JP2010121649A - Self-aligning ball bearing with cage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase efficiency in assembling work, by facilitating work for click-fitting a ball 3 to a pocket 9 of a cage 4, in a self-aligning roller bearing with the cage. <P>SOLUTION: When click-fitting the ball 3 from the side by arranging a constructed part 12 having a thinner width than a width of a column part 8 in a ball slipping-out preventive part 10, in the column part 8 on the rim part side more than the ball slipping-out preventive part 10 formed on a side surface of the adjacent column parts 8 of the cage 4, the column part 8 is easily deflected in the expanding direction by the constricted part 12, and the ball 3 can be easily stored between the adjacent column parts 8. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a self-aligning ball bearing with a cage. Self-aligning ball bearings with cages are formed so that the race of the outer ring is spherical and the center of curvature coincides with the center of the bearing, so the inner ring, balls, and cage rotate freely around the bearing center. It is used in places where the shaft and housing are difficult to align and where the shaft is difficult to align and the shaft is flexible.

  As a self-aligning ball bearing with a cage, one having a structure shown in FIG. 9 is conventionally known. In this self-aligning ball bearing with a cage, a plurality of balls 33, 33 are arranged to roll freely between an outer ring 31 and an inner ring 32 that are concentrically combined with each other. The cage 34 prevents the balls 33 from coming out even when the inner ring 32, the balls 33, and the cage 34 are freely rotated around the center of the bearing.

  As shown in FIG. 10, an outer ring raceway 35 which is a spherical concave surface having a single center is formed on the inner peripheral surface of the outer ring 31. A pair of inner ring raceways 36 and 36 are formed on the outer peripheral surface of the inner ring 32 so as to face the outer ring raceway 35.

  As shown in FIGS. 10 and 11, the retainer 34 has an annular rim portion 37 disposed between the balls 33, 33 in both rows, and outer peripheral edges on both side surfaces of the rim portion 37. And a column portion 38 that protrudes in the axial direction and is arranged at equal intervals, and holds the ball 33 between the column portions 38 adjacent to each other in the circumferential direction on the side surfaces of the rim portion 37 so as to be able to roll. 39, the distance between the adjacent pillars 38, 38 on the front end side is narrower than the diameter of the ball 33 accommodated in the pocket 39, and the ball retaining portion 40 that prevents the ball 33 from slipping off in the axial direction side of the pocket 39. Is formed on the side surface of the column portion 38. Further, on the inner diameter side of the annular rim portion 37, an auxiliary column portion 41 is provided corresponding to each column portion 38 so that adjacent balls 33 do not interfere with each other.

  As shown in FIG. 12, the retainer 34 is formed by bending a punched metal plate 44. The retainer 34 is formed by forming a column portion 38, 38 on the outer diameter side of the annular rim portion 37, and on the inner diameter side. After the portions that form the auxiliary column portions 41 are aligned and the metal plate 44 is punched, the portions that form the outer diameter side column portions 38 and 38 and the portions that form the inner diameter side auxiliary column portions 41 are The ring-shaped rim portion 37 is bent around the ring rim portion 37 so as to be alternately arranged on both sides thereof, and formed into a shape as shown in FIG. In FIG. 12, the folding directions of the column portion 38 and the auxiliary column portion 41 are indicated by arrows F and G. The arrow F points in the opposite direction to the direction toward the front of the page, and G indicates the direction opposite to the sheet. .

  The self-aligning roller bearing with a cage having the above structure is used with the outer ring 31 fitted and fixed to the housing and the inner ring 32 fitted and fixed to the rotary shaft, for example, when the rotary shaft is supported inside the housing. When the inner ring 32 rotates together with the rotation shaft, the plurality of ball rollers 33 and 33 roll to allow this rotation. When the axis of the housing and the axis of rotation of the housing are misaligned, the inner ring 32 is aligned inside the outer ring 31 by tilting the central axis of the inner ring 32 with respect to the central axis of the outer ring 31. Has been fixed. In this case, since the outer ring raceway 35 is formed in a single spherical shape, the rolling of the plurality of ball rollers 33, 33 is smoothly performed even after the deviation correction.

  By the way, when assembling the self-aligning roller bearing with a cage having the above structure, first, as shown in FIG. 13, with the cage 34 fitted on the outer periphery of the inner ring 32, as shown in FIG. A ball 33 is inserted between the matching column portions 38 and 38 from the side, and the ball 33 is accommodated in each pocket 39 of the cage 4. When the balls 33 are accommodated in the respective pockets 39, the balls 33 are axially arranged by three points of the ball retaining portions 40 of the adjacent pillar portions 38 and 38 and the outer walls of the inner ring raceways 36 and 36 of the inner ring 32. The outside is prevented from coming off.

  As described above, the balls 33 are stored in the respective pockets 39 of the cage 34 by inserting the balls 33 between the adjacent column portions 38 and 38 from the side as shown in FIG. In the case where the allowance between the pillars 38 and 38 is large, a large force is required, and the assembly work takes time and the assembly worker slips his hand excessively when the click is inserted. There is a risk that the hand is injured by the pillar portion 38.

  Further, since the conventional cage 34 is formed by bending a punched metal plate as described above, as shown in the enlarged view of FIG. 15 in which the portion surrounded by the arrow H in FIG. The side surface of the portion 38 has an angular shape with a punched cross section. For this reason, there is a possibility that the corner of the pillar portion 38 hits the ball 33 and damages the ball 33. Further, the lubricating oil is scraped off at the corner portion, and there is a possibility that the lubrication performance is deteriorated.

  Furthermore, when each pillar part 38 and the ball | bowl 33 hit the corner, there also existed a problem that the stability of the ball | bowl 33 in each pocket 39 lacked.

  Therefore, the present invention facilitates the insertion of the balls 33 into the respective pockets 39 of the retainer 34 by facilitating the insertion of the balls 33 from the side between the adjacent column portions 38, 38, and the efficiency of the assembly work. The technical challenge is to make it easier.

  Moreover, this invention makes it another technical subject to prevent the injury of the worker in the time of a claw insertion work.

  Further, the present invention has another technical problem to improve the lubrication performance of the balls 33, improve the stability of the balls 33 in each pocket 39, and enable higher speed operation. It is.

  First, in order to make it easier to catch a ball from the side between adjacent column portions, the present invention prevents the ball from being removed from the ball portion on the rim side of the ball removal preventing portion formed on the side surface of the adjacent column portion. A configuration is adopted in which a narrow portion narrower than the width of the column portion is provided.

  In this way, if a narrower portion narrower than the width of the pillar part in the ball retaining part is provided in the pillar part closer to the rim part than the ball retaining part, the ball is clicked from the side between adjacent pillar parts. When inserting, it bends in the direction which a pillar part spreads in a constriction part, and a ball can be easily accommodated between adjacent pillar parts.

  Next, this invention employ | adopted the structure that the inclination guide which the pocket space | interval between adjacent pillar parts spreads is provided in the front end side part from the ball drop prevention part of the pillar part.

  In this way, when an inclined guide that increases the pocket interval between adjacent column portions is provided on the tip side portion from the ball retaining portion of the column portion, when the balls are clicked from the side between the adjacent column portions, Since the ball hits the inclined guide at the tip of the pillar part, when the ball is pushed in as it is, the neighboring pillar parts spread each other by the inclined guide, the ball gets over the ball retaining part of the pillar part, and the ball enters the pocket between the pillar parts. Fits easily.

  Next, the present invention employs a configuration in which both side surfaces of the column part are inclined surfaces in which a pocket interval between adjacent column parts is narrowed from the inner diameter side toward the outer diameter side.

  As described above, when the side surface of the column part is an inclined surface in which the pocket interval between the adjacent column parts is narrowed from the inner diameter side toward the outer diameter side, the side surface of the column part is inclined in a direction along the arc surface of the ball. Therefore, the corner portion of the pillar portion does not hit the ball, the scraping of the lubricating oil can be prevented, and the ball can be accommodated in the pocket in a stable state.

  Further, the present invention employs a configuration in which the side surface of the column part is formed on an arc surface opposite to the direction of the arc of the ball accommodated between the pockets between adjacent column parts.

  In this way, by forming the side surface of the column portion on an arc surface opposite to the direction of the arc of the ball accommodated between the pockets between adjacent column portions, the corner portion of the column portion hits the ball. The ball arc and the arc in the opposite direction of the column part can create a lubricating oil reservoir on both sides of the contact part between the ball and the column part, improving the lubrication effect and preventing damage to the ball it can. In addition, since the contact area between the ball and the column is small, the contact resistance is suppressed, and the torque is reduced, so that higher speed operation is possible.

  Moreover, this invention can also form both the side surfaces of the said pillar part in the circular arc surface of the same direction as the direction of the circular arc of the ball accommodated between the pockets between adjacent pillar parts.

  As described above, when both side surfaces of the column part are formed on the arc surface having the same direction as the arc of the ball accommodated between the pockets between the adjacent column parts, the behavior of the ball in the pocket is stabilized. By making the curvature radius of this arc surface larger than the curvature radius of the ball, contact between the outer diameter side and inner diameter side corners of the column and the ball is prevented, and damage to the ball is prevented. Can do. Furthermore, in order to prevent contact between the outer diameter side and inner diameter side corners and the balls on both side surfaces of the column part, it is preferable that the outer diameter side and inner diameter side corner parts of the both side surfaces of the column part be arcuate surfaces.

  In addition, the present invention provides an outer diameter side and an inner diameter side corner portion of the tip end surface of the column portion on the circular arc surface, so that even if the operator's hand hits each corner portion during the ball capping work, Can prevent injury.

  The cage of the present invention can be obtained by punching a metal plate and then determining and molding the side surface of the column portion.

  In this way, when the side surface of the column portion is determined and pressed, the determined press-molded surface becomes a clean surface with higher accuracy than the punched cross section, so that it is possible to prevent the balls from being damaged.

  According to this invention, the ball can be easily stored in each pocket of the cage, and the efficiency of the assembling work can be improved.

  In addition, by making the corners of the pillars of the cage arcuate, it is possible to prevent injuries to the workers during the capping work.

  Furthermore, according to this invention, the lubrication performance to the ball can be improved and the stability of the ball in each pocket can be improved, so that the frictional resistance between the ball and the cage can be suppressed. Further high speed operation becomes possible.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  As shown in FIGS. 1 and 2, the self-aligning ball bearing with cage according to the present invention allows a plurality of balls 3, 3 to freely roll between an outer ring 1 and an inner ring 2 that are concentrically combined with each other. Are arranged. The cage 4 prevents the balls 3 from coming out even when the inner ring 2, the balls 3 and the cage 4 are freely rotated around the center of the bearing.

  As shown in FIG. 2, an outer ring raceway 5 that is a spherical concave surface having a single center is formed on the inner peripheral surface of the outer ring 1. Further, a pair of inner ring raceways 6 and 6 are formed on the outer peripheral surface of the inner ring 2 so as to face the outer ring raceway 5.

  The self-aligning roller bearing with a cage is used, for example, when the rotating shaft is supported inside the housing, with the outer ring 1 fitted and fixed to the housing and the inner ring 2 fitted and fixed to the rotating shaft. When the inner ring 2 rotates together with the rotation shaft, the balls 3 and 3 roll to allow this rotation. When the shaft center of the housing and the shaft center of the rotating shaft are deviated, the inner ring 2 is aligned inside the outer ring 1 by tilting the central axis of the inner ring 2 with respect to the central axis of the outer ring 1, and this deviation is corrected. To do. In this case, since the outer ring raceway 5 is formed in a single spherical shape, the rolling of the plurality of balls 3 and 3 is smoothly performed even after the deviation correction.

  As shown in FIGS. 2 and 3, the cage 4 of the self-aligning roller bearing according to the present invention includes an annular rim portion 7 disposed between the balls 3, 3 in both rows, and the rim. Columns 8 are arranged on the outer peripheral edges of both side surfaces of the portion 7 at equal intervals in the circumferential direction, and the balls 3 are arranged between the column portions 8 adjacent to each other in the circumferential direction on each side surface of the rim portion 7. Is provided so that the gap between the adjacent pillars 8 and 8 is narrower than the diameter of the ball 3 accommodated in the pocket 9, and the ball 3 extends in the axial direction of the pocket 9. A ball retaining portion 10 for retaining is formed on the side surface of the column portion 8. In FIG. 4 when the cage 4 of FIG. 3 is viewed from the axial direction, the ball retaining portion 10 is indicated by an arrow A. Further, on the inner diameter side of the annular rim portion 7, an auxiliary column portion 11 is provided corresponding to each column portion 8 so that adjacent balls 3 do not interfere with each other.

  As shown in FIG. 4, the interval between the ball retaining portions 10 of the column portions 8 adjacent to each other in the circumferential direction is formed to be narrower than the diameter of the ball 3. Therefore, when assembling the self-aligning roller bearing with a cage, first, as shown in FIG. 5, with the cage 4 fitted on the outer periphery of the inner ring 2, as shown in FIG. The balls 3 are inserted into the gaps 8 from the side, and the balls 3 are accommodated in the pockets 9 of the cage 4. An arrow B in FIG. 4 indicates the direction in which the ball 3 is inserted. When the balls 3 are accommodated in the pockets 9, the balls 3 are separated by the three points of the ball retaining portions 10 of the adjacent pillar portions 8 and 8 and the outer walls of the inner ring raceways 6 and 6 of the inner ring 2, It is possible to prevent the shaft from coming off in the axial direction. FIG. 5 shows a state in which the cage 4 is fitted on the outer periphery of the inner ring 2 and the balls 3 are accommodated in the respective pockets 9 of the cage 4.

  As described above, the balls 3 are stored in the respective pockets 9 of the cage 4 by snapping the balls 3 between the adjacent column portions 8 and 8 as shown in FIG. When the margin between the pillars 8 and 8 is large, a large force is required, and the assembly work takes time and the assembly worker slips his hand excessively when he clicks. There is a risk that the hand may be injured by the pillar portion 8.

  For this reason, in this invention, in order to make it easy to nail the ball 3 from the side between the adjacent column portions 8, the column closer to the rim portion 7 than the ball retaining portion 10 formed on the side surface of the adjacent column portion 8. The portion 8 is provided with a constricted portion 12 that is narrower than the width of the column portion 8 of the ball retaining portion 10. Thus, when the narrowed portion 12 narrower than the width of the column portion 8 of the ball retaining portion 10 is provided in the column portion 8, when the ball 3 is clicked from the side between the adjacent column portions 8, The column portion 8 is bent in the direction in which the constricted portion 12 spreads, and the ball 3 can be easily accommodated between the adjacent column portions 8.

  Next, in the present invention, an inclined guide 13 is provided on the tip side portion from the ball retaining portion 10 of the column portion 8 so that the interval between the pockets 9 between the adjacent column portions 8 is widened.

  As described above, when the inclined guide 13 is provided, the ball 3 hits the inclined guide 13 at the tip end portion of the column portion 8 when the ball 3 is inserted between the adjacent column portions 8 from the side. 13, the adjacent pillars 8 spread each other by the inclined guides 13, and the balls 3 get over the ball retaining parts 10 of the pillars 8, so that the balls 3 easily fit in the pockets 9 between the pillars 8. .

  Since the pillar portion 8 of the cage 4 of the present invention is formed with an inclined guide 13 on the front end side and a narrow constricted portion 12 on the rim portion 7 side with the ball retaining portion 10 in between, the overall shape is an arrowhead shape. I am doing.

  The cage 4 can be manufactured from the punched metal plate 14 having the shape shown in FIG. 7 as follows. On the metal plate 14, arrowhead-shaped column portions 8 and auxiliary column portions 11 are arranged on the outer peripheral edge and the inner peripheral edge of the annular portion forming the rim portion 7 by the number of both sides of the rim portion 7 and meet each other. The cage 4 can be manufactured by bending the column portion 8 and the auxiliary column portion 11 one by one in opposite directions, that is, by bending so that the arrows C and D in FIG.

  As the material of the metal plate 14, an iron-based or copper-based material can be used.

  As described above, when the cage 4 is formed by punching the metal plate 14, each corner portion of the column portion 8 of the cage 4 remains square if the punched cross section is maintained. When the corner portion of the column portion 8 and the ball 3 come into contact with each other, the ball 3 may be damaged, and the lubricating oil may be scraped off at the corner portion to reduce the lubrication performance. Moreover, when each pillar part 8 and the ball 3 hit the corner, the stability of the ball 3 in each pocket 9 is lacking.

  For this reason, in the present invention, after punching out the metal plate 14, each side surface of the column portion 8 is determined and molded into the shapes as shown in FIGS. 6 (a), (b), (c) and (d). In addition, the corner contact between the pillar portion 8 and the ball 3 is eliminated.

  6A, 6B, 6C, and 6D are enlarged views of a portion surrounded by an arrow E in FIG.

  First, FIG. 6A is an example in which both side surfaces of the column part 8 are inclined surfaces in which the interval between the pockets 9 between the column parts 8 adjacent to each other from the inner diameter side toward the outer diameter side is narrowed.

  As shown in FIG. 6A, when the side surface of the column portion 8 is the inclined surface 15, the side surface of the column portion 8 is inclined in the direction along the arc surface of the ball 3. The ball 3 does not hit the corner, the scraping of the lubricating oil is prevented, and the ball 3 can be housed in the pocket 9 in a stable state.

  Next, FIG. 6B is an example in which the side surface of the column portion 8 is formed on the arc surface 16 opposite to the arc direction of the ball 3 accommodated between the pockets 9 between the adjacent column portions 8. .

  As shown in FIG. 6B, by forming the side surface of the column portion 8 on the arc surface 16 opposite to the direction of the arc of the ball 3, the corner portion of the column portion 8 hits the ball 3. In addition, by the arc of the ball 3 and the arc of the column portion 8 in the opposite direction, a lubricating oil sump 17 can be formed on both sides of the contact portion between the ball 3 and the column portion 8 to improve the lubricating effect and Damage can be prevented. Moreover, since the contact area between the ball 3 and the column portion 8 is reduced, the contact resistance is suppressed, and the torque can be reduced.

  Next, FIG. 6C is an example in which both side corners on the outer diameter side of the inclined surface 15 of FIG.

  As shown in FIG. 6 (c), if both corners on the outer diameter side are formed into arcuate surfaces 18, it is possible to prevent injuries due to angular beams even if the worker's hand hits the corner during the ball chamfering operation. .

  Next, FIG. 6D shows an example in which both side surfaces of the column portion 8 are formed on the arc surface 19 in the same direction as the arc of the ball accommodated between the pockets 9 between the adjacent column portions.

  As described above, when the both side surfaces of the column part 8 are formed on the arc surface 19 in the same direction as the arc of the ball accommodated between the pockets between adjacent column parts, the behavior of the ball 3 in the pocket 9 is stable. Turn into. By making the curvature radius of the circular arc surface 19 larger than the curvature radius of the ball 3, contact between the outer diameter side and the inner diameter side corners of the pillar 8 and the ball 3 is avoided. Damage can be prevented. In order to prevent contact between the outer diameter side and inner diameter side corners of the column part 8 and the ball 3, the outer diameter side and inner diameter side corners of the column part 8 both sides are formed into arcuate surfaces 20. preferable.

  Next, corner portions other than the outer diameter side and inner diameter side corner portions on both side surfaces of the column portion 8, that is, the outer diameter side and inner diameter side corner portions of the tip end surface of the column portion 8 are as shown in FIG. The arc surface 21 is preferably formed. As a result, it is possible to further prevent injuries due to corner flashing of each corner portion of the column portion 8.

  In addition, as described above, when the side surface of the pillar portion is determined and molded, the fixed pressing surface is finished to a clean and accurate surface with a punched cross section, so that damage to the ball can be prevented.

  As described above, according to the present invention, the balls 3 can be easily stored in the respective pockets 9 of the cage 4, and the efficiency of the assembling work can be improved.

  Moreover, by making each corner | angular part of the pillar part 8 of the holder | retainer 4 into the circular arc surface 18, 20, 21, it is possible to prevent an operator from being injured during the capping work.

  Furthermore, according to the present invention, the lubrication performance to the balls 3 can be improved, and the stability of the balls 3 in each pocket 9 can be improved. Frictional resistance is suppressed, and higher speed operation is possible.

Partially cutaway perspective view showing an embodiment of a self-aligning ball bearing with a cage of the present invention Partial longitudinal sectional view of the same embodiment Front view of the cage in the above embodiment FIG. 3 is a partially omitted cross-sectional view showing a state where the ball of FIG. 3 is viewed from the axial direction. The perspective view which shows the state which integrated the retainer and the ball | bowl on the outer periphery of the inner ring | wheel in embodiment same as the above. (A)-(d) is a partially abbreviation enlarged view which shows the example of a change of the side shape of the pillar part of the holder | retainer in embodiment same as the above. Exploded view of the cage in the above embodiment The enlarged view which shows the shape of the front end surface of the pillar part of the cage | basket in embodiment same as the above Partially cutaway perspective view showing a conventional self-aligning ball bearing with cage Partial longitudinal sectional view of a conventional example Front view of conventional cage Development view of conventional cage The perspective view which shows the state which integrated the retainer and the ball | bowl on the outer periphery of the inner ring in a prior art example Partially abbreviated cross-sectional view showing a state where a ball is inserted in a conventional example Partially omitted enlarged view showing the contact state between the ball and the pillar in the conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Inner ring 3 Ball 4 Cage 5 Outer ring raceway 6 Inner ring raceway 7 Rim part 8 Column part 9 Pocket 10 Ball retaining part 11 Auxiliary pillar part 12 Constriction part 13 Inclination guide 14 Metal plate 15 Inclination surface 16 Arc surface 17 Lubricating oil Reservoir 18 Arc surface 19 Arc surface 20 Arc surface 21 Arc surface

Claims (10)

  An outer ring raceway which is a spherical concave surface, an outer ring formed on the inner peripheral surface thereof, a pair of inner ring races opposed to the outer ring raceway, an inner ring formed on the outer peripheral surface thereof, and the outer ring raceway between the outer ring raceway and the inner ring raceway. Divided into two rows, a plurality of balls are arranged so as to be able to roll for each row, and a cage having a plurality of pockets for holding these balls so as to roll freely. And an annular rim portion disposed between the balls in both rows, and pillar portions disposed at equal intervals so as to protrude laterally from the outer peripheral edges of both side surfaces of the rim portion. A pocket for holding the ball in a freely rolling manner between the column portions adjacent to each other in the circumferential direction on each side surface of the rim portion, and the interval between the tips of the adjacent column portions is narrower than the diameter of the ball accommodated in the pocket A ball retaining part is formed on the side surface of the pillar part to prevent the ball from slipping to the side of the pocket. In a self-aligning ball bearing with a vessel, a constricted part narrower than the width of the column part in the ball retaining part is provided on the column part closer to the rim part than the ball retaining part formed on the side surface of the adjacent column part. Self-aligning ball bearing with cage, characterized by being provided.   The self-aligning ball bearing with a cage according to claim 1, wherein an inclined guide that increases a pocket interval between adjacent column portions is provided on a tip side portion from a ball retaining portion of the column portion.   The self-aligning ball bearing with a retainer according to claim 1 or 2, wherein both side surfaces of the column part are formed as inclined surfaces in which a pocket interval between adjacent column parts narrows from the inner diameter side toward the outer diameter side. .   The cage according to any one of claims 1 to 3, wherein both side surfaces of the column part are formed on an arc surface opposite to a direction of an arc of a ball accommodated between pockets between adjacent column parts. With self-aligning ball bearing.   The cage according to any one of claims 1 to 3, wherein both side surfaces of the column part are formed on an arc surface in the same direction as an arc direction of a ball accommodated between pockets between adjacent column parts. With self-aligning ball bearing.   The self-aligning ball bearing with retainer according to claim 5, wherein the radius of curvature of the arcuate surfaces on both sides of the column portion is larger than the radius of curvature of the ball accommodated in the pocket.   The self-aligning ball bearing with a retainer according to any one of claims 1 to 6, wherein corners on the outer diameter side and the inner diameter side of the both side surfaces of the column part are formed on a circular arc surface.   The self-aligning ball bearing with a retainer according to any one of claims 1 to 7, wherein a corner portion on an outer diameter side and an inner diameter side of the tip end surface of the column portion is formed in an arc surface.   Claims wherein the annular rim portion and pillar portions disposed at equal intervals in the same direction as the axial direction of the inner ring are formed on the outer peripheral edges of both side surfaces of the rim portion by punching a metal plate. Item 9. A self-aligning ball bearing with a cage according to any one of items 1 to 8.   The self-aligning ball bearing with a retainer according to claim 9, wherein a punching surface of a side surface of the column portion is press-molded.

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