KR101221686B1 - Pre-load control device of bearing for machine tool - Google Patents

Abstract

The present invention is a rod-shaped main shaft is formed at one end with a small end diameter is formed to be rotatable, a housing disposed to surround the main shaft, is interposed between the housing and the main shaft is coupled adjacent to the step, It provides a bearing preload control device for a machine tool comprising a bearing portion for supporting the main shaft rotatably in the housing and an eccentric mass for pressing the bearing portion in the stepped direction when the main shaft rotates.
The bearing preload control device for machine tools according to the present invention can automatically apply an appropriate preload corresponding to the rotational speed of the main shaft by the eccentric mass to cope with a wide range of changes in the main shaft rotational speed of the machine tool with a simple configuration and low cost. Can also have the effect of enabling a precise response.

Description

Preload control device for machine tools {Pre-load control device of bearing for machine tool}

The present invention relates to a bearing preload adjusting device for a machine tool, and more particularly, to a bearing preload adjusting device for a machine tool capable of automatically applying a preload to a bearing by generating a centrifugal force on an eccentric mass when the main shaft rotates.

It is necessary to apply an appropriate preload to the ball bearing which rotatably supports the main shaft inside the housing of the machine tool. This is achieved by low speed roughing and high speed finishing in one machine tool. In low speed roughing, large preload is required to increase the rigidity of the spindle and to suppress vibration. This is because a low preload is necessary to avoid heat generation.

In general, the preload adjusting method of the bearing is known a conversion preloading method, a multi-stage fixed position preloading method, an automatic variable preloading method. The conversion preloading method is a method of changing the preload from the fixed position to the positive pressure when the rotational speed of the main shaft changes to a predetermined number of revolutions or more, which has the disadvantage that the stiffness of the main shaft is deteriorated at the intermediate speed after the conversion to the constant pressure preload. There is a design difficulty because the deformation between the bearings and the deformation of the preload mechanism should be taken into consideration for the correct setting of. Therefore, by using the automatic variable preloading method, the preload can be adjusted by the centrifugal force and spring pressure according to the rotation of the main shaft, so that the preload can be adjusted without the need for complicated mechanical configuration or electrical equipment.

However, due to the preload adjustment depending on the elasticity of the spring, the ability to adjust the preload for centrifugal force exceeding the elasticity of the spring is inferior, causing a problem that cannot cope with a wide range of rotational speed changes.

The present invention relates to a bearing preload adjusting device for a machine tool, and more particularly, to provide a bearing preload adjusting device for a machine tool which can generate a centrifugal force on an eccentric mass due to the rotational force of the main shaft and automatically apply a preload to the bearing. There is a purpose.

The present invention is a rod-shaped main shaft is formed at one end with a small end diameter is formed to be rotatable, a housing disposed to surround the main shaft, is interposed between the housing and the main shaft is coupled adjacent to the step, And a bearing portion for supporting the main shaft so as to be rotatable inside the housing, and an eccentric mass for pressing the bearing portion in the stepped direction when the main shaft rotates, wherein the bearing portion is fixed to the inside of the housing and has a shaft of the main shaft. The outer ring body having an inclined surface formed on the inner circumferential surface in the direction; Ball bearing is provided to reduce the preload in the case of deviation from the inclined surface of the outer ring body The eccentric mass is an elastic member having a ring shape having elasticity, coupled to the main shaft adjacent to the inner ring body, and formed with a plurality of through holes at equal intervals along the circumferential direction adjacent to the outer circumferential surface thereof, Eccentric weights are coupled to the through hole of the elastic member so as to be eccentric.

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The eccentric weight may press the inner ring body such that the ball bearing is disposed on the inclined surface by the center of gravity when the main shaft rotates.

The elastic member may be bent to press the inner ring body by the eccentric weight when the main shaft rotates, and may return the eccentric weight to its original position when the rotational force of the main shaft is released.

The bearing preload control device for machine tools according to the present invention can automatically apply an appropriate preload corresponding to the rotational speed of the main shaft by the eccentric mass to cope with a wide range of changes in the main shaft rotational speed of the machine tool with a simple configuration and low cost. Can also have the effect of enabling a precise response.

1 is a cross-sectional view showing a bearing preload adjusting device for a machine tool according to an embodiment of the present invention;
2 is a cross-sectional view showing a state in which the eccentric mass shown in FIG. 1 is operated;
FIG. 3 is an exploded perspective view showing the eccentric mass shown in FIG. 1. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately The present invention should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention.

1 is a cross-sectional view showing a bearing preload adjusting device 100 for a machine tool according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a state in which the eccentric mass 140 shown in FIG. It is an exploded perspective view showing the eccentric mass 140 shown,

1 to 3, the bearing preload adjusting apparatus 100 for a machine tool according to the present invention includes a main shaft 110 rotating inside the machine tool and a housing 120 disposed to surround the main shaft 110. ), And an eccentric mass provided to press the bearing part 130 according to a rotational force of the bearing part 130 and the main shaft 110 provided to rotate the main shaft 110 from the housing 120. 140).

The main shaft 110 is rotated by receiving a driving force in the shape of a rod, the end 111 is formed at one end so that the bearing portion 130 is coupled.

The bearing part 130 includes an outer ring body 131 coupled to an inner circumferential surface of the housing 120, an inner ring body 133 coupled to an outer circumferential surface of the main shaft 110, and the outer ring body 131 and an inner ring body ( And a ball bearing 135 interposed between the 133.

The outer ring body 131 forms an overall outer shape of the bearing part 130, and an inclined surface 132 is formed on an inner circumferential surface thereof. The inclined surface 132 is inclined in the coupling direction of the main shaft 110, that is, the axial direction of the main shaft 110, and when the ball bearing 135 is in contact with the inclined surface 132 and the inclined surface 132 The contact area of the ball bearing 135 is formed to increase in shape. Therefore, one end surface of the inclined surface 132 is formed to correspond to the outer circumferential surface of the ball bearing 135, and when the ball bearing is disposed on the inclined surface 132, the ball bearing 135 is formed in line contact with the inclined surface. When the ball bearing 135 deviates from the 132, the ball bearing 135 comes into point contact with the inner circumferential surface of the outer ring body 131. This exemplarily illustrates a case in which the inclined surface 132 is formed as a curved surface in a shape corresponding to the outer circumferential surface of the ball bearing 135. When the inclined surface 132 is formed in a straight line, the inclined surface 132 is formed to be in constant point contact and is linear. When the ball bearing 135 is disposed on an inclined surface (not shown), the ball bearing 135 may be formed to press the linear inclined surface to increase the preload.

The bearing part 130 may slide in the axial direction of the main shaft 110 by a gap formed between the stepped 111 and the inner ring body 133 on the outer circumferential surface of the main shaft 110.

When the rotational speed of the main shaft 110 is a high speed, the pressing member 146 presses the inner ring body 133 so that the ball bearing 135 contacts the inclined surface 132 position of the outer ring body 131. In this case, the contact area between the ball bearing 135 and the outer ring body 131 is increased to generate a high preload in the bearing part 130.

On the contrary, when the rotational speed of the main shaft 110 is slow or stopped, the pressure applied to the inner ring body 133 is released by the pressing member 146, and the ball bearing 135 is moved by the centrifugal force. As the force to escape from the inclined surface 132 pushes the inner ring body 133 to move to its original position, the contact area between the ball bearing 135 and the outer ring body 131 is reduced, so that the preload is applied to the bearing part 130. Will decrease.

The eccentric mass 140 has a function of pressing the bearing part 130. The eccentric mass 140 includes an elastic member 141 coupled to the main shaft 110 and an eccentric weight 145 eccentrically coupled to the elastic member 141.

The elastic member 141 is a ring-shaped thin plate is formed in the inner center through the coupling hole 142 penetrating so as to be adjacent to the inner ring body 133 on the main shaft 110, the coupling hole ( At the periphery of 142, a plurality of through holes 143 are formed at equal intervals along the circumferential direction. In addition, the elastic member 141 is formed of a material having elasticity, the direction in which the center of gravity of the eccentric weight 145 is adjusted by the centrifugal force of the eccentric weight 145 generated according to the rotational speed of the main shaft 110 Bent to

The eccentric weight 145 is a pressing member 146 provided to press the inner ring body 133 from one side of the through hole 143, when the main shaft 110 is rotated from the other side of the through hole 143 It is coupled to the pressing member 146 and includes an eccentric member 147 having a greater weight than the pressing member 146 so that the center of gravity is disposed. Therefore, the eccentric weight 145 is coupled such that its center of gravity is eccentrically toward the eccentric member 147 with respect to the through hole 143.

The eccentric mass 140 according to the present invention is illustrated to be coupled to the stepped 111 and another stepped 111 to which the bearing part 130 is coupled on the main shaft 110, but without the other stepped 111. The eccentric mass 140 may be coupled to the outer circumferential surface of the main shaft 110.

Therefore, the bearing preload adjusting device 100 for a machine tool according to the present invention automatically presses the preload corresponding to the rotational speed of the main shaft 110 by the centrifugal force of the eccentric mass 140 to the bearing part 130. Can be.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: bearing preload adjusting device 110: spindle
111: step 120: housing
130: bearing portion 131: outer ring body
132: inclined surface 133: inner ring body
135: ball bearing 140: eccentric mass
141: elastic member 142: coupling hole
143: through-hole 145: eccentric weight
146: pressure member 147: eccentric member

Claims (5)

The main shaft is formed in a rod shape at one end with a small step, the main shaft is provided to be rotatable, a housing disposed to surround the main axis, and is interposed between the housing and the main axis to be adjacent to the step. And a eccentric mass for pressing the bearing part in the stepped direction when the main shaft rotates, and the bearing part supporting the rotatable inside the housing, wherein the bearing part is fixed to the inside of the housing and in the axial direction of the main shaft. An outer ring body having an inclined surface formed in the outer ring body, the inner ring body fixed to the outer circumferential surface of the main shaft and rotating together with the main shaft, and interposed between the outer ring body and the inner ring body to increase the preload and increase the preload Includes a ball bearing provided to reduce preload in case of deviation from the slope of the sieve In the bearing preload adjustment for machine tools,
The eccentric mass is an elastic member having an elastic ring shape, coupled to the main shaft adjacent to the inner ring body, and formed with a plurality of through holes at equal intervals along the circumferential direction adjacent to an outer circumferential surface thereof, and the elastic so that the center of gravity is eccentric. Bearing preload adjusting device for machine tools comprising eccentric weights coupled to the through hole of the member.
delete delete The method according to claim 1,
The eccentric,
And a preload control device for a machine tool for pressurizing the inner ring body such that the ball bearing is disposed on the inclined surface by the center of gravity when the main shaft rotates.
The method of claim 4,
The elastic member
And the main shaft is bent to press the inner ring body by the eccentric weight when the main shaft rotates, and returns the eccentric weight to its original position when the rotational force of the main shaft is released.

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