JPS5929441B2 - ball caster - Google Patents

Description

[Detailed description of the invention] The present invention relates to a ball caster.

More particularly, the lower opening of the cylindrical body is sealed by an intermediate body, and the upper opening of the cylindrical body is sealed by a rotatable ball whose outer surface projects from, but does not pass through, the opening. This product relates to a ball caster that uses fluid pressure.

Conventionally, as a ball caster using fluid pressure, a technique described in Japanese Patent Application Laid-Open No. 48-83541 is known.

This technique is an invention that backs up the ball by supplying pressurized air.

This invention not only requires equipment (such as a compressor) for supplying compressed air from the outside, but also has the disadvantage of weak backup power.

This is because even if a high-performance compressor or the like is used to increase the backup power, there is a certain limit to the compression of air.

By the way, even if the fluid pressure is the same, it is expected that a higher backup force can be obtained by using a liquid instead of a gas such as air.
When a rectangular fluid chamber as described in 8-83541 is used, shear stress acts on the corners of the fluid chamber (oil chamber) to back up the balls. One caster body is destroyed.

The present invention has been made in view of the above, and it is a technical object to prevent shear stress from acting on the fluid chamber (oil chamber) due to the fluid pressure in a ball caster that uses the fluid pressure. Take it as a challenge.

The technical means of the present invention is that in the ball caster using fluid pressure, an oil chamber filled with oil is formed in a portion surrounded by the ball, the cylindrical body, and the middle body,
The upper surface of the middle body constituting the nuclear oil chamber has an arcuate surface.

This eliminates corner parts in the oil chamber (fluid chamber), which prevents shear stress from concentrating on that part.
The fluid chamber) is not destroyed and can withstand high pressure.

That is, in the present invention, since there is no point where shear stress acts on the surface of the oil chamber (fluid chamber) that receives the static pressure of oil, the withstand pressure of the oil chamber (fluid chamber) can be reduced.

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

However, the present invention is not limited thereto.

In the figure, 1 is a ball caster, 2 is a ball, and a backup ring 4 and 01 are attached to the upper opening of the main body 3.
They are rotatably fitted together via a J-ring 5.

A middle body 6 having an arcuate surface corresponding to the inner surface (circumferential surface) of the ball 2 is screwed into the lower opening of the body 3 through a backup ring 4 and an 01J ring 5 so as to be movable up and down. , an oil chamber 7 having an arcuate surface is provided between the ball 2 and the ball 2 .

Furthermore, an inner hole 8 communicating with the oil chamber 7 is provided in the center of the inner body 6, and a blind stopper 1 is provided in the oil inlet 9 at the bottom of the inner hole 8.
0 is attached.

The oil chamber 7 forms a high-pressure container with the blind stopper 10 attached.

For example, it is a high-pressure container that allows high oil pressure to be applied to the oil chamber 7 using general hydraulic equipment with the blind stopper 10 removed.

The screwing force of the blind stopper 10 to the oil inlet 9 is also designed to withstand the above-mentioned high pressure.

According to a preferred embodiment of the present invention, it is desirable to provide a small-diameter ball 11 in contact with the ball 2 and a backup spring 12 to support the ball 2 in order to assist in backing up the ball 2 in the inner hole 8.

Note that this ball 11 and spring 12 are used to prevent the ball 2 from falling into the oil chamber 7 when there is no oil in the oil chamber 7 or when the amount of oil is reduced.
It is also possible to omit it.

The oil chamber 7 is formed into an oil chamber having an arcuate surface having an angle of 130 degrees or more, more preferably 140 degrees or more with respect to the center of the ball 2 (θ1 in FIG. 2 is the angle).

) This is the maximum suitable angle that can be taken in terms of design so that the pressure f□ applied from the ball 2 to the oil in the oil chamber 7 is dispersed over a wide range.

In the figure, f2 indicates the reaction from the oil to the ball 2.

Note that the outer main body 13 provided at the outermost side is screwed onto the main body 3, and a pedestal 14 is fixed by welding or the like.

The pedestal 14 has a rectangular shape such as a quadrangle, and an appropriate number of bolt holes 15 for attaching the ball caster main body 1 to the caster mounting surface are bored at the corners and the like.

An adhesive layer with release paper or a rubber plate may be provided on the lower surface of the pedestal 14 as required, or the lower surface may be formed into an arbitrary non-slip shape such as a corrugated shape.

And 16 is a pedestal 14 located at the bottom of the blank stopper 10
This is a hole for inserting a screwdriver or the like into the groove 17 provided in the blind stopper 10 and rotating it to move the middle body 6 up and down, and for removing the blind stopper 10 when replenishing oil. .

The usage of the above embodiment is as follows.

First, the blind plug 10 is removed, and oil is injected into the inner hole 8 from the oil inlet 9 to fill the oil chamber 7 and the inner hole 8 with oil.

In this case, care must be taken to prevent air from entering the oil chamber 7.

This is because mixing compressible air does not work well for backing up the ball. Once the oil is filled, screw the blind stopper 10 together and tighten the blind stopper 10 with a screwdriver or the like. do.

The oil in the oil chamber 7 is adjusted to about 1 to 5 Ky/criY, for example.

The hydraulic pressure is applied to keep the ball 2 in close contact with the upper opening of the main body 3 at all times, and although it does not require a very high pressure, it is large enough to contribute as a force for backing up the ball. is desirable.

As a pressurization adjustment means, when the blank stopper 10 is rotated and tightened, the inner body 6 also rotates, and the inner body 6 moves in the direction shown by the arrow in the figure (the state shown in the figure is Middle body 6
is increasing to its maximum.

). That is, the oil chamber 7 is narrowed and the oil pressure within the oil chamber 7 is increased.

Note that even when the oil in the oil chamber 7 decreases, the oil is prepared in the same manner as above.

When a load is applied to the ball 2 filled with oil as described above, the force acting in the oil chamber 7 is the force f1 exerted on the oil from the ball 2 and the reaction force f2, as shown in Fig. 2. It is in a state of balance.

That is, since the compressibility of the oil in the oil chamber 7 can be ignored, the nuclear force applied to the oil directly acts as a reaction from the internal pressure.

Next, an experimental example will be explained.

Ball caster 1 with ball 2 having a diameter of 50.8 mm
An experiment was conducted to determine how much load can be applied to the ball 2 when using the ball 2.

Prior to this experiment, we checked the high pressure inside the oil chamber 7 by removing the blind stopper 10 and connecting the oil inlet 9 to the hydraulic pump, and found that the oil pressure was 700 Kg/cI? t
There were no problems such as damage to the oil chamber 7 even when the oil chamber was used up to that point.

Now, apply a load of X to the ball 2 and apply a counter force f2 in the oil chamber 7.
= 700 Kff/cyi occurs, the following equation holds true.

X-f2×S ・・・・・・・・・・・・
... (1) (S: contact area of ball with oil chamber) Here, S is determined as follows.

θS=πR2×” ・・・・・・・・・・・・
... (2) 60 (R: Diameter of sphere) Substituting R = 5.08 crn and θ = 140° into equation (2), 40 S = (3, 14) (5, 08) 2X - 36〇 -31,53c11! L Substituting this into equation (1), X = 700x 31.53 = 22 ton, therefore 22
When a ton load is applied to the ball, the hydraulic reaction is 700 ton.
Ky/cyyt will be generated, and on the contrary, the oil chamber will be 70
It is estimated that if the pressure resistance is 0 Ky/cwt, it is possible to apply a load of 22 tons to the ball caster of the present invention.

Note that the compressibility of oil was ignored in the above calculations.

When a load of 22 tons was actually applied to ball 2, it was found that the hydraulic reaction was sufficient to back it up.

It is of course possible for those skilled in the art to modify the design, such as supplying hydraulic pressure from the outside to the oil inlet.

According to the present invention, since oil is used instead of air, there is no compressibility, so the backup force can be increased considerably.

Further, the same technical problem as the present invention can be solved by using water as the same liquid, but in contrast, since oil is used, it can also serve as a lubricating effect for the ball.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation of the above embodiment. In the figure, 1 is a ball caster, 2 is a ball, 3 is a main body, 6 is a middle body, 7 is an oil chamber, 8 is an inner hole, 10 is a blank plug, 13 is an outer body, 14 is a pedestal, and 16 is a hole. show.

Claims (1)

[Claims] 1. A ball caster in which the lower opening of the cylindrical body is sealed by an intermediate body, and the upper opening of the cylindrical body is sealed by a rotatable ball whose outer surface projects from the opening but does not pass through it. An oil chamber filled with oil is formed in a portion surrounded by the ball, the cylindrical body, and the middle body, and an upper surface of the middle body constituting the oil chamber corresponding to the inner surface of the ball is an arcuate surface. A ball caster with