Rolling bearing device

Abstract

This rolling bearing device is provided with: an angular contact ball bearing (10) in which a grease composition (15) is sealed; and a lubricant oil supply mechanism (20), wherein a detection unit (26) detects the temperature, vibration, and the like of the bearing (10), a control unit (22) determines the amount of oil supply and the timing of oil supply, and an oil is supplied from a tank (25) to the bearing (10) by a pump (24). A porous elastic body (50) having lubricant permeability is loaded in a casing (48) of a positive displacement pump (46), and a required amount of a lubricant is discharged into a bearing space by pressing the porous elastic body (50).

Description

Rolling bearing device

[0001] The present invention relates to a rolling bearing device including a rolling bearing and a lubricating oil supply mechanism, and a mechanical device such as a spindle device for a machine tool incorporating the rolling bearing device.

[0002] The main shaft of a machine tool is preferably rotated at high speed to increase the machining efficiency, and various lubrication techniques are applied to its bearings. As lubrication methods suitable for a high-speed rotating main shaft, for example, methods such as air-oil lubrication and oil mist lubrication are known.

[0003] In recent years, in the field of machine tools, the need to respond to carbon neutrality and further cost reduction has been increasing, and along with that, the need for grease lubrication has been increasing. Grease lubrication is environmentally friendly because it does not require an air-oil supply device as auxiliary equipment necessary for air-oil lubrication and a structure for injecting air-oil into the bearing, and can suppress initial costs and operating costs.

[0004] On the other hand, since grease lubrication lubricates only with the initial grease composition enclosed at the time of bearing assembly, in high-speed rotation applications, deterioration is accelerated due to heat generation of the bearing, and it is difficult to ensure lubrication durability. Therefore, in grease lubrication, a response to further high-speedization (improvement of lubrication durability) is required.

[0005] Regarding this, Patent Document 1 discloses a rolling bearing device including a rolling bearing and a lubricating oil supply mechanism connected to the bearing. The lubricating oil supply mechanism has a holding portion that holds lubricating oil and a supply portion that supplies the lubricating oil from the holding portion to a bearing space between the outer ring and the inner ring of the rolling bearing. According to such a configuration, it is possible to replenish lubricating oil even in grease lubrication. The lubricating oil supply mechanism includes a power generation portion that generates electric power, and operates a micropump with the electric power from the power generation portion to supply the lubricating oil into the rolling bearing (Patent Document 1).

[0006] Furthermore, a diaphragm-type pump used in a lubrication oil supply mechanism for a rolling bearing device is known to use a piezoelectric element in the drive unit, and it is known that felt or sponge is provided in the tank that holds the lubricating oil to retain it (Patent Document 2, paragraph

[0028] ).

[0007] Patent No. 6495700 Patent No. 6446887

[0008] However, Patent Document 1 does not provide specific details on the amount or timing of lubrication oil supplied to the rolling bearing from the lubrication oil supply mechanism. In this regard, it is usually assumed that lubrication will be supplied at regular intervals as part of time-based maintenance (TBM), regardless of the lubrication state of the rolling bearing. In that case, there will be cases where lubrication oil is supplied at times when it is not needed, which is not very efficient, and it will be necessary to enlarge the tank of the holding part to account for the unnecessary amount, and to further improve the reliability of each component.

[0009] As a result, the lubrication oil supply mechanism becomes larger, which degrades the performance of machine tools, particularly those used at high speeds, such as spindle devices for machine tools, where compactness is generally required in terms of machining rigidity, runout accuracy, and dynamic balance.

[0010] Furthermore, the conventional lubrication oil supply mechanisms (lubrication devices) described above require control over the opening and closing of valves related to the pump and the discharge volume of the injection nozzle in order to prevent oil leakage and maintain strict airtightness of the pump, as well as the stable discharge of an appropriate amount of lubricating oil. In particular, with high-speed rotating rolling bearings, if excessive oil enters the rolling section, the heat generated by agitation can cause a rapid increase in the bearing's temperature, leading to bearing seizure. Similarly, if the amount of lubricating oil discharged is insufficient, the rolling section cannot be supplied with the necessary oil, which can also lead to seizure. On the other hand, if complex mechanisms and structures are incorporated to prevent oil leakage and insufficient airtightness of the pump unit, it leads to an increase in the size of the lubrication oil supply mechanism and the machine body, and a rise in manufacturing costs.

[0011] This invention has been made in view of these circumstances, and aims to provide a rolling bearing device in which a lubricating oil supply mechanism is attached to the rolling bearing, in order to ensure lubrication durability in grease lubrication even under high-speed rotation conditions, by supplying lubricating oil efficiently and without waste in accordance with the lubrication state of the rolling bearing through condition-based maintenance (CBM).

[0012] Furthermore, the present invention aims to miniaturize rolling bearing devices, and also to miniaturize mechanical devices used in high-speed rotation, such as spindle devices for machine tools, that incorporate rolling bearing devices.

[0013] Furthermore, in addition to the above-mentioned problems, the present invention also aims to enable the temporary retention of lubricating oil and the stable discharge of an appropriate amount in a lubrication device attached to a rolling bearing, and to ensure that the discharge of an appropriate amount of lubricant in the lubrication device is stable and reliable with a simple mechanism.

[0014] To solve the above-mentioned problems, the present invention provides a rolling bearing device comprising a rolling bearing and a lubricating oil supply mechanism, wherein the rolling bearing comprises an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a grease composition sealed in the bearing space between the inner ring and the outer ring, and the lubricating oil supply mechanism comprises a holding part for holding lubricating oil, a supply part for supplying the lubricating oil held in the holding part to the bearing space of the rolling bearing, a detection part for detecting a lubrication characteristic value (lubrication characteristic index) related to the lubrication state of the rolling bearing, and a control unit for controlling the operation of the supply unit, wherein the control unit is configured to determine the amount of oil supplied from the supply unit and the timing of oil supply according to the output of the detection unit.

[0015] This configuration allows for the timely and appropriate supply of lubricating oil according to the lubrication state of the rolling bearing, thereby maintaining good grease lubrication and contributing to the long-term stabilization of the rolling characteristics and improvement of the lifespan of the rolling bearing. Furthermore, because lubricating oil can be supplied efficiently according to the lubrication state of the rolling bearing, there is less wasted lubricating oil compared to supplying lubricating oil at fixed intervals regardless of the lubrication state. This allows for a smaller lubricating oil supply mechanism, including the retaining part, and contributes to the overall miniaturization of the rolling bearing device.

[0016] In the rolling bearing device according to the invention, the detection unit may be configured to detect at least one of the following as the lubrication characteristic value: the temperature, vibration, and rotational torque of the rolling bearing, as well as the color, light transmittance / reflectance, odor, specific gravity, acid value, iron content, and moisture content of the grease composition.

[0017] Furthermore, in the rolling bearing device according to the invention, the detection unit can detect a plurality of lubrication characteristic values ​​from among the lubrication characteristic values, and the control unit can drive the supply unit to supply lubricating oil to the bearing space when the change in two or more of these lubrication characteristic values ​​exceeds a predetermined set value. In this case, one of the plurality of lubrication characteristic values ​​can be the change in the rotational torque of the rolling bearing.

[0018] Alternatively, in the rolling bearing device according to the invention, the detection unit may detect a plurality of lubrication characteristic values ​​from among the lubrication characteristic values, and the control unit may drive the supply unit to supply lubricating oil to the bearing space when two or more of the lubrication characteristic values ​​themselves exceed a predetermined set value. In this case, one of the plurality of lubrication characteristic values ​​may be the value of the rotational torque of the rolling bearing.

[0019] Furthermore, in the rolling bearing device according to the invention, the predetermined set value can be determined based on the relationship between a plurality of lubrication characteristic values ​​measured when the rolling bearing and the grease composition are in a normal state.

[0020] Furthermore, in the rolling bearing device according to the invention, a configuration can be adopted in which spacers adjacent to the rolling bearing in the axial direction are further provided, and the lubricating oil supply mechanism is mounted on the spacers. In this case, the spacers can be configured to be outer ring spacers adjacent to the outer ring of the rolling bearing in the axial direction.

[0021] In the rolling bearing device according to the invention, the rolling bearing can be configured to be an angular contact ball bearing.

[0022] To solve the above-mentioned problems, the mechanical device according to the invention is configured to include a rotating shaft, a housing disposed on the outer circumference of the rotating shaft, and a rolling bearing device according to the invention that rotatably supports the rotating shaft with respect to the housing. In this case, the rotating shaft can be configured as a spindle device for a machine tool, which is the main spindle of a machine tool to which a cutting tool can be attached.

[0023] Because the mechanical device according to the invention is configured in this way, the rolling bearing device can be miniaturized, resulting in a smaller overall mechanical device, making it particularly suitable for use in high-speed rotation applications such as machine tool spindle devices.

[0024] Furthermore, in order to solve the above-mentioned other problems, the present invention provides a rolling bearing device comprising a rolling bearing having a plurality of rolling elements interposed between an inner ring and an outer ring, and a lubrication device attached to the rolling bearing to supply lubricant, wherein the lubrication device comprises a tank for holding lubricant, a positive displacement pump connected to the tank for discharging the supplied lubricant into the bearing space between the inner ring and the outer ring of the rolling bearing, a porous elastic body permeable to lubricant loaded in the casing of the positive displacement pump, an actuator for driving the positive displacement pump, a pressing body that presses a part or all of the porous elastic body permeated with lubricant within the casing with the driving force of the actuator to cause elastic deformation, and a power source unit and a control unit for the actuator.

[0025] As described above, the rolling bearing device of the present invention has a porous elastic material with lubricant permeability loaded inside the casing of a positive displacement pump that discharges lubricant into the bearing space between the inner and outer rings of the rolling bearing. Therefore, the lubricant supplied from the tank connection can be retained in a state where it has permeated into the pores of the porous elastic material by capillary action.

[0026] When the porous elastic body is pressed by a pressing body using the driving force of the actuator that drives the positive displacement pump, the lubricant held in this manner deforms so that part or all of the porous elastic body elastically shrinks, and an amount of lubricant corresponding to the amount of shrinkage seeps out of the porous elastic body and can be discharged from the casing of the positive displacement pump.

[0027] Lubricant that is not discharged but held in the porous elastic material is retained within the casing by capillary action, even if the casing is not necessarily sealed. Therefore, lubricant does not leak out of the pump even without the installation of on-off valves or check valves at the connection point between the casing and the tank, or at the nozzles and discharge ports leading from the casing to the bearing space.

[0028] Furthermore, the required amount of lubricant can be discharged from the positive displacement pump into the bearing space simply by controlling the pressing force of the porous elastic body by the actuator that drives the positive displacement pump. Moreover, the casing and tank of the positive displacement pump do not need to be equipped with pressure adjustment or airtight / liquid-tight structures such as on-off valves or check valves; these can be provided as needed.

[0029] In this way, the rolling bearing device of the present invention enables the stable and precise discharge of an appropriate amount of lubricant in the lubrication device using a simple mechanism.

[0030] Furthermore, in order to supply the lubricant held in the tank into the casing of the positive displacement pump as quickly and stably as possible, it is preferable that the porous elastic body extends from the casing of the positive displacement pump into the tank so that the lubricant permeability is continuous.

[0031] Furthermore, by loading the porous elastic material into the tank without any gaps, the lubricant is supplied from every corner of the tank into the casing of the positive displacement pump by capillary action, allowing for efficient and waste-free use of the lubricant in the tank of a predetermined capacity.

[0032] Furthermore, by using a composite material of multiple types of porous elastic materials with different elasticity and porosity as the porous elastic material, it is possible to adjust the supply speed of lubricant to the positive displacement pump, the amount of lubricating oil that evaporates over time, and the amount of lubricating oil that is discharged.

[0033] As the present invention is configured as described above, lubricating oil can be supplied efficiently and without waste from the lubricating oil supply mechanism by condition maintenance (CBM) according to the lubrication state of the rolling bearing, ensuring lubrication durability in grease lubrication. Furthermore, this makes it possible to miniaturize mechanical devices such as rolling bearing devices and machine tool spindle devices.

[0034] Furthermore, the present invention provides a pressure element that presses a porous elastic material permeable to lubricant, which is pressed by the driving force of an actuator to elastically deform the material, by loading the casing of a positive displacement pump, which is installed in the bearing space between the inner and outer rings of a rolling bearing to discharge lubricant, into the casing. This makes it easier for a lubrication device attached to the rolling bearing to temporarily hold the lubricant and discharge an appropriate amount of lubricant, and has the advantage that the appropriate amount of lubricant can be discharged from the lubrication device stably and as reliably as possible with a simple lubrication mechanism. It also has the advantage that the lubricant can be discharged in any direction regardless of the orientation of the device.

[0035] Vertical cross-sectional view of the rolling bearing device of the first embodiment Block diagram of the lubrication oil supply mechanism Flowchart showing the control of the lubrication oil supply mechanism Vertical cross-sectional view of the spindle device for a machine tool of the second embodiment Axial cross-sectional view of the main part of the rolling bearing device of the third embodiment Cross-sectional view along the line VI-VI in Figure 5 Block diagram illustrating the function of the lubrication device of the third embodiment Schematic cross-sectional view of the positive displacement pump illustrating the function of the porous elastic body of the third embodiment Schematic cross-sectional view of the positive displacement pump illustrating the function of the porous elastic body of the third embodiment Schematic cross-sectional view of the positive displacement pump illustrating the function of the porous elastic body of the third embodiment Schematic cross-sectional view of the positive displacement pump illustrating the function of the porous elastic body of the fourth embodiment Schematic cross-sectional view of the positive displacement pump illustrating the function of the porous elastic body of the fifth embodiment Schematic cross-sectional view of the positive displacement pump illustrating the function of the porous elastic body of the sixth embodiment

[0036] Embodiments of the present invention will be described below with reference to the drawings. The rolling bearing device of the first embodiment shown in Figures 1 to 3 comprises an angular contact ball bearing 10 as a rolling bearing and a lubrication oil supply mechanism 20 that supplies lubricating oil into the bearing space of the angular contact ball bearing 10, and is suitably used in mechanical devices used under particularly high-speed rotation conditions, such as machine tool spindle devices. Specifically, the high-speed rotation conditions referred to here are when the dn value is 70 × 10 ４ The above, preferably 110 × 10 ４ That concludes the explanation. There is no particular upper limit to the dn value, but for example, 200 × 10 ４ And, 180 x 10 ４ Therefore, the rolling bearing device of the first embodiment exhibits excellent lubrication durability even under such high-speed rotation conditions and can be used for a long period of time.

[0037] As shown in Figure 1, the angular contact ball bearing 10 comprises an inner ring 11 having a raceway surface 11a on its outer diameter surface, an outer ring 12 having a raceway surface 12a on its inner diameter surface, and balls 13 acting as rolling elements interposed between the opposing raceway surfaces 11a and 12a. The inner ring 11 and outer ring 12 are made of metal. The balls 13 are made of metal or ceramic.

[0038] As shown in Fig. 1, a plurality of balls 13 are held at regular intervals in the circumferential direction of the angular ball bearing 10 by a cage 14. Further, a grease composition 15 is enclosed in the bearing space formed between the inner ring 11 and the outer ring 12, and the angular ball bearing 10 is lubricated by being interposed between the raceway surfaces 11a, 12a and the balls 13. Note that the distribution of the grease composition 15 in Fig. 1 is merely an example and is not limited thereto.

[0039] Here, as shown in Fig. 1, the inner ring 11, the outer ring 12, and the balls 13 are in contact with each other at a predetermined angle θ, whereby the angular ball bearing 10 can support not only a radial load but also an axial load. One side of the raceway surface 11a of the inner ring 11 is a shoulder 11b. Further, the illustrated cage 14 is a so-called outer-ring-guided cage, and a guide surface 14a provided at an axial end of the outer diameter surface thereof is guided by the outer ring 12 by contacting the inner diameter surface of the outer ring 12.

[0040] As shown in Fig. 1, a seal member 16 is provided at one axial end of the bearing space in which the grease composition 15 is enclosed. The seal member 16 is adjacent to the shoulder 11b of the inner ring 11. Note that a mode in which the seal member 16 is not provided is also possible. At the other axial end of the bearing space, the seal member 16 is not provided and is open.

[0041] As shown in Fig. 1, the lubricating oil supply mechanism 20 is disposed adjacent to an end of the angular ball bearing 10 in the axial direction on the side where the seal member 16 is not provided. In the illustration, the lubricating oil supply mechanism 20 is incorporated in a spacer 30 abutted against the width surface of the angular ball bearing 10. Although not shown, the width surface of another angular ball bearing is abutted against the other end of the spacer 30, and the clearance and preload are adjusted by this spacer 30. The spacer 30 is made of a metal material.

[0042] As shown in FIG. 1, the spacer 30 is composed of an inner-ring spacer 31 that abuts against the width surface of the inner ring 11 of the angular ball bearing 10 and an outer-ring spacer 32 that abuts against the width surface of the outer ring 12. An annular casing 33 is fixed to the inner diameter surface of the outer-ring spacer 32. The casing 33 is composed of a casing main body 33a and a lid 33b. The side of the casing main body 33a facing the width surface of the angular ball bearing 10 is closed and the opposite side is open. The lid 33b detachably closes the opening of the casing main body 33a. The lubricating oil supply mechanism 20 is housed in the casing 33 fixed to the outer-ring spacer 32. By incorporating it into the outer-ring spacer 32, space saving is achieved.

[0043] FIG. 2 shows the lubricating oil supply mechanism 20 in a functional block diagram. As shown in the figure, the lubricating oil supply mechanism 20 includes a power supply unit 21, a control unit 22, a drive unit 23, a pump 24 as a supply unit for supplying lubricating oil, a tank 25 as a holding unit for holding lubricating oil, and a detection unit 26 for detecting the lubrication state of the angular ball bearing. Note that the arrangement of each element of the lubricating oil supply mechanism 20 is not limited to FIG. 2.

[0044] As shown in FIG. 2, the power supply unit 21 can supply power to the control unit 22 and the drive unit 23. The control unit 22 is composed of a microcomputer or the like and can transmit a command to the drive unit 23 according to the output of the detection unit 26. The drive unit 23 is a drive circuit for operating the pump 24.

[0045] As shown in FIG. 2, the pump 24 can suck the lubricating oil in the tank 25 and discharge a predetermined amount of lubricating oil toward the angular ball bearing 10. Here, the type of the pump 24 is not limited, and examples include a pneumatic or hydraulic-driven piston pump, a hydraulic pump such as a gear pump, and a diaphragm pump.

[0046] The detection unit 26 is capable of detecting and measuring lubrication characteristic values ​​(lubrication characteristic indices) that serve as indicators of the lubrication state of the angular contact ball bearing 10, such as the temperature, vibration, rotational torque, color of the grease composition 15, light transmittance / reflectance, odor, specific gravity, acid value, iron content, and moisture content. The installation location of the detection unit 26 is not limited and can be appropriately installed in accordance with the lubrication characteristic values ​​to be detected and measured. Figure 1 illustrates the installation inside and around the angular contact ball bearing 10.

[0047] As shown in Figure 2, the control unit 22 issues a command to the drive unit 23, which in turn operates the pump 24, and as shown in Figure 1, lubricating oil is supplied to the bearing space of the angular contact ball bearing 10 via a nozzle 27 protruding from the casing 33. As shown in the same figure, the tip of the nozzle 27 extends into the interior of the bearing space through the opening described above. For example, when the inner ring of the angular contact ball bearing 10 is rotating, the nozzle 27 discharges lubricating oil onto the outer diameter surface of the inner ring 11, including the raceway surface 11a, more specifically, near one side of the raceway surface 11a opposite to the shoulder portion 11b. The discharged lubricating oil moves to the raceway surface 11a due to centrifugal force and mixes with the grease composition 15 pre-sealed in the bearing space, improving the lubrication state of the angular contact ball bearing 10. The above is merely an example; the discharged lubricant only needs to reach the raceway surface, and the discharge point is not limited to the outer diameter surface including the raceway surface 11a of the inner ring 11, but may also be near the surface of the cage 14 or near the raceway surface 12a of the outer ring 12, for example.

[0048] As shown in Figure 2, the timing and amount of lubricating oil supplied from the lubricating oil supply mechanism 20 to the angular contact ball bearing 10 are controlled by the control unit 22 according to the output of the detection unit 26. As described above, the lubrication state of the angular contact ball bearing 10 is determined based on various lubrication characteristic values ​​detected and measured by the detection unit 26, namely the temperature, vibration, rotational torque of the angular contact ball bearing 10, the color of the grease composition 15, light transmittance / reflectance, odor, specific gravity, acid value, iron content, and moisture content. Based on this, the control unit 22 determines the amount and timing of lubrication. The type of detection unit 26 is not limited, but examples of various sensors and measuring instruments include temperature sensors, vibration sensors, rotation sensors, color sensors, optical sensors (light transmittance meters, light reflectance meters), odor sensors, specific gravity sensors, torque sensors, acid value meters, iron content meters, moisture content meters, etc.

[0049] Generally speaking, poor lubrication requires a large amount of lubricant per application and a short application interval, while good lubrication requires a small amount of lubricant per application and a longer application interval. However, the amount of lubricant supplied per application should preferably be a small amount that does not drastically affect the torque fluctuations of the angular contact ball bearing 10, and can be exemplified as about 0.001 mL to 0.1 mL. By supplying lubricant in the appropriate time and amount according to the lubrication state of the angular contact ball bearing 10, the grease lubrication state can be maintained in good condition, leading to long-term stabilization of its rolling characteristics and improvement of its lifespan. Because lubricant can be supplied efficiently, there is no need to store excess lubricant compared to supplying lubricant at regular intervals, allowing for a smaller tank 25 and a smaller lubricant supply mechanism 20. As a result, it does not require a large installation space and can be easily integrated into the spacer 30.

[0050] The detection unit 26 will be described in detail below. The temperature, vibration, and torque of the angular contact ball bearing 10 are lubrication characteristic values ​​that serve as indicators of the lubrication state of the bearing 10. As shown in Figure 2, the detection unit 26 includes a temperature sensor, a vibration sensor, and a rotation sensor. When an excessive load (excessive surface pressure) is applied to the angular contact ball bearing 10 or the lubrication state deteriorates, the contact ellipse of the rolling part becomes larger or metal contact increases, causing the bearing's temperature, vibration, and rotational torque to rise. Furthermore, deterioration of the lubrication state at the contact points between the balls 13 of the cage 14 and the raceway surfaces 11a and 12a also causes the temperature, vibration, and rotational torque of the angular contact ball bearing 10 to rise. Therefore, the detection unit 26 detects and measures the values ​​and changes in the temperature, vibration, and rotational torque of the angular contact ball bearing 10, and the control unit 22 determines the amount and timing of lubrication oil supply based on these values. In this respect, it is preferable to base the determination on the amount of change because it is more responsive. It is also possible to make a determination by combining values ​​and amounts of change.

[0051] Furthermore, lubrication characteristic values ​​that serve as indicators of the lubrication state of the angular contact ball bearing 10 include the color, light transmittance / reflectance, odor, specific gravity, acid value, iron content, and moisture content of the grease composition 15. As shown in Figure 2, the detection unit 26 includes a color sensor, optical sensors (light transmittance meter, light reflectance meter), odor sensor, specific gravity sensor, etc. (acid value meter, iron content meter, moisture content meter). A deficiency of lubricating oil on the raceway surfaces 11a and 12a of the angular contact ball bearing 10 is induced by the consumption or deterioration of the base oil in the grease composition 15 initially sealed in the bearing 10. For example, the heat generated by the rotation of the angular contact ball bearing 10, or heat transmitted from other heat sources around the bearing 10, such as the stator coil of a motor, can cause discoloration, changes in specific gravity due to oil separation, and an increase in acid value. Note that the change in hue varies depending on the type of grease composition.

[0052] Furthermore, wear particles generated in the rolling portion of the angular contact ball bearing 10 and in the contact area between the balls 13 of the cage 14 and the raceway surfaces 11a and 12a mix with the grease composition 15, causing discoloration of the grease composition 15, changes in light transmittance / reflectance, odor, specific gravity, and an increase in acid value and iron content. Generally, the discoloration of the grease composition 15 manifests as a change to a brownish or blackish hue. Alternatively, if moisture penetrates from the periphery into the interior of the angular contact ball bearing 10, moisture will be mixed into the grease composition 15. This reduces the lubrication performance of the grease composition, worsening the lubrication state of the angular contact ball bearing 10. Therefore, the detection unit 26 detects and measures the color, light transmittance / reflectance, odor, specific gravity, acid value, iron content, and moisture content of the grease composition 15, as well as their changes, and the control unit 22 determines the amount and timing of lubrication based on these values. In this respect, basing the decision on the amount of change is preferable because it offers greater responsiveness. It is also possible to make a decision by combining values ​​and amounts of change.

[0053] As a means of capturing changes in various elements that serve as indicators of lubrication status (temperature, vibration, and rotational torque of the angular contact ball bearing 10, and the color, light transmittance / reflectance, odor, specific gravity, acid value, iron content, and moisture content of the grease composition 15), for example, a set value (threshold) can be predetermined based on the relationship between multiple lubrication characteristic values ​​measured when the angular contact ball bearing 10 and the grease composition 15 are in a normal state. In this case, when the measurement value in the detection unit 26 exceeds that threshold, the control unit 22 sends a signal to the drive unit 23, and lubricating oil is supplied to the angular contact ball bearing 10. The measurement value and threshold here can include not only the lubrication characteristic value itself, but also the amount of change in the lubrication characteristic value. By combining multiple indicators and determining an abnormality when the amount of change in multiple lubrication characteristic values ​​exceeds the threshold, misjudgments are suppressed and reliability is increased.

[0054] The temperature, vibration, and rotational torque of the angular contact ball bearing 10 are preferable indicators in this case because they can be easily observed without disassembly during operation. Among these, rotational torque is more preferable as an indicator because it is directly related to the lubrication state. Furthermore, the color, light transmittance / reflectance, odor, specific gravity, acid value, iron content, and moisture content of the grease composition 15 can occur as precursors to changes in the lubrication state, and are therefore preferable indicators in this case because they allow for early prediction of changes in the lubrication state. For this reason, it is even more preferable to use a combination of the rotational torque of the angular contact ball bearing 10 and one of the characteristics of the grease composition 15 as indicators.

[0055] Figure 3 is a flowchart showing an example of lubricant supply control performed by the control unit 22. The processing in this flowchart is assumed to be performed at regular intervals. Referring to Figure 2, in step S1, the control unit 22 obtains lubrication characteristic values ​​from the detection unit 26. In this case, it is preferable that the values ​​are obtained from multiple detection units 26.

[0056] Next, in step S2, it is determined whether the lubrication characteristic value is greater than a threshold value pre-stored in the memory of the control unit 22. The threshold value is not particularly limited, but it may be determined by prior tests or simulations and may be manipulated or adjusted as appropriate by multiplying it by a coefficient. The memory can also store a table showing the relationships between multiple indicators, and the determination can be made based on that table.

[0057] If the lubrication characteristic value exceeds the threshold, in step S3, the control unit 22 supplies lubricating oil to the angular contact ball bearing 10 by driving the pump 24 for a predetermined time. After the predetermined time has elapsed, the pump 24 stops, and the process moves to step S4, then back to step S1. On the other hand, if the lubrication characteristic value falls below the threshold, the process in step S3 is not executed, and the process moves to step S4, then back to step S1.

[0058] The rolling bearing device of the first embodiment is used, for example, in the spindle device 1 for a machine tool of the second embodiment, as shown in Figure 4. As shown in the figure, the spindle device 1 for a machine tool includes a spindle 2 as a rotating shaft, a housing 3 consisting of an inner cylinder 3a and an outer cylinder 3b, and an angular contact ball bearing 10 that rotatably holds the spindle 2 relative to the inner cylinder 3a of the housing 3. A motor 4 is connected to one end of the spindle 2, and a cutting tool such as an end mill is connected to the other end. The motor 4 has a rotor 4a fixed to the outer circumference of the spindle 2 and a stator 4b fixed to the outer cylinder 3b, and rotates the spindle 2. The rolling bearing device of the first embodiment consists of this angular contact ball bearing 10 and a lubrication oil supply mechanism 20, and the angular contact ball bearing 10 is positioned by a spacer 30. The lubrication oil supply mechanism 20 is incorporated into the outer ring spacer 32 of the spacer 30 and supplies lubricating oil to the angular contact ball bearing 10.

[0059] The embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the invention is defined by the claims and includes all modifications within the meaning and scope of the claims.

[0060] In the above embodiment, an angular contact ball bearing 10 was exemplified as a rolling bearing, but the rolling bearing in the rolling bearing device of the present invention is not limited to this, and may be a deep groove ball bearing, cylindrical roller bearing, tapered roller bearing, self-aligning roller bearing, needle roller bearing, thrust cylindrical roller bearing, thrust tapered roller bearing, thrust needle roller bearing, thrust self-aligning roller bearing, etc. Furthermore, the structure of the angular contact ball bearing 10 is not limited to the above embodiment. For example, the structure of the cage 14 can be different from that of the above embodiment.

[0061] In the above embodiment, the lubrication oil supply mechanism 20 is incorporated into the outer ring spacer 32 of the spacer 30. However, the installation configuration of the lubrication oil supply mechanism 20 is not limited to this. It can also be incorporated into the inner ring spacer 31, or parts of the lubrication oil supply mechanism 20, such as a pump as the supply unit and a tank as the holding unit, may be placed inside a rolling bearing such as an angular contact ball bearing 10. Furthermore, the structure of the spacer 30, the structure of the casing 33, and the configuration of the lubrication oil supply mechanism 20 being incorporated into the outer ring spacer 32 are not limited to the above embodiment. In addition, in the above embodiment, the bearings 10 are arranged in a back-to-back configuration with the spacer 30 in between, but they may also be arranged in a front-to-back or parallel configuration, and the configuration is not limited.

[0062] The type of base oil in the grease composition sealed in the bearing space and the type of lubricant supplied from the lubricant supply mechanism are not particularly limited, but it is preferable that the lubricant supplied from the lubricant supply mechanism be the same as, or has a similar composition to, the base oil in the grease composition sealed in the bearing space, and that an oil with high affinity to the base oil or an oil with a kinematic viscosity close to that of the base oil is used.

[0063] In the above embodiment, a machine tool spindle device 1 was used as an example of a mechanical device, but the type of mechanical device is not limited to this, and the rolling bearing device according to the invention can be applied to mechanical devices other than machine tool spindle devices. Furthermore, the structure of the machine tool spindle device 1 is not limited to the above embodiment.

[0064] As shown in Figures 5 to 10, the third embodiment is a bearing device applicable to mechanical devices used in high-speed rotation such as machine tool spindles, and consists of an angular contact ball bearing A which has a cage 44 that holds the rolling elements 43, which are multiple balls, interposed between an inner ring 41 and an outer ring 42, so that the rolling elements 43 can rotate freely at regular intervals in the circumferential direction while being guided by the outer ring 42, and a lubrication device B which supplies lubricant O while being fixed in close contact with the axial end face of the outer ring 42.

[0065] As shown in Figures 5 and 6, the lubrication device B comprises a tank 45 for holding lubricant O and a positive displacement pump 46 for discharging the lubricant supplied from the tank 45 into the bearing space between the inner ring 41 and the outer ring 42. The pump 46 is incorporated between the outer ring spacer B1 and the inner ring spacer B2 and fixed to the outer ring spacer B1. The casing 48 of the positive displacement pump 46 is in communication with the tank 45 via a lubrication passage 47. The lubrication passage 47 may be molded together with the casing 48 or the tank 45.

[0066] The casing 48 is provided with a discharge nozzle 49 capable of discharging lubricating oil, and a porous elastic body 50 with lubricant permeability is loaded inside the casing 48. The porous elastic body 50 is loaded along the inner wall surface of the casing 48, and the portions where the oil supply passage 47 and the discharge nozzle 49 open to the inner wall surface are also covered with the porous elastic body 50.

[0067] Furthermore, as shown in Figures 5 to 8, the refueling device B includes an actuator 51 such as a piezoelectric element that drives a positive displacement pump 46, and a pressing body (= push head) 52 that operates with the driving force of the actuator, as well as a microcontroller or the like as the power source 53 and its control unit 54 for the actuator 51. The power supply mechanism of the power source 53 is arbitrary and may utilize, for example, a storage battery, a power supply connected to the outside of the refueling device B, or electromotive force obtained by building a power generation mechanism in the refueling device B.

[0068] The pressing body 52 is connected to or integrated with the actuator 51 to appropriately press the porous elastic body 50, and by being connected to or integrated with, for example, a diaphragm or a reciprocating piston, it can repeatedly perform the operation of contacting and pressing the porous elastic body 50, and then moving away from the porous elastic body 50.

[0069] In addition, the bearing space between the inner ring 41 and the outer ring 42, which are made of iron-based metal material, may be filled with the required amount of lubricating grease in the necessary places depending on the bearing application, and sealing members 55 may be attached to one or both axial ends of the bearing space, however, depending on the bearing application, it may not be necessary to fill it with lubricating grease.

[0070] As shown in Figures 6 and 7, a power source unit 53 using a power supply is connected to the control unit 54 and the actuator 51 so as to be able to supply power to them. The control unit 54, for example, uses a microcontroller and is connected so as to be able to send commands to the actuator 51.

[0071] When the actuator 51 operates the positive displacement pump 46 based on a command from the control unit 54, part or all of the porous elastic body 50 permeated with lubricant, which is loaded into the casing 48 of the positive displacement pump 46, is pressed and compressed by the press 52, or comes into contact with or separates from the press 52 without being subjected to the pressing force.

[0072] As shown in Figures 8 to 10, when the pressing body 52 presses the porous elastic body 50 containing the lubricant O, the pressing force pushes the lubricant O out of the porous elastic body 50, and the pushed-out liquid lubricant O is discharged into the bearing space from the tip of the discharge nozzle 49 which extends into the bearing space. Note that the discharge nozzle 49 may be configured in any shape as appropriate, rather than being a tube shape as shown in Figure 5.

[0073] For example, when the rolling bearing A is rotating its inner ring, liquid lubricant O is discharged from the tip of the discharge nozzle 49, moves along the raceway surface of the inner ring 41 (Figure 5) by centrifugal force from the outer circumferential surface of the inner ring 41, and lubricates the raceway surface of the outer ring 42 via the surface of the rolling elements 43.

[0074] The amount of liquid lubricant O discharged can be adjusted by the displacement of the pressing body 52 driven by the actuator 51, the pressing force, the pressing area and volume, the diameter and shape of the nozzle hole, and so on. The driving state of the actuator 51 is controlled by the control unit 54.

[0075] When the pressing body 52 is driven in the opposite direction to the pressing direction, the pressing force at the contact surface of the porous elastic body 50 with the pressing body 52 is reduced or becomes negative. Due to capillary action of the porous elastic body 50 or the pressure difference with the inside of the tank 5, the porous elastic body 50 swells while drawing in liquid lubricant O. At this time, air a may also be drawn into the porous elastic body 50, but the air a moves to the tank 45 via the lubrication passage 47 in a gas-liquid exchange. In the lubrication device B (Figure 5), these operations and actions are repeated to continuously or timely draw lubricant O from the tank 45 (Figure 9) and discharge it into the bearing space.

[0076] Furthermore, since the porous elastic body 50 is held in a state of being impregnated with lubricant by capillary force, it is possible to discharge the lubricant from the discharge nozzle 49 in any direction, for example, it is possible to discharge the lubricant in a direction opposite to gravity.

[0077] The actuator 51 described above can, for example, use a mechanism that combines a diaphragm or solenoid made of piezoelectric ceramic, a piston or plunger that reciprocates, and an electric motor. For relatively large rolling bearings, a fluid pressure cylinder powered by pneumatic or hydraulic pressure can also be used.

[0078] The positive displacement pump 46 only needs to have a pressing body 52, and may use a rotary pump as well as a reciprocating pump. The pressing body 52 installed in the chamber can also be operated by the fluid pressure generated by a gear pump or the like.

[0079] Specific examples of positive displacement pumps 46 include pneumatically or hydraulically driven piston pumps, hydraulic pumps such as gear pumps, and diaphragm pumps. Pumps using electric motors or piezoelectric elements, such as micropumps using piezoelectric ceramics, may also be used.

[0080] The porous elastic body 50 can be made of a material such as a nonwoven fabric with continuous gaps between densely packed fibers that draw in lubricant through capillary action, or a material that has the property of drawing it up into interconnected pores, like a sponge. Furthermore, the porous elastic body 50 is made of a material that is soft and porous enough to be elastically deformable when pressed by the driving force of the actuator 51, and can be made of a material that has interconnected pores and is elastically deformable, such as a soft elastic rubber (elastomer) foam. Typical examples of such materials include soft urethane foam, soft resin sponge, rubber sponge, felt, nonwoven fabric, and fiber filter material.

[0081] As a lubricant, liquid lubricating oil suitable for use with rolling bearings can be used at room temperature. However, lubricating grease containing thickeners that separates with external force or temperature rise, or waxes whose phase state changes from solid to liquid with temperature changes can also be used as lubricants.

[0082] The amount of lubricant, such as lubricating oil, discharged is preferably such that it does not affect the torque fluctuations of the rolling bearing, and may be an extremely small amount. For example, 0.001 mL to 0.1 mL can be discharged using a micropump or the like. The discharge amount may be controlled so that the amount and timing of lubrication are controlled according to the lubrication state of the rolling bearing A. The lubrication state may be detected by sensors installed inside or around the rolling bearing A, for example.

[0083] In Figures 5 and 6 illustrating the third embodiment, an angular contact ball bearing applicable to a machine tool spindle is shown as an example of rolling bearing A. However, the rolling bearing in the rolling bearing device of the present invention can also be a deep groove ball bearing, cylindrical roller bearing, tapered roller bearing, self-aligning roller bearing, needle roller bearing, thrust cylindrical roller bearing, thrust tapered roller bearing, thrust needle roller bearing, thrust self-aligning roller bearing, etc.

[0084] Furthermore, the rolling bearing device of the present invention is not limited to the illustrated configuration. For example, the tank 45 may be extended in a circular shape along the entire circumference of the outer ring spacer B1, the power source unit 53 and the control unit 54 may be arranged in any way within the space between the outer ring spacer B1 and the inner ring spacer B2, and the pump, tank, etc. that constitute the lubrication device B may be placed inside the rolling bearing. In addition, protective partitions may be provided to prevent contact between the power source unit 53 and the control unit 54, etc., and the inner ring spacer B2, or they may be covered with a casing.

[0085] Furthermore, the rolling bearing device of the present invention exhibits excellent lubrication durability even under high-speed rotation conditions, enabling long-term use. High-speed rotation conditions include, for example, a dn value of 70 × 10⁻⁶. ４ Preferably 110 x 10 ４ The above can be assumed. The upper limit of the dn value is not particularly limited, but for example, 200 × 10 ４ And, 180 x 10 ４ That is the case.

[0086] In the fourth embodiment shown in Figure 11, the porous elastic body 50 is extended and loaded so as to be continuous from inside the casing 48 into the tank 45, and the other main components are substantially the same as those of the third embodiment.

[0087] However, in the fourth embodiment, due to the gas-liquid exchange phenomenon that occurs after the discharge of the liquid lubricant O, air a that flows back from the discharge nozzle 49 tends to accumulate in the tank 45. Therefore, a vent hole 56 for releasing the air is provided in the tank 45 along with a check valve 57. The check valve 57 is preferably provided to avoid the risk of the lubricant O being pushed out by atmospheric pressure and leaking from the discharge nozzle 49 even when the pressing body 52 is not pressurizing the porous elastic body 50.

[0088] The fifth embodiment shown in Figure 12 is provided in which the porous elastic body 50 is installed not only in the casing 48 but also inside the tank 45 without any gaps, and the other main components are the same as in the third embodiment. The porous elastic body 50 can be installed inside the tank 45 by combining multiple pieces of the same or different materials, and each surface or part of them is configured to overlap or come into contact with one another.

[0089] When the porous elastic body 50 is loaded into the tank 45 without any gaps in this manner, the lubricant can permeate the porous elastic body 50 from every corner of the tank 45, and the lubricant in the tank 45 can be used without any waste.

[0090] Furthermore, if the inside of the tank 45 is completely filled with the porous elastic body 50, the lubricant is held in place by the capillary force of the porous elastic body 50, and when the lubricant is discharged from the discharge nozzle 49, gas-liquid exchange occurs within the porous elastic body 50. Therefore, a vent hole may be provided in the tank 45 to promote the movement of gas and liquid. Also, as in the fourth embodiment, a vent hole may be combined with a check valve.

[0091] The sixth embodiment shown in Figure 13 is an example in which the porous elastic body 50 is a composite material made by combining porous elastic bodies 50, 50a, and 50b of multiple types of materials with different properties such as elasticity and porosity, and the other main components are the same as in the first embodiment.

[0092] When combining multiple porous elastic bodies 50, 50a, and 50b, it is possible to combine materials with different elasticity, porosity, and other properties, i.e., different compositions and densities. In this way, the supply rate of lubricant to the positive displacement pump 46, the amount of lubricant that evaporates over time, and the amount of lubricant discharged can be adjusted.

[0093] For example, if porous elastic bodies 50a and 50b made of foam having communicating pores are placed in the tank 45, and a porous elastic body 50 made of a fibrous molded body is placed in the casing 48 of the pump 46, the amount of lubricant discharged can be adjusted by slowing down the movement of the lubricant with the porous elastic bodies 50a and 50b made of foam with a low porosity, while drawing out a sufficient or appropriate amount of lubricating oil from the porous elastic body 50 made of a fibrous molded body. In addition, vents may be provided in the tank 45, and as in the fourth embodiment, vents and check valves may be combined in the tank 45.

[0094] As described in the third to sixth embodiments of the present invention, since the lubricant O is discharged into the rolling bearing A via the porous elastic body 50, the lubricant does not leak out to the outside even without providing on-off valves or check valves at the connection between the casing 48 and the tank 45, or at the discharge nozzle 49 or oil supply passage 47 leading from the casing 48 to the bearing space.

[0095] Furthermore, malfunctions caused by insufficient airtightness in the pump mechanism are less likely to occur, air-only discharge (so-called "dry firing") can be prevented, and the amount of lubricant discharged can be adjusted by the arrangement and combination of the porous elastic body 50. Moreover, it is sufficient for the lubricant to be temporarily held in the porous elastic body 50 during the discharge operation, and since the lubricant can be discharged in a direction against gravity, the lubricant can be discharged in any direction regardless of the orientation of the device. Therefore, the appropriate amount of lubricant discharged in the lubrication device B can be achieved as reliably as possible with a simple lubrication mechanism.

[0096] The base oil of the lubricating grease sealed in the bearing space and the lubricant supplied from the tank are not particularly limited, but it is preferable that the lubricant supplied from the tank be the same as, or has a similar composition to, the base oil of the lubricating grease sealed in the bearing space, and that use an oil type that has high affinity with the base oil or an oil with a kinematic viscosity close to that of the base oil.

[0097] 1 Spindle device for machine tool 2 Spindle 3 Housing 3a Inner cylinder 3b Outer cylinder 4 Motor 4a Rotor 4b Stator 10 Angular contact ball bearing 11 Inner ring 11a Raceway surface 11b Shoulder 12 Outer ring 12a Raceway surface 13 Ball 14 Cage 14a Guide surface 15 Grease composition 16 Seal member 20 Lubrication oil supply mechanism 21 Power supply unit 22 Control unit 23 Drive unit 24 Pump 25 Tank 26 Detection unit 27 Nozzle 30 Spacer 31 Inner ring spacer 32 Outer ring spacer 33 Casing 33a Casing body 33b Cover 41 Inner ring 42 Outer ring 43 Rolling element 44 Cage 45 Tank 46 Positive displacement pump 47 48 Lubrication passage 49 Casing 49 Discharge nozzles 50, 50a, 50b Porous elastic body 51 Actuator 52 Pressing body 53 Power source unit 54 Control unit 55 Seal member 56 Ventilation hole 57 Check valve A Rolling bearing B Lubrication device B1 Outer ring spacer B2 Inner ring spacer O Lubricant a Air

Claims

1. A rolling bearing device comprising a rolling bearing and a lubricating oil supply mechanism, wherein the rolling bearing comprises an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a grease composition sealed in the bearing space between the inner ring and the outer ring, and the lubricating oil supply mechanism comprises a holding part for holding lubricating oil, a supply part for supplying the lubricating oil held in the holding part to the bearing space of the rolling bearing, a detection part for detecting lubrication characteristic values ​​related to the lubrication state of the rolling bearing, and a control unit for controlling the operation of the supply unit, wherein the control unit is configured to determine the amount of oil supplied from the supply unit and the timing of oil supply according to the output of the detection unit.

2. The rolling bearing device according to claim 1, wherein the detection unit detects, as the lubrication characteristic value, at least one of the following: the temperature, vibration, and rotational torque of the rolling bearing, and the color, light transmittance / reflectance, odor, specific gravity, acid value, iron content, and moisture content of the grease composition.

3. The rolling bearing device according to claim 2, wherein the detection unit detects a plurality of lubrication characteristic values ​​from among the lubrication characteristic values, and the control unit drives the supply unit to supply lubricating oil to the bearing space when the amount of change of two or more of the lubrication characteristic values ​​exceeds a predetermined set value.

4. The rolling bearing device according to claim 2, wherein the detection unit detects a plurality of lubrication characteristic values ​​from among the lubrication characteristic values, and the control unit drives the supply unit to supply lubricating oil to the bearing space when two or more of the lubrication characteristic values ​​exceed a predetermined set value.

5. The rolling bearing device according to claim 3 or 4, wherein the predetermined set value is determined based on the relationship between a plurality of lubrication characteristic values ​​measured when the rolling bearing and the grease composition are in a normal state.

6. The rolling bearing device according to claim 5, wherein one of the plurality of lubrication characteristic values ​​is the rotational torque of the rolling bearing.

7. The rolling bearing device according to claim 1 or claim 2, further comprising spacers adjacent to the rolling bearing in the axial direction, wherein the lubrication oil supply mechanism is mounted on the spacers.

8. The rolling bearing device according to claim 7, wherein the spacer is an outer ring spacer adjacent to the outer ring of the rolling bearing in the axial direction.

9. The rolling bearing device according to claim 1 or claim 2, wherein the rolling bearing is an angular contact ball bearing.

10. A mechanical device comprising: a rotating shaft; a housing disposed on the outer circumference of the rotating shaft; and a rolling bearing device according to claim 1 or 2 that rotatably supports the rotating shaft with respect to the housing.

11. The spindle device for a machine tool according to claim 10, wherein the rotating shaft is the spindle of a machine tool to which a cutting tool can be attached.

12. A rolling bearing device comprising a rolling bearing having a plurality of rolling elements interposed between an inner ring and an outer ring, and a lubrication device attached to the rolling bearing for supplying lubricant, wherein the lubrication device comprises a tank for holding lubricant, a positive displacement pump for discharging the lubricant supplied from the tank into the bearing space between the inner ring and the outer ring of the rolling bearing, a porous elastic body permeable to lubricant loaded in the casing of the positive displacement pump, an actuator for driving the positive displacement pump, a pressing body for elastically deforming a part or all of the porous elastic body permeated with lubricant within the casing by the driving force of the actuator, and a power source unit and a control unit for the actuator.

13. The rolling bearing device according to claim 12, wherein the casing of the positive displacement pump is a casing that communicates with the tank and the oil supply passage.

14. The rolling bearing device according to claim 13, wherein the porous elastic body is a porous elastic body loaded so as to be continuous from inside the casing into the tank.

15. The rolling bearing device according to claim 14, wherein the porous elastic body is a porous elastic body packed without any gaps inside the tank.

16. The rolling bearing device according to any one of claims 12 to 15, wherein the porous elastic body is a composite of multiple types of porous elastic bodies having different elastic forces and porosity.

Images