JPH11239906A - Spindle drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly speed up the operation for making a tool an unclamping state. SOLUTION: A spindle drive device for rotatively driving a tool by a spindle rotated by rotational driving force of a motor comprises a rod 3 moving a clamping position where the spindle 4 holds the tool and an unclamping position where the holding of the tool is released, a piston member 7 accommodated in a pressure chamber 6 as well as altering the position of the rod 3 to the clamping position or the unclamping position, pressure giving means injecting a pressure medium into the pressure chamber so as to alter the position of the piston member 7 to the clamping position or the unclamping position, first spring means 8 energizing the rod 3 to the side of the clamping position, and second spring means 9 energizing the piston member 7 to the side of the unclamping position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle driving device in which a tool holder for holding a tool is mounted on a spindle and rotated by a rotational driving force of a motor. More specifically, the present invention relates to a mechanism for changing a state in which a spindle clamps a tool and a state in which the tool is unclamped.

[0002]

2. Description of the Related Art In a machining center for machining a workpiece while automatically exchanging a plurality of tools, a spindle driving device 10 for rotating a spindle 103 having a tool holder 106 holding a tool 111 as shown in FIG.
One. The spindle driving device 101 connects the motor 102 and the spindle 103 with a pulley 104 and a belt 105, and transmits the rotational drive of the motor 102 to the spindle 103.

The spindle driving device 101 includes a rod 107 which moves to a clamp position where the spindle 103 holds the tool holder 106 and an unclamping position where the holding of the tool holder 106 is released, and a position where the rod 107 is clamped or unclamped. A piston member 109 for changing the position, a pressure applying means (not shown) for injecting a pressure medium such as oil into the pressure chamber 108 to change the position of the piston member 109 to a clamp position or an unclamping position,
It has a number of disc springs 110 for urging the rod 107 toward the clamp position.

When the tool holder 106 mounted on the spindle driving device 101 is replaced, the pressure applying means is operated to move the piston member 109 to the unclamping position. The piston member 109 moves the rod 107 to the unclamping position while receiving the reaction force of the disc spring 110. Thereby, the collet 112 of the spindle 103 is loosened, the pull stud 113 of the tool holder 106 is released, and the tool holder 106 can be removed. And
Next, after inserting the tool holder 106 holding the tool 111 to be used into the spindle 103, the pressure applying means is operated to move the piston member 109 to the clamp position. The movement of the piston member 109 releases the disc spring 110 to move the rod 107 to the clamp position.
Thereby, the collet 112 of the spindle 103 is tightened, the pull stud 113 of the tool holder 106 is chucked, and the tool holder 106 can be held.

[0005] Between the spindle 103 and a tip side wall 114 forming a pressure chamber 108 on the spindle 103 side (tip side) of the piston member 109, the tip side wall 1 is located.
A stopper 115 and a hook member 116 that are caught when the spindle 14 and the spindle 103 are separated from each other and prevent them from being detached from each other are attached. As a result, the reaction force generated between the piston member and the rod 107 when the piston member 109 is moved to the unclamping position side (distal side) is reduced by the proximal side wall 117, the cylinder peripheral wall 118, the distal side wall 114, and the hook member. It can be received by 116 and stopper 115.

When the piston member 109 is at the clamp position, a slight oil pressure is applied to the pressure chamber 108 on the spindle 103 side in order to maintain the piston member 109 at the clamp position (base end side). Therefore, a gap S1 can be provided between the piston member 109 and the rod 107.

Further, when the piston member 109 is in the clamp position, the proximal end side wall 117 and the cylinder peripheral wall 118
The tip side wall 114 is urged toward the spindle 103 by an urging spring 119 formed of a compression coil spring. Therefore, a gap S2 can be provided between the hook member 116 and the stopper 115.

As a result, the rotating rod 107 and the non-rotating piston member 109 and the hook member 116 are kept out of contact with each other to prevent the generation of frictional heat.

[0009]

However, in the spindle drive device 101 described above, the rod 107 is always urged toward the clamp position by the disc spring 110, whereas the piston member 109 is urged except for the hydraulic pressure. In order to change the rod 107 from the clamp position to the unclamped position, the piston 107 is moved only by the urging force of the disc spring 110 to change the rod 107 from the unclamped position to the clamp position. The spring 109 is moved by a force obtained by subtracting the urging force of the disc spring 110 from the urging force of the hydraulic pressure applied to the spring 109. For this reason, the rod 107
Is moved to the unclamping position is smaller than the force to move the to the clamping position.

When the piston member 109 is in the clamp position, a slight oil pressure is applied to the pressure chamber 108 on the spindle 103 side to provide a gap S1 with the rod 107. In order to change the oil pressure, the oil injection must be stopped once, and then the oil must be injected into the pressure chamber 108 on the opposite side. This oil pressure switching is required. Will occur.

Further, when the rod 107 is in the unclamping position, the rod 107 and the piston member 109 are in contact with each other, so that the rod 107 moves immediately when the piston member 109 moves, whereas the rod 107 moves to the clamping position. Sometimes, the rod 107 and the piston member 10
9, the gap S1 must be filled before the rod 107 moves even if the piston member 109 moves, resulting in a time lag.

[0012] For these reasons, the unclamping time is longer than the clamping time, so that it has been difficult to reduce the tool change time. For this reason, it has been difficult to increase the speed of work processing.

Here, when air having a lower propagation speed than oil is used as the pressure medium, the time lag for switching the direction in which the air pressure acts on the piston member 109 becomes large, and the moving speed of the rod 107 becomes slow. The overall speed cannot be improved as the timing varies.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a spindle driving device that speeds up the operation of bringing a tool into an unclamped state.

[0015]

In order to achieve the above object, according to the present invention, there is provided a spindle driving apparatus in which a tool is driven to be rotated by a spindle rotated by a rotation driving force of a motor. A rod that moves to a clamping position for holding the tool and an unclamping position for releasing the holding of the tool, a piston member that is housed in the pressure chamber and changes the position of the rod to the clamping position or the unclamping position, and pressurizes the pressure medium. Pressure applying means for changing the position of the piston member to the clamp position or the unclamping position by injecting into the chamber, first spring means for urging the rod toward the clamp position, and urging the piston member toward the unclamped position And second spring means.

Therefore, when changing the rod from the clamp position to the unclamping position in order to change the tool,
The rod is moved while receiving the reaction force of the first spring means by the combined force of the pressure of the pressure medium acting on the piston member and the urging force of the second spring means. Therefore, when the rod is moved to the unclamping position, the urging force by the second spring means can be applied as compared with the conventional case, so that the unclamping force is increased to speed up the movement of the rod to the unclamping position. Can be.

Further, when switching the pressure medium to move the piston member from the clamp position to the unclamping position, the second spring means urges and moves the piston member toward the unclamping position. For this reason, the piston member can move during the time lag due to the initial response delay in switching the pressure medium, so that the rising time of the movement of the rod to the unclamping position can be shortened and the speed can be increased.

Further, when the rod is in the clamp position, there is a gap between the rod and the piston member, so that the first
There is no interference between the spring means and the second spring means. Therefore, all the urging force of the first spring means can be used for clamping the tool.

Further, in the spindle drive device according to the second aspect, the pressure applying means uses air as a pressure medium and uses air pressure as a pressure source, or uses oil as a pressure medium and uses hydraulic pressure as a pressure source. I have to be. Therefore, a large urging force can be obtained by using air pressure or oil pressure as a pressure source, so that the piston member can be easily moved against the first spring means. Therefore, the speed of movement of the rod to the unclamping position can be increased.

Further, in the spindle driving device according to the third aspect, the time required for the rod to move to the clamp position side by the pressure applying means and the first spring means, the pressure applying means and the second
The spring force of the first spring means and the second spring means is set such that the time required for the spring means to move the rod toward the unclamping position is equal. Therefore, the moving time of the rod to the unclamping position side can be shortened as fast as the moving time to the clamp position side.

Further, in the spindle drive device according to the fourth aspect, the spindle drive device is used for a machining center having a tool changing device. Therefore,
By increasing the speed of the unclamping operation of the spindle drive device, the attachment and detachment of the tool holder by the spindle drive device of the machining center can be accelerated, so that the tool exchange speed and the workpiece machining speed of the machining center can be increased.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on an example of an embodiment shown in the drawings. In the present embodiment, the distal end T of the spindle driving device 1 means the side on which the tool holder 2 is mounted, and the proximal end B means the side opposite to the distal end T with respect to the longitudinal direction of the rod 3.

As shown in FIGS. 1 to 3, a spindle driving device 1 of the present embodiment comprises a tool 5 held on a tool holder 2 by a spindle 4 rotated by a rotational driving force of a motor (not shown). Is driven to rotate. In the present embodiment, the spindle driving device 1 is used by being incorporated in a machining head of a machining center.

The spindle driving device 1 has a clamping position (a position on the base end B as shown in FIG. 2) where the spindle 4 holds the tool holder 2 and an unclamping position (FIG. 1) where the holding of the tool holder 2 is released. , A piston member 7 that is accommodated in the pressure chamber 6 and changes the position of the rod 3 to a clamp position or an unclamping position, and a pressure medium that moves the pressure medium to the pressure chamber 6. Pressure applying means (not shown) for changing the position of the piston member 7 to the clamp position or the unclamping position by injecting the piston member 7
And a first spring means 8 for urging the rod 3 toward the clamp position, and a second spring means 9 for urging the piston member 7 toward the unclamping position.

The spindle driving device 1 includes a chuck unit 10 disposed at the most distal end side T for holding the tool holder 2, a rotation driving unit (not shown) for rotating the spindle 4, and a rod 3 A clamp operation section 11 for moving the base side B and the base end side B, and a coolant supply section (not shown) arranged at the base end side B and supplying coolant to the tool 5 via the rod 3 and the tool holder 2 And

The rotation drive unit includes a motor, and a pulley and a belt (not shown) for connecting the motor to the spindle 4.

The rod 3 communicates from the chuck section 10 to the coolant supply section. At the center of the rod 3, a coolant circulation hole 12 formed of a through-hole for allowing the coolant from the coolant supply unit to flow through the tool holder 2 is formed. The rod 3 is slidably accommodated inside a cylindrical spindle 4. The spindle 4 communicates from the chuck portion 10 to a position just before the piston member 7,
The casing 13 is rotatably supported by a bearing 14.

A first spring means 8 is fitted between the rod 3 and the spindle 4. The first spring means 8 comprises a large number of disc springs in this embodiment. As shown in FIG. 3, the distal end T of the first spring means 8 is
And is in contact with the locking step 16 on the inner periphery of the spindle 4 via the. As shown in FIGS. 1 and 2, the proximal end B of the first spring means 8 is in contact with the enlarged diameter portion 18 of the rod 3 via the collar 17. The enlarged diameter portion 18 is formed to have an outer diameter slightly smaller than the inner diameter of the spindle 4.

When no external force is exerted on the rod 3 by the piston member 7, the first spring means 8 retracts the tool holder 2. Rod 3 by piston member 7
Moves to the tip end side T, the entire length of the first spring means 8 is compressed and urged. At this time, the first spring means 8
Urges the rod 3 toward the base end B, that is, toward the clamp position. Further, the first spring means 8 has friction in the circumferential direction of the rod 3 and the spindle 4. For this reason,
The rod 3 rotates simultaneously with the rotation of the spindle 4.

Further, a sleeve 19 slidable with respect to the rod 3 and a piston member 7 slidable relative to the rod 3 and slidable are provided on the base end side B of the enlarged diameter portion 18. I have. A fixed sleeve 20 is provided around the sleeve 19. A stopper 21 is attached around the fixed sleeve 20. The stopper 21 is screwed to the end on the base end side B of the spindle 4. The fixed sleeve 20 is fixed to the spindle 4 by a stopper 21. An O-ring 22 is mounted on the inner peripheral surface of the fixed sleeve 20 to brake the sliding of the sleeve 19 in the axial direction. For this reason, if the enlarged diameter portion 18 moves to the base end side B vigorously and then stops, the sleeve 19 also stops immediately, so that
The sleeve 19 can be prevented from contacting the piston member 7.

The clamp operation section 11 includes a piston member 7 movable to a distal end side T and a proximal end side B, and a distal end side wall 24 forming a distal end side pressure chamber 23 at the distal end side T of the piston member 7.
A proximal side wall 26 forming a proximal pressure chamber 25 on the proximal side B of the piston member 7; and a distal end formed on the distal side wall 24 for communicating the distal pressure chamber 23 with the outside of the spindle driving device 1. A side communication hole 27, a base side communication hole 28 formed in the base side wall 26 and communicating the base side pressure chamber 25 with the outside of the spindle driving device 1, a front side wall 24 and a base side wall 26.
And a biasing member 29 that biases the piston member 7 toward the distal end T by receiving the biasing force of the second spring means 9.

The piston member 7 includes a cylindrical boss portion 30 provided on the outer periphery of the rod 3 and a disk-shaped piston portion 3.
And 1. There is a slight gap S3 between the boss 30 and the rod 3. Therefore, even if the rod 3 rotates, no friction occurs between the rod 3 and the piston member 7.

When the piston portion 31 moves to the distal end T, that is, the unclamping position side, the distal end T of the boss portion 30 moves through the sleeve 19 to the enlarged portion 18 of the rod 3 as shown in FIG. To move the rod 3 toward the distal end T against the reaction force of the first spring means 8. Further, when the piston portion 31 moves to the base end side B, that is, the clamp position side, as shown in FIG.
Are separated from each other to form a gap S6. For this reason, even if the spindle 4 rotates during clamping, the boss 30 that does not rotate
It is possible to prevent friction from occurring between them.

A cylinder peripheral wall 32 is attached to the outer periphery of the piston portion 31. The distal side wall 24 is disposed on the distal side T of the cylinder peripheral wall 32 and the proximal side wall 26 is disposed on the proximal side B. The base side wall 26, the cylinder peripheral wall 32, and the front end side wall 24 are
And can slide with respect to the casing 13. Further, the cylinder peripheral wall 32, the distal side wall 24, and the proximal side wall 26 form a pressure chamber 6 that accommodates the piston portion 31. O-rings 34, 34 are used at the joints between the cylinder peripheral wall 32, the distal side wall 24, and the proximal side wall 26, respectively. Is used, the pressure chamber 6 has high airtightness. Further, a seal ring 36 is mounted on the outer peripheral surface of the piston portion 31. For this reason, the pressure chamber 6 is
The airtightness is maintained in each of the pressure chambers 23 and 25.

The second spring means 9 comprises a rectangular compression coil spring wound with a wire having a rectangular cross section. Therefore, a strong spring can be provided for a small volume. However, it is needless to say that the compression spring is not limited to a rectangular compression coil spring. Here, the spring force of the second spring means 9 is the first spring means.
It is set smaller than the spring force of the spring means 8. For this reason, the second spring means 9 and the first spring means 8 are
When the piston 3 and the piston member 7, the sleeve 19 and the rod 3 are pressed against each other, the rod 3 is located at the base end B (clamp position).

The spring force of the first spring means 8 and the second spring means 9 is determined by the time required for the first spring means 8 to move the rod 3 toward the clamp position, the time required for the piston member 7 and the second
It is preferable to set the movement time of the rod 3 to the unclamping position side by the spring means 9 to be equal.
Thereby, the moving time of the rod 3 to the unclamping position side can be shortened to the same speed as the moving time to the clamp position side.

Each of the communication holes 27 and 28 is provided with a high-pressure air jet nozzle (not shown) as pressure applying means. Further, each communication hole 27 of the piston portion 31,
An annular groove 31a is formed in a portion facing 28. For this reason, when high pressure air is blown into the base end communication hole 28 when the piston portion 31 is at the base end B (clamp position), the high pressure air is blown into the groove 3 on the base end B of the piston portion 31.
Since the piston portion 31 goes around the entirety of 1a, the piston portion 31 can be easily moved to the distal end side T. At this time, the second spring means 9 moves the piston portion 31 via the urging member 29 to the tip side T.
, The moving speed of the piston portion 31 to the unclamping position can be increased. On the other hand, if high-pressure air is blown into the front-end side communication hole 27 when the piston portion 31 is at the front-end side T (unclamping position), the high-pressure air flows around the entire groove 31a on the front-end side T of the piston portion 31. 31 can be easily moved to the base end side B.

Further, a hook member 37 is fixed to the tip side T of the tip side wall 24 by a bolt 38. The hook member 37 is provided with a small gap S4 with respect to the outer periphery of the stopper 21, and is relatively slidable and rotatable with respect to the stopper 21. Here, at the engagement portion between the hook member 37 and the stopper 21, the hook member 37
Protrudes to the inner peripheral side, and the flange portion 21a of the stopper 21 protrudes to the outer peripheral side at the base end side B. Further, the flange portion 21a of the stopper 21 is accommodated in the circular concave portion of the distal end side wall 24 with a radial gap S8.

Therefore, the stopper 21 and the hook member 37
In addition, there are always gaps S4 and S8 in the radial direction with respect to the tip side wall 24 regardless of the position in the axial direction. Further, the spindle 4 and the stopper 21 are urged toward the distal end side T, and the distal end side wall 2 is
When the hook 4 and the hook member 37 are urged toward the base end side B,
The flange portion 21a of the stopper 21 and the hook member 37 abut in the axial direction, eliminating the axial gap S5, thereby restricting the relative movement.

On the other hand, at the time of clamping (shown in FIG. 2), the piston member 7, the tip side wall 24 and the hook member 37 are urged toward the tip side T by the second spring means 9, so that the flange portion of the stopper 21 is formed. A gap S5 in the axial direction is formed between the hook 21 and the hook member 37, and the stopper 21 and the tip side wall 2 are formed.
4, a gap S7 in the axial direction is generated. For this reason, since there are the gaps S4, S5, S7, and S8, it is possible to prevent contact between the rotating member and the non-rotating member even when the spindle 4 rotates.

When high-pressure air is blown into the proximal communication hole 28 when the rotation of the spindle 4 is stopped, the piston 31 is urged toward the distal end T so as to be separated from the proximal side wall 26. For this reason, the urging force to the tip side T acts on the boss portion 30, the sleeve 19, the rod 3, the first spring means 8, the spindle 4, and the stopper 21. At the same time, high-pressure air is blown into the proximal communication hole 28 so that the proximal side wall 2 is formed.
6, cylinder peripheral wall 32, tip side wall 24, and hook member 37
, A reaction force toward the base end side B acts. These biasing forces in the opposite directions are offset by the tension between the stopper 21 and the hook member 37.

On the other hand, as shown in FIG. 3, a taper shank 2 of the tool holder 2 is
a is detachable. A tool 5 is mounted on the tip side T of the tool holder 2. A through hole 39 is formed in the center of rotation of the tool holder 2 and communicates with the coolant circulation hole 12 of the rod 3. Therefore, the coolant from the coolant supply unit can be supplied to the tool 5.

A space 40 occupied by the pull stud 2b of the mounted tool holder 2 is formed immediately proximal to the tool holder 2 of the spindle 4. In addition, a communication hole 41 that communicates the space 40 with the outside of the spindle driving device 1 is formed. A high-pressure air ejection nozzle (not shown) is connected to a portion 42 where the communication hole 41 is exposed to the outside. A collet 43 for holding the pull stud 2b is attached to the base end B of the space 40 occupied by the pull stud 2b. The collet 43 is attached to the end of the rod 3 on the distal end side T. Therefore, when the rod 3 is in the clamp position, the collet 43
Is urged toward the base end B by the rod 3, so that the pull stud 2b of the mounted tool holder 2 is sandwiched and pulled toward the base end B. Thus, the tool holder 2 is pressed and held against the spindle 4.

The operation of the spindle drive 1 will be described below.

When a machining operation is performed by the tool 5 held on the chuck section 10, a motor is driven. Thereby, the spindle 4 rotates to rotate the tool holder 2 and the tool 5. At this time, the rod 3, the first spring means 8, the stopper 21, the fixed sleeve 20, and the sleeve 19 are simultaneously rotated.

Here, in order to avoid contact between the non-rotating boss portion 30 and the rotating sleeve 19, it is necessary to position the boss portion 30 on the base end side B. Therefore, high-pressure air is blown into the distal communication hole 27 to position the piston portion 31 on the proximal end B. At this time, since the piston portion 31 receives the reaction force of the second spring means 9, the pressure of the high-pressure air is made slightly higher than that of the second spring means 9.

Further, since the sleeve 19 is braked by the O-ring 22 in the movement in the axial direction, the sleeve 19 does not move in the axial direction during rotation. Thereby, the collision between the sleeve 19 and the boss portion 30 can be prevented. Further, when the tool 5 rotates, the coolant is ejected from the coolant supply unit, and the coolant flow holes 12
And through the through hole 39 of the tool holder 2 to be supplied to the tool 5. Thereby, the tool 5 can be cooled and the friction at the time of machining can be reduced.

When the tool holder 2 is replaced, the rotation of the tool 5 is stopped, and then the supply of high-pressure air to the distal end side communication hole 27 is stopped. Thereby, the second spring means 9
Pushes the piston portion 31 toward the distal end side T via the urging member 29 to move it. For this reason, while the high pressure air blown into the base end side pressure chamber 25 next can be drawn in,
The boss portion 30 can close the gap S6 and press the sleeve 19 and the enlarged diameter portion 18.

On the other hand, the supply of high-pressure air to the distal communication hole 27 is stopped, and at the same time, the supply is switched to supply high-pressure air to the proximal communication hole 28. Here, a time lag occurs due to an initial response delay when switching the supply target of the high-pressure air.
Is moved to the distal end T, so that the rising time can be reduced without wasting time, and the speed of movement of the rod 3 toward the distal end T can be increased. When the rod 3 is moved to the unclamping position on the tip side T, the rod 3 is moved by the combined force of the air pressure acting on the piston member 7 and the urging force of the second spring means 9. For this reason, the unclamping force can be increased as compared with the conventional case in which the rod 3 is moved only by the air pressure acting on the piston member 7, so that the speed of movement of the rod 3 toward the distal end side T can be increased. For this reason, the unclamping operation of the tool holder 2 in the spindle drive device 1 can be accelerated, and the tool exchange in the machining center can be accelerated, so that the efficiency of work processing can be improved.

Then, the piston member 7 moves the sleeve 19 and the rod 3 to the tip side T while opposing the reaction force of the first spring means 8. Here, the tip side T of the first spring means 8
Of the spindle 4 via the collar 15
6, the spindle 4 and the stopper 21
Then, a pressing force to the tip side T acts. On the other hand, the base wall 26, the cylinder peripheral wall 32, the tip side wall 24, and the hook member 37 receive the reaction force toward the base side B generated in the base side pressure chamber 25, and Power is occurring. For this reason,
The reaction force generated between the piston member 7 and the spindle 4 becomes a tensile stress between the stopper 21 and the hook member 37. Therefore, no load is applied to the bearing 14 supporting the spindle 4 in the axial direction.

On the other hand, since the collet 43 is pushed out to the distal end T at the distal end T of the rod 3, the tool holder 2
Pull stud 2b is released. Thereby, the tool holder 2 can be removed. At this time, high-pressure air is ejected from a high-pressure air ejection nozzle connected to the opening 42 connected to the space 40 occupied by the pull stud 2b, and is blown into the space 40. Thereby, air is blown out from the periphery of the tapered shank 2a to remove dust.

Then, after exchanging the tool holder 2 with the tool holder 2 for holding the tool 5 used for the next machining,
High pressure air is blown into the distal end side communication hole 27 of the distal side wall 24. As a result, the piston member 7 is moved to the proximal side B and the first spring means 8 is released, so that the rod 3 moves to the proximal side B. Therefore, the collet 43 moves to the base end side B, the pull stud 2b of the tool holder 2 is chucked, and the tool holder 2 is held. At the same time, rod 3
Moves the sleeve 19 to the proximal side B.

Further, the piston member 7 is moved to make contact with the base end wall 26. Here, since the reaction force of the second spring means 9 is acting on the piston portion 31, air pressure capable of obtaining a slightly larger urging force is supplied to the front-end side pressure chamber 23. At this time, since the boss portion 30 and the sleeve 19 are separated from each other to form a gap S6, friction does not occur between these members when the motor is driven and the spindle 4 rotates, and heat generation and the like are considered. No need. Therefore, high-speed rotation can be easily performed.

Moreover, at the time of clamping, the first spring means 8
Since the second spring means 9 and the second spring means 9 do not press against each other, all the urging force of the first spring means 8 can be used for chucking the tool holder 2. When clamping, the second
Since the piston member 7, the tip side wall 24, and the hook member 37 are urged toward the tip side T by the spring means 9, the axial gap S5 between the hook member 37 and the stopper 21 can be reliably ensured.

The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, although air is used as the pressure medium in the present embodiment, the present invention is not limited to this, and oil or another medium may be used. Also in this case, even if a time lag occurs when the supply of the high-pressure medium is switched from the distal communication hole 27 to the proximal communication hole 28, the second spring means 9 moves the piston member 7 to the distal side T during that time. Therefore, the speed of movement of the rod 3 can be increased.

[0056]

As is apparent from the above description, according to the spindle driving device of the first aspect, the rod which moves the spindle to the clamp position for holding the tool and the unclamping position for releasing the tool, and the pressure, A piston member housed in the chamber and changing the position of the rod to a clamp position or an unclamping position, and pressure applying means for injecting a pressure medium into the pressure chamber and changing the position of the piston member to the clamp position or the unclamping position; The first spring means for urging the rod toward the clamp position, and the second spring means for urging the piston member toward the unclamped position. The rod can be changed to the unclamping position by the combined force with the urging force of the two spring means. For this reason, the unclamping force can be increased as compared with the related art, and the movement of the rod to the unclamping position can be accelerated.

Further, when the pressure medium is switched to move the piston member to the unclamping position, the piston member is moved by the second spring means during a time lag due to an initial response delay in switching the pressure medium. Can be. Therefore, the rising time of the movement of the rod to the unclamping position can be shortened and the speed can be increased.

Therefore, the speed of the unclamping operation of the spindle drive device can be increased, and the speed of tool change can be increased.

Further, when the rod is at the clamp position, there is a gap between the rod and the piston member.
There is no interference between the spring means and the second spring means. Therefore, all the urging force of the first spring means can be used for clamping the tool.

In the spindle drive device according to the second aspect, the pressure applying means uses air as a pressure medium and uses air pressure as a pressure source, or uses oil as a pressure medium and uses hydraulic pressure as a pressure source. Because of this, a large urging force can be obtained using air pressure or oil pressure as a pressure source. Therefore, the piston member can be easily moved against the first spring means, and the movement of the rod to the unclamping position can be accelerated.

Further, in the spindle drive device according to the third aspect, the time required for the rod to move to the clamp position by the pressure applying means and the first spring means, and the pressure applying means and the second
Since the spring force of the first spring means and the second spring means is set so that the movement time of the rod to the unclamping position side by the spring means is equal, the movement of the rod to the unclamping position side is performed. The time can be reduced to the same speed as the movement time to the clamp position.

In the spindle drive device according to the fourth aspect, the spindle drive device is used for a machining center provided with a tool changing device. Therefore, the unclamping operation of the spindle drive device is accelerated to thereby increase the speed of the machining center. The attachment / detachment of the tool holder by the spindle drive device can be speeded up. For this reason, the tool exchange speed and the workpiece machining speed of the machining center can be increased.

[Brief description of the drawings]

FIG. 1 is a side view showing a main part when a spindle drive device of the present invention is in an unclamped state.

FIG. 2 is a side view showing a main part when the spindle driving device is in a clamped state.

FIG. 3 is a side view showing the chuck portion when the spindle driving device is in a clamped state.

FIG. 4 is a side view showing a conventional spindle driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spindle drive 3 Rod 4 Spindle 5 Tool 6 Pressure chamber 7 Piston member 8 First spring means 9 Second spring means

Claims (4)

[Claims] 1. A spindle drive device in which a tool is rotationally driven by a spindle rotated by a rotational driving force of a motor, wherein the spindle holds a tool and a clamp position for releasing the tool. A piston member housed in a pressure chamber and changing the position of the rod to the clamp position or the unclamping position, and injecting a pressure medium into the pressure chamber to change the position of the piston member. Pressure applying means for changing to a clamp position or unclamping position, first spring means for urging the rod toward the clamp position, and second spring means for urging the piston member toward the unclamping position. A spindle drive device comprising: 2. The spindle according to claim 1, wherein the pressure applying means uses air as the pressure medium and uses air pressure as a pressure source, or uses oil as the pressure medium and uses hydraulic pressure as a pressure source. Drive. 3. A moving time of the rod to the clamp position side by the pressure applying means and the first spring means, and a movement time of the rod to the unclamping position side by the pressure applying means and the second spring means. 3. The spindle driving device according to claim 1, wherein the spring force of the first spring means and the spring force of the second spring means are set to be equal to a moving time. 4. The spindle drive device according to claim 1, wherein the spindle drive device is used for a machining center having a tool changing device.