JP2008168835A - Caster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a caster manufacturable at low cost since the number of parts is less and having a wheel frame smoothly rotatable since a ball bearing is not rattled even if it is used for a long period. <P>SOLUTION: In this caster 100, a bearing case upper half body 30 formed integrally with the upper surface part 11 of the wheel frame 10 is joined to a bearing case lower half body 40 through flange parts 32, 42. A ball bearing 20 is contained in the containing spaces 31, 41 formed by the bearing case upper half body 30 and the bearing case lower half body 40. The bearing case upper half body 30 and the bearing case lower half body 40 are fitted and fixed to the outer peripheral surface and the upper and lower end surfaces of the outer ring 21 of the ball bearing 20. The upper and lower end surfaces of the inner ring 22 of the ball bearing 20 are held by the upper and lower flange parts 82, 83 of the cylindrical part 81 of an adapter 80. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a caster attached to a shopping cart, a pedestal of a movable bed, and other various moving bodies.

  The caster is used by being attached to a base such as a shopping cart or a movable bed as a part that can move while freely changing the traveling direction. As this type of caster, the wheel frame and the bearing case are separated, and the small-diameter cylindrical portion of the bearing case made of a different-diameter cylindrical body is inserted into the hole in the upper plate of the wheel frame and bent. A type that adheres to is known. With this type, the bent part will loosen due to long-term use, etc., causing looseness in the fixed state, making it difficult for the top plate of the wheel frame to rotate, and the wheel supported on the side plate of the wheel frame to rotate smoothly. Disappear. In this type, since the wheel frame and the bearing case are separated, the number of parts is large, the number of processing and assembly steps is increased, and the cost is increased.

Thus, Patent Document 1 discloses a caster in which a wheel frame and a bearing case are integrally formed. In this caster, a cylindrical portion that functions as a bearing case is formed by making a hole in the upper plate of the wheel frame and then extruding the upper plate downward, so that the wheel frame and the bearing case are integrated. ing. A ball bearing is housed in this bearing case, the outer periphery of the ball bearing is fixed to the bearing case by drawing around the upper end of the bearing case, and a pedestal is stacked with a space ring on the upper end surface of the inner ring of the ball bearing. Insert the washer from above the pedestal with the washer between the lower end face of the inner ring and pass the inner ring of the ball bearing to the inner ring of the ball bearing. Yes.
JP 2002-120505 A

  However, in the caster disclosed in Patent Document 1, since the outer ring of the ball bearing is fixed around the upper end of the bearing case formed by drawing, the outer ring of the ball bearing is only partially fixed to the bearing case. In addition, since the bearing case is formed by extruding the upper plate of the wheel frame, the thickness of the portion that becomes the bearing case is reduced. Therefore, there is a problem that the holding of the outer ring of the ball bearing by the bearing case is insufficient, and the adhesion of the outer ring of the ball bearing to the bearing case may be released by a load applied to the caster. If the ball bearing is not stably held, the wheel frame is not stably and smoothly rotated around the stop shaft, so the wheel frame is difficult to rotate around the stop shaft. The wheel pivotally supported on the side plate portion of the wheel frame is difficult to smoothly travel and rotate.

  In particular, when a caster is attached to a leg portion of a shopping card and used, a plurality of casters are nested and arranged at a predetermined location. Since the pushing load is applied by about 1 ton, there is a possibility that the bearing case constituted by a part of the upper plate is damaged. Further, the side plate portion that hangs down from both sides from the upper plate of the wheel frame is formed so as to extend in a vertical direction from a hole for supporting the wheel, and a part thereof is connected to the upper plate side. Therefore, since it is difficult to suppress the thrust load when the caster hits the step, there is a high probability that the outer bearing of the ball bearing is fixed to the bearing case by the thrust load.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention has an object to provide a caster that retains a ball bearing even when used for many years, smoothly rotates the wheel frame, and smoothly rotates the wheel pivotally supported by the wheel frame. And

  In order to achieve the above object, a caster according to the present invention includes a ball bearing, a wheel frame having a pair of side surfaces hanging from both sides of the upper surface portion and the upper surface portion, and arranged to straddle the wheels. An upper half of a bearing case that forms a housing space for housing a part of the ball bearing in close contact with a part of the outer peripheral surface of the outer ring and the upper end surface of the ball bearing on the upper surface of the wheel frame; And a bearing case lower half defining a housing space for housing the other part of the ball bearing in close contact with the other part and the lower end surface of the outer ring.

  Specifically, it has a ball bearing and a pair of side surfaces depending from both sides of the upper surface portion and the upper surface portion, and the wheel frame arranged to straddle the wheels, and the upper surface portion of the wheel frame, The ball bearing has a housing space that is in close contact with the upper half and the upper end surface of the outer ring of the outer ring and accommodates the upper half of the ball bearing, and has a flange portion that forms a joint surface in the center of the width of the outer ring of the ball bearing. The bearing case upper half and the lower half of the outer peripheral surface of the outer ring and the lower end face of the ball bearing are in close contact with the accommodation space for accommodating the lower half of the ball bearing, and are joined to the center of the outer ring width of the ball bearing. A bearing case lower half having a flange portion formed with a surface, and tightly fixing the joint surface of the flange portion in the upper half of the bearing case and the joint surface of the flange portion in the lower half of the bearing case Composed.

  According to the above configuration, the ball bearing is composed of the bearing case upper half formed integrally with the upper surface portion of the wheel frame, and the bearing case lower half joined to the bearing case upper half from below. A space to be accommodated is formed, the ball bearing is accommodated in this space, and the upper and lower end surfaces of the outer ring in the ball bearing are held. Therefore, the upper half of the bearing case and the lower half of the bearing case maintain the thickness and can be used for many years, so that the upper half of the bearing case and the lower half of the bearing case firmly fix the outer ring of the ball bearing. Can do.

  In the above configuration, preferably, a decorative annular plate mounted on the bearing case upper half, and a through hole provided coaxially in the decorative annular plate, the bearing case upper half and the bearing case lower half An adapter that is inserted, and is held in close contact with the upper and lower end surfaces of the inner ring of the ball bearing at the upper and lower flanges of the cylindrical portion of the adapter. Preferably, the upper surface portion of the wheel frame is formed in a circular shape, the pair of side surface portions of the wheel frame are formed in a circular arc shape along the upper surface portion, and are flat so as to sandwich the wheel in the vicinity of supporting the wheel. It is formed in a shape.

  According to the above configuration, the upper and lower end surfaces of the inner ring of the ball bearing are held by the upper and lower flanges of the cylindrical portion of the adapter. Thereby, even if a caster is fixed to a predetermined wearing device such as a shopping cart, the wheel frame rotates smoothly and stably around the through hole. Since the side surface portion of the wheel frame is formed along the outer periphery of the upper surface portion and is formed in a flat plate shape only in the vicinity of the wheel shaft hole, when the caster hits the step and a thrust load is applied to the caster, the force In addition to being able to escape, the bending resistance of the side surface portion can be ensured.

  According to the present invention, even when used for many years, the outer ring in the ball bearing is held by the bearing case upper half and the bearing case lower half, and the inner ring in the ball bearing is held by the upper and lower flanges of the adapter. In the space defined by the upper half of the bearing case and the lower half of the bearing case, the ball bearing is fixed and held without rattling, and the wheel frame rotates smoothly. Therefore, the wheel pivotally supported by the wheel frame can turn smoothly.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are used for the same or corresponding members.
FIG. 1 is a longitudinal side view of a caster according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. In the caster 100 according to the embodiment of the present invention, the bearing case upper half 30 and the bearing case lower half 40 formed integrally with the upper surface portion 11 of the wheel frame 10 are joined surfaces of the flange portions 32 and 42. The ball bearing 20 is accommodated in a space defined by the bearing case upper half 30 and the bearing case lower half 40, and the bearing case upper half 30 and the bearing case lower half 40 are ball bearings. 20 is configured to be in close contact with the outer peripheral surface and upper and lower end surfaces of the outer ring 21.

  As shown in FIGS. 1 and 2, the caster 100 according to this embodiment is a wheel that fixes and supports a wheel 90 and both ends of an axle 94 that is disposed so as to straddle the wheel 90 and inserted through the wheel 90. The bearing frame 10, the bearing case lower half 40 joined to the bearing case upper half 30 defined on the upper surface portion 11 of the wheel frame 10, and the bearing case upper half 30 are mounted. A decorative annular plate 60, and an adapter 80 inserted through a through hole provided coaxially in the decorative annular plate 60, the bearing case upper half 30 and the bearing case lower half 40.

  The wheel frame 10 has an upper surface portion 11 and a pair of side surface portions 12, 12 that hang down from the left and right sides of the upper surface portion 11, and a shaft hole 13 through which the axle 94 is inserted under the side surface portion 12 (see FIG. 3). Have The upper surface portion 11 of the wheel frame 10 is formed in a circular shape, that is, a circular lid shape, and the pair of side surface portions 12 and 12 of the wheel frame 10 are formed in an arc shape along the upper surface portion 11. It is formed in a flat plate shape so as to sandwich the wheel 90 near the shaft. The wheel frame 10 is made of a metal such as stainless steel or steel and plated as necessary, and can be manufactured through press molding or the like.

  The bearing case upper half 30 is formed in a two-stage circular pedestal shape. This can be formed by, for example, extruding upward after providing a through hole in the upper surface portion 11 of the wheel frame 10. The bearing case upper half 30 is a space that accommodates a part of the outer peripheral surface of the outer ring 21 in the ball bearing 20, preferably the upper half and the upper end surface, and accommodates a part of the ball bearing 20, preferably the upper half. A space 31 is defined (see FIG. 3). A flange portion 32 is formed in the bearing case upper half 30 so as to have a joint surface at the center of the width of the outer ring 21 in the ball bearing 20.

  The lower half 40 of the bearing case is in close contact with the other part of the outer peripheral surface of the outer ring 21 in the ball bearing 20, preferably the lower half and the lower end face, and accommodates the other part of the ball bearing 20, preferably the lower half. A space, that is, an accommodation space 41 is defined. The bearing case lower half 40 has a donut-shaped flange portion 42 so as to have a joint surface at the center of the width of the outer ring 21 in the ball bearing 20. Reinforcing cylindrical ribs 43 are formed on the peripheral edge of the flange portion 42. Here, the lower half 40 of the bearing case is made of a metal such as stainless steel or steel, and is plated as necessary. For example, the bearing case lower half 40 can be manufactured through press molding or the like.

  The ball bearing 20 is preferably a deep groove ball bearing in which the rolling ball rolls stably, a so-called deep groove radial ball bearing. Here, the outer ring 21 and the inner ring 22 that sandwich the rolling ball may be chamfered with circular arcs, but it is preferable that the outer ring 21 and the inner ring 22 be chamfered as little as possible. It has a curved surface with a curvature of 0.5 mm. This is because the outer ring 21 and the inner ring 22 of the ball bearing 20 can be held firmly when the contact surface between the bearing case upper half 30 and the bearing case lower half 40 is larger.

  The decorative annular plate 60 has a circular arc cross section in the form shown in the figure, and is mounted on the bearing case upper half 30 to conceal the ball bearing 20 and improve the aesthetic appearance. It plays the role of preventing the ingress of water and dust. The decorative annular plate 60 is formed by press-molding a metal plate such as a stainless steel plate, or is formed by using a hard resin such as Duracon (registered trademark: polyacetal material of Polyplastics). In addition, the center part of the decorative annular plate 60 may be flat as shown in the figure, or a recess may be provided only at the periphery of the through hole.

  The washer 70 is mounted on the upper surface portion 31 of the bearing case upper half 30 so as to overlap the upper end surface of the inner ring 22 in the ball bearing 20.

  The adapter 80 has a tubular portion 81 and a flange portion 82 at the upper end portion of the tubular portion 81, and the tubular portion 81 is passed through the inner ring 22 of the ball bearing 20 by being fitted and crossed. The flange is formed by flange processing to form a flange 83, which is in close contact with the lower end surface of the inner ring 22 and fixed to the inner ring 22 of the ball bearing 20 (see FIGS. 4 and 5). The adapter 80 is, for example, a stainless steel molded product or is formed by chromium plating on a steel plate molded product.

  The wheel 90 includes a wheel body 91 having a hard and tough synthetic resin frame portion 91a and a tough synthetic resin shell member 91b having a slight flexibility on its outer periphery, and an axle 94 on the wheel body 91. And another ball bearing 92 that is rotatably supported. The frame portion 91a is formed with a bearing portion 91c in the axle direction. The bearing portion 91c has an annular groove at the center of the width of the axle 94, and the outer ring of the ball bearing 92 is forcibly fitted and held in the annular groove. On the other hand, a pair of decorative bearings 93, 93 are fitted on both sides of the wheel body 91, and the decorative bearing 93 has a decorative disc portion 93b and a bush portion having a bolt through hole / shaft hole 93c at the center of the decorative disc portion 93b. 93a. The decorative disc portion 93b covers the recessed space corresponding to the rim portion of the frame portion 91a of the wheel body 91.

Next, the caster 100 according to the present invention will be described in more detail by explaining an assembly method of the caster 100. 3 to 5 are cross-sectional views showing an assembly process of the caster 100 shown in FIGS.
As a first step, the flange portion 32 of the bearing case upper half 30 and the flange portion 42 of the bearing case lower half 40 formed integrally with the upper surface portion 11 of the wheel frame 10 are joined. As shown in FIG. 3, the bearing case upper half 30 formed integrally with the upper surface portion 11 of the wheel frame 10 is provided with a through hole in the upper surface portion 11, and is formed in a two-stage circle by an upward extrusion process. It has a pedestal shape, and the outer peripheral edge of the through hole extends vertically upward. The flange portion 32 of the bearing case upper half 30 formed on the upper surface portion 11 and the flange portion 42 of the bearing case lower half 40 are joined. Joining is performed at a predetermined interval so as to surround the through-holes at a plurality of points, for example, four points (points indicated by w), and at a substantially intermediate position between the point-welded points, the side surface portion of the wheel frame 10 is joined. 12 and the outer peripheral edge of the bearing case lower half 40 are welded. At this time, in the bearing case lower half 40, the flange portion 42 is in close contact with the flange portion 32 of the bearing case upper half 30 and the cylindrical rib 43 is connected to the first cylindrical portion 33 of the bearing case upper half 30. , And is positioned concentrically to avoid applying a shearing force to the spot weld w as much as possible. Further, the bearing case lower half 40 is bonded by spot welding the flanges 32, 42 with the flange 42 closely attached to the flange 32 of the bearing case upper half 30. The spot welding locations denoted by reference symbol w are the center of the width in the diameter direction of the flange portions 32 and 42 and are, for example, four locations in the circumferential direction.

  As a second step, as shown in FIG. 3, storage spaces 31 and 41 defined by a bearing case upper half 30 and a bearing case lower half 40 integrally formed on the upper surface portion 11 of the wheel frame 10. Next, the ball bearing 20 is accommodated. Drawing is performed such that the outer peripheral edge of the through hole of the bearing case upper half 30 is bent into an L-shaped cross section, and the outer peripheral edge 21 of the ball bearing 20 accommodated is closely contacted.

  As a third step, as shown in FIG. 4, a washer 70 is placed on the upper end surface of the inner ring 22 in the ball bearing 20, and a decorative annular plate 60 is stacked on the washer 70, and the washer 70, the inner ring 22 of the ball bearing 20, and An adapter 80 is inserted from above into a through hole formed concentrically in the lower half 40 of the bearing case. At this time, the washer 70 serves as a spacer so that the bearing case upper half 30 and the decorative annular plate 60 do not come into contact with each other.

As a fourth step, as shown in FIG. 5, a flange 83 is formed by pressing at the lower end of the cylindrical portion 81 of the adapter 80 and is held in the vertical direction by the upper and lower flanges 82 and 83 of the adapter 80.
As a fifth step, as shown in FIGS. 1 and 2, wheels 90 are arranged between the side portions 12, 12 on both sides of the wheel frame 10, and an axle 94 made of a bolt is connected to the shaft hole 13 of one side portion 12. The bolt hole and shaft hole 93c and the shaft hole 13 of the other side surface portion 12 are sequentially inserted, a nut 95 is fastened to the screw portion at the tip of the axle 94, and the side plate portions 12 and 12 on both sides include a bush portion 93a. The bearings 93 and 93 and the axle 94 are fixed.
From the above, the caster 100 shown in FIGS. 1 and 2 can be assembled.

  The caster 100 assembled in this way is attached to a mounting portion P provided at the bottom of various transport vehicles and transport equipment such as a shopping cart and a movable bed. That is, as shown in FIGS. 1 and 2, the mounting bolt 50 fitted with the flat washer 51 is passed through the cylindrical portion 81 of the adapter 80 from below, and the mounting bolt 50 is passed through the bolt through hole of the mounting portion P. The spring washer 52 is fitted and the double nuts 53 and 54 are tightened and attached. The mounting bolt 80 used here may be made of non-rust steel such as stainless steel or may be chromium plated on a steel rolled product.

  As described above, in the caster 100 according to this embodiment, the housing space 31 of the bearing case upper half 30 is formed as a cylindrical space with the ball bearing 20 opened at the top, and the flange of the bearing case upper half 30 is formed. The ball bearing 20 is accommodated after the portion 32 and the bearing case lower half 40 flange portion 42 are spot welded at the joint surface, and thereafter, the cylinder forming the cylindrical space of the bearing case lower half 40 The upper end portion 34 of the shaped portion is drawn, and the upper end surface of the outer ring 21 in the ball bearing 20 is crimped. On the other hand, the upper and lower flange portions 82 and 83 of the cylindrical portion 81 of the adapter 80 are held in close contact with the upper and lower end surfaces of the inner ring 22 of the ball bearing 20. Therefore, in the caster 100 according to this embodiment, the inner ring 22 and the outer ring 21 of the ball bearing 20 are respectively pressed and held from above and below, so that the wheel frame 10 can be stably turned around the axial direction of the adapter 80. The wheel 90 can be rotated. Therefore, according to this caster, the number of parts is small and the cost is not increased, the ball bearing 20 does not rattle even when used for many years, and the wheel frame 10 does not become difficult to rotate. The wheel 90 that is pivotally supported by the side surface portion 12 smoothly turns.

  Since the cylindrical portion 81 of the adapter 80 is used as a cylindrical inner surface as a surface to be fitted with the mounting bolt 50, a long cylindrical inner surface is secured, so that the mounting bolt 50 and the inner ring 22 of the ball bearing 20 are interposed via the adapter 80. A large fixing strength can be secured. Further, the side surface portion 12 of the wheel frame 10 is formed in a flat plate shape only in the vicinity of the shaft hole 13, and the curved surface curved along the circular upper surface portion 11 of the wheel frame 10 is enlarged in other portions. Thus, for example, in the caster 100 used in a shopping cart, the stress of the pushing force generated in the caster 100 when the caster 100 hits the step when the cart is cleared is reduced, and the side part 12 has a large bending resistance. It will not be bent from the fact.

  Furthermore, since the caster is attached by tightening the nuts 53 and 54 of the mounting bolt 50 to the mounted portion P provided at the bottom of the transportation equipment or various transport vehicles, the mounting bolt 50 has been loosened for many years of use. In this case, the caster can be firmly fixed to the mounted portion P again by tightening the lock nut.

The present invention is not limited to the above-described matters, and various modifications are possible within the scope described in the claims. For example, the following modifications are also included in the present invention.
The 1st and 2nd modification shows an example of the modification of the assembly process of caster 100.
FIG. 6 is a cross-sectional view showing a process of assembling the caster 100 according to the first modification. As shown in FIG. 6, the bearing case upper half 30 is turned upside down, a part of the ball bearing 20 is accommodated in the accommodation space 31, and then an end edge portion 44 that presses the end face of the outer ring 21 of the ball bearing 20 is provided in advance. The bearing case lower half 40 processed into a bent state is turned upside down and forcibly fitted to the other part of the ball bearing 20 so as to be accommodated in the accommodating space 41. In this case, the flange portion 32 and the flange portion 42 are further moved from a state in which the flange portion 32 of the bearing case upper half 30 and the flange portion 42 of the bearing case lower half 40 are close to each other so that a gap of, for example, 0.3 mm is opened. May be incorporated into the state shown in FIG. 1 by performing spot welding with the flange portions 32 and 42 in close contact with each other.

  FIG. 7 is a cross-sectional view showing a process of assembling the caster 100 according to the second modification. As shown in FIG. 7, the bearing case upper half 30 is inverted and a part of the ball bearing 20 is accommodated in the accommodating space 31. Next, the bearing case lower space 40 in a state where the end edge portion 44 that presses the end surface of the outer ring 21 of the ball bearing 20 is not bent in advance is inverted, and the bearing housing space 41 is forcibly fitted to the other portion of the ball bearing 20. At the same time, the flange portion 32 of the bearing case upper half 30 and the flange portion 42 of the bearing case lower half 40 are overlapped to perform spot welding w. Next, the end 44 of the cylindrical portion forming the cylindrical space of the lower half 40 of the bearing case is drawn and the end surface of the outer ring 21 of the ball bearing 20 is crimped, whereby the ball bearing 20 is shown in FIG. It may be incorporated in the state shown in FIG. At this time, the end portion 83 of the cylindrical portion 81 of the adapter 80 is flanged either before or after the front end portion 44 is drawn.

  In the third modified example, as in the embodiments shown in FIGS. 1 to 5 and modified examples 1 and 2, each part is formed of a metal such as stainless steel and the assembly process is not performed. The caster may be configured by molding with resin so as to hold the body 30 and the lower half 40. As the resin, it is preferable to use a hard resin such as Duracon (registered trademark: polyacetal material of Polyplastics).

It is a vertical side view of the caster which concerns on embodiment of this invention. It is II-II sectional drawing in FIG. It is sectional drawing which shows 1 process in the assembly process of the caster shown in FIG.1 and FIG.2. FIG. 4 is a cross-sectional view illustrating a process following FIG. 3 in the assembly process of the caster illustrated in FIGS. 1 and 2. FIG. 5 is a cross-sectional view illustrating a process following FIG. 4 in the assembly process of the casters illustrated in FIGS. 1 and 2. It is sectional drawing which shows 1 process of the assembly of the caster which concerns on a 1st modification. It is sectional drawing which shows 1 process of the assembly of the caster which concerns on a 2nd modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100: Caster 10: Wheel frame 11: Upper surface part 12: Side surface part 13: Shaft hole 20, 92: Ball bearing 21: Outer ring 22: Inner ring 30: Bearing case upper half 31, 41: Housing space 32, 42: Flange Part 33: Cylindrical part 34: Upper end part 40: Bearing case lower half 43: Cylindrical rib 44: End edge part 50: Mounting bolt 51: Plain washer 52: Spring washer 53, 54: Nut 60: Decorative annular plate 70: Washer 80: Adapter 81: Tube portion 82, 83: Ridge portion 90: Wheel 91: Wheel body 91a: Frame portion 91b: Shell member 91c: Bearing portion 93: Cosmetic bearing 93a: Bush portion 93b: Cosmetic disc portion 93c: Bolt Through-hole shaft hole

Claims (4)

Ball bearings,
A wheel frame having a top surface and a pair of side surfaces depending from both sides of the top surface, and arranged to straddle the wheel;
A bearing case upper half that forms an accommodation space for accommodating a part of the ball bearing in close contact with a part of the outer peripheral surface of the outer ring and the upper end surface of the ball bearing on the upper surface of the wheel frame;
A lower half of the bearing case defining an accommodation space for accommodating the other part of the ball bearing in close contact with the other part and the lower end surface of the outer ring of the outer ring in the ball bearing;
A caster, comprising: Ball bearings,
A wheel frame having a top surface and a pair of side surfaces depending from both sides of the top surface, and arranged to straddle the wheel;
The upper surface of the wheel frame has a housing space that is in close contact with the upper half and the upper end surface of the outer ring of the ball bearing and accommodates the upper half of the ball bearing, and the outer ring of the ball bearing A bearing case upper half having a flange portion formed with a joint surface in the width center;
The ball bearing has a housing space that is in close contact with the lower half and the lower end surface of the outer ring of the outer ring and accommodates the lower half of the ball bearing, and a joint surface is formed at the center of the width of the outer ring of the ball bearing. A bearing case lower half having a flange portion,
A caster, characterized in that the joint surface of the flange portion in the upper half of the bearing case and the joint surface of the flange portion in the lower half of the bearing case are closely fixed. A decorative annular plate mounted on the upper half of the bearing case, and a through hole provided coaxially in the decorative annular plate, the upper half of the bearing case, and the lower half of the bearing case An adapter, and
3. The caster according to claim 1, wherein the casters are held in close contact with upper and lower end surfaces of the inner ring of the ball bearing at upper and lower flange portions of the cylindrical portion of the adapter. The upper surface of the wheel frame is formed in a circular shape,
The pair of side surface portions of the wheel frame has an arcuate cross section along the upper surface portion, and is formed in a flat plate shape so as to sandwich the wheel in the vicinity of supporting the wheel. Or the caster of 2.

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