KR101223548B1 - Universal testing machine, linear actuator and torsion testing machine - Google Patents

Abstract

In the universal testing apparatus and the electric linear actuator which drive the crosshead by the servomotor and the feed screw mechanism, the linear guides of the servomotor and the feed screw mechanism are fixed to a single support plate. Preferably, the coupling connecting the drive shaft and the feed screw of the servomotor is a rigid coupling or a semi rigid coupling. Moreover, in the torsion test apparatus which applies a torsional load to a test piece by a servomotor and a deceleration mechanism, both a servomotor and a deceleration mechanism are fixed to the 1st support member which is a single member. Preferably, the coupling connecting the drive shaft of the servomotor and the input shaft of the deceleration mechanism is a rigid coupling or a semi rigid coupling.

Drive shaft, servo motor, feed screw, coupling, nut, linear guide, cross head, support plate, universal testing device.

Description

Universal test device, linear actuator, and torsion test device {UNIVERSAL TESTING MACHINE, LINEAR ACTUATOR AND TORSION TESTING MACHINE}

TECHNICAL FIELD This invention relates to a universal testing apparatus, the electric linear actuator suitable for this universal testing apparatus, and a torsion testing apparatus.

Conventionally, in order to evaluate the strength, rigidity, etc. of a material or a structure, the material test apparatus which applies tension, compression, and / or a bending stress to a material etc. is used. Such a material testing apparatus is generally called a universal testing apparatus. As a universal testing apparatus, there exist the apparatus of Unexamined-Japanese-Patent No. 2003-106965 and Unexamined-Japanese-Patent No. 2003-90786 (both Japanese Unexamined Patent Publication), for example.

The universal testing apparatus described in Japanese Patent Laid-Open No. 2003-106965 or Japanese Patent Laid-Open No. 2003-90786 includes a fixed part fixed to an apparatus frame, a crosshead configured to move in a predetermined direction (for example, up and down direction) with respect to the apparatus frame, It has a drive means for moving this cross head. A tensile test is performed by fixing one end of a test piece to a fixed part, the other end to a cross head, and driving a cross head away from a fixed part. Moreover, a compression test is performed by driving a crosshead to a fixed part in the state in which the test piece was fitted to the crosshead and the fixed part. The bending test is performed by, for example, supporting the test piece two points on one side of the fixed part or the crosshead, supporting the test piece one point on the other side, and driving the crosshead to approach the fixed part (three-point bend test). ).

Examples of the driving means for driving the crosshead of the universal testing apparatus include an electric linear actuator such as that described in Japanese Patent Laid-Open No. 2003-106965, a hydraulic linear actuator such as that described in Japanese Patent Laid-Open No. 2003-90786, and the like. The test apparatus using the hydraulic linear actuator is configured to drive a cylinder connected to the crosshead by means of sending high pressure hydraulic oil to the cylinder using a pump, or means for removing hydraulic oil from the cylinder. In this way, since the hydraulic linear actuator drives the crosshead directly by the hydraulic cylinder, the response delay is small, it is easy to vibrate the crosshead with a high frequency and a desired vibration waveform, and the fatigue test can be performed in a short time. On the other hand, the use of a test apparatus using a hydraulic linear actuator may result in the occurrence of environmental pollution due to leakage of oil or oil mist, enlargement of equipment by installing a hydraulic oil tank, and running caused by regular maintenance of the actuator or replacement of hydraulic oil. There are problems such as increased costs, large consumption of natural resources, and noise of pumps.

As the electric linear actuator, one adopting a feed screw mechanism as described in Japanese Patent Laid-Open No. 2003-106965 is used. Since the feed screw mechanism can withstand large loads and easily move the driving object precisely, it is a universal testing device in comparison with other types of electric actuators (which employ a linear motor or a rack-pinion mechanism). Can be said to be suitable.

The test apparatus using the electric linear actuator of the above-mentioned feed screw drive mechanism can drive a crosshead only by an electric servomotor and a feed screw mechanism, and therefore, a test apparatus using a hydraulic actuator that requires a hydraulic oil tank or a large pump. In comparison with the above, it can be said to be excellent in terms of load on the environment around the apparatus, running cost, and miniaturization of the test apparatus.

In addition, in order to evaluate the strength, rigidity, etc. around the predetermined axis of an elongate member, a torsion test apparatus is used instead of the universal testing apparatus. A torsion test apparatus supports a test piece at both ends, and applies a torque around a support shaft to one end to twist the test piece. As such a torsion test apparatus, there exists the apparatus of Unexamined-Japanese-Patent No. 10-274609, for example.

In the torsion test apparatus described in Japanese Patent Laid-Open No. Hei 10-274609, a frame is fixed to a base, and a pair of supporting members (plate-shaped members extending in the vertical direction) are provided on the horizontal surface of the frame. A chuck for holding the test piece at both ends is attached to each support member. The chuck attached to one support member is connected to the drive shaft of the servomotor through the reduction mechanism and the coupling. The chuck attached to the other supporting member is integrated with the supporting member, and is fixed to the other supporting member by holding one end of the test piece. Therefore, by driving the servomotor, the test piece held by the chuck can be twisted.

In general, the servomotor is low torque and is suitable for rotating the drive shaft at high speed. On the other hand, in the torsion test apparatus, it is desired to twist the test piece at a high torque and relatively low speed. For this reason, in the torsion test apparatus using the servomotor, a reduction mechanism such as a worm gear is provided between the drive shaft and the chuck of the servomotor to enable a high torque torsion test using the servomotor.

A fatigue test is mentioned as an example of the test generally performed using said universal testing apparatus and a torsion testing apparatus. A fatigue test is to apply a cyclic load (deformation) to a test piece and to measure the number of cycles until the test piece breaks. In such a fatigue test, it is preferable to make as many cycles of the repetitive load per unit time as possible so that the test can be completed in a short time.

(Initiation of invention)

As described above, the universal testing apparatus using the feed screw mechanism needs to connect the drive shaft and the feed screw of the servomotor. Similarly, the torsion test apparatus needs to connect the drive shaft of the servomotor and the input shaft of the deceleration mechanism. In general, in order to connect the input shaft of the feed screw or the deceleration mechanism and the drive shaft of the servomotor, it is necessary to accurately position (dwell) two axes to be connected. However, if it is manufactured with normal processing and assembly precision (for example, the error of about 100 micrometers), the axial deviation (eccentricity and declination) of the servo motor will be insignificant between a drive shaft and a feed screw. For this reason, when both shafts are connected by the rigid coupling formed of the material with high rigidity, big bending stress will generate | occur | produce in a shaft, and an input shaft of a feed screw or a deceleration mechanism cannot be rotated smoothly. Therefore, in the conventional universal testing apparatus or the torsion testing apparatus, the input shaft of the feed screw or the reduction mechanism and the drive shaft of the servomotor are connected by a flexible coupling capable of absorbing bending stress due to shaft displacement. The flexible coupling is a flexible shaft joint means that the elastic body can alleviate the above-described bending stress, so that the rotational torque of the drive shaft (drive shaft of the servo motor) can be smoothly transmitted to the driven shaft (feed screw).

As described above, since the flexible coupling is a coupling for transmitting torque through the elastic body, not only the bending stress but also the torque is absorbed to some extent. In the case of using a coupling in which the rigidity of the torsional direction is not so high as in the flexible coupling, when the input shaft (rotation shaft of the servo motor) is reciprocally rotated at a high cycle, the coupling cannot follow the movement of the input shaft. The amplitude becomes small. For this reason, when the input shaft and the output shaft were connected by flexible coupling, the output shaft could not be reciprocated in a high cycle.

As described above, in the universal testing apparatus for reciprocating the cross head by the electric servomotor and the feed screw mechanism, the repeated load could not be accurately applied to the test piece at a high cycle. For this reason, conventionally, the fatigue test could not be performed in a short time by the universal testing apparatus using a feed screw mechanism, and the universal testing apparatus using the hydraulic drive mechanism was forced to use for such use. Similarly, the torsion test apparatus for connecting one end of the test piece to the servomotor via the speed reducer could not perform the fatigue test in a short time.

The present invention has been made to solve the above problem. That is, the present invention is applicable to universal testing apparatuses, torsional testing apparatuses, and such universal testing apparatuses, which are capable of assembling with high precision and can apply a load to the test piece at high repetition speed by using a coupling with high rigidity. It is an object to provide an electric actuator.

In order to solve the said problem, the universal testing apparatus and the electric actuator of this invention fix the servomotor and a linear guide to a support plate. As a result, the servomotor and the linear guide are directly attached to the support plate on the basis of the support plate, so that it is easy to position each member with a relatively high precision and maintain high positional accuracy.

In addition, the torsion test apparatus of the present invention is fixed to a frame fixed to the base of the apparatus, a servo motor, a deceleration mechanism, an input shaft of the deceleration mechanism and a drive shaft of the servomotor, and a fixed output shaft of the deceleration mechanism. And a first gripping portion for holding one end of the test piece, a second gripping portion fixed to the frame and gripping the other end of the test piece, and a first supporting member fixed to the frame and to which the servomotor and the deceleration mechanism are fixed. As a result, the servomotor and the deceleration mechanism are assembled on the basis of the first support member, thereby making it easy to secure the accuracy of each member.

1 is a front view of a universal testing apparatus according to a first embodiment of the present invention.

It is a longitudinal cross-sectional view of the movable part of the universal testing apparatus which concerns on 1st Embodiment of this invention, and its periphery.

It is a longitudinal coupling of the rigid coupling of the universal testing apparatus which concerns on 1st Embodiment of this invention, and its periphery.

It is a longitudinal cross-sectional view of the vicinity of the through-hole of the table of the universal testing apparatus which concerns on 1st Embodiment of this invention.

5 is a cross-sectional view of the universal testing device according to the first embodiment of the present invention, in which a runner block and a rail are cut into one surface perpendicular to the major axis direction of the rail.

6 is a cross-sectional view taken along line II of FIG. 5.

7 is a block diagram of a control measurement unit of the universal testing apparatus according to the first embodiment of the present invention.

8 shows an example applied to a test apparatus having a linear actuator according to the first embodiment of the present invention.

It is a semi-rigid coupling of the universal testing apparatus of 2nd Embodiment of this invention, and its longitudinal cross-sectional view.

It is a front view of the torsion test apparatus by 3rd embodiment of this invention.

It is a top view of the torsion test apparatus by 3rd embodiment of this invention.

12 is a cross-sectional view taken along the line II-II of FIG. 11.

FIG. 13 is a cross-sectional view taken along III-III of FIG. 11.

It is a rigid coupling of the torsion test apparatus which concerns on 3rd embodiment of this invention, and its longitudinal cross-sectional view.

Fig. 15 is a block diagram of a control measurement unit of a torsion test apparatus according to a third embodiment of the present invention.

(Explanation of Symbols)

1 universal testing device 1 'test device with

10 Device frame section 12 Guide bar

20 Fixture 21 Upper Stage

22 Feed screw 25 Motor

28 Attachments 26 Gearbox

30 moving parts 31 lower stage

31a Ball Screw Nut 33 Table

34 Rigid Coupling 35 AC Servo Motor

36 Ball Screw 37 Motor Support Frame

40 linear guide 42 guide frame

44 Rail 46 Runner Block

130 Retaining ring 140 Retaining ring

150 Bearing section 151 Combination angular ball bearing

200 Control instrument 300 Semi-rigid coupling

500 Torsion Tester B Base

(Best Mode for Carrying Out the Invention)

EMBODIMENT OF THE INVENTION Below, embodiment of this invention is described in detail using drawing. 1 is a front view of a universal testing apparatus of a first embodiment of the present invention. As shown in FIG. 1, the test apparatus 1 according to the present embodiment includes an apparatus frame portion 10 fixed to a base B, an upper end of a test piece (or a jig attached to an upper part of a test piece), The fixed part 20 which abuts and the movable part 30 which abuts with the lower end (or the jig | tool attached to a lower part of a test piece) of a test piece are provided.

In the present embodiment, the device frame 10 extends from the upper end of each pair of leg portions 11 extending upwardly from the base B in a substantially vertical direction, and substantially upward from the upper end of each of the leg portions 11. It has a pair of guide bars 12 and the ceiling part 13 provided so that the upper end of both guide bars 12 may be connected.

The through hole 13a is provided in the substantially central portion of the ceiling 13. A feed screw 22 is inserted into the through hole 13a for moving the fixing portion 20 in the vertical direction. On the ceiling 13, a nut 23a engaged with the transfer screw 22 is provided. Reference numeral 24a denotes a radial ball bearing for rotatably supporting the nut 23a. Moreover, the outer ring of the radial ball bearing 24a is fitted in the bearing support part 24b fixed to the upper surface of the ceiling 13 by the bolt which is not shown in figure, and both are integrated. Similarly, the nut 23a is fitted to the inner ring of the radial ball bearing 24a, and both are integrated. For this reason, although the nut 23a becomes rotatable with respect to the bearing support part 24b, it cannot move to the up-down direction and the radial direction of the nut 23a. Therefore, when the nut 23a is rotated, the feed screw 22 engaged with the nut 23a moves in the vertical direction.

On the ceiling 13, the motor 25 for driving the nut 23a is arrange | positioned. The drive shaft 25a of the motor 25 is housed in the gearbox 26. The gearbox 26 is a member having a well-known gear mechanism for slowing down the rotation of the input shaft (the drive shaft 25a of the motor 25) and transmitting it to the output shaft 26a. As shown in FIG. 1, the output shaft of the gearbox 26 extends vertically downward from the bottom of the gearbox 26. That is, the gearbox 26 has a function of converting the rotational movement of the input shaft 25a extending in the horizontal direction into the rotational movement of the output shaft 26a extending in the vertical direction.

The drive pulley 26b is attached to the output shaft 26a of the gearbox 26. Moreover, the driven pulley 23b is attached to the nut 23a. An endless belt 27 is intersected with the drive pulley 26b and the driven pulley 23b, and the rotation of the drive pulley 26b is transmitted to the driven pulley 23b via the endless belt 27.

Therefore, by driving the motor 25 and rotating the drive shaft 25a of the motor 25, the nut 23a can be rotated and the feed screw 22 can be moved up and down.

At the lower end of the feed screw 22, the upper stage 21 of the fixing part 20 is suspended. Through-holes 21a extending in the vertical direction are formed at both left and right ends of the upper stage 21. The guide bar 12 is inserted through this through hole 21a. Therefore, the moving direction of the upper stage 21 is limited only to the up and down direction.

The bolt hole 21b which was perforated in the horizontal direction (direction toward the back surface from the surface in the figure) in the left-right direction (position outside of the through-hole 21a) in the figure of the upper stage 21 of the fixing | fixed part 20. Is formed. Although not shown in FIG. 1, a slot having an elongated hole shape extending from the side surface of the through hole yoke 21a to the outside in the left-right direction in the drawing of the upper stage 21 and orthogonal to the bolt hole 21b is formed in the upper stage ( 21). Therefore, when the bolt 21c is inserted into the bolt hole 21b and tightened, the diameter of the through hole 21a becomes small, and the inner circumferential surface of the through hole 21a clamps the guide bar 12. As a result, the upper stage 21 is fixed to the guide bar 12. In this state, when the bolt 21c is loosened, the upper stage 21 can be moved up and down by driving the motor 25.

The mechanism for vertically moving and fixing the upper stage 21 described above is used to adjust the span of the fixed portion 20 and the movable portion 30 according to the size of the test piece or the test method. In addition, during the test, the upper stage 21 is supported only by the guide bar 12, and the load by the test is hardly transmitted to the feed screw 22. As shown in FIG. For this reason, the strength of the feed screw 22, the nut 23a, the radial ball bearing 24a, the bearing support 24b, etc. should just be enough to support the weight of the upper stage 21 enough. If the pitch of the feed screw or nut is reduced, the feed screw can be driven with high precision, but the strength is reduced by that amount. However, in this embodiment, since the load which greatly exceeds the weight of the upper stage 21 is not applied to a feed screw or a nut, a feed screw and a nut with a small pitch are employ | adopted, and the fixed part 20 and a movable part are employ | adopted. The space | interval of 30 can be adjusted precisely.

Further, an attachment 28 such as a chuck for holding the test piece in the tensile test or a presser for pressing the test piece or the jig during the compression / bending test is attached to the lower part of the upper stage 21. The attachment 28 has a load cell built therein, so that the load applied to the test piece during the test can be measured. The load cell may be a member independent of the attachment, and the load cell may be attached to the lower part of the upper stage 21, and the attachment 28 may be attached to the lower part of the load cell.

Next, the structure of the movable part 30 is demonstrated. 2 is a vertical cross-sectional view of the movable portion 30 and its surroundings. On the leg part 11, the table 33 is fixed by welding. Specifically, the lower part of the side surface 33a of the table 33 is welded to the upper surface 11a of the leg portion 11, and the lower surface 33b and the leg portion 11 of the table 33 are formed. The inner side face 11b of) is welded. As a result, the table 33 is rigidly supported by the base B (FIG. 1) via the leg portion 11.

The table 33 is a steel plate with a sufficiently large dimension in the thickness direction, and can be regarded as a rigid body substantially with respect to the load applied to the movable portion 30 during the test. Under this table 33, the AC servomotor 35 is fixed via the motor support frame 37. As shown, a plurality of ribs 37a are formed on the sidewall of the motor support frame 37. The table 33 and the motor support frame 37 are integrated with high rigidity by electro-welding the upper end of the motor support frame 37 and the rib 37a and the lower surface of the table 33. The AC servomotor 35 is a high output AC servomotor capable of a high-speed inverted motion developed by the inventors. The AC servomotor 35 significantly reduces the inner inertia of the conventional AC servomotor, thereby increasing the drive shaft at a repetition rate of up to 500 Hz. Can reciprocate rotation.

Moreover, on the table 33, the lower stage 31 comprised so that it can move to an up-down direction by the AC servomotor 35 is arrange | positioned.

The feed screw mechanism is comprised by the lower stage 31, the ball screw 36 connected to the drive shaft 35a of the AC servomotor 35 via the rigid coupling 34, and the linear guide 40. As shown in FIG. The linear guide 40 is an element for guiding the movement direction of the lower stage 31 to be limited only in the up and down direction. The linear guide 40 has a guide frame 42, a pair of rails 44 and a runner block 46. The guide frame 42 is fixed to the upper surface 33c of the table 33 by bolts or the like. The guide frame 42 has a pair of side walls 42a extending in the vertical direction and an upper wall surface 42b connecting the side walls 42a with each other at the upper end, and are generally in an inverted U shape.

The rail 44 is a rail extending perpendicularly and is fixed to the inner surface of the side wall 42a. Moreover, one runner block 46 is fixed to each of the left and right ends of the lower stage 31, respectively, and each of them is engaged with the corresponding rail 44. Since the movement of the runner block 46 is guided by the rail 44, the moving direction of the lower stage 31 is limited only to the vertical direction.

The lower stage 31 is driven up and down by a ball screw mechanism. A ball screw nut 31a having a ball circulation function is filled in the lower stage 31. The ball screw nut 31a is engaged with the threaded portion 36a formed on the upper part of the ball screw 36. As described above, since the lower stage 31 is guided not to rotate around the ball screw 36 by the linear guide 40, when the ball screw 36 is rotated, the ball screw nut 31a is Move up and down. The lower stage 31 integrated with the ball screw nut 31a also moves in the vertical direction. Moreover, the opening part 42c is provided in the center part of the upper wall part 42b of the guide frame 42. As shown in FIG. The lower stage 31 penetrates through this opening part 42c, and the cross head 31b of the upper end is arrange | positioned above the upper wall part 42b. Therefore, the cross head 31b of the lower stage 30 and the attachment 28 attached to the upper stage 21 oppose. In the tensile test, the test piece is attached to the cross head 31b through the chuck. In the compression / bending test, a test piece or a jig is placed on the cross head 31b.

The lower part of the ball screw 36 is the shaft part 36b in which the groove | channel for engaging with the nut 31a is not formed. This shaft portion 36b is connected to the drive shaft 35a of the AC servomotor 35 via a rigid coupling 34. Although the detailed structure is mentioned later, the rigid coupling 34 which concerns on this embodiment has the torsional rigidity of the circumference | surroundings of the shaft part 36b of the ball screw 36 (namely, around the drive shaft 35a of the AC servomotor 35). Since it is comprised very high, the torque applied to the drive shaft 35a of the AC servomotor 35 can be transmitted to the ball screw 36 with high responsiveness.

Next, the structure of the rigid coupling 34 will be described. 3 is an enlarged cross-sectional view showing the rigid shaft coupling 34 and the drive shaft 35a of the AC servomotor 35 connected to each other via the rigid coupling 34 and the shaft portion 36b of the ball screw 36. to be.

As shown in the drawing, the cylindrical main body 34B of the rigid coupling 34 has a hollow, stepped round bar shape (ie, a stepped thick cylinder) as a whole. That is, the cylindrical main body 34B includes an upper cylindrical portion 34a having an upper opening 34c into which the shaft portion 36b of the ball screw 36 is fitted, and a drive shaft of the AC servomotor 35 ( 35a) has a lower cylindrical portion 34b having a lower opening 34d into which it is fitted. In this embodiment, since the shaft portion 36b of the ball screw 36 is smaller in diameter than the drive shaft 35a of the AC servomotor 35, the outer diameter of the upper cylindrical portion 34a is smaller than the outer diameter of the lower cylindrical portion 34b. It has a small diameter.

Moreover, the narrowing parts 34e and 34f are formed in the lower part of the upper cylindrical part 34a, and the upper part of the lower cylindrical part 34b, respectively. The diameters of the constriction portions 34e and 34f are approximately equal to the diameters of the shaft portion 36b of the ball screw 36 and the drive shaft 35a of the AC servomotor 35, respectively. For this reason, in the state in which the inner peripheral surface of the constriction part 34e and 34f, the shaft part 36b of the ball screw 36, and the outer periphery of the drive shaft 35a of the AC servomotor 35 have almost no clearance, The shaft portion 36b and the drive shaft 35a of the AC servomotor 35 are accommodated in the constriction portions 34e and 34f.

The diameter of the upper opening part 34c and the lower opening part 34d is larger than the outer diameter of the axial part 36b of the ball screw 36, and the drive shaft 35a of the AC servomotor 35, respectively. The fixing rings 130 and 140 are used to fix the upper opening 34c and the lower opening 34d to the shaft portion 36b of the ball screw 36 and the drive shaft 35a of the AC servomotor 35, respectively. do.

The fixing ring 130 has an inner ring 132, an outer ring 134, and a bolt 136. The outer circumferential surface 132a of the inner ring 132 is a tapered surface whose diameter decreases downward. In addition, the inner circumferential surface 132b of the inner ring 132 is a cylindrical surface that is slightly larger than the outer diameter of the shaft portion 36b of the ball screw 36. At the upper end of the inner ring 132, a flange portion 132c extending radially outward is formed. The flange portion 132c is provided with a plurality of bolt holes 132d through which the bolts 136 are inserted in the vertical direction. In addition, the inner circumferential surface 134a of the outer ring 134 is a tapered surface whose diameter decreases downward. The inner circumferential surface 134a of the outer ring 134 has the same taper angle as the inner circumferential surface 132b of the inner ring 132. The outer circumferential surface 134b of the outer ring 134 is a cylindrical surface that is slightly smaller than the diameter of the upper opening 34c. Moreover, the outer ring 134 is provided with the female screw 134c which engages with the bolt 136 in correspondence with the bolt hole 132d. Moreover, the diameter (maximum diameter) of the upper end of the inner peripheral surface 134a of the outer ring 134 is smaller than the diameter (maximum diameter) of the upper end of the inner peripheral surface 132b of the inner ring 132. For this reason, when the inner ring 132 is placed on the outer ring 134 so that the tapered surfaces are brought into contact with each other, the lower surface of the flange portion 132c of the inner ring 132 is floated without contacting the upper surface of the outer ring 134. Becomes The outer ring 134 and the inner ring 132 are inserted in the gap between the upper opening 34c and the shaft portion 36b of the ball screw 36, and the female screw 134c is passed through the bolt hole 132d of the flange portion 132c. When the bolts 136 inserted are tightened, the tapered surface 132b of the inner ring 132 receives the force of a suitable one in the radial direction from the tapered surface 134a of the outer ring 134, and the cylindrical surface of the inner ring 132 132b strongly presses the shaft portion 36b of the ball screw 36. At this time, the tapered surface 134a of the outer ring 134 receives radially outward force from the tapered surface 132b of the inner ring 132, and the cylindrical surface 134b strongly presses the upper opening 34c. By the resultant static frictional force, the shaft portion 36b of the ball screw 36 is firmly fixed to the upper cylindrical portion 34a of the cylindrical body 34B, and both are integrated. Further, in the drawing, two sets of bolts 136, bolt holes 132d, and female threads 134c are shown. In reality, a plurality of bolts 136 (for example, 10 are arranged on the circumference around the axis of the ball screw 36). Joe) installed.

Similarly, the fixing ring 140 has an inner ring 142, an outer ring 144, and a bolt 146. The outer circumferential surface 142a of the inner ring 142 is a tapered surface whose diameter decreases upward. The inner circumferential surface 142b of the inner ring 142 is a cylindrical surface that is a little larger than the outer diameter of the drive shaft 35a of the AC servomotor 35. The lower end of the inner ring 142 is formed with a flange portion 142c widening radially outward. The flange part 142c is provided with a plurality of bolt holes 142d through which the bolt 146 is inserted in the vertical direction. The inner circumferential surface 144a of the outer ring 144 is a tapered surface whose diameter decreases upward. The outer circumferential surface 144b of the outer ring 144 is a cylindrical surface that is slightly smaller than the diameter of the lower opening 34d. In addition, in the outer ring 144, a plurality of female threads 144c engaging with the bolt 146 are formed so as to correspond to the bolt holes 142d. Moreover, the diameter (maximum diameter) of the lower end of the inner peripheral surface 144a of the outer ring 144 is smaller than the diameter (maximum diameter) of the lower end of the inner peripheral surface 142b of the inner ring 142. For this reason, when inner ring 142 is arrange | positioned under outer ring 144 so that taper surfaces may contact each other, the upper surface of the flange part 142c of inner ring 142 will float without contacting the lower surface of outer ring 144. It is in a state. The outer ring 144 and the inner ring 142 are inserted into the gap between the lower opening 34d and the drive shaft 35a of the AC servomotor 35, and the female thread 144c is formed through the bolt hole 142d of the flange portion 142c. When the bolt 146 inserted into the rod is tightened, the tapered surface 142b of the inner ring 142 receives the radially inward force from the tapered surface 144a of the outer ring 144, and thus the cylindrical surface of the inner ring 142 142b strongly presses the drive shaft 35a of the AC servomotor 35. At this time, the tapered surface 144a of the outer ring 144 receives radially outward force from the tapered surface 142b of the inner ring 142, and the cylindrical surface 144b strongly presses the lower opening 34d. By the resultant static frictional force, the drive shaft 35a of the AC servomotor 35 is firmly fixed to the lower cylindrical portion 34b of the cylindrical main body 34B, and both are integrated. In addition, although the volt | bolt 146, the bolt hole 142d, and the female screw 144c are shown by 2 sets in the figure, in fact, the circumferential image centering on the rotation center axis of the drive shaft 35a of the AC servomotor 35 is shown. Many (for example, ten sets) are installed in the building.

The thickness of the upper cylindrical portion 34a and the lower cylindrical portion 34b of the cylindrical main body 34B is sufficiently large, whereby the torsional rigidity of the connection portion by the rigid coupling 34 is transferred to the feed screw 36 and AC. It becomes equal to or more than the drive shaft 35a of the servomotor 35. Therefore, the rigid coupling 34 can transmit the torque acting on the drive shaft 35a of the AC servomotor 35 to the ball screw 36 with high responsiveness.

As shown in FIG. 2, the through hole 33d is provided in the center of the table 33, and the ball screw 36 penetrates this through hole 33d. In this embodiment, in order to rotatably support the ball screw 36 which receives the heavy load of the thrust direction at the time of a test, the bearing part 150 is provided in the position of the through-hole 33d. Below, the structure of this bearing is demonstrated.

4 is a longitudinal cross-sectional view near the through hole 33d of the table 33. As shown in the drawing, a round annular first bearing attaching member 152 is fitted into the through hole 33d. On the upper end of the first bearing attachment member 152, a flange portion 152a is formed which is widened radially outward. The flange portion 152a is provided with a through hole 152b bored in the vertical direction. The female screw 33e is formed in the table 33 at the position corresponding to the through hole 152b. By inserting the bolt 158a into the through hole 152b and the female screw 33e, and then applying the bolt 158a, the first bearing attachment member 152 is fixed to the table 33, and both are integrated.

In addition, a step is provided between the screw portion 36a and the shaft portion 36b of the ball screw 36 such that the shaft portion 36b side has a small diameter. The 1st collar 154 is arrange | positioned at the part of this step | step. The combination angular ball bearing 151 and the second collar 155 are sequentially mounted below the first collar 154. Moreover, the male screw 36c is formed in the middle of the shaft part 36b of the ball screw 36, and the 1st collar 154, the combined angular ball bearing 151, and the 2nd collar 155 are the ball screw 36. As shown in FIG. Of the combination angular ball bearing 151 between the first collar 154 and the second collar 155 by attaching the nut 156 to the male screw 36c of the ball screw 36 after passing through the shaft portion 36b. ) Inner ring is supported.

In addition, a second bearing attachment member 153 is disposed below the first bearing attachment member 152. The second bearing attachment member 153 is fixed to the first bearing attachment member 152 by bolts 158b. The upper surface of the second bearing attachment member 153 is in contact with the outer ring of the combined angular ball bearing 151, and supports the outer ring of the combined angular ball bearing 151 from below.

The combined angular ball bearing 151 is a combination (front combination) which faces front surfaces of a pair of angular ball bearings 151a and 151b. In the present embodiment, the ball screw 36 receives a large load in the upward direction during the tensile test and in the downward direction during the compression / bending test. For this reason, a pair of angular ball bearings is combined by the front combination or the back combination (combined so that back may oppose each other), and it is set as the structure which can support the thrust load of both upper and lower directions. In particular, in the present embodiment, the combination angular ball bearing 151 of the front combination is adopted to prevent the stress concentration inside the bearing when the bending occurs in the shaft (the shaft portion 36b of the ball screw 36), thereby reducing the bearing itself. It is hard to be damaged.

In addition, in this embodiment, lubricating oil is supplied in order to reduce the friction of the ball of the combined angular ball bearing 151, and an inner and outer ring. In order to prevent the leakage of this lubricant, the clearance between the first collar 154 and the first bearing attachment member 152 and the clearance between the second collar 155 and the second bearing attachment member 153 are respectively. Oil seals 157a and 157b are provided. Moreover, in order to prevent the leakage of the lubricating oil from between the 1st bearing attachment member 152 and the 2nd bearing attachment member 154, it is packing between the 1st bearing attachment member 152 and the 2nd bearing attachment member 154. 159 is provided. Moreover, although the through-hole 153a which extends radially is formed in the 2nd bearing attachment member 153, this is used when supplying lubricating oil from the outside, and is normally clogged by the blind cap 153b.

Next, the structure of the rail 44 and the runner block 46 (FIG. 2) of the linear guide 40 which concerns on this embodiment is demonstrated in detail using drawing. FIG. 5: is sectional drawing which cut | disconnected the rail 44 and the runner block 46 to one surface (namely, a horizontal surface) perpendicular | vertical to the longitudinal direction of the rail 44, and FIG. 6 is sectional drawing I-I of FIG. As shown in FIGS. 5 and 6, the runner block 46 has a recess formed to surround the rail 44, and the recess has four grooves 46a extending in the axial direction of the rail 44. 46a ') is formed. A plurality of stainless steel balls 46b are housed in these grooves 46a and 46a '. The rails 44 are provided with grooves 44a and 44a 'at positions facing the grooves 46a and 46a' of the runner block 46, respectively, and the balls 46b are provided with the grooves 46a and 44a. Or between the groove 46a 'and the groove 44a'. The cross-sectional shapes of the grooves 46a, 46a ', 44a, 44a' are circular arc-shaped, and the radius of curvature is approximately equal to the radius of the ball 46b. For this reason, the ball 46b is in close contact with the grooves 46a, 46a ', 44a, 44a' without any remaining.

Inside the runner block 46, four ball retracting paths 46c and 46c ′ which are substantially parallel to each of the grooves 46a are provided. As shown in FIG. 6, the groove 46a and the retracting path 46c are connected to each other end via the U-curve 46d, and the groove 46a, the groove 44a, and the retracting path 46c. And U-curve 46d form a circulation path for circulating the ball 46b. The same circulation path is formed also by the groove 46a ', the groove 44a', and the retraction path 46c '.

For this reason, when the runner block 46 moves with respect to the rail 44, many balls 46b circulate through a circulation path, rolling the grooves 46a, 46a ', 44a, 44a'. For this reason, even if a large load is applied in a direction other than the rail axial direction, the runner block 46 can be supported by a large number of balls and the ball 46b is clouded so that the resistance in the rail axial direction is kept small. The rail 44 can be moved smoothly. In addition, the inner diameters of the retracting passage 46c and the U furnace 46d are slightly larger than the diameter of the ball 46b. For this reason, the frictional force generated between the retracting path 46c and the U furnace 46d and the ball 46b is extremely small, whereby circulation of the ball 46b is not disturbed.

As shown, the rows of two rows of balls 46b fitted into the grooves 46a and 44a form a front combination angular ball bearing with a contact angle of approximately ± 45 °. In this case, the contact angle is a line connecting the contact points of the grooves 46a and 44a with the ball 46b in the radial direction of the linear guide (the direction from the runner block toward the rail and downward in FIG. 5). It is an angle with respect to. The angular ball bearing thus formed has a direction perpendicular to both the reverse radial direction (in the direction from the rail to the runner block, upward in Fig. 5) and the transverse direction (the radial direction and the retraction direction of the runner block). Can support a load in the right and left directions at 5.

Similarly, the row of the two rows of balls 46b fitted into the grooves 46a 'and 44a' is connected to the contact points where the contact angles (the grooves 46a 'and 44a' contact the balls 46b are inverse to the linear guides). Angular ball bearings of the front combination type are formed such that the angle formed with respect to the radial direction is approximately + -45 degrees. This angular ball bearing can support the load in a radial direction and a transverse direction.

In addition, the row of two rows of balls 46b fitted into one of the grooves 46a and 44a (left side in the drawing) and one of the grooves 46a 'and 44a' (left side in the drawing) are also angular ball bearings of the front combination type. Form. Similarly, the row of two rows of balls 46b fitted into the other (right side in the drawing) of the grooves 46a and 44a and the other side (right side in the drawing) of the grooves 46a 'and 44a' also has a front-angle angular ball bearing. Form.

As described above, in the present embodiment, the front-side combined angular ball bearing having a large number of balls 46b is supported by loads acting on the radial direction, the reverse radial direction, and the transverse direction, respectively. It is possible to sufficiently support a large load applied in the direction of.

Next, the structure of the control measurement part of the universal test apparatus 1 which concerns on this embodiment is demonstrated. 7 is a block diagram of the control measurement unit 200 of the universal testing apparatus 1 according to the present embodiment. The universal testing apparatus 1 according to the present embodiment is capable of applying a repetitive load to the test piece at short intervals so that the fatigue test can be performed in a short time.

The control measuring unit 200 of the universal testing apparatus 1 includes a set value indicating unit 210, a drive control unit 220, and a measuring unit 250.

The set value indicating unit 210 is a unit for indicating how to move the lower stage 31 (FIG. 1). Specifically, it is a unit which outputs the displacement amount (target position) from the initial position of the lower stage 31 as a signal, and sends it to the drive control unit 220. The set value indicating unit 210 has an input interface 212 and a waveform generating circuit 214.

The input interface 212 is an interface for connecting the setting value indicating unit 210 and a workstation not shown. The operator of the universal testing apparatus 1 operates the workstation and instructs how to displace the lower stage 31. For example, if the static tension test is to be performed, the operator operates the workstation to input the displacement velocity to the lower stage 31 and transmits it to the input interface 212. In addition, when performing a fatigue test in which a cyclic load is applied to the test piece, the operator operates the workstation to input an amplitude, a frequency, and a waveform (which waveform of sine and triangle waves to use, etc.) of the lower stage 31. To the input interface 212. Instructions input to the input interface 212 are sent to the waveform generation circuit 214.

The waveform generation circuit 214 interprets the instruction transmitted from the input interface 212, sequentially calculates the displacement amount from the initial position of the lower stage 31, and transmits it to the drive control unit 220. When the fatigue test is performed, the lower stage (based on a function synthesized from a function having various amplitudes or frequencies is not limited to driving the lower stage 31 with a constant waveform and frequency such as a single sinusoidal or triangular wave). 31) is also possible. For example, it is also possible to drive the lower stage 31 so that the amplitude of the lower stage 31 changes over time based on a function of multiplying sinusoids of different frequencies.

The displacement amount of the lower stage 31 is output from the waveform generation circuit 214 as a digital signal. For this reason, the signal transmitted from the waveform generation circuit 214 to the drive control unit 220 is first input to the D / A converter 222 and converted into an analog signal. The displacement information of the lower stage 31 converted into the analog signal is then sent to the amplifier 224. The amplifier 224 amplifies and outputs displacement information of the lower stage 31 sent from the D / A converter 222.

As described above, in the present embodiment, various tests are performed by the AC servomotor 35 driving the lower stage 31. Here, the AC servomotor 35 incorporates an encoder for detecting the rotational speed of the drive shaft 35a (FIG. 1), and the rotational speed detected by the encoder is the current position calculation circuit of the drive control unit 220 ( 226).

The present position calculating circuit 226 calculates and outputs the present position of the lower stage 31 based on the detection result of the encoder of the AC servomotor 35. The difference between the output of the amplifier 224 and the output of the current position calculating circuit 226 (that is, a signal corresponding to the difference between the target position of the lower stage 31 and the current position) is supplied to the current generating circuit 228. Is sent.

The current generation circuit 228 generates a three-phase current output to the AC servomotor 35 based on the received signal, and outputs this to the AC servomotor. As a result, the AC servomotor 35 is driven so that the lower stage 31 reaches the target position.

The load applied to the test piece by driving the lower stage 31 is used to extract the deformation amount of the load cell 254 and the load cell 254 embedded in the attachment 28 (FIG. 1) of the universal testing apparatus 1 as an electric signal. Is detected by the bridge circuit 256. The detected load value is converted into a digital signal by the A / D converter 258 and transmitted to the workstation via the output interface 259. The work station aggregates the load values transmitted from the output interface 259, for example, generates and displays a graph with the horizontal axis as the time axis and the vertical axis as the stress applied to the test piece.

It is also possible to carry out so-called feedback control, which sends the load value output from the A / D converter 258 to the waveform generating circuit 214 and changes the behavior of the displacement of the lower stage 31 in accordance with the load. For example, when the displacement amount of the lower stage 31 and the load value do not show a proportional relationship, that is, when the test piece yields, the amplitude of the lower stage can be controlled, for example.

By using the universal testing apparatus 1 of the above structure, a static fracture test of a test piece, a fatigue test, etc. can be performed. Here, in this embodiment, the lower stage 31 is driven using the AC servomotor 35 of high responsiveness and high torque. For this reason, the universal testing apparatus 1 can apply the load of up to several 100 kN to a test piece, and can also apply a repetitive load to a test piece at a high frequency of several 100 Hz. Therefore, according to the universal testing apparatus 1 of this embodiment, it is possible to evaluate the fatigue characteristic of a test piece in a short time, and can shorten test time.

Moreover, according to the structure of this embodiment, as shown in FIG. 2, the rotation of the AC servomotor 35 which is a power source for moving the lower stage 31, and the drive shaft 35a of the AC servomotor 35 is carried out. The bearing 151 for the ball screw and the linear guide 40 used when converting the motion to the vertical motion are fixed to the table 33 which is the same plate. As a result, it is possible to accurately position and attach relative positions of the drive shaft 35a of the AC servomotor 35, the ball screw 36, the linear guide 40 for guiding the lower stage 31, and the like. Do. For this reason, high precision planting of the drive shaft 35a of the AC servomotor 35 and the shaft portion 36b of the ball screw 36 can be performed easily and more accurately. In addition, it is possible to stably maintain the relative position of each element positioned with high accuracy by arranging all elements that require high relative position accuracy on the same plate.

As described above, according to the configuration of the present embodiment, since the drive shaft 35a of the AC servomotor 35 and the ball screw 36 can be precisely precisiond, the AC servomotor 35 is driven by the deepening error. The bending stress acting on the drive shaft 35a or the shaft portion 36b of the ball screw 36 is relatively small. Usually, the coupling for connecting a servomotor and a feed screw uses the flexible coupling comprised so that a bending stress may be absorbed by interposing a low rigid material (rubber, a metal spring, etc.). However, in the present embodiment, as described above, since biaxial planting can be performed with high accuracy, the rigid coupling 34 formed of a material having high rigidity can be used. For this reason, the torque acting on the drive shaft 35a of the AC servomotor 35 can be transmitted to the shaft portion 36b of the ball screw 36 with high responsiveness. Therefore, even when the drive shaft 35a of the AC servomotor 35 is reciprocated at high cycles, since the ball screw 36 can accurately follow the movement of the drive shaft 35a, the test piece is of high rigidity such as steel, In addition, even when the crosshead 31b is reciprocated at a high speed of several 10 Hz or more, the set load (strain) can be accurately applied to the test piece. That is, the universal testing apparatus 1 according to the present embodiment can perform the fatigue test of the test piece in a short time.

In addition, in this embodiment, as shown in FIG. 2, although the rail 44 is set to the guide frame 42 and the runner block 46 is fixed to the lower stage, respectively, the runner block is guided to the guide frame, It is good also as a structure fixed respectively to a lower stage (namely, a nut which engages with a feed screw).

In addition, in this embodiment, although the linear actuator is used as a mechanism for vertically moving the crosshead of the universal testing apparatus, this linear actuator is not only the universal testing apparatus but also the vehicle C as shown in Fig. 8 in the vertical direction. Also available for excitation test apparatus 1 '. That is, four sets of linear motion actuators provided with the movable part 30 and the linear guide 40 (FIG. 1) which concerns on this embodiment are prepared, and each of them is equipped with the apparatus frame part 10 'supported by the base B. Fix it. The vehicle C can be excited by fixing each crosshead 31b to the wheel W of the automobile C to drive the AC servomotor 35 of the movable portion 30. Such an excitation test apparatus can excite a heavy subject such as an automobile C at a high vibration frequency.

In this embodiment, the rigid coupling 34 connects the shaft portion 36b of the ball screw 36 and the drive shaft 35a of the AC servomotor 35 (FIG. 3). However, this invention is not limited to said structure, You may use the other coupling which has high rigidity in a torsion direction. As such a coupling, for example, there is a semi-rigid coupling according to the second embodiment of the present invention described below.

The universal testing apparatus in which the ball screw and the drive shaft of the AC servomotor are connected by semi-rigid coupling will be described below as a second embodiment of the present invention. In addition, the coupling which connects a ball screw and the drive shaft of an AC servomotor differs in 1st Embodiment and 2nd Embodiment of this invention, and the others are the same. Therefore, in this embodiment, the same code | symbol as the thing of 1st Embodiment is attached | subjected to the member or element similar to 1st Embodiment, and the detailed description about them is abbreviate | omitted.

FIG. 9 shows the shaft portion of the drive shaft 35a and the ball screw 36 of the AC rigid motor 35 connected to each other via the semi-rigid coupling 300 according to the present embodiment. It is an expanded sectional view which shows 36b. The semi-rigid coupling 300 according to the present embodiment is configured so that the torsional rigidity is extremely high, and the torque applied to the drive shaft 35a of the AC servomotor 35 is highly responsive to the ball screw 36. Can be delivered. Moreover, it is comprised so that the displacement of the axis | shaft of a longitudinal direction may be absorbed flexibly by the internal resin member, and the vibration of the axial direction which the AC servomotor conveyed from the drive shaft 35a of the AC servomotor 35 generate | occur | produces is greatly reduced. It is difficult to transmit the ball screw 36.

As shown in FIG. 9, the semi-rigid coupling 300 includes an inner ring 360 made of nylon, a pair of outer rings 320 and 340 made of duralumin, and a plurality of fixing them (this embodiment). Is composed of six bolts 382. In the center of the inner ring 360, round holes 362a and 362b communicating with each other therein are provided coaxially. The inner diameter of the round hole 362a is such that the drive shaft 35a of the AC servomotor 35 can be inserted without a gap, and the inner diameter of the round hole 362b allows the shaft portion 36b of the ball screw 36 to have no gap. It is size to be able to insert. In addition, in this embodiment, since the shaft part 36b of the ball screw 36 is smaller than the drive shaft 35a of the AC servomotor 35, the outer diameter of the round hole 362b is larger than the outer diameter of the round hole 362a. It has a small diameter.

In the axial direction center of the inner ring 360, the flange part 360a which extends radially outward from the outer periphery of the inner ring 360 is formed. Tapered portions extending in the axial direction are formed from the central portions on both sides of the flange portion 360a, respectively. The outer surfaces 364 and 366 of the tapered portion are conical tapered surfaces whose outer diameter decreases closer to the axial tip. Further, through-holes having tapered inner surfaces 322 and 342 are formed in the center of the pair of outer rings 320 and 340 for fitting the inner ring 360. The outer ring 320 and 340 are arrange | positioned toward the inner ring 360 side in the direction which the taper surface of the inner surface 322, 342 spreads, respectively. The tapered inner surfaces 322, 342 of the outer rings 320, 340 have the same taper angles as the outer surfaces 364, 366 of the inner rings 360, respectively. In addition, the inner ring 322 of the outer ring 320 and the outer ring 364 of the inner ring 360, the inner ring 342 of the outer ring 340, and the outer ring 366 of the inner ring 360 overlap the outer ring. Tapered portions formed at both ends of the inner ring are fitted into the through holes of the 320 and 340.

In addition, a plurality of female screws 344 engaging with the male screw formed at the distal end portion of the bolt 382 are formed on the circumference around the axis of the through hole at equal intervals around the through hole of the outer ring 340. Further, bolt holes 324 and 368 are formed at positions corresponding to the female screw 344 in the flange portion 360a of the outer ring 320 and the inner ring 360, respectively. Six bolts 382 are inserted into the bolt holes 324 of the outer ring 320 and the bolt holes 368 of the inner ring 360 and engaged with the female screw 344 of the outer ring 340.

The front end of the drive shaft 35a of the AC servomotor 35 is inserted below the round hole 362a of the inner ring 360, and the front end of the shaft portion 36b of the ball screw 36 is inserted into the round hole 362b from above. Then, when the bolt 382 is tightened firmly, the inner ring 360 is strongly sandwiched between the outer ring 320 and the outer ring 340 from both sides, and the two of the inner ring 360 are inserted into the through holes of the outer rings 320 and 340. Taper portions are inserted deeply. For this reason, strong side pressure was applied to the drive shaft 35a of the AC servomotor 35 and the shaft portion 36b of the ball screw 36 from the round holes 362a and 362b of the inner ring 360 by the principle of the wedge. All. Therefore, a strong friction force is generated between the round holes 362a and 362b, the drive shaft 35a, and the shaft portion 36b of the ball screw 36, so that the drive shaft 35a and the ball screw 36 drive the inner ring 360. It is connected integrally through. As a result, the torsional rigidity of the connection part by the semi rigid coupling 300 becomes equal to or more than the feed shaft 36 and the drive shaft 35a of the AC servomotor 35.

As shown in FIG. 9, between the outer rings 320 and 340 is supported only by the inner ring formed from the nylon resin which is a viscoelastic body. In the semi-rigid coupling 300, the tip of the drive shaft 35a of the AC servomotor 35 and the tip of the shaft portion 36b of the ball screw 36 are minute (for example, about 1 millimeter). ) Are connected at intervals. Therefore, when a force in the direction compressing the shaft from the motor is applied, the inner ring 360 is elastically deformed, and the distance between the drive shaft 35a and the ball screw 36 is narrowed, so that the semi-rigid coupling 300 is in the semi-rigid coupling 300. The force in the axial direction can be absorbed, and the force transmitted to the ball screw 36 side can be greatly reduced. In this embodiment, the vibration attenuation rate of the inner ring 360 is substantially maximum in the natural frequency of the drive shaft 35a. Thereby, the vibration of the drive shaft 35a in the axial direction or the radial direction of the shaft can be effectively reduced.

On the other hand, as described above, the distance between the distal end of the drive shaft 35a of the AC servomotor 35 and the distal end of the shaft portion 36b of the ball screw 36 is as short as about 1 millimeter, and the distal end of each axis is entirely. The circumference is integrated with the inner ring. For this reason, it is fully rigidly connected in the torsion direction, and can transmit the rotational drive of the drive shaft 35a of the AC servomotor 35 to the ball screw 36 correctly.

The 1st and 2nd embodiment of this invention demonstrated above relates to the universal testing apparatus using a feed screw mechanism. However, the present invention can be used not only for the universal testing apparatus but also for other kinds of material testing apparatuses, such as the third embodiment of the present invention described below.

10 is a front view of a torsion test apparatus according to a third embodiment of the present invention. 11 is a top view of the torsion test apparatus according to the present embodiment. In the torsion test apparatus 501 according to the present embodiment, the elongated test piece S is held at both ends by the claws 572a and 574a of the chucks 572 and 574 so that the major axis direction thereof is substantially horizontal. The torsion test is to be done at. Incidentally, in order to clearly explain the structure of the torsion test apparatus 501, the test piece S and the chucks 572 and 574 for holding the test piece are shown only in FIG. That is, FIG. 11 is a top view of the twist test apparatus 501 in which the test piece S and the chucks 572 and 574 were separated.

As shown in FIG. 10, in this embodiment, the fixed end support part 520 for fixing and supporting the one end (fixed end) of the test piece S on the lower frame 510 fixed to the base B, and The drive end support part 530 which rotatably supports the other end (drive end) of the test piece S is provided. And by giving a predetermined torque about the rotation axis A to the test piece from the drive end support part 530, a torsional stress can be applied to the test piece S, and it can twist.

The fixed end support part 520 has the attachment flange 527 for attaching the fixed end side chuck 572 for holding the fixed end of the test piece S. As shown in FIG. The support shaft 526 extends substantially horizontally from the surface of the attachment flange 527 opposite to the surface to which the fixed end side chuck 572 is attached.

The tip of the support shaft 526 is connected to one end of the load cell 562 for torque measurement. Connection flanges are formed at the front end of the support shaft 526 and one end of the load cell 562, respectively, and the support shaft 526 and the load cell 562 are connected by fixing the flanges with bolts. The other end of the load cell 562 is fixed to the fixed end side side frame 522 of the fixed end support 520. The side frame 522 is firmly fixed on the fixed end support plate 521 of the fixed end support part 520 by means of bolt fixing, welding, or the like. The fixed end support plate 521 is fixed on the lower frame 510. Here, the side frame 522 is a plate-shaped member having an L-shaped cross-sectional shape, and ribs 522a for reinforcement are formed at the corners thereof. For this reason, the rigidity of the side frame 522 is high. Although details will be described later, since the fixed end support plate 521 is firmly fixed to the lower frame 510, the side frame 522 may be regarded as a rigid body integral with the base B.

Thus, the fixed end of the test piece S is fixed to the side frame 522 via the fixed end side chuck 572, the attachment flange 527, the support shaft 526, and the load cell 562. Here, the fixed end side chuck 572, the attachment flange 527, the support shaft 526, and the load cell 562 have sufficiently high torsional rigidity with respect to the test piece S, and torque to the drive end of the test piece S. By giving, torsional stress according to the magnitude of the torque can be generated inside the test piece (S). The magnitude of the torque applied to the test piece S is measured by the load cell 562.

In addition, the support shaft 526 is rotatably supported by the fixed end side bearing 524 in the middle. The fixed end side bearing 524 is also firmly fixed on the fixed end support plate 521 by means of bolt fixing, welding, or the like.

Next, a mechanism for fixing the fixed end support plate 521 to the lower frame 510 will be described. As shown in FIG. 11, a pair of grooves 511 are formed on the upper surface of the lower frame 510. Using the groove 511 and the bolt 512, the fixed end support plate 521 is fixed to the lower frame 510. In addition, the fixed end support plate 521 is provided with seven through holes 521a through which the bolt 512 is inserted through each groove 511 (that is, 14 in total), and these through holes 521a. By attaching the bolts 512 to all of the, the fixed end support plate 521 is firmly fixed to the lower frame 510.

Next, the structure of fixing the fixed end support plate 521 by the bolt 512 is demonstrated in detail. 12 is a cross-sectional view taken along the line II-II of FIG. 11. As shown in FIG. 12, the groove 511 is a stepped groove in which the width of the lower portion 511b is larger than the width of the upper portion 511a. The bolt 512 is a so-called hexagonal socket head bolt with a hexagonal hole 512a for a hexagon wrench formed in the head. The bolt 512 is engaged with the nut 513 disposed in the lower portion 511b of the groove 511. Since the dimension of the nut 513 is slightly smaller than the width of the groove 511b and larger than the width of the groove 511a, the fixed end support plate 521 and the groove are between the head of the bolt 512 and the nut 513. The upper part 511a of 511 is tightened firmly. As a result, the fixed end support plate 521 is firmly fixed to the lower frame 510.

Next, the structure of the drive end support part 530 is demonstrated.

As shown in FIG. 10, the drive end support 530 has an attachment flange 537 for attaching the drive end chuck 574 for holding the drive end of the test piece S. As shown in FIG. The reduction mechanism 536 is provided on the surface of the attachment flange 537 opposite to the surface on which the drive end side chuck 574 is attached. Specifically, the attachment flange 537 is formed in the output shaft of the reduction mechanism 536. The reduction mechanism 536 converts the rotational motion of the high speed and low torque of the input shaft into the rotational motion of the low speed and high torque of the output shaft. The rotational motion of the output shaft is transmitted to the drive end of the test piece S via the attachment flange 537 and the chuck 574.

This deceleration mechanism 536 is fixed to the drive end side frame 532 of the drive end support 530. The drive end side frame 532 is firmly fixed on the drive end support plate 531 of the drive end support 530 by welding. The drive end support plate 531 is fixed on the lower frame 510 by the same fixing means as the fixed end support plate 521. Here, the side frame 532 is a plate-shaped member that is substantially perpendicular to the rotation axis A, and reinforcing ribs 532a are formed at the corner portions formed by the side frame 532 and the drive end support plate 531. Is formed. This rib 532a is also welded to the drive end support plate 531 and the drive end side frame 532. Therefore, the side frame 532 and the drive end support plate 531 are integrated with high rigidity. As described above, since the drive end support plate 531 is firmly fixed to the lower frame 510, the side frame 532 may be regarded as a rigid body integral with the base B.

A cavity 514 is formed in the center portion (between the grooves 511 and 511) of the lower frame 510. The cavity 514 is provided with a feed screw mechanism for sliding the drive end support 530 in the direction of the rotation axis A with respect to the lower frame 510. As shown in FIGS. 10 and 11, in the cavity 514, a feed screw 544 extending in a direction parallel to the rotation axis A is provided. Both ends of the feed screw 544 are rotatably supported by a pair of bearings 545 and 546 (FIG. 10). In addition, a nut 548 engaging with the transfer screw 544 is fixed to the lower surface of the drive end support plate 531. For this reason, the feed screw 544 is rotated in the state in which the drive end support plate 531 is not fixed to the lower frame 510 (that is, the bolt for fixing the drive end support plate 531 is loosened). As a result, the driving end supporter 530 can be moved along the feed screw 544. At one end (bearing 545 side) of the feed screw 544, a handle 542 for rotating the feed screw 544 is provided. In this embodiment, the distance between the fixed end support part 520 and the drive end support part 530 can be adjusted according to the dimension of the test piece S by moving the drive end support part 530 in this way.

A pulley 538a of the encoder 538 is attached to the lower portion of the attachment flange 537 of the side frame 532. The outer circumferential portion 537a of the attachment flange 537 also has a function as a pulley, and the endless belt 539 extends across the pulley 538a of the encoder 538 and the pulley 537a of the attachment flange 537. By detecting the rotation angle of the pulley 538a, the encoder 538 calculates the rotation speed of the attachment flange 537, the rotation angle with respect to the initial position of the attachment flange 537, the number of cycles during the repeated test, and the like. This can be displayed on the display unit 538b of the encoder 538. Therefore, the operator of the torsion test apparatus 501 can confirm the progress of the torsion test or the like from the display contents of the display unit 538b of the encoder 538.

Next, the arrangement of the input shaft 536a of the deceleration mechanism 536 and the AC servomotor 535 that applies torque to the input shaft will be described. FIG. 13 is a cross-sectional view taken along III-III of FIG. 11. As shown in FIG. 13, the input shaft 536a of the deceleration mechanism 536 is connected to the drive shaft 535a of the AC servomotor 535 via a rigid coupling 533. Therefore, the torsional stress can be applied to the test piece S by driving the AC servomotor 535. As shown, the AC servomotor 535 is fixed to the side frame 532 via the motor support frame 534.

The deceleration mechanism 536 is filled in the opening 532b formed in the side frame 532 and is firmly fixed. In this embodiment, the reduction mechanism 536 is a wave gear reduction mechanism. The wave gear deceleration mechanism is characterized in that the input shaft and the output shaft are coaxial. For this reason, in this embodiment, the rotating shaft A and the drive shaft 535a of the AC servomotor 535 become coaxial. Since the rotating shaft A and the drive shaft 535a of the AC servomotor 535 become coaxial, the torsion test apparatus 501 becomes substantially symmetrical with respect to the vertical plane in which the rotating shaft A is included. For this reason, the test apparatus 501 has a good weight balance, and vibration is unlikely to occur during the test. Further, the wave gear deceleration mechanism has a feature that the backlash is extremely small. For this reason, by introducing a wave gear reducer into the fatigue test apparatus which applies a repetitive load to a test piece, it became possible to drastically improve the precision of a fatigue test. As far as the present inventors recognize, there is no use of a wave gear reducer in a conventional fatigue test apparatus.

The rigid coupling 533 according to the present embodiment is configured to have extremely high torsional rigidity, and the torque applied to the drive shaft 535a of the AC servomotor 535 has a high responsiveness and has an input shaft of the reduction mechanism 536. (536a). Hereinafter, the structure of the rigid coupling 533 will be described. FIG. 14 is an enlarged view showing the rigid shaft 533a and the drive shaft 535a of the AC servomotor 535 connected to each other via the rigid coupling 533 and the input shaft 536a of the deceleration mechanism 536. It is a cross section.

As shown, the rigid coupling 533 has a hollow stepped round bar shape (ie, a stepped thick cylinder) as a whole. That is, the rigid coupling 533 includes an output side cylindrical portion 533a having an output side opening portion 533c into which the input shaft 536a of the deceleration mechanism 536 is fitted, and the drive shaft 535a of the AC servomotor 535. It has an input side cylindrical part 533b provided with this input side opening 533d. In this embodiment, since the input shaft 536a of the reduction mechanism 536 is smaller than the drive shaft 535a of the AC servomotor 535, the outer diameter of the output side cylindrical part 533a is the outside of the input side cylindrical part 533b. The alarm tea ceremony has a small diameter.

In addition, in the inside of the output side cylindrical part 533a and the input side cylindrical part 533b (in FIG. 14, the right side of the output side cylindrical part 533a and the left side of the input side cylindrical part 533b), the constriction part 533e and 533f are respectively provided. Formed. The diameters of the narrowing portions 533e and 533f are approximately equal to the diameters of the input shaft 536a of the reduction mechanism 536 and the drive shaft 535a of the AC servomotor 535, respectively. For this reason, the input shaft of the reduction mechanism 536 is provided in a state where the inner circumferential surfaces of the narrowing portions 533e and 533f and the input shaft 536a of the deceleration mechanism 536 and the outer circumference of the drive shaft 535a of the servomotor 535 have almost no gaps. 536a and the drive shaft 535a of the servomotor 535 are accommodated in the constriction parts 533e and 533f.

The diameter of the output side opening part 533c and the input side opening part 533d is comprised larger than the outer diameter of the input shaft 536a of the deceleration mechanism 536, and the drive shaft 535a of the AC servomotor 535, respectively. Fixing rings 630 and 640 are used to fix the output side opening 533c and the input side opening 533d to the input shaft 36a of the reduction mechanism 536 and the drive shaft 535a of the AC servomotor 535, respectively. do.

The fixing ring 630 has an inner ring 632, an outer ring 634, and a bolt 636. The outer circumferential surface 632a of the inner ring 632 is a tapered surface whose diameter decreases toward the AC servomotor side (right side in the drawing). Moreover, the inner peripheral surface 632b of the inner ring 632 becomes a cylindrical surface a little larger than the outer diameter of the input shaft 536a of the reduction mechanism 536. On the deceleration mechanism side (left side in the figure) of the inner ring 632, a flange portion 632c that extends radially outward is formed. The flange portion 632c is provided with a plurality of bolt holes 632d through which the bolt 636 is inserted in the rotational axis A direction. The inner circumferential surface 634a of the outer ring 634 is a tapered surface whose diameter decreases toward the AC servomotor side. Moreover, the outer peripheral surface 634b of the outer ring 634 is a cylindrical surface slightly smaller than the diameter of the output side opening part 533c. Moreover, the outer ring 634 is provided with the female screw 634c which engages with the volt | bolt 636 in multiple numbers. The outer ring 634 and the inner ring 632 are inserted into a gap between the output side opening 533c and the input shaft 536a of the reduction mechanism 536, and then the inner ring 632 is fastened by the bolt 636. And the bolt 636 are firmly tightened, the cylindrical surface 632b of the inner ring 632 strongly presses the input shaft 536a of the reduction mechanism 536, and the cylindrical surface 634b of the outer ring 634. Presses the output side opening part 533c strongly. As a result of the static frictional force generated, the input shaft 536a of the reduction mechanism 536 is firmly fixed to the output side cylindrical portion 533a of the rigid coupling 533, and both are integrated. Further, in the drawing, two sets of bolts 636, bolt holes 632d, and female screws 634c are shown. In reality, a plurality of bolts (for example, 10 are arranged on the circumference around the axis of the reduction mechanism 536). Joe) It is installed.

Similarly, the fixing ring 640 has an inner ring 642, an outer ring 644, and a bolt 646. The outer circumferential surface 642a of the inner ring 642 is a tapered surface whose diameter decreases toward the deceleration mechanism side. The inner circumferential surface 642b of the inner ring 642 is a cylindrical surface that is slightly larger than the outer diameter of the drive shaft 535a of the AC servomotor 535. At the lower end of the inner ring 642, a flange portion 642c that extends radially outward is formed. The flange portion 642c is provided with a plurality of bolt holes 642d through which the bolt 646 is inserted through the rotation axis A direction. The inner circumferential surface 644a of the outer ring 644 is a tapered surface whose diameter decreases toward the deceleration mechanism side. The outer circumferential surface 644b of the outer ring 644 is a cylindrical surface slightly smaller than the diameter of the input side opening 533d. In the outer ring 644, a plurality of female screws 644c engaged with the bolt 646 are formed at positions corresponding to the bolt holes 642d. The outer ring 644 and the inner ring 642 are inserted into a gap between the input side opening 533d and the drive shaft 535a of the AC servomotor 535, and then the inner ring 642 is fastened by the bolt 646 to the outer ring 644. ) And the bolt 646 is firmly tightened, the cylindrical surface 642b of the inner ring 642 strongly presses the drive shaft 535a of the AC servomotor 535, and the cylindrical surface of the outer ring 644. 644b strongly presses the input side opening 533d. As a result of the static frictional force generated, the drive shaft 535a of the AC servomotor 535 is firmly fixed to the input side cylindrical portion 533b of the rigid coupling 533 so that both are integrated. In the drawing, two sets of bolts 646, bolt holes 642d, and female threads 644c are shown. In reality, a circumferential image centering on the rotation center axis of the drive shaft 535a of the AC servomotor 535 is shown. Many (for example, ten sets) are installed in the building.

Since the thicknesses of the output side cylindrical portion 533a and the input side cylindrical portion 533b of the rigid coupling 533 are sufficiently large, the rigid coupling 533 can be regarded as a substantially rigid body. Therefore, the rigid coupling 533 can transmit the torque acting on the drive shaft 535a of the AC servomotor 535 to the deceleration mechanism 536 with high responsiveness.

Next, the structure of the control measurement part of the torsion test apparatus 501 which concerns on this embodiment is demonstrated. 15 is a block diagram of the control measuring unit 700 of the torsion test apparatus 501 according to the present embodiment. The torsion test apparatus 501 according to the present embodiment is capable of repeatedly applying a torsional load to the test piece at short intervals (a few ten cycles per second) so that the fatigue test can be performed in a short time.

The control measurement unit 700 of the torsion test apparatus 501 has a set value indicating unit 710, a drive control unit 720, and a measurement unit 750.

The set value indicating unit 710 is a unit for indicating how to apply a torsional stress to the test piece S. FIG. Specifically, the set value indicating unit 710 is a unit which outputs the angle from the initial position of the attachment flange 537 (or the output shaft of the reduction mechanism 536) as a signal to the drive control unit 720. The setting value indicating unit 710 has an input interface 712 and a waveform generating circuit 714.

The input interface 712 is an interface for connecting the setting value indicating unit 710 and a workstation not shown. The operator of the torsion test apparatus 501 operates the workstation to instruct how to displace the lower stage 531. For example, if performing a static torsion test, the operator operates the workstation and inputs the torsion angle per unit time, and transmits it to the input interface 712. In addition, when performing a fatigue test in which a cyclic load is applied to the test piece S, the operator operates the workstation and inputs the amplitude, frequency, and waveform (which waveforms of sine and triangle waves to use, etc.) of the twist angle. To the input interface 712. Instructions input to the input interface 712 are sent to the waveform generation circuit 714.

The waveform generation circuit 714 analyzes the instruction transmitted from the input interface 712, sequentially calculates the variance of the angle from the initial position of the attachment flange 537, and transmits it to the drive control unit 720. do. In the fatigue test, the test piece S is based on a function synthesized by a function having various amplitudes and frequencies, instead of only twisting the test piece S at a constant waveform and frequency such as a single sine wave or a triangle wave. It is also possible to beat. For example, it is also possible to drive the attachment flange 537 so that the amplitude of the torsion angle changes over time based on a function of multiplying sinusoids of different frequencies.

The angle of the attachment flange 537 is output from the waveform generation circuit 714 as a digital signal. For this reason, the signal transmitted from the waveform generation circuit 714 to the drive control unit 720 is first input to the D / A converter 722 and converted into an analog signal. The angle information of the attachment flange 537 converted into an analog signal is then sent to the amplifier 724. The amplifier 724 amplifies and outputs the angle information of the attachment flange 537 sent from the D / A converter 722.

As described above, in the present embodiment, various tests are performed by the AC servomotor 535 driving the attachment flange 537. Here, the AC servomotor 535 incorporates an encoder for detecting the rotational speed of the drive shaft 535a (FIG. 10), and the rotational speed detected by the encoder is the current position calculating circuit of the drive control unit 720 ( 726.

The current position calculating circuit 726 calculates and outputs the current angle of the attachment flange 537 based on the detection result of the encoder of the AC servomotor 535. The difference between the output of the amplifier 724 and the output of the current position calculation circuit 726 (that is, a signal corresponding to the difference between the target angle of the attachment flange 537 and the current angle) is the current generation circuit 728. Is sent to.

The current generation circuit 728 generates a three-phase current output to the AC servomotor 535 based on the received signal, and outputs this to the AC servomotor 535. As a result, the AC servomotor 535 is driven so that the angle of the attachment flange 37 reaches the target angle.

The magnitude of the torque applied to the test piece S by driving the attachment flange 437 is detected by the load cell 562 and the bridge circuit 756 for taking out the deformation amount of the load cell 562 as an electrical signal. The magnitude of the detected torque is converted into a digital signal by the A / D converter 758 and transmitted to the workstation via the output interface 759. The work station aggregates the magnitude of the torque transmitted from the output interface 759, and generates and displays a graph in which, for example, the time axis is the horizontal axis and the torsional stress applied to the test piece is the vertical axis.

Moreover, it is also possible to perform what is called feedback control which transmits the magnitude | size of the torque which is the output of the A / D converter 758 to the waveform generation circuit 714, and changes the torsional behavior of the test piece S according to a torque. For example, when the rotation angle and the torque of the attachment flange 537 do not show a proportional relationship, that is, when the yield of the test piece S has occurred, control, such as increasing the amplitude of a torsion angle, can be performed.

By using the torsion test apparatus 501 of the above structure, a static breakdown test of a test piece, a fatigue test, etc. can be performed. Here, in this embodiment, the test piece S is twisted using the AC servomotor 535 of high responsiveness and high torque. For this reason, the torsion test apparatus 501 can apply the torque of the maximum number of 100 kN * m to the test piece S, and can also apply a repetitive load to the test piece S at the high frequency of several 10 Hz. Therefore, according to the torsion test apparatus 501 which concerns on this embodiment, it is possible to tear a test piece fatigue in a short time, and can shorten test time.

Moreover, according to the structure of this embodiment, as shown in FIG. 13, rotation of the AC servomotor 535 which is a power source for twisting the test piece S, and the drive shaft 535a of the AC servomotor 535 is decelerated. The reduction mechanism 536 for fixing is fixed to the side plate 532 which is the same plate. Thereby, the relative position of the drive shaft 535a of the AC servomotor 535 and the input shaft 536a of the deceleration mechanism 536 can be positioned and attached with high precision. For this reason, the planting of the drive shaft 535a of the AC servomotor 535 and the input shaft 536a of the deceleration mechanism 536 can be performed easily and more accurately. In addition, it is possible to stably maintain the relative position of each element positioned with high accuracy by arranging all the elements requiring high relative position accuracy on the same plate.

Thus, according to the structure of this embodiment, the planting of the drive shaft 535a of the AC servomotor 535 and the input shaft 536a of the deceleration mechanism 536 can be performed with high precision so that eccentricity may be within 10 micrometers. . For this reason, the bending stress acting between the drive shaft 535a of the AC servomotor 535 and the input shaft 536a of the deceleration mechanism 536 is relatively small by the error of planting. Usually, the coupling for connecting the servomotor and the input shaft of the deceleration mechanism uses a flexible coupling configured to relieve bending stress by interposing a low rigid material (rubber or the like). However, in the present embodiment, as described above, since biaxial planting can be performed with high accuracy, a rigid coupling 533 formed of a material having high rigidity can be used. For this reason, the torque acting on the drive shaft 535a of the AC servomotor 535 can be transmitted to the input shaft 536a of the deceleration mechanism 536 with high responsiveness.

Moreover, in this embodiment, the drive shaft 535a of the AC servomotor 535 and the input shaft 536a of the deceleration mechanism 536 are connected by the rigid coupling 533, but this invention is limited to the said structure. It doesn't happen. That is, even if it is a structure which connects the drive shaft 535a of the AC servomotor 535 and the input shaft 536a of the deceleration mechanism 536 using the semi rigid coupling of 2nd Embodiment of this invention instead of a rigid coupling. do.

As described above, in the first and second embodiments of the present invention, the servomotor, the linear guide and the round ring shape are fixed to a single support plate (table 33), and these members refer to the support plate. To be assembled. For this reason, it is easy to ensure the precision of each member. Moreover, since the distance between a servomotor, a linear guide, and a bearing can be made comparatively small, the error by thermal expansion can be suppressed to the minimum. In addition, since the number of connection points from the ball screw to the drive shaft of the servomotor is kept to a minimum, once the feeding screw and the drive shaft of the servomotor are precisely performed, the rotation center of the drive shaft of the motor and the feed screw are rotated. It is easy to maintain a state where the center is precisely matched (within an error number of 10 mu m). For this reason, the bending stress which arises in a rotating part by the nonlinear connection (eccentricity or connection angle) of a feed screw and the drive shaft of a motor can be suppressed extremely small. As a result, it is possible to connect the feed screw and the drive shaft of the motor by a rigid coupling or a semi-rigid coupling with high torsional rigidity, and the feed screw can be rotated with high responsiveness. Therefore, according to the structure of embodiment of this invention, the universal test apparatus which can drive a crosshead using a feed screw mechanism, and can apply a cyclic load (strain) to a test piece correctly by high cycle correctly is realized. Moreover, such a linear actuator is also useful, for example, for an excitation test apparatus having a specimen by driving the linear actuator with the specimen fixed on the cross head. Moreover, it is preferable that the connection part by a coupling has a torsional rigidity equivalent to or more than the feed screw and the drive shaft of a servomotor.

The rigid coupling has a rigid cylindrical body that is equal to or greater than the rotational shaft of the feed screw and the servomotor, and the drive screw of the servomotor is fitted from the other end thereof to the cylindrical body and fixed to the cylindrical body. In the cylindrical main body, it is preferable that a part of the inner hole into which the feed screw and the drive shaft of the servomotor are fitted is a constriction portion accommodated without substantially a gap with the circumferential surface of the feed screw and the drive shaft of the servomotor. Further, it is preferable that the fixing ring is sandwiched between the barrel inner circumferential surface of the rigid coupling and the feed screw and the circumferential surface of the drive shaft of the motor, so that the feed shaft and the drive shaft of the motor and the rigid coupling are fixed. For example, the fixing ring includes an inner ring whose outer circumference is a tapered surface, an outer ring whose inner circumference is a tapered surface corresponding to the outer circumference of the inner ring, and an inner ring and the outer circumference of the inner ring in contact with the inner circumference of the outer ring. It has a pushing means which presses one side of an outer ring toward the other in the axial direction. With this configuration, the drive shaft and the feed screw of the motor are more firmly connected, so that the torque of the drive shaft of the motor can be transmitted to the feed screw with higher responsiveness.

In the universal testing apparatus and the linear actuator according to the first and second embodiments of the present invention, a semi-rigid coupling may be used instead of the rigid coupling.

By connecting the drive shaft and the feed screw of the motor with a semi-rigid coupling that has flexibility in the bending direction and inhibits transmission of vibration in the extension direction of the drive shaft of the motor, the feed screw is driven with high responsiveness. Even if the shaft is out of position, smooth driving can be performed without generating an extremely large internal deformation, and vibration in the motor drive shaft direction can be prevented.

The semi-rigid coupling preferably has a viscoelastic element made of resin or rubber. Moreover, the semi rigid coupling is comprised so that the damping rate of the vibration of the drive shaft of a servomotor may become the maximum in the natural frequency of a drive shaft. With such a configuration, it becomes possible to effectively damp the axial or radial vibration transmitted from the motor through the drive shaft by the viscoelastic element in the semi-rigid coupling, so that such vibration is hardly transmitted to the output side. have.

Also preferably, the semi-rigid coupling has a pair of outer rings that are rigid elements and an inner ring that includes elastic elements or viscoelastic elements disposed between the pair of outer rings. A tapered hole is formed in the center of the outer ring, and a cylindrical through hole is formed in the center of the inner ring to allow the shaft to be connected to each other. Moreover, the taper surface which can be engaged with the inner periphery of the taper hole of a pair of outer ring is formed in the both ends of the axial direction of the outer periphery of an inner ring, respectively. Insert the feed screw and the drive shaft of the servomotor into the through-holes of the inner ring, and make the inner ring contact with the inner circumference of the tapered hole of the pair of outer rings on the tapered surface of the inner ring, and fix the pair of outer rings with bolts. The shaft is connected via With such a configuration, it is possible to realize a semi-rigid coupling that absorbs vibration in the axial direction with an extremely simple configuration while transmitting the axial output with high responsiveness. This realizes a linear actuator with little vibration noise and high response.

The supporting plate may be provided with an opening through which the feed screw is inserted, and the outer ring of the bearing for rotatably supporting the feed screw may be fixed to the opening. With such a configuration, since the bearing, the linear guide, and the servomotor are integrally formed, it becomes possible to maintain a state where the rotation center of the drive shaft of the motor and the rotation center of the feed screw match more precisely.

At this time, if the bearing is a combination angular ball bearing of the front combined type, the feed screw can be rotatably supported while supporting the heavy load applied to the thrust direction of the feed screw during the test.

The feed screw may be a ball screw, and the nut may be a ball screw nut, that is, a cross head is driven by a ball screw mechanism. With this configuration, the cross head can be reciprocated at high speed with a small backlash, and the repetition speed of the load can be made higher.

In addition, one of the fixed portion and the movable portion of the linear guide has a rail, and the other has a runner block that is engaged with the rail and moves along the rail, and the runner block includes a concave portion surrounding the rail, and the concave portion A groove formed along the moving direction of the runner block, a retracting path formed inside the runner block and connected to both ends of the moving direction of the groove so as to form a closed circuit and a closed circuit, It is preferable to set it as the structure which has a some ball contacted with the said rail. In addition, four said closed circuits are formed in the runner block, The ball arrange | positioned in each of the groove | channel of two closed circuits among these four closed circuits has a contact angle of about +/- 45 degree with respect to the radial direction of a linear guide, The balls arranged in each of the grooves of the closed circuits are preferably configured to have a contact angle of approximately ± 45 degrees with respect to the reverse radial direction of the linear guide.

When the linear guide of such a structure is used, even if a large load is applied to the test piece, the nut of the feed screw mechanism can move smoothly along the linear guide without rattling.

In the torsion test apparatus according to the third embodiment of the present invention, the servomotor and the deceleration mechanism are fixed to the first supporting member (drive end side frame 532) fixed to the frame.

Thus, in the structure of this invention, both a servomotor and a deceleration mechanism are fixed to the 1st support member which is a single member, and these members are assembled based on a 1st support member. For this reason, it is easy to ensure the precision of each member. Moreover, since the distance between a servomotor and a deceleration mechanism can be made comparatively small, the error by thermal expansion can be suppressed to the minimum. In addition, since the number of connection points from the drive shaft of the servomotor to the input shaft of the deceleration mechanism is kept to a minimum, once the drive shaft of the servomotor and the input shaft of the deceleration mechanism are precisely adjusted, the center of rotation of the drive shaft of the motor and It is easy to maintain the state where the feed screw's rotation center is precisely matched (within an error number of 10 µm). For this reason, the bending stress which arises in a rotating part by the nonlinear connection (eccentricity or connection angle) of the input shaft of a deceleration mechanism and the drive shaft of a motor can be made extremely small. Therefore, the input shaft of the reduction mechanism and the drive shaft of the motor can be connected by a rigid coupling or a semi rigid coupling having high torsional rigidity, and the input shaft of the reduction mechanism can be rotated with high responsiveness. Therefore, according to the structure of this invention, the torsion test apparatus which can twist a test piece using a deceleration mechanism, and can repeatedly apply a torsional load to a test piece by high cycle is realized. Preferably, the connecting portion by the coupling connecting the input shaft of the reduction mechanism and the drive shaft of the servomotor has a torsional rigidity equal to or greater than the input shaft of the reduction mechanism and the drive shaft of the servomotor.

In addition, preferably further comprising a second support member (fixed end side frame 522) fixed to the frame, the second gripping portion has a shaft portion, the shaft portion is fixed to the second support member in a cantilever shape, thereby providing 2 holding parts are fixed to the frame. In this configuration, for example, a load cell for measuring the torque acting on the test piece is fixed between the shaft portion and the second support member. More preferably, it has a fixed end side bearing means fixed to the frame and rotatably supporting the shaft portion of the second gripping portion.

In addition, the deceleration mechanism is preferably a wave gear deceleration mechanism. Unlike other deceleration mechanisms such as worm gear mechanisms and planetary gear mechanisms, the wave gear reduction mechanism is suitable for high cycle fatigue tests because the backlash when twisting the specimen repeatedly becomes smaller. Preferably, the wave gear deceleration mechanism is embedded in the first support member to be fixed and thereby integrated with the first support member with high rigidity.

Claims (51)

Servo motor for reciprocating rotational drive shaft, Ball screw, A semi-rigid coupling for coaxially connecting the ball screw and the drive shaft of the servomotor, A nut engaged with the ball screw, A linear guide restricting the moving direction of the nut only in the axial direction of the ball screw; A fixed part to which one end of the test piece abuts or is fixed, The other end of the test piece abuts or is fixed, and is fixed to the nut to move with the nut, The servo motor is fixed to one surface, the support plate is fixed to the linear guide on the other surface, The support plate is provided with an opening through which the ball screw is vertically inserted, and an outer ring of a ball bearing for rotatably supporting the ball screw is fixed to the opening. The semi rigid coupling, A pair of outer rings, rigid body elements having a tapered hole through the center thereof, A taper disposed between the pair of outer rings and having a cylindrical through hole for passing through an axis connecting to the center, and respectively engaged with the inner circumferential surface of the tapered holes of the pair of outer rings on both sides in the axial direction of the outer circumference; Has an inner ring that is formed with an elastic element or a viscoelastic element, The drive shaft of the servomotor is inserted into the through hole of the inner ring from one end, and the ball screw is inserted from the other end, and the tip of the drive shaft of the servomotor and the tip of the ball screw face each other in the through hole of the inner ring. By tightening the pair of outer races with bolts in the extended state, the tapered surfaces of the inner ring are biased inward by the inner circumferential surfaces of the tapered holes of the pair of outer rings, and the drive shaft and the ball screw of the servomotor The universal testing apparatus, characterized in that the drive shaft of the servomotor and the ball screw are connected through the inner ring by being gripped by the inner ring, respectively. delete delete delete delete delete delete The method of claim 1, wherein the semi-rigid coupling provides torsional rigidity equal to or greater than that of the ball screw and the drive shaft of the servomotor to the connection between the ball screw and the drive shaft of the servomotor, and also provides flexibility in the bending direction. And the transmission of vibration in the extension direction of the drive shaft of the servomotor. The universal testing apparatus according to claim 8, wherein the semi-rigid coupling includes a viscoelastic element, and the damping rate of the vibration in the direction of the drive shaft of the servomotor is configured to be the maximum at the natural frequency of the drive shaft. The universal testing apparatus according to claim 1, wherein at least part of the viscoelastic element is formed of resin or rubber. The universal testing apparatus according to claim 1, wherein the servomotor is a low inertia servomotor capable of inverting driving at a repetition rate of 500 Hz. The universal testing apparatus according to claim 8, wherein a load of several 100 kN can be applied to the test piece at a repetition rate of several 100 Hz. delete delete The universal testing apparatus according to claim 1, wherein the ball bearing has a combined frontal type angular ball bearing in which the front faces of the pair of angular ball bearings are combined to face each other. delete The universal testing apparatus according to claim 1, wherein the supporting plate is a single metal plate or a plurality of metal plates integrated by welding. 18. The universal testing apparatus according to claim 17, wherein the supporting plate is welded to a leg of the universal testing apparatus. According to claim 1, The linear guide has a first portion fixed to the fixing portion, and a second portion fixed to the nut, One of the first portion and the second portion has a rail, and the other has a runner block that is engaged with the rail and moves along the rail, The runner block, A recess surrounding the rail, In the recess, a groove formed along the moving direction of the runner block, A retreat path formed in the runner block and connected to both ends of the groove in the moving direction to form a closed circuit together with the groove; And a plurality of balls which are in contact with the rail when circulating the closed circuit and located in the groove. The runner block is provided with four closed circuits, A ball disposed in each of the grooves of the two closed circuits of the four closed loops has a contact angle of ± 45 degrees with respect to the radial direction of the linear guide, and a ball disposed in each of the grooves of the other two closed circuits is the inverse of the linear guide. The universal testing apparatus characterized by having a contact angle of ± 45 degrees with respect to the radial direction. delete delete delete Servo motor for reciprocating rotational drive shaft, Ball screw, A semi-rigid coupling for coaxially connecting the ball screw and the drive shaft of the servomotor, A nut engaged with the ball screw, A linear guide restricting the moving direction of the nut only in the axial direction of the ball screw; The servo motor is fixed to one surface, the support plate is fixed to the linear guide on the other surface, The support plate is provided with an opening through which the ball screw is vertically inserted, and an outer ring of a ball bearing for rotatably supporting the ball screw is fixed to the opening. The semi rigid coupling, A pair of outer rings, rigid body elements having a tapered hole through the center thereof, A taper disposed between the pair of outer rings and having a cylindrical through hole for passing through an axis connecting to the center, and respectively engaged with the inner circumferential surface of the tapered holes of the pair of outer rings on both sides in the axial direction of the outer circumference; Has an inner ring that is formed with an elastic element or a viscoelastic element, The driving shaft of the servomotor is inserted into the through hole of the inner ring from one end, and the ball screw is inserted from the other end thereof, and the tip of the driving shaft and the tip of the ball screw are spaced apart from each other in the through hole of the inner ring. By tightening the pair of outer rings with bolts, the tapered surface of the inner ring is biased inward by the inner circumferential surface of the tapered hole of the pair of outer rings, and the drive shaft and the ball screw are respectively gripped by the inner ring. And the drive shaft and the ball screw are connected through the inner ring. delete delete delete delete delete delete 25. The method of claim 24, wherein the semi-rigid coupling provides torsional rigidity equal to or greater than the ball screw and the drive shaft of the servomotor to the connection between the ball screw and the drive shaft of the servomotor, and provides flexibility in the bending direction. And directing and inhibiting transmission of vibration in the extension direction of the drive shaft of the servomotor. 32. The linear actuator according to claim 31, wherein the semi-rigid coupling includes a viscoelastic element, and the damping rate of vibration in the direction of the drive shaft of the servomotor is configured to be the maximum at the natural frequency of the drive shaft. 25. The linear actuator according to claim 24, wherein at least part of the viscoelastic element is formed of resin or rubber. 25. The linear actuator according to claim 24, wherein the servomotor is a low inertia servomotor capable of inverting driving at a repetition rate of 500 Hz. 32. The linear actuator according to claim 31, wherein a load of several 100 kN can be applied at a repetition rate of several 100 Hz. delete delete The linear actuator according to claim 24, wherein the ball bearing has a combined angular ball bearing of the front combined type in which the front faces of the pair of angular ball bearings are combined to face each other. delete 25. The linear actuator according to claim 24, wherein the support plate integrates a plurality of metal plates by one metal plate or by welding. The linear guide according to claim 24, wherein the linear guide has a first portion fixed to a fixed portion to which one end of the test piece abuts or is fixed, and a second portion fixed to the nut, One of the first and second portions of the linear guide has a rail, and the other has a runner block engaged with the rail and movable along the rail, The runner block, A recess surrounding the rail, In the recess, a groove formed along the moving direction of the runner block, A retreat path formed in the runner block and connected to both ends of the groove in the moving direction to form a closed circuit together with the groove; And a plurality of balls which are in contact with the rail when circulating the closed circuit and located in the groove. 42. The said runner block is provided with four said closed circuits, The ball disposed in each of the grooves of the two closed circuits of the four closed loops has a contact angle of ± 45 degrees with respect to the radial direction of the linear guide, and the ball disposed in each of the grooves of the other two closed circuits A linear actuator having a contact angle of ± 45 degrees with respect to the reverse radial direction. The frame fixed to the base, Servo motor for reciprocating rotational drive shaft, Wave gear reduction mechanism, A semi-rigid coupling coupling the input shaft of the wave gear reduction mechanism and the drive shaft of the servomotor coaxially; A first gripping portion fixed to an output shaft of the wave gear deceleration mechanism and holding one end of a test piece; A second gripping portion fixed to the frame and gripping the other end of the test piece; The first support member is fixed to the frame, the servo motor is fixed to one surface, the wave gear reduction mechanism is fixed to the other surface, The semi rigid coupling, A pair of outer rings, rigid body elements having a tapered hole through the center thereof, A taper disposed between the pair of outer rings and having a cylindrical through hole for passing through an axis connecting to the center, and respectively engaged with the inner circumferential surface of the tapered holes of the pair of outer rings on both sides in the axial direction of the outer circumference; Has an inner ring that is formed with an elastic element or a viscoelastic element, The drive shaft of the servomotor is inserted into the through hole of the inner ring from one end, and the input shaft of the wave gear reduction mechanism is inserted from the other end thereof, and the tip of the drive shaft and the tip of the input shaft face each other in the through hole of the inner ring. By tightening the pair of outer rings with the bolts in the extended state, the tapered surfaces of the inner ring are biased inward by the inner circumferential surfaces of the tapered holes of the pair of outer rings, respectively, and the drive shaft and the input shaft are respectively fastened to the inner ring. The gripping test apparatus, characterized in that the drive shaft and the input shaft are connected through the inner ring. 45. The method of claim 43, wherein the semi-rigid coupling provides a torsional rigidity equal to or greater than the input shaft of the wave gear reduction mechanism and the drive shaft of the servo motor to the connection between the input shaft of the wave gear reduction mechanism and the drive shaft of the servomotor. And torsional flexibility in the bending direction, and further to inhibit transmission of vibration in the extension direction of the drive shaft of the servomotor. The torsion test apparatus according to claim 43, wherein the semi-rigid coupling includes a viscoelastic element, and the damping rate of the vibration in the direction of the drive shaft of the servomotor is configured to be the maximum at the natural frequency of the drive shaft. 44. The torsion test apparatus of claim 43, wherein the servomotor is a low inertia servomotor capable of inverting driving at a repetition rate of 500 Hz. 44. The apparatus of claim 43, further comprising a second support member secured to said frame, The second gripping portion has a shaft portion, And the second gripping portion is fixed to the frame by the shaft portion being fixedly supported by the second supporting member in a cantilever shape. 48. A torsion test apparatus as set forth in claim 47, further comprising a fixed end side bearing means fixed to said frame and rotatably supporting the shaft portion of said second gripping portion. 48. The torsion test apparatus according to claim 47, wherein a load cell for measuring torque acting on the test piece is fixed between the shaft portion and the second support member. The torsion test apparatus according to claim 43, wherein a torque of several 100 kN · m can be applied to the test piece at a frequency of several 10 Hz. The torsion test apparatus according to claim 43, wherein the wave gear deceleration mechanism is fixed by being embedded in the first support member.

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