JP4305110B2 - Bearing device - Google Patents

Description

  The present invention relates to a bearing device such as a spindle unit for machine tools that is lubricated with a lubricant such as grease.

  A spindle unit for a machine tool as a bearing device is a spindle (main shaft) inserted through a housing and rotatably supported by the housing via a plurality of rolling bearings. As a lubrication means of such a bearing, grease as a lubricant is filled in the bearing so as to lubricate the rolling elements, the outer ring, and the inner ring (for example, see Patent Document 1).

As other bearing lubrication means, an oil-air lubrication system, an oil mist lubrication system, and a jet lubrication system are well known.
JP 2003-56573 A

  In recent years, the speed of machine tools has been increased, and there has been a problem in durability only with the grease filled in the initial stage. Usually, since the lubrication life due to grease deterioration is shorter than the rolling fatigue life of the bearing raceway surface, a relatively large amount of grease may be enclosed in order to enable continued use of the bearing device for a longer period. When a large amount of grease is sealed in this way, heat generated due to the agitation resistance of the grease increases, which affects the processing accuracy of the machine tool and slows the familiarity time of the grease. In addition, the temperature of the grease may increase and the bearing may be seized.

  Further, the oil-air lubrication method, the oil mist lubrication method, and the jet lubrication method are configured to supply oil from the outside of the bearing device, and thus have a drawback that a complicated and expensive device is required.

A bearing device according to the present invention is a bearing device that lubricates the inside of an angular ball bearing that rotatably supports a spindle on a housing with a lubricant, and the angular ball bearing is an outer ring fixed to an inner peripheral surface of the housing. And an inner ring fixed to the outer diameter surface of the spindle, and a rolling element, and an annular ring that is continuously formed in the outer circumferential surface of the angular ball bearing in the circumferential direction and opens to the outer circumferential surface A lubricant reservoir, a lubricant supply hole that communicates the lubricant reservoir with the inside of the angular ball bearing, and a through-hole that communicates the exterior with the lubricant reservoir are provided in the housing. a lubricant which is stored a configuration to pull through the lubricant supply holes inside the rolling bearing by a negative pressure relative to the outside due to a temperature drop in the unit housing, the lubricant supply hole, in the raceway surface of the outer ring And it is characterized in that it is formed in a counter bore for use line. An example of the lubricant is grease.

According to the bearing device of the present invention, the following principle can be utilized. That is, the temperature inside the housing rises during rotation of the spindle, and the temperature drops when stopped. When the temperature inside the housing rises, the internal pressure increases due to the expansion of air inside the housing, and the air inside the housing goes out. When the temperature inside the housing decreases due to the stop of the spindle, the inside of the housing becomes negative pressure, so that air is drawn into the housing by the negative pressure. In the bearing device of the present invention, when the air is drawn in by this negative pressure, the lubricant (grease) in the lubricant reservoir is drawn into the angular ball bearing through the lubricant supply hole. The agent is naturally lubricated. In this way, the bearing device uses the principle that the internal pressure increases with the temperature rise during the rotation of the spindle and decreases to a negative pressure when the spindle is stopped. The device is not necessary, that is, the lubricant can be supplied into the bearing device easily and inexpensively.

  The bearing device of the present invention is particularly effective in the case of high-speed rotation of the spindle of a machine tool. The dn value (bearing inner diameter (mm) × rotational speed (rpm)) is effective at 500,000 to 1,200,000, and it is considered that the service life is increased to 3 to 50 times by slightly lubricating the lubricant. .

Further, the through hole formed in the housing is preferably provided with a ventilation filter. Such filters, the air bearing device outside enters into the through-hole is allowed, preferably can be prevented from impure product is mixed.

  According to the bearing device of the present invention, a lubricant such as grease can be easily pulled into the bearing at a low cost.

  An embodiment of a bearing device according to the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing the main part of the spindle unit for machine tools, FIG. 2 is a front sectional view showing the main part of the unit, and FIG. 3 is a side sectional view showing the front part of the unit.

  In FIG. 3, a spindle unit 1 for a machine tool as a bearing device includes a spindle (main shaft) 2 having a tool mounting hole 2a at a front end, and a plurality of rolling bearings 5a, 5b, 5c that rotatably support the spindle 2. 5d and a housing 7 that covers these ball bearings 5a, 5b, 5c, and 5d. The housing 7 includes a cylindrical outer cylinder 10, a front lid 11 fixed to the front end surface of the outer cylinder 10, and a rear lid (not shown) fixed to the rear end surface of the outer cylinder 10. The outer cylinder 10 has a flange portion 10a fixed to the machine tool side.

  Each of the rolling bearings 5a, 5b, 5c, and 5d is of an angular ball bearing (ball bearing) type including an outer ring 6, an inner ring 8, a rolling element 9, and a cage (not shown). A cylindrical outer ring spacer 13 is interposed between the outer rings 6 of the ball bearings 5a, 5b, 5c, and 5d. The outer ring 6 of the last ball bearing 5 d is locked to the inner diameter step portion 10 a of the outer cylinder 10, and the foremost ball bearing 5 a is locked to the front lid 11. Therefore, the outer ring 6 of each ball bearing 5 a, 5 b, 5 c, 5 d is fixed to the inner peripheral surface of the outer cylinder 10.

  A cylindrical inner ring spacer 14 is interposed between the inner rings 8 of the ball bearings 5a, 5b, 5c, and 5d. The inner ring 8 of the ball bearing 5d at the rearmost part is locked by a holding ring 15 fitted to the spindle 2, and the inner ring 8 of the ball bearing 5a at the foremost part The inner ring presser 14a interposed therebetween is locked. Therefore, the inner ring 8 of each ball bearing 5a, 5b, 5c, 5d is fixed to the outer diameter surface of the spindle 2 so as to be integrally rotatable. The rotation side of the spindle 2, the inner ring spacer 14 and the inner ring presser 14a has a gap such as a labyrinth seal with respect to the fixed side of the housing 7 and the outer ring spacer 13 or the like.

  As shown in FIG. 1 and FIG. 2, an annular lubricant reservoir 17 that opens to the outer peripheral surface of the outer ring 6 of each ball bearing 5 a, 5 b, 5 c, 5 d is formed continuously in the circumferential direction. . Moreover, the outer ring 6 is formed with a lubricant supply hole 20 for supplying the grease 18 in the lubricant reservoir 17 to the inside of the ball bearing. Specifically, a plurality of lubricant supply holes 20 are provided in the circumferential direction of the outer ring 6, and each lubricant supply hole 20 is provided on the counter bore 6 b side with respect to the action line X on the raceway surface 6 a of the outer ring 6, and lubricated. It is formed so as to penetrate the bottom surface 17 a of the agent reservoir 17. The diameter of the lubricant supply hole 20 is appropriately determined depending on the type of grease and the like so that a desired amount of grease can flow. The lubricant supply hole 20 may be single.

  A through-hole 21 communicating with the inside and outside of the outer cylinder 10 is formed in the outer cylinder 10 of the housing 7 and corresponding to the lubricant reservoir 17. The diameter of the through hole 21 is set to be approximately the same as the groove width of the lubricant reservoir 17. A single through hole 21 may be provided, or a plurality of through holes 21 may be provided in the circumferential direction of the outer cylinder 10 as indicated by a virtual line in FIG. The grease 18 may be filled in the lubricant reservoir 17 in advance before assembling the machine tool spindle unit 1 or may be filled in the lubricant reservoir 17 through the through hole 21 after assembly. Good. Moreover, replenishment of the grease 18 to the lubricant reservoir 17 can be easily performed through the through hole 21.

  A filter 22 is detachably provided in the through hole 21. As the filter 22, for example, Gore-Tex (registered trademark) having waterproofness and air permeability can be adopted. The filter 22 allows the passage of air but can prevent the grease 18 from flowing backward, and prevents impurities from entering the through hole 21.

  The machine tool spindle unit 1 having the above-described configuration processes a workpiece by attaching a cutting tool (not shown) to the tool attachment hole 2a formed at the front end of the spindle 2 and rotating the spindle 2 at a high speed. In the spindle unit 1 for machine tools, a lubricant supply hole 20 is formed in the outer ring 6 of each of the ball bearings 5a, 5b, 5c, and 5d. The lubricant supply hole 20 is formed on the raceway surface 6a of the outer ring 6. Since it is formed on the counter bore 6b side with respect to the action line X, it does not hinder the rolling elements 9 rolling on the raceway surface 6a. When the spindle 2 rotates at high speed, the temperature in the spindle unit 1 (in the housing 7) rises. At this time, the air inside is heated and expanded to increase the internal pressure, and the air is discharged to the outside through the gap between the front and rear of the spindle unit 1.

  When the spindle unit 1 stops, the temperature inside the spindle unit 1 decreases to room temperature. As the internal temperature decreases, the inside of the spindle unit 1 is in a negative pressure state as compared with the outside. Naturally, the inside of each ball bearing 5a, 5b, 5c, 5d (between the outer ring 6 and the inner ring 8) is also in a negative pressure state. For this reason, air outside the spindle unit 1 tends to be drawn into the spindle unit 1 from the gap between the front and rear of the housing 7. At the same time, since the external air passes freely through the filter 22 and can enter the through hole 21, the grease 18 stored in the lubricant storage portion 17 is passed through the lubricant supply hole 20 through the ball bearings 5 a, 5 b, An appropriate amount of grease is supplied inside 5c and 5d, and the life of the grease is prolonged.

  In the present embodiment, since a plurality of lubricant supply holes 20 are provided in the circumferential direction of the outer ring 6, the grease 18 can be uniformly supplied to the ball bearing. In addition, by providing the lubricant reservoir 17 on the outer ring 6, the distance between the lubricant reservoir 17 and the inside of the ball bearing can be reduced, and the grease 18 can be efficiently and reliably applied by the negative pressure inside the spindle unit 1. Can be supplied to the bearing.

  Furthermore, when replenishing the lubricant reservoir 17 with the grease 18, each filter 22 can be taken out from the through hole 21, and the grease 18 can be easily filled into the lubricant reservoir 17 from the through hole 21.

  Furthermore, the grease 18 can be filled not only in the lubricant reservoir 17 provided in the outer ring 6 but also in the through hole 21 formed in the outer cylinder 10 of the housing 7. In this case, a lubricant reservoir is substantially formed in the outer ring 6 and the housing 7.

  The material of the filter 22 is not particularly limited, and an ULPA filter (Ultra Low Penetoration Airfilter), a HEPA filter (High Efficiency Particulate Airfilter), a MEPA filter (Medium Efficiency Particulate Airfilter), a special filter, or the like can be employed. Furthermore, it is possible to provide an air filter sensor for detecting clogging of the filter 22.

  In addition, when the spindle unit 1 is stopped (the rotation of the spindle 2 is stopped) as described above, the grease 18 stored in the lubricant reservoir 17 is used by utilizing the negative pressure inside the spindle unit 1. Besides lubricating the ball bearings 5a, 5b, 5c, and 5d, the spindle 2 that rotates at a high speed is decelerated to a low speed to reduce the temperature inside the spindle unit 1, and the grease 18 is supplied to the ball bearing 5a, It is also possible to lubricate the inside of 5b, 5c, 5d.

Sectional drawing which shows the principal part of the bearing apparatus of this invention Sectional drawing which shows the front of the bearing apparatus of this invention Sectional drawing of the front part of the bearing device of the present invention

Explanation of symbols

5a, 5b, 5c, 5d Ball bearing (rolling bearing)
6 Outer ring 10 Housing 17 Lubricant reservoir 18 Grease (lubricant)
20 Lubricant supply hole 21 Through hole

Claims (3)

A bearing device that lubricates the inside of an angular ball bearing that rotatably supports a spindle in a housing with a lubricant,
The angular ball bearing has an outer ring fixed to the inner peripheral surface of the housing, an inner ring fixed to the outer diameter surface of the spindle, and a rolling element,
An annular lubricant reservoir formed continuously in the circumferential direction on the outer ring of the angular ball bearing and opened in the outer circumferential surface, and a lubricant communicating with the lubricant reservoir and the inside of the angular ball bearing A replenishment hole,
The housing is provided with a through hole that communicates the outside with the lubricant reservoir,
A lubricant which is stored in the lubricant reservoir portion is configured to draw through the lubricant supply holes inside the rolling bearing by a negative pressure relative to the outside due to a temperature drop in the housing,
The lubricant supply hole is formed on the counter bore side with respect to the action line on the raceway surface of the outer ring .   The bearing device according to claim 1, wherein a ventilation filter is provided in the through hole of the housing.   The bearing device according to claim 1, wherein the bearing device is used in a spindle unit for a machine tool.

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