WO2015149754A1 - Computer-controlled machine tool for producing small workpieces - Google Patents

Abstract

The invention relates to a computer-controlled machine tool (1) for producing small workpieces, in particular for the field of dentistry, preferably from ceramic materials, metals, plastics, or waxes. The machine tool is made with a tool spindle (2) for receiving different tools (3), a tool motor (4) for driving the tool spindle (2), and a workpiece holding device (5) for receiving and holding a workpiece (6) to be machined. The workpiece holding device (5) can be positioned in or about three to five or more machining axes relative to the rotating tool (3). The machine tool also comprises a frame element on which the tool motor (4) and the workpiece holding device (5) are mounted by means of linear guides. The invention is characterized in that the frame element is designed in the form of a plane-parallel base plate (8), and two linear guides are arranged on the base plate (8) at intersecting angles. A tool spindle axis (2A) of the tool motor (4) is arranged at another angle relative to the remaining linear axes of the linear guides such that all spatial points at least within the provided workpiece (6) can be reached with the tool clamped in the tool spindle (2) by moving the three linear axes in a coordinated manner.

Description

 description

 Computer-controlled machine tool for the production of small

 workpieces

 Technical area

 The invention relates to a computer-controlled machine tool for the production of small workpieces, in particular in dental technology, jewelry production and microsystems technology, preferably of ceramic materials,

 Metals, plastics or waxes.

 State of the art

 CNC machine tools and machining centers with up to 5 axes have been known for some time and in many variants worldwide in use. Characteristic of this type of machine is that they are usually equipped with three linearly movable axes and two pivot axes. In this case, all axes can be realized "in the tool" (the workpiece is not moved), as well as all axes "in the workpiece" (the tool rotates only about its own axis, all spatial movements are performed by the workpiece), as well as any Combination of these axle arrangements.

 All common designs have in common that the machine build on a relatively complex, mostly cast frame member, which in turn requires a multi-sided, precise machining to give the machine the desired and necessary precision. This frame member causes a considerable part of the cost of the mechanical construction. An example of a machining center for the production of small workpieces in the dental field is described in DE 10 2010 035 669 AI.

 WO 2009/100863 describes a jig for a computer-controlled, cutting machine for the production of dental workpieces with a slidably mounted holding device on which a support plate is mounted for receiving a mold blank, wherein the support plate has at least one passage opening in which the Mold blank is arranged at least about an axis of rotation substantially parallel to the main plane of the support plate.

Presentation of the invention

 It is an object of the present invention, a machine tool as possible

 simple and inexpensive to build constructed, which is designed for the machining of small and very small workpieces.

According to the invention the object is achieved by the subject of claim 1 solved. Advantageous developments emerge from the dependent claims.

 It is an idea of the invention to provide a computer-controlled machine tool for the production of workpieces with a tool spindle for receiving various rotating tools, with a tool motor for driving the tool spindle and a workpiece holding device for receiving and holding a workpiece to be machined the workpiece holding device can be positioned relative to the rotating tool in or around three to five or more machining axes, with a frame element formed in the XY direction as a plane-parallel base plate, on which the tool motor and the workpiece holding device are mounted by means of first, second and third linear guides wherein the tool spindle is movable with a tool spindle axis in the Z direction by means of the first linear guide perpendicular to the X-Y plane of the base plate and angeord second and third linear guides on the base plate in an intersecting angle are net, so that all spatial points can be reached at least within the intended workpiece with the tool clamped in the tool spindle by coordinated movements of carriages on the three linear guides. This has the advantage that force flow paths, which occur during machining between the workpiece and the tool, are reduced to a minimum. The machine tool thus has a very high inherent rigidity with minimal

 Construction costs on. The machine tool can thus be designed to conserve resources and as easily as possible in terms of their weight.

 In order to produce a high rigidity of the frame member, wherein the power flow paths are minimized, a window, within which the tool spindle axis is movable in an X-Z plane, is formed in the frame member. The frame element therefore has a particular rectangular window opening. Thus, the tool spindle axis can be moved through the window opening to a three-dimensional machining of the workpiece controlled by positioning drives and moved in a Z-space axis.

 In order to design the power flow paths as optimally as possible and short and thus to produce a lightweight construction with high rigidity, the at least one linear guide of a carrier, in particular a spindle carrier, the workpiece holding device is arranged on a first front surface of the base plate designed as a frame member and the at least one linear guide the support of the tool spindle on a second, arranged to the first mirror-symmetrically opposite rear surface of the base plate.

Such a machine tool may preferably be used in dental technology, but also in the production of jewelery and in microsystems technology and be optimized specifically for a specific workpiece type. In dental technology can thus workpieces for dental prostheses such as crowns, bridges, pin teeth, implants, etc., for example, from presintered or organically bonded ceramic blanks without re-clamping machined on all sides. Furthermore, in such machine tools and plastics for temporaries or metals for metallic prostheses and waxes, for example, for the production of gold fillings, crowns and gold teeth by the Wachsaus fusion process. Likewise, the machines can of course also be designed and used for the processing of minerals, glasses and natural materials (such as wood, horn, bones, etc.), ie in total for practically all materials that can be machined. Due to the small workpiece size such machine tools can be so small, lightweight and handy that they can be operated without special technical or infrastructure requirements as a desktop device to a normal household socket (110 - 240 VAC, I _nominal 16 A).

 So that all points in space can be achieved in a particularly preferred cuboid processing space, two or three linear axes are each arranged at right angles to each other and thus parallel to the respective spatial axes of a Cartesian coordinate system (X-Y-Z) according to a further embodiment of the invention. Thus, the machine tool is easy and inexpensive to produce, and the power flow paths minimized and easy to calculate.

 It is understood that the three linear axes of the linear guides and the possibly

 another one or two degrees of freedom of the machine tool in not

 could be formed at right angles to each other arranged axes, if this brings advantages for the spatial structure of the machine, the design requirements or chip removal. In this case, the machine control takes over the conversion of the axis coordinate system into a particularly preferred Cartesian coordinate system, for example according to DIN 66025 / ISO 6983.

 In order to edit complex workpieces without re-clamping on more than one side, more preferably, the workpiece holding device considered in the initial position in any axis position include a first pivot axis, which is not formed parallel to the Z-axis axis rotatable. Since the tool spindle axis is preferably set in the Z-space axis, the workpiece holding device can take any other pivot axis different from the Z-space axis to achieve multi-sided machining of the workpiece.

 More preferably, the first, the workpiece moving axis of rotation is arranged parallel to the X-Y plane in the initial position considered. Thus, the workpiece is rotatable and evenly machinable from a front and back.

For better machinability of the workpiece, it is further preferred that the workpiece holder tevorrichtung to another arbitrary spatial axis, that is, a second, of the first pivot axis (40A) with a moving pivot axis, is pivotable, which is not formed parallel to the first pivot axis. This creates a fifth degree of freedom in terms of workpiece and tool.

 According to a further preferred embodiment, at least one spatial axis, in particular the Y-space axis, for moving the workpiece holding device with two parallel, as far as possible from each other remotely mounted linear guides is formed. Thus, the workpiece holding device of the machine tool is designed to be movable in a Y-axis parallel to the X-Y plane of the frame member.

 In order to secure and form the structure of the frame member, at least one spatial axis, in particular the X-space axis, formed for moving the tool spindle with two parallel, as far as possible away from each other mounted linear guides. Thus, the tool spindle is designed to be movable in an X-axis parallel to the X-Y plane of the frame member.

 In order to distribute the strength and the rigidity and the forces occurring well, at least one spatial axis, in particular the X-axis, is more preferably designed for moving the tool spindle with two parallel linear guides. Thus, the power flow paths are guided over two linear guides, wherein the parallel distance of the two linear guides comprises at least the defined width of the window opening.

 According to a further preferred embodiment, it is also preferable to divide the forces on two linear guides, at least one spatial axis, in particular the Y-axis, for moving the workpiece holding device with two parallel, in particular arranged at least in the defined movable distance of the X-axis axis, linear guides educated.

 The linear guides of the workpiece holding device and a support of the tool spindle can be arranged on a common surface of the base plate of the frame member. They may also be at right angles to each other, i. be arranged on the end face and on the side surface.

 To improve the machining of the workpiece, in particular for machining from all sides, i. Also, the back of the workpiece, the workpiece holding device is further preferably formed in the starting position on a workpiece carrier rotatable about the X-axis axis.

 For improved processing, the workpiece holding device is further preferably designed to be pivotable parallel to the linear guide in the Y-space axis about the Y-space axis. Thus, the workpiece can be processed better with a further degree of freedom.

To move the tools with high precision and thus a high-precision workpiece To produce, the machine tool comprises electrically controllable drives, particularly preferably positioning drives, servo drives or stepper drives, for moving tool spindle and workpiece holding device in the processing axes. These positioning drives are controlled by a computer via a control device and are particularly preferably multiaxially interpolatable so that the tool can describe arbitrary space curves with programmable path speed relative to the workpiece. The computer makes use of a machining program according to or based on DIN 66025 / ISO 6983, each time before the corresponding processing step completely or step by step transmitted to the machine control and of this in the predetermined time sequence in the movement commands for the individual positioning drives and the speed specifications is translated for the tool drive.

 According to an embodiment of the invention, the frame member is formed with feet for setting up the frame member in a vertical direction, in particular, the X-axis axis includes the vertical. A particularly advantageous chip removal and correspondingly low contamination of the spindle and the linear guides results in an arrangement in which the base plate parallel to a horizontal plane and the Z-axis (the tool spindle) is accordingly arranged vertically (hanging). Similarly, arrangements are possible depending on the design specification, space and requirements of the removal of chips and, if necessary, used cooling lubricants, in which the base plate is arranged in any solid angle to the horizontal.

 To improve the detection and removal of chips and auxiliary media such as cooling lubricants and for sealing the processing space to the outside and for reasons of machine safety, the machine tool is formed with an enclosure, in particular a trough-like geometry, in particular an extraction by means of vacuum and a bottom opening is provided.

 In order to create a fully automatic machine tool, the machine tool is preferably formed with a tool magazine, wherein the tools by means of controllable collet by the relative to the tool magazine in all three spatial directions movable tool spindle can be removed automatically and be deducted from the tool magazine. The tool magazine is arranged so that it can be reached by the tool spindle and thus allows an automatic tool change without additional components. A possible arrangement of the tool magazine is shown in FIGS. 1, 3 and 4.

Further preferably, the tool magazine is formed with an elastic element, in particular an elastomer element with bores, which are formed slightly smaller than the corresponding shanks of the tools, whereby the in the factory tool magazine stockpiled tools are held vibration safe in these holes, but also without the operation of actuators in the tool magazine can be removed or inserted through the collet.

According to the invention is therefore on an expensive, consuming to edit frame member, for example in the form of a casting omitted, with a plane-parallel base plate assumes the supporting function. The base plate is arranged perpendicular to the tool spindle axis in order to minimize the force flow paths and to increase the inherent rigidity, wherein the screwed linear guides of the machine tool can contribute substantially or partially to the rigidity of the plane-parallel base plate.

 Brief description of the drawings

 The invention will be explained in more detail below with reference to an embodiment with reference to drawings. Show it:

 Fig. 1 is a schematic plan view from below of the machine tool according to the invention;

 FIG. 2 is a front view of the machine tool according to the invention; FIG.

FIG. 3 shows a top view of the machine tool according to the invention; FIG.

4 shows a side view from the left of the machine tool according to the invention; and [0034] FIG. 5 shows a side view from the right of the machine tool according to the invention.

 Best way to carry out the invention

 Fig. 1 shows in an abstract representation in plan view from below a computer-controlled machine tool 1 according to the invention for the production of

 Workpieces, in particular for the production of dental prostheses, such as crowns,

 Bridges, pin teeth, implants, and other small workpieces, for example in jewelery production or microsystem technology.

 The machine tool 1 is thus particularly preferred for the production of

Workpieces made of ceramic materials, metals, plastics, waxes but also natural materials such as glass, minerals and natural materials (especially wood, horn, bone, etc.) are provided. The machine tool 1 comprises a tool spindle 2 with a collet chuck 9 for holding various tools 3 from a tool magazine 48 and a tool motor 4 for driving the tool spindle 2 and a workpiece holding device 5 for receiving and holding a workpiece 6 to be machined the starting position aligned with its tool spindle axis 2A perpendicular to the workpiece holding device 5. The machine tool 1 is formed with five machining axes. The tool motor 4 with the tool spindle 2 is parallel to the alignment of the tool spindle axis 2 A in a horizontal Z-axis axis by means of a Posi- tionier drive s 10 and a threaded spindle 13 precisely on a spindle carrier 15 by means of a first linear guide 12 movable.

As shown in Fig. 2 in a front view and in Fig. 3 in a plan view from above, the tool motor 4 is mounted for this purpose on a spindle carrier 15 with the first linear guide 12 on the opposite side of a workpiece. A carriage 14 running in and supporting the first linear guide 12 is fixed to a support 25.

 The machine tool 1 comprises a frame element which is in the form of plane-parallel

 Base plate 8 is formed. The plane-parallel base plate 8 is vertically positioned in the selected representation as shown in FIGS. 2, 4 and 5 with an alignment in the vertical X-axis axis. In this X-space axis, the tool motor 4 is movable over two parallel rails 22, 26 of a second linear guide 21 with carriages 24, 28 arranged thereon, as shown in FIG. 5 as a side view from the right. The respective height of the spindle carrier 15 is adjustable by means of a threaded spindle 23, which is controlled by a positioning drive 20. On a first front surface 82 of the base plate 8, the workpiece holding device 5 is arranged by means of a third linear guide 31 on a support with pivot arm 44 in a Y-axis axis displaced. The workpiece holding device 5 is mounted on a carriage 34 which runs on a rail 32 of the third linear guide 31. The exact position on the Y-axis axis is adjusted by means of a positioning drive 30 and a threaded spindle 33. The two linear guides 21 with rails 22, 26 are arranged on a second relative to the X-axis axis mirror-symmetrically opposite rear surface 84 of the base plate 8, as shown in FIG. 5 is more clearly.

 Thus, on the plane-parallel base plate 8, the second and third linear guides 21 and 31 are arranged at an angle crossing through 90 °, being arranged on two different opposite surfaces, once on the front surface 82 and once on the rear surface 84, whereas the tool spindle axis 2A is arranged parallel to the Z axis and perpendicular to the XY plane in which the base plate 8 is aligned. By virtue of this structure, the power flow paths occurring during machining of the workpiece 6 are minimized for a short time. Further, additional rigidity of the frame member is generated by the linear guides 21 in the direction of the X-space axis and the linear guide 31 in the direction of the Y-space axis.

The workpiece 6 with the workpiece support 5 is movable with three degrees of freedom on the front surface 82 of the base plate 8. On the carriage 34 of the linear guide 31, a Schwenkarmhalter 42 is mounted with a pivot arm 44. As shown in Fig. 2, on the Schwenkarmhalter 42 once a positioning drive 40 is mounted with a threaded spindle 43 to pivot the workpiece 6 together with the workpiece holding device 5 about the Y-axis axis at the bearing 45 and 46 in the pivot axis 40A. The swing arm 44 includes in the home position in the X-axis formed direction another, as shown in Fig. 2, positioning 50 to rotate the workpiece holding device 5 together with the workpiece 6 about the X-axis in the pivot axis 50A. Thus, the workpiece 6 can be machined from different sides, in particular from the front surface 82 and the rear surface 84, with the tool 3. The pivoting movement in the bearing 45 and 46 is carried out by means of rotation of a threaded spindle 43. The workpiece holding device 5 is mounted directly on the positioning drive 50. The positioning drive 50 and the other positioning drives 10, 20, 30 and 40 include depending on the design of an intermediate reduction gear.

 The power flow path between the tool 3 and the workpiece 6 according to the invention is small in this machine tool and designed to be extremely short on the frame member 8. The power flow path from the tool 3 thus passes over the tool spindle axis 2A and the tool motor 4 on the spindle 13, of the spindle 13 on the carrier 25 which is mounted on carriage 24 and 28 of the linear guide 21, wherein the forces on the rails 22 and 26 are transmitted. The forces are transmitted to the rear surface 84 of the base plate 8 and are transmitted via the strength and rigidity to the front surface 84 of the base plate 8. From there, the forces on the linear guide 31 on the Schwenkarmhalter 42, wherein the forces are divided here again on the spindle 43 and the bearings 45 and 46. These are forwarded to the pivot arm 44, the forces on the workpiece holding device 5 and the workpiece 6 transmits.

 So that the base plate 8 has a high rigidity and the tool spindle 2 in the spatial axes X and Z is movable, the base plate 8 has a rectangular window 86 through which the tool spindle 2 is moved with the tool 3 and the rectangular window 86th is elongated at least in the X-space axis, that the maximum travel in the X-space axis of the tool spindle 2 is movable.

 The tool motor 4 is mounted for this purpose with the linear guide rail 11 on the spindle carrier 15, which is moved by rotation of the spindle 13 in the Z-space axis through the window 86 directly to the workpiece 6 to edit the workpiece 6.

Also, the tools 3 are automatically removed from the tool magazine 48 by means of the electrically (or electropneumatically) actuated collet 9 and again stored. Thus, an automated tool change program controlled by the machine control can be performed. Thus, an automatic, means a computer controlled machining of the workpiece 6 feasible. The tool magazine 48 has for this purpose an elastic element with holes in which the tools 3 can be stored. The tool magazine 48 is arranged on the side on the pivot arm 44 of the workpiece holder 5 with the holes 49 parallel to the tool spindle axis 2A.

 The base plate 8 is installed in the vertical direction of the spatial axis X with a bottom with a geometric shape in the form of a trough 60, wherein the bottom 60 is inclined to an opening, not shown, in the trough 60, so that chips and optionally used cooling lubricants are removed , The discharge is promoted by means of negative pressure, generated in a discharge channel of the opening. The machine tool 1 is located in a housing, not shown, wherein the enclosure for sealing the processing space to the outside and to ensure the machine safety according to Directive 2006/42 / EC (or equivalent non-European requirements and guidelines) is provided and has no supporting function.

 All figures show only schematic, not to scale representations.

 Moreover, reference is made in particular to the drawings for the invention as essential.

Claims

claims  Computer-controlled machine tool (1) for the production of small workpieces  (6), in particular in the dental field, preferably made of ceramic materials, metals, plastics or waxes, with a tool spindle (2) for receiving various tools (3), with a tool motor (4) for driving the tool spindle (2) and a workpiece holding device ( 5) for receiving and holding a workpiece (6) to be machined, wherein the workpiece holding device (5) is positionable relative to the rotary tool (3) in or around three to five or more machining axes with respect to each other, in an XY direction, formed as a plane-parallel base plate (8) frame member on which the tool motor (4) and the workpiece holding device (5) by means of first, second and third linear guides are mounted, wherein the tool spindle (2) with a tool spindle axis (2A) in the Z direction by means of first linear guide (12) perpendicular to the XY plane of the base plate (8) is movable and second and third linear guides (21, 31) on the base plate (8) i n are arranged at an intersecting angle, so that by coordinated movements of carriages on the three linear guides (12, 21, 31) all points in space at least within the intended workpiece (6) can be reached with the tool clamped in the tool spindle (2), wherein a frame (86) within which the tool spindle axis (2A) is movable in an XZ plane is formed in the frame member, and a support of the workpiece holding device (5) is arranged on a first front surface (82) of the frame member (8) is and a spindle carrier (15) of the tool spindle (2) on a second, the first front surface (82) mirror-symmetrically opposite rear surface (84) of the base plate (8) is arranged.  Machine tool (1) according to claim 1, characterized in that two or three linear axes are arranged at right angles to each other and thus parallel to the respective spatial axes of a Cartesian coordinate system (X-Y-Z).  Machine tool (1) according to claim 1, characterized in that the workpiece holding device (5) in any arbitrary axis position, a first  Swivel axis (40A) includes, which is not formed parallel to the Z-axis axis rotatable.  Machine tool (1) according to claims 1 and 3, characterized in that the first, the workpiece (6) moving pivot axis (40A) is arranged viewed parallel to the X-Y plane in the initial position. Machine tool (1) according to claim 1 and 3, characterized in that the workpiece holding device (5) to a further arbitrary spatial axis, ie a second, of the first pivot axis (40A) with a moving pivot axis (50A) is pivotable, which is not parallel to the first pivot axis (40A) is formed.  Machine tool (1) according to claims 1, 3 and 4, characterized in that the second, the workpiece (6) pivoting pivot axis (50A) is particularly preferably arranged at right angles to the first pivot axis (40A).  Machine tool (1) according to one of claims 1 to 4, characterized in that at least one spatial axis, in particular the X-axis, for moving the tool spindle (2) formed with two parallel, as far as possible from each other remotely mounted linear guides (21) is, in particular at least one spatial axis, in particular the Y spatial axis, for moving the workpiece holding device (5) with two parallel, as far as possible from each other remotely mounted linear guides (31) is formed.  Machine tool (1) according to one of claims 1 to 8, characterized in that the machine tool (1) with electrically controllable drives (10, 20, 30, 40, 50), particularly preferably servo drives or stepper drives, for moving tool spindle (2) and workpiece holding device (5) is formed in the processing axes.  Machine tool (1) according to one of claims 1 to 9, characterized in that the machine tool (1) with an enclosure, in particular a trough-like geometry (60), for the detection and removal of chips and auxiliary media such as coolants and lubricants Seal the processing space is formed to the outside, in particular an extraction by means of negative pressure and a bottom opening is provided.  Machine tool (1) according to one of claims 1 to 10, characterized in that the machine tool (1) with a tool magazine (48) is formed, wherein tools (3) by means of controllable collet chuck (9) by the relative to the tool magazine ( 48) in all three spatial directions movable tool spindle (2) automatically from the tool magazine (48) can be removed and deducted, wherein in particular the tool magazine (3) with an elastic element, in particular an elastomeric element with holes (49) is formed, which is slightly smaller as the corresponding shanks of the tools (3) are formed, whereby in the tool magazine (48) stockpiled tools (3) in these holes (49) are held vibration safe, but also without the actuation of actuators in the tool magazine (48) by the collet ( 9) can be removed or inserted, wherein in particular the tool spindle axis (2A) in a spatial axis Z parallel to the XZ plane of the frame element ver is designed mobile.