GB2101521A

GB2101521A - Moulding a case for a hearing aid

Info

Publication number: GB2101521A
Application number: GB08220262A
Authority: GB
Inventors: Adolf Langner
Original assignee: Viennatone GmbH
Current assignee: Viennatone GmbH
Priority date: 1981-07-15
Filing date: 1982-07-13
Publication date: 1983-01-19
Also published as: DE3224654A1; AT371661B; GB2101521B; ATA312481A

Abstract

A method and apparatus for moulding a hearing aid case are described. The apparatus consists of a mould core 1, 2, 2a on an adjustable supporting frame. A female mould 15 is formed from an impression of the ear cavity and is positioned on the base 10. The core 1, 2, 2a is lowered to the floor of the mould and the frame adjusted to hold the core in the correct position. The core is then withdrawn by raising the beam 3 and spacers 13, 14 placed between ring 11 and beam 6 ensure that a gap is left when the core is replaced in the mould. The mould is filled with moulding material and the core lowered into it. When set the mould and core are removed from the apparatus and the moulding material is hardened. Removal of the mould and core leaves a thin walled case for a hearing aid. <IMAGE>

Description

SPECIFICATION Method and device for producing an ear cavity body The invention refers to a method for producing an ear cavity body to receive an in-ear hearing aid, whereby a hardening moulding material is poured into a negative mould produced in a known manner, and in order to form the space to receive the hearing aid, a mould core in the dimensions of the hearing aid is pressed into the moulding material, and after this has hardened the moulding core is removed from the ear cavity body.

The practical value of a hearing aid is assured, apart from the quality of the hearing aid itself, almost exclusively by the best possible contact of the aid with the patient's ear by means of an individually fitted ear cavity body. This particularly applies to in-ear aids. Apart from this, in an aid of this type, which is worn completely inside the external ear, its position inside the external ear, or ear cavity, an important criterium. Thus for the best possible cosmetic effect, the heating aid should project as little as possible from the external ear, which requires the deepest possible positioning of the aid in the ear cavity. Thus, it is necessary that the aid should be placed as deeply as possible in the ear cavity, but it should be placed so that the aid does not press on points in or on the external ear.

Principally two procedures have been known up to now for providing this free positioning for the in-ear hearing aid: 1)An ear cavity body produced in a usual way is milled out to provide a space to receive the hearing aid.

2) In moulding the ear cavity body in the usual way in a plaster cast, a loose dummy corresponding to the in-ear aid is moulded into the mould.

The first method is very time-consuming on account of the geometrically irregular shape of an in-ear hearing aid, and generally results in a solution which is neither mechanically nor acoustically very satisfying.

The second method, in which a dummy is simply pressed into the not-yet-hardened ear cavity material, often leads to an undefined position in the depth of the negative mould, as well as to a generally not ideal position of the sound outlet fittings of the aid with relation to the ear-tube. Furthermore, the dummy used, which is usually made of cheap plastic, is often not able to be reused for another ear cavity body after the moulding material has hardened.

The invention is intended to do away with the disadvantages of the known methods. This is achieved - based on a method of the type referred to above - in that, before the moulding material is poured into the mould the moulding core is hung by means of a supporting element into the negative mould, adjusted and fixed in a predetermined position in the empty negative mould, whereby preferably the part of the moulding core destined for the second outlet fittings is adjusted and fixed, then the moulding core is removed from the negative mould but preserving the adjusted and fixed values, and after the moulding material is poured into the mould, the moulding core is replaced in the moulding material in the predetermined position.

The procedure according to the invention allows the optimum arrangement of an in-ear hearing aid within the negative mould of the ear cavity, whereby the position can be exactly and reproducibly established before the mould material is poured in. The dummy, i.e. the moulding core corresponding with the hearing aid has in it a movable dummy for the sound outlet fittings, and with the aid of this the exact position of the sound outlet fittings relative to the ear-tube can be adjusted before the moulding material is poured in.

In order to achieve an exactly defined wall thickness at the base of the ear cavity body, it is provided for, according to a further embodiment of the method according to the invention, that the moulding core is first of all sunk to the base of the negative mould and then raised to an extent corresponding with the desired wall thickness of the ear cavity body.

The invention also concerns a device for carrying out the method according to the invention, characterized by a sliding element functioning as a supporting element, adjustable in height in a vertical direction and held by a beam, the moulding core being fixable to the underside of the sliding element, and which by means of an adjusting arrangement fixes the moulding core in the predetermined position.

In order to achieve in a simple manner an exact adjustment and fixing of the predetermined position of the moulding core, it is provided for that the beam holding the sliding element is rotatable around a horizontal axis, and the beam is fixable in differing rotation positions by means of an adjusting screw, whereby preferably a stopping ring, adjustable in height, is fixed to the sliding element above the beam. A particularly good adjustability of the moulding core in the predetermined position can be achieved in that the beam is borne by a stand, which can be fixed by means of an adjusting screw in differing positions, on a ball joint on its under side, whereby preferably the moulding core is rotatable around a vertical axis by means of a pin on the under side of the sliding element, and fixable by means of an adjusting screw.

In order to easily achieve the desired wall thickness at the base of the ear cavity body, the invention provides that, between the upper surface of the beam and the under side of the stopping ring, spacing plates are rotatably arranged.

A distinct and secure fixing of the position between the device according to the invention and the negative mould can most suitably be achieved by fixing the mould on a base plate having openings to take up pins provided for on the under side of the negative mould and serving to distinctly fix its position.

The invention is described in the following with reference to the drawings.

Fig. 1 shows an elevation of a device for carrying out the method according to the invention.

Fig. 2 shows a top view of the device according to fig. 1.

A moulding core corresponding in shape to the in-ear hearing aid, comprising a further movable part for the sound outlet fittings 2, the angle and position of which exactly correspond with the hearing aid, is fixably attached by means of screw 5 and rotatably attached to a sliding element 3 by means of the pin 4. The sliding element 3 with the moulding core 1, 2 is on a beam 6, this being attached rotatably and swivelling in all directions to a base plate 10 by means of an adjusting screw 7, a stand 8 and a ball joint 9. The sliding element 3 3 is vertically slidable in the beam 6, whereby the vertical path can be fixed by the adjusting ring 1 1 with a screw 12.Spacing plates 13, 14 of different thicknesses can be swivelled between the beam 6 and the adjusting ring 11, and with their help the minimum wall thickness of the ear cavity can later be established.

A negative plaster mould 15 is set upon the base plate 10 beneath the moulding core 1, whereby centring is provided by studs 16 of varying diameters in the casting, which engage in corresponding holes 17 in the base plate 10.

The ear cavity is produced as follows: a negative mould in plaster is produced from a patient's ear impression made in the usual way, in a a plastic or rubber mould cup with depressions in its base for forming the centring studs 17.

This plaster mould is removed after hardening from the mould cup and set on the base plate 10, whereby the two studs 16 assure the defined position. All fixing means (joint screw 7, ball joint 9, adjusting ring 11, 12, etc)., are loosened and the sound-outlet dummy 2 is pulled back so that the actual sound outlet 2a is flush with the aid dummy 1.

Now the moulding core on the vertically movable sliding element 3 is pushed from above into the plaster negative mould, and the part for the sound outlet 2 is again pushed into the moulding core until it is stopped.

The whole moulding core 1,2, the dimensions of which now correspond exactly with those of the in-ear hearing aid, can be rotated on a vertical axis by means of the pin 4 and swivelled by means of the rod and joints 6, 7, 8, 9 in all directions until the moulding core 1, 2 has an optimum position in the plaster negative mould. The moulding core is hereby placed on the base of the plaster negative mould.

In the established position, the beam 6 and the stand 8 are fixed by means of the fixing screws 7, 18. In the same way, the adjusted ring 1 1 is pushed until it stops onto the beam 6 and fixed with the screw 12, and the screw 5 is turned as far as possible. After a further check of the position of the moulding core 1, 2 in the plaster mould, part 2 is pulled back and the sliding element 3 is raised, whereby nothing else is changed in the defined position of all parts with relation to each other.

After pouring the moulding material into the plaster mould 1 5. one or more of the spacing plates 13, 14 are swivelled between the beam 6 and the adjusting ring 11, and the sliding element 3 with the moulding core is once more pushed downwards until it stops. By swivelling in the spacing plates 13, 14, the moulding core is no longer positioned on the base of the negative plaster mould, but allows the formation of a small wall thickness of the moulding material below the moulding core 1, 2. Part 2 for the sound-outlet fittings is also pushed in as far as possible, whereby its front part 2a later forms the actual hole for the fittings of the aid in the ear cavity.

After the moulding material has set the moulding core 1, 2 is removed from the device by loosening the adjusting screw 5, the sliding element 3 is raised and the plaster mould 15, after removing from the device, is subjected to the usual treatment (pressure vessel, stove) for further hardening of the moulding material.

After the ear cavity material has completely hardened, first of all part 2 of the moulding core 1 is withdrawn, and then the moulding core is removed from the finished ear cavity. The free space thus formed in the ear cavity corresponds with the shape of the in-ear hearing aid and the predetermined position of the aid within the ear cavity, i.e. the position of the sound outlet fittings with relation to the ear tube. The space thus produced can be used for placing the corresponding in-ear aid without further treatment. The ear cavity body itself is finished in the known manner by drilling a sound channel and polishing the surface.

According to the known moulding materials used for the ear cavity body, the moulding core 1, 2 can be made of heat-resisting plastic material, steel, or suchlike, in any case out of a material which does not combine with the ear cavity body material. The somewhat higher costs of the moulding core 1, 2 are practically irrelevant, as the dummy can be used repeatedly for a particular inear hearing aid.

Claims

1. Method for producing an ear cavity body for receiving an in-ear hearing aid, whereby a hardening moulding material is poured into a negative mould produced in a known manner, and in order to form the space to receive the hearing aid, a moulding core in the dimensions of the hearing aid is pressed into the moulding material, and after this has hardened the moulding core is removed from the ear cavity body, characterized in that, before the moulding material is poured in, the moulding core is set hanging from a supporting element in the negative mould and adjusted in the empty negative mould in a predetermined position and fixed in this position, then the moulding core is removed from the predetermined position, but preserving the adjusted and fixed values and, after pouring in the moulding material, the moulding core is replaced in the moulding material in the predetermined position.

2. Method according to claim 1, characterized in that the moulding core is first of all sunk to the floor of the negative mould and then raised to the extent that corresponds with the desired wall thickness of the ear cavity body.

3. Device for carrying out the method according to claims 1 or 2, characterized by a sliding element functioning as a support element, adjustable in height in a vertical direction and held by a beam (6), the moulding core (1, 2) being attachable to the under side of the sliding element, and which by means of an adjusting arrangement (11, 12) fixes the moulding core in the predetermined position.

4. Device according to claim 3, characterized in that the beam (6) holding the sliding element (3) is rotatable around a horizontal axis (19), and the beam (6) is fixed in varying rotation positions by means of an adjusting screw (7).

5. Device according to one of the claims 3 and 4, characterized in that a stopping ring (11) is fixed to the sliding element (3) above the beam (6).

6. Device according to claims 3 to 5, characterized in that the beam (6) is borne by a stand (8), which is adjustably held by means of an adjusting screw (18) in various positions on a ball joint on its under side.

7. Device according to one of the claims 3 to 6, characterized in that the moulding core (1, 2) is, by means of a pin (4) on the under side of the sliding element (3) rotatable around a vertical axis (20) and can be fixed by means of an adjusting screw (5).

8. Device according to one of the claims 3 to 7, characterized in that between the upper surface of the beam (6) and the under surface of the stopping ring (11), spacing plates (13, 14) are rotatably arranged.

9. Device according to one of the claims 3 to 6, characterized in that it is fixed to a base plate which, in order to distinctly fix the position of the negative mould (15) has openings to receive pins provided for on the under side of the negative mould.

10. A method according to claim 1 conducted substantially as described herein with reference to the drawings.

11. A device according to claim 1, substantially as described herein with reference to and as shown in the drawings.