DENTAL MILLING MACHINE

Abstract

A dental milling machine comprising a workpiece holder (2) and a changer arm (10) is characterized in that the changer arm (10) has a substantially U-shaped gripping attachment (12) and in that a tool (14) of the dental milling machine (1) has a tool fixation element (16). The tool fixation element has grooves (18) or holding projections at two mutually opposed positions which face away from each other, over which grooves or holding projections the U-shaped gripping attachment (12) of the changer arm (10) can engage, wherein parts of the U-shaped gripping attachment (12), more particularly the side flanks (12a, 12b) of the U-shaped gripping attachment (12), make contact with the grooves (18) or holding projections of the tool fixation element (16) under preload.

Claims

1. A dental milling machine comprising a workpiece holder (2) and a changer arm (10) carrying the workpiece holder (2), wherein the changer arm (10) has a substantially U-shaped gripping attachment (12) and wherein a tool (14) of the dental milling machine (1) has a tool fixation element (16) which has grooves (18) or holding projections at two positions which are spaced apart from each other, and over which grooves or holding projections the U-shaped gripping attachment (12) of the changer arm (10) is configured to engage, wherein parts of the U-shaped gripping attachment (12) make contact with the grooves (18) or holding projections of the tool fixation element (16) under preload, or wherein the tool fixation element (16) is held clamped inside the U-shaped gripping attachment (12).

2. The dental milling machine according to claim 1, wherein the changer arm (10) further has a clamping chuck (6) for receiving a workpiece holder (2) of a workpiece (4).

3. The dental milling machine according to claim 1, wherein the changer arm (10) carries two mutually adjacent U-shaped gripping attachments (12) which are spaced apart from each other.

4. The dental milling machine according to claim 3, wherein the U-shaped gripping attachments (12) have open sides which open sides are oriented opposite to each other, wherein the U-shaped gripping attachments (12) are directed towards each other with their open sides, but are displaced in relation to each other.

5. The dental milling machine according to claim 1, wherein the grooves (18) or holding projections are attached to a ring of the tool fixation element (16) which is fixed to the tool (14), and wherein the grooves (18) are circular in shape.

6. The dental milling machine according to claim 4, wherein the changer arm (10) has first flexible tongues (12c, 12d), and wherein the first flexible tongues (12c, 12d) are flexible at one end and are mounted at another end, and wherein when the changer arm (10) of the dental milling machine (1) approaches a tool which is clamped inside a clamping chuck (22) or a collet chuck of a tool spindle (24) of the dental milling machine, the first flexible tongues (12c, 12d) are configured to fixedly attach the tool (14) by pressure exerted onto the first flexible tongues (12c, 12d).

7. The dental milling machine according to claim 6, wherein the collet chuck or the clamping chuck (22) of the tool spindle (24) grips and holds a shank (19) of the tool (14).

8. The dental milling machine according to claim 6, wherein the tool fixation element (16) is shaped as a circular sleeve and the tool (14) is substantially pin-shaped, wherein a maximum outside diameter (D1) of the groove (18) of the tool fixation element (16), which is substantially circular in a cross section, is maximally 0.5 mm larger than an inside diameter (D2) of the first flexible tongues (12c, 12d) in an unloaded state, and wherein the groove (18) or a first annular cavity (32) on the tool fixation element (16) is designated for gripping the collet chuck or the clamping chuck of the changer arm (10).

9. The dental milling machine according to claim 8, wherein the tool (14) has a second groove (18) or a second annular cavity (34) which is arranged to be spaced apart from an axial end section (2a) of the tool.

10. The dental milling machine according to claim 8, wherein the ring of the tool fixation element (16), between the first groove (18) or the first annular cavity (32) and the second groove (18) or the second annular cavity (34), has an annular bridge (33) which is substantially circular in a cross section, wherein a diameter of the substantially circular annular bridge (33) is larger than the diameter of at least one of the annular bridges which confine the first and second annular grooves (18) or annular cavities (32, 34), respectively, each at sides of the first and second annular grooves (18) or annular cavities (32, 34), respectively, which are positioned opposite of the substantially circular annular bridge (33).

11. The dental milling machine according to claim 17, wherein the changer arm (10) carries a sheet (36) at the end of which the U-shaped gripping attachment (12) is provided, wherein the side flanks (12a, 12b) of the U-shaped gripping attachment (12) have two flexible tongues (12c, 12d) which are spaced apart from each other.

12. The dental milling machine according to claim 11, wherein the two flexible tongues fit into annular cavities (32, 34) and fill the annular cavities (32, 34) in a substantially U-shaped fashion.

13. The dental milling machine according to claim 12, wherein the flexible tongues (12c, 12d) have a length which is larger than a radius of the annular cavities (32, 34) and which partly encompasses the annular cavities (32, 34).

14. The dental milling machine according to claim 11, wherein the U-shaped gripping attachment (12) has flexible tongues (12c, 12d) with a width distinctly smaller and with an elasticity distinctly higher than a width and elasticity of the sheet (36), which sheet is flexible, which flexible tongues (12c, 12d) are spaced apart from each other.

15. The dental milling machine according to claim 1, wherein the changer arm (10) is movable in a direction of movement of substantially 90 degrees in relation to a longitudinal extension of the tool (14) and is configured to grip the tool in the grooves (18) via flexible tongues and remove the tool from the clamping chuck (22) and supply the tool to a tool magazine at which a further, correspondingly equipped tool may be taken up by the changer arm (10).

16. The dental milling machine according to claim 15, wherein the changer arm (10) is movable such that a tool (14) accommodated inside the U-shaped gripping attachment (12) may be positioned in front of a receptacle slot of the tool magazine such that the tool (14) is configured for insertion into the receptacle slot of the tool magazine with the groove (18) or annular cavity (32, 34), and wherein a side flank of the receptacle slot of the tool magazine is configured to act against a lateral movement of the tool (14) inside the receptacle slot in case of a lateral movement of the changer arm (10) at an angle of substantially 90 degrees in relation to a direction of movement of the changer arm (10) during the insertion of the tool (14) into the receptacle slot of the tool magazine.

17. The dental milling machine according to claim 1, wherein parts of the U-shaped gripping attachment (12) that make contact with the grooves (18) or holding projections of the tool fixation element (16) comprise side flanks (12a, 12b).

18. The dental milling machine according to claim 3, wherein the two mutually adjacent U-shaped gripping attachments (12) extend in a same plane.

Description

[0036] Further advantages, details and features may be taken from the subsequent description of a number of exemplary embodiments with the help of the attached drawings, which show:

[0037] FIG. 1 a schematic depiction of a dental milling machine in one embodiment of the invention;

[0038] FIG. 2 an enlarged depiction of a detail from FIG. 1;

[0039] FIG. 3 another enlarged depiction corresponding to FIG. 2;

[0040] FIG. 4 a depiction of another embodiment of a dental milling machine in accordance with the invention;

[0041] FIG. 5 a further depiction of a detail of the embodiment according to FIG. 4.

[0042] From the embodiment according to FIG. 1, a part of a dental milling machine 1 is visible. Dental milling machine 1 is designed for machining a workpiece 4.

[0043] For this purpose, workpiece 4 has a workpiece holder 2 which is held clamped inside a clamping chuck 6 of a changer arm 10 of dental milling machine 1. Changer arm 1 is movable in five spatial directions in the exemplary embodiments depicted, which is, in three translational and two rotary spatial directions.

[0044] Laterally, which is, outside the axis of clamping chuck 6 and workpiece 4, it carries a U-shaped gripping attachment 12.

[0045] U-shaped gripping attachment 12 is designed for receiving a tool 14 and to fixedly attach it. For this purpose, tool 14 has a workpiece fixation element 16 whose details are described further below.

[0046] Workpiece fixation element 16 has two adjacent annular grooves 18. These are shaped to be radially annular and are coaxial in relation to tool 14, and are in addition spaced apart from each other viewed in an axial direction.

[0047] Tool 14 additionally has a shank 19. This is designed for being held clamped inside a clamping chuck 22 of a spatially fixed tool spindle 24.

[0048] Tool fixation element 16 extends between an axial end portion 2a (cf. FIG. 2), which is designed for the machining executed by the tool, and shank 19 of tool 14.

[0049] From FIG. 1, a tool 14 is visible which is held clamped inside clamping chuck 22 of spindle 24, as well as a further tool which is attached to U-shaped gripping attachment 12. The orientation of these two tools 14 is opposite to each other.

[0050] When tool 14 is to be removed from spindle 24, tool 14 which is positioned inside gripping attachment 12 must first be taken to a tool magazine, such that gripping attachment 12 is free of the tool.

[0051] When this has been completed, changer arm 10 may then first be rotated by 180 degrees around what is referred to as the B-axis, i.e. the rotational axis of clamping chuck 6.

[0052] Gripping attachment 12 then extends laterally next to tool fixation element 16 of tool 14 which is clamped inside the spindle.

[0053] The orientation is performed in such a fashion that the U extends precisely at the altitude of upper ring 18 of the fixation element.

[0054] By means of a lateral motion, the gripping attachment is then pushed onto this annular groove 18. Clamping chuck 22 is loosened, and changer arm 10 is moved upwards, such that spindle 24 is without a tool.

[0055] Changer arm 10, in turn, is then rotated into the position according to FIG. 1, and the tool which is now positioned there is pushed from spindle 24 and into a free receptional position of the workpiece magazine, which is done with the help of the other annular groove 18 which has now turned out to be positioned on top after changer arm 10 has been rotated by 180 degrees.

[0056] From FIG. 2, the axial distance of both annular grooves 18 and the arrangement are visible in detail.

[0057] An enlarged depiction of tool 14 clamped inside spindle 24 is visible from FIG. 3. Fixation element 16 beginsviewed starting from axial end portion 2awith a chamfer 28. Subsequent to this, there is the multiple arrangement of annular grooves 18. In the embodiment according to FIG. 3, an annular cavity 32 is provided. In the axial direction adjacent to this, there is an annular bridge 33, and then, as the second annular groove 18, a second annular cavity 34. Subsequent to this, shank 19 of the tool is provided.

[0058] A further embodiment of a dental milling machine in accordance with the invention is visible from FIG. 4.

[0059] In this embodiment, two gripping attachments 12 are provided, which is, at one mutual sheet 36 which is attached to changer arm 10. Each gripping attachment has flexible tongues 12c and 12d which form part of the U. Flexible tongue 12c has a side flank 12a, and flexible tongue 12d a side flank 12b. Side flanks 12a and 12b face towards each other.

[0060] As is visible from FIG. 4, the central leg of the U each has an internal radius, adapting it to the shape of annular grooves 18.

[0061] Additionally, one central slot 38 is provided for each, which improves the flexibility of flexible tongues 12c and 12d.

[0062] It is to be understood that the precise configuration may be adapted to the requirements in any fashion. What is essential, however, is the possibility of fixedly attaching annular grooves 18 of tool fixation element 16 inside gripping attachments 12. If necessary, small projections which face inwards and which, if applicable, further improve the clamping and make possible a snapping in as well, may also be provided at side flanks 12a and 12b which are arranged at the edges.

[0063] This is visible from FIG. 5, which Figure shows the projections 40 facing inwards.

[0064] Due to these projections, the wrap-around angle of gripping attachment 12 is slightly larger than 180 degrees each.

[0065] From FIG. 5, central slot 38 is visible too. For the improvement of the spring characteristics of flexible tongues 12c and 12d, moreover, additional slots 42 and 44 are provided at the sides of the central slot.

[0066] As is visible from FIG. 5, sheet 36 is sistered in part. This increases the stiffness in the direction of the axis of tool 14, but still allows the desired spring characteristics, wherein sistering is dispensed with in the area of flexible tongues 12c and 12d.