Spindle device, machine tool equipped with spindle device, and balancing machine

Abstract

A spindle device and a machine tool equipped with the spindle device are provided. The spindle device can clamp two positions inside and outside a multi-functional holding member through a single drive unit. In the spindle device, the holding member is used by being mounted on the front end of the spindle. The holding member has a first clamped portion and a second clamped portion arranged in a double layer. The first pull rod (8) and the second pull rod (9) are overlapped and arranged in series within the spindle barrel. When the first pull rod (8) is pushed forward by the spacer block (17), the first pull rod (8) resists the acting force of the first disc spring assembly (10) and advances, and the first clamping mechanism is released. Subsequently, the second pull rod (7) resists the acting force of the second disc spring assembly (11) and advances, and the second clamping mechanism is also released. As the spacer block (17) retracts, through the acting forces of the first disc spring assembly (10) and the second disc spring assembly (11), the first clamping mechanism of the first pull rod (8) and the second clamping mechanism of the second pull rod (9) are actuated.

Description

Technical Field

[0001] The present invention relates to a spindle device, a machine tool equipped with the spindle device, a balancing machine, etc. The above spindle device is used by mounting a holder for a tool or a workpiece on the front end of the spindle. The holder for the tool or the workpiece has a first clamped portion and a second clamped portion arranged in a double layer on the inner and outer sides on its base side. Background Art

[0002] The inventor of the present invention has developed a multifunctional holder that can mount both a tool and a workpiece on the spindle of a machine tool. At the same time as developing the holder, a holder holding mechanism for mounting the above-mentioned holder on the spindle and a spindle device having such a holder holding mechanism have also been developed. As the prior art disclosing the above technology, as shown in Patent Document 1. In the spindle device of Patent Document 1, a separate clamping structure for mounting the above-mentioned multifunctional holder is provided. Specifically, for example, as shown in FIG. 2 thereof, a structure having the following components is adopted: an outer gripping mechanism (composed of an outer pull rod 85, outer balls 92a, etc.) for clamping (holding) the holder itself and an inner gripping mechanism (composed of an inner pull rod 84, inner balls 92b, etc.) for clamping the head of the movable traction stud of the chuck mechanism for opening and closing the holder. That is, it is a mechanism for clamping a multifunctional holder having double clamped portions on the inner and outer sides. Then, the outer pull rod 85 and the inner pull rod 84 are respectively advanced and retracted by two cylinder devices (double-layer push-pull mechanism 9a) arranged on the upper part of the spindle to perform a clamping action.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-284768 Summary of the Invention

[0006] Technical Problem to be Solved by the Invention

[0007] However, in order to clamp the two clamped portions as described above, two cylinder devices are respectively arranged in the spindle device. Such a structure causes the spindle device to be enlarged and weighted, and also causes high cost due to the need for a plurality of cylinder devices. In addition, since the operations of the two cylinder devices must be controlled, the operation becomes troublesome. In addition, maintenance also becomes inconvenient.

[0008] Therefore, a mechanism that can clamp two places on the inner and outer sides of the above-mentioned holder using only one driving unit such as a cylinder device is required.

[0009] An object of the present invention is to solve the above-described technical problems, and to provide a spindle device, a machine tool equipped with the spindle device, and a balancing machine that can clamp two locations inside and outside a multifunctional holding member by driving one pushing unit.

[0010] Technical solutions for solving technical problems

[0011] In a first aspect for solving the above technical problems, a spindle device that mounts a holding member for a tool or a workpiece on the front end of a spindle for use, wherein the holding member has a first clamped portion and a second clamped portion that are arranged in a double layer on the inner side and the outer side on the base side thereof. The spindle device is characterized by including a first drawbar and a second drawbar. The first drawbar has a first clamping mechanism at the front end side for clamping the first clamped portion of the holding member, and the second drawbar has a second clamping mechanism at the front end side for clamping the second clamped portion of the holding member. The first drawbar and the second drawbar are arranged in series and can move forward and backward in the spindle barrel. The first drawbar is configured to be pressed by a pushing unit in the forward direction, thereby advancing against the acting force generated by a first biasing unit. The second drawbar is configured to be directly or indirectly pushed by the first drawbar as the first drawbar advances, and to advance against the acting force generated by a second biasing unit. The first drawbar advanced by the pushing unit releases the first clamping mechanism at a specified forward and backward position, and the second clamping mechanism of the second drawbar pushed by the first drawbar is also released.

[0012] With the release of the pressing force generated by the pushing unit, the first drawbar and the second drawbar at the specified forward and backward position respectively retreat toward the base direction of the spindle barrel by the acting forces of the first biasing unit and the second biasing unit, and the first clamping mechanism of the first drawbar and the second clamping mechanism of the second drawbar operate. In this way, the first clamping mechanism and the second clamping mechanism can be released only by pushing the pushing unit. In addition, by retracting the pushing unit, the first biasing unit and the second biasing unit can be operated only by the acting forces of the first biasing unit and the second biasing unit, the two clamped portions of the holding member can be clamped, and the structure for loosening is simplified, which is beneficial to the miniaturization and low cost of the spindle device.

[0013] The "first drawbar" has a first clamping mechanism at the front end side for clamping the first clamped portion of the holding member. The front end side refers to the front end side of the spindle. The arrangement position of the first clamped portion of the holding member is determined according to the relationship with the second clamped portion, and can be on the inner side or the outer side.

[0014] The "second pull rod" is provided with a second clamping mechanism at the front end side for clamping the second clamped portion of the holding member. The second pull rod is in a relationship of directly or indirectly pushing the first pull rod as the first pull rod advances. The first pull rod and the second pull rod are arranged in series and may partially overlap.

[0015] The "pushing unit" may include, for example, a hydraulic cylinder device, a cylinder device, or a pressing member such as a cylinder (piston) with a motor device or the like as a driving source. The pushing unit (pressing member) may or may not be connected to the first pull rod. In the case of not being connected, it only contacts for pushing, so it will not become a load during the rotation of the spindle barrel.

[0016] When the "first biasing unit" is pushed by the pushing unit to advance the first pull rod, it is compressed as it advances, and an acting force exists inside. By releasing the pressing force from the pushing unit, the first pull rod is retracted toward the base of the spindle barrel by the acting force. The first biasing unit preferably has a certain degree of acting force inside from the beginning, and is preferably configured to always push the first pull rod toward the base of the spindle barrel using this acting force.

[0017] In the "second biasing unit", when the first pull rod is pushed by the pushing unit to advance and the second pull rod also advances accordingly, the second pull rod is compressed, and an acting force exists inside. By releasing the pressing force from the pushing unit, the second pull rod is retracted toward the base of the spindle barrel by the acting force. The second biasing unit preferably has a certain degree of acting force inside from the beginning, and is preferably configured to always push the second pull rod toward the base of the spindle barrel using this acting force.

[0018] When the first biasing unit and the second biasing unit are, for example, spring devices, they may be, for example, coil springs, disc springs, leaf springs, etc. A cylinder device or a hydraulic cylinder device may also be used.

[0019] The "clamped portion" needs to be a shape that can be clamped (gripped) by the clamping mechanism. The clamped portion preferably has, for example, a protruding portion or a shape into which a member on the clamping side can be inserted. This is because the clamped portion interferes with the clamping mechanism and prevents the holding member from moving in the removal direction.

[0020] The "clamping mechanism" preferably has a structure of an interfering body that advances and retracts in the radial direction of the spindle, for example, with respect to the clamped portion. Moreover, it preferably appears and disappears in the passage through which the clamped portion is inserted to clamp the clamped portion. The shape of the interfering body is preferably, for example, spherical, cylindrical, or barrel-shaped. Alternatively, the interfering body may be arranged to sway around the axis, for example, like a collet, and advance and retract in the radial direction of the spindle.

[0021] Since "the second pull rod is indirectly or directly pushed by the first pull rod", the first pull rod can contact and push the second pull rod, or it can be pushed via other components.

[0022] The "holding member" has a first clamped portion and a second clamped portion arranged in a double layer on the inner side and the outer side on its base side. It is preferably a multi-functional holding member with high versatility that can be used both for tools and workpieces. Even if it has a first clamped portion and a second clamped portion, it can be, for example, a holding member specific to tools. If there are two clamping portions of the first clamped portion and the second clamped portion, the tensile force of the holding member is increased, so it is particularly suitable for high-load cutting. In the above case, it functions not as a multi-functional holding member but as a tool holding member.

[0023] In the case of a multi-functional holding member, as a tool, for example, various machining tools such as milling cutters, drills, end mills, drills, reamers, etc. equipped on the ATC (Automatic Tool Change) of a machining center can be clamped by a chuck mechanism and installed on the front end side for use. In the case of a workpiece, the workpiece is directly or indirectly clamped and installed on the front end side by a chuck mechanism, and for example, the workpiece can be machined by a numerically controlled machine tool. The chuck mechanism also includes a clamping mechanism. For example, the first clamped portion is formed on a rod member such as a drawbolt, and the first clamped portion is pushed and pulled to open and close the chuck mechanism. Preferably, the second clamped portion is formed on the mounting portion installed in the holding member mounting hole, and the holding member is mounted on the front end of the spindle barrel through the second clamped portion.

[0024] In addition, as a second mode, when the above-mentioned pushing unit does not press the first pull rod, it retracts to a position where it does not contact the first pull rod.

[0025] Thus, when the first clamping mechanism and the second clamping mechanism of the second pull rod act and the holding member is clamped, since the pushing unit does not become a load on the spindle barrel side, the energy consumption and rotational unevenness during spindle rotation can be reduced.

[0026] In addition, as a third mode, the acting force obtained when the above-mentioned second biasing unit applies force is greater than the acting force obtained when the above-mentioned first biasing unit applies force.

[0027] Thus, in the state where the first clamping mechanism and the second pull rod are released by the pushing of the pushing unit and the pushing pressure generated by the pushing unit is released, first, the second clamping mechanism of the second pull rod is actuated by the acting force of the second biasing unit, and then, with a time difference, the first clamping mechanism of the first pull rod is actuated.

[0028] In addition, as a fourth method, when the first pull rod retreats from the specified advanced / retreated position, after the second clamping mechanism of the second pull rod operates, the first clamping mechanism of the first pull rod operates.

[0029] By setting the first clamping mechanism to operate with a time difference after the second clamping mechanism operates in this way, it is possible to prevent the misinstallation of the holding member.

[0030] In the third and fourth methods, since it is possible to perform, for example, a two-stage clamping operation in which the holding member is correctly installed on the spindle device and clamped by the second clamping mechanism, and then the first clamping mechanism clamps the head of the movable traction stud, it is not easy to have problems such as clamping the traction stud in an inclined state or the first clamping mechanism not operating smoothly before the holding member is correctly installed on the spindle device.

[0031] In addition, as a fifth method, the first pull rod has an outer peripheral surface that contacts the inner peripheral surface of the second pull rod, and slides back and forth guided by the inner peripheral surface and the outer peripheral surface.

[0032] Thereby, during the relative forward and backward movement processes in both cases such as when the first pull rod moves forward and backward or when the first pull rod is pushed by the first pull rod to move forward and backward, it is possible to make the central axes coincide and move without vibration.

[0033] In addition, as a sixth method, the first clamping mechanism and the second clamping mechanism are arranged at positions offset in the front-rear direction. The second clamping mechanism is arranged closer to the front end of the spindle than the first clamping mechanism.

[0034] Thereby, it is possible to easily cope with, for example, the case where the positions of the first clamped portion and the second clamped portion of the holding member are offset in the front-rear direction. Since the first clamping mechanism and the second clamping mechanism are not in the same position, interference between the two will not occur.

[0035] In addition, as a seventh method, the first clamping mechanism has an interference body that moves forward and backward in the radial direction of the spindle. In a state where the first pull rod is arranged at the first advanced / retreated position, the interference body that clamps the first clamped portion is in a position facing a storage portion formed on the inner peripheral surface of the second pull rod, whereby the first clamping mechanism is released.

[0036] This is the configuration of the release structure for specifically releasing the first clamping mechanism from the clamped state. Thereby, it is possible to release the clamped state (loosen) in which the first clamping mechanism clamps the first clamped portion of the holding member.

[0037] Further, as an eighth mode, the second clamping mechanism has an interfering body that moves forward and backward in the radial direction of the main shaft. In a state where the first pull rod is disposed at the first advancing and retreating position, the interfering body that clamps the second clamped portion is in a position where it is in surface contact with a storage portion formed on the inner peripheral surface of the main shaft cylinder, whereby the second clamping mechanism is released.

[0038] This is a configuration of a specific structure for releasing the clamping state of the second clamping mechanism. In this way, the clamping state (loosening) of the second clamped portion of the holding member by the second clamping mechanism can be released.

[0039] Here, the interfering body moves forward in the radial direction to clamp the clamped portion, and by maintaining this clamping state, the holding member is installed. It preferably has an engaging portion that prevents the holding member from moving in the taking-out direction. As the interfering body that moves forward and backward in the radial direction, for example, balls or chucks or split claws as described above can be disposed.

[0040] Further, as a ninth mode, the holding member is installed in a holding member mounting hole formed at the front end of the main shaft cylinder.

[0041] That is, it is in a state where the holding member is installed in the holding member mounting hole of the main shaft device, and the first clamped portion and the second clamped portion of itself are clamped by the first clamping mechanism and the second clamping mechanism.

[0042] Further, as a tenth mode, the holding member for the workpiece is configured such that: the holding member for the workpiece is configured such that the first clamped portion is formed on a rod member that can move forward and backward. In a state where the second clamping mechanism applies an action to the holding member installed at the front end of the main shaft, the rod member is pulled out via the first clamped portion, whereby the workpiece in the loosened state is clamped, and by the first pull rod moving forward, the rod member is pushed back to loosen the workpiece in the clamped state.

[0043] Thereby, since the rod member can be moved forward and backward by the first pull rod in a state where the second clamping mechanism is actuated to clamp the holding member for the workpiece, the workpiece can be clamped and loosened only by the first clamping mechanism of the first pull rod. The rod member refers to, for example, a traction stud, a traction bolt, etc.

[0044] Further, as an eleventh mode, the first biasing unit and the second biasing unit are compression spring devices, and bias the first pull rod and the second pull rod in the backward direction.

[0045] By using a compression spring device in this way, it can contribute to the weight reduction and compactification of the biasing unit for biasing the first pull rod and the second pull rod in the backward direction.

[0046] In addition, as a twelfth aspect, it is a machine tool equipped with the spindle device described in any one of the first to eleventh aspects.

[0047] In addition, as a thirteenth aspect, it is a balancing machine equipped with the spindle device described in any one of the first to eleventh aspects.

[0048] As the machine tool, it can be, for example, a numerically controlled machine tool, a machining center, or even a numerically controlled machine tool with an ATC. In a machining center, it is preferably used as the spindle device of an ATC (Automatic Tool Changer).

[0049] The inventions of the above first to thirteenth aspects can be arbitrarily combined. In particular, it is preferable to combine the structure of the first aspect with at least one structure of the inventions of the first to thirteenth aspects. Any constituent elements of the inventions of the first to thirteenth aspects can also be combined with other constituent elements.

[0050] Advantages of the Invention

[0051] In the above invention, the first clamping mechanism and the second clamping mechanism can be released only by pushing with the pushing unit. In addition, by retracting the pushing unit, the first clamping mechanism and the second clamping mechanism can be actuated only by the action of the acting forces of the first biasing unit and the second biasing unit, and the structure for clamping and releasing the two clamped portions of the holding member is simplified, which is beneficial to the miniaturization and cost reduction of the spindle device. Description of the Drawings

[0052] Figure 1 It is a partial broken-away longitudinal sectional view of the spindle unit of Embodiment 1.

[0053] Figure 2A It is a longitudinal sectional view of the main part of the device for explaining the state in which the first pull rod and the second pull rod are retracted the most without pressing the first pull rod with a spacer block in the spindle device of the spindle unit of Embodiment 1.

[0054] Figure 2B It is a longitudinal sectional view of the main part of the device for explaining the state in which the first pull rod has moved downward only by pressing the first pull rod with a spacer block in the spindle device of the spindle unit of Embodiment 1.

[0055] Figure 2C It is a longitudinal sectional view of the main part of the device for explaining the state in which the first pull rod and the second pull rod have moved downward the most without pressing the first pull rod with a spacer block in the spindle device of the spindle unit of Embodiment 1.

[0056] Figure 2D It is for explaining the holding member relative to Figure 2CA longitudinal sectional view of the main part of a device for explaining the state of the spindle device of the spindle unit during the installation and removal process.

[0057] Figure 2E A longitudinal sectional view of the main part of a device for explaining the state in which the spacer block in the pressed state in the spindle device of the spindle unit in the first embodiment is slightly lifted, only the second pull rod moves upward, and the flange portion of the holding member is clamped (the state in which the second clamping mechanism has been actuated).

[0058] Figure 2F A longitudinal sectional view of the main part of a device for explaining the state in which the spacer block in the pressed state in the spindle device of the spindle unit in the first embodiment is completely disengaged, and the first and second pull rods move in both directions and are respectively clamped by the raised portion and the flange portion of the holding member (the state in which both the first and second clamping mechanisms have been actuated).

[0059] Figure 3A A longitudinal sectional view of the main part of a device for explaining the state in which the spacer block in the pressed state in the spindle device of the spindle unit in the first embodiment is completely disengaged, and the first and second pull rods move in both directions and the raised portion and the flange portion of the holding member are respectively clamped (the state in which both the first and second clamping mechanisms have been actuated).

[0060] Figure 3B An enlarged explanatory view for explaining the state in which, around the clamping mechanism of the spindle device of the spindle unit in the first embodiment, with the raised portion and the flange portion of the holding member respectively clamped, the first pull rod retracts significantly and pulls out the traction stud from the holding member.

[0061] Figure 4A An enlarged explanatory view for explaining the state in which, around the clamping mechanism of the spindle device of the spindle unit in the first embodiment, the first and second pull rods advance to a position where the inner and outer balls are locked and cannot protrude or retract.

[0062] Figure 4B An enlarged explanatory view for explaining the state in which, around the clamping mechanism of the spindle device of the spindle unit in the first embodiment, the first and second pull rods advance to a position where the inner and outer balls can freely protrude and retract.

[0063] Figure 4C An enlarged explanatory view for explaining the state around the clamping mechanism of the spindle device of the spindle unit in the first embodiment, in Figure 4B the state where neither the raised portion nor the flange portion of the holding member being installed or removed midway is clamped.

[0064] Figure 4D An enlarged explanatory view for explaining the state around the clamping mechanism of the spindle device of the spindle unit in the first embodiment, where the second pull rod is fromFigure 4C An enlarged explanatory view for explaining the state where the flange portion of the holding member is clamped while the state of the [object] retreats.

[0065] Figure 4E This is an enlarged explanatory view for explaining the state where the first drawbar retreats from the state where both the raised portion and the flange portion of the holding member are clamped around the clamping mechanism of the spindle device of the spindle unit in the first embodiment. Figure 4D An enlarged explanatory view for explaining the state where the first drawbar retreats from the state where both the raised portion and the flange portion of the holding member are clamped.

[0066] Figure 5 This is a partially enlarged perspective view of the front end of the first drawbar.

[0067] Figure 6 (a) of [figure number] is a front view of the chuck holding member in the chuck open state. Figure 6 (b) of [figure number] is a bottom view of the chuck holding member in the chuck open state.

[0068] Figure 7 (a) of [figure number] is a front view of the chuck holding member in the chuck closed state. Figure 7 (b) of [figure number] is a bottom view of the chuck holding member in the chuck closed state.

[0069] Figure 8 This is a partially cut-away longitudinal sectional view of the spindle unit in the second embodiment.

[0070] Figure 9 (a) of [figure number] is a front view of the tool chuck holding member. Figure 9 (b) of [figure number] is a longitudinal sectional view of the tool chuck holding member.

[0071] Figure 10 This is an explanatory view schematically explaining the outline of the balancing machine in the third embodiment. Detailed Embodiment

[0072] Hereinafter, the embodiments will be described with reference to the drawings.

[0073] <First Embodiment>

[0074] As Figure 1 shown, the main components of the spindle unit 1 of the automatic tool changer include a spindle device 2, a bearing unit 4 surrounded by a housing 3 disposed around the spindle device 2, a spindle rotation mechanism 5, and a cylinder device 6. First, the outline of the spindle unit 1 will be described. In the following description, it is assumed that the spindle device 2 in the spindle unit 1 is arranged in the vertical direction, and the front end side of the spindle device 2 is the lower side. The spindle unit 1 is supported by a spindle frame (not shown).

[0075] As Figure 1 and Figures 2A - 2FAs shown, the spindle device 2 made of an alloy includes a substantially cylindrical spindle barrel 7. The spindle barrel 7 has a passage communicating in the vertical direction and a circular outer peripheral shape. A first pull rod 8 and a second pull rod 9 are accommodated in the spindle barrel 7. Between the first pull rod 8 and the spindle barrel 7, a first disc spring assembly 10 serving as a first biasing unit is arranged. Between the second pull rod 9 and the spindle barrel 7, a second disc spring assembly 11 serving as a second biasing unit is arranged.

[0076] The spindle device 2 is surrounded by a bearing unit 4. The bearing unit 4 is a part that rotatably supports the spindle device 2 in the spindle unit 1. The inner cylinder portion 4A of the bearing unit 4 is fixed to the spindle device 2 and is formed as a part that rotates together with the spindle device 2. The outer cylinder portion 4B of the bearing unit 4 is fixed to the housing 3 side and is formed as a non-rotating part. The housing 3 is supported by a spindle frame (not shown).

[0077] On the outer periphery of the first cylinder portion 7A at the upper part of the spindle barrel 7, a first pulley 12 constituting the spindle rotation mechanism 5 is fixedly installed. At a side position separated from the first pulley 12, a second pulley 13 is supported by a bearing (not shown) fixed to the spindle frame side. A drive belt 14 for transmission is wound around the outer peripheries of the first pulley 12 and the second pulley 13. The output shaft 15a of the motor device 15 is coaxially connected to the second pulley 13. The motor device 15 is supported on the spindle frame side (not shown).

[0078] A cylinder device 6 is arranged at the upper part of the spindle barrel 7. The cylinder device 6 is supported on the spindle frame side (not shown). The cylinder device 6 allows a piston rod 6a driven by an air compressor (not shown) to advance and retract. The piston rod 6a is arranged to protrude and retract downward, and a cylindrical cushion block 17 is connected to the front end of the piston rod 6a.

[0079] Next, the spindle device 2 will be described in more detail.

[0080] As shown in Figure 1 、 Figures 2A - 2F , a spindle cover 18 is connected to the front end side of the spindle barrel 7. The spindle cover 18 is a cylindrical body that is vertically connected and has a circular cross-section. The spindle cover 18 is fixed in a state of being inserted into the front end of the spindle barrel 7. The spindle barrel 7 has three regions with different inner diameter sizes, and from above in sequence are a first cylinder portion 7A, a second cylinder portion 7B, and a third cylinder portion 7C. The spindle barrel 7 is configured such that the inner diameter increases in the above-mentioned order. A frustum-shaped retainer mounting hole 19 with a diameter increasing downward is formed on the inner peripheral surface of the spindle cover 18. The spindle cover 18 and the spindle barrel 7 together constitute a frame body 20 of the spindle device 2.

[0081] In the internal space of the frame body 20, the first pull rod 8 and the second pull rod 9 are arranged in series in a partially overlapping manner.

[0082] A fixing ring 21 is fixedly installed inside the second cylinder part 7B of the main shaft cylinder 7. A passage 23 communicating in the vertical direction is formed at the center of the fixing ring 21.

[0083] The first pull rod 8 is configured such that the outer shape of its cross-section is circular and it is composed of three parts with different diameters. That is to say, the first pull rod 8 has a first large-diameter part 8A, a small-diameter part 8B, and a second large-diameter part 8C. The small-diameter part 8B extends downward (forward) adjacent to the first large-diameter part 8A and has a smaller diameter. The second large-diameter part 8C is connected to the front end side of the small-diameter part 8B and has the largest diameter. The front end of the second large-diameter part 8C is formed into a cylindrical part 8D, and the cylindrical part 8D is formed into a cylindrical shape with the same outer shape as the second large-diameter part 8C. The internal space of the cylindrical part 8D is in a position that houses the rear end side of the traction stud 55 of the chuck holder 51 to be described later and clamps the raised part 56. A coolant passage 24 communicating in the vertical direction is formed at the axial center position of the first pull rod 8.

[0084] Around the first large-diameter part 8A of the first pull rod 8, a first disc spring assembly 10 is arranged. The first disc spring assembly 10 is arranged between the first large-diameter part 8A and the main shaft cylinder 7 and is clamped in a state of applying force between the nut 25 fixedly installed at the upper end of the first large-diameter part 8A and the fixing ring 21 in the vertical direction.

[0085] The second pull rod 9 is also configured such that the outer shape of its cross-section is circular. The second pull rod 9 has a cylindrical main body 9A, a flange part 9B formed to protrude outward from the periphery at a position near the upper part of the main body 9A, a partition wall 9C located between the main body 9A and the flange part 9B, and an annular part 9D protruding upward in a ring shape. A passage 26 is formed in the partition wall 9C.

[0086] The part of the second pull rod 9 near the lower part of the main body 9A is housed inside the main shaft cover 18 and is in close contact with the inner peripheral surface 18a, and the outer periphery of the flange part 9B is in close contact with the second cylinder part 7B of the main shaft cylinder 7. Through the above-mentioned close contact structure, it is possible to guide the second pull rod 9 when it linearly slides and moves in the vertical direction. The internal space near the front end of the main body 9A is in a position that houses the flange part 57 of the chuck holder 51 to be described later and clamps the reduced-diameter part 58.

[0087] Around the main body 9A of the second pull rod 9, a second disc spring assembly 11 is arranged. The second disc spring assembly 11 is arranged between the main body 9A and the main shaft cylinder 7 and is clamped in a state of applying force between the flange part 9B and the main shaft cover 18 in the vertical direction. A pin 27 for preventing the circumferential rotation of the second pull rod 9 is arranged between the second pull rod 9 and the fixing ring 21. A key 28 is installed at the front end of the holder mounting hole 19, and this key 28 is used to engage with the chuck holder 51 side to prevent the chuck holder 51 from rotating circumferentially when the chuck holder 51 is installed on the main shaft device 2.

[0088] The arrangement states of the first pull rod 8 and the second pull rod 9 with respect to the frame 20 configured as described above will be described.

[0089] The second pull rod 9 is configured to be slidably movable within the cylindrical frame 20, and is also configured as a cylinder to accommodate the first pull rod 8 and allow the sliding movement of the first pull rod 8. The first pull rod 8 is slidably accommodated within the second pull rod 9 near the lower part. That is to say, the frame 20, the first pull rod 8, and the second pull rod 9 are configured to form a double-layer sliding mechanism that overlaps inside and outside.

[0090] In the first pull rod 8, the portion near the lower end of the first large-diameter portion 8A is accommodated in the ring portion 9D on the side of the second pull rod 9, the small-diameter portion 8B communicates with the passage 26 of the partition wall 9C on the side of the second pull rod 9, and the second large-diameter portion 8C is disposed within the main body 9A on the side of the second pull rod 9. The components are arranged in a closely attached state, and can guide the first pull rod 8 when it slides linearly in the vertical direction.

[0091] In the first pull rod 8, the lower end of the first large-diameter portion 8A abuts against the upper surface of the partition wall 9C on the side of the second pull rod 9, thereby restricting the further downward movement of the first pull rod 8. The above position is set as the lowermost position, and on the upper side, the upper end of the second large-diameter portion 8C abuts against the lower surface of the partition wall 9C, thereby restricting the further upward movement. In the second pull rod 9, the upper surface of the flange portion 9B abuts against the lower surface 28 of the second cylinder portion 7B of the main shaft cylinder 7, thereby restricting the further upward movement of the second pull rod 9. In addition, in the second pull rod 9, the front end of the main body 9A abuts against the shelf portion 29 protruding inward in the circumferential direction of the inner periphery of the main shaft cover 18, thereby restricting the further downward movement of the second pull rod 9. The front end of the cylindrical portion 8D of the first pull rod 8 is always disposed at a position retracted from the front end of the second pull rod 9.

[0092] Next, according to Figures 2A - 2F , Figures 4A - 4E and Figure 5 , the clamping mechanism of the first pull rod 8 and the second pull rod 9 will be described.

[0093] The first pull rod 8 clamps the side of the traction stud 55 of the chuck holder 51 described later, and the second pull rod 9 clamps the side of the mounting portion 53 of the chuck holder 51 described later.

[0094] As Figure 5As shown, a plurality of first through holes 31 are formed in the cylindrical portion 8D of the first pull rod 8 at a predetermined interval in the circumferential direction. Each first through hole 31 has a circular opening portion that communicates the inside and outside in the radial direction of the cylindrical portion 8D of the first pull rod 8. Each first through hole 31 is configured such that the diameter of the inner opening portion is smaller than the diameter of the outer opening portion, and the inner wall is formed in a conical shape. A first ball 32 is accommodated in each first through hole 31. The diameter of the first ball 32 is configured to be larger than the diameter of the inner opening portion of the first through hole 31 and smaller than the diameter of the outer opening portion.

[0095] Second through holes 33 are formed at a position near the front end of the second pull rod 9 at a predetermined interval in the circumferential direction. The structure of the second through holes 33 is the same as that of the first through holes 31 and will be omitted. In addition, second balls 34 are accommodated in the respective second through holes 33. The structure and operation of the second balls 34 are the same as those of the first balls 32, and the detailed description thereof will be omitted.

[0096] On the inner side of the main body 9A of the second pull rod 9, at a position above the second through holes 33, first recesses 35 are formed at a predetermined interval in the circumferential direction.

[0097] The first recess 35 is formed in a circular opening shape and has a diameter that is the same as the diameter of the outer opening portion of the first through hole 31. The first recess 35 is configured to be a recess shape that is slightly deeper than the protruding amount of the first ball 32 in the state where the first ball 32 enters the innermost side of the first through hole 31 ( Figure 4A , Figure 4E state). That is, in a state where the first recess 35 is aligned with the first through hole 31, the first ball 32 retracts outward and is in a released state. On the other hand, when not aligned, the first ball 3 is in a state where it slightly protrudes inward of the first through hole 31 on the front end side and cannot move inward or outward and is held, and is in a clamped state. In the present embodiment, clamping means that the traction stud 55 of the chuck holding member 51 and the shaft-like portion of the mounting portion 53 are pressed from the periphery by a plurality of first balls 32.

[0098] The first recess 35 is aligned with the first through hole 31 according to the relative positional relationship between the first pull rod 8 and the second pull rod 9. When the first recess 35 is aligned with the first through hole 31, the first ball 32 is in a floating fit state, so it can retract outward and is in a released state. On the other hand, when not aligned, the first ball 3 is in a state where it slightly protrudes inward of the first through hole 31 on the front end side and cannot move inward or outward and is held, and is in a clamped state. In the present embodiment, clamping means that the traction stud 55 of the chuck holding member 51 and the shaft-like portion of the mounting portion 53 are pressed from the periphery by a plurality of first balls 32.

[0099] Second recesses 37 are formed on the inner peripheral surface 7a of the lower part of the main spindle cylinder 7 and near the base side of the holder mounting hole 19 at a predetermined interval in the circumferential direction.

[0100] The second recess 37 is configured to have a diameter larger than that of the second through-hole 37 in order to avoid interference between the second drawbar 9 and the main spindle barrel 7. Further, in a state where the second recess 37 is aligned with the second through-hole 33, the second ball 34 retracts last, and in a state where it is recessed into the second recess 37, the second ball 34 does not protrude from the surface (flush plane) of the second drawbar 9, which is the same as the case of the first drawbar 8 side. The wall surface of the second recess 37 is formed in a conical shape that facilitates entry into and exit from the second through-hole 33.

[0101] The second recess 37 is disposed at a specified retraction / advance position by the second drawbar 9 so as to be aligned with the second through-hole 33. Similar to the above, in the aligned state, the second ball 34 is in a loose fit state, so it can retract outward and is in a released state. On the other hand, in a non-aligned case, in a state where the second ball 34 slightly protrudes on the front end side, it cannot move inward or outward and is held, and is in a clamped state.

[0102] A first clamping mechanism is constituted between the first drawbar 8 and the second drawbar 9 by the first through-hole 31, the first ball 32, the first recess 35, etc.

[0103] A second clamping mechanism is constituted between the main spindle barrel 7 and the second drawbar 9 by the second through-hole 33, the second ball 34, the second recess 37, etc.

[0104] The main spindle unit 1 configured as described above is mounted on a seat plate (not shown) inside a machining center, and processes a workpiece under the control of a computer device (not shown).

[0105] In the present embodiment, Figure 6 the chuck holder 51 with three jaws shown in (a) and (b) of Figure 7 is set to be mounted in the holder mounting hole 19 of the spindle device 2. The chuck holder 51 is composed of a holder main body 52 that houses a chuck mechanism (not shown) and a mounting portion 53 for mounting on the spindle device 2. The mounting portion 53 is a conical protrusion integrally formed with the holder main body 52. The outer peripheral shape of the mounting portion 53 corresponds to the inner peripheral shape of the holder mounting hole 19. Three jaw portions 54 are movably mounted on the holder main body 52. Figure 6 The state of (a) and (b) of Figure 7 is the state where the jaw portions 54 are opened to the maximum, and the state of (a) and (b) of

[0106] At the front end of the traction stud 55, there is integrally formed a raised portion 56 which is an engaging portion, protrudes outward, and has a substantially ellipsoidal shape. At the front end of the mounting portion 53, there is integrally formed a flange portion 57 which is a disc-shaped and protrudes outward and is an engaging portion. Between the mounting portion 53 adjacent to the flange portion 57 and the flange portion 57, there is formed a reduced-diameter portion 58 which is an engaging portion. The reduced-diameter portion 58 is a portion where a discontinuous depression in the shape of a collar is formed over the entire circumference with respect to the continuous tapered shape of the mounting portion 53. The flange portion 57 is disposed inside the holder mounting hole 19 when the chuck holder 51 is mounted on the holder mounting hole 19 (in the state where the tapered surfaces are in close contact with each other).

[0107] Next, according to Figures 2A - 2F , Figures 4A - 4E , the clamping operation and the releasing operation of the chuck holder 51 in the spindle unit 1 with respect to the spindle device 2 will be described. The state of the chuck holder 51 when the chuck holder 51 is mounted on the spindle device 2 is Figure 6 in the state where the claw portions 54 in (a) and (b) are opened to the maximum, that is, the default state.

[0108] A. Figure 2A and Figure 4A are the states where the first pull rod 8 is pushed to the uppermost position by the acting force of the first disc spring assembly 10, and the second pull rod 9 is pushed to the uppermost position by the acting force of the second disc spring assembly 11. Both the first clamping mechanism and the second clamping mechanism are in the released state. The above-mentioned advancing and retreating position is set as the initial advancing and retreating position of the first pull rod 8. In Figure 2A , the initial advancing and retreating position is set as S1, and the end position of the first pull rod 8 is taken as a reference. In addition, the end position of the following first pull rod 8 is judged by a proximity sensor (not shown).

[0109] A more detailed description will be given of the force application state of the first disc spring assembly 10 to the first pull rod 8 and the force application state of the first disc spring assembly 10 to the first pull rod 8. The first disc spring assembly 10 presses the nut 25 with reference to the fixing ring 21. Then, the first pull rod 8 is pushed upward by the nut 25. The upward movement of the first pull rod 8 is restricted when the upper end of the second large-diameter portion 8C abuts against the ring portion 9C. In addition, the second disc spring assembly 11 presses the flange portion 9B with reference to the spindle cover 18. Then, the second pull rod 9 is pushed upward by the flange portion 9B. The upward movement of the flange portion 9B is restricted when the flange portion 9B abuts against the lower surface 28 of the second cylindrical portion 7B.

[0110] At this time, as Figure 4AAs shown, the first ball 32 in the first through-hole 31 is locked in a clamping position that does not allow movement in the direction of the first recess 35. The second ball 34 in the second through-hole 33 is also locked in a clamping position that does not allow movement in the direction of the second recess 37. That is to say, in the above state, the chuck holder 51 is in a state where the first ball 32 and the second ball 34 interfere with each other and cannot be connected yet.

[0111] B. Next, through a specified control action, the spacer 17 at the front end of the piston rod 6a of the cylinder device 6 is moved downward, pressing the first pull rod 8 downward. By the downward movement of the spacer 17, the first pull rod 8 is moved downward against the acting force generated by the first disc spring assembly 10 that pushes the first pull rod 8 upward. The first pull rod 8 moves from Figure 2A the S1 position to Figure 2B the S2 position. At this time, since the spring force of the second disc spring assembly 11 is stronger than the spring force of the first disc spring assembly 10, when the first disc spring assembly 10 is compressed due to the downward movement of the spacer 17, the second disc spring assembly 11 will not be compressed. That is to say, only the first pull rod 8 moves downward, while the second pull rod 9 does not move downward and stays in this position.

[0112] Figure 2B It is in a released state where the first pull rod 8 moves downward and the first ball 32 in the first through-hole 31 is allowed to move in the direction of the first recess 35. On the other hand, the second ball 34 in the second through-hole 33 still remains in the clamped position where it is locked and not allowed to move in the direction of the second recess 37.

[0113] C. If the spacer 17 moves further downward, then at the stage where the first disc spring assembly 10 is compressed to the maximum or the acting force generated by the compression is greater than the acting force of the second disc spring assembly 11, the second pull rod 9 is pressed downward by the first pull rod 8 that moves downward to the maximum. At the above stage, by the downward movement of the spacer 17, the second pull rod 9 is moved downward against the acting force generated by the second disc spring assembly 11 that pushes the second pull rod 9 upward. Figure 2C It is a state where the first pull rod 8 moves to the S3 position that is lower than S1 and S2, and the second pull rod 9 is in the state of moving downward to the maximum.

[0114] At this time, as Figure 4B shown, the first ball 32 in the first through-hole 31 is allowed to move in the direction of the first recess 35 and is in a released position. The second ball 34 in the second through-hole 33 is also allowed to move in the direction of the second recess 37 and is in a released position. That is to say, the chuck holder 51 is in a state where it can be connected.

[0115] D. As Figure 2DAs shown, the chuck holder 51 is mounted on the holder mounting hole 19 of the spindle unit 2 by a prescribed control operation in the state of C. As Figure 4C shown, even if the mounting portion 53 and the draw stud 55 advance to a position deeper than the holder mounting hole 19, interference between the raised portion 56 of the draw stud 55 and the flange portion 57 of the mounting portion 53 with the first ball 32 (second ball 34) will not occur to hinder the advance.

[0116] E. In the state where the chuck holder 51 is completely mounted relative to the holder mounting hole 19 of the spindle unit 2, the spacer 17 is moved upward by a prescribed control operation. Thus, as Figure 2E shown, with the release of the weight, the strong force of the compressed second disc spring assembly 11 is released, and the second pull rod 9 is pushed upward again. Let the position at this time be S4 above S3. As the second pull rod 9 moves upward, the reduced diameter portion 58 at the rear end of the mounting portion 53 of the chuck holder 51 is clamped by the second clamping mechanism (by the second ball 34). However, at this stage, since the spacer 17 is in the middle of moving upward, the first pull rod 8 has not yet moved ( Figure 4D state).

[0117] F. As Figure 2E shown, if the spacer 17 moves further upward, with the release of the weight, the strong force of the compressed first disc spring assembly 10 is released, and the first pull rod 8 is pushed upward again. As a result, the first pull rod 8 moves relatively backward, so the first recess 35 moves, and the draw stud 55 of the chuck holder 51 (the reduced diameter corner portion at the root of the raised portion 56) is also clamped by the first clamping mechanism (by the first ball 32).

[0118] In this way, in the state where the first clamping mechanism operates and the draw stud 55 is clamped, then (actually at the moment when the spacer 17 moves upward) the first pull rod 8 is pushed upward (that is, moved backward upward), so that the draw stud 55 is pulled out backward (upward), and the claw portion 54 of the chuck holder 51 is closed. Let the position of the first pull rod 8 at this time be S5 above S4. Since the chuck holder 54 is clamped, S5 is at a position below S1. Figure 2F It shows in: In Figure 6 the states of (a) and (b), assuming that a workpiece (not shown) is clamped and the claw portion 54 has moved slightly. Therefore, here the claw portion 54 is different from Figure 7 that in (a) and (b) of

[0119] G. F. shows the operation in the case where the workpiece is not clamped, that is, when the claw portion 54 moves greatly as shown in Figure 7 the (a) and (b) ofFigure 3A As shown, compared with Figure 2F , the pulling-out amount of the traction stud 55 is larger. Therefore, the first pull rod 8 is arranged at the position S6 above S4 ( Figure 3B state).

[0120] Conversely, when the chuck holder 51 is removed from the state where the chuck holder 51 is installed on the spindle device 2, on the contrary, it is controlled such that the spacer 17 advances (descends) and sequentially reaches A. from F.(G.). In the above, for the purpose of explaining each stage of the movement, the first pull rod 8 and the second pull rod 9 are shown to act automatically for the time being. However, since the movement of the spacer 17, the release of the acting force of the first disc spring assembly 10 and the second disc spring assembly 11, etc. are all instantaneous, in fact, the actions of the first clamping mechanism and the second clamping mechanism when installing the chuck holder 51 are almost simultaneously executed.

[0121] With the above structure, the spindle unit 1 of the first embodiment can achieve the following effects.

[0122] (1) In order to clamp the chuck holder 51 having a double-layer clamped portion with an inner side and an outer side (and front and back), only by driving one cylinder device 6 as a pushing unit can the clamping be performed. Since it can be achieved only by one cylinder device 6, the spindle unit 1 and the spindle device 2 can be miniaturized and lightened.

[0123] (2) Since it is a mechanism in which only the advance and retreat of the spacer 17 connected to the piston rod 21 causes the second pull rod 9 to act via the first pull rod 8, and the first pull rod 8 advances and retreats through the first disc spring assembly 10, and the second pull rod 9 advances and retreats through the second disc spring assembly 11, the structure is simple and it is not easy to break down.

[0124] (3) Only by the acting force of the first disc spring assembly 10 can the traction stud 55 of the chuck holder 51 be clamped by the first clamping mechanism and pulled upward (backward), so that the miniaturization and lightening of the spindle device 2 can be facilitated.

[0125] (4) Since the first pull rod 8 and the second pull rod 9 are arranged in series and partially overlap, the overall length and overall width of the spindle device 2 can be miniaturized.

[0126] (5) During the clamping operation, the clamping operation is performed with a time difference in such a way that the mounting portion 53 of the chuck holder 51 is first clamped by the second clamping mechanism of the second pull rod 9, and then the traction stud 55 of the chuck holder 51 is clamped by the first clamping mechanism of the first pull rod 8. Therefore, the chuck holder 51 can be surely fixed to the holder mounting hole 19, and it is not easy to occur misoperations in the clamping of the traction stud 55, such as clamping failures where the traction stud 55 moves or vibrates and the second ball 34 is not clamped at the specified position.

[0127] (6) Since the spacer 17 retracts when the chuck holder 51 is clamped and does not come into contact with the first pull rod 8, it will not become a load on the cylinder device 6 side when the spindle device 2 rotates later, and thus the energy consumption and rotational unevenness during rotation can be reduced.

[0128] (7) Since the spindle device 2 can rotate at high speed without becoming a load on the cylinder device 6, it is applicable not only to machining by, for example, a numerically controlled machine tool but also to machining by a machining center, and a machine tool that can be arbitrarily diverted and has no restrictions can be provided.

[0129] <Second Embodiment>

[0130] The second embodiment is an example of a deformation of the first embodiment and does not use the motor device 15 and the pulleys 12, 13 as the spindle rotation mechanism 5 for rotating the spindle device 2. In addition, it is an example of not using the spacer 17 as the element for pushing the first pull rod 8. For components with the same functions as those in the first embodiment, the same reference numerals are used and their detailed descriptions are omitted.

[0131] As Figure 8 shown, the spindle unit 71 of the second embodiment includes a spindle motor device (not shown) as the spindle rotation mechanism, and the coupling 72 connected to the spindle motor device is directly connected to the spindle barrel 7 of the spindle device 2. In this way, the rotational force from the coupling 72 is transmitted to the spindle device 2. A cylinder device 73 is disposed at the upper position of the spindle unit 71 so as to surround the spindle barrel 7. The cylinder device 73 is fixed to the housing 3 side and is formed as a non-rotating part. Inside the cylinder device 73, a piston 74 is disposed so as to be able to advance and retreat in the vertical direction as a pushing unit. The piston 74 has a first port 75 and a second port 76 for introducing the working oil supplied by a hydraulic pump (not shown) formed on the side of the cylinder device 73. The piston 74 slides and moves in the vertical direction according to the supply of the working oil from the hydraulic pump device into the cylinder device 73.

[0132] A pressing pin 78 orthogonal to the axial direction of the first pull rod 8 is connected to the upper end of the first pull rod 8. Sliders 79 are fixed to both ends of the pressing pin 78.

[0133] In such a structure, the upper surface of the slider 79 presses against the bottom surface of the piston 74, so that via the pressing pin 78, the first pull rod 8 moves downward against the acting force of the first disc spring assembly 10. When the acting force generated by the maximum compression or compression of the first disc spring assembly 10 by the piston 74 is greater than the acting force of the second disc spring assembly 11, the second pull rod 9 is pressed downward by the first pull rod 8 that has moved downward to the maximum. Then, after the chuck holder 51 is housed in the holder mounting hole, the hydraulic pressure of the control cylinder device 73 is controlled to raise the piston 74 away from the slider 79, so that both the first clamping mechanism and the second clamping mechanism can operate with a time difference. In the spindle unit 71 as described above, the same effect as that of the spindle unit 1 of the first embodiment can also be achieved.

[0134] <Embodiment 3>

[0135] Embodiment 3 is an example in which the above spindle device 2 is not applied to an automatic tool changer but to a balancing machine. For components having the same functions as those in the first embodiment, the same reference numerals are used and their detailed descriptions are omitted.

[0136] As Figure 10 As described above, the main component of the balancing machine 80, that is, the spindle device 2, is placed on the base 81 in an upside-down manner different from that in the first and second embodiments. The cylinder device 6 and the spacer 17 that push the first pull rod 8 are arranged below the base 81. The motor device 15, the pulleys 12, 13, and the transmission belt 14 are housed in the base 81. A vibration sensor 82 for detecting the vibration of the spindle device 2 is arranged on the base 81. A rotary encoder 83 is provided on the output shaft 15a of the motor device 15, and the rotational position of the spindle device 2 is detected. A first measuring device 84 for measuring the balance of the chuck holder 51 mounted on the spindle device 2 is installed. A second measuring device 85 for measuring the balance of the product is installed at the upper position of the first measuring device 84.

[0137] The balancing machine 80 with the above structure calculates and computes the position of an unbalanced state (not shown) based on the information of the vibration sensor 82 and the rotary encoder 83 by a computer device. Then, by reducing this position (or conversely, the load weight), the balance of the chuck holder 51 is obtained. At this time, if the spindle device 2 is used, it is applicable to a balancing machine 80 that can easily mount and dismount the chuck holder 51 and reduce the rotational unevenness of the spindle device 2.

[0138] The above-described embodiments are merely described as specific embodiments for exemplifying the principles and concepts of the present invention. That is, the present invention is not limited to the above-described embodiments. The present invention can also be embodied in the following modified forms, for example.

[0139] · In the above-described embodiment, the chuck holder 51 having a chuck function is illustrated as an object to be clamped, but other holders may be installed in the spindle device 2. For example, as shown in (a) and (b) of Figure 9 A tool holder 60 may be used. The tool holder 60 includes a holder main body 61 and a mounting portion 62. In a mounting hole 61a in the holder main body 61, a base portion of a tool (not shown) is fixed. A stud 63 protrudes from the rear end of the mounting portion 62. The stud 63 has a non-retractable structure. At the front end of the stud 63, a raised portion 64 having a substantially elliptical shape that protrudes outward and serves as an engaging portion is integrally formed. At the front end of the mounting portion 62, a flange portion 65 that protrudes outward in a disc shape and serves as an engaging portion is integrally formed. A reduced-diameter portion 69 that serves as an engaging portion is formed between the mounting portion 62 and the flange portion 65 adjacent to the flange portion 65. In the above-described tool holder 60, the shapes of the mounting portion 62 and the stud 63 are configured to be the same as the mounting portion 53 of the chuck holder 51 and the non-retractable draw stud 55.

[0140] Since such a tool holder 60 can be mounted on the spindle device 2 at two clamped positions as described above, the tool holder 60 can be firmly mounted on the spindle device 2 from the inside and outside and from the front and back.

[0141] · The cylinder devices 6 and 73 can be either hydraulic or pneumatic.

[0142] · As a mechanism or device for applying force to the first draw bar 8 and the second draw bar 9, other spring devices may also be used. In addition, a cylinder device may also be used as a force-applying device.

[0143] · As the motor device 15, a polyphase alternating current such as a six-phase alternating current servo motor may also be used, and other motors or a motor device of a DC method instead of an alternating current may also be used.

[0144] · As the interference body that moves forward and backward in the radial direction in the clamping mechanism, the first ball 32 and the second ball 34 are used as an example above. In addition, a clamping mechanism in which a chuck or split claws are arranged and move forward and backward with radial shaking may also be used.

[0145] The present invention is not limited to the structures described in the above embodiments. The constituent elements of the above embodiments and modification examples can be arbitrarily selected and combined. In addition, any constituent elements of the respective embodiments and modification examples and any constituent elements described in the solution of the present invention or any constituent elements embodying the solution described in the present invention can be arbitrarily combined. For the above combinations, it is also desired to obtain these rights by means of amending the present application or divisional application, etc.

[0146] In addition, it is also desired to obtain these rights by changing to a design application so as to obtain the overall appearance or partial appearance, etc. The drawings depict the entire device with solid lines, but the drawings include not only the overall appearance but also the partial appearance of the partial parts of the device. For example, in the drawings, there are included certain parts of the device as partial appearance and certain parts of the device as partial appearance that are not related to the components. As the partial parts of the device, they can also be the partial components of the device or the parts of the components.

[0147] Reference Signs

[0148] 2... spindle device, 6... cylinder device as a pushing unit, 8... first pull rod, 9... second pull rod, 10... disc spring assembly as a first biasing unit, 11... disc spring assembly as a second biasing unit, 51... chuck holder as a holding member, 60... tool holder as a holding member, 56... raised portion as a first clamped portion, 58... reduced diameter portion as a second clamped portion, 73... cylinder device as a pushing unit.

Claims

1. A spindle device that is used by mounting a holder for a tool or a workpiece on the front end of the spindle. The holder has a first clamped portion and a second clamped portion that are arranged in a double layer on the inner and outer sides on its base side. The spindle device is characterized in that it includes a first drawbar and a second drawbar. The first drawbar has a first clamping mechanism at its front end side for clamping the first clamped portion of the holder, and the second drawbar has a second clamping mechanism at its front end side for clamping the second clamped portion of the holder. The first drawbar and the second drawbar are arranged in series and can move forward and backward within the spindle barrel of the spindle. The first drawbar is configured to be pressed by a pushing unit in the forward direction, so as to oppose and move forward against the acting force generated by a first biasing unit. The second drawbar is configured to be directly or indirectly pushed by the first drawbar as the first drawbar moves forward, so as to oppose and move forward against the acting force generated by a second biasing unit. When the first drawbar that moves forward by means of the pushing unit reaches a specified forward and backward position, the first clamping mechanism of the first drawbar is released, and the second clamping mechanism of the second drawbar that is pushed by the first drawbar is also released. As the pressing force generated by the pushing unit is released, the first drawbar and the second drawbar at the specified forward and backward position respectively move backward toward the base direction of the spindle barrel by the acting forces of the first biasing unit and the second biasing unit, and the first clamping mechanism of the first drawbar and the second clamping mechanism of the second drawbar operate.

2. The spindle device according to claim 1, wherein When not pressing the first drawbar, the pushing unit retracts to a position where it does not contact the first drawbar.

3. The spindle device according to claim 1 or 2, characterized in that, The acting force obtained when the second biasing unit applies force is greater than the acting force obtained when the first biasing unit applies force.

4. The spindle device according to claim 1 or 2, characterized in that, When the first drawbar moves backward from the specified forward and backward position, after the second clamping mechanism of the second drawbar operates, the first clamping mechanism of the first drawbar operates.

5. The spindle device according to claim 1 or 2, characterized in that, The first drawbar has an outer peripheral surface that contacts the inner peripheral surface of the second drawbar, and is guided by the inner peripheral surface and the outer peripheral surface to slide forward and backward.

6. The spindle device according to claim 1 or 2, characterized in that The first clamping mechanism and the second clamping mechanism are arranged at positions offset in the front and rear directions.

7. The spindle device according to claim 1 or 2, characterized in that, The first clamping mechanism has an interfering body that moves forward and backward in the radial direction of the spindle. In a state where the first drawbar is arranged at a first forward and backward position, the interfering body that clamps the first clamped portion is in a position facing a receiving portion formed on the inner peripheral surface of the second drawbar, so that the first clamping mechanism is released.

8. The spindle device according to claim 7, characterized in that, The second clamping mechanism has an interfering body that moves forward and backward in the radial direction of the spindle. In a state where the first drawbar is arranged at the first forward and backward position, the interfering body that clamps the second clamped portion is in a position facing a receiving portion formed on the inner peripheral surface of the spindle barrel, so that the second clamping mechanism is released.

9. The spindle device according to claim 1 or 2, characterized in that, The holder is mounted in a holder mounting hole formed at the front end of the spindle barrel.

10. The spindle device according to claim 1 or 2, characterized in that, The holding member for the workpiece is configured such that the first clamped portion is formed on a rod member capable of advancing and retreating, and in a state where the second clamping mechanism applies an action to the holding member mounted on the front end of the spindle, the rod member is pulled out via the first clamped portion, so that the workpiece in the released state is clamped, and by advancing the first pull rod, the rod member is pushed back to release the workpiece in the clamped state.

11. The spindle device according to claim 1 or 2, characterized in that, The first biasing unit and the second biasing unit are compression spring devices, and bias the first pull rod and the second pull rod in the retreat direction.

12. A machine tool, characterized in that, A spindle device according to claim 1 or 2 is mounted.

13. A balancing machine, characterized in that, A spindle device according to claim 1 or 2 is mounted.

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