Vibration-isolating measuring instrument holder

Abstract

Measuring instrument holder for holding a measuring instrument (6) on a machine tool, with a first section (1, 31, 41, 51, 61, 71, 81) to be attached to a tool holder of the machine tool; a second section (2, 32, 42, 52, 62, 72, 82) receiving the measuring instrument (6); wherein the first section (1, 31, 41, 51, 61, 71, 81) and the second section (2, 32, 42, 52, 62, 72, 82) are connected to one another by a spring section (3, 33, 43, 53, 63) such that the second section (2, 32, 42, 52, 62, 72, 82) and the measuring instrument (6) to be attached to the second section are at least partially vibration-isolated from the first section (1, 31, 41, 51, 61, 71, 81) to be attached to the machine tool in at least one orientation, characterized in that the first section (1, 31, 41, 51, 61, 71, 81) is provided for receiving on a standardized tool holder of a machine tool and has a shape which is suitable for fastening adapted to a hollow shank taper, steep taper interface, or has the shape of a VDI shank.

Description

background

[0001] A vibration-isolating measuring instrument holder for mounting a measuring instrument on a machine tool is described. In particular, a measuring instrument holder with a spring section is described.

[0002] By using measuring instruments, such as touch probes, tools or workpieces can be measured in a machine tool. The machine tool's travel axes are used as measuring axes. When, for example, a touch probe is moved towards a workpiece, it emits a switching signal as soon as it touches the workpiece. A machine tool control system can detect this switching signal and then read out the current axis positions and calculate them against stored calibration values. Measuring instruments are usually attached to the machine tool with the help of an adapter, a so-called tool holder or measuring instrument holder, and are kept ready, for example, in a tool turret. This means that the measuring instrument remains unused in its turret position during machining operations.During machining, high, time-varying cutting forces can act on the tool, which are transmitted to the machine tool and tool turret in the form of oscillations or vibrations. Despite the high rigidity and high mass of the tool turret, the measuring instrument is sometimes exposed to extremely strong oscillations / vibrations. The oscillation / vibration load is particularly high during machining with interrupted cuts or when the tool is excited to natural frequency oscillations. Measurements have shown that the oscillations / vibrations can reach peak values ​​of over 100 g at a wide range of frequencies.

[0003] While these vibrations are generally not critical for the tools mounted in the tool turret, they can lead to damage to the measuring instruments. For example, measuring probes contain a battery power supply, electronics, and a mechanical measuring mechanism. The resulting vibrations can damage or destroy these components, leading to premature failure of the measuring instruments and the need for replacement.

[0004] It is known from the prior art that the forces occurring during machining lead to vibrations of the tool and the tool holder, and that such vibrations impair machining accuracy. Therefore, efforts are being made to reduce tool vibrations during machining.

[0005] For example, document DE 10 2004 019 869 A1 discloses a vibration-damped tool holder. This comprises a coupling structure for coupling to a machine tool and a clamping shank with a clamping structure for receiving a tool. Furthermore, the tool holder has a clamping arrangement that exerts a clamping force on the tool holder with a clamping force component acting in the axial direction.

[0006] Document DE 102 39 670 A1 also discloses vibration-damped forming tools. The tool has a cavity that is completely or partially filled with a mixture of a liquid and discrete particles of a solid, whereby the damping behavior of the tool can be influenced by varying the internal pressure in the cavity.

[0007] Document CH 680 089 A5 describes a holder for a measuring probe with a movable protective tube. Document DE 10 2007 043 030 A1 describes a tool holder and a measuring probe with a tool holder. This tool holder comprises a material section that differs from the usual base material in that it has a lower coefficient of linear expansion and / or lower thermal conductivity.

[0008] Document US 2013 / 0 200 248 A1 relates to a pneumatic vibration isolation mount for supporting a payload on a moving aircraft or helicopter while suppressing the transmission of vibrations in the 1 to 50 Hz band between the mount and the payload. The vibration isolation mount can be deployed in a towed carrier or airborne probe and powered by electrical power from the aircraft, making it a suitable platform for airborne geophysical instruments. It also has particular application in airborne electromagnetic surveys operating in the same frequency band, as it suppresses sensor vibrations that lead to noise generated by the modulation of the sensor coupling with the Earth's magnetic field.Furthermore, the invention can be constructed from resistive composite materials and non-magnetic metals so that it can be operated without significantly changing the ambient electromagnetic field to be measured.This vibration dampening system has a cylinder with a first coupling joint, a second coupling joint, and a piston separating an upper chamber and a lower chamber; a first pressure regulator in communication with an air supply and the upper chamber to maintain a first pressure in the upper chamber; a second pressure regulator in communication with the air supply and the lower chamber to maintain a second pressure in the lower chamber; an upper accumulator capable of holding compressed air in communication with the upper chamber; a lower accumulator capable of holding compressed air in communication with the lower chamber; wherein the first coupling joint couples the cylinder to a frame, and the second coupling joint couples the cylinder to a basket connectable to a payload.An interaction of the piston with the first pressure in the upper chamber and the second pressure in the lower chamber isolates vibrations of the frame from the basket. problem

[0009] The challenge is therefore to better protect a measuring instrument mounted in a machine tool's tool turret from oscillations / vibrations. At the same time, high measurement accuracy must be ensured. Proposed solution

[0010] As a solution, a measuring instrument holder for holding a measuring instrument on a machine tool is proposed, comprising a first section to be attached to a tool holder of the machine tool and a second section receiving the measuring instrument, wherein the first section and the second section are connected to one another by a spring section such that the second section and the measuring instrument to be attached to the second section are at least partially vibration-isolated from the first section to be attached to the machine tool in at least one orientation.

[0011] The spring section can increase the elasticity of the measuring instrument holder, so that the second section and the measuring instrument attached to it form a separate oscillating system. If the masses and spring stiffnesses are appropriately coordinated, this system can oscillate independently of the machine tool. The elasticity of the spring section can therefore decouple the measuring instrument from the machine tool to a certain extent. However, if the elasticity of the spring element is chosen to be too great, i.e. the spring element is too "soft", the measuring accuracy of the measuring instrument can be impaired. For example, if the connection is too soft, the entire measuring instrument holder and not just the measuring probe is deflected when using a measuring probe. This means that the measuring probe can only "detect" the switching point with a delay.On the other hand, too little elasticity can lead to insufficient vibration isolation.

[0012] The properties of the spring section can be selected so that different spring stiffnesses are provided for different orientations. For example, a higher spring stiffness can be provided for the X and Y directions than for the Z direction. Accordingly, the measuring instrument can be more effectively decoupled from vibrations oriented in the Z direction.

[0013] Here, "at least partially vibration-isolated" means that the spring stiffness of the spring section is selected depending on the excitation frequencies occurring and the mass of the second section and the measuring instrument to be attached to it in such a way that the vibration load on the measuring instrument is at least lower than with a rigid connection of the measuring instrument. The vibrations of the machine tool can also be completely suppressed.

[0014] The solution presented here for a measuring instrument holder for holding a measuring instrument on a machine tool is characterized in that the first section is provided for mounting on a standardized tool holder of a machine tool, wherein it has a shape that is adapted for attachment to a hollow shank taper, steep taper interface or has the shape of a VDI shank.

[0015] To solve the problem, a method for measuring a workpiece in a machine tool is also proposed. The measuring instrument is provided in a tool turret of a machine tool, with the measuring instrument mounted in a measuring instrument holder. The measuring instrument holder is conveyed to a working position of the machine tool. The measuring instrument holder is controlled so that the measuring instrument holder changes from a rest position to a measuring position. The desired parameters are then recorded in the measuring position. The measuring instrument holder is then conveyed away from the working position.

[0016] The measuring instrument holder can be controlled mechanically, electrically, pneumatically, or hydraulically. For example, an actuator can be provided in the measuring instrument holder that can be moved by the control.

[0017] The measuring instrument holder can also be controlled after the parameters have been recorded, so that the measuring instrument holder switches from the measuring position back to the rest position. However, the switch from the measuring position back to the rest position can also occur automatically, for example, via a return spring. Designs and properties of the measuring instrument holder

[0018] The first section and the second section of the measuring instrument holder can be formed from one part or from two parts. If the first and the second section are formed from one part, i.e. in one piece, the spring section can be formed by at least one recess in the one-piece holder, wherein the at least one recess forms the spring section and separates the first and second sections. If the first and the second section are formed from two separate parts, the spring section can be formed by at least one recess in the first and / or the second section. Furthermore, the spring section can also be formed as a separate part and attached to the first and / or the second section with a detachable or non-detachable connection.

[0019] The spring stiffness of the spring section can be varied. For example, the available vibration displacement can be made adjustable by a variable vibration gap. For example, adjusting screws can be provided to adjust the vibration gap and thus the vibration displacement. The free spring length could also be varied by an adjustable support. By shortening or lengthening the free spring length, for example by moving a support, the spring stiffness of the spring section can be increased or decreased. With a higher spring stiffness, the natural frequency can be shifted to higher frequencies while maintaining the same mass. Correspondingly, with a lower spring stiffness, the natural frequency can be shifted to lower frequencies.

[0020] The first and second sections can further be connected to one another by at least one damper. The dampers can brake relative movements between the first and second sections through friction, with the kinetic energy being converted into heat. The damper can be, for example, a metal or plastic ring, wherein the material used has an inherent damping that is greater than the inherent damping of the first and / or second section or of the material used therefor. The dampers can be formed from aluminum, copper, or alloys of these metals. In addition, the dampers can be formed from plastic, in particular from elastic plastics, such as elastomers, wherein the elastomers can comprise, for example, rubber.

[0021] In order to change the damping properties of the system, inserts and in particular damping inserts can also be provided.

[0022] Cavities sealed by sealing rings can exist between the first and second sections. With a suitable choice of material, for example, through the use of elastomer sealing rings, the sealing rings can also have a damping effect. The cavities can be partially or completely filled with oil, grease, liquids, or powder, with the damping being modified by filling the cavities. For example, the cavities can be filled with quartz sand or plastic powder. Mixtures, such as powder-liquid mixtures, can also be used.

[0023] At least one vibration damper can be provided. The vibration damper(s) can be attached to the measuring instrument and / or the second section. In particular, vibration dampers can be attached at points where the greatest deflection is expected. In a simple design, vibration dampers can be formed from an elastomer ring and a ring mass, with the elastomer ring having both damping and spring properties.

[0024] Furthermore, an additional mass can be provided. This additional mass can shift the natural frequency of the second section and the measuring instrument attached to it to lower frequencies. The additional mass can be connected to the second section and / or the measuring instrument rigidly or via elastic connections.

[0025] The measuring instrument holder can have a rest position and a measuring position, wherein in the rest position, the second section can be at least partially vibration-isolated, and in the measuring position, a spring-loaded connection can exist between the first section and the second section. The measuring instrument holder can thus be switched between two positions, with the rest position focusing on vibration protection of the measuring instrument, and the measuring position focusing on measurement accuracy.

[0026] A hydraulically, pneumatically, or electrically driven actuator can be provided to switch between the rest position and the measuring position. If the measuring instrument holder is mounted in the tool holder of the machine tool, the actuator can be connected to a voltage or pressure source that can be switched by a control system of the machine tool. A return spring can be provided to preload the measuring instrument holder in the rest position. The return spring can be made of metal or an elastomer. The distance between the rest position and the measuring position can be a few tenths of a millimeter. For example, the return spring can lift the second section between 100 µm and 900 µm from the first section.

[0027] In the rest position, the first and second sections can be resiliently connected to each other by sealing rings or elastic elements.

[0028] In the measuring position, a backlash-free connection can exist between the first and second sections. This connection can be formed by face gears provided on the first and second sections or by balls and prismatic grooves, each of which is pressed against the other by the actuator. In the measuring position, the sealing rings and elastic elements can continue to connect the first and second sections, but the properties of the connection are essentially determined by the rigid connection.

[0029] The first section has a shape that allows the measuring instrument holder to be attached to a tool holder / tool ​​interface of a machine tool. The first section has a shape that is suitable for attachment to a standardized tool holder. The first section is adapted to the shape of a so-called hollow shank taper or steep taper interface, or the first section has the shape of a so-called VDI shank. Brief description of the drawings

[0030] Further objects, features, advantages and possible applications will become apparent from the following description of non-limiting embodiments and the accompanying drawings. Fig. 1 shows a section through a first embodiment; Fig. 2 shows a first section of the Fig. 1 shown measuring instrument holder; Fig. 3 shows a section through a second embodiment; Fig. 4 shows a third embodiment; Fig. 5 shows a section through a fourth embodiment; Fig. 6 shows a section through a fifth embodiment; Fig. 7 shows a measuring instrument holder with an additional mass; Fig. 8 shows a measuring instrument holder with a vibration absorber. Detailed description of implementation examples

[0031] The Fig. 1 and Fig. 2 show a first embodiment of a measuring instrument holder. In addition, Fig. 1 shows a measuring instrument 6 attached to the measuring instrument holder. Fig. 1 only the measuring instrument holder is shown as a sectional drawing, but not the measuring instrument 6. The double arrows labelled "X" and "Z" indicate the X and Z axes of the measuring instrument holder. The Y axis, which extends perpendicular to the plane of the drawing, is shown in the Fig. 1 not shown.

[0032] The measuring instrument holder comprises a first section 1 and a second section 2. The first section 1, which is intended for mounting on a tool holder of a machine tool (not shown in the figures), encloses a part of the second section 2. The second section 2 is connected to the first section 1 via several spring fingers 3. As can be seen from Fig. 2, a total of six spring fingers 3 are provided. The spring fingers 3 are arranged essentially in a plane running perpendicular to the Z-axis. A gap is provided between the spring fingers 3 and the first section 1, which gap enables movement of the spring fingers 3 relative to the first section 1. The spring fingers 3 comprise a radial section 3a which runs outwards from a central region 3b. There, the radial section 3a merges into a circumferential section 3c which runs essentially in the circumferential direction. A support 3d is also provided on the circumferential section 3c. The support 3d can, for example, be formed by a thickened portion. In the assembled state, the support 3d rests against the second section 2. The shape of the spring fingers 3 results in a spring effect in the X, Y and Z directions. The properties of the spring fingers can be changed by modifying the shape and / or the material.In addition, adjustable supports can be provided so that the spring stiffness can be specifically changed by moving the support.

[0033] In the Fig. 1 and Fig. In the embodiment shown in Figure 2, the spring fingers 3 are formed by cutouts in the first section 1. However, this is not mandatory; alternatively, the spring fingers 3 can also be formed on the second section 2 or as a separate component. For example, the spring fingers 3 can be formed from spring steel using a laser cutting process and then detachably connected to the first and / or second sections 1, 2. Likewise, a non-detachable connection, such as a welded connection, can also be provided.

[0034] The Fig. The measuring instrument holder shown in Figure 1 also comprises several sealing rings 4, which are provided between the first and second sections 1, 2. The sealing rings 4 seal the space between the first and second sections 1, 2 against dirt particles and, with a suitable choice of material, can also have a damping and / or spring effect. Plastics, in particular elastomers, can be used as the material for the sealing rings 4. Likewise, the sealing rings 4 can also be made of metal, for example copper, aluminum, or alloys of these metals. If a damping effect is intended, care should be taken to ensure that the material used has a higher inherent damping than the material used for the first and / or second sections 1, 2. In addition, Fig. 1 shows a screw-in ring by means of which the preload of the sealing rings 4 and thus the damping of the sealing rings 4 can be varied.

[0035] The damping can also be varied by the number, shape and material of the sealing rings. In addition to the Fig. 1, additional dampers, for example in the form of inserts, can be provided. The sealing rings 4 shown in Fig. 1 can be replaced by thicker or thinner sealing rings.

[0036] The cavity between the first and second sections 1, 2 can be filled with oil, grease, liquids, or powder, or mixtures thereof. The damping properties can be modified by filling the cavity. In addition to the filler material, the fill level also influences the damping properties. Accordingly, the cavity can be partially or completely filled.

[0037] In simple embodiments, the sealing rings 4 or dampers can also be omitted, since the inherent damping of the first and second sections, as well as the spring section, can be sufficient with the appropriate material selection. For example, the first section, the second section, and / or the spring section could be made of copper, aluminum, or plastic.

[0038] This design of the measuring instrument holder allows for a "soft" connection between the measuring instrument 6 and the machine tool, so that the measuring instrument 6 is decoupled from the machine tool to a certain extent. The lower the spring stiffness, i.e., the softer the spring fingers 3, the better the measuring instrument 6 can be decoupled from the vibrations of the machine tool. However, excessively low spring stiffness has the disadvantage that the measuring instrument 6 is not connected to the machine tool rigidly enough, thus reducing measurement accuracy.

[0039] Due to the elastic connection to the first section 1, the second section 2 and the measuring instrument 6 attached to it form an oscillating system whose natural frequency is determined by the spring stiffness of the spring fingers 3, the mass of the second section 2 and the measuring instrument 6, and the mass distribution. If damping is provided, this only results in a minimal reduction in the natural frequency, which can generally be neglected. This oscillating system is excited by the oscillations / vibrations of the machine tool, with the oscillations / vibrations of the machine tool representing the excitation frequencies.

[0040] The oscillating system enables passive isolation of the measuring instrument from the excitation vibrations. The natural frequency should be lower than the expected excitation frequencies, as effective vibration isolation generally only occurs above a certain frequency ratio.

[0041] While high damping prevents the system from oscillating, it also allows a large portion of the vibrations to be transmitted. Therefore, excessive damping can result in the measuring instrument not being able to be decoupled from the excitation vibrations to the desired extent.

[0042] During operation of a machine tool, the vibrations of the machine tool are transmitted to the first section 1, which is rigidly mounted, for example, in a tool turret. The spring section 3 between the first and second sections 1, 2 converts the vibrations of the first section 1 at least partially into a relative movement between the first and second sections 1, 2. During this relative movement, the second section 2 is pressed against the sealing rings, whereby the friction between the sealing rings and the first and / or second section and the inherent damping of the sealing rings slows down the relative movement and part of the vibration energy is converted into heat.

[0043] In the Fig. Figure 3 shows a second embodiment. The first section 31 has a so-called "VDI shank" and is thus adapted to a corresponding tool holder. This interface shape is defined in DIN 69880. It is clear that the illustrated embodiments can also have other shapes. Likewise, so-called hollow shank tapers, steep tapers, clamping shanks, or other common interfaces can also be provided.

[0044] In the second embodiment, the shaft 32a of the second section 32 is received inside the first section 31. The shaft 32a has a cross-sectional reduction 33 on its side facing the machine tool. This cross-sectional reduction 33 can be created, for example, by a recess. The second section 32 is connected to the first section 31 by screws 35. In addition, damping rings 34 are provided on the side of the shaft 32a facing the measuring instrument 6.

[0045] Due to the cross-sectional reduction 33, the shaft acts like a flexible rod, the spring stiffness of which can be adjusted by the shape of the cross-sectional reduction 33. If the spring stiffness of the shaft 32a corresponds to the desired spring stiffness even without a cross-sectional reduction, an additional cross-sectional reduction can be omitted.

[0046] Due to the shape of the shaft 32a, it is essentially rigid for vibrations in the Z orientation, so that corresponding vibrations are transmitted almost completely. For vibrations in the X and Y orientations, however, the shape of the shaft 32a at least partially isolates the measuring instrument 6 from vibrations.

[0047] In the same way as the cavity of the first embodiment, the cavity of the second embodiment can also be at least partially filled.

[0048] In Fig. A third embodiment is shown in Figure 4. The first section 41 can be detachably connected, for example by screws, to the second section 42. Slots 43 are provided in the second section 42, whereby the spring stiffness can be adjusted by the arrangement, depth, and number of the slots. Fig. 4, the cross-sectional weakenings created by the slots 43 largely overlap.

[0049] In addition to the described detachable connection of the first and second sections 1, 2, the shape of the spring section 43 also enables a one-piece design, i.e. a shape in which the first and second sections are made from one part and the slots 43 are introduced into the measuring instrument holder, for example by sawing or wire erosion.

[0050] In a simple variant of the third embodiment, sealing or damping rings between the first and second sections 41, 42 can also be dispensed with.

[0051] Examples include Fig. 4 holes 44 are shown, where, for example, a connection with Fig. 7 can be attached. Furthermore, the bores 44 can also be provided for connecting the first and second sections 41, 42. If, for example, a screw connection is provided, some of the screws can additionally be provided for adjusting the vibration gap of the spring section 43 and thus the elasticity of the spring section 43.

[0052] The Fig. 5 shows a fourth embodiment. In this embodiment, an intermediate piece 53 is provided between the first section 51 and the second section 52. The intermediate piece 53 can have the form of a bellows, which is made of plastic or metal, for example. To fasten the intermediate piece 53 to the first section 51, a clamping ring 55 can be provided, which clamps the intermediate piece 53 against the first section 51. A thread can be provided on the first section 51 to firmly connect the clamping ring 55 to the first section 51. The second section 53 can either be screwed directly to the intermediate piece 53 or with screws, as in Fig. 5, are connected to the intermediate piece.

[0053] In the Fig. In the fifth embodiment shown in Figure 6, the second section 62 is slidably received in the first section 61. A pressure chamber 64 is provided between the first and second sections 61, 62. An opening 64a is provided in the first section 61 so that the pressure chamber 64 can be connected to a pressure source, for example, a compressed air connection or a cooling lubricant connection, of the machine tool. Fig. 6, the pressure source to be connected is indicated by the arrow labeled P. The pressure chamber 64 is preloaded by a return spring (not shown). The pressure present in the pressure chamber 64 acts against a first surface 65 of the second section 62 and thereby counteracts the preload of the return spring. Thus, in the fifth embodiment, the first and second sections 61, 62 form a cylinder / piston arrangement. In addition, sealing rings 63 are provided to seal the pressure chamber 64. Plastics, in particular elastomers, can be used as the material for the sealing rings 63. The sealing rings 63 form a soft, elastic connection between the first section 61 and the second section 62.

[0054] The second section further comprises a first face toothing 66 and a second face toothing 67 attached to a cover. The cover is rigidly attached to the first section 61 by a clamping ring 68.

[0055] Due to the cylinder / piston arrangement, the second section 62 can be displaced relative to the first section 61, i.e. from a Fig. 6 into a measuring position. The return spring (not shown) is provided to preload the second section 62 in the rest position. An elastomer ring can also be provided to preload the second section 62.

[0056] In the rest position, the second section 62 is connected to the first section 61 by the elastic sealing rings 63. Accordingly, there is a soft, elastic connection between the first and second sections 61, 62. As a result, the second section 62 is at least partially vibration-isolated from the first section 61.

[0057] In the measuring position, the second section 62 is displaced to the left by pressure applied to the first surface 64. In this position, the first and second face gears 66, 67 mesh and create a rigid connection between the first and second sections 61, 62. As a result, the second section is rigidly connected to the first section 61, 62, so that the measuring accuracy of the measuring instrument 6 is not impaired.

[0058] Since the cylinder / piston assembly is preloaded in the rest position, the measuring instrument 6 attached to the second section 62 is elastically connected to the tool turret when held ready in a tool turret. Accordingly, the measuring instrument 6 is protected from the oscillations / vibrations generated by workpiece machining.

[0059] When a workpiece is to be measured, the measuring instrument holder held ready in the tool turret is conveyed to the working position of the machine tool and picked up there. The pressure chamber 64 can be automatically connected to a pressure source, for example a coolant connection of the machine tool. A control command from the machine tool's control system can open the coolant connection of the machine tool, allowing coolant to flow into the pressure chamber 64. The pressure of the coolant causes the second section 62 to be displaced to the left until the first and second face gears 66, 67 engage. Since the intermeshing face gears form a rigid connection between the first and second sections, a high level of measurement accuracy can be achieved. The desired parameters can then be recorded in the measuring position.Once the desired parameters have been recorded, the control system can close the coolant connection, allowing the pressure in the pressure chamber 64 to decrease. The return spring pushes the second section 62 back to its rest position. The measuring instrument holder can then be removed from the working position and stored in the tool turret until the next use.

[0060] In Fig. 7 shows a measuring instrument holder with an additional mass 75 attached to it. In the Fig. In the embodiment shown in Figure 7, the additional mass 75 is attached to the second section 72. The additional mass 75 is connected to the second section 72 and to the measuring instrument 6 via elastic and / or damping intermediate rings 74. Compared to the second section 72, the intermediate rings can be made of a material that has a low modulus of elasticity and high inherent damping. In addition to a resilient and / or damping connection of the additional mass 75, a rigid connection between the additional mass 75 and the second section 72 can also be provided. Accordingly, the additional mass 75 can also be attached directly, i.e., without intermediate rings 74, to the second section 72 and / or the measuring instrument 6.

[0061] Additionally, bolts can be provided, which, for example, are inserted into the Fig. 4. These bolts can be provided to connect the second section 72, the intermediate ring 74, and the additional mass 75 to one another. The bolts can be made of an elastic plastic. Furthermore, the bolts and the intermediate ring 74 can be molded as a single part.

[0062] The additional mass can be used to reduce the natural frequency of the second section 72 and of the measuring instrument 6 to be attached thereto in order to change the frequency ratio between the excitation frequency and the natural frequency in the desired manner.

[0063] In addition or as an alternative to the additional mass, a vibration absorber can be provided, as shown in Fig. 8. A vibration absorber comprises a mass that is connected to an oscillating mass via a spring element and a damper. In a simple design, the spring element can be made of an elastic plastic that also has damping properties. Unlike an additional mass, a vibration absorber does not change the natural frequency of the second section and the measuring instrument attached to it. Rather, the vibration absorber extracts energy from the oscillating mass. In particular, the appropriate selection of mass, spring stiffness, damping, and position of the vibration absorber can prevent or at least reduce oscillation at the natural frequency.

[0064] In the Fig.In the embodiment shown in Figure 8, the vibration absorber comprises an annular mass 85 that is connected to the measuring instrument via an elastomer ring 84, for example, a rubber ring. The vibration absorber should be mounted at the location where the greatest movement / deflection is expected. Accordingly, the vibration absorber can also be mounted at other positions, depending on the shape, mass, and mass distribution of the second section and the measuring instrument. The vibration absorber can also be mounted on the first section 81.

[0065] Although the details of the methods and the device explained above are presented in context, it should be noted that they are independent of one another and can also be freely combined with one another, at least to the extent that individual patent claims are made relating to them.

Claims

[1] Measuring instrument holder for holding a measuring instrument (6) on a machine tool, with a first section (1, 31, 41, 51, 61, 71, 81) to be attached to a tool holder of the machine tool; a second section (2, 32, 42, 52, 62, 72, 82) receiving the measuring instrument (6); wherein the first section (1, 31, 41, 51, 61, 71, 81) and the second section (2, 32, 42, 52, 62, 72, 82) are connected to one another by a spring section (3, 33, 43, 53, 63) such that the second section (2, 32, 42, 52, 62, 72, 82) and the measuring instrument (6) to be attached to the second section are at least partially vibration-isolated from the first section (1, 31, 41, 51, 61, 71, 81) to be attached to the machine tool in at least one orientation, characterized bythat the first section (1, 31, 41, 51, 61, 71, 81) is provided for receiving on a standardized tool holder of a machine tool and has a shape which is adapted for fastening to a hollow shank taper, steep taper interface, or has the shape of a VDI shank. [2] Measuring instrument holder according to the preceding claim; wherein the first section (1, 31, 41, 51, 61, 71, 81) and the second section (2, 32, 42, 52, 62, 72, 82) are formed from one part or from two separate parts. [3] Measuring instrument holder according to one of the preceding claims, wherein the first section (1, 31, 41, 51, 61, 71, 81) and the second section (2, 32, 42, 52, 62, 72, 82) are further connected to one another by at least one damper (4, 34). [4] Measuring instrument holder according to claim 3, wherein the at least one damper (3, 34) comprises a partially or completely filled cavity. [5] Measuring instrument holder according to one of the preceding claims, wherein a vibration damper (84, 85) is provided which reduces vibrations on the measuring instrument (6) to be attached and / or an additional mass (75) is provided which reduces the natural frequency of the second section (2, 32, 42, 52, 62, 72, 82) and of the measuring instrument (6) to be attached to the second section. [6] Measuring instrument holder according to one of the preceding claims, with a rest position and a measuring position, wherein in the rest position the second section (2, 32, 42, 52, 62, 72, 82) is at least partially vibration-insulated and in the measuring position there is a spring-stiff connection between the first section (1, 31, 41, 51, 61, 71, 81) and the second section (2, 32, 42, 52, 62, 72, 82). [7] Measuring instrument holder according to claim 6, wherein an electric, hydraulic or pneumatic actuator is provided to change from the rest position to the measuring position. [8] Measuring instrument holder according to one of the preceding claims, wherein the spring section (3, 33, 43, 53, 63) is formed by at least one recess on the first and / or second section (1, 2, 31, 32, 41, 42, 51, 52, 61, 62, 71, 72, 81, 82) and / or the spring section (3, 33, 43, 53, 63) is formed by a separate spring element. [9] Measuring instrument holder according to one of the preceding claims, wherein the spring stiffness and / or at least one vibration gap of the spring section (3, 33, 43, 53, 63) are variable. [10] Method for measuring a workpiece in a machine tool with: - Providing a measuring instrument in a tool turret of the machine tool, wherein the measuring instrument is accommodated in a measuring instrument holder; - conveying the measuring instrument holder to a working position of the machine tool; - Controlling the measuring instrument holder so that it changes from a rest position to a measuring position; - Recording parameters; - Moving the measuring instrument holder away from the working position.

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