JP3596161B2 - Spindle device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a spindle device for a machine tool or the like.
[0002]
[Prior art]
In a spindle device for a machine tool such as a machining center (MC), as shown in FIG. 5, a tapered hole 2 for mounting a tool is formed at a front end of a spindle shaft 1, and a tapered shank portion of a tool holder 3 is formed in the tapered hole 2. 4 is fitted so that a predetermined tool is mounted.
[0003]
A draw bar 7 having a tool holder holding portion 6 at its tip for pulling in the pull stud 5 of the tool holder 3 and fixing the tool holder 3 to the spindle shaft 1 is inserted into the shaft center portion of the spindle shaft 1. A disc spring 8 is externally inserted into the draw bar 7 and housed in a shaft hole 1A provided in the spindle shaft 1. Further, in order to remove the tool holder 3, an axial load is applied to the rear end of the draw bar 7 using a hydraulic cylinder or the like (not shown) to compress the disc spring 8.
[0004]
[Problems to be solved by the invention]
However, recently, the spindle device tends to rapidly increase in speed, and as described above, in the system in which the draw bar 7 is pulled in by using the elastic force of a large number of disc springs 8 when a tool is mounted, the disc spring 8 is rotated at a high speed. There is a problem that the vibration of the device is increased due to the influence. Moreover, in order to make the disc spring 8 bend, a certain clearance is required between the inner peripheral surface of the shaft hole of the spindle shaft 1 and the outer peripheral surface of the draw bar. There is a limit.
[0005]
The present invention has been made in order to solve such a disadvantage, and an object of the present invention is to provide a low-cost spindle device that can easily increase the natural frequency of a drawbar and can cope with high-speed rotation.
[0006]
[Means for Solving the Problems]
In order to achieve this object, a spindle device according to claim 1 has a taper hole at a shaft end for attaching a tool holder, and a spindle shaft rotatably supported by a housing via a bearing; A tool holder holding portion for engaging with the pull stud is provided at the front end, and a draw bar driving end is provided at the rear end, and is axially movable in an axial hole formed in the spindle shaft so as to communicate with the tapered hole. An inserted draw bar, a number of disc springs that are inserted into the draw bar inside the shaft hole and urge the draw bar rearward, and are connected to the draw bar driving end to resist the urging force of the disc spring. in the spindle device provided with a driving means for moving forward, and fitted around the sleeve formed smaller in diameter than the rear end tip drawbar tip from disc spring side of the sleeve above To support the load in the axial direction by the disc spring by the surface is brought into contact with the stepped portion of the shaft hole, characterized by being adapted to support the drawbar by a rear end of the sleeve.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory sectional view for explaining a spindle device according to a first embodiment of the present invention . In this embodiment, the same reference numerals are given to the same parts as those in the conventional example, and the description is omitted.
[0009]
In this spindle device, two sleeves 9a and 9b as support members are externally inserted into a draw bar 7 on the tip side of a disc spring 8 while being spaced apart from each other in the axial direction, and the outer peripheral surfaces of the respective sleeves 9a and 9b and the inside of a shaft hole. The radial clearance with the peripheral surface is reduced. As a result, the natural frequency of the drawbar 7 and, consequently, the natural frequency of the entire spindle shaft are increased so as to be able to cope with high-speed rotation. In the drawing, reference numeral 9c denotes a retaining ring for locking the sleeve 9a on the distal end side in the shaft hole 1A.
[0010]
Next, a spindle device according to a second embodiment of the present invention will be described. FIG. 2 is an explanatory sectional view for explaining the spindle device. This spindle device is suitable for a type with a long spindle shaft, and is used to reduce the gap at a deep position in the shaft hole (for example, to reduce the coaxiality and dimensional tolerance as in the case of grinding a deep hole). This eliminates the need for processing performed by management.
[0011]
First, the configuration will be described. The spindle shaft 10 of the spindle device is inserted through a housing 11 and has a front end (left end) having a plurality of (two in the figure) ball bearings 12 and a rear end ( The right end is rotatably supported horizontally by a single roller bearing 13. The housing 11 includes a cylindrical outer cylinder 14, a front lid 15 fixed to a front end face of the outer cylinder 14, and a rear lid 16 fixed to a rear end face of the outer cylinder 14. A mounting flange 17 for mounting the spindle device to a spindle mounting machine base of a machine tool or the like is formed at a substantially central outer peripheral portion of the outer cylinder 14 in the axial direction.
[0012]
An outer spacer 18 is interposed between two adjacent outer rings 12a of the two ball bearings 12 that support the front end of the spindle shaft 10. The outer race 12a of the front ball bearing 12 at the front end is pressed by the front lid 15, and the outer race 12a of the rear ball bearing 12 at the front end is received by the step 19 formed on the inner periphery of the outer cylinder 14. As a result, each outer ring 12a is fixedly disposed on the inner peripheral portion of the outer cylinder 14. An inner spacer 20 is interposed between the adjacent inner rings 12b of each ball bearing 12. The inner ring 12b of the ball bearing 12 on the rear side of the front end portion is received by the step portion 21 of the spindle shaft 10, and the inner ring 12b of the ball bearing 12 on the front end side is an inner ring presser fitted to the outer peripheral portion of the spindle shaft 10. The inner ring 12b is fixedly arranged on the outer peripheral portion of the spindle shaft 10.
[0013]
On the other hand, the outer ring 13a of the roller bearing 13 that supports the rear end of the spindle shaft 10 has its front side face received by the stepped portion 23 of the rear lid 16 and its rear side face is pressed by the outer ring presser 24. The outer ring 13a is fixed to the inner peripheral surface of the rear lid 16. The inner ring 13b of the roller bearing 13 has its front side face received by a ring-shaped member 25 externally fitted and fixed to the spindle shaft 10, and its rear side face is pressed by a ring-shaped inner ring pressing lid 26. It is fixed to the outer peripheral surface of the spindle shaft 10.
[0014]
The rotor 27 of the built-in motor M is fixed to the outer peripheral surface of the central portion of the spindle shaft 10 by interference fit. A stator 28, which is coaxially arranged so as to face the rotor 27 circumferentially, is fixed to the inner circumferential surface of the outer cylinder 14 via a stator sleeve 29.
[0015]
The spindle shaft 10 has a taper hole 30 for mounting a tool whose diameter gradually decreases from the front end face toward the rear end side, and a shaft hole 31 that passes through the tapered hole 30 to the rear end of the spindle shaft 10. It is formed along the axis of ten.
[0016]
A taper shank 33 of a tool holder 32 for holding a tool (not shown) is fitted in the tapered hole 30.
A pull stud 34 having a small-diameter neck 34a and a large-diameter head 34b is attached to the tip of the tapered shank 33, and the pull stud 34 is axially movable in the shaft hole 31. It is removably gripped by an inserted sleeve 35 via a ball 36. Here, the sleeve 35 and the ball 36 constitute a tool holder holding portion of the present invention.
[0017]
A plurality of balls 36 are arranged in the circumferential direction and held by the sleeve 35 so as to be able to retreat radially outward. A drive draw bar 37 for driving the sleeve 35 to move in the axial direction is connected to the rear end of the sleeve 35. The draw bar 37 protrudes from the rear end of the spindle shaft 10 through the inside of the shaft hole 31, and the protruding end is a draw bar drive end 37a. A piston (not shown) as driving means is connected to the draw bar driving end 37a.
[0018]
When the drive of the piston is released, the draw bar 37 is retracted by the urging force of a large number of disc springs 39 externally inserted into the draw bar 37 in the disc spring storage hole 38 provided in the shaft hole 31, and the sleeve 35 is also moved. fall back. At this time, the ball 36 is pushed by the inner peripheral surface of the shaft hole 31 while moving from the relatively large-diameter space 31a of the shaft hole 31 adjacent to the tapered hole 30 to the small-diameter space 31b on the rear end side, so that the ball 35 The ball 36 protrudes radially inward from the peripheral surface, whereby the ball 36 grips the head 34b of the pull stud 34, and the tool holder 32 and thus the tool are attached.
[0019]
When the piston is driven, the draw bar 37 moves forward against the urging force of the disc spring 39, and the sleeve 35 moves forward. At this time, the ball 36 moves from the small-diameter space 31b provided in the shaft hole 31 to the large-diameter space 31a and retreats radially outward and retracts from the inner diameter surface of the sleeve 35. The grip of the portion 34b is released, and the tool holder 32 and thus the tool can be removed. In the figure, reference numeral 40 denotes a holding ring inserted from the rear end of the spindle shaft 10 into the shaft hole 31 to hold the disc spring 39, and 41 denotes a set nut for fixing the holding ring 40 to the spindle shaft 10.
[0020]
Further, a sleeve 42 is externally fitted to the draw bar 37 on the tip side of the disc spring 39. The distal end 43 of the sleeve 42 is formed smaller in diameter than the rear end 44, and the distal end 43 is inserted into a small-diameter hole 45 smaller in diameter than the disc spring storage hole 38, and the distal end surface thereof is formed in a step 46. The abutment supports the load in the axial direction by the disc spring 39. On the other hand, the rear end 44 of the sleeve 42 is located in the disc spring receiving hole 38 so that a radial gap between the outer peripheral surface and the inner peripheral surface of the disc spring receiving hole 38 is made as small as possible. Support the drawbar 37. The support and the above-described support in the axial direction increase the natural frequency of the drawbar 37 and thus the entire spindle shaft 10, thereby enabling the spindle shaft 10 to cope with high-speed rotation.
[0021]
Further, in order to fit the taper shank portion 33 of the tool holder 32 into the taper hole 30 of the spindle shaft 10, the piston is driven and the draw bar 37 is moved forward against the urging force of the disc spring 39, whereby the sleeve is moved. 35 is advanced to retract the ball 36 radially outward. Then, in this state, the taper shank portion 33 of the tool holder 32 carried by the ATC is inserted into the taper hole 30 of the spindle shaft 10.
[0022]
Next, the tool holder 32 is further pushed in so that the tapered shank 33 is fitted into the tapered hole 30, and the pull stud 34 at the tip of the tapered shank 33 is inserted into the sleeve 35. When the driving of the piston is released in this state, the draw bar 37 is retracted in the shaft hole 31 by the urging force of the disc spring 39, the sleeve 35 is retracted, and the ball 36 is moved backward from the large-diameter space 31a of the shaft hole 31. While moving to the small-diameter space 31b on the end side, it is pushed by the inner peripheral surface of the shaft hole 31 and protrudes radially inward from the inner peripheral surface of the sleeve 35, whereby the ball 36 grips the head 34b of the pull stud 34. Then, the tool holder 32 and thus the tool are mounted. When the drawbar 37 is mounted, the drawbar 37 is urged to the rear end side by the disc spring 39, so that the tool holder 32 is pulled rearward, whereby the outer peripheral surface of the taper shank portion 33 and the inner peripheral surface of the taper hole 30 are formed. The surfaces come into close contact with each other by pressing.
[0023]
As described above, in this embodiment, a portion for reducing the radial gap and supporting the draw bar 37 is provided at the shallow position of the shaft hole 31, and the portion of the shaft hole 31 formed by the disc spring 39 is provided at the deep position. Is provided so as to increase the natural frequency of the draw bar 37, so that it is not necessary to perform a difficult process for reducing the radial gap at a deep position of the shaft hole. As a result, It is possible to easily increase the natural frequency of the drawbar and to provide a spindle device capable of coping with high-speed rotation at low cost.
[0024]
FIG. 3 shows a third embodiment of the present invention . The same parts as those in the embodiment of FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. This embodiment is an example in the case where the number of disc springs 39 is larger than that of the embodiment of FIG. 2. In such a case, one or more thin sleeves 50 (see FIG. In this case, two drawers are interposed to reduce the radial gap between the outer peripheral surface of the sleeve 50 and the inner peripheral surface of the disc spring storage hole 38 so as to support the drawbar 37 at multiple points. .
[0025]
【Example】
FIG. 4 shows a type in which the spindle device shown in FIG. 2 is elongated, and is structurally exactly the same as FIG. 2 except that it is elongated. On the other hand, FIG. 5 shows a conventional spindle device without the sleeve 42, and is structurally similar except that it does not have the sleeve 42 and the small-diameter hole portion 45 into which the distal end 43 of the sleeve 42 is inserted. This is exactly the same as FIG.
[0026]
4 and drawbar natural frequency calculated values in Figure 4 of the spindles device where the natural frequencies were calculated drawbar of each spindle device of Figure 5 654.316Hz, drawbar natural frequency calculations in the conventional spindle device of FIG. 5 The value was 231.150 Hz.
[0027]
【The invention's effect】
As is apparent from the above description, according to the present invention , it is possible to easily increase the natural frequency of the drawbar and to provide a spindle device capable of coping with high-speed rotation at a low cost. Can be
[0028]
In addition, when raising the natural frequency of the drawbar, it is not necessary to perform difficult processing to reduce the radial gap at the deep position of the shaft hole, so it is easy to use the drawbar even when the spindle shaft is long. This makes it possible to provide a spindle device capable of coping with high-speed rotation at a low cost.
[Brief description of the drawings]
FIG. 1 is an explanatory sectional view illustrating a spindle device according to a first embodiment of the present invention .
FIG. 2 is an explanatory cross-sectional view for explaining a spindle device according to a second embodiment of the present invention .
FIG. 3 is an explanatory sectional view for explaining a spindle device according to a third embodiment of the present invention .
FIG. 4 is a sectional view of a spindle device used for comparison with a conventional example.
FIG. 5 is an explanatory sectional view for explaining a conventional spindle device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Spindle shaft 1A ... Shaft hole 2 ... Taper hole 3 ... Tool holder 4 ... Taper shank part 5 ... Pull stud 6 ... Tool holder holding part 7 ... Drawbar 8 ... Disc springs 9a and 9b ... Sleeve (support member)
DESCRIPTION OF SYMBOLS 10 ... Spindle shaft 11 ... Housing 12, 13 ... Bearing 30 ... Tapered hole 31 ... Shaft hole 32 ... Tool holder 34 ... Pull stud 35 ... Sleeve (tool holder holding part)
36 Ball (tool holder holding part)
37a: Drawbar drive end 37: Drawbar 39: Disc spring 42: Sleeve

Claims (1)

A spindle shaft having a tapered hole at the shaft end for mounting a tool holder, rotatably supported by a housing via a bearing, and a tool holder holding portion that engages with a pull stud of a tool holder at a tip and draw bar drive A drawbar having an end at a rear end, a drawbar inserted movably in the axial direction in a shaft hole formed in the spindle shaft so as to communicate with the tapered hole, and a drawbar inserted in the shaft hole in the shaft hole. A spindle device comprising: a plurality of disc springs for urging the draw bar rearward; and drive means connected to the draw bar drive end to move the draw bar forward against the urging force of the disc spring.
A sleeve whose distal end is formed smaller in diameter than the rear end is externally fitted to the draw bar on the distal end side of the disc spring, and the distal end surface of the sleeve is brought into contact with the stepped portion of the shaft hole, so that the axial direction by the disc spring is A spindle device for supporting a load and supporting the drawbar by a rear end of the sleeve.

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