JPH07332352A - Wedge oil film formation type dynamic pressurizing bearing - Google Patents

Abstract

PURPOSE:To provide a wedge oil film formation type dynamic pressurizing bearing which can carry out not only the normal revolution but also the reverse revolution. CONSTITUTION:Concerning a wedge oil film formation type dynamic pressurizing bearing which is constituted so that a bearing member 1 is pushed into a sleeve 4, and each wedge slope 7, 7' is formed between the inner peripheral surface of the bearing member 1 and the outer peripheral surface of a rotary shaft, and the lubricating oil is introduced from the inflow port of the wedge slope, as a rotary shaft 5 revolves, and the oil is discharged from the flow outlet, the bearing member is formed by connecting a plurality of segments 2 and 2' at a thin part 3, and each segment is formed so as to be arranged so that the contact position for the sleeve deflects from the center of the segment, and the contiguous segments are arranged to each pair so that the symmetrical shape is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wedge oil film forming type dynamic pressure bearing which is capable of rotating a shaft in reverse.

[0002]

2. Description of the Related Art Generally, a wedge oil film forming type dynamic pressure bearing has a bearing member consisting of a plurality of segments interposed between a rotary shaft and a sleeve, and a wedge-shaped space, that is, a space between each segment and the rotary shaft. A wedge gradient that is inclined in an arc shape along the circumferential direction of the rotating shaft is formed.The sleeve that encloses the rotating shaft and the bearing member is filled with lubricating oil, and is rotated along with the rotation of the rotating shaft. The lubricating oil is caused to flow toward the tip of the wedge gradient to generate a pressure between the inlet and the outlet, and the resultant force of the pressure pushes the rotating shaft toward the center to ensure stable rotation of the rotating shaft. To hold. This kind of wedge oil film forming type dynamic pressure bearing is used in a place where the displacement of the rotating shaft or the rotating body due to the runout of the rotating shaft or the load is disliked. For example, in a machine tool, it is used for a grindstone shaft bearing of a grinder. .

[0003]

According to the above-mentioned conventional wedge oil film forming type dynamic pressure bearing, the rotation direction of the grindstone shaft is limited to the forward rotation direction, and there is no one capable of reverse rotation. In other devices, the reverse rotation of the shaft is rarely required for the purpose of use, and it is limited to the normal rotation. However, in a dressing device for a grinding wheel (wheel), a wedge oil film forming type dynamic pressure bearing capable of rotating in the forward and reverse directions is desired, and this is a prismatic diamond rotary dresser attached to a rotating shaft to shape the wheel by up-cutting. This is for performing truing and dressing in which the abrasive grains on the wheel surface are crushed by downcutting to form cutting edges. Therefore, it is an object of the present invention to provide a wedge oil film forming type dynamic pressure bearing capable of performing not only forward rotation but also reverse rotation.

[0004]

As a means for technically solving the above-mentioned problems, the present invention is designed such that a bearing member is pushed into a sleeve so that the inner peripheral surface of the bearing member and the outer peripheral surface of the rotary shaft are separated from each other. In the wedge oil film forming type dynamic pressure bearing in which a wedge gradient is formed on the rotary shaft and the lubricating oil is introduced from the inlet of the wedge gradient and discharged from the outlet as the rotary shaft rotates, the bearing member has a plurality of segments. Wedge oil film forming type in which a plurality of pairs are formed by connecting the thin-walled parts and arranging each segment so that the contact position with the sleeve is shifted from the center of the segment and arranging a plurality of pairs so that the shapes of adjacent segments are symmetrical. The main point is dynamic pressure bearings.

[0005]

[Operation] When the bearing member is pushed into the tapered hole of the sleeve, the thin-walled portion is deformed by the deformation, and each segment tries to be displaced with the contact position with the sleeve as the fulcrum. At this time, by shifting the contact position from the center of the segment, the segment is tilted and displaced in an arbitrary direction to form a wedge gradient with the rotation axis. Further, since the adjacent segments are formed symmetrically, the wedge gradients are opposite to each other, and more than one pair are arranged, so that the forward and reverse rotation bearing action is possible.

[0006]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In FIG. 1, 1 is a steel bearing member,
A plurality of (six in the illustrated example) segments 2 are formed into a bush shape in which thin-walled portions 3 are connected, the inner peripheral surface of each segment 2 is formed in an arc shape, and the outer peripheral surface is formed in a non-arcuate shape. As shown in FIG. 3, the contact point P with respect to the taper hole of the sleeve in which the bearing member 1 is mounted is formed to be displaced from the center C of the segment 2 as shown in FIG. or,
Adjacent segments 2, 2'are formed symmetrically and a plurality of pairs (three pairs in the illustrated example) are arranged.

The bearing member 1 thus formed is used as a dynamic pressure bearing of a dressing device for a grinding wheel as shown in FIG. 3, for example. In this dressing device, 4 is a sleeve, and both end portions thereof have tapered holes 4a.
The bearing member 1 is inserted between the tapered hole 4a and the rotary shaft 5 and is pushed by the push screw 6 to be attached.

When the bearing member 1 is pushed in, as shown in FIG. 4, the thin portion 3 is deformed to generate a strain, and the force causes each segment 2, 2'to be tapered in the tapered hole 4a of the sleeve 4.
Pressed against. At this time, as shown in FIG. 5, each of the segments 2 and 2'is displaced with the contact position P with the surface of the tapered hole 4a of the sleeve 4 serving as a fulcrum, and the contact position P is displaced from the center of the segment, so that the segment is inclined. To do.

As a result, a substantially arcuate wedge gradient 7 is formed between the segments 2 and 2'and the rotary shaft 5, and adjacent segments 2 and 2'are formed symmetrically, so that the wedge gradient is formed. 7, 7'are formed in opposite directions, and three pairs of them are continuously formed.

In this case, the rotating shaft 5 is stably supported by the bearing member 1 regardless of whether the rotating shaft 5 rotates in the forward or reverse direction. That is, FIG. 6 shows the wedge oil film formation and the pressure distribution state during the forward and reverse rotations (however, in order to facilitate understanding, the circular motion is replaced with a linear motion, and a state cut in the axial direction is described as being expanded).

FIG. 6 (a) shows a case where the rotary shaft 5 rotates counterclockwise (counterclockwise in FIG. 5). The rotation of the rotary shaft 5 causes the lubricating oil 8 to be narrower than the segment 2. Through the inlet 2a, the outlet 2b is wide, and for the segment 2 ', the inlet 2'a is wide and the outlet 2'b is narrow, and this operation is repeated. It will be.

Therefore, when the lubricating oil 8 passes through the segment 2 ', the flow passage gradually narrows and the pressure increases, and the pressure distribution is in the positive (positive) pressure state as shown in FIG. , The force that pushes the rotary shaft 5 toward the center. Also, lubricating oil 8
When passing through the segment 2, the flow path becomes wider and the pressure becomes lower, and the pressure distribution is a negative (negative) pressure state as shown in Fig. 6 (a), and the force that attracts the rotating shaft 5 become.

Since the positive (positive) pressure generated in the segment 2'is several tens of times higher than the negative (negative) pressure generated in the segment 2, as a result, the rotating shaft 5 receives a force toward the center, Moreover, since the three segments 2'are arranged so as to surround the rotary shaft 5 as described above, the segments 2'are pushed by a strong force from three directions toward the center at intervals of 120 degrees in the circumferential direction, and the center runout occurs. It is possible to maintain stable rotation without doing.

On the other hand, in FIG. 6B, the rotary shaft 5 rotates clockwise (see FIG.
In this case, the lubricating oil 8 flows toward the segment 2 from the wider inlet 2b toward the narrower outlet 2a, contrary to the counterclockwise rotation. For the segment 2 ', it flows from the narrower inlet 2'b toward the wider outlet 2'a.

Therefore, the relationship of pressure distribution to the segments 2 and 2'is opposite to the above, and the large positive (positive) pressure generated in the segment 2 causes the rotating shaft 5 to receive a strong pressure toward the center, and the segment 2 As described above, since the three rotating shafts 5 are arranged so as to surround the rotating shaft 5, the rotating shaft 5 is pushed by a strong force in the center direction from three directions with an interval of 120 degrees in the circumferential direction. Stable rotation without doing.

That is, when the rotary shaft 5 rotates counterclockwise, the segment 2'works as a main element of the bearing, and when it rotates right, the segment 2 works as a main element of the bearing. The action as a dynamic pressure bearing can be obtained.

FIG. 3 shows an example in which the wedge oil film forming type dynamic pressure bearing according to the present invention is mounted on a CBN wheel (cubic boron nitride grindstone) dressing device. In this case, the main shaft (rotating shaft 5) is rotated. An inverter motor or a servomotor is used as the motor 9 for rotating the prismatic diamond rotary dresser 10 attached to the tip of the rotary shaft 5.
At this time, the peripheral speed of the prismatic diamond rotary dresser 10 is adjusted via the pulleys 11 and 12 to be about 0.9 times the peripheral speed of the grinding wheel.

The CBN wheel 13 is dressed using this prismatic diamond rotary dresser 10. As shown in FIG. 7 (a), the truing is performed in the normal rotation (up cut) to obtain the rotation accuracy of the grinding wheel, and then the Make a cutting edge on the abrasive grain by dressing in reverse (down cut) as shown in).

In general, the conventional dressing methods do not allow cutting edges to be formed on the abrasive grains, so the tangential grinding resistance immediately after dressing is high. It was necessary to grind a considerable amount of grinding allowance cross-sectional area per unit circumference length of the wheel by the time the temperature decreased. Until then, unless the grinding allowance cross-sectional area per unit circumference length is reduced and grinding is performed, the work is flexed and burned due to the high resistance, and high-precision grinding cannot be performed.

However, C dressed as described above
When the BN wheel 13 was ground, the tangential grinding resistance was low and constant irrespective of the grinding allowance cross-sectional area per wheel circumference length as shown in FIG. 8, and highly accurate and highly efficient grinding was possible.

The wedge oil film forming type dynamic pressure bearing according to the present invention is not limited to a dressing device, but can be widely applied as a dynamic pressure bearing for other precision equipment and the like.

[0022]

As described above, according to the present invention,
It is possible to provide a wedge oil film forming type dynamic pressure bearing that can be rotated in forward and reverse directions, and it is possible to widely apply it as a dynamic pressure bearing for dressing devices and other various devices.

[Brief description of drawings]

FIG. 1 is a sectional view perpendicular to the axis of a wedge oil film forming type dynamic pressure bearing according to the present invention.

FIG. 2 is a sectional view of the same in the axial direction.

FIG. 3 is an axial sectional view of a main part of the dressing device.

FIG. 4 is a sectional view of a main part of the same taken at right angles to the axis.

FIG. 5 is an enlarged cross-sectional view of the bearing portion perpendicular to the axis.

6 (a) and 6 (b) are explanatory views respectively showing a wedge oil film formation and a pressure distribution state during forward and reverse rotations.

FIG. 7 shows a wheel dressing state,
(A) is an illustration of up-cut truing, and (B) is an illustration of down-cut dressing.

FIG. 8 is a graph showing the relationship between tangential grinding resistance and ground surface roughness due to grinding with a dressed wheel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bearing member 2, 2 '... Segment 3 ... Thin part 4 ... Sleeve 4a ... Tapered hole 5 ... Rotating shaft 6 ... Push screw
7, 7 '... Wedge gradient 8 ... Lubricating oil 9 ... Motor 1
0 ... Square diamond rotary dresser 11, 1
2 ... pulley 13 ... wheel

Claims (1)

[Claims] 1. A bearing member is pushed into a sleeve to form a wedge gradient between an inner peripheral surface of the bearing member and an outer peripheral surface of a rotary shaft, and lubricating oil is introduced into the inlet port of the wedge gradient as the rotary shaft rotates. In the wedge oil film forming type dynamic pressure bearing that is made to enter from the above and come out from the outlet, the bearing member is formed by connecting a plurality of segments with a thin portion, and each segment has a contact position to the sleeve of the segment. A wedge oil film-forming dynamic pressure bearing characterized in that a plurality of pairs are formed such that they are displaced from the center and the shapes of adjacent segments are symmetrical.