Test specimen fixing device for dynamic balancing machine

Abstract

To provide an object to be tested fixing device for a dynamic balancing machine that can satisfactorily fix both a flange-like end and a sleeve-like end to a dynamic balancing machine.SOLUTION: An object to be tested fixing device 4 includes: a case 21 that has a plate-like part 21B having an insertion hole 21E; a sleeve body 22 that has a guide sleeve part 22A extending from the left side toward the right side through the insertion hole in the transverse direction with respect to the plate-like part; a plurality of chuck pawls 24 that have pawl parts 24A; and a collet 23 that is accommodated inside the guide sleeve part, and that is reduced in diameter in conjunction with a change in attitude of the plurality of chuck pawls from an open attitude S2 to a closed attitude S1. When the flange-like end 5 is fixed to a rotation part 3, an inner periphery of an opening end 32A of the collet in a reduced diameter state holds an inlay part 5D, and the pawl parts of the chuck pawls in the closed state hold a flange surface E of the flange part 5B on the left side of the plate-like part.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a test subject fixing device for fixing a test subject to a dynamic balancing machine. [Background technology]

[0002] A test specimen fixing device for fixing a test specimen to a dynamic balancing machine has been known. The test specimen fixed to the dynamic balancing machine by the test specimen fixing device is, for example, a propeller shaft. Propeller shafts include a type with flange yokes on both ends and a type with a sleeve yoke on one end and a flange yoke on the other end.

[0003] Patent Document 1 below discloses a chucking device for fixing a flange yoke to a dynamic balancing machine. This chucking device receives the spigot of the flange yoke in a receiving recess formed in a base, and then chucks the flange yoke by clamping the flange portion of the flange yoke with the claws of a pair of chuck jaws and pressing it against the base.

[0004] Furthermore, Patent Document 2 below discloses a test object fixing device that fixes a sleeve yoke to a dynamic balancing machine. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 2963725 [Patent Document 2] Patent No. 3025320 Summary of the Invention [Problem to be solved by the invention]

[0006] The type of test piece fixed to the dynamic balancing machine may be switched between a type with flange-like ends (flange yokes) on both ends and a type with a sleeve-like end (sleeve yoke) on one end and a flange-like end on the other end.

[0007] The test specimen fastening device of Patent Document 1 cannot be used to secure the sleeve-shaped end to the fastening portion of the dynamic balancing machine. Furthermore, the test specimen fastening device of Patent Document 2 cannot be used to secure the flange-shaped end to the dynamic balancing machine. Therefore, every time the type of test specimen is switched between the two types, the test specimen fastening device must be replaced as a changeover. Because this requires replacing the entire test specimen fastening device, such a changeover not only places a heavy workload on the operator performing the changeover, but also results in a time loss due to the work. In other words, the changeover cannot be performed smoothly.

[0008] Therefore, it is desirable to perform changeovers smoothly. In order to perform changeovers smoothly, the inventors of the present application have considered fixing each of the flange-shaped end and the sleeve-shaped end to the dynamic balancing machine using a common test piece fixation device (a test piece fixation device with a common main configuration). In both cases where the flange-shaped end and the sleeve-shaped end are supported, it is desirable for these ends to be well supported by the test piece fixation device. In other words, it is desirable to properly fix each of the flange-shaped end and the sleeve-shaped end to the dynamic balancing machine.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a test piece fixing device for a dynamic balancing machine that can securely fix both the flange-shaped end and the sleeve-shaped end to the dynamic balancing machine. [Means for solving the problem]

[0010] One embodiment of the present invention provides a test subject fixing device (4) for fixing a test subject (2) to a dynamic balancing machine (1). The test subject fixing device includes: a plate-shaped portion (21B) disposed opposite a rotating portion (3) of the dynamic balancing machine and spaced apart in a direction along a central axis (J) of the rotating portion, the plate-shaped portion having an insertion hole (21E); and a guide sleeve portion (22A) extending from the opposite side of the plate-shaped portion from the rotating portion, through the insertion hole, toward the rotating portion in the direction along the central axis; and a fixing portion (21, 22) fixed to the rotating portion; and a claw portion (24A) the test piece includes a plurality of chuck jaws (24) that straddle the plate-shaped portion in the direction along the central axis, the chuck jaws being capable of changing their position between a closed position (S1) in which the jaw portions approach each other and an open position (S2) in which the jaw portions are farther apart than the closed position, and a collet (23) housed inside the guide sleeve portion, the collet contracting in diameter as the chuck jaws change their position from the open position to the closed position. When a flange-shaped end (5) of a test piece, which is an end of the test piece and has a spigot portion (5D) and a flange portion (5B), is fixed to the rotating portion, the inner periphery of the open end (32A) of the collet, which has a contracted diameter as the chuck jaws change their position to the closed position, grips the spigot portion, and the jaw portions of the chuck jaws in the closed position grip a flange surface (5E) of the flange portion on the side of the plate-shaped portion opposite the rotating portion. When the sleeve-shaped end 6 of the test piece 2 having a sleeve portion 6A is fixed to the rotating portion, the outer periphery of the sleeve portion is supported by the inner periphery of the collet, which is in a contracted state as the chuck jaws change their position to the closed position. The alphanumeric characters in parentheses indicate corresponding components in the embodiments described below. The same applies hereinafter in this section.

[0011] With this configuration, when the chuck jaws are in the closed position, the collet is in a contracted state. When fixing the flanged end to the rotating part, the inner periphery of the open end of the collet in the contracted state grips the outer periphery of the spigot portion, and the jaws of the chuck jaws in the closed position grip the flange surface of the flange portion. This allows the flanged end to be fixed to the rotating part effectively.

[0012] On the other hand, when the sleeve-shaped end is fixed to the rotating part, the outer periphery of the sleeve part is supported by the inner periphery of the collet in a contracted state. This allows the sleeve-shaped end to be securely fixed to the rotating part. Therefore, both the flange-shaped end and the sleeve-shaped end can be securely fixed to the rotating part.

[0013] In one embodiment of the present invention, a plurality of first dividing grooves (23A) are formed in the open end of the collet, aligned in the circumferential direction of the collet. Further, a plurality of second dividing grooves (23B) are formed in the middle portion (32B) of the collet excluding the open end, aligned in the circumferential direction of the collet. Further, the number of the first dividing grooves is greater than the number of the second dividing grooves.

[0014] According to this configuration, the open end and intermediate portion expand and contract in accordance with changes in the groove width of each of the first and second dividing grooves. Because the number of first dividing grooves is greater than the number of second dividing grooves, the open end of the collet expands and contracts at a greater rate than the intermediate portion. Therefore, even if the inner periphery of the collet cannot simultaneously grip the spigot portion and the claw portion can simultaneously grip the flange surface, the open end of the collet expands and contracts, thereby achieving both types of gripping. This allows the flange-shaped end to be securely fixed to the rotating portion even if the flange portion of the flange-shaped end varies in thickness.

[0015] In one embodiment of the present invention, the fixed portion further includes a main body flange portion (22B) disposed on the opposite side of the plate-shaped portion from the rotating portion and connected to the guide sleeve portion. When the chuck jaws are in the closed position, the jaws abut against both the outer periphery of the main body flange portion and an opposite main surface (36) of the plate-shaped portion opposite the rotating portion.

[0016] According to this configuration, when the chuck jaws are in the closed position, the jaw portions abut against both the outer periphery and the opposite main surface of the body flange portion. When the chuck jaws are in the closed position, two points of the jaw portions abut against the fixing portion. Therefore, even if the jaw portions do not abut against the workpiece (sleeve-shaped end portion) to be supported, the jaw portions do not become free. In other words, even if the workpiece to be supported is a sleeve-shaped end portion, the jaw portions can be prevented from becoming free. This allows the dynamic balancing machine to maintain good unbalance measurement accuracy when the sleeve-shaped end portion is supported by the test specimen fixing device. In this case, the dynamic balancing machine can maintain good unbalance measurement accuracy. [Brief explanation of the drawings]

[0017] [Figure 1A] 1A is a longitudinal sectional view of a main part of a dynamic balancing machine including a test specimen fastening device according to one embodiment of the present invention, showing the clamped state of the test specimen fastening device when supporting a flange-shaped end portion. [Figure 1B] FIG. 1B is a schematic cross-sectional view for explaining the actuator of the dynamic balancing machine. [Figure 1C] FIG. 1C is a schematic cross-sectional view for explaining the actuator of the dynamic balancing machine. [Figure 2] FIG. 2 is a schematic view of the test subject fixing device as seen from above. [Figure 3] FIG. 3 is a schematic diagram of the test subject fixing device as seen from the left side. [Figure 4] FIG. 4 is an enlarged view of a main part of FIG. 1A. [Figure 5]FIG. 5 is a perspective view of the collet shown in FIG. 1A. [Figure 6] FIG. 6 is a vertical cross-sectional view of the main part of the dynamic balancing machine, showing the unclamped state when the flange-like end is supported. [Figure 7] FIG. 7 is a longitudinal sectional view of the dynamic balancing machine showing the clamping state when supporting the sleeve-shaped end portion. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of the present invention will be described in detail below. Fig. 1A is a longitudinal sectional view of a main part of a dynamic balancing machine 1 including a test specimen fastening device 4 according to one embodiment of the present invention. Figs. 1B and 1C are schematic sectional views for explaining an actuator of the dynamic balancing machine. Fig. 2 is a view of the test specimen fastening device 4 as seen from above. Fig. 3 is a view of the test specimen fastening device 4 as seen from the left side. Fig. 4 is an enlarged view of a main part of Fig. 1A. The dynamic balancing machine 1 will be described mainly with reference to Fig. 1A. Figs. 2 to 4 will be referenced as appropriate.

[0019] 1A shows the clamped state of the specimen holding device 4 when supporting the flange-like end portion 5. The up-down direction in FIG. 1A is the up-down direction of the dynamic balancing machine 1. The left-right direction in FIG. 1A is the left-right direction of the dynamic balancing machine 1. The dynamic balancing machine 1 includes a rotating unit 3 that rotates together with the specimen 2, a support unit (not shown) that supports the rotating unit 3 so that it can vibrate and rotate, a drive unit (not shown) such as a motor that drives the rotating unit 3 to rotate, a detection unit (not shown) that detects vibrations of the rotating unit 3 during rotation, and the specimen holding device 4. The specimen holding device 4 supports the end portion of the specimen 2 and is connected to the rotating unit 3 so that it can rotate integrally with the rotating unit 3.

[0020] An example of the specimen 2 under test is a propeller shaft. This type of specimen 2 can be classified into a type with flange yokes at both one end and the other end, and a type with a sleeve yoke at one end and a flange yoke at the other end. The specimen holding device 4 supports one end of the specimen 2 under test, regardless of whether that end is a flange-shaped end (with a flange yoke) 5 or a sleeve-shaped end (with a sleeve yoke) 6 (see FIG. 7). The dynamic balancing machine 1 includes a rotating unit 3 and a pair of specimen holding devices 4 to support one end of the specimen 2 under test. The other end (flange-shaped end) of the specimen 2 is fixed to a rotating unit and a specimen holding device different from the rotating unit 3 and the specimen holding device 4. However, the dynamic balancing machine 1 may include two pairs of rotating units 3 and specimen holding devices 4, and the other end of the specimen 2 may also be fixed to the rotating unit 3 and the specimen holding device 4. That is, the other end of the test specimen 2 may also be supported by the test specimen holding device 4. Of course, when the test specimen 2 is not supported at both ends (when it is supported at one end), the dynamic balancing machine 1 will only include one pair of rotating section 3 and test specimen holding device 4. In FIG. 1A, the end of the test specimen 2 supported by the test specimen holding device 4 is one end of the test specimen 2, and this one end is shown as a flange-shaped end 5.

[0021] As shown in FIG. 1A, the flange-like end portion 5 integrally comprises a cylindrical main body portion 5A and a flange portion 5B that protrudes from the outer periphery of the cylindrical main body portion 5A in a radial direction R perpendicular to the central axis J (described below). The cylindrical main body portion 5A and the flange portion 5B are coaxial with each other. A cylindrical protrusion 5C that protrudes one level to the right from the right surface of the flange portion 5B is formed at the right end of the cylindrical main body portion 5A, and a spigot portion 5D that serves as a rotation reference for the flange-like end portion 5 is formed on the outer periphery of the cylindrical protrusion 5C. The left surface of the flange portion 5B is a flange surface 5E. The outer periphery 5F of the flange portion 5B is a cylindrical surface. A pin insertion hole is formed in the flange portion 5B, penetrating the flange portion 5B in a direction along the central axis J (left-right direction). Multiple pin insertion holes are formed. The multiple pin insertion holes are formed at multiple positions equally spaced apart in the circumferential direction S.

[0022] 1A, the rotating unit 3 includes a cylindrical spindle 11 having a central axis J extending in the left-right direction, and a columnar drawbar 12 arranged coaxially within the spindle 11. The spindle 11 and the drawbar 12 are connected, for example, by a spline, so that the drawbar 12 is slidable relative to the spindle 11 in the left-right direction along the central axis J and is rotatable integrally with the shaft portion of the spindle 11 (including a first part 13 and a second part 14, which will be described below) in the circumferential direction S around the central axis J. As shown in FIG. 1B, the dynamic balancing machine 1 also includes an actuator 100 that slides the drawbar 12.

[0023] The spindle 11 includes multiple parts, such as a cylindrical first part 13 that forms the main body of the spindle 11, and an annular second part 14 that is coaxially fixed to the first part 13 with bolts (not shown). The drawbar 12 may also be configured with multiple parts. As shown in FIG. 1B, the spindle 11 further includes a rotating shaft 11A and a housing 11B. The rotating shaft 11A is connected to the first part 13 and the second part 14 so as to be rotatable together.

[0024] The actuator 100 includes a pressure plate 101 fixed to the base end of the draw bar 12, a spring member 102 that biases the pressure plate 101 to the right, an air spring 103, and a compressed gas supply unit (not shown) that supplies compressed gas to the inside of the air spring 103. The spring member 102 is, for example, a disc spring. The air spring 103 is disposed between the pressure plate 101 and a bracket 104 on the main body of the dynamic balancing machine 1. The air spring 103 has a known structure that includes a bellows. For example, a Sumimount (trademark: manufactured by Sumitomo Electric Industries, Ltd.) is used as the air spring 103.

[0025] The actuator 100 further includes a guide member 105 interposed between the pressure plate 101 and the air spring 103. The guide member 105 is in sliding contact with the pressure plate 101. The guide member 105 does not rotate in conjunction with the rotation of the draw bar 12 and the pressure plate 101.

[0026] The actuator 100 further includes a spring case 106 that houses the spring member 102. The spring case 106 rotates in conjunction with the rotation of the rotary shaft 11A. The spring case 106 is provided with a pair of moving parts 107A, 107B that can move toward and away from each other in the left-right direction. The left moving part 107A is fixed to the rotary shaft 11A, and the right moving part 107B is in sliding contact with the guide member 105. The spring member 102 is housed between the pair of moving parts 107A, 107B, which are fixed to the rotary shaft 11A.

[0027] The actuator 100 further includes a guide member 105 interposed between the pressure plate 101 and the air spring 103. The guide member 105 is in sliding contact with the pressure plate 101. The guide member 105 does not rotate in conjunction with the rotation of the draw bar 12 and the pressure plate 101.

[0028] When compressed air is not supplied to the air spring 103, as shown in FIG. 2, the pressure plate 101 pressed by the spring member 102 slides to the right, and the drawbar 12 retreats to the right.

[0029] When compressed air is supplied to the air spring 103, the air spring 103 expands in the left-right direction, and the pressure plate 101 slides to the left against the spring force of the spring member 102, as shown in Fig. 3. The draw bar 12 slides along with the pressure plate 101. In the state shown in Fig. 3, the draw bar 12 is advanced further to the left than the position shown in Fig. 3.

[0030] In the actuator 100, the compressed gas supply unit switches between supplying and stopping the supply of compressed gas to the inside of the air spring 103. This allows switching between a state in which the draw bar 12 advances to the left (see FIG. 2) and a state in which the draw bar 12 retreats to the right (see FIG. 3). In other words, the actuator 100 functions as a switching device that switches the test subject fixing device 4 between a clamped state and an unclamped state.

[0031] As shown in FIG. 1A, the test specimen fixture 4 is attached to the rotating unit 3 from the left side. As shown in FIGS. 1A and 2, the test specimen fixture 4 includes a case 21 fixed to the spindle 11, a sleeve body 22 fixed to the case 21, a collet 23 disposed within the sleeve body 22, multiple (two in this embodiment) chuck jaws 24, and a driving member 25 that drives the clamping operations of the multiple chuck jaws 24 and the collet 23. The case 21 and the sleeve body 22 are provided on the fixed unit. The driving member 25 changes the position of the multiple chuck jaws 24 between a closed position S1 (the position shown in FIG. 1A) and an open position S2 (the position shown in FIG. 6). The test specimen fixture 4 may further include an inner collet 61 (see FIG. 7) that is detachably fixed within the collet 23.

[0032] 1A and 2, the case 21 includes a cylindrical body 21A (see FIG. 2) arranged coaxially with the spindle 11, and a disk-shaped plate-like portion 21B arranged coaxially with the spindle 11 at the left end of the body 21A. The body 21A and the plate-like portion 21B may be integrally formed, or may be separate components that are later combined with each other. Note that the moving shaft 41 and the tip fitting 43 are not shown in FIG. 2.

[0033] 2, the body 21A includes a pair of arc-shaped portions 21C facing each other in a direction perpendicular to the plane of the drawing. The pair of arc-shaped portions 21C are arranged at a distance from each other in the circumferential direction (the same as the circumferential direction S) of the case 21. A long opening extending in the left-right direction is formed between both ends of one arc-shaped portion 21C in the circumferential direction S and both ends of the other arc-shaped portion 21C in the circumferential direction S. The right end of each arc-shaped portion 21C is fixed to the spindle 11 by a bolt (not shown).

[0034] As shown in FIG. 1A, the plate-shaped portion 21B is disposed opposite the rotating portion 3 at a predetermined distance to the left. An insertion hole 21E is formed in the center of the plate-shaped portion 21B, penetrating the plate-shaped portion 21B in the left-right direction. The insertion hole 21E is circular. At a plurality of positions on the plate-shaped portion 21B that are equally spaced apart in the circumferential direction S (two positions in this embodiment that are 180 degrees apart), one through hole 21F is formed, penetrating the plate-shaped portion 21B in the left-right direction. The through hole 21F is rectangular when viewed from the left-right direction.

[0035] As shown in FIG. 1A, the left surface of plate-shaped portion 21B is an opposite main surface 36 on the opposite side of plate-shaped portion 21B from rotating portion 3. On opposite main surface 36, an accommodating recess 37 is formed on an imaginary line connecting the central axis of plate-shaped portion 21B (the same as central axis J) and the plurality of through holes 21F. Accommodating recess 37 may be a groove as shown in FIG. 4, or may be a through hole penetrating plate-shaped portion 21B in the left-right direction. A pressing member 38 is accommodated in accommodating recess 37.

[0036] As shown in Fig. 4, the pressing members 38 correspond one-to-one to the individual chuck jaws 24. The pressing members 38 include a contact pin 39, an elastic pressing portion 40, and a fixed portion 40A fixed to the right surface of the plate-shaped portion 21B from the right side. The contact pin 39 is movable in the left-right direction. The contact pin 39 is integrally provided with a tip portion 39A having a hemispherical tip that contacts the toe portion 52 of the chuck jaw 24, an intermediate portion 39B having a larger diameter than the tip portion 39A, and a base end portion 39C having a smaller diameter than the intermediate portion 39B.

[0037] The elastic pressing portion 40 is, for example, a spring member, more specifically, a disc spring. The elastic pressing portion 40 is interposed between the left end surface of the fixed portion 40A and the intermediate portion 39B. The elastic pressing portion 40 surrounds the periphery of the base end portion 39C. The abutment pin 39 is elastically pressed toward the left by the elastic pressing portion 40. When the chuck jaws 24 are in the closed position S1, the tip of a positioning protrusion 53 of a jaw portion 24A (described later) of the chuck jaws 24 abuts against the tip portion 39A of the abutment pin 39 from the left side.

[0038] 1A, the sleeve body 22 integrally comprises a cylindrical guide sleeve portion 22A, a disk-shaped body flange portion 22B that projects outward from the left end of the guide sleeve portion 22A in the radial direction of the sleeve body 22 (the same as the radial direction R), and a disk-shaped tip surface portion 22C that forms the right end surface of the guide sleeve portion 22A. The guide sleeve portion 22A and the body flange portion 22B are arranged coaxially with the spindle 11. The inner peripheral surface 22E of the guide sleeve portion 22A is a tapered surface whose diameter decreases toward the right. The outer peripheral surface of the guide sleeve portion 22A is a cylindrical surface with a substantially constant outer diameter.

[0039] The main body flange portion 22B is fixed to the plate-shaped portion 21B from the left side by a plurality of bolts B1 (see FIG. 3). The left surface of the main body flange portion 22B is a flange surface 22G on the opposite side of the main body flange portion 22B from the rotating portion 3. The outer peripheral surface 22H of the main body flange portion 22B is a cylindrical surface.

[0040] As shown in FIG. 3, grooves 22J recessed inward in the radial direction R are formed on the outer peripheral surface 22H of the main body flange portion 22B at a plurality of positions (the same number as the chuck jaws 24) (two positions offset by 180 degrees in this embodiment) equally spaced apart in the circumferential direction (same as the circumferential direction S) of the sleeve main body 22. The grooves 22J fit into the jaw main body portions 51 of the jaw portions 24A of the chuck jaws 24 when the chuck jaws 24 are in the closed position S1. A plurality of bolt insertion holes 22K are formed penetrating the main body flange portion 22B in the left-right direction. Bolts B1 are inserted into the bolt insertion holes 22K. A plurality of positioning pins 22L protruding toward the side opposite the rotating portion 3 are formed on the flange surface 22G. The positioning pins 22L are arranged at a plurality of positions (four positions offset by 90 degrees in this embodiment) equally spaced apart in the circumferential direction S.

[0041] 1A, a circular through-hole 22D is defined by the inner peripheral end surface of the tip surface portion 22C. The through-hole 22D passes through the right end surface of the guide sleeve portion 22A in the left-right direction. The through-hole 22D is circular and formed coaxially with the drawbar 12.

[0042] FIG. 5 is a perspective view of the collet 23. The configuration of the collet 23 will be described with reference to FIGS. 1A and 5. The collet 23 is a cylindrical body arranged coaxially with the spindle 11. The collet 23 integrally includes a disk-shaped base portion 31 and a cylindrical gripping portion 32 into which the cylindrical protrusion 5C of the flange-shaped end portion 5 and the inner collet 61 (see FIG. 7) are selectively inserted. In the collet 23, the base portion 31 is the fixed end, and the gripping portion 32 is the free end. The gripping portion 32 has an open end portion 32A, which is the left end, and an intermediate portion 32B between the open end portion 32A and the base portion 31. Engagement pins 32D (not shown in FIG. 5; see FIG. 3) are arranged on the open end surface 23C of the collet 23 (see also FIG. 3) at multiple positions equally spaced apart in the circumferential direction S (two positions 180 degrees apart in this embodiment).

[0043] The inner peripheral surface of the disk-shaped base portion 31 is bordered by a circular through-hole 31A that penetrates the center of the base portion 31 in the left-right direction. The through-hole 31A is formed coaxially with the drawbar 12. The through-hole 31A is adjacent to the through-hole 22D in the left-right direction, and when viewed from the left, the through-hole 31A overlaps with the through-hole 22D. An annular step 31B that is continuous with the inner surface (left side surface) of the base portion 31 is formed on the inner peripheral surface of the base portion 31. An engaging portion 43B of the tip fitting 43, which will be described later, engages with the annular step 31B.

[0044] As shown in FIG. 5, the open end 32A of the gripping portion 32 is formed with a plurality of first dividing grooves 23A (not shown in FIG. 3) aligned in the circumferential direction of the collet 23 (the same as the circumferential direction S described above). The first dividing grooves 23A are slits that penetrate the open end 32A along the radial direction (the same as the radial direction R) and the left-right direction of the collet 23. In this embodiment, 18 first dividing grooves 23A are formed aligned at equal intervals in the circumferential direction S. The right end of each of the first dividing grooves 23A forms a circular hole. The open end 32A can expand and contract depending on the change in the groove width of each of the first dividing grooves 23A. As the groove width of the first dividing grooves 23A expands, the diameter of the open end 32A expands, and as the groove width of the first dividing grooves 23A narrows, the diameter of the open end 32A narrows.

[0045] As shown in FIG. 5, a plurality of second division grooves 23B are formed in the middle portion 32B of the grip portion 32 and are aligned in the circumferential direction S. The second division grooves 23B are slits that penetrate the middle portion 32B in the radial direction R and the left-right direction. In this embodiment, six second division grooves 23B are formed and aligned at equal intervals in the circumferential direction S. The right end of each second division groove 23B is a round hole. The middle portion 32B can expand and contract according to changes in the groove width of each second division groove 23B. As the groove width of the second division grooves 23B expands, the diameter of the middle portion 32B expands, and as the groove width of the second division grooves 23B narrows, the diameter of the middle portion 32B contracts.

[0046] Since the number of first dividing grooves 23A is greater than the number of second dividing grooves 23B, in the gripping portion 32 of the collet 23, the opening end 32A expands and contracts at a rate of change greater than that of the intermediate portion 32B.

[0047] The outer peripheral surface 32C of the grip portion 32 is a tapered surface that increases in diameter toward the left. The inner peripheral surface of the grip portion 32 is a cylindrical surface with a substantially constant inner diameter.

[0048] 1A and 3, a plurality of chuck jaws 24 (two in this embodiment) are arranged at a plurality of positions (two positions 180 degrees apart in this embodiment) spaced apart at equal intervals in the circumferential direction S. As shown in FIG. 1A, the base end of each chuck jaw 24 is connected to a second pin 45F (described later) of the drive member 25. In conjunction with the left-right sliding of the moving part 42 of the drive member 25, the chuck jaws 24 swing around the second pin 45F as a swing axis and change their position. Each chuck jaw 24 changes its position between a closed position S1 and an open position S2 (see FIG. 6).

[0049] The chuck jaws 24 include a claw portion 24A located at the tip end, a connecting portion 24B located at the base end, and a long connecting portion 24C connecting the claw portion 24A and the connecting portion 24B. The connecting portion 24B is swingably connected to the second pin 45F. The chuck jaws 24 are inserted through the through-hole 21F and straddle the plate-shaped portion 21B in the left-right direction. In the chuck jaws 24, the claw portion 24A is located on the left side of the plate-shaped portion 21B, and the connecting portion 24B is located on the right side of the plate-shaped portion 21B.

[0050] As shown in FIG. 1A , the claw portion 24A integrally includes a claw body 51 extending in the direction of extension of the connecting portion 24C, a claw toe 52 protruding inward in the radial direction R from the tip of the claw body 51, and a positioning protrusion 53 protruding toward the base end from the end face of the claw body 51 on the base end side of the chuck claw 24. A first abutment surface 54 and a second abutment surface 55, both of which are flat, are formed on the end face of the claw toe 52 on the base end side of the chuck claw 24 and on the inner end face of the claw body 51 in the radial direction R. The first abutment surface 54 abuts against a flange surface 5E of the flange-like end 5 of the test specimen 2 supported by the test specimen fixing device 4. The tip of the positioning protrusion 53 abuts against a corresponding abutment pin 39 of a pressing member 38 disposed on the opposite main surface 36 of the plate-shaped portion 21B.

[0051] The driving member 25 includes a moving shaft 41, a moving section 42 to which the base ends of the multiple chuck jaws 24 are connected, and a tip fitting 43 that engages with the collet 23. The moving section 42 is connected to the moving shaft 41 so as to be movable together with the moving shaft 41. The tip fitting 43 is fixed to the moving shaft 41.

[0052] The moving shaft 41 has a cylindrical portion 41A arranged coaxially with the drawbar 12 and a spherical portion 41B provided on the outer peripheral surface of the cylindrical portion 41A midway in the left-right direction. The cylindrical portion 41A is fixed to the left end of the drawbar 12 by a bolt B2 inserted therein. This allows the entire moving shaft 41 to slide left and right together with the drawbar 12. The sliding range of the moving shaft 41 in the left-right direction is, for example, several tens of millimeters. The right end of the sliding range of the moving shaft 41 is referred to as the retracted position, and the left end of the sliding range of the moving shaft 41 is referred to as the advanced position. The moving shaft 41 shown in FIG. 1A is in the retracted position. The sliding distance between the moving shaft 41 in the retracted position and the advanced position (the position of the moving shaft 41 shown in FIG. 6, which will be described later) is, for example, approximately 16 mm. A groove 41C that accommodates a portion of the tip fitting 43 is formed in the left end surface of the moving shaft 41.

[0053] The moving portion 42 includes a disk-shaped disk portion 44, a ring-shaped ring portion 45, and a plurality of connecting bars 46 (the same number as the chuck jaws 24) that connect the disk portion 44 and the ring portion 45 together.

[0054] The disk portion 44 is disposed so as to surround the outer periphery of the moving shaft 41. An inner peripheral surface 44D of the disk portion 44 is bordered by a through-hole 44A that penetrates the center of the disk portion 44 in the left-right direction. The through-hole 44A has a circular shape formed coaxially with the moving shaft 41. The inner peripheral surface 44D is an arcuate surface with approximately the same curvature as the spherical surface 41B of the moving shaft 41 and is in surface contact with the spherical surface 41B while surrounding the spherical surface 41B. Due to the concave-convex engagement between the inner peripheral surface 44D and the spherical surface 41B, the disk portion 44 can slide left-right together with the drawbar 12 and the moving shaft 41. Furthermore, due to the spherical engagement between the inner peripheral surface 44D and the spherical surface 41B, the disk portion 44 can displace along the spherical surface 41B. This displacement allows the disk portion 44 to slightly change its position relative to the moving shaft 41.

[0055] On the outer periphery of the disk portion 44, first pins 44B are arranged along the circumferential direction S at a plurality of positions (two positions 180 degrees apart in this embodiment) that are equally spaced apart in the circumferential direction S. Specifically, on the outer periphery of the disk portion 44, pin support portions 44C protrude outward in the radial direction R from the plurality of positions, and both ends of the first pin 44B are supported by these pairs of pin support portions 44C.

[0056] The ring portion 45 is disposed to surround the outer periphery of the guide sleeve portion 22A of the sleeve main body 22. The ring portion 45 includes an inner ring 45A and an outer ring 45B that fit together. The inner circumferential surface of the inner ring 45A is a sliding contact surface 45C that slides against the outer circumferential surface of the guide sleeve portion 22A. The outer circumferential surface of the inner ring 45A includes a spherical portion 45D. The inner circumferential surface 45E of the outer ring 45B is an arcuate surface with substantially the same curvature as the spherical portion 45D of the inner ring 45A. The inner circumferential surface 45E of the outer ring 45B is in surface contact with the spherical portion 45D while surrounding it. Due to the spherical engagement between the inner circumferential surface 45E and the spherical portion 45D, the outer ring 45B is connected to the inner ring 45A so as to be displaceable along the spherical portion 45D. This allows the outer ring 45B to slightly change its position relative to the guide sleeve portion 22A of the sleeve body 22. In addition, the guide sleeve portion 22A of the sleeve body 22 can slide on the inner periphery of the ring portion 45.

[0057] On the outer periphery of the outer ring 45B, second pins 45F are arranged at a plurality of positions (two positions 180 degrees apart in this embodiment) spaced apart at equal intervals in the circumferential direction S, along the circumferential direction S. Specifically, pin support portions 45G protrude outward in the radial direction R from the plurality of positions on the outer periphery of the outer ring 45B, and both ends of the second pin 45F are supported by a pair of pin support portions 45G. The plurality of second pins 45F correspond one-to-one to the plurality of first pins 44B. The corresponding first pins 44B and second pins 45F are parallel to each other. The second pins 45F are pivot axes of the chuck jaws 24.

[0058] The connecting bar 46 connects the disk portion 44 and the ring portion 45 so that they can move together in the left-right direction. The connecting bar 46 has one end and the other end. One end of the connecting bar 46 is swingably connected to the first pin 44B. The other end of the connecting bar 46 is swingably connected to the second pin 45F. As the connecting bars 46 swing, the relative position of the disk portion 44 and the ring portion 45 can be slightly changed.

[0059] The tip fitting 43 integrally includes a cylindrical shaft portion 43A arranged coaxially with the drawbar 12 and a ring-shaped engaging portion 43B that protrudes from the outer periphery of the left end portion of the shaft portion 43A in the circumferential direction of the moving shaft 41 (the same as the circumferential direction S). The shaft portion 43A of the tip fitting 43 is housed in the groove 41C. As described above, the tip fitting 43 is fixed to the moving shaft 41.

[0060] 6 is a longitudinal cross-sectional view of the main parts of the dynamic balancing machine 1, showing the unclamped state when supporting the flanged end 5. A case will be described where the flanged end 5 is supported by the test specimen fixing device 4 and a dynamic balancing test is performed on the test specimen 2 in the dynamic balancing machine 1. In preparation for this dynamic balancing test, the flanged end 5 is set from the left side onto the main body flange portion 22B (sleeve main body 22) and collet 23 of the test specimen fixing device 4 in the unclamped state.

[0061] 6, in the unclamped state of the test specimen fixing device 4, the moving shaft 41 is in the advanced position, and the engaging portion 43B of the tip fitting 43 is spaced apart to the left from the annular step portion 31B of the base portion 31 of the collet 23. Therefore, the tip fitting 43 does not engage with the annular step portion 31B. In this state, the chuck jaws 24 are in the open position S2, and the gripping portion 32 of the collet 23 is in a non-diameter-reduced state (diameter-expanded state).

[0062] Because each chuck jaw 24 is in the open position S2, each jaw 24A is retracted so as not to interfere with the test piece 2 set in the collet 23. When the flange-shaped end 5 is set in the collet 23, the outer circumferential surface of the cylindrical protrusion 5C of the flange-shaped end 5 fits into the inner periphery of the open end 32A of the collet 23. The flange-shaped end 5 is positioned in the circumferential direction S by inserting multiple positioning pins 22L of the body flange portion 22B of the sleeve body 22 into multiple pin insertion holes (not shown) formed in the flange-shaped end 5. Because the outer diameter of the outer circumferential surface of the cylindrical protrusion 5C of the flange-shaped end 5 is slightly smaller than the inner diameter of the open end 32A of the collet 23 in the non-reduced state, the flange-shaped end 5 is not clamped by the open end 32A in this state.

[0063] Next, the actuator 100 described above is activated to slide the drawbar 12 to the right. As a result, the movable shaft 41, which had been in the advanced position until then, slides to the right together with the drawbar 12 toward the retracted position (see FIG. 1A). In conjunction with the sliding of the movable shaft 41, the disk portion 44 and the ring portion 45 slide to the right. As the movable shaft 41 slides, the tip fitting 43 also slides to the right, and eventually the engaging portion 43B of the tip fitting 43 engages with the annular step portion 31B of the base portion 31.

[0064] After the end fitting 43 and the annular step portion 31B are engaged, if the movable shaft 41 is further slid to the right, the collet 23 slides to the right in accordance with the sliding of the movable shaft 41. That is, the collet 23 slides to the right relative to the guide sleeve portion 22A of the sleeve body 22. At this time, the tapered inner circumferential surface 22E of the guide sleeve portion 22A moves to the left relative to the tapered outer circumferential surface 32C of the gripping portion 32 of the collet 23. Then, in the collet 23, the inner circumferential surface 22E is deflected inward in the radial direction R by a force that compresses the outer circumferential surface 32C, thereby narrowing the groove widths of the first dividing grooves 23A and the second dividing grooves 23B. As a result, the diameter of the gripping portion 32 is reduced. When the moving shaft 41 has moved to the retracted position (see FIG. 1A), the gripping portion 32 is sufficiently reduced in diameter, and in this state, the inner periphery of the opening end 32A of the gripping portion 32 in the reduced diameter state grips the spigot portion 5D.

[0065] Additionally, as the disk portion 44 and the ring portion 45 slide to the right in conjunction with the sliding of the movable shaft 41, the plurality of second pins 45F slide to the right. When the second pins 45F slide, the posture of the corresponding chuck jaws 24 changes. Specifically, as the corresponding second pins 45F slide, the connecting portions 24C of the chuck jaws 24 are guided by the peripheral wall of the insertion hole 21E, and the posture of each chuck jaw 24 changes so that it closes (the jaw portions 24A approach the central axis J). That is, as the movable shaft 41 slides to the right, each chuck jaw 24 closes.

[0066] When the moving shaft 41 has moved to the retracted position (see FIG. 1A), each chuck jaw 24 assumes the closed position S1. When each chuck jaw 24 is in the closed position S1, the flange portion 5B is sandwiched between the jaws 24A and pressed against the sleeve body 22. Specifically, the first abutment surface 54 of the claw tip 52 of each jaw 24A abuts against the flange surface 5E of the flange portion 5B. When each chuck jaw 24 is in the closed position S1, the second abutment surface 55 of the jaw body 51 of each jaw 24A abuts against both the outer peripheral surface 5F of the flange portion 5B and the bottom wall of the recessed groove 22J of the body flange 22B. When each chuck jaw 24 is in the closed position S1, the tip of the positioning protrusion 53 of each jaw 24A abuts against the abutment pin 39 of the pressing member 38 disposed on the left surface of the plate-shaped portion 21B.

[0067] As described above, when movable shaft 41 has moved to the retracted position (see FIG. 1A), the inner peripheral surface of open end 32A of collet 23, which is in a reduced diameter state, grips spigot portion 5D. Also, in this state, claws 24A of chuck claws 24, which are in closed position S1, grip flange surface 5E of flange portion 5B. That is, flange-shaped end 5 is clamped by both spigot portion 5D and flange surface 5E.

[0068] In the dynamic balancing machine 1 with the flange-like end 5 clamped, the rotating unit 3 is driven and rotated at a predetermined speed (for example, 4000 rpm) by the driving unit (not shown) described above, and the vibration of the test piece 2 in this state is detected by the detecting unit (not shown) described above. The detected vibration gives the unbalance of the test piece 2. The spigot portion 5D, which is the rotation reference of the flange-like end 5, is gripped by the inner periphery of the open end 32A of the collet 23, so the rotation reference of the flange-like end 5 can be maintained with high precision.

[0069] When clamping a flange-like end portion 5, if there is variation in the thickness of the flange portion 5B of the flange-like end portion 5 to be clamped, the variation in thickness may prevent the inner periphery of the opening end 32A of the collet 23 from gripping the spigot portion 5D and the claw portions 24A from gripping the flange surface 5E simultaneously. Specifically, the claw portions 24A may grip the flange surface 5E before the inner periphery of the opening end 32A grips the spigot portion 5D. Conversely, the inner periphery of the opening end 32A may grip the spigot portion 5D before the claw portions 24A grip the flange surface 5E. In these cases, if the opening end 32A does not expand or contract or the rate of expansion or contraction is small, only one of gripping the flange surface 5E by the claw portions 24A and gripping the spigot portion 5D by the inner periphery of the opening end 32A may be achieved, and the other may not be achieved. In this case, the accuracy of measuring the imbalance may be reduced.

[0070] However, in this embodiment, the open end 32A of the collet 23 expands and contracts at a greater rate than the intermediate portion 32B. That is, the diameter of the open end 32A expands and contracts more significantly. Therefore, even if the inner periphery of the collet 23 cannot simultaneously grip the spigot portion 5D and the claw portions 24A cannot simultaneously grip the flange surface 5E, the expansion and contraction of the open end 32A of the collet 23 allows both to be gripped. This allows the flange-shaped end 5 to be securely fixed to the rotating portion 3 even if there is variation in the thickness of the flange portion 5B of the flange-shaped end 5.

[0071] After measuring the unbalance of the test specimen 2, the dynamic balancing machine 1 activates the actuator described above to slide the drawbar 12 to the left to its original extended position (see FIG. 6). In response, the movable shaft 41, which was previously in the retracted position, slides leftward together with the drawbar 12 toward the extended position (see FIG. 6). As the movable shaft 41 slides, the end fitting 43 slides leftward, and the collet 23 also slides leftward. With the collet 23 returned to the extended position (see FIG. 6), the end fitting 43 further slides leftward, thereby disengaging the end fitting 43 from the annular step portion 31B. With the collet 23 returned to the extended position, the gripping portion 32 is in a non-reduced diameter state (expanded diameter state). Furthermore, as the movable shaft 41 slides, the movable portion 42 slides leftward, and the chuck jaws 24, which were in the closed position S1, move to the open position S2. As a result, the gripping of the spigot portion 5D and the flange surface 5E is released. That is, the clamped state of the flange-shaped end portion 5 is released.

[0072] Next, a case where the sleeve-shaped end portion 6 is supported by the test object fixing device 4 and a dynamic balancing test of the test object 2 in the dynamic balancing machine 1 will be described.

[0073] 7 is a vertical cross-sectional view of the dynamic balancing machine 1, showing the clamped state when supporting the sleeve-shaped end portion 6. The sleeve-shaped end portion 6 has a cylindrical sleeve portion 6A. The outer peripheral surface 6B of the sleeve portion 6A serves as the rotation reference for the sleeve-shaped end portion 6.

[0074] The test specimen fixing device 4 further includes an inner collet 61 that is detachably fixed within the collet 23. When the support object is the sleeve-shaped end portion 6, the inner collet 61 is attached within the collet 23, and the sleeve-shaped end portion 6 is supported within the inner collet 61.

[0075] The inner collet 61 integrally comprises a cylindrical portion 61A and a flange portion 61B. The inner collet 61 is a cylindrical body arranged coaxially with the collet 23. The cylindrical portion 61A is formed with a plurality of split grooves 61C (only one of which is shown in FIG. 7 ) aligned in the circumferential direction of the inner collet 61 (the same as the circumferential direction S described above). These split grooves penetrate the entire region of the cylindrical portion 61A in the radial and left-right directions of the inner collet 61, excluding the right end portion. These multiple split grooves are also formed in the cylindrical portion 61A. The inner peripheral ends of the split grooves in the flange portion 61B are connected to the left ends of the multiple split grooves in the cylindrical portion 61A. The split grooves in the flange portion 61B penetrate the flange portion 61B in the radial and left-right directions of the flange portion 61B. Note that multiple types of inner collets 61 are prepared depending on the type of sleeve-shaped end portion 6 supported by the test specimen fixing device 4.

[0076] In preparation for a dynamic balancing test in the dynamic balancing machine 1, the inner collet 61 is inserted into the inner periphery of the collet 23 of the test specimen fixing device 4 in an unclamped state. At this time, the circumferential position S of the inner collet 61 is adjusted so that the engagement pins 32D fit into multiple circumferential elongated holes (not shown) formed in the cylindrical portion 61A. Then, by rotating the inner collet 61 by a predetermined amount after insertion, the engagement pins 32D engage with the engagement positions of the circumferential elongated holes (not shown), thereby preventing the inner collet 61 from coming off. In this state, the inner collet 61 is fixed to the sleeve body 22 and the collet 23. Then, the sleeve-shaped end portion 6 is set into the inner collet 61 from the left side.

[0077] As described above, in the unclamped state of the test specimen fixing device 4, the moving shaft 41 is in the advanced position, and the gripping portion 32 of the collet 23 is in a non-reduced diameter state. The inner collet 61 is also in a non-reduced diameter state (expanded diameter state). The sleeve-shaped end portion 6 is positioned in the left-right direction by being pushed in so that its tip approaches the vicinity of the base portion 31 of the collet 23.

[0078] Next, an actuator (not shown) is activated to slide the drawbar 12 to the right. This causes the movable shaft 41, which was previously in the advanced position, to slide to the right toward the retracted position (see FIG. 1A), and in conjunction with this, the gripping portion 32 contracts in diameter as described above. The gripping portion 32, now in its contracted state, compresses the outer peripheral surface 6B of the inner collet 61 housed therein. The force of the gripping portion 32 compressing the outer peripheral surface 6B causes the inner collet 61 to bend inward in the radial direction R, thereby reducing the width of the split groove. This causes the inner collet 61 to contract in diameter. With the movable shaft 41 moved to the retracted position (see FIG. 1A), the inner periphery of the inner collet 61, which has been sufficiently contracted in diameter as the collet 23 has contracted in diameter, grips the outer peripheral surface 6B of the sleeve portion 6A of the sleeve-shaped end portion 6. A large contact area can be secured between the inner periphery of the inner collet 61 and the outer periphery 6B of the sleeve portion 6A, thereby enabling the sleeve-shaped end portion 6 to be firmly gripped.

[0079] When the movable shaft 41 has moved to the retracted position (see FIG. 1A), each chuck jaw 24 is in the closed position S1. At this time, the second abutment surface 55 of the jaw body 51 of the jaw portion 24A abuts against the bottom wall of the recessed groove 22J of the body flange portion 22B. When each chuck jaw 24 is in the closed position S1, the tip of the positioning protrusion 53 of the jaw portion 24A abuts against the abutment pin 39 of the pressing member 38 disposed on the left surface of the plate-shaped portion 21B.

[0080] In the dynamic balancing machine 1 with the sleeve-shaped end 6 clamped, the rotating part 3 is driven and rotated at a predetermined speed (for example, 4000 rpm) by the driving part (not shown) described above, and the vibration of the test piece 2 in this state is detected by the detecting part (not shown) described above. The detected vibration gives the unbalance of the test piece 2. Since the outer circumferential surface 6B of the sleeve part 6A, which is the rotation reference of the sleeve-shaped end 6, is gripped by the inner periphery of the inner collet 61, the rotation reference of the sleeve-shaped end 6 can be maintained with high precision.

[0081] However, when the sleeve-shaped end 6 is clamped, the claws 24A do not come into contact with the sleeve-shaped end 6. If the claws 24A were to become free, the balance (positional balance and posture balance) between the multiple chuck claws 24 may change from the adjusted state. As a result, there is a risk that the accuracy of measuring the imbalance may deteriorate.

[0082] However, in this embodiment, when the chuck jaws 24 are in the closed position S1, the jaws 24A abut against both the bottom wall of the recessed groove 22J of the main body flange portion 22B and the opposite main surface 36 of the plate-shaped portion 21B. Since the jaws 24A abut against the fixing portion (the case 21 and the sleeve main body 22) at two points, the jaws 24A do not become free even if they do not abut against the sleeve-shaped end portion 6. This makes it possible to maintain good unbalance measurement accuracy in the dynamic balancing machine 1 when the sleeve-shaped end portion 6 is supported by the test subject fixing device 4.

[0083] After measuring the unbalance of the test piece 2, the dynamic balancing machine 1 operates the actuator described above to slide the draw bar 12 to the left to its original standby position (see FIG. 6). The moving shaft 41, which had been in the retracted position until then, slides to the left together with the draw bar 12 toward the advanced position (see FIG. 6). The gripping portion 32 then returns to its non-reduced state (expanded state), and accordingly, the inner collet 61 also returns to its non-reduced state (expanded state). This releases the clamped state of the sleeve-shaped end portion 6.

[0084] As described above, this embodiment provides a test specimen fixing device 4 for a dynamic balancing machine 1 that can securely fix each of the flange-shaped end 5 and the sleeve-shaped end 6 to the rotating part 3. By using a common structure to support the flange-shaped end 5 and the sleeve-shaped end 6, changeover can be achieved by the simple process of attaching and detaching the inner collet 61. This allows for smooth changeover. Specifically, it reduces the workload of the worker performing the changeover and avoids time loss due to the changeover.

[0085] As described above, when the chuck jaws 24 are in the closed position S1, the positioning protrusions 53 of the jaws 24A abut against both of the opposite main surface 36. However, when the flange-like end portion 5 is supported by the test specimen fixing device 4, due to variations in the thickness dimension of the flange portion 5B of the flange-like end portion 5, it may not be possible for the jaws 24A to grip the flange surface 5E and for the jaws 24A to abut against the opposite main surface 36 simultaneously. Specifically, before the jaws 24A grip the flange surface 5E, the opposite main surface 36 may abut against the jaws 24A. Conversely, the jaws 24A may grip the flange surface 5E before the opposite main surface 36 abuts against the jaws 24A.

[0086] In these cases, if the abutment pin 39 were immobilized, only one of the gripping of the flange surface 5E by the claws 24A and the abutment of the opposite main surface 36 with the claws 24A would be achieved, but the other would not be achieved, which could result in a deterioration in the accuracy of imbalance measurement.

[0087] However, in this embodiment, the abutment pin 39 that abuts against the claw portion 24A can move left and right, and the abutment pin 39 is elastically pressed toward the left by the elastic pressing portion 40. Therefore, even if the claw portion 24A cannot simultaneously grip the flange surface 5E and the opposite main surface 36 cannot abut against the claw portion 24A, the abutment pin 39 that abuts against the claw portion 24A can move to achieve both gripping. This allows the flange-shaped end portion 5 to be securely fixed to the rotating portion 3 regardless of variations in the thickness of the flange portion 5B of the flange-shaped end portion 5.

[0088] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims.

[0089] Furthermore, although the case 21 and the sleeve main body 22 are provided as separate members, the case 21 and the sleeve main body 22 may be included in a single member.

[0090] Furthermore, although the example has been given in which the number of chuck jaws 24 is two, the number of chuck jaws 24 may be three or more.

[0091] Furthermore, by arranging the spindle 11 and the drawbar 12 horizontally, the central axis J of the rotating part 3 extends horizontally, but the spindle 11 and the drawbar 12 may also be arranged vertically so that the central axis J extends vertically. [Explanation of symbols]

[0092] 1: dynamic balancing machine, 2: test piece, 3: rotating part, 4: test piece fixing device, 5: flange-shaped end, 5B: flange part, 5D: spigot part, 5E: flange surface, 6: sleeve-shaped end, 6A: sleeve part, 21: case (fixed part), 21B: plate-shaped part, 21D: opening, 21E: insertion hole, 22: sleeve main body (fixed part), 22A: guide sleeve part, 22B: main body flange part, 23: collet, 23A: first dividing groove, 23B: second dividing groove, 24: chuck jaw, 24A: jaw part, 32A: opening end, 32B: intermediate part, 36: opposite main surface, J: central axis, S: circumferential direction, S1: closed position, S2: open position

Claims

1. A test specimen fixing device for fixing a test specimen to a dynamic balancing machine, comprising: a fixed portion fixed to the rotating portion, the fixed portion having a plate-like portion disposed opposite the rotating portion of the dynamic balancing machine at an interval in a direction along the central axis of the rotating portion, the plate-like portion having an insertion hole, and a guide sleeve portion inserted through the insertion hole and extending toward the rotating portion from the opposite side of the plate-like portion from the rotating portion in the direction along the central axis; a plurality of chuck jaws each having a claw portion and spanning the plate-shaped portion in the direction along the central axis, the plurality of chuck jaws being capable of changing their position between a closed position in which the plurality of claw portions approach each other and an open position in which the plurality of claw portions are farther apart from each other than in the closed position; a collet accommodated inside the guide sleeve portion, the collet being reduced in diameter in conjunction with a change in position of the chuck jaws from the open position to the closed position, When a flange-shaped end portion of the test object, which has a spigot portion and a flange portion, is fixed to the rotating portion, the inner periphery of the open end portion of the collet, which is in a state of being reduced in diameter as the chuck jaws are changed to the closed position, grips the spigot portion, and the jaw portions of the chuck jaws, which are in the closed position, grip the flange surface of the flange portion on the side opposite to the rotating portion with respect to the plate-shaped portion, a test piece fixing device for a dynamic balancing machine, in which, when a sleeve-shaped end portion of a test piece, having a sleeve portion, is fixed to the rotating portion, the outer periphery of the sleeve portion is supported by the inner periphery of the collet, which is in a contracted state as the chuck jaws change their position to the closed position;

2. a plurality of first dividing grooves are formed in the open end of the collet, and are aligned in a circumferential direction of the collet; a plurality of second dividing grooves are formed in a circumferential direction of the collet in a middle portion of the collet excluding the opening end portion, 2. The test piece fixing device for a dynamic balancing machine according to claim 1, wherein the number of said first dividing grooves is greater than the number of said second dividing grooves.

3. the fixed portion further includes a main body flange portion that is disposed on the opposite side of the plate-shaped portion from the rotating portion and that is connected to the guide sleeve portion, 3. The test subject fixing device for a dynamic balancing machine according to claim 1, wherein, when the chuck jaws are in the closed position, the claw portions abut against both an outer periphery of the body flange portion and an opposite main surface of the plate-shaped portion opposite to the rotating portion.

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