WO2018181752A1

WO2018181752A1 - Bearing spacer for grease replenishment, bearing set, and spindle device

Info

Publication number: WO2018181752A1
Application number: PCT/JP2018/013330
Authority: WO
Inventors: 峰夫古山
Original assignee: Ntn株式会社
Priority date: 2017-03-30
Filing date: 2018-03-29
Publication date: 2018-10-04
Also published as: JP2018168952A

Abstract

A bearing spacer (3) is disposed on a compressed air supply side of a rolling bearing for applications in which compressed air (CA) is caused to pass through to the inside of a bearing space. The bearing spacer (3) comprises a set of an inner race spacer (11) and an outer race spacer (12). The set of the inner race spacer (11) and the outer race spacer (12) is configured in such a way as to enable grease to be retained in a space between the spacers. The bearing spacer (3) may be provided with non-contact seals which are provided at both ends, in the axial direction, of the outer race spacer (12), and inner diameter side ends of which come into contact with the inner race spacer (11) to seal the space between the spacers.

Description

Grease replenishing bearing spacer, bearing assembly and spindle device

Related applications

This application claims the priority of Japanese Patent Application No. 2017-067044 filed on Mar. 30, 2017, which is incorporated herein by reference in its entirety.

The present invention relates to a bearing spacer for grease replenishment combined with a rolling bearing used under a condition where compressed air penetrates the inside of the bearing, such as a spindle device with a built-in motor of a small machine tool, the bearing set and the spindle device. About.

¡Rolling bearings used for grease lubrication are generally used in a state where there is no positive inflow of air from outside into the bearing. In a spindle device of a large-sized or medium-sized machine tool having a built-in motor, the outer cylinder cooling is generally used to remove the heat generated by the motor and the bearing and stabilize the spindle temperature by circulating the cooling liquid to the housing side. However, in the spindle device of a small machine tool, if the coolant passage is provided, the outer diameter of the housing increases, which is disadvantageous for space-saving use. In addition, since an accessory device for circulating the coolant and a running cost are also required, the air cooling type in which the compressed air is allowed to penetrate inside the bearing may be used. In a spindle device with a built-in motor, a type that also serves as an air seal is adopted by flowing compressed air from the motor side and discharging the compressed air outside the housing near the tip of the spindle on the tool installation side (for example, Patent Document 1). )

As a general angular contact ball bearing used for a spindle device of a conventional machine tool, there are an open type having no seal between the inner ring 4 and the outer ring 5 shown in FIG. 8, and seals at both ends as shown in FIG. There are sealed types.

JP 2017-2971 A JP 2016-23719 A

Under the above-mentioned machine tool spindle device and other conditions where compressed air penetrates the bearing interior, grease and base oil gradually flow out, and especially the grease inside the bearing located at the cutting edge on the tool installation side decreases. Easy to do. Therefore, it is desired that the lubrication inside the bearing can be obtained stably over a long period of time. However, if the amount of grease filled inside the bearing is increased, the period of time during which the grease is retained increases, but the stirring resistance of the grease increases and the amount of heat generated during high-speed rotation increases. When the spindle device has a built-in motor, the temperature rises further due to the heat generated by the motor. In a spindle device of a machine tool or the like, heat generation from a bearing leads to a decrease in processing accuracy.

In addition, as a conventional general angular contact ball bearing, there are an open type of FIG. 8 and a sealed type of FIG. 9 as described above, but when used under the condition that the compressed air penetrates the inside of the bearing, Although the open type of FIG. 8 is easy to flow compressed air, grease is easily discharged. The arrows in FIG. 8 indicate the flow of compressed air. The sealed type in FIG. 9 is easy to hold the grease, but the compressed air hardly flows. For this reason, the cooling effect and air sealing effect of the motor and the bearing are reduced.

A proposal has been made to improve the lubrication effect of the enclosed grease by providing a grease pocket in the vicinity of the rolling element rolling on the inner circumference of the outer ring. However, there is a limit to the sealing of the grease in the bearing, and it is desired that the lubrication can be stably obtained over a longer period.

An object of the present invention is to provide a grease replenishing bearing spacer, a bearing assembly, and a spindle device that can stably obtain lubrication inside the bearing for a long period of time under a condition where compressed air penetrates.

The grease replenishing bearing spacer of the present invention is a bearing spacer arranged on the compressed air supply side in a rolling bearing for use in passing compressed air into the bearing space, and is a set of an inner ring spacer and an outer ring spacer. The set of the inner ring spacer and the outer ring spacer is configured such that grease can be held in the space between the both spacers.

According to this configuration, the grease and its base oil inside the bearing spacer gradually move due to the compressed air, and move into the adjacent bearing, thereby supplying the reduced grease and its base oil in the bearing. To do. Thereby, the lifetime improvement of a bearing is obtained stably. For this reason, the initial amount of grease in the bearing is small, and unlike the case of increasing the amount of grease in the bearing, there is no problem of increase in stirring resistance, and heat generation is suppressed and high-speed rotation can be achieved. Further, since the spacer is provided with a function of holding the grease, it is only necessary to interpose it, it can be easily installed in the housing, and a large amount of grease can be held with a simple configuration.
The position where the grease is held in the bearing spacer is not particularly limited, but it is necessary to allow compressed air to pass therethrough. For example, by applying a method of applying to the inner peripheral surface of the outer ring spacer, the compression is performed. It can easily cope with the passage of air.

The grease replenishing bearing spacer of the present invention has a non-contact seal provided at both ends in the axial direction of the outer ring spacer and having an inner diameter side end close to the inner ring spacer to seal the inner space of the spacer. Also good. When the seal members are provided at both ends of the bearing spacer, excessive internal grease is prevented from flowing out, and the bearing is replenished in small amounts over a long period of time.

A bearing assembly with a grease replenishing function according to the present invention includes a rolling bearing for use in which compressed air is allowed to pass through a bearing space, and a bearing spacer having any one of the above-described structures disposed on the compressed air supply side of the rolling bearing. Prepare. According to the bearing set having this configuration, the above-described operations and effects described for the grease replenishing bearing spacer of the present invention can be obtained.

In the bearing assembly with a grease replenishment function according to the present invention, replenishment grease is held in the grease replenishing bearing spacer, bearing grease is enclosed in the rolling bearing, and the replenishment grease is more than the bearing grease. The base oil viscosity may be low. The grease in the bearing spacer for replenishing grease is located far from the place where lubrication is required compared to the sealed grease in the bearing. Replenishment of the required lubrication location is performed more smoothly and stably.

In the bearing assembly with a grease replenishing function according to the present invention, the inner ring spacer may be a member having the same specification as the inner ring of the rolling bearing, and the outer ring spacer may be a member having the same specification as the outer ring of the rolling bearing. Or the 2nd seal member which seals the spacer internal space of the said bearing spacer may be a member of the same specification as the 1st seal member which seals the both ends of the bearing space of the said rolling bearing. According to this configuration, it is possible to share the component parts between the rolling bearing and the bearing spacer.

The spindle device according to the present invention is formed in the housing, the bearing set having any one of the above-described configurations for supporting the main shaft, the motor for driving the main shaft, the housing for housing the bearing set and the motor, and the housing. A compressed air ventilation path that passes through the outer periphery of the motor and through the bearing space of the bearing set.
The grease replenishing bearing spacer and the bearing assembly of the present invention, when applied to such a spindle device, can stably obtain the lubrication inside the bearing for a long time under the condition that the compressed air penetrates. The effect is exhibited more effectively.

Any combination of at least two configurations disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the present invention.

The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.
It is sectional drawing which shows the bearing set with a grease replenishment function which concerns on 1st Embodiment of this invention. It is sectional drawing of the spindle apparatus using the bearing set. It is sectional drawing of the other example of the spindle apparatus using the same bearing set. It is sectional drawing of the further another example of the spindle apparatus using the same bearing set. It is sectional drawing of an example of the bearing which comprises the bearing set. It is sectional drawing which shows the bearing set with a grease replenishment function which concerns on other embodiment of this invention. It is sectional drawing which shows the bearing set with a grease replenishment function which concerns on other embodiment of this invention. It is sectional drawing of a prior art example. It is sectional drawing of another prior art example.

A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a bearing set using a grease replenishing bearing spacer according to this embodiment, and FIG. 2 shows an example of a spindle device using this bearing set. In FIG. 1, the bearing set 1 includes two

bearings

2 and 2 that are rolling bearings and one bearing spacer 3 that is a grease-supplementing bearing spacer.

As shown in an enlarged view in FIG. 5, each bearing 2 is an angular contact ball bearing with a seal, and a plurality of rolling elements 6 made of balls are interposed between

raceway surfaces

4a and 5a of the inner ring 4 and the outer ring 5, The rolling element 6 is held in the pocket of the cage 7.

First seal members

8 and 9 are attached to the inner periphery of the outer ring 5 to seal both ends of a bearing space formed between the inner and

outer rings

4 and 5. These

first seal members

8, 9 constitute a non-contact seal (labyrinth seal) having an inner diameter end close to the outer peripheral surface of the inner ring 4 and a gap between the inner ring 4 and the

first seal members

8, 9. ing. The

first seal members

8 and 9 are attached to the outer ring 5 by fitting the outer peripheral edges of the

first seal members

8 and 9 into the seal mounting grooves 17 provided on the inner peripheral surface of the outer ring 5. .

On the inner peripheral surface of the outer ring 5, an annular grease pocket 10 is formed adjacent to the raceway surface on the front side. The outer peripheral surface on the front side (bearing back side) following the raceway surface of the inner ring 4 is formed in a tapered surface that becomes smaller in diameter as it approaches the end.

In FIG. 1, both

bearings

2 and 2 are installed back to back, and the grease pocket 10 is arranged on the non-adjacent side with respect to the outer ring raceway surface 5a.

The bearing spacer 3 includes a set of an inner ring spacer 11 and an outer ring spacer 12. The inner ring spacer 11 is provided adjacent to the inner ring 4 of the bearing 2 in the axial direction, and the outer ring spacer 12 is provided adjacent to the outer ring 5 of the bearing 2 in the axial direction. The bearing spacer 3 holds the grease G1 in a space between the inner ring spacer 11 and the outer ring spacer 12 (hereinafter simply referred to as “spacer space”). Hereinafter, the grease G1 held in the spacer space is referred to as “replenishment grease G1”. The bearing spacer 3 has

second seal members

13 and 14 attached to both ends in the axial direction. The

second seal members

13 and 14 constitute a non-contact seal (labyrinth seal) that is attached to the outer ring spacer 12 and whose inner diameter end is close to the inner peripheral surface of the inner ring spacer 13 to seal the spacer space. .

In this embodiment, the inner ring spacer 11 and the outer ring spacer 12 of the bearing spacer 3 are members having the same specifications as the inner ring 5 and the outer ring 6 of the bearing 2, respectively. The

second seal members

13 and 14 are also members having the same specifications as the

first seal members

8 and 9 of the bearing 2. In this way, the components are shared between the bearing 2 and the bearing spacer 3. Therefore, the outer ring spacer 12 has the grease pocket 10 and the raceway surface 5a formed on the inner peripheral surface, and the seal mounting groove 17 is formed, and the

second seal members

13 and 14 are formed in the seal mounting groove 17. Installed.

The inner ring spacer 11 and the outer ring spacer 12 of the bearing spacer 3 may be parts dedicated to the spacer different from the bearing 2. In that case, for example, as shown in FIG. 6, the outer peripheral surface of the inner ring spacer 11 and the inner peripheral surface of the outer ring spacer 12 may be simple cylindrical surfaces. In the example of the figure, the inner peripheral surface of the outer ring spacer 12 is a cylindrical surface, but has seal mounting grooves 17 at both ends.

When the inner ring spacer 11 and the outer ring spacer 12 of the bearing spacer 3 are dedicated spacer parts, the

second seal members

13A and 14A at both ends are formed integrally with the outer ring spacer 11 as shown in FIG. May be. 6 and FIG. 7, between the

seal members

13 and 13A of the bearing spacer 3 and the seal member 9 of the bearing 2 adjacent thereto, and / or the seal member 8 of the bearing 2 and the front end side. Grease may also be enclosed in advance between the seal member 8 of the bearing 2.

In each bearing set 1, the replenishment grease G <b> 1 is held in the bearing spacer 3 by applying the replenishment grease G <b> 1 to the inner peripheral surface of the outer ring spacer 12. Each bearing 2 is also sealed with grease G2 by applying grease G2 to the inner peripheral surface of the outer ring 5 or the like. Hereinafter, the grease G2 sealed in the bearing 2 is referred to as “bearing grease”. The replenishment grease G1 in the bearing spacer 3 and the bearing grease G2 in the bearing 2 are preferably the same type. The viscosities of the base oils of these greases G1 and G2 are preferably the same, or the replenishment grease G1 is preferably softer (lower viscosity) than the bearing grease G2. These greases G1 and G2 may be soap-based or non-soap-based such as urea-based.

FIG. 2 shows an example of the spindle device S using the bearing set 1 of FIG. This spindle device is a spindle device of a machine tool, and includes a plurality of bearing sets 1 and 31 that support a main shaft 21 and a motor 23 that drives the main shaft 21. The bearing sets 1 and 31 and the motor 23 are accommodated in the inner peripheral hole 20a of the same housing 20 side by side in the axial direction. The spindle 21 has a spindle head 21a to which a tool (not shown) is attached at the tip. The rear part of the main shaft 21 is driven by the motor 23. Although not shown, the motor 23 includes a rotor provided on the outer periphery of the main shaft 21 and a stator provided on the inner periphery of the motor case. The motor 23 is installed on the outer periphery of the inner peripheral surface of the housing 20 via a gap.

In the spindle device S of the figure, of the two bearing sets at the front portion of the spindle 21, the bearing set on the spindle head 21a side is the bearing set 1 having the bearing spacer 3 of the embodiment of FIG. The bearing set 31 is a bearing set that does not have the bearing spacer 3. In the bearing set 1 having the bearing spacer 3, the bearing spacer 3 is arranged at the most upstream side of the flow of the compressed air CA (that is, the compressed air CA supply side), that is, at the motor 23 side end.

As shown in FIG. 3, the bearing set 1 having the bearing spacer 3 may be arranged on the motor 23 side. As shown in FIG. 4, both the bearing sets are bearings having the bearing spacer 3. Set 1 may be used.

2, a ventilation path 25 for compressed air CA is formed in the housing 20 so as to pass through the outer periphery of the motor 23 and through the bearing space in each of the bearing sets 1 and 31. A compressed air inlet 25 a that forms part of the ventilation path 25 is provided on the end face wall of the rear end of the housing 20. The compressed air inlet 25a is connected to a compressed air supply source (not shown) such as a blower by piping. The compressed air outlet 25b that forms a part of the ventilation path 25 is formed by a gap between the front end opening of the inner peripheral hole 20a of the housing 20 and a shielding plate provided at an inner position of the spindle head 21a of the spindle 21. Yes.

In the spindle device S having this configuration, the compressed air CA passes through the outer periphery of the motor 23 and the bearing space of each bearing 2, whereby the motor 23 and each bearing 2 are cooled. Since the compressed air CA flows in each bearing 2, the outer diameter of the housing 20 can be made compact compared to a configuration in which a path for liquid cooling is provided in the housing 20, but on the other hand, bearing grease G 2 in each bearing 2. And its base oil gradually flows out due to the compressed air CA.

However, in this embodiment, the replenishment grease G1 inside the bearing spacer 1 gradually moves and moves into the bearings 2 arranged on the downstream side of the compressed air flow, thereby reducing the bearing grease G2 within the bearings 2. And replenish its base oil. Thereby, the lifetime improvement of the bearing 2 is obtained stably. Since the initial amount of the bearing grease G2 is small, unlike the case where the bearing grease G2 is increased, the problem of an increase in stirring resistance does not occur, and heat generation can be suppressed and high-speed rotation can be achieved. Further, since the bearing spacer 3 has a function of holding the replenishment grease G1, the bearing spacer 3 may be simply interposed between the

bearings

2 and 2 or between the stepped surfaces of the bearing 2 and the housing 20. Can be easily installed, and a large amount of grease can be held with a simple configuration.

Further, since the bearing spacer 3 of this embodiment has the

second seal members

13 and 14 at both ends thereof, it is possible to prevent the replenishment grease G1 inside the bearing spacer 3 from flowing out excessively, and for a long period of time. As a result, the bearing 2 is replenished little by little.

The arrangement of the bearing spacers 3 in the spindle device S may be appropriately set according to the characteristics of the spindle device S and the like. For example, the compressed air outlet 25b in the housing 20 has a high flow rate because the compressed air CA is released to the atmosphere, and the bearing grease G2 is easily discharged in the vicinity thereof. Therefore, as shown in the example of FIG. 2, by providing the bearing spacer 3 on the bearing set 1 on the spindle head 21a side, the bearing 2 for replenishing the bearing grease G2 is replenished from the bearing spacer 3 for replenishing grease. Grease G1 can be supplied. When the bearing spacer 3 for replenishing grease is arranged in the bearing set 1 on the motor 23 side (upstream side) as in the example of FIG. 3, the bearing set 31 that does not have the downstream bearing spacer 3 is included. In addition, the replenishment grease G1 can be supplied to the entire bearing 2. When the bearing spacer 3 for replenishing grease is provided in both the front and rear bearing sets 1 as in the example of FIG. 4, the amount of grease retained can be increased to further improve the durability of the grease.

As mentioned above, although the form for implementing this invention based on the Example was demonstrated, embodiment disclosed here is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 ... Bearing set 2 ... Bearing (rolling bearing)
DESCRIPTION OF SYMBOLS 3 ... Bearing spacer 4 ... Inner ring 5 ... Outer ring 6 ... Rolling body 7 ...

Cage

8, 9 ... Seal member 10 ... Grease pocket 11 ... Inner ring spacer 12 ...

Outer ring spacer

13, 14 ... Seal member (non-contact seal)
20 ... Housing 21a ... Spindle head 21 ... Spindle 23 ... Motor 25 ... Ventilation path 25a ... Compressed air inlet 25b ... Compressed air outlet 31 ... Bearing set S ... Spindle device

Claims

A bearing spacer arranged on the compressed air supply side in a rolling bearing for use in passing compressed air through the bearing space,
It consists of a set of inner ring spacer and outer ring spacer,
The set of the inner ring spacer and the outer ring spacer is configured to be able to hold grease in the space between both spacers,
Bearing spacer.
The bearing spacer according to claim 1, further comprising a non-contact seal provided at both ends in the axial direction of the outer ring spacer and having an inner diameter side end close to the inner ring spacer and sealing the inner space of the spacer. .
A rolling bearing for the purpose of passing compressed air through the bearing space;
The bearing spacer according to claim 1, which is disposed on a compressed air supply side in the rolling bearing,
A bearing assembly comprising:
In the bearing set according to claim 3,
Replenishment grease is held in the grease replenishing bearing spacer, bearing grease is enclosed in the rolling bearing,
A bearing assembly in which the replenishment grease has a lower base oil viscosity than the bearing grease.
5. The bearing set according to claim 3, wherein the inner ring spacer is a member having the same specification as the inner ring of the rolling bearing, and the outer ring spacer is a member having the same specification as the outer ring of the rolling bearing.
In the bearing set according to any one of claims 3 to 5,
The rolling bearing includes a first seal member that seals both ends of the bearing space;
The bearing spacer is provided at both ends of the outer ring spacer in the axial direction, and an inner diameter side end is provided with a second seal member that seals the inner space of the spacer close to the inner ring spacer,
A bearing set in which the second seal member is a member having the same specifications as the first seal member.
The bearing set according to any one of claims 3 to 6, which supports a main shaft;
A motor for driving the spindle;
A housing for housing the bearing set and the motor;
A vent path for compressed air formed in the housing and passing through the outer periphery of the motor and in the bearing space of the bearing set;
A spindle device comprising: