in the direction of the counterpart face 11 of the anvil 10. Located on the smoothly configured counterpart face 11 of the anvil 10 is a metal sleeve 12, which is for example a constituent of a tubular cable lug 13. The metal sleeve 12 has a second plane of symmetry S2. The second plane of symmetry S2 is, as the working face 2 approaches, first of all not aligned with a third plane of symmetry S3, which extends perpendicularly to the first plane of symmetry S1 through the axis X of the sonotrode. The groove axis R is preferably located in the third plane of symmetry S3.

(31) A spacing between the two central points M of the pressure faces 4 is designated by the reference sign A. The reference sign D designates an outside diameter of the metal sleeve 12. The spacing A is smaller than the outside diameter D of the metal sleeve 12 in this exemplary embodiment. The following relationship preferably applies:
A=k*D, where

(32) k is a factor in the range from 0.5 to 0.9, preferably 0.6 to 0.8.

(33) As soon as one of the pressure faces 4 comes into contact with the outer circumference of the metal sleeve 12, upon further movement of the pressure face 4 in the direction of the counterpart face 11, the metal sleeve 12 is shifted such that the second plane of symmetry S2 thereof is aligned with the third plane of symmetry S3 of the sonotrode (see FIGS. 11 and 12). By way of the pressure generating device 9, the working face 2 is then pressed into the metal sleeve 12 and an ultrasonic vibration is imparted by means of the sonotrode.

(34) FIGS. 13 and 14 show a configuration of an anvil 10 on which a tubular cable lug 13 has been placed. The tubular cable lug 13 has a metal sleeve 12, which rests on the smooth counterpart face 11. In a surface portion 15 adjacent to the counterpart face 11, the anvil 10 has two parallel shoulders 16. From the metal sleeve 12 there extends a connection terminal 14. As a result of the connection terminal 14 being placed between the parallel arranged shoulders 16, a rough orientation of the metal sleeve 12 with regard to the working face 2 is defined. A spacing between the shoulders 16 is expediently selected such that the connection terminal 14 can be shifted to the side in a defined range. A cable 17 has been plugged into the metal sleeve 12. The metal sleeve 12 forms a sheath of the cable 17 in this. The tubular cable lug 13 can be nickel-plated.

(35) With the sonotrode according to the invention, a reproducible and firm welded joint and/or soldered joint between a metal sleeve 12 and a cable 17 plugged into the latter is produced in particular when the torsional ultrasonic welding method is used. The cable 17 can be in particular a litz wire, for example made of copper or aluminum. With the proposed ultrasonic welding apparatus, a cable 17 can be welded and/or soldered to a tubular cable lug 13 without the surface of the connection terminal 14 being damaged, in particular scratched. The lack of surface structures on the working face 2 and on the counterpart face 11 additionally has the effect that the friction between the sonotrode, metal sleeve 12 and anvil 10 is increased and as a result the development of heat is enhanced. It is currently assumed that, as a result, a cohesive connection is achieved in the interior of the metal sleeve 12 in cooperation with the welding force applied. Furthermore, the lack of a surface structure has the advantage that the wear to the working face 2 and the counterpart face 11 is reduced. As a result, longer and greater energy input is possible. Such wear is particularly pronounced in particular in nickel-plated tubular cable lugs 13, and this can be prevented by the invention.

(36) In the third sonotrode shown in FIG. 15, the working face 2 has a concave curvature along its entire length L in the second profile shown here. A shortest distance between the mutually opposite lines of curvature of the two working faces 2 advantageously intersects the axis X.

(37) FIG. 16 shows a detail view according to FIG. 5. It is apparent therefrom that, in the first profile shown here, the working face 2 is curved through an angle of 180.

(38) In the fourth sonotrode shown in FIG. 17, the working face 2 is, by contrast, curved only through an angle of about 100 in the first profile.

(39) FIGS. 18a to 18d illustrate four pairs of sonotrodes 18 and anvils 10 in sectional views, in which the second profile is visible. The metal sleeves 12 and cables 17 can likewise be seen after being connected. In FIGS. 18a, 18c and 18d, the second profiles of sonotrodes 18 and anvil 10 each have both convex and concave portions. In FIG. 18b, only the second profile of the anvil 10 has a convex profile, but not also the second profile of the sonotrode 18.

(40) FIG. 19 shows a further welding device according to the invention, which, apart from a sonotrode 18 and an anvil 10, contains two side slides 19, arranged opposite one another, each with a side boundary surface 20. The sonotrode 18 is shiftable in the direction of the anvil 10 in a closing direction B that is vertical in this case. The side slides 19 are shiftable in a transverse direction Q perpendicular to the closing direction B. The working face 2 of the sonotrode 18, the counterpart face 11 of the anvil 10, and the side boundary surfaces 20 of the side slides 10 enclose a spatial region in which the connection takes place. The side slides 19 define a rough orientation of the metal sleeve 12 with regard to the working face 2.

(41) In the ultrasonic welding apparatus illustrated in FIGS. 20a and 20b, the spacing between pressure faces 4 of the working face 12 of the sonotrode 18 is greater than the outside diameter of the metal sleeve 12. In this way, with one and the same sonotrode 18, it is also possible to connect metal sleeves 12 with different outside diameters to respective cables. Furthermore, the self-centering upon adjustment of the sonotrode 18 in the direction of the anvil 10 is improved, and a more uniform force input takes place. FIG. 20a shows the state before centering and FIG. 20b shows the state after centering.