JP2003103459A - Spindle head structure for grinding wheel spindle having balance correcting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding wheel spindle head structure suppressing rigidity deterioration and grinding accuracy deterioration due to an increase of an axial clearance between a bearing and a grinding wheel in a grinding wheel spindle head of a grinding device having an annular automatic balance correcting device corresponding to high rotation speed. SOLUTION: In the spindle head structure, an automatic balance correcting device rotating part having a correction weight in an interior, rotating synchronously with the grinding wheel spindle and comprising an annular shape is arranged in a tip of the spindle head, and an automatic balance correcting device fixing part controlling rotary movement so as to correct unbalance to the correction weight of the automatic balance correcting device rotating part is normally arranged in an inner side face of a grinding wheel cover preventing scattering of coolant, chips, mist or the like for safety of a grinding wheel periphery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft head structure of a grindstone shaft of a grinding machine having a grindstone rotating at a high speed and an automatic balance correcting device for correcting an imbalance between the grindstone shaft.

[0002]

2. Description of the Related Art A conventional automatic balance correcting device for a rotating body such as a main shaft has a structure in which a balance weight for correcting an unbalance and a moving means such as a motor for moving the balance weight are internally provided. . This device rotates together with the rotating body, and controls the phase of two built-in counterweights so as to balance with the unbalance of the rotating body, thereby controlling the unbalance of the rotating body and the vibration of the balanced rotating body. To prevent the occurrence of. However, in a device having such a structure, when the rotating body is at a high speed, a large centrifugal force is generated due to imbalance, resulting in deformation of parts, resulting in malfunction and further destruction of parts. There is a fear. Therefore, it is necessary to set a relatively strict safety limit on the number of revolutions, which is inconvenient to apply to a rotating shaft or a rotating body that rotates at a high speed.

On the other hand, a balance correction device compatible with high-speed rotation is divided into a rotating part and a fixed part as described in, for example, US Pat. Two correction weights each having an unbalanced load portion are moved by an electromagnetic force generated by energizing a coil provided in the fixed portion. With such a structure, the rotating part of the automatic balance correction device that rotates at high speed integrally with the rotating shaft is simplified as much as possible, and it is robust and durable against unbalanced centrifugal force generated by high speed rotation. It has a structure.

In a grinder wheel spindle having an automatic balance correction device compatible with high-speed rotation as described in the above-mentioned patent publication, as shown in FIG. 4, a rotary unit 2 incorporating an automatic balance correction weight is used as a grinding wheel. A shaft head structure is provided in which the fixed portion 3 installed at the right end of 31 and having a coil built therein is fixed to the grindstone base 20 through a uniform air gap on the outer periphery of the rotating portion 2. Generally, in a rotating body such as a grindstone shaft of a grinder, it is necessary to replace the grinding wheel with a certain frequency. At that time, an imbalance occurs due to the fitting accuracy of the inner circumference of the grinding wheel 31 and the cylindrical boss 26 of the grinding wheel shaft 21. Likely to happen. Therefore, the automatic balance correction device is provided near the grinding wheel 31 where the unbalance is concentrated. Further, when exchanging the grinding wheel 31, it is desired that each time the grinding wheel 31 can be easily replaced without detaching and attaching the automatic balance correction device. Therefore, it is arranged at the right end of the grinding wheel 31 in the axial direction, that is, between the grinding wheel and the bearing. It is common to have a shaft head structure.

[0005]

However, in the case of the spindle head structure of the grindstone shaft having the above-mentioned automatic balance correction device, the axial direction of the bearing serving as the support point of the grindstone rotating shaft and the grindstone wheel in which the grinding process is performed. The separation distance is increased by the width of the balancer rotating portion, and the moment obtained by multiplying the separation distance and the centrifugal force due to wheel unbalance increases, causing a problem of whirling of the tip of the grinding wheel.
In addition, as the axial separation distance increases, the moment increases with respect to the grinding resistance force that acts on the grindstone during grinding, so the rigidity at the grindstone tip, which is the grinding point, decreases, and a sufficiently machined surface is created. There is a problem that cannot be obtained.

From the above, in the case of the shaft head structure as in the prior art, although the whirling and vibration generated by the imbalance are reduced by using the automatic balance correcting device, the rigidity of the grindstone shaft is lowered. Then, there is a problem that a sufficient processing result cannot be obtained.

Therefore, the present invention suppresses a decrease in rigidity and a decrease in grinding accuracy due to an increase in the axial separation distance between the bearing and the grinding wheel in the grinding wheel shaft head of a grinding device having an annular automatic balance correction device for high-speed rotation. The purpose is to realize a grindstone shaft head structure.

[0008]

In order to achieve the above-mentioned object, the present invention provides a grinding wheel spindle head of a grinding machine having an annular automatic balance correction device capable of high-speed rotation, as set forth in claim 1. An automatic balance correction device with an internal correction weight and an annular shape that rotates in synchronization with the grindstone shaft is placed at the shaft head to correct the unbalance of the correction weight of the automatic balance correction device rotation unit. In addition, the automatic balance correcting device fixing portion for controlling the rotational movement is formed on the inner surface of the whetstone cover to form the shaft head structure of the grindstone shaft having the balance correcting device.

Next, according to a second aspect of the present invention, in the spindle head structure of the grindstone shaft having the balance correcting device according to the first aspect, the automatic balance correcting device rotating portion is provided on the whetstone fixing cap. It is characterized in that it is fitted to the outer periphery to be integrated.

Next, according to a third aspect of the present invention, in the shaft head structure of the grindstone shaft having the balance correcting device according to the first aspect, the automatic balance correcting device fixing portion is arranged. It is characterized in that the grindstone cover positions the automatic balance correction device fixing portion with respect to the automatic balance correction device rotating portion and allows the automatic balance correction device fixing portion to be opened and closed.

[0011]

According to the invention of claim 1, based on the above-mentioned structure, the automatic balance correction device rotating part having an annular shape is arranged on the shaft head of the grindstone, and the fixing part is arranged on the inner surface of the grindstone cover. By doing so, it is possible to shorten the axial separation distance between the bearing that serves as the support point of the grindstone rotating shaft and the grindstone on which the grinding process is performed, compared to the shaft head structure of the prior art. Since the moment generated by multiplying the centrifugal force can be reduced, whirling of the tip of the grindstone can be suppressed. In addition, the fact that the axial separation distance can be shortened also reduces the moment against the grinding resistance force that acts on the grindstone during grinding, so the rigidity at the grindstone tip that is the grinding point can be secured and a sufficient machined surface can be obtained. be able to. That is, whirling and vibration caused by imbalance can be reduced by the automatic balance correction device while maintaining the rigidity of the grindstone shaft when the automatic balance correction device is not provided, and the effect can be sufficiently exhibited.

According to the second aspect of the present invention, the rotating portion of the automatic balance correction device is fitted to and integrated with the outer periphery of the whetstone fixing cap, so that when the whetstone is replaced, the conventional whetstone fixing cap is used. Similar workability can be secured.

According to the third aspect of the present invention, by making the grindstone cover in which the automatic balance correction device fixing portion is disposed openable and closable, the automatic balance correction device fixing portion can be integrally rotated and opened and closed, so that the rotary whetstone can be replaced. It is possible to easily replace the whetstone without removing the whetstone cover and the automatic balance correction device fixing part. In addition, it is not necessary to manage the air gap every time the grindstone is replaced by simply adjusting the position of the air gap amount between the outer circumference of the rotating portion and the inner circumference of the fixed portion at the initial stage.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a part of a front view of a grinder grindstone head provided with a shaft head structure of a grindstone shaft according to the present invention, in which a grindstone head 20 that moves back and forth with respect to a work (not shown) of the grinder is a grindstone. The shaft 21 is rotatably supported. The grindstone shaft 21 is rotatably and axially immovably supported by a fluid bearing 22, and is rotationally driven by a built-in motor 25. As the fluid bearing 22, various rolling bearings or slide bearings may be used. The hydrodynamic bearing 22 generates a static pressure of pressure oil in a plurality of bearing pockets 23 arranged circumferentially on the inner surface thereof, and the static pressure causes the grindstone shaft 21 to float from the inner surface of the bearing to be supported in the radial direction. Further, it is of a type in which the flange portion 24 of the grindstone shaft 21 is supported in the thrust direction so as not to be axially displaceable by the static pressure generated in the end face bearing pocket (not shown). The motor for driving the grindstone shaft is not limited to the built-in motor 25, and a motor directly connected to the right end (not shown) of the grindstone shaft 21 or a pulley fixed to the same end is driven via a belt type drive mechanism (not shown). A motor may be adopted.

As shown in detail in the sectional view of FIG. 2, a grinding wheel 31 for grinding is detachably attached to the left end of the grinding wheel shaft 21. The grinding wheel 31 is fitted on a cylindrical boss 26 that projects concentrically with the grinding wheel shaft 21, and a plurality of (for example, 10 equiangularly arranged) grinding wheel fixing bolts 34 are used to insert a grinding wheel through a plate 33 and a grinding wheel fixing cap 32. Axis 2
Combined with 1. Here, the automatic balance correction device rotating portion 2 having an annular shape is fitted to the outer periphery of the grindstone fixing cap 32, sandwiched by the plate 33, and screwed to be integrated.
As described above, the whetstone fixing cap 32 sandwiches the whetstone 31 with respect to the whetstone shaft 21, and the plurality of whetstone fixing bolts 34
Are joined by.

On the other hand, the automatic balance correction device fixing portion 3 includes a fixing ring 42 provided on the inner surface of the movable grindstone cover 41.
It is fixed by screwing on. At that time, by positioning in the radial direction and attaching to the fixed grindstone cover 40, a uniform air gap is provided on the outer circumference of the automatic balance correction device rotating portion 2 and the inner circumference of the fixed portion 3. The air gap width is unique to the automatic balance correction device, and by using a clearance gauge, the air gap width can be positioned to a desired air gap width and easily assembled. The movable grindstone cover 41 and the grindstone base 20 are connected to the grindstone 31.
And a pair of hinges 44, which will be described later.
Is supported so as to be rotatable and openable and closable with respect to a fixed grindstone cover 40 described later. As shown in FIG. 1, the fixed grindstone cover 40 covers the upper and lower surfaces, rear surface and one side surface of the grinding wheel 31, and is fixed to a grindstone stand (not shown). In the hinge 44, a mounting portion 40a fixed to the fixed grindstone cover 40 and a support portion 41a fixed to the movable grindstone cover 41 are pivotally attached by a pin 45 having a flange at the center, and the pin 45 is used as a rotating shaft. Moveable wheel cover 41 to fixed wheel cover 40
It can be opened and closed by rotating.

The structure of the shaft head of the grindstone shaft having the balance correction device 1 has been described above. Therefore, the concept of the actual balance correction operation will be briefly described first. As shown in FIG. 2, two rotor portions 2a and 2b having counterweights are attached to the inside of the automatic balance correction device rotating portion 2 so as to freely rotate. The inside of the automatic balance correction device fixing portion 3 screwed and fixed to the fixing ring 42 provided in
Similarly, as shown in FIG. 2, stator portions 3a and 3b that generate a magnetic field for rotating the rotor portions 2a and 2b are attached. Here, the rotor portions 2a and 2b are the stator portions 3a and 3b.
It is possible to freely rotate in the same direction or the opposite direction depending on the direction of the magnetic field. The two rotor portions 2a and 2b having the counterweights rotate so as to balance with the unbalance of the wheel head including the wheel, and are positioned at the balanced points.

Next, the balance correction operation will be specifically described with reference to FIGS. The balance correction operation is performed by the grindstone shaft 21
Reaches a predetermined rotation speed, and the rotation speed is stable. Signals from a rotation sensor 101 incorporated in the balance correction device 1 for magnetically detecting the origin of the rotation angle of the grindstone shaft 21 and a vibration sensor 102 fixed to the grindstone base 20 are transmitted to a controller 10 via an A / D converter (not shown).
Read by 0. At this time, the acceleration signal from the vibration sensor 102 is band-pass filtered to pass only the signal in the frequency band corresponding to the rotation speed, and becomes only the vibration component due to the static imbalance that occurs in synchronization with the rotation speed.

Next, based on the detection signal from the rotation sensor 101 and the detection signal from the vibration sensor 102, the magnitude of the unbalance amount (first moment of mass) and the phase angle from the origin of the rotation angle of the same unbalance amount are determined. It is calculated. That is, as shown in FIG. 6, with the detection signal of the rotation sensor 101 as the origin of the rotation angle, the phase angle θ up to the peak of the acceleration signal of the vibration sensor 102 is calculated. Further, with the magnitude A of the peak value of the acceleration signal of the vibration sensor 102, the magnitude W0 of static imbalance is estimated from W0 = kA. The proportional constant k that correlates the magnitude A of the peak value of the acceleration signal and the magnitude W0 of the static unbalance is that the grindstone shaft 21 is operated with a trial weight having a predetermined static imbalance attached. Can be obtained by

After that, the balance correction device has a built-in
Two counterweights that are annular and have an unbalanced load part (not shown)
The phase angle to be taken is calculated. That is, as shown in FIG. 7, if the size of the static unbalance W0 and the phase angle θ are known, the size and phase of the static unbalance (virtual balance weight) W to be generated by the counterweights W1 and W2. The angle θ + 180 ° is also revealed. Since the magnitude of the static imbalance of each counterweight is known, it is possible to calculate how much the opening angle φ should be placed on both sides of the virtual balance weight W as the center and both counterweights should be arranged. . This calculation only needs to perform a simple geometrical calculation that creates a composite vector corresponding to a virtual balance weight.

In this way, the controller 100 drives both counterweights such that the combination of the mass first moments produced by the two counterweights rotationally moves to a phase angle that offsets the static imbalance W. When both counterweights rotate to proper phase angles, the grindstone shaft 21
The static imbalance that was applied to the balance is canceled by both counterweights, and the static balance is automatically taken. As a result, the vibration applied to the grindstone shaft 21 and the grinding wheel 31 is reduced, the machining accuracy is improved, and the life period in which the grindstone shaft 21 can maintain the original accuracy is extended.

[0022]

[Brief description of drawings]

FIG. 1 is a partial front view of a grinding wheel head having a shaft head structure having an automatic balance correction device according to the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a view on arrow B in FIG.

FIG. 4 is a cross-sectional view of a shaft head structure having a conventional balance correction device.

FIG. 5 is a schematic diagram of a system configuration for balance correction.

FIG. 6 is a time chart showing an imbalance measurement.

FIG. 7: Relationship between unbalance and counterweight

[Explanation of symbols]

1 Automatic balance correction device 2 Automatic balance correction device rotating part 3 Automatic balance correction device fixed part 20 whetstone stand 21 Wheel axis 31 grinding wheel 32 whetstone fixed cap 33 plates 40 Fixed whetstone cover 41 movable whetstone cover 42 fixing ring 100 controller 101 rotation sensor 102 Vibration sensor A vibration peak value Phase angle from θ1 point signal W0 unbalance W virtual weight W1 counterweight W2 counterweight θ2 Unbalanced phase angle φ Balance weight opening angle

Claims (3)

[Claims] 1. An automatic balance correction device having a ring-shaped automatic balance correction device, which has a correction weight inside and is rotated in synchronism with the whetstone shaft, at a shaft head of a grinding device having an annular automatic balance correction device capable of high-speed rotation. The rotating part is located at the head of the grindstone shaft, and the automatic balance correction device fixing part that controls the rotational movement to correct the unbalance against the correction weight of the automatic balance correction device rotating part is provided on the inner surface of the grindstone cover. Head structure of a grindstone shaft with a balanced correction device. 2. The shaft head structure of a grindstone shaft having a balance correcting device according to claim 1, wherein the rotating portion of the automatic balance correcting device is fitted and integrated with an outer periphery of a whetstone fixing cap. 3. The automatic balance correction device fixing portion is positioned with respect to the automatic balance correction device rotating portion by the grindstone cover provided with the automatic balance correction device fixing portion, and can be opened and closed. A shaft head structure of a grindstone shaft having the described balance correction device.