JP2010162647A - Rotary shaft apparatus and tool holding condition determining method in rotary shaft apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary shaft apparatus capable of accurately determining whether a tool is normally held with respect to a main spindle, and also to provide a method for determining the holding condition of the tool in the rotary shaft apparatus. <P>SOLUTION: A rod 15 removable in an axial direction is formed in the main spindle 12 of the rotary shaft apparatus 1. The rod 15 is energized backward to the main spindle 12 by a plate spring 16. The rod 15 grips a tool T at its front end, retreats in the main spindle 12, and holds the tool T at the front end of the main spindle 12. A tapered surface 152a is formed at the rear end of the rod 15, and a displacement sensor 181 is arranged oppositely to the tapered surface 152a. An abnormality determining apparatus 18 including the displacement sensor 181 calculates an acceleration when the rod 15 retreats, based on a distance with the tapered surface 152a, detected by the displacement sensor 181, and determines that the tool T is not normally held by the main spindle 12 in the case where the maximum value of the acceleration does not exceed a predetermined value. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a rotary shaft device for machining a workpiece with a tool attached to a main shaft, and a tool holding state determination method in the rotary shaft device.

  There has been a related art relating to a rotary shaft device in which a disc-shaped dog is attached to the rear end of a rod that can move in the axial direction in the main shaft, and the return position of the dog is detected by a displacement sensor (see, for example, Patent Document 1) ). This determines whether or not the rod member normally clamps the tool by detecting the return position of the rod member to which the dog is attached.

  Usually, in a rotary shaft device that processes a workpiece with a tool attached to a main shaft, the tool is held by a collet provided at the tip of a rod member that moves in the main shaft. The rod member is urged backward in the main shaft by a plurality of disc springs. After the collet grips the tool, the rod member moves backward with respect to the main shaft, and the tool is firmly pressed by the taper at the tip of the main shaft. Is retained. Therefore, in the normal case, as described above, it is possible to determine whether the tool is normally held with respect to the main shaft by detecting the return position of the rod member.

JP-A-5-50359

  Here, it is assumed that a problem occurs in the disc spring that biases the rod member, and a sufficient biasing force cannot be applied to the rod member. Even if the biasing force of the disc spring to the rod member decreases, the rod member can return to the retracted position normally if the piston that has pressed the rod member forward moves backward. Therefore, as described above, only the method of detecting the return position of the rod member could not detect the abnormality of the disc spring.

If the disc spring becomes abnormal and the load that urges the rod member backward decreases, the tool at the tip of the spindle cannot be pressed with sufficient load on the taper, and the tool swings as the spindle rotates. Has occurred, and the machining accuracy of the workpiece has been reduced.
The present invention has been made in view of the above circumstances, and an object of the present invention is to accurately determine whether or not the tool is normally held with respect to the main shaft and a method for determining the holding state of the tool in the rotary shaft device. Is to provide.

In order to solve the above-described problem, the structural features of the invention of the rotary shaft device according to claim 1 are as follows:
A housing extending in a cylindrical shape in the axial direction by having an accommodation space on the inner periphery,
A main shaft that is rotatably mounted to the housing via a bearing by being disposed in the housing space;
A rod member provided in the main shaft so as to be movable in the axial direction;
Biasing means for biasing the rod member backward with respect to the main shaft;
Rod moving means for moving the rod member forward;
With
The rod member engages with a tool at a front end, is urged by the urging means, retreats within the main shaft, and holds the tool at a tip portion of the main shaft,
In the rotary shaft device in which the rod member is moved forward by the rod moving means to be disengaged from the tool.
Tool holding state determining means for determining whether or not the tool is normally held on the main shaft based on the acceleration when the rod member is retracted is provided.

The structural feature of the invention according to claim 2 is the rotating shaft device according to claim 1,
A taper surface inclined in the axial direction is formed at the rear of the rod member,
The tool holding state determination means includes
A displacement sensor that faces the taper surface in a radial direction and detects a distance from the taper surface;
Based on the distance from the tapered surface detected by the displacement sensor, the acceleration when the rod member is retracted is detected.

The structural feature of the invention according to claim 3 is the rotating shaft device according to claim 1 or 2,
The tool holding state determination means includes
When the maximum acceleration value when the rod member is retracted does not exceed a predetermined value, it is determined that the tool is not normally held on the spindle.

A structural feature of the invention according to claim 4 is the rotating shaft device according to any one of claims 1 to 3,
The tool holding state determination means includes
When the rod member does not retract within a predetermined time, it is determined that the tool is not normally held on the spindle.

The structural feature of the invention according to claim 5 is the rotating shaft device according to claim 1 or 2,
The tool holding state determination means includes
When the maximum acceleration value when the rod member is retracted does not exceed a predetermined value,
Or, when the rod member does not retract within a predetermined time,
Alternatively, when the rod member does not return to the rear original position, it is determined that the tool is not normally held on the spindle.

The structural features of the invention of the method for determining the holding state of the tool in the rotary shaft device according to claim 6 are as follows:
A housing extending in a cylindrical shape in the axial direction by having an accommodation space on the inner periphery,
A main shaft that is rotatably mounted to the housing via a bearing by being disposed in the housing space;
A rod member provided in the main shaft so as to be movable in the axial direction;
Biasing means for biasing the rod member backward with respect to the main shaft;
Rod moving means for moving the rod member forward;
With
The rod member engages with a tool at a front end, is urged by the urging means, retreats within the main shaft, and holds the tool at a tip portion of the main shaft,
In the method for determining the holding state of the tool in the rotary shaft device in which the rod member is moved forward by the rod moving means, and the engagement with the tool is released.
It is to determine whether or not the tool is normally held on the spindle based on the acceleration when the rod member is retracted.

  According to the rotary shaft device of the first aspect, the rod member is urged backward by the urging means by determining whether or not the tool is normally held by the main shaft based on the acceleration when the rod member is retracted. When the urging force to be reduced or when the rod member is caught on the main shaft or the like, the acceleration when the rod member is retracted decreases, so that the abnormality can be detected.

  According to the rotary shaft device of the second aspect, the taper surface is formed on the rod member, and the acceleration when the rod member is retracted is detected based on the distance from the taper surface detected by the displacement sensor. Thus, the acceleration of the rod member can be detected using a single displacement sensor over the entire stroke of the rod member. In addition, since it is not necessary to use a large number of displacement sensors, the displacement sensor can be easily assembled to the rotary shaft device, and the detection area of the displacement sensor can be reduced.

  According to the rotary shaft device of the third aspect, when the maximum value of the acceleration when the rod member is retracted does not exceed the predetermined value, it is determined that the tool is not normally held on the main shaft. It is possible to accurately detect a decrease in the urging force that urges the rearward.

According to the rotating shaft device of the fourth aspect, when the rod member does not retract within a predetermined time, the biasing force that biases the rod member backward by determining that the tool is not normally held by the main shaft. Can be easily detected.
In addition to determining whether or not the tool is normally held on the spindle based on the acceleration when the rod member is retracted, it is possible to double determine whether or not the tool is held correctly, improving the accuracy of the determination. Can be made.

  According to the rotary shaft device of the fifth aspect, when the maximum value of the acceleration when the rod member moves backward does not exceed the predetermined value, or when the rod member does not move backward within the predetermined time, or the rod member moves backward. If the tool is not returned to the original position, it is possible to reduce erroneous detection of an abnormal holding of the tool by determining that the tool is not normally held on the spindle.

  According to the method for determining the holding state of the tool in the rotary shaft device according to claim 6, the rod member is moved backward by determining whether or not the tool is normally held by the main shaft based on the acceleration when the rod member is retracted. When the urging force for urging is reduced, the acceleration when the rod member is retracted is reduced, so that the abnormality can be detected.

1 is an axial sectional view of a rotary shaft device according to an embodiment of the present invention. Axial sectional view of the rotary shaft device when the tool is not gripped Enlarged view showing the relationship between the taper surface and the displacement sensor when the rod is holding the tool Enlarged view showing the relationship between the taper surface and displacement sensor when the rod is moving forward A graph showing the relationship between acceleration and elapsed time when the rod is retracted

  Based on FIG. 1 thru | or FIG. 5, the rotating shaft apparatus 1 by one Embodiment of this invention is demonstrated. In FIG. 1, the left-right direction is the rotational axis direction or the axial direction, and the left side is the front. In FIG. 2, the amplifier 182, the differentiator 183, and the controller 184 that constitute the abnormality determination device 18 are omitted. As shown in FIG. 1, the rotary shaft device 1 according to the present embodiment includes a rotary shaft housing 11 (corresponding to a housing of the present invention) and a main shaft 12 provided inside the rotary shaft housing 11. The rotating shaft housing 11 has an accommodating space 111 on the inner periphery, and has a substantially cylindrical shape extending in the rotating shaft direction.

  Two pairs of bearings 131 and 132 are fixed in the axial direction in front of the housing space 111 of the rotary shaft housing 11. Further, one bearing 133 is formed in the rear of the accommodation space 111 (these bearings 131 to 133 are collectively referred to as the bearing 13). The outer peripheral surface of the main shaft 12 is press-fitted into the inner peripheral portion of the bearing 13, whereby the main shaft 12 is attached to the rotary shaft housing 11 so as to be rotatable and immovable in the axial direction.

  A stator 141 of the electric motor 14 is attached to the inner peripheral surface of the rotary shaft housing 11. A rotor 142 formed on the outer peripheral surface of the main shaft 12 is opposed to the inner side of the stator 141 in the radial direction. By supplying electric power to the electric motor 14 formed by the stator 141 and the rotor 142, the main shaft 12 rotates together with the rotor 142. The rotary shaft device 1 rotates the main shaft 12 with the tool T attached to the tip, and processes a workpiece (not shown).

  A rod hole 121 extending in the axial direction is formed at the center of the rotation axis of the main shaft 12. The rod hole 121 penetrates the main shaft 12 in the rotation axis direction, and a tool attaching taper portion 121a is formed at the front end. A collet housing part 121b is formed behind the tool mounting taper part 121a, and a spring housing hole 121c having a diameter larger than that of the collet housing part 121b is provided further behind the collet housing part 121b. A sleeve member 122 is fixed to the front end portion of the spring accommodating hole 121c.

  A rod 15 (corresponding to the rod member of the present invention) is accommodated in the rod hole 121 so as to be movable in the axial direction. The rod 15 is formed by fixing a stopper 152 having a diameter larger than that of the shaft member 151 to the rear end portion of the long shaft member 151. Further, a collet 153 is formed at the front end of the rod 15. The collet 153 is provided so as to be able to expand and contract in the radial direction, and is formed so that the tool T can be gripped.

  In a state in which the rod 15 is accommodated in the rod hole 121, the shaft member 151 of the rod 15 is slidable with the inner peripheral surface of the sleeve member 122, and the stopper 152 is slidable with the spring accommodating hole 121c. Has been. A plurality of disc springs 16 (corresponding to the biasing means of the present invention) are interposed between the rear end portion of the sleeve member 122 and the front end surface of the stopper 152 of the rod 15. Thereby, the rod 15 is always urged backward with respect to the main shaft 12.

  The rotary shaft device 1 is provided with a hydraulic cylinder 17 (corresponding to the rod moving means of the present invention) so as to be positioned behind the main shaft 12. The hydraulic cylinder 17 includes a cylinder housing 171 integrated with the rotary shaft housing 11 and a piston 172 provided in the cylinder housing 171 so as to be movable in the axial direction. The piston 172 is liquid-tightly accommodated in the cylinder housing 171, and a pair of hydraulic chambers 173 a and 173 b are formed between the cylinder housing 171 and the piston 172.

  The front hydraulic pressure chamber 173a is formed in front of the outer peripheral projection 172a of the piston 172, and moves the piston 172 rearward when hydraulic pressure is introduced. On the other hand, the rear hydraulic chamber 173b is formed behind the outer peripheral projection 172a, and the piston 172 can be moved forward by introducing hydraulic pressure.

When the piston 172 is moved rearward, the engagement between the piston 172 and the rod 15 is released, and the rod 15 moves rearward with respect to the main shaft 12 by the biasing force of the disc spring 16. When the rod 15 holding the tool T is retracted, the tool T is pressed by the tool mounting tapered portion 121a of the spindle 12 and fixed to the spindle 12 (shown in FIG. 1). FIG. 1 shows a state in which the rod 15 is in the rear original position.
When the piston 172 moves forward, the rod 15 moves forward against the urging force of the disc spring 16 by engaging with the piston 172. When the rod 15 moves forward, the collet 153 expands to release the tool T (shown in FIG. 2).

  A piston position detecting device 174 formed by a pair of proximity switches is attached to the cylinder housing 171. The piston position detection device 174 detects the position of the piston 172 by operating each proximity switch when the detection unit 175 protruding in the radial direction of the piston 172 approaches or separates.

As shown in FIG. 3, a tapered surface 152 a inclined in the axial direction is formed at the rear end portion of the stopper 152 of the rod 15. Therefore, the outer peripheral surface of the stopper 152 is formed with a smaller diameter as it goes rearward.
A displacement sensor 181 constituting an abnormality determination device 18 (corresponding to the tool holding state determination means of the present invention) is attached to the rear end portion of the rotary shaft housing 11. The displacement sensor 181 is attached by a bracket 112 connected to the rotary shaft housing 11 so as to face the tapered surface 152a in the radial direction. The displacement sensor 181 is a non-contact sensor with respect to the stopper 152. For example, an eddy current sensor or the like is used to detect the distance from the tapered surface 152a.

  As shown in FIG. 3, when the stopper 152 is retracted, the distance from the tapered surface 152a is detected by the displacement sensor 181 as d. As shown in FIG. 4, when the stopper 152 moves forward, the distance between the displacement sensor 181 and the tapered surface 152a is increased, and the distance is detected as D (D> d). Accordingly, the axial position of the rod 15 is detected based on the distance from the tapered surface 152a detected by the displacement sensor 181. As a result, the axial movement stroke of the rod 15 is detected based on the axial position. be able to.

  A detection signal from the displacement sensor 181 is amplified by the amplifier 182 shown in FIG. 1 and then transmitted to the differentiator 183. In the differentiator 183, the amplified detection signal is second-order differentiated to calculate the acceleration α when the rod 15 moves backward. The controller 184 receives the acceleration α of the rod 15 from the differentiator 183 and determines whether the tool T is normally held on the spindle 12 based on the acceleration α when the rod 15 is retracted. The amplifier 182, the differentiator 183, and the controller 184 constitute an abnormality determination device 18 together with the displacement sensor 181.

After the collet 153 grips the tool T, when the piston 172 is retracted and the engagement with the stopper 152 is released, the rod 15 starts to retract due to the biasing force of the disc spring 16, and the acceleration α toward the rear of the rod 15 is increased. To rise. When the rod 15 and the disc spring 16 are functioning normally and the rod 15 is normally retracted, the acceleration α of the rod 15 rapidly increases, and its maximum value α ₁ exceeds a predetermined value α ₀ (see FIG. 5 is indicated by a solid line).

On the other hand, when there is an abnormality in the disc spring 16 and the urging force is not sufficient, or when the rod 15 is caught by the main shaft 12 and the rod 15 does not return to agility, the acceleration α to the rear of the rod 15 The rise of is slow. In this case, the maximum value α ₂ of the acceleration α of the rod 15 does not exceed the predetermined value α ₀ described above (indicated by a broken line in FIG. 5).

When the maximum value α ₂ of the acceleration α of the rod 15 does not exceed the predetermined value α ₀ , the controller 184 determines that there is an abnormality in the rod 15 or the disc spring 16 and the tool T is not normally held on the spindle 12. To do. When the controller 184 determines that the tool T is not normally held on the spindle 12, it sends an abnormality signal and turns on a warning lamp to notify the operator of the occurrence of the abnormality, or the spindle 12 is rotating. If there is, the rotation is stopped or the gripping state of the tool T by the collet 153 is detected.

Further, when the rod 15 and the disc spring 16 are functioning normally and the rod 15 is normally retracted, an elapsed time T from when the engagement with the piston 172 is released until the rod 15 completes the retracting. ₁ does not exceed the predetermined time T ₀ (indicated by a solid line in FIG. 5).
However, when the rod 15 or the disc spring 16 has an abnormality and the rod 15 does not return to normal, the elapsed time T ₂ from when the engagement with the piston 172 is released until the rod 15 completes retraction is predetermined. Time T ₀ will be exceeded (indicated by a broken line in FIG. 5).
The controller 184 determines that the tool T is not normally held on the spindle 12 when the elapsed time T ₂ until the rod 15 completes retraction exceeds a predetermined time T ₀ , and transmits an abnormal signal.
Furthermore, when the controller 184 detects that the rod 15 does not return to the original position (shown in FIG. 1) even if the rod 15 starts to move backward, the tool T is not normally held on the spindle 12. Is determined and an abnormal signal is transmitted.

  In the present embodiment, the biasing force that biases the rod 15 backward by the disc spring 16 is determined by determining whether or not the tool T is normally held on the main shaft 12 based on the acceleration when the rod 15 is retracted. When the rod 15 is lowered or when the rod 15 is caught on the main shaft 12 or the like, the acceleration when the rod 15 moves backward is lowered, so that the abnormality can be detected.

  Further, a taper surface 152a is formed on the rod 15, and based on the distance from the taper surface 152a detected by the displacement sensor 181, the acceleration when the rod 15 moves backward is detected. Thereby, the acceleration of the rod 15 can be detected using the single displacement sensor 181 irrespective of the movement stroke of the rod 15. In addition, since it is not necessary to use a large number of displacement sensors 181, the displacement sensor 181 can be easily assembled to the rotary shaft device 1, and the detection area of the displacement sensor 181 can be reduced.

Further, when the maximum acceleration value when the rod 15 is retracted does not exceed a predetermined value, it is determined that the tool T is not normally held by the main shaft 12, thereby biasing the rod 15 backward. Can be accurately detected.
Further, when the rod 15 does not retreat within a predetermined time, it is easily detected that the tool T is not normally held by the main shaft 12 to reduce the urging force that urges the rod 15 backward. be able to.

Further, in addition to determining whether or not the tool T is normally held on the spindle 12 based on the acceleration when the rod 15 is retracted, the holding failure of the tool T can be determined in a double manner. Accuracy can be improved.
Further, when the maximum value of acceleration when the rod 15 is retracted does not exceed a predetermined value, or when the rod 15 does not retract within a predetermined time, or when the rod 15 does not return to the rear original position, By determining that T is not normally held on the spindle 12, it is possible to reduce erroneous detection of abnormal holding of the tool T.

<Other embodiments>
The present invention is not limited to the above-described embodiments, and can be modified or expanded as follows.
The controller 184 determines only the maximum acceleration value when the rod 15 is retracted without determining the retreat time of the rod 15 and the return of the rod 15 to the original position behind the rod 15, and when this does not exceed a predetermined value. It may be determined that the tool T is not normally held on the spindle 12.

Further, the controller 184 does not determine the return of the rod 15 to the original position behind it, and if the maximum value of acceleration when the rod 15 moves backward does not exceed a predetermined value, or the rod 15 moves backward within a predetermined time. If not, it may be determined that the tool T is not normally held on the spindle 12.
Further, the controller 184 determines that the maximum value of acceleration when the rod 15 is retracted does not exceed a predetermined value, or the rod 15 does not retract within a predetermined time, or the rod 15 does not return to the original position in the rear. In addition, it may be determined that the tool T is not normally held on the spindle 12.

The rod moving means for moving the rod 15 forward is not limited to the hydraulic cylinder 17 and may be an actuator using a pneumatic cylinder or an electric motor.
The displacement sensor 181 does not necessarily need to be a non-contact sensor using eddy current, and any type of optical sensor, magnetostrictive sensor, or the like can be applied. Further, any sensor that can detect the displacement of the rod 15 may be a sensor that contacts the rod 15.

  In the drawings, 1 is a rotating shaft device, 11 is a rotating shaft housing (housing), 12 is a main shaft, 13 is a bearing, 15 is a rod (rod member), 16 is a disc spring (biasing means), and 17 is a hydraulic cylinder (rod). (Moving means), 18 is an abnormality determining device (tool holding state determining means), 111 is an accommodating space, 152a is a tapered surface, 181 is a displacement sensor, and T is a tool.

Claims (6)

A housing extending in a cylindrical shape in the axial direction by having an accommodation space on the inner periphery,
A main shaft that is rotatably mounted to the housing via a bearing by being disposed in the housing space;
A rod member provided in the main shaft so as to be movable in the axial direction;
Biasing means for biasing the rod member backward with respect to the main shaft;
Rod moving means for moving the rod member forward;
With
The rod member engages with a tool at a front end, is urged by the urging means, retreats within the main shaft, and holds the tool at a tip portion of the main shaft,
In the rotary shaft device in which the rod member is moved forward by the rod moving means to be disengaged from the tool.
A rotary shaft device comprising tool holding state determination means for determining whether or not the tool is normally held on the main shaft based on acceleration when the rod member is retracted. A taper surface inclined in the axial direction is formed at the rear of the rod member,
The tool holding state determination means includes
A displacement sensor that faces the taper surface in a radial direction and detects a distance from the taper surface;
2. The rotating shaft device according to claim 1, wherein an acceleration when the rod member is retracted is detected based on a distance from the tapered surface detected by the displacement sensor. The tool holding state determination means includes
3. The rotation according to claim 1, wherein when the maximum value of acceleration when the rod member is retracted does not exceed a predetermined value, it is determined that the tool is not normally held on the main shaft. Axle device. The tool holding state determination means includes
4. The rotary shaft device according to claim 1, wherein when the rod member does not retract within a predetermined time, it is determined that the tool is not normally held by the main shaft. The tool holding state determination means includes
When the maximum acceleration value when the rod member is retracted does not exceed a predetermined value,
Or, when the rod member does not retract within a predetermined time,
Alternatively, when the rod member does not return to the rear original position, it is determined that the tool is not normally held by the main shaft. A housing extending in a cylindrical shape in the axial direction by having an accommodation space on the inner periphery,
A main shaft that is rotatably mounted to the housing via a bearing by being disposed in the housing space;
A rod member provided in the main shaft so as to be movable in the axial direction;
Biasing means for biasing the rod member backward with respect to the main shaft;
Rod moving means for moving the rod member forward;
With
The rod member engages with a tool at a front end, is urged by the urging means, retreats within the main shaft, and holds the tool at a tip portion of the main shaft,
In the method for determining the holding state of the tool in the rotary shaft device in which the rod member is moved forward by the rod moving means, and the engagement with the tool is released.
A method for determining a holding state of a tool in a rotary shaft device, wherein whether or not the tool is normally held on the main shaft is determined based on an acceleration when the rod member is retracted.

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