Double-wheel hollow caster

Abstract

A double-wheel hollow caster 1 according to the present invention comprises a body 13 having a hollow section 13A, a substantially cylindrical pipe member 11P disposed so as to pass through the hollow section 13A, a pair of wheels 15, 15 attached to the two ends of the pipe member 11P, and a single bearing 11B sandwiched between the body 13 and the pipe member 11. Therefore, the single bearing 15 can be shared by the pair of wheels 15, 15, and the sliding properties of the pair of wheels 15, 15 can easily be enhanced by using a ball bearing as the single bearing 15.

Description

Double-wheel hollow caster

[0001] The present invention relates to a caster that can be attached to the bottom of heavy objects such as push-carts, hand trucks, wagons, furniture such as tables, chairs, dressers, and shelves, vehicles such as wheelchairs and strollers, and other heavy objects used in facilities such as shopping malls, supermarkets, and airports, and in particular to a hollow, dual-wheeled caster with two wheels.

[0002] For example, Figures 1 to 3 of Patent Document 1 disclose a dual-wheel hollow caster. This dual-wheel hollow caster has a ring-shaped holder 3 attached to a ring-shaped main body 1, and a pair of wheels 2, 2 attached to both sides of the holder 3, with dry bearings 5 ​​sandwiched between the holder 3 and the pair of wheels 2, 2, and between the main body 1 and the pair of wheels 2, 2. This type of dual-wheel hollow caster has the advantage that the pair of wheels 2, 2 are less likely to open in a V-shape when a load is applied, reducing the likelihood of damage to parts compared to non-hollow dual-wheel casters.

[0003] JP 2011-251653 A

[0004] However, the dual-wheel hollow caster shown in Figures 1 to 3 of Patent Document 1 is equipped with a total of four dry bearings, two on each side, and either requires grease to improve the smoothness (sliding properties) of each of these dry bearings, or omits grease and has to accept poor smoothness (sliding properties).

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a dual-wheel hollow caster that is easy to improve sliding properties and has a simple structure.

[0006] In order to solve the above problems, one double-wheel hollow caster of the present invention is characterized by comprising a main body having a hollow portion, an approximately cylindrical pipe member arranged to pass through the hollow portion, a pair of wheels attached to both ends of the pipe member, and a single bearing sandwiched between the main body and the pipe member.

[0007] In order to solve the above problem, in a dual-wheel hollow caster according to the present invention, one of the pair of wheels may each have an inner ring attached to one end of the pipe member and an outer ring attached around the inner ring.

[0008] In order to solve the above problem, in a dual-wheel hollow caster according to the present invention, the bearing may be a shielded ball bearing.

[0009] In order to solve the above problem, in a dual-wheel hollow caster according to the present invention, the ball bearing may be made of stainless steel.

[0010] The dual-wheel hollow caster of the present invention comprises a main body having a hollow portion, a substantially cylindrical pipe member disposed so as to pass through the hollow portion, a pair of wheels attached to both ends of the pipe member, and a single bearing sandwiched between the main body and the pipe member, thereby allowing a single bearing to be shared by the pair of wheels, and by using a ball bearing as the single bearing, it is easy to improve the sliding properties of the pair of wheels. Therefore, the present invention has the advantage of realizing a dual-wheel hollow caster with a simple configuration that makes it easy to improve sliding properties. Furthermore, because the dual-wheel hollow caster of the present invention shares a single bearing with the pair of wheels, it also has the advantage of requiring fewer parts and being easier to assemble.

[0011] Figure 1(A) is a perspective view of a dual-wheel hollow caster according to this embodiment, and Figure 1(B) is a perspective view of the dual-wheel hollow caster seen from a different direction than Figure 1(A). Figure 2 is an exploded view of the dual-wheel hollow caster. Figure 3(A) is an assembly diagram of the wheels, and Figure 3(B) is an assembly diagram of the bearings and their surroundings. Figure 4(A) is a side view of the dual-wheel hollow caster, and Figure 4(B) is a cross-sectional view taken along line A-A in Figure 4(A).

[0012] A preferred embodiment of a dual-wheel hollow caster according to the present invention will be described below with reference to the drawings. The dual-wheel hollow caster according to this embodiment is, for example, a caster for a chair. However, this dual-wheel hollow caster can also be used as a caster for moving heavy objects other than chairs.

[0013] FIG. 1(A) is a perspective view of a dual-wheel hollow caster according to this embodiment, FIG. 1(B) is a perspective view of the dual-wheel hollow caster seen from a different direction than FIG. 1(A), FIG. 2 is an exploded view of the dual-wheel hollow caster, FIG. 3(A) is an assembly diagram of the wheels, FIG. 3(B) is an assembly diagram of the surrounding area of ​​the bearing, FIG. 4(A) is a side view of the dual-wheel hollow caster, and FIG. 4(B) is a cross-sectional view taken along line A-A in FIG. 4(A).

[0014] As shown in Figures 1 and 2, the double-wheel hollow caster 1 of this embodiment includes a main body 13 having a hollow portion 13A, a substantially cylindrical pipe member 11P arranged to pass through the hollow portion 13A, a pair of wheels 15, 15 attached to both ends (around) of the pipe member 11P, a bearing portion 13B made of the same material as the main body 13 and located outside the hollow portion 13A of the main body 13, a shaft 11 that fits into the bearing portion 13B, and a cover 12 that covers the fitting portion between the main body 13 and the shaft 11.

[0015] 2 and 3(A), one of the pair of wheels 15, 15 of this dual-wheel hollow caster 1 includes an inner ring 15in attached to the periphery of one open end of the pipe member 11P, and an outer ring 15out attached to the periphery of the inner ring 15in. When the inner ring 15in is attached to the periphery of the pipe member 11P, a fitted portion 15in-1 (FIG. 2) on the inside of the inner ring 15in fits into a fitting portion 11P-1 (FIG. 2) on the periphery of the pipe member 11P.

[0016] 2 and 3(A), the other of the pair of wheels 15, 15 of the dual-wheel hollow caster 1 includes an inner ring 15in attached to the periphery of the other open end of the pipe member 11P, and an outer ring 15out attached to the periphery of the inner ring 15in. When the inner ring 15in is attached to the periphery of the pipe member 11P, a fitted portion 15in-1 (FIG. 2) on the inside of the inner ring 15in fits into a fitting portion 11P-1 (FIG. 2) on the periphery of the pipe member 11P.

[0017] The shape of the peripheral wall (ring portion) of the hollow portion 13A of the main body 13 is asymmetrical in the vertical direction, with the radial thickness being greater at the top side than at the floor side. When the wheels 15, 15 are attached, the upper end of the peripheral wall (ring portion) of the main body 13 and the upper end of the wheels 15, 15 are at approximately the same height, but the lower end of the peripheral wall (ring portion) of the main body 13 is located higher than the lower ends of the wheels 15, 15. Therefore, when the wheels 15, 15 are placed on the floor, the lower end of the peripheral wall (ring portion) of the main body 13 is floating above the floor.

[0018] As shown in FIG. 3B , a single bearing 11B is sandwiched between the main body 13 and the pipe member 11P, and this bearing 11B is shared by a pair of wheels 15, 15. The inner periphery of the inner ring of the bearing 11B is fixed to the pipe member 11P, and the outer periphery of the outer ring of the bearing 11B is fixed to the main body 13. Here, the method of fixing the inner ring of the bearing 11B to the pipe member 11P and the method of fixing the outer ring of the bearing 11B to the main body 13 are, for example, as follows. That is, first, the bearing 11B is inserted into a mold for molding the pipe member 11P and injection molded, thereby integrating the inner periphery of the inner ring of the bearing 11B with the pipe member 11P. Next, the integrated bearing 11B and pipe member 11P are inserted into a mold for molding the main body 13 and injection molded, thereby integrating the outer periphery of the outer ring of the bearing 11B with the main body 13. With this fixing method, the components are integrated during the molding process, which makes it possible to reduce the number of components, make the components smaller, and improve the strength of the components compared to assembling the components in a process after the molding process. Also, the bearing 11B of this embodiment is a stainless steel shielded ball bearing, which is more expensive than a dry bearing but has the advantage of high sliding properties and not requiring grease.

[0019] The shaft 11 is made of a metal such as iron, the cover 12 is made of a synthetic resin such as PA6 (6 nylon resin), the main body 13 is made of a synthetic resin that is both wear-resistant and strong such as PA6GF30 (polyamide 6 glass fiber 30%), the pipe member 11P is made of a synthetic resin that is both lubricated and strong such as POM-GF30% (polyacetal POM material polyoxymethylene), the inner ring 15in is made of a synthetic resin such as PA6 (6 nylon resin), and the outer ring 15out is made of a synthetic resin with adequate grip such as TPU (thermoplastic polyurethane elastomer). However, these materials are not limited to these, and appropriate materials can be used depending on the function of each component.

[0020] As described above, the dual-wheel hollow caster 1 according to this embodiment shares a single bearing 11B for the pair of wheels 15, 15, and because this bearing 11B is a ball bearing, it is easy to improve the sliding properties of the pair of wheels 15, 15 and has a simple configuration. Furthermore, the dual-wheel hollow caster 1 according to this embodiment shares a single bearing 11B for the pair of wheels 15, 15 and does not use screws or the like, so the number of parts is small and assembly is easy.

[0021] The present invention is not limited to the above-described embodiments, and various modifications of the components can be made without departing from the spirit of the present invention. Furthermore, various inventions can be realized by appropriately combining the components disclosed in each embodiment. For example, the diameter and / or width of the pair of wheels 15, 15, the ratio of the diameter and width, and the combination pattern of the components can be changed depending on the intended use of the caster.

[0022] For example, it is possible to realize a dual-wheel hollow caster consisting of only the five components (shaft 11, cover 12, body 13, wheels 15, 15) illustrated in Fig. 2, or it is also possible to realize a dual-wheel hollow caster by adding one or more components not shown to the five components (shaft 11, cover 12, body 13, wheels 15, 15) illustrated in Fig. 2. It is also possible to realize a dual-wheel hollow caster by omitting either or both of the shaft 11 and the cover 12 from the five components (shaft 11, cover 12, body 13, wheels 15, 15) illustrated in Fig. 2.

[0023] It is also possible to realize any of the following aspects 1 to 5. (Aspect 1): A dual-wheel hollow caster comprising: a main body having a hollow portion; a substantially cylindrical pipe member disposed so as to pass through the hollow portion; a single bearing sandwiched between the main body and the pipe member, the single bearing having an outer ring integrally molded with the main body and an inner ring integrally molded with the pipe member; and a pair of wheels attached to both open ends of the pipe member that protrude outward from the main body, with no other bearings provided. (Aspect 2): A dual-wheel hollow caster in Aspect 1, wherein one and the other of the pair of wheels each have an inner ring attached to one end of the pipe member and an outer ring attached around the inner ring. (Aspect 3): A dual-wheel hollow caster in Aspect 1 or Aspect 2, wherein the bearing is a shielded ball bearing. (Aspect 4): A dual-wheel hollow caster in any of Aspects 1, 2, and 3, wherein the ball bearing is made of stainless steel. (Aspect 5): A method for manufacturing a double-wheel hollow caster according to any one of Aspects 1, 2, 3, and 4, comprising the steps of: inserting the bearing into a mold for molding the pipe member and injection molding it to integrate the inner ring of the bearing with the pipe member; and inserting the integrated bearing and pipe member into a mold for molding the main body and injection molding it to integrate the outer ring of the bearing with the main body.

[0024] 1 Dual-wheel hollow caster 11 Shaft 12 Cover 13 Body 13A Hollow portion 13B Bearing portion 11P Pipe member 11P-1 Fitting portion 11B Bearing 15 Wheel 15out Outer ring 15in Inner ring 15in-1 Fitted portion

Claims

1. A dual-wheel hollow caster comprising: a main body having a hollow portion; a substantially cylindrical pipe member arranged to pass through said hollow portion; a pair of wheels attached to both ends of said pipe member; and a single bearing sandwiched between said main body and said pipe member.

2. A dual-wheel hollow caster as described in claim 1, wherein one of the pair of wheels and the other wheel each have an inner ring attached to one end of the pipe member and an outer ring attached around the inner ring.

3. A dual-wheel hollow caster according to claim 1 or 2, characterized in that the bearing is a shielded ball bearing.

4. A dual-wheel hollow caster according to any one of claims 1 to 3, characterized in that the ball bearings are made of stainless steel.

Images