JP2005331450A - Micro-displacement controller, and device and method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro-displacement controller capable of obtaining precisely a micro displacement, using an expansion controller for a supermagnetostrictive element, by constituting the expansion controller for the supermagnetostrictive element capable of controlling extremely precisely an expansion amount and the displacement accompanied thereto, without providing basically the supermagnetostrictive element in a coil. <P>SOLUTION: In this micro-displacement controller, the objective micro displacement is attained using the expansion controller for the supermagnetostrictive element constituted to output a displacement in a free end, with expansion and contraction of the supermagnetostrictive element by fixing its one end and by making magnetic force act on the supermagnetostrictive element in the free end of the other end, wherein the rodlike supermagnetostrictive element is arranged between both end plates comprising a nonmagnetic body, wherein magnetic force generating means by electromagnets are arranged in a fixed end side and a free end side of the supermagnetostrictive element, on a coaxial line, and wherein the supermagnetostrictive element is continuously expanded and contracted by controlling current values of the magnetic force generating means to output the displacement to the free end side of the supermagnetostrictive element, and a device and a method are provided also using the micro-displacement controller. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a micro displacement control apparatus using a giant magnetostrictive element suitable for use in optical equipment, precision processing machines, laser equipment, measuring instruments, and other equipment that requires minute and precise displacement and feed, and in particular, a Belkovic indenter. For example, by a single indentation test of a thin film, the hardness is suitable for obtaining supplementary data on specific physical properties (for example, elastic modulus, creep property, Young's modulus) as well as absolute hardness values. The present invention relates to a micro-displacement control device suitable for measuring the thickness and the like, and an apparatus and method using the same.

  A conventional hardness tester using minute displacement control, for example, generates a load with a coil, transmits the force to a measurement indenter with a transmission lever, pushes the indenter into the sample, and measures the displacement at this time by a capacitance displacement meter. (For example, patent document 1).

  The following are known as measuring devices and actuators using giant magnetostrictive elements. For example, in the giant magnetostrictive actuator disclosed in Patent Document 2, a cylindrical permanent magnet, a giant magnetostrictive rod arranged along its central axis, and the upper end and the lower end of the casing are closed to form a closed magnetic circuit. A pair of upper and lower yokes are provided. In order to apply a magnetic bias to the giant magnetostrictive rod, an electromagnet formed by winding a coil around the giant magnetostrictive rod is disposed in a space surrounded by the permanent magnet and the yoke. A spring for prestressing the giant magnetostrictive rod is disposed between the casing and the yoke.

  According to this giant magnetostrictive actuator, a magnetic bias is applied to the giant magnetostrictive rod through a yoke by a permanent magnet, and a current is supplied to the electromagnet in a state where a prestress is applied by a spring. The giant magnetostrictive rod is expanded and contracted according to the size of the rod, the push rod provided at the tip of the giant magnetostrictive rod is moved, and the displacement is taken out as mechanical power.

  Further, as a measuring device or actuator using a giant magnetostrictive element, for example, the one shown in FIG. 1 is known (for example, Non-Patent Document 1). In the giant magnetostrictive element expansion / contraction control apparatus shown in FIG. 1, an electromagnet 103 is installed at the center of a U-shaped yoke 102, and the giant magnetostrictive element 101 is installed inside both ends of the yoke 102. This form is suitable for various magnetic field analyses, and the giant magnetostrictive element is hardly affected by heat even when an electric current is passed through the electromagnet.

Moreover, the following is known as an actuator provided with a coil for detecting the magnetic flux density inside the giant magnetostrictive element. For example, in the wire clamp mechanism disclosed in Patent Document 3, a drive coil that applies a magnetic flux to the giant magnetostrictive element and a detection coil that detects the magnetic flux density of the giant magnetostrictive element are installed. The change in the magnetic flux density of the giant magnetostrictive element can be taken out as an electrical signal by the detection coil.
JP 2001-124681 A JP 2002-58269 A Japanese Patent Laid-Open No. 10-178032 A. E. Clark, Hiroshi Eda, “Super Magnetostrictive Materials”, Nikkan Kogyo Shimbun, p. 103-105, 1995

  However, the hardness tester disclosed in Patent Document 1 uses a capacitance displacement meter for measuring the displacement of the indenter. Capacitance displacement meters are common in that they have a very high measurement resolution and enable nano-order measurement, but they are very sensitive to vibration because they are non-contact type. Further, the force transmission lever is balanced in a very unstable state around a fulcrum at a minute load. For these reasons, it is difficult to ensure a predetermined accuracy unless a substantial cost is applied to the vibration isolation table. Therefore, the entire apparatus is very expensive.

  Further, in the giant magnetostrictive actuator as disclosed in Patent Document 2, although the current supplied to the electromagnet can be reduced by the magnetic bias by the permanent magnet, in order to obtain sufficient expansion and contraction of the giant magnetostrictive rod. Requires a lot of current supply. As a result, Joule heat is generated in the coil, and the amount of heat generated is greatest at the center of the coil. On the other hand, the giant magnetostrictive element has a low relative magnetic permeability of about 10, so that unless a strong magnetic force is generated by an external magnetic force generator, the giant magnetostrictive element cannot be sufficiently magnetized and the amount of expansion and contraction can be increased. Can not. For this reason, as in Patent Document 2, a giant magnetostrictive element is arranged in the central part of the coil having the strongest magnetic force. As a result, the giant magnetostrictive element properly receives the Joule heat of the coil and easily undergoes thermal expansion. Due to this problem, precise control was difficult.

  Moreover, in the expansion / contraction control device for the giant magnetostrictive element as in Non-Patent Document 1, although the influence of Joule heat from the electromagnet on the giant magnetostrictive element can be reduced, the permeability of the giant magnetostrictive element is 10 from the value in air. In actuality, a considerable magnetic force leaked at the end of the yoke, and the giant magnetostrictive element could hardly be magnetized.

  Moreover, in the giant magnetostrictive actuator as disclosed in Patent Document 3, a detection coil is installed immediately next to the drive coil. Since the giant magnetostrictive element has a low magnetic permeability, the giant magnetostrictive element cannot be sufficiently magnetized unless a considerable current is supplied to the driving coil. For this reason, the detection coil simply detects the leakage magnetic flux generated from the driving coil. In addition, even when the length (width) of the driving coil and the detection coil is left as it is, the giant magnetostrictive element is lengthened, the driving coil and the detection coil are installed at both ends of the giant magnetostrictive element, and the distance between them is widened. Since the magnetic permeability of the giant magnetostrictive element is low, a large amount of magnetic flux leaks in the middle before the magnetic flux reaches the detection coil and returns to the driving coil. For these reasons, it has been difficult to accurately detect the magnetic flux density inside the giant magnetostrictive element.

  Focusing on the problems in the prior art as described above, the object of the present invention is basically a giant magnetostriction capable of controlling the amount of expansion and contraction and the displacement associated therewith without installing a giant magnetostrictive element in the coil. An object of the present invention is to provide an element expansion / contraction control apparatus, and to provide a minute displacement control apparatus that can obtain a target minute displacement with high accuracy using the element expansion / contraction control apparatus.

  Another object of the present invention is to enable various measurements and high-accuracy positioning by using such a minute displacement control device. For example, a non-contact displacement meter such as a capacitance displacement meter and Focusing on the above-mentioned problems of using a force transmission lever, basically using a magnetostrictive element expansion / contraction control device without using a non-contact displacement meter and force transmission lever, etc., extremely high accuracy It is an object of the present invention to provide a hardness measuring apparatus and method capable of measuring the load accompanying the pressing of the indenter.

  In order to solve the above-mentioned problems, a micro displacement control device according to the present invention has a free end that expands and contracts the giant magnetostrictive element by applying a magnetic force to the giant magnetostrictive element having one end fixed and the other end free. A device for controlling expansion and contraction of a giant magnetostrictive element that outputs an end displacement, wherein a rod-like giant magnetostrictive element is disposed between (inward) both end plates made of a non-magnetic material, and a fixed end side of the giant magnetostrictive element. Further, a magnetic force generating means by an electromagnet is arranged on the coaxial line on the free end side, and by controlling the current value of the magnetic force generating means, the super magnetostrictive element is continuously expanded and contracted so that the displacement is on the free end side of the super magnetostrictive element. The expansion and contraction control device for the giant magnetostrictive element is used to output a desired minute displacement by the displacement outputted to the free end side of the giant magnetostrictive element. That is, basically, the magnetic force applied to the giant magnetostrictive element is controlled by the means for generating the magnetic force from both ends of the giant magnetostrictive element, the giant magnetostrictive element is continuously expanded and contracted, and the displacement is moved to the free end side of the giant magnetostrictive element. It is made to output as a continuous displacement.

  The both end plates used here are preferably non-magnetic and heat insulating plates with low thermal conductivity. At this time, in order to increase the magnetic force applied to the giant magnetostrictive element, it is necessary to bring the giant magnetostrictive element as close as possible to the electromagnet. For this reason, a blind hole having substantially the same diameter as the giant magnetostrictive element is opened on both end plates, for example, from the giant magnetostrictive element side so as to leave a thickness of 1 mm of the free end plate and the fixed end plate, and the end of the giant magnetostrictive element is opened. insert. Thereby, the magnetic force from the magnetic force generating means can be applied to both ends of the giant magnetostrictive element in a desired state of a predetermined positional relationship, and the end plate is made of a non-magnetic material and a heat insulating plate having low thermal conductivity. Thus, the loss of magnetic force from the magnetic force generation means can be suppressed and the heat generation from the electromagnet can be blocked. Moreover, it is preferable that there is a gap larger than the displacement output to the free end side of the giant magnetostrictive element, for example, a gap of about 0.1 mm, between the iron core of the electromagnet and both end plates. Thereby, the displacement output to a free end side can be obtained reliably, and the further effect can be exhibited also with respect to the heat insulation with respect to heat conduction.

  In this way, without placing the giant magnetostrictive element in the center of the coil that generates the most Joule heat, the electromagnet coil, which is a heating element, and the giant magnetostrictive element are substantially completely thermally shut off via both end plates. And sufficient electromagnetism is obtained by making two electromagnets face each other and magnetizing efficiently from both ends of the giant magnetostrictive element. As a result, the expansion and contraction control of the giant magnetostrictive element can be performed very precisely without being affected by heat.

  Since the electromagnet, which is a magnetic force generating means, is disposed in the gap portion where the leakage magnetic flux increases most, even when the leakage magnetic flux is large, more magnetic flux can be transmitted to the giant magnetostrictive element. Moreover, the leakage magnetic flux at this time is immediately absorbed by the return side of each electromagnet, and there is little loss as a magnetic circuit.

  In a configuration in which two electromagnets are opposed to each other and a giant magnetostrictive element is disposed between them, an electromagnet end holding plate and a yoke (plate) for making the iron core of each electromagnet on the anti-giant magnetostrictive element side a magnetic closed circuit are attached. preferable. As a result, the magnetic force applied to the giant magnetostrictive element can be increased and the current value can be reduced, and the leakage magnetism can be reduced. This yoke can also serve as a frame of a device provided with a giant magnetostrictive element.

  Moreover, it is preferable to use what annealed electromagnetic soft iron (pure iron) for the iron core of an electromagnet, an electromagnet edge holding plate, and a yoke (plate). As a result, it is possible to further increase the magnetic force applied to the giant magnetostrictive element and reduce the current value.

  About the direction of the magnetic force by a magnetic force generation means, an electric current is sent through each electromagnet so that the opposing electromagnets may have different polarities. At this time, both the free end and the fixed end may have either S or N polarity, and it is only necessary that each has a different polarity. As a result, the magnetic force applied to the giant magnetostrictive element is made efficient.

  The wire diameter of the electromagnet coil is preferably about φ1 mm in order to prevent the generation of Joule heat as much as possible. Further, at this time, the number of turns of the coil is preferably 600 times or more, and the number of turns of both the coils is preferably the same, whereby a sufficient magnetic force can be applied to the giant magnetostrictive element.

  The current flowing through the coil of the electromagnet means that each end face of the giant magnetostrictive element is magnetized as evenly as possible, and it is preferable to always pass substantially the same value of current through the two electromagnets.

  The displacement output on the free end side is transmitted to the free end plate, and further transmitted to the output rod on the anti-super magnetostrictive element side of the free end side electromagnet via the connecting mechanism (for example, connecting plate) connected to the free end plate. Is done. At this time, the output rod is preferably arranged coaxially with the giant magnetostrictive element, and is preferably output linearly by a guide having a degree of freedom in only one direction such as a slide guide. As a result, the displacement amount of the giant magnetostrictive element is directly output without including an error, and a highly accurate output can be obtained.

  As the plate to which the output rod is fixed, a heat insulating plate having a low thermal conductivity is preferable, and it is possible to prevent the influence of heat on the anti-super magnetostrictive element side of the electromagnetic coil.

  Further, it is preferable that a means for applying prestress to the giant magnetostrictive element from the free end side of the giant magnetostrictive element is provided. For example, prestress can be applied by biasing means such as a spring through the free end plate or its attachment member. If such an urging means is provided, it becomes possible to press the free end plate on the free end side against the giant magnetostrictive element. And the rigidity of the entire apparatus in the feeding direction is improved, and more precise control is possible.

  Also, a detection coil can be provided in the central portion of the giant magnetostrictive element in the axial direction. Since the giant magnetostrictive element expands and contracts in proportion to the magnetic flux density in a certain area to be described later, if the magnetic flux density inside the giant magnetostrictive element can be accurately measured, the amount of expansion and contraction can be accurately grasped. In this device, electromagnets for generating magnetic force are arranged at both ends of the giant magnetostrictive element, so that it becomes possible to install a detection coil at the axial center of the giant magnetostrictive element, and the magnetic flux passing through the giant magnetostrictive element can be accurately measured. It is possible to measure. In addition, since the two electromagnets are sufficiently separated from each other, the magnetic flux density inside the giant magnetostrictive element can be accurately measured without detecting the leakage magnetic flux from the electromagnets.

  In addition, a large amount of leakage magnetic flux is generated in the gap from the iron core of the electromagnet to the giant magnetostrictive element. At this time, the leakage magnetic flux is generated on the immediate side of the two electromagnets. Absorbed to the side. In addition, the magnetic flux that has entered the inside of the giant magnetostrictive element instead of leaking magnetic flux is generated by the two electromagnets facing opposite poles from both ends of the giant magnetostrictive element. It becomes better and almost no leakage flux. Therefore, the vicinity of the center in the longitudinal direction of the giant magnetostrictive element is sufficiently separated from the influence of the magnetic flux of the electromagnet, and the influence of the leakage magnetic flux of the gap portion which is the largest leakage magnetic flux generating portion in this apparatus is also affected. In addition, since the leakage magnetic flux inside the giant magnetostrictive element is small, it is optimal for detecting the magnetic flux density inside the giant magnetostrictive element.

  The giant magnetostrictive element has a large expansion / contraction hysteresis. However, if the magnetic flux density inside the giant magnetostrictive element is accurately measured and fed back, the expansion / contraction can be controlled without a problem of hysteresis.

  A permanent magnet can be installed in order to apply a bias magnetic force in the axial direction of the giant magnetostrictive element. When there is no bias magnetic force, when a magnetic force is applied to the giant magnetostrictive element by an electromagnet, initially, the magnetic flux density inside the giant magnetostrictive element by the detection coil is not proportional to the output of this apparatus. When a magnetic force is applied to some extent, the magnetic flux density inside the giant magnetostrictive element is proportional to the output of this device. If a bias magnetic force is applied in advance by an electromagnet or permanent magnet to the area where the magnetic flux density inside the giant magnetostrictive element is proportional to the amount of displacement, control is performed with the magnetic flux density inside the giant magnetostrictive element and the output of this device in proportion. Is possible. In short, the detection coil must be used with a bias magnetic field applied to the giant magnetostrictive element.

  The bias magnetic field generated by the electromagnet is previously energized to the electromagnet by the two electromagnets for expansion / contraction of the giant magnetostrictive element in the same direction as the giant magnetostrictive element expands / contracts.

  The bias magnet may be installed by installing a hollow cylindrical permanent magnet magnetized in the axial direction outside the giant magnetostrictive element, or by installing two cylindrical permanent magnets at opposite ends with opposite poles facing each other. May be. In short, it may be installed so that a bias magnetic force is applied in the axial direction of the giant magnetostrictive element and in the same direction as the electromagnet.

  Alternatively, the giant magnetostrictive element can be divided into two parts, and a Hall element enclosed in a magnetic force measuring device, for example, a guide made of a non-magnetic material, can be installed in the divided part. As a result, the magnetic flux passing through the giant magnetostrictive element can be accurately measured, and the expansion and contraction can be accurately controlled.

  Such a micro displacement control device provided with the expansion / contraction control device for a giant magnetostrictive element according to the present invention can be applied to various devices that require fine and precise feeding and output, for example, using this micro displacement control device, An ultra-micro hardness measuring device can be configured. That is, the measurement device for hardness or the like according to the present invention is configured to transfer the displacement output to the free end side of the giant magnetostrictive element by the expansion / contraction control device of the giant magnetostrictive element in the minute displacement control apparatus as described above to the object to be measured. The amount of indentation is measured using a load measuring device, and the load corresponding to the amount of indentation is measured to obtain the "indentation amount-load" characteristics and hardness value of the object to be measured. Consists of.

  For example, as shown in the drawings described later, in the measurement with this ultra-micro hardness measuring device, a load measuring device, for example, a piezoelectric load cell, is installed on the same axis as the output shaft of this device. Further, for example, a Belkovic diamond indenter is attached upward on the piezoelectric load cell. The contact between the indenter and the measurement sample at this time is detected by a piezoelectric load cell, and the position of the indenter at this time is set as a zero point. As for the positional relationship between the sample setting plate on which the measurement sample is set and the Belkovic diamond indenter, for example, a sample setting plate with a hole of about φ2 mm is set on the upper part of the Belkovic diamond indenter. At this time, the hole opened in the sample setting plate and the Belkovic diamond indenter are arranged on the coaxial line so that the tip of the Berkovich diamond indenter is slightly retracted from the sample setting plate. The state before the measurement is the shortest state of the expansion / contraction stroke of this apparatus. The sample surface to be measured is placed downward on the sample setting plate, and fixed with, for example, a permanent magnet. Next, when a current is passed through the device to expand and contract the giant magnetostrictive element, the tip of the Belkovic diamond indenter comes out of the hole in the sample setting plate, and the indenter is pushed into the measurement sample surface. The position control of the indenter at this time is continuously performed, for example, at a constant speed by feedback control by a detection coil, and the load at this time is continuously read by the load meter. This is similarly performed in the indenter return direction until the load becomes zero. Thereby, a graph of “push amount-load” characteristic can be created, a continuous characteristic curve can be obtained, and the hardness value of each measurement point can be obtained. Since this characteristic curve varies depending on the material, it becomes possible to obtain a comparative examination of physical property evaluation and physical property data such as Young's modulus.

  In this microhardness measuring apparatus, the giant magnetostrictive element, the output rod, the piezoelectric load cell, and the indenter are arranged on the coaxial line, and there is no non-contact portion. These are advantageous in terms of accuracy in terms of Abbe's principle, and also have a positive effect on vibration resistance.

  As another push-in method for the ultra-small hardness measuring device having such a configuration, the position control of the indenter is continuously performed at a constant speed by feedback control using, for example, a detection coil, and the load at this time Is continuously read by the load cell. This is performed up to the set push-in amount. Next, for example, without measuring the indenter push-in amount and load in the return direction, quickly pull out the indenter, and then perform the second push on the same part up to the same amount as the first push-in, and continue the load at that time. (Reading indenter push-in amount and load in the return direction are not measured). Thereby, the first time becomes a curve including both elastic and plastic deformation, but the second time can obtain a curve of only elastic deformation. As a result, it is possible to obtain a measurement curve equivalent to the above method of measuring both the going and returning directions with a single push. Also, by measuring the timing of the second push, it is possible to see the time function of the elastic recovery of the measurement sample.

  The indenter pushing device used for such a measuring method is naturally possible with the present minute displacement control device, but can also be a minute displacement device having hysteresis. For example, a piezo actuator has hysteresis in the extension direction and the return direction. However, if only the extension direction is used, it can be extended linearly even by control using an open loop. Therefore, it is possible to perform the same measurement as the measurement method by using the extension in the extension direction that can be precisely controlled twice.

  For example, it is possible to take a form as shown in FIG. In the measurement by the ultra-small hardness measuring apparatus, the portal frame 25 and the base board 27 are connected, and an electronic balance 26 is placed on the base board 27, for example. Further, a means (coarse moving section 24) capable of moving coarsely is placed on the electronic balance 26. In this device, the output portion of the minute displacement control device 28 is fixed downward on the top plate of the portal frame 25. For example, a Berkovich diamond indenter 20 is attached to the output portion of this apparatus, and a sample setting plate 21 on which a measurement sample 23 is set is attached to a movable coarse adjustment unit 24. The giant magnetostrictive element is expanded and contracted at the shortest position of the expansion and contraction stroke of this apparatus. Next, the coarse adjustment moving unit 24 that can be fixed is moved and fixed until the indenter 20 contacts the measurement material 23. The contact confirmation at this time is performed by checking the value of the electronic balance 26 and the like. Next, the indenter 20 is continuously pushed in accurately by this apparatus. The load at that time is continuously read by the electronic balance 26 or the like. This is performed up to the set final push amount. Further, this is performed in the same manner in the return direction of the indenter 20 until the load becomes zero. Thereby, a graph of “push amount-load” characteristic can be created, a continuous characteristic curve can be obtained, and the hardness value of each measurement point can be obtained. Since this characteristic curve varies depending on the material, it is possible to compare and evaluate physical properties.

  In this minute displacement control device, for example, about 20 kgf of pre-stress by an urging means such as a spring is applied, so the rigidity of the giant magnetostrictive element and the entire system is very high. On the other hand, since the maximum load at the time of micro-indentation (several μm or less) is very small at several tens of grams or less, the elastic deformation of the device at the time of indentation can be ignored. Therefore, it can be regarded that “the amount of displacement by this device after contacting the sample” = “the amount of pressing the indenter”.

  Moreover, in such a measuring apparatus, it is desirable to combine with a load measuring apparatus capable of measuring a load without accompanying displacement. For this purpose, a load measuring device such as a piezoelectric element or an electronic balance is suitable.

  Since this minute displacement control device enables nano-order indentation, it can be used in combination with a minute load measuring device such as a piezoelectric element to measure the hardness of a thin film having a thickness of several microns. Moreover, by obtaining a continuous curve of the “push-in amount-load” characteristic, it is possible to analyze not only the hardness but also mechanical properties such as elastic modulus and Young's modulus of a thin film.

  Since the micro displacement control device used in this indenter pushing unit uses expansion and contraction as a material of the giant magnetostrictive element, it is not affected by vibration at all. Thereby, even if the vibration isolator of this micro micro hardness measuring apparatus is simple, there is no problem. Therefore, it becomes possible to provide a highly accurate device at a low cost as the whole measuring apparatus.

  Further, the micro displacement control device using the super magnetostrictive element expansion / contraction control device according to the present invention as described above can be applied to various devices that require minute and precise feeding and output. By using it, a displacement sensor calibration device can be configured. That is, the displacement sensor calibration apparatus according to the present invention reads the displacement output to the free end side of the giant magnetostrictive element by the giant magnetostrictive element expansion / contraction control apparatus in the minute displacement control apparatus as described above, By contrasting with the output of the displacement sensor, the output of the target displacement sensor is calibrated or the performance test is performed. In many cases, the displacement sensor inputs and calibrates any two or three proportional points within the measured displacement range.

  For example, even in the case of a high-precision displacement sensor having nano-order resolution, the zero point / span adjustment of the measurement output (inclination of the output straight line) is performed by changing the thickness of the block gauge. However, with such a high-precision displacement sensor, the accuracy of calibration is poor in a block gauge with sub-micron order variations. Therefore, for example, in the case of a laser displacement sensor, a laser is irradiated to the output portion of the minute displacement control device according to the present invention. And it outputs so that an output may become a straight line using this micro displacement control apparatus. Then, the output of the laser displacement sensor is targeted, and the zero point / span adjustment (inclination of the output straight line) of the laser displacement sensor is performed so that the straight line inclinations coincide.

  It is also possible to install a sensor (in the same direction as the output direction) at the output portion of the minute displacement control device. With this configuration, it is possible to calibrate using an actual object to be measured. If the sensor and the output portion of this apparatus are aligned in advance, it is possible to calibrate more quickly and accurately. A sensor here is a displacement sensor, an absolute length sensor, a strain gauge, etc., and does not ask | require contact and non-contact.

  Further, it is also possible to drive in steps by feeding back a signal from a detection coil of the minute displacement control device and controlling an input current to the minute displacement control device. By making this step fine, the resolution of the target sensor can be known. Similarly, the linearity of the target sensor can be examined by outputting the minute displacement control device at a constant speed by feedback control. As described above, the performance test of the target sensor can be performed.

  Further, the micro displacement control device using the super magnetostrictive element expansion / contraction control device according to the present invention as described above can be applied to various devices that require minute and precise feeding and output. By using it, a positioning stage can be configured. That is, in the positioning stage according to the present invention, the stage is positioned by the displacement output to the free end side of the super magnetostrictive element by the super magnetostrictive element expansion / contraction control apparatus in the micro displacement control apparatus as described above. It consists of what is characterized by this. More specifically, for example, an output portion of the minute displacement control device is connected to a slide guide that can slide precisely in only one direction. At this time, if a device provided with the previous detection coil or the like is used, the reciprocating positioning operation can be performed accurately without being affected by hysteresis. Furthermore, the X / Y stage can be configured by superimposing the one-direction stage by shifting by 90 °. Of course, the vertical stage can be further combined into an X, Y, and Z stage, and the combination of positioning directions can be set arbitrarily.

  Similarly, in the method according to the present invention, it is possible to perform measurement and positioning at various places using the micro displacement control device provided with the expansion / contraction control device for the giant magnetostrictive element according to the present invention.

  That is, the measurement method of hardness or the like according to the present invention uses the minute displacement control device as described above, and is measured by the displacement output to the free end side of the giant magnetostrictive element by the expansion and contraction control device of the giant magnetostrictive element. A method of controlling an amount of indentation into an object, measuring a load corresponding to the amount of indentation using a load measuring device, and obtaining a “indentation amount-load” characteristic and a hardness value of the object to be measured. Consists of.

  Further, the displacement sensor calibration method according to the present invention uses the minute displacement control device as described above, the displacement output to the free end side of the giant magnetostrictive element by the expansion and contraction control device of the giant magnetostrictive element, and the target displacement. The method is characterized in that the output of the target displacement sensor is calibrated or the performance is tested by contrasting with the output of the sensor.

  Furthermore, the positioning stage control method according to the present invention uses the above-described minute displacement control device, and the displacement output to the free end side of the giant magnetostrictive element by the expansion and contraction control device of the giant magnetostrictive element causes the stage to move. It consists of the method characterized by performing positioning.

  According to the micro displacement control device according to the present invention as described above, the amount of expansion / contraction of the giant magnetostrictive element can be maximized without being affected by the heat generated by the electromagnet, and the giant magnetostrictive element can be accurately detected by the detection coil. It is possible to control the amount of expansion and contraction to the nano order with high accuracy by controlling the current value of the electromagnet without being affected by the hysteresis of the giant magnetostrictive element. Become. Moreover, since the number of parts is small with a simple device configuration, it can be manufactured at low cost.

  Further, according to various measuring devices, calibration devices, positioning devices and methods using such a micro displacement control device according to the present invention, desired hardness measurement, sensor calibration, positioning, etc. can be performed with extremely high accuracy and It can be performed easily and with an inexpensive apparatus.

Preferred embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 3 shows a minute displacement control device provided with the expansion / contraction control device for a giant magnetostrictive element according to an embodiment of the present invention. The expansion / contraction control device for the giant magnetostrictive element 2 in the minute displacement control device 1 according to the present invention shown in FIG. 3 includes the giant magnetostrictive element 2 having one end fixed and the other end being a free end, and two electromagnets 5. The giant magnetostrictive element 2 is expanded and contracted by a magnetic force change by controlling the current values of the two electromagnets 5 and the displacement is output to the free end. In FIG. 3, a rod-shaped giant magnetostrictive element 2 is arranged (inside) between a free end plate 4 and a fixed end plate 3 made of a nonmagnetic material, and the fixed end of the giant magnetostrictive element 2 is outside the both end plates. The electromagnet 5 is arranged on the same line on the side and the free end side, and the current value of the electromagnet 5 is controlled, whereby the super magnetostrictive element 2 is continuously expanded and contracted, and the displacement is moved to the free end side of the super magnetostrictive element 2. It is made to output.

  The electromagnet 5 is attached to the yoke plate 12 which also serves as a frame together with the electromagnet end holding plate 13 to constitute a magnetic closed circuit. As a result, the magnetic force applied to the giant magnetostrictive element 2 can be increased and the current value can be reduced, and the leakage magnetism can be reduced. The connecting plate 14 connects the free end plate 4 and the output plate 8, and transmits the output of the free end plate 4 to the output rod 11. At this time, the output rod 11 is arranged on the same axis as the giant magnetostrictive element 2 and is linearly output by the slide bush 10 fitted in the slide housing 9 having a degree of freedom only in the axial direction. With such a configuration, the displacement amount of the giant magnetostrictive element 2 is directly output without any error, and a highly accurate output can be obtained.

  Four urging means by the tension spring 7 are attached to the connecting plate 14. If such an urging means is provided, it becomes possible to press the free end plate 4 on the free end side against the giant magnetostrictive element 2, whereby prestress is applied to the giant magnetostrictive element 2. The expansion and contraction characteristics are improved, and the rigidity in the feed direction is improved, enabling more precise control.

  For the output plate 8 to which the output rod 11 is fixed, a heat insulating plate having a low thermal conductivity is used. Thereby, the influence by the heat | fever on the anti- super magnetostrictive element side of the electromagnet 5 is prevented.

  As the giant magnetostrictive element 2, in the present embodiment, a cylindrical “ETREMATERFENOL-D” manufactured by Etorima is used. The size is φ6mm × 25mm.

  In this way, the coil of the electromagnet 5 that is a heating element and the supermagnetostrictive element 2 are thermally cut off without arranging the supermagnetostrictive element 2 at the center of the coil of the electromagnet 5 that generates the largest amount of Joule heat, and the electromagnet Since the two different polarities face each other and are efficiently magnetized from both ends of the giant magnetostrictive element 2, a sufficient amount of expansion and contraction is obtained. Thereby, it is possible to control the expansion and contraction very precisely without being affected by heat.

  The free end plate 4 and the fixed end plate 3 used here are non-magnetic and heat insulating plates having low thermal conductivity. At this time, in order to increase the magnetic force applied to the giant magnetostrictive element 2, it is necessary to bring the giant magnetostrictive element 2 as close as possible to the electromagnet 5. Therefore, a blind hole having the same diameter (φ6 mm) as that of the giant magnetostrictive element 2 is formed in the free end plate 4 and the fixed end plate 3 from the giant magnetostrictive element 2 side while leaving the free end plate 4 and the fixed end plate 3 with a thickness of 1 mm. A giant magnetostrictive element 2 is provided. Thereby, the magnetic force from the electromagnet 5 can be applied to both ends of the giant magnetostrictive element 2 in a desired state of a predetermined positional relationship, and the plate is made of a heat insulating plate having a non-magnetic material and low thermal conductivity. The loss of magnetic force from the electromagnet 5 can be suppressed, and the heat generation from the electromagnet 5 can be blocked. Further, the iron core 6 of the electromagnet 5, the free end plate 4 and the fixed end plate 3 are provided with a gap of about 0.1 mm. Thereby, the displacement output to the free end side can be obtained, and a further effect can be exhibited in measures against heat conduction.

  The electromagnet iron core 6 (φ6 mm), the electromagnet end holding plate 13 and the yoke plate 12 are magnetically annealed electromagnetic soft iron (pure iron). Thereby, it is possible to further increase the magnetic force applied to the giant magnetostrictive element 2 and reduce the current value.

  About the direction of the magnetic force by the electromagnet 5, an electric current is sent through each coil so that the electromagnet 5 which opposes may become a different polarity. As a result, the magnetic force applied to the giant magnetostrictive element 2 is made efficient.

  In order to prevent the generation of Joule heat as much as possible, the coil diameter of the electromagnet 5 is φ1 mm, and the number of turns of the coil is about 600 times. As a result, a sufficient magnetic force can be applied to the giant magnetostrictive element 2.

  The current flowing through the coil of the electromagnet 5 means that the end faces of the giant magnetostrictive element 2 are magnetized as evenly as possible, and the two electromagnets 5 are always controlled to flow the same current value.

  In addition, a detection coil 15 is provided in the central portion of the giant magnetostrictive element 2 in the axial direction. In order to accurately detect the magnetic flux density only inside the giant magnetostrictive element 2, the detection coil 15 is as far as possible from the electromagnets 5 at both ends and is not in close contact with the outer diameter (φ6 mm) of the giant magnetostrictive element 2. Must not. Therefore, this apparatus uses a coil having a wire diameter of φ0.03 mm, an inner diameter of φ6 mm, an outer diameter of φ6.45 mm, a width of 2 mm, and a winding number of 300.

  Since the giant magnetostrictive element 2 expands and contracts in proportion to the magnetic flux density in the region described later, if the magnetic flux density inside the giant magnetostrictive element 2 can be accurately measured, the amount of expansion and contraction can be accurately grasped. . In this apparatus, since the electromagnets 5 for generating magnetic force are arranged at both ends of the giant magnetostrictive element 2, it is possible to install the detection coil 15 at the center in the axial direction of the giant magnetostrictive element 2. It is possible to accurately measure the internal magnetic flux density.

  For example, as shown in FIG. 4, the giant magnetostrictive element 2 has a large expansion / contraction hysteresis. However, if the magnetic flux density inside the giant magnetostrictive element 2 is accurately measured and fed back, the expansion / contraction can be controlled without a problem of hysteresis. It becomes.

  In order to apply a bias magnetic force in the axial direction of the giant magnetostrictive element 2, a cylindrical permanent magnet 16 is provided. When there is no bias magnetic force, when the magnetic force is applied to the giant magnetostrictive element 2 by the electromagnet 5, the magnetic flux density inside the giant magnetostrictive element 2 by the detection coil 15 is not proportional to the output of this apparatus. When a certain amount of magnetic force is applied, the magnetic flux density inside the giant magnetostrictive element 2 is proportional to the output of this device (FIG. 5). Since the giant magnetostrictive element 2 is also a ferromagnetic material, it is considered that it is magnetized like the initial magnetization curve as shown in FIG. In the initial permeability range, the magnetic flux density inside the giant magnetostrictive element 2 and the output of this device are not proportional, but in the irreversible domain wall movement range. When a bias magnetic field is applied in advance to the region where the magnetic flux density inside the giant magnetostrictive element 2 is proportional to the amount of displacement, control is performed in which the magnetic flux density inside the giant magnetostrictive element 2 and the output of this device are proportional. (Fig. 7). In short, the detection coil must be used with a bias magnetic field applied to the giant magnetostrictive element. The bias magnetic force at this time is about 500G.

  Further, when performing more precise expansion / contraction control, it is desirable to perform expansion / contraction control without expanding / contracting the giant magnetostrictive element to the rotational magnetization range in FIG. FIG. 8 shows the static characteristics of the detection coil with respect to the capacitive displacement meter. As shown in FIG. 8, if the direction of increase in the input current exceeds the initial permeability range, a comparison with the capacitive displacement meter is made. Is linear. However, as shown in FIG. 9, the input current decreasing direction has a slightly curved characteristic, and a slight hysteresis is observed in the input current increasing direction and the input current decreasing direction. Therefore, when strictly controlling expansion / contraction with high accuracy, it is desirable to perform expansion / contraction control in the irreversible domain wall movement range without expanding / contracting the giant magnetostrictive element 2 to the rotational magnetization range.

  When the expansion / contraction control is performed without applying the bias magnetic field and expanding / contracting the giant magnetostrictive element to the rotational magnetization range, both the input current increasing direction and the input current decreasing direction are linear as shown in FIGS. Thus, high-precision expansion / contraction control without hysteresis becomes possible. In addition, conversion of the voltage value and displacement amount of the capacitive displacement meter of FIGS. 8 to 11 is 1 V = 2.5 μm.

  Also, the giant magnetostrictive element 2 can be divided into two parts, and a Hall element enclosed in a magnetic force measuring device, for example, a guide made of a non-magnetic material, can be installed in the divided part. As a result, the magnetic flux passing through the giant magnetostrictive element can be accurately measured, and the expansion and contraction can be accurately controlled.

  As shown in FIG. 12, in the measurement by the ultra-micro hardness measurement device 31, the piezoelectric load cell 22 (for example, manufactured by PCB: 209C12) is placed on the same axis as the output rod 11 of this device. Type) is installed. Further, a Belkovic diamond indenter 20 is mounted upward on the piezoelectric load cell 22. Further, a sample installation plate 21 having a hole of about φ2 mm is installed on the upper part of the Belkovic diamond indenter 20, and the sample installation plate 21 is vertically moved by a block gauge 29 installed on the surface smooth plate 30. The position is adjusted in the direction. At this time, the hole opened in the sample setting plate 21 and the Belkovic diamond indenter 20 are arranged on the coaxial line so that the tip of the Belkovic diamond indenter 20 is slightly retracted from the sample setting plate 21. The state before the measurement is the shortest state of the expansion / contraction stroke of this apparatus. The measurement sample surface is placed downward on the sample setting plate 21 and fixed with a permanent magnet. Next, when a current is passed through the device to expand and contract the giant magnetostrictive element 2, the tip of the Berkovich diamond indenter 20 comes out from the hole of the sample setting plate 21, and the Berkovich diamond indenter 20 is pushed into the measurement sample surface. At this time, the position control of the Belkovic diamond indenter 20 is continuously performed so as to become a constant speed by feedback control by the detection coil 15, and the load at this time is continuously read by the piezoelectric load cell 22. This is performed in the same manner in the returning direction of the Belkovic diamond indenter 20 until the load becomes zero.

  Thereby, a graph of “push amount-load” characteristic can be created, a continuous characteristic curve can be obtained, and the hardness value of each measurement point can be obtained. Since this characteristic curve varies depending on the material, it becomes possible to obtain a comparative examination of physical property evaluation and physical property data such as Young's modulus.

  In this microhardness measuring apparatus, the giant magnetostrictive element, the output rod, the piezoelectric load cell, and the indenter are arranged on the coaxial line, and there is no non-contact portion. These are advantageous in terms of accuracy in terms of Abbe's principle, and also have a positive effect on vibration resistance.

  In this apparatus, for example, the prestress by the biasing means of the tension spring is applied by about 20 kgf, so that the rigidity of the giant magnetostrictive element and the entire system is very high. On the other hand, since the maximum load at the time of micro-indentation (several μm or less) is only a few tens of grams or less, the elastic deformation of this device at the time of indentation can be ignored. Therefore, it can be regarded that “the amount of displacement by this device after contacting the sample” = “the amount of pressing the indenter”.

  Moreover, in such a measuring apparatus, it is desirable to combine with a load measuring apparatus capable of measuring a load without accompanying displacement. For this purpose, a load measuring device such as a piezoelectric load cell or an electronic balance is suitable.

  This super magnetostrictive element expansion / contraction control device enables nano-order push-in, so it can be used in conjunction with a micro-load measuring device such as a piezoelectric load cell to measure the hardness of thin films with a thickness of several microns. . Moreover, by obtaining a continuous curve of the “push-in amount-load” characteristic, it is possible to analyze not only the hardness but also mechanical properties such as elastic modulus and Young's modulus of a thin film.

  Further, in this apparatus, in FIG. 13, the characteristic curve passing through the zero point of the indenter push amount and the load shows the characteristic at the time of push-in, and the other characteristic curve shows the characteristic at the time of the push-in amount decreasing (return direction). In addition, there is hysteresis between the two. The characteristic at the time of indentation has hardness of both “elastic component + plastic component”, but the characteristic at the time of indentation reduction (return direction) represents the hardness of only “elastic component”. As described above, since the elastic component and the plastic component can be separated, it is possible to obtain various physical property data such as Young's modulus as well as the hardness value.

  The expansion / contraction control device for the giant magnetostrictive element used in this indenter pushing unit uses the extension / contraction as a material of the giant magnetostrictive element, and is not affected by vibration at all. Thereby, even if the vibration isolator of this ultra-micro hardness measuring machine is simple, there is no problem. Therefore, it is possible to provide highly accurate products at low cost.

  In addition, the measurement of the said expansion-contraction amount (FIG.4, FIG.5, FIG.7-FIG. 11) was performed using the Japan ADI Co., Ltd. electrostatic capacitance type displacement meter "microsense 3401HR-01".

  The minute displacement control device according to the present invention can be applied to optical equipment, precision processing machines, laser equipment, measuring instruments, and other equipment in various fields that require minute and precise displacement and feeding. It can be suitably applied to hardness measurement of thin films that are difficult to measure, measurement of specific physical properties such as elastic modulus, creep characteristics, Young's modulus, calibration of a micro displacement sensor, micro positioning stage, and the like.

It is a schematic block diagram of the expansion-contraction control apparatus of the conventional giant magnetostrictive element. It is a schematic block diagram which shows the structural example of an ultra micro hardness measuring machine. It is a schematic block diagram of the micro displacement control apparatus which concerns on one embodiment of this invention. It is a characteristic view which shows an example of the hysteresis of the expansion-contraction amount of a giant magnetostrictive element. It is a characteristic view of the magnetic flux density (detection coil output voltage) inside the giant magnetostrictive element with respect to the displacement amount of the giant magnetostrictive element when there is no bias magnetic field. It is an initial magnetization curve. It is a characteristic view of the magnetic flux density (detection coil output voltage) inside the giant magnetostrictive element with respect to the displacement amount of the giant magnetostrictive element when there is a bias magnetic field. It is a characteristic view of the input current increasing direction when the giant magnetostrictive element is expanded and contracted to the rotational magnetization range. It is a characteristic view of the input current decreasing direction when the giant magnetostrictive element is expanded and contracted to the rotational magnetization range. It is a characteristic view of the input current increasing direction when the giant magnetostrictive element is not expanded and contracted to the rotational magnetization range with a bias magnetic field. FIG. 10 is a characteristic diagram in the direction of decreasing input current when the giant magnetostrictive element is not expanded and contracted to the rotational magnetization range with a bias magnetic field. It is a schematic block diagram of the ultra-micro hardness measuring apparatus which concerns on one embodiment of this invention. It is a characteristic view which shows an example of the "push amount-load" characteristic curve by this apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Minute displacement control apparatus 2 Giant magnetostrictive element 3 Fixed end plate 4 Free end plate 5 Electromagnet 6 Iron core 7 Pull spring 8 Output plate 9 Slide housing 10 Slide bush 11 Output rod 12 Yoke plate 13 Electromagnet end holding plate 14 Connection plate 15 Detection Coil 16 Permanent magnet 20 Belkovic diamond indenter 21 Sample installation plate 22 Piezoelectric load cell 23 Measurement sample 24 Coarse moving unit 25 Portal frame 26 Electronic balance 27 Base panel 28 Micro displacement control device 29 Block gauge 30 Surface smooth plate 31 Super fine Small hardness measuring device

Claims (19)

  A device for controlling expansion and contraction of a giant magnetostrictive element in which one end is fixed and the other end is freed by causing a magnetic force to act on the giant magnetostrictive element to expand and contract the giant magnetostrictive element and output the displacement of the free end. In addition, a rod-shaped super magnetostrictive element is arranged between both end plates made of a non-magnetic material, and a magnetic force generating means by an electromagnet is arranged on the coaxial line on the fixed end side and the free end side of the super magnetostrictive element and outside the both end plates. Then, by controlling the current value of the magnetic force generating means, using the expansion / contraction control device for the giant magnetostrictive element that continuously expands and contracts the giant magnetostrictive element and outputs the displacement to the free end side of the giant magnetostrictive element, A minute displacement control device characterized in that a target minute displacement is obtained by a displacement output to the free end side of the giant magnetostrictive element.   The minute displacement control device according to claim 1, wherein the both end plates are made of a nonmagnetic material having low thermal conductivity.   The minute displacement control device according to claim 1 or 2, wherein both ends of the giant magnetostrictive element are inserted into blind holes having substantially the same diameter as the giant magnetostrictive element provided on the both end plates.   The gap larger than the displacement output to the free end side of the giant magnetostrictive element is provided between the iron core of the electromagnet and the end plate on the free end side of the giant magnetostrictive element. The micro displacement control device described.   The micro displacement according to any one of claims 1 to 4, wherein a yoke for making the iron core on the side opposite to the super-magnetostrictive element of the two electromagnets into a magnetic closed circuit is provided for the two electromagnets arranged on the coaxial line. Control device.   6. The minute displacement control device according to claim 5, wherein an electromagnetic soft iron that has been magnetically annealed is used for the iron core and yoke of the electromagnet.   The minute displacement control device according to any one of claims 1 to 6, wherein substantially the same current flows in the coils of both electromagnets.   The displacement output to the free end side of the giant magnetostrictive element is transmitted to the output rod disposed on the coaxial line with the giant magnetostrictive element via the end plate on the free end side and the connecting mechanism connected to the end plate. The micro displacement control device according to claim 1.   The micro displacement control device according to claim 8, wherein the output rod is fixed to a member having low thermal conductivity.   The micro displacement control device according to any one of claims 1 to 9, further comprising means for prestressing the giant magnetostrictive element from a free end side of the giant magnetostrictive element.   The micro displacement control device according to claim 1, wherein a detection coil capable of measuring a magnetic flux density inside the giant magnetostrictive element is provided at a central portion in the axial direction of the giant magnetostrictive element.   The micro displacement control device according to claim 1, wherein a permanent magnet capable of applying a bias magnetic force to the super magnetostrictive element in an axial direction of the super magnetostrictive element is provided.   The micro displacement control device according to any one of claims 1 to 12, wherein the electromagnet is energized in advance so that a bias magnetic field is generated by the electromagnet with a polarity in the same direction as the expansion and contraction direction of the giant magnetostrictive element.   The displacement output to the free end side of the giant magnetostrictive element by the expansion / contraction control device of the giant magnetostrictive element in the minute displacement control apparatus according to any one of claims 1 to 13 is set as an indentation amount into the object to be measured, and load measurement An apparatus for measuring hardness or the like, characterized in that a load corresponding to the indentation amount is measured using an apparatus to obtain a “indentation amount-load” characteristic and a hardness value of an object to be measured.   By comparing the displacement output to the free end side of the giant magnetostrictive element by the expansion / contraction control device of the giant magnetostrictive element in the minute displacement control device according to any one of claims 1 to 13, and the output of the target displacement sensor. An apparatus for calibrating a displacement sensor, wherein the output of the target displacement sensor is calibrated or a performance test is performed.   The stage is positioned by the displacement output to the free end side of the super magnetostrictive element by the expansion / contraction control apparatus of the super magnetostrictive element in the micro displacement control apparatus according to any one of claims 1 to 13. A positioning stage.   The amount of indentation into the object to be measured is controlled by the displacement output to the free end side of the giant magnetostrictive element by the expansion and contraction control device of the giant magnetostrictive element using the micro displacement control apparatus according to any one of claims 1 to 13. And measuring a load corresponding to the indentation amount using a load measuring device to obtain a “indentation amount-load” characteristic and a hardness value of the object to be measured.   The displacement output to the free end side of the super magnetostrictive element by the expansion / contraction control apparatus of the super magnetostrictive element is compared with the output of the target displacement sensor using the micro displacement control apparatus according to claim 1. A calibration method for the displacement sensor, wherein the calibration of the output of the target displacement sensor or the performance test is performed.   14. The stage is positioned by the displacement output to the free end side of the super magnetostrictive element by the super magnetostrictive element expansion / contraction control apparatus using the micro displacement control apparatus according to claim 1. A method for controlling the positioning stage.

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