JP2012088176A - Device and method for strength confirmation of ring member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for strength confirmation of a ring member with which strength of a ceramic ring member can be simply confirmed and which can deal with total inspection in mass production of the ring member.SOLUTION: The device for strength confirmation comprises an oil pressure loading pedestal 1 which includes: a fitted part 5 into which a ceramic ring member W can be set in a state where an inner peripheral surface Wa of the ring member is fitted; and a support part 6 for supporting the ring member W fitted into the fitted part 5. In the oil pressure loading pedestal 1, an oil path 18 which opens facing the inner peripheral surface Wa of the ring member W fitted to the fitted part 5 and applies oil pressure to the inner peripheral surface Wa is formed. The device for strength confirmation further comprises: a lid 2 which covers the ring member W fitted to the fitted part 5 and is openably/closably provided to the oil pressure loading pedestal 1; and an oil pressure supply source 3 which is piped and connected to the oil path 18 of the oil pressure loading pedestal 1 and can supply defined oil pressure to the inner peripheral surface Wa of the ring member W.

Description

  The present invention relates to a ring member strength confirmation device and a strength confirmation method in the case where ceramics are used as a ring member for a bearing ring or the like.

  Opportunities to use ceramics that are lightweight, have a low coefficient of linear expansion, and are electrically insulating for bearing rings are increasing. For example, in the machine tool-related industry, there is a machine tool intended to increase the speed by applying ceramics to the inner ring and reducing an increase in preload while suppressing an expansion amount by a temperature rise and centrifugal force. In addition, there is use in a magnetic field such as a magnetic bearing by utilizing a characteristic that ceramics are electrically insulated.

  When ceramics are used for bearings, the problem is brittle damage (brittle fracture). In particular, when ceramics are used for the inner ring on the rotating side, it is necessary to examine the initial fit between the inner ring and the shaft, the temperature rise of the shaft, and the hoop stress, which is the normal stress component in the circumferential direction caused by the rotation. is there. This is because the inner ring can be regarded as a thin-walled cylinder, and when receiving an internal pressure or centrifugal force, the hoop stress acting on the inner diameter of the inner ring is generally larger than the stress in other directions.

  In bearings for machine tools that use ceramics for the inner ring, there is an example in which the strength of the ceramic inner ring is examined assuming a hoop stress generated during operation (Non-Patent Document 1). In this example, a ceramic inner ring is fitted on the shaft, and the calculation is expected when actually operating based on the material mechanical hoop stress value calculated from the tightening allowance and temperature while heating in a thermostatic bath. In this method, the strength of the material is confirmed by comparing the hoop stress values.

NTN technical review, 76, 80-87, 2008

  In a conventional method for confirming the strength of the ceramic inner ring, the shaft and the ceramic inner ring are tightly fitted, that is, heated as an interference fit. This gives stress to the ceramic inner ring due to thermal expansion of the shaft. Although this method has no problem for implementation at the laboratory level, it is too laborious as a quality assurance method for actual products. Therefore, it takes labor and time to confirm the strength, and is not suitable for 100% inspection at the time of mass production.

  An object of the present invention is to provide a strength confirmation device and strength confirmation method for a ring member that can easily confirm the strength of a ring member made of ceramics, and can also be used for 100% inspection during mass production of this ring member. It is to be.

  The strength confirmation device for a ring member according to the present invention is a strength confirmation device for confirming the strength of a ceramic ring member, and a mounted portion capable of mounting the ring member in a fitted state on an inner peripheral surface, and the mounted An oil passage is formed which has a support portion for supporting the ring member mounted on the portion and opens to face the inner peripheral surface of the ring member mounted on the mounted portion and applies hydraulic pressure to the inner peripheral surface. An oil pressure load seat, a ring member mounted on the mounted portion, a lid provided on the oil pressure load seat so as to be openable and closable, and a hydraulic pressure determined by piping connected to an oil passage of the oil pressure load seat And a hydraulic pressure supply source capable of being supplied to the inner peripheral surface of the ring member.

According to this configuration, with the lid open, the inner peripheral surface of the ceramic ring member is fitted in the fitted portion of the hydraulic pressure load seat, and the ring member is supported by the support portion. Next, the lid covering the ring member is closed and fixed with a bolt or the like so that the ring member is not damaged and scattered outside when an oil pressure is applied. Next, a predetermined hydraulic pressure is applied to the inner peripheral surface of the ring member from the hydraulic pressure supply source via the oil passage. Thereafter, if there is no problem such as breakage after visually checking the ring member after loading the hydraulic pressure, this ring member is used as a product. Thus, the strength of the ring member made of ceramics can be confirmed more easily than the conventional temperature raising type technique that requires press-fitting, and it can also be used for 100% inspection at the time of mass production of the ring member. The “determined oil pressure” will be described.
Prior to checking the strength of the ring member, the hoop stress against the oil pressure is calculated in advance to determine the relationship between the two, and the stress threshold is set based on the stress value at which the ring member breaks and the stress value that acts in actual operation. To do. The load oil pressure corresponding to this stress threshold is determined. The load oil pressure determined in this way is the “predetermined oil pressure”.

  You may arrange | position the oil path of the said oil pressure load seat equally in the circumferential direction several places with respect to the internal peripheral surface of a ring member. In this case, the oil pressure can be applied to the entire circumference of the inner peripheral surface of the ring member from a plurality of oil passages in the circumferential direction without deviation. Thereby, the reliability of the strength confirmation of the ring member can be further increased.

The ring member may be a ceramic inner ring of a bearing. The strength of the ceramic inner ring can be easily confirmed.
The hydraulic pressure load seat may support a bearing assembly including a ceramic inner ring on a support portion. In this case, the strength considering the rolling element load is confirmed, and the strength can be examined with a more practical stress value.

The bearing assembly may be applied to a machine tool spindle bearing.
The strength confirmation method for a ring member according to the present invention is to confirm the strength of a ring member using any strength confirmation device. By applying an oil pressure to the inner peripheral surface of the ring member whose strength is to be confirmed, a hoop stress corresponding to the oil pressure is generated in the ring member. Based on the generated hoop stress value, a threshold value on strength for use as a product can be set to evaluate hoop stress resistance.

  The strength confirmation device for a ring member according to the present invention is a strength confirmation device for confirming the strength of a ceramic ring member, and a mounted portion capable of mounting the ring member in a fitted state on an inner peripheral surface, and the mounted An oil passage is formed which has a support portion for supporting the ring member mounted on the portion and opens to face the inner peripheral surface of the ring member mounted on the mounted portion and applies hydraulic pressure to the inner peripheral surface. An oil pressure load seat, a ring member mounted on the mounted portion, a lid provided on the oil pressure load seat so as to be openable and closable, and a hydraulic pressure determined by piping connected to an oil passage of the oil pressure load seat Since it has a hydraulic pressure supply source that can be supplied to the inner peripheral surface of the ring member, the strength of the ceramic ring member can be easily confirmed, and it can also be used for 100% inspection during mass production of this ring member. .

It is sectional drawing of the intensity | strength confirmation apparatus which concerns on 1st Embodiment of this invention. It is an expanded sectional view of the principal part of the same strength confirmation apparatus. It is a figure showing the relationship between an oil pressure and generated hoop stress. It is sectional drawing of the strength confirmation apparatus which shows the example of strength confirmation by a bearing assembly.

A first embodiment of the present invention will be described with reference to FIGS.
The ring member made of ceramics subjected to strength confirmation by the strength confirmation device according to this embodiment is an inner ring of a rolling bearing. Although the below-mentioned cylindrical roller bearing is applied as an example of the rolling bearing, it is not limited to the cylindrical roller bearing. As the rolling bearing, for example, a deep groove ball bearing, an angular ball bearing, a tapered roller bearing, a self-aligning ball bearing, a thrust bearing, or the like can be applied. It is also possible to confirm the strength of the ceramic outer ring of the rolling bearing with this strength confirmation device. In addition, the following description also includes the description about the strength confirmation method of a ring member.

  As shown in FIG. 1, the strength confirmation apparatus mainly includes an oil pressure load seat 1, a lid 2, and a hydraulic pressure supply source 3. The hydraulic pressure load seat 1 is formed in a substantially cylindrical shape, and is fixed to the upper part of the base 4 or the like, for example. The hydraulic pressure load seat 1 includes a mounted portion 5, a support portion 6, and a shaft portion 7. The mounted portion 5 is composed of a cylindrical portion capable of mounting the ring member W in a fitted state on the inner peripheral surface Wa, and the support portion 6 has one side surface of the ring member W mounted on the mounted portion 5 by a clearance fit. It consists of a bearing surface part to support. The mounted portion 5 and the support portion 6 are provided by an annular step portion formed on the outer peripheral surface of the upper portion of the hydraulic pressure load seat 1. A step that forms a plane perpendicular to the axial direction in the annular step portion becomes the support portion 6, and a cylinder formed on the inner peripheral side of the support portion 6 and having a smaller diameter than the outer peripheral surface of the lower portion of the hydraulic pressure load seat 1. The portion becomes the mounted portion 5.

A shaft portion 7 fitted into the fitting hole 2 a of the lid 2 protrudes from the upper surface of the hydraulic pressure load seat 1. The shaft portion 7 is provided at the shaft center of the hydraulic pressure load seat 1. By fitting the fitting hole 2 a of the lid 2 into the shaft portion 7, the hydraulic pressure load seat 1 and the lid 2 are positioned concentrically. A chamfer 7 a is formed on the outer periphery of the tip portion of the shaft portion 7. When the fitting hole 2a of the lid 2 is fitted to the shaft portion 7, the chamfering 7a can be performed smoothly.
The lid 2 is formed in a concave cross section and covers the outer peripheral surface and the other side surface of the ring member W mounted on the mounted portion 5 and supported by the support portion 6. The lid 2 is provided on the hydraulic pressure load seat 1 so as to be freely opened and closed. A plurality of female screws 8 are formed at regular intervals in the circumferential direction at the upper part of the hydraulic pressure load seat 1, and through holes 9 corresponding to these female screws 8 are formed in the lid 2. In a state where the ring member W is mounted on the mounted portion 5 as described above, the lid 2 is closed while the fitting hole 2a of the lid 2 is fitted to the shaft portion 7, and the plurality of bolts 10 are inserted into the through holes 9. The lid 2 is fixed to the hydraulic pressure load seat 1 by being respectively screwed into the female screw 8 via.

  As shown in FIG. 2, the oil pressure load seat 1 and the lid 2 are provided with annular seal members 11, 12, and 13 each composed of an O-ring. An annular groove 14 is formed near the outer peripheral surface of the mounted portion 5 in the upper part of the hydraulic pressure load seat 1, and an annular seal member 11 is provided in the annular groove 14. The annular seal member 11 seals the mating surface 15 between the upper portion of the hydraulic pressure load seat 1 and the lower surface of the lid 2, thereby preventing oil pressure from leaking from the mating surface 15. An annular groove 16 is formed in the vicinity of the inner periphery of the support portion 6 in the hydraulic pressure load seat 1, and an annular seal member 12 is provided in the annular groove 16. An annular groove 17 is also formed near the outer periphery of the lower surface of the lid 2, and an annular seal member 13 is provided in the annular groove 17. The annular seal members 12 and 13 are arranged so as to face each other in the axial direction, and elastically support the ring member W by making contact with one side surface and the other side surface of the ring member W, respectively.

An oil passage 18 is formed in the hydraulic pressure load seat 1.
The oil passage 18 opens to face the inner peripheral surface Wa of the ring member W mounted on the mounted portion 5 and applies hydraulic pressure to the inner peripheral surface Wa. The oil passage 18 includes a first oil passage 18a extending in the axial direction from the upstream side in the oil supply direction, and a plurality of second oil passages 18b extending radially in the radial direction connected to the axial tip portion of the first oil passage 18a. And an annular groove 18c that is connected to the outer diameter end of the second oil passage 18b and extends in an annular shape. The annular groove 18c is formed in the axially intermediate portion of the outer peripheral surface of the cylindrical portion forming the mounted portion 5. The plurality of second oil passages 18b are arranged at equal circumferences.
As shown in FIG. 1, in the hydraulic pressure load seat 1, a joint member (not shown) is screwed to the base end portion of the first oil passage 18 a, and hydraulic pressure is supplied to the joint member via a pipe 19. Source 3 is connected. The hydraulic supply source 3 includes a hydraulic pump or the like.

Prior to confirming the strength of the ring member W, as shown in FIG. 3, the hoop stress with respect to the oil pressure is calculated in advance to obtain a relationship between the two, and the stress value at which the ring member W is damaged and the stress acting in actual operation A stress threshold is set based on the value. As calculation conditions, an inner ring (ring member) made of silicon nitride (Si ₃ N ₄ ), which is a structural ceramic, is used, for example, an inner ring for a cylindrical roller bearing having an inner diameter of 70 mm. The threshold value is set depending on the use application of the ceramic inner ring. If the threshold value is set higher, the reliability increases, but the yield deteriorates. On the contrary, if the threshold value is set low, the yield is improved, but the reliability is lowered. In the example of FIG. 3, the threshold value is set to about twice the practical stress value. The load oil pressure corresponding to this stress threshold is determined. If there is no problem when an oil pressure of about 40 MPa is applied to the inner peripheral surface Wa of the ring member W by the hydraulic pressure supply source 3, it can withstand a stress that is twice or more the practical value. The practical value corresponds to the generated hoop stress when a cylindrical roller bearing having an inner ring inner diameter of, for example, 70 mm is operated at 35000 min ⁻¹ .

  According to the strength checking device described above, with the lid 2 opened, the inner peripheral surface Wa of the ceramic ring member W is set to the mounted portion 5 of the hydraulic pressure load seat 1 with a clearance fit. W is supported by the support portion 6. Next, the lid 2 is closed and fixed with a plurality of bolts 10. Next, a predetermined hydraulic pressure is applied to the inner peripheral surface Wa of the ring member W from the hydraulic supply source 3 through the oil passage 18 for a predetermined time. After that, the lid 2 is opened, and the ring member W loaded with hydraulic pressure is used as a product if there is no problem such as damage by visual confirmation. As described above, the strength of the ceramic ring member W can be confirmed more easily than the conventional temperature raising type technique that requires press-fitting, and the ring member W can also be subjected to 100% inspection at the time of mass production. .

The plurality of second oil passages 18b among the oil passages 18 are arranged in a circumferentially equidistant manner, and therefore, the entire inner circumferential surface Wa of the ring member W is extended from the plurality of second oil passages 18b in the circumferential direction. The oil pressure can be applied to the circumference without any deviation. Thereby, the reliability of the strength confirmation of the ring member W can be further improved.
Further, since the annular groove 18c is connected to the outer diameter side tip portions of the plurality of second oil passages 18b and extends in an annular shape, the oil pressure applied to the inner peripheral surface Wa of the ring member W is the first and second oil passages. It is supplied to the annular groove 18c via 18a and 18b and is uniformly loaded. Thereby, the reliability of the strength confirmation of the ring member W can be further improved.

  Since the oil pressure load seat 1 and the lid 2 are provided with the annular seal members 11, 12, and 13 made of O-rings, respectively, it is possible to prevent the oil pressure from leaking out of the apparatus. As a result, the hydraulic pressure determined on the inner peripheral surface Wa of the ring member W can be reliably loaded. The annular seal members 12 and 13 are disposed so as to face each other in the axial direction, and elastically support the ring member W by making contact with one side surface and the other side surface of the ring member W, respectively. For this reason, the ring member W contacts only the annular seal members 12 and 13 without interference between the hydraulic pressure load seat 1 and the lid 2. As a result, only the oil pressure acts on the ring member W, and the reliability of the strength confirmation of the ring member W can be further increased.

FIG. 4 is a cross-sectional view of a strength confirmation device showing an example of strength confirmation by a bearing assembly.
As shown in the figure, a cylindrical roller bearing is applied as a bearing assembly. This cylindrical roller bearing includes a ceramic inner ring W1, an outer ring 20, a plurality of rolling elements 21 (rollers) interposed between the raceway surfaces of the inner and outer rings W1, 20, and these rolling elements 21 at regular intervals in the circumferential direction. And a ring-shaped cage 22 to be held in the ring. The lid 2 in this strength confirmation device covers the outer ring outer peripheral surface 20a of the cylindrical roller bearing and the entire other side surfaces of the inner and outer rings W1, 20. Other configurations are the same as those in FIGS.
In this case, the strength considering the rolling element load is confirmed, and the strength can be examined with a more practical stress value.

DESCRIPTION OF SYMBOLS 1 ... Oil pressure load seat 2 ... Lid 3 ... Hydraulic supply source 5 ... Mounted part 6 ... Supporting part 18 ... Oil path W ... Ring member Wa ... Inner peripheral surface

Claims (6)

A strength confirmation device for confirming the strength of a ceramic ring member,
The ring member has a mounted portion that can be mounted in a fitted state on an inner peripheral surface, and a support portion that supports the ring member mounted on the mounted portion. An oil pressure load seat having an oil passage that opens opposite the peripheral surface and applies hydraulic pressure to the inner peripheral surface;
A lid that covers the ring member mounted on the mounted portion and is provided on the hydraulic pressure load seat so as to be freely opened and closed;
An apparatus for confirming the strength of a ring member, comprising: a hydraulic pressure supply source capable of supplying a predetermined hydraulic pressure connected to an oil passage of the hydraulic pressure load seat to an inner peripheral surface of the ring member.   The strength confirmation device for a ring member according to claim 1, wherein oil passages of the hydraulic pressure load seat are arranged at a plurality of locations in a circumferential direction with respect to the inner circumferential surface of the ring member.   The strength confirmation device for a ring member according to claim 1 or 2, wherein the ring member is a ceramic inner ring of a bearing.   4. The ring member strength confirmation device according to claim 3, wherein the hydraulic pressure load seat is capable of supporting a bearing assembly including a ceramic inner ring in a support portion.   5. The ring member strength confirmation device according to claim 4, wherein the bearing assembly is applied to a machine tool spindle bearing.   The strength confirmation method of the ring member which confirms the intensity | strength of a ring member using the strength confirmation apparatus of any one of Claim 1 thru | or 5.

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