JP2007285480A - Rotating shaft supporting device and rotating shaft manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for improving a rolling bearing to be used for a rotating shaft supporting device while simplifying the manufacturing processes of a rotating shaft such as a ball screw shaft. <P>SOLUTION: The rotating shaft supporting device 11a comprises an outer ring 15a having an outer ring raceway 15b formed on the inner peripheral face, the ball screw shaft 3 having an inner ring raceway 15c formed on the outer peripheral face of a supporting portion 16a, and a plurality of balls 15d arranged between the outer ring raceway 15b and the inner ring raceway 15c. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotary shaft support device that rotatably supports a rotary shaft such as a ball screw shaft of a ball screw device or a central screw shaft of a planetary roller screw device, and a method for manufacturing the rotary shaft.

A rotary shaft support device for rotating and supporting a ball screw shaft of a conventional ball screw device has an inner ring of a rolling bearing in which two angular ball bearings are combined on the back surface with a support portion formed at the shaft end of the ball screw shaft. The inner ring is fastened and fixed between the stepped portion of the support portion by a lock nut that fits the peripheral surface and is screwed into a screw portion provided at the tip portion of the support portion (see, for example, Patent Document 1). ).
Further, in the rotary shaft support device for rotating and supporting the ball screw shaft of the ball screw device, the inner peripheral surface of the inner ring of the rolling bearing formed by two ball bearings on the support portion formed at the shaft end portion of the ball screw shaft The inner ring is locked between the stepped portion of the support portion by a C-type ring stopper or the like that is fitted in a locking groove provided in the circumferential direction of the distal end portion of the support portion, and the support portion A serration hole centered on the axis of the ball screw shaft is formed on the inner side of the ball screw shaft, and the driving force is transmitted by fitting the serration portion of the output shaft into the serration hole (for example, patents) Reference 2).
JP 2004-84886 (4th page, paragraph 0012-5th page, paragraph 0013, FIG. 1) JP 2002-98211 (paragraph 0021-0022, page 4, FIG. 3)

However, in the technique of the conventional patent document 1 described above, the inner ring is placed between the inner ring of the two angular ball bearings and the stepped part of the support part by a lock nut that is screwed into the screw part provided at the tip part of the support part. Since it is fastened and fixed, stress concentration occurs in the root diameter portion of the screw portion due to the tensile force when the lock nut is fastened, and the screw portion may be damaged due to fatigue.
For this reason, when performing surface quenching treatment such as carburizing quenching or induction quenching to increase the surface hardness of the shaft raceway groove of the ball screw shaft, the construction of the carburizing material before quenching and the prevention after quenching are performed. It is necessary to adjust the hardness of the area where the screw part is formed to a predetermined hardness by the anti-carbon treatment by removing the carbonaceous material or the annealing treatment after quenching, which increases the work time and man-hours in the manufacturing process of the ball screw shaft As a result, the manufacturing cost of the ball screw shaft increases.

Also, if a mounting part for mounting the coupling with the drive shaft is provided on the outer side in the axial direction of the support part, the outer diameter of the mounting part will be smaller than the diameter of the valley diameter part of the screw part for fastening the lock nut. There is a problem that the torsional strength is further insufficient.
In the technique of Patent Document 2, a serration hole is formed around the axial center of the ball screw shaft in the radial direction of the support portion to which the inner ring is fitted, and the serration portion of the output shaft is fitted into this serration hole. Because the drive torque is transmitted, the hole diameter of the serration hole is determined by the transmission torque, and the outer diameter of the support part formed on the outer side in the radial direction is also based on the shaft strength etc. based on the hole diameter of the serration hole Since the inner diameter of the inner ring of the rolling bearing that fits into the support portion needs to match the outer diameter of the support portion, there is no room for selection of the rolling bearing, and there is an unnecessary load capacity. When a rolling bearing must be used, there is a problem that the rolling bearing is enlarged and the rotating shaft support device is enlarged.

The same applies to the rolling bearing provided on the support portion of the ball screw shaft of the ball screw device when the torsional strength is insufficient.
The present invention has been made to solve the above-described problems, and provides a means for simplifying the manufacturing process of a rotating shaft such as a ball screw shaft and optimizing a rolling bearing used in the rotating shaft support device. The purpose is to do.

  In order to solve the above-described problems, the present invention provides a rotating shaft support device in which an outer ring in which an outer ring rolling element guide surface is formed on an inner peripheral surface, and a rotary shaft in which an inner ring rolling element guide surface is formed on an outer peripheral surface of a support portion; A plurality of bearing rolling elements are provided between the outer ring rolling element guide surface and the inner ring rolling element guide surface.

  Thus, according to the present invention, the inner ring rolling element guide surface of the rolling bearing is formed on the outer peripheral surface of the support portion, so that a lock nut for fixing the inner ring of the rolling bearing and a screw portion for screwing it are not required. In addition, it is possible to omit the carbon-proofing treatment and annealing treatment when performing surface hardening treatment for increasing the surface hardness of the rotating shaft, simplify the manufacturing process of the rotating shaft, and Therefore, it is possible to use a rolling bearing having an appropriate load capacity while ensuring the strength of the support portion.

  Embodiments of a rotating shaft support device and a method of manufacturing the rotating shaft according to the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing a cross section of an application example of the rotary shaft support device of the first embodiment to a ball screw device, and FIG. 2 is a view in the direction of arrow A in FIG.
In addition, the rotating shaft support device shown in FIG. 1 is shown in a cross section along the BOB cross section line of FIG.
In FIG. 1, reference numeral 1 denotes a ball screw device, which includes a ball screw shaft 3 as a rotation shaft in which an axial raceway groove 2 having an arcuate cross-sectional shape is formed in a spiral shape with a predetermined lead on the outer peripheral surface; A nut nut groove 4 having an arcuate cross-sectional shape facing the shaft raceway groove 2 on the peripheral surface is formed with the ball nut 5 formed by the same lead as the shaft raceway groove 2, and is opposed to the shaft raceway groove 2 of the ball screw shaft 3. It is formed by screwing with a ball 6 such as a rolling steel ball on a load path formed by the nut raceway groove 4 of the ball nut 5 to be rolled.

  Further, both ends of the load path are communicated by a return tube 8 to form a circulation path. The circulation path is filled with a plurality of balls 6 and a predetermined amount of lubricant, for example, grease. As the ball 6 rotates, the ball 6 circulates in the circulation path, and the ball 6 that rolls on the load path supports the load applied to the ball nut 5 in a reciprocating manner so that the ball nut 5 extends in the axial direction of the ball screw shaft 3. It is supported so that it can reciprocate linearly along. Thereby, the rotational motion of the ball screw shaft 3 is converted into the linear motion of the ball nut 5, and the ball screw device 1 functions as a linear motion device.

A flange portion 9 is provided at one end of the outer peripheral portion of the ball nut 5, and the ball nut 5 is fixed to a moving table of a mechanical device (not shown) with a bolt or the like.
The surface of the shaft raceway groove 2 of the ball screw shaft 3 of this embodiment and the surface of the nut raceway groove 6 of the ball nut 5 are relatively hard (locked) by surface quenching such as induction hardening or carburizing quenching. A hardened surface layer having a surface hardness of 50 (denoted as HrC50) or more on the C scale of well hardness is formed.

Reference numeral 11 denotes a rotating shaft support device. The rotary shaft support device 11 of the present embodiment is formed in housings 13 and 14 erected on the base 12 and is disposed at both shaft ends of the ball screw shaft 3.
The rotating shaft support device 11a disposed on one end of the ball screw shaft 3 (right side in the example of FIG. 1) has a function of rotating and supporting an axial load and a radial load simultaneously. In the embodiment, two angular ball bearings 15 as rolling bearings are arranged in a frontal combination.

  The angular ball bearings 15 arranged in the front combination include an outer ring raceway 15b serving as an outer ring rolling element guide surface which is a spherical concave surface having an arc-shaped cross section formed on the inner circumferential surface of the outer ring 15a, and one of the ball screw shafts 3, respectively. Between the inner ring raceway 15c as the inner ring rolling element guide surface, which is a spherical concave surface having an arcuate cross section formed on the outer peripheral surface of the support portion 16a formed at the shaft end of the shaft, and is freely rollable at a predetermined pitch. The outer ring 15a is fitted in the bearing fitting hole 13a of the housing 13 and is fastened to the housing 13 by the mounting bolt 17 in the axial direction. Pressed and fixed.

The angular ball bearing 15 may be provided with a cage that holds the balls 15d at an equiangular pitch.
As a result, preload is applied to the angular ball bearing 15 of the front combination, the ball 15d is sandwiched between the outer ring raceway 15b and the inner ring raceway 15c at a predetermined contact angle, and the ball screw shaft 3 has its axial load and radial direction. It is supported rotatably while being supported by the load.

Reference numeral 19 denotes an oil seal, which is arranged on both sides of the front combination angular ball bearing 15, and its lip portion is in sliding contact with the outer peripheral surface of the support portion 16a to prevent leakage of lubricant from the inside of the rotary shaft support device 11a. In addition, the entry of foreign matter from the outside is prevented.
The rotating shaft support device 11b arranged at the other shaft end of the ball screw shaft 3 (left side in the example of FIG. 1) mainly has a function of rotating and supporting a radial load. It is formed by a deep groove type ball bearing 21 as a bearing.

  The ball bearing 21 is formed on the outer ring raceway groove 21b as an outer ring rolling element guide surface which is a spherical concave surface having an arc-shaped cross section formed on the inner peripheral surface of the outer ring 21a and the other shaft end of the ball screw shaft 3. Between the inner ring raceway groove 21c as the inner ring rolling element guide surface, which is a spherical concave surface having an arc-shaped cross section formed on the outer peripheral surface of the support portion 16b, and is freely rollable to a cage (not shown) at a predetermined angular pitch. The outer ring 21a is fitted and attached to the bearing fitting hole 14a of the housing 14, and includes a plurality of outer ring raceway grooves 21b and inner ring raceway grooves 21c. The ball screw shaft 3 is rotatably supported by the balls 15d rolling between the balls 15d while supporting the radial load.

Reference numeral 23 denotes an attachment portion which is connected to a drive shaft from a drive device such as a motor (not shown) for rotating the ball screw shaft 3 rotatably supported by the rotation shaft support devices 11a and 11b disposed on the support portions 16a and 16b. In order to attach a coupling for this purpose, a cylindrical portion is provided coaxially on the outer side in the axial direction of the support portion 16a of the ball screw shaft 3.
The ball screw shaft 3 is manufactured as follows.

  That is, the outer peripheral surface of a cylindrical round bar made of a steel material such as alloy steel or a cylindrical pipe member is left with a finishing allowance for the shaft raceway groove 2 and a finishing allowance for the inner ring raceway 15c and the inner ring raceway groove 21c. The surface of the shaft material is hardened by a surface hardening process such as carburizing and induction hardening to form a hardened surface layer having a surface hardness of HrC50 or more. The inner ring raceway 15c and the inner ring raceway groove 21c are finished by cutting or grinding to form the ball screw shaft 3.

  Thus, in the manufacturing process in which the inner ring raceway 15c and the inner ring raceway groove 21c of the present embodiment are formed integrally with the ball screw shaft 3, the removal of the carburizing material after the surface quenching process or the annealing process may be omitted. In addition, the shaft raceway groove 2 of the ball screw shaft 3, and the inner ring raceway 15c and the inner ring raceway groove 21c can be finished with one chuck, and the inner ring raceway 15c with respect to the shaft raceway groove 2 can be compared with the case where the inner ring is fitted. And the precision of the coaxiality of the inner ring raceway groove 21c can be improved.

  As described above, the inner ring raceway 15c of the angular ball bearing 15 and the inner ring raceway groove 21c of the ball bearing 21 as the inner ring rolling element guide surface of the rolling bearing of the present embodiment are respectively provided in the support portions 16a and 16b of the ball screw shaft 3. Since they are integrally formed, a lock nut for fixing the inner ring of the angular ball bearing 15 and a threaded portion for screwing it are unnecessary, and the surface hardness of the shaft raceway groove 2 of the ball screw shaft 3 is increased. In addition to reducing the manufacturing cost by reducing the working time and man-hours in the manufacturing process of the ball screw shaft 3, it is possible to omit the charcoal-proofing and annealing processes when performing the surface quenching process. Since there is no threaded portion for fastening the lock nut, the ball screw shaft 3 can be prevented from being damaged by fatigue and the overall length of the ball screw shaft 3 can be shortened. It can be.

In addition, since the lock nut is unnecessary, the number of parts can be reduced to improve the reliability of the ball screw device 1 and the manufacturing cost and reduction of the ball screw device 1 can be achieved.
Further, since it is not necessary to form a screw portion for fastening the lock nut, the outer peripheral surface of the support portions 16a and 16b is used as it is as the outer peripheral surface of the attachment portion 23. In addition to being able to ensure sufficient torsional strength, an unnecessary load capacity can be secured to ensure the strength of the support portions 16a and 16b to which the inner peripheral surface of the inner ring is fitted. When a rolling bearing is used, the inner ring rolling element guide surface can be formed on the outer peripheral surfaces of the support portions 16a and 16b, so that the rolling force has an appropriate load capacity while ensuring the strength of the support portions 16a and 16b. A bearing can be used, and the rotating shaft support device 11 can be downsized.

Since the rotary shaft support device 11b does not require the ball screw shaft 3 to be restrained in the axial direction, a lock nut is unnecessary, and there is no need to form a threaded portion for this purpose. You may make it use a bearing retrofitted.
As described above, in this embodiment, the inner ring raceway and the inner ring raceway groove of the rotating shaft support device of the ball screw shaft of the ball screw device are formed on the outer peripheral surface of the support portion of the ball screw shaft. There is no need for a lock nut for fixing the inner ring of the rolling bearing or a threaded portion for screwing it, and a carburizing process for surface hardening treatment to increase the surface hardness of the shaft raceway groove of the ball screw shaft. The annealing process can be omitted, the manufacturing process of the ball screw shaft can be simplified, and it is not necessary to fit the inner ring to the support part. Can be used.

In addition, the ball screw shaft is formed by cutting a shaft material having a surface hardness of HrC50 or higher, so that the shaft raceway groove of the ball screw shaft and the inner ring rolling element guide surface of the rolling bearing can be formed with one chuck. It is possible to finish, and the accuracy of the coaxiality of the inner ring rolling element guide surface with respect to the shaft raceway groove can be improved.
In this embodiment, the case where the present invention is applied to a ball screw device using a tube-type circulation system that circulates a ball by a return tube has been described as an example, but a top type, an end cap type, a deflector type, etc. Even if the present invention is applied to the circulation type ball screw device, the same effect can be obtained.

FIG. 3 is an explanatory view showing a cross section of an application example of the rotating shaft support device of the second embodiment to a planetary roller screw device.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
In FIG. 3, reference numeral 31 denotes a planetary roller screw device, which includes a central screw shaft 33 as a rotating shaft in which a shaft screw 32 having a trapezoidal cross-sectional shape thread on the outer peripheral surface is formed at a predetermined pitch, and a cylindrical member. A multi-threaded nut screw 34 having a thread having the same shape as that of the shaft screw 32 on the inner peripheral surface and having a twist opposite to that of the shaft screw 32 is formed on the roller nut 35 having the same pitch P as that of the shaft screw 32. One roller screw 36 having the same shape as that of the shaft screw 32 on the surface and having a twist in the same direction as the nut screw 34 is formed at the same pitch P as that of the shaft screw 32. It is formed by fitting a planetary roller 38 on which 37 is formed.

  The planetary roller 38 is rotatably held by a roller holder 40 in which both projecting shaft portions 37 are restricted from moving in the axial direction by a retaining ring 39 locked to the inner peripheral surface of the roller nut 35. A planetary pinion gear 41 formed coaxially with the planetary roller 38 between the projection shaft portion 37 and the roller screw 36 is engaged with a ring gear 43 fixed by a pin 42 inside the roller nut 35, and the central screw shaft 33 is engaged. Is rotated, the planetary roller 38 held by the roller holder 40 revolves around the central screw shaft 33 by the planetary pinion gear 41 meshed with the ring gear 43, and is fixed to a moving table of a mechanical device (not shown). The rolled roller nut 35 is linearly reciprocated in the axial direction within the formation range of the shaft screw 32. Thereby, the rotational motion of the central screw shaft 33 is converted into the linear motion of the roller nut 35, and the planetary roller screw device 31 functions as a linear motion device.

The surface of the shaft screw 32 of the central screw shaft 33, the nut screw 34 of the roller nut 35, and the roller screw 36 of the planetary roller 38 of the present embodiment has a relatively high surface hardness (HrC50 or more) by surface hardening treatment. A surface hardened layer is formed.
45 is a rotating shaft support device. The rotary shaft support device 45 of this embodiment is formed in a housing 46 fixed to a frame or the like of a mechanical device (not shown), and is disposed at one shaft end of the central screw shaft 33.

Similar to the rotary shaft support device 11a of the first embodiment, the rotary shaft support device 45 of the present embodiment has a function of rotating and supporting an axial load and a radial load at the same time. Similarly to the first embodiment, two angular ball bearings 15 as rolling bearings are arranged in a front combination.
In the angular ball bearing 15 of this embodiment, an inner ring raceway 15 c as an inner ring rolling element guide surface is formed on the outer peripheral surface of a support portion 47 formed at one shaft end of the shaft screw 32.

  Further, each outer ring 15a is fitted into a bearing fitting hole 46a of the housing 46, and is pressed and fixed in the axial direction by a lid body 48 fastened to the housing 46 by a mounting bolt (not shown). A preload is applied to the angular ball bearing 15, the ball 15d is held at a predetermined contact angle between the outer ring raceway 15b and the inner ring raceway 15c, and the central screw shaft 33 is supported by the axial load and the radial load. It is supported rotatably.

The central screw shaft 33 is manufactured as follows.
That is, a shaft material obtained by machining the outer peripheral surface of a columnar round bar material or a cylindrical pipe material made of a steel material such as alloy steel, leaving the finishing allowance of the shaft screw 32 and the finishing allowance of the inner ring raceway 15c. The surface of the shaft material is hardened by surface hardening treatment to form a hardened surface layer having a surface hardness of HrC50 or more, and the center screw shaft and the inner ring raceway 15c are finished by cutting or grinding. 33 is formed.

  Thus, in the manufacturing process in which the inner ring raceway 15c of this embodiment is formed integrally with the central screw shaft 33, the removal of the carburizing material after the surface quenching process or the annealing process can be omitted, and the central screw The shaft screw 32 of the shaft 33 and the inner ring raceway 15c can be finished with one chuck, and the accuracy of the coaxiality of the inner ring raceway 15c with respect to the shaft screw 32 can be improved as compared with the case where the inner ring is fitted.

  As described above, the inner ring raceway 15c of the angular ball bearing 15 of the present embodiment is integrally formed with the support portion 47 of the central screw shaft 33, so that a lock nut for fixing the inner ring of the angular ball bearing 15 is provided. And a screw portion for screwing them is unnecessary, and the carbonization prevention treatment and annealing treatment when performing surface hardening treatment for increasing the surface hardness of the shaft screw 32 of the central screw shaft 33 can be omitted. In addition to reducing the working time and man-hours in the manufacturing process of the screw shaft 33 and reducing the manufacturing cost, there is no thread portion for fastening the lock nut that causes stress concentration. Breakage can be prevented and the total length of the central screw shaft 33 can be shortened.

Further, since the lock nut is unnecessary, the number of parts can be reduced to improve the reliability of the planetary roller screw device 31, and the manufacturing cost and reduction of the planetary roller screw device 31 can be achieved.
Further, since it is not necessary to form a screw portion for fastening the lock nut, the outer peripheral surface of the support portion 47 is used as it is as the outer peripheral surface of the attachment portion 23. That is, the support portion 47 has the function of the attachment portion 23 of the first embodiment. In addition to being able to easily ensure sufficient torsional strength, a rolling bearing with an unnecessary load capacity is required in order to ensure the strength of the support portion 47 to which the inner peripheral surface of the inner ring is fitted. Since the inner ring raceway 15c can be formed on the outer peripheral surface of the support portion 47, the angular ball bearing 15 having an appropriate load capacity can be used while ensuring the strength of the support portion 47. Thus, it is possible to reduce the size of the rotary shaft support device 45.

  As described above, the inner ring raceway of the rotating shaft support device of the central screw shaft of the planetary roller screw device is formed on the outer peripheral surface of the support portion of the central screw shaft, and the same as in the first embodiment. An effect can be obtained.

FIG. 4 is an explanatory view showing a cross section of an application example of the rotating shaft support device of the third embodiment to a planetary roller screw device.
In addition, the same part as the said Example 1 and Example 2 attaches | subjects the same code | symbol, and abbreviate | omits the description.
In FIG. 4, reference numeral 51 denotes a planetary roller screw device. A shaft screw 52 similar to that of the second embodiment has a central screw shaft 53 as a rotation shaft formed on the other shaft end, and a nut screw similar to that of the second embodiment. 54 is formed by fitting a roller nut 56 formed over the entire length of the inner peripheral surface with the same roller screw 56 and the planetary roller 58 formed with the protruding shaft portion 57 as in the second embodiment.

  The planetary roller 58 is rotatably held by a roller holder 60 whose both projecting shaft portions 57 are restricted in axial movement by a retaining ring 59 that is locked to the outer peripheral surface of the central screw shaft 53. A planetary pinion gear 61 formed coaxially with the planetary roller 58 between the protruding shaft portion 57 and the roller screw 56 is engaged with a ring gear 63 fixed to the outer peripheral surface of the central screw shaft 53, and the central screw shaft 53 is When rotated, the planetary roller 58 held by the roller holder 60 revolves around the central screw shaft 53 by the planetary pinion gear 61 meshed with the ring gear 63, and is fixed to a moving table of a mechanical device (not shown). The roller nut 55 is linearly reciprocated in the axial direction within the range where the nut screw 54 is formed. Thereby, the rotational motion of the central screw shaft 53 is converted into the linear motion of the roller nut 55, and the planetary roller screw device 51 functions as a linear motion device.

The surface of the shaft screw 52 of the central screw shaft 53, the nut screw 54 of the roller nut 55, and the roller screw 56 of the planetary roller 58 of this embodiment has a surface hardness of a relatively high hardness (HrC50 or more) by surface hardening treatment. A surface hardened layer is formed.
Reference numeral 65 denotes a rotating shaft support device. The rotary shaft support device 65 of this embodiment is formed in a housing 66 fixed to a frame or the like of a mechanical device (not shown), and is disposed at one shaft end portion of the central screw shaft 53.

  The rotary shaft support device 65 of this embodiment has a function of simultaneously rotating and supporting an axial load and a radial load. In this embodiment, one of the angular ball bearing 15 as a rolling bearing and the central screw shaft 53 is provided. One thrust receiving surface 68a is an end surface on the outer side in the axial direction of the support portion 67 formed at the shaft end portion, that is, a plane extending in the radial direction of the central screw shaft 53 on the outer side in the axial direction of the support portion 67. It is formed in combination with a thrust needle bearing 68 as a thrust bearing.

In the angular ball bearing 15 of this embodiment, an outer ring raceway 15 b as an outer ring rolling element guide surface is formed on the inner peripheral surface of the housing 66, and an inner ring raceway 15 c as an inner ring rolling element guide surface is one of the shaft screws 52. It is formed in the outer peripheral surface of the support part 67 formed in the axial end part.
The lid 69 is formed with the other thrust receiving surface 68b opposite to the thrust receiving surface 68a formed on the end surface of the support portion 67, and the needles are formed at a predetermined pitch between these thrust receiving surfaces 68a and 68b. A plurality of needles 68d that are rotatably held by the cage 68c are disposed. When the lid body 69 is fastened to the housing 66 by a mounting bolt (not shown), a preload is applied to the angular ball bearing 15, 15d is sandwiched between the outer ring raceway 15b and the inner ring raceway 15c with a predetermined contact angle, the needle 68d is sandwiched between the thrust receiving surfaces 68a and 68b by preload, and the central screw shaft 53 is It is supported rotatably while being supported by a radial load.

  As described above, the rotary shaft support device 65 of the present embodiment is formed by combining the angular ball bearing 15 and the thrust needle bearing 68, and therefore the planetary roller screw device 51 used for clamping the electric injection molding machine. Thus, when a large axial load is applied in one direction (from the right to the left in FIG. 4 and the thrust needle bearing 68 is pressed) and the reverse axial load is not so large, the load direction is adapted. Can be configured.

Further, since the axial rigidity of the angular ball bearing 15 is smaller than the axial rigidity of the thrust needle bearing 68, the interval setting for applying an appropriate preload is set compared to the case where the thrust needle bearings 68 are arranged on both sides. It becomes possible to carry out easily.
This is the same even when the rotary shaft support device 65 of this embodiment is applied to the ball screw shaft 3 of the ball screw device 1 of the first embodiment and the central screw shaft 33 of the planetary roller screw device 31 of the second embodiment. It is.

The central screw shaft 53 is manufactured as follows.
That is, a shaft material is formed by processing the outer peripheral surface of a cylindrical round bar made of a steel material such as alloy steel while leaving the finishing allowance of the shaft screw 52 and the finishing allowance of the inner ring raceway 15c and the thrust receiving surface 68a. Then, the surface of the shaft material is cured by a surface quenching process to form a surface hardened layer having a surface hardness of HrC50 or higher, and the shaft screw 52, the inner ring raceway 15c and the thrust receiving surface 68a are finished by cutting or grinding. A central screw shaft 53 is formed.

  Thus, in the manufacturing process in which the inner ring raceway 15c and the thrust receiving surface 68a of the present embodiment are formed integrally with the central screw shaft 53, the removal of the carbon-proof material after the surface quenching process or the annealing process may be omitted. In addition, the shaft screw 52 of the central screw shaft 53, the inner ring raceway 15c and the thrust receiving surface 68a can be finished with a single chuck, and the inner ring raceway 15c is coaxial with the shaft screw 52 as compared with the case where the inner ring is fitted. The accuracy of the degree can be improved, and the accuracy of the perpendicularity of the thrust receiving surface 68a with respect to the shaft screw 52 can be improved.

  As described above, the inner ring raceway 15c of the angular ball bearing 15 of the present embodiment is formed integrally with the support portion 67 of the central screw shaft 53, and therefore, a lock nut for fixing the inner ring of the angular ball bearing 15 or the like. A screw portion for screwing this is not necessary, and it is possible to omit a charcoal-proofing treatment and an annealing treatment when performing a surface hardening treatment for increasing the surface hardness of the shaft screw 52 of the central screw shaft 53. In addition to reducing the manufacturing cost by reducing the working time and man-hours in the manufacturing process of the shaft 53, there is no thread portion for fastening the lock nut that causes stress concentration, so the central screw shaft 53 is damaged due to fatigue. And the overall length of the central screw shaft 53 can be shortened.

Further, since the lock nut is unnecessary, the number of parts can be reduced to improve the reliability of the planetary roller screw device 51, and the manufacturing cost and reduction of the planetary roller screw device 51 can be achieved.
Further, when a rolling bearing with an unnecessary load capacity is used to secure the strength of the support portion 67 to which the inner peripheral surface of the inner ring is fitted, the inner ring raceway 15c is formed on the outer peripheral surface of the support portion 67. Therefore, the angular ball bearing 15 having an appropriate load capacity while ensuring the strength of the support portion 67 can be used, and the rotating shaft support device 65 can be downsized.

As described above, in this embodiment, in addition to the same effects as those of the second embodiment, the thrust receiving surface of the thrust needle bearing is formed at the shaft end of the central screw shaft, so that a large shaft in one direction can be obtained. When a lateral load is applied and the axial load in the reverse direction is not so large, a configuration suitable for the load direction can be obtained.
This is particularly effective in the case of a mechanical device that applies a large axial load only in one direction, such as an electric injection molding machine.

  In the present embodiment, the thrust bearing is described as being a thrust needle bearing. However, the thrust bearing is not limited to the above, and may be a thrust roller bearing or a thrust ball bearing.

FIG. 5 is an explanatory view showing a cross section of an application example of the rotary shaft support device of the third embodiment to a planetary roller screw device.
In addition, the same part as the said Example 1 and Example 2 attaches | subjects the same code | symbol, and abbreviate | omits the description.
The planetary roller screw device and the rotary shaft support device of the present embodiment are the same as the planetary roller screw device 31 and the rotary shaft support device 45 of the second embodiment, but on the end surface of one shaft end of the central screw shaft 33. A different point is that a coupling mounting hole 71 is formed centering on the axis of the central screw shaft 33 and extending inward in the radial direction of the inner ring raceway 15 c formed in the support portion 47.

In this coupling attachment hole 71, one end is fixed to the bottom surface of the coupling attachment hole 71, and the other end connected via a plurality of leaf springs 73 is indicated by a two-dot chain line in FIG. A flexible coupling 76 fixed to a shaft 75 (for example, a drive shaft to which a driving force from a driving device such as a motor is transmitted) is accommodated.
As such a flexible coupling 76, for example, a flexible coupling using a deflection of a leaf spring 73 such as a servo flex coupling SFC-SA2 manufactured by Miki Pulley Co., Ltd. can be used.

As described above, since the central screw shaft 33 and the mating shaft 75 of this embodiment are connected via the flexible coupling 76, it is possible to absorb the misalignment between the central screw shaft 33 and the mating shaft 75. become.
Further, since the inner ring raceway 15c of this embodiment is directly formed on the outer peripheral surface of the support portion 47 of the central screw shaft 33, the diameter of the support portion 47 can be expanded to the bottom diameter of the inner ring raceway 15c. A machine having a planetary roller screw device 31 that can accommodate a coupling having a relatively large outer diameter, such as the flexible coupling 76, in a coupling mounting hole 71 provided radially inward of the support portion 47. The space required for connection with the drive shaft of the apparatus can be reduced, and the mechanical apparatus can be reduced in size.

  Furthermore, when connecting with the drive shaft of the mechanical device by serration with a relatively small outer diameter, it is possible to form serration on the inner surface of the coupling mounting hole 71 having a smaller diameter and fit the serration shaft therewith. Thus, when a rolling bearing having an unnecessary load capacity is used to secure the strength of the serration shaft and the strength of the support portion 47, the rolling bearing having an appropriate load capacity while ensuring the strength of the support portion 47. Thus, it is possible to reduce the size of the rotating shaft support device 31.

In addition, since the manufacturing method of the center screw shaft 33 of a present Example is the same as that of the said Example 2, the description is abbreviate | omitted.
As described above, in this embodiment, in addition to the same effects as those of the second embodiment, the end surface of the shaft end portion of the center screw shaft is centered on the axis of the center screw shaft, and the radial direction of the inner ring raceway is increased. Coupling with a relatively large diameter can be accommodated in the coupling mounting hole by using the enlarged support, and a planetary roller screw device is installed. In addition to reducing the size of the mechanical device, when using a relatively large diameter coupling, the load capacity of the rolling bearing can be optimized to reduce the size of the rotating shaft support device.

In the first, second, and fourth embodiments, the angular ball bearings 15 are described as being arranged in the front combination, but may be arranged in the rear combination as shown in FIG. In this case, the rotating shaft support device 11a of Example 1 is formed as follows.
That is, a circumferential groove 81 in which inner ring raceways 15 c are formed on both side walls is provided on the outer peripheral surface of the support portion 16 a, an outer ring 82 in which two outer ring raceways 15 b are formed on the back side is formed, and the outer ring 82 is circumferential groove 81. And a predetermined number of balls 15d are inserted from both sides between the inner ring raceway 15c and the outer ring raceway 15b expanded by the eccentricity, and the outer ring 82 and the circumferential groove 81 are returned to concentricity after the insertion. Then, the bearing cage 83 is assembled to form the angular ball bearing 15 arranged in the rear combination. The same applies to the central screw shaft 33 of the second and fourth embodiments.

In each of the above embodiments, the rolling bearing has been described as an angular ball bearing or a deep groove type ball bearing using a ball as a bearing rolling element. However, the rolling bearing is not limited to the above, and a roller is used as the bearing rolling element. A cylindrical roller bearing or a tapered roller bearing may be used. In this case, the inner ring rolling element guide surface is the inner ring raceway cylindrical surface of the cylindrical roller bearing and the inner ring raceway conical surface of the tapered roller bearing.
In each of the above embodiments, the rotation shaft is described as the ball screw shaft of the ball screw device or the central screw shaft of the planetary roller screw device. However, the rotation shaft is not limited to the above, and the slide screw shaft of the slide screw device. Further, it may be a serration shaft or a spline shaft that rotatably supports a pulley, a gear, or the like.

Explanatory drawing which shows the cross section of the example of application to the ball screw apparatus of the rotating shaft support apparatus of Example 1. FIG. 1. A direction arrow view of FIG. Explanatory drawing which shows the cross section of the example of application to the planetary roller screw apparatus of the rotating shaft support apparatus of Example 2. FIG. Explanatory drawing which shows the cross section of the example of application to the planetary roller screw apparatus of the rotating shaft support apparatus of Example 3. FIG. Explanatory drawing which shows the cross section of the example of application to the planetary roller screw apparatus of the rotating shaft support apparatus of Example 4. FIG. Explanatory drawing which shows the other form of the angular ball bearing used for the rotating shaft support apparatus of Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ball screw apparatus 2 Axis raceway groove 3 Ball screw shaft 4 Nut raceway groove 5 Ball nut 6 Ball 8 Return tube 9 Flange part 11, 11a, 11b, 45, 65 Rotary shaft support apparatus 12 Base 13, 14, 46, 66 Housing 13a, 14a, 46a, 66a Bearing fitting hole 15 Angular contact ball bearings 15a, 21a, 82 Outer ring 15b Outer ring raceway 15c Inner ring raceway 15d, 21d Balls 16a, 16b, 47, 67 Support part 17 Mounting bolt 18, 48, 69 Lid Body 19 Oil seal 21 Ball bearing 21b Outer ring raceway groove 21c Inner ring raceway groove 23 Mounting portion 31, 51 Planetary roller screw device 32, 52 Shaft screw 33, 53 Central screw shaft 34, 54 Nut screw 35, 55 Roller nut 36, 56 Roller Screw 37, 57 Projection shaft 38, 58 Planetary roller 39 59 Retaining ring 40, 60 Roller retainer 41, 61 Planetary pinion gear 42 Pin 43, 63 Ring gear 68 Thrust needle bearing 68a, 68b Thrust receiving surface 68c Needle retainer 68d Needle 71 Coupling mounting hole 73 Plate spring 74 Clamp bolt 75 Opposite shaft 76 Flexible coupling 81 Circumferential groove 83 Bearing cage

Claims (7)

  An outer ring having an outer ring rolling element guide surface formed on the inner peripheral surface, a rotary shaft having an inner ring rolling element guide surface formed on the outer peripheral surface of the support portion, and the outer ring rolling element guide surface and the inner ring rolling element guide surface. A rotating shaft support device comprising a plurality of bearing rolling elements provided. In claim 1,
The rotary shaft support device, wherein the rotary shaft is a ball screw shaft of a ball screw device. In claim 1,
The rotary shaft support device, wherein the rotary shaft is a central screw shaft of a planetary roller screw device. In any one of Claims 1 to 3,
A rotating shaft support device, wherein a thrust receiving surface of a thrust bearing extending in a radial direction of the rotating shaft is formed at a shaft end portion of the rotating shaft. In any one of Claims 1 to 3,
The inner ring rolling element guide surface is formed on the outer peripheral surface of the shaft end portion of the rotating shaft, and the end surface of the shaft end portion is centered on the axis of the rotating shaft and is in the radial direction of the inner ring rolling element guide surface. A rotating shaft support device, characterized in that a coupling mounting hole is formed to reach the inside. In any one of Claims 1 thru | or 5,
A rotating shaft support device, wherein the rotating shaft is formed by cutting a shaft material of the rotating shaft having a surface hardness of HrC50 or higher. It is a manufacturing method of the rotating shaft of the rotating shaft support device according to any one of claims 1 to 5,
Performing a surface quenching treatment on the shaft material of the rotating shaft with a surface hardness of HrC50 or higher;
And a step of forming the inner ring rolling element guide surface on the shaft material that has been subjected to the surface hardening process by cutting.