Machine tool spindle unit

Abstract

The present invention provides a spindle device for a machine tool that prevents lubricating oil from adhering to the area around the bearing and prevents the bearing temperature from rising due to the re-inflow of lubricating oil. [Solution] An air supply passage 34 is provided radially through the outer ring collar 31, which has a notch 33 that forms part of the oil drain passage 29. An air introduction passage 35 is provided in the fixed housing 2 to supply air to the air supply passage 34 of the outer ring collar 31. The inner ring collar 32 consists of a first ring portion 41 that faces the inner surface of the outer ring collar 31 from the radially inward side with a required gap between them, and a second ring portion 42 positioned between the first ring portion 41 and the inner ring 4b. The outer diameter of the second ring portion 42 is larger than the inner diameter of the outer ring collar 31, so that a gap G is formed between the outer ring collar 31 and the second ring portion 42, which serves as a guide passage 36 that guides the air blown out from the air supply passage 34 of the outer ring collar 31 to the oil drain passage 29.

Description

Technical Field

[0001] This invention relates to a spindle device of a machine tool, in which lubrication of a bearing that rotatably supports a spindle with respect to a fixed housing is performed by feeding oil-air from one side surface through an oil supply passage into the bearing and discharging the oil-air used for lubricating the bearing from the other side surface of the bearing through an oil discharge passage.

Background Art

[0002] In this specification, “oil-air” is expressed to include both oil mist and oil-air. More specifically, in oil-air lubrication, compressed air is supplied into a lubrication pipe, and a fixed amount of lubricating oil is periodically discharged into the compressed air in the pipe by a mixing valve to mix the lubricating oil with the air and convey it, and it is supplied to the bearing through a nozzle. In oil mist lubrication, atomized lubricating oil is conveyed by compressed air and supplied to the bearing through a nozzle.

[0003] For example, in a spindle device of a machine tool having a vertical spindle, conventionally, the spindle is rotatably supported inside a fixed housing through a plurality of rolling bearings, and an oil supply passage is formed from the fixed housing to a collar on the outer ring side of the bearing, with one end opening to face one side surface of each bearing. Similarly, an oil discharge passage is formed in the fixed housing, with one end opening to the other side surface side of each bearing on the inner peripheral surface of the fixed housing (see Patent Document 1).

[0004] And the lubrication of the bearing that rotatably supports the spindle with respect to the fixed housing is performed as follows. That is, oil-air is fed into the bearing from one side surface through the oil supply passage, and the oil-air used for lubricating the bearing is discharged from the other side surface of the bearing through the oil discharge passage, thereby lubricating the bearing.

[0005] An example of the conventional spindle device as described above is shown in FIG. 3. Note that FIG. 3 is shown for convenience such that the oil supply passage and the oil discharge passage are in the same position in the circumferential direction, different from the actual positions.

[0006] In Figure 3, a vertical hollow main shaft (2) is positioned inside a fixed housing (1), and the lower part of the main shaft (2) is rotatably supported at two points spaced apart vertically by two parallel-arranged angular contact ball bearings (3), (4), (5), and (6). The two upper angular contact ball bearings (3) and (4) are arranged in parallel with the backs of their outer rings (3a) and (4a) facing downwards, while the two lower angular contact ball bearings (5) and (6) are arranged in parallel with the fronts of their outer rings (5a) and (6a) facing downwards. These angular contact ball bearings (3) to (6) are designed to withstand radial loads and thrust loads in two directions.

[0007] The outer rings (3a) to (6a) of all angular contact ball bearings (3) to (6) are sandwiched between a stepped portion (1a) formed on the inner circumferential surface of the fixed housing (1) and a cover (7) fixed to the lower end of the fixed housing (1), with outer ring collars (8), (9), and (10) interposed between adjacent outer rings (3a) to (6a). The inner circumferential surface of the fixed housing (1) is provided with a small diameter portion (1b) for forming the stepped portion (1a). The cover (7) has a cylindrical portion (7a) integrally formed into it, which is fitted into the fixed housing (1), and a notch (7b) is formed in this cylindrical portion (7a) from its upper end. The inner rings (3b), (4b), (5b), and (6b) of all angular contact ball bearings (3) to (6) are sandwiched between a stepped portion (2a) formed on the outer circumference of the main shaft (2) and a nut (11) screwed onto the lower end of the main shaft (2). Inner ring collars (12), (13), (14), and (15) are interposed between adjacent inner rings (3b) to (6b) and between the uppermost inner ring (3b) and the stepped portion (2a), respectively.

[0008] A thick inward-facing flange (16) is integrally formed on the upper part of the inner circumferential surface of the outer ring collar (8) positioned between the outer rings (3a) and (4a) of the two upper angular contact ball bearings (3) and (4). Furthermore, the outer diameter of the outer circumferential surface of the lower half of the outer ring collar (8) is smaller than the outer diameter of the outer circumferential surface of the upper half, and one (or more) notches (18) are formed in the lower half of the outer ring collar (8) from its lower end. The outer ring collar (8) has a substantially L-shaped through hole (19) that extends from the outer circumferential surface of the upper half toward the radially inner end of the inward-facing flange (16), with its tip bending upward and opening onto the upper surface of the inward-facing flange (16).

[0009] The outer ring collar (10) positioned between the outer rings (5a) and (6a) of the two lower angular contact ball bearings (5) and (6) is vertically symmetrical to the collar (8) positioned between the outer rings (3a) and (4a) of the two upper angular contact ball bearings (3) and (4) of the upper parts. The outer ring collar (9) positioned between the outer ring (4a) of the second-to-last angular contact ball bearing (4) and the outer ring (5a) of the second-to-last angular contact ball bearing (5) has thick inward-facing flanges (20) integrally formed at both the upper and lower ends of its inner circumferential surface. The outer ring collar (9) has a substantially L-shaped through hole (21) that extends from the upper end of its outer circumference toward the radially inner end of the upper inward flange (20), bends upward, and opens onto the upper surface of the inward flange (20). Additionally, a substantially L-shaped through hole (22) is formed that extends from the lower end of its outer circumference toward the radially inner end of the lower inward flange (20), bends downward, and opens onto the lower surface of the inward flange (20).

[0010] An outward-facing flange (23) is integrally formed on the inner ring collar (15) positioned between the stepped portion (2a) of the main shaft (2) and the inner ring (3b) of the uppermost angular contact ball bearing (3).

[0011] Linear through holes (24A), (24B), (24C), and (24D) extending radially inward from their outer circumferential surfaces are formed on the left side of the fixed housing (1) at a height slightly below the two upper angular contact ball bearings (3) and (4), and at a height slightly above the two lower angular contact ball bearings (5) and (6). These through holes (24A) to (24D) lead to through holes (19), (21), and (22) in the outer ring collars (8) to (10), respectively. An oil supply passage (25) is formed by the through holes (24A) to (24D) of the fixed housing (1) and the through holes (19), (21), and (22) of the outer ring collars (8) to (10).

[0012] A short, straight, lateral through-hole (26) is formed in the right portion of the fixed housing (1) at a height slightly below the lowest angular contact ball bearing (6) and corresponding to the notch (7b) of the cover (7), extending radially inward from its outer surface. Additionally, a straight, vertical hole (27) is formed in the right portion of the fixed housing (1), extending upward from the inner surface of the lateral through-hole (26) and reaching the small diameter portion (1b) of the fixed housing (1). Furthermore, short, straight, lateral through-holes (28A), (28B), and (28C) extending radially inward from the inner surface of the vertical hole (27) are formed at a height slightly above the uppermost angular contact ball bearing (3) on the right side of the fixed housing (1), and at heights corresponding to the notches (18) in the outer ring collar (8) between the two upper angular contact ball bearings (3) and (4) and the outer ring collar (10) between the two lower angular contact ball bearings (5) and (6). These holes (26), (27), (28A), (28B), and (28C) form an oil drain passage (29).

[0013] In a spindle device with this configuration, when the spindle (2) rotates, lubricating oil air is sent into each oil supply passage (25) and discharged from the radial inner end openings of the through holes (19), (21), and (22) of each outer ring collar (8) to (10) toward the angular contact ball bearings (3) to (6). At this time, oil air discharged from the through holes (19), (21), and (22) of the outer ring collars (8) to (10) is sent into each oil supply passage (25) to ensure that the oil air discharged from the through holes (19), (21), and (22) of the outer ring collars (8) to (10) reaches the angular contact ball bearings (3) to (6) in advance. In this way, each angular contact ball bearing (3) to (6) is lubricated.

[0014] Here, since the drain passage (29) is open to the atmosphere, the pressure inside is approximately equal to atmospheric pressure and is lower than the pressure on the supply side. Therefore, the oil air supplied from one side of the angular contact ball bearings (3) to (6) escapes to the other side, enters the drain passage (29) directly through the radial inner end opening of the transverse through hole (28A), enters the drain passage (29) through the radial inner end opening of the transverse through hole (26) via the notch (7b), enters the drain passage (29) through the radial inner end openings of the transverse through holes (28B) and (28C) via the notch (18) and gap (17) (see Figure 4), and is discharged into the atmosphere through the drain passage (29).

[0015] According to the spindle device shown in Figure 3, oil-air (lubricating oil transported by air) is supplied to the bearings (3) to (6) from one side through the oil supply passage (25), and the oil-air used for lubrication is discharged from the other side of the bearings (3) to (6) through the oil discharge passage (29), thereby lubricating the bearings (3) to (6). This allows the lubricating oil used to lubricate the bearings (3) to (6) to be discharged quickly.

[0016] Figure 4 shows the main part of a conventional spindle device that is the subject of the present invention (the part on the side of the lubricating oil drainage passage).

[0017] In Figure 4, the main shaft (2) is rotatably supported inside the fixed housing (1) via a bearing (4). The bearing (4) consists of an outer ring (4a), an inner ring (4b), and balls (rolling elements) (4c). The outer ring (4a) is held in place by an outer ring collar (8), and the inner ring (4b) is held in place by an inner ring collar (12). Lubrication of the bearing (4) is performed by supplying oil-air to the bearing (4) from one side through an oil supply passage (25) (see Figure 3), and discharging the oil-air used for lubrication of the bearing (4) through an oil discharge passage (29) from the other side of the bearing (4) (the part shown in Figure 4). The outer ring collar (8) has a notch (18) in the part that contacts the outer ring (4a), and the oil-air that flows into the bearing (4) flows out through this notch (18) into the oil discharge passage (29).

[0018] In the spindle assembly of a machine tool, lubrication is performed by supplying lubricating oil to the bearings as oil-air, as described above. However, if the supplied lubricating oil is not properly discharged and remains accumulated around the bearings and collars, the accumulated lubricating oil will re-flow into the bearings, resulting in an over-oil condition and causing the bearings to overheat. When the bearing temperature rises, the spindle may deform due to thermal displacement, which can affect the machining accuracy of the machine tool. [Prior art documents] [Patent Documents]

[0019] [Patent Document 1] Japanese Patent Publication No. 2002-361540 [Overview of the project] [Problems that the invention aims to solve]

[0020] In Figure 4, since the outer ring collar (8) does not rotate, some of the lubricating oil adheres to the end face of the outer ring collar (8) indicated by A. This adhered lubricating oil may suddenly re-flow into the bearing (4), which can affect the machining accuracy of the machine tool.

[0021] The object of this invention is to solve the above problems and provide a spindle device for a machine tool that can prevent lubricating oil from adhering to the area around the bearing and prevent the bearing temperature from rising due to the re-inflow of lubricating oil. [Means for solving the problem]

[0022] To achieve the above objective, the present invention comprises the following embodiments.

[0023] 1) In a spindle device of a machine tool, the lubrication of multiple bearings that rotatably support the spindle relative to a fixed housing is performed by supplying oil-air to the bearings from one side through an oil supply passage, and discharging the oil-air used for lubricating the bearings from the other side through an oil discharge passage, and the spindle device is provided with multiple outer ring collars that hold the outer rings of multiple bearings and multiple inner ring collars that hold the inner rings of multiple bearings, and the required outer ring collars are provided with through holes that form part of the oil supply passage and notches that form part of the oil discharge passage, The outer ring collar, which has a notch that forms part of the oil drain passage, is provided with an air supply passage located near the notch and extending radially through it, and the fixed housing is provided with an air inlet passage that supplies air to the air supply passage of the outer ring collar from the fixed housing side. The spindle device of a machine tool is characterized in that the inner ring collar comprises a first ring portion whose outer circumferential surface faces the inner circumferential surface of the outer ring collar from the radially inward side with a required gap between them, and a second ring portion positioned between the first ring portion and the inner ring, wherein the outer diameter of the second ring portion is larger than the inner diameter of the outer ring collar, so that a gap is formed between the end face of the outer ring collar on the side closer to the bearing and the end face of the opposing second ring portion on the side further from the bearing, which serves as a guide passage for guiding air blown out from the air supply passage of the outer ring collar to the oil discharge passage.

[0024] 2) Lubrication of a plurality of bearings that rotatably support the main shaft with respect to the fixed housing is performed by feeding oil-air from one side surface side to the bearings through an oil supply passage and discharging the oil-air used for lubricating the bearings from the other side surface side of the bearings through an oil discharge passage. A plurality of outer ring collars that suppress the outer rings of the plurality of bearings and a plurality of inner ring collars that suppress the inner rings of the plurality of bearings are provided. The outer ring of the bearing located at the end of the plurality of bearings abuts against a small-diameter portion provided in the fixed housing without passing through the outer ring collar. In the main shaft device of a machine tool, a lateral hole that constitutes a part of the oil discharge passage is provided in the small-diameter portion of the fixed housing and communicates with a linear vertical hole provided in the fixed housing. The small-diameter portion of the fixed housing consists of an outer ring abutting portion provided with a lateral hole that constitutes a part of the oil discharge passage and suppresses the outer ring of the bearing, and an inner ring collar opposing portion having an inner diameter smaller than the inner diameter of the outer ring abutting portion. An air supply passage is provided in the fixed housing, which consists of an inner penetrating passage that penetrates the inner ring collar opposing portion of the small-diameter portion and an outer penetrating passage that continues from the inner penetrating passage and penetrates the outer portion of the fixed housing. The inner ring collar consists of a first ring portion whose outer peripheral surface faces radially inward with a required gap from the inner peripheral surface of the inner ring collar opposing portion of the small-diameter portion of the fixed housing, and a second ring portion disposed between the first ring portion and the inner ring. The outer diameter of the second ring portion is made larger than the inner diameter of the inner ring collar opposing portion of the small-diameter portion of the fixed housing, so that a gap serving as a guide passage for guiding the air blown out from the air supply passage to the oil discharge passage is formed between the end surface of the inner ring collar opposing portion of the small-diameter portion of the fixed housing closer to the bearing and the end surface of the second ring portion facing it farther from the bearing. The main shaft device of a machine tool is characterized by this.

[0025] 3) The outer peripheral surface of the second ring portion of the inner ring collar is a tapered surface whose outer diameter increases from the side closer to the bearing to the side farther from the bearing. The main shaft device of the machine tool according to 1) or 2) above is characterized by this.

Advantages of the Invention

[0026] According to the spindle device of the machine tool described in 1) above, the air supplied to the air supply passage of the outer ring collar strikes the outer surface of the inner ring collar and changes direction, and a portion of it flows into the oil drain passage through the gap (guide passage) formed between the outer ring collar and the second ring portion of the inner ring collar, so that the lubricating oil adhering to the end face of the outer ring collar on the side closer to the bearing is discharged from the oil drain passage along with the air. Therefore, since the lubricating oil is unlikely to remain attached to the outer ring collar, which is the fixed side, and thus is likely to re-enter the bearing, the adhesion of lubricating oil to the collar is eliminated. This prevents the bearing temperature from rising, and the problem of the spindle deforming and affecting the machining accuracy of the machine tool is resolved.

[0027] According to the spindle device of the machine tool described in 2) above, even if the outer ring of the bearing is in contact with a small diameter portion provided on the fixed housing without an outer ring collar, the same effect as the spindle device of the machine tool described in 1) above can be obtained.

[0028] According to the spindle device of the machine tool described in 3) above, the lubricating oil adhering to the inner ring collar is carried by centrifugal force to the end of the guide path and flows into the drain passage, so the lubricating oil adhering to the end face of the inner ring collar on the side closer to the bearing is discharged from the drain passage along with air. Therefore, since the lubricating oil adhering to the inner ring collar does not re-flow into the bearing, the bearing temperature rise can be prevented, and the problem of the spindle deforming and affecting the machining accuracy of the machine tool is resolved. [Brief explanation of the drawing]

[0029] [Figure 1] Figure 1 is a longitudinal cross-sectional view of the main part showing a first embodiment of the spindle device of a machine tool according to this invention. [Figure 2] Figure 2 is a longitudinal cross-sectional view of the main part showing a second embodiment of the spindle device of the machine tool of this invention. [Figure 3] Figure 3 is a longitudinal cross-sectional view showing the entire spindle assembly of a conventional machine tool. [Figure 4] Figure 4 is a longitudinal cross-sectional view of the main part of a conventional machine tool spindle assembly, corresponding to Figures 1 and 2. [Modes for carrying out the invention]

[0030] A first embodiment of the spindle device of the machine tool of this invention will be described below with reference to Figure 1.

[0031] The spindle assembly of the first embodiment of this invention, shown in Figure 1, is intended to solve the problems of the conventional spindle assembly of a machine tool shown in Figures 3 and 4. With the same configuration as the conventional one, the spindle (2) is rotatably supported inside a fixed housing (1) via a bearing (4). The bearing (4) consists of an outer ring (4a), an inner ring (4b), and balls (rolling elements) (4c). The outer ring (4a) is held in place by an outer ring collar (31), and the inner ring (4b) is held in place by an inner ring collar (32). Oil air that flows into the bearing (4) flows out into the oil drain passage (29) through a notch (33) provided in the outer ring collar (31).

[0032] The spindle assembly of this embodiment of the machine tool has a configuration different from the conventional one, in which an air supply passage (34) is provided in the outer ring collar (31) that penetrates radially, adjacent to a notch (33) above and below, and an air introduction passage (35) is provided in the fixed housing (1) for introducing air into the air supply passage (34) of the outer ring collar (31). The inner ring collar (32) consists of a first ring portion (41) whose outer circumferential surface (41a) faces the inner circumferential surface (31a) of the outer ring collar (31) from the radially inward side with a required gap, and a second ring portion (42) positioned between the first ring portion (41) and the inner ring (4b).

[0033] The outer diameter of the second ring portion (42) is larger than the inner diameter of the outer ring collar (31), thereby forming a gap (G) between the end face (31b) of the outer ring collar (31) on the side closer to the bearing (4) and the opposite end face (42a) of the second ring portion (42) on the side further from the bearing (4). The gap (G) extends radially outward from the inner circumferential surface (31a) of the outer ring collar (31) toward the notch (33) provided in the outer ring collar (31), and serves as a guide passage (36) that guides the air blown out from the air supply passage (34) of the outer ring collar (31) toward the oil drain passage (29). Air blown out from the air supply passage (34) of the outer ring collar (31) strikes the outer circumferential surface (41a) of the first ring portion (41) of the inner ring collar (32), changing direction, and a portion of it flows through the guide passage (36) and into the oil drain passage (29) via the notch (33) provided in the outer ring collar (31). At this time, lubricating oil adhering to the end face (31b) of the outer ring collar (31) on the side closer to the bearing (4) is carried along with the air and discharged from the oil drain passage (29).

[0034] The outer circumferential surface (42b) of the second ring portion (42) of the inner ring collar (32) is a tapered surface in which the outer diameter increases from the side closer to the bearing (4) to the side further away. As the inner ring collar (32) rotates with the rotation of the main shaft (2), centrifugal force acts on the lubricating oil adhering to the inner ring collar (32). Here, since the outer circumferential surface (42b) of the second ring portion (42) of the inner ring collar (32) is a tapered surface in which the outer diameter increases from the side closer to the bearing (4) to the side further away, the lubricating oil adhering to the second ring portion (42) of the inner ring collar (32) is sent radially outward along the tapered surface (i.e., away from the bearing (4)), reaches the radially outer end of the guide passage (36), and flows into the drain passage (29) through the notch (33) provided in the outer ring collar (31), accompanied by the air passing through the guide passage (36).

[0035] According to the spindle device of the machine tool of the above embodiment, the air supplied to the air supply passage (34) of the outer ring collar (31) causes the lubricating oil adhering to the end face (31b) of the outer ring collar (31) on the side closer to the bearing (4) to be discharged from the oil discharge passage (29). As a result, the adhesion of lubricating oil to the area around the outer ring collar (31), which is the fixed side and therefore likely to remain adhering to it and re-flow into the bearing (4), is eliminated. This prevents the temperature of the bearing (4) from rising and eliminates the problem of the spindle (2) deforming and affecting the machining accuracy of the machine tool.

[0036] Furthermore, because the outer circumferential surface (42b) of the second ring portion (42) of the inner ring collar (32) is a tapered surface in which the outer diameter increases from the side closer to the bearing (4) to the side further away, lubricating oil is prevented from flowing back into the bearing (4) on the inner ring collar (32) side as well, thereby more reliably resolving the problem of affecting the machining accuracy of the machine tool.

[0037] Although the first embodiment described above was explained as a configuration that replaces the outer ring collar (8) and inner ring collar (12) in the conventional configuration shown in Figure 4, the same effect can be obtained for the other outer ring collar (10) and inner ring collar (14) shown in Figure 3 by using the same configuration as the first embodiment, in which an air supply passage (34) for supplying air to the outer ring collar (31) side is added, and a second ring portion (42) for guiding air to the oil drain passage (29) is added to the inner ring collar (32) side.

[0038] The spindle assembly of a machine tool to which the above-described first embodiment can be applied is not limited to the configuration shown in Figure 3. The number of bearings, the number of outer ring collars, and the number of inner ring collars are not particularly limited. The outer ring collar, which has through holes forming part of the oil supply passage and notches forming part of the oil drain passage, may be one or multiple (including all of them). Furthermore, the first ring portion (41) and the second ring portion (42) may be separate components or may be formed integrally.

[0039] In Figure 3, the outer ring (3a) of bearing (3), which is located at the upper end of the multiple bearings (3) to (6), is in contact with a stepped portion (1a) formed by a small-diameter portion (1b) provided in the fixed housing (1). The small-diameter portion (1b) of the fixed housing (1) is provided with a horizontal hole (28A) that connects to a straight vertical hole (27) provided in the fixed housing (1) and forms part of the drain passage (29).

[0040] A preferred form of the above configuration (a configuration in which the outer ring (3a) is held in place by a small-diameter portion (1b) provided on the fixed housing (1) without going through the outer ring collar (31)) (a second embodiment of the spindle device of the machine tool of this invention) will be described with reference to Figure 2.

[0041] In Figure 2, the main shaft (2) is rotatably supported inside the fixed housing (1) via a bearing (3), with the same configuration as in the conventional design. The bearing (3) is located at the upper end of multiple bearings and consists of an outer ring (3a), an inner ring (3b), and balls (rolling elements) (3c). The outer ring (3a) is held in place by the small diameter portion (51) of the fixed housing (1), and the inner ring (3b) is held in place by the inner ring collar (32). Oil air that flows into the bearing (3) flows out into the oil drain passage (29) via a lateral hole (28A) provided in the small diameter portion (51).

[0042] The spindle assembly of the machine tool in the second embodiment has a configuration different from the conventional and first embodiments, in which the small diameter portion (51) of the fixed housing (1) is made such that the outer ring collar (31) shown in Figure 1 is integrated with the conventional small diameter portion (1b) (see Figure 3). That is, the small diameter portion (51) of the fixed housing (1) consists of an outer ring contact portion (52) which is provided with a lateral hole (28A) that forms part of the oil drain passage (29) and holds down the outer ring (3a) of the bearing (3), and an inner ring collar opposing portion (53) which is integrally provided with the outer ring contact portion (52) and faces the first ring portion (41) of the inner ring collar (32). Furthermore, the air supply passage (54) for supplying air consists of an inner supply passage (54a) that penetrates the inner ring collar opposing portion (53) of the small diameter portion (51) (corresponding to the air supply passage (34) provided in the outer ring collar (31) of the first embodiment) and an outer supply passage (54b) that is connected to the inner supply passage (54a) and extends to the outer circumferential surface of the fixed housing (1) (corresponding to the air introduction passage (35) of the first embodiment).

[0043] The inner collar (32) is the same as that of the first embodiment, and its description is omitted by assigning the same reference numerals as in the first embodiment to each part thereof.

[0044] Conventionally, the inner diameter of the small diameter portion (51) is approximately the same as the inner diameter of the outer ring (3a) of the bearing (3). In this second embodiment, however, the inner diameter of the outer ring contact portion (52) is approximately the same as the inner diameter of the outer ring (3a) of the bearing (3), and the inner diameter of the inner ring collar opposing portion (53) is equal to the inner diameter of the outer ring collar (31) of the first embodiment. As a result, the inner circumferential surface (53a) of the inner ring collar opposing portion (53) of the small diameter portion (51) faces the outer circumferential surface (41a) of the first ring portion (41) of the inner ring collar (32) from the radially outside with a required gap.

[0045] A gap (G) is formed between the end face (53b) of the inner ring collar opposing portion (53) of the small diameter portion (51) that is closer to the bearing (3), and the end face (42a) of the opposing second ring portion (42) that is further away from the bearing (3), which serves as a guide passage (36) that guides the air blown out from the air supply passage (54) to the lateral hole (28A) of the oil drain passage (29). As a result, the air blown out from the air supply passage (54) of the small diameter portion (51) strikes the outer circumferential surface (41a) of the first ring portion (41) of the inner ring collar (32), changes direction, and a portion of it flows through the guide passage (36) into the oil drain passage (29) via the lateral hole (28A) provided in the outer ring contact portion (52) of the small diameter portion (51). At this time, the lubricating oil adhering to the end face (53b) of the inner ring collar opposing portion (53) of the small diameter portion (51) that is closer to the bearing (3) is carried along with the air and discharged from the oil discharge passage (29).

[0046] According to the spindle device of the machine tool of the second embodiment described above, the air supplied to the air supply passage (54) of the small diameter portion (51) of the fixed housing (1) causes the lubricating oil adhering to the end face (53b) of the inner ring collar opposing portion (53) of the small diameter portion (51) on the side closer to the bearing (3) to be discharged from the oil discharge passage (29). As a result, the adhesion of lubricating oil to the area around the small diameter portion (51), which is fixed and therefore likely to remain adhering to it and re-flow into the bearing (3), is eliminated. This prevents the temperature of the bearing (3) from rising and eliminates the problem of the spindle (2) deforming and affecting the machining accuracy of the machine tool.

[0047] Furthermore, similar to the first embodiment, the outer circumferential surface (42b) of the second ring portion (42) of the inner ring collar (32) is a tapered surface in which the outer diameter increases from the side closer to the bearing (3) to the side further away. This prevents lubricating oil from flowing back into the bearing (3) on the inner ring collar (32) side, thereby more reliably resolving the problem of affecting the machining accuracy of the machine tool. [Explanation of symbols]

[0048] (1): Fixed housing (2):Spindle (3): Bearings (3a): Outer ring (3b): Inner ring (4): Bearings (4a): Outer ring (4b): Inner ring (28A): Sideways hole (29):Drainage path (31): Outer ring collar (31a):Inner surface (31b): End face on the side closer to the bearing (4) (32): Inner collar (33): Notch (34): Air supply channel (35): Air intake path (36): Guide route (G): Gap (41): First ring section (41a):Outer surface (42): Second ring section (42a): End face on the side furthest from the bearing (42b):Outer surface (51): Small diameter section (52): Outer ring contact portion (53): Opposing part of inner ring collar (53a):Inner surface (53b): End face on the side closer to bearing (3) (54): Air supply channel (54a):Inner supply channel (54b):Outer supply channel

Claims

1. In a spindle assembly for a machine tool, the lubrication of multiple bearings that rotatably support the spindle relative to a fixed housing is performed by supplying oil-air to the bearings from one side through an oil supply passage, and discharging the oil-air used for lubricating the bearings from the other side through an oil discharge passage, and the spindle assembly is provided with multiple outer ring collars that hold the outer rings of multiple bearings and multiple inner ring collars that hold the inner rings of multiple bearings, and the required outer ring collars are provided with through holes that form part of the oil supply passage and notches that form part of the oil discharge passage, The outer ring collar, which has a notch that forms part of the oil drain passage, is provided with an air supply passage located near the notch and extending radially through it, and the fixed housing is provided with an air inlet passage that supplies air to the air supply passage of the outer ring collar from the fixed housing side. The spindle device of a machine tool is characterized in that the inner ring collar comprises a first ring portion whose outer circumferential surface faces the inner circumferential surface of the outer ring collar from the radially inward side with a required gap between them, and a second ring portion positioned between the first ring portion and the inner ring, wherein the outer diameter of the second ring portion is larger than the inner diameter of the outer ring collar, so that a gap is formed between the end face of the outer ring collar on the side closer to the bearing and the end face of the opposing second ring portion on the side further from the bearing, which serves as a guide passage for guiding air blown out from the air supply passage of the outer ring collar to the oil discharge passage.

2. In a spindle device for a machine tool, the lubrication of multiple bearings that rotatably support the spindle relative to a fixed housing is performed by supplying oil-air to the bearings from one side through an oil supply passage, and discharging the oil-air used for lubrication of the bearings from the other side through an oil discharge passage, and multiple outer ring collars are provided to hold the outer rings of the multiple bearings and multiple inner ring collars are provided to hold the inner rings of the multiple bearings, and the outer ring of the bearing located at the end of the multiple bearings abuts against a small diameter portion provided in the fixed housing without passing through an outer ring collar, and a horizontal hole is provided in the small diameter portion of the fixed housing that connects to a linear vertical hole provided in the fixed housing and forms part of the oil discharge passage, The small-diameter portion of the fixed housing consists of an outer ring contact portion that holds the outer ring of the bearing and is provided with a lateral hole that forms part of the oil drain passage, and an inner ring collar opposing portion whose inner diameter is smaller than the inner diameter of the outer ring contact portion. The fixed housing is provided with an air supply passage consisting of an inner through passage that penetrates the inner ring collar opposing portion of the small-diameter portion, and an outer through passage that is connected to the inner through passage and penetrates the outer portion of the fixed housing. The spindle device of a machine tool is characterized in that the inner ring collar comprises a first ring portion whose outer circumferential surface faces the inner circumferential surface of the inner ring collar opposing portion of the small diameter portion of the fixed housing from the radially inward side with a required gap, and a second ring portion positioned between the first ring portion and the inner ring, wherein the outer diameter of the second ring portion is larger than the inner diameter of the inner ring collar opposing portion of the small diameter portion of the fixed housing, so that a gap is formed between the end face of the inner ring collar opposing portion of the small diameter portion of the fixed housing that is closer to the bearing and the end face of the opposing second ring portion that is further from the bearing, which serves as a guide passage for guiding air blown out from the air supply passage to the oil discharge passage.

3. The spindle device of a machine tool according to claim 1 or 2, characterized in that the outer circumferential surface of the second ring portion of the inner ring collar is a tapered surface in which the outer diameter increases from the side closer to the bearing to the side further away.

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