WO2014124723A1

WO2014124723A1 - Method for producing a rotary bearing

Info

Publication number: WO2014124723A1
Application number: PCT/EP2014/000110
Authority: WO
Inventors: Martin Wieters
Original assignee: Olympus Winter & Ibe Gmbh
Priority date: 2013-02-12
Filing date: 2014-01-16
Publication date: 2014-08-21

Abstract

The invention relates to a method for producing a rotary bearing (7, 8) for the image sensor (5) and/or the objective (4) of a video endoscope (1), said rotary bearing consisting of two parts (9, 6; 12, 13), running surfaces of which run one over the other in a tight fitting manner. The invention is characterized in that a first of the two parts (12, 9) is first provided with the respective running surfaces; the running surfaces are then coated with a sacrificial layer (14); the second of the two parts (13, 6) together with the respective running surfaces is then formed on the sacrificial layer; and finally the sacrificial layer (14) is removed.

Description

Method for producing a rotary bearing

The invention relates to a method referred to in the preamble of claim 1 Art.

A rotary bearing of this type is described in DE 10 2004 044 1 19 AI. DE 201 13 031 U1 shows a further video endoscope of this type. In such video endoscopes, the image sensor and / or the objective are rotatably arranged. It depends on a high-precision storage. In the known construction, the pivot bearing is made of turned parts, which are made in machining production.

This results in high manufacturing costs and the need to use very precise and therefore expensive production techniques to avoid fit inaccuracies.

The object of the present invention is to provide a method with which generic pivot bearings can be manufactured inexpensively and precisely.

CONFIRMATION COPY This object is achieved with the features of the characterizing part of claim 1.

According to the invention, at first a first of the two parts of the bearing which run on one another with running surfaces is produced and provided with a sacrificial layer on the running surfaces. Then, the second part is molded with its treads on the sacrificial layer. Both parts are now fitting exactly at the distance of the sacrificial layer together. Subsequently, the sacrificial layer is removed, so as to obtain the two parts, which are separated by a narrow gap, in which was previously the sacrificial layer.

In the manufacturing method according to the invention only a first of the matching parts with its treads must be made highly accurate. The second part adapts itself during production. As a result, the production is much easier. The application and removal of the sacrificial layer is not a technical problem.

The removal of the sacrificial layer can be done in different ways. Preferably, according to claim 2, the sacrificial layer is removed by etching and / or dissolving. There are many materials for the sacrificial layer and also for the parts of the pivot bearing, which enable etching away or dissolving the sacrificial layer without damaging the pivot bearing parts.

The molding of the second part can be done in different ways, wherein advantageously according to claim 3, the injection molding technique is used, which is particularly suitable for plastic materials.

Alternatively it can be sintered advantageous according to claim 3, which is well suited for parts made of metal or ceramic. The sacrificial layer could then consist, for example, of a more easily fusible material. The invention is shown by way of example and schematically in the drawing. Show it:

1 shows a longitudinal section through the distal end portion of a video endoscope according to the invention with a distal and a proximal bearing,

FIG. 2 is an enlarged sectional view of the proximal bearing during manufacture;

FIG. 3 shows a representation corresponding to FIG. 2 of the same proximal bearing, but after completion of the production process,

Figure 4 is an enlarged sectional view of the distal bearing during the

Production and

Figure 5 is a representation corresponding to Figure 2 of the same distal bearing, but after completion of the manufacturing process.

FIG. 1 shows, in longitudinal section, the distal end region of the shaft of a video endoscope 1, which essentially corresponds to the construction shown in DE 10 2004 044 119 A1, to the explanations of which reference is therefore made.

The illustrated shaft of the video endoscope 1 is formed by an enclosing tube 2 in which an obliquely-looking, distal objective part 3 is arranged at the distal end. A proximal objective part 4 is fastened together with an image sensor 5 in a rotary tube 6, which is rotatably mounted with respect to the stationary outer tube 2 with a distal bearing 7 and with a proximal bearing 8. Considering the two-part formed lens 3, 4 and the arrangement of the image sensor 5, it is clear that the adjustment of the lens parts 3 and 4 to each other is extremely critical. The distal objective part 3 is fixed in the fixed outer tube 2. The rotary tube 6 must therefore be stored very accurately relative to the tube 2. It is required a highly accurate storage in both the radial and in the axial direction.

In the construction shown in Figure 1, both bearings 7 and 8 serve for radial guidance. The distal bearing 7 serves in addition to the axial guidance.

For this purpose, the distal bearing 7 is provided with a fixed outer bearing ring 9, which is fixed on the inner surface of the outer stationary tube 2 and runs in a groove 10 in a thickened part of the rotary tube 6.

The proximal bearing 8 consists in a simpler construction of a mounted on the inner surface of the fixed tube 2 outer ring 12 and an attached to the rotary tube 6 inner ring 13, which run with their bearing surfaces to each other.

In order to ensure the required precision of the optical alignment of the lens parts 3 and 4 and also the precise focusing of the image sensor 5, the fits between the bearing ring 9 and the groove 10 and between the rings 12 and 13 must be very narrow. This means that the gaps between them have to be very small. On the other hand, of course, clamping danger must be avoided. It is difficult to produce parts with such tight tolerances.

Here, the invention provides a remedy. This will now be explained with reference to the production of the two bearings 8 and 9. For this purpose, the proximal bearing 8 is first shown greatly enlarged in Figures 2 and 3. In the production method according to the invention, the outer ring 12 is first produced, for example by means of conventional machining methods or casting methods. Then, a sacrificial layer 14 is applied, which, like the embodiment of FIG. 2, is applied over the entire inner surface of the outer ring 12 for the sake of simplicity.

The application of the sacrificial layer 14 can be accomplished by many suitable methods, such as e.g. Painting, dipping, spraying, vapor deposition, sputtering or the like.

Subsequently, the inner ring 13 is formed on the sacrificial layer 14 at the required location, which is shown in Figure 2. For example, it can be pressed against it or made on it, for example, by injection molding or sintering in suitable casting molds.

The sacrificial layer 14 can be applied extremely thin and precise. After forming the inner ring 13 on this, the inner ring 13 has an outer surface which is very precise at a distance from the thickness of the sacrificial layer 14 parallel to the inner surface of the outer ring 12.

In a last manufacturing step, the sacrificial layer 14 is removed. It then results in the finished bearing 8, as Figure 3 shows. The drawn gap 15 corresponds to the now missing sacrificial layer 14. In FIG. 3, the gap 15 is increased disproportionately. In a real embodiment, for example, it could amount to a few μ.

The production of the distal bearing 9 is explained with reference to FIGS. 4 and 5. Analogously to FIGS. 2 and 3, FIG. 4 shows the intermediate manufacturing step with the sacrificial layer 14 and FIG. 5 the final state with the sacrificial layer removed. Figure 4 shows that the bearing ring 9 is provided in the illustrated embodiment on all sides with the sacrificial layer 14, although he does not need this on its outer surface. In this way, the attachment of the sacrificial layer 14, for example by means of a dipping process, can be facilitated.

Again, the bearing ring 9 is first prepared, then the sacrificial layer 14 is mounted on this and then formed on this, the rotary tube 6, at least in the vicinity of the groove 10th

FIG. 5 shows the rotary bearing 7 with the sacrificial layer removed. It can be seen here that the bearing ring 9 in the groove 10 has not only inwardly a radial running surface to the rotary tube 6, but also in both directions axial running surfaces that require close fits, so that the sacrificial layer 14 so on the inner surface of the bearing ring. 9 and on whose faces is required.

According to the invention, therefore, one of the two bearing parts running on one another with bearing surfaces is first produced, on the bearing surface of which a sacrificial layer is applied, then the other part is molded onto these and then the sacrificial layer is removed. It then results in the two parts at a distance of the very narrow gap in which the sacrificial layer was, so with a very close fit.

Different production variants and material combinations are suitable: The successive bearing parts 12, 13 and 9, 6 may be made of metal. The sacrificial layer 14 may consist of a plastic. To remove the sacrificial layer, this plastic can be removed, for example, with a suitable solvent or burned at a higher temperature, which is still well tolerated by the metal.

In the case of the formation of the bearing parts of metal, the sacrificial layer can also be made of another metal, which can be removed, for example, with an acid is who does not attack the other metals. Also, metal coatings on plastic that are removable without the plastic attack are suitable

As the embodiments of FIGS. 2 and 3 as well as FIGS. 4 and 5 show, the sacrificial layer 14 is arranged there on the part of the bearing construction that surrounds the outside. However, it is also the reverse construction possible, in which the sacrificial layer, for example in the case of Figure 2 on the outer surface of the inner ring 13 and in the construction of Figure 4 on the surfaces of the groove 10 is arranged. The sacrificial layer is always placed on the running surfaces of a first of the two parts forming the bearing, and then the second of the parts is molded onto the sacrificial layer.

For the shaping different ways are possible. Preferably, an injection molding process is used. The formed part consists of plastic. In the case of FIG. 2, therefore, the inner ring 13 would consist of plastic and, in the case of the construction of FIG. 4, the rotary tube 6, at least in the region of the groove 10.

Metal casting methods are also useful if the sacrificial layer is suitably temperature resistant. Also, sintering methods can be used to produce molded parts.

Claims

Method for producing a rotary bearing CLAIMS

1. Method for producing a rotary bearing (7, 8) for the image sensor (5) and / or the objective (4) of a video-endoscope consisting of two parts (9, 6, 12, 13) running parallel to each other with running surfaces (1), characterized in that first a first of the two parts (12, 9) is made with its treads, that then the treads are coated with a sacrificial layer (14), that then on this the second of the two parts (13, 6) is formed with its treads and that finally the sacrificial layer (14) is removed.

2. The method according to claim 1, characterized in that the sacrificial layer (14) is removed by etching and / or dissolving.

3. The method according to any one of the preceding claims, characterized in that the shaping takes place by injection molding.

4. The method according to any one of claims 1 or 2, characterized in that the shaping takes place by sintering.