JP7355372B2 - Collets for dynamic balance testers and dynamic balance testers - Google Patents

Description

The present invention relates to a collet for a dynamic balance tester, and a dynamic balance tester including this collet.

Patent Document 1 below discloses a dynamic balance tester that measures the unbalance of a test object by rotating a spindle to which the test object is fixed at a predetermined speed, and a collet that fixes the test object to the spindle. are doing. The collet has a cylindrical part that is fitted into the inner peripheral part of the test object and can be expanded and contracted. The cylindrical portion is press-fitted into the inner peripheral portion of the test object by expanding its diameter. Thereby, the test object is gripped by the collet and fixed to the spindle.

JP 2019-128283 Publication

At work sites where dynamic balance testing machines are installed, it is desired to shorten the cycle time for unbalance measurement in order to improve work efficiency. In order to shorten cycle time, it is important to shorten the acceleration/deceleration time of rotation of a spindle to which a test object is fixed in a dynamic balance tester. On the other hand, in order to measure unbalance using a dynamic balance tester, the rotational speed of the spindle must be increased to a certain predetermined speed. Considering this situation, it is conceivable to increase the acceleration of the spindle up to the predetermined speed or the deceleration of the spindle from the predetermined speed in order to shorten the acceleration/deceleration time of the rotation of the spindle. However, when the acceleration or deceleration of the spindle increases, a large torque load is applied to the collet that grips the test object due to the acceleration or deceleration of the spindle. When such a torque load is applied to the collet, if the collet does not have enough gripping force to grip the test object, slippage will occur between the collet and the test object. In order to prevent slippage, it is necessary to increase the gripping force, and for this purpose, it is necessary to lower the spring constant of the collet so that the diameter of the collet further expands and is press-fitted into the inner circumference of the test object. Conceivable. However, if the spring constant of the collet decreases, there is a risk that the collet will be twisted and damaged by the aforementioned torque load.

SUMMARY OF THE INVENTION An object of the present invention is to provide a collet for a dynamic balance tester that can prevent damage due to torque loads, and a dynamic balance tester including this collet.

The present invention is a collet (4) that connects a test object (2) to a rotating part (3) that rotates in a dynamic balance tester (1) so as to be able to rotate integrally with the inner peripheral part (2A) of the test object. ) is a cylindrical gripping part (22) that is fitted into the inner peripheral part and grips the inner circumferential part, in which a plurality of grooves (4A) are formed in line in the circumferential direction (S) of the gripping part, and the grooves a gripping part that can be expanded and contracted according to a change in the groove width (W); and a gripping part that is connected one by one to a portion (22F) between the grooves adjacent to each other in the circumferential direction in the gripping part and arranged in the circumferential direction. a plurality of spring parts (23), which are provided in at least one of the grip part and the spring part, and which are elastically deformable in order to expand and contract the grip part; This is a collet for a dynamic balance tester, including a rotation preventing part (24) that prevents the rotation part from rotating with respect to the rotating part. Note that alphanumeric characters in parentheses represent corresponding components in the embodiments described later. The same shall apply hereinafter in this section.

According to this configuration, in a collet for a dynamic balance tester, when the spring part is elastically deformed and the groove width of the split groove is widened with the cylindrical grip part fitted to the inner peripheral part of the test object, The grip part expands in diameter and is press-fitted into the inner peripheral part of the test object, thereby gripping the inner peripheral part. Thereby, the test object is connected to the rotating part of the dynamic balance tester so as to be integrally rotatable therewith. In this state, the rotation preventing portion provided on at least one of the gripping portion and the spring portion prevents the gripping portion and the spring portion from rotating relative to the rotating portion. Therefore, even if a large torque load is applied to the collet when the rotating part is rotated to measure the unbalance of the test object using a dynamic balance tester, the collet that has been stopped from rotating is less likely to twist. Damage can be prevented.

The rotating portion may have a tapered portion (17) having a tapered outer peripheral surface (17A) centered on the central axis (J). The gripping portion may have a tapered inner circumferential surface (22E) that can make surface contact with the outer circumferential surface of the tapered portion. The rotation preventing portion may include a first engaging portion (25) including a slit formed in the tapered inner circumferential surface.
Further, the present invention provides a dynamic balance tester (1) including the collet and the rotating part to which the collet is attached and rotates in the circumferential direction, wherein the rotation preventing part is a first engaging part. (25), the rotating part is provided with a second engaging part (26) that engages with the first engaging part in the circumferential direction.

According to this configuration, the first engaging part in the detent part of the collet and the second engaging part provided in the rotating part engage in the circumferential direction of the gripping part, that is, in the rotational direction of the rotating part. The grip part and the spring part are prevented from rotating relative to the rotating part. Therefore, damage to the collet due to torque load can be prevented as described above.
The rotating portion may have a tapered portion (17) having a tapered outer peripheral surface (17A) centered on the central axis (J). The rotation preventing portion may include a first engaging portion (25) including a slit formed in the tapered inner circumferential surface. The second engaging portion may include a protrusion inserted into the slit.

1 is a longitudinal sectional view of a main part of a dynamic balance testing machine according to an embodiment of the present invention. FIG. 2 is a view taken along arrow A in FIG. 1. FIG. 2 is a sectional view taken along the line BB in FIG. 1. FIG. It is a longitudinal cross-sectional view of the main part of the dynamic balance tester based on the modification of this invention.

Embodiments of the invention will be described in detail below. FIG. 1 is a longitudinal cross-sectional view of a dynamic balance testing machine 1. The vertical direction in FIG. 1 is the vertical direction of the dynamic balance tester 1. The left-right direction in FIG. 1 is the left-right direction of the dynamic balance tester 1. The dynamic balance testing machine 1 includes a rotating part 3 that rotates together with the test object 2, a support part (not shown) that supports the rotating part 3 in a vibrating and rotatable manner, and a motor etc. that rotationally drives the rotating part 3. It includes a drive section (not shown), a detection section (not shown) that detects vibrations of the rotating section 3 during rotation, and a collet 4 that connects the test object 2 to the rotating section 3 so as to be integrally rotatable.

The test object 2 is a rotor or the like, and a circular hole 2B bordered by an inner circumference 2A is formed in the center thereof. The hole 2B may be a through hole or a recessed portion having a bottom.

The rotating part 3 includes a cylindrical spindle 11 having a center axis J extending in the left-right direction, and a cylindrical drawbar 12 coaxially inserted into the spindle 11. The spindle 11 and the drawbar 12 are spline-coupled, for example, at their respective base sides (left side), so that they are relatively movable in the left-right direction and can rotate integrally in the circumferential direction S around the central axis J.

The spindle 11 is composed of a plurality of parts, such as a first part 13 on the base side and a second part 14 on the tip side (right side). The first part 13 has a cylindrical shape, and the second part 14 has a cylindrical shape elongated in the left-right direction. A ring-shaped flange portion 14A is provided in the middle of the second component 14 and extends outward in the radial direction R perpendicular to the central axis J. A portion of the second component 14 to the right of the flange portion 14A is a tip portion 14B, and a portion of the second component 14 to the left of the flange portion 14A is a root portion 14C. The first component 13 and the second component 14 are integrated by fixing the flange portion 14A to the right end surface of the first component 13 with bolts (not shown) or the like. In this state, the tip portion 14B protrudes to the right, and the root portion 14C is inserted into the first component 13.

The drawbar 12 includes a horizontally elongated cylindrical shaft portion 16 inserted into the inside of each of the first component 13 and the second component 14, and a tapered portion 17 coaxially connected to the right end of the shaft portion 16. . The shaft portion 16 may be divided into a plurality of parts and configured by connecting these parts. The tapered portion 17 has a truncated conical shape, and its outer circumferential surface 17A is a tapered surface that becomes larger in diameter toward the right side. The outer diameter of the left end of the outer peripheral surface 17A is larger than the outer diameter of the right end of the shaft portion 16. A groove 12A extending in the circumferential direction S is formed on the outer circumferential surface of the drawbar 12 as a boundary between the shaft portion 16 and the tapered portion 17. The tapered portion 17 protrudes to the right of the tip 14B of the spindle 11. The drawbar 12 is slidable along the central axis J relative to the spindle 11. The dynamic balance tester 1 also includes an actuator (not shown) that slides the drawbar 12.

The collet 4 is a cylindrical body arranged coaxially with the rotating part 3. The collet 4 includes an annular base part 21, a cylindrical grip part 22 fitted into the inner peripheral part 2A of the test object 2, and a plurality of spring parts installed between the base part 21 and the grip part 22. 23 is integrally included.

The base portion 21 surrounds the left end portion of the tip portion 14B of the spindle 11 while facing the flange portion 14A of the spindle 11 from the right side. By fixing the base portion 21 to the flange portion 14A via bolts B, the collet 4 is attached to the spindle 11 so as to be integrally rotatable therewith. The base portion 21 is provided with an annular protrusion 21A that borders the inner peripheral portion and protrudes to the right.

The outer diameter of the outer circumferential surface 22A of the gripping part 22 is constant over the entire area of the central part 22D between the right end 22B and the left root 22C of the gripping part 22. The tip portion 22B becomes smaller in diameter toward the right side so that it can easily fit into the inner peripheral portion 2A of the test object 2. The root portion 22C has a smaller diameter than the central portion 22D. The inner circumferential surface 22E of the gripping portion 22 is a tapered surface whose diameter increases toward the right side, and is in surface contact with the outer circumferential surface 17A of the tapered portion 17 while surrounding the tapered portion 17 of the drawbar 12.

The collet 4 is formed with a plurality of grooves 4A arranged in the circumferential direction of the gripping portion 22 (same as the circumferential direction S described above) (see FIG. 2). Each groove 4A is a slit that passes through the grip portion 22 along the radial direction (same as the radial direction R described above) and the left-right direction of the grip portion 22. In this embodiment, six grooves 4A are formed at equal intervals in the circumferential direction S, and the grip portion 22 is equally divided into six divided bodies 22F by these grooves 4A. . Each divided body 22F is a portion between the grooves 4A adjacent to each other in the circumferential direction S in the grip portion 22. The grip portion 22 can be expanded or contracted according to changes in the groove width W (see FIG. 2) of each groove 4A. Specifically, as the groove width W widens, the diameter of the gripping part 22 increases, and as the groove width W narrows, the diameter of the gripping part 22 decreases. In the dynamic balance tester 1 in a standby state, the grip portion 22 is in a reduced diameter state.

The same number of spring portions 23 as the number of grooves 4A are provided, and these spring portions 23 surround the tip portion 14B of the spindle 11 in a state where they are lined up at equal intervals in the circumferential direction S. These spring parts 23 are connected to each divided body 22F of the grip part 22 one by one. The space between the spring parts 23 adjacent in the circumferential direction S is a part of the dividing groove 4A. Each spring portion 23 is formed into a horizontally elongated rod shape. In each spring portion 23, the right end portion is connected to the root portion 22C of the grip portion 22, and the left end portion is connected to the protrusion portion 21A on the inner peripheral portion of the base portion 21. Each spring portion 23 can be elastically deformed mainly in the radial direction R using its left end portion as a fulcrum. Since the groove width W of the split groove 4A changes according to the elastic deformation of each spring portion 23, the grip portion 22 expands and contracts as described above. Specifically, when each spring portion 23 bends outward in the radial direction R, the groove width W widens, and when each spring portion 23 bends inward in the radial direction R, the groove width W narrows. In such a collet 4, the base part 21 is a fixed end, and the grip part 22 and the spring part 23 are free ends.

In the collet 4, a rotation preventing portion 24 that prevents the gripping portion 22 and the spring portion 23 from rotating relative to the rotating portion 3 is provided on at least one of the gripping portion 22 and the spring portion 23. The detent portion 24 includes a first engaging portion 25 formed on at least one of the divided bodies 22F of the grip portion 22. In this embodiment, a total of six first engaging portions 25 are provided, one for each of the divided bodies 22F. An example of the first engaging portion 25 is a slit formed by cutting out a portion of the inner peripheral portion of the divided body 22F in the left and right directions, and is exposed from the inner peripheral surface 22E of the gripping portion 22. It is also exposed from the left end surface (see also Figure 3).

In relation to the first engaging portion 25, a second engaging portion 26 is provided at the tip portion 14B of the spindle 11. An example of the second engaging portions 26 is a protrusion that protrudes to the right from the right end surface of the tip portion 14B, and is provided in the same number as the first engaging portions 25, arranged at equal intervals in the circumferential direction S, and arranged at equal intervals in the circumferential direction S. They are inserted one by one into the joints 25 from the left side. The second engaging portion 26 inserted into the first engaging portion 25 is engaged with the first engaging portion 25 in the circumferential direction S. In this state, there is a gap between the first engaging part 25 (the wall surface that partitions the slit of the first engaging part 25 in the gripping part 22) and the second engaging part 26 to the extent that the expansion and contraction of the gripping part 22 is not hindered. A slight play is ensured. By engaging the first engaging portion 25 and the second engaging portion 26, relative rotation of the gripping portion 22 and the spring portion 23 with respect to the rotating portion 3 is restricted.

When performing a dynamic balance test on the test object 2 in the dynamic balance tester 1, in preparation, the test object 2 is set on the collet 4 of the dynamic balance tester 1 in a standby state. In the collet 4 in this state, the gripping part 22 is inserted into the hole 2B of the test object 2, and the central part 22D of the gripping part 22 fits into the inner peripheral part 2A of the test object 2. The inner diameter of the inner peripheral portion 2A is slightly larger than the outer diameter of the central portion 22D of the grip portion 22 in the reduced diameter state. Therefore, the test object 2 is still held in an unclamped state by the collet 4.

Next, the aforementioned actuator (not shown) is activated to slide the drawbar 12 to the left. As a result, the tapered portion 17 of the drawbar 12 also slides to the left, and at this time, the tapered outer circumferential surface 17A of the tapered portion 17 moves leftward relative to the tapered inner circumferential surface 22E of the gripping portion 22 of the collet 4. Moving. As a result, in the collet 4, each spring portion 23 is bent outward in the radial direction R due to the force of the outer circumferential surface 17A trying to spread the inner circumferential surface 22E, thereby widening the groove width W of each split groove 4A. Therefore, the gripping portion 22 expands in diameter, and the central portion 22D of the gripping portion 22 is press-fitted into the inner peripheral portion 2A of the test object 2. At this time, the test object 2 is clamped by the inner peripheral part 2A being gripped by the gripping part 22 of the collet 4, so it can be rotated integrally with the rotating part 3 of the dynamic balance testing machine 1 via the collet 4. is connected to. Note that the inner portion in the radial direction R of the second engaging portion 26 located at the tip of the tip end 14B of the spindle 11 is received in the groove 12A of the spindle 11 with play in the left-right direction, so that it is not moved toward the left side of the drawbar 12. does not interfere with the slide.

In the dynamic balance testing machine 1 in which the test object 2 is clamped, the rotating section 3 is driven and rotated at a predetermined speed by the aforementioned drive section (not shown), and the vibration of the test object 2 in this state is detected as described above. (not shown). The unbalance of the test object 2 is obtained from the detected vibrations.

As described above, the first engaging part 25 in the rotation stopper part 24 of the collet 4 and the second engaging part 26 provided in the rotating part 3 rotate in the circumferential direction S of the gripping part 22, that is, the rotation of the rotating part 3. By engaging in this direction, the rotation preventing portion 24 prevents the grip portion 22 and the spring portion 23 from rotating with respect to the rotating portion 3 . Therefore, even if a large torque load is applied to the collet 4 when the rotating part 3 rotates to measure the unbalance of the test object 2 using the dynamic balance tester 1 (especially during acceleration/deceleration or high-speed rotation), the Since the free end of the stopped collet 4 is not easily twisted, damage to the collet 4 due to torque load can be prevented. In particular, since the influence of torsional torque acting on the spring portion 23, which has low strength in the collet 4, can be significantly reduced, damage such as breaking the spring portion 23 due to torsional torque can be prevented. Note that in order to effectively suppress twisting of the free end of the collet 4, the detent portion 24 is provided in the grip portion 22 of the collet 4, which is further away from the fixed end (base portion 21) than the spring portion 23. It is preferable.

After the dynamic balance testing machine 1 has finished measuring the unbalance of the test object 2, the aforementioned actuator (not shown) is activated to slide the drawbar 12 to the right to the original standby position. Then, in the collet 4, each spring portion 23 is bent inward in the radial direction R and restored, thereby narrowing the groove width W of each split groove 4A, so that the diameter of the gripping portion 22 is reduced. As a result, the press-fitting state of the grip portion 22 into the inner circumferential portion 2A of the test object 2 is released, and the test object 2 becomes an unclamped state. In this state, the test object 2 can be removed from the collet 4 for replacement.

This invention is not limited to the embodiments described above, and various changes can be made within the scope of the claims.

FIG. 4 is a longitudinal cross-sectional view of a main part of a dynamic balance testing machine 1 according to a modification of the present invention. In FIG. 4, parts that are functionally the same as those described in FIGS. 1 to 3 are denoted by the same reference numerals, and the description of the parts will be omitted. In the dynamic balance tester 1 according to the modified example, in the rotating part 3, the above-mentioned taper part 17 is provided not in the drawbar 12 but as part of the tip part 14B of the spindle 11, in the middle of the tip part 14B in the left-right direction. ing. The outer circumferential surface 17A of the tapered portion 17 is a tapered surface whose diameter becomes smaller toward the right side, and constitutes an intermediate region of the outer circumferential surface of the tip portion 14B. A cylindrical connecting portion 31 having a diameter one step larger than the shaft portion 16 is integrally provided at the right end portion of the drawbar 12 .

In the collet 4 according to the modification, the annular base portion 21 is located on the right side of the grip portion 22 and surrounds the connecting portion 31 of the drawbar 12. The base portion 21 has an annular flange portion 21B that extends inward in the radial direction R from the left end portion of the inner circumferential surface thereof. The flange portion 21B contacts the connecting portion 31 from the left side. A groove 21C extending in the circumferential direction S is formed at the right end of the inner peripheral surface of the base portion 21. The outer peripheral portion of the annular ring 32 is fitted into the groove 21C. The inner peripheral portion of the ring 32 contacts the connecting portion 31 from the right side. Since the connecting portion 31 is sandwiched between the flange portion 21B and the ring 32 from the left and right, the collet 4 and the drawbar 12 can integrally slide left and right. Although a chamfer 22G is formed on the right end of the outer circumferential surface 22A of the gripping portion 22 of the collet 4, the outer diameter of the entire other area is constant. The inner peripheral surface 22E of the gripping part 22 is a tapered surface whose diameter becomes smaller toward the right side, and is in surface contact with the outer peripheral surface 17A of the tapered part 17 while surrounding the tapered part 17 of the spindle 11.

The first engaging part 25 of the detent part 24 according to the modification is a slit formed by cutting out a part of the inner peripheral part of one of the divided bodies 22F in the grip part 22 to the left and right. It is exposed from the peripheral surface 22E and also from the left end surface of the grip part 22. The first engaging portion 25 may be provided in all the divided bodies 22F. The second engaging portion 26 according to the modification is a pin inserted into a hole 17B formed in the tapered portion 17 of the spindle 11. A portion of the second engaging portion 26 protruding from the hole 17B is inserted into the first engaging portion 25 from the inside in the radial direction R. Thereby, the first engaging portion 25 and the second engaging portion 26 are engaged in the circumferential direction S. Even in the modified example, a slight amount of play is ensured between the first engaging part 25 and the second engaging part 26 to the extent that expansion and contraction of the grip part 22 is not hindered.

When performing a dynamic balance test on the test object 2 in the dynamic balance tester 1 according to the modification, in preparation, the test object 2 is set on the collet 4 of the dynamic balance tester 1 in a standby state. In the collet 4 in this state, the grip portion 22 in the reduced diameter state is inserted into the hole 2B of the test object 2 and fitted into the inner circumference 2A of the test object 2. At this time, the test object 2 is still in an unclamped state while being gripped by the collet 4.

Next, the aforementioned actuator (not shown) is activated to slide the drawbar 12 to the left. As a result, the collet 4 slides to the left together with the drawbar 12, and at this time, the tapered inner circumferential surface 22E of the grip part 22 of the collet 4 is on the left side with respect to the tapered outer circumferential surface 17A of the tapered part 17 of the spindle 11. Move relative to. As a result, in the collet 4, each spring portion 23 is bent outward in the radial direction R due to the force of the outer circumferential surface 17A trying to spread the inner circumferential surface 22E, thereby widening the groove width W of each split groove 4A. Therefore, the diameter of the gripping portion 22 is expanded, and the gripping portion 22 is press-fitted into the inner peripheral portion 2A of the test object 2. At this time, the test object 2 is clamped by being gripped by the collet 4, so that it is connected via the collet 4 to the rotating part 3 of the dynamic balance tester 1 so as to be able to rotate integrally therewith. In the dynamic balance testing machine 1 in this state, the unbalance of the test object 2 is measured by driving and rotating the rotating section 3 at a predetermined speed. The second engaging portion 26 on the spindle 11 side is received by the first engaging portion 25 of the collet 4 with play in the left-right direction, so it does not prevent the drawbar 12 and the collet 4 from sliding to the left.

After the dynamic balance testing machine 1 has finished measuring the unbalance of the test object 2, the aforementioned actuator (not shown) is activated to slide the drawbar 12 and collet 4 to the right to their original standby positions. Then, in the collet 4, each spring portion 23 is bent inward in the radial direction R and restored, thereby narrowing the groove width W of each split groove 4A, so that the diameter of the gripping portion 22 is reduced. As a result, the press-fitting state of the grip portion 22 into the inner circumferential portion 2A of the test object 2 is released, and the test object 2 becomes an unclamped state. In this state, the test object 2 can be removed from the collet 4.

In the above description, the first engaging portion 25 is a slit provided in the divided body 22F, but the dividing groove 4A may be used as the first engaging portion 25. Furthermore, in the above description, the first engaging part 25 is a slit and the second engaging part 26 is a protrusion that is inserted into the first engaging part 25, but the second engaging part 26 is a slit or a protrusion that is inserted into the first engaging part 25. The first engaging portion 25 may be a protrusion instead of a groove.

In the above description, the spindle 11 and the drawbar 12 are arranged horizontally so that the central axis J of the rotating section 3 extends horizontally, but the spindle 11 and the drawbar 12 are arranged vertically so that the central axis J extends vertically. may be placed in

1 Dynamic balance tester 2 Test object 2A Inner peripheral part 3 Rotating part 4 Collet 4A Split groove 22 Gripping part 22F Divided body 23 Spring part 24 Detent part 25 First engaging part 26 Second engaging part S Circumferential direction W Groove width (of split groove 4A)

Claims (2)

In a dynamic balance testing machine , a test object is connected to a rotating part that rotates around a central axis and has a tapered part having a tapered outer peripheral surface centered on the central axis so as to be able to rotate integrally with the rotating part. Colette,
A cylindrical gripping part that has a tapered inner peripheral surface that can make surface contact with the outer peripheral surface of the tapered part, and that is fitted into the inner peripheral part of the test object and grips the inner peripheral part. , a gripping part in which a plurality of grooves are formed side by side in the circumferential direction of the gripping part, and can be expanded and contracted according to changes in the width of the grooves;
a plurality of spring portions connected one by one to portions between the grooves adjacent in the circumferential direction in the gripping portion and arranged in the circumferential direction, the plurality of spring portions being elastically deformable in order to expand and contract the gripping portion; a spring part,
a rotation preventing portion provided on the gripping portion to prevent the gripping portion and the spring portion from rotating with respect to the rotating portion ;
A collet for a dynamic balance tester , wherein the rotation preventing portion includes a first engaging portion including a slit formed in the tapered inner circumferential surface . The collet according to claim 1, and the rotating part to which the collet is attached and rotates in the circumferential direction about the central axis , the tapered part having the outer circumferential surface tapered around the central axis. A dynamic balance tester comprising : the rotating section having a section ;
The rotation prevention portion includes the first engagement portion,
The rotating part is provided with a second engaging part that includes a protrusion inserted into the slit and that engages with the first engaging part in the circumferential direction. Balance test machine.

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