JP4731146B2 - Management control method of apparatus having movable part and precision driving apparatus using the same - Google Patents

Description

  The present invention relates to a precision drive device, and is particularly suitable for use in precision processing machines, precision measurement devices, and semiconductor manufacturing devices.

  Ultrasonic motors have the features that the minimum amplitude is as small as nanometer order, positioning with high resolution is possible, and the driving force is large because of frictional drive. Practical application to a rotational motion system such as a vibration alarm has been made, and recently, application to a precision motion device of a linear motion system such as a precision processing machine, a precision measurement device, a semiconductor manufacturing device, etc. has been attempted.

  FIG. 4 shows a conventional precision drive device 10 which is one example of application to a linear motion system precision drive device. This apparatus is provided with a pair of guide members 12 such as cross roller guides on a base board 11 and linearly guides a stage 13 as a movable body by these guide members 12.

  A driving force transmission member 14 is installed on one side surface of the stage 13 in parallel with the guide member 12, and a linear scale 15 is installed on the other side surface of the stage 13 in parallel with the driving force transmission member 14. A measuring head 16 is provided at a position facing the linear scale 15 to constitute a position detecting means 17, and two ultrasonic motors 20 are installed at a position facing the driving force transmitting member 14. The friction member 25 of each ultrasonic motor 20 is brought into contact with the contact surface of the driving force transmission member 14 perpendicularly.

  In the figure, reference numeral 26 denotes a case for housing the ultrasonic motor 20, reference numeral 27 denotes a spring for holding the ultrasonic motor 20 in the case 26 without obstructing the driving of the ultrasonic motor 20, and reference numeral 28 denotes a drive for the stage 13. A spring for pressing the force transmission member 14. Reference numeral 18 denotes a drive control unit for controlling the drive speed of the stage 13 on the basis of the position information obtained from the position detection means 17. The drive control unit 18 is based on the drive command signal output from the drive control unit 18. The sonic motor 20 is driven.

  The friction member 25 and the driving force transmission member 14 are made of general ceramics, glass, or the like, and are brought into contact with each other to drive the stage 13 by friction driving.

  Further, as shown in FIGS. 5A and 5B, the structure of the ultrasonic motor 20 used in the precision driving apparatus 10 shown in FIG. The electrode films 22a, 22b, 22c, and 22d are divided, and the diagonal electrode films 22a and 22d are connected, the diagonal electrode films 22b and 22c are connected, and The other main surface is composed of a vibrating body 24 having an electrode film 23 formed on almost the entire surface and a friction member 25 made of ceramics or glass provided on the end surface of the piezoelectric ceramic plate 21 and formed on the one main surface. The grounded electrode film 23 is grounded, and by applying voltages having different phases to the electrode film 22a and the electrode film 22b formed on the other main surface, longitudinal vibration and lateral vibration are applied to the piezoelectric ceramic plate 21. Raised, the friction member 25 has been adapted to elliptical motion by the resultant force of these vibrations.

  Then, for example, PID calculation processing is performed in the drive control unit 18 according to the deviation between the position information from the position detecting means 16 accompanying the movement of the stage 13 and the reference position information based on the preset movement profile of the stage 13. Then, feedback control for outputting a command signal to the ultrasonic motor 20 is performed.

  It should be noted that the determination of the P term, I term, and D term, which are control parameters for performing the PID calculation, is carried out by experiments so that the position deviation and positioning accuracy during the movement of the stage 13 satisfy the standard before actual driving. It came to be decided by mistake.

  Further, in Patent Document 1, in a seal remaining life management device for a vibrator, the total result obtained by integrating the sliding amount is added to the total sliding amount so far, and the total sliding amount reaches a predetermined set value. It is shown to determine whether or not.

Furthermore, in the precision drive device using an ultrasonic motor as a drive source in Patent Document 2, the present inventors calculate the friction work amount of the friction member 25 and monitors the friction work amount, thereby monitoring the life of the friction member. It is shown that can be predicted.
JP 2003-139657 A JP 2003-339175 A

  However, when the precision driving device 10 is driven at a high speed for a long time, a crack occurs on a contact surface (hereinafter referred to as a driving surface) of the friction member 25 with the driving force transmission member 14.

  This is due to the fact that local heat generated on the driving surfaces of the friction member 25 and the driving force transmission member 14 causes stress differences at various locations on the driving surface due to differences in thermal expansion between the heat generating portion and the non-heat generating portion. This is thought to be due to two factors: material fatigue due to high-speed, long-time driving.

  Thus, if the driving surface of the friction member 25 is cracked, the driving surface may be slipped, and not only good driving cannot be maintained, but also the stage of the precision driving device 10 is suddenly moved during driving. When it has to be stopped, the friction member 25 is damaged from the crack as a starting point due to the stress applied to the drive surface due to the sudden stop, but there is a problem that the remaining life associated therewith cannot be predicted.

  In particular, as a means for managing the remaining life, there is a case where the total sliding amount is simply integrated as in Patent Document 1, but the influence of force variation is not taken into consideration.

  For this reason, the life setting for each device varies, and even if the load increases at an accelerated rate due to an unexpected factor, the remaining life cannot be predicted.

  In addition, in the monitoring of the frictional work amount described in Patent Document 2 already disclosed by the present inventors, the frictional wear amount of the friction member 25 of the ultrasonic motor can be predicted. Although it was possible to predict and determine the life due to wear, it was impossible to predict and determine the life due to material fatigue. It was difficult to manage and control.

In view of the above problems, the precision drive device of the present invention has the following configuration.

The precision drive device according to the present invention is based on a movable body that is movable by friction driving with a friction member of an ultrasonic motor , position detection means that measures the position of the movable body, and position information from the position detection means. comparing a drive control unit for outputting a driving command signal for driving the ultrasonic motor, and a friction specifications Kotoseki calculated amount and pre Me set threshold value of the friction member, it determines the life of the friction member A life determination unit. The friction work accumulated amount is an accumulated value of the friction work,
The friction work is calculated using the slip amount (S) of the friction member , the tangential force (F) , and the number of driving times f ′ between the servo loops .

In addition, the precision driving device of the present invention preferably has the following configuration.

Preferably, a friction member is joined to the tip of the ultrasonic motor, the friction member is brought into contact with the movable body, and the movable body is moved linearly.

Preferably, if the previous SL friction work integrated amount exceeds a predetermined threshold value, characterized by comprising a warning signal generator for issuing a warning.

Preferably, the preset threshold value is set to a region equal to or less than 4/5 of the total friction work when the drive surface of the friction member is cracked.

Preferably, there is provided a warning signal generation unit that issues a warning when the tangential force becomes twice the initial value.

Preferably, the friction member of the ultrasonic motor is made of any one of alumina, alumina titanium carbide, and alumina titanium nitride.

Preferably, the tip surface of the friction member is a spherical surface.

The driving method of the precision driving device of the present invention is as follows.

The driving method of the precision driving device of the present invention is a driving method of a precision driving device provided with a movable body movable by friction driving with a friction member of an ultrasonic motor , and a position detection step of detecting the position of the movable body If, based on the position information measured in the position detecting step, comparing the driving step of driving the ultrasonic motor, and a friction specifications Kotoseki calculated amount and pre Me set threshold value of the friction member, A determination step of determining a life of the friction member, wherein the friction work integrated amount is an integrated value of the friction work amount, and the friction work amount includes a slip amount (S) and a tangential force (F) of the friction member. ) And the number of driving times f ′ between servo loops .

  According to the configuration of the present invention, by comparing the integrated value of the work amount contributing to physical deterioration in the movable part of the device having the movable part with the integrated value of the work amount set to a predetermined value, Manage and control the operating status of moving parts, quickly detect the abnormal status and life of the equipment, and can take actions such as generating warnings and stopping the equipment, thereby causing malfunctions in the manufacturing process of various products. As a result, it is possible to minimize the occurrence of defective products due to, and productivity is improved.

  Further, in the present invention, by detecting the change of the force factor that is easily affected and fluctuated quickly by the operating state, and managing and controlling the operation of the apparatus, the mere deterioration of the movable part is achieved. In addition, it is possible to grasp changes in the operating state caused by deterioration.

  Further, in the present invention, the friction work integrated amount corresponding to the total friction force applied to the driving surface of the friction member 25 by driving the movable body is set so as to be a region where no cracks occur on the driving surface. By determining the driving life of the precision driving device 10 as a threshold value, slippage generated on the driving surface of the friction member 25 when a crack occurs is prevented, and furthermore, due to stress generated on the driving surface when the device is suddenly stopped. It is possible to prevent the friction member 25 from being damaged with a crack as a starting point.

  In addition, it is possible to predict the life of the device by driving the precision drive device 10 for a short time and calculating the friction work generated by one drive, so that It is possible to greatly reduce the number of troubleshooting and maintenance operations after installation of the apparatus, and it is possible to greatly reduce the cost required for the manufacturer's warranty for the precision drive device 10 such as troubleshooting and maintenance.

  Further, the life prediction by the life determination unit is more effective when the ultrasonic motor is brought into contact with the moving direction of the stage 13 which is a movable body in the vertical direction and the movable body is moved linearly.

  Further, by providing a warning signal generation unit that issues a warning when the tangential force becomes twice the initial value, it is possible to detect in advance that a crack is generated in the friction member 25 and perform maintenance of the apparatus. It is possible to keep the precision drive device 10 in a good operating state at all times.

  Furthermore, the material of the friction member 25 of the ultrasonic motor 20 is any one of alumina, alumina titanium carbide, and alumina titanium nitride, so that good driving can be maintained even if the precision driving device 10 is driven for a long time. It becomes possible. In particular, alumina titanium carbide and alumina titanium nitride have good mechanical properties such as hardness and toughness, have durability against stress generated by the difference in thermal expansion of the drive surface, or material fatigue, and for a long time. In this driving, cracks on the driving surface can be made difficult to occur.

  In addition, by making the tip of the friction member 25 of the ultrasonic motor 20 spherical, the friction member 25 is brought into contact with the driving force transmission member 14 of the stage 13 which is a movable body and positioned so as to be in contact with one another. Is unlikely to occur.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 shows an operation control flowchart in the operation apparatus of the present invention.

  As shown in FIG. 1, after starting the operation of the apparatus, the movable speed and acceleration of the movable part of the apparatus are calculated, and further, the amount of work performed by moving the movable part is calculated based on these values. Here, the work amount includes work performed by moving a movable part of the apparatus, work performed by a portion in contact with the movable part, or work of a power source for moving the movable part. Of the work of the entire apparatus movable part, the amount of work related to physical deterioration, that is, the life of the apparatus is shown. A typical example of this is friction work. The friction work indicates the amount of work caused by friction between the movable part and its contact part. It can be said that the work is accompanied by physical deterioration due to fatigue of the material used, that is, the work amount contributing to the physical deterioration.

  Then, after calculating the work amount contributing to the physical deterioration as described above, the work amount is integrated every time the number of movements of the movable portion reaches an arbitrary value, and the integrated value of the next work amount is (1). It is confirmed whether it is changing at an acceleration or (2) a predetermined value is not reached.

  If either or both of the conditions (1) and (2) are satisfied, a warning signal is generated so that a warning can be given to the device manager to notify the device abnormality and to operate the device. If it is not, the moving speed calculation, the work amount calculation, and the integration of the moving part are repeated.

  By operating the device with such a control method, it is possible to prevent a decrease in the productivity of the article manufacturing process in which the device is introduced when the operating state of the device changes significantly or stops due to its service life. It becomes.

  Note that, with regard to the work amount, the force factor included in the work amount calculation formula is particularly susceptible to the influence of the operating state and is likely to vary. In the present invention, by detecting this acceleration change in particular, it is possible to avoid operation troubles of the apparatus and prevent in advance that the production efficiency is lowered by affecting other processes in the article manufacturing process. It is.

  Next, an embodiment of the precision drive device of the present invention with friction work using the control method will be described in detail.

  FIG. 2 is a schematic view showing an example of the precision drive device of the present invention. The same parts as those in the conventional example are denoted by the same reference numerals.

  The precision driving device 1 of the present invention includes a pair of guide members 12 such as cross roller guides on a base board 11 and linearly guides a stage 13 as a movable body by these guide members 12. .

  A driving force transmission member 14 is installed on one side surface of the stage 13 in parallel with the guide member 12, and a linear scale 15 is installed on the other side surface of the stage 13 in parallel with the driving force transmission member 14. In addition, a measuring head 16 is provided at a position facing the linear scale 15 to constitute a position detecting means 17, and two ultrasonic motors 20 are installed at a position facing the driving force transmitting member 14. The friction member 25 of the sonic motor 20 is in contact with the contact surface of the driving force transmission member 14 perpendicularly.

  Note that the number of ultrasonic motors 20 shown in FIG. 2 may be one or more depending on the load applied to the ultrasonic motor 20 such as a stage load. In FIG. 2, two ultrasonic motors 20 are installed. Yes. The mounting structure is the same as the conventional structure shown in FIG. Further, the position detection means 17 may have a structure in which a reflection mirror is provided on the stage 13 and the position is detected by a laser side length meter.

  Then, position information such as time, displacement, speed, acceleration and the like from the position detection means 17 accompanying the movement of the stage 13 is sent to the drive control unit 18, and the movement profile of the stage 13 set in advance by the drive control unit 18. Closed-loop drive control that performs feedback control that, for example, performs PID calculation processing based on a deviation from reference position information (displacement, velocity, acceleration) based on the output and outputs the output value to the ultrasonic motor 20 as a drive command signal By performing the above, the stage 13 is moved along the guide member 12 by friction drive with the friction member 25 provided in the ultrasonic motor 20, and is positioned.

  The movement profile of the stage 13 indicates collective information obtained from the time to the target position of the stage 13, displacement, speed, acceleration, and the like.

  Next, a life determination unit 2 and a warning signal generation unit 3 are connected to the precision drive device 1 of the present invention shown in FIG. Hereinafter, the life determination unit 2 and the warning signal generation unit 3 will be described in detail.

  The life determination unit 2 refers to a position between the position detection unit 17 and the drive control unit 18 in order to prevent a crack from occurring on the drive surface of the friction member 25 of the ultrasonic motor 20 and maintain a good drive state. Installed.

The total integrated amount of the life determination part 2, friction work quantity generated by the friction driving of the friction member 25 and the driving force transmitting member 14 of the ultrasonic motor 20 (W), i.e. the friction Specification Kotoseki calculated amount (sigma Wf) for, obtains a region that does not crack the drive surface of the friction member 25 of the ultrasonic motor 20 is generated by experiment empirically friction specification Kotoseki calculated amount sigma Wf in this region is inputted set as a threshold . The friction work accumulated amount sigma Wf life determination unit said threshold and precision drive device 1, 2 is an integrating value of the friction work amount generated by the driving per unit time of the friction member 25 that is calculated every time the reciprocating When this value exceeds the threshold value, the friction member 25 is determined to have a lifetime.

Here, details of the friction specification Kotoseki calculated amount (sigma Wf) calculation method for. From the positional information such as time, displacement, speed, acceleration, etc. sent to the life determination unit 2, the number of ultrasonic motors 20 installed, the driving performance such as the driving frequency, and various conditions relating to the driving of the precision driving device 1 such as the stage load , slip of definitive to the number of driving frequency per unit time of the ultrasonic motor 20 (S), the tangential force (F) determined, further multiplied by the ultrasonic motor 2 driving number f between the servo loop 'on this product the by integrating the amount of friction work (W) to be calculated is Kotoseki calculated amount specification friction (sigma Wf), is expressed by the following equation (1) Te.

  In this equation 1, the slip amount S is expressed by S = (Vs−Vt) × where Vs is the driving speed of the stage 13, Vt is the driving speed of the ultrasonic motor, Tc is the contact time of the driving force transmission member 14 and the friction member 25. Tc and the tangential force F are calculated by F = ma, where a is the acceleration of the stage 13 and m is the weight of the stage 13, respectively.

Further, f ′ in the equation 1 is a value obtained by t × f, where t is the time between servo loops and f is the drive frequency of the ultrasonic motor 20, that is, the number of times the ultrasonic motor 20 is driven between servo loops. Represents. Then, it is of the friction work integrated amount sigma Wf by integration of figures from these drive start up drive-end (end) is obtained.

Incidentally, when the number of installed machines of the ultrasonic motor 20 is equal to or greater than two aircraft is life by comparison with a value obtained by dividing the said threshold the friction work integrated amount sigma Wf obtained in equation (1) with installation unit number Make a decision.

  In addition, the threshold value of the friction work integration amount is determined by driving the precision drive device of the present invention by closed loop drive control, confirming cracks in the drive surface of the ceramic friction member 25 and changes in the drive state. With respect to the total friction work obtained by integrating the friction work, an area of 4/5 or less, that is, a 20% margin, is set, and the remaining 80% is set in the safety area. Here, as a reason for seeing the safety of 20% as described above, the precision driving device 1 of the present invention can control the position of nano-micron order, and when this is used for a semiconductor manufacturing process or the like, a little position is required. This is because variations in accuracy affect the product yield, and it is necessary to set the threshold value in a region where the driving state does not change.

  Further, as shown in FIG. 2, the precision driving device of the present invention brings the friction member 25 of the ultrasonic motor 20 into contact with the moving direction of the stage 13, which is a movable body, so that the movable body is linearly moved. This is particularly effective when moving. That is, most of the precision drive devices with linear drive are large-sized, and many devices are often operated at the same time in the manufacturing process of semiconductors and the like, and the drive state of the precision drive device 1 affects the product yield. Therefore, it can be said that it is particularly useful to provide the life determination unit 2 and the warning generation unit 3 that serve as one standard for this change.

  Further, in FIG. 3, alumina is used as the friction member 25 of the ultrasonic motor 20, and when the friction work integrated amount ΣWf when driven at a driving speed of 100 mm / s is plotted on the vertical axis, the number of times of driving the precision driving device 1 (= super A graph with the horizontal axis representing the number of times the sonic motor 20 is driven) is shown. In the precision driving device 1 used for the test, when driven at 100 mm / s, the frictional work amount performed by one driving is about 1.8 mJ, and when it is driven 100,000 times, the frictional work integrated amount is about The friction work integrated amount ΣWf increases as the number of times of driving increases as 180J. In a drive test in which closed-loop drive control is performed in advance with the same apparatus and condition settings, if the boundary line A in the figure is exceeded, a crack occurs on the drive surface of the friction member 25 of the ultrasonic motor 20, and then the drive is continued. It was confirmed that the amount of friction work increased due to the influence of the cracks on the drive surface.

  In the present invention, depending on the driving conditions of the precision driving device 1 and the material of the friction member 25 of the ultrasonic motor 20 that is the driving source, the stable region below the boundary line A according to the conditions of each precision driving device 1. The friction work integrated amount ΣWf is determined within the threshold value, and if this value is exceeded, it is determined that the friction member 25 of the ultrasonic motor 20 has a life due to a crack on its drive surface. In FIG. 3, point B in the figure is set as a threshold value of the friction work integration amount ΣWf, and when this value is exceeded, the friction member 25 is determined to have a lifetime.

  Furthermore, the warning signal generator 3 that issues a warning when the friction work integrated amount ΣWf, which is the life limit condition of the life determination unit, exceeds a set threshold value will be described.

  This warning signal generation unit 3 is installed between the life determination unit 2 and the drive control unit 18, and the friction work integrated amount Wf exceeds the threshold value in the life determination unit 2 and the friction member 25 of the ultrasonic motor 20. Is installed in order to issue a warning signal to the administrator of the precision drive device 1 and to inform it of it. In most cases, the precision drive device 1 is driven by automatic control and is managed by a computer. Therefore, if an abnormality occurs in the driving state, if it is not promptly transmitted to the manager, for example, the entire semiconductor manufacturing process in which the precision driving device 1 is introduced will be affected, resulting in a significant reduction in production efficiency. Invite.

  In particular, the warning should be issued when the tangential force (F), which is a factor of the force, of the friction work integrated amount Wf has doubled. This is because the tangential force is calculated by the product of the stage load m that does not change and the acceleration a that more significantly represents the operating state of the apparatus. If the tangential force is doubled, the acceleration of the apparatus is doubled. This is because it is clear that a serious change has occurred in the operating state.

  The warning signal generator 3 includes a commonly used patrol lamp, a buzzer that emits a warning sound, and the like. When the life determining unit 2 determines that the life is long, the life determining unit 2 Any configuration may be adopted as long as it can transmit an abnormality to the visual and auditory senses of the device manager by sending a signal.

  In addition, the ceramic friction member 25 of the ultrasonic motor 20 used in the precision driving device 1 of the present invention is preferably made of any one of alumina, alumina titanium carbide, and alumina titanium nitride. .

  The alumina is generally used in various applications, is inexpensive in comparison with other materials in terms of cost, and also when used as the friction member 25 of the ultrasonic motor 20, The drive surface is not easily cracked and has excellent durability.

Furthermore, there is alumina titanium carbide as a material exhibiting durability superior to that of the alumina. This alumina titanium carbide is a composite material of alumina and titanium carbide, and has high hardness and high melting point (Vickers hardness (Hv): 18 GPa, melting point 2100 ° C.) and higher hardness and high melting point. In addition, since the composite material contains titanium carbide having high toughness (Vickers hardness (H _V ): 28 GPa, melting point: 3200 ° C., fracture toughness value: 6 MPam ^1/2 ), it has better mechanical properties than alumina. In addition, the friction member 25 has durability against the stress generated by the difference in thermal expansion on the driving surface. Furthermore, since the graining and cracks on the drive surface are less likely to occur, the frictional wear of the friction member 25 and the driving force transmission member 14 that is the counterpart material can be reduced, and the precision drive device 1 can be driven stably over a long period of time. It becomes possible to make it.

  Here, the content of titanium carbide in the alumina titanium carbide forming the friction member 25 is preferably 10 to 50% by mass. This is because if the content of titanium carbide is less than 10% by mass, it is difficult to improve mechanical properties such as hardness, strength, and toughness, and slipping when the ultrasonic motor 20 is driven at high speed is prevented. On the contrary, if the content of titanium carbide exceeds 50% by mass, the content of titanium carbide, which tends to decrease the hardness when exposed to high temperatures, becomes too large. This is because, when the friction drive with the transmission member 14 takes a long time, wear of the friction member 5 proceeds.

  The alumina titanium carbide contains oxides such as Mg, Zr, Si, and Y as auxiliary components such as a sintering aid in addition to alumina and titanium carbide, but Mg, Zr, Si, Y Is a paramagnetic metal, so that if the content of this oxide is too high, it becomes magnetic, and if the content of the paramagnetic metal oxide exceeds 7% by mass, the maximum magnetic flux density is 0.05 μT. Therefore, it cannot be used for precision drive devices such as an electron beam exposure device, which dislike magnetic materials. Therefore, when the content of the paramagnetic metal oxide to be contained as an auxiliary component is less than 0.1% by mass, it becomes difficult to obtain a sintered body.

  Therefore, the content of the paramagnetic metal oxide contained as an auxiliary component may be 0.1 to 7% by mass, and if contained within this range, the maximum magnetic flux density is 0.05 μT or less and the hardness is increased. be able to. The balance is mainly composed of alumina and titanium carbide, but the alumina, titanium carbide, and sintering aid may be mixed in trace amounts as long as they are inevitable impurities such as those contained in paramagnetic metal oxides. .

  The maximum particle diameters of the alumina crystal and the titanium carbide crystal in the sintered body of the composite material are preferably 4 μm or less, and the maximum pore diameter of the sintered body of the composite material is preferably 2 μm or less.

  Further, an alumina titanium nitride having mechanical properties equivalent to those of the alumina titanium carbide can be suitably used as the friction member 25 of the ultrasonic motor 20. These alumina titanium carbide and alumina titanium nitride are more expensive than alumina in terms of production cost and have less cost advantage, but they are superior in durability and equivalent to alumina in terms of cost when considered as a total. It can be said that there is.

  Moreover, in the friction member 25 of the ultrasonic motor, it is more preferable that the shape of the tip portion is a spherical surface. If the tip is not spherical, depending on the positioning accuracy when the ultrasonic motor 20 is positioned and fixed, it may be fixed to the surface of the driving force transmission member 14 of the stage 13 in such a way that it is fixed. In such a state, it becomes impossible to drive the fine precision driving device 1 well. A spherical surface with a radius of curvature of 100 mm or less is preferable.

  The embodiment of the present invention has been described above, but the present invention is not limited to application to a linear drive system, and can be suitably used for a rotary drive system. Various modifications are possible without departing from the scope of the present invention. Needless to say, the present invention can be applied to improvements and modifications.

  Examples of the present invention are shown below.

  The life determination unit 2 is manufactured by manufacturing the precision drive device 1 shown in FIG. 2 and driving it for a long time to calculate the friction work integration amount ΣWf and comparing it with a threshold value of the friction work integration amount obtained by conducting a test in advance. Thus, an experiment for determining the life of the friction member 25 of the ultrasonic motor 20 was performed.

  In the precision drive device 1 used in the experiment, a cross roller guide having a stroke of 200 mm is used as the guide member 12 for guiding the stage 13, and the stage 13 is a plate-like body of 250 mm × 120 mm × 30 mm, and the material thereof is aluminum. It is formed by.

  The ultrasonic motor 20 for driving the stage 13 includes a friction member 25 made of alumina ceramics on the end face of the piezoelectric drive unit 24 having a width of 8 mm, a length of 30 mm, and a thickness of 3 mm. 4 electrode films 22a, 22b, 22c and 22d are formed, 22a and 22d located diagonally, 22b and 22c are connected to each other, and one common electrode film is formed over the other main surface. In other words, the frictional member 25 is elliptically moved by applying a command voltage having a phase difference of 90 degrees to the four electrode films. The friction drive surface of the friction member 25 was a spherical surface with a radius of curvature of 3 mm, and the surface roughness was 0.2 μm in terms of centerline average roughness (Ra).

  Further, the linear scale constituting the position detection means 17 of the stage 13 is a Mitutoyo linear scale S33C, which is installed on one side of the stage 53 and the measuring head 16 is installed at a position facing the linear scale. Thus, the position detection means 17 was configured, and a driving force transmission member 14 made of alumina ceramics was installed on the other side surface of the stage 13. The driving surface of the driving force transmitting member has a surface roughness of center line average roughness (Ra) of 0.2 μm.

  A life determination unit 2 to which a threshold value of the friction work integration amount is input is installed between the position detection unit 17 and the drive control unit 18, and the life determination unit 2 further includes a friction work integration amount ΣWf between servo loops. Is connected to a warning signal generator 3 composed of a warning buzzer wired so that a buzzer will sound when the threshold value exceeds the threshold value.

  The life determination unit is driven by a precision drive device having the same specifications at a speed of 100 mm / s by closed loop drive control, and the drive surface of the alumina ceramic friction member 25 is cracked, and the drive state is also For points where positioning accuracy of ± 1 μm cannot be maintained, the remaining 80% except for 20%, that is, a threshold value 400J (joules) of frictional work accumulated amount obtained in advance is empirically entered and tested. is doing.

  As a result of the driving test, it was confirmed that a warning buzzer sounded immediately after the value of the cumulative amount of friction work in the precision driving device 1 of the present invention exceeded 400J. Further, when the driving surface of the ceramic friction member 25 was confirmed with a metal microscope after the test, it was confirmed that a crack had occurred and that the target positioning accuracy deviated from ± 1 μm in the driving state.

  Next, the test which drives an apparatus on the same conditions as the material of the friction part seat 25 of the ultrasonic motor 20 of the precision drive apparatus 1 of this invention used in Example 1 by the alumina titanium carbide was implemented.

  As a result, in the alumina titanium carbide, the total friction work is 10 times or more that of the alumina of the first embodiment, and the threshold value to be input and set in the life determination unit 2 is also set to a value 4 kJ that is ten times or more of the first embodiment. It was confirmed that a good driving state can be maintained for a longer time.

  Also, the same results as alumina titanium carbide can be obtained for alumina titanium nitride, and if applied as the friction member 25 of the ultrasonic motor 20 of the precision driving device of the present invention, a very good driving state can be maintained for a long time. Confirmed that you can.

The flowchart of the control method of the operating device of this invention is shown. It is the schematic which shows an example of the precision drive device of this invention. 5 is a graph showing an example of a relationship between an accumulated friction work amount ΣWf and the number of driving times when alumina is used as a friction member of an ultrasonic motor in the precision driving device of the present invention. It is the schematic which shows an example of the conventional precision drive device. It is the schematic which shows the internal structure of an ultrasonic motor.

Explanation of symbols

1, 10: Precision drive device
2: Life determination unit 3: Warning signal generation unit 11: Base board 12: Guide member 13: Stage 14: Driving force transmission member 15: Linear scale 16: Measuring head 17: Position detection means 18: Drive control unit 20: Ultrasonic Motor 21: Piezoelectric ceramic plates 22a, 22b, 22c, 22d, 23: Electrode film 24: Vibrating body 25: Friction member

Claims (8)

A movable body that is movable by friction driving with a friction member of the ultrasonic motor , a position detection unit that measures the position of the movable body, and a drive unit that drives the ultrasonic motor based on position information from the position detection unit precision of a drive control unit for outputting a command signal, comparing the friction specifications Kotoseki calculated amount and pre Me set threshold value of the friction member, and a determining life determination part life of the friction member A driving device comprising:
The friction work integrated amount is an integrated value of the friction work,
The precision work device in which the friction work is calculated using the slip amount (S) of the friction member , the tangential force (F) , and the number of driving times f ′ between servo loops .   2. The precision driving device according to claim 1, wherein a friction member is joined to a tip portion of the ultrasonic motor, the friction member is brought into contact with the movable body, and the movable body is moved linearly. If the previous SL friction work integration amount exceeds the preset threshold, precision drive system according to claim 1 or 2, further comprising a warning signal generator for issuing a warning. 4. The precision drive according to claim 3 , wherein the preset threshold value is set to a region of 4/5 or less of the total friction work when the drive surface of the friction member is cracked. apparatus. The precision drive device according to any one of claims 1 to 4, further comprising a warning signal generation unit that issues a warning when the tangential force is twice as large as an initial value. The precision drive system according to any one friction member of the ultrasonic motor is alumina, alumina titanium carbide, of claims 1 to 5 characterized in that it consists of any one of alumina titanium nitride. Precision drive system according to any one of claims 1 to 6, characterized in that the spherical distal end surface of the friction member. A driving method of a precision driving device provided with a movable body movable by friction driving with a friction member of an ultrasonic motor,
A position detecting step for detecting the position of the movable body;
A driving step of driving the ultrasonic motor based on the position information measured in the position detecting step;
It said friction Friction specification compares the Kotoseki calculated amount and pre Me set threshold value of the member, and a determination step of determining the life of the friction member,
The friction work integrated amount is the accumulated value of the friction work load,
The driving method in which the friction work is calculated using a slip amount (S) of the friction member , a tangential force (F), and the number of driving times f ′ between servo loops .

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