JPS61263804A - Ball caster - Google Patents

Abstract

PURPOSE:To always back up a ball using the reaction of oil pressure and allow use of the ball caster for a long period of time by holding the ball in the upper opening of an upper main body through a sealing member and fitting the upper main body to an intermediate main body so as be slided. CONSTITUTION:When oil is used, a blind cork 10 is removed and an oil chamber 7, inside hole 8, and air vent hole 9 are filled with oil through a hole 11 from a hydraulic machine mounted on a collector 12. In addition, after the oil chamber 7 is filled with ample oil until the second member 3B of an upper main body 3 is engaged with a stopper 13, the blind cork 10 is tightened. If a load is applied to a ball 2 in this state, the force actuated in the oil chamber 7 is set in a state in which the force influenced on the oil from the ball 1 and the reacting force are balanced. Besides, if the load is applied to the ball 2 when the oil in the oil chamber 7 is reduce because the oil is used for a long period of time, a first member 3A slides and drops the ball 2 for an intermediate main unit 6 in cooperation with a second member 3B while the ball is being held.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ball caster. Specifically, even if the amount of oil filling the oil chamber decreases, the relative position of the cylindrical upper body that holds the ball is changed according to the decrease.
This invention relates to a ball caster that can constantly back up the ball using hydraulic reaction.

[Prior Art] Conventionally, as described in Japanese Patent Application Laid-Open No. 48-83541, a method of backing up the ball while supplying pressurized air is known as a ball caster using fluid pressure. Not only does it require equipment such as a compressor to supply compressed air from outside, but it also has the disadvantage of weak backup power. Even if a compressor capable of supplying high-pressure air is used to increase the backup force, for example, there is a certain limit to the air pressure, and a high backup force cannot be expected at all.

Therefore, the present inventor proposed an innovative pole caster that can obtain high pack-up force only by hydraulic reaction without applying any external backup force (Japanese Patent Publication No. 59-29441). (see, hereinafter this ball caster will be referred to as the "prior art ball caster").

[Problems to be Solved by the Invention] As a result of further efforts to improve the prior art ball caster, the present inventor found that when the work of applying a load of several tens of tons to the prior art ball caster continues for a long time, the oil in the oil chamber dries up. It has been found that there is a problem in that although there is a small amount of f, it leaks out to the outside. .

When we investigated the cause of this, we were able to obtain the following knowledge.

That is, according to the embodiment of the prior art ball caster shown in FIG. The one closest to the oil chamber was a straight cylinder type, and a ball was inserted and supported from the lower oil chamber side.

Therefore, the ball will not fall out from the upper opening of the main body, but it may fall off towards the oil chamber. 8 Normally, even if the ball drops a little, the sealing effect between the ball and the upper opening of the main body will not be achieved. The oil will not leak out.

However, if the prior art ball caster is used for a long time, the sealing effect is not perfect, so
As a result, it was found that it was inevitable that the oil would leak out little by little. When the oil level decreases and the ball can fall into the oil chamber even slightly, a gap will be created between the ball and the opening at the top of the main body, and an oil seal O-ring or backup ring will be inserted into the gap. However, it was found that it became curved and protruded outside the main body. That is, according to the examples of the prior art ball casters, it has been found that the cylindrical upper body only has a structure that prevents the balls from falling outside, but cannot prevent the balls from falling into the oil chamber.

Therefore, even if oil leaks outside and the amount of oil in the oil chamber decreases as described above, the present invention adjusts the relative position of the cylindrical upper body that holds the ball in accordance with the decrease. It is a technical problem to provide a ball caster that can be varied and always back up the ball by hydraulic reaction.

Means for Solving Problem E] The ball caster of the present invention which solves the above technical problem has the following features: 1. The lower opening of the cylindrical upper body is sealed by the middle body, and the upper opening of the cylindrical upper body is The ball is sealed by a rotatable ball whose outer surface projects outward but does not pass through the ball, and an oil chamber filled with oil is formed in a portion surrounded by the ball, the cylindrical upper body, and the middle body. The ball caster is characterized in that the ball is rotatably held in the upper opening of the cylindrical upper body via a sealing member, and the cylindrical upper body is slidably fitted into the middle body. do.

[Operation of the Invention] According to the present invention, the cylindrical upper body holds the ball and moves up or down together with the ball.

There is a device that solves the above technical problem by making the cylindrical upper body so that it can be lowered together with the ball as the amount of oil in the oil chamber decreases.

[Example] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

In the figure, 1 is a ball caster, and 2 is a ball, which is rotatably held in the upper opening of the upper body 3 via a sealing member such as a backup ring 4A and an O-ring 5A. The lower opening of the upper body 3 is sealed by the middle body 6 via a backup ring 4A and an O-ring 5A. In the present invention, the upper body 3 is joined to the outer periphery of the middle body 6 and is slidably fitted therein. ing.

7 is an oil chamber formed between the ball 2, the upper body 3, and the middle body 6. An inner hole 8 communicating with the oil chamber 7 is provided in the center of the inner body 6, and a blind stopper 10 is attached to an air vent hole 9 at the lowest part of the inner hole 8. The oil chamber 7 has the blind stopper 10
For example, with the blank stopper 10 removed, it is a high-pressure container that can apply high hydraulic pressure to the oil chamber 7 using general hydraulic equipment. The screwing force of the blind stopper 1G into the air vent hole 9 is also designed to withstand the above-mentioned high pressure.

In the embodiment, when oil is supplied to the oil chamber 7, it can be supplied from the air vent hole 9, but preferably a hole 11 in the middle body 6 leading to the oil chamber 7 and a chain hole 11 are connected to hydraulic equipment, etc. By providing a connector 12 for this purpose, oil can be supplied from outside of the ball caster 1.

In this embodiment, the upper main body 3 is composed of two members, a first member 3A and a second member 3B.

That is, the first member 3A forms the oil chamber 7 and also connects the ball 2 via the backup ring 4 and the O-ring 5A.
It is a member that is held from below to prevent the middle body 6 from falling downward, and a member that slides in contact with the middle body 6. On the other hand, the second member 3B is a member that holds the ball from above so as to prevent the ball 2 from being pulled out from the upper body 3, and also regulates the sliding length with respect to the middle body 6. It is a member, has a backup ring 4B and an O-ring 5B, and is screwed into the first member 3A.

As a means for rotatably holding the ball 2, two members, a first member 3M and a second member 3B, are used as shown below.
In addition, the contact surface of each member with the ball 2 can be made into a spherical surface, so that the ball 2 can be held so that it does not move up and down alone, but the present invention is not limited to this. After fitting the ball into the opening 3 from either side, fix another stopper member (for example, by welding) to the upper body so that the ball does not come off, and finally attach the ball to the upper and lower parts. You can also hold the ball from

The shape of the oil chamber 7 is not particularly limited, but as shown in Figure 1,
The oil chamber preferably has an arcuate surface, and is preferably formed in an oil chamber having an arcuate surface at an angle of 130 degrees or more, more preferably 140 degrees or more with respect to the center of the ball 2. In order to disperse the pressure applied to the oil in the oil chamber 7 over a wide range, this is the maximum suitable angle that can be taken in terms of design.

A stopper 13 for regulating the maximum amount of oil in the oil chamber 7 is attached to the middle body 6 so that the upper body 3 will not rise any further when the oil chamber 7 is filled with oil. Further, the middle body 6 is provided with a pedestal 14 that functions as a stopper to regulate the minimum allowable oil amount that can function as a ball caster even when the oil amount is low, and the oil chamber 7
As the amount of oil gradually decreases, the upper body 3 also descends accordingly, and the lower end of the first member 3A finally comes into contact with it.

Reference numeral 15 denotes a space formed between the stopper L3 and the pedestal 14, which may be filled with oil or the like as required.The lower surface of the pedestal 14 is provided with an adhesive layer with release paper, a rubber plate, etc. as necessary. Alternatively, the lower surface may be configured to have an arbitrary anti-slip shape such as a corrugated shape.

The usage of the above embodiment will be described below.

First, lower the ball caster as shown in Fig. 1, remove the blind stopper 10, and insert the hole 11 from the hydraulic equipment attached to the connector 12 into the oil chamber 7. Even the inner hole 8 and air vent hole 9 are filled with oil. In this case, the second member 3B of the upper body 3
It is important that enough oil is placed in the oil chamber 7 so that the stopper 13 engages with the stopper 13. In addition, care must be taken to prevent air from getting into the oil chamber 7, because if compressible air gets mixed in, it will not work well for backing up the ball. When it is filled with oil, screw on the blind stopper IG and tighten the blind stopper IO with a screwdriver or the like to make it blank.

When a load is applied to the ball 2 while it is filled with oil as described above, the force acting in the oil chamber 7 is a balance between the force exerted on the oil from the ball 2 and the reaction force.

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

Due to long-term use, the oil in the oil chamber 7 may become 1, for example, the ball 2.
If the oil film on the ball 2 decreases little by little as the ball 2 rotates, when a load is applied to the ball 2, the first member 3A, in cooperation with the second member 3B, will hold the ball 2 and move to the middle body. It will slide relative to 6 and go down in the drawing. Therefore, even if the amount of oil decreases, only the ball 2 will not be lowered, so there will be no gap between the ball 2 and the upper opening of the upper body 3. Therefore, the sealing members 4A and 5A are always sealed. [Effect] According to the present invention, there is no possibility that only the ball moves toward the oil chamber and a gap is created between the ball and the opening of the upper body, so that the sealing effect can be maintained properly at all times. can be maintained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. In the figure, l is a ball caster, 2 is a ball, 3 is an upper body, 3A is a first member, and 3B is a second member. 6 is the inner body, 7 is the oil chamber, 8 is the inner hole, 10 is the blank plug, 1
3 indicates a stopper, and 14 indicates a pedestal. Procedural amendment (voluntary) August 13, 1985

Claims (2)

[Claims] (1) The lower opening of the cylindrical upper body is sealed by the middle body, and the upper opening of the cylindrical upper body is sealed by a rotatable ball whose outer surface projects outward but does not pass through it. In the ball caster, an oil chamber filled with oil is formed in a portion surrounded by the ball, the cylindrical upper body, and the middle body, and the ball is inserted into the upper opening of the cylindrical upper body through a sealing member. What is claimed is: 1. A ball caster, which rotatably holds a ball caster, and has a cylindrical upper body slidably fitted into an inner body. (2) The ball caster according to claim 1, wherein the upper body comprises a first member and a second member that rotatably hold the ball.