HK1135940B - Self-powered coordinate probe - Google Patents

Description

Self-powered coordinate probe

Technical Field

The present invention relates to a measurement probe for use with an industrial machine tool or coordinate measuring machine, particularly suitable for use in a Computer Numerical Control (CNC) machine. The invention relates in particular to a self-powered tool for making measurements on a workpiece.

Background

Machine tools capable of automatically replacing different types of tools in order to perform various machining or measuring operations on a workpiece are well known and widely used in the art. The modular tool can be simply and removably fixed to the machine tool, so that it is not necessary to equip each specific operation with a specific machine tool.

Whenever such tools have circuitry in them, it is necessary to supply the circuitry, or at least to provide some form of detachable electrical connection between the tool holders beforehand.

Modular probe heads are typically mounted on a standard tool holder, such as a morse taper shank, which is then removably attached to a spindle (spindle) or rotary spindle machine tool for performing a wide variety of measurements and dimensional controls. This is typically done prior to performing, for example, milling, boring, or other machining operations on the workpiece. Such modular probe heads are used, for example, to ensure correct positioning of a workpiece before starting a machining operation, or to check whether the dimensions of the workpiece are within acceptable ranges.

Powering such probe heads is often problematic in such situations, as the handle associated with the probe housing typically does not have any power or electrical connections. This is almost always the case when it is not possible to connect the probe to any electrical line when it is connected to the rotating shaft, and it must be considered that the power supply is completely self-powered.

In order to perform measurement operations, it is common to use an internal battery to power the probe head, and also to transmit information to the machine tool control unit. The limited service life of the battery makes it necessary to regularly charge the battery and/or to manually replace the battery, but such requirements are also demanding and time consuming.

With generators, various systems that convert mechanical energy into electrical energy have been proposed as alternatives to batteries to address this power supply problem.

US5564872 describes a wireless probe using an in-line turbine of incoming fluid compressed air as an electromechanical transducer. Similarly, US4716657 and US2007006473 describe a measuring probe provided with a turbine fed with a compressed fluid to generate electrical energy.

These solutions require a sealed tube to transport the flowing fluid, and also require a precise sealing of the tool holder with the probe in order to avoid fluid leakage or pressure loss when installing the probe. These are not easy to implement and require special design of the tool holder. When possible, in most cases the connection between the probe and the fluid circuit (e.g. cutting fluid line) must be made manually and separately.

JP3223602 discloses another solution for generating electrical energy, where the rotating shaft of the machine tool directly drives the generator in the probe while rotating, while the housing of the probe is fixed to a non-rotating element on the machine tool head. This requires a second mechanical connection in addition to the standard taper shank and does not allow for quick and easy tool changes when transferred from one mechanical operation to another.

Accordingly, there is a need to provide a self-generating system of electrical energy for a modular probe head having electrical circuitry that is not limited by the above.

Disclosure of Invention

The above object is achieved according to the present invention by a contact probe and a method for generating electrical energy having the features of the independent claims. Preferred embodiments are detailed in the dependent claims. In particular, the above object is achieved by a coordinate probe for a machine tool comprising: a support element connected to a rotating shaft of the machine tool; a coordinate sensor for measuring coordinates of points on a surface of the workpiece, the coordinate sensor employing an electrical or electronic circuit; a generator for supplying power to said electrical or electronic circuit, characterised by a drive member at least partially freely rotatable about an axis relative to a stator of said generator, said generator being operatively arranged to generate electrical energy in dependence on the relative difference in angular velocity between said drive member and said stator.

The above solution improves the efficiency of the overall system, above all in terms of power consumption. This converted energy, which is already generated by the machine tool and can be stored and reused in another form, does not really require the use of any additional energy source; furthermore, since there is no problem of electrical independence on the machine side, the mechanical energy transferred to the probe is theoretically unlimited. The use of a flywheel as the primary energy source allows for optimal conversion of the mechanical energy present in the system into electrical energy for production.

Another advantage of the above solution is that it provides a universal solution for modular contact probes with independent power supplies, suitable for various operating purposes. No special design or adjustment means are required to connect it to the machine tool, since the kinetic energy generated in an independent manner within the attached probe housing is used; this solution can use any conventional support means.

Other advantages of the above solution are the ease and simplicity of use and the almost maintenance-free operation.

Drawings

The invention will be better understood by means of the description of embodiments in conjunction with the accompanying drawings, in which:

fig. 1 shows a cross-sectional view of a probe according to a preferred embodiment of the present invention.

Fig. 2 shows a perspective view of a probe according to a preferred embodiment of the present invention.

Fig. 3 shows a top view of a power generating unit according to a preferred embodiment of the invention.

Fig. 4 shows a power generation unit according to another embodiment of the present invention.

Fig. 5 and 6 show another embodiment of the present invention.

Fig. 7 shows another embodiment of the present invention.

Detailed Description

Fig. 1 shows a cross-sectional view of a probe 11 according to a preferred embodiment and an application example of the invention. For simplicity of illustration, it is assumed that the probe 11 is applied to a conventional CNC milling machine 12 having 3 linear axes XYZ and one axis of rotation 15, which should not be construed as limiting the invention, the probe being applicable to various models of machine 12.

In this example, probe 11 is removably secured to a spindle 15 of machine tool 12 by means of a holder comprising a standard cone 13 compatible in use with said machine tool. For simplicity, the cone is shown in the drawings as being integral with the probe. However, it must be understood that the probes of the present invention are not limited by this particular manner of attachment. The taper shank is typically part of a separable tool holder to allow interoperability with different machine tools. The spindle 15 is driven to rotate about the axis of rotation 14, also defined as the direction in which the probe is removed and attached to the spindle 15.

The above-described clamping mechanism for securing a work tool to the machine tool 12 has been widely used; preferably, therefore, shank 13 of probe 11 is interoperable with conventional machine tool 12 without any particular design. By appropriate programming of the XYZ axes of machine tool 12, the fastening system of the present invention not only allows probe 11 to move anywhere in the three-dimensional measurement space, but also drives probe 11 to rotate with machine tool spindle 15; any system capable of removably attaching such a probe having a rotary drive feature is suitable for use with the present invention.

At the opposite end of the shank 13, a housing 27 supports a surface sensing and/or measuring device, such as the touch trigger probe 11, which includes an elongate stylus 26 connected to the detection circuitry 22, preferably itself connectable to the telemetry system unit 24 for transmitting measurement results to a remote control unit (not shown) and/or receiving instructions for the measurement process. If the extended contact pins 26 are misaligned, an electrical signal is triggered as soon as the electrical contacts 23 of the detection circuit 22 are opened. The invention is not limited to this particular type of probe and can also be used with analogue probes and non-contact probes, such as laser probes, to generate measurements of the coordinates of points on the surface of the workpiece when the measurements are taken.

The measured coordinate values are suitably encoded and transmitted to the telemetry system unit 24 for wireless data transmission. The transmission of data may be via optical or radio frequency transmission, e.g. via infrared or via a radio link 34, as shown using e.g. bluetooth technology or any wireless technology for short distance transmission. A low power transmission system is preferred. Other wireless data transmission techniques, such as WLAN, are also envisioned where higher bandwidth and/or longer distance is required. Preferably, the I/O interface of the telemetry system 24 may be periodically turned off for power conservation, or a state where a default value is set to idle and ready for transmission only for a predetermined period of time. Other wireless transmission technologies such as GPRS or EDGE may also be used; the list of wireless technologies listed above is not exhaustive.

Power for the contact detection circuit 22 and/or the telemetry unit 24 is supplied primarily by the generator 16. According to the preferred embodiment shown in fig. 1, the rotor 17 of the generator 16 is arranged below the drive element 28, which according to this embodiment is a flywheel rotatably connected to the probe. Sufficient moment of inertia can be provided to maintain its angular velocity independent of the rotation of the probe housing 26. The flywheel 28 may be, for example, an add-on module (add-on module) connected to the rotating shaft of the generator 16, thus allowing for improved scalability of the existing generator module 16.

The rotor 17 carries permanent magnets 19 which, when there is relative rotation between the stator 18 and the rotor 17, induce currents in the windings 20 of the stator 18.

The probe 11 of the present invention is mounted on the spindle of the machine tool and thus can be rotated at high speed. In various embodiments of the present invention, the stator and rotor may rotate simultaneously, while in other cases the stator of the generator may spin when the rotor is at rest. The terms "stator" and "rotor" should not be construed as absolutely stationary or absolutely rotating in any particular frame of reference, but rather as relative. An example of one power generation cycle will be described below. The spindle 15 of the CNC machine is first actuated to rotate with the probe housing 27. The flywheel 28 does not follow the housing 26 due to its large moment of inertia. If the system is considered in a reference frame fixed to the probe housing, the generator 16 "sees" that the rotor 17 and flywheel 28 rotate relative to each other in opposite directions.

The flywheel, which is preferably mounted on a low coefficient of friction bearing, will continue to spin (relative to the probe housing 27) for a considerable period of time as long as the shaft continues to rotate. The permanent magnets 19 of the rotor still produce an induced electromotive force on the windings 20 of the stator. If current is allowed to circulate in the windings, generating net positive power, electric braking will ensue, and the flywheel reaches the same angular velocity as the housing (in a reference frame fixed to the probe housing), its kinetic energy is converted into electric energy.

Once the flywheel 28 has rotated at a speed equal to the speed of the housing, the shaft 15 and the housing 27 of the probe stop rotating. The flywheel 28 now appears to be self-transmitting with respect to the stator of the generator 16 in the direction of the initial rotation of the shaft. The kinetic energy of the flywheel 28 can be converted into electrical energy again until the flywheel 28 again reaches the angular velocity of the housing. The above power generation cycle may be repeated as many times as necessary.

In the above embodiment, as long as there is angular acceleration or angular deceleration of the shaft in the transient phase after the sudden change in the speed of the shaft, the inertia of the flywheel 28 can be used to generate electric energy. If the shaft rotates at a constant angular velocity, the flywheel also rotates at the same velocity, and no energy is generated.

It is also possible to reverse the shaft according to another variable instead of simply stopping the rotation of the shaft, thereby doubling the speed of rotation of the flywheel relative to the stator. The inversion may be repeated periodically to continue energy production. In order to increase the moment of inertia of the flywheel 28, i.e., to allow more kinetic energy to be stored at a given number of revolutions per minute (rpm), the flywheel 28 should be made of as heavy a material as possible, such as a heavy metal, e.g., iron, platinum, tungsten, lead, etc. On the other hand, in order to reduce the size of the generator 16 while increasing its output, the magnet 19 is preferably a rare earth permanent magnet with a high magnetic energy product, such as a samarium-cobalt magnet or an NIB (neodymium-iron-boron) magnet.

The power generating unit 16 is capable of powering all of the circuits 22, 24 mentioned above and more generally a portion of the electrical or electronic circuitry of the telemetry system unit and/or the I/O wireless transmission unit 24 of the coordinate probe 11. The power supply is generated whenever the relative rotational speed between the flywheel 28 and the probe housing 27 is not equal to zero, i.e. when the rotor 17 is actually rotating relative to the stator 18. This can also occur, for example, when the housing 27 of the probe is accelerating or decelerating.

Since the inertial effect is used to provide relative rotation of the rotor 17 and stator 18, no air sealing mechanism is required between the machine tool and the probe, as opposed to the solutions typically provided by prior art pneumatic systems. Thus, probe 11 can be installed and replaced more easily and quickly.

According to the preferred embodiment shown in fig. 1, the probe further comprises another circuit, such as a voltage converter 25, for amplifying the voltage generated by the generator 16 and boosting the voltage to a voltage level at which the other circuits 22, 24 are adapted to operate. Suitable voltage ranges for circuit operation are typically at least about 3-4 volts. The voltage converter may be a solid state voltage multiplier or any solid state AC/DC converter capable of making the output voltage higher than the input voltage. Thus, a higher dc voltage than the voltage generated by the generator 16 can be generated. A converter 25 is preferably installed between the output of the generator 16 and the input of the telemetry system 24 in order to provide the greater voltages necessary for the transmit and receive phases. The step of converting the output of the generator 16 to dc voltage produces a higher dc voltage whenever necessary, as required by any electrical or electronic circuit 22, 24.

A probe head 11 without any energy storage mechanism is conceivable. But in this case energy needs to be generated when performing measurement operations and/or data transmission operations, which is a strong limiting factor. An energy storage unit 32 is required within probe 11 for storing energy provided by generator 16. The energy generation cycle need only be performed at intervals and preferably not during actual measurements.

The energy storage unit 32 may serve as the primary source of energy within the probe for powering the circuits 22, 24 only when the generator 16 is off; it may also be used as an auxiliary energy source when generator 16 is operated and/or when probe 11 is used for measurement purposes, or as a buffer to store excess energy formed by generator 15. Such a storage unit 32 can therefore be used alternatively or in combination with the generator 16, which provides greater flexibility in operation. For example to allow measurements to be performed within an acceptable measurement time without requiring any rotation of any part of the probe, more generally to activate the motor only when absolutely necessary.

According to a preferred embodiment of the present invention, the energy storage unit 32 stores the generated electric energy, and is, for example, a rechargeable battery or a buffer capacitor. Electrochemical Double Layer Capacitors (EDLCs) having excellent memory characteristics may also be used.

To minimize the maintenance requirement of providing power to probe 11, storage device 32 may be automatically charged in advance whenever a power shortage is detected. To this end, an energy measurement unit 33 may be connected to the energy storage device 32 so as to indicate the amount of stored power present at any given time. Preferably, such an energy measuring unit 33 is also connected to the telemetry system 24 and is able to trigger the transmission of an alarm signal to a control unit (not shown in the figures) as soon as a minimum power level is reached. Upon receipt of such an alarm signal, the control unit sets the machine spindle 15 to rotate about the axis of rotation 14 to switch on the generator 16, so that sufficient energy can be provided and stored in the storage device 32. The steps of driving the rotating shaft 14 of the machine tool 12 and converting kinetic energy into electrical energy may be repeated multiple times to achieve a desired energy level.

Fig. 2 shows a perspective view of probe 11 according to another preferred embodiment, showing the mechanism of internal generator 16. The inertia mass 28, which is integral with the rotor 17 below the shank 13 in the housing 27, and the hole adapted to receive the permanent magnet 19 can be seen in cross section. Opposite the rotor 17 is a stator 18 and windings 20 embedded in the stator.

Under the stator 18 is mounted a buffer capacitor, or any other known form of energy storage unit 32, for storing the generated electrical energy. The buffer capacitor 32 is connected to a circuit board 35 on which various electronic components are mounted, including, for example, the CPU36, the contact detection circuit 22, and components in the telemetry system unit 24 (not shown). Other components than the CPU are not visible because they are preferably mounted underneath the circuitry within the housing 21, which provides the necessary space for their placement. The wireless transmission portion of the telemetry system 24, for example consisting of an antenna or infrared port, is preferably mounted on the outer surface of the housing 21 to minimize signal attenuation. The wireless transmission section is visible at one side of the housing 21.

The CPU36 is preferably used to process signals received by the detection circuitry 22 as long as the probe stylus 26 is deflected relative to its mounting axis. In fig. 2, the mounting axis coincides with the rotation axis 14 of the probe 11 and the machine tool 12. The signal is then passed to the telemetry system unit 24 for transmission to the remote control unit. However, as already mentioned herein before, the CPU36 may also serve as a data transmission and reception interface. After analysing the instructions received via the radio link 34, the generator 16 is actuated to cause the probe 11 to perform a measurement procedure. In the preferred embodiment comprising an energy measuring unit, the CPU is also preferably connected to an energy measuring unit 33. In this case, the CPU36 processes the sending of the alarm signal whenever the power level is too low and transmits the signal to a remote control unit (not shown in the figure) via the radio link 34. The CPU36 is also responsible for determining which power consuming operations should be run on stored energy and which operations require real-time supply of electrical energy by the generator 16.

Fig. 3 shows a top view of a generator 16 comprising a series of magnets 19 embedded on a rotor 17. The poles of each successive series of magnets 19 are arranged in opposite directions (N, S representing north and south poles respectively) so that the induced magnetic flux in the windings 20 is alternating. The generator 16 in the figure comprises a one-way clutch 29 for transmitting the rotation of the support element 13 in one direction only to the flywheel 28 of the rotor 18. In this example, the clutch 29 is based on the cooperation of undulating teeth 30 on the outer periphery of the rotor 18 with a pawl 31 fixed to the probe housing 27. It will be obvious that this embodiment is given by way of example only and that many other overrunning or freewheel clutches are applicable to the present invention. When the spindle 15 of the machine tool 12 is free to be driven, the clutch may allow the flywheel 28 of the rotor 17 to be driven at the same speed as the housing 27, i.e. to rotate clockwise as shown in the embodiment, and to disengage the flywheel 28 when the machine tool spindle 14 is driven in a direction opposite to the first direction. Once the shaft 15 stops rotating, the deceleration of the probe housing 27 will be substantially faster than the deceleration of the rotor 18, the rotor 18 will continue to spin due to the moment of inertia, and the flywheel 28 will disengage. The resulting relative rotational speed of the rotor 17 can be used to generate electric current as previously described.

The inclusion of the one-way clutch 29 shortens the power generation cycle because the flywheel 28 can instantaneously accelerate to the same rpm as the probe. The generator 16 only needs to be operated in one rotational direction, which simplifies the construction and the accompanying circuitry.

In order to maximize the energy generated by the generator 16, the friction losses in the rotation of the rotor 17 should be as low as possible. For this purpose, rollers, needles or ball bearings (not shown in the figures) may be pre-mounted on the shaft of the rotor 17 and any suitable lubricating material used on the pawls 31 and teeth 30 of the blocking mechanism (blocking mechanism).

As in the embodiment shown in fig. 3, the rotor 17 may also be integrated with a flywheel 28 carrying magnets 19 for generating an induced current in the windings of the stator. Fig. 4 shows an alternative variant in which the flywheel 28 and the probe housing 27 are formed in one piece, whereby the magnet 19 will be fixed to this piece or incorporated on the inner surface of the housing 27. Reference numerals 17, 27 and 28 are therefore incorporated on the probe housing. In this embodiment, the windings of the stator 18 are preferably provided with minimal gaps to provide sufficient induced current to all of the circularly distributed coils. A collar ring comprising annular multi-pole magnets may be provided inside the housing 27 in place of those plurality of magnets 19.

In this embodiment of the invention, as shown in figure 4, the strut 13 is preferably directly connected to the stator 18 and drives it to rotate about the shaft 14, while the bearing joint 37, such as a ball bearing, keeps the housing from following the spinning motion.

The design method of probe 11 disclosed in the present invention provides a self-powered mechanical structure and an operation that requires little maintenance. Probe 11 according to the present invention should be fully self-sufficient in energy to operate such that it is never necessary to replace the batteries used to increase the overall utility of the system. Generating the current on demand will have the greatest flexibility whenever it is necessary to intermittently include an external predetermined time period, and also the greatest flexibility with any possible circuit operation. Self-powered mechanical structures are more energy efficient than commonly available solutions because no additional systems, such as pneumatic systems, are required to provide kinetic energy for energy conversion.

According to another embodiment of the invention, as shown in FIG. 5, the drive element 28 is part of the probe housing, is rotatably connected to the probe body, and provides protruding blades 121 to maximize its aerodynamic resistance. Thus when the shaft 13 starts to rotate, the drive element will rotate at a lower speed than the same speed as the shaft. This difference in angular velocity causes the winding 20 to generate an electrical quantity. It will be seen that this embodiment is identical in principle to the previous embodiment, namely by using the difference in rotational speed between the probe drive element and the stator element, and hence between the generator stator and rotor. The difference with respect to the previous embodiment is that the difference in speed is not caused by inertia, but by the aerodynamic braking of the blades 121. Advantageously, the speed difference and the power production can be maintained indefinitely or when required, whereas in the previous embodiment the energy production was limited during the acceleration and deceleration phases, so the variables based on inertia must be intermittent. In an ideal situation, the electrical energy generated in this embodiment is equal to the mechanical energy dissipated in the aerodynamic braking device.

It is clear that fig. 5 only provides an example of the profile and configuration of the blades and that other forms of aerodynamic braking devices can be substituted without departing from the scope of the invention. A preferred variation is to use a self-expanding blade which folds up close to the probe body in a tight configuration when the shaft is not rotating and extends from the probe body in an extended configuration for maximum resistance. Centrifugal force, aerodynamic force, or any other method or combination thereof may drive the blades to deploy.

According to another variant of the invention shown in fig. 6, the drive element 28 is in a braking condition when the CNC machine is activated to move the probe to a predetermined braking position. In the example shown, the drive member 28 is part of a probe housing, rotatably connected to the probe body, and a brake member 130 mounted on the machine table contacts the drive member 28 to resist its movement. If in this position the shaft is arranged to rotate, the magnet-carrying drive element 28 will not follow the rotation, and electrical energy is generated by the windings 20.

With respect to the shape and position of the braking element 130, it is clear that the invention encompasses many variants and alternatives, the shape of the hands shown in fig. 6 being given as an example only. The position of the braking element 130 is not fixed. The position of the braking element 130 is not fixed. In a preferred variant, the braking element 130 is incorporated in a tool magazine from which the CNC machine can automatically pick up the tools and the probe.

To improve the braking effect, a number of optional features may also be added in this variant of the invention. For example, the drive element 28 and/or the fixed pointer 130 may have a rubber-like surface or a surface of a material having a high coefficient of friction. Additionally or alternatively, the drive member 28 may have a female portion and a male portion that mate with the pointer 130 as shown in FIG. 6.

According to the embodiment shown in fig. 7, the drive element 28 is not connected to the probe body, but is fixed in a predetermined position of the reference surface of the machine tool, for example in a tool magazine. In this variant, the probe has windings 20 mounted thereon, and the drive element 68 has a plurality of permanent magnets 19. To generate electrical power, the CNC machine is driven to insert the probe into the drive element, or at least into a magnetic relationship with the drive element, and then the spindle is set to rotate for a sufficient time to store the required energy in the battery. An advantage of this embodiment is that the probe is more lightweight.

The positioning accuracy of the CNC or coordinate machine on which the probe is mounted is generally sufficient to ensure that the probe is accurately inserted into the drive element 68 and is free to rotate without any contact between the two elements. The insertion of the probe into the drive element should be carefully programmed to avoid unnecessary contact.

In order to make the insertion of the probe easier, it is advantageous to provide the drive element with one or more rotatable elements, on which the probe can be positioned. In this case, the drive element preferably includes a resilient mount which compensates for misalignment of the probe. In fact, as is the case in the embodiment of fig. 6, the drive element should advantageously be incorporated into the tool magazine or embedded in the tool holder. This advantageous configuration allows the required energy to be generated right at the start of the measurement.

Embodiments of the invention relate to a probe connectable to a machine tool, comprising a generator 16 for supplying electrical power to an electrical or electronic circuit 22, and a drive element 28 capable of relative rotation with respect to a stator of the generator. The axis of rotation of the drive element is preferably the axis of symmetry of the probe. The drive element is not connected to any external energy source and is caused to rotate simply by triggering the movement of the machine tool's rotating shaft.

Advantageously, the driving element of the invention is not directly connected to any moving element of the machine tool, but can be mounted rotatably on the probe itself, or fixed on a reference table of the machine tool. Importantly, the probe of the present invention does not require additional attachment means to be attached to the machine tool other than to the rotary spindle, which can be implemented with a conventional tool holder having a standard taper shank. The probe of the present invention is thus fully compatible with standard probes and can be installed and used in standard tool holders without any modification. The self-powering function of the probe can be activated simply by sending a suitable rotation command to the spindle of the machine tool.

According to various embodiments of the invention, the relative rotation of the drive elements is obtained by dissipative braking of the drive elements. In other variants, the relative rotation of the drive element is simply brought about in a fixed position on the machine table or in a support device like a tool holder or tool magazine.

According to different variants and embodiments of the invention, the energy can be generated at any position, or only when the probe is moved to a specific position with respect to the same brake or drive element.

List of reference numerals

11 Probe

12 machine tool

13 supporting element (taper handle)

14 rotating shaft of machine tool

15 rotating shaft of machine tool

16 power generation unit

17 Generator rotor

18 generator stator

19 magnet

20 windings

21 circuit shell

22 contact detection circuit

23 electric contact

24 telemetry system unit

25 voltage conversion circuit

26 probe stylus

27 Probe case

28 flywheel, drive element

29 one-way locking device

30 wave-shaped teeth

31 ratchet pawl

32 energy storage unit

33 energy measuring unit

34 radio transmission link

35 circuit board

36 CPU

37 bearing joint

121 aerodynamic brake blade

130 brake pointer

135 concave part

Claims (19)

1. A coordinate probe for a machine tool comprising:

a support element connected to a rotating shaft of the machine tool;

a coordinate sensor for measuring coordinates of points on a surface of the workpiece, the coordinate sensor employing an electrical or electronic circuit;

a generator that supplies the electrical or electronic circuit,

it is characterized in that the preparation method is characterized in that,

a flywheel at least partially free to rotate about an axis relative to a stator of the generator, and a one-way clutch for transmitting rotation of the support element to the flywheel when the machine tool rotational axis is driven in a first direction, the one-way clutch disengaging the flywheel when the machine tool rotational axis is driven in a direction opposite to the first direction, the generator being operatively arranged to generate electrical energy in dependence on the relative difference in angular velocity between the flywheel and the stator.

2. The coordinate probe of claim 1, wherein the stator comprises windings.

3. The coordinate probe of claim 1, wherein the flywheel is configured to rotate relative to the generator stator by activating a machine tool rotation axis.

4. The coordinate probe of claim 1 wherein the coordinate probe does not require additional connecting means to connect to a machine tool other than connecting to a rotating shaft of the machine tool to generate electrical power.

5. The coordinate probe of claim 1, wherein the coordinate sensor is a stylus-type probe and the electrical or electronic circuit is a stylus-to-workpiece contact detection circuit.

6. The coordinate probe of claim 1, wherein the electrical or electronic circuit is part of a telemetry system unit and/or part of an input/output wireless transmission unit of the coordinate probe.

7. The coordinate probe of claim 1, further comprising an energy storage device for storing electrical energy provided by the power generation unit.

8. The coordinate probe of claim 7, further comprising an energy measurement unit coupled to the energy storage device.

9. The coordinate probe of claim 1, wherein the flywheel is integrally formed with a rotor of the generator and is loaded with permanent or rare earth or neodymium iron boron magnets.

10. The coordinate probe of claim 1, wherein the probe housing functions as a flywheel.

11. The coordinate probe of claim 1 further comprising an ac/dc voltage conversion circuit for generating a dc voltage higher than a voltage generated by the generator.

12. The coordinate probe of claim 1, wherein the flywheel includes an aerodynamic brake.

13. The coordinate probe of claim 1, wherein the flywheel is placed at a fixed position in a machine tool reference frame.

14. The coordinate probe of claim 1 wherein the flywheel is driven by a tool holder, the tool holder acting on the flywheel as a fixed position.

15. A method of generating electrical power using a coordinate probe removably connected to a machine tool, comprising the steps of:

connecting the support element of the probe to the rotation axis of the machine tool;

rotating the rotating shaft of the machine tool, thereby causing relative rotation of the flywheel in the coordinate probe with respect to the driving element of the generator in the coordinate probe; the coordinate probe further comprising a one-way clutch for transmitting rotation of the support element to the flywheel when the rotational axis of the machine tool is driven in a first direction, the one-way clutch disengaging the flywheel when the rotational axis of the machine tool is driven in a direction opposite to the first direction,

the kinetic energy of the flywheel is converted into electric energy through the generator.

16. A method according to claim 15, comprising the step of accelerating and/or decelerating the rotational axis of the machine tool, wherein the generator generates electrical energy whenever the relative rotational speed between the drive element and the flywheel of the probe is not equal to zero.

17. The method of claim 15, wherein energy is generated on demand.

18. The method of claim 15, further comprising the step of measuring the energy stored in an energy storage unit of the coordinate probe, wherein the steps of driving the machine tool rotation axis and converting kinetic energy into electrical energy are repeated until the stored energy reaches a minimum set level.

19. The method of claim 15, further comprising the step of converting the output of the generator to a dc voltage, wherein the dc voltage is higher than the voltage at which the generator outputs.