Dual-wheel hollow caster and manufacturing method thereof

Abstract

To provide a double-wheel hollow caster of a simple constitution capable of easily enhancing slidability.SOLUTION: The double-wheel hollow caster 1 includes a body 13 having a hollow part 13A, a substantially cylindrical pipe member 13A arranged so as to penetrate the hollow part 11P, a pair of wheels 1515 attached to both ends of the pipe member 11P, and a single bearing 11B held between the body 13 and the pipe member 11. The single bearing 15 can be shared by the pair of wheels 15,15, and the slidability of the pair of wheels 15,15 can be easily improved by using a ball bearing as the single bearing 15.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[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. [Background technology]

[0002] For example, Patent Document 1 discloses a dual-wheel hollow caster in Figures 1 to 3. 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, making it less likely for parts to be damaged compared to a non-hollow dual-wheel caster. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-251653 Summary of the Invention [Problem to be solved by the invention]

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

[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. [Means for solving the problem]

[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. [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1(A) is a perspective view of a dual-wheel hollow caster according to this embodiment, and FIG. 1(B) is a perspective view of the dual-wheel hollow caster as seen from a different direction than that of FIG. 1(A). [Figure 2] Figure 2 is an exploded view of a dual-wheel hollow caster. [Figure 3] Figure 3(A) is an assembly diagram of the wheel, and Figure 3(B) is an assembly diagram of the bearing and its surroundings. [Figure 4] 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 AA in FIG. 4(A). DETAILED DESCRIPTION OF THE INVENTION

[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] Figure 1(A) is a perspective view of a dual-wheel hollow caster according to this embodiment, 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, Figure 3(B) is an assembly diagram of the surrounding area of ​​the bearing, 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 AA of Figure 4(A).

[0014] As shown in Figures 1 and 2, the double-wheel hollow caster 1 of this embodiment comprises a main body 13 having a hollow portion 13A, a roughly 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 has 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 positioned 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 raised above the floor.

[0018] 3(B), a single bearing 11B is sandwiched between the main body 13 and the pipe member 11P, and this bearing 11B is shared by the 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 for fixing the inner ring of bearing 11B to pipe member 11P and the method for fixing the outer ring of bearing 11B to main body 13 are, for example, as follows: First, bearing 11B is inserted into a mold for molding pipe member 11P and injection molded, thereby integrating the inner periphery of the inner ring of bearing 11B with pipe member 11P. Next, the integrated bearing 11B and pipe member 11P are inserted into a mold for molding main body 13 and injection molded, thereby integrating the outer periphery of the outer ring of bearing 11B with 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 when the components are assembled in a process after the molding process. Furthermore, 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 lubricious 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 member.

[0020] As explained 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 a ball bearing is used as this bearing 11B, it is easy to improve the sliding properties of the pair of wheels 15, 15 and the configuration is simple. 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, at least one of the diameter and width of the pair of wheels 15, 15, or the ratio of the diameter and width, can be changed depending on the application of the caster. [Explanation of symbols]

[0022] 1 Double hollow caster 11 axes 12 Cover 13 Main unit 13A Hollow part 13B Bearing section 11P Pipe material 11P-1 Mating part 11B bearing 15 wheels 15out outer ring 15in inner ring 15in-1 mated part

Claims

1. a main body having a hollow portion; a substantially cylindrical pipe member disposed so as to penetrate the hollow portion; a pair of wheels attached to both ends of the pipe member; a single bearing sandwiched between the main body and the pipe member; A double-wheel hollow caster characterized by comprising:

2. The dual-wheel hollow caster according to claim 1, Each of the pair of wheels is an inner ring attached to one end of the pipe member; an outer ring attached to the periphery of the inner ring; A double-wheel hollow caster characterized by comprising:

3. The dual-wheel hollow caster according to claim 1, The bearing is It is a shielded ball bearing A dual-wheel hollow caster characterized by:

4. The dual-wheel hollow caster according to claim 4, The ball bearing is made of stainless steel. A dual-wheel hollow caster characterized by:

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