Tool for HF welding, installation for producing a bag for medical purposes and method for operating such an installation

Abstract

A system and method for producing a medical bag with an HF welder that uses upper and lower dies each having a plurality of electrode lamellae arranged such that they are alternatingly polarized relative to adjacent lamellae and opposing lamellae. Interspersed dielectric materials may be used to impart contours onto the film material to produce a patterned bag.

Claims

1. A tool for HF welding an inserted part with an axial direction to two films to form a bag, comprising: an upper die; a lower die; wherein each of said upper die and said lower die includes a plurality of electrode lamellae arranged such that said electrode lamellae are alternatingly polarized along said axial direction and oppositely polarized perpendicular to the axial direction.

2. The tool of claim 1 wherein each of the upper die and the lower die have an equal number of electrode lamellae.

3. The tool of claim 1 wherein each of the electrode lamellae of the upper die are separated from adjacent electrode lamellae by solid members of dielectric material.

4. The tool of claim 3 wherein each of the solid members comprises a leading edge that is setback relative to the adjacent electrode lamellae.

5. The tool of claim 3 wherein each of the solid members comprises a leading edge that is flush with the adjacent electrode lamellae.

6. The tool of claim 3 wherein the solid members comprise contoured leading edges.

7. A system for producing a bag for medical purposes, comprising: a film feeder; a filling station; and, a welding station including a tool having: an upper die and a lower die; wherein each of said upper die and said lower die includes a plurality of electrode lamellae arranged such that said electrode lamellae are alternatingly polarized along an axial direction and oppositely polarized perpendicular to the axial direction.

8. The system of claim 7 wherein each of the upper die and the lower die have an equal number of electrode lamellae.

9. The system of claim 7 wherein each of the electrode lamellae of the upper die are separated from adjacent electrode lamellae by solid members of dielectric material.

10. The system of claim 9 wherein each of the solid members comprises a leading edge that is setback relative to the adjacent electrode lamellae.

11. The system of claim 9 wherein each of the solid members comprises a leading edge that is flush with the adjacent electrode lamellae.

12. The system of claim 9 wherein the solid members comprise contoured leading edges.

13. The system of claim 9 further comprising: an HF power circuit: a plurality of support rods usable for holding parts between said upper die and said lower die; wherein said support rods are electrically separated from said HF power circuit.

14. A method of producing a bag for medical purposes comprising: guiding two films and an inserted part with an axial direction into a welding station, the welding station including opposing dies, each of said opposing dies including a plurality of electrode lamellae arranged such that said electrode lamellae are alternatingly polarized relative to adjacent lamellae and oppositely polarized relative to opposing lamellae; positioning the inserted part between the two films; laying the two films against the sides of the inserted part; and, subjecting the electrode lamellae to high-frequency electricity, thereby welding the two films around the inserted part.

15. The method of claim 14 further comprising: providing a plurality of solid dielectric members between adjacent electrode lamellae of each die.

16. The method of claim 15 further comprising producing a flat weld by aligning leading edges of the solid dielectric members and leading edges of the adjacent electrode lamellae such that said leading edges are flush with each other.

17. The method of claim 15 further comprising producing a contoured weld by aligning leading edges of the solid dielectric members and leading edges of the adjacent electrode lamellae such that adjacent leading edges are offset relative to each other.

18. The method of claim 17 wherein said adjacent leading edges are arranged such that said leading edges of said solid dielectric members are setback relative to the leading edges of the adjacent electrode lamellae.

19. The method of claim 15 further comprising producing a contoured weld by providing contoured leading edges of said solid dielectric members.

Description

(1) Below, the invention is explained in more detail with the help of an exemplary embodiment and with reference to the drawing. Shown are

(2) FIG. 1 a schematic section of a welding tool, wherein the direction normal to the section corresponds to an axial direction of an inserted part, with a tubular inserted part in place but not yet welded and two films not yet welded, wherein the direction of the section runs through a pair of electrode lamellae,

(3) FIG. 2 a section through the welding tool, wherein the direction normal to the section corresponds to the axial direction of the inserted part, with a round circular inserted part in place but not yet welded and two films not yet welded,

(4) FIG. 3 a schematic of an exploded 3D view of a welding tool for an inserted part with an axial direction, with an inserted part in place but not yet welded and two films not yet welded, wherein the upper die and the lower die each comprise three electrode lamellae disposed next to one another as an example,

(5) FIG. 4 a schematic of the layout of the HF welding tool in a longitudinal section according to view IV-IV in FIG. 3, with an exemplary embodiment for a dielectric material between the electrode lamellae, the dielectric material having a setback edge relative to the electrode lamellae, wherein the upper die and the lower die each comprise three electrode lamellae disposed next to one another as an example,

(6) FIG. 5 a schematic of the layout of the HF welding tool in a longitudinal section according to view V-V in FIG. 3 with an exemplary embodiment for a dielectric material between the electrode lamellae, the dielectric material ending flush with the electrode lamellae, wherein the upper die and the lower die each comprise three electrode lamellae disposed next to one another as an example, and

(7) FIG. 6 a schematic of the layout of the HF field in the tool in a longitudinal section according to view VI-VI in FIG. 3, wherein the upper die and the lower die both comprise three electrode lamellae disposed next to one another as an example.

(8) The welding tool 1 in FIGS. 1 to 3 consists essentially of an upper die 2 and a lower die 3. The tool is designed to carry out an HF surface welding process, in particular a pure HF surface welding process.

(9) The HF surface welding process which uses welding tool 1 is intended to provide a fused seal of parts with an axial direction inserted between the upper film 4 and the lower film 5.

(10) The upper die 2 and the lower die 3 are two electrically separated electrodes and can be polarized differently by the welding tool 1. The electrodes simultaneously enable a fused seal of both the upper film 4 to lower film 5 and between the films and the inserted part in a single welding procedure.

(11) During the welding procedure, the upper die 2 and the lower die 3 are polarized differently. In this way, a symmetric HF primary field is set up between the electrodes.

(12) For example, this enables the tubular inserted part 6 in FIG. 1 to be sealed by fusion to the films. However, it is not necessary for the inserted piece with the axial direction to be a hollow member. It can also be a circular solid member such as the circular inserted piece 7 (see FIG. 2).

(13) Of course, other cross sections of inserted pieces can be advantageous, for example those in the shape of an oval, a polygon, a rectangle, a diamond with sharp or round corners, or a square.

(14) These cross sections can be provided with an internal opening. In the process, it is not necessarily required for this opening to have a round cross section or to be centrally positioned. There are also other conceivable cross sections of the opening of inserted pieces, for example in the form of an oval, a polygon, a rectangle, or a square.

(15) It is expressly noted that an alternative, advantageous design not shown here can be to distribute along the periphery of the medical bag a plurality of inserted parts with an axial direction. In this way, medical bags with a plurality of inserted parts can be produced, said parts having a plurality of tubular openings, for example.

(16) Since tool 1 is designed symmetric with respect to upper die 2 and lower die 3 relative to the plane of separation between upper film 4 and lower film 5, a symmetrical layout sets up during the welding procedure both with respect to the main HF field and with respect to the HF stray field which will be introduced and further explained below. The welding therefore proceeds very homogeneously.

(17) The welding tool 1 comprises a plurality of upper die electrode lamellae disposed in parallel next to one another in an upper die assembly 20 and a plurality of lower die electrode lamellae disposed in parallel next to one another in a lower die assembly 30.

(18) The upper die assembly 20 comprises a first upper electrode lamella 21, a parallel second upper electrode lamella 22 and a parallel third upper electrode lamella 23. The lower die assembly 30 is designed symmetrical with respect to the upper die assembly 20. Thus, a first lower electrode lamella 31, a parallel second lower electrode lamella 32 and a parallel third lower electrode lamella 33 are located at the same axial height.

(19) Of course, a pair of just two parallel upper and symmetrical lower electrode lamellae can be implemented as well. Furthermore, any multiple of parallel upper and symmetric lower electrode lamellae are possible.

(20) The electrode lamellae have a central area with recesses in order to hold the inserted piece with an axial direction. The shape of the recesses depends on the geometry of the inserted piece to be sealed in.

(21) The recesses at the electrode lamellae allow the lamellae to be pressed flat against the surface of the inserted piece during operation under pressure, wherein the upper film 4 and the lower film 5 are pressed inward while surrounding the inserted part in the area of the recess.

(22) During the welding process, a polarization of the electrode lamellae is selected such that the electrode lamellae are alternatingly polarized along the axial direction and oppositely polarized perpendicular thereto (see FIG. 6).

(23) In the process, axially parallel main HF fields 51 set up between the electrode lamellae of the upper die 2 which are oriented parallel with one another, and between the electrode lamellae of the lower die 3 which are oriented parallel with one another.

(24) Furthermore, as a result of the arrangement of the electrode lamellae and the polarization of the electrode lamellae, axially normal main HF fields 52 result between the symmetrically-disposed electrode lamellae of the upper die 2 and the lower die 3, respectively.

(25) Also, HF stray fields 53 issue from the edges of the electrode lamellae, the fields being characterized in that the field lines cannot be described by a straight line.

(26) The HF stray fields also result between adjacent electrode lamellae of different respective polarities.

(27) Since for cross-field welding the tool 1 disclosed here has a different polarity for all adjacent electrode lamellae, both in when upper die 2 and lower die 3 are viewed separately and when HF tool 1 is viewed as a whole, this gives rise to the characteristic cross field model of HF stray field 53

(28) Tool 1 facilitates the welding both of the films with one another and of the films to the surface of the inserted parts in a single welding procedure.

(29) The main HF fields are primarily responsible for the welding of the films to one another and the HF stray fields 53 are primarily responsible for the welding of the films to the surface of the inserted part.

(30) In an alternative embodiment of the HF welding tool 1 (see FIGS. 4 and 5), the electrode lamellae of upper die 2 and lower die 3 are separated from one another along the axial direction of the inserted part by way of a dielectric material 40 which comprises a solid member.

(31) As was already explained above, almost any geometry of inserted parts can also be sealed between the electrode lamellae in the alternative embodiment of HF welding tool 1 described here. In the process, the contour of the recess of the electrode lamellae may have to be adapted.

(32) The geometry of the dielectric material 40 can be varied. In the process, it is possible that the dielectric material 40 has a setback edge and/or forward edge 41 relative to the electrode lamellae or ends flush with the electrode lamellae (see flush edge 42).

(33) Thus, it is possible to structure the contour in the welding area at the bag being produced such that a desired contour results; this is because the plastic begins to flow during the welding procedure and so can flow into the contouring of the dielectric material 40 due to the shape thereof.

(34) Furthermore, this contour can also be adapted to positively lock with components positioned thereon.

(35) Also, the contouring of the dielectric material 40 enables a targeted distribution of the energy input into the individual areas welded so that as perfect and homogeneous of a weld can be achieved as possible.

(36) Also, by being able to control energy input this way, an especially energy efficient, homogeneous HF weld can be achieved in only a single welding process.

LIST OF REFERENCE SIGNS USED

(37) 1 Welding tool 2 Upper tool 3 Lower tool 4 Upper film 5 Lower film 6 Tubular inserted part 7 Round inserted part 20 Upper tool assembly 21 First upper electrode lamella 22 Second upper electrode lamella 23 Third upper electrode lamella 30 Lower tool assembly 31 First lower electrode lamella 32 Second lower electrode lamella 33 Third lower electrode lamella 40 Dielectric material 41 Leading edge 42 Flush edge 51 Axially-parallel main HF field 52 Axially-normal main HF field 53 HF stray field