Patent Application
20060105290
The invention relates to a holder for a tooth model for scanning the tooth model, comprising a work holding component to accommodate the model and a shaft connected to the work holding component for attachment thereof to a mount of a scanning device, which shaft shaft exhibits a coupling component comprising a cone. The invention also relates to a mounting device for a holder of the type mentioned above, which mounting device exhibits a mandrel in the form of a counter cone adapted to accommodate the holder.
The prior art includes holders for tooth models for use when tooth models are to be scanned. Depending on the scanning method employed as well as on the size of the tooth model to be scanned, there are holders that are designed for holding a single tooth model and others that can hold an entire mandibular cast.
It is often desirable to scan a single tooth model from several directions at the same time. To this end, the prior art discloses holders which are rotatable relatively to the image detecting unit. The company etkon AG distributes scanning devices, which have holders that are securely mounted on the equipment and can be rotated relatively to the image detecting unit. The holders contain a plastic modeling material, to which the tooth models to be scanned are fixed. The rigid attachment of the holders in the device is a disadvantage with this approach. Also, Sirona Dental System GmbH sells pot holders that can be fastened by means of a screwed mounting device so that they can be rotated on a mounting device. The assembly and disassembly of such a holder requires increased effort.
Patent application DE 195 47 137 A1 discloses a device for holding tooth and/or jaw model parts, in which a model supporting plate is fastened to a baseplate. This attachment is effected, on the one hand, by means of a counterpart of ferromagnetic material and, on the other hand, by concentric shaped guide means between the baseplate and the model supporting plate.
Patent application DE 34 11 363 A1 discloses a dentition model for the fabrication of dental prosthetic items. The tooth stumps of modeling material can be attached to a base by means of pins that are aligned at right angles to the axis of the tooth.
Patent application DE 100 49 186 A1 discloses a dental model base plate made of gypsum having a U-shaped groove for the insertion of tooth models.
It is thus an object of the invention to provide a holder for a tooth model that enables simple, secure, and precise attachment and positioning of the holder in the scanning device, and that is dirt proof and lowers production costs.
According to the invention, this object is achieved by a holder as defined in claim 1 and also by a mounting device as defined in claim 10.
The holder of the invention for holding a tooth model for scanning the tooth model contains a work holding component to accommodate the tooth model and a shaft connected to the work holding component for attachment to a mount on a scanning device, which shaft exhibits a coupling component comprising a cone. The holder comprising the cone can be fitted over an appropriately designed mount of a scanning device such that the holder is fixed both axially and radially in the required direction on account of the geometry of the cone such that a very good friction lock exists between the mount and the holder. This ensures that the tooth model to be scanned will maintain a radially fixed position during rotation.
Advantageously, the cone is in the form of an inner cone that is disposed on that end of the shaft that is remote from the work holding component. One advantage of the design of the cone as an inner cone is that the counterpart can be designed as an outer cone, while another advantage is that no dirt can collect on the tapered counterpart pointing upwardly.
Advantageously, the work holding component, the shaft, and the coupling component are axially symmetrical. In this way there is no preferential direction involved when mounting the tooth model on the holder, and the holder can be mounted in arbitrary orientation in the mounting device of the scanning device.
Advantageously, the cone has an angle of taper between two and nine degrees. An angle of taper which is too large results in a poor frictional connection and one that is too small impairs centering.
Advantageously, there is a centering section in the inner cone. Such a centering section can, for example, be formed by a cylindrical cavity adjoining the conical region. This ensures even better centering of the holder on the mount.
Advantageously, the shaft is resilient in the region of the cone. This makes it possible to improve the frictional connection between the holder and the mount.
Such elasticity can be achieved by a slit provided in the shaft in the region of the cone.
Advantageously, the work holding component for the tooth model is in the form of a small pot. Such a holder allows for a large number of different mounting options.
Advantageously, this small pot contains a reshapeable compound to which the tooth model can be fixed. This makes it possible to releasably attach a tooth model to be scanned while it is held in the holder sufficiently securely for scanning purposes and at the same time provides the option of manual correction of its position.
A further object of the invention is a mounting device for a holder, as has been revealed above. The mounting device exhibits a mandrel over which the holder can be fitted, which mandrel is designed as a counter cone to the cone of the holder, in particular as an outer cone. Such a mounting device enables very simple, secure, and accurate attachment of the holder thereto.
Advantageously, the mandrel is spring-mounted, the spring travel of the mandrel being limited by a stop. When mounting the holder onto the mandrel the mandrel gives way to an extent depending on the force used to mount the holder and hits the stopper when the intended mounting force has been reached. Subsequent mounting is always effected with the same constant force, so that the holder is always mounted in the same position.
Advantageously, the angle of taper of the mandrel is equal to the angle of taper of the holder within a tolerance of one degree or less. This ensures a secure fit of the holder on the mandrel and provides maximal friction surface.
Advantageously, the mandrel is equipped with a centering pin, which adjoins the cone. This makes it possible to achieve even more accurate positioning of the holder.
The holder of the invention is explained below with reference to the drawings, in which:
When mounting the holder 1 onto the mandrel 8, a force acting in the axial direction is exerted on the mandrel 8, which results in the spring 9 being compressed. The mandrel 8 gives way in accordance with the applied force until its underside 13 hits a stop 14. The force required to push the holder 1 onto the mandrel 8, up to the point of its hitting the stop 14, is always the same. This means that the holder 1 will always be pushed onto the mandrel 8 by a defined force.
The angle of taper is selected such that a friction lock is created between the holder 1 and the mount in the form of a mandrel 8. The adhesive force FH between the conical part of the mandrel (10) and the conical coupling component (6) resulting from the action of the normal force FN is greater than the components of the traction force F′ produced along the cone during the production of rotational images.
Advantageously, the conical coupling component (6) can be of resilient design, in order to increase the normal force FN acting on the surface, and thus to increase the adhesive force FH.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 054 880.3 | Nov 2004 | DE | national |
