JP2008101631A - Rolling bearing with seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing with a seal capable of preventing heat generation due to contact between an inner ring seal groove and a seal lip.
SOLUTION: A plurality of balls 3 are interposed between raceway surfaces 1a, 2a facing an inner ring 1 and an outer ring 2, and these balls 3 are held at equal intervals by a cage 4. A seal 6 that seals the end of the space between the inner and outer rings 1 and 2 is attached to the outer ring 2, and a seal lip 11 b of the seal 6 is inserted into an annular inner ring seal groove 8 provided on the outer diameter surface of the inner ring 1. The inner ring 1 is positioned without contact. The distance between the inner surface of the inner ring seal groove 8 on the inner ring end face side and the side surface of the seal lip 11b is 40 to 43% of the groove width of the inner ring seal groove 8.
[Selection] Figure 1

Description

  The present invention relates to a sealed rolling bearing used for a main shaft of a machine tool, and more particularly to a sealed rolling bearing suitable for grease lubrication.

In a sealed angular contact ball bearing used for a spindle of a machine tool, grease is stored as a lubricant inside the bearing, and both ends of the bearing internal space are sealed with seals. Unlike the oil-lubricated type, such a grease-filled angular ball bearing with a seal does not require a special lubrication device, so that the machine tool spindle in which the bearing is incorporated can be made compact. Further, since a lubrication device is unnecessary, there is an advantage that only the bearing needs to be replaced in the operation of replacing the bearing.
Further, in the case of a sealed angular contact ball bearing that supports the spindle of such a machine tool, since it rotates at about dn = 600,000, as shown in FIG. 9, as a seal that seals both ends of the bearing internal space, By using a non-contact seal 36 of a type in which the seal lip 36a and the inner ring seal groove 38 do not contact each other, a device for suppressing the temperature rise is made (for example, Patent Document 1). As a result, the heat generation of the bearing accompanying the contact between the seal lip 36a and the inner ring seal groove 38 and further the heat generation of the machine tool main spindle are suppressed, and it is possible to avoid deterioration of the accuracy of the workpiece due to this heat generation.
JP 2002-122149 A

  However, in the rolling bearing with a seal shown in FIG. 9, the inner ring seal groove 38 and the outer ring seal mounting groove 39 may be close to each other depending on the inner ring seal groove 38 and the seal lip 36a. Depending on the case, the inner ring seal groove 38 and the seal lip 36a may come into contact with each other, and heat may be generated by sliding contact at the contact portion.

  An object of the present invention is to provide a rolling bearing with a seal that can prevent heat generation due to contact between an inner ring seal groove and a seal lip.

The rolling bearing with seal according to the present invention includes a plurality of balls interposed between the raceways facing the inner ring and the outer ring, and a cage for holding the balls at equal intervals, thereby sealing the end of the space between the inner and outer rings. The seal to be fitted is fitted in a seal mounting groove provided in the outer ring, and the seal lip of this seal is located in an annular inner ring seal groove provided in the outer diameter surface of the inner ring so as not to contact the inner ring. In the rolling bearing, the distance between the inner surface of the inner ring seal groove on the inner ring end face side and the side surface of the seal lip is a distance at which the seal lip and the inner ring seal groove are held in a non-contact manner. This distance is, for example, 40 to 43% of the groove width of the inner ring seal groove.
According to this configuration, the distance between the inner side surface of the inner ring seal groove on the inner ring end face side and the side surface of the seal lip is set to, for example, 40% or more of the groove width of the inner ring seal groove. Even if dimensional fluctuations within tolerance occur in the groove, contact between the inner ring end face side inner face of the inner ring seal groove and the seal lip can be avoided, and for example, 43% or less. Contact between the inner surface and the seal lip can also be avoided. Thus, contact between the inner ring seal groove and the seal lip can be avoided, and heat generation due to the contact can be prevented.

  In the present invention, the rolling bearing may be an angular ball bearing. In the case of an angular ball bearing, the problem of heat generation due to the contact of the seal lip is large, and the effect of preventing heat generation by avoiding the contact of the seal lip according to the present invention is effective.

  In the present invention, the rolling bearing with seal may be a bearing that supports a main shaft of a machine tool. In this configuration, in the bearing that supports the main shaft, there is no contact between the inner ring seal groove and the seal lip, and heat generation of the bearing due to the contact is suppressed, so heat generation of the main shaft is also suppressed, and work caused by heat generation of the main shaft is suppressed. It is possible to suppress deterioration in accuracy.

  The rolling bearing with seal according to the present invention includes a plurality of balls interposed between the raceways facing the inner ring and the outer ring, and a cage for holding the balls at equal intervals, thereby sealing the end of the space between the inner and outer rings. The seal to be fitted is fitted in a seal mounting groove provided in the outer ring, and the seal lip of this seal is located in an annular inner ring seal groove provided in the outer diameter surface of the inner ring so as not to contact the inner ring. In a rolling bearing, the inner ring seal groove and the seal are arranged so that the distance between the inner surface of the inner ring seal groove on the inner ring end face side and the side surface of the seal lip is a distance at which the seal lip and the inner ring seal groove are held in a non-contact manner. Heat generation due to contact with the lip can be prevented.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a sectional view of a rolling bearing with a seal according to this embodiment, and FIG. 2 shows a partially enlarged sectional view thereof. This rolling bearing 10 is an angular ball bearing in which a plurality of balls 3 are interposed between raceway surfaces 1a, 2a facing the inner ring 1 and the outer ring 2, and is used for grease lubrication. The balls 3 are held by a cage 4 so as to roll freely at a predetermined interval in the circumferential direction. The cage 4 is guided by the inner diameter surface of the outer ring 2. Each of the raceway surfaces 1 a and 2 a provided on the outer diameter surface of the inner ring 1 and the inner diameter surface of the outer ring 2 has a contact angle with the ball 3 at a predetermined angle. On the outer diameter surface of the inner ring 1, a counter bore 5 is provided on one side of the raceway surface 1a, that is, on the side opposite to the direction in which the contact angle is generated. An inner diameter surface of the outer ring 2 is a cylindrical surface, and no counter bore is provided. At the time of assembling the bearing, the angular ball bearing 10 can be assembled by heating the outer ring 2 to which the ball 3 is assembled and inserting the inner ring 1 from the counter bore 5 side.

  The outer ring 2 is provided with a pair of cored seals 6 and 6A for sealing both ends of the space between the inner and outer rings 1 and 2. Specifically, a pair of seal mounting grooves 7 and 7A are formed annularly at both ends of the inner diameter surface of the outer ring 2 in the circumferential direction, and the seals 6 and 6A are provided in these seal mounting grooves 7 and 7A. Mated. One seal 6 is an annular member made of a composite of an elastic member 11 such as rubber and a cored bar 12 as a reinforcing member, and the outer peripheral part of the cored bar 12 is an elastic swelling that is the outer peripheral edge of the elastic member 11. It is embedded in the protruding portion 11 a and is a fixed side of the cored bar 12. Further, the inner peripheral portion of the cored bar 12 is embedded in a seal lip 11 b that is an inner peripheral portion of the elastic member 11. The other seal 6A is also an annular member made of a composite of the elastic member 11 and the cored bar 12. The outer peripheral edge of the elastic member 11 is an elastic bulge 11a, and the inner peripheral edge of the elastic member 11 is a seal lip. 11b.

  An annular inner ring seal groove 8 is provided in the shoulder on the outer diameter surface of the inner ring 1 opposite to the counter bore 5 in the circumferential direction, and the seal of one seal 6 is sealed in the inner ring seal groove 8. The lip 11b is positioned in non-contact with the inner ring 1. In this case, the distance between the inner surface of the inner ring seal groove 8 on the inner ring end face side and the side surface of the seal lip 11b is 40 of the groove width of the inner ring seal groove 8 so that the seal 6 and the inner ring seal groove 8 do not contact each other. It is said to be 43%. The counter bore 5 on the outer diameter surface of the inner ring 1 is provided with a seal lip 11b on the inner peripheral edge of the other seal 6A that is not in contact with the inner ring 1.

Next, in this rolling bearing 10 with a seal, the basis that the distance between the inner surface of the inner ring seal groove 8 on the inner ring end face side and the side surface of the seal lip 11 b is 40 to 43% of the groove width of the inner ring seal groove 8. Will be described with reference to FIGS.
FIG. 3 shows a partial sectional view of a conventional example of a rolling bearing with a seal having substantially the same structure as that of this embodiment, and the same members are denoted by the same reference numerals as those of the embodiment. The only difference from the embodiment is the mounting position of the seal 6 with respect to the outer ring 2. The specifications of this sealed roller bearing 10A are as follows.
・ Bearing model number: BNS012 (manufactured by NTN)
・ Axial load: 198 N
・ Rotation speed: 10000min ^-1
・ Enclosed grease: MP-1 (Nippon Grease Co., Ltd.)
・ Enclosed amount: 45% of bearing static space
In this conventional example, the dimensions of each part indicated by the reference numerals of the attachment portions of the seal 6 shown in FIG.

Further, in FIG. 5 showing the details of the inner ring seal groove 8 facing the seal lip 11b of the seal 6 in an enlarged sectional view,
・ Gap between the side surface at the tip of the seal lip 11b and the slope on the inlet side of the inner ring seal groove 8: 0.3 mm
-Groove width of inner ring seal groove 8 at the tip of seal lip 11b: 1.1 mm
・ Variation width of the gap due to tolerance: 0.24mm
It is said that. The dimensions of the inner ring seal groove 8 were measured using an optical microscope.
The gap fluctuation width due to tolerance is as shown in FIG.
tolerance of a + tolerance of c + tolerance of (φD1-φd1) x tan40 ° (1)
= 0.06 + 0.06 + 0.14tan40 °
= 0.237
Is calculated as

From these values, the distance between the tip side surface of the seal lip 11b and the inner side surface on the inner ring end face side of the inner ring seal groove 8 is 0.06 to 0.54 (0.3−0.237 to 0.3 + 0.237) mm, but the bearing 10A. The seal 6 and the inner ring seal groove 8 may be in contact with each other depending on the condition of the seal and the flatness of the seal 6.
Therefore, when the flatness of the side surface of the seal 6 was measured, the measurement results shown in Table 2 were obtained.

  In this flatness measurement, as shown in FIG. 6, the bearing 10 </ b> A was rotated once with the dial gauge 23 applied to the side surface of the seal 6, and the unevenness of the seal 6 was measured.

  When the result of the flatness measurement is added to the gap value of 0.06 to 0.54 mm, it is desirable that the gap value is at least about 0.2 mm in order to prevent contact between the seal lip 11b and the inner ring seal groove 8. . That is, it is necessary to make the gap larger by 0.14 (= 0.2−0.06) mm than in the conventional example. Specifically, the side surface at the tip of the seal lip 11b and the inner surface at the inner ring end face side of the inner ring seal groove 8 Must be 0.44 (= 0.3 +0.14) mm or more. Since the groove width of the inner ring seal groove 8 is 1.1 mm, in other words, the distance between the tip side surface of the seal lip 11 b and the inner surface of the inner ring seal groove 8 on the inner ring end face side is set to 40 of the groove width of the inner ring seal groove 8. % (0.44 / 1.1 = 0.4) or more.

  On the other hand, in FIG. 5, the clearance between the inner surface of the inner ring seal groove 8 surrounded by circles on the raceway surface 1a side and the side surface of the seal lip 11b is 0.5 mm. Therefore, similarly to the above case, when the fluctuation range of the gap due to tolerance is obtained, it is 0.13 mm. That is, since the inner surface of the inner ring seal groove 8 on the raceway surface 1a side has an angle of 5 °, in the above formula (1), when tan 5 ° is substituted for tan 40 °, the width is 0.13 mm. Taking this into account, the gap between the inner surface of the inner ring seal groove 8 surrounded by circles on the raceway surface 1a side and the side surface of the seal lip 11b is 0.37 to 0.63 mm. Further, considering the contact due to the flatness of the seal 6, a gap of about 0.2 mm is desirable. Therefore, the upper limit of the amount by which the seal 6 is displaced to the inner surface on the raceway surface 1 a side of the inner ring seal groove 8 is 0.17 (= 0.37). The distance between the tip side surface of the seal lip 11b and the inner side surface of the inner ring seal groove 8 on the inner ring end surface side at this time is 0.47 (= 0.3 + 0.17) mm. That is, the distance between the side surface at the tip of the seal lip 11b and the inner surface on the inner ring end face side of the inner ring seal groove 8 needs to be 43% (0.47 / 1.1≈0.43) or less of the groove width of the inner ring seal groove 8.

  Thus, according to this rolling bearing 10 with a seal, the distance between the inner surface of the inner ring seal groove 8 on the inner ring end face side and the side surface of the seal lip 11b is 40 to 43% of the groove width of the inner ring seal groove 8. Therefore, contact between the inner ring seal groove 8 and the seal lip 11b can be avoided, and heat generation due to the contact can be prevented.

  FIG. 7 shows a spindle device portion in a machine tool using the sealed rolling bearing (angular ball bearing) 10 of the embodiment of FIG. In the spindle device of this machine tool, the main shaft 13 is supported by a pair of angular ball bearings 10 and 10 and another rolling bearing 14. The pair of angular ball bearings 10, 10 support the front portion of the main shaft 13, and another rolling bearing 14 supports the rear portion of the main shaft 13. Both angular ball bearings 10 and 10 are installed in a combination of the back surfaces, for example. As another rolling bearing 14, a cylindrical roller bearing or the like is used. This spindle device is of a built-in motor type, and the rotor 16 of the motor 15 is provided on the outer periphery of the main shaft 13, and the stator 17 corresponding to the rotor 16 is provided on the inner periphery of the housing 18. The housing 18 has a bearing cooling jacket 19 and a motor cooling jacket 20.

  FIG. 8 shows a spindle bearing portion of a machine tool. The main shaft 13 is supported by a housing (not shown) via a plurality of angular ball bearings 10 and 10 arranged side by side on the left and right. These angular ball bearings 10 are the rolling bearings with seals shown in FIG. 1 and are arranged in a back combination. An inner ring spacer 21 and an outer ring spacer 22 are interposed between the inner rings 1 and 1 and between the outer rings 2 and 2 of the angular ball bearings 10 and 10.

  Thus, when the rolling bearing 10 with a seal of the embodiment of FIG. 1 is used for the main shaft bearing portion of the machine tool, there is no contact between the inner ring seal groove 8 and the seal lip 11b in the bearing 10 supporting the main shaft. Since the heat generation of the bearing 10 due to the contact is suppressed, the heat generation of the main shaft 13 is also suppressed, and the accuracy deterioration of the workpiece due to the heat generation of the main shaft 13 can be suppressed.

It is a fragmentary sectional view of the rolling bearing with a seal concerning one embodiment of this invention. It is a partial expanded sectional view of the rolling bearing with the seal. It is a fragmentary sectional view of the conventional rolling bearing with a seal used for the ground explanation of the distance setting of the inner ring seal groove and seal lip in the rolling bearing with the seal. It is a partial expanded sectional view which shows the seal attachment part in FIG. FIG. 4 is a partially enlarged sectional view showing a portion of an inner ring seal groove in FIG. 3. It is explanatory drawing of the flatness measurement of the rolling bearing with a seal | sticker of FIG. It is a fragmentary sectional view of the spindle apparatus in the machine tool using the rolling bearing with a seal concerning the embodiment of FIG. It is a fragmentary sectional view of the spindle bearing part of the machine tool using the rolling bearing with a seal concerning the embodiment of FIG. It is a fragmentary sectional view of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inner ring 2 ... Outer ring 1a, 2a ... Raceway surface 3 ... Ball 4 ... Cage 6, 6A ... Seal 7 ... Seal mounting groove 8 ... Inner ring seal groove 11b ... Seal lip 13 ... Main shaft

Claims (4)

A plurality of balls are interposed between the raceways facing the inner ring and the outer ring, a cage is provided to hold the balls at equal intervals, and a seal that seals the end of the space between the inner and outer rings is provided on the outer ring. In a rolling bearing with seal in which the seal lip is fitted in a seal mounting groove and the seal lip of this seal is positioned in a non-contact manner with the inner ring in an annular inner ring seal groove provided on the outer diameter surface of the inner ring.
A rolling bearing with a seal, characterized in that the distance between the inner surface of the inner ring seal groove on the inner ring end face side and the side surface of the seal lip is a distance at which the seal lip and the inner ring seal groove are held in a non-contact manner.   The rolling bearing with seal according to claim 1, wherein the distance between the inner side surface of the inner ring seal groove on the inner ring end face side and the side surface of the seal lip is 40 to 43% of the groove width of the inner ring seal groove.   3. A rolling bearing with a seal according to claim 1 or 2, which is an angular ball bearing.   The rolling bearing with a seal according to any one of claims 1 to 3, wherein the rolling bearing has a seal and is a bearing that supports a main shaft of a machine tool.

Images