JP2011133317A - Displacement measurement apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a displacement measurement apparatus for correctly measuring a relative displacement of a second to be measured section to a first to be measured section even if the displacement of the second to be measured object is rapidly changed in a time axis. <P>SOLUTION: The displacement measurement apparatus includes a sensor body section 31 fixed to an outer shaft (the first to be measured section) 11, a stylus section 32 retractable to the sensor body section 31, and a driven means for causing the stylus section 32 to be driven to an inner shaft (the second to be measured section ) 12, and measures the relative displacement of the inner shaft 12 to the outer shaft 11 by detecting the retraction quantity of the stylus section 32 to the sensor body section 31. The stylus section 32 is retractably held without being elastically biased to the sensor body section 31. The stylus section 32 is driven to the inner shaft 12 by causing an iron contactor (a section to be held) 42 provided on the side of the stylus section 32 to be sucked to a magnet (a holding section) 35 provided on the side of the inner shaft 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a displacement measuring device for measuring a relative displacement of a second measured part with respect to a first measured part.

  Conventionally, a displacement sensor such as a dial gauge described in Patent Document 1 is generally used for a displacement measuring apparatus that measures the relative displacement of the second measured part with respect to the first measured part. This type of displacement sensor includes a sensor main body fixed to the first measured part, a stylus that can be moved back and forth with respect to the sensor main body, and an axial direction of the stylus with respect to the sensor main body. And a spring member that causes the stylus part to follow the second measured part by elastically urging outward and pressing the second measured part, and detects the amount of withdrawal of the stylus part relative to the sensor body part. Accordingly, the relative displacement of the second measured part with respect to the first measured part is measured.

JP-A-2005-300319

  As described above, a conventional displacement sensor such as a dial gauge is configured to cause the stylus part to follow the second measured part by pressing the stylus part to the second measured part with a spring member. For example, when the displacement of the second measured part changes rapidly with respect to the time axis, such as when the second measured part vibrates at high speed with respect to the first measured part, the stylus part is In some cases, it is impossible to accurately follow the operation of the second measured part, and an accurate measurement result cannot be obtained. Further, for example, when measuring a displacement by applying a predetermined driving force to the second measured part, it is conceivable that the spring force becomes a part of the driving force and adversely affects the measurement result.

  The present invention has been made in view of such conventional problems, and the displacement of the second measured part is time-dependent, such as when the second measured part vibrates at high speed with respect to the first measured part. Even in the case of a sudden change with respect to the axis, the stylus part accurately follows the operation of the second measured part to accurately determine the relative displacement of the second measured part with respect to the first measured part. An object of the present invention is to provide a displacement measuring device capable of measuring.

  The present invention includes a sensor main body fixed to the first measured part, a stylus part that can be moved in and out of the sensor main part, and a follower that moves the stylus part to follow the second measured part. A displacement measuring apparatus for measuring a relative displacement of the second measured part with respect to the first measured part by detecting an amount of withdrawal of the stylus part with respect to the sensor main body part. The part is held so as to be freely withdrawn and retracted without being elastically biased with respect to the sensor body part, and the follower means includes a holding part provided on the second measured part side or the stylus part side. And a held part that is provided on the stylus part side or the second measured part side and is held by the holding part.

  According to the present invention, even when the displacement of the second measured part changes suddenly with respect to the time axis, the stylus part can accurately follow the operation of the second measured part. In addition, since the stylus part is not elastically biased, the force becomes a part of the driving force to the second measured part and does not adversely affect the measurement result, and the second against the first measured part. It is possible to accurately measure the relative displacement of the part to be measured.

It is the whole side view and front view of the displacement measuring device which show one Embodiment of this invention. It is a partial sectional view of a telescopic shaft as an example of an object to be measured. It is a partial cross section figure of a displacement sensor. It is an exploded sectional view of the tip side of a stylus part. It is a perspective view which shows the mounting state of the displacement sensor and magnet with respect to a to-be-measured object. It is a top sectional view showing the mounting state of the displacement sensor and magnet to the object to be measured. It is an example of the displacement measurement result (a) by the displacement measuring device of this embodiment, and the displacement measurement result (b) by the conventional displacement measuring device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1-7 illustrate one embodiment of the present invention. The displacement measuring apparatus 1 according to the present embodiment is for measuring the displacement (backlash) in the torsional direction of an object 2 to be measured such as a telescopic shaft, and holds the object 2 to be measured as shown in FIG. A measured object holding unit 3, a drive unit 4 for applying a torque in a predetermined pattern to the measured object 2 held by the measured object holding unit 3, and a displacement for measuring a torsional direction displacement of the measured object 2 A control unit 6 that performs various control processes such as a drive control process of the sensor 5 and the drive unit 4 and a post process based on a measurement value of the displacement sensor 5, a keyboard that performs various setting inputs to the control unit 6, an operation panel The operation input unit 7 and the display unit 8 for displaying various information such as measurement results output from the control unit 6 are mounted on the apparatus base 9.

  As shown in FIG. 2, the telescopic shaft, which is an example of the device under test 2, has an outer shaft (first device to be measured) 11 formed in a cylindrical shape, and is also formed in a cylindrical shape and within the outer shaft 11. An inner shaft (second measured portion) 12 to be fitted and a pair of universal joints 13 and 14 provided at the outer shaft 11 and the end of the inner shaft 12 are provided. A large number of spline teeth 11a and 12a are formed on the inner peripheral surface side of the outer shaft 11 and the outer peripheral surface side of the inner shaft 12, respectively. By engaging these, the outer shaft 11 and the inner shaft 12 are in the axial direction. It is connected so as to be slidable and capable of transmitting torque.

  The object-to-be-measured holding unit 3 includes, for example, a pair of driving side chuck 15 and fixed side chuck 16 arranged above and below, and at least the driving side chuck 15 and the stationary side chuck 16 according to the size of the object to be measured 2. On the other hand, for example, a position adjusting means 17 for adjusting the position of the fixed side chuck 16 is provided. The driving side chuck 15 holds the upper end side of the DUT 2 in a state where the driving force from the driving unit 4 can be transmitted. For example, the driving side chuck 15 is driven to the front side of the support plate 18 erected on the apparatus base 9. The universal joint 14 (FIG. 2) on the inner shaft 12 side of the device under test 2 is fixed to the drive side chuck 15 in this embodiment.

  The fixed side chuck 16 holds the lower end side of the DUT 2 in a non-rotatable manner. For example, the fixed side chuck 16 is fixed upward on a lifting platform 19 supported so as to be movable up and down on the front side of the support plate 18. In the embodiment, the universal joint 13 on the outer shaft 11 side of the DUT 2 is fixed to the fixed chuck 16. The lift 19 is supported on the support plate 18 via a position adjusting means 17 such as a feed screw mechanism, and the height position thereof can be adjusted by manually operating the handle 20, for example. Yes.

  The drive unit 4 is disposed, for example, on the upper side of the measurement object holding unit 3. The motor 21 is mounted on the front side of the support plate 18 with the drive shaft 21 a facing downward, and the motor 21 and the drive side chuck 15. And a transmission shaft 22 disposed in the vertical direction, for example, an encoder 23 for measuring the rotational displacement of the transmission shaft 22, for example, a torque sensor 24 for measuring torque in the transmission shaft 22, and the like.

  The transmission shaft 22 has an upper end that is integrally connected to a drive shaft 21 a of the motor 21 via, for example, a coupling 25, and a lower end that is fixed to the drive side chuck 15. (Torque) is transmitted to the DUT 2 via the transmission shaft 22 and the drive side chuck 15. The coupling 25 has a function as a torque limiter that cuts off torque transmission between the drive shaft 21a and the transmission shaft 22 during overload.

  The motor 21 is controlled in the forward / reverse direction by controlling the control unit 6 based on the measured values of the encoder 23, the torque sensor 24, etc., for example, so as to repeatedly apply a predetermined value of torque to the device under test 2 in the forward / reverse direction with a predetermined period. To be driven.

  The displacement sensor 5 is, for example, a contact-type displacement sensor that employs a general differential transformer system. As shown in FIG. 3 and the like, the displacement sensor 5 can freely move in and out of one end side in the axial direction of the sensor body 31. As shown in FIG. 5 and the like, the sensor main body 31 is fixed to the outer shaft 11 of the object to be measured 2 by the sensor holder 33, and the stylus 32 is connected to the magnet holder 34. Thus, the magnet 35 is attracted to the magnet 35 fixed to the inner shaft 12 of the object 2 to be measured and follows the operation of the inner shaft 12 in the twisting direction.

  As shown in FIG. 3, the sensor main body 31 includes, for example, a substantially cylindrical housing 36, a primary coil 37a disposed along the inner surface of the housing 36, and a pair of 2 disposed on both sides in the axial direction. A secondary coil 37b and a bearing portion 38 provided in the housing 36 and holding the stylus portion 32 so as to be axially swingable at one or a plurality of locations in the axial direction are provided. Further, the stylus part 32 includes a shaft part 40 having a movable iron core 39 and a contact 42 attached to the front end side of the shaft part 40 via an insulating pin 41, and the rear end side of the shaft part 40 is It is inserted into the sensor main body 31 and is held so as to be able to move in and out in the axial direction via a bearing 38.

  When the primary coil 37a on the sensor main body 31 side is excited with an alternating current, the movement of the movable core 39 accompanying the movement of the stylus part 32 causes the movement of the movable core 39 according to the positional relationship between the movable core 39 and the two secondary coils 37b. Since an AC voltage is generated in the secondary coil 37b, the amount of movement of the stylus part 32, that is, the displacement can be measured based on the voltage. Note that the displacement sensor 5 of this embodiment does not include a spring member or the like that elastically biases the stylus part 32 in the protruding direction, for example, with respect to the sensor main body part 31. On the other hand, it can move freely in the direction of withdrawal.

  The contact 42 is made of, for example, iron (an example of a ferromagnetic material), and has a tip side formed in, for example, a substantially hemispherical shape, as shown in FIG. 4, and a detachable male screw portion 43, for example, provided on the rear end side. The insulating pin 41 is formed in, for example, a cylindrical shape from nylon or other non-magnetic material, and is attached and detached between the shaft portion 40 and the contact 42 so that the shaft portion 40 and the contact 42 do not contact each other. It is installed freely.

  That is, as shown in FIG. 4, the insulating pin 41 is formed so that the female screw portions 44 and 45 are not penetrated from each other by inserting, for example, a helicate into the tap hole at both ends, and the female screw portion 44 on the rear end side. A stud bolt 46 is attached to form a male threaded portion 47, and the male threaded portion 47 on the rear end side is screwed into a female threaded portion 48 formed on the front end side of the shaft portion 40, so that the shaft portion 40 can be attached and detached. The contactor 42 is detachably held by being screwed into the female screw part 45 on the distal end side and the male screw part 43 on the contactor 42 side.

  As shown in FIGS. 5 and 6, the sensor holder 33 for fixing the displacement sensor 5 to the outer shaft 11, for example, one end side of the first and second arm portions 51a and 51b parallel to each other is integrally connected by a connecting portion 51c. The clamp main body 51 formed in a substantially U-shape and the clamp block 52 fixed to the inner surface side of the first arm portion 51a and formed with, for example, a V groove 52a on the opposite surface side of the second arm portion 51b. A clamp bolt 53 screwed to the second arm portion 51b so that the tip portion faces the clamp block 52, and a sensor main body 31 of the displacement sensor 5 provided on the tip side of the first arm portion 51a, for example. A sensor holding portion 54 that is detachably held, and is detachably fixed to the outer shaft 11 by sandwiching the outer shaft 11 between the clamp block 52 and the clamp bolt 53. . The displacement sensor 5 is held by the sensor holder 33 in a plane perpendicular to the axis of the outer shaft 11 and the sensor axis not intersecting the axis of the outer shaft 11 as shown in FIG.

  In addition, as shown in FIG. 5, the magnet holder 34 for fixing the magnet 35 to the inner shaft 12 is substantially formed by integrally connecting one end sides of the first and second arm portions 55a and 55b parallel to each other by a connecting portion 55c. A clamp body 55 formed in a U-shape, a clamp block 56 fixed on the inner surface side of the first arm portion 55a and formed with, for example, a V-groove 56a on the surface facing the second arm portion 55b, and a tip A clamp bolt 57 screwed to the second arm portion 55b so that the portion faces the clamp block 56, and a magnet holding arm 58 fixed to the first arm portion 55a, for example, and the clamp block 56 and the clamp bolt 57 The inner shaft 12 is sandwiched between the inner shaft 12 and the inner shaft 12 so as to be detachable. For example, the magnet holding arm 58 protrudes from the first arm portion 55a substantially parallel to the inner shaft 12, and the magnet 35 is mounted on the tip side thereof.

  As shown in FIG. 6, the sensor holder 33 and the magnet holder 34 are arranged such that the contact 42 contacts (adsorbs) the magnet 35 in a state where the stylus portion 32 of the displacement sensor 5 is, for example, approximately in the middle of its movable range. In addition, the mounting height and angle of each other are adjusted. Thereby, the sensor main body 31 of the displacement sensor 5 is fixed to the outer shaft 11 via the sensor holder 33, and the stylus portion 32 of the displacement sensor 5 is attracted to the magnet 35 fixed to the inner shaft 12 by the magnet holder 34. Since the inner shaft 12 is driven, the displacement sensor 5 can measure the relative displacement of the inner shaft 12 in the torsional direction with respect to the outer shaft 11.

  Moreover, since the stylus part 32 has an insulating pin 41 made of a non-magnetic material between the shaft part 40 provided with the movable iron core 39 and the iron contactor 42, the displacement sensor 5 uses magnetism. In spite of adopting the differential transformer system, the adverse effect of the magnet 35 on the measurement result can be eliminated. Furthermore, the tip of the contact 42 is formed in a substantially hemispherical shape, and as shown in FIG. 6, for example, is brought into contact with the end surface 35 a of the magnet 35 at approximately one point. Even if the inner shaft 12 is relatively displaced in the torsional direction, the angle formed by the end surface 35a of the magnet 35 and the axis of the stylus portion 32 changes slightly, but it is always unaffected. Accurate displacement measurement is possible.

  When the inner shaft 12 is displaced relative to the outer shaft 11 in the torsional direction in this way, the relative locus of the stylus portion 32 with respect to the sensor body portion 31 is actually an arc shape. The measured value obtained by the sensor 5 is a linear displacement. However, since the difference between them is slight, for example, when measuring the backlash angle in the torsional direction of the DUT 2, it is considered that “the length of the arc = the length of the straight line”, and the measured value by the displacement sensor 5 ( Linear displacement) and the distance between the axes of the DUT 2 and the displacement sensor 5 can be calculated using a trigonometric function.

  FIG. 7A shows the torsional direction of the inner shaft 12 relative to the outer shaft 11 when the displacement measuring apparatus 1 according to the present embodiment applies a constant range of torque to the device under test 2 at a constant period. The displacement measurement results are shown, with the horizontal axis representing the measured displacement by the displacement sensor 5 and the vertical axis representing the torque input value. FIG. 7B shows a displacement measurement result when only the displacement sensor is changed to a conventional displacement sensor with a built-in spring member, compared to FIG. 7A. In the conventional displacement sensor used in FIG. 7B, the stylus portion is elastically biased in the protruding direction by a spring member, and the stylus portion is pressed against a predetermined portion on the inner shaft 12 side by the spring force. Thus, it is assumed that the stylus part is driven by the inner shaft 12.

  7 (a) and 7 (b), the waveform is drawn in the direction of the arrow shown in the figure, but in FIG. 7 (b) using the conventional displacement sensor, the waveform immediately after the direction of the torque is reversed, A portion parallel to the vertical axis, that is, a portion (P and Q) where the measured displacement does not change although the torque changes appears. In the case of FIG. 7B, since the stylus part is crimped to the inner shaft 12 side by the spring member, the measurement force (the urging force by the spring member, between the sensor main body part and the stylus part). This is presumably because the stylus part cannot follow the sudden change in displacement on the inner shaft 12 side.

  Note that the measurement force of the displacement sensor is greatest at the moment when it starts to move from the stationary state (maximum static friction force> dynamic friction force). Therefore, when a conventional displacement sensor having a measurement force of 0 is used, FIG. A portion parallel to the vertical axis, such as P and Q portions, always appears. Therefore, in the measurement using a conventional displacement sensor, if a measurement result with a sudden change in the displacement is obtained, determine whether it is due to the actual displacement or the influence of the measuring force of the sensor. I can't.

  On the other hand, in FIG. 7A by the displacement measuring apparatus 1 of the present embodiment, the portion immediately parallel to the vertical axis does not appear even in the waveform immediately after the direction of the torque is reversed, and the measurement is performed according to the variation of the torque. The displacement is constantly changing. This is because in the displacement measuring apparatus 1 of the present embodiment, the stylus part accurately follows the sudden change in the displacement on the inner shaft 12 side by attracting the stylus part to the inner shaft 12 side with a magnet. It is thought that it is because it is made. Further, since the displacement sensor 5 of the present embodiment is a differential transformer type, the frictional force generated between the stylus part 32 and the sensor main body part 31 is minimal, whereby the followability of the stylus part 32 is reduced. It is more improved. As described above, in the displacement sensor according to the present invention, since the adverse effect on the measurement result due to the measuring force is eliminated, it is possible to accurately perform the measurement in which the displacement actually changes suddenly.

  As described above, in the displacement measuring apparatus 1 according to the present embodiment, the stylus part 32 of the displacement sensor 5 is held so as to be freely retracted without being elastically biased with respect to the sensor main body part 31. (Second measured part) It is composed of a magnet (holding part) 35 provided on the 12 side and an iron contactor 42 provided on the stylus part 32 side and attracted and held by the magnet (holding part) 35. Since the stylus part 32 is driven by the follower means to follow the inner shaft (second measured part) 12, even if the displacement of the inner shaft 12 changes rapidly with respect to the time axis, It is possible to accurately measure the relative displacement of the inner shaft 12 with respect to the outer shaft 11 by causing the needle portion 32 to accurately follow the operation of the inner shaft 12.

  Further, since the spring member for elastically urging the stylus portion 32 is not provided, the spring force does not become a part of the input torque and does not adversely affect the measurement result. In addition, since the spring member is removed from the conventional general displacement sensor and the contact 42 is made of iron and the other party with which the contact 42 abuts only needs to be made of a magnet, the cost can be kept low. There is also an advantage that the apparatus is not increased in size.

  Moreover, since the stylus part 32 of the displacement sensor 5 and the inner shaft (second measured part) 12 side are connected by a magnet, workability during measurement is improved and damage to the displacement sensor 5 is prevented. it can. That is, when the workpiece is replaced, the stylus part 32 of the displacement sensor 5 can be easily separated from the second measured part, so that the workability between measurements is improved and the cycle time is expected to be reduced. An abnormal load does not act on the stylus part 32 of the displacement sensor 5 during the attaching / detaching operation of the sensor, and the displacement sensor 5 can be prevented from being damaged.

  Further, since the iron contact 42 is fixed to the distal end side of the stylus part 32 via an insulating pin 41 made of a non-magnetic material, a differential transformer type displacement sensor 5 using magnetism is employed. Nevertheless, the adverse effect of the magnet 35 on the measurement results can be eliminated. Furthermore, the tip of the contact 42 is formed in a substantially hemispherical shape, and comes into contact with the end surface 35 a of the magnet 35 at, for example, a substantially single point, so that the inner shaft 12 is twisted with respect to the outer shaft 11. By relatively displacing in the direction, accurate displacement measurement is always possible without being affected by the slight change in the angle between the end surface 35a of the magnet 35 and the axis of the stylus 32. It is.

  As mentioned above, although embodiment of this invention was illustrated, this invention is not limited to this embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the embodiment, an example has been shown in which the telescopic shaft is the object to be measured, and the relative displacement in the twist direction of the inner shaft (second measured portion) 12 with respect to the outer shaft (first measured portion) 11 is measured. The relative displacement other than the torsional direction may be measured. For example, the same telescopic shaft as in the embodiment may be a measurement object, and the relative displacement in the expansion / contraction direction of the inner shaft (second measured portion) 12 with respect to the outer shaft (first measured portion) 11 may be measured.

  In the displacement measuring apparatus according to the present invention, since the stylus part 32 can follow the movement of the second measured part regardless of the installation direction of the displacement sensor 5, for example, the stylus part 32 is arranged to face upward. For example, the displacement sensor 5 can be arranged in any direction according to the type of the object to be measured. In addition, since the displacement measuring device of the present invention has good followability of the stylus part, it is compatible with general displacement measurement. In addition to constantly sliding parts and vibrating parts, measurement of stick-slip, displacement measurement when an object starts to move It is also possible to measure the timing of movement. It is also effective for measuring the displacement of a workpiece that is displaced with a low load.

  The displacement sensor is not limited to the differential transformer type, and may be a magnet scale having a magnetized scale and a slide sensor unit that senses the magnetism, an encoder, an interferometer, or the like. Among them, for example, a displacement sensor using a magnescale has a very small frictional force generated between the stylus part and the sensor main body, like the differential transformer type displacement sensor. Well ideal.

  In the embodiment, a magnet 35 is fixed to the inner shaft (second measured portion) 12 side and the contact 42 on the stylus portion 32 side is made of iron (strong) as driven means for moving the stylus portion to the second measured portion. Although an example of a magnetic body) has been shown, for example, a contact on the stylus part side may be a magnet, and a contact plate made of a ferromagnetic material may be fixed on the second measured part side. Of course, the ferromagnetic material is not limited to iron. Further, the non-magnetic material disposed between the contact 42 and the shaft portion 40 is not limited to nylon. When using a displacement sensor that is not affected by magnetism, it is not necessary to interpose a non-magnetic material between the contact and the shaft portion.

  In the embodiment, the tip of the contact 42 is formed in a substantially hemispherical shape so as to contact the end surface 35a of the magnet 35 at, for example, approximately one point, but the tip of the contact 42 may be pointed. Good. Further, the tip of the magnet 35 may be substantially hemispherical or pointed, and the end face on the contact 42 side may be formed flat, or both the magnet 35 and the contact 42 may be substantially hemispherical or pointed. .

  Further, as with the combination of the magnet and the ferromagnetic material, as the follower means for attracting the held portion provided on the other side by the holding portion provided on one side of the stylus portion and the second measured portion, Those using electrostatic force, those using vacuum, and the like can be considered, and those using an adhesive as a method similar to adsorption can be considered. However, there is a concern about the influence of noise for those that use electrostatic force, and those that use vacuum are expensive due to the need to provide a vacuum circuit, and those that use adhesives are not adhesive. There is. In addition, as a follower that uses a method other than suction, various chuck devices such as a collet chuck, a three-claw chuck, and a diaphragm chuck may be used. In the case of a magnet that does not use a magnet, such as a collet chuck, it is not necessary to dispose a non-magnetic material between the contact and the shaft portion.

  For the holder for fixing the sensor main body of the displacement sensor to the first measured part and the holder for holding the held part such as a ferromagnetic or the holding part such as a magnet to the second measured part, the type of the measured object An appropriate configuration may be employed according to the above.

1 Displacement measuring device 11 Outer shaft (first measured part)
12 Inner shaft (second measured part)
31 Sensor body part 32 Stylus part 35 Magnet (holding part)
42 Contact (ferromagnet, held part)
41 Insulation pin (non-magnetic material)

Claims (5)

A sensor main body fixed to the first measured part; a stylus part that can be moved back and forth with respect to the sensor main part; and a follower that moves the stylus part to follow the second measured part; In the displacement measuring device that measures the relative displacement of the second measured part with respect to the first measured part by detecting the amount of movement of the stylus part with respect to the sensor main body part, the stylus part is the sensor. The main body is held so as to be freely retractable without being elastically urged, and the follower includes a holding part provided on the second measured part side or the stylus part side, and the stylus A displacement measuring apparatus comprising: a portion to be held or a portion to be held, which is provided on a portion side or the second portion to be measured and held by the holding portion. The displacement measuring apparatus according to claim 1, wherein the holding unit is configured to hold the held portion by suction. The displacement measuring device according to claim 2, wherein the holding unit and the held unit are configured by a magnet and a ferromagnetic material attracted to the magnet. The displacement measuring apparatus according to claim 3, wherein the magnet or the ferromagnetic body is fixed to a distal end side of the stylus part via a non-magnetic body. 5. The displacement measuring device according to claim 3, wherein at least one tip side of each of the magnet and the ferromagnetic material is formed in a pointed shape or a substantially spherical surface so that the magnet and the ferromagnetic material are in contact with each other at substantially one point.

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