JP3776700B2 - Spindle device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spindle device of a machine tool such as a machining center provided with an ATC (automatic tool changer).
[0002]
[Prior art and problems]
In this type of machine tool spindle device, as disclosed in, for example, Japanese Patent Publication No. 7-106534, a draw bar can be moved back and forth in the axial direction (longitudinal direction) in a spindle rotatably supported by a housing. And the draw bar is moved forward and backward by the expansion and contraction operation of the spring device and the hydraulic cylinder, thereby enabling the tool (or the tool holder holding the tool) to be clamped / unclamped with respect to the tip of the spindle.
[0003]
In the main shaft device, when the piston of the hydraulic cylinder is stroked to the extension side (the front end side of the main shaft), the front end portion of the piston eventually comes into contact with the rod end of the draw bar, and the draw bar moves forward against the biasing force of the spring device. The collet chuck assembled at the tip of the main spindle is released by this movement (extrusion), and the tool or tool holder is unclamped. On the other hand, when the piston of the hydraulic cylinder is stroked to the contraction side (rear end side of the main shaft) with the tool or holder inserted at the front end of the main shaft, the collet chuck is engaged by the retraction (retraction) of the draw bar by the spring device. Operates to clamp the tool or tool holder.
[0004]
[Problems to be solved by the invention]
By the way, in the conventional spindle device, a spring member such as a disc spring constituting the spring device is wound on the draw bar with a minute gap between the inner diameter portion and the outer peripheral surface of the draw bar. Generally, at the time of assembly, taps and the like are embedded in the end face of the main shaft to balance the main shaft.
[0005]
However, due to the centrifugal force caused by the rotation of the spindle accompanying the increase in machine speed and frequent expansion and contraction during tool change (drawbar clamping / unclamping), the spring member is misaligned (shifted in the radial direction of the spindle) and out of phase. There has been a problem that the main shaft vibrates due to a large change in the balance of the main shaft. In other words, the machining accuracy is reduced due to the vibration of the spindle, the tool life is shortened, and the working environment is deteriorated due to the generation of vibration noise.
[0006]
The present invention has been proposed in view of the problems associated with the above-described conventional spindle device, and provides a spindle device capable of suppressing the occurrence of vibration by reducing changes in the balance of the spindle due to the displacement of the spring member. With the goal.
[0007]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the main spindle device according to the first aspect of the present invention has a main shaft that is rotatably supported by a housing, on the side where the draw bar can be moved back and forth in the axial direction and always retracted by a spring member. An end of a spring member wound on the draw bar in the spindle device that allows the tool to be clamped and unclamped by inserting the biased state and moving the draw bar forward and backward by driving means. And a contact surface between the spring member and the end of the support member that supports the spring member in the main shaft axis direction on the draw bar are tapered to prevent the spring member from being displaced.
[0008]
Further, the spindle device of the invention according to claim 2 is in a state in which the draw bar can be moved forward and backward in the axial direction and urged to the side always retracted by the spring member in the spindle rotatably supported by the housing. In the spindle device that enables clamping and unclamping of the tool with respect to the tip of the spindle by inserting and moving the draw bar forward and backward by the driving means, the end of the spring member wound on the draw bar and the spring member are Friction increasing means is interposed on the contact surface with the end of the supporting member that is supported on the draw bar in the direction of the main shaft , thereby preventing the spring member from shifting.
[0009]
According to a third aspect of the present invention, there is provided a main shaft device in a state in which the draw bar can be moved back and forth in the axial direction in the main shaft rotatably supported by the housing and urged toward the side always retracted by the spring member. In the spindle device that enables clamping and unclamping of the tool with respect to the tip of the spindle by inserting and moving the draw bar forward and backward by the driving means, the end of the spring member wound on the draw bar and the spring member are the contact surface of the end portion of the bearing member which supports the spindle axis on the drawbar while tapering, interposed friction-increasing means before Kise' touch surface, and characterized in that to prevent the displacement of the spring member To do.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0011]
[Example]
FIG. 1 is a longitudinal sectional view of a spindle device according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part, and FIG. 3 is an explanatory view of a compression coil spring.
[0012]
As shown in FIG. 1, a spindle head 1 of a machining center equipped with an ATC (automatic tool changer) has a housing 2 and an intermediate member 13.
[0013]
The main shaft 5 is rotatably accommodated and held in the housing 2 and the intermediate member 13 via the bearing 3 and the bearing 4. A tool holder 6 having a pull stud 6 a is pulled into the tip of the main shaft 5, and a collet chuck 7 that can rotate integrally with the main shaft 5 is assembled. The main shaft 5 is rotationally driven by a motor (built-in motor) 23.
[0014]
A draw bar 9 is inserted into the central through hole 8 of the main shaft 5, and the draw bar 9 is screwed into a nut 10 slidable in the longitudinal direction in the central through hole 8, so that the central axis is the main shaft. The centering is held so as to coincide with the center axis of 5. A rod end 12 that moves integrally with the draw bar 9 in the longitudinal direction is fitted behind the nut 10 of the draw bar 9.
[0015]
The draw bar 9 is fixed (clamped) integrally with the spindle 5 by holding the tool holder 6 (not shown) by pulling the pull stud 6a of the tool holder 6 with the collet chuck 7 at the tip. It has become.
[0016]
A pair of left and right-handed front and rear compression coil springs 14a, 14b are wound around the outer periphery of the draw bar 9 in front of the nut 10 via three cylindrical spacers 15a, 15b, 15c. Is always urged to the pull-in side.
[0017]
In order to release (unclamp) the tool holder 6, a hydraulic cylinder 16 provided behind the main shaft 5 is used. The hydraulic cylinder 16 is configured such that a piston 18 is slidably accommodated in head portions 17a and 17b integrally assembled with a rear portion of the housing 2 (strictly, an intermediate member 13).
[0018]
Then, when the piston 18 is stroked to fill the initial gap C on the extending side (the tip side of the main shaft 5) by pressure oil from a hydraulic supply source (not shown), the front end portion of the piston 18 eventually becomes the rod end 12 of the draw bar 9. The draw bar 9 is moved forward (extruded) against the urging force of the compression coil springs 14a and 14b by contact, and the collet chuck 7 assembled at the tip of the main shaft 5 is thereby released to unclamp the tool holder 6. To do.
[0019]
On the other hand, when the piston 18 is stroked to the contraction side (rear end side of the main shaft 5) with the tool holder 6 inserted in the tip of the main shaft 5, the draw bar 9 is moved backward by the urging force of the compression coil springs 14a and 14b ( The tool holder 6 is clamped by the collet chuck 7 being engaged by pulling in.
[0020]
In this embodiment, as shown in FIGS. 2 and 3, the compression coil springs 14 a and 14 b wound around the draw bar 9 and a supporting member that supports the compression coil springs 14 a and 14 b on the draw bar 9. The contact surfaces of the spacers 15a, 15b and 15c are tapered, and an O-ring 22 as a friction increasing (generating) means is embedded in the contact surfaces of the spacers 15a, 15b and 15c, and the compression coil springs 14a and 14b are embedded. It is designed to prevent deviation.
[0021]
More specifically, the end surfaces of the spacers 15a, 15b, and 15c in contact with the compression coil springs 14a and 14b are formed on the tapered surface 19 having a predetermined taper angle θ (θ≈5 °) that is recessed on the inner diameter side, and the compression coil springs. Tapered surface portions 20a and 20b having a predetermined taper angle θ (θ≈5 °) protruding from the inner diameter side are formed at the ends of the spacers 14a and 14b in contact with the spacers 15a, 15b and 15c.
[0022]
Unlike the other spacers 15a and 15b, the latter-stage spacer 15c is fixed to the draw bar 9 with screws 21. As a result, the torsional torque (left-handed spring is left and right-handed spring is right) generated when the compression coil springs 14a and 14b are contracted is canceled by the middle stage spacer 15b being easily slid. .
[0023]
With this configuration, the compression coil springs 14a and 14b wound on the draw bar with a minute gap between the inner diameter portion and the outer peripheral surface of the draw bar can be provided even after the balance of the main shaft 5 is reached. Under the action of centrifugal force due to high-speed rotation of the spindle 5 and frequent expansion and contraction during tool change (clamping / unclamping movement of the draw bar 9), misalignment (radial deviation of the spindle) and phase deviation (circle of the spindle) (Circumferential displacement) is attracted.
[0024]
However, in this embodiment, even under the above-described action, a so-called wedge action is caused by contact between the tapered surfaces 19 of the spacers 15a, 15b, and 15c and the tapered surface portions 20a and 20b of the compression coil springs 14a and 14b. Misalignment of the springs 14a and 14b is prevented. Further, the O-ring 22 embedded in the tapered surface 19 of the spacers 15a, 15b, 15c increases the coefficient of friction between the contact surfaces of both members, and in particular prevents the phase shift of the compression coil springs 14a, 14b.
[0025]
As a result, the change in the balance of the main spindle 5 is reduced, and the occurrence of vibration is effectively suppressed. Therefore, the machining accuracy in the machining center is improved, the tool life is increased, and the working noise is reduced by reducing the vibration noise. Deterioration is avoided.
[0026]
Needless to say, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. For example, as a friction increasing means, a detent key indicated by reference numeral 30 in FIG. 3 may be used in place of the O-ring 22, or a diamond coating may be applied to the contact surfaces of both members. Further, when a large number of disc springs are used as the spring members instead of the compression coil springs 14a and 14b, the phase shift is not induced, so that the friction increasing means is not particularly necessary. The spindle device of the present invention can also be applied to a spindle device of a machine tool that does not have an ATC or a built-in motor.
[0027]
【The invention's effect】
As described above in detail, according to the main spindle device of the first aspect of the present invention, the draw bar can be moved back and forth in the axial direction in the main shaft rotatably supported by the housing and always retracted by the spring member. In the spindle device that enables clamping and unclamping of the tool with respect to the tip of the spindle by inserting and driving the draw bar in a state of being biased by the driving means , the end of the spring member wound on the draw bar the contact surface of the end portion of the bearing member which supports the spindle axis direction parts and said spring member on said drawbar and tapered, so is characterized by preventing deviation of the spring member, the core of the particular spring members Deviation (radial deviation of the main shaft) can be effectively prevented, and the change in the balance of the main shaft can be reduced to suppress the occurrence of vibration. As a result, machining accuracy is improved, tool life is increased, and work environment deterioration can be avoided by reducing vibration noise.
[0028]
According to the spindle device of the second aspect of the present invention, the draw bar can be moved forward and backward in the axial direction and urged to the side always retracted by the spring member in the spindle rotatably supported by the housing. In the spindle device that enables clamping and unclamping of the tool with respect to the tip of the spindle by inserting and moving the draw bar by the driving means, the end of the spring member wound on the draw bar and the spring member Since the friction increasing means is interposed on the contact surface with the end portion of the carrying member supported in the main shaft direction on the draw bar to prevent the spring member from shifting, in particular, the phase shift of the spring member ( (Spindle circumferential deviation) can be effectively prevented, and the change in the balance of the main shaft can be reduced to suppress the occurrence of vibration. As a result, machining accuracy is improved, tool life is increased, and work environment deterioration can be avoided by reducing vibration noise.
[0029]
According to the spindle device of the third aspect of the invention, the draw bar can be moved forward and backward in the axial direction and urged to the side always retracted by the spring member in the spindle rotatably supported by the housing. In the spindle device that enables clamping and unclamping of the tool with respect to the tip of the spindle by inserting and moving the draw bar by the driving means, the end of the spring member wound on the draw bar and the spring member wherein the contact surface between the end portion of the bearing member which supports the spindle axis on the drawbar while tapering, interposed friction-increasing means before Kise' touch surface to prevent displacement of the spring member Therefore, both the center deviation and the phase deviation of the spring member can be effectively prevented, and the change in the balance of the main shaft can be reduced to suppress the occurrence of vibration. As a result, machining accuracy is improved, tool life is increased, and work environment deterioration can be avoided by reducing vibration noise.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a spindle device according to an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of the main part of the same.
FIG. 3 is an explanatory view of a compression coil spring.
[Explanation of symbols]
1 Spindle head 2 Housing 3 Bearing 4 Bearing 5 Spindle 6 Tool holder 7 Collet chuck 8 Center through hole 9 Draw bar 10 Nut 12 Rod end 13 Intermediate members 14a, 14b Compression coil springs 15a, 15b, 15c Spacer 16 Hydraulic cylinders 17a, 17b Head Portion 18 Piston 19 Tapered surface 20a, 20b Tapered surface portion 21 Screw 22 O-ring 23 Motor 30 Key C Initial gap

Claims (3)

The draw bar is inserted into the main shaft rotatably supported by the housing in a state where the draw bar can be moved forward and backward in the axial direction and is always urged by the spring member, and the draw bar is moved forward and backward by the driving means. in, the spindle apparatus capable of clamping and unclamping of the tool relative to the spindle tip end of the support member for supporting the end portion and said spring member wound around the spring member on the drawbar to the spindle axis on the drawbar A spindle device characterized by tapering a contact surface with a portion to prevent displacement of the spring member. The draw bar is inserted into the main shaft rotatably supported by the housing in a state where the draw bar can be moved forward and backward in the axial direction and is always urged by the spring member, and the draw bar is moved forward and backward by the driving means. in, the spindle apparatus capable of clamping and unclamping of the tool relative to the spindle tip end of the support member for supporting the end portion and said spring member wound around the spring member on the drawbar to the spindle axis on the drawbar A spindle device characterized in that a friction increasing means is provided on a contact surface with the portion to prevent the spring member from shifting. The draw bar is inserted into the main shaft rotatably supported by the housing in a state where the draw bar can be moved forward and backward in the axial direction and is always urged by the spring member, and the draw bar is moved forward and backward by the driving means. in, the spindle apparatus capable of clamping and unclamping of the tool relative to the spindle tip end of the support member for supporting the end portion and said spring member wound around the spring member on the drawbar to the spindle axis on the drawbar the contact surface between the parts as well as tapering, interposed friction-increasing means before Kise' touch surface, the spindle device characterized by preventing deviation of the spring member.

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